JP2012207127A - Hot-melt pressure-sensitive adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot-melt pressure-sensitive adhesive having excellent softener retention, die-cut properties, retaining force and tackiness in a low-temperature environment.SOLUTION: The hot-melt pressure-sensitive adhesive composition includes a block copolymer component which comprises a block copolymer A being an aromatic vinyl-conjugated diene-aromatic vinyl-triblock copolymer having a specific constitution and a block copolymer B composed of an aromatic vinyl polymer block and a conjugated diene polymer block as terminal blocks and in which the content of the block copolymer A is 5-90 wt.% based on the total weight of the block copolymer A and the block copolymer B, wax incompatible with the block copolymer component, a softener compatible with the block copolymer component and a tackifier resin.

Description

  The present invention relates to a hot-melt adhesive composition, and more specifically, it has excellent softener retention, die-cutting properties, holding power, and tackiness in a low temperature environment, and is particularly useful as an adhesive for labels. The present invention relates to a hot-melt adhesive composition.

  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. One typical application of a hot melt adhesive is to use the label as an adhesive.

  When manufacturing a label industrially, usually a hot melt adhesive is melted, and the melted hot melt adhesive is applied to a substrate such as a release paper by a coating device such as a die coater. A manufacturing method is employed in which the obtained pressure-sensitive adhesive sheet is cut into a certain size by cutting with a die cutter.

  In this manufacturing method, the productivity of the label depends greatly on the properties of the hot melt adhesive used, and in particular, the coating temperature of the hot melt adhesive and the die cutting property (when the yarn is cut by a die cutter) The ease of cutting to a certain size without pulling or adhering to the die has an extremely large influence on the productivity of the label.

  For this reason, studies have been made on reducing the temperature at which coating is possible and improving die-cutting properties for hot melt adhesives used for producing labels. For example, Patent Document 1 discloses that a hot-melt adhesive composition is composed of a radial styrene-isoprene-styrene block copolymer and a compatible polymer, a tackifier resin, a plasticizer, and the like to form a relatively low temperature. It is described that a hot melt adhesive composition suitable for label adhesion to a bottle can be obtained. Further, in Patent Document 2, a pressure-sensitive adhesive is formed by blending a styrene-isoprene-styrene block copolymer with a tackifier, a styrene-isoprene block copolymer, a plasticizer, and the like, so that cutting with a die is easy. It is described that a pressure-sensitive adhesive suitable for labels can be obtained. Furthermore, in Patent Document 3, a block copolymer having a specific structure is blended with a specific polymer, a tackifier resin, a softening agent, and the like to constitute a label adhesive composition for low temperature. It is described that an adhesive composition for a label can be obtained which is easy to apply and has a good die-cut property.

  However, in the adhesive composition formed by blending a softening agent (plasticizer) with a block copolymer as described in Patent Documents 1 to 3, the blending of the softening agent reduces the coating temperature. Although it contributes to improvement in tackiness and tackiness, there is a problem that when the blending amount of the softening agent is increased, the blended softening agent begins to exude and contaminates the object to be bonded. Moreover, even with the improved adhesive composition as described in Patent Documents 1 to 3, further improvements in die-cutting properties have been demanded depending on the application. Therefore, there has been a demand for a hot-melt adhesive composition that achieves a high level of performance (softener retention) and die-cutting properties that prevent the blended softener from bleeding.

Japanese Patent Laid-Open No. 10-30079 JP-T-2001-504519 International Publication No. 2010/113883

  The present invention provides a hot-melt adhesive composition that has both softener retention and die-cutting properties, and is excellent in holding power, which is the basic performance of an adhesive, and tackiness in a low-temperature environment. The purpose is to provide.

  As a result of intensive studies to achieve the above object, the present inventors have developed an asymmetric aromatic vinyl-conjugated diene-aromatic vinyl block copolymer in which two aromatic vinyl polymer blocks have different weight average molecular weights. The adhesive composition obtained by blending a block copolymer having a specific structure and further blending a tackifier resin, a softener and a wax has a softener retention property, die cut property, retention force and low temperature environment. We have found that both of the tack properties below are excellent. The present invention has been completed based on this finding.

  Thus, according to the present invention, the block copolymer A represented by the following general formula (A) and the block copolymer comprising an aromatic vinyl polymer block and a conjugated diene polymer block as terminal blocks are provided. A block copolymer component comprising a polymer B, wherein the block copolymer A accounts for 5 to 90% by weight of the total weight of the block copolymer A and the block copolymer B, and the block copolymer There is provided a hot melt adhesive composition comprising a wax incompatible with the components, a softening agent compatible with the block copolymer component, and a tackifying resin.

Ar1-D-Ar2 (A)

  In the general formula (A), Ar1 represents an aromatic vinyl polymer block having a weight average molecular weight of 10,000 to 25,000, Ar2 represents an aromatic vinyl polymer block having a weight average molecular weight of 15,000 to 200,000, and D represents a conjugated diene weight. The ratio of the weight average molecular weight of the aromatic vinyl polymer block represented by Ar1 to the weight average molecule of the aromatic vinyl polymer block represented by Ar2 is 0.1 to 0.9.

  In the hot melt adhesive composition, the wax content is 1 to 50 parts by weight and the softener content is 10 to 300 parts by weight with respect to 100 parts by weight of the block copolymer component. The tackifying resin content is preferably 10 to 500 parts by weight.

  The hot melt adhesive composition is preferably used as a label adhesive.

  According to the present invention, a hot-melt adhesive composition that has both softener retention and die-cutting properties, and is excellent in holding power and tackiness in a low-temperature environment, which are the basic performance of an adhesive. A thing is obtained. And the hot-melt adhesive composition of this invention can contribute greatly to the improvement of label productivity by using as an adhesive agent of a label.

  The hot melt adhesive composition of the present invention comprises a block copolymer component comprising at least a block copolymer A and a block copolymer B, a wax incompatible with the block copolymer component, and a block A softener that is compatible with the copolymer component and a tackifying resin are contained. The block copolymer A, which is one of the essential components of the block copolymer component constituting the hot melt adhesive composition of the present invention, is represented by the following general formula (A), and has different weight averages. An aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having two aromatic vinyl polymer blocks having a molecular weight.

  Ar1-D-Ar2 (A)

  In the above general formula (A), Ar1 represents an aromatic vinyl polymer block having a weight average molecular weight of 10,000 to 25,000, Ar2 represents an aromatic vinyl polymer block having a weight average molecular weight of 15,000 to 200,000, and D is conjugated. The ratio of the weight average molecular weight of the aromatic vinyl polymer block represented by Ar1 to the weight average molecule of the aromatic vinyl polymer block represented by Ar2 represents a diene polymer block is 0.1 to 0.9. .

  The block copolymer B, which is another essential component of the block copolymer component, comprises an aromatic vinyl polymer block and a conjugated diene polymer block, each of which is a polymer block located at the end of the polymer chain (ie, , Terminal block).

  The aromatic vinyl polymer block of the block copolymer A and the block copolymer B is a polymer block having an aromatic vinyl monomer unit as a main constituent unit. 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.

  The aromatic vinyl polymer blocks of the block copolymer A and the block copolymer B may each contain a monomer unit other than the aromatic vinyl monomer unit. 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 the aromatic vinyl monomer unit in each aromatic vinyl polymer block is not particularly limited as long as the aromatic vinyl monomer unit is the main constituent unit, but it is 20% by weight or less. It is preferably 10% by weight or less, particularly preferably substantially 0% by weight.

  The conjugated diene polymer block of the block copolymer A and the block copolymer B is a polymer block having a conjugated diene monomer unit as a main constituent unit. 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.

  Each of the conjugated diene polymer blocks of the block copolymer A and the block copolymer B may 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 not particularly limited as long as the conjugated diene monomer unit is the main constituent unit, but it is 20% by weight or less. Is preferably 10% by weight or less, particularly preferably 0% by weight.

  The block copolymer A constituting the hot melt adhesive composition of the present invention is an aromatic vinyl polymer block (Ar1) having a relatively small weight average molecular weight as represented by the general formula (A). ), A conjugated diene polymer block (D) and an aromatic vinyl polymer block (Ar2) having a relatively large weight average molecular weight are connected in this order, asymmetric aromatic vinyl-conjugated diene-aromatic vinyl It is a triblock copolymer. The aromatic vinyl polymer block (Ar1) having a relatively small weight average molecular weight has a weight average molecular weight (Mw (Ar1)) of 10,000 to 25,000, preferably 11,000 to 23,000, and 12,000 to 21,000. Is more preferable. If Mw (Ar1) is too small, the resulting hot-melt adhesive composition may have low holding power, and if it is too large, the melt viscosity of the hot-melt adhesive composition will be extremely high. There is a fear. The weight average molecular weight (Mw (Ar2)) of the aromatic vinyl polymer block (Ar2) having a relatively large weight average molecular weight is 15000 to 200000, preferably 18000 to 150,000, preferably 20000 to 100000. More preferably. If Mw (Ar2) is too small, the resulting hot melt adhesive composition may have a relatively high melt viscosity at a low temperature, and Mw (Ar2) is too large. May be difficult to manufacture. In the block copolymer A, the aromatic vinyl polymer having a relatively small weight average molecular weight relative to the weight average molecule (Mw (Ar2)) of the aromatic vinyl polymer block (Ar2) having a relatively large weight average molecular weight. The ratio (Mw (Ar1) / Mw (Ar2)) of the weight average molecular weight (Mw (Ar1)) of the combined block (Ar1) is 0.1 to 0.9, and is 0.2 to 0.7. Is more preferable, and 0.25 to 0.65 is more preferable. If Mw (Ar1) / Mw (Ar2) is too small, the resulting hot melt adhesive composition may have a relatively high melt viscosity at a low temperature, and Mw (Ar1) / Mw ( If Ar2) is too large, the resulting hot melt adhesive composition may have a low holding power.

  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.

  The vinyl bond content of the conjugated diene polymer block (D) of the block copolymer A (the ratio of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units) is particularly limited. Although it is not usually, it is 1-20 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)) of the conjugated diene polymer block (D) of the block copolymer A is not particularly limited, but is usually 20000 to 200000, preferably 30000 to 170000, preferably 35000 to 150,000. It is more preferable that

  The content of the aromatic vinyl monomer unit with respect to all the monomer units of the block copolymer A is not particularly limited, but is preferably 20% by weight or more, and more preferably 25 to 60% by weight. More preferably, it is 30 to 50% by 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 80,000-300000, It is preferable that it is 100,000-27,000, and it is more preferable that it is 120,000-250,000.

  The block copolymer A in the block copolymer component of the hot melt adhesive composition of the present invention may be composed of only one type of block copolymer A having a substantially single structure. It may be constituted by two or more types of block copolymers A having substantially different configurations.

  The block copolymer B constituting the hot melt adhesive composition of the present invention is a block copolymer having an aromatic vinyl polymer block and a conjugated diene polymer block as terminal blocks. The structure is not particularly limited, and may be a linear block copolymer or a radial block copolymer. When the block copolymer B is a linear block copolymer, one end of the polymer chain is constituted by an aromatic vinyl polymer block, and the other is constituted by a conjugated diene polymer block. The polymer block may be a diblock copolymer in which these polymer blocks are bonded directly or through a residue of a coupling agent, or these polymer blocks may be one or more other polymers. It may be a block copolymer bonded through a block. Further, when the block copolymer B is a radial block copolymer, it may be any one having at least one aromatic vinyl polymer block and one conjugated diene polymer block, Other configurations are not particularly limited.

  In the hot-melt adhesive composition of the present invention, as the block copolymer B, an aromatic vinyl polymer block and a conjugated diene polymer block are bonded directly or via a residue of a coupling agent. It is preferable to contain a block copolymer, and it is particularly preferable to contain a block copolymer represented by the following general formula (B).

Arb-Db (B)

  In the above general formula (B), Arb represents an aromatic vinyl polymer block having a weight average molecular weight of 8000 to 25000, and Db represents a conjugated diene polymer block.

  The block copolymer represented by the general formula (B) is an aromatic formed by bonding an aromatic vinyl polymer block (Arb) having a specific weight average molecular weight and a conjugated diene polymer block (Db). Vinyl-conjugated diene diblock copolymer. As the aromatic vinyl monomer used for constituting the aromatic vinyl polymer block (Arb), the same aromatic vinyl monomer used for constituting the block copolymer A may be used. it can. The weight average molecular weight (Mw (Arb)) of the aromatic vinyl polymer block (Arb) constituting the block copolymer represented by the general formula (B) is 8000 to 25000, and 9000 to 23000. It is preferable that it is 15000-21000. The weight average molecular weight (Mw (Arb)) of the aromatic vinyl polymer block of the block copolymer represented by the general formula (B) has a relatively small weight average molecular weight of the block copolymer A. It is more preferable that the weight average molecular weight (Mw (Ar1)) of the aromatic vinyl polymer block (Ar1) is substantially equal.

  As the conjugated diene monomer used for constituting the conjugated diene polymer block (Db) of the block copolymer represented by the general formula (B), it is used for constituting the block copolymer A. The same conjugated diene monomer can be used. In addition, you may perform hydrogenation reaction with respect to a part of unsaturated bond of a conjugated diene polymer block (Db). Further, the vinyl bond content of the conjugated diene polymer block (Db) constituting the block copolymer represented by the general formula (B) is not particularly limited, but is usually 1 to 30 mol%, and 2 It is preferably ˜25 mol%, more preferably 3 to 20 mol%. The vinyl bond content of the conjugated diene polymer block (Db) constituting the block copolymer represented by the general formula (B) is the same as that of the conjugated diene polymer block (D) of the block copolymer A. It is preferably substantially equal to the vinyl bond content.

  The weight average molecular weight (Mw (Db)) of the conjugated diene polymer block (Db) constituting the block copolymer represented by the general formula (B) is not particularly limited, but is usually 20000 to 200000, It is preferably 30000 to 170000, more preferably 35000 to 150,000. In addition, the weight average molecular weight (Mw (Db)) of the conjugated diene polymer block of the block copolymer represented by the above general formula (B) is the conjugated diene polymer block (D) of the block copolymer A. The weight average molecular weight (Mw (D)) is preferably substantially equal.

  Although content of the aromatic vinyl monomer unit with respect to all the monomer units of the block copolymer B which comprises the hot-melt adhesive composition of this invention is not specifically limited, Usually, it is 10 to 35 weight% Yes, it is preferably 12 to 30% by weight, and more preferably 13 to 25% by weight. Moreover, although the weight average molecular weight as the whole block copolymer B is not specifically limited, Usually, it is 70000-250,000, it is preferable that it is 80000-210000, and it is more preferable that it is 90000-180000.

  The block copolymer component of the hot melt adhesive composition of the present invention may contain one block copolymer B having a substantially single structure, or substantially It may contain two or more block copolymers B having different structures.

  In the block copolymer component constituting the hot melt adhesive composition of the present invention, the ratio of the block copolymer A to the total weight of the block copolymer A and the block copolymer B is 5 It is -90 weight%, It is preferable that it is 10-70 weight%, and it is more preferable that it is 20-60 weight%. If this ratio is too small, the resulting hot melt adhesive composition may be inferior in softener retention and holding power. If this ratio is too large, the resulting hot melt adhesive composition may be obtained. There exists a possibility that a thing may be inferior to the tack property in a low-temperature environment.

  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 each polymer block constituting the block copolymer A and the block copolymer B is not particularly limited. Are usually 1.1 or less, preferably 1.05 or less.

  The block copolymer component constituting the hot melt adhesive composition of the present invention may be composed of only the block copolymer A and the block copolymer B, but the block copolymer A and the block copolymer A block copolymer other than the copolymer B may be contained. Examples of such block copolymers include aromatic vinyl-conjugated diene-aromatic vinyl triblock copolymers and radial aromatic vinyl-conjugated diene block copolymers having a different structure from block copolymer A. It can be mentioned, but is not limited to these. In the block copolymer component, the amount of the block copolymer other than the block copolymer A and the block copolymer B is preferably 20% by weight or less, and more preferably 10% by weight or less.

  A block copolymer component comprising a block copolymer A, a block copolymer B, and a block copolymer other than the block copolymer A and the block copolymer B which may be optionally contained. The ratio of the aromatic vinyl monomer unit to the whole (in the following description, sometimes referred to as “total aromatic vinyl monomer unit content”) is not particularly limited. It is preferably ˜60% by weight, more preferably 15 to 55% by weight, still more preferably 20 to 50% by weight. 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 content of the aromatic vinyl monomer unit is determined by taking into account the content of the aromatic vinyl monomer unit in each block copolymer constituting the block copolymer component. It is possible to adjust easily by adjusting. In the case where all the polymer components constituting the block copolymer component are composed only of an aromatic vinyl monomer unit and a conjugated diene monomer unit, Rubber Chem. Technol. , 45, 1295 (1972), ozonolysis of the block copolymer component followed by reduction with lithium aluminum hydride results in decomposition of the conjugated diene monomer unit portion and aromatic vinyl monomer. Since only the body unit portion can be taken out, the entire aromatic vinyl monomer unit content can be easily measured.

  The weight average molecular weight of the block copolymer component as a whole comprising the block copolymer A, the block copolymer B, and a block copolymer other than the block copolymer A and the block copolymer B which may be contained in some cases is Although it is not specifically limited, it is usually 70000-300000, it is preferable that it is 85000-270000, and it is more preferable that it is 100000-250,000. 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 block copolymer component is not particularly limited, but is usually 1.01 to 10 Yes, it is preferably 1.03 to 5, more preferably 1.05 to 3.

  The method for obtaining the block copolymer component used in the present invention is not particularly limited. For example, each block copolymer can be produced separately according to a conventional polymerization method, and can be produced by mixing them according to a conventional method such as kneading or solution mixing. However, from the viewpoint of obtaining the block copolymer component with good productivity, the production method described below is preferable.

  That is, the block copolymer component comprising the block copolymer A and the block copolymer B 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 a solution containing an aromatic vinyl-conjugated diene block copolymer having an active terminal obtained in the step (2) above, Step (4) of adding block so as to be less than 1 molar equivalent with respect to the active terminal of the aromatic vinyl-conjugated diene block copolymer having a terminal, step (4): Step (5) of adding an aromatic vinyl monomer to the resulting solution to form the block copolymer A: step of recovering a polymer component from the solution obtained in the step (4) above

  In the above production method, first, an aromatic vinyl monomer is polymerized using a polymerization initiator in a solvent (step (1)). 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 order to control the structure of each polymer block of each block copolymer, a Lewis base compound may be added to the reactor used for the polymerization. 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 terminal is the aromatic vinyl polymer block (Ar1) having a relatively small weight average molecular weight of the block copolymer A and the aromatic vinyl polymer block of the block copolymer B. It constitutes an aromatic vinyl polymer block. 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 terminal obtained as described above (step (2)). By adding the 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 having an active end is obtained. The amount of the conjugated diene monomer used here is such that the resulting conjugated diene polymer chain is a conjugated diene polymer block (D) of the target block copolymer A and a conjugated diene polymer block of the block copolymer B. Having a weight average molecular weight of

  In the next step, a polymerization terminator is added to the solution containing the aromatic vinyl-conjugated diene block copolymer having active ends obtained as described above, and the aromatic vinyl-conjugated diene block copolymer having active ends is added. It adds so that it may become less than 1 molar equivalent with respect to the active terminal of a coalescence (process (3)). Addition of a polymerization terminator to a solution containing an aromatic vinyl-conjugated diene block copolymer having an active end deactivates the active end of the aromatic vinyl-conjugated diene block copolymer having an active end. A block copolymer B which is an aromatic vinyl-conjugated diene diblock copolymer is formed.

  The polymerization terminator added at this process is not specifically limited, A conventionally well-known polymerization terminator can be especially used without a restriction | limiting. Particularly suitable polymerization terminators include alcohols such as methanol, ethanol, propanol, butanol and isopropanol.

  The amount of the polymerization terminator added in this step needs to be an amount that is less than 1 molar equivalent relative to the active end of the aromatic vinyl-conjugated diene block copolymer having an active end. This is because the aromatic vinyl-conjugated diene block copolymer having an active terminal needs to remain in the solution in order to perform the next step of forming the block copolymer A. The amount of the polymerization terminator is preferably 0.10 to 0.90 molar equivalent, more preferably 0.15 to 0.70 molar equivalent, relative to the active terminal of the polymer. Since the amount of the polymerization terminator added in this step determines the amount of the block copolymer B, the amount of the polymerization terminator depends on the composition of the target block copolymer component. Just decide.

  The reaction conditions for the polymerization termination reaction are not particularly limited, and may usually be set within the same range as the polymerization reaction conditions described above.

  In the next step, an aromatic vinyl monomer is added to the solution obtained as described above (step (4)). When an aromatic vinyl monomer is added to the solution, an aromatic vinyl polymer chain is formed from the end of the aromatic vinyl-conjugated diene block copolymer having an active terminal remaining without reacting with the polymerization terminator. . This aromatic vinyl polymer chain constitutes an aromatic vinyl polymer block (Ar2) having a relatively large weight average molecular weight of the block copolymer A. Therefore, the amount of the aromatic vinyl monomer used at this time is determined according to the target weight average molecular weight of the aromatic vinyl polymer block (Ar2). By the step of adding the aromatic vinyl monomer, an asymmetric aromatic vinyl-conjugated diene-aromatic vinyl triblock copolymer that forms the block copolymer A is formed. A solution containing copolymer A and block copolymer B is obtained. Before the step of adding the aromatic vinyl monomer, the conjugated diene monomer is added to a solution containing an aromatic vinyl-conjugated diene block copolymer having an active end that has not reacted with the polymerization terminator. It may be added. When the conjugated diene monomer is added as described above, the weight average molecular weight of the conjugated diene polymer block (D) of the block copolymer A can be increased as compared with the case where the conjugated diene monomer is not added.

  In the next step, the target polymer component is recovered from the solution obtained as described above (step (5)). 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 polymer component is recovered as a slurry by applying steam stripping or the like, it is dehydrated using an arbitrary dehydrator such as an extruder-type squeezer to obtain a crumb having a moisture content of a predetermined value or less. The crumb may be dried using any dryer such as a band dryer or an expansion extrusion dryer. The block copolymer component obtained as described above may be processed into pellets or the like according to a conventional method, and then used for production of a hot melt adhesive composition or the like.

  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, compared with the case where each polymer is produced and mixed individually. The desired block copolymer component can be obtained with extremely excellent productivity.

  The hot melt adhesive composition of the present invention comprises a block copolymer component comprising the block copolymer A and the block copolymer B as described above, and is incompatible with the block copolymer component. It contains a wax, a softening agent that is compatible with the block copolymer component, and a tackifying resin. As the tackifying resin used in the present invention, conventionally known tackifying resins can be used. Specifically, rosin; modified rosins such as disproportionated rosin and dimerized rosin; esterified product of polyhydric alcohol such as glycol, glycerin and pentaerythritol and rosin or modified rosins; terpene resin; aliphatic , Aromatic, alicyclic or aliphatic-aromatic copolymer hydrocarbon resins or their hydrides; phenol resins; coumarone-indene resins. Particularly preferred tackifying resins are aliphatic or aliphatic-aromatic copolymer hydrocarbon resins that are compatible with the polymer components used in the present invention. The content of the tackifier resin in the hot melt adhesive composition of the present invention is not particularly limited, but is usually 10 to 500 parts by weight, preferably 50 to 350 parts by weight per 100 parts by weight of the block copolymer component. Part, more preferably 70 to 250 parts by weight. In addition, a tackifier resin may be used individually by 1 type, and may be used in combination of 2 or more type.

  The wax used in the present invention is a solid oily organic compound at room temperature (23 ° C.) and is incompatible with the block copolymer component in a molten state. The hot melt adhesive composition of the present invention exhibits excellent softener retention and die cutting properties when such a wax is contained. The type of wax that can be used is not particularly limited. For example, polyethylene wax, ethylene vinyl acetate copolymer wax, oxidized polyethylene wax, paraffin wax, microcrystalline wax, Fischer-Tropsh wax, oxidized Fischer-Tropsh wax, hydrogenated From castor oil wax, polypropylene wax, by-product polyethylene wax, hydroxylated stearamide wax and the like, those which are incompatible with the block copolymer component to be used can be selected and used. Here, whether or not it is incompatible with the block copolymer component used by the wax can be confirmed by the following method. That is, the block copolymer component and the wax are melted and mixed at the same weight, and then the mixture is obtained by cooling to room temperature (23 ° C.) by standing at room temperature (23 ° C.). If possible, it can be said that the wax is incompatible with the block copolymer component. In addition, the wax which shows incompatibility with respect to the block copolymer component to be used may be used individually by 1 type, and may be used in combination of 2 or more type.

  In the present invention, the wax that is particularly preferably used is a wax having a melting point of 50 to 200 ° C. (more preferably 60 to 160 ° C.), and among them, a polyethylene wax or an ethylene vinyl acetate copolymer wax having this melting point is suitable. It is. The wax content in the hot melt adhesive composition of the present invention is not particularly limited, but is usually 1 to 50 parts by weight, preferably 2 to 45 parts by weight per 100 parts by weight of the block copolymer component. Part, more preferably 5 to 30 parts by weight. When the content of the wax is within this range, the resulting hot melt adhesive composition is particularly excellent in softener retention and die cutting properties.

  The softening agent used in the present invention is an organic compound that is liquid at room temperature (23 ° C.) and exhibits compatibility with the block copolymer component in a molten state. Here, whether or not the softener is compatible with the block copolymer component can be confirmed by the following method. That is, the mixture obtained by melt-mixing the block copolymer component and the softening agent at the same weight and then cooling to room temperature (23 ° C.) by standing at room temperature (23 ° C.) is visually turbid. If it cannot be confirmed, it can be said that the softener is compatible with the block copolymer component. The type of softener used is not particularly limited as long as it is compatible with the block copolymer component, and specifically, added to a normal hot melt adhesive composition, Aromatic, paraffinic or naphthenic process oils; liquid polymers such as polybutene and polyisobutylene can be used, and paraffinic process oils or naphthenic process oils are particularly preferred. In addition, a softener may be used individually by 1 type and may be used in combination of 2 or more type.

  Further, the content of the softening agent in the hot melt adhesive composition of the present invention is not particularly limited, but is usually 10 to 300 parts by weight, preferably 30 to 250 parts per 100 parts by weight of the block copolymer component. Parts by weight, more preferably 50 to 220 parts by weight. Since the hot melt adhesive composition of the present invention is excellent in softener retention, a relatively large amount of softener can be blended. By blending the softener in such an amount, The hot melt adhesive composition can be easily applied at a relatively low temperature and has excellent tackiness in a low temperature environment.

  The hot melt adhesive composition of the present invention may contain a polymer other than the essential components as described above. Examples of such polymers include aromatic vinyl-conjugated diene random polymers such as conjugated diene homopolymers such as polybutadiene and polyisoprene, (styrene-butadiene) random copolymers, and (styrene-isoprene) random copolymers. Copolymers, aromatic vinyl homopolymers such as polystyrene, isobutylene polymers, acrylic polymers, ester polymers, ether polymers, urethane polymers, polyvinyl chloride, etc. at room temperature (23 ° C.) Examples include polymers having elasticity, but are not limited thereto. In the hot melt adhesive composition of the present invention, the content of these polymers is preferably 20% by weight or less, preferably 10% by weight or less, based on the weight of the block copolymer component. Is more preferable.

  Moreover, antioxidant can be added to the hot-melt adhesive composition of this invention as needed. The type is not particularly limited, and for example, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl- Hindered phenol compounds such as 4-hydroxyphenyl) propionate, 2,6-di-t-butyl-p-cresol, di-t-butyl-4-methylphenol; thiodicarboxy such as dilauryl thiopropionate Rate esters; phosphites such as tris (nonylphenyl) phosphite can be used. Although the usage-amount of antioxidant is not specifically limited, It is 10 parts weight or less normally with respect to 100 weight part of block copolymer components, 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 component and other components is not particularly limited. For example, after each component is dissolved in a solvent and uniformly mixed And a method of removing the solvent by heating and the like, and a method of melting and mixing each component with a kneader. From the viewpoint of performing mixing more efficiently, melt mixing is preferable among these methods. In particular, a block copolymer component, a softening agent, and a tackifier resin are previously melt-mixed, and a wax is added to the melt mixture. In addition, a method of further performing melt mixing is preferably used. In addition, the temperature at the time of performing melt mixing is not particularly limited, but is usually in the range of 100 to 200 ° C.

  In obtaining the hot melt adhesive composition of the present invention, for example, one block copolymer B (a block copolymer represented by the general formula (B)) is blocked in the reactor. After synthesizing with the polymer A, another block copolymer B (a block copolymer represented by the general formula (B)) can be further mixed.

  The use of the hot melt adhesive composition of the present invention is not particularly limited, and can be used for various adhesives to which hot melt adhesion can be applied. It is preferably used. For example, the hot-melt adhesive composition of the present invention is melted by heating and then cut by a die to a certain size, and then is used for fine paper, art paper, cast paper, thermal paper, foil paper. After being coated on a paper substrate such as polyethylene terephthalate, a synthetic resin film such as polyethylene terephthalate, or a film substrate such as cellophane film, or coated on a release paper, a label is produced by transferring to the substrate. Since the hot-melt adhesive composition of the present invention has good softener retention and die-cutting properties, it contributes to the reduction of defective products and the improvement of productivity in the production of such labels. . Moreover, the obtained label has excellent holding power and tackiness in a low temperature environment. Although the use of the obtained label is not particularly limited, it can be used, for example, as a product label or a variable information label for containers / packaging of food, beverages, and alcoholic beverages. It can also be used as a label for logistics, electrical / precision equipment, medicine / medical care, cosmetics / toiletries, stationery / OA, and automobiles.

  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)
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 component]
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 of block copolymer]
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 block copolymer 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 component (whole)]
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.

[Tackability of hot-melt adhesive composition under low temperature environment]
According to FINAT-1991 FTM-9 (Quick-stick tack measurement), the loop tack under an atmosphere at 5 ° C. was measured to evaluate the tackiness. The larger the value, the better the tackiness in a low temperature environment.

[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 × 104 Pa and a temperature of 40 ° C. The larger the value, the better the holding power.

[Softener retention of hot melt adhesive composition]
Based on the degree of discoloration confirmed by visually observing the high quality paper on the back of the adhesive tape after the sample was affixed to high quality paper as a 50 mm x 50 mm adhesive tape and aged for 2 weeks under a load of 2 kg and 80 ° C for 1 week. The softener retention was evaluated according to the following criteria.
Excellent: Discoloration is not seen on high-quality paper.
Good: Partial discoloration is observed on high-quality paper.
Impossible: Discoloration is seen over the entire quality paper on the back of the adhesive tape application area.

[Die-cutting property of hot-melt adhesive composition]
A sample is pasted on a release paper as an A4 size adhesive film, and after 10 sheets are cut using a guillotine cutter, the degree of adhesive residue on the blade is confirmed by visual inspection of the blade of the guillotine cutter Based on the above, the die cutting property was evaluated according to the following criteria.
Excellent: No glue residue is seen on the blade.
Good: Partial glue residue is seen on the blade.
Impossible: Adhesive residue is seen over the entire area of the blade that contacts the sample during cutting.

[Reference Example 1]
To the pressure resistant reactor, 23.3 kg of cyclohexane, 3.50 mmol of N, N, N ′, N′-tetramethylethylenediamine (hereinafter referred to as TMEDA) and 1.75 kg of styrene were added and stirred at 40 ° C. Then, 116.7 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, 7.00 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, 82.3 mmol of methanol is added as a polymerization terminator, and the reaction is carried out for 1 hour, and a part of the active ends of the styrene-isoprene block copolymer having active ends is deactivated, thereby causing the block copolymer B and The resulting styrene-isoprene diblock copolymer was formed. Thereafter, 1.25 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 triblock copolymer to be a block copolymer A. The polymerization conversion of styrene was 100%. Thereafter, 233.4 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 1. To 100 parts of the reaction solution (containing 30 parts of the polymer component) thus obtained, 0.3 part of 2,6-di-t-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 composition was recovered. A part of the obtained reaction solution is taken out, the weight average molecular weight of each block copolymer contained, the weight ratio of each block copolymer in the polymer component, the weight of the styrene polymer block of each block copolymer Average molecular weight, weight average molecular weight of isoprene polymer block of each block copolymer, styrene unit content of each block copolymer, styrene unit content of block copolymer component (whole) and isoprene of each block copolymer The vinyl bond content of the polymer block was determined. These values are shown in Table 2.

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

[Reference Example 3]
23.3 kg of cyclohexane, 3.75 mmol of N, N, N ′, N′-tetramethylethylenediamine (hereinafter referred to as TMEDA) and 1.65 kg of styrene are added to the pressure-resistant reactor and stirred at 40 ° C. Then, 125.0 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, 8.35 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, 35.0 mmol of dimethyldichlorosilane was added as a coupling agent, and the reaction was continued for 2 hours by controlling the temperature so as to maintain 50 to 60 ° C., whereby the styrene-isoprene block copolymer having an active terminal was reacted. By coupling a part, a styrene-isoprene-styrene triblock copolymer having a substantially symmetrical structure was formed. Thereafter, 250.0 mmol of methanol was added as a polymerization terminator and mixed well to stop the reaction, thereby deactivating the active terminal of the styrene-isoprene block copolymer having the remaining active terminal, thereby blocking the block copolymer. A styrene-isoprene diblock copolymer to be the polymer B was formed. The amount of each reagent used in the reaction is summarized in Table 1. The reaction solution obtained as described above was treated in the same manner as in Reference Example 1, and the composition of Reference Example 3 was recovered. Further, a part of the obtained reaction solution was taken out, and the same measurement as in Reference Example 1 was performed. These measured values are shown in Table 2.

[Example 1]
100 parts of the composition obtained in Reference Example 1 was put into a stirring blade type kneader, and 150 parts of a tackifier resin (trade name “Quinton R100”, aliphatic hydrocarbon resin, manufactured by Nippon Zeon Co., Ltd.), naphthene -Based process oil (trade name “Diana Process Oil NS-90S”, manufactured by Idemitsu Kosan Co., Ltd.) and an antioxidant (trade name “Irganox 1076”, octadecyl-3- (3,5-di-t-butyl) After adding 1.5 parts of (-4-hydroxyphenyl) propionate (manufactured by Ciba Specialty Chemicals) and replacing the system with nitrogen gas, the mixture was kneaded at 160 to 180 ° C. for 1 hour. Then, 13 parts of polyethylene wax (trade name “A-C 8”, melting point 113 ° C., manufactured by Honeywell) was added to the obtained kneaded product, and the mixture was further kneaded at 160 to 180 ° C. for 30 minutes. 1 hot melt adhesive composition was prepared. And the hot-melt adhesive composition obtained by applying to a 55 μm-thick polyester film was coated, and the sample obtained thereby had tackiness, holding power, softener retention and die-cut in a low-temperature environment. Sex was evaluated. These results are shown in Table 3.

[Examples 2-6, Comparative Examples 1-4]
The hot melt adhesive compositions of Examples 2 to 6 and Comparative Examples 1 to 4 were the same as Example 1 except that the types and amounts of the compositions and additives used were changed as shown in Table 3. A product was prepared. In Table 3, “Solprene 1205” is a block copolymer B (styrene polymer block)-[(styrene-butadiene) random copolymer block] diblock copolymer (trade name “Solprene 1205”, styrene Unit content 25% (of styrene units, 70% is present as styrene polymer block and 30% is present in (styrene-butadiene) random copolymer block) diblock copolymer, manufactured by Dinasol) “PW-90” represents a paraffinic process oil (trade name “Diana Process Oil PW-90”, manufactured by Idemitsu Kosan Co., Ltd.), and “EV-460” represents an ethylene vinyl acetate copolymer wax (trade name “ Evaflex EV-460 ", melting point 84 ° C, Mitsui DuPont Polychemical Co., Ltd.) The obtained hot melt adhesive composition was evaluated in the same manner as in Example 1. The results are shown in Table 3.

  Table 3 shows the following. That is, the hot melt adhesive composition of the present invention has both softener retention and die-cutting properties, and also has excellent retention and tackiness in a low temperature environment (implementation) Examples 1-6). On the other hand, the hot-melt adhesive composition not containing the block copolymer A used in the present invention is inferior in softener retention (Comparative Examples 1 to 3) and does not contain a wax. In this case, the holding power and the die cutting property are also inferior (comparison between Comparative Example 1 and Comparative Example 2). Moreover, even if it contains the block copolymer A used by this invention, the ratio for which the block copolymer A accounts with respect to the total weight of the block copolymer A and the block copolymer B is too small. The hot melt adhesive composition is inferior in holding power and softener holding ability (Comparative Example 4).

Claims (3)

A block copolymer A represented by the following general formula (A), and a block copolymer B having an aromatic vinyl polymer block and a conjugated diene polymer block as terminal blocks, A block copolymer component in which the ratio of the block copolymer A to the total weight of the copolymer A and the block copolymer B is 5 to 90% by weight, and is incompatible with the block copolymer component A hot melt adhesive composition comprising a wax, a softening agent compatible with a block copolymer component, and a tackifying resin.
Ar1-D-Ar2 (A)
(In the general formula (A), Ar1 represents an aromatic vinyl polymer block having a weight average molecular weight of 10,000 to 25,000, Ar2 represents an aromatic vinyl polymer block having a weight average molecular weight of 15,000 to 200,000, and D represents a conjugated diene. The ratio of the weight average molecular weight of the aromatic vinyl polymer block represented by Ar1 to the weight average molecule of the aromatic vinyl polymer block represented by Ar2 is 0.1 to 0.9. )   The wax content is 1 to 50 parts by weight, the softener content is 10 to 300 parts by weight, and the tackifier resin content is 10 to 500 parts by weight with respect to 100 parts by weight of the block copolymer component. The hot melt adhesive composition according to claim 1, which is a part.   The hot-melt adhesive composition according to claim 1 or 2, which is used as a label adhesive.