Flame-retardant polyethylene material, preparation method and simulated Christmas tree

Abstract

The invention belongs to the technical field of injection molding materials and discloses a flame retardant polyethylene material, which comprises, by weight, 80-90 parts of low-density polyethylene, 5-10 parts of linear low-density polyethylene, 2-5 parts of bromine antimony flame retardant, 1-3 parts of magnesium hydroxide, 0.5-0.75 parts of antioxidant 1010, 0.5-1.5 parts of surfactant, 0.2-0.8 parts of lubricant, 0.2-0.8 parts of acid absorber, 0.15-0.2 parts of antioxidant 168, 0.01-0.5 The invention discloses a method for preparing a magnesium hydroxide having a bromine-antimony flame retardant and a color powder; the bromine-antimony flame retardant is compounded with decabromodiphenylethane and sodium antimonate with a particle size D90 of 2 to 5 μm; the particle size D90 of the magnesium hydroxide is ≤1.5 μm; the surfactant is a combination of polyethylene glycol 400 dilaurate and polyethylene glycol 400 distearate, polyethylene glycol 600 distearate, polyethylene glycol 400 monooleate, polyethylene glycol 400 dioleate, polyethylene glycol 600 monooleate, and polyethylene glycol 600 dioleate. The magnesium hydroxide of the invention is precipitated on the outer surface of the injection molded product. When the injection molded product burns, the magnesium hydroxide immediately plays a flame retardant role on the outermost layer, thereby improving the flame retardant performance.

Description

Technical Field

[0001] The invention relates to the technical field of injection molding materials, and in particular to a flame-retardant polyethylene material, a preparation method and a simulated Christmas tree. Background Art

[0002] With the development of the times, people's environmental awareness has gradually increased, and the felling of trees has been strictly controlled.

[0003] Among them, the Christmas tree has changed from being cut down from real pine trees to being produced and used as an artificial Christmas tree. Christmas is a very important festival in Western countries, and the Christmas tree is an important decoration for Christmas. Therefore, the demand for artificial Christmas trees is very large. At present, the main materials for the common artificial Christmas tree branches are PVC or flame-retardant polyethylene. PVC has good flame retardant properties, low prices, and a large demand. However, since PVC is not suitable for injection molding, the simulation effect is poor. Flame-retardant polyethylene has good processability and can be used to make various types and colors of artificial Christmas pine branches. In addition, flame-retardant polyethylene has excellent flame retardant properties and will extinguish as soon as it is away from fire, and is deeply loved by European and American buyers.

[0004] Chinese patent 201810057030.4 discloses this type of bromine antimony flame retardant polyethylene material. The invention patent application discloses a flame retardant low-density polyethylene flame retardant. The basic steps are: first, dealkalize the red mud; then, calcine the dealkalized red mud at 400°C to 800°C, and crush it to 300 to 500 mesh; modify the calcined red mud with a titanate coupling agent to obtain modified red mud; melt-blend the modified red mud, decabromodiphenylethane, antimony trioxide and low-density polyethylene, and the mass ratio of each component is: low-density polyethylene: modified red mud: antimony trioxide: decabromodiphenylethane = (75 to 88): (1 to 4): (2.75 to 5.25): (8.25 to 15.75). The prepared low-density polyethylene composite material has an oxygen index of more than 30.0%, and a vertical combustion rating of UL94V-0.

[0005] The specific composition ratio of the above patent makes the flame retardant effect of the polyethylene material reach UL94V-0 level, which is a very good flame retardant polyethylene material. However, since the artificial Christmas tree is placed indoors for decoration, if the flame retardant polyethylene material prepared by the above patent is used for injection molding of artificial Christmas trees, the amount of red mud, antimony trioxide and other substances used will cause certain pollution, which does not meet the more stringent environmental protection agreements in the European and American markets.

[0006] Generally, the amount of flame retardant added to flame retardant polyethylene materials is 10-30%, which will cause the content of pollutants such as lead, arsenic and other elements in the flame retardant polyethylene materials to exceed the content specified in the environmental protection agreement of the European and American markets (the content of lead and arsenic is less than 5ppm), and the addition of flame retardants also reduces the elongation at break, fluidity and other properties of the flame retardant polyethylene materials; if the amount of flame retardant is reduced, the provisions of the environmental protection agreement can be met, and the performance of the flame retardant polyethylene can be effectively improved, but after reducing the amount of flame retardant, the flame retardant properties of the polyethylene material will decrease, especially when used for the production of indoor decorations such as artificial Christmas trees, and the flame retardant property is an indicator that the European and American markets pay more attention to.

[0007] Therefore, it is necessary to develop a flame retardant polyethylene material with high flame retardancy and environmental protection for injection molding into artificial Christmas trees. Summary of the invention

[0008] One of the purposes of the present invention is to provide a flame-retardant polyethylene material, which has high flame retardancy and good properties such as elongation at break, fluidity, etc., is environmentally friendly, and has a high market prospect.

[0009] Another object of the present invention is to provide a method for preparing a flame-retardant polyethylene material. The flame-retardant polyethylene material prepared by the method has high flame retardancy, high toughness and high fluidity, and has good application prospects.

[0010] At the same time, the present invention also provides an artificial Christmas tree, which has a high degree of simulation, meets environmental protection requirements, has high flame retardancy and high safety.

[0011] To achieve the above object, the present invention provides a flame retardant polyethylene material, which comprises the following components by weight:

[0012]

[0013] Among them, the bromine antimony flame retardant is compounded by decabromodiphenylethane and sodium antimonate with a particle size D90 of 2 to 5 μm, and the particle size D90 of the magnesium hydroxide is ≤1.5 μm; the surfactant is a combination of polyethylene glycol 400 dilaurate and polyethylene glycol 400 distearate, polyethylene glycol 600 distearate, polyethylene glycol 400 monooleate, polyethylene glycol 400 dioleate, polyethylene glycol 600 monooleate, and polyethylene glycol 600 dioleate.

[0014] Preferably, the weight ratio of decabromodiphenylethane to sodium antimonate is 1-5:1.

[0015] Preferably, the melt index of the low-density polyethylene is 60 g / 10 min.

[0016] Preferably, the melt index of the linear low-density polyethylene is 20 g / 10 min.

[0017] Preferably, the weight ratio of the antioxidant 168 to the antioxidant 1010 is 1:3-4.

[0018] Preferably, the lubricant is polyethylene wax, and the acid absorbent is calcium stearate.

[0019] Preferably, the weight portion of polyethylene glycol 400 dilaurate in the surfactant is 0.2-0.3 parts.

[0020] Preferably, the color powder includes one or more of phthalocyanine green, permanent yellow, phthalocyanine blue, titanium yellow, titanium dioxide, and carbon black.

[0021] The present invention also provides a method for preparing a flame retardant polyethylene material, comprising the following steps:

[0022] Step 1: low-density polyethylene, linear low-density polyethylene, bromine antimony flame retardant, lubricant, acid absorber, antioxidant 168, magnesium hydroxide, antioxidant 1010 and toner are mixed to form a mixture;

[0023] Step 2: adding the mixture into the twin-screw extruder from the feeding head of the twin-screw extruder, adding the liquid surfactant into the twin-screw extruder from the exhaust port through a loss-in-weight liquid feeder, and extruding the mixture in the twin-screw extruder to obtain a strip of flame-retardant polyethylene material after mixing;

[0024] Step 3: After the strip-shaped flame-retardant polyethylene material is water-cooled, air-dried, and pelletized, it is placed in a mixing barrel and mixed again to obtain the flame-retardant polyethylene material.

[0025] Preferably, the extrusion temperature of the twin-screw extruder in step 2 is 160° C.-175° C., and the vacuum degree is <-0.8 MPa.

[0026] The present invention also provides an artificial Christmas tree, which is obtained by injection molding the flame-retardant polyethylene material.

[0027] Beneficial Effects

[0028] Compared with the prior art, the present invention has at least the following advantages:

[0029] (1) The present invention utilizes the property that polyethylene glycol 400 dilaurate will bring out tiny particles of matter and precipitate on the outer surface of the injection-molded product during injection molding, so that the outer surface of the injection-molded artificial Christmas tree has magnesium hydroxide particles with a particle size of D90≤1.5μm. Magnesium hydroxide is precipitated on the outer surface of the injection-molded product. When the injection-molded product burns, magnesium hydroxide immediately plays a flame retardant role on the outermost layer, thereby improving the flame retardant performance;

[0030] Since the flame retardant mechanism of magnesium hydroxide is that it decomposes when heated to absorb the heat from the surface of the burning material to achieve flame retardant effect, and releases a large amount of water to dilute the oxygen on the surface of the burning material, the active magnesium oxide generated by the decomposition adheres to the surface of the combustible material and further prevents the combustion; therefore, the particle distribution of magnesium hydroxide in the injection molded product has an impact on the flame retardant performance. In the present invention, the antioxidant 1010 brings out magnesium hydroxide particles with a small particle size during precipitation, so that the magnesium hydroxide particles are distributed on the surface of the injection molded product, thereby achieving the best flame retardant effect;

[0031] (2) The present invention uses polyethylene glycol 400 dilaurate in combination with other specific surfactants, so that the magnesium hydroxide particles brought out are more evenly distributed on the outer surface of the injection molded product, and polyethylene glycol 400 dilaurate is prevented from bringing out other substances to the outer surface of the injection molded product, thereby affecting the flame retardant properties and mechanical properties of the injection molded product;

[0032] (3) The present invention utilizes the characteristic that a large dose of antioxidant 1010 will be partially precipitated on the outer surface of the injection molded product during injection molding, and combines it with the characteristic that polyethylene glycol 400 dilaurate brings out tiny particles of matter and precipitates on the outer surface of the injection molded product during injection molding, so that polyethylene glycol 400 dilaurate preferentially precipitates antioxidant 1010 and magnesium hydroxide with a smaller particle size during injection molding, thereby avoiding that sodium antimonate with a larger particle size is completely precipitated on the outer surface of the injection molded product, resulting in a reduction in the synergistic flame retardant effect of bromine antimony; at the same time, the dosage of antioxidant 1010 is controlled within a more appropriate range to avoid the presence of excessive antioxidant 1010 affecting the mechanical properties of the artificial Christmas tree;

[0033] (4) The present invention adopts sodium antimonate with a particle size D90 of 2 to 5 μm as the synergistic flame retardant component of the brominated flame retardant. On the one hand, the sodium antimonate with a particle size D90 < 5 μm has better dispersibility and effectively improves the synergistic flame retardant effect; on the other hand, the particle size needs to be slightly larger than 1.5 μm to avoid that part of the polyethylene glycol 400 dilaurate will also bring the sodium antimonate particles out of the outer surface of the injection molded product during injection molding, resulting in a decrease in the synergistic flame retardant effect of sodium antimonate and decabromodiphenylethane;

[0034] (5) The present invention can achieve a high flame retardant effect by adding only a small amount of flame retardant, and the polyethylene material retains high physical properties, so that the injection-molded artificial Christmas tree retains sufficient toughness, thereby increasing market competitiveness. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0036] In order to explain the technical content of the present invention in detail, further description is given below in conjunction with the implementation modes.

[0037] In the present embodiment and comparative example, the melt index of the low-density polyethylene is 60 g / 10 min, and the melt index of the linear low-density polyethylene is 20 g / 10 min. Unless otherwise specified, the components used are all commercially available products.

[0038] In the present embodiment and the comparative example, the water cooling process is to cool the strip flame-retardant polyethylene material to 35°C or below by water with a temperature below 35°C, the air-drying process only needs to blow dry the moisture on the surface of the strip flame-retardant polyethylene material, and the pelletizing process is to cut the strip flame-retardant polyethylene material into cylinders with a length of 3-5mm and a diameter of 2-4mm; the above processes are all prior arts, and the effects achieved can also be achieved by other processes or technologies, and are not the technical problems to be solved by the present invention, so they are not described or limited in depth.

[0039] Example 1

[0040] A flame retardant polyethylene material is prepared by the following steps:

[0041] Step 1: by weight, 80 parts of low-density polyethylene, 10 parts of linear low-density polyethylene, 3 parts of decabromodiphenylethane and 1 part of sodium antimonate with a particle size D90 of 2 μm, 0.2 parts of polyethylene wax, 0.2 parts of calcium stearate, 0.15 parts of antioxidant 168, 1 part of magnesium hydroxide with a particle size D90 of 1.5 μm, 0.5 parts of antioxidant 1010 and 0.01 parts of color powder are mixed to form a mixture A;

[0042] Step 2: adding the mixture into the twin-screw extruder from the feeding head of the twin-screw extruder, adding 0.4 parts of polyethylene glycol 400 dilaurate and 0.1 parts of polyethylene glycol 600 distearate into the twin-screw extruder from the exhaust port of the twin-screw extruder, and extruding the mixture, polyethylene glycol 400 dilaurate and polyethylene glycol 600 distearate in the twin-screw extruder after mixing to obtain a strip of flame-retardant polyethylene material, wherein the extrusion temperature of the twin-screw extruder is 160° C. and the vacuum degree is -0.7 MPa;

[0043] Step 3: After the strip-shaped flame-retardant polyethylene material is water-cooled, air-dried, and pelletized, it is placed in a mixing barrel and mixed again to obtain a cylindrical flame-retardant polyethylene material.

[0044] Example 2

[0045] A flame retardant polyethylene material is prepared by the following steps:

[0046] Step 1: by weight, 80 parts of low-density polyethylene, 10 parts of linear low-density polyethylene, 3 parts of decabromodiphenylethane and 1 part of sodium antimonate with a particle size D90 of 2 μm, 0.2 parts of polyethylene wax, 0.2 parts of calcium stearate, 0.15 parts of antioxidant 168, 1 part of magnesium hydroxide with a particle size D90 of 1.5 μm, 0.5 parts of antioxidant 1010 and 0.01 parts of color powder are mixed to form a mixture A;

[0047] Step 2: adding the mixture into the twin-screw extruder from the feeding head of the twin-screw extruder, adding 0.2 parts of polyethylene glycol 400 dilaurate and 0.3 parts of polyethylene glycol 600 distearate into the twin-screw extruder from the exhaust port of the twin-screw extruder, and extruding the mixture, polyethylene glycol 400 dilaurate and polyethylene glycol 600 distearate in the twin-screw extruder after mixing to obtain a strip of flame-retardant polyethylene material, wherein the extrusion temperature of the twin-screw extruder is 160° C. and the vacuum degree is -0.7 MPa;

[0048] Step 3: After the strip-shaped flame-retardant polyethylene material is water-cooled, air-dried, and pelletized, it is placed in a mixing barrel and mixed again to obtain a cylindrical flame-retardant polyethylene material.

[0049] Example 3

[0050] A flame retardant polyethylene material is prepared by the following steps:

[0051] Step 1: by weight, 80 parts of low-density polyethylene, 10 parts of linear low-density polyethylene, 3 parts of decabromodiphenylethane and 1 part of sodium antimonate with a particle size D90 of 2 μm, 0.2 parts of polyethylene wax, 0.2 parts of calcium stearate, 0.15 parts of antioxidant 168, 1 part of magnesium hydroxide with a particle size D90 of 1.5 μm, 0.5 parts of antioxidant 1010 and 0.01 parts of color powder are mixed to form a mixture A;

[0052] Step 2: adding the mixture into the twin-screw extruder from the feeding head of the twin-screw extruder, adding 0.3 parts of polyethylene glycol 400 dilaurate and 1.2 parts of polyethylene glycol 600 distearate into the twin-screw extruder from the exhaust port of the twin-screw extruder, and extruding the mixture, polyethylene glycol 400 dilaurate and polyethylene glycol 600 distearate in the twin-screw extruder after mixing to obtain a strip of flame-retardant polyethylene material, wherein the extrusion temperature of the twin-screw extruder is 160° C. and the vacuum degree is -0.7 MPa;

[0053] Step 3: After the strip-shaped flame-retardant polyethylene material is water-cooled, air-dried, and pelletized, it is placed in a mixing barrel and mixed again to obtain a cylindrical flame-retardant polyethylene material.

[0054] Example 4

[0055] A flame retardant polyethylene material is prepared by the following steps:

[0056] Step 1: by weight, 80 parts of low-density polyethylene, 10 parts of linear low-density polyethylene, 3 parts of decabromodiphenylethane and 1 part of sodium antimonate with a particle size D90 of 5 μm, 0.2 parts of polyethylene wax, 0.2 parts of calcium stearate, 0.15 parts of antioxidant 168, 1 part of magnesium hydroxide with a particle size D90 of 1 μm, 0.5 parts of antioxidant 1010 and 0.01 parts of color powder are mixed to form a mixture;

[0057] Step 2: adding the mixture into the twin-screw extruder from the feeding head of the twin-screw extruder, adding 0.25 parts of polyethylene glycol 400 dilaurate and 0.75 parts of polyethylene glycol 600 dioleate into the twin-screw extruder from the exhaust port of the twin-screw extruder through a loss-in-weight liquid feeder, and extruding the mixture, polyethylene glycol 400 dilaurate and polyethylene glycol 600 dioleate in the twin-screw extruder after mixing to obtain a strip of flame-retardant polyethylene material, wherein the extrusion temperature of the twin-screw extruder is 165° C. and the vacuum degree is -0.7 MPa;

[0058] Step 3: After the strip-shaped flame-retardant polyethylene material is water-cooled, air-dried, and pelletized, it is placed in a mixing barrel and mixed again to obtain a cylindrical flame-retardant polyethylene material.

[0059] Example 5

[0060] A flame retardant polyethylene material is prepared by the following steps:

[0061] Step 1: by weight, 90 parts of low-density polyethylene, 5 parts of linear low-density polyethylene, a bromine antimony flame retardant prepared by compounding 4 parts of decabromodiphenylethane and 1 part of sodium antimonate with a particle size D90 of 5 μm, 0.6 parts of polyethylene wax, 0.5 parts of calcium stearate, 0.2 parts of antioxidant 168, 3 parts of magnesium hydroxide with a particle size D90 of 1.3 μm, 0.75 parts of antioxidant 1010 and 0.5 parts of color powder are mixed to form a mixture;

[0062] Step 2: Add the mixture A into the twin-screw extruder from the feeding head of the twin-screw extruder, add 0.3 parts of polyethylene glycol 400 dilaurate and 1.2 parts of polyethylene glycol 400 monooleate into the twin-screw extruder from the exhaust port of the twin-screw extruder through a loss-in-weight liquid feeder, and extrude the mixture, polyethylene glycol 400 dilaurate and polyethylene glycol 400 monooleate in the twin-screw extruder after mixing to obtain a strip of flame-retardant polyethylene material, wherein the extrusion temperature of the twin-screw extruder is 175° C. and the vacuum degree is -0.7 MPa;

[0063] Step 3: After the strip-shaped flame-retardant polyethylene material is water-cooled, air-dried, and pelletized, it is placed in a mixing barrel and mixed again to obtain a cylindrical flame-retardant polyethylene material.

[0064] Example 6

[0065] A flame retardant polyethylene material is prepared by the following steps:

[0066] Step 1: by weight, 85 parts of low-density polyethylene, 8 parts of linear low-density polyethylene, 4 parts of decabromodiphenylethane and 1 part of sodium antimonate with a particle size D90 of 3 μm, 0.6 parts of polyethylene wax, 0.5 parts of calcium stearate, 0.2 parts of antioxidant 168, 2 parts of magnesium hydroxide with a particle size D90 of 1.5 μm, 0.75 parts of antioxidant 1010 and 0.5 parts of color powder are mixed to form a mixture;

[0067] Step 2: adding the mixture into the twin-screw extruder from the feeding head of the twin-screw extruder, adding 0.25 parts of polyethylene glycol 400 dilaurate and 0.75 parts of polyethylene glycol 600 distearate into the twin-screw extruder from the exhaust port of the twin-screw extruder through a loss-in-weight liquid feeder, and extruding the mixture, polyethylene glycol 400 dilaurate and polyethylene glycol 600 distearate in the twin-screw extruder after mixing to obtain a strip of flame-retardant polyethylene material, wherein the extrusion temperature of the twin-screw extruder is 165° C. and the vacuum degree is -0.7 MPa;

[0068] Step 3: After the strip-shaped flame-retardant polyethylene material is water-cooled, air-dried, and pelletized, it is placed in a mixing barrel and mixed again to obtain a cylindrical flame-retardant polyethylene material.

[0069] Example 7

[0070] It is substantially the same as Example 6, except that the weight portion of the antioxidant 168 is 0.15 parts.

[0071] Comparative Example 1

[0072] It is substantially the same as Example 6, except that the sodium antimonate with a particle size D90 of 3 μm is replaced by antimony trioxide with a particle size D90 of 3 μm.

[0073] Comparative Example 2

[0074] It is substantially the same as Example 6, except that the particle size D90 of the magnesium hydroxide is 2 μm.

[0075] Comparative Example 3

[0076] It is substantially the same as Example 6, except that the antioxidant 1010 is replaced by an antioxidant 168 of the same weight.

[0077] Comparative Example 4

[0078] It is substantially the same as Example 6, except that the particle size D90 of sodium antimonate is 7 μm.

[0079] Comparative Example 5

[0080] It is substantially the same as Example 6, except that the particle size D90 of sodium antimonate is 1 μm.

[0081] Comparative Example 6

[0082] A flame retardant polyethylene material is prepared by the following steps:

[0083] Step 1: by weight, 85 parts of low-density polyethylene, 8 parts of linear low-density polyethylene, 12 parts of decabromodiphenylethane and 3 parts of sodium antimonate with a particle size D90 of 3 μm, 0.6 parts of polyethylene wax, 0.5 parts of calcium stearate, 0.2 parts of antioxidant 168, 0.75 parts of antioxidant 1010 and 0.5 parts of color powder are mixed to form a mixture;

[0084] Step 2: adding the mixture into the twin-screw extruder from the feeding head of the twin-screw extruder, adding 0.25 parts of polyethylene glycol 400 dilaurate and 0.75 parts of polyethylene glycol 600 distearate into the twin-screw extruder from the exhaust port of the twin-screw extruder through a loss-in-weight liquid feeder, and extruding the mixture, polyethylene glycol 400 dilaurate and polyethylene glycol 600 distearate in the twin-screw extruder after mixing to obtain a strip of flame-retardant polyethylene material, wherein the extrusion temperature of the twin-screw extruder is 165° C. and the vacuum degree is -0.7 MPa;

[0085] Step 4: After the strip-shaped flame-retardant polyethylene material is water-cooled, air-dried, and pelletized, it is placed in a mixing barrel and mixed again to obtain a cylindrical flame-retardant polyethylene material.

[0086] Comparative Example 7

[0087] A flame retardant polyethylene material is prepared by the following steps:

[0088] Step 1: by weight, 85 parts of low-density polyethylene, 8 parts of linear low-density polyethylene, 4 parts of decabromodiphenylethane and 1 part of sodium antimonate with a particle size D90 of 3 μm, 0.6 parts of polyethylene wax, 0.5 parts of calcium stearate, 0.2 parts of antioxidant 168, 2 parts of magnesium hydroxide with a particle size D90 of 1.5 μm, 0.75 parts of antioxidant 1010 and 0.5 parts of color powder are mixed to form a mixture;

[0089] Step 2: adding the mixture into the twin-screw extruder from the feeding head of the twin-screw extruder, adding 1 part of polyethylene glycol 400 dilaurate into the twin-screw extruder from the exhaust port of the twin-screw extruder through a loss-in-weight liquid feeder, and extruding the mixture and polyethylene glycol 400 dilaurate in the twin-screw extruder after mixing to obtain a strip of flame-retardant polyethylene material, wherein the extrusion temperature of the twin-screw extruder is 165° C. and the vacuum degree is -0.7 MPa;

[0090] Step 3: After the strip-shaped flame-retardant polyethylene material is water-cooled, air-dried, and pelletized, it is placed in a mixing barrel and mixed again to obtain a cylindrical flame-retardant polyethylene material.

[0091] Comparative Example 8

[0092] A flame retardant polyethylene material is prepared by the following steps:

[0093] Step 1: by weight, 85 parts of low-density polyethylene, 8 parts of linear low-density polyethylene, 4 parts of decabromodiphenylethane and 1 part of sodium antimonate with a particle size D90 of 3 μm, 0.6 parts of polyethylene wax, 0.5 parts of calcium stearate, 0.2 parts of antioxidant 168, 2 parts of magnesium hydroxide with a particle size D90 of 1.5 μm, 0.75 parts of antioxidant 1010 and 0.5 parts of color powder are mixed to form a mixture;

[0094] Step 2: adding the mixture into the twin-screw extruder from the feeding head of the twin-screw extruder, adding 1 part of polyethylene glycol 600 distearate into the twin-screw extruder from the exhaust port of the twin-screw extruder through a loss-in-weight liquid feeder, and extruding the mixture and polyethylene glycol 600 distearate in the twin-screw extruder after mixing to obtain a strip of flame-retardant polyethylene material, wherein the extrusion temperature of the twin-screw extruder is 165° C. and the vacuum degree is -0.7 MPa;

[0095] Step 3: After the strip-shaped flame-retardant polyethylene material is water-cooled, air-dried, and pelletized, it is placed in a mixing barrel and mixed again to obtain a cylindrical flame-retardant polyethylene material.

[0096] Comparative Example 9

[0097] It is generally the same as Example 6, except that the weight portion of the antioxidant 1010 in step 1 is 0.3 parts.

[0098] Comparative Example 10

[0099] It is generally the same as Example 6, except that the weight portion of the antioxidant 1010 in step 1 is 1 part.

[0100] Performance Testing

[0101] The flame-retardant polyethylene materials obtained in Examples 1-4 and Comparative Examples 1-6 were injection molded using a horizontal injection molding machine to obtain simulated Christmas tree branch samples. The molding process conditions were: injection temperature 270° C.; injection pressure 150 MPa; holding time 3 s; and cooling time 5 s.

[0102] The performance test standards are as follows:

[0103] Melt index: tested according to ASTM D-1238 standard (190℃ / 2.16Kg);

[0104] Elongation at break: tested according to ASTM D-638 standard;

[0105] Izod notched impact strength: tested in accordance with ASTM D-256;

[0106] Flame retardant test: directly ignite the simulated Christmas tree branch sample with an alcohol lamp from the top for 10 seconds, then remove the alcohol lamp and count down at the same time to calculate how long it will take for the simulated Christmas tree branch sample to extinguish itself;

[0107] The performance test results are shown in Table 1:

[0108] Table 1 Performance test results of Examples 1-7 and Comparative Examples 1-10

[0109]

[0110] According to the results of Example 6 and Comparative Example 1, replacing sodium antimonate with an equal amount of antimony trioxide does not have a significant effect on the mechanical properties and flame retardant properties of the flame-retardant polyethylene material. However, due to the low cost of sodium antimonate and the lead content and arsenic content in antimony trioxide being greater than 500 ppm, the use of antimony trioxide as a synergistic flame retardant can easily exceed the stringent environmental protection agreements in Europe and the United States, which hinders the European and American markets for artificial Christmas trees. Therefore, the technical solution of the present invention does not consider using antimony trioxide as a synergistic flame retardant in the bromine antimony flame retardant.

[0111] According to the results of Example 6 and Comparative Example 2, the use of magnesium hydroxide with a particle size D90 greater than 1.5 μm will result in that polyethylene glycol 400 dilaurate will not be able to bring out the magnesium hydroxide during the precipitation process on the outer surface when it is injection molded into simulated Christmas tree branches, resulting in a significant reduction in the flame retardant effect of the magnesium hydroxide, thereby reducing the flame retardant properties of the simulated Christmas tree branches.

[0112] According to the results of Example 6 and Comparative Example 3, the use of antioxidant 1010 in the present invention can not only achieve the effect of synergistically protecting the flame-retardant polyethylene material injection molding processing with antioxidant 168 and maintaining the mechanical properties of the flame-retardant polyethylene material, but also can partially analyze the characteristics of the outer surface of the simulated Christmas tree branches through a large amount of antioxidant 1010, precipitate together with polyethylene glycol 400 dilaurate on the outer surface of the simulated Christmas tree branches, and bring out magnesium hydroxide particles together. At the same time, as a preferred option for the precipitation of polyethylene glycol 400 dilaurate, it effectively inhibits the accompanying precipitation of sodium antimonate with a larger particle size, thereby avoiding uneven dispersion of sodium antimonate and reducing the flame retardant effect.

[0113] According to the results of Example 6 and Comparative Example 4, the particle size of sodium antimonate is too large, which affects the dispersibility of the sodium antimonate particles and also affects the flame retardant properties. At the same time, due to the uneven dispersion of the sodium antimonate particles, the flame retardant properties of the head and root of the simulated Christmas tree branches will be significantly different.

[0114] According to the results of Example 6 and Comparative Example 5, the precipitation of polyethylene glycol 400 dilaurate and part of the antioxidant 1010 during the injection molding process also brought out sodium antimonate with a D90 of 1 μm, resulting in uneven distribution of sodium antimonate and decabromodiphenylethane, which reduced the synergistic flame retardant effect, reduced the flame retardant properties of the flame retardant polyethylene material, and also led to a more obvious difference in the flame retardant properties of the simulated Christmas tree branch head and root.

[0115] According to the results of Example 6 and Comparative Example 6, although increasing the weight of the bromine-antimony flame retardant can improve the flame retardant performance, the mechanical properties of the flame-retardant polyethylene material will also be greatly reduced, affecting important performance indicators such as the toughness of the injection molded product, and reducing the market competitiveness of the manufactured artificial Christmas tree; at the same time, compared with the technical solution of the present invention, the technical solution of Comparative Example 6 does not have magnesium hydroxide particles distributed on the outer surface of the branches of the artificial Christmas tree for effective flame retardancy, so the self-extinguishing time after ignition is also extended.

[0116] According to the results of Example 6 and Comparative Example 7, it can be seen that simply using polyethylene glycol 400 dilaurate as a surfactant will cause most of the polyethylene glycol 400 dilaurate, antioxidant 1010 and magnesium hydroxide particles to precipitate at the head of the simulated Christmas tree branches with a smaller diameter during injection molding; the reason may be that during the injection molding process, the simulated Christmas pine branches are injected first at the head, and the middle part is injected last, which will cause the head to cool first, so the surfactant will more easily form a surfactant layer on the head surface. The mixture of polyethylene glycol 600 distearate and polyethylene glycol 400 dilaurate prevents most of the polyethylene glycol 400 dilaurate, antioxidant 1010 and magnesium hydroxide particles from precipitating on the head of the simulated Christmas pine branch. Instead, they precipitate more evenly on the entire outer surface of the simulated Christmas pine branch. The reason may be that polyethylene glycol 600 distearate slows down the precipitation rate of polyethylene glycol 400 dilaurate, thereby reducing the effect of the cooling path of the simulated Christmas pine branch on the precipitation of polyethylene glycol 400 dilaurate, and finally the precipitation position of polyethylene glycol 400 dilaurate is more uniform.

[0117] According to the results of Example 6 and Comparative Example 8, it can be seen that the use of polyethylene glycol 600 distearate alone cannot precipitate on the outer surface of the simulated Christmas tree branches during injection molding, thereby failing to bring out the antioxidant 1010 and the magnesium hydroxide particles, resulting in a greatly reduced flame retardant effect of the magnesium hydroxide particles, thereby reducing the flame retardant properties of the simulated Christmas tree branches.

[0118] According to the results of Example 6 and Comparative Example 9, since a small dose of antioxidant 1010 is difficult to precipitate to the outer surface of the simulated Christmas tree branches along with polyethylene glycol 400 dilaurate, some sodium antimonate particles will be brought out of the outer surface of the simulated Christmas tree branches by polyethylene glycol 400 dilaurate as a secondary option, resulting in uneven distribution of sodium antimonate particles and reduced synergistic flame retardant effect of bromine antimony flame retardant, thereby affecting the overall flame retardant properties of the simulated Christmas tree branches.

[0119] According to the results of Example 6 and Comparative Example 10, although a large amount of antioxidant 1010 will not have much effect on the precipitation effect of polyethylene glycol 400 dilaurate and magnesium hydroxide particles, excessive use of antioxidant 1010 will affect the mechanical properties of the simulated Christmas tree branches.

[0120] In summary, the technical solution of the present invention adopts a reasonable combination of surfactants and the selection of antioxidant 1010, so that the flame retardant effect of magnesium hydroxide and bromine antimony flame retardant is maximized, the flame retardant properties of the simulated Christmas tree are effectively enhanced, and the amount of flame retardant is reduced, and the mechanical properties of the simulated Christmas tree are effectively improved; and the present invention adopts a reasonable dosage and ratio of antioxidant 1010 and antioxidant 168, so that the mechanical properties of the simulated Christmas tree can be maintained in a better range.

[0121] The embodiments presented herein are only embodiments selected according to the combination of all possible embodiments. The appended claims should not be limited by the embodiments describing the present invention. Some numerical ranges used in the claims include sub-ranges therein, and the changes in these ranges should also be covered by the appended claims.

Claims

1. A flame retardant polyethylene material, characterized in that: By weight, it includes the following components: 80-90 parts of low density polyethylene Linear low density polyethylene 5-10 parts Bromine antimony flame retardant 2-5 parts 1-3 parts of magnesium hydroxide Antioxidant 1010 0.5-0.75 parts Surfactant 0.5-1.5 parts Lubricant 0.2-0.8 parts Acid absorbent 0.2-0.8 parts Antioxidant 168 0.15-0.2 parts Color powder 0.01-0.5 parts; Among them, the bromine antimony flame retardant is compounded by decabromodiphenylethane and sodium antimonate with a particle size D90 of 2~5μm, and the weight ratio of decabromodiphenylethane to sodium antimonate is 3-4:1, and the particle size D90 of the magnesium hydroxide is ≤1.5μm; the surfactant is a combination of polyethylene glycol 400 dilaurate and polyethylene glycol 400 distearate, polyethylene glycol 600 distearate, polyethylene glycol 400 monooleate, and polyethylene glycol 600 dioleate.

2. The flame retardant polyethylene material according to claim 1, characterized in that: The low-density polyethylene has a melt index of 60 g / 10 min.

3. The flame retardant polyethylene material according to claim 1, characterized in that: The linear low-density polyethylene has a melt index of 20 g / 10 min.

4. The flame retardant polyethylene material according to claim 1, characterized in that: The weight ratio of the antioxidant 168 to the antioxidant 1010 is 1:3-4.

5. The flame retardant polyethylene material according to claim 1, characterized in that: The lubricant is polyethylene wax, and the acid absorbent is calcium stearate.

6. The flame retardant polyethylene material according to claim 1, characterized in that: The weight portion of polyethylene glycol 400 dilaurate in the surfactant is 0.2-0.3 parts.

7. A method for preparing a flame retardant polyethylene material according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: low-density polyethylene, linear low-density polyethylene, bromine antimony flame retardant, lubricant, acid absorber, antioxidant 168, magnesium hydroxide, antioxidant 1010 and toner are mixed to form a mixture; Step 2: adding the mixture into the twin-screw extruder from the feeding head of the twin-screw extruder, adding the liquid surfactant into the twin-screw extruder from the exhaust port through a loss-in-weight liquid feeder, and extruding the mixture in the twin-screw extruder to obtain a strip of flame-retardant polyethylene material after mixing; Step 3: After the strip-shaped flame-retardant polyethylene material is water-cooled, air-dried, and pelletized, it is placed in a mixing barrel and mixed again to obtain the flame-retardant polyethylene material.

8. The method for preparing a flame retardant polyethylene material according to claim 7, characterized in that: In step 2, the extrusion temperature of the twin-screw extruder is 160° C.-175° C., and the vacuum degree is less than -0.8 MPa.

9. An artificial Christmas tree, characterized in that: The flame retardant polyethylene material is injection molded according to any one of claims 1 to 6.

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