JPH09143222A - Production of block copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a block copolymer or its hydrogenated product excellent in hue and transparency and having good processing stability. SOLUTION: This production of a block copolymer is, e.g. to add water and carbon dioxide to an active polymer solution of a styrene-butadiene block copolymer in a polymerization vessel, adjust the pH of the solution in the range of 6.5-8.5, add a phenol-based stabilizer having <=5mm Hg vapor pressure at 200 deg.C, introduce a crumb-shaped block copolymer obtained by stripping at a temperature equal to the boiling point or above of the solvent and <=120 deg.C from a feed hopper, use a twin screw vent-type extruder which locates on the down stream of the reed hopper and has 2 slits for dehydrating and one vent part for ventilating, dry the polymer locating in the front position of the feed hopper at 150-250 deg.C, add a phosphorus-based stabilizer in a zone through which the block copolymer substantially containing no water passes on the down stream of the last vent part, introduce the copolymer into a die locating on the down stream of the last vent to obtain a pellet-shaped form.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to desolvation from a solution of a block copolymer comprising a conjugated diene and a vinyl aromatic or a hydrogenated product thereof by a steam stripping method, dehydration and drying with a twin-screw vent extruder. At the same time, the present invention relates to a method for obtaining a block copolymer or a hydrogenated product thereof, which has less gel in the pellets, is excellent in color tone and transparency, has a small amount of residual solvent and water content, and has good processing stability.

[0002]

2. Description of the Related Art A block copolymer composed of a conjugated diene and a vinyl aromatic is transparent and has a similar content to vulcanized natural rubber or synthetic rubber without vulcanization when the vinyl aromatic content is relatively low. Since it has the elasticity at room temperature and has the same processability as that of a thermoplastic resin at a high temperature, it is widely used in the fields of footwear, plastic modification, asphalt, adhesive bonding and the like. A block copolymer having a relatively high vinyl aromatic content is a resin having excellent transparency and impact resistance, and is therefore widely used for sheets, films, injection molded products and the like. 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 them is steam stripping of the block copolymer solution to remove the solvent, followed by dehydration and drying to obtain the block copolymer. It is known how to do it.

For example, JP-A-50-89494 discloses a method of stripping a solvent in the presence of a specific polyether compound, and JP-A-61-218614 discloses a method of removing a solvent by a steam stripping method. After that, a method of removing volatile components with a twin-screw vent extruder is disclosed in JP-A-1-54.
No. 016 discloses a method of adjusting the amount of residual lithium by combining specific treatment steps when removing the solvent by the steam stripping method, and JP-A-1-182308 discloses that the solvent is removed by the steam stripping method. A method for adjusting PH in a particular process step is described.

The block copolymer obtained by combining the above-mentioned conventional techniques with a solvent stripping method by a steam stripping method and drying by a twin-screw vent extruder has high quality, particularly prevention of gel formation, desolvation polymer. It was not always sufficient in terms of balance of molecular chain scission and crosslinking reaction inhibition, color tone, devitrification resistance and the like. Therefore, the block copolymer or its hydrogenated product is processed under high temperature conditions or has a thickness of 0.
When processing into a thin sheet or film having a thickness of 1 mm or less, a problem such as printing failure due to gel mixture occurred. Also, when producing a block copolymer or a hydrogenated product thereof, it is not sufficient to efficiently operate a solvent having a small amount of residual solvent and a low water content, and its solution is desired.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a block copolymer or a hydrogenated product thereof, which has less gel in pellets, is excellent in color tone and transparency, and has good processing stability. To do.

[0006]

That is, according to the present invention, a conjugated diene 90 is prepared by using an organic lithium compound in a hydrocarbon solvent as an initiator.
In producing a block copolymer or a hydrogenated product thereof by steam stripping a solvent from a solution of a block copolymer obtained by polymerizing 5% by weight to 10% to 95% by weight of vinyl aromatic or a hydrogenated product thereof, (1) a step of adding a reaction terminator into a polymerization vessel to an active polymer solution of a block copolymer or a hydrogenated product thereof, (2) a solution of the block copolymer or a hydrogenated product thereof,
A step of adding at least one of (A) carbon dioxide gas and (B) organic acid to adjust the pH of the solution to a range of 6.5 to 8.5, (3) the block copolymer or its hydrogenated product Solution of
One or more phenolic stabilizers having a vapor pressure at 200 ° C. of 5 mmHg or less are used as a block copolymer or its hydrogenated product 100.
A step of adding 0.05 to 3 parts by weight to parts by weight, (4) the solution of the block copolymer or a hydrogenated product thereof,
A step of obtaining a crumb-shaped block copolymer or a hydrogenated product thereof by stripping at a temperature of not less than the boiling point of the solvent or not less than 120 ° C. when the solvent and water are azeotropically distilled, (5) The block copolymer or crumb of the hydrogenated product obtained above is introduced from the feed hopper, and at least two slits for dehydration and downstream of the vent for degassing are provided 2 Using an axial vent extruder,
The vent located in front of the feed hopper is dried at a polymer temperature of 150 to 250 ° C., and a phosphorus-based system is provided in a zone downstream of the final vent where a block copolymer containing substantially no water or its hydrogenated product passes. A method of producing a block copolymer or a hydrogenated product thereof, which comprises the step of adding a stabilizer, introducing the compound into a die positioned downstream thereof, and cutting with a cutter placed immediately after the die to obtain a pellet-like form, Is.

Hereinafter, the present invention will be described in detail. Step of producing solution of block copolymer or hydrogenated product thereof The vinyl aromatic content of the block copolymer of the present invention is 1
It is in the range of 0 to 95% by weight, preferably 15 to 90% by weight. If the vinyl aromatic content of the block copolymer is out of this range, the characteristics of the intended use of the present invention are not exhibited, which is not preferable.

The block copolymer of the present invention has at least 1
A block copolymer having a vinyl aromatic-based polymer block and at least one conjugated diene-based polymer block. Here, the vinyl aromatic polymer-based polymer block means a vinyl aromatic / conjugated diene copolymer block and / or a vinyl aromatic homopolymer block having a vinyl aromatic hydrocarbon content of 50% by weight or more. The conjugated diene-based polymer block means a conjugated diene and a vinyl aromatic copolymer block and / or a conjugated diene homopolymer block containing the conjugated diene in an amount exceeding 50% by weight.

When a random copolymer portion of vinyl aromatic and conjugated diene is present in a polymer block mainly composed of vinyl aromatic or a polymer block mainly composed of conjugated diene, the vinyl aromatic compound is copolymerized. The group may be distributed uniformly in the polymer block or may be distributed in a taper (tapering). Further, in the copolymer portion, a plurality of portions in which vinyl aromatic is uniformly distributed and / or a portion in which taper distribution is formed may coexist.

The block copolymer used in the present invention is, for example, JP-B-36-19286 and JP-B-43-179.
79, Japanese Patent Publication No. 48-2423, Japanese Patent Publication No. 49
-36957 gazette, Japanese Patent Publication No. 57-49567 gazette,
The method described in Japanese Examined Patent Publication No. 58-11446 may be used. Each constituent polymer is a method in which the production conditions are set so as to satisfy the requirements described below, and a conjugated diene and a vinyl aromatic are block-copolymerized using an anion initiator such as an organolithium compound in a hydrocarbon solvent.

The polymer structure of the block copolymer used in the present invention is, for example, A- (BA) _n , A- (BA) _n -B, B- (A-
B) _{n + 1} (wherein A is a polymer block mainly containing vinyl aromatic hydrocarbons, and B is a polymer block mainly containing a conjugated diene. The boundary between the A block and the B block is not always required. It need not be clearly distinguished, n is an integer greater than or equal to 1,
Generally, it is 1-5. ), A linear block copolymer represented by the formula, 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 formula, A and B are the same as the above, 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 is styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinyl. Although there are anthracene, 1,1-diphenylethylene and the like, styrene is particularly common. 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, such as 1,3-butadiene and 2-
Methyl-1,3-butadiene (isoprene), 2,3-
Examples of dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene and the like, and particularly common ones include 1,3-butadiene and isoprene. These may be used alone or in combination of two or more.

As the hydrocarbon solvent, butane, pentane,
Aliphatic hydrocarbons such as hexane, isopentane, heptane and octane, cyclopentane, methylcyclopentane,
Alicyclic hydrocarbons such as cyclohexane, methylcyclohexane, and ethylcyclohexane, and 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 of these include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, hexamethylene dilithium, butadienyl dilithium, isoprenyl dilithium and the like. No. These may be used alone or in combination of two or more.

In the present invention, the polarity is adjusted for the purpose of adjusting the polymerization rate, changing the microstructure (ratio of cis, trans, and vinyl) of the polymerized conjugated diene part, and adjusting the reaction ratio of the conjugated diene and the vinyl aromatic hydrocarbon. 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.

The polymerization temperature for producing the block copolymer in the method of the present invention is generally from -10 ° C to 150 ° C.
It is preferably 40 ° C to 120 ° C. The time required for polymerization depends on the conditions, but it is usually within 48 hours,
Especially preferably, it is 1 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 within a range sufficient to maintain the monomer and solvent in the liquid layer within the above-mentioned polymerization temperature range. Furthermore, 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, generally 5,000 to 1,000,000,
It is preferably 10,000 to 500,000. The amount of hydrocarbons in the block copolymer solution is generally 50 parts by weight to 2000 parts by weight with respect to 100 parts by weight of the block copolymer. 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. During the hydrogenation reaction, the active end of the block copolymer solution may be inactivated by the step of adding a reaction terminator described below, or may be left as it is as the active end.

The hydrogenation rate of the hydrogenation reaction of the present invention can be arbitrarily selected. When the heat deterioration resistance and the like are improved while maintaining the characteristics of the unhydrogenated block copolymer, the fat based on the conjugated diene is used. Hydrogenation of the group double bond to 3% or more and less than 80%, preferably 5% or more and less than 75%, or 80% or more, preferably 90% or more for improving heat deterioration resistance and weather resistance Hydrogenation is recommended. The hydrogenation rate can be measured by a nuclear magnetic resonance apparatus or the like. As the catalyst used in the hydrogenation reaction, (1) a supported heterogeneous catalyst in which a metal such as Ni, Pt, Pd, or Ru is supported on a carrier such as carbon, silica, alumina, or diatomaceous earth; ) Ni, C
So-called Ziegler type catalysts using organic salts such as o, Fe and Cr or acetylacetone salts and reducing agents such as organic Al, or so-called organic complex catalysts such as organic metal compounds such as Ru and Rh, or titanocene compounds as reducing agents. A homogeneous catalyst using organic Li, organic Al, organic Mg or the like is known. Specific methods include the methods described in JP-B-42-8704 and JP-B-43-6636,
Preferably, JP-B-63-4841 and JP-B-63
According to the method described in JP-A-5401, hydrogenation can be carried out in the presence of a hydrogenation catalyst in an inert solvent to obtain a hydrogenated block copolymer solution.

Step (1) Step of adding a reaction terminator To the active polymer solution of the block copolymer or its hydrogenated product,
In this step, a reaction terminator is added to the polymerization vessel. This step is effective in reducing the gel mixed in the finally obtained block copolymer or its hydrogenated product. As a reaction terminator,
Examples thereof include compounds having active hydrogen and organic halides or inorganic halides. As a compound having active hydrogen, water, alcohol, thiol, amine, inorganic acid,
Organic acids and the like are used as organic halides or inorganic halides, alkyl halide compounds, silicon halides,
Examples include tin halide. Suitable quenching agents are water and alcohol. By using a small amount of water and alcohol as a reaction terminator, they are not discharged together with the solvent and do not remain in the polymerization vessel and do not affect the next polymerization system. In particular, water and alcohols having 1 to 3 carbon atoms have a low boiling point, are excellent in volatility, and do not remain in the block copolymer obtained by desolvation or the hydrogenated product thereof, and thus are preferable in that there is no odor.

The addition amount of the reaction terminator in the present invention is preferably 0.6 to 1.5 times equivalent to the organolithium compound. Step (2) Step of adjusting the pH of the solution The initiator used for producing the solution of the block copolymer or the hydrogenated product thereof to which the reaction terminator is added is an organolithium compound, and the polymer solution is a strong base. Is. When a stabilizer such as a phenolic antioxidant is added to the polymer solution in such a state, many stabilizers cause undesired alteration under basic conditions, resulting in deterioration of the color tone of the polymer,
Degradation of thermal stability occurs. In this step, a block copolymer having excellent quality or a hydrogenated product thereof can be obtained by adjusting the pH of the solution using at least one of carbon dioxide gas and an organic acid.

The carbon dioxide gas and the organic acid of the present invention are added in predetermined amounts so that the pH of the solution is in the range of 6.5 to 8.5. When the pH of the solution exceeds 8.5, the color tone is poor, and even when it is less than 6.5, the color tone is not improved, and since carbon dioxide gas and organic acid are present as they are in the block copolymer or its hydrogenated solution, There is a possibility of facility corrosion and the like, which is not preferable. Here, the PH of the solution means that a part of the solution is sampled and distilled water (PH 7.0 ± 0.5) having the same weight as the solution is taken.
(1) is thoroughly mixed with the solution, and then allowed to stand to display the PH of the aqueous layer separated into two layers. PH can be measured using a glass electrode type hydrogen ion concentration meter (PH meter).

The organic acid used in the present invention is, in a broad sense, an organic compound having acidity, and examples thereof include compounds such as carboxylic acid, sulfonic acid, sulfinic acid, and phenol, but an organic compound containing a carboxyl group is preferable. hand,
Preferred are (1) fatty acids having 8 or more carbon atoms and (2) aromatic carboxylic acids. Specific examples of fatty acids preferably used in the present invention include octyl acid, capric acid, lauric acid,
Examples thereof include myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, behenic acid, and mixtures thereof. Examples of aromatic carboxylic acids include benzoic acid, chlorobenzoic acid, aminobenzoic acid, cinnamic acid, phenylacetic acid, and mixtures thereof. The carbon dioxide gas to be used may be in a gaseous state or a solid state, and may be added in a state of being dissolved in water or a solvent.

Step (3) Step of Adding Phenolic Stabilizer In the present invention, the above carbon dioxide gas or organic acid or a mixture thereof is added and mixed, and then the phenol stabilizer of the present invention is added. It is necessary to prevent alteration due to oxidative deterioration of the block copolymer or its hydrogenated product. Use of the phenolic stabilizer having a vapor pressure of 5 mmHg or less at 200 ° C. of the present invention prevents volatilization of the phenolic stabilizer during desolvation, dehydration and drying in the next step, and exerts an effect corresponding to the addition amount. . On the contrary, when a phenolic stabilizer having a vapor pressure at 200 ° C. of more than 5 mmHg is used, the thermal stability of the phenolic stabilizer is significantly reduced because of large volatilization of the phenolic stabilizer, which is not preferable.

The phenolic stabilizer of the present invention has a temperature of 200 ° C.
A phenolic stabilizer having a vapor pressure of 5 mmHg or less can be used, and these may be added to the solution as they are, or may be added after being dissolved in a hydrocarbon solvent. As a preferable phenolic stabilizer, 2- [1- (2-hydroxy-3,5
-Di-t-pentylphenyl) ethyl] -4,6-di-
t-pentylphenyl acrylate, 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-tert-butyl-4-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-
Hydroxybenzyl) benzene, 2,4-bis- (n-
Octylthio) -6- (4-hydroxy-3,5-di-
t-Butylanilino) -1,3,5-triazine and the like. The above phenolic stabilizers may be used in combination of two or more. These phenolic stabilizers are used in an amount of 0.05 to 3 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the block copolymer or hydrogenated product thereof. When the amount of the phenol-based stabilizer used is less than 0.05 parts by weight, the effect of improving stability is not observed, and conversely, when it exceeds 3 parts by weight, the effect outside the range of the present invention is not exhibited.

Step (4) Step of obtaining crumb-shaped block copolymer In order to remove the solvent from the solution to which the phenolic stabilizer is added, the solvent is removed by a steam stripping method, and the crumb-shaped block copolymer or This is the step of obtaining the hydrogenated product. A preferred embodiment of removing the solvent by steam stripping of the present invention is generally to use a surfactant as a crumbing agent during steam stripping, and one example of such a surfactant is an anionic surfactant. It is an active agent, a cationic surfactant, or a nonionic surfactant. These surfactants are generally added in an amount of 0.1 to 3000 ppm with respect to the water in the stripping zone. In addition to these surfactants, Li, Na, Mg,
A water-soluble salt of a metal such as Ca, Al or Zn can be used as a crumb dispersion aid. The concentration of the crumb-like polymer dispersed in water is generally 0.1 to 20% by weight (the ratio of the stripping zone to water), and if it is in this range, good particles can be obtained without causing any trouble in operation. A crumb having a diameter can be obtained.

The temperature range in the steam stripping method of the present invention is not less than the boiling point of the solvent or not less than azeotropic temperature and not more than 120 ° C. when the solvent and water are azeotropic, preferably the boiling point or azeotropic temperature of the solvent. More than 10 ℃ higher than 110
The temperature is not higher than 0 ° C, more preferably not lower than 15 ° C and not higher than 100 ° C. When the boiling point is lower than the boiling point of the solvent or lower than the azeotropic temperature of the solvent and water, the removal of the solvent is poor and the amount of the residual solvent in the crumb increases. On the other hand, if the temperature during steam stripping exceeds 120 ° C., it is not preferable because a crumb having a small grain size cannot be obtained.

Step (5) Dehydration, Drying and Addition of Phosphorus Stabilizer This step is a step of dehydrating and drying the block copolymer or its hydrogenated crumb and adding a phosphorus stabilizer. is there. In the present invention, a block copolymer or its hydrogenated crumb is introduced from a feed hopper, and at least two slits for dehydration and downstream thereof, at least two slits for dehydration and at least one vent for degassing, are twin-screw vent extrusion. Using a machine,
dry. Since one dehydration slit cannot sufficiently dehydrate, the residual solvent amount and the water content are increased, which is not preferable. At least one vent for degassing is required, and the vent zone preferably has a range of L / D = 3.5 to 10.5 from the viewpoint of degassing ability. The preferred residual solvent amount of the present invention is 2000 pp
m or less, more preferably 1000 ppm or less, preferable water content is 1000 ppm or less, more preferably 5
It is not more than 00 ppm.

The temperature of the block copolymer or its hydrogenated product passing through the slit of the twin-screw vent extruder, which is the dehydration of the present invention, is 50 when passing through the slit of the first stage located downstream from the feed hopper. ~ 120 ° C, and the barrel temperature immediately after passing the first-stage slit is 180-250 ° C.
It is preferable to set the temperature to 70 ° C. to 150 ° C. and the temperature passing through the slit located further downstream. If the temperature of the block copolymer of the first stage slit or its hydrogenated product is outside the range of 50 to 120 ° C., water cannot be sufficiently squeezed, which is not preferable. Further, the barrel temperature immediately after passing the first-stage slit is set to 180 to 250 ° C., and the temperature of the block copolymer of the slit located further downstream or its hydrogenated product is 7
If the temperature is out of the range of 0 to 150 ° C., the vent located downstream cannot be sufficiently dried, which is not preferable. The temperature of the block copolymer or its hydrogenated product when passing through the vent is 15
It is 0 to 250 ° C., preferably 180 to 230 ° C. If the temperature of the block copolymer or its hydrogenated product at the time of passing through the vent portion is less than 150 ° C., the drying is not sufficient and
If the temperature exceeds ℃, the molecular chain of the polymer is significantly broken and cross-linked, which is not preferable.

In the block copolymer of the present invention or its hydrogenated product, a reaction terminator is added in the polymerization vessel in the step before the desolvation step, and a specific phenolic stabilizer is added after adjusting the pH of the solution. Therefore, even if the polymer temperature is 200 ° C. or higher, the breaking and cross-linking of the polymer molecular chains are small, the efficiency of solvent removal is good, and it is effective in improving productivity. The Applicant has added a phosphorus-based stabilizer to the extruder zone through which the substantially water-free block copolymer or hydrogenated product thereof passes downstream of the final vent portion in this step,
It has been found that the thermal stability is increased without compromising the quality of the block copolymer or its hydrogenated product. The term "substantially free of water" means that the water content of the block copolymer or its hydrogenated product is 1000 ppm or less, preferably 500 pp.
It means that it is less than or equal to m. Although the addition of a phosphorus-based stabilizer exerts a thermal stability effect, some such as tris (nonylphenyl) phosphite are easily hydrolyzed when contacted with water for a long time or when kneading at high temperature in the presence of water. However, unlike the steam stripping method, the solvent removal step cannot be performed in the presence of water in the polymer solution. In particular, hydrolysis of tris (nonylphenyl) phosphite is not preferable because it not only contributes to improving the thermal stability of the polymer but also deteriorates transparency and devitrification resistance. According to the method of the present invention, the added phosphorus-based stabilizer is not decomposed and a corresponding effect can be obtained. The screw structure of the zone to which the phosphorus stabilizer is added is not particularly limited, but it is preferable to have a kneading disk. The kneading disk may be a right-hand screw direction type, a left-hand screw direction type, or an orthogonal type. By this, the dispersion of the phosphorus-based stabilizer in the polymer becomes good, but the effect is remarkably exhibited especially under the condition that the added amount is large. The method of adding the phosphorus-based stabilizer is not particularly limited, but in a state of being melted or dissolved or dispersed in an oily liquid substance,
A method of adding with a metering pump or the like is preferable. The phosphorus-based stabilizer of the present invention includes tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, tris (2-t-butyl-4-methylphenyl) phosphite, and bis. (2,4 di-t-butylphenyl) pentaerythritol diphosphite, tetrakis (2,4 di-t-butylphenyl) -4,4-bisphenylene diphosphite, bis (2,6 di-t-butyl) Examples include -4-methylphenyl) pentaerythritol diphosphite, and the use of tris (nonylphenyl) phosphite is preferable from the viewpoint of maximizing the effects of the present invention. The preferred addition amount of the phosphorus-based stabilizer is 0.05 to 3 parts by weight with respect to 100 parts by weight of the block copolymer.

The twin-screw vent extruder used in the present invention is not particularly limited to a structure having a gear pump between the screw tip and the discharge die, but a twin-screw vent extruder equipped with a gear pump. Even if the screw rotation speed is increased by using, it is possible to smoothly discharge, so that the pressure increase of the block copolymer or its hydrogenated product is suppressed and the rise of the polymer temperature is prevented, and the thermal stability is improved. Contribute to. The die is for underwater cutting or hot cutting, and the cutter has 2 to 6 blades according to the required pellet size.

The twin-screw vent extruder used in the present invention is L / D.
= 30 to 60 (L is the length of the screw, D is the outer diameter of the screw), and a meshing type co-directional twin-screw vent extruder is preferable. FIG. 1 shows an example of the steps of dehydration, drying and adding a phosphorus-based stabilizer using a meshing type co-directional twin-screw vent extruder. The crumb-like polymer obtained by desolvating by the steam stripping method is introduced into the feed hopper (2) of the extruder (1) equipped with the twin screw (9). The extruder is equipped with two slits (3), which remove most of the water in the crumbs. The polymer is transported forward by a twin screw. Two vents (4) are placed in the extruder (1) to dry and remove the remaining water and solvent, and the vents dry to a substantially water-free state in front of them. Is provided with an introducing means (5) for introducing tris (nonylphenyl) phosphite, passes through a die (7) through a gear pump (6), and is cut into a pellet form by a cutter (8). It FIG. 2 shows an enlarged example of the phosphorus stabilizer addition zone. A means (5) for introducing tris (nonylphenyl) phosphite is provided between the final vent section (4) and the gear pump (6), and the screw structure thereof is a left-handed kneading disk (10).

[0033]

The preparation of the active polymer solution of the block copolymer used in the examples is shown below. The weight ratio of the active polymer solution polymer to the solvent 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 the partial polymerization, cyclohexane containing 70 parts by weight of butadiene was added and the polymerization was carried out at 70 ° C. for 60 minutes. Then, a cyclohexane solution containing 15 parts by weight of styrene was further added, and polymerization was carried out at 70 ° C. for 20 minutes. A block copolymer having an ABA structure with a styrene content of 30% by weight was obtained. [Block Copolymer (B)] Under a nitrogen gas atmosphere, n-butyllithium was added to a cyclohexane solution containing 15 parts by weight of 1,3 butadiene and 20 parts by weight of styrene in an amount of 0.
After 11 parts by weight was added and the mixture was polymerized at 70 ° C. for 40 minutes, cyclohexane containing 45 parts by weight of 1,3-butadiene and 20 parts by weight of styrene was further added, and polymerization was performed at 70 ° C. for 60 minutes.
A block copolymer having a BABA structure having a styrene content of 40% by weight was obtained. [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 0 minutes of polymerization, cyclohexane containing 40 parts by weight of butadiene was added and polymerization was carried out at 70 ° C. for 40 minutes. Then, a cyclohexane solution containing 30 parts by weight of styrene was further added, and polymerization was carried out at 70 ° C. for 30 minutes. Styrene content 60% by weight
A block copolymer having an A-B-A structure was obtained. [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 the mixture was heated at 70 ° C. for 15 minutes. After being polymerized for a minute, a cyclohexane solution containing 82 parts by weight of 1,3-butadiene was added and polymerized at 70 ° C. for 40 minutes. Then, cyclohexane containing 9 parts by weight of styrene was added and polymerization was carried out at 70 ° C. for 15 minutes. A block copolymer having an ABA structure with a styrene content of 18% by weight was obtained. Next, this block copolymer was prepared as described in JP-A-59-133203.
Hydrogenation was carried out using the Ti-based hydrogenation catalyst described in Japanese Patent Publication No. 1993-242242 to obtain a hydrogenated block copolymer having a butadiene portion hydrogenation rate of 95%. [Block Copolymer (E)] n was added to a cyclohexane solution containing 20 parts by weight of styrene under a nitrogen gas atmosphere.
-Add 0.08 parts by weight of butyllithium and add 3 at 75 ° C.
After polymerization for 0 minutes, cyclohexane containing 30 parts by weight of 1,3-butadiene and 25 parts by weight of styrene was continuously added, and the mixture was polymerized at 75 ° C. for 100 minutes. Then styrene 2
A cyclohexane solution containing 5 parts by weight was added, and polymerization was carried out at 75 ° C. for 30 minutes. AB with styrene content of 70% by weight
A block copolymer having a -A structure was obtained. [Block Copolymer (F)] In a nitrogen gas atmosphere, 0.08 parts by weight of n-butyllithium was added to a cyclohexane solution containing 25 parts by weight of styrene and 0.3 parts by weight of tetrahydrofuran, and polymerization was performed at 70 ° C. for 20 minutes. After doing
Further, cyclohexane containing 20 parts by weight of 1,3-butadiene and 55 parts by weight of styrene was added and polymerization was carried out at 70 ° C. for 30 minutes. A block copolymer with an ABA structure having a styrene content of 80% by weight was obtained. [Block Copolymer (G)] Under a nitrogen gas atmosphere, n was added to a cyclohexane solution containing 75 parts by weight of styrene.
-Add 0.15 parts by weight of butyllithium, continuously add at 75 ° C and polymerize for 60 minutes, then add cyclohexane containing 25 parts by weight of 1,3-butadiene continuously and add at 75 ° C for 40 minutes. Polymerized. After that, 1,3 screws (N,
N-glycidylaminomethyl) cyclohexane was added in a molar ratio of 0.25 to n-butyllithium to obtain a radial block copolymer having a styrene content of 75% by weight.

[0034]

Example 1 After the block copolymer (E) was polymerized, water was added
The reaction was stopped by adding 0.9 times equivalent to butyllithium in the polymerization vessel. Then, the polymerization solution was transferred from the polymerization vessel to another reaction tank, and carbon dioxide gas was added to adjust the pH of the solution to 7.6. In this solution, 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate (hereinafter stabilizer) was added to 100 parts by weight of the polymer. 0.5)
Parts by weight, 0.2 parts by weight of n-octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (hereinafter referred to as stabilizer B) was added and uniformly mixed.
In steam stripping the above block copolymer, α- (p-nonylphenyl) -ω-hydroxypoly (oxyethylene) dihydrodiene phosphate ester and monohydrodiene phosphate ester are used as a crumbing agent. The mixture (poly (oxyethylene) oxyethylene unit having an average value of 9 to 10) was used at 30 ppm with respect to water in the stripping zone, and the solvent was removed at a temperature of 90 to 98 ° C. The concentration of crumb in the slurry in the solvent removal tank was about 5% by weight, and the water content of crumb was 52% by weight. Next, the crumb obtained above was supplied to a twin-screw vent extruder from a hopper for dehydration and drying. The extruder used was a mesh type same-direction biaxial two-stage vent extruder with screw outer diameter of 65 mm and L / D = 40. It has two slits between the hopper and the vent part, and the screw tip and A gear pump is attached between the dies. The operating conditions were a screw rotation speed of 155 rpm, a polymer extrusion rate of 135 kg / hour, and the pressure (absolute pressure) of the vent part was reduced to 300 mmHg for the first stage and 200 mmHg for the second stage. Tris (nonylphenyl) phosphite (hereinafter referred to as TNP) is used at a temperature of 50 ° C. and a plunger type metering pump is used to control the pressure difference between the second vent and the gear pump.
5 parts by weight was added. The barrel temperature and polymer temperature of the first slit part of the extruder are 50 ° C or lower, 63 ° C, and 2nd, respectively.
Barrel temperature of slit and polymer temperature are 50
The temperature was 138 ° C. or lower, and the barrel temperature in the middle of the first and second slits was 230 ° C.

The residual cyclohexane content of the polymer obtained in Example 1 was 720 ppm, the water content was 360 ppm,
The polymer temperature at the first vent was 189 ° C, the polymer temperature at the second vent was 197 ° C, and the polymer temperature at the die outlet was 212 ° C. Further, the residual ratios of the added phenolic stabilizer and TNP were both 95% by weight or more, and volatilization of the phenolic stabilizer and hydrolysis of TNP were not observed. Table 1 shows the results such as the quality of the obtained polymer.

In the table, the addition amount is parts by weight and the residual cyclohexane is ppmw.

[0037]

[Table 1]

(Note 1) ND-V manufactured by Nippon Denshoku Industries Co., Ltd.
The b value of the pellets was measured using a Model 6B total vision measuring machine. The larger the b value, the greater the apparent yellowness. (Note 2) Pellets are compression molded (200 ° C) to a thickness of 2 m.
m sheets were prepared. The haze (%) of this sheet is AS
It measured based on TMD-1003. (Note 3) A 2 mm-thick sheet was used as a test piece and immersed in warm water at 60 ° C for 150 minutes, and then the haze (%) of each test piece
Was measured according to ASTM D-1003, and the difference from the haze value (%) before immersion was determined. The larger the difference, the worse the devitrification resistance. (Note 4) 50 g of pellets are dissolved in 200 ml of toluene and suction-filtered with a filter paper having a diameter of 70 mm (thickness: 0.2 mm, retained particle size: 6 μm, collection efficiency: 65%), and then the dye (violet 36) remains. After dyeing the difference and leaving for 5 minutes,
The gel amount of the filter paper was visually determined based on the following criteria.

⊚: The number of large pieces is 0, or the inside is 3 or less,
Or, the number of small is 5 or less. O: The number of large is 0, or the number of medium is 4 to 10, or the number of small is 6.
〜20 pieces △: 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 has a diameter of less than 0.2 mm, medium has a diameter of 0.2-0.
(5 mm, large diameter is larger than 0.5 mm) (Note 5) The pellet was heated to a temperature of 230 ° C. in a nitrogen atmosphere and left standing for 60 minutes. The molecular weight distribution of this pellet was measured by gel permeation chromatography (GPC) and overlapped with the molecular weight distribution of the pellet before standing in the same area, and the low molecular weight side (molecular weight chain breaking part) and the high molecular side (crosslinking part) The difference is expressed in% by weight. (Note 6) 50 g of pellets were placed in a 100 ml glass container tightly stoppered, left standing for 60 minutes at a temperature of 70 ° C., immediately taken out, and an odor sensory test was conducted according to the following criteria.

⊚: No odor, ◯: Slight odor but not unpleasant, ×: Clear odor

[0041]

Examples 2 and 3 After the block copolymers (F) and (G) were polymerized, ethanol was added to n-butyllithium (F).
Was added to the polymerization vessel in an amount of 0.8 times equivalent to (G) and 0.7 times equivalent to (G) to n-butyllithium to stop the reaction. Table 2 shows the subsequent process conditions.
The process conditions, extruder specifications, etc. of the parts not shown in Table 2 were the same as in Example 1. The water content of all the obtained polymers was 350 ppm or less, the residual ratios of the phenolic stabilizer and TNP were both 95% by weight or more, and volatilization of the phenolic stabilizer and hydrolysis of TNP were not observed. Table 1 shows the results such as the quality of the obtained polymer.

[0042]

[Table 2]

[0043]

Examples 4 to 7 Block copolymers (A), (B),
After polymerizing and hydrogenating (C) and (D), ethanol was added in an amount of 0.9 times equivalent to (A) with respect to n-butyllithium, and water was added to n-.
0.8 times equivalent of (B) to butyl lithium, 0.7 times equivalent of (C) to methanol and 1.3 times equivalent of (D) to n-butyllithium were added to the polymerization vessel. To stop the reaction. Stripping is a mixture of a dihydrodiene phosphate ester of α- (p-nonylphenyl) -ω-hydroxypoly (oxyethylene) and a monohydrogen phosphate ester as a crumbing agent (poly (oxyethylene) oxy ester). As the ethylene unit, an average value of 9 to 10) was used at 3 ppm with respect to water in the stripping zone, and the solvent was removed at a temperature of 90 to 98 ° C. The concentration of crumb in the slurry in the solvent removal tank was about 5% by weight, and the water content of crumb was in the range of 45 to 53% by weight. The screw rotation speed of the extruder was in the range of 130 to 250 rpm, and other process conditions are shown in Table 2. The process conditions, extruder specifications, etc. of the parts not shown in Table 2 were the same as in Example 1. The water content of all the obtained polymers is 450.
It was below ppm, the residual ratio of the phenolic stabilizer and TNP was 95% by weight or more, and volatilization of the phenolic stabilizer and hydrolysis of TNP were not observed. Table 5 shows the results such as the quality of the obtained polymer. The measurement method in Table 1 is the same as that in Example 1 except that the weight of the gel pellet is 5 g.

[0044]

Example 8 As a result of measuring the polymer quality and the like at the time when 20 batch polymerization was repeated in the same manner as in Example 4, the gel amount was as good as ◯.

[0045]

[Comparative Examples 1 to 4] After the block copolymer (E) was polymerized, water was added to the polymerization vessel at 0.8 times equivalent to that of n-butyllithium to terminate the reaction. The process conditions thereafter are shown in Table 6. Comparative Example 2 has a phenolic stabilizer of 200
2,6-di-t- whose vapor pressure at ℃ is about 120 mmHg
Butyl-4-methylphenol (hereinafter referred to as stabilizer C)
Comparative Example 4 was stripped after adding TNP. 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. The residual ratio of the stabilizer C of Comparative Example 2 was 10% by weight or less, and the residual ratio of TNP of Comparative Example 4 was 5% by weight or less. The residual ratios of the phenolic stabilizer and TNP in Comparative Examples 1 and 3 were all 95% by weight or more, and neither volatilization of the phenolic stabilizer nor hydrolysis of TNP 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 block copolymer (B) was polymerized, water as a reaction terminator was not added to the polymerization vessel, but the polymerization solution was transferred from the polymerization vessel to another reaction tank and added, and then carbon dioxide gas was added. A polymer was obtained in the same manner as in Example 1 except that the pH of the solution was adjusted by adding. When the quality of the polymer and the like at the time when this method was repeated 20 batches were measured by the same method as in Example 4, the gel amount was x and a large number of gels considered to be produced in the polymerization vessel were observed.

[0049]

Comparative Example 6 The polymer temperature of the extruder in Example 2 was 142 ° C. in the first vent section and 178 in the second vent section.
A polymer was obtained in the same manner as in Example 2 except that the temperature was 0 ° C and the temperature at the die outlet was 193 ° C. Residual cyclohexane of the obtained pellets is 3500ppm, water content is 7900ppm
Therefore, the transparency was extremely poor at 91%, and bubbles were observed in the injection-molded product.

[0050]

EFFECT OF THE INVENTION The block copolymer or hydrogenated product thereof according to the production method of the present invention has less gel in pellets, is excellent in color tone and transparency, and has good processing stability. The block copolymer or hydrogenated product thereof obtained by the present invention makes use of its characteristics, and can be used for various molded products such as sheets, films, injection molded products of various shapes, vacuum molded products, pressure molded products, and hollow molded products. Widely used in footwear, plastic modification, asphalt, adhesive field, etc. In particular, the block copolymer or its hydrogenated product obtained by the method of the present invention has little gel and is excellent in heat deterioration resistance, so that it is used in the field of thin sheets or films, etc., and adhesives for spiral spray coating, styrene. It can be suitably used as a modifier for thin sheets or films of resin.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a process of the present invention.

FIG. 2 is a schematic view of a phosphorus-based stabilizer addition zone process of the present invention.

[Explanation of symbols]

 1; Extruder 2; Supply hopper 3; Slit 4; Vent part 5; Phosphorus stabilizer introduction part 6; Gear pump 7; Die 8: Cutter 9; Twin screw 10; Kneading disk

Claims (2)

[Claims] 1. A solvent from a solution of a block copolymer obtained by polymerizing 90 to 5 wt% of a conjugated diene and 10 to 95 wt% of a vinyl aromatic in a hydrocarbon solvent as an initiator, or a hydrogenated product thereof. In producing a block copolymer or a hydrogenated product thereof by steam stripping, (1) a step of adding a reaction terminator to a polymerization reactor in an active polymer solution of the block copolymer or its hydrogenated product (2) In the solution of the block copolymer or hydrogenated product thereof,
A step of adding at least one of (A) carbon dioxide gas and (B) organic acid to adjust the pH of the solution to a range of 6.5 to 8.5, (3) the block copolymer or its hydrogenated product Solution of
One or more phenolic stabilizers having a vapor pressure at 200 ° C. of 5 mmHg or less are used as a block copolymer or its hydrogenated product 100.
A step of adding 0.05 to 3 parts by weight to parts by weight, (4) the solution of the block copolymer or a hydrogenated product thereof,
A step of obtaining a crumb-shaped block copolymer or a hydrogenated product thereof by stripping at a temperature of not less than the boiling point of the solvent or not less than 120 ° C. when the solvent and water are azeotropically distilled, (5) The block copolymer or crumb of the hydrogenated product obtained above is introduced from the feed hopper, and at least two slits for dehydration and downstream of the vent for degassing are provided 2 Using an axial vent extruder,
The vent located in front of the feed hopper is dried at a polymer temperature of 150 to 250 ° C., and a phosphorus-based system is provided in a zone downstream of the final vent where a block copolymer containing substantially no water or its hydrogenated product passes. A method of producing a block copolymer or a hydrogenated product thereof, which comprises the step of adding a stabilizer, introducing the compound into a die positioned downstream thereof, and cutting with a cutter placed immediately after the die to obtain a pellet-like form, . 2. The temperature of the block copolymer or its hydrogenated product in the first-stage slit located downstream from the feed hopper in step (5) is 50 to 120 ° C., and the first-stage slit is used. The block copolymer according to claim 1, wherein the barrel temperature immediately after passage is set to 180 to 250 ° C, and the temperature of the block copolymer of the slit located further downstream or its hydrogenated product is 70 to 150 ° C. Method for producing hydrogenated product.