JP6331871B2 - Polymer dehydration method - Google Patents

Description

  The present invention relates to a method for dehydrating a polymer.

  As a method for producing rubber such as nitrile rubber, a method of polymerizing a monomer mixture, coagulating the obtained polymer, and further dehydrating is used. Specifically, the monomer mixture is polymerized by an emulsion polymerization method or a solution polymerization method, and the resulting polymer is solidified to form a crumb-like polymer. Here, the crumb-like polymer is a polymer containing water, and rubber is produced by dehydrating it.

  Patent Document 1 describes a method of dehydrating a polymer using a twin screw extruder. In Patent Document 1, a twin-screw extruder provided with a drain port and a polymer recovery port on the downstream side of a polymer aqueous solution supply port is used. Patent Document 2 describes a twin screw extruder in which a drain port and a polymer recovery port are provided on the downstream side of the polymer aqueous solution supply port, and a gas vent port is provided on the upstream side of the supply port. .

JP-A-1-202406 JP-A-8-108430

  However, in the configuration of the twin-screw extruder described in Patent Documents 1 and 2, it is difficult to sufficiently reduce the moisture contained in the polymer recovered at the recovery port and to improve the recovery rate of the polymer. there were.

  An object of the present invention is to provide a method for dehydrating a polymer that can sufficiently reduce moisture contained in the polymer to be recovered and can improve the recovery rate of the polymer.

  As a result of diligent research to solve the above-mentioned problems, the present inventors have found that excessive water is present in the supply port, resulting in poor polymer biting and poor polymerization recovery rate. The inventors have found that the above object can be achieved by providing a drain outlet upstream of the polymer supply inlet, and have completed the present invention.

That is, according to the present invention,
(1) A method of dewatering a polymer containing water using an extruder in which a screw is rotatably disposed inside a barrel, wherein at least the polymer containing water is supplied to the extruder. A polymer dehydrating method comprising: a supply port to be collected; a recovery port for recovering a polymer dehydrated downstream from the supply port; and an upstream drain port upstream from the supply port;
(2) The method for dehydrating a polymer according to (1), wherein the extruder further includes a downstream drainage port between the supply port and the recovery port,
(3) In the extruder, the polymer dehydration method according to (1) or (2), wherein the polymer containing water is pumped to the supply port by a transfer unit from a pipe connected to the supply port. Provided.

  According to the polymer dehydration method of the present invention, moisture contained in the recovered polymer can be sufficiently reduced, and the recovery rate of the polymer can be improved.

It is the schematic which shows the extruder used for the dehydration method of the polymer which concerns on embodiment. It is the schematic which shows the screw arrange | positioned inside the extruder which concerns on embodiment. It is the figure which showed the area | region corresponding to a supply zone among the screws which concern on embodiment. It is the figure which showed a part of screw of a forward flight.

  Hereinafter, the polymer dehydration method of the present invention will be described with reference to the drawings. The polymer dehydration method of the present invention is a method of dehydrating a polymer containing water using an extruder in which a screw is rotatably disposed inside a barrel, wherein the extruder includes at least water. A supply port to which a polymer containing is supplied, a recovery port for recovering the polymer dehydrated downstream from the supply port, and an upstream drain port upstream from the supply port.

  FIG. 1 is a schematic view showing an extruder used for dehydration of a polymer. The extruder 2 is a twin-screw extruder having a pair of screws 6 (see FIG. 2) inside the barrel 4. As shown in FIG. 1, the barrel 4 includes a drive unit 8 and 18 divided barrel blocks 11 to 28. In the barrel 4, an upstream dewatering zone 30, a supply zone 32, a downstream dewatering zone 34, and a drying zone 36 are sequentially formed from the upstream side to the downstream side of the barrel 4.

  In the present embodiment, the inside of the barrel blocks 11 to 13 corresponds to the upstream dewatering zone 30, the inside of the barrel blocks 14 and 15 corresponds to the supply zone 32, and the inside of the barrel blocks 16 to 20 is the downstream dewatering zone. 34 and the inside of the barrel blocks 21 to 28 corresponds to the drying zone 36. The number of barrel blocks installed in each zone can be implemented as an optimum number according to the type of polymer to be handled, physical properties, throughput, etc., and is not limited to the mode of the present embodiment.

  The barrel block 12 constituting the upstream dewatering zone 30 is formed with a rear drain slit 38 for discharging water contained in the polymer. Further, the barrel block 14 constituting the supply zone 32 is formed with a feed port 40 for receiving a polymer containing water. That is, the rear drain slit 38 is provided upstream of the feed port 40. In addition, the direction of the opening of the rear drain slit 38 is preferably horizontal or downward. Further, when the opening of the rear drain slit 38 is provided upward from the horizontal, water accumulates in the feed port 40, making it difficult for the water-containing crumb to bite into the screw, which may reduce the polymerization recovery rate.

  Further, it is preferable that a pipe 54 for supplying a polymer (slurry) containing water is directly connected to the feed port 40. A pressure pump 56 is connected to the pipe 54, and (slurry) stored in the tank 58 is pressurized by the pressure pump 56. Therefore, the slurry can be pumped through the pipe 54. Although the slurry may be supplied from the feed port 40 using a hopper, the number of rotations of the screw 6 can be reduced by feeding the slurry with the configuration shown in FIG. Temperature rise can be prevented.

  Further, the barrel blocks 17 and 20 constituting the downstream dewatering zone 34 are respectively formed with a first drain slit 42 and a second drain slit 44 for draining water contained in the polymer. Here, the first drain slit 42 and the second drain slit 44 are provided between a die 10 and a feed port 40 which will be described later.

  Vent ports 46, 48, 50 and 52 for deaeration are formed in the barrel blocks 22, 24, 26 and 28 constituting a part of the drying zone 36, respectively. Here, the first drain slit 42 and the second drain slit 44 are preferably provided from the viewpoint of draining efficiently, with the opening of the drain slit being provided horizontally or downward from the horizontal. Further, the vent ports 46, 48, 50, 52 are preferably provided such that the openings of the vent ports are provided upward from the horizontal.

  In the present embodiment, the die 10 for extruding the polymer dehydrated and dried in the barrel 4 into a predetermined shape and connected to the downstream side of the barrel block 28 is connected to the die 10. That is, the die 10 is provided downstream from the feed port 40.

  A cutting mechanism (not shown) is attached to the die 10, and a strand-like or sheet-like polymer extruded from the die 10 is recovered into a predetermined pellet or sheet by cutting into a suitable size. be able to. As the cutting mechanism, a mechanism such as immediately cutting the extruded strand or sheet with a hot cut device or cooling with a cooling tank and cutting with a cutter may be employed.

  Inside the barrel 4, a pair of screws 6 having the shape shown in FIG. Driving means such as a motor housed in a driving unit 8 (see FIG. 1) is connected to the base ends of the pair of screws 6 so that the pair of screws 6 rotate. It is held freely.

  In this embodiment, as shown in FIG. 2, when the length of the entire screw 6 is L (mm) and the outer diameter of the screw 6 is Da (mm), L / Da is preferably 30. It is -100, More preferably, it is 40-80. The outer diameter Da of the screw 6 is defined by the diameter of the angular flight peak portion 60 </ b> A (see FIG. 3) constituting the screw 6 when viewed from the axial direction. Moreover, when the axial length of the region corresponding to the supply zone 32 in the screw 6 is L1 (mm), the relationship between L1 and the overall length of the screw 6 described above is L (mm). , L1 / L, preferably 0.05 to 1.0, more preferably 0.05 to 0.8, and still more preferably 0.1 to 0.5.

  In the present embodiment, the screw 6 has an angular flight shape as shown in FIG. 3 at least in a region corresponding to the supply zone 32, that is, substantially perpendicular to the shaft center on the outer periphery of the screw shaft core. It is preferable that a flight is formed by spirally winding a square bar having a rectangular cross section. If the flight shape of the region corresponding to the supply zone 32 is a square flight shape, the space volume between the screw 6 and the inner wall of the barrel 4 is sufficiently large as compared to the case where the forward flight screw 6a as shown in FIG. Therefore, the penetration property of the polymer containing water into the screw 6 can be made sufficient. Moreover, since the polymer containing water becomes easy to bite into the screw 6, the recovery rate of the polymer can be increased.

  Further, the height of the peak portion 60A with respect to the axial center in the angular flight formed in the region corresponding to the supply zone 32 of the screw 6 is not particularly limited, but the biting property of the polymer containing water into the screw 6 is improved. From the point that it can be made favorable, it is preferable to be in the following range depending on the type of the polymer containing water. That is, the ratio of the valley 60B to the height of the axis (the height of the peak 60A relative to the axis / the height of the valley 60B relative to the axis) is preferably 1.1 to 5.0, more preferably 1. .1 to 4.5, more preferably 1.2 to 3.0.

  Furthermore, the width (thickness) of the peak portion 60A in the angular flight formed in the region corresponding to the supply zone 32 of the screw 6 is not particularly limited, but is preferably 0.1 to 10 mm, more preferably 0.5 to 0.5 mm. 5 mm.

  Alternatively, the interval between the crests 60A in the axial direction of the screw 6 in the angular flight formed in the region corresponding to the supply zone 32 of the screw 6 is not particularly limited, but the width (thickness) of the crest 60A of the angular flight. And the ratio of the valley 60B where the corner flight is not formed (that is, the portion between the peak portions 60A and 60A of the adjacent corner flight) (the width of the peak portion 60A / the width of the valley portion 60B), Preferably it is 0.01-1, More preferably, it is 0.02-0.5, More preferably, it is 0.02-0.2.

  In the region corresponding to the supply zone 32, the angle of the spiral of the angular flight formed on the screw 6 (that is, the angle at which the angular flight rises from the screw 6) is preferably 50 to 90 °, more preferably 55. It is -85 degrees, More preferably, it is 60-80 degrees.

  In the present embodiment, in the region corresponding to the supply zone 32, at least one of the above-described height, width, interval, and angle of the angular flight formed on the screw 6 is made of the polymer containing water. The extrudability of the polymer containing water by the screw 6 can be improved by adjusting appropriately so as to be within the above range according to the type, physical properties, processing amount and the like.

  In the present embodiment, the flight shape of the screw 6 in the region corresponding to the upstream dewatering zone 30, the downstream dewatering zone 34, and the drying zone 36 is not particularly limited, and the water-containing polymer is dewatered and dried. The flight shape may be a flight shape such as a half-angle flight or a forward flight (see FIG. 4), for example, because a polymer containing water can be sheared to generate heat appropriately. be able to.

  Alternatively, the screw 6 includes a plurality of kneading discs having a cross-sectional shape such as a pseudo ellipse, an oval shape, or a truncated triangle in a region corresponding to the upstream dewatering zone 30, the downstream dewatering zone 34, and the drying zone 36. A thing may be used.

Next, a method for dehydrating a polymer containing water using the extruder 2 shown in FIG. 1 will be described.
First, a slurry containing a water-containing polymer obtained as described above is prepared. In the present embodiment, it is preferable to adjust the solid content concentration of the slurry before dehydration by the extruder 2. The slurry whose solid content concentration is adjusted is stored in the tank 58.

  For example, a slurry containing a polymer obtained by using an emulsion polymerization method, that is, an agglomeration of a water-containing polymer formed by adding a coagulant to a latex of a polymer obtained by an emulsion polymerization method. Since the slurry containing the product (hydrous crumb) usually has a relatively high solid content of 15% by weight or more, the solid content can be adjusted to 5 to 10% by weight before dehydration by the extruder 2. preferable. In particular, since the slurry containing water-containing crumb has a relatively high solid content as described above, the water-containing crumbs are liable to adhere to each other. The bite property of the water-containing crumb by the screw 6 may be reduced. Therefore, before performing dehydration by the extruder 2, it is preferable to add water to the slurry containing the hydrous crumb in advance and thereby adjust the solid content concentration of the slurry containing the hydrous crumb to 5 to 10% by weight.

  In addition, when adjusting the solid content concentration of the slurry containing the hydrous crumb, the solid content concentration of the slurry containing the hydrous crumb is preferably 5 to 10% by weight as described above, more preferably 5 to 5% by weight. It is preferably 9% by weight, particularly 5-8% by weight. When the solid content concentration of the slurry containing the hydrous crumb is too low, the amount of water discharged from the slurry containing the hydrous crumb increases when the hydrous crumb is dehydrated by the extruder 2. There is a risk that the drainage will not catch up.

  In the present embodiment, the slurry containing the water-containing crumb stored in the tank 58 is introduced into the supply zone 32 from the feed port 40. Here, by pressurizing the slurry using the pressurizing pump 56, the slurry is pumped to the feed port 40 through the pipe 54. The hydrated crumb contained in the slurry introduced into the supply zone 32 is extruded to the downstream side of the supply zone 32 by the rotation of the screw 6. The temperature inside the supply zone 32 is preferably 30 to 100 ° C., more preferably 40 to 100 ° C. from the viewpoint that the viscosity of the polymer becomes appropriate and the extrudability of the hydrous crumb is improved.

  It is to be noted that the water-containing crumb contained in the slurry introduced from the feed port 40 is extruded to the downstream side of the supply zone 32 by the rotation of the screw 6, and the rear drain slit 38 provided in the barrel block 12. The water in the slurry and the water contained in the hydrated crumb are drained. Here, the drainage rate from the rear drain slit 38 is preferably 10 kg / hr or more, more preferably 30 kg / hr or more, further preferably 50 kg / hr, particularly preferably 80 kg / hr or more, and usually 400 kg / hr or less. is there. The temperature inside the upstream dewatering zone 30 is preferably 30 to 100 ° C, more preferably 40 to 100 ° C. The polymer dehydrated in the upstream dewatering zone 30 is pushed out downstream of the supply zone 32 and the like as the screw 6 rotates.

  The polymer introduced into the supply zone 32 is sent to the downstream dewatering zone 34 by the rotation of the screw 6. In the downstream dewatering zone 34, the water contained in the polymer is drained from the first drain slit 42 and the second drain slit 44 provided in the barrel blocks 17 and 20. The temperature inside the downstream dewatering zone 34 is preferably 50 to 120 ° C, more preferably 80 to 100 ° C.

  The polymer dehydrated in the downstream dewatering zone 34 is sent to the drying zone 36 by the rotation of the screw 6. The polymer sent to the drying zone 36 is plasticized and kneaded by the rotation of the screw 6 to become a melt, and is heated and heated to the downstream side. When this melt reaches the vent ports 46, 48, 50, 52 provided in the barrel blocks 22, 24, 26, 28, the pressure is released, so that the water contained in the melt is separated and vaporized. Is done.

  The separated and vaporized moisture (steam) is discharged to the outside through a vent pipe (not shown). The temperature inside the drying zone 36 is preferably 90 to 200 ° C, more preferably 100 to 160 ° C. The internal pressure is about 1000 to 5000 kPa.

The crumb from which moisture has been separated after passing through the drying zone 36 is sent to the outlet side by the screw 6 and is introduced into the die 10 in a state that substantially does not contain moisture (moisture content is 1% by weight or less). Here, for example, after being discharged in the form of a strand, it is introduced into a pelletizer (not shown), cut, made into an appropriate length and made into a product (pellet).

  According to the present embodiment, it is possible to sufficiently reduce the moisture contained in the polymer to be recovered, and to improve the polymer recovery rate. That is, by providing the rear drain slit 38 on the upstream side with respect to the feed port 40, drainage can be performed efficiently, and the polymer can be dehydrated while improving the polymerization recovery rate. Moreover, since the slurry supplied from the feed port 40 is pumped, the number of rotations of the screw can be reduced. Therefore, since the shearing applied to the polymer can be reduced and an excessive temperature rise can be prevented, deterioration of the polymer as a product to be obtained can be prevented. Furthermore, the recovery rate can be improved without increasing the screw rotation speed.

  The screw rotation speed is appropriately set in consideration of the polymer recovery rate and the polymer temperature, but is preferably 100 rpm or more, more preferably 130 rpm or more, still more preferably 150 rpm or more, preferably 400 rpm. Hereinafter, it is more preferably 300 rpm or less, still more preferably 250 rpm or less.

  The polymer recovery rate is preferably 25 kg / h or more, more preferably 30 kg / h or more, still more preferably 35 kg / h or more, and particularly preferably 40 kg / h or more.

(Polymer)
In the present embodiment, the type of polymer containing water to be dehydrated is not particularly limited. Examples of the polymer include styrene-butadiene copolymer (SBR), cementitious rubber such as nitrile rubber, acrylic resin, polyacetal resin, and vinyl chloride resin. Among these, the present invention can be suitably used for nitrile rubber.

(Nitrile rubber)
Although it does not specifically limit as nitrile rubber, For example, (alpha), (beta) -ethylenically unsaturated nitrile monomer, conjugated diene monomer, and other monomers copolymerizable with these used as needed The copolymer obtained by copolymerizing is mentioned.

  The α, β-ethylenically unsaturated nitrile monomer is not limited as long as it is an α, β-ethylenically unsaturated compound having a nitrile group, and α- such as acrylonitrile; α-chloroacrylonitrile, α-bromoacrylonitrile, etc. Halogenoacrylonitrile; α-alkylacrylonitrile such as methacrylonitrile; and the like, and acrylonitrile and methacrylonitrile are preferable. The α, β-ethylenically unsaturated nitrile monomer may be used alone, or a plurality of these may be used in combination.

  The content ratio of the α, β-ethylenically unsaturated nitrile monomer unit in the nitrile rubber used in the present invention is preferably 10 to 60% by weight, more preferably 15% in 100% by weight of all monomer units. An amount of -55% by weight, particularly preferably 20-50% by weight. If the content of the α, β-ethylenically unsaturated nitrile monomer unit is too small, the oil resistance of the resulting rubber cross-linked product may be reduced. Conversely, if it is too much, cold resistance may be reduced. .

  As the conjugated diene monomer, a conjugated diene monomer having 4 to 6 carbon atoms such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, chloroprene is preferable. 1,3-butadiene and isoprene are more preferred, and 1,3-butadiene is particularly preferred. Of these, 1,3-butadiene is preferred. These may be used alone or in combination of two or more.

  The content ratio of the conjugated diene monomer unit in the nitrile rubber is preferably 40 to 90% by weight, more preferably 45 to 85% by weight, particularly preferably 50 to 80% in 100% by weight of the total monomer units. % By weight. If the content of the conjugated diene monomer unit is too low, the elasticity of the resulting rubber cross-linked product may be reduced. If it is too high, the rubber cross-linked product will have oil resistance, heat aging resistance, chemical stability, etc. It can be damaged.

  The nitrile rubber used in the present invention may be a copolymer of an α, β-ethylenically unsaturated nitrile monomer and a conjugated diene monomer and another copolymerizable monomer. Good. Such other monomers include ethylene, α-olefin monomer, α, β-ethylenically unsaturated carboxylic acid ester monomer, α, β-ethylenically unsaturated carboxylic acid monomer, α , Β-ethylenically unsaturated polyvalent carboxylic acid anhydride monomer, aromatic vinyl monomer, fluorine-containing vinyl monomer, copolymerizable anti-aging agent, etc., and α, β-ethylenically unsaturated Carboxylic acid ester monomers are preferably used.

  Examples of the α, β-ethylenically unsaturated carboxylic acid monomer include α, β-ethylenically unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; α, β such as maleic acid, fumaric acid, and itaconic acid. -Ethylenically unsaturated polyvalent carboxylic acid; maleic acid monoalkyl ester such as monomethyl maleate, monoethyl maleate, monopropyl maleate, mono n-butyl maleate, monocyclopentyl maleate, monocyclohexyl maleate, mono maleate Maleic acid monocycloalkyl esters, such as cycloheptyl, maleic acid monomethylcyclopentyl, maleic acid monoalkylcycloalkyl esters, such as monoethylcyclohexyl maleate, monomethyl fumarate, monoethyl fumarate, monopropyl fumarate, mono n-butyl fumarate Fumaric acid monoalkyl esters such as fumaric acid monocyclopentyl, fumaric acid monocyclohexyl, fumaric acid monocycloalkyl esters such as monocycloheptyl fumarate, monomethylcyclopentyl fumarate, monoalkylcyclohexyl fumarate such as monoethylcyclohexyl fumarate, etc. Citraconic acid monoalkyl esters such as alkyl esters, monomethyl citraconic acid, monoethyl citraconic acid, monopropyl citraconic acid, mono n-butyl citraconic acid, citraconic acid monocyclopentyl, citraconic acid monocyclohexyl, citraconic acid monocycloheptyl Citraconate monoalkyl citrates such as cycloalkyl esters, monomethylcyclopentyl citraconic acid, and monoethylcyclohexyl citraconic acid. Itaconic acid, such as cycloalkyl ester, itaconic acid monomethyl, itaconic acid monoethyl, itaconic acid monopropyl, itaconic acid mono-n-butyl, itaconic acid monoalkylpenta, itaconic acid monocyclopentyl, itaconic acid monocycloheptyl And α, β-ethylenically unsaturated polyvalent carboxylic acid partial esters such as monocycloalkyl esters, itaconic acid monomethylcyclopentyl, itaconic acid monoalkyl cyclohexyl esters, and the like.

  These other copolymerizable monomers may be used alone or in combination. The content of these other monomer units in the nitrile rubber used in the present invention is preferably 30% by weight or less, more preferably 15% by weight or less, particularly preferably 100% by weight of the total monomer units. Is less than 5% by weight.

  The Mooney viscosity [ML1 + 4 (100 ° C.)] of the nitrile rubber used in the present invention is preferably 5 to 200, more preferably 10 to 100, and further preferably 30 to 80. The Mooney viscosity of the nitrile rubber can be adjusted by appropriately selecting conditions such as the amount of the chain transfer agent, the polymerization reaction temperature, and the polymerization initiator concentration.

  The method for producing the nitrile rubber is not particularly limited. For example, the α, β-ethylenically unsaturated nitrile monomer, the conjugated diene monomer, and other units copolymerizable with these added as necessary. A method of copolymerizing the monomer is convenient and preferred. As the polymerization method, any of the known emulsion polymerization method and solution polymerization method can be used, but the emulsion polymerization method is preferable because the polymerization reaction can be easily controlled. According to the emulsion polymerization method, the nitrile rubber can be obtained in the form of a latex in which the nitrile rubber is dispersed in an aqueous medium. According to the solution polymerization method, the nitrile rubber can be obtained in an organic solvent. Can be obtained in the form of a cement formed by dissolution.

  And in this embodiment, you may hydrogenate at least one part among the carbon-carbon double bonds in the polymer principal chain of a nitrile rubber as needed. The type and amount of the hydrogenation catalyst used in the hydrogenation reaction, the hydrogenation temperature, etc. may be determined according to known methods. When hydrogenating nitrile rubber, hydrogenation may be performed so that the iodine value of the resulting hydrogenated nitrile rubber is preferably 120 or less, more preferably 80 or less, and even more preferably 50 or less. Good.

(Polymer containing water)
Next, the water-containing polymer used in the present invention will be described taking nitrile rubber as an example.
The method for producing the polymer containing water is not particularly limited. For example, when the nitrile rubber is produced by the above-described emulsion polymerization method, it is coagulated on the nitrile rubber latex obtained by the emulsion polymerization method. By adding an agent to solidify the nitrile rubber, a crumb-like nitrile rubber containing water (hydrous crumb) can be obtained.

  The coagulant for coagulating latex nitrile rubber is not particularly limited. For example, inorganic acids such as sulfuric acid and hydrochloric acid; organic acids such as acetic acid; calcium chloride, magnesium chloride, sodium chloride, magnesium sulfate, and aluminum sulfate. Inorganic salts such as barium chloride; and mixtures thereof may be used, and may be determined as appropriate depending on the type of emulsifier used in the nitrile rubber latex. Among these, inorganic salts are preferable, and sodium chloride which is a monovalent inorganic salt is more preferable.

  Alternatively, when the nitrile rubber is produced by the solution polymerization method described above, by adding a coagulating liquid such as water to the cementitious nitrile rubber obtained by the solution polymerization method, the nitrile rubber is precipitated. A crumb-like nitrile rubber (water-containing crumb) containing water can be obtained.

  For example, water is used as a coagulating liquid for coagulating the nitrile rubber of cement. The amount of the coagulating liquid is not particularly limited, but is (1: 0.05) to (1) in a volume ratio of (nitrile rubber solvent: coagulating liquid) to cementitious nitrile rubber solvent (for example, acetone). : 3) is preferable. By setting the amount of the coagulating liquid within the above range, the solidification of the nitrile rubber can be sufficiently advanced, the uncoagulated content can be reduced, and the yield can be improved.

  In the present embodiment, it is preferable to perform filtration and washing with respect to the polymer containing water obtained as described above in order to remove the coagulant contained in the polymer.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples. In the following, “part” is based on weight unless otherwise specified. The physical properties were measured as follows.

(Residual water content)
The residual water content of the polymer was measured from the loss on heating when the polymer was dried in an oven at 105 ° C. for 1 hour.

Example 1
In a metal bottle, 225 parts of ion-exchanged water, 25 parts of an aqueous sodium dodecylbenzenesulfonate solution having a concentration of 10% by weight, 37 parts of acrylonitrile, mono-n fumarate? 4 parts butyl, t? After 0.5 parts of dodecyl mercaptan (molecular weight modifier) was charged in this order, the internal gas was replaced with nitrogen three times, and then 59 parts of butadiene was charged. Next, the metal bottle was kept at 5 ° C., 0.1 part of cumene hydroperoxide (polymerization initiator) was charged, and the polymerization reaction was carried out for 16 hours while rotating the metal bottle. And after adding 0.1 part of hydroquinone aqueous solution (polymerization terminator) with a concentration of 10% by weight to stop the polymerization reaction, the residual monomer was removed using a rotary evaporator at a water temperature of 60 ° C., and the acrylonitrile monomer was removed. A carboxyl group-containing nitrile rubber latex (solid content concentration: 30% by weight) having 34% by weight unit, 62.5% by weight butadiene monomer unit and 3.5% by weight mono-n-butyl fumarate monomer unit is obtained. It was.

  Then, a palladium catalyst solution (1 wt% palladium acetate / acetone solution, equal weight ions) was added to the autoclave so that the palladium content was 1,000 ppm by weight with respect to the dry rubber weight contained in the obtained latex. A solution in which exchanged water is mixed), a hydrogenation reaction is carried out for 6 hours at a hydrogen pressure of 3 MPa and a temperature of 50 ° C., and then the solid content concentration is adjusted with ion-exchanged water to obtain a carboxyl group-containing highly saturated nitrile rubber latex (Solid content concentration 13 wt%) was obtained.

  Next, 100 parts of the carboxyl group-containing highly saturated nitrile rubber latex (in terms of solid content) is added to and mixed with 80 parts of a sodium chloride aqueous solution having a concentration of 6.5% by weight (in terms of solid content) with stirring. Thus, a solidified crumb was obtained. In addition, when adding and mixing with the said stirring, this liquid mixture was adjusted to pH = 4 by adding a sulfuric acid to the liquid mixture obtained. Subsequently, the obtained solidified crumb was taken out, filtered and washed with water, and then water was added to obtain a hydrated crumb slurry of carboxyl group-containing highly saturated nitrile rubber having a concentration of 7.6% by weight.

  Then, using the water-containing crumb of the obtained carboxyl group-containing highly saturated nitrile rubber, the water-containing crumb was dehydrated using the extruder 2 having the configuration shown in FIGS. In addition, the extrusion apparatus was rearranged so that it might become the structure of FIG.

  In the present embodiment, as the extruder 2, a twin-screw extruder in which two screws 6 and 6 are provided in parallel in the barrel 4 and these screws 6 and 6 are meshed and rotated in the same direction was used.

  As for the screw 6, the flight shape in the region corresponding to the supply zone 32 is the angular flight shown in FIG. 3, and the flight shape in the region corresponding to the upstream dewatering zone 30, the downstream dewatering zone 34 and the drying zone 36. However, the screw which is a forward flight shown in FIG. 4 was used. In addition, regarding the angular flight of the screw 6, the ratio (height with respect to the axis of the crest 60A / height with respect to the axis of the trough 60B) described above is 1.6, and the width (thickness) of the crest 60A is 2. 0.5 mm (the width of the crest 60A / the width of the trough 60B) is 0.06, and the angle at which the angular flight rises from the screw 6 is 65 °.

  The upstream dewatering zone 30 upstream of the supply zone 32 is the same as that used in the downstream dewatering zone 34, and has a barrel block 12 having openings on both sides that are transverse to the flow direction as rear drain slits 38. Was used.

  And the piping 54 of the hydrated crumb slurry of the obtained carboxyl group containing highly saturated nitrile rubber was connected to the feed port 40 of the extruder 2 of such a structure, and it supplied at a rate of 579 kg / hr. In this example, the internal temperature of the supply zone 32 was set to 60 ° C., the internal temperature of the downstream dewatering zone 34 was set to 90 ° C., and the internal temperature of the drying zone 36 was set to 110 ° C. The internal temperature of the upstream dewatering zone 30 was set to 60 ° C.

  As a result, the sheet-like dried carboxyl group-containing highly saturated nitrile rubber was recovered from the die 10 connected to the downstream side of the barrel at a recovery rate of 44 kg / hr. In addition, about the motor of the extruder 2, as shown in Table 1, the rotation speed was 197 rpm. In the drying zone 36, heat was generated by shearing the hydrated crumb, and the temperature (drying temperature) in the drying zone 36 was 148 ° C.

  In this example, no hydrated crumb stayed at the feed port 40 of the extruder 2. Further, the residual water content of the water contained in the recovered carboxyl group-containing highly saturated nitrile rubber was 0.8%, and the water-containing crumb was successfully dehydrated. The results are shown in Table 1.

(Example 2)
The water-containing crumb was dehydrated in the same manner as in Example 1 except that the concentration of the water-containing crumb slurry of the carboxyl group-containing highly saturated nitrile rubber supplied from the feed port 40 was changed to 5.8% by weight. The recovery rate of the sheet-like dried carboxyl group-containing highly saturated nitrile rubber was recovered at a recovery rate of 40 kg / hr. The residual moisture content of the moisture contained in the recovered carboxyl group-containing highly saturated nitrile rubber was 0.6%.

(Example 3)
The concentration of the hydrated crumb slurry of carboxyl group-containing highly saturated nitrile rubber supplied from the feed port 40 is changed to 6% by weight, and instead of the configuration in which the pipe 54 is connected to the feed port 40 of the extruder 2, a hopper is used. The water-containing crumb slurry was dehydrated in the same manner as in Example 1 except that the water-containing crumb slurry of the carboxyl group-containing highly saturated nitrile rubber was supplied from the feed port 40 and the motor speed of the extruder 2 was changed to 280 rpm. It was. The recovery rate of the sheet-like dried carboxyl group-containing highly saturated nitrile rubber was recovered at a recovery rate of 32 kg / hr. The residual water content of the water contained in the recovered carboxyl group-containing highly saturated nitrile rubber was 0.1%.

(Comparative Example 1)
The concentration of the hydrated crumb slurry of the carboxyl group-containing highly saturated nitrile rubber supplied from the feed port 40 is changed to 6% by weight, the rear drain slit 38 is not provided, and the gap between the second drain slit 44 and the die 10 is changed. A feed drain 40 is used to supply a hydrated crumb slurry of carboxyl group-containing highly saturated nitrile rubber via a hopper instead of a configuration having a third drain slit (not shown) and connecting the pipe 54 to the feed port 40. The water-containing crumb was dehydrated in the same manner as in Example 1 except that the extruder 2 having the configuration described above was used, and the rotation speed of the motor of the extruder 2 was changed to 146 rpm. The recovery rate of the sheet-like dried carboxyl group-containing highly saturated nitrile rubber was recovered at a recovery rate of 20 kg / hr. The residual moisture content of the moisture contained in the recovered carboxyl group-containing highly saturated nitrile rubber was 0.3%.

  As shown in Table 1, a method of dewatering a polymer containing water using an extruder in which a screw is rotatably disposed inside a barrel, the extruder including at least water Dehydration by a polymer dehydration method comprising a supply port to which a polymer is supplied, a recovery port for recovering a polymer dehydrated downstream from the supply port, and an upstream drain port upstream from the supply port Then, the residual moisture in the polymer was small, and the polymer recovery rate was good.

2 ... Extruder, 4 ... Barrel, 6 ... Screw, 10 ... Die, 30 ... Upstream dewatering zone, 32 ... Feeding zone, 34 ... Downstream dewatering zone, 36 ... Drying zone, 38 ... Rear drain slit, 40 ... Feed Mouth, 42 ... first drain slit, 44 ... second drain slit

Claims (3)

A method of dehydrating a polymer containing water using an extruder in which a screw is rotatably arranged inside a barrel,
The extruder has at least a supply port to which a polymer containing water is supplied,
A recovery port for recovering the polymer dehydrated downstream from the supply port;
A method for dehydrating a polymer , comprising an upstream drain port upstream from the supply port , wherein a flight shape in a region corresponding to the supply zone of the screw is a square flight shape .   The method for dehydrating a polymer according to claim 1, wherein the extruder further includes a downstream drainage port between the supply port and the recovery port. The method for dehydrating a polymer according to claim 1 or 2, wherein in the extruder, the polymer containing water is pressure-fed to the supply port by a transfer unit from a pipe connected to the supply port.

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