A treatment apparatus and method for reducing the odor rating of polyolefin resins

Abstract

The application discloses a processing device for reducing the odor grade of polyolefin resin, which comprises a solution tank, a heating device and a steam cylinder; in use, the solution flowing out of the solution tank is heated by the heating device to form steam, and then the steam is contacted with the polyolefin resin to be processed in the steam cylinder, so that the odor substances of small molecules which are easy to volatilize in the polyolefin resin are removed, and thus the odor grade of the polyolefin resin is greatly reduced. In the device, any decompression or pressurization equipment is not needed, and thus the investment cost is greatly reduced; one or more porous sieve plates arranged in the steam cylinder can greatly increase the contact area of the polyolefin resin and the steam, so that the processing time can be greatly shortened while the odor grade is reduced, and other impurities cannot be introduced into the polyolefin resin.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high polymer materials, and particularly relates to a treatment device for reducing the odor grade of polyolefin resin. BACKGROUND

[0002] Polyolefin materials are widely used in national defense, energy, automobiles, construction, packaging, textiles, medical treatment and many other fields, and have become one of the important materials supporting social development. With the continuous improvement of people's living standards and quality of life and the continuous enhancement of health and environmental protection awareness, the odor parameters of polyolefin materials have become a key indicator for judging the quality of products such as automobile interiors, sanitary materials and food packaging materials. Therefore, it is necessary to provide a method capable of effectively reducing the odor grade of polyolefin resin. SUMMARY

[0003] In order to improve the problem of strong odor of polyolefin materials, the present application provides a treatment device and method for reducing the odor grade of polyolefin resin, which can effectively solve the difficulty that the existing polyolefin materials have relatively heavy odor and cannot enter the high-end polyolefin field.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0005] A treatment device for reducing the odor grade of polyolefin resin, comprising a solution tank, a heating device and a steam cylinder, the solution tank is used for storing solution, a stop valve is connected to the bottom of the solution tank, and the solution in the solution tank is pumped into the heating device through the stop valve;

[0006] The heating device is used for heating the solution flowing out of the solution tank and forming steam, and the formed steam flows into the steam cylinder through a pipeline;

[0007] The steam cylinder is provided with one or more porous sieve plates, the polyolefin resin to be treated is added from directly above the porous sieve plate, and the steam generated by the heating device is added from directly below the porous sieve plate, so that the volatile odor molecules in the polyolefin resin are removed through the contact between the steam and the polyolefin resin to be treated.

[0008] Further, the solution is water or a mixture of water and other volatile solvents that are miscible with water in any proportion. The volatile solvents that are miscible with water include ethanol and the like.

[0009] Further, the steam cylinder is divided into one or more layers by the porous sieve plate.

[0010] Further, the diameter of the sieve holes of the porous sieve plate should be not greater than the diameter of the polyolefin resin pellets.

[0011] Further, the porous screen plate is connected with a rotating handle outside the steam cylinder, and the treated polyolefin resin can fall to the bottom of the cylinder and flow out by rotating the handle.

[0012] The method for treating polyolefin resin by using the device to reduce the odor grade of the polyolefin resin comprises the following steps:

[0013] 1) storing the solution in the solution tank, and then opening the stop valve at the bottom of the solution tank;

[0014] 2) starting the heating device to heat the solution flowing out of the solution tank to form steam;

[0015] 3) adding the polyolefin resin to be treated from the upper section of the steam cylinder, and allowing the steam generated by the heating device to enter from the lower section of the steam cylinder to make the steam fully contact with the polyolefin resin to be treated, so as to remove the odor molecules easily volatilized from the polyolefin resin; the treated polyolefin resin falls to the bottom of the cylinder and flows out by rotating the rotating handle connected with the porous screen plate; and the excess steam collected above the steam cylinder is recycled to the solution tank.

[0016] Further, the solution is water or a mixture of water and other easily volatile solvents miscible with water in any proportion. The easily volatile solvents miscible with water are, for example, ethanol and the like.

[0017] Still further, the solution can further comprise cocamidopropyl betaine. Preferably, the amount of the cocamidopropyl betaine added is 0.1wt%-0.25%.

[0018] Further, the mass ratio of the solution to the polyolefin resin to be treated is 5-20:1.

[0019] Further, the polyolefin resin to be treated added into the steam cylinder each time can be flatly laid on the porous screen plate.

[0020] The treatment method can be applied to bottle cap materials, high-grade dinner boxes, automobile materials and fiber materials, and the like, which have relatively high requirements on the odor grade of the polyolefin resin, and the method avoids long-time gas purging of the polyolefin resin after odor removal, and greatly improves the production efficiency.

[0021] The advantages of the present application are as follows:

[0022] (1) The present application provides a device with less investment and convenient operation, which uses steam to take away small molecular substances easily volatilized to generate odor in the polyolefin, greatly reduces the odor grade of the polyolefin, and does not introduce other impurities into the polyolefin resin.

[0023] (2) The device does not need any decompression or pressurization equipment, which greatly reduces the investment cost.

[0024] (3) The application sets one or several porous screens in the steam cylinder, greatly increases the contact area of polyolefin resin and steam, and can greatly shorten the production time under the condition of reducing to the same odor level.

[0025] (4) The application can use a mixed solution of ethanol and water as the solution to provide steam, which not only reduces the boiling point, but also ethanol is extremely volatile, which can take away the moisture in the resin, reducing the energy consumption of drying the resin.

[0026] (5) The device can reduce the odor level of polyolefin particles at 80℃ to below 2.5 level (using VDA270:2022 standard) within 45 minutes, which is obviously effective in saving time cost.

[0027] (6) The application can also add cocamide propyl betaine to the solution, which is a pure natural zwitterionic surfactant, which can form very rich micro-bubbles by using its hydrophilic and hydrophobic effect, further increasing the contact area of steam and polyethylene resin particles, thereby quickly removing the volatile odor molecules in the polyolefin resin. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a schematic diagram of a processing device for reducing the odor level of polyolefin.

[0029] Figure 2 is a front view of a porous screen used in the steam cylinder of the processing device for reducing the odor level of polyolefin. DETAILED DESCRIPTION

[0030] A processing device for reducing the odor level of polyolefin resin, such as Figure 1 , comprising a solution tank, a heating device and a steam cylinder, the bottom of the solution tank is connected with a stop valve and a liquid flowmeter; the steam cylinder is provided with one or several porous screens. In use, the solution is stored in the solution tank, then the stop valve and the liquid flowmeter at the bottom of the solution tank are opened; the heating device is turned on to heat the solution flowing out of the solution tank to form steam; the polyolefin resin to be treated is added from the hopper at the upper segment of the steam cylinder, and the steam generated by the heating device is added from the lower segment of the steam cylinder through the gas flowmeter, so that the steam and the polyolefin resin to be treated are in full contact, thereby removing the volatile odor molecules in the polyolefin resin.

[0031] , the solution is water or a mixture of water and other volatile solvents that can be mixed with water in any proportion. The volatile solvent that can be mixed with water is ethanol and the like. Cocamide propyl betaine can also be added to the solution.

[0032] The mass ratio of the solution used to the polyolefin resin to be treated is 5-20:1.

[0033] The steam cylinder is divided into one or more layers by a porous screen plate.

[0034] The polyolefin resin to be treated added each time into the steam cylinder should be able to lay flat on the porous screen plate.

[0035] The screen hole diameter of the porous screen plate should not be larger than the pellet diameter of the polyolefin resin, and a rotating handle is connected outside the steam cylinder, and by rotating the handle, the porous screen plate can be rotated to any angle, so that the treated polyolefin resin can fall to the bottom of the cylinder and flow out.

[0036] In order to make the content of the present application more convenient to understand, the technical solutions of the present application will be further described below in combination with specific embodiments, but the present application is not limited thereto.

[0037] Example 1

[0038] 1) Add 1000 ml of solution into the solution tank.

[0039] 2) Add 150 g of bottle cap material polyolefin resin pellets into the steam cylinder, so that they lay flat on the porous screen plate.

[0040] 3) Open the stop valve at the bottom of the solution tank, adjust the flow meter to control the flow rate at 2 ml / min-20 ml / min, and open the heating device to maintain the temperature at 80-103℃ (to reach the boiling point of the solution), and then the solution in the solution tank is sent into the heating device through the stop valve and heated into steam, which is then sent into the steam cylinder; the excess steam collected from the top of the steam cylinder is recycled into the solution tank.

[0041] 4) After 45 min of steam injection, rotate the rotating handle connected to the porous screen plate to make the polyolefin resin pellets fall and flow out from the bottom of the cylinder.

[0042] According to the above steps, the removal of odor of bottle cap material polyethylene resin pellets by steam of different proportions of water and ethanol was investigated, and the odor grade was evaluated according to the VDA270:2022 standard, and compared with hot air treatment and water boiling treatment, and the results are shown in Table 1. The specific treatment conditions are as follows:

[0043] Steam treatment: the bottle cap material polyethylene resin pellets were treated by steam using pure water, 20% ethanol solution, 40% ethanol solution, 60% ethanol solution and 80% ethanol solution as the solution for 45 min.

[0044] Hot air treatment: the bottle cap material polyethylene resin pellets were dried in a blowing drying oven at 50℃, 60℃, 70℃, 80℃, 90℃, 100℃ and 110℃ for 6 h.

[0045] Water boiling treatment: bottle cap material polyethylene resin pellets were treated at 70℃, 80℃, 90℃, 100℃ water boiling conditions for 6h respectively.

[0046] Table 1 Comparison of odor grade results of samples obtained by different treatments

[0047]

[0048] As can be seen from the results in Table 1, the use of 20% ethanol solution as the solution for steam treatment has the same effect on reducing the odor grade of the sample as the use of pure water, and the addition of ethanol can reduce the boiling point and reduce the heating energy consumption, and ethanol is extremely volatile, which can also help to reduce the energy consumption when drying the resin. In contrast, with the increase of the treatment temperature, the odor grade is reduced by using hot air treatment and water boiling treatment, but when the temperature is increased to 80℃, the odor grade no longer changes or changes very little. Therefore, compared with the traditional method for reducing the odor of polyethylene resin, the method of the present application can significantly reduce the odor grade of polyethylene resin, and only 45min is needed, which greatly shortens the treatment time.

[0049] Example 2

[0050] 1) Prepare a 0.1%, 0.15%, 0.2%, 0.25% aqueous solution of cocamide propyl betaine (the purity of the cocamide propyl betaine used is 35wt%), and then mix it with ethanol at a volume ratio of 8:2 to form a mixed solution;

[0051] 2) Add 1000ml of the mixed solution to the solution tank;

[0052] 3) Add 150g of bottle cap material polyethylene resin pellets to the steam cylinder and spread them evenly on the perforated sieve plate.

[0053] 4) Open the stop valve at the bottom of the solution tank, adjust the flowmeter to control the flow rate at 2ml / min-20ml / min, and turn on the heating device to maintain the temperature at 87-90℃ (the boiling point of the solution), then pass the mixed solution in the solution tank into the heating device through the stop valve and heat it into steam, and then send it into the steam cylinder; the excess steam collected from the top of the steam cylinder is recycled into the solution tank.

[0054] 5) After 45min of steam injection, rotate the rotating handle connected to the perforated sieve plate to make the polyethylene resin pellets fall off and flow out from the bottom of the cylinder.

[0055] The removal of the odor of the polyethylene resin pellets of the bottle cap material by the mixed solution of different concentrations of the aqueous solution of cocamide propyl betaine and ethanol was investigated by the above method, and the odor grade thereof was evaluated according to the VDA270:2022 standard, and the results are shown in Table 2.

[0056] Table 2 Odor grade of samples treated by mixed solutions of different concentrations of cocamide propyl betaine

[0057]

[0058] As can be seen from the results in Table 2, the use of cocamide propyl betaine helps to remove the odor of the polyethylene resin pellets of the bottle cap material. This may be due to the fact that cocamide propyl betaine is a pure natural zwitterionic surfactant, which can form very rich microbubbles by utilizing its hydrophilic and hydrophobic effect, thereby increasing the contact area between the steam and the polyethylene resin pellets. At the same time, these rich microbubbles can extract volatile organic compounds in the melt, which helps to carry away the volatile organic small molecules by steam, thereby reducing the odor grade of the resin. Among them, when the concentration of the aqueous solution of cocamide propyl betaine is 0.15%, the polyethylene resin of the bottle cap material has no obvious odor, and further increasing the concentration of cocamide propyl betaine cannot further reduce the odor grade.

[0059] The above only describes the preferred embodiments of the present application, and any changes and modifications made within the scope of the patent application of the present application shall be included in the scope of the present application.

Claims

1. A treatment apparatus for reducing the odor grade of a polyolefin resin, comprising a solution tank, a heating device, and a steam cylinder, characterized by, The solution tank is used for storing the solution, and a stop valve is connected to the bottom of the solution tank. The solution in the solution tank is pumped into the heating device through the stop valve; The heating device is used for heating the solution flowing out of the solution tank and forming steam, and the formed steam flows into the steam cylinder through the pipeline; The steam cylinder is provided with one or more porous screens. The polyolefin resin to be treated is added from above the porous screen, and the steam generated by the heating device enters from below the porous screen, so that the steam contacts the polyolefin resin to be treated. The solution is water or a mixture of water and other volatile solvents miscible with water in any proportion. The volatile solvent miscible with water is ethanol. The solution further contains cocamide propyl betaine.

2. The treatment device for reducing odor rank of polyolefin resin according to claim 1, characterized by, The steam cylinder is divided into one or more layers by the porous screens.

3. The treatment device for reducing odor rank of polyolefin resin according to claim 1, characterized by, The diameter of the screen holes of the porous screens should not be larger than the diameter of the polyolefin resin particles.

4. The treatment device for reducing odor rank of polyolefin resin according to claim 1, characterized by, The porous screens are connected to a rotating handle outside the steam cylinder.

5. A process for reducing the odor level of a polyolefin resin using the treatment device for reducing the odor level of a polyolefin resin according to claim 1, characterized by, The method comprises the following steps: 1) Store the solution in the solution tank, and then open the stop valve at the bottom of the solution tank; 2) Start the heating device to heat the solution flowing out of the solution tank to form steam; 3) Add the polyolefin resin to be treated from the upper section of the steam cylinder, and the steam generated by the heating device enters from the lower section of the steam cylinder, so that the steam fully contacts the polyolefin resin to be treated, thereby removing the volatile odor molecules in the polyolefin resin.

6. The method of treating polyolefin resin to reduce odor rating according to claim 5, characterized in that, The mass ratio of the solution to the polyolefin resin to be treated is 5-20:

1.

7. The method of treating polyolefin resin to reduce odor grade according to claim 5, characterized by, The polyolefin resin to be treated added into the steam cylinder each time should be able to be laid on the porous screens.

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