阅读说明：本技术 一种无卤阻燃高密度聚乙烯材料及制备方法和应用 (Halogen-free flame-retardant high-density polyethylene material and preparation method and application thereof ) 是由 沈旭渠 陈锐彬 刘鹏辉 黄方雁 吕伟 刘俊 汪洋 于 2019-09-12 设计创作，主要内容包括：本发明实施例提供了一种无卤阻燃高密度聚乙烯材料及制备方法和应用。上述无卤阻燃高密度聚乙烯材料,阻燃性能UL94达到了V-2级别,力学性能优异,制件的断裂伸长率达到了842％,可重复回收利用,环保无卤,燃烧时不产生有腐蚀性气体,自熄性优良,解决了现有技术中,HDPE的无卤阻燃技术存在的力学性能和溴锑阻燃的环保问题。(The embodiment of the invention provides a halogen-free flame-retardant high-density polyethylene material, and a preparation method and application thereof. According to the halogen-free flame-retardant high-density polyethylene material, the flame retardant property UL94 reaches the V-2 level, the mechanical property is excellent, the breaking elongation of a workpiece reaches 842%, the halogen-free flame-retardant high-density polyethylene material can be recycled, is environment-friendly and halogen-free, does not generate corrosive gas during combustion, has excellent self-extinguishing property, and solves the problems of mechanical property and bromine and antimony flame retardance in the halogen-free flame retardant technology of HDPE in the prior art.)

1. The halogen-free flame-retardant high-density polyethylene material is characterized by comprising the following raw materials in parts by weight:

HDPE: 80-95 parts of a water-soluble polymer,

halogen-free compound flame retardant: 5 to 15 parts of (A) a water-soluble polymer,

flame retardant synergist: 0.1 part by weight of a reaction kettle,

antioxidant: 0.2 to 0.8 part by weight,

lubricant: 0.3 to 0.7 portion.

2. The halogen-free flame-retardant high-density polyethylene material as claimed in claim 1, wherein the HDPE has a flexural modulus of 750-900 MPa.

3. The halogen free flame retardant high density polyethylene material according to claim 1, characterized in that the elongation at break of the HDPE is > 800%.

4. The halogen-free flame-retardant high-density polyethylene material according to claim 1, wherein the halogen-free compound flame retardant is a P-N compound flame retardant, and the mass ratio of the P-series flame retardant to the N-series flame retardant in the P-N compound flame retardant is 1: (0.5 to 10).

5. The halogen-free, flame-retardant, high-density polyethylene material of claim 4, wherein the P-based flame retardant comprises at least one of hypophosphorous acid, aluminum hypophosphite, calcium hypophosphite, aluminum diethylphosphinate, and aluminum phenylphosphinate.

6. The halogen-free flame-retardant high-density polyethylene material according to claim 4, wherein the N-based flame retardant comprises at least one of melamine, melamine cyanurate, dimelamine pyrophosphate, melamine borate, melamine orthophosphate and melamine polyphosphate.

7. The halogen-free flame-retardant high-density polyethylene material according to claim 1, wherein the antioxidant is 4, 4' -butylidene bis (6-tert-butyl-3-methylphenol) and dioctadecyl pentaerythritol diphosphite in a mass ratio of 1: (2-6) a compound antioxidant.

8. The halogen-free, flame-retardant, high-density polyethylene material according to claim 1, characterized in that the lubricant comprises at least one of stearic acid, stearate esters, ethylene bis-stearamide, polyethylene wax.

9. The preparation method of the halogen-free flame-retardant high-density polyethylene material according to any one of claims 1 to 8, characterized by comprising the following steps:

s1: weighing the HDPE, the halogen-free compound flame retardant, the antioxidant and the lubricant according to the proportion, and uniformly mixing;

s2: and (3) mixing the materials by a double-screw extruder, and extruding and granulating to obtain the halogen-free flame-retardant low-density polyethylene material.

10. The use of the halogen-free flame-retardant high-density polyethylene material according to any one of claims 1 to 8 or the halogen-free flame-retardant low-density polyethylene material prepared by the preparation method according to claim 9 in non-load-bearing plastic boxes and trash cans.

Technical Field

The invention belongs to the technical field of flame-retardant materials, and particularly relates to a halogen-free flame-retardant high-density polyethylene material, and a preparation method and application thereof.

Background

High Density Polyethylene (HDPE) is a white powder or granular product, has no toxicity and odor, has a crystallinity of 80-90%, a softening point of 125-l 35 ℃, and a use temperature of 100 ℃. The hardness, tensile strength and creep property of HDPE are superior to those of low density polyethylene, and the HDPE has good wear resistance, electrical insulation property, toughness and cold resistance, good chemical stability, and is insoluble in any organic solvent at room temperature. HDPE is resistant to corrosion by acids, bases and various salts, the film has low permeability to water vapor and air, low water absorption, poor aging resistance, and environmental stress cracking resistance inferior to that of low density polyethylene. The high-density polyethylene resin is a flammable material, has a very low oxygen index of only about 19 percent, and has potential fire risks due to melting and dropping during combustion, so that the wider application of the high-density polyethylene resin is greatly limited. Therefore, HDPE must be flame retardant treated.

The flame retardant commonly used in HDPE in the market at present is a halogen-antimony flame retardant system, a hydroxide system and an APP flame retardant system, the halogen flame retardant has the advantages of stable flame retardant performance, can prepare flame retardant HDPE meeting various UL standards according to requirements, and has the main defects of more smoke generated during combustion, generation of corrosive gas and toxic gas and formation of secondary pollution. With the increasing awareness of environmental protection and the increasing emphasis on environmental protection, the application of halogen-based flame retardants is more and more strictly limited. The addition amount of the flame retardant of the hydroxide system and the APP flame retardant system is large, the mechanical property is seriously damaged, and only one flame retardant level can be reached.

For some HDPE products requiring halogen-free flame retardance, such as some plastic boxes and garbage cans which are not load-bearing parts, the flame retardance requirement is low, the requirement is in accordance with UL 94V-2, the flame retardant is not separated out, but the toughness requirement is high, and the existing flame retardance technology cannot meet the market requirement.

Disclosure of Invention

In order to solve the problems of mechanical property and bromine and antimony flame retardance in the halogen-free flame retardant technology of HDPE in the prior art, one of the purposes of the embodiment of the invention is to provide a halogen-free flame retardant high-density polyethylene material. The second objective of the embodiments of the present invention is to provide a preparation method of the halogen-free flame-retardant high-density polyethylene material. The embodiment of the invention also aims to provide the application of the halogen-free flame-retardant high-density polyethylene material in non-load-bearing plastic boxes and garbage cans.

In order to achieve the purpose, the embodiment of the invention adopts the following technical scheme:

a halogen-free flame-retardant high-density polyethylene material comprises the following raw materials in parts by weight:

HDPE: 80-95 parts of a water-soluble polymer,

halogen-free compound flame retardant: 5 to 15 parts of (A) a water-soluble polymer,

flame retardant synergist: 0.1 part by weight of a reaction kettle,

antioxidant: 0.2 to 0.8 part by weight,

lubricant: 0.3 to 0.7 portion.

The halogen-free flame-retardant high-density polyethylene material has the flame retardant property UL94 reaching V-2 level, excellent mechanical property, the elongation at break of a workpiece reaching 842%, repeated recycling, environmental protection, no halogen, no corrosive gas generated during combustion and excellent self-extinguishing property.

Preferably, the HDPE has a flexural modulus of 750-900 MPa.

Preferably, the HDPE has an elongation at break of > 800%.

Preferably, the HDPE has a melt index of 4g/10min to 50g/10min at 2.16kg under test conditions at 190 ℃.

Preferably, the halogen-free compound flame retardant is a P-N compound flame retardant, and the mass ratio of the P-series flame retardant to the N-series flame retardant in the P-N compound flame retardant is 1: (0.5 to 10).

Further preferably, the mass ratio of the P-series flame retardant to the N-series flame retardant in the P-N compound flame retardant is 1: (0.75 to 1.2).

Further preferably, the P-based flame retardant includes at least one of hypophosphorous acid, aluminum hypophosphite, calcium hypophosphite, aluminum diethylphosphinate, and aluminum phenylphosphinate.

Still more preferably, the P-based flame retardant comprises aluminum hypophosphite.

Further preferably, the N-based flame retardant includes at least one of melamine, melamine cyanurate, dimelamine pyrophosphate, melamine borate, melamine orthophosphate, and melamine polyphosphate.

Still more preferably, the N-based flame retardant comprises one of melamine and melamine cyanurate.

Preferably, the flame retardant synergist is at least one of 2, 3-dimethyl-2, 3-diphenyl butane or p-cumene polymer.

Further preferably, the flame retardant synergist is 2, 3-dimethyl-2, 3-diphenylbutane.

Preferably, the antioxidant is 4, 4' -butylidene bis (6-tertiary butyl-3-methylphenol) and dioctadecyl pentaerythritol diphosphite in a mass ratio of 1: (2-6) a compound antioxidant.

Further preferably, the antioxidant is 4, 4' -butylidene bis (6-tertiary butyl-3-methylphenol) and dioctadecyl pentaerythritol diphosphite in a mass ratio of 1: (3-5) a compound antioxidant.

Still more preferably, the antioxidant is 4, 4' -butylidene bis (6-tert-butyl-3-methylphenol) and dioctadecyl pentaerythritol diphosphite in a mass ratio of 1: 4 a compound antioxidant.

Preferably, the lubricant comprises at least one of stearic acid, stearate ester, ethylene bis-stearamide, polyethylene wax.

Further preferably, the lubricant comprises at least one of stearic acid, calcium stearate, zinc stearate, butyl stearate, ethylene bis stearamide, polyethylene wax.

Still further preferably, the lubricant comprises ethylene bis stearamide.

The preparation method of the halogen-free flame-retardant high-density polyethylene material comprises the following steps:

s1: weighing the HDPE, the halogen-free compound flame retardant, the antioxidant and the lubricant according to the proportion, and uniformly mixing;

s2: and (3) mixing the materials by a double-screw extruder, and extruding and granulating to obtain the halogen-free flame-retardant low-density polyethylene material.

Specifically, the preparation method of the halogen-free flame-retardant high-density polyethylene material comprises the following steps:

1) feeding HDPE into a double-screw extruder from a main feeding port through a No. 1 weightless weighing bin;

2) compounding a P-N compound flame retardant according to a proportion, adding the compounded flame retardant into a No. 2 weightless scale weighing bin, and adding a flame retardant synergist, an antioxidant and a lubricant into a No. 3 weightless scale weighing bin after compounding the flame retardant synergist, the antioxidant and the lubricant according to the proportion;

3) after materials in the 2# and 3# weightless scales of the storage bins are uniformly mixed in a side feeding conveying bin, the materials are fed into the 4 th to 5 th sections of a screw of a double-screw extruder through a feeding conveying screw;

4) mixing, extruding and granulating by a double-screw extruder to obtain a halogen-free flame-retardant high-density polyethylene material;

5) the extrusion temperature is 180-195 ℃, and the double-screw extruder adopts an independently designed screw combination.

Preferably, in the preparation method of the halogen-free flame-retardant high-density polyethylene material, the step 1) and the step 2) are weightless scales which are quantitative feeding equipment for calculating the material flow rate by using the material reduction rate in unit time, and the flow rate is calculated by adopting an approximate static weighing mode.

More preferably, in the preparation method of the halogen-free flame-retardant high-density polyethylene material, the control systems of the weightless scales in the steps 1) and 2) are controlled by a PLC + human-computer interface or an intelligent instrument, and the state of the scale body can be displayed on the system in real time and has a human-computer interaction interface.

Preferably, in the preparation method of the halogen-free flame-retardant high-density polyethylene material, the weightlessness scale weighing bin in the steps 1) and 2) is provided with a weightlessness scale sensor and a weightlessness scale stirring device.

Preferably, in the preparation method of the halogen-free flame-retardant high-density polyethylene material, the high-precision weightless scale spiral discharging mechanism is adopted in the side feeding conveying bin in the step 3).

Preferably, in the preparation method of the halogen-free flame-retardant high-density polyethylene material, the twin-screw extruder is a co-rotating twin-screw extruder, and the specific parameters are as follows: the diameter of the screw is 70-95 mm, and the length-diameter ratio of the screw is (40-48): 1; further preferred screws have a diameter of 75mm, a screw length to diameter ratio of 44: 1.

preferably, in the preparation method of the halogen-free flame-retardant high-density polyethylene material, in the step 5), the temperature parameters of each zone of the twin-screw extruder are as follows: the 1 st section is 100-115 ℃, the 2 nd to 4 th sections are 180-195 ℃, and the 5 th to 11 th sections are 195-190 ℃.

Preferably, in the preparation method of the halogen-free flame-retardant high-density polyethylene material, the screw combination in the step 5) is designed independently, and 2 groups of toothed disc combinations are arranged between the fifth section of the screw and the head section without shear blocks.

The halogen-free flame-retardant high-density polyethylene material or the halogen-free flame-retardant low-density polyethylene material prepared by the preparation method is applied to non-bearing plastic boxes and garbage cans.

The embodiment of the invention has the beneficial effects

1. According to the halogen-free flame-retardant high-density polyethylene material provided by the embodiment of the invention, the flame retardant property UL94 reaches V-2 level, the mechanical property is excellent, the elongation at break of a workpiece reaches 842%, the workpiece can be recycled, the environment-friendly flame-retardant high-density polyethylene material is environment-friendly and halogen-free, corrosive gas is not generated during combustion, the self-extinguishing property is excellent, and the problems of mechanical property and bromine and antimony flame retardance existing in the halogen-free flame retardant technology of HDPE in the prior art are solved;

2. the embodiment of the invention provides the halogen-free flame-retardant high-density polyethylene material, wherein HDPE of middle injection molding grade is selected as matrix resin, because the embodiment of the invention is mainly applied to plastic boxes and garbage cans, the HDPE is obviously superior to PP in cold resistance, can be used for a long time under the low-temperature condition, and is not easy to influence the service performance of the product due to brittle fracture;

3. the embodiment of the invention provides a halogen-free flame retardantThe high-density polyethylene material is prepared by matching an aluminum hypophosphite flame retardant with a melamine or melamine cyanurate flame retardant to form a P-N compound flame retardant, wherein the aluminum hypophosphite has a synergistic effect on the flame retardant MCA or melamine, and possibly, in the combustion process, the aluminum hypophosphite or diethyl aluminum hypophosphite flame retardant is heated and decomposed to generate PO and PO₂Free radicals can capture active free radicals in gas phase to stop combustion chain reaction, so that a better synergistic effect is formed with MCA or melamine sublimation heat absorption and inert gas isolation layer generation, the P-N compound flame retardant has better flame retardant efficiency, does not generate corrosive gas, belongs to an environment-friendly halogen-free flame retardant, has more advantages compared with antimony bromide flame retardant in price and is a trend of development of flame retardant industry, but P flame retardant or N flame retardant cannot be used independently and has low flame retardant efficiency when used independently;

4. according to the halogen-free flame-retardant high-density polyethylene material provided by the embodiment of the invention, the added flame-retardant synergist is 2, 3-dimethyl-2, 3-diphenylbutane, and due to structural particularity, the stability of C-C bonds among corresponding quaternary carbon atoms is not high, and the C-C bonds are easy to dissociate to form free radicals;

5. the halogen-free flame-retardant high-density polyethylene material provided by the embodiment of the invention uses an antioxidant which is compounded by 4, 4 '-butylidene bis (6-tert-butyl-3-methylphenol) and dioctadecyl pentaerythritol diphosphite, the dioctadecyl pentaerythritol diphosphite has better heat-resistant protection in the processing process and later-stage yellowing-resistant protection, the 4, 4' -butylidene bis (6-tert-butyl-3-methylphenol) has low volatility and high thermal stability, high-temperature processing is not decomposed, and a compound antioxidant system can protect the flame-retardant polyethylene material during processing and later-stage storage;

6. in the preparation method of the halogen-free flame-retardant high-density polyethylene material provided by the embodiment of the invention, the weightlessness scale metering system is quantitative feeding equipment for calculating the material flow by utilizing the material reduction rate in unit time, the flow is calculated by adopting an approximate static weighing mode, so the metering mode is simple, the precision is higher, the weighing system is a very practical metering system, the control system adopts a PLC + human-computer interface or an intelligent instrument for control, the operation is simple, the weighing system is stable and reliable, the scale body state can be displayed on the system in real time, the weighing system has a friendly human-computer interaction interface, the weighing bin is provided with a weightlessness scale sensor and a weightlessness scale stirring device, the design can prevent the impact of the materials and ensure the uniform and smooth feeding while the weighing is met, the feeding is convenient to disassemble when parts are cleaned and replaced by the products, and the volume of the bin can be designed according to the amount, the material in the side feeding conveying bin is conveyed through the weightless scale spiral discharging mechanism, a high-precision screw is adopted to be finely processed to form a small gap between the material and the wall of the bin, so that high weighing precision and feeding stability are ensured, the connection between the speed reducing motor and the screw is compact and simple, the transition link is reduced, the transmission precision is higher, a high-precision weightless scale system is adopted, the metering is accurate, the side feeding conveying bin is suitable for quantitative production, and the product quality is stable;

7. according to the preparation method of the halogen-free flame-retardant high-density polyethylene material provided by the embodiment of the invention, the corresponding screw combination is designed autonomously according to the characteristics of the halogen-free flame-retardant polyethylene material, the product performance is ensured, HDPE is fully plasticized in a machine through 2 groups of shear block combinations from the main feeding part to the side feeding part in the combination, the reverse thread block is added at the front end of the side feeding port, the flow rate of the HDPE in the double screws is reduced, the HDPE and auxiliary agents such as a flame retardant are better converged, the side feeding port is connected to a vacuum port section, the large conveying block is firstly used, the flame retardant discharged from the side feeding conveying bin is ensured to rapidly enter the double screws, then 2 groups of toothed disc combinations are used, the flame retardant is fully mixed with the HDPE, the shearing of the toothed discs is weak, the heat generation of the double screws is reduced.

Drawings

FIG. 1 is a flow chart of a method for preparing a halogen-free flame-retardant high-density polyethylene material according to an embodiment of the invention.

Detailed Description

The present invention will be described in further detail with reference to specific examples. The starting materials used in the examples are, unless otherwise specified, commercially available from conventional sources.

In order to better understand the above technical solutions, the above technical solutions will be described in detail with reference to specific embodiments.