Solvent-free epoxy two-component laminated adhesive as well as preparation method and application thereof

Abstract

The invention discloses a solvent-free epoxy two-component laminated adhesive as well as a preparation method and application thereof, belongs to the technical field of adhesives, and solves the problems that an existing two-component epoxy resin adhesive is relatively high in volatile organic compound content, relatively strong in pungent smell during use, irritant to eyes and breath, poor in adhesion and the like. The VOCs can cause hypodynamia symptoms such as skin allergy, headache and sore throat, and part of VOCs also have carcinogenicity; the invention aims to solve the technical problem that VOCs (Volatile Organic Compounds) can escape in a curing process in which the VOCs participate in a reaction, so that the performance of an adhesive is reduced, and the adhesive is prepared by compounding the following substances: 20-50 parts of epoxy resin, 20-50 parts of a toughening agent, 1-5 parts of a coupling agent and 10-30 parts of a diluent, the curing agent comprises the following components in parts by weight: 5-10 parts of an aliphatic amine curing agent, 10-20 parts of a polyether amine curing agent, 0.1-2 parts of a tertiary amine curing accelerator, 20-50 parts of a phenol curing accelerator and 10-30 parts of reinforcing filler. The epoxy adhesive has excellent comprehensive performance, has the advantages of good adhesive force, high peel strength, easy blade coating and the like, and overcomes the defects of heavy smell, high VOC emission (gt; 150g / L), and the brittleness of the epoxy glue is high.

Description

Technical Field

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

[0002] Two-component epoxy resin adhesive is a high-performance adhesive material, which is widely used in various fields, including the bonding and fixing of electronic components, crafts, gifts, and the encapsulation and bonding between metals, ceramics, wood, glass and hard plastics. When using, the A agent (main agent) and the B agent (hardener) are mixed in a certain proportion for curing. The curing time ranges from a few minutes to a few days. Since the two-component epoxy resin adhesive contains volatile organic compounds (VOCs) such as acetone, toluene, and styrene, it has certain toxicity and should be used in a well-ventilated environment.

[0003] However, the existing two-component epoxy resin adhesives have a high content of volatile organic compounds and a strong pungent odor when used, which can irritate the eyes and respiratory system, cause skin allergies, headaches, sore throats and other fatigue symptoms. Some VOCs are also carcinogenic; and VOCs will escape during the curing process of the reaction, reducing the performance of the adhesive. Summary of the invention

[0004] The technical solution adopted by the present invention is as follows:

[0005] A solvent-free epoxy two-component laminating adhesive, comprising component A and component B.

[0006] Component A includes the following raw materials by weight: 20 to 50 parts of epoxy resin, 20 to 50 parts of toughening agent, 1 to 5 parts of coupling agent and 10 to 30 parts of diluent;

[0007] Component B includes the following raw materials in parts by weight: 5 to 10 parts of aliphatic amine curing agent, 10 to 20 parts of polyether amine curing agent, 0.1 to 2 parts of tertiary amine curing accelerator, 20 to 50 parts of phenolic curing accelerator and 10 to 30 parts of reinforcing filler.

[0008] Preferably, the epoxy resin is selected from at least one of epoxy resin E-44, epoxy resin E-51 and EPON 862 epoxy resin.

[0009] Preferably, the toughening agent is selected from pure acrylate oligomers or epoxy acrylate oligomers.

[0010] When the above technical scheme is adopted, the epoxy resin has low elongation, poor toughness and high brittleness when it is not modified. When subjected to internal and external stresses, the cured product will crack and have poor mechanical shock and thermal shock resistance. Therefore, a toughening agent needs to be added; the active toughening agent contains active groups, which can participate in the curing reaction of the epoxy resin and can also be miscible with the epoxy resin to play a toughening role. It can improve the toughness of the system, reduce the internal stress generated during the curing process, and significantly improve the tensile shear strength of the adhesive. There are many active groups in its molecular structure that can participate in the curing reaction of the epoxy resin under appropriate conditions. Because of the introduction of chain segments with better flexibility, the elongation and impact strength of the epoxy cured product are improved, such as: thiol-containing, terminal bromine-containing, and terminal carboxyl-containing rubbers; the inactive toughening agent does not contain active groups, is only miscible with the epoxy resin without chemical reaction, and most of them are liquids with low viscosity and have a diluting effect , which is conducive to the diffusion, adsorption and wetting of the adhesive on the bonding surface, and can increase fluidity, making the cured product tougher, but the inactive toughening agent cannot participate in the curing reaction of the epoxy resin, which will greatly reduce the modulus and strength of the epoxy cured product; some active toughening agents such as nitrile rubber have greatly improved impact resistance and adhesive body fracture as the amount added increases, but because the interface connection between the rubber particles and the epoxy matrix is ​​too strong and the compatibility is poor, the deformation of the rubber ions when subjected to force is limited, and it is not easy to separate into phases during the reaction process, the cohesive strength is reduced, the specimen shows cohesive failure, and the tensile shear strength is reduced; therefore, this application selects active toughening agent pure acrylate oligomer or epoxy acrylate oligomer as a toughening agent, which has excellent compatibility with epoxy resin, and can participate in the epoxy curing reaction to form a macromolecular polymer, greatly reducing the internal stress of the glue system and increasing the viscoelasticity of the glue system.

[0011] Preferably, the coupling agent is one of KH-550 and KH560.

[0012] By adopting the above technical scheme, the coupling agent has compounds with different groups at both ends of the molecule, one end of which can react with the surface of the adherend, and the other end can react with the adhesive molecule. Therefore, the adherend and the adhesive can be tightly connected together in the form of chemical bonds, changing the interface properties, increasing the bonding force, and improving the strength, heat resistance and moisture-heat aging resistance of the adhesive joint.

[0013] Preferably, the diluent is a high-boiling point unsaturated acrylic ester active diluent.

[0014] In the above technical scheme, the addition of diluent is to reduce the viscosity of the epoxy resin formula system and improve the process performance. Commonly used diluents are acetone, toluene and styrene, etc., but these are inactive diluents and do not participate in the curing reaction. Therefore, they only play the role of diluting the viscosity in the whole system. In addition, the boiling points of the above-mentioned inactive diluents are low and are not environmentally friendly. They are easy to volatilize to form VOCs, which are irritating and toxic. Therefore, this application adopts high-boiling point unsaturated acrylate active diluents, which can produce a curing reaction with epoxy resin, will not affect the performance of the cured product and are not easy to volatilize. The diluent is used as a part of the curing reaction, which eliminates the selection of volatile solvents that do not participate in the reaction, reduces the cost of use, and avoids the generation of obvious irritating odors and VOCs emissions.

[0015] Preferably, the aliphatic amine curing agent is selected from 1,3-diaminomethylcyclohexane or N-aminoethylpiperazine.

[0016] Using the above technical solution, usually in amine curing agents, because hydrogen bonding can accelerate the reaction between amino groups and epoxy groups, compounds with functional groups that are conducive to the generation of hydrogen bonds will promote the reaction, such as compounds with substituents such as "-OH", "-COOH", "-SO3H", "-CONH2", "-CONHR" and the like; the promotion effects of the commonly used fatty amine curing agents are arranged from high to low as phenol>triphenylphosphine>carboxylic acid>alcohol>tertiary amine>polythiol; these compounds can accelerate the curing of epoxy resins, reduce the curing temperature, and shorten the curing time.

[0017] Preferably, the polyetheramine curing agent is selected from one or more of polyetheramine D230, D400 and D2000.

[0018] Preferably, the tertiary amine curing accelerator in the present invention is 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30).

[0019] By adopting the above technical solution, the promoting effect of tertiary amine on the curing reaction is related to the electron density on the nitrogen atom in its structure and the length of the molecular chain. The greater the electron density on the nitrogen atom and the shorter the molecular chain, the greater the promoting effect.

[0020] Preferably, the phenolic curing accelerator in the present invention is one or more of phenol, resorcinol, o-cresol, nonylphenol, and bisphenol A.

[0021] Preferably, the reinforcing filler includes one or more of asbestos fiber, glass fiber, mica powder, aluminum powder, cement, porcelain powder, talcum powder, nano calcium carbonate powder, copper powder, iron powder, magnesium oxide, aluminum oxide, aluminum silicate, and titanium dioxide.

[0022] By adopting the above technical scheme, since the filler can reduce the shrinkage stress and thermal stress and thicken the glue or increase the viscosity, the shrinkage rate and thermal expansion coefficient of the glue layer during curing can be reduced, the thermal conductivity can be increased, and the cohesive strength of the shear strength of the adhesive bonding can be improved, thereby significantly improving the adhesion, mechanical strength (hardness, compressive strength), corrosion resistance and heat resistance, significantly reducing the shrinkage, greatly reducing the cost, making the viscosity of the adhesive moderate, and at the same time adjusting the lubrication performance and improving the operating process environment; the filler used in the present invention does not chemically react with the curing agent and other auxiliary agents of the epoxy resin, and is not easy to be stratified with the epoxy resin during the configuration process.

[0023] A method for preparing a solvent-free epoxy two-component coating adhesive, which is used to prepare the above-mentioned solvent-free epoxy two-component coating adhesive, comprises the following steps:

[0024] Step 1: Evenly mix epoxy resin, toughening agent, coupling agent and diluent to obtain component A; evenly mix aliphatic amine curing agent, polyether amine curing agent, tertiary amine curing accelerator and phenolic curing accelerator, and then add reinforcing filler and mix evenly to obtain component B;

[0025] Step 2: Mix the component A and the component B described in step 1 in a mass ratio of A:B=1:0.8-1 to obtain a solvent-free epoxy two-component coating adhesive.

[0026] An application of a solvent-free epoxy two-component laminating adhesive, wherein the solvent-free epoxy two-component laminating adhesive is applied to bonding between a polymer film and a hard substrate.

[0027] Preferably, the polymer film is a flexible sheet structure with a thickness of 0.05 to 5 mm, and the hard substrate includes metal, glass, ceramic, bamboo, carbon fiber, glass fiber, hard foam, ABS, PVC, nylon, and plastic.

[0028] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0029] 1. When epoxy resin is not modified, it has low elongation, poor toughness and high brittleness. When subjected to internal and external stresses, the cured product will crack and have poor mechanical shock and thermal shock resistance. Therefore, a toughening agent needs to be added. The active toughening agent contains active groups, which can participate in the curing reaction of epoxy resin and can also be miscible with epoxy resin to play a toughening role. It can improve the toughness of the system, reduce the internal stress generated during the curing process, and significantly improve the tensile shear strength of the adhesive. There are many active groups in its molecular structure that can participate in the curing reaction of epoxy resin under appropriate conditions. Because of the introduction of flexible chain segments, the elongation and impact strength of epoxy cured products are improved, such as: thiol-containing, terminal bromine-containing, and terminal carboxyl-containing rubbers. Inactive toughening agents do not contain active groups and are only miscible with epoxy resins without chemical reactions. Most of them are liquids with low viscosity and have a diluting effect. It is conducive to the diffusion, adsorption and infiltration of the adhesive liquid on the bonding surface, and can increase fluidity, so that the cured product has good toughness, but the inactive toughening agent cannot participate in the curing reaction of the epoxy resin, which will greatly reduce the modulus and strength of the epoxy cured product; as the amount of some active toughening agents such as nitrile rubber increases, although the impact resistance and the fracture of the adhesive body are greatly improved, the interface connection between the rubber particles and the epoxy matrix is ​​too strong, the compatibility is poor, which limits the deformation of the rubber ions when they are stressed, and it is not easy to separate phases during the reaction process, the cohesive strength is reduced, the test piece is cohesively damaged, and the tensile shear strength is reduced; therefore, this application selects pure acrylate oligomers or epoxy acrylate oligomers as toughening agents, which have excellent compatibility with epoxy resins, and can participate in the epoxy curing reaction to form macromolecular polymers, greatly reducing the internal stress of the glue system and increasing the viscoelasticity of the glue system;

[0030] 2. The addition of diluent is to reduce the viscosity of the epoxy resin formula system and improve the process performance. Commonly used diluents are acetone, toluene and styrene, etc., but these are inactive diluents and do not participate in the curing reaction. Therefore, they only play the role of diluting the viscosity in the whole system. In addition, the boiling points of the above-mentioned inactive diluents are low and are not environmentally friendly. They are easy to volatilize to form VOCs, which are irritating and toxic. Therefore, this application adopts high-boiling point unsaturated acrylate active diluents, which can produce a curing reaction with epoxy resin, will not affect the performance of the cured product and are not easy to volatilize. The diluent is used as a part of the curing reaction, which eliminates the selection of volatile solvents that do not participate in the reaction, reduces the cost of use, and avoids the generation of obvious irritating odors and VOCs emissions.

[0031] 3. The present invention introduces double bonds with higher activity into the reaction system by adding active toughening agents and active diluents, so that the reaction product has both rigid segments with the properties of bisphenol A and high molecular weight flexible segments with glue properties; the two resins selected by the toughening agent have good adhesion to the substrate alone, and because the rigidity of the glue system is too strong, the adhesion is low and the bonding is poor, and the rigidity is too weak, poor drying and low peel strength are prone to occur. After introducing it into our glue system, the toughening agent selected by the present invention can be added to the system while maintaining its adhesion, and can also well balance the rigidity and flexibility and strength of the system. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0033] Examples 1 to 3 and Comparative Examples 1 to 2

[0034] The two-component adhesives described in Examples 1 to 3 and Comparative Examples 1 to 2 are prepared by compounding the substances and mass fractions described in Table 1 below in terms of percentage content using the following steps:

[0035] Step 1: Mix the materials used in component A evenly to obtain component A; mix the other materials of component B except the reinforcing filler evenly, and then add the reinforcing filler and mix evenly to obtain component B;

[0036] Step 2: Mix the component A and the component B described in step 1 in a mass ratio of A:B=1:0.8-1 to obtain a two-component adhesive.

[0037] Table 1: Record of additives and addition amounts of the two-component adhesives described in Examples 1 to 5 and Comparative Examples 1 to 4 in parts by weight

[0038]

[0039] The present invention performs a peel strength test according to the ASTM D903 standard to test the peel strength of the composite product at 180° (dried at room temperature for 24 hours). In order to avoid the situation where the film is easily broken and the peel strength cannot be effectively tested, the present invention selects a PET film with high stiffness, low surface tension, and difficult adhesion as the test object.

[0040] Table 2: Peel strength test data of two-component adhesives prepared in Examples 1 to 5 and Comparative Examples 1 to 4 based on different substrates

[0041]

[0042]

[0043] The VOC emission in Examples 1 to 3 and Comparative Examples 1 to 2 was tested in accordance with the Chinese environmental standard "HJ 759-2015 Determination of Volatile Organic Compounds in Ambient Air by Tank Sampling Gas Chromatography-Mass Spectrometry".

[0044] Table 3: VOC emission of two-component adhesives prepared using Examples 1 to 3 and Comparative Examples 1 to 2

[0045]

[0046] In summary, the epoxy two-component adhesive prepared by the present invention has excellent comprehensive performance through the coordination of various components, and has the advantages of good adhesion, high peel strength, easy scraping, etc., while overcoming the shortcomings of ordinary epoxy adhesives such as heavy odor, high VOC emissions (>150g / L), high brittleness of epoxy adhesives, and unsuitability for bonding elastic or soft material products, and can be cured at room temperature to achieve continuous production;

[0047] 1,6-Hexanediol diacrylate (HDDA) as a reactive diluent not only participates in the curing reaction, but also has a dilution effect, with little effect on the performance of the cured product. The addition of HDDA can reduce the viscosity of the adhesive, increase its fluidity and permeability, thereby improving the wettability of the adhesive to the substrate and further improving the adhesion; due to the synergistic effect of the reactive toughening agent and the reactive diluent, the flexibility and adhesion of the adhesive are improved, which directly affects the improvement of the peel strength. The peel strength is the ability of the adhesive to resist separation when subjected to the peel force. The improvement of flexibility and adhesion makes the adhesive less likely to break when subjected to the peel force, thereby improving the peel strength.

[0048] It should be noted that:

[0049] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A solvent-free epoxy two-component coating adhesive, characterized in that: It includes component A and component B. Component A includes the following raw materials by weight: 20 to 50 parts of epoxy resin, 20 to 50 parts of toughening agent, 1 to 5 parts of coupling agent and 10 to 30 parts of diluent; Component B includes the following raw materials in parts by weight: 5 to 10 parts of aliphatic amine curing agent, 10 to 20 parts of polyether amine curing agent, 0.1 to 2 parts of tertiary amine curing accelerator, 20 to 50 parts of phenolic curing accelerator and 10 to 30 parts of reinforcing filler.

2. The solvent-free epoxy two-component coating adhesive according to claim 1, characterized in that: The epoxy resin is selected from at least one of epoxy resin E-44, epoxy resin E-51 and EPON 862 epoxy resin.

3. The solvent-free epoxy two-component coating adhesive according to claim 1, characterized in that: The toughening agent is selected from pure acrylate oligomers or epoxy acrylate oligomers.

4. The solvent-free epoxy two-component coating adhesive according to claim 1, characterized in that: The diluent is a high-boiling-point unsaturated acrylic ester active diluent.

5. The solvent-free epoxy two-component coating adhesive according to claim 1, characterized in that: The aliphatic amine curing agent is selected from 1,3-diaminomethylcyclohexane or N-aminoethylpiperazine.

6. The solvent-free epoxy two-component coating adhesive according to claim 1, characterized in that: The polyetheramine curing agent is selected from one or more of polyetheramine D230, D400 and D2000.

7. The solvent-free epoxy two-component coating adhesive according to claim 1, characterized in that: The reinforcing filler includes one or more of asbestos fiber, glass fiber, mica powder, aluminum powder, cement, porcelain powder, talcum powder, nano calcium carbonate powder, copper powder, iron powder, magnesium oxide, aluminum oxide, aluminum silicate, and titanium dioxide.

8. A method for preparing a solvent-free epoxy two-component coating adhesive, characterized in that: The method for preparing the solvent-free epoxy two-component coating adhesive according to claims 1 to 7 comprises the following steps: Step 1: Evenly mix epoxy resin, toughening agent, coupling agent and diluent to obtain component A; evenly mix aliphatic amine curing agent, polyether amine curing agent, tertiary amine curing accelerator and phenolic curing accelerator, and then add reinforcing filler and mix evenly to obtain component B; Step 2: Mix the component A and the component B described in step 1 in a mass ratio of A:B=1:0.8-1 to obtain a solvent-free epoxy two-component coating adhesive.

9. An application of a solvent-free epoxy two-component coating adhesive, characterized in that: The solvent-free epoxy two-component coating adhesive described in claims 1 to 7 is used for bonding a polymer film to a hard substrate.

10. The use of a solvent-free epoxy two-component coating adhesive according to claim 1, characterized in that: The polymer film is a flexible sheet structure with a thickness of 0.05 to 5 mm, and the hard substrate includes metal, glass, ceramic, bamboo, carbon fiber, glass fiber, hard foam, ABS, PVC, nylon, and plastic.

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