Method for preparing oxidation modified polyethylene wax by using carbon dioxide

Abstract

The invention discloses a process method for oxidation modification of polyethylene wax, the process method can reduce production cost and is high in environmental protection value, the polyethylene wax modification method comprises the following steps: performing oxidation modification treatment on polyethylene wax by comparing different oxidizing gases, and carbon dioxide better controls the oxidation degree due to weaker oxidability; the oxidation effects at different reaction temperatures are compared, and the optimal reaction time is determined; the polyethylene wax needs to be excited at a high temperature, the polyethylene wax is used as a raw material, the used raw material can be completely melted at 105-120 DEG C, and conditions need to be optimized in the process to find a proper reaction temperature; the modified polyethylene wax product with high acid value and excellent color is obtained through modification. Carbon dioxide is selected in the oxidation process, the double-carbon policy is met, the production cost is effectively reduced, and a new thought is provided for environment-friendly production of polyethylene wax while the product quality is kept; the modified polyethylene wax has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry, and in particular relates to a method for preparing oxidatively modified polyethylene wax by using carbon dioxide. Background Art

[0002] Polyethylene wax is non-toxic, non-corrosive, and has good wear resistance. The modified polyethylene wax has high added value and can be used in various masterbatch dispersants, polyolefin release agents, processing lubricants, etc. It is widely used in general plastic processing. However, most oxidative modifications use catalysts, which increases production costs when separating catalysts from products. At present, the preparation of oxidized polyethylene wax in university chemistry laboratories relies on high-pressure reactors, which makes the gas and polyethylene wax insufficiently contacted and the temperature in the reactor difficult to control.

[0003] The patent with publication number CN107286274A provides a preparation device and method of high-density oxidized polyethylene wax. The invention adds polyethylene resin to a cracking device for cracking to obtain polyethylene wax water, then the polyethylene wax water enters a collection tank to remove oligomers and is cooled down, and the cooled polyethylene wax water is discharged into an oxidation reactor for oxidation. In this process, by-products are easily generated, which affect the reaction results, resulting in uneven oxidation products, with highly oxidized parts and very slightly oxidized wax molecules.

[0004] The patent with publication number CN116874965A provides a nano-modified polyethylene wax and a preparation method thereof. The chemically modified polyethylene wax described in the patent adopts nano-SiO 2 or nano-TiO 2 The modified polyethylene wax is nano-modified to obtain nano-modified polyethylene wax. Before this process occurs, the polyethylene wax needs to be purified, which increases the production cost.

[0005] Liang Xin et al. used air as an oxidant in their study on the oxidation modification of polyethylene wax. They proposed that PEW and solvent should be uniformly mixed at a certain ratio and then added to a high-pressure reactor. After purging with air for 10 minutes, the stirring device should be turned on, and air should be introduced at a set rate. The temperature should be heated to the excitation temperature, kept for a period of time, and then quickly reduced to the reaction temperature. After a certain period of constant temperature reaction, the heating should be stopped. In this process, a temperature gradient will be generated in the reactor and on the reactor wall, which will affect the product. The article does not mention what solvent is used.

[0006] Therefore, it is necessary to invent a method for controlling production costs and maximizing the contact area between the reaction gas and the polyethylene wax phase to solve the above problems. Summary of the invention

[0007] In order to solve the defects and shortcomings in the above-mentioned prior art, the present invention provides a method for preparing oxidatively modified polyethylene wax using carbon dioxide, which can reduce production costs, maximize the contact area between the reaction gas and the polyethylene wax, and obtain high-value-added modified polyethylene wax.

[0008] To achieve the above object, the present invention adopts the following technical scheme: a method for preparing oxidatively modified polyethylene wax using carbon dioxide, Use different oxidizing gases: carbon dioxide and air to oxidize and modify polyethylene wax. Weigh a certain amount of polyethylene wax raw material and place it in a porcelain boat of corresponding volume. After carbon dioxide is introduced, check the air tightness of the pipeline. After bubbles emerge evenly in the exhaust gas treatment device, set the reaction time, reaction temperature and reaction pressure through the device for preparing oxidized modified polyethylene wax and start the device. Under the same conditions, find out the optimal reaction time, reaction temperature and contact area when carbon dioxide is used as an oxidant. Weigh a certain amount of polyethylene wax raw material and place it in a porcelain boat with the above-mentioned optimal contact area. Set the reaction time and reaction temperature through the device for preparing oxidized modified polyethylene wax and start the device. Compare the comprehensive evaluation such as the degree of oxidation under these conditions.

[0009] Preferably, the device for preparing oxidatively modified polyethylene wax comprises a tubular furnace reactor connected to a gas collecting tank, and the porcelain boat is placed in the tubular furnace.

[0010] Preferably, the polyethylene wax raw material is evenly spread on the bottom of porcelain boats of different sizes to increase the contact area of ​​the two-phase interface.

[0011] Preferably, 10 g of polyethylene wax raw material is weighed; the reaction temperatures are set to 180° C., 190° C., and 200° C. respectively; and the reaction times are set to 6 h, 8 h, 10 h, and 12 h respectively.

[0012] Preferably, the tubular furnace reactor adopts a quartz tube with an outer diameter of 40 mm, an inner diameter of 34 mm and a length of 1000 mm.

[0013] Preferably, the tubular furnace reactor requires two different types of porcelain boats: 120mm*60mm*40mm and 90mm*20mm*10mm during the experiment.

[0014] Preferably, the pressure when carbon dioxide is introduced into the tubular furnace reactor is set to 0.2 MPa.

[0015] Preferably, the air tightness of the tubular furnace reactor needs to be tested before the device is put into operation.

[0016] Preferably, after the modified polyethylene wax is fired under different reaction conditions, the modified polyethylene wax is evaluated by acid value and appearance color; the acid value determination method refers to NB / SH / T0809-2010.

[0017] Compared with the prior art, the beneficial effect of the present invention is to use different oxidizing gases to oxidize and modify polyethylene wax, find out the optimal reaction time and reaction temperature when carbon dioxide is used as an oxidant under the same conditions, and find that the acid value is not much different from that after oxidation with air under this condition, and the acid value of the modified polyethylene wax is high and the color is excellent. Carbon dioxide is selected in the oxidation process, which not only complies with the "dual carbon" policy, but also effectively reduces production costs; while maintaining product quality, it also provides a new idea for the environmentally friendly production of polyethylene wax; the modified polyethylene wax has a wide range of application prospects and broadens the application field of polyethylene wax. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 Schematic diagram of samples of oxidized polyethylene wax (OPEW) prepared at various temperatures in the present invention. DETAILED DESCRIPTION

[0019] The present invention will be described clearly and completely below in conjunction with the technical solutions in the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] like Figure 1 As shown, the present invention discloses a process for oxidatively modifying polyethylene wax with high environmental value, which can reduce production costs. The modified polyethylene wax includes using different oxidizing gases: carbon dioxide and air to oxidatively modify polyethylene wax respectively. The device for preparing oxidatively modified polyethylene wax includes a tubular furnace. 10g of polyethylene wax raw material is weighed and placed in porcelain boats of different sizes respectively. The polyethylene wax is modified by carbon dioxide because carbon dioxide has weak oxidizing properties. The reaction temperature is set at 180°C, 190°C, and 200°C; the reaction time is set at 6h, 8h, 10h, and 12h. The two different types of porcelain boats are 120mm*60mm*40mm and 90mm*20mm*10mm, so as to compare the contact area between the reaction gas and the polyethylene wax. When carbon dioxide is introduced into the tubular furnace, the pressure is set to 0.2MPa. The tubular furnace reactor (quartz tube) has an outer diameter of 40mm, an inner diameter of 34mm, and a length of 1000mm; so that porcelain boats of two sizes can be placed in the tube. Example

[0021] Place 10g of polyethylene wax raw material in a 120mm*60mm*40mm porcelain boat. The polyethylene wax can be evenly spread on the bottom of the porcelain boat, increasing the contact area of ​​the two-phase interface. After the carbon dioxide is introduced, check the air tightness of the pipeline. After bubbles are evenly emitted from the tail gas treatment device, set the program. The preferred reaction time is 6h, and the sample acid value at a reaction temperature of 190°C is 7.1259KOH / g, and the product color is the best. The acid value of unmodified polyethylene wax is 3.9110KOH / g. Example

[0022] Place 10g of polyethylene wax raw material in a 90mm*20mm*10mm porcelain boat. After introducing carbon dioxide, check the air tightness of the pipeline. After bubbles are uniformly emitted from the tail gas treatment device, set the program. The preferred reaction time is 10h, and the sample acid value at a reaction temperature of 190℃ is 7.7287KOH / g, and the product color is the best. The acid value of unmodified polyethylene wax is 3.9110KOH / g. Example

[0023] Place 10g of polyethylene wax raw material in a 90mm*20mm*10mm porcelain boat, use air as the oxidizing gas, and set the program. The preferred reaction time is 6h, and the sample acid value at a reaction temperature of 180°C is 8.3513KOH / g, and the product color is the best. The acid value of unmodified polyethylene wax is 3.9110KOH / g.

[0024] like Figure 2 As shown in the figure, the color of the sample of polyethylene wax (PEW) burned at 190°C is the best. After increasing the oxidation area, the product shows obvious carbonization at 200°C. In addition, obvious white patches appear on the edges of some samples.

[0025] The acid value in the present invention refers to the number of milligrams of KOH required to neutralize 1g of sample, and is an important parameter for identifying the degree of oxidation of polyethylene wax. Refer to NB / SH / T0809-2010.

[0026] When the present invention uses carbon dioxide to perform oxidation modification treatment on polyethylene wax, a comparison table of the acid values ​​of the products obtained at different temperatures, times and porcelain boat sizes is shown in Table 1.

[0027]

[0028] Table 1 The invention discloses a process method for oxidatively modifying polyethylene wax with high environmental value, which can reduce production costs. The modified polyethylene wax method includes comparing different oxidizing gases to perform oxidative modification treatment on polyethylene wax. Carbon dioxide has weaker oxidizing property, so the degree of oxidation can be better controlled. The oxidation effects at different reaction temperatures (180°C, 190°C and 200°C) are compared to determine the optimal reaction time. The polyethylene wax needs high-temperature excitation. The polyethylene wax is used as a raw material. The raw material used can be completely melted at 105-120°C. This process requires optimizing conditions to find a suitable reaction temperature. After modification, a modified polyethylene wax product with high acid value and excellent color is obtained. The invention uses carbon dioxide in the oxidation process, which not only complies with the "dual carbon" policy, but also effectively reduces production costs; while maintaining product quality, it also provides a new idea for the environmentally friendly production of polyethylene wax; the modified polyethylene wax has a wide range of application prospects, and can be applied to masterbatches, polyethylene wax emulsions, ink coatings, etc., thereby broadening the application field of polyethylene wax.

[0029] The present invention uses different oxidizing gases to oxidize and modify polyethylene wax, and finds the optimal reaction time, reaction temperature, etc. when carbon dioxide is used as an oxidant under the same conditions. The modified polyethylene wax obtained under the conditions has a high acid value and excellent color. Similarly, under the reaction time and temperature set in the present invention, the color and acid value of the product of polyethylene wax modified by carbon dioxide at 190°C and air are not much different.

[0030] Although specific embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the specific embodiments without departing from the principles and spirit thereof, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing oxidatively modified polyethylene wax using carbon dioxide, characterized in that: Use different oxidizing gases: carbon dioxide and air to oxidize and modify polyethylene wax. Weigh a certain amount of polyethylene wax raw material and place it in a porcelain boat of corresponding volume. After passing carbon dioxide, check the air tightness of the pipeline. After bubbles emerge evenly in the tail gas treatment device, set the reaction time, reaction temperature and reaction pressure through the device for preparing oxidized polyethylene wax and start the device. Under the same conditions, find the optimal reaction time, reaction temperature and contact area when carbon dioxide is used as the oxidant, and change the oxidant to air for firing.

2. The method for preparing oxidatively modified polyethylene wax using carbon dioxide according to claim 1, characterized in that: The device for preparing oxidatively modified polyethylene wax comprises a tubular furnace reactor connected to a gas collecting tank, and the porcelain boat is installed in the tubular furnace.

3. The method for preparing oxidatively modified polyethylene wax using carbon dioxide according to claim 1, characterized in that: The polyethylene wax raw material is evenly spread on the bottom of porcelain boats of different sizes, increasing the contact area of ​​the two-phase interface.

4. The method for preparing oxidatively modified polyethylene wax using carbon dioxide according to claim 1, characterized in that: Weigh 10 g of polyethylene wax raw material; set the reaction temperatures to 180° C., 190° C., and 200° C. respectively; and set the reaction times to 6 h, 8 h, 10 h, and 12 h respectively.

5. The method for preparing oxidatively modified polyethylene wax using carbon dioxide according to claim 1, characterized in that: The tubular furnace reactor adopts a quartz tube with an outer diameter of 40 mm, an inner diameter of 34 mm and a length of 1000 mm.

6. The method for preparing oxidatively modified polyethylene wax using carbon dioxide according to claim 1, characterized in that: The tubular furnace reactor requires two different types of porcelain boats during the experiment, 120mm*60mm*40mm and 90mm*20mm*10mm.

7. The method for preparing oxidatively modified polyethylene wax using carbon dioxide according to claim 1, characterized in that: When carbon dioxide is introduced into the tubular furnace reactor, the pressure is set to 0.2 MPa.

8. The method for preparing oxidatively modified polyethylene wax using carbon dioxide according to claim 1, characterized in that: The air tightness of the tubular furnace reactor needs to be tested before the device is put into operation.

9. The method for preparing oxidatively modified polyethylene wax using carbon dioxide according to claim 1, characterized in that: After the modified polyethylene wax is fired under different reaction conditions, the modified polyethylene wax is evaluated by acid value and appearance color. The acid value determination method refers to NB / SH / T0809-2010.

Images