JPH08104709A - Epoxidized block copolymer - Google Patents

Abstract

PURPOSE: To obtain an epoxidized block copolymer reduced in the amount of a gel. CONSTITUTION: This copolymer is prepared by epoxidizing a block copolymer composed of a block of a polymer based on a vinylaromatic hydrocarbon compound and a block of a polymer based on a conjugated diene compound or a product of hydrogenation thereof and has an acid value of 10mgKOH/g or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxidized block copolymer suitable as a modifier or modifier aid for rubber-like polymers or resinous polymers, adhesives, sealants and the like.

[0002]

2. Description of the Related Art A block copolymer comprising a vinyl aromatic hydrocarbon compound and a conjugated diene compound and its hydrogenated product are transparent and have the same properties as vulcanized natural rubber or synthetic rubber without vulcanization. Since it has elasticity at room temperature and has the same processability as a thermoplastic resin at high temperature, it is widely used in the fields of various modifiers and adhesives. For the purpose of further improving the above performance, a method of using an epoxidized block copolymer obtained by epoxidizing an unsaturated carbon bond derived from a diene block of a block copolymer or a hydrogenated product thereof, The present inventors have many ideas. For example, as a composition using the epoxidized block copolymer or its application, Japanese Patent Application No. 6-5639 discloses a composition with a thermoplastic resin, and Japanese Patent Application No. 6-772 discloses a compatibilizer for resin and a resin. A composition, and Japanese Patent Application No. 6-67187 proposes an adhesive composition.

On the other hand, JP-A-5-125197 contains an epoxy-functionalized polydiene block polymer (radiation).
A crosslinkable adhesive composition is described, and the obtained polymer can be melt-processed before crosslinking, has a high gel content after crosslinking, and has improved heat resistance and solvent resistance. Has been described.

[0004]

However, in the epoxidized block copolymers described in the above prior art, when the epoxidation reaction is carried out in the presence of an acid catalyst, the epoxy ring is partially opened, It is stated that it can contain both epoxide and hydroxyester groups. In addition, even if an epoxidized block copolymer having a low gelled substance content is obtained before crosslinking, a gelled substance may be formed when the epoxidized block copolymer is heat-melted and molded thereafter.
The formation of such a gelled substance has a problem that molding processability is significantly adversely affected.

[0005]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the inventors of the present invention have found that the acid value of the epoxidized block copolymer has a great influence on the amount of gelation product. Therefore, the present invention has been completed.

That is, the present invention relates to a block copolymer comprising a polymer block (A) mainly containing a vinyl aromatic hydrocarbon compound and a polymer block (B) mainly containing a conjugated diene compound, or a block copolymer thereof. The acid value of the epoxidized block copolymer obtained by epoxidizing the hydrogenated product is 10
It is an epoxidized block copolymer characterized by having a content of mgKOH / g or less ”.

The block copolymer referred to in the present invention is a block copolymer composed of a polymer block (A) mainly containing a vinyl aromatic hydrocarbon compound and a polymer block (B) mainly containing a conjugated diene compound. A polymer. Further, the hydrogenated product of the block copolymer refers to a polymer obtained by partially hydrogenating the unsaturated carbon bond existing in the polymer block (B) of the block copolymer by a hydrogenation reaction. The epoxidized block copolymer referred to in the present invention refers to a polymer obtained by epoxidizing the unsaturated carbon bond present in the polymer block (B) of the block copolymer or its hydrogenated product.

As typical examples of vinyl aromatic hydrocarbon compounds which can form a block copolymer, various alkyl-substituted styrenes such as styrene and α-methylstyrene, alkoxy-substituted styrene, vinylnaphthalene, alkyl-substituted vinylnaphthalene, divinylbenzene, Examples include vinyltoluene and the like. Of these, styrene is preferred. It is also possible to use one of these or a combination of two or more. Typical examples of the conjugated diene compound that can form the block copolymer include 1,3-butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3.
-Butadiene, piperylene, 3-butyl-1,3-octadiene, phenyl-1,3-butadiene and the like.
Among these, 1,3-butadiene and isoprene are preferable because they are inexpensive and easily available. It is also possible to use one of these or a combination of two or more.

The copolymerization composition ratio of the vinyl aromatic hydrocarbon compound and the conjugated diene compound which can form the block copolymer is preferably 5/95 to 70/30, and more preferably 1
It is 0/90 to 60/40. The number average molecular weight of the block copolymer usable in the present invention is preferably 5,000 to 60,000, more preferably 10,000 to 50,000. When the molecular weight is low, the properties of the rubber-like elastic body are difficult to be exhibited, and when the molecular weight is high, it is difficult to melt, which is not preferable. The structure of the block copolymer is not particularly limited, for example,
It may be a block copolymer of a vinyl aromatic hydrocarbon compound represented by A-B-A, B-A-B-A, A-B-A-B-A, etc. and a conjugated diene compound. The structure of the molecule itself may be any of linear, branched, radial, etc., and may be any combination thereof. The method for producing the block copolymer before epoxidation is not particularly limited, and any method may be used.

For example, Japanese Patent Publication No. 40-23798 and Japanese Patent Publication No. 47-3252
As described in JP-B-48-2423 and JP-B-56-28925, there may be mentioned a method of producing in an inert solvent using a lithium catalyst or the like. The method for producing the hydrogenated product of the block copolymer is not particularly limited, and any method may be used.

For example, Japanese Patent Publications 42-8704 and 43-6636
And the like, there may be mentioned a method for producing a block copolymer by hydrogenating it in the presence of a hydrogenation catalyst in an inert solvent. The amount of hydrogenation is not particularly limited, but it is necessary that an unsaturated carbon bond capable of reacting with the epoxidizing agent remains in the molecule during the subsequent epoxidation reaction. The block copolymer or its hydrogenated product is dissolved or slurried in an appropriate organic solvent and then epoxidized. The site epoxidized by the epoxidizing agent is an unsaturated bond existing in the polymer block (B).

Typical examples of the organic solvent which can be used in the epoxidation include linear and branched hydrocarbons such as pentane, hexane, heptane and octane and their alkyl-substituted derivatives, cyclopentane, cyclohexane and cycloheptane. Such as alicyclic hydrocarbons and their alkyl-substituted derivatives, aromatic and alkyl-substituted aromatic hydrocarbons such as benzene, naphthalene, toluene and xylene, and aliphatic carboxylic acid esters such as methyl acetate, ethyl acetate and propyl acetate. Can be mentioned. Of these, cyclohexane, ethyl acetate, chloroform, toluene, xylene, and hexane are preferable from the viewpoint of solubility of the block copolymer or its hydrogenated product and the ease of subsequent solvent recovery. Further, as typical examples of the epoxidizing agent that can be used in the epoxidation reaction, peracetic acid, perbenzoic acid, formic acid, organic peracids such as trifluoroperacetic acid, hydrogen peroxide, hydrogen peroxide and low molecular weight compounds. And the like.

In the epoxidation, a catalyst can be used if necessary. Of these, peracetic acid, which is industrially produced in large quantities and can be obtained at a low cost and has a relatively high stability, is preferable as the epoxidizing agent. The amount of the epoxidizing agent used is not particularly limited, and the reactivity of the epoxidizing agent used, the desired degree of epoxidation, the unsaturated carbon bond in the block copolymer used or its hydrogenated product. Depending on the conditions such as the amount, any appropriate amount can be used. The epoxidation reaction temperature varies depending on the type and amount of the epoxidizing agent used, the solvent used, the block copolymer or its hydrogenated product, and is not particularly limited.

For example, when using peracetic acid as an epoxidizing agent, the reaction temperature is preferably 0 to 70 ° C. 0
If the temperature is lower than 70 ° C, the reaction rate is slow, and if the temperature exceeds 70 ° C, the formed epoxy group is opened and the decomposition of peracetic acid proceeds, which is not preferable. In order to improve the stability of peracetic acid, phosphates may be added to the reaction system during the epoxidation reaction. Then, the solvent is removed and the epoxidized block copolymer is recovered after drying.

Examples of the method for removing the solvent include a method of steam stripping in the presence of a surfactant and a method of directly removing the solvent under heating. The steam stripping method, cationic, anionic, amphoteric, in the presence of a nonionic surfactant, the boiling point of the organic solvent or the azeotropic temperature or more when the solvent and water are azeotropic, 120, This is a method in which a solvent is stripped at a temperature of ℃ or less to obtain a slurry in which a crumb-like polymer is dispersed in water. The direct solvent removal method is a method of removing the solvent by using a vacuum dryer or the like.

Then, dehydration and drying are performed to obtain an epoxidized block copolymer. The dehydration and drying methods are not particularly limited, and any method may be used.

The present invention is characterized in that the epoxidized block copolymer obtained as described above has an acid value of 10 mg KOH / g or less. Here, the acid value of the epoxidized block copolymer is necessary to neutralize the acids present in 1 g of the epoxidized block copolymer obtained by removing the solvent and drying after the epoxidation reaction. It is a value obtained by titration of the weight of different potassium hydroxide. Acids are mainly by-produced during the epoxidation reaction. For example, when peracetic acid is used as the epoxidizing agent, acetic acid is by-produced during the epoxidation reaction.

In addition, raw material impurities and acids derived from the various additives used in the production of the epoxidized block copolymer as described above can be determined by titration with potassium hydroxide. Included in the value of the acid value in the present invention. If the acid value is higher than 10 mgKOH / g, the amount of gelled product in the finally obtained epoxidized block copolymer will increase, and melt flow processability will deteriorate, which is not preferable.

In particular, when the epoxidized block copolymer and the other resin or rubber are melt-kneaded at a high temperature, if the acid value is high, a large amount of gelation product is formed during the melt-kneading,
It significantly affects the moldability of the composition. To reduce the acid value to 10 mgKOH / g or less, neutralize and / or wash with water the epoxidized block copolymer solution after the epoxidation reaction.
It can be achieved by removing the acid. Further, when steam stripping is carried out thereafter, since the acids are dissolved and removed in water at the same time when the solvent is subjected to steam distillation, those having a particularly low acid value can be obtained.

Typical examples of the alkaline aqueous solution used for neutralization include lithium hydroxide, sodium hydroxide,
Potassium hydroxide, calcium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, calcium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate,
Examples of the aqueous solution include sodium acetate, potassium acetate, aqueous ammonia and the like. The amount of alkali used is preferably a molar amount necessary for neutralizing the acids present in the reaction solution. If the amount of alkali is large, the epoxy ring will open, which is not preferable.

Further, if the amount of alkali is small, the acid remains, and the amount of gelled substance increases, which adversely affects the physical properties, which is not preferable. The washing with water may be carried out continuously or batchwise. In the case of a batch system, it is preferable to wash with 50 to 1000 parts by weight of water several times with respect to 100 parts by weight of the reaction crude liquid after epoxidation.

Particularly, when a large amount of epoxidizing agent is used, a corresponding amount of acids is by-produced, and it is preferable to remove the acids by increasing the number of times of washing with water. Upon washing with water, an inorganic salt such as sodium chloride or sodium sulfate may be added in order to improve the separation between the aqueous phase and the organic phase.

The molecular weight distribution of the epoxidized block copolymer obtained in the present invention is preferably 10 or less. The molecular weight distribution referred to here is the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene measured by GPC.
And the ratio (Mw / Mn).

The molecular weight distribution is preferably 5 or less,
More preferably, it is 3 or less. When the molecular weight distribution is larger than 10, the melt flowability of the resin is extremely poor and the moldability is poor, which is not preferable. The molecular weight distribution tends to have a large value as the amount of gelated product increases. The epoxidized block copolymer of the present invention, various additives, if necessary,
For example, anti-aging agent, cross-linking agent, heat stabilizer, UV absorber,
Alternatively, an inorganic filler such as silica, talc, or carbon, a plasticizer, and a softening agent such as oil can be blended and used.

The epoxidized block copolymer of the present invention is
The thermoplastic resin composition, the rubber-like polymer composition, the asphalt composition, and the adhesive composition have good moldability due to the properties derived from the specific skeletal structure and the small amount of gelation product. It can be used as a composition such as a product, a sealant composition, and a vibration damping composition. Furthermore, compatibilizers for resins, impact modifiers, latexes, emulsions,
It can be used for applications such as resin fillers.

The present invention will be shown below with reference to examples, but the present invention is not limited to these examples.

Example 1 Polystyrene-polybutadiene-polystyrene (SBS) block copolymer [manufactured by Nippon Synthetic Rubber Co., Ltd., trade name: TR-2000] 300 parts by weight was completely dissolved in 1500 parts by weight of ethyl acetate. , 30% of this peracetic acid
Continuously add 169 parts by weight of ethyl acetate solution and stir 40
The epoxidation reaction was carried out at ℃ for 3 hours. The reaction solution was returned to room temperature and washed with the same amount of pure water as the reaction solution three times to obtain an ethyl acetate solution of epoxidized polystyrene-polybutadiene-polystyrene polymer (ESBS). This solution was used as a surfactant with Emulgen PP-290 manufactured by Kao in 100 p water.
Add pm and perform steam stripping at a water temperature of 90 ° C by blowing steam from the bottom of the tank, 3-6
A crumb-shaped polymer having a diameter of mm was collected by filtration. This crumb was sent to a squeezing machine for dehydration, and then dried by a dryer. The acid value, epoxy equivalent, melt viscosity, molecular weight distribution, etc. of this polymer are shown in Table 1 together with the following examples.

[Example 2] The same as Example 1 except that after the completion of the epoxidation reaction, the reaction solution was washed with a 0.1N sodium hydrogen carbonate aqueous solution instead of being washed with pure water. ESBS was obtained by the method.

Example 3 ESBS was obtained in the same manner as in Example 1 except that the amount of the 30% ethyl acetate solution of peracetic acid used during epoxidation was changed to 422.5 parts by weight.

Example 4 A block copolymer of polystyrene-polybutadiene-polystyrene was added to a jacketed reactor equipped with a stirrer and a thermometer [Nippon Synthetic Rubber Co., Ltd.].
Product name: TR-2000] 300 parts by weight of cyclohexane 30
Dissolves in 00 parts by weight. As hydrogenation catalyst, 40 ml of di-p-tolylbis (1-cyclopentadienyl) titanium / cyclohexane solution (concentration 1 mmol / l) and 8 ml of n-butyllithium solution (concentration 5 mmol / l) were used at 0 ° C and hydrogen pressure of 2 Kg / cm2. The mixture obtained under the conditions was added to the above polymer solution and reacted at a hydrogen partial pressure of 2.5 kg / cm 2 for 30 minutes.

The solvent was removed from the obtained partially hydrogenated polymer solution by drying under reduced pressure to take out the polymer (the hydrogenation rate of the double bond derived from butadiene was 30%).

300 parts by weight of this partially hydrogenated block copolymer was dissolved in 1500 parts by weight of cyclohexane, 300 parts by weight of a 30% ethyl acetate solution of peracetic acid was continuously added dropwise thereto, and the mixture was stirred at 40 ° C. for 3 days. The epoxidation reaction was carried out for a time. The reaction solution was returned to room temperature and washed with the same amount of pure water as the reaction solution three times to obtain a solution of epoxidized partially hydrogenated polystyrene-polyisoprene-polystyrene copolymer (ESEBS). From this solution, the solvent was removed and the resin was recovered in the same manner as in Example 1.

[Example 5] A block copolymer of polystyrene-polyisoprene-polystyrene (SIS) [manufactured by Shell Kagaku Co., Ltd., trade name: Califlex TR1111] 300 parts by weight was dissolved in 1500 parts by weight of cyclohexane. 222 parts by weight of a 30% ethyl acetate solution of peracetic acid was continuously added dropwise,
The epoxidation reaction was carried out at 40 ° C. for 3 hours with stirring. The reaction solution was returned to room temperature and washed with the same amount of pure water as the reaction solution three times to obtain a solution of epoxidized polystyrene-polyisoprene-polystyrene polymer (ESIS). From this solution, Example 1
The solvent was removed and the resin was recovered in the same manner as in. Note 1 in Table 1: Epoxy equivalent indicates the value of 1600 / oxirane oxygen concentration (%).

The oxirane oxygen concentration was determined by titrating the weight% of the oxirane oxygen derived from the epoxy groups in the block copolymer with an acetic acid solution of hydrogen bromide. Note 2: Indicates the weight percentage of chloroform-insoluble matter in the epoxidized block copolymer (filtered with a 3 μm filter). Note 3: The value measured at 190 ° C with a flow tester (die φ1mm x 10mm, load 100kgf). Note 4: Indicates the value measured by GPC. Note 5: Shows the weight% of chloroform-insoluble matter in the epoxidized block copolymer after standing in an oven at 140 ° C for 20 minutes. (Below margin) Table 1 ABC D E F G Example 1 Water wash 1.4 470 <0.05 4850 1.15 <0.05 Example 2 Neutralization 0.8 470 <0.05 4820 1.15 <0.05 Example 3 Water wash 1.0 230 <0.05 18900 1.17 <0.05 Example 4 Water wash 1.3 295 <0.05 2050 1.21 <0.05 Example 5 Washing with water 1.3 360 <0.05 12300 1.20 <0.05 A: Acid removal method B: Acid value [mgKOH / g] C: Epoxy equivalent [1600 / oxirane oxygen (%)] Oxylan oxygen concentration is blocked The weight% of the oxirane oxygen derived from the epoxy group in the copolymer was determined by titration with a solution of hydrogen bromide in acetic acid.

D: Amount of gelation product [wt%] Shows the wt% of chloroform-insoluble matter in the epoxidized block copolymer. [Filtration with 3 micron filter] E: Melt viscosity [Poise] The value measured at 190 ° C. using a flow tester [die diameter 1 mm × 10 mm, load 100 kgf] is shown.

F: Molecular weight distribution [Mw / Mn], which is a value measured by GPC.

G: Gelation product after heating and kneading [% by weight] The epoxidized block copolymer was placed in an oven at 140 ° C.
The weight% of chloroform-insoluble matter in the copolymer after standing for 0 minutes is shown.

Comparative Example 1 A polymer was obtained in the same manner as in Example 1 except that the crude liquid for epoxidation reaction was not washed with water. The acid value of the obtained polymer was 15.2 mgKOH / g. The epoxy equivalent was 502, and some loss of epoxy groups was recognized.
The results of this test are summarized in Table 2 together with the comparative examples below. The test contents in Table 2 are the same as those described in the notes in Table 1.

[Comparative Example 2] In the method of Example 1, washing with water after the epoxidation reaction was not carried out, and the solvent was removed by the direct solvent removal method (0.1T) instead of the steam stripping method.
orr, 50 ° C., 2 hours) to obtain a polymer. The acid value of the obtained polymer was 40.3 mgKOH / g. The epoxy equivalent was 510, and a slight loss of the epoxy group was recognized.

Comparative Example 3 In the method of Example 1, the epoxidation reaction crude liquid was not completely washed with water, the acid was intentionally left, and the solvent was removed directly by the steam stripping method. The solvent was removed (0.1 Torr, 50 ° C., 2 hours) to obtain a polymer. The acid value of the obtained polymer was 21.5 mgKOH / g. The epoxy equivalent is 492.
And a slight loss of the epoxy group was recognized.

[Comparative Example 4] In the method of Example 3, washing with water after the epoxidation reaction was not carried out, and the solvent was removed by the direct solvent removal method (0.1T) instead of the steam stripping method.
orr, 50 ° C., 2 hours) to obtain a polymer. The acid value of the obtained polymer was 82.4 mgKOH / g. The epoxy equivalent was 270, and some loss of epoxy groups was recognized.

Comparative Example 5 A polymer was obtained in the same manner as in Example 4 except that the epoxidation reaction crude liquid was not washed with water in the method of Example 4. The acid value of the obtained polymer was 15.1 mgKOH / g. The epoxy equivalent was 330, and some loss of the epoxy group was recognized.
Through Comparative Examples 1 to 5, Example 1
The melt viscosity and the molecular weight distribution of the obtained polymer were larger than those of the above results. In particular, it can be seen that the amount of gelled product in the polymer after heating is significantly affected by the acid value. The formation of a large amount of these gelled substances is not preferable because it has a bad influence on molding processability. (Hereinafter blank) Table 2 B C D E F G Comparative Example 1 15.2 502 0.12 6500 1.34 5.50 Comparative Example 2 40.3 510 0.15 7100 1.36 7.30 Comparative Example 3 21.5 492 0.08 5500 1.28 6.05 Comparative Example 4 82.4 270 0.35 unmeasurable 1.35 80.8 Comparative Example 5 15.1 330 0.25 2200 1.34 4.90 BG is the same as the description in Table 1.

[0043]

By reducing the acid value, it is possible to obtain an epoxidized block copolymer having a low gel content and excellent moldability. Such an epoxidized block copolymer is particularly suitable for a composition with a thermoplastic resin or a rubber-like polymer, an asphalt composition, an adhesive, a resin filler, etc., in which a small amount of gel is formed particularly during heat-melt kneading. Can be used.

(The margin below)

Claims (1)

[Claims] 1. A block copolymer comprising a polymer block (A) mainly composed of a vinyl aromatic hydrocarbon compound and a polymer block (B) mainly composed of a conjugated diene compound, or a hydrogenated product thereof. An epoxidized block copolymer, characterized in that the epoxidized block copolymer obtained by epoxidation has an acid value of 10 mg KOH / g or less.