Polyamide resin curing agent and preparation method thereof

Abstract

The invention provides a polyamide resin curing agent and a preparation method thereof, the polyamide resin curing agent has a microcapsule structure, a shell polyamide resin curing agent and a core amino curing agent, and a polyacrylic acid long-chain ester layer is also arranged between the polyamide resin shell and the core amino curing agent, so that synergistic enhancement, toughening and curing promotion can be realized; the slow-release effect is realized.

Description

Technical Field

[0001] The invention belongs to the field of microcapsule curing agents, and particularly relates to a polyamide resin curing agent and a preparation method thereof. Background Art

[0002] Polyamide resin curing agent is usually a polyamide resin with a molecular weight of about 500 to 9000 formed by the polycondensation reaction of diamine and dimer acid. Depending on the type of diamine, dimer acid and the mixing ratio of the two, polyamide resin curing agents with different properties such as flexibility, impact resistance and curing properties are generated.

[0003] The curing agent is encapsulated by microencapsulation technology to hinder the curing reaction between the curing agent and the resin, thereby improving storage stability and time. Under certain temperature and pressure conditions, the microcapsules are ruptured to release the curing agent, and then a curing reaction occurs, so that the curing agent has a sustained release effect and a self-repairing effect. The preparation methods of microcapsule curing agents generally include physical methods, physical and chemical methods, and chemical methods. The physical method is simple to operate, but it has defects such as easy rupture and poor stability. The physical and chemical method mainly changes the process conditions to allow the dissolved film-forming material to precipitate from the solution, thereby encapsulating the core material into a microcapsule, but there are defects such as difficult process condition control and poor microcapsule performance. The chemical method mainly uses monomer small molecules to undergo polymerization reactions to generate polymer films, and then encapsulates the core material to prepare microcapsules. The coating effect is better, so it becomes the main preparation method. The polyamide resin curing agent is formed into a microcapsule structure, while achieving flexibility, curing properties and sustained release effects, which has not been seen in the prior art. Summary of the invention

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

[0005] The objective of the present invention is achieved through the following technical solutions: A polyamide resin curing agent has a microcapsule structure, and its preparation method comprises the following reaction steps: Step 1, 10-25 parts of acrylamide, 3-10 parts of vinyl polyamine crosslinking agent, 1-5 parts of emulsifier, and 100-200 parts of water are mixed, and solution A is prepared by ultrasonic stirring; Step 2, 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 are mixed, and solution B is prepared by ultrasonic stirring; Step 3, add solution A and 1 / 5 of solution B into the reaction kettle, ultrasonically homogenize, stir and heat to 65°C, react for 0.5h, form a core emulsion, continue to drip the remaining solution B, the dripping time is 5h, add 0.3-1.5 parts of redox initiator after the dripping is completed, continue to react for 1.5h, cool to room temperature, filter, wash, and dry to obtain polyacrylamide-acrylic acid long-chain ester nanoparticles with core-shell structure. The mass ratio of solution A to solution B is 1:3-1:10. The particle size of the polyacrylamide-acrylic acid long-chain ester nanoparticles with core-shell structure is 100-250nm.

[0006] Step 4, adding 100-300 parts of fatty diacid, 100-300 parts of polyamine, and 30-100 parts of polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure prepared in step 3 into a reaction kettle, fully stirring, continuously heating with stirring at 150rpm, the temperature is raised to 150°C, kept warm for 1h, then kept warm for 1h at intervals of 10°C, gradually heated to 220°C, kept warm for 1h, and condensed water generated by the contraction reaction is recovered to obtain a microcapsule curing agent of polyamide resin-coated polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure.

[0007] Preferably, the vinyl polyamine crosslinking agent is one or more of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0008] Preferably, the fatty diacid is one or more of adipic acid, suberic acid, sebacic acid, azelaic acid, cycloalkaneic acid, and polymerized fatty acid.

[0009] More preferably, the fatty diacid is one or more of Pripol1025, pripol 1017, PM200.

[0010] Preferably, the polyamine is one or more of ethylenediamine, N,N-dimethylpropylenediamine, meta-xylylenediamine, isophoronediamine, diethylenetriamine, diethylenetetramine, triethylenetetramine, tetramethylenediamine, hexamethylenediamine, undecadiimide, dodecamethyleneamine, 1,3-bisaminomethylenecyclohexane, 1,4-bisaminomethylcyclohexane, piperazine, imidazole and polyetheramine.

[0011] More preferably, the polyamine is one or more of p-xylylenediamine, tetramethylenediamine, and hexamethylenediamine.

[0012] Preferably, the emulsifier is one or more of SDS, SLS, OP-10, and Tween emulsifier.

[0013] A method for preparing a polyamide resin curing agent comprises the following reaction steps: Step 1, 10-25 parts of acrylamide, 3-10 parts of vinyl polyamine crosslinking agent, 1-5 parts of emulsifier, and 100-200 parts of water are mixed, and solution A is prepared by ultrasonic stirring; Step 2, 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 are mixed, and solution B is prepared by ultrasonic stirring; Step 3, add solution A and 1 / 5 of solution B into the reaction kettle, ultrasonically homogenize, stir and heat to 65°C, react for 0.5h, form a core emulsion, continue to drip the remaining solution B, the dripping time is 5h, add 0.3-1.5 parts of redox initiator after the dripping is completed, continue to react for 1.5h, cool to room temperature, filter, wash, and dry to obtain polyacrylamide-acrylic acid long-chain ester nanoparticles with core-shell structure. The mass ratio of solution A to solution B is 1:3-1:10. The particle size of the polyacrylamide-acrylic acid long-chain ester nanoparticles with core-shell structure is 100-250nm.

[0014] Step 4, adding 100-300 parts of fatty diacid, 100-300 parts of polyamine, and 30-100 parts of polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure prepared in step 3 into a reaction kettle, fully stirring, continuously heating with stirring at 150rpm, the temperature is raised to 150°C, kept warm for 1h, then kept warm for 1h at intervals of 10°C, gradually heated to 220°C, kept warm for 1h, and condensed water generated by the contraction reaction is recovered to obtain a microcapsule curing agent of polyamide resin-coated polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure.

[0015] Beneficial effects: 1. The polyamide resin curing agent of the present invention has a microcapsule structure. Polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure are prepared by a semi-continuous emulsion polymerization method, and a fatty diacid and a polyamine are subjected to an in-situ condensation reaction in the presence of the nanoparticles to form a polyamide resin shell, thereby obtaining a polyamide resin curing agent with a microcapsule structure and achieving a sustained release effect.

[0016] 2. The polyamide resin curing agent of the present invention is prepared by semi-continuous emulsion polymerization method to prepare polyacrylamide-long-chain acrylic acid ester nanoparticles with core-shell structure, and in the presence of the nanoparticles, a fatty diacid and a polyamine are subjected to in-situ condensation reaction to form a polyamide resin shell. Therefore, the prepared polyamide resin curing agent has both a shell polyamide resin curing agent and a core layer acrylamide / diethylenetriamine / / partial long-chain acrylic acid alkyl ester copolymer curing agent, and 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, which can improve toughness. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The present invention is further explained below in conjunction with specific implementation modes.

[0019] Example 1 A polyamide resin curing agent has a microcapsule structure, and its preparation method comprises the following reaction steps: Step 1: 15 parts of acrylamide, 8 parts of diethylenetriamine, 2 parts of emulsifier SDS and 100 parts of water are mixed and prepared into solution A by ultrasonic stirring; Step 2: 8 parts of dodecyl acrylate, 2 parts of emulsifier OP-10, 2 parts of initiator azobisisobutyronitrile, and 50 parts of xylene are mixed, and solution B is prepared by ultrasonic stirring; Step 3: Add solution A and 1 / 5 of solution B to the reactor, ultrasonically homogenize, stir and heat to 65°C, react for 0.5h to form a core emulsion, continue to drip the remaining solution B, the dripping time is 5h, and after the dripping is completed, add 0.8 parts of redox initiator, continue to react for 1.5h, cool to room temperature, filter, wash, and dry to obtain polyacrylamide-acrylic acid long-chain ester nanoparticles with core-shell structure. The mass ratio of solution A to solution B is 1:5. The particle size of the polyacrylamide-acrylic acid long-chain ester nanoparticles with core-shell structure is 150nm.

[0020] Step 4, add 200 parts of hydrogenated dimer acid Pripol1025 (acid value: 194mmg / KOH, Croda), 150 parts of p-xylene diamine, and 60 parts of polyacrylamide-acrylic acid long-chain ester nanoparticles with core-shell structure prepared in step 3 into the reactor, stir well, and continue to heat up under stirring at 150rpm. The temperature is raised to 150°C and kept warm for 1h, then the temperature is raised to 10°C and kept warm for 1h, and then the temperature is gradually raised to 220°C and kept warm for 1h. The condensed water generated by the contraction reaction is recovered to obtain a microcapsule curing agent of polyamide resin-coated polyacrylamide-acrylic acid long-chain ester nanoparticles with core-shell structure.

[0021] Comparative Example 1 A polyamide resin curing agent has a microcapsule structure, and its preparation method comprises the following reaction steps: Step 1: 15 parts of acrylamide, 8 parts of diethylenetriamine, 2 parts of emulsifier SDS and 100 parts of water are mixed and prepared into solution A by ultrasonic stirring; Step 2: add 1 / 5 of solution A to the reaction kettle, ultrasonically homogenize, stir and heat to 65°C, react for 0.5h to form a core emulsion, continue to drop the remaining solution A for 5h, add 0.8 parts of redox initiator after the dropwise addition is completed, continue to react for 1.5h, 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 a core-shell structure is 126nm.

[0022] Step 3, add 200 parts of hydrogenated dimer acid Pripol1025 (acid value: 194mmg / KOH, Croda), 150 parts of p-xylene diamine, and 60 parts of polyacrylamide nanoparticles with a core-shell structure prepared in step 3 into a reactor, stir well, and continue to heat up under stirring at 150rpm to 150°C, keep warm for 1h, then keep warm for 1h at every 10°C, gradually heat up to 220°C, keep warm for 1h, recover condensed water generated by the contraction reaction, and obtain a microcapsule curing agent of polyamide resin-coated polyacrylamide nanoparticles with a core-shell structure.

[0023] Comparative Example 2 A polyamide resin curing agent has a microcapsule structure, and its preparation method comprises the following reaction steps: Step 1: 8 parts of dodecyl acrylate, 2 parts of emulsifier OP-10, 2 parts of initiator azobisisobutyronitrile, and 50 parts of xylene are mixed, and solution B is prepared by ultrasonic stirring; Step 2: add 1 / 5 of solution B to the reaction kettle, ultrasonically homogenize, stir and heat to 65°C, react for 0.5h to form a core emulsion, continue to drop the remaining solution B for 5h, add 0.8 parts of redox initiator after the dropwise addition is completed, continue to react for 1.5h, 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 a core-shell structure is 119nm.

[0024] Step three, add 200 parts of hydrogenated dimer acid Pripol1025 (acid value: 194mmg / KOH, Croda), 150 parts of p-xylenediamine, and 60 parts of polyacrylic acid long-chain ester nanoparticles with a core-shell structure prepared in step three into the reactor, stir well, and continue to heat up under stirring at 150rpm to 150°C, keep warm for 1h, then keep warm for 1h at every 10°C, gradually heat up to 220°C, keep warm for 1h, recover the condensed water produced by the contraction reaction, and obtain a microcapsule curing agent of polyamide resin-coated polyacrylic acid long-chain ester nanoparticles with a core-shell structure.

[0025] Comparative Example 3 A polyamide resin curing agent, the preparation method of which comprises the following reaction steps: adding 200 parts of hydrogenated dimer acid Pripol1025 (acid value: 194 mmg / KOH, Croda) and 150 parts of p-xylenediamine into a reaction kettle, fully stirring, continuously heating up with stirring at 150 rpm, the temperature is raised to 150°C, kept warm for 1 hour, then kept warm for 1 hour at every 10°C rise, gradually raised to 220°C, kept warm for 1 hour, recovering condensed water generated by the contraction reaction, and obtaining the polyamide resin curing agent.

[0026] Performance Testing Weigh 100 parts of xylene, 75 parts of epoxy resin (Epikote 1001, epoxy equivalent of 474), and 25 parts of the microcapsule curing agent obtained in the examples and comparative examples, stir with a stirrer, and then drop the obtained epoxy resin composition on a glass slide placed on a hot plate heated to 210°C, and measure the time until the epoxy resin composition is cured. The tensile strength, elongation at break, and elongation at break after 240 months of sustained release of the coating film were measured, and the test standard was based on GB / T1040.2-2006. The results are shown in Table 1.

[0027] Table 1 Coating properties

[0028] From the comparison between Example 1 and Comparative Example 1, it can be seen that the polyamide resin curing agent prepared in Example 1 of the present application has significantly better elongation at break and sustained release effect. This may be because the present invention adopts a semi-continuous emulsion polymerization method to prepare polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure, and in the presence of the nanoparticles, a fatty diacid and a polyamine undergo an in-situ condensation reaction to form a polyamide resin shell. Therefore, the prepared polyamide resin curing agent has a microcapsule structure, and the polyamide resin shell and the core layer acrylamide / diethylenetriamine / / part of the acrylic acid long-chain alkyl ester copolymer side chains all have amino groups that have a curing agent effect. 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, enable 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 undergo a curing reaction, and inhibit the reduction of elongation at break.

[0029] From the comparison between Example 1 and Comparative Example 2, it can be seen that the polyamide resin curing agent prepared in Example 1 of the present application has significantly better tensile strength and sustained release effect. This may be because the present invention adopts a semi-continuous emulsion polymerization method to prepare polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure, and in the presence of the nanoparticles, the fatty diacid and the polyamine undergo an in-situ condensation reaction to form a polyamide resin shell, so that the prepared polyamide resin curing agent 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, enable the coating film to exhibit higher tensile strength, and can still release the reactive amino curing agent for 240 months or longer, further undergo a curing reaction, and inhibit the reduction of elongation at break.

[0030] From the comparison between Example 1 and Comparative Example 1, and between Comparative Example 2 and Comparative Example 3, it can be seen that the polyamide resin curing agent prepared in Example 1 of the present invention has a synergistic effect in terms of curing time, tensile strength, elongation at break and sustained release effect. This may be because the present invention adopts a semi-continuous emulsion polymerization method to prepare polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure, and in the presence of the nanoparticles, a fatty diacid and a polyamine undergo an in-situ condensation reaction to form a polyamide resin shell. Therefore, the prepared polyamide resin curing agent has a microcapsule structure, and has an outer shell polyamide resin curing agent and a core layer acrylamide / diethylenetriamine / / partial acrylic acid long-chain alkyl ester copolymer curing agent, and 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, which can improve toughness, and the microcapsule structure promotes curing to achieve a sustained release effect.

[0031] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in 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, 10-25 parts of acrylamide, 3-10 parts of vinyl polyamine crosslinking agent, 1-5 parts of emulsifier, and 100-200 parts of water are mixed, and solution A is prepared by ultrasonic stirring; Step 2, 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 are mixed, and solution B is prepared by ultrasonic stirring; Step 3, adding solution A and 1 / 5 of solution B into a reaction kettle, ultrasonically homogenizing, stirring and heating to 65°C, reacting for 0.5h to form a core emulsion, continuing to drop the remaining solution B for 5h, adding 0.3-1.5 parts of a redox initiator after the dropwise addition is completed, continuing the reaction for 1.5h, cooling to room temperature, filtering, washing, and drying to obtain polyacrylamide-acrylic acid long-chain ester 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-acrylic acid long-chain ester nanoparticles with a core-shell structure is 100-250nm; Step 4, adding 100-300 parts of fatty diacid, 100-300 parts of polyamine, and 30-100 parts of polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure prepared in step 3 into a reaction kettle, fully stirring, continuously heating with stirring at 150rpm, the temperature is raised to 150°C, kept warm for 1h, then kept warm for 1h at intervals of 10°C, gradually heated to 220°C, kept warm for 1h, and condensed water generated by the contraction reaction is recovered to obtain a microcapsule curing agent of polyamide resin-coated polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure.

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

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

4. The polyamide resin curing agent according to claim 3, characterized in that The fatty diacid is one or more of Pripol1025, pripol 1017 and PM200.

5. The polyamide resin curing agent according to claim 1, characterized in that The polyamine is one or more of ethylenediamine, N,N-dimethylpropylenediamine, meta-xylylenediamine, isophoronediamine, diethylenetriamine, diethylenetetramine, triethylenetetramine, tetramethylenediamine, hexamethylenediamine, undecadiimide, dodecamethyleneamine, 1,3-bisaminomethylenecyclohexane, 1,4-bisaminomethylcyclohexane, piperazine, imidazole and polyetheramine.

6. A method for preparing a polyamide resin curing agent according to any one of claims 1 to 5, characterized in that: The process comprises the following reaction steps: Step 1, 10-25 parts of acrylamide, 3-10 parts of vinyl polyamine crosslinking agent, 1-5 parts of emulsifier, and 100-200 parts of water are mixed, and solution A is prepared by ultrasonic stirring; Step 2, 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 are mixed, and solution B is prepared by ultrasonic stirring; Step 3, adding solution A and 1 / 5 of solution B into a reaction kettle, ultrasonically homogenizing, stirring and heating to 65°C, reacting for 0.5h to form a core emulsion, continuing to drop the remaining solution B for 5h, adding 0.3-1.5 parts of a redox initiator after the dropwise addition is completed, continuing the reaction for 1.5h, cooling to room temperature, filtering, washing, and drying to obtain polyacrylamide-acrylic acid long-chain ester 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-acrylic acid long-chain ester nanoparticles with a core-shell structure is 100-250nm; Step 4, adding 100-300 parts of fatty diacid, 100-300 parts of polyamine, and 30-100 parts of polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure prepared in step 3 into a reaction kettle, fully stirring, continuously heating with stirring at 150rpm, the temperature is raised to 150°C, kept warm for 1h, then kept warm for 1h at intervals of 10°C, gradually heated to 220°C, kept warm for 1h, and condensed water generated by the contraction reaction is recovered to obtain a microcapsule curing agent of polyamide resin-coated polyacrylamide-acrylic acid long-chain ester nanoparticles with a core-shell structure.

7. The method for preparing a polyamide resin curing agent according to claim 6, characterized in that: The polyamine is one or more of p-xylylenediamine, tetramethylenediamine and hexamethylenediamine.

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

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