JPH10279728A - Recovery of block copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of recovering block copolymer that contains a reduced amount of gels, has excellent color tone, transparency and resistance to devitrification, has a reduced amount of residual solvent and high process stability. SOLUTION: When a copolymer is obtained by direct removal of the hydrocarbon solvent from a solution of a conjugated diene-block copolymer containing 10-65 wt.% of vinyl aromatic hydrocarbon, (1) an alcohol is added, (2) water and carbon dioxide are added to regulate the pH to 6.5-8.5, (3) a stabilizer is added, (4) the solution is preheated to cause depressurization in the feed zone of the endless screw and remove 75-95 wt.% of the solvent in a short time. Then, the remaining polymer is heated again by heat transfer from the barrel and screw rotation, 0.5-2 wt.% of water is injected at least one position in the exhaustion zone, then 5-25 wt.% of the solvent is removed in the exhaustion zone in front of the feed hopper and pelletized through the die.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for directly desolvating a solvent from a solution of a block copolymer or a hydrogenated product thereof comprising a conjugated diene and a vinyl aromatic hydrocarbon and containing relatively few vinyl aromatic hydrocarbons. The present invention relates to a method for recovering a block copolymer or a hydrogenated product thereof having a small amount of gel in a pellet, excellent color tone, transparency and devitrification resistance, a small amount of residual solvent, and good processing stability.

[0002]

2. Description of the Related Art A block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene is transparent and vulcanized natural rubber or vulcanized without vulcanization when the content of the vinyl aromatic hydrocarbon is relatively small. It has the same elasticity as synthetic rubber at room temperature, and has the same processability as thermoplastic resin at high temperature, so footwear, plastic modification, asphalt,
Widely used in the adhesive field. In producing these block copolymers, polymerization is usually performed in a hydrocarbon solvent inert to the catalyst, and the resulting block copolymer is uniformly dissolved or suspended in the solvent. Since it is obtained in a state, a step of separating the block copolymer and the solvent is required. There are various methods for separating the block copolymer and the solvent. One of the methods is to directly remove the solvent from the block copolymer solution by removing the solvent from the vent extruder in one step. There is a known method for recovering wastewater.

[0003] For example, JP-A-51-86588 and JP-A-51-41087 describe a method of desolvating a styrene-based block copolymer resin using a twin-screw multi-stage extruder. If you simply go through this process,
The color tone of the obtained block copolymer or its hydrogenated product is inferior. JP-A-63-284203 discloses that
A method is described in which an elastic polymer solution is introduced into a twin-screw vent extruder equipped with an endless screw to remove the solvent, but the same applies in this case. JP-A-63-314
No. 207 discloses a method of recovering a polymer by using a twin-screw vent extruder provided with a pump between a screw tip and a die in recovering the polymer.
After adding a specific stabilizer to JP-175304,
A method of directly removing the solvent using a twin-screw multi-stage vent extruder is described.

However, all of these processes are strongly subject to heat and shear, and the block copolymer or its hydrogenated product obtained by the conventionally known simple quenching method and addition of a stabilizer system can be obtained. Quality is not sufficient, especially in terms of prevention of gel formation, inhibition of molecular chain scission and cross-linking reaction of desolvated polymer, color tone, devitrification resistance, etc. Is not disclosed at all. Therefore, the block copolymer or its hydrogenated product is processed under a high-temperature condition. In particular, when the styrene-based resin composition is processed under a high-temperature condition or has a thickness of 0.1 m.
In the case of processing into a thin sheet, film, or the like having a thickness of not more than m, a problem such as poor printing due to gel mixing occurred. Further, when producing a block copolymer or a hydrogenated product thereof, it is not sufficient to efficiently operate a solvent having a small residual solvent, and a solution to the problem is desired.

[0005]

The object of the present invention is to produce a block copolymer or a hydrogenated product thereof with a reduced amount of gel in pellets, excellent color tone, transparency and resistance to devitrification, and reduced residual solvent content. It is an object of the present invention to provide a method for recovering a block copolymer or a hydrogenated product thereof having a small amount and good processing stability.

[0006]

Means for Solving the Problems The method of the present invention has improved points such as prevention of gel formation, suppression of molecular chain scission and cross-linking reaction of a desolvated polymer, color tone, devitrification resistance and the like. According to the present invention, a block copolymer or a hydrogenated product thereof is processed under high-temperature conditions, particularly under high-temperature conditions when a styrene-based resin composition is formed, or a thin sheet or film having a thickness of 0.1 mm or less. Etc.
The conventional problems of poor fluidity and poor printing due to gel mixing have also been solved.

That is, the present invention is as follows. [1] In a hydrocarbon solvent, a vinyl aromatic hydrocarbon content obtained by polymerizing a conjugated diene and a vinyl aromatic hydrocarbon using an organolithium compound as an initiator is 10% by weight or more and less than 65% by weight. In obtaining the block copolymer or its hydrogenated product by directly removing the solvent from the solution of the block copolymer or its hydrogenated product, (1)
In an active polymer solution of a block copolymer or a hydrogenated product thereof,
A step of adding an alcohol into the polymerization vessel, (2) a solution of the block copolymer or a hydrogenated product thereof in an amount of 0.005 to 100 parts by weight based on 100 parts by weight of the block copolymer or the hydrogenated product thereof;
After adding 0.1 parts by weight of water, carbon dioxide is added to adjust the pH of the solution to a range of 6.5 to 8.5, or after adding carbon dioxide, 0.005 to 0.1 Adjusting the pH of the solution to a range of 6.5 to 8.5 by adding part by weight of water; (3) adding the block copolymer or its water to the solution of the block copolymer or its hydrogenated product; A) 2- [1- (2-hydroxy-3,5-di-
t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate in an amount of 0.03 to 2 parts by weight,
B) 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, n-octadecyl 3- (3,5-di-tert-)
Butyl-4-hydroxyphenyl) propionate, tetrakis [methylene-3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate] methane,
1,3,5-trimethyl-2,4,6-tris (3,5
-Di-t-butyl-4-hydroxybenzyl) benzene, 2,4-bis- (n-octylthio) -6- (4-
Hydroxy-3,5-di-t-butylanilino) -1,
0.03 to 2 parts by weight of at least one of 3,5-triazine,
C) 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, 2-[[2,4,8,
10-tetrakis (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphefine-
6-yl] oxy] -N, N-bis [2-[[2,4,
8,10-tetrakis (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphefin-6-yl] oxy] -ethyl] -ethanamine,
A step of adding 0.01 to 2 parts by weight of at least one kind of 2,4-bis [(octylthio) methyl] -o-cresol as a stabilizer, (4) a solution of the block copolymer or a hydrogenated product thereof In advance to a temperature of 130-180 ° C.,
It was introduced into the feed hopper of the endless screw to create a pressure reduction in the feed zone, and after 75-95% by weight of the solvent was removed in a short time, it was reheated by heat transfer from the barrel and rotation of the screw. ２2% by weight of water is injected into at least one point between the exhaust zones and 5-25% by weight of the solvent
After the polymer temperature in all zones of the exhaust zone located in front of the feed hopper is removed at 150-200 ° C., then introduced into the die located downstream and cut by a cutter, located immediately after the die Obtaining a block copolymer or a hydrogenated product thereof.

Hereinafter, the present invention will be described in detail. (A) Step of Producing a Solution of Block Copolymer or Its Hydrogenated Product In the present invention, the block copolymer is a thermoplastic elastomer having a relatively low content of vinyl aromatic hydrocarbon, and Hydrogen content is more than 10% by weight,
It is less than 65% by weight. The block copolymer in the present invention is a block copolymer having at least one polymer block mainly composed of a vinyl aromatic hydrocarbon and at least one polymer block mainly composed of a conjugated diene. Here, the polymer block mainly composed of a vinyl aromatic hydrocarbon is defined as having a vinyl aromatic hydrocarbon content of 5%.
0% by weight or more of a copolymer block of a vinyl aromatic hydrocarbon and a conjugated diene and / or a homopolymer block of a vinyl aromatic hydrocarbon, wherein a polymer block mainly composed of a conjugated diene means a conjugated diene. 5 shows a conjugated diene and vinyl aromatic hydrocarbon copolymer block and / or a conjugated diene homopolymer block contained in an amount exceeding 50% by weight.

When a random copolymer portion of a vinyl aromatic hydrocarbon and a conjugated diene is present in a polymer block mainly containing a vinyl aromatic hydrocarbon or a polymer block mainly containing a conjugated diene, it is copolymerized. Even if the vinyl aromatic hydrocarbons are evenly distributed in the polymer block,
It may be distributed in a taper (gradual decrease) shape. The copolymer portion may have a plurality of portions where vinyl aromatic hydrocarbons are uniformly distributed and / or a plurality of portions where the vinyl aromatic hydrocarbons are distributed in a tapered shape.

The block copolymer used in the present invention can be basically produced by a conventionally known method.
No. 9286, JP-B-43-17979, JP-B-48-2423, JP-B-49-36957, JP-B-57-49567, and JP-B-58-11.
The method described in Japanese Patent Application Publication No. 446/446 and the like can be mentioned, but production conditions must be set for each constituent polymer so as to satisfy the requirements described below. All of the above-mentioned known methods are methods of block copolymerizing a conjugated diene and a vinyl aromatic hydrocarbon using an anionic initiator such as an organic lithium compound in a hydrocarbon solvent.

The polymer structure of the block copolymer used in the present invention includes, for example, A- (BA) _n , A- (BA) _n -B, B- (AB) _{n + 1} , In the above formula, A is a polymer block mainly composed of vinyl aromatic hydrocarbon, and B is a polymer block mainly composed of conjugated diene, and the boundary between the A block and the B block is always clearly distinguished. N is an integer of 1 or more, generally 1 to 5.) or a general formula: [(AB) _k ] _{m + 2} -X , [(AB) _k -A] _{m + 2} -X, [(BA) _k ] _{m + 2} -X, [(BA) _k -B] _{m + 2} -X, In the above, A and B are the same as described above, and k and m
Is an integer of 1 or more, generally 1 to 5. X represents a residue of a coupling agent such as silicon tetrachloride or tin tetrachloride or a residue of an initiator such as a polyfunctional organolithium compound. )) Or a mixture of these block copolymers having an arbitrary polymer structure.

The vinyl aromatic hydrocarbon used in the present invention includes styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, There are vinylanthracene, 1,1-diphenylethylene and the like, and particularly common one is styrene. These may be used alone or in combination of two or more. The conjugated diene is a diolefin having a pair of conjugated double bonds, for example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3- Butadiene, 1,3
-Pentadiene, 1,3-hexadiene, etc.
Particularly common ones include 1,3-butadiene and isoprene. These may be used alone or in combination of two or more.

Examples of the hydrocarbon solvent include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane and octane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane and ethylcyclohexane; Aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene can be used. These may be used alone or in combination of two or more.

The organic lithium compound is an organic monolithium compound, an organic dilithium compound, or an organic polylithium compound having one or more lithium atoms bonded in a molecule.
Specific examples include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, se
c-butyllithium, tert-butyllithium, hexamethylenedilithium, butadienyldilithium, isoprenyldilithium and the like. These may be used alone or in combination of two or more.

In the present invention, for the purpose of adjusting the polymerization rate, changing the microstructure (ratio of cis, trans, and vinyl) of the polymerized conjugated diene portion, and adjusting the reaction ratio between the conjugated diene and the vinyl aromatic hydrocarbon. Polar compounds and randomizers can be used. Examples of polar compounds and randomizing agents include tetrahydrofuran, diethylene glycol dimethyl ether, ethers such as diethylene glycol dibutyl ether, amines such as triethylamine, tetramethylethylenediamine, thioethers, phosphines, phosphoramides, alkylbenzene sulfonates, potassium and sodium salts. Alkoxide and the like.

In the method of the present invention, the polymerization temperature for producing the block copolymer is generally from -10 ° C to 150 ° C.
° C, preferably 40 ° C to 120 ° C. The time required for the polymerization varies depending on the conditions, but is usually within 10 hours, particularly preferably 1 to 5 hours. Further, it is desirable to replace the atmosphere of the polymerization system with an inert gas such as nitrogen gas. The polymerization pressure is not particularly limited, as long as it is a pressure range sufficient to maintain the monomer and the solvent in a liquid phase within the above-mentioned polymerization temperature range. Further, it is necessary to take care that impurities such as water, oxygen, carbon dioxide, etc., which inactivate the catalyst and the living polymer, do not enter the polymerization system.

The weight average molecular weight of the block copolymer thus obtained is generally 5,000 to 100,000.
0, preferably 10,000 to 500,000. The amount of hydrocarbon in the block copolymer solution is generally 50 parts by weight to 200 parts by weight based on 100 parts by weight of the block copolymer.
0 parts by weight. In some cases, the block copolymer is insoluble in a hydrocarbon solvent and can be obtained in a suspended state, depending on the properties of the block copolymer. In the present invention, these are also referred to as a block copolymer solution.

In the present invention, a block copolymer solution obtained by partially or selectively hydrogenating the above-obtained block copolymer by a hydrogenation reaction (hydrogenation reaction) may be used. it can. In the hydrogenation reaction, if necessary, the active terminal of the block copolymer solution may be inactivated by a reaction terminator, or may be left as it is. In the present invention, the hydrogenation rate of the hydrogenation reaction can be arbitrarily selected, and when improving the heat deterioration resistance while maintaining the properties of the unhydrogenated block copolymer, the aliphatic diene based on the conjugated diene is used. 3% or more and less than 80%, preferably 5% of heavy bonds
As described above, hydrogenation of less than 75% is preferable in order to improve heat deterioration resistance and weather resistance.
It is recommended to hydrogenate more than 0%. The hydrogenation rate can be measured by a nuclear magnetic resonance apparatus or the like.

The catalyst used in the hydrogenation reaction includes:
(1) a supported heterogeneous catalyst in which a metal such as Ni, Pt, Pd, and Ru is supported on a carrier such as carbon, silica, alumina, and diatomaceous earth; and (2) an organic catalyst such as Ni, Co, Fe, and Cr A so-called Ziegler catalyst using a salt or an acetylacetone salt and a reducing agent such as organic Al, or a so-called organic complex catalyst such as an organometallic compound such as Ru or Rh, or an organic Li, organic Al, or organic Mg as a reducing agent for a titanocene compound A homogeneous catalyst using such as is known. As a specific method, Japanese Patent Publication No. 42-8704 and Japanese Patent Publication No.
No. 6636, preferably Japanese Patent Publication No. Sho.
According to the methods described in JP-A-3-4841 and JP-B-63-5401, a hydrogenated block copolymer solution can be obtained by hydrogenation in an inert solvent in the presence of a hydrogenation catalyst.

(B) Step (1): Step of Adding Alcohol An active polymer solution of a block copolymer or a hydrogenated product thereof is
This is the step of adding alcohol into the polymerization vessel. This step is effective in reducing gels mixed in the finally obtained block copolymer or its hydrogenated product. By using a small amount of alcohol as a reaction terminator, it is discharged together with the solvent and does not remain in the polymerization vessel, and does not affect the next polymerization system.

Examples of the alcohol include aliphatic saturated alcohols, aliphatic unsaturated alcohols, alicyclic alcohols, aromatic alcohols and the like. In particular, aliphatic saturated alcohols such as methanol, ethanol, propanol, butanol,
Hexanol, heptanol and the like are preferred. In particular,
Alcohols having 1 to 3 carbon atoms, for example, methanol, ethanol, and propanol have low boiling points and excellent volatility, and do not remain in the block copolymer obtained by desolvation or its hydrogenated product, so that there is no odor. preferable. In the present invention, the addition amount of the alcohol is not particularly limited, but is preferably 0.6 to 1.5 times equivalent to the organic lithium compound.

(C) Step (2); Step of Adding Water and Carbon Dioxide Gas The solution of the block copolymer or its hydrogenated product is added with 0 parts by weight based on 100 parts by weight of the block copolymer or its hydrogenated product. .
005 to 0.1 parts by weight, preferably 0.01 to 0.05
The addition of water in parts by weight and carbon dioxide gas resulted in a pH of the solution of 6.5 to 6.5.
This is a step of adding a predetermined amount so as to fall within the range of 8.5. If the amount of water added is less than 0.005 parts by weight, the block copolymer obtained by long-term storage at a high temperature (about 80 ° C. or higher) and then desolvation is inferior in color tone and 0.1% by weight. Exceeding the number of parts is not preferred because the transparency and devitrification resistance of the block copolymer or its hydrogenated product obtained by removing the solvent are reduced.

The initiator used for producing the block copolymer or a solution of the hydrogenated product thereof is an organic lithium compound, and the polymer solution is a strong base. When a stabilizer such as a phenolic antioxidant is added to the polymer solution in such a state, many of the stabilizers cause undesirable deterioration under basic conditions, so that the color tone of the polymer deteriorates and the thermal stability decreases. Occurs. In this step, by adjusting the pH of the solution using carbon dioxide gas, a block copolymer having excellent quality or a hydrogenated product thereof can be obtained. If the pH of the solution exceeds 8.5, the color is inferior,
If it is less than 6.5, the color tone is not improved, and carbon dioxide gas is present in the block copolymer or its hydrogenated solution as it is. Here, the pH of the solution is such that a part of the solution is sampled, distilled water (having a pH of 7.0 ± 0.5) of the same weight as the solution is sufficiently mixed with the solution, and the mixture is allowed to stand for two layers. P of separated water layer
H is displayed. PH can be measured using a glass electrode type hydrogen ion concentration meter (PH meter).

The carbon dioxide gas used in the present invention may be gaseous or solid, and may be added in a state of being dissolved in water or a solvent. When adding carbon dioxide, it is essential to add water within the scope of the present invention, and any order of addition of water and carbon dioxide may be added first. Water and carbon dioxide may be added and mixed continuously by a static mixer or an in-line mixer, or may be mixed by a batch in a tank.

(D) Step (3): Step of Adding a Stabilizer In the present invention, after adding and mixing the above-mentioned carbon dioxide gas, adding a stabilizer may comprise adding a block copolymer or a hydrogenated product thereof. It is necessary to prevent deterioration due to oxidative deterioration or the like. The stabilizer used in the present invention may be added as it is to a solution or may be added after being dissolved in a hydrocarbon solvent.

The stabilizer used in the present invention may be prepared by adding A) 2- [1- (2) to the solution of the block copolymer or the hydrogenated product thereof with respect to 100 parts by weight of the block copolymer or the hydrogenated product thereof. -Hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate in an amount of 0.03 to 2 parts by weight, preferably 0.05 to 1 part by weight, B) 2 -T-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, n-octadecyl 3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate, tetrakis [methylene-3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate] methane,
1,3,5-trimethyl-2,4,6-tris (3,5
-Di-t-butyl-4-hydroxybenzyl) benzene, 2,4-bis- (n-octylthio) -6- (4-
Hydroxy-3,5-di-t-butylanilino) -1,
0.03 to 2 parts by weight of at least one of 3,5-triazine,
Preferably 0.05 to 1 part by weight, C) 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, 2-[[2,4,8,
10-tetrakis (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphefine-
6-yl] oxy] -N, N-bis [2-[[2,4,
8,10-tetrakis (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphefin-6-yl] oxy] -ethyl] -ethanamine,
One or more kinds of 2,4-bis [(octylthio) methyl] -o-cresol are contained in an amount of 0.01 to 2 parts by weight, preferably 0.1 to 2 parts by weight.
03 to 1 part by weight. When the amount of each of the stabilizers of components A) and B) is less than 0.03 parts by weight and the amount of the stabilizer of component C) is less than 0.01, the effect of improving the stability is not recognized. Are added in an amount of more than 2 parts by weight, respectively, the effect beyond the range of the present invention is not exhibited.

(E) Step (4); Step of Desolvating This step is a step of separating the solvent from the solution of the block copolymer or its hydrogenated product. In this step, the extruder having a twin-screw endless screw and a rear exhaust
A solution of the block copolymer or its hydrogenated product at 180 ° C. is introduced into a feed hopper of an endless screw to depressurize the feed zone and remove 75 to 95% by weight of the solvent in a short time. This pressure reduction is adjusted by a control valve arranged in a line supplying the endless screw.

Here, the temperature range of 130 to 180 ° C.
This is a temperature suitable for optimizing the solvent removed in the rear exhaust zone. At a temperature lower than 130 ° C., the removal of the solvent is less than 75% by weight, and entrainment occurs in the subsequent exhaust zone to hinder the operation, and the solvent cannot be sufficiently removed. The amount of residual solvent in the polymer or its hydrogenated product is increased, which is not preferable. On the other hand, when the temperature exceeds 180 ° C., the pressure in the supply line increases, and it becomes difficult to adjust the pressure using the control valve.

The amount of solvent removed in a short time is the amount of solvent removed in the rear exhaust zone. The preferred residual solvent amount in the finally obtained pellet of the block copolymer or its hydrogenated product is 2,000 ppm or less, and preferably 1,000 ppm or less. Next, since the polymer temperature in the rear exhaust zone is considerably reduced, reheating is performed in the exhaust zone located in the front, and this reheating must be performed in such a manner that the polymer temperature in all zones is set in the range of 150 to 200 ° C. . In the present invention, the block copolymer or its hydrogenated product has a high conjugated diene content,
If the temperature exceeds 0 ° C., the thermal stability at the time of breaking and crosslinking of the polymer molecular chain and molding is inferior. The polymer solution, reheated to a temperature of 150-200 ° C., has a 0.5-0.5
Stepwise removal of 5-25% by weight of the remaining solvent is carried out stepwise by injection of 2% by weight of water. By adding 0.5 to 2% by weight of water to the block copolymer or its hydrogenated product, the solvent removal efficiency can be further increased.

The twin-screw vent extruder used in the present invention preferably has a structure having a gear pump between the tip of the screw and the discharge die. As a result, even if the screw rotation speed is increased, a smooth discharge is possible, so that the pressure increase of the block copolymer or its hydrogenated product is suppressed, the polymer temperature is prevented from increasing, and the heat stability is improved. I do. The die is used for underwater cutting or hot cutting, and the cutter used has 2 to 12 blades according to the required pellet size.

The twin-screw vent extruder used in the present invention has 2 to 5 exhaust vent zones, and L / D = 30 to 60.
(L is the length of the screw, D is the outer diameter of the screw), and a meshing type biaxial vent extruder of the same direction is preferable. FIG. 1 shows an example of a process using a meshing type co-directional twin screw vent extruder in the present invention. In FIG.
The polymer solution is introduced into the feed hopper (4) of an extruder (1) equipped with a twin screw endless screw (2). The pressure and feed rate in the extruder are controlled by a control valve (3). The extruder has a rear exhaust zone (5) through which most of the solvent is removed. The polymer is transported forward by a twin-screw endless screw (2). In order to remove the remainder of the solvent, a number of evacuation zones (6) are arranged in the extruder (1), between these evacuation zones introduction means (10) for introducing water to facilitate the removal of the solvent. 7) is provided. Via a gear pump (8) located in front of it, it passes through a die (9) and is cut into a pellet-like form by a cutter (10).

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION In order to explain the present invention in more detail, examples of the present invention will be shown below, but it is needless to say that the present invention is not limited to these examples.
In addition, the measuring method and the evaluation method are as follows. (1) Color Tone The b-value of the pellet was measured using a Nippon Denshoku Industries Co., Ltd. ND-V6B type total vision measuring instrument, and the color tone was examined. The larger the b value, the greater the apparent yellowness.

(2) Transparency The pellets are compression-molded (200 ° C.) to form a sheet having a thickness of 2 mm, and liquid paraffin is applied to both sides of the sheet, and the haze (%) conforms to ASTM D-1003. And measured. (3) Devitrification A 2 mm-thick sheet was immersed in hot water at 60 ° C. for 2.5 hr, and the haze (%) of each test piece was measured under the same conditions as in (2) above. The difference from the haze (%) before immersion was determined. The larger the difference, the worse the devitrification resistance.

(4) Gel amount 5 g of a pellet as a weight was dissolved in 200 ml of toluene, and filtered by suction with a 70 mm diameter filter paper (thickness: 0.2 mm, retained particle diameter: 6 μm, collection efficiency: 65%). After staining the residue with (Violet 36) and leaving it for 5 minutes,
The gel amount of the filter paper was visually determined based on the following criteria. ◎: Large number is 0, or medium is 3 or less, or small is 5 or less. ：: Large number is 0, or medium is 4 to 10, or small is 6.
~ 20 △: Large number is 1, or Medium is 11 to 20, or Small is 21 to 40 ×: Large number is 2 or more, Medium is 21 or more, or Small is 41 or more (Small have a diameter of less than 0.2 mm, medium has a diameter of 0.2 to 0.2 mm.
(5) The molecular chain is larger than 0.5 mm in diameter.) (5) Molecular chain cutting and cross-linking The pellet is heated to a temperature of 230 ° C.
Let stand for 0 minutes. The molecular weight distribution of the pellet was measured by gel permeation chromatography (GPC), and was superposed on the same area as the molecular weight distribution of the pellet before standing, and the difference between the low molecular weight side and the high molecular weight side was expressed in terms of% by weight.

(6) Melt Retention Ratio 15 parts by weight of pellets and general-purpose polystyrene (Styrone 6)
85) Melt flow index (M1: g / 10 min) of pellets obtained by kneading and granulating 85 parts by weight of an extruder at a temperature of 220 ° C. and a load of 2.16 kg for 60 minutes.
Is set to a melt flow index (M
2: g / 10 minutes) and expressed in%.

Melt Retention (%) = (M1 / M2) × 100 (7) Odor 50 g of pellets are put in a 100 ml glass container with a stopper tightly closed, left at a temperature of 70 ° C. for 60 minutes, immediately taken out, and taken out according to the following criteria. An odor sensory test was performed. ◎: No odor ○: Slight odor but not unpleasant ×: Obvious odor In addition, the active polymer solution of the block copolymer used in Examples was produced as follows. The weight ratio of the polymer to the solvent in the resulting polymer solutions of the block copolymers (A) to (D) was 1: 3. [Block copolymer (A)] Under a nitrogen gas atmosphere, n was added to a cyclohexane solution containing 15 parts by weight of styrene.
0.1 parts by weight of butyllithium were added,
After polymerization for 1 minute, cyclohexane containing 70 parts by weight of 1,3-butadiene was continuously added, and the mixture was heated at 70 ° C. for 60 minutes.
Polymerized for minutes. Next, a cyclohexane solution containing 15 parts by weight of styrene was added, and polymerization was performed at 70 ° C. for 20 minutes. The resulting polymer was prepared from AB- having a styrene content of 30% by weight.
It was a block copolymer having the A structure. [Block Copolymer (B)] Under a nitrogen gas atmosphere, 0.11 part by weight of n-butyllithium is added to a cyclohexane solution containing 15 parts by weight of 1,3-butadiene and 20 parts by weight of styrene. After polymerizing for minutes,
Further, cyclohexane containing 45 parts by weight of 1,3-butadiene and 20 parts by weight of styrene was added, and polymerization was performed at 70 ° C. for 40 minutes. The obtained polymer was a block copolymer having a BABA structure having a styrene content of 40% by weight. [Block copolymer (C)] Under a nitrogen gas atmosphere, n was added to a cyclohexane solution containing 30 parts by weight of styrene.
-Butyl lithium at 0.08 parts by weight,
After polymerizing for 0 minutes, cyclohexane containing 40 parts by weight of 1,3-butadiene was added and polymerized at 70 ° C. for 40 minutes. Thereafter, a cyclohexane solution containing 30 parts by weight of styrene was further added, and polymerization was performed at 70 ° C. for 30 minutes. The obtained polymer was a block copolymer having an ABA structure with a styrene content of 60% by weight. [Block copolymer (D)] Under a nitrogen gas atmosphere, 0.06 parts by weight of n-butyllithium was added to a cyclohexane solution containing 9 parts by weight of styrene and 0.06 parts by weight of tetramethylethylenediamine, and added at 150C at 150C. After polymerizing for 1 minute, cyclohexane containing 82 parts by weight of 1,3-butadiene was added and polymerized at 70 ° C. for 40 minutes. Thereafter, a cyclohexane solution containing 9 parts by weight of styrene was further added, and polymerization was performed at 70 ° C. for 15 minutes. The obtained polymer was a block copolymer having an ABA structure with a styrene content of 18% by weight. Next, the block copolymer obtained above was treated with Ti as described in JP-A-59-133203.
The mixture was hydrogenated with a system hydrogenation catalyst to obtain a hydrogenated block copolymer having a hydrogenation ratio of a butadiene portion of 95%.

[0037]

Example 1 After polymerization of the block copolymer (A), the reaction was terminated by adding 0.9 times equivalent of ethanol to n-butyllithium in a polymerization vessel. Thereafter, 0.02 parts by weight of water was added to 100 parts by weight of the polymer while transferring the polymerization solution from the polymerization vessel to another reaction tank, and then the pH of the solution was adjusted to 7.2 by adding carbon dioxide gas. did. Polymer 1 was added to this solution.
2- [1- (2-hydroxy-3,
5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate (hereinafter referred to as Stabilizer A
0.7 parts by weight of n-octadecyl 3- (3,
0.3 parts by weight of 5-di-t-butyl-4-hydroxyphenyl) propionate (hereinafter, referred to as stabilizer B1),
2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite (hereinafter referred to as stabilizer C1)
Was added and uniformly mixed, and kept at 80 ° C. for 48 hours with stirring. Then, the temperature of the polymer solution was raised to 170 ° C. through a heat exchanger, and the solvent was removed with a flash concentrator. Some were flash evaporated. The temperature at the outlet of the concentrator dropped to 100 ° C. and the concentration was 50% by weight.

The concentrated polymer solution was heated again to 160 ° C. through a heat exchanger and fed to a twin screw extruder to remove the solvent. The extruder used was a mesh type co-directional two-axis three-stage vent extruder with a screw outside diameter of 65 mm and L / D = 40 having a rear exhaust zone, and a gear pump was mounted between the screw tip and the die. .
The operating conditions were a screw rotation speed of 120 rpm, a polymer extrusion rate of 80 kg / hour, and water flowing between the second exhaust zone and the last exhaust zone (third exhaust zone).
It was added at a ratio of 1 part by weight to 00 parts by weight using a plunger type metering pump.

[0039] The solvent recovery in the rear exhaust zone of Example 1 was 82
% By weight, and the amount of residual cyclohexane of the obtained polymer was 1%.
At 400 ppm, the water content was 450 ppm and the polymer temperature at the exit of the die was 195 ° C. Further, the residual ratio of the added stabilizer was 95% by weight or more, and volatilization of the stabilizer was not recognized. Table 1 shows the results such as the quality of the obtained polymer.

[0040]

Examples 2 to 4 Block copolymers (B), (C),
In the solution of (D), 0.8 equivalent of ethanol was added to (B) with respect to n-butyllithium, 0.7 equivalent of methanol was added to (C) with respect to n-butyllithium, and 1 equivalent was added to (D). .3
The reaction was stopped by adding double equivalents respectively to the polymerization vessel. Table 2 shows the subsequent process conditions. The stabilizer B2 in Table 2 is 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, and the stabilizer C2 is 2-[[2,4 , 8,10-Tetrakis (1,1-dimethylethyl) dibenzo [d,
f] [1,3,2] dioxaphosphefin-6-yl] oxy] -N, N-bis [2-[[2,4,8,1
0-tetrakis (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphefine-
6-yl] oxy] -ethyl] -ethanamine, stabilizer C3 is 2,4-bis [(octylthio) methyl] -o-
Cresol.

The process conditions, extruder specifications, etc. of the parts not described in Table 2 were the same as in Example 1. The water content of all the obtained polymers was 450 ppm or less, the residual ratio of the stabilizer was 95% by weight or more, and no volatilization of the stabilizer was observed. Table 1 shows the results such as the quality of the obtained polymer.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

Example 5 As a result of measuring the quality and the like of the polymer at the time when 15 batches were repeated in the same manner as in Example 1, the gel amount was と.

[0045]

Comparative Examples 1 to 4 Table 3 shows the process conditions after the polymerization of the block copolymer (A) and the addition of ethanol to the polymerization reactor at 0.9 equivalents of n-butyllithium. Other process conditions, extruder specifications, and the like of the parts not described in Table 3 are the same as those in Example 1. The water content of all the obtained polymers was 450 ppm or less, and no volatilization of the stabilizer was observed. Table 4 shows the results such as the quality of the obtained polymer.

[0046]

[Table 3]

[0047]

[Table 4]

[0048]

Comparative Example 5 After the polymerization of the block copolymer (A), ethanol as a reaction terminator was not added to the polymerization reactor, but the polymerization solution was transferred from the polymerization reactor to another reaction vessel, and then ethanol was added. A polymer was obtained in the same manner as in Example 1. As a result of measuring the quality and the like of the polymer at the time when this method was repeated for 15 batches, a mixture of a large number of gels which were considered to have occurred in the polymerization vessel when the gel amount was x was recognized.

[0049]

COMPARATIVE EXAMPLE 6 In Example 2, the polymer temperature of the extruder was 162 ° C. in the first exhaust zone and 20 in the second exhaust zone.
7 ° C, 215 ° C at the third exhaust zone, 228 ° C at the die exit
A polymer was obtained in the same manner as in Example 2, except that The obtained polymer had a gel amount of x, an odor of x, a low molecular ratio of 3.4%, and a high molecular ratio of 2.8%.

[0050]

According to the present invention, when a block copolymer having a relatively low vinyl aromatic hydrocarbon content or a hydrogenated product thereof is directly desolvated using a twin-screw vent extruder, addition of alcohol and water Addition, adjustment of solution PH, stabilizer,
By specifying the structure of the twin-screw vent extruder and its conditions, a block copolymer or a hydrogenated product thereof having less gel in pellets, excellent color tone and transparency, and having good processing stability can be obtained. Can be recovered.

The block copolymer or its hydrogenated product obtained by the present invention is widely used in the fields of footwear, plastic modification, asphalt, and adhesiveness, utilizing its features.
In particular, since the block copolymer or its hydrogenated product obtained by the method of the present invention has a small amount of gel, heat-resistant deterioration (melt retention) of a spiral-coated adhesive or a blend with GPPS, etc. And can be suitably used in the field of thin sheets or films.

[Brief description of the drawings]

FIG. 1 is an example of a flow diagram of a solvent removal process in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Extruder 2 2-axis endless screw 3 Pressure and supply speed control valve 4 Supply hopper 5 Rear exhaust zone 6 Exhaust zone 7 Inlet for introducing water to promote solvent removal 8 Gear pump 9 Die 10 Cutter

Claims (1)

[Claims] 1. A hydrocarbon solvent having a vinyl aromatic hydrocarbon content of 10% by weight or more and less than 65% by weight obtained by polymerizing a conjugated diene and a vinyl aromatic hydrocarbon with an organolithium compound as an initiator. In obtaining the block copolymer or its hydrogenated product by directly removing the solvent from the solution of the block copolymer or its hydrogenated product,
(1) a step of adding an alcohol to an active polymer solution of a block copolymer or a hydrogenated product thereof into a polymerization vessel; and (2) a step of adding a block copolymer to the solution of the block copolymer or a hydrogenated product thereof. Or, with respect to 100 parts by weight of the hydrogenated product, 0.0
After adding 0.5 to 0.1 parts by weight of water, carbon dioxide is added to adjust the pH of the solution to a range of 6.5 to 8.5, or after adding carbon dioxide, 0.005 to 0 Adjusting the pH of the solution to 6.5 to 8.5 by adding 1 part by weight of water; (3) adding the block copolymer or the hydrogenated product thereof to the block copolymer or the hydrogenated solution thereof; A) 2- [1- (2-Hydroxy-3,5) based on 100 parts by weight of the hydrogenated product.
-Di-t-pentylphenyl) ethyl] -4,6-di-
0.03 to 2 parts by weight of t-pentylphenyl acrylate, B) 2-t-butyl-6- (3-t-butyl-2-
Hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, n-octadecyl 3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionate, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6 -Tris (3,5-di-t-butyl-4-hydroxybenzyl)
Benzene, 2,4-bis- (n-octylthio) -6
(4-hydroxy-3,5-di-t-butylanilino)
0.03 to 2 parts by weight of at least one of -1,3,5-triazine, C) 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, 2-[[2,
4,8,10-tetrakis (1,1-dimethylethyl)
Dibenzo [d, f] [1,3,2] dioxaphosphefin-6-yl] oxy] -N, N-bis [2-
[[2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphefin-6-yl] oxy] -ethyl] -ethanamine, 2,4-bis [(octylthio) methyl]-
adding 0.01 to 2 parts by weight of at least one of o-cresol as a stabilizer, (4) heating the solution of the block copolymer or a hydrogenated product thereof to a temperature of 130 to 180 ° C. in advance, It was introduced into the feed hopper of the endless screw to create a pressure reduction in the feed zone, and after 75-95% by weight of the solvent was removed in a short time, it was reheated by heat transfer from the barrel and rotation of the screw. ２2% by weight of water is injected into at least one point between the exhaust zones,
After removing 25% by weight of the polymer temperature in all zones of the exhaust zone located in front of the feed hopper at 150-200 ° C., it was introduced into the die located downstream and was placed with a cutter located immediately after the die. By cutting,
A step of obtaining a pellet-like form, a method of recovering a block copolymer or a hydrogenated product thereof.