1. A polyimide modifier, characterized by comprising a compound 1 having a structure represented by the structure (1):

wherein R1 is: - (CH)₂)_n1-CH₃Wherein n1 is an integer of 3-18;

r2 is: one of the above structures.

2. The polyimide modifier according to claim 1, further comprising compound 2 having the structure shown in structure (2):

wherein R2 is: one of the structures.

3. The method of preparing the polyimide modifier according to claim 1 or 2, comprising the steps of:

s1, under the protection of inert gas, dispersing the component B in the first raw material in a first organic solvent, adding the first organic solvent into a reaction kettle, dissolving the component A in the first raw material in the first organic solvent, then dropwise adding the first organic solvent into the reaction kettle for reaction, distilling the first organic solvent under reduced pressure, washing the product with water, filtering and drying to obtain a product C; wherein the structural formulas and the reaction formulas of the component A, the component B and the product C are shown as the following formula (I):

wherein R1 is: - (CH)₂)_n1-CH₃Wherein n1 is an integer of 3-18;

s2, sequentially adding the component E in the second raw material, the second organic solvent and the component D in the second raw material into a reaction kettle for reaction, finally adding the product C in the step S1 which is also used as the component of the second raw material, continuing to react for 8-24 hours, pouring the solution into water after the reaction is finished, obtaining a solid, and obtaining the polyimide modifier after washing, extracting and drying; wherein the structural formulas and reaction formulas of the component D, the component E and the obtained polyimide modifier are shown as the following formula (II):

wherein R2 is: one of the structures.

4. The method for preparing the polyimide modifier according to claim 3, wherein in the step S1:

the ratio of the amounts of the substances of the component A to the component B is: (1:0.95) to (1: 1.1);

the first organic solvent comprises one or more of methanol, ethanol, N-butanol, dioxane, tetrahydrofuran, N '-dimethylformamide, N' -dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide;

the mass ratio of the first organic solvent to the first raw material component is as follows: (4:1) to (9: 1);

the reaction conditions were: reacting for 2-24 h at 80-150 ℃, and continuously stirring in the reaction process;

the drying temperature is as follows: 80-120 ℃.

5. The method for preparing the polyimide modifier according to claim 3, wherein in the step S2:

the mass ratio of the products C, the component D and the component E is as follows: c: d: e ═ 2 (1-2): 2: (2-3);

the second organic solvent is one or a combination of more of dichloromethane, trichloromethane, dioxane, tetrahydrofuran, N '-dimethylformamide, N' -dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide;

the mass ratio of the second organic solvent to the second raw material component is as follows: (4:1) to (19: 1);

the reaction conditions after the component E in the second raw material, the second organic solvent and the component D in the second raw material are sequentially added for reaction are as follows: reacting for 8-24 h at 0-30 ℃;

stirring is continued during the reaction of step S2.

6. A resin composition comprising the polyimide modifier according to claim 1 or 2, wherein the resin composition comprises:

100 parts of bismaleimide resin, 4-20 parts of polyimide modifier and 40-80 parts of diallyl phenyl compound.

7. The resin composition of claim 6, wherein the bismaleimide resin comprises:

4,4' -bismaleimide diphenylmethane, 4' -bismaleimide diphenyl ether, N ' - (4, 4' -methylene diphenyl) bismaleimide, N ' - (4-methyl-1, 3-phenylene) bismaleimide, N ' -m-phenylene bismaleimide and 4,4' -bismaleimide diphenyl sulfone.

8. The resin composition of claim 6, wherein the diallylphenyl compound comprises:

one or more of diallyl bisphenol A, diallyl bisphenol A ether and diallyl bisphenol S.

9. A method for preparing the resin composition according to claim 6, comprising the steps of:

mixing the components of the resin composition according to a ratio, stirring and heating to 100-140 ℃, keeping for 0.5-2 h, vacuumizing and defoaming the mixture, and curing to obtain the resin composition, wherein the curing conditions are as follows: heating to 180-250 ℃ and keeping for 2-8 h.

10. The method of preparing a resin composition according to claim 9, wherein the curing conditions are: keeping the temperature of 180-190 ℃ for 0.5-1 h, keeping the temperature of 200-220 ℃ for 1-2 h, and keeping the temperature of 230-250 ℃ for 2-4 h.

Background

Polyimide is a high-molecular material with high heat resistance developed in the 50 th 20 th century, and generally refers to a polymer containing an imide ring in its main chain. Polyimide is a resin which is high temperature resistant, has excellent mechanical, dielectric, mechanical, thermal stability, radiation resistance, chemical corrosion resistance, high resistivity, film forming property and good chemical and dimensional stability, and is widely applied to the fields of aviation, aerospace, nano, liquid crystal, microelectronics, separation membranes, lasers and the like.

Thermosetting polyimide is an important class in polyimide material families, generally is a prepolymer with low relative molecular mass, an imide group and a potential reactive group in a molecular chain, can be polymerized or copolymerized into a three-dimensional space net structure under the initiation of heat and light, selects a proper reactive end group or a proper modifying group, does not emit small molecular volatile matters during curing, and can obtain a matrix resin material which is almost free of air holes and has excellent high-temperature resistance and solvent resistance.

Bismaleimides (BMIs) are maleimide-terminated resins. BMI has the outstanding heat resistance, moisture resistance, radiation resistance, insulation and excellent processability of general thermosetting polyimide, and also has the characteristics of low curing temperature and low curing pressure, and can greatly reduce the processing cost, so that BMI is widely used as a matrix resin of advanced materials and in the electronic industry such as printed circuit boards.

BMI homopolymers are generally brittle, and reactive diluents, chain extenders, comonomers, viscosity modifiers or fillers and the like are generally added to improve the toughness of the cured resin and improve the processability of the resin. However, the heat resistance of the system is usually reduced along with the toughening modification.

Disclosure of Invention

The invention aims to provide a polyimide modifier and a preparation method thereof, wherein the polyimide modifier comprises a compound with a terminal group having straight-chain alkyl and a chain segment having a phenyl ester group, so that the polyimide modifier has excellent processability, and has high temperature resistance and toughening effect after curing.

One aspect of the present invention provides a polyimide modifier, including a compound 1 having a structure represented by the structure (1):

structure (1)

Wherein R1 is: - (CH)₂)_n1-CH₃Wherein n1 is an integer of 3-18;

r2 is: one of the above structures.

Further, the polyimide modifier of the present invention also includes a compound 2 having a structure represented by the structure (2):

structure (2)

Wherein R2 is: one of the structures.

As can be seen from the structure of the compound, the R1 group in the compound of the polyimide modifier is straight-chain alkyl, so that a long-side chain structure is provided for molecules, and the structural compatibility of the molecules is improved.

The invention also provides a preparation method of the polyimide modifier, which comprises the following steps:

s1, under the protection of inert gas, in a reaction kettle with mechanical stirring (the purpose of mechanical stirring is to continuously stir in the reaction process described later), dispersing the component B in the first raw material in a first organic solvent, adding the first organic solvent into the reaction kettle, dissolving the component A in the first raw material in the first organic solvent, then dropwise adding the first organic solvent into the reaction kettle, carrying out reaction, distilling the solvent under reduced pressure, washing the product with water, filtering and drying to obtain a product C; wherein the structural formulas and the reaction formulas of the component A, the component B and the product C are shown as the following formula (I):

formula (I)

Wherein R1 is: - (CH)₂)_n1-CH₃Wherein n1 is an integer of 3-18;

s2, in a dry reaction kettle with mechanical stirring (the purpose of the mechanical stirring is to carry out and keep stirring in the reaction process described later) (namely, the reaction in the step S2 is restarted in a clean and dry reaction kettle, wherein the product C in the step S1 is used as a reactant in the step S2), the component E in the second raw material, the second organic solvent and the component D in the second raw material are sequentially added for reaction, finally, the product C in the step S1 which is also used as the component of the second raw material is added for continuous reaction for 8-24 h, after the reaction is finished, the solution is poured into water to obtain a solid, and the polyimide modifier is obtained after washing, extraction and drying; wherein the structural formulas and reaction formulas of the component D, the component E and the obtained polyimide modifier are shown as the following formula (II):

formula 2

Wherein R2 is: one of the structures.

Further, in step S1, the method includes: the mass ratio of the component A to the component B is as follows: a: b ═ 1:0.95 to 1: 1.1; the first organic solvent is one or a combination of several of methanol, ethanol, N-butanol, dioxane, tetrahydrofuran, N '-dimethylformamide, N' -dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide; the mass ratio of the first organic solvent to the first raw material component is as follows: (4:1) to (9: 1); the reaction conditions were: reacting for 2-24 h at 80-150 ℃; the drying temperature is as follows: and (3) continuously stirring at 80-120 ℃ in the reaction process.

It should be noted that the first raw material in step S1 of the present invention may only contain component a and component B, and no other components, but it is known to those skilled in the art that for organic reactions, it is also common to add some catalysts to promote the reaction in order to increase the reaction speed and speed up the reaction process. Therefore, the mass ratio of the first organic solvent to the first raw material component mentioned above, wherein the first raw material component refers to the components added to the reaction kettle except the first organic solvent in step S1, i.e., when other additives except component a and component B are used in step S1, the mass of the first raw material component is the mass including the added additives. The mass ratio of the first organic solvent to the reactant (including all the materials participating in the reaction) is defined rather than the mass ratio of its dissolved or dispersed components because the first solvent functions as a medium for the condensation reaction, in addition to dissolving the component a and the dispersed component B, to allow the materials participating in the reaction to be sufficiently combined and reacted therein.

Further, in step S2, the method includes: the mass ratio of the products C, the component D and the component E is as follows: c: d: e ═ 2 (1-2): 2: (2-3); the second organic solvent is one or a combination of more of dichloromethane, trichloromethane, dioxane, tetrahydrofuran, N '-dimethylformamide, N' -dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide; the mass ratio of the second organic solvent to the second raw material component is as follows: (4:1) to (19: 1); the reaction conditions after the component E in the second raw material, the second organic solvent and the component D in the second raw material are sequentially added for reaction are as follows: reacting for 8-24 h at 0-30 ℃; stirring was continued throughout the reaction of step S2.

Similarly, step S2 belongs to esterification, it is also common to add auxiliary agents such as catalysts, and the reaction activity of acyl chloride is very high, and it is also allowable to add some components to control the reaction in the later stage of the reaction. Therefore, the mass ratio of the second organic solvent to the second raw material component, wherein the second raw material component also refers to the components added to the reaction kettle in step S2 except the second organic solvent, i.e., when materials except the product C, the component D, and the component E are used in step S2, the mass of the first raw material component includes the mass of the added materials. The mass ratio of the second solvent to the reactants (including all materials participating in the reaction) is also defined because it serves as a medium for the esterification reaction, in addition to dissolving or dispersing the specific components therein, ensuring that the organic reaction is smoothly completed therein.

Compared with other technical approaches which try to improve the toughness of BMI resin by adopting high-performance thermoplastic resin (such as polyether ketone (PEK), polyether ether ketone (PEEK), polyether sulfone (PES), polyether imide (PEI) and the like) through introducing flexible thermoplastic polymer chains, the polyimide modifier with the structure can realize toughening of the bismaleimide resin and ensure the heat resistance of a system.

The present invention also provides a resin composition comprising the above polyimide modifier, the resin composition comprising: 100 parts of bismaleimide resin, 4-20 parts of polyimide modifier and 40-80 parts of diallyl phenyl compound.

Further, the bismaleimide resin includes: 4,4' -bismaleimide diphenylmethane, 4' -bismaleimide diphenyl ether, N ' - (4, 4' -methylene diphenyl) bismaleimide, N ' - (4-methyl-1, 3-phenylene) bismaleimide, N ' -m-phenylene bismaleimide and 4,4' -bismaleimide diphenyl sulfone.

Further, the diallylphenyl compound includes: one or more of diallyl bisphenol A, diallyl bisphenol A ether and diallyl bisphenol S.

The invention also provides a preparation method of the resin composition, which comprises the following steps: mixing the components of the resin composition according to a ratio, stirring and heating to 100-140 ℃, keeping for 0.5-2 h, vacuumizing and defoaming the mixture, and curing to obtain the modified bismaleimide resin, wherein the curing conditions are as follows: heating to 180-250 ℃ and keeping for 2-8 h.

Further, the curing conditions are preferably: keeping the temperature of 180-190 ℃ for 0.5-1 h, keeping the temperature of 200-220 ℃ for 1-2 h, and keeping the temperature of 230-250 ℃ for 2-4 h.

Compared with the prior art, the invention has the advantages that:

1. the polyimide modifier has long side chains, so that molecular chains are not easy to tangle and crystallize, and after the polyimide modifier is blended with bismaleimide resin, a modified blend prepolymer has higher solubility, and the compatibility with other resins is improved.

2. According to the method for blending and modifying the bismaleimide resin by adding the polyimide modifier, the heat resistance of the polyimide resin is maintained, the softening point of the blend prepolymer is reduced, the processing window is widened, the toughness of a resin system is improved, and the method has application value in the fields of high-performance composite materials, high-temperature-resistant adhesives and the like.

3. The invention adopts the blending method for modification, is simple and easy to implement, does not need to increase equipment, has strong implementability and has industrial prospect.

Detailed Description

The present invention will be described in further detail below with reference to specific embodiments in order to make the present invention better understood by those skilled in the art.

Example 1:

under the protection of inert gas nitrogen, 4.28g of 4-hydroxy-1, 8-naphthalic anhydride (0.020mol) is dispersed in 20g of ethanol, 2.53g of n-heptylamine (0.022mol) is dissolved in 7.5g of ethanol and is dripped into the system to react for 24 hours at the temperature of 80 ℃, the solvent is distilled off under reduced pressure, and the product is washed by a large amount of water, filtered and dried at the temperature of 100 ℃ to obtain the product C1 with the yield of 84.1 percent in a reaction kettle with mechanical stirring.

In a drying reaction kettle with mechanical stirring, 3.78g (0.020mol)) of N- (4-hydroxyphenyl) maleimide, 90g N, N '-dimethylacetamide and 5.90g (0.020mol) of 4,4' -diacyl chloride diphenyl ether are sequentially added into the reactants, the mixture is reacted for 8 hours at 20 ℃, 6.23g (0.020mol) of C1 is added, the reaction is continued for 8 hours, the solution is poured into water to obtain a solid, and the solid is washed, extracted and dried to obtain a product F1 with the yield of 71.2%.

Mixing 100 parts of 4,4' -bismaleimide diphenylmethane, 4 parts of F1 and 80 parts of diallyl bisphenol A, heating to 100 ℃, stirring and keeping for 2 hours, vacuumizing and defoaming the mixture, and pouring the mixture into a mold to cure the mixture. The curing conditions were: keeping the temperature at 180 ℃ for 0.5h, keeping the temperature at 200 ℃ for 2h, and keeping the temperature at 230 ℃ for 4 h.

The mixture is introduced into a mold and cured in order to obtain a resin composition of a predetermined shape for subsequent testing and comparative performance analysis. Therefore, in all examples (examples 1 to 5) and comparative examples (comparative examples 1 to 2) of the present invention, the resin compositions before curing were poured into molds of the same shape and size to be cured to obtain test samples of the same size, and then test bars, tests and comparative analyses were prepared under the same conditions as required by the test parameters.

Example 2

Under the protection of inert gas argon, 4.28g (0.020mol) of 4-hydroxy-1, 8-naphthalic anhydride is dispersed in 60g of methanol, 5.66g (0.021mol) of n-octadecylamine is dissolved in 30g of methanol and is dripped into the system to react for 12 hours at the temperature of 100 ℃, the solvent is distilled off under reduced pressure, and the product is washed by a large amount of water, filtered and dried at the temperature of 80 ℃ to obtain the product C2 with the yield of 79.6 percent in a reaction kettle with mechanical stirring.

In a drying reaction kettle with mechanical stirring, reactants of 5.68g (0.030mol) of N- (4-hydroxyphenyl) maleimide, 82g N-methyl pyrrolidone and 10.11g of 2, 2-bis [4- (4-acyl chloride phenoxy) phenyl ] propane are sequentially added, the mixture is reacted for 8 hours at the temperature of 30 ℃, 4.66g (0.010mol) of C2 is added, the reaction is continued for 8 hours, the solution is poured into water to obtain a solid, and a product F2 is obtained after washing, extraction and drying, wherein the yield is 75.7%.

100 parts of 4,4' -bismaleimide diphenyl ether, 20 parts of F2 and 40 parts of diallyl bisphenol A are mixed, heated to 130 ℃, stirred and kept for 1 hour, the mixture is vacuumized and defoamed, and poured into a mold to be solidified. The curing conditions were: keeping the temperature at 180 ℃ for 0.5h, keeping the temperature at 220 ℃ for 1h, and keeping the temperature at 250 ℃ for 2 h.

Example 3

Under the protection of inert gas nitrogen, 4.28g of 4-hydroxy-1, 8-naphthalic anhydride is dispersed in 40g of n-butanol in a reaction kettle with mechanical stirring, 5.12g of n-octadecylamine is dissolved in 13g N-methyl pyrrolidone, the mixture is dripped into the system to react for 8 hours at the temperature of 120 ℃, the solvent is distilled under reduced pressure, the product is washed by a large amount of water, filtered and dried at the temperature of 120 ℃ to obtain the product C3, and the yield is 80.5%.

The method comprises the steps of sequentially adding reactants 4.73g N- (4-hydroxyphenyl) maleimide, 100g N, N '-dimethylformamide and 4.78g of 3,4' -diacyl chloride diphenyl ether into a drying reaction kettle with mechanical stirring, reacting at 0 ℃ for 24 hours, adding 6.99g C3, continuing to react for 8 hours, pouring the solution into water after the reaction is finished to obtain a solid, and washing, extracting and drying to obtain a product F3 with the yield of 69.8%.

100 parts of N, N '- (4, 4' -methylenediphenyl) bismaleimide, 16 parts of F3 and 50 parts of diallyl bisphenol A ether are mixed, heated to 130 ℃, stirred and kept for 1 hour, the mixture is vacuumized and defoamed, and poured into a mold to be solidified. The curing conditions were: keeping the temperature at 180 ℃ for 0.5h, keeping the temperature at 200 ℃ for 2h, and keeping the temperature at 240 ℃ for 3 h.

Example 4

Under the protection of inert gas argon, 4.28g of 4-hydroxy-1, 8-naphthalic anhydride is dispersed in 26g of dioxane in a reaction kettle with mechanical stirring, 3.99g of tridecylamine is dissolved in 8g of dioxane and is added into the system dropwise, the reaction is carried out for 6 hours at the temperature of 130 ℃, the solvent is distilled under reduced pressure, the product is washed by a large amount of water, filtered and dried at the temperature of 120 ℃, and the product C4 is obtained, wherein the yield is 80.9%.

The method comprises the steps of sequentially adding reactants 4.73g N- (4-hydroxyphenyl) maleimide, 279g of chloroform/dimethyl sulfoxide and 4.06g of terephthaloyl chloride into a drying reaction kettle with mechanical stirring, reacting at 10 ℃ for 12 hours, adding 5.93g C4, continuing to react for 8 hours, pouring the solution into water after the reaction is finished to obtain a solid, and washing, extracting and drying to obtain a product F4 with the yield of 74.1%.

100 parts of N, N' -m-phenylene bismaleimide, 12 parts of F4 and 60 parts of diallyl bisphenol A ether are mixed, heated to 130 ℃, stirred and kept for 1 hour, the mixture is vacuumized and defoamed, and poured into a mold to be solidified. The curing conditions were: keeping the temperature at 180 ℃ for 0.5h, keeping the temperature at 200 ℃ for 2h, and keeping the temperature at 240 ℃ for 3 h.

Example 5

Under the protection of inert gas nitrogen, 4.28g of 4-hydroxy-1, 8-naphthalic anhydride is dispersed in 20g of tetrahydrofuran in a reaction kettle with mechanical stirring, 1.54g of n-butylamine is dissolved in 8g of tetrahydrofuran, the mixture is dripped into the system, the reaction is carried out for 2 hours at the temperature of 150 ℃, the solvent is distilled under reduced pressure, the product is washed by a large amount of water, filtered and dried at the temperature of 110 ℃ to obtain the product C5, and the yield is 77.3%.

The method comprises the steps of sequentially adding reactants 5.68g N- (4-hydroxyphenyl) maleimide, 90g dioxane and 5.58g 4,4' -biphenyl diformyl chloride into a drying reaction kettle with mechanical stirring, reacting at 5 ℃ for 18h, adding 2.69g C5, continuing to react for 8h, pouring the solution into water after the reaction is finished, obtaining a solid, washing with water, extracting and drying to obtain a product F5, wherein the yield is 70.2%.

100 parts of 4,4' -bismaleimide diphenyl sulfone, 8 parts of F5 and 60 parts of diallyl bisphenol S are mixed, heated to 140 ℃, stirred and kept for 0.5h, the mixture is vacuumized and defoamed, and poured into a mold to be solidified. The curing conditions were: keeping the temperature at 180 ℃ for 0.5h, keeping the temperature at 200 ℃ for 2h, and keeping the temperature at 240 ℃ for 3 h.

Comparative example 1

Mixing 100 parts of 4,4' -bismaleimide diphenylmethane and 80 parts of diallyl bisphenol A, heating to 130 ℃, stirring and keeping for 1h, vacuumizing and defoaming the mixture, and pouring into a mold to cure the mixture. The curing conditions were: keeping the temperature at 180 ℃ for 0.5h, keeping the temperature at 200 ℃ for 2h, and keeping the temperature at 230 ℃ for 4 h.

Comparative example 2

100 parts of N, N' -m-phenylene bismaleimide and 80 parts of diallyl bisphenol A are mixed, heated to 130 ℃, stirred and kept for 1 hour, the mixture is vacuumized and defoamed, and poured into a mold to be solidified. The curing conditions were: keeping the temperature at 180 ℃ for 0.5h, keeping the temperature at 220 ℃ for 1h, and keeping the temperature at 250 ℃ for 2 h.

Comparative example 3

The reaction product 7.57g N- (4-hydroxyphenyl) maleimide, 30.68g dioxane and 5.58g 4,4' -biphenyl diformyl chloride are sequentially added into a drying reaction kettle with mechanical stirring, the reaction lasts for 18h at 5 ℃, after the reaction is finished, the solution is poured into water to obtain a solid, and the solid is washed, extracted and dried to obtain the product D3 with the yield of 83.2%.

The product D3 was used as the final product and was subjected to test analysis together with the final products of the other examples or comparative examples.

And (3) performance testing:

(1) preparation of test specimens reference is made to: compression molding of GB/T5471-;

(2) impact performance test reference: measuring the impact strength of the GB/T1843-2008 plastic cantilever;

(3) heat resistance test reference: GB/T22567-.

The test data of the final product obtained in each example are shown in table 1 below.

TABLE 1 data of the performance tests on the final products obtained in the examples of the invention

Performance index	Impact Strength (kJ/m)2)	Glass transition temperature (. degree. C.)
			Example 1	16.3	271
Example 2	19.5	289
			Example 3	18.2	284
Example 4	17.9	285
			Example 5	17.5	283
Comparative example 1	14.3	248
			Comparative example 2	13.2	264
Comparative example 3	7.3	261

From the above performance test results, it can be seen that the impact strength and glass transition temperature of the resin composition obtained by the present invention, which is obtained by introducing a polyimide having a predetermined group (i.e., the present invention includes a polyimide modifier having a compound of a specified structure) into a bismaleimide resin system and performing a modification treatment, are significantly improved as compared to those of the bismaleimide resin or the polyimide modifier itself.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.