Thermosetting resin and preparation method thereof

Abstract

The invention discloses a thermosetting resin and a preparation method thereof. The preparation method comprises the following steps: (1) respectively preparing a prepolymerization solution of a monomer I and a prepolymerization solution of a monomer II; the monomer I is formed by mixing dicyclopentadiene and ethylidene norbornene; the monomer II is formed by mixing dicyclopentadiene and cyclooctene; (2) under a heating condition, preparing a laminated material formed by precuring a prepolymerization solution of a monomer I and a prepolymerization solution of a monomer II; and (3) carrying out heat treatment on the laminated material obtained in the step (2) to obtain the thermosetting resin. The layered thermosetting resin material with rigidity and toughness is constructed on the basis of a soft and hard combination multilayer strategy, dynamic carbon-carbon double bonds are contained between layers of the thermosetting resin, the interface action is enhanced through chemical bond dynamic exchange and physical swelling behaviors, and efficient toughening of the thermosetting resin is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of resin materials, and in particular to a thermosetting resin and a preparation method thereof. Background Art

[0002] Thermosetting materials and elastomers are two representative functional materials. The former have high cross-linking density, high glass transition temperature, high modulus, and high strength, and are often used as transportation and construction materials. However, thermosetting materials have poor macroscopic deformation ability and lack impact resistance, which severely limits their service life and is not conducive to industrial manufacturing. Elastomers usually exhibit low glass transition temperature and low modulus. When subjected to external forces, the movement of the molecular chain provides better resistance to deformation, and are widely used in wearable devices, shock-absorbing materials and other fields. How to balance the rigidity and flexibility of the material and construct a thermosetting material with a high-strength and high-toughness structure was not only an important cornerstone for promoting the development of aerospace, transportation facilities, national defense and other fields at the time, but also a frontier hotspot for interdisciplinary research in chemistry, mechanics and materials science. Summary of the invention

[0003] In view of the above technical problems, the purpose of the present invention is to provide a thermosetting resin and a preparation method thereof. The present invention toughens the thermosetting resin based on a soft-hard combination multilayer strategy to achieve both material rigidity and toughness, and utilizes the dynamic exchange of chemical bonds and physical swelling behavior to enhance the interface effect, thereby achieving efficient toughening of the thermosetting resin.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] In one aspect, the present invention provides a method for preparing a thermosetting resin, comprising the following steps:

[0006] (1) preparing prepolymer solutions of monomer I and monomer II respectively; the monomer I is a mixture of dicyclopentadiene and ethylidene norbornene; the monomer II is a mixture of dicyclopentadiene and cyclooctene;

[0007] (2) preparing a laminated material formed by pre-curing the pre-polymerized liquid of monomer I and the pre-polymerized liquid of monomer II under heating conditions;

[0008] (3) Heat-treating the laminated material obtained in step (2) to obtain a thermosetting resin.

[0009] In the technical solution of the present invention, the laminated material is a laminated material in which a single layer is overlapped or multiple layers are alternately overlapped after the prepolymerized liquid of monomer I and the prepolymerized liquid of monomer II are pre-cured.

[0010] As a preferred embodiment, in step (1), the prepolymer solution of monomer I is obtained by polymerizing monomer I under the action of a catalyst;

[0011] Preferably, the catalyst is selected from at least one of Grubbs second generation catalyst, Grubbs third generation catalyst, MgBr2 / TiCl4 and KiRuCl3·H2O;

[0012] Preferably, in the monomer I, the molar ratio of dicyclopentadiene to ethylidene norbornene is 1:0.05-1;

[0013] Preferably, the mass of the catalyst is 0.1% to 1% of the total mass of monomer I, more preferably 0.5%;

[0014] Preferably, the polymerization reaction temperature is 30 to 50°C;

[0015] Preferably, the polymerization reaction time is 5 to 10 minutes;

[0016] Preferably, the polymerization is carried out under stirring;

[0017] In some specific embodiments, the catalyst is added to the reaction system in the form of being dissolved in a trace amount of organic solvent, and the trace amount of organic solvent is volatilized during the subsequent pre-curing process to form the laminated material.

[0018] As a preferred embodiment, in step (1), the prepolymer solution of monomer II is obtained by polymerizing monomer II under the action of a catalyst;

[0019] Preferably, the catalyst is selected from at least one of Grubbs second generation catalyst, Grubbs third generation catalyst, MgBr2 / TiCl4 and KiRuCl3·H2O;

[0020] Preferably, in the monomer II, the molar ratio of dicyclopentadiene to cyclooctene is 1:0.25-1, more preferably 1:0.25-0.8;

[0021] Preferably, the mass of the catalyst is 0.1% to 1% of the total mass of monomer II, more preferably 0.5%;

[0022] Preferably, the polymerization reaction temperature is 30 to 50°C;

[0023] Preferably, the polymerization reaction time is 5 to 20 minutes;

[0024] Preferably, the polymerization is carried out under stirring;

[0025] In some specific embodiments, the catalyst is added to the reaction system in the form of being dissolved in a trace amount of organic solvent, and the trace amount of organic solvent is volatilized during the subsequent pre-curing process to form the laminated material.

[0026] As a preferred embodiment, in step (2), the heating temperature is 30 to 50° C., and the heating time is 5 to 20 minutes;

[0027] Preferably, the preparation process of the laminated material is as follows: ① under heating conditions, the prepolymer liquid of the monomer I and the prepolymer liquid of the monomer II are sequentially coated or alternately coated on the substrate for pre-curing to obtain the laminated material; or, ② the prepolymer liquid of the monomer I and the prepolymer liquid of the monomer II are sequentially injected or alternately injected into a mold, and pre-cured under heating conditions to obtain the laminated material;

[0028] Preferably, the coating is by scraping;

[0029] Preferably, in the sequential coating or sequential alternating coating, the coating mass ratio of the prepolymer solution of monomer I to the prepolymer solution of monomer II is 2-3:3-4;

[0030] Preferably, in the sequential injection or the sequential alternating injection, the injection mass ratio of the prepolymer solution of monomer I to the prepolymer solution of monomer II is 2-3:3-4;

[0031] In the technical solution of the present invention, a layered material with a low degree of cross-linking can be obtained by pre-curing under heating conditions.

[0032] As a preferred embodiment, in step (3), the heat treatment conditions are: temperature 80°C to 120°C, time 1 to 6 hours;

[0033] Preferably, the heat treatment is heating at 100°C for 3h;

[0034] In the technical solution of the present invention, further heat treatment can increase the crosslinking density of the material, thereby achieving a toughening effect.

[0035] In another aspect, the present invention provides a thermosetting resin obtained by the above preparation method.

[0036] The present invention has the following beneficial effects:

[0037] The present invention constructs a thermosetting resin material with both rigidity and toughness based on a soft-hard combination multilayer strategy. First, a multilayer material with a low crosslinking degree is prepared by sequentially scraping a prepolymer solution of a hard layer monomer / soft layer monomer or injecting a prepolymer solution of a hard layer monomer / soft layer monomer into a mold, and finally a multilayer toughened thermosetting resin with high toughness and strong impact resistance is obtained by heat treatment to increase the crosslinking degree. Among them, the hard layer is a polymerization product of monomer I (dicyclopentadiene and ethylidene norbornene), and the soft layer is a polymerization product of monomer II (dicyclopentadiene and cyclooctene).

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] 1. The reaction raw materials used in the present invention are easily available and have low viscosity, the preparation process is simple, the polymerization gelation time is short, the molding processing speed is fast, and the cost is low;

[0040] 2. The thermosetting resin provided by the present invention contains dynamic carbon-carbon double bonds between layers, and utilizes dynamic exchange of chemical bonds and physical swelling behavior to enhance the interfacial effect, thereby achieving efficient toughening of the thermosetting resin;

[0041] 3. The thermosetting resin provided by the present invention has excellent mechanical properties, mainly manifested in high rigidity and toughness, as well as excellent impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is the stress-strain curve of the thermosetting resin in Example 1 of the present invention;

[0043] Figure 2 This is a sample diagram of the thermosetting resin in Example 1 of the present invention;

[0044] Figure 3 is a scanning electron microscope image of the thermosetting resin in Example 1 of the present invention;

[0045] Figure 4 This is a ballistic penetration diagram of the thermosetting resin in Example 2 of the present invention;

[0046] Figure 5 This is the thermogravimetric analysis curve of the thermosetting resin in Example 3 of the present invention. DETAILED DESCRIPTION

[0047] The following embodiments are only some embodiments of the present invention, rather than all embodiments. Therefore, the detailed description in the embodiments of the present invention provided below is not intended to limit the scope of the present invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the protection scope of the present invention.

[0048] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments are all conventional methods in the art unless otherwise specified.

[0049] Embodiment 1:

[0050] The thermosetting resin in this embodiment is obtained by the following preparation method:

[0051] 7.8 g of dicyclopentadiene, 0.4 g of ethylidene norbornene, and 10 mg of a catalyst (Grubbs second-generation catalyst, dissolved in a trace amount of dichloromethane) were stirred at 30° C. for 0.16 h to prepare a hard layer prepolymer solution;

[0052] 5.4 g of dicyclopentadiene, 1.9 g of cyclooctene, and 10 mg of catalyst (Grubbs second-generation catalyst, dissolved in a trace amount of dichloromethane) were stirred at 30°C for 0.16 h to prepare a soft layer prepolymer solution;

[0053] Place the PET film on a hot table, heat it to 40°C, and then alternately and repeatedly scrape the soft / hard layer prepolymer solution, with the scraping mass ratio of the soft / hard layer prepolymer solution being 2:3; heat for 0.3h and pre-cure to obtain a low-crosslinking layered material (after pre-curing, the thickness of the single-layer hard layer structure and the single-layer soft layer structure are both 200μm);

[0054] The low cross-linking layered material was heat treated in an oven at 100°C for 3 hours to obtain a thermosetting resin.

[0055] The thermosetting resin prepared in this example was cut into dumbbell-shaped samples (gauge length 50 mm, width 10 mm, thickness 4 mm). The stress-strain curve of the sample was subjected to a tensile test according to the GB / T 2567-2021 resin casting performance test method. Figure 1 The measured tensile strength was 46.5 MPa and the elongation at break was 240%, which proves that the material has excellent mechanical strength. The pictures and scanning electron microscope images of the thermosetting resin samples prepared in this embodiment are shown in Figure 2 and Figure 3 .

[0056] Embodiment 2:

[0057] The thermosetting resin in this embodiment is obtained by the following preparation method:

[0058] 15.6 g of dicyclopentadiene, 0.8 g of ethylidene norbornene, and 20 mg of a catalyst (Grubbs second-generation catalyst, dissolved in a trace amount of dichloromethane) were stirred at 30° C. for 0.16 h to prepare a hard layer prepolymer solution;

[0059] 10.8 g of dicyclopentadiene, 3.8 g of cyclooctene, and 20 mg of catalyst (Grubbs second-generation catalyst, dissolved in a trace amount of dichloromethane) were stirred at 30°C for 0.16 h to prepare a soft layer prepolymer solution;

[0060] The soft / hard layer prepolymer liquid is poured into the mold in sequence, and heated at 40°C for 0.3h for pre-curing to obtain a layered material with a low degree of cross-linking;

[0061] The low cross-linking layered material was heat treated in an oven at 100°C for 3 hours to obtain a thermosetting resin with a thickness of 12 mm.

[0062] The thermosetting resin material prepared in this embodiment was subjected to a ballistic penetration test using a Ruger rifle from a distance of 10 meters. Figure 4As shown, it is proved that the material has excellent impact resistance.

[0063] Embodiment 3:

[0064] The thermosetting resin in this embodiment is obtained by the following preparation method:

[0065] 7.8 g of dicyclopentadiene, 0.4 g of ethylidene norbornene, and 10 mg of a catalyst (Grubbs second-generation catalyst, dissolved in a trace amount of dichloromethane) were stirred at 30° C. for 0.16 h to prepare a hard layer prepolymer solution;

[0066] 5.4 g of dicyclopentadiene, 1.9 g of cyclooctene, and 10 mg of catalyst (Grubbs second-generation catalyst, dissolved in a trace amount of dichloromethane) were stirred at 30°C for 0.16 h to prepare a soft layer prepolymer solution;

[0067] Place the PET film on a hot table, heat it to 40°C, and alternately scrape the soft and hard layer prepolymer liquids, with the scraping mass ratio of the soft / hard layer prepolymer liquids being 2:3; heat for 0.3h and pre-cure to obtain a layered material with a low cross-linking degree;

[0068] The layered material with low cross-linking degree was heat treated in an oven at 100°C for 3 h to further increase the cross-linking density and finally obtain a thermosetting resin.

[0069] The thermosetting resin prepared in this example was subjected to a thermogravimetric test. Figure 5 As shown, the mass loss of the multilayer resin at 400°C is only 3.6%, proving that the material has excellent heat resistance.

[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a thermosetting resin, characterized in that: The following steps are involved: (1) preparing prepolymer solutions of monomer I and monomer II respectively; the monomer I is a mixture of dicyclopentadiene and ethylidene norbornene; the monomer II is a mixture of dicyclopentadiene and cyclooctene; (2) preparing a laminated material formed by pre-curing the pre-polymerized liquid of monomer I and the pre-polymerized liquid of monomer II under heating conditions; (3) Heat-treating the laminated material obtained in step (2) to obtain a thermosetting resin.

2. The preparation method according to claim 1, characterized in that: In step (1), the prepolymer solution of monomer I is obtained by polymerizing monomer I under the action of a catalyst; Preferably, the catalyst is selected from at least one of Grubbs second generation catalyst, Grubbs third generation catalyst, MgBr2 / TiCl4 and KiRuCl3·H2O; Preferably, in the monomer I, the molar ratio of dicyclopentadiene to ethylidene norbornene is 1:0.05-1; Preferably, the mass of the catalyst is 0.1% to 1% of the total mass of the monomer I, more preferably 0.5%.

3. The preparation method according to claim 2, characterized in that: The polymerization reaction temperature is 30 to 50°C; Preferably, the polymerization reaction time is 5 to 10 minutes; Preferably, the polymerization is carried out under stirring.

4. The preparation method according to claim 1, characterized in that: In step (1), the prepolymer solution of monomer II is obtained by polymerizing monomer II under the action of a catalyst; Preferably, the catalyst is selected from at least one of Grubbs second generation catalyst, Grubbs third generation catalyst, MgBr2 / TiCl4 and KiRuCl3·H2O; Preferably, in the monomer II, the molar ratio of dicyclopentadiene to cyclooctene is 1:0.25-1, more preferably 1:0.25-0.8; Preferably, the mass of the catalyst is 0.1% to 1% of the total mass of the monomer II, more preferably 0.5%.

5. The preparation method according to claim 4, characterized in that: The polymerization reaction temperature is 30 to 50°C; Preferably, the polymerization reaction time is 5 to 20 minutes; Preferably, the polymerization is carried out under stirring.

6. The preparation method according to claim 1, characterized in that: In step (2), the heating temperature is 30 to 50° C., and the heating time is 5 to 20 minutes.

7. The preparation method according to claim 1, characterized in that: The preparation process of the laminated material is as follows: ① under heating conditions, the prepolymer liquid of the monomer I and the prepolymer liquid of the monomer II are sequentially coated or alternately coated on the substrate for pre-curing to obtain the laminated material; or, ② the prepolymer liquid of the monomer I and the prepolymer liquid of the monomer II are sequentially injected or alternately injected into a mold, and pre-cured under heating conditions to obtain the laminated material; Preferably, the coating is knife coating.

8. The preparation method according to claim 7, characterized in that: In the sequential coating or sequential alternating coating, the coating mass ratio of the prepolymer solution of monomer I to the prepolymer solution of monomer II is 2-3:3-4; Preferably, in the sequential injection or the sequential and alternating injection, the injection mass ratio of the prepolymer solution of monomer I to the prepolymer solution of monomer II is 2-3:3-4.

9. The preparation method according to claim 1, characterized in that: In step (3), the heat treatment conditions are: temperature 80°C to 120°C, time 1 to 6 hours; Preferably, the heat treatment is heating at 100° C. for 3 hours.

10. Thermosetting resin obtained by the preparation method according to any one of claims 1 to 9.

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