JP5402780B2 - Hot melt adhesive composition - Google Patents

Description

  The present invention relates to a hot-melt adhesive composition, and more specifically, for bonding members constituting paper diapers, sanitary products, and the like, and suitably used as a pressure-sensitive adhesive for pressure-sensitive adhesive labels, etc., at a relatively low temperature. It is related with the hot-melt adhesive composition which is easy to apply, has a long open time, and is excellent in holding power and tackiness.

  Hot melt adhesives solidify in a short time, so that various products can be bonded efficiently, and because no solvent is required, the adhesive is highly safe to the human body. Therefore, it is used in various fields. For example, when manufacturing sanitary goods such as paper diapers and sanitary goods, hot melt adhesives are used in order to bond members constituting them. In addition, hot-melt adhesives are also awarded as pressure-sensitive adhesives used in various pressure-sensitive adhesive tapes and office and industrial labels.

  Various polymers are used as the base polymer for constituting the hot melt adhesive. As the hot melt adhesive used for manufacturing sanitary products, styrene-isoprene-styrene block copolymer (SIS) and styrene- which are excellent in the adhesiveness of polyolefins often used as materials for sanitary products. Hot melt adhesives based on aromatic vinyl-conjugated diene-aromatic vinyl block copolymers such as butadiene-styrene block copolymers (SBS) are often used.

  By the way, the hot melt adhesive used for manufacturing sanitary goods is required to have various performances. Among them, it is easy to apply at a relatively low temperature. Performances such as long open time, excellent holding power and tackiness are strongly required. In order to achieve such required performance, various studies have been made on hot melt adhesives based on an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer.

  For example, Patent Document 1 discloses that a low-temperature adhesive force can be achieved by forming a hot melt adhesive using aromatic vinyl-conjugated diene-aromatic vinyl block copolymers having different molecular weights of two aromatic vinyl blocks. It is disclosed that a hot-melt adhesive having excellent and low viscosity at the time of melting and having high adhesive strength and high tack strength can be obtained. Although the hot melt adhesive described in Patent Document 1 has a low viscosity at 160 ° C., the viscosity rapidly increases at a temperature lower than that, so that coating at a lower temperature is difficult, and There was a problem that the open time after coating was not sufficient.

  In Patent Document 2, an elastomer composition containing a branched aromatic vinyl-isoprene block copolymer, a linear aromatic vinyl-isoprene block copolymer, and polyisoprene is good. It is disclosed that it can be used as a hot melt adhesive having a high holding power and an initial adhesive strength (tackiness) and having a relatively low viscosity at a low temperature. According to the elastomer composition described in Patent Document 2, although the viscosity at a relatively low temperature can be lowered, it cannot be said that the degree of improvement is sufficient, and further improvement is desired. It was.

JP-A-8-283865 JP 2006-274158 A

  An object of the present invention is to provide a hot melt adhesive that is easy to apply at a relatively low temperature, has a long open time, and is excellent in holding power and tackiness.

  As a result of intensive studies to achieve the above object, the present inventors have found that an asymmetric aromatic vinyl-conjugated diene-aromatic vinyl block copolymer in which two aromatic vinyl polymer blocks have different weight average molecular weights, and In addition, an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having a specific configuration different from this is blended at a specific ratio to constitute a block copolymer composition, and an aromatic monomer If a tackifying resin containing a specific amount of body units is blended, the melt viscosity at a relatively low temperature is low, and the rise in melt viscosity accompanying a decrease in temperature is slow, so the open time is long, Furthermore, it discovered that the hot-melt adhesive composition which is excellent in tack property and the retention strength after adhesion | attachment is obtained. The present invention has been completed based on these findings.

  Thus, according to the present invention, a block copolymer composition comprising a block copolymer A represented by the following general formula (A) and a block copolymer B represented by the following general formula (B): , A hot melt adhesive composition comprising a tackifying resin, wherein the weight ratio (A / B) of the block copolymer A and the block copolymer B in the block copolymer composition is A hot melt adhesive composition is provided that is 10/90 to 90/10 and has an aromatic monomer unit content of the tackifying resin of 1 to 70% by weight.

^{Ar1 a -D a -Ar2 a (A} )
(Ar ^b -D ^b ) _n -X (B)

In formula (A) and (B), Ar1 ^a and Ar ^b are each an aromatic vinyl polymer block having a weight average molecular weight of 6,000 to 20,000, Ar @ 2 ^a are aromatic having a weight average molecular weight of 22,000 to 400,000 A vinyl polymer block, D ^a and D ^b are each a conjugated diene polymer block having a vinyl bond content of 1 to 20 mol%, X is a single bond or a residue of a coupling agent, n is an integer of 2 or more.

  In the above hot melt adhesive composition, the block copolymer composition occupies aromatic vinyl monomer units with respect to all monomer units constituting the polymer component in the block copolymer composition. The ratio is preferably 13 to 85% by weight.

  The hot melt adhesive composition preferably further contains a softening agent.

  According to the present invention, it is possible to obtain a hot melt adhesive which is easy to apply at a relatively low temperature, has a long open time, and is excellent in holding power and tackiness.

  The hot melt adhesive composition of the present invention comprises a block copolymer composition composed of at least two block copolymers and a tackifying resin. The block copolymer A, which is one of the two block copolymers constituting the block copolymer composition used in the present invention, has different weight average molecular weights represented by the following general formula (A). It is an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having two aromatic vinyl polymer blocks.

^{Ar1 a -D a -Ar2 a (A} )

The above general formula ^(A), Ar1 ^a is an aromatic vinyl polymer block having a weight average molecular weight of 6,000 to 20,000, Ar @ 2 ^a has a weight average molecular weight of an aromatic vinyl polymer block of 22,000 to 400,000 , ^Da is a conjugated diene polymer block having a vinyl bond content of 1 to 20 mol%.

  The block copolymer B which is the other of the two block copolymers constituting the block copolymer composition used in the present invention is an aromatic vinyl-conjugated represented by the following general formula (B). Diene-aromatic vinyl block copolymer.

(Ar ^b -D ^b ) _n -X (B)

In the above general formula (B), Ar ^b is an aromatic vinyl polymer block having a weight average molecular weight of 6000 to 20000, and D ^b is a conjugated diene polymer block having a vinyl bond content of 1 to 20 mol%. X is a single bond or a residue of a coupling agent, and n is an integer of 2 or more.

The aromatic vinyl polymer blocks (Ar1 ^a , Ar2 ^a , Ar ^b ) of the block copolymer A and the block copolymer B are polymer blocks composed of aromatic vinyl monomer units. The aromatic vinyl monomer used for constituting the aromatic vinyl monomer unit of the aromatic vinyl polymer block is not particularly limited as long as it is an aromatic vinyl compound, but styrene, α-methylstyrene, 2 -Methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 4-bromostyrene, 2-methyl-4,6-dichlorostyrene, 2,4-dibromostyrene, vinyl And naphthalene. Of these, styrene is preferably used. These aromatic vinyl monomers can be used alone or in combination of two or more in each aromatic vinyl polymer block. Further, in each aromatic vinyl polymer block, the same aromatic vinyl monomer may be used, or different aromatic vinyl monomers may be used.

Each of the aromatic vinyl polymer blocks (Ar1 ^a , Ar2 ^a , Ar ^b ) of the block copolymer A and the block copolymer B may contain a monomer unit other than the aromatic vinyl monomer unit. good. Monomers constituting monomer units other than aromatic vinyl monomer units that can be included in the aromatic vinyl polymer block include 1,3-butadiene and isoprene (2-methyl-1,3-butadiene). Examples thereof include conjugated diene monomers such as α, β-unsaturated nitrile monomers, unsaturated carboxylic acid or acid anhydride monomers, unsaturated carboxylic acid ester monomers, and non-conjugated diene monomers. . The content of monomer units other than aromatic vinyl monomer units in each aromatic vinyl polymer block is preferably 20% by weight or less, more preferably 10% by weight or less, and substantially Particularly preferred is 0% by weight.

The conjugated diene polymer block (D ^a , D ^b ) of the block copolymer A and the block copolymer B is a polymer block composed of conjugated diene monomer units. The conjugated diene monomer used for constituting the conjugated diene monomer unit of the conjugated diene polymer block is not particularly limited as long as it is a conjugated diene compound. For example, 1,3-butadiene, isoprene, 2, Examples include 3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Among these, it is preferable to use 1,3-butadiene and / or isoprene, and it is particularly preferable to use isoprene. By constituting the conjugated diene polymer block with isoprene units, the resulting hot melt adhesive composition is excellent in adhesiveness and flexibility. These conjugated diene monomers can be used alone or in combination of two or more in each conjugated diene polymer block. In each conjugated diene polymer block, the same conjugated diene monomer may be used, or different conjugated diene monomers may be used. Furthermore, you may perform hydrogenation reaction with respect to a part of unsaturated bond of each conjugated diene polymer block.

The conjugated diene polymer blocks (D ^a , D ^b ) of the block copolymer A and the block copolymer B may each contain a monomer unit other than the conjugated diene monomer unit. Monomers constituting monomer units other than the conjugated diene monomer unit that can be included in the conjugated diene polymer block include aromatic vinyl monomers such as styrene and α-methylstyrene, α, β-unsaturated monomers. Examples include saturated nitrile monomers, unsaturated carboxylic acid or acid anhydride monomers, unsaturated carboxylic acid ester monomers, and non-conjugated diene monomers. The content of monomer units other than the conjugated diene monomer unit in each conjugated diene polymer block is preferably 20% by weight or less, more preferably 10% by weight or less, and substantially 0% by weight. % Is particularly preferred.

The block copolymer A constituting the block copolymer composition is an aromatic vinyl polymer block (Ar1 ^a ) having a relatively small weight average molecular weight, as represented by the general formula (A), a specific An asymmetric aromatic vinyl having a conjugated diene polymer block having a vinyl bond content (D ^a ) and an aromatic vinyl polymer block having a relatively large weight average molecular weight (Ar 2 ^a ) connected in this order It is a conjugated diene-aromatic vinyl block copolymer. The weight average molecular weight (Mw (Ar1 ^a )) of the aromatic vinyl polymer block (Ar1 ^a ) having a relatively small weight average molecular weight is 6000 to 20000, preferably 7000 to 18000, preferably 8000 to 16000. More preferably. If Mw (Ar1 ^a ) is too small, the resulting hot melt adhesive composition may have low holding power, and if too large, the melt viscosity of the hot melt adhesive composition is extremely high. There is a risk. The weight average molecular weight of the aromatic vinyl polymer block (Ar @ 2 ^a) having a relatively large weight average molecular weight (Mw ^(Ar2 a)) is 22,000 to 400,000, preferably from 25000 to 370000, 30,000 to More preferably, it is 350,000. When Mw (Ar2 ^a) is too small, hot melt adhesive composition obtained, the holding force is low, relatively may become as high melt viscosity at low temperature, Mw (Ar2 ^a) is The block copolymer A that is too large may be difficult to produce.

  In the present invention, the weight average molecular weight of the polymer or polymer block is determined as a value in terms of polystyrene as measured by high performance liquid chromatography.

In the block copolymer A, the weight average molecular weight (Mw (Ar2 ^a )) of the aromatic vinyl polymer block (Ar2 ^a ) having a relatively large weight average molecular weight and the aromatic vinyl weight having a relatively small weight average molecular weight. the ratio of the weight average molecular weight of polymer block ^{(Ar1 a) (Mw (Ar1} a)) (Mw (Ar2 a) / Mw (Ar1 a)) is not particularly limited but is usually from 1.5 to 67, 2 It is preferable that it is -40, and it is more preferable that it is 3-35. By constituting the block copolymer A in this way, the resulting hot melt adhesive composition has a relatively low melt viscosity at a low temperature, and has a long open time and excellent coating properties. It becomes.

The vinyl bond content of the conjugated diene polymer block (D ^a ) of the block copolymer A (the ratio of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units) is 1 It is -20 mol%, it is preferable that it is 2-15 mol%, and it is more preferable that it is 3-10 mol%. If the vinyl bond content is too high, the resulting hot melt adhesive composition may be too hard, resulting in poor adhesion.

The weight average molecular weight (Mw (D ^a )) of the conjugated diene polymer block (D ^a ) of the block copolymer A is not particularly limited, but is usually 20000 to 200000, preferably 30000 to 150,000, preferably 35000. More preferably, it is ˜100,000.

  The content of the aromatic vinyl monomer unit relative to all the monomer units of the block copolymer A is not particularly limited, but is preferably 35% by weight or more, more preferably 41% by weight or more, More preferably, it is 45-87 weight%, Most preferably, it is 50-85 weight%. By setting the content of the aromatic vinyl monomer unit with respect to all the monomer units of the block copolymer A within this range, the obtained hot-melt adhesive composition has excellent holding power.

  Although the weight average molecular weight as the whole block copolymer A is not specifically limited, Usually, it is 70000-500000, It is preferable that it is 80000-470000, and it is more preferable that it is 90000-450,000.

The block copolymer B constituting the block copolymer composition used in the present invention is an aromatic vinyl polymer block (Ar ^b ) having a specific weight average molecular weight as represented by the general formula (B). Two or more diblock bodies (Ar ^b -D ^b ) formed by bonding a conjugated diene polymer block (D ^b ) having a specific vinyl bond content with a direct single bond or the remaining coupling agent It is a block copolymer constituted by bonding through a group. The weight average molecular weight (Mw (Ar ^b )) of the aromatic vinyl polymer block (Ar ^b ) constituting the block copolymer B is 6000 to 20000, preferably 7000 to 18000, preferably 8000 to 16000. More preferably. If Mw (Ar ^b ) is too small, the resulting hot melt adhesive composition may have low holding power, and if too large, the melt viscosity of the hot melt adhesive composition is extremely high. There is a risk. The weight average molecular weights (Mw (Ar ^b )) of the aromatic vinyl polymer blocks that the block copolymer B has may be equal or different from each other as long as they are within the above range. Good, but preferably substantially equal. Moreover, the weight average molecular weight (Mw (Ar ^b )) of these aromatic vinyl polymer blocks is the weight average of the aromatic vinyl polymer block (Ar 1 ^a ) having a relatively small weight average molecular weight of the block copolymer A. molecular weight (Mw ^(Ar1 a)), and more preferably substantially equal.

The vinyl bond content of the conjugated diene polymer block (D ^b ) of the block copolymer B is 1 to 20 mol%, preferably 2 to 15 mol%, and preferably 3 to 10 mol%. More preferred. If the vinyl bond content is too high, the resulting hot melt adhesive composition may be too hard, resulting in poor adhesion. The vinyl bond content of the conjugated diene polymer block (D ^b ) of the block copolymer B is substantially equal to the vinyl bond content of the conjugated diene polymer block (D ^a ) of the block copolymer A. Is preferred.

The block copolymer B, aromatic vinyl polymer block (Ar ^b) a conjugated diene polymer block ^{(D b)} and formed by bonding diblock body ^{(Ar b} -D b) is a direct single bond, Alternatively, they are bonded via a residue of a coupling agent. In addition, what is mentioned later is mentioned as an example of the coupling agent which comprises the residue of a coupling agent. The number of diblock bodies (Ar ^b -D ^b ) to be bonded (that is, n in the general formula (B)) is not particularly limited as long as it is 2 or more, and a block copolymer in which diblock bodies are bonded in different numbers. B may be mixed. Although n in general formula (B) will not be specifically limited if it is an integer greater than or equal to 2, Usually, it is an integer of 2-8, Preferably it is an integer of 2-4.

The weight average molecular weight (Mw (D ^b )) of the conjugated diene polymer block (D ^b ) of the block copolymer B is not particularly limited, but is usually 20000 to 200000, preferably 30000 to 150,000, preferably 35000. More preferably, it is ˜100,000. The weight average molecular weight (Mw (D ^b )) of the conjugated diene polymer block (D ^b ) of the block copolymer B is the weight average molecular weight of the conjugated diene polymer block (D ^a ) of the block copolymer A ( Mw (D ^a )) is preferably substantially equal. In addition, when using the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer manufactured without using a coupling agent as the block copolymer B, the conjugated diene polymer block contained in it is all single quantities. The body unit is directly bonded, and cannot be said to be actually composed of two conjugated diene polymer blocks (D ^b ). However, in the present invention, even such a conjugated diene polymer block is conceptually one in which two conjugated diene polymer blocks (D ^b ) having substantially the same weight average molecular weight are bonded by a single bond. As such, it shall be handled. Therefore, for example, in the block copolymer B which is an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer produced without using a coupling agent, the weight average molecular weight of the conjugated diene polymer block as a whole is 100,000. , The Mw (D ^b ) shall be handled as being 50000.

  The content of the aromatic vinyl monomer unit with respect to all the monomer units of the block copolymer B is not particularly limited, but is usually 10 to 35% by weight, preferably 12 to 32% by weight, More preferably, it is -30 wt%. Moreover, the weight average molecular weight as the whole block copolymer B is not specifically limited, However, Usually, it is 50000-400000, It is preferable 60000-350,000, It is more preferable that it is 70000-300000.

  Ratio of weight average molecular weight (Mw) and number average molecular weight (Mn) of each polymer block constituting block copolymer A and block copolymer B constituting the block copolymer composition used in the present invention (Mw) The molecular weight distribution represented by / Mn) is not particularly limited, but is usually 1.1 or less, preferably 1.05 or less.

  The weight ratio (A / B) of the block copolymer A and the block copolymer B contained in the block copolymer composition used in the present invention is 10/90 to 90/10, and 25/75 to 85/15 is preferable, and 36/64 to 80/20 is more preferable. By containing each block copolymer at such a ratio, the resulting hot melt adhesive composition has excellent coating properties with a relatively low melt viscosity at a low temperature, and adhesion. Later holding power becomes high. On the other hand, if this ratio is too small, the melt viscosity at low temperatures may increase, and if this ratio is too large, the holding power may be inferior.

  The block copolymer composition used in the present invention may contain only the block copolymer A and the block copolymer B as polymer components, but other than the block copolymer A and the block copolymer B. It may contain a polymer component. Examples of the polymer component other than the block copolymer A and the block copolymer B that can be included in the block copolymer composition used in the present invention include aromatic vinyl other than the block copolymer A and the block copolymer B. Conjugated diene-aromatic vinyl block copolymer, aromatic vinyl-conjugated diene block copolymer, aromatic vinyl homopolymer, conjugated diene homopolymer, aromatic vinyl-conjugated diene random copolymer, and branches thereof Type polymers or thermoplastic elastomers such as polyurethane thermoplastic elastomer, polyamide thermoplastic elastomer, polyester thermoplastic elastomer, polyethylene, polypropylene, polyvinyl chloride, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer Coalescence, polyphenylene ether And thermoplastic resins such as Le, and the like. However, a tackifier resin and a softening agent, which will be described later, are distinguished from the polymer components constituting the block copolymer composition. In the block copolymer composition used in the present invention, the content of the polymer component other than the block copolymer A and the block copolymer B is preferably 20% by weight or less based on the entire polymer component. More preferably, it is 10% by weight or less.

  In the block copolymer composition used in the present invention, the ratio of the aromatic vinyl monomer unit to the total monomer units constituting the polymer component in the block copolymer composition (in the following description, the whole It is possible to adjust the balance between the adhesive strength and the retention strength of the resulting hot-melt adhesive composition by adjusting the aromatic vinyl monomer unit content). The total aromatic vinyl monomer unit content is not particularly limited, but is preferably 13 to 85% by weight, more preferably 18 to 70% by weight, and 20 to 60% by weight. % Is more preferable. If the total aromatic vinyl monomer unit content is too small, the resulting hot melt adhesive composition may be poor in holding power, and the total aromatic vinyl monomer unit content is If it is too large, the resulting hot melt adhesive composition will be too hard and the adhesive strength may be poor. The total aromatic vinyl monomer unit content is determined by the block copolymer A, the block copolymer B and the other polymer components constituting the block copolymer composition, and the respective aromatic vinyl monomers. It can be easily adjusted by taking into account the content of the units and adjusting their blending amount. In the case where all the polymer components constituting the block copolymer composition are composed only of aromatic vinyl monomer units and conjugated diene monomer units, Rubber Chem. Technol. , 45, 1295 (1972), ozonolysis of the polymer component of the block copolymer composition, followed by reduction with lithium aluminum hydride, decomposes the conjugated diene monomer unit portion, Since only the aromatic vinyl monomer unit portion can be taken out, the entire aromatic vinyl monomer unit content can be easily measured.

  Although the weight average molecular weight of the whole polymer component which comprises the block copolymer composition used by this invention is not specifically limited, Usually, it is 50000-500000, It is preferable 60000-450,000, It is 70000-400000 Is more preferable. Further, the molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the entire polymer components constituting the block copolymer composition used in the present invention is particularly limited. Although it is not carried out, it is 1.01-10 normally, it is preferable that it is 1.03-5, and it is more preferable that it is 1.05-3.

  Further, the melt index of the block copolymer composition used in the present invention is not particularly limited, but is usually 1 to 70 g / in as a value measured in accordance with ASTM D-1238 (G condition, 200 ° C., 5 kg). 10 minutes, preferably 2 to 65 g / 10 minutes, and more preferably 3 to 60 g / 10 minutes.

  The method for obtaining the block copolymer composition used in the present invention is not particularly limited. For example, according to the conventional block copolymer production method, block copolymer A and block copolymer B are produced separately, and if necessary, after blending other polymer components and the like, It can manufacture by mixing according to conventional methods, such as kneading | mixing and solution mixing. However, from the viewpoint of obtaining a block copolymer composition having a particularly desirable configuration with higher productivity, the following production method is preferred.

  That is, the block copolymer composition used in the present invention is preferably produced using a production method comprising the following steps (1) to (5).

(1): Step of polymerizing an aromatic vinyl monomer using a polymerization initiator in a solvent (2): A solution containing an aromatic vinyl polymer having an active terminal obtained in the step (1) above Step (3) of adding a conjugated diene monomer to the solution containing an aromatic vinyl-conjugated diene block copolymer having an active end obtained in the step (2) above with respect to the active end Step (4) of adding a coupling agent to form a block copolymer B in such an amount that the functional group is less than 1 molar equivalent: The aromatic vinyl monomer is added to the solution obtained in the step (3). Step 5 for forming block copolymer A: step for recovering the block copolymer composition from the solution obtained in step (4) above

  In the above method for producing a block copolymer composition, first, an aromatic vinyl monomer is polymerized using a polymerization initiator in a solvent. The polymerization initiator used is generally an organic alkali metal compound, an organic alkaline earth metal compound known to have anionic polymerization activity for an aromatic vinyl monomer and a conjugated diene monomer, Organic lanthanoid series rare earth metal compounds and the like can be used. As the organic alkali metal compound, an organic lithium compound having one or more lithium atoms in the molecule is particularly preferably used. Specific examples thereof include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, Organic monolithium compounds such as sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, stilbenelithium, dialkylaminolithium, diphenylaminolithium, ditrimethylsilylaminolithium, methylenedilithium, tetramethylenedilithium, hexamethylene Organic dilithium compounds such as dilithium, isoprenyl dilithium and 1,4-dilithio-ethylcyclohexane, and further organic trilithium compounds such as 1,3,5-trilithiobenzene It is. Among these, an organic monolithium compound is particularly preferably used.

  Examples of the organic alkaline earth metal compound used as a polymerization initiator include n-butyl magnesium bromide, n-hexyl magnesium bromide, ethoxy calcium, calcium stearate, t-butoxystrontium, ethoxy barium, isopropoxy barium, ethyl mercapto barium, Examples thereof include t-butoxybarium, phenoxybarium, diethylaminobarium, barium stearate, and ethylbarium. Specific examples of other polymerization initiators include lanthanoid series rare earth metal compounds containing neodymium, samarium, gadolinium, etc./alkylaluminum/alkylaluminum halides / alkylaluminum hydrides, titanium, vanadium, samarium, gadolinium. Examples thereof include those having a uniform system in an organic solvent such as a metallocene-type catalyst containing a living polymer and the like and having living polymerizability. In addition, these polymerization initiators may be used individually by 1 type, and may mix and use 2 or more types.

  The amount of the polymerization initiator used may be determined according to the molecular weight of each target block copolymer, and is not particularly limited, but is usually 0.01 to 20 mmol, preferably 100 g per 100 g of all monomers used. Is from 0.05 to 15 mmol, more preferably from 0.1 to 10 mmol.

  The solvent used for the polymerization is not particularly limited as long as it is inert to the polymerization initiator. For example, a chain hydrocarbon solvent, a cyclic hydrocarbon solvent, or a mixed solvent thereof is used. Chain hydrocarbon solvents include n-butane, isobutane, 1-butene, isobutylene, trans-2-butene, cis-2-butene, 1-pentene, trans-2-pentene, cis-2-pentene and n-pentane C 4-6 linear alkanes and alkenes such as, isopentane, neo-pentane, n-hexane and the like can be exemplified. Specific examples of the cyclic hydrocarbon solvent include aromatic compounds such as benzene, toluene and xylene; alicyclic hydrocarbon compounds such as cyclopentane and cyclohexane. These solvents may be used alone or in combination of two or more.

  The amount of the solvent used for the polymerization is not particularly limited, but the concentration of the entire block copolymer in the solution after the polymerization reaction is usually 5 to 60% by weight, preferably 10 to 55% by weight, more preferably 20 to 50%. Set the weight%.

  In obtaining a block copolymer composition, a Lewis base compound may be added to a reactor used for polymerization in order to control the structure of each polymer block of each block copolymer. Examples of the Lewis base compound include ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether and diethylene glycol dibutyl ether; tetramethylethylenediamine, trimethylamine, triethylamine, pyridine, quinuclidine and the like. Tertiary amines; alkali metal alkoxides such as potassium-t-amyl oxide and potassium-t-butyl oxide; phosphines such as triphenylphosphine; and the like. These Lewis base compounds are used alone or in combination of two or more, and are appropriately selected within a range not impairing the object of the present invention.

  Further, the timing of adding the Lewis base compound during the polymerization reaction is not particularly limited, and may be appropriately determined according to the structure of each target block copolymer. For example, it may be added in advance before the polymerization is started, or may be added after polymerizing a part of the polymer block. You may add further, after superposing | polymerizing a polymer block.

  The polymerization reaction temperature is usually 10 to 150 ° C, preferably 30 to 130 ° C, more preferably 40 to 90 ° C. The time required for the polymerization varies depending on the conditions, but is usually within 48 hours, preferably 0.5 to 10 hours. The polymerization pressure is not particularly limited as long as it is carried out within a range of pressure sufficient to maintain the monomer and solvent in the liquid phase within the above polymerization temperature range.

Under the conditions as described above, a solution containing an aromatic vinyl polymer having an active terminal can be obtained by polymerizing an aromatic vinyl monomer using a polymerization initiator in a solvent. The aromatic vinyl polymer having an active end is composed of an aromatic vinyl polymer block (Ar1 ^a ) having a relatively small weight average molecular weight of the block copolymer A and a block copolymer. The aromatic vinyl polymer block (Ar ^b ) of the combined B will be constituted. Therefore, the amount of the aromatic vinyl monomer used at this time is determined according to the target weight average molecular weight of these polymer blocks.

The next step is a step of adding a conjugated diene monomer to a solution containing an aromatic vinyl polymer having an active end obtained as described above. By adding this conjugated diene monomer, a conjugated diene polymer chain is formed from the active end, and a solution containing an aromatic vinyl-conjugated diene block copolymer (diblock) having an active end is obtained. The amount of the conjugated diene monomer used here is determined so that the resulting conjugated diene polymer chain has the weight average molecular weight of the conjugated diene polymer block (D ^b ) of the target block copolymer B. .

  In the next step, in the solution containing the aromatic vinyl-conjugated diene block copolymer having an active terminal (diblock) obtained as described above, the functional group is less than 1 molar equivalent with respect to the active terminal. Add the coupling agent in such an amount.

  The coupling agent to be added is not particularly limited, and any bifunctional or higher functional coupling agent can be used. Examples of the bifunctional coupling agent include bifunctional halogenated silanes such as dichlorosilane, monomethyldichlorosilane, and dimethyldichlorosilane; bifunctional alkoxysilanes such as diphenyldimethoxysilane and diphenyldiethoxysilane; dichloroethane and dibromoethane. Difunctional tin halides such as dichlorotin, monomethyldichlorotin, dimethyldichlorotin, monoethyldichlorotin, diethyldichlorotin, monobutyldichlorotin, dibutyldichlorotin, etc. Dibromobenzene, benzoic acid, CO, 2-chloropropene and the like. Examples of the trifunctional coupling agent include trifunctional halogenated alkanes such as trichloroethane and trichloropropane; trifunctional halogenated silanes such as methyltrichlorosilane and ethyltrichlorosilane; methyltrimethoxysilane, phenyltrimethoxysilane, And trifunctional alkoxysilanes such as phenyltriethoxysilane; Examples of the tetrafunctional coupling agent include tetrafunctional halogenated alkanes such as carbon tetrachloride, carbon tetrabromide, and tetrachloroethane; tetrafunctional halogenated silanes such as tetrachlorosilane and tetrabromosilane; tetramethoxysilane, Tetrafunctional alkoxysilanes such as tetraethoxysilane; tetrafunctional tin halides such as tetrachlorotin and tetrabromotin; and the like. Examples of the pentafunctional or higher functional coupling agent include 1,1,1,2,2-pentachloroethane, perchloroethane, pentachlorobenzene, perchlorobenzene, octabromodiphenyl ether, decabromodiphenyl ether, and the like. These coupling agents may be used alone or in combination of two or more.

  The amount of the coupling agent added is determined according to the ratio of the block copolymer A and the block copolymer B constituting the block copolymer composition, and is a coupling agent with respect to the active terminal of the polymer. Is not particularly limited as long as the amount of the functional group is less than 1 molar equivalent, but is usually in the range where the functional group of the coupling agent is 0.10 to 0.90 molar equivalent with respect to the active terminal of the polymer. , 0.15 to 0.70 molar equivalent is preferable.

  As described above, in a solution containing an aromatic vinyl-conjugated diene block copolymer having an active end (diblock body), a functional group (a functional group capable of reacting with the active end of the polymer) with respect to the active end ) Is less than 1 molar equivalent, and when a coupling agent is added, in some of the aromatic vinyl-conjugated diene block copolymers (diblock bodies) having active ends, The polymer blocks are bonded to each other through a residue of the coupling agent, and as a result, a block copolymer B of the block copolymer composition is formed. And the remaining part of the aromatic vinyl-conjugated diene block copolymer (diblock body) which has an active terminal will remain in a solution with unreacted.

In the next step, an aromatic vinyl monomer is added to the solution obtained as described above. When an aromatic vinyl monomer is added to the solution, the aromatic vinyl polymer from the end of the aromatic vinyl-conjugated diene block copolymer (diblock body) having an active terminal remaining without reacting with the coupling agent. A chain is formed. This aromatic vinyl polymer chain constitutes an aromatic vinyl polymer block (Ar2 ^a ) having a relatively large weight average molecular weight of the block copolymer A constituting the block copolymer composition. It is. Therefore, the amount of the aromatic vinyl monomer used at this time is determined in accordance with the target weight average molecular weight of the aromatic vinyl polymer block (Ar2 ^a ). By the step of adding the aromatic vinyl monomer, an asymmetric aromatic vinyl-conjugated diene-aromatic vinyl block copolymer constituting the block copolymer A is formed. As a result, the block copolymer is formed. A solution containing the polymer A and the block copolymer B is obtained. In addition, before the step of adding the aromatic vinyl monomer, a solution containing an aromatic vinyl-conjugated diene block copolymer (diblock body) having an active terminal that has not reacted with the coupling agent is conjugated. A diene monomer may be added. When the conjugated diene monomer is added in this way, the weight average molecular weight of the conjugated diene polymer block (D ^a ) of the block copolymer A can be increased as compared with the case where the conjugated diene monomer is not added. In addition, a polymerization terminator (water, methanol, etc.) is added to the solution containing the aromatic vinyl-conjugated diene block copolymer having an active end that has not reacted with the coupling agent in an amount less than the equivalent of the active end. Also good. When the polymerization terminator is added in this manner, the active terminal of the aromatic vinyl-conjugated diene block copolymer (diblock body) is deactivated, and the resulting aromatic vinyl-conjugated diene block copolymer (diblock) is obtained. Body) will be contained in the block copolymer composition.

  In the next step, the target block copolymer composition is recovered from the solution containing the block copolymer A and the block copolymer B obtained as described above. The recovery method may be any conventional method and is not particularly limited. For example, after completion of the reaction, if necessary, a polymerization terminator such as water, methanol, ethanol, propanol, hydrochloric acid, citric acid is added, and if necessary, an additive such as an antioxidant is added. The solution can be recovered by directly applying a known method such as a drying method or steam stripping to the solution. When the block copolymer composition is recovered as a slurry by applying steam stripping or the like, it is dewatered using an arbitrary dehydrator such as an extruder-type squeezer, and a crumb having a moisture content of a predetermined value or less. In addition, the crumb may be dried using any dryer such as a band dryer or an expansion extrusion dryer. The block copolymer composition obtained as described above may be processed into a pellet shape or the like according to a conventional method, and then used for production of a hot melt adhesive composition.

  According to the above production method, since the block copolymer A and the block copolymer B can be obtained continuously in the same reaction vessel, when each block copolymer is produced and mixed individually, In comparison, the target block copolymer composition can be obtained with extremely excellent productivity. Moreover, the obtained block copolymer composition has a particularly desirable balance for obtaining the hot melt adhesive composition of the present invention in which the weight average molecular weight of each polymer block of each block copolymer is obtained. Therefore, it is possible to obtain a hot-melt adhesive composition that is particularly excellent in coating properties and that is excellent in the balance between holding power and adhesive strength.

  The hot melt adhesive composition of the present invention comprises the above block copolymer composition and a tackifier resin having an aromatic monomer unit content of 1 to 70% by weight. is there. The hot melt adhesive composition of the present invention is excellent in coatability at a relatively low temperature, particularly when such a tackifying resin is used in combination with the above block copolymer composition. And it becomes a hot-melt adhesive composition which is also excellent in holding power. The tackifier resin used in the present invention is not particularly limited as long as the aromatic monomer unit content is 1 to 70% by weight, but a hydrocarbon monomer mixture containing an aromatic monoolefin is polymerized. The hydrocarbon resin obtained and the hydride thereof are particularly preferably used.

  Specific examples of the aromatic monoolefin contained in the hydrocarbon monomer mixture used to obtain this hydrocarbon resin include styrene, α-methylstyrene, isopropenyltoluene, vinyltoluene, and indene. Of these, styrene is particularly preferably used. The hydrocarbon monomer mixture preferably contains an aliphatic monoolefin having 4 to 8 carbon atoms and an aliphatic diolefin having 4 to 5 carbon atoms as components other than the aromatic monoolefin. Specific examples of the aliphatic monoolefin having 4 to 8 carbon atoms include chain monoolefins such as butenes, pentenes, methylbutenes, methylpentenes and diisobutylenes, and cyclic such as cyclopentene, cyclohexene and methylcyclopentenes. A monoolefin is mentioned. Specific examples of the aliphatic diolefin having 4 to 5 carbon atoms include chain diolefins such as 1,3-butadiene, isoprene and 1,3-pentadiene, and cyclic diolefins such as cyclopentadiene.

  Such a hydrocarbon monomer mixture can generally be obtained as a naphtha cracking fraction at -20 to 60 ° C., and an aliphatic monoolefin fraction and / or an aromatic monoolefin fraction is added to this fraction. These may be used as a hydrocarbon monomer mixture. The polymerization method of the hydrocarbon monomer mixture is not particularly limited, but the polymerization is usually performed using an acidic metal halide catalyst such as aluminum chloride.

  The aromatic monomer unit content of the tackifying resin used in the present invention is not particularly limited as long as it is in the range of 1 to 70% by weight, but is preferably in the range of 2 to 60% by weight, and 5 to 50%. It is particularly preferred that it is in the range of wt%.

  In the hot melt adhesive composition of the present invention, a so-called non-aromatic tackifier resin having an aromatic monomer unit content of less than 1% by weight can be used in combination as a tackifier resin. It is. Specific examples of this non-aromatic tackifier resin include rosin tackifier resins, terpene tackifier resins, aliphatic tackifier resins, alicyclic tackifier resins, and hydrides thereof. . In addition, when using together non-aromatic type tackifying resin, what is necessary is just to make the aromatic monomer unit content as the whole tackifying resin into the above-mentioned range.

  Although the weight average molecular weight of the tackifier resin used by this invention is not specifically limited, Usually, it is the range of 300-6000, Preferably, it is the range of 500-5000. The softening point of the tackifying resin is not particularly limited, but is usually in the range of 50 to 160 ° C, and preferably in the range of 60 to 120 ° C.

  Although the usage-amount of tackifying resin in the hot melt adhesive composition of this invention is not specifically limited, It is 50-400 weight part normally per 100 weight part of block copolymer compositions, Preferably it is 60-350. Parts by weight, more preferably 70 to 300 parts by weight.

  The hot melt adhesive composition of the present invention preferably further contains a softening agent. Conventionally known softeners can be used as the softener. Specifically, aromatic, paraffinic or naphthenic extender oil (extender oil) usually added to hot melt adhesive compositions; liquid polymers such as polybutene and polyisobutylene should be used. Can do. The amount of the softener used is not particularly limited, but it is 500 parts by weight or less, preferably 10 to 350 parts by weight, more preferably 30 to 250 parts by weight, per 100 parts by weight of the block copolymer composition. . In addition, a softener may be used individually by 1 type and may be used in combination of 2 or more type.

  An antioxidant may be added to the hot melt adhesive composition of the present invention as necessary. The kind is not specifically limited, For example, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,6-di-t-butyl-p-cresol, di Hindered phenolic compounds such as t-butyl-4-methylphenol; thiodicarboxylate esters such as dilauryl thiopropionate; phosphites such as tris (nonylphenyl) phosphite; it can. Although the usage-amount of antioxidant is not specifically limited, It is 10 weight part or less normally with respect to 100 weight part of block copolymer compositions, Preferably it is 0.5-5 weight part. In addition, an antioxidant may be used individually by 1 type and may be used in combination of 2 or more type.

  Moreover, other compounding agents, such as a heat stabilizer, a ultraviolet absorber, and a filler, can be further added to the hot melt adhesive composition of the present invention. The hot melt adhesive composition of the present invention is preferably a solvent-free composition that does not contain a solvent.

  In obtaining the hot melt adhesive composition of the present invention, the method of mixing the block copolymer composition with the tackifier resin and various additives is not particularly limited. For example, the components are uniformly dissolved in a solvent. And a method of 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.

  In using the hot melt adhesive of the present invention, the application method to various members is not particularly limited. For example, the application can be performed by techniques such as T-die coating, roll coating, multi-bead coating, spray coating, foam coating, and the like. Can be done.

  The hot melt adhesive composition of the present invention is easy to apply at a relatively low temperature, has a long open time, and is excellent in holding power and tackiness. Therefore, the hot-melt adhesive composition of the present invention can be easily applied to the bonding of various members, and can perform energy-saving, high productivity and high holding power. . Furthermore, the hot melt adhesive composition of the present invention has a high shear fracture temperature and is excellent in adhesive strength at high temperatures.

  The hot melt adhesive composition of the present invention can be applied to various uses, and the use is not limited, but the coating property at a relatively low temperature is good. Therefore, it is suitably used for hot-melt bonding of members that may be burned or deteriorated at high temperatures. Especially in the manufacture of disposable diapers and sanitary napkins, the bonding of thermoplastic resin sheets and non-woven fabrics that are their constituent members Can be suitably used. Furthermore, the hot melt adhesive composition of the present invention is excellent in holding power and tackiness, and has relatively good coatability at a low temperature. Therefore, it can be used as an adhesive for various adhesive tapes and labels. Adhesive tapes and labels that are suitably used, energy saving, high productivity, and excellent holding power and tackiness can be provided.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In addition, unless otherwise indicated, the part and% in each example are a basis of weight.

  Various measurements were performed according to the following methods.

[Weight average molecular weight of block copolymer and block copolymer composition]
Molecular weight in terms of polystyrene was determined by high performance liquid chromatography using tetrahydrofuran as a carrier at a flow rate of 0.35 ml / min. The apparatus is an HLC8220 manufactured by Tosoh Corporation, the column is a combination of three Shodex KF-404HQ manufactured by Showa Denko (column temperature 40 ° C.), the detector is a differential refractometer and an ultraviolet detector, and the molecular weight is calibrated by a polymer laboratory. The test was carried out using 12 standard polystyrenes (500 to 3 million).

[Weight ratio of each block copolymer in the block copolymer]
It calculated | required from the area ratio of the peak corresponding to each block copolymer of the chart obtained by said high performance liquid chromatography.

[Weight average molecular weight of styrene polymer block]
Rubber Chem. Technol. 45, 1295 (1972), the block copolymer was reacted with ozone and reduced with lithium aluminum hydride to decompose the isoprene polymer block of the block copolymer. Specifically, the procedure was as follows. That is, 300 mg of the sample was dissolved in a reaction vessel containing 100 ml of dichloromethane treated with molecular sieves. After putting this reaction container into a cooling tank and making it -25 degreeC, the ozone generated with the ozone generator was introduce | transduced, supplying oxygen at the flow volume of 170 ml / min to the reaction container. After 30 minutes from the start of the reaction, it was confirmed that the reaction was completed by introducing a gas flowing out of the reaction vessel into the potassium iodide aqueous solution. Next, 50 ml of diethyl ether and 470 mg of lithium aluminum hydride were charged into another reaction vessel purged with nitrogen, and the solution reacted with ozone was slowly added dropwise to the reaction vessel while cooling the reaction vessel with ice water. Then, the reaction vessel was placed in a water bath, gradually heated, and refluxed at 40 ° C. for 30 minutes. Thereafter, dilute hydrochloric acid was added dropwise to the reaction vessel little by little while stirring the solution, and the addition was continued until almost no generation of hydrogen was observed. After this reaction, the solid product formed in the solution was filtered off, and the solid product was extracted with 100 ml of diethyl ether for 10 minutes. The extract and the filtrate obtained by filtration were combined and the solvent was distilled off to obtain a solid sample. For the sample thus obtained, the weight average molecular weight was measured according to the above-described method for measuring the weight average molecular weight, and the value was taken as the weight average molecular weight of the styrene polymer block.

[Weight average molecular weight of isoprene polymer block]
Subtract the weight average molecular weight of the corresponding styrene polymer block from the weight average molecular weight of the block copolymer obtained as described above, and obtain the weight average molecular weight of the isoprene polymer block based on the calculated value. It was.

[Styrene unit content of block copolymer]
It calculated | required based on the detection intensity ratio of a differential refractometer and an ultraviolet detector in the measurement of said high performance liquid chromatography. In addition, the copolymer which has different styrene unit content was prepared previously, and the analytical curve was created using them.

[Styrene unit content of block copolymer composition]
It calculated | required based on the measurement of proton NMR.

[Vinyl bond content of isoprene polymer block]
It calculated | required based on the measurement of proton NMR.

[Melt index of block copolymer composition]
The measurement was made according to ASTM D-1238 (G condition, 200 ° C., 5 kg).

[Aromatic monomer unit content of tackifying resin]
It calculated | required based on the measurement of proton NMR.

[Weight average molecular weight of tackifying resin]
The standard polystyrene conversion value was obtained by high performance liquid chromatography using tetrahydrofuran as a carrier at a flow rate of 1.5 ml / min. As the column, Tosoh TSKgel H type G4000XL, G3000XL, G2000XL (column temperature 40 ° C.) was used.

[Softening point of tackifying resin]
According to JIS K2531, it measured by the ring and ball method.

[Tackiness of hot melt adhesive composition]
Loop tack was measured according to FINAT-1991 FTM-9 (Quick-stick tack measurement) to evaluate tackiness. The larger the value, the better the tackiness.

[Adhesive strength of hot melt adhesive composition]
Peel adhesion strength (N / m) at room temperature is measured according to PSTC-1 (180 ° peel adhesion test by the US adhesive tape committee) using a hard polyethylene plate as an adherend at 23 ° C. Thus, the adhesive strength was evaluated. The larger the value, the better the adhesion.

[Holding power of hot melt adhesive composition]
The sample is an adhesive tape having a width of 10 mm, hard polyethylene is used as the adherend, and the adhesive part is 10 × 25 mm and the load is 3.92 according to PSTC-6 (retention force test method by the US Adhesive Tape Committee). The holding power was evaluated by the time (minutes) until peeling at × 10 ⁴ Pa and a temperature of 40 ° C. The larger the value, the better the holding power.

[Shear fracture temperature (SAFT) of hot melt adhesive composition]
Stainless steel was used as the adherend, and the shear fracture temperature (SAFT) was measured at an adhesive part of 10 × 25 mm, a load of 3.92 × 10 ⁴ Pa, and a temperature increase rate of 0.5 ° C./min. The larger the value, the better the adhesive strength at high temperatures.

[Melt viscosity of hot melt adhesive composition]
The sample was heated and melted, and the melt viscosity (mPa · s) at 120 ° C., 140 ° C., and 160 ° C. 27 was measured with a thermocell Brookfield viscometer. The smaller the value, the better the coating ease.

[Production example of tackifying resin]
After 100 parts by weight of benzene and 1.2 parts by weight of aluminum chloride were charged into the reaction vessel, 100 parts by weight of monomer mixtures A, B and C having the composition shown in Table 1 were gradually added and polymerization was carried out at 70 ° C. Thereafter, a mixture of methanol and aqueous ammonia was added to the reaction solution to decompose aluminum chloride, and the deactivated catalyst particles were separated by filtration. The filtrate was heated while blowing nitrogen to remove unreacted hydrocarbons. Saturated steam was blown from 240 ° C. to remove the oily polymer produced by the polymerization reaction. After confirming that there was almost no oil layer in the distillate, stop blowing steam and take out the melt, and when allowed to cool to room temperature, a tackifying resin (hydrocarbon resin) A, which is a yellow resinous substance, B and C were obtained. The aromatic monomer unit content, weight average molecular weight and softening point of these tackifying resins were measured and summarized in Table 1.

[Reference Example 1]
To the pressure-resistant reactor, 23.3 kg of cyclohexane, 2.6 mmol of N, N, N ′, N′-tetramethylethylenediamine (hereinafter referred to as TMEDA) and 1.43 kg of styrene were added and stirred at 40 ° C. Thereto, 176.2 mmol of n-butyllithium was added, and polymerization was performed for 1 hour while raising the temperature to 50 ° C. The polymerization conversion of styrene was 100% by weight. Subsequently, 6.50 kg of isoprene was continuously added to the reactor over 1 hour while controlling the temperature so as to maintain 50 to 60 ° C. After completing the addition of isoprene, polymerization was continued for an additional hour. The polymerization conversion rate of isoprene was 100%. Next, 61.7 mmol of dimethyldichlorosilane was added as a coupling agent and a coupling reaction was performed for 2 hours to form a styrene-isoprene-styrene block copolymer to be a block copolymer B. Thereafter, 2.07 kg of styrene was continuously added over 1 hour while controlling the temperature so as to maintain 50 to 60 ° C. After completion of the addition of styrene, polymerization was further performed for 1 hour to form a styrene-isoprene-styrene block copolymer to be a block copolymer A. The polymerization conversion of styrene was 100%. Thereafter, 352.4 mmol of methanol was added as a polymerization terminator and mixed well to stop the reaction. The amount of each reagent used in the reaction is summarized in Table 2. A part of the obtained reaction solution is taken out, the weight average molecular weight of each block copolymer and block copolymer composition, the weight ratio of each block copolymer in the block copolymer, the weight of each styrene polymer block The average molecular weight, the weight average molecular weight of each isoprene polymer block, the styrene unit content of each block copolymer, the styrene unit content of the block copolymer composition, and the vinyl bond content of the isoprene polymer block were determined. These values are shown in Table 3. To 100 parts of the reaction solution (containing 30 parts of the polymer component) thus obtained, 0.3 part of 2,6-di-tert-butyl-p-cresol was added as an antioxidant and mixed. The mixed solution was added dropwise to warm water heated to 85 to 95 ° C. little by little to volatilize the solvent to obtain a precipitate. The precipitate was pulverized and dried with hot air at 85 ° C. The block copolymer composition was recovered. The melt index was measured about the obtained block copolymer composition. The measured values are shown in Table 3.

[Reference Examples 2 and 3]
The blocks of Reference Example 2 and Reference Example 3 were the same as Reference Example 1 except that the amounts of styrene, n-butyllithium, TMEDA, isoprene, dimethyldichlorosilane and methanol were changed as shown in Table 2, respectively. The polymer composition was recovered. About the block copolymer composition of the reference example 2 and the reference example 3, the same measurement as the reference example 1 was performed. The results are shown in Table 3.

[Reference Example 4]
To a pressure-resistant reactor, 23.3 kg of cyclohexane, 2.2 mmol of TMEDA, and 1.85 kg of styrene were added, and 148.2 mmol of n-butyllithium was added to the mixture while stirring at 40 ° C., and the temperature was raised to 50 ° C. The polymerization was carried out for 1 hour. The polymerization conversion of styrene was 100%. Subsequently, 6.30 kg of isoprene was continuously added to the reactor over 1 hour while controlling the temperature so as to maintain 50 to 60 ° C. After completing the addition of isoprene, polymerization was continued for an additional hour. The polymerization conversion rate of isoprene was 100%. Further, 1.85 kg of styrene was continuously added over 1 hour while controlling the temperature so as to maintain 50 to 60 ° C. After completing the addition of styrene, polymerization was continued for an additional hour to form a styrene-isoprene-styrene block copolymer. The polymerization conversion of styrene was 100%. Thereafter, 296.4 mmol of methanol was added as a polymerization terminator and mixed well to stop the reaction. A part of the obtained reaction solution was taken out and subjected to the same measurement as in Reference Example 1. These values are shown in Table 3. The following operation was carried out in the same manner as in Reference Example 1, and the block copolymer composition of Reference Example 4 was recovered.

[Reference Example 5]
The block copolymer composition of Reference Example 5 in the same manner as Reference Example 1 except that the amounts of styrene, n-butyllithium, TMEDA, isoprene, dimethyldichlorosilane and methanol were changed as shown in Table 2, respectively. Was recovered. For the block copolymer composition of Reference Example 5, the same measurement as in Reference Example 1 was performed. The results are shown in Table 3.

[Example 1]
100 parts of the block copolymer composition obtained in Reference Example 1 was put into a stirring blade type kneader, and the aromatic monomer unit content obtained in the production example of the tackifying resin was 20% by weight. 167 parts of a certain tackifying resin A, 67 parts of a softening agent (trade name “Diana Process Oil NS-90S”, naphthenic process oil, manufactured by Idemitsu Kosan Co., Ltd.) and an antioxidant (trade name “Irganox 1010”, Ciba Specialty (Chemicals Co., Ltd.) 3 parts was added and the inside of the system was replaced with nitrogen gas, followed by kneading at 160 to 180 ° C. for 1 hour to prepare a hot melt adhesive composition of Example 1. The obtained hot-melt adhesive composition was applied to a polyester film having a thickness of 50 μm at a thickness of 30 μm, and the sample thus obtained was subjected to tackiness, adhesive strength, holding power, shear fracture temperature, and The melt viscosity was evaluated. The results are shown in Table 4.

[Examples 2-6, Comparative Examples 1-6]
The hot melt adhesives of Examples 2-6 and Comparative Examples 1-6 were the same as Example 1 except that the block copolymer composition and tackifying resin used were changed as shown in Table 4. A composition was prepared. The obtained hot melt adhesive composition was evaluated in the same manner as in Example 1. The results are shown in Table 4.

  Table 4 shows the following. That is, the hot melt adhesive composition of the present invention is excellent in adhesive strength and holding power, and has a low melt viscosity over a wide temperature range. It can be said that it is long, and it is also excellent in tackiness and shear fracture temperature (Examples 1 to 6). On the other hand, the hot melt adhesive composition obtained by using the block copolymer composition of Reference Example 4 consisting only of a symmetric aromatic vinyl-conjugated diene-aromatic vinyl block copolymer, The melt viscosity at 120 ° C. was high, and coating at a relatively low temperature was difficult (Comparative Examples 1, 3, and 5). Further, it comprises an asymmetric aromatic vinyl-conjugated diene-aromatic vinyl block copolymer different from the block copolymer A used in the present invention, and a symmetric aromatic vinyl-conjugated diene-aromatic vinyl block copolymer. Those using the block copolymer composition of Reference Example 5 consisting of a block copolymer have a particularly high melt viscosity at 120 ° C. and are difficult to apply at a relatively low temperature. It was inferior (Comparative Examples 2, 4, 6). Moreover, the hot-melt adhesive composition obtained using the tackifier resin C containing no aromatic monomer unit was inferior in holding power (Comparative Examples 5 and 6).

Claims (3)

It contains a block copolymer composition comprising a block copolymer A represented by the following general formula (A) and a block copolymer B represented by the following general formula (B), and a tackifying resin. A hot melt adhesive composition comprising:
The weight ratio (A / B) of the block copolymer A and the block copolymer B in the block copolymer composition is 10/90 to 90/10, and the aromatic monomer unit content of the tackifying resin A hot-melt adhesive composition in which is 1 to 70% by weight.
^{Ar1 a -D a -Ar2 a (A} )
(Ar ^b -D ^b ) _n -X (B)
(In the general formula (A) and (B), Ar @ 1 ^a and Ar ^b are each an aromatic vinyl polymer block having a weight average molecular weight of 6,000 to 20,000, Ar @ 2 ^a has a weight average molecular weight of 22,000 to 400,000 Is an aromatic vinyl polymer block, D ^a and D ^b are each a conjugated diene polymer block having a vinyl bond content of 1 to 20 mol%, and X is a single bond or a residue of a coupling agent. , N is an integer of 2 or more.)   In the block copolymer composition, the ratio of the aromatic vinyl monomer unit to the total monomer units constituting the polymer component in the block copolymer composition is 13 to 85% by weight. The hot melt adhesive composition according to claim 1.   The hot-melt adhesive composition according to claim 1 or 2, further comprising a softening agent.