JP2005171074A - Production method of isobutylene resin granule - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing isobutylene resin granules by performing granulation while efficiently removing a solvent; and resin granules of isobutylene polymer, especially of an isobutylene copolymer, free from quality degradation and excellent in blocking properties. <P>SOLUTION: In the production method, the resin granules are yielded by a step (1) wherein a surfactant, water, and a silicone oil are added to a solution containing an isobutylene polymer, and then a solvent is removed from the solution by heating while liquid-liquid dispersion is being kept by stirring. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing an isobutylene-based resin particle that is granulated while efficiently removing a solvent, and particularly relates to a method for producing a resin particle comprising an isobutylene-based block copolymer.

  Isobutylene block comprising a polymer block mainly composed of isobutylene and a polymer block mainly composed of aromatic vinyl monomer by cationic polymerization of isobutylene and aromatic vinyl monomer such as styrene. Regarding the method for producing the copolymer, for example, US Pat. No. 4,946,899 (Patent Document 1) discloses a production method in a mixed solvent in which methyl chloride and methylcyclohexane are combined.

  Japanese Patent Publication No. 7-59601 (Patent Document 2) also discloses a process for producing an isobutylene block copolymer comprising an isobutylene polymer block and a styrene polymer block in a mixed solvent comprising methylene chloride and hexane. ing.

  Generally, as a method for recovering a rubber-like polymer, there are many cases in which a method of pelletizing by an underwater cutting method after removing a solvent by a thin film evaporator or an extruder or a method of granulating by steam stripping is adopted.

  The recovery of the granular resin slurry from the rubber-like polymer by the steam stripping method often has a blocking problem because the obtained granular particles are soft and irregular. For the blocking property of the granular material, improvement measures by adding a lubricant are the most common. For thermoplastic resins, Japanese Patent Laid-Open No. 64-26644 (Patent Document 3) discloses ethylene bisamide, sorbitan monostearate, etc. A manufacturing method by adding a lubricant is disclosed. Similarly, Japanese Patent Application Laid-Open No. 4-3000947 (Patent Document 4) and Japanese Patent Application Laid-Open No. 7-3106 (Patent Document 5) also disclose a method of adding a hard emulsion polymerization polymer to a thermoplastic resin. On the other hand, for hydrogenated styrene elastomers, Japanese Patent Application Laid-Open No. 2002-371136 (Patent Document 6) discloses a manufacturing method in which a powdery mineral or organic substance is pulverized after drying in Japanese Patent Application Laid-Open No. 10-330404 (Patent Document 6). In 7), a method of dusting polypropylene fine particles is disclosed.

  The blocking property of the product is the same for the isobutylene block copolymer. When the dry granular resin product is recovered without any surface modifier, blocking in the recovery hopper or blocking in the flexible container occurs, and the product is discharged. Troubles such as inability to occur or clogging troubles occurred in the process until the granular resin slurry was dehydrated and dried. On the other hand, in the lubricant addition method, there is a fear that the transparency of the product may be impaired if sufficient blocking property is maintained, and an effective lubricant addition method has not been established.

In this way, it is hoped to develop a manufacturing process that solves various problems associated with the production of resin granules or resin pellets from isobutylene block copolymers and stably produces products with excellent blocking properties without quality degradation. It was rare.
U.S. Pat. No. 4,946,899 Japanese Patent Publication No. 7-59601 JP-A 64-26644 Japanese Patent Laid-Open No. 4-3000947 Japanese Patent Laid-Open No. 7-3106 JP-A-10-330404 JP 2002-371136 A

  The present invention has been made in view of the above situation, and an object thereof is to provide a method capable of stably producing an isobutylene polymer excellent in blocking properties without deterioration in quality, particularly an isobutylene block copolymer resin granule. Is.

  The present invention is a method for producing a resin granule by removing a solvent from an isobutylene polymer solution, and a solution containing an isobutylene polymer, for example, a solution after completion of polymerization in which a catalyst is deactivated and removed From the step (1), a surfactant, water and silicone oil are added to the solution, and the solvent is removed by heating while being liquid-liquid dispersed by stirring. The present invention relates to a process for producing an isobutylene polymer.

  A preferred embodiment relates to a production method characterized by adding a lubricant in step (1).

  As a preferred embodiment, the present invention relates to a production method characterized in that the emulsifier used in step (1) is a nonionic surfactant having a cloud point not lower than the azeotropic point of the solvent and water.

  As a preferred embodiment, the present invention relates to a production method characterized in that the solvent removal temperature in step (1) is 70 ° C. or higher and lower than 130 ° C.

  As a preferred embodiment, the isobutylene polymer comprises (A) a polymer block mainly composed of isobutylene, and (B) a polymer block mainly composed of an aromatic vinyl monomer. The present invention relates to a production method which is a copolymer.

  In a preferred embodiment, the solvent of the isobutylene polymer solution is a mixed solvent of a primary and / or secondary monohalogenated hydrocarbon having 3 to 8 carbon atoms and an aliphatic and / or aromatic hydrocarbon. It relates to a manufacturing method.

  According to the present invention, the blocking property after drying of the resin particles obtained by removing the solvent from the isobutylene polymer can be improved without quality deterioration.

  The isobutylene polymer of the present invention is not particularly limited as long as it is a polymer containing isobutylene, but (A) a polymer block mainly composed of isobutylene and (B) an aromatic vinyl monomer as a main component. An isobutylene copolymer comprising a polymer block constituted as follows is preferred. Specifically, a monomer such as isobutylene and an aromatic vinyl monomer is cationically polymerized with an initiator in the presence of a Lewis acid catalyst. Can be suitably used.

  The polymer block composed mainly of isobutylene in (A) is usually a polymer block containing 60% by weight or more, preferably 80% by weight or more of isobutylene units. The polymer block mainly composed of the aromatic vinyl monomer (B) is usually a polymer containing 60% by weight or more, preferably 80% by weight or more of an aromatic vinyl monomer unit. It is a block.

  The aromatic vinyl monomer is not particularly limited, and examples thereof include styrene, o-, m- or p-methylstyrene, α-methylstyrene, and indene. These may be used alone or in combination of two or more. Of these, styrene, p-methylstyrene, α-methylstyrene or a mixture thereof is particularly preferable from the viewpoint of cost.

The Lewis acid catalyst in the present invention is not particularly limited as long as it can be used for cationic polymerization, and examples thereof include metal halides such as TiCl ₄ , BCl ₃ , BF ₃ , AlCl ₃ , SnCl ₄ , among others. Titanium tetrachloride (TiCl ₄ ) is preferred.

  The polymerization solvent used in the cationic polymerization is not particularly limited, and a solvent composed of a halogenated hydrocarbon, a non-halogen solvent, or a mixture thereof can be used. Preferably, it is a mixed solvent of primary and / or secondary monohalogenated hydrocarbons having 3 to 8 carbon atoms and aliphatic and / or aromatic hydrocarbons.

  The primary and / or secondary monohalogenated hydrocarbon having 3 to 8 carbon atoms is not particularly limited, and examples thereof include methyl chloride, methylene chloride, 1-chlorobutane and chlorobenzene. Among these, 1-chlorobutane is preferable from the standpoint of the solubility of the isobutylene block copolymer, the ease of detoxification by decomposition, the cost, and the like.

  The aliphatic and / or aromatic hydrocarbons are not particularly limited, and examples thereof include pentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, ethylcyclohexane, and toluene. One or more selected from the group consisting of methylcyclohexane, ethylcyclohexane and toluene are particularly preferred.

  In addition, as an initiator used in cationic polymerization, it is preferable to use a compound represented by the following formula (I).

(CR ¹ R ² X) _n R ³ (I)
[Wherein, X represents a halogen atom, an alkoxy group having 1 to 6 carbon atoms or an acyloxy group. R ¹ and R ² are the same or different and each represents a monovalent hydrocarbon group hydrogen atom or 1 to 6 carbon atoms, R ¹ and R ² may be different even in the same. R ³ represents a polyvalent aromatic hydrocarbon group or a polyvalent aliphatic hydrocarbon group. n shows the natural number of 1-6. ]
Specific examples of the compound of the general formula (I) include 1,4-bis (α-chloro-isopropyl) benzene [C ₆ H ₄ (C (CH ₃ ) ₂ Cl) ₂ ]. , 4-bis (α-chloro-isopropyl) benzene is also called dicumyl chloride].

  In the polymerization of the isobutylene block copolymer, an electron donor component can be further present if necessary. Examples of such compounds include pyridines, amines, amides, sulfoxides, esters, or metal compounds having an oxygen atom bonded to a metal atom.

  In carrying out the actual polymerization, each component is mixed at a temperature of, for example, −100 ° C. or more and less than 0 ° C. under cooling. In order to balance the energy cost and the stability of the polymerization, a particularly preferred temperature range is −80 ° C. to −30 ° C.

  The number average molecular weight of the isobutylene block copolymer is not particularly limited, but is preferably 30,000 to 500,000, particularly preferably 50,000 to 400,000 from the viewpoint of fluidity, workability, physical properties, and the like.

  After the polymerization, the polymer solution containing the isobutylene block copolymer is brought into contact with water or alkaline water to deactivate the catalyst to stop the reaction, followed by washing with water to remove catalyst residues and metal ions. Can be extracted and removed to obtain a purified dope.

  The deactivation and water washing temperatures are not particularly limited, but are preferably in the range of room temperature to 100 ° C. Moreover, the amount of water used for deactivation and washing is not particularly limited, but the volume ratio of water to the polymer solution is preferably in the range of 1/10 to 10.

  The purified polymer solution thus obtained is subsequently subjected to the granulation step (1) (also referred to as a crumbization step). As for the resin concentration in the polymer solution, it is desirable that the solvent used for the polymerization is added if necessary to make it 10 to 60% by weight to form granules. When the dope concentration is low, the concentration can be adjusted to a desired concentration by using one or a plurality of evaporators such as flash evaporation, thin film evaporation, stirring tank, and wet wall type. When the polymer solution concentration is high, it can be adjusted to a desired concentration by diluting the solvent.

  To the purified polymer solution thus obtained, that is, the solution after completion of polymerization containing the isobutylene block copolymer from which the catalyst has been deactivated and removed, a nonionic surfactant, water, and silicone oil are added, The resin particles can be obtained by the step (1) in which the solvent is removed by heating while being liquid-liquid dispersed by stirring. The amount of water to be added is not particularly limited, but it is preferably added in a volume of 0.5 to 4 times the polymer solution from the viewpoint of ease of liquid-liquid dispersion.

  As the nonionic surfactant, it is necessary to stably disperse the polymer solution at a high temperature of 70 ° C. or higher. Therefore, it is preferable to use a nonionic surfactant having a cloud point not lower than the solvent removal temperature. Specific examples include glycerin fatty acid ester, sorbitan ester, propylene glycol fatty acid ester, sucrose fatty acid ester, citric acid mono (di or tri) stearate ester, pentaerythritol fatty acid ester, trimethylolpropane fatty acid ester, polyglycerin fatty acid ester, Polyoxyethylene glycerin fatty acid ester, polyester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol fatty acid ester, polypropylene glycol fatty acid ester, polyoxyethylene glycol fatty alcohol ether, polyoxyethylene alkylphenyl ether, N, N-bis (2-hydroxy Ethylene) fatty amine, condensation product of fatty acid and diethanol, polyoxyethylene and polyoxypropylene Block polymers of emissions, polyethylene glycol, and polypropylene glycol. These may be used singly or in combination of two or more. The amount of the nonionic surfactant to be added is not particularly limited, but is preferably 0.05 to 5 parts by weight with respect to the polymer. If it is 0.05 parts by weight or less, the properties as a surfactant cannot be sufficiently exhibited, and particles are not formed. On the other hand, if the amount exceeds 5 parts by weight, the physical properties of the weight body deteriorate and the problem of foaming in the granulation becomes remarkable, which is not preferable.

  Examples of silicone oils include general dimethylpolysiloxane oils with terminal methyl groups and modified types in which part of the methyl groups are replaced with organic functional groups. Examples of modified types include amino-modified, epoxy-modified, carboxyl Modification, amino / polyether modification and the like. These may be used alone or in combination of two or more. These may be used in an emulsion or may be added as a solution. The amount of silicone oil to be added is not particularly limited, but is preferably 0.01 to 10 parts by weight with respect to the polymer. If it is 0.01 parts by weight or less, the silicone oil does not function sufficiently as an antiblocking agent. Moreover, when it exceeds 10 weight part, the physical-property fall of a weight body will become remarkable and is unpreferable.

  Moreover, in order to further improve the blocking property in the step (1), a lubricant can be used in combination. Examples of the lubricant include a lubricant for imparting lubricity to the resin during resin processing, a release agent for facilitating removal of the molded body from a mold, and the like. Specific examples of the lubricant include calcium carbonate, fatty acid amide, fatty acid ester, metal soap, polyolefin, silica, fluororesin, talc and the like. Among these, one kind or two or more kinds may be combined. These may be used before removing the solvent in step (1), or may be used by a method of adding to the granular slurry after removing the solvent. The amount of lubricant to be added is not particularly limited, but is preferably 0 to 5 parts by weight based on the polymer. When the amount exceeds 5 parts by weight, the physical properties of the weight body are significantly deteriorated.

  Examples of calcium carbonate include light calcium carbonate and calcium bicarbonate having an average particle size of 0.5 to 15 microns, and those obtained by treatment with saturated fatty acids or surfactants, or magnesium or silicates. The thing which mix | blended etc. can be mentioned.

  Examples of fatty acid amides include stearic acid amide, ethylene bis stearic acid amide, erucic acid amide, ethylene biserucic acid amide, oleic acid amide, ethylene bisoleic acid amide, behenic acid amide, ethylene bislauric acid amide, etc. Can do.

  Examples of fatty acid esters include methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl oleate, methyl erucate, methyl behenate, butyl laurate, butyl stearate, isopropyl myristate, isopropyl palmitate Octyl palmitate, octyl stearate and the like.

  Examples of the metal soap include metal soaps using potassium, sodium, aluminum, calcium, zinc, magnesium, barium and the like.

  Examples of polyolefins include powdered polyolefins such as polyethylene, polypropylene, polymethylpentene, and polybutene. At least one selected from these is used. Among these, polypropylene powder can be preferably used.

  Examples of silica include powdery dry silica and wet silica. Among these, hydrophobic anhydrous amorphous silica obtained by reacting the hydroxyl group on the silica surface with monomethyltrichlorosilane or dimethyldichlorosilane is preferable.

  Examples of fluororesins include polytetrafluoroethylene (hereinafter referred to as PTFE), ethylene / tetrafluoroethylene copolymer, polyvinylidene fluoride, tetrafluoroethylene / hexafluoropropylene copolymer, tetrafluoroethylene / hexafluoropropylene / Examples thereof include a vinylidene fluoride copolymer, a tetrafluoroethylene / hexafluoropropylene / perfluoroalkyl vinyl ether copolymer, and polymonochlorotrifluoroethylene. At least one selected from these is used. Among these, PTFE powder is preferably used.

  In the present invention, the refined polymer solution and water are liquid-liquid dispersed in the presence of a nonionic surfactant, and then the step (1) in which the solvent is removed by heating, powders are formed satisfactorily. As a device used for liquid-liquid dispersion by stirring and solvent removal, a container equipped with a stirrer is preferably used. The shape of the stirring blade is not particularly limited, and any blade such as a screw blade, a propeller blade, an anchor blade, a paddle blade, an inclined paddle blade, a turbine blade, and a large lattice blade can be used. In these, liquid-liquid dispersion operation and solvent removal operation can be performed using the same stirring tank, or after the liquid-liquid dispersion operation is performed in advance to form a dispersion liquid, the solvent removal is continuously performed for a plurality of stirring operations. It can also be performed using a tank.

  Although the liquid temperature of a process (1) is not specifically limited, It is preferable that it is more than the azeotropic point of a solvent and water. However, even if it is less than the azeotropic point, the solvent can be easily removed by reducing the pressure in the container. Specifically, it is preferably 70 ° C. or higher and lower than 130 ° C., more preferably 80 ° C. or higher and lower than 110 ° C. When it is 70 ° C. or lower, the solvent removal rate is lowered, which is not preferable in terms of production efficiency. On the other hand, when the temperature is 130 ° C. or higher, the function of the nonionic surfactant is lost and a stable liquid-liquid dispersion cannot be formed.

  The aqueous solution containing the obtained resin granular material can further remove the remaining solvent by passing through the process (2) by the steam stripping operation which continues aeration of steam. The vessel used for steam stripping only needs to be connected to a pipe for introducing steam, and a method of introducing steam into the stirring vessel is preferably used as in the suspension and solvent removal operations. Further, the steam stripping operation can be carried out by venting steam in the same tank following the solvent removal, or can be carried out continuously by providing a separate stripping tank. In addition, as a continuous method, stripping can be performed by connecting one or more aeration and agitation tanks or by bringing steam and resin slurry into contact with each other in a shelf system.

  The aqueous solution containing the resin particles after the steam stripping is dehydrated and dried by the step (3) described below. In order to recover the resin particles from the aqueous solution containing the resin particles, a dehydration operation using various filters, centrifuges, or the like can be used. The moisture content of the resin powder after dehydration by this operation is not particularly limited, but it is effective in terms of energy efficiency in drying or pelletization to be 10 to 50% by weight.

  The obtained water-containing resin granules are dried to produce product granules by using a conductive heat transfer dryer such as a grooved stir dryer or a hot air receiving dryer such as a fluid dryer. Can do. Although the water content in the product granule is not particularly limited, it is preferably less than 1%.

  Moreover, the water-containing resin granular material after dehydration mentioned above or the product granular material after drying can be commercialized as a resin pellet using an extruder having a devolatilization mechanism. As the extruder having a devolatilization mechanism, a single-screw or twin-screw extruder having a vent mechanism can be used. In particular, the twin-screw extruder is preferably used from the viewpoint of solvent removal and monomer removal efficiency. The resin discharged from the extruder can be made into a final product by strand cutting, underwater cutting, hot cutting, or the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited only to these examples.

  The molecular weight and tensile strength of the block copolymer shown in this example were measured by the following methods.

  Molecular weight: GPC system manufactured by Waters (column: Shodex K-804 (polystyrene gel) manufactured by Showa Denko KK, mobile phase: chloroform). The number average molecular weight is expressed in terms of polystyrene.

  About transparency, the 2 mm thickness press sheet was created and transparency was confirmed visually.

  Regarding the blocking property of the obtained resin granules, after drying the resin with a box dryer at 100 ° C., it is filled with 30 g in a cylinder with an inner diameter of 5 cm, and a load of 0.03 MPa is applied with a piston in an 85 ° C. atmosphere. Evaluation was made based on how to loosen by hand after 2 hours of storage.

(Production example)
To a 20 L reaction vessel equipped with a stirrer, 1.70 kg of 1-chlorobutane (dried with molecular sieves), 1.92 kg of hexane (dried with molecular sieves), and 2.90 g of p-dimethyl milk chloride were added. After cooling the reaction vessel to −70 ° C., 2.18 g of N, N-dimethylacetamide and 844 g of isobutylene were added. Further, 85 g of titanium tetrachloride was added to initiate polymerization, and the solution was reacted for 2 hours while stirring the solution at -70 ° C. Next, 408 g of styrene was added to the reaction solution, and the reaction was further continued for 30 minutes to obtain a polymer solution.

  The obtained polymer solution was poured into a large amount of water to stop the reaction. After the reaction was stopped, the polymer solution phase and the aqueous phase were separated with a separatory funnel. The polymer solution phase was washed twice with the same method, and after confirming that the aqueous layer was neutral, the polymer solution phase was discharged to obtain a polymer solution.

  When GPC analysis was performed, the number average molecular weight was 100,000 and the molecular weight distribution was 1.14.

(Example 1)
As shown in FIG. 1, 12.5 liters of pure water and 12.5 liters of the polymer solution obtained in the production example were charged into a pressure-resistant stirring device having a tank volume of 50 liters and an inner diameter of 30 cm, and a nonionic surfactant (polyethylene glycol) 5.1 g of monostearate, 1.6 g of silicone oil (DB-110N manufactured by Dow Corning) (0.224 g of active ingredient) (0.14 parts by weight (0.014 weight of active ingredient) of resin) Part)) was added and sealed. The stirring blade was heated by a jacket while stirring at 400 rpm using a two-stage four-padded paddle with a blade diameter of 15 cm.

  When the temperature in the stirring tank reached 90 ° C., solvent gas was introduced into a condenser attached to the pressure-resistant stirring device, and the solvent was sequentially recovered. The internal pressure was adjusted while paying attention to foaming, and the heating and solvent evaporation were stopped when the internal pressure dropped to normal pressure and the stirring tank internal temperature reached 95 ° C. Stirring was stopped after the internal temperature decreased to room temperature, and the resin slurry produced in the stirring tank was recovered (step (1)). The granular material in the collected resin slurry was good particles having a particle diameter of 1 to 2 mm. The recovered resin slurry was returned to the stirring tank again, sealed and subjected to steam stripping (step (2)). As the stripping conditions, a method of blowing from the lower part of the stirring tank while maintaining 120 ° C. for 60 minutes was adopted.

  This resin slurry was centrifugally dehydrated and dried in a box dryer at 100 ° C. for 2 hours to obtain resin powder particles.

  As shown in Table 1, the obtained resin particles had good blocking properties and good transparency.

(Example 2)
The same procedure as in Example 1 was performed except that 3.3 g (0.2 parts by weight with respect to the resin) of talc was added before dispensing in the step (1).

  As shown in Table 1, the obtained resin particles were further improved in blocking properties and had good transparency.

(Example 3)
The same procedure as in Example 1 was carried out except that 3.3 g of fatty acid amide (0.2 part by weight based on the resin) was added before dispensing in step (1).

  As shown together in Table 1, the obtained resin particles were improved in blocking property to the same level as in Example 2 and also had good transparency.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that silicone oil was not added in step (1).

  As shown in Table 1, the obtained resin particles were poor in blocking properties, and the resins were fused together, and even when loosened by hand, they were not completely loosened.

(Comparative Example 2)
In the same manner as in Example 2, except that the silicone oil was not added in the step (1) and the added talc was changed to 8.2 g (0.5 part by weight based on the resin).

  As shown together in Table 1, the obtained resin particles were not completely improved in blocking properties, and the resins were slightly fused. Moreover, the transparency was also in a tendency to deteriorate.

(Comparative Example 3)
The same procedure as in Example 3 was conducted except that the fatty acid amide added in addition to the fact that the silicone oil was not added in the step (1) was 8.2 g (0.5 part by weight based on the resin).

  As shown together in Table 1, the obtained resin particles were not completely improved in blocking properties, and the resins were slightly fused. Moreover, the transparency was also in a tendency to deteriorate.

It is explanatory drawing of the pressure | voltage resistant stirring apparatus which performs the granulation and steam stripping of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure-resistant stirring tank 2 Raw material preparation line 3, 4 Jacket warm water line 5 Capacitor 6 Solvent recovery line 7 Steam blowing line

Claims (6)

  From the solution containing the isobutylene polymer, a surfactant, water and silicone oil are added to the solution, and the solution is dispersed in a liquid-liquid manner by stirring, and then the solvent is removed by heating to obtain resin granules (1). A method for producing an isobutylene-based resin particle, characterized in that   The method for producing an isobutylene resin granular material according to claim 1, wherein a lubricant is added in the step (1).   The surfactant used in the step (1) is a nonionic surfactant having a cloud point equal to or higher than the azeotropic point of the solvent and water, according to any one of claims 1 and 2. A method for producing isobutylene resin particles.   The method for producing an isobutylene resin granular material according to any one of claims 1 to 3, wherein the solvent removal temperature in the step (1) is 70 ° C or higher and lower than 130 ° C. The isobutylene polymer is
(A) a polymer block composed mainly of isobutylene;
(B) a polymer block composed mainly of an aromatic vinyl monomer,
The method for producing an isobutylene-based resin particle according to any one of claims 1 to 4, wherein the block copolymer is a block copolymer.   The solvent of the isobutylene polymer solution is a mixed solvent of a primary and / or secondary monohalogenated hydrocarbon having 3 to 8 carbon atoms and an aliphatic and / or aromatic hydrocarbon. The manufacturing method of the isobutylene type resin granular material of any one of Claims 1.

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