Modified dicyandiamide curing agent as well as preparation method and application thereof
By mixing modified dicyandiamide curing agent with acrylic resin, the problems of poor toughness and high viscosity of acrylic resin during the curing process were solved, achieving complete curing and performance stability of non-silicone thermally conductive materials, and improving toughness and heat resistance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU HI TECH ELECTRONICS CO LTD
- Filing Date
- 2026-01-30
- Publication Date
- 2026-05-12
AI Technical Summary
During the curing process, acrylic resin has a rigid cross-linked network skeleton, which makes it difficult for molecular chains to slide relative to each other. This can easily cause coating cracking, poor toughness, high viscosity, and difficulty in processing. Existing toughening processes are complex and cannot meet the application requirements of non-silicon thermal conductive materials.
A modified dicyandiamide curing agent is used, which is prepared by reacting dicyandiamide and styrene. This reduces intermolecular polarity, introduces large substituents and short-branched structures, improves toughness and reduces viscosity. It is then mixed with acrylic resin, aluminum powder and other materials to prepare a non-silicon thermally conductive material.
It achieves complete curing of non-silicon thermally conductive materials, with high structural consistency, uniform internal stress, improved toughness, shortened curing time, improved resistance to damp heat, stable performance after high-temperature aging, and minimal change in hardness.
Smart Images
Figure CN122010787A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer technology, specifically relating to a modified dicyandiamide curing agent, its preparation method, and its application. Background Technology
[0002] Acrylic resins possess excellent mechanical properties, weather resistance, and electrical insulation, making them widely used in coatings and adhesives. They are among the most commonly used resins in high-performance resin-based composite materials. Furthermore, due to the presence of carbon-carbon double bonds and ester groups in their structure, acrylic resins exhibit thermosetting properties, allowing them to form various high-performance cured products with different curing agents, catalysts, and additives. They can also undergo substitution or addition reactions with various compounds containing active hydrogen, curing and cross-linking to form a network structure. In non-silicone thermal conductive materials, acrylic resins completely avoid the problems of silicone oil volatilization and leakage found in traditional thermal conductive materials. Simultaneously, their high compressibility allows for closer contact between the heat source and the thermal conductive material, resulting in a higher deformation capacity. Non-silicone thermal conductive materials need to remain unchanged for 1000 hours at 130°C during the aging process. However, the cross-linked network skeleton is rigid during the curing process, which makes it difficult for the molecular chains to slide relative to each other. This can easily cause the accumulation of internal stress in the coating during the drying process, leading to cracking of the coating. The toughness is relatively poor, and the hardness after curing is high. It is not an ideal choice for applications that require high impact resistance. At the same time, acrylic resin has high viscosity and is not easy to process. The mixing, molding and curing processes require complex processes.
[0003] Currently, toughening of acrylic resins mainly involves introducing toughening agents such as core-shell rubber, thermoplastic resins, and hyperbranched resins, or forming interpenetrating polymer networks during the curing process of acrylic resins to achieve toughening effects and improve mechanical properties. However, most current toughening processes are complex to operate, increase system viscosity, and have long curing times, making them difficult to meet the requirements for applications in non-silicone thermally conductive materials.
[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention
[0005] The purpose of this invention is to provide a modified dicyandiamide curing agent that enables more complete curing of the cured product and improves the toughness of the cured product.
[0006] To achieve the above objectives, a specific embodiment of the present invention provides a modified dicyandiamide curing agent, which is synthesized from at least 10 to 20 parts by weight of dicyandiamide and 12 to 24 parts by weight of styrene. The structural formula of the modified dicyandiamide curing agent is as follows:
[0007] .
[0008] Another specific embodiment of the present invention provides a method for preparing the above-mentioned modified dicyandiamide curing agent, comprising: weighing 10 to 20 parts by mass of dicyandiamide and dissolving it in N,N-dimethylformamide to obtain a first reaction solution; weighing 12 to 24 parts by mass of styrene and dissolving it in toluene to obtain a second reaction solution; adding the second reaction solution dropwise to the first reaction solution by titration, and maintaining the temperature continuously after the addition is completed to obtain a curing agent solution; after the first reaction solution and the second reaction solution have reacted, evaporating the solvent in the curing agent solution and washing and drying it to obtain the modified dicyandiamide curing agent.
[0009] In one or more embodiments of the present invention, the amount of N,N-dimethylformamide used is 100 to 120 parts by weight.
[0010] In one or more embodiments of the present invention, the amount of toluene used is 100 to 150 parts by weight.
[0011] In one or more embodiments of the present invention, the reaction temperature and the holding temperature of the second reaction solution and the first reaction solution are 70 to 80°C.
[0012] In one or more embodiments of the present invention, the second reaction solution and the first reaction solution react under ultrasonic conditions.
[0013] In one or more embodiments of the present invention, the dropping rate of the second reaction solution is 30 to 42 drops / min.
[0014] Compared with existing technologies, the modified dicyandiamide curing agent preparation method of the present invention utilizes styrene to modify dicyandiamide, thereby reducing the polarity between molecules and resulting in a more uniform distribution of active sites, leading to more complete curing and higher structural consistency of the cured product. The structure of styrene allows for larger substituents on the modified dicyandiamide curing agent, restricting the rotational mobility of the chain segments. Shortening the branching increases the interchain spacing, enlarges the free volume, prevents intermolecular slippage, and improves the toughness of the cured product.
[0015] Another specific embodiment of the present invention provides a method for preparing a non-silicone thermally conductive material, comprising mixing 1 to 1.5 parts by weight of a modified dicyandiamide curing agent prepared by the above-described preparation method, 2 to 6 parts by weight of N,N-dimethylformamide, 6 to 10 parts by weight of acrylic resin, and 88 to 93 parts by weight of aluminum powder, and heating to 95 to 105°C while stirring to obtain a mixture. The mixture is then uniformly coated onto a release film, and after setting, a non-silicone thermally conductive material is obtained.
[0016] In one or more embodiments of the present invention, the acrylic resin is selected from one or more of pure acrylic resin, styrene-acrylic resin and silicone-acrylic resin.
[0017] Another specific embodiment of the present invention provides a non-silicon thermally conductive material prepared by the above-described preparation method.
[0018] Compared with existing technologies, the preparation method and the non-silicone thermally conductive material of this invention utilize a modified dicyandiamide curing agent. This modified dicyandiamide curing agent is easily dispersed in resin at high temperatures, and its intermolecular polarity decreases, resulting in a more uniform distribution of active sites. This leads to more complete curing of the non-silicone thermally conductive material, a more consistent structure, uniform internal stress distribution, fewer defects, and a high degree of crosslinking. Simultaneously, the modified dicyandiamide curing agent introduces a phenylethane structure with large substituents, restricting the rotational mobility of chain segments. Shortened branching increases interchain spacing, increases free volume, prevents intermolecular slippage, and improves the toughness of the non-silicone thermally conductive material. Furthermore, the introduction of the modified dicyandiamide curing agent reduces the curing time of the non-silicone thermally conductive material, improves its resistance to damp heat, and reduces the system viscosity. After high-temperature aging, the thermal conductivity of the non-silicone thermally conductive material remains below 10%, and the hardness remains below 5%, demonstrating more stable performance. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is an infrared spectrum of the modified dicyandiamide curing agent in one embodiment of the present invention;
[0021] Figure 2 This is a flowchart of a method for preparing a modified dicyandiamide curing agent according to an embodiment of the present invention. Detailed Implementation
[0022] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.
[0023] A modified dicyandiamide curing agent according to one embodiment of the present invention is synthesized from at least 10 to 20 parts by weight of dicyandiamide and 12 to 24 parts by weight of styrene. The structural formula of the modified dicyandiamide curing agent is as follows:
[0024] .
[0025] The reaction mechanism between dicyandiamide and styrene is shown below:
[0026] .
[0027] in, Figure 1 This is the infrared spectrum of the modified dicyandiamide curing agent. The 2928 cm⁻¹ in the infrared spectrum... -1 The characteristic peak at that location corresponds to the benzene ring structure introduced in the modified dicyandiamide curing agent.
[0028] This modified dicyandiamide curing process utilizes styrene to modify dicyandiamide, resulting in decreased polarity between dicyandiamide curing agent molecules and a more uniform distribution of active sites. This leads to more complete curing and higher structural consistency in the cured product. The structure of styrene allows for larger substituents on the modified dicyandiamide curing agent, restricting the rotational mobility of the chain segments. Shortening the branching increases the interchain spacing, enlarges the free volume, prevents intermolecular slippage, and improves the toughness of the cured product.
[0029] like Figure 2 As shown, another embodiment of the present invention provides a method for preparing a modified dicyandiamide curing agent, which includes steps S1 to S4.
[0030] Step S1: Weigh 10 to 20 parts by mass of dicyandiamide and dissolve it in N,N-dimethylformamide to obtain the first reaction solution.
[0031] Specifically, in step S1, 10 to 20 parts by mass of dicyandiamide are weighed and dissolved in 100 to 120 parts by mass of N,N-dimethylformamide to obtain the first reaction solution.
[0032] Step S2: Weigh 12 to 24 parts by mass of styrene and dissolve it in toluene to obtain the second reaction solution.
[0033] Specifically, in step S2, 12 to 24 parts by mass of styrene are weighed and dissolved in 100 to 150 parts by mass of toluene to obtain a second reaction solution.
[0034] Step S3: The second reaction solution is added to the first reaction solution by titration. After the addition is completed, the solution is kept warm to obtain the curing agent solution.
[0035] Specifically, in step S3, under temperature and ultrasonic conditions of 70 to 80°C, the second reaction liquid is added to the first reaction liquid by titration at a rate of 30 to 42 drops / min. After the addition is completed, the temperature is maintained at 70 to 80°C for 2 to 3 hours to obtain a curing agent solution.
[0036] Controlling the reaction temperature and holding temperature can improve the reaction yield and control side reactions. Using titration in the second reaction solution ensures a uniform concentration change in the reaction system, preventing excessively high local concentrations that could lead to overly vigorous reactions, thus improving reaction stability. Controlling the dropping rate to 30 to 42 drops / min allows for precise regulation of the reaction process, ensuring it proceeds at an appropriate rate. Conducting the reaction under ultrasonic conditions utilizes the cavitation effect generated by ultrasound to promote collision frequency and energy transfer between reactant molecules, breaking chemical bonds and improving reaction efficiency.
[0037] Step S4: After the first and second reaction solutions have reacted, the solvent in the curing agent solution is evaporated, and the solution is washed and dried to obtain the modified dicyandiamide curing agent.
[0038] Specifically, in step S4, after the first reaction solution and the second reaction solution have reacted, the solvent in the curing agent solution is evaporated, the product is cleaned and dried to obtain the modified dicyandiamide curing agent.
[0039] This method utilizes styrene to modify dicyandiamide, resulting in a decrease in the polarity between the molecules of the modified dicyandiamide curing agent and a more uniform distribution of active sites. The structure of styrene allows for larger substituents on the modified dicyandiamide curing agent, restricting the rotational mobility of the chain segments.
[0040] Another embodiment of the present invention provides a method for preparing a non-silicon thermally conductive material, which includes steps S(1) to S(2).
[0041] Step S (1): Mix 1 to 1.5 parts by weight of the above-mentioned modified dicyandiamide curing agent, 2 to 6 parts by weight of N,N-dimethylformamide, 6 to 10 parts by weight of acrylic resin and 88 to 93 parts by weight of aluminum powder and heat to 95 to 105°C and stir to obtain a mixture.
[0042] Specifically, in step S(1), 1 to 1.5 parts by weight of the modified dicyandiamide curing agent, 2 to 6 parts by weight of N,N-dimethylformamide, 6 to 10 parts by weight of acrylic resin, and 88 to 93 parts by weight of aluminum powder are mixed and heated to 95 to 105°C while stirring to obtain a mixture. The acrylic resin may be one or more of pure acrylic resin, styrene-acrylic resin, and silicone-acrylic resin.
[0043] Step S (2): The mixture is evenly coated on the release film, and after it is set, a non-silicon thermally conductive material is obtained.
[0044] Specifically, in step S(2), the mixture is uniformly coated on the release film, and after it is set, another release film can be covered on the surface to obtain a non-silicon thermal conductive material.
[0045] The reaction mechanism is as follows, where the resin is represented in the form of acrylic resin monomer:
[0046]
[0047] Another embodiment of the present invention provides a non-silicon thermally conductive material prepared by a preparation method.
[0048] The present invention will be further described below with reference to specific embodiments and comparative examples.
[0049] Example 1
[0050] Preparation of modified dicyandiamide curing agent
[0051] Step S1: Weigh 10g of dicyandiamide and dissolve it in 100g of organic solvent N,N-dimethylformamide to obtain the first reaction solution. Step S2: Weigh 12g of styrene and dissolve it in 100g of toluene to obtain the second reaction solution. Step S3: Under ultrasonic conditions at 80℃, add the second reaction solution to the first reaction solution by titration at a rate of 30 drops / min. After the addition is complete, continue the reaction at 80℃ for 2 hours to obtain the curing agent solution. Step S4: After the reaction is complete, evaporate the solvent in the curing agent solution, wash and dry the product to obtain the modified dicyandiamide curing agent.
[0052] Preparation of non-silicon thermally conductive materials
[0053] Mix 1g of modified dicyandiamide curing agent, 2g of N,N-dimethylformamide, 6g of pure acrylic resin and 88.7g of aluminum powder evenly, heat to 100℃ and stir, then coat evenly on the release film. After it is completely set, cover it with a lighter release film to obtain a non-silicone thermal conductive material with a thickness of 1.0mm.
[0054] Example 2
[0055] Preparation of modified dicyandiamide curing agent
[0056] Step S1: Weigh 20g of dicyandiamide and dissolve it in 120g of organic solvent N,N-dimethylformamide to obtain the first reaction solution. Step S2: Weigh 24g of styrene and dissolve it in 150g of toluene to obtain the second reaction solution. Step S3: Under ultrasonic conditions at 80℃, add the second reaction solution to the first reaction solution by titration at a rate of 42 drops / min. After the addition is complete, continue the reaction at 80℃ for 2 hours to obtain the curing agent solution. Step S4: After the reaction is complete, evaporate the solvent in the curing agent solution, wash and dry the product to obtain the modified dicyandiamide curing agent.
[0057] Preparation of non-silicon thermally conductive materials
[0058] Mix 1.5g of modified dicyandiamide curing agent, 6g of N,N-dimethylformyl, 9.8g of pure acrylic resin and 93g of aluminum powder evenly, heat to 100℃ and stir, then coat evenly on the release film. After it is completely set, cover it with a lighter release film to obtain a non-silicone thermal conductive material with a thickness of 1.0mm.
[0059] Comparative Example 1
[0060] Using dicyandiamide curing agent, 1g of dicyandiamide curing agent, 2g of N,N-dimethylformamide, 6g of pure acrylic resin and 88.7g of aluminum powder are mixed evenly, heated to 100℃ and stirred, and evenly coated on the release film. After it is completely set, a lighter release film is then covered to obtain a non-silicone thermal conductive material with a thickness of 1.0mm.
[0061] The performance of the non-silicon thermally conductive materials prepared in Examples 1-2 and Comparative Example 1 was tested, and the specific test results are shown in Table 1 below.
[0062] Table 1. Relevant properties of the non-silicon thermally conductive materials in Examples 1-2 and Comparative Example 1
[0063]
[0064] As shown in Table 1 above, compared with the non-silicon thermally conductive material of Comparative Example 1, Examples 1-2 have better thermal conductivity, lower thermal resistance, and minimal change in hardness after high temperature, and better high-temperature resistance.
[0065] In summary, the preparation method and the non-silicone thermally conductive material of this invention utilize a modified dicyandiamide curing agent. This modified dicyandiamide curing agent is easily dispersed in resin at high temperatures, and its intermolecular polarity decreases, resulting in a more uniform distribution of active sites. This leads to more complete curing of the non-silicone thermally conductive material, a more consistent structure, uniform internal stress distribution, fewer defects, and a high degree of crosslinking. Furthermore, the modified dicyandiamide curing agent introduces a phenylethane structure with larger substituents, restricting the rotational mobility of chain segments. Shortened branching increases interchain spacing, increases free volume, prevents intermolecular slippage, and improves the toughness of the non-silicone thermally conductive material. Moreover, the introduction of the modified dicyandiamide curing agent reduces the curing time of the non-silicone thermally conductive material, improves its resistance to damp heat, and reduces the system viscosity. After high-temperature aging, the change in thermal conductivity remains below 10%, and the change in hardness remains below 5%, indicating more stable performance.
[0066] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0067] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A modified dicyandiamide curing agent, characterized in that, It is synthesized from at least 10 to 20 parts by weight of dicyandiamide and 12 to 24 parts by weight of styrene, and the modified dicyandiamide curing agent has the following structural formula: 。 2. A method for preparing the modified dicyandiamide curing agent according to claim 1, characterized in that, include: Weigh 10 to 20 parts by mass of dicyandiamide and dissolve it in N,N-dimethylformamide to obtain the first reaction solution; Weigh 12 to 24 parts by mass of styrene and dissolve it in toluene to obtain a second reaction solution; The second reaction solution is added to the first reaction solution by titration, and the solution is kept at a constant temperature after the addition is completed to obtain the curing agent solution. After the first and second reaction solutions have reacted completely, the solvent in the curing agent solution is evaporated, and the solution is washed and dried to obtain the modified dicyandiamide curing agent.
3. The preparation method of the modified dicyandiamide curing agent as described in claim 2, characterized in that, The amount of N,N-dimethylformamide used is 100 to 120 parts by weight.
4. The preparation method of the modified dicyandiamide curing agent as described in claim 2, characterized in that, The amount of toluene used is 100 to 150 parts by weight.
5. The preparation method of the modified dicyandiamide curing agent as described in claim 2, characterized in that, The reaction temperature and holding temperature of the second reaction solution and the first reaction solution are 70 to 80°C.
6. The preparation method of the modified dicyandiamide curing agent as described in claim 2, characterized in that, The second reaction solution and the first reaction solution react under ultrasonic conditions.
7. The method for preparing the modified dicyandiamide curing agent as described in claim 2, characterized in that, The dropping rate of the second reaction solution is 30 to 42 drops / min.
8. A method for preparing a non-silicon thermally conductive material, characterized in that, include: Mix 1 to 1.5 parts by weight of the modified dicyandiamide curing agent prepared by any one of claims 3-7, 2 to 6 parts by weight of N,N-dimethylformamide, 6 to 10 parts by weight of acrylic resin and 88 to 93 parts by weight of aluminum powder and heat to 95 to 105°C while stirring to obtain a mixture. The mixture is uniformly coated onto a release film, and after setting, a non-silicon thermally conductive material is obtained.
9. The method for preparing the non-silicon thermally conductive material as described in claim 8, characterized in that, The acrylic resin is selected from one or more of pure acrylic resin, styrene-acrylic resin, and silicone-acrylic resin.
10. A non-silicon thermally conductive material prepared using the preparation method of claim 9.