JP2015183029A - Method of dehydrating hydrous crumb - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of dehydrating hydrous crumb which causes hydrous crumb of a nitrile rubber to penetrate the screw in the extruder efficiently for extrusion during dehydrating hydrous crumb by using an extruder so as to improve the dehydration treatability of the hydrous crumb.SOLUTION: A dehydrating method of hydrous crumb comprises dehydrating a slurry containing hydrous crumb comprising a crumby nitrile rubber by using an extruder 1, in which a screw is arranged freely rotatably inside a barrel 3. The flight shape of the screw in regions 31 and 32 corresponding to a supply zone 100 for the hydrous crumb formed in the barrel 3 is an angular flight. The solid content concentration of the slurry is 5-10 wt.%, and the Mooney viscosity (ML, 100°C) of the nitrile rubber is 5-200.

Description

  The present invention relates to a method for dehydrating hydrous crumbs.

  Conventionally, as a method for producing rubber such as nitrile rubber, a water-containing crumb of rubber formed by polymerizing a monomer mixture by an emulsion polymerization method or a solution polymerization method and coagulating the obtained polymer is dehydrated. The method of manufacturing by doing is used.

Here, in the production of such a rubber, as a method of dehydrating the hydrous crumb, for example, in Patent Document 1, the hydrous crumb is kneaded with a screw using an extruder in which a screw is disposed in a barrel. A method for dehydration is disclosed.
However, in the dehydration method of the hydrous crumb disclosed in Patent Document 1, depending on the type of rubber to be dehydrated, the wettability of the hydrous crumb into the screw is not always sufficient, and the hydrous crumbs are attached to each other. Therefore, if the amount of the water-containing crumb introduced into the extruder is increased, the water-containing crumb stays, the feed port for supplying the water-containing crumb into the extruder is blocked, and the dewaterability of the water-containing crumb is reduced. There was a problem of being lowered.

JP-A-2005-97576

  The present invention has been made in view of such a situation, and when dehydrating a hydrous crumb containing crumb-like nitrile rubber using an extruder, it improves the biting property and extrudability of the hydrous crumb in the extruder. Accordingly, an object of the present invention is to provide a method for dewatering a hydrous crumb that can improve the dewaterability of the hydrous crumb.

  As a result of diligent research to solve the above problems, the present inventors, when dewatering the hydrous crumb using an extruder, the flight shape of the portion of the extruder screw corresponding to the supply zone of the extruder, The present inventors have found that the above object can be achieved by adopting a corner flight, and have completed the present invention.

  That is, according to the present invention, a water-containing crumb containing crumb-like nitrile rubber is dehydrated using an extruder in which a screw is rotatably disposed inside a barrel, and the extruder includes: There is provided a method for dewatering a hydrous crumb, wherein the flight shape of the screw in a region corresponding to a supply zone for supplying the hydrous crumb is an angular flight.

In this invention, after adjusting the solid content concentration of the slurry containing the said hydrous crumb to 5 to 10 weight%, it is preferable to supply the slurry containing the said hydrous crumb to the said extruder.
Moreover, in this invention, it is preferable that the Mooney viscosity (ML1 _{+ 4} , 100 degreeC) of the said nitrile rubber is 5-200.
Furthermore, in the present invention, it is preferable that a dewatering zone and a drying zone are sequentially provided on the downstream side of the supply zone of the extruder.

  According to the present invention, when dewatering the hydrous crumb using an extruder, the biting property in the feeding zone of the extruder and the extrudability of the hydrous crumb into the dewatering zone in the extruder are improved, thereby It is possible to provide a method for dewatering a hydrous crumb that can improve the dewaterability of the hydrated crumb.

FIG. 1 is a schematic view showing an extruder used in a method for dewatering a hydrous crumb according to an embodiment of the present invention. FIG. 2 is a schematic view showing a screw disposed inside the extruder of FIG. FIG. 3 is a view showing a region corresponding to the supply zone in the screw of FIG. FIG. 4 is a view showing a part of a forward flight screw according to a conventional example.

  The method for dehydrating a hydrous crumb of the present invention is a method for dehydrating a hydrous crumb containing crumb-like nitrile rubber using an extruder in which a screw is rotatably disposed inside a barrel, the extruder The flight shape of the screw in the region corresponding to the supply zone for supplying the hydrous crumb is a square flight.

Nitrile rubber First, the nitrile rubber used in the present invention will be described.
The nitrile rubber used in the present invention is not particularly limited. For example, α, β-ethylenically unsaturated nitrile monomer, conjugated diene monomer, and other copolymerizable with these used as necessary And a copolymer obtained by copolymerizing the above monomer.

  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 used in the present invention is preferably 40 to 90% by weight, more preferably 45 to 85% by weight, particularly preferably 100% by weight of all monomer units. Is an amount of 50 to 80% 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 and the like.

  The α-olefin monomer preferably has 3 to 12 carbon atoms, and examples thereof include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene.

  Examples of the α, β-ethylenically unsaturated carboxylic acid ester monomer include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, n-dodecyl acrylate, methyl methacrylate, and ethyl methacrylate. Acrylic acid alkyl esters and methacrylic acid alkyl esters having an alkyl group with 1 to 18 carbon atoms; acrylic acid alkoxyalkyl esters and methacrylic acid alkoxyalkyl esters such as methoxymethyl acrylate and methoxyethyl methacrylate; An alkoxyalkyl group having 2 to 12 carbon atoms; acrylic acid cyanoalkyl ester such as α-cyanoethyl acrylate, β-cyanoethyl acrylate, cyanobutyl methacrylate, and cyanoalkyl methacrylate A cyanoalkyl group having 2 to 12 carbon atoms; acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, and hydroxyalkyl methacrylates; A hydroxyalkyl group having 1 to 12 carbon atoms; fluorine-substituted benzyl group-containing acrylic ester such as fluorobenzyl acrylate and fluorobenzyl methacrylate; and fluorine-substituted benzyl group-containing methacrylate ester; trifluoroethyl acrylate Fluoroalkyl group-containing acrylic acid ester and fluoroalkyl group-containing methacrylate ester such as tetrafluoropropyl methacrylate; dimethyl maleate, dimethyl fumarate, dimethyl itaconate, And unsaturated polyvalent carboxylic acid polyalkyl esters such as diethyl taconate; amino group-containing α, β-ethylenically unsaturated carboxylic acid esters such as dimethylaminomethyl acrylate and diethylaminoethyl acrylate;

  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.

Examples of the α, β-ethylenically unsaturated polyvalent carboxylic acid anhydride monomer include maleic anhydride.
Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyl pyridine and the like.

  Examples of the fluorine-containing vinyl monomer include fluoroethyl vinyl ether, fluoropropyl vinyl ether, o-trifluoromethylstyrene, vinyl pentafluorobenzoate, difluoroethylene, and tetrafluoroethylene.

  Examples of copolymerizable anti-aging agents include N- (4-anilinophenyl) acrylamide, N- (4-anilinophenyl) methacrylamide, N- (4-anilinophenyl) cinnamamide, N- (4-anilino). Phenyl) crotonamide, N-phenyl-4- (3-vinylbenzyloxy) aniline, N-phenyl-4- (4-vinylbenzyloxy) aniline 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 [ML _{1 + 4} (100 ° C.)] of the nitrile rubber used in the present invention is preferably 5 to 200, more preferably 10 to 100, and still more 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 production method of the nitrile rubber used in the present invention is not particularly limited, and for example, α, β-ethylenically unsaturated nitrile monomer, conjugated diene monomer, and these can be copolymerized with these if necessary. A method of copolymerizing other monomers is convenient and preferable. 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.

Water-containing crumb Next, the water-containing crumb used in the present invention will be described.
The method for producing the hydrous crumb is not particularly limited. For example, when the nitrile rubber is produced by the emulsion polymerization method described above, a coagulant is added to the latex of the nitrile rubber obtained by the emulsion polymerization method. By solidifying 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 filter and wash the water-containing crumb obtained as described above in order to remove the coagulant contained in the water-containing crumb.

Method for Dehydrating Hydrous Clam Next, a method for dehydrating the hydrous crumb obtained as described above will be described.
FIG. 1 is a schematic view showing an extruder used in a method for dehydrating a hydrous crumb according to an embodiment of the present invention, FIG. 2 is a schematic view showing a screw arranged inside the extruder of FIG. 1, and FIG. FIG. 4 is a view showing a part of a forward flight screw according to a conventional example.

  Hereinafter, a single extruder 1 shown in FIG. 1 will be exemplified as a dewatering device for hydrous crumbs used in the present invention, and the configuration thereof will be described.

  An extruder 1 serving as a dewatering device for a hydrous crumb according to the present embodiment is a twin-screw extruder having a pair of screws inside a barrel 3. As shown in FIG. 1, the barrel 3 of the extruder 1 includes a drive unit 2 and 15 divided barrel blocks 31 to 45, and inside the barrel 3, a supply zone 100, a dewatering zone 102, The drying zone 104 is sequentially formed from the upstream side to the downstream side of the barrel 3.

  The supply zone 100 is an area for supplying the slurry containing the hydrous crumb into the barrel 3. The dehydration zone 102 is an area for separating and discharging a liquid (serum water) containing a coagulant and the like from a slurry containing water-containing crumb. The drying zone 104 is an area for drying the dewatered crumb.

  In the present embodiment, the inside of the barrel blocks 31 and 32 corresponds to the supply zone 100, the inside of the barrel blocks 33 to 37 corresponds to the dehydration zone 102, and the inside of the barrel blocks 38 to 45 corresponds to the drying zone 104. In addition, the number of installation of each barrel block can be implemented with the optimal number according to the water-containing crumb to handle, and is not limited to the aspect of this embodiment.

  A feed port 310 that receives the hydrous crumb is formed in the barrel block 31 constituting the supply zone 100. The barrel blocks 34 and 37 constituting the dewatering zone 102 are formed with discharge slits 340 and 370 for draining water contained in the water-containing crumb. Vent ports 390, 410, 430, and 450 for deaeration are formed in the barrel blocks 39, 41, 43, and 45 constituting a part of the drying zone 104, respectively.

  Inside the barrel 3, a pair of screws 5 having the shape shown in FIG. Drive means such as a motor stored in the drive unit 2 (see FIG. 1) are connected to the base ends of the pair of screws 5 so that the pair of screws 5 rotate. It is held freely.

  In the present embodiment, as shown in FIG. 2, when the length of the entire screw 5 is L (mm) and the outer diameter of the screw 5 is Da (mm), L / Da is preferably 30. It is -100, More preferably, it is 40-80. The outer diameter Da of the screw 5 is defined by the diameter of the angular flight peak portion 50A (see FIG. 3) constituting the screw when viewed from the axial direction. Moreover, when the axial length of the area | region corresponding to the supply zone 100 among the screws 5 is set to L1 (mm), the relationship between L1 and the above-mentioned total length of the screw 5 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 5 has an angular flight shape as shown in FIG. 3 at least in a region corresponding to the supply zone 100, that is, substantially perpendicular to the shaft center on the outer periphery of the screw shaft core. A flight is formed by spirally winding a square bar having a rectangular cross section so as to stand up.

  In this embodiment, about the screw 5 which comprises the extruder 1, the area | region corresponding to the supply zone 100 is made into a square flight, for example, the area | region corresponding to the supply zone 100 is made a forward flight as shown in FIG. Compared with the case where it forms with the screw 5a of this, a water-containing crumb can be processed efficiently.

  That is, when the region corresponding to the supply zone 100 is formed by the forward flight screw 5a as shown in FIG. 4, the forward flight screw 5a has a curved flight shape. The space between 5a and the space between the screw 5 and the inner wall of the barrel 3 are reduced, and the space volume in the barrel 3 in the region corresponding to the supply zone 100 is also reduced. The crumb hardly bites into the screw 5a, and the flight shape is curved, so that the extrudability of the hydrous crumb into the dehydration zone by the screw 5a may be lowered. In particular, when a rubber having a low bulk density such as a nitrile rubber is used, the bite into the screw 5a is often insufficient, and thus the extrudability may be significantly reduced.

  On the other hand, by making the flight shape of the region corresponding to the supply zone 100 of the pair of screws 5 constituting the extruder 1 into a square flight, the space between the screw 5 and the screw 5, The space between the inner wall of the barrel 3 can be increased, and as a result, the space volume in the barrel 3 in the region corresponding to the supply zone 100 is increased, so that the hydrous crumb can easily bite into the screw 5. Thus, the hydrous crumb can be efficiently extruded.

  Further, the height of the peak portion 50A with respect to the axial center in the angular flight formed in the region corresponding to the supply zone 100 of the screw 5 is not particularly limited, but the bite property of the hydrous crumb into the screw 5 is good. From the point that can be done, it is preferable to set the following range depending on the type of hydrous crumb. That is, the ratio of the valley 50B to the height of the axis (the height of the peak 50A with respect to the axis / the height of the valley 50B with respect 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 50A in the angular flight formed in the region corresponding to the supply zone 100 of the screw 5 is not particularly limited, but is preferably 0.1 to 10 mm, more preferably 0.5 to. 5 mm.

  Alternatively, the interval between the peak portions 50A in the axial direction of the screw 5 in the angular flight formed in the region corresponding to the supply zone 100 of the screw 5 is not particularly limited, but the width (thickness) of the peak portion 50A of the angular flight. And the ratio of the width of the valley portion 50B where the corner flight is not formed (that is, the portion between the peak portions 50A and 50A of the adjacent corner flight) (the width of the peak portion 50A / the width of the valley portion 50B), Preferably it is 0.01-1, More preferably, it is 0.02-0.5, More preferably, it is 0.02-0.2.

  Further, in the region corresponding to the supply zone 100, the angle of the spiral of the angular flight formed on the screw 5 (that is, the angle at which the angular flight rises from the screw 5) 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 100, at least one of the height, width, interval, and angle described above for the angular flight formed on the screw 5, the type of hydrated crumb, the physical properties, and the treatment The extrudability of the hydrous crumb by the screw 5 of the extruder 1 can be improved by appropriately adjusting the amount to be in the above range according to the amount and the like.

  In the present embodiment, the flight shape of the screw 5 in the region corresponding to the dehydration zone 102 and the drying zone 104 is not particularly limited, and may be a flight shape suitable for dehydration / drying of the hydrated crumb. From the point that the hydrous crumb can be sheared to generate heat appropriately, it is possible to obtain a flight shape such as a half-angle flight or a forward flight. Alternatively, the screw 5 may have a plurality of kneading disks having a cross-sectional shape such as a pseudo ellipse, an oval, or a truncated triangle in a region corresponding to the dewatering zone 102 or the drying zone 104.

  In the present embodiment, a die 4 is connected to the downstream side of the barrel block 45 described above for extruding nitrile rubber dehydrated and dried in the barrel 3 into a predetermined shape. A cutting mechanism (not shown) is attached to the die 4, and a strand-like or sheet-like polymer extruded from the die is cut into an appropriate size to obtain a predetermined pellet or sheet. 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.

Next, the water-containing crumb dehydration method using the extruder 1 according to this embodiment will be described.
First, a slurry containing hydrated crumbs of nitrile rubber obtained as described above is prepared. In the present embodiment, before the slurry containing the prepared hydrous crumb is dehydrated by the extruder 1, the solid content concentration of the slurry containing the hydrous crumb in which the hydrous crumb is dispersed in water is adjusted.

  For example, a slurry containing a hydrous crumb obtained by using the above-described emulsion polymerization method, that is, a nitrile rubber hydrous crumb formed by adding a coagulant to a nitrile rubber latex obtained by the emulsion polymerization method. Since the slurry usually has a relatively high solid content concentration of 15% by weight or more, it is preferable to adjust the solid content concentration to 5 to 10% by weight before dehydration by the extruder 1. In particular, since the slurry containing the hydrated crumb of nitrile rubber has a relatively high solid content concentration as described above, the hydrated crumbs are likely to adhere to each other. The bite property of the water-containing crumb by the screw 5 of the extruder 1 may be reduced. Therefore, before performing dehydration by the extruder 1, it is preferable to add water to the slurry containing the hydrated crumb in advance, thereby adjusting the solid content concentration of the slurry containing the hydrated 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 water-containing crumb is too low, the amount of water discharged from the slurry containing the water-containing crumb increases when the water-containing crumb is dehydrated by the extruder 1. There is a risk that the drainage will not catch up.

  In the present embodiment, the prepared slurry containing the hydrous crumb is introduced into the supply zone 100 from the feed port 310. The water-containing crumb contained in the slurry containing the water-containing crumb introduced into the supply zone 100 is extruded to the downstream side of the supply zone 100 by the rotation of the screw 5. The temperature inside the supply zone 100 is preferably 30 to 100 ° C, more preferably 40 to 100 ° C. By setting the temperature of the supply zone in the above range, the viscosity of the hydrous crumb becomes appropriate, and the extrudability of the hydrous crumb is improved.

  The hydrous crumb introduced into the supply zone 100 is sent to the dehydration zone 102 by the rotation of the screw 5. In the dehydration zone 102, water contained in the water-containing crumb is drained from the slits 340 and 370 provided in the barrel blocks 34 and 37. The temperature inside the dehydration zone 102 is preferably 50 to 100 ° C, more preferably 80 to 100 ° C.

  The hydrous crumb dehydrated in the dehydration zone 102 is sent to the drying zone 104 by the rotation of the screw 5. The crumbs sent to the drying zone 104 are plasticized and kneaded by the rotation of the screw 5 to form a melt, which is heated and carried downstream while being heated. When this melt reaches the vent ports 390, 410, 430, and 450 provided in the barrel blocks 39, 41, 43, and 45, 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 104 is preferably 90 to 200 ° C, more preferably 100 to 180 ° C. The internal pressure is about 1000 to 5000 kPa.

  The crumb from which moisture has been separated after passing through the drying zone 104 is sent to the outlet side by the screw 5 and is introduced into the die 4 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, for the screw 5 constituting the extruder 1, the flight shape in the region corresponding to the supply zone 100 is a square flight, so that the forward flight screw used for dehydration / drying of hydrous crumbs, etc. Compared to 5a, the space volume in the barrel 3 is increased, which makes it easier for the water-containing crumb to bite into the screw 5 and the screw 5 formed so that the flight rises substantially perpendicularly to the outer periphery of the shaft core. The hydrous crumb can be efficiently extruded.
Therefore, when dehydrating the hydrous crumb using the extruder 1, the amount of the hydrous crumb that can be introduced into the extruder 1 can be increased, and the recovery rate of the nitrile rubber dehydrated by the extruder 1 can be improved. be able to.

  Conventionally, when water-containing crumbs are dehydrated using an extruder equipped with screws 5a and 5a shown in FIG. 4, the space in the barrel 3 of the extruder due to the curved flight shape of the screws 5a and 5a. If the amount of the hydrous crumb introduced into the extruder is increased because the volume becomes small, the hydrous crumb becomes difficult to bite into the screw 5 in the supply zone 100, and the hydrous crumb stays, and the hydrous crumb is extruded. There was a problem that the feed port 310 for supplying the inside of the machine would be blocked. Such a problem becomes prominent when rubber having a low bulk density, particularly nitrile rubber, is used as the rubber constituting the hydrous crumb. That is, since the nitrile rubber has a relatively low bulk density, the hydrated crumb formed by the nitrile rubber is relatively soft and does not sufficiently bite into the screw. Adhesion is likely to occur, and the feed port 310 may be blocked by the hydrated crumb. Therefore, conventionally, when a water-containing crumb of rubber having a low bulk density such as nitrile rubber is dehydrated by the extruder 1, the recovery rate of the dehydrated nitrile rubber is determined by a motor stored in the drive unit 2. There was a problem that it was limited by the feed limit due to not being able to catch up with the introduction of the hydrous crumb into the extruder 1 instead of the torque limit.

  On the other hand, in the present embodiment, by making the flight shape of the screw 5 in the supply zone 100 be a square flight, it is possible to prevent such retention of water-containing crumbs and blockage of the feed port 310, Even when dehydrating hydrated crumbs of nitrile rubber having a low bulk density, the recovery rate of nitrile rubber can be effectively improved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in various aspects. .

  For example, in the above-described embodiment, as shown in FIG. 3, the screw 5 of the extruder 1 is biaxial, but it may be more multiaxial (3 or more), or may be single-axial. (1) may be sufficient.

  Alternatively, in the above-described embodiment, as illustrated in FIG. 3, the angular flights of the two screws 5 and 5 are arranged so as to overlap each other when viewed from the axial center of the screw 5, thereby However, the screws 5 and 5 may be non-engagement types in which the angular flights do not overlap each other as long as the extrusion of the hydrous crumb is not hindered.

  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.

Mooney viscosity (Polymer Mooney)
The Mooney viscosity (polymer Mooney) of the carboxyl group-containing highly saturated nitrile rubber was measured according to JIS K6300 (unit: (ML _{1 + 4} , 100 ° C.)).

Example 1
In a metal bottle, 225 parts of ion-exchanged water, 25 parts of an aqueous solution of sodium dodecylbenzenesulfonate having a concentration of 10% by weight, 37 parts of acrylonitrile, 4 parts of mono-n-butyl fumarate, t-dodecyl mercaptan (molecular weight regulator) After charging in order of 5 parts and replacing the internal gas with nitrogen three times, 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 latex of carboxyl group-containing highly saturated nitrile rubber (in terms of solid content) was added to and mixed with 80 parts of a sodium chloride aqueous solution having a concentration of 5% by weight to obtain a coagulated crumb. It was. 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. Next, the obtained coagulated crumb was taken out, filtered and washed with water, and then water was added to obtain a slurry containing water-containing crumb of carboxyl group-containing highly saturated nitrile rubber having a concentration of 6% by weight. The carboxyl group-containing highly saturated nitrile rubber obtained by filtering a part of the obtained water-containing crumb and then vacuum-drying overnight had a Mooney viscosity (polymer Mooney) of 62.

  And using the obtained slurry containing the hydrated crumb of carboxyl group-containing highly saturated nitrile rubber, using an extruder 1 having a configuration as shown in FIGS. 1 to 3 (manufactured by Nippon Steel Works, TEX44αII). The water-containing crumb was dehydrated.

  In the present embodiment, as the extruder 1, a twin screw extruder in which two screws 5 and 5 are provided in parallel in the barrel 3 and these screws 5 and 5 are meshed and rotated in the same direction was used.

  As the screw 5, the flight shape in the region corresponding to the supply zone 100 is the angular flight shown in FIG. 3, and the flight shape in the region corresponding to the dehydration zone 102 and the drying zone 104 is the forward flight shown in FIG. 4. Was used. In addition, regarding the angular flight of the screw 5, the ratio (height with respect to the axis of the peak 50A / height with respect to the axis of the valley 50B) described above is 1.6, and the width (thickness) of the peak 50A is 2. 0.5 mm (the width of the crest 50A / the width of the trough 50B) is 0.06, and the angle at which the angular flight rises from the screw 5 is 65 °.

  And the water-containing crumb slurry of the obtained carboxyl group-containing highly saturated nitrile rubber was supplied to the feed port 310 of the extruder 1 having such a configuration at a rate of 300 kg / hr. In this example, the internal temperature of the supply zone 100 was set to 50 ° C., the internal temperature of the dehydration zone 102 was set to 90 ° C., and the internal temperature of the drying zone 104 was set to 120 ° C.

  As a result, a sheet-like dried carboxyl group-containing highly saturated nitrile rubber was recovered from the die 4 connected to the downstream side of the barrel at a recovery rate of 20 kg / hr. As shown in Table 1, the motor of the extruder 1 has a rotation speed of 146 rpm, a torque of 29.0% of the maximum output of the motor, a current value of 77 A, a power value of 6 kW, and a specific power of carboxyl group. The weight of the highly saturated nitrile rubber contained was 0.300 kwh / kg, and the ratio (Q / Ns) between the recovered amount and the screw rotation speed was 0.137. Further, in the drying zone 104, heat was generated by shearing the hydrous crumb, and the temperature (drying temperature) in the drying zone 104 was 168 ° C.

  In this example, no hydrated crumb stayed at the feed port 310 of the extruder 1. Further, the recovered carboxyl group-containing highly saturated nitrile rubber had a residual volatile content of 0.26% of the water contained therein, and the water-containing crumb could be dehydrated satisfactorily. The recovered carboxyl group-containing highly saturated nitrile rubber had a Mooney viscosity (polymer Mooney) of 57.1. The results are shown in Table 1.

Comparative Example 1
As the screw disposed in the extruder, a screw whose flight shape in the region corresponding to the supply zone 100, the dewatering zone 102 and the drying zone 104 is a forward flight shown in FIG. 4 is used. Except for changing the current value and the power value as shown in Table 1, the production of the carboxyl group-containing highly saturated nitrile rubber and the dehydration of the water-containing crumb of the carboxyl group-containing highly saturated nitrile rubber were carried out in the same manner as in Example 1. went. The results are shown in Table 1.

Comparative Example 2
Production of carboxyl group-containing highly saturated nitrile rubber, and carboxyl group-containing, in the same manner as Comparative Example 1, except that the number of revolutions, torque, current value, and power value of the motor of the extruder were changed as shown in Table 1. The water-containing crumb of highly saturated nitrile rubber was dehydrated. The results are shown in Table 1.

  As shown in Table 1, as the screw 5 of the extruder 1, the flight shape in the region corresponding to the supply zone 100 is a square flight so that the hydrated crumb stays in the feed port 310 of the extruder 1. Furthermore, the residual volatile content of water was as low as 0.26%, and the carboxyl group-containing highly saturated nitrile rubber that was well dehydrated could be recovered at a high recovery rate of 20 kg / hr ( Example 1).

On the other hand, it was confirmed that the recovery rate of the carboxyl group-containing highly saturated nitrile rubber was reduced when the flight shape in the region corresponding to the screw supply zone 100 was changed to the forward flight instead of the square flight (Comparative Example). 1, 2).
Further, when the screw having the shape as in Comparative Examples 1 and 2 was used and the amount of the hydrous crumb supplied to the extruder was set to the same amount as in Example 1, that is, dehydrated carboxyl group-containing highly saturated When the recovery rate of nitrile rubber was adjusted to be about 20 kg / hr, water crumbs stayed at the feed port 310 of the extruder.

DESCRIPTION OF SYMBOLS 1 ... Extruder 2 ... Drive unit 3 ... Barrel 31-45 ... Barrel block 4 ... Die 5, 5a ... Screw

Claims (4)

A method of dewatering a hydrous crumb containing crumb-like nitrile rubber using an extruder in which a screw is rotatably disposed inside a barrel,
A method for dehydrating a hydrous crumb, characterized in that the flight shape of the screw in the region corresponding to the feed zone for feeding the hydrous crumb of the extruder is a square flight.   The method for dewatering a hydrous crumb according to claim 1, wherein after the solid content concentration of the slurry containing the hydrous crumb is adjusted to 5 to 10% by weight, the slurry containing the hydrous crumb is supplied to the extruder. The dehydration method for hydrous crumbs according to claim 1 or 2, wherein the nitrile rubber has a Mooney viscosity (ML _{1 + 4} , 100 ° C) of ₅ to 200.   The dewatering method for hydrous crumbs according to any one of claims 1 to 3, wherein a dewatering zone and a drying zone are sequentially provided on the downstream side of the supply zone of the extruder.

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