Preparation method of fiber reinforced nylon composite material plate

Abstract

The invention discloses a preparation method of a fiber reinforced nylon composite material plate, and belongs to the field of composite material plate preparation, and the preparation method comprises the following steps: placing a mold on an electromagnetic vibration table, and fixing; the fiber cloth is laid in a mold according to the content requirement and preheated, the preheating temperature of the mold is 120-130 DEG C, the preheating time is 30 min, and the fiber content is 30-50%; the preparation method comprises the following steps: putting a caprolactam monomer, sodium hydroxide and isocyanate into a glue injection machine according to a proportioning relation, heating and vacuumizing to obtain a mixture; after glue injection is completed, the frequency and time of the electromagnetic vibration table are adjusted, and full impregnation of the fibers is achieved; and after the reaction is completed, demolding to obtain the fiber reinforced nylon composite material plate. The caprolactam monomer can fully flow and permeate in the mold through electromagnetic vibration and vibration frequency adjustment, the impregnation degree of fibers is improved, the porosity of a product is reduced, electromagnetic vibration is introduced in the reaction process, and then the performance of the composite material is improved.

Description

Technical Field

[0001] The invention belongs to a method for preparing a composite material plate, and in particular relates to a method for preparing a fiber-reinforced nylon composite material plate. Background Art

[0002] Composite nylon sheets are divided into two types according to different production processes: extrusion and casting. Among them, casting to prepare fiber-reinforced nylon sheets can achieve the continuity of fibers in the mold, thereby preparing high-performance composite materials. For example, invention CN113696583A2021 discloses a continuous fiber-reinforced MC nylon sheet, a preparation method and a preparation system, using MC nylon as a resin substrate and a continuous fiber ply as a reinforcement skeleton. First, a base film is laid, and then a continuous fiber ply is laid on the base film and preheated, and then the continuous fiber ply is impregnated with MC nylon prepolymer, and finally the impregnated MC nylon prepolymer is heated and cured to prepare a continuous fiber-reinforced MC nylon sheet product. Patent CN101525433A2009 discloses a fiber-reinforced modified reaction injection molded nylon sheet and its preparation process, which uses caprolactam monomer as the basic raw material, adds catalyst, co-catalyst, auxiliary antioxidant, stabilizer, surface treatment agent, etc., and injects it into the high-temperature mold cavity of the pre-set fiber through a reaction injection (RIM) machine, and hot press molding to obtain a reinforced reaction injection molded nylon sheet. However, the main problem of the current casting molding process is that the flow field uniformity of the nylon monomer in the mold is difficult to guarantee, especially when the fiber content is high, it is not easy to penetrate the fiber, which leads to a high porosity of the composite material. The electromagnetic vibration table is a device that uses electromagnetic force to generate vibration, and its basic principle is to use the law of electromagnetic induction and Newton's second law to achieve when. When a wire moves in a magnetic field, according to the law of electromagnetic induction, an induced electromotive force will be generated at both ends of the wire, and the magnitude of this induced electromotive force is proportional to the speed of movement of the wire in the magnetic field. If this induced electromotive force is connected to a resistor, then a current will be generated when moving in the magnetic field, and this current will generate a force opposite to the original direction of movement, which will cause the wire to vibrate. By adjusting the vibration frequency through electromagnetic vibration, the sufficient flow and penetration of caprolactam monomer in the mold can be achieved, thereby improving the impregnation degree of the fiber; at the same time, the introduction of electromagnetic vibration during the reaction process can also adjust the crystallinity of the composite material, thereby improving the performance of the composite material. Summary of the invention

[0003] The purpose of the present invention is to solve the problems of difficulty in ensuring uniformity of nylon monomer flow field and difficulty in fiber penetration, and to propose a method for preparing a fiber-reinforced nylon composite material plate.

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

[0005] A method for preparing a fiber-reinforced nylon composite material plate comprises the following steps:

[0006] 1) Place the mold on the electromagnetic vibration table and fix it;

[0007] 2) Lay the fiber cloth in the mold according to the content requirements and preheat it. The mold preheating temperature is 120-130°C, the preheating time is 30 minutes, and the fiber content is 30-50%;

[0008] 3) putting caprolactam monomer, sodium hydroxide and isocyanate into a glue injection machine according to a ratio, heating and vacuuming to obtain a mixture;

[0009] 4) The mixture is injected into the mold through the mold injection port, the mold is heated according to the set process temperature, and the electromagnetic vibration table vibrates at the set vibration frequency to achieve full flow of the mixture;

[0010] 5) After the glue injection is completed, adjust the frequency and time of the electromagnetic vibration table to achieve full impregnation of the fiber;

[0011] 6) After the reaction is completed, demoulding is performed to obtain a fiber-reinforced nylon composite material sheet.

[0012] The processing method for preparing a fiber-reinforced nylon composite material plate is characterized in that, in step 3), the molar ratio of caprolactam monomer, sodium caprolactam and isocyanate is 100:2:1.0-2.0, the heating temperature of the glue injection machine is 100°C, and vacuum is drawn after the caprolactam monomer is safely melted, the vacuum degree is -0.98MPa, and the vacuum drawing time is 30-45min; then the heating temperature is increased to 130°C to allow the caprolactam monomer to react fully with sodium hydroxide; after the caprolactam monomer and sodium hydroxide react fully, the vacuum drawing is stopped and the plate is put into use.

[0013] As a further description of the above technical solution:

[0014] The processing method for preparing a fiber-reinforced nylon composite material plate is characterized in that, in step 4), the frequency range of the electromagnetic vibration table is 0-10kHz, the length and width of the mold are 200×200mm, and the thickness is 10mm.

[0015] As a further description of the above technical solution:

[0016] The processing method for preparing a fiber-reinforced nylon composite material plate is characterized in that, in step 4), the frequency mode of the electromagnetic vibration table is a cyclic vibration of high frequency first and low frequency later, which continues until the injection of glue is completed.

[0017] As a further description of the above technical solution:

[0018] The processing method for preparing a fiber-reinforced nylon composite material plate is characterized in that in step 4), the mold process temperature is set to 150-180°C.

[0019] As a further description of the above technical solution:

[0020] The processing method for preparing a fiber-reinforced nylon composite material plate is characterized in that, in step 5), after the glue injection is completed, the frequency mode of the electromagnetic vibration table is low-frequency vibration, and the vibration time is 5-10 minutes.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0022] In the present invention, by adjusting the vibration frequency through electromagnetic vibration, the full flow and penetration of the caprolactam monomer in the mold can be achieved, the impregnation degree of the fiber can be improved, and the porosity of the product can be reduced.

[0023] In the present invention, electromagnetic vibration is introduced during the reaction process to adjust the crystallinity of the composite material, thereby improving the performance of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a schematic diagram of the process flow of preparing a fiber-reinforced nylon composite material plate. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] See also Figure 1 , the present invention provides a technical solution:

[0027] Example 1

[0028] A method for preparing a fiber-reinforced nylon composite material plate comprises the following steps:

[0029] 1) Place the mold on the electromagnetic vibration table and fix it;

[0030] 2) Lay the fiber cloth in the mold according to the content requirements and preheat it. The mold preheating temperature is 120-130°C, the preheating time is 30 minutes, and the fiber content is 30-50%;

[0031] 3) putting caprolactam monomer, sodium hydroxide and isocyanate into a glue injection machine according to a ratio, heating and vacuuming to obtain a mixture;

[0032] 4) The mixture is injected into the mold through the mold injection port, the mold is heated according to the set process temperature, and the electromagnetic vibration table vibrates at the set vibration frequency to achieve full flow of the mixture;

[0033] 5) After the glue injection is completed, adjust the frequency and time of the electromagnetic vibration table to achieve full impregnation of the fiber;

[0034] 6) After the reaction is completed, demoulding is performed to obtain a fiber-reinforced nylon composite material sheet.

[0035] In the test, the glass fiber mass content of the fiber-reinforced nylon composite material sheet is 30%. The molar ratio of caprolactam monomer, sodium caprolactam and isocyanate is 100:2:1.0, the heating temperature of the glue injection machine is 100℃, and the vacuum is drawn after the caprolactam monomer is safely melted, the vacuum degree is -0.98MPa, and the vacuum time is 30min; then the heating temperature is raised to 130℃, so that the caprolactam monomer and sodium hydroxide react fully; after the caprolactam monomer and sodium hydroxide react fully, the vacuum is stopped and used. In step 4), the frequency mode of the electromagnetic vibration table is high-frequency and then low-frequency cyclic vibration, the high frequency is 6kHz, the low frequency is 3Hz, the cycle time is 2s, and it continues until the injection is completed. In step 4), the mold process temperature is set to 150℃; in step 5), after the injection is completed, the frequency mode of the electromagnetic vibration table is low-frequency vibration, the low frequency is 1Hz, and the vibration time is 5min. After testing, the tensile strength of the composite material plate is 320MPa, the bending strength is 360MPa, the porosity is 2.5%, and the crystallinity is 56.47%.

[0036] Example 2

[0037] The test procedure is the same as in Example 1.

[0038] The content of glass fiber laying is 40%. The molar ratio of caprolactam monomer, sodium caprolactam and isocyanate is 100:2:1.5, the heating temperature of the glue injection machine is 100℃, and the vacuum is drawn after the caprolactam monomer is safely melted, the vacuum degree is -0.98MPa, and the vacuum drawing time is 40min; then the heating temperature is increased to 130℃, so that the caprolactam monomer and sodium hydroxide react fully; after the caprolactam monomer and sodium hydroxide react fully, stop vacuuming and standby. In step 4), the frequency mode of the electromagnetic vibration table is high-frequency and then low-frequency cyclic vibration, the high frequency is 8kHz, the low frequency is 4Hz, the cycle time is 2s, and it continues until the glue injection is completed. In step 4), the mold process temperature is set to 170℃; in step 5), after the glue injection is completed, the frequency mode of the electromagnetic vibration table is low-frequency vibration, the low frequency is 1.5Hz, and the vibration time is 8min. After testing, the tensile strength of the composite material sheet is 432MPa, the bending strength is 475MPa, the porosity is 1.5%, and the crystallinity is 58.95%.

[0039] Example 3

[0040] The test procedure is the same as in Example 1.

[0041] The content of glass fiber laying is 50%. The molar ratio of caprolactam monomer, sodium caprolactam and isocyanate is 100:2:2, the heating temperature of the glue injection machine is 100℃, and the vacuum is drawn after the caprolactam monomer is safely melted, the vacuum degree is -0.98MPa, and the vacuum drawing time is 45min; then the heating temperature is increased to 130℃, so that the caprolactam monomer and sodium hydroxide react fully; after the caprolactam monomer and sodium hydroxide react fully, stop vacuuming and standby. In step 4), the frequency mode of the electromagnetic vibration table is high-frequency and then low-frequency cyclic vibration, the high frequency is 10kHz, the low frequency is 5Hz, the cycle time is 2s, and it continues until the glue injection is completed. In step 4), the mold process temperature is set to 180℃; in step 5), after the glue injection is completed, the frequency mode of the electromagnetic vibration table is low-frequency vibration, the low frequency is 2Hz, and the vibration time is 10min. After testing, the tensile strength of the composite material plate is 510MPa, the bending strength is 625MPa, the porosity is 0.8%, and the crystallinity is 65.68%.

[0042] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a fiber-reinforced nylon composite material sheet, comprising the following steps: 1) Place the mold on the electromagnetic vibration table and fix it; 2) The fiber cloth is laid into the mold according to the content requirements and preheated. The mold preheating temperature is 120-130°C, the preheating time is 30 minutes, and the fiber content is 30-50%; 3) adding caprolactam monomer, sodium hydroxide and isocyanate into a glue injection machine according to a ratio, heating and vacuuming the mixture to obtain a mixture; 4) The mixture is injected into the mold through the mold injection port, the mold is heated according to the set process temperature, and the electromagnetic vibration table vibrates at the set vibration frequency to achieve full flow of the mixture; 5) After the glue injection is completed, adjust the frequency and time of the electromagnetic vibration table to achieve full impregnation of the fiber; 6) After the reaction is completed, demoulding is performed to obtain a fiber-reinforced nylon composite material sheet.

2. The method for preparing a fiber-reinforced nylon composite material sheet according to claim 1, characterized in that: In step 4), the frequency range of the electromagnetic vibration table is 0-10kHz, the length and width of the mold are 200×200mm, and the thickness is 10mm.

3. A processing method for preparing a fiber-reinforced nylon composite material sheet according to claim 1-2, characterized in that: In step 3), the molar ratio of caprolactam monomer, sodium caprolactam and isocyanate is 100:2:1.0-2.0, the heating temperature of the glue injection machine is 100°C, and vacuum is drawn after the caprolactam monomer is safely melted, the vacuum degree is -0.98MPa, and the vacuum drawing time is 30-45min; then the heating temperature is increased to 130°C to allow the caprolactam monomer to react fully with the sodium hydroxide; after the caprolactam monomer and the sodium hydroxide react fully, the vacuum drawing is stopped and the machine is set aside.

4. A processing method for preparing a fiber-reinforced nylon composite material sheet according to claims 1-3, characterized in that: In step 4), the frequency mode of the electromagnetic vibration table is a cyclic vibration of high frequency first and low frequency later, the frequency of the high frequency is 6-10kHz, the frequency of the low frequency is 3-5Hz, the cycle time is 2s, and it continues until the injection is completed.

5. A processing method for preparing a fiber-reinforced nylon composite material sheet according to claims 1-4, characterized in that: In step 4), the mold process temperature is set to 150-180°C.

6. A method for preparing a fiber-reinforced nylon composite material sheet according to claims 1-5, characterized in that: In step 5), after the glue injection is completed, the frequency mode of the electromagnetic vibration table is low-frequency vibration, the low-frequency frequency is 1-2 Hz, and the vibration time is 5-10 minutes.

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