JP4656965B2 - Method for producing resin powder - Google Patents

Description

  The present invention relates to a method for producing a resin particle, and more particularly to a method for producing a resin particle comprising an isobutylene block copolymer.

  As a method for separating and recovering a resin as a granular material from an aqueous resin granular material solution, generally, there are many cases where a method of removing moisture using various filters or centrifugal dehydrators is employed.

  When the resin is a rubber-like polymer, a problem of blocking often occurs during recovery because the obtained granular material is soft and irregular. Addition of a lubricant is the most common method for improving the blocking property of powders. For thermoplastic resins, JP-A 64-26644 (Patent Document 1) discloses ethylene bisamide, sorbitan monostearate, etc. A method of adding a lubricant is disclosed. Similarly, a method of adding a hard emulsion polymerization polymer to a thermoplastic resin is also disclosed in JP-A-4-3000094 (Patent Document 2) and JP-A-7-3106 (Patent Document 3). For hydrogenated styrene-based elastomers, Japanese Patent Application Laid-Open No. 10-330404 (Patent Document 4) discloses a method of dusting powdery minerals and organic substances after drying, Japanese Patent Application Laid-Open No. 2002-371136 (Patent Document 5). Discloses a method of dusting polypropylene fine particles.

  The blocking property of the product is the same for the isobutylene block copolymer. If the granular resin is recovered without any surface modifier, it will be blocked by the recovery hopper or blocked in the flexible container, and will not be discharged. Or a blockage trouble occurred in the process until the granular resin slurry was dehydrated and dried.

  However, with the lubricant addition method, if sufficient blocking properties are maintained, the transparency of the product may be impaired, and even if ultrafine particles such as silica are added to maintain transparency, the resin surface can be efficiently treated. An effective method for adding a lubricant has not been established.

  For this reason, when producing resin granules, especially when producing resin granules made of isobutylene block copolymers, it is possible to stably produce products with high transparency and high blocking properties without deterioration in quality. Development of a manufacturing process to be produced in the future has been desired.

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

  In view of the above situation, the present invention can stably produce resin granules having excellent blocking properties, in particular, isobutylene block copolymer resin granules, without deterioration in quality and without particularly impairing transparency. It is intended to provide a method.

  The present invention relates to a method for producing a resin particle, characterized in that colloidal silica having a particle size of 0.1 to 0.3 μm is added to an aqueous solution containing a resin particle.

  A preferred embodiment includes a method for producing a resin granular material, characterized in that 0.01 to 5 parts by weight of colloidal silica is added to 100 parts by weight of the polymer in the resin granular material.

  A preferred embodiment includes a method for producing an isobutylene-based resin particle, wherein the polymer is an isobutylene-based polymer.

In a more preferred embodiment, the isobutylene polymer is
(A) a polymer block composed mainly of isobutylene;
(B) a polymer block composed mainly of an aromatic vinyl monomer;
A method for producing a resin granule, which is a block copolymer comprising:

  According to the manufacturing method concerning this invention, blocking property can be improved, without impairing transparency, without deteriorating the quality of a resin granular material.

  The method according to the present invention comprises adding resin to a polymer solution obtained by polymerizing one or more monomer components, and then heating and stirring the solution to granulate the polymer. It can be widely applied to the body manufacturing method. The polymer to which the method according to the present invention is applied is not particularly limited, and can be applied to polymers obtained by various polymerization methods such as cationic polymerization, anionic polymerization, and radical polymerization. In particular, because of its high viscoelasticity, it can be used for isobutylene polymers in which it is difficult to obtain a powder having a good balance between blocking properties and transparency by conventional methods.

  The production method of the isobutylene polymer will be specifically described below.

  The isobutylene polymer is preferably an isobutylene copolymer composed of (A) a polymer block mainly composed of isobutylene and (B) a polymer block mainly composed of an aromatic vinyl monomer. Specifically, those obtained by cationic polymerization of a monomer such as isobutylene and an aromatic vinyl monomer together with an initiator in the presence of a Lewis acid catalyst are preferable.

  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 used in the polymerization 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 , and SnCl _4. Of these, titanium tetrachloride (TiCl ₄ ) is preferable.

  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.

  The polymer solution obtained by polymerizing the monomer components by a predetermined method is deactivated by bringing the catalyst into contact with water or alkaline water to stop the reaction, followed by washing with water to remove catalyst residues and Extract and remove metal ions. Thereby, a refined dope can be obtained.

  The temperature of catalyst deactivation and water washing is not particularly limited, but is preferably in the range of room temperature to 100 ° C. Further, 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). At the time of granulation, the resin concentration in the polymer solution is desirably 10 to 60% by weight by adding a solvent used for polymerization as necessary. 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. Moreover, when the polymer solution concentration is high, it can be adjusted to a desired concentration by diluting with a solvent.

  A step of removing the solvent by heating while adding a surfactant and water to the purified polymer solution thus obtained, that is, deactivating the catalyst and removing the polymer solution, followed by liquid-liquid dispersion by stirring. An aqueous solution containing the resin particles can be obtained by (1). The amount of water to be added is not particularly limited, but is preferably added in a volume of 0.5 to 4 times with respect to the polymer solution from the viewpoint of ease of liquid-liquid dispersion.

  As the surfactant, a nonionic surfactant is preferably used because of its low foaming. Specific examples of the nonionic surfactant 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 amines, condensation products of fatty acids with diethanol, block polymers of polyoxyethylene and polyoxypropylene, polyethylene glycol, and polypropylene glycol. These may be used singly or in combination of two or more. The amount of the 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, when the amount exceeds 5 parts by weight, the problem of foaming at the time of reducing the physical properties of the polymer and making it into particles is not preferable.

  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 inside 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.

  0.1 to 0.3 μm of colloidal silica is added to the aqueous solution containing the obtained resin granules, and heat treatment is performed with stirring. By passing through the steam stripping step (2), the remaining solvent is further removed, and at the same time, the added colloidal silica can be efficiently attached to the surface of the resin powder. Thereby, the blocking property of the granular material after dehydration can be improved, and it becomes possible to perform a good discharge without being blocked by a recovery hopper, piping, or the like. In addition, the dehydrated resin particles are not blocked in the process before drying, and can be stably manufactured without deterioration of the quality of the obtained product, and particularly without losing transparency. In addition, in the case of an isobutylene type block copolymer, in order to make colloidal silica adhere effectively to the resin particle body surface, it is preferable that the heating temperature at the time of a process shall be 70-180 degreeC. When it is 70 ° C. or lower, colloidal silica does not adhere to the resin efficiently, and the blocking effect is not sufficient. When the temperature is 180 ° C. or higher, fusion between the resins becomes remarkable and coarse particles are generated.

  Examples of colloidal silica include a colloidal solution in which silica is dispersed in a solvent. From the viewpoint of handling, the solvent is preferably dispersed in water, and the silica is preferably nearly spherical.

  The amount of colloidal silica added is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the polymer in the resin powder. If it is 0.01 parts by weight or less, the effect as an antiblocking agent is not sufficient. On the other hand, when the amount exceeds 5 parts by weight, the physical properties of the polymer are deteriorated, particularly the mechanical properties such as tensile strength are markedly deteriorated.

  Colloidal silica having a particle size of 0.1 to 0.3 μm is used. When the particle diameter is 0.1 μm or less, the transparency of the resin after drying is good, but the effect of improving the blocking property is insufficient. When the particle size is 0.3 μm or more, the blocking property is sufficiently improved, but the transparency of the resin after drying is impaired.

  The vessel used for the steam stripping step (2) 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 operation. 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 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.

  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.

  For transparency, a 2 mm thick press sheet was prepared and the 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. After storing for 2 hours, it was evaluated based on how it was loosened by hand.

(Production example)
To a 20 L reaction vessel equipped with a stirrer, 1.70 kg of 1-chlorobutane (dried by molecular sieves), 1.92 kg of hexane (dried by 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. Furthermore, 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
A pressure-resistant stirrer having a tank volume of 50 liters and an inner diameter of 30 cm was charged with 12.5 liters of pure water and 12.5 liters of the polymer solution obtained in the production example, and 5.1 g of a surfactant (polyethylene glycol monostearate), 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 is returned to the stirring tank again, and 4 g of colloidal silica (MP-2040, Nissan Chemical Co., Ltd., average particle size of 0.19 μm, active ingredient content of 40%) is 0.1% of the active ingredient relative to the resin. (Part by weight) was added, sealed and steam stripping was performed (step (2)). As the stripping conditions, a method of blowing steam 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)
In step (2), 12 g of colloidal silica (MP-2040, Nissan Chemical Co., Ltd., average particle size of 0.19 μm, active ingredient content of 40%) was added (the amount of active ingredient was 0.3 parts by weight relative to the resin). Except for this, the same procedure as in Example 1 was performed.

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

(Comparative Example 1)
The same procedure as in Example 1 was performed except that colloidal silica was not added in the step (2).

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

(Comparative Example 2)
In step (2), 12 g of colloidal silica having an average particle size of 0.08 μm (Snowtex ZL manufactured by Nissan Chemical Co., Ltd., active ingredient content of 40%) is added (the amount of active ingredient is 0.3 parts by weight relative to the resin). The same operation as in Example 1 was performed except that.

  As shown in Table 1, the resin particles obtained had no problem with the transparency of the resin, but the blocking properties were poor and loosened by hand, but remained partially coarsened.

(Comparative Example 3)
In step (2), 4 g of colloidal silica having an average particle size of 0.45 μm (MP-4540, Nissan Chemical Co., Ltd., active ingredient content: 40%) is added (the amount of active ingredient is 0.1 parts by weight relative to the resin). The same operation as in Example 1 was performed except that.

  As shown in Table 1, the obtained resin particles were improved in blocking properties, but the transparency of the resin was deteriorated.

Claims (1)

When the resin particles are collected from the aqueous solution containing the resin particles, colloidal silica having a particle size of 0.1 to 0.3 μm is added to 0.1 parts by weight with respect to 100 parts by weight of the isobutylene polymer in the resin particles. A method for producing a resin granular material characterized by adding 01 to 5 parts by weight ,
The isobutylene polymer is
(A) a polymer block composed mainly of isobutylene;
(B) a polymer block composed mainly of an aromatic vinyl monomer,
A method for producing a resin particle, which is a block copolymer comprising: