JPH09169816A - Production of epoxidized block copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an epoxidized block copolymer having a low residual organic solvent content. SOLUTION: A block copolymer composed of blocks of a polymer based on a vinylaromatic compound and blocks of a polymer based on a conjugated diene or a hydrogenated product thereof is mixed with an organic solvent to form an organic solvent solution or slurry having a polymer concentration of 5-50wt.%. The unsaturated C-C bonds present in the polymer blocks in the organic solvent solution or slurry are epoxidized with an epoxidizing agent. The obtained epoxidation solution or slurry is subjected to washing with water and/or neutralization to lower the acid value of the solution or slurry to 5mgKOH/g or below. The epoxidation reaction solution or slurry after being subjected to washing with water and/or neutralization is fed into an evaporator to obtain an epoxidized block copolymer having a residual solvent content of 5,000ppm or below and a gel fraction of 5wt.% or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an epoxidized block copolymer which is economical and has a simple residual amount of residual organic solvent. The epoxidized block copolymer obtained in the present invention can be used as a molded article by itself, or a modifier or modification aid of a rubbery polymer or a resinous polymer, an adhesive, a sealant, It is suitable as an asphalt modifier.

[0002]

2. Description of the Related Art A block copolymer composed of a vinyl aromatic hydrocarbon compound and a conjugated diene compound is transparent and has elasticity at room temperature similar to that of vulcanized natural rubber or synthetic rubber without vulcanization. Moreover, since it has the same processability as that of a thermoplastic resin at high temperature, it is widely used in the fields of various modifiers and adhesion. For the purpose of further improving the above performance, an epoxidized block copolymer in which an unsaturated bond derived from a diene block of the block copolymer is epoxidized has already been proposed. Here, the epoxidized block copolymer is first subjected to an epoxidation reaction in an organic solvent, then the epoxidized block copolymer present in the solvent uniformly dissolved or present in a slurry form is separated from the organic solvent,
Manufacture by collecting.

The steam stripping method is well known as a method for separating the epoxidized block copolymer from the organic solvent and recovering it. This is a method of injecting a solution or slurry containing an epoxidized block copolymer into hot water and distilling an organic solvent with steam to precipitate the epoxidized block copolymer in a crumb-like form. It is disclosed in Japanese Patent Publication No. 55-7457, Japanese Patent Publication No. 55-22489 and Japanese Patent Publication No. 58-10411. The obtained crumb-shaped epoxidized block copolymer is generally dehydrated and dried to remove water. Japanese Patent Application Laid-Open No. 59-53504 discloses a method of adding a metal oxide or a metal carbonate to a crumb-like material obtained by the steam stripping method and drying it with a drier.
Japanese Unexamined Patent Publication No. 61-218614 discloses a method in which the water content of a crumb-like material obtained by the steam stripping method is reduced by a dehydrator and the water content is further removed by a twin-screw vent extruder. It is disclosed.

[0004]

However, since the steam stripping method requires many steps such as a step of depositing crumbs, a step of solid-liquid separation, and a step of dehydration / drying, the operation is not easy. . In particular, if an appropriate surfactant is not selected during steam stripping, the deposited crumb may adhere to the inner wall of the steam stripping tank, the stirring blades, and the like in a large amount, which may make the operation impossible. Further, when the deposited crumbs are dehydrated by a dehydrator, it may be difficult to bite into the screw of the dehydrator depending on the shape of the crumbs and the like. In addition, a large amount of steam is needed to remove the solvent.
It is also economically problematic because it requires

On the other hand, in order to solve the problems of the steam stripping method, the solvent is directly removed from the organic solution containing the epoxidized block copolymer by using an evaporator to obtain the epoxidized block copolymer. There is a method of collecting, for example, JP-A-2-187404 and JP-B-5-387.
No. 62 and Japanese Patent Publication No. 7-681. However, the direct solvent removal treatment from the epoxidation reaction solution is superior to the steam stripping method in that it is economical and has a small number of treatment steps. It is extremely difficult to reduce the solvent content. Furthermore, since the epoxidized block copolymer itself has an epoxy group, which is a highly reactive functional group, it may partially gel in the evaporator, and the product properties may be significantly impaired.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that as a method for producing an epoxidized block copolymer, an organic solvent is directly added from an epoxidation reaction solution. It has been found that the object can be achieved by a specific process including a removing process, and the present invention has been completed.

That is, the present invention provides a block copolymer (C) comprising a polymer block (A) mainly containing a vinyl aromatic hydrocarbon compound and a polymer block (B) mainly containing a conjugated diene compound, or a block copolymer thereof. When the hydrogenated product (D) is epoxidized to obtain the epoxidized block copolymer (E), the following steps (1) to (4) are performed. It is provided. (1) Block copolymer (C) or hydrogenated product (D) thereof
Is mixed with an organic solvent to prepare an organic solvent solution or an organic solvent slurry having a polymer concentration of 5 to 50% by weight (hereinafter, simply referred to as "organic solvent solution"). (2) A step of using an epoxidizing agent to epoxidize the unsaturated carbon bond existing in the polymer block (B) in the organic solvent solution or the organic solvent slurry. (3) The acid value of the solution is adjusted to 5 by washing and / or neutralizing the epoxidation reaction solution or slurry (hereinafter simply referred to as “epoxidation reaction solution”) obtained in the above step.
A step of reducing to less than or equal to mgKOH / g. (4) The washed and / or neutralized epoxidation reaction solution is supplied to an evaporator to directly remove the organic solvent by evaporation,
A step of obtaining an epoxidized block copolymer (E) having a residual organic solvent content of 5,000 ppm or less and a gel content of 5% by weight or less. Moreover, the epoxy equivalent of the epoxidized block copolymer (E) is 140 to 2,700, and the method for producing the epoxidized block copolymer is provided. The present invention is described in detail below.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The block copolymer (C) referred to in the present invention means a polymer block (A) containing a vinyl aromatic hydrocarbon compound as a main component and a polymer block containing a conjugated diene compound as a main component ( B) and. Further, the hydrogenated product (D) of the block copolymer means a copolymerized product obtained by partially hydrogenating an unsaturated carbon bond present in the polymer block (B) of the block copolymer (C) by a hydrogenation reaction. Refers to coalescence. Also,
The epoxidized block copolymer (E) referred to in the present invention is
It refers to a polymer obtained by epoxidizing the unsaturated carbon bond present in the copolymer block (B) of the block copolymer (C) or its hydrogenated product (D).

As the vinyl aromatic hydrocarbon compound which can form the block copolymer (C), various alkyl-substituted styrenes such as styrene and α-methylstyrene, alkoxy-substituted styrene, vinylnaphthalene, alkyl-substituted vinylnaphthalene and divinyl are used. Examples thereof include benzene and vinyltoluene. Of these, styrene is preferred. These may be used alone or in combination of two or more.

The conjugated diene compound which can form the block copolymer (C) includes 1,3-butadiene, isoprene, 1,3-pentadiene and 2,3-dimethyl-1,3.
-Butadiene, piperylene, 3-butyl-1,3-octadiene, phenyl-1,3-butadiene and the like. Among these, 1,3-butadiene and isoprene are preferable because they are inexpensive and easily available. These may be used alone or in combination of two or more.

The copolymerization composition ratio (vinyl aromatic hydrocarbon compound / conjugated diene compound (weight ratio)) of the vinyl aromatic hydrocarbon compound and the conjugated diene compound which can form the block copolymer (C) is preferably It is 5/95 to 70/30, and more preferably 10/90 to 60/40. The number average molecular weight of the block copolymer (C) usable in the present invention is preferably 5,000 to 500,000, more preferably 10,000 to 100,000.
It is. When the molecular weight is lower than 5,000, the properties of the rubber-like elastic body are difficult to be exhibited, and when the molecular weight is high, it is difficult to melt, which is not preferable. Here, the number average molecular weight means GP
The standard polystyrene equivalent molecular weight measured by the C method is meant.

The structure of the block copolymer (C) is not particularly limited. For example, A-B-A, B-A-B
It may be a block copolymer of a vinyl aromatic hydrocarbon compound represented by -A, ABABA, etc. and a conjugated diene compound. The structure of the molecule itself may be any of linear, branched, radial, etc., and may be any combination thereof. In the block copolymer, the vinyl aromatic hydrocarbon compound may be distributed uniformly or in a taper shape. Further, in the copolymerized portion, a plurality of portions in which the vinyl aromatic hydrocarbon compound is evenly distributed and / or a portion in which the vinyl aromatic hydrocarbon compound is distributed in a tapered shape may coexist.

The method for producing the block copolymer (C) before epoxidation is not particularly limited, and any method may be used. For example, Japanese Patent Publication No. 40-23798, Japanese Patent Publication No. 47-3252, and Japanese Patent Publication No. 48-242.
As described in Japanese Patent Publication No. 3 and Japanese Patent Publication No. 56-28925, there can be mentioned a method of producing in an inert solvent using a lithium catalyst or the like.

The method for producing the hydrogenated product (D) of the block copolymer is not particularly limited, and any method may be used. For example, Japanese Patent Publication No. 42-8704
As described in JP-B No. 43-6636 and JP-B No. 43-6636, a method of hydrogenating the block copolymer (C) in the presence of a hydrogenation catalyst in an inert solvent can be exemplified. Although the amount of hydrogenation is not particularly limited, it is necessary that an unsaturated carbon bond capable of reacting with the epoxidizing agent remains in the molecule of the hydrogenated product (D) during the subsequent epoxidation reaction. In the epoxidation, the block copolymer (C) or the hydrogenated product (D) thereof is dissolved or slurried in an appropriate organic solvent and then epoxidized. The site to be epoxidized by the epoxidizing agent is an unsaturated bond present in the polymer block (B).

In the present invention, the block copolymer (C) or its hydrogenated product (D) produced as described above is subjected to the following first to fourth steps to produce an epoxidized block copolymer. . The first step of the present invention is a step of mixing the block copolymer (C) or its hydrogenated product (D) with an organic solvent to obtain an organic solvent having a polymer concentration of 5 to 50% by weight. Typical examples of organic solvents that can be used include linear and branched hydrocarbons such as pentane, hexane, heptane, and octane, and alkyl-substituted derivatives thereof, cyclopentane, cyclohexane, cycloaliphatic hydrocarbons such as cycloheptane, and Their alkyl-substituted derivatives, benzene,
Examples thereof include aromatic and alkyl-substituted aromatic hydrocarbons such as naphthalene, toluene and xylene, aliphatic carboxylic acid esters such as methyl acetate, ethyl acetate and propyl acetate, and halogenated hydrocarbons such as chloroform. Among these, the block copolymer (C) or its hydrogenated product (D)
It is preferable to use cyclohexane, ethyl acetate, chloroform, toluene, xylene, or hexane from the viewpoint of the solubility of the above and the ease of subsequent solvent recovery.

When the concentration of the block copolymer (C) or its hydrogenated product (D) is lower than 5% by weight, a large amount of solvent is used, which is not economical. Further, when it is higher than 50% by weight, the solution viscosity is high, so that the epoxidizing agent is not sufficiently mixed with the organic solution or the slurry in the second step, and it is difficult to remove the reaction heat. Not desirable for reasons.

The second step of the present invention is a step of using an epoxidizing agent to epoxidize the unsaturated bond existing in the polymer block (B) in the organic solvent solution. The epoxidation of the block copolymer (C) or its hydrogenated product (D) can be carried out by reaction with an organic peracid or the like. The epoxidizing agent that can be used in the epoxidation reaction, peracetic acid,
Examples thereof include organic peracids such as perbenzoic acid, formic acid, and trifluoroperacetic acid, hydrogen peroxide, and combinations of hydrogen peroxide and low-molecular fatty acids. Of these, peracetic acid, which is industrially produced in large quantities and can be obtained at a low cost and has a relatively high stability, is preferable as the epoxidizing agent. In addition, a catalyst may be used in the epoxidation, if necessary.

The amount of the epoxidizing agent used is not particularly limited, and the reactivity of the epoxidizing agent used, the desired degree of epoxidation, the amount of the epoxidizing agent used, the amount of the epoxidizing agent used in the block copolymer or the hydrogenated product thereof, and Although an appropriate amount can be arbitrarily used depending on conditions such as the saturated carbon bond amount, the epoxy equivalent of the finally obtained epoxidized block copolymer (E) is from 140 to
It is preferred to choose the amount of epoxidizing agent to be 2,700. The epoxy equivalent is more preferably 200 to
It is 2,000. Here, the epoxy equivalent is calculated by the formula: epoxy equivalent = 1,600 / {oxirane oxygen concentration (wt%) in epoxidized block copolymer}, and weight of epoxidized block copolymer per 1 mol of oxirane oxygen. Indicates. The oxirane oxygen concentration is determined by titrating with an acetic acid solution of hydrogen bromide. When the epoxy equivalent is large, the oxirane oxygen concentration is low, and conversely, when the epoxy equivalent is small, the oxirane oxygen concentration is high. When the epoxy equivalent is smaller than 140, the elastic properties of the polymer are hardly developed, which is not preferable. When it is larger than 2,700, specific physical properties due to epoxidation are hardly formed, which is not preferable.

The epoxidation reaction temperature varies depending on the type and amount of the epoxidizing agent used, the organic solvent used, the block copolymer or its hydrogenated product, and is not particularly limited. For example, the reaction temperature when using peracetic acid as the epoxidizing agent is preferably 0 to 70 ° C.
If the temperature is lower than 0 ° C, the reaction rate is slow, and if the temperature exceeds 70 ° C, the formed epoxy group is opened and the decomposition of peracetic acid proceeds, which is not preferable. To improve the stability of peracetic acid,
Phosphates may be added to the reaction system during the epoxidation reaction. From the viewpoint of productivity, it is preferable to select the epoxidation reaction time in the range of 0.1 to 72 hours, more preferably 0.2 to 10 hours.

The third step of the present invention is a step in which the epoxidation reaction solution is washed with water and / or neutralized to reduce the acid value of the solution to 5 mgKOH / g or less. Here, the acid value is a value obtained by titration of the weight of potassium hydroxide necessary for neutralizing the acids present in 1 g of the reaction crude liquid after the epoxidation reaction. The purpose of washing with water and / or neutralization is to remove by-products such as acids by-produced by the epoxidation reaction carried out in the previous step. If the acid value is higher than 5 mgKOH / g, the epoxy groups present in the epoxidized block copolymer will be ring-opened and the physical properties will be adversely affected.

The washing with water may be carried out continuously or batchwise. In the case of a batch method, it is preferable to wash with 50 to 1,000 parts by weight of water several times with respect to 100 parts by weight of the reaction crude liquid after epoxidation. In particular, when a large amount of epoxidizing agent is used, a corresponding amount of acids is by-produced, so it is preferable to remove the acids by increasing the number of washings with water. During washing with water, an inorganic salt such as sodium chloride or sodium sulfate may be added in order to improve the separation between the aqueous phase and the organic phase.

Typical examples of the alkaline aqueous solution used for neutralization include lithium hydroxide, sodium hydroxide,
Potassium hydroxide, calcium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, calcium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate,
An aqueous solution of sodium acetate, potassium acetate, etc. may be mentioned. The amount of alkali used is preferably a molar amount necessary for neutralizing the acids present in the reaction solution. When the amount of alkali is large, the epoxy ring is opened, which is not preferable. Further, if the amount of alkali is small, the acid remains, and the physical properties are adversely affected by deterioration, which is not preferable. In order to prevent the epoxy group from ring-opening due to the heat generated during neutralization,
It is preferable to neutralize the reaction crude liquid while cooling.

In the fourth step of the present invention, the epoxidation reaction solution containing the epoxidized block copolymer (E) obtained as described above is quantitatively supplied to the evaporator by, for example, a pump, and the reaction is carried out. In this step, the organic solvent is directly evaporated and removed from the solution to recover the epoxidized block copolymer. As the evaporator that can be used in the present invention, a flash tank type evaporator, a stirring tank type evaporator, a thin film evaporator, a wetting wall tower type evaporator, and a vertical type screw capable of multi-stage concentration of one or two or more stages are provided. An evaporator, a vent type extruder, etc. can be illustrated. From the viewpoint of improving production capacity, two or more kinds of evaporators selected from these may be used in combination. Among these, the vent-type extruder is most preferable because it has a high solvent removing ability and a small amount of resin scorching.

The vent type extruder preferably used in the present invention will be described in detail below. The vent type extruder has at least one vent section for degassing, preferably 1 to 10,
Further, it is preferable to have 1 to 5 pieces. It is preferable that the number of shafts is at least one, and particularly two or more. Among these, the twin-screw vent type extruder is versatile and is particularly preferable. As a vent type extruder having such a structure,
L / D = 2 to 50, preferably 4 to 40 (L is the length of the screw, D is the outer diameter of the screw),
The screw engagement structure may be either "meshing" or "non-meshing", and the rotation direction may be the same direction or different directions. Among the twin-screw vent type extruders, those having a structure capable of passing a heat medium inside the screw are particularly preferable. An extruder having such a structure is preferable because it can sufficiently supply a large amount of heat necessary for the organic solvent to evaporate. Further, those having a continuous gas phase part in the upper part of the extruder are preferable because of good solvent removal efficiency.

The temperature inside the evaporator and the pressure inside the evaporator are
Select in consideration of processing capacity, polymer characteristics (viscosity, thermal stability, etc.), solvent type / concentration, product quality, etc. The temperature inside the evaporator is preferably 80 to 300 ° C, more preferably 120 to 250 ° C. The temperature inside the evaporator is 80 ℃
If it is less than 300 ° C., the solvent is not sufficiently removed and the viscosity becomes low. On the other hand, if it is higher than 300 ° C., a large amount of gel is generated in the polymer, which is not preferable. In particular, if the epoxidized block copolymer stays at a high temperature in the evaporator used in the fourth step and a large amount of gel is generated, the melt viscosity is increased, and fish eyes are liable to be formed, which causes molding defects, which is not preferable. The gel content is preferably 5 wt% or less, more preferably 3 wt% or less, and particularly 1 wt%
The following is preferred.

The pressure inside the evaporator is preferably 500 t.
orr or less, and more preferably selected from the range of 400 to 1 torr. The pressure inside the evaporator refers to the pressure at the location showing the lowest pressure in the vapor phase portion in contact with the resin inside the evaporator. In the case of an extruder, it usually means the value read by a pressure gauge attached to the vent. If the pressure inside the evaporator is higher than 500 torr, the solvent is not sufficiently removed, which is not preferable. The screw rotation speed when using a vent type extruder is 20 to 500 rpm,
It is preferably 30 to 400 rpm.

Residual organic solvent in the epoxidized block copolymer finally obtained by removing the organic solvent directly from the epoxidation reaction solution by evaporation through the above steps (hereinafter, also referred to as "direct solvent removal"). Content is 5,000p
pm or less, more preferably 2,000 ppm or less, particularly preferably 1,000 ppm or less, particularly 500 ppm
The following is preferred. Residual organic solvent content is 5,0
If it is more than 00 ppm, it is not preferable since it foams and produces an odor when molded into a product form. The residual organic solvent content can be easily adjusted by changing conditions such as the temperature of the evaporator, the pressure inside the evaporator, and the processing speed.

The epoxidized block copolymer directly desolvated by an evaporator can be selected from any of strands, pellets, foam crumbs, granules and powders, but pellets are preferred.

In the epoxidized block copolymer of the present invention, various additives such as a heat stabilizer, an antiaging agent, a crosslinking agent, an ultraviolet absorber, or silica, talc, carbon, etc. may be added as required. An inorganic filler, a plasticizer, and a softening agent such as oil can be blended and used. The timing of addition of these is not particularly limited and may be any step until finally obtaining the epoxidized block copolymer.

The epoxidized block copolymer obtained by the method of the present invention can be utilized as various molded products such as sheets, films, injection molded products of various shapes, hollow molded products and the like, and various thermoplastic resins can be modified. It is useful as a material for quality agents, adhesives, adhesives, asphalt modifiers, home appliances, automobile parts, industrial parts, household products, toys, and the like.

[0031]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

(Example 1) 300 parts by weight of a polystyrene-polybutadiene-polystyrene block copolymer (SBS, "TR-2000" manufactured by Japan Synthetic Rubber Co., Ltd.) was completely dissolved in 1500 parts by weight of ethyl acetate (No. 1). One step), 169 parts by weight of a 30% ethyl acetate solution of peracetic acid was continuously added dropwise thereto, and an epoxidation reaction was carried out at 40 ° C. for 3 hours with stirring (second step). The reaction liquid was returned to room temperature and washed with pure water to obtain an ethyl acetate solution of an epoxidized polystyrene-polybutadiene-polystyrene copolymer (ESBS) (third step). The concentration of the ethyl acetate solution of this epoxidized block copolymer was 30 wt%. The acid value of this solution was 1.0 mgKOH / g. This solution is capable of passing a heat medium through the inside of the screw, and has a screw outer diameter 4 having a continuous vapor phase portion in the upper part of the extruder.
It was supplied to a twin-screw vent type extruder with 0 mm and L / D = 9, and the solvent was degassed under reduced pressure from the vent part. The vent-type extruder used was operated at a cylinder temperature of 160 ° C., a vent pressure of 100 torr, and a screw rotation speed of 200 rpm. The production rate of the obtained polymer is 10 kg /
The solution was supplied so that it would be h. Next, the polymer discharged from the tip of the extruder was pelletized with a cutter.
The residual solvent content in the polymer after solvent removal was 420 ppm, the gel content was 0.2 wt% or less, and the epoxy equivalent of the polymer was 520. Further, no foaming of the molded product was observed. In the molding, the polymer was pressed at 200 ° C. to obtain a sheet having a thickness of 2 mm, which was visually observed. The results are shown in Table 1.

(Example 2) An ethyl acetate solution (concentration: 30 wt%) of an epoxidized block copolymer obtained by the same method as in Example 1 was mixed with a screw-outer diameter of 40 mm,
Supply to a twin-screw two-stage vent type extruder with L / D = 38.5,
The solvent was degassed under reduced pressure from the vent part. The cylinder temperature of the vent type extruder used was 160 ° C., and the pressure of the vents was 100 torr for both the first and second vents. The screw rotation speed was 200 rpm. Further, the solution was supplied so that the production rate of the obtained polymer would be 10 kg / h. Next, the polymer discharged from the tip of the extruder was pelletized with a cutter. The residual solvent content in the polymer after desolvation is 2,300 ppm, gel content is 0.2 wt%
And the epoxy equivalent of the polymer was 520.
Further, no foaming of the molded product was observed.

EXAMPLE 3 Polystyrene-polybutadiene-in a jacketed reactor equipped with stirrer and thermometer.
Block copolymer of polystyrene (Nippon Synthetic Rubber Co., Ltd.)
(Manufactured by "TR-2000") 300 parts by weight is dissolved in 3000 parts by weight of cyclohexane. As a hydrogenation catalyst, di-
p-Tolylbis (1-cyclopentadienyl) titanium / cyclohexane solution (concentration 1 mmol / liter)
40 g and n-butyllithium solution (concentration 5 mmol /
8 g of liter) was mixed at 0 ° C. under a hydrogen pressure of ² kg / cm ² , and the mixture was added to the above polymer solution and reacted at a hydrogen partial pressure of 2.5 kg / cm ^{2 for} 30 minutes. The solvent was removed from the obtained partially hydrogenated polymer solution by vacuum drying to take out the polymer (the hydrogenation rate of the double bond derived from butadiene was 30%). 300 parts by weight of this partially hydrogenated polymer was dissolved in 1,500 parts by weight of cyclohexane (first step), 300 parts by weight of a 30% ethyl acetate solution of peracetic acid was continuously added dropwise thereto, and the mixture was stirred at 40 ° C. In 3
The epoxidation reaction was performed for a time (second step). The reaction solution was returned to room temperature and washed with pure water to obtain a solution of epoxidized partially hydrogenated polystyrene-polybutadiene-polystyrene copolymer (ESEBS) (third step). The concentration of this block copolymer solution was 22 wt%. The acid value of this solution was 1.3 mgKOH / g. This solution was supplied to the same twin-screw two-stage vent type extruder as in Example 2, and the solvent was degassed under reduced pressure under the same conditions as in Example 2 (fourth step). The polymer discharged from the tip of the extruder was pelletized with a cutter. The amount of residual solvent in the polymer after removing the solvent was 1,500 ppm, the gel content was 0.2 wt% or less, and the epoxy equivalent of the polymer was 285. The results are shown in Table 1.

(Examples 4 to 6) A polystyrene-polybutadiene-polystyrene block copolymer (SBS, "TR-2000" manufactured by Japan Synthetic Rubber Co., Ltd.) was dissolved in ethyl acetate (first step), and peracetic acid was added. Was used for epoxidation reaction (second step). The reaction solution was returned to room temperature, washed with pure water, and the epoxidized polystyrene-polybutadiene-polystyrene polymer (ES having the properties shown in Table 1 was used.
A solution of BS) in ethyl acetate was obtained (3rd step). This solution is capable of passing a heat medium through the inside of the screw, and has a screw outer diameter 40 having a continuous vapor phase portion in the upper part of the extruder.
mm, L / D = 9, and then supplied to a twin-screw vent type extruder.
It was devolatilized under reduced pressure under the conditions shown in 1. The results are shown in Table 1.

Comparative Example 1 A block copolymer was obtained in the same manner as in Example 1 except that the epoxidation reaction crude liquid was not washed with water in the third step of Example 1. The resin obtained had a residual solvent amount of 620 ppm and a gel content of 5.2 wt%. The epoxy equivalent is 540
Met. The results are shown in Table 1.

(Comparative Example 2) A block copolymer was obtained in the same manner as in Example 3, except that the epoxidation reaction crude liquid was not washed with water in the third step of Example 3. The resin obtained had a residual solvent amount of 1,700 ppm and a gel content of 5.3 wt%. The epoxy equivalent is 28
It was 5.

Comparative Example 3 A block copolymer was obtained in the same manner as in Example 1 except that the pressure in the vent section of the extruder was changed to 620 torr in the fourth step of Example 1. The amount of residual solvent of the obtained resin was 9,000 ppm, and it was impossible to mold because a foam was remarkably foamed when the molded body was formed.

Comparative Example 4 A block copolymer was obtained in the same manner as in Example 1 except that the temperature of the extruder was changed to 310 ° C. in the fourth step of Example 1. The residual resin amount of the obtained resin is 50 ppm, and the gel content is 50 wt.
%Met. Therefore, it became impossible to mold.

Comparative Example 5 A polystyrene-polybutadiene-polystyrene block copolymer (SBS, "TR-2000" manufactured by Japan Synthetic Rubber Co., Ltd.) was dissolved in ethyl acetate (first step) and peracetic acid was used. And an epoxidation reaction was performed (second step). The reaction solution is returned to room temperature and washed with pure water to obtain an ethyl acetate solution of epoxidized polystyrene-polybutadiene-polystyrene polymer (ESBS) (concentration 2
wt%) was obtained (third step). The acid value of this solution is 1.
It was 0 mgKOH / g. This solution is capable of passing a heat medium through the inside of the screw and has a continuous vapor phase portion in the upper part of the extruder, the outer diameter of the screw is 40 mm, L / D = 9.
Was supplied to the twin-screw vent type extruder. However, since the viscosity of the solution was low, the solution leaked out from the die hole of the extruder and could not be devolatilized under reduced pressure.

(Comparative Example 6) A polystyrene-polybutadiene-polystyrene block copolymer (SBS, "TR-2000" manufactured by Japan Synthetic Rubber Co., Ltd.) was dissolved in ethyl acetate to obtain a block copolymer concentration of 60 wt%. An organic solvent solution was obtained (first step). Next, an epoxidation reaction was performed using peracetic acid (second step), but since the solution viscosity was extremely high, peracetic acid was not uniformly dispersed in the solution and heat was generated locally, so operation was continued. It was difficult to do.

[0042]

[Table 1]

[0043]

According to the present invention, a block copolymer (C) comprising a polymer block (A) mainly containing a vinyl aromatic hydrocarbon compound and a polymer block (B) mainly containing a conjugated diene compound. Alternatively, when the hydrogenated product (D) is epoxidized to obtain an epoxidized block copolymer (E), an epoxidized block copolymer having a small residual organic solvent content and gel content is obtained by a combination of four specific steps. It can be manufactured economically and easily.

Claims (2)

[Claims] 1. A block copolymer (C) comprising a polymer block (A) mainly containing a vinyl aromatic hydrocarbon compound and a polymer block (B) mainly containing a conjugated diene compound, or a hydrogenated product thereof. A method for producing an epoxidized block copolymer, which comprises the steps of (1) to (4) below when epoxidizing (D) to obtain an epoxidized block copolymer (E). (1) Block copolymer (C) or hydrogenated product (D) thereof
Is mixed with an organic solvent to obtain an organic solvent solution or an organic solvent slurry having a polymer concentration of 5 to 50% by weight. (2) A step of using an epoxidizing agent to epoxidize the unsaturated carbon bond existing in the polymer block (B) in the organic solvent solution or the organic solvent slurry. (3) A step of reducing the acid value of the solution or slurry to 5 mgKOH / g or less by washing and / or neutralizing the epoxidation reaction solution or slurry obtained in the above step. (4) The washed and / or neutralized epoxidation reaction solution or slurry is supplied to an evaporator, and the organic solvent or slurry is directly removed by evaporation to obtain a residual organic solvent content of 5,
A step of obtaining an epoxidized block copolymer (E) having a gel content of 000 ppm or less and a gel content of 5% by weight or less. 2. The method for producing an epoxidized block copolymer according to claim 1, wherein the epoxy equivalent of the epoxidized block copolymer (E) is 140 to 2,700.