CN104725797B - Method for preparing flame-retardant plastic composite material - Google Patents

Abstract

The invention discloses a method for preparing a flame-retardant plastic composite material. First, polybutylene terephthalate PBT is dried in a blast drying oven at 110-120°C for 4-6 hours, and acrylonitrile- Butadiene-styrene copolymer ABS is dried in a blast drying oven at 60-70°C for 2-4 hours; then weigh the corresponding raw materials according to the set mass percentage, and add the weighed raw materials to the high-speed Mixing in a mixer; adding the mixture into a twin-screw extruder for melting and kneading, cooling in a water tank and pelletizing by a pelletizer to obtain the flame-retardant plastic composite material. The composite material prepared by the method has high impact toughness, good processing performance, and excellent flame retardancy, and can be used in the fields of automobiles, home appliances, electronic information and the like.

Description

A kind of preparation method of flame retardant plastic composite material

technical field

The invention relates to the technical field of engineering plastic alloys, in particular to a method for preparing a flame-retardant plastic composite material.

Background technique

In recent years, the plastics industry has made great progress, and engineering plastics, especially ABS, have been standardized in the fields of electrical appliances, transportation, and computers. ABS is the most used engineering plastic. It is an acrylonitrile-butadiene-styrene copolymer, which has good fluidity, high mechanical properties, and good surface quality. However, ABS itself is easy to burn and not resistant to aging (easy to turn yellow) ), low heat resistance, and high price also limit its application. Traditional flame retardant ABS uses bromine-containing flame retardants compounded with antimony-containing compounds. However, bromide will produce toxic gases during combustion, and antimony trioxide is also toxic, causing negative effects on human health and the environment.

In order to realize the environmentally friendly halogen-free flame retardant of ABS, many researchers have conducted research, mainly through hydroxides (such as aluminum hydroxide, magnesium hydroxide) or phosphorus-containing flame retardants (such as red phosphorus and phosphate, etc.) Instead of bromide and antimony trioxide. However, the flame retardant effect of hydroxide is poor, and a large amount needs to be added, which leads to the decrease of ABS process fluidity and the deterioration of mechanical properties, so it cannot be used. As a new type of green flame retardant system, the flame retardant system containing nitrogen and phosphorus has high flame retardant efficiency and is the main trend to replace bromine-containing compounds at present. In addition, PBT (polybutylene terephthalate) has the characteristics of high heat resistance, high strength, and good aging resistance, and its price is relatively low. It is also a widely used engineering plastic, but its toughness is poor, and its processing flow Due to the poor compatibility of PBT and ABS, the performance of pure blends is poor, especially the impact toughness is low, so compatibilization and toughening are required.

The flame-retardant PBT/ABS alloy material in the prior art is either not halogen-free, environmentally friendly, flame-retardant, or has low impact toughness, or poor fluidity, and its application range is not wide.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a flame-retardant plastic composite material. The composite material prepared by this method has high impact toughness and good processing performance, and has excellent flame-retardant performance at the same time. It can be used in automobiles, Used in home appliances, electronic information and other fields.

A method for preparing a flame-retardant plastic composite material, the method comprising:

First dry polybutylene terephthalate PBT in a blast drying oven at 110-120°C for 4-6 hours, and dry acrylonitrile-butadiene-styrene copolymer ABS at 60-70°C Dry in a blast drying oven for 2 to 4 hours;

Then weigh the corresponding raw material according to the set mass percentage, and add the weighed raw material into the high-speed mixer for mixing; wherein, the mass percentage of each component of the raw material is: 30-50% PBT, 20% ～35% ABS, 1～5% composite compatibilizer, 1～5% composite toughener, 10～30% composite flame retardant, 0.5～2% composite lubricant, 0.3～0.6% Composite antioxidant, 0.1-1% silicone oil, 0.1-1% polytetrafluoroethylene and 0.1-0.5% ethyltriphenylphosphine bromide;

Then, the mixture is added into a twin-screw extruder for melting and kneading, cooling in a water tank and pelletizing by a pelletizer to obtain the flame-retardant plastic composite material.

It can be seen from the above-mentioned technical solution provided by the present invention that the composite material prepared by this method has high impact toughness and good processing performance, and has excellent flame retardancy at the same time, and can be used in automobiles, home appliances, electronic information, etc. used in the field.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without making creative efforts.

Fig. 1 is a schematic flow chart of the preparation method of the flame-retardant plastic composite material provided by the embodiment of the present invention;

Fig. 2 is a schematic structural view of a twin-screw extruder provided by an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The method described in the embodiment of the present invention uses a phosphorus-containing flame retardant, and combines it with a new type of elastomer-polyphosphazene containing a large amount of nitrogen, and compound novolak resin as a flame-retardant additive for PBT/ABS, and is equipped with a compound compatible agent, composite toughening agent and composite lubricant to prepare environmentally friendly flame-retardant plastic composite materials, which greatly improves the flame-retardant performance, and at the same time has high fluidity and high toughness. It can be used in home appliances, automobiles, electronics, Electrical and information products and other fields. The embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Figure 1 is a schematic flow chart of the preparation method of the flame-retardant plastic composite material provided by the embodiment of the present invention. The preparation method includes:

Step 11: first dry polybutylene terephthalate PBT in a blast drying oven at 110-120°C for 4-6 hours, and dry acrylonitrile-butadiene-styrene copolymer ABS at 60- Dry in a blast drying oven at 70°C for 2 to 4 hours;

In a specific implementation, the intrinsic viscosity of the PBT used is 0.75-0.95 dl/g. Here, the intrinsic viscosity is a sign of molecular weight. If the molecular weight of PBT is too low, the impact toughness of the alloy will be low; otherwise, if the molecular weight of PBT is too high, the fluidity of the alloy will be poor.

The ABS used is a high-impact grade with a melt index (MI) between 1 and 5g/10min (200°C, 5kgf). Blending high-impact ABS and PBT can obtain engineering plastic alloys with high impact toughness.

Step 12: Weigh the corresponding raw materials according to the set mass percentage, and add the weighed raw materials into the high-speed mixer for mixing;

In this step, it is specifically possible to mix at high speed for 1 minute. The mass percentage of each component of the above raw materials is: 30-50% of PBT, 20-35% of ABS, 1-5% of composite compatibilizer, 1-5% of composite toughening agent, 10-30% of composite Flame retardant, 0.5-2% compound lubricant, 0.3-0.6% compound antioxidant, 0.1-1% silicone oil, 0.1-1% polytetrafluoroethylene and 0.1-0.5% ethyl triphenyl Phosphorus bromide;

In the specific implementation, the composite compatibilizer used is styrene-maleic anhydride copolymer SMA, ethylene butyl acrylate copolymer PTW and styrene-acrylonitrile-glycidyl methacrylate terpolymer SAG according to 1 : 1:1 mass ratio of the mixed mixture. Here, PTW itself has impact resistance at minus 40 degrees, and the material is flexible and can be used as a toughening agent; at the same time, EBA has high polarity and good compatibility with various polymers. Interfacial adhesion also contributes. The epoxy group on the SAG can react with the terminal carboxyl group of PBT to play a role of compatibilization. The combination of the three has a synergistic effect.

The composite toughening agent used is high rubber powder, methyl methacrylate-butadiene-styrene copolymer MBS with a core-shell structure and ethylene vinyl acetate copolymer EVA mixed in a mass ratio of 1:1:1 The final mixture; wherein, the butadiene content in the high rubber powder is 40-60 wt%, and the VA content in the EVA is 22-30 wt%. Here, high rubber powder can be considered as ABS powder with extremely high rubber content, which has good compatibility with ABS and outstanding toughening effect. MBS has a core-shell structure. The shell is a methacrylate copolymer, which has good compatibility with PBT and ABS. The core is a butadiene-styrene copolymer with a high rubber content, which has an excellent toughening effect. EVA not only has a good toughening effect, but also can improve the processing fluidity of the alloy. The combination of the three has a synergistic effect.

The composite flame retardant used is aluminum ethyl hypophosphite, zinc borate, novolac resin (softening point 75-90°C) and polyphenoxyphosphazene (number-average molecular weight above 40000) according to the ratio of 2:1:1: 0.5 mass ratio of the mixed mixture. Here, aluminum ethyl hypophosphite is a new type of halogen-free phosphorus-containing flame retardant, especially for polyester (PBT, etc.) with excellent flame retardant effect; zinc borate also has smoke suppression effect; novolac resin can increase the char formation rate , so that it has a flame-retardant effect; due to the addition of a large amount of flame retardant, the impact toughness of the composite material decreases, and the polyphosphazene elastomer not only has excellent flame retardancy for alloys, but also has excellent toughening effect, and the toughening effect is good . Therefore, the composite flame retardant is a phosphorus-nitrogen composite, and at the same time has a high char formation rate and good smoke suppression, and has a synergistic effect.

The composite lubricant used is a mixture of ethylene bis stearamide EBS, carnauba wax and oxidized polyethylene wax in a mass ratio of 1:1:1. Here, EBS and carnauba wax can increase fluidity and surface quality, and oxidized polyethylene wax can also promote the dispersion of flame retardants. The combination of the three has a synergistic effect.

The composite antioxidant used is antioxidant tetraerythritol ester (i.e. tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester) and triphosphite (i.e. three [ 2.4-di-tert-butylphenyl] phosphite) is mixed according to the mass ratio of 1:2.

The silicone oil used is dimethyl silicone oil with a viscosity of 1000-5000 mPa.s, preferably 1500-3000 mPa.s. Here, due to the addition of a large amount of flame retardant, the fluidity of the composite material will be affected, so silicone oil is added to improve the process fluidity of the composite material, and silicone oil has a certain flame retardant effect on ABS.

The polytetrafluoroethylene used is in powder form with an average particle diameter of 3-8 μm. Adding polytetrafluoroethylene here can suppress dripping, so as to achieve the UL-94V0 flame retardant level.

The use of ethyltriphenylphosphine bromide can catalyze the reaction between epoxy groups and carboxyl groups on PBT, thereby enhancing the compatibilization effect of SAG.

Step 13: adding the mixture into a twin-screw extruder for melting and kneading, cooling in a water tank, and pelletizing by a pelletizer to obtain the flame-retardant plastic composite material.

In this step, the twin-screw extruder is an intermeshing parallel co-rotating twin-screw extruder;

As shown in Figure 2, it is a schematic structural view of the twin-screw extruder provided by the embodiment of the present invention. In Figure 2: the length-to-diameter ratio of the screw is 36-44, the combination of the screws is a medium shear rate combination, and the twin-screw extrusion The temperature of the pellets is between 180 and 250°C. Here, the twin-screw granulation temperature should not be too high, and the shear force during mixing and granulation should not be too strong, otherwise it will easily cause the decomposition and scorch of ABS, which will lead to yellowing of the composite material, poor mechanical properties and no use value.

After modification by the composite compatibilizer, composite toughening agent, composite flame retardant and composite lubricant, the prepared PBT/ABS alloy material has high melt flow rate and high impact strength, and the comprehensive properties of the composite material Greatly improved, the dimensional stability of the prepared product is increased, has excellent flame retardancy, and can be used in the fields of automobiles, home appliances, and electronic information.

For ease of understanding, the implementation process of the present invention will be further described below in conjunction with specific implementation, and the following are the processing conditions for sample preparation in this implementation:

SZ-900/NB injection machine is used to injection mold standard samples, molding process conditions: injection temperature (feeding port) 220/230/235/230°C (nozzle), injection pressure 30-50MPa, holding time 8s, cooling time 20s .

The formulation of this implementation 1-3 is shown in Table 1 below:

Table 1 Formula table for implementing 1-3

Then according to the preparation method provided in the above examples, first dry PBT in a blast drying oven at 110-120°C for 4-6 hours, and dry ABS in a blast drying oven at 60-70°C for 2-4 hours; then press Weigh each component according to the formula ratio, add it to a high-speed mixer, and mix it at a high speed for 1 minute; then add the mixture to a twin-screw extruder for melting and kneading, cool it in a water tank, and pelletize it with a pelletizer to obtain the flame-retardant plastic composite material.

The screw extruder used is an intermeshing parallel co-rotating twin-screw extruder, the screw length-to-diameter ratio is 36-44, and the screw combination is a combination of medium shear rate; the temperature of twin-screw extrusion granulation is 180- Between 250°C (the process conditions are shown in Table 2).

Table 2 granulation process parameters of implementation 1-3

Then the composite material obtained is detected according to the following performance test methods:

Tensile strength and elongation at break: according to GB/T 1040-2006 standard.

Bending strength and flexural modulus: according to GB/T 9341-2008 standard.

Notched impact performance: according to GB/T1043-2008 standard.

Heat distortion temperature: in accordance with GB/T1634-2004 standard; maximum bending normal stress 1.82MPa, heating rate: 2°C/min.

Flame retardancy: vertical burning performance, tested according to UL-94 vertical burning standard, 3.2mm thick and 1.6mm thick specimens.

Oxygen index test: according to GB/T2406-2008 standard.

Molding shrinkage: according to GB/T 15585-1995 standard.

The performance of the composite material obtained by implementing 1-3 is shown in Table 3:

Table 3 Properties of Composite Materials

It can be seen from the above table 3 that after modification by composite compatibilizer, composite toughener, composite flame retardant and composite lubricant, the prepared composite material has high melt flow rate and high impact strength, composite The comprehensive performance of the material has been greatly improved, and the dimensional stability of the prepared product has increased, indicating that the composite compatibilizer, composite toughener and composite lubricant have played a very good role, and can be used to form large-scale parts, such as electrical casings, Auto parts, etc., overcome the shortcomings of poor fluidity of flame-retardant PBT/ABS alloy materials in the past, and at the same time achieve halogen-free environmental protection and flame retardancy, which has a positive contribution to environmental protection.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily conceive of changes or changes within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (5)

1. A preparation method for flame-retardant plastic composite material, characterized in that, the method comprises: First dry polybutylene terephthalate PBT in a blast drying oven at 110-120°C for 4-6 hours, and dry acrylonitrile-butadiene-styrene copolymer ABS at 60-70°C Dry in a blast drying oven for 2 to 4 hours; Then weigh the corresponding raw material according to the set mass percentage, and add the weighed raw material into the high-speed mixer for mixing; wherein, the mass percentage of each component of the raw material is: 30-50% PBT, 20% ～35% ABS, 1～5% composite compatibilizer, 1～5% composite toughener, 10～30% composite flame retardant, 0.5～2% composite lubricant, 0.3～0.6% Composite antioxidant, 0.1-1% silicone oil, 0.1-1% polytetrafluoroethylene and 0.1-0.5% ethyltriphenylphosphine bromide; The mixture is then added to a twin-screw extruder for melt kneading, cooling in a water tank, and pelletizing by a pelletizer to obtain the flame-retardant plastic composite material; Wherein, the composite compatibilizer adopted is styrene-maleic anhydride copolymer SMA, ethylene butyl acrylate copolymer PTW and styrene-acrylonitrile-glycidyl methacrylate terpolymer SAG according to 1:1: The mass ratio of 1 is the mixed mixture; The composite toughening agent used is high rubber powder, methyl methacrylate-butadiene-styrene copolymer MBS with a core-shell structure and ethylene vinyl acetate copolymer EVA mixed in a mass ratio of 1:1:1 The final mixture; wherein, the butadiene content in the high rubber powder is 40-60wt%, and the VA content in the EVA is 22-30wt%; The composite flame retardant used is a mixture of aluminum ethyl hypophosphite, zinc borate, novolak resin and polyphenoxyphosphazene mixed in a mass ratio of 2:1:1:0.5; The composite lubricant used is a mixture of ethylene bis stearamide EBS, carnauba wax and oxidized polyethylene wax in a mass ratio of 1:1:1; The composite antioxidant used is a mixture of antioxidant tetraerythritol ester and triphosphite in a mass ratio of 1:2. 2. the preparation method of flame-retardant plastic composite material according to claim 1, is characterized in that, The intrinsic viscosity of the PBT used is 0.75-0.95dl/g; the melt index MI of the ABS used is between 1-5g/10min. 3. the preparation method of flame-retardant plastic composite material according to claim 1, is characterized in that, The silicone oil used is dimethyl silicone oil with a viscosity of 1000-5000mPa·s. 4. the preparation method of flame-retardant plastic composite material according to claim 1, is characterized in that, The polytetrafluoroethylene used is in powder form with an average particle diameter of 3-8 μm. 5. the preparation method of flame-retardant plastic composite material according to claim 1, is characterized in that, The twin-screw extruder is an intermeshing parallel co-rotating twin-screw extruder; Among them, the aspect ratio of the screw is 36-44, the combination of the screw is a combination of medium shear rate, and the temperature of the twin-screw extrusion granulation is between 180-250°C.