Polymer having an ultraviolet-sensitive self-repairing function and method for producing the same

Abstract

To provide a polymer with a UV-responsive self-healing function and its manufacturing method, where a solid dynamic crosslinked polymer with a UV-responsive self-healing function is capable of being repaired and reprocessed through a dynamic exchange reaction of disulfide induced under exposure to UV radiation at ambient temperature when damaged after curing.SOLUTION: A polymer with a UV-responsive self-healing function is capable of self-healing simply through UV exposure at ambient temperature. Therefore, it can be utilized in the recycling of thermosetting resins that are environmentally challenging to recycle in the plastic industry, and furthermore, serve as an alternative to address various environmental issues.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a polymer having an ultraviolet-sensitive self-healing function at room temperature and a method for producing the same. More specifically, when a solid dynamic crosslinked polymer having an ultraviolet-sensitive self-healing function is damaged after curing, it undergoes a dynamic exchange reaction of disulfide by ultraviolet irradiation at room temperature, enabling repair and reprocessing. The present invention relates to a polymer having an ultraviolet-sensitive self-healing function and a method for producing the same.

Background Art

[0002] As the production volume and usage volume of plastics commonly used in daily life increase year by year, the generation volume of waste plastics is also increasing very rapidly. In the case of landfilling waste plastics, since they do not rot, there is a possibility of causing environmental pollution in the future. In the case of the incineration method, a large amount of harmful substances are released into the atmosphere, contributing to new environmental pollution, and the inflow volume into the coastal areas is also steadily increasing. Thus, the improper disposal of plastics constantly emerges as an environmental problem threatening the ecosystem.

[0003] Currently, the recycling of plastics is known as the most environmentally friendly recycling method with low carbon emissions, in which, after going through stages such as classification and washing processes, it is reused as a recycled raw material by heat treatment (hot processing).

[0004] Among plastic types, in the case of thermosetting resins with excellent chemical resistance, mechanical strength, and structure preservation, they do not melt in heat and cannot be reprocessed, so there are often constraints for material recycling. However, in recent years, a new polymer (CAN: Covalent adaptable network), which is a dynamic crosslinked polymer having the advantages of the above thermosetting resins and at the same time enabling heat treatment (hot processing), has been in the spotlight. Such characteristics are realized by forming a network through dynamic crosslinking between polymer chains.

[0005] However, in the case of conventional CAN, heat is applied to the entire material due to the activation of the exchange reaction at high temperatures, which also leads to an inefficient repair process and excessive energy consumption even in the case of local damage. Furthermore, in the case of polymers used in heat-sensitive products, there are limitations in repairing damage caused by heating.

[0006] Due to such problems, in recent research, studies on polymers that can self-repair at room temperature have been actively conducted. In particular, research on room-temperature self-repair using thermoplastic polyurethane (TPU) has been actively carried out, but due to the thermoplasticity of TPU, its structural stability at high temperatures is impaired, and it has the drawback of being limited for high-temperature applications. Furthermore, thermosetting polymers such as epoxy, which are excellent in properties such as chemical resistance, mechanical strength, and numerical stability, are used in various industries, but in many cases, they often rely on hydrogen bonds and slow exchange reactions, so they require a long time for reprocessing and show a problem of a relatively low physical property recovery rate of about 80%.

[0007] Therefore, in order to overcome the above problems, the present inventors have developed a method for producing a polymer having an ultraviolet-sensitive self-repair function that causes a dynamic exchange reaction of disulfide by ultraviolet irradiation at room temperature, enabling repair and reprocessing, and thus completed the present invention.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention was created to solve the above problems, and the object of the present invention is that when a solid dynamic cross-linked polymer having an ultraviolet-sensitive self-healing function is damaged after curing, a dynamic exchange reaction of disulfide occurs by ultraviolet irradiation at room temperature, enabling repair and reprocessing. The present invention provides a polymer having an ultraviolet-sensitive self-healing function and a method for producing the same, which are characterized in that

[0010] The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those with ordinary knowledge in the technical field to which the present invention belongs from the following description.

Means for Solving the Problems

[0011] The polymer having an ultraviolet-sensitive self-healing function of the present invention for achieving the above object includes a first monomer containing two or more epoxy groups and a second monomer as a curing agent, and is characterized in that the first monomer and the second monomer are combined to cause a dynamic exchange reaction of disulfide, enabling self-healing.

[0012] The first monomer is characterized by including one or more selected from the group consisting of bisphenol-based, aminophenol-based, siloxane-based, and alicyclic epoxy resins.

[0013] The second monomer is a curing agent containing sulfur, and is characterized by including one or more selected from the group consisting of 4-aminophenyl disulfide, 3,3'-dihydroxydiphenyl disulfide, and 4-(2-hydroxyethoxy)phenyl disulfide.

[0014] The second monomer is characterized by being represented by the following Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3.

[0015]

Chem.

[0016] [Chemistry]

[0017] [Chemistry]

[0018] The polymer is characterized in that even if it is damaged after curing, self - repair is enabled by the dynamic exchange reaction of disulfide caused by ultraviolet irradiation.

[0019] The wavelength of the ultraviolet ray is characterized by being 250 - 260 nm.

[0020] The irradiation of the ultraviolet ray is characterized by being carried out at room temperature for 5 - 15 minutes at an intensity of 20 - 40 mW / cm 2 .

[0021] The method for producing a polymer having an ultraviolet - sensitive self - repair function according to the present invention includes a step of mixing and heating a first monomer and a second monomer, a step of putting the heated mixture into a pre - heated mold, a step of subjecting the mixture put into the mold to vacuum replacement to remove bubbles, and a step of obtaining a cured polymer by heating the degassed mixture while raising the temperature.

[0022] The first monomer is a monomer containing two or more epoxy groups and includes one or more selected from the group consisting of bisphenol - based, aminophenol - based, siloxane - based, and alicyclic epoxy resins.

[0023] The second monomer is a curing agent containing sulfur and includes one or more selected from the group consisting of 4 - aminophenyl disulfide, 3,3’ - dihydroxydiphenyl disulfide, and 4 - (2 - hydroxyethoxy)phenyl disulfide.

[0024] The second monomer is characterized by being represented by the following Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3.

[0025]

Chem.

[0026]

Chem.

[0027]

Chem.

[0028] The step of mixing and heating the first monomer and the second monomer is characterized by being performed at 95 to 105 °C for 5 to 15 minutes.

[0029] In the step of subjecting the mixture placed in the mold to vacuum replacement and degassing, it is characterized by performing vacuum replacement and degassing for 10 to 20 minutes.

[0030] In the step of obtaining a cured polymer by heating the degassed mixture while raising the temperature, it is characterized by raising the temperature to 140 to 160 °C and heating for 9 to 11 hours to obtain a cured polymer.

Advantages of the Invention

[0031] When the polymer having an ultraviolet-sensitive self-healing function of the present invention is damaged after curing, a dynamic exchange reaction of disulfide occurs by ultraviolet irradiation at room temperature, enabling repair and reprocessing. Therefore, among plastics, it can be utilized for the recycling of thermosetting resins that are environmentally friendly but difficult to recycle, and can further be utilized as an alternative for dealing with various environmental problems.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0033] Prior to the detailed description of the present invention, the terms used in this specification will be briefly described.

[0034] The terms used in this specification are selected as general terms that are currently widely used as much as possible while considering the functions in the present invention. However, this may change depending on the intentions and precedents of those skilled in the art, the emergence of new technologies, etc. Therefore, the terms used in the present invention are not merely the names of the terms, but are defined based on the meaning of the terms and the overall content of the present invention.

[0035] Throughout the specification, when a part states that a certain component "includes" something, this means, unless otherwise specified, that it does not exclude other components and may further include other components.

[0036] Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention can be realized in various different forms and is not limited to the embodiments described herein.

[0037] Specific matters including the problems to be solved by the present invention, the means for solving the problems, and the effects of the invention are included in the following embodiments and drawings. The advantages, features, and methods for achieving them of the present invention will become clear by referring to the embodiments described in detail hereinafter together with the accompanying drawings.

[0038] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

[0039] The present invention provides a polymer having an ultraviolet-sensitive self-healing function, which includes a first monomer containing two or more epoxy groups and a second monomer as a curing agent, and the first monomer and the second monomer are combined to cause a dynamic exchange reaction of disulfide, enabling self-healing.

[0040] The first monomer may include one or more selected from the group consisting of bisphenol-based, aminophenol-based, siloxane-based, and alicyclic epoxy resins.

[0041] The second monomer is a curing agent containing sulfur and may include one or more selected from the group consisting of 4-aminophenyl disulfide, 3,3'-dihydroxydiphenyl disulfide, and 4-(2-hydroxyethoxy)phenyl disulfide.

[0042] The second monomer may be represented by the following Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3.

[0043]

Chem.

[0044]

Chem.

[0045]

Chem.

[0046] Even if the polymer is damaged after curing, it may be capable of self - repair by the dynamic exchange reaction of disulfide caused by ultraviolet irradiation.

[0047] The wavelength of the ultraviolet light is preferably 250 - 260 nm, and more preferably may be 254 nm.

[0048] The irradiation of the ultraviolet light is preferably carried out at room temperature for 5 - 15 minutes at an intensity of 20 - 40 mW / cm 2 , and more preferably may be carried out at room temperature for 10 minutes at an intensity of 30 mW / cm 2 .

[0049] When the ultraviolet light is irradiated at an intensity of 30 mW / cm 2 for 10 minutes at room temperature, the energy amount may be 18 J / cm 2 .

[0050] The present invention provides a method for producing a polymer having an ultraviolet - sensitive self - repair function, which includes a step of mixing and heating a first monomer and a second monomer, a step of putting the heated mixture into a pre - heated mold, a step of performing vacuum replacement on the mixture put into the mold to remove bubbles, and a step of obtaining a cured polymer by heating the degassed mixture while raising the temperature.

[0051] The first monomer is a monomer containing two or more epoxy groups, and preferably contains one or more selected from the group consisting of bisphenol-based, aminophenol-based, siloxane-based, and alicyclic epoxy resins.

[0052] The second monomer is a curing agent containing sulfur, and preferably contains one or more selected from the group consisting of 4-aminophenyl disulfide, 3,3'-dihydroxydiphenyl disulfide, and 4-(2-hydroxyethoxy)phenyl disulfide.

[0053] The second monomer may be represented by the following Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3.

[0054]

Chem.

[0055]

Chem.

[0056]

Chem.

[0057] The step of mixing and heating the first monomer and the second monomer is preferably carried out at 95 to 105 °C for 5 to 15 minutes, more preferably at 100 °C for 10 minutes.

[0058] In the step of putting the heated mixture into a preheated mold, it is preferable to preheat the mold to 100 °C.

[0059] In the step of subjecting the mixture placed in the mold to vacuum replacement for defoaming, it is preferably subjected to vacuum replacement for defoaming for 10 to 20 minutes, more preferably subjected to vacuum replacement for defoaming for 15 minutes.

[0060] In the step of obtaining the cured polymer by heating the defoamed mixture while raising the temperature, preferably, the temperature is raised to 140 to 160 °C and heated for 9 to 11 hours to obtain the cured polymer. More preferably, the temperature is raised to 150 °C and heated for 10 hours to obtain the cured polymer.

[0061] Hereinafter, in order to facilitate the understanding of the present invention, examples will be given for detailed description. However, the following examples are illustrative of the content of the present invention, and the scope of the present invention is not limited to the following examples. The examples of the present invention are provided to more fully explain the present invention to those having average knowledge in the industry.

[0062] <Example> Synthesis of a Polymer Having an Ultraviolet-Sensitive Self-Healing Function As shown in Figure 1, a liquid epoxy monomer (DGEPEG) and an amine curing agent (2-AFD) with a melting point of 93 °C were stirred at a temperature of 100 °C for 10 minutes to produce a uniform mixture. The mixture was placed in a mold preheated to 100 °C and degassed by vacuum replacement for 15 minutes. After the degassed mixture was heated to 150 °C, it was heated for 10 hours to obtain a network polymer cured by an epoxy-amine addition reaction.

[0063] <Experimental Example 1> Curing of a Polymer Having an Ultraviolet-Sensitive Self-Healing Function Regarding the polymer produced according to the above example, in order to confirm the degree of curing of the polymer over time at 150 °C, gel content analysis was performed and shown in Figure 2. After measuring the weight of each of the polymer samples for different curing times, they were immersed in a tetrahydrofuran (THF) solvent for 1 day. Then, they were further dried in an oven at 60 °C for 1 day, and then the weight was measured again. As a result, it was found that the gel content increased rapidly with the passage of time, reaching a gel content of 90% or more after 8 hours, and this level was maintained thereafter.

[0064] <Experimental Example 2> Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) Analysis The polymer sample cured at 150 °C for 10 hours according to the above example, the epoxy monomer (DGEPEG), and the amine curing agent (2-AFD) were analyzed using ATR-FTIR respectively, and the results are shown in Figure 3. In the cured polymer sample, a broad peak of the hydroxy group due to the hydroxy group formed by the ring-opening reaction of the epoxy functional group appears at a wavenumber near about 3340 cm -1 −1, and it was confirmed that the bending peak of the primary amine (about 1610 cm -1 −1) observed in the amine monomer disappeared in the cured sample, indicating that the reaction of the primary amine was proceeding. Also, since the epoxy peak (about 910 cm -1 −1) appearing in the epoxy monomer disappeared in the cured sample, it was found that the ring-opening reaction of the epoxy ring was proceeding. Therefore, it was confirmed by FT-IR analysis that the curing reaction of epoxy and amine was proceeding completely.

[0065] <Experimental Example 3> Thermomechanical Property Analysis Thermomechanical property analysis was performed on the polymer sample cured at 150 °C for 10 hours according to the above example using a rheometer in temperature sweep mode, and the results are shown in Figure 4. When the temperature was raised from -50 °C, the cured polymer sample showed a glass transition temperature (maximum tan δ) at about -13 °C, and a sharp decrease in the storage modulus was confirmed. Thereafter, in the high temperature range, the storage modulus showed a plateau, indicating that a cross-linked polymer structure exists in the polymer.

[0066] <Experimental Example 4> Stress Relaxation Analysis by UV Irradiation at Room Temperature The polymer produced according to the above example was subjected to stress relaxation analysis at room temperature, and the stress relaxation behaviors with and without ultraviolet (UV) irradiation were compared and shown in Fig. 5. A polymer sample that previously showed very slow stress relaxation at room temperature showed rapid stress relaxation when measured under UV irradiation. From the stress relaxation experiment conducted under the above UV irradiation, an exchange reaction of aromatic disulfide activated by light irradiation was indirectly confirmed.

[0067] <Experimental Example 5> Stress Relaxation Analysis by Temperature Change To examine the influence of temperature on the polymer produced according to the above example, stress relaxation experiments were conducted under UV irradiation at various temperatures such as room temperature, 40 °C, 60 °C, 80 °C, 100 °C, etc., and shown in Fig. 6. As a result, almost the same relaxation behavior was shown regardless of temperature. The results of the stress relaxation behavior during UV irradiation showed almost the same stress relaxation time as the results obtained by conducting a stress relaxation experiment without irradiating UV at a temperature of 100 °C to 120 °C. Therefore, it was confirmed that UV irradiation at room temperature shows the same exchange reaction rate as when heated to a high temperature of 100 to 120 °C without irradiating UV.

[0068] <Experimental Example 6> Repair and Reprocessing by UV Irradiation at Room Temperature A film-like polymer sample produced according to the above example was scratched with a razor blade, a thin quartz plate that allows light transmission was placed above and below the polymer sample, and a slight pressure was applied with a clip. The fixed polymer sample was irradiated with UV light having a wavelength of 254 nm and an intensity of 30 mW / cm 2 for 10 minutes. At this time, the light irradiation energy amount was 18 J / cm 2 . As a result, as shown in Fig. 7, complete recovery of the scratch was observed after UV irradiation at room temperature, but no recovery was observed even after 2 hours in the polymer sample that was only pressurized without irradiating UV. Therefore, it can be seen that the recovery of the scratch appeared as a result of fluidity due to UV.

[0069] As described above in detail for specific parts of the content of the present invention, it is obvious to those having ordinary knowledge in the relevant technical field that such specific technologies are merely preferred embodiments and do not limit the scope of the present invention thereby. Therefore, the substantial scope of the present invention shall be defined by the appended claims and their equivalents. The scope of the present invention is indicated by the claims described hereinafter, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.

Claims

1. A polymer having an ultraviolet-sensitive self-healing function, comprising at least one selected from the group consisting of bisphenol-based, aminophenol-based, siloxane-based, and alicyclic epoxy resins, and a first monomer containing two or more epoxy groups, a second monomer as a curing agent, wherein the first monomer and the second monomer are bonded to cause a dynamic exchange reaction of disulfide, enabling self-healing.

2. The second monomer is a curing agent containing sulfur, and contains at least one selected from the group consisting of 4-aminophenyl disulfide, 3,3'-dihydroxydiphenyl disulfide, and 4-(2-hydroxyethoxy)phenyl disulfide. The polymer having an ultraviolet-sensitive self-healing function according to Claim 1.

3. The second monomer is represented by the following Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3: 【Chemical 1】 【Chemical 2】 [Chemical Formula 3] The polymer having an ultraviolet-sensitive self-healing function according to Claim 1.

4. Even if the polymer is damaged after curing, it enables self-healing by a dynamic exchange reaction of disulfide caused by irradiation with ultraviolet light. The polymer having an ultraviolet-sensitive self-healing function according to Claim 1.

5. The wavelength of the ultraviolet light is 250 to 260 nm. The polymer having an ultraviolet-sensitive self-healing function according to Claim 4.

6. The polymer having an ultraviolet-sensitive self-healing function according to Claim 4. The irradiation of the ultraviolet rays is performed at a temperature of room temperature for 5 to 15 minutes at an intensity of 20 to 40 mW / cm ２ 2

7. A method for producing a polymer having an ultraviolet-sensitive self-healing function, comprising a first monomer containing two or more epoxy groups, a second monomer as a curing agent, wherein the first monomer and the second monomer are bonded to cause a dynamic exchange reaction of disulfide, enabling self-healing, and the method includes: mixing and heating the first monomer and the second monomer; putting the heated mixture into a preheated mold; performing vacuum replacement on the mixture placed in the mold to remove bubbles; heating the degassed mixture to raise the temperature to obtain a cured polymer. The first monomer is a monomer containing two or more epoxy groups, and contains at least one selected from the group consisting of bisphenol-based, aminophenol-based, siloxane-based, and alicyclic epoxy resins. The method for producing a polymer having an ultraviolet-sensitive self-healing function, characterized by the above.

8. ​ The second monomer is a curing agent containing sulfur and includes one or more selected from the group consisting of 4-aminophenyl disulfide, 3,3'-dihydroxydiphenyl disulfide, and 4-(2-hydroxyethoxy)phenyl disulfide. The method for producing a polymer having an ultraviolet-sensitive self-healing function according to claim 7.

9. The second monomer is represented by the following Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3: 【Chemical Formula 4】 【Chemical Formula 5】 【Chemical Formula 6】 represented by The method for producing a polymer having an ultraviolet-sensitive self-healing function according to claim 7.

10. The step of mixing and heating the first monomer and the second monomer is performed at 95 to 105 °C for 5 to 15 minutes. The method for producing a polymer having an ultraviolet-sensitive self-healing function according to claim 7.

11. In the step of subjecting the mixture placed in the mold to vacuum replacement for degassing, vacuum replacement for degassing is performed for 10 to 20 minutes. The method for producing a polymer having an ultraviolet-sensitive self-healing function according to claim 7.

12. In the step of obtaining a cured polymer by heating the degassed mixture while raising the temperature, the temperature is raised to 140 to 160 °C and heated for 9 to 11 hours to obtain a cured polymer. The method for producing a polymer having an ultraviolet-sensitive self-healing function according to claim 7.

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