Nylon 6 slice and production process thereof

Abstract

The invention provides a nylon 6 slice and a production process thereof, and belongs to the technical field of nylon 6 materials, and the nylon 6 slice comprises the following components in parts by weight: 72-75 parts of nylon 6, 3-5 parts of carbon nanotubes, 10-15 parts of brominated polystyrene powder, 6-8 parts of vanadium-doped mesoporous silica and 0.5-1.1 parts of an antioxidant. Vanadium-doped mesoporous silicon oxide and carbon nanotubes cooperate to form a three-dimensional network structure penetrating through a nylon 6 matrix, brominated polystyrene is fixed through chemical bonds (coordination bonds) and physical effects (adsorption and mechanical interlocking), and stable coexistence of multiple components is achieved; vanadium-doped mesoporous silicon oxide and carbon nanotubes synergistically enhance interface bonding, a high-modulus interface layer is formed through coordinate bonds and mechanical interlocking, loads are effectively transmitted, crack propagation is delayed, and then the mechanical property of the nylon 6 slice is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and particularly relates to a nylon 6 chip and its production process. Background Art

[0002] Polyamide, also known as nylon, has a wide range of applications. There are dozens of polyamide varieties, among which polyamide 6, polyamide 66, and polyamide 610 have the most extensive applications and the largest production.

[0003] In the prior art, in order to improve the flame retardancy of nylon 6 chips, the flame retardant brominated polystyrene is added. Although brominated polystyrene has good flame retardancy, the compatibility between brominated polystyrene flame retardant and nylon 6 is not ideal. During the processing, the brominated polystyrene flame retardant is difficult to be evenly dispersed in the nylon 6 matrix and is prone to agglomeration. When subjected to external forces, stress concentration is likely to occur at the interface, resulting in cracks or even fractures in the nylon 6 chips, thereby reducing the mechanical properties of the nylon 6 chips such as tensile strength and flexural strength. Summary of the Invention

[0004] To solve the problems in the background art, the present invention provides a nylon 6 chip and its production process, which can effectively improve the mechanical properties (tensile strength and flexural strength) of the obtained nylon 6 chips.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In the first aspect, a nylon 6 chip, by weight, comprises the following components: 72 - 75 parts of nylon 6, 3 - 5 parts of carbon nanotubes, 10 - 15 parts of brominated polystyrene powder, 6 - 8 parts of vanadium-doped mesoporous silica, and 0.5 - 1.1 parts of antioxidant.

[0007] Further, the preparation method of the vanadium-doped mesoporous silica is as follows:

[0008] A1. Add 0.1 mol of the cationic surfactant cetyltrimethylammonium bromide to an aqueous solution of dilute sulfuric acid, heat, stir and dissolve to obtain a mixed solution;

[0009] A2. Gradually add 0.5 mol of tetraethyl orthosilicate liquid to the mixed solution obtained in A1, then add 0.1 mol of ammonium metavanadate, and continue heating and stirring after dropping to obtain a colloid;

[0010] A3. Place the colloid obtained in A2 in a closed high-pressure reaction kettle, react at 100 - 120 °C for 4 h to obtain a reactant, take out the reactant after aging in an incubator to obtain a mixture, and obtain vanadium-doped mesoporous silica after filtration, washing, drying, and calcination of the mixture.

[0011] Further, in A1, the pH value of the dilute sulfuric acid aqueous solution is 1-2, the heating temperature is 60-65°C, and the stirring time is 5-5.5 h.

[0012] Further, in A2, the heating temperature is 60-65°C, and the stirring time is 4-5 h.

[0013] Further, in A3, the temperature of the incubator is 78-80°C, and the aging time is 24-48 h.

[0014] Further, in A3, the calcination temperature is 450-500°C, and the calcination time is 6-8 h.

[0015] In a second aspect, a production process of nylon 6 chips includes the following steps:

[0016] S1. Add nylon 6, carbon nanotubes, brominated polystyrene powder, and antioxidant into a high-speed mixer for mixing to obtain a mixed material.

[0017] S2. Add vanadium-doped mesoporous silica to the mixed material in S1 and continue to mix in the high-speed mixer to obtain a premixed material.

[0018] S3. Add the premixed material in S2 into a twin-screw extruder, and after extrusion, it is cooled by water and pelletized to obtain nylon 6 chips.

[0019] Further, the temperatures of the twin-screw extruder from the feeding section to the head are 220°C, 240°C, 250°C, 245°C, and 230°C in sequence.

[0020] This application has the following beneficial effects:

[0021] After the carbon nanotubes are added in the present invention, due to the high specific surface area and high surface energy of the carbon nanotubes, the carbon nanotubes preferentially aggregate at the interface, breaking the original weak interface bonding state between nylon 6 and brominated polystyrene, and forming a "starting point for interface reconstruction".

[0022] After the vanadium-doped mesoporous silica is added in the present invention, the doping of vanadium increases the Lewis acid sites on the surface of silica, forms a coordination bond with the polar group (-NHCO-) of nylon 6, and at the same time adsorbs brominated polystyrene through hydrophobic interaction. The hydrophobic surface of the mesoporous silica wraps the brominated polystyrene particles through physical adsorption.

[0023] Vanadium-doped mesoporous silica and carbon nanotubes cooperate to form a three-dimensional network structure that penetrates the nylon 6 matrix, and brominated polystyrene is fixed through chemical bonds (coordination bonds) and physical interactions (adsorption, mechanical interlocking) to achieve the stable coexistence of multiple components; vanadium-doped mesoporous silica and carbon nanotubes jointly enhance the interfacial bonding, form a high-modulus interfacial layer through coordination bonds and mechanical interlocking, effectively transfer the load and delay crack propagation, thereby improving the mechanical properties of nylon 6 chips. Description of the Drawings

[0024] Figure 1 、Comparison trend chart of the tensile strength test data of the nylon 6 chips prepared in Examples 1-3 and Comparative Examples 1-3 in the test examples of the present invention;

[0025] Figure 2 、Comparison trend chart of the flexural strength test data of the nylon 6 chips prepared in Examples 1-3 and Comparative Examples 1-3 in the test examples of the present invention. Detailed Description of the Invention

[0026] The following further describes the present application in detail with reference to the examples.

[0027] The raw materials of the examples and comparative examples of the present application are all ordinary commercially available except as otherwise specified.

[0028] Example 1: (1) The preparation method of vanadium-doped mesoporous silica is as follows:

[0029] A1. Add 0.1 mol of cationic surfactant cetyltrimethylammonium bromide to dilute sulfuric acid aqueous solution, heat, stir and dissolve to obtain a mixed solution; the pH value of the dilute sulfuric acid aqueous solution is 1.6, the heating temperature is 60 °C, the stirring speed is 220 r / min, and the stirring time is 5 h.

[0030] A2. Gradually add 0.5 mol of tetraethyl orthosilicate liquid to the mixed solution described in A1, and then add 0.1 mol of ammonium metavanadate. After the addition is completed, continue to heat to a temperature of 60 °C and continue to stir at a stirring speed of 220 r / min for 4 h to obtain a colloid.

[0031] A3. Place the colloid obtained in A2 in a closed high-pressure reaction kettle, react at 100 °C for 4 h to obtain a reactant, take out the reactant after aging at a temperature of 78 °C in an incubator for 24 h to obtain a mixture, and the mixture is filtered, washed, dried and calcined to obtain vanadium-doped mesoporous silica. The calcination temperature is 450 °C and the calcination time is 6 h.

[0032] Among them, the cationic surfactant cetyltrimethylammonium bromide was purchased from Shanghai Shengwei Chemical Raw Materials Co., Ltd. Tetraethyl orthosilicate liquid was purchased from Guangzhou Shuangtao Fine Chemical Co., Ltd. Ammonium metavanadate, analytical pure, was purchased from Langfang Pengcai Fine Chemical Co., Ltd.

[0033] (2) A production process of nylon 6 chips includes the following steps:

[0034] S1. Add 72 parts of nylon 6, 3 parts of carbon nanotubes, 10 parts of brominated polystyrene powder, and 0.5 part of antioxidant into a high-speed mixer for mixing. The mixing time is 3 min, and the rotation speed of the high-speed mixer is 900 rpm to obtain a mixed material.

[0035] S2. Add 6 parts of vanadium-doped mesoporous silica to the mixed material in S1 and continue to mix in the high-speed mixer for 2 min to obtain a premixed material.

[0036] S3. Add the premixed material in S2 into a twin-screw extruder. The screw rotation speed is 230 r / min, and co-mix and melt-extrude. After extrusion, it is cooled by water and pelletized to obtain nylon 6 chips. The twin-screw extruder includes a feeding section, a melting section, a kneading section, a homogenizing section, and a head section from the feeding section to the head. The temperatures of the feeding section, the melting section, the kneading section, the homogenizing section, and the head section are 220 °C, 240 °C, 250 °C, 245 °C, and 230 °C respectively.

[0037] Among them, nylon 6 was from Henan Shenma Pulai Materials Co., Ltd. Carbon nanotubes were purchased from Hebei Wenchang Energy Saving Technology Co., Ltd. Brominated polystyrene powder with a CAS number of 88497-56-7 was purchased from Shandong Yinglang Chemical Co., Ltd. The antioxidant was antioxidant 1010 and was purchased from Dongguan Xingyuan Chemical Co., Ltd.

[0038] Example 2: (1) The preparation method of vanadium-doped mesoporous silica is as follows:

[0039] A1. Add 0.1 mol of the cationic surfactant cetyltrimethylammonium bromide into an aqueous solution of dilute sulfuric acid, heat, stir, and dissolve to obtain a mixed solution; the pH value of the aqueous solution of dilute sulfuric acid is 1.6, the heating temperature is 60 °C, and the stirring time is 5 h.

[0040] A2. Dropwise add 0.5 mol of tetraethyl orthosilicate liquid into the mixed solution in A1, then add 0.1 mol of ammonium metavanadate. After the dropping is completed, continue to heat to a temperature of 60 °C and stir for 4 h to obtain a colloid.

[0041] A3. Place the colloid obtained in A2 in a closed high-pressure reactor, react at 100 °C for 4 h to obtain a reactant. Take out the reactant after aging at 78 °C for 24 h in an incubator to obtain a mixture. The mixture is filtered, washed, dried and calcined to obtain vanadium-doped mesoporous silica. The calcination temperature is 450 °C and the calcination time is 6 h.

[0042] Among them, the cationic surfactant cetyltrimethylammonium bromide was purchased from Shanghai Shengwei Chemical Raw Materials Co., Ltd. Tetraethyl orthosilicate liquid was purchased from Guangzhou Shuangtao Fine Chemical Co., Ltd. Ammonium metavanadate, analytical pure, was purchased from Langfang Pengcai Fine Chemical Co., Ltd.

[0043] (2) A production process of nylon 6 chips, comprising the following steps:

[0044] S1. Add 75 parts of nylon 6, 5 parts of carbon nanotubes, 15 parts of brominated polystyrene powder and 1.1 parts of antioxidant to a high-speed mixer for mixing. The mixing time is 3 min and the rotation speed of the high-speed mixer is 900 rpm to obtain a mixed material.

[0045] S2. Add 8 parts of vanadium-doped mesoporous silica to the mixed material in S1 and continue to mix in the high-speed mixer for 2 min to obtain a premixed material.

[0046] S3. Add the premixed material in S2 to a twin-screw extruder. The screw rotation speed is 230 r / min, and the materials are melt-extruded by co-mixing. After extrusion, it is cooled by water and pelletized to obtain nylon 6 chips. The twin-screw extruder is composed of a feeding section, a melting section, a kneading section, a homogenizing section and a head section from the feeding section to the head. The temperatures of the feeding section, the melting section, the kneading section, the homogenizing section and the head section are 220 °C, 240 °C, 250 °C, 245 °C and 230 °C respectively.

[0047] Example 3: (1) The preparation method of vanadium-doped mesoporous silica is as follows:

[0048] A1. Add 0.1 mol of the cationic surfactant cetyltrimethylammonium bromide to an aqueous solution of dilute sulfuric acid, heat, stir and dissolve to obtain a mixed solution; the pH value of the aqueous solution of dilute sulfuric acid is 1.6, the heating temperature is 60 °C, and the stirring time is 5 h.

[0049] A2. Dropwise add 0.5 mol of tetraethyl orthosilicate liquid to the mixed solution in A1, then add 0.1 mol of ammonium metavanadate. After the dropping is completed, continue to heat to 60 °C and stir for 4 h to obtain a colloid.

[0050] A3. Place the colloid obtained in A2 in a closed high-pressure reactor, react at 100 °C for 4 h to obtain a reactant. Take out the reactant after aging at 78 °C for 24 h in an incubator to obtain a mixture. The mixture is filtered, washed, dried, and calcined to obtain vanadium-doped mesoporous silica. The calcination temperature is 450 °C and the calcination time is 6 h.

[0051] Among them, the cationic surfactant cetyltrimethylammonium bromide was purchased from Shanghai Shengwei Chemical Raw Materials Co., Ltd. Tetraethyl orthosilicate liquid was purchased from Guangzhou Shuangtao Fine Chemical Co., Ltd. Ammonium metavanadate, analytical pure, was purchased from Langfang Pengcai Fine Chemical Co., Ltd.

[0052] (2) A production process of nylon 6 chips, comprising the following steps:

[0053] S1. Add 73 parts of nylon 6, 4 parts of carbon nanotubes, 12 parts of brominated polystyrene powder, and 0.8 part of antioxidant to a high-speed mixer and mix for 3 min at a rotation speed of 900 rpm of the high-speed mixer to obtain a mixed material.

[0054] S2. Add 7 parts of vanadium-doped mesoporous silica to the mixed material in S1 and continue to mix in the high-speed mixer for 2 min to obtain a premixed material.

[0055] S3. Add the premixed material in S2 to a twin-screw extruder, with a screw rotation speed of 230 r / min, and carry out co-mixing and melt extrusion. After extrusion, it is cooled by water and pelletized to obtain nylon 6 chips. The twin-screw extruder consists of a feeding section, a melting section, a kneading section, a homogenizing section, and a head section from the feeding section to the head. The temperatures of the feeding section, the melting section, the kneading section, the homogenizing section, and the head section are 220 °C, 240 °C, 250 °C, 245 °C, and 230 °C, respectively.

[0056] Comparative Example 1: The difference between this comparative example and Example 1 is that carbon nanotubes and vanadium-doped mesoporous silica are deleted.

[0057] Specifically, a production process of nylon 6 chips, comprising the following steps:

[0058] S1. Add 72 parts of nylon 6, 10 parts of brominated polystyrene powder, and 0.5 part of antioxidant to a high-speed mixer and mix for 3 min at a rotation speed of 900 rpm of the high-speed mixer to obtain a mixed material.

[0059] S2. Add the mixture in S1 into a twin-screw extruder with a screw speed of 230 r / min, and conduct co-blending, melting and extrusion. After extrusion, it goes through water cooling and pelletizing to obtain nylon 6 chips. The twin-screw extruder includes a feeding section, a melting section, a mixing section, a homogenizing section and a head section from the feeding section to the head. The temperatures of the feeding section, the melting section, the mixing section, the homogenizing section and the head section are 220 °C, 240 °C, 250 °C, 245 °C and 230 °C respectively.

[0060] Comparative Example 2: The difference between this comparative example and Example 1 is that the vanadium-doped mesoporous silica is deleted.

[0061] Specifically, (2) A production process of nylon 6 chips includes the following steps:

[0062] S1. Add 72 parts of nylon 6, 3 parts of carbon nanotubes, 10 parts of brominated polystyrene powder and 0.5 part of antioxidant into a high-speed mixer for mixing. The mixing time is 3 min and the rotation speed of the high-speed mixer is 900 rpm to obtain a mixture.

[0063] S2. Add 6 parts of vanadium-doped mesoporous silica to the mixture in S1 and continue to mix in the high-speed mixer for 2 min to obtain a premix.

[0064] S3. Add the premix in S2 into a twin-screw extruder with a screw speed of 230 r / min, and conduct co-blending, melting and extrusion. After extrusion, it goes through water cooling and pelletizing to obtain nylon 6 chips. The twin-screw extruder includes a feeding section, a melting section, a mixing section, a homogenizing section and a head section from the feeding section to the head. The temperatures of the feeding section, the melting section, the mixing section, the homogenizing section and the head section are 220 °C, 240 °C, 250 °C, 245 °C and 230 °C respectively.

[0065] Comparative Example 3: The difference between this comparative example and Example 1 is that the carbon nanotubes are deleted.

[0066] Specifically, (2) A production process of nylon 6 chips includes the following steps:

[0067] S1. Add 72 parts of nylon 6, 10 parts of brominated polystyrene powder and 0.5 part of antioxidant into a high-speed mixer for mixing. The mixing time is 3 min and the rotation speed of the high-speed mixer is 900 rpm to obtain a mixture.

[0068] S2. Add 6 parts of vanadium-doped mesoporous silica to the mixture in S1 and continue to mix in the high-speed mixer for 2 min to obtain a premix.

[0069] S3. Add the premix in S2 to a twin-screw extruder with a screw speed of 230 r / min, and conduct co-blending and melt extrusion. After extrusion, it is cooled by water and pelletized to obtain nylon 6 chips. The twin-screw extruder consists of a feeding section, a melting section, a kneading section, a homogenizing section, and a die head section from the feeding section to the die head. The temperatures of the feeding section, melting section, kneading section, homogenizing section, and die head section are 220 °C, 240 °C, 250 °C, 245 °C, and 230 °C respectively.

[0070] Test example: Test objects: Nylon 6 chips prepared in Examples 1 - 3 and Comparative Examples 1 - 3.

[0071] Test items: Tensile strength and flexural strength.

[0072] Test method: Place the nylon 6 chips prepared in Examples 1 - 3 and Comparative Examples 1 - 3 in a forced-air drying oven and dry them at 110 °C for 4 h. Then, prepare test specimens using an injection molding machine and conduct performance tests. The reference for the tensile strength test is GB / T 1040.2 - 2006, and the reference for the flexural strength test is GB / T 9341 - 2008.

[0073] Test results: See Table 1.

[0074] Table 1

[0075] Tensile strength / MPa Flexural strength / MPa Example 1 78.6 95.3 Example 2 78.4 95.6 Example 3 79.2 95.4 Comparative Example 1 73.2 91.4 Comparative Example 2 72.1 90.2 Comparative Example 3 74.5 93.6

[0076] Result analysis: Analyze Examples 1 - 3 and combine with the data in Table 1 and Figure 1 - Figure 2 It can be seen that the tensile strength test data of the nylon 6 chips prepared in the present invention (Examples 1 - 3) reach above 78.4 MPa, and the flexural strength test data reach above 95.3 MPa, indicating that the mechanical properties (tensile strength and flexural strength) of the nylon 6 chips prepared in the present invention are excellent.

[0077] Analyze Example 1 and Comparative Examples 1 - 3 and combine with the data in Table 1 and Figure 1 - Figure 2 . By comparing Comparative Example 1 and Comparative Example 2, it can be known that compared with Comparative Example 1, 3 parts of carbon nanotubes were added alone in Comparative Example 2. As a result, the tensile strength and flexural strength of the nylon 6 chips prepared in Comparative Example 2 are less than those of the nylon 6 chips prepared in Comparative Example 1, indicating that adding carbon nanotubes alone will cause the mechanical properties (tensile strength and flexural strength) of the prepared nylon 6 chips to decrease instead of increase.

[0078] This is because, on the one hand, the high specific surface area and high surface energy of carbon nanotubes make them easily enriched at the interface between nylon 6 and brominated polystyrene. When there is a weak interfacial bond between nylon 6 and brominated polystyrene, the preferential aggregation of carbon nanotubes will form a physical barrier, weakening the original weak interfacial bonding force between the two, resulting in a further decrease in the mechanical properties (tensile strength and flexural strength) of nylon 6 slices; on the other hand, the carbon nanotubes enriched at the interface fail to form an effective interfacial bond, which will become a stress concentration point, inducing crack initiation and propagation, leading to a decrease in tensile strength and flexural strength.

[0079] In summary, in the single nylon 6 matrix of the prior art, when carbon nanotubes are uniformly dispersed, the mechanical properties can be improved through the strengthening effect; however, in the nylon 6 and brominated polystyrene blend system, the interfacial distribution state of the separately added carbon nanotubes significantly changes its action mechanism, resulting in differences in performance changes.

[0080] By comparing Comparative Example 1 and Comparative Example 3, it can be seen that compared with Comparative Example 1, 6 parts of vanadium-doped mesoporous silica were separately added in Comparative Example 3. As a result, the drawstring strength and flexural strength of the nylon 6 slices prepared in Comparative Example 3 are greater than those of the nylon 6 slices prepared in Comparative Example 1, indicating that separately adding vanadium-doped mesoporous silica can improve the mechanical properties (tensile strength and flexural strength) of the prepared nylon 6 slices.

[0081] This is because after the addition of vanadium-doped mesoporous silica, the doping of vanadium increases the Lewis acid sites on the surface of silica, forming coordination bonds with the polar groups (-NHCO-) of nylon 6. At the same time, brominated polystyrene is adsorbed through hydrophobic interaction, and the hydrophobic surface of mesoporous silica can also wrap brominated polystyrene particles through physical adsorption.

[0082] Combined with Comparative Example 1 for comparison, it can be seen that when carbon nanotubes and vanadium-doped mesoporous silica are added simultaneously, the two can produce a synergistic effect, synergistically improving the mechanical properties (tensile strength and flexural strength) of nylon 6 slices.

[0083] In addition, it should be noted that among the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0084] In addition, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention.

Claims

1. A nylon 6 chip, characterized in that, By weight, it includes the following components: 72 - 75 parts of nylon 6, 3 - 5 parts of carbon nanotubes, 10 - 15 parts of brominated polystyrene powder, 6 - 8 parts of vanadium-doped mesoporous silica, and 0.5 - 1.1 parts of antioxidant.

2. The nylon 6 chip according to claim 1, wherein The preparation method of the vanadium-doped mesoporous silica is as follows: A1. Add 0.1 mol of cationic surfactant cetyltrimethylammonium bromide into dilute sulfuric acid aqueous solution, heat, stir and dissolve to obtain a mixed solution; A2. Dropwise add 0.5 mol of tetraethyl orthosilicate liquid into the mixed solution obtained in A1, then add 0.1 mol of ammonium metavanadate, and continue heating and stirring after dropping to obtain a colloid; A3. Place the colloid obtained in A2 in a closed high-pressure reaction kettle, react at 100–120 °C for 4 h to obtain a reactant, take out the reactant after aging in an incubator, obtain a mixture, and obtain vanadium-doped mesoporous silica after suction filtration, washing, drying and calcination.

3. The nylon 6 chip according to claim 2, wherein In A1, the pH value of the dilute sulfuric acid aqueous solution is 1 - 2, the heating temperature is 60 - 65 °C, and the stirring time is 5 - 5.5 h.

4. The nylon 6 chip according to claim 2, wherein, In A2, the heating temperature is 60 - 65 °C, and the stirring time is 4 - 5 h.

5. The nylon 6 chip according to claim 2, characterized in that, In A3, the temperature of the incubator is 78 - 80 °C, and the aging time is 24 - 48 h.

6. The nylon 6 chip according to claim 2, wherein In A3, the calcination temperature is 450 - 500 °C, and the calcination time is 6 - 8 h.

7. A production process of nylon 6 chips as described in any one of claims 1-6, characterized in that, It includes the following steps: S1. Add nylon 6, carbon nanotubes, brominated polystyrene powder, and antioxidant into a high-speed mixer and mix to obtain a mixed material; S2. Add vanadium-doped mesoporous silica to the mixed material in S1 and continue to mix in the high-speed mixer to obtain a premixed material; S3. Add the premixed material in S2 into a twin-screw extruder, extrude, cool with water and pelletize to obtain nylon 6 chips.

8. The production process of nylon 6 chips according to claim 7, characterized in that, The temperatures of the twin-screw extruder from the feeding section to the head are 220 °C, 240 °C, 250 °C, 245 °C and 230 °C in sequence.

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