An epoxy resin mortar and a method for preparing the same

Abstract

This invention belongs to the field of building materials technology, specifically relating to an epoxy resin mortar and its preparation method. The epoxy resin mortar comprises components A, B, and C in a mass ratio of 1:(0.2-0.8):(3-8). Component A includes epoxy resin, phenyl glycidyl ether, defoamer, and coupling agent; component B includes amino-terminated epoxy resin prepolymer and accelerator; and component C includes graded sand and spherical expandable graphite. The initial expansion temperature of the spherical expandable graphite is ≤80℃, and its particle size ranges from 10 to 50 micrometers. This epoxy resin mortar has advantages such as low shrinkage, large single-layer application thickness, high strength, and high adhesion, making it particularly suitable for repair and reinforcement, grouting and filling, and paving protection applications where high shrinkage rates are required.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to an epoxy resin mortar and its preparation method. Background Technology

[0002] Epoxy resin mortar is a high-strength, erosion-resistant, wear-resistant, and highly adhesive solid sealing material. It is widely used for the repair of damaged flow surfaces in hydraulic structures, the reinforcement of concrete structures, and the sealing and repair of surface defects such as honeycomb, pitting, and exposed reinforcement.

[0003] The shrinkage of epoxy resin during the curing process is between 2% and 5%, making the finished product highly susceptible to deformation, warping, and even cracking. There are two main reasons for this shrinkage: ① The intermolecular van der Waals forces in the liquid state transform into covalent bonds in the cross-linked structure, and these covalent bonds have shorter bond lengths; ② The reaction process releases a large amount of heat, which is lost naturally leading to shrinkage.

[0004] To reduce the shrinkage of epoxy resin, patent CN105440584A discloses a low-shrinkage epoxy resin system and its preparation method. This method achieves a 50% reduction in epoxy resin shrinkage by introducing nano-barium titanate into the system and employing coupling agents and ultrasonic treatment. However, this method involves a complex preparation process, requires high-temperature curing, and uses expensive nanomaterials. Patent CN103554842A discloses an epoxy grouting material that reduces epoxy resin shrinkage by synthesizing a low-viscosity epoxy resin and combining it with a modified curing agent, an active rubber toughening agent, and a bicyclic lactone expanding monomer. However, this approach involves a complex epoxy resin synthesis process, expensive toughening agents, and the bicyclic lactone expanding monomer is not only expensive but also exhibits insufficient ring-opening reaction with the curing agent molecules, limiting its effectiveness.

[0005] Increasing the thickness of a single application and reducing the curing shrinkage rate have always been important directions for the development of high-strength epoxy resin mortar. Summary of the Invention

[0006] The purpose of this invention is to provide an epoxy resin mortar with large single-application thickness, low shrinkage, and low cost, as well as its preparation method.

[0007] Specifically, the present invention provides the following technical solutions:

[0008] An epoxy resin mortar comprises component A, component B, and component C in a mass ratio of 1:(0.2-0.8):(3-8), wherein component A comprises epoxy resin, phenyl glycidyl ether (reactive diluent), defoamer, and coupling agent; component B comprises amino-terminated epoxy resin prepolymer (curing agent) and accelerator; and component C comprises graded sand and spherical expandable graphite.

[0009] The initial expansion temperature of the spherical expandable graphite is ≤80℃, and the particle size range is 10-50 micrometers.

[0010] Preferably, by weight, component A comprises 70-95 parts of epoxy resin, 3-28 parts of phenyl glycidyl ether, 1-3 parts of defoamer, and 1-5 parts of coupling agent.

[0011] Component B comprises 85-100 parts of amino-terminated epoxy resin prepolymer and 1-10 parts of accelerator.

[0012] The C component comprises 95-99.5 parts of graded sand and 0.5-5 parts of spherical expandable graphite;

[0013] More preferably, component B further includes 0-10 parts by weight of a latent curing agent; more preferably, the latent curing agent is bis-N,N'-(methyl-butylmethylene)-diethylenetriamine, which is a ketimine. This component can react with water in a humid environment to generate polyamines, which participate in the curing process of epoxy resin, thereby improving the curing efficiency of epoxy in a humid environment and increasing the bonding strength of the humid substrate.

[0014] Preferably, the epoxy resin is a bisphenol A type epoxy resin and / or a bisphenol F type epoxy resin; more preferably, the epoxy resin is a mixture of 50-70 wt% bisphenol A type epoxy resin and 30-50 wt% bisphenol F type epoxy resin. Using the above epoxy resin mixture can effectively avoid the crystallization problem that occurs when the epoxy resin is applied at lower temperatures.

[0015] Preferably, the defoamer is a polysiloxane-based defoamer.

[0016] Preferably, the coupling agent is a terminal epoxy silane coupling agent; more preferably, it is γ-glycidoxypropyltrimethoxysilane.

[0017] Preferably, the terminal amino epoxy resin prepolymer is a terminal amino prepolymer formed by reacting epoxy resin with an excess of small molecule primary amine; more preferably, the small molecule primary amine is one or more of ethylenediamine, diethylenetriamine, 1,3-cyclohexanedimethylamine, isophoronediamine, and polyetheramine D230.

[0018] Preferably, the accelerator is one or more of 2,4,6-tris(dimethylaminomethyl)phenol, benzyl dimethylamine, o-hydroxybenzyl dimethylamine, and N,N-dimethylaniline.

[0019] The present invention also provides a method for preparing the above-mentioned epoxy resin mortar, comprising the following steps:

[0020] S1. Mix epoxy resin, phenyl glycidyl ether, defoamer, and coupling agent evenly to obtain component A;

[0021] S2. Add accelerator and bis-N,N'-(methyl-butylmethylene)-diethylenetriamine to the amino-terminated epoxy resin prepolymer and mix evenly to obtain component B;

[0022] S3. Mix the graded sand and spherical expandable graphite evenly to obtain component C;

[0023] S4. Mix components A and B evenly, then add component C and mix evenly to obtain epoxy resin mortar.

[0024] The beneficial effects achieved by this invention are as follows:

[0025] 1) The epoxy resin mortar provided by the present invention adds low-temperature spherical expandable graphite to component C, which can improve the thermal conductivity of the mortar without affecting its fluidity, which is conducive to the dissipation of reaction heat during the curing process, and the mortar can be applied to a thicker single layer.

[0026] 2) The epoxy resin mortar provided by this invention, during a single, high-thickness construction process (when the internal temperature exceeds the initial expansion temperature of expandable graphite), the micro-expansion effect of spherical expandable graphite can effectively compensate for shrinkage during the plastic stage of epoxy resin, with a comprehensive shrinkage rate ≤2%; this invention limits the particle size range of spherical expandable graphite to 10-50 micrometers. Studies have found that spherical expandable graphite with too small a particle size easily deteriorates the mortar's fluidity, and at the same time, the expansion ratio is limited, which is not conducive to compensating for shrinkage;

[0027] 3) The epoxy resin mortar provided by the present invention uses phenyl glycidyl ether containing rigid benzene rings as an active diluent and amino-terminated epoxy resin prepolymer as a curing agent, which further reduces the reaction heat during the crosslinking process of the system, reduces the intrinsic shrinkage of the matrix, and increases the number of single constructions.

[0028] 4) The epoxy resin mortar provided by the present invention preferably uses a mixture of 50-70 wt% bisphenol A type epoxy resin and 30-50 wt% bisphenol F type epoxy resin, which can effectively avoid the crystallization problem of epoxy resin when applied at lower temperatures. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art, or in accordance with the product manual.

[0030] In the following examples, the mechanical properties and 48-hour curing shrinkage rate of epoxy resin mortar were tested according to the relevant provisions of DL / T 5193 "Technical Specification for Epoxy Resin Mortar" and JTG 3420-2020 "Test Procedures for Cement and Cement Concrete in Highway Engineering"; the curing reaction heat test method was as follows: a 100×100×100mm sample was formed, and the highest temperature T at the center of the sample during the curing process was monitored. max The sample molding and curing temperature was 23±2℃, and the relative humidity was 50±5%.

[0031] Bisphenol A type epoxy resin uses Nan Ya NPEL-127E, bisphenol F type epoxy resin uses NPEF-170; silane coupling agent uses KH-560; defoamer uses polysiloxane defoamer BYK-A530.

[0032] The accelerator used is 2,4,6-tris(dimethylaminomethyl)phenol;

[0033] The specific preparation method of the amine-terminated epoxy resin prepolymer is as follows: In the example, the preparation method of the amine-terminated epoxy resin prepolymer is as follows: small molecule primary amines (ethylenediamine, 1,3-cyclohexanedimethylamine, isophoronediamine, and polyetheramine, respectively) are dissolved in toluene at a concentration of 1 mol / L; epoxy resin is slowly added at 25°C and under mechanical stirring at 200±20 r / min, with the molar ratio of epoxy resin to small molecule primary amines being 1:1.5, 1:1.8, 1:2, and 1:2, respectively; after reacting for 2 hours, the mixture is cooled to room temperature, and the solvent is removed by vacuum distillation to obtain the amine-terminated epoxy resin prepolymer.

[0034] The graded aggregate is a mixture of quartz sand with different particle sizes, and the proportions of each component are 10% for 10-50 mesh, 35% for 40-80 mesh, 40% for 200 mesh, and 15% for fly ash.

[0035] Spherical expandable graphite is obtained by crushing, sieving and classifying expandable graphite with an initial expansion temperature of 76℃, and the particle size range is 10-50 micrometers.

[0036] The preparation methods for each embodiment are as follows:

[0037] Epoxy resin, diluent, defoamer, and silane coupling agent are added to the mixing tank in sequence according to the proportion. After mixing evenly, component A is obtained.

[0038] An accelerator and bis-N,N'-(methyl-butylmethylene)-diethylenetriamine were added sequentially to the amino-terminated epoxy resin prepolymer and stirred until homogeneous to obtain component B.

[0039] Graded aggregates and spherical expandable graphite are added to a mixing container and mixed evenly to obtain component C.

[0040] Mix components A and B thoroughly, then add component C and mix thoroughly to obtain the final product.

[0041] After casting, the 28-day compressive strength, curing shrinkage rate, and T were tested on the samples. max .

[0042] The formulation ratios and performance data of each embodiment and comparative example are shown in Table 1. Comparative Example 1 did not add spherical expandable graphite compared to Example 1; Component B of Comparative Example 2 used the commercially available phenolic amine curing agent T31. The results show that the epoxy resin mortar of the present invention has advantages such as low shrinkage (<2%), low heat release, high strength (over 115 MPa), and high adhesion. The inventors believe that the low shrinkage rate is mainly due to two factors: first, the low-temperature spherical expandable graphite effectively compensates for early plastic shrinkage when the internal temperature of the mortar exceeds the initial expansion temperature; second, the use of phenyl glycidyl ether containing a rigid benzene ring as an active diluent and the terminal amino epoxy resin prepolymer as a curing agent further reduces the heat of reaction during the crosslinking process and decreases the intrinsic shrinkage of the matrix. The synergistic effect of these two factors reduces the shrinkage rate of the mortar. Under the same size, the maximum internal temperature of epoxy resin mortar is significantly lower than that of existing technologies. This is mainly due to the use of terminal amine prepolymers, which reduces the heat of polymerization, and the addition of spherical expandable graphite, which improves the thermal conductivity of the matrix and facilitates rapid heat dissipation. As a result, the thickness of the mortar can be applied in a single application is greater.

[0043] Table 1

[0044]

[0045]

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An epoxy resin mortar, characterized by It includes components A, B, and C with a mass ratio of 1:(0.2-0.8):(3-8), wherein, Component A comprises 70-95 parts epoxy resin, 3-28 parts phenyl glycidyl ether, 1-3 parts defoamer, and 1-5 parts coupling agent; the epoxy resin is a mixture of 50-70 wt% bisphenol A type epoxy resin and 30-50 wt% bisphenol F type epoxy resin. Component B comprises 85-100 parts of amino-terminated epoxy resin prepolymer and 1-10 parts of accelerator. The C component comprises 95-99.5 parts of graded sand and 0.5-5 parts of spherical expandable graphite; The initial expansion temperature of the spherical expandable graphite is ≤80℃, and the particle size range is 10-50 micrometers.

2. The epoxy resin mortar according to claim 1, characterized in that Component B also includes 0-10 parts by weight of a latent curing agent.

3. The epoxy resin mortar according to claim 2, characterized in that, The latent curing agent is bis-N,N'-(methyl-butylmethylene)-diethylenetriamine.

4. The epoxy resin mortar according to any one of claims 1-3, characterized in that, The defoamer is a polysiloxane-based defoamer.

5. The epoxy resin mortar according to any one of claims 1-3, characterized in that, The coupling agent is a terminal epoxy silane coupling agent.

6. The epoxy resin mortar according to claim 5, characterized in that, The coupling agent is γ-glycidoxypropyltrimethoxysilane.

7. The epoxy resin mortar according to any one of claims 1-3, characterized in that, The terminal amino epoxy resin prepolymer is a terminal amino prepolymer formed by reacting epoxy resin with an excess of small molecule primary amine.

8. The epoxy resin mortar according to claim 7, characterized in that, The small molecule primary amine is one or more of ethylenediamine, diethylenetriamine, 1,3-cyclohexanedimethylamine, isophoronediamine, and polyetheramine D230.

9. The epoxy resin mortar according to any one of claims 1-3, characterized in that, The accelerator is one or more of 2,4,6-tris(dimethylaminomethyl)phenol, benzyl dimethylamine, o-hydroxybenzyl dimethylamine, and N,N-dimethylaniline.

10. The method for preparing epoxy resin mortar according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Mix epoxy resin, phenyl glycidyl ether, defoamer, and coupling agent evenly to obtain component A; S2. Add accelerator and bis-N,N'-(methyl-butylmethylene)-diethylenetriamine to the amino-terminated epoxy resin prepolymer and mix evenly to obtain component B; S3. Mix the graded sand and spherical expandable graphite evenly to obtain component C; S4. Mix components A and B evenly, then add component C and mix evenly to obtain epoxy resin mortar.

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