JP2009203272A - Method for producing carboxyl group-containing nitrile rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a carboxyl group-containing nitrile rubber, comprising adding a coagulating agent to a latex of the carboxyl group-containing nitrile rubber to coagulate the carboxyl group-containing nitrile rubber component, by which the improvement in operability, the reduction in production processes and production apparatuses, the reduction in installation cost, and the reduction in production cost are possible. <P>SOLUTION: Provided is the method for producing the carboxyl group-containing nitrile rubber, having a process for feeding the latex of the carboxyl group-containing nitrile rubber and a coagulation solution containing the coagulating agent into a pump 10 with a crushing function, bringing the latex to contact with the coagulating agent to coagulate the carboxyl group-containing nitrile rubber component, thus obtaining a crumb-like slurry containing the crumb-like carboxyl group-containing nitrile rubber, characterized in that the carboxyl group-containing nitrile rubber is coagulated at a temperature of ≥40°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a carboxyl group-containing nitrile rubber by adding a coagulant to a carboxyl group-containing nitrile rubber latex and coagulating a carboxyl group-containing nitrile rubber component.

  In the production process of synthetic rubber, for example, a rubber-like polymer component is deposited by a coagulation / washing apparatus composed of a large coagulation tank and a washing tank, washed, and then dehydrated by a squeezer, and then a band. A rubbery polymer in a dry state is obtained by a drying device such as a dryer, a flash dryer or an extrusion dryer. In addition, a baler is usually connected to the downstream side of the drying apparatus, and the rubber-like polymer after drying is finally processed into a bale-like product in many cases.

  However, in the case of producing a rubber-like polymer by such a process, a coagulation / cleaning apparatus comprising a large coagulation tank and a washing tank is required, so that the operation is complicated, the operability is poor, and a large amount is required. A large installation space, which increases equipment costs and manufacturing costs.

  In order to solve this problem, for example, in Patent Document 1, in a method for producing a rubber-like polymer by adding a coagulating liquid to a cement-like rubber solution, a cement-like rubber is used by using a pump with a crushing function. A method of depositing a rubbery polymer component by bringing a solution and a coagulation liquid into contact is disclosed. According to the method described in this document, it is described that the operability is improved, the manufacturing process and the manufacturing equipment can be reduced, and the equipment cost and the manufacturing cost can be reduced. However, the method disclosed in this document is a method for producing a rubber-like polymer from a cement-like rubber solution obtained by solution polymerization. For example, the method disclosed in this document is replaced with a polymer. Depending on the type of polymer (for example, latex of carboxyl group-containing nitrile rubber polymer tends to be a crumb with high water content and high tackiness) when applied to latex, good rubbery polymer There was a problem that could not get.

JP-A-10-100135

  The present invention has been made in view of such circumstances, and in a method for producing a carboxyl group-containing nitrile rubber by adding a coagulant to a carboxyl group-containing nitrile rubber latex and coagulating the carboxyl group-containing nitrile rubber component, It is an object of the present invention to improve the manufacturing process and reduce the number of manufacturing processes and equipment, and to reduce equipment costs and manufacturing costs.

  The present inventors crush the coagulation of the carboxyl group-containing nitrile rubber component in a method for producing a carboxyl group-containing nitrile rubber component by adding a coagulant to the carboxyl group-containing nitrile rubber latex and coagulating the carboxyl group-containing nitrile rubber component. The inventors have found that the above object can be achieved by controlling the coagulation temperature when coagulating the carboxyl group-containing nitrile rubber component, and have completed the present invention.

That is, according to the present invention, a carboxyl group-containing nitrile rubber latex and a coagulant containing a coagulant are supplied to a pump having a crushing function, and the latex and the coagulant are brought into contact with each other. A method for producing a carboxyl group-containing nitrile rubber comprising coagulating a group-containing nitrile rubber component and obtaining a crumb slurry containing a crumb-like carboxyl group-containing nitrile rubber,
There is provided a method for producing a carboxyl group-containing nitrile rubber, wherein the carboxyl group-containing nitrile rubber component is coagulated at a temperature of 40 ° C. or higher.

  Preferably, the concentration of the coagulant in coagulating the carboxyl group-containing nitrile rubber component is 0.1 to 20% by weight with respect to the total of all components other than the carboxyl group-containing nitrile rubber. The latex of carboxyl group-containing nitrile rubber and the coagulation liquid are supplied to the pump.

  According to the present invention, since the carboxyl group-containing nitrile rubber component is coagulated using a pump having a crushing function, a conventionally used coagulation apparatus consisting of a large tank is not required. It is possible to reduce the equipment cost and the manufacturing cost. In addition, according to the present invention, since the coagulation by the pump with a crushing function is performed at a temperature of 40 ° C. or more, the carboxyl group-containing nitrile rubber component can be coagulated satisfactorily and satisfactorily. Is not taken in, has low tackiness, and crumbs do not adhere to each other.

First, the latex of carboxyl group-containing nitrile rubber according to the present invention will be described.
The carboxyl group-containing nitrile rubber constituting the latex of the carboxyl group-containing nitrile rubber according to the present invention is not particularly limited, and is produced by emulsion polymerization, and free carboxyl groups (carboxyl groups not substituted with metal salts, etc.) Nitrile rubber (unsaturated nitrile-conjugated diene copolymer rubber) may be contained, or it may be a hydrogenated product thereof. In particular, α, β-ethylenically unsaturated nitrile units and α, A carboxyl group-containing nitrile rubber having a β-ethylenically unsaturated carboxylic acid unit is preferred.

  The α, β-ethylenically unsaturated nitrile monomer forming the α, β-ethylenically unsaturated nitrile unit is not limited as long as it is an α, β-ethylenically unsaturated compound having a nitrile group, and acrylonitrile; α-halogenoacrylonitrile such as α-chloroacrylonitrile and α-bromoacrylonitrile; α-alkylacrylonitrile such as methacrylonitrile; and the like. Among these, acrylonitrile and methacrylonitrile are preferable. The content of the α, β-ethylenically unsaturated nitrile unit is preferably 10 to 60% by weight, more preferably 15 to 55% by weight, and further preferably 20 to 50% by weight. If the content of the α, β-ethylenically unsaturated nitrile unit is too small, the oil resistance may be lowered in the case of a crosslinked product, and if it is too much, the cold resistance may be lowered.

  The α, β-ethylenically unsaturated carboxylic acid constituting the α, β-ethylenically unsaturated carboxylic acid unit is an α, β-ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms, 4 to 12 carbon atoms. Α, β-ethylenically unsaturated dicarboxylic acid, monoester of α, β-ethylenically unsaturated dicarboxylic acid having 3 to 11 carbon atoms and alkanol having 1 to 8 carbon atoms.

Examples of the α, β-ethylenically unsaturated monocarboxylic acid having 3 to 12 carbon atoms include acrylic acid, methacrylic acid, ethylacrylic acid, crotonic acid, and cinnamic acid.
Examples of the α, β-unsaturated dicarboxylic acid having 4 to 12 carbon atoms include butenedionic acid such as fumaric acid or maleic acid, itaconic acid, citraconic acid, and chloromaleic acid.
Examples of monoesters of an α, β-unsaturated dicarboxylic acid having 3 to 11 carbon atoms and an alkanol having 1 to 8 carbon atoms include monomethyl maleate, monoethyl maleate, monopropyl maleate, and mono n-butyl maleate. Maleic acid monoalkyl esters; maleic acid monocycloalkyl esters such as monocyclopentyl maleate, monocyclohexyl maleate, monocycloheptyl maleate; monomethyl fumarate, monoethyl fumarate, monopropyl fumarate, mono n-butyl fumarate, etc. Monoalkyl esters of fumaric acid; monocyclic esters of fumaric acid such as monocyclopentyl fumarate, monocyclohexyl fumarate, monocycloheptyl fumarate; monomethyl itaconate, monoethyl itaconate, monopropyl itaconate Itaconic acid monoalkyl esters such as itaconic acid mono n-butyl; Itaconic acid monocycloalkyl esters such as itaconic acid monocyclopentyl, itaconic acid monocyclohexyl, itaconic acid monocycloheptyl; and the like. Of these, mono n-butyl itaconate, mono n-butyl fumarate and mono n-butyl maleate are particularly preferred.

  The content of the α, β-ethylenically unsaturated carboxylic acid unit is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, and particularly preferably 1.5 to 10% by weight. If the content of the α, β-ethylenically unsaturated carboxylic acid unit is too small, crosslinking in the case of a crosslinked product may be insufficient, and the tear strength and tensile strength may decrease. On the other hand, if the amount is too large, the fatigue property may decrease.

  The carboxyl group-containing nitrile rubber is usually a diene unit because the cross-linked product has rubber elasticity in addition to the above α, β-ethylenically unsaturated nitrile unit and α, β-ethylenically unsaturated carboxylic acid unit. And / or also having α-olefin units.

  Examples of the diene constituting the diene unit include conjugated dienes having 4 or more carbon atoms such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene; 1,4-pentadiene Preferably, non-conjugated dienes having 5 to 12 carbon atoms such as 1,4-hexadiene are used. Among these, conjugated dienes are preferable, and 1,3-butadiene is more preferable. The α-olefin constituting the α-olefin unit is preferably one having 2 to 12 carbon atoms, such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like. Is mentioned. The content of diene units and / or α-olefin units is preferably 25 to 85% by weight, more preferably 35 to 80% by weight, and still more preferably 45 to 75% by weight. If the content of the diene unit or α-olefin unit is too small, the rubber elasticity may be lowered in the case of a crosslinked product, and if too large, the heat resistance and chemical stability may be impaired.

  The carboxyl group-containing nitrile rubber may have other monomer units copolymerizable with the above monomers. Examples of such other monomers include α, β-ethylenically unsaturated dicarboxylic acid monoesters other than α, β-ethylenically unsaturated dicarboxylic acid monoesters, aromatic vinyls, fluorine-containing vinyls, α, β-ethylenes. Unsaturated polyvalent carboxylic acid anhydride, copolymerizable anti-aging agent and the like. The content of these other monomer units is preferably 80% by weight or less, more preferably 50% by weight or less, and still more preferably 10% by weight or less.

The carboxyl group content in the carboxyl group-containing nitrile rubber according to the present invention is the number of carboxyl groups per 100 g of the carboxyl group-containing nitrile rubber, preferably 5 × 10 ^{−4 to} 5 × 10 ⁻¹ ephr, more preferably 1 × 10. ⁻³ to 1 × 10 ⁻¹ ephr, more preferably 5 × 10 ^{−3 to} 6 × 10 ⁻² ephr. If the carboxyl group content is too small, crosslinking in the case of a crosslinked product may be insufficient, and the tear strength and tensile strength may decrease. On the other hand, if the amount is too large, the fatigue property may decrease.

The carboxyl group-containing nitrile rubber according to the present invention has a Mooney viscosity [ML _{1 + 4} , 100 ° C.] of preferably 15 to 200, more preferably 30 to 100, and still more preferably 45 to 90.

  The latex of the carboxyl group-containing nitrile rubber according to the present invention can be prepared, for example, by copolymerizing the above monomers by an emulsion polymerization method using a polymerization tank or the like. If necessary, the copolymer is obtained so that the copolymer has an iodine value of 120 or less, more preferably 80 or less, still more preferably 50 or less, and particularly preferably 25 or less. The polymer may be hydrogenated (hydrogenation reaction).

Method for Producing Carboxyl Group-Containing Nitrile Rubber The method for producing a carboxyl group-containing nitrile rubber of the present invention supplies the carboxyl group-containing nitrile rubber latex and a coagulating liquid containing a coagulant to a pump with a crushing function, A method for producing a carboxyl group-containing nitrile rubber comprising a step of solidifying a carboxyl group-containing nitrile rubber component by contacting latex and the coagulant to obtain a crumb slurry containing a crumb-like carboxyl group-containing nitrile rubber. ,
The carboxyl group-containing nitrile rubber component is coagulated at a temperature of 40 ° C. or higher.

  Here, as a pump with a crushing function, the carboxyl group-containing nitrile rubber can be solidified by bringing the carboxyl group-containing nitrile rubber latex into contact with the coagulating liquid, and the resulting crumb slurry can be crushed. Any pump may be used. Moreover, as a pump with a crushing function, what is equipped with the rotary blade which has a function which discharges the obtained crumb slurry to the pump exterior is preferable. More specifically, blade pumps equipped with rotating blades, bladeless pumps such as homogenizers and high shear mixers, and the like can be used. The rotary blade may have a function of crushing the crumb slurry, but a bladed pump having a rotary blade is preferable from the viewpoint of productivity, crumb dispersibility, and the like. The pump with a blade having a rotary blade is not particularly limited, but what is called a crushing pump is preferable.

  Next, a method for producing a carboxyl group-containing nitrile rubber from the carboxyl group-containing nitrile rubber latex will be described. FIG. 1 is a schematic view of a production apparatus used in a method for producing a carboxyl group-containing nitrile rubber according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a main part of a pump with a crushing function according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS These are the schematic diagrams which show a part of manufacturing apparatus used for the manufacturing method of the carboxyl group-containing nitrile rubber which concerns on one Embodiment of this invention.

  As shown in FIG. 1, the apparatus for producing a carboxyl group-containing nitrile rubber according to an embodiment of the present invention includes a pump 10 with a crushing function, a stirring device 12, a rotary screen 14, and a squeezer 16.

  As shown in FIG. 2, in the pump 10 with the crushing function, a circular rotating body 30 having a first blade 32 and a second blade 34 is rotatable in a pump casing 24 having a suction port 26 and a discharge port 28. It has a configuration attached to. The rotating body 30 is rotationally driven together with the first blade 32 and the second blade 34 by a motor (not shown) connected to the rotating shaft 36. Further, a stator (fixed frame) 38 is disposed between the first blade 32 and the second blade 34 so as to cover the first blade 32.

  A plurality of the first blades 32 and the second blades 34 are provided on the rotating body 30, and rotate together with the rotating body 30 to suck fluid from the suction port 26 and crush and disperse crumbs contained in the fluid. The crushed crumb can be discharged from the discharge port 28 together with the fluid.

  The first blade 32 is a rotary blade for crushing crumbs contained in the fluid sucked from the suction port 26. The first blade 32 only needs to have a structure capable of pulverizing the crumb. Preferably, the shear rate (share rate) applied to the crushed crumb is 200 [1 / s] or more. To do. The upper limit of the shear rate is preferably 2000 [1 / s] or less.

  The second blade 34 is a rotary blade for dispersing and discharging the crumb crushed by the first blade 32. The second blade 34 may have a structure that can disperse and discharge the crushed crumb, and is not particularly limited, but crumbs are clogged in the gap between the stator 38 and the pump casing 24. It is preferable that the structure does not occur. That is, it is preferable that the second blades 34 have a structure that allows the crumbs discharged between the stator 38 and the pump casing 24 to be almost completely dispersed by rotating the outer periphery of the stator 38.

  In the present embodiment, since the second blade is formed on the outer peripheral side of the first blade together with the first blade 32, the discharge head of the pump is preferably increased to 10 m or more, more preferably 12 m or more. it can. The upper limit of the pump discharge head is preferably 100 m or less. Therefore, it is possible to effectively prevent clogging of the crumb inside the pump. In particular, in the present embodiment, since the second blades 34 are provided on the outer periphery of the stator 38, it is possible to effectively prevent crumb clogging in the gap between the stator 38 and the pump casing 24.

The stator 38 is disposed between the first blade 32 and the second blade 34 so as to cover the first blade 32. The stator 38 has a suction hole 38a on the suction port 26 side and a side surface portion. A through hole 38b is provided. The suction hole 38 a is a through hole for sending the fluid sucked from the suction hole 26 toward the first blade 32. On the other hand, the through hole 38b is a through hole for discharging the crumbs crushed by the first blade 32 and having a size of a certain size or less from the first blade 32 toward the second blade 34. By adjusting the size, the size of the crumb discharged can be controlled. The shape and size of the through-hole 38b are not particularly limited, but it is preferable to adjust the maximum width of the crumbs crushed by the first blade 32 and discharged in the direction of the second blade 34 to 3 to 20 mm. . If the through-hole 38b is too small, the time required for crushing the crumb becomes longer, and the productivity tends to decrease. On the other hand, if it is too large, the crumb may be clogged in the pump 10.
In addition, since the effect of the present invention becomes more remarkable, the specific power when coagulating using a pump with a crushing function (power consumed by a pump with a crushing function / carboxyl group-containing nitrile present in the pump during coagulation) The weight of rubber) is preferably 0.01 to 1 kwh / kg, particularly preferably 0.03 to 0.1 kwh / kg.

  An adapter 40 is attached to the suction port 26. The adapter 40 has a latex transport pipe 42 serving as a latex feed means for feeding a latex of a carboxyl group-containing nitrile rubber in a solution state, and a coagulation liquid transport pipe 44 serving as a coagulation liquid feed means for feeding a coagulation liquid containing a coagulant. And formed.

  The coagulation liquid transported by the coagulation liquid transport pipe 44 is a mixed liquid of a coagulant and water. The coagulant is not particularly limited. For example, inorganic acids such as sulfuric acid and hydrochloric acid; organic acids such as acetic acid; inorganic salts such as calcium chloride, magnesium chloride, sodium chloride, magnesium sulfate, aluminum sulfate, and barium chloride; Although a mixture etc. are mentioned, What is necessary is just to determine suitably by the kind etc. of the emulsifier currently used for polymer latex. Among these, inorganic salts are preferable. The coagulant concentration in the coagulation liquid is preferably 1 to 30% by weight.

  The adapter 40 is brought into contact before the latex of the carboxyl group-containing nitrile rubber and the coagulating liquid sent by the latex transporting pipe 42 and the coagulating liquid transporting pipe 44 are mixed by the first blade 32 and the second blade 34, respectively. As shown, it is inserted into the suction port 26. The solid content concentration of the carboxyl group-containing nitrile rubber latex is preferably 2 to 50% by weight, particularly preferably 3 to 30% by weight.

In the present embodiment, the carboxyl group-containing nitrile rubber latex and the coagulating liquid are separately supplied from the suction port 26 via the latex transporting pipe 42 and the coagulating liquid transporting pipe 44, respectively, in the flow direction of the first blade 32. The carboxyl group-containing nitrile rubber is coagulated in the vicinity of the first blade 32 by bringing the carboxyl group-containing nitrile rubber latex into contact with the coagulating liquid before the first blade 32 in the flow direction. Then, the solidified carboxyl group-containing nitrile rubber is crushed and dispersed by the first blade 32 and the second blade 34, and a slurry containing crumbs of carboxyl group-containing nitrile rubber having an appropriate size to be transported (crumb slurry). And discharged from the discharge port 28.
The crumb concentration (solid content concentration) in the crumb slurry is preferably 1 to 40% by weight, particularly preferably 2 to 20% by weight.

  Here, in this embodiment, the temperature at which the latex of the carboxyl group-containing nitrile rubber is brought into contact with the coagulation liquid to coagulate the carboxyl group-containing nitrile rubber is 40 ° C. or higher, preferably 50 to 70 ° C., more preferably. Set to 54 to 65 ° C. By controlling the temperature at the time of solidifying the carboxyl group-containing nitrile rubber within the above range, the carboxyl group-containing nitrile rubber as the rubber-like polymer can be solidified by the crushing function pump 10 satisfactorily. You can get a good crumb. On the other hand, if the temperature at the time of solidifying the carboxyl group-containing nitrile rubber is less than the above range, solidification failure occurs, the resulting crumb is highly sticky, moisture is taken into the crumb, The crumbs will be attached to each other. As a result, when the crumb slurry is stirred and retained by the high shear mixer 12 described later, the crumbs adhere to each other in the tank 18 or when the rotary screen 14 is washed, the screen is clogged. Occur. Moreover, when temperature is too high, a crumb will become small and there exists a possibility that a crumb may escape from the squeezer 16 mentioned later.

  The method for controlling the temperature at which the carboxyl group-containing nitrile rubber is coagulated is not particularly limited, but the carboxyl group-containing nitrile rubber latex and the latex when the carboxyl group-containing nitrile rubber latex is brought into contact with the coagulation liquid and What is necessary is just to adjust so that the temperature of coagulation liquid may become the said range. Specific methods for controlling the temperature at the time of solidification include, for example, a method of adjusting the internal temperature of the pump 10 with a crushing function in which solidification is actually performed using a heating means, as well as the carboxyl group-containing nitrile rubber. Examples thereof include a method of supplying the latex and the coagulation liquid to the pump 10 with a crushing function in a state where the temperatures of the latex and the coagulating liquid are adjusted in the above range in advance. The temperature of the carboxyl group-containing nitrile rubber latex and coagulation liquid can be adjusted in the above range in advance by adding them in the raw material tank before being supplied to the latex transport pipe 42 and the coagulation liquid transport pipe 44. Examples thereof include a method of heating, a method of heating the latex transport pipe 42 and the coagulating liquid transport pipe 44, and adjusting the temperature to be within the above range while passing through these. These methods may be combined as appropriate.

  In the present embodiment, the concentration of the coagulant when coagulating the carboxyl group-containing nitrile rubber is preferably 0.1 to 20% by weight relative to the total of all components other than the carboxyl group-containing nitrile rubber. The latex and coagulation liquid of carboxyl group-containing nitrile rubber are supplied so that the amount is preferably 0.2 to 10% by weight, particularly preferably 0.3 to 5% by weight. By setting the concentration of the coagulant in the above range, the effect of the present invention becomes more remarkable. Further, the solidification of the carboxyl group-containing nitrile rubber can be sufficiently advanced, the unsolidified content can be reduced, and the yield can be improved. Since the carboxyl group-containing nitrile rubber latex contains a carboxyl group-containing nitrile rubber and water, and the coagulation liquid contains a coagulant and water, The concentration of the coagulant with respect to the sum of the water in the latex and the coagulant and water in the coagulation liquid may be within the above range. Moreover, what is necessary is just to make the density | concentration of the coagulant | flocculant with respect to what added dilution water to these components other than latex and coagulation liquid, for example, the below-mentioned dilution water is made the said range.

  Furthermore, in this embodiment, in addition to the polymer latex and the coagulation liquid, dilution water can be used as necessary. As the dilution water, overflow water from the tank 18 described later, It is preferable to use the recovered washing waste water. The dilution water is put into the pump 10 with a crushing function in a state of being mixed with latex of carboxyl group-containing nitrile rubber or coagulating liquid in advance. In addition, even when diluting water is used, the temperature at which the carboxyl group-containing nitrile rubber is solidified may be adjusted to be in the above range.

  As shown in FIGS. 2 and 3, the pump 10 has a discharge port 28 for discharging the crumb slurry upward. The inner diameter (diameter) D of the discharge port 28 is preferably 50 to 200 mm. As shown in FIG. 3, a slurry supply pipe 46 is connected to the discharge port 28, and the crumb slurry discharged from the discharge port 28 is once released into the atmosphere through the slurry supply pipe 46. Then, the slurry is caused to collide with a side wall 48 formed at a connection portion between the slurry supply pipe 46 and the stirring device 12, is dropped, and is supplied into the tank 18. The slurry supply pipe 46 has a pipe length L that is the length from the discharge port 28 of the pump 10 to the open portion, and this pipe length L is the sum of L1 and L2 shown in FIG. L = L1 + L2), and L = about 200 to 2000 mm. However, depending on the arrangement, such as when the pump can be installed sideways, or when the discharge port of the pump is previously installed in the pump casing lateral direction / lateral tangential direction, the pipe length L is 0, i.e. The pump discharge port may be directly connected to the stirring device 12 without being interposed. Further, the length ratio between L1 and L2 in FIG. 3 is not particularly limited, and can be appropriately adjusted according to the installation space of the equipment.

  In the present embodiment, the ratio (L / D) between the inner diameter D of the discharge port 28 and the length L of the slurry supply pipe 46 is preferably 20 or less, more preferably 18 or less. By setting the ratio (L / D) of the inner diameter D of the discharge port 28 to the length L of the slurry supply pipe 46 within the above range, clogging of the crumb in the pipe 46 can be effectively prevented, As a result, the dispersibility of the crumb in the slurry at the time of opening can be improved.

Next, the crumb slurry released from the slurry supply pipe 46 to the atmosphere is stirred and retained by the high shear mixer 12. As shown in FIG. 3, the high shear mixer 12 includes a tank 18 and a stirrer 20 provided with a rotary blade and a fixed blade at the bottom of the tank 18, and a rotary blade ( With the stirring effect (not shown), the slurry is stirred and retained by generating a circulating flow in the slurry. By stirring and retaining the crumb slurry using the high shear mixer 12, the adhesion of the coagulant to the carboxyl group-containing nitrile rubber component is promoted, and the coagulation of the carboxyl group-containing nitrile rubber component is almost completely advanced. be able to. In addition, it is preferable that stirring and residence of a crumb slurry shall be about 1 to 20 minutes. Further, as the stirrer 20, from the viewpoint of promoting the contact of the coagulant with the carboxyl group-containing nitrile rubber component, the stirring power (the value obtained by dividing the power consumed for stirring by the volume of the crumb slurry) is: Preferably it is 1 kW / m ³ or more, more preferably 2 kW / m ³ or more, more preferably 5 kW / m ³ or more, and particularly preferably 15 kW / m ³ or more. By stirring and retaining the crumb slurry using a high shear mixer, the coagulant can be efficiently attached to the carboxyl group-containing nitrile rubber component in the crumb slurry, and stirring and retention can be performed in a short time. Thus, the solidification of the carboxyl group-containing nitrile rubber component in the crumb slurry can proceed almost completely.
The crumb concentration (solid content concentration) in the crumb slurry is preferably 1 to 40% by weight, particularly preferably 2 to 20% by weight.
Moreover, as for the temperature at the time of the said stirring and residence, 10-50 degreeC is preferable.

  Next, the crumb slurry is washed using the rotary screen 14, the coagulant adhering to the surface of the crumb-like carboxyl group-containing nitrile rubber is removed, and water and the crumb-like carboxyl group-containing nitrile rubber are separated, Obtain a wet crumb.

  Cleaning of the crumb slurry is performed by feeding cleaning water into the rotary screen 14 and rotating the screen. The cleaning reduces the coagulant concentration to about 1000 ppm or less. The amount of water used for washing is preferably about 1 to 10 times by weight with respect to the carboxyl group-containing nitrile rubber component.

  In addition, it is preferable to collect | recover about the washing | cleaning waste_water | drain with comparatively low coagulant | flocculant density | concentration among washing | cleaning waste_water | drain generate | occur | produced by a washing | cleaning process, and to inject into the pump 10 with a crushing function again as dilution water.

  Subsequently, the squeezer 16 is used to dehydrate the washed hydrated crumb. The squeezer 16 has a rotatable screw 22 inside, and dewatering is performed by squeezing out moisture from the crumb, thereby obtaining a crumb whose water content is adjusted to about 10% by weight.

  Next, the dehydrated crumb is heat-dried by a band dryer to obtain a crumb that is substantially free of moisture (moisture content is 0.5% by weight or less). The temperature at which the crumb is dried is about 40 to 100 ° C.

  Next, the dried crumb is discharged, for example, in the form of flakes, then introduced into a baler (not shown), compressed, made into an appropriate size and made into a product (bale).

  In the method for producing a carboxyl group-containing nitrile rubber according to the present embodiment, the coagulation apparatus comprising a large tank that has been conventionally used is obtained by coagulating the rubbery polymer component using the pump 10 having a crushing function. Since it becomes unnecessary, the manufacturing process and equipment can be reduced, and the equipment cost and the manufacturing cost can be reduced. In this embodiment, the rubbery polymer component can be coagulated at a high crumb concentration, so that the amount of washing water and coagulant used can be reduced. Further, the operation is simplified, the loss of the product is reduced even when the type of the rubbery polymer to be produced is switched, and the switching time can be shortened, so that the operability is improved.

  Moreover, in the present embodiment, the carboxyl group-containing nitrile rubber can be solidified satisfactorily and sufficiently by solidifying the carboxyl group-containing nitrile rubber with the crushing function pump 10 at a temperature of 40 ° C. or higher. . As a result, it is possible to obtain a crumb of carboxyl group-containing nitrile rubber in which almost no moisture is taken into the crumb, the tackiness is low, and the crumbs are not attached to each other.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

  For example, in the above-described embodiment, a method for producing a rubber-like polymer including a step of stirring and retaining a crumb slurry obtained by coagulating a rubber-like polymer component with the crushing function pump 10 using a high shear mixer 12. However, it is also possible to employ a process in which the crumb slurry is charged into the rotary screen without passing through the stirring / retaining process.

  Further, in the above-described embodiment, the method in which the carboxyl group-containing nitrile rubber latex and the coagulation liquid are separately fed into the pump 10 with a crushing function is illustrated. Can be mixed into the pump 10 with a crushing function in a state of being mixed in advance, or can be mixed immediately before being put into the pump 10 with a crushing function and then put into the pump 10 with a crushing function.

  Further, in the above-described embodiment, the crumb slurry is cleaned using the rotary screen 14, but the crumb slurry can also be cleaned using a wedge-type screen.

  Hereinafter, the present invention will be described based on more specific examples, but the present invention is not limited to these examples.

Example 1
First, sodium dodecylbenzenesulfonate, acrylonitrile, mono-n-butyl maleate and t-dodecyl mercaptan were charged in this order in ion-exchanged water, and the internal gas was purged with nitrogen, and then 1,3-butadiene and cumene hydroperoxide were added. After emulsion polymerization at 5 ° C., latex of carboxyl group-containing nitrile rubber obtained by hydrogenating the double bond of the polymer using a palladium catalyst (acrylonitrile unit: 34% by weight, butadiene unit: 59% by weight) And n-monobutyl maleate unit: 7% by weight, iodine value: 10, solid content concentration: 10.8% by weight), and magnesium sulfate aqueous solution (coagulant concentration: 7.5% by weight) as a coagulating liquid . The ML _{1 + 4} (100 ° C.) of the carboxyl group-containing nitrile rubber obtained after coagulation and drying was 40.

  And the carboxyl group containing nitrile rubber was manufactured using the manufacturing apparatus which has the pump 10 with a crushing function shown in FIGS. 1-3 using the latex of the carboxyl group containing nitrile rubber and magnesium sulfate aqueous solution which were prepared. .

  In the present embodiment, as the pump 10 with the crushing function, a pump in which the second blade 34 is formed on the outer periphery of the first blade 32 as shown in FIG. 2 is used for an Inline Mixer (model 450LS manufactured by Silverson). . Pump rotational speed is 3000 rpm, carboxyl group-containing nitrile rubber latex flow rate is 1861 kg / h (carboxyl group-containing nitrile rubber flow rate 201 kg / h), magnesium sulfate aqueous solution flow rate is 1138 kg / h (magnesium sulfate flow rate 20 kg / h, In this case, 267 kg / h of diluting water is mixed with 267 kg / h of magnesium sulfate solution with a coagulant concentration of 7.5% by weight prepared above), and the crumb concentration in the crumb slurry discharged from the pump 10 with the crushing function is 6 0.71% by weight of magnesium sulfate concentration [weight of magnesium sulfate / (weight of water in latex + weight of magnesium sulfate aqueous solution after mixing with dilution water)] in the pump 10 with a crushing function is 0.71% by weight did. Moreover, the discharge head of the pump 10 with a crushing function was 20 m, and the specific power of the pump 10 with a crushing function during solidification was 0.038 kwh / kg per weight of the carboxyl group-containing nitrile rubber.

  Further, in this embodiment, the temperature of the latex of the carboxyl group-containing nitrile rubber to be supplied and the magnesium sulfate aqueous solution and the temperature in the pump 10 with a crushing function are adjusted so that the coagulation temperature of the carboxyl group-containing nitrile rubber becomes 55 ° C. did.

  In this example, when the carboxyl group-containing nitrile rubber was manufactured under the above conditions, the state of the crumb after being discharged from the pump 10 with a crushing function, the amount of serum in the serum after being discharged from the pump 10 with a crushing function The amount of uncoagulated components was measured according to the following method.

Using a screen, the crumb of the nitrile rubber containing carboxyl groups is taken out from the crumb slurry discharged from the pump 10 with a crumb state crushing function , and the state of the crumb after solidification is evaluated by visually observing the taken out crumb. did. The evaluation criteria were as follows. The results are shown in Table 1.
◎… Almost no moisture is taken into the crumb and the adhesiveness is low.
○… Some moisture is taken into the crumb and is slightly sticky.
×: Moisture is taken into the crumbs, and the crumbs adhere to each other in a highly sticky state.

By collecting serum water from the crumb slurry discharged from the pump 10 with the crushing function of the amount of uncoagulated components, filtering and drying the uncoagulated components in the collected serum water with a filter paper, and measuring the weight, The content ratio (% by weight) of the uncoagulated component in the serum water to the serum water was measured. The results are shown in Table 1. In Table 1, “> 1” indicates that it is more than 1% by weight.

Examples 2 and 3, Comparative Examples 1 and 2
Example 1 except that the solid content concentration of the carboxyl group-containing nitrile rubber latex used, the carboxyl group-containing nitrile rubber latex flow rate, the magnesium sulfate aqueous solution flow rate, and the coagulation temperature were changed as shown in Table 1. Then, a carboxyl group-containing nitrile rubber was produced and evaluated in the same manner as in Example 1. In addition, the specific power of the pump 10 with a crushing function per weight of the carboxyl group-containing nitrile rubber was 0.038 kwh / kg in Examples 2 and 3, and 0.023 kwh / kg in Comparative Example 1.

As shown in Table 1, coagulation of the carboxyl group-containing nitrile rubber is performed using the pump 10 with a crushing function, and the crumb of the carboxyl group-containing nitrile rubber obtained is excellent by setting the coagulation temperature to 40 ° C. or higher. (Examples 1-3). In Examples 1 to 3, the crumbs are not attached to each other in the tank 18 of the high shear mixer 12 shown in FIG. 1 and the screen 14 is not clogged. Could be done.
In particular, in addition to setting the solidification temperature to 40 ° C. or higher, preferably 50 to 70 ° C., by controlling the magnesium sulfate concentration during solidification to a specific range, it is possible to obtain a better crumb with lower tackiness. In addition, the amount of uncoagulated components remaining in the serum water can be further reduced (Examples 1 to 3).

  On the other hand, when the carboxyl group-containing nitrile rubber is solidified at a temperature of less than 40 ° C., the carboxyl group-containing nitrile rubber is insufficiently solidified, and the resulting crumb has moisture in the crumb. As a result, the crumbs were attached to each other in a highly adhesive state (Comparative Examples 1 and 2). In Comparative Example 1, since the obtained crumb contains a lot of moisture inside and has high adhesiveness, the load on the motor during coagulation by the pump 10 is reduced, and as a result, the pump 10 The specific power was lower than the specific power of the pumps 10 of Examples 1 to 3. Further, in Comparative Examples 1 and 2, crumbs were attached together and the screen 14 was clogged in the tank 18 of the high shear mixer 12 shown in FIG.

FIG. 1 is a schematic view of a production apparatus used in a method for producing a carboxyl group-containing nitrile rubber according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a main part of a pump with a crushing function according to an embodiment of the present invention. FIG. 3 is a schematic view showing a part of a production apparatus used in the method for producing a carboxyl group-containing nitrile rubber according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Pump with crushing function 12 ... High shear mixer 14 ... Rotary screen 16 ... Squeezer 18 ... Tank 20 ... Stirrer 22 ... Screw 24 ... Pump casing 26 ... Suction port 28 ... Discharge port 30 ... Rotating body 32 ... First blade 34 ... 2nd blade 36 ... Rotating shaft 38 ... Stator 40 ... Adapter 42 ... Latex transport pipe 44 ... Coagulated liquid transport pipe 46 ... Slurry supply pipe 48 ... Side wall

Claims (2)

The carboxyl group-containing nitrile rubber component is coagulated by supplying the latex of the carboxyl group-containing nitrile rubber and the coagulation liquid containing the coagulant to a pump having a crushing function and bringing the latex into contact with the coagulant. A method for producing a carboxyl group-containing nitrile rubber comprising a step of obtaining a crumb slurry containing a crumb-like carboxyl group-containing nitrile rubber,
A method for producing a carboxyl group-containing nitrile rubber, characterized in that the carboxyl group-containing nitrile rubber component is coagulated at a temperature of 40 ° C. or higher.   Containing the carboxyl group such that the concentration of the coagulant when coagulating the carboxyl group-containing nitrile rubber component is 0.1 to 20% by weight with respect to the total of all components other than the carboxyl group-containing nitrile rubber. The method for producing a carboxyl group-containing nitrile rubber according to claim 1, wherein the latex of nitrile rubber and the coagulation liquid are supplied to the pump.

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