In-mold forming process of carbon fiber composite product based on epoxy foaming core material

Abstract

The invention discloses an in-mold forming process of a carbon fiber composite product based on an epoxy foaming core material, which comprises the following steps: putting the epoxy core material into a mold for heating and foaming to obtain the epoxy foaming core material; according to the mechanical design requirement, carbon fiber dry cloth is adopted for laying to wrap the epoxy foaming core material, and a prefabricated product is obtained; placing the prefabricated product in a mold cavity, closing and locking the mold, and vacuumizing to enable the mold cavity to be in a negative pressure state; and injecting the two-component epoxy resin glue solution into the mold cavity through mixed glue injection equipment, heating, curing, cooling, balancing the pressure inside and outside the mold, and demolding to obtain the carbon fiber composite product. The carbon fiber composite product with high appearance quality can be prepared, and the molding process is matched with the structural strength of the internal epoxy foaming core material, so that the product is good in interface bonding property and high in curing efficiency, and industrial batch production can be met.

Description

Technical Field

[0001] The invention relates to the technical field of composite material molding, and in particular to an in-mold molding process of a carbon fiber composite product based on an epoxy foam core material. Background Art

[0002] Carbon fiber composite materials have both strong performance and light weight, and are widely used in products such as automobiles, ships, aircraft and sports equipment. At present, the weight reduction scheme of carbon fiber composite products based on epoxy resin basically adopts conventional sandwich materials, such as PVC, PMI, PET, PU, ​​honeycomb paper, balsa wood, etc. The above lightweight materials have their own advantages, disadvantages and limitations. The molding processes on the market mainly include hand lay-up process, prepreg molding process, vacuum bag oven process, autoclave process, RTM, HP-RTM, thermal expansion molding process HEM, etc. The existing lightweight sandwich materials and molding processes have their own advantages, disadvantages and limitations. However, for carbon fiber composites based on epoxy foam core materials, the interface bonding between carbon fiber prepreg and epoxy foam core materials is poor, there are many gaps, and the press molding process is easy to cause structural damage to the epoxy foam core material, thereby seriously reducing the product performance, and the production efficiency is low, and it is difficult to ensure the quality rate and efficiency. Summary of the invention

[0003] The present invention provides an in-mold molding process for a carbon fiber composite product based on an epoxy foam core material, so as to solve the technical problem that the current molding cannot meet the product performance requirements of the carbon fiber composite product based on the epoxy foam core material.

[0004] In order to solve the above technical problems, in a first aspect, the present invention provides an in-mold molding process for a carbon fiber composite product based on an epoxy foam core material, comprising:

[0005] Putting the epoxy core material into a mold for heating and foaming to obtain an epoxy foam core material;

[0006] According to mechanical design requirements, a carbon fiber dry cloth is laid to wrap the epoxy foam core material to obtain a preformed product;

[0007] Place the preform in the mold cavity, close and lock the mold, and evacuate the mold cavity to a negative pressure state;

[0008] The two-component epoxy resin glue is injected into the above-mentioned mold cavity through a mixed injection device, heated and cured, cooled, the pressure inside and outside the mold is balanced, and demolding is performed to obtain a carbon fiber composite product, wherein the injection pressure is 0.11MPa~15MPa, the curing temperature is 25℃~150℃, the curing maintenance time is 1min~24h, and the cooling temperature range is 25℃~100℃.

[0009] In some embodiments, the step of placing the epoxy core material into a mold for heating and foaming to obtain the epoxy foamed core material comprises:

[0010] Putting the epoxy core material into the mold, and then sending the mold into the press to close the mold and lock the mold, heating the mold so that the epoxy core material is heated and foamed into the epoxy foam core material, the heating temperature is 120° C. to 150° C., and the heating time is 10 min to 60 min;

[0011] After the mold is cooled, open the mold and take out the epoxy foam core material.

[0012] In some embodiments, the density of the epoxy foam core material is 0.015 g / cm 3 ~0.6g / cm 3 .

[0013] In some embodiments, the temperature of the mold is cooled to no greater than 80°C.

[0014] In some embodiments, the negative pressure state is the mold cavity air pressure = 0.1Pa ~ 100KPa.

[0015] In some embodiments, when the curing temperature is 150° C., the curing time is 1 min to 10 min.

[0016] In some embodiments, the ply angle of the carbon fiber dry cloth includes one or more of 0°, 45°, -45° and 90°.

[0017] In some embodiments, the density of the epoxy core material is 0.3 g / cm 3 ~1.15g / cm 3 .

[0018] Optionally, the epoxy core material is selected from the epoxy core material EFC series K102, K103, K119, K126, K127, K127X, K128, K129, K130, K132, K138, K140, K141, K143, K150, K520, K521, K531, K550, K560, K561, K601, K615, K618, K 620, K621, K622, K630, K660, K680, K683, K806, K810, K812, K812-3, K812-5, K813, K815, K820, K830, K835, K836, K839, K870, K880, K890, K930, K950, K951, K970, K971, K972, K973, K974, or K975.

[0019] In some embodiments, the two-component epoxy resin glue includes component A epoxy resin and component B amine curing agent, wherein the viscosity range of component A epoxy resin at 25°C is 500-1000cps, and the epoxy equivalent range is 150-200g / eq; the annual range of component B amine curing agent at 25°C is 30-1000cps, and the active hydrogen equivalent is 25-150g / eq; the mass ratio of component A epoxy resin to component B amine curing agent is 1:(1.2-0.15).

[0020] Optionally, the two-component epoxy resin adhesive is selected from ML-5419AB and AM-8931AB of Huibo New Materials, and ARALDITE LY 3585 / ARADUR 3834, ARALDITE LY 3508 / ARADUR 3475 and ARALDITE LY1572 / ARADUR 22962 of Huntsman.

[0021] In some of the embodiments, the carbon fiber dry cloth has a fiber tow range of 1000-24000, a tensile strength of 3000-7000 MPa, and a tensile modulus of 200-400 GPa.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] 1. The process of first applying negative pressure and then applying pressure during the preparation process of the present invention can effectively remove the air between the composite layers to obtain a dense product, thereby being able to produce a carbon fiber composite product with high appearance quality and eliminating the need for post-processing processes for the appearance of the product (such as surface polishing processes); and the epoxy core material can be arbitrarily shaped and foamed controllably, which can meet the product design requirements of different appearance shapes, especially the product design requirements of certain local dimensions less than 1 mm thickness or sharp corners, overcoming the problem that the existing foaming CNC machining process cannot achieve core material accuracy.

[0024] 2. The molding process of the present invention matches the structural strength of the internal epoxy foam core material, and causes little damage to the structure of the epoxy foam core material. It only requires glue injection and heating and curing in the mold cavity, and no pressing force is required by a press. This overcomes the problem of traditional press molding processes that, due to excessive instantaneous pressure, lead to fiber layer slippage, wrinkles, convex and concave deformation at the interface between the core material and the composite material, which in turn leads to unstable strength of batch products.

[0025] 3. The product of the present invention has good interface bonding. The epoxy foam core material is wrapped with carbon fiber dry cloth, and then resin glue is injected into the mold cavity to infiltrate the carbon fiber dry cloth in the mold cavity and fill the mold cavity, so that it has better interface bonding performance with the epoxy foam core material, overcoming the problems of lack of glue and poor interface bonding in the traditional process of combining carbon fiber prepreg with epoxy foam core material.

[0026] 4. The present invention adopts the Heat Expansion-Resin Transfer Molding (HE-RTM) process with high curing efficiency. Compared with the traditional press molding process which requires a curing time of 0.5h to 24h, the present invention can achieve a rapid curing effect within 10min, meeting the requirements of industrial high-beat batch production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a physical schematic diagram of an epoxy foam core material and a carbon fiber composite product corresponding to the product 1 shown in an embodiment of the present invention;

[0028] Figure 2 This is a physical schematic diagram of an epoxy foam core material and a carbon fiber composite product corresponding to the product 2 shown in an embodiment of the present invention;

[0029] Figure 3 This is a physical schematic diagram of a carbon fiber composite product corresponding to product 3 shown in an embodiment of the present invention;

[0030] Figure 4 This is a physical schematic diagram of a carbon fiber composite product corresponding to the product 4 shown in the embodiment of the present invention;

[0031] Figure 5 This is a physical schematic diagram of a carbon fiber composite product corresponding to the product 5 shown in the embodiment of the present invention;

[0032] Figure 6 It is a physical schematic diagram of a carbon fiber composite product corresponding to the product 6 shown in the embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0034] As used herein, the term "prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0035] When amount, concentration or other value or parameter is expressed as range, preferred range or a series of upper preferred value and lower preferred value limit range, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when disclosing range "1 to 5", described range should be interpreted as including range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. When numerical range is described in this article, unless otherwise stated, the range is intended to include its end value and all integers and fractions within the range.

[0036] In addition, the indefinite articles "a" and "an" before the elements or components of the present invention have no restrictions on the quantity requirements (i.e. the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the number is obviously intended to be in the singular form.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0038] Some raw materials and process parameters of Examples 1 to 5 of the present invention and Comparative Example 1 are shown in Table 1 below:

[0039] Table 1 Raw materials and process parameters of Examples 1 to 5 and Comparative Example 1

[0040]

[0041]

[0042] Example 1

[0043] The epoxy core material K102 (density 0.3g / cm 3 , 1atm and 150°C free foaming ratio of 4) into the mold, and then send the mold into the press to close the mold and lock the mold, heat the mold so that the epoxy core material is heated and foamed into the epoxy foam core material, the heating temperature is 140°C, and the heating time is 20min; after the mold is cooled to no more than 80°C, the mold is opened to take out the epoxy foam core material (density is 0.15g / cm 3 );

[0044] According to the mechanical design requirements, a carbon fiber dry cloth is laid to wrap the epoxy foam core material to obtain a preformed product, wherein the fiber tow range of the carbon fiber dry cloth is 3000, the tensile strength is 3530 MPa, and the tensile modulus is 230 GPa;

[0045] Place the preform in the mold cavity, close and lock the mold, and evacuate the mold cavity to a pressure of 0.1 Pa;

[0046] Inject epoxy resin glue ML-5419AB into the mold cavity under pressure, heat and cure, cool, vent to ambient atmospheric pressure, demould, and obtain a carbon fiber composite product (corresponding to Figure 1 ), where the pressing pressure is 0.11MPa, the curing temperature is 25°C, and the curing time is 24h.

[0047] Example 2

[0048] The epoxy core material K127 (density 0.35g / cm 3 , the free foaming ratio at 1 atm and 150°C is 12.5) is placed in the mold, and then the mold is sent to the press to close the mold and lock the mold, and the mold is heated to make the epoxy core material foamed into the epoxy foam core material by heating. The heating temperature is 145°C and the heating time is 20min. After the mold is cooled to no more than 80°C, the mold is opened to take out the epoxy foam core material (density is 0.11g / cm 3 );

[0049] According to the mechanical design requirements, a carbon fiber dry cloth is laid to wrap the epoxy foam core material to obtain a preformed product, wherein the fiber tow range of the carbon fiber dry cloth is 3000, the tensile strength is 3530 MPa, and the tensile modulus is 230 GPa;

[0050] Place the preform in the mold cavity, close and lock the mold, and evacuate the mold cavity to a pressure of 1Kpa;

[0051] Inject epoxy resin glue ARALDITE LY1572 / ARADUR 22962 into the mold cavity under pressure, heat and cure, cool, vent to ambient atmospheric pressure, demold, and obtain a carbon fiber composite product (corresponding to Figure 2 ), where the pressing pressure is 1MPa, the curing temperature is 120°C, and the curing time is 0.3h.

[0052] Example 3

[0053] The epoxy core material K550 (density 0.6g / cm 3, the free foaming ratio at 1 atm and 150°C is 0) is placed in the mold, and then the mold is sent to the press to close the mold and lock the mold, and the mold is heated to make the epoxy core material foamed into the epoxy foam core material by heating. The heating temperature is 150°C and the heating time is 15min. After the mold is cooled to no more than 80°C, the mold is opened to take out the epoxy foam core material (density is 0.55g / cm 3 );

[0054] According to the mechanical design requirements, a carbon fiber dry cloth is laid to wrap the epoxy foam core material to obtain a preformed product, wherein the fiber tow range of the carbon fiber dry cloth is 24000, the tensile strength is 7000 MPa, and the tensile modulus is 294 GPa;

[0055] Place the preform in the mold cavity, close and lock the mold, and evacuate the mold cavity to a pressure of 10Kpa;

[0056] Inject epoxy resin glue ARALDITE LY3508 / ARADUR 3475 into the mold cavity under pressure, heat and cure, cool, vent to ambient atmospheric pressure, demold, and obtain a carbon fiber composite product (corresponding to Figure 3 ), where the pressing pressure is 10MPa, the curing temperature is 150°C, and the curing time is 1min.

[0057] Example 4

[0058] The epoxy core material K630 (density 0.86g / cm 3 , the free foaming ratio at 1 atm and 150°C is 110) is placed in the mold, and then the mold is sent to the press to close the mold and lock the mold, and the mold is heated to make the epoxy core material foamed into the epoxy foam core material by heating. The heating temperature is 120°C and the heating time is 50min. After the mold is cooled to no more than 80°C, the mold is opened to take out the epoxy foam core material (density is 0.03g / cm 3 );

[0059] According to the mechanical design requirements, a carbon fiber dry cloth is laid to wrap the epoxy foam core material to obtain a preformed product, wherein the fiber tow range of the carbon fiber dry cloth is 12000, the tensile strength is 6370 MPa, and the tensile modulus is 294 GPa;

[0060] Place the preform in the mold cavity, close the mold, and vacuum the mold cavity to a pressure of 100Kpa;

[0061] Inject epoxy resin glue ML-5419AB into the mold cavity under pressure, heat and cure, cool, vent to ambient atmospheric pressure, demould, and obtain a carbon fiber composite product (corresponding to Figure 4 ), where the pressing pressure is 0.2MPa, the curing temperature is 150°C, and the curing time is 15min.

[0062] Example 5

[0063] The epoxy core material K971 (density 1.03g / cm 3 , the free foaming ratio at 1 atm and 150°C is 52.5) ​​is placed in the mold, and then the mold is sent to the press to close the mold and lock the mold, and the mold is heated to make the epoxy core material foamed into the epoxy foam core material by heating. The heating temperature is 150°C and the heating time is 10 minutes. After the mold is cooled to no more than 80°C, the mold is opened to take out the epoxy foam core material (density is 0.07g / cm 3 );

[0064] According to the mechanical design requirements, a carbon fiber dry cloth is laid to wrap the epoxy foam core material to obtain a preformed product, wherein the fiber tow range of the carbon fiber dry cloth is 3000, the tensile strength is 3530 MPa, and the tensile modulus is 230 GPa;

[0065] Place the preform in the mold cavity, close and lock the mold, and evacuate the mold cavity to a pressure of 1KPa;

[0066] Inject epoxy resin glue ARALDITE LY1572 / ARADUR 22962 into the mold cavity under pressure, heat and cure, cool, vent to ambient atmospheric pressure, demold, and obtain a carbon fiber composite product (corresponding to Figure 5 ), where the pressing pressure is 0.9MPa, the curing temperature is 130°C, and the curing time is 20min.

[0067] Comparative Example 1

[0068] The difference from Example 5 is that carbon fiber prepreg is used instead of carbon fiber dry cloth, and resin glue is no longer injected into the mold cavity, but the traditional molding process is used to obtain a carbon fiber composite product (corresponding to Figure 6 ).

[0069] like Figures 1 to 5 As shown, the carbon fiber composite products corresponding to Examples 1 to 5 are respectively compared with Figure 6 The carbon fiber composite product of Comparative Example 1 shown in the figure is made of carbon fiber prepreg cloth combined with traditional molding process, and the product surface has obvious glue deficiency and poor interface bonding. Examples 1 to 5 of the present invention use carbon fiber dry cloth combined with HEM process to obtain carbon fiber composite products with high appearance quality, little damage to the core material structure and good interface bonding.

[0070] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. An in-mold molding process for carbon fiber composite products based on epoxy foam core material, characterized in that: include: Putting the epoxy core material into a mold for heating and foaming to obtain an epoxy foam core material; According to mechanical design requirements, a carbon fiber dry cloth is laid to wrap the epoxy foam core material to obtain a preformed product; Place the preform in the mold cavity, close and lock the mold, and evacuate the mold cavity to a negative pressure state; The two-component epoxy resin glue is injected into the above-mentioned mold cavity through a mixed injection device, heated and cured, cooled, the pressure inside and outside the mold is balanced, and demolding is performed to obtain a carbon fiber composite product, wherein the injection pressure is 0.11MPa~15MPa, the curing temperature is 25℃~150℃, the curing maintenance time is 1min~24h, and the cooling temperature range is 25℃~100℃.

2. The in-mold forming process of the carbon fiber composite product based on epoxy foam core material according to claim 1, characterized in that: The step of placing the epoxy core material into a mold for heating and foaming to obtain the epoxy foamed core material comprises: Putting the epoxy core material into the mold, and then sending the mold into the press to close the mold and lock the mold, heating the mold so that the epoxy core material is heated and foamed into the epoxy foam core material, the heating temperature is 140° C. to 150° C., and the heating time is 10 min to 30 min; After the mold is cooled, open the mold and take out the epoxy foam core material.

3. The in-mold forming process of the carbon fiber composite product based on epoxy foam core material according to claim 1 or 2, characterized in that: The density of the epoxy foam core material is 0.015 g / cm 3 ~0.6g / cm 3 .

4. The in-mold forming process of the carbon fiber composite product based on epoxy foam core material according to claim 2, characterized in that: The temperature of the mold is cooled to no more than 80°C.

5. The in-mold forming process of the carbon fiber composite product based on epoxy foam core material according to claim 1, characterized in that: The density of the epoxy core material is 0.3 g / cm 3 ~1.15g / cm 3 .

6. The in-mold forming process of the carbon fiber composite product based on epoxy foam core material according to claim 1, characterized in that: The negative pressure state is the mold cavity air pressure = 0.1Pa ~ 100KPa.

7. The in-mold forming process of the carbon fiber composite product based on epoxy foam core material according to claim 1, characterized in that: When the curing temperature is 150° C., the curing time is 1 min to 10 min.

8. The in-mold forming process of the carbon fiber composite product based on epoxy foam core material according to claim 1, characterized in that: The ply angle of the carbon fiber dry cloth includes one or more of 0°, 45°, -45° and 90°.

9. The in-mold forming process of the carbon fiber composite product based on epoxy foam core material according to claim 1, characterized in that: The two-component epoxy resin glue comprises an epoxy resin as component A and an amine curing agent as component B, wherein the viscosity of the epoxy resin as component A at 25°C ranges from 500 to 1000 cps, and the epoxy equivalent ranges from 150 to 200 g / eq; the viscosity of the amine curing agent as component B at 25°C ranges from 30 to 1000 cps, and the active hydrogen equivalent is from 25 to 150 g / eq; the mass ratio of the epoxy resin as component A to the amine curing agent as component B is 1:(1.2 to 0.15).

10. The in-mold forming process of the carbon fiber composite product based on epoxy foam core material according to claim 1, characterized in that: The fiber tow of the carbon fiber dry cloth ranges from 1000 to 24000, the tensile strength is from 3000 to 7000 MPa, and the tensile modulus is from 200 to 400 GPa.

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