CN116927025A - A kind of paving mat prepared from polyethylene composition - Google Patents

Abstract

The invention discloses a paving pad prepared from a polyethylene composition. The paving pad includes a pad body and L-shaped first and second pad connecting parts, so that multiple pads can be aligned along the plane direction. When spliced, a large and flat paving pad can be formed; the polyethylene composition used to prepare the pad includes 100 parts of polyethylene, 5-10 parts of compatibilizer, 25-45 parts of flame retardant, 8-12 parts of antistatic agent, 0.15-0.25 parts of antioxidants and 0.3-0.5 parts of processing aids; wherein, the flame retardant is composed of nano-magnesium hydroxide and red phosphorus with a mass ratio of 2:1-1:2; wherein, the polyethylene The component consists of 70-95 parts of high-density polyethylene and 5-30 parts of linear low-density polyethylene. The paving pad of the present invention not only has good flame retardant and antistatic properties, but also has good mechanical properties.

Description

A kind of paving mat prepared from polyethylene composition

Technical field

The present invention relates to a paving pad prepared from polymer materials, and in particular to a paving pad prepared from a polyethylene composition, which can be used as a coal mine paving plate.

Background technique

The road surface of mining tunnels has been crushed by heavy-duty vehicles for a long time, and the concrete slabs in some sections have broken, causing pits, subsidence, slurry and other diseases, making transport vehicles impassable and seriously affecting production, requiring large-scale paving pads. Concrete pads have poor toughness and impact resistance, and low laying efficiency; large steel plates are dense, inconvenient to handle, and prone to corrosion and rust; although fiberglass plates have good rigidity and low density, they have low bearing capacity and aging resistance. Poor and low service life; although the wooden backing board has low density, it is small in size, has low bearing capacity and is flammable. None of the above materials can fully meet the requirements for heavy-duty vehicle transportation.

CN103881206B discloses a flame-retardant polymer plastic and a coal mine tunnel pad made of it, including 1) polyethylene resin, compound flame retardant (decabromodiphenylethane and antimony trioxide), and antioxidant , lubricant, and carbon black are mixed in proportion and granulated through a twin-screw extruder; 2) Put the above pellets into an injection molding machine, match the mold of the tunnel pad, and perform injection molding; 3) The tunnel pad includes a base plate and a The hoarding is fixed on the base plate, and the backing plate is connected through a metal connection card. After the laying is completed, the cavity is filled with pulverized coal. However, due to the use of brominated antimony-containing flame retardants, they produce toxic fumes containing toxic and carcinogenic polybrominated diphenzodiones (PBDE) and polybrominated dibenzofurans (PBDF) when burned. The closed environment of coal mines can easily cause "secondary disasters".

When used underground in coal mines, paving slabs need to carry a variety of mining equipment, so they need to have good mechanical properties. At the same time, taking into account the safety production requirements of coal mines, they must also put forward high requirements for flame retardant and antistatic properties, which means It is necessary to add higher amounts of flame retardants and antistatic agents. However, the addition of these additives will in turn affect the mechanical properties of the board. Therefore, how to obtain paving slabs for underground coal mines with excellent mechanical properties while ensuring safe production in coal mines is also an important research and development direction in this field in the future.

The inventor of the present invention unexpectedly discovered that polyethylene is a general-purpose polymer material with the advantages of good rigidity, easy processing, and corrosion resistance. It is expected to be used to prepare movable paving pads. However, due to its structure, it is flammable and prone to accumulation. Static electricity, not suitable for underground application environment. Based on this, the inventor of the present invention adopts the polyethylene composition of the present invention and introduces a phosphorus-based flame retardant and a carbon black antistatic agent into the polyethylene resin system to meet the flame retardant and antistatic properties; introduces modified nano-hydroxide Magnesium material is used as a modifier to improve the flame retardant properties of the material while maintaining the mechanical properties of the material; choosing a compatibilizer with dual functional components of toughening and coupling can well disperse fillers such as flame retardants and improve impact performance; and, the prepared polyethylene sheet material can have the dual functions of flame retardant and antistatic, maintain high mechanical properties, and improve the heat resistance.

Contents of the invention

The object of the present invention is to provide a paving pad prepared from a polyethylene composition, which can be spliced to form a large-area paving board, which not only has good flame retardant and antistatic properties, but also has good mechanical properties.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A paving pad prepared from a polyethylene composition. The paving pad includes a pad main body in a rectangular flat structure. The top and/or lower surface of the pad main body is provided with pad anti-skid patterns. An L-shaped first pad connecting portion protruding from the pad body extends from two adjacent edges of the lower surface of the pad body along the plane direction, and two adjacent edges of the upper surface of the pad body extend An L-shaped second pad connecting portion protruding from the pad body extends in the plane direction;

The first pad connection part and the second pad connection part together form a rectangle of the pad body, and the sum of the thicknesses of the first pad connection part and the second pad connection part is equal to the pad body. The thickness of the main body of the board enables a large and flat paving pad to be formed when multiple pads are spliced in the plane direction;

The polyethylene composition includes the following components by weight:

Wherein, the flame retardant is composed of nano-magnesium hydroxide and red phosphorus with a mass ratio of 2:1-1:2; for example, the mass ratios of nano-magnesium hydroxide and red phosphorus are 1.8:1, 1:1, 1: 1.2, 1:1.4 or 1:1.8; preferably 1.5:1-1:1.5;

Wherein, the polyethylene component is composed of 70-95 parts, such as 75, 80, 85 or 90 parts, of high-density polyethylene and 5-30 parts, such as 8, 10, 20 or 25 parts, of linear low-density polyethylene.

According to the paving pad of the present invention, in one embodiment, in order to facilitate the splicing and fixing between pads, the two sides of the L-shaped first pad connecting portion and the L-shaped second pad are At least two connecting holes are respectively provided on the two sides of the connecting portion, so that the two adjacent pads can be fixed through the connecting piece through the at least two connecting holes on each side during splicing. The specific structure of such connectors for connection is well known in the art, such as connectors composed of bolts and nuts. It can be understood in the art that for underground safety, the connecting piece can be made of the same material as the backing plate or other flame-retardant and antistatic materials; in one embodiment, in order to facilitate disassembly, the connecting piece is made of a spring washer and a connecting piece. It consists of a main body, wherein one end of the main body of the connecting piece adjacent to the spring washer is in the shape of a cylinder with an enlarged diameter, and the other end is in the shape of a long handle convenient for a knob, and the connecting hole is set in a rectangular shape matching the shape of the long handle, After the main body of the connecting piece is rotated 90 degrees through the connecting hole, it can be locked without falling off with the cooperation of the spring washer, thereby facilitating disassembly.

According to the paving pad of the present invention, in one embodiment, in order to further improve the polyethylene composition of the present invention for underground coal mine applications, the melt index of the high-density polyethylene under the conditions of 190°C and 2.16kg is 2- 10g/min, preferably 5-10g/min, more preferably 7-9g/min;

The melt index of the linear low-density polyethylene under the conditions of 190°C and 2.16kg is 2-10g/min, preferably 2-5g/min, and more preferably 2-4g/min.

According to the paving mat of the present invention, preferably, the aspect ratio of the nano-magnesium hydroxide is 8/1-10/1, and the long axis direction is 80-100nm;

According to the paving pad of the present invention, preferably, the nano-magnesium hydroxide is modified nano-magnesium hydroxide. The modification method of nano-magnesium hydroxide can be found in CN104592554A. The specific preparation method is as follows: based on the total weight of raw materials, 70-80% such as 75% nano magnesium hydroxide, 15-25% such as 20% aluminate, and 2-5% dimethyl maleate are mixed and stirred evenly to prepare modified nano hydrogen Magnesium oxide.

According to the paving mat of the present invention, preferably, the compatibilizer is polyethylene grafted maleic anhydride (PE-g-MAH), polyolefin elastomer grafted maleic anhydride (POE-g-MAH), One or more types of ethylene propylene rubber grafted with maleic anhydride (EPDM-g-MAH);

The antistatic agent is one or more of conductive carbon black, graphite and carbon nanotubes.

According to the paving pad of the present invention, preferably, the processing aid is a compound of PE wax and one or more of stearic acid, zinc stearate, and calcium stearate;

The antioxidant is tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol, 1,3,5-trimethyl-2,4,6-(3 , one or more of 5-di-tert-butyl-4-hydroxybenzyl)benzene, tris[2,4-di-tert-butylphenyl]phosphite and distearyl thiodipropionate .

According to the paving pad of the present invention, preferably, when the polyethylene composition is molded into a pad, its limiting oxygen index is 30-35, the surface resistance is 10 ⁶ -10 ⁸ Ω, the bending strength is ≥ 15 MPa, and the fracture The elongation is ≥100%, and the notched impact strength is 12-18kJ/m ² .

In the present invention, the polyethylene composition used can be prepared by the following method:

(1) Weigh red phosphorus, antistatic agents, antioxidants, processing aids and part of the high-density polyethylene according to the weight ratio and initially mix them, then add them to the extruder hopper for melt blending and granulation to obtain Double anti-bacterial masterbatch;

(2) Melt and blend the obtained double-resistant masterbatch, remaining high-density polyethylene, linear low-density polyethylene, compatibilizer, and nano-magnesium hydroxide to obtain the flame-retardant and antistatic polyethylene composition of the present invention, which After corresponding molding processing, the paving pad can be obtained.

The polyethylene composition according to the present invention is, preferably, the extruder described in step (1) adopts a reciprocating single-screw extruder; the melt blending process in step (2) is in a twin-screw extruder. The operating temperature range of the melt blending process is 135-190°C.

For the polyethylene composition according to the present invention, preferably, the dosage ratio of high-density polyethylene in step (1) and step (2) is 1: (1.55-2.5), such as 1:1.8, 1:2 or 1:2.3.

The object of the present invention is to provide a coal mine tunnel paving plate and a preparation method thereof.

(1) In the polyethylene system used in the paving mat of the present invention, it was unexpectedly found that the specific proportion of red phosphorus and special modified nano-magnesium hydroxide of the present invention were introduced as flame retardants to improve the flame retardant properties of the material. Maintain the thermal stability and mechanical properties of the material; limiting the size of the nano-magnesium hydroxide to within the aforementioned range not only improves the flame retardant effect of the modified magnesium hydroxide, but also reduces the impact on the tensile properties of the matrix resin.

(2) The present invention selects a compatibilizer with both toughening and coupling dual-functional components and uses compound processing aids to disperse the flame retardant well and improve product performance.

(3) The backing plate made by the present invention can meet the requirements for use in coal mines and can maintain various properties in a balanced manner: limiting oxygen index 30-35, surface resistance 10 ⁶ -10 ⁸ Ω, bending strength ≥ 15MPa, bending modulus ≥800MPa, elongation at break ≥100%, notched impact strength 12-18kJ/m2.

Description of the drawings

Figure 1 is a schematic diagram of an embodiment of the backing plate of the present invention;

Figure 2 is a schematic diagram of an embodiment of a connector;

Figure 3 is a schematic diagram of an embodiment after the backing plates are connected;

Among them, 1 is the backing plate main body; 2 is the backing plate anti-slip pattern; 3 is the lower surface of the backing plate main body; 31 is the first backing plate connection part; 4 is the upper surface of the backing plate main body; 41 is the second backing plate connection part; 5 is the connection hole; 6 is the main body of the connector; 7 is the spring washer.

Detailed ways

The present invention will be further described below in conjunction with the embodiments and drawings, but the present invention is not limited to the listed embodiments.

As shown in Figure 1, in one embodiment, the paving pad of the present invention includes a pad body 1 in a rectangular flat structure, and the pad body 1 is provided with pad anti-slip on the upper surface and/or lower surface. Pattern 2, an L-shaped first pad connecting portion 31 protruding from the pad body 1 extends from two adjacent edges of the lower surface 3 of the pad body 1 along the plane direction. An L-shaped second pad connecting portion 41 protruding from the pad body extends from two adjacent edges of the upper surface 4 along the plane direction.

The first pad connecting part 31 and the second pad connecting part 41 together form a rectangle of the pad body 1 , and the thickness of the first pad connecting part 31 and the second pad connecting part 41 is and is equal to the thickness of the pad body 1, so that when multiple pads are spliced in the plane direction, a large and flat paving pad can be formed (as shown in Figure 3);

At least two connection holes 5 are respectively provided on two sides of the L-shaped first pad connecting part 31 and on two sides of the L-shaped second pad connecting part 41, so that they can pass through during splicing. At least two connecting holes on each side are used to fix two adjacent pads through connecting pieces. In one embodiment, as shown in Figure 2, the connector is composed of a spring washer 7 and a connector body 6, wherein one end of the connector body 6 adjacent to the spring washer 7 is in the shape of a cylinder with an enlarged diameter, and the other end is in the shape of a cylinder with an enlarged diameter. It is in the shape of a long handle that is convenient for knobs. At the same time, the connecting hole 5 is set in a rectangular shape matching the long handle shape, so that the main body 6 of the connecting piece passes through the connecting hole and rotates 90 degrees to be able to rotate 90 degrees with the cooperation of the spring washer 7 Locks in place, making removal easy.

The polyethylene composition used in the paving mat of the present invention will be further described below with reference to examples/comparative examples.

In the following examples and comparative examples, the selected antioxidants are Irganox 1010 and Irgafos 168, and the ratio is 1:1; the selected compatibilizer is polyolefin elastomer grafted maleic anhydride, with the brand name GR216; the selected high The density polyethylene is DMDA-8007, with a melt index of 7-9g/min (190°C, 2.16kg); the selected linear low-density polyethylene is DFDA-7042, with a melt index of 2-4g/min (190 ℃, 2.16kg); the selected processing aids are PE wax and zinc stearate, the mass ratio is 2:1; the antistatic agent is conductive carbon black, brand F900;

Nano-magnesium hydroxide is homemade in the laboratory, see CN104592554A:

Based on the total weight of raw materials, mix 75% nano magnesium hydroxide, 20% aluminate, and 5% dimethyl maleate and stir evenly. The stirring speed is 200-400 rpm. The stirring time 30-45min, the modified nanometer magnesium hydroxide is obtained.

The aspect ratio of the nanomagnesium hydroxide is 8/1-10/1, and the long axis direction is 80-100nm.

In the following examples and comparative examples, the material preparation and testing methods involved are as follows:

Prepare dual-antibacterial masterbatch according to the following raw material proportions:

Mix 4.35kg high-density polyethylene DMDA-8007, 3kg red phosphorus, 2.4kg conductive carbon black, 100g antioxidant, 100g PE wax, and 50g zinc stearate with a high-speed mixer for 3 minutes, and then mix with a low-shear Single-screw extruder melts, blends and granulates to prepare dual-resistant masterbatch. The screw length-to-diameter ratio of the single-screw extruder is 15/1, the screw speed is 100 rpm, and the screw extrusion blending temperature is 180°C.

Test Methods:

(1) Notched impact strength test method

Take the weighed composition pellets and press them into tablets with a 100mm×120mm×4mm mold to make samples, and cut out a 10mm×80mm×4mm sample. Make a 2mm deep notch in the middle of the sample, and then place it in the test room for 24 hours. The CEAST impact testing machine was used for testing according to the GB1843-2008 method.

(2)Bending strength test method

Take the weighed composition pellets and press them into tablets with a 100mm×120mm×4mm mold, and cut out a 10mm×80mm×4mm sample. Then, after placing it in the test room for 24 hours, use the Instron5965 testing machine to test according to the GB9341-2008 method. The maximum bending stress endured by the specimen during bending is the bending strength of the composite material.

(3) Test method for elongation at break

Take the weighed composition pellets and press them into tablets with a 100mm×120mm×4mm mold. Cut dumbbell-shaped samples according to the requirements of GB/T1040.2-2006. Then, after placing them in the test room for 24 hours, use the Instron5965 testing machine according to GB /T1040.2-2006 method for testing, and the strain change value at break is the elongation at break of the composition material.

(4)Surface resistivity test method

According to GB/T 1410-2006 test, each sample is tested at 5 points, 3 times in parallel, and the average value is taken.

(5)Limiting oxygen index test method

Tested according to GB/T 2406.2-2009, the sample thickness is 4.0mm.

(6) Test method for carbon residue rate at 600℃

Thermogravimetric analysis test (TGA): Put the sample into the crucible, raise the temperature from room temperature to 600°C at 10°C/min under nitrogen atmosphere, and keep it warm for 30 minutes.

Example 1

Weigh 5kg of double-antibacterial masterbatch, 3.4kg of high-density polyethylene DMDA-8007, 0.3kg of linear low-density polyethylene DFDA-7042, 1kg of nano-magnesium hydroxide, and 300g of GR216, and add them to a high-speed mixer. Add them to a high-speed mixer and stir for 3 seconds. minutes to mix evenly, and then use a low-shear twin-screw extruder to melt, blend, and granulate to prepare a flame-retardant and antistatic polyethylene composition. The screw length-to-diameter ratio of the twin-screw extruder is 26/1, the screw speed is 100 rpm, and the screw extrusion blending temperature is 170°C. Test samples were prepared by molding. The notched impact strength, flexural modulus, flexural strength, elongation at break, surface resistivity, and flame retardant performance test results of the flame-retardant and antistatic polyethylene composition obtained in Example 1 are shown in Table 1.

Example 2 Weigh 3.5kg double-antibacterial masterbatch, 3.8kg high-density polyethylene DMDA-8007, 1.2kg linear low-density polyethylene DFDA-7042, 1kg nano-magnesium hydroxide, and 500g GR216, and add them to a high-speed mixer. Within, stir for 3 minutes until the mixture is uniform, and then use a low-shear twin-screw extruder to melt, blend, and granulate to prepare a flame-retardant and antistatic polyethylene composition. The screw length-to-diameter ratio of the twin-screw extruder is 26/1, the screw speed is 150 rpm, and the screw extrusion blending temperature is 170°C. Test samples were prepared by molding. The notched impact strength, flexural modulus, flexural strength, elongation at break, surface resistivity, and flame retardant performance test results of the flame-retardant and antistatic polyethylene composition obtained in Example 2 are shown in Table 1.

Example 3 Weigh 3.5kg double-anti-bacterial masterbatch, 3.6kg high-density polyethylene DMDA-8007, 1.9kg linear low-density polyethylene DFDA-7042, 1.2kg nano-magnesium hydroxide, and 500g GR216, and add them to a high-speed mixer. In the mixer, stir for 3 minutes until the mixture is uniform, and then use a low-shear twin-screw extruder to melt, blend, and granulate to prepare a flame-retardant and antistatic polyethylene composition. The screw length-to-diameter ratio of the twin-screw extruder is 26/1, the screw speed is 200 rpm, and the screw extrusion blending temperature is 170°C. Test samples were prepared by molding. The notched impact strength, flexural modulus, flexural strength, elongation at break, surface resistivity, and flame retardant performance test results of the flame-retardant and antistatic polyethylene composition obtained in Example 3 are shown in Table 1.

Example 4

Weigh 3.5kg double-antibacterial masterbatch, 3.4kg high-density polyethylene DMDA-8007, 1.0kg linear low-density polyethylene DFDA-7042, 1.5kg nano-magnesium hydroxide, and 600g GR216, and add them to a high-speed mixer. Stir for 3 minutes until the mixture is uniform, and then use a low-shear twin-screw extruder to melt, blend, and granulate to prepare a flame-retardant and antistatic polyethylene composition. The screw length-to-diameter ratio of the twin-screw extruder is 26/1, the screw speed is 250 rpm, and the screw extrusion blending temperature is 170°C. Test samples were prepared by molding. The notched impact strength, flexural modulus, flexural strength, elongation at break, surface resistivity, and flame retardant performance test results of the flame-retardant and antistatic polyethylene composition obtained in Example 4 are shown in Table 1.

Table 1 Embodiment performance test table

Comparative example 1

Weigh 3.5kg of dual-resistant masterbatch, 4.1kg of high-density polyethylene DMDA-8007, 1.4kg of linear low-density polyethylene DFDA-7042, and 1kg of modified nanomagnesium hydroxide, and add them to a high-speed mixer. Add them to a high-speed mixer and stir for 3 seconds. minutes to mix evenly, and then use a low-shear twin-screw extruder to melt, blend, and granulate to prepare a flame-retardant and antistatic polyethylene composition. The screw length-to-diameter ratio of the twin-screw extruder is 26/1, the screw speed is 100 rpm, and the screw extrusion blending temperature is 140°C. Test samples were prepared by molding. The notched impact strength, flexural modulus, flexural strength, elongation at break, surface resistivity, and flame retardant performance test results of the flame-retardant and antistatic polyethylene composition obtained in Comparative Example 1 are shown in Table 2.

Comparative example 2

Weigh 3.5kg of dual-resistant masterbatch, 4.5kg of high-density polyethylene DMDA-8007, 1.0kg of linear low-density polyethylene DFDA-7042, and 1.0kg of GR216, add them to a high-speed mixer, and stir for 3 minutes until evenly mixed. , and then melt-blended and granulated through a low-shear twin-screw extruder to prepare a flame-retardant and antistatic polyethylene composition. The screw length-to-diameter ratio of the twin-screw extruder is 26/1, the screw speed is 100 rpm, and the screw extrusion blending temperature is 140°C. Test samples were prepared by molding. The notched impact strength, flexural modulus, flexural strength, elongation at break, surface resistivity, and flame retardant performance test results of the flame-retardant and antistatic polyethylene composition obtained in Comparative Example 2 are shown in Table 2.

Comparative Example 3 Weigh 3.5kg double-anti-bacterial masterbatch, 3.8kg high-density polyethylene DMDA-8007, 1.2kg linear low-density polyethylene DFDA-7042, 1kg nano-magnesium hydroxide (unmodified), and 500g GR216, and add them to a high-speed mixer , add into a high-speed mixer, stir for 3 minutes until mixed evenly, and then melt, blend, and granulate through a low-shear twin-screw extruder to prepare a flame-retardant and antistatic polyethylene composition. The screw length-to-diameter ratio of the twin-screw extruder is 26/1, the screw speed is 100 rpm, and the screw extrusion blending temperature is 140°C. Test samples were prepared by molding. The notched impact strength, flexural modulus, flexural strength, elongation at break, surface resistivity, and flame retardant performance test results of the flame-retardant and antistatic polyethylene composition obtained in Comparative Example 3 are shown in Table 2.

Comparative example 4

Weigh 3.5kg double-antibacterial masterbatch, 3.2kg high-density polyethylene DMDA-8007, 1.1kg linear low-density polyethylene DFDA-7042, 1.7kg modified nano-magnesium hydroxide, and 500g GR216, and add them to a high-speed mixer. Within, stir for 3 minutes until the mixture is uniform, and then use a low-shear twin-screw extruder to melt, blend, and granulate to prepare a flame-retardant and antistatic polyethylene composition. The screw length-to-diameter ratio of the twin-screw extruder is 26/1, the screw speed is 100 rpm, and the screw extrusion blending temperature is 140°C. Test samples were prepared by molding. The notched impact strength, flexural modulus, flexural strength, elongation at break, surface resistivity, and flame retardant performance test results of the flame-retardant and antistatic polyethylene composition obtained in Comparative Example 4 are shown in Table 2.

Comparative example 5

The difference from Example 1 is that the mass ratio of red phosphorus and modified nano-magnesium hydroxide in the flame retardant is 1:4, and the rest are the same.

Comparative example 6

The difference from Example 1 is that the size of the modified nanomagnesium hydroxide used in the flame retardant is an aspect ratio of 4/1-8/1, a length of 50-70nm, and the rest are the same.

Table 2 Comparative performance test table

According to Table 1 and Table 2, it can be concluded that compared with Comparative Examples 1-6, the polyethylene materials prepared in Examples 1-4 can have better mechanical, flame retardant and antistatic properties at the same time.

Since Comparative Example 1 does not contain a compatibilizer, fillers such as red phosphorus are not well dispersed and defects are easily formed, so the notch impact and elongation at break are low and the effect is not good.

Since Comparative Example 2 does not contain nano-magnesium hydroxide, it cannot form a synergistic flame retardant effect with red phosphorus, and the flame retardant performance is poor, so the effect is not good.

Comparative Example 3 uses unmodified nano-magnesium hydroxide. Due to the large particle size of the material, defects are easily formed at the interface with polyethylene. The notch impact and elongation at break are low, and the effect is not good.

In Comparative Example 4, because the content of nano-magnesium hydroxide is too high, it is easy to form agglomerations in the composition, resulting in poor dispersion with polyethylene and formation of defects. Therefore, the notch impact and elongation at break are low and the effect is not good.

In Comparative Example 5, because the red phosphorus content in the ratio of fixed red phosphorus and nano-magnesium hydroxide synergistic flame retardant is too low, the flame retardant performance is poor and the effect is not good.

Comparative Example 6: Since the aspect ratio of nano-magnesium hydroxide is closer to a spherical shape, it cannot exert the "fence effect" of flaky nano-magnesium hydroxide (dehydration forms a masking magnesium oxide film at low addition amounts), resulting in a deviation in the limiting oxygen index. Low, the mechanical properties also become poor, and the effect is not good.

Claims (10)

1. The paving base plate prepared from the polyethylene composition comprises a base plate main body with a rectangular plate structure, wherein the upper surface and/or the lower surface of the base plate main body is provided with base plate anti-skid patterns, two adjacent edges of the lower surface of the base plate main body extend in the plane direction to form a first base plate connecting part protruding out of the base plate main body in an L shape, and two adjacent edges of the upper surface of the base plate main body extend in the plane direction to form a second base plate connecting part protruding out of the base plate main body in an L shape;

the first pad connecting part and the second pad connecting part together enclose a rectangle of the pad main body, and the sum of the thicknesses of the first pad connecting part and the second pad connecting part is equal to the thickness of the pad main body, so that a large and flat paving pad can be formed when a plurality of pads are spliced along the plane direction;

the polyethylene composition comprises the following components in parts by weight:

wherein the flame retardant consists of nano magnesium hydroxide and red phosphorus in a mass ratio of 2:1-1:2;

wherein the polyethylene component consists of 70-95 parts of high-density polyethylene and 5-30 parts of linear low-density polyethylene.

2. The paving mat as claimed in claim 1, wherein the two sides of the L-shaped first mat connecting portion and the two sides of the L-shaped second mat connecting portion are respectively provided with at least two connecting holes, such that two adjacent mats can be fixed via the connecting member through the at least two connecting holes on each side when being spliced;

preferably, the connecting piece comprises a spring washer and a connecting piece main body penetrating through the spring washer, wherein one end, close to the spring washer, of the connecting piece main body is cylindrical with an enlarged diameter, the other end is long-handled and convenient for a knob, and meanwhile, the connecting hole is rectangular matched with the long-handled, so that the connecting piece main body can be locked and not fall off under the matching of the spring washer after penetrating through the connecting hole and rotating for 90 degrees.

3. Paving mat according to claim 1 or 2, characterized in that the high density polyethylene has a melt index of 2-10g/min, preferably 5-10g/min, more preferably 7-9g/min at 190 ℃,2.16 kg;

the linear low density polyethylene has a melt index of 2 to 10g/min, preferably 2 to 5g/min, more preferably 2 to 4g/min at 190℃under 2.16 kg.

4. A paving mat according to any of claims 1 to 3, wherein the nano magnesium hydroxide has an aspect ratio of 8/1 to 10/1 and a long axis direction of 80 to 100nm.

5. The paving mat as claimed in any of claims 1 to 4, wherein the nano magnesium hydroxide is modified nano magnesium hydroxide prepared by the following method: based on the total weight of the raw materials, 70-80 weight percent of magnesium hydroxide, 15-25 weight percent of aluminate and 2-5 weight percent of dimethyl maleate are mixed and stirred uniformly to obtain the modified nano magnesium hydroxide.

6. The paving mat of any of claims 1-5, wherein the compatibilizer is one or more of polyethylene grafted maleic anhydride (PE-g-MAH), polyolefin elastomer grafted maleic anhydride (POE-g-MAH), and ethylene propylene diene monomer grafted maleic anhydride (EPDM-g-MAH);

the antistatic agent is one or more of conductive carbon black, graphite and carbon nanotubes.

7. The paving mat of any of claims 1-6, wherein the processing aid is one or more of PE wax and stearic acid, zinc stearate, and calcium stearate;

the antioxidant is one or more of pentaerythritol tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 1,3, 5-trimethyl-2, 4,6- (3, 5-di-tert-butyl-4-hydroxy benzyl) benzene, tris [2, 4-di-tert-butylphenyl ] phosphite and distearyl thiodipropionate.

8. The paving mat of any of claims 1-7, wherein the polyethylene composition, when compression molded into a sheet, has a limiting oxygen index of 30-35 and a sheet resistance of 10 ⁶ -10 ⁸ Omega, bending strength not less than 15MPa, elongation at break not less than 100%, notch impact strength of 12-18kJ/m ² 。

9. The paving mat of any of claims 1-8, wherein the polyethylene composition is prepared by:

(1) Weighing red phosphorus, an antistatic agent, an antioxidant, a processing aid and part of high-density polyethylene according to the weight ratio, primarily mixing, adding into an extruder hopper, and performing melt blending and granulation to obtain a double-resistance master batch;

(2) And (3) carrying out melt blending on the obtained double-resistant master batch, the rest high-density polyethylene, the linear low-density polyethylene, the compatilizer and the nano magnesium hydroxide to obtain the flame-retardant antistatic polyethylene composition.

10. The paving mat as claimed in claim 9, wherein said extruder of step (1) is a reciprocating single screw extruder; the melt blending process in step (2) is performed in a twin screw extruder; in the steps (1) and (2), the operation temperature range of the melt blending process is 135-190 ℃; preferably, the high density polyethylene usage ratio in step (1) to step (2) is 1: (1.55-2.5).