JPH01266156A - Block copolymer composition for self-adhesive and self-adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the title copolymer composition excellent in initial adhesive power, holding power, flexibility, workability, and heat stability, by mixing a specified block copolymer having three branched chains with a specified linear diblock copolymer. CONSTITUTION:The title block copolymer composition is prepared by mixing 50-95wt.% block copolymer having three branched chains, represented by the formula (A-B)3X (wherein A is a polymer block of an aromatic vinyl monomer; B is a polymer block of a conjugated diene monomer; X is a trifunctional or tetrafunctional silane coupling agent residue), in a weight ratio of the polymer block A to the polymer block B of 10:90-30:70, with 50-5wt.% linear diblock copolymer represented by the formula C-I (wherein C is a polymer block of an aromatic vinyl monomer; I is an isoprene polymer block), in a weight ratio of the polymer block C to the polymer block I of 5:95-30:70. This copolymer composition has excellent initial adhesive power, holding power, flexibility, workability, and heat stability; by combining it with a tackifier resin, an excellent self-adhesive composition can be obtained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a block copolymer composition and a pressure-sensitive adhesive composition suitable for use in pressure-sensitive adhesives, and more specifically to initial adhesive strength, holding power, and flexibility. , a block copolymer composition comprising a tri-branched block copolymer and a linear diblock copolymer of a specific composition, which have excellent processability and thermal stability, and an adhesive composition obtained using the same. in between.

(Prior art) Various block copolymers, including polystyrene/polyisoprene block copolymers, have been used as base polymers for pressure-sensitive adhesive compositions, but linear block copolymers alone have an initial Although radial block copolymers have excellent adhesion, they have poor retention, and radial block copolymers alone have excellent retention but insufficient initial adhesive strength, so radial block copolymers and linear block copolymers are mixed together. Often used (for example, JP-A-51-269)
38, Japanese Patent Publication No. 61-26647). However, it has not yet been possible to find a pressure-sensitive adhesive that simultaneously satisfies various properties other than initial adhesion and holding power, such as flexibility, processability, and thermal stability. Not yet.

(Problems to be Solved by the Invention) An object of the present invention is to obtain an adhesive having an excellent balance of the above properties and a block copolymer composition for obtaining the same. As a result of intensive research to achieve the above object, the present inventors found that by using a block copolymer composition having a specific composition, initial adhesion strength, holding power, flexibility, processability, and thermal stability can be improved in a well-balanced manner. We discovered that we can improve the
Based on this knowledge, we have completed the present invention.

(Means for Solving the Problems) Thus, according to the present invention, general formula (I) (A-B) 3X
(In the formula, A is a polymer block of aromatic vinyl monomer,
B is a polymer block of a conjugated diene monomer, X is a residue of a silane trifunctional or tetrafunctional coupling agent), and the polymer block A and the polymer block B are 50 to 95% by weight of a tri-branched block copolymer having a weight ratio of 10/90 to 30/70, and general formula (II)
It is represented by cr (in the formula, C represents a polymer block of aromatic vinyl monomer, and ■ represents an isoprene polymer block), and the weight ratio of polymer block C and polymer block ■ is 5/ Linear block copolymer 5, which is 95 to 30/70
0 to 5% by weight of a block copolymer composition for adhesives, and 100 parts by weight of this block copolymer composition for adhesives and 10 to 150 parts by weight of tackifying resin.
Parts by weight of an adhesive composition are provided.

The tri-branched block copolymer, which is the first component of the block copolymer composition of the present invention, is composed of a polymer block A of an aromatic vinyl monomer and a polymer block A of a conjugated diene monomer having a polymerization active terminal. It is a tri-branched block copolymer having a structure in which an A-B block copolymer consisting of a combined block B is coupled with a silane-based trifunctional or tetrafunctional coupling agent.

The aromatic vinyl monomer used in the tri-branched block copolymer used in the present invention is not particularly limited, and specific examples thereof include styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, etc. Among them, styrene is preferred.

The conjugated diene monomer used in the tri-branched block copolymer used in the present invention is not particularly limited, and specific examples thereof include 1,3-butadiene, isoprene, 2,3-dimethyl-1 , 3-butadiene, piperylene, 2,4-hexadiene, etc., among which 1,3-butadiene and isoprene are preferred.

In the tribranched block copolymer used in the present invention, the proportion of the polymer block A of aromatic vinyl monomers is 10 to 30% by weight, preferably 12 to 22% by weight. If this proportion is less than 10% by weight, the holding power of the obtained block copolymer will be reduced, and if this proportion exceeds 30% by weight, the initial adhesive strength and flexibility of the obtained block copolymer will be reduced.

The weight average molecular weight of the tri-branched block copolymer used in the present invention is 125.000 to 125.000.
400. It's OOO. If the molecular weight is below the above-mentioned lower limit, the holding power of the obtained block copolymer will be insufficient, and if it is above the above-mentioned upper limit, the processability of the obtained block copolymer will be unsatisfactory.

The coupling agent used in the tribranched block copolymer used in the present invention is a silane-based trifunctional or tetrafunctional coupling agent.

Even if coupling agents other than these are used, the object of the present invention, which is to obtain a pressure-sensitive adhesive composition with an excellent balance of initial adhesive strength, holding power, flexibility, processability, and thermal stability, cannot be achieved.

Specific examples of silane-based trifunctional coupling agents include:
Methyltrichlorosilane, phenyltrichlorosilane,
Ethyltrichlorosilane, tertiary-butyltrichlorosilane, methyltribromodilane, etc., and specific examples of silane-based tetrafunctional coupling agents include silicon tetrachloride, silicon tetrabromide, tetramethoxysilane, etc. However, the coupling agent is not limited thereto as long as it is a trifunctional or tetrafunctional coupling agent having a silicon atom.

Next, the linear diblock copolymer represented by general formula (II) C-■, which is the second component of the block copolymer composition of the present invention, blocks the aromatic vinyl monomer and isoprene. Obtained by copolymerization.

In the present invention, it is important to use isoprene in the synthesis of the linear diblock copolymer, and 1.
Even if 1,3-conjugated diene monomers such as 3-butadiene and piperylene are used, the effects of the present invention cannot be obtained.

The aromatic vinyl monomer used in the synthesis of the linear diblock copolymer used in the present invention is not particularly limited, and specific examples thereof include styrene, α-methylstyrene, vinyltoluene, vinyl Examples include naphthalene, among which styrene is preferred.

The proportion of polymer block C of aromatic vinyl monomer in the linear diblock copolymer used in the present invention is:
It is 5 to 30% by weight, preferably 10 to 25% by weight.

If this proportion is less than 5% by weight, the holding power of the linear diblock copolymer obtained will decrease, and if this proportion is less than 30% by weight,
If it exceeds 100%, the initial adhesive strength of the linear diblock copolymer obtained will decrease.

The linear diblock copolymer used in the present invention has a polystyrene equivalent weight average molecular weight of 50.000 to 15
It is 0,000. If the molecular weight is below the above-mentioned lower limit, the holding power of the block copolymer obtained will be insufficient, and if it is above the above-mentioned upper limit, the processability of the obtained block copolymer will be unsatisfactory.

In the block copolymer composition of the present invention, the first component (
The weight ratio of the tri-branched block copolymer) and the second component (linear diblock copolymer) is 5° to 95,150 to 5, preferably 50 to 90,150 to 1O. If it is out of this range, the holding power of the block copolymer composition obtained will decrease, and if the proportion of the tribranched block copolymer exceeds 95% by weight, the processability will be unsatisfactory. Note that up to 5% by weight of the block copolymer composition can be replaced with a block copolymer other than the tri-branched block copolymer and the linear diblock copolymer within a range that does not impair the effects of the present invention.

The block copolymer composition of the present invention can be obtained by separately synthesizing the tri-branched block copolymer and the linear diblock copolymer, and then mixing them in the above weight ratio by any method. can be obtained by Also,
As described later, an A-B block copolymer in which a polymer block B of a conjugated diene monomer having a polymerization active terminal is directly bonded to a polymer block A of an aromatic vinyl monomer is coupled to form a tri-branched copolymer. By controlling the amount of the coupling agent when obtaining a block copolymer, a block copolymer composition consisting of a tribranched block copolymer and a linear diblock copolymer in the above weight ratio can be obtained. can be obtained at once.

The method for synthesizing the tri-branched block copolymer used in the present invention is not particularly limited, but for example, it can be produced according to the following processes (a) to (d). That is, (a) First, an aromatic vinyl monomer is polymerized using a monolithium initiator in a solvent to which a polar compound is added.

As the monolithium initiator, known ones capable of initiating the polymerization of aromatic vinyl monomers and conjugated diene monomers can be used, including methyllithium, n-propyllithium, n-
Typical examples thereof include butyllithium and 5ec-butyllithium, but n-butyllithium is particularly preferred. The amount of monolithium initiator used is calculated according to the desired molecular weight of the polymer in a manner well known to those skilled in the art.

The polymerization solvent is not particularly limited as long as it is inert to the monolithium initiator, and for example, an open chain hydrocarbon solvent, a cyclic hydrocarbon solvent, or a mixed solvent thereof is used. Open-chain hydrocarbon solvents include n-butane, isobutane, or mixtures thereof; l-butene, isobutylene, trans-2-butene, cis-2-butene, or mixtures thereof, l-pentene, trans-2-pentene, Cis-2-pentene or mixtures thereof:
Examples include open chain alkanes and alkenes having 4 to 5 carbon atoms such as n-pentane, isopentane, neo-pentane or mixtures thereof; l-pentene, trans-2-pentene, cis-2-pentene or mixtures thereof. can. Specific examples of the cyclic hydrocarbon solvent include aromatic compounds such as benzene, toluene, and xylene, and alicyclic hydrocarbons such as dichlorohexane. From the point of view 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 and the cyclic hydrocarbon solvent of No. 5 are mixed at a heavy electric ratio.
Range of 5:95 to 50:50, preferably 10:90 to
It is preferable to use a mixed solvent in the range of 40:60.

In addition, although it is not essential to use a polar compound, it can be used to adjust the polymerization initiation rate, adjust the vinyl content of the polymer of conjugated diene monomers, and form blocks of polymers of aromatic vinyl monomers. It is possible to adjust the molecular weight distribution of. As the polar compound, among the known polar compounds used as a vinyl-containing ft adjuster or randomizer in the copolymerization of a conjugated diene monomer or an aromatic vinyl monomer with a monolithium initiator, Aromatic or aliphatic ethers or tertiary amines having a dielectric constant 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; and tertiary monoamines such as trimethylamine, triethylamine, and tripropylamine. One or more of these are used.

In order to obtain a predetermined molecular weight distribution of the polymer block of the aromatic vinyl monomer and to improve the properties of the pressure-sensitive adhesive containing the obtained block copolymer, the preferred amount of the polar compound to be used is as follows: 0.1 per mole of monolithium initiator
-100 mol, more preferably 0.5-20 mol.

In the present invention, the method of polymerizing the aromatic vinyl monomer is not particularly limited, and includes batch polymerization in which the entire amount of the aromatic vinyl monomer and the entire amount of the initiator are charged into a batch polymerization system and reacted, and continuous polymerization. Continuous polymerization in which the reaction is carried out while being supplied to the polymerization system,
Any of the commonly used methods, such as a method in which a portion of the monomer and initiator is used to carry out polymerization to a predetermined conversion rate, and then the remaining monomer and initiator are added to continue polymerization. May be used. Polymerization is usually carried out at 0°C to 90°C, preferably at 2
It is carried out in the range of 0°C to 70°C. If 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 type 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, and polymerization is carried out.

Although it is preferable to add the conjugated diene monomer continuously in order to control the heat of reaction, other methods of addition may be used. In this way, an AB block copolymer is produced in which a polymer block B of a conjugated diene monomer having a polymerization-active terminal is directly bonded to a polymer block A of an aromatic vinyl monomer.

(c) After the completion of the polymerization reaction of the conjugated diene monomer, a coupling agent is added to the polymerization system to bond the A-B block copolymer having the active terminal to form the desired general formula ( I) (A B) 3X (wherein A is a polymer block of aromatic vinyl monomer, B is a polymer block of conjugated diene monomer, and X is silane trifunctional or tetrafunctional) A tri-branched block copolymer represented by (representing the residue of a reactive coupling agent) is obtained. At this time, a compound that promotes the coupling reaction can also be added.

In the present invention, the amount of coupling agent used is important. In order to obtain the tri-branched block copolymer used in the present invention, the amount of the silane coupling agent used is 1/1 of the silane coupling agent per mole of the monolithium initiator used in the polymerization. Optimally, 3 moles are used.

When the amount of the coupling agent is increased, a bi-branched block copolymer ((A-B)2X structure, where ASB and X are the same as above) or a residue of the coupling agent at the terminal However, a large amount of A, B, and X (where A, B, and X are the same as above) are produced as by-products.

It is also possible to obtain a tri-branched block copolymer and a linear diblock copolymer at the same time, and for this purpose, 173
Submolar amounts of trifunctional coupling agents are used. This amount can be determined by calculation according to the composition of the target block copolymer composition, but in practice there are problems such as deactivation of the monolithium initiator or coupling agent, so preliminary experiments are carried out. It is best to find the optimal value by doing the following.

(iv) After the coupling reaction is completed, water, alcohol, acid, etc. are added as necessary to deactivate the polymerization active species, and an anti-aging agent is added, followed by a known polymer separation method (e.g. steam stripping, etc.). ) to separate the polymer, and through a drying process, the desired tribranched block copolymer or a mixture of this and a linear diblock copolymer is obtained.

The linear diblock copolymer used in the present invention is
Synthesis process of the above tri-branched block copolymer (a)
After obtaining a linear C-t block copolymer in which the isoprene polymer block I having a polymerization active terminal was directly bonded to the aromatic vinyl monomer polymer block C in the same manner as in ~(b), the above-mentioned As in process (d), after deactivating the polymerization active species and adding an antiaging agent, it can be obtained through separation and drying steps without performing a coupling reaction.

The adhesive composition of the present invention mainly consists of the block copolymer composition of the present invention and a tackifying resin.

A part of the block copolymer composition used in the pressure-sensitive adhesive composition of the present invention can be replaced with other polymers such as natural rubber, butadiene rubber, and isoprene rubber, as long as the effects of the present invention are not impaired.

As the tackifier resin used in the present invention, conventionally known tackifier resins that are used in adhesives using conventional block copolymers similar to the block copolymer used in the present invention can be used. Specifically, rosin; modified rosins such as disproportionated rosin and trimerized rosin; esterified products of polyhydric alcohols such as glycol, glycerin, and pentaerythritol with rosin or modified rosin; terpene resin; aliphatic rosin; , aromatic, alicyclic, or aliphatic-aromatic copolymerized hydrocarbon resins, or hydrides thereof; phenol resins; coumaron-indene resins, and the like. Particularly preferred tackifier resins are aliphatic or aliphatic-aromatic copolymer hydrocarbon resins that are highly compatible with the block copolymer composition of the present invention. The amount of tackifying resin used is 10 parts by weight per 100 parts by weight of the block copolymer composition.
~150 parts by weight.

A softener (plasticizer), an antioxidant, a heat stabilizer, an ultraviolet absorber, a filler, and other compounding agents can be added to the adhesive composition of the present invention, if necessary.

As the softening agent, conventionally known aromatic, paraffinic or naphthenic extender oils used in adhesives; liquid polymers such as polybutene and polyisobutylene can be used. The amount of softener used is usually 100 parts by weight or less per 100 parts by weight of the block copolymer composition.

As an antioxidant, 2,6-tert-butyl-
Hindered phenol compounds such as p-cresol and di-tert-butyl-4-methylphenol; Thiodicarboxylate esters such as dilaurylthiopropionate; Phosphites such as tris(nonylphenyl)phosphite alone used separately or in combination.

The adhesive composition of the present invention can be used as a solution-type adhesive by dissolving it in n-hexane, cyclohexane, benzene, toluene, etc., as an emulsion-type adhesive by dispersing it in water using an emulsifier, or as a solvent-free adhesive. It can be used as a hot melt adhesive. Particularly suitable are hot melt adhesives.

(Effects of the Invention) Thus, the present invention provides a block copolymer composition for adhesives that has a better balance of initial adhesive strength, holding power, flexibility, processability, and thermal stability compared to the prior art. By combining this with a tackifying resin, an excellent adhesive composition can be obtained.

(Example) Below, the present invention will be described in more detail with reference to Examples. In addition, parts and percentages in Examples, Comparative Examples, and Reference Examples are as follows:
Unless otherwise specified, data are based on weight.

Furthermore, in this example, the molecular weight of the polymer is the weight average molecular weight in terms of polystyrene 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.

Reference Example 1 Using a 502 pressure reactor, 18.75 kg of a mixed solvent of n-butane/cyclohexane = 30/70, 240 mmol of dibutyl ether, and 120 mmol of n-butyl lithium initiator were present, and 1 First, 1.52 kg of styrene was polymerized, followed by 6.48 kg of isoprene.
kg was added, and polymerization was carried out for about 1.5 hours while controlling the reaction temperature by reflux cooling so that the reaction temperature was between 50°C and 60°C. Next, silicon tetrachloride 3 was used as a coupling agent.
8 mmol was added and the coupling reaction was carried out for 2 hours.

Thereafter, 50 methanol was added to the reaction mixture as a polymerization terminator, and 4-methyl-di-tert was added as an antioxidant.
-40g of butylphenol was added and mixed well, and the resulting mixed solution was dropped little by little into warm water heated to 85-95°C to volatilize the solvent.

The obtained polymer was pulverized and dried with hot air at 85° C. to obtain a block copolymer mixture (polymer ①).

The molecular weight of polymer ■ is 290,000, and the molecular weight is 3/300,000.
It contained 95% branched block copolymer and 5% linear diblock copolymer having a molecular weight of 100,000.

Reference Example 2 A polystyrene-polyisoprene linear diblock copolymer (polymer ①) was obtained in the same manner as in Example 1 except that the coupling reaction using silicon tetrachloride was not performed. The molecular weight of Polymer (1) was 10,000.

Reference Example 3 A block copolymer mixture (polymer ①) was obtained in the same manner as in Reference Example 1 except that 38 mmol of phenyltrichlorosilane was used as the coupling agent and 12 mmol of tetramethylethylenediamine was used in combination. The molecular weight of Polymer 0 was 290,000, and contained 95% tri-branched block copolymer with a molecular weight of 300,000 and 5% a linear diblock copolymer with a molecular weight of 100,000.

Reference Example 4 A block copolymer mixture (Polymer ○) was obtained in the same manner as in Reference Example 3, except that the amount of phenyltrichlorosilane was changed to 28 mmol. The molecular weight of polymer ■ is 240,000,
70% tri-branched block copolymer with a molecular weight of 300,000, molecules! It contained 30% linear diblock copolymer of 1.1 million.

Reference Example 5 A block copolymer mixture (Polymer ■) was obtained in the same manner as in Reference Example 1, except that 39 mmol of tin tetrachloride was used as the coupling agent. The molecular weight of polymer (■) is 300,000, and 90% is a tri-branched block copolymer with a molecular weight of 300,000, 5% is a four-branched block copolymer, and 2% is a bi-branched block copolymer with a molecular weight of 200,000. It contained 3% of a linear diblock copolymer with a molecular weight of 100,000.

Reference Example 6 A block copolymer mixture (Polymer ■) was obtained in the same manner as in Reference Example 3, except that the amount of phenyltrichlorosilane was changed to 50 mmol. The molecular weight of polymer 〇 is 225,000, and the tri-branched block copolymer with a molecular weight of 300,000 is 37.
．． 5%, a bibranched block copolymer with a molecular weight of 1.2 million is contained in 50%, and the remainder is a linear diblock copolymer with a molecular weight of 100,000 and a linear block copolymer with an A-B-X structure. there were.

Reference Example 7 A block copolymer mixture (polymer ①) was obtained in the same manner as in Reference Example 3 except that the amount of phenyltrichlorosilane was changed to 12 mmol. The molecular weight of polymer ■ is 160,000,
It contained 30% of a tri-branched block copolymer with a molecular weight of 300,000 and 70% of a linear diblock copolymer with a molecular weight of 10,000.

Reference Example 1 A block copolymer mixture (Polymer ○) was obtained in the same manner as in Reference Example 1, except that 50 mmol of ethylene tribromide was used as the coupling agent. The molecular weight of polymer ■ is 180,000,
83% bi-branched block copolymer with 1.2 million molecules ff
, a linear diblock copolymer with a molecular weight of 100,000 was contained in an amount of 17%.

Reference Example 9 A polystyrene-polyisoprene block copolymer having a polymerization active terminal was obtained in the same manner as in Example 1 except that the amount of the initiator n-butyllithium was 60 mmol and the amount of styrene was 0.76 kg. , and further polystyrene 0.7
After adding 6 kg and continuing polymerization at 60°C for 2 hours, the following operations were performed to stop the polymerization in the same manner as in Example 1, and A-I
A linear triblock copolymer (polymer 〇) having the structure -A (where A and I are the same as above) was obtained. The molecular weight of Polymer ○ was I90,000.

Reference Example 1O A polystyrene-polybutadiene linear diblock copolymer (Polymer@1) was obtained in the same manner as Reference Example 2, except that butadiene was used instead of isoprene.

The molecular weight of the polymer [phase] was 100,000.

Reference Example 11 A tri-branched polymer with a molecular weight of 300,000 and a weight ratio (S/I ratio) of polystyrene blocks and polyisoprene blocks of 5195 was prepared in the same manner as Reference Example 1 except that the amounts of styrene and isoprene were changed. A mixture of 95% block copolymer and 5% linear block copolymer with molecules ff 100,000 (polymer ■), a tri-branched block copolymer with molecules j 1,300,000 each with an S/I ratio of 40/60. A mixture (Polymer@) of 95% and 5% of a linear diblock copolymer of 1.1 million molecules was obtained.

Reference Example 12 The same procedure as Reference Example 2 was carried out except for changing the polymerization amounts of styrene and isoprene, and the SIT ratio was 2/98.40/2, respectively.
60, linear diblock copolymers (polymer 0, @l) each having a molecular weight of 100,000 were obtained.

Reference Example 13 The same procedure as Reference Example 1 was carried out except that the amount of the initiator was changed, and 95% of a tri-branched block copolymer with a molecular weight of 110,000 and 95% of a tri-branched block copolymer with a molecular weight of 3.
50,000 mixture with 5% linear block copolymer (polymer ■), tri-branched block copolymer with molecules of 41,510,000 95
% and a linear block copolymer with a molecular weight of 170,000 5% (Polymer@), a mixture of 95% of a tri-branched block copolymer with a molecular weight of 270,000 and a linear diblock copolymer with a molecular weight of 90,000 5
% (polymer@) was obtained. Note that the S/I ratio of these block copolymers was 19/81.

Reference Example 14 A linear diblock copolymer (polymer) with a molecular weight of 3, 50,000, and 200,000 and an S/I ratio of 19781 was prepared in the same manner as in Reference Example 2 except that the amount of initiator was changed. [Phase], polymer @l) was obtained.

Example 1 100 parts of the block copolymer composition shown in Table 1 was charged into a stirring vane type kneader, and tackifying resin (Finton M
-100, Nippon Zeon M) 100 parts, naphthenic process oil (Shell Flex 371, manufactured by Shell Chemical)
After adding 30 parts and 1 part of an antioxidant (Antage W-400, manufactured by Yoro Kagaku Kogyo ■) and purging the system with nitrogen gas, the mixture was kneaded at 160 to 180°C to prepare an adhesive composition. did. This adhesive composition was coated onto kraft paper to a thickness of 25 μm using a hot melt coater to prepare an adhesive tape, and the initial adhesive strength and holding power of this adhesive tape were measured. Note that the initial adhesive strength was measured using J l5-20
In accordance with 237. That is, at 23°C, the inclination angle is 30
Attach a 10 cm long adhesive tape with the sticky side facing up to the slope of a stainless steel plate, and insert steel balls of 30 different sizes from 3732 inches in diameter to 1 inch from a position 10 cm above the slope at an initial velocity. It is indicated by the size (number) of the largest diameter steel ball that rolls at zero and stops on the adhesive tape.

The holding force was measured in accordance with JIS-20237. In other words, 25mm+ was applied to a stainless steel plate treated in the same manner as above.
Adhesive tape is attached so that an area of 10 mm x is in contact with the adhesive tape, a load of 1 kg is applied at 50°C, and the time required for the adhesive tape to fall off the stainless steel plate is expressed.

In addition, dumbbell-shaped test samples (distance between gauge lines 15 mm, width of the parallel part 31 mm, thickness 2 mm) were prepared from each block copolymer composition in Table 1, and the tensile test was conducted according to JIS- 6301, and the elongation at break was used as an index of flexibility.

Regarding processability, melt viscosity was measured according to the method of JIS-7210 and used as an index thereof.

Furthermore, regarding thermal stability, pellets of the block copolymer composition were placed in a hot air circulating oven under a nitrogen atmosphere.
After being left at 185°C for 2 hours, the composition of the block copolymer composition was examined by gel permeation chromatography, and the weight ratio of the tri-branched radial block copolymer was compared to that before heating. The degree of decrease was measured and used as an indicator.

These results are shown in Table 1.

From the results in Table 1, it can be seen that the effects of the present invention can be achieved even when using block copolymer compositions other than the block copolymer composition consisting of the tri-branched block copolymer and linear diblock copolymer of the present invention. It turns out that you can't get it.

Example 2 Adhesive compositions were prepared from the block copolymer compositions shown in Table 2 in the same manner as in Example 1, and the same tests as in Example 1 were conducted on these compositions.

The results are shown in Table 2.

From the results in Table 2, it can be seen that the effects of the present invention cannot be obtained when the composition of the block copolymer composition is outside the range of the present invention.

Example 3 Adhesive compositions were prepared from the block copolymer compositions shown in Table 3 in the same manner as in Example 1, and the same tests as in Example 1 were conducted on these compositions.

The results are shown in Table 3.

From the results in Table 3, it can be seen that the effects of the present invention cannot be obtained when the weight ratio of polystyrene blocks to polyisoprene blocks deviates from the conditions of the present invention.

/ /'/''' 7/ Example 4 A pressure-sensitive adhesive composition was prepared from the block copolymer composition shown in Table 4 in the same manner as in Example 1, and the same tests as in Example 1 were conducted on these compositions. Ta.

The results are shown in Table 4.

From the results in Table 4, it can be seen that the effects of the present invention cannot be obtained when the molecular weight of the tri-branched block copolymer or linear diblock copolymer deviates from the conditions of the present invention.

Patent applicant: Kuchimoto Zeo/Co., Ltd.

Claims (1)

[Claims] 1. General formula (I) (A-B)_3X (wherein A is a polymer block of an aromatic vinyl monomer, and B is a polymer block of a conjugated diene monomer) , X represents a residue of a silane-based trifunctional or tetrafunctional coupling agent), and the weight ratio of polymer block A to polymer block B is 10.
/90 to 30/70, and 50 to 95% by weight of a tribranched block copolymer of the general formula (II) C-I (wherein, C represents a polymer block of an aromatic vinyl monomer, I represents an isoprene polymer block), and the weight ratio of polymer block C and polymer block I is 5/95 to 30/7.
A block copolymer composition for an adhesive, characterized in that it comprises 50 to 5% by weight of a linear diblock copolymer of 0. 2. Block copolymer composition 100 for adhesives according to claim 1
and 10 to 150 parts by weight of a tackifying resin.