JP2003277434A - Method for producing copolymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an α,β-ethylenically unsaturated nitrile-conjugated diene copolymer having alkylthio groups of a specific structure introduced into the molecule and exhibiting high-speed vulcanizability with which the copolymer is obtained in a few steps for a short drying time, and an apparatus therefor. <P>SOLUTION: The method for producing the α,β-ethylenically unsaturated nitrile-conjugated diene copolymer comprises feeding an unsaturated nitrile- conjugated diene copolymer obtained by emulsion polymerization and having the alkylthio groups of the specific structure introduced into the molecule to an extruder and continuously carrying out coagulation, dehydration and drying. Thereby, the α,β-ethylenically unsaturated nitrile-conjugated diene copolymer is obtained in the few steps for the short drying time. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an α, β-ethylenically unsaturated nitrile-conjugated diene-based copolymer having an alkylthio group having a specific structure introduced into its molecule, and a recovery apparatus.

[0002]

2. Description of the Related Art Injection molding is widely used for molding acrylonitrile-butadiene rubber (hereinafter referred to as NBR), which is used in fields where oil resistance and heat resistance are required, and high-speed vulcanization There has been a demand for an NBR that has the following characteristics and has less mold contamination.

In order to meet the above demand, unsaturated nitrile-conjugated diene copolymers having an alkylthio group having a specific structure introduced into the molecule have been found, and problems such as vulcanizability and mold contamination have been improved. (JP-A-8-67706, JP-A-8-67706)
100030).

As a method for producing an unsaturated nitrile-conjugated diene copolymer having an alkylthio group having the above-mentioned specific structure introduced into the molecule, as described in JP-A-8-100030, (1) From the step of adding a copolymer latex to a calcium chloride solution after the polymerization reaction to coagulate, (2) taking out the produced crumb, (3) washing the produced crumb with water, and (4) drying under reduced pressure under heating. A method comprising is described.

However, the manufacturing method of the publication has a problem that the number of steps is large, and since the vacuum drying method is used, the moisture taken into the crumb does not evaporate easily and the drying time becomes long.

[0006]

In view of the above circumstances, an object of the present invention is to reduce the amount of α, β-ethylenically unsaturated nitrile-conjugated diene copolymer having an alkylthio group having a specific structure introduced into the molecule. It is an object of the present invention to provide a method for efficiently producing a polymer with a small number and a short drying time, and a recovery device for the polymer.

[0007]

Means for Solving the Problems The present inventor has conducted extensive studies to achieve the above object, and found that α, β-ethylene having an alkylthio group of a specific structure obtained by emulsion polymerization introduced into the molecule. By supplying a latex of a water-soluble unsaturated nitrile-conjugated diene copolymer to an extruder and continuously performing coagulation, dehydration and drying, it is possible to obtain the polymer in a small number of steps and a short drying time. I found it.

That is, the method for producing a copolymer according to the present invention has 12 to 16 carbon atoms having at least 3 tertiary carbon atoms, at least one of which is directly bonded to a sulfur atom. Α, β having an alkylthio group of 1) in the molecule at a ratio of 0.03 mol or more per 100 mol of monomer units constituting the molecule and having a Mooney viscosity of 15 to 150.
-A method for producing an ethylenically unsaturated nitrile-conjugated diene-based copolymer, wherein the latex of the copolymer is supplied to an extruder, and coagulation, dehydration, and drying are continuously performed. .

Further, the extruder has at least a solidification zone in which a screw is rotatably driven inside a barrel, and the axial length of a solidification screw block formed in a region corresponding to the solidification zone. Is L1 (mm), the number of valleys is n (pieces), and the outer diameter of the screw is D (mm), the coagulation screw block obtained by H = L1 / (D × n) Pitch index H
Is preferably 0.5 or less.

Further, in the screw, it is preferable that 10 to 60% of the screw block for coagulation is constituted by a kneading disc.

Then, it is preferable to use a biaxially meshing type screw which rotates in the same direction.

Further, the copolymer recovery apparatus of the present invention is an apparatus for recovering the copolymer, and is a barrel in which at least a solidification zone is formed, and is rotatably driven inside the barrel. And an extruder having a screw, the screw has a coagulation screw block formed in a region corresponding to the coagulation zone,
The length of the solidification screw block is L1 (mm), the number of valleys is n (pieces), and the outer diameter is D (mm).
Then, the pitch index H of the coagulating screw block obtained by H = L1 / (D × n) is 0.5 or less.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
In the production method of the present invention, an alkylthio group having 12 to 16 carbon atoms, which has at least three tertiary carbon atoms, and at least one of the carbon atoms is directly bonded to a sulfur atom, constitutes a molecule. It has 0.03 mol or more per 100 mol of the monomer unit in the molecule and has a Mooney viscosity of 15 to 15
The present invention relates to an α, β-ethylenically unsaturated nitrile-conjugated diene-based copolymer having a value of 0, wherein latex of the copolymer is fed to an extruder to continuously perform coagulation, dehydration and drying. Characterize.

The Mooney viscosity of the copolymer is preferably 1
5 to 150, particularly preferably 20 to 90. When the Mooney viscosity is less than 15, only a molded product having low strength can be obtained, and there is a problem that a large amount of burrs is generated in injection molding. Further, when the Mooney viscosity exceeds 150, the viscosity increases, and it becomes difficult to perform not only injection molding but also molding.

The copolymer has at least 3 in the molecule.
1 tertiary carbon atom and a carbon atom having a sulfur atom directly bonded to at least one tertiary carbon atom therein
As the alkylthio group of 2 to 16, 1,1-di (2,2
2-dimethylpropyl) -1-ethylthio group and 1,
1-di (2,2-dimethylpropyl) -1- (2,2,
The 4,4-tetramethylpentyl) -1-ethylthio group may be mentioned, and these may be contained alone or in combination in one molecule. Among them, 1,1-di (2,2-
The dimethylpropyl) -1-ethylthio group is particularly preferred.

In the molecule of the copolymer, the above-mentioned alkylthio group is 0.03 mol or more, preferably 0.07 mol or more, more preferably 0.09 mol, per 100 mol of the monomer unit constituting the molecule. There exists more. The amount of the alkylthio group is usually 0.3 mol or less.

When the amount of the above-mentioned alkylthio group is excessively low, high crosslinking efficiency cannot be obtained in vulcanization at high temperature for a short time such as injection molding, and therefore tensile stress and impact resilience of the molded product are not improved. High speed vulcanization is not achieved.
Further, as the amount of the alkylthio group increases, the scorch time (T ₅ ) shortens remarkably, and further, the mold fouling property is significantly improved, which enables injection molding with high productivity. Particularly when the amount is 0.09 mol or more, the crosslinking efficiency is significantly improved, and the maximum torque in the vulcanization curve measured by using the oscillating disc rheometer is dramatically increased.

The amount of bound nitrile of the copolymer is preferably 10 to 80% by weight, particularly preferably 20 to 50% by weight. Further, the weight average molecular weight (Mw) of the copolymer
The ratio (Mw / Mn) between the number average molecular weight (Mn) and the number average molecular weight (Mn) is usually 2.3 to 5.5, preferably 2.7 to 4. Mw /
If the Mn is too large, even if the number average molecular weight is 35,000.
Even if an appropriate amount of components of 0 or less is contained, workability is poor.

The copolymer is obtained by emulsion polymerization of an α, β-ethylenically unsaturated nitrile monomer, a conjugated diene monomer and another monomer copolymerizable therewith in the presence of a molecular weight modifier. It is a copolymer obtained by polymerizing.

The molecular weight regulator used in polymerizing the copolymer includes 2,2,4,6,6-pentamethylheptane-4-thiol and 2,2,4,6,6,8,
8-heptamethylnonane-4-thiol can be mentioned.
Among them, 2,2,4,6,6-pentamethylheptane-4-thiol is particularly preferable, and the α, β-ethylenically unsaturated nitrile-conjugated diene copolymer produced by using the thiol compound is Very fast vulcanizability.

Α, β used in polymerizing the copolymer
-Specific examples of the ethylenically unsaturated nitrile monomer include:
Examples thereof include acrylonitrile, methacrylonitrile and α-chloroacrylonitrile. Examples of the conjugated diene monomer include 1,3-butadiene, 2,3-dimethylbutadiene, isoprene and 1,3-pentadiene. These can usually be used in the range of 20 to 90% by weight in all the monomers.

When the copolymer is polymerized, in addition to these monomers, a part of all the monomers may be copolymerized with other copolymers, if necessary, within a range in which the effects obtained by the present invention are not impaired. It is also possible to replace with possible monomers. Other copolymerizable monomers include vinyl-based monomers such as styrene, α-methylstyrene and vinylpyridine; non-conjugated diene-based monomers such as vinylnorbornene, dicyclopentadiene and 1,4-hexadiene. Unsaturated carboxylic acid monomers such as (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid Hexyl, cyclohexyl (meth) acrylate,
Unsaturated carboxylic acid ester monomers such as lauryl (meth) acrylate; further, polyethylene glycol (meth) acrylate, polypropylene glycol (meth)
Examples thereof include monomers such as acrylate, epoxy (meth) acrylate, and urethane (meth) acrylate. These are generally 40% by weight or less, preferably 2% by weight based on the total monomers.
It can be used in the range of 0% by weight or less.

The emulsifier used in polymerizing the copolymer may be any conventionally known emulsifier and is not particularly limited. For example, anionic type (sulfuric acid ester salt of higher alcohol, alkylbenzene sulfonate, aliphatic carboxylic acid ester sulfonate, etc.), nonionic type (alkyl ester type of polyethylene glycol, alkyl phenyl ether type, alkyl ether type, etc.) and Amphoteric surfactants (constitutes carboxylate, sulfate, sulfonate, phosphate, phosphate as anion part and amine salt, quaternary ammonium salt as cation part) and the like. To be The amount of the emulsifier used is not particularly limited, but is usually 0.05 to 10 parts by weight, preferably 0.5 to 3 parts by weight, per 100 parts by weight of the monomer.

The polymerization initiator used for polymerizing the copolymer may be any conventionally known radical polymerization initiator and is not particularly limited. For example, an inorganic peroxide such as hydrogen peroxide or potassium persulfate, or an organic peroxide such as cumene hydroperoxide, diisopropylbenzene hydroperoxide or paramenthane hydroperoxide, and a divalent iron salt or tetraethylene pentaoxide. A redox catalyst in which a reducing agent such as an amine is combined can be used. The redox catalyst is preferably used when conducting polymerization at low temperature.

The emulsion polymerization at the time of polymerizing the copolymer may be a batch system, a semi-batch system or a continuous system, but the batch system is preferred. The batch type emulsion polymerization includes, for example, adding deionized water, a monomer mixture and an emulsifier to an emulsion polymerization tank equipped with a stirrer and mixing them, and then adding a polymerization initiator, a cocatalyst and a molecular weight modifier to the emulsion polymerization. Do. Polymerization is usually 0-7
It is carried out in a temperature range of 0 ° C, preferably 5 to 50 ° C.

When polymerizing the copolymer, a polymerization terminator such as hydroxylamine is added to terminate the polymerization when the emulsion polymerization reaction reaches a predetermined conversion rate. Next, the copolymer latex obtained by removing the residual monomer by heating, steam distillation and the like is supplied to an extruder for coagulation / dehydration / drying.

The solid content of the copolymer latex fed to the extruder is usually about 5 to 50% by weight, preferably 1
It is about 0 to 40% by weight.

Specific examples of the extruder used in the present invention are shown in FIGS.
As shown in FIG. A copolymer recovery apparatus according to the present invention is an apparatus for recovering a copolymer from a latex of a copolymer, and is a barrel in which at least a solidification zone is formed, and is rotatably and rotatably disposed inside the barrel. An extruder having a screw, the screw having a coagulation screw block formed in a region corresponding to the coagulation zone, and the axial length of the coagulation screw block is L1 ( mm), the number of valleys is n (pieces), and the external shape of the screw is D (mm), H
= L1 / (D × n), the pitch index of the solidification screw block is 0.5 or less.

It is preferable to use a screw having a ratio (L1 / D) of the axial length L1 of the coagulating screw block to the outer diameter D of the screw of 12 or less, and particularly 8 or less. preferable.

When the axial length of the screw is L (mm), it is preferable to use a screw having a ratio (L / D) of the length L to the outer diameter D of 60 or less, and 48 or less. It is particularly preferable to use a certain screw because the extruder installation space can be reduced and the power consumption can be reduced.

The length of the screw block for coagulation is 10 to 10
It is preferable to use a screw of which 60% is composed of a kneading disk, because the coagulation of the copolymer can be further promoted.

A drainage zone is preferably provided on the downstream side of the solidification zone formed inside the barrel, and a washing zone, a dehydration zone and a drying zone are sequentially provided on the downstream side of the drainage zone. Is particularly preferred. In this case, the coagulation zone, the dehydration zone and the drying zone are respectively formed inside a plurality of barrels (a plurality of devices) arranged apart from each other, and the plurality of barrels are connected to each other via, for example, a conveyor. You can do it. However, from the viewpoint of reducing the installation space, it is preferable that the coagulation zone, the dehydration zone and the drying zone are formed inside a single barrel (single apparatus). The barrel is usually composed of a plurality of barrel blocks.

A high-concentration coagulant (residual coagulant) obtained in the coagulation zone is provided by providing a drainage zone downstream of the coagulation zone formed inside the barrel and before the cleaning zone. Most of the coagulant can be efficiently removed from the crumb slurry containing. As a result, it is possible to reliably remove the low-concentration coagulant remaining in the subsequent washing zone, and to ensure that the coagulant residual amount contained in the copolymer finally recovered through the dehydration zone and the drying zone is the predetermined amount. It can be less than or equal to the value.

In the present invention, it is also possible to control the amount of the coagulant remaining in the copolymer to a desired value by changing the operating conditions such as the number of revolutions and the amount of washing water.

Generally, the residual amount of the coagulant is preferably 1000 ppm or less. If more than 1000 ppm of the coagulant remains in the recovered copolymer, the vulcanized physical properties and corrosiveness of the product deteriorate.

Further, in the present invention, it is preferable to determine the type of the coagulant, the amount of the coagulant supplied, and the amount of the copolymer supplied so that the coagulation is sufficiently performed in the coagulation zone. If the coagulation is insufficient, uncoagulated latex flows out from the drainage zone or the dehydration zone, and the copolymer recovery rate decreases.

Further, the screw is a biaxially meshing type and is of the same direction rotating type, so that self-cleaning property can be imparted, and compared with the conventional coagulation tank system for coagulating the copolymer by the coagulation tank, It is also possible to realize long-term continuous operation.

The extruder used in the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing an embodiment of an extruder used in 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 sectional view taken along line III and line III-III in FIG.
FIG. 3 is a partially cutaway schematic view for explaining a screw block for solidifying the screw of FIG. 2.

As shown in FIG. 1, the extruder 2 used in the present invention has 12 divided barrel blocks 41 to 52.
Has a single barrel 4. In the present embodiment, inside the barrel, the solidification zone 100 and the drainage zone 10 are provided.
2, the washing zone 104, the dehydration zone 106, and the drying zone 108 are sequentially formed from the upstream side to the downstream side of the barrel 4.

The coagulation zone 100 is a region where the copolymer latex is brought into contact with a coagulant to coagulate the copolymer to form a crumb-like copolymer slurry (crumb slurry). The drainage zone 102 is a region in which a liquid (serum water) generated after solidification of the copolymer is separated from the crumb slurry and discharged to form a crumb in a water-containing state. The washing zone 104 is an area for washing the water-containing crumb. The dehydration zone 106 is a region for dehydrating and discharging cleaning water from the cleaned crumb. The drying zone 108
This is the area where the dried crumbs are dried.

In this embodiment, the barrel blocks 41, 4
The inside of 2 corresponds to the coagulation zone 100, the inside of the barrel block 43 corresponds to the drainage zone 102, the inside of the barrel blocks 44 to 47 corresponds to the washing zone 104, and the inside of the barrel blocks 48 and 49 corresponds to the dehydration zone 106. The inside of the barrel blocks 50 to 52 corresponds to the drying zone 10
Corresponds to 8. The number of installed barrel blocks is not limited to the aspect of the present embodiment.

A feed port 412 for receiving the copolymer latex and the coagulant is formed in the barrel block 41 forming a part of the coagulation zone 100. The barrel block 43 forming the drainage zone 102 is formed with a discharge slit 432 for discharging the serum water separated from the water slurry of the copolymer after coagulation. Cleaning zone 104
The barrel block 44 forming a part of the above has a wash water feed port 442 for receiving wash water, and the barrel block 47 has a drain slit 472 for discharging wash drain to the outside. The barrel block 49 forming a part of the dehydration zone 106 has a dehydration slit 49 for discharging the dehydrated drainage removed from the cleaned crumb to the outside.
2 is formed. The barrel block 51 forming a part of the drying zone 108 has a vent port 51 for deaeration.
2 is formed.

Inside the barrel 4, a screw 7 as shown in FIG. 2 is arranged. A drive means such as a motor for driving the screw 7 is connected to the base end of the screw 7, and thereby the screw 7 is rotatably held. The shape of the screw 7 is not particularly limited, but preferably, the screw block having various screw configurations and the kneading disk can be appropriately combined and configured.

In this embodiment, the screw 7 includes the above-mentioned zones 100 to 108 formed inside the barrel 4.
Each screw block is formed in a region corresponding to. The structure of each screw block is as follows.

As shown in FIGS. 2 and 3, in this embodiment, the axial length of the coagulating screw block is L1.
(Mm), and the number of valleys 7B (see FIG. 4) is n (pieces)
And when the outer diameter of the screw 7 is D (mm),
The pitch index H of the solidification screw block, which is obtained by H = L1 / (D × n), is preferably 0.5 or less, particularly preferably 0.4 or less, and further preferably 0.35 or less. When the pitch index H is larger than 0.5, the coagulation becomes insufficient due to the properties of the supplied copolymer, and the uncoagulated copolymer is discharged as latex from the drain slit, so that the recovery rate decreases. There is.

The number of valleys of the coagulation screw block may be counted by looking at the coagulation screw block from above. Kneading disk 8 (details will be described later)
When counting the number of troughs, it is also necessary to count between the plates whose phases are shifted (see FIG. 4).

In the present embodiment, the solidification screw block formed in the region corresponding to the solidification zone 100 is
In particular, from the viewpoint of promoting solidification, the kneading disk 8
Is included.

The kneading disk 8 has a cross-sectional shape such as a pseudo-elliptical shape, an oval shape or a truncated triangle (pseudo-elliptical shape in FIG. 3) and a certain thickness, and the symmetry axis of the cross-sectional shape. While being shifted by a predetermined angle (30 degrees in FIG. 3), a plurality of sheets (6 sheets in FIG. 3) are stacked, and the screw shaft is fixed and used so as to correspond to the rotation center axis of the cross-sectional shape. Pseudo-oval here means both ends of the major axis of the ellipse, oval means both ends of parallel strips, and truncated triangle means the part including the vertices of an equilateral triangle, with the center of rotation of each figure as the center. A shape cut with an arc. In either case, the inner wall surface 4 of the barrel 4
The end portions of the respective disks are provided in a so as to maintain a predetermined (about 1 to 5 mm) clearance (gap). In the case of an oval shape or a truncated triangle, each side may be concave to form a drum shape or a triangular pincushion shape.

In the present embodiment, the kneading disk 8 with respect to the axial length L1 of the solidification screw block 8
The length occupies preferably 10 to 60%, more preferably 20 to 50%, particularly preferably 30 to 40%.
Therefore, the number of the disks is preferably about 3 to 9.
Kneading disk 8 with coagulation screw block
If the ratio is too large, the feed amount will be insufficient, and if it is too small, coagulation will be insufficient. The present invention can be carried out by using a screw having a narrow pitch interval of three or more threads instead of the kneading disk, but in general, if the number of threads increases, the manufacturing becomes difficult and the manufacturing cost becomes high. It is preferred to use the disk 8.

If the drainage screw block, the washing screw block, the dehydration screw block and the drying screw block formed in the region corresponding to the drainage zone 102 to the drying zone 108 are constituted by normal forward feed screws, for example. Good. If necessary, a reverse feed screw or a kneading disc may be included.

As shown in FIG. 3, in the present embodiment, two such screws 7 are used to form a twin-screw extruder in which shafts are in parallel and meshed with each other. That is, with the two screws 7, 7, one screw 7
The ridge 7A (see FIG. 4) of the other screw 7
B (see FIG. 4) is engaged, and the trough portion 7B of one screw 7 is in mesh with the crest portion 7A of the other screw 7, which is a biaxial meshing type. However, it may be a multi-axis type (three or more) or a single axis type (one). However, in view of the mixing property of the solidification zone 100, it is preferable to use the biaxial meshing type as in the present embodiment. The two screws 7 may rotate in the same direction or in different directions, but from the viewpoint of self-cleaning performance, a type of rotating in the same direction is preferable.

In the present embodiment, a die 6 is provided downstream of the above-mentioned barrel block 52, which is manufactured by extruding the coagulated, dehydrated and dried copolymer in the barrel 4 into a predetermined shape. It is connected. A cutting mechanism (not shown) is attached to the die 6, and the strand-shaped copolymer extruded from the die is cut into an appropriate size to obtain pellets having a predetermined shape. As the cutting mechanism, a mechanism may be adopted in which the extruded strand is immediately cut by a hot-cutting device, or cooled by a cooling tank and cut by a cutter.

Next, a method for producing a copolymer using the extruder 2 will be described, but the present invention is not limited to these embodiments. After the emulsion polymerization of the conjugated diene monomer, the α, β-ethylenically unsaturated nitrile monomer and the other monomer copolymerizable therewith, the residual monomer is removed and at least 3 12 to 1 carbon atoms having a tertiary carbon atom, at least one of which is directly bonded to a sulfur atom
The alkylthio group of 6 is used as the monomer unit 10 which constitutes the molecule.
It has in the molecule at a ratio of 0.03 mol or more per 0 mol,
A latex of an α, β-ethylenically unsaturated nitrile-conjugated diene copolymer having a Mooney viscosity of 15 to 150 is obtained. The latex of the obtained copolymer is introduced into the coagulation zone 100 from the feed port 412 together with the coagulant.

The coagulant to be introduced is not particularly limited, and examples thereof include inorganic acids (sulfuric acid, hydrochloric acid, etc.), organic acids (acetic acid, etc.), inorganic salts (calcium chloride, magnesium chloride, magnesium sulfate, aluminum sulfate, polymers). Flocculants, etc.), and mixtures thereof.
It may be appropriately determined depending on the amount of the coagulant used and the type and amount of the emulsifier used in the latex of the copolymer. Among them, as the coagulant, inorganic salts are preferable, and calcium chloride is more preferable.

The coagulant does not necessarily have to be directly supplied to the coagulation zone 100 from the feed port 412, but may be supplied after being premixed with the latex of the copolymer.

The latex of the copolymer introduced into the coagulation zone 100 and the coagulant are brought into contact with each other by the rotation of the screw 7, and the polymer is coagulated to form a crumb having a diameter of about 5 to 30 mm and suspended in water. A slurry liquid (crumb slurry) having a crumb concentration of about 20% by weight is formed. This crumb slurry contains 0.4% coagulant (residual coagulant).
It is contained at a high concentration of about wt% or more.

The crumb slurry formed in the solidification zone 100 is sent to the drainage zone 102 by the rotation of the screw 7. In the drainage zone 102, the barrel block 43
The high-concentration coagulant contained in the crumb slurry is discharged as serum water from the slit 432 provided in the coke slurry, and the coagulant concentration is reduced to about 0.15% by weight or less, and 6 to 3
A hydrated crumb containing about 1% by weight of water can be obtained.

The water-containing crumb obtained in the drainage zone 102 is sent to the washing zone 104 by the rotation of the screw 7. In the cleaning zone 104, the barrel block 44
The cleaning water is introduced into the inside from the cleaning water feed port 442 provided in the above, the above-mentioned crumb is cleaned, and the cleaned drainage is discharged from the slit 472 provided in the barrel block 47. The coagulant concentration is further reduced to about 0.05% by weight or less, and crumbs containing about 5 to 30% by weight of water are obtained.

The crumb obtained in the washing zone 104 is sent to the dehydration zone 106 by the rotation of the screw 7.
In the dehydration zone 106, moisture is discharged from the slit 492 formed in the barrel block 49 so that the amount of moisture is 2-9.
Crumbs adjusted to about wt% are obtained.

The crumb obtained in the dehydration zone 106 is sent to the drying zone 108 by the rotation of the screw 7.
The crumb sent to the drying zone 108 is plasticized and kneaded by the rotation of the screw 7 to become a melt, which generates heat and is conveyed to the downstream side while raising the temperature. When the melt reaches the vent port 512 provided in the barrel block 51, the pressure is released, so that the water contained in the melt is separated and vaporized. The separated vaporized water (steam) is discharged to the outside through a vent pipe (not shown). Drying zone 108
The internal temperature is about 120 to 180 ° C., and the pressure is about 1000 to 5000 KPa.

The crumb from which the water content has passed through the drying zone 108 is sent to the outlet side by the screw 7 and is substantially free of water content (water content of 0.5% by weight or less). In this case, after being discharged in the form of a strand, for example, it is introduced into a pelletizer (not shown), cut, and made into a suitable length (pellet).

In the extruder 2 according to this embodiment, the pitch index H of the coagulating screw block of the screws 7, 7 arranged inside the extruder 2 is set to 0.5 or less, and the shaft of the coagulating screw block is Direction length L1 and outer diameter D
And the ratio (L1 / D) is preferably 12 or less. Therefore, even if the ratio of the length L to the outer diameter D (L / D) is 60 or less when the axial length of the screw 7 is L (mm), the latex of the copolymer is Thus, a copolymer having a small residual amount of coagulant can be recovered in high yield. In particular, by including the kneading disk 8 in a predetermined ratio in the coagulation screw block, the coagulation of the copolymer can be further promoted and the residual amount of the coagulant contained in the recovered copolymer can be further reduced. It is possible.

In this embodiment, the screws 7, 7 are of the biaxial mesh type and of the same rotation type so that self-cleaning property can be imparted and the coagulation tank for coagulating the copolymer by the conventional coagulation tank. Long-term continuous operation can also be realized compared to the system. In this embodiment, the coagulation zone 100, the dehydration zone 106 and the drying zone 10
Since 8 is formed in the single barrel 4, it is advantageous in terms of space saving and cost saving.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be carried out in various modes without departing from the scope of the present invention.

[0065]

The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited by these examples. Further, unless otherwise specified, parts and% are based on weight.

Each measured value was measured as follows. (1) Mooney viscosity According to Japanese Industrial Standard JIS K6383, about 4 copolymers
It was measured at 100 ° C. using 0 gram. (2) Amount of bound nitrile According to Japanese Industrial Standard JIS K6384, the nitrogen content in the copolymer was measured by the Kjeldahl method, and the amount of bound nitrile was calculated (unit:%). (3) Molecular weight gel permeation (solvent: Number average molecular weight (M
n) was measured.

(4) 1,1-di (2,2) in the copolymer
-Dimethylpropyl) -1-ethylthio group concentration After dissolving the copolymer in benzene, in methyl alcohol
The purified copolymer is obtained by repeating the procedure of solidifying at
The NMR measurement was carried out on.¹H-NMR measurement (4
00MHz), the terminal methyl group in the ethylthio group
The peak due to the protons of
Was issued, and in addition,^ThirteenC-NMR measurement (100 MHz)
Due to the carbon of the methylene group in the ethylthio group.
Peak is detected around 54.6 ppm. Copolymer
The quantification of the concentration of the ethylthio group in ¹For H-NMR measurement
4.8 and the integral value of the peak due to the terminal methyl group
Unsaturation of butadiene detected at about 5.8 ppm
Ratio with the integral value of the peak due to the protons bound to each other
Was calculated by using (unit: mol%).

(Polymerization Example) Deionized water 160 was added to the polymerization reaction tank.
Parts, acrylonitrile 36 parts, butadiene 64 parts, potassium oleate 2 parts as an emulsifier, potassium phosphate 0.1 part as a stabilizer, and molecular weight regulators 2,2,4.
6,6-Pentamethylheptane-4-thiol (hereinafter,
PMHT) (0.27 parts), ferrous sulfate (0.015 parts) as an activator, and paramenthane hydroperoxide (0.05 parts) as a polymerization initiator are added, and the mixture is sufficiently stirred at 9 ° C. Emulsion polymerization was started. Next, at the time when the polymerization conversion rate was 50%, 0.07 part of PMHT was added to continue the polymerization. Polymerization conversion rate is 85% after 12 hours
Therefore, 0.2 part of hydroxylamine sulfate was added to stop the reaction, steam was blown in to heat and remove the residual monomer, and then 2 parts of alkylated phenol was added as an antioxidant. . The resulting copolymer has a Mooney viscosity of 85, a bound acrylonitrile content of 34%,
The 1,1-di (2,2-dimethylpropyl) -1-ethylthio group concentration was 0.08 mol%.

Example 1 In this example, as shown in FIG. 1, two screws (total length 1920 mm, outer diameter D = 40 mm, L
/ D = 48) 7 and 7 are provided in parallel, these screws 7 and 7 are rotationally driven in the same direction, and the ridge portion 7A of one screw 7 (see FIG. 4) is attached to the other screw 7.
A twin-screw mesh type screw extruder 2 rotating in the same direction was used in a state of meshing with the valley portion 7B (see FIG. 4).

The screw 7 has a solidification screw block formed in a region corresponding to the solidification zone 100 formed inside the single barrel 4. In the present embodiment, this solidification screw block is It consisted of four kneading disks 8 and two full flight combinations. The kneading disk 8 constituted 30% of the length of the solidification screw block. The axial length L1 of the coagulation screw block is 320 mm and its outer diameter D
Was 40 mm and the number of valleys was 28. Therefore, the pitch index H (L1 / L1 of the screw block for coagulation
(D × n)) was 0.28 and (L1 / D) was 8.

The screw 7 has a drain zone 102 and a cleaning zone 10 formed inside the single barrel 4.
4. A drainage screw block, a washing screw block, a dehydration screw block and a drying screw block, which are formed in the regions corresponding to the dehydration zone 106 and the drying zone 108, respectively, are provided with two full flight and kneading disks. Composed of.

The screw 7 has a drainage zone 102 and a cleaning zone 10 formed inside the single barrel 4.
4. A drainage screw block, a washing screw block, a dehydration screw block and a drying screw block, which are formed in the regions corresponding to the dehydration zone 106 and the drying zone 108, respectively, are provided with two full flight and kneading disks. Composed of.

Feed port 4 of extruder 2 having such a configuration
The copolymer latex obtained in Polymerization Example 12 (solid content: 30% by weight) was supplied at a rate of 300 kg / hr. At that time, a 5 wt% calcium chloride aqueous solution as a coagulant was supplied at a rate of 40 kg / hr. Then, while supplying cleaning water to the cleaning zone 104 at a rate of 250 kg / hr, the copolymer was recovered at a screw rotation speed of 360 rpm.

As a result, from the die 6 connected to the downstream side of the barrel, 88.9 kg of the sheet-like dried copolymer was obtained.
It was recovered at a rate of / hr (recovery rate 98.5%). The water content of the recovered copolymer was 0.3% by weight, and the amount of residual coagulant (inorganic salt) was 420 ppm, which was a satisfactory property as a product. The amount of residual coagulant was measured by potentiometric titration.

In this example, a copolymer product of 10
The time required to obtain 0 kg was 67 minutes. Example 2 The pitch of the portion other than the kneading disk of the screw block for coagulation was widened so that the number of valleys was 18. That is, the pitch index H of the screw block for coagulation is 0.44.
The copolymer was recovered in the same manner as in Example 1 except for the above.

As a result, from the die 6 connected to the downstream side of the barrel, 87.4 kg of the sheet-like dried copolymer was obtained.
It was recovered at a rate of / hr (recovery rate 96.7%). The water content of the recovered copolymer was 0.4% by weight, and the amount of residual coagulant (inorganic salt) was 570 ppm, which was a satisfactory property as a product. The amount of residual coagulant was measured by potentiometric titration.

In this example, a copolymer product of 10
The time required to obtain 0 kg was 69 minutes.

Comparative Example 183 kg of a 5 wt% calcium chloride aqueous solution was placed in a 1 m3 tank equipped with a stirrer, and 345 kg of the latex of the copolymer obtained in Polymerization Example (solid content 30 wt%) was 345 kg while maintaining the stirring state. The entire amount was added at a rate of / hr to carry out the coagulation operation. (Time for coagulation process 65 minutes)

Next, the produced crumb slurry was supplied to a vibrating screen to separate it from water, and was washed with 345 kg of washing water to remove residual calcium chloride, emulsifier and the like. (30 minutes for cleaning process)

Water-containing crumb after cleaning (water content 53%) 21
Put 5 kg in a large vacuum dryer, 50 ℃, -600
Drying was carried out under the condition of mmHg, and after 10 hours, the water content was 0.
The operation was stopped because it became 5%, and dried copolymer 10
0 kg was obtained. (Recovery rate 96.1%, drying process time 600 minutes)

The water content of the recovered copolymer was 0.5% by weight, and the amount of residual coagulant (inorganic salt) was 650 ppm, which was satisfactory as a product. It took 695 minutes and had extremely poor productivity, and required installation of a large number of equipment such as a coagulation tank, a vibrating screen, and a large vacuum dryer, resulting in an increase in equipment cost and installation area. The amount of residual coagulant was measured by potentiometric titration.

[Brief description of drawings]

FIG. 1 is a schematic view showing an extruder used in the present invention.

FIG. 2 is a schematic diagram showing a screw arranged inside the extruder of FIG.

FIG. 3 is a line III-III of FIG. 1 and a line II of FIG.
It is sectional drawing which follows the I-III line.

4 is a partially cutaway schematic view for explaining a solidifying screw block of the screw of FIG.

[Explanation of symbols]

2 ... Extruder 4 ... barrel 4a ... Inner wall surface 41-52 ... Barrel block 432, 472 ... Drainage slit 492 ... Dehydration slit 512 ... Vent port 6 ... Die 7 ... Screw 7A ... Yamabe 7B ... Tanibe 8 ... Kneading disc

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4J100 AM02P AM03P AS01Q AS02Q                       AS03Q AS04Q BB01P CA04                       CA27 DA09 EA07 FA04 FA20                       GC07 GC16 GC25 GC37

Claims (5)

[Claims] 1. A monomer constituting a molecule having an alkylthio group having 12 to 16 carbon atoms, which has at least 3 tertiary carbon atoms, and at least one of the carbon atoms is directly bonded to a sulfur atom. A method for producing an α, β-ethylenically unsaturated nitrile-conjugated diene-based copolymer having a Mooney viscosity of 15 to 150 at a ratio of 0.03 mol or more per 100 mol of units, wherein A method for producing a copolymer, which comprises feeding a latex of the copolymer to an extruder and continuously performing coagulation, dehydration and drying. 2. The extruder has at least a solidification zone in which a screw is rotatably arranged inside a barrel,
The axial length of the solidification screw block formed in the region corresponding to the solidification zone is L1 (mm), the number of troughs is n (pieces), and the outer diameter of the screw is D (m
m), the pitch index H of the solidification screw block obtained by H = L1 / (D × n) is 0.5.
The manufacturing method according to claim 1, wherein: 3. A coagulating screw block having a length of 10
The manufacturing method according to claim 2, wherein a screw having a kneading disc of which about 60% is used. 4. The manufacturing method according to claim 1, wherein a biaxially meshing type and co-rotating type screw is used. 5. An apparatus for recovering the copolymer, which comprises an extruder having at least a barrel in which a solidification zone is formed and a screw rotatably driven inside the barrel. The screw has a coagulation screw block formed in a region corresponding to the coagulation zone, the length of the coagulation screw block is L1 (mm), and the number of valleys thereof is n (pieces), Its outer diameter is D (mm)
And a pitch index H of the screw block for coagulation, which is obtained by H = L1 / (D × n), is 0.5 or less.