Preparation method of chlorinated polyethylene

Abstract

The invention relates to the technical field of polyethylene preparation, and discloses a chlorinated polyethylene preparation method, a solvent adopts carbon tetrachloride for dissolving polyethylene, the polyethylene with the added carbon tetrachloride is 1 part, the size diameter is 0.1 [mu] m-300 [mu] m, and the ratio of the polyethylene to the carbon tetrachloride in parts by mass is 1: 3; 1: 5; and mixing and stirring at 1: 7 and 1: 9. According to the invention, in the two intervals of 60-80 DEG C and 80-100 DEG C, the dissolution time is reduced along with the increase of the external temperature; as the temperature is continuously increased to the range of 100-110 DEG C, the time required for dissolving polyethylene in carbon tetrachloride is reduced, but the energy consumption in the range of 100-110 DEG C is increased and is not in direct proportion to the used time, so that the dissolving temperature can be controlled in the range of 80-100 DEG C in the process of accelerating dissolving, and the dissolving speed is increased. And high dissolution efficiency can be obtained in the interval.

Description

Technical Field

[0001] The invention relates to the technical field of polyethylene preparation, in particular to a method for preparing chlorinated polyethylene. Background Art

[0002] Chlorinated polyethylene is an important polymer material, which is made from polyethylene (PE) through chlorination reaction. Chlorine atoms are introduced into its molecular structure, which gives the material excellent weather resistance, chemical corrosion resistance, flame retardancy and other properties. In recent years, with the improvement of environmental protection requirements and technological progress, the traditional suspension method, that is, suspending polyethylene particles in water, adding initiators and chlorine gas for reaction. This method is simple in process, but the traditional method has problems such as low reaction efficiency, poor product uniformity, and environmental pollution. At the same time, it is difficult to accurately control the reaction conditions (such as temperature, pressure, chlorine concentration, etc.), resulting in unstable product performance. Therefore, it is necessary to analyze the data on pressure and temperature to obtain the optimal method for preparing chlorinated polyethylene.

[0003] Therefore, we designed a method for preparing chlorinated polyethylene. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the reaction conditions (such as temperature, pressure, chlorine concentration, etc.) are difficult to accurately control, resulting in unstable product performance, and to propose a method for preparing chlorinated polyethylene.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing chlorinated polyethylene includes the following raw material components: polyethylene, chlorine, a solvent and an initiator, and the specific steps are as follows: S1: adding the polyethylene to a solvent and heating it until dissolved to obtain product A; S2: stirring product A under heating and pressurizing environment and introducing 15% chlorine gas, wherein the chlorine concentration is the volume ratio of chlorine gas to air, the chlorine flow rate ranges from 3L / min to 5L / min, wherein the heating temperature ranges from 60°C to 110°C, and the atmospheric pressure environment ranges from 1atm to 1.65atm, to obtain product B; S3: adding an initiator and a surfactant to the product B to obtain a suspension of an ethylene polymer, and introducing chlorine gas at a concentration of 15% by volume to obtain a product C; S4: Stop the chlorine gas flow and cool the mixture, filter the product C, wash it, and dry it at 50°C-80°C to obtain chlorinated polyethylene.

[0006] Preferably, the solvent in S1 is carbon tetrachloride, which is used to dissolve polyethylene. The amount of polyethylene added to carbon tetrachloride is 1 part, and the diameter is 0.1 μm-300 μm. The mixture is mixed and stirred in a mass ratio of carbon tetrachloride to polyethylene in the range of 3-9. The reaction time in S1 is controlled within a range that the polymer particles do not change color, and the reaction time range is 3 min-5 min.

[0007] Preferably, the flow rate of chlorine gas introduced into S2 is in the range of 3 L / min-5 L / min, wherein the reaction temperature in S3 is in the range of 110° C.-170° C.

[0008] Preferably, the heating temperature in S2 is in the range of 60°C-110°C; The atmospheric pressure environment ranges from 1atm to 1.65atm.

[0009] Preferably, the initiator in S3 comprises a dimethyl sulfoxide solution, wherein the concentration of the dimethyl sulfoxide solution is 1%-20%; The surfactant includes a quaternary ammonium salt, wherein the concentration of the quaternary ammonium salt is 2.5%-10%.

[0010] Preferably, the reaction time of introducing chlorine gas in S3 ranges from 30 min to 125 min.

[0011] Preferably, the product B in the S3 is gradually heated from 110° C. to 170° C., an initiator and a surfactant are added to generate a suspension of an ethylene polymer, and chlorine is continuously introduced into the S3 to keep the ethylene polymer in an active state.

[0012] Preferably, the temperature drop range after the reaction in S4 is 70°C-110°C, and the temperature drop range for washing and drying in S4 is 50°C-80°C.

[0013] Preferably, the suspension of ethylene polymer prepared in S3 contains α-olefin copolymer with 3-8 carbon atoms, and the molar ratio of α-olefin copolymer to ethylene polymer is greater than 1:20, and the density of α-olefin copolymer is 0.93-0.97 g / cm³, the particle size distribution of α-olefin copolymer is 0.1-300 μm, and the porosity of α-olefin copolymer is greater than 0.15 cm³ / g, and chlorinated polyethylene is prepared The specific surface area of ​​the material is greater than 1㎡ / g .

[0014] Preferably, in S3, the reaction temperature ranges from 110°C to 170°C, the ethylene polymer is chlorinated to 10%-20%, then at 150°C, the reaction time is 2 minutes to increase the chlorination degree of the ethylene polymer, and finally the product C is cooled to 110°C.

[0015] The beneficial effects of the present invention are: 1. In the present invention, in the two intervals of 60°C-80°C and 80°C-100°C, the dissolution time will decrease as the external temperature increases; however, as the temperature continues to rise to the interval of 100°C-110°C, the time required for polyethylene to dissolve in carbon tetrachloride decreases, but the energy consumption in the interval of 100°C-110°C increases, which is not proportional to the time used. Therefore, in the process of accelerating dissolution, the dissolution temperature can be controlled in the interval of 80°C-100°C, and a higher dissolution efficiency can be obtained in this interval.

[0016] 2. The present invention adopts that under the same heating environment, as the flow rate of chlorine gas increases, the required reaction time will be reduced accordingly. For example, in the temperature range of 110°C-130°C, that is, at a chlorine gas flow rate of 3L / min-4.5L / min, as the flow rate increases, the time from the start of preparing chlorinated polyethylene to the completion of preparing chlorinated polyethylene decreases successively. At this time, as the chlorine gas flow rate continues to increase and reaches 4.5L / min or more, the time used for preparing chlorinated polyethylene no longer decreases with the increase of chlorine gas flow rate. At the same time, compared with the temperature in the range of 130°C-150°C, the chlorine gas flow rate is reduced, but the time for preparing chlorinated polyethylene is still 2.0min. It can be obtained that as the temperature increases and the chlorine gas flow rate increases, the time for preparing chlorinated polyethylene will be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention provides a flow chart of a method for preparing chlorinated polyethylene. DETAILED DESCRIPTION

[0018] Reference Figure 1 , Embodiment 1 A method for preparing chlorinated polyethylene. The method used in this application document is an aqueous suspension method, which is a method of suspending polyethylene powder in an aqueous medium for chlorination. The process reaction is relatively stable and easy to control. The product is usually a white powder, which is convenient for storage, transportation and use. Therefore, it is the most important method in current industrial production. The materials required in the preparation process include the following raw material components: polyethylene, chlorine, solvent and initiator. The specific steps are as follows: S1: adding the polyethylene to a solvent and heating it until dissolved to obtain product A; S2: Stir product A under heating and pressurizing environment and introduce chlorine gas, the chlorine gas flow rate range is 3L / min-5L / min, the chlorine gas concentration is 15% (volume fraction), the heating temperature range is 60℃-110℃, the atmospheric pressure environment range is 1atm-1.65atm, and product B is obtained; S3: adding an initiator and a surfactant to the product B to obtain a suspension of an ethylene polymer, and introducing chlorine gas to obtain a product C; S4: Stop the chlorine gas flow and cool the mixture, filter the product C, wash it, and dry it at 50°C-80°C to obtain chlorinated polyethylene.

[0019] The suspension of ethylene polymer prepared in S3 contains α-olefin copolymer with 3-8 carbon atoms, and the molar ratio of α-olefin copolymer to ethylene polymer is greater than 1:20, and the density of α-olefin copolymer is 0.93-0.97 g / cm³, the particle size distribution of α-olefin copolymer is 0.1-300 μm, the porosity of α-olefin copolymer is greater than 0.15 cm³ / g, and the specific surface area of ​​the material for preparing chlorinated polyethylene is greater than 1 m2 / g.

[0020] Embodiment 2 It should be noted that the solvent in S1 is carbon tetrachloride, which is used to dissolve polyethylene. The amount of polyethylene added to carbon tetrachloride is 1 part, and the diameter is 0.1 μm-300 μm. The polyethylene and carbon tetrachloride are mixed and stirred in four mass ratios of 1:3, 1:5, 1:7 and 1:9. The reaction time in S1 is controlled within the range of not causing the polymer particles to change color. The reaction time range is 3 min-5 min, and protective equipment is worn in a well-ventilated environment. The following records are made for the mixing of different mass ratios: (1) Select the ratio of 1:3, that is, 1 part of polyethylene and 3 parts of carbon tetrachloride; Dissolution: Polyethylene partially dissolves in carbon tetrachloride to form a turbid solution with a solubility of 43.2%.

[0021] (2) Select a ratio of 1:5, i.e. 1 part polyethylene and 5 parts carbon tetrachloride; Dissolution: The solubility is improved and the solution is more uniform, but there are still a small amount of undissolved polyethylene particles. The degree of dissolution is 79.6%.

[0022] (3) Select a ratio of 1:7, i.e. 1 part polyethylene and 7 parts carbon tetrachloride; Dissolution: Polyethylene is almost completely dissolved, the solution is transparent, without obvious particles, and the degree of dissolution is 94.6%.

[0023] (4) Select a ratio of 1:9, i.e. 1 part polyethylene and 9 parts carbon tetrachloride; Dissolution: Polyethylene is completely dissolved, the solution is very transparent, no particles remain, and the dissolution degree is 99.6%.

[0024] Summary: The solubility increases with the increase of carbon tetrachloride ratio. At the ratio of 1:7 and 1:9, polyethylene is almost completely dissolved and the solution is transparent.

[0025]

[0026] Table 1 The solubility increases with the increase of carbon tetrachloride ratio. At the ratio of 1:7 and 1:9, polyethylene is almost completely dissolved and the solution is transparent. Therefore, the mixing ratio of polyethylene to carbon tetrachloride by mass of 1:7 and 1:9 is selected.

[0027] Embodiment 3 It should be noted that: the heating dissolution temperature of 60℃-110℃ in S2 is divided into three intervals, namely 60℃-80℃, 80℃-100℃ and 100℃-110℃. The heating process of 60℃-110℃ adopts a slow heating method. The time required for polyethylene to dissolve in carbon tetrachloride is recorded as follows;

[0028] Table 2 It can be seen from the table that in the two ranges of 60℃-80℃ and 80℃-100℃, the dissolution time will decrease as the external temperature increases; but as the temperature continues to rise to the range of 100℃-110℃, the time required for polyethylene to dissolve in carbon tetrachloride will decrease, but the energy consumption in the range of 100℃-110℃ increases, which is not proportional to the time used. Therefore, in the process of accelerating dissolution, the dissolution temperature can be controlled in the range of 80℃-100℃, and a higher dissolution efficiency will be obtained in this range.

[0029] At the same time, during the dissolution process, the atmospheric pressure environment is divided into four intervals: 1atm-1.05atm; 1.05atm-1.25atm; 1.25atm-1.45atm and 1.45atm-1.65atm. Dissolution is carried out at the same temperature (in the temperature range of 80℃-100℃), and the dissolution time in the four intervals is recorded:

[0030] Table 3 It can be concluded that the time required for polyethylene to dissolve in carbon tetrachloride under an atmospheric pressure environment of 1atm-1.05atm is longer than the time required for polyethylene to dissolve in carbon tetrachloride under an atmospheric pressure environment of 1.05atm-1.25atm. Subsequently, as the atmospheric pressure increases, the time required for polyethylene to dissolve in carbon tetrachloride no longer changes under atmospheric pressure environments of 1.25atm-1.45atm and 1.45atm-1.65atm. Therefore, in the initial preparation stage of the reaction, the dissolution environment pressure needs to be adjusted to slightly greater than a standard atmospheric pressure, that is, to 1.05atm-1.25atm, and then subsequent operations are carried out.

[0031] When the dissolution is completed, the corresponding chlorine inlet tube is inserted into the bottom of the carbon tetrachloride container containing dissolved polyethylene, and then chlorine is introduced. This part of the chlorine will be discharged from the chlorine inlet tube and move upward from the bottom of the container, while reacting with the polyethylene dissolved in the carbon tetrachloride.

[0032] In the temperature range between 110℃-170℃, chlorination is carried out to 10%-20%, then, at 150℃, the chlorination degree is increased to a predetermined level, and finally the temperature is lowered to 110℃.

[0033] Embodiment 4 The chlorine gas flow rates introduced into S2 are 3 L / min, 3.5 L / min, 4 L / min; 4.5 L / min and 5 L / min respectively.

[0034] It should be noted that when polyethylene is added into carbon tetrachloride in proportion and stirred, the ambient temperature of the stirring place needs to be maintained at 60°C-110°C, so the stirring environment needs to be slowly heated from room temperature to 60°C-110°C.

[0035] Furthermore, during the stirring and heating process, the temperature usually needs to be raised to 110°C. In the temperature range of 60°C-110°C, as the temperature rises, the solubility of polyethylene in carbon tetrachloride becomes higher, until the polyethylene in carbon tetrachloride is completely dissolved, which facilitates the subsequent introduction of chlorine gas, so that the chlorine gas fully reacts with the polyethylene in carbon tetrachloride to avoid the formation of polyethylene. The specific reaction chemical formula is as follows:

[0036] in Represents polyethylene, Chlorinated polyethylene, For chlorine, It is hydrogen chloride.

[0037] Therefore, polyethylene will be reacted with chlorine to produce chlorinated polyethylene. At the same time, the generated hydrogen chloride will not be absorbed and dissolved by carbon tetrachloride, so it will not affect the generated chlorinated polyethylene.

[0038] The flow rate of chlorine gas is 3L / min, 3.5L / min, 4L / min, 4.5L / min and 5L / min, and the four flow rates are 3L / min, 3.5L / min, 4L / min, 4.5L / min and 5L / min respectively. The four types of chlorine flow rates are introduced into the carbon tetrachloride in which the polyethylene is almost completely dissolved, and the reaction is ensured to be within the range of 110°C-170°C during the introduction process. It should be noted that the four types of flow rates are introduced into the same ambient temperature for reaction preparation. The time taken from the start of preparation of chlorinated polyethylene to the completion of preparation of chlorinated polyethylene is the reaction temperature range of S3 from 110°C to 170°C, and the reaction temperature is divided into three intervals: 110°C-130°C, 130°C-150°C and 150°C-170°C, thereby obtaining the following data:

[0039] Table 4 The following conclusions can be drawn from this data: (1) Under the same heating environment, as the flow rate of chlorine gas increases, the required reaction time will decrease accordingly. For example, in the temperature range of 110℃-130℃, that is, at a chlorine gas flow rate of 3L / min-4.5L / min, as the flow rate increases, the time from the start of preparing chlorinated polyethylene to the completion of preparing chlorinated polyethylene decreases successively. At this time, as the chlorine gas flow rate continues to increase and reaches more than 4.5L / min, the time for preparing chlorinated polyethylene no longer decreases with the increase of chlorine gas flow rate, and reaches 2.8min.

[0040] (2) In the temperature range of 130℃-150℃, at a chlorine gas flow rate of 3L / min-5L / min, as the flow rate increases, the time from the start of the preparation of chlorinated polyethylene to the completion of the preparation of chlorinated polyethylene decreases and reaches 2.0min. Therefore, combined with conclusion (1), it can be obtained that at the same chlorine gas flow rate, as the temperature increases, the time for preparing chlorinated polyethylene decreases. At the same time, the temperature setting is also the threshold for preparing chlorinated polyethylene, which is the shortest reaction time, and the shortest time is 2.0min.

[0041] (3) In the temperature range of 150℃-170℃, at a chlorine gas flow rate of 3L / min-4L / min, as the flow rate increases, the time from the start of preparing chlorinated polyethylene to the completion of preparing chlorinated polyethylene decreases successively and reaches 2.0min. As the chlorine gas flow rate continues to increase, the reaction time does not continue to decrease. Therefore, in the temperature range of 130℃-150℃, the chlorine gas flow rate is 5L / min, and the time for preparing chlorinated polyethylene is 2.0min. As the temperature continues to rise, the time for preparing chlorinated polyethylene does not decrease, but the chlorine gas flow rate is 4L / min. Compared with the temperature range of 130℃-150℃, the chlorine gas flow rate decreases, but the time for preparing chlorinated polyethylene is still 2.0min. Therefore, as the temperature increases and the chlorine gas flow rate increases, the time for preparing chlorinated polyethylene will be reduced. Therefore, at 150℃, the reaction time is 2min, which increases the degree of chlorination of the ethylene polymer, and finally the product C is cooled to 110℃.

[0042] Therefore, in order to meet the needs of preparing chlorinated polyethylene, a chlorine gas flow rate of 5 L / min is usually used under a temperature environment of 130°C-150°C; and under a temperature environment of 150°C-170°C, a chlorine gas flow rate of 4 L / min is used.

[0043] Embodiment 5 S3: adding initiator and surfactant, and adjusting chlorine gas flow rate and temperature; In S3, the initiator comprises a dimethyl sulfoxide solution, wherein the concentration of the dimethyl sulfoxide solution is 1%-20%, and the surfactant is used to prevent the accumulation of static charge, and the surfactant comprises a quaternary ammonium salt, wherein the concentration of the quaternary ammonium salt is 2.5%-10%.

[0044] Embodiment 6 In S3, under the same chlorine gas flow rate and reaction temperature conditions, the reaction time is set to 30min-125min, and is divided into seven time intervals: 30min-45min; 45min-60min; 60min-75min; 75min-90min; 90min-105min; 105min-120min and 120min-125min, and the data of the generated chlorinated polyethylene are recorded in the following table:

[0045] Table 5 It can be seen from the above table that, under the conditions of ensuring the optimal chlorine gas flow rate and reaction temperature, as the reaction time increases, within the range of 30min-105min, more chlorinated polyethylene is generated as time goes by, but within the time of 105min-120min, no excess chlorinated polyethylene is generated, and at the same time within the time range of 120min-125min, the content of chlorinated polyethylene generated decreases, that is, by-products are generated, and the originally generated chlorinated polyethylene is reacted again, thereby resulting in a decrease in the content of chlorinated polyethylene generated.

[0046] Embodiment 7 The temperature drop range after the reaction in S4 is 70°C-110°C. The temperature drop range after washing in S4 is divided into three intervals: 50°C-60°C, 60°C-70°C and 70°C-80°C. Observe whether the cooling process has any effect on the generated chlorinated polyethylene, and record the observation in the following table:

[0047] Table 6 It can be seen from the above table that cooling after washing has almost no effect on the generated chlorinated polyethylene.

[0048] It can be obtained that the method for preparing chlorinated polyethylene is as follows: S1: Select polyethylene and carbon tetrachloride in a mixing ratio of 1:7 and 1:9 by mass, add polyethylene into carbon tetrachloride solvent, heat to 80°C-100°C and dissolve, and obtain product A.

[0049] S2: stirring and introducing chlorine gas at a temperature of 80°C-100°C and an environment of 1.05atm-1.25atm to obtain product B; S3: Add initiator dimethyl sulfoxide solution and surfactant to product B, and adjust the chlorine flow rate to adjust the temperature to react and prepare; S4: stop passing chlorine gas and cool, chlorinate the ethylene polymer to 10%-20%, then react at 150°C for 2 minutes to increase the degree of chlorination of the ethylene polymer, and finally cool the product C to 110°C, filter the product B, wash and dry at 50°C-80°C to obtain chlorinated polyethylene.

[0050] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing chlorinated polyethylene, comprising the following raw material components: polyethylene, chlorine, a solvent and an initiator, characterized in that: The specific steps are as follows: S1: adding the polyethylene to a solvent and heating it until dissolved to obtain product A; S2: stirring product A under heating and pressurizing environment and introducing 15% chlorine gas, wherein the chlorine concentration is the volume ratio of chlorine gas to air, the chlorine flow rate ranges from 3L / min to 5L / min, wherein the heating temperature ranges from 60°C to 110°C, and the atmospheric pressure environment ranges from 1atm to 1.65atm, to obtain product B; S3: adding an initiator and a surfactant to the product B to obtain a suspension of an ethylene polymer, and introducing chlorine gas at a concentration of 15% by volume to obtain a product C; S4: Stop the chlorine gas flow and cool the mixture, filter the product C, wash it, and dry it at 50°C-80°C to obtain chlorinated polyethylene.

2. The method for preparing chlorinated polyethylene according to claim 1, characterized in that: The solvent in S1 is carbon tetrachloride, which is used to dissolve polyethylene. The amount of polyethylene added to carbon tetrachloride is 1 part, and the diameter is 0.1 μm-300 μm. The carbon tetrachloride and polyethylene are mixed and stirred in a mass ratio of 3-9. The reaction time in S1 is controlled within a range that the polymer particles do not change color, and the reaction time range is 3 min-5 min.

3. The method for preparing chlorinated polyethylene according to claim 1, characterized in that: The reaction temperature in S3 is in the range of 110°C to 170°C.

4. The method for preparing chlorinated polyethylene according to claim 1, characterized in that: The initiator in S3 includes a dimethyl sulfoxide solution, wherein the concentration of the dimethyl sulfoxide solution is 1%-20%; The surfactant includes a quaternary ammonium salt, wherein the concentration of the quaternary ammonium salt is 2.5%-10%.

5. The method for preparing chlorinated polyethylene according to claim 1, characterized in that: The reaction time range of introducing chlorine gas in S3 is 30 min-125 min.

6. The method for preparing chlorinated polyethylene according to claim 1, characterized in that: The product B in the S3 is gradually heated from 110° C. to 170° C., and an initiator and a surfactant are added to generate a suspension of an ethylene polymer. Chlorine gas is continuously introduced into the S3 to keep the ethylene polymer in an active state.

7. The method for preparing chlorinated polyethylene according to claim 1, characterized in that: The temperature drop range of the S4 after the reaction is 70°C-110°C, and the temperature drop range of the washing and drying in the S4 is 50°C-80°C.

8. The method for preparing chlorinated polyethylene according to claim 1, characterized in that: The suspension of ethylene polymer prepared in S3 contains α-olefin copolymer with 3-8 carbon atoms, and the molar ratio of α-olefin copolymer to ethylene polymer is greater than 1:20, and the density of α-olefin copolymer is 0.93-0.97g / cm³, the particle size distribution of α-olefin copolymer is 0.1-300μm, the porosity of α-olefin copolymer is greater than 0.15cm³ / g, and the specific surface area of ​​the material for preparing chlorinated polyethylene is greater than 1㎡ / g.

9. The method for preparing chlorinated polyethylene according to claim 1, characterized in that: In the S3, the reaction temperature ranges from 110°C to 170°C, the ethylene polymer is chlorinated to 10%-20%, and then at 150°C, the reaction time is 2 minutes to increase the chlorination degree of the ethylene polymer, and finally the product C is cooled to 110°C.

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