JPH06279744A - Block copolymer composition and self-adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the compsn. which provides a self-adhesive excellent in adhesive strength an early stage, holding power, and capability of sealing corrugated cardboard by compounding specific block copolymers in a specified wt. ratio. CONSTITUTION:The compsn. contains a block copolymer expressed by the formula (A-B)nX (wherin A is an arom. vinyl polymer block; B is a conjugated diene polymer block; and X is a residue of a tri- or tetrafunctional alkoxysilane coupling agent)(I), a block copolymer expressed by the formula: (A-B)2Y (wherein Y is a residue of a difunctional halogenous coupling agent)(II), and a block copolymer expressed by the formula: (A-B) (III) in such wt. ratios that I/II is (10/90)-(50/50) and (I+II)/III is (85/15)-(95/5).

Description

Detailed Description of the Invention

[0002]

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, and more specifically, for a pressure-sensitive adhesive excellent in initial adhesive strength, holding power and cardboard sealability. And a pressure-sensitive adhesive composition obtained by using the block copolymer composition.

[0003]

2. Description of the Related Art Conventionally, various block copolymers such as polystyrene / polyisoprene block copolymers have been used as a base polymer for pressure-sensitive adhesive compositions. Although the adhesiveness is excellent, it is inferior in the holding power, and the branched block copolymer alone is excellent in the holding power, but the initial adhesive power is insufficient. Therefore, a branched block copolymer and a linear block copolymer are often used in combination.For example, a branched block copolymer and a linear block copolymer synthesized by using a polyfunctional coupling agent are used. A mixture with a combination (JP-A-51-26938), or a branched block copolymer mixture synthesized by using a polyfunctional coupling agent and a bifunctional coupling agent in combination (JP-A-61-
No. 26647) has been tried. However, among the performance requirements of the pressure-sensitive adhesive for packaging, the corrugated board sealing property is particularly important, but the above block copolymer mixture does not satisfy such performance requirements. The present applicant has already filed an application for a pressure-sensitive adhesive composition containing a specific branched block copolymer (Japanese Patent Application Laid-Open No. HEI 1)
-266156, JP-A-3-26747). However, the demand for adhesives with an excellent balance of various properties is becoming more and more advanced, and in particular, a balance between low-temperature initial adhesive strength when used in cold regions and thermal stability during heating and melting is maintained. At the same time, there is a demand for a material that exhibits excellent corrugated board sealing properties.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a block copolymer composition for obtaining a pressure-sensitive adhesive having a good balance between low-temperature adhesive strength and thermal stability during heating and melting, and particularly excellent in cardboard sealability. To get things. We have
As a result of earnest research on the composition of the block copolymer, it was found that the combined use of tetramethoxysilane and dibromobenzene as a coupling agent improves the thermal stability of the obtained block copolymer composition, and further It was found that the low-temperature characteristics were improved by reducing the ratio of the block copolymer, and the present invention was completed based on this finding.

[0005]

According to the present invention, the following (1) to (3) are provided. (1) The block copolymer (I) represented by the general formula (AB) nX, the block copolymer (II) represented by the general formula (AB) 2Y, and the general formula (II) And a block copolymer (III) represented by AB),
The weight of I) and (III) is (I) / (II) = 10
/ 90 to 50/50 and ((I) + (II)) / (I
II) = 85/15 to 95/5, wherein the block copolymer composition is characterized. (In the general formula, n = 3 or 4, A is a polymer block of an aromatic vinyl monomer, B is a polymer block of a conjugated diene monomer, and X is a trifunctional or tetrafunctional alkoxysilane. The residue of the compound-based coupling agent and Y represents the residue of the bifunctional halogen compound-based coupling agent.) (2) 100 parts by weight of the block copolymer composition of (1) and the tackifying resin 20 to An adhesive composition containing 200 parts by weight. (3) An adhesive for corrugated cardboard, which comprises the adhesive composition of (2).

The block copolymer (I) used in the block copolymer composition of the present invention has the general formula (A) as described above.
-B) a block copolymer represented by n X (in the general formula, n = 3 or 4), which is a polymer of a polymer block A of an aromatic vinyl monomer and a polymer of a conjugated diene monomer. A branch having a structure obtained by coupling the polymerization active terminal of the (AB) type block copolymer consisting of block B with a trifunctional or tetrafunctional alkoxysilane coupling agent. Block copolymer.

The proportion of the polymer block A of the aromatic vinyl monomer in the block copolymer (I) is 5 to 50% by weight,
It is preferably 10 to 45% by weight. If this proportion is less than 5% by weight, the holding force of the obtained pressure-sensitive adhesive composition will be lowered, and if this proportion exceeds 50% by weight, the initial adhesive force of the obtained pressure-sensitive adhesive composition will be lowered, which is not preferable.

The aromatic vinyl monomer for synthesizing the block copolymer (I) is not particularly limited,
Specific examples thereof include styrene, α-methylstyrene,
Examples thereof include vinyltoluene and vinylnaphthalene, with styrene being preferred.

The conjugated diene-based monomer for synthesizing the block copolymer (I) is not particularly limited, and specific examples thereof include 1,3-butadiene, isoprene,
2,3-dimethyl-1,3-butadiene, piperylene,
2,4-hexadiene and the like can be mentioned, but among them, 1,3-butadiene and isoprene are preferable.

The polystyrene reduced weight average molecular weight of the block copolymer (I) is 50,000 to 500,000,
It is preferably 100,000 to 400,000. 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.

The trifunctional or tetrafunctional alkoxysilane compound-based coupling agent used in the synthesis of the block copolymer (I) is not particularly limited. For example, as the trifunctional alkoxysilane compound-based coupling agent, phenyltriene is used. Methoxysilane, phenyltriethoxysilane, etc .; Tetramethoxysilane, tetraethoxysilane, etc. can be mentioned as the tetrafunctional alkoxysilane compound-based coupling agent. Above all, it is preferable to use tetramethoxysilane because it is possible to obtain a pressure-sensitive adhesive composition having an excellent balance of initial adhesive strength, holding power, corrugated board sealing property and processability.

The block copolymer (II) used in the block copolymer composition of the present invention has the general formula (AB) 2 Y
Polymerization of a block copolymer represented by the formula (A-B) consisting of a polymer block A of an aromatic vinyl monomer and a polymer block B of a conjugated diene monomer. It is a linear block copolymer having a structure obtained by coupling the active end with a bifunctional halogen compound-based coupling agent.

The proportion of the polymer block A of the aromatic vinyl monomer in the block copolymer (II) is 5 to 50.
%, Preferably 10 to 45% by weight. If this proportion is less than 5% by weight, the holding force of the obtained pressure-sensitive adhesive composition will decrease, and if this proportion exceeds 50% by weight, the initial adhesion of the obtained pressure-sensitive adhesive composition will decrease.

As the aromatic vinyl monomer and the conjugated diene monomer used in the block copolymer (II), the same monomers as those used in the synthesis of the block copolymer (I) are shown. be able to.

The polystyrene reduced weight average molecular weight of the block copolymer (II) is 50,000 to 500,000.
0, preferably 100,000 to 400,000. 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.

The bifunctional halogen compound-based coupling agent used in the synthesis of the block copolymer (II) is
For example, tin halide coupling agents such as dichlorotin, monomethyldichlorotin, dimethyldichlorotin, monoethyldichlorotin, diethyldichlorotin, monobutyldichlorotin, dibutyldibromotin, monohexyldichlorotin; dichlorosilane, monomethyldichlorotin. Silicon halide type such as chlorosilane, dimethyldichlorosilane, monoethyldichlorosilane, diethyldichlorosilane, monobutyldichlorosilane, dibutyldichlorosilane, monohexyldichlorosilane, dihexyldichlorosilane, dibromosilane, monomethyldibromosilane, dimethyldibromosilane Coupling agent; halogenated alkanes such as dichloroethane, dibromoethane, dibromomethane, dichloropropane, dibromopropane; dibromobenzene, etc. And halogenated aromatic compounds. Of these, halogenated aromatic compounds are preferable, and dibromobenzene is particularly preferable. To synthesize the block copolymer composition of the present invention, it is necessary to use both a trifunctional or tetrafunctional alkoxysilane compound-based coupling agent and a bifunctional halogen compound-based coupling agent. If any other combination of coupling agents is used, a block copolymer composition having good thermal stability cannot be obtained.

The block copolymer (III) used in the block copolymer composition of the present invention is a block copolymer represented by the general formula (AB), which is an aromatic vinyl monomer and a conjugated diene. It is obtained by block copolymerization with a system monomer.

The proportion of the polymer block A of the aromatic vinyl monomer in the block copolymer (III) is 5 to 50.
%, Preferably 10 to 45% by weight. If this proportion is less than 5% by weight, the holding force of the obtained pressure-sensitive adhesive composition will decrease, and if this proportion exceeds 50% by weight, the initial adhesion of the obtained pressure-sensitive adhesive composition will decrease.

The aromatic vinyl monomer and the conjugated diene-based monomer used in the block copolymer (III) include
The same monomers as those used for the synthesis of the block copolymer (I) are used.

The polystyrene reduced weight average molecular weight of the block copolymer (III) is 10,000 to 300,000.
It is 0, preferably 20,000 to 250,000. When the molecular weight is less than the above lower limit, the holding power of the obtained pressure-sensitive adhesive composition becomes insufficient, and when it exceeds the above upper limit, the processability of the obtained pressure-sensitive adhesive composition becomes unsatisfactory.

The block copolymer composition of the present invention has a ratio (I) / (II) = 10/9 between the weights of the block copolymers (I), (II) and (III) contained therein.
0-50 / 50 and ((I) + (II)) / (II
I) = 85/15 to 95/5 needs to be established. If it is out of this range, the low-temperature initial adhesive strength and corrugated board sealability of the obtained pressure-sensitive adhesive composition are deteriorated, and the balance with other pressure-sensitive adhesive properties such as holding power becomes unsatisfactory, which is not preferable.

Within the range not impairing the effects of the present invention, 5% by weight or less of the block copolymer composition is a block copolymer other than the block copolymers (I) to (III), natural rubber, butadiene rubber, It can be replaced by other polymers such as isoprene rubber.

In the block copolymer composition of the present invention, the block copolymers (I), (II) and (III) are separately synthesized and then mixed in the above weight ratio by an arbitrary method. May be obtained by
Coupling at the time of coupling an (AB) type block copolymer in which a polymer block of a conjugated diene monomer having a polymerization active terminal is directly bonded to a polymer block of an aromatic vinyl monomer. The block copolymers (I) to (II) can be controlled by controlling the type and amount of the agent and, if necessary, using a known coupling accelerator together.
It can also be obtained by obtaining a block copolymer mixture comprising any two components of I) and appropriately mixing these. Furthermore, according to the latter method, the block copolymer composition of the present invention can be obtained at one time.

The method of mixing the block copolymers (I) to (III) 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 method for synthesizing the block copolymer (I) used in the present invention is not particularly limited,
For example, the following processes (a) to (d) can be mentioned according to the method described in JP-A-3-26747.
That is, (a) First, an aromatic vinyl monomer is polymerized with a monolithium initiator in a solvent containing a polar compound. As the monolithium initiator, known ones capable of initiating polymerization of an aromatic vinyl monomer and a conjugated diene monomer can be used, and methyllithium, n-propyllithium, n-butyllithium, sec-butyllithium. And the like are shown as typical examples thereof, but n-butyllithium is particularly preferable. The amount of the monolithium initiator used can be calculated by a method well known to those skilled in the art according to the molecular weight of the desired polymer.

The polymerization solvent is not particularly limited as long as it is inert to the monolithium initiator.
An open chain hydrocarbon solvent, a cyclic hydrocarbon solvent or a mixed solvent thereof is used. As the open chain hydrocarbon solvent, n-butane, isobutane, or a mixture thereof; 1-butene, isobutylene, trans-2-butene, cis-2-
Butene or a mixture thereof, 1-pentene, trans-2-pentene, cis-2-pentene or a mixture thereof; n-pentane, isopentane, sec-pentane or a mixture thereof; 1-pentene, trans-2-pentene Examples include open chain alkanes and alkenes having 4 to 5 carbon atoms such as cis-2-pentene and mixtures thereof. Specific examples of the cyclic hydrocarbon solvent include aromatic compounds such as benzene, toluene and xylene; and alicyclic hydrocarbons such as cyclohexane. From the viewpoint of controlling the polymerization temperature and controlling the molecular weight distribution of the polymer block of the aromatic vinyl monomer, the open-chain hydrocarbon solvent having 4 to 5 carbon atoms and the cyclic hydrocarbon solvent are in a weight ratio of 5:95 to 50. It is preferable to use it as a mixed solvent in the range of: 50, preferably in the range of 10:90 to 40:60.

It is not essential to use a polar compound, but by using it, the polymerization initiation rate can be adjusted, the vinyl content of the polymer of the conjugated diene monomer can be adjusted,
The molecular weight distribution of the polymer block of the aromatic vinyl monomer can be adjusted. As the polar compound, in the copolymerization of a conjugated diene-based monomer or an aromatic vinyl monomer with a monolithium initiator, among known polar compounds used as a vinyl content modifier or randomizer, a relative dielectric Aromatic or aliphatic ethers or tertiary amines with a ratio of 2.5 to 5.0 can be used. Specific examples of such polar compounds include aromatic ethers such as diphenyl ether and anisole; aliphatic ethers such as diethyl ether and dibutyl ether;
Tertiary monoamines such as erymethylamine, triethylamine, and tripropylamine are mentioned.
One kind or two or more kinds are used. A preferable amount of the polar compound used in order to make the molecular weight distribution of the polymer block of the aromatic vinyl monomer to be a predetermined value and to make the characteristics of the pressure-sensitive adhesive composition containing the obtained block copolymer excellent. Is in the range of 0.1 to 100 mol, and more preferably 0.5 to 20 mol, per mol of the monolithium initiator.

The method for polymerizing the aromatic vinyl monomer is not particularly limited, and batch polymerization in which the total amount of the aromatic vinyl monomer and the total amount of the initiator are charged in a batch polymerization system and reacted, and these are continuously polymerized Continuous polymerization in which reaction is performed while being supplied to the system
Any of commonly used methods, such as a method in which polymerization is carried out to a predetermined conversion rate using a part of the monomer and the initiator and then the remaining monomer and the initiator are added to continue the polymerization, You may use. The polymerization is usually 0 ° C to 90 ° C, preferably 2 ° C.
It is carried out in the range of 0 ° C to 70 ° C. When it is difficult to control the reaction temperature, it is preferable to control the temperature by reflux cooling using a reaction vessel equipped with a reflux condenser.

(B) Next, a conjugated diene monomer is added to the polymerization system in which the polymer block A of the aromatic vinyl monomer having a polymerization active terminal is present to carry out polymerization. The conjugated diene-based monomer is preferably added continuously in order to control the reaction heat, but an addition method other than this may be adopted. Thus, an (AB) type block copolymer in which the polymer block B of the conjugated diene-based monomer having a polymerization active terminal is directly bonded to the polymer block A of the aromatic vinyl monomer is produced.

(C) After the completion of the polymerization reaction of the conjugated diene-based monomer, a coupling agent is added to the polymerization system to bond the (AB) type block copolymer having an active terminal, Target general formula (AB) _n X (where n =
3 or 4, A is a polymer block of an aromatic vinyl monomer, B is a polymer block of a conjugated diene monomer, and X is a residue of a trifunctional or tetrafunctional alkoxysilane compound-based coupling agent. A block copolymer represented by the formula (1) is obtained. At this time, a known coupling accelerator may be added.

(D) After completion of the coupling reaction, if necessary, water, alcohol, acid or the like is added to deactivate the polymerization active species, and if necessary, an antioxidant is added, followed by a known polymer separation method. The polymer is separated by (for example, steam stripping), and the desired branched block copolymer, or a mixture of this and a linear diblock copolymer, is obtained through a drying step.

The block copolymer (II) used in the present invention is synthesized in the same manner as the block copolymer (I) except that the coupling agent used in the step (c) is changed.

The block copolymer (III) used in the present invention is a conjugated diene-based monomer having a polymerization active terminal in the same manner as in the synthesis processes (a) and (b) of the block copolymer (I). Linear polymer block B directly bound to the polymer block A of the aromatic vinyl monomer (A-
After obtaining the B) type block copolymer, the polymerization active species are deactivated as in the above process (d), and if necessary, an antioxidant is added, followed by separation and drying without performing a coupling reaction. It can be obtained through steps.

In order to obtain only the block copolymer (I) used in the present invention in a high yield, the trifunctional or tetrafunctional compound is used.
The optimal amount of the functional alkoxysilane compound-based coupling agent used is 1/3 mol based on 1 mol of the monolithium initiator used for the polymerization. If the amount used is more than 1/3 mol, the second component co-produces, but if the amount is further increased, the residue of the coupling agent is present at the end (AB-
X) a linear block copolymer having the structure
A, B, and X are the same as the above), and a large amount is generated. The linear block copolymer having a structure of (A-B-X) having a coupling agent residue at the terminal easily hydrolyzes in the block copolymer production process, is difficult to steam solidify, and gels. In the present invention, the amount of the trifunctional or tetrafunctional coupling agent used is preferably 0.375 mol or less with respect to 1 mol of the monolithium initiator because some problems such as easiness occur.

When the method for temporarily obtaining the block copolymer composition of the present invention as described above is adopted, the block copolymer obtained by the type and amount of the coupling agent and the coupling accelerator used. Since the composition of the coalesced mixture is different, it is recommended to conduct a preliminary experiment to determine the kind and the optimum amount to be used. Usually, the amount of the coupling agent is 0.15 per mol of the monolithium initiator.
The amount of the coupling accelerator is preferably selected from the range of 0.375 mol to 0.375 mol and the range of 2 to 12 mol per mol of the coupling agent.

The pressure-sensitive adhesive composition of the present invention comprises the block copolymer composition of the present invention and a tackifying resin. As the tackifying resin to be used, conventionally known resins can be used. Specifically, rosins; modified rosins such as disproportionated rosins and duplex rosins; glycols, glycerin,
Esters of polyhydric alcohols such as pentaerythritol and rosins or modified rosins; terpene resins; aliphatic, aromatic, alicyclic or aliphatic-aromatic copolymer hydrocarbon resins or these Hydride; phenol resin; coumarone-indene resin and the like.
A particularly preferred tackifying resin is an aliphatic or aliphatic-aromatic copolymer hydrocarbon resin which has good compatibility with the block copolymer composition of the present invention. The amount of tackifying resin used is 20 to 2 per 100 parts by weight of the block copolymer composition.
00 parts by weight, preferably 50 to 150 parts by weight.

If desired, a softening agent (plasticizer), an antioxidant, a heat stabilizer, an ultraviolet absorber, a filler and other compounding agents may be added to the pressure-sensitive adhesive composition of the present invention. As the softening agent, conventionally known aromatic, paraffinic or naphthene-based extender oils (extender oils), which are used in adhesives, liquid polymers such as polybutene and polyisobutylene can be used. The amount of the softening agent used is usually 100 parts by weight or less per 100 parts by weight of the block copolymer composition. 2,6-di-t as an antioxidant
hindered phenolic compounds such as ert-butyl-p-cresol and di-tert-butyl-4-methylphenol; thiodicarboxylate esters such as dilaurylthiopropionate; tris (nonylphenyl) phosphite Phosphites and the like are used alone or as a mixture.

The method of mixing the block copolymer composition of the present invention with a tackifying resin and other various additives is not particularly limited. Examples thereof include a method of dissolving each component in a solvent and uniformly mixing it, and then removing the solvent by heating or the like, and a method of heating and melting and mixing each component with a kneader or the like.

The pressure-sensitive adhesive composition of the present invention comprises n-hexane,
It can be used as a solution-type pressure-sensitive adhesive which is dissolved in cyclohexane, benzene, toluene or the like, an emulsion-type pressure-sensitive adhesive which is dispersed in water using an emulsifier, or a solventless hot-melt pressure-sensitive adhesive. Particularly when used as a hot melt type adhesive, it is suitable as an adhesive for corrugated board sealing, and an adhesive tape obtained by applying the adhesive on a suitable substrate such as polyester film has excellent performance as an adhesive tape for corrugated board. Exert.

[0040]

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 this example, the molecular weight of the polymer is a polystyrene-equivalent weight average molecular weight determined by high performance liquid chromatography using tetrahydrofuran as a carrier. Furthermore, the composition of the copolymer was determined from the peak area of each copolymer obtained by high performance liquid chromatography.

<Melt Viscosity> Using a flow tester, the load was measured at 10 kg and 160 ° C. (unit: × 10).
^-4 cps). <Adhesive Physical Properties> Nonvolatile Content Concentration of Block Copolymer Composition 5
A 0% pressure-sensitive adhesive solution was prepared, and this solution was applied onto a 25 μm-thick polyester film so that the adhesive thickness was 25 μm to prepare a pressure-sensitive adhesive tape, and the obtained adhesive tape had an initial adhesive force, adhesive force, and holding property. The force and corrugated board sealability were measured. (1) The initial adhesive strength is 2 according to JIS Z-0237.
At 3 ° C and 10 ° C, a 10 cm long adhesive tape was attached to a slope on a stainless steel plate having an inclination angle of 30 degrees with the adhesive side facing upward, and a diameter of 3 cm from a position 10 cm above the slope.
Steel balls of 30 types from / 32 inch to 32/32 inch are rolled at an initial speed of 0 and displayed as the size of the ball with the maximum diameter that stops on the adhesive tape (average of 5 ball numbers. value). (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. to obtain an adhesive tape. The time required for falling off the stainless steel plate was measured (unit: min). (4) According to the method described in Japanese Utility Model Laid-Open No. 58-37549, two corrugated boards having a width of 50 mm are arranged in parallel at a slight interval in accordance with the method described in Japanese Utility Model Laid-Open No. 37549/1983, and the corrugated board is centered at the interval. Adhere the adhesive tape cut into a width of 25 mm and a length of 50 mm, attach it with the attachment surface on the lower side, put a cone-shaped weight of 500 g on the upper side, and measure the time until the adhesive tape causes interface breakage Then, the MTTF (mean failure life) obtained from this is displayed. The larger the numerical value of each of these characteristics, the better (unit: minutes).

Reference Example Synthesis of Block Copolymer (1) In a dry nitrogen atmosphere, in a 3 liter autoclave, 5.7 mmol of n-butyllithium was used as a polymerization initiator in 1500 g of cyclohexane solvent, and 6
Polymerization was carried out by sequentially adding 60 g of styrene and 368 g of isoprene at 0 ° C. for 5 hours, and then 0.1 mol of tetramethoxysilane was added to 1 mol of n-butyllithium as a coupling agent to form a cup. The ring reaction was carried out to produce the (AB) 3-X type block copolymer (block copolymer (I)) shown in Table 1. (2) 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 6
Polymerization was carried out by sequentially adding 60 g of styrene and 368 g of isoprene at 0 ° C. for 5 hours, and thereafter, as a coupling agent, 0.38 mol of dibromobenzene was added to 1 mol of n-butyllithium, followed by capping. The ring reaction was carried out to produce the (AB) 2-X type block copolymer (block copolymer (II)) shown in Table 1. (3) 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,
60 g of styrene and 368 g of isoprene were sequentially added at 0 ° C. for 5 hours to carry out polymerization to produce an (AB) type block copolymer (block copolymer (III)) shown in Table 1. Table 1 shows the weight average molecular weight (unit: × 10 ^-4 ) and the composition of each of styrene and isoprene (unit: wt%) of each of the obtained block copolymers (I) to (III).

[0043]

[Table 1]

(Examples 1 to 6 and Comparative Examples 1 to 6) Using the block copolymers (I) to (III) produced in Reference Examples, block copolymer compositions having weight ratios shown in Table 2 were prepared. Then, for these block copolymer compositions, an adhesive composition was prepared by the following formulation and the adhesive physical 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%), and this solution was applied onto a 25 μm thick polyester film. To a thickness of 25 μm to prepare an adhesive tape. The results are collectively shown in Table 2. [Blending of pressure-sensitive adhesive composition] Block copolymer composition 100 parts Tackifier (hydride of aromatic petroleum resin) 100 parts Softener (paraffin-based process oil) 20 parts Antioxidant 1 part

[0045]

[Table 2]

From Table 2, it can be seen that the pressure-sensitive adhesive composition using the block copolymer composition of the present invention has a good balance of pressure-sensitive adhesive performance, and particularly excellent corrugated board sealing property.

(Example 7 and Comparative Examples 7 to 8) Block copolymers (I) to (III) were synthesized in the same manner as in Reference Example by using the combination of coupling agents shown in Table 3 and A thermal stability test was performed on the block copolymer composition having the weight ratio shown in Table 4 prepared using Further, a pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 using the block copolymer composition subjected to the thermal stability test, and the pressure-sensitive adhesive properties were measured. The results are shown in Table 3. (Thermal stability test) The melt viscosity of the block copolymer composition was measured with a flow tester under a load of 10 kg,
It was measured at 0 ° C (unit: × 10 ^-4 cps). Next, after heating the block copolymer composition at 180 ° C. for 2 hours, the flow tester is used again to apply a load of 10 kilograms, 180
The melt viscosity was measured at ° C (unit: × 10 ^-4 cps), and the change rate (unit:%) of the melt viscosity after heating with respect to the melt viscosity before heating was determined.

[0048]

[Table 3]

From the results shown in Table 3, the thermal stability of the pressure-sensitive adhesive composition comprising a block copolymer synthesized by using an alkoxysilane compound-based coupling agent and a halogen compound-based coupling agent as the coupling agent of the present invention is particularly high. It can be seen that it is excellent and exhibits high performance without deterioration of corrugated board sealing property even when subjected to heat treatment.

Specific embodiments of the present invention are as follows. (1) The block copolymer (I) represented by the general formula (AB) nX, the block copolymer (II) represented by the general formula (AB) 2Y, and the general formula (II) And a block copolymer (III) represented by AB),
The weight of I) and (III) is (I) / (II) = 10
/ 90 to 50/50 and ((I) + (II)) / (I
II) = 85/15 to 95/5, wherein the block copolymer composition is characterized. (In the general formula, n = 3 or 4, A is a polymer block of an aromatic vinyl monomer, B is a polymer block of a conjugated diene monomer, and X is a trifunctional or tetrafunctional alkoxysilane. The residue of the compound coupling agent, Y represents the residue of the bifunctional halogen compound coupling agent.) (2) The aromatic vinyl monomer is styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene. The conjugated diene-based monomer is selected from 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, piperylene, and 2,4-hexadiene (1). Block copolymer composition. (3) The polystyrene reduced weight average molecular weight of the block copolymer (I) is 50,000 to 500,000, and the polystyrene reduced weight average molecular weight of the block copolymer (II) is 50,000 to 500,000. The block copolymer composition according to (1), wherein the block copolymer (III) has a polystyrene reduced weight average molecular weight of 10,000 to 300,000. (4) Polymer of aromatic vinyl monomer of block copolymer (I) The proportion of block A is 5 to 50% by weight, and the polymer of aromatic vinyl monomer of block copolymer (II) Block A of (1), wherein the proportion of Block A is 5 to 50% by weight, and the proportion of Block A of the polymer of aromatic vinyl monomer of Block Copolymer (III) is 5 to 50% by weight. Composition. (5) The block copolymer composition according to (1), wherein the trifunctional or tetrafunctional alkoxysilane compound-based coupling agent is tetramethoxysilane, and the bifunctional halogen compound-based coupling agent is dibromobenzene. (6) An adhesive composition comprising 100 parts by weight of the block copolymer composition of (1) and 20 to 200 parts by weight of a tackifying resin. (7) An adhesive for corrugated cardboard, which comprises the adhesive composition of (6).

[0051]

As described above, according to the present invention, it is possible to obtain a block copolymer composition having an excellent balance of initial adhesive strength, holding power, corrugated board sealing property and processability as compared with the prior art. An excellent pressure-sensitive adhesive composition can be obtained by combining with a tackifying resin.

Claims (3)

[Claims] 1. A block copolymer (I) represented by the general formula (AB) n X, a block copolymer (II) represented by the general formula (AB) 2 Y, and A block copolymer (III) represented by the formula (AB), (I),
The weight of (II) and (III) is (I) / (II) =
10/90 to 50/50 and ((I) + (II)) /
(III) = 85/15 to 95/5, wherein the block copolymer composition is characterized. (In the general formula, n = 3 or 4, A is a polymer block of an aromatic vinyl monomer, and B is
Is a polymer block of a conjugated diene monomer, X is a residue of a trifunctional or tetrafunctional alkoxysilane compound coupling agent, and Y is a residue of a difunctional halogen compound coupling agent. . ) 2. The block copolymer composition 10 according to claim 1.
An adhesive composition comprising 0 parts by weight and 20 to 200 parts by weight of a tackifying resin. 3. An adhesive for corrugated cardboard, which comprises the adhesive composition according to claim 2. [0001]