JP2006274101A - Method for recovering vinyl chloride resin and recovery treatment equipment therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an efficient recovery method for recovering a vinyl chloride resin by dissolving in a solvent a sheet-like waste product containing the vinyl chloride resin to which stains such as soil difficult to remove are sticking. <P>SOLUTION: The method for recovering the vinyl chloride resin from the sheet-like waste product comprises a washing step for throwing the sheet-like waste product into a washing tub, feeding water at 40-70°C and washing the waste product, a dissolution step for dissolving the washed sheet-like waste product in a solvent in which the vinyl chloride resin is soluble to obtain a vinyl chloride resin-containing solution, a separation step for separating insoluble from the vinyl chloride resin-containing solution, and a recovery step for recovering the vinyl chloride resin from the solution from which the insoluble has been removed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and a recovery processing facility for recovering vinyl chloride resin from waste, and more particularly to a recovery method and a recovery processing facility from sheet-like waste containing vinyl chloride resin.

  Since vinyl chloride resins such as vinyl chloride resin and vinylidene chloride resin are excellent in processability and inexpensive, they can be used in various applications like other general-purpose polymers such as polyester and polyolefin (for example, polyethylene and polypropylene). in use. However, such general-purpose polymers are mass-produced not only in the field of basic materials having a long life cycle, but also as commodity materials having a short service life such as daily necessities, and therefore, environmental pollution associated with mass disposal is a problem.

  Wastes mainly composed of vinyl chloride resin include, for example, household electric leisure sheets, ground sheets, agricultural vinyl sheets used for house cultivation, and construction work, in addition to waste electric wire coverings and wallpaper for building materials. For example, a cover sheet for a building on site. Most of such waste is disposed of by landfill or incineration, but vinyl chloride resin cannot be decomposed in nature, and as is well known, the cause of dioxin formation by incineration Because it is one of the substances, it is necessary to consider the environmental impact.

For this reason, various recovery methods for recovering and reusing vinyl chloride resin from wastes mainly composed of vinyl chloride resin have been studied. For example, in addition to mechanical recovery methods such as pulverization and centrifugation, recently, a method has been studied in which waste is dissolved in a solvent in which vinyl chloride resin can be dissolved, and vinyl chloride resin is recovered from the solution ( For example, Patent Documents 1 to 3).
JP-A-11-310660 Special table 2003-510436 gazette JP 2004-292549 A

  The recovery method using the above solvent is preferable because it is highly safe and can collect vinyl chloride resin with high purity. However, when the waste is in the form of a sheet, dirt easily adheres to it during use. Since something like a vinyl sheet is used outdoors, the adhesion of the soil is bad and the deposit cannot be easily removed. If such deposits are present, there is a problem that soil matter is mixed into the recovered vinyl chloride resin, leading to deterioration of the quality of the vinyl chloride resin. For this reason, it is considered that the metal in the deposit is removed by magnetic treatment such as a magnet before melting, but the non-metallic soil cannot be removed sufficiently. In addition, in the recovery method using a solvent, insoluble matters generated during the dissolution treatment are separated. However, a large amount of insoluble matters are generated in a sheet-like waste having excessive deposits, and clogging occurs in the separation step. Therefore, the processing efficiency is lowered. Furthermore, it is conceivable to wash the sheet-shaped waste in advance before dissolution, but it is difficult to sufficiently remove the soil that is firmly attached to the sheet even if the soil with weak adhesion can be removed by simple washing. It is. In the case of collecting a high-purity vinyl chloride resin with a small amount of impurities, such a hard-to-remove deposit greatly affects the final quality. In particular, when recycling vinyl chloride resin, add a colorant according to the application and use it as a product after coloring, but when the soil is mixed in the recycled product, the recycled product looks bad and is colored. It is necessary to add a large amount of the agent. For this reason, there is a problem that the use of the recycled product is limited, or the cost is increased by adding a large amount of the colorant.

  Also, in the case of sheet-like waste, unlike waste wire coating that is processed in the form of chips, the concentration of the solution in the solvent cannot be increased due to its bulkiness, and the sheet-like waste aggregates in the solution and has solubility. There has been a problem that the processing efficiency of the waste is lowered, for example, it is lowered.

  The present invention has been made in view of the above circumstances, and its purpose is to dissolve a sheet-like waste containing a vinyl chloride resin to which dirt such as soil matters adheres and which is difficult to remove, in a solvent. An object of the present invention is to provide an efficient recovery method and recovery processing facility for recovering a resin with high purity.

  The method for recovering vinyl chloride resin from sheet waste containing a vinyl chloride resin for solving the above-mentioned problems of the present invention means that the sheet waste is put into a washing tank and the temperature is 40 to 70 ° C. A washing step of supplying water for washing, a washing step of dissolving the washed sheet waste in a solvent in which the vinyl chloride resin can be dissolved to obtain a vinyl chloride resin-containing solution, and the vinyl chloride The present invention includes a separation step of separating an insoluble matter from a resin-containing resin solution and a recovery step of collecting the vinyl chloride resin from the solution from which the insoluble matter has been removed. The sheet-like waste treated in advance in the washing step as described above can greatly reduce the deposits derived from soil. For this reason, when it melt | dissolves in a solvent, mixing of an insoluble matter can be suppressed, the efficiency in a separation process can be achieved, and the purity of the recovered vinyl chloride resin can be increased.

  Moreover, it is preferable that the present invention further includes a step of cooling and cutting the washed sheet-like waste after the washing step and before the dissolving step. By providing such a cooling and cutting step, the sheet-like waste can be made into small pieces of fluff, and the processing efficiency can be improved.

  In addition, the present invention further includes a granulation step after the washing step and before the dissolution step, after the washed sheet-like waste is heated and melted, and granulated to obtain a vinyl chloride resin-containing granulated product. It is preferable. By heating and melting the sheet waste and granulating, the specific gravity of the processed product can be increased, and the processing efficiency can be improved. In addition, by using a granulated product, the concentration of the solution in the dissolution process can be increased compared to that of sheet waste, and in the case of sheet waste, only about 10 to 15% by weight can be dissolved in the solution. In contrast, the granulated product can be treated at 20% by weight or more.

  The present invention preferably further comprises a dehydration step after the washing step and before the granulation step. By providing such a dehydration step before granulation, heating and melting in the granulation step can be performed smoothly.

  The recovery step of the present invention includes a step of depositing a vinyl chloride resin by bringing hot water and / or steam (hereinafter sometimes simply referred to as “hot water”) into contact with the solution from which the insoluble matter has been removed. Is preferred. By such a recovery step, the vinyl chloride resin can be recovered with high purity.

  Moreover, it is preferable that the said collection | recovery process of this invention is equipped with the process of adding the non-solvent of vinyl chloride resin to the solution which removed the said insoluble matter, and depositing vinyl chloride resin. The vinyl chloride resin can be recovered with high purity by such a recovery process.

  In addition, the present invention is a vinyl chloride resin recovery treatment facility comprising the above recovery method. According to the recovery processing facility of the present invention, vinyl chloride resin can be efficiently recovered from sheet waste with high purity.

  According to the collection method of the present invention, even when a sheet-like waste containing a vinyl chloride resin, which is difficult to remove due to soil dirt or the like being attached thereto, is treated in the washing step. Since it is washed with washing water at ˜70 ° C., it is possible to efficiently remove the deposits derived from the soil that the sheet-like waste is softened and firmly adhered. Therefore, by using this sheet-like waste in a method of recovering by a dissolving step, vinyl chloride resin with less impurities can be recovered efficiently.

(Embodiment 1)
FIG. 1 is a flowchart showing a recovery process from a cleaning process according to the first embodiment. Examples of the raw material containing, as a main component, a vinyl chloride resin such as a vinyl chloride resin or a vinylidene chloride resin treated in the present invention include sheet-like waste such as agricultural vinyl sheets and construction site sheets. Such sheet-like waste contains a large amount of deposits due to soil, etc. on the surface of the sheet or inside the sheet, and when it is poured into a solvent and dissolved, a large amount of insoluble matter is generated, resulting in extremely low processing efficiency. At the same time, the purity of the recovered vinyl chloride resin decreases. For this reason, in this invention, it melt | dissolves through the washing | cleaning process of a predetermined condition. The size of the sheet-like waste is not particularly limited, but if a long sheet or the like is too large, cleaning cannot be performed efficiently, and the cleaning apparatus becomes large. On the other hand, if the sheet-like waste is too small, the cleaning action may be reduced due to water and friction. Therefore, it is preferable to cut the sheet waste to a size of about 100 to 400 mm square. For this cutting, a conventionally known sheet cutting machine can be used. In addition, even if it is a sheet-like waste with a small amount of deposits, it can be preferably used to reduce the amount of impurities in the vinyl chloride resin recovered by using the present invention.

  The sheet-like waste obtained as described above is put into a cleaning device for cleaning, and the amount of deposits is reduced. As a condition in the cleaning process, it is important to control the water temperature within a certain range, particularly because the temperature control greatly affects the amount of deposits removed. That is, the vinyl chloride resin used in agricultural vinyl sheets and the like is a vinyl chloride resin having a degree of polymerization of about 1,100 to 1,300, and such a vinyl chloride resin is softened at 40 ° C. or higher. Come on. By this softening, not only the soil attached to the surface but also the soil that has entered the interior is easily washed away by the water flow, and a large amount of attached matter can be efficiently removed. According to the study by the present inventors, it has been confirmed that there is an effect of removing adhering substances more than three times as much as in the case of using room temperature water. On the other hand, if the temperature of the washing water becomes too high, the sheet will be too soft, and deposits will be taken into the sheet and the removal amount will be reduced. For this reason, the temperature of water used for washing is preferably 40 to 70 ° C, and most preferably 40 to 60 ° C.

  In addition, the residence time of the sheet-like waste in the apparatus in the cleaning process is preferably 10 to 50 seconds, and the amount of water is preferably 0.1 to 0.5 t per 1 t of waste. If the residence time is less than 10 seconds or the amount of water supply is less than 0.1 t, the contact time between the waste and the water is too little, and the water does not reach the entire waste and can be washed sufficiently. There is no tendency. On the other hand, the removal amount increases by increasing the residence time or increasing the amount of water, but even if it is too long, there is not much difference in the cleaning effect, which is not economical.

  When the vinyl chloride resin is collected by the dissolution treatment of the present invention, the standard of deposits in the sheet-like waste after washing obtained above is 0.05 t or less per 1 t of waste. preferable. If the amount of the adhering material is reduced to this level, the sheet can be sufficiently shortened in the subsequent processing step, and the recovered vinyl chloride resin is less than 0.5% by weight of impurities that are weakly colored by soil. Since it can be reduced, it can be used as a recycled vinyl chloride resin in various applications.

  Next, although the washed sheet-like waste obtained as described above is subjected to a dissolution treatment, the sheet-like waste can be preliminarily cut into a fluff of 50 mm square or less.

  For the dissolution treatment, a solvent capable of dissolving the vinyl chloride resin contained in the sheet is used. Specifically, for example, a polar solvent, particularly a ketone solvent, can be suitably used, whereby the vinyl chloride resin can be selectively dissolved even from waste containing a polymer such as polyolefins. In addition, when a ketone solvent is used, a high molecular weight vinyl chloride resin can be processed. Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, and cyclohexanone. In the present invention, ethers such as tetrahydrofuran with high solubility of vinyl chloride resin, water-soluble amide compounds such as N-methylpyrrolidone, and water-soluble lactone compounds such as γ-butyrolactone can also be used. The solvent used can be appropriately selected depending on the solubility of the vinyl chloride resin contained in the waste, the treatment method for recovering the vinyl chloride resin, and the like.

  Although the temperature which heats a solvent at the time of a melt | dissolution process changes with kinds of solvent to be used, if it is less than the temperature which a solvent volatilizes, it will not specifically limit, What is necessary is just to control temperature in the range which can be operated safely. The method for dissolving is not particularly limited, and the washed sheet waste can be put into a container in advance, and a solvent can be added to the container and heated and stirred, or the waste can be mixed with the preheated solvent. You may stir.

  Next, the obtained solution is separated into a dissolved substance such as a vinyl chloride resin and an insoluble substance insoluble in a solvent. The means for separating is not particularly limited, and a known method such as a screen, centrifugal separation or precipitation can be used.

  The solution from which insoluble matter has been separated is then transferred to a recovery step. In this recovery step, a conventionally known recovery method can be used. For example, (a) a method in which hot water and / or steam is brought into contact with the solution to evaporate the solvent and the vinyl chloride resin is precipitated and recovered by precipitation; (b) chlorination is performed by evaporating the solvent by heating the solution. For example, a method in which a vinyl resin is deposited, melted by heating, and recovered can be used. FIG. 1 utilizes the recovery method including the precipitation step (a) among the above, and this method is preferable because recovery of the vinyl chloride resin and evaporation of the solvent can be performed simultaneously. The following is an example of the processing method used for this collection method. In addition, as said method, the method as described in Unexamined-Japanese-Patent No. 11-310660 etc. can be referred, for example.

  First, when the solution from which the insoluble matter has been separated is brought into contact with hot water, the solubility of the vinyl chloride resin in the solvent is drastically reduced, and the solvent in the solution is volatilized. It can be deposited as a precipitate. Then, the vinyl chloride resin can be recovered by separating the precipitate and removing the residual solvent from the solution containing the particulate vinyl chloride resin.

  In the present invention, the method of bringing the solution into contact with hot water or the like is not particularly limited, but a method of injecting hot water or the like into the solution is recommended. If this method is used, even when the injection amount of the solution dissolving the vinyl chloride resin is not constant or when the operation is suddenly stopped, the vinyl chloride resin does not temporarily precipitate, Operation is possible without strictly controlling the amount of solution injected.

  In the present invention, the vinyl chloride resin can be recovered by separating the vinyl chloride resin precipitated from the solution from the residual solvent or the like. The separation method is not particularly limited, and a known method can be employed. Examples thereof include a screen and centrifugation. And the isolate | separated water can be returned to a precipitation process as needed.

  Next, an embodiment of a vinyl chloride resin recovery treatment facility that can achieve the object of the present invention will be described. FIG. 2 is a schematic view of a cleaning apparatus 1 used in the cleaning process of the present invention, and FIG. 3 is a dissolution, separation, and recovery process for dissolving the washed sheet waste and recovering the vinyl chloride resin from the solution. It is the schematic which shows each structure.

  The cleaning device 1 in FIG. 2 is a two-tank horizontal cleaning device that includes an outer tub 12 and an inner tub 13, and the inner tub 13 is a drum that is rotatable in the vertical direction so that efficient cleaning can be performed. Further, a protrusion 14 is formed on the inner wall surface of the inner tub 13, and the protrusion 14 passes the inside of the sheet-like waste (not shown) input from the input port 17 by the transfer means L <b> 1 to the output port 18. It is formed in a spiral shape to be conveyed.

  A water pipe 15 is introduced into the inner tank 13 and has a structure for supplying hot water 16 controlled to 40 to 70 ° C. from the pipe L2 to the inside. Waste is cleaned. Although not shown, the wall of the inner tub 13 has a large number of holes, and hot water 16 is supplied to the inside of the cleaning device, and after cleaning the sheet waste, sewage is discharged from the holes in the wall. It is supposed to be drained. The rotational speed of the drum in this embodiment may be appropriately selected so as to ensure the above-described residence time, and is not particularly limited, but is preferably 10 to 30 rpm. In this embodiment, the outer tank 12 and the inner tank 13 have a two-tank structure, but it is not always necessary to have two tanks. In addition, the cleaning device can have a predetermined residence time and is not particularly limited as long as it has a structure capable of supplying water for cleaning.

  The sheet-like waste cleaned by the above-described cleaning process is then conveyed to the dissolution process. FIG. 3 mainly includes a dissolution apparatus 2, a separation apparatus 3, a precipitation apparatus 4, a transfer belt disposed between them, a pipe, and the like.

  The sheet-like waste cleaned by the above-described cleaning process is removed from the water, and then charged into the dissolving device 2 by the transfer means L3. The dissolving device 2 includes a pipe L4 for supplying a solvent capable of dissolving the vinyl chloride resin and a stirrer 21. The charged sheet-like waste is stirred and mixed with a solvent to dissolve the vinyl chloride resin to form a slurry-like solution 22. At this time, in order to promote the melting, the melting device 2 having a heating device such as a heater is used. The solution can further dissolve the vinyl chloride resin completely using a static mixer or the like.

  Next, the above solution is introduced into the separation device 3 through the pipe L5, the insoluble matter is discharged from the pipe L6, and the dissolved matter is supplied to the precipitation device 4 through the pipe L7. As this separation device, for example, a separation device such as a screen can be used.

  The precipitation apparatus 4 includes a stirrer 41 and a pipe L8 for supplying hot water or the like into the apparatus as in the dissolution apparatus 2. By supplying this hot water or the like into the solution 42, the amount of the vinyl chloride resin dissolved in the solvent decreases while the solvent evaporates, so that a particulate precipitate is deposited. The evaporated solvent is condensed through the pipe L9 as desired, and is reused as the solvent in the dissolving apparatus 2.

  The solution containing the precipitated vinyl chloride resin is sent to a pump (not shown) via the pipe L10, and further introduced into a separator 43 for separating the residual solvent and the vinyl chloride resin. For example, a filter or a centrifuge can be used as the separator 43. Since the residual solvent is mainly composed of water, it is reused in the precipitation device 4 after performing distillation or the like as desired via the pipe L11.

  Then, the recovered vinyl chloride resin is transferred through the pipe L12 and, if necessary, is subjected to a drying process to obtain a regenerated vinyl chloride resin.

  The vinyl chloride resin contained in the sheet-like waste can be efficiently recovered with high purity through a series of steps including the above-described washing step, dissolving step, separation step, and recovery step.

(Embodiment 2)
In the present invention, it is also preferable to provide a step of cooling and cutting the sheet-like waste washed after the washing step and before the dissolving step in the first embodiment.

  When the sheet-like waste is large, it is preferable to cut the sheet-like waste in advance into smaller fluffs because the handling in the melting step is complicated and the apparatus becomes large. Also, when performing granulation according to Embodiment 3 to be described later, it is preferable to use small pieces because melting becomes quicker.

  FIG. 4 is a diagram showing the flow of the present embodiment, which is the same as that of the first embodiment except that the cooling and cutting steps are provided after the cleaning step. For this reason, the description of the same parts as those of the first embodiment is omitted, and the cooling and cutting processes are described below.

  Since the sheet-like waste is heated and softened with warm water at the time of washing in the washing step, the machine is likely to be bitten if it is directly put into a crusher to produce a small piece of fluff. For example, in the case of a sheet-like waste heated to 30 ° C. or more in the vinyl sheet for agriculture, biting of the apparatus was confirmed at the time of crushing. For this reason, by cooling after washing, even a soft and difficult-to-crush sheet such as an agricultural vinyl sheet can be efficiently crushed. In this case, the washed sheet-like waste can be cooled by allowing it to stand at room temperature. However, in order to reduce the processing speed, it is cooled to room temperature to about 10 ° C. by air cooling or water cooling after the washing step. Is preferred.

  Next, the cooled sheet-like waste is cut. For the cutting, a crusher used to produce a normal fluff can be used. The size of the fluff is preferably 50 mm square or less. In this cutting process, it is preferable to perform cutting while adding water in order to remove contaminants such as soil adhering to the sheet-like waste and improve the washing performance.

(Embodiment 3)
In the first embodiment of the present invention, it is also preferable to granulate the sheet-like waste that has been washed after the washing step and before the dissolving step. With such granulation, the solution concentration could only be increased up to 15% by weight when treated as a sheet waste in the dissolution process, but it can be used even at a concentration of 20% by weight or more by granulation. It becomes possible to further improve the efficiency of the recovery process.

  FIG. 5 is a diagram showing a flow of the present embodiment, which is the same as that of the first embodiment except that a granulation step for heating and melting the sheet waste and granulating is provided after the cleaning step. . For this reason, description is abbreviate | omitted about the same part as Embodiment 1, and a granulation process is described below.

  In the granulation step, the washed sheet waste is first heated and melted. The melting temperature is preferably 120 to 150 ° C. If the temperature is too low, it will not be in a molten state and it will be difficult to obtain a uniform granulated product. On the other hand, if the melting temperature is too high, decomposition tends to occur as a characteristic of the vinyl chloride resin, and there is a problem that hydrogen chloride gas or the like is generated. Although the melting time depends on the type of the vinyl chloride resin, it is preferably 2 to 20 minutes when the processing amount per batch is 10 to 30 kg. Next, the melt is granulated. At that time, the melt is granulated from the melted state, further cooled and solidified to obtain a vinyl chloride resin-containing granulated product. As cooling conditions, it is preferable to rapidly cool to 60 ° C. or less in 2 to 5 minutes.

  As an apparatus for melting and granulating the sheet-like waste of the present invention, a Henschel mixer, an add-on mixer, or the like, which is used when a synthetic resin is usually produced, can be used. When such an apparatus is used, melting and granulation can be performed in the same mixer. And after granulation, it supplies to cooling devices, such as a cooler mixer, and a vinyl chloride resin containing granulated material can be obtained by cooling and solidifying.

Vinyl chloride resin containing granulated product of the present invention is a particle diameter at 10mm or less, an apparent specific gravity of 0.1 g / cm ³ or more, preferably it is desirable that the 0.3 to 0.5 g / cm ^3. The apparent specific gravity is measured according to the measuring method described in JIS K 6720-2. By making such a granulated product with an apparent specific gravity, the dissolution rate in the solvent in the dissolution step can be dissolved at a speed comparable to that in the sheet form, and the solution concentration can be 20% by weight or more. it can. Therefore, the processing efficiency of the entire recovery process can be significantly increased compared to the case of a sheet form. If the apparent specific gravity is further increased, the solution concentration in the dissolving step can be increased, but it tends to require a long time to completely dissolve the granulated product.

(Embodiment 4)
In the third embodiment, it is also preferable to provide a dehydration step after the washing step and before the granulation step. By providing such a dehydration step before the granulation step, heating and melting for granulation can be performed efficiently.

  FIG. 6 is a diagram showing a flow of the present embodiment, which is the same as that of the first embodiment except that a dehydration process and a granulation process are provided after the cleaning process. For this reason, the description of the same parts as those in Embodiments 1 and 3 is omitted, and the dehydration process will be described below.

  In the dehydration process, first, water adhering to the washed sheet-like waste is dehydrated by a dehydrator. At this time, it is preferable to perform two steps of dehydration washing and dehydration. By performing dehydration washing, the deposits of sheet-like waste can be further reduced. Normal temperature water can be used for this cleaning. In the dehydration step after dehydration washing, water can be removed by, for example, centrifugal dehydration. The amount of water in the sheet-like waste thus obtained is set to 0.1 t or less per 1 t of the sheet-like waste in order to improve efficiency in the granulation process.

(Embodiment 5)
In the fourth embodiment, the cooling and cutting process of the second embodiment is preferably performed after the cleaning process and before the dehydration process in the fourth embodiment. The fluff produced through such cooling and cutting steps can be easily dehydrated and can be easily heated and melted during the granulation step, so that the processing efficiency can be further improved. And the vinyl chloride resin granulated product granulated by the granulation process has a dissolution rate in the solvent in the dissolution process as fast as a sheet or a fluff obtained by crushing it into small pieces, and the solution concentration is 20 weight. %, The processing efficiency can be remarkably improved.

  FIG. 7 is a diagram showing a flow of the present embodiment, which is the same as that of the first embodiment except that a cooling, a cutting process, a dehydration process, and a granulation process are provided after the cleaning process. The conditions to be performed are the same as those in the first to fourth embodiments.

(Embodiment 6)
In the first embodiment of the present invention, the vinyl chloride resin-containing solution is brought into contact with the vinyl chloride resin-containing solution in the recovery step to precipitate the vinyl chloride resin in the solution, and the precipitated vinyl chloride resin is separated. It is also a preferred form to use a method of recovering in this manner. In the first embodiment, the case of using a recovery process using hot water or the like has been described, but the vinyl chloride resin can also be recovered with high purity by such a recovery process.

  FIG. 8 is a diagram showing the flow of the present embodiment. In the recovery step, except that the vinyl chloride resin is precipitated using a non-solvent having a relatively low temperature, for example, room temperature, instead of hot water or the like. This is the same as the first embodiment. For this reason, the description of the same parts as those in the first embodiment is omitted, and the recovery process will be described below.

  In the recovery step of the present embodiment, water or a lower alcohol such as methanol, ethanol, propanol or the like can be used as a non-solvent that does not dissolve the vinyl chloride resin, and among these, handling is easy and cost is low. From the viewpoint of water, water is preferable. In this embodiment, as the solvent used for dissolving the vinyl chloride resin, the same solvent as in the other embodiments can be used.

  By supplying such a non-solvent into the vinyl chloride resin-containing solution from which the insoluble matter has been separated, the solubility of the vinyl chloride resin in the solvent decreases, and the bulk vinyl chloride resin can be deposited as a precipitate. . When it is desired to obtain a lumped vinyl chloride resin as small as possible, it is preferable to add the non-solvent with stirring. Moreover, it does not specifically limit as a temperature of the solution at the time of supplying a non-solvent, You may add at normal temperature.

  In the present embodiment, the vinyl chloride resin can be recovered by separating the precipitate and removing the residual solvent from the solution containing the bulk vinyl chloride resin, as in the first embodiment.

  As the recovery processing equipment used in the present embodiment, the same equipment as in the first embodiment can be used. However, since the solvent is not volatilized in the precipitation apparatus, the obtained vinyl chloride resin is recovered after solid-liquid separation. It is necessary to separately provide a device for evaporating and removing the solvent remaining in the vinyl chloride resin by heating the vinyl chloride resin. In that case, you may knead | mix and pelletize.

(Other embodiments)
Each of the embodiments described above is an example, and the embodiments not described in the above embodiments may be combined. In addition, the present invention can further employ the following steps.
(1) Magnetic processing step In the present invention, it is also a preferred embodiment to provide a magnetic processing step before the melting step. For example, it is possible to remove the metals from the sheet waste by performing a magnetic treatment step with a magnet or the like before the cleaning step.
(2) Vibrating screen process In the present invention, it is also a preferred embodiment to provide a vibrating screen process before the melting process. For example, the adhering material can be removed by vibrating the sheet-like waste with a vibrating screen before the cleaning process.
(3) Pre-cleaning step In the present invention, it is also a preferred embodiment that the sheet-like waste is pre-cleaned with water at room temperature before the cleaning step. For example, in order to remove soil substances having weak adhesion, it can be washed in advance with water at room temperature.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are merely examples and are not intended to limit the present invention, and any design changes based on the gist of the present invention will be described below. It is included in the technical scope.

  Agricultural vinyl sheet waste that has been cut into a size of about 100 mm square using the treatment process of the fifth embodiment and pre-treated to remove soil matter with weak adhesion in advance (adhesion amount of soil matter: disposal The vinyl chloride resin (degree of polymerization: 1,300) was recovered from about 0.055 t per 1 t of the product. The processing conditions for each step are as follows.

(Washing process)
The temperature of the washing water was changed to the temperatures shown in Table 1, respectively, and washing was performed while the residence time was 30 seconds, the inner tank rotation speed was 20 rpm, and water was supplied in an amount of 0.3 t / waste 1 t.

(Cooling, cutting process and dehydration process)
Each sheet-like waste heated in the washing process is cooled to room temperature, and a crusher is used to produce a 30 mm square fluff, which is dehydrated while supplying room-temperature water in an amount of 0.3 t / waste 1 t. Washing was performed, and further water was removed by centrifugal dehydration.

(Granulation process)
Next, the obtained fluff is supplied to a Henschel mixer, heated and melted to 130 to 140 ° C., stirred for 5 to 10 minutes, granulated, and then supplied to a cooler mixer to 50 to 60 ° C. in 2 minutes. While cooling, a vinyl chloride resin-containing granulated product (particle size: 3.0 mm, apparent specific gravity: 0.3 to 0.5 g / cm ³ ) was produced.

(Dissolution process)
The granulated product containing the vinyl chloride resin prepared above was put into a dissolution apparatus to prepare a slurry solution having a solution concentration of 20% by weight. Methyl ethyl ketone (boiling point: 79.6 ° C.) was used as the solvent, and dissolution was performed by heating and stirring the apparatus at 70 ° C. for 0.5 hours.

(Separation process)
While the solution was being pumped, insoluble matter was removed using a 100 μm nylon mesh filter.

(Recovery process)
The solution obtained from the separation step was continuously sent to the precipitation apparatus by a pump and charged into the precipitation apparatus. Steam (100 ° C.) was supplied into the solution while heating the solution to 50 to 60 ° C., and vinyl chloride resin was precipitated while evaporating methyl ethyl ketone. The resulting solution containing the particulate precipitate was further centrifuged to remove the residual solvent, and dried to recover the vinyl chloride resin.

  Table 1 shows the amount of deposit removal at each temperature in the cleaning process (based on the weight of the deposit included in the sheet waste before the cleaning process, and the reduction when compared with the weight of the deposit after the cleaning process) Ratio) and the amount of impurities contained in the recovered vinyl chloride resin. In this example, the amount of impurities is measured by dissolving the recovered vinyl chloride resin once in a solvent and further separating it by a centrifugal separation method.

  As shown in Table 1 above, it can be seen that a large amount of deposits have been removed from the sheet-like waste washed with warm water at 40 to 70 ° C., particularly 40 to 60 ° C. in the washing step. In addition, the vinyl chloride resin recovered by granulating the sheet-like waste, dissolving it, and precipitating it has a purity of 0.4% by weight or less of impurities that are weakly colored by soil. A high vinyl chloride resin is obtained.

  For reference, only pre-treatment is performed, and if the sheet-like waste from which the deposits have not been removed by the washing step is used for the dissolution step, the solution is heavily soiled, and the sheet-like waste is used in a solvent of 15% by weight or more. When added, sheet waste remained as a solid in the solution.

  As described above, the cleaning process of the present invention or the cooling process, the cutting process, the dehydration process and the granulation process together with the cleaning process of the present invention enables efficient treatment when recovering vinyl chloride resin from sheet-like waste by dissolution. And the amount of deposits can be greatly reduced. Therefore, if the present invention is used for recovery of vinyl chloride resin from sheet-like waste, it is possible to improve the processing efficiency and recover high purity vinyl chloride resin.

It is a flowchart which shows each process of Embodiment 1 of this invention. It is the schematic which shows an example of the washing | cleaning apparatus used for the washing | cleaning process of this invention. It is the schematic which shows one structural example of the melt | dissolution process of this invention, a isolation | separation process, and a collection | recovery process. It is a flowchart which shows each process of Embodiment 2 of this invention. It is a flowchart which shows each process of Embodiment 3 of this invention. It is a flowchart which shows each process of Embodiment 4 of this invention. It is a flowchart which shows each process of Embodiment 5 of this invention. It is a flowchart which shows each process of Embodiment 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cleaning apparatus 2 Dissolving apparatus 3 Separating apparatus 4 Deposition apparatus 21 41 Stirrer 22 42 Solution

Claims (7)

A method of recovering vinyl chloride resin from sheet-like waste containing vinyl chloride resin,
A washing step in which the sheet-like waste is put into a washing tank and water is supplied at a temperature of 40 to 70 ° C. for washing;
Dissolving the washed sheet waste in a solvent in which the vinyl chloride resin can be dissolved to obtain a vinyl chloride resin-containing solution; and
A separation step of separating insoluble matter from the vinyl chloride resin-containing solution;
A recovery step of recovering the vinyl chloride resin from the solution from which the insoluble matter has been removed;
A method for recovering a vinyl chloride resin.   The method for recovering a vinyl chloride resin according to claim 1, further comprising a step of cooling and cutting the washed sheet-like waste after the washing step and before the dissolving step.   2. The method according to claim 1, further comprising a granulation step after the washing step and before the dissolution step, after the washed sheet-like waste is heated and melted, and granulated to obtain a vinyl chloride resin-containing granulated product. Collection method of vinyl chloride resin.   The method for recovering a vinyl chloride resin according to claim 3, further comprising a dehydration step after the washing step and before the granulation step.   The recovery of the vinyl chloride resin according to any one of claims 1 to 4, wherein the recovery step includes a step of bringing a solution from which the insoluble matter has been removed into contact with hot water and / or steam to precipitate a vinyl chloride resin. Method.   The vinyl chloride system according to any one of claims 1 to 4, wherein the recovery step includes a step of adding a non-solvent of a vinyl chloride resin to the solution from which the insoluble matter has been removed to precipitate a vinyl chloride resin. Resin recovery method.   A vinyl chloride resin recovery treatment facility comprising the vinyl chloride resin recovery method according to any one of claims 1 to 6.

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