阅读说明：本技术 一种高密度氧化聚乙烯蜡的制备方法及系统 (Preparation method and system of high-density oxidized polyethylene wax ) 是由 齐锋国 孙强 齐峰全 于 2021-01-25 设计创作，主要内容包括：一种高密度氧化聚乙烯蜡的制备方法及系统,属于氧化聚乙烯蜡制备技术领域。在水性涂料中需要使用高密度氧化聚乙烯蜡。现有水性涂料使用的高密度氧化聚乙烯蜡,部分工艺是将高密度聚乙烯蜡分散到水中后氧化获得,生产过程中会产出大量废水无法有效处理；直接氧化熔融态的高密度聚乙烯,因粘度大,氧气无法有效分散,产品交联和黄变严重,皂化值偏高；使高密度聚乙烯树脂经碾磨粉碎后氧化,因原料被致密化,生产周期过长,产品附加值下降,且氧化均匀度大幅下降。本发明先热裂解一步,后利用高压柱塞泵将高密度聚乙烯蜡喷射为粉末状,在空气中分散,然后再氧化,有效提高高密度氧化聚乙烯蜡的性能与生产效率。并且不需要用水,更环保、安全。(A preparation method and a system of high-density oxidized polyethylene wax belong to the technical field of oxidized polyethylene wax preparation. The use of high density oxidized polyethylene waxes in aqueous coatings is desirable. Part of processes of high-density oxidized polyethylene wax used in the existing water-based paint are obtained by dispersing the high-density polyethylene wax in water and then oxidizing, and a large amount of waste water generated in the production process cannot be effectively treated; the high-density polyethylene in a molten state is directly oxidized, and due to the large viscosity, oxygen cannot be effectively dispersed, the product is seriously crosslinked and yellowed, and the saponification value is higher; the high-density polyethylene resin is oxidized after being milled and crushed, and the production period is overlong, the added value of the product is reduced and the oxidation uniformity is greatly reduced because the raw material is densified. The invention firstly carries out thermal cracking in one step, then utilizes the high-pressure plunger pump to spray the high-density polyethylene wax into powder, disperses the powder in the air, and then oxidizes the powder, thereby effectively improving the performance and the production efficiency of the high-density oxidized polyethylene wax. And does not need water, and is more environment-friendly and safer.)

1. A preparation method of high-density oxidized polyethylene wax is characterized by comprising the following steps: the method comprises the following steps:

1) thermally cracking the high-density polyethylene resin at 180-500 ℃ to obtain molten high-density polyethylene wax;

2) spraying the molten high-density polyethylene wax into powder by high-pressure spraying;

3) adding the powder obtained in the step 2) into a degradation kettle (4), adding a catalyst, heating to 90-120 ℃, introducing air, and discharging when the acid value is detected to be 27-33 to obtain the high-density oxidized polyethylene wax.

2. The method for preparing a high-density oxidized polyethylene wax according to claim 1, wherein: the viscosity of the molten high-density polyethylene wax in the step 1) at 200 ℃ is 9000-11000 cp.

3. The method for preparing a high-density oxidized polyethylene wax according to claim 1, wherein: step 1) thermally cracking the high-density polyethylene resin by using a high-temperature extruder.

4. The method for preparing a high-density oxidized polyethylene wax according to claim 1, wherein: and 2) outputting the high-pressure spray at 10-20 MPa.

5. The method for preparing a high-density oxidized polyethylene wax according to claim 1, wherein: and 2) spraying the powder obtained in the step 2) into powder, and sieving the powder by a sieving machine to obtain powder with the particle sizes of 70-150 microns, 150-250 microns and 250-380 microns respectively.

6. The method for preparing a high-density oxidized polyethylene wax according to claim 5, wherein: heating the powder with the particle size of 70-150 mu m in the step 3) in a degradation kettle (4) to 90-120 ℃, and introducing air for 9-15 h; heating the powder with the particle size of 150-250 microns in the step 3) in a degradation kettle (4) to 90-120 ℃, and introducing air for 13-21 h; heating the powder with the particle size of 250-380 mu m in the step 3) in a degradation kettle (4) to 90-120 ℃, and introducing air for 18-25 h.

7. The method for preparing a high-density oxidized polyethylene wax according to claim 1, wherein: the degradation kettle (4) in the step 3) comprises a kettle body and a jacket, wherein a heat-conducting medium is arranged in the jacket, and an airflow classifier is arranged in the kettle body.

8. A system for use in the method for preparing a high-density oxidized polyethylene wax according to any one of claims 1 to 7, wherein: the method comprises the following steps: the device comprises an extruder (1), a storage tank (5), a high-pressure spray tower (2), a rotary vibration sieve (3) and a degradation kettle (4); the outlet of the extruder (1) is connected with a storage tank (5), the outlet of the storage tank (5) is connected with the inlet of a high-pressure spray tower (2), the outlet of the high-pressure spray tower (2) is connected with a rotary vibration sieve (3), and the discharge hole of the rotary vibration sieve (3) is connected with the feed inlet of a degradation kettle (4); and a high-pressure plunger pump is arranged in the high-pressure spray tower (2).

9. The system of claim 8, wherein: the air supply system comprises an air supply system (6), an air outlet of the air supply system (6) is connected with a discharge hole of the rotary vibration sieve (3), the air supply system (6) comprises an electric heater (7), a condenser (8) and a Roots blower (9), the electric heater (7) is connected with the condenser (8) in parallel and then arranged at the Roots blower (9) and an air outlet, and switches are arranged on parallel pipelines of the electric heater (7) and the condenser (8).

Technical Field

A preparation method and a system of high-density oxidized polyethylene wax belong to the technical field of oxidized polyethylene wax preparation.

Background

The oxidized polyethylene wax, also called OPE wax, has the special properties of low viscosity, high softening point, good hardness and the like, no toxicity, good thermal stability, low high-temperature volatility, excellent dispersibility for fillers and pigments, excellent external lubricity, strong internal lubrication effect and coupling effect. The higher the density and the higher the melting point of the oxidized polyethylene wax emulsion, the harder the film, the finer the particle size, the better the quality, the finer the texture and the better the effect. The use of high density oxidized polyethylene waxes in aqueous coatings is desirable.

Part of processes of high-density oxidized polyethylene wax used in the existing water-based paint are obtained by dispersing the high-density polyethylene wax in water and then oxidizing, and a large amount of waste water generated in the production process cannot be effectively treated; the high-density polyethylene in a molten state is directly oxidized, and due to the fact that the viscosity is high, oxygen cannot be effectively dispersed, cross-linking and yellowing of a product are serious, and oxidized wax with a high acid value cannot be obtained; the high-density polyethylene wax is oxidized by using an autoclave at a high temperature, so that the risk is high and the safety coefficient is low; the high-density polyethylene resin is oxidized after being milled and crushed, because the raw materials are densified, the production period is too long, the added value of the product is reduced, the oxidation uniformity is greatly reduced, the unoxidized raw materials cannot be thoroughly emulsified when being used as a water-based coating, so that the stability of the coating product is greatly influenced, the melt index of the raw materials of the high-density polyethylene resin is uncontrollable, the product quality is unstable, and the acid value and the viscosity fluctuation are large.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: overcomes the defects of the prior art, and provides a preparation method and a system of high-density oxidized polyethylene wax with little pollution, few byproducts, mild overall process and uniform oxidation.

The technical scheme adopted by the invention for solving the technical problems is as follows: a preparation method of high-density oxidized polyethylene wax is characterized by comprising the following steps: the method comprises the following steps:

1) thermally cracking the high-density polyethylene resin at 180-500 ℃ to obtain molten high-density polyethylene wax;

2) spraying the molten high-density polyethylene wax into powder by high-pressure spraying;

3) adding the powder obtained in the step 2) into a degradation kettle, adding a catalyst, heating to 90-120 ℃, introducing air, and discharging when the acid value is 27-33 through detection to obtain the high-density oxidized polyethylene wax.

The high pressure spray is preferably a high pressure plunger pump.

The high-density polyethylene wax is dispersed into the air by high-pressure spraying equipment such as a high-pressure plunger pump and the like without being dispersed in water, so that no waste water is generated, the water consumption is saved, and the pollution is reduced; the high-pressure environment is needed for avoiding gasification after the high-pressure environment is dispersed in water, and the invention can be realized by using a normal-pressure kettle under normal pressure; the high-pressure plunger pump has high speed of dispersing the high-density polyethylene wax in the air, the particle size can be adjusted and controlled by the pressure of the high-pressure plunger pump, and the production process is easy to control; the dispersion efficiency is high, and the production period is shorter; the whole dispersion process avoids the powder particles from being compacted and densified due to grinding and crushing, air can enter the particles more easily in the oxidation process, the high-density polyethylene wax is oxidized more uniformly, and the product quality is more stable; the temperature of the two-step degradation is low, particularly after the oxidation in the air is realized, the temperature required by the oxidation in the step 3) is obviously reduced, and the generation amount of byproducts is reduced within the range of 90-120 ℃.

Preferably, the catalyst in step 3) is organic peroxide or azobisisobutyronitrile at a concentration of ten-thousandth of high-density polyethylene wax, wherein the organic peroxide comprises benzoyl peroxide and lauroyl peroxide. The optimized catalyst can effectively accelerate the oxidative degradation speed of the high-density polyethylene wax. Theoretically, a compound capable of generating free radicals is required as a catalyst for accelerating oxidative degradation, but benzoyl peroxide is more preferable, and benzoyl peroxide can significantly reduce the oxidative induction period and shorten the degradation time.

Preferably, the viscosity of the molten high-density polyethylene wax obtained in the step 1) at 200 ℃ is 9000-11000 cp. The viscosity of the cracked high-density polyethylene wax can be controlled by controlling the temperature or the thermal cracking time in the step 1), and the preferred viscosity range is that the high-pressure plunger pump in the step 2) can more easily spray the particle size which is beneficial to oxidation and has narrow distribution.

Preferably, step 1) thermally cracks the high density polyethylene resin using a high temperature extruder.

Preferably, the high-pressure spraying output pressure in the step 2) is 10-20 MPa. The powder sprayed in the pressure range has narrow particle size distribution, proper size and easy control.

Preferably, the powder sprayed in the step 2) is sieved by a sieving machine to obtain powder with the particle size of 70-150 microns, 150-250 microns and 250-380 microns respectively. The oversize particles can be directly returned to the melt obtained in the previous step for remelting and then spraying, and can also be directly carried out in the next step, so that the waste amount is very small. The sprayed powdery high-density polyethylene wax is distinguished and then is oxidized, so that the process conditions can be controlled more pertinently in the step 3), and the final high-density oxidized polyethylene wax has a more stable oxidation state by adopting different process conditions for the powder with different particle sizes.

Preferably, the powder with the particle size of 70-150 mu m in the step 3) is heated to 90-120 ℃ in a degradation kettle (4), and air is introduced for 9-15 hours; heating the powder with the particle size of 150-250 microns in the step 3) in a degradation kettle (4) to 90-120 ℃, and introducing air for 13-21 h; heating the powder with the particle size of 250-380 mu m in the step 3) in a degradation kettle (4) to 90-120 ℃, and introducing air for 18-25 h. The high-density oxidized polyethylene wax with the best performance can be obtained by adopting the process conditions for the high-density polyethylene wax with different particle sizes. And the reaction time corresponding to each particle diameter can be controlled to be within a desired range.

Preferably, the degradation kettle in the step 3) comprises a kettle body and a jacket, wherein a heat-conducting medium is arranged in the jacket, and an airflow classifier is arranged in the kettle body. Through the amount of wind speed of control air inlet and the swiveling wheel rotational speed of air current grader, can effectually avoid the powder in the degradation cauldron to be blown out the degradation cauldron.

A system for the preparation method of the high-density oxidized polyethylene wax is characterized in that: the method comprises the following steps: the device comprises an extruder, a storage tank, a high-pressure spray tower, a rotary vibration sieve and a degradation kettle; the outlet of the extruder is connected with a storage tank, the outlet of the storage tank is connected with the inlet of a high-pressure spray tower, the outlet of the high-pressure spray tower is connected with a rotary vibration sieve, and the discharge port of the rotary vibration sieve is connected with the feed port of the degradation kettle; and a high-pressure plunger pump is arranged in the high-pressure spray tower.

The high-density polyethylene resin is extruded and degraded into high-density polyethylene wax at high temperature by an extruder, the molten high-density polyethylene wax stays in a storage tank or directly enters a high-pressure spray tower to be sprayed into powder, then the powder is screened by a rotary vibration sieve for particle size classification, and finally the powder reaches a degradation kettle to be oxidized and degraded into the high-density oxidized polyethylene wax.

Preferably, the gas supply system is further included, a gas outlet of the gas supply system is connected with a discharge port of the rotary vibration sieve, the gas supply system comprises an electric heater, a condenser and a Roots blower, the electric heater and the condenser are connected in parallel and then arranged between the Roots blower and the gas outlet of the gas supply system, and a switch is arranged on a parallel pipeline of the electric heater and the condenser.

Air supply system uses the air to carry the high density low molecular weight polyethylene that the sieve that shakes soon to degradation cauldron in, provides the air to degradation cauldron simultaneously, and roots's fan provides whole air supply system's wind pressure to can select to heat or cool down the air through electric heater or condenser, the air cooperation that utilizes the different temperatures that air supply system blew out degrades the heat-conducting medium in the cover of pressing from both sides of cauldron, can the temperature in the efficient control degradation cauldron.

Compared with the prior art, the invention has the beneficial effects that: the whole process does not generate waste water, saves water and protects the environment; the production process is easy to control the dispersion effect of the high-density polyethylene wax and adopts different oxidation modes aiming at different dispersion effects to ensure that the product quality is stable; the powder is not ground and extruded, so that the powder is loose in structure, easy to oxidize, better in performance and shorter in production period; the process conditions are mild, the safety is high, and the byproducts are few.

Drawings

FIG. 1 is a system for preparing a high-density oxidized polyethylene wax according to example 1.

Wherein, 1 extruder, 2 high-pressure spray towers, 3 rotary vibration sieves, 4 degradation kettles, 5 storage tanks, 6 gas supply systems, 7 electric heaters, 8 condensers and 9 Roots blowers.

Detailed Description

The invention is further illustrated with reference to fig. 1, in which example 2 is the preferred embodiment of the invention. The high density polyethylene resins used in the following examples are all characterized by a melt index of 0.1 to 3.

Example 1

Referring to figure 1: a preparation system of high-density oxidized polyethylene wax comprises: the device comprises an extruder 1, a storage tank 5, a high-pressure spray tower 2, an air supply system 6, a rotary vibration sieve 3 and a degradation kettle 4; an outlet of the extruder 1 is connected with a storage tank 5, an outlet of the storage tank 5 is connected with an inlet of a high-pressure spray tower 2, an outlet of the high-pressure spray tower 2 is connected with a rotary vibration sieve 3, and a discharge hole of the rotary vibration sieve 3 is connected with a feed hole of a degradation kettle 4; a high-pressure plunger pump is arranged in the high-pressure spray tower 2; the degradation kettle 4 comprises a kettle body and a jacket, wherein a heat-conducting medium is arranged in the jacket, and an airflow classifier is arranged in the kettle body; the gas outlet of the gas supply system 6 is connected with the discharge hole of the rotary vibration sieve 3, the gas supply system 6 comprises an electric heater 7, a condenser 8 and a Roots blower 9, the electric heater 7 is connected with the condenser 8 in parallel and then arranged between the Roots blower 9 and the gas outlet of the gas supply system 6, and the parallel pipelines of the electric heater 7 and the condenser 8 are respectively provided with a switch.

The high-density polyethylene resin is extruded and degraded into high-density polyethylene wax at high temperature by an extruder 1, the molten high-density polyethylene wax enters a high-pressure spray tower 2 through a storage tank 5 and is sprayed into powder by a high-pressure plunger pump, then the powder is screened by a rotary vibration screen 3 for particle size classification, and finally the powder reaches a degradation kettle 4 for oxidation and degradation into the high-density oxidized polyethylene wax.

A preparation method of high-density oxidized polyethylene wax comprises the following steps:

1) the high-density polyethylene resin is thermally cracked by a high-temperature resistant extruder at 500 ℃ to obtain molten-state high-density polyethylene wax, and the thermal cracking temperature of the extruder 1 and the viscosity of the obtained high-density polyethylene wax are shown in Table 1 below;

TABLE 1 example 1 temperature for thermal cracking in extruder and viscosity of high density polyethylene wax obtained

。

2) The high-density polyethylene wax in the molten state obtained in the step 1) enters a high-pressure spray tower 2 through a storage tank 5, namely, the high-pressure plunger pump is sprayed into powder, and the pressure of the high-pressure plunger pump is 10 MPa; sequentially screening high-density polyethylene wax powder by a rotary vibration screen 3 according to the order of particle size from small to large, and carrying out the next step, wherein particles with the particle size of more than 380 mu m return to the storage tank for melting and re-spraying, and the particle sizes and the distribution are shown in the following table 2;

table 2 example 1 particle size and distribution

。

3) Adding the powder obtained in the step 2) into a degradation kettle 4 according to the required particle size, adding benzoyl peroxide with the concentration of one ten-thousandth of the weight of the powder, heating to 90-120 ℃, introducing air, and discharging when the acid value is detected to be 27-33 to obtain high-density oxidized polyethylene wax; the oxidative degradation conditions for each particle size are shown in table 3 below;

table 3 example 1 conditions for oxidative degradation of various particle sizes

Example 2

The preparation method of the high-density oxidized polyethylene wax is the same as that of the example 1 in other conditions, and the pressure of the high-pressure plunger pump in the step 2) is set to be 20Mpa, and the particle sizes and the distribution are shown in the following table 4;

table 4 particle size and distribution of example 2

。

The oxidative degradation conditions of the particle sizes in step 3) are shown in Table 5 below;

table 5 example 2 oxidative degradation conditions for each particle size

。

Example 3

The other conditions of the preparation method of the high-density oxidized polyethylene wax are the same as those of the example 1, and the thermal cracking temperature of the extruder 1 in the step 1) and the viscosity of the obtained high-density polyethylene wax are shown in the following table 6;

TABLE 6 example 3 temperature for thermal cracking in extruder and viscosity of high density polyethylene wax obtained

。

Step 2) the particle sizes and distributions are shown in table 7 below;

table 7 particle size and distribution of example 3

。

The oxidative degradation conditions of each particle size in step 3) are shown in table 8 below;

table 8 example 3 oxidative degradation conditions for each particle size

。

Example 4

The other steps of the preparation method of the high-density oxidized polyethylene wax are the same as those of the embodiment 1, and the step 2) directly enters a degradation kettle 4 for oxidative degradation without sieving the particle size by a rotary vibrating screen 3. Discharging when the acid value is detected to be 30 in the step 3), and taking 47 h.

Example 5

The other steps of the preparation method of the high-density oxidized polyethylene wax are the same as the example 1, and the particle sizes and the distribution of the step 2) are shown in the following table 9;

table 9 particle size and distribution of example 5

。

Step 3) oxidative degradation conditions for each particle size are shown in table 10 below;

TABLE 10 example 5 oxidative degradation conditions for each particle size

。

Comparative example 1

A preparation method of high-density oxidized polyethylene wax is disclosed, wherein the step 1) is the same as the step 1, the step 2) is to introduce the molten high-density polyethylene wax obtained in the step 1) into an oxidation kettle, water, a dispersing agent with the concentration of 10 percent and benzoyl peroxide with the concentration of 5 percent of the weight of the high-density polyethylene wax are contained in the oxidation kettle, the temperature is increased to 130 ℃, the pressure is increased to 1.7MPa, air is continuously introduced for oxidation, and when the oxidation is carried out for 50 hours, 1 ton of high-density oxidized polyethylene wax with the detected acid value of 30 is prepared.

Comparative example 2

A preparation method of high-density oxidized polyethylene wax is provided, steps 1) and 3) are the same as example 1, and step 2) is that the high-density polyethylene wax in a molten state obtained in the step 1) is cooled and solidified, and then ground into powder by a grinder.

Performance testing

And (3) viscosity detection: the viscosity was measured using a Bohler fly viscometer at 150 ℃.

And (3) melting range detection: the melting point instrument is produced by Shanghai apparatus electro-physical optical instruments Limited company for detection.

Detection of a production cycle: the ratio of the time when all the high-density polyethylene resin is consumed to the total amount of the high-density polyethylene resin used.

And (3) acid value detection: according to GB/T264-1983.

The performance test results are shown in Table 11 below;

TABLE 11 results of Performance testing

。

The high-density oxidized polyethylene wax obtained by the method has low and stable viscosity and small fluctuation range, because the high-density polyethylene wax obtained by the method adopts targeted oxidative degradation according to different particle sizes and different dispersion conditions, all the particle sizes can be fully oxidized, the problem that small particles are excessively oxidized and large particles are not oxidized is not considered, and the finished product does not have unoxidized raw materials; the finished products obtained in the embodiments 1-5 are short in melting range, stable in performance and easy to process subsequently, and the finished products with certain particle size can be used independently according to needs, so that the fluctuation ranges of the melting range, the viscosity and the like are further reduced, and the products and the performance are fine; in comparative examples 1-2, the polyethylene wax with over-dispersion (too small particle size) and under-dispersion (large particle size) needs to be considered at the same time, so that sufficient oxidation is difficult, and particularly in comparative example 2 after grinding, particles are densified, oxygen is difficult to permeate into the particles, and the oxidation effect is poor; the difference between the saponification value and the acid value is small in examples 1-5, because few byproducts are generated in the preparation process, particularly, few lipid substances are generated, the saponification value is stable, and the product quality is higher; in the embodiment 2, the production efficiency can be improved by adopting 15MPa high-pressure plunger pump injection, and meanwhile, more particles with the particle size of 75-250 microns are sprayed, so that the subsequent oxidative degradation is facilitated, and the performance of the obtained product is more stable.

The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.