Latent curing agent of core-shell structure and method for manufacturing the same

Abstract

The present disclosure relates to a core-shell structured latent curing agent, a method for manufacturing the same, and a one-component epoxy resin containing the same. Specifically, the core-shell structured latent curing agent according to the present disclosure uses a solid amine-based adduct as the core and a PEO-based polymer as the shell, so that a denser and more stable film is formed on the surface of the curing agent, which can greatly improve the latent properties of the curing agent and provide excellent storage stability.

Description

Technology Field

[0001] The present disclosure relates to a core-shell structured latent curing agent, a method for manufacturing the same, and a one-component epoxy resin containing the same. Background Technology

[0002] Epoxy resins are widely used in various applications, such as paints, electrical and electronic insulating materials, and adhesives, because their cured products exhibit excellent mechanical, electrical, thermal, chemical resistance, and adhesion properties.

[0003] Generally, epoxy resin compositions are classified into two-component or one-component types depending on their storage form. Two-component epoxy resin compositions are used by mixing appropriate amounts of epoxy resin and hardener immediately before use, whereas one-component epoxy resin compositions are stored with the epoxy resin and hardener already mixed, allowing for immediate use without additional processing.

[0004] In addition, the above-mentioned two-component epoxy resin composition is difficult to store or handle, carries the possibility of measurement errors, and causes reduced work efficiency; therefore, a one-component epoxy resin composition in which the epoxy resin and curing agent are mixed in advance is generally preferred.

[0005] Therefore, latent curing agents that do not undergo a curing reaction at room temperature and induce a curing reaction only when a certain stimulus, such as heat, is essential; to this end, the method of encapsulating the curing agent is widely used. Encapsulated latent curing agents do not affect the curing characteristics of the curing agent due to the protective film, and can be expected to enhance the storage stability of the solution. Prior art literature

[0006] Republic of Korea Registered Patent Publication No. 10-1809935 The problem to be solved

[0007] The present disclosure aims to provide a latent curing agent and a method for manufacturing the same, which can be manufactured in an environmentally friendly process by utilizing a spray drying technique using water as a solvent and forms a dense and stable film on the surface of the curing agent to ensure excellent storage stability. means of solving the problem

[0008] To achieve the above objective, one embodiment of the present invention provides a latent curing agent having a core-shell structure, comprising: an amine-based adduct as a core material; and a shell comprising a water-soluble polymer surrounding the core material, wherein a core-shell structure is formed by spray drying.

[0009] Another embodiment of the present invention provides a one-component epoxy resin comprising: an epoxy resin; and a latent curing agent having a core-shell structure dispersed within the epoxy resin.

[0010] Another embodiment of the present invention provides a method for manufacturing a core-shell structured latent curing agent, comprising the steps of: dispersing an amine-based adduct in an aqueous solution of a water-soluble polymer to prepare a suspension; and passing the suspension through a spray drying device to manufacture a core-shell structured latent curing agent. Effects of the invention

[0011] The core-shell structured latent curing agent according to the present disclosure uses a solid amine-based adduct as the core and a PEO-based polymer as the shell, so that a denser and more stable film is formed on the surface of the curing agent, which can greatly improve the latent properties of the curing agent and has excellent storage stability.

[0012] In addition, the method for manufacturing a latent curing agent according to the present disclosure is environmentally friendly by utilizing a spray drying technique using water as a solvent. Brief explanation of the drawing

[0013] Figure 1 schematically illustrates the manufacturing process of a core-shell structured latent curing agent according to one embodiment of the present invention. FIG. 2 is a solid amine-based adduct according to one embodiment of the present invention. 1 This shows the H NMR results. Figure 3 shows an optical microscope (OM) image of a solid amine-based adduct according to one embodiment of the present invention. Figures 4a and 4b respectively show scanning electron microscope (SEM) images of Comparative Example 1 and Example 1 according to Test Example 1. Figure 5 shows the results of confirming storage stability according to Test Example 2. Figure 6 shows the results of confirming the curing behavior according to Test Example 3. Specific details for implementing the invention

[0014] The present invention will be described in detail below.

[0015] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0016] In this specification, “potential curing agent” means that it does not act as a curing agent when not under specific curing conditions.

[0017] In one aspect, the present invention may relate to a core-shell structured potential curing agent.

[0018] In one embodiment, the potential curing agent of the core-shell structure may comprise an amine-based adduct as a core material; and a shell comprising a water-soluble polymer surrounding the core material.

[0019] In one embodiment, the core-shell structured potential curing agent can form a core-shell structure by spray drying.

[0020] In one embodiment, the amine-based adduct may be a solid amine-based adduct represented by the following chemical formula 1.

[0021] [Chemical Formula 1]

[0022]

[0023] In one embodiment, the water-soluble polymer may be polyethylene oxide (PEO).

[0024] In one embodiment, the weight average molecular weight of the polyethylene oxide may be 500 to 2,000,000 Da. Specifically, the weight-average molecular weight of the PEO may be 500 Da or more, 700 Da or more, 1,000 Da or more, 3,000 Da or more, 5,000 Da or more, 10,000 Da or more, 50,000 Da or more, 100,000 Da or more, 300,000 Da or more, 500,000 Da or more, 700,000 Da or more, 1,000,000 Da or more, 1,500,000 Da or more, or 1,700,000 Da or more; additionally, the weight-average molecular weight of the PEO may be 2,000,000 Da or less, 1,700,000 Da or less, 1,500,000 Da or less, 1,000,000 Da or less, 900,000 Da or less, 600,000 Da or less, It may be 400,000 Da or less, 100,000 Da or less, 70,000 Da or less, 30,000 Da or less, 10,000 Da or less, 5,000 Da or less, 3,000 Da or less, 1,000 Da or less, or 700 Da or less.

[0025] In one embodiment, the solvent of the spray drying may be water.

[0026] Conventional encapsulated latent curing agents were generally manufactured using a large amount of organic solvent; however, while this method could form a protective film on the surface of the curing agent, it had the problems of being unenvironmentally friendly and having poor storage safety. Specifically, the latent curing agent may react with the organic solvent, which can cause the latent curing agent to be denatured.

[0027] In contrast, a core-shell structured latent curing agent according to one aspect of the present invention can be manufactured in an environmentally friendly manner by using water as a solvent and a solid amine-based adduct as a core, and storage stability can be improved.

[0028] In one embodiment, the weight ratio of the amine-based adduct to the water-soluble polymer may be 1:1 to 19:1. Specifically, the weight ratio of the amine-based adduct to the water-soluble polymer may be 1:1 or more, 2:1 or more, 3:1 or more, 4:1 or more, 5:1 or more, 6:1 or more, 7:1 or more, 8:1 or more, 9:1 or more, 10:1 or more, 11:1 or more, 12:1 or more, 13:1 or more, 14:1 or more, 15:1 or more, 16:1 or more, 17:1 or more, or 18:1 or more, and additionally, the weight ratio of the amine-based adduct to the water-soluble polymer may be 19:1 or less, 18:1 or less, 17:1 or less, 16:1 or less, 15:1 or less, 14:1 or less, 13:1 or less, 12:1 or less, 11:1 or less, 10:1 or less, 9:1 or less, 8:1 or less, 7:1 or less, 6:1 or less, It may be 5:1 or less, 4:1 or less, 3:1 or less, or 2:1 or less.

[0029] In one embodiment, the core-shell structured potential curing agent can be cured at a temperature of 55°C or higher.

[0031] In another aspect, the present invention may relate to a one-component epoxy resin comprising: an epoxy resin; and a latent curing agent of the core-shell structure dispersed within the epoxy resin.

[0033] In another aspect, the present invention may relate to a method for manufacturing a core-shell structured latent curing agent, comprising the steps of: dispersing an amine-based adduct in an aqueous solution of a water-soluble polymer to prepare a suspension; and passing the suspension through a spray drying device to produce a core-shell structured latent curing agent.

[0034] Referring to FIG. 1, a method for manufacturing a latent curing agent with a core-shell structure according to one embodiment of the present invention can finally manufacture a latent curing agent having an adduct core-polymer shell structure by dispersing a solid amine-based adduct in water in which a water-soluble polymer is dissolved, introducing the suspension obtained by dispersing the solid amine-based adduct into a spray dryer, and forming a polymer film on the surface of the adduct through a spraying and heat drying process.

[0035] In one embodiment, the amine-based adduct and water-soluble polymer in the suspension may be 1 to 20 weight percent relative to the total weight of the suspension. Specifically, the amine-based adduct and water-soluble polymer may be 1 wt% or more, 2 wt% or more, 3 wt% or more, 4 wt% or more, 5 wt% or more, 6 wt% or more, 7 wt% or more, 8 wt% or more, 9 wt% or more, 10 wt% or more, 11 wt% or more, 12 wt% or more, 13 wt% or more, 14 wt% or more, 15 wt% or more, 16 wt% or more, 7 wt% or more, 18 wt% or more, or 19 wt% or more based on the total weight of the suspension, and additionally, the amine-based adduct and water-soluble polymer may be 20 wt% or less, 19 wt% or less, 18 wt% or less, 17 wt% or less, 16 wt% or less, 15 wt% or less, 14 wt% or less, 13 wt% or less, 12 wt% or less, 11 wt% or less, 10 wt% or less based on the total weight of the suspension. It may be 9 weight% or less, 8 weight% or less, 7 weight% or less, 6 weight% or less, 5 weight% or less, 4 weight% or less, 3 weight% or less, or 2 weight% or less.

[0036] In one embodiment, the amine-based adduct may be a solid amine-based adduct represented by the following chemical formula 1.

[0037] [Chemical Formula 1]

[0038]

[0039] In one embodiment, the water-soluble polymer may be polyethylene oxide (PEO).

[0040] In one embodiment, the weight average molecular weight of the polyethylene oxide (PEO) may be 500 to 2,000,000 Da. Specifically, the weight-average molecular weight of the PEO may be 500 Da or more, 700 Da or more, 1,000 Da or more, 3,000 Da or more, 5,000 Da or more, 10,000 Da or more, 50,000 Da or more, 100,000 Da or more, 300,000 Da or more, 500,000 Da or more, 700,000 Da or more, 1,000,000 Da or more, 1,500,000 Da or more, or 1,700,000 Da or more; additionally, the weight-average molecular weight of the PEO may be 2,000,000 Da or less, 1,700,000 Da or less, 1,500,000 Da or less, 1,000,000 Da or less, 900,000 Da or less, 600,000 Da or less, It may be 400,000 Da or less, 100,000 Da or less, 70,000 Da or less, 30,000 Da or less, 10,000 Da or less, 5,000 Da or less, 3,000 Da or less, 1,000 Da or less, or 700 Da or less.

[0041] In one embodiment, the weight ratio of the amine-based adduct to the water-soluble polymer may be 1:1 to 19:1. Specifically, the weight ratio of the amine-based adduct to the water-soluble polymer may be 1:1 or more, 2:1 or more, 3:1 or more, 4:1 or more, 5:1 or more, 6:1 or more, 7:1 or more, 8:1 or more, 9:1 or more, 10:1 or more, 11:1 or more, 12:1 or more, 13:1 or more, 14:1 or more, 15:1 or more, 16:1 or more, 17:1 or more, or 18:1 or more, and additionally, the weight ratio of the amine-based adduct to the water-soluble polymer may be 19:1 or less, 18:1 or less, 17:1 or less, 16:1 or less, 15:1 or less, 14:1 or less, 13:1 or less, 12:1 or less, 11:1 or less, 10:1 or less, 9:1 or less, 8:1 or less, 7:1 or less, 6:1 or less, It may be 5:1 or less, 4:1 or less, 3:1 or less, or 2:1 or less.

[0042] As the above-mentioned core-shell structured latent curing agent has been explained in detail above, further explanation is omitted.

[0044] The contents of the present invention will be explained in more detail below through examples and test examples. However, these examples and test examples are provided merely to help understand the contents of the present invention, and the scope of the present invention is not limited to these examples and test examples. Modifications, substitutions, and insertions commonly known in the art may be performed, and such are also included within the scope of the present invention.

[0046] [Preparation Example] Synthesis of Solid Amine-Based Adducts

[0047] A solid amine-based adduct represented by Chemical Formula 1 according to one embodiment of the present invention was synthesized using 2-methylimidazole and isophorone diisocyanate as solutes, dibutyltin dilaurate as a catalyst, and tetrahydrofuran and hexane as solvents.

[0048] A solid amine-based adduct according to one embodiment of the present invention 1 The results of the H NMR verification are shown in Figure 2, and as a result, it was confirmed that the amine-based adduct was successfully synthesized.

[0049] In addition, an optical microscope (OM) image of a solid amine-based adduct according to one embodiment of the present invention is shown in FIG. 3, and as a result, it was confirmed that the solid amine-based adduct according to one embodiment of the present invention has a wide size distribution of 5 μm to 1000 μm.

[0051] [Example 1 and Comparative Example 1] Preparation of Core-Shell Structured Latent Curing Agent

[0052] After placing 980g of distilled water in a container, 4g (Example 1) or 1g (Comparative Example 1) of polyethylene oxide (PEO) was added and dissolved in an ultrasonic water bath for 60 minutes to obtain an aqueous PEO solution. Then, 16g (Example 1) or 19g (Comparative Example 1) of the solid amine-based adduct synthesized in the above preparation example was added and dispersed in an ultrasonic water bath for 60 minutes. Afterward, the obtained dispersion was introduced into a spray dryer (Lab spray dryer KLSD-1500 Korea Medi Co., Ltd., Inlet temp. 120℃, Air blower setting: 15) and subjected to spraying and heat drying processes to produce latent curing agent particles having a core-shell structure.

[0054] [Test Example 1] SEM and EDS Measurement Test of Core-Shell Structured Potential Curing Agent

[0055] Scanning electron microscope (SEM) images of the solid amine-based adduct synthesized in the above preparation example and the core-shell structured latent curing agent of Example 1 were taken using a field emission scanning electron microscope (Nova NanoSEM 450, FEI Company), and the results are shown in Figures 4a and 4b, respectively.

[0056] In the case of the solid amine-based adduct alone, it appears as a white powder-like solid when viewed with the naked eye, but as shown in Fig. 4a, it was confirmed that it has no specific shape when examined with SEM. On the other hand, in the case of the core-shell structured latent curing agent of Example 1, it was confirmed through SEM images, as shown in Fig. 4b, that it was manufactured into round, circular particles.

[0057] In addition, to identify the constituent elements of the surface, energy dispersive spectroscopy (EDS) of the solid amine-based adduct synthesized in the above preparation example and the core-shell structured latent curing agent of Example 1 was measured using an ultra-high resolution scanning electron microscope (Verios 460, FEI Company), and the results are shown in Table 1 below.

[0058] Selected Area 1 Atomic (%) Selected Area 2 Atomic (%) C N O C N O Preparation Example (Solid Amine-based Adduct) 71.47 22.24 6.29 69.09 24.07 6.84 Example 1 (Core-shell structured latent curing agent) 76.54 - 23.46 79.74 - 20.26

[0059] As shown in Table 1 above, in the case of the solid amine-based adduct alone, it was confirmed that nitrogen was detected on the surface of the particle because the nitrogen contained in 2-methylimidazole was measured. On the other hand, in the case of the core-shell structured latent curing agent of Example 1, it was confirmed that no nitrogen was detected, which indicates that the amine-based adduct, which is the core, is not exposed and that a dense and stable film is formed on the surface of the amine-based adduct by a polymer that does not contain nitrogen.

[0061] [Test Example 2] Confirmation of storage stability of core-shell structured latent curing agent

[0062] In order to confirm the storage stability of the solid amine-based adduct (AD) synthesized in the above manufacturing example, the core-shell structured latent curing agent of Example 1 (amine-based adduct core (AD): polymer shell (PEO) = 80:20), and the core-shell structured latent curing agent of Comparative Example 1 (amine-based adduct core (AD): polymer shell (PEO) = 95:5), each was mixed with an epoxy resin (YDF-170, Kukdo Chemical) in a weight ratio of 10:1 (epoxy resin: adduct or core-shell latent curing agent), stored in a chamber at 15°C, and the change in viscosity on a daily basis was measured using a standard digital rotary viscometer WVS-2M (Daehan Science Co., Ltd., RPM: 0.6-30).

[0063] The results are shown in Table 2 and Figure 5 below.

[0064] First Preparation Example (AD) Comparative Example 1 (AD:PEO=95:5) Example 1 (AD:PEO=80:20) 1 28850 7700 8280 2 78200 6620 11060 3 122000 10620 10000 4 144100 3967.5 11500 10 17900 18650 11 21200 15750 14 69950 30867 15 53500 18150 16 72800 22500 17 35366.66667 20900 18 61550 23975 21 166800 52850 22 306400 41200 23 678000 41350 24 73600 25 115100 28 268700

[0065] From the results of Table 2 and Figure 5, it was confirmed that in the case of the solid amine-based adduct of the preparation example alone, curing proceeded completely after 4 days and viscosity could not be measured, and in the case of Comparative Example 1, the low polymer ratio resulted in poor stability of film formation and poor storage stability, whereas in the case of Example 1, a stable film was formed and excellent storage stability was confirmed.

[0067] [Test Example 3] Confirmation of Curing Behavior of Core-Shell Structured Potential Curing Agent

[0068] To confirm the curing behavior of the solid amine-based adduct (AD) synthesized in the above preparation example and the core-shell structured latent curing agent of Example 1 (amine-based adduct core (AD): polymer shell (PEO) = 80:20), each was mixed with an epoxy resin (YDF-170, Kukdo Chemical) at a weight ratio of 10:1 (epoxy resin: adduct or core-shell latent curing agent), and then differential scanning calorimetry (DSC) was performed using a DSC 25 (TA instruments) (measurement range: 30–200°C, 10°C / min, N2 flow). The results are shown in Table 3 and Figure 6 below.

[0069] First peak temperature (°C) Kick-off temperature (°C) Reaction heat (J / g) Preparation Example (AD) 115.81 104.35 497.30 Example 1 (AD:PEO=80:20) 128.78 119.16 314.61

[0070] From the results of Table 3 and Figure 6, it was confirmed that the latent curing agent of Example 1 continued to undergo thermal curing even after the formation of the core-shell structure.

Claims

Claim 1 A latent curing agent having a core-shell structure, comprising: an amine-based adduct as a core material; and a shell comprising a water-soluble polymer surrounding the core material, wherein a core-shell structure is formed by spray drying, and the weight ratio of the amine-based adduct to the water-soluble polymer is 2:1 to 18:

1. Claim 2 In claim 1, the amine-based adduct is a core-shell structured latent curing agent, wherein the amine-based adduct is a solid amine-based adduct represented by the following chemical formula 1: [Chemical Formula 1] . Claim 3 In claim 1, the water-soluble polymer is a core-shell structured latent curing agent, which is polyethylene oxide (PEO). Claim 4 In claim 1, the solvent for the spray drying is water, a core-shell structured latent curing agent. Claim 5 In claim 1, a core-shell structured latent curing agent that cures at a temperature of 55°C or higher. Claim 6 A one-component epoxy resin comprising: an epoxy resin; and a latent curing agent having a core-shell structure according to any one of claims 1 to 5 dispersed within the epoxy resin. Claim 7 A method for manufacturing a core-shell structured latent curing agent according to any one of claims 1 to 5, comprising: a step of preparing a suspension by dispersing an amine-based adduct in an aqueous solution of a water-soluble polymer; and a step of preparing a core-shell structured latent curing agent by passing the suspension through a spray drying device; wherein the weight ratio of the amine-based adduct to the water-soluble polymer is 2:1 to 18:

1. Claim 8 A method according to claim 7, wherein the amine-based adduct and the water-soluble polymer are included in an amount of 1 to 20 weight percent relative to the total weight of the suspension. Claim 9 In claim 7, the method is a solid amine-based adduct represented by the following chemical formula 1, wherein: [Chemical Formula 1] . Claim 10 In claim 7, the water-soluble polymer is polyethylene oxide (PEO), method. Claim 11 delete Claim 12 delete

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