CN117683345A

CN117683345A - Fireproof heat-resistant polyamide composition, and preparation method and application thereof

Info

Publication number: CN117683345A
Application number: CN202311746970.1A
Authority: CN
Inventors: 陈跃民; 贾红兵; 安琦; 董子宁; 韩佩瑶; 张翔
Original assignee: Jiangsu Ginar Plastic Technology Co ltd
Current assignee: Jiangsu Ginar Plastic Technology Co ltd
Priority date: 2023-12-19
Filing date: 2023-12-19
Publication date: 2024-03-12

Abstract

The invention discloses a fireproof heat-resistant polyamide composition, a preparation method and application thereof, wherein the composition comprises 20.0-50.0wt% of aliphatic polyamide; 5.0 to 20.0 weight percent of flame retardant; 10.0 to 30.0 weight percent of glass fiber; 20.0 to 50.0 weight percent of ceramic mineral; 3.0 to 10.0 weight percent of epoxy resin; 0.1 to 2.0 weight percent of latent curing agent; other auxiliary agents are less than or equal to 3.0wt%; the total weight of the components is 100 percent, the aliphatic polyamide is semi-crystalline polymer, the melting temperature is 150-300 ℃, and the aliphatic polyamide is obtained by heating, melting, blending and extruding through a screw extruder. The composition is a polyamide composite material which can replace aluminum alloy to dissipate heat, does not melt, drip or puncture after flame burning for at least 5 minutes, has certain structural strength after high temperature burning, and can provide enough time to leave a vehicle when thermal runaway occurs in a battery pack shell and a cover.

Description

Fireproof heat-resistant polyamide composition, and preparation method and application thereof

Technical Field

The invention belongs to the field of high polymer materials, and particularly relates to a fireproof heat-resistant polyamide composition, and a preparation method and application thereof.

Background

In recent years, the new energy automobile industry enters the vigorous development stage, a lithium battery is used on a large scale on a power battery by a new energy automobile enterprise, the lithium battery is a high energy body, and the charging and discharging of the lithium battery are a severe heating process, and thermal runaway is one of the most common potential safety hazards of the lithium battery, and is a main cause of internal short circuit, overcharge, overdischarge and Gao Wenshi thermal runaway. Thermal runaway of an electric automobile can cause combustion of a battery and ignition of surrounding parts, and even explosion occurs in severe cases.

The battery system is beneficial to ensuring that a driver has enough time to evacuate and extinguish fire after the battery monomer of the electric automobile is out of control in heat, which is required by the power storage battery safety requirement of GB 38031-2020 electric automobile, and the battery pack shell has excellent flame retardant property and can effectively delay flame spreading when the electric automobile is in fire. The improvement of regulation and safety standard accelerates the technical improvement of related products, further strengthens the product quality through technical innovation, and ensures the product safety.

Aluminum alloy is a main battery shell material at present, and has the advantages of high strength, excellent heat dissipation and the like, but the defects of the aluminum alloy are not ignored, the aluminum alloy shell has high specific gravity and complex manufacturing process flow, and aluminum has high chemical reactivity with water at high temperature, so that the aluminum alloy is difficult to extinguish with water when a fire disaster occurs, and a larger disaster can occur when the aluminum alloy is improperly treated. The traditional flame-retardant high polymer generally adopts bromine, inorganic phosphorus or organic phosphorus to provide a flame-inhibiting function, but the material can only support tens of seconds when being exposed to flame, and can not meet the requirements of thermal runaway application scenes of power batteries. In addition, the traditional flame-retardant polymer material has low heat conductivity coefficient, and is applied to a battery shell, so that the heat dissipation problem is also solved, and the service life of the battery is lost due to poor heat dissipation.

As one of the most ideal materials for the light-weight and high-efficiency structural design, the polyamide composite material has the advantages of high specific strength, corrosion resistance, fatigue resistance, good dimensional stability, strong designability and the like, and is very suitable for being applied to battery pack shells and covers instead of aluminum alloy. Flame retardant modified polyamide compositions are typically formulated with sufficient flame retardant to achieve flame inhibition, such as disclosed in patent CN110461929a for phosphinate flame retardant polyamide, CN103328572a for red phosphorus flame retardant polyamide, and CN102089373a for melamine cyanurate flame retardant polyamide. However, these conventional flame retardant polyamide composite materials can only resist flame ignition for several tens of seconds, and further improvement of flame retardant properties is required. Patent document CN113646162a discloses a flame-retardant heat-insulating material suitable for battery cells, which has a three-layer structure, wherein aramid and mica paper are respectively used as an outer layer, and an inner layer is felt or paper of inorganic short fibers, which can well block flame, but has the disadvantage of low design freedom of products. Patent document CN106133043a discloses a polyamide-based composition from the group of fillers comprising alumina, boron nitride and aluminum silicate for the manufacture of products with higher fire protection requirements, particularly preferably products with higher Glow Wire (GWFI) requirements. This polyamide composite material is adequate for contact glowing filament (GWFI) 960 ℃/30 seconds but is still a distance from the flame for more than 5 minutes. Patent document CN111892814a discloses a high-barrier fire-resistant halogen-free flame-retardant reinforced nylon composite material, by introducing linear phenolic resin into a phosphinate flame-retardant nylon system, the material forms a micro-crosslinking structure in the extrusion and injection molding processes, the density and strength of a carbon layer formed in the combustion process of the material can be improved, the heat insulation capacity is greatly improved, and phenolic resin is directly added in thermoplastic polymerization, so that the thermosetting efficiency is required to be improved.

The known molding compositions are still not sufficiently effective in delaying the flame spread and do not provide a composition which has sufficient structural strength in high temperature environments.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the main object of the present invention is to provide a fireproof and heat-resistant polyamide composition, which can replace aluminum alloy to dissipate heat, does not melt, drip or perforate even when flame burns for at least more than 5 minutes, and has a certain structural strength after high temperature and burning.

It is another object of the present invention to provide a process for preparing the flame-retardant and heat-resistant polyamide composition.

It is still another object of the present invention to provide the use of the flame-retardant and heat-resistant polyamide composition for the preparation of lithium battery housings and covers for new energy automobiles.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the invention provides a fireproof heat-resistant polyamide composition, which comprises the following components:

wherein the sum of components (A) to (G) is 100% by weight of the flame-retardant and heat-resistant polyamide composition.

Preferably, the aliphatic polyamide of component (A) is a semi-crystalline polymer having a melting temperature of 150 to 300℃and characterized by Differential Scanning Calorimetry (DSC) and a heating and cooling rate of 10℃per minute.

More preferably, the repeating unit of the aliphatic polyamide is selected from one or more monomers selected from aliphatic dicarboxylic acids and aliphatic diamines, lactams having not less than four carbon atoms; wherein:

the aliphatic dicarboxylic acid is selected from the group consisting of: oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, eicosanedioic acid;

the aliphatic diamine having not less than four carbon atoms is selected from the group consisting of: butanediamine, pentanediamine, ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecyldiamine, tetradecanediamine, pentadecylenediamine, hexadecanediamine, heptadecylenediamine, octadecanediamine, nonadecylenediamine, icosanediamine, 2-methyl-1, 8-octanediamine, 2, 4-trimethylhexamethylenediamine, 2, 4-trimethylhexamethylenediamine;

the lactam is selected from the group consisting of: epsilon-caprolactam, enantholactam, undecanolactam, dodecanolactam, alpha pyrrolidone, alpha piperidone.

In some preferred embodiments, the aliphatic polyamide and monomer are selected from one or more of the following tables:

aliphatic polyamide	Monomer(s)
		PA 6	Epsilon-caprolactam
PA 66	Hexamethylenediamine, adipic acid
		PA 610	Hexamethylenediamine and sebacic acid
PA 612	Hexamethylenediamine, dodecanedioic acid
		PA 46	Butanediamine, adipic acid
PA 56	Pentanediamine, adipic acid
		PA 1010	Decanediamine and decanedioic acid
PA 11	Undecanolactam
		PA 12	Lauryllactam

In some preferred embodiments, the aliphatic polyamide is PA66 and/or PA 6.

Preferably, the component (B) is a halogen-free flame retardant, and the halogen-free flame retardant is dialkyl phosphinate shown in the formula (I); or a mixture of a dialkylphosphinate represented by the formula (I) and a phosphite represented by the formula (II); or a mixture of dialkylphosphinate salts, melamine polyphosphate salts and zinc borate represented by the formula (I);

in the formula (I), R ¹ 、R ² Identical or different and representing a linear or branched C1-C6 alkyl group;

M ₁ represent Mg, ca, al, sb, sn, ge, ti, zn, fe, zr, ce, bi, sr, mn, li, na, K and/or protonated nitrogen bases; m represents an integer of 1 to 4; n represents an integer of 1 to 4;

in the formula (II), M ₂ Representation Mg, ca, al, sb, sn, ge, ti, zn, fe, zr, ce, bi, sr, mn, li, na, K; m represents the whole of 1 to 4A number.

Halogen-free flame retardants of the formulae (I) and (II) are described in patent CN103154110B and are commercially available.

More preferably, when the halogen-free flame retardant is a mixture, the dialkylphosphinate content of formula (I) is higher than 70%, preferably higher than 80%, more preferably higher than 90%.

In some embodiments, the flame retardant is aluminum diethylphosphinate 3 (C) ₄ H ₁₀ O ₂ P), al), or aluminum diethyl phosphinate 3 (C) ₄ H ₁₀ O ₂ P) Al and aluminum hypophosphite Al ₂ (HPO ₃ ) ₃ Or aluminium diethyl phosphinate 3 (C) ₄ H ₁₀ O ₂ P) a mixture of Al, melamine polyphosphate and zinc borate. When the halogen-free flame retardant is a mixture, aluminum diethylphosphinate 3 (C ₄ H ₁₀ O ₂ P) the Al content is higher than 70%, preferably higher than 80%, more preferably higher than 90%.

Preferably, component (C) is a glass fiber selected from a circular section glass fiber and/or a flat section glass fiber.

The flat section glass fiber refers to a glass fiber having a certain thickness-to-width ratio cross section, which may have various shapes including rectangular, elliptical, and approximately elliptical, with a profile ratio (ratio of short axis length to long axis length) ranging from 1:1.5 to 6, more preferably ranging from 1:2 to 5, and still more preferably ranging from 1:3 to 4.

Preferably, component (D) is a ceramic mineral selected from at least 60wt% of kyanite and a mixture of one or more selected from 0 to 40wt% of spherical alumina, titania and boron nitride; wherein:

the kyanite is a triclinic aluminosilicate-containing mineral with a chemical formula of A ₂ SiO ₅ Typical chemical composition is Al ₂ O ₃ 63.3% and SiO ₂ 36.7%. The term "triclinic system" is understood by those of ordinary skill in the art to mean a crystalline structure having neither a higher order axis of symmetry nor a secondary axis and plane of symmetry, three junctions of whichThe crystal axes are mutually inclined, the cell axes are equal to a @ b @ c, and the axis angles alpha @ beta @ gamma @ 90 ° (fig. 2). Triclinic kyanite is an unstable phase at high temperatures, has a low sintering temperature, and decomposes into mullite and fused silica glass when heated above 1100 ℃ by the reaction:

3(Al ₂ O ₃ ·SiO ₂ )→3Al ₂ O ₃ ·2SiO ₂ +SiO ₂

this transition helps to increase the load softening temperature and compressive strength and provides support strength to the article in the flame.

Preferably, component (E) is an epoxy resin, meaning that the molecule contains more than two epoxy groupsThe epoxy group may be located at the end of the molecular chain, in the middle or in a cyclic structure.

The epoxy resin is not particularly limited, and examples thereof include compounds having two or more glycidyl groups in one molecule. The epoxy resin to be used may be appropriately selected from those obtained by condensing epichlorohydrin with polyhydric phenols such as bisphenol or polyhydric alcohols under the action of an alkaline catalyst (usually sodium hydroxide).

In some embodiments, the epoxy resin is selected from one or more of bisphenol a type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin.

The epoxy resin preferably has an epoxy equivalent (eew) of 100 to 600g/eq. Eew of epoxy resin is the amount of resin containing one epoxy group (g/eq), i.e. the average molecular weight of the epoxy resin divided by the number of epoxy groups per molecule, eew of epoxy resin affects the curing agent addition ratio.

The bisphenol a type epoxy resin is not particularly limited, and epoxy resins useful for thermoplastic modification can be widely used. As a preferred example, D.E.R. manufactured by Olin Inc. of America is mentioned. ^TM 671, eew is 475-550g/eq.

The bisphenol F type epoxy resin is not particularly limited and can be widely usedThermoplastic modified epoxy resins. As a preferred example, D.E.R. manufactured by Olin Inc. of America is mentioned. ^TM 354, eew is 167-174g/eq.

The novolak type epoxy resin is not particularly limited, and epoxy resins useful for thermoplastic modification can be widely used. As a preferred example, for example, those produced by DIC corporation of JapanN-775, eew is 180-200g/eq.

Component (F) is a latent hardener which, as known to the skilled worker, has good storage stability at room temperature after being added to the epoxy resin and can rapidly react with the epoxy resin at high temperature, and finally forms a tough network-like three-dimensional polymer.

Preferably, the latent curing agent is Dicyandiamide (DICY) shown in a formula (III), or one or two mixtures of modified DICY compounds taking the formula (III) as a basic framework:

wherein DICY has a melting point of 208-211 ℃, and the molecular structure of DICY contains cyano (-CN) besides 4 active hydrogens, and the cyano can also be used as a functional group to participate in a curing reaction. DICY is a widely used latent heat-curable curing agent, and once it is heated to a temperature near the melting point, DICY starts to dissolve and starts to react with epoxy resin by heat. The dicyandiamide curing reaction temperature is generally 160-180 ℃ and the curing reaction time is 20-60 minutes. The dicyandiamide cured product has better mechanical property and heat resistance.

DICY is commercially available, and as a preferred example, DICY50 manufactured by Mitsubishi chemical corporation of Japan is used.

The modified DICY is a compound having DICY as a basic skeleton and exhibiting a curing acceleration effect, and includes a compound having a structure in which a part of hydrogen atoms included in amino groups of DICY is substituted, in addition to the DICY structure itself. The modified DICY derivative is commercially available, and as a preferred specific example, AH-154 is produced by Nippon Temminck.

Preferably, the amounts of DICY and modified DICY added are appropriately set in consideration of the epoxy equivalent of the epoxy resin. The ratio of the active hydrogen equivalent of the latent curing agent to the epoxy equivalent of the epoxy resin is preferably 0.05 to 0.25, more preferably 0.1 to 0.2.

The active hydrogen equivalent is the number of active hydrogen atoms contained in the molecule, and can be calculated according to formula (IV). Active hydrogen atoms refer to hydrogen atoms in the molecule that have a higher electron affinity. In the chemical reaction, active hydrogen atoms have strong electrophilicity and are easy to chemically react with other atoms or molecules.

Dicyandiamide has a molecular weight of 84 and a molecular structure with 4 active hydrogens, the active hydrogen equivalent weight being 21.

Preferably, the component (G) is other auxiliary agent selected from one or a mixture of two or more of colorant, mold release agent, heat stabilizer, flow improver and crystallization accelerator.

The invention also provides a preparation method of the fireproof and heat-resistant polyamide composition, which is obtained by heating, melting, blending and extruding through a single-screw or double-screw extruder.

Preferably, the single or twin screw extruder has an aspect ratio (L/D) of from 32 to 52, preferably an L/D of from 40 to 44.

Preferably, the processing temperature is set to 150-300℃and the screw speed is set to 200-500 rpm.

Preferably, the process of heating, melting, blending and extruding comprises the following steps:

feeding sequence: a side feeding port is arranged at the position of the rear section of the single-screw or double-screw extruder for heating and melting, a component (B) flame retardant, a component (C) glass fiber and a component (G) latent curing agent are added, and other material components are metered and added from a main feeding port of the extruder after being premixed;

and (3) exhausting: carrying out normal pressure exhaust on 1-2 charging barrel openings in front of a side feeding port of the extruder, and carrying out pressurizing exhaust on a second charging barrel opening at the last one of the die heads, wherein the pressure range is 30-70 cm-Hg;

the melt of the double-screw extruder is extruded through a die, cooled through a water tank, cut into particles by a granulator, and the collected particles are dried to a water content of below 0.1% and packaged.

The invention also provides application of the fireproof heat-resistant polyamide composition in preparing a lithium battery pack shell and a cover of a new energy automobile.

Compared with the prior art, the invention has the beneficial effects that:

the fireproof and heat-resistant polyamide composition is filled with the heat-conducting filler taking the tricyclopedia as the main body, the heat-conducting property is improved by a plurality of times to tens of times compared with the traditional high polymer material, the heat dissipation can be improved, and the thermal runaway of the battery can be reduced. In addition, the sintering temperature of triclinic minerals is low, which can provide support strength to the article in a flame. Secondly, a latent thermosetting system is introduced into the thermoplastic polymer, so that the plasticity characteristic is maintained, the dimensional stability of the component can be ensured under the working condition of the battery by curing, and the flame resistance of the combination is further improved. The flame-retardant and heat-resistant polyamide composition of the present invention was tested to withstand direct flame exposure at 1000 c for more than 15 minutes and provided sufficient time for the passengers to leave the vehicle in the event of thermal runaway.

Drawings

FIG. 1 is a schematic diagram of a sample flame exposure test in an example.

FIG. 2 is a schematic diagram of a crystal structure model of triclinic kyanite.

FIG. 3 is a photograph of the test piece of comparative example 1 after flame exposure for 1 minute.

FIG. 4 is a photograph of the test piece of example 1 after 15 minutes of flame exposure.

FIG. 5 shows the results of mechanical property tests after flame exposure of the test pieces of example 1 and comparative example 1.

Detailed Description

The invention is further illustrated by the following examples. It should be understood that the following examples are for illustrative purposes only and are not intended to limit the present invention.

The following materials were used in the examples and comparative examples:

PA 66: from polyamide 66 produced by Ningxia Ruitai Co.

PA 6: polyamide 6 from the company ruxi chemical.

PA610: from polyamide 610 manufactured by the company guangdong boundary.

PA612: from the company guangdong boundary, a polyamide 612.

PA46: from polyamide 46 produced by Dissman.

PA 56: from Kaiser company, polyamide 56.

PA 1010: from polyamide 1010 produced by the company guangdong boundary.

PA11: from polyamide 11 produced by Ai Mansi company.

PA 12: polyamide 12 from the company Wanhua.

MIX-PA: refers to PA610: PA612: PA46: PA 56: PA 1010: PA11: PA 12 was mixed by company Jin Lun in a ratio of 1:1:1:1:1:1 to 1 to obtain a mixture.

GF-1: round section glass fiber 995-10P, monofilament diameter 10 μm, manufactured by Shandong glass fiber Co.

GF-2: flat glass fiber ECS301 HP-3-M4 produced by Chongqing International composite material Co., ltd., the special-shaped ratio is 1:4.

FR-1: aluminum diethylphosphinate, trade name, from CraienOP1230。

FR-2: the mixture of aluminium diethylphosphinate, melamine polyphosphate and zinc borate from the company Clariant, the proportion of aluminium diethylphosphinate is about 70-80%, trade mark

FR-3: diethyl Ether from Craien CorpMixtures of aluminum phosphinate and aluminum hypophosphite, with proportions of aluminum diethylphosphinate of about 90%, brand

MIX-FR refers toThe mixture was obtained by mixing at a ratio of 1:1:1 by company Jin Lun.

Kyanite: kyanite from the united states kyanite mining industry, 100 mesh.

AL ₂ O ₃ : spherical alumina produced by Yishitong corporation.

TIO ₂ : the brand RCL-69 is a rutile titanium dioxide produced by the Australian Korst company.

BN: boron nitride, trade name CFA50M, from 3M company, usa.

MIX-MD: refers to spherical alumina: titanium dioxide RCL-69: boron nitride CFA50M was mixed at a ratio of 1:1:1 by company Jin Lun to obtain a mixture.

Epoxy-1: bisphenol a epoxy resin d.e.r from Olin company, usa. ^TM 671, epoxide equivalent 475 to 550g/eq.

Epoxy-2: bisphenol F epoxy resin d.e.r from Olin company, usa. ^TM 354, epoxy equivalent 167-174g/eq.

Epoxy-3 was obtained from DIC Japan as a novolak type Epoxy resinN-775, epoxy equivalent weight 180-200g/eq.

DICY-1: DICY50, active hydrogen equivalent 21g/eq, from Mitsubishi chemical corporation of Japan.

DICY-2: modified dicyandiamide compound AH-154, active hydrogen equivalent 17g/eq, produced by Nippon Weisu Co. .

1098: antioxidant 1098, available from basf corporation under the chemical name N, N' -bis- (3- (35-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine.

Black MB: PA6 carrier/40% carbon black masterbatch SC8715 from the boeing mill.

CaSt2: calcium stearate SAK-CS-P is produced by Sanyi, singapore.

Preparation method

The components were weighed out according to the compositions shown in Table 1 and then added to a twin-screw extruder for melt processing.

Extruder screw nominal diameter: 35mm.

Extruder screw aspect ratio: 40.

the processing temperature range is as follows: 150-300 ℃.

Host rotation speed range: 300rpm.

Feeding sequence: and a side feeding port is arranged at the position of the rear section of the extruder for heating and melting, the component (B) flame retardant, the component (C) reinforcing agent and the component (G) latent curing agent are added, and other material components are metered and added from a main feeding port of the extruder after premixing.

And (3) exhausting: and (3) carrying out normal-pressure exhaust on 1-2 charging barrel openings in front of a side feeding port of the extruder, and carrying out supercharging exhaust on the opening of the last charging barrel of the die head, wherein the pressure range is 30-70 cm-Hg.

Sample molding and conditioning

Sample molding and adjustment were performed according to the method prescribed in ISO 16396-2, with the molding melt temperature ranging from 250 to 300℃and the mold temperature ranging from 80 to 100 ℃; mechanical property test the test piece is placed in an environment of 23 ℃ and adjusted for more than 16 hours, and the water content of the test piece is ensured to be less than 0.2%; flammability test the test pieces were subjected to two preconditioning conditions of 23 ℃/50% rh/48 hours and 70 ℃/168 hours, respectively.

Thermal conductivity testing

The thermal conductivity is that of a material 1m thick under stable heat transfer conditions, the temperature difference between the two side surfaces is 1 degree (K, °C), and the heat transferred through 1 square meter area in 1 second is represented by the symbol lambda, and the unit is W/(m-K).

The thermal conductivity calculation formula λ=ρ×a×cp, wherein:

rho-material density is obtained by testing with an immersion method;

a-thermal diffusivity, obtained by testing with a laser flash method (Laser Flash Method);

cp-specific heat capacity was measured by DSC.

Flammability test

The V-stage vertical burning test was carried out according to the method prescribed in UL94, the test piece size was 125 mm. Times.13.0 mm. Times.1.5 mm, the flame height of the methane burner was 20mm, the inner flame height was 10mm, and the test instrument was an ATLAS HVUL2 burning box.

Flame exposure test

The flame height of the methane blast lamp is 125mm, the inner flame height is 40mm, the flame temperature is 1100 ℃, the blast lamp angle is 20+/-5 degrees, and the testing instrument is an ATLAS HVUL2 combustion box.

Test pieces of two sizes were provided for testing: the test piece dimensions for evaluating the appearance were 80mm×80mm×2mm, and the test piece dimensions for evaluating the mechanical properties were 80mm×10mm×4.0mm.

As shown in FIG. 1, the test piece is horizontally fixed during the test, the height is adjusted to enable the inner flame of the flame to contact the center position of the sample, and after the flame contacts and burns, if the test piece breaks or holes, the test is stopped and the time is recorded.

Mechanical property test

The bending performance is carried out according to the method specified in ISO178, the test piece size is 80mm multiplied by 10mm multiplied by 4mm, the pressing speed is 2mm/min, and the testing instrument is a ZWICK Z010 type universal testing machine.

High temperature exposure test

The test piece size is 80mm multiplied by 10mm multiplied by 4mm, the test piece is placed in an oven (closed environment), different environment temperatures are set, the temperature is raised to the set temperature, the temperature is kept for 10 minutes, then the test piece is taken out for appearance evaluation, and the test instrument is a Memmert UF110 oven.

Examples and comparative examples

Tables 1 and 2, figures 3-5 list the composition behavior of each example.

Comparative example 1 and comparative example 4 compare: the flame exposure performance of comparative example 4, after the addition of 20% kyanite, was significantly improved over comparative example 1, and the flame exposure was tolerated for 15 minutes to maintain structural integrity, indicating that the composition had improved fire performance due to kyanite addition, but both regimens failed the high temperature exposure test beyond the melting point of substrate PA66 (260 ℃).

Comparative example 1 compared with ratio 5: after 5% of epoxy resin and 0.2% of curing agent are added in comparative example 5, the flame-resistant exposure performance and the high-temperature exposure performance are improved, and the comparative example 5 can still keep the structural integrity in the environment temperature exceeding the melting point (260 ℃) of the base material PA66, which shows that the composition generates cross-linking curing due to the addition of the epoxy resin and the curing agent, and the fireproof performance and the high-temperature exposure performance of the composition are improved.

Comparative example 5, example 1 and example 3 compare: the proportion of kyanite in the 3 compositions was 0%, 20% and 50%, respectively, and it was observed that as the proportion of kyanite was increased, the flame resistance of the compositions was further improved. However, too high a proportion of kyanite will affect processability, and therefore, it is necessary to control the proportion of kyanite to a reasonable proportion.

Comparative example 7, comparative example 8 and comparative example 9 are compared with each other: the epoxy resin ratios in the 3 combinations were 3%, 5% and 10%, respectively, but no improvement in flame exposure and high temperature exposure properties of the composition was observed, indicating that the epoxy resin could not be cured to form a tough, network-like, three-dimensional polymer without the involvement of a curing agent.

Examples 5 to 10, epoxy resins of different proportions and different epoxy equivalent weights were selected, and the addition ratio of the curing agent was calculated according to the formula: curative ratio (%) = prednisone equivalent +.epoxy equivalent x 100. Experiments show that after the curing agent is added in a reasonable proportion, the epoxy resin in the composition can be cured smoothly, and therefore, the fireproof and heat-resistant properties of the composition are improved.

TABLE 1

Remarks: appearance evaluation O = structural integrity; delta=structure is significantly distorted; x = structural failure (burn-through or melting).

TABLE 2

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The foregoing is illustrative of a preferred embodiment of the present invention, but the present invention should not be limited to the disclosure of this embodiment. So that equivalents and modifications will fall within the scope of the invention, all within the spirit and scope of the invention as disclosed.

Claims

1. A flame retardant and heat resistant polyamide composition, characterized in that the flame retardant and heat resistant polyamide composition comprises the following components:

wherein the sum of the components accounts for 100 weight percent of the fireproof heat-resistant polyamide composition.

2. The flame-retardant and heat-resistant polyamide composition according to claim 1, wherein the aliphatic polyamide is a semi-crystalline polymer, the melting temperature is 150-300 ℃, the melting temperature is characterized by differential scanning calorimetry, and the heating and cooling rates are 10 ℃/min.

3. The flame-retardant and heat-resistant polyamide composition according to claim 1 or 2, wherein the repeating units of the aliphatic polyamide are selected from one or more monomers of aliphatic dicarboxylic acids, aliphatic diamines having not less than four carbon atoms, lactams; wherein:

and/or the aliphatic diamine having not less than four carbon atoms is selected from the group consisting of: butanediamine, pentanediamine, ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecyldiamine, tetradecanediamine, pentadecylenediamine, hexadecanediamine, heptadecylenediamine, octadecanediamine, nonadecylenediamine, icosanediamine, 2-methyl-1, 8-octanediamine, 2, 4-trimethylhexamethylenediamine, 2, 4-trimethylhexamethylenediamine;

and/or the lactam is selected from the group consisting of: epsilon-caprolactam, enantholactam, undecanolactam, dodecanolactam, alpha pyrrolidone, alpha piperidone.

4. A flame retardant and heat resistant polyamide composition according to claim 3 wherein said aliphatic polyamide and monomer are selected from one or more of the following tables.

5. The flame-retardant and heat-resistant polyamide composition according to any one of claims 1 to 4, wherein the aliphatic polyamide is PA66 and/or PA 6.

6. The flame retardant and heat resistant polyamide composition according to claim 1, wherein the flame retardant is a halogen-free flame retardant selected from dialkylphosphinates represented by formula (I); or a mixture of a dialkylphosphinate represented by the formula (I) and a phosphite represented by the formula (II); or a mixture of dialkylphosphinate salts, melamine polyphosphate salts and zinc borate represented by the formula (I);

in the formula (II), M ₂ Representation Mg, ca, al, sb, sn, ge, ti, zn, fe, zr, ce, bi, sr, mn, li, na, K; m represents an integer of 1 to 4;

when the halogen-free flame retardant is a mixture, the content of the dialkylphosphinate shown in the formula (I) is higher than 70 percent.

7. The flame retardant and heat resistant polyamide composition according to claim 6 wherein said flame retardant is aluminum diethylphosphinate, or a mixture of aluminum diethylphosphinate and aluminum hypophosphite, or a mixture of aluminum diethylphosphinate, melamine polyphosphate and zinc borate; when the flame retardant is a mixture, the content of aluminum diethylphosphinate is higher than 70%.

8. A flame-retardant and heat-resistant polyamide composition according to claim 1,

the glass fiber is selected from round section glass fiber and/or flat section glass fiber, the cross section of the flat section glass fiber is selected from one or more of rectangle, ellipse and near ellipse, and the special-shaped ratio is 1:1.5-6;

and/or the ceramic mineral is selected from at least 60wt% of kyanite, which is a triclinic aluminosilicate mineral with a chemical formula A, and one or more than two of spherical alumina, titanium dioxide and boron nitride in an amount of 0 to 40wt% ₂ SiO ₅ The chemical composition is Al ₂ O ₃ 63.3% and SiO ₂ 36.7％；

And/or the other auxiliary agent is selected from one or a mixture of more than two of a colorant, a release agent, a heat stabilizer, a flow improver and a crystallization accelerator.

9. The flame-retardant and heat-resistant polyamide composition according to claim 1, wherein the epoxy resin is one or more selected from the group consisting of bisphenol a type epoxy resin, bisphenol F type epoxy resin, and novolak type epoxy resin, and has an epoxy equivalent of 100 to 600g/eq.

10. The flame-retardant and heat-resistant polyamide composition according to claim 1, wherein the latent curing agent is dicyandiamide represented by formula (III), or a mixture of one or two of modified dicyandiamide compounds having formula (III) as a basic skeleton:

11. the flame-retardant and heat-resistant polyamide composition according to claim 10, wherein the ratio of the active hydrogen equivalent of the latent curing agent to the epoxy equivalent of the epoxy resin is 0.05 to 0.25:1.

12. the process for producing a flame-retardant and heat-resistant polyamide composition according to any one of claims 1 to 11, characterized in that it is obtained by extrusion by heating, melt blending in a single-screw or twin-screw extruder; wherein:

the length-diameter ratio L/D of the single screw extruder or the double screw extruder is 32-52;

the processing temperature is 150-300 ℃, and the screw rotating speed is 200-500 rpm.

13. The method of preparing a flame retardant and heat resistant polyamide composition according to claim 12, wherein said process of hot melt blending extrusion comprises:

feeding sequence: a side feeding port is arranged at the position of the rear section of the single-screw or double-screw extruder for heating and melting, a flame retardant and glass fiber are added, and other material components are metered and added from a main feeding port of the extruder after premixing;

14. Use of a fire-resistant and heat-resistant polyamide composition according to any one of claims 1 to 11 for the preparation of lithium battery casings and covers for new energy vehicles.