A strong bonding epoxy adhesive with low linear expansion coefficient and preparation method thereof

Abstract

The present invention belongs to the field of adhesives, and specifically discloses a strong bonding low linear expansion coefficient epoxy adhesive and a preparation method thereof, wherein the epoxy adhesive comprises the following raw materials in parts by weight: 80-120 parts of epoxy resin, 5-20 parts of toughening agent, 5-10 parts of curing agent, 1-5 parts of curing accelerator, 1-3 parts of coupling agent, and 20-50 parts of filler. The hardness of the epoxy adhesive in the present invention is not less than 88HD, the tensile shear strength is not less than 20MPa, the peel strength is higher than 9N / cm, the bonding ability to metal is excellent, the average linear thermal expansion coefficient of the epoxy adhesive below the glass transition temperature is lower than 19μm / (m﹒℃), the average linear thermal expansion coefficient above the glass transition temperature is lower than 140μm / (m﹒℃), the glass transition temperature is 140-150℃, and the dimensional stability can be maintained to a great extent when the temperature changes.

Description

Technical Field

[0001] The invention belongs to the field of adhesives, and in particular relates to an epoxy adhesive with strong bonding and low linear expansion coefficient and a preparation method thereof. Background Art

[0002] One-component epoxy adhesive is a kind of engineering adhesive made of epoxy resin, latent curing agent and other additives. It has the advantages of good adhesion, simple bonding process, small curing shrinkage, good fatigue resistance, relatively low price, etc. It is more convenient to use than two-component epoxy adhesive and is widely used in machinery manufacturing, electronic equipment, automobile industry, aerospace and other industries. However, epoxy adhesive itself has the disadvantages of large internal stress, high brittleness and poor impact toughness, which limits its practical application.

[0003] About 50% of electronic device failures are caused by adhesive failure. Bond strength is an important indicator for evaluating adhesive performance. The bond strength of epoxy adhesives directly determines the overall strength of the bonded structure. If the bond strength is insufficient, the bonding interface may fail in the form of shearing, peeling or breaking, resulting in the destruction of the bonded structure. Good bond strength can provide better resistance to fatigue, aging and environmental corrosion, giving the bonded structure a longer service life. In addition, the linear thermal expansion coefficient of commonly used epoxy adhesives is large, and deformation will occur when the temperature changes, causing slight relative displacement between components. It will also bring internal stress, limiting its application in precision electronic devices. Summary of the invention

[0004] In order to overcome at least one technical problem existing in the above-mentioned prior art, one of the objectives of the present invention is to provide an epoxy adhesive.

[0005] The second object of the present invention is to provide a method for preparing an epoxy adhesive

[0006] A third object of the present invention is to provide a product.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention provides an epoxy adhesive, comprising the following raw materials in parts by weight: 80 to 120 parts of epoxy resin, 5 to 20 parts of toughening agent, 5 to 10 parts of curing agent, 1 to 5 parts of curing accelerator, 1 to 3 parts of coupling agent, and 20 to 50 parts of filler;

[0009] The toughening agent includes at least one of a mixture of nano core-shell rubber and epoxy resin, carboxyl-terminated nitrile rubber, polyurethane toughening agent, and polysulfide rubber. The main function of adding the toughening agent in the present invention is to improve the brittleness of the epoxy resin, improve its impact resistance, bending resistance, and peeling resistance, and also has a certain effect on improving the bonding of the epoxy adhesive to the substrate.

[0010] Preferably, the nano core-shell rubber has styrene-butadiene rubber (SBR) as the core and polymethyl methacrylate as the shell.

[0011] Preferably, in the mixture of the nano core-shell rubber and the epoxy resin, the nano core-shell rubber is uniformly dispersed in the epoxy resin in a single particle state, purchased from Dalian Liansheng New Materials Co., Ltd., wherein the epoxy resin can be bisphenol A epoxy resin. Preferably, the epoxy resin includes at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic modified epoxy resin, hydrogenated epoxy resin, dicyclopentadiene multifunctional epoxy resin, biphenyl epoxy resin, naphthalene epoxy resin, and aliphatic epoxy resin; further preferably, the epoxy resin includes at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, and phenolic modified epoxy resin. Dicyclopentadiene multifunctional epoxy resin is a new type of epoxy resin, a dicyclopentadiene multifunctional epoxy resin with multiple epoxy groups.

[0012] Preferably, the curing agent includes at least one of a ketimine curing agent, an aromatic diamine curing agent, a dicyandiamide curing agent, an imidazole curing agent, an organic acid anhydride curing agent, an organic hydrazide curing agent, a Lewis acid-amine complex curing agent, and an epoxy resin microcapsule curing agent; further preferably, the curing agent includes a dicyandiamide curing agent.

[0013] Preferably, the dicyandiamide curing agent is dicyandiamide.

[0014] Preferably, the ketimine curing agent is prepared by a chemical modification method by subjecting an aliphatic amine curing agent to a nucleophilic addition reaction with an organic ketone compound to generate a ketimine curing agent.

[0015] Preferably, the aliphatic amine curing agent includes at least one of ethylenediamine, hexamethylenediamine, diethylenetriamine and triethylenetetramine.

[0016] Preferably, the curing accelerator includes at least one of a modified amine curing accelerator, a substituted urea curing accelerator, and an imidazole curing accelerator; further preferably, the curing accelerator includes a substituted urea curing accelerator.

[0017] Preferably, the modified amine curing accelerator is an adduct of 2-ethyl-4-methylimidazole and isocyanate.

[0018] Preferably, the substituted urea curing accelerator includes at least one of 1,1'-(4-methyl-m-phenylene)bis(3,3-dimethylurea) and dimethylurea.

[0019] Preferably, the coupling agent includes at least one of vinyl trimethoxy silane, vinyl triethoxy silane, γ-aminopropyl triethoxy silane, γ-aminopropyl trimethoxy silane, and γ-glycidyl ether oxypropyl trimethoxy silane. In the present invention, the coupling agent can improve the bonding performance between the polymer material in the epoxy adhesive and the substrate surface.

[0020] Preferably, the filler includes at least one of nano calcium carbonate, silicon powder, aluminum hydroxide, aluminum oxide and carbon black.

[0021] Preferably, the filler comprises nano calcium carbonate and aluminum oxide in a mass ratio of 1: (0.1-2). The filler in the present invention can make the prepared epoxy adhesive have sufficient strength while reducing the linear expansion coefficient.

[0022] Preferably, the epoxy adhesive comprises the following raw materials in parts by weight: 90-110 parts of epoxy resin, 10-15 parts of toughening agent, 5-10 parts of curing agent, 1-5 parts of curing accelerator, 1-3 parts of coupling agent, and 30-50 parts of filler.

[0023] The second aspect of the present invention provides a method for preparing the epoxy adhesive described in the first aspect of the present invention, comprising the following steps: mixing various raw materials to obtain an epoxy adhesive.

[0024] Preferably, the preparation method comprises the following steps:

[0025] The epoxy resin and the toughening agent are stirred and mixed for 10 to 15 minutes, and then the curing agent and the curing accelerator are added and stirred and mixed for 40 to 60 minutes, and then the filler is added and stirred and mixed for 60 to 90 minutes, and then the coupling agent is added and stirred and mixed for 5 to 10 minutes to prepare the epoxy adhesive.

[0026] The third aspect of the present invention provides a product, comprising an adhesive layer; the adhesive layer is formed by curing the epoxy adhesive described in the first aspect of the present invention.

[0027] Preferably, the product is selected from electronic devices, household appliances, mechanical equipment, automobiles or aerospace equipment.

[0028] The beneficial effects of the present invention are as follows: the epoxy adhesive in the present invention is compounded with epoxy resin, curing agent and curing accelerator, and a toughening agent is added at the same time, so that the brittleness and bonding ability of the epoxy adhesive are significantly improved, so that the hardness of the prepared single-component epoxy adhesive is not less than 88HD, the tensile shear strength is not less than 20MPa, the peel strength is higher than 9N / cm, and the bonding ability to metal is excellent. The average linear thermal expansion coefficient of the epoxy adhesive below the glass transition temperature is lower than 19μm / (m﹒℃), and the average linear thermal expansion coefficient above the glass transition temperature is lower than 140μm / (m﹒℃), the glass transition temperature is 140-150℃, and the dimensional stability can be maintained to a great extent when the temperature changes, thereby expanding its application in fine electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the preparation process of the epoxy adhesive in the embodiment of the present invention. DETAILED DESCRIPTION

[0030] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. The reagents or instruments used that do not indicate the manufacturer are all conventional products that can be purchased commercially.

[0031] In some embodiments of the present invention, the present invention provides an epoxy adhesive, comprising the following raw materials in parts by weight: 80 to 120 parts of epoxy resin, 5 to 20 parts of toughening agent, 5 to 10 parts of curing agent, 1 to 5 parts of curing accelerator, 1 to 3 parts of coupling agent, and 20 to 50 parts of filler;

[0032] The toughening agent includes at least one of a mixture of nano core-shell rubber and epoxy resin, carboxyl-terminated nitrile rubber, a polyurethane toughening agent, and polysulfide rubber.

[0033] In some specific embodiments of the present invention, the nano core-shell rubber has styrene-butadiene rubber (SBR) as the core and polymethyl methacrylate as the shell.

[0034] In some specific embodiments of the present invention, in the mixture of nano core-shell rubber and epoxy resin, the nano core-shell rubber is uniformly dispersed in the epoxy resin in the form of single particles and is purchased from Dalian Liansheng New Materials Co., Ltd., wherein the epoxy resin can be bisphenol A epoxy resin.

[0035] In some specific embodiments of the present invention, the weight parts of the epoxy resin can be selected from 80 parts, 85 parts, 90 parts, 95 parts, 100 parts, 105 parts, 110 parts, 115 parts or 120 parts.

[0036] In some specific embodiments of the present invention, the weight parts of the toughening agent can be selected from 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts or 20 parts.

[0037] In some specific embodiments of the present invention, the weight parts of the curing agent can be selected from 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts.

[0038] In some specific embodiments of the present invention, the weight portion of the curing accelerator can be selected from 1 part, 2 parts, 3 parts, 4 parts or 5 parts.

[0039] In some specific embodiments of the present invention, the weight portion of the coupling agent can be selected from 1 part, 2 parts or 3 parts.

[0040] In some specific embodiments of the present invention, the weight proportion of the filler may be selected from 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts or 50 parts.

[0041] In some embodiments of the present invention, the epoxy resin includes at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic modified epoxy resin, hydrogenated epoxy resin, dicyclopentadiene multifunctional epoxy resin, biphenyl epoxy resin, naphthalene epoxy resin, and aliphatic epoxy resin; in some embodiments of the present invention, the epoxy resin includes at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, and phenolic modified epoxy resin. Dicyclopentadiene multifunctional epoxy resin is a new type of epoxy resin, a dicyclopentadiene multifunctional epoxy resin with multiple epoxy groups.

[0042] In some embodiments of the present invention, the curing agent includes at least one of a ketimine curing agent, an aromatic diamine curing agent, a dicyandiamide curing agent, an imidazole curing agent, an organic acid anhydride curing agent, an organic hydrazide curing agent, a Lewis acid-amine complex curing agent, and an epoxy resin microcapsule curing agent; in some embodiments of the present invention, the curing agent includes a dicyandiamide curing agent.

[0043] In some embodiments of the present invention, the dicyandiamide curing agent is dicyandiamide.

[0044] In some embodiments of the present invention, the ketimine curing agent is prepared by chemically modifying an aliphatic amine curing agent and an organic ketone compound to undergo a nucleophilic addition reaction to generate the ketimine curing agent.

[0045] In some embodiments of the present invention, the aliphatic amine curing agent includes at least one of ethylenediamine, hexamethylenediamine, diethylenetriamine, and triethylenetetramine.

[0046] In some embodiments of the present invention, the curing accelerator includes at least one of a modified amine curing accelerator, a substituted urea curing accelerator, and an imidazole curing accelerator; in some embodiments of the present invention, the curing accelerator includes a substituted urea curing accelerator.

[0047] In some embodiments of the present invention, the modified amine curing accelerator is an adduct of 2-ethyl-4-methylimidazole and isocyanate.

[0048] In some embodiments of the present invention, the substituted urea curing accelerator includes at least one of 1,1'-(4-methyl-m-phenylene)bis(3,3-dimethylurea) and dimethylurea.

[0049] In some embodiments of the present invention, the coupling agent includes at least one of vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and γ-glycidoxypropyltrimethoxysilane.

[0050] In some embodiments of the present invention, the filler includes at least one of nano calcium carbonate, silicon powder, aluminum hydroxide, aluminum oxide, and carbon black.

[0051] In some embodiments of the present invention, the filler includes nano calcium carbonate and aluminum oxide in a mass ratio of 1: (0.1-2).

[0052] In some embodiments of the present invention, the epoxy adhesive comprises the following raw materials in parts by weight: 90 to 110 parts of epoxy resin, 10 to 15 parts of toughening agent, 5 to 10 parts of curing agent, 1 to 5 parts of curing accelerator, 1 to 3 parts of coupling agent, and 30 to 50 parts of filler.

[0053] In some embodiments of the present invention, the present invention provides a method for preparing the above-mentioned epoxy adhesive, comprising the following steps: mixing various raw materials to obtain an epoxy adhesive.

[0054] like Figure 1 As shown, in some embodiments of the present invention, the preparation method of the epoxy adhesive provided by the present invention comprises the following steps:

[0055] The epoxy resin and toughening agent are stirred and mixed for 10 to 15 minutes, and then the curing agent and curing accelerator are added and stirred and mixed for 40 to 60 minutes, and then the filler is added and stirred and mixed for 60 to 90 minutes, and then the coupling agent is added and stirred and mixed for 5 to 10 minutes to prepare the epoxy adhesive.

[0056] In some embodiments of the present invention, the present invention provides a product including an adhesive layer; the adhesive layer is formed by curing the above-mentioned epoxy adhesive.

[0057] In some embodiments of the present invention, the product is selected from electronic devices, household appliances, mechanical equipment, automobiles or aerospace equipment.

[0058] The specific implementation of the present invention is further described in detail below in conjunction with specific embodiments:

[0059] The raw material information used in the examples and comparative examples of the present invention is as follows:

[0060] Bisphenol A type epoxy resin: epoxy resin NPEL128R, epoxy value is 196 (g / eq);

[0061] Core-shell epoxy toughening agent: a mixture of nano core-shell rubber and epoxy resin, wherein the nano core-shell rubber is made of styrene-butadiene rubber (SBR) as the core and polymethyl methacrylate as the shell. The epoxy resin is bisphenol A epoxy resin. The model of the core-shell epoxy toughening agent is toughened epoxy LSE-103-30, the epoxy equivalent is 266 (g / eq), and the content of the nano core-shell rubber is 30wt%, which is purchased from Dalian Liansheng New Materials Co., Ltd.

[0062] Dicyandiamide: particle size is 10 μm;

[0063] Substituted urea accelerator: dimethyl urea, particle size 10 μm;

[0064] Nano calcium carbonate: particle size is 18μm;

[0065] Spherical alumina: particle size is 5μm.

[0066] Example 1

[0067] This example provides an epoxy adhesive, which is composed of the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 12 parts of core-shell epoxy toughening agent, 8 parts of dicyandiamide, 3 parts of substituted urea accelerator, 3 parts of γ-glycidyloxypropyltrimethoxysilane, 20 parts of nano calcium carbonate, and 20 parts of spherical alumina.

[0068] The epoxy adhesive in this example is prepared by a preparation method comprising the following steps:

[0069] The bisphenol A epoxy resin and the core-shell epoxy toughening agent were stirred and mixed for 15 minutes, and then dicyandiamide and substituted urea accelerators were added and stirred for 60 minutes; nano calcium carbonate and spherical alumina were added and stirred for 90 minutes, and then γ-glycidyloxypropyltrimethoxysilane was added for 10 minutes, and the epoxy adhesive in this example was obtained.

[0070] Comparative Example 1

[0071] This example provides an epoxy adhesive, which is composed of the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 8 parts of dicyandiamide, 3 parts of substituted urea accelerator, 3 parts of γ-glycidyloxypropyltrimethoxysilane, 20 parts of nano calcium carbonate, and 20 parts of spherical alumina.

[0072] Comparative Example 2

[0073] This example provides an epoxy adhesive, which is composed of the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 12 parts of core-shell epoxy toughening agent, 8 parts of dicyandiamide, 3 parts of substituted urea accelerator, 20 parts of nano calcium carbonate, and 20 parts of spherical alumina.

[0074] Comparative Example 3

[0075] This example provides an epoxy adhesive, which is composed of the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 12 parts of core-shell epoxy toughening agent, 8 parts of dicyandiamide, 3 parts of substituted urea accelerator, 3 parts of γ-glycidyloxypropyltrimethoxysilane, and 20 parts of nano calcium carbonate.

[0076] The epoxy adhesives in Comparative Examples 1 to 3 can all be prepared by referring to the preparation method in Example 1.

[0077] Performance Test:

[0078] The epoxy adhesives in Example 1 and Comparative Examples 1 to 3 were cured to form adhesive layers, the curing temperature was uniformly 120°C, and the curing time was 60 min. Then, the properties of the adhesive layers were tested according to the following test standards, specifically: the hardness was measured using a Shore D durometer according to GB / T2411-2008 standard: the tensile shear strength (cold-rolled steel-cold-rolled steel) was tested according to GB / T 7124-2008 standard; the 180° peel strength (cold-rolled steel) was tested according to GB / T 2792-2014 standard; the average linear thermal expansion coefficient and the glass transition temperature Tg of the epoxy adhesive were measured using TMA (thermomechanical analyzer) according to ASTME831-19 standard. The specific test results are shown in Table 1 below.

[0079] Table 1 Test results of various properties of epoxy adhesive

[0080]

[0081] As can be seen from Table 1, the hardness of the epoxy adhesive in the present invention is not less than 88HD, the tensile shear strength is not less than 20MPa, the peel strength is higher than 9N / cm, and the bonding ability to metal is excellent. The average linear thermal expansion coefficient of the epoxy adhesive below the glass transition temperature is lower than 19μm / (m﹒℃), and the average linear thermal expansion coefficient above the glass transition temperature is lower than 140μm / (m﹒℃). The glass transition temperature is 140-150℃, which can maintain dimensional stability to a great extent when the temperature changes, and expand its application in fine electronic devices.

[0082] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. An epoxy adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: 80 to 120 parts of epoxy resin, 5 to 20 parts of toughening agent, 5 to 10 parts of curing agent, 1 to 5 parts of curing accelerator, 1 to 3 parts of coupling agent and 20 to 50 parts of filler; The toughening agent comprises at least one of a mixture of nano core-shell rubber and epoxy resin, carboxyl-terminated nitrile rubber, a polyurethane toughening agent, and polysulfide rubber.

2. The epoxy adhesive according to claim 1, characterized in that: The epoxy resin includes at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic modified epoxy resin, hydrogenated epoxy resin, dicyclopentadiene multifunctional epoxy resin, biphenyl epoxy resin, naphthalene epoxy resin and aliphatic epoxy resin.

3. The epoxy adhesive according to claim 1, characterized in that: The curing agent includes at least one of ketimine curing agent, aromatic diamine curing agent, dicyandiamide curing agent, imidazole curing agent, organic acid anhydride curing agent, organic hydrazide curing agent, Lewis acid-amine complex curing agent, and epoxy resin microcapsule curing agent.

4. The epoxy adhesive according to claim 1, characterized in that: The curing accelerator includes at least one of a modified amine curing accelerator, a substituted urea curing accelerator, and an imidazole curing accelerator.

5. The epoxy adhesive according to claim 1, characterized in that: The coupling agent includes at least one of vinyl trimethoxy silane, vinyl triethoxy silane, γ-aminopropyl triethoxy silane, γ-aminopropyl trimethoxy silane, and γ-glycidyloxypropyl trimethoxy silane.

6. The epoxy adhesive according to claim 1, characterized in that: The filler includes at least one of nano calcium carbonate, silicon powder, aluminum hydroxide, aluminum oxide and carbon black.

7. The epoxy adhesive according to claim 6, characterized in that: The filler comprises nano calcium carbonate and aluminum oxide in a mass ratio of 1: (0.1-2).

8. The method for preparing the epoxy adhesive according to any one of claims 1 to 7, characterized in that: The following steps are involved: The raw materials are mixed and prepared.

9. A product, characterized in that: It comprises a glue layer; the glue layer is formed by curing the epoxy adhesive according to any one of claims 1 to 7.

10. The product according to claim 9, characterized in that: The product is selected from electronic devices, household appliances, mechanical equipment, automobiles or aerospace equipment.

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