CN115895246A - Expandable graphite modified polyamide elastomer material and preparation method and application thereof - Google Patents

Abstract

The invention discloses an expandable graphite-modified polyamide elastomer material, a preparation method and application thereof. The polyamide elastomer material modified by expandable graphite, based on the total weight of 100 parts, includes: 45-74 parts of polyamide elastomer, 15-40 parts of expandable graphite flame retardant, 8-40 parts of synergistic flame retardant 25 parts, 0.3-3 parts of coupling agent, 0.5-3 parts of dispersant, 0.1-2 parts of antioxidant, 0.1-2 parts of absorbent. The polyamide elastomer flame retardant material modified by expandable graphite of the present invention can reach UL94‑V0 level in flame retardancy, tensile strength is 27‑43MPa, impact strength is ^above 20KJ/m2, and is suitable for the preparation of auto parts .

Description

Expandable graphite-modified polyamide elastomer material and preparation method and application thereof

Technical Field

The invention belongs to the field of elastomer composite materials, and in particular relates to an expandable graphite-modified polyamide elastomer material and a preparation method and application thereof.

Background Art

The trend of lightweight automobiles and the popularity of new energy vehicles have put forward higher mechanical and flame retardant performance requirements for flame retardant materials used to prepare automotive parts such as ball couplings, dust covers, shockproof parts, fenders, anti-skid chains, etc.

Most of the halogen-free flame retardant materials on the market are made by adding or blending organic or inorganic flame retardants into base materials. However, while achieving flame retardant properties, the mechanical properties of the materials (such as tensile strength and impact properties) are greatly reduced. In addition, base materials with poor performance themselves, such as rubber and some elastomer materials used in most of the prior art, cannot be recycled or have low mechanical and aging resistance, resulting in flame retardant materials with poor flexibility, high hardness, difficulty in recycling, poor compatibility with flame retardants, etc., making it difficult to meet the use requirements of certain specific environments. For example, polyurethane elastomers (TPU), which are currently being studied more, are difficult to use in the preparation of the above-mentioned automotive parts due to their insufficient mechanical properties.

Polyamide elastomer (TPAE), also known as thermoplastic polyamide elastomer, is a block copolymer containing a polyamide hard segment and an aliphatic polyester or polyether soft segment. TPAE can be divided into two categories according to hardness: polyether block amide (PEBA) with aliphatic polyamide as the hard segment, and other TPAE with semi-aromatic polyamide as the hard segment, such as polyether ester amide (PEEA), polyester amide (PEA) and polycarbonate amide (PCEA). Although TPAE has the characteristics of low hardness, good flexibility, high tensile strength, good elastic recovery, high low-temperature impact strength, and excellent low-temperature resistance, the existing polyamide elastomers still have the disadvantages of low oxygen index, easy combustion, and poor mechanical properties when used as flame retardant materials, which limits its application in the automotive field.

Summary of the invention

The present invention aims to solve the deficiencies in the prior art. By subjecting polyamide elastomer (TPAE) to expandable graphite flame retardant modification, the prepared expanded flame retardant elastomer material has the advantages of high efficiency flame retardancy, excellent mechanical properties, green environmental protection, low cost and recyclability. The expanded flame retardant elastomer material can be used for the preparation of automotive spherical couplings, dust covers, shockproof components, fenders and other parts.

Based on the above objectives, the first aspect of the present invention provides an expandable graphite modified polyamide elastomer material, which comprises, based on 100 parts of the total weight: 45-74 parts of polyamide elastomer, 15-40 parts of expandable graphite flame retardant, 8-25 parts of synergistic flame retardant, 0.3-3 parts of coupling agent, 0.5-3 parts of dispersant, 0.1-2 parts of antioxidant, and 0.1-2 parts of absorbent.

Preferably, the expandable graphite modified polyamide elastomer material, based on a total weight of 100 parts, comprises: 50-70 parts of polyamide elastomer, 15-30 parts of expandable graphite flame retardant, 10-20 parts of synergistic flame retardant, 0.4-1 part of coupling agent, 0.6-1.5 parts of dispersant, 0.1-1 part of antioxidant, and 0.1-0.6 part of absorbent; more preferably, based on a total weight of 100 parts, comprises: 60-68 parts of polyamide elastomer, 20-25 parts of expandable graphite flame retardant, 10-15 parts of synergistic flame retardant, 0.4-0.8 part of coupling agent, 0.8-1.2 parts of dispersant, 0.3-0.8 part of antioxidant, and 0.2-0.5 part of absorbent.

In some embodiments, the polyamide elastomer is one or more selected from long-chain or short-chain polyether block amide (PEBA), polyether ester amide (PEEA), polyester amide (PEA) and polycarbonate amide (PCEA) block copolymers; preferably a short-chain polyether block polyamide elastomer; more preferably a nylon 6 type polyether block polyamide elastomer (i.e., polyamide 6 type thermoplastic elastomer, TPAE-6).

In the present invention, the long-chain polyether block amide refers to a polyether block amide in which the hard segment polyamide is synthesized from a long carbon chain nylon, such as nylon 10, nylon 1010, nylon 11, nylon 12, etc. The short-chain polyether block amide refers to a polyether block amide in which the hard segment polyamide is synthesized from a short carbon chain nylon relative to the long-chain nylon, such as nylon 6, etc.

In some embodiments, the relative viscosity of the polyamide elastomer is 1.5-3.0, preferably 2.0-2.8 (determined by GB/T12006.1 (ISO307) standard method with formic acid solution as solvent), and the hardness is 25D-60D (determined by GB/T2411-2008 standard method), so as to take into account both the processing flowability and mechanical properties of the composite material.

In some embodiments, the nylon 6 type polyether block polyamide elastomer is a polyamide 6 thermoplastic elastomer resin prepared by the method of patent CN104327266B, and the method comprises the following steps:

Add polyether/polyester, caprolactam, deionized water, catalyst and diacid into a reactor, heat to 200-240° C. under nitrogen protection, and react for 0.5-2 hours under mechanical stirring; then evacuate to 20-500 Pa at 250-280° C. and continue to react for 0.5-3 hours under mechanical stirring; then extract with boiling water and dry to obtain polyamide 6 thermoplastic elastomer resin, wherein the diacid is oxalic acid, malonic acid, succinic acid or adipic acid, and the catalyst is phosphoric acid, sulfuric acid, or aminocaproic acid.

Preferably, in the preparation method of the nylon 6 type thermoplastic elastomer resin as described above, the polyester/polyether is one or more selected from polytetrahydrofuran (PTMEG), polyethylene glycol (PEG), polypropylene glycol (PPG) or polyethylene glycol. Preferably, the number average molecular weight of the polyester/polyether is 300-8000, preferably 500-6000. Preferably, based on the total weight of the polyether/polyester and caprolactam, the amount of the polyester/polyether soft segment is 10wt-60wt%. Preferably, based on the total weight of the polyether/polyester and caprolactam, the amount of the caprolactam is 40wt-90wt%; and/or the amount of the diacid is 1-10wt%; and/or, the amount of the catalyst is 0.1-4wt%, preferably 1-3wt%; and/or the amount of the deionized water is 0.5-4wt%, preferably 1-3wt%. Preferably, the mechanical stirring speed is 100-800rpm.

The relative viscosity of the nylon 6 thermoplastic elastomer resin prepared by this method is between 1.5 and 3.0 (determined by the GB/T12006.1 (ISO307) standard method with formic acid solution as solvent), and a stable viscosity can be obtained by more precise adjustment of the reaction temperature and time.

In particular, the structure of the nylon 6 type polyether block polyamide elastomer is as follows:

{[CO-(CH ₂ ) ₅ -HN] _m -CO-(CH ₂ ) ₄ -COO-PE} _n

Wherein, PE represents a soft segment polyester or polyether, such as polyethylene glycol (PEG), tetramethylene glycol ether (PTMG), propylene oxide polyether (PPG), polycaprolactone (PCL), etc., and its number average molecular weight is 300-8000, preferably 500-6000;

m＝6-100, n＝2-15.

Preferably, in the nylon 6 type thermoplastic elastomer resin described above, the content of the nylon 6 hard segment accounts for 40wt% to 90wt% of the total amount of the polymer hard segment and the soft segment; the content of the polyether/polyester soft segment accounts for 10wt% to 60wt% of the total amount of the polymer hard segment and the soft segment.

The nylon 6 type polyether block polyamide elastomer has a short carbon chain, a relatively high nitrogen content, and a more excellent flame retardant property. The nylon 6 type polyether block polyamide elastomer contains a large number of terminal amino groups and terminal carboxyl groups, and has a strong polarity. In the presence of a coupling agent, it has good compatibility with an expanded graphite flame retardant and a synergistic flame retardant, forming a strong hydrogen bond, which can greatly improve the mechanical properties and flame retardancy of the composite flame retardant material.

In some embodiments, the expandable graphite is selected from medium initial expansion temperature graphite or high initial expansion temperature expandable graphite, preferably medium initial expansion temperature expandable graphite, and the expansion temperature is not less than 250° C. In this preferred case, it not only has cost advantages, but also has better performance than high initial expansion temperature expandable graphite.

In the present invention, medium initial expansion temperature graphite generally refers to expanded graphite with an initial expansion temperature of 150°C-290°C; high initial expansion temperature graphite generally refers to expanded graphite with an initial expansion temperature higher than 290°C.

In some embodiments, the expandable graphite particle size is 30-100 mesh, preferably 80 mesh, and the expandability is not less than 200 times, preferably not less than 230 times.

In some embodiments, the synergistic flame retardant is one or more selected from magnesium hydroxide (MDH), aluminum hydroxide (ATH), red phosphorus (RP), ammonium polyphosphate (APP), triphenyl phosphate (TPP), basic magnesium sulfate whisker, and silicon dioxide whisker. The synergistic flame retardant can increase the amount of residual carbon and improve the quality of the carbon layer to improve the flame retardant efficiency and minimize the cost.

Preferably, the synergistic flame retardant is aluminum hydroxide (ATH). Aluminum hydroxide decomposes under heat and not only absorbs heat, inhibits the temperature rise and degradation rate of the material, but also produces water vapor that can dilute the combustible gas; at the same time, the decomposition product is non-combustible, and can increase the amount of residual carbon and enhance the strength of the expanded carbon layer to avoid the "wick effect".

In some embodiments, the mass ratio of the synergistic flame retardant to the expandable graphite flame retardant is 1:1 to 1:3. Within the ratio range, it is beneficial to achieve more efficient flame retardancy through high carbonization and expanded network skeleton.

In some embodiments, the coupling agent is one or more selected from silane coupling agents and titanate coupling agents.

Preferably, the silane coupling agent is selected from KH560, KH550, KH570, KH792, DL602, and the titanate coupling agent is 201, 101, 105, 311, TTS; more preferably, the coupling agent is silane coupling agent KH560. The epoxy group in the alkyl coupling agent KH560 reacts with the terminal amino group and the terminal carboxyl group of TPAE6, and its methoxyl group is hydrolyzed to generate Si-OH group, which is condensed with inorganic materials such as expandable graphite, ATH, _SiO2 , etc.

In some embodiments, the coupling agent is used in an amount of 0.5% to 3.5% of the total mass of the flame retardant; within the said ratio range, it is beneficial to improve the adhesion between the flame retardant and the polyamide elastomer, thereby improving the comprehensive mechanical and anti-aging properties of the product.

In some embodiments, the dispersant is selected from ethylene bisstearamide (EBS), stearic acid monoglyceride, tristearic acid glyceride, polyethylene wax, liquid paraffin, metal salts of higher fatty acids such as barium stearate, calcium stearate, zinc stearate, etc., pentaerythritol stearate, preferably ethylene bisstearamide (EBS).

In some embodiments, the antioxidant is selected from hindered phenols, hindered amines and phosphite antioxidants, preferably one or more of antioxidant 168, antioxidant 608, antioxidant 1010, antioxidant 1076, antioxidant 1098, antioxidant 3114, antioxidant 164, antioxidant 264, antioxidant BHT, antioxidant T501, antioxidant B215, antioxidant B225, more preferably antioxidant 1098 and antioxidant 168 or a combination thereof.

In some embodiments, the absorbent is a mixture of one or more selected from nano titanium dioxide, porous silicate, diatomaceous earth, zinc ricinoleate, zinc sulfate, and nano zinc oxide; preferably porous silicate; the porous silicate includes natural porous silicates such as natural zeolite, kaolinite and artificial porous silicates such as artificial zeolite, ceramics, magnesium silicate, etc.

Expandable graphite will produce a small amount of SO ₂ during expansion, which may have a slight impact on the environment. The present invention adds a small amount of absorbent to absorb SO ₂ while preventing flame retardancy, thereby avoiding the impact of flame retardant materials on the environment and achieving halogen-free, non-toxic, green and environmentally friendly effects.

In some embodiments, the mass ratio of the absorbent to the expandable graphite is 10:1000 to 25:1000, and the preferred mass ratio is 15:1000 to 20:1000. Within the ratio range, it is beneficial to achieve the absorption of expandable graphite acidic gas and combustion decomposition activity and harmful gases, thereby improving flame retardant efficiency and environmental protection effects.

The second aspect of the present invention provides a method for preparing the above-mentioned expandable graphite-modified polyamide elastomer material, which is selected from the processing methods of internal mixing single-screw extrusion granulation, conical twin-screw granulation, side-feeding parallel twin-screw granulation, planetary extrusion granulation, and reciprocating screw extrusion granulation, preferably internal mixing single-screw extrusion granulation.

In some embodiments, the method for preparing the expandable graphite-modified polyamide elastomer material comprises the following steps:

S1: Mix expandable graphite, synergistic flame retardant, coupling agent and compatibilizer while heating to a certain temperature and then stop mixing to allow the coupling agent and flame retardant to fully react;

S2: Add polyamide elastomer resin, dispersant, antioxidant and absorbent, continue mixing for a while, and then take out the material;

S3: placing the mixed materials in an internal mixer for internal mixing to obtain a molten mixture of expandable graphite-modified polyamide elastomer material;

S4: The molten mixture is extruded and granulated in an extruder to obtain an expandable graphite-modified polyamide elastomer material.

In some embodiments, in step S1, the mixing is based on the temperature, and the mixing is stopped when the temperature reaches 60-80°C.

In some embodiments, in step S1, the temperature is increased while mixing by high-speed mixing friction heating, and the high-speed mixing speed is 850-1440 r/min; or, the temperature is increased while mixing by heating high-speed mixing, and the mixing time to reach the specified temperature is controlled in the range of 5-15 minutes, preferably 10-12 minutes.

In some embodiments, in step S2, the mixing time is 3-10 min, preferably 3-5 min. In some embodiments, in step S3, the banburying temperature is 150-180°C.

In some embodiments, in step S4, the temperature of extrusion granulation is 160-210°C.

The processing temperature provided in the preparation method of the present invention cannot be too high and cannot exceed the decomposition temperature of the expandable graphite.

The third aspect of the present invention provides the use of the above expandable graphite-modified polyamide elastomer material in the preparation of automobile parts.

Preferably, the automobile parts include a spherical coupling, a dust cover, an anti-vibration component, a mudguard, and an anti-skid chain.

Beneficial Effects

1. The present invention adopts polyamide elastomer, especially nylon 6 type polyether block polyamide elastomer as a substrate, expandable graphite and aluminum hydroxide (ATH) as a flame retardant system, and adds a suitable coupling agent and dispersant to prepare a polyamide elastomer flame retardant material. The expanded flame retardant material has a large expansion ratio of the heated surface, a thick carbon layer, a high flame retardant efficiency, is halogen-free, low-smoke, non-toxic, green and environmentally friendly, and has excellent mechanical properties.

2. The expandable graphite-modified polyamide elastomer flame retardant material of the present invention has a flame retardant property of up to UL94-V0, a tensile strength of 27-43MPa, and an impact strength of more than 20KJ/ ^m2 , and is suitable for the preparation of automotive parts.

3. The preparation method of the present invention has simple process, low production cost and is convenient for large-scale production.

DETAILED DESCRIPTION

The present invention will be understood by reference to the following examples, which are intended to illustrate the present invention and are not to be construed as limiting the scope of the present invention in any way.

The flame retardant material of the present invention is an expandable flame retardant system composed of expandable graphite and synergistic flame retardant. Expandable graphite is a relatively new type of flame retardant in the current halogen-free flame retardant technology. It mainly uses chemical and physical methods to insert intercalants (such as acids, alkali metals, salts and other chemical substances) into the carbon hexagonal network plane structure between graphite layers, thereby forming a crystalline compound. In actual use, the principle of the flame retardant is as follows: when the crystalline compound is heated, the interlayer inserted material will decompose or gasify due to the heat, thereby generating a large amount of expansion heat. Because the expansion heat is much greater than the van der Waals force in the graphite space, the flakes will be expanded by the airflow, and the distance between the graphites will be further expanded, thus forming a "worm-like" expanded graphite, thereby forming a very thick porous carbonized layer covering the surface of the substrate. The carbonized layer has sufficient thermal stability to separate the flame retardant body from the heat source, thereby delaying and terminating the decomposition of the polymer. At the same time, the acid radicals in the interlayer are released during expansion, which also promotes the carbonization of the substrate, thereby achieving good results through a variety of flame retardant methods. Moreover, the material itself is non-toxic, does not produce toxic and corrosive gases when heated, and can greatly reduce the amount of smoke. At the same time, the synergistic flame retardant aluminum hydroxide decomposes when heated, absorbs heat from the environment, inhibits the temperature rise and degradation rate of the material, and the water vapor produced by its decomposition can also dilute the combustible gas; at the same time, the decomposition products are non-combustible, and can increase the amount of residual carbon and enhance the strength of the expanded carbon layer, avoiding the "wick effect".

Reagents:

Homemade TPAE6: Homemade polyamide elastomer resin TPAE-6 (relative viscosity about 2.0), prepared by the preparation method of Example 2 of patent CN104327266B, the specific preparation steps are as follows:

Add 20g of polyethylene glycol with a number average molecular weight of 2000, 80g of caprolactam, 3g of deionized water, 3g of sulfuric acid and 1g of adipic acid into the reactor, heat to 240°C under nitrogen protection, and react for 1.5 hours with mechanical stirring at 800rpm; then, evacuate to 40Pa at 260°C and continue to react for 2.5 hours with mechanical stirring at 800rpm, then extract with boiling water and dry.

Expandable graphite: EG-X200, particle size 80 mesh, expansion ratio ≥≥230, initial expansion temperature>250℃, Qingdao Yanhai Graphite Co., Ltd.

Aluminum hydroxide (ATH): FR-3801, whiteness ≥97, particle size D ₅₀ 1.5-2.0 μm, Hefei Zhongke Flame Retardant New Materials Co., Ltd.

Ethylene bis stearamide (EBS): EB-FF model, Dongguan Shanyi Plastics Co., Ltd.

Polyurethane elastomer (TPU): WHT-8254 Wanhua Chemical.

Other TPAE6 was purchased from: Arkema PEBAX HD5513.

Coupling agent KH560: FT-560 from Nanjing Feiteng New Material Technology Co., Ltd.

Antioxidant 1098/168: BASF 1098 and 168 from Dinghai Plastic Chemical Co., Ltd.

Absorbent porous silicate: magnesium silicate MS10E from Tianjin Yitailong Additive Co., Ltd.

equipment:

High-speed mixer: HSM-50 Jiangsu Bell Machinery;

Internal mixer single screw integrated machine: Changfeng CF-10L from Dongguan Changfeng Machinery Technology Co., Ltd.

Injection molding machine: UN120SM Guangdong Yizumi Precision Machinery Co., Ltd.

Electronic universal material testing machine: Zwick/Roell Z020 Shanghai Zwick Machinery Equipment Co., Ltd.;

Horizontal and vertical combustion tester: CZF-5 Beijing AVIC Times Instrument Equipment Co., Ltd.

Pendulum impact tester: Zwick/RoellHIT50P Shanghai Zwick Machinery Equipment Co., Ltd.;

Notching instrument: B1120.26.10 Shanghai Zweck Machinery Equipment Co., Ltd.

Example 1

This embodiment provides a method for preparing an expandable graphite-modified polyamide elastomer material, comprising the following steps:

(1) 15 parts by weight of expandable graphite, 15 parts by weight of ATH, and 0.4 parts by weight of silane coupling agent KH560 (which can be diluted with 95% vol ethanol when added, the content represents the content before dilution, and the dilution volume ratio KH560:95% ethanol=1:5) are added into a high-speed mixer in a spray form, and the temperature is increased while mixing in a high-speed mixing friction heating manner, and the high mixing speed is 1250 r/min. After the temperature reaches 70° C., the mixing is stopped to obtain a flame retardant mixture with a surface treatment;

(2) 68.2 parts by weight of homemade TPAE6, 0.6 parts by weight of EBS, 0.5 parts by weight of an antioxidant mixture (0.2 parts by weight of 1098 and 0.3 parts by weight of 168), and 0.3 parts by weight of an absorbent magnesium silicate were added to the surface-treated flame retardant mixture, and the mixture was fully blended in a high-speed mixer for 3 to 5 minutes, and the mixture was discharged to obtain an expanded flame-retardant polyamide elastomer raw material mixture.

(3) Add the above-mentioned expanded flame retardant polyamide elastomer raw material mixture into an internal mixer, and melt-mix it in a temperature range of 150 to 180° C. to obtain an expanded flame retardant polyamide elastomer molten mixture.

(4) Add the above-mentioned expanded flame-retardant polyamide elastomer molten mixture into a single-screw extruder, and perform extrusion granulation in a temperature range of 160 to 210° C. to obtain an expanded flame-retardant polyamide elastomer material.

Embodiment 2-6

The polyamide elastomer material was prepared by the method of Example 1, except that the amounts of the components were different, as shown in Table 1.

Table 1 Raw material components for preparing polyamide elastomer materials in Examples 1-6

Example Homemade TPAE6 Expandable graphite ATH KH560 EBS Antioxidants Absorbent Total 1 68.2 15 15 0.4 0.6 0.5 0.3 100 2 57.6 20 20 0.5 1 0.5 0.4 100 3 62.6 25 10 0.5 1 0.5 0.4 100 4 49.2 30 18 0.6 1.2 0.5 0.5 100 5 65.7 20 12 0.5 1 0.5 0.3 100 6 46.6 35 15 0.8 1.5 0.5 0.6 100

Comparative Example 1-2:

The intumescent flame retardant material was prepared by the method of Example 1, except that the homemade TPAE6 substrate was replaced by the commercially available TPAE6 polyamide elastomer PEBAX HD 5513 or the commercially available polyurethane elastomer TPU (WHT-8254). The remaining components and their amounts are shown in Table 2.

Table 2 Raw material components for preparing intumescent flame retardant materials in Comparative Examples 1-8

Comparative Examples 3-8

Comparative Examples 3-8 use the method of Example 1 to prepare polyamide elastomer flame retardant materials, except that the components do not contain expandable graphite, ATH or KH560, or the expandable graphite, ATH and KH560 in the components exceed the scope of protection required by the present invention. The specific components are shown in Table 2.

Experimental Example 1 Mechanical properties and flame retardant properties test:

The flame retardant properties and mechanical properties of the composite materials of Examples 1-6 and Comparative Examples 1-8 were tested, and the performance evaluation method and test standard were as follows:

The extruded granulated composite material was dried at 90° C. for 1 to 2 hours, and then the test samples were molded using an injection molding machine equipped with a standard test specimen mold (each group of samples contained 5 tensile and impact test specimens and 10 flame retardant test specimens).

Mechanical properties test: According to the ASTM D638-2003 plastic tensile properties test standard of the American Society for Testing and Materials, the tensile properties of the composite materials were tested using a universal tensile testing machine. At least 5 parallel samples were guaranteed for each group of tensile tests, and the results were averaged. According to the ISO180-2001 plastic cantilever beam impact standard, the composite materials were tested, and at least 5 parallel samples were guaranteed for each group of impact tests, and the results were averaged (pendulum impact tester, notch tester).

Flame retardant performance test: The open flame flame retardant performance was tested according to the UL94-2006 standard, and the sample standard was 125x13x1.6mm (horizontal vertical combustion tester).

The test results are shown in Table 3.

Table 3 Flame retardant properties and mechanical test results of intumescent flame retardant materials

As shown in Table 3, it can be seen from Examples 1-6 that in the flame retardant polyamide elastomer system of ATH synergistic expandable graphite, adding 15-40% by weight of expandable graphite can achieve the flame retardant effect of UL94-V0, and the flame retardant polyamide elastomer is low-smoke, halogen-free and environmentally friendly, and has excellent mechanical properties. It is an ideal flame retardant elastomer material for preparing automotive parts.

In Comparative Examples 1 and 2, the commonly used TPAE6 PEBAX HD5513 and polyurethane elastomer WHT-8254 on the market were used to prepare the expandable flame retardant material. When the elastomers had the same addition and proportion, the flame retardant properties were equivalent to those of the homemade TPAE6, but the tensile strength was inferior to that of the flame retardant composite material based on the polyamide elastomer, indicating the good mechanical property advantages of the homemade TPAE6.

In Comparative Examples 3, 4, and 7, when the main flame retardant expandable graphite, synergist ATH, and coupling agent KH560 are missing from the intumescent flame retardant system, the flame retardant effect and mechanical properties of the system are very unsatisfactory. Similarly, in Comparative Examples 5, 6, and 8, the ratio of the intumescent flame retardant system substrate polyamide 6 elastomer, the main flame retardant expandable graphite, the synergist ATH, and the coupling agent KH560 is not within the scope of protection claimed by the present invention, and the flame retardant effect or mechanical properties of the system are unsatisfactory.

It can be seen that through the selection of resin substrate, expandable graphite flame retardant and ATH synergistic flame retardant, and the addition of suitable types and amounts of coupling agents and dispersants, the expandable graphite-modified polyamide elastomer material of the present invention can show an excellent balance between flame retardant properties and mechanical properties, and is green, environmentally friendly and low-cost.

Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the claims. Any technical personnel in this field may make several possible changes and modifications without departing from the concept of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims of the present application.

Claims (10)

1. An expandable graphite-modified polyamide elastomer material, characterized in that the expandable graphite-modified polyamide elastomer material, based on 100 parts of the total weight, comprises: 45 to 74 parts of polyamide elastomer, 15 to 40 parts of expandable graphite flame retardant, 8 to 25 parts of synergistic flame retardant, 0.3 to 3 parts of coupling agent, 0.5 to 3 parts of dispersant, 0.1-2 parts of antioxidant, and 0.1-2 parts of absorbent. 2. The expandable graphite-modified polyamide elastomer material according to claim 1 is characterized in that the expandable graphite-modified polyamide elastomer material, based on a total weight of 100 parts, comprises: 50 to 70 parts of polyamide elastomer, 15 to 30 parts of expandable graphite flame retardant, 10 to 20 parts of synergistic flame retardant, 0.4 to 1 part of coupling agent, 0.6 to 1.5 parts of dispersant, 0.1-1 part of antioxidant, and 0.1-0.6 part of absorbent; preferably, based on a total weight of 100 parts, comprises: 60 to 68 parts of polyamide elastomer, 20 to 25 parts of expandable graphite flame retardant, 10 to 15 parts of synergistic flame retardant, 0.4 to 0.8 part of coupling agent, 0.8 to 1.2 parts of dispersant, 0.3-0.8 part of antioxidant, and 0.2-0.5 part of absorbent. 3. The expandable graphite-modified polyamide elastomer material according to claim 1 or 2, characterized in that the polyamide elastomer is one or more selected from long-chain or short-chain polyether block amide, polyether ester amide, polyester amide and polycarbonate amide block copolymer; preferably a short-chain polyether block polyamide elastomer; more preferably a nylon 6 type polyether block polyamide elastomer; Preferably, the polyamide elastomer has a relative viscosity of 1.5-3.0, preferably 2.0-2.8, and a hardness of 25D-60D. 4. The expandable graphite-modified polyamide elastomer material according to claim 3, characterized in that the preparation method of the nylon 6 type polyether block polyamide elastomer comprises the following steps: Add polyether/polyester, caprolactam, deionized water, catalyst and diacid into a reactor, heat to 200-240° C. under nitrogen protection, and react for 0.5-2 hours under mechanical stirring; then evacuate to 20-500 Pa at 250-280° C. and continue to react for 0.5-3 hours under mechanical stirring; then extract with boiling water and dry to obtain polyamide 6 thermoplastic elastomer resin, wherein the diacid is oxalic acid, malonic acid, succinic acid or adipic acid, and the catalyst is phosphoric acid, sulfuric acid, or aminocaproic acid; Preferably, the polyester/polyether is one or more selected from polytetrahydrofuran, polyethylene glycol, polypropylene glycol or polyethylene glycol; Preferably, the number average molecular weight of the polyester/polyether is 300-8000; Preferably, based on the total weight of the polyether/polyester and caprolactam, the amount of the polyester/polyether soft segment is 10wt% to 60wt%; Preferably, based on the total weight of polyether/polyester and caprolactam, the amount of caprolactam is 40wt~90wt%; and/or the amount of diacid is 1~10wt%; and/or the amount of catalyst is 0.1~4wt%; and/or the amount of deionized water is 0.5~4wt%; preferably, the mechanical stirring speed is 100~800rpm. 5. The expandable graphite-modified polyamide elastomer material according to claim 1 or 2, characterized in that the expandable graphite is selected from medium initial expansion temperature graphite or high initial expansion temperature expandable graphite, preferably medium initial expansion temperature expandable graphite, and the expansion temperature is not less than 250°C; Preferably, the expandable graphite particle size is 30-100 mesh, preferably 80 mesh, and the expandability is not less than 200 times, preferably not less than 230 times; And/or, the synergistic flame retardant is one or more selected from magnesium hydroxide, aluminum hydroxide, red phosphorus, ammonium polyphosphate, triphenyl phosphate, basic magnesium sulfate whisker, silicon dioxide whisker, preferably aluminum hydroxide; Preferably, the mass ratio of the synergistic flame retardant to the expandable graphite flame retardant is 1:1 to 1:3. 6. The expandable graphite-modified polyamide elastomer material according to claim 1 or 2, characterized in that the coupling agent is one or more selected from silane coupling agents and titanate coupling agents; Preferably, the silane coupling agent is selected from KH560, KH550, KH570, KH792, DL602, and the titanate coupling agent is 201, 101, 105, 311, TTS; more preferably, the coupling agent is silane coupling agent KH560; Preferably, the coupling agent is used in an amount of 0.5% to 3.5% of the total mass of the flame retardant; And/or, the dispersant is selected from ethylene bisstearamide, stearic acid monoglyceride, tristearic acid glyceride, polyethylene wax, liquid paraffin, metal salts of higher fatty acids, pentaerythritol stearate, preferably, the metal salts of higher fatty acids include barium stearate, calcium stearate, zinc stearate; the dispersant is preferably ethylene bisstearamide. 7. The expandable graphite-modified polyamide elastomer material according to claim 1 or 2, characterized in that the antioxidant is selected from hindered phenols, hindered amines and phosphites, preferably one or more of antioxidant 168, antioxidant 608, antioxidant 1010, antioxidant 1076, antioxidant 1098, antioxidant 3114, antioxidant 164, antioxidant 264, antioxidant BHT, antioxidant T501, antioxidant B215, and antioxidant B225, more preferably antioxidant 1098 and antioxidant 168 or a combination thereof; And/or, the absorbent is a mixture of one or more selected from nano titanium dioxide, porous silicate, diatomaceous earth, zinc ricinoleate, zinc sulfate, and nano zinc oxide; preferably porous silicate; the porous silicate includes natural porous silicate and artificial porous silicate; preferably, the natural porous silicate is selected from natural zeolite and kaolinite, and the artificial porous silicate is selected from artificial zeolite, ceramic, and magnesium silicate; Preferably, the mass ratio of the absorbent to the expandable graphite is 10:1000 to 25:1000, and the preferred mass ratio is 15:1000 to 20:1000. 8. The method for preparing the expandable graphite-modified polyamide elastomer material according to any one of claims 1 to 7, characterized in that the preparation method is selected from the processing methods of internal mixing single-screw extrusion granulation, conical twin-screw granulation, side-feeding parallel twin-screw granulation, planetary extrusion granulation, and reciprocating screw extrusion granulation, preferably internal mixing single-screw extrusion granulation. 9. The preparation method according to claim 8, characterized in that the preparation method comprises the following steps: S1: Mix expandable graphite, synergistic flame retardant, coupling agent and compatibilizer while heating to a certain temperature and then stop mixing to allow the coupling agent and flame retardant to fully react; S2: Add polyamide elastomer resin, dispersant, antioxidant and absorbent, continue mixing for a while, and then take out the material; S3: placing the mixed materials in an internal mixer for internal mixing to obtain a molten mixture of expandable graphite-modified polyamide elastomer material; S4: extruding the molten mixture into granules in an extruder to obtain an expandable graphite-modified polyamide elastomer material; Preferably, in step S1, the mixing is based on the temperature, and the mixing is stopped when the temperature reaches 60-80°C; Preferably, in step S1, the temperature is increased while mixing by high-speed mixing friction heating, and the high-speed mixing speed is 850-1440 r/min; or, the temperature is increased while mixing by heating high-speed mixing, and the mixing time to reach the specified temperature is controlled in the range of 5-15 minutes, preferably 10-12 minutes; Preferably, in step S2, the mixing time is 3-10 min, preferably 3-5 min; Preferably, in step S3, the banburying temperature is 150-180°C; Preferably, in step S4, the temperature of extrusion granulation is 160-210°C. 10. Use of the expandable graphite-modified polyamide elastomer material according to any one of claims 1 to 7, or the expandable graphite-modified polyamide elastomer material prepared by the preparation method according to claim 8 or 9 in the preparation of automotive parts; Preferably, the automobile parts include a spherical coupling, a dust cover, an anti-vibration component, a mudguard, and an anti-skid chain.