A one-component epoxy structural adhesive and its preparation method and application

Abstract

The invention provides a one-component epoxy structural adhesive and a preparation method and application thereof. The one-component epoxy structural adhesive comprises specific portions of bisphenol A epoxy resin, polyurethane modified epoxy resin, core-shell rubber toughening agent, reactive diluent, dicyandiamide, hydrazide complex, imidazole adduct and urea-based accelerator. The two epoxy resins are selected for matching, and two curing agents, dicyandiamide and hydrazide complex, are used for coordination, and imidazole adduct and urea-based accelerator are used for assistance, so that the one-component epoxy structural adhesive not only has a lower curing temperature, but also has excellent storage stability, can be stably stored at room temperature for up to 6 months, and the cured product obtained after curing has high strength and high toughness.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to a single-component epoxy structural adhesive and a preparation method and application thereof. Background Art

[0002] Lightweight integration of automobiles will become the key development direction of future automobiles. The use of adhesives to replace the use of traditional rivets will effectively reduce the weight of the automobile body and the integration process, which will in turn drive the further application of adhesives in the field of automobile structural bonding. Epoxy resin structural adhesives have good bonding properties, thermal stability, good corrosion resistance and high mechanical strength. They are widely used in structural bonding of plates. When used in combination with processes such as spot welding, they can greatly improve the fatigue strength, stiffness and impact resistance of structural parts. Among them, single-component epoxy structural adhesives are the most widely used adhesives for automobile structural bonding, and their volume will also increase rapidly in the next few years.

[0003] One-component epoxy structural adhesives are divided into moisture-curing type and heat-curing type; according to the curing temperature, they can be roughly divided into low-temperature (≤80℃) curing type one-component epoxy, medium-temperature (80-160℃) curing type one-component epoxy and high-temperature (≥160℃) curing type one-component epoxy; among them, the high-temperature curing type one-component epoxy has a higher curing temperature, resulting in higher energy consumption, while the low-temperature curing type one-component epoxy has poor mechanical properties and is mainly used for packaging sealing and structural bonding in industries such as electronic printed circuits and medical devices.

[0004] CN112646523A discloses a high-performance medium-temperature curing single-component epoxy structural adhesive, which comprises the following components in parts by weight: 100 parts of epoxy resin; 0 to 30 parts of diluent; 10 to 15 parts of latent curing agent; 30 to 40 parts of toughening agent; 3.7 parts of accelerator; 3 to 7 parts of thixotropic reinforcing agent; 3 to 5 parts of coupling agent; and 20 to 30 parts of filler. The invention also provides a method for preparing the structural adhesive, comprising the following steps: (1) taking epoxy resin, diluent, toughening agent, filler, and thixotropic reinforcing agent in proportion and stirring evenly; (2) vacuum dehydrating in an environment of >100°C, then cooling to room temperature, taking latent curing agent, accelerator, and coupling agent in proportion, stirring evenly in an environment of <40°C, vacuum degassing, and obtaining a structural adhesive; the structural adhesive provided by the invention has high toughness, high bonding strength, and short-term high temperature resistance (up to 280°C), which can effectively meet the market demand for the use of single-component epoxy structural adhesives; however, the room temperature storage stability of the epoxy structural adhesive provided by the invention still needs to be improved.

[0005] Therefore, developing a single-component epoxy structural adhesive with high strength and excellent storage stability at room temperature is still a technical problem that urgently needs to be solved in this field. Summary of the invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a one-component epoxy structural adhesive and a preparation method and application thereof. By selecting two epoxy resins for combination, and using two curing agents, dicyandiamide and hydrazide complex, and assisting with imidazole adducts and urea-based accelerators, not only the curing temperature of the one-component epoxy structural adhesive is effectively reduced, but also its storage stability is effectively improved, so that it can be stably stored at room temperature for up to 6 months. At the same time, the cured product obtained after curing has high strength and high toughness.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a one-component epoxy structural adhesive, wherein the one-component epoxy structural adhesive comprises the following components in parts by weight:

[0009]

[0010]

[0011] Wherein, the usage amount of the bisphenol A epoxy resin can be 12 parts by weight, 14 parts by weight, 16 parts by weight, 18 parts by weight, 20 parts by weight, 22 parts by weight, 24 parts by weight, 26 parts by weight or 28 parts by weight, etc.

[0012] The polyurethane modified epoxy resin may be used in an amount of 7 parts by weight, 9 parts by weight, 11 parts by weight, 13 parts by weight, 15 parts by weight, 17 parts by weight or 19 parts by weight.

[0013] The amount of the core-shell rubber toughening agent can be 13 parts by weight, 16 parts by weight, 19 parts by weight, 21 parts by weight, 24 parts by weight or 27 parts by weight.

[0014] The amount of the active diluent can be 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight or 9 parts by weight.

[0015] The usage of the dicyandiamide can be 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight or 4.5 parts by weight, etc.

[0016] The amount of the hydrazide complex can be 0.7 parts by weight, 0.9 parts by weight, 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, etc.

[0017] The amount of the imidazole adduct can be 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight or 0.9 parts by weight.

[0018] The urea-based accelerator may be used in an amount of 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, or 0.9 parts by weight.

[0019] The raw materials of the one-component epoxy structural adhesive provided by the present invention include two epoxy resins, namely, bisphenol A epoxy resin and polyurethane modified epoxy resin, wherein the bisphenol A epoxy resin helps to improve the strength of the colloid and the bonding performance to the substrate, and the polyurethane modified epoxy resin helps to provide the flexibility of the colloid and further synergistically improve the strength of the colloid, and the addition of a core-shell rubber toughening agent helps to further improve the impact peeling resistance and low-temperature performance of the colloid; at the same time, two curing agents with different curing temperatures, namely, dicyandiamide and hydrazide complex, are selected for matching, and the different curing temperatures of the two are utilized, and the assistance of imidazole adducts and urea-based accelerators is assisted, and the different activation temperatures of the two are utilized, as well as the soft-hard matching, and under the premise of effectively reducing the curing activation temperature of the one-component epoxy structural adhesive, its room temperature storage stability is fully improved, so that it can be stably stored for 6 months at room temperature, and at the same time, it is ensured that the cured product obtained after curing has high strength and high toughness.

[0020] Preferably, the core material of the core-shell rubber toughener comprises a copolymer of a diene and a monoene.

[0021] Preferably, the shell material of the core-shell rubber toughener comprises epoxy-functionalized alkyl methacrylate homopolymer and / or copolymer.

[0022] Preferably, the reactive diluent comprises a bifunctional reactive diluent.

[0023] Preferably, the bifunctional reactive diluent comprises 1,4-butanediol diglycidyl ether and / or 1,6-hexanediol diglycidyl ether.

[0024] In the present invention, there is no special requirement for the type of the hydrazide complex, and the hydrazide complex AH-123 of Ajinomoto is preferred.

[0025] Likewise, the present invention does not impose any special requirements on the type of the imidazole adduct, and preferably it is Ajinomoto PN-50 or PN-40.

[0026] Preferably, the urea-based accelerator includes a monourea accelerator and / or a diurea accelerator; wherein the diurea accelerator is preferably the diurea accelerator 5050 of Hailuohe New Materials.

[0027] Preferably, the one-component epoxy structural adhesive further comprises liquid nitrile rubber modified epoxy resin, and the liquid nitrile rubber modified epoxy resin helps to improve the peel strength of the colloid and further synergistically improve the toughness of the colloid.

[0028] Preferably, the amount of liquid nitrile rubber modified epoxy resin in the one-component epoxy structural adhesive is not more than 20 parts by weight, for example, 18 parts by weight, 16 parts by weight, 14 parts by weight, 12 parts by weight, 10 parts by weight, 8 parts by weight, 6 parts by weight, 4 parts by weight or 2 parts by weight, etc.

[0029] Preferably, the liquid nitrile rubber modified epoxy resin is a butadiene-acrylonitrile elastomer grafted modified bisphenol A epoxy resin.

[0030] Preferably, the one-component epoxy structural adhesive further comprises a filler and / or a thixotropic agent.

[0031] Preferably, the content of filler in the one-component epoxy structural adhesive is 15 to 20 parts by weight, for example, 15.5 parts by weight, 16 parts by weight, 16.5 parts by weight, 17 parts by weight, 17.5 parts by weight, 18 parts by weight, 18.5 parts by weight, 19 parts by weight or 19.5 parts by weight, etc.

[0032] Preferably, the filler is an inorganic filler, for example, heavy calcium and / or microsilica powder may be selected.

[0033] Preferably, the content of the thixotropic agent in the one-component epoxy structural adhesive is 3 to 6 parts by weight, for example, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight or 5.5 parts by weight.

[0034] Preferably, the thixotropic agent comprises white carbon black.

[0035] In a second aspect, the present invention provides a method for preparing the one-component epoxy structural adhesive as described in the first aspect, the preparation method comprising: mixing bisphenol A epoxy resin, polyurethane modified epoxy resin, core-shell rubber toughening agent, reactive diluent and optional liquid nitrile rubber modified epoxy resin, adding optional filler and optional thixotropic agent to mix, and then adding dicyandiamide, hydrazide complex, imidazole adduct and urea-based accelerator to mix to obtain the one-component epoxy structural adhesive.

[0036] Preferably, the preparation method specifically comprises: at room temperature, mixing bisphenol A epoxy resin, polyurethane modified epoxy resin, core-shell rubber toughening agent, reactive diluent and optionally liquid nitrile rubber modified epoxy resin at a stirring speed of 300 to 450 rpm (e.g., 320 rpm, 340 rpm, 360 rpm, 380 rpm, 400 rpm, 420 rpm or 440 rpm, etc.) for 0.2 to 1 h (e.g., 0.3 h, 0.4 h, 0.5 h, 0.6 h, 0.7 h, 0.8 h or 0.9 h, etc.), adding optional filler and optional thixotropic agent at ≤-0.1 MPa (e.g., -0.2 MPa, -0.3 MPa, -0.4 MPa or -0.5 MPa, etc.) and a speed of 300 to 450 rpm (e.g., 320 rpm, 340 rpm, 360 rpm, 380 rpm, 400 rpm, 420 rpm or 440 rpm, etc.) under stirring conditions for 0.2 to 1 h (e.g., 0.3 h, 0.4 h, 0.5 h, 0.6 h, 0.7 h, 0.8 h or 0.9 h, etc.), m, 400rpm, 420rpm or 440rpm, etc.), and mixed for 0.2 to 1h (for example, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h or 0.9h, etc.), and then dicyandiamide, hydrazide complex, imidazole adduct and urea-based accelerator are added and mixed for 0.2 to 1h (for example, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h or 0.9h, etc.) under the conditions of ≤-0.1MPa (for example, -0.2MPa, -0.3MPa, -0.4MPa or -0.5MPa, etc.) and a rotation speed of 100 to 120rpm (for example, 102rpm, 104rpm, 106rpm, 108rpm, 110rpm, 112rpm, 114rpm, 116rpm or 118rpm, etc.) to obtain the one-component epoxy structural adhesive.

[0037] In a third aspect, the present invention provides a use of the one-component epoxy structure according to the first aspect, wherein the use includes bonding for automobile body structures.

[0038] Preferably, the vehicle body comprises a steel vehicle body.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The single-component epoxy structural adhesive provided by the present invention comprises specific proportions of bisphenol A epoxy resin, polyurethane modified epoxy resin, core-shell rubber toughening agent, active diluent, dicyandiamide, hydrazide complex, imidazole adduct and urea-based accelerator. By selecting the above two epoxy resins for matching, and using two curing agents, dicyandiamide and hydrazide complex, for coordination, and assisting with imidazole adduct and urea-based accelerator, the single-component epoxy structural adhesive not only has a lower curing temperature, but also has excellent storage stability, can be stably stored at room temperature for up to 6 months, and the cured product obtained after curing has high strength and high toughness. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0042] Unless otherwise specified, the raw materials involved in the specific embodiments of the present invention are all conventional materials in the art and can be purchased commercially; specifically, some of the raw material information involved in the following specific embodiments is as follows:

[0043] Bisphenol A epoxy resin: purchased from Nan Ya, brand number 128;

[0044] Polyurethane modified epoxy resin: purchased from Shanghai Luohe High-tech Materials, brand EPU-133;

[0045] Liquid nitrile rubber modified epoxy resin: purchased from Evonik, brand name Albipox2000;

[0046] Core-shell rubber toughener: the core material includes a copolymer of a diene and a monoolefin, and the shell material includes an epoxy-functionalized alkyl methacrylate homopolymer, purchased from Kaneka, with the brand name MX-153;

[0047] Active diluent: purchased from Anhui Xinyuan, brand name XY-632;

[0048] Dicyandiamide: purchased from Evonik, brand: 1400B;

[0049] Hydrazide complex: purchased from Ajinomoto, brand name AH-123;

[0050] Urea-based accelerator: purchased from Shanghai Luhe High-tech Materials, brand 5050;

[0051] Imidazole accelerator: purchased from Ajinomoto, brand name PN-40.

[0052] Examples 1 to 5 and Comparative Examples 1 to 5

[0053] Examples 1 to 5 respectively provide a one-component epoxy structural adhesive, specifically including the components shown in Table 1, wherein the amount of each component is "parts by weight";

[0054] Table 1

[0055]

[0056] Comparative Examples 1 to 5 respectively provide a one-component epoxy structural adhesive, specifically including the components shown in Table 2, wherein the amount of each component is "parts by weight";

[0057] Table 2

[0058]

[0059] The preparation method of the one-component epoxy structural adhesive provided in Examples 1 to 5 and Comparative Examples 1 to 5 includes: dispersing and mixing bisphenol A epoxy resin, polyurethane modified epoxy resin, liquid nitrile rubber modified epoxy resin, core-shell rubber toughening agent and active diluent under stirring conditions at a speed of 400 rpm for 0.5 h, adding microsilica powder and daytime black under stirring conditions of ≤-0.1 MPa and a speed of 400 rpm for 0.5 h, and then adding dicyandiamide, hydrazide complex, urea-based accelerator and imidazole accelerator under conditions of ≤-0.1 MPa and a speed of 110 rpm for 0.5 h to obtain the one-component epoxy structural adhesive.

[0060] Performance Testing:

[0061] (1) Shear strength: Tested according to the test method provided in GB / T 7124-2008, with the substrate being galvanized steel sheet;

[0062] (2) T-peel strength: Tested according to the test method provided in GB / T 2791-1995;

[0063] (3) Room temperature storage performance: Tested in accordance with the test method provided in HG / T 3075-2003.

[0064] The single-component epoxy structural adhesives provided in Examples 1 to 5 and Comparative Examples 1 to 5 were tested according to the above test method; wherein the curing conditions were 150° C. and 25 min, and the test data are summarized in Table 3;

[0065] Table 3

[0066] Shear strength / MPa T-peel strength / N / mm Normal temperature storage performance Example 1 30.6 15.2 More than 180 days Example 2 29.7 15.1 More than 180 days Example 3 29.9 14.5 More than 180 days Example 4 32.1 13.3 More than 180 days Example 5 28.7 14.8 More than 180 days Comparative Example 1 12.1 5.6 More than 180 days Comparative Example 2 3.2 1.2 30 days Comparative Example 3 11.4 6.1 More than 180 days Comparative Example 4 8.9 4.3 More than 180 days Comparative Example 5 2.5 1.3 45 days

[0067] According to the data in Table 1, it can be seen that the present invention uses two curing agents, dicyandiamide and hydrazide complex, and two accelerators, imidazole adduct and urea-based accelerator, to make the obtained one-component epoxy structural adhesive be cured at a lower temperature and have a longer storage time, and the cured product has better bonding strength and flexibility.

[0068] Specifically, the room temperature storage test of the one-component epoxy structural adhesive provided in Examples 1 to 5 shows that they can be stored for more than 180 days, and the shear strength of the cured product is as high as 28.7 to 32.1 MPa, and the T-peel strength is as high as 13.3 to 15.2 N / mm; while the one-component epoxy structural adhesive provided in Comparative Examples 1 to 5 has a significant decrease in storage stability, and the shear strength and T-peel strength of the cured product are also significantly decreased because the types of curing agents and / or curing accelerators used in the components are not within the scope specified by the present invention.

[0069] The applicant declares that the present invention illustrates a one-component epoxy structural adhesive and its preparation method and application through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention and addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A one-component epoxy structural adhesive, characterized in that: The one-component epoxy structural adhesive comprises the following components in parts by weight: 10-30 parts by weight of bisphenol A epoxy resin; 5-20 parts by weight of polyurethane modified epoxy resin; 10-30 parts by weight of core-shell rubber toughening agent; 1-10 parts by weight of active diluent; 1-5 parts by weight of dicyandiamide; 0.5-2 parts by weight of hydrazide complex; Imidazole adduct 0.3-1 parts by weight; Urea-based accelerator 0.3-1 parts by weight; The hydrazide complex is Ajinomoto's hydrazide complex AH-123; The imidazole adduct is PN-50 or PN-40 of Ajinomoto; The one-component epoxy structural adhesive also includes liquid nitrile rubber modified epoxy resin; The amount of liquid nitrile rubber modified epoxy resin in the one-component epoxy structural adhesive is not more than 20 parts by weight.

2. The one-component epoxy structural adhesive according to claim 1, characterized in that: The core material of the core-shell rubber toughener includes a copolymer of a diene and a monoene.

3. The one-component epoxy structural adhesive according to claim 1, characterized in that: The shell material of the core-shell rubber toughener includes epoxy-functionalized alkyl methacrylate homopolymer and / or copolymer.

4. The one-component epoxy structural adhesive according to claim 1, characterized in that: The reactive diluent includes a bifunctional reactive diluent.

5. The one-component epoxy structural adhesive according to claim 4, characterized in that: The bifunctional reactive diluent includes 1,4-butanediol diglycidyl ether and / or 1,6-hexanediol diglycidyl ether.

6. The one-component epoxy structural adhesive according to claim 1, characterized in that: The liquid nitrile rubber modified epoxy resin is a butadiene-acrylonitrile elastomer grafted modified bisphenol A epoxy resin.

7. The one-component epoxy structural adhesive according to claim 1, characterized in that: The one-component epoxy structural adhesive also includes fillers and / or thixotropic agents.

8. The one-component epoxy structural adhesive according to claim 7, characterized in that: The content of filler in the one-component epoxy structural adhesive is 15 to 20 parts by weight.

9. The one-component epoxy structural adhesive according to claim 7, characterized in that: The filler is an inorganic filler.

10. The one-component epoxy structural adhesive according to claim 7, characterized in that: The content of the thixotropic agent in the one-component epoxy structural adhesive is 3 to 6 parts by weight.

11. The one-component epoxy structural adhesive according to claim 7, characterized in that: The thixotropic agent includes white carbon black.

12. A method for preparing the one-component epoxy structural adhesive according to any one of claims 1 to 11, characterized in that: The preparation method comprises: mixing bisphenol A epoxy resin, polyurethane modified epoxy resin, core-shell rubber toughening agent, reactive diluent and liquid nitrile rubber modified epoxy resin, adding optional filler and optional thixotropic agent for mixing, and then adding dicyandiamide, hydrazide complex, imidazole adduct and urea-based accelerator for mixing to obtain the single-component epoxy structural adhesive.

13. The preparation method according to claim 12, characterized in that: The preparation method specifically comprises: at room temperature, mixing bisphenol A epoxy resin, polyurethane modified epoxy resin, core-shell rubber toughening agent, reactive diluent and liquid nitrile rubber modified epoxy resin under stirring conditions of 300-450 rpm for 0.2-1 h, adding optional filler and optional thixotropic agent under stirring conditions of -0.1 MPa and 300-450 rpm for 0.2-1 h, and then adding dicyandiamide, hydrazide complex, imidazole adduct and urea-based accelerator under stirring conditions of -0.1 MPa and 100-120 rpm for 0.2-1 h to obtain the single-component epoxy structural adhesive.

14. Use of the one-component epoxy structure according to any one of claims 1 to 11, characterized in that: The applications include bonding for automotive body structures.

15. The use according to claim 14, characterized in that: The automobile body comprises a steel automobile body.

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