Polyamide composition and preparation method thereof

Abstract

The invention discloses a polyamide composition and a preparation method thereof. The polyamide composition is prepared from the following raw materials: PA66 resin, low dielectric glass fibers, PPO-g-MAH, a polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, functionalized POSS (Polyhedral Oligomeric Silsesquioxane), a DOPO (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) flame retardant and a high-temperature-resistant antioxidant. The polyamide composition has excellent mechanical properties, flame retardancy and low dielectric properties, and can be widely applied to the communication field requiring halogen-free flame retardancy.

Description

Technical Field

[0001] The invention belongs to the field of materials, and in particular relates to a polyamide composition and a preparation method thereof. Background Art

[0002] Polyamide 66 (PA66) is one of the most widely used engineering plastics. It has excellent mechanical properties, wear resistance, electrical insulation, chemical corrosion resistance and other advantages. It is widely used in electronics, transportation, construction and other fields. However, the limiting oxygen index (LOI) of PA66 is low (about 20% to 22%), it is easy to burn, and dripping occurs during the combustion process, which can easily cause serious fires, greatly limiting the application scope of PA66. Although halogen-containing flame retardants can effectively improve the flame retardancy of PA66, toxic substances will be produced during the flame retardant process, polluting the environment and causing great harm to human health. Therefore, the development of environmentally friendly and efficient flame retardant PA66 has become one of the research hotspots in recent years.

[0003] The flame retardants commonly used for halogen-free flame retardant modification of PA66 are divided into halogen-free organic flame retardants and inorganic flame retardants. Halogen-free organic flame retardants mainly include organic phosphorus, nitrogen, silicon and phosphorus-nitrogen synergistic flame retardants, which have the advantages of high flame retardant efficiency, low smoke and low toxicity; while inorganic flame retardants mainly include metal compounds, boron, inorganic phosphorus, expanded graphite and other flame retardants, which have the advantages of good heat resistance, non-volatility, long-lasting efficacy and low price. The flame retardant mechanism of flame retardants is usually divided into condensed phase flame retardant and gas phase flame retardant. Condensed phase flame retardant means that the flame retardant promotes the formation of the carbon layer, blocks oxygen and heat transfer, and achieves flame retardancy; gas phase flame retardant means that the free radicals released after the flame retardant is decomposed by heat slow down or terminate the flame chain reaction, and the non-combustible gas produced dilutes the concentration of oxygen and combustible gas in the combustion process, which has a flame retardant effect. In order to improve the flame retardant efficiency of flame retardants, flame retardants containing multiple flame retardant elements are usually designed to give full play to the synergistic flame retardant effects of the condensed phase and the gas phase to achieve high-efficiency flame retardancy of the flame retardant.

[0004] The most widely used electronic grade glass fiber in industry is alkali-free glass fiber, which has a dielectric constant of about 6.4 and a dielectric loss of about 10. -3 In the past decade, with the rapid development of the electronic information industry, the frequency of electromagnetic waves used in electronic devices has become higher and higher, and the energy density has become higher and higher. In order to reduce the lag and intensity attenuation of signal transmission, electronic grade glass fiber is required to have a lower dielectric constant (D k ≤5) and dielectric loss (D f ≤10 -3 ). This is because the smaller the dielectric constant, the faster the signal propagation speed, the smaller the dielectric loss, and the smaller the signal propagation loss.

[0005] At present, some research has been done on flame retardant polyamide compositions in the prior art. For example, Chinese patent CN112574559A discloses a high heat-resistant halogen-free flame retardant polyamide composite, which is prepared from the following raw materials in parts by weight: aliphatic polyamide: 10-60 parts; aromatic polyamide: 5-30 parts; halogen-free flame retardant: 10-30 parts; phenolic resin: 1-10 parts; glass fiber: 10-50 parts; antioxidant: 0.1-0.5 parts. The halogen-free flame retardant is a compound of aluminum diethylphosphinate, boehmite and zinc borate in a weight ratio of (15-16): (4-5): (2-3). Chinese patent CN104004350A discloses a glass fiber reinforced halogen-free flame retardant polyamide 6 composite material, which is blended by the following weight parts: 60-70 parts of polyamide 6 resin, 10-30 parts of glass fiber, 5-8 parts of flame retardant, 2-3 parts of flame retardant synergist, 6-12 parts of compatibilizer, 0.3-0.8 parts of antioxidant and 0.3-0.8 parts of lubricant. Among them, the flame retardant is any one of polyammonium polyphosphate, melamine, expanded graphite, melamine phosphate, TGIC, MCA or MPP, or any mixture of any of them in any proportion. Chinese patent CN 114672161A discloses a flame retardant polyamide composite material, which includes the following components by weight: 30-60 parts of polyamide; 17-30 parts of bromine-containing flame retardant; 9-30 parts of nylon 6I / 6T. Chinese patent CN 115850958A discloses a flame retardant polyamide elastomer material, comprising: 55-90 parts by weight of polyamide elastomer, 8-30 parts by weight of halogen-containing flame retardant, 2-15 parts by weight of antimony-containing synergistic flame retardant, and optionally, 0.2-2 parts by weight of coupling agent, 0.4-3 parts by weight of lubricant, and 0.1-2 parts by weight of antioxidant. It can be seen from the above patent that in the current prior art, the flame retardant technical effect of polyamide composition is mainly achieved by halogen-containing flame retardant or halogen-free flame retardant. However, none of the above patents involve adjusting the dielectric properties of flame retardant polyamide composition. Summary of the invention

[0006] Based on this, one of the purposes of the present invention is to provide a polyamide composition, which has excellent mechanical properties, flame retardant properties and low dielectric properties and can be widely used in the communication field requiring halogen-free flame retardancy.

[0007] The specific technical solutions for achieving the above-mentioned invention objectives include the following.

[0008] A polyamide composition is prepared from the following raw materials in parts by weight:

[0009]

[0010] The PPO-g-MAH is polyphenylene ether grafted with maleic anhydride; the functionalized POSS is functionalized polyhedral cage-type oligomeric silsesquioxane; the DOPO flame retardant is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; and the melting point of the high temperature resistant antioxidant is not less than 270°C.

[0011] In some embodiments, the polyamide composition is prepared from the following raw materials in parts by weight:

[0012]

[0013] In some embodiments, the polyamide composition is prepared from the following raw materials in parts by weight:

[0014]

[0015]

[0016] In some of the embodiments, the number average relative molecular mass of the PA66 resin is 22000-28000; the dielectric constant of the low dielectric glass fiber is 4.3-4.5 (test frequency is 1 GHz), and the glass fiber coating agent contains an amino group.

[0017] In some of the embodiments, the maleic anhydride grafting rate of the PPO-g-MAH is 1.0% to 1.4%.

[0018] In some of the embodiments, the end group of the functionalized POSS comprises an amino group; and the high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0019] In some of the embodiments, the preparation method of the polyborosiloxane polymer comprises the following steps: stirring 100g of hydroxyl-terminated polydimethylsiloxane, 18g-22g of boric acid and 20mL-30mL of anhydrous ethanol at 25°C-35°C for 10min-20min, then heating to 160°C-180°C, condensing and refluxing at a speed of 400rpm-600rpm for 6h-8h, then filtering under reduced pressure, and finally vacuum drying at 80°C-90°C for 22h-26h to obtain a polyborosiloxane polymer.

[0020] Another object of the present invention is to provide a method for preparing the polyamide composition.

[0021] The specific technical solutions for achieving the above-mentioned invention objectives include the following.

[0022] A method for preparing a polyamide composition comprises the following steps:

[0023] (1) drying the PA66 resin at a temperature of 110° C. to 130° C. for 2 to 4 hours, and then cooling the PA66 resin; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS, and a high temperature resistant antioxidant into a mixer for mixing;

[0024] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0025] (3) adding the mixed material prepared in step (1) to a parallel twin-screw extruder via a feeder, adding the mixed material prepared in step (2) to a side (e.g., the third zone) of the parallel twin-screw extruder (eight zones in total), and adding low dielectric glass fiber to the other side (e.g., the fourth zone) for melt extrusion and granulation, wherein the process parameters include: a temperature of zone 1 of 255° C. to 275° C., a temperature of zone 2 of 260° C. to 280° C., a temperature of zone 3 of 260° C. to 280° C., a temperature of zone 4 of 265° C. to 285° C., a temperature of zone 5 of 265° C. to 285° C., a temperature of zone 6 of 270° C. to 290° C., a temperature of zone 7 of 270° C. to 290° C., a temperature of zone 8 of 265° C. to 285° C., a die head temperature of 265° C. to 285° C., and a screw speed of 400 rpm to 800 rpm.

[0026] In some embodiments, the method for preparing the polyamide composition comprises the following steps:

[0027] (1) drying the PA66 resin at a temperature of 115° C. to 125° C. for 2.5 to 3.5 hours, and then cooling the PA66 resin; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS, and a high temperature resistant antioxidant into a mixer for mixing;

[0028] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0029] (3) adding the mixed material prepared in step (1) to a parallel twin-screw extruder via a feeder, adding the mixed material prepared in step (2) to a side (e.g., the third zone) of the parallel twin-screw extruder (eight zones in total), and adding low dielectric glass fiber to the other side (e.g., the fourth zone) for melt extrusion and granulation, wherein the process parameters include: a temperature of zone 1 of 260° C. to 270° C., a temperature of zone 2 of 265° C. to 275° C., a temperature of zone 3 of 265° C. to 275° C., a temperature of zone 4 of 270° C. to 280° C., a temperature of zone 5 of 270° C. to 280° C., a temperature of zone 6 of 275° C. to 285° C., a temperature of zone 7 of 275° C. to 285° C., a temperature of zone 8 of 270° C. to 280° C., a die head temperature of 270° C. to 280° C., and a screw speed of 500 rpm to 700 rpm.

[0030] In some of the embodiments, the screw shape of the parallel twin-screw extruder is a single-line thread; the ratio L / D of the screw length L and the diameter D is 35 to 55; the screw is provided with more than one (including one) meshing block area and more than one (including one) reverse thread area.

[0031] In some embodiments, the ratio L / D of the screw length L to the screw diameter D is 40-50; and the screw is provided with two meshing block areas and one reverse thread area.

[0032] In some of the embodiments, in step (1) and / or step (2), the stirrer is a high-speed stirrer with a rotation speed of 500 rpm-1500 rpm.

[0033] The functions of the various raw materials of the polyamide composition of the present invention are as follows:

[0034] Polyamide (PA) and polyphenylene oxide (PPO) occupy an important position in engineering plastics, but its own defects that cannot be ignored greatly limit the application field of the two. Therefore, by preparing polyamide and polyphenylene oxide to obtain polyamide / polyphenylene oxide alloy, the advantages of the two can be effectively combined. The alloy has the high heat resistance, high strength, high flame retardancy, low dielectricity of polyphenylene oxide and the solvent resistance and easy processing of polyamide at the same time, and realizes complementary advantages. However, polyamide belongs to polar crystalline resin, and polyphenylene oxide belongs to non-polar non-crystalline resin, and 2 kinds of incompatible polymers are simply blended, and the interface compatibility of the alloy obtained is poor, resulting in poor impact performance and tensile properties of simple blends. Therefore, the present invention is by blending PA66 and PPO-g-MAH, the terminal amino group of its PA66 and the maleic anhydride group of PPO-g-MAH can react, improve the compatibility and interface bonding between PA66 and PPO-g-MAH, thereby improving the mechanical properties and flame retardancy of polyamide composition, and reducing dielectric constant.

[0035] Low dielectric glass fiber belongs to a glass system with a high boron content. It has low loss, low density, low dielectric constant, and its dielectric properties are less affected by frequency and temperature. It also has wide bandwidth and high wave transmittance. Its dielectric constant is 4.3~4.5 (test frequency is 1GHz).

[0036] The present invention improves the flame retardant properties of a polyamide composition by compounding a polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, a functionalized POSS and a DOPO flame retardant. Among them, (1) the present invention obtains a polyborosiloxane polymer by a dehydration condensation reaction of hydroxyl-terminated polydimethylsiloxane and boric acid, which can simultaneously toughen and flame retard the polyamide composition. This is mainly because the polyborosiloxane polymer improves the melt strength of PA, participates in the formation of a highly expanded ceramic carbon layer, and improves the flame retardant properties of PA. At the same time, the polyborosiloxane polymer forms a micro-crosslinked island structure with PA through an esteramide exchange reaction, thereby toughening PA. (2) Hexaphenoxy cyclotriphosphazene belongs to a cyclophosphazene flame retardant, and has good thermal stability and flame retardant properties. Hexaphenoxy cyclotriphosphazene promotes PA to generate a dense carbon layer through acidic substances such as phosphoric acid and metaphosphoric acid generated by its own decomposition, thereby isolating oxygen in the air to achieve a flame retardant effect. At the same time, the nitrogen element in the hexaphenoxy cyclotriphosphazene will be converted into non-flammable gases such as NH3 during combustion, diluting the oxygen around PA. (3) Functionalized polyhedral cage oligomeric silsesquioxane (POSS) is a typical silicone flame retardant. Its composite flame retardant system can effectively flame retard polyamide compositions. The end groups of functionalized POSS contain amino groups, which can react with the end carboxyl groups of PA resins to improve the dispersibility and compatibility of functionalized POSS in PA resin materials, thereby improving the flame retardant properties of polyamide compositions. In addition, functionalized POSS has low dielectric properties (test frequency is 5 GHz, dielectric constant is 2.1-2.4), which is mainly because POSS has a three-dimensional structure similar to a cage, with an inorganic core formed by alternating silicon and oxygen (Si-O) at the center, and eight silicon atoms at the vertices connected to organic substituent groups (R groups). This cage structure allows a larger space inside the molecule, reduces the close packing between molecules, and reduces the polarization degree of the molecule. Under the action of an electric field, the molecule is not easily polarized, thereby reducing the dielectric constant. The bond energy of Si-O bond is higher (445.2 kJ / mol), which is more difficult to be broken than CC bond (350.7 kJ / mol) and CO bond (359.1 kJ / mol). Therefore, the vibration and rotation of Si-O bond are less affected in the electric field, which reduces the response to the electric field and thus reduces the dielectric constant. (4) 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is a synergistic flame retardant. On the one hand, the PO· free radicals produced by the thermal decomposition of DOPO capture the active free radicals HO· and H· in the gas phase during combustion, thereby inhibiting the free radical chain reaction and reducing the heat release. At the same time, some non-flammable gas is produced, thereby achieving the purpose of flame retardancy. On the other hand, when the polymer burns, DOPO will form phosphoric acid and polymetaphosphoric acid that promote carbonization, isolate oxygen and heat transfer, and achieve a flame retardant effect.

[0037] N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarboxamide is a high temperature resistant antioxidant with a melting point of 272°C. Its aromatic amine component can improve the thermal stability of the melt during polyamide processing, and the two piperidinyl groups in the molecule provide long-term thermal stability. At the same time, the amide group ensures high compatibility with the polyamide base material. The hindered piperidinyl group is a well-known part that plays a light stabilizing role. If it is attached to an oligomer or a high molecular weight skeleton, a better thermal stabilization effect can be obtained.

[0038] Compared with the prior art, the polyamide composition and preparation method thereof provided by the present invention have the following beneficial effects:

[0039] 1. The present invention improves the flame retardant properties of the polyamide composition by compounding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, functionalized POSS and DOPO flame retardant, and reduces the dielectric constant of the polyamide composition (usually using alkali-free glass fiber, whose dielectric constant is 6.3-6.5, and the test frequency is 1 GHz) by functionalized POSS and low dielectric glass fiber, and improves the compatibility and toughness of the polyamide composition by PPO-g-MAH and polyborosiloxane polymer, and the maleic anhydride group of PPO-g-MAH and the amino group of functionalized POSS and low dielectric glass fiber It can react with the end group of PA resin to improve the compatibility and interfacial adhesion between PA resin, low dielectric glass fiber and PPO-g-MAH, as well as improve the dispersibility and compatibility of polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, functionalized POSS and DOPO flame retardant in PA resin material, thereby improving the mechanical properties, flame retardant properties and low dielectric properties of the polyamide composition. The high temperature resistant antioxidant N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide is used to improve the thermal stability and oxidation resistance of the polyamide composition during processing and use.

[0040] 2. The preparation method of the polyamide composition of the present invention has simple process, is easy to control, has low requirements on equipment, and the equipment used is general polymer processing equipment, which has low investment and is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The present invention is a process flow chart of the preparation of the polyamide composition. DETAILED DESCRIPTION

[0042] In order to facilitate the understanding of the present invention, the present invention will be described more fully below in conjunction with the accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0043] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in the present invention includes any and all combinations of one or more of the related listed items.

[0044] The reaction mechanism of the polyamide composition of the present invention is as follows (see the preparation process flow chart Figure 1 ):

[0045]

[0046] Among them, R1 is functionalized POSS, or low dielectric glass fiber.

[0047] It can be seen from the above reaction formula that the maleic anhydride group of PPO-g-MAH and the amino groups of functionalized POSS and low dielectric glass fiber can react with the end group of PA resin, thereby improving the compatibility and interfacial adhesion between PA resin, low dielectric glass fiber and PPO-g-MAH, and improving the dispersibility and compatibility of polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, functionalized POSS and DOPO flame retardant in PA resin material, thereby preparing a polyamide composition having excellent mechanical properties, flame retardant properties and low dielectric properties.

[0048] The raw materials used in the examples and comparative examples of the present invention are as follows:

[0049] PA66 resin, with a number average relative molecular mass of 25,000, was purchased from Henan Shenma Nylon Chemical Co., Ltd.

[0050] Low dielectric glass fiber, with a dielectric constant of 4.4, and a glass fiber coating agent containing amino groups, was purchased from Taishan Glass Fiber Co., Ltd.

[0051] Alkali-free glass fiber with a dielectric constant of 6.4 was purchased from Taishan Glass Fiber Co., Ltd.

[0052] PPO-g-MAH, with a maleic anhydride grafting rate of 1.2%, was purchased from Jiayirong Polymer (Shanghai) Co., Ltd.

[0053] Hydroxyl-terminated polydimethylsiloxane was purchased from MacLean Chemical Reagent Co., Ltd.

[0054] Boric acid was purchased from MacLean Chemical Co., Ltd.

[0055] Anhydrous ethanol was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0056] Hexaphenoxycyclotriphosphazene was purchased from Wuhan Haishan Technology Co., Ltd.

[0057] Functionalized POSS, end groups containing amino groups, was selected from Hybrid Plastics Company, USA.

[0058] DOPO flame retardant was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0059] N,N'-Bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide was purchased from Clariant Chemicals GmbH, Germany.

[0060] The preparation method of the polyborosiloxane polymer used in the following examples and comparative examples comprises the following steps: adding 100 g of hydroxyl-terminated polydimethylsiloxane, 20 g of boric acid and 25 mL of anhydrous ethanol into a flask, stirring at 30° C. for 15 min, then heating the mixture to 170° C., and condensing and refluxing at a speed of 500 rpm for 7 h. Then, filtering under reduced pressure, and finally drying under vacuum at 85° C. for 24 h to obtain the polyborosiloxane polymer.

[0061] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0062] Example 1 Polyamide composition and preparation method thereof

[0063] The polyamide composition of this embodiment is prepared from the following raw materials in parts by weight:

[0064]

[0065]

[0066] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0067] Please refer to Figure 1 The method for preparing the polyamide composition of this embodiment comprises the following steps:

[0068] (1) drying the PA66 resin at 110° C. for 4 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS and a high temperature resistant antioxidant into a mixer for mixing;

[0069] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0070] (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: the temperature of zone 1 is 255° C., the temperature of zone 2 is 260° C., the temperature of zone 3 is 260° C., the temperature of zone 4 is 265° C., the temperature of zone 5 is 265° C., the temperature of zone 6 is 270° C., the temperature of zone 7 is 270° C., the temperature of zone 8 is 265° C., the die head temperature is 265° C., and the screw speed is 400 rpm.

[0071] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 35; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 500 rpm.

[0072] Example 2 Polyamide composition and preparation method thereof

[0073] The polyamide composition of this embodiment is prepared from the following raw materials in parts by weight:

[0074]

[0075]

[0076] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0077] The preparation method of the polyamide composition of the present embodiment comprises the following steps:

[0078] (1) drying the PA66 resin at 130° C. for 2 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS and a high temperature resistant antioxidant into a mixer for mixing;

[0079] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0080] (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: a temperature of 275° C. in zone 1, a temperature of 280° C. in zone 2, a temperature of 280° C. in zone 3, a temperature of 285° C. in zone 4, a temperature of 285° C. in zone 5, a temperature of 285° C. in zone 6, a temperature of 290° C. in zone 7, a temperature of 290° C. in zone 8, a die head temperature of 285° C., and a screw speed of 800 rpm.

[0081] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 55; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1500 rpm.

[0082] Example 3 Polyamide composition and preparation method thereof

[0083] The polyamide composition of this embodiment is prepared from the following raw materials in parts by weight:

[0084]

[0085]

[0086] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0087] The preparation method of the polyamide composition of the present embodiment comprises the following steps:

[0088] (1) drying the PA66 resin at 115° C. for 3.5 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS and a high temperature resistant antioxidant into a mixer for mixing;

[0089] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0090] (3) The mixed material prepared in step (1) is added to a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: the temperature of zone 1 is 260° C., the temperature of zone 2 is 265° C., the temperature of zone 3 is 265° C., the temperature of zone 4 is 270° C., the temperature of zone 5 is 270° C., the temperature of zone 6 is 275° C., the temperature of zone 7 is 275° C., the temperature of zone 8 is 270° C., the die head temperature is 270° C., and the screw speed is 500 rpm.

[0091] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 40; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 500 rpm.

[0092] Example 4 Polyamide composition and preparation method thereof

[0093] The polyamide composition of this embodiment is prepared from the following raw materials in parts by weight:

[0094]

[0095]

[0096] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0097] The preparation method of the polyamide composition of the present embodiment comprises the following steps:

[0098] (1) drying the PA66 resin at 125° C. for 2.5 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS and a high temperature resistant antioxidant into a mixer for mixing;

[0099] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0100] (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: the temperature of zone 1 is 270° C., the temperature of zone 2 is 275° C., the temperature of zone 3 is 275° C., the temperature of zone 4 is 280° C., the temperature of zone 5 is 280° C., the temperature of zone 6 is 285° C., the temperature of zone 7 is 285° C., the temperature of zone 8 is 280° C., the die head temperature is 280° C., and the screw speed is 700 rpm.

[0101] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 50; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1500 rpm.

[0102] Example 5 Polyamide composition and preparation method thereof

[0103] The polyamide composition of this embodiment is prepared from the following raw materials in parts by weight:

[0104]

[0105]

[0106] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0107] The preparation method of the polyamide composition of the present embodiment comprises the following steps:

[0108] (1) drying the PA66 resin at 120° C. for 3 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS and a high temperature resistant antioxidant into a mixer for mixing;

[0109] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0110] (3) The mixed material prepared in step (1) is added to a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265° C., a temperature of zone 2 of 270° C., a temperature of zone 3 of 270° C., a temperature of zone 4 of 275° C., a temperature of zone 5 of 275° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 275° C., a die head temperature of 275° C., and a screw speed of 600 rpm.

[0111] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0112] Example 6 Polyamide composition and preparation method thereof

[0113] The polyamide composition of this embodiment is prepared from the following raw materials in parts by weight:

[0114]

[0115]

[0116] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0117] The preparation method of the polyamide composition of the present embodiment comprises the following steps:

[0118] (1) drying the PA66 resin at 120° C. for 3 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS and a high temperature resistant antioxidant into a mixer for mixing;

[0119] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0120] (3) The mixed material prepared in step (1) is added to a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265° C., a temperature of zone 2 of 270° C., a temperature of zone 3 of 270° C., a temperature of zone 4 of 275° C., a temperature of zone 5 of 275° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 275° C., a die head temperature of 275° C., and a screw speed of 600 rpm.

[0121] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0122] Example 7 Polyamide composition and preparation method thereof

[0123] The polyamide composition of this embodiment is prepared from the following raw materials in parts by weight:

[0124]

[0125]

[0126] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0127] The preparation method of the polyamide composition of the present embodiment comprises the following steps:

[0128] (1) drying the PA66 resin at 120° C. for 3 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS and a high temperature resistant antioxidant into a mixer for mixing;

[0129] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0130] (3) The mixed material prepared in step (1) is added to a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265° C., a temperature of zone 2 of 270° C., a temperature of zone 3 of 270° C., a temperature of zone 4 of 275° C., a temperature of zone 5 of 275° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 275° C., a die head temperature of 275° C., and a screw speed of 600 rpm.

[0131] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0132] Comparative Example 1

[0133] The polyamide composition of this comparative example is prepared from the following raw materials in parts by weight:

[0134]

[0135]

[0136] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0137] The preparation method of the polyamide composition of this comparative example comprises the following steps:

[0138] (1) drying the PA66 resin at 120° C. for 3 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS and a high temperature resistant antioxidant into a mixer for mixing;

[0139] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0140] (3) adding the mixed material prepared in step (1) into a parallel twin-screw extruder via a feeder, adding the mixed material prepared in step (2) into a side (third zone) of the parallel twin-screw extruder (eight zones in total), and adding alkali-free glass fiber into the other side (fourth zone) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265° C., a temperature of zone 2 of 270° C., a temperature of zone 3 of 270° C., a temperature of zone 4 of 275° C., a temperature of zone 5 of 275° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 275° C., a die head temperature of 275° C., and a screw speed of 600 rpm.

[0141] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0142] Comparative Example 2

[0143] The polyamide composition of this comparative example is prepared from the following raw materials in parts by weight:

[0144]

[0145]

[0146] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0147] The preparation method of the polyamide composition of this comparative example comprises the following steps:

[0148] (1) drying the PA66 resin at 120° C. for 3 hours and then cooling it; adding the cooled PA66 resin, functionalized POSS and high temperature resistant antioxidant into a mixer for mixing;

[0149] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0150] (3) The mixed material prepared in step (1) is added to a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265° C., a temperature of zone 2 of 270° C., a temperature of zone 3 of 270° C., a temperature of zone 4 of 275° C., a temperature of zone 5 of 275° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 275° C., a die head temperature of 275° C., and a screw speed of 600 rpm.

[0151] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0152] Comparative Example 3

[0153] The polyamide composition of this comparative example is prepared from the following raw materials in parts by weight:

[0154]

[0155]

[0156] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0157] The preparation method of the polyamide composition of this comparative example comprises the following steps:

[0158] (1) drying the PA66 resin at 120° C. for 3 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS and a high temperature resistant antioxidant into a mixer for mixing;

[0159] (2) adding hexaphenoxy cyclotriphosphazene and DOPO flame retardant into another high-speed mixer and mixing;

[0160] (3) The mixed material prepared in step (1) is added to a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265° C., a temperature of zone 2 of 270° C., a temperature of zone 3 of 270° C., a temperature of zone 4 of 275° C., a temperature of zone 5 of 275° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 275° C., a die head temperature of 275° C., and a screw speed of 600 rpm.

[0161] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0162] Comparative Example 4

[0163] The polyamide composition of this comparative example is prepared from the following raw materials in parts by weight:

[0164]

[0165]

[0166] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0167] The preparation method of the polyamide composition of this comparative example comprises the following steps:

[0168] (1) drying the PA66 resin at 120° C. for 3 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS and a high temperature resistant antioxidant into a mixer for mixing;

[0169] (2) adding polyborosiloxane polymer and DOPO flame retardant into another high-speed mixer and mixing;

[0170] (3) The mixed material prepared in step (1) is added to a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265° C., a temperature of zone 2 of 270° C., a temperature of zone 3 of 270° C., a temperature of zone 4 of 275° C., a temperature of zone 5 of 275° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 275° C., a die head temperature of 275° C., and a screw speed of 600 rpm.

[0171] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0172] Comparative Example 5

[0173] The polyamide composition of this comparative example is prepared from the following raw materials in parts by weight:

[0174]

[0175]

[0176] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0177] The preparation method of the polyamide composition of this comparative example comprises the following steps:

[0178] (1) drying the PA66 resin at 120° C. for 3 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH and a high temperature resistant antioxidant into a mixer and mixing them;

[0179] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0180] (3) The mixed material prepared in step (1) is added to a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265° C., a temperature of zone 2 of 270° C., a temperature of zone 3 of 270° C., a temperature of zone 4 of 275° C., a temperature of zone 5 of 275° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 275° C., a die head temperature of 275° C., and a screw speed of 600 rpm.

[0181] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0182] Comparative Example 6

[0183] The polyamide composition of this comparative example is prepared from the following raw materials in parts by weight:

[0184]

[0185] The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0186] The preparation method of the polyamide composition of this comparative example comprises the following steps:

[0187] (1) drying the PA66 resin at 120° C. for 3 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS and a high temperature resistant antioxidant into a mixer for mixing;

[0188] (2) adding the polyborosiloxane polymer and hexaphenoxy cyclotriphosphazene into another high-speed mixer for mixing;

[0189] (3) The mixed material prepared in step (1) is added to a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265° C., a temperature of zone 2 of 270° C., a temperature of zone 3 of 270° C., a temperature of zone 4 of 275° C., a temperature of zone 5 of 275° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 275° C., a die head temperature of 275° C., and a screw speed of 600 rpm.

[0190] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0191] Comparative Example 7

[0192] The polyamide composition of this comparative example is prepared from the following raw materials in parts by weight:

[0193]

[0194] The preparation method of the polyamide composition of this comparative example comprises the following steps:

[0195] (1) drying the PA66 resin at 120° C. for 3 hours and then cooling it; adding the cooled PA66 resin, PPO-g-MAH and functionalized POSS into a mixer for mixing;

[0196] (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing;

[0197] (3) The mixed material prepared in step (1) is added to a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is added to the side (third zone) of the parallel twin-screw extruder (eight zones in total), and low dielectric glass fiber is added to the other side (fourth zone) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265° C., a temperature of zone 2 of 270° C., a temperature of zone 3 of 270° C., a temperature of zone 4 of 275° C., a temperature of zone 5 of 275° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 275° C., a die head temperature of 275° C., and a screw speed of 600 rpm.

[0198] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0199] The following is a table of raw material compositions of Examples 1-7 and Comparative Examples 1-7.

[0200] Table 1 List of raw material compositions of Examples 1-7 and Comparative Examples 1-7

[0201]

[0202]

[0203] Note: The high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide; a. The low dielectric glass fiber is replaced by alkali-free glass fiber.

[0204] Examples 1 to 7 are for preparing polyamide compositions by adjusting the addition amounts of PA66 resin, low dielectric glass fiber, PPO-g-MAH, polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, functionalized POSS, DOPO flame retardant, and high temperature resistant antioxidant. Comparative Example 1 is for replacing the low dielectric glass fiber with alkali-free glass fiber, Comparative Example 2 is for preparing a polyamide composition without adding PPO-g-MAH, Comparative Example 3 is for preparing a polyamide composition without adding polyborosiloxane polymer, Comparative Example 4 is for preparing a polyamide composition without adding hexaphenoxy cyclotriphosphazene, Comparative Example 5 is for preparing a polyamide composition without adding functionalized POSS, Comparative Example 6 is for preparing a polyamide composition without adding DOPO flame retardant, and Comparative Example 7 is for preparing a polyamide composition without adding a high temperature resistant antioxidant.

[0205] The polyamide compositions prepared in the above examples and comparative examples were subjected to the following performance tests:

[0206] Tensile strength: tested according to GB / T 1040-2006 standard, the tensile rate is 50mm / min.

[0207] Notched impact strength: tested in accordance with GB / T 1843-2008 standard.

[0208] Flame retardant performance: According to GB / T 2406.2-2009 standard test, the limiting oxygen index of the sample is determined by an oxygen index meter, and the sample size is 150mm×6.5mm×3mm.

[0209] Dielectric constant: Tested according to GB / T 5597-1999 standard, test frequency 5GHz.

[0210] The performance test results are shown in Table 2.

[0211] Table 2 Properties of polyamide compositions of Examples 1-7 and Comparative Examples 1-7

[0212]

[0213]

[0214] From Table 2 we can see that:

[0215] As the addition amount of low dielectric glass fiber and PPO-g-MAH increases, the tensile strength and notched impact strength of the polyamide composition gradually increase. This is because the low dielectric glass fiber plays a reinforcing role and PPO-g-MAH plays a toughening role.

[0216] As the amount of polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, functionalized POSS and DOPO flame retardant added increases, the flame retardant properties of the polyamide composition gradually improve. This is because, (1) the present invention obtains a polyborosiloxane polymer through a dehydration condensation reaction of hydroxyl-terminated polydimethylsiloxane and boric acid, which can simultaneously toughen and flame retard the polyamide composition. This is mainly because the polyborosiloxane polymer improves the melt strength of PA, participates in the formation of a highly expanded ceramic carbon layer, and improves the flame retardant properties of PA. At the same time, the polyborosiloxane polymer forms a micro-crosslinked island structure with PA through an esteramide exchange reaction, thereby toughening PA. (2) Hexaphenoxy cyclotriphosphazene belongs to a cyclophosphazene flame retardant, which has good thermal stability and flame retardant properties. Hexaphenoxy cyclotriphosphazene promotes the formation of a dense carbon layer in PA through the acidic substances such as phosphoric acid and metaphosphoric acid produced by its own decomposition, thereby isolating oxygen in the air to achieve a flame retardant effect. At the same time, the nitrogen element in hexaphenoxy cyclotriphosphazene will be converted into non-flammable gases such as NH3 during combustion, diluting the oxygen around PA. (3) Functionalized polyhedral cage oligomeric silsesquioxane (POSS) is a typical silicone flame retardant. Its composite flame retardant system can effectively flame retard polyamide compositions. The end groups of functionalized POSS contain amino groups, which can react with the end carboxyl groups of PA resins to improve the dispersibility and compatibility of functionalized POSS in PA resin materials, thereby improving the flame retardant properties of polyamide compositions. (4) 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is a synergistic flame retardant. On the one hand, the PO· free radicals generated by the thermal decomposition of DOPO capture the active free radicals HO· and H· in the gas phase during combustion, thereby inhibiting the free radical chain reaction, reducing the amount of heat release, and generating some non-flammable gases, thereby achieving the purpose of flame retardancy. On the other hand, when the polymer burns, DOPO will form phosphoric acid and polymetaphosphoric acid that promote carbonization, isolate oxygen and heat transfer, and achieve a flame retardant effect.

[0217] As the addition amount of low dielectric glass fiber, PPO-g-MAH and functionalized POSS increases, the dielectric constant of the polyamide composition decreases slightly. This is because the dielectric constant of low dielectric glass fiber is 4.3-4.5 (test frequency is 1 GHz), the dielectric constant of PPO-g-MAH is 2.6-2.7 (test frequency is 1 GHz), and the dielectric constant of functionalized POSS is 2.1-2.4 (test frequency is 5 GHz). Combined with the antagonistic effect of the above three, the dielectric constant of the polyamide composition decreases slightly.

[0218] In summary, by adjusting the addition amounts of PA66 resin, low dielectric glass fiber, PPO-g-MAH, polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, functionalized POSS, DOPO flame retardant, and high temperature resistant antioxidant, with the synergistic cooperation of various additives, the polyamide composition of the present invention with excellent mechanical properties, flame retardant properties and low dielectric properties can be obtained.

[0219] Compared with Example 7, in Comparative Example 1, the low dielectric glass fiber is replaced by alkali-free glass fiber. Since the low dielectric glass fiber belongs to a glass system with a high boron content, it has low loss, low density, low dielectric constant, and the dielectric properties are less affected by frequency and temperature, and has the characteristics of wide band and high wave transmission. Its dielectric constant is 4.3-4.5 (test frequency is 1 GHz), while the dielectric constant of alkali-free glass fiber is about 6.4. Therefore, the dielectric constant of Comparative Example 1 is higher than that of Example 7.

[0220] Compared with Example 7, Comparative Example 2 is a polyamide composition prepared without adding PPO-g-MAH. Since the present invention blends PA66 and PPO-g-MAH, the terminal amino group of PA66 and the maleic anhydride group of PPO-g-MAH can react, thereby improving the compatibility and interfacial adhesion between PA66 and PPO-g-MAH, thereby improving the mechanical properties and flame retardant properties of the polyamide composition and reducing the dielectric constant. Therefore, the tensile strength and notched impact strength of Comparative Example 2 are lower than those of Example 7, while the dielectric constant of Comparative Example 2 is higher than that of Example 7.

[0221] Compared with Example 7, Comparative Example 3 is a polyamide composition prepared without adding a polyborosiloxane polymer. Since the present invention obtains a polyborosiloxane polymer through a dehydration condensation reaction of a hydroxyl-terminated polydimethylsiloxane and boric acid, it can simultaneously toughen and flame retard the polyamide composition. This is mainly because the polyborosiloxane polymer improves the melt strength of PA, participates in the formation of a highly expanded ceramic carbon layer, and improves the flame retardant properties of PA. At the same time, the polyborosiloxane polymer forms a micro-crosslinked island structure with PA through an esteramide exchange reaction, thereby toughening PA. Therefore, the notched impact strength and flame retardant properties of Comparative Example 3 are lower than those of Example 7.

[0222] Compared with Example 7, Comparative Example 4 is a polyamide composition prepared without adding hexaphenoxy cyclotriphosphazene. Since hexaphenoxy cyclotriphosphazene is a cyclophosphazene flame retardant, it has good thermal stability and flame retardant properties. Hexaphenoxy cyclotriphosphazene promotes PA to generate a dense carbon layer through acidic substances such as phosphoric acid and metaphosphoric acid produced by its own decomposition, thereby isolating oxygen in the air to achieve a flame retardant effect. At the same time, the nitrogen element in hexaphenoxy cyclotriphosphazene will be converted into non-flammable gases such as NH3 during combustion, diluting the oxygen around PA. Therefore, the flame retardant performance of Comparative Example 4 is lower than that of Example 7.

[0223] Compared with Example 7, Comparative Example 5 prepares polyamide composition without adding functionalized POSS, because functionalized polyhedral cage type oligomeric silsesquioxane (POSS) is a typical organosilicon-based flame retardant, its composite flame retardant system can effectively flame retardant polyamide composition, and the end group of functionalized POSS comprises amino group, its amino group can react with the terminal carboxyl group of PA resin, improve the dispersibility and compatibility of functionalized POSS in PA resin material, thus improve the flame retardant property of polyamide composition. In addition, functionalized POSS has low dielectric properties (test frequency is 5GHz, and dielectric constant is 2.1~2.4), this is mainly because POSS has the three-dimensional structure of similar cage, center is the inorganic kernel formed by alternate connection of silicon oxygen (Si-O), and the silicon atom of eight vertices is connected to organic substituted group (R group). This cage structure makes molecular interior have larger space, reduces the close packing between molecules, reduces the polarization degree of molecule. Under electric field action, molecule is not easily polarized, thus reduces dielectric constant. The bond energy of Si-O bond is higher (445.2 kJ / mol), which is more difficult to be destroyed than CC bond (350.7 kJ / mol) and CO bond (359.1 kJ / mol). Therefore, the vibration and rotation of Si-O bond are less affected in the electric field, which reduces the response to the electric field and thus reduces the dielectric constant. Therefore, the flame retardant performance of comparative example 5 is lower than that of example 7, while the dielectric constant of comparative example 5 is higher than that of example 7.

[0224] Compared with Example 7, Comparative Example 6 is a polyamide composition prepared without adding DOPO flame retardant. Since 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is used as a synergistic flame retardant, on the one hand, the PO· free radicals generated by the thermal decomposition of DOPO capture the active free radicals HO· and H· in the gas phase during combustion, thereby inhibiting the free radical chain reaction, reducing the heat release, and generating some non-flammable gas, thereby achieving the purpose of flame retardancy. On the other hand, DOPO will form phosphoric acid and polymetaphosphoric acid that promote carbonization when the polymer burns, isolating oxygen and heat transfer, and achieving a flame retardant effect. Therefore, the flame retardant performance of Comparative Example 6 is lower than that of Example 7.

[0225] Compared with Example 7, Comparative Example 7 is a polyamide composition prepared without adding a high temperature resistant antioxidant. Since N, N'-bis (2,2,6,6-tetramethyl-4-piperidinyl) -1,3-benzenedicarboxamide is a high temperature resistant antioxidant with a melting point of 272°C, its aromatic amine component can improve the thermal stability of the melt during the polyamide processing, and the two piperidinyl groups in the molecule provide long-term thermal stability, while the amide group ensures high compatibility with the polyamide base material. The hindered piperidinyl group is a well-known part that plays a light stabilizing role. If it is attached to an oligomer or a high relative molecular mass skeleton, a better thermal stabilization effect can be obtained. Therefore, the tensile strength and notched impact strength of Comparative Example 7 are lower than those of Example 7.

[0226] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0227] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A polyamide composition, characterized in that It is prepared from the following raw materials in parts by weight: PA66 resin 70 to 90 parts Low dielectric glass fiber 10 to 30 parts The total weight of PA66 resin and low dielectric glass fiber is 100 parts. The PPO-g-MAH is polyphenylene ether grafted with maleic anhydride; the functionalized POSS is functionalized polyhedral cage-type oligomeric silsesquioxane; the DOPO flame retardant is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; and the melting point of the high temperature resistant antioxidant is not less than 270°C.

2. The polyamide composition according to claim 1, characterized in that It is prepared from the following raw materials in parts by weight: PA66 resin 75 to 85 parts Low dielectric glass fiber 15 to 25 parts The total weight of PA66 resin and low dielectric glass fiber is 100 parts.

3. The polyamide composition according to claim 2, characterized in that It is prepared from the following raw materials in parts by weight: PA66 resin 78 to 82 parts Low dielectric glass fiber 18 to 22 parts The total weight of PA66 resin and low dielectric glass fiber is 100 parts.

4. The polyamide composition according to any one of claims 1 to 3, characterized in that The number average relative molecular mass of the PA66 resin is 22000-28000; and / or the dielectric constant of the low dielectric glass fiber is 4.3-4.5, and the glass fiber coating agent contains an amino group.

5. The polyamide composition according to any one of claims 1 to 3, characterized in that The maleic anhydride grafting rate of the PPO-g-MAH is 1.0% to 1.4%; and / or the end group of the functionalized POSS contains an amino group; and / or the high temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

6. The polyamide composition according to any one of claims 1 to 3, characterized in that The preparation method of the polyborosiloxane polymer comprises the following steps: stirring 100g of hydroxyl-terminated polydimethylsiloxane, 18g-22g of boric acid and 20mL-30mL of anhydrous ethanol at 25°C-35°C for 10min-20min, then heating to 160°C-180°C, condensing and refluxing at 400rpm-600rpm for 6h-8h, then filtering under reduced pressure, and finally drying under vacuum at 80°C-90°C for 22h-26h to obtain the polyborosiloxane polymer.

7. A method for preparing a polyamide composition according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) drying the PA66 resin at a temperature of 110° C. to 130° C. for 2 to 4 hours, and then cooling; Add the cooled PA66 resin, PPO-g-MAH, functionalized POSS and high temperature resistant antioxidant into a mixer for mixing; (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing; (3) adding the mixed material prepared in step (1) into a parallel twin-screw extruder via a feeder, adding the mixed material prepared in step (2) to a side of the parallel twin-screw extruder, and adding low dielectric glass fiber to the other side for melt extrusion and granulation, wherein the process parameters include: a temperature of zone 1 of 255° C. to 275° C., a temperature of zone 2 of 260° C. to 280° C., a temperature of zone 3 of 260° C. to 280° C., a temperature of zone 4 of 265° C. to 285° C., a temperature of zone 5 of 265° C. to 285° C., a temperature of zone 6 of 270° C. to 290° C., a temperature of zone 7 of 270° C. to 290° C., a temperature of zone 8 of 265° C. to 285° C., a die head temperature of 265° C. to 285° C., and a screw speed of 400 rpm to 800 rpm.

8. The preparation method according to claim 7, characterized in that: The following steps are involved: (1) drying the PA66 resin at a temperature of 115° C. to 125° C. for 2.5 to 3.5 hours, and then cooling the PA66 resin; adding the cooled PA66 resin, PPO-g-MAH, functionalized POSS, and a high temperature resistant antioxidant into a mixer for mixing; (2) adding polyborosiloxane polymer, hexaphenoxy cyclotriphosphazene, and DOPO flame retardant into another high-speed mixer and mixing; (3) adding the mixed material prepared in step (1) into a parallel twin-screw extruder via a feeder, adding the mixed material prepared in step (2) to a side of the parallel twin-screw extruder, and adding low dielectric glass fiber to the other side for melt extrusion and granulation, wherein the process parameters include: a temperature of zone 1 of 260° C. to 270° C., a temperature of zone 2 of 265° C. to 275° C., a temperature of zone 3 of 265° C. to 275° C., a temperature of zone 4 of 270° C. to 280° C., a temperature of zone 5 of 270° C. to 280° C., a temperature of zone 6 of 275° C. to 285° C., a temperature of zone 7 of 275° C. to 285° C., a temperature of zone 8 of 270° C. to 280° C., a die head temperature of 270° C. to 280° C., and a screw speed of 500 rpm to 700 rpm.

9. The preparation method according to claim 7 or 8, characterized in that: The screw shape of the parallel twin-screw extruder is a single-threaded screw; and / or the ratio L / D of the screw length L and the diameter D of the parallel twin-screw extruder is 35 to 55; and / or the screw of the parallel twin-screw extruder is provided with more than one meshing block area and more than one reverse thread area; in step (1) and / or step (2), the mixer is a high-speed mixer with a rotation speed of 500 rpm-1500 rpm.

10. The preparation method according to claim 9, characterized in that: The ratio L / D of the screw length L to the diameter D of the parallel twin-screw extruder is 40-50; and / or, the screw of the parallel twin-screw extruder is provided with two meshing block areas and one reverse thread area.

Images