A coating material containing a flexible chain segment epoxy resin and a method for producing the same

Abstract

The application provides a flexible chain segment-containing epoxy resin intermediate coating and a preparation method thereof, the method comprises the following steps: uniformly mixing triethylenetetramine and dimer acid in a mass ratio of 1:(0.3-0.6), then reacting at 140-145 DEG C and cooling, then adding epoxy resin and terminal olefin polyether into the obtained reaction solution in sequence, and finally uniformly dispersing with deionized water to obtain a dimer acid modified epoxy resin curing agent; diluting the curing agent with deionized water to obtain a dispersion, then adding epoxy resin to emulsify, then diluting with deionized water, uniformly dispersing the obtained emulsion, and obtaining an epoxy resin emulsion; uniformly mixing the epoxy resin emulsion, quartz sand and cement to obtain an epoxy mortar, and standing the epoxy mortar to obtain the flexible chain segment-containing epoxy resin intermediate coating, which has impact resistance, high toughness and certain hydrophobicity.

Description

Technical Field

[0001] This invention belongs to the field of epoxy resin floor coating preparation, and specifically relates to an epoxy resin intermediate coating containing flexible segments and its preparation method. Background Technology

[0002] Epoxy resin is widely used in aerospace, coatings, construction, automotive, and electronics industries due to its advantages such as good corrosion resistance, strong adhesion, high bonding strength, low shrinkage, and stable chemical properties. Water-based epoxy resin floor coatings are produced by dispersing epoxy resin in water as a solvent, and then mixing it with a curing agent and aggregate in different proportions to form a primer, intermediate coat, and topcoat. These are then brushed onto the substrate surface in sequence. The intermediate coat requires the use of quartz sand and cement, primarily to provide the floor coating with certain compressive strength and impact resistance.

[0003] Epoxy resin cured in cement and quartz sand forms a mid-coat coating. Its high-strength molecular network structure enhances the compressive strength of the cement. However, due to the presence of rigid and polar groups on the epoxy resin molecular backbone, the epoxy resin as a whole exhibits rigidity, resulting in a deficiency in toughness and impact resistance. Since current floor coatings are commonly used in parking lots, factories, and similar areas, these coatings, subjected to prolonged vehicle and heavy object pressure, are highly susceptible to cracking and damage due to their lack of toughness and impact resistance. Because the three-dimensional network structure of the mid-coat is formed by the polymerization reaction of epoxy monomers and a curing agent, its performance primarily depends on the structure of both the epoxy resin and curing agent components. Therefore, the development of functional epoxy curing agents is crucial for creating high-performance, widely applicable waterborne epoxy resin mid-coats. Increasing the molecular chain length and flexibility allows epoxy resin molecules to maintain a certain degree of mobility after curing. This mobility enables the epoxy resin to effectively disperse external forces after being subjected to severe impacts, resulting in good toughness and impact resistance.

[0004] There are reports of using dimer acids to modify E51 type epoxy resin. The prepared epoxy resin intermediate coating has increased flexibility and impact resistance, but its water solubility is insufficient. In addition, the use of organic solvents to disperse epoxy resin coatings can cause harm to human health during long-term use due to the volatilization of organic solvents. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides an epoxy resin intermediate coating containing flexible segments and its preparation method. The epoxy resin is cured with an epoxy resin curing agent containing flexible segments. By changing the flexibility and hydrophilicity of the epoxy resin molecular chain, the properties of the cured epoxy resin and the epoxy resin intermediate coating are controlled. The resulting epoxy resin intermediate coating has impact resistance, high toughness, and a certain degree of hydrophobicity.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing an epoxy resin intermediate coating containing flexible segments includes the following steps:

[0008] Step 1: Mix triethylenetetramine and dimer acid at a mass ratio of 1:(0.3-0.6) until homogeneous. Then react at 140-145℃ and cool down. Next, add epoxy resin and terminal olefin polyether to the resulting reaction solution in sequence. Finally, disperse the mixture evenly with deionized water to obtain dimer acid modified epoxy resin curing agent.

[0009] Step 2: Dilute the dimer acid modified epoxy resin curing agent with deionized water to obtain a dispersion, then add epoxy resin for emulsification, and then add deionized water for dilution. Once the resulting emulsion is evenly dispersed, an epoxy resin emulsion is obtained.

[0010] Step 3: Mix epoxy resin emulsion, quartz sand, and cement evenly to obtain epoxy mortar. Let the epoxy mortar stand to obtain epoxy resin intermediate coating containing flexible segments.

[0011] Preferably, the epoxy resin mentioned in steps 1 and 2 is E51 type epoxy resin.

[0012] The terminal olefin polyether mentioned in step 1 is of type 91-B.

[0013] Preferably, the triethylenetetramine and dimer acid described in step 1 are stirred and reacted at 140-145°C for 3.5-4.5 hours, then cooled to 70-80°C, and then epoxy resin and terminal olefin polyether are added sequentially.

[0014] Further, in step 1, the epoxy resin is dissolved in diethylene glycol dibutyl ether, and the resulting solution is added dropwise to the reaction solution. The mass ratio of epoxy resin, diethylene glycol dibutyl ether, and triethylenetetramine is 1.1:0.1:1, and the dropping rate is 0.4-0.6 ml / min.

[0015] Preferably, in step 1, after adding epoxy resin, stir for 2.5-3.5 hours, then add terminal olefin polyether, with a mass ratio of terminal olefin polyether to triethylenetetramine of 6.8:1, keep warm for 2-3 hours, and finally disperse evenly with deionized water to obtain dimer acid modified epoxy resin curing agent.

[0016] Preferably, the mass ratio of deionized water to triethylenetetramine in step 1 is 2.9:1;

[0017] In step 2, the mass ratio of the first added deionized water to the dimer acid modified epoxy resin curing agent is 1:1, and the second added deionized water accounts for 25% of the total mass of the dispersion and epoxy resin.

[0018] Preferably, the mass ratio of epoxy resin and dimer acid modified epoxy resin curing agent in step 2 is 1:3.

[0019] Preferably, the quartz sand mentioned in step 3 is divided into 40-70 mesh quartz sand and 80-120 mesh quartz sand, and the mass ratio of 40-70 mesh quartz sand, 80-120 mesh quartz sand, cement and dimer acid modified epoxy resin curing agent in step 2 is 3:3:2:6.

[0020] Preferably, in step 3, the epoxy mortar is allowed to stand for 3.5-4.5 hours to obtain an intermediate coating containing flexible segment epoxy resin.

[0021] A flexible segment epoxy resin intermediate coating obtained by the preparation method of any one of the above-described epoxy resin intermediate coatings.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] This invention discloses a method for preparing a mid-coat epoxy resin containing flexible segments. Using triethylenetetramine (a polyamine) as the matrix, it is modified with dimer acid, epoxy resin, and terminal olefin polyether to obtain a dimer acid-modified epoxy resin curing agent. Dimer acid is a macromolecular long-chain dicarboxylic acid. On the one hand, it can enhance the length and flexibility of the epoxy resin molecular chain. The long, flexible carbon chains, after being introduced into the epoxy resin, allow the cured epoxy resin molecular chains to retain a certain degree of mobility. On the other hand, it allows the epoxy resin to quickly disperse the impact force after being subjected to external impact, exhibiting good impact resistance and toughness. Furthermore, the longer hydrophobic segments of dimer acid can endow the polyamine curing agent with emulsifying ability, enabling the epoxy resin to adhere more effectively to cement and quartz sand in aqueous solvents. Simultaneously, the long carbon chain, acting as a hydrophobic segment, reacts with triethylenetetramine to generate a surfactant with one hydrophilic end and one hydrophobic end, endowing it with emulsifying ability. This allows for better encapsulation and emulsification of epoxy resin monomers in aqueous solutions, resulting in improved water dispersibility and better curing in cement. Introducing epoxy resin into the curing agent effectively enhances the compatibility and emulsifying ability between the curing agent and epoxy resin, making the latex particles formed by the epoxy resin in aqueous solutions more stable. Terminal olefin polyethers, being hydrophilic functional monomers, further enhance the hydrophilicity and emulsifying ability of the curing agent upon addition. This invention uses water as a solvent to disperse epoxy resin, replacing traditional organic solvents. In subsequent use, this reduces the volatilization of organic solvents into the air, resulting in less environmental pollution and promoting the sustainable development of epoxy resin intermediate coatings.

[0024] This invention uses organic epoxy resin to reinforce and toughen inorganic materials such as cement and quartz sand, significantly improving their mechanical properties. The intermediate coating containing flexible segment epoxy resin has a moderate viscosity, meeting construction requirements, and good compatibility with cement and quartz sand. The coating surface is smooth and has good flexibility and impact resistance after curing, and its hydrophobicity is improved to a certain extent, giving it a wider range of application prospects in the intermediate coating industry. Attached Figure Description

[0025] Figure 1 The image shows the FTIR spectrum of the dimer acid-modified epoxy resin curing agent obtained in Example 1 of this invention.

[0026] Figure 2a The TGA curve of the epoxy resin containing flexible segments obtained in Example 1 of this invention is shown.

[0027] Figure 2b This is the DSC curve of the epoxy resin containing flexible segments obtained in Example 1 of this invention.

[0028] Figure 3 The rheological curve of the epoxy mortar containing flexible segments obtained in Example 1 of this invention is shown.

[0029] Figure 4 This invention describes the preparation mechanism of the epoxy resin intermediate coating containing flexible segments.

[0030] Figure 5 Compression performance tests were conducted on ordinary epoxy resin intermediate coatings and the epoxy resin intermediate coating containing flexible segments obtained in Example 1 of this invention.

[0031] Figure 6a This test assesses the impact resistance of ordinary epoxy resin intermediate coatings.

[0032] Figure 6b This is a test of the impact resistance of the epoxy resin intermediate coating containing flexible segments obtained in Example 1 of the present invention.

[0033] Figure 7a This is a schematic diagram of the contact angle of a common epoxy resin intermediate coating.

[0034] Figure 7b This is a schematic diagram of the contact angle of the epoxy resin intermediate coating containing flexible segments obtained in Example 1 of the present invention. Detailed Implementation

[0035] The present invention will be described in detail below with reference to implementation examples. The description in this section is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0036] This invention discloses a flexible segment epoxy resin intermediate coating, comprising component I, component II, cement, quartz sand (40-70 mesh), and quartz sand (80-120 mesh). The cement is silicate cement, and its main component is calcium silicate.

[0037] Component I is a dimer acid-modified epoxy resin curing agent, and component II is E51 type epoxy resin.

[0038] The mass ratio of component I, component II, cement, and quartz sand (40-70 mesh) to quartz sand (80-120 mesh) is 6:2:2:3:3.

[0039] The dimer acid modified epoxy resin curing agent is prepared from triethylenetetramine, dimer acid, E51 type epoxy resin, diethylene glycol dibutyl ether, terminal olefin polyether of type 91-B, and deionized water. The mass ratio of triethylenetetramine, dimer acid, E51 type epoxy resin, diethylene glycol dibutyl ether, terminal olefin polyether 91-B, and deionized water is 1:(0.3-0.6):1.1:0.1:6.8:2.9.

[0040] This invention discloses a method for preparing an epoxy resin intermediate coating containing flexible segments, comprising the following steps:

[0041] Step 1: Preparation of Dimer Acid Modified Epoxy Resin Curing Agent

[0042] Triethylenetetramine and dimer acid were mixed evenly at a mass ratio of 1:(0.3-0.6). The mixture was then stirred at 140-145℃ for 3.5-4.5 hours, followed by cooling to 70-80℃. A solution of E51 type epoxy resin diluted with diethylene glycol dibutyl ether solvent was then added dropwise at a rate of 0.4-0.6 ml per minute. The mixture was stirred for 2.5-3.5 hours, followed by the addition of terminal olefin polyether of type 91-B. The mixture was kept at this temperature for 2-3 hours, and finally deionized water was added to disperse the mixture evenly. This resulted in a reddish-brown, transparent, viscous dimer acid-modified epoxy resin curing agent, which is an epoxy resin curing agent containing flexible segments and is designated as DTEB.

[0043] Step 2: Preparation of epoxy resin emulsion

[0044] (1) Add the curing agent DTEB to an equal mass of deionized water to dilute and prepare a dispersion.

[0045] (2) Slowly pour the dispersion prepared in (1) into E51 epoxy resin and stir to emulsify. Then add 25% of the total mass of the dispersion and E51 epoxy resin with deionized water for dilution. When the emulsion is evenly dispersed and there are no oil droplets, an epoxy resin emulsion is obtained. In order to facilitate the later testing of its performance, take a part of the epoxy resin emulsion and let it stand at room temperature. In this way, a flexible segment epoxy resin is obtained and recorded as E51-DTEB.

[0046] Step 3: Preparation of intermediate coating with flexible segment epoxy resin

[0047] Quartz sand (40-70 mesh), quartz sand (80-120 mesh), and cement are added to the emulsion obtained in step two and stirred evenly to obtain epoxy mortar. After standing for 3.5-4.5 hours to cure, a mid-coat coating containing flexible segment epoxy resin with a density of 0.238-0.242 g / cm³ is obtained. 3 .

[0048] Example 1

[0049] Weigh 29.2g of triethylenetetramine and 16.9g of dimer acid and mix them evenly in a three-necked flask. Stir at 145℃ for 4 hours, then cool to 75℃. Add 36.6g of diethylene glycol dibutyl ether solution of E51 type epoxy resin at a dropping rate of 0.5ml per minute. Stir for 3 hours, then add 20g of terminal olefin polyether 91-B and keep warm for 2.5 hours. Finally, add 84.72g of deionized water to disperse and obtain a reddish-brown transparent viscous dimer acid modified epoxy resin curing agent DTEB.

[0050] Weigh 15g of curing agent DTEB, add 15g of deionized water for dilution, slowly pour in 10g of E51 type epoxy resin and stir to emulsify, then add 10g of deionized water for dilution. After the emulsion is evenly dispersed and there are no oil droplets, take a portion of the epoxy resin emulsion and let it stand at room temperature to cure to obtain epoxy resin E51-DTEB containing flexible chain segments.

[0051] Take 40g of the uncured emulsion and add 30g of quartz sand (40-70 mesh), 30g of quartz sand (80-120 mesh), and 15g of cement in sequence. Stir well to obtain epoxy mortar. Let it stand for 4 hours to cure and obtain a mid-coat coating containing flexible segment epoxy resin with a density of 0.242g / cm³. 3 .

[0052] Example 2

[0053] Weigh 29.2g of triethylenetetramine and 8.4g of dimer acid and mix them evenly in a three-necked flask. Stir at 145℃ for 4 hours, then cool to 75℃. Add 36.6g of diethylene glycol dibutyl ether solution of E51 type epoxy resin at a dropping rate of 0.5ml per minute. Stir for 3 hours, then add 20g of terminal olefin polyether 91-B and keep warm for 2.5 hours. Finally, add 84.72g of deionized water to disperse and obtain a reddish-brown transparent viscous dimer acid modified epoxy resin curing agent DTEB.

[0054] Weigh 15g of curing agent DTEB, add 15g of deionized water for dilution, slowly pour in 10g of E51 type epoxy resin and stir to emulsify, then add 10g of deionized water for dilution. After the emulsion is evenly dispersed and there are no oil droplets, take a portion of the epoxy resin emulsion and let it stand at room temperature to cure to obtain epoxy resin E51-DTEB containing flexible chain segments.

[0055] Take 40g of the uncured emulsion and add 30g of quartz sand (40-70 mesh), 30g of quartz sand (80-120 mesh), and 15g of cement in sequence. Stir well to obtain epoxy mortar. Let it stand for 4 hours to cure and obtain a mid-coat coating containing flexible segment epoxy resin with a density of 0.238g / cm³. 3 .

[0056] Example 3

[0057] Weigh 29.2g of triethylenetetramine and 11.2g of dimer acid and mix them evenly in a three-necked flask. Stir at 145℃ for 4 hours, then cool to 75℃. Add 36.6g of diethylene glycol dibutyl ether solution of E51 type epoxy resin at a dropping rate of 0.5ml per minute. Stir for 3 hours, then add 20g of terminal olefin polyether 91-B and keep warm for 2.5 hours. Finally, add 84.72g of deionized water to disperse and obtain a reddish-brown transparent viscous dimer acid modified epoxy resin curing agent DTEB.

[0058] Weigh 15g of curing agent DTEB, add 15g of deionized water for dilution, slowly pour in 10g of E51 type epoxy resin and stir to emulsify, then add 10g of deionized water for dilution. After the emulsion is evenly dispersed and there are no oil droplets, take a portion of the epoxy resin emulsion and let it stand at room temperature to cure to obtain epoxy resin E51-DTEB containing flexible chain segments.

[0059] Take 40g of the uncured emulsion and add 30g of quartz sand (40-70 mesh), 30g of quartz sand (80-120 mesh), and 15g of cement in sequence. Stir well to obtain epoxy mortar. Let it stand for 4 hours to cure and obtain a mid-coat coating containing flexible segment epoxy resin with a density of 0.240g / cm³. 3 .

[0060] Example 4

[0061] Weigh 29.2g of triethylenetetramine and 14.0g of dimer acid and mix them evenly in a three-necked flask. Stir at 145℃ for 4 hours, then cool to 75℃. Add 36.6g of diethylene glycol dibutyl ether solution of E51 type epoxy resin at a dropping rate of 0.5ml per minute. Stir for 3 hours, then add 20g of terminal olefin polyether 91-B and keep warm for 2.5 hours. Finally, add 84.72g of deionized water to disperse and obtain a reddish-brown transparent viscous dimer acid modified epoxy resin curing agent DTEB.

[0062] Weigh 15g of curing agent DTEB, add 15g of deionized water for dilution, slowly pour in 10g of E51 type epoxy resin and stir to emulsify, then add 10g of deionized water for dilution. After the emulsion is evenly dispersed and there are no oil droplets, take a portion of the epoxy resin emulsion and let it stand at room temperature to cure to obtain epoxy resin E51-DTEB containing flexible chain segments.

[0063] Take 40g of the uncured emulsion and add 30g of quartz sand (40-70 mesh), 30g of quartz sand (80-120 mesh), and 15g of cement in sequence. Stir well to obtain epoxy mortar. Let it stand for 4 hours to cure and obtain a mid-coat coating containing flexible segment epoxy resin with a density of 0.241g / cm³. 3 .

[0064] Infrared testing

[0065] Infrared testing (FI-TR) Figure 1 It can be seen that the curing agent DTEB modified with dimer acid has high curing properties at 2910 and 3620 cm⁻¹. –1The peaks at 1650 cm⁻¹ represent strong peaks for the stretching vibrations of saturated C-H bonds and broad peaks for the stretching vibrations of O-H and N-H bonds, respectively. This is because the numerous saturated C-H bonds and carbonyl groups in the dimer acid (DA) structure associate with intermolecular hydrogen bonds, resulting in strong absorption. This indicates that the dimer acid was successfully grafted onto triethylenetetramine. After the dimer acid reacts with triethylenetetramine, an amide bond is formed, with its corresponding absorption peak at 1650 cm⁻¹. –1 It also exhibits strong absorption, a characteristic also seen in DTEB. At 1508 and 1250 cm⁻¹ –1 The absorption peaks at 830 cm⁻¹ represent the stretching vibration peaks of the C==C bond and the symmetric and antisymmetric stretching vibration peaks of the C—O—C bond. This absorption originates from the terminal carboxyl polyether 91-B. –1 The peak at this point represents the out-of-plane bending vibration of the C-H bond on the benzene ring, and this absorption originates from the epoxy resin monomer E-51. This confirms that the curing agent DTEB was successfully synthesized.

[0066] Molecular weight test

[0067] Table 1. Relative molecular mass of the dimer acid modified curing agents in Examples 1-4

[0068]

[0069] Each curing agent corresponds to two molecular chains, denoted as molecular chain A and molecular chain B, and their synthesis pathways are as follows:

[0070]

[0071]

[0072] Relative molecular mass is often used to confirm the successful preparation of small molecule polymers or to judge the performance of macromolecular polymers as a function of relative molecular mass. Polydispersity index is often used to judge whether the molecular weight distribution of a polymer is uniform. With the increase of dimer acid content, the relative molecular mass of DTEB changes little and is bimodal. The number-average relative molecular weight distribution is concentrated in 3358-3551 and 1493-1621, respectively, as shown above. Among them, 3358-3551 can be identified as B molecular chain, which is the main product in the curing agent DTEB, while 1493-1621 can be identified as A molecular chain, which is the minor product in the curing agent DTEB. This is because the reaction rate between dimer acid and triethylenetetramine is too fast. During the polymerization process, multiple dimer acid monomers react with one triethylenetetramine simultaneously, resulting in the final curing agent containing both dimer acid-containing and non-dimer acid molecular chains. As shown in the formula below, during the curing of E51 type epoxy resin by curing agent DTEB, the active sites of the amine groups in molecular chain A and molecular chain B simultaneously react with the epoxy groups in the epoxy resin for curing. Furthermore, as the dimer acid content increases, the polydispersity index of DTEB remains between 1.11 and 1.19, indicating a concentrated and uniform molecular weight distribution. This is because the overall molecular weight of the synthesized curing agent is relatively small, and there is no chain transfer or chain termination during the synthesis process, resulting in fewer byproducts.

[0073]

[0074] Thermal performance analysis

[0075] The thermal stability of polymers is related to their molecular structure, chain regularity, intermolecular forces, and the heat resistance of their functional groups. Polymer stability refers to the performance of polymers under specific conditions, including heat resistance, light resistance, oxidation resistance, water resistance, microbial resistance, and solvent resistance. High temperatures can lead to the breaking of chemical bonds, chain breakage, or changes in molecular structure within polymer molecules; light exposure can cause polymer degradation and aging. The configuration and arrangement of polymer chains affect their stability: polymers with higher crosslinking degrees are more stable than linear polymers. Highly stretched polymer chains are more prone to breakage or chemical reactions than bent or cyclic chains. Closely packed chain structures are generally more stable than loosely packed structures. Longer molecular weight polymer chains can provide more stabilizing sites, reducing the possibility of intermolecular movement and reactions.

[0076] Depend on Figure 2a as well as Figure 2b It can be seen that the temperature at which E51-DTEB loses 5% of its mass is 345℃, the residual mass at 700℃ is 6.7%, and the glass transition temperature T0 is [missing information]. gThe temperature was 124℃, indicating that the prepared flexible segment epoxy resin E51-DTEB is a polymer material with good thermal stability, exhibiting a glassy state at room temperature. This is because the high-energy carbon-oxygen double bonds in the dimer acid improve the thermal stability of E51-DTEB, the dendritic long carbon chain structure endows E51-DTEB with a certain degree of branching, increasing its residual char content, and the polar amide bonds lead to a decrease in the mobility of E51-DTEB molecular chain segments. g Increase.

[0077] Viscosity analysis

[0078] This invention uses H225 epoxy resin curing agent purchased from the market to replace DTEB, and uses the same preparation method as this invention to prepare ordinary epoxy mortar (equivalent to the epoxy mortar of this invention) and ordinary epoxy resin intermediate coating for comparison with this invention.

[0079] Depend on Figure 3 It can be seen that the viscosity of both ordinary epoxy mortar and epoxy mortar containing flexible segments decreases with increasing shear rate, and the viscosity of epoxy mortar containing flexible segments is consistently slightly higher than that of ordinary epoxy mortar. This is because the curing of epoxy mortar depends on the reaction between the curing agent and epoxy resin in the epoxy emulsion. Only a very small portion of the mortar cures in a short time, and the few chemical bonds formed by the curing process do not have a significant impact on the viscosity. Therefore, both types of epoxy mortar exhibit a decrease in viscosity with increasing shear rate, i.e., shear thinning. However, the epoxy mortar containing flexible segments, due to the introduction of dimer acid, a large molecule with a branched long carbon chain, into the epoxy emulsion, creates an entangled structure between the molecular chains during curing. This entangled structure, while not as strong as chemical bonds, still contributes to an overall increase in the viscosity of the epoxy mortar. Therefore, it can be concluded that the viscosity change of the self-made epoxy mortar containing flexible segments according to this invention meets the requirements for on-site construction.

[0080] Mechanical property analysis

[0081] The epoxy resin emulsion prepared according to the above method is mixed with aggregates (cement and quartz sand) to obtain epoxy mortar. The curing process is as follows: Figure 4As shown, the curing of epoxy mortar can be divided into four processes: When the epoxy resin emulsion and aggregate are first mixed, the polymer particles formed by the combination of epoxy monomers and curing agent, cement particles, aggregate clumps, and trapped air are free in the aqueous solution. After initial stirring (step one), the hydrophobic groups present in the polymer particles will encapsulate the cement, aggregate, and trapped air. The product of the polymer particles combining with cement and aggregate is cement gel. After re-stirring (step two), the free cement, cement gel, and trapped air will combine under the action of the polymer, and the granular substances will form large clumps. Finally (step three), after curing, the free cement, cement gel, and trapped air are all combined, and the polymer particles between the large clumps also combine and solidify. In this process, if the reaction between the epoxy monomer and the curing agent is too fast, it will lead to uneven dispersion of the polymer in the aggregate, and the polymer will not be able to effectively encapsulate the aggregate and provide sufficient mechanical properties.

[0082] Depend on Figure 5 As shown in Table 2, the compressive strength of ordinary epoxy resin intermediate coating is 5.32 MPa, and the compression ratio at break is 14.98%. In contrast, the compressive strength of the epoxy resin intermediate coating containing flexible segments is 2.92 MPa, a decrease of 2.4 MPa, while the compression ratio at break is 27.35%, an increase of 12.37%. Compared to ordinary epoxy resin intermediate coating, the epoxy resin intermediate coating containing flexible segments loses some compressive strength, but the compression ratio at break is significantly improved. This is due to the introduction of dimer acid into the epoxy resin. After the long carbon chain structure of the macromolecule, the compatibility between the alkyl segments of the macromolecule and the aggregate is not ideal. After the epoxy mortar is cured, the dimer acid forms stress concentration points inside it. Therefore, the compressive strength of the epoxy resin intermediate coating containing flexible segments is reduced. However, as a long carbon chain with good flexibility, the dimer acid allows the epoxy resin in the epoxy mortar to still have a certain mobility after curing. This mobility can evenly disperse the pressure along the molecular chain, resulting in a significant improvement in the compressive strength at break of the epoxy resin intermediate coating containing flexible segments.

[0083] Depend on Figure 6a , Figure 6bAs shown in Table 3, the impact resistance of ordinary epoxy resin intermediate coating is 23.3 cm. Within this range, the coating remains undamaged and without cracks after impact. Outside this range, impacts cause damage to the surrounding coating, with the coating completely detaching at the impact point. In contrast, the impact resistance of epoxy resin intermediate coating containing flexible segments is 35 cm. Within this range, the coating remains undamaged and without cracks after impact. Outside this range, impacts cause damage to the surrounding coating, with some coating remaining at the impact point. This is due to the compliant long carbon chains in the dimer acid. On one hand, the epoxy resin in the epoxy resin intermediate coating containing flexible segments retains some mobility after curing to disperse the impact force, resulting in stronger impact resistance. On the other hand, the long carbon chains have stronger adhesion to the substrate and quartz sand, allowing the coating to be better preserved after impact. Therefore, it can be concluded that the epoxy resin intermediate coating containing flexible segments prepared in this invention has good toughness and impact resistance.

[0084] Table 2 Mechanical property curves of epoxy resin intermediate coatings

[0085]

[0086] Table 3 Test parameters for impact resistance of epoxy resin intermediate coating

[0087]

[0088] Contact angle test

[0089] Table 4 Contact Angle Test Parameters for Epoxy Resin Mid-Coat Coating

[0090]

[0091] Contact angle is commonly used as a standard to evaluate the hydrophobicity (hydrophilicity) level of a solid surface. During the curing process of epoxy mortar, the epoxy resin can fill the gaps between the quartz sand and cement, making the coating structure more complete and dense. The molecular chain structure of the epoxy resin can also affect the hydrophobic and hydrophilic properties of the coating. Figure 7a , Figure 7bAs shown in Table 4 above, the average contact angle of ordinary epoxy resin intermediate coating is 61.3°, while the average contact angle of epoxy resin intermediate coating containing flexible segments is 77.3°. Both coatings have contact angles less than 90°, indicating good hydrophilicity. However, the contact angle of epoxy resin intermediate coating containing flexible segments is slightly higher than that of ordinary epoxy resin intermediate coating, indicating better hydrophobicity. This is because introducing a long carbon chain structure of dimer acid, a macromolecule, into the epoxy resin enhances the hydrophobicity of the coating. On the one hand, the alkyl segment, being a highly hydrophobic segment, plays a major role in encapsulating the aggregate. The hydrophilic groups, such as amino groups, alkoxy groups, and amide bonds, constitute a relatively small proportion of the epoxy resin molecular chain. The formation of a coating between the epoxy resin containing flexible segments and the aggregate enhances the hydrophobicity of the coating. On the other hand, dimer acid is a long carbon chain macromolecule with a branched structure. During curing, the branched structure causes entanglement between the molecular chains, resulting in a denser coating structure and enhanced hydrophobicity. Therefore, it can be determined that the epoxy resin intermediate coating containing flexible segments prepared in this invention has a certain hydrophobicity.

Claims

1. A method for preparing an epoxy resin intermediate coating containing flexible segments, characterized in that, Includes the following steps: Step 1: Mix triethylenetetramine and dimer acid at a mass ratio of 1:(0.3-0.6) until homogeneous. Then, stir and react at 140-145 °C for 3.5-4.5 h. Afterward, cool to 70-80 °C and add a diethylene glycol dibutyl ether solution of epoxy resin dropwise to the resulting reaction solution and stir for 2.5-3.5 h. Then, add terminal olefin polyether. The mass ratio of epoxy resin, diethylene glycol dibutyl ether, and triethylenetetramine is 1.1:0.1:1, the dropping rate is 0.4-0.6 ml / min, and the mass ratio of terminal olefin polyether to triethylenetetramine is 6.8:

1. Keep warm for 2-3 h, and finally disperse evenly with deionized water. The mass ratio of deionized water to triethylenetetramine is 2.9:1 to obtain dimer acid modified epoxy resin curing agent. Step 2: Dilute the dimer acid modified epoxy resin curing agent with deionized water at a mass ratio of 1:1 to obtain a dispersion. Then, add epoxy resin for emulsification at a mass ratio of 1:3 to the dimer acid modified epoxy resin curing agent. Add deionized water to dilute the mixture, with the deionized water accounting for 25% of the total mass of the dispersion and epoxy resin. Once the resulting emulsion is evenly dispersed, an epoxy resin emulsion is obtained. Step 3: Mix epoxy resin emulsion, quartz sand, and cement evenly. The quartz sand is divided into 40-70 mesh quartz sand and 80-120 mesh quartz sand. The mass ratio of 40-70 mesh quartz sand, 80-120 mesh quartz sand, cement, and dimer acid modified epoxy resin curing agent from Step 2 is 3:3:2:6 to obtain epoxy mortar. Let the epoxy mortar stand for 3.5-4.5 hours to obtain a mid-coat coating containing flexible segment epoxy resin. The epoxy resin mentioned in steps 1 and 2 is type E51 epoxy resin, and the terminal olefin polyether mentioned in step 1 is type 91-B.

2. An epoxy resin intermediate coating containing flexible segments obtained by the preparation method of the epoxy resin intermediate coating containing flexible segments as described in claim 1.

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