CN114829411A

CN114829411A - Process for preparing chlorinated polyvinyl chlorides

Info

Publication number: CN114829411A
Application number: CN202080085457.0A
Authority: CN
Inventors: 洪起元; 南宫智恩; 李祐荣; 陈善正; 李昭静
Original assignee: Han Huasiluxin Zhu
Current assignee: Han Huasiluxin Zhu
Priority date: 2019-12-31
Filing date: 2020-07-13
Publication date: 2022-07-29
Also published as: WO2021137374A1; KR20210086152A

Abstract

The invention relates to a method for preparing chlorinated polyvinyl chloride, which improves the preparation efficiency of the chlorinated polyvinyl chloride and also improves the performance of the prepared chlorinated polyvinyl chloride by using a UV LED as a light source and controlling a radiation angle.

Description

Process for preparing chlorinated polyvinyl chlorides

Technical Field

The invention relates to a method for preparing chlorinated polyvinyl chloride by using a UV LED.

Background

Chlorinated polyvinyl chloride is used in various fields such as pipes, films, sheets and the like because of its excellent heat resistance. Chlorinated polyvinyl chloride is prepared by reacting polyvinyl chloride with chlorine, but in general, chlorine radicals need to be generated so that chlorine can react with polyvinyl chloride, and for this purpose, ultraviolet radiation is required.

Currently, the most common method for ultraviolet radiation in the preparation of chlorinated polyvinyl chloride is to use mercury ultraviolet lamps. Mercury uv lamps are widely used because of their low cost and ready availability, but they require frequent replacement due to their low energy efficiency and short life. In addition, since the ultraviolet rays are radially emitted from the mercury ultraviolet lamp, the ultraviolet rays may not sufficiently reach the reactant, thereby reducing the reaction efficiency.

Thus, as a result of diligent efforts to solve the problems, the inventors confirmed that the efficiency of preparing chlorinated polyvinyl chloride can be improved and the properties of the prepared chlorinated polyvinyl chloride can be improved at the same time by using a UV LED as a light source and controlling the radiation angle, and completed the present invention

Disclosure of Invention

Technical problem

The invention aims to provide a preparation method of chlorinated polyvinyl chloride, which improves the preparation efficiency of the chlorinated polyvinyl chloride and also improves the performance of the prepared chlorinated polyvinyl chloride by using a UV LED as a light source and controlling a radiation angle.

Technical scheme

In order to achieve the above object, there is provided a method for preparing chlorinated polyvinyl chloride, comprising the steps of:

1) introducing reactants comprising polyvinyl chloride and chlorine into a reactor;

2) and irradiating UV to the reactant while stirring, wherein the UV irradiation uses a UV LED disposed in the reactor as a light source, and the radiation angle of the light source is 45-110 deg.

Chlorinated polyvinyl chlorides can be prepared by reacting polyvinyl chloride with chlorine. Chlorinated polyvinyl chloride has further improved heat resistance compared to polyvinyl chloride, and thus is used in various fields such as pipes, films, sheets, and the like. In order to produce such chlorinated polyvinyl chloride, chlorine radicals need to be generated, and for this reason, ultraviolet irradiation is necessary.

Previously, mercury uv lamps were used as the source of uv radiation, but they were energy inefficient and short lived, and therefore required frequent replacement. Therefore, in the present disclosure, a UV LED is used as a light source, but during the preparation of chlorinated polyvinyl chloride, double bonds or CCl may be generated due to high light energy of the UV LED ₂ The key and thus the fear of deterioration of product performance, and thus the light source radiation angle is controlled as described above.

Step 1 is a step of introducing reactants including polyvinyl chloride and chlorine into a reactor and preparing the reaction of step 2 described later.

The reactor is not particularly limited as long as it can be used for preparing chlorinated polyvinyl chloride. Further, the reactor may be provided with means capable of controlling the conditions required in the reaction of the reactants, such as temperature control means, pressure control means, and the like. Further, since polyvinyl chloride and chlorine generally react while being stirred, a stirrer may be provided inside the reactor.

Preferably, among the reactants, polyvinyl chloride is introduced into the reactor in the form of an aqueous suspension, and therefore, preferably, the stirrer is disposed at a lower position inside the reactor. The aqueous polyvinyl chloride suspension can be prepared by mixing polyvinyl chloride with water and suspending the mixture, and the concentration of the polyvinyl chloride in the suspension can be controlled to be 1-90 wt%. Further, the suspension may be prepared first and then introduced into the reactor, or the polyvinyl chloride and water may be introduced into the reactor sequentially or simultaneously and then stirred to prepare the suspension.

Further, among the reactants, chlorine may be introduced into the reactor in a gas phase or a liquid phase. Meanwhile, since chlorine is consumed by the chlorination reaction described below, chlorine may be additionally supplied to the reactor during the chlorination reaction, and the process may be controlled by monitoring the degree of chlorination of polyvinyl chloride.

Further, the introduced amount of the reactant may be appropriately controlled in consideration of the size of the reactor, and the like.

Step 2 is a step of stirring the reactants introduced into the reactor while irradiating with ultraviolet rays to perform a chlorination reaction.

The temperature of the chlorination reaction is preferably 55-95 ℃. If the temperature of the chlorination reaction is lower than 55 ℃, the chlorination reaction may not be sufficiently performed, and if the temperature of the chlorination reaction is higher than 95 ℃, deterioration of polyvinyl chloride may be caused, and thus there is a concern that the performance may be deteriorated. Further, since the temperature in the reactor increases as the chlorination reaction proceeds, it is preferable to control the temperature in the reactor to maintain the above range.

Meanwhile, UV irradiation is performed for the chlorination reaction of step 2, and particularly, in the present disclosure, a UV LED is used as a light source.

The UV LED may be provided in the reactor, and one or more UV LEDs may be provided as needed. Further, the position where the UV LED is disposed is not particularly limited as long as it is at a position where ultraviolet rays emitted from the UV LED can be irradiated to the reactant in the reactor. Preferably, the UV LED is disposed at an upper portion of the reactor so that ultraviolet rays from the UV LED can be efficiently irradiated onto the reactant.

The wavelength of the ultraviolet rays radiated from the light source is not particularly limited as long as it enables the chlorination reaction to proceed. Preferably, the ultraviolet wavelength is 290nm to 400 nm.

Meanwhile, the radiation angle of the light source is 45 ° to 110 °. The term "radiation angle" is intended to indicate the half-angle at which the cone of ultraviolet radiation now radiates from the source. If the radiation angle is less than 45 °, the optical power may be too high, and the properties of chlorinated polyvinyl chloride generated in the chlorination reaction may be deteriorated; if the radiation angle is greater than 110 deg., the optical power may be too low and the chlorination reaction may not sufficiently occur. Preferably, the radiation angle of the light source is 60 ° to 70 °. The radiation angle is determined according to the refraction angle of a quartz lens installed at the light source, and the required radiation angle can be controlled by changing the quartz lens.

Preferably, the light source has an optical power of 10W to 80W, more preferably 20W to 40W. Preferably, the UV intensity of the light source is 30 to 300mW/cm ² . Wherein, when a plurality of light sources are present, the optical power and the UV intensity of the light source refer to the sum of the optical power and the UV intensity of the plurality of light sources.

The distance between the light source and the reactant can be appropriately controlled in consideration of the light power and the UV intensity, and preferably, the distance is 10 cm or less.

Meanwhile, chlorinated polyvinyl chloride is prepared through the step 2 along with the progress of the chlorination reaction, and the reaction time of the chlorination reaction can be controlled by monitoring the chlorination degree of the polyvinyl chloride. Preferably, the reaction is preferably carried out until the chlorine content of the polyvinyl chloride becomes 62-69%, 64-68%, or 66-67.5%. Meanwhile, the chlorination reaction may be terminated by stopping the ultraviolet irradiation of the light source.

Further, the method of the present invention may further comprise the step of dehydrating and/or drying the chlorinated polyvinyl chloride prepared by the chlorination reaction.

As described in the following examples, when chlorinated polyvinyl chloride is prepared by the above-mentioned preparation method of the present invention, the preparation efficiency can be high, and at the same time, the properties of the prepared chlorinated polyvinyl chloride, such as the degree of discoloration, thermal stability, softening point, etc., can be improved.

Advantageous effects

As described above, according to the present invention, by using a UV LED as a light source and controlling a radiation angle, it is possible to improve the efficiency of preparing chlorinated polyvinyl chloride, and at the same time, to improve the properties of the prepared chlorinated polyvinyl chloride.

Detailed Description

Hereinafter, preferred embodiments will be presented to better understand the present invention, but these embodiments are presented only as illustrations of the present invention, and the scope of the present invention is not limited thereto.

Example 1

1) Examples 1 to 1

Polyvinyl chloride having a degree of polymerization of 1000 (average molecular chain length of 1000; K value of 67) was mixed with deionized water to prepare a 20 wt% polyvinyl chloride slurry, which was then introduced into a 5L reactor. In the reactor, an ultraviolet lamp (100W) was installed at the radius of the upper part of the reactor which was spaced apart from the center of the upper part of the reactor by 1/2 deg.F.

After the completion of the introduction, while stirring at a constant speed of 400 to 1000rpm, degassing was performed until the internal pressure of the reactor became-0.9 bar or more to remove oxygen inside the reactor. After degassing was complete, the temperature was raised to 40 ℃ and chlorine was then introduced.

If chlorine introduction is normally achieved, the UV lamp is operated to effect chlorination. Wherein the chlorination reaction is carried out under a reaction pressure of 0.5 to 4.0 bar and a reaction temperature of 50 to 95 ℃.

When the chlorine introduced during the chlorination reaction reaches a target value, the ultraviolet irradiation is stopped to terminate the reaction. After the reaction is terminated, sufficient nitrogen is used for removing residual unreacted chlorine, then chlorinated polyvinyl chloride slurry is dehydrated, and then the chlorinated polyvinyl chloride slurry is mixed with deionized water again to prepare slurry, and the slurry is neutralized by sodium carbonate, dehydrated and dried to prepare chlorinated polyvinyl chloride powder.

2) Examples 1-2 to 1-7

Chlorinated polyvinyl chloride was prepared in the same manner as in example 1-1, except that the UV LED lamp was changed as shown in table 1 below.

The properties of the chlorinated polyvinyl chloride prepared above were evaluated as follows:

(1) the process changes color: the Whiteness Index (WI) and the Yellowness Index (YI) were measured using a colorimeter.

(2) Thermal stability: a Mathis oven was used, the oven temperature was set to 195 ℃, the sample was fired at a rate of 23mm/10min, and the time for the sample to darken was measured.

(3) Vicat softening point: according to KS M ISO 306: 2015 was measured at 50 ℃ temperature rise rate under 50N load.

(4) Chlorine content: the CHNS element content was measured by an element analyzer.

The results are shown in table 1 below.

TABLE 1

Example 2

Chlorinated polyvinyl chlorides (examples 2-1 to 2-7) were prepared in the same manner as in example 1-1, except that a 200L reactor was used as the reactor and UV LED lamps were changed as described in table 2 below.

The properties of the chlorinated polyvinyl chloride prepared were evaluated in the same manner as in example 1, and the results are shown in Table 2 below.

TABLE 2

Claims

1. A process for preparing chlorinated polyvinyl chloride comprising the steps of:

2) the reaction was irradiated with UV while being stirred,

wherein the UV irradiation uses a UV LED disposed in the reactor as a light source, and the radiation angle of the light source is 45 DEG to 110 deg.

2. The method of claim 1, wherein the radiation angle is 60 ° to 70 °.

3. The method of claim 1, wherein the wavelength of the UV radiated from the light source is 290nm to 400 nm.

4. The method of claim 1, wherein the light source has an optical power of 10W to 80W.

5. The method of claim 1, wherein the light source has an optical power of 20W to 40W.

6. The method according to claim 1, wherein the UV intensity of the light source is 30-300 mW/cm ² 。

7. The method of claim 1, wherein a plurality of UV LEDs are disposed in the reactor.

8. The method of claim 1, wherein the distance between the light source and the reactant is equal to or less than 10 centimeters.

9. The method as claimed in claim 1, wherein the step 2 is performed until the chlorine content of the chlorinated polyvinyl chloride prepared becomes 62-69%.

10. The method of claim 1, wherein the method further comprises the step of dehydrating and/or drying the chlorinated polyvinyl chloride produced.