Adhesive for carton and preparation method thereof

Abstract

The invention belongs to the technical field of adhesives, and particularly relates to an adhesive for a carton and a preparation method of the adhesive, the adhesive is prepared from, by mass, 50-70 parts of epoxy resin, 5-10 parts of modified montmorillonite, 3-5 parts of curing agent, 10-15 parts of reactive diluent, 2-4 parts of antioxidant and 5-8 parts of polydopamine, and the specific preparation method is provided. The defect that a carton adhesive is mainly composed of starch glue is overcome, epoxy resin is matched with polydopamine to form a porous network structure, the adhesion of the adhesive is effectively improved, the problems of starch corrosion and the like do not exist, and the stability of the adhesive is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesives, and in particular relates to an adhesive for cartons and a preparation method thereof. Background Art

[0002] Packaging is an essential component of industrial development, and cartons have become a mainstream form of packaging. Cartons offer advantages such as lightweight, foldable, low-cost, environmentally friendly packaging, and highly adjustable specifications. Consequently, their application continues to expand. Adhesives are essential for carton production and use, primarily used for laminating paper or cardboard. Current carton adhesives are primarily based on starch glue. While low-cost and widely available, these glues have several drawbacks, such as weakening adhesion over time and poor moisture resistance. Summary of the Invention

[0003] In response to the problems in the prior art, the present invention provides an adhesive for carton, which solves the defect that carton adhesive is mainly composed of starch glue. The porous network structure is formed by combining epoxy resin with polydopamine, which not only effectively improves the adhesion of the adhesive, but also eliminates problems such as starch corruption, thereby ensuring the stability of the adhesive.

[0004] In order to achieve the above technical objectives, the technical solution of the present invention is:

[0005] An adhesive for carton, with a mass ratio of:

[0006] 50-70 parts of epoxy resin, 5-10 parts of modified montmorillonite, 3-5 parts of curing agent, 10-15 parts of active diluent, 2-4 parts of antioxidant, and 5-8 parts of polydopamine.

[0007] The epoxy resin is a mixture of epoxy resin E-51 and epoxy resin E-44, with a mass ratio of 2-3:2. Epoxy resin E-51 has a high content of epoxy groups and also exhibits good resin fluidity and permeability. Epoxy resin E-44 contains hydroxyl and epoxy groups, exhibiting good reactivity and minimal shrinkage. The mixture of epoxy resin E-51 and epoxy resin E-44 not only ensures the epoxy group content and reactivity of the epoxy resin, but also effectively controls the shrinkage of the adhesive, ensuring the bonding performance and stability of the epoxy resin.

[0008] The modified montmorillonite adopts polydopamine modified montmorillonite. Montmorillonite is a kind of soil-like mineral composed of nanometer-thick silicate sheets with negative surface charge, which are piled together by electrostatic interaction between layers. Although it is insoluble in water, it has good water absorption and its volume will expand rapidly when it encounters water, even up to 20 times its original size. Therefore, if montmorillonite is directly placed in the adhesive, the water absorption and expansion characteristics of montmorillonite will lead to a decrease in adhesion performance, and the absorption and penetration of bubbles and water will lead to the strengthening of molecular spacing, the direct increase of adhesion area, and the rapid decrease of adhesion strength. In response to this problem, montmorillonite needs to be modified. By modifying the montmorillonite, not only the spacing between the layered montmorillonite is increased to ensure stable ion replacement, but also dopamine is adsorbed to the montmorillonite interlayer under the condition of increased specific surface area and increased pore size. As the polymerization reaction proceeds, dopamine self-polymerizes to form polydopamine and is interspersed in the montmorillonite. Therefore, the modified montmorillonite exhibits an excellent network perforated structure. This treatment method not only solves the problem of water absorption and expansion of montmorillonite, but also utilizes the active groups of polydopamine to improve the surface activity of montmorillonite, which helps to disperse and fix it in epoxy resin adhesive.The preparation method of polydopamine-modified montmorillonite comprises the following steps: a1, soaking montmorillonite in water and ultrasonically treating it for 10-20 minutes, then spraying concentrated hydrochloric acid to adjust the pH, and filtering after standing to obtain acid-modified montmorillonite, wherein the mass ratio of the montmorillonite to water is 1:30-50, the temperature of the ultrasonic treatment is 40-50°C, the ultrasonic frequency is 70-100kHz, the pH of the concentrated hydrochloric acid is 1, the adjusted pH is 5-6, and the standing temperature is 30-50°C. In this step, the montmorillonite is soaked in water and ultrasonically treated to ensure that the montmorillonite is saturated with water, and the volume is reduced. The liquid expands to 20 times of its original size, and the entire liquid is converted to acidic by spraying concentrated hydrochloric acid, and the diffusion of hydrochloric acid in the water is used to slowly acidify the montmorillonite, and the montmorillonite is removed by filtration. At this time, the montmorillonite not only forms a swollen state after absorbing water, but also forms an acid-modified state inside. a2, dopamine is added to water and stirred until completely dissolved to obtain a dopamine aqueous solution, which is then mixed and stirred with the acid-modified montmorillonite, and filtered after standing for 2-4 hours to obtain dopamine-modified montmorillonite. The concentration of dopamine in water is 1.2-1.5 g / L, and the stirring speed is 500-800 r / min. The mass ratio of the dopamine aqueous solution to the acid-modified montmorillonite is 2-4:1, the mixing speed is 500-800 r / min, and the standing temperature is 30-50°C. This step utilizes the solubility of dopamine in water to form a dopamine solution. When the dopamine aqueous solution and the acid-modified montmorillonite are blended, the acid-modified montmorillonite at this time maintains its own structural expansion in a water-saturated state, and the dopamine aqueous solution will gradually penetrate into the montmorillonite. The internal weak acidic environment will promote the fixation of dopamine inside the montmorillonite, converting the acid-modified montmorillonite into dopamine-modified montmorillonite; a3, dissolving ammonium persulfate In water, and spray it onto the surface of dopamine-modified montmorillonite, keep it at a constant temperature for 1-2 hours, and dry it to obtain polydopamine-modified montmorillonite. The mass ratio of ammonium persulfate to water is 1:4-7, the spray amount is 2-4 mg / g, and the temperature of constant temperature is 30-40 ° C. This step utilizes the solubility of ammonium persulfate in water and sprays it directly onto the dopamine-modified montmorillonite in a spraying manner. At this time, the ammonium persulfate will directly penetrate into the interior and directly act on the dopamine. In the subsequent constant temperature standing, dopamine forms a stable in-situ self-polymerization between the montmorillonite layers, thereby achieving polydopamine-modified montmorillonite. The polydopamine-modified montmorillonite prepared by this method directly expands the montmorillonite by adsorbing water and forms an in-situ polymerization of polydopamine inside it, which not only reduces the hygroscopic expansion problem of the montmorillonite, but also intersperses the polydopamine between the layers to form a tight structure with the montmorillonite, showing a promoting effect on thermal stability, mechanical strength and chemical resistance. Polydopamine provides active groups, which can increase the active exposure of the montmorillonite surface and facilitate its active reaction in epoxy resin.

[0009] The curing agent is diethylenetriamine.

[0010] The active diluent is hexanediol diglycidyl ether.

[0011] The antioxidant is a mixture of 2,6-di-tert-butyl-p-cresol and diphenyl-n-octyl phosphite, and the mass ratio of 2,6-di-tert-butyl-p-cresol to diphenyl-n-octyl phosphite is 4:1-2.

[0012] The preparation method of the adhesive comprises the following steps:

[0013] Step 1: Place epoxy resin and active diluent into a reactor and stir at a constant temperature for 1-3 hours to obtain a premixture, wherein the constant temperature stirring temperature is 110-120° C.;

[0014] Step 2: adding a curing agent, modified montmorillonite and polydopamine into a reactor, and performing constant temperature ultrasonic dispersion for 20-30 minutes to obtain a mixture; the constant temperature ultrasonic dispersion temperature is 50-60° C., and the ultrasonic frequency is 70-100 kHz;

[0015] Step 3, stirring the mixture and the premixture at a constant temperature, then adding the antioxidant and stirring and mixing them uniformly to obtain the adhesive for carton, wherein the temperature of the constant temperature stirring is 30-40°C.

[0016] It can be seen from the above description that the present invention has the following advantages:

[0017] 1. The present invention solves the defect that carton adhesives are mainly starch glue. The porous network structure is formed by combining epoxy resin with polydopamine, which not only effectively improves the adhesion of the adhesive, but also eliminates the problem of starch corruption, thereby ensuring the stability of the adhesive.

[0018] 2. The present invention utilizes montmorillonite modification to fundamentally solve the hygroscopicity and hygroscopic expansion of montmorillonite, and converts montmorillonite into a layered porous filler, thereby greatly improving the compatibility of montmorillonite in the adhesive and effectively improving the mechanical properties.

[0019] 3. The present invention utilizes polydopamine, modified montmorillonite and a curing agent to form a multidimensional active amine, which can form a stable curing reaction with the epoxy resin and effectively improve the dispersibility of polydopamine and modified montmorillonite in the adhesive. DETAILED DESCRIPTION

[0020] The present invention is described in detail with reference to the embodiments, but no limitation is imposed on the claims of the present invention.

[0021] Example 1

[0022] An adhesive for carton, with a mass ratio of:

[0023] 50 parts of epoxy resin, 10 parts of modified montmorillonite, 3 parts of curing agent, 10 parts of active diluent, 2 parts of antioxidant, and 8 parts of polydopamine.

[0024] The epoxy resin is a mixture of epoxy resin E-51 and epoxy resin E-44, and the mass ratio of epoxy resin E-51 to epoxy resin E-44 is 1:1.

[0025] The modified montmorillonite adopts polydopamine-modified montmorillonite. The preparation method of the polydopamine-modified montmorillonite comprises the following steps: a1, soaking the montmorillonite in water and ultrasonically treating it for 10 minutes, then spraying concentrated hydrochloric acid to adjust the pH, and filtering after standing to obtain acid-modified montmorillonite, wherein the mass ratio of the montmorillonite to water is 1:50, the temperature of the ultrasonic treatment is 40°C, the ultrasonic frequency is 70kHz, the pH of the concentrated hydrochloric acid is 1, the adjusted pH is 5, and the standing temperature is 30°C; a2, adding dopamine to water and stirring until it is completely dissolved to obtain a dopamine aqueous solution, and then mixing with the acid-modified The montmorillonite was mixed and stirred, and then filtered after standing for 2 hours to obtain dopamine-modified montmorillonite, wherein the concentration of dopamine in water was 1.2 g / L, the stirring speed was 500 r / min, the mass ratio of the dopamine aqueous solution to the acid-modified montmorillonite was 4:1, the mixing and stirring speed was 500 r / min, and the standing temperature was 30°C; a3, ammonium persulfate was dissolved in water and sprayed onto the surface of the dopamine-modified montmorillonite, the mixture was stood at a constant temperature for 1 hour, and dried to obtain polydopamine-modified montmorillonite, the mass ratio of ammonium persulfate to water was 1:7, the spraying amount was 4 mg / g, and the standing temperature was 30°C.

[0026] The curing agent is diethylenetriamine.

[0027] The active diluent is hexanediol diglycidyl ether.

[0028] The antioxidant is a mixture of 2,6-di-tert-butyl-p-cresol and diphenyl-n-octyl phosphite, and the mass ratio of 2,6-di-tert-butyl-p-cresol to diphenyl-n-octyl phosphite is 4:1.

[0029] The preparation method of the adhesive comprises the following steps:

[0030] Step 1: placing epoxy resin and active diluent into a reactor and stirring at a constant temperature for 1 hour to obtain a premixture, wherein the constant temperature stirring temperature is 110° C.;

[0031] Step 2: adding a curing agent, modified montmorillonite and polydopamine into a reactor, and performing constant temperature ultrasonic dispersion for 20 minutes to obtain a mixture; the constant temperature ultrasonic dispersion temperature is 50° C., and the ultrasonic frequency is 70 kHz;

[0032] Step 3, the mixture and the premix are constant temperature stirred, then the antioxidant is added and stirred to be mixed uniformly, to obtain the paper box adhesive, the temperature of the constant temperature stirring is 30 DEG C.

[0033] Example 2

[0034] A paper box adhesive, the mass ratio is:

[0035] Epoxy resin 70 parts, modified montmorillonite 5 parts, curing agent 5 parts, active diluent 15 parts, antioxidant 4 parts, polydopamine 8 parts.

[0036] The epoxy resin uses a mixture of epoxy resin E-51 and epoxy resin E-44, and the mass ratio of epoxy resin E-51 to epoxy resin E-44 is 3:2.

[0037] The modified montmorillonite uses polydopamine modified montmorillonite, and the preparation method of the polydopamine modified montmorillonite comprises the following steps: a1, the montmorillonite is soaked in water and ultrasonic treated for 20 min, then the concentrated hydrochloric acid is sprayed to adjust the pH, after standing, the acid modified montmorillonite is obtained by filtration, the mass ratio of the montmorillonite to water is 1:30, the ultrasonic treatment temperature is 50 DEG C, the ultrasonic frequency is 100 kHz, the pH of the concentrated hydrochloric acid is 1, the adjusted pH is 6, and the standing temperature is 50 DEG C; a2, dopamine is added to water and stirred to completely dissolve to obtain a dopamine aqueous solution, then the acid modified montmorillonite is mixed and stirred, after standing for 4 h, the dopamine modified montmorillonite is obtained by filtration, the concentration of dopamine in water is 1.2 g / L, the stirring speed is 800 r / min, the mass ratio of the dopamine aqueous solution to the acid modified montmorillonite is 2:1, the mixing and stirring speed is 800 r / min, and the standing temperature is 50 DEG C; a3, ammonium persulfate is dissolved in water and sprayed on the surface of the dopamine modified montmorillonite, constant temperature standing for 2 h, and polydopamine modified montmorillonite is obtained by drying, the mass ratio of ammonium persulfate to water is 1:4, the spraying amount is 2 mg / g, and the constant temperature standing temperature is 40 DEG C.

[0038] The curing agent uses diethylene triamine.

[0039] The active diluent uses hexanediol diglycidyl ether.

[0040] The antioxidant uses a mixture of 2,6-di-tert-butyl-p-cresol and diphenyl n-octyl phosphite, and the mass ratio of 2,6-di-tert-butyl-p-cresol to diphenyl n-octyl phosphite is 2:1.

[0041] The preparation method of the adhesive comprises the following steps:

[0042] Step 1: placing epoxy resin and active diluent into a reactor and stirring at a constant temperature for 3 hours to obtain a premixture, wherein the constant temperature stirring temperature is 120° C.;

[0043] Step 2: adding a curing agent, modified montmorillonite and polydopamine into a reactor, and performing constant temperature ultrasonic dispersion for 30 minutes to obtain a mixture; the constant temperature ultrasonic dispersion temperature is 60° C., and the ultrasonic frequency is 100 kHz;

[0044] Step 3: Stir the mixture and the premixture at a constant temperature, then add the antioxidant and stir until uniformly mixed to obtain an adhesive for cartons, wherein the constant temperature stirring temperature is 40°C.

[0045] Example 3

[0046] An adhesive for carton, with a mass ratio of:

[0047] 60 parts of epoxy resin, 8 parts of modified montmorillonite, 4 parts of curing agent, 13 parts of active diluent, 3 parts of antioxidant, and 7 parts of polydopamine.

[0048] The epoxy resin is a mixture of epoxy resin E-51 and epoxy resin E-44, and the mass ratio of epoxy resin E-51 to epoxy resin E-44 is 3:2.

[0049] The modified montmorillonite adopts polydopamine-modified montmorillonite. The preparation method of the polydopamine-modified montmorillonite comprises the following steps: a1, soaking the montmorillonite in water and ultrasonically treating it for 15 minutes, then spraying concentrated hydrochloric acid to adjust the pH, and filtering after standing to obtain acid-modified montmorillonite, wherein the mass ratio of the montmorillonite to water is 1:40, the temperature of the ultrasonic treatment is 45°C, the ultrasonic frequency is 90kHz, the pH of the concentrated hydrochloric acid is 1, the adjusted pH is 5, and the standing temperature is 40°C; a2, adding dopamine to water and stirring until it is completely dissolved to obtain a dopamine aqueous solution, and then mixing with the acid-modified The montmorillonite was mixed and stirred, and then filtered after standing for 3 hours to obtain dopamine-modified montmorillonite, wherein the concentration of dopamine in water was 1.4 g / L, the stirring speed was 700 r / min, the mass ratio of the dopamine aqueous solution to the acid-modified montmorillonite was 3:1, the mixing and stirring speed was 600 r / min, and the standing temperature was 40°C; a3, ammonium persulfate was dissolved in water and sprayed onto the surface of the dopamine-modified montmorillonite, the mixture was stood at a constant temperature for 2 hours, and dried to obtain polydopamine-modified montmorillonite, the mass ratio of ammonium persulfate to water was 1:6, the spraying amount was 3 mg / g, and the constant standing temperature was 33°C.

[0050] The curing agent is diethylenetriamine.

[0051] The active diluent is hexanediol diglycidyl ether.

[0052] The antioxidant is a mixture of 2,6-di-tert-butyl-p-cresol and diphenyl-n-octyl phosphite, and the mass ratio of 2,6-di-tert-butyl-p-cresol to diphenyl-n-octyl phosphite is 4:1.

[0053] The preparation method of the adhesive comprises the following steps:

[0054] Step 1: placing epoxy resin and active diluent into a reactor and stirring at a constant temperature for 2 hours to obtain a premixture, wherein the constant temperature stirring temperature is 115° C.;

[0055] Step 2: adding a curing agent, modified montmorillonite and polydopamine into a reactor, and performing constant temperature ultrasonic dispersion for 25 minutes to obtain a mixture; the constant temperature ultrasonic dispersion temperature is 55° C., and the ultrasonic frequency is 90 kHz;

[0056] Step 3, stirring the mixture and the premixture at a constant temperature, then adding an antioxidant and stirring and mixing them uniformly to obtain an adhesive for cartons, wherein the constant temperature stirring temperature is 35°C.

[0057] Comparative Example 1

[0058] An adhesive for carton, with a mass ratio of:

[0059] 60 parts of epoxy resin, 8 parts of acid-modified montmorillonite, 4 parts of curing agent, 13 parts of active diluent, 3 parts of antioxidant, and 7 parts of polydopamine.

[0060] The epoxy resin is a mixture of epoxy resin E-51 and epoxy resin E-44, and the mass ratio of epoxy resin E-51 to epoxy resin E-44 is 3:2.

[0061] The preparation method of the acid dopamine-modified montmorillonite comprises the following steps: a1, soaking the montmorillonite in water and ultrasonically treating it for 15 minutes, then spraying concentrated hydrochloric acid to adjust the pH, and filtering after standing to obtain the acid-modified montmorillonite, wherein the mass ratio of the montmorillonite to water is 1:40, the ultrasonic treatment temperature is 45°C, the ultrasonic frequency is 90kHz, the pH of the concentrated hydrochloric acid is 1, the adjusted pH is 5, and the standing temperature is 40°C.

[0062] The curing agent is diethylenetriamine.

[0063] The active diluent is hexanediol diglycidyl ether.

[0064] The antioxidant is a mixture of 2,6-di-tert-butyl-p-cresol and diphenyl-n-octyl phosphite, and the mass ratio of 2,6-di-tert-butyl-p-cresol to diphenyl-n-octyl phosphite is 4:1.

[0065] The preparation method of the adhesive comprises the following steps:

[0066] Step 1: placing epoxy resin and active diluent into a reactor and stirring at a constant temperature for 2 hours to obtain a premixture, wherein the constant temperature stirring temperature is 115° C.;

[0067] Step 2: adding a curing agent, acid-modified montmorillonite and polydopamine into a reactor, and performing constant temperature ultrasonic dispersion for 25 minutes to obtain a mixture; the constant temperature ultrasonic dispersion temperature is 55° C. and the ultrasonic frequency is 90 kHz;

[0068] Step 3, stirring the mixture and the premixture at a constant temperature, then adding an antioxidant and stirring and mixing them uniformly to obtain an adhesive for cartons, wherein the constant temperature stirring temperature is 35°C.

[0069] Comparative Example 2

[0070] An adhesive for carton, with a mass ratio of:

[0071] 60 parts of epoxy resin, 8 parts of montmorillonite, 4 parts of curing agent, 13 parts of active diluent, 3 parts of antioxidant, and 7 parts of polydopamine.

[0072] The epoxy resin is a mixture of epoxy resin E-51 and epoxy resin E-44, and the mass ratio of epoxy resin E-51 to epoxy resin E-44 is 3:2.

[0073] The curing agent is diethylenetriamine.

[0074] The active diluent is hexanediol diglycidyl ether.

[0075] The antioxidant is a mixture of 2,6-di-tert-butyl-p-cresol and diphenyl-n-octyl phosphite, and the mass ratio of 2,6-di-tert-butyl-p-cresol to diphenyl-n-octyl phosphite is 4:1.

[0076] The preparation method of the adhesive comprises the following steps:

[0077] Step 1: placing epoxy resin and active diluent into a reactor and stirring at a constant temperature for 2 hours to obtain a premixture, wherein the constant temperature stirring temperature is 115° C.;

[0078] Step 2: adding a curing agent, montmorillonite and polydopamine into a reactor, and performing constant temperature ultrasonic dispersion for 25 minutes to obtain a mixture; the constant temperature ultrasonic dispersion temperature is 55° C., and the ultrasonic frequency is 90 kHz;

[0079] Step 3, stirring the mixture and the premixture at a constant temperature, then adding an antioxidant and stirring and mixing them uniformly to obtain an adhesive for cartons, wherein the constant temperature stirring temperature is 35°C.

[0080] Comparative Example 3

[0081] An adhesive for carton, with a mass ratio of:

[0082] 60 parts of epoxy resin, 8 parts of montmorillonite, 4 parts of curing agent, 13 parts of active diluent, and 3 parts of antioxidant.

[0083] The epoxy resin is a mixture of epoxy resin E-51 and epoxy resin E-44, and the mass ratio of epoxy resin E-51 to epoxy resin E-44 is 3:2.

[0084] The curing agent is diethylenetriamine.

[0085] The active diluent is hexanediol diglycidyl ether.

[0086] The antioxidant is a mixture of 2,6-di-tert-butyl-p-cresol and diphenyl-n-octyl phosphite, and the mass ratio of 2,6-di-tert-butyl-p-cresol to diphenyl-n-octyl phosphite is 4:1.

[0087] The preparation method of the adhesive comprises the following steps:

[0088] Step 1: placing epoxy resin and active diluent into a reactor and stirring at a constant temperature for 2 hours to obtain a premixture, wherein the constant temperature stirring temperature is 115° C.;

[0089] Step 2: adding a curing agent, montmorillonite and polydopamine into a reactor, and performing constant temperature ultrasonic dispersion for 25 minutes to obtain a mixture; the constant temperature ultrasonic dispersion temperature is 55° C., and the ultrasonic frequency is 90 kHz;

[0090] Step 3, stirring the mixture and the premixture at a constant temperature, then adding an antioxidant and stirring and mixing them uniformly to obtain an adhesive for cartons, wherein the constant temperature stirring temperature is 35°C.

[0091] Performance testing

[0092] The products of Examples 1-3 and Comparative Examples 1-3 were used as test samples for performance testing, and the results are as follows:

[0093]

[0094] Among them, the peel strength is tested using GB / T2790-1995 "Adhesive 180° Peel Strength Test Method Flexible Material to Rigid Material"; the wear index is tested using GB39601983 "Plastic Sliding Friction Wear Test Method"; the hydrophobicity test is to place 10g of adhesive in a humid environment and let it stand for 5 hours, and then weigh the mass of the adhesive after 5 hours to determine the adhesive condition; the tensile strength and weather resistance are tested using the CYT224-2020 "Adhesive Bonding Performance Requirements and Test Methods for Folding Cartons" method.

[0095] The above data show that the methods used in Examples 1-3, through the synergistic effect of polydopamine and polydopamine-modified montmorillonite, in combination with a curing agent, simultaneously solidify the epoxy resin and form a multidimensional network structure, effectively improving adhesion strength and stability. At the same time, the polydopamine modification method solves the montmorillonite's moisture absorption problem, ensuring the stability and adhesion of the adhesive. The acid-modified montmorillonite and montmorillonite in Comparative Examples 1-3 both have good adhesion. Materials such as epoxy resin have difficulty fully penetrating the interlayers. Combined with the excellent dispersibility of montmorillonite, the bubbles within the montmorillonite are distributed throughout the adhesive, resulting in a decrease in adhesion performance and mechanical strength. A comparison of Comparative Examples 2-3 demonstrates that the use of polydopamine can effectively improve adhesion strength.

[0096] It is understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced with equivalents to achieve the same technical effects; as long as the use requirements are met, they are all within the scope of protection of the present invention.

Claims

1. An adhesive for carton, characterized in that: The mass ratio is: 50-70 parts of epoxy resin, 5-10 parts of modified montmorillonite, 3-5 parts of curing agent, 10-15 parts of active diluent, 2-4 parts of antioxidant, and 5-8 parts of polydopamine.

2. The adhesive for carton according to claim 1, characterized in that: The epoxy resin is a mixture of epoxy resin E-51 and epoxy resin E-44.

3. The adhesive for carton according to claim 2, characterized in that: The mass ratio of the epoxy resin E-51 to the epoxy resin E-44 is 2-3:

2.

4. The adhesive for carton according to claim 1, characterized in that: The modified montmorillonite is polydopamine-modified montmorillonite.

5. The adhesive for carton according to claim 1, characterized in that: The curing agent is diethylenetriamine.

6. The adhesive for carton according to claim 1, characterized in that: The active diluent is hexanediol diglycidyl ether.

7. The adhesive for carton according to claim 1, characterized in that: The antioxidant is a mixture of 2,6-di-tert-butyl-p-cresol and diphenyl n-octyl phosphite.

8. The adhesive for carton according to claim 7, characterized in that: The mass ratio of the 2,6-di-tert-butyl-p-cresol to diphenyl n-octyl phosphite is 4:1-2.

9. The adhesive for carton according to claim 1, characterized in that: The preparation method of the adhesive comprises the following steps: Step 1: Place epoxy resin and active diluent into a reactor and stir at a constant temperature for 1-3 hours to obtain a premixture, wherein the constant temperature stirring temperature is 110-120° C.; Step 2: adding a curing agent, modified montmorillonite and polydopamine into a reactor, and performing constant temperature ultrasonic dispersion for 20-30 minutes to obtain a mixture; the constant temperature ultrasonic dispersion temperature is 50-60° C., and the ultrasonic frequency is 70-100 kHz; Step 3, stirring the mixture and the premixture at a constant temperature, then adding the antioxidant and stirring and mixing them uniformly to obtain the adhesive for carton, wherein the temperature of the constant temperature stirring is 30-40°C.

Images