KR100495335B1 - Process for Recovery Polymer Using Direct Contact of Steam - Google Patents

Abstract

The present invention relates to a method for recovering a polymer using direct contact of steam, comprising: (1) introducing steam into a polymer solution supply line through a steam supply line, and supplying the polymer solution to a polymer solution supply line; (2) the steam and the polymer solution supplied to the polymer solution supply line are supplied to the first stripper after being stirred by an in-line mixer located at the rear of the supply line; (3) the agitated polymer solution and steam are supplied to the first stripper to pass through the second stripper, and the steam introduced to the second stripper passes through the respective devices in the opposite direction to the polymer solution; (4) The porous polymer mass formed after the solvent is removed from the first stripper is sent to the second stripper, and the vapor formed of the removed solvent and steam is sent to a decanter through a heat exchanger through a discharge line to condense. The next step of recovery; (5) removing the solvent remaining in the rubber-like polymer so that the rubber-like polymer mass delivered to the second stripper meets the process standard; And (6) the rubber-like polymer formed so that the residual solvent concentration to meet the process standard is made of a step of producing a porous pellet (pellet) through the dehydration, drying and extrusion process, the present invention is to separate the rubber-like polymer and solvent In the stripping process of recovering the polymer, energy required to remove the solvent, that is, steam consumption is reduced, and the amount of the dispersant that forms a crumb of an appropriate size during the recovery of the rubbery polymer can be drastically reduced.

Description

Process for Recovery Polymer Using Direct Contact of Steam}

The present invention relates to a method for recovering a polymer using direct contact of steam, and more particularly, by installing a steam supply line in a polymer solution supply line to directly contact a polymer solution with a small amount of steam, thereby efficiently controlling the temperature and pressure of the polymer solution. It is possible to drastically reduce the amount of steam required to vaporize the solvent in the polymer solution when stripping by easily removing the solvent in the polymer solution from the stripper, and significantly reduce the amount of the dispersant used to form a crumb of the appropriate size when recovering the rubber polymer. It relates to a polymer recovery method using a direct contact of steam that can be reduced.

In the preparation of the rubber polymer, an anion solution polymerization method using a transition metal catalyst or an organolithium catalyst is used. Since the produced polymer remains uniformly dissolved or suspended in a large amount of organic solvent, a process of separating and recovering the solvent and the produced polymer is necessary.

In general, there are various methods for recovering the polymer by separating the rubber polymer and the solvent, but the typical method is to add the polymer solution in high temperature water and remove the solvent by vaporizing the solvent with water vapor using steam to remove the crumb. A stripping process is used to recover the porous rubbery polymer having a constant size, called). In this method, a dispersant that serves as a surfactant and a dispersing aid to assist the role is used to prevent mass formation of the crumb and to disperse well in water.

In the case of recovering the rubber polymer in this way, it is composed of two strippers, primary and secondary, as disclosed in U.S. Patent No. 4411736, and a polymer solution containing a solvent to be recovered in the fluid flow. Stripping devices are often used which are designed such that the streams of steam which provide the necessary heat during recovery flow in counter currents. In the process of recovering the polymer by stripping, steam is filled with water in the stripper to maintain a constant S / C (the total mass of the contents of the stripping device excluding the mass of the rubber-like polymer in the stripping device / solvent). In addition to providing the amount of heat required for solvent removal, it is also used to maintain the temperature of the specific heat of water required for maintaining the S / C, rather than the former is much more heat consumed. As a method to compensate for this disadvantage, US Pat. No. 4,440,39, a concept of pre-stripper has been proposed. The proposed polymer recovery method is the concept of adding a pre-stripper device to the existing stripping process.In this case, the amount of solvent to be removed from the stripper is removed because a certain amount of solvent is removed from the polymer solution beforehand. Steam can be expected to be reduced due to the decrease of steam, but the condensed steam and polymer solution, which is put into the pre-stripper, are not easy to form a perfect homogeneous phase. Is difficult. In addition, in the steam stripping process proposed in US Pat. No. 4,44,363, comparing the solvent removal amount and energy consumption of the primary and secondary strippers, the amount of solvent removed from the primary stripper accounts for more than 85% of the total solvent amount. The amount of heat is much lower than that of the secondary stripper. To solve this problem, U.S. Patent No. 3763016 suggests a method of directly inserting part of steam into the primary stripper, but it requires more energy from the secondary stripper. Due to the nature of the process, it is not considered an effective process.

Therefore, the present inventors can reduce the steam in the polymer recovery method by putting a small amount of steam in the line supplied with the polymer solution to the stripper, and completed the present invention can significantly reduce the consumption of the dispersant used during steam stripping. It came to the following.

Accordingly, the present invention is provided to more efficiently solve the problems of the prior art as described above,

An object of the present invention is to provide a stripper device for recovering a solvent after preparing a rubber polymer using a solution polymerization of a polymer solution through direct contact between the polymer solution and steam by injecting a small amount of steam into a line where the polymer solution is supplied. By increasing the temperature and pressure efficiently, the solvent is easily removed from the polymer solution in the steam stripping process to provide a stripping process having a high energy efficiency compared with the existing process.

Another object of the present invention is to form a polymer seed in the line in which the polymer solution is injected due to the direct contact of the polymer solution and steam, thereby drastically reducing the consumption of the dispersing agent so that the polymer recovered during steam stripping has a certain size. To provide a way to do it.

The above and other objects of the present invention can be achieved by the present invention described below.

Polymer recovery method using the direct contact of steam according to the present invention (1) The polymer solution containing the solvent to be recovered is supplied to the polymer solution supply line, steam supply for the temperature and pressure rise of the polymer solution Introducing into the polymer solution supply line through a line; (2) the steam and the polymer solution supplied to the polymer solution supply line are supplied to the first stripper after being stirred by an in-line mixer located at the rear of the supply line; (3) The polymer solution and steam, which have been efficiently stirred, are supplied to the first stripper and sequentially passed through the second stripper. Steam, which provides the amount of heat required to remove the solvent in the polymer solution, is introduced into the second stripper and is separated from the polymer solution. Passing each device in the opposite direction; (4) The porous polymer mass formed after the solvent is removed from the first stripper is sent to the second stripper, and the vapor formed from the removed solvent and a small amount of steam is sent to a decanter through a heat exchanger through a discharge line to condense. And then recovered; (5) removing the solvent remaining in the rubber-like polymer so that the rubber-like polymer mass delivered to the second stripper meets the process standard; And (6) the rubber-like polymer formed so that the residual solvent concentration meets the process standard is made of a step of producing a porous pellet (pellet) through the dehydration, drying and extrusion process.

The rubber concentration of the liquid rubber-solvent mixture introduced into the first stripper is 10 to 30%. The temperature of the steam supplied through the steam supply line is 100 ~ 200 ℃. Steam or hot gas may be added to the steam supply line.

Steam is supplied to the polymer solution supply line supplied to the first stripper to operate the tube in the temperature of 80 ~ 140 ℃, pressure 2 ~ 8 Kgf / ㎠. The S / C of the first stripper and the second stripper is operated at 3 to 15%. The operating conditions of the first stripper is 70 ~ 90 ℃, the pressure is 1.1 ~ 2 Kgf / ㎠. The operating conditions of the second stripper is 80 ~ 120 ℃, the pressure is 2 ~ 6 Kgf / ㎠.

In a device for recovering a polymer by separating the polymer solution into a rubbery polymer and a solvent using conventional steam, the polymer recovery device according to the present invention is an in-line mixer and the polymer mounted on the rear end of the polymer solution supply line It further comprises a steam supply line 5 shown in FIG. 1 mounted to the solution supply line. The tube size of the steam supply line is 1 ~ 200 mm.

Hereinafter, the present invention will be described in detail.

Polymer recovery method using the direct contact of the steam according to the present invention is to improve the energy efficiency by reducing the amount of dispersant by putting a small amount of steam in the polymer solution supply line, porous having a suitable size called crumb It can be used in all the processes of recovering the rubber-like polymer of the as follows.

First, as the diene monomer forming the rubbery polymer using the steam stripping method of the present invention, 1,3 butadiene, isoprene, 2,3-dimethyl 1,3-butadiene, 1,3-pentadiene, 2-methyl 1 , 3-pentadiene, 1,3-hexadiene, 4,5-diethyl 1,3-octadiene, chloroprene and the like, but are industrially available 1,3-butadiene, isoprene, 1,3 -Pentadiene. Monomers which form copolymers with these include styrene, t-butyl styrene, α-methyl styrene, p-methyl styrene, divinyl benzene, 1,1-diphenyl styrene, N, N-diethyl p-amino ethyl styrene And vinyl pyridine and the like, and styrene and α-methyl styrene are particularly preferable.

In the method for producing a copolymer using such a monomer, a copolymer may be prepared using a hydrocarbon as an organic solvent and an organic lithium compound as an initiator, and then a coupling agent may be added as necessary. As the organic solvent, hydrocarbons such as hexane, heptane, octane, methylcyclopentane, cyclohexane, benzene, xylene and toluene are used. As the organic alkali metal compound which is a polymerization initiator, an organic lithium compound is preferable. As the organolithium compound, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, phenyl lithium, etc. are used, and as coupling agents, divinyl benzene, 1,2,4-trivinyl Benzene, epoxidized 1,2-polybutadiene, benzene 1,2,4-triisocyanate, diethyl oxalate, diethyl malonic acid, dioctyl adipic acid, dimethyl phthalate, methyl benzoate, ethyl benzoate, diethyl phthalate, diterephthalic acid Ethyl, diethyl carbonate, 1,1,2,2-tetrachloroethane, 1,4-bis (trichloromethyl) benzene, trichlorosilane, methyl trichlorosilane, butyl trichlorosilane, tetrachlorosilane, (dichloro Methyl) trichloro silane, tetra ethoxy silane, tetra chloro tin, 1, 3- dichloro 2- propane non etc. are mentioned.

The average molecular weight of the polymer is 50,000 to 700,000, preferably 100,000 to 650,000. Less than 50,000 cannot obtain a rubbery polymer of a suitable size, and if it is 650,000 or more, it is not preferable because the viscosity becomes high and the conveyance is difficult. The rubber polymer thus synthesized is steam stripped in the recovery method of the present invention to obtain a slurry in which rubber polymer having a particle diameter of 1 to 20 mm is dispersed in water. Here, as the dispersant, one or more selected from the group consisting of fatty acids (salts), chlorides, salts of polycarboxylic acids, polyoxyalkylene derivatives and phosphate esters are used, and as the salts of the polycarboxylic acids, maleic acid- The sodium salt, potassium salt, magnesium salt, etc. of an olefin copolymer are mentioned, The sodium salt of a maleic acid olefin copolymer is the most preferable. When the dispersant of the maleic acid-olefin copolymer is used, the crumb formation is excellent, but when the amount is increased, the adhesion decreases and the crumb slips in the extrusion process, which is a stripping process. In this case, the direction of reducing the dosage of the dispersant is preferable because it causes a decrease in temperature and pressure in the extruder, thereby providing a direct cause of the effective discharge of moisture in the product.

The particle diameter of the formed rubber polymer is 1 to 20 mm, preferably 2 to 10 mm. If it exceeds 20 mm, the solvent removal rate becomes slow, which is undesirable. If it is less than 1mm, it causes the loss of rubber-like polymer in the post process.

In the case of the first stripper and the second stripper, the concentration of the rubber-like polymer dispersed in water, that is, S / C, is about 0.1 to 20% by weight, preferably about 5 to 10% by weight. The reason is that when the weight is more than 10% by weight, it is difficult to obtain a rubbery polymer of a suitable size, which causes a problem that the rubbery polymer formed is attached to the wall of the stripper or the stirrer.

The present invention is described in detail below with reference to the accompanying drawings.

1 is a process chart showing a polymer recovery method using a direct contact of steam according to the present invention. FIG. 2 is a perspective view illustrating a steam supply line installed in a polymer solution supply line according to the present invention, and an in-line mixer for efficiently stirring the supplied steam and the polymer solution.

As shown in FIG. 1, the polymer solution containing the solvent to be recovered is injected into the first stripper 1 through the polymer solution supply line 3, so that the polymer solution can be easily removed from the polymer solution. Steam required to efficiently raise the temperature and pressure of the steam is supplied through the steam supply line (5). At this time, the in-line mixer 23 located at the rear end of the polymer solution supply line shown in FIG. 2 helps efficient contact between the introduced steam 22 and the polymer solution 21.

The steam, which maintains or raises the temperature of the stripper to provide the amount of heat required to remove the solvent of the polymer solution, is introduced into the second stripper through the steam line 10 installed in the second stripper 2. The temperature is 100 ~ 200 ^o C, the pressure is 2 ~ 16 Kgf / ㎠, the input amount is 10 ~ 400 parts by weight of the steam (5) supplied to the first stripper (1) relative to 100 parts by weight of the polymer solution The weight of the steam 10 supplied to the second stripper 2 is preferably 10 to 500. The flow direction of the polymer solution and steam in Figure 1, the steam moves in the direction 10 → 2 → 8 → 1 → 7, the polymer solution is moved to the opposite direction 3 → 1 → 9 → 11, the rubber-like polymer is recovered. The water necessary to maintain the S / C is recovered from the aftertreatment process and introduced into the first stripper 1 through the water supply line 4. The input amount of water and the polymer solution is 5 to 10% by weight, and the dispersing agent and the dispersing aid, which serve as surfactants, to prevent mass formation of the crumbs and disperse well in the water, are provided in the supply line (6). It is added to 0.0001 ~ 0.1 parts by weight based on 100 parts by weight of the rubber-like polymer through. The solvent and some steam vaporized and removed in the first stripper 1 are passed through the discharge line 7 and then sent to a decanter through a heat exchanger to condense and recovered. The crumb produced in the first stripper is transferred to the second stripper through the transfer line 9, and is removed through the recovery line 11 after removing the solvent such that the solvent content in the crumb is 2 wt% or less in the second stripper. .

At this time, the operating pressure and temperature in the polymer solution supply line 3 in contact with each stripper device and steam have a range shown in Table 1 below.

Operating conditions First stripper 2nd stripper Polymer Solution Supply Line Temperature (℃) 75 to 95 80 to 105 80-140 Pressure (Kgf / ㎠) 1 to 4 1 to 6 1 to 8

Hereinafter, although an Example and a comparative example demonstrate this invention in detail, the scope of the present invention is not limited to an Example.

EXAMPLES 1-4

In order to steam strip 20% by weight of the rubber-solvent mixture using cyclohexane as a solvent and SBS (Styrene-Butadiene-Styrene) copolymer as a rubber polymer, the steam supply line 5 shown in FIG. In the in-line stirring of the polymer solution and steam in the polymer solution supply line including the first and second strippers after the experiment under the conditions shown in Table 2, the rubber-like polymer mass according to the total steam consumption and dispersant input amount The coarse and fine content of the was measured and the results are shown in Table 2.

In the case of the first stripper, the temperature was set at the same conditions of temperature 89 ° C., pressure 1.3 Kgf / cm 2 S / C 7%, and in the case of the second stripper, temperature 110 ° C., pressure 1.5 Kgf / cm 2 S / C 7%.

[Comparative Example]

In order to steam strip 20% by weight of the rubber-solvent mixture with cyclohexane as solvent and SBS (Styrene-Butadiene-Styrene) copolymer as rubber, without steam inline (5) shown in FIG. After the first and second strippers were tested under the conditions as shown in Table 2 by the method of in-line stirring the polymer solution and steam, the coarse and fine of the rubber-like polymer mass according to the total steam consumption and dispersant input amount (fine) content was measured.

In the case of the first stripper, the temperature was set at the same conditions of temperature 89 ° C., pressure 1.3 Kgf / cm 2 S / C 7%, and in the case of the second stripper, temperature 110 ° C., pressure 1.5 Kgf / cm 2 S / C 7%.

By performing the recovery method and the existing process according to the present invention is shown in Table 2 below the level of reduction of steam consumption and dispersant input.

Comparative example Example 1 Example 2 Example 3 Example 4 Dispersant Input Level 1.00 0.89 0.51 0.24 0.97 In-line steam input (g / min) 0 58 63 70 136 Stripper Steam Input (g / min) 175 60 75 86 77 Inline steam input per ton of product 0 1.48 1.62 1.80 3.49 Inline total steam input per ton of product (MT / MT) 4.49 2.99 3.38 3.79 5.41 Coarse content (wt%) 9.2 6.0 2.79 10.50 2.5 Fine content (wt%) 8.74 6.0 12.46 1.17 31.9

Note) Coarse: If the size of the generated crumb is more than 10mm

Fine: If the size of the crumbs produced is less than 2mm

From the results of Examples 1, 2, and 3, it was proved that the steam consumption could be significantly reduced when stripping was performed through the steam in-line injection proposed in the present invention. In the case of Example 4, excessively increasing the steam input amount of the inline side was not only a product loss due to the increase in the fine content, it can be seen that it is not preferable in terms of energy efficiency. In the results of Examples 1 and 2, it can be seen that the size distribution of the crumb is determined by the inline steam input amount when the dispersant input is above a certain level.

As described above, when stripping is performed through the steam in-line injection proposed in the present invention, the steam consumption can be drastically reduced by up to 33% compared to the existing process, and the total loss amount (coarse content + fine). The amount of dispersant can be significantly reduced by more than 75% without increasing the content).

Polymer recovery method using the direct contact of the steam according to the present invention is applied to the recovery process after the solution polymerization of the rubber-like polymer, by directly contacting a small amount of steam with the polymer solution to effectively increase the temperature and pressure of the polymer solution stripper The solvent in the polymer solution can be easily removed, so the steam consumption required to evaporate the solvent in the polymer solution can be drastically reduced. .

While the invention has been described in detail above with reference to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope and spirit of the invention, and such modifications and variations fall within the scope of the appended claims. It is also natural.

1 is a process chart showing the overall process of the polymer recovery method using the direct contact of steam according to the present invention.

2 is a perspective view showing that the steam supply line according to the present invention is installed in the polymer solution supply line.

Brief description of the main symbols in the drawings

1: first stripper 2: second stripper

3: polymer solution supply line 4: water supply line

5: Steam Supply Line 6: Dispersant and Dispersion Aid Supply Line

7: Discharge Line 9: Transfer Line

10: steam line 21: polymer solution supply line

22: steam supply line 23: in-line mixer

Claims (10)

(1) introducing steam into the polymer solution supply line through a steam supply line, and supplying the polymer solution to the polymer solution supply line; (2) the steam and the polymer solution supplied to the polymer solution supply line are supplied to the first stripper after being stirred by an in-line mixer located at the rear of the supply line; (3) the agitated polymer solution and steam are supplied to the first stripper to pass through the second stripper, and the steam introduced to the second stripper passes through the respective devices in the opposite direction to the polymer solution; (4) The porous polymer mass formed after the solvent is removed from the first stripper is sent to the second stripper, and the vapor formed of the removed solvent and steam is sent to a decanter through a heat exchanger through a discharge line to condense. The next step of recovery; (5) removing the solvent remaining in the rubber-like polymer so that the rubber-like polymer mass delivered to the second stripper meets the process standard; And (6) rubber-like polymers formed so that the residual solvent concentration meets the process standards are prepared into porous pellets through dehydration, drying and extrusion processes; Polymer recovery method using the direct contact of the steam, characterized in that consisting of. The method of claim 1, wherein the rubber concentration of the liquid rubber-solvent mixture introduced into the first stripper is 10 to 30%. The method of claim 1, wherein the temperature of the steam supplied through the steam supply line is 100 ~ 200 ℃ characterized in that the polymer recovery method using the direct contact of steam. The method of claim 1, wherein steam or high temperature gas is introduced into the steam supply line. The direct contact of steam according to claim 1, wherein steam is supplied to the polymer solution supply line supplied to the first stripper to operate the tube at a temperature of 80 to 140 ° C and a pressure of 2 to 8 Kgf / cm2. Polymer recovery method using. The method of claim 1, wherein the S / C of the first stripper and the second stripper is operated at 3 to 15%. The method of claim 1, wherein the operating conditions of the first stripper is 70 ~ 90 ℃, the pressure is 1.1 ~ 1 Kgf / ㎠ characterized in that the polymer recovery method using the direct contact of steam. The method of claim 1, wherein the operating conditions of the second stripper is 80 ~ 120 ℃, the pressure is 2 ~ 6 Kgf / ㎠ characterized in that the polymer recovery method using the direct contact of steam. In the device for recovering the polymer by separating the polymer solution into a rubbery polymer and a solvent using steam, And an in-line mixer mounted to the rear end of the polymer solution supply line and a steam supply line mounted to the polymer solution supply line. delete