An epoxy adhesive, its preparation method and application

Abstract

The application discloses an epoxy adhesive as well as a preparation method and application thereof. The adhesive comprises component A and component B. The component A comprises an epoxy resin, an active diluent, a reinforcing agent and a first filler. The component B comprises a modified amine curing agent, a first accelerator, a thickening agent, an oil absorbent and a second filler. The active diluent is selected from an epoxy soybean oil and / or an active cashew phenol diluent. Preferably, the active diluent is composed of the epoxy soybean oil and the active cashew phenol diluent, and the mass ratio of the epoxy soybean oil and the active cashew phenol diluent is (1-2):(1-3). The epoxy adhesive has good toughness, small odor and environmental protection, and can be used as an epoxy resin joint adhesive.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, and more specifically, relates to an epoxy adhesive, its preparation method, and its application. Background Technology

[0002] Joint sealant (also known in the market as joint compound, joint putty, crack-resistant sealant, etc.) is a widely used auxiliary material in painting projects. It is mainly used to bond and reinforce the joints between decorative panels and between panels and the substrate, preventing cracking. Various substrate cracking phenomena are common in building decoration, especially at the joints between different panel substrates. According to incomplete statistics, the actual cracking rate in each apartment unit reaches over 90%, with over 3% requiring repair. Traditional techniques and materials, such as kraft paper, mesh tape with white glue and cement, and elastic sealant, are not effective in preventing this cracking.

[0003] Joint adhesives offer superior bonding strength, excellent dimensional stability at joints, and resistance to deformation. They can bond to various substrates, effectively addressing common renovation problems such as cracking and deformation. Traditional joint materials typically include polyurethane, silicone, and acrylic types, but these generally suffer from drawbacks such as severe shrinkage, susceptibility to cracking, and strong odors. As people's living standards improve, their demands for living environments also increase, making green, environmentally friendly, non-toxic, odorless, and pollution-free home decoration materials crucial choices.

[0004] Epoxy resin joint adhesive is a common jointing material that can form strong adhesion between various materials, providing high-strength bonding. It also possesses excellent chemical stability, resisting corrosion from acids, alkalis, and salts, and exhibits good durability. Furthermore, epoxy resin joint adhesives have good crack resistance and no shrinkage, making them increasingly popular. Commercially available epoxy resin joint adhesives are generally room-temperature curing two-component adhesives. The mandatory national standard for building materials, GB / T 36797-2018 "Epoxy Resin Joint Adhesive for Anti-Cracking in Decoration," specifies its performance requirements. Currently, commercially available epoxy resin joint adhesives mainly suffer from poor toughness, strong odor, and high volatile content. Long-term use can not only seriously contaminate the bonded materials but also harm human health. Therefore, there is an urgent need to develop a more environmentally friendly and high-performance joint bonding material. Summary of the Invention

[0005] The purpose of this invention is to provide an epoxy adhesive, its preparation method, and its application. The epoxy adhesive of this invention has good toughness, low odor, and is environmentally friendly, and can be used as an epoxy resin joint adhesive.

[0006] To achieve the above objectives, a first aspect of the present invention provides an epoxy adhesive comprising component A and component B;

[0007] Component A includes: epoxy resin, reactive diluent, reinforcing agent, and first filler;

[0008] Component B comprises: a modified amine curing agent, a first accelerator, a thickener, an oil absorbent, and a second filler;

[0009] The active diluent is selected from epoxidized soybean oil and / or active cashew phenol diluent;

[0010] Preferably, the active diluent is composed of epoxidized soybean oil and active cashew phenol diluent, wherein the mass ratio of epoxidized soybean oil to active cashew phenol diluent is (1-2):(1-3).

[0011] The inventors discovered that commercially available two-component epoxy adhesives commonly use benzyl alcohol and glycidyl ether solvents as diluents. Benzyl alcohol, as a non-reactive diluent, does not participate in the cross-linking reaction and eventually migrates to the adhesive surface, reducing bond strength. While glycidyl ether solvents possess polymerization activity, they are highly toxic and have a strong odor, which is detrimental to the health of construction workers and environmental requirements. To minimize product odor and improve environmental friendliness, the epoxy adhesive prepared in this invention is a solvent-free system, preferably using a compound dilution system of epoxidized soybean oil and active cashew phenol diluent. Epoxidized soybean oil (ESO) contains epoxy groups in its molecular chain, possessing the advantages of low viscosity and non-toxic chemical properties. Blending ESO as an active diluent component into epoxy resin provides both plasticizing and diluting effects. However, while using only ESO can toughen epoxy materials, the viscosity of the mixture of ESO and epoxy resin is not as low as that of a mixture of other reactive diluents and epoxy resin. Therefore, it is preferable to use a combination of ESO and reactive cashew phenol diluent to combine the advantages of both. This dilution system ensures dilution while utilizing the ring-opening reaction between the epoxy groups in epoxidized soybean oil and reactive cashew phenol diluent to form a cross-linked network that strengthens the system's rigidity. At the same time, the long hydrophobic side chains in epoxidized soybean oil and reactive cashew phenol diluent impart good flexibility to the product, giving the epoxy material both toughness and strength.

[0012] According to the present invention, preferably, component A comprises, by weight parts: 30-40 parts epoxy resin, 5-10 parts reactive diluent, 10-20 parts reinforcing agent and 30-55 parts first filler;

[0013] By weight, component B comprises: 25-35 parts of modified amine curing agent, 1-5 parts of first accelerator, 2-8 parts of thickener, 2-6 parts of oil absorbent, and 45-65 parts of second filler;

[0014] Preferably, the mass ratio of component A to component B is (1-2):1.

[0015] In this invention, the unit mass parts of component A and component B may be the same or different.

[0016] According to the present invention, preferably, the modified amine curing agent is prepared by a method comprising the following steps: mixing an amino-terminated polyether and isophorone diamine; then adding a portion of hydrogenated epoxy resin, stirring and heating to 50-70°C, adding 1,3-cyclohexanedimethylamine, stirring and mixing, and then adding the remaining hydrogenated epoxy resin; adding an active cashew phenol diluent, a dispersant, and a second accelerator again, heating to 75-80°C, and stirring and mixing for 1-3 hours to obtain the modified amine curing agent;

[0017] Preferably, by mass parts, the amount of terminal amino polyether is 15-25 parts, the amount of isophorone diamine is 10-20 parts, the amount of 1,3-cyclohexanedimethylamine is 15-25 parts, the amount of active cashew nut phenol diluent is 25-40 parts, the amount of hydrogenated epoxy resin is 10-30 parts, the amount of second accelerator is 5-10 parts, and the amount of dispersant is 3-5 parts; the mass ratio of the partially hydrogenated epoxy resin to the isophorone diamine is (10-20):(5-10), and the mass ratio of the remaining hydrogenated epoxy resin to the 1,3-cyclohexanedimethylamine is (15-25):(5-20), preferably (1-3):1;

[0018] The dispersant is preferably a polycarboxylic acid ammonium salt and / or a polymeric block copolymer containing pigment affinity groups;

[0019] The second accelerator is preferably a polyetheramine accelerator and / or N-AEP.

[0020] In this invention, the amount of hydrogenated epoxy resin used is the sum of a portion of the hydrogenated epoxy resin and the remaining hydrogenated epoxy resin.

[0021] In this invention, the curing agent component uses a self-made solvent-free modified alicyclic amine curing agent, replacing the diluents used in traditional curing agent synthesis. It employs active cashew nut phenol diluent as a raw material, achieving a more environmentally friendly approach. The formulation system contains no volatile organic solvents, uses plant-based cashew nut phenol as a raw material, and can achieve extremely low VOC and zero formaldehyde emissions, while meeting the most stringent RoHS environmental standards.

[0022] According to the present invention, preferably, the epoxy resin comprises bisphenol A type epoxy resin and optionally dimer acid epoxy resin;

[0023] Preferably, the epoxy resin comprises bisphenol A type epoxy resin and dimer acid epoxy resin, wherein the mass ratio of the bisphenol A type epoxy resin and the dimer acid epoxy resin is (2-6):1.

[0024] In this invention, to improve the product's crack resistance, the epoxy resin is preferably a blend of bisphenol A type epoxy resin and low-viscosity dimer acid epoxy resin. The selected dimer acid epoxy resin has the characteristics of ultra-low viscosity, high activity, and high toughness. When used in combination with bisphenol A type epoxy resin, it can improve the product's resistance to thermal shock, resulting in good crack resistance in high and low temperature environments, small dimensional shrinkage of the cured product, high dimensional stability, and significantly improved adhesion and peel strength.

[0025] According to the present invention, preferably, the reinforcing agent is lignin.

[0026] In this invention, lignin is a biopolymer with a three-dimensional network structure formed by three phenylpropane units linked together by ether and carbon-carbon bonds. It contains abundant aromatic ring structures, aliphatic and aromatic hydroxyl groups, and quinone groups, among other active groups. Its blending with epoxy resin can significantly improve product rigidity, acting as a reinforcing agent. Lignin is mainly derived from agricultural waste such as straw and byproducts of the papermaking industry; it is inexpensive, readily available, and has good environmental compatibility, making it green and environmentally friendly. Its application makes the utilization of waste resources possible.

[0027] According to the present invention, preferably, the thickener is sodium carboxymethyl cellulose and / or sodium hydroxymethyl cellulose.

[0028] In this invention, to improve the applicability of the joint adhesive, sodium carboxymethyl cellulose, a natural pseudoplastic thickener, is selected. Its viscosity decreases with increasing shear stress, thereby improving coating performance and adhesion. At the same time, it gives the product a unique "granular feel," which is better than the granular effect brought by adding quartz sand, resulting in a better sensory experience during construction.

[0029] According to the present invention, preferably, the oil absorbent is sodium stearate and / or calcium stearate.

[0030] In this invention, sodium stearate / calcium stearate is used as an oil absorbent, which effectively prevents the product from separating and settling oil, and extends the shelf life.

[0031] According to the present invention, preferably, the first accelerator is a polyetheramine accelerator and / or N-AEP;

[0032] The first filler and the second filler are each independently at least one of modified silica powder, modified calcium powder and modified barium sulfate.

[0033] In this invention, the filler system uses modified filler compounding to effectively improve product sag and achieve the effect of non-sagging during application.

[0034] A second aspect of the present invention provides a method for preparing the above-mentioned adhesive, the method comprising:

[0035] Preparation of component A: The epoxy resin, reactive diluent, reinforcing agent and first filler are mixed evenly to obtain component A;

[0036] Preparation of component B: The modified amine curing agent, the first accelerator, the thickener, the oil absorbent, and the second filler are mixed evenly to obtain component B.

[0037] A third aspect of the present invention provides the application of the above-mentioned adhesive as a joint adhesive.

[0038] The technical solution of the present invention has the following beneficial effects:

[0039] (1) The epoxy adhesive of the present invention has good toughness, low odor and environmental protection, and can be used as epoxy resin joint adhesive.

[0040] (2) The epoxy adhesive of the present invention has extremely low odor and VOC, and the use of bio-based raw materials can achieve high environmental protection and zero formaldehyde release. The unique thickening system is more conducive to large-scale production and human health than the use of fumed silica, and there is no "pneumoconiosis" hazard; the use of sodium stearate / calcium stearate as an oil absorbent improves the product's oil separation and sedimentation, and enhances the product's storage stability; the unique plant-based dilution system, epoxy resin compounding system and self-made amine curing agent make the product both tough and strong, and the bonding strength and crack resistance are significantly improved.

[0041] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0042] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0043] Figure 1a and Figure 1b The storage stability test results of components A and B of Comparative Example 1, Test Example 2 according to the present invention, are shown in the figure.

[0044] Figure 2 The storage stability test results of component B of Comparative Example 2, Test Example 2 according to the present invention, are shown in the figure.

[0045] Figure 3a and Figure 3b The storage stability test results of components A and B in Example 2 of Test Example 2 according to the present invention are shown in the figure. Detailed Implementation

[0046] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0047] The present invention is further illustrated by the following examples:

[0048] In the following examples and comparative examples, the modified amine curing agents used were prepared by the following method:

[0049] Add the formulated amounts of terminal amino polyether and isophorone diamine to the reaction equipment and mix. Add a portion of the hydrogenated epoxy resin dropwise. While stirring, raise the temperature to 65°C. Continue stirring and add the formulated amounts of 1,3-cyclohexanedimethylamine. Mix thoroughly, then add the remaining hydrogenated epoxy resin, followed by the formulated amounts of active cashew nut phenol diluent, dispersant, and second accelerator. After the reaction temperature reaches 70°C, stir for 2 hours, and discharge under vacuum to obtain the modified amine curing agent. The amount of terminal amino polyether is 15 parts by weight, and the amount of isophorone diamine is... The following ingredients were used: 10 parts of 1,3-cyclohexanedimethylamine, 15 parts of 1,3-cyclohexanedimethylamine, 27 parts of active cashew nut phenol diluent, 25 parts of hydrogenated epoxy resin, 5 parts of the second accelerator, and 3 parts of dispersant. The mass ratio of partially hydrogenated epoxy resin to isophorone diamine was 1:1, and the mass ratio of the remaining hydrogenated epoxy resin to 1,3-cyclohexanedimethylamine was 1:1. The dispersant was ammonium polycarboxylate, purchased from Nopco Corporation, Japan, brand name SN5027; the amino-terminated polyether was purchased from Huntsman Corporation, brand name D220; and the hydrogenated epoxy resin was Idicco Hydrogenated Epoxy Resin 4080E, purchased from Idicco Corporation, Japan.

[0050] Both the first and second accelerators are N-AEP;

[0051] The active cashew phenol diluent is Cardlä NC-513;

[0052] Bisphenol A type epoxy resin was purchased from Nan Ya Epoxy Resin (Kunshan) Co., Ltd., with the grade E51.

[0053] The dimer acid epoxy resin is Senfida's 171;

[0054] Lignin was purchased from Wuxi Green Building Company;

[0055] The modified calcium powder is Jiangxi Hongyuan's 1250 active calcium;

[0056] The modified silica powder was 1250 mesh modified silica micro powder, purchased from Wuzhou Yingfeng Mining Company;

[0057] Modified barium sulfate was purchased from Shenzhen Haiyang Powder Co., Ltd., grade HY-A10;

[0058] Examples 1-5 provide an epoxy adhesive, the specific formulation of which is shown in Table 1 (the amounts of each raw material are parts by weight), and the specific preparation method is as follows:

[0059] Preparation of component A:

[0060] (1) Weigh the epoxy resin, reactive diluent, reinforcing agent and first filler according to the mass fraction ratio;

[0061] (2) Add epoxy resin and reactive diluent to the reaction vessel, stir and disperse evenly, add reinforcing agent, continue stirring, add the first filler, and disperse evenly to obtain component A;

[0062] Preparation of component B:

[0063] (1) Weigh the modified amine curing agent, the first accelerator thickener, the oil absorbent, and the second filler according to the mass ratio;

[0064] (2) First, add the modified amine curing agent and the first accelerator to the reactor, then add the second filler, and finally add the thickener and oil absorbent. After stirring evenly, component B is obtained.

[0065] Examples 1-5 were prepared according to a 2:1 mass ratio of components A and B.

[0066] Table 1

[0067]

[0068] Comparative Example 1

[0069] This comparison is based on a commercially available two-component joint sealant product; specifically, it is Carbon Gold All-Purpose Joint King from Fuzhou Wostun Coatings Technology Development Co., Ltd.

[0070] Comparative Example 2

[0071] The only difference between this comparative example and Example 2 is that 28 parts of modified amine curing agent in component B were replaced with 28 parts of MG-9110 modified fatty amine curing agent, which was purchased from Jiangsu Maigu Chemical Co., Ltd.

[0072] Test Example 1

[0073] The epoxy adhesives of the above embodiments and comparative examples were tested, and the specific test results are shown in Table 2. The odor rating evaluation method refers to: HG / T4065-2008, Odor Evaluation Method for Adhesives; Sagging, T-Impact Peel Length, Tensile Shear Strength, and Bond Strength refer to the Test Method for Undercoat in Table 2 of GB / T 36797-2018; The Total Volatile Organic Compounds (TVOC) determination method refers to: Appendix A of GB / T 36797-2018.

[0074] Table 2

[0075]

[0076]

[0077] Test results show that the epoxy adhesive prepared by this invention has significantly lower odor, lower VOC, and higher environmental friendliness compared with commercially available joint adhesives. At the same time, the product has better bonding strength, sag, and T-impact peel length.

[0078] Test Example 2

[0079] Storage stability tests were conducted on the epoxy adhesives of the above embodiments and comparative examples. The specific test method was as follows: components A and B of Example 2, Comparative Example 1 and Comparative Example 2 were placed in an oven at 60°C and stored for 10 days, and the changes in the products were observed.

[0080] like Figure 1a , Figure 1b , Figure 2 , Figure 3a and Figure 3b As shown, compared with component A of Example 2, component A of Comparative Example 1 showed obvious powder sedimentation and reduced thixotropy. Component B of both Comparative Example 1 and Comparative Example 2 showed varying degrees of oil separation and discoloration compared with component B of Example 2, with Comparative Example 1 showing more severe discoloration. Component B of Example 2 showed only slight yellowing and no obvious oil separation, indicating that its powder and liquid were better mixed and dispersed. Therefore, under the same storage conditions, the gel sample had better sensory properties and a longer storage time.

[0081] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An epoxy adhesive, characterized in that, The adhesive comprises component A and component B; Component A includes: epoxy resin, reactive diluent, reinforcing agent, and first filler; Component B comprises: a modified amine curing agent, a first accelerator, a thickener, an oil absorbent, and a second filler; The active diluent is selected from epoxidized soybean oil and / or active cashew phenol diluent; The modified amine curing agent is prepared by a method comprising the following steps: mixing terminal amino polyether and isophorone diamine; then adding a portion of hydrogenated epoxy resin, stirring and heating to 50-70°C, adding 1,3-cyclohexanedimethylamine, stirring and mixing, and then adding the remaining hydrogenated epoxy resin; adding active cashew phenol diluent, dispersant, and second accelerator again, heating to 75-80°C, and stirring and mixing for 1-3 hours to obtain the modified amine curing agent; The amount of terminal amino polyether is 15-25 parts, isophorone diamine is 10-20 parts, 1,3-cyclohexanedimethylamine is 15-25 parts, active cashew nut phenol diluent is 25-40 parts, hydrogenated epoxy resin is 10-30 parts, second accelerator is 5-10 parts, and dispersant is 3-5 parts, by mass. The mass ratio of the partially hydrogenated epoxy resin to the isophorone diamine is (10-20):(5-10), and the mass ratio of the remaining hydrogenated epoxy resin to the 1,3-cyclohexanedimethylamine is (15-25):(5-20).

2. The adhesive according to claim 1, wherein, The active diluent is composed of epoxidized soybean oil and active cashew phenol diluent, and the mass ratio of epoxidized soybean oil to active cashew phenol diluent is (1-2):(1-3).

3. The adhesive according to claim 1, wherein, The mass ratio of the remaining hydrogenated epoxy resin to the 1,3-cyclohexanedimethylamine is (1-3):

1.

4. The adhesive according to claim 1, wherein, By weight, component A comprises: 30-40 parts epoxy resin, 5-10 parts reactive diluent, 10-20 parts reinforcing agent, and 30-55 parts first filler; By weight, component B comprises: 25-35 parts of modified amine curing agent, 1-5 parts of first accelerator, 2-8 parts of thickener, 2-6 parts of oil absorbent, and 45-65 parts of second filler.

5. The adhesive according to claim 4, wherein, The mass ratio of component A to component B is (1-2):

1.

6. The adhesive according to claim 1 or 4, wherein, The dispersant is a polycarboxylic acid ammonium salt and / or a polymeric block copolymer containing pigment affinity groups; The second accelerator is a polyetheramine accelerator and / or N-AEP.

7. The adhesive according to claim 1 or 4, wherein, The epoxy resin includes bisphenol A type epoxy resin and optionally dimer acid epoxy resin.

8. The adhesive according to claim 7, wherein, The epoxy resin includes bisphenol A type epoxy resin and dimer acid epoxy resin, and the mass ratio of the bisphenol A type epoxy resin and dimer acid epoxy resin is (2-6):

1.

9. The adhesive according to claim 1 or 4, wherein, The reinforcing agent is lignin.

10. The adhesive according to claim 1 or 4, wherein, The thickener is sodium carboxymethyl cellulose and / or sodium hydroxymethyl cellulose.

11. The adhesive according to claim 1 or 4, wherein, The oil absorbent is sodium stearate and / or calcium stearate.

12. The adhesive according to claim 1 or 4, wherein, The first accelerator is a polyetheramine accelerator and / or N-AEP; The first filler and the second filler are each independently at least one of modified silica powder, modified calcium powder and modified barium sulfate.

13. A method for preparing the adhesive according to any one of claims 1-12, characterized in that, The preparation method includes: Preparation of component A: The epoxy resin, reactive diluent, reinforcing agent and first filler are mixed evenly to obtain component A; Preparation of component B: The modified amine curing agent, the first accelerator, the thickener, the oil absorbent, and the second filler are mixed evenly to obtain component B.

14. The use of the adhesive according to any one of claims 1-12 as a joint sealant.

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