Acid anhydride cured epoxy resin composition for pouring process and preparation method thereof

Abstract

The invention relates to the technical field of coatings, in particular to an anhydride cured epoxy resin composition for a pouring process and a preparation method of the anhydride cured epoxy resin composition. The anhydride cured epoxy resin composition for the pouring process comprises a component A and a component B, wherein the component A comprises liquid epoxy resin and a reactive diluent; the weight ratio of the liquid epoxy resin to the reactive diluent is (70-90): (10-30); the component B comprises an anhydride curing agent, a toughening agent, a first accelerant and a second accelerant; the first accelerant is a quaternary ammonium salt accelerant, and the second accelerant is an amine accelerant. The anhydride cured epoxy resin composition for the pouring process provided by the invention can be cured in a short period under medium and low temperature conditions, and a cured product can achieve good mechanical properties, has good tensile and bending properties, and has a better application prospect compared with the existing amine curing agent system epoxy resin cured under the same conditions. Wherein the elongation at break after low-temperature short-period curing is improved.

Description

Technical Field

[0001] The present application relates to the technical field of epoxy resins for infusion, and in particular to an anhydride-cured epoxy resin composition for infusion process and a preparation method thereof. Background Art

[0002] The epoxy resin vacuum infusion system is a composite system composed of epoxy resin and curing agent system. At present, amines are generally used as curing agents in epoxy resin compositions for vacuum infusion.

[0003] Compared with anhydride epoxy resins, amine epoxy resins have lower curing temperatures. Anhydride epoxy resins generally require high temperature curing, which is much higher than the curing temperature of amine curing agents.

[0004] Since the cost of anhydride curing system is lower than that of amine curing system, how to achieve medium and low temperature curing of anhydride curing system is one of the research directions in this field. That is, medium and low temperature curing of anhydride system epoxy resin has become a research direction in this field. However, the existing anhydride system epoxy resin that can be cured at medium and low temperatures has a longer curing time, although the curing temperature is reduced. If the curing time is insufficient, the tensile elongation at break is low. For example: The Chinese invention patent application with publication number CN114806087A and publication date July 29, 2022, discloses an epoxy resin-anhydride system for vacuum infusion wind turbine blades and its preparation method. The product of this solution uses anhydride as a curing agent for curing at a medium temperature of 60-100°C. The specific curing temperature and curing time are not specified. The elongation at break is 6.3%-7.1%, which is lower than 17.6% of the amine system cured under the same conditions.

[0005] In summary, how to achieve the curing of anhydride-based epoxy resin that can be cured at medium and low temperatures in a short curing cycle so that it has good mechanical properties (good elongation at break) is the technical problem that this field is committed to solving. Summary of the invention

[0006] In order to solve the problems of the prior art mentioned in the above background technology, the present application provides an anhydride-cured epoxy resin composition for a perfusion process, and its technical solution is as follows: The present application provides an anhydride-cured epoxy resin composition for an infusion process, which comprises a component A and a component B, wherein the component A comprises a liquid epoxy resin and a reactive diluent; wherein the weight ratio of the liquid epoxy resin to the reactive diluent is (70-90):(10-30); the component B comprises an anhydride curing agent, a toughening agent, a first accelerator and a second accelerator; wherein the first accelerator is a quaternary ammonium salt accelerator, and the second accelerator is an amine accelerator; the weight ratio of the anhydride curing agent, the toughening agent, the first accelerator and the second accelerator is (60-85):(8-35):(1-6):(0.3-1).

[0007] In some embodiments, the component A comprises, by weight: 70 to 90 parts of liquid epoxy resin, 10 to 30 parts of reactive diluent, and 0 to 1 part of auxiliary agent; the component B comprises, by weight: 60 to 85 parts of anhydride curing agent, 8 to 35 parts of toughening agent, 1 to 6 parts of first accelerator, and 0.3 to 1 part of second accelerator; the weight ratio of the component A to the component B is 100:(90 to 110).

[0008] In some embodiments, the first accelerator is a quaternary ammonium salt accelerator, which is one or more combinations of benzyltrimethylammonium chloride and benzyltriethylammonium chloride; preferably, the first accelerator is benzyltriethylammonium chloride. The second accelerator is an amine accelerator, which is one or more combinations of N,N-dimethylbenzylamine and N,N-diethylethylamine.

[0009] In some embodiments, the liquid epoxy resin is one or a combination of E54 and E51; the reactive diluent is one or a combination of carbon dodecadecyl glycidyl ether and 1,4-butanediol diglycidyl ether. Preferably, the reactive diluent is 1,4-butanediol diglycidyl ether.

[0010] In some embodiments, the auxiliary agent is a polysiloxane defoamer; for example, BYKA530 or BYK088 may be selected.

[0011] In some embodiments, the anhydride curing agent is one or a combination of methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride.

[0012] In some embodiments, the toughening agent is a polyether polyol with a characteristic molecular weight of 400 to 1000. Optionally, the toughening agent is one or a combination of DDL-1000 and DDL-400. Preferably, the polyether polyol is DDL-1000.

[0013] The present application also provides a method for preparing the anhydride-cured epoxy resin composition for the infusion process as described above, which comprises the following steps: According to the formula of component A, epoxy resin, active diluent and auxiliary agent are weighed and placed in a reactor, stirring is started and the material system is heated to (50-60)°C. After the materials are evenly dispersed, the material system is cooled to room temperature to obtain the component A; According to the formula of component B, an anhydride curing agent and a first accelerator are weighed and placed in a reactor, stirring is started and the material system is heated to (70-80)°C; then a toughening agent is added, and the mixture is dispersed at 70-80°C for (50-60) minutes; then a second accelerator is added, and the mixture is dispersed at 70-80°C for (20-40) minutes, and the material system is cooled to room temperature to obtain the component B; According to the formula, component A and component B are mixed evenly to obtain the anhydride-cured epoxy resin composition for the infusion process.

[0014] Compared with the prior art, the anhydride-cured epoxy resin composition for the infusion process provided in the present application has the following beneficial effects: In the anhydride-cured epoxy resin composition for the infusion process provided by the present application, a polyether polyol-modified anhydride curing agent is added to increase toughness, and a quaternary ammonium salt and an amine accelerator are added for synergistic effect, which significantly reduces the curing temperature and curing time of the anhydride system epoxy resin and shortens the glass fiber composite manufacturing cycle. In addition, the tensile strength and modulus, bending strength and modulus of the anhydride-cured epoxy resin composition system for the infusion process are better than those of the amine curing agent system epoxy resin, and the tensile elongation at break is also better than that of the amine curing agent system epoxy resin cured under the same conditions.

[0015] In summary, the present application provides an anhydride-cured epoxy resin composition for an infusion process, which can be cured in a short period of time under medium and low temperature conditions. The cured product can achieve good mechanical properties and has good tensile and bending properties. Compared with the existing amine curing agent system epoxy resin cured under the same conditions, the elongation at break after low temperature and short period of curing is improved. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0017] The present application provides an example of the preparation process of an anhydride-cured epoxy resin composition for a perfusion process as follows: (1) According to the formula of component A, epoxy resin, active diluent and auxiliary agent are weighed and placed in a reactor, stirring is started and the material system is heated to (50-60)°C. After the materials are evenly dispersed, the material system is cooled to room temperature to obtain the component A; (2) According to the formula of component B, an anhydride curing agent and a first accelerator are weighed and placed in a reactor, stirring is started and the material system is heated to (70-80)°C; then a toughening agent is added, and the mixture is dispersed at 70-80°C for (50-60) min; then a second accelerator is added, and the mixture is dispersed at 70-80°C for (20-40) min, and the material system is cooled to room temperature to obtain the component B; (3) According to the formula, component A and component B are mixed evenly to obtain the anhydride-cured epoxy resin composition for the infusion process.

[0018] Among them, the formula of the anhydride-cured epoxy resin composition for the infusion process is as follows: In parts by weight, component A includes: 70-90 parts of liquid epoxy resin, 10-30 parts of active diluent, and 0-1 part of auxiliary agent; component B includes: 60-85 parts of anhydride curing agent, 8-35 parts of toughening agent, 1-6 parts of first accelerator, and 0.3-1 part of second accelerator; wherein the weight ratio of component A to component B is 100:(90-110).

[0019] For each raw material component selection: The liquid epoxy resin used is one of E54 and E51 or a combination of the two; The active diluent used is one or a combination of carbonyl dodecadecyl glycidyl ether and 1,4-butanediol diglycidyl ether. Preferably, the active diluent is 1,4-butanediol diglycidyl ether.

[0020] The auxiliary agent used is a polysiloxane defoamer, such as BYKA530 or BYK088.

[0021] The acid anhydride curing agent used is one or a combination of methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride; The toughening agent used is a polyether polyol with a characteristic molecular weight of 400 to 1000. Optionally, the toughening agent is one of DDL-1000 and DDL-400 or a combination of the two. Preferably, the polyether polyol is DDL-1000.

[0022] The first accelerator used is a quaternary ammonium salt accelerator, which is a combination of one or more of benzyltrimethylammonium chloride and benzyltriethylammonium chloride; preferably, the first accelerator is benzyltriethylammonium chloride.

[0023] The second accelerator used is an amine accelerator, which is one or more combinations of N,N-dimethylbenzylamine and N,N-diethylethylamine.

[0024] The present application also provides the following examples and comparative example 1: The formulas of Examples 1-6 and Comparative Example 2 of the present application are shown in Table 1: Table 1 Formula (unit, parts by weight)

[0025] Comparative Example 1 uses a commercially available amine-curing system epoxy resin, wherein the mass ratio of component A to component B is 100:28.

[0026] Comparative Example 2 is based on Example 1, except that only the proportion of the accelerator is adjusted, and other raw material selections, preparation steps and conditions are consistent with those of Example 1.

[0027] Wherein, the preparation methods of Comparative Example 1 and the embodiment are as follows: Step 1: Prepare component A Weigh epoxy resin, active diluent and auxiliary agent according to weight proportions respectively and place them in a three-necked flask, start stirring, and heat to 50°C. After dispersing evenly, cool to room temperature to obtain component A; Step 2: Prepare component B According to the weight proportions, the anhydride curing agent and the first accelerator were weighed and placed in a three-necked flask. Stirring was started and the mixture was heated to 75°C. Then the toughening agent was added and the mixture was dispersed at 75°C for 60 minutes. Then the second accelerator was added and the mixture was dispersed at 75°C for 30 minutes. The mixture was cooled to room temperature to obtain component B.

[0028] Step 3: Preparation of epoxy resin composition According to the weight percentage, the component A and the component B are mixed evenly in proportion to obtain the anhydride-cured epoxy resin composition for the infusion process.

[0029] The embodiments and comparative examples were tested: The test methods were performed according to the relevant test standards: The epoxy resin composition for infusion process prepared in the embodiment and the comparative example was used to prepare a pure epoxy resin material (ER) and an epoxy resin composite material containing glass fiber (GF-ER) was prepared by infusion molding; and the mechanical properties of the two materials were tested; three samples were taken for each material, and each sample was tested 6 times, and the results were averaged; Among them, ISO527, ISO178 and ISO11357-2 were used to test the tensile, bending and glass transition temperature of pure epoxy resin materials; ISO 527, ISO 14125 and ISO 14126 were used to test the tensile, bending and compression properties of epoxy resin composites of uniaxial UDS1250 glass fiber fabric prepared by infusion molding. The results are shown in Table 2 (mechanical properties of pure epoxy resin materials) and Table 3 (mechanical properties of epoxy resin composites containing glass fibers); The preparation method of pure epoxy resin material is as follows: casting the anhydride-cured epoxy resin composition for infusion process prepared in each embodiment and comparative example into a mold, curing at 70° C. for 4 hours; and cutting into standard test pieces after demoulding for performance testing.

[0030] The preparation method of the glass fiber-containing epoxy resin composite material is as follows: the composition prepared in each embodiment and comparative example is matched with uniaxial UDS1250 glass fiber fabric by infusion process to prepare the epoxy resin composite material. The curing process is 70° C. heat preservation and curing for 3 hours.

[0031] 1. The mechanical properties of pure epoxy resin materials were tested, and the results are shown in Table 2 below: Table 2 Test items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Tensile strength, MPa 74.2 75.5 74.1 74.2 75.1 75.3 69.5 64.5 Tensile modulus, GPa 3.12 3.25 3.23 3.11 3.32 3.32 3.08 2.71 Elongation at break, % 10.2 9.5 10.9 9.6 10.5 9.7 7.8 3.2 Bending strength, MPa 122.8 123.4 124.5 126.4 124.2 128.5 123.2 103.2 Flexural modulus, GPa 3.11 3.35 3.25 3.31 3.31 3.22 3.02 2.68 Glass transition temperature, °C 85 86 89 83 87 86 76 68 2. The mechanical properties of the epoxy resin composite material containing glass fiber were tested, and the results are shown in Table 3 below: Table 3 Test items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Tensile strength, MPa 1142.8 1134.2 1145.1 1138.4 1136.8 1137.7 1009.2 948.2 Tensile modulus, GPa 66.2 67.1 66.3 66.8 67.5 67.1 65.1 58.2 Bending strength, MPa 1070.2 1050.8 1061.4 1050.2 1041.2 1062.7 998.1 892.1 Flexural modulus, GPa 59.4 58.8 60.7 59.8 59.6 61.7 58.7 52.2 Compression strength, MPa 1021.3 1031.8 1022.4 1021.6 1032.3 1013.1 988.9 872.1 Compression modulus, GPa 66.5 65.6 66.7 65.8 67.4 66.8 65.1 58.6 Analyzing the above data, we can see that: In the anhydride-cured epoxy resin composition for the infusion process provided in the embodiment of the present application, a polyether polyol-modified anhydride curing agent is added to increase toughness, and a quaternary ammonium salt and an amine accelerator are added for synergistic effect, which significantly reduces the curing temperature and curing time of the anhydride system epoxy resin, and can be cured within 3 hours at 70°C, shortening the glass fiber composite manufacturing cycle. In addition, the tensile strength and modulus, bending strength and modulus of the anhydride-cured epoxy resin composition system for the infusion process are better than those of the amine curing agent system epoxy resin, and the tensile elongation at break can reach more than 9%, and the tensile elongation at break is also better than the amine curing agent system epoxy resin cured under the same conditions.

[0032] In summary, the present application provides an anhydride-cured epoxy resin composition for an infusion process, which can be cured in a short period of time under medium and low temperature conditions. The cured product can achieve good mechanical properties and has good tensile and bending properties. Compared with the existing amine curing agent system epoxy resin cured under the same conditions, the elongation at break after low temperature and short period of curing is improved.

[0033] It should be noted that: In this article, “~” is used to indicate a numerical range, and the range indicated by this expression includes two endpoint values.

[0034] In addition to the actual selections embodied in the above specific embodiments, the above formulation ranges may be used in the specific implementation of the present application, including but not limited to the above embodiment schemes.

[0035] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments of the present application, but are not intended to limit the present application. Those skilled in the art may make adaptive adjustments within the scope of the present application.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An anhydride-cured epoxy resin composition for a perfusion process, comprising a component A and a component B, characterized in that: The component A comprises liquid epoxy resin and reactive diluent; Wherein, the weight ratio of the liquid epoxy resin to the reactive diluent is (70-90): (10-30); The component B includes an anhydride curing agent, a toughening agent, a first accelerator and a second accelerator; Among them, the first accelerator is a quaternary ammonium salt accelerator, and the second accelerator is an amine accelerator; the weight ratio of the anhydride curing agent, the toughening agent, the first accelerator and the second accelerator is (60-85): (8-35): (1-6): (0.3-1).

2. The anhydride-cured epoxy resin composition for infusion process according to claim 1, characterized in that: In parts by weight, the component A comprises: 70-90 parts of liquid epoxy resin, 10-30 parts of reactive diluent, and 0-1 part of auxiliary agent; In parts by weight, the component B includes: 60 to 85 parts of anhydride curing agent, 8 to 35 parts of toughening agent, 1 to 6 parts of first accelerator, and 0.3 to 1 part of second accelerator; The weight ratio of the component A to the component B is 100:(90-110).

3. The anhydride-cured epoxy resin composition for infusion process according to claim 1, characterized in that: The first accelerator is a quaternary ammonium salt accelerator, which is one or more combinations of benzyltrimethylammonium chloride and benzyltriethylammonium chloride; The second accelerator is an amine accelerator, which is one or more combinations of N,N-dimethylbenzylamine and N,N-diethylethylamine.

4. The anhydride-cured epoxy resin composition for infusion process according to claim 3, characterized in that: The first accelerator is benzyltriethylammonium chloride.

5. The anhydride-cured epoxy resin composition for infusion process according to claim 1, characterized in that: The liquid epoxy resin is one or a combination of E54 and E51; The active diluent is one or a combination of two of dodecanediol glycidyl ether and 1,4-butanediol diglycidyl ether.

6. The anhydride-cured epoxy resin composition for infusion process according to claim 5, characterized in that: The active diluent is 1,4-butanediol diglycidyl ether.

7. The anhydride-cured epoxy resin composition for infusion process according to claim 2, characterized in that: The auxiliary agent is a polysiloxane defoamer.

8. The anhydride-cured epoxy resin composition for infusion process according to claim 1, characterized in that: The acid anhydride curing agent is one or a combination of methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride; The toughening agent is a polyether polyol, Its characteristic molecular weight is 400-1000.

9. The anhydride-cured epoxy resin composition for infusion process according to claim 1, characterized in that: The toughening agent is one of DDL-1000 and DDL-400 or a combination of the two.

10. A method for preparing the anhydride-cured epoxy resin composition for infusion process according to any one of claims 1 to 9, characterized in that: The following steps are included According to the formula of component A, epoxy resin, active diluent and auxiliary agent are weighed and placed in a reactor, stirring is started and the material system is heated to (50-60)°C. After the materials are evenly dispersed, the material system is cooled to room temperature to obtain the component A; According to the formula of component B, an anhydride curing agent and a first accelerator are weighed and placed in a reactor, stirring is started and the material system is heated to (70-80)°C; then a toughening agent is added, and the mixture is dispersed at 70-80°C for (50-60) minutes; then a second accelerator is added, and the mixture is dispersed at 70-80°C for (20-40) minutes, and the material system is cooled to room temperature to obtain the component B; According to the formula, component A and component B are mixed evenly to obtain the anhydride-cured epoxy resin composition for the infusion process.

Images