A spiro polyamide epoxy resin curing agent and its preparation method and application

Abstract

The present invention provides a method for preparing a novel epoxy resin curing agent. A compound containing a terminal dicarboxyl group is synthesized using a thiol-vinyl addition reaction, and then subjected to a polycondensation reaction with ethylenediamine to obtain a polyamide containing a spirocyclic structure as an epoxy resin curing agent. Compared with existing polyamide curing agents, the curing agent prepared by the present invention has a spirocyclic and thioether bond structure that can better improve the toughness of the cured product, and has the characteristics of polyamide curing agents, such as room temperature curing and high adhesion of the cured product.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a spiro polyamide epoxy resin curing agent, a preparation method and an application thereof. Background Art

[0002] Epoxy resins are oligomers containing two or more epoxy groups in their molecular structure, with a cycloaliphatic or aromatic chemical structure as their backbone. They can form thermosetting products through a cross-linking reaction between the epoxy groups and a curing agent. The resulting thermosetting polymers exhibit excellent mechanical and physical properties, thermal and chemical stability, electrical insulation, and moldability, and are widely used in aerospace structural components, electronic packaging materials, coatings, adhesives, and other fields. Curing agents play an indispensable, and even, to some extent, decisive, role in the application of epoxy resins.

[0003] Electronic packaging technology is increasingly being used in electronic devices, particularly as trends drive optimized electronic component layout, highly integrated functionality, miniaturization, and increasingly harsh application environments. Cured epoxy resin products possess excellent mechanical and physical properties, and the resulting packaging offers excellent water resistance, high-temperature resistance, and excellent insulation. However, epoxy resin, as a packaging material, still faces challenges, primarily due to its brittleness and poor adhesion, which hinder its ability to meet these requirements. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a spiro polyamide epoxy resin curing agent and its preparation method and application. The curing agent provided by the present invention can make the prepared epoxy resin have better toughness and adhesion.

[0005] The present invention provides a method for preparing a spiro polyamide epoxy resin curing agent, comprising:

[0006] Under the action of an initiator, diacryl acetal pentaerythritol and a carboxyl-containing thiol compound are subjected to a first reaction in methanol to obtain a reaction intermediate product;

[0007] The reaction intermediate product and aliphatic diamine are subjected to a second reaction in a solvent to obtain a spiropolyamide epoxy resin curing agent.

[0008] Preferably, the first reaction is carried out under the protection of nitrogen;

[0009] The temperature of the first reaction is 50-70° C., and the time is 3-6 hours.

[0010] Preferably, the second reaction preferably comprises:

[0011] First react at a first temperature and then raise the temperature to a second temperature to continue the reaction;

[0012] The first temperature is 45-55°C, and the second temperature is 125-135°C.

[0013] Preferably, the carboxyl-containing thiol compound is a monothiol compound, selected from one or more of 2-mercaptopropionic acid, 3-mercaptopropionic acid, 4-mercaptobutyric acid, 3-mercaptoisobutyric acid, 5-mercaptovaleric acid, and 6-mercaptohexanoic acid.

[0014] Preferably, the initiator is a free radical initiator selected from one of dibenzoyl peroxide, dodecyl peroxide, dicyclohexyl peroxydicarbonate, azobisisobutyronitrile, azobisisoheptanenitrile, methyl vinyl ketone, benzoin, benzoin dimethyl ether, benzophenone or eosin.

[0015] Preferably, the aliphatic diamine is one or more selected from ethylenediamine, propylenediamine, pentanediamine, hexamethylenediamine, 1,2-cycloethylenediamine, 2-methylpentanediamine and 1,3-pentanediamine.

[0016] Preferably, after the first reaction is completed, the method further comprises:

[0017] The obtained product is filtered, washed and dried to obtain a reaction product;

[0018] After the second reaction is completed, it is preferred that the following further comprises:

[0019] The obtained reaction product is subjected to reduced pressure distillation to obtain a spiro polyamide epoxy resin curing agent.

[0020] Preferably, the preparation method of the spiro polyamide epoxy resin curing agent specifically includes:

[0021] Adding diacryl acetal pentaerythritol, a carboxyl-containing thiol compound and methanol to a reactor, stirring evenly, then adding a free radical initiator to disperse evenly, heating to 50-70° C. under nitrogen protection, starting a thiol-vinyl addition reaction, and reacting for 3-6 hours. After the reaction is completed, filtering and washing three times with methanol, and drying under vacuum at 50° C. overnight to obtain a reaction intermediate product, i.e., a spiroacetal compound containing a terminal dicarboxyl group;

[0022] The spiroacetal compound containing terminal dicarboxyl groups and an aliphatic diamine are added to a reactor with toluene as the solvent. The mixture is reacted at 50° C. for 1 hour under nitrogen protection and then heated to 125-135° C. to continue the reaction. The reaction is stopped when no water appears in the water remover. The obtained polyamide is subjected to reduced pressure distillation at 80-100° C. to remove the solvent and by-products, thereby obtaining a spiro polyamide epoxy resin curing agent.

[0023] The present invention provides a spiro polyamide epoxy resin curing agent prepared by the method described in the above technical solution, wherein the number average molecular weight of the spiro polyamide epoxy resin curing agent is 1000-3000.

[0024] The present invention provides a cured product, which is prepared from the spiro polyamide epoxy resin curing agent prepared by the method described in the above technical solution, or the material of the spiro polyamide epoxy resin curing agent described in the above technical solution.

[0025] The present invention has discovered that polyamides synthesized using a spirocyclic aliphatic diamine as a precursor and the resulting cured materials as a curing agent exhibit superior performance. The present invention has designed a novel spirocyclic polyamide as an epoxy resin curing agent to address the shortcomings of epoxy resins, particularly improving the toughness and adhesion of the cured product. The present invention provides a spirocyclic polyamide epoxy resin curing agent and a preparation method thereof. A terminal dicarboxyl group-containing compound is synthesized using a thiol-ene click reaction, which is then polycondensed with an aliphatic diamine to yield a spirocyclic polyamide epoxy resin curing agent.

[0026] This invention provides a method for preparing a novel epoxy resin curing agent. A dicarboxyl-terminated compound is synthesized through a thiol-ene click reaction, which is then polycondensed with ethylenediamine to produce a polyamide containing a spirocyclic structure. Compared to existing polyamide curing agents, the spirocyclic and sulfide bond structures of this curing agent enhance the toughness of the cured product. It also possesses the advantages of polyamide curing agents, such as room-temperature curing and high adhesion of the cured product. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a photograph of the dicarboxyl-terminated spiroacetal compound prepared in Example 1;

[0028] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the dicarboxyl-terminated spiroacetal compound prepared in Example 1;

[0029] Figure 3 This is a photo of the spiro polyamide epoxy resin curing agent prepared in Example 1;

[0030] Figure 4 This is the H NMR spectrum of the spiro polyamide epoxy resin curing agent prepared in Example 1;

[0031] Figure 5 This is a picture of the cured sample prepared in Example 1;

[0032] Figure 6This is a bending comparison diagram of the spiro polyamide epoxy resin cured product prepared in Example 1 and the traditional acid anhydride epoxy resin cured product at 80°C;

[0033] Figure 7 This is a T-peel strength graph of a conventional acid anhydride pure epoxy resin cured product, a conventional acid anhydride epoxy resin cured product with added silicon powder, and a spiro polyamide epoxy resin cured product prepared in Example 2 at room temperature;

[0034] Figure 8 This is a V-notch impact strength test chart of traditional acid anhydride pure epoxy resin cured product, traditional acid anhydride added silicon powder epoxy resin cured product, commercial polyamide 650 cured product and the spiro polyamide epoxy resin cured product prepared in Example 2 at room temperature. DETAILED DESCRIPTION

[0035] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] The present invention provides a method for preparing a spiro polyamide epoxy resin curing agent, comprising:

[0037] Under the action of an initiator, diacryl acetal pentaerythritol and a carboxyl-containing thiol compound are subjected to a first reaction in methanol to obtain a reaction intermediate product;

[0038] The reaction intermediate product and aliphatic diamine are subjected to a second reaction in a solvent to obtain a spiro polyamide epoxy resin curing agent.

[0039] In the present invention, the initiator is preferably a free radical initiator, more preferably one or more selected from dibenzoyl peroxide, dodecyl peroxide, dicyclohexyl peroxydicarbonate, azobisisobutyronitrile, azobisisoheptylnitrile, methyl vinyl ketone, benzoin, benzoin dimethyl ether, benzophenone or eosin.

[0040] In the present invention, the carboxyl-containing thiol compound is preferably a monothiol compound, more preferably one or more selected from 2-mercaptopropionic acid, 3-mercaptopropionic acid, 4-mercaptobutyric acid, 3-mercaptoisobutyric acid, 5-mercaptovaleric acid, and 6-mercaptohexanoic acid.

[0041] In the present invention, the usage ratio of the initiator, diacryl pentaerythritol acetal, carboxyl-containing thiol compound and methanol is preferably (0.8-1.2) mmol: (22-25) mmol: (68-72) mmol: (3-5) mL, more preferably (0.9-1.1) mmol: (23-24) mmol: (69-71) mmol: (3.5-4.5) mL, and most preferably 1.0 mmol: 23.5 mmol: 70 mmol: 4 mL.

[0042] In the present invention, the first reaction is preferably carried out under the protection of nitrogen; the temperature of the first reaction is preferably 50-70°C, more preferably 55-65°C, and most preferably 60°C; the time of the first reaction is preferably 3-6 hours, more preferably 4-5 hours.

[0043] In the present invention, after the first reaction is completed, it is preferred that the following steps are further included:

[0044] The obtained product is filtered, washed and dried to obtain a spiroacetal compound containing a terminal dicarboxyl group (reaction intermediate product).

[0045] In the present invention, the filtration is preferably suction filtration; the washing is preferably washing with methanol; the number of washings is preferably 2 to 4 times, more preferably 3 times; the drying is preferably vacuum drying; the drying temperature is preferably 40 to 60°C, more preferably 45 to 55°C, and most preferably 50°C.

[0046] In the present invention, the aliphatic diamine is preferably selected from one or more of ethylenediamine, propylenediamine, pentanediamine, hexamethylenediamine, 1,2-cycloethylenediamine, 2-methylpentanediamine and 1,3-pentanediamine.

[0047] In the present invention, the solvent in the second reaction is preferably toluene.

[0048] In the present invention, the molar ratio of the diacrolein pentaerythritol acetal to the aliphatic diamine is preferably (1-3): (2-6), more preferably (1.5-2.5): (3-5), and most preferably 2:4.

[0049] In the present invention, the second reaction is preferably carried out under the protection of nitrogen.

[0050] In the present invention, the method of the second reaction preferably comprises:

[0051] The reaction is first carried out at a first temperature and then the temperature is raised to a second temperature to continue the reaction.

[0052] In the present invention, the first temperature is preferably 45-55°C, more preferably 48-52°C, and most preferably 50°C; the reaction time at the first temperature is preferably 0.5-1.5 hours, more preferably 0.8-1.2 hours, and most preferably 1.0 hour; the second temperature is preferably 125-135°C, more preferably 128-132°C, and most preferably 130°C; the reaction at the second temperature is preferably stopped when no water appears; the reaction time at the second temperature is preferably 1-2 hours, more preferably 1.5 hours.

[0053] In the present invention, after the second reaction is completed, it is preferred that the following further comprises:

[0054] The obtained reaction product is subjected to reduced pressure distillation to remove the solvent and by-products to obtain a spiro polyamide epoxy resin curing agent.

[0055] In the present invention, the temperature of the reduced pressure distillation is preferably 80-100°C, more preferably 85-95°C, and most preferably 90°C.

[0056] In the present invention, the preparation method of the spiro polyamide epoxy resin curing agent preferably includes:

[0057] Adding diacryl acetal pentaerythritol, a carboxyl-containing thiol compound and methanol into a reactor and stirring evenly, then adding a free radical initiator and dispersing evenly, heating to 50-70° C. under nitrogen protection, starting a thiol-vinyl addition reaction, and reacting for 3-6 hours. After the reaction is completed, filtering and washing three times with methanol, and drying under vacuum at 50° C. overnight to obtain a spiroacetal compound containing a terminal dicarboxyl group;

[0058] The obtained spiroacetal compound containing terminal dicarboxyl groups and aliphatic diamine are added to a reactor in a certain proportion, with toluene as the solvent. The reaction is carried out at 50°C for 1 hour under nitrogen protection and then the temperature is raised to 125-135°C to continue the reaction. The reaction is stopped when no water appears in the dehydrator (1-2 hours). The obtained polyamide is distilled under reduced pressure at 80-100°C to remove the solvent and by-products, thereby obtaining a spiro polyamide epoxy resin curing agent.

[0059] The present invention provides a cured product, which is prepared from the spiro polyamide epoxy resin curing agent prepared by the method described in the above technical solution, or the material of the spiro polyamide epoxy resin curing agent described in the above technical solution.

[0060] In the present invention, the method for preparing the cured product preferably comprises:

[0061] The epoxy resin and the spirocyclic polyamide epoxy resin curing agent are mixed and then cured to obtain a cured product.

[0062] In the present invention, the epoxy resin is preferably E-51 epoxy resin; the mass ratio of the epoxy resin to the spiropolyamide epoxy resin curing agent is preferably (1-3):1, more preferably (1.5-2.5):1, and most preferably 2:1. In the present invention, the mixture is preferably uniformly mixed and poured into a mold; the curing is preferably carried out in a vacuum drying oven; the curing temperature is preferably 20-40°C, more preferably 25-35°C, and most preferably 25°C; the curing time is preferably 16-36 hours, more preferably 18-30 hours, and most preferably 24 hours; and after curing, the mixture is preferably cooled naturally to room temperature.

[0063] This invention designs a novel polyamide containing a spirocyclic structure as an epoxy resin curing agent to improve the shortcomings of epoxy resin. A spirocyclic polyamide epoxy resin curing agent and its preparation method are provided. A compound containing terminal dicarboxyl groups is synthesized through a thiol-vinyl click reaction, which is then polycondensed with an aliphatic diamine to produce the spirocyclic polyamide epoxy resin curing agent.

[0064] The diacryl pentaerythritol used in the following examples of the present invention was purchased from Aladdin Company, with the product number: D139272, and the purity was ≥98.0% (GC).

[0065] Example 1

[0066] 23.6mmol of dipropylene spiroacetal pentaerythritol, 70.8mmol of mercaptopropionic acid and 3mL of methanol were added to the reactor and stirred evenly. Then, 1.2mmol of free radical initiator azobisisobutyronitrile (AIBN) was added and dispersed evenly. The temperature was raised to 60°C under nitrogen protection to start the mercapto-vinyl addition reaction. The reaction time was 5 hours. After the reaction was completed, the mixture was filtered and washed three times with methanol, and then dried under vacuum at 50°C overnight to obtain a compound. The dried compound was as shown in FIG. Figure 1 Its H NMR spectrum is shown as Figure 2 As shown, from Figure 2 It can be confirmed that the dicarboxyl-terminated spiroacetal compound was successfully synthesized.

[0067] The dicarboxyl-terminated spiroacetal compound obtained above and ethylenediamine were added to the reactor at a molar ratio of 1:2, with toluene as the solvent. The reaction was carried out at 50°C for 1 hour under nitrogen protection, and then the temperature was raised to 130°C to continue the reaction. When no water appeared in the water remover, the reaction was stopped (1 to 2 hours). The obtained polyamide was distilled under reduced pressure at 90°C to remove the solvent and by-products, and a spiro polyamide epoxy resin curing agent was obtained, such as Figure 3 As shown, from Figure 4 The successful synthesis of this curing agent can be confirmed from the H NMR spectrum.

[0068] In parts by weight, 10 parts of E-51 epoxy resin and 5 parts of the spiro polyamide epoxy resin curing agent prepared above were mixed evenly and poured into a mold. The mixture was cured at room temperature for 24 hours. The sample obtained after curing was light yellow and transparent. Figure 5 shown.

[0069] Comparing the bending of the sample cured with the spiro polyamide epoxy resin curing agent and the sample cured with the traditional curing agent (methyltetrahydrophthalic anhydride) at 80°C, it can be clearly seen that the sample cured with the spiro polyamide epoxy resin curing agent has better toughness and can be bent well. Figure 6 As shown in the left figure; the sample cured by methyltetrahydrophthalic anhydride breaks after bending, as shown in the figure on the left. Figure 6 As shown in the picture on the right.

[0070] In parts by weight, 10 parts of E-51 epoxy resin and 5 parts of the spiro polyamide epoxy resin curing agent prepared above were mixed evenly, poured into a mold, and cured at room temperature for 24 hours. The samples cured with a traditional curing agent (methyltetrahydrophthalic anhydride), a traditional curing agent and silica powder (the mass of silica powder accounts for 60% of the total mass of silica powder, epoxy resin and curing agent), and polyamide 650 as a curing agent were compared in T peel strength (GB / T 2791-1995 Adhesive T peel strength test method flexible material to flexible material) and V-notch impact strength test (GB / T2571-1995 Resin casting impact test method). From the T peel strength, it can be seen that the T peel strength of the traditional acid anhydride cured product with silica powder is 32.7N / 25mm, while the T peel strength of the sample cured with the spiro polyamide epoxy resin curing agent is 41.5N / 25mm. Figure 7 As shown in the figure, it can be clearly seen that the strength of the sample cured with the addition of silicon powder is much higher than that of the sample cured with pure epoxy resin. In addition, compared with the cured product of the present invention, it can be clearly seen that the impact strength of the sample cured with the cyclic polyamide epoxy resin curing agent is twice as high as that of the epoxy resin cured product with the addition of silicon powder. Figure 8 shown.

[0071] This invention designs a novel polyamide containing a spirocyclic structure as an epoxy resin curing agent to improve the shortcomings of epoxy resins, particularly the toughness and adhesion of the cured product. A spirocyclic polyamide epoxy resin curing agent and its preparation method are provided. A compound containing terminal dicarboxyl groups is synthesized through a thiol-vinyl click reaction, which is then polycondensed with an aliphatic diamine to produce the spirocyclic polyamide epoxy resin curing agent.

[0072] Although the present invention has been described and illustrated with reference to specific embodiments of the present invention, these descriptions and illustrations do not limit the present invention. It will be clearly understood by those skilled in the art that, without departing from the true spirit and scope of the present invention as defined by the appended claims, various changes may be made to make specific circumstances, materials, compositions of matter, substances, methods or processes suitable for the object, spirit and scope of the present application. All such modifications are intended to be within the scope of the appended claims. Although the methods disclosed herein have been described with reference to specific operations performed in a specific order, it will be understood that these operations may be combined, subdivided or reordered to form equivalent methods without departing from the teachings of the present invention. Therefore, unless otherwise indicated herein, the order and grouping of operations are not limitations of the present application.

Claims

1. A method for preparing a spiro polyamide epoxy resin curing agent, comprising: Under the action of an initiator, acrolein pentaerythritol acetal and a carboxyl-containing thiol compound are subjected to a first reaction in methanol to obtain a reaction intermediate product; the carboxyl-containing thiol compound is a monothiol compound selected from one or more of 2-mercaptopropionic acid, 3-mercaptopropionic acid, 4-mercaptobutyric acid, 3-mercaptoisobutyric acid, 5-mercaptovaleric acid, and 6-mercaptohexanoic acid; the first reaction is a thiol-vinyl addition reaction; and the reaction intermediate product is a compound containing a terminal dicarboxyl group; The reaction intermediate product and an aliphatic diamine are subjected to a second reaction in a solvent to obtain a spiropolyamide epoxy resin curing agent; the aliphatic diamine is selected from one or more of ethylenediamine, propylenediamine, pentamethylenediamine, hexamethylenediamine, 1,2-ethylenediamine and 2-methylpentamethylenediamine; and the second reaction is a polycondensation reaction; The ratio of the initiator, diacrolein pentaerythritol acetal, carboxyl-containing thiol compound and methanol is (0.8-1.2) mmol: (22-25) mmol: (68-72) mmol: (3-5) mL; The molar ratio of the diacryl pentaerythritol acetal to the aliphatic diamine is (1-3): (2-6); The number average molecular weight of the spiro polyamide epoxy resin curing agent is 1000-3000.

2. The method according to claim 1, characterized in that The first reaction is carried out under the protection of nitrogen; The temperature of the first reaction is 50-70° C., and the time is 3-6 hours.

3. The method according to claim 1, characterized in that The second reaction comprises: First react at a first temperature and then raise the temperature to a second temperature to continue the reaction; The first temperature is 45-55°C, and the second temperature is 125-135°C.

4. The method according to claim 1, wherein The initiator is a free radical initiator, selected from one of dibenzoyl peroxide, dodecyl peroxide, dicyclohexyl peroxydicarbonate, azobisisobutyronitrile, azobisisoheptylnitrile, methyl vinyl ketone, benzoin, benzoin dimethyl ether, benzophenone or eosin.

5. The method according to claim 1, wherein After the first reaction is completed, the following steps are further included: The obtained product is filtered, washed and dried to obtain a reaction product; After the second reaction is completed, the following steps are also included: The obtained reaction product is subjected to reduced pressure distillation to obtain a spiro polyamide epoxy resin curing agent.

6. The method according to claim 1, characterized in that The preparation method of the spiro polyamide epoxy resin curing agent specifically includes: Adding diacryl acetal pentaerythritol, a carboxyl-containing thiol compound and methanol to a reactor and stirring evenly, then adding a free radical initiator and dispersing evenly, heating to 50-70° C. under nitrogen protection, starting a thiol-vinyl addition reaction, and reacting for 3-6 hours. After the reaction is completed, filtering and washing three times with methanol, and drying under vacuum at 50° C. overnight to obtain a reaction intermediate product, i.e., a spiroacetal compound containing a terminal dicarboxyl group; The spiroacetal compound containing terminal dicarboxyl groups and an aliphatic diamine are added to a reactor with toluene as the solvent. The mixture is reacted at 50° C. for 1 hour under nitrogen protection and then heated to 125-135° C. to continue the reaction. The reaction is stopped when no water appears in the water remover. The obtained polyamide is subjected to reduced pressure distillation at 80-100° C. to remove the solvent and by-products, thereby obtaining a spiro polyamide epoxy resin curing agent.

7. A spiro polyamide epoxy resin curing agent prepared by the method according to claim 1, wherein the number average molecular weight of the spiro polyamide epoxy resin curing agent is 1000-3000.

8. A cured product prepared from a material comprising the spiro polyamide epoxy resin curing agent prepared by the method of claim 1 or the spiro polyamide epoxy resin curing agent of claim 7.

Images