Low-cost high-filling high-toughness two-component epoxy resin adhesive and preparation method thereof

Abstract

The invention provides a low-cost high-filling high-toughness bi-component epoxy resin adhesive. The low-cost high-filling high-toughness bi-component epoxy resin adhesive comprises a component A and a component B, wherein the component A comprises 20-35 parts of epoxy resin, 5-10 parts of a diluent, 20-40 parts of silica powder, 3-5 parts of titanium dioxide and 10-25 parts of nano calcium carbonate; the diluent is a reactive diluent with epoxy groups at two ends and an ether bond in the middle; a component B: 20-35 parts of a curing agent, 1-2 parts of an accelerant, 1-3 parts of a coupling agent, 30-40 parts of silica powder, 10-20 parts of nano calcium carbonate and 1-2 parts of fumed silica; the curing agent is an organic silicon modified amine curing agent containing Si-O bonds; the accelerant is a structure reaction type accelerant adopting C-C single bond connection; one end of the coupling agent contains an epoxy group, and the other end of the coupling agent contains an ethyoxyl group. The bi-component epoxy resin adhesive provided by the invention has the advantages of low cost, high toughness and impact resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of heat-curing epoxy resin compositions, and more particularly relates to a low-cost high-filling high-toughness two-component epoxy resin adhesive and a preparation method thereof. BACKGROUND

[0002] Epoxy resin has good bonding performance, chemical resistance, insulation, heat resistance and mechanical strength, low shrinkage during processing, and is easy to process and shape, and is widely used in adhesives, electronic packaging materials and coating materials, but epoxy resin is mainly synthesized by condensation of bisphenol A and epichlorohydrin, and the existence of aromatic ring in the molecular structure causes large internal stress, resulting in brittle and easy to crack of the cured product, which is difficult to meet the application requirements of specific occasions.

[0003] At present, the new energy automobile industry is developing rapidly in China, and due to the emergence of epoxy resin structural adhesive, the number of vehicle body welding points can be reduced, energy consumption and carbon emissions can be reduced, and higher reliability and fatigue resistance can be achieved, so the epoxy resin structural adhesive is widely used in major automobile manufacturers. However, the epoxy structural adhesive used by the automobile manufacturers is still mainly imported, which has high cost, and most of the epoxy structural adhesives are single-component, which need to be stored in a low-temperature environment, and the curing process needs to be heated to about 150 DEG C, which consumes a lot of energy and is contrary to the energy-saving and emission-reducing policy implemented by the country.

[0004] In view of the above, from the structure and application, it is of great significance to develop a low-cost, high-toughness, impact-resistant and domestically produced two-component epoxy resin adhesive. SUMMARY

[0005] In view of the shortcomings of the prior art, the application provides a low-cost high-filling high-toughness two-component epoxy resin adhesive to improve and optimize the high cost and poor toughness of the existing epoxy resin adhesive, which has the advantages of low cost, high toughness and impact resistance.

[0006] The technical scheme adopted to achieve the above-mentioned purposes of the application is as follows:

[0007] A low-cost high-filling high-toughness two-component epoxy resin adhesive, according to weight parts, comprising the following components Component A: epoxy resin 20-35 parts, diluent 5-10 parts, silicon powder 20-40 parts, titanium dioxide 3-5 parts, nano calcium carbonate 10-25 parts;

[0008] The diluent is an active diluent with epoxy groups at both ends and an ether bond in the middle;

[0009] Component B: curing agent 20-35 parts, accelerator 1-2 parts, coupling agent 1-3 parts, silicon powder 30-40 parts, nano calcium carbonate 10-20 parts, fumed silica 1-2 parts;

[0010] The curing agent is an amine curing agent modified by silicone containing Si-O bond;

[0011] The accelerator is a structural reactive accelerator connected by C-C single bond;

[0012] The coupling agent contains an epoxy group at one end and an ethoxy group at the other end;

[0013] The mass ratio of component A to component B is 0.8-1.2:1.

[0014] Further, the epoxy resin is E-51 bisphenol A epoxy resin, which has the following structure:

[0015] It has low price, easy availability of raw materials, high bonding strength and good mechanical properties.

[0016] Further, the diluent has the following structure: The active diluent is a diluent with double epoxy groups, which has small viscosity, good dilution effect, and does not damage the performance of the epoxy cured product, but enhances the crosslinking density. In addition, the unique ether bond group in the middle endows the overall structure with flexibility, which helps to improve the toughness of the cured adhesive and increase the impact strength.

[0017] Further, the silicon powder is amorphous silica powder, which is white powder with different particle sizes, generally spherical, and can play a "ball bearing" effect in the matrix of the composite material, significantly improving the flowability. In addition, spherical particles can reduce frictional resistance and increase partial slip, which helps to release intermolecular rigid stress and prevent brittle fracture between interfaces under impact force.

[0018] Further, the curing agent has the following structure:

[0019] The amine curing agent modified by silicone reacts with the epoxy group, which can introduce flexible Si-O bonds into the epoxy network structure. Si-O bonds can make the polymer chain segment rotate more easily, which can eliminate part of the internal stress, thereby improving the fracture toughness of the epoxy resin cured product. By combining silicone and epoxy resin cured product, the problem of insufficient toughness of the epoxy resin cured product can be solved.

[0020] Further, the accelerator is dimethyl dipropyl triamine, which has the following structure:

[0021] , the structure of the structure reaction type promoter connected by C-C single bond can improve the flexibility of the whole network structure more than DMP-30 (2, 4, 6-tri (dimethylaminomethyl) phenol) with benzene ring, and the benzene ring limits the rotation of the molecule, and the carbon-carbon single bond has small intermolecular resistance, and the intermolecular movement can improve the impact toughness.

[0022] Further, the coupling agent is KH-560, because the coupling agent KH-560 contains an epoxy group at one end to participate in the curing crosslinking reaction, and contains an ethoxy group at the other end, which can form a Si-O bond with the substrate surface hydroxyl group after hydrolysis, and the silicon oxygen bond has high bond energy and strong coupling with the substrate.

[0023] Further, the fumed silica is Wanjing A380, which is a hydrophilic fumed silica, and the specific surface area is 380 m 2 / g, mainly to adjust the rheological property of the rubber, and the viscosity of the rubber is too small to form effective contact; the viscosity is too large, which is not conducive to construction operation, and a small amount of fumed silica can enhance the rheological property of the rubber, and the surface of the fumed silica has a large number of hydroxyl groups, which can form hydrogen bonds between the epoxy resin curing product, and play a certain reinforcing role.

[0024] The application also provides a preparation method of the above-mentioned low-cost high-filled high-toughness two-component epoxy resin adhesive, comprising the following steps:

[0025] (1) according to the weight ratio, the epoxy resin, diluent, silicon powder, titanium dioxide and nano calcium carbonate in component A are added in sequence, and preliminary stirring is carried out to make the fillers uniformly dispersed;

[0026] (2) the above mixture A is placed in a high-speed dispersion machine and stirred, vacuumized, and stirred at 600 r / min for 3 min, and the vacuum degree is maintained at-101 KPa during the process, so as to fully stir uniformly and prevent the fillers from not being fully mixed and caked;

[0027] (3) according to the weight ratio, the curing agent, promoter, coupling agent, silicon powder, nano calcium carbonate and fumed silica in component B are added in sequence, and preliminary stirring is carried out to make the fillers uniformly;

[0028] (4) the above mixture B is placed in a high-speed dispersion machine and stirred, vacuumized, and stirred at 600 r / min for 3 min, and the vacuum degree is maintained at-101 KPa during the process, so as to fully stir uniformly and prevent the fillers from not being fully mixed and caked;

[0029] (5) finally, A component and B component are taken according to the mass ratio of A component and B component, and A component and B component are fully mixed at room temperature, so as to obtain a white paste-like epoxy resin curing product.

[0030] Compared with the prior art, the above technical scheme conceived by the present application has the following beneficial effects in general:

[0031] (1) The two-component epoxy resin adhesive of the present application has a simple formula, and the raw materials are easy to obtain, without the need for separate design and synthesis. It has the characteristics of wide repeated operation, long storage period, high toughness, and suitable curing temperature, solving the problem of high cost of two-component high-toughness epoxy resin adhesives on the market.

[0032] (2) In the present application, a certain amount of "flexible" chain segments are introduced into the epoxy resin network structure on the basis of rigid inorganic particle filler toughening, improving the activity of resin network molecules and thus improving the toughness. By optimizing the structure and adding fillers, and by pre-designing the molecular structure in the formula, the toughness of the epoxy resin cured product is improved. At the same time, the two-phase separation and delamination defects that often occur in the storage and aging process of conventional toughening methods (adding liquid rubber or thermoplastic resin for toughening) are avoided.

[0033] By optimizing the structure of the adhesive, adding a curing agent and an accelerator with a specific structure, and reacting to form an adhesive with high crosslinking density and flexible crosslinking network, the present application introduces flexible Si-O bonds into the epoxy network structure by selecting an epoxy resin curing agent with amine groups at both ends and Si-O in the middle of the molecular chain. Si-O bonds can make the high molecular chain segment rotate more easily, have a higher elongation, and can relieve intermolecular internal stress when impacted, thereby improving the impact toughness of the epoxy resin cured product. At the same time, the use of a structure of a C-C single bond connected reactive accelerator can improve the flexibility of the entire network structure. The intermolecular resistance of carbon-carbon single bond is small, and the intermolecular movement can further improve the impact toughness.

[0034] (3) The filler (i.e. silicon powder and nano calcium carbonate) in the present application can account for up to 60%, which can significantly reduce the cost. The filler in the resin matrix can induce silver streaks and prevent the expansion of silver streaks when silver streaks are generated. By selecting an appropriate particle size, stress concentration is easily formed when the particle size is too small, and the particle size is too large, which is equivalent to a two-phase system, which is not conducive to the improvement of toughness. When impacted, it can produce good plastic deformation. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The present application provides a schematic diagram of the two-component high-toughness impact-resistant epoxy resin adhesive after curing and interacting with the surface of the substrate. DETAILED DESCRIPTION

[0036] The present application relates to the field of epoxy resin adhesive, in particular to a single-component high-temperature-resistant epoxy resin adhesive and a preparation method thereof, which makes the adhesive and the base material have good adhesion and maintain high mechanical properties at high temperature, and is widely used in the adhesion and curing of the environment with high heat generated during the use of motors and electrical appliances.

[0037] Example 1

[0038] The two-component epoxy resin adhesive with low cost, high filling and high toughness according to weight parts comprises:

[0039] Component A:

[0040] Epoxy resin 30 parts: E-51 bisphenol A epoxy resin;

[0041] Diluent 10 parts: the structural formula is ;

[0042] Silica powder 35 parts: amorphous silica powder;

[0043] Titanium dioxide powder 3 parts: titanium dioxide powder;

[0044] Nano calcium carbonate 22 parts;

[0045] Component B:

[0046] Curing agent 30 parts: the structural formula is ;

[0047] Accelerator 2 parts: the structural formula is ;

[0048] Coupling agent 2 parts: KH-560;

[0049] Silica powder 40 parts: amorphous silica powder;

[0050] Nano calcium carbonate 15 parts;

[0051] Fumed silica 1 part: Yinkuang A380.

[0052] The preparation steps are as follows:

[0053] (1) The component A: epoxy resin 30 parts, diluent 10 parts, silica powder 35 parts, titanium dioxide powder 3 parts, and nano calcium carbonate 22 parts are sequentially added, and are preliminarily stirred to make the fillers uniform;

[0054] (2) The mixture is then placed in a high-speed dispersion machine and stirred, vacuumized, and stirred at a low speed of 600 r / min for 3 min, and the vacuum degree is maintained at-101 KPa during the process.

[0055] (3) The components B: curing agent 30 parts, promoter 2 parts, coupling agent 2 parts, silicon powder 40 parts, nano calcium carbonate 15 parts, fumed silica 1 part are added in turn, and the fillers are uniformly stirred;

[0056] (4) The mixture is placed in a high-speed dispersion machine and stirred, vacuumed, and stirred at a low speed of 600 r / min for 3 min, and the vacuum degree is maintained at-101 KPa during the process.

[0057] (5) Finally, the components A and B are taken in a mass ratio of 1:1 and mixed on a mixing plate until the color is uniform and there is no obvious color difference.

[0058] Example 2

[0059] In this example, the appropriate amount of resin is selected by adjusting the ratio of resin and filler. Since the unit price of resin is much higher than that of filler, under the condition of reasonable performance, the less the content of resin, the higher the content of filler, and the lower the cost. In Example 2 and Comparative Example 3, the reasonable amount of resin is mainly explored.

[0060] Component A: epoxy resin 35 parts; diluent 10 parts; silicon powder 30 parts; titanium white 3 parts; nano calcium carbonate 22 parts; Component B: curing agent 35 parts; promoter 2 parts; coupling agent 2 parts; silicon powder 35 parts; nano calcium carbonate 15 parts; fumed silica 1 part.

[0061] Comparative Example 1

[0062] The components in Comparative Example 1 are basically consistent with those in Example 1, and the difference is that the curing agent is not an amine curing agent modified by silicone, but a conventional aliphatic amine curing agent.

[0063] Comparative Example 2

[0064] The components in Comparative Example 1 are basically consistent with those in Example 1, and the difference is that the silicon powder selected is spherical silicon powder with a particle size of 800.

[0065] Comparative Example 3

[0066] In this comparative example, the reasonable amount of resin is mainly explored.

[0067] Component A: epoxy resin 25 parts; diluent 10 parts; silicon powder 40 parts; titanium white 3 parts; nano calcium carbonate 22 parts; Component B: curing agent 25 parts; promoter 2 parts; coupling agent 2 parts; silicon powder 45 parts; nano calcium carbonate 15 parts; fumed silica 1 part.

[0068] The products prepared in Examples 1-2 and Comparative Examples 1-3 and the commercially available ordinary epoxy resin adhesive product were subjected to the following performance tests: 1. Impact resistance test: ceramic plate bonded to stainless steel plate, directly dropped to the ground. 2. Shear strength: tensile testing machine.

[0069] The tests were carried out in accordance with the GB / T 21196.2 standard. After the tests, the test results are shown in the following table:

[0070]

[0071] As can be seen from the above performance test results, the low-cost high-filled high-toughness two-component epoxy resin adhesive prepared in Examples 1 and 2 has good impact strength and shear strength, and the principle diagram thereof is shown in Figure 1 , Figure 1 The upper and lower straight plates represent metal substrates / ceramic substrates, the transversely curved chain represents an amine curing agent with a long elongation, the blue particles represent a common epoxy resin E51, and the gray large particles represent fillers: amorphous silica powder and nano calcium carbonate. When subjected to strong impact, the above adhesive can absorb most of the energy through the long elongation and intermolecular chain movement, playing a role similar to a spring; in addition, the silica powder reduces the frictional resistance and is supplemented by partial slip, and the two work together to improve the toughness of the overall product.

[0072] Comparing Examples 1 and Comparative Example 1, it can be found that the final effects brought about by the two different types of curing agents are significantly different. The organic silicon-modified amine curing agent used in Example 1 has better molecular flexibility and elongation, and accordingly has better impact resistance. Comparing Examples 1 and Comparative Example 2, it can be found that the fillers affect the performance of the final product. Comparing Examples 1 and Comparative Example 3, it can be found that there is a balanced relationship between the proportion of resin and filler and the performance of the final product. Under the condition of meeting the impact resistance, the amount of resin and filler added is explored. It is finally found that the maximum amount of filler added cannot exceed about 60%, such as the amount of about 58% added in Example 1. Once the amount of filler added exceeds this range, the performance of the final product will decrease, for example, the total amount added in Comparative Example 3 is 64%. Comparing Examples 1, 2 and commercially available products, it can be found that the epoxy resin adhesive provided in the present application has more advantages than commercially available products.

[0073] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A low cost high filled high toughness two component epoxy resin adhesive, characterized in that, According to parts by weight, comprising the following components: Component A: epoxy resin 20-35 parts, diluent 5-10 parts, silicon powder 20-40 parts, titanium dioxide 3-5 parts, nano calcium carbonate 10-25 parts; The diluent is an active diluent with epoxy groups at both ends and an ether bond in the middle; Component B: curing agent 20-35 parts, accelerator 1-2 parts, coupling agent 1-3 parts, silicon powder 30-40 parts, nano calcium carbonate 10-20 parts, fumed silica 1-2 parts; The curing agent is an amine curing agent modified with Si-O bond containing silicone; The accelerator is a structural reactive accelerator connected by C-C single bond; The coupling agent contains an epoxy group at one end and an ethoxy group at the other end; The mass ratio of component A and component B is 0.8~1.2:

1.

2. The low cost high filled high toughness two component epoxy resin adhesive as claimed in claim 1, wherein, The epoxy resin is E-51 bisphenol A epoxy resin, whose structure is as follows: 。 3. The low cost high filled high toughness two component epoxy resin adhesive as claimed in claim 1, wherein, The structure of the diluent is as follows: 。 4. The low cost high filled high toughness two component epoxy resin adhesive as claimed in claim 1, wherein, The silicon powder is amorphous silica powder.

5. The low cost high filled high toughness two component epoxy resin adhesive as claimed in claim 1, wherein, The structure of the curing agent is as follows: 。 6. The low cost high filled high toughness two component epoxy resin adhesive as claimed in claim 1, wherein, The accelerator is dimethyl dipropyl triamine, whose structure is as follows: 。 7. The low cost high filled high toughness two component epoxy resin adhesive as claimed in claim 1, wherein, The coupling agent is KH-560.

8. The low cost high filled high toughness two component epoxy resin adhesive as claimed in claim 1, wherein, The fumed silica is Wacker A380.

9. A method for preparing the low-cost, high-filler, high-toughness two-component epoxy resin adhesive according to any one of claims 1-8, characterized in that, Including the following steps: (1) According to the weight ratio, the epoxy resin, diluent, silicon powder, titanium dioxide, nano calcium carbonate in component A are added in turn, and the fillers are uniformly dispersed by preliminary stirring; (2) Then the mixture A is placed in a high-speed dispersion machine and stirred, vacuumized, stirred at 600 r / min for 3 min, and the vacuum degree is maintained at-101 KPa during the process, and the fillers are fully stirred to prevent clumping due to insufficient mixing; (3) According to the weight ratio, the curing agent, accelerator, coupling agent, silicon powder, nano calcium carbonate, fumed silica in component B are added in turn, and the fillers are uniformly stirred by preliminary stirring; (4) Then the mixture B is placed in a high-speed dispersion machine and stirred, vacuumized, stirred at 600 r / min for 3 min, and the vacuum degree is maintained at-101 KPa during the process, and the fillers are fully stirred to prevent clumping due to insufficient mixing; (5) Finally, according to the mass ratio of component A and component B, component A and component B are taken, and component A and component B are fully mixed at room temperature to obtain white paste epoxy resin curing product.

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