Polyamide resin curing agent and method for producing the same

Abstract

The present application provides a kind of polyamide resin curing agent and its preparation method, it has microcapsule structure, there is also polyacrylic long chain ester layer between polyamide resin shell and core layer amino curing agent, can synergistically enhance, toughening, promote curing, and has slow-release effect.

Description

Technical Field

[0001] This invention belongs to the field of microcapsule curing agents, and specifically relates to a polyamide resin curing agent and its preparation method. Background Technology

[0002] Polyamide resin curing agents are typically polyamide resins with a molecular weight of approximately 500 to 9000, formed by the condensation reaction of diamines and dimer acids. Depending on the type of diamine, the type of dimer acid, and the mixing ratio, polyamide resin curing agents with varying properties such as flexibility, impact resistance, and curing properties are produced.

[0003] Microencapsulation technology encapsulates the curing agent to prevent the curing reaction between the curing agent and resin, thus improving storage stability and duration. Under certain temperature and pressure conditions, the microcapsules rupture, releasing the curing agent, which then undergoes a curing reaction, giving the curing agent a slow-release effect and a self-healing effect. Microencapsulated curing agents are typically prepared using physical, physicochemical, and chemical methods. Physical methods are simple to operate but suffer from drawbacks such as susceptibility to rupture and poor stability. Physicochemical methods mainly involve altering process conditions to cause dissolved film-forming materials to deposit from the solution, thereby encapsulating the core material into microcapsules; however, they suffer from difficulties in controlling process conditions and relatively poor microcapsule performance. Chemical methods primarily utilize the polymerization reaction of small monomer molecules to generate a polymer film, which is then used to encapsulate the core material to prepare microcapsules. This method offers better encapsulation results and has thus become the primary preparation method. However, the simultaneous achievement of flexibility, curability, and slow-release effects by encapsulating polyamide resin curing agents into microcapsules is not found in existing technologies. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, the purpose of this invention is to provide a polyamide resin curing agent and its preparation method, which has a microcapsule structure and has a polyamide resin curing agent in the outer shell and an amino curing agent in the core layer. There is also a polyacrylic acid long-chain ester layer between the polyamide resin outer shell and the amino curing agent in the core layer, which can synergistically enhance, toughen, and promote curing, and has a slow-release effect.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A polyamide resin curing agent having a microcapsule structure is prepared by the following reaction steps:

[0007] Step 1: Mix 10-25 parts of acrylamide, 3-10 parts of vinyl polyamine crosslinking agent, 1-5 parts of emulsifier, and 100-200 parts of water, and prepare solution A by ultrasonic stirring;

[0008] Step 2: Mix 5-25 parts of long-chain alkyl acrylate, 1-10 parts of emulsifier, 1-3 parts of initiator azobisisobutyronitrile, and 30-100 parts of xylene, and prepare solution B by ultrasonic stirring.

[0009] Step 3: Add solution A and 1 / 5 of solution B to the reaction vessel, sonicate to homogenize, stir, and heat to 65°C. React for 0.5 hours to form a core emulsion. Continue to add the remaining solution B dropwise over 5 hours. After the addition is complete, add 0.3-1.5 parts of redox initiator and continue the reaction for 1.5 hours. Cool to room temperature, filter, wash, and dry to obtain polyacrylamide-acrylate long-chain nanoparticles with a core-shell structure. The mass ratio of solution A to solution B is 1:3-1:10. The particle size of the core-shell polyacrylamide-acrylate long-chain nanoparticles is 100-250 nm.

[0010] Step four: Add 100-300 parts of fatty diacid, 100-300 parts of polyamine, and 30-100 parts of the core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles prepared in step three to the reaction vessel, stir thoroughly, and continuously heat at 150 rpm until the temperature reaches 150°C. Hold at this temperature for 1 hour, then gradually increase the temperature by 10°C and hold for 1 hour, until the temperature reaches 220°C and holds for 1 hour. Reclaim the condensate generated by the shrinkage reaction to obtain a microcapsule curing agent of polyamide resin-coated core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles.

[0011] Preferably, the vinyl polyamine crosslinking agent is one or more of diethylenetriamine, trivinyltetraamine, and tetraethylenepentamine.

[0012] Preferably, the fatty acid is one or more of adipic acid, octanoic acid, sebacic acid, azelaic acid, cycloalkanoic acid, and polymeric fatty acids.

[0013] More preferably, the fatty acid diacid is one or more of Pripol 1025, Pripol 1017, and PM200.

[0014] Preferably, the polyamine is one or more selected from ethylenediamine, N,N-dimethylpropylenediamine, m-phenylenediamine, isophorone diamine, diethylenetriamine, diethylenetetramine, triethylenetetramine, tetramethylenediamine, hexamethylenediamine, undecanediimide, dodecadimethyleneamine, 1,3-diaminomethylenecyclohexane, 1,4-diaminomethylcyclohexane, piperazine, imidazole, and polyetheramine.

[0015] More preferably, the polyamine is one or more of p-xylenediamine, tetramethylenediamine, and hexamethylenediamine.

[0016] Preferably, the emulsifier is one or more of SDS, SLS, OP-10, and Tween emulsifier.

[0017] A method for preparing a polyamide resin curing agent includes the following reaction steps:

[0018] Step 1: Mix 10-25 parts of acrylamide, 3-10 parts of vinyl polyamine crosslinking agent, 1-5 parts of emulsifier, and 100-200 parts of water, and prepare solution A by ultrasonic stirring;

[0019] Step 2: Mix 5-25 parts of long-chain alkyl acrylate, 1-10 parts of emulsifier, 1-3 parts of initiator azobisisobutyronitrile, and 30-100 parts of xylene, and prepare solution B by ultrasonic stirring.

[0020] Step 3: Add solution A and 1 / 5 of solution B to the reaction vessel, sonicate to homogenize, stir, and heat to 65°C. React for 0.5 hours to form a core emulsion. Continue to add the remaining solution B dropwise over 5 hours. After the addition is complete, add 0.3-1.5 parts of redox initiator and continue the reaction for 1.5 hours. Cool to room temperature, filter, wash, and dry to obtain polyacrylamide-acrylate long-chain nanoparticles with a core-shell structure. The mass ratio of solution A to solution B is 1:3-1:10. The particle size of the core-shell polyacrylamide-acrylate long-chain nanoparticles is 100-250 nm.

[0021] Step four: Add 100-300 parts of fatty diacid, 100-300 parts of polyamine, and 30-100 parts of the core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles prepared in step three to the reaction vessel, stir thoroughly, and continuously heat at 150 rpm until the temperature reaches 150°C. Hold at this temperature for 1 hour, then gradually increase the temperature by 10°C and hold for 1 hour, until the temperature reaches 220°C and holds for 1 hour. Reclaim the condensate generated by the shrinkage reaction to obtain a microcapsule curing agent of polyamide resin-coated core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles.

[0022] Beneficial effects:

[0023] 1. The polyamide resin curing agent of the present invention has a microcapsule structure. It is prepared by using a semi-continuous emulsion polymerization method to prepare polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure. In the presence of the nanoparticles, fatty acid diacid and polyamine undergo an in-situ condensation reaction to form a polyamide resin shell, thereby obtaining a polyamide resin curing agent with a microcapsule structure and achieving a sustained-release effect.

[0024] 2. The polyamide resin curing agent of the present invention is prepared by using a semi-continuous emulsion polymerization method to prepare polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure. In the presence of the nanoparticles, fatty acid diacid and polyamine undergo an in-situ condensation reaction to form a polyamide resin shell. Therefore, the polyamide resin curing agent prepared has both a shell polyamide resin curing agent and a core layer acrylamide / diethylenetriamine / / partially acrylic acid long-chain alkyl ester copolymer curing agent. There is also a polyacrylic acid long-chain ester layer between the polyamide resin shell and the core layer amino curing agent. The nanoparticles can play a reinforcing role, and the polyacrylic acid long-chain ester layer is a soft segment that can improve toughness. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The present invention will be further explained below with reference to specific embodiments.

[0027] Example 1

[0028] A polyamide resin curing agent having a microcapsule structure is prepared by the following reaction steps:

[0029] Step 1: Mix 15 parts acrylamide, 8 parts diethylenetriamine, 2 parts emulsifier SDS, and 100 parts water, and prepare solution A by ultrasonic stirring;

[0030] Step 2: Mix 8 parts of dodecyl acrylate, 2 parts of emulsifier OP-10, 2 parts of initiator azobisisobutyronitrile, and 50 parts of xylene, and prepare solution B by ultrasonic stirring;

[0031] Step 3: Add solution A and 1 / 5 of solution B to the reaction vessel, sonicate to homogenize, stir, and heat to 65°C. React for 0.5 hours to form a core emulsion. Continue to add the remaining solution B dropwise over 5 hours. After the addition is complete, add 0.8 parts of redox initiator and continue the reaction for 1.5 hours. Cool to room temperature, filter, wash, and dry to obtain polyacrylamide-acrylate long-chain nanoparticles with a core-shell structure. The mass ratio of solution A to solution B is 1:5. The particle size of the core-shell polyacrylamide-acrylate long-chain nanoparticles is 150 nm.

[0032] Step four: 200 parts of hydrogenated dimer acid Pripol 1025 (acid value: 194 mmg / KOH, Kroda), 150 parts of p-xylenediamine, and 60 parts of the core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles prepared in step three were added to the reaction vessel and stirred thoroughly. The temperature was continuously increased to 150℃ under stirring at 150 rpm and held for 1 hour. Then, the temperature was gradually increased to 220℃ and held for 1 hour at a rate of 10℃ per hour. The condensate generated by the shrinkage reaction was then reabsorbed to obtain a microcapsule curing agent of polyamide resin-coated core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles.

[0033] Comparative Example 1

[0034] A polyamide resin curing agent having a microcapsule structure is prepared by the following reaction steps:

[0035] Step 1: Mix 15 parts acrylamide, 8 parts diethylenetriamine, 2 parts emulsifier SDS, and 100 parts water, and prepare solution A by ultrasonic stirring;

[0036] Step two: Add 1 / 5 of solution A to the reaction vessel, sonicate to homogenize, stir, and heat to 65°C. React for 0.5 hours to form a core emulsion. Continue to add the remaining solution A dropwise over 5 hours. After the addition is complete, add 0.8 parts of redox initiator and continue the reaction for 1.5 hours. Cool to room temperature, filter, wash, and dry to obtain polyacrylamide nanoparticles with a core-shell structure. The particle size of the polyacrylamide nanoparticles with the core-shell structure is 126 nm.

[0037] Step 3: 200 parts of hydrogenated dimer acid Pripol 1025 (acid value: 194 mmg / KOH, Kroda), 150 parts of p-xylenediamine, and 60 parts of the core-shell structured polyacrylamide nanoparticles prepared in Step 3 were added to the reaction vessel and stirred thoroughly. The temperature was continuously increased to 150°C under stirring at 150 rpm and held for 1 hour. Then, the temperature was gradually increased to 220°C and held for 1 hour at a rate of 10°C per hour. The condensate generated by the shrinkage reaction was then reabsorbed to obtain a microcapsule curing agent of polyamide resin-coated core-shell structured polyacrylamide nanoparticles.

[0038] Comparative Example 2

[0039] A polyamide resin curing agent having a microcapsule structure is prepared by the following reaction steps:

[0040] Step 1: Mix 8 parts of dodecyl acrylate, 2 parts of emulsifier OP-10, 2 parts of initiator azobisisobutyronitrile, and 50 parts of xylene, and prepare solution B by ultrasonic stirring;

[0041] Step two: Add 1 / 5 of solution B to the reaction vessel, sonicate to homogenize, stir, and heat to 65°C. React for 0.5 hours to form a core emulsion. Continue to add the remaining solution B dropwise over 5 hours. After the addition is complete, add 0.8 parts of redox initiator and continue the reaction for 1.5 hours. Cool to room temperature, filter, wash, and dry to obtain polyacrylic acid long-chain ester nanoparticles with a core-shell structure. The particle size of the polyacrylic acid long-chain ester nanoparticles with the core-shell structure is 119 nm.

[0042] Step 3: 200 parts of hydrogenated dimer acid Pripol 1025 (acid value: 194 mmg / KOH, Kroda), 150 parts of p-xylenediamine, and 60 parts of the core-shell structured polyacrylic acid long-chain ester nanoparticles prepared in Step 3 were added to the reaction vessel and stirred thoroughly. The temperature was continuously increased to 150℃ under stirring at 150 rpm and held for 1 hour. Then, the temperature was gradually increased to 220℃ and held for 1 hour at a rate of 10℃ per hour. The condensate generated by the shrinkage reaction was then reabsorbed to obtain a microcapsule curing agent of polyamide resin-coated core-shell structured polyacrylic acid long-chain ester nanoparticles.

[0043] Comparative Example 3

[0044] A polyamide resin curing agent is prepared by the following reaction steps: 200 parts of hydrogenated dimer acid Pripol 1025 (acid value: 194 mmg / KOH, Kroda) and 150 parts of p-xylenediamine are added to a reaction vessel and stirred thoroughly. The temperature is continuously increased to 150°C under stirring at 150 rpm and held for 1 hour. Then, the temperature is gradually increased to 220°C and held for 1 hour at a rate of 10°C per hour. The condensate generated by the shrinkage reaction is then removed to obtain the polyamide resin curing agent.

[0045] Performance testing

[0046] 100 parts xylene, 75 parts epoxy resin (Epikote 1001, epoxy equivalent 474), and 25 parts microcapsule curing agent obtained in the examples and comparative examples were weighed. After stirring with a stirrer, the resulting epoxy resin composition was dropped onto a glass slide placed on a hot plate heated to 210°C, and the time until the epoxy resin composition cured was measured. The tensile strength, elongation at break, and elongation at break of the coating film after 240 months of sustained release were measured. The test standard was GB / T1040.2-2006, and the results are shown in Table 1.

[0047] Table 1 Coating performance

[0048]

[0049] A comparison of Example 1 and Comparative Example 1 shows that the polyamide resin curing agent prepared in Example 1 of this application has significantly better elongation at break and sustained-release effect. This may be because the present invention uses a semi-continuous emulsion polymerization method with core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles, and in the presence of these nanoparticles, fatty acid diacid and polyamine undergo in-situ condensation reaction to form a polyamide resin shell. Therefore, the prepared polyamide resin curing agent has a microcapsule structure, and both the polyamide resin shell and the core layer acrylamide / diethylenetriamine / / partially acrylic acid long-chain alkyl ester copolymer side chains have amino groups that act as curing agents. Compared with Comparative Example 1, Example 1 also has a polyacrylic acid long-chain ester layer between the polyamide resin shell and the core layer amino curing agent, which can improve the toughness and sustained-release effect of the polyamide resin curing agent of the present invention, enabling the coating film to exhibit better elongation at break, and can still release the reactive amino curing agent effect for 240 months or longer, further undergoing a curing reaction and inhibiting the decrease in elongation at break.

[0050] A comparison of Example 1 and Comparative Example 2 shows that the polyamide resin curing agent prepared in Example 1 of this application has significantly better tensile strength and sustained-release effect. This may be because the present invention uses a semi-continuous emulsion polymerization method with core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles, and in the presence of these nanoparticles, fatty acid diacid and polyamine undergo in-situ condensation reaction to form a polyamide resin shell. Therefore, the polyamide resin curing agent prepared has a microcapsule structure. Compared with Comparative Example 2, Example 1 also has a core layer amino curing agent, which can improve the strength and sustained-release effect of the polyamide resin curing agent of the present invention, enabling the coating film to exhibit higher tensile strength, and can still release the reactive amino curing agent for 240 months or longer, further undergoing a curing reaction and inhibiting the decrease in elongation at break.

[0051] A comparison of Example 1 with Comparative Examples 1, 2, and 3 shows that the polyamide resin curing agent prepared in Example 1 of this invention exhibits a synergistic effect in terms of curing time, tensile strength, elongation at break, and sustained-release effect. This may be because this invention uses a semi-continuous emulsion polymerization method to prepare polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure. In the presence of these nanoparticles, fatty diacid and polyamine undergo an in-situ condensation reaction to form a polyamide resin shell. Therefore, the prepared polyamide resin curing agent has a microcapsule structure, possessing both a shell polyamide resin curing agent and a core layer of acrylamide / diethylenetriamine / / partially acrylic acid long-chain alkyl ester copolymer curing agent. Furthermore, there is a polyacrylic acid long-chain ester layer between the polyamide resin shell and the core layer amino curing agent. The nanoparticles can play a reinforcing role, and the polyacrylic acid long-chain ester layer, being a soft segment, can improve toughness. Moreover, the microcapsule structure promotes curing, achieving a sustained-release effect.

[0052] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A polyamide resin curing agent, characterized in that, It has a microcapsule structure, and its preparation method includes the following reaction steps: Step 1: Mix 10-25 parts of acrylamide, 3-10 parts of vinyl polyamine crosslinking agent, 1-5 parts of emulsifier, and 100-200 parts of water, and prepare solution A by ultrasonic stirring; Step 2: Mix 5-25 parts of long-chain alkyl acrylate, 1-10 parts of emulsifier, 1-3 parts of initiator azobisisobutyronitrile, and 30-100 parts of xylene, and prepare solution B by ultrasonic stirring. Step 3: Add solution A and 1 / 5 of solution B to the reaction vessel, sonicate to homogenize, stir and heat to 65℃, react for 0.5h to form a core emulsion, continue to add the remaining solution B dropwise over 5h, after which add 0.3-1.5 parts of redox initiator, continue the reaction for 1.5h, cool to room temperature, filter, wash, and dry to obtain polyacrylamide-acrylate long-chain nanoparticles with a core-shell structure; the mass ratio of solution A to solution B is 1:3-1:10, and the particle size of the polyacrylamide-acrylate long-chain nanoparticles with a core-shell structure is 100-250nm; Step four: Add 100-300 parts of fatty diacid, 100-300 parts of polyamine, and 30-100 parts of the core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles prepared in step three to the reaction vessel, stir thoroughly, and continuously heat at 150 rpm until the temperature reaches 150°C. Hold at this temperature for 1 hour, then gradually increase the temperature by 10°C and hold for 1 hour, until the temperature reaches 220°C and holds for 1 hour. Reclaim the condensate generated by the shrinkage reaction to obtain a microcapsule curing agent of polyamide resin-coated core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles.

2. The polyamide resin curing agent according to claim 1, characterized in that, The vinyl polyamine crosslinking agent is one or more of diethylenetriamine, trivinyltetraamine, and tetraethylenepentamine.

3. The polyamide resin curing agent according to claim 1, characterized in that, The fatty acid diacid is one or more of adipic acid, octanoic acid, sebacic acid, azelaic acid, and polymeric fatty acids.

4. The polyamide resin curing agent according to claim 3, characterized in that, The fatty acid diacid is one or more of Pripol 1025 and Pripol 1017.

5. The polyamide resin curing agent according to claim 1, characterized in that, The polyamine is one or more selected from p-xylenediamine, ethylenediamine, N,N-dimethylpropylenediamine, m-phenylenediamine, isophoronediamine, diethylenetriamine, triethylenetetramine, 1,3-diaminomethylenecyclohexane, 1,4-diaminomethylcyclohexane, and polyetheramine.

6. A method for preparing the polyamide resin curing agent according to any one of claims 1-5, characterized in that, The reaction steps include the following: Step 1: Mix 10-25 parts of acrylamide, 3-10 parts of vinyl polyamine crosslinking agent, 1-5 parts of emulsifier, and 100-200 parts of water, and prepare solution A by ultrasonic stirring; Step 2: Mix 5-25 parts of long-chain alkyl acrylate, 1-10 parts of emulsifier, 1-3 parts of initiator azobisisobutyronitrile, and 30-100 parts of xylene, and prepare solution B by ultrasonic stirring. Step 3: Add solution A and 1 / 5 of solution B to the reaction vessel, sonicate to homogenize, stir and heat to 65℃, react for 0.5h to form a core emulsion, continue to add the remaining solution B dropwise over 5h, after which add 0.3-1.5 parts of redox initiator, continue the reaction for 1.5h, cool to room temperature, filter, wash, and dry to obtain polyacrylamide-acrylate long-chain nanoparticles with a core-shell structure; the mass ratio of solution A to solution B is 1:3-1:10, and the particle size of the polyacrylamide-acrylate long-chain nanoparticles with a core-shell structure is 100-250nm; Step four: Add 100-300 parts of fatty diacid, 100-300 parts of polyamine, and 30-100 parts of the core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles prepared in step three to the reaction vessel, stir thoroughly, and continuously heat at 150 rpm until the temperature reaches 150°C. Hold at this temperature for 1 hour, then gradually increase the temperature by 10°C and hold for 1 hour, until the temperature reaches 220°C and holds for 1 hour. Reclaim the condensate generated by the shrinkage reaction to obtain a microcapsule curing agent of polyamide resin-coated core-shell structured polyacrylamide-acrylic acid long-chain ester nanoparticles.

7. The method for preparing the polyamide resin curing agent according to claim 6, characterized in that, The emulsifier is one or more of OP-10, Tween, and SDS.

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