JP2000034316A - Production of epoxidized block copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an epoxidized block copolymer scarcely causing the discoloration of a resin due to the corrosion of a material when producing the epoxidized block copolymer with a vented extruder made of a nitrided steel. SOLUTION: When an organic solvent is removed from a mixture comprising the organic solvent and an epoxidized block copolymer which is a reactional product and containing an acid with a vented extruder made of a nitrided steel to provide the epoxidized block copolymer, the sum total of the concentrations of the acid and water in the mixture fed to the vented extruder is <=2.00 wt.% when the amount of the mixture is 100 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an epoxidized block copolymer using a vent extruder. More specifically, the present invention relates to a method for producing an epoxidized block copolymer in which coloring of a resin caused by corrosion of equipment is suppressed by a vent extruder made of a low-grade material.

[0002]

2. Description of the Related Art A block copolymer comprising a vinyl aromatic hydrocarbon compound and a conjugated diene compound is transparent and has the same elasticity at room temperature as vulcanized natural rubber or synthetic rubber without vulcanization. Further, since it has the same processability as a thermoplastic resin at a high temperature, it is widely used in the fields of various modifiers and adhesion. For the purpose of further improving the performance as described above, an epoxidized block copolymer in which an unsaturated bond derived from a diene block of a block copolymer is epoxidized has been proposed. In the case where an organic peroxide is used as an epoxidation aid, an organic acid (hereinafter, simply referred to as an acid) is by-produced. Also, water is used to remove the acid. When the solvent is removed from the reaction mixture of the epoxidized block copolymer containing the acid and water having undergone the epoxidation reaction with a vent extruder to obtain the epoxidized block copolymer, the material of the extruder is nitrided steel (iron ) Is used, so that coloring of the resin due to corrosion of the material by acid and water becomes a problem.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an epoxidized block copolymer which is produced by using a vent extruder made of a nitrided steel, in which the resin is less colored due to corrosion of the material. An object of the present invention is to provide a method for producing a block copolymer.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have studied a method for producing an epoxidized block copolymer in order to solve such a problem. As a result, when the organic solvent is removed, the total amount of acid and water in the solvent is reduced. It has been found that the above problem can be solved by restricting the above, and the present invention has been completed.

That is, according to the present invention, an organic solvent is removed from a mixture containing an organic solvent and an acid composed of an epoxidized block copolymer, which is a reaction product, by a vent extruder made of a nitrided steel. A method for producing an epoxidized block copolymer, wherein the sum of the concentration of acid and water in a mixture supplied to a vent extruder is 2.00% by weight or less when the mixture is 100% by weight. I will provide a. Furthermore, the present invention provides a method for producing an epoxidized block copolymer, wherein the concentration of the acid in the mixture is 0.01 to 1.50% by weight. Also,
According to the present invention, in the method for producing an epoxidized block copolymer, the resin concentration in the mixture supplied to the vent extruder is 50% by weight or more and less than 95% by weight. And a method for producing the same.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
According to the production method of the present invention, the total concentration of acid and water in the epoxidation reaction mixture (mixture) supplied to the vent extruder is 2.00% by weight when the mixture is 100% by weight.
Or less, preferably 1.50% by weight or less. The acid concentration in the mixture is preferably 0.01 to 1.50% by weight. As a result, corrosion due to acid in the extruder is suppressed, and as a result, coloring of the epoxidized block copolymer due to corrosion is suppressed.

In the present invention, the epoxidized block copolymer is a diene block copolymer composed of a block mainly composed of a conjugated diene compound and a block mainly composed of a vinyl aromatic compound, or a hydrogenated product thereof (including a mixture of both). Conjugated diene-based block copolymers). The diene-based block copolymer is obtained by copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene, and the copolymer composition ratio (weight ratio of vinyl aromatic hydrocarbon compound / conjugated diene compound) is preferably 5 /. It is 95-70 / 30, more preferably 10 / 90-60 / 40. The number-average molecular weight of the diene-based block copolymer that can be used in the present invention is preferably 5,000 to 1,000,000, and more preferably 10,000.
000 to 500,000. For molecular weights lower than 5,000,
It is not preferable because the properties of the rubber-like elastic body are hardly exhibited, and if the molecular weight is higher than 1,000,000, it becomes difficult to melt. Here, the number average molecular weight means a standard polystyrene equivalent molecular weight measured by a GPC method.

The conjugated diene constituting the diene-based block copolymer is a diolefin having a pair of conjugated double bonds, for example, 1,3-butadiene, 2-methyl-1,2-methyl-1,3-butadiene.
3-butadiene (so-called isoprene), 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-
Includes 1,3-octadiene, phenyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, etc. Among them, 1,3-butadiene or isoprene is preferable because it is inexpensive and easily available. .
In producing the copolymer, these conjugated dienes are
Not only the species but also a mixture of two or more species may be used.

The vinyl aromatic hydrocarbon is a compound having an aromatic hydrocarbon group and a vinyl group, such as styrene, α-methylstyrene, o-methylstyrene and p-methylstyrene.
-Methylstyrene, alkyl-substituted styrene such as p-tert-butylstyrene, alkoxy-substituted styrene, vinylnaphthalene, alkyl-substituted vinylnaphthalene, vinylanthracene, divinylbenzene, vinyltoluene, and the like. Used.
These vinyl aromatic hydrocarbons can be used alone or as a mixture of two or more in producing the copolymer.

[0010] The hydrogenated product of the diene-based block copolymer is
It refers to a copolymer obtained by partially hydrogenating unsaturated carbon bonds present in a conjugated diene of a diene-based block copolymer by a hydrogenation reaction. The method for producing the hydrogenated product 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-43-6636 and the like, a method for producing a block copolymer by hydrogenating the block copolymer in an inert solvent in the presence of a hydrogenation catalyst can be mentioned. Although the amount of hydrogenation is not particularly limited, it is necessary that unsaturated carbon bonds capable of reacting with the epoxidizing agent remain in the molecule during the subsequent epoxidation reaction.

The structure of the diene-based block copolymer is not particularly limited. For example, when a block mainly composed of a vinyl aromatic compound is (A) and a block mainly composed of a conjugated diene compound is (B), ABA, B-
It may be a block copolymer of a vinyl aromatic hydrocarbon compound represented by ABA, ABABA and the like and a conjugated diene compound. The structure of the molecule itself may be any of linear, branched, radial, and the like, and may be an arbitrary combination thereof. In the diene-based block copolymer, the vinyl aromatic hydrocarbon compound may be uniformly distributed, or may be distributed in a tapered shape. In addition, the copolymerized portion may include a plurality of portions where the vinyl aromatic hydrocarbon compound is uniformly distributed and / or a plurality of portions where the vinyl aromatic hydrocarbon compound is distributed in a tapered shape.

After the diene block copolymer or its hydrogenated product is dissolved or slurried in a suitable organic solvent, at least one remaining double bond of the diene component block is epoxidized. The site to be epoxidized by the epoxidizing agent is an unsaturated carbon bond present in the diene copolymer block. Representative examples of organic solvents that can be used during epoxidation include pentane, hexane, heptane,
Linear and branched hydrocarbons such as octane and their alkyl-substituted derivatives, cyclopentane, cyclohexane,
Alicyclic hydrocarbons such as cycloheptane and their alkyl-substituted derivatives, aromatic and alkyl-substituted aromatic hydrocarbons such as benzene, naphthalene, toluene and xylene, and aliphatic carboxylic esters such as methyl acetate, ethyl acetate and propyl acetate And halogen-containing hydrocarbons such as chloroform. Among these, it is preferable to use cyclohexane, ethyl acetate, chloroform, toluene, xylene, and hexane in view of the solubility of the block copolymer or its hydrogenated product and the ease of recovering the solvent thereafter.

Representative examples of the epoxidizing agent that can be used in the epoxidation reaction include organic peracids such as peracetic acid, perbenzoic acid, formic acid, and trifluoroperacetic acid, hydrogen peroxide, and hydrogen peroxide. And low molecular fatty acids in combination. At the time of epoxidation, a catalyst can be used if necessary. Of these, peracetic acid, which is industrially produced in large quantities, is inexpensive, and has relatively high stability, is preferred as the epoxidizing agent. 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 unsaturated carbon bond in the block copolymer used or its hydrogenated product. Depending on the conditions such as the amount, an appropriate amount can be arbitrarily used.

The epoxidation reaction temperature varies depending on the type and amount of the epoxidizing agent used, the solvent used, the block copolymer or its hydrogenated product, and is not particularly limited. For example, when peracetic acid is used as the epoxidizing agent, the reaction temperature is preferably 0 to 70 ° C. 0 ° C
In the following, the reaction rate is low, and if it exceeds 70 ° C., it is not preferable because the formed epoxy group is ring-opened or the decomposition of peracetic acid proceeds. In order to improve the stability of peracetic acid, phosphates may be added to the reaction system during the epoxidation reaction. The epoxidation reaction time is preferably 0.1 to 72 hours from the viewpoint of productivity. After completion of the epoxidation reaction, a chelating agent may be added to the reaction solution. In some cases, it is also preferable to neutralize acids generated during the epoxidation reaction with an aqueous alkali solution or wash with a small amount of pure water.

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 diene block copolymer used or its hydrogenated product Any suitable amount can be used depending on the conditions such as the amount of unsaturated carbon bond, but the epoxy equivalent of the epoxidized block copolymer finally obtained is 140
It is preferred to select the amount of epoxidizing agent to be ~ 2,700. The epoxy equivalent is more preferably 200
~ 2,000. If the epoxy equivalent is smaller than 140, the elastic properties of the polymer are hardly exhibited, which is not preferable. If it is larger than 2,700, the compatibility with various resins due to the epoxidation, the adhesion to various materials, etc. It is not preferable because specific physical properties are hardly developed. The epoxy equivalent is calculated by the formula: epoxy equivalent = 1,600 / {oxygen oxygen concentration in epoxidized block copolymer (% by weight)}, and indicates the weight of epoxidized block copolymer per 1 mol of oxirane oxygen. Oxirane oxygen concentration is
It is determined by titration with an acetic acid solution of hydrogen bromide. If the epoxy equivalent is large, the oxirane oxygen concentration becomes low, and if the epoxy equivalent is small, the oxirane oxygen concentration becomes high.

In the present invention, the solvent is then removed from the epoxidation reaction solution using a vent extruder. At the time when the solvent is removed, the total amount of the acid and water in the epoxidation reaction solution is reduced. Is 2.00% by weight based on 100% by weight of the epoxidation reaction mixture (mixture).
The following is required, and preferably 1.50% by weight or less. The concentration of the acid in the mixture is preferably 0.0
1 to 1.50% by weight. When the total concentration of the acid and the water is 2.00% by weight or less, the occurrence of corrosion is suppressed even if nitrided steel is used as the process material, and the coloring of the epoxidized block copolymer due to the corrosion can be suppressed. Note that, in the present invention, the mixture as it is after the epoxidation reaction is not subjected to solvent removal using a vent extruder, and other means,
For example, preliminarily remove the solvent by a stirring film evaporator, etc.
The concentrated mixture may be supplied to a vent extruder. The acid concentration and the water content of the mixed solution supplied to the vented extruder can be adjusted to preferable values by washing the reaction solution with water and preliminary desolvation by a stirred film evaporator.

The vent type extruder used in the present invention has a high solvent removing ability and a small amount of burnt resin adhered. The vented extruder preferably has at least one, preferably 1 to 10, and more preferably 1 to 5, vent portions for deaeration. The number of shafts is preferably at least one, particularly preferably two or more. Among these, a twin-screw vent type extruder is versatile and particularly preferred. As the 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) is good, and the meshing structure of the screw is as follows. Either "meshing" or "non-meshing" may be used, and the rotation direction may be either the same direction or a different direction. Among the twin-screw vented extruders, those having a structure that allows a heat medium to pass through the inside of the screw are particularly preferable. An extruder having such a structure is preferable because it can sufficiently supply a large amount of heat required when the organic solvent evaporates. Further, an extruder having a continuous gas phase at the upper portion is preferable from the viewpoint of solvent removal efficiency.

The temperature inside the extruder and the pressure inside the extruder are as follows:
Selection should be made in consideration of processing capacity, polymer characteristics (viscosity, thermal stability, etc.), solvent type, concentration, product quality, etc. The preferred temperature inside the extruder is 80-300 ° C, more preferably 120-250 ° C. The temperature inside the extruder is 80 ° C
If the temperature is lower than 300 ° C., the solvent is not sufficiently removed. If the temperature 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 and a large amount of gel is generated, the melt viscosity is increased, and fish eyes are easily generated and molding defects are caused, which is not preferable. The organic solvent is removed by a vent extruder, and the gel content in the finally obtained epoxidized copolymer is preferably 5% by weight or less, more preferably 3% by weight or less, more preferably 1% by weight. % Or less.

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

The organic solvent was directly removed from the epoxidation reaction mixture by a vent extruder, and the content of the residual organic solvent in the finally obtained epoxidized block copolymer was 5,0.
It is preferably at most 00 ppm, more preferably at most 1,000 ppm, particularly preferably at most 500 ppm. If the content of the organic solvent is more than 5,000 ppm, foaming and odor are generated when molding into a product form, which is not preferable. Adjustment of the residual organic solvent content depends on the temperature of the extruder,
It can be easily performed by changing the conditions such as the pressure inside the extruder and the processing speed. The concentration of the epoxidized block copolymer in the epoxidation reaction mixture supplied to the vent extruder is 50% by weight or more and less than 95% by weight, preferably 7% by weight.
0 to 85% by weight. When the concentration is less than 50% by weight, the amount of the solvent increases, and the solvent removing ability becomes insufficient. When the concentration is more than 95% by weight, the viscosity of the mixture to be supplied is too high, and the operation becomes difficult.

The epoxidized block copolymer directly desolvated by an extruder can be selected from any of a strand, a pellet, a foamed crumb, a granule, and a powder, but is preferably a pellet.

The epoxidized block copolymer of the present invention may optionally contain various additives such as heat stabilizers, antioxidants, crosslinking agents, ultraviolet absorbers, or inorganic materials such as silica, talc and carbon. Agents, plasticizers, and softeners such as oils can be compounded and used. The timing of these additions is not particularly limited, and may be any step until the epoxidized block copolymer is finally obtained.

The epoxidized block copolymer obtained by the method of the present invention has little coloring,
It can be used as various molded products such as injection molded products and hollow molded products of various shapes, as well as modifiers for various thermoplastic resins, adhesives, adhesive materials, asphalt modifiers, home appliances, automobile parts, and industrial It is useful as a material for parts, household goods, toys and the like.

[0024]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. In addition, measurement and evaluation were performed by the following methods. 1. Determination of corrosion Dissolve the obtained epoxidized block copolymer in a solvent,
Iron content in the copolymer was quantified by atomic absorption analysis. 2. Resin coloring degree The obtained epoxidized block copolymer pellets were
Pressed at 0 ° C, 100 kg / cm ² pressure, thickness 2m
m was molded, and the degree of coloring was visually observed. 3. Measurement of the concentration of acid and water in the mixture The water in the sample was measured by the Karl Fischer method. The concentration of the acid was calculated by dissolving the sample in an appropriate amount of THF, performing neutralization titration with KOH using phenolphthalene as an indicator, and converting to acetic acid. The unit is (mg · KOH / g). The acetic acid conversion means that all acids neutralized by KOH are acetic acid and are converted to weight%.

Example 1 1,200 kg of a block copolymer of polystyrene-polybutadiene-polystyrene (SBS, "TR-2000" manufactured by Nippon Synthetic Rubber Co., Ltd.) was completely dissolved in 2,500 kg of ethyl acetate, and Then, 675 kg of a 30% by weight solution of peracetic acid in ethyl acetate was continuously added dropwise thereto, and an epoxidation reaction was carried out at 40 ° C. for 3 hours with stirring. Next, the reaction solution was returned to room temperature and washed with pure water to obtain an epoxidized polystyrene-polybutadiene-polystyrene block copolymer in ethyl acetate. The volatile content of the epoxidized block copolymer in ethyl acetate solution is 66.86% by weight, and the concentration of the epoxidized block copolymer is 29.95.
% By weight. The acid concentration in this solution was 0.078% by weight, and the water content in the solution was 3.094% by weight.
This solution was supplied to a stirred film type evaporator having a heat transfer area of 1.0 m ² and a screw for feeding liquid immediately before the outlet of the concentrated liquid.
The stirring film type evaporator has a heating medium supply temperature of 140 ° C. and a system pressure of 1
The operation was performed under the conditions of 00 mmHg and the rotation speed of the stirring blade was 240 rpm. As a result, the volatile concentration of this solution was 21.
00% by weight (concentration of epoxidized block copolymer is 7
8.38% by weight) and the acid concentration in the solution is reduced to 0.0
17% by weight, and the water content in the solution was reduced to 0.6% by weight.
Next, the concentrate was screwed with an outer diameter of 58 mm and L / D
= 36, fed to a twin-screw vented extruder made of nitrided steel without rear vents having four vents. The operation of the extruder
The heating medium supply temperature was 160 ° C., the system pressure was 100 mmHg, and the screw rotation speed was 110 rpm. Further, an ethyl acetate solution of the epoxidized block copolymer was supplied to the stirred film type evaporator such that the production rate of the polymer obtained by the twin-screw vented extruder was 45 kg / h. The residual solvent content in the copolymer after the removal of the solvent was 1,000 ppm, and the epoxy equivalent of the copolymer was 520. Table 1 shows the measurement results of the coloring and the iron content of the obtained copolymer.

Example 2 and Comparative Example 1 Using the liquid obtained from the stirred film type evaporator obtained in Example 1, the solid content, acid, and water content of the mixture fed to the vented extruder shown in Table 1 were obtained. The concentration was adjusted so as to become the concentration. Next, the prepared supply mixtures were supplied to a twin-screw vented extruder under the same conditions as in Example 1 to remove the solvent. Table 1 shows the measurement results of coloring and iron content of the obtained copolymer.

[0027]

[Table 1]

[0028]

As described above, when the organic solvent is separated from the mixture with the organic solvent using a vent extruder to obtain an epoxidized block copolymer, the acid and water in the mixture supplied to the vent extruder are obtained. Of the epoxidized block copolymer resin caused by corrosion of a relatively inexpensive extruder made of nitrided steel can be suppressed by suppressing the total concentration of the epoxidized block copolymer resin to a certain value or less. According to the present invention, a method for producing an epoxidized block copolymer in which coloring of a resin due to corrosion is suppressed is provided.

Claims (3)

[Claims] An epoxidized block copolymer is obtained by removing an organic solvent from a mixture containing an organic solvent, an epoxidized block copolymer as a reaction product, and an organic acid by a vent extruder made of a nitrided steel to obtain an epoxidized block copolymer. The sum of the concentrations of organic acid and water in the mixture fed to the vented extruder makes the mixture 10
A method for producing an epoxidized block copolymer, wherein the amount is not more than 2.00% by weight when the amount is 0% by weight. 2. The process for producing an epoxidized block copolymer according to claim 1, wherein the concentration of the organic acid in the mixture supplied to the vent extruder is 0.01 to 1.50% by weight. 3. The method for producing an epoxidized block copolymer according to claim 1, wherein the resin concentration in the mixture supplied to the vent extruder is 50% by weight or more and less than 95% by weight.