JPH02185503A - Dehydration of polymer - Google Patents

Abstract

PURPOSE:To dehydrate a polymer efficiently and smoothly by dehydrating a specified crumb under such a condition that the distance between adjacent dehydration slits of a screw extruder type squeeze dehydrator is kept in a specified range. CONSTITUTION:When a crumb obtd. by removing a solvent by means of steam stripping of a soln. of a conjugated diene-vinyl arom. hydrocarbon block copolymer or a hydrogenated product thereof is dehydrated by means of a screw extruder type squeeze dehydrator, the aimed polymer with a water content of 20wt.% or less can be obtd. by keeping the distance between adjacent dehydration slits in a range of 0.06-1.0mm. Said block copolymer exhibits characteristics as a thermoplastic elastomer when the content of the vinyl arom. hydrocarbon is 60wt.% or lower, pref. 55wt.% or lower while it exhibits characteristics as a thermoplastic resin when the content of the vinyl arom. hydrocarbon is higher than 60wt.%, pref. 65wt.% or higher.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for removing the solvent by steam stripping a solution of a block copolymer of a conjugated diene and a vinyl aromatic hydrocarbon or a hydrogenated product thereof. This invention relates to a method for efficiently dehydrating crumb-like polymers obtained by

[Conventional technology]

Block copolymers consisting of conjugated dienes and vinyl aromatic hydrocarbons are transparent and have the same properties as vulcanized natural rubber or synthetic rubber without vulcanization when the vinyl aromatic hydrocarbon content is relatively low. Because it has elasticity at room temperature and processability similar to thermoplastic resins at high temperatures, it is widely used in the fields of footwear, plastic modification, asphalt, adhesives, etc. In addition, when the vinyl aromatic hydrocarbon content is relatively high, a thermoplastic resin that is transparent and has excellent impact resistance can be obtained, so its usage has increased in recent years, mainly in the food packaging container field, and its applications have also expanded. It is becoming more diverse.

When producing these copolymers, polymerization is usually carried out in a hydrocarbon solvent that is inert to the catalyst, and the resulting copolymers are either uniformly dissolved in the solvent or in a suspended state. To obtain this, the copolymer and the solvent are separated,
A step is required to recover the copolymer. There are various methods for separating the copolymer and the solvent.
As a method, a steel stripping method is known in which a polymer solution is injected into hot water, the solvent is distilled together with water vapor, and the polymer is precipitated in the form of crumbs. For example,
457 Publication, Special Publication No. 55-7460, Special Publication No. 1987
5-22489, JP 56-35687, JP 58-10411, JP 58-114
A method described in Publication No. 47 and the like is known. The water content of the Kura J-shaped polymer obtained by this method is removed by dehydration and drying. Dehydration and drying methods include, for example, Japanese Patent Application Laid-open No. 559-535 (No.
A method described in Japanese Patent No. 614 and the like is known.

(Problem to be Solved by the Invention) In the above-mentioned dehydration/drying method, as a dewatering device for the water-containing crumb in the dehydration step, a compression water squeezer such as a roll, a Banbury type dehydrator, or a screw extruder type squeezer is generally used. Among these dehydrators, the screw extruder type squeeze dehydrator is generally used because it is suitable for continuous production.The screw extruder type squeeze dehydrator is
A slit is provided to drain the squeezed water out of the device. However, when dehydrating the hydrous crumb of a block copolymer of a conjugated diene and a vinyl aromatic hydrocarbon using such a conventional device, since the copolymer is thermoplastic, it becomes plastic due to the heat generated at the constriction section. The copolymer is squeezed out from the slit gap that was originally used to drain water.
There was a problem in that the gap was blocked, resulting in poor dehydration and normal dehydration operation could not be continued for a long period of time.

[Means to solve the problem]

The present inventors have described a method for dehydrating a polymer using a screw extruder type squeeze dehydrator as a dehydrating device for a hydrous polymer.
As a result of intensive study to solve the two drawbacks of the conventional technology,
It was discovered that the purpose could be achieved by setting the slit interval in the slit section for dehydration within a specific range,
The invention has been completed.

That is, the present invention involves steam-stripping a solution of a block copolymer of a conjugated diene and a vinyl aromatic hydrocarbon or its hydrogenated product to remove the solvent, and then dehydrating the crumb obtained by removing the solvent using a screw extruder. When dewatering in a machine, the slit interval in the dewatering slit section is set to 0.06 to 1. The present invention relates to a method for dehydrating a block copolymer or a hydrogenated product thereof, characterized in that a polymer having a water content of 20% or less is obtained by controlling the water content to a range of 0 mm.

The present invention will be explained in detail below.

The vinyl aromatic hydrocarbon content of the block copolymer of a conjugated diene and a vinyl aromatic hydrocarbon used in the present invention or its hydrogenation product is generally 5 to 95% by weight, preferably 1
It is 0 to 90% by weight.

As a method for producing block copolymers, for example,
6-19286, Japanese Patent Publication No. 17979, Japanese Patent Publication No. 46-32415, Japanese Patent Publication No. 49-369
57 Publication, Special Publication No. 48-2423, Special Publication No. 4L
-4106, JP 56-28925, JP 51-49567, JP 59-16651
Examples include methods described in Japanese Patent Application Laid-open No. 8, Japanese Patent Application Laid-open No. 186577/1983, and the like. By these methods, block copolymers can be obtained using the general formula % (%) (In the above formula, A is a polymer block mainly composed of vinyl aromatic hydrocarbons, and B is a polymer block mainly composed of conjugated dienes. (The boundary between A block and 13 bronc does not necessarily need to be clearly distinguished. Also, n is an integer of 1 or more.) Or -Sailor% formula% (In the above formula, A and B are and X is the residue of a coupling agent such as silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, polyhalogenated hydrocarbon, carbonic acid ester, polyvinyl compound, or the initiation of a polyfunctional organolithium compound. m and n are integers of 1 or more.

In the above formula, the polymer block mainly composed of vinyl aromatic hydrocarbons refers to a copolymer block of vinyl aromatic hydrocarbons and conjugated diene containing 50% by weight or more of vinyl aromatic hydrocarbons and/or vinyl This refers to an aromatic hydrocarbon homopolymer block, and a polymer block mainly composed of conjugated diene refers to a copolymer block of a conjugated diene and a vinyl aromatic hydrocarbon containing a conjugated diene in an amount exceeding 50% by weight. Or a conjugated diene homopolymer block.

The vinyl aromatic hydrocarbons in the copolymer block may be uniformly distributed or tapered. Further, in the copolymer portion, a plurality of portions in which vinyl aromatic hydrocarbons are uniformly distributed and/or portions in which vinyl aromatic hydrocarbons are distributed in a tapered manner may coexist. The block copolymer used in the present invention may be any mixture of block copolymers represented by the above-mentioned symbols.

The block copolymer thus obtained exhibits properties as a thermoplastic elastomer when the content of vinyl aromatic hydrocarbon is 60% by weight or less, preferably 55% by weight or less,
When the vinyl aromatic hydrocarbon content exceeds 60% by weight, preferably 65% by weight or more, it exhibits properties as a thermoplastic resin.

Vinyl aromatic hydrocarbons used in the method of the present invention include styrene, 0-methylstyrene, p-methylstyrene, p-methylstyrene,
Examples include -tert-butylstyrene, 1,3 dimethylstyrene, α-methylstyrene, vinyl-1-7crene, and vinylanthracene, among which styrene is particularly common.

These may be used not only alone, but also as a mixture of two or more.

The conjugated diene used in the present invention is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene).
, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, etc., and particularly common ones include 1,3-butadiene and isoprene. These may be used not only alone, but also as a mixture of two or more. Hydrocarbon solutions used in the production of block copolymers include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, octane, isooctane, etc., cyclobencune, methylcyclopencune, cyclohexane, methylcyclohexane, ethylcyclohexane, etc. Alicyclic hydrocarbons or aromatic hydrocarbons such as Hensen, toluene, ethyl Hensen, and xylene can be used.

These may be used not only alone, but also as a mixture of two or more. It is also used in the production of block copolymers. Organolithium compounds are organic monolithium compounds in which one or more lithium atoms are bonded in the molecule, such as ethyllithium, n-propyllithium, isopropyllithium J.
2, n-butyllithium, 5ec-butyllithium, t
Examples include er t-butyl lithium, hexamethylene dilithium, butadienyl dilithium, and isoprenyl dilithium. These may be used not only alone, but also as a mixture of two or more.

In the production of the block copolymer used in the present invention, the polymerization rate must be adjusted, the microstructure (cis, trans, vinyl ratio) of the polymerized conjugated diene moiety must be changed, and the reactivity ratio of the conjugated diene and vinyl aromatic hydrocarbon must be adjusted. Polar compounds and randomizing agents can be used for purposes such as adjustment of . As polar compounds and randomizing agents, ethers, amines,
Examples include thioethers, phosphoramides, alkyl hanzene sulfonates, and potassium or sodium alkoxides. Examples of suitable ethers are dimethyl ether, diethyl ether, diphenyl ether and hytetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether. Examples of amines include tertiary amines such as trimethylamine, triethylamine, tetramethylethylenediamine,
Cyclic tertiary amines and the like can also be used. Phosphines and phosphoramides include triphenylphosphine and hexamethylphosphoramide. Randomizing agents include potassium or sodium alkylhenzenesulfonate, potassium or sodium butoxide, and the like.

In the present invention, the polymerization temperature for producing the block copolymer is generally 110°C to 150°C, preferably 4°C.
0°C to 120°C. The time required for polymerization varies depending on the conditions, but is usually within 48 hours, particularly preferably 0.5 to 10 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 within a pressure range sufficient to maintain the monomer and solvent in a liquid phase within the above polymerization temperature range. Furthermore, care must be taken to avoid contamination of the polymerization system with impurities that would inactivate the catalyst and living polymer, such as water, oxygen, carbon dioxide, and the like.

The number average molecular weight of the block copolymer thus obtained is generally 10.000 to 1.000. ．． 000,000, preferably 20,000 to 800,000, more preferably 30,000 to 500,000. The amount of hydrocarbon in the liquid of the 1-Cock copolymer is 50 to 2000 parts by weight per 100 parts by weight of the polymer. In addition, depending on the properties of the block copolymer, the block copolymer may be insoluble in the hydrocarbon agglomerate! ! ! , may be obtained in a cloudy state, but in the present invention, these are also referred to as block copolymer solutions.

The block copolymer used in the present invention may be a terminally modified block copolymer in which a polar group-containing atomic group is bonded to at least one polymer chain terminal of the polymer. Here, the polar group-containing atomic group refers to an atomic group containing at least one atom selected from nitrogen, oxygen, silicon, phosphorus, sulfur, and tin.

Specifically, carboxyl group, carbonyl group, thiocarbonyl group, acid halide group, acid anhydride group, carboxylic acid group, thiocarboxylic acid group, aldehy 1ζ group, 1,000 aldehyde group, carboxylic acid ester group, amide group, Sulfonic acid group, sulfonic acid ester group, phosphoric acid group, phosphoric acid ester group, amino group, imino group, nitrile group, pyridyl group, quinoline group, epoxy group, thioepoxy group, sulfone group,
Examples include atomic groups containing at least one polar group selected from isocyanate groups, isothionate groups, halogenated silicon groups, alkoxysilicon groups, halogenated tin groups, alkyltin groups, phenyltin groups, and the like. More specifically, the terminal-modified block copolymer described in Japanese Patent Application No. 1983-224806 can be used.

In addition, in the present invention, the block copolymer or modified pro-7 copolymer obtained above can be partially or selectively hydrogenated by hydrogenation reaction ()) (primary addition reaction). Can be done. The hydrogenation rate can be selected arbitrarily, and in order to improve thermal deterioration while maintaining the properties of an unhydrogenated polymer, 3% or more of aliphatic double bonds based on conjugated dienes, It is ill recommended to hydrogenate 80% or more, preferably 5% or more, and less than 75%, and hydrogenate 80% or more, preferably 90% or more in order to improve heat deterioration resistance and weather resistance. Ru. In this case, the aromatic double bond based on the vinyl aromatic compound copolymerized with the polymer block A mainly composed of a vinyl aromatic compound and, if necessary, the polymer block B mainly composed of a conjugated diene compound. Although there is no particular restriction on the water addition rate, it is preferable that the hydrogenation rate is 20% or less.

The amount of unhydrogenated aliphatic double bonds contained in the hydrogenated block copolymer can be easily determined using an infrared spectrometer, nuclear magnetic resonance apparatus, or the like. Catalysts used in the hydrogenation reaction include (1) supported heterogeneous catalysts in which metals such as Ni, pt, and PdRu are supported on carbon, silica, alumina, diatomaceous material, etc., and (2) Ni,
So-called Ziegler type catalysts using organic acid salts such as Co, Fe, Cr or acetylacetone salts and reducing agents such as organic Ap, or so-called organic complex catalysts such as organometallic compounds such as I+', Rt+, Rh, etc. Homogeneous catalysts are known. A specific method is described in Japanese Patent Publication No. 42-8704, +4. ! l- Publication No. 4B6636, or JP-A No. 59-133203, JP-A No. 1-2201
According to the method described in Japanese Patent No. 47, hydrogenation is performed in an inert solvent in the presence of a hydrogenation catalyst to obtain a hydrogenated product, and the hydrogenated block copolymer used in the present invention can be synthesized. At this time, the hydrogenation rate of aliphatic double bonds based on the conjugated diene compound in the block copolymer can be controlled to any value by adjusting the reaction temperature, reaction time, hydrogen supply amount, catalyst amount, etc.

From the solution of the block copolymer or its hydrogenated product obtained as described above, the solvent is removed by a steam stripping method to obtain a slurry in which the polymer is dispersed in crumbs in water. The specific treatment method in this steam stripping method is not particularly limited and may be any suitable conventionally known method. A crumbling agent may be used during steam stripping, and anionic surfactants, cationic surfactants, and nonionic surfactants are generally used as such crumbling agents. These surfactants are generally added at 0.1 to 3000 ppm to the water in the stripping zone.

In addition to these surfactants, Li, Na, Mg,
Ca, A1. Water-soluble salts of metals such as , Zn, etc. can also be used as crumb dispersion aids.

Next, the moisture-containing block copolymer or its hydrogenated crumb obtained above is dehydrated to reduce the moisture content to 20% by weight or less, preferably 1 to 15% by weight, more preferably 2 to 10% by weight.
% by weight (hereinafter this process will be referred to as the dehydration process). In this dehydration step, a multi-screw extruder type squeeze dehydrator with one or two wheels or the like is used in the present invention. Such a dehydrator is preferable in terms of dewatering efficiency and workability. If the water content of the polymer dehydrated in the dehydration step exceeds 20 parts, it is not preferable because drying in the next drying step will be insufficient.

In addition, in order to reduce the water content of the dehydrated polymer to less than 1% by weight in the dehydration process, the dehydration treatment time may be too long, the polymer may gel due to the shearing force of the water squeezer, or the shirt may be decomposed. Therefore, it is generally preferable that the water content in the polymer after dehydration in the dehydration step is 1 to 20% by weight. In addition, the slurry crumb obtained in the steam stripping process is cut in advance using a rotary screen, a vibrating screen, a centrifugal dehydrator, etc. until the water content is 35 to 60%, and then introduced into a compressed water squeezer. is preferable.

The greatest feature of the present invention is that in the dewatering process, the slit interval in the slurry I section for dewatering is set to 0.06 to 1.
．． 0 mm, preferably 0.07 to 0.5 mm, more preferably 0.08 to 0.0 mm. ．． It is to be within the range of 3 mm.

If the slit interval is less than 0.06Nr1, the dehydration efficiency is poor and a polymer with a water content of 20% by weight or less cannot be obtained.

Moreover, if the slit interval exceeds 1.0 mm, it is not preferable because the polymer leaks violently from the surin [interval], dehydration efficiency decreases, and polymer loss increases. There are no particular restrictions on the number or length of dehydration slits, but those with a length of 1 to 3 and a length L/I) of 0.5 to 5 are generally used.

Next, the dehydrated polymer or hydrogenated product thereof is dried in a drying device (hereinafter, this step is referred to as a drying step). As the drying device, a screw extruder type or kneader type dryer, an expander dryer, a hot air dryer, etc. are used, and the water content in the dried polymer is generally less than 1% by weight, preferably 0.5%. Weight% or less, more preferably 01
It is 1% by weight or less. A particularly suitable dryer is a multi-screw hent extruder type dryer, such as a single screw or twin screw dryer.
I) (screw length/diameter) of 10 to 40 can be used. If the water content in the drying step is 1% by weight or more, it is not preferable because the polymer may foam during molding or cause appearance defects such as silver. In the drying process, the polymer can be obtained in the form of foamed crumbs, granules or powder, or in the form of strands or pellets.

In the present invention, the dehydration step and the first step of drying can also be carried out in an apparatus in which a dehydrator and a dryer are integrated. A suitable device for such a device is a two-shaft or more device having at least one, preferably 2 to 4 slits for dehydration and at least one, preferably 2 to 4 hent portions for degassing. Examples include the Ghent extruder. The Hendt extruder having such a structure preferably has an L/D of about 15 to 50, and the interlocking structure of the screws can be either meshing or non-meshing, and the direction of rotation can be either in the same direction or in different directions. But that's fine. The screw rotation speed, cylinder heating temperature, and pressure in the Ghent section of such a Ghent extruder are selected taking into account extrusion capacity, polymer properties (viscosity and thermal stability), product quality, etc., but in general, Screw rotation speed: 20 to 500 revolutions/min, preferably 30 to 400 revolutions/min, cylinder temperature: 100 to 300°C, preferably 130 to 260°C, pressure in the hent section: atmospheric pressure to 10m
m1H absolute pressure, preferably from 500 to 50 mm) 1g absolute pressure.

In the method of the present invention, various additives can be added to the polymer depending on the purpose. For example, softeners such as oil, plasticizers, antistatic agents, lubricants, ultraviolet absorbers, flame retardants, pigments, inorganic light agents, organic fibers/inorganic fibers, auxiliary agents such as carbon blank, other thermoplastic resins, etc. can be used as an additive.

These additives may be added to the polymer solution, during the dehydration step and/or drying step, or after the drying step.

After the polymer dehydrated by the method of the present invention is dried,
Can be used as a wide variety of molded products such as films, injection molded products of various shapes, blow molded products, pressure molded products, vacuum molded products, etc., as well as modifiers for various thermoplastic resins, materials for footwear, and adhesives. , adhesive materials, asphalt modifiers, wire and cable materials, vulcanized rubber materials, vulcanized rubber modifiers,
It can be used as a material for home appliances, automobile parts, industrial parts, household goods, toys, etc.

〔Example〕 EXAMPLES The present invention will be explained in more detail with reference to Examples below.

The block copolymers used in the examples were produced as follows. Obtained block copolymers (8) to (C)
The weight ratio of polymer to solvent in each polymer solution is 1.
: It was 3.

[Block copolymer (A)]

In a nitrogen gas atmosphere, 0.08 parts by weight of n-butyllithium was added to a cyclohexane solution containing 30 parts by weight of styrene and 0.3 parts by weight of tetrahyfuran, and the mixture was heated at 70°
After polymerization at C for 1 hour, a cyclohexane solution containing 1.3 to 20 parts by weight of butadiene and 50 parts by weight of styrene was further added and polymerized at 70°C for 2 hours. The obtained polymer was a block copolymer having an ABA structure with a styrene content of 80% by weight.

[Block copolymer (B)]

In a nitrogen gas atmosphere, 0.15 parts by weight of n-butyllithium was added to a cyclohexane solution containing 75 parts by weight of styrene, and after polymerization at 70°C for 1 hour, a cyclohexane solution containing 25 parts by weight of 1,3-butadiene was added. was added and polymerized for 2 hours at 70"C. Thereafter, 5 parts by weight of evaxated dog bean oil was added to obtain a block copolymer with a radical structure having a styrene content of 75% by weight.

[Block copolymer (C)] In a nitrogen gas atmosphere, n-hexane solution containing 15 parts by weight of 1,3-butadiene and 20 parts by weight of styrene was
- After adding 0.11 parts by weight of butyllithium and polymerizing at 70°C for 2 hours, further adding an n-hexane solution containing 45 parts by weight of 1.3-butadiene and 20 parts by weight of styrene, and polymerizing at 70°C for 2 hours. Polymerized for hours. The obtained polymer was a block copolymer having a B-A-B-A structure with a styrene content of 40% by weight. (Block copolymer (D)) In a nitrogen gas atmosphere, 0.1 part by weight of n-butyllithium was added to a cyclohexane solution containing 10 parts by weight of styrene, and after polymerization at 70°C for 1 hour, isoprene 8
Add a cyclohexane solution containing 0 parts by weight and heat to 70°C.
Polymerization was carried out for 2 hours. Thereafter, a cyclohexane solution containing 10 parts by weight of styrene was further added and polymerized at 70°C for 1 hour. The obtained polymer is a block copolymer having an A-B-Δ structure with a styrene content of 20% by weight (polymer concentration of 20% by weight).
weight%).

[Block copolymer (E)]

In a nitrogen gas atmosphere, 0.06 parts by weight of n-butyllithium was added to a cyclohexane solution containing 15 parts by weight of styrene and 0.06 parts by weight of tetramethylethylenediamine, and after polymerization at 70°C for 1 hour, 1.3 parts by weight of n-butyllithium was added. - 70% by adding a cyclohexane solution containing 70 parts by weight of Bukujun
Polymerization was carried out at °C for 2 hours. Thereafter, a cyclohexane solution containing 15 parts by weight of styrene was further added and polymerized at 70°C for 1 hour. The obtained polymer was an A-BA tank structural block copolymer with a styrene content of 30% by weight.

Next, the block copolymer obtained above was
A hydrogenated block copolymer with a hydrogenation rate of 95% in the butadiene portion (
A polymer concentration of 15% by weight was obtained.

[Block copolymer (F)]

In a nitrogen gas atmosphere, n-hexane solution containing 15 parts by weight of 3-butadiene and 20 parts by weight of styrene was
- After adding 0.07 parts by weight of butyllithium and polymerizing at 70°C for 2 hours, an n-hexane solution containing 15 parts by weight of 1,3-butadiene and 50 parts by weight of styrene and 0.02 parts by weight of n-butyllithium. was added and polymerized at 70°C for 2 hours. The obtained polymer was a mixture consisting of a block copolymer with a B-A-B-A structure and a block copolymer with a B-A structure, with a styrene content of 70% by weight, and the obtained polymer solution ( The polymer concentration (30% by weight) was in suspension.

Example 1 and Comparative Example 1.2 Water was added to a cyclohexane solution of block copolymer (A) to stop the reaction, and after thoroughly mixing to stop the reaction, , 0.5 parts by weight of octadecyl-3(3+5-di-tert-butyl-4-hydroxyphenyl)propionate and 0.5 parts by weight of tris(2,4-di-tert-butylphenyl)phosphite were added and mixed thoroughly. did.

When steam stripping the above block copolymer, α-(pnonylphenyl) is used as a crumbling agent.
A mixture of dihydrodiene phosphate and monohydrodiene phosphate of -ω-hydroxypoly(oxyethylene) (the average number of oxyethylene units in poly(oxyethylene) is 9 to 10) is added to the water in the stripping zone. The solvent was removed at a temperature of 90-98°C. The concentration of polymer crumb in the slurry in the solvent removal tank was about 5% by weight.

Next, the crumb-like block copolymer (A
) was sent to a rotary screen to obtain a water-containing crumb with a water content of about 45% by weight.

This water-containing crumb was sent to a single screw extruder type water squeezer having one slit with the slit spacing shown in Table 1 to obtain a dehydrated polymer (dehydration step). Table 1 shows the measurement results of the water content in the obtained polymer. Thereafter, the polymer obtained above was fed to a two-screw one-stage Ghent extruder,
Cylinder temperature 200°C, screw rotation speed 200
It was extruded and dried at rotation/minute and vent pressure of about 200 ninl1g absolute pressure (drying step). The polymer obtained in the form of a strand from the tip of the extruder was cut into a pellet shape using a cutter.

Table 1 shows the measurement results of the water content in the dried polymer.

Examples 2 to 4 Block copolymers [D],
(E) and (F) were dehydrated and dried.
Shown in the table.

(Leaving space below) Table 1 Example 5 Water was added as a reaction terminator to a cyclohexane solution of Zoroku copolymer (B), and the reaction was stopped by mixing thoroughly.
After adding 2- to 100 parts by weight of block copolymer,
tert-butyl-6-(3Lert-butyl-2-
H1: VJxy5-methyl-4-methylphenylacryle-140.2 parts by weight, Tris(2,4
-di-tert-butylphenyl) phosphite 0
, 1 part by weight was added and thoroughly mixed.

When steam-ripping the Zoroku copolymer solution described in ``2,'' an average molecular weight of about 220 was used as a crumbling agent.
0. Polyoxyethylene and polyoxyphenate having a polyoxyethylene content of 10 overlapping parts.

A block polymer with lopyrene was used at 5 oppm relative to the water in the stripping zone and the solvent was removed at a temperature of 90-98°C. The concentration of polymer crumb in the slurry in the solvent removal tank was about 3% by weight.

The aqueous dispersion slurry of the Kura L-shaped bronc copolymer (B) obtained above was sent to a rotary screen to obtain a water-containing crumb having a water content of about 45% by weight. This water-containing crumb can be dehydrated and dried in the same device (two-stage slit, two-stage hex)
- A pellet-shaped block copolymer was obtained by feeding the mixture into a twin-screw extruder. The extruder used had a screw diameter of 40 mm, an L/D ratio of 35, and a slit interval of 2.
Those shown in the table were used. The extrusion conditions were: Norinder temperature 200°C, screw rotation speed approximately 200 revolutions/min,
The vent was opened and the pressure was not reduced, and the second vent was vacuum vented to reduce the pressure to 50 + nm 11 g absolute pressure. The water content after dehydration was determined by sampling a portion of the polymer from the first vent. The results are shown in Table 2.

Example 6 and Comparative Examples 3 and 4 The Zoroku copolymer (C) was dehydrated and dried in the same manner as in Example 5, except that surin [the spacing shown in Table 2] was used. The results are shown in Table 2.

(The following is a blank space) [Effects of the Invention] The method of the present invention enables efficient and smooth dehydration of a block copolymer obtained by block copolymerizing a conjugated diene and a vinyl aromatic hydrocarbon or its hydrogenated product. Can be implemented.

Patent applicant: Asahi Kasei Industries, Ltd. Part 2 table

Claims (1)

[Claims] When dehydrating the crumb obtained by removing the solvent by steam stripping a block copolymer of a conjugated diene and a vinyl aromatic hydrocarbon or a solution of its hydrogenated product using a screw extruder type squeezing dehydrator. , the slit interval in the slit part for dehydration is 0.06 to 1.0 mm.
A method for dehydrating a block copolymer or a hydrogenated product thereof, characterized in that a polymer having a water content of 20% by weight or less is obtained by