Halogen-free flame-retardant PBT composite material and preparation method thereof

Abstract

The invention belongs to the technical field of flame-retardant PBT composite materials, and relates to a halogen-free flame-retardant PBT composite material and a preparation method thereof, the halogen-free flame-retardant PBT composite material comprises the following components by mass: 80-85 parts of PBT, 5-8 parts of carbon fiber, 8-10 parts of a flame retardant, and 0.5-1 part of an antioxidant; the flame retardant is KH560-g-ADP-coated In2O3, and the preparation method comprises the following steps: firstly, dropwise adding an ADP suspension liquid into an indium oxide suspension liquid to obtain ADP-coated In2O3 composite powder; then dissolving the ADP (at) In2O3 composite powder in an ethanol-water mixed solution, and then dropwise adding KH560, so as to prepare KH560-g-ADP (at) In2O3; the preparation method comprises the following steps: uniformly mixing the PBT, the carbon fibers, the flame retardant and the antioxidant, conveying the mixture into a double-screw extruder, and carrying out melt extrusion granulation to obtain the halogen-free flame-retardant PBT composite material. The method provided by the invention solves the problem of poor compatibility of the flame retardant and the PBT matrix; and the product has good flame retardant property.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flame-retardant PBT composites, and relates to a halogen-free flame-retardant PBT composite and a preparation method thereof. BACKGROUND

[0002] PBT (polybutylene terephthalate) is an important thermoplastic saturated polyester, is one of the five major engineering plastics, and has excellent mechanical properties, chemical stability and processability, and is widely used in the fields of electronics and electrical appliances, automobiles, industry and the like; however, the oxygen index (LOI) of pure PBT is only about 21%, and PBT is a flammable material, which is accompanied by melt dripping and toxic smoke release during combustion, and thus needs to be modified by flame retardation to meet the safety requirements of application scenarios. For a long time, the most mainstream technology for imparting flame retardancy to PBT is a halogen flame retardant such as a bromine flame retardant. However, many bromine flame retardants have been confirmed to have persistence, bioaccumulation and toxicity, and they release toxic and corrosive smoke and dioxins during combustion, which poses a serious threat to the environment and human health. The most stringent environmental protection instructions worldwide have strictly limited or banned the use of many bromine flame retardants. Based on the above serious challenges of environment and safety, the market and technology drive have generated the demand for safer and more environmentally friendly alternative solutions, and halogen-free flame-retardant PBT composites have emerged as the times require.

[0003] At the current stage, environment-friendly flame retardants such as phosphorus flame retardants, nitrogen flame retardants and inorganic hydroxides gradually replace halogen flame retardants and become the mainstream of the market. However, many new problems have emerged. Most halogen-free flame retardants are non-polar, hydrophilic inorganic or small molecular crystals. PBT resin is a hydrophobic, non-polar organic polymer, and the two are incompatible at the molecular level, resulting in very weak interfacial bonding force between the flame retardant particles and the PBT matrix. Compared with the traditional bromine-antimony system, the flame-retardant efficiency of most halogen-free flame retardants is relatively low, and thus a larger amount is required to meet the requirements of flame retardation. A large number of rigid and hard flame retardant particles are dispersed in the PBT matrix, and the tensile strength and tensile elongation of the material will decrease sharply, showing brittle fracture, and the product is prone to cracking under stress and installation.

[0004] For example, patent CN110041674A discloses a halogen-free flame-retardant PBT / HDPE composite, which adds ADP to improve the flame-retardant performance of the PBT / HDPE composite. However, ADP has a large compatibility problem with the PBT matrix, and the flame retardant is prone to uneven distribution, migration and precipitation between the matrix.

[0005] In order to solve the above problems, the patent CN118515958A adopts ethylenediaminetetraacetic acid to organically modify ADP with cyclodextrin, and the modified flame retardant has good compatibility with the matrix, but the synergistic effect of each component of the modified flame retardant is weak, and a high addition amount (15-20 wt% of the matrix) is required to achieve good flame retardant effect, which greatly affects the mechanical properties of the matrix.

[0006] Therefore, it is of great significance to study a halogen-free flame-retardant PBT composite material and a preparation method thereof to solve the problem that the flame-retardant performance and mechanical properties of the flame-retardant PBT composite material in the prior art cannot be considered. SUMMARY

[0007] The purpose of the present application is to solve the problems in the prior art and provide a halogen-free flame-retardant PBT composite material and a preparation method thereof.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0009] A halogen-free flame-retardant PBT composite material comprises the following components in mass fraction:

[0010]

[0011] The flame retardant is KH560-g-ADP@In2O3, and the preparation method is as follows: first, the ADP suspension is added to the indium oxide suspension at a rate of 1±0.2mL min -1 pH 3.8±0.2, and then stirred, centrifuged, washed and vacuum dried to obtain ADP@In2O3 composite powder; then the ADP@In2O3 composite powder is dissolved in an ethanol-water mixture, and then KH560 is added at a rate of 1±0.2mL min -1 If the KH560 is poured or added at a too fast rate, a large amount of KH560 will easily condense into silicone oil microspheres), and then filtered, washed and dried to obtain KH560-g-ADP@In2O3.

[0012] As a preferred technical scheme:

[0013] The halogen-free flame-retardant PBT composite material as described above, the melting point of PBT is 225±5℃, and the melt index under the condition of 250℃ and 2.16kg is 25±5g / 10min.

[0014] The halogen-free flame-retardant PBT composite material as described above, the specific preparation steps of KH560-g-ADP@In2O3 are as follows:

[0015] (1) Indium oxide powder was ultrasonically dispersed in deionized water to obtain an indium oxide suspension with a concentration of 1±0.2wt%, and the pH was adjusted to 3.8±0.2;

[0016] (2) ADP (aluminum diethylphosphonate) was ultrasonically dispersed in deionized water to obtain an ADP suspension with a concentration of 2.5 ± 0.3 wt%.

[0017] (3) The ADP suspension was diluted with 1 ± 0.2 mL / min. -1 The solution was added dropwise to the indium oxide suspension at a certain rate. After stirring, centrifugation, washing, and vacuum drying, ADP@In2O3 composite powder with In2O3 core and ADP shell was obtained.

[0018] (4) Dissolve the ADP@In2O3 composite powder in an ethanol-water mixture, and then add 1±0.2 mL min to it. -1 KH560 was added dropwise at a certain rate, and after stirring, the mixture was filtered, washed, and dried to obtain KH560-g-ADP@In2O3.

[0019] As described above, in step (1), a halogen-free flame-retardant PBT composite material with a concentration of 0.1 ± 0.02 mol / L is used. -1 Dilute hydrochloric acid is used to adjust the pH.

[0020] In the halogen-free flame-retardant PBT composite material described above, the stirring rate in step (3) is 500±50 rpm and the stirring time is 60±10 min; the centrifugation speed is 10000±500 rpm and the centrifugation time is 15±3 min; washing refers to washing twice with deionized water; the vacuum drying temperature is 70±5℃ and the time is 12±2 h.

[0021] In the halogen-free flame-retardant PBT composite material described above, the mass ratio of ADP@In2O3, KH560 and ethanol-water mixture in step (4) is 1:0.2±0.02:20±2; and the volume ratio of ethanol to water in the ethanol-water mixture is 8.5±0.5:1.

[0022] In the halogen-free flame-retardant PBT composite material described above, the stirring rate in step (4) is 300±30 rpm and the stirring time is 3±0.5 h; washing refers to washing with deionized water 3 times; the drying temperature is 80±10℃ and the drying time is 12±2 h.

[0023] The halogen-free flame-retardant PBT composite material described above has an LOI > 33%, a flame retardant rating of V0, and a tensile strength > 120 MPa.

[0024] The preparation method of the halogen-free flame-retardant PBT composite material as claimed in any one of the above, wherein the PBT, carbon fibers, flame retardant and antioxidant are uniformly mixed and then fed into a double-screw extruder for melt extrusion and granulation to obtain the halogen-free flame-retardant PBT composite material.

[0025] As a preferred technical solution,

[0026] The method as described above, wherein the temperature of each section of the double-screw extruder is 230±10℃, 240±10℃, 245±10℃, 245±10℃, 245±10℃, 240±10℃ respectively, the screw temperature is 300±15℃, and the screw rotation speed is 320-360r / min.

[0027] Principle of the application:

[0028] When the pH is controlled at 3.8±0.2, the surface of indium oxide dispersed in water is positively charged (this pH is far lower than the isoelectric point thereof), and the surface of ADP particles dispersed in water is negatively charged (because the surface of ADP crystal is rich in diethyl phosphinic acid root ions). When the ADP suspension and the indium oxide suspension are mixed, the indium oxide with strong positive charge is immediately adsorbed to the surface of the ADP particles with negative charge to obtain ADP@In2O3 composite particles; however, the composite particles obtained by electrostatic adsorption are not stable, and there is still a large compatibility problem between the composite particles and PBT during melt extrusion and granulation. By adding KH560 dropwise in the system of ADP@In2O3 composite particles, the silanol generated by the hydrolysis of KH560 can condense with the surface hydroxyl groups of the composite particles, and the adjacent silanols can also self-condense to form stable Si-O-Si bonds (which can protect the internal electrostatic bond from thermal decomposition), thereby forming a complete KH560-g-ADP@In2O3 three-layer core-shell structure with excellent thermal stability. The epoxy groups in KH560 can be secondarily crosslinked with the carboxyl groups in PBT during thermal processing, and the PBT matrix has good compatibility and can inhibit melt dripping.

[0029] The strong protonic acids such as phosphoric acid derivatives and polyphosphoric acid generated by the thermal decomposition of ADP at high temperature can attack the ester groups (-CO-O-) on the PBT chain to cause acid-catalyzed alcoholysis / hydrolysis, and the PBT chain is broken into oligomer fragments containing carboxyl groups (-COOH) and hydroxyl groups (-OH). + Under catalysis, the β-elimination reaction occurs to generate a double bond and further crack to form a carbon layer; the indium oxide exhibits strong Lewis acidity under the high-temperature combustion condition, and the In 3+ sites on the surface can act as electron pair acceptors to coordinate with the oxygen atoms in the ester groups (-CO-O-) and carbonyl groups (C=O) on the PBT molecular chain to form a complex, which polarizes and weakens the original chemical bonds in the PBT molecular chain, making it more prone to breakage and rearrangement. 3+The O lone pair electrons of the phosphorus-containing species of the ·PO / ·PO2 and Al-PO4 fragments released by the decomposition of ADP can be coordinated to form an In-O-P transition state, increase the polarity of the P=O bond, and significantly enhance the efficiency of P radicals in capturing H· and OH· radicals in the combustion chain reaction, both of which act on the PBT chain to achieve more efficient and more complete dehydration, dehydrogenation and crosslinking to carbon, thereby greatly improving the flame retardant performance.

[0030] Advantages:

[0031] (1) The preparation method of the halogen-free flame-retardant PBT composite material solves the problem of poor compatibility with the PBT matrix by adding KH560 in the ADP@In2O3 composite particle system, and finally obtains a halogen-free flame-retardant PBT composite material with excellent mechanical properties.

[0032] (2) The halogen-free flame-retardant PBT composite material has a flame retardant KH560-g-ADP@In2O3 with a three-layer core-shell structure in the PBT composite material, which has excellent thermal stability and good flame retardant performance. DETAILED DESCRIPTION

[0033] The application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not to limit the scope of the application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content taught by the application, and these equivalent forms also fall within the scope of the claims attached to the present application.

[0034] The test methods involved in the performance indicators in the examples and comparative examples of the application are as follows:

[0035] LOI performance: tested according to GB / T 2406.2-2009.

[0036] Vertical burning performance: tested according to condition A of GB / T 2408-2021.

[0037] Tensile strength: tested according to GB / T 1040.2-2022.

[0038] Example 1

[0039] A preparation method of a halogen-free flame-retardant PBT composite material, the specific steps are as follows:

[0040] (1) Ultrasonic dispersion of indium oxide powder in deionized water to obtain a 1wt% indium oxide suspension, and adjust the pH to 3.7 with 0.1mol / L dilute hydrochloric acid; -1

[0041] ​(2) ultrasonic dispersion of ADP in deionized water to obtain ADP suspension with a concentration of 2.5wt%;

[0042] (3) dropwise addition of the ADP suspension to the In2O3 suspension after pH adjustment in step (1) at a rate of 1mL min -1 , stirring, centrifugation, washing in sequence, and vacuum drying to obtain ADP@In2O3 composite powder with a core layer of In2O3 and a shell layer of ADP;

[0043] wherein the stirring rate is 500rpm, the stirring time is 60min; the centrifugal speed is 9800rpm, the centrifugal time is 13min; the washing refers to deionized water washing for 2 times; the vacuum drying temperature is 70℃, and the time is 12h;

[0044] (4) dissolution of the ADP@In2O3 composite powder in an ethanol-water mixture with a volume ratio of 9:1, dropwise addition of KH560 to the mixture at a rate of 0.8mL min -1 , stirring, filtration, deionized water washing for 3 times, and drying to obtain KH560-g-ADP@In2O3, i.e. a flame retardant;

[0045] wherein the mass ratio of the ADP@In2O3 composite powder, KH560, and the ethanol-water mixture is 1:0.2:20; the stirring rate is 330rpm, and the stirring time is 3h; the drying temperature is 80℃, and the drying time is 12h;

[0046] (5) mixing of 85 parts of PBT (manufacturer: Changchun Chemical (Jiangsu), brand: PBT 1100-211M), 7 parts of carbon fiber (manufacturer: Shanghai Diping High Polymer, brand: CT70-006EP), 8 parts of the flame retardant, and 0.7 parts of antioxidant 168 (manufacturer: BASF, brand: 168) in a mass ratio, and then conveying to a twin-screw extruder for melt extrusion and granulation to obtain a halogen-free flame-retardant PBT composite material;

[0047] The temperature of each section of the twin-screw extruder is 230℃, 240℃, 245℃, 245℃, 245℃, 240℃, the screw temperature is 300℃, and the screw rotation speed is 320r / min.

[0048] The halogen-free flame-retardant PBT composite material obtained finally has an LOI of 34%, a flame-retardant grade of V0, and a tensile strength of 129MPa.

[0049] Comparative Example 1

[0050] ​A preparation method of a halogen-free flame-retardant PBT composite material, which is basically the same as that in Embodiment 1, except that the pH is not adjusted with dilute hydrochloric acid after the indium oxide suspension is prepared in step (1) and is directly used in step (3).

[0051] The LOI of the finally prepared halogen-free flame-retardant PBT composite material is 26%, and the flame-retardant grade is V1.

[0052] Comparing Comparative Example 1 with Embodiment 1, it can be found that the flame-retardant effect is obviously decreased, because when the pH is not adjusted, the pH in the system is about 6-7, which is higher than the isoelectric point of indium oxide, and the indium oxide cannot be electrostatically combined with ADP, and after being modified with KH560, In2O3@KH560 and ADP@KH560 are formed, and the synergistic effect of the two is greatly decreased, thereby affecting the flame-retardant effect.

[0053] Comparative Example 2

[0054] A preparation method of a halogen-free flame-retardant PBT composite material, which is basically the same as that in Embodiment 1, except that the pH is adjusted to 3.5 with dilute hydrochloric acid in step (1).

[0055] The LOI of the finally prepared halogen-free flame-retardant PBT composite material is 27%, the flame-retardant grade is V1, and the tensile strength is 90 MPa.

[0056] Comparing Comparative Example 2 with Embodiment 1, it can be found that both the flame-retardant effect and the mechanical properties are decreased, because if the pH is too low, although it is lower than the isoelectric point of indium oxide, it is beneficial to electrostatic combination, but it promotes the hydrolysis of ADP and reduces the grafting ability of KH560, thereby causing the flame-retardant effect of the flame retardant and the compatibility of the flame retardant with the matrix to be decreased.

[0057] Comparative Example 3

[0058] A preparation method of a halogen-free flame-retardant PBT composite material, which is basically the same as that in Embodiment 1, except that the operation in step (4) is omitted, that is, the flame retardant is ADP@In2O3.

[0059] The LOI of the finally prepared halogen-free flame-retardant PBT composite material is 28%, the flame-retardant grade is V2, and the tensile strength is 77 MPa.

[0060] Comparing Comparative Example 3 with Embodiment 1, it can be found that both the flame-retardant effect and the mechanical properties of the composite material are decreased, because the compatibility of the composite particles modified without coupling agent KH560 with the matrix is poor, the flame-retardant components are easy to migrate and precipitate, and there are many stress concentration points, so the material is more prone to fracture under stress.

[0061] Embodiment 2

[0062] A preparation method of a halogen-free flame-retardant PBT composite material, the specific steps of which are as follows:

[0063] (1) Indium oxide powder was ultrasonically dispersed in deionized water to obtain an indium oxide suspension with a concentration of 0.8 wt%, and then diluted with a solution containing 0.12 mol / L. -1 Adjust the pH to 3.6 with dilute hydrochloric acid;

[0064] (2) ADP was ultrasonically dispersed in deionized water to obtain an ADP suspension with a concentration of 2.7 wt%.

[0065] (3) Add the ADP suspension at 1.2 mL / min -1 The solution was added dropwise to the indium oxide suspension after pH adjustment in step (1), and after stirring, centrifugation, and washing, it was vacuum dried to obtain ADP@In2O3 composite powder with In2O3 core and ADP shell.

[0066] The stirring rate was 520 rpm, and the stirring time was 70 min; the centrifugation speed was 10500 rpm, and the centrifugation time was 18 min; washing involved washing twice with deionized water; and the vacuum drying temperature was 72℃, and the time was 13 h.

[0067] (4) Dissolve the ADP@In2O3 composite powder in an ethanol-water mixture with a volume ratio of 8.8:1, and then add 1 mL of the mixture to the solution. -1 KH560 was added dropwise at a certain rate, stirred, filtered, washed three times with deionized water, and dried to obtain KH560-g-ADP@In2O3, which is a flame retardant.

[0068] The mass ratio of ADP@In2O3 composite powder, KH560 and ethanol-water mixture was 1:0.2:20; the stirring speed was 300 rpm and the stirring time was 2.8 h; the drying temperature was 90 ℃ and the drying time was 12 h.

[0069] (5) By weight, mix 80 parts PBT (manufacturer: Changchun Chemical (Jiangsu), grade: PBT 1100-211M), 8 parts carbon fiber (manufacturer: Shanghai Dipeng Polymer, grade: CT70-006EP), 10 parts flame retardant and 1 part antioxidant 168 (manufacturer: BASF, grade: ...). 168) After being mixed evenly, the mixture is fed into a twin-screw extruder and melt-extruded to granulate, thus obtaining a halogen-free flame-retardant PBT composite material;

[0070] The temperatures of each section of the twin-screw extruder are 220℃, 230℃, 235℃, 236℃, 236℃, and 230℃, respectively, the screw temperature is 285℃, and the screw speed is 330 r / min.

[0071] The final halogen-free flame-retardant PBT composite material had an LOI of 35%, a flame retardancy rating of V0, and a tensile strength of 136 MPa.

[0072] Example 3

[0073] A method for preparing a halogen-free flame-retardant PBT composite material, the specific steps of which are as follows:

[0074] (1) Indium oxide powder was ultrasonically dispersed in deionized water to obtain an indium oxide suspension with a concentration of 0.9 wt%, and then diluted with a 0.1 mol / L solution. -1 Adjust the pH to 3.7 with dilute hydrochloric acid;

[0075] (2) ADP was ultrasonically dispersed in deionized water to obtain an ADP suspension with a concentration of 2.8 wt%;

[0076] (3) Add the ADP suspension at 0.8 mL / min -1 The solution was added dropwise to the indium oxide suspension after pH adjustment in step (1), and after stirring, centrifugation, and washing, it was vacuum dried to obtain ADP@In2O3 composite powder with In2O3 core and ADP shell.

[0077] The stirring rate was 550 rpm for 70 min; the centrifugation speed was 9500 rpm for 15 min; washing involved washing twice with deionized water; and vacuum drying was carried out at 75℃ for 10 h.

[0078] (4) Dissolve the ADP@In2O3 composite powder in an ethanol-water mixture with a volume ratio of 8.0:1, and then add 1.1 mL of the solution to the mixture. -1 KH560 was added dropwise at a certain rate, stirred, filtered, washed three times with deionized water, and dried to obtain KH560-g-ADP@In2O3, which is a flame retardant.

[0079] The mass ratio of ADP@In2O3 composite powder, KH560 and ethanol-water mixture was 1:0.18:18; the stirring speed was 300 rpm and the stirring time was 3.3 h; the drying temperature was 85 ℃ and the drying time was 14 h.

[0080] (5) By weight, 81 parts PBT (manufacturer: Changchun Chemical (Jiangsu), grade: PBT 1100-211M), 5 parts carbon fiber (manufacturer: Shanghai Dipeng Polymer, grade: CT70-006EP), 10 parts flame retardant and 0.5 parts antioxidant 168 (manufacturer: BASF, grade: ...). 168) After being mixed evenly, the mixture is fed into a twin-screw extruder and melt-extruded to granulate, thus obtaining a halogen-free flame-retardant PBT composite material;

[0081] The temperature of each section of the twin-screw extruder was 225℃, 235℃, 240℃, 240℃, 240℃, and 235℃, respectively, the screw temperature was 290℃, and the screw rotation speed was 340r / min.

[0082] The LOI of the prepared halogen-free flame-retardant PBT composite material was 36%, the flame-retardant grade was V0, and the tensile strength was 123MPa.

[0083] Example 4

[0084] A preparation method of a halogen-free flame-retardant PBT composite material, the specific steps are as follows:

[0085] (1) ultrasonic dispersion of indium oxide powder in deionized water to obtain an indium oxide suspension with a concentration of 1.2wt%, and adjustment of pH to 3.8 with dilute hydrochloric acid with a concentration of 0.08mol / L; -1

[0086] (2) ultrasonic dispersion of ADP in deionized water to obtain an ADP suspension with a concentration of 2.2wt%;

[0087] (3) dropwise addition of the ADP suspension to the pH-adjusted indium oxide suspension in step (1) at a rate of 1mL / min -1 , stirring, centrifugation, and washing in sequence, and vacuum drying to obtain ADP@In2O3 composite powder with a core layer of In2O3 and a shell layer of ADP;

[0088] wherein the stirring rate was 450rpm and the stirring time was 50min; the centrifugation speed was 10200rpm and the centrifugation time was 12min; the washing was deionized water washing for 2 times; the vacuum drying temperature was 65℃ and the time was 14h;

[0089] (4) dissolution of the ADP@In2O3 composite powder in an ethanol-water mixture with a volume ratio of 8.3:1, dropwise addition of KH560 at a rate of 0.8mL / min -1 , stirring, and then filtration, deionized water washing for 3 times, and drying in sequence to obtain KH560-g-ADP@In2O3, i.e., a flame retardant;

[0090] wherein the mass ratio of the ADP@In2O3 composite powder, KH560, and the ethanol-water mixture was 1:0.18:22; the stirring rate was 290rpm and the stirring time was 2.5h; the drying temperature was 70℃ and the drying time was 11h;

[0091] ​(5) 80 parts of PBT (manufacturer: Changchun Chemical Industry (Jiangsu), brand: PBT 1100-211M), 5 parts of carbon fiber (manufacturer: Shanghai Diping High Polymer, brand: CT70-006EP), 8 parts of flame retardant, and 0.8 parts of antioxidant 168 (manufacturer: BASF, brand: After being uniformly mixed, the mixture is conveyed into a twin-screw extruder, melt-extruded and granulated to obtain a halogen-free flame-retardant PBT composite material;

[0092] The temperature of each section of the twin-screw extruder is 230℃, 240℃, 245℃, 245℃, 245℃, 240℃, the screw temperature is 300℃, and the screw rotation speed is 350 r / min.

[0093] The halogen-free flame-retardant PBT composite material finally obtained has an LOI of 34%, a flame-retardant grade of V0, and a tensile strength of 124 MPa.

[0094] Example 5

[0095] A method for preparing a halogen-free flame-retardant PBT composite material, the specific steps being as follows:

[0096] (1) Ultrasonic dispersion of indium oxide powder in deionized water to obtain an indium oxide suspension with a concentration of 1wt%, and adjustment of pH to 4 with dilute hydrochloric acid with a concentration of 0.09mol / L; -1

[0097] (2) Ultrasonic dispersion of ADP in deionized water to obtain an ADP suspension with a concentration of 2.5wt%;

[0098] (3) Dropwise addition of the ADP suspension to the indium oxide suspension after adjustment of pH in step (1) at a rate of 0.8mL / min -1 , followed by stirring, centrifugation, washing, and vacuum drying to obtain ADP@In2O3 composite powder with a core layer of In2O3 and a shell layer of ADP;

[0099] wherein the stirring rate is 480 rpm, the stirring time is 55 min, the centrifugation speed is 10000 rpm, the centrifugation time is 15 min, the washing refers to washing twice with deionized water, and the vacuum drying temperature is 68℃ and the time is 12h;

[0100] (4) Dissolution of the ADP@In2O3 composite powder in an ethanol-water mixture with a volume ratio of 8.5:1, dropwise addition of KH560 at a rate of 1.2mL / min -1 , followed by stirring, filtration, washing with deionized water for 3 times, and drying to obtain KH560-g-ADP@In2O3, i.e., a flame retardant;

[0101] ​The mass ratio of the ADP@In2O3 composite powder, KH560 and the ethanol-water mixed solution is 1:0.22:18; the stirring rate is 270 rpm, and the stirring time is 3 h; the drying temperature is 75 ℃, and the drying time is 10 h;

[0102] (5) 85 parts of PBT (manufacturer: Changchun Chemical Industry (Jiangsu), brand: PBT 1100-211M), 8 parts of carbon fiber (manufacturer: Shanghai Diping High Polymer, brand: CT70-006EP), 9 parts of flame retardant and 1 part of antioxidant 168 (manufacturer: BASF, brand: 168) are uniformly mixed and then conveyed into a double-screw extruder to be melt-extruded and granulated to obtain a halogen-free flame-retardant PBT composite material;

[0103] The temperature of each section of the double-screw extruder is 235 ℃, 245 ℃, 250 ℃, 250 ℃, 250 ℃, 245 ℃, respectively, the screw temperature is 310 ℃, and the screw rotation speed is 360 r / min.

[0104] The LOI of the finally obtained halogen-free flame-retardant PBT composite material is 34%, the flame-retardant grade is V0, and the tensile strength is 134 MPa.

[0105] Example 6

[0106] A preparation method of a halogen-free flame-retardant PBT composite material, and the specific steps are as follows:

[0107] (1) Indium oxide powder is ultrasonically dispersed in deionized water to obtain an indium oxide suspension with a concentration of 0.8 wt%, and the pH is adjusted to 3.8 with dilute hydrochloric acid with a concentration of 0.12 mol / L; -1

[0108] (2) ADP is ultrasonically dispersed in deionized water to obtain an ADP suspension with a concentration of 2.3 wt%;

[0109] (3) The ADP suspension is added to the pH-adjusted indium oxide suspension of step (1) at a rate of 1.1 mL / min -1 , and after stirring, centrifugation and washing in sequence, ADP@In2O3 composite powder with a core layer of In2O3 and a shell layer of ADP is obtained by vacuum drying;

[0110] The stirring rate is 550 rpm, and the stirring time is 65 min; the centrifugal speed is 10,000 rpm, and the centrifugal time is 17 min; the washing refers to washing with deionized water for 2 times; the vacuum drying temperature is 70 ℃, and the time is 10 h;

[0111] (4) The ADP@In2O3 composite powder is dissolved in an ethanol-water mixed solution with a volume ratio of 8.5:1, and then 1 mL / min​-1 The rate of adding KH560, stirring, and then filtering, washing with deionized water 3 times, drying, to obtain KH560-g-ADP@In2O3, namely the flame retardant;

[0112] The mass ratio of ADP@In2O3 composite powder, KH560 and ethanol-water mixed solution is 1:0.18:22; the stirring rate is 320 rpm, the stirring time is 3.5 h; the drying temperature is 80℃, and the drying time is 12 h;

[0113] (5) 83 parts of PBT (manufacturer: Changchun Chemical Industry (Jiangsu), brand: PBT 1100-211M), 6 parts of carbon fiber (manufacturer: Shanghai Diping High Polymer, brand: CT70-006EP), 9 parts of flame retardant and 0.7 parts of antioxidant 168 (manufacturer: BASF, brand: Irganox® 168) are mixed uniformly and then conveyed into a twin-screw extruder for melt extrusion and granulation to obtain halogen-free flame-retardant PBT composite material;

[0114] The temperature of each section of the twin-screw extruder is 240℃, 250℃, 255℃, 255℃, 255℃, 250℃, respectively, the screw temperature is 315℃, and the screw rotation speed is 320 r / min.

[0115] The LOI of the finally obtained halogen-free flame-retardant PBT composite material is 34%, the flame-retardant grade is V0, and the tensile strength is 127 MPa.​

Claims

1. A halogen-free flame-retardant PBT composite material, characterized in that The components include the following parts by mass: The flame retardant is KH560-g-ADP@In2O3, and a preparation method thereof is as follows: first, ADP suspension is added to indium oxide suspension with a pH of 3.8±0.2 at a rate of 1±0.2 mL / min, and after stirring, centrifugation and washing in sequence, ADP@In2O3 composite powder is obtained by vacuum drying; then, the ADP@In2O3 composite powder is dissolved in an ethanol-water mixture, and KH560 is added thereto at a rate of 1±0.2 mL / min, and after stirring, filtration, washing and drying in sequence, KH560-g-ADP@In2O3 is prepared. -1 -1 ​​ 2. The halogen-free flame-retardant PBT composite material according to claim 1, characterized in that, The melting point of PBT is 225±5℃, and the melt index at 250℃ and 2.16kg is 25±5g / 10min.

3. The halogen-free flame-retardant PBT composite material according to claim 1, characterized in that, The specific preparation steps of KH560-g-ADP@In2O3 are as follows: (1) Indium oxide powder was ultrasonically dispersed in deionized water to obtain an indium oxide suspension with a concentration of 1±0.2wt%, and the pH was adjusted to 3.8±0.2; (2) ADP was ultrasonically dispersed in deionized water to obtain an ADP suspension with a concentration of 2.5 ± 0.3 wt%. (3) The ADP suspension is added to the indium oxide suspension at a rate of 1±0.2 mL min -1 After stirring, centrifugation, and washing in sequence, the ADP@In2O3 composite powder is obtained by vacuum drying. (4) The ADP@In2O3 composite powder is dissolved in an ethanol-water mixture, and then KH560 is added dropwise at a rate of 1±0.2 mL / min -1 , and after stirring, the KH560-g-ADP@In2O3 is obtained after filtration, washing, and drying in sequence.

4. The halogen-free flame-retardant PBT composite material according to claim 3, characterized in that, In step (1) the pH is adjusted with dilute hydrochloric acid of concentration 0.1 ± 0.02 mol L -1 -1.

5. The halogen-free flame-retardant PBT composite material according to claim 3, characterized in that, In step (3), the stirring rate is 500±50 rpm and the stirring time is 60±10 min; the centrifugation speed is 10000±500 rpm and the centrifugation time is 15±3 min; washing refers to washing twice with deionized water; the vacuum drying temperature is 70±5℃ and the time is 12±2 h.

6. The halogen-free flame-retardant PBT composite material according to claim 3, characterized in that, In step (4), the mass ratio of ADP@In2O3, KH560 and ethanol-water mixture is 1:0.2±0.02:20±2; in the ethanol-water mixture, the volume ratio of ethanol to water is 8.5±0.5:

1.

7. The halogen-free flame-retardant PBT composite material according to claim 3, characterized in that, In step (4), the stirring rate is 300±30 rpm and the stirring time is 3±0.5 h; washing refers to washing three times with deionized water; the drying temperature is 80°C. The drying temperature is ±10℃, and the drying time is 12±2h.

8. A halogen-free flame-retardant PBT composite material according to any one of claims 1 to 7, characterized in that, The halogen-free flame-retardant PBT composite material has an LOI > 33%, a flame retardant rating of V0, and a tensile strength > 120 MPa.

9. A method for preparing a halogen-free flame-retardant PBT composite material according to any one of claims 1 to 8, characterized in that: PBT, carbon fiber, flame retardant and antioxidant are mixed evenly and then fed into a twin-screw extruder for melt extrusion granulation to obtain halogen-free flame-retardant PBT composite material.

10. The method according to claim 9, characterized in that, The temperatures of each section of the twin-screw extruder are 230±10℃, 240±10℃, 245±10℃, 245±10℃, 245±10℃, and 240±10℃, respectively. The screw temperature is 300±15℃, and the screw speed is 320~360r / min.

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