Epoxy crosslinking adhesive as well as preparation method and application thereof
By cross-linking reaction of epoxy soybean oil, dopamine and L-arginine, an epoxy cross-linking adhesive with high adhesion and mechanical properties was prepared, which solved the problem of difficult degradation and low adhesion ability of adhesives in the prior art, and achieved environmentally friendly and efficient adhesive applications.
Patent Information
- Application Number
- CN202311542476.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-17
- Publication Date
- 2025-03-07
AI Technical Summary
In the prior art, formaldehyde-based resin adhesives are difficult to degrade, and the pollution generated after use has a negative impact on the environment and health, and the adhesion ability of simple epoxy soybean oil adhesives is relatively low.
A epoxy crosslinking adhesive was prepared by mixing and heating epoxy soybean oil, dopamine and L-arginine to undergo crosslinking reaction. This adhesive improves adhesion ability through covalent cross-linking of catechol groups introduced by dopamine and the imine bond of L-arginine, and builds a cross-linking network through hydrogen bond interactions of hydroxyl, amine and carboxyl groups to improve mechanical properties and viscosity.
The high adhesion and mechanical properties of epoxy crosslinking adhesives are achieved. At the same time, due to the use of bio-based materials, the problem of difficult degradation and production of carcinogens in traditional adhesives is solved.
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Figure CN119570415A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of adhesives, and in particular to an epoxy cross-linked adhesive and a preparation method and application thereof. Background Art
[0002] In recent decades, there has been a growing demand for the development of environmentally friendly and renewable adhesives in order to find alternatives to formaldehyde-based resins, which come from non-renewable petrochemical products. In addition, the resulting composite wood panels release formaldehyde, which is a carcinogen that has a negative impact on human health and the environment. Therefore, the use of renewable biomass as an adhesive product has received extensive research attention. For example, the prior art discloses a single-component epoxy resin, epoxy curing material and application having an ester bond / imide bond dual dynamic cross-linking network. Although no carcinogenic formaldehyde is produced, the discarded resin adhesives have already caused a huge burden on the ecology, so there is an urgent need for a degradable bio-based adhesive that also takes into account mechanical properties.
[0003] Soybean oil is one of the most extensive sources of renewable organic matter. Epoxidized soybean oil can be prepared by a simple reaction with acid and hydrogen peroxide. Industrial production of epoxidized soybean oil has been achieved and applied in the field of plasticizing plastics. However, the product of the simple ring-opening reaction of epoxidized soybean oil has low adhesion. Based on this, it is necessary to provide an epoxidized soybean oil adhesive with strong adhesion. Summary of the invention
[0004] In view of this, the present invention provides an epoxy cross-linking adhesive and a preparation method and application thereof to solve the defects existing in the prior art.
[0005] In a first aspect, the present invention provides an epoxy cross-linked adhesive comprising the following raw materials in parts by weight: 80 to 120 parts of epoxy soybean oil, 30 to 60 parts of dopamine, and 30 to 40 parts of L-arginine.
[0006] Preferably, the epoxy cross-linked adhesive comprises the following raw materials in parts by weight: 100 parts of epoxy soybean oil, 50 parts of dopamine, and 30 parts of L-arginine.
[0007] In a second aspect, the present invention also provides a method for preparing the epoxy cross-linked adhesive, comprising the following steps:
[0008] After epoxy soybean oil, dopamine and L-arginine are mixed, heated, and cross-linked reaction occurs to obtain an epoxy cross-linked adhesive.
[0009] Preferably, in the preparation method of the epoxy cross-linked adhesive, dopamine is dissolved in an ethanol aqueous solution having a volume concentration of 93 to 97% to obtain a dopamine alcohol solution;
[0010] After epoxy soybean oil, dopamine alcohol solution and L-arginine are mixed, they are heated to cause a cross-linking reaction to obtain an epoxy cross-linking adhesive.
[0011] Preferably, in the preparation method of the epoxy cross-linked adhesive, epoxy soybean oil, dopamine alcohol solution and L-arginine are mixed, and then heated at 50-100° C. to cause a cross-linking reaction to obtain the epoxy cross-linked adhesive.
[0012] Preferably, in the preparation method of the epoxy cross-linked adhesive, epoxy soybean oil, dopamine alcohol solution and L-arginine are mixed, and then heated at 60-80° C. to cause a cross-linking reaction to obtain the epoxy cross-linked adhesive.
[0013] Preferably, in the preparation method of the epoxy cross-linked adhesive, the cross-linking reaction time is 6 to 36 hours.
[0014] Preferably, in the preparation method of the epoxy cross-linked adhesive, the cross-linking reaction time is 21 to 27 hours.
[0015] Preferably, in the method for preparing the epoxy cross-linked adhesive, in the step of dissolving dopamine in an ethanol aqueous solution having a volume concentration of 93 to 97%, the mass ratio of dopamine to the ethanol aqueous solution is (1 to 3):(1 to 10).
[0016] In a third aspect, the present invention also provides an application of the epoxy cross-linking adhesive or the epoxy cross-linking adhesive prepared by the preparation method in metal plate and wood processing.
[0017] The present invention has the following beneficial effects compared with the prior art:
[0018] 1. The epoxy cross-linked adhesive of the present invention utilizes the epoxy groups of the epoxy soybean oil to undergo a ring-opening reaction with the amine and carboxyl groups on the cross-linking agent to increase the polar functional groups of the epoxy soybean oil; a cross-linking network can be constructed through the hydrogen bond interaction between the carboxyl, hydroxyl and carbonyl groups to improve the mechanical properties and viscosity of the adhesive. More importantly, the ring-opening reaction on the epoxy soybean oil can increase the number of ester groups of the epoxy soybean oil, thereby improving the hydrophobicity of the adhesive;
[0019] 2. Traditional adhesives will cause pollution. Resin adhesives cannot be degraded after use and can only be processed by crushing. This may cause soil or marine toxicity problems. Formaldehyde-based resins will also produce carcinogen formaldehyde. In the present invention, because the materials used are all bio-based materials, the problem that traditional adhesives are difficult to degrade and produce carcinogenic formaldehyde can be solved; the epoxy cross-linked adhesive of the present invention contains catechol groups, imine bonds, ester bonds, amine groups, hydroxyl groups, carboxyl groups and hydrophobic chains. Not only does it use biomimetic means to introduce catechol groups, but the imine bonds can also undergo Schiff base reactions to produce covalent cross-linking to improve adhesion; and the hydrophobic chains on the epoxy soybean oil and the ester groups added after ring opening can construct hydrophobic interactions; in addition, the hydroxyl groups, amine groups and carboxyl groups rich in the adhesive can also provide hydrogen bonds; the adhesive of the present invention improves adhesion performance through mutual promotion of multiple mechanisms; the preparation method of the epoxy cross-linked adhesive of the present invention is simple, this bio-based adhesive can be prepared by simple mixing and heating, the reaction device is simple, and it is expected to be further promoted and industrialized. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0021] Figure 1 The shear strength change of the adhesive prepared in Example 3 of the present invention after underwater immersion. DETAILED DESCRIPTION
[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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.
[0023] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered ranges, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.
[0024] The embodiment of the present application provides an epoxy cross-linked adhesive, comprising the following raw materials in parts by weight: 80 to 120 parts of epoxy soybean oil, 30 to 60 parts of dopamine, and 30 to 40 parts of L-arginine.
[0025] It should be noted that the epoxy cross-linked adhesive of the present invention comprises epoxy soybean oil, dopamine, and L-arginine, wherein the epoxy soybean oil is prepared by reacting soybean oil with acid and hydrogen peroxide, and the chemical formula is C 57 H 98 O 12 , the chemical structure is as follows:
[0026]
[0027] Dopamine is used as a cross-linking agent. It contains catechol groups and amine groups. The chemical formula of dopamine is: C8H 11 O2N, the chemical structure of dopamine is shown below:
[0028]
[0029] L-arginine (i.e. 2-amino-5-guanidine valeric acid) is used as a cross-linking agent. L-arginine contains an imino group, a carboxyl group, and an amine group. The chemical formula of L-arginine is C6H 14 The chemical structure of N4O2, L-arginine is as follows:
[0030]
[0031] In some embodiments, the epoxy cross-linked adhesive comprises the following raw materials in parts by weight: 100 parts of epoxy soybean oil, 30-60 parts of dopamine, and 30-40 parts of L-arginine.
[0032] In some embodiments, the epoxy cross-linked adhesive comprises the following raw materials in parts by weight: 100 parts of epoxy soybean oil, 50 parts of dopamine, and 30 parts of L-arginine.
[0033] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned epoxy cross-linking adhesive, comprising the following steps:
[0034] After epoxy soybean oil, dopamine and L-arginine are mixed, heated, and cross-linked reaction occurs to obtain an epoxy cross-linked adhesive.
[0035] The preparation method of the epoxy cross-linked adhesive of the present invention uses epoxy soybean oil as a raw material, introduces dopamine, reacts the amine group on the dopamine with the epoxy group on the epoxy soybean oil, introduces a catechol group, and converts the epoxy soybean oil into a strong adhesive with catechol properties through dopamine. Based on the strong adhesion ability of the catechol group and the covalent cross-linking provided by the imine bond, a green and environmentally friendly epoxy cross-linked adhesive is prepared; epoxy soybean oil is a renewable organic compound, and each epoxy soybean oil molecule has The invention contains at least 5 epoxy groups, which can be ring-opened by nucleophilic addition reaction with the carboxyl group and the amine group on L-arginine (2-amino-5-guanidinopentanoic acid) and the amine group on dopamine, thereby introducing a catechol group and an imine bond on the epoxy soybean oil molecule; the invention utilizes the epoxy group of the epoxy soybean oil to undergo a ring-opening reaction with the amine group and the carboxyl group on the cross-linking agent, thereby increasing the polar functional groups of the epoxy soybean oil; a cross-linking network can be constructed by hydrogen bonding interaction between the carboxyl group, the hydroxyl group and the carbonyl group, thereby improving the mechanical properties and viscosity of the adhesive. More importantly, the ring-opening reaction on the epoxidized soybean oil can increase the number of ester groups of the epoxidized soybean oil, thereby improving the hydrophobicity of the adhesive; at the same time, the cross-linking agent L-arginine contains imino, carboxyl and amine groups, and the imino can react with the carbonyl group to form a covalent bond, while the introduction of carboxyl and amine groups can not only react with the epoxy group, but also increase the hydrogen bond interaction; the multifunctional L-arginine increases the degree of cross-linking and introduces imino groups to improve the adhesion ability; the adhesive of the present invention uses epoxidized soybean oil as the main body, and uses multiple epoxy groups on the epoxidized soybean oil to react with carboxyl and amine groups to form a cross-linked structure. At the same time, the hydroxyl and carboxyl groups contained in dopamine and L-arginine can also construct a hydrogen bond cross-linking network, thereby increasing the degree of cross-linking and further improving the adhesion ability of the adhesive. And through the means of biomimetic, the ring-opening reaction between the amino group on dopamine and the epoxy group on the epoxy soybean oil is utilized to introduce the catechol group into the adhesive, and the imino bond is introduced for covalent cross-linking to further improve the adhesion ability. The adhesive of the present invention has good adhesion to metals such as aluminum and steel and wood. And all the components of the adhesive are biomass, and the cost is low. And this adhesive is easy to make, and it can be prepared by simple mixing and heating. The components used in the present invention are all bio-based environmentally friendly materials, and the cost is low. It is prepared by simple blending of three components, and it is expected to achieve large-scale production.
[0036] In some embodiments, dopamine is dissolved in an ethanol aqueous solution having a volume concentration of 93-97% to obtain a dopamine alcohol solution;
[0037] After epoxy soybean oil, dopamine alcohol solution and L-arginine are mixed, they are heated to cause a cross-linking reaction to obtain an epoxy cross-linking adhesive.
[0038] In some embodiments, epoxy soybean oil, dopamine alcohol solution, and L-arginine are mixed and heated at 50-100° C. to cause a cross-linking reaction to obtain an epoxy cross-linked adhesive.
[0039] In some embodiments, epoxy soybean oil, dopamine alcohol solution, and L-arginine are mixed and heated at 60-80° C. to cause a cross-linking reaction to obtain an epoxy cross-linked adhesive.
[0040] In some embodiments, the cross-linking reaction time is 6 to 36 hours.
[0041] In some embodiments, the cross-linking reaction time is 21 to 27 hours.
[0042] In some embodiments, in the step of dissolving dopamine in an ethanol aqueous solution with a volume concentration of 93-97%, the mass ratio of dopamine to the ethanol aqueous solution is (1-3):(1-10).
[0043] Compared with the prior art, the preparation method of the epoxy cross-linked adhesive of the present invention has the following advantages:
[0044] 1) Traditional adhesives can cause pollution. Resin adhesives cannot be degraded after use and can only be processed by crushing. This may cause soil or marine toxicity problems. Formaldehyde-based resins also produce carcinogen formaldehyde. In the present invention, because the materials used are all bio-based materials, the problem of traditional adhesives being difficult to degrade and producing carcinogenic formaldehyde can be solved.
[0045] 2) The epoxy cross-linked adhesive of the present invention contains catechol groups, imine bonds, ester bonds, amine groups, hydroxyl groups, carboxyl groups and hydrophobic chains. Not only does it use bionics to introduce catechol groups, but the imine bonds can also undergo Schiff base reactions to produce covalent crosslinks to improve adhesion. In addition, the hydrophobic chains on the epoxidized soybean oil and the ester groups added after ring opening can construct hydrophobic interactions. In addition, the hydroxyl groups, amine groups and carboxyl groups rich in the adhesive can also provide hydrogen bonds. The adhesive of the present invention improves adhesion performance through the mutual promotion of multiple mechanisms.
[0046] 3) The preparation method of the epoxy cross-linked adhesive of the present invention is simple. This bio-based adhesive can be prepared by simple mixing and heating, and the reaction device is simple, which is expected to be further promoted and industrialized.
[0047] Based on the same inventive concept, the invention also provides an application of the epoxy cross-linking adhesive or the epoxy cross-linking adhesive prepared by the preparation method in metal plate and wood processing.
[0048] The following further describes the epoxy cross-linked adhesive and preparation method of the present application with specific examples. This section further describes the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.
[0049] Example 1
[0050] The embodiment of the present application provides an epoxy cross-linking adhesive, comprising the following raw materials in parts by weight: 100 parts of epoxy soybean oil, 30 parts of dopamine, and 30 parts of L-arginine.
[0051] The preparation method of the above-mentioned epoxy cross-linked adhesive comprises the following steps:
[0052] S1, dissolving 30 parts by weight of dopamine in 90 parts by weight of an ethanol aqueous solution having a volume concentration of 95% to obtain a dopamine alcohol solution;
[0053] S2. At room temperature, take 100 parts by weight of epoxy soybean oil and heat it to 70°C, add the dopamine alcohol solution in S1, and then add 30 parts by weight of L-arginine, maintain 70°C, and stir for 24 hours to allow the carboxyl group on L-arginine and the amine group on dopamine to undergo a ring-opening reaction with the epoxy soybean oil to obtain a bio-based, green and environmentally friendly epoxy cross-linking adhesive.
[0054] Example 2
[0055] The embodiment of the present application provides an epoxy cross-linking adhesive, comprising the following raw materials in parts by weight: 100 parts of epoxy soybean oil, 40 parts of dopamine, and 30 parts of L-arginine.
[0056] The preparation method of the above-mentioned epoxy cross-linked adhesive comprises the following steps:
[0057] S1, dissolving 40 parts by weight of dopamine in 90 parts by weight of an ethanol aqueous solution having a volume concentration of 95% to obtain a dopamine alcohol solution;
[0058] S2. At room temperature, take 100 parts by weight of epoxy soybean oil and heat it to 70°C, add the dopamine alcohol solution in S1, and then add 30 parts by weight of L-arginine, maintain 70°C, and stir for 24 hours to allow the carboxyl group on L-arginine and the amine group on dopamine to undergo a ring-opening reaction with the epoxy soybean oil to obtain a bio-based, green and environmentally friendly epoxy cross-linking adhesive.
[0059] Example 3
[0060] The embodiment of the present application provides an epoxy cross-linking adhesive, comprising the following raw materials in parts by weight: 100 parts of epoxy soybean oil, 50 parts of dopamine, and 30 parts of L-arginine.
[0061] The preparation method of the above-mentioned epoxy cross-linked adhesive comprises the following steps:
[0062] S1, dissolving 50 parts by weight of dopamine in 90 parts by weight of an ethanol aqueous solution having a volume concentration of 95% to obtain a dopamine alcohol solution;
[0063] S2. At room temperature, take 100 parts by weight of epoxy soybean oil and heat it to 70°C, add the dopamine alcohol solution in S1, and then add 30 parts by weight of L-arginine, maintain 70°C, and stir for 24 hours to allow the carboxyl group on L-arginine and the amine group on dopamine to undergo a ring-opening reaction with the epoxy soybean oil to obtain a bio-based, green and environmentally friendly epoxy cross-linking adhesive.
[0064] Example 4
[0065] The embodiment of the present application provides an epoxy cross-linking adhesive, comprising the following raw materials in parts by weight: 100 parts of epoxy soybean oil, 60 parts of dopamine, and 30 parts of L-arginine.
[0066] The preparation method of the above-mentioned epoxy cross-linked adhesive comprises the following steps:
[0067] S1, dissolving 60 parts by weight of dopamine in 90 parts by weight of an ethanol aqueous solution having a volume concentration of 95% to obtain a dopamine alcohol solution;
[0068] S2. At room temperature, take 100 parts by weight of epoxy soybean oil and heat it to 70°C, add the dopamine alcohol solution in S1, and then add 30 parts by weight of L-arginine, maintain 70°C, and stir for 24 hours to allow the carboxyl group on L-arginine and the amine group on dopamine to undergo a ring-opening reaction with the epoxy soybean oil to obtain a bio-based, green and environmentally friendly epoxy cross-linking adhesive.
[0069] Example 5
[0070] The embodiment of the present application provides an epoxy cross-linking adhesive, comprising the following raw materials in parts by weight: 100 parts of epoxy soybean oil, 30 parts of dopamine, and 40 parts of L-arginine.
[0071] The preparation method of the above-mentioned epoxy cross-linked adhesive comprises the following steps:
[0072] S1, dissolving 30 parts by weight of dopamine in 90 parts by weight of an ethanol aqueous solution having a volume concentration of 95% to obtain a dopamine alcohol solution;
[0073] S2. At room temperature, take 100 parts by weight of epoxy soybean oil and heat it to 70°C, add the dopamine alcohol solution in S1, and then add 40 parts by weight of L-arginine, maintain 70°C, and stir for 24 hours to allow the carboxyl group on L-arginine and the amine group on dopamine to undergo a ring-opening reaction with the epoxy soybean oil to obtain a bio-based, green and environmentally friendly epoxy cross-linking adhesive.
[0074] Example 6
[0075] The embodiment of the present application provides an epoxy cross-linking adhesive, comprising the following raw materials in parts by weight: 100 parts of epoxy soybean oil, 40 parts of dopamine, and 40 parts of L-arginine.
[0076] The preparation method of the above-mentioned epoxy cross-linked adhesive comprises the following steps:
[0077] S1, dissolving 40 parts by weight of dopamine in 90 parts by weight of an ethanol aqueous solution having a volume concentration of 95% to obtain a dopamine alcohol solution;
[0078] S2. At room temperature, take 100 parts by weight of epoxy soybean oil and heat it to 70°C, add the dopamine alcohol solution in S1, and then add 40 parts by weight of L-arginine, maintain 70°C, and stir for 24 hours to allow the carboxyl group on L-arginine and the amine group on dopamine to undergo a ring-opening reaction with the epoxy soybean oil to obtain a bio-based, green and environmentally friendly epoxy cross-linking adhesive.
[0079] Example 7
[0080] The embodiment of the present application provides an epoxy cross-linking adhesive, comprising the following raw materials in parts by weight: 100 parts of epoxy soybean oil, 50 parts of dopamine, and 40 parts of L-arginine.
[0081] The preparation method of the above-mentioned epoxy cross-linked adhesive comprises the following steps:
[0082] S1, dissolving 50 parts by weight of dopamine in 90 parts by weight of an ethanol aqueous solution having a volume concentration of 95% to obtain a dopamine alcohol solution;
[0083] S2. At room temperature, take 100 parts by weight of epoxy soybean oil and heat it to 70°C, add the dopamine alcohol solution in S1, and then add 40 parts by weight of L-arginine, maintain 70°C, and stir for 24 hours to allow the carboxyl group on L-arginine and the amine group on dopamine to undergo a ring-opening reaction with the epoxy soybean oil to obtain a bio-based, green and environmentally friendly epoxy cross-linking adhesive.
[0084] Example 8
[0085] The embodiment of the present application provides an epoxy cross-linking adhesive, comprising the following raw materials in parts by weight: 100 parts of epoxy soybean oil, 60 parts of dopamine, and 40 parts of L-arginine.
[0086] The preparation method of the above-mentioned epoxy cross-linked adhesive comprises the following steps:
[0087] S1, dissolving 60 parts by weight of dopamine in 90 parts by weight of an ethanol aqueous solution having a volume concentration of 95% to obtain a dopamine alcohol solution;
[0088] S2. At room temperature, take 100 parts by weight of epoxy soybean oil and heat it to 70°C, add the dopamine alcohol solution in S1, and then add 40 parts by weight of L-arginine, maintain 70°C, and stir for 24 hours to allow the carboxyl group on L-arginine and the amine group on dopamine to undergo a ring-opening reaction with the epoxy soybean oil to obtain a bio-based, green and environmentally friendly epoxy cross-linking adhesive.
[0089] Comparative Example 1
[0090] This comparative example provides an epoxy cross-linked adhesive, comprising the following raw materials in parts by weight: 100 parts of epoxy soybean oil and 40 parts of L-arginine.
[0091] The preparation method of the above-mentioned epoxy cross-linked adhesive comprises the following steps:
[0092] S1. At room temperature, take 100 parts by weight of epoxy soybean oil and heat it to 70°C, add 40 parts by weight of L-arginine, maintain 70°C, and stir for 24 hours to obtain an epoxy cross-linked adhesive.
[0093] Performance Testing
[0094] Tensile strength test
[0095] A tensile test was performed on the adhesives prepared in Examples 1-8 and Comparative Example 1 at room temperature using a universal tester to detect the tensile strength and elongation at break of the samples, wherein the sample size was 60×10 mm (length×width), the initial test distance between the two fixtures was 20 mm, and the sample was tested at a loading speed of 50 mm / min. The test results are shown in Table 1 below.
[0096] Table 1 - Tensile strength and elongation at break of adhesives in Examples 1-8 and Comparative Example 1
[0097] Example Tensile strength(MPa) Elongation at break (%) Example 1 7.6 140 Example 2 8.1 145 Example 3 8.7 151 Example 4 8.2 146 Example 5 7.7 138 Example 6 8.0 144 Example 7 7.6 137 Example 8 7.3 133 Comparative Example 1 1.2 63
[0098] As can be seen from Table 1, the tensile strength and elongation at break of the adhesive prepared in Comparative Example 1 are much lower than those of Examples 1 to 8. The tensile strength of the adhesive in Comparative Example 1 is only 1.2 MPa, while the tensile strength of the adhesive prepared in Example 3 is as high as 8.7 MPa, indicating that the bonding strength of the adhesives in Examples 1 to 8 is significantly better than that in Comparative Example 1. The elongation at break in Example 3 is also the highest, reaching 151%. With the increase in the amount of dopamine added, the tensile strength gradually decreases after the amount added reaches a certain level. This is because excessive dopamine causes dopamine to occupy a large number of epoxy sites, making it difficult for L-arginine to cross-link, reducing the degree of cross-linking of the entire system, thereby reducing the performance of the adhesive.
[0099] Shear strength test
[0100] Take 0.4mL of the adhesive prepared in Examples 1 to 8 and Comparative Example 1 and evenly apply it on a PVC (polyvinyl chloride) plate and polished steel, and control the thickness of the adhesive layer to 0.2mm. Take out the other side of the substrate and fix it with it, and the overlap size is 20mm×25mm. Place the bonded sample in a 160℃ oven and dry it for 6h, while applying a pressure of 0.4MPa. After drying, cool it at room temperature, use a tensile machine to test the shear strength, and the tensile rate is 5mm / min to obtain the shear strength. The results are shown in Table 2.
[0101] Table 2 - Shear strength of adhesives in Examples 1 to 8 and Comparative Example 1
[0102]
[0103] It can be seen from Table 2 that all adhesives have greater shear strength to polished steel. The adhesives prepared in Examples 1 to 4 have greater shear strength than those in Examples 5 to 8 and Comparative Example 1.
[0104] Underwater adhesion test
[0105] Take 0.4 mL of the adhesive prepared in Example 3 and evenly apply it on the polished steel, and control the thickness of the adhesive layer to 0.2 mm. Take out the other side of the substrate and fix it to it, with the overlap size of 20 mm × 25 mm. Place the bonded sample in a 160°C oven and dry it for 6 hours, while applying a pressure of 0.4 MPa. After drying, cool it at room temperature and soak it in water for different times. Use a stretching machine to test the shear strength of samples with different immersion times, with a stretching rate of 5 mm / min, to obtain the shear strength. The results are as follows Figure 1 shown.
[0106] from Figure 1 It can be seen that the initial shear strength of the adhesive in Example 3 is 8.5 MPa. After immersion for 1h, 6h, 12h, 18h, 24h, and 168h, the shear strengths of the adhesive are 8.3MPa, 8.1MPa, 7.6MPa, 7MPa, 6.6MPa, and 4.3MPa, respectively. As the immersion time of the adhesive in water increases, the shear strength gradually decreases, but after 24h, it can still maintain about 78% of the adhesion performance. The gradual decrease in adhesion performance in water also indirectly reflects its degradability.
[0107] 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 in the protection scope of the present invention.
Claims
1. An epoxy cross-linking adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: 80 to 120 parts of epoxidized soybean oil, 30 to 60 parts of dopamine and 30 to 40 parts of L-arginine.
2. The epoxy cross-linking adhesive according to claim 1, characterized in that: The method comprises the following raw materials in parts by weight: 100 parts of epoxidized soybean oil, 50 parts of dopamine and 30 parts of L-arginine.
3. A method for preparing an epoxy cross-linked adhesive as claimed in any one of claims 1 to 2, characterized in that: The following steps are involved: After epoxy soybean oil, dopamine and L-arginine are mixed, heated, and cross-linked reaction occurs to obtain an epoxy cross-linked adhesive.
4. The method for preparing the epoxy cross-linked adhesive according to claim 3, characterized in that: Dissolving dopamine in an ethanol aqueous solution having a volume concentration of 93-97% to obtain a dopamine alcohol solution; After epoxy soybean oil, dopamine alcohol solution and L-arginine are mixed, they are heated to cause a cross-linking reaction to obtain an epoxy cross-linking adhesive.
5. The method for preparing the epoxy cross-linked adhesive according to claim 4, characterized in that: After mixing epoxy soybean oil, dopamine alcohol solution and L-arginine, the mixture is heated at 50-100° C. to cause a cross-linking reaction, thereby obtaining an epoxy cross-linking adhesive.
6. The method for preparing the epoxy cross-linked adhesive according to claim 5, characterized in that: After mixing epoxy soybean oil, dopamine alcohol solution and L-arginine, the mixture is heated at 60-80°C to cause a cross-linking reaction, thereby obtaining an epoxy cross-linking adhesive.
7. The method for preparing the epoxy cross-linked adhesive according to claim 4, characterized in that: The cross-linking reaction time is 6 to 36 hours.
8. The method for preparing the epoxy cross-linked adhesive according to claim 7, characterized in that: The cross-linking reaction time is 21 to 27 hours.
9. The method for preparing the epoxy cross-linked adhesive according to claim 4, characterized in that: In the step of dissolving dopamine in an ethanol aqueous solution with a volume concentration of 93-97%, the mass ratio of dopamine to the ethanol aqueous solution is (1-3):(1-10).
10. Use of the epoxy cross-linking adhesive according to any one of claims 1 to 2 or the epoxy cross-linking adhesive prepared by the preparation method according to any one of claims 3 to 9 in metal plate and wood processing.