A high-adhesion-strength bio-based epoxy resin and its synthesis method

Abstract

This invention discloses a high-adhesion-strength bio-based epoxy resin by grafting furan rings, phosphate groups, silane groups, and isocyanurate rings onto the epoxy resin molecule. The furan rings enhance the epoxy resin's flexibility and adhesion to substrates; the phosphate groups significantly improve the adhesion between the epoxy resin and substrates, especially metals; the silane groups significantly improve the epoxy resin's high-temperature and high-humidity resistance; and the trimeric isocyanurate cyclic structure greatly improves the epoxy resin's heat resistance. This resin exhibits excellent overall performance and superior storage stability.

Description

Technical Field

[0001] This invention relates to a high-adhesion-strength bio-based epoxy resin and its synthesis method, belonging to the field of polymer adhesives. Background Technology

[0002] Epoxy adhesives, as an important class of thermosetting polymer adhesives, possess characteristics such as low curing shrinkage, high bond strength, low residual stress, and high bulk strength and modulus, and are widely used in composite materials, electronic packaging, automotive, and architectural coatings. However, conventional epoxy adhesives suffer from drawbacks such as high hardness, poor toughness, and poor resistance to mechanical and thermal shock after curing, which limits their practical applications. For example, in application testing for vehicle body structural bonding, not only is high bond strength required, but the failure mode after aging must also be the destruction of the adhesive layer itself, ensuring safety during service. While conventional epoxy adhesives often meet the bond strength requirement, their failure mode after aging is often the destruction of the adhesive layer at the substrate interface, thus reducing safety. Epoxy resin, as the main component of epoxy structural adhesives, plays a crucial role in influencing their performance. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a high-adhesion-strength bio-based epoxy resin and its synthesis method. The products obtained from this resin exhibit high initial adhesive strength, excellent resistance to temperature shock, high temperature and humidity, and dry heat resistance, thus meeting the requirements for structural bonding workability, reliability, and strength.

[0004] The technical solution of the present invention to solve the above problems is as follows:

[0005] A method for synthesizing a high-adhesion-strength bio-based epoxy resin includes the following steps:

[0006] Step 1: Epoxy resin and bio-based furanyl dicarboxylic acid (FDCA) are reacted at 80-120℃ in a molar ratio of 2~2.2:1 under the action of catalyst a until the acid value is ≤0.2mgKOH / g, to obtain prepolymer A;

[0007] Step 2: React aminosilane and diisocyanate trimer in an equimolar ratio at room temperature to 60°C until the NCO group reaches the designed value. Then add amino phosphate and react at room temperature to 60°C until the NCO group reaches the designed value to form prepolymer B.

[0008] The third step involves adding prepolymer A to prepolymer B and reacting it at room temperature to 90°C under the action of catalyst b until the NCO groups disappear.

[0009] Furthermore, the epoxy resin refers to a substance whose molecular structure contains at least two epoxy functional groups, preferably a structure containing glycidyl ether groups.

[0010] Furthermore, catalyst a refers to a catalyst that can effectively catalyze the reaction of epoxy and carboxyl groups, including triphenylphosphine, tetrabutylammonium bromide, dimethylaniline, N,N-dimethylbenzylamine, triethylbenzylamine chloride, or triethylamine, and its addition amount is from one-thousandth to one-hundredth of the total mass of prepolymer A, preferably triphenylphosphine.

[0011] Furthermore, the aminosilane refers to a structure containing a primary or secondary amino group on its molecule, and simultaneously containing a silylmethoxy or silylethoxy group, including N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and di(γ-trimethoxysilylpropyl)amine.

[0012] Furthermore, the diisocyanate trimer includes HDI trimer, IPDI trimer, and preferably HDI trimer.

[0013] Furthermore, the aminophosphate ester refers to a structure containing a primary or secondary amino group and a phosphate group on its molecule, including aminomethylphosphonic acid, (1-aminobutyl)phosphonic acid, (1-aminooctyl)phosphonic acid, and 4-aminobutane-1-phosphonic acid.

[0014] Furthermore, catalyst b comprises an organotin, bismuth, zinc or zirconium catalyst, preferably an organobismuth catalyst.

[0015] The beneficial effects of this technical solution are as follows: This solution grafts furan rings, phosphate groups, silane groups, and isocyanurate rings onto epoxy resin molecules. The furan rings improve the flexibility and adhesion of the epoxy resin to the substrate; the phosphate groups significantly enhance the adhesion between the epoxy resin and the substrate, especially metals; the silane groups significantly improve the epoxy resin's resistance to high temperatures and humidity; and the trimeric isocyanurate cyclic structure greatly improves the epoxy resin's heat resistance. Compared to simple physical mixtures of components and commercially available resins, this resin exhibits superior overall performance and excellent storage stability. Detailed Implementation

[0016] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0017] Example 1

[0018] 514g of 1,4-cyclohexanediethanol diglycidyl ether, 156.1g of bio-based FDCA, and 2g of triphenylphosphine were added sequentially to the reactor. The mixture was stirred at 100-110℃ until the acid value was ≤0.2mgKOH / g, and the product was discharged to obtain prepolymer A. 504.58g of HDI trimer and 221.4g of 3-aminopropyltriethoxysilane were added sequentially to the reactor. The mixture was stirred at 40℃ for 0.5-1h until the NCO group content was ≤11.57%. 209.22g of (1-aminooctyl)phosphoric acid was added to the reactor, and the mixture was stirred at 40℃ until the NCO group content was ≤4.5% to obtain prepolymer B. 670.1g of prepolymer A and 0.8g of BiCAT Z catalyst from Leading Chemicals (USA) were added to the reactor, and the mixture was reacted at 40-60℃ until the NCO groups disappeared to obtain high-adhesion bio-based epoxy resin A.

[0019] At room temperature, by weight, take 100 parts of high-adhesion bio-based epoxy resin A, 20 parts of neopentyl glycol diglycidyl ether, 30 parts of trimethylolpropane triglycidyl ether, and 10 parts of Evonik Degussa AEROSIL R202 hydrophobic fumed silica, add them to a mixing tank, stir evenly, and degas under vacuum; add 15 parts of Huntsman OMICURE DDA and 4 parts of OMICURE U-410M to the mixing tank in sequence, stir evenly, degas under vacuum, and discharge for later use.

[0020] Example 2

[0021] Add 605g of trimethylolpropane triglycidyl ether, 156.1g of bio-based FDCA, and 2.3g of triphenylphosphine to the reactor sequentially. Stir at 100-110℃ until the acid value is ≤0.2mgKOH / g, and discharge to obtain prepolymer A. Add 504.58g of HDI trimer and 179.3g of 3-aminopropyltrimethoxysilane to the reactor sequentially. Stir at 40℃ until the NCO group content is ≤12.28%. Continue to add 153.11g of (1-aminobutyl)phosphonic acid to the reactor. Stir at 40℃ for 0.5-1h until the NCO group content is ≤5% to obtain prepolymer B. Continue to add 763g of prepolymer A and 0.8g of BiCAT Z catalyst from Leading Chemicals (USA) to the reactor. React at 40-60℃ until the NCO groups disappear to obtain high-adhesion-strength bio-based epoxy resin B.

[0022] At room temperature, by weight, take 100 parts of high-adhesion bio-based epoxy resin B, 30 parts of neopentyl glycol diglycidyl ether, 20 parts of trimethylolpropane triglycidyl ether, and 10 parts of Evonik Degussa AEROSIL R202 hydrophobic fumed silica, add them to a mixing tank, stir evenly, and degas under vacuum; add 15 parts of Huntsman OMICURE DDA and 4 parts of OMICURE U-410M to the mixing tank in sequence, stir evenly, degas under vacuum, and discharge for later use.

[0023] Example 3

[0024] 3000g of castor oil triglycidyl ether XY966 from Anhui Xinyuan Technology Co., Ltd., 156.1g of bio-based FDCA, and 9.5g of triphenylphosphine were added sequentially to the reactor. The mixture was stirred at 100-110℃ until the acid value was ≤0.2mgKOH / g, and the product was discharged to obtain prepolymer A. 504.58g of HDI trimer and 255.4g of N-phenyl-3-aminopropyltrimethoxysilane were added sequentially to the reactor. The mixture was stirred at 40℃ until the NCO group content was ≤11.52%. 153.12g of 4-aminobutane-1-phosphoric acid was added to the reactor, and the mixture was stirred at 40℃ for 0.5-1h until the NCO group content was ≤5% to obtain prepolymer B. 3165.6g of prepolymer A and 2g of BiCAT Z catalyst from Leading Chemicals (USA) were added to the reactor, and the mixture was reacted at 40-60℃ until the NCO groups disappeared to obtain high-adhesion bio-based epoxy resin C.

[0025] At room temperature, by weight, take 100 parts of high-adhesion bio-based epoxy resin C, 25 parts of neopentyl glycol diglycidyl ether, 25 parts of trimethylolpropane triglycidyl ether, and 10 parts of Evonik Degussa AEROSIL R202 hydrophobic fumed silica, add them to a mixing tank, stir evenly, and degas under vacuum; add 13 parts of Huntsman OMICURE DDA and 4 parts of OMICURE U-410M to the mixing tank in sequence, stir evenly, degas under vacuum, and discharge for later use.

[0026] Comparative Example 1

[0027] At room temperature, by weight, take 100 parts of bisphenol A flexible epoxy resin EXA-4850-150, 20 parts of neopentyl glycol diglycidyl ether, 30 parts of trimethylolpropane triglycidyl ether, 5 parts of 3-aminopropyltriethoxysilane, and 10 parts of Evonik Degussa AEROSIL R202 hydrophobic fumed silica, add them to a stirred tank, stir evenly, and degas under vacuum; add 15 parts of Huntsman OMICURE DDA and 4 parts of OMICURE U-410M to the stirred tank in sequence, stir evenly, degas under vacuum, and discharge for later use.

[0028] Comparative Example 2

[0029] At room temperature, by weight, take 100 parts of naphthalene ring-containing high-hardness epoxy HP-4032SS, 40 parts of neopentyl glycol diglycidyl ether, 10 parts of trimethylolpropane triglycidyl ether, 5 parts of 3-aminopropyltriethoxysilane, and 10 parts of Evonik Degussa AEROSIL R202 hydrophobic fumed silica, add them to a stirred tank, stir evenly, and degas under vacuum; add 15 parts of Huntsman OMICURE DDA and 4 parts of OMICURE U-410M to the stirred tank in sequence, stir evenly, degas under vacuum, and discharge for later use.

[0030] The performance of the epoxy resin of the present invention was tested through the following experiments.

[0031] The bonding substrate is 3003Al, the bonding area is 12.5mm × 25mm, the adhesive layer thickness is 0.5mm, the curing process is 150℃ for 20min, and the testing speed is 50mm / min.

[0032] 1. Initial shear strength test.

[0033] 2. High and low temperature shock test: The sample was subjected to 200 cycles of (-40℃ / 30min- 85℃ / 30min), and then placed at room temperature for 24 hours for testing.

[0034] 3. High temperature and high humidity test: Place the sample in 85℃ and 85%RH for 1000h, and then place it at room temperature for 24h for testing.

[0035] 4. Dry heat test: ① Place the sample in 120℃ for 300 hours and test immediately.

[0036] ② Place the sample at 120℃ for 300 hours, then place it at room temperature for 24 hours before testing.

[0037] The test results are shown in Table 1.

[0038] Table 1. Comparison test results between the examples and the comparative examples.

[0039]

[0040] As can be seen from the above results, the high-adhesion bio-based epoxy resin of the present invention has higher adhesive strength, better resistance to high temperature and humidity, high and low temperature impact and dry heat, and the failure mode is the destruction of the adhesive layer itself, which makes it more reliable than commercially available resins.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for synthesizing a high-adhesion-strength bio-based epoxy resin, comprising the following steps: Step 1: Epoxy resin and bio-based furanyl dicarboxylic acid are reacted at 80-120℃ in a molar ratio of 2~2.1:1 under the action of catalyst a until the acid value is ≤0.2mgKOH / g, to obtain prepolymer A; Step 2: React aminosilane and diisocyanate trimer in an equimolar ratio at room temperature to 60°C until the NCO group reaches the designed value. Then add amino phosphate and react at room temperature to 60°C until the NCO group reaches the designed value to form prepolymer B. The third step involves adding prepolymer A to prepolymer B and reacting it at room temperature to 90°C under the action of catalyst b until the NCO groups disappear.

2. The method for synthesizing a high-adhesion-strength bio-based epoxy resin according to claim 1, characterized in that, The epoxy resin refers to a substance whose molecular structure contains at least two epoxy functional groups.

3. The method for synthesizing a high-adhesion-strength bio-based epoxy resin according to claim 1, characterized in that, The catalyst a comprises one of triphenylphosphine, tetrabutylammonium bromide, dimethylaniline, N,N-dimethylbenzylamine, triethylbenzylamine chloride, or triethylamine, and its addition amount is from one-thousandth to one-hundredth of the total mass of prepolymer A.

4. The method for synthesizing a high-adhesion-strength bio-based epoxy resin according to claim 1, characterized in that, The aminosilane includes one of N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and di(γ-trimethoxysilylpropyl)amine.

5. The method for synthesizing a high-adhesion-strength bio-based epoxy resin according to claim 1, characterized in that, The diisocyanate trimer includes HDI trimer and IPDI trimer.

6. The method for synthesizing a high-adhesion-strength bio-based epoxy resin according to claim 1, characterized in that, The aminophosphate ester includes one of aminomethylphosphonic acid, (1-aminobutyl)phosphonic acid, (1-aminooctyl)phosphonic acid, and 4-aminobutane-1-phosphonic acid.

7. The method for synthesizing a high-adhesion-strength bio-based epoxy resin according to claim 1, characterized in that, Catalyst b includes catalysts made of organotin, bismuth, zinc, or zirconium.

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