High-impact precipitation-resistant halogen-free flame-retardant modified nylon 12 material and preparation method thereof

Abstract

The invention discloses a high-impact precipitation-resistant halogen-free flame-retardant modified nylon 12 material and a preparation method thereof. The nylon 12 material is prepared from the following components in parts by weight: nylon 12 with specific end group content, in-situ grafting toughening agent master batch, in-situ fiber forming flame retardant master batch and 0 to 4 parts of processing aid. The preparation method of the in-situ grafted toughening agent master batch is adopted, the nylon 12 resin with specific end group content is matched, and after the in-situ reaction of the high-content polar monomer of the grafted toughening agent and the amino group at the end of the nylon 12 is complete, a considerable number of polar groups are still reserved to be chemically bonded with the amino group in an MCA compound system; the dispersion condition of the flame retardant in the nylon 12 resin is effectively improved; meanwhile, the acrylic acid modified polytetrafluoroethylene forms a microfibrillated network in situ in the mixing process of the continuous internal mixer, precipitation of a flame retardant can be inhibited, the material is endowed with an anti-dripping characteristic, and finally the halogen-free flame-retardant modified nylon 12 material with high impact and precipitation resistance characteristics is obtained.

Description

Technical Field

[0001] The present invention relates to a reinforced nylon 12 material, and particularly to a high-impact, halogen-free flame-retardant and precipitation-resistant modified nylon 12 material and a preparation method thereof, belonging to the technical field of polymer materials. Background Art

[0002] Nylon 12 is a polyamide variety with 12 methylene groups between adjacent amide groups. Its long methylene chain and polar amide groups endow it with the dual characteristics of polyolefins and polyamides. While having excellent mechanical strength, wear resistance, chemical solvent resistance and other properties, it overcomes the disadvantages of short-chain nylon such as size instability caused by high water absorption and poor low-temperature toughness, and has important applications in the fields of automobiles, electronic appliances, aerospace, oil pipelines, etc. However, in terms of flame-retardant applications, due to the low density of amide bonds in nylon 12 and poor char-forming ability, unmodified nylon 12 has poor flame retardancy and is prone to cause fires in some scenarios.

[0003] The flame-retardant modification of nylon 12 is usually divided into halogen-containing flame-retardant modification and halogen-free flame-retardant modification. Although halogen-based flame retardants have good thermal stability and physical and mechanical properties, the thick smoke, toxicity, and corrosive gases generated during flame retardancy will cause serious secondary disasters and have been banned by more and more countries. Halogen-free flame retardants mainly based on melamine salts have received more and more attention. For example, the nitrogen-based halogen-free flame retardant MCA has the advantages of high nitrogen content, low toxicity, low smoke and high efficiency. It decomposes a large amount of inert gas at high temperature. On the one hand, these inert gases reduce the surface temperature of the polymer material and isolate air through "sublimation heat absorption", and on the other hand, they will cause the carbonized layer of the material to expand and foam during combustion, thereby isolating oxygen and preventing combustion. However, halogen-free flame retardants have processing difficulties, poor dispersion in the substrate, and poor thermal stability, which easily affect the impact strength and flame-retardant stability of the material.

[0004] Chinese Patent CN103087312B discloses a P-N type flame-retardant masterbatch, a flame-retardant nylon engineering plastic and a preparation method thereof. By synthesizing a highly compatible flame-retardant masterbatch through an interfacial chemical reaction between the flame retardant and nylon, the flame-retardant efficiency is improved and the amount of the flame retardant is reduced. However, there are problems such as complex processes and small sample amounts, which are difficult to meet the needs of industrial promotion; Chinese Patent CN103627168A discloses a special halogen-free flame-retardant masterbatch for nylon and a preparation method thereof, and a high-concentration flame-retardant masterbatch is prepared by a direct-cut underwater pelletizing process to solve the problems of difficult feeding of the flame retardant and uneven feeding, but it cannot improve the impact performance affected by halogen-free flame retardancy; Chinese Patent CN112608592A discloses a highly dispersible and high-concentration nylon-based halogen-free flame-retardant masterbatch and a preparation method thereof. Through the screening of nylon resin, lubricating dispersant and yellowing-resistant agent, high filling of the nylon carrier is achieved, and it also cannot solve the problem of low impact strength after flame-retardant modification. Summary of the Invention

[0005] To overcome the deficiencies of the prior art, the present invention provides a high-impact halogen-free flame-retardant modified nylon 12 material and its preparation method, which can effectively improve the compatibility between nylon 12 resin and the flame retardant, improve the flame-retardant efficiency, reduce the precipitation of the flame retardant, and at the same time enhance the impact strength of the product on the premise of ensuring V0-level flame retardancy.

[0006] To achieve the above technical effects, the present invention adopts the following technical solutions:

[0007] A high-impact halogen-free flame-retardant modified nylon 12 material, by weight, comprises the following parts:

[0008] Nylon 12 with a specific end-group content, 35 - 85 parts, preferably 50 - 70 parts;

[0009] In-situ graft toughening agent masterbatch, 10 - 40 parts, preferably 20 - 30 parts;

[0010] In-situ fibrillating flame-retardant masterbatch, 10 - 40 parts, preferably 20 - 30 parts;

[0011] Processing aids, 0 - 4 parts, preferably 1 - 2 parts;

[0012] Among them, the nylon 12 with a specific end-group content has an amino end-group content of 10 - 50 mmol / kg, preferably 20 - 30 mmol / kg; the ratio of amino end-group to carboxyl end-group is 1:1 - 1:4, preferably 1:2 - 1:3; the number-average molecular weight ranges from 40,000 to 50,000, preferably 45,000 - 48,000; the polydispersity coefficient is 1.2 - 2.0, preferably 1.5 - 1.8.

[0013] The in-situ graft toughening agent masterbatch of the present invention, by weight, comprises the following parts:

[0014] Nylon 12 with a specific end-group content, 40 - 80 parts, preferably 60 - 70 parts;

[0015] Toughening agent, 10 - 40 parts, preferably 20 - 30 parts;

[0016] Graft monomer, 1 - 4 parts, preferably 2 - 3 parts;

[0017] Initiator, 0.1 - 0.5 parts, preferably 0.2 - 0.3 parts;

[0018] Processing aids, 0 - 3 parts, preferably 1 - 2 parts;

[0019] Among them, the amino group content of the specific end group-containing nylon 12 is 10 - 50 mmol / kg, preferably 20 - 30 mmol / kg; the ratio of amino group to carboxyl group is 1:1 - 1:4, preferably 1:2 - 1:3; the number average molecular weight ranges from 40,000 to 50,000, preferably 45,000 - 48,000; the polydispersity coefficient is 1.2 - 2.0, preferably 1.5 - 1.8.

[0020] Furthermore, the toughening agent is at least one of ethylene-octene copolymer (POE), ethylene-propylene copolymer (EPR), ethylene-propylene-non-conjugated diene copolymer (EPDM), styrene-butadiene copolymer (SBS), styrene-ethylene-butene-styrene block copolymer (SEBS), ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methacrylic acid copolymer (EMA), ethylene-butyl acrylate (EBA), etc., preferably one or several of EMA, EAA, and EEA.

[0021] Furthermore, the graft monomer is one or several of maleic anhydride (MAH) graft and its derivatives, acrylate (AA) and its derivatives, methacrylic acid, unsaturated fatty acid, methylene succinic acid, glycidyl methacrylate (GMA), styrene (St), divinylbenzene (DVB), bismaleimide (BMI), triallyl isocyanurate (TAIC), etc., preferably MAH and St are compounded in a weight ratio of 1:1.

[0022] Furthermore, the initiator is benzoyl peroxide (BPO), dicumyl peroxide (DCP), 2,5-dimethyl-2,5-bis(tert-butylperoxy)ethane (DHBP), 2,3-dimethyl-2,3-diphenylbutane (DMDPB), etc., preferably DCP and BPO are compounded in a weight ratio of 1:1.

[0023] Furthermore, the processing aid contains a lubricant and an antioxidant. Among them, the lubricant is one or several of polyethylene waxes, low molecular esters, metal soaps, stearic acid composite esters, amide waxes, montan waxes, and low-viscosity bisphenol A epoxy resins. Preferably, stearic acid composite esters and montan waxes are compounded in a weight ratio of 1:1; the antioxidant is one or several of copper salts, phosphates, hindered phenols, phosphites, thioesters, and high molecular antioxidants. Preferably, hindered phenols and phosphite antioxidants are compounded, and more preferably, antioxidant 1098 and antioxidant 168 are compounded in a weight ratio of 1:1.

[0024] The preparation method of the in-situ graft toughening agent masterbatch described in the present invention comprises the following steps:

[0025] (1) Dissolve the grafting monomer and initiator in acetone to form a solution;

[0026] (2) Stir through a high-speed mixer to raise the temperature of the toughening agent to between 80 - 100 °C, add the acetone solution containing the grafting monomer and initiator, as well as the processing aids, and control the temperature below 100 °C during the stirring process to promote the solution mixed with the grafting monomer and initiator to penetrate into the toughening agent;

[0027] (3) Feed the product of step (2) and 30 - 35 parts of nylon 12 with a specific end group content into a twin-screw extruder through the main feed port for pelletizing, and add the remaining nylon 12 with a specific end group content through the side feed port.

[0028] In step (1) of the present invention, the amount of acetone used is 3 - 4 times the sum of the volumes of the grafting monomer and initiator.

[0029] Furthermore, the length-diameter ratio of the extruder screw is 36:1 - 50:1, preferably 44:1 - 48:1; the extrusion temperature is 210 - 300 °C, preferably 250 - 270 °C; the screw speed is 200 - 800 rpm, preferably 500 - 700 rpm.

[0030] The in-situ fibrillating flame retardant masterbatch of the present invention, by weight, comprises the following components:

[0031] In-situ grafting toughening agent masterbatch: 20 - 50 parts, preferably 30 - 40 parts;

[0032] Main flame retardant: 40 - 60 parts, preferably 40 - 50 parts;

[0033] Synergistic flame retardant: 5 - 20 parts, preferably 10 - 15 parts;

[0034] In-situ fibrillating substance: 5 - 20 parts, preferably 10 - 15 parts.

[0035] Furthermore, the in-situ grafting toughening agent masterbatch is obtained by the aforementioned method.

[0036] Furthermore, the main flame retardant is one or more of melamine cyanurate (MCA), melamine polyphosphate (MPP), and preferably MCA with a particle size between 1.1 - 1.4 μm is used as the main flame retardant.

[0037] Furthermore, the synergistic flame retardant is one or more of ammonium polyphosphate (APP), aluminum diethylphosphinate (ADP), aluminum hydroxide, magnesium hydroxide, pentaerythritol, zinc borate, expanded graphite, chlorinated paraffin, and preferably APP is used as the synergistic flame retardant.

[0038] Furthermore, the in-situ fibrillating substance is one or more of polytetrafluoroethylene (PTFE), polyamide (PA), and polyethylene terephthalate (PET), preferably PTFE, and more preferably acrylic acid-modified PTFE.

[0039] The preparation method of the in-situ fibrillating flame retardant masterbatch of the present invention comprises the following steps:

[0040] (1) Weigh the in-situ grafting toughening agent masterbatch and the in-situ fibrillating substance according to the ratio, mix them evenly by a high-speed mixer, and then transfer them to the kneading section of a continuous kneader for kneading for 3-5 minutes. Then add the main flame retardant and the synergistic flame retardant and knead for 6-10 minutes to obtain a dough-like kneaded material;

[0041] (2) Feed the dough-like kneaded material into the twin-screw section of the continuous kneader by forced feeding, and granulate it after melt extrusion to obtain the in-situ fibrillating flame retardant masterbatch.

[0042] Furthermore, in the continuous kneader, the kneader speed is 50-100 rpm, the kneader temperature is 200-280 °C, preferably 210-220 °C; the screw length-diameter ratio is 6:1-12:1, preferably 8:1; the extrusion temperature is 200-280 °C, preferably 210-220 °C; the screw speed is 100-400 rpm, preferably 200-300 rpm.

[0043] The preparation method of the high-impact halogen-free flame retardant modified nylon 12 material of the present invention comprises the following steps: Mix the nylon 12 with a specific end group content, the in-situ grafting toughening agent masterbatch, and the processing aid evenly, add them through the main feeding port, and add the in-situ fibrillating flame retardant masterbatch through the side feeding port, and granulate them using a twin-screw extruder.

[0044] Furthermore, in the preparation method of the high-impact halogen-free flame retardant modified nylon 12 material, the screw length-diameter ratio of the twin-screw extruder is 36:1-50:1, preferably 38:1-42:1; the extrusion temperature is 210-300 °C, preferably 240-250 °C; the screw speed is 200-800 rpm, preferably 300-400 rpm.

[0045] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0046] (1) The present invention adopts the preparation method of the in-situ grafting toughening agent masterbatch, and cooperates with the nylon 12 resin with a specific end group content and the ratio of terminal amino group to terminal carboxyl group. During the process of grafting polar groups by the toughening agent, an in-situ reaction between the nylon 12 resin and the polar groups can be realized, which can significantly enhance the chemical bonding effect between the nylon 12 and the polar groups of the grafting toughening agent;

[0047] (2) The toughener is premixed at high speed with an acetone solution dissolved with graft monomers and initiators. With the design of a twin-screw extruder with a high length-diameter ratio and process parameters, the grafting efficiency of the toughener monomers can be further improved, as well as the reaction between the nylon 12 resin and the polar groups of the toughener. Meanwhile, the dispersion effect of the graft toughener in the nylon 12 resin can be improved;

[0048] (3) After the graft toughener with a high content of polar monomers reacts with the terminal amino groups of the nylon 12 resin with a specific terminal group content, a considerable number of polar groups still remain to form chemical bonding with the amino groups in the MCA compounding system, thereby effectively improving the compatibility of the graft toughener with the MCA compounding system and improving the dispersion of the flame retardant in the nylon 12 resin;

[0049] (4) Through the high-temperature and high-shear mixing of a continuous internal mixer, the in-situ fibrillating substance is fully microfibrillated in the resin matrix. Due to the good compatibility between it and the non-polar molecular backbone of the toughener, the fibrillar network structure can effectively limit the precipitation of the flame retardant and endow the material with a drip-proof property, further improving the flame retardancy efficiency.

[0050] (5) The stronger chemical bonding between the in-situ graft toughener and the nylon 12 with a specific terminal group content and the MCA flame retardant system greatly improves the impact strength of the halogen-free flame retardant system on the premise of achieving stable V0-level flame retardancy; while the in-situ microfibrillated network of acrylic acid-modified polytetrafluoroethylene with good compatibility with the graft toughener restricts the precipitation of the flame retardant, further improving the flame retardancy efficiency of the material. Finally, a halogen-free flame retardant modified nylon 12 material with high impact and anti-precipitation properties is prepared. Specific Embodiments

[0051] The following are specific examples of the present invention, which further describe the technical solutions of the present invention, but the content of the present invention includes but is not limited to these examples.

[0052] The information of the raw materials used in the experimental examples and comparative examples is as follows.

[0053] Nylon 12-A, with a molecular weight of 45980, a polydispersity coefficient of 1.8067, a terminal amino group content of 25 mmol / kg, and a ratio of terminal amino groups to terminal carboxyl groups of 1:2, self-made;

[0054] Nylon 12-B, with a molecular weight of 43212, a polydispersity coefficient of 1.8597, a terminal amino group content of 30 mmol / kg, and a ratio of terminal amino groups to terminal carboxyl groups of 1:1, self-made;

[0055] Nylon 12-C, with a molecular weight of 47006, a polydispersity coefficient of 1.7871, a terminal amino group content of 60 mmol / kg, and a ratio of terminal amino groups to terminal carboxyl groups of 2:1, self-made;

[0056] Toughening agent A, ethylene-methyl acrylate copolymer (EMA), grade AC1125, methyl acrylate content 25 wt%, Dow Chemical;

[0057] Toughening agent B, POE, grade ENGAGE 8480, Dow Chemical;

[0058] Grafting monomer A, maleic anhydride (MAH), Shanghai Aladdin;

[0059] Grafting monomer B, styrene (St), Shanghai Aladdin;

[0060] Initiator A, benzoyl peroxide (BPO), Shanghai Aladdin;

[0061] Initiator B, dicumyl peroxide (DCP), Shanghai Aladdin;

[0062] Grafted toughening agent A, ethylene-methyl acrylate copolymer grafted maleic anhydride (GMA-g-MAH), grade A560, DuPont Chemical;

[0063] Grafted toughening agent B, ethylene-octene copolymer grafted maleic anhydride (POE-g-MAH), grade MH5040, Mitsui Chemicals;

[0064] Flame retardant A, melamine cyanurate (MCA), grade Melapur MC25, BASF;

[0065] Flame retardant B, ammonium polyphosphate (APP), grade PHOS-CHEK P / 30, Monsanto;

[0066] In-situ fibrillation substance, acrylic acid modified polytetrafluoroethylene, grade METABLEN A-3000, Mitsubishi Chemical;

[0067] Lubricant, metal soap lubricant, calcium stearate, Clariant;

[0068] Lubricant, stearic acid compound ester, pentaerythritol stearate, Emery Oleochemicals;

[0069] Antioxidant, hindered phenol antioxidant, 1098, BASF;

[0070] Antioxidant, hindered phenol antioxidant, 1010, BASF;

[0071] Antioxidant, phosphite antioxidant, grade 168, BASF;

[0072] The present invention will be further illustrated by specific examples below. The following examples are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the following examples.

[0073] The following will be described by way of specific examples. Unless otherwise specified, the raw materials are in parts by weight.

[0074] Preparation Example 1

[0075] (1) Dissolve 1.2 parts of MAH, 1.2 parts of St, 0.12 parts of BPO, and 0.12 parts of DCP in 3 times the volume of acetone solvent, and stir well at room temperature to prepare a solution.

[0076] (2) Use a high-speed mixer to heat 25 parts of EMA, 0.5 parts of antioxidant 1010, 0.3 parts of antioxidant 168, 0.4 parts of calcium stearate, and 0.4 parts of pentaerythritol stearate to 80 - 100 °C with high-speed stirring, then add the solution prepared in the first step and continue stirring for 5 - 10 min. Control the temperature below 100 °C throughout the process to promote the infiltration of the solution mixed with graft monomers and initiators into the toughening agent.

[0077] (3) Uniformly mix the second-step mixture with 35 parts of nylon 12-A using a low-speed stirrer and add it to the main feed port. The remaining 35.8 parts of nylon 12-A are added through the fifth side feed port. The screw length-diameter ratio is 48:1, the extrusion temperature is 250 - 270 °C, the screw speed is 600 rpm, and the vacuum degree is 0.05 MPa to obtain the in-situ graft toughening agent masterbatch A.

[0078] Preparation Example 2

[0079] Prepare the in-situ graft toughening agent masterbatch B according to the method in Preparation Example 1, with the difference that the toughening agent EMA is replaced by the toughening agent POE.

[0080] Preparation Example 3

[0081] Prepare the in-situ graft toughening agent masterbatch C according to the method in Preparation Example 1, with the difference that the graft monomers are changed from 1.2 parts of MAH and 1.2 parts of St to 2.4 parts of MAH, and the initiators are changed from 0.12 parts of BPO and 0.12 parts of DCP to 0.24 parts of DCP.

[0082] Preparation Comparative Example 1

[0083] Mix 35 parts of nylon 12-A, 27.6 parts of graft toughening agent GMA-g-MAH, 0.5 parts of antioxidant 1010, 0.3 parts of antioxidant 168, 0.4 parts of calcium stearate, and 0.4 parts of pentaerythritol stearate evenly using a low-speed stirrer, and feed them into a twin-screw extruder through the main feed port for pelletizing. The remaining nylon 12-A is added through the fifth side feed port. The screw length-diameter ratio is 48:1, the extrusion temperature is 250 - 270 °C, the screw speed is 400 rpm, and the vacuum degree is 0.05 MPa to obtain the graft toughening agent masterbatch D.

[0084] Preparation Comparative Example 2

[0085] Prepare the in-situ graft toughening agent masterbatch E according to the method in Comparative Example 1, with the difference that: replace the graft toughening agent GMA-g-MAH with POE-g-MAH.

[0086] Prepare Example 4

[0087] Prepare the in-situ graft toughening agent masterbatch F according to the method in Preparation Example 1, with the difference that: replace nylon 12-A with nylon 12-B.

[0088] Prepare Comparative Example 3

[0089] Prepare the in-situ graft toughening agent masterbatch G according to the method in Preparation Example 1, with the difference that: replace nylon 12-A with nylon 12-C

[0090] Prepare Example 5

[0091] (1) Mix 30 parts of the in-situ graft toughening agent masterbatch A and 10 parts of acrylic acid-modified polytetrafluoroethylene evenly by a high-speed mixer, then transfer them to the kneading section of a continuous kneader and knead for 3 minutes. Then add 50 parts of MCA and 10 parts of APP and knead for 5 minutes to obtain a lump-like kneaded material. The kneader speed is 60 rpm, and the kneader temperature is 210 °C;

[0092] (2) Feed the kneaded lump-like material into the twin-screw section of the continuous kneader through forced feeding, and granulate it after melt extrusion to obtain the in-situ fibrillated flame retardant masterbatch A. The screw length-diameter ratio is 8:1; the extrusion temperature is 210-220 °C; the screw speed is 200 rpm.

[0093] Prepare Example 6

[0094] Prepare the in-situ fibrillated flame retardant masterbatch B according to the method in Preparation Example 5, with the difference that: replace the synergistic flame retardant APP with an equal amount of ADP.

[0095] Prepare Comparative Example 4

[0096] Prepare the in-situ fibrillated flame retardant masterbatch C according to the method in Preparation Example 5, with the difference that: replace polytetrafluoroethylene with an equal amount of the in-situ graft toughening agent masterbatch A.

[0097] Prepare Comparative Example 5

[0098] Prepare the in-situ fibrillated flame retardant masterbatch D according to the method in Preparation Example 6, with the difference that: replace the in-situ graft toughening agent masterbatch A with an equal amount of nylon 12-A.

[0099] Prepare Comparative Example 6

[0100] Mix 30 parts of in-situ graft toughening agent masterbatch A and 10 parts of acrylic acid modified polytetrafluoroethylene evenly through a low-speed stirrer, and feed them into a twin-screw extruder through the main feeding port for pelletizing. After mixing 50 parts of MCA and 10 parts of APP well, add them through the fifth side feeding port. The length-diameter ratio of the screw is 48:1, the extrusion temperature is 210 - 220 °C, the screw speed is 400 rpm, and the vacuum degree is 0.05 MPa to obtain in-situ fibrillated flame retardant masterbatch E.

[0101] Example 1

[0102] Mix 59 parts of nylon 12-A, 20 parts of in-situ graft toughening agent masterbatch A, 0.25 parts of antioxidant 1010, 0.25 parts of antioxidant 168, 0.25 parts of calcium stearate, and 0.25 parts of pentaerythritol stearate evenly, and add them through the main feeding port. Add 20 parts of in-situ fibrillated flame retardant masterbatch A through the side feeding port, and use a twin-screw extruder for pelletizing. The length-diameter ratio of the screw is 48:1, the extrusion temperature is 240 - 250 °C, and the screw speed is 400 rpm.

[0103] Example 2

[0104] Prepare the halogen-free flame retardant modified nylon 12 material according to the method in Example 1, with the difference that: replace in-situ graft toughening agent masterbatch A with in-situ graft toughening agent masterbatch B.

[0105] Example 3

[0106] Prepare the halogen-free flame retardant modified nylon 12 material according to the method in Example 1, with the difference that: replace in-situ graft toughening agent masterbatch A with in-situ graft toughening agent masterbatch C.

[0107] Comparative Example 1

[0108] Prepare the halogen-free flame retardant modified nylon 12 material according to the method in Example 1, with the difference that: replace in-situ graft toughening agent masterbatch A with in-situ graft toughening agent masterbatch D.

[0109] Comparative Example 2

[0110] Prepare the halogen-free flame retardant modified nylon 12 material according to the method in Example 1, with the difference that: replace in-situ graft toughening agent masterbatch A with in-situ graft toughening agent masterbatch E.

[0111] Example 4

[0112] Prepare the halogen-free flame retardant modified nylon 12 material according to the method in Example 1, with the difference that: replace in-situ graft toughening agent masterbatch A with in-situ graft toughening agent masterbatch F.

[0113] Comparative Example 3

[0114] Prepare the halogen-free flame-retardant modified nylon 12 material according to the method in Example 1, with the difference that: replace the in-situ graft toughening agent masterbatch A with the in-situ graft toughening agent masterbatch G.

[0115] Example 5

[0116] Prepare the halogen-free flame-retardant modified nylon 12 material according to the method in Example 1, with the difference that: replace the in-situ fibrillating flame retardant masterbatch A with the in-situ fibrillating flame retardant masterbatch B.

[0117] Comparative Example 4

[0118] Prepare the halogen-free flame-retardant modified nylon 12 material according to the method in Example 1, with the difference that: replace the in-situ fibrillating flame retardant masterbatch A with the in-situ fibrillating flame retardant masterbatch C.

[0119] Comparative Example 5

[0120] Prepare the halogen-free flame-retardant modified nylon 12 material according to the method in Example 1, with the difference that: replace the in-situ fibrillating flame retardant masterbatch A with the in-situ fibrillating flame retardant masterbatch D.

[0121] Comparative Example 6

[0122] Prepare the halogen-free flame-retardant modified nylon 12 material according to the method in Example 1, with the difference that: replace the in-situ fibrillating flame retardant masterbatch A with the in-situ fibrillating flame retardant masterbatch E.

[0123] Example 6

[0124] Prepare the halogen-free flame-retardant modified nylon 12 material according to the method in Example 1, with the difference that: change the amount of the in-situ graft toughening agent masterbatch A from 20 parts to 30 parts.

[0125] Comparative Example 7

[0126] Prepare the halogen-free flame-retardant modified nylon 12 material according to the method in Example 1, with the difference that: change the amount of the in-situ fibrillating flame retardant masterbatch A from 20 parts to 30 parts.

[0127] Comparative Example 8

[0128] Prepare the halogen-free flame-retardant modified nylon 12 material according to the method in Example 1, with the difference that: replace the in-situ graft toughening agent masterbatch A with an equal amount of nylon 12-A.

[0129] Comparative Example 9

[0130] Mix 65 parts of nylon 12-A, 20 parts of in-situ graft toughening agent masterbatch A, 0.25 part of antioxidant 1010, 0.25 part of antioxidant 168, 0.25 part of calcium stearate, 0.25 part of pentaerythritol stearate, and 1 part of polytetrafluoroethylene evenly, and add them through the main feeding port. After mixing 10 parts of main flame retardant MCA and 3 parts of synergistic flame retardant APP evenly, add them through the side feeding port. Granulation is carried out using a twin-screw extruder with a screw length-diameter ratio of 48:1, an extrusion temperature of 240 - 250 °C, and a screw speed of 400 rpm.

[0131] The performance tests of the examples and comparative examples will be carried out according to the following standards or methods: The tensile properties are inspected according to the ISO527 standard, where the test speed for tensile strength is set at 5 mm / min and the test speed for tensile modulus is set at 1 mm / min; The notched impact strength is inspected according to the ISO179 standard, where the low-temperature notched impact test is carried out after freezing the notched sample at -30 °C for 4 h; The flame retardant performance is tested for 0.8 mm samples according to the UL94 standard; At the same time, the samples are aged for 7 days under the conditions of 85 °C / 85% RH (double 85), the surface precipitation of the flame retardant is observed, and the flame retardant performance is tested.

[0132] The test results of the halogen-free flame retardant modified nylon 12 prepared in Examples 1 - 7 and Comparative Examples 1 - 8 are as follows:

[0133] Table 1 - Performance comparison of halogen-free flame retardant modified nylon 12 materials in examples and comparative examples

[0134]

[0135]

[0136] It can be seen from the test results in Table 1 that a halogen-free flame retardant modified nylon 12 material with good impact strength, flame retardant performance and anti-precipitation characteristics can be obtained through the above formula composition and preparation method. The nylon 12 resin, in-situ graft toughening agent masterbatch, in-situ fibrillating flame retardant masterbatch components and preparation methods, etc. will all have different degrees of influence on the material properties.

[0137] The comparison of Examples 1, 2 and 3 shows that the materials prepared by using in-situ graft toughening agent masterbatch and in-situ fibrillating flame retardant masterbatch have high impact, V0 flame retardant and anti-precipitation characteristics.

[0138] The comparison of Example 1 with Comparative Examples 1 and 2 shows that directly using graft toughening agents has an adverse effect on the impact strength, flame retardant performance and anti-precipitation characteristics, especially in the case of directly using POE-based graft toughening agents.

[0139] The comparison between Example 4 and Comparative Example 3 shows that for the high-end amino content nylon 12 resin, although a relatively high impact strength is obtained, after the polar monomer of the graft toughening agent completely reacts with the end groups of the nylon 12 resin, it is not conducive to the bonding between the graft toughening agent and the flame retardant, thus having a negative impact on the flame retardancy and exudation situation.

[0140] The comparison between Example 5 and Comparative Example 4 shows that removing the in-situ fibrillating substance during the preparation of the flame retardant masterbatch has a relatively serious negative impact on the flame retardancy and exudation resistance characteristics due to the absence of the in-situ microfibril network.

[0141] The comparison between Example 5 and Comparative Example 5 shows that replacing the in-situ graft toughening agent masterbatch in the in-situ grafted flame retardant masterbatch with nylon 12 resin is not conducive to the dispersion of the flame retardant in the resin matrix. At the same time, due to the reduction of the graft toughening agent, the impact strength and flame retardant characteristics of the final material both show a significant decline.

[0142] The comparison between Example 5 and Comparative Example 6 shows that directly using a twin-screw extruder to melt-blend and prepare the in-situ grafted flame retardant masterbatch, due to the lack of sufficient conditions for the in-situ fibrillating substance to form a microfibril network, the flame retardant is not fully dispersed, so the flame retardancy and exudation resistance characteristics are poor.

[0143] The comparison between Example 6 and Comparative Example 7 shows that when the amount of the in-situ graft toughening agent masterbatch is increased to 30 parts, the impact strength does not increase further, and the flame retardancy decreases to a certain extent; while when the amount of the in-situ fibrillating flame retardant masterbatch is increased to 30 parts, the flame retardant slightly exudes after the double 85 aging, and the impact strength shows a significant decline.

[0144] The comparison between Example 6 and Comparative Example 8 shows that without adding the in-situ graft toughening agent masterbatch, both the impact strength and the flame retardancy are severely negatively affected.

[0145] The comparison between Example 6 and Comparative Example 9 shows that by skipping the preparation process of the in-situ fibrillating flame retardant masterbatch and directly adding the flame retardant, there are situations of uneven feeding and unstable flame retardant effect, which not only have a certain impact on the impact strength, but also are not conducive to the dispersion of the flame retardant in the resin and the formation of the in-situ microfibril network, ultimately having a serious negative effect on the flame retardancy and exudation problems.

[0146] It should be noted that the above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A high-impact resistant, non-halogenated flame-retardant modified nylon 12 material, by weight, comprises the following parts: Nylon 12 with a specific end group content, 35 - 85 parts, preferably 50 - 70 parts; In-situ graft toughener masterbatch, 10 - 40 parts, preferably 20 - 30 parts; In-situ fibrillation flame retardant masterbatch, 10 - 40 parts, preferably 20 - 30 parts; Processing aid, 0 - 4 parts, preferably 1 - 2 parts; Wherein, The amino - terminal content of the nylon 12 with specific end - group content is 10 - 50 mmol / kg, preferably 20 - 30 mmol / kg; the ratio of amino - terminal to carboxyl - terminal is 1:1 - 1:4, preferably 1:2 - 1:3; the number - average molecular weight ranges from 40000 to 50000, preferably 45000 - 48000; the polydispersity coefficient is 1.2 - 2.0, preferably 1.5 - 1.

8.

2. The modified nylon 12 material according to claim 1, characterized in that The in - situ grafting toughening agent masterbatch described above, by weight, comprises the following parts: Nylon 12 with specific end - group content, 40 - 80 parts, preferably 60 - 70 parts; Toughening agent, 10 - 40 parts, preferably 20 - 30 parts; Grafting monomer, 1 - 4 parts, preferably 2 - 3 parts; Initiator, 0.1 - 0.5 parts, preferably 0.2 - 0.3 parts; Processing aid, 0 - 3 parts, preferably 1 - 2 parts; Among them, the amino - terminal content of the nylon 12 with specific end - group content is 10 - 50 mmol / kg, preferably 20 - 30 mmol / kg; the ratio of amino - terminal to carboxyl - terminal is 1:1 - 1:4, preferably 1:2 - 1:3; the number - average molecular weight ranges from 40000 to 50000, preferably 45000 - 48000; the polydispersity coefficient is 1.2 - 2.0, preferably 1.5 - 1.

8.

3. The modified nylon 12 material according to claim 2, characterized in that The toughening agent is at least one of ethylene - octene copolymer, ethylene - propylene copolymer, ethylene - propylene - non - conjugated diene copolymer, styrene - butadiene copolymer, styrene - ethylene - butene - styrene block copolymer, ethylene - vinyl acetate copolymer, ethylene - acrylic acid copolymer, ethylene - ethyl acrylate copolymer, ethylene - methacrylic acid copolymer, ethylene - butyl acrylate.

4. The modified nylon 12 material according to claim 2, characterized in that The grafting monomer is one or several of maleic anhydride grafting and its derivatives, acrylate and its derivatives, methacrylic acid, unsaturated fatty acid, methylene succinic acid, glycidyl methacrylate, styrene, divinylbenzene, bismaleimide, triallyl isocyanurate, etc., preferably maleic anhydride and styrene are compounded in a weight ratio of 1:

1.

5. The modified nylon 12 material according to claim 1, characterized in that The processing aid comprises a lubricant and an antioxidant. The lubricant is one or several of polyethylene waxes, low - molecular - weight esters, metal soaps, stearic acid composite esters, amide waxes, montan waxes, low - viscosity bisphenol A epoxy resins, etc., preferably stearic acid composite esters and montan waxes are compounded in a weight ratio of 1:1; the antioxidant is one or several of copper salts, phosphates, hindered phenols, phosphites, thioesters, high - molecular - weight antioxidants, etc., preferably hindered phenols and phosphite antioxidants are compounded, and more preferably antioxidant 1098 and antioxidant 168 are compounded in a weight ratio of 1:

1.

6. The modified nylon 12 material according to claim 1, characterized in that The preparation method of the in - situ grafting toughening agent masterbatch described above comprises the following steps: (1) Dissolve the grafting monomer and the initiator in acetone to form a solution; (2) Stir with a high - speed mixer to heat the toughening agent to reach 80 - 100 °C, add the acetone solution containing the grafting monomer and the initiator and the processing aid, and control the temperature below 100 °C during the stirring process to promote the solution containing the grafting monomer and the initiator to penetrate into the toughening agent; (3) Feed the product of step (2) and 30 - 35 parts of nylon 12 with a specific end - group content into a twin - screw extruder through the main feed port for granulation, and add the remaining nylon 12 with a specific end - group content through the side feed port.

7. The modified nylon 12 material according to claim 1, characterized in that The in - situ fibrillating flame - retardant masterbatch described above, by weight, comprises the following components: In - situ grafting toughening agent masterbatch: 20 - 50 parts, preferably 30 - 40 parts; Main flame - retardant: 40 - 60 parts, preferably 40 - 50 parts; Synergistic flame - retardant: 5 - 20 parts, preferably 10 - 15 parts; In - situ fibrillating substance: 5 - 20 parts, preferably 10 - 15 parts.

8. The modified nylon 12 material according to claim 1, characterized in that The main flame - retardant is one or more of melamine cyanurate and melamine polyphosphate, and preferably melamine cyanurate with a particle size between 1.1 and 1.4 μm is used as the main flame - retardant; the synergistic flame - retardant is one or more of ammonium polyphosphate, aluminum diethyl phosphinate, aluminum hydroxide, magnesium hydroxide, pentaerythritol, zinc borate, expanded graphite, and chlorinated paraffin.

9. The preparation method according to claim 1, characterized in that The preparation method of the in - situ fibrillating flame - retardant masterbatch described above comprises the following steps: (1) Weigh the in - situ grafting toughening agent masterbatch and the in - situ fibrillating substance according to the ratio, mix them evenly through a high - speed mixer and then transfer them to the kneading section of a continuous mixer for kneading for 3 - 5 min, and then add the main flame - retardant and the synergistic flame - retardant and knead for 6 - 10 min to obtain a lump - shaped kneaded material; (2) Feed the lump - shaped kneaded material into the twin - cone screw section of the continuous mixer through forced feeding, and granulate after melting and extrusion to obtain the in - situ fibrillating flame - retardant masterbatch.

10. A method for preparing a high-impact halogen-free flame-retardant modified nylon 12 material according to claim 1, comprising the following steps: mixing a nylon 12 with a specific end group content, an in-situ graft toughening agent masterbatch, and a processing aid uniformly, adding them through the main feed port, adding an in-situ fibrillating flame retardant masterbatch from the side feed port, and granulating using a twin-screw extruder.

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