Method for preparing polyethylene / aluminum diethylphosphinate master batch through in-situ graft polymerization

Abstract

The invention relates to a method for preparing polyethylene / aluminum diethylphosphinate master batch by in-situ graft polymerization, which comprises the following steps: silicon coating: diluting aluminum diethylphosphinate into slurry with the concentration of 20-50wt% by using water, adding a sodium hexametaphosphate solution, dispersing at a high speed, heating to 70-90 DEG C, adjusting the pH value of the solution to 7-10, adding a sodium silicate solution and a sulfuric acid solution, keeping the pH value at 7-10, and stirring and curing for 30-60 minutes; the silicon-coated aluminum diethylphosphinate slurry is obtained; silane coupling: adding 0.5-2wt% of emulsified vinyl silane organic coating agent into the silicon-coated aluminum diethylphosphinate slurry obtained in the step S1, stirring, carrying out filter pressing, washing, drying and crushing to obtain silane-treated aluminum diethylphosphinate; and in-situ graft polymerization: adding 80-70wt% of silane-treated aluminum diethylphosphinate, 0.1-1wt% of an initiator, 1-2wt% of polyethylene wax and 18.9-27wt% of polyethylene particles into a high-speed mixer for uniform mixing, adding the mixture into a twin-screw extruder for in-situ graft polymerization, and performing air cooling granulation after extrusion to obtain the in-situ graft polymerized polyethylene / aluminum diethylphosphinate master batch.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant modification of plastics, and specifically to a method for preparing a polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization. Background Art

[0002] With the advancement of science and technology and the improvement of living standards, plastics, rubber, etc. are becoming more and more important in people's lives, and their applications are expanding year by year. However, most plastics and rubber materials are flammable to varying degrees in the air. In order to achieve applications in many industries such as military, aerospace, transportation, electricity and civil use, plastics and rubber products are flame-retardant modified. At present, the commonly used flame-retardant modification method is to improve the fire resistance of plastics and rubber by adding flame retardants or flame-retardant masterbatches.

[0003] According to the classification of flame retardant elements, flame retardants can usually be divided into halogen, phosphorus, antimony, magnesium, boron, and molybdenum series. Halogen series are further divided into chlorine and bromine series. Bromine-based flame retardants are recognized as the most effective flame retardants with wide applicability, easy use, excellent flame retardant effect, and high flame retardant efficiency for most plastics. However, when a fire occurs, this type of bromine-containing flame retardant material will produce a large amount of smoke and toxic and corrosive hydrogen halide gas, causing secondary hazards. At present, halogen-free flame retardant materials have been gradually promoted in many flame retardant application fields. Halogen-free flame retardants are mainly phosphorus-nitrogen compounds and metal hydroxides. The flame-retardant plastics produce little smoke when burned and do not produce toxic, harmful or corrosive gases. They are called pollution-free flame retardants and have become the direction of future plastic flame retardant technology development.

[0004] Aluminum diethylphosphinate is a safe and efficient phosphorus-based flame retardant and a major component of the intumescent halogen-free flame retardant system. It is widely used in the halogen-free flame retardant modification of various high-value-added plastics. However, the pH value of aluminum diethylphosphinate is 4.3, which is slightly acidic. Direct use will corrode processing equipment and cause resin degradation. In addition, aluminum diethylphosphinate also has problems such as low fluidity, poor dispersibility, and poor interfacial adhesion with the modified polymer during its application, which leads to a decrease in the mechanical properties and flame retardant properties of the material.

[0005] Aluminum diethylphosphinate and related flame retardant synergists, such as nitrogen-based flame retardants and carbon-forming agents, are generally powders and are added in large quantities. When a twin-screw extruder is directly used for melt extrusion blending, it is difficult to fully mix the polymer melt with the flame retardant due to the limited residence time of the material in the barrel of the extruder. Since a large amount of flame retardant powders generate internal heat due to mechanical friction between each other during the blending and extrusion process, it will not only cause the flame retardant to decompose and damage the flame retardant effect, but also cause the physical and mechanical properties of the modified engineering plastics to decrease.

[0006] Therefore, it is necessary to provide a method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization to solve the above problems. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization.

[0008] The present invention achieves the above object through the following technical solutions:

[0009] A method for preparing a polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization comprises the following steps:

[0010] S1) Silicon coating: dilute aluminum diethylphosphinate with water to a slurry with a concentration of 20-50wt%, add a sodium hexametaphosphate solution in a weight ratio of P205 to aluminum diethylphosphinate of 0.1-0.5:100 to the slurry, disperse at high speed for 30-60min, heat to 70-90°C, adjust the pH value of the solution to 7-10 with sodium hydroxide, add sodium silicate solution and sulfuric acid solution in a weight ratio of Si: aluminum diethylphosphinate = 0.5-2:100, the molar ratio of the sodium silicate solution to the sulfuric acid solution is 1:1, keep the pH value between 7 and 10, stir and mature for 30-60min; obtain silicon-coated aluminum diethylphosphinate slurry;

[0011] S2) Silane coupling: adding 0.5-2 wt% of the emulsified vinyl silane organic coating agent to the silicon-coated aluminum diethylphosphinate slurry obtained in S1, stirring for 40 minutes, filtering, washing with water, drying and crushing to obtain silane-treated aluminum diethylphosphinate;

[0012] S3) In-situ graft polymerization: 80-70 wt% of silane-treated aluminum diethylphosphinate, 0.1-1 wt% of initiator, 1-2 wt% of polyethylene wax and 18.9-27 wt% of polyethylene particles are added into a high-speed mixer and mixed evenly, beaten into sandy shape, and then added into a twin-screw extruder for in-situ graft polymerization. After extrusion, air cooling and granulation are performed to obtain an in-situ graft polymerization polyethylene / aluminum diethylphosphinate masterbatch.

[0013] Further, the reaction mechanism of S1) can be expressed by the chemical equation:

[0014] Na 2 SiO 3 +H 2 S0 4 +(n-1)H 2 0=Si0 2 ·nH 2 O↓+3Na 2 S0 4 ;

[0015] Further, the reaction mechanism of S2) can be expressed by the chemical equation:

[0016]

[0017] Further, the reaction mechanism of S3) can be expressed by the chemical equation:

[0018] RO-OR→2RO

[0019] -(CH 2 -CH 2 -CH 2 ) n -+RO·→-(CH 2 -CH-CH 2 ) n -+ROH

[0020] -(CH 2 -CH-CH 2 ) n -+CH 2 =CH-Si(OR) 3 →-(CH 2 -CH-CH 2 ) n -

[0021] ∣CH 2 -CH-Si(OR) 3 .

[0022] Furthermore, the vinyl silane is one or more of vinyl trimethoxy silane, vinyl triethoxy silane and vinyl tri-β-methoxyethoxy silane.

[0023] Furthermore, the initiator is benzoyl peroxide and / or dicumyl peroxide.

[0024] Furthermore, the polyethylene particles are one or more of high-density polyethylene, low-density polyethylene, linear polyethylene and metallocene polyethylene.

[0025] Furthermore, the drying is carried out by flash drying.

[0026] Furthermore, the pulverization adopts air flow pulverization method.

[0027] Compared with the prior art, the method of preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization of the present invention adopts the process of silane coupling and in-situ graft polymerization, so that aluminum diethylphosphinate and polyethylene become an organic whole, which solves the dispersion problem of aluminum diethylphosphinate in polyethylene masterbatch and avoids the decrease of mechanical properties of plastic products after using flame retardant masterbatch; at the same time, the process of coating the surface of aluminum diethylphosphinate with silicon dioxide solves the acidity problem of aluminum diethylphosphinate and reduces the corrosion of processing equipment. Making aluminum diethylphosphinate into masterbatch also solves the dust problem of powder, the stratification and feeding problem of powder, and the fluidity problem of flame retardant powder. This preparation process does not need to add small molecule coupling agents and lubricants, improves the flame retardant efficiency, and improves the mechanical properties of flame retardant materials. DETAILED DESCRIPTION

[0028] Embodiment 1:

[0029] The method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization comprises the following steps:

[0030] S1, silicon coating: dilute aluminum diethylphosphinate with water to a slurry with a concentration of 20wt%, add sodium hexametaphosphate solution in a weight ratio of P205 to aluminum diethylphosphinate of 0.1:100 to the slurry, disperse at high speed for 30 minutes, heat to 70°C, adjust the solution pH to 7 with sodium hydroxide, add sodium silicate solution and sulfuric acid solution in a weight ratio of Si: aluminum diethylphosphinate = 0.5:100, the molar ratio of sodium silicate solution to sulfuric acid solution is 1:1, keep the pH value between 7, stir and mature for 30 minutes; obtain silicon-coated aluminum diethylphosphinate slurry;

[0031] S2, silane coupling: add 0.5wt% of the emulsified vinyl silane organic coating agent to the silicon-coated aluminum diethylphosphinate slurry obtained in S1, stir for 40 minutes, filter press, wash with water, dry and grind to obtain silane-treated aluminum diethylphosphinate;

[0032] S3, in-situ graft polymerization: 80wt% of silane-treated aluminum diethylphosphinate, 0.1wt% of initiator, 1wt% of polyethylene wax and 18.9wt% of polyethylene particles are added into a high-speed mixer and mixed evenly, beaten into sandy form, and then added into a twin-screw extruder for reaction. After extrusion, the mixture is air-cooled and granulated to obtain an in-situ grafted polyethylene / aluminum diethylphosphinate masterbatch.

[0033] Embodiment 2:

[0034] The method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization comprises the following steps:

[0035] S1, silicon coating: dilute aluminum diethylphosphinate with water to a slurry with a concentration of 50 wt%, add P 2 0 5 A sodium hexametaphosphate solution having a weight ratio of 0.5:100 to aluminum diethylphosphinate is dispersed at high speed for 60 minutes, the temperature is raised to 90°C, the pH value of the solution is adjusted to 10 with sodium hydroxide, a sodium silicate solution and a sulfuric acid solution are added at a weight ratio of Si: aluminum diethylphosphinate = 2:100, the molar ratio of the sodium silicate solution to the sulfuric acid solution is 1:1, the pH value is maintained between 10, and the mixture is stirred and aged for 60 minutes; a silicon-coated aluminum diethylphosphinate slurry is obtained;

[0036] S2, silane coupling: add 2 wt% of the emulsified vinyl silane organic coating agent to the silicon-coated aluminum diethylphosphinate slurry obtained in S1, stir for 40 minutes, filter press, wash with water, dry and grind to obtain silane-treated aluminum diethylphosphinate;

[0037] S3, in-situ graft polymerization: 70wt% of silane-treated aluminum diethylphosphinate, 1wt% of initiator, 2wt% of polyethylene wax and 27wt% of polyethylene particles are added into a high-speed mixer and mixed evenly, beaten into sandy form, and then added into a twin-screw extruder for reaction. After extrusion, the mixture is air-cooled and granulated to obtain an in-situ grafted polyethylene / aluminum diethylphosphinate masterbatch.

[0038] In Example 1 and Example 2:

[0039] The reaction mechanism of S1) can be expressed by the chemical equation:

[0040] Na 2 SiO 3 +H 2 S0 4 +(n-1)H 2 0=Si0 2 ·nH 2 O↓+3Na 2 S0 4 ;

[0041] The reaction mechanism of S2) can be expressed by the chemical equation:

[0042]

[0043] S3) The reaction mechanism can be expressed by the chemical equation:

[0044] RO-OR→2RO

[0045] -(CH 2 -CH 2 -CH 2 ) n -+RO·→-(CH 2-CH-CH 2 ) n -+ROH

[0046] -(CH 2 -CH-CH 2 ) n -+CH 2 =CH-Si(OR) 3 →-(CH 2 -CH-CH 2 ) n -

[0047] ∣CH 2 -CH-Si(OR) 3 .

[0048] and:

[0049] The vinyl silane is one or more of vinyl trimethoxy silane, vinyl triethoxy silane and vinyl tri-β-methoxyethoxy silane.

[0050] The initiator is benzoyl peroxide and / or dicumyl peroxide.

[0051] The polyethylene particles are one or more of high-density polyethylene, low-density polyethylene, linear polyethylene and metallocene polyethylene.

[0052] The drying is carried out by flash drying.

[0053] The crushing adopts the air flow crushing method.

[0054] Compared with the prior art, the method of preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization of the present invention adopts the process of silane coupling and in-situ graft polymerization, so that aluminum diethylphosphinate and polyethylene become an organic whole, which solves the dispersion problem of aluminum diethylphosphinate in polyethylene masterbatch and avoids the decrease of mechanical properties of plastic products after using flame retardant masterbatch; at the same time, the process of coating the surface of aluminum diethylphosphinate with silicon dioxide solves the acidity problem of aluminum diethylphosphinate and reduces the corrosion of processing equipment. Making aluminum diethylphosphinate into masterbatch also solves the dust problem of powder, the stratification and feeding problem of powder, and the fluidity problem of flame retardant powder. This preparation process does not need to add small molecule coupling agents and lubricants, improves the flame retardant efficiency, and improves the mechanical properties of flame retardant materials.

[0055] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization, characterized in that: The following steps are involved: S1) Silicon coating: dilute aluminum diethylphosphinate with water to a slurry with a concentration of 20-50wt%, add a sodium hexametaphosphate solution in a weight ratio of P205 to aluminum diethylphosphinate of 0.1-0.5:100 to the slurry, disperse at high speed for 30-60min, heat to 70-90°C, adjust the pH value of the solution to 7-10 with sodium hydroxide, add sodium silicate solution and sulfuric acid solution in a weight ratio of Si: aluminum diethylphosphinate = 0.5-2:100, the molar ratio of the sodium silicate solution to the sulfuric acid solution is 1:1, keep the pH value between 7 and 10, stir and mature for 30-60min; obtain silicon-coated aluminum diethylphosphinate slurry; S2) Silane coupling: adding 0.5-2 wt% of the emulsified vinyl silane organic coating agent to the silicon-coated aluminum diethylphosphinate slurry obtained in S1, stirring for 40 minutes, filtering, washing with water, drying and crushing to obtain silane-treated aluminum diethylphosphinate; S3) In-situ graft polymerization: 80-70 wt% of silane-treated aluminum diethylphosphinate, 0.1-1 wt% of initiator, 1-2 wt% of polyethylene wax and 18.9-27 wt% of polyethylene particles are added into a high-speed mixer and mixed evenly, beaten into sandy shape, and then added into a twin-screw extruder for in-situ graft polymerization. After extrusion, air cooling and granulation are performed to obtain an in-situ graft polymerization polyethylene / aluminum diethylphosphinate masterbatch.

2. The method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization according to claim 1, characterized in that: The reaction mechanism of S1) can be expressed by the chemical equation: Na2Si03+H2S04+(n-1)H20=Si02·nH2O↓+3Na2S04.

3. The method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization according to claim 2, characterized in that: The reaction mechanism of S2) can be expressed by the chemical equation:

4. The method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization according to claim 3, characterized in that: S3) The reaction mechanism can be expressed by the chemical equation: RO-OR→2RO . -(CH2-CH2-CH2) n -+RO . →-(CH2-CH-CH2) n -+ROH -(CH2-CH-CH2) n -+CH2=CH-Si(OR)3→-(CH2-CH-CH2) n - |CH2-CH-Si(OR)3.

5. The method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization according to claim 4, characterized in that: The vinyl silane is one or more of vinyl trimethoxy silane, vinyl triethoxy silane and vinyl tri-β-methoxyethoxy silane.

6. The method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization according to claim 5, characterized in that: The initiator is benzoyl peroxide and / or dicumyl peroxide.

7. The method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization according to claim 6, characterized in that: The polyethylene particles are one or more of high-density polyethylene, low-density polyethylene, linear polyethylene and metallocene polyethylene.

8. The method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization according to claim 7, characterized in that: The drying is carried out by flash drying.

9. The method for preparing polyethylene / aluminum diethylphosphinate masterbatch by in-situ graft polymerization according to claim 8, characterized in that: The crushing adopts the air flow crushing method.

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