High-stability low-exothermic structural adhesive system material, preparation method therefor and use thereof

Abstract

The present invention relates to the technical field of structural adhesives, and provides a high-stability low-exothermic structural adhesive system material, a preparation method therefor and a use thereof. The mass ratio of a resin component to a curing agent component in the structural adhesive system material is 10:(4-5). The resin component comprises 60-80 parts of bisphenol-A epoxy resin, 2-15 parts of bisphenol-F epoxy resin, 10-20 parts of an inorganic reinforcing filler, and 3-8 parts of a thickening thixotropic agent. The curing agent component comprises 56-115 parts of an amine curing agent, 5-20 parts of an inorganic reinforcing filler, 5-9 parts of a thickening thixotropic agent, and 4-60 parts of a modified amine-based rheology additive. The modified amine-based rheology additive is obtained by means of a pre-reaction, at a temperature of 25-150ºC, between an amine substance and a substance capable of undergoing an addition reaction with the amine substance. The present invention solves the problems of how to improve the stability of the structural adhesive and ensure smooth and uniform heat release during a curing exothermic process while meeting mechanical performance requirements.

Description

High-stability, low-exothermic structural adhesive system material and its preparation method and application

[0001] Cross-references

[0002] This application claims priority to Chinese application No. 2024103814005, filed on April 1, 2024. The contents of the above application are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of adhesives, and in particular to a high-stability, low-exothermic structural adhesive system material, a preparation method and application thereof. Background Art

[0004] Epoxy resins, due to their excellent mechanical properties, bonding properties, wear and chemical resistance after full cure, and minimal shrinkage during the curing process, have been widely used in various fields and have become the primary component of structural adhesives for wind turbine blades. Epoxy resins are linear or branched low-molecular substances that do not cure on their own. They must react with a curing agent under certain conditions to form a cross-linked network or bulk structure. This cross-linking of the epoxy resin and curing agent creates an insoluble, infusible structural adhesive that is useful in the bonding of wind turbine blades. Curing agents play a crucial role in epoxy resins, and the type and dosage of curing agent significantly influence the properties of the cured structural adhesive.

[0005] During the production process of wind turbine blades, the bonding area and bonding strength need to be ensured when the upper and lower shells are molded and bonded. The structural adhesive applied on the bonding surface must be full to avoid bonding defects such as glue shortage after mold closing, so as to ensure effective bonding between the shell and the web. Therefore, the structural adhesive is required to have a high shape retention ability while ensuring good fluidity during the gluing process at room temperature. At the same time, in order to reduce costs, improve product mechanical properties and dimensional stability during the curing process, it is usually necessary to add inorganic reinforcing fillers such as wollastonite, ground glass fiber, and calcium carbonate. Since the filler density is greater than the resin density, it is easy for the resin liquid to precipitate during storage, and the inorganic filler to settle and stratify, resulting in deviations in the mixing ratio when the structural adhesive is used, and it is impossible to achieve the ideal curing effect.

[0006] Thixotropy and storage stability are key performance characteristics not only for wind turbine structural adhesives, but also for adhesives, coatings, cosmetics, food, and many other fields. Common methods for improving filler settling in products include modifying the filler surface to enhance the interaction between the filler and the resin, adding rheological additives to improve filler dispersion, and adding thickeners to increase the viscosity of the continuous phase. However, modifying the filler surface not only increases product cost but also makes it difficult to ensure product batch stability. Moreover, commonly used anti-settling rheological additives are mostly solvents for polyamide or polyurea, which have certain adverse effects on the product's adhesive properties and TVOC.

[0007] For structural adhesives, the main component is active oligomers. Before curing, in order to prevent the oligomers from sagging or collapsing, inert thixotropic agents are usually used in related technologies to increase viscosity and provide optimal construction performance. Fillers with high specific surface areas such as fumed silica, fumed alumina and organic bentonite, when added in small amounts, can significantly increase the zero shear viscosity of oligomers, improve the anti-sagging properties of coatings and adhesives, and regulate their shear-thinning behavior. They are ideal thickening thixotropic agents. At the same time, the high specific surface area can also adsorb continuous phase liquids to prevent liquid precipitation and filler sedimentation. However, the inventors found that in order to achieve all of the above effects by adding such thickening thixotropic agents, the key is to effectively regulate the interactions between filler particles and between particles and the matrix, thereby obtaining a flocculated particle network structure. Liquid precipitation behavior cannot be completely solved by simply changing the surface properties of the filler.

[0008] In summary, existing structural adhesives in the domestic and international markets face challenges including cracking during transportation, crusting and caking, filler sedimentation, and liquid precipitation during long-term storage, an inability to meet various shape and size requirements during application, and intense heat release during curing. Therefore, while meeting mechanical performance requirements, improving the stability of structural adhesives and ensuring a smooth and uniform heat release during curing are pressing challenges in this field.

[0009] Therefore, there is an urgent need to develop a high-stability, low-exothermic structural adhesive system material and its preparation method and application to solve the above problems.

[0010] Summary of the Invention

[0011] The purpose of the present invention is to provide a high-stability, low-exothermic structural adhesive system material and its preparation method and application, which solves the problem of how to improve the stability of the structural adhesive and ensure smooth and uniform heat release during the curing heat release process while meeting the mechanical performance requirements.

[0012] To achieve the above objectives, in a first aspect, the present invention provides a high-stability, low-exothermic structural adhesive system, comprising a resin portion and a curing agent portion, wherein the mass ratio of the resin portion to the curing agent portion is 10:(4-5);

[0013] The resin part comprises, by weight, 60-80 parts of bisphenol A epoxy resin, 2-15 parts of bisphenol F epoxy resin, 10-20 parts of inorganic reinforcing filler, and 3-8 parts of thickening thixotropic agent;

[0014] The curing agent portion includes 56-115 parts of an amine curing agent, 5-20 parts of an inorganic reinforcing filler, 5-9 parts of a thickening thixotropic agent, and 4-60 parts of a modified amine rheological additive, and the liquid precipitation rate of the curing agent portion is lower than 2.0%; wherein, the modified amine rheological additive is obtained by pre-reacting an amine substance with a substance capable of undergoing an addition reaction with the amine substance at a temperature of 25-150° C., the amine substance includes at least one of polyetheramine, polyamide, and alicyclic amine, and the substance capable of undergoing an addition reaction with the amine substance includes at least one of isocyanate, extended chain isocyanate, epoxy resin, and extended chain epoxy resin.

[0015] Optionally, in the pre-reaction of the modified amine rheology modifier, the amount of the amine substance is 10-40 parts, and the amount of the substance capable of undergoing addition reaction with the amine substance is 5-15 parts.

[0016] Optionally, the amine curing agent contains 10-40 parts of polyetheramine and 30-40 parts of polyamide and / or alicyclic amine.

[0017] Optionally, the curing agent portion includes 40-70 parts of an amine curing agent, 5-20 parts of an inorganic reinforcing filler, 5-9 parts of a thickening thixotropic agent, and 4-60 parts of a modified amine rheological additive.

[0018] Optionally, the inorganic reinforcing filler includes at least one of ground glass fiber, wollastonite, calcium carbonate and fused silica.

[0019] Optionally, the thickening thixotropic agent includes at least one of fumed silica, fumed alumina and organic bentonite.

[0020] Optionally, the resin part further comprises 2-6 parts of a toughening agent and 0.05-0.2 parts of a defoaming agent.

[0021] In a second aspect, the present invention provides a method for preparing a high-stability, low-exothermic structural adhesive system material, comprising the following steps:

[0022] Preparing the resin part: preparing raw materials according to a ratio, and uniformly mixing the raw materials required for the resin part to obtain the resin part;

[0023] Preparation of the curing agent portion: P1, heating and mixing the amine substance and the substance capable of undergoing addition reaction with the amine substance in corresponding parts by weight at 25-150° C. for pre-reaction to obtain the modified amine rheological modifier; P2, taking corresponding parts by weight of the modified amine rheological modifier, adding the amine curing agent, the inorganic reinforcing filler, and the thickening thixotropic agent to the modified amine rheological modifier according to a proportion, and stirring at room temperature to obtain the curing agent portion;

[0024] The resin part and the curing agent part are mixed in a mass ratio of 10:(4-5) to obtain the structural adhesive system material. The exothermic peak temperature of the high-stability and low-exothermic structural adhesive system material is lower than 70°C, the gel time is greater than 220 minutes, and the curing time is greater than 500 minutes.

[0025] Optionally, in step P1: the substance capable of reacting with the amine substance is added dropwise to the amine substance, and stirred at 100° C. and a rotation speed of 100-2000 rpm for 30 minutes to obtain the modified amine rheological additive.

[0026] Optionally, in step P1: first mix the amine substances, then add the substance capable of undergoing addition reaction with the amine substances dropwise to the amine substances, and stir at 100° C. and a speed of 100-2000 rpm for 30 minutes to obtain the modified amine curing agent.

[0027] In a third aspect, the present invention provides an application of a high-stability, low-exothermic structural adhesive system material, which is used for bonding wind turbine blades.

[0028] Optionally, the application includes: performing a stress scanning test on the curing agent part to obtain a yield transition curve and a yield stress value of the curing agent part, and predicting the stability of the curing agent part. When the stress of the curing agent part is higher than the yield stress value, the yield transition curve will not show a sudden change, and the curing agent part will not crack.

[0029] The beneficial effects of the present invention include:

[0030] 1. The structural adhesive system material prepared by the preparation method of the present invention improves the stability of the curing agent part during transportation and storage, and will not crack, liquid precipitate and filler sedimentation.

[0031] 2. The structural adhesive system material prepared by the preparation method of the present invention reduces the heat released by the resin part and the curing agent part during the curing process, making the reaction heat release gentle and eliminating the high heat release peak.

[0032] 3. The modified amine rheological additive prepared by pre-reaction reduces the curing rate of the resin part and the curing agent part, and prolongs the operating time.

[0033] 4. The stress sweep test shows that even when the stress of the curing agent part is higher than the yield stress value, the yield transition curve of the curing agent part will not change suddenly, that is, the curing agent part will not crack during transportation and storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic flow chart of a method for preparing a high-stability, low-exothermic structural adhesive system material according to an embodiment of the present invention;

[0035] FIG2 is a graph showing shear viscosity versus stress for different samples of the present invention;

[0036] FIG3 is a graph showing the change in modulus over time for different samples of the present invention. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] The structural adhesive system material prepared by the preparation method of the present invention has good storage stability, excellent workability, long operation time, gentle curing exotherm and low exotherm peak, and excellent mechanical properties.

[0039] The present invention selects a high specific surface area filler with a high cost-effectiveness, and then adjusts the polarity of the oligomer matrix by synthesizing a modified amine rheological additive, thereby changing the thixotropy and yield transition process of the sample and improving the stability of the product. Adding the synthesized modified amine rheological additive to the amine curing agent can effectively and customizedly adjust the polarity of the oligomer matrix, thereby giving the structural adhesive product new rheological properties. The modified amine rheological additive is prepared by a synthetic reaction between an amine substance and a substance that can undergo an addition reaction with the amine substance (such as isocyanate, extended chain isocyanate, epoxy resin and extended chain epoxy resin). The modified amine rheological additive can not only improve the anti-sagging property, storage and transportation stability of the product, but also participate in the subsequent curing reaction and reduce the heat release of the structural adhesive curing reaction.

[0040] The present invention provides a high-stability and low-exothermic structural adhesive system material, comprising a resin part and a curing agent part, wherein the mass ratio of the resin part to the curing agent part is 10:(4-5);

[0041] The resin part comprises, by weight, 60-80 parts of bisphenol A epoxy resin, 2-15 parts of bisphenol F epoxy resin, 10-20 parts of inorganic reinforcing filler, and 3-8 parts of thickening thixotropic agent;

[0042] The curing agent portion includes 56-115 parts of an amine curing agent, 5-20 parts of an inorganic reinforcing filler, 5-9 parts of a thickening thixotropic agent, and 4-60 parts of a modified amine rheological additive, and the liquid precipitation rate of the curing agent portion is lower than 2.0%; wherein, the modified amine rheological additive is obtained by pre-reacting an amine substance with a substance capable of undergoing an addition reaction with the amine substance at a temperature of 25-150° C., the amine substance includes at least one of polyetheramine, polyamide, and alicyclic amine, and the substance capable of undergoing an addition reaction with the amine substance includes at least one of isocyanate, extended chain isocyanate, epoxy resin, and extended chain epoxy resin.

[0043] In some embodiments of the present invention, in the pre-reaction of the modified amine rheology modifier, the amount of the amine substance is 10-40 parts, and the amount of the substance capable of undergoing addition reaction with the amine substance is 5-15 parts.

[0044] In some embodiments of the present invention, the amine curing agent contains 10-40 parts of polyetheramine and 30-40 parts of polyamide and / or alicyclic amine.

[0045] In some embodiments of the present invention, the curing agent portion includes 40-70 parts of an amine curing agent, 5-20 parts of an inorganic reinforcing filler, 5-9 parts of a thickening thixotropic agent, and 4-60 parts of a modified amine rheological additive.

[0046] In some embodiments of the present invention, the inorganic reinforcing filler includes at least one of ground glass fiber, wollastonite, calcium carbonate and fused silica.

[0047] In some embodiments of the present invention, the thickening thixotropic agent includes at least one of fumed silica, fumed alumina, and organic bentonite.

[0048] In some embodiments of the present invention, the resin part further comprises 2-6 parts of a toughening agent and 0.05-0.2 parts of a defoaming agent.

[0049] The present invention provides a method for preparing a high-stability, low-exothermic structural adhesive system material, referring to FIG1 , comprising the following steps:

[0050] S1: preparing the resin part: preparing raw materials according to the ratio, and mixing the raw materials required for the resin part uniformly to obtain the resin part;

[0051] S2: preparing the curing agent portion: P1, heating and mixing the amine substance and the substance capable of undergoing addition reaction with the amine substance in corresponding parts by weight at 25-150° C. for pre-reaction to obtain the modified amine rheological modifier; P2, taking corresponding parts by weight of the modified amine rheological modifier, adding the amine curing agent, the inorganic reinforcing filler, and the thickening thixotropic agent to the modified amine rheological modifier according to a proportion, and stirring at room temperature to obtain the curing agent portion;

[0052] S3: The resin part and the curing agent part are mixed in a mass ratio of 10:(4-5) to obtain the structural adhesive system material. The exothermic peak temperature of the high-stability and low-exothermic structural adhesive system material is lower than 70°C, the gel time is greater than 230 minutes, and the curing time is greater than 500 minutes.

[0053] In some embodiments of the present invention, the pre-reaction time is 30-90 minutes.

[0054] In some embodiments of the present invention, in step P1, the substance capable of undergoing addition reaction with the amine substance is added dropwise to the amine substance, and stirred at 100° C. and 100-2000 rpm for 30 minutes to obtain the modified amine rheological additive.

[0055] In some embodiments of the present invention, in step P1: the amine substances are first mixed, and then the substance capable of undergoing an addition reaction with the amine substances is added dropwise to the amine substances, and stirred at 100° C. and a speed of 100-2000 rpm for 30 minutes to obtain the modified amine rheological additive.

[0056] The present invention provides an application of a high-stability and low-exothermic structural adhesive system material, wherein the structural adhesive system material is applied to the bonding of wind turbine blades.

[0057] In some embodiments of the present invention, the application includes: performing a stress scanning test on the curing agent part to obtain a yield transition curve and a yield stress value of the curing agent part, and predicting the stability of the curing agent part. When the stress of the curing agent part is higher than the yield stress value, the yield transition curve will not show a sudden change, and the curing agent part will not crack.

[0058] In some other specific embodiments of the present invention, the toughening agent and the defoaming agent are conventionally commercially available and will not be described in detail here.

[0059] In some embodiments of the present invention, the alicyclic amine includes isophoronediamine.

[0060] In some embodiments of the present invention, determining whether the curing agent part will crack can also be used to guide the optimization of the formula of the curing agent part, so as to adjust the formula of the curing agent part and optimize the process according to the state of the curing agent part at different test temperatures and the degree of defect improvement during the test process.

[0061] In some embodiments of the present invention, the constant temperature curing curve of the structural adhesive system material is measured by a rheometer, the curing rates of different structural adhesive system materials are compared, and the mechanical properties of the structural adhesive system material after curing are evaluated.

[0062] In some embodiments of the present invention, the epoxy equivalent weight of the bisphenol A epoxy resin is 170-240; and the epoxy equivalent weight of the bisphenol F epoxy resin is 160-180.

[0063] The manufacturers and models or brands of the instruments used in the embodiments of the present invention are shown in Table 1.

[0064] Table 1 Manufacturer and model or brand of instruments

[0065] The sources, English abbreviations and CAS numbers of the chemical reagents used in the embodiments of the present invention are shown in Table 2.

[0066] Table 2 Sources, English abbreviations and CAS numbers of chemical reagents Note: “--” in the table means none.

[0067] Example 1

[0068] Preparation of the resin portion: 65 parts of bisphenol A epoxy resin, 10 parts of bisphenol F epoxy resin, 15 parts of wollastonite, 5 parts of calcium carbonate, 5 parts of toughening agent and 0.2 parts of defoaming agent were mixed and stirred at room temperature to obtain the resin portion;

[0069] Preparation of modified amine rheological additive: 10 parts of bisphenol A epoxy resin were added dropwise to 10 parts of isophorone diamine, and stirred at 50°C and 200 rpm for 30 minutes to obtain a modified amine rheological additive;

[0070] Preparation of the curing agent: Add 10 parts of polyetheramine D230, 30 parts of polyetheramine D400, 30 parts of polyamide 350A, 5 parts of hydrophobic fumed silica, 10 parts of ground glass fiber and 5 parts of wollastonite to the modified amine rheological additive and stir at room temperature to obtain the curing agent;

[0071] The resin part and the curing agent part were mixed at a mass ratio of 2:1 at a rotation speed of 2000 rpm to obtain a structural adhesive system material sample.

[0072] Example 2

[0073] Preparation of the resin portion: 65 parts of bisphenol A epoxy resin, 10 parts of bisphenol F epoxy resin, 15 parts of wollastonite, 5 parts of calcium carbonate, 5 parts of toughening agent and 0.2 parts of defoaming agent were mixed and stirred at room temperature to obtain the resin portion;

[0074] Preparation of modified amine rheological additive: 10 parts of bisphenol A epoxy resin were added dropwise to 10 parts of isophorone diamine, and stirred at 100°C and 500 rpm for 30 minutes to obtain a modified amine rheological additive;

[0075] Preparation of the curing agent: Add 10 parts of polyetheramine D230, 30 parts of polyetheramine D400, 30 parts of polyamide 350A, 5 parts of hydrophobic fumed silica, 10 parts of ground glass fiber and 5 parts of wollastonite to the modified amine rheological additive and stir at room temperature to obtain the curing agent.

[0076] The resin part and the curing agent part were mixed at a mass ratio of 2:1 at a rotation speed of 2000 rpm to obtain a structural adhesive system material sample.

[0077] Example 3

[0078] Preparation of the resin portion: 65 parts of bisphenol A epoxy resin, 10 parts of bisphenol F epoxy resin, 15 parts of wollastonite, 5 parts of calcium carbonate, 5 parts of toughening agent and 0.2 parts of defoaming agent were mixed and stirred at room temperature to obtain the resin portion;

[0079] Preparation of modified amine rheological additive: 10 parts of bisphenol A epoxy resin were added dropwise to 30 parts of polyamide 350A, and stirred at 100°C and 2000 rpm for 60 minutes to obtain a modified amine rheological additive;

[0080] Preparation of the curing agent: Add 10 parts of isophorone diamine, 10 parts of polyetheramine D230, 30 parts of polyetheramine D400, 5 parts of hydrophobic fumed silica, 10 parts of ground glass fiber and 5 parts of wollastonite to the modified amine rheological additive and stir at room temperature to obtain the curing agent.

[0081] The resin part and the curing agent part were mixed at a mass ratio of 5:2 at a rotation speed of 2000 rpm to obtain a structural adhesive system material sample.

[0082] Example 4

[0083] Preparation of the resin portion: 65 parts of bisphenol A epoxy resin, 10 parts of bisphenol F epoxy resin, 15 parts of wollastonite, 5 parts of calcium carbonate, 5 parts of toughening agent and 0.2 parts of defoaming agent were mixed and stirred at room temperature to obtain the resin portion;

[0084] Preparation of modified amine rheological additive: 15 parts of bisphenol A epoxy resin were added dropwise to 30 parts of polyetheramine D400, and stirred at 120°C and 1000 rpm for 90 minutes to obtain a modified amine rheological additive;

[0085] Preparation of the curing agent: Add 10 parts of isophorone diamine, 10 parts of polyetheramine D230, 30 parts of polyamide 350A, 5 parts of hydrophobic fumed silica, 10 parts of ground glass fiber and 5 parts of wollastonite to the modified amine rheological additive and stir at room temperature to obtain the curing agent.

[0086] The resin part and the curing agent part were mixed at a mass ratio of 2:1 at a rotation speed of 2000 rpm to obtain a structural adhesive system material sample.

[0087] Example 5

[0088] Preparation of the resin portion: 65 parts of bisphenol A epoxy resin, 10 parts of bisphenol F epoxy resin, 15 parts of wollastonite, 5 parts of calcium carbonate, 5 parts of toughening agent and 0.2 parts of defoaming agent were mixed and stirred at room temperature to obtain the resin portion;

[0089] Preparation of modified amine rheological additive: 15 parts of IPDI were added dropwise to 30 parts of polyetheramine D400, and stirred at 90°C and 1000 rpm for 60 minutes to obtain a modified amine rheological additive;

[0090] Preparation of the curing agent: Add 10 parts of isophorone diamine, 10 parts of polyetheramine D230, 30 parts of polyamide 350A, 5 parts of hydrophobic fumed silica, 10 parts of ground glass fiber and 5 parts of wollastonite to the modified amine rheological additive and stir at room temperature to obtain the curing agent.

[0091] The resin part and the curing agent part were mixed at a mass ratio of 5:2 at a rotation speed of 2000 rpm to obtain a structural adhesive system material sample.

[0092] Example 6

[0093] Preparation of the resin portion: 65 parts of bisphenol A epoxy resin, 10 parts of bisphenol F epoxy resin, 15 parts of wollastonite, 5 parts of calcium carbonate, 5 parts of toughening agent and 0.2 parts of defoaming agent were mixed and stirred at room temperature to obtain the resin portion;

[0094] Preparation of a modified amine rheological additive: 5 parts of bisphenol A epoxy resin are dropwise added to 10 parts of isophorone diamine, followed by stirring at 100°C and 500 rpm for 30 minutes to obtain a first modified amine rheological additive; 10 parts of bisphenol A epoxy resin are dropwise added to 30 parts of polyetheramine D400, followed by stirring at 100°C and 500 rpm for 30 minutes to obtain a second modified amine rheological additive; the first modified amine rheological additive and the second modified amine rheological additive are uniformly mixed at room temperature to obtain a modified amine rheological additive;

[0095] Preparation of the curing agent: Add 10 parts of polyetheramine D230, 30 parts of polyamide 350A, 5 parts of hydrophobic fumed silica, 10 parts of ground glass fiber and 5 parts of wollastonite to the modified amine rheological additive and stir at room temperature to obtain the curing agent;

[0096] The resin part and the curing agent part were mixed at a mass ratio of 2:1 at a rotation speed of 2000 rpm to obtain a structural adhesive system material sample.

[0097] Example 7

[0098] Preparation of the resin portion: 65 parts of bisphenol A epoxy resin, 10 parts of bisphenol F epoxy resin, 15 parts of wollastonite, 5 parts of calcium carbonate, 5 parts of toughening agent and 0.2 parts of defoaming agent were mixed and stirred at room temperature to obtain the resin portion;

[0099] Preparation of a modified amine rheological modifier: 10 parts of isophorone diamine and 30 parts of polyetheramine D400 were mixed to obtain a first mixture, 15 parts of bisphenol A epoxy resin were dropwise added to the first mixture, and the mixture was stirred at 100° C. and 500 rpm for 30 minutes to obtain a modified amine rheological modifier;

[0100] Preparation of the curing agent: Add 10 parts of polyetheramine D230, 30 parts of polyamide 350A, 5 parts of hydrophobic fumed silica, 10 parts of ground glass fiber and 5 parts of wollastonite to the modified amine rheological additive and stir at room temperature to obtain the curing agent;

[0101] The resin part and the curing agent part were mixed at a mass ratio of 5:2 at a rotation speed of 2000 rpm to obtain a structural adhesive system material sample.

[0102] The components and their contents in Examples 1-7 are shown in Table 3.

[0103] Table 3 Components and contents of each example

[0104] Comparative Example 1

[0105] Preparation of the resin portion: 65 parts of bisphenol A epoxy resin, 10 parts of bisphenol F epoxy resin, 15 parts of wollastonite, 5 parts of calcium carbonate, 5 parts of toughening agent and 0.2 parts of defoaming agent were mixed and stirred at room temperature to obtain the resin portion;

[0106] Preparation of the curing agent: 10 parts of isophorone diamine, 10 parts of polyetheramine D230, 30 parts of polyetheramine D400, 30 parts of polyamide 350A, 5 parts of hydrophobic fumed silica, 10 parts of ground glass fiber and 5 parts of wollastonite were mixed and stirred at room temperature to obtain the curing agent.

[0107] The resin part and the curing agent part were mixed at a mass ratio of 2:1 at a rotation speed of 2000 rpm to obtain a comparative sample.

[0108] A stress scanning test was performed on the curing agent part of Examples 1-7 and Comparative Example 1 to obtain the yield transition process and yield stress value of the curing agent part. Referring to Figure 2, the rheological test results of the curing agent part of Examples 1-7 and Comparative Example 1 show that when the stress of the curing agent part of Comparative Example 1 is higher than the yield stress value, the shear viscosity shows a sudden change (discontinuous change process). Therefore, it can be judged that if the curing agent part of Comparative Example 1 is subjected to a force (surface force per unit area) greater than the yield stress value or the strain greater than the critical strain value during transportation, the curing agent part will crack. Although the yield transition behavior of Example 1 is smoother than that of Comparative Example 1, transportation cracking behavior may also occur in extreme cases. The yield transition processes of Examples 2-7 are relatively continuous and no transportation cracking behavior will occur.

[0109] [Corrected on 20.11.2024 according to Rule 91] The modulus of the structural adhesive system material samples of Examples 1-7 and the comparative sample of Comparative Example 1 were tested. Referring to Figure 3, the modulus change curves of the structural adhesive system material samples of Examples 1-7 and the comparative sample of Comparative Example 1 during the curing process are shown as a in FIG3 . The solid curve in FIG3 represents the storage modulus of the sample or comparative sample, and the hollow curve represents the loss modulus of the sample or comparative sample. Curves with the same geometric symbol shape represent the same sample or comparative sample. The gel point of the comparative sample of Comparative Example 1 appears at 180 min, and the gel point of the structural adhesive system material samples of Examples 1-7 appears after 225 min. The time to reach the gel point is the gel time. The gel time of the structural adhesive system material samples of Examples 1-7 and the comparative sample of Comparative Example 1 is shown in Table 4. The high stability and low exothermic structural adhesive system material of the present application reduces the curing rate of the resin part and the curing agent part, and prolongs the operable time.

[0110] For the system materials of Examples 1-7 and Comparative Example 1, the mechanical properties of the examples are not inferior to those of the comparative example. Referring to Table 4, the tensile strength of the bodies of Examples 1-7 tested according to ISO527-2 standard is slightly higher than that of Comparative Example 1.

[0111] The resin part and curing agent part of Examples 1-7 and Comparative Example 1 were subjected to storage stability tests, and the test method for the liquid precipitation rate was measured according to the test method described in patent CN116359450B: the resin part and the curing agent part were placed in a high-temperature and high-pressure reactor for high-temperature and high-pressure testing, the resin part and the curing agent part that had undergone the high-temperature and high-pressure test were taken out, and the liquid precipitation behavior of the resin part and the curing agent part was evaluated based on the liquid precipitation of the resin part and the curing agent part that had undergone the high-temperature and high-pressure test. The pressure of the high-temperature and high-pressure test was 0.2-6 MPa, the temperature of the high-temperature and high-pressure test was 25-100°C, and the time of the high-temperature and high-pressure test was 4-96 hours. The liquid precipitation rate of the resin part and the curing agent part, that is, the proportion of the precipitated liquid, is calculated as follows: z is the proportion of precipitated liquid, in %, y is the weight of precipitated liquid, in g, and w is the weight of the sample to be evaluated, in g. The heat release during the curing process of the structural adhesive system material samples of Examples 1-7 and the comparative sample of Comparative Example 1 was monitored and a constant temperature curing test was performed using a rheometer. The test results are shown in Table 4.

[0112] Table 4

[0113] As can be seen from Table 4, the storage stability of the resin part of the examples and comparative example 1 is good, and the stability of the curing agent part of examples 4-7 is good, while the liquid precipitation behavior of the curing agent part of comparative example 1 is more serious. Therefore, it can be judged that the occurrence of the pre-reaction changes the structure of the molecular chain and affects the interaction between the curing agent part and the gas silicon, thereby avoiding the occurrence of liquid precipitation behavior; the curing temperature of examples 1-7 is significantly lower than the exothermic temperature of comparative example 1, which shows that pre-reacting the curing agent part can significantly reduce the heat released during the curing process after mixing; and the gelation time and curing time of examples 1-7 are significantly longer than those of comparative example 1, indicating that the design of the pre-reaction process significantly reduces the curing rate of the structural adhesive system material and extends the operating time.

[0114] While the embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations of these embodiments are possible. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the claims. Furthermore, the invention described herein is susceptible to other embodiments and may be practiced or implemented in a variety of ways.

Claims

1. A high stability and low exothermic structural adhesive system material, characterized in that: Comprising a resin portion and a curing agent portion, wherein the mass ratio of the resin portion to the curing agent portion is 10:(4-5); The resin part comprises, by weight, 60-80 parts of bisphenol A epoxy resin, 2-15 parts of bisphenol F epoxy resin, 10-20 parts of inorganic reinforcing filler, and 3-8 parts of thickening thixotropic agent; The curing agent portion includes 56-115 parts of an amine curing agent, 5-20 parts of an inorganic reinforcing filler, 5-9 parts of a thickening thixotropic agent, and 4-60 parts of a modified amine rheological additive. The liquid precipitation rate of the curing agent portion is lower than 2.0%. The modified amine rheological additive is obtained by pre-reacting an amine substance with a substance capable of undergoing an addition reaction with the amine substance at a temperature of 25-150° C., the amine substance includes at least one of polyetheramine, polyamide, and alicyclic amine, and the substance capable of undergoing an addition reaction with the amine substance includes at least one of isocyanate and epoxy resin.

2. The high stability and low exothermic structural adhesive system according to claim 1, characterized in that: In the pre-reaction of the modified amine rheological additive, the amount of the amine substance is 10-40 parts, and the amount of the substance capable of reacting with the amine substance is 5-15 parts.

3. The high stability and low exothermic structural adhesive system according to claim 1, characterized in that: The amine curing agent contains 10-40 parts of polyetheramine and 30-40 parts of polyamide and / or alicyclic amine.

4. The high stability and low exothermic structural adhesive system according to claim 1, characterized in that: The curing agent part includes 40-70 parts of an amine curing agent, 5-20 parts of an inorganic reinforcing filler, 5-9 parts of a thickening thixotropic agent and 4-60 parts of a modified amine rheological additive.

5. The high stability and low exothermic structural adhesive system according to claim 1, characterized in that: The inorganic reinforcing filler includes at least one of ground glass fiber, wollastonite, calcium carbonate and fused silica.

6. The high stability and low exothermic structural adhesive system according to claim 1, characterized in that: The thickening thixotropic agent includes at least one of fumed silica, fumed alumina and organic bentonite.

7. The high stability and low exothermic structural adhesive system according to claim 1, characterized in that: The resin part also includes 2-6 parts of toughening agent and 0.05-0.2 parts of defoaming agent.

8. A method for preparing a high-stability, low-exothermic structural adhesive system according to any one of claims 1 to 7, characterized in that: The following steps are involved: Preparing the resin part: preparing raw materials according to a ratio, and uniformly mixing the raw materials required for the resin part to obtain the resin part; Preparation of the curing agent portion: P1, heating and mixing the amine substance and the substance capable of undergoing addition reaction with the amine substance in corresponding parts by weight at 25-150° C. for pre-reaction to obtain the modified amine rheological modifier; P2, taking corresponding parts by weight of the modified amine rheological modifier, adding the amine curing agent, the inorganic reinforcing filler, and the thickening thixotropic agent to the modified amine rheological modifier according to a proportion, and stirring at room temperature to obtain the curing agent portion; The resin part and the curing agent part are mixed in a mass ratio of 10:(4-5) to obtain the high-stability, low-exothermic structural adhesive system material. The high-stability, low-exothermic structural adhesive system material has an exothermic peak temperature lower than 70°C, a gel time greater than 230 minutes, and a curing time greater than 500 minutes.

9. The method for preparing a high-stability, low-exothermic structural adhesive system according to claim 8, characterized in that: In the step P1, the substance capable of reacting with the amine substance is added dropwise to the amine substance, and the mixture is stirred at 100° C. and a rotation speed of 100-2000 rpm for 30 minutes to obtain the modified amine rheological additive.

10. The method for preparing a high-stability, low-exothermic structural adhesive system according to claim 8, characterized in that: In the step P1, the amine substances are first mixed, and then the substance capable of undergoing addition reaction with the amine substances is added dropwise to the amine substances, and stirred at 100° C. and a speed of 100-2000 rpm for 30 minutes to obtain the modified amine rheological additive.

11. Use of the high stability and low exothermic structural adhesive system according to any one of claims 1 to 7, characterized in that: The structural adhesive system material is used for bonding wind turbine blades.

12. The use of the high stability and low exothermic structural adhesive system according to claim 11, characterized in that: include: A stress scanning test is performed on the curing agent part to obtain the yield transition curve and yield stress value of the curing agent part, and the stability of the curing agent part is predicted. When the stress of the curing agent part is higher than the yield stress value, the yield transition curve will not show a sudden change, and the curing agent part will not crack.

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