Fiber reinforced nylon composite material and preparation method thereof

Abstract

The invention provides a preparation method of a fiber-reinforced nylon composite material and the fiber-reinforced nylon composite material prepared by the preparation method.The preparation method comprises the steps that S1, caprolactam is divided into a component A and a component B, and the caprolactam is heated, melted and dehydrated; s2, mixing the component A with a catalyst to obtain a component A1, mixing the component B with an activator to obtain a component B1, and dehydrating the component A1 and the component B1; and S3, mixing the component A1 and the component B1, injecting the mixture into a mold cavity in which a fiber reinforcement is preset at high pressure, and carrying out pressure-maintaining curing molding under the conditions that the pressure of high-pressure injection is 50-160 bar, the pressure of pressure maintaining is 1200-2400 T, the time is 3-8 minutes, and the temperature of the mold cavity is 140-180 DEG C. The nylon composite material prepared by the invention can fully infiltrate fibers, and meanwhile, the volume shrinkage of the nylon composite material is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of thermoplastic composites, and particularly relates to a fiber-reinforced nylon composite material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of new energy vehicles and energy storage industries, the demand for lightweight, high-strength, high-temperature-resistant and recyclable materials is increasingly urgent. Traditional metal materials are difficult to meet the lightweight requirements of battery boxes, motor supports and other components due to their high density and complex processing. Although thermosetting composites have high strength, their non-recyclability is contrary to the sustainable development concept of new energy vehicles. Thermoplastic composites gradually become an important direction to replace traditional metals and thermosetting materials due to their excellent mechanical properties, recyclability and high molding efficiency.

[0003] In recent years, nylon thermoplastic materials formed by anionic ring-opening polymerization (AROP) have attracted much attention. The materials can be in-situ formed through rapid polymerization reaction, and the products can be repeatedly melt-processed. However, the existing production process of fiber-reinforced nylon composites has the technical problems that the nylon cannot fully infiltrate the fibers and the fiber-reinforced nylon composite material has a large volume shrinkage. SUMMARY

[0004] In order to solve the above technical problems, the purpose of the present application is to provide a fiber-reinforced nylon composite material and a preparation method thereof, so as to realize that the nylon fully infiltrates the fibers and reduce the volume shrinkage of the nylon composite material.

[0005] The present application provides a preparation method of a fiber-reinforced nylon composite material, which comprises the following steps: S1. Dividing caprolactam into component A and component B, and heating and melting, dehydrating caprolactam; S2. Mixing the component A with a catalyst to obtain component A1, and mixing the component B with an activator to obtain component B1, and then dehydrating component A1 and component B1; S3. After mixing component A1 and component B1, high-pressure injection is performed into a mold cavity preloaded with a fiber reinforcement, pressure curing is performed, the pressure of the high-pressure injection is 50-160 bar, the pressure of the pressure curing is 1200T-2400T, the time is 3-8 minutes, and the temperature of the mold cavity is 140-180℃.

[0006] The application provides a preparation method of a fiber-reinforced nylon composite material, which realizes full infiltration of nylon into fibers and reduces volume shrinkage of the nylon composite material by optimizing an injection molding process.

[0007] Preferably, in the S1, the catalyst comprises at least one of metallic sodium, sodium hydroxide, potassium hydroxide and sodium methoxide.

[0008] Preferably, in the S1, the activator comprises at least one of toluene diisocyanate, diphenylmethane diisocyanate and polymethylene polyisocyanate.

[0009] Preferably, in the S1, the specific dehydration method is vacuum dehydration, the vacuum degree is less than or equal to -0.095 MPa, and the vacuum dehydration time is 30-45 min.

[0010] The specific method of dehydration in the S1 is vacuum dehydration, the vacuum degree is ≤-0.095 Mpa, and the vacuum dehydration time is 30-45 min. The dehydration is the first vacuum dehydration of the molten caprolactam raw material, which can remove >95% of the free water in the caprolactam raw material, reduces the side reaction, and improves the polymerization degree of nylon.

[0011] Preferably, in the S2, the specific method of dehydration is vacuum dehydration, the vacuum degree is ≤-0.095 Mpa, and the vacuum dehydration time is 40-60 min.

[0012] The specific method of dehydration in the S2 is vacuum dehydration, the vacuum degree is ≤-0.095 Mpa, and the vacuum dehydration time is 40-60 min. After the catalyst and the activator are added, the second vacuum dehydration is performed, which can further remove the free water in the raw material, further reduces the side reaction, and further improves the polymerization degree of nylon.

[0013] Preferably, in the S3, the pressure of the high-pressure injection is 90-120 bar, for example, it can be 90 bar, 100 bar, 110 bar, or 120 bar, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0014] In the S3, the pressure of the high-pressure injection is 90-120 bar. In this range, the caprolactam melt can further fully infiltrate the fiber, increase the interface contact area of the nylon resin formed by polymerization and the fiber, reduce the porosity and defects, thereby improving the interface bonding force, further avoiding the displacement or local compression damage of the fiber preform caused by excessively high pressure, and further improving the comprehensive mechanical properties of nylon.

[0015] Preferably, in the S3, the pressure of the pressure holding is 1200T-2000T, and the time is 3-6 min.

[0016] In the S3, the pressure of the pressure holding is 1200T-2000T, and the time is 3-6 min. In this range of high-pressure pressure holding pressure and time, the material can be compacted, the density of the fiber-reinforced nylon composite material is improved, and the wettability of the caprolactam melt to the fiber is improved, thereby reducing the overall shrinkage of the fiber-reinforced nylon composite material. After the fiber reinforcement is injected into the mold cavity, the porosity of the fiber reinforcement is <0.5%.

[0017] Preferably, in the S3, the temperature of the mold cavity is 150-170°C, for example, it can be 155°C, 160°C, or 170°C, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0018] In the S3, the temperature of the mold cavity is 140-170℃. In this range, the polymerization reaction is more complete, the late shrinkage is reduced, the melt viscosity is further reduced, the filling and pressure maintaining effects are improved, and the material degradation, hole defects and intensified side reactions caused by excessively high temperature are further avoided.

[0019] Preferably, in the S3, the temperature for mixing the component A1 and the component B1 is 100-150℃, for example, it can be 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0020] In the S3, the temperature for mixing the component A1 and the component B1 is 95-125℃, which can ensure that the viscosity of the mixture of the component A1 and the component B1 is suitable for high-pressure injection and mold filling, and can also avoid the mixture from being polymerized too early in the mold cavity where the pre-placed fiber reinforcement is not injected, thereby reducing the wettability of the melt to the fiber.

[0021] The application provides a fiber reinforced nylon composite material prepared by the above preparation method. DETAILED DESCRIPTION

[0022] In order for those skilled in the art to better understand the technical solutions in the application, the technical solutions of the application will be described clearly and completely below in combination with the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the application.

[0023] Embodiment 1 The preparation method of the fiber reinforced nylon composite material in this embodiment is as follows: S1. 100 parts by mass of caprolactam raw materials were evenly placed in A and B melting tanks, respectively, and were melted and stirred at 125℃ (the stirring speed was 80 rpm). The first vacuum drying was performed by a vacuum pump built in the melting tank, the vacuum degree was <-0.098 Mpa, and the duration was 45 min to remove the free water in the raw materials.

[0024] S2. 0.2% parts by mass of sodium hydroxide was added to the A tank, and 0.3% parts by mass of hexamethylene diisocyanate (HDI) was added to the B tank. After stirring and mixing, the second vacuum drying was performed, the vacuum degree was <-0.098 Mpa, and the duration was 50 min to further remove the free water in the raw materials.

[0025] S3. The molten bodies in tanks A and B after dehydration treatment are transferred to separate pouring tanks (exemplarily, the temperature is 125°C), and are delivered to a mixing head through a high-pressure metering pump (the pressure is 60 bar). The mixing head injection pressure is 100 bar. The components in tanks A and B are uniformly mixed in a mold cavity. The mixing temperature (achieved by controlling the temperature of the pouring tank) is controlled at 110°C. The mixed glue is injected into the mold cavity (the cavity of the mold) of the pre-placed glass fiber reinforcement through the mold flow channel, to form a caprolactam-glass fiber composite system. The volume fraction of glass fiber in the caprolactam-glass fiber composite system is 65%. The mold temperature is set to 170°C. Pressure polymerization curing is performed. The pressure of pressure retention is 1800T. The time of pressure retention is 5 minutes. After the mold is opened, the fiber-reinforced nylon composite material is demolded.

[0026] After the pre-placed fiber reinforcement is injected into the mold cavity, the porosity of the fiber reinforcement is <0.5%.

[0027] Example 2 The preparation method of the fiber-reinforced nylon composite material in this example is the same as that in Example 1, except that the mixing head injection pressure in step S3 is 160 bar.

[0028] Example 3 The preparation method of the fiber-reinforced nylon composite material in this example is the same as that in Example 1, except that the mixing head injection pressure in step S3 is 50 bar.

[0029] Example 4 The preparation method of the fiber-reinforced nylon composite material in this example is the same as that in Example 1, except that the mixing head injection pressure in step S3 is 60 bar.

[0030] Example 5 The preparation method of the fiber-reinforced nylon composite material in this example is the same as that in Example 1, except that the mixing head injection pressure in step S3 is 80 bar.

[0031] Example 6 The preparation method of the fiber-reinforced nylon composite material in this example is the same as that in Example 1, except that the mixing head injection pressure in step S3 is 90 bar.

[0032] Example 7 The preparation method of the fiber-reinforced nylon composite material in this example is the same as that in Example 1, except that the mixing head injection pressure in step S3 is 120 bar.

[0033] Example 8 The preparation method of the fiber-reinforced nylon composite material in this example is the same as that in Example 1, except that the mixing head injection pressure in step S3 is 130 bar.

[0034] Example 9 The preparation method of the fiber reinforced nylon composite of the present example is the same as example 1 except that the injection pressure of the mixing head in step S3 is 150 bar.

[0035] Comparative example 1 The preparation method of the fiber reinforced nylon composite of the present example is the same as example 1 except that the injection pressure of the mixing head in step S3 is 40 bar.

[0036] Comparative example 2 The preparation method of the fiber reinforced nylon composite of the present example is the same as example 1 except that the injection pressure of the mixing head in step S3 is 190 bar.

[0037] Example 10 The preparation method of the fiber reinforced nylon composite of the present example is the same as example 1 except that the holding pressure in step S3 is 1400T.

[0038] Example 11 The preparation method of the fiber reinforced nylon composite of the present example is the same as example 1 except that the holding pressure in step S3 is 1200T.

[0039] Example 12 The preparation method of the fiber reinforced nylon composite of the present example is the same as example 1 except that the holding pressure in step S3 is 1600T.

[0040] Example 13 The preparation method of the fiber reinforced nylon composite of the present example is the same as example 1 except that the holding pressure in step S3 is 1700T.

[0041] Example 14 The preparation method of the fiber reinforced nylon composite of the present example is the same as example 1 except that the holding pressure in step S3 is 2000T.

[0042] Example 15 The preparation method of the fiber reinforced nylon composite of the present example is the same as example 1 except that the holding pressure in step S3 is 2200T.

[0043] Example 16 The preparation method of the fiber reinforced nylon composite of the present example is the same as example 1 except that the holding pressure in step S3 is 2400T.

[0044] Comparative example 3 The preparation method of the fiber reinforced nylon composite of the present example is the same as example 1 except that the holding pressure in step S3 is 1100T.

[0045] Comparative example 4 The preparation method of the fiber reinforced nylon composite material of the present example is the same as example 1 except that the pressure of step S3 is 2500T.

[0046] Example 17 The preparation method of the fiber reinforced nylon composite material of the present example is the same as example 1 except that the pressure of step S3 is 2500T.

[0047] Example 18 The preparation method of the fiber reinforced nylon composite material of the present example is the same as example 1 except that the pressure of step S3 is 2500T.

[0048] Example 19 The preparation method of the fiber reinforced nylon composite material of the present example is the same as example 1 except that the pressure of step S3 is 2500T.

[0049] Example 20 The preparation method of the fiber reinforced nylon composite material of the present example is the same as example 1 except that the pressure of step S3 is 2500T.

[0050] Example 21 The preparation method of the fiber reinforced nylon composite material of the present example is the same as example 1 except that the pressure of step S3 is 2500T.

[0051] Comparative Example 5 The preparation method of the fiber reinforced nylon composite material of the present example is the same as example 1 except that the pressure of step S3 is 2500T.

[0052] Comparative Example 6 The preparation method of the fiber reinforced nylon composite material of the present example is the same as example 1 except that the pressure of step S3 is 2500T.

[0053] Example 22 The preparation method of the fiber reinforced nylon composite material of the present example is the same as example 1 except that the pressure of step S3 is 2500T.

[0054] Example 23 The preparation method of the fiber reinforced nylon composite material of the present example is the same as example 1 except that the pressure of step S3 is 2500T.

[0055] Example 24 The preparation method of the fiber reinforced nylon composite material of the present example is the same as example 1 except that the pressure of step S3 is 2500T.

[0056] Example 25 The preparation method of the fiber reinforced nylon composite of this example is the same as example 1 except that the temperature of the mold cavity in step S3 is 180°C.

[0057] Comparative example 7 The preparation method of the fiber reinforced nylon composite of this example is the same as example 1 except that the temperature of the mold cavity in step S3 is 190°C.

[0058] Comparative example 8 The preparation method of the fiber reinforced nylon composite of this example is the same as example 1 except that the temperature of the mold cavity in step S3 is 130°C.

[0059] Example 26 The preparation method of the fiber reinforced nylon composite of this example is the same as example 1 except that the mixing temperature in step S3 is controlled at 100°C.

[0060] Example 27 The preparation method of the fiber reinforced nylon composite of this example is the same as example 1 except that the mixing temperature in step S3 is controlled at 105°C.

[0061] Example 28 The preparation method of the fiber reinforced nylon composite of this example is the same as example 1 except that the mixing temperature in step S3 is controlled at 115°C.

[0062] Example 29 The preparation method of the fiber reinforced nylon composite of this example is the same as example 1 except that the mixing temperature in step S3 is controlled at 125°C.

[0063] Example 30 The preparation method of the fiber reinforced nylon composite of this example is the same as example 1 except that the mixing temperature in step S3 is controlled at 140°C.

[0064] Example 31 The preparation method of the fiber reinforced nylon composite of this example is the same as example 1 except that the mixing temperature in step S3 is controlled at 150°C.

[0065] Comparative example 9 The preparation method of the fiber reinforced nylon composite of this example is the same as example 1 except that the mixing temperature in step S3 is controlled at 90°C.

[0066] Comparative example 10 The preparation method of the fiber reinforced nylon composite of this example is the same as example 1 except that the mixing temperature in step S3 is controlled at 160°C.

[0067] Performance test (1) Tensile Tensile test was carried out according to GB / T1040.4.

[0068] (2) Bending Bending test was carried out according to GB / T1449-2005.

[0069] The fiber reinforced nylon composite materials prepared by the above examples and comparative examples were subjected to the above performance tests, and the test results are shown in Table 1.

[0070] Table 1

[0071]

[0072]

[0073] From Table 1, it can be seen that: According to Examples 1-9, and Comparative Examples 1, 2, the product performance is better when the mixing head injection pressure is 50-160 bar; the overall effect is best when it is between 90-120 bar; and the product performance is significantly deteriorated when it is higher than 160 bar or lower than 50 bar.

[0074] According to Examples 10-16, and Comparative Examples 3, 4, the product performance is better when the mold pressure holding pressure is 1200T-2400T; the product performance is better when it is between 1200T-2000T; and the product performance is significantly deteriorated when it is higher than 2400T or lower than 1200T.

[0075] According to Examples 17-21, and Comparative Examples 5, 6, the product performance is better when the mold pressure holding time is 3-8 minutes; the product performance is better when it is between 3-6 minutes; and the product performance is significantly deteriorated when it is higher than 8 minutes or lower than 3 minutes.

[0076] According to Examples 22-25, and Comparative Examples 7, 8, the product performance is better when the mold cavity temperature is 140-180℃; the product performance is better when it is between 150℃-170℃; and the product performance is significantly deteriorated when it is higher than 180℃ or lower than 140℃.

[0077] According to Examples 26-31, and Comparative Examples 9, 10, the product performance is better when the mixing temperature is 100-150; the product performance is best when it is between 105℃-125℃; and the product performance is significantly deteriorated when it is higher than 150℃ or lower than 100℃.

[0078] The above examples are only used to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the essential and scope of the technical solutions of the present application.

Claims

1. A method for producing a fiber-reinforced nylon composite material, characterized by, The preparation method comprises the following steps: S1. Dividing caprolactam into component A and component B, and heating and melting, dehydrating caprolactam; S2. Mixing the component A with a catalyst to obtain component A1, mixing the component B with an activator to obtain component B1, and dehydrating component A1 and component B1; S3. After mixing the component A1 and the component B1, high-pressure injection into the mold cavity of the preset fiber reinforced body, pressure curing forming, the pressure of the high-pressure injection is 50-160 bar, the pressure of the pressure curing is 1200T-2400T, the time is 3-8 minutes, and the temperature of the mold cavity is 140-180℃.

2. The method for preparing the fiber-reinforced nylon composite material according to claim 1, characterized in that, In the S1, the catalyst comprises at least one of metallic sodium, sodium hydroxide, potassium hydroxide and sodium methoxide.

3. The method for producing a fiber-reinforced nylon composite material according to claim 1 or 2, characterized by, In the S1, the activator comprises at least one of toluene diisocyanate, diphenyl methane diisocyanate and polymethylene polyisocyanate.

4. The method for preparing the fiber-reinforced nylon composite material according to claim 1, characterized in that, In the S1, the specific method of the dehydration is vacuum dehydration, the vacuum degree is ≤-0.098 Mpa, and the time of the vacuum dehydration is 30-45 min.

5. The method for preparing the fiber-reinforced nylon composite material according to claim 1, characterized in that, In the S2, the specific method of the dehydration is vacuum dehydration, the vacuum degree is ≤-0.098 Mpa, and the time of the vacuum dehydration is 40-60 min.

6. The method for preparing the fiber-reinforced nylon composite material according to claim 1, characterized in that, In the S3, the pressure of the high-pressure injection is 50-160 bar.

7. The method for preparing the fiber-reinforced nylon composite material according to claim 1, characterized in that, In the S3, the pressure of the pressure curing is 1200T-2000T, and the time is 3-6 minutes.

8. The method for preparing the fiber-reinforced nylon composite material according to claim 1, characterized in that, In the S3, the temperature of the mold cavity is 150-170℃.

9. The method for preparing the fiber-reinforced nylon composite material according to claim 1, characterized in that, In the S3, the temperature of the mixing of the component A1 and the component B1 is 95-125℃.

10. A fiber reinforced nylon composite material prepared by the preparation method in any one of claims 1-9.

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