Biphenyl type polythiol compound as well as preparation method and application thereof

Abstract

The invention discloses a biphenyl type polythiol compound and a preparation method and application thereof, the biphenyl type polythiol compound has a structural general formula as follows: # imgabs0 #, R1 and R2 are adjacent substituent groups on a benzene ring, R1 is mercaptopropyl, R2 is mercaptoalkoxy of C2-C18, f1m and f2n are other substituent groups on the benzene ring, and f1m and f2n are different substituent groups on the benzene ring. F1 and f2 are respectively and independently selected from any group except an organic metal group and a nucleophilic group, and m and n are respectively selected from any integer of 0-3. The sulfydryl alkyl and sulfydryl alkoxy ortho-substituted biphenyl type polythiol compound is prepared from the low-cost raw material biphenol, and the preparation method is simple, efficient, high in controllability, low in cost and suitable for batch preparation. When the ortho-substituted biphenyl polythiol compound is used as a curing agent, not only can low-temperature curing of a resin composition be realized, but also the bonding strength, heat and humidity resistance, mechanical property and waterproof property of cured resin can be remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a biphenyl type polythiol compound and a preparation method and application thereof. Background Art

[0002] With the rapid development of the electronics industry, the performance requirements for electronic packaging materials are getting higher and higher. Common resins are generally liquid or semi-solid at room temperature and need to be converted into solid through a curing process. Curing agent is a key component that causes epoxy resin to change from liquid to solid, and its type and performance directly affect the performance of the final cured product. Polythiol compounds have multiple thiol groups, which can react with epoxy groups or unsaturated groups in the resin to form thioether bonds. Due to their unique chemical structure and reactivity, this type of thiol curing agent can react with epoxy resin at low temperatures to form a stable three-dimensional network structure.

[0003] In the process of electronic packaging, low-temperature curing technology can reduce thermal stress, protect sensitive electronic components, and reduce energy consumption. In addition, low-temperature curing can shorten the production cycle and improve production efficiency. Although existing thiol curing agents have advantages in low-temperature curing, their insufficient heat resistance and moisture resistance limit their application in high-performance electronic packaging. In addition, in the manufacture of electronic products, low water absorption glue can be used to bond electronic components and circuit boards. The bonded electronic components and circuit boards are not prone to short circuits and damage in a humid environment, thereby improving the reliability and safety of electronic products. Based on the requirements of electronic products for waterproofing, insulation and other functions, the toughness requirements of electronic packaging materials are relatively high to avoid problems such as breakage or degumming of packaging materials under external stress, which leads to sealing failure and affects the service life of electronic products.

[0004] Based on this, there is an urgent need for a curing agent that can not only be used for low-temperature curing of resins, but also the resin cured by it has good moisture and heat resistance, low water absorption and toughness, and can be used to prepare adhesives or sealants for electronic products to improve the reliability and safety of electronic products. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a biphenyl type polythiol compound and a preparation method and application thereof. The biphenyl type polythiol compound not only contains a rigid biphenyl structure and four flexible alkylthiol groups, but also two alkylthiol groups distributed on the benzene ring are in ortho positions. The compound is used as a curing agent to cure the resin. The cured resin not only has excellent moisture and heat resistance, but also exhibits good mechanical properties, so that the resin composition containing the biphenyl type polythiol compound is suitable for adhesives or sealing materials for electronic products.

[0006] Specifically, the following technical solutions are provided:

[0007] The first aspect of the present invention provides a biphenyl type polythiol compound, wherein the biphenyl type polythiol compound has the following general structural formula:

[0008]

[0009] Among them, R 1 With R 2 On the benzene ring, R 1 is -(CH2)3SH, R 2 For-OR 3 SH, R 3 is a C2-C18 alkylene group;

[0010] f 1 and f 2 Remove R from biphenyl 1 , R 2 The other substituents are independently selected from any group except the organic metal group and the nucleophilic group; m and n are the substituents f 1 、f 2 The number of substitutions on the biphenyl, m and n, are independently selected from any integer between 0 and 3; i.e., f 1 m represents m substituents f 1 Replace the hydrogen on biphenyl, f 2 n represents n substituents f 2 Replace hydrogen on biphenyl;

[0011] When f 1 When located at biphenyl site 1 and / or site 2, the f 1 One selected from H, F, Cl, methyl, trifluoromethyl;

[0012] When f 2 When located at biphenyl site 3 and / or site 4, the f 2 One selected from H, F, Cl, methyl and trifluoromethyl.

[0013] Furthermore, the nucleophilic group includes hydroxyl, amino, carboxyl, phosphate and other groups.

[0014] Furthermore, the f 1 and f 2 They are independently selected from one or more of H, F, Cl, alkyl and haloalkyl.

[0015] Furthermore, the biphenyl type polythiol compound has a structure shown by formula (I) to formula (III):

[0016]

[0017] Among them, R 3 It is a C2-C18 alkylene group.

[0018] Furthermore, the biphenyl type polythiol compound is

[0019] The second aspect of the present invention provides a method for preparing the biphenyl type polythiol compound according to the first aspect, comprising the following steps: under a protective atmosphere,

[0020] S1, reacting the biphenyl diphenol compound represented by formula a and the compound represented by formula b in the presence of a first alkaline reagent, a first phase transfer catalyst and a first solvent to obtain a first intermediate product represented by formula c;

[0021] S2, heating the first intermediate product to obtain a second intermediate product represented by formula d;

[0022] S3, reacting the second intermediate product with the compound represented by formula e in the presence of a second base reagent, a second phase transfer catalyst and a second solvent to obtain a third intermediate product represented by formula f;

[0023] S4, reacting the third intermediate product with thioacetic acid in the presence of a free radical initiator and a third solvent to obtain a fourth intermediate product represented by formula g;

[0024] S5, reacting the fourth intermediate product with an acid reagent in the presence of a fourth solvent to obtain the biphenyl-type polythiol compound;

[0025] The structures of the above formula a-formula g are as follows:

[0026]

[0027] Wherein, X is bromine or chlorine;

[0028] l is selected from any integer from 0 to 16.

[0029] Furthermore, the protective atmosphere includes but is not limited to nitrogen.

[0030] Further, in S1, the first alkaline reagent is selected from one or more of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, triethylamine, and p-dimethylaminopyridine; in some preferred embodiments, the first alkaline reagent is potassium carbonate, potassium hydroxide or sodium hydroxide.

[0031] Furthermore, in S1, the first phase transfer catalyst is selected from one or more of crown ethers, onium salts, ammonium salts, sulfonium salts, arsenic salts, polyethers, non-cyclic polyethers and tertiary amine catalysts; in some preferred embodiments, the first phase transfer catalyst is 18-crown ether-6, triethylamine or tetrabutylammonium bromide.

[0032] Furthermore, in S1, the first solvent is selected from one or more of acetone, ethyl acetate, tetrahydrofuran, N,N'-dimethylformamide, dichloromethane, dioxane, ethanol, and methanol; in some preferred embodiments, the first solvent is acetone, ethyl acetate or dichloromethane.

[0033] Furthermore, in S1, the reaction temperature is preferably 60-90°C, and the reaction time is preferably 6-15h.

[0034] Furthermore, in S2, the temperature of the heating reaction is preferably 150-250°C, and the time of the heating reaction is preferably 10-18h.

[0035] Further, in S3, the second alkaline reagent is selected from one or more of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, triethylamine, and p-dimethylaminopyridine; in some preferred embodiments, the second alkaline reagent is potassium carbonate, potassium hydroxide or sodium hydroxide.

[0036] Furthermore, in S3, the second phase transfer catalyst is selected from one or more of crown ethers, onium salts, ammonium salts, sulfonium salts, arsenic salts, polyethers, non-cyclic polyethers and tertiary amine catalysts; in some preferred embodiments, the second phase transfer catalyst is 18-crown ether-6, triethylamine or tetrabutylammonium bromide.

[0037] Furthermore, in S3, the second solvent is selected from one or more of acetone, ethyl acetate, tetrahydrofuran, N,N'-dimethylformamide, dichloromethane, dioxane, ethanol, and methanol; in some preferred embodiments, the second solvent is acetone, ethyl acetate or dichloromethane.

[0038] Furthermore, in S3, the reaction temperature is 60-90°C, and the reaction time is 6-15h.

[0039] Furthermore, in S4, the free radical initiator is selected from one or more of azo, organic peroxide and redox initiators; in some preferred embodiments, the free radical initiator is azobisisobutyronitrile or benzoyl peroxide.

[0040] Furthermore, in S4, the third solvent is selected from one or more of acetone, ethyl acetate, tetrahydrofuran, N,N'-dimethylformamide, dichloromethane, dioxane, ethanol, and methanol; in some preferred embodiments, the third solvent is tetrahydrofuran or N,N'-dimethylformamide.

[0041] Furthermore, in S4, the reaction temperature is preferably 60-90° C., and the reaction time is preferably 15-25 h.

[0042] Furthermore, in S5, the acid reagent includes but is not limited to hydrochloric acid, sulfuric acid, etc., to promote the hydrolysis of ester bonds. Preferably, the concentration of the acid reagent in the reaction system is preferably 0.8-1.3 mol / L.

[0043] Furthermore, in S5, the fourth solvent is selected from one or more of acetone, ethyl acetate, tetrahydrofuran, N,N'-dimethylformamide, dichloromethane, dioxane, ethanol, and methanol; in some preferred embodiments, the fourth solvent is a tetrahydrofuran / methanol (volume ratio 1:1) mixed solvent or a N,N'-dimethylformamide / methanol (volume ratio 1:1) mixed solvent.

[0044] Furthermore, the reaction temperature is preferably 55-95° C., and the reaction time is preferably 25-40 h.

[0045] The third aspect of the present invention provides a resin composition, comprising a resin and a curing agent, wherein the curing agent comprises the biphenyl-type polythiol compound described in the first aspect; the resin includes one or more of epoxy resin, photosensitive resin, benzaldehyde compound, olefin having carbon-carbon double bond in the molecule, and acrylate compound.

[0046] Furthermore, the resin composition also includes a curing accelerator. When the resin is an epoxy resin, the curing accelerator is an amine, such as PN23; when the resin is a combination of an epoxy resin and a photosensitive resin, the curing accelerator is a free radical photoinitiator and an amine, such as (2,4,6-trimethylbenzoyl)diphenylphosphine oxide and PN23; when the resin is a benzaldehyde compound, the curing accelerator is trifluoroacetic acid; when the resin is an olefin or acrylate compound having a carbon-carbon double bond in the molecule, the curing accelerator is a free radical photoinitiator, such as 2,2-dimethoxy-2-phenylacetophenone.

[0047] The fourth aspect of the present invention provides a use of the resin composition described in the third aspect in the preparation of an adhesive or a sealant.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The present invention provides a biphenyl type polythiol compound, the compound molecule contains a rigid biphenyl structure and four flexible alkylthiol groups, and the two alkylthiol groups distributed on the benzene ring are in the ortho position. The biphenyl structure gives the cured resin good heat resistance, and the four thiol groups with a specific position structure can further improve the heat resistance of the cured resin through high crosslinking density, and can significantly improve the toughness of the cured resin. In addition, the biphenyl type polythiol compound is liquid at room temperature, has a low viscosity, and can be directly used as a curing agent in the curing process of the resin composition.

[0050] The invention provides a method for preparing biphenyl type polythiol compounds at low cost. The biphenyl type polythiol compounds are prepared by taking biphenyl diphenol with low cost as a raw material, and the costs of solvents, catalysts and other raw materials in the synthesis process are all low, thereby realizing the low-cost preparation of biphenyl type polythiol compounds. For example, the small-scale test cost of 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl is only 3.5 yuan / g (the cost can be further reduced by mass production), and the cost of the starting raw material (5,5'-diallyl-2,2'-biphenyl, 68 yuan / g) required for preparing 5,5'-bis(3-mercaptopropyl)-2,2'-bis(3-mercaptopropoxy)biphenyl in the prior art has exceeded 43 yuan / g, thereby greatly reducing the preparation cost of the biphenyl type polythiol compounds. In addition, the method has simple and efficient synthesis steps, strong process controllability, high yield of target products, and is suitable for mass production.

[0051] The biphenyl type polythiol compound provided by the present invention is used as a curing agent in a resin composition, so that the resin composition can be cured quickly under low temperature conditions, and the internal stress and shrinkage generated during curing are small; at the same time, because the curing agent has a high functionality and does not have an easily hydrolyzed group, the resin composition containing the curing agent can produce a high crosslinking density after curing and is not easy to hydrolyze, thereby significantly improving the bonding strength, heat and moisture resistance, toughness, etc. of the cured resin. Compared with biphenyl type polythiol compounds substituted with mercaptoalkyl and mercaptoalkoxy ortho-positions, the resin composition prepared by using the biphenyl type polythiol compound substituted with mercaptoalkyl and mercaptoalkoxy ortho-positions provided by the present invention as a curing agent has better bonding strength, heat and moisture resistance, toughness and low water absorption after curing, and is more suitable for preparing adhesives, sealing materials, etc. for electronic products. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A physical picture of 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl prepared in Example 1;

[0053] Figure 2 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl prepared in Example 1 1 H-NMR spectrum;

[0054] Figure 3 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl prepared in Example 1 13 C-NMR;

[0055] Figure 4 This is the IR spectrum of 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl prepared in Example 1. DETAILED DESCRIPTION

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0057] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0058] The sources of some of the raw materials used in the following examples and comparative examples are as follows:

[0059]

[0060] Example 1

[0061] This embodiment provides a preparation method of a biphenyl type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl, and the specific preparation method is as follows:

[0062] (1) 18.6 g of 4,4'-dihydroxybiphenyl and 36.3 g of allyl bromide were dissolved in 250 mL of acetone, and then 55.3 g of anhydrous potassium carbonate and 2.6 g of 18-crown ether-6 were added, and the mixture was stirred at 70° C. for 12 h under N2 protection. After filtering, the solvent and excess raw materials in the filtrate were removed by reduced pressure distillation, and the filtrate was washed with water and dried to obtain a first intermediate product with a yield of 94%;

[0063] (2) 26.6 g of the first intermediate product was heated to 200° C. under N2 protection for 13 h, and purified to obtain the second intermediate product with a yield of 84%;

[0064] (3) 26.6 g of the second intermediate product and 36.3 g of allyl bromide were dissolved in 250 mL of acetone, 55.3 g of anhydrous potassium carbonate and 2.6 g of 18-crown ether-6 were added, and the mixture was stirred at 70° C. for 10 h under N2 protection. After filtering, the solvent and excess raw materials in the filtrate were removed by reduced pressure distillation, and the filtrate was washed with water and dried to obtain a third intermediate product with a yield of 89%;

[0065] (4) 34.7 g of the third intermediate product and 45.7 g of thioacetic acid were dissolved in 300 mL of tetrahydrofuran, and 3.3 g of azobisisobutyronitrile was added. The mixture was stirred at 65° C. for 16 h under N2 protection. After filtering, the solvent and excess raw materials in the filtrate were removed by reduced pressure distillation. The filtrate was washed with water and dried to obtain a fourth intermediate product with a yield of 80%;

[0066] (5) 65.1 g of the fourth intermediate product and 10 g of concentrated hydrochloric acid were dissolved in 150 mL of tetrahydrofuran and 150 mL of methanol, and the mixture was stirred at 65° C. for 33 h under N2 protection. After filtering, the solvent and excess raw materials in the filtrate were removed by reduced pressure distillation, and the mixture was washed with water and dried to obtain the product 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl.

[0067] The product prepared in this example is Figure 1 As shown, it is liquid at room temperature and has a low viscosity; the NMR hydrogen spectrum, carbon spectrum and infrared spectrum of the product are shown as follows Figure 2-4 As shown, 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl was prepared.

[0068] Example 2

[0069] The present embodiment provides a thermosetting resin composition, which includes the following components in parts by mass: 55 parts of bisphenol A epoxy resin, 40 parts of the biphenyl type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl prepared in Example 1, and 0.55 parts of a latent curing accelerator (PN23) (1% of the epoxy resin).

[0070] The above raw materials are mixed uniformly at room temperature, and then degassing is performed, and the discharged materials are packaged into sealed rubber tubes to obtain a resin composition.

[0071] Example 3

[0072] The present embodiment provides a photocurable resin composition, which includes the following components in parts by mass: 35 parts of triallyl isocyanurate, 50 parts of the biphenyl-type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl prepared in Example 1, and 0.7 parts of 2,2-dimethoxy-2-phenylacetophenone (2% of the UV resin).

[0073] The above raw materials are mixed uniformly at room temperature and in the dark, and then degassing is performed. The discharged materials are packaged into black or brown sealed rubber tubes to obtain a resin composition.

[0074] Example 4

[0075] This embodiment provides a light-thermal dual-curing resin composition, which includes the following components in parts by mass:

[0076] 55 parts of bisphenol A epoxy resin, 40 parts of tricyclodecane dimethanol diacrylate resin, 40 parts of the biphenyl type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl prepared in Example 1, 0.55 parts of latent curing agent (PN23), 0.8 parts of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (2% of the photosensitive resin).

[0077] The above raw materials are mixed uniformly under light-proof and room temperature conditions, and then degassing treatment is performed. The discharged materials are packaged into black or brown sealed rubber tubes to obtain a resin composition.

[0078] Example 5

[0079] The present embodiment provides a room temperature curing resin composition, which includes the following components in parts by mass: component A includes 20 parts of 4-hydroxy-3-methoxybenzaldehyde and 2.6 parts of trifluoroacetic acid (13% of the benzaldehyde resin), and component B includes 50 parts of the biphenyl type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl prepared in Example 1.

[0080] The raw materials of components A and B are respectively mixed evenly at room temperature, and then degassing is performed, and the discharged materials are dividedly packaged into sealed double tubes A and B to obtain a resin composition.

[0081] Comparative Example 1

[0082] This comparative example provides a thermosetting resin composition, which differs from Example 2 only in that an equal amount of commercial polythiol curing agent pentaerythritol tetrakis(3-mercaptopropionate) ester is used to replace the biphenyl type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl, and the rest are the same to prepare a resin composition.

[0083] Comparative Example 2

[0084] This comparative example provides a photocurable resin composition, which differs from Example 3 only in that an equal amount of commercial polythiol curing agent pentaerythritol tetrakis(3-mercaptopropionate) is used to replace the biphenyl-type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl, and the rest are the same to prepare a resin composition.

[0085] Comparative Example 3

[0086] This comparative example provides a photothermal dual-curing resin composition, which differs from Example 4 only in that an equal amount of commercial polythiol curing agent pentaerythritol tetrakis(3-mercaptopropionate) ester is used to replace the biphenyl-type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl, and the rest are the same to prepare a resin composition.

[0087] Comparative Example 4

[0088] This comparative example provides a room temperature curing resin composition, which differs from Example 5 only in that an equal amount of commercial polythiol curing agent pentaerythritol tetrakis(3-mercaptopropionate) ester is used to replace the biphenyl type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl, and the rest are the same to prepare a resin composition.

[0089] Comparative Example 5

[0090] This comparative example provides a heat-curable resin composition, which is different from Example 2 only in that an equal amount of 5,5'-bis(3-mercaptopropyl)-2,2'-bis(3-mercaptopropoxy)biphenyl (structure: ) is substituted for the biphenyl type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl, and the rest are the same to prepare a resin composition.

[0091] Comparative Example 6

[0092] This comparative example provides a photocurable resin composition, which differs from Example 3 only in that an equal amount of 5,5'-bis(3-mercaptopropyl)-2,2'-bis(3-mercaptopropoxy)biphenyl is used to replace the biphenyl-type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl, and the rest are the same to prepare a resin composition.

[0093] Comparative Example 7

[0094] This comparative example provides a photothermal dual-curing resin composition, which differs from Example 4 only in that an equal amount of 5,5'-bis(3-mercaptopropyl)-2,2'-bis(3-mercaptopropoxy)biphenyl is used to replace the biphenyl-type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl, and the rest are the same to prepare a resin composition.

[0095] Comparative Example 8

[0096] This comparative example provides a room temperature curing resin composition, which differs from Example 5 only in that an equal amount of 5,5'-bis(3-mercaptopropyl)-2,2'-bis(3-mercaptopropoxy)biphenyl is used to replace the biphenyl-type polythiol compound 4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl, and the rest are the same to prepare a resin composition.

[0097] Performance Testing

[0098] The performance tests of the resin compositions prepared in the above Examples 2-5 and Comparative Examples 1-8 are as follows:

[0099] Curing conditions:

[0100] The resin compositions prepared in Example 2 and Comparative Examples 1 and 5 were extruded from a rubber hose using a dispensing machine and then cured at 80° C. for 60 minutes to obtain cured samples.

[0101] The resin compositions prepared in Example 3 and Comparative Examples 2 and 6 were squeezed out from a rubber tube using a dispensing machine, and then exposed to ultraviolet light (wavelength 365 nm, light intensity 1000 mW / cm 2 ) Radiation curing for 15 seconds to obtain a cured sample.

[0102] The resin compositions prepared in Example 4 and Comparative Examples 3 and 7 were squeezed out from a rubber tube using a dispensing machine and firstly exposed to ultraviolet light (wavelength of 365 nm, light intensity of 1000 mW / cm 2 ) radiation curing for 5 seconds and then curing at 80°C for 60 minutes to obtain a cured sample.

[0103] The resin compositions prepared in Example 5 and Comparative Examples 4 and 8 were extruded from double-tube packages using a dispensing machine, mixed in a static mixer, and then cured at room temperature for 24 hours to obtain cured samples.

[0104] (1) Glass transition temperature (°C): The test was conducted using a Q-800 dynamic mechanical analysis tester (DMA) from TA Instruments, USA. The resin compositions prepared in the above embodiments and comparative examples were completely cured to form a 42 mm × 8 mm × 0.3 mm sheet. The change of the loss factor (tan δ) with temperature was measured in a liquid nitrogen atmosphere and film stretching mode within a temperature range of -40 to 250°C. The heating rate was 10°C / min and the test frequency was 10 Hz, so as to determine the glass transition temperature T of the cured resin composition. g (℃).

[0105] (2) Bond strength (MPa) and elongation at break (%): The resin compositions prepared in the above embodiments and comparative examples were coated on sheets to prepare test samples. The bonding area was 25.4 mm×5 mm, and the thickness of the adhesive layer was 0.1 mm. The test samples were cured respectively. Then, the two sheets of the completely cured samples were pulled apart in opposite directions using a universal testing machine. The tests were performed at an ambient temperature of 25°C, and the measured force values ​​were recorded as strength (MPa). The cured samples were subjected to heating and humidification conditions of 85°C / 85%RH / 750h, and the shear bond strength (MPa) and elongation at break (%) of the samples were tested again at an ambient temperature of 25°C and recorded.

[0106] (3) Water absorption (%): The resin compositions prepared in the above examples and comparative examples were respectively made into block samples with a size of 20×10×5 mm, and then the test samples were cured. The completely cured samples were placed in 80° C. distilled water and soaked at 80° C. for 24 h. The samples were taken out and weighed, and the water absorption (%) was calculated.

[0107] The above test results are shown in Table 1 below:

[0108] Table 1

[0109]

[0110] As can be seen from Table 1, the glass transition temperature, bonding strength at room temperature, bonding strength after heating and humidification, and elongation at break after heating and humidification of the resin compositions (Examples 2-5) prepared using 4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl prepared in Example 1 as a curing agent are significantly higher than those of the resin compositions prepared using commercially available pentaerythritol tetrakis(3-mercaptopropionic acid) as a curing agent (Comparative Examples 1-4, wherein Example 2 VS Comparative Example 1, Example 3 VS Comparative Example 2, Example 4 VS Comparative Example 3, and Example 5 VS Comparative Example 4).

[0111] It can be seen from Examples 2-5 and Comparative Examples 5-8 that, compared with tetramercaptobiphenyl substituted at the para position with mercaptoalkyl or mercaptoalkoxy, the resin composition prepared by using tetramercaptobiphenyl (4,4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl) substituted at the ortho position with mercaptoalkyl or mercaptoalkoxy as a curing agent has a relatively low T g, but showed higher room temperature bonding strength, and the bonding strength and elongation at break after heating and humidification were significantly higher than those of the resin composition cured with 5,5'-bis(3-mercaptopropyl)-2,2'-bis(3-mercaptopropoxy)biphenyl as a curing agent. This also shows that the resin composition prepared with 4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl prepared in Example 1 as a curing agent has better bonding strength, moisture and heat resistance and toughness after curing.

[0112] In addition, it can be seen from the results of the water absorption test that compared with commercial tetrakis(3-mercaptopropionic acid) pentaerythritol ester and tetrakismercaptobiphenyl 5,5'-bis(3-mercaptopropyl)-2,2'-bis(3-mercaptopropoxy)biphenyl substituted with mercaptoalkyl and mercaptoalkoxy groups, the resin composition prepared using 4'-bis(3-mercaptopropoxy)-3,3'-bis(3-mercaptopropyl)biphenyl prepared in Example 1 as a curing agent has a significantly lower water absorption rate after curing, showing better waterproof properties.

[0113] In summary, the biphenyl-type polythiol compound prepared by the present invention has a rigid biphenyl structure and no ester bond, is liquid at room temperature, has low viscosity and good processability; the resin composition prepared using the biphenyl-type polythiol compound can be rapidly cured at a relatively low temperature, and has excellent moisture and heat resistance, toughness and water resistance after curing, and can be widely used in adhesives, coatings, sealing materials, etc.

[0114] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A biphenyl type polythiol compound, characterized in that The biphenyl type polythiol compound has the following general structural formula: Among them, R 1 With R 2 On the benzene ring, R 1 -(CH2)3SH, R 2 For-OR 3 SH, R 3 is a C2-C18 alkylene group; f 1 and f 2 Remove R from biphenyl 1 , R 2 The other substituents are independently selected from any group except the organic metal group and the nucleophilic group; m and n are the substituents f 1 、f 2 The number of substitutions on the biphenyl, m and n, are independently selected from any integer between 0 and 3; When f 1 When located at biphenyl site 1 and / or site 2, the f 1 One selected from H, F, Cl, methyl, trifluoromethyl; When f 2 When located at biphenyl site 3 and / or site 4, the f 2 One selected from H, F, Cl, methyl and trifluoromethyl.

2. The biphenyl type polythiol compound according to claim 1, characterized in that The biphenyl type polythiol compound has a structure shown in formula (I) to formula (III): Among them, R 3 It is a C2-C18 alkylene group.

3. A method for preparing the biphenyl type polythiol compound according to claim 1 or 2, characterized in that: The following steps are involved: In a protective atmosphere, S1, reacting the compound represented by formula a and the compound represented by formula b in the presence of a first base reagent, a first phase transfer catalyst and a first solvent to obtain a first intermediate product represented by formula c; S2, heating the first intermediate product to obtain a second intermediate product represented by formula d; S3, reacting the second intermediate product with the compound represented by formula e in the presence of a second base reagent, a second phase transfer catalyst and a second solvent to obtain a third intermediate product represented by formula f; S4, reacting the third intermediate product with thioacetic acid in the presence of a free radical initiator and a third solvent to obtain a fourth intermediate product represented by formula g; S5, reacting the fourth intermediate product with an acid reagent in the presence of a fourth solvent to obtain the biphenyl-type polythiol compound; The structures of the above formula a-formula g are as follows: Wherein, X is bromine or chlorine; l is selected from any integer from 0 to 16.

4. The preparation method according to claim 3, characterized in that: In S1, the first alkaline reagent is selected from one or more of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, triethylamine, and p-dimethylaminopyridine; The first phase transfer catalyst is selected from one or more of crown ethers, onium salts, ammonium salts, sulfonium salts, arsenic salts, polyethers, acyclic polyethers and tertiary amine catalysts; The first solvent is selected from one or more of acetone, ethyl acetate, tetrahydrofuran, N,N'-dimethylformamide, dichloromethane, dioxane, ethanol, and methanol; The reaction temperature is 60-90° C., and the reaction time is 6-15 hours.

5. The preparation method according to claim 3, characterized in that: In S2, the temperature of the heating reaction is 150-250°C, and the heating reaction time is 10-18h.

6. The preparation method according to claim 3, characterized in that: In S3, the second alkaline reagent is selected from one or more of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, triethylamine, and p-dimethylaminopyridine; The second phase transfer catalyst is selected from one or more of crown ethers, onium salts, ammonium salts, sulfonium salts, arsenic salts, polyethers, acyclic polyethers and tertiary amine catalysts; The second solvent is selected from one or more of acetone, ethyl acetate, tetrahydrofuran, N,N'-dimethylformamide, dichloromethane, dioxane, ethanol, and methanol; The reaction temperature is 60-90° C., and the reaction time is 6-15 hours.

7. The preparation method according to claim 3, characterized in that: In S4, the free radical initiator is selected from one or more of azo initiators, organic peroxide initiators and oxidation-reduction initiators; The third solvent is selected from one or more of acetone, ethyl acetate, tetrahydrofuran, N,N'-dimethylformamide, dichloromethane, dioxane, ethanol, and methanol; The reaction temperature is 60-90° C., and the reaction time is 15-25 h.

8. The preparation method according to claim 3, characterized in that: In S5, the acid reagent is hydrochloric acid and / or sulfuric acid; The fourth solvent is selected from one or more of acetone, ethyl acetate, tetrahydrofuran, N,N'-dimethylformamide, dichloromethane, dioxane, ethanol, and methanol; The reaction temperature is 55-95° C., and the reaction time is 25-40 hours.

9. A resin composition, characterized in that Comprising a resin and a curing agent, wherein the curing agent comprises the biphenyl type polythiol compound according to claim 1 or 2; The resin includes one or more of epoxy resin, photosensitive resin, benzaldehyde compound, olefin compound with carbon-carbon double bond in molecule, and acrylate compound.

10. Use of the resin composition according to claim 9 in preparing an adhesive or a sealant.

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