Epoxy resin composite material for aviation stretch-forming die and preparation method

Abstract

The invention discloses a preparation method of an epoxy resin composite material for an aviation stretch-forming die. The preparation method comprises the following steps: 1, adding a main material epoxy resin into a vacuum stirrer for stirring and defoaming; step 2, adding filler aluminum hydroxide powder into the vacuum stirrer for stirring and defoaming; step 3, adding a flexibilizer and a diluent into the vacuum stirrer, and continuously stirring and defoaming; 4, finally, a curing agent is added into the vacuum stirring machine to be fully defoamed and stirred; and 5, adding the uniformly stirred mixture in the step 4 into a forming mold, and carrying out curing forming to finally obtain the epoxy resin composite material for the aviation stretch-forming mold. The aluminum hydroxide and epoxy resin mixed material is adopted, and the defects that a traditional epoxy resin stretch-forming die material is poor in heat resistance, prone to aging, low in hardness and the like are overcome. In addition, by adding the curing agent, the flexibilizer and the diluent, the material for the stretch-forming die is cured at normal temperature, so that the production cost is reduced, and the mechanical property is improved.

Description

Technical Field

[0001] The invention relates to the technical field of mold materials, and in particular provides an epoxy resin composite material for an aviation drawing mold and a preparation method thereof. Background Art

[0002] The design and manufacture of skin pulling dies is one of the key technologies in aviation process equipment. The use of advanced design and manufacturing technology to fully guarantee the forming accuracy and reliability of skin pulling dies in terms of materials and structure is a bottleneck problem that needs to be solved urgently in the current aviation manufacturing industry. Traditional pulling dies are mostly made of steel and aluminum. Due to their high density and rigidity, they increase costs and are difficult to transport and install. Epoxy resin has excellent mechanical properties and can be processed by various mechanical cutting processes; the product has good dimensional stability, is not easy to crack, and can be cured at room temperature. Epoxy resin has a small molecular weight and good fluidity at room temperature. It reacts with various curing agents and various fillers.

[0003] Aluminum hydroxide powder is a common filler. It is often added to composite materials as a filler because of its certain mechanical properties, non-toxic and harmless environmental properties, and price advantage of reducing costs. And with the increase in the amount of aluminum hydroxide, the thermal stability of the product gradually improves, showing excellent flame retardant effect. In addition, the addition of aluminum hydroxide also improves other properties of the material. When the aluminum hydroxide content reaches a certain value, it can reach the best ratio with other components, and the product can have good physical properties, thereby improving the mechanical properties of the material.

[0004] In the production of aircraft skin parts, drawing dies are mainly used to produce double-curvature parts with large surface area, thin thickness and high surface quality requirements. Parts suitable for drawing generally have the following characteristics: high surface quality requirements, high shape accuracy, complex shape and large size. With the development demand for large-scale aircraft models, traditional molds may weigh several tons, with high manufacturing costs and long production cycles, so the structural form and mold performance of drawing dies are also constantly innovating.

[0005] In summary, it is very meaningful to provide a new type of material for aviation drawing dies. Summary of the invention

[0006] In view of the problems in the prior art regarding materials for aviation drawing dies, the present invention provides an epoxy resin composite material for aviation drawing dies and a preparation method thereof.

[0007] The present invention firstly proposes an epoxy resin composite material for an aviation drawing die, which comprises, by weight:

[0008] Main ingredient: epoxy resin 1-1.2 parts;

[0009] Filler aluminum hydroxide powder 3.5-4.5 parts;

[0010] Toughener 0.2-0.5 parts;

[0011] Diluent 0.4-0.6 parts.

[0012] The present invention also provides a method for preparing the epoxy resin composite material for aviation drawing mold, comprising the following steps:

[0013] Step 1: Add the main material epoxy resin into a vacuum mixer for stirring and degassing;

[0014] Step 2: Add filler aluminum hydroxide powder into the vacuum mixer for stirring and degassing; the added mass of aluminum hydroxide is in multiple relationship with the mass of epoxy resin;

[0015] Step 3: After the epoxy resin and aluminum hydroxide powder are evenly mixed, add toughening agent and diluent into the vacuum mixer and continue to stir and degas;

[0016] Step 4: Finally, add the curing agent into the vacuum mixer for sufficient degassing and stirring;

[0017] Step 5: Add the mixture stirred evenly in step 4 into a molding mold for curing and molding, and finally obtain an epoxy resin composite material for aviation drawing molds.

[0018] Preferably, the stirring time of step 1 is 10 min, and the stirring power is 2000-2200 W.

[0019] Preferably, the stirring time of step 2 is 20 min, and the stirring power is 2000-2300 W.

[0020] Preferably, the diluent in step 3 is of glycidyl ether type.

[0021] Preferably, the toughening agent in step 3 is one of dibutyl phthalate, BI7774, and WD-401.

[0022] Preferably, the curing agent in step 4 is m-xylylenediamine; the stirring and degassing time is 30 minutes; and the stirring power is 2000-2300W.

[0023] Preferably, before the molding mold described in step 5 is used, the pretreatment method includes: cleaning the molding mold; and evenly applying silicone grease release agent on the cleaned mold surface; wherein the cleaning method is: using anhydrous ethanol as a cleaning solvent to clean the mold, and after cleaning, placing the mold in an oven for heating, and the heating temperature is 60 to 70°C.

[0024] Preferably, the curing condition in step 5 is room temperature curing for 6-7 hours.

[0025] The epoxy resin composite material for aviation drawing molds and the preparation method provided by the present invention adopt aluminum hydroxide and epoxy resin mixed materials to improve the shortcomings of traditional epoxy resin drawing mold materials such as poor heat resistance, easy aging, low hardness, etc. In addition, by adding a curing agent, a toughening agent and a diluent, the drawing mold material can be cured at room temperature, thereby reducing production costs and improving mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0027] Figure 1 The present invention is a schematic diagram of the reaction mechanism of the method for preparing the epoxy resin composite material for aviation drawing molds provided by the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further explained below in conjunction with specific implementation schemes, but the present invention is not limited thereto.

[0029] In order to solve the technical problems of the existing drawing die materials for aviation molds. The present invention adopts the method of mixing aluminum hydroxide and epoxy resin to improve the shortcomings of traditional epoxy resin drawing die materials such as poor heat resistance, easy aging, and low hardness. In addition, by adding a curing agent, a toughening agent, and a diluent, the drawing die material can be cured at room temperature, thereby reducing production costs and improving mechanical properties.

[0030] The preparation method of the epoxy resin composite material for aviation drawing mold comprises the following steps:

[0031] Step 1: Add 1-1.2 parts of epoxy resin into a vacuum mixer and stir and degas;

[0032] Step 2: Add 3.5-4.5 parts of aluminum hydroxide powder into the vacuum mixer for stirring and degassing;

[0033] Step 3: After the epoxy resin and aluminum hydroxide powder are evenly mixed, 0.2-0.5 parts of toughening agent and 0.4-0.6 parts of diluent are added to the vacuum mixer, and the stirring and degassing are continued;

[0034] Step 4: Finally, add the curing agent into the vacuum mixer for sufficient degassing and stirring;

[0035] Step 5: Add the mixture stirred evenly in step 4 into a molding mold for curing and molding, and finally obtain an epoxy resin composite material for aviation drawing molds.

[0036] Since the proportion of aluminum hydroxide is too high, the mixture of epoxy resin and aluminum hydroxide is difficult to stir. Adding a diluent can reduce the viscosity of the material, make the aluminum hydroxide dispersed more evenly, and mix aluminum hydroxide and epoxy resin more fully. The addition of a toughening agent improves the mechanical properties of the composite material.

[0037] The stirring time of step 1 is 10 min, the stirring power is 2000-2200 W, and the stirring time of step 2 is 20 min;

[0038] In step 2, the stirring power is 2000-2200W;

[0039] The diluent in step 3 is of glycidyl ether type; the toughening agent is one of dibutyl phthalate, BI7774, and WD-401.

[0040] The curing agent in step 4 is m-xylylenediamine; the stirring and degassing time is 30 minutes; the stirring power is 2000-2200W;

[0041] Step 5: Treat the mold required for composite material molding and keep it clean. Apply silicone grease release agent evenly on the cleaned mold surface to facilitate demolding after the mold is cured.

[0042] The above-mentioned treatment method includes: cleaning the molding mold; and evenly applying silicone grease release agent on the cleaned mold surface; wherein the cleaning method is: using anhydrous ethanol as a cleaning solvent to clean the mold, and after cleaning, placing the mold in an oven for heating, and the heating temperature is 60 to 70°C.

[0043] The mechanical properties of the material obtained by the present invention are measured by three-point bending test, tensile property test and compression property test, and the national standards based on them are GB / T 9341-2008, GB / T1040.2-2006 and GB\T 1041-2008 respectively.

[0044] Epoxy resin-based composite materials have large cohesion and a dense molecular structure, so they have good mechanical properties and can be processed by various mechanical cutting processes; the curing shrinkage is small, which can ensure the stability of product size, not easy to crack, and is conducive to demolding. The curing temperature can vary in the range of 0 to 180 ° C, and the process performance is good. The production process is environmentally friendly and meets high occupational hygiene conditions, which can greatly reduce the manufacturing cost of aircraft skins. In addition, the benzene ring structure and high cross-linking density three-dimensional network structure in epoxy resin make epoxy resin have high strength while showing the characteristics of high fracture brittleness and poor toughness. The added toughening agent effectively improves the bending resistance, fatigue resistance and cold and hot shock resistance of the mold; the overall viscosity of the mixture is large, which is not conducive to the mixing of the components. The added active diluent can reduce the viscosity of the mixed system, increase the fluidity of the material, and extend the service life. While improving the mixing operability, it can also improve the overall mechanical properties of the drawing die. In addition, the active diluent used not only dilutes the epoxy resin, but also participates in the curing reaction to undergo chemical changes.

[0045] The synthesis process of the composite material of the present invention successively undergoes two steps of ring-opening etherification and epoxidation. The glycidyl ether type diluent selected in the present invention not only has low viscosity, but also has good compatibility with epoxy resin. The presence of ether bonds and epoxy groups makes its dilution effect better, because it can participate in a partial curing reaction, so the dilution effect is better than other active diluents.

[0046] Example 1

[0047] An epoxy resin composite material for an aviation drawing die and a preparation method thereof, which specifically comprises the following steps in parts by weight:

[0048] (1) The mold into which the mixture is to be injected is cleaned with anhydrous ethanol, and the cleaned mold is placed in an oven and heated to evaporate the ethanol.

[0049] (2) Weigh 1 part of epoxy resin and add it into a vacuum degassing barrel for stirring and degassing. The stirring time is 10 minutes, the stirring power is 2000 W, and the stirring time is 10 minutes.

[0050] (3) Add 4 parts of aluminum hydroxide powder to 1 part of epoxy resin after stirring and degassing, and continue to degas and stir.

[0051] (4) After stirring and degassing for 20 minutes, add 0.3 parts of toughening agent and 0.4 parts of diluent into the stirring barrel, and continue to stir and degas. After adding the toughening agent and diluent, continue to degas and stir for 20 minutes; the diluent is benzyl glycidyl ether; the toughening agent is a type of dibutyl phthalate.

[0052] (5) Finally, add the curing agent m-xylylenediamine to the prepolymer: add 0.25 parts of the curing agent, and continue to stir and degas after adding the curing agent. The degassing time is 30 minutes.

[0053] (6) Add the evenly stirred mixture into a pre-prepared molding mold for solidification and molding. Test its various mechanical properties according to national standards.

[0054] Example 2

[0055] An epoxy resin composite material for an aviation drawing die and a preparation method thereof, specifically comprising the following steps:

[0056] (1) The mold into which the mixture is to be injected is cleaned with anhydrous ethanol, and the cleaned mold is placed in an oven and heated to evaporate the ethanol.

[0057] (2) Weigh 1 part of epoxy resin and add it into a vacuum degassing barrel for stirring and degassing. The stirring time is 10 minutes, the stirring power is 2000 W, and the stirring time is 10 minutes.

[0058] (3) Add 3.5 parts of aluminum hydroxide to the epoxy resin after stirring and degassing, and continue to stir and degas.

[0059] (4) After degassing and stirring for 20 minutes, add 0.5 parts of toughening agent and 0.5 parts of diluent into the stirring barrel, and continue to stir and degas. After adding the toughening agent and diluent, continue to degas and stir for 20 minutes. The diluent is benzyl glycidyl ether; the toughening agent is BI7774;

[0060] (5) Finally, add the curing agent to the prepolymer. Add 0.2 parts of curing agent m-xylylenediamine. Continue to stir and degas after adding the curing agent. The degassing time is 30 minutes.

[0061] (6) Add the evenly stirred mixture into a pre-prepared molding mold for solidification and molding. Test its various mechanical properties according to national standards.

[0062] The diluent is of glycidyl ether type; the toughening agent is one of dibutyl phthalate, BI7774 and WD-401.

[0063] Example 3

[0064] A method for preparing an epoxy resin composite material for an aviation drawing die comprises the following steps:

[0065] (1) The mold into which the mixture is to be injected is cleaned with anhydrous ethanol, and the cleaned mold is placed in an oven and heated to evaporate the ethanol.

[0066] (2) Weigh 1 part of epoxy resin and add it into a vacuum degassing barrel for stirring and degassing. The stirring time is 10 minutes, the stirring power is 2000 W, and the stirring time is 10 minutes.

[0067] (3) Add 4.5 parts of aluminum hydroxide to the epoxy resin after stirring and degassing, and continue to stir and degas.

[0068] (4) After degassing and stirring for 20 minutes, add 0.2 parts of toughening agent and 0.5 parts of diluent into the stirring barrel, and continue to stir and degas. After adding the toughening agent and diluent, continue to degas and stir for 20 minutes. The diluent is benzyl glycidyl ether; the toughening agent is WD-401.

[0069] (5) Finally, add the curing agent to the prepolymer. Add 0.3 parts of curing agent m-xylylenediamine. Continue to stir and degas after adding the curing agent. The degassing time is 30 minutes.

[0070] (6) Add the evenly stirred mixture into a previously prepared molding mold for solidification and molding.

[0071] And its various mechanical properties are tested according to national standards.

[0072] Example 4

[0073] A method for preparing an epoxy resin composite material for an aviation drawing die comprises the following steps:

[0074] (1) The mold into which the mixture is to be injected is cleaned with anhydrous ethanol, and the cleaned mold is placed in an oven and heated to evaporate the ethanol.

[0075] (2) Weigh 1.2 parts of epoxy resin and add it into a vacuum degassing barrel for stirring and degassing. The stirring time is 10 minutes, the stirring power is 2000 W, and the stirring time is 10 minutes.

[0076] (3) Add 4 parts of aluminum hydroxide to the epoxy resin after stirring and degassing, and continue to stir and degas.

[0077] (4) After degassing and stirring for 20 minutes, add 0.3 parts of toughening agent and 0.4 parts of diluent into the stirring bucket and continue to stir and degas. After adding toughening agent dibutyl phthalate and diluent benzyl glycidyl ether, continue to degas and stir for 20 minutes.

[0078] (5) Finally, add the curing agent m-xylylenediamine to the prepolymer. Add 0.3 parts of the curing agent. Continue to stir and degas after adding the curing agent. The degassing time is 30 minutes.

[0079] (6) Add the evenly stirred mixture into a previously prepared molding mold for solidification and molding.

[0080] And its various mechanical properties are tested according to national standards.

[0081] Comparative Example 1

[0082] An epoxy resin composite material for aviation drawing molds and a preparation method thereof are the same as those of Example 1, except that there is no step (4), and only aluminum hydroxide and epoxy resin are mixed, which is difficult to stir and cannot be mixed evenly.

[0083] The test results of the embodiment materials are shown in the following table:

[0084] Test items Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Bending strength(MPa) 65.4 35.4 50.4 70.4 19.4 Tensile strength(MPa) 19.6 12.8 17.9 19.2 6.2 Compression strength(MPa) 25.6 13.7 23.7 37.3 12.3

[0085] The detailed description of the present invention is written in a progressive manner, emphasizing the differences between the various implementations, and similar parts thereof can be referred to each other.

[0086] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. An epoxy resin composite material for an aviation drawing die, characterized in that: In parts by weight, it includes: Main ingredient: epoxy resin 1-1.2 parts; Filler aluminum hydroxide powder 3.5-4.5 parts; Toughener 0.2-0.5 parts; Diluent 0.4-0.6 parts.

2. The method for preparing the epoxy resin composite material for aviation drawing mold according to claim 1, characterized in that: The steps include: Step 1: Add the main material epoxy resin into a vacuum mixer for stirring and degassing; Step 2: Add filler aluminum hydroxide powder into the vacuum mixer for stirring and degassing; the added mass of aluminum hydroxide is in multiple relationship with the mass of epoxy resin; Step 3: After the epoxy resin and aluminum hydroxide powder are evenly mixed, a toughening agent and a diluent are added to the vacuum mixer, and the stirring and degassing are continued; Step 4: Finally, add the curing agent into the vacuum mixer for sufficient degassing and stirring; Step 5: Add the mixture stirred evenly in step 4 into a molding mold for curing and molding, and finally obtain an epoxy resin composite material for aviation drawing molds.

3. The method for preparing the epoxy resin composite material for aviation drawing mold according to claim 2, characterized in that: The stirring time of step 1 is 10 minutes, and the stirring power is 2000-2200W.

4. The method for preparing the epoxy resin composite material for aviation drawing mold according to claim 2, characterized in that: The stirring time of step 2 is 20 minutes, and the stirring power is 2000-2300W.

5. The method for preparing the epoxy resin composite material for aviation drawing mold according to claim 2, characterized in that: The diluent in step 3 is of glycidyl ether type.

6. The method for preparing the epoxy resin composite material for aviation drawing mold according to claim 2, characterized in that: The toughening agent in step 3 is one of dibutyl phthalate, BI7774, and WD-401.

7. The method for preparing the epoxy resin composite material for aviation drawing mold according to claim 2, characterized in that: The curing agent in step 4 is m-phenylenediamine; the stirring and degassing time is 30 minutes; and the stirring power is 2000-2300W.

8. The method for preparing the epoxy resin composite material for aviation drawing mold according to claim 1, characterized in that: Before the molding mold is used in step 5, the pretreatment method includes: cleaning the molding mold; and evenly applying silicone grease release agent on the cleaned mold surface; wherein the cleaning method is: using anhydrous ethanol as a cleaning solvent to clean the mold, and after cleaning, placing the mold in an oven for heating, and the heating temperature is 60 to 70°C.

9. The method for preparing the epoxy resin composite material for aviation drawing mold according to claim 1, characterized in that: In step 5, the curing condition is room temperature curing, and the time is 6-7h.

Images