KR20220083381A - Method for preparation of chlorinated polyvinylchloride - Google Patents

Abstract

An object of the present invention is to provide a method for producing chlorinated polyvinyl chloride with improved thermal stability while minimizing a decrease in reaction efficiency by using a UV LED as a light source and changing the wavelength.

Description

Method for preparing chlorinated polyvinyl chloride {Method for preparation of chlorinated polyvinylchloride}

The present invention relates to a method for producing chlorinated polyvinyl chloride using an ultraviolet LED.

Chlorinated polyvinyl chloride has excellent heat resistance and is used in various fields such as pipes, films, and sheets. Chlorinated polyvinyl chloride is produced by reacting polyvinyl chloride with chlorine. In general, chlorine radicals must be generated in order for chlorine to react with polyvinyl chloride, and for this purpose, ultraviolet irradiation is required.

Until now, in the manufacture of chlorinated polyvinyl chloride, the most common method used for UV irradiation is to use a mercury UV lamp. Mercury UV Lamps are widely used because they are inexpensive and readily available, but they have low energy efficiency and short lifespan, requiring frequent replacement. In addition, ultraviolet rays are emitted in a radiation form from the mercury UV lamp, and accordingly, the ultraviolet rays do not sufficiently reach the reactants, which causes a problem in that the reaction efficiency is lowered.

Accordingly, research using UV LED Lamps with relatively high energy efficiency, low power consumption and long lifespan, is being conducted instead of mercury UV Lamps. However, there is a problem in that there is a trade-off relationship between reaction efficiency and thermal stability when UV LED lamps are used. Specifically, when a short wavelength with high energy is used, the reaction efficiency is increased but thermal stability is deteriorated, and when a long wavelength with low energy is used, there is a problem that the thermal stability is increased but the reaction efficiency is decreased.

Accordingly, the present inventors have made diligent efforts to solve the above problems, and as will be described later, by changing the wavelength band of the UV LED Lamp to a specific wavelength band during the chlorination reaction, the decrease in reaction efficiency can be minimized and thermal stability can be improved. By confirming, the present invention was completed.

Korean Patent Publication No. 10-2000-0051826

An object of the present invention is to provide a method for producing chlorinated polyvinyl chloride with improved thermal stability while minimizing a decrease in reaction efficiency by using a UV LED as a light source and changing the wavelength.

The present invention provides a process for producing chlorinated polyvinyl chloride:

1) adding a reactant containing polyvinyl chloride and chlorine into the reactor while irradiating ultraviolet rays of a first wavelength; and

2) agitating the reactant while irradiating ultraviolet rays of a second wavelength;

The ultraviolet irradiation of steps 1 and 2 uses an ultraviolet LED disposed in the reactor as a light source,

The value obtained by subtracting the first wavelength from the second wavelength is 10 nm or more and 50 nm or less,

A method for producing chlorinated polyvinyl chloride.

As described above, the present invention can improve thermal stability while minimizing a decrease in reaction efficiency when producing chlorinated polyvinyl chloride by using a UV LED as a light source and changing the wavelength.

Hereinafter, it will be described in more detail to help the understanding of the present invention.

Polyvinyl chloride can be reacted with chlorine to produce chlorinated polyvinyl chloride, and chlorinated polyvinyl chloride has improved heat resistance compared to polyvinyl chloride, and is used in various fields such as pipes, films, and sheets. In order to produce such chlorinated polyvinyl chloride, chlorine radicals must be generated, and ultraviolet irradiation is required for this purpose.

Conventionally, a mercury UV lamp has been used as a light source for UV irradiation, but there is a problem in that the energy efficiency is low and the lifespan is short, so that it needs to be replaced frequently. Accordingly, in the present invention, an ultraviolet LED is used as a light source, but in order to minimize a problem due to a trade-off between reaction efficiency and thermal stability, as described above, it is recommended to vary the wavelength irradiated in the chlorine input step and the reaction step after chlorine input. characterized.

Step 1 is a step of introducing a reactant containing polyvinyl chloride and chlorine into the reactor while irradiating ultraviolet rays of a first wavelength, and is a step of preparing the reaction of step 2 to be described later.

On the other hand, in the reactant input step of step 1, ultraviolet rays of a first wavelength are irradiated, and in particular, in the present invention, an ultraviolet LED is used as a light source.

One of the UV LEDs is disposed in the reactor, or a plurality of UV LEDs may be disposed as needed. In addition, as long as the ultraviolet light emitted from the ultraviolet LED can be irradiated to the reactants in the reactor, the arrangement position of the ultraviolet LED is not particularly limited. Preferably, it is preferably disposed above the reactor so that the UV light of the UV LED can be effectively irradiated to the reactant.

The first wavelength may improve the reaction efficiency of the initial reaction by irradiating a shorter wavelength having higher energy than the second wavelength irradiated in step 2 to be described later. Preferably, the first wavelength may be 300 nm to 400 nm, or 350 nm to 390 nm. Most preferably, the first wavelength may be 365 nm or 385 nm.

The reactor is not particularly limited as long as it is used for producing chlorinated polyvinyl chloride. In addition, the reactor may be provided with a device capable of controlling the conditions necessary for the reaction of the reactants by having a temperature control device, a pressure control device, and the like. In addition, since polyvinyl chloride and chlorine are generally reacted with stirring, a stirrer may be provided inside the reactor.

Among the reactants, polyvinyl chloride is preferably introduced into the reactor as an aqueous suspension, and accordingly, the stirrer is preferably provided at the lower end of the reactor. The aqueous polyvinyl chloride suspension may be prepared by mixing polyvinyl chloride with water and suspending the polyvinyl chloride, and the polyvinyl chloride in the suspension may be adjusted to 1 to 90 wt%. In addition, the suspension may be prepared first and put into the reactor, or polyvinyl chloride and water may be sequentially or together added to the reactor and then stirred.

In addition, chlorine among the reactants may be introduced into the reactor in a gaseous or liquid form. On the other hand, since chlorine is consumed by the chlorination reaction to be described later, chlorine may be additionally supplied to the reactor during the chlorination reaction process, and this process can be controlled by monitoring the chlorination degree of polyvinyl chloride.

In addition, the input amount of the reactant may be appropriately adjusted in consideration of the size of the reactor and the like.

Step 2 is a step of performing a chlorination reaction by stirring the reactants introduced into the reactor while irradiating ultraviolet rays of a second wavelength.

As for the temperature of the chlorination reaction, 50-95 degreeC is preferable. When the temperature of the chlorination reaction is less than 50 ° C., the chlorination reaction does not proceed sufficiently, and when it exceeds 95 ° C., the deterioration of polyvinyl chloride proceeds and there is a fear that physical properties may be reduced. In addition, since the temperature inside the reactor increases as the chlorination reaction proceeds, it is preferable to adjust the temperature inside the reactor to maintain the above range.

On the other hand, for the chlorination reaction of step 2, ultraviolet light of a second wavelength is irradiated, and an ultraviolet LED is used as a light source as in step 1. The description of the UV LED is the same as described above in step 1.

As the second wavelength, thermal stability may be improved by irradiating a long wavelength having lower energy than the first wavelength irradiated in step 1 described above. Preferably, the second wavelength may be 350 nm to 450 nm, or 380 nm to 410 nm. More preferably, the second wavelength may be 385 nm, 395 nm or 405 nm, and most preferably, the second wavelength may be 405 nm.

At this time, in order to minimize the decrease in efficiency due to the trade-off between reaction efficiency and thermal stability and to increase thermal stability, the difference between the first wavelength and the second wavelength is limited to a specific range. Specifically, the value obtained by subtracting the first wavelength from the second wavelength may be 10 nm or more and 50 nm or less, or 20 nm or more and 40 nm or less.

When the value obtained by subtracting the first wavelength from the second wavelength is less than 10 nm, the reaction efficiency is inferior and the effect of improving physical properties is insignificant. In addition, if a first wavelength that is too short is used so that the value obtained by subtracting the first wavelength from the second wavelength exceeds 50 nm, the energy of the first wavelength is too high, and deterioration of physical properties appears, and the first wavelength from the second wavelength is used If the second wavelength is too long so that the subtracted value exceeds 50 nm, the energy of the second wavelength is too low and the reaction time is greatly increased, resulting in disadvantages in terms of efficiency and economics. That is, when the value obtained by subtracting the first wavelength from the second wavelength is within the above range, the effect of improving the reaction efficiency and thermal stability according to the change in wavelength is excellent at the same time.

Preferably, the light output of the light source is 20 W to 160 W, more preferably 40 W to 100 W. In this case, when there are a plurality of light sources, the light output of the light source means the sum of the light output of the plurality of light sources.

The distance between the light source and the reactant may be appropriately adjusted in consideration of the light output and UV intensity, and preferably, the distance is 10 cm or less.

On the other hand, as the chlorination reaction proceeds through step 2, chlorinated polyvinyl chloride is prepared, and the reaction time of the chlorination reaction can be controlled by monitoring the degree of chlorination of the polyvinyl chloride. Preferably, it is preferable to adjust until the chlorine content of the chlorinated polyvinyl chloride to be prepared becomes 62 to 69%, 64 to 68%, or 66 to 67.5%. On the other hand, the chlorination reaction may be terminated by terminating the ultraviolet irradiation through the light source.

In addition, the present invention may further include the step of dehydrating and/or drying the chlorinated polyvinyl chloride produced through the chlorination reaction.

Hereinafter, it will be described in more detail to help the understanding of the present invention. However, the following examples only illustrate the present invention, and the content of the present invention is not limited by the following examples.

[Example]

Comparative Example 1

A 20 wt% slurry was prepared by mixing polyvinyl chloride having a degree of polymerization of 1000 (average molecular chain length of 1000 pieces; K Value 67) and deionized water, and this was put into a 200 L reactor. When the input was completed, degassing was performed while stirring at a constant speed of 450 rpm until the internal pressure of the reactor became -0.9 bar or more. After degassing, when it was confirmed that the internal pressure of the reactor was maintained at -0.9 bar for 5 minutes or more, the temperature of the reactor was increased. When the reaction temperature reached 40 ℃, chlorine input was started and two UV lamps (200W*2, dominant wavelength: 365 nm, mercury lamp) were operated to carry out the chlorination reaction. At this time, the reaction pressure was maintained at 2.0 bar, and the chlorination reaction was performed at a reaction temperature of 70 °C.

When the input chlorine reached the target value, the chlorination reaction was terminated. After the reaction was completed, the unreacted residual chlorine was removed with sufficient nitrogen, and the resulting chlorinated polyvinyl chloride slurry was dehydrated, then a slurry was prepared again with deionized water, neutralized using a neutralizing agent (sodium carbonate), and then dehydrated and dried to obtain a powdery form. of chlorinated polyvinyl chloride was prepared.

Comparative Example 2

Chlorinated polyvinyl chloride was prepared in the same manner as in Comparative Example 1 except that a UV LED lamp (5W*80, dominant wavelength: 365 nm) was operated after chlorine was added.

Comparative Example 3

Chlorinated polyvinyl chloride was prepared in the same manner as in Comparative Example 1 except that a UV LED lamp (1W*80, dominant wavelength: 365 nm) was operated after chlorine was added.

Comparative Example 4

Chlorinated polyvinyl chloride was prepared in the same manner as in Comparative Example 1 except that a UV LED lamp (1W*80, dominant wavelength: 385 nm) was operated after chlorine was added.

Comparative Example 5

Chlorinated polyvinyl chloride was prepared in the same manner as in Comparative Example 1, except that a UV LED lamp (1W*80, dominant wavelength: 405 nm) was operated after chlorine was added.

Example 1

After chlorine input, UV LED Lamp (1W*80, main wavelength: 365 nm) is operated and when chlorine input is finished, UV LED Lamp (1W*80, main wavelength: 405 nm) is operated and maintained until the end of the reaction. Chlorinated polyvinyl chloride was prepared in the same manner as in Comparative Example 1.

Example 2

After chlorine input, UV LED Lamp (1W*80, main wavelength: 365 nm) is operated and when chlorine input is finished, UV LED Lamp (1W*80, main wavelength: 405 nm) is operated and maintained until the end of the reaction. and chlorinated polyvinyl chloride was prepared in the same manner as in Comparative Example 1.

Example 3

After chlorine input, the UV LED Lamp (1W*80, dominant wavelength: 385 nm) is operated and when chlorine input is finished, the UV LED Lamp (1W*80, dominant wavelength: 405 nm) is operated and maintained until the reaction is completed. and chlorinated polyvinyl chloride was prepared in the same manner as in Comparative Example 1.

[Experimental example]

Each of the physical properties of the prepared chlorinated polyvinyl chloride was evaluated by the following method, and is shown in Table 1 below.

(1) Process coloration: Whiteness (White Index, WI) and yellowness (Yellow Index, YI) were measured using a colorimeter.

(2) Thermal stability: Using a Mathis Oven, the oven temperature was set to 195° C. and the sample was ejected at a rate of 23 mm/10 min, and the time point at which the color changed to black was measured.

(3) Vicat softening point: In accordance with KS M ISO 306:2015, it was measured at a temperature increase rate of 50 °C and a load of 50 N.

(4) Chlorine content: CHNS element content was measured using an elemental analyzer.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Example 1 Example 2 Example 3 reaction conditions Lamp output (W/EA) 200 5 One One One One One One Lamp total power (W) 400 400 80 80 80 80 80 80 Number of Lamps (pcs) 2 80 80 80 80 80 80 80 Lamp wavelength (nm) 365 365 365 385 405 365 → 405 365→
385 385→
405 Chlorination reaction time (min) 123 83 114 127 143 115 115 130 Total reaction time (min) 181 123 185 201 220 187 185 208 Properties processing coloring WI 8.6 10.1 14.4 15.1 17.0 17.1 14.9 17.4 YI 21.9 21.7 20.6 19.9 19.0 19.0 20.3 18.8 Thermal stability (min) 148 144 166 170 185 187 170 190 Vicat softening point (℃) 114.6 114.5 116.4 116.7 117.2 117.7 116.5 117.6 Chlorine content (wt%) 67.3 67.2 67.3 67.3 67.3 67.3 67.3 67.3

Looking at the results of Table 1, when a UV LED lamp of 365 nm single wavelength having high energy is used (Comparative Example 2), there is an advantage in that the reaction efficiency increases due to the high light efficiency, which is a characteristic of the LED, while the generated chlorination It can be confirmed that the problem of lowering the physical properties of polyvinyl chloride occurs. Conversely, when a 405 nm single-wavelength UV LED lamp having a relatively low energy is used (Comparative Example 5), the physical properties of the produced chlorinated polyvinyl chloride are improved, but the reaction efficiency is lowered and the reaction time is prolonged.

On the other hand, in the case of an embodiment of the present invention, in order to minimize the decrease in reaction efficiency and at the same time improve the physical properties of the generated chlorinated polyvinyl chloride, from the time of chlorine input until the end of the chlorine input and the reaction time after the chlorine input is completed UV rays of different wavelengths were irradiated. In the chlorine input process, a short wavelength UV LED lamp with relatively high energy is used to increase the reaction efficiency, and after chlorine input, a UV LED lamp with relatively low energy is used until the reaction is completed to prevent deterioration of properties. Confirmed.

Claims (11)

1) adding a reactant containing polyvinyl chloride and chlorine into the reactor while irradiating ultraviolet rays of a first wavelength; and
2) stirring the reactant while irradiating ultraviolet rays of a second wavelength,
The ultraviolet irradiation of steps 1 and 2 uses an ultraviolet LED disposed in the reactor as a light source,
The value obtained by subtracting the first wavelength from the second wavelength is 10 nm or more and 50 nm or less,
A method for producing chlorinated polyvinyl chloride.
According to claim 1,
The first wavelength is 300 nm to 400 nm,
A method for producing chlorinated polyvinyl chloride.
According to claim 1,
The first wavelength is 350 nm to 390 nm,
A method for producing chlorinated polyvinyl chloride.
The method of claim 1,
The second wavelength is 350 nm to 450 nm,
A method for producing chlorinated polyvinyl chloride.
According to claim 1,
The second wavelength is 380 nm to 410 nm,
A method for producing chlorinated polyvinyl chloride.
According to claim 1,
The value obtained by subtracting the first wavelength from the second wavelength is 20 nm or more and 40 nm or less,
A method for producing chlorinated polyvinyl chloride.
According to claim 1,
The light output of the light source is 20 W to 160 W,
A method for producing chlorinated polyvinyl chloride.
According to claim 1,
The light output of the light source is 40 W to 100 W,
A method for producing chlorinated polyvinyl chloride.
According to claim 1,
The ultraviolet LED is arranged in plurality in the reactor,
A method for producing chlorinated polyvinyl chloride.
According to claim 1,
The step 2 is carried out until the chlorine content of the chlorinated polyvinyl chloride to be prepared is 62 to 69%,
A method for producing chlorinated polyvinyl chloride.
The method of claim 1,
Further comprising the step of dehydrating and / or drying the prepared chlorinated polyvinyl chloride,
A method for producing chlorinated polyvinyl chloride.