JPH04175304A - Production of block copolymer - Google Patents

Abstract

PURPOSE:To obtain a block copolymer excellent in heat stability, transparency and color tone a by directly removing the solvent from a solution thereof after adding a specified reaction stopper and then a plurality of specified phenolic compounds to the solution. CONSTITUTION:A process for producing a (hydrogenated) block copolymer of a vinylaromatic hydrocarbon content of 5-95wt.% by polymerizing a conjugated diene (e.g. 1, 3-butadiene) and a vinylaromatic hydrocarbon (e.g. styrene) in the presence of an organolithium compound (e.g. n-butyl- lithium) as an initiator in a hydrocarbon solvent (e.g. cyclohexanone) and directly removing the solvent from the solution, wherein at least one reaction stopper selected from among water, an alcohol, an inorganic acid and an organic acid (e.g. water) is added to the solution, and 0.05-5 pts.wt., per 100 pts.wt. polymer, phenolic compound of the formula (wherein R1 is 5 C or higher alkyl; R2 is 2-4C alkenyl; R3 is 4-22 alkyl or cyclohexyl; and R4 is H or 1-18C alkyl) and 0.01-3 pts.wt., per 100 pts.wt. polymer, phenolic stabilizer other than the above compound is added to the solution.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for directly removing the solvent from a solution of a block copolymer of a conjugated diene and a vinyl aromatic hydrocarbon or a hydrogenated product thereof (hereinafter referred to as the margin). The present invention relates to a method for recovering a polymer or a hydrogenated product thereof having excellent thermal stability, transparency, color tone, and appearance characteristics by combining a specific treatment step and a specific stabilizer.

[Prior Art] A block copolymer composed of a conjugated diene and a vinyl aromatic hydrocarbon is transparent when the vinyl aromatic hydrocarbon content is relatively small, and can be used as a vulcanized natural rubber or vulcanized natural rubber without vulcanization. It has the same elasticity as synthetic rubber at room temperature and the same processability as thermoplastic resin at high temperatures, so it is widely used in the fields of footwear, plastin modification, asphalt, and adhesives. . 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 P!
Since the copolymer is obtained in a cloudy state, a step of separating the copolymer and the solvent and recovering the copolymer is required. There are various methods for separating a copolymer and a solvent, and one known method is to directly heat and concentrate a polymer solution to remove the solvent and recover the polymer.

For example, JP-A-50-76172, JP-A-51-
Rubber, plastic,
Alternatively, a method is described in which the solvent is directly removed from a block copolymer solution using a twin-screw vent extruder.

[Problem to be solved by the invention]

As mentioned above, the method of directly desolventizing the polymer solution by heating and concentrating it has problems in terms of the quality of the recovered polymer, especially its thermal stability and transparency, in addition to the general difficulties in handling high-viscosity liquids at high temperatures. When polymers or hydrogenated products are processed under harsh conditions or recycled using an extruder, gelation or shirt dissolution occurs, resulting in discoloration of the polymer. .

[Means to solve the problem]

The present inventors conducted intensive studies to resolve the above-mentioned drawbacks of the prior art in the method of directly removing solvent from a polymer solution. As a result, the present inventors developed a polymer or When recovering the hydrogenated product, the inventors discovered that the objective could be achieved by combining a specific treatment process and a specific stabilizer, and completed the present invention.

That is, the present invention provides a block having a vinyl aromatic hydrocarbon content of 5 to 95% by weight, obtained by polymerizing a conjugated diene and a vinyl aromatic hydrocarbon in a hydrocarbon solvent using an organolithium compound as an initiator. When obtaining a block copolymer or its hydrogenated product by directly removing the solvent from a solution of the copolymer or its hydrogenated product, (a) Into the solution of the block copolymer or its hydrogenated product, ( a
) water) alcohol (c) inorganic acid (d) organic acid After adding at least one reaction terminator selected from (b) to the solution of the block copolymer or its hydrogenated product (A) the following. 0.05 to 5 parts by weight of a phenolic compound represented by the general formula CI) per 100 parts by weight of the polymer (in the above formula, R is an alkyl group having 5 or more carbon atoms, R
2 is an alkenyl group having 2 to 4 carbon atoms, and R3 is an alkenyl group having 4 to 2 carbon atoms.
2 represents an alkyl group or a cyclohexyl group, and R4 represents hydrogen or an alkyl group having 1 to 18 carbon atoms. ) (B) A method for producing a block copolymer comprising adding 0.01 to 3 parts by weight of a phenolic stabilizer other than the phenolic compound represented by the above general formula CI) to 100 parts by weight of the polymer. .

(Margin below) 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% by weight.
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
Publication No. 57, Special Publication No. 48-2423, Special Publication No. 1977
-4106, JP 56-28925, JP 51-49567, “JP 59-1
Publication No. 66518, Japanese Unexamined Patent Publication No. 60-186577
Examples include the method described in Report 1. these
' method, the block copolymer has the general formula, (A-B
), , A+B-A), , A+A-B),.

(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 1. The boundary between block A and block B does not necessarily have to be clearly distinguished. Further, n is an integer of 1 or more. )? Or the general formula zu((
B-A +r-moTTχ, ((A-B-bmoreTX
1((B-A÷=fl-←=X, ((A-B
-)--A←E "χ (In the above formula, A and B are the same as above, and , a residue of a cambling agent such as a polyvinyl compound, or a residue of an initiator such as a polyfunctional organolithium compound, where m and n are integers of 1 or more.

In the above formula, the polymer block mainly composed of vinyl aromatic hydrocarbons refers to copolymer blocks of vinyl aromatic hydrocarbons and utility dienes containing 50% by weight or more of vinyl aromatic hydrocarbons, and/or or a vinyl aromatic hydrocarbon homopolymer block, and a polymer block mainly containing a symbiotic diene is a copolymer of a conjugated diene containing more than 50% by weight of a conjugated diene and a vinyl aromatic hydrocarbon. It shows a combined block and/or a conjugated diene homopolymer block.

[The vinyl aromatic hydrocarbons in the polymer block may be distributed uniformly or tapered. Further, in the copolymer portions, 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 the block copolymers represented by the general formula 2 above.

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, vinylnaphthalene, and vinylanthracene, among which styrene is particularly suitable for boat fishing.

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-
There are pentagene, 1,3-hexadiene, etc., and 1.3''-butadiene and isoprene are particularly suitable for boat fishing. Good. Hydrocarbon solvents used in the production of block copolymers include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, octane, and isooctane, cyclobencune, methylcyclobencune, cyclohexane, methylcyclohexane, and ethylcyclohexane. Alicyclic hydrocarbons such as, etc., or aromatic hydrocarbons such as benzene, toluene, ethylbenzene, xylene, etc. can be used.

These may be used not only alone, but also as a mixture of two or more. Furthermore, the organic lithium compounds used in the production of the block copolymer are organic monolithium compounds in which one or more lithium atoms are bonded in the molecule, such as ethyllithium, n-propyllithium, isopropyllithium,
n-butyllithium, 5ec-butyllithium, ter
Examples include 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 . Examples of polar compounds and randomizing agents include ethers, amines, thioethers, phosphoramides, alkylbenzene sulfonates, potassium or sodium alkoxides, and the like. Examples of suitable ethers are dimethyl ether, diethyl ether, diphenyl ether and htetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether. As the amines, in addition to tertiary amines such as trimethylamine, triethylamine, and tetramethylethylenediamine, cyclic tertiary amines can also be used. Phosphines and phosphoramides include triphenylphosphine and hexamethylphosphoramide. Potassium or sodium alkylbenzene sulfonate as a randomizing agent;
Examples include potassium or sodium butoxide.

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 may be sufficient to maintain the monomer and solvent in a liquid phase within the above-mentioned polymerization temperature range. Furthermore, care must be taken to avoid contamination of impurities such as oxygen and carbon dioxide gas that would inactivate the catalyst and living polymer in the polymerization system.

The number average molecular weight of the block copolymer thus obtained is generally 10,000 to 1,000,000, preferably 20,000 to soo, and more preferably 30,000 to 500,000. . Also, the amount of hydrocarbon in the block copolymer solution is generally 100% of the polymer.
It is 150 parts by weight to 2000 parts by weight.

Depending on the properties of the block copolymer, the block copolymer may be insoluble in a hydrocarbon solvent and obtained in a suspended state; however, in the present invention, these will also be referred to as a block copolymer solution. .

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, aldehyde group, thioaldehyde group, carboxylic acid ester group, amide group, sulfonic acid group. basis,
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, sulfide group, isocyanate group, isothiocyanate group, silicon halide group, alkoxy silicon group, tin halide group, alkyltin group, phenyltin group Examples include atomic groups containing at least one polar group selected from the following. More specifically, the terminal-modified block copolymer described in Japanese Patent Application No. 60-224806 can be used.

Further, in the present invention, the block copolymer or modified block copolymer obtained above can be partially or selectively hydrogenated by a hydrogenation reaction (hydrogenation reaction). The hydrogenation rate can be selected arbitrarily, and when improving heat deterioration resistance etc. while maintaining the properties of the unhydrogenated polymer, the aliphatic double bond based on the conjugated diene should be 3% or more, 80% or more.
80%, preferably 5% or more, but less than 75% when hydrogenation improves heat deterioration resistance and weather resistance.
% or more, preferably 90% or more is recommended. In this case, the aromatic double bond based on the vinyl aromatic compound copolymerized into 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 limitation on the 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) Ni, Pt, Pd, R
(2) Ni.

Homogeneous catalysts are known, such as the so-called Ziegler type catalyst using an organic acid salt or acetylacetone salt such as Co, Fe, or Cr and a reducing agent such as @A2, or the so-called organic complex catalyst such as an organometallic compound such as Ru or Rh. It is being Specific methods are described in Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, or Japanese Patent Application Laid-open No. 59-133.
203 and JP-A-60-220147, hydrogenation is carried out in an inert solvent in the presence of a hydrogenation catalyst to obtain a hydrogenated product, and the hydrogenated block used in the present invention is Polymers 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.

Next, add (
At least one reaction terminator selected from a) water, alcohol, (c) inorganic acid, and (d) organic acid is added (hereinafter this step will be referred to as the first step). If a reaction terminator is not added in this step, it is not preferable because it may cause a coupling reaction with the stabilizer or cause problems such as poor color tone. In addition to coal, carbon number is 6
-18 higher alcohols and polyhydric alcohols (ethylene glycol, propylene glycol, glycerin, etc.) can be used.

The inorganic acids used in the present invention include acids formed by bonding hydrogen with acid groups containing nonmetals such as chlorine, sulfur, nitrogen, and phosphorus, such as hydrochloric acid, sulfuric acid, nitric acid, boric acid, and phosphoric acid.

Further, the organic acid used in the present invention is an organic compound having acidity in a broad sense, and includes compounds such as carboxylic acid, sulfonic acid, sulfinic acid, and phenol, but preferably an organic compound containing a carboxyl group. The following are preferred.

(1) Fatty acid having 8 or more carbon atoms (2) Rosin acid (3) Oxycarboxylic acid (4) Aromatic carboxylic acid Particularly preferred organic acids are the fatty acids (1), specific examples of which are octylic acid, capric acid, lauric acid, etc. acid, myristic acid, valmitic acid, stearic acid, oleic acid, linoleic acid, lylinic acid, ricinoleic acid, behenic acid, castor hydrogenated fatty acid, tallow fatty acid, or mixtures thereof.

The amount of the reaction terminator used in the first step of the present invention is at least 1 mol, preferably at least 1.5 mol, based on the total amount of the reaction terminating agent based on the Yoiki lithium compound used in the polymerization. When the reaction terminator is water or alcohol, the amount added is:
The amount is preferably 1.5 mol to 1000 mol, more preferably 2.0 mol to 500 mol. When the reaction terminator is an inorganic acid or an organic acid, the amount added is preferably 0.05 to 1.
The amount is 0 mol, more preferably 0.2 to 5 mol. When the amount of the inorganic acid and organic acid added is less than the equivalent mole, it is necessary to use other reaction terminators, preferably water, in combination so that the total amount of the reaction terminator becomes equal to or more than the equivalent mole. If the total amount of the reaction terminator added is less than the equivalent mole, the color tone will be poor, which is not preferable. Particularly suitable reaction terminators in the present invention include water,
At least one selected from inorganic acids and fatty acids.

Next, to the solution of the polymer or its hydrogenated product obtained in the above first step, (A) the phenolic compound shown in (1) above and (B) the phenolic stabilizer are added ( This step will hereinafter be referred to as the second step).

Adding these at this stage is effective in preventing oxidative deterioration and thermal deterioration of the polymer when the solvent is removed in the next step. These may be added to the polymer solution as they are, or may be added after being dissolved in a hydrocarbon solvent.

The phenolic compound used in the present invention is
). In particular, R2 in the present invention is an alkyl group having 5 or more carbon atoms, and R3 is an alkyl group having 4 to 22 carbon atoms or a cyclohexyl group, preferably an alkyl group having 4 to 12 carbon atoms, and more preferably an alkyl group having 5 to 8 carbon atoms. It is an alkyl group. The alkyl group according to the invention is a straight chain or branched alkyl group. When the number of carbon atoms in R1 is 4 or less, the color tone and appearance characteristics are poor, and when the number of carbon atoms in R3 is 3 or less, the thermal stability is poor.

A preferable phenolic compound is one in which R1 is tert-
amyl group, tert-hexyl group, tert-heptyl group, tert-octyl group, R2 is ethynyl group,
Examples include isopropenyl group, propenyl group, isobutenyl group, and butenyl group. Particularly preferred is an ethynyl group. Preferred R3 is tert-butyl group, t
ert-amyl group, tert-hexyl group, tert-
It is a hebutyl group.

Specific examples of the substituent R4 include hydrogen, methyl group, ethyl group, propyl group, and butyl group, with hydrogen, methyl group, and propyl group being particularly preferred.

(Left below) The phenolic compound is preferably 0.1 to 5 parts by weight, preferably 0.1 to 4 parts by weight, based on 100 parts by weight of the polymer.
More preferably, it is used in a range of 0.15 to 3 parts by weight. If the amount of the phenolic compound shown in - Shipura [I] used is less than 0.05 parts by weight, no effect of improving thermal stability is observed, and conversely, even if it exceeds 5 parts by weight, No effect outside the range.

As the phenolic stabilizer, conventionally known ones can be used. Suitable phenolic stabilizers include tetrakis[methylene-3-(3',5'-di-tart-butyl-4
'-Hydroxyphenyl)propionate comethane, 1
．． 3.5-t-dimethyl-2,4゜6-tris(3,5
-tert-butyl-4-hydroxybenzyl)
Benzene, 2,6-di-tert-butyl-4-methylphenol, 4-hydroxy, dimethyl-2,6-di-tert-butylphenol, 2,4-bis-(n-
octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-)riazine, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate , I.
Liethylene glycol bis(3(3tert-butyl-5-methyl-4-hydroxyphenyl)propionate), 1.3.5-)lis-(4-tert-butyl-
3-Hydroxy-2,6-cimitylbenzyl)isocyanuric acid, 2,2'-methylene-bis-(4-methyl-5
-tert-butylphenol), 3.9-bis(2-
(3-(3-tert-butyl-4-hydroxy-5-
methylphenyl)propionyloxy)-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro(5,5)undecane, 4-hydroxymethyl-2,
6-tert-butylphenol, 2,6-tert-butyl-4-ethylphenol, butylated hydroxyanisole, 2,2'-dihydroxy-3,
3'-dicyclohexyl-5゜5'-dimethyl-diphenylmethane, 1.1.3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4
．． 4'-7' tylidene bis(6-tert-butyl-m
-cresol, 4,4'-thiobis[3-methyl-6-
tert-butylphenol], bis(3-cyclohexyl-2-hydroxy-5-methylphenyl)methane,
2.2'-methylenebis(4-ethyl-6-tert-
butyl-phenol), 1,1-bis(2'-methyl-
Examples include 4'-hydroxy-5'-tert-butyl-phenyl)butane. These phenolic stabilizers are used in an amount of 0.01 to 3 parts by weight, preferably 0.05 to 3 parts by weight, and more preferably 0.01 to 3 parts by weight, based on 100 parts by weight of the polymer.
It is used in a range of 1 to 2 parts by weight. Two or more of the above phenolic stabilizers can also be used in combination.

When the amount of phenolic stabilizer used is less than 0.01 part by weight, no improvement effect on thermal stability and color tone was observed;
Even if it exceeds the weight part, the effect beyond the scope of the present invention will not be exhibited.

Furthermore, stabilizers such as sulfur-based stabilizers and phosphorus-based stabilizers that have been conventionally used may be added to the polymer of the present invention.
Specific examples of sulfur-based stabilizers include dilauryl-3,
3'-thiodipropionic acid ester, similystyl-3
, 3'-thiodipropionic acid ester, distearyl-
3,3'-thiodipropionic acid ester, laurylstearyl-3゜3'-thiodipropionic acid ester, pentaerythritol-tetrakis (β-lauryl-thio-propionate), 3,9-bis-(2-dodecyl thioethyl)-2,4,8,10-tetraoxaspiro(5,5)undecane and the like. Specific examples of phosphorus stabilizers include tris(nonylphenyl)phosphite, cyclic neopentanetetrayl bis(octadecylphosphite), tris(2,4-di-t)
er t-butylphenyl) phosphite, 4,4-
Butylidene-bis(3-methyl-6tert-butylphenyl-di-tridecyl)phosphite, 4.4'-
Examples include tetrakis(2,4-di-tert-butylphenyl) biphenylene diphosphinic acid, cyclic neopentanetetrylbis(2,4-di-tert-butylphenyl)phosphite, and the like.

In the present invention, the copolymer and the solvent can be separated and recovered by any known method of directly heating the polymer solution to remove the solvent; for example, the method of evaporating the solvent with a heating roll (drum dryer method) ) Alternatively, there is a method in which a part of the solvent is evaporated using a flash tower or the like, and then the solvent is further removed using a vented extruder. A particularly preferred method is to concentrate a solution of the block copolymer or its hydrogenated product using a concentrator, and then feed the solution to a twin-screw vented extruder to remove the solvent. More specifically, before supplying the solution to the twin-screw vent extruder, the solution is heated to a polymer concentration of 30 to 95% by weight, preferably 40 to 93% by weight, more preferably 5% by weight.
It is generally concentrated to a concentration of 0 to 90% by weight. If the concentration of the polymer concentrated in the concentrator is less than 300% by weight, the desolvation in the twin-screw vent extruder will be insufficient and it will be difficult to obtain a polymer with little residual solvent, and if the concentration exceeds 95% by weight, it will be difficult to obtain a polymer with little residual solvent. It becomes difficult to transfer the polymer solution from the concentrator to the twin-screw vent pusher. As the concentrator, a fludge tank type concentrator capable of one or two or more stages of concentration, a stirred tank type E4 condenser, a thin film evaporation type concentrator, a wet column type condenser, etc. can be used. The polymer solution fed to the concentrator is generally 12
Preheated to 0-250'C1, preferably 150-220'C. If the preheating temperature is less than 120°C, e
4 Condensation in the condenser was insufficient, and the preheating temperature was 250℃.
Exceeding 'C is not preferable because it causes problems such as gelation of the polymer.

Next, the block copolymer or its solution concentrated as described above is transferred to a twin-screw vent extruder having at least one, preferably 2 to 10, more preferably 3 to 5 vents for degassing. The solvent is degassed under reduced pressure from the vent section. As a vent extruder with such a structure, L/D=10
-60, preferably about 15-50 (L is the length of the screw, D is the outer diameter of the screw), and the screw meshing structure can be either meshing or non-meshing, and the rotation direction may be in the same direction or in different directions.

The screw rotation speed, cylinder heating temperature, and vent pressure of a twin-screw vent extruder are selected taking into account extrusion capacity, polymer properties (viscosity and thermal stability), product quality, etc., and are generally determined by the screw rotation speed. 20-500 revolutions/min, preferably 30-400 revolutions/min, cylinder temperature 100-30
0°C1 preferably 130-260°C, vent pressure 1-500mmHg absolute pressure, preferably 3-400I
nITll1g absolute pressure range.

The amount of residual solvent in the dried polymer directly desolvated and recovered by the method of the present invention is less than 1% by weight, preferably 0.5% by weight.
It is not more than 0.2% by weight, more preferably not more than 0.2% by weight.

When the amount of residual solvent in the dry polymer is 1% by weight or more,
Solvent-free polymers, which are undesirable because they foam during polymer molding and cause appearance defects such as silver, can be obtained in the form of foamed crumbs, granules, or powders. It can also be obtained in the form of strands or pellets.

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 fillers, organic fibers, inorganic fibers, reinforcing agents such as carbon black, other thermoplastic resins, etc. can be used as an additive.

The polymer obtained by the method of the present invention has good thermal stability, is transparent, and has excellent color tone and appearance characteristics.
It can be used as a wide variety of molded products such as sheets, films, injection molded products of various shapes, blow molded products, pressure molded products, vacuum molded products, etc., as well as modification materials for various thermoplastic resins, materials for footwear,
Adhesive and adhesive materials, asphalt modification materials, electric wire and cable materials, vulcanized rubber materials, vulcanized rubber modification materials, materials for houses, automobile parts, industrial parts, household goods, toys, etc. It can be used for 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 (A) to (c)
The weight ratio of polymer to solvent in each of the polymer solutions 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 tetrahydrofuran, and the mixture was heated to 70"
After polymerization at C for 1 hour, a cyclohexane solution containing 20 parts by weight of 1,3-butadiene and 50 parts by weight of styrene was added and polymerized for 2 hours at 70"C. The resulting polymer had a styrene content of 80% by weight. It was a block copolymer with an ABA structure.

[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, 1.3 - A cyclohexane solution containing 25 parts by weight of butadiene was added and polymerized at 70''C for 2 hours.

Thereafter, 5 parts by weight of epoxidized soybean oil was added to obtain a radical structure Pro-Tsuku copolymer with a styrene content of 75% by weight.

[Block copolymer (c)] In a nitrogen gas atmosphere, add n-hexane solution containing 15 parts by weight of 1,3-butadiene and 20 parts by weight of styrene.
- 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 and containing styrene at a total weight 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, 8 parts of isoprene was added.
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 with an A-B-A structure having a styrene content of 20% by weight (polymer concentration of 20% by weight).
weight%).

[Block copolymer (E)] Under 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 the mixture was heated at 70"C. After polymerizing for 1 hour, a cyclohexane solution containing 70 parts by weight of 1,3-butadiene was added to give 70 parts by weight.
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 a block copolymer having an ABA structure with a styrene content of 30% by weight.

Next, the block copolymer obtained above was
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, add n-hexane solution containing 15 parts by weight of 1,3-butadiene and 20 parts by weight of styrene.
- 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.

Examples 1 to 6 and Comparative Examples 1 to 3 To a cyclohexane solution of the block copolymer (A), 1.0 parts by weight of water was added as a reaction terminator per 100 parts by weight of the block copolymer, and the mixture was thoroughly mixed. After the reaction was stopped (first step), the stabilizers shown in Table 1 were added and thoroughly mixed (second step).

The above polymer solution was passed through a heat exchanger and heated to about 200°C, and then introduced into a cylindrical flash tank type concentrator where a portion of the solvent was flash evaporated to give a polymer concentration of about 85% by weight. A concentrated polymer solution was obtained.

Thereafter, the concentrated polymer solution was supplied to a two-screw, two-stage vent extruder, and the solvent was degassed under reduced pressure from the vent section.

The twin-screw vent extruder used had a screenie outer diameter of 40 mm.
L/D is 38.5, screw rotation speed is approximately 300 rpm
I drove. The dried polymer obtained in the form of a strand from the tip of the extruder was cut into a strand shape using a cutter.

The results are shown in Table 1.

(Left below) (Note 1) In AO-1: Above - Shipyard CI], R3 is Lert.
-Amyl group, R2 is an ethynyl group, R2 is a tert-butyl group, R4 is a propyl group phenolic compound AO-2: In the above general 2N), R8 is a tert-
Phenolic compound AO-3 in which R2 is an ethynyl group, R3 is a tert-butyl group, and R4 is a methyl group: In the above-Funazura [I], R+ is a methyl group, R2 is an ethynyl group, and R is a methyl group. is a tert-butyl group, R
Phenolic compound AO-4 in which 4 is hydrogen: in the above-shipped (r), R, is ter
-butyl group, R2 is ethynyl group, R8l is tart-
Phenolic compound AQ-5 in which butyl group and R4 are methyl groups: 2,6-di-tert-butyl-4-methylphenol AQ-5 = octadecyl-3-(3,5-di-tert
-butyl-4-hydroxyphenyl)propionate AO-7: 1,3.5-1-lyntyl-2,4,6-
Tris(3,5-di-tert-butyl-hydroxyhensyl)benzene 80-8: 2,4-bis-(n-octylthio)-6
-(4-Hydroxy-3,5-di-tert-butylanilino) -1,3,5 triazine The amount of each stabilizer added is based on 100 parts by weight of the polymer.

(Note 2) Melt flow value for reworkability at 245°C using a 20aφ single screw extruder (200°C2 load 5k
g).

Mo: Melt flow value without gewaku ○: Retention rate
60% or more and less than 80% △ : Retention rate 40% or more and less than 60% × : Retention rate less than 40% (Note 3) ND-V6B type manufactured by Nippon Denshoku Industries Co., Ltd. Injection molded plate or compression molded plate by comprehensive visual measuring device The b value was measured to adjust the color tone.

The larger the b value, the greater the apparent yellowness.

(Note 4) 5 injection molded plates or compression molded plates with a thickness of 2 mm
The sample was left standing in a hot air dryer at 0°C for two weeks, and the surface bleedability (an indicator of appearance characteristics) was examined.

○・Bleed is not observed.

×Nibrying is observed.

Examples 7 to 12 Block copolymers were obtained in the same manner as Examples 1 to 6 except that the stabilizers shown in Table 2 were added.

The results are shown in Table 2.

(Left below) (Note 5) In AO-91 above - Shipyard III), R1 or ter
t-amyl group, R2 or ethynyl group, R3 is tert-
Phenolic compound AO-10 in which either amyl group or R4 is a methyl group: In the above-shipped CI), R1 or ter
t-octyl group, R2 is ethynyl group, R4l or ter
Examples 13 to 17 of phenolic compounds in which t-octyl group and R4 are propyl groups In a cyclohexane solution of block copolymer CB),
After adding the reaction terminator shown in the table and thoroughly mixing to stop the reaction, add 0.5 parts by weight of phenolic compounds AO-1 and 0.2 parts by weight of AO-5 and mix thoroughly. did.

Solvent removal of the above polymer solution was carried out in the same manner as in Example 1.

The results are shown in Table 3. As shown in Table 3, block copolymers with excellent thermal stability, transparency, and color tone were obtained even when an acid was used as a reaction terminator.

(Note 6) Indicates the molar ratio to the organic lithium compound used in polymerization.

(Note 7) An injection molded plate with a thickness of 2M was molded, and its transparency was measured in accordance with JfS K 6714.

In addition, the vinyl aromatic hydrocarbon content in the polymer is 60%
% or less, a compression molded plate with a thickness of 20 mm was used.

Examples 18-22 AO of reaction terminator and phenolic compound shown in Table 4
Block copolymers were obtained in the same manner as in Examples 13 to 17, except that 0.5 parts by weight of -9 and 0.2 parts by weight of AO-5 were added. The results are shown in Table 4.

(The following is a blank space) Examples 23 to 25 The same stabilizer as in Example 13 was added to the block copolymer solution and reaction terminator shown in Table 5 and mixed thoroughly. The above polymer solution was passed through a heat exchanger and heated to 140°C, and then the solvent was removed using an 8-inch diameter double drum dryer heated to a surface temperature of 180°C to recover the polymer. The recovered polymer was extruded into a strand shape at 200°C using a 30 mmφ twin-screw extruder, and then pelletized using a cutter. The results are shown in Table 5.

(Margin below) (Note 8) Thermal stability of Examples 23, 24, 26, and 27 was determined by the same method as in (Note 2) except that the workpiece temperature was 200'C.

Examples 26 to 28 Block copolymers were obtained in the same manner as in Examples 23 to 25, except that the same stabilizer as in Example 18 was used. The results are shown in Table 6.

(Left below) Example 299 Same as Example 28 using block copolymer (E).
Solvent removal was performed using a reaction terminator and a stabilizer.
2 The solvent removal method was also carried out in the same manner as in Example 28, and the color tone was
No. 1 obtained good pellets. After removing the solvent from the obtained block copolymer, the amount of residual solvent in the polymer was 0.
08% by weight, and Haze 2.9%. or,
Thermal stability was also investigated using the same method as in Example 1, and it was found that there was no increase in melt flow value due to shock decomposition, and the thermal stability was extremely excellent.

〔Effect of the invention〕

The present invention provides a method for recovering a block copolymer or its hydrogenated product by directly removing the solvent from a solution of the polymer or its hydrogenated product, and the resulting polymer contains a specific phenolic compound. The combined use of phenolic stabilizers and phenolic stabilizers provides excellent thermal stability, transparency, color tone, and appearance characteristics. Taking advantage of these characteristics, we can manufacture sheets, films, injection molded products of various shapes, blow molded products, pressure molded products, In addition to being used in a wide variety of molded products such as vacuum-formed products, it can also be used as a modifier for various thermoplastic resins, footwear materials, adhesive/adhesive materials, asphalt modifiers, new materials for electric wires and cables, and processing materials. It can be used for sulfurized rubber materials, vulcanized rubber modification materials, and new materials for home appliances, automobile parts, industrial parts, household goods, toys, etc. In particular, the polymer obtained by method C of the present invention has excellent thermal stability and color tone, so it can be easily processed at room temperature, and is suitable for use in the field of pottery that requires color tone, such as food containers, food packaging materials, and food containers. It can be effectively used for packaging materials, medical supplies, etc.

Patent applicant Asahi Kasei Industries, Ltd.

Claims (1)

[Scope of Claims] 1. Polymerization of a conjugated diene and a vinyl aromatic hydrocarbon using an organolithium compound as an initiator in a hydrocarbon solvent, with a vinyl aromatic hydrocarbon content of 5 to 95% by weight. When obtaining a block copolymer or its hydrogenated product by directly removing the solvent from a solution of a certain block copolymer or its hydrogenated product, (a) In the solution of the block copolymer or its hydrogenated product, , after adding at least one reaction terminator selected from (a) water, (b) alcohol, (c) inorganic acid, and (d) organic acid, (b) to the solution of the block copolymer or its hydrogenated product. (A) 0.05 to 5 parts by weight of the phenolic compound represented by the following general formula [I] per 100 parts by weight of the polymer ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ [I] (In the above formula, R_1 is an alkyl group having 5 or more carbon atoms,
R_2 represents an alkenyl group having 2 to 4 carbon atoms, R_3 represents an alkyl group having 4 to 22 carbon atoms or a cyclohexyl group, and R_4 represents hydrogen or an alkyl group having 1 to 18 carbon atoms. ) (B) A method for producing a block copolymer, which comprises adding 0.01 to 3 parts by weight of a phenolic stabilizer other than the phenolic compound represented by the above general formula [I] to 100 parts by weight of the polymer. .