CN113265104B - Polypropylene composite material and preparation method thereof - Google Patents

Abstract

The invention provides a polypropylene composite material, which comprises the following raw materials: polypropylene resin, glass fiber, modified cyclodextrin, composite antibacterial agent and polyethylene polyoctene elastomer. The polypropylene composite material has good flame retardant property and antibacterial property. The invention takes biomass cyclodextrin and intumescent flame retardant as raw materials to prepare the novel hydrophobic cyclodextrin-based halogen-free intumescent flame retardant, and improves the compatibility and the dispersibility between the novel hydrophobic cyclodextrin-based halogen-free intumescent flame retardant and a matrix material.

Description

Polypropylene composite material and preparation method thereof

technical field

The invention relates to the technical field of polymer composite materials, in particular to a polypropylene composite material.

Background technique

Polypropylene material is a non-toxic, odorless and lightweight material with good dielectric properties and high-frequency insulation, suitable for making general mechanical parts, corrosion-resistant parts, insulating parts and tableware. However, polypropylene is flammable, and a composite material made of glass fiber is more flammable due to the "wick effect" of glass fiber. Therefore, it is very important to improve the flame retardant properties of polypropylene composites. In addition, in some application fields, such as indoor household products, etc., composite materials are required to have certain antibacterial and antiviral properties, so that they can be kept clean and sterile for a long time in use and avoid the breeding of harmful microorganisms.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies in the prior art, the present invention provides a polypropylene composite material.

The technical scheme adopted in the present invention is:

Polypropylene composite material, consisting of the following raw materials: polypropylene resin, glass fiber, modified cyclodextrin and polyethylene polyoctene elastomer.

Preferably, the polypropylene composite material is composed of the following raw materials: 18-23wt% glass fiber, 15-24wt% modified cyclodextrin, 3-7wt% polyethylene polyoctene elastomer, and the balance is polypropylene resin.

Further, the polypropylene composite material is composed of the following raw materials: polypropylene resin, glass fiber, modified cyclodextrin, composite antibacterial agent and polyethylene polyoctene elastomer.

Preferably, the polypropylene composite material is composed of the following raw materials: 18-23wt% glass fiber, 15-24wt% modified cyclodextrin, 2-6wt% composite antibacterial agent, 3-7wt% polyethylene polyoctene elastomer, The balance is polypropylene resin.

The composite antibacterial agent is prepared by the following method: 0.5-1 parts by weight of polyaminopropyl biguanide and 1-1.5 parts by weight of benzyl dimethyl dodecyl ammonium bromide are added to 95-100 parts by weight of water and ultrasonicated Treat for 3-6min, ultrasonic frequency 20-30kHz, ultrasonic power 300-500W; then add 0.5-1.5 parts by weight of heparin sodium salt, 0.5-1.5 parts by weight of sodium palmitate and stir for 10-20min, stirring speed 100-150rpm; reduce pressure Concentrated and freeze-dried to obtain a composite antibacterial agent.

Cyclodextrin is a common biomass-based material, mainly derived from starch, and its molecular structure contains many hydroxyl groups. Under inert atmosphere, cyclodextrin can be degraded to generate some carbon residues with better thermal stability. Due to its special carbonization ability, cyclodextrin has become a substitute for traditional carbon sources in intumescent flame retardant systems. The direct blending of cyclodextrin and polymer materials will lead to poor compatibility between the material and the matrix, and low flame retardant efficiency.

The modified cyclodextrin is prepared by the following method:

(1) 18-22 parts by weight of cyclodextrins are added in the phosphoric acid of 95-105 parts by weight, stirred for 15-30min with the rotating speed of 600-1000rpm, then put into the reaction kettle of polytetrafluoroethylene lining, put into 90 Keep it in an oven at -100°C for 0.5-1.5h, centrifuge after the reaction, take the bottom precipitate for washing, and dry it in an oven at 55-65°C for 10-15h to obtain a cyclodextrin esterification intermediate;

(2) 17-21 parts by weight of the cyclodextrin esterification intermediate obtained in step (1) and 75-85 parts by weight of melamine are added to 480-520 parts by weight of deionized water, and the temperature is 90-100 ℃ at 1000-1500 rpm Stir at a high speed for 80-100min, centrifuge after the reaction, take the bottom precipitate for washing, and dry it in an oven at 70-90°C for 10-15h to obtain pre-modified cyclodextrin;

(3) 13-18 parts by weight of pre-modified cyclodextrin obtained in step (2) and 3-8 parts by weight of crosslinking agent are added to 90-110 parts by weight of absolute ethanol, and then put into polytetrafluoroethylene lining Put it in the oven at 75-85°C for 1.5-2.5h, centrifuge after the reaction, take the bottom precipitate for washing, and dry it in the oven at 60-80°C for 4-6h to obtain modified cyclodextrin.

The crosslinking agent is one or more of polymethyltriethoxysilane, n-octyltriethoxysilane and n-octyltriethoxysilane.

Preferably, the crosslinking agent is a mixture of polymethyltriethoxysilane and 4-pyridinetriethoxysilane, and the quality of the polymethyltriethoxysilane and 4-pyridinetriethoxysilane is The ratio is 3:(1-3).

In the present invention, the cyclodextrin is pre-modified by phosphoric acid and melamine. On the one hand, the particle size of the cyclodextrin is reduced, and the dispersibility of the cyclodextrin in the polypropylene matrix is improved. On the other hand, the phosphoric acid reacts with the cyclodextrin. A part of the hydroxyl groups on the surface of the cyclodextrin is consumed, making the cyclodextrin less hydrophilic.

Further, after the pre-modified cyclodextrin is modified with a cross-linking agent, the unreacted hydroxyl groups on the surface of the cyclodextrin continue to react with the ethoxy groups in the cross-linking agent during the pre-modification, and as the number of hydroxyl groups decreases, As a result, the modified cyclodextrin has changed from hydrophilic to hydrophobic, and the surface energy is greatly reduced, which further improves its compatibility and dispersion in the polypropylene matrix, thereby weakening the "wick" of glass fiber. effect”, making the composite more dense in structure.

The present invention uses both polymethyltriethoxysilane and 4-pyridinetriethoxysilane as a cross-linking agent. First, both contain ethoxy groups and can react with hydroxyl groups on cyclodextrin. , further reducing the polarity between cyclodextrin and polypropylene matrix; second, polymethyltriethoxysilane has a higher thermal degradation temperature, while 4-pyridinetriethoxysilane contains N atoms, which improves the modification N content in cyclodextrins. When used together, the thermal decomposition of modified cyclodextrin can be delayed, resulting in improved thermal stability.

Analysis of the flame retardant mechanism of the modified cyclodextrin of the present invention: in the first stage, the melamine structure in the modified cyclodextrin first decomposes, and inert gases such as CO ₂ , NH ₃ and H ₂ O are released, which can to a certain extent Dilute the oxygen concentration around the combustion zone; in the second stage, the phosphoric acid structure in the modified cyclodextrin and the cyclodextrin structure undergo thermal esterification to generate carbon residue with cross-linked structures (POP and POC groups); third In the first stage, under the induction of inert gas, the carbon residue gradually forms a dense, expanded and continuous carbon layer with a graphitized structure. The strong barrier effect of the carbon layer can effectively inhibit the heat and mass transfer between the combustion zone and the composite matrix. , and then realize the flame retardant properties of modified cyclodextrin.

Polypropylene composite material, prepared by:

S1. First, the polypropylene resin, glass fiber, modified cyclodextrin and polyethylene polyoctene elastomer are dried at 65-75 ° C for 10-15 hours, and then each component is weighed according to the proportion and put into the high mixer Mixing at 400-600rpm for 5-15min to obtain a mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 75-85 ° C for 10-15 hours, that is, The polypropylene composite material is obtained, and the extrusion process conditions are as follows: the rotational speed of the screw is 150-300 rpm, and the working temperature of the extrusion section is 120-210°C.

Further, the polypropylene composite material is prepared by the following method:

S1. First, dry polypropylene resin, glass fiber, modified cyclodextrin, composite antibacterial agent and polyethylene polyoctene elastomer at 65-75 ° C for 10-15 hours, then weigh each component according to the proportion, put into Mixing at 400-600rpm for 5-15min in the high mixer to obtain a mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 75-85 ° C for 10-15 hours, that is, The polypropylene composite material is obtained, and the extrusion process conditions are as follows: the rotational speed of the screw is 150-300 rpm, and the working temperature of the extrusion section is 120-210°C.

The invention has the following technical effects: the polypropylene composite material of the invention has good flame retardant performance and antibacterial performance. In the invention, a new type of hydrophobic cyclodextrin-based halogen-free intumescent flame retardant is prepared by combining green and sustainable biomass-based cyclodextrin and traditional intumescent flame retardant components, and the surface of the cyclodextrin is hydrophilic. The conversion of water to hydrophobicity greatly improves the compatibility and dispersibility between the cyclodextrin material and the polypropylene matrix, thereby promoting the improvement of the flame retardant efficiency.

Detailed ways

The above-mentioned content of the present invention will be described in further detail below in conjunction with specific embodiments, but it should not be understood that the scope of the above-mentioned subject matter of the present invention is limited to the following examples.

Introduction of some raw materials in this application:

Polyethylene polyoctene elastomer, brand Dow Spain, brand DE2300, density 1.16g/cm ³ , purchased from Foshan Ruisheng Plastic Co., Ltd.

Polypropylene resin, namely PP resin, CAS number: 9003-07-0, brand: L5E89, purchased from China National Petroleum Corporation.

Glass fiber, CAS number: 65997-17-3, using glass fiber chopped strands, purchased from Leshan Chuanwei New Materials Co., Ltd.

Cyclodextrin, β-cyclodextrin is used in the present invention, CAS number: 7585-39-9, purchased from Zhengzhou Kangyuan Chemical Products Co., Ltd.

Phosphoric acid, CAS number: 7664-38-2, purity: 85%, purchased from Jining Huipeng Chemical Co., Ltd.

Melamine, CAS No.: 108-78-1, was purchased from Shanghai McLean Biochemical Technology Co., Ltd.

Polymethyltriethoxysilane, density: 1.0 g/cm ³ , model: yn-303, purchased from Shandong Daosheng Chemical Technology Co., Ltd.

4-Pyridinetriethoxysilane, CAS No.: 166262-04-0, was purchased from Shanghai Qingliu Chemical Technology Center.

Benzyldimethyldodecylammonium bromide, CAS number: 7281-04-1, was purchased from Beijing Bailingwei Technology Co., Ltd.

Heparin sodium salt, CAS number: 9041-08-1, was purchased from Nanjing Dulai Biotechnology Co., Ltd.

Polyaminopropyl biguanide, CAS number: 133029-32-0, was purchased from Hubei Xinmingtai Chemical Co., Ltd.

Sodium palmitate, CAS number: 408-35-5, was purchased from Wuhan Rongcan Biotechnology Co., Ltd.

Example 1

The polypropylene composite material is composed of the following raw materials: 75wt% polypropylene resin, 20wt% glass fiber and 5wt% polyethylene polyoctene elastomer.

Polypropylene composite material, prepared by:

S1. First, the polypropylene resin, glass fiber and polyethylene polyoctene elastomer are dried at 70 ° C for 12 hours, then each component is weighed according to the proportion, put into a high mixer and mixed at a speed of 500 rpm for 10 minutes to obtain a mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 80 ° C for 12 hours to obtain a polypropylene composite Materials, the extrusion process conditions are: the screw speed is 250rpm, and the working temperature of the extrusion section is 170°C.

Example 2

The polypropylene composite material is composed of the following raw materials: 55wt% polypropylene resin, 20wt% glass fiber, 20wt% cyclodextrin and 5wt% polyethylene polyoctene elastomer.

Polypropylene composite material, prepared by:

S1. First, dry the polypropylene resin, glass fiber, cyclodextrin and polyethylene polyoctene elastomer at 70 °C for 12 hours, then weigh the components according to the proportion, put them into a high-speed mixer and mix at a speed of 500 rpm for 10 minutes , to get a mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 80 ° C for 12 hours to obtain a polypropylene composite Materials, the extrusion process conditions are: the screw speed is 250rpm, and the working temperature of the extrusion section is 170°C.

Comparative Example 1

The polypropylene composite material is composed of the following raw materials: 55wt% polypropylene resin, 20wt% glass fiber, 20wt% melamine and 5wt% polyethylene polyoctene elastomer.

Polypropylene composite material, prepared by:

S1. First, dry polypropylene resin, glass fiber, melamine and polyethylene polyoctene elastomer at 70°C for 12 hours, then weigh each component according to the proportion, put it into a high-speed mixer and mix at a speed of 500rpm for 10min to obtain mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 80 ° C for 12 hours to obtain a polypropylene composite Materials, the extrusion process conditions are: the screw speed is 250rpm, and the working temperature of the extrusion section is 170°C.

Example 3

The polypropylene composite material is composed of the following raw materials: 55wt% polypropylene resin, 20wt% glass fiber, 20wt% pre-modified cyclodextrin and 5wt% polyethylene polyoctene elastomer.

The pre-modified cyclodextrin is prepared by the following method:

(1) 20 parts by weight of cyclodextrin were added to 100 parts by weight of phosphoric acid, stirred for 20 min at a rotating speed of 800 rpm, then put into a polytetrafluoroethylene-lined reactor, put into an oven at 100 ° C and kept for 1 h, the reaction After centrifugation, the bottom precipitate was washed and dried in an oven at 60 °C for 12 h to obtain a cyclodextrin esterification intermediate;

(2) 18 parts by weight of the cyclodextrin esterification intermediate obtained in step (1) and 80 parts by weight of melamine were added to 500 parts by weight of deionized water, stirred for 90min at a rotating speed of 1200rpm at a temperature of 95°C, and centrifuged after the reaction was finished, The bottom precipitate was washed and dried in an oven at 80°C for 12 hours to obtain pre-modified cyclodextrin.

Polypropylene composite material, prepared by:

S1. First, dry the polypropylene resin, glass fiber, pre-modified cyclodextrin and polyethylene polyoctene elastomer at 70°C for 12 hours, then weigh the components according to the proportion, and put them into the high mixer at 500rpm. Mixing at rotating speed for 10min to obtain a mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 80 ° C for 12 hours to obtain a polypropylene composite Materials, the extrusion process conditions are: the screw speed is 250rpm, and the working temperature of the extrusion section is 170°C.

Example 4

The polypropylene composite material is composed of the following raw materials: 55wt% polypropylene resin, 20wt% glass fiber, 20wt% modified cyclodextrin and 5wt% polyethylene polyoctene elastomer.

The modified cyclodextrin is prepared by the following method:

(1) 20 parts by weight of cyclodextrin were added to 100 parts by weight of phosphoric acid, stirred for 20 min at a rotating speed of 800 rpm, then put into a polytetrafluoroethylene-lined reactor, put into an oven at 100 ° C and kept for 1 h, the reaction After centrifugation, the bottom precipitate was washed and dried in an oven at 60 °C for 12 h to obtain a cyclodextrin esterification intermediate;

(2) 18 parts by weight of the cyclodextrin esterification intermediate obtained in step (1) and 80 parts by weight of melamine were added to 500 parts by weight of deionized water, stirred for 90min at a rotating speed of 1200rpm at a temperature of 95°C, and centrifuged after the reaction was finished, The bottom precipitate was washed and dried in an oven at 80 °C for 12 h to obtain pre-modified cyclodextrin;

(3) 15 parts by weight of the pre-modified cyclodextrin obtained in step (2) and 5 parts by weight of polymethyltriethoxysilane were added to 100 parts by weight of absolute ethanol, and then put into a polytetrafluoroethylene lined The reaction kettle was placed in an oven at 80°C for 2 hours, centrifuged after the reaction, and the bottom precipitate was washed and dried in an oven at 70°C for 5 hours to obtain modified cyclodextrin.

Polypropylene composite material, prepared by:

S1. First, dry polypropylene resin, glass fiber, modified cyclodextrin and polyethylene polyoctene elastomer at 70°C for 12 hours, then weigh each component according to the proportion, and put it into a high-speed mixer at a speed of 500rpm Mix for 10min to obtain a mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 80 ° C for 12 hours to obtain a polypropylene composite Materials, the extrusion process conditions are: the screw speed is 250rpm, and the working temperature of the extrusion section is 170°C.

Example 5

The polypropylene composite material is composed of the following raw materials: 55wt% polypropylene resin, 20wt% glass fiber, 20wt% modified cyclodextrin and 5wt% polyethylene polyoctene elastomer.

The modified cyclodextrin is prepared by the following method:

(1) 20 parts by weight of cyclodextrin were added to 100 parts by weight of phosphoric acid, stirred for 20 min at a rotating speed of 800 rpm, then put into a polytetrafluoroethylene-lined reactor, put into an oven at 100 ° C and kept for 1 h, the reaction After centrifugation, the bottom precipitate was washed and dried in an oven at 60 °C for 12 h to obtain a cyclodextrin esterification intermediate;

(2) 18 parts by weight of the cyclodextrin esterification intermediate obtained in step (1) and 80 parts by weight of melamine were added to 500 parts by weight of deionized water, stirred at a rotating speed of 1200rpm for 90min at a temperature of 95°C, and centrifuged after the reaction was finished, The bottom precipitate was washed and dried in an oven at 80 °C for 12 h to obtain pre-modified cyclodextrin;

(3) 15 parts by weight of the pre-modified cyclodextrin obtained in step (2) and 5 parts by weight of 4-pyridinetriethoxysilane were added to 100 parts by weight of absolute ethanol, and then put into a polytetrafluoroethylene-lined The reaction kettle was placed in an oven at 80°C for 2 hours, centrifuged after the reaction, and the bottom precipitate was washed and dried in an oven at 70°C for 5 hours to obtain modified cyclodextrin.

Polypropylene composite material, prepared by:

S1. First, dry polypropylene resin, glass fiber, modified cyclodextrin and polyethylene polyoctene elastomer at 70°C for 12 hours, then weigh each component according to the proportion, and put it into a high-speed mixer at a speed of 500rpm Mix for 10min to obtain a mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 80 ° C for 12 hours to obtain a polypropylene composite Materials, the extrusion process conditions are: the screw speed is 250rpm, and the working temperature of the extrusion section is 170°C.

Example 6

The polypropylene composite material is composed of the following raw materials: 55wt% polypropylene resin, 20wt% glass fiber, 20wt% modified cyclodextrin and 5wt% polyethylene polyoctene elastomer.

The modified cyclodextrin is prepared by the following method:

(1) 20 parts by weight of cyclodextrin were added to 100 parts by weight of phosphoric acid, stirred for 20 min at a rotating speed of 800 rpm, then put into a polytetrafluoroethylene-lined reactor, put into an oven at 100 ° C and kept for 1 h, the reaction After centrifugation, the bottom precipitate was washed and dried in an oven at 60 °C for 12 h to obtain a cyclodextrin esterification intermediate;

(2) 18 parts by weight of the cyclodextrin esterification intermediate obtained in step (1) and 80 parts by weight of melamine were added to 500 parts by weight of deionized water, stirred at a rotating speed of 1200rpm for 90min at a temperature of 95°C, and centrifuged after the reaction was finished, The bottom precipitate was washed and dried in an oven at 80 °C for 12 h to obtain pre-modified cyclodextrin;

(3) 15 parts by weight of pre-modified cyclodextrin obtained in step (2), 3 parts by weight of polymethyltriethoxysilane and 2 parts by weight of 4-pyridinetriethoxysilane were added to 100 parts by weight of absolute ethanol Then put it into a PTFE-lined reaction kettle, put it in an oven at 80 °C for 2 hours, centrifuge after the reaction, take the bottom precipitate for washing, and dry it in an oven at 70 °C for 5 hours to obtain the modified cyclodextrin .

Polypropylene composite material, prepared by:

S1. First, dry polypropylene resin, glass fiber, modified cyclodextrin and polyethylene polyoctene elastomer at 70°C for 12 hours, then weigh each component according to the proportion, and put it into a high-speed mixer at a speed of 500rpm Mix for 10min to obtain a mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 80 ° C for 12 hours to obtain a polypropylene composite Materials, the extrusion process conditions are: the screw speed is 250rpm, and the working temperature of the extrusion section is 170°C.

Example 7

The polypropylene composite material is composed of the following raw materials: 52wt% polypropylene resin, 20wt% glass fiber, 20wt% modified cyclodextrin, 3wt% composite antibacterial agent and 5wt% polyethylene polyoctene elastomer.

The modified cyclodextrin is prepared by the following method:

(1) 20 parts by weight of cyclodextrin were added to 100 parts by weight of phosphoric acid, stirred for 20 min at a rotating speed of 800 rpm, then put into a polytetrafluoroethylene-lined reactor, put into an oven at 100 ° C and kept for 1 h, the reaction After centrifugation, the bottom precipitate was washed and dried in an oven at 60 °C for 12 h to obtain a cyclodextrin esterification intermediate;

(2) 18 parts by weight of the cyclodextrin esterification intermediate obtained in step (1) and 80 parts by weight of melamine were added to 500 parts by weight of deionized water, stirred for 90min at a rotating speed of 1200rpm at a temperature of 95°C, and centrifuged after the reaction was finished, The bottom precipitate was washed and dried in an oven at 80 °C for 12 h to obtain pre-modified cyclodextrin;

(3) 15 parts by weight of pre-modified cyclodextrin obtained in step (2), 3 parts by weight of polymethyltriethoxysilane and 2 parts by weight of 4-pyridinetriethoxysilane were added to 100 parts by weight of absolute ethanol Then put it into a PTFE-lined reaction kettle, put it in an oven at 80 °C for 2 hours, centrifuge after the reaction, take the bottom precipitate for washing, and dry it in an oven at 70 °C for 5 hours to obtain the modified cyclodextrin .

The composite antibacterial agent is prepared by the following method: 0.8 parts by weight of polyaminopropyl biguanide and 1.2 parts by weight of benzyl dimethyl dodecyl ammonium bromide are added to 98 parts by weight of water for ultrasonic treatment for 5 minutes, and the ultrasonic frequency is 20 kHz. , ultrasonic power 350W; then add 1 weight part of heparin sodium salt, 1 weight part of sodium palmitate and stir for 15min, stirring speed 120rpm; reduce pressure concentration, freeze-dry, namely obtain composite antibacterial agent.

Polypropylene composite material, prepared by:

S1. First, the polypropylene resin, glass fiber, modified cyclodextrin, composite antibacterial agent and polyethylene polyoctene elastomer are dried at 70 ° C for 12 hours, and then each component is weighed according to the proportion and put into the high mixer Mixing at 500rpm for 10min to obtain a mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 80 ° C for 12 hours to obtain a polypropylene composite Materials, the extrusion process conditions are: the screw speed is 250rpm, and the working temperature of the extrusion section is 170°C. According to the standard GB/T 31402-2015, the antibacterial test was carried out on the polypropylene composite material of Example 7; The rate is 99.6%. The flame retardancy (LOI) of the polypropylene composite of Example 7 was 34.9%.

Comparative Example 2

The polypropylene composite material is composed of the following raw materials: 52wt% polypropylene resin, 20wt% glass fiber, 20wt% modified cyclodextrin, 3wt% composite antibacterial agent and 5wt% polyethylene polyoctene elastomer.

The modified cyclodextrin is prepared by the following method:

(1) 20 parts by weight of cyclodextrin were added to 100 parts by weight of phosphoric acid, stirred for 20 min at a rotating speed of 800 rpm, then put into a polytetrafluoroethylene-lined reactor, put into an oven at 100 ° C and kept for 1 h, the reaction After centrifugation, the bottom precipitate was washed and dried in an oven at 60 °C for 12 h to obtain a cyclodextrin esterification intermediate;

(2) 18 parts by weight of the cyclodextrin esterification intermediate obtained in step (1) and 80 parts by weight of melamine were added to 500 parts by weight of deionized water, stirred for 90min at a rotating speed of 1200rpm at a temperature of 95°C, and centrifuged after the reaction was finished, The bottom precipitate was washed and dried in an oven at 80 °C for 12 h to obtain pre-modified cyclodextrin;

(3) 15 parts by weight of pre-modified cyclodextrin obtained in step (2), 3 parts by weight of polymethyltriethoxysilane and 2 parts by weight of 4-pyridinetriethoxysilane were added to 100 parts by weight of absolute ethanol Then put it into a PTFE-lined reaction kettle, put it in an oven at 80 °C for 2 hours, centrifuge after the reaction, take the bottom precipitate for washing, and dry it in an oven at 70 °C for 5 hours to obtain the modified cyclodextrin .

The composite antibacterial agent is prepared by the following method: take 2 parts by weight of benzyl dimethyl dodecyl ammonium bromide and add it to 98 parts by weight of water for ultrasonic treatment for 5min, ultrasonic frequency 20kHz, ultrasonic power 350W; then add 2 weight parts Parts of heparin sodium salt were stirred for 15 min at a stirring speed of 120 rpm; concentrated under reduced pressure and freeze-dried to obtain a composite antibacterial agent.

Polypropylene composite material, prepared by:

S1. First, the polypropylene resin, glass fiber, modified cyclodextrin, composite antibacterial agent and polyethylene polyoctene elastomer are dried at 70 ° C for 12 hours, and then each component is weighed according to the proportion and put into the high mixer Mixing at 500rpm for 10min to obtain a mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 80 ° C for 12 hours to obtain a polypropylene composite Materials, the extrusion process conditions are: the screw speed is 250rpm, and the working temperature of the extrusion section is 170°C. According to the standard GB/T 31402-2015, the antibacterial test was carried out on the polypropylene composite material of Comparative Example 2; The rate is 97.5%.

Comparative Example 3

The polypropylene composite material is composed of the following raw materials: 52wt% polypropylene resin, 20wt% glass fiber, 20wt% modified cyclodextrin, 3wt% composite antibacterial agent and 5wt% polyethylene polyoctene elastomer.

The modified cyclodextrin is prepared by the following method:

(1) 20 parts by weight of cyclodextrin were added to 100 parts by weight of phosphoric acid, stirred for 20 min at a rotating speed of 800 rpm, then put into a polytetrafluoroethylene-lined reactor, put into an oven at 100 ° C and kept for 1 h, the reaction After centrifugation, the bottom precipitate was washed and dried in an oven at 60 °C for 12 h to obtain a cyclodextrin esterification intermediate;

(2) 18 parts by weight of the cyclodextrin esterification intermediate obtained in step (1) and 80 parts by weight of melamine were added to 500 parts by weight of deionized water, stirred for 90min at a rotating speed of 1200rpm at a temperature of 95°C, and centrifuged after the reaction was finished, The bottom precipitate was washed and dried in an oven at 80 °C for 12 h to obtain pre-modified cyclodextrin;

(3) 15 parts by weight of pre-modified cyclodextrin obtained in step (2), 3 parts by weight of polymethyltriethoxysilane and 2 parts by weight of 4-pyridinetriethoxysilane were added to 100 parts by weight of absolute ethanol Then put it into a PTFE-lined reaction kettle, put it in an oven at 80 °C for 2 hours, centrifuge after the reaction, take the bottom precipitate for washing, and dry it in an oven at 70 °C for 5 hours to obtain the modified cyclodextrin .

The composite antibacterial agent is prepared by the following method: take 2 parts by weight of polyaminopropyl biguanide and add it to 98 parts by weight of water for ultrasonic treatment for 5min, ultrasonic frequency 20kHz, ultrasonic power 350W; then add 2 weight parts of sodium palmitate and stir for 15min, The stirring speed is 120 rpm; the compound antibacterial agent is obtained by concentrating under reduced pressure and freeze-drying.

Polypropylene composite material, prepared by:

S1. First, the polypropylene resin, glass fiber, modified cyclodextrin, composite antibacterial agent and polyethylene polyoctene elastomer are dried at 70 ° C for 12 hours, and then each component is weighed according to the proportion and put into the high mixer Mixing at 500rpm for 10min to obtain a mixture;

S2. Put the mixture obtained in S1 into the twin-screw extruder for melt extrusion and granulation. The granulated material is sent to the silo through the air conveying system, and is dried at a temperature of 80 ° C for 12 hours to obtain a polypropylene composite Materials, the extrusion process conditions are: the screw speed is 250rpm, and the working temperature of the extrusion section is 170°C. According to the standard GB/T 31402-2015, the antibacterial test was carried out on the polypropylene composite material of Comparative Example 3; The rate was 97.2%.

Test Example 1

The polypropylene composite materials prepared in Examples 1-6 and Comparative Example 1 were injection-molded by a plastic injection molding machine (the nozzle temperature was 230° C.).

Limiting oxygen index (LOI) test: refer to the national standard GB/T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics Part 2: Room Temperature Test". The size of the sample is 80mm in length, 10mm in width and 4mm in thickness. It was adjusted for 24h under the conditions of temperature 25°C and humidity 40%, and a score line was drawn at 50mm of the sample. Use JF-3 oxygen index tester to test.

Vertical burning (UL-94) test: refer to GB/T 2408-2008 "Determination of Plastics Burning Properties Horizontal and Vertical Method", and use test method B: vertical burning (V). The size of the sample is 125mm in length, 13mm in width and 3mm in thickness; the sample is conditioned for 24h at a temperature of 25°C and a humidity of 40%. The test was carried out with the SH5300 vertical combustion tester.

Each group of samples was tested five times, and the average value was taken as the test result.

Table 1 Test results of flame retardant performance

It can be seen from the above results that, compared with Example 1, the flame retardant properties of the composite material were slightly improved by adding cyclodextrin in Example 2, which may be due to the lower content of acid source and gas source in the material. The improvement of the flame retardant performance of the composite material in Example 3 is due to the synergistic effect of the thermochemical reactions among the phosphoric acid, melamine and cyclodextrin in the pre-modified cyclodextrin, which can release an effective carbon layer and play a role in preventing combustion effect. In Examples 4-6, the cross-linking agent was used to modify the cyclodextrin, and the flame retardancy of the composite material was further improved, which may be due to the following reasons: the modified cyclodextrin has stronger hydrophobicity, which leads to its dispersibility in the polypropylene matrix It is better than pre-modified cyclodextrin, and the cross-linking agent plays a certain role in promoting the carbonization process.

Test case 2

The polypropylene composite materials prepared in Examples 1-6 and Comparative Example 1 were injection-molded by a plastic injection molding machine (the nozzle temperature was 230° C.).

Moisture barrier performance test: refer to GB/T 1462-2005 "Test method for water absorption of fiber reinforced plastics", and use method 2 to test. Specific experimental method: prepare a square piece with a side length of 50 mm and a thickness of 4 mm as a sample, and prepare 5 samples for each group of examples; At room temperature, weigh the mass of each sample (m ₁ ) immediately after taking it out; Immediately immerse the weighed sample in boiled distilled water for 30 minutes, then move it to room temperature distilled water to cool for 15 minutes, take it out and remove the surface with clean filter paper Immediately after moisture, weigh the sample mass (m ₂ ); the measurement result is expressed by the water absorption per unit surface area (m _s ), and the calculation formula is: m _s =m _a /S, m _a =m ₂ -m ₁ , where S is The initial total surface area of the sample, the unit is cm ² , the unit of m ₁ , m ₂ , and ma is _g , and the unit of m _s is g/cm ² . The moisture barrier performance of the material is evaluated by the average water absorption per unit surface area of the sample. The smaller the value, the better the moisture barrier performance. The experimental results are shown in the table below.

Table 2 Test results of moisture barrier properties

The modified cyclodextrin used in the present invention has a smaller particle size, and especially after being modified by a cross-linking agent, the surface of the cyclodextrin is converted into hydrophobicity, which greatly improves the modified cyclodextrin, glass fiber and polypropylene matrix. Compatibility between them, thereby weakening the "wick effect" of the glass fiber and making the structure of the composite material more compact. Therefore, while the flame retardant performance is improved, the moisture barrier performance is also improved.

The preferred embodiments of the present invention have been described above in detail. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative efforts. Therefore, any technical solutions that can be obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the prior art according to the concept of the present invention shall fall within the protection scope determined by the claims.

Claims (2)

1. The polypropylene composite material is characterized by comprising the following raw materials: 18-23 wt% of glass fiber, 15-24 wt% of modified cyclodextrin, 2-6 wt% of composite antibacterial agent, 3-7 wt% of polyethylene polyoctene elastomer and the balance of polypropylene resin;

the composite antibacterial agent is prepared by the following method: adding 0.5-1 weight part of poly aminopropyl biguanide and 1-1.5 weight parts of benzyl dimethyl dodecyl ammonium bromide into 95-100 weight parts of water, and performing ultrasonic treatment for 3-6min at an ultrasonic frequency of 20-30kHz and an ultrasonic power of 300-500W; then adding 0.5-1.5 parts by weight of heparin sodium salt and 0.5-1.5 parts by weight of sodium palmitate, stirring for 10-20min at the stirring speed of 100-150 rpm; concentrating under reduced pressure, and lyophilizing to obtain composite antibacterial agent;

the modified cyclodextrin is prepared by the following method:

(1) adding 18-22 parts by weight of cyclodextrin into 95-105 parts by weight of phosphoric acid, stirring for 15-30min at the rotation speed of 1000rpm of 600-;

(2) adding 17-21 parts by weight of the cyclodextrin esterification intermediate obtained in the step (1) and 75-85 parts by weight of melamine into 480-520 parts by weight of deionized water, stirring at 90-100 ℃ and 1500rpm for 80-100min, centrifuging after the reaction is finished, taking the bottom precipitate, washing, and drying in an oven at 70-90 ℃ for 10-15h to obtain pre-modified cyclodextrin;

(3) adding 13-18 parts by weight of the pre-modified cyclodextrin obtained in the step (2) and 3-8 parts by weight of a cross-linking agent into 90-110 parts by weight of absolute ethyl alcohol, then placing the mixture into a reaction kettle with a polytetrafluoroethylene lining, placing the reaction kettle into a 75-85 ℃ drying oven for 1.5-2.5h, centrifuging after the reaction is finished, taking bottom precipitate, washing, and drying in the 60-80 ℃ drying oven for 4-6h to obtain modified cyclodextrin; the cross-linking agent is a mixture of polymethyl triethoxy silane and 4-pyridine triethoxy silane.

2. The polypropylene composite of claim 1, prepared by a process comprising:

s1, drying the polypropylene resin, the glass fiber, the modified cyclodextrin, the composite antibacterial agent and the polyethylene polyoctene elastomer at 65-75 ℃ for 10-15h, weighing the components according to the proportion, and putting the components into a high-speed mixer to mix for 5-15min at the rotating speed of 400-600rpm to obtain a mixture;

s2, putting the mixture obtained in the step S1 into a double-screw extruder, performing melt extrusion granulation, feeding the granulated material into a storage bin through an air conveying system, and drying at the temperature of 75-85 ℃ for 10-15 hours to obtain the polypropylene composite material, wherein the extrusion process conditions are as follows: the rotation speed of the screw is 150-300rpm, and the working temperature of the extrusion section is 120-210 ℃.