CN110041636B - Halogen-free flame-retardant antistatic wood-plastic composite material and preparation method thereof - Google Patents

Abstract

The invention discloses a halogen-free flame-retardant antistatic wood-plastic composite material and a preparation method thereof, wherein the halogen-free flame-retardant antistatic wood-plastic composite material comprises the following components in parts by mass: 40-90 parts of polystyrene, 10-30 parts of wood powder, 10-50 parts of antistatic agent and 10-50 parts of flame-retardant system. The halogen-free flame-retardant antistatic wood-plastic composite material is prepared by a solution method, and the filler is pretreated by the coupling agent, so that the dispersion of the filler in the resin and the compatibility between the filler and a resin matrix are promoted; the magnetic metal powder is directionally arranged along the magnetic field direction by utilizing the action of the magnetic field, and a conductive path is easily formed in the molding process, so that the antistatic property of the wood-plastic composite material is improved, the dosage of the antistatic agent is reduced, and the production cost is effectively reduced.

Description

A halogen-free flame retardant and antistatic wood-plastic composite material and preparation method thereof

technical field

The invention relates to a wood-plastic composite material and a preparation method thereof, in particular to a halogen-free flame-retardant and antistatic wood-plastic composite material and a preparation method thereof.

Background technique

Wood Plastic Composite (WPC for short) is a new type of green and environmentally friendly material made of low-cost, natural wood, hemp and other natural fibers or powder materials and thermoplastics. It has high strength-to-weight ratio and impact resistance. capacity, good dimensional stability and machinability. At present, WPC is mainly used for doors and windows, floors, partitions, etc. in the construction field. Since wood-plastic composite materials are mainly composed of two kinds of flammable thermoplastics and wood fiber materials with good electrical insulation properties, they have fire hazards when used as building and decorative materials, and are prone to static electricity, especially when used in operating rooms, In important areas such as electronic device workshops, it is particularly important to carry out flame retardant and antistatic treatment. Therefore, it is of great significance to endow wood-plastic composites with new properties, expand their application range, and improve the added value of products through research on antistatic and flame-retardant wood-plastic composites.

分子筛为协效剂、1-10份硼酸锌为抑烟剂构成膨胀型阻燃剂，制得了阻燃性能较好的木塑复合材料，但是阻燃剂的添加量比较大，成本过高且木塑复合材料力学性能较差。类似的还有，申请号为201811091032.1的专利公布了一种阻燃聚乙烯木塑复合材料的制备方法。该专利所制备的木塑材料虽然阻燃效果较好，但其力学性能差。申请号为201710412564.X的专利公布了一种地热供暖用高导热阻燃聚氯乙烯木塑地板及其制备方法，所制备的木塑具有良好的导热防火性能，但是所使用的阻燃剂为八溴醚和磷酸三苯酯，水溶性差，燃烧时释放出有毒气体，且生产成本高，限制其使用范围。At present, the flame retardant properties of wood-plastic composite materials are often improved by adding flame retardants to wood-plastic composite materials. The patent with the application number of 200910072237.X discloses a method for preparing flame-retardant wood-plastic composite materials by using modified plastics. It uses 18-22 parts of melamine pyrophosphate or melamine polyphosphate as the main flame retardant, and 1- 8 parts starch as charring agent, 0.5-34 parts

Molecular sieve is a synergist, and 1-10 parts of zinc borate is a smoke suppressant to form an intumescent flame retardant, and a wood-plastic composite material with good flame retardant performance is obtained. However, the amount of flame retardant added is relatively large, and the cost is too high. The mechanical properties of wood-plastic composites are poor. Similarly, the patent with the application number of 201811091032.1 discloses a preparation method of a flame-retardant polyethylene wood-plastic composite material. Although the wood-plastic material prepared by this patent has good flame retardant effect, its mechanical properties are poor. The patent with the application number of 201710412564.X discloses a high thermal conductivity fire-retardant polyvinyl chloride wood-plastic floor for geothermal heating and a preparation method thereof. The prepared wood-plastic has good thermal conductivity and fire resistance, but the flame retardant used is Octabromo ether and triphenyl phosphate have poor water solubility, release toxic gases when burned, and have high production costs, which limit their scope of use.

There are many antistatic methods for polymer composite materials, and the ultimate purpose is to make polymer composite materials generate less electrostatic charge during use or to leak the generated electrostatic charge in time. Xu Fengjiao (Journal of Forestry Engineering, 2016, 1(5): 45-51) improved the antistatic properties of PVC wood-plastic composites by adding three different types of antistatic agents, and found that SAS-93 type antistatic agent was effective for PVC wood-plastic composites. The antistatic effect of composite materials is the best, but SAS-93 is very hygroscopic and difficult to store. The patent of application number 201610533566.X discloses an antistatic wheat straw polypropylene wood-plastic composite material and a preparation method thereof, the antistatic agent used is modified conductive carbon black (80 parts of conductive carbon black, 3 parts by weight of conductive carbon black, 3 1 part silane coupling agent and 200mL absolute ethanol were put into a three-necked flask, stirred at 60°C for 1.5h, after suction filtration, the filter cake was placed in an oven, dried at 105°C, pulverized and ground to obtain), The modified conductive carbon black is added to the wood-plastic composite material, and the obtained wood-plastic material has good antistatic performance, but the preparation process of the antistatic agent is complicated, and it is difficult to realize industrial production. Similarly, the patent with the application number of 201410723764.3 discloses a conductive/antistatic polyethylene wood-plastic composite material and a preparation method thereof. The conductive/antistatic wood-plastic composite material is prepared by adding highly conductive carbon nanotubes. The conductive and antistatic properties of the wood-plastic composite material can be used under different conditions, but the antistatic agent used is expensive, and the production cost of the antistatic wood-plastic material is high, which is not conducive to mass production.

SUMMARY OF THE INVENTION

In order to solve the problems of poor antistatic performance and easy burning of the existing wood-plastic composite material, the present invention provides a halogen-free flame-retardant and antistatic wood-plastic composite material and a preparation method thereof.

In order to make the wood-plastic composite material have better antistatic performance at a lower filling amount, the present invention prepares a halogen-free flame-retardant and antistatic wood-plastic composite material by a solution method, and uses the action of a magnetic field to make the originally randomly arranged magnetic metal powder along the The direction of the magnetic field is oriented, and it is easy to form a conductive path during the molding process of the composite material, so as to improve the antistatic performance of the wood-plastic composite material, while reducing the amount of antistatic agent and cost, and the technical route is convenient and antistatic effect. it is good.

The halogen-free flame retardant and antistatic wood-plastic composite material of the present invention comprises the following components by mass:

The polystyrene has a melt flow rate (MFR) of 0.5-8 g/10min.

The particle size of the wood flour is 40-80 mesh.

The antistatic agent is a magnetic filler such as iron powder (Fe), triiron tetroxide (Fe ₃ O ₄ ) or nickel powder (Ni), and the particle size of the magnetic filler is ≥100 mesh.

The flame retardant system includes a flame retardant and a synergist, wherein the flame retardant is ammonium polyphosphate with a degree of polymerization of 1000-4000, and the synergist is one of pentaerythritol, melamine, magnesium hydroxide, aluminum hydroxide, or the like. Several; the mass ratio of the flame retardant to the synergist is 1:2-4:1.

The preparation method of halogen-free flame retardant and antistatic wood-plastic composite material of the present invention comprises the following steps:

Step 1: Filler Pretreatment

Soak wood flour, magnetic filler, flame retardant and synergist in ethanol solution containing coupling agent, ultrasonically disperse for 0.5-1h, then stir in 40-60℃ water bath for 1.5-3h, filter and set aside;

Step 2: Matrix Pretreatment

Add polystyrene into chloroform, stir and disperse in a water bath at 50°C for 2-4h until completely dissolved;

Step 3: Filler and Matrix Mixing

Add the modified filler obtained in step 1 to the solution obtained in step 2, first stir at 50 °C for 3 hours, then heat up to 60-70 °C and stir for 1 hour, stop stirring when the solution is viscous;

Step 4: Magnetic Field Orientation Treatment

Pour the mixed solution obtained in step 3 into the mold, and apply a magnetic field to make the magnetic fillers regularly arranged along the magnetic field lines. Halogen flame retardant antistatic wood plastic composite material.

In step 1, the coupling agent is any one of a silane coupling agent, an aluminate coupling agent, a titanate coupling agent, and the like. The mass ratio of coupling agent to filler (wood flour, antistatic agent, flame retardant and synergist) used in filler pretreatment is 1:30-1:8.

In step 2, the mass-volume ratio of polystyrene to chloroform is 1 g: 3-10 mL.

In step 4, the mold is a non-metallic mold such as a glass mold or a ceramic mold.

In step 4, the magnetic field is an alternating magnetic field, the magnetic field strength is 30-150 Gs, and the processing time is 20-60 min.

The invention adopts "solution method" to mix the filler and the matrix resin, which is beneficial to promote the dispersion of the filler in the resin; the coupling agent is used to pretreat the filler to improve the compatibility between the filler and the resin matrix; Metal fillers are directionally distributed in the matrix, and it is easy to form a conductive path during the molding process of the composite material, so as to improve the antistatic performance of the composite material, reduce the amount of antistatic agent, reduce production costs, and the technical route is convenient, antistatic Works well.

Description of drawings

Fig. 1 is a scanning electron microscope photograph of the brittle fracture section of the prepared PS wood-plastic composite material along the orientation direction of the magnetic field. Above the dotted line is Example 1, and below the dotted line is Comparative Example 1.

FIG. 2 is a scanning electron microscope photograph of the brittle fracture section of the prepared PS wood-plastic composite material along the magnetic field orientation direction. Above the dotted line is Example 2, and below the dotted line is Comparative Example 2.

Detailed ways

The technical solution of the present invention will be further described below in conjunction with specific embodiments, but the scope of the present invention is not limited by these embodiments.

Example 1:

1. Ingredients

PS plastic 75g, wood powder 25g, Fe powder 20g, APP 20g, Mg(OH) ₂ 5g.

2. Preparation

1) First soak wood powder, Fe powder, APP and Mg(OH) ₂ in an ethanol solution containing 5 g of silane coupling agent, ultrasonically disperse for 1 hour, stir and disperse in a 50°C water bath for 2 hours, and filter to obtain Mixture A, which is for later use ;

2) Add PS plastic to chloroform solution, stir and disperse at 50°C for 3h;

3) After the PS is completely dissolved, the mixture A is added to the chloroform dissolved with PS, first stirred at 50°C for 3 hours, then heated to 65°C and stirred for 1 hour until the solution is viscous, stop stirring;

4) Pour the above solution into a glass mold, and apply a magnetic field of 100Gs for 30min, so that the Fe powder is regularly arranged along the magnetic field lines. After the mixture is cooled and solidified, it is dried and defoamed in a 70°C oven for 24h. Afterwards, the halogen-free flame retardant and antistatic wood-plastic composite material can be prepared.

Comparative Example 1:

1. Ingredients

PS plastic 75g, wood powder 25g, Fe powder 20g, APP 20g, Mg(OH) ₂ 5g.

2. Preparation

1) First soak wood powder, Fe powder, APP and Mg(OH) ₂ in an ethanol solution containing 5 g of silane coupling agent, ultrasonically disperse for 1 hour, stir and disperse at 50°C for 2 hours, and filter to obtain mixture A, which is for later use;

2) Add PS plastic to chloroform solution, stir and disperse at 50°C for 3h;

3) After the PS is completely dissolved, the mixture A is added to the chloroform dissolved with PS, first stirred at 50°C for 3 hours, then heated to 65°C and stirred for 1 hour until the solution is viscous, stop stirring;

4) Pour the above solution into a glass mold, after cooling and solidifying, drying and defoaming in an oven at 70°C for 24 hours, the halogen-free flame retardant and antistatic wood-plastic composite material can be obtained.

Example 2:

1. Ingredients

PS plastic 75g, wood powder 25g, Fe powder 30g, APP 10g, Mg(OH) ₂ 5g.

2. Preparation

1) First soak wood powder, Fe powder, APP and Mg(OH) ₂ in an ethanol solution containing 5 g of silane coupling agent, ultrasonically disperse for 1 hour, stir and disperse at 50°C for 2 hours, and filter to obtain mixture A, which is for later use;

2) Add PS plastic to chloroform solution, stir and disperse at 50°C for 3h;

3) After the PS is completely dissolved, the mixture A is added to the chloroform dissolved with PS, first stirred at 50°C for 3 hours, then heated to 65°C and stirred for 1 hour until the solution is viscous, stop stirring;

4) Pour the above solution into a glass mold, and apply a magnetic field of 100Gs for 30min, so that the Fe powder is regularly arranged along the magnetic field lines. After the mixture is cooled and solidified, it is dried and defoamed in a 70°C oven for 24h. Afterwards, the halogen-free flame retardant and antistatic wood-plastic composite material can be prepared.

Comparative Example 2:

1. Ingredients

PS plastic 75g, wood powder 25g, Fe powder 30g, APP 10g, Mg(OH) ₂ 5g.

2. Preparation

1) First soak wood powder, Fe powder, APP and Mg(OH) ₂ in an ethanol solution containing 5 g of silane coupling agent, ultrasonically disperse for 1 hour, stir and disperse at 50°C for 2 hours, and filter to obtain mixture A, which is for later use;

2) Add PS plastic to chloroform solution, stir and disperse at 50°C for 3h;

3) After the PS is completely dissolved, the mixture A is added to the chloroform dissolved with PS, first stirred at 50°C for 3 hours, then heated to 65°C and stirred for 1 hour until the solution is viscous, stop stirring;

4) Pour the above solution into a glass mold, after cooling and solidifying, drying and defoaming in an oven at 70°C for 24 hours, the halogen-free flame retardant and antistatic wood-plastic composite material can be obtained.

The composite materials prepared by the examples and comparative examples were tested for antistatic properties, mechanical properties, and combustion properties, and the test results were as follows:

Table 1. Physical properties test data table of PS wood-plastic composites

sample number Volume resistivity (Ω·m) Notched impact strength (kJ/m²) Example 1 1.58E+09 3.38 Comparative Example 1 2.57E+09 3.44 Example 2 1.06E+09 3.59 Comparative Example 2 2.14E+09 3.69

Note: Volume resistivity is tested according to GB/T 1410-2006 standard; Notched impact strength is tested according to GB/T 1043.1-2008 standard.

Table 2. PS wood-plastic composite material combustion performance test data table

sample number Example 1 Comparative Example 1 Example 2 Comparative Example 2 Ignition time (s) 54 54 52 51 Total heat release (MJ m^-2) 89.2 83.2 86.1 88.3 Peak heat release rate (kW m^-2) 334.8 339.5 342.9 346.6 Average heat release rate (kW m^-2) 127.2 141.5 149.5 167.8 Fire index (kW m^-2 s^-1) 3.21 3.39 3.52 3.32 Mass loss rate (%) 0.037 0.041 0.042 0.045 Smoke production (m²) 7.33 26.5 7.08 17.6 CO gas production (m²) 0.001 0.004 0.002 0.002 CO₂ gas production (m²) 0.01 0.03 0.25 0.38 Residual carbon rate (wt%) 19.7 22.1 14.1 16.7 Oxygen Index(%) 35 33 28 26 UL-94 rating V-0 V-0 V-1 V-1

Note: Cone calorimeter test is performed according to ASTM E1354, ISO 5560 standard; oxygen index test is performed according to GB/T2406.2-2009 standard; UL-94 test is performed according to GB/T 2408-2008 standard.

It can be seen from Table 1 that the volume resistivity of the samples after magnetic field orientation treatment (Examples 1 and 2) has different degrees of change compared with the samples without magnetic field orientation treatment (Comparative Examples 1 and 2). This shows that after the magnetic field orientation, the iron powder is oriented in the direction of the magnetic field line in the wood-plastic composite material, which is conducive to the formation of a conductive network and significantly improves the antistatic performance of the wood-plastic composite material. Figures 1 and 2 show the scanning electron microscope pictures of the brittle fracture section of the prepared PS wood-plastic composite material after being frozen in liquid nitrogen along the orientation direction of the magnetic field. It is not difficult to see that the samples without magnetic field orientation are randomly distributed in the resin matrix, and the Fe powder particles are blocked by the wood powder and the PS matrix, and cannot contact each other to form an effective conductive network. After the action of the magnetic field, the Fe powders are rearranged, and the Fe powders are aligned along the direction of the magnetic field, the probability of mutual contact is increased, and an effective conductive network is easily formed, which improves the antistatic performance of the composite material. In addition, the impact strength of Examples 1 and 2 and Comparative Examples 1 and 2 did not change significantly. It can be seen that the magnetic field orientation can improve the antistatic properties of wood-plastic composites without significantly reducing the mechanical properties of wood-plastic composites. The results of the combustion performance test data in Table 2 show that the halogen-free flame retardant and antistatic wood-plastic composite material obtained by this implementation method has good flame retardant properties.

To sum up, the present invention can significantly improve the flame retardant performance and antistatic performance of the wood-plastic composite material under the premise of ensuring good mechanical properties, and the technical route is convenient and suitable for industrial production.

The above is only an exemplary description of the present invention. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacements that those skilled in the art can do without creative effort are all within the scope of the present invention. scope of protection.

Claims (2)

1. The preparation method of the halogen-free flame-retardant antistatic wood-plastic composite material is characterized by comprising the following steps of:

step 1: pretreatment of

Soaking wood powder, magnetic filler, flame retardant and synergist in ethanol solution containing coupling agent, ultrasonically dispersing for 0.5-1h, stirring in water bath at 40-60 deg.C for 1.5-3h, and filtering;

step 2: substrate pretreatment

Adding polystyrene into trichloromethane, stirring and dispersing in a water bath at 50 ℃ for 2-4h until the polystyrene is completely dissolved;

and step 3: mixing

Adding the raw material obtained after the pretreatment in the step (1) into the solution obtained in the step (2), firstly stirring for 3h at 50 ℃, then heating to 60-70 ℃, stirring for 1h, and stopping stirring when the solution is viscous;

and 4, step 4: magnetic field orientation treatment

Pouring the mixed solution obtained in the step (3) into a mold, applying a magnetic field to ensure that the magnetic fillers are regularly arranged along the magnetic field lines, and drying and defoaming the mixture in an oven at the temperature of 50-80 ℃ for 24-48h after the mixture is cooled and solidified to obtain the halogen-free flame-retardant antistatic wood-plastic composite material;

the halogen-free flame-retardant antistatic wood-plastic composite material comprises the following components in parts by mass:

40-90 parts of polystyrene

10-30 parts of wood powder

10-50 parts of magnetic filler

10-50 parts of a flame-retardant system;

the melt flow rate of the polystyrene is 0.5-8g/10 min;

the grain size of the wood powder is 40-80 meshes;

the magnetic filler is iron powder, ferroferric oxide or nickel powder, and the particle size of the magnetic filler is more than or equal to 100 meshes;

the flame retardant system comprises a flame retardant and a synergist, the mass ratio of the flame retardant to the synergist is 1:2-4:1, wherein the flame retardant is ammonium polyphosphate with polymerization degree of 1000-4000, and the synergist is one or more of pentaerythritol, melamine, magnesium hydroxide and aluminum hydroxide;

in the step 1, the coupling agent is any one of silane coupling agent, aluminate coupling agent and titanate coupling agent; the ratio of the coupling agent to the wood powder to the magnetic filler to the flame retardant to the synergist is 1:30-1: 8;

in the step 2, the mass volume ratio of the polystyrene to the trichloromethane is 1g:3-10 mL;

in the step 4, the magnetic field is an alternating magnetic field, the magnetic field intensity is 30-150 Gs, and the processing time is 20-60 min.

2. The method of claim 1, wherein:

in step 4, the mold is a glass mold or a ceramic mold.

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