A hyperbranched polyimide-based flow modifier, its preparation method and application

Abstract

The present invention discloses a hyperbranched polyimide-based flow modifier and its preparation method and application: In this preparation method, 4,4'-diaminodiphenyl ether is dissolved in a first solvent, and a dianhydride monomer is added, followed by stirring and reacting to obtain a polyamic acid solution with acid anhydride end groups; the obtained solution is mixed with melamine and reacted at 200 °C. After cooling, it is poured into an excessive amount of a second solvent, and precipitation occurs. After filtration and drying, a hyperbranched polyimide-based flow modifier is obtained. When this flow modifier is used for PEEK materials, compared with existing additives, the thermal weight loss temperature of this flow modifier is > 360 °C, and the flow performance of PEEK is improved by 24% after addition and use.

Description

Technical Field

[0001] The present invention relates to the technical field of resin materials, and particularly to a hyperbranched polyimide-based flow modifier, its preparation method and application, and this flow modifier is used to improve the melt processing performance of PEEK. Background Art

[0002] PEEK (polyetheretherketone) is an aromatic crystalline thermoplastic polymer material, which has advantages such as high mechanical strength, high temperature resistance, impact resistance, flame retardancy, acid and alkali resistance, hydrolysis resistance, wear resistance, fatigue resistance, and radiation resistance. PEEK can replace traditional materials such as metals and ceramics in many special fields, and it is one of the most popular high-performance engineering plastics today, and is mainly applied to fields such as aerospace, automotive industry, electronic and electrical, and medical devices. However, PEEK has a high melting point and a large melt viscosity, and it is difficult to form and process, especially it is particularly difficult to prepare fiber-reinforced PEEK composites with low porosity.

[0003] Flow modifiers can partially disentangle the molecular chains of polymer materials, reduce the intermolecular force, thereby reducing the melt viscosity and improving the processing performance. However, traditional flow modifiers are difficult to stably exist at the melting temperature of PEEK, and premature decomposition not only fails to improve the processing performance of PEEK, but the residual decomposition products will also affect the performance of the PEEK material itself. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. For this reason, the present invention provides a hyperbranched polyimide-based flow modifier, its preparation method and application, which are used to improve the melt processing performance of PEEK.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] A hyperbranched polyimide-based flow modifier, comprising a structural unit shown in formula (i) and a structural unit shown in formula (ii):

[0007]

[0008] Wherein, X is

[0009] As a preferred technical solution of the present invention: the molar ratio of the triazine ring structure in formula (i) to the phenyl ether structure in formula (ii) is 1:(2 - 6).

[0010] Preferably, the number average molecular weight of the flow modifier is 5×10 3 -3×10 4 g / mol.

[0011] Through research, it is found that: if the proportion of the triazine ring is too high, it will lead to too low decomposition temperature of the flow modifier, which will not only reduce the effect of the flow modifier, but also decompose to produce small molecules that affect the crystallization behavior of PEEK. If the proportion of the triazine ring is too low, the flow modification effect is weak, and more flow modifiers need to be added, which is not conducive to the performance of the CF / PEEK composite material.

[0012] The present invention provides a method for preparing the hyperbranched polyimide-based flow modifier for PEEK as described above, comprising the following steps:

[0013] (1) Dissolve 4,4'-diaminodiphenyl ether in a first solvent, and add a dianhydride monomer. Control the molar ratio of 4,4'-diaminodiphenyl ether to the dianhydride monomer to be 1:1 - 2, and stir and react for 12 - 36 hours to obtain a polyamic acid solution with acid anhydride end groups;

[0014] (2) Mix the solution obtained in step (1) with melamine. Control the molar ratio of polyamic acid to melamine in the solution to be 3 - 12:1, react at 200 °C for 6 - 12 hours, cool and pour it into an excessive second solvent. Precipitates will form. After filtration and drying, a hyperbranched polyimide-based flow modifier is obtained.

[0015] To further achieve the object of the present invention, preferably, the dianhydride monomer is one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenylether tetracarboxylic dianhydride.

[0016] Preferably, the molar ratio of the triazine ring structure in formula (i) to the phenyl ether structure in formula (ii) is 1:(2 - 6)

[0017] Preferably, in step (1), the dosage of the first solvent is 8 - 12 times the total amount of 4,4'-diaminodiphenyl ether and the dianhydride monomer; the first solvent is one or a mixture of acetone, dimethyl sulfoxide, N,N-dimethylformamide, and dimethylacetamide.

[0018] Preferably, in step (2), the dosage of the second solvent is 1 - 5 times that of the first solvent; the second solvent is one or a mixture of deionized water, methanol, ethanol, propanol, and isopropanol.

[0019] The present invention further provides the application of the hyperbranched polyimide-based flow modifier in the preparation of thermoplastic resins, for preparing PEEK materials.

[0020] According to the above application, preferably, the mass ratio of the flow modifier to the PEEK resin is 1:(5 - 100).

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) There is a phenyl ether bond in 4,4'-diaminodiphenyl ether, which has a certain similarity with the molecular structure of PEEK, and can improve the compatibility of the flow modifier in the PEEK material;

[0023] (1) By controlling the reaction ratio of melamine to 4,4'-diaminodiphenyl ether, the thermal stability of the flow modifier can be improved, and it can remain stable during the melt processing of PEEK;

[0024] (3) The reaction monomers 4,4'-diaminodiphenyl ether, melamine, and dianhydride monomer are all relatively common chemical raw materials, and the whole reaction has industrial benefits and industrialization value. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the infrared spectrum diagram of the hyperbranched polyimide-based flow modifier obtained in Example 1.

[0026] Figure 2 It is the thermogravimetric curve of the hyperbranched polyimide-based flow modifier obtained in Example 1.

[0027] Figure 3 It is the thin layer chromatography analysis spectrum diagram of the reactants and reaction products in Example 1.

[0028] Figure 4 It is the infiltration picture of PEEK added with the hyperbranched polyimide-based flow modifier obtained in Example 1 to carbon fiber.

[0029] Figure 5 It is the infiltration picture of PEEK without adding any flow modifier to carbon fiber. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] To better support the present invention, the following examples and drawings are used to further illustrate the present invention, but the implementation manners of the present invention are not limited thereto.

[0031] Example 1

[0032] (1) Dissolve 4,4'-diaminodiphenyl ether in N,N-dimethylformamide, and add biphenyltetracarboxylic dianhydride. Control the molar ratio of 4,4'-diaminodiphenyl ether to biphenyltetracarboxylic dianhydride to be 1:1.5, and stir and react for 24 hours to obtain a polyamic acid solution with acid anhydride end groups;

[0033] (2) Mix the solution obtained in step (1) with melamine, control the molar ratio of polyamic acid to melamine in the solution to be 10:1, react at 200 °C for 8 hours, pour it into excessive deionized water after cooling, precipitate will form, filter by suction and dry to obtain HBPI-1, and the yield is 71%.

[0034] The infrared characterization of HBPI-1 is shown in Figure 1 , and the decomposition temperature characterization is shown in Figure 2 .

[0035] The reaction process was observed by thin-layer chromatography analysis. The left spot is 4,4'-diaminodiphenyl ether, the middle spot is biphenyltetracarboxylic dianhydride, and the right spot is the reaction product. Among them, there is no benzene ring in the molecular structure of melamine, so it cannot be analyzed by thin-layer chromatography; methanol and dichloromethane are used to dissolve biphenyltetracarboxylic dianhydride, and a small amount of water in the solvent and silica gel plate may cause the decomposition of the acid anhydride, resulting in tailing during the plate climbing process; the product is a polymer and is a stationary point. It can be concluded from Figure 3 that there is no 4,4'-diaminodiphenyl ether and biphenyltetracarboxylic dianhydride in the product, and both have reacted completely.

[0036] Example 2

[0037] (1) Dissolve 4,4'-diaminodiphenyl ether in N,N-dimethylformamide, add biphenyltetracarboxylic dianhydride, control the molar ratio of 4,4'-diaminodiphenyl ether to biphenyltetracarboxylic dianhydride to be 1:1.5, stir and react for 24 hours to obtain a polyamic acid solution with acid anhydride end groups;

[0038] (2) Mix the solution obtained in step (1) with melamine, control the molar ratio of polyamic acid to melamine in the solution to be 6:1, react at 200 °C for 8 hours, pour it into excessive deionized water after cooling, precipitate will form, filter by suction and dry to obtain HBPI-2, and the yield is 74%.

[0039] Comparative Example 1

[0040] Dissolve melamine in N,N-dimethylformamide, add biphenyltetracarboxylic dianhydride, control the molar ratio of melamine to biphenyltetracarboxylic dianhydride in the solution to be 1:1.5, react at 200 °C for 8 hours, pour it into excessive deionized water after cooling, precipitate will form, filter by suction and dry to obtain HBPI-3, and the yield is 86%.

[0041] The flow modifiers obtained by the above embodiments were respectively mixed with PEEK powder at a mass ratio of 1:20, pressed at 360 °C and 5 MPa for 10 minutes to form wafers with a diameter of 40 mm and a thickness of 0.1 mm, and then placed on carbon fiber cloth respectively, and pressed at 360 °C and 5 MPa for 30 minutes to form. The wetting area of PEEK on the carbon fiber cloth was measured, and the wetting area of PEEK on the carbon fiber cloth without adding any flow modifier was compared to characterize the flow performance of PEEK.

[0042] Table 1 Decomposition temperature and percentage increase in wetting area of examples and comparative examples

[0043] <![CDATA[Thermogravimetric temperature T d5％ / ℃]]> Percentage increase in infiltration area HBPI-1 392 24％ HBPI-2 388 22％ HBPI-3 335 8％

[0044] As can be seen from Table 1, due to the different proportions of triazine rings in their respective molecular structures (the theoretical molar ratios of the triazine ring structure of formula i to the phenyl ether structure of formula ii in the molecular structures of HBPI-1 and HBPI-2 are 1:4 and 1:2.4 respectively, and HBPI-3 has no phenyl ether structure unit), the thermal weight loss temperatures of HBPI-1 and HBPI-2 are significantly higher than that of HBPI-3 in the comparative example, and are both higher than the molding temperature of PEEK, meeting the molding requirements of PEEK. After being mixed with PEEK, the wetting area of PEEK on the carbon fiber cloth is significantly increased, indicating that the fluidity of PEEK is improved.

[0045] Among them, Figure 4 is a picture of the wetting of carbon fiber by PEEK added with the hyperbranched polyimide-based flow modifier obtained in Example 1. Figure 5 is a picture of the wetting of carbon fiber by PEEK without adding any flow modifier.

[0046] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A preparation method of a hyperbranched polyimide-based flow modifier, characterized in that: The flow modifier includes a structural unit represented by formula (i) and a structural unit represented by formula (ii): wherein, X is The molar ratio of the triazine ring structure in formula (i) to the phenyl ether structure in formula (ii) is 1:(2 - 6); The number-average molecular weight of the flow modifier is 5×10 3 -3×10 4 g / mol; The preparation method of the hyperbranched polyimide-based flow modifier includes the following steps: (1) Dissolve 4,4'-diaminodiphenyl ether in a first solvent, add a dianhydride monomer, control the molar ratio of 4,4'-diaminodiphenyl ether to the dianhydride monomer to be 1:1 - 2, and stir and react for 12 - 36 hours to obtain a polyamic acid solution with acid anhydride end groups; (2) Mix the solution obtained in step (1) with melamine, control the molar ratio of polyamic acid to melamine in the solution to be 3 - 12:1, react at 200 °C for 6 - 12 hours, cool and pour it into an excessive second solvent, precipitate will form, filter by suction and dry to obtain the hyperbranched polyimide-based flow modifier.

2. The preparation method of the hyperbranched polyimide-based flow modifier according to claim 1, characterized in that The dianhydride monomer is one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenylether tetracarboxylic dianhydride.

3. The preparation method of the hyperbranched polyimide-based flow modifier according to claim 1, characterized in that In step (1), the dosage of the first solvent is 8 - 12 times the total amount of 4,4'-diaminodiphenyl ether and the dianhydride monomer; the first solvent is one or a mixture of acetone, dimethyl sulfoxide, N,N-dimethylformamide, and dimethylacetamide.

4. The preparation method of the hyperbranched polyimide-based flow modifier according to claim 1, characterized in that, In step (2), the dosage of the second solvent is 1 - 5 times that of the first solvent; the second solvent is one or a mixture of deionized water, methanol, ethanol, propanol, and isopropanol.

5. Application of a hyperbranched polyimide-based flow modifier in the preparation of a thermoplastic resin composite material, the hyperbranched polyimide-based flow modifier is prepared by the method according to any one of claims 1 - 4, and the thermoplastic resin is a PEEK resin.

6. The application according to claim 5, wherein, The mass ratio of the flow modifier to the PEEK resin is 1:(5 - 1900).

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