JPH07238207A - Block copolymer composition and adhesive composition - Google Patents

Abstract

PURPOSE:To obtain a composition useful for an adhesive, having low viscosity in melt processing and excellent heat resistance by blending specific two kinds of block copolymers synthesized by using a trifunctional coupling agent. CONSTITUTION:This block copolymer composition comprises (A) a block copolymer of the formula, (S-I-B)n-X and (2) a block copolymer of the formula, (S-I-B) (S is a polymer block of an aromatic prenyl compound; B is a butadiene polymer block; I is an isoprene polymer block; (n) is 3 or 4; X is a trifunctional or a tetrafunctional coupling agent residue) in the ratio of the component of A/B=20/80-90/10 by weight. An adhesive is obtained by blending 100 pts.wt. of the block copolymer composition with 50-300 pts.wt. of a tackifier. Styrene is used as the aromatic vinyl compound. Tetramethoxysilane or the like is preferably used as a coupling agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a block copolymer composition and a pressure-sensitive adhesive composition suitable for use as a pressure-sensitive adhesive. The present invention relates to a combined composition and a pressure-sensitive adhesive composition excellent in high holding power and heat resistance.

[0002]

2. Description of the Related Art Conventionally, styrene-isoprene-styrene (SIS) block copolymers and styrene-butadiene-styrene have been used as base polymers for pressure-sensitive adhesives (adhesives) and hot-melt adhesives (hot-melt adhesives). (SBS)
A thermoplastic elastomer such as a block copolymer is used, and a pressure-sensitive adhesive composition in which both a SIS block copolymer and an SBS block copolymer are used as a base polymer is also known (Japanese Patent Publication No. 53-42345). issue). Generally, in order to obtain a pressure-sensitive adhesive composition having high holding power, a branched block copolymer synthesized by using a polyfunctional coupling agent is used. As a method for efficiently obtaining such a branched SIS type block copolymer, styrene is polymerized in the presence of an organolithium initiator, and then isoprene is added for polymerization, and then a trace amount of butadiene is added. , A production method of forming a short butadiene polymer block at the polymerization end of an isoprene polymer block and then performing a coupling reaction using a polyfunctional coupling agent,
Recently reported (International Publication No. 92/20725)
issue). However, the pressure-sensitive adhesive composition using the branched block copolymer thus synthesized with a high coupling rate as a base polymer has a higher holding power, but the initial adhesive force is decreased, and the balance as a pressure-sensitive adhesive is improved. It lacks.

As a method for improving the balance as such an adhesive, a branched block copolymer and a linear block copolymer are often used in combination. For example, a polyfunctional coupling agent is used. A mixture of a branched block copolymer and a linear block copolymer (JP-A-51-26938), or a polyfunctional coupling agent and a bifunctional coupling agent were used in combination. A branched block copolymer mixture (JP-A-61-26647) has been tried.

However, conventionally known block copolymer type thermoplastic elastomers have poor thermal stability. For example, in the case of SIS type block copolymers, the viscosity of the melt is affected by heat deterioration during melt processing. Plummeted while SB
In the case of an S-type block copolymer, the viscosity of the melt rapidly increases due to cross-linking during melt processing. In addition, even in a blended system of both of these, the melt viscosity shows a sharp increase due to a change with time when heated. Therefore, the hot-melt pressure-sensitive adhesive using these block copolymers as the base polymer is difficult to ensure the stability of quality during processing and coating work,
Even if a mixture of a branched block copolymer and a linear block copolymer is used, low viscosity at the time of melt processing and high holding power as an adhesive are simultaneously satisfied, and further,
Improvement is required to obtain excellent heat resistance or low temperature characteristics.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a block copolymer composition having properties as a thermoplastic elastomer, low viscosity during melt processing, and excellent heat resistance. is there. Another object of the present invention is to provide a pressure-sensitive adhesive composition having good processability, high holding power, and excellent heat resistance. As a result of intensive studies to overcome the above-mentioned problems of the prior art, the inventors of the present invention have synthesized a (S-B-I) _3- X type block copolymer using a trifunctional coupling agent. (S-B-
It has been found that a mixture of the block copolymer of type I) in a specific ratio exhibits excellent low viscosity, and the present invention has been completed based on this finding.

[0006]

Thus, according to the present invention, the following [1] and [2] are provided. [1] A block copolymer (1) represented by the general formula (S-B-I) _n- X and a block copolymer (2) represented by the general formula (S-B-I). Contains, (1) and (2)
The weight of (1) / (2) = 20/80 to 90/10
(Weight ratio) is a block copolymer composition. (In the formula, S is a polymer block of an aromatic vinyl compound. B is a butadiene polymer block. I
Is an isoprene polymer block. n is 3 or 4. X is a residue of a trifunctional or tetrafunctional coupling agent. [2] A pressure-sensitive adhesive composition comprising 100 parts by weight of the block copolymer composition of [1] and 50 to 300 parts by weight of a tackifier.

The block copolymer (1) used in the block copolymer composition of the present invention has the general formula (S
-BI) a block copolymer represented by _n- X,
Polymer block S of aromatic vinyl compound, polymer block I of isoprene, and polymer block B of butadiene
A branched block copolymer having a structure obtained by coupling a polymerization active terminal of a (S-B-I) type block copolymer consisting of and with a trifunctional or tetrafunctional coupling agent. A polymer (wherein n is 3 or 4)
Is. X is the residue of the coupling agent).

The polystyrene-equivalent weight average molecular weight of the block copolymer (1) measured by gel permeation chromatography (GPC) is 50,000 to 50.
50,000, preferably 100,000 to 400,000
It is 0. When the molecular weight is less than the lower limit, the holding power of the obtained pressure-sensitive adhesive composition becomes insufficient, and when it exceeds the upper limit, the processability of the obtained pressure-sensitive adhesive composition becomes unsatisfactory.

S, B and I in the general formula are respectively
Including the case where the polymer block is substantially an aromatic vinyl compound block, the substantially butadiene polymer block, and the substantially isoprene polymer block. Here, “substantially” means that, when the units each contain a small amount of a bonding unit derived from another copolymerization component, B or I contains a small amount of a styrene unit in a gradually increasing ratio from one end to the other end of the block. It means the case where it is a tapered block polymer contained, or the case where at least part of B or I is modified by hydrogenation.

Examples of the aromatic vinyl compound used in the block copolymer (1) include styrene and α-
Methyl styrene, p-methyl styrene, m-methyl styrene, o-methyl styrene, p-tert-butyl styrene, dimethyl styrene, vinyl naphthalene, etc. can be mentioned. Of these, styrene is particularly preferable from the viewpoints of availability, reactivity, physical properties of the block copolymer, and the like.

The block copolymer (2) used in the block copolymer composition of the present invention has the general formula (S) as described above.
-B-I), which is a block copolymer obtained by block copolymerizing an aromatic vinyl compound, butadiene and isoprene.

The aromatic vinyl compound used in the block copolymer (2) includes the block copolymer (2)
Compounds similar to those used in the synthesis of are used.

The polystyrene reduced weight average molecular weight of the block copolymer (2) measured by gel permeation chromatography (GPC) is 10,000 to 30.
50,000, preferably 20,000 to 250,000
Is. When the molecular weight is less than the lower limit, the holding power of the obtained pressure-sensitive adhesive composition becomes insufficient, and when it exceeds the upper limit, the processability of the obtained pressure-sensitive adhesive composition becomes unsatisfactory.

Block copolymer (1) used in the present invention
In and (2), the proportion of the bound aromatic vinyl compound is 10 to 50% by weight, preferably 15 to 45% by weight, and the proportion of the bound butadiene is 10 to 60% by weight, preferably 15 to 45%. % Of bound isoprene, preferably 25 to 5% by weight.
It is 5% by weight.

When the proportion of the bound aromatic vinyl compound is less than 10% by weight, the holding power is lowered when the block copolymer is used as the base polymer of the pressure-sensitive adhesive, and conversely, when it exceeds 50% by weight, Tackiness (tackiness) is reduced. If the proportion of bound butadiene is less than 10% by weight, the melt viscosity of the block copolymer will decrease with time, and
The holding power decreases, and conversely, when it exceeds 60% by weight, the melt viscosity increases with time. The ratio of bound isopre is 10
If it is less than wt%, the melt viscosity of the block copolymer will increase with time, and if it exceeds 60 wt%, the melt viscosity will decrease with time and the holding power will decrease. When the ratio of bound styrene, bound butadiene and bound isoprene is within the above range, when the resulting block copolymer is used as a base polymer of a pressure-sensitive adhesive, both tackiness, adhesive strength and holding power are good, In addition, it is possible to obtain an adhesive having excellent low temperature characteristics. When the ratio of bound butadiene and bound isoprene is within the above range, a block copolymer having excellent heat resistance and having little change in melt viscosity during melt processing can be obtained.

Block copolymer (1) used in the present invention
In and (2), the proportion of 1,2-vinyl bonds in the butadiene portion is usually 15% or less and 3,4 in the isoprene portion is usually used.
-The proportion of vinyl bonds is 10% or less. Further, the block copolymers (1) and (2) used in the present invention usually have a storage elastic modulus (G ′) in viscoelasticity measurement of 0 ° C. to
In the range of 50 ° C., the peak of loss tangent (tan δ) at 10 ^{5 to} 3 × 10 ⁸ Pa and due to the butadiene polymer block and the isoprene polymer block is
There is only one in the range -80 ° C to -50 ° C. For example, S-I-S type block copolymer and S-B-
When the S-type block copolymer is blended, the peak of loss tangent (tan δ) due to each of the butadiene polymer block and the isoprene polymer block is
Two appear in the range of -80 ° C to -50 ° C. When the composition comprising the block copolymers (1) and (2) having a storage elastic modulus (G ') of less than 10 ⁵ Pa is used as the base polymer of the pressure-sensitive adhesive, the holding power is lowered and, conversely, 3 ×. 10
^If it exceeds ⁸ Pa, the tackiness decreases, which is not preferable.

Block copolymer used in the present invention (1)
The trifunctional or tetrafunctional coupling agent used for synthesizing is not particularly limited, and examples of the coupling agent include, for example, tin-based coupling agents such as methyltrichlorotin and tetrachlorotin; tetrachloride. Examples thereof include silicon halide-based coupling agents such as silicon and tetrabromosilicon; alkoxysilanes such as tetramethoxysilane; halogenated alkanes such as chloroform, trichloroethane, trichloropropane and tribromopropane. Among these, tetramethoxysilane and the like are preferable.

Block copolymer (1) used in the present invention
And (2) can be produced by a conventionally known method by using an organolithium compound as a polymerization initiator in a hydrocarbon solvent and sequentially polymerizing each polymer block. However, in each block copolymer represented by the general formula (1), after sequentially polymerizing the polymer block of S-B-I, the coupling reaction is performed by the coupling agent using the active terminal. Can be obtained.

The block copolymer represented by the general formula (1) is obtained by first polymerizing an aromatic vinyl compound in a hydrocarbon solvent using an organic lithium compound as a polymerization initiator, and then polymerizing butadiene and isoprene. Can be obtained by sequentially performing the polymerization of, then adding a trifunctional or tetrafunctional coupling agent, and performing a coupling reaction utilizing the active terminal.

Further, the block copolymer represented by the general formula (2) is obtained by first polymerizing an aromatic vinyl compound in a hydrocarbon solvent using an organic lithium compound as a polymerization initiator, and then polymerizing butadiene and isoprene. It can be obtained by sequentially performing the polymerization of.

The hydrocarbon solvent used for producing the block copolymer includes, for example, cyclopentane, cyclohexane, benzene, ethylbenzene, xylene, and a mixed solvent thereof with pentane, hexane, heptane, butane and the like. .

Examples of the organolithium compound used as the polymerization initiator include n-butyllithium and sec.
-Butyllithium, tert-butyllithium, n-hexyllithium, iso-hexyllithium, phenyllithium, naphthyllithium and the like can be mentioned, and usually used in the range of 0.01 to 1 part by weight per 100 parts by weight of the monomer.

The block copolymer composition of the present invention is obtained by separately synthesizing the block copolymers (1) and (2) and then mixing them in the above weight ratio by an arbitrary method. Also, when coupling a (S-B-I) type block copolymer having a polymerization active end of a polymer block of butadiene or isoprene, the type of trifunctional or tetrafunctional coupling agent It is also possible to obtain the block copolymer composition of the present invention at one time by controlling the amount and the amount thereof, and further by using a known coupling accelerator together if necessary.

The method of mixing the block copolymers (1) and (2) for obtaining the block copolymer composition of the present invention is not particularly limited, and a method of heating and mixing the respective components with a Brabender, a kneader or the like can be used. It can be illustrated.

The block copolymer composition of the present invention comprises: (1) between the weights of the block copolymers (1) and (2).
/ (2) = 20/80 to 90/10 (weight ratio), preferably (1) / (2) = 25/75 to 85/15 (weight ratio). (1) /
If (2) is less than 20/80 (weight ratio), the holding power as an adhesive decreases, which is not preferable. If (1) / (2) exceeds 90/10 (weight ratio), the adhesive strength, holding power, and heat resistance of the adhesive will be reduced, which is not preferable.

The block copolymer composition of the present invention can be used as a base polymer of an adhesive, and in particular,
It can be suitably used as a base polymer of a hot-melt pressure-sensitive adhesive composition by utilizing the properties and heat resistance of a thermoplastic elastomer. Such an adhesive composition comprises 100 parts by weight of the block copolymer composition and a tackifier 5
It contains 0 to 300 parts by weight. In addition, the softener 0-10
You may mix | blend in the ratio of 0 weight part.

The tackifier has a number average molecular weight of 30.
A low molecular weight resin having a softening point of 0 to 3,000 and a softening point of 60 to 130 ° C. based on the ring and ball method defined in JIS K-2207 can be preferably used. Specific examples include, for example, rosin and rosin derivatives, polyterpene resins, aromatic modified terpene resins and hydrides thereof, terpene phenol resins, coumarone indene resins, aliphatic petroleum resins, aromatic petroleum resins and hydrides thereof. , Aliphatic / aromatic copolymer petroleum resins, dicyclopentadiene petroleum resins and hydrides thereof, and low molecular weight polymers of styrene or substituted styrene.

As the tackifier, those which are compatible with the butadiene polymer block or the isoprene polymer block of the block copolymer are preferable, for example, polyterpene resin, aliphatic petroleum resin, aromatic petroleum resin hydride. Are preferred. Further, for the purpose of improving the cohesive force of the pressure-sensitive adhesive composition, a coumarone / indene resin or a low molecular weight polymer of styrene or substituted styrene compatible with the aromatic vinyl compound polymer block is mixed with the conjugated diene polymer block. You may mix with a melt | dissolving tackifier.

Examples of the softening agent include petroleum-based process oils such as paraffin-based process oil, naphthene-based process oil and aromatic process oil; castor oil,
Natural oils such as tall oil; dialkyl dialkyl salts such as dibutyl phthalate, dioctyl phthalate and dibutyl adipate; low molecular weight liquid polymers such as liquid polybutene and liquid polyisoprene. Among these, if paraffinic process oil or liquid polybutene is used,
It is possible to obtain a pressure-sensitive adhesive that is particularly stable against heat and ultraviolet rays and has an excellent color tone.

In the pressure-sensitive adhesive composition, the proportion of the tackifier used is 100 parts by weight of the block copolymer composition.
The amount is 50 to 300 parts by weight, preferably 30 to 180 parts by weight. If the proportion of the tackifier is less than 50 parts by weight, the tackiness is lowered, and conversely, if it exceeds 300 parts by weight, the holding power is lowered. The softening agent is used in an amount of 0 to 100 parts by weight, preferably 5 to 150 parts by weight, more preferably 10 parts by weight.
~ 130 parts by weight. If this ratio is deviated, it is difficult to obtain balanced physical properties as an adhesive. The rubber composition may be blended with other rubber components within a range that does not impair the object of the present invention, and further, if desired, may be blended with additives such as antioxidants, pigments and fillers as appropriate. be able to.

In the pressure-sensitive adhesive composition of the present invention, the general formula of the block copolymer used as the base polymer is
It is necessary to have a (S-B-I) _n- X type or a (S-B-I) type. A butadiene polymer block and a isoprene polymer block are in the reverse order of the general formula (S-IB) _n -X type, or (S-I-
When the block copolymer of type B) is used, it is not possible to obtain the adhesive property with high holding power and heat resistance.

The method for producing the pressure-sensitive adhesive composition is not particularly limited, and a mechanical mixing method using a roll, a Banbury mixer, a Dalton kneader, a melting pot equipped with a stirrer, or a uniaxial or biaxial Any method such as a hot-melt method characterized by heating and mixing using an extruder, a solvent method in which a blending component is put into a suitable solvent and a uniform solution of the pressure-sensitive adhesive composition is obtained by stirring the mixture. Can also be used. The pressure-sensitive adhesive composition is a solvent-free solution, or a solution thereof is uniformly applied to a support such as paper and a plastic film by using a suitable applicator, and if necessary, dried by various adhesive tapes or An adhesive sheet can be manufactured. The block copolymer composition of the present invention is excellent in heat resistance and has little change in melt viscosity with time during heating and melting. Therefore, pressure-sensitive adhesive compositions containing these as base polymers are particularly hot-melt pressure-sensitive adhesives. It can be suitably used as a composition. Since the hot-melt pressure-sensitive adhesive composition of the present invention has little change in melt viscosity with time even when the melting temperature is raised, it can be coated on a support with good fluidity without solvent by melting. Alternatively, the pressure-sensitive adhesive composition may be used as an adhesive or sealant by being fluidized by a method such as melting with heat or dissolving in a suitable solvent without being applied to a support.

The block copolymer composition of the present invention, in addition to the use of the above-mentioned pressure-sensitive adhesive composition, makes use of its characteristics,
For example, sheet film, injection molded products of various shapes, molded product applications such as hollow molded products, modifiers of various thermoplastic resins,
It is applicable to footwear materials, asphalt modifiers, wire cable materials, vulcanized rubber materials, vulcanized rubber modifiers, home appliances, automobile parts, industrial parts, household products, toys, etc. .

[0034]

EXAMPLES The present invention will be described more specifically below with reference to examples. The parts and% in the examples are based on weight unless otherwise specified. In addition, the measuring method of the physical property in the following examples is as follows. <Amount of bound styrene, amount of bound butadiene, amount of bound isoprene> It was measured by the NMR (nuclear magnetic resonance absorption) method (unit: wt%). <Weight Average Molecular Weight> The weight average molecular weight of the block copolymer is measured by high performance liquid chromatography (HCL-802A,
From the molecular weight distribution curve measured using
It was calculated based on a calibration curve obtained from the analysis results of standard polystyrene of known molecular weight. For the measurement, a column G-4000H and a column G-5000 filled with polystyrene gel were used in combination, the column temperature was 40 ° C., the carrier (tetrahydrofuran) flow rate was 1.3 m1 / min, and the sample concentration was 0.1.
It was measured under the condition of 6 g / 1 (unit: × 10 ⁴ ). Also,
The ratio of the block copolymer (1) to the block copolymer (2) in the block copolymer composition was determined from the peak area of each copolymer obtained by high performance liquid chromatography (unit: weight ratio ).

<Adhesive Properties> Preparation of Adhesive Composition An adhesive composition was prepared according to the following formulation and the adhesive properties were measured. Specifically, each component was kneaded with a Dalton kneader according to the following formulation, and the obtained composition was dissolved in toluene (nonvolatile content concentration 50%).
A pressure-sensitive adhesive tape was prepared by applying a paste having a thickness of 25 μm on a polyester film having a thickness of μm. The results are collectively shown in Table 1. [Composition of adhesive composition] Block copolymer composition 100 parts Tackifier (hydrogenated aromatic petroleum resin) 170 parts Softener (paraffinic process oil) 65 parts Antioxidant 1 part

(1) The initial adhesive strength is JIS Z-023.
In accordance with No. 7, at a temperature of 23 ° C. and 10 ° C., an adhesive tape having a length of 10 cm was attached to the slope of a stainless steel plate having an inclination angle of 30 degrees with the adhesive surface facing upward, and a diameter of 3/32 Steel balls of 30 sizes from inch to 32/32 inch are rolled at an initial speed of 0, and the size of the ball with the maximum diameter that stops on the adhesive tape is displayed (5
Average number of ball numbers). (2) Adhesive strength is 280 according to JIS Z-0237.
Width 10 mm on a stainless steel plate that has been polished with No. 1 water-resistant polishing paper
× Adhesive tape with a length of 100 mm is attached at 23 ° C.
Was measured by peeling in the direction of 180 degrees at a speed of 200 mm / min (unit: g / cm). (3) In accordance with JIS Z-0237, the holding power is such that an adhesive tape is attached to a stainless steel plate treated in the same manner as described above so that an area of 25 mm × 10 mm is in contact, and a load of 1 kg is applied at 50 ° C. The time required for falling off the stainless steel plate was measured (unit: min). (4) Heat resistance test (S.A.F.T .: Shear A)
dhesive Failure Template
re) A pressure-sensitive adhesive tape is attached to a stainless steel plate so that an area of 25 mm × 10 mm is in contact with it, heated at 40 ° C. for 1 hour, applied with a load of 1 kg, and heated at 0.5 ° C./minute to give The temperature when dropped was measured. The larger the value, the better the heat resistance (unit: ° C).

(Examples 1 to 3) In a 3 liter autoclave under a dry nitrogen atmosphere, 5.7 mmol of n-butyllithium was used as a polymerization initiator in 1500 g of a cyclohexane solvent, and styrene, butadiene, and isoprene were used. Are sequentially added to carry out polymerization, and thereafter, the amount of tetramethoxysilane used as a coupling agent is varied to carry out the coupling reaction, and shown in Table 1 (S-B-I).
The weight ratio of the _3- X type block copolymer to the (S-B-I) type block copolymer is 40/60, 60/40, 80/2.
0 block copolymer compositions were prepared. The bound styrene content of each of the obtained (S-B-I) ₃ -X type block copolymer and (S-B-I) type block copolymer was 30% by weight, and the proportion of bound butadiene was 21%. The ratio of weight% and bound isoprene is 49% by weight. Furthermore, the weight average molecular weight of the (S-B-I) _3- X type block copolymer was 210,000, and the weight average molecular weight of the (S-B-I) type block copolymer was 70,000. The weight average molecular weight of the block copolymer composition is shown in Table 1. Next, an adhesive composition was prepared using these three types of block copolymer compositions, and the adhesive physical properties were measured and the heat resistance test was performed. The results are shown in Table 1.

Examples 4 to 6 In a dry nitrogen atmosphere, in a 3 liter autoclave, using 5.7 mmol of n-butyllithium as a polymerization initiator in 1500 g of cyclohexane solvent, styrene, butadiene, and isoprene were used. Are sequentially added to carry out polymerization, and thereafter, the amount of tetramethoxysilane used as a coupling agent is varied to carry out the coupling reaction, and shown in Table 1 (S-B-I).
The weight ratio of the _3- X type block copolymer to the (S-B-I) type block copolymer is 40/60, 60/40, 80/2.
0 block copolymer compositions were prepared. The bound styrene content of each of the obtained (S-B-I) _3- X type block copolymer and (S-B-I) type block copolymer was 30% by weight, and the proportion of bound butadiene was 49. The weight% and the proportion of bound isoprene are 21% by weight. Furthermore, the weight average molecular weight of the (S-B-I) _3- X type block copolymer was 210,000, and the weight average molecular weight of the (S-B-I) type block copolymer was 70,000. The weight average molecular weight of the block copolymer composition is shown in Table 1. Next, an adhesive composition was prepared using these three types of block copolymer compositions, and the adhesive physical properties were measured and the heat resistance test was performed. The results are shown in Table 1.

Comparative Examples 1 and 2 Styrene, butadiene, and isoprene were prepared by using 5.7 mmol of n-butyllithium as a polymerization initiator in 1500 g of cyclohexane solvent in a 3 liter autoclave under a dry nitrogen atmosphere. Are sequentially added to carry out polymerization, and thereafter, the amount of tetramethoxysilane used as a coupling agent is varied to carry out the coupling reaction, and shown in Table 1 (S-B-I).
Two types of block copolymer compositions were prepared in which the weight ratio of the _3- X type block copolymer to the (S-B-I) type block copolymer was outside the range of the present invention. Obtained (SB
-I) The content of bound styrene in each of the _3- X type block copolymer and the (SB-I) type block copolymer is 30% by weight, the proportion of bound butadiene is 49% by weight, and the proportion of bound isoprene is Is 21% by weight. Furthermore, (S-
The weight average molecular weight of the B-I) ₃ -X type block copolymer is 2
The weight average molecular weight of the (S-B-I) type block copolymer was 70,000. The weight average molecular weight of the block copolymer composition is shown in Table 1. Then these three
An adhesive composition was prepared using various types of block copolymer compositions, and the adhesive properties were measured and the heat resistance test was performed. The results are shown in Table 1. (Comparative Example 3) Next, in a 3 liter autoclave under a dry nitrogen atmosphere, 5.7 mmol of n-butyllithium was used as a polymerization initiator in 1500 g of a cyclohexane solvent, and styrene, isoprene, and butadiene were sequentially added. After addition, polymerization was carried out, and thereafter, a coupling reaction was carried out using tetramethoxysilane as a coupling agent, and the (S-IB) ₃ -X type block copolymer shown in Table 1 and (S- A block copolymer composition comprising the IB) type block copolymer was produced. The bound styrene content of the obtained block copolymer composition was 30% by weight, the proportion of bound isoprene was 49% by weight, and the proportion of bound butadiene was 21% by weight. The weight average molecular weight of the (S-IB) ₃ -X type block copolymer is 216,000,
The weight average molecular weight of the (S-I-B) type block copolymer was 72,000. The weight average molecular weight of the block copolymer composition is shown in Table 1. Next, an adhesive composition was prepared using this block copolymer composition, and the adhesive properties were measured and the heat resistance test was conducted. The results are shown in Table 1.

(Comparative Example 4) Similarly, n-butyllithium was used as a polymerization initiator in a cyclohexane solvent, styrene, butadiene, and isoprene were sequentially added to carry out the polymerization, followed by coupling. A coupling reaction was performed using dibromobenzene as an agent, and the composition was composed of (S-B-I) _2- X type block copolymer and (S-B-I) type block copolymer shown in Table 1. A block copolymer composition was prepared. The obtained block copolymer composition had a bound styrene content of 30% by weight, a bound butadiene content of 49% by weight, and a bound isoprene content of 21% by weight. The (S-B-I) _2- X type block copolymer has a weight average molecular weight of 170,000, and
The weight average molecular weight of the I) type block copolymer was 70,000. The weight average molecular weight of the block copolymer composition is shown in Table 1. Next, an adhesive composition was prepared using this block copolymer composition, and the adhesive properties were measured and the heat resistance test was conducted. The results are shown in Table 1.

(Comparative Example 5) Further, similarly, styrene, butadiene, isoprene and styrene were sequentially added and polymerized to prepare an (S-B-I-S) type block copolymer. The obtained block copolymer had a bound styrene content of 30% by weight and a bound butadiene content of 21% by weight.
And the proportion of bound isoprene was 49% by weight.
The weight average molecular weight was 152,000. Next, an adhesive composition was prepared using this block copolymer composition, and the adhesive properties were measured and the heat resistance test was conducted. The results are shown in Table 1.

(Comparative Example 6) In the same manner, styrene, butadiene and styrene were sequentially added to carry out polymerization to obtain (S
-BS) type block copolymer was produced. The bound styrene content of the obtained block copolymer was 40% by weight, and the total content of bound butadiene and bound isoprene was 60% by weight. The weight average molecular weight was 148,000. Next, styrene, isoprene, and styrene were sequentially added and polymerized to produce a (S-I-S) type block copolymer. The obtained block copolymer had a bound styrene content of 15% by weight, a bound isoprene ratio of 85% by weight, and a weight average molecular weight of 150,000. The (S-B-S) type block copolymer thus produced and (S-I)
A pressure-sensitive adhesive composition was prepared using a block copolymer composition obtained by mixing the (S) type block copolymer at a ratio of 50/50 (weight ratio), and the pressure-sensitive adhesive property was measured and a heat resistance test was performed. The results are shown in Table 1.

[0043]

[Table 1]

As is clear from the results of Table 1, the pressure-sensitive adhesive compositions (Examples 1 to 6) using the block copolymer composition of the present invention have high holding power and good heat resistance. I know there is. On the other hand, a block copolymer composition in which the ratio of the (S-B-I) _3- X type block copolymer to the (S-B-I) type block copolymer is outside the range specified by the present invention is used. In the case of (Comparative Examples 1 and 2), the block copolymer composition which is a mixture of the (S-IB) _3- X type block copolymer and the (S-IB) type block copolymer was prepared. When used (Comparative Example 3), when using a block copolymer composition comprising a (S-B-I) _2- X type block copolymer and a (S-B-I) type block copolymer , (S-B-I-
When S) type block copolymer is used (Comparative Example 5),
The (S-B-S) type block copolymer and (S-I)
In the case of using a mixture with the -S) type block copolymer (Comparative Example 6), the balance of the adhesive physical properties was poor, and
It can be seen that the heat resistance is poor.

Specific embodiments of the present invention are as follows. (1) A block copolymer (1) represented by the general formula (S-B-I) _n- X and a block copolymer (2) represented by the general formula (S-B-I). Contains, (1) and (2)
The weight of (1) / (2) = 20/80 to 90/10
(Weight ratio) is a block copolymer composition. (In the formula, S is a polymer block of an aromatic vinyl compound. B is a butadiene polymer block. I
Is an isoprene polymer block. n is 3 or 4. X is a residue of a trifunctional or tetrafunctional coupling agent. (2) The block copolymer composition according to (1), wherein the aromatic vinyl compound is styrene. (3) The block copolymer composition of (1), wherein the proportion of the aromatic vinyl compound is 10 to 20% by weight, the proportion of the bound butadiene is 15 to 45% by weight, and the proportion of the bound isoprene is 20 to 70% by weight. (4) The block copolymer composition of (1), wherein n is 3. (5) The weight average molecular weight of the block copolymer of the general formula (1) is 10,000 to 500,000, and the weight average molecular weight of the general formula (2) is 10,000 to 300,000.
The block copolymer composition of (1), which is 0. (6) A pressure-sensitive adhesive composition obtained by mixing 100 parts by weight of the block copolymer composition of (1) and 50 to 300 parts by weight of a tackifier. (7) A pressure-sensitive adhesive composition comprising 100 parts by weight of the block copolymer composition of (1) and 80 to 180 parts by weight of a tackifier. (8) 100 parts by weight of the block copolymer composition of (1), 80 to 180 parts by weight of a tackifier, and 5 to 150 of a softening agent.
A pressure-sensitive adhesive composition containing 1 part by weight.

[0046]

EFFECTS OF THE INVENTION According to the present invention, there is provided a novel block copolymer composition having properties as a thermoplastic elastomer and having little change in melt viscosity with time during heating and melt processing and having excellent heat resistance. It The pressure-sensitive adhesive composition using the block copolymer composition having excellent heat resistance of the present invention as a base polymer is particularly useful as a hot-melt pressure-sensitive adhesive composition having high holding power and excellent heat resistance. .

Claims (2)

[Claims] 1. A block copolymer (1) represented by the general formula (S-B-I) _n- X and a block copolymer (2) represented by the general formula (S-B-I). And the weight of (1) and (2) is (1) / (2) = 20/80 to 90 /
The block copolymer composition is 10 (weight ratio). (In the formula, S is a polymer block of an aromatic vinyl compound. B is a butadiene polymer block. I is an isoprene polymer block. N is 3 or 4. X is trifunctional or tetrafunctional. It is the residue of the coupling agent.) 2. The block copolymer composition 10 according to claim 1.
A pressure-sensitive adhesive composition comprising 0 part by weight and 50 to 300 parts by weight of a tackifier.