Single-component epoxy adhesive as well as preparation method and application thereof

Abstract

The invention provides a single-component epoxy adhesive as well as a preparation method and application thereof, and preparation raw materials of the single-component epoxy adhesive comprise the following components in parts by weight: 5-25 parts of epoxy resin; 10 to 30 parts of phenolic resin; 15 to 35 parts of an epoxy toughening agent; 2-8 parts of a dicyandiamide curing agent; 1-3 parts of a medium and low temperature type imidazole adduct curing accelerator; 0.6-3 parts of a liquid additive; and 20-32 parts of a powder auxiliary agent. According to the epoxy adhesive provided by the invention, the phenolic resin and the epoxy toughening agent are introduced, and the dicyandiamide curing agent and the medium and low temperature imidazole adduct curing accelerator system are matched, so that the epoxy adhesive has relatively high tensile-shear strength (greater than or equal to 20MPa) at high temperature (120 DEG C), can be applied to adhesion of automobile parts, and also has the advantages of high tensile-shear strength (greater than or equal to 20MPa), high tensile-shear strength (greater than or equal to 20MPa), high tensile-shear strength (greater than or equal to 20MPa) and high tensile-shear strength (greater than or equal to 20MPa). The epoxy adhesive has good mechanical properties, and the tensile strength, T-peel strength and tensile shear strength of the epoxy adhesive can meet the requirements of structural bonding at normal temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesives, and relates to a one-component epoxy adhesive, a preparation method and an application thereof, and in particular to a one-component epoxy adhesive with high tensile shear strength at high temperature, a preparation method and an application thereof. Background Art

[0002] Ordinary epoxy adhesives often have high tensile shear strength at low temperatures, but as the temperature rises, the epoxy cured product gradually softens, which greatly affects its tensile shear strength, making it unable to meet the normal bonding requirements of automotive parts in high temperature (120°C) workshops.

[0003] Adhesives with high tensile shear strength at high temperatures have been used in the aerospace field (can be applied to aircraft). For example, CN114605948A discloses a medium-low temperature curing high-temperature resistant high-strength epoxy adhesive, which provides an epoxy adhesive with a tensile shear strength of not less than 6.5MPa at 250°C, and the adhesive is mainly used in aircraft bonding, and is not suitable for bonding automotive parts. CN114752333A discloses a room temperature curing high-strength, high-toughness, high-temperature resistant epoxy structural adhesive and a preparation method, which provides a two-component epoxy adhesive, but the tensile shear strength of the epoxy adhesive at 100°C is only 6.46MPa and 6.82MPa.

[0004] Therefore, it is desirable to develop an epoxy adhesive having high tensile shear strength at a high temperature of 120° C. for application in bonding automotive parts. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a one-component epoxy adhesive and a preparation method and application thereof, and specifically to provide a one-component epoxy adhesive having high tensile shear strength (over 20MPa) at high temperature (120°C) and a preparation method and application thereof. The epoxy adhesive provided by the present invention is mainly aimed at automobile manufacturers and is mainly used in the bonding of automobile parts, playing a role in replacing traditional automobile processes such as welding and anchor bolts. At the same time, its construction temperature can be carried out at 120°C, which just fits the automobile production process, and after bonding, it can immediately enter the next production process to improve production efficiency.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a one-component epoxy adhesive, wherein the raw materials for preparing the one-component epoxy adhesive include the following components in parts by weight:

[0008]

[0009] The epoxy adhesive provided by the present invention, by introducing phenolic resin and epoxy toughening agent, and using dicyandiamide curing agent and medium-low temperature type imidazole adduct curing accelerator system in combination, enables the epoxy adhesive to have high tensile shear strength (≥20MPa) at high temperature (120°C), can be used for bonding of automobile parts, and the epoxy adhesive itself has good mechanical properties, and its tensile strength, T-peel strength and tensile shear strength at room temperature can meet the requirements of structural bonding.

[0010] In the present invention, the raw materials for preparing the one-component epoxy adhesive are calculated by weight, and the amount of epoxy resin used can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 25 parts, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0011] In the present invention, the raw materials for preparing the one-component epoxy adhesive are calculated by weight, and the amount of phenolic resin used can be 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0012] In the present invention, the raw materials for preparing the one-component epoxy adhesive are calculated by weight, and the amount of the epoxy toughening agent used can be 15 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 34 parts, 35 parts, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0013] In the present invention, the raw materials for preparing the one-component epoxy adhesive are calculated by weight, and the amount of dicyandiamide curing agent used can be 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, etc., as well as specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0014] In the present invention, the raw materials for preparing the one-component epoxy adhesive are measured in parts by weight, and the amount of the medium and low temperature imidazole adduct curing accelerator can be 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2 parts, 2.1 parts, 2.2 parts, 2.3 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.7 parts, 2.8 parts, 2.9 parts, 3 parts, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0015] In the present invention, the raw materials for preparing the one-component epoxy adhesive are calculated by weight, and the amount of the liquid additive can be 0.6 parts, 0.8 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts, 3 parts, etc., as well as specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0016] In the present invention, the raw materials for preparing the one-component epoxy adhesive are calculated by weight, and the amount of the powder additive can be 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0017] Preferably, the epoxy resin comprises bisphenol A epoxy resin and / or bisphenol F epoxy resin, preferably bisphenol A epoxy resin.

[0018] Preferably, the epoxy resin includes any one of E51, E54, and E44 or a combination of at least two thereof, preferably epoxy resin E51.

[0019] Preferably, the phenolic resin comprises a thermosetting phenolic resin.

[0020] Preferably, the epoxy toughening agent comprises a core-shell rubber epoxy toughening agent.

[0021] Preferably, the curing temperature of the medium- and low-temperature imidazole adduct curing accelerator is 80-120°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0022] Preferably, the liquid auxiliary agent comprises a diluent and / or an adhesion promoter.

[0023] Preferably, the liquid additive includes 0.5 to 2 parts of a diluent (for example, 0.5 parts, 1 parts, 1.5 parts, 2 parts, etc., as well as specific values ​​between the above-mentioned points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific values ​​included in the range), and 0.1 to 1 part of an adhesion promoter (for example, 0.1 parts, 0.3 parts, 0.5 parts, 0.6 parts, 0.8 parts, 1 parts, etc., as well as specific values ​​between the above-mentioned points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific values ​​included in the range).

[0024] Preferably, the diluent comprises a difunctional epoxy reactive diluent and / or a multifunctional epoxy reactive diluent, preferably 1,6-hexanediol diglycidyl ether.

[0025] Preferably, the powder additive comprises a filler and / or a rheological additive.

[0026] Preferably, the powder additive includes 20 to 30 parts of filler (for example, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range), and 0.5 to 2 parts of rheological additive (for example, 0.5 parts, 1 parts, 1.5 parts, 2 parts, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range).

[0027] Preferably, the filler comprises heavy calcium and / or calcium carbonate. Preferably, the filler is dried before use.

[0028] Preferably, the rheology additive comprises fumed silica.

[0029] Preferably, the raw materials for preparing the one-component epoxy adhesive also include a desiccant.

[0030] Preferably, the amount of the desiccant is 1 to 3 parts, for example, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0031] Preferably, the desiccant comprises a molecular sieve desiccant.

[0032] As a preferred technical solution of the present invention, the raw materials for preparing the one-component epoxy adhesive include the following components in parts by weight:

[0033]

[0034] In a second aspect, the present invention provides a method for preparing the one-component epoxy adhesive as described in the first aspect, the preparation method comprising the following steps:

[0035] The epoxy resin, phenolic resin, epoxy toughening agent and liquid additive are mixed and dispersed for the first time, and then the powder additive is added and dispersed for the second time. Thereafter, a dicyandiamide curing agent, a medium-low temperature type imidazole adduct curing accelerator and an optional desiccant are added and dispersed for the third time to obtain the one-component epoxy adhesive.

[0036] Preferably, the first dispersion, the second dispersion and the third dispersion are all performed under vacuum conditions.

[0037] Preferably, the dispersion temperatures of the first dispersion, the second dispersion and the third dispersion are each independently 50-60°C, for example 50°C, 55°C, 60°C, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0038] Preferably, the time for the first dispersion is 30 to 40 minutes, for example 30 minutes, 35 minutes, 40 minutes, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0039] Preferably, the time for the second dispersion is 40 to 60 min, for example 40 min, 45 min, 50 min, 55 min, 60 min, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0040] Preferably, the time for the third dispersion is 40 to 60 min, for example 40 min, 45 min, 50 min, 55 min, 60 min, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0041] In a third aspect, the present invention provides a use of the one-component epoxy adhesive as described in the first aspect in bonding automobile parts.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] The epoxy adhesive provided by the present invention, by introducing phenolic resin and epoxy toughening agent, and using dicyandiamide curing agent and medium-low temperature type imidazole adduct curing accelerator system in combination, enables the epoxy adhesive to have high tensile shear strength (≥20MPa) at high temperature (120°C), can be used for bonding of automobile parts, and the epoxy adhesive itself has good mechanical properties, and its tensile strength, T-peel strength and tensile shear strength at room temperature can meet the requirements of structural bonding. DETAILED DESCRIPTION

[0044] 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.

[0045] Unless otherwise specified, the raw material information used in the following examples and comparative examples of the present invention is as follows:

[0046]

[0047] Example 1

[0048] In this embodiment, a one-component epoxy adhesive is provided. The specific selection and dosage (parts by weight) of the raw materials for preparing the one-component epoxy adhesive are shown in Table 1.

[0049] The preparation method comprises the following steps:

[0050] First, calcium carbonate and fumed silica were dried at 102°C for 48 hours. According to the formula in Table 1, epoxy resin, phenolic resin, diluent, epoxy toughening agent, and adhesion promoter were mixed, and vacuum dispersed in a stirred tank for 35 minutes in advance. After mixing evenly, calcium carbonate and fumed silica that were cooled to room temperature after drying were added, and vacuum dispersed for 50 minutes. Then, dicyandiamide curing agent, medium and low temperature imidazole adduct curing accelerator, and molecular sieve desiccant were added. After vacuum dispersion for 50 minutes, the material was discharged and packaged to obtain the one-component epoxy adhesive, wherein the temperature was controlled at 55°C during the entire vacuum dispersion process.

[0051] Examples 2-6, Comparative Examples 1-5

[0052] The difference from Example 1 is that the amounts (parts by weight) of the raw materials used in the preparation are different, as shown in Tables 1 and 2.

[0053] Table 1

[0054]

[0055] Table 2

[0056]

[0057] The performance test of the one-component epoxy adhesive provided in the embodiment and the comparative example is carried out as follows:

[0058] (1) High temperature (120°C) tensile shear strength and room temperature tensile shear strength: in accordance with GB / T 7124;

[0059] (2) T-peel strength: according to GB / T 2791;

[0060] (3) Tensile strength: Conduct the tensile test in accordance with the requirements of GB / T 2567.

[0061] The performance test results are shown in Table 3.

[0062] Table 3

[0063]

[0064] It can be seen from Table 3 that the one-component epoxy adhesive provided by the embodiment of the present invention has a high shear strength (20-23 MPa) at high temperature (120°C), and can be used for bonding automotive parts. In addition, the epoxy adhesive itself has good mechanical properties. At room temperature, its tensile strength (32-36 MPa), T-peel strength (6.5-8.5 N / mm) and shear strength (28-34 MPa) can meet the requirements of structural bonding.

[0065] Compared with Example 1, the shear strength of the one-component epoxy adhesive provided in Comparative Example 1 at high temperature is greatly reduced, and the tensile strength, T-peel strength and shear strength of the epoxy adhesive at room temperature are also significantly reduced; the shear strength of the one-component epoxy adhesives provided in Comparative Examples 2-3 at high temperature is reduced, and the tensile strength, T-peel strength and shear strength are also slightly reduced; the shear strength of the one-component epoxy adhesive provided in Comparative Example 4 at high temperature is significantly reduced, and the tensile strength, T-peel strength and shear strength are also significantly reduced; the shear strength of the one-component epoxy adhesive provided in Comparative Example 5 at high temperature is slightly reduced, and the tensile strength, T-peel strength and shear strength at room temperature are also slightly reduced, but the presence of 2-ethyl-4-methylimidazole greatly shortens the storage time of the formulation.

[0066] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the one-component epoxy adhesive and its preparation method and application, 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, 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 adhesive, characterized in that: The raw materials for preparing the one-component epoxy adhesive include the following components in parts by weight:

2. The one-component epoxy adhesive according to claim 1, characterized in that: The epoxy resin includes bisphenol A epoxy resin and / or bisphenol F epoxy resin; Preferably, the epoxy resin includes any one of E51, E54, and E44, or a combination of at least two thereof; Preferably, the phenolic resin comprises a thermosetting phenolic resin.

3. The one-component epoxy adhesive according to claim 1 or 2, characterized in that: The epoxy toughening agent includes a core-shell rubber epoxy toughening agent; Preferably, the curing temperature of the medium- and low-temperature imidazole adduct curing accelerator is 80-120°C.

4. The one-component epoxy adhesive according to any one of claims 1 to 3, characterized in that: The liquid additive includes a diluent and / or an adhesion promoter; Preferably, the liquid additive includes 0.5 to 2 parts of a diluent and 0.1 to 1 part of an adhesion promoter; Preferably, the diluent comprises a difunctional epoxy reactive diluent and / or a multifunctional epoxy reactive diluent, preferably 1,6-hexanediol diglycidyl ether.

5. The one-component epoxy adhesive according to any one of claims 1 to 4, characterized in that: The powder additives include fillers and / or rheological additives; Preferably, the powder additive includes 20 to 30 parts of filler and 0.5 to 2 parts of rheological additive; Preferably, the filler comprises heavy calcium and / or calcium carbonate; Preferably, the rheology additive comprises fumed silica.

6. The one-component epoxy adhesive according to any one of claims 1 to 5, characterized in that: The raw materials for preparing the one-component epoxy adhesive also include a desiccant; Preferably, the amount of the desiccant is 1 to 3 parts; Preferably, the desiccant comprises a molecular sieve desiccant.

7. The one-component epoxy adhesive according to any one of claims 1 to 6, characterized in that: The raw materials for preparing the one-component epoxy adhesive include the following components in parts by weight:

8. A method for preparing a one-component epoxy adhesive as claimed in any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: The epoxy resin, phenolic resin, epoxy toughening agent and liquid additive are mixed and dispersed for the first time, and then the powder additive is added and dispersed for the second time. Thereafter, a dicyandiamide curing agent, a medium-low temperature type imidazole adduct curing accelerator and an optional desiccant are added and dispersed for the third time to obtain the one-component epoxy adhesive.

9. The preparation method according to claim 8, characterized in that: The first dispersion, the second dispersion and the third dispersion are all carried out under vacuum conditions; Preferably, the dispersion temperatures of the first dispersion, the second dispersion and the third dispersion are each independently 50 to 60° C.; Preferably, the first dispersion time is 30 to 40 minutes; Preferably, the second dispersion time is 40 to 60 minutes; Preferably, the third dispersion time is 40 to 60 minutes.

10. Use of the one-component epoxy adhesive according to any one of claims 1 to 7 in bonding automobile parts.

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