JP2020050762A - Pressure-sensitive adhesive composition and pressure-sensitive adhesive composition for label - Google Patents

Abstract

To provide a pressure-sensitive adhesive composition which exhibits good die-cutting performance when used for a label, and a pressure-sensitive adhesive composition for a label.SOLUTION: The pressure-sensitive adhesive composition containing a block copolymer composition and a hydrocarbon resin is provided in which: the block copolymer composition contains an aromatic vinyl-isoprene-aromatic vinyl triblock copolymer and an aromatic vinyl-isoprene diblock copolymer; a content of the aromatic vinyl monomer unit in the whole polymer components of the block copolymer composition is 10 to 30 mass%; the hydrocarbon resin contains an aliphatic monomer unit, or an aliphatic monomer unit and an aromatic monomer unit; a content of the aromatic monomer unit in the hydrocarbon resin is 40 mass% or less relative to the whole monomer units; and the hydrocarbon resin has a Z average molecular weight of 5,000 or more, a breaking strength of less than 6.0 MPa, and an elongation at break of less than 1,300%.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive composition for labels, and more particularly, to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive composition for labels which are excellent in die-cut performance when used for labels.

  In recent years, from the viewpoints of environmental problems, energy saving, resource saving, and the like, pressure-sensitive adhesive compositions that can be subjected to hot melt processing without using a solvent have been recommended. As an elastomer used for such a pressure-sensitive adhesive composition, styrene-isoprene- Styrene block copolymers are widely used.

  Pressure-sensitive adhesive compositions are required to have pressure-sensitive adhesive properties such as initial adhesive strength, peel adhesive strength, and holding power. Various studies have been made for the purpose of improving the adhesive performance.

For example, Patent Literature 1 discloses a block copolymer containing an aromatic vinyl-isoprene-aromatic vinyl triblock copolymer (A) and an aromatic vinyl-isoprene diblock copolymer (B). A coalescing composition,
(I) The ratio (Mw _Da / Mw) of the weight average molecular weight Mw _{Da of the} polyisoprene block of the triblock copolymer (A) to the weight average molecular weight Mw _Db of the polyisoprene block of the diblock copolymer (B). _Db ) is 0.5 or more and less than 1;
(Ii) the ratio of the aromatic vinyl monomer unit to the entire polymer component contained is 10 to 30% by mass,
(Iii) A pressure-sensitive adhesive composition comprising a block copolymer composition and a tackifier resin, wherein the composition has a breaking strength of less than 8 MPa and a breaking elongation of less than 1100%.

International Publication No. WO 2016/052310

  However, conventional pressure-sensitive adhesive compositions still have room for improvement in die-cut performance.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a pressure-sensitive adhesive composition and a pressure-sensitive adhesive composition for labels which are excellent in die-cut performance when used for labels.

  The present inventors have studied to achieve the above object, a triblock copolymer and a block copolymer composition containing a diblock copolymer and a composition containing a hydrocarbon resin, Content of aromatic vinyl monomer unit in block copolymer composition, content of aliphatic monomer unit and aromatic monomer unit in hydrocarbon resin, and Z-average molecular weight of hydrocarbon resin Was adjusted appropriately, and the breaking strength and the breaking elongation were adjusted appropriately, it was found that a label obtained using such a composition had excellent die-cut performance, and the present invention was completed.

  That is, according to the present invention, there is provided a pressure-sensitive adhesive composition containing a block copolymer composition and a hydrocarbon resin, wherein the block copolymer composition comprises an aromatic vinyl-isoprene-aromatic vinyl triblock copolymer. It contains a polymer and an aromatic vinyl-isoprene diblock copolymer, and the content of the aromatic vinyl monomer unit in the whole polymer component in the block copolymer composition is 10 to 30% by mass. Wherein the hydrocarbon resin contains an aliphatic monomer unit, or an aliphatic monomer unit and an aromatic monomer unit, and contains the aromatic monomer unit in the hydrocarbon resin. The amount is 40% by mass or less based on all monomer units, the Z-average molecular weight of the hydrocarbon resin is 5,000 or more, the breaking strength is less than 6.0 MPa, and the breaking elongation is less than 1,300%. Is an adhesive Forming material is provided.

In the pressure-sensitive adhesive composition of the present invention, the hydrocarbon resin preferably has a weight average molecular weight of 2,500 or more and a softening point of 90 ° C. or more.
In the pressure-sensitive adhesive composition of the present invention, the triblock copolymer is
Formula ^{(A): Ar1 a -D a} -Ar2 a
(Wherein, Ar @ 1 ^a is a poly vinyl aromatic block having a weight average molecular weight of 5,000 to 20,000, Ar @ 2 ^a is a poly vinyl aromatic block having a weight average molecular weight of 25,000~400,000, ^{D a} Represents a polyisoprene block).
In the pressure-sensitive adhesive composition of the present invention, the content of the hydrocarbon resin is preferably 10 to 500 parts by mass based on 100 parts by mass of the block copolymer composition.

  Further, according to the present invention, there is provided a pressure-sensitive adhesive composition for labels comprising the above-mentioned pressure-sensitive adhesive composition.

  According to the present invention, it is possible to provide a pressure-sensitive adhesive composition and a label pressure-sensitive adhesive composition that are excellent in die-cut performance when used for a label.

  The pressure-sensitive adhesive composition of the present invention contains a specific block copolymer composition and a specific hydrocarbon resin, and has a breaking strength of less than 6.0 MPa and a breaking elongation of less than 1300%. Since the pressure-sensitive adhesive composition of the present invention has such a configuration, a pressure-sensitive adhesive layer of a label can be formed, and the obtained label has an initial adhesive strength, an adhesive performance such as a peeling adhesive strength and a holding power. And die cutting performance. That is, the label obtained by using the pressure-sensitive adhesive composition of the present invention, even when cut with a die cutter, the pressure-sensitive adhesive layer does not pull the thread, the pressure-sensitive adhesive composition does not adhere to the knife provided with the die cutter. , Can be easily cut.

  The breaking strength of the pressure-sensitive adhesive composition of the present invention is less than 6.0 MPa, and more excellent die-cut performance is obtained. Therefore, it is preferably less than 5.5 MPa, more preferably less than 5.0 MPa, and the lower limit. Is not particularly limited.

  In the present invention, the breaking strength is measured by a method according to JIS K6251 using a 1 mm thick sheet obtained from the pressure-sensitive adhesive composition.

  The elongation at break of the pressure-sensitive adhesive composition of the present invention is less than 1,300%, and more preferably less than 1,200%, more preferably less than 1,100%, since more excellent die-cut performance is obtained. Yes, the lower limit is not particularly limited, but may be 100% or more.

  In the present invention, the elongation at break is measured by a method according to JIS K6251 using a 1 mm thick sheet obtained from the pressure-sensitive adhesive composition.

<Block copolymer composition>
The block copolymer composition contained in the pressure-sensitive adhesive composition of the present invention includes an aromatic vinyl-isoprene-aromatic vinyl triblock copolymer (hereinafter, sometimes simply referred to as “triblock copolymer”), And an aromatic vinyl-isoprene diblock copolymer (hereinafter sometimes simply referred to as “diblock copolymer”).

  In the block copolymer composition, the mass ratio of the triblock copolymer to the diblock copolymer (triblock copolymer / diblock copolymer) is preferable because more excellent die-cut performance is obtained. Is 10/90 to 70/30, more preferably 15/85 to 60/40.

  The content of the aromatic vinyl monomer unit in the entire polymer component in the block copolymer composition is 10 to 30% by mass, and more preferably 12 to 30%, since more excellent die-cut performance can be obtained. %, More preferably 15 to 28% by mass.

  The weight average molecular weight of the block copolymer composition is not particularly limited, but is preferably 70,000 to 300,000, and more preferably 85,000, since more excellent die-cut performance is obtained. ２270,000, more preferably 100,000 to 250,000.

  The molecular weight distribution represented by the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the block copolymer composition is not particularly limited, but is preferably 1. 01-10, more preferably 1.01-5, and even more preferably 1.01-3.

  The aromatic vinyl-isoprene-aromatic vinyl triblock copolymer is a triblock copolymer consisting of [polyaromatic vinyl block]-[polyisoprene block]-[polyaromatic vinyl block].

  The polyaromatic vinyl block of the triblock copolymer (hereinafter sometimes referred to as “polyaromatic vinyl block (Ar)”) is an aromatic vinyl monomer unit in the polymer chain of the triblock copolymer. Refers to a portion containing as a main structural unit.

  In the polyaromatic vinyl block (Ar), the content of the aromatic vinyl monomer unit is preferably 80% by mass or more, and more preferably 100% by mass. If the content of the aromatic vinyl monomer unit in the polyaromatic vinyl block (Ar) is too small, the resulting pressure-sensitive adhesive composition may have poor adhesion performance.

  As the aromatic vinyl monomer for obtaining the polyaromatic vinyl block (Ar), styrene; α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, Alkyl-substituted styrenes such as ethylstyrene and p-tert-butylstyrene; halogen-substituted styrenes such as 4-chlorostyrene, 2-bromostyrene and 3,5-difluorostyrene; 4-methoxystyrene, 3,5-dimethoxystyrene Alkoxy-substituted styrenes, etc .; Among these, styrene and alkyl-substituted styrene are preferable, and styrene is particularly preferable, from the viewpoints of excellent adhesive performance, die-cut performance, and availability.

The polyaromatic vinyl block (Ar) may be an aromatic vinyl monomer and another monomer copolymerizable with the aromatic vinyl monomer as long as the effects of the present invention are not substantially impaired. May be obtained by copolymerizing
Specific examples of other monomers copolymerizable with the aromatic vinyl monomer include conjugates such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. Diene monomers are exemplified.

  The weight average molecular weight of the polyaromatic vinyl block (Ar) is preferably from 5,000 to 390,000, more preferably from 6,000 to 380,000, and particularly preferably from 7,000 to 370,000. If the weight average molecular weight of the polyaromatic vinyl block (Ar) is too small, the resulting pressure-sensitive adhesive composition may have poor adhesion performance, while if too large, the melt viscosity of the pressure-sensitive adhesive composition may increase, and May be difficult.

  The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polyaromatic vinyl block (Ar) is preferably 2 or less, more preferably 1.5 or less. When this ratio is small, a pressure-sensitive adhesive composition having more excellent pressure-sensitive adhesive performance can be obtained.

  The content of the aromatic vinyl monomer unit in the entire triblock copolymer is usually 15 to 75% by mass, preferably 17 to 60% by mass, and more preferably 20 to 50% by mass. When the content of the aromatic vinyl monomer unit is in such a range, a pressure-sensitive adhesive composition having excellent pressure-sensitive adhesive performance and die-cut performance can be efficiently obtained.

  The triblock copolymer has two polyaromatic vinyl blocks as polyaromatic vinyl blocks (Ar), but they may be the same or different. .

  The polyisoprene block (hereinafter sometimes referred to as “polyisoprene block (D)”) of the triblock copolymer is a portion of the polymer chain of the triblock copolymer that contains an isoprene unit as a main constituent unit. Say. In the polyisoprene block, the content of the isoprene unit is preferably 80% by mass or more, and more preferably 100% by mass. If the content of the isoprene unit is too small, the resulting pressure-sensitive adhesive composition may have poor adhesion performance.

  The polyisoprene block (D) may be one obtained by copolymerizing isoprene and another monomer copolymerizable with isoprene as long as the effect of the present invention is not substantially impaired. Good. Specific examples of other monomers copolymerizable with isoprene include the above-mentioned aromatic vinyl monomers; 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and the like. And conjugated diene monomers other than isoprene.

  The weight average molecular weight of the polyisoprene block (D) is preferably from 20,000 to 400,000, more preferably from 30,000 to 270,000, and particularly preferably from 35,000 to 250,000. If the weight average molecular weight of the polyisoprene block (D) is too small, the adhesive performance of the resulting pressure-sensitive adhesive composition may be poor. On the other hand, if the weight-average molecular weight is too large, the melt viscosity of the pressure-sensitive adhesive composition increases, making handling difficult. There is a possibility that.

  The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polyisoprene block (D) is preferably 2 or less, more preferably 1.5 or less. When this ratio is small, a pressure-sensitive adhesive composition having more excellent pressure-sensitive adhesive performance can be obtained.

In the polyisoprene block (D), the proportion (vinyl bond content) of the isoprene units having a vinyl bond (—CH ＝ CH ₂ ) is not particularly limited. Usually, it is 50% by mass or less, preferably 20% by mass or less, more preferably 5 to 10% by mass. Within this range, a pressure-sensitive adhesive composition having more excellent pressure-sensitive adhesive properties can be obtained.

  The weight average molecular weight of the triblock copolymer is usually from 80,000 to 450,000, preferably from 100,000 to 250,000, more preferably from 110,000 to 230,000, particularly preferably from 120,000 to 220,000. 000. If the weight average molecular weight is too small, the resulting pressure-sensitive adhesive composition may have poor adhesive performance, and if it is too large, its melt viscosity may be high and handling may be difficult.

  The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the triblock copolymer is preferably 2 or less, more preferably 1.5 or less. When this ratio is small, a pressure-sensitive adhesive composition having more excellent pressure-sensitive adhesive performance can be obtained.

  As the triblock copolymer, more excellent die-cut performance can be obtained, so that the triblock copolymer A represented by the following general formula (A) and the triblock copolymer represented by the following general formula (B) Copolymer B is preferred, and triblock copolymer A is more preferred.

Formula ^{(A): Ar1 a -D a} -Ar2 a
(Wherein, Ar @ 1 ^a is a poly vinyl aromatic block having a weight average molecular weight of 5,000 to 20,000, Ar @ 2 ^a is a poly vinyl aromatic block having a weight average molecular weight of 25,000~400,000, ^{D a} Represents a polyisoprene block)

General formula (B): (Ar ^b -D ^b ) ₂ -X
(Ar ^b is a polyaromatic vinyl block having a weight average molecular weight of 5,000 to 100,000, D ^b is a polyisoprene block, and X represents a single bond or a residue of a coupling agent)

In the triblock copolymer A, the polyaromatic vinyl block (Ar1 ^a ) and the polyaromatic vinyl block (Ar2 ^a ) mainly include an aromatic vinyl monomer unit obtained by polymerizing an aromatic vinyl monomer. It is a polymer block configured as a repeating unit.

The aromatic vinyl monomer used to constitute the aromatic vinyl monomer unit of the polyaromatic vinyl block (Ar1 ^a ) and the polyaromatic vinyl block (Ar2 ^a ) is particularly an aromatic vinyl compound. Although not limited, for example, the same as the above-described polyaromatic vinyl block (Ar) can be used.

The polyaromatic vinyl block (Ar1 ^a ) and the polyaromatic vinyl block (Ar2 ^a ) may contain other monomer units as long as the aromatic vinyl monomer unit is the main repeating unit. Examples of the monomer constituting the monomer unit other than the aromatic vinyl monomer unit include the same as the above-described polyaromatic vinyl block (Ar), and the content thereof is also the same. do it. Further, the polyaromatic vinyl block (Ar1 ^a ) and the polyaromatic vinyl block (Ar2 ^a ) are preferably substantially composed of only one or two or more aromatic vinyl monomer units. And styrene units.

In the block copolymer A, the polyaromatic vinyl block (Ar1 ^a ) and the polyaromatic vinyl block (Ar2 ^a ) have different weight average molecular weights. When the pressure-sensitive adhesive composition of the present invention contains such an asymmetric block copolymer A, the pressure-sensitive adhesive composition of the present invention is more excellent in die-cut performance.

The weight average molecular weight of the polyaromatic vinyl block (Ar1 ^a ) is from 5,000 to 20,000, more preferably from 10,000 to 20,000, and still more preferably from 11,000 to 18,000. .

The weight average molecular weight of the polyaromatic vinyl block (Ar @ 2 ^a) is a 25,000～400,000, more preferably 25,000～300,000, even more preferably at 27,000～200,000 .

The ratio of the weight average molecular weight of the polyaromatic vinyl block (Ar @ 1 ^a) and polyaromatic vinyl block ^{(Ar2 a) ((Ar1 a} ) :( Ar2 a)) is preferably 1: 1 to 1: Yes 15 , More preferably 1: 2 to 1:10.

The polyisoprene block (D ^a ) is a polymer block composed mainly of isoprene units obtained by polymerizing isoprene.

Further, the polyisoprene block (D ^a ) may contain other monomer units as long as the isoprene unit is a main repeating unit, and the monomer constituting the monomer unit other than the isoprene unit may be used. Examples thereof include those similar to the polyisoprene block (D), and the content thereof and the vinyl bond content may be the same. Further, it is particularly preferable that the polyisoprene block (D ^a ) is composed of only an isoprene unit.

The weight average molecular weight of the polyisoprene block (D ^a ) is preferably from 20,000 to 400,000, more preferably from 30,000 to 170,000, and still more preferably from 35,000 to 150,000. .

  The weight average molecular weight of the block copolymer A (that is, the weight average molecular weight of the entire block copolymer A) is preferably from 80,000 to 300,000, more preferably from 100,000 to 270,000, More preferably, it is 120,000-250,000.

  The content of the aromatic vinyl monomer unit of the block copolymer A is preferably 20 to 60% by mass, and more preferably 25 to 60% by mass, based on all the monomer units constituting the block copolymer A. It is 60% by mass, and more preferably 30 to 50% by mass.

  The block copolymer A is preferably obtained by a production method in which an aromatic vinyl monomer, isoprene, and then an aromatic vinyl monomer are sequentially polymerized in this order to form a polymer block. Therefore, it is preferable that the block copolymer A does not contain a residue of a coupling agent. Details of such a manufacturing method will be described later.

The triblock copolymer B is a copolymer represented by the following general formula (B).
General formula (B): (Ar ^b -D ^b ) ₂ -X
(Ar ^b is a polyaromatic vinyl block having a weight average molecular weight of 5,000 to 100,000, D ^b is a polyisoprene block, and X represents a single bond or a residue of a coupling agent)

The block copolymer B has a structure in which two diblocks (Ar ^b -D ^b ) are bonded to each other directly by a single bond or via a residue (X) of a coupling agent. The residue (X) of the coupling agent is not particularly limited as long as it is a divalent residue of the coupling agent, but is preferably a residue of a silicon atom-containing coupling agent, and is preferably a residue of a halogenated silane or an alkoxysilane. More preferably, it is a residue. Examples of the coupling agent constituting the residue of the coupling agent include those described below.

The polyaromatic vinyl block (Ar ^b ) is a polymer block composed mainly of an aromatic vinyl monomer unit obtained by polymerizing an aromatic vinyl monomer.

The aromatic vinyl monomer used to constitute the aromatic vinyl monomer unit of the polyaromatic vinyl block (Ar ^b ) is not particularly limited as long as it is an aromatic vinyl compound. And the same as those of the aromatic group vinyl block (Ar).

The polyaromatic vinyl block (Ar ^b ) may contain other monomer units as long as the aromatic vinyl monomer unit is the main repeating unit, and may contain other monomer units than the aromatic vinyl monomer unit. Examples of the monomer constituting the monomer unit include those similar to the above-mentioned polyaromatic vinyl block (Ar), and the content thereof may be the same. Further, each polyaromatic vinyl block in the block copolymer B may be composed of the same aromatic vinyl monomer unit, or may be composed of different aromatic vinyl monomer units. Also, the polyaromatic vinyl block (Ar ^b ) is preferably substantially composed of only one or two or more aromatic vinyl monomer units, and preferably composed of only styrene units. Is particularly preferred.

The weight average molecular weight of the polyaromatic vinyl block (Ar ^b ) is preferably 5,000 to 100,000, more preferably 6,000 to 80,000, further preferably 7,000 to 70,000, and particularly preferably. It is in the range of 7,000 to 20,000.

As long as the weight average molecular weights of the two polyaromatic vinyl blocks (Ar ^b ) of the block copolymer B are within the above range, they may be the same or different from each other. , Are preferably substantially equal.

The polyisoprene block (D ^b ) is a polymer block composed mainly of isoprene units obtained by polymerizing polyisoprene.

Further, the polyisoprene block (D ^b ) may contain other monomer units as long as the isoprene unit is the main repeating unit, and the monomer constituting the monomer unit other than the isoprene unit Examples thereof include those similar to the polyisoprene block (D), and the content thereof and the vinyl bond content may be the same. Further, it is particularly preferable that the polyisoprene block (D ^b ) is composed of only an isoprene unit.

The weight average molecular weight of the polyisoprene blocks ^{(D b)} is preferably 20,000～400,000, more preferably 30,000～170,000, even more preferably at 35,000～150,000 .

The weight average molecular weights of the two polyisoprene blocks (D ^b ) of the block copolymer B may be the same or different from each other as long as they are within the above range. It is preferable that they are equal to each other.

  The weight average molecular weight of the block copolymer B (that is, the weight average molecular weight of the entire block copolymer B) is preferably from 80,000 to 450,000, more preferably from 100,000 to 270,000, More preferably, it is 120,000-250,000.

  The content of the aromatic vinyl monomer unit of the block copolymer B is preferably 20 to 60% by mass, more preferably 25 to 60% by mass, based on all the monomer units constituting the block copolymer B. It is 60% by mass, and more preferably 30 to 50% by mass.

  The content of the triblock copolymer in the block copolymer composition is usually 10 to 90% by mass, preferably 15 to 85% by mass, and more preferably 20 to 80% by mass. If this ratio is too small, the adhesive performance of the obtained pressure-sensitive adhesive composition will be poor, and if it is too high, the initial adhesive strength and die-cut performance of the pressure-sensitive adhesive composition will tend to be poor.

  The aromatic vinyl-isoprene diblock copolymer contained in the pressure-sensitive adhesive composition of the present invention is a diblock copolymer consisting of [polyaromatic vinyl block]-[polyisoprene block].

Polyaromatic vinyl block diblock copolymer has (hereinafter sometimes referred to as "poly vinyl aromatic block (Ar ^c)".), In the polymer chain of the diblock copolymer, the aromatic vinyl monomer A part containing a unit as a main constituent unit.

In the polyaromatic vinyl block (Ar ^c ), the aromatic vinyl monomer unit content is preferably 80% by mass or more, more preferably 100% by mass. If the content of the aromatic vinyl monomer unit in the polyaromatic vinyl block is too small, the resulting pressure-sensitive adhesive composition may have poor adhesion performance.

As the aromatic vinyl monomer for obtaining the polyaromatic vinyl block (Ar ^c ), the same as those listed as the aromatic vinyl monomer for obtaining the polyaromatic vinyl block (Ar) Is mentioned. Of these, styrene and alkyl-substituted styrene are preferred, and styrene is particularly preferred.

The polyaromatic vinyl block (Ar ^c ) is an aromatic vinyl monomer and another monomer copolymerizable with the aromatic vinyl monomer as long as the effects of the present invention are not substantially impaired. May be obtained by copolymerizing
Other monomers copolymerizable with the aromatic vinyl monomer include conjugated diene monomers such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene and 1,3-pentadiene. Body.

The weight average molecular weight of the polyaromatic vinyl block (Ar ^c) is 5,000 to 20,000, more preferably from 10,000 to 20,000, even more preferably at 11,000～18,000 . If the weight average molecular weight of the polyaromatic vinyl block (Ar ^c ) is too small, the adhesive performance of the resulting pressure-sensitive adhesive composition may be poor. Conversely, if it is too large, the melt viscosity of the pressure-sensitive adhesive composition may increase, and May be difficult.

The weight average molecular weight of the polyaromatic vinyl block (Ar ^c) (Mw) and number average molecular weight (Mn) ratio of (Mw / Mn) is preferably 2 or less, more not more than 1.5 preferable. When this ratio is small, a pressure-sensitive adhesive composition having more excellent pressure-sensitive adhesive performance can be obtained.

The polyisoprene block (hereinafter sometimes referred to as “polyisoprene block (D ^c )”) of the diblock copolymer is a portion containing an isoprene unit as a main constituent unit in the polymer chain of the diblock copolymer. Say.
In the polyisoprene block (D ^c ), the content of the isoprene unit is preferably 80% by mass or more, more preferably 100% by mass. If the isoprene unit content is too small, the resulting pressure-sensitive adhesive composition may have poor initial adhesion at low temperatures.

The polyisoprene block (D ^c ) may be a copolymer of isoprene and another monomer copolymerizable with isoprene as long as the effects of the present invention are not substantially impaired. Other monomers copolymerizable with isoprene include the above-mentioned aromatic vinyl monomers; other than isoprene such as 1,3-butadiene, 2,3-dimethyl-1,3-butadiene and 1,3-pentadiene. A conjugated diene monomer;

The weight average molecular weight of the polyisoprene block (D ^c ) is preferably from 20,000 to 400,000, more preferably from 30,000 to 170,000, and still more preferably from 35,000 to 150,000. . If the weight average molecular weight of the polyisoprene block (D ^c ) is too small, the adhesive performance of the resulting pressure-sensitive adhesive composition may be inferior. If too large, the melt viscosity of the pressure-sensitive adhesive composition increases, and handling becomes difficult. This can be difficult.

The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polyisoprene block (D ^c ) is preferably 2 or less, more preferably 1.5 or less. When this ratio is small, a pressure-sensitive adhesive composition having more excellent pressure-sensitive adhesive performance can be obtained.

  The content of the aromatic vinyl monomer unit in the entire diblock copolymer is usually 8 to 50% by mass, preferably 10 to 40% by mass, and more preferably 12 to 30% by mass. When the content of the aromatic vinyl monomer unit is too small, the adhesive performance of the obtained pressure-sensitive adhesive composition may be poor. On the contrary, when the content is too large, the initial adhesive strength of the pressure-sensitive adhesive composition at low temperature is poor. There are cases.

Among the isoprene units in the diblock copolymer, the proportion (vinyl bond content) of those having a vinyl bond (—CH ＝ CH ₂ ) is not particularly limited, and is usually 50% by mass or less, preferably 20% by mass. %, More preferably 5 to 10% by mass. Within this range, a pressure-sensitive adhesive composition having excellent initial adhesive strength at low temperatures can be obtained.

  The weight average molecular weight of the diblock copolymer is usually 80,000 to 200,000, preferably 90,000 to 180,000, more preferably 100,000 to 160,000, and particularly preferably 110,000 to 140. , 000. If the weight average molecular weight is too small, the resulting pressure-sensitive adhesive composition tends to have poor adhesive performance, while if it is too high, the melt viscosity of the pressure-sensitive adhesive composition increases, which may make handling difficult.

  The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the diblock copolymer is preferably 2 or less, more preferably 1.5 or less. When this ratio is small, a pressure-sensitive adhesive composition having excellent pressure-sensitive adhesive performance can be efficiently obtained.

The content of the diblock copolymer in the block copolymer composition is usually 10 to 90% by mass, preferably 15 to 85% by mass, and more preferably 20 to 80% by mass.
When the content of the diblock copolymer is in such a range, a pressure-sensitive adhesive composition having more excellent pressure-sensitive adhesive performance and die-cut performance can be obtained.

  In the block copolymer composition, since the effects of the present invention are well expressed in a well-balanced manner, the weight average molecular weight of the triblock copolymer is 120,000 to 250,000, and the diblock copolymer It is preferred that the weight average molecular weight of the union is from 80,000 to 140,000.

  In the block copolymer composition, the ratio of the content of the aromatic vinyl monomer unit of the triblock copolymer to the content of the aromatic vinyl monomer unit of the diblock copolymer is 1. It is preferably at least 5, more preferably at least 1.6, even more preferably from 1.7 to 4.0.

  The method for producing the triblock copolymer is not particularly limited, and a conventionally known production method can be employed. For example, by anionic living polymerization, a method of sequentially polymerizing a polyaromatic vinyl block and a polyisoprene block, and a method of producing a block copolymer having an active terminal having a living property, respectively, and those described later. A method of reacting with a coupling agent and producing by coupling can be adopted.

  The method for producing the diblock copolymer is not particularly limited, and a conventionally known production method can be employed. For example, a method of sequentially polymerizing a polyaromatic vinyl block and a polyisoprene block by an anionic living polymerization method can be adopted.

  Further, the triblock copolymer and the diblock copolymer may be separately produced as described above, but as described below, the respective polymerization steps are combined into one, and the anion living polymerization method is used. And a mixture of a triblock copolymer and a diblock copolymer. As such a manufacturing method, a first manufacturing method and a second manufacturing method will be exemplified.

The first manufacturing method includes the following first to fifth steps.
(First Step) In a polymerization solvent, an aromatic vinyl monomer is polymerized using an anionic polymerization initiator to generate a polyaromatic vinyl block chain having an active terminal having a living property.
(Second step) Isoprene is polymerized from a living active end of a polyaromatic vinyl block chain to obtain an aromatic vinyl-isoprene diblock block having a living active end.
(Third Step) A part of the living terminal of the aromatic vinyl-isoprene diblock chain is deactivated by a polymerization terminator to obtain an aromatic vinyl-isoprene diblock copolymer. At this time, the amount of the polymerization terminator is adjusted to be less than 1 molar equivalent with respect to the active terminal of the aromatic vinyl-isoprene diblock chain.
(Fourth step) The aromatic vinyl monomer is added to the solution obtained in the above (third step), and the remaining living activity of the aromatic vinyl-isoprene diblock chain having an active terminal having a living property is obtained. The terminal is reacted with the aromatic vinyl monomer to obtain an aromatic vinyl-isoprene-aromatic vinyl triblock chain having an active terminal having a living property.
(Fifth step) The living terminal of the aromatic vinyl-isoprene-aromatic vinyl triblock chain is deactivated with a polymerization terminator to obtain an aromatic vinyl-isoprene-aromatic vinyl triblock copolymer. .

The second manufacturing method includes the following first and second steps and sixth and seventh steps, for a total of four steps.
(First Step) In a polymerization solvent, an aromatic vinyl monomer is polymerized using an anionic polymerization initiator to generate a polyaromatic vinyl block chain having an active terminal having a living property.
(Second step) Isoprene is polymerized from a living active end of a polyaromatic vinyl block chain to obtain an aromatic vinyl-isoprene diblock block having a living active end.
(Sixth step) A part of an aromatic vinyl-isoprene diblock chain having an active terminal having a living property is reacted with a coupling agent, and the coupled aromatic vinyl-isoprene-aromatic vinyl triblock copolymer is reacted. Get united. At this time, the amount of the reactive group of the coupling agent is adjusted to be less than 1 molar equivalent with respect to the active terminal of the aromatic vinyl-isoprene diblock chain.
(Seventh Step) The living terminal of the aromatic vinyl-isoprene diblock block is deactivated by a polymerization terminator to obtain an aromatic vinyl-isoprene diblock copolymer.

Hereinafter, each of these steps will be described in order.
In the first step of the first production method, an aromatic vinyl monomer is polymerized in a polymerization solvent using an anionic polymerization initiator to form a polyaromatic vinyl block chain having a living active end. This is the step of causing

The polymerization solvent used 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 can be used.
Examples of the chain hydrocarbon solvent include n-butane, isobutane, n-hexane, 1-butene, isobutylene, trans-2-butene, cis-2-butene, 1-pentene, trans-2-pentene, and cis-2- Examples thereof include pentene, n-pentane, trans-2-pentane, neopentane, and mixtures thereof.
Examples of the cyclic hydrocarbon solvent include benzene, toluene, xylene, cyclohexane and the like.
Among these, it is preferable to use a mixture of a chain hydrocarbon solvent and a cyclic hydrocarbon solvent because it is easy to control the polymerization temperature and the molecular weight of the polymer.
When a chain hydrocarbon solvent and a cyclic hydrocarbon solvent are used as a mixture, the mixing ratio is a mass ratio of (chain hydrocarbon solvent) :( cyclic hydrocarbon solvent), preferably from 5:95 to The ratio is 50:50, more preferably 10:90 to 40:60.

  The amount of the polymerization solvent used is generally 100 to 1000 parts by mass, preferably 150 to 400 parts by mass, per 100 parts by mass of the total monomers used, in the total of the first to fourth steps.

  The anionic polymerization initiator is not particularly limited, and is not particularly limited as long as it is used for anionic polymerization of an aromatic vinyl monomer and isoprene, and a known one can be used. Specific examples thereof include organic lithium initiators such as methyllithium, n-propyllithium, n-butyllithium, and sec-butyllithium. Among these, n-butyllithium is preferred. The amount of the polymerization initiator to be used may be appropriately determined based on a conventional method so that a polymer having a desired weight average molecular weight is obtained.

Further, it is preferable to carry out the polymerization in the presence of a polar compound because the polymerization rate is adjusted and a polymer having a narrow molecular weight distribution is easily produced.
The polar compound is a compound whose molecule has electric polarity, and specifically, a compound whose relative dielectric constant measured at 25 ° C. is preferably 2.5 to 5.0.
Examples of the polar compound include aromatic ethers such as diphenyl ether and anisole; aliphatic ethers such as diethyl ether and dibutyl ether; tertiary monoamines such as trimethylamine, triethylamine and tripropylamine; N, N, N ', N'- Tertiary polyamines such as tetramethylethylenediamine and N, N, N ', N'-tetraethylethylenediamine; and the like. Of these, N, N, N ', N'-tetramethylethylenediamine is preferred.

  The amount of the polar compound used is preferably 0.05 to 0.5 mol, more preferably 0.01 to 0.1 mol, per 1 mol of the anionic polymerization initiator.

The second step is a step of polymerizing isoprene from a living active end of the polyaromatic vinyl block chain to obtain an aromatic vinyl-isoprene diblock chain having a living active end.
In the second step, isoprene is preferably reacted while being continuously added in order to suppress rapid generation of reaction heat.

  The third step is a step of inactivating a part of the living terminal of the aromatic vinyl-isoprene diblock chain with a polymerization terminator to obtain an aromatic vinyl-isoprene diblock copolymer.

  The polymerization terminator is not particularly limited as long as it can react with the active terminal to deactivate the active terminal and does not react with another active terminal after reacting with one active terminal. From the viewpoint of suppressing moisture absorption, a polymerization terminator that is a compound containing no halogen atom is preferable, and among these, a metal alkoxide, a metal aryl oxide, or a metal hydroxide is generated when reacted with an active terminal. The polymerization terminator used is particularly preferred. Compounds particularly preferably used as the polymerization terminator include water, monohydric alcohols such as methanol and ethanol, and monohydric phenols such as phenol and cresol.

  The amount of the polymerization terminator to be used is determined according to the mass ratio of the triblock copolymer and the diblock copolymer, and is particularly an amount that is less than 1 molar equivalent with respect to the active terminal of the triblock chain. Although not limited, usually, the polymerization terminator is in the range of 0.18 to 0.91 molar equivalent, preferably 0.35 to 0.80 molar equivalent, based on the active terminal.

In the fourth step, an aromatic vinyl monomer is added to the solution obtained in the above (third step), and the remaining living activity of the aromatic vinyl-isoprene diblock chain having a living active terminal is removed. This is a step of reacting the terminal with the aromatic vinyl monomer.
When the aromatic vinyl monomer is added, the aromatic vinyl chain extends from the terminal of the aromatic vinyl-isoprene diblock chain having an active terminal which has not reacted with the polymerization terminator. At this time, when an aromatic vinyl chain having a weight average molecular weight larger than that of the aromatic vinyl chain in the aromatic vinyl-isoprene diblock chain is formed, finally, in the fifth step, the triblock copolymer described above is finally obtained. Combined A is obtained. Further, when an aromatic vinyl chain having a weight average molecular weight equivalent to that of the aromatic vinyl chain in the aromatic vinyl-isoprene diblock chain is formed, finally in the fifth step, the above-mentioned triblock copolymer is obtained. B is obtained.

  Next, a second manufacturing method will be described. The first and second steps in the second manufacturing method are as described in the first manufacturing method.

  In the second manufacturing method, a sixth step is performed after the second step. In the sixth step, a part of an aromatic vinyl-isoprene diblock chain having an active terminal having a living property is reacted with a coupling agent, and the coupled aromatic vinyl-isoprene-aromatic vinyl triblock copolymer is reacted. This is a step of obtaining a united state.

  The coupling agent is a compound that has two sites that react with the living active terminal of the polymer molecule and bond with the polymer molecule.

  Examples of the bifunctional coupling agent having two reaction sites include difunctional silanes such as dichlorosilane, monomethyldichlorosilane, and dimethyldichlorosilane; bifunctional alkoxysilanes such as diphenyldimethoxysilane and diphenyldiethoxysilane; Bifunctional halogenated alkanes such as dichloroethane, dibromoethane, methylene chloride and dibromomethane; difunctional tins such as dichlorotin, monomethyldichlorotin, dimethyldichlorotin, monoethyldichlorotin, diethyldichlorotin, monobutyldichlorotin and dibutyldichlorotin Benzoic acid, CO, 2-chloropropene and the like. Among them, dimethyldichlorosilane is preferable. The amount of the coupling agent used is such that the amount of the aromatic vinyl-isoprene-aromatic vinyl block copolymer (corresponding to the triblock copolymer (A)) obtained by coupling falls within a desired range. May be determined as appropriate.

  The seventh step is a step of inactivating the living terminal of the aromatic vinyl-isoprene diblock chain with a polymerization terminator to obtain an aromatic vinyl-isoprene diblock copolymer.

  As the polymerization terminator, those commonly used in anionic living polymerization can be used. Specific examples include water; alcohols such as methyl alcohol and ethyl alcohol; inorganic acids such as hydrochloric acid; organic acids such as acetic acid; monofunctional silane compounds such as chlorotrimethylsilane;

By the above method, a solution containing a mixture of the triblock copolymer and the diblock copolymer is obtained. An antioxidant may be added to this solution as needed.
Thereafter, the polymer is separated from the solution by a known polymer separation method such as steam stripping, and the obtained polymer is dried to obtain a mixture of a triblock copolymer and a diblock copolymer. .

When a mixture of a triblock copolymer and a diblock copolymer is produced by the above method, the proportion of the triblock copolymer to the total amount of the triblock copolymer and the diblock copolymer is usually 10%. ７０70 mass%, preferably 15-60 mass%. If this ratio is in this range, when producing the block copolymer composition, without adding a separately produced triblock copolymer, it is possible to obtain a block copolymer composition of a preferred composition Can be.
The proportion of the triblock copolymer to the total amount of the triblock copolymer and the diblock copolymer can be adjusted by the amount of the polymerization terminator used in the third step or the amount of the coupling agent used in the sixth step. .

  The method for producing the block copolymer composition is not particularly limited. For example, separately manufactured or obtained respectively, triblock copolymer, a method of kneading and manufacturing a diblock copolymer at a predetermined ratio, a triblock copolymer and a diblock copolymer at a predetermined ratio, respectively. Mixing in the form of a solution, a method of separating and drying the polymer by a known method, a method of manufacturing by drying, a mixture of the triblock copolymer and the diblock copolymer obtained by the above-described method as a polymer component as it is The method used can be adopted.

<Hydrocarbon resin>
The pressure-sensitive adhesive composition of the present invention contains a hydrocarbon resin in addition to the block copolymer composition. The hydrocarbon resin used in the present invention contains an aliphatic monomer unit, or contains an aliphatic monomer unit and an aromatic monomer unit. As the hydrocarbon resin used in the present invention, a hydrocarbon resin containing only an aliphatic monomer unit, and containing an aliphatic monomer unit and an aromatic monomer unit, an aromatic monomer unit At least one selected from the group consisting of hydrocarbon resins having a content of 40% by mass or less based on all monomer units is preferable.

  In the pressure-sensitive adhesive composition of the present invention, the hydrocarbon resin contains an aliphatic monomer unit, or contains an aliphatic monomer unit and a predetermined ratio of an aromatic monomer unit, and The one having a very limited Z-average molecular weight (Mz) is used. Due to such characteristics, the pressure-sensitive adhesive composition of the present invention is excellent in adhesive performance such as initial adhesive strength, peel adhesive strength and holding power, and is also excellent in die-cut performance.

  The aliphatic monomer unit may be any unit that does not contain an aromatic ring. For example, a 1,3-pentadiene monomer unit, an alicyclic monoolefin monomer unit having 4 to 6 carbon atoms, a carbon unit An acyclic monoolefin monomer unit and an alicyclic diolefin monomer unit of the formulas 4 to 8 are exemplified.

  The content ratio of the 1,3-pentadiene (piperylene) monomer unit in the hydrocarbon resin is preferably 1 to 80% by mass, more preferably 20 to 75% by mass, and still more preferably 30 to 70% by mass. . By setting the content ratio of the 1,3-pentadiene monomer unit in the above range, the obtained pressure-sensitive adhesive composition can have more excellent pressure-sensitive adhesive performance. The cis / trans isomer ratio in 1,3-pentadiene may be any ratio, and is not particularly limited.

  The alicyclic monoolefin having 4 to 6 carbon atoms for forming an alicyclic monoolefin monomer unit having 4 to 6 carbon atoms has one ethylenically unsaturated bond in its molecular structure and is non-aromatic. Any hydrocarbon compound having an acyclic ring structure and having 4 to 6 carbon atoms may be used, and is not particularly limited. Specific examples thereof include cyclobutene, cyclopentene, cyclohexene, methylcyclobutene, and methylcyclopentene. The hydrocarbon compound having 4 to 6 carbon atoms may be used alone or in combination of two or more, but preferably contains at least cyclopentene, and has 4 to 6 carbon atoms. The proportion of cyclopentene in the alicyclic monoolefin is preferably at least 50% by mass.

  The content of the alicyclic monoolefin monomer unit having 4 to 6 carbon atoms in the hydrocarbon resin is preferably 1 to 30% by mass, more preferably 5 to 30% by mass, and still more preferably 10 to 30% by mass. %. By setting the content of the alicyclic monoolefin monomer unit having 4 to 6 carbon atoms in the above range, the obtained pressure-sensitive adhesive composition can have more excellent pressure-sensitive adhesive performance.

  An acyclic monoolefin having 4 to 8 carbon atoms for forming an acyclic monoolefin monomer unit having 4 to 8 carbon atoms has one ethylenically unsaturated bond in its molecular structure; Any chain hydrocarbon compound having no ring structure and having 4 to 8 carbon atoms may be used, and is not particularly limited. Specific examples thereof include 1-butene, 2-butene, and isobutylene (2-methylpropene). Butenes; 1-pentene, 2-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene and other pentenes; 1-hexene, 2-hexene, 2- Hexenes such as methyl-1-pentene; heptene such as 1-heptene, 2-heptene and 2-methyl-1-hexene; 1-octene, 2-octene, 2-methyl-1-heptene, diisobutylene (2 , 4,4-g Methylpentene-1 and 2,4,4 -1) octenes and the like; and the like. The acyclic monoolefin having 4 to 8 carbon atoms may be used singly or in combination of two or more. At least 2-methyl-2-butene, isobutylene and diisobutylene may be used. It is preferable that at least one selected from the group be included, and the proportion of the total amount of 2-methyl-2-butene, isobutylene and diisobutylene in the alicyclic monoolefin having 4 to 6 carbon atoms be 50% by mass. More preferably, it is the above.

  The content of the acyclic monoolefin monomer unit having 4 to 8 carbon atoms in the hydrocarbon resin is preferably 0 to 50% by mass, more preferably 0 to 40% by mass, and still more preferably 5 to 30% by mass. %. By containing the acyclic monoolefin monomer unit having 4 to 8 carbon atoms in the above ratio, the obtained pressure-sensitive adhesive composition can have more excellent pressure-sensitive adhesive performance.

  The alicyclic diolefin for forming the alicyclic diolefin monomer unit is a hydrocarbon compound having two or more ethylenically unsaturated bonds and a non-aromatic ring structure in its molecular structure. There is no particular limitation, but specific examples thereof include multimers of cyclopentadiene such as cyclopentadiene and dicyclopentadiene, methylcyclopentadiene, and multimers of methylcyclopentadiene. The alicyclic diolefin may be used alone or in combination of two or more types. However, it is preferable that at least dicyclopentadiene is contained. More preferably, the proportion occupied by pentadiene is 50% by mass or more.

  The content of the aliphatic monomer unit in the hydrocarbon resin is preferably 60% by mass or more, more preferably 65% by mass or more, since more excellent die-cut performance is obtained. The content is more preferably 70% by mass or more, and the upper limit is not particularly limited, but may be 100% by mass or less, or may be 99% by mass or less.

  The aromatic monomer unit may preferably include an aromatic monoolefin monomer unit, an aromatic monomer unit having a structure in which two or more cyclic structures are bonded, and the like.

  The content of the aromatic monomer unit in the hydrocarbon resin is 40% by mass or less, preferably 35% by mass or less, and more preferably 30% by mass or less in order to obtain more excellent die-cut performance. Is preferably 0% by mass or more, and may be 1% by mass or more.

  Aromatic monoolefin for forming an aromatic monoolefin monomer unit is a hydrocarbon compound having one ethylenically unsaturated bond in its molecular structure and having an aromatic ring structure. Although not particularly limited, specific examples thereof include styrene, α-methylstyrene, and vinyltoluene. The aromatic monoolefin may be used alone or in combination of two or more, but preferably contains at least styrene, and the ratio of styrene in the aromatic monoolefin is 50%. It is more preferred that the content be at least mass%.

  The content ratio of the aromatic monoolefin monomer unit in the hydrocarbon resin is preferably 0 to 40% by mass, more preferably 0 to 35% by mass, and further preferably 0 to 30% by mass. By containing the aromatic monoolefin monomer unit in the above-described ratio, the obtained pressure-sensitive adhesive composition can have more excellent pressure-sensitive adhesive performance.

  An aromatic monomer having a structure in which two or more cyclic structures are bonded for forming an aromatic monomer unit having a structure in which two or more cyclic structures are bonded includes an aromatic ring structure, As long as it is a hydrocarbon compound having two or more ring structures, it is not particularly limited. Specific examples thereof include a compound having a naphthalene skeleton such as naphthalene, a compound having a fluorene skeleton such as fluorene, and a biphenyl skeleton such as biphenyl. Compounds having an anthracene skeleton such as anthracene; compounds having a phenanthrene skeleton such as phenanthrene; compounds having an indene skeleton such as indene; and compounds having a benzothiophene skeleton such as benzothiophene. As the aromatic monomer having a structure in which two or more cyclic structures are bonded, only one kind may be used, or two or more kinds may be used in combination.

  The content ratio of the aromatic monomer unit having a structure in which two or more cyclic structures are bonded in the hydrocarbon resin is preferably 0 to 50% by mass, more preferably 0 to 40% by mass, and further preferably 0 to 40% by mass. 30% by mass. By containing an aromatic monomer unit having a structure in which two or more cyclic structures are bonded in the above-described ratio, the obtained pressure-sensitive adhesive composition can have more excellent pressure-sensitive adhesive performance.

  Further, the hydrocarbon resin may contain a unit of another monomer other than the above-mentioned monomer unit. The other monomer is not particularly limited. For example, non-monomer other than 1,3-pentadiene such as 1,3-butadiene, 1,2-butadiene, isoprene, 1,3-hexadiene and 1,4-pentadiene may be used. Alicyclic monoolefins having 7 or more carbon atoms, such as cycloheptene; acyclic monoolefins having 4 to 8 carbon atoms other than carbon atoms, such as ethylene, propylene, and nonene; These may be used alone or in combination of two or more. The content ratio of the unit of the other monomer in the hydrocarbon resin is preferably 0 to 30% by mass, more preferably 0 to 25% by mass, and still more preferably 0 to 20% by mass.

  The weight average molecular weight (Mw) of the hydrocarbon resin is preferably 2,500 or more, more preferably 2,500 to 10,000, and still more preferably, in order to obtain more excellent die cut performance. It is in the range of 2,500 to 8,500, and more preferably in the range of 2,500 to 8,000.

  The Z-average molecular weight (Mz) of the hydrocarbon resin is in the range of 5,000 or more, and more preferably 6,000 to 100,000, and particularly preferably, in order to obtain more excellent die-cut performance. It is in the range of 7,000 to 50,000.

  Further, since the hydrocarbon resin can obtain more excellent die-cut performance, the ratio of the Z-average molecular weight to the weight-average molecular weight (Mz / Mw) is preferably in the range of 1.0 to 6.0, more preferably. Is in the range of 1.2 to 5.5, more preferably in the range of 1.4 to 5.0.

  The number average molecular weight (Mn) of the hydrocarbon resin is preferably in the range of 500 to 4,000, more preferably in the range of 750 to 3,500, and still more preferably, since more excellent die-cut performance is obtained. Ranges from 1,000 to 3,000.

  Further, since the hydrocarbon resin can obtain more excellent die-cut performance, the ratio of the number average molecular weight to the weight average molecular weight (Mw / Mn) is preferably in the range of 1.0 to 5.0, more preferably. Is in the range of 1.2 to 4.5, more preferably in the range of 1.4 to 4.0.

  In the present invention, the weight average molecular weight (Mw), the Z average molecular weight (Mz), and the number average molecular weight (Mn) of the hydrocarbon resin are determined as values in terms of polystyrene measured by high performance liquid chromatography. The weight average molecular weight (Mw), the Z average molecular weight (Mz), and the number average molecular weight (Mn) of the hydrocarbon resin are determined by adjusting the amount of each acyclic monoolefin having 4 to 8 carbon atoms. It can be controlled by adjusting the body composition or adjusting the production conditions such as the amount of the Lewis acid catalyst in the method for producing a hydrocarbon resin described below.

  The softening point of the hydrocarbon resin is preferably 90 ° C. or higher, more preferably 90 to 170 ° C., still more preferably 90 to 160 ° C., and particularly preferably 95 to 150 ° C., since more excellent die cutting performance can be obtained. It is. The softening point of the hydrocarbon resin can be controlled by adjusting the composition of each monomer, or by adjusting the production conditions in a method for producing a hydrocarbon resin described below.

  As a method for producing a hydrocarbon resin, a monomer mixture containing each of the above-mentioned monomers is subjected to addition polymerization to obtain a content of an aliphatic monomer unit and an aromatic monomer unit and a Z average molecular weight (Mz ) Is not particularly limited as long as it is capable of obtaining a hydrocarbon resin as in the above range. For example, it can be produced by addition polymerization using a Friedel-Crafts type cationic polymerization catalyst. A method based on addition polymerization using a Lewis acid catalyst (A) is preferred.

The Lewis acid catalyst (A) is not particularly limited, but preferably comprises a metal halide, and is preferably a halide of an element belonging to Group III of the periodic table or a complex thereof from the viewpoint of good reaction activity. preferable. Specific examples of such a Lewis acid catalyst include aluminum trichloride (AlCl ₃ ), aluminum tribromide (AlBr ₃ ), gallium trichloride (GaCl ₃ ), and boron trifluoride diethyl ether complex (BF ₃ .Et ₂ O) and the like. Among them, AlCl ₃ or BF ₃ .Et ₂ O is preferably used from the viewpoint of versatility and the like. As the Lewis acid catalyst (A), only one kind may be used, or two or more kinds may be used in combination.

  The amount of the Lewis acid catalyst (A) used is not particularly limited, but is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the monomer mixture used for the polymerization. It is.

  Further, the Lewis acid catalyst (A) is adjacent to a halogenated hydrocarbon (B1) in which a halogen atom is bonded to a tertiary carbon atom and a carbon-carbon unsaturated bond, because the polymerization activity can be further increased. May be used in combination with at least one halogenated hydrocarbon (B) selected from halogenated hydrocarbons (B2) in which a halogen atom is bonded to a carbon atom to be formed.

  Specific examples of the halogenated hydrocarbon (B1) having a halogen atom bonded to a tertiary carbon atom include t-butyl chloride, t-butyl bromide, 2-chloro-2-methylbutane, and triphenylmethyl chloride. Among these, t-butyl chloride is particularly preferably used because of its excellent balance between activity and ease of handling. Specific examples of the halogenated hydrocarbon (B2) in which a halogen atom is bonded to a carbon atom adjacent to a carbon-carbon unsaturated bond include benzyl chloride, benzyl bromide, (1-chloroethyl) benzene, allyl chloride, 3-chloro- 1-propyne, 3-chloro-1-butene, 3-chloro-1-butyne, cinnamic acid chloride. Among these, benzyl chloride is preferably used because it has an excellent balance between activity and ease of handling. The halogenated hydrocarbon (B) may be used alone or in combination of two or more.

  The amount of the halogenated hydrocarbon (B) to be used is not particularly limited, but is preferably in the range of 0.05 to 50, more preferably in the range of 0.1 to 10 in a molar ratio to the Lewis acid catalyst (A). .

  In performing the polymerization reaction, the order in which the respective components of the monomer mixture and the polymerization catalyst are added to the polymerization reactor is not particularly limited, and may be added in any order, but from the viewpoint of favorably controlling the polymerization reaction. A part of the monomer components constituting the monomer mixture and the Lewis acid catalyst (A) are previously added to the polymerization reactor, and a part of the monomer components constituting the monomer mixture are After the Lewis acid catalyst (A) is brought into contact with the Lewis acid catalyst in advance, it is preferable to start the polymerization reaction by adding the remaining monomer components constituting the monomer mixture to the polymerization reactor. In this case, at least an alicyclic monoolefin having 4 to 6 carbon atoms is used as a part of the monomer component constituting the monomer mixture, and is added to the polymerization reactor in advance with the Lewis acid catalyst (A). Then, after previously contacting the alicyclic monoolefin having 4 to 6 carbon atoms and the Lewis acid catalyst (A), the remaining monomer components constituting the monomer mixture are added to the polymerization reactor. It is more preferable to start the polymerization reaction.

  When a halogenated hydrocarbon (B) is used in addition to the Lewis acid catalyst (A), the monomer mixture and the Lewis acid catalyst (A) are added to a polymerization reactor to carry out the polymerization reaction. After the start, it is preferred to add the halogenated hydrocarbon (B) to the polymerization reactor. Alternatively, the monomer mixture, the Lewis acid catalyst (A), a part of the halogenated hydrocarbon (B) and a part of the halogenated hydrocarbon (B) are added to the polymerization reactor to initiate the polymerization reaction, and then the remaining halogenated hydrocarbon (B) is added. Is also preferable.

  From the viewpoint of better controlling the polymerization reaction, it is preferable to carry out the polymerization reaction by adding a solvent to the polymerization reaction system. The type of the solvent is not particularly limited as long as it does not inhibit the polymerization reaction, but a saturated aliphatic hydrocarbon or an aromatic hydrocarbon is preferable. Examples of the saturated aliphatic hydrocarbon used as the solvent include n-pentane, n-hexane, 2-methylpentane, 3-methylpentane, n-heptane, 2-methylhexane, 3-methylhexane, and 3-ethylpentane , 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 2,2,3-trimethylbutane, 2,2,4-trimethylpentane A chain saturated aliphatic hydrocarbon having 5 to 10 carbon atoms; a cyclic saturated aliphatic hydrocarbon having 5 to 10 carbon atoms such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane. Examples of the aromatic hydrocarbon used as the solvent include aromatic hydrocarbons having 6 to 10 carbon atoms, such as benzene, toluene, and xylene. The solvent may be used alone or as a mixed solvent of two or more. The amount of the solvent used is not particularly limited, but is preferably from 10 to 1,000 parts by mass, more preferably from 50 to 500 parts by mass, per 100 parts by mass of the monomer mixture used for the polymerization reaction. For example, a mixture of an addition-polymerizable component and a non-addition-polymerizable component such as a mixture of cyclopentane and cyclopentene derived from the C5 fraction is added to the polymerization reaction system, and the addition-polymerizable component is added in a single amount. It is also possible to adopt a mode in which the non-addition polymerizable component is used as a solvent and the non-addition polymerizable component is used as a solvent.

  The polymerization temperature at the time of performing the polymerization reaction is not particularly limited, but is preferably 85 ° C or lower, more preferably -20 to 85 ° C, and still more preferably 0 to 75 ° C. If the polymerization temperature is too low, the polymerization activity may be reduced and the productivity may be inferior. If the polymerization temperature is too high, the hue of the resulting hydrocarbon resin may be inferior. The pressure at which the polymerization reaction is performed may be under atmospheric pressure or under pressure. The polymerization reaction time can be appropriately selected, and is usually selected in the range of 10 minutes to 12 hours, preferably 30 minutes to 6 hours.

  When a desired polymerization conversion is obtained, the polymerization reaction can be stopped by adding a polymerization terminator such as methanol, an aqueous sodium hydroxide solution, or an aqueous ammonia solution to the polymerization reaction system. In addition, the catalyst residue insoluble in the solvent, which is generated when the polymerization catalyst is inactivated by adding a polymerization terminator, may be removed by filtration or the like. After the polymerization reaction is stopped, unreacted monomers and solvent are removed, low molecular weight oligomer components are removed by steam distillation or the like, and the mixture is cooled to obtain a solid hydrocarbon resin.

  The hydrocarbon resin obtained in this manner may be partially or entirely saturated with a hydrogenation reaction (hydrogenation) as necessary, if necessary, in the polymer molecular structure of the hydrocarbon resin, in which some or all of the unsaturated bonds remain. Or hydride.

  When the hydrogenation reaction is performed on the hydrocarbon resin, the hydrogenation reaction method is not particularly limited, and a known method can be used without limitation. For example, a method of contacting with hydrogen in the presence of a nickel catalyst and the like Is mentioned. The nickel catalyst is not particularly limited, but is preferably a catalyst containing, as a main component, a compound obtained by supporting nickel as a metal on a supported inorganic compound as a carrier from the viewpoint of high reactivity. Specific examples of the supported inorganic compound as a carrier include silica, alumina, boria, silica-alumina, diatomaceous earth, clay, clay, magnesia, magnesia-silica (silica-magnesium oxide), titania, zirconia, and the like.

  In the pressure-sensitive adhesive composition of the present invention, the content of the hydrocarbon resin is preferably 10 to 500 parts by mass with respect to 100 parts by mass of the block copolymer composition because more excellent die-cut performance is obtained. Yes, more preferably 30 to 400 parts by mass, even more preferably 50 to 300 parts by mass.

  The pressure-sensitive adhesive composition of the present invention may further contain other components. Other components that can be contained in the pressure-sensitive adhesive composition of the present invention include waxes, antioxidants, softeners, tackifying resins other than the above-described hydrocarbon resins and hydrides, and polymers other than the above-described block copolymers. Other compounding agents such as heat stabilizers, ultraviolet absorbers, and fillers can be added. The pressure-sensitive adhesive composition of the present invention is preferably a solvent-free composition containing no solvent.

  The wax that can be blended in the pressure-sensitive adhesive composition of the present invention is not particularly limited. For example, polyethylene wax, ethylene-vinyl acetate copolymer wax, polyethylene oxide wax, paraffin wax, microcrystalline wax, Fischer-Tropsh wax, Fischer oxide -Tropsh wax, hydrogenated castor oil wax, polypropylene wax, by-product polyethylene wax, stearamide hydroxide wax and the like can be used. One type of wax may be used alone, or two or more types may be used in combination. The content of the wax in the pressure-sensitive adhesive composition is not particularly limited, but is preferably from 10 to 200 parts by mass, more preferably from 20 to 150 parts by mass, per 100 parts by mass of the thermoplastic elastomer. When the content of the wax is in this range, the obtained pressure-sensitive adhesive composition has particularly excellent coating easiness.

  The antioxidant that can be added to the pressure-sensitive adhesive composition of the present invention is not particularly limited. For example, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl- Hindered phenols such as 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,6-di-t-butyl-p-cresol, di-t-butyl-4-methylphenol Compounds; thiodicarboxylate esters such as dilaurylthiopropionate; phosphites such as tris (nonylphenyl) phosphite; and the like. The amount of the antioxidant is not particularly limited, but is usually 10 parts by mass or less, preferably 0.5 to 5 parts by mass, per 100 parts by mass of the thermoplastic elastomer. The antioxidants may be used alone or in a combination of two or more.

  The softener which can be blended in the pressure-sensitive adhesive composition of the present invention is not particularly limited. For example, aromatic, paraffinic or naphthenic process oils; and liquid polymers such as polybutene and polyisobutylene may be used. it can. One type of softener may be used alone, or two or more types may be used in combination.

  As the tackifying resin other than the hydrocarbon resin that can be blended in the pressure-sensitive adhesive composition of the present invention, a conventionally known tackifying resin can be used. Specifically, rosin; modified rosins such as disproportionated rosin and dimerized rosin; esterified products of polyhydric alcohols such as glycol, glycerin and pentaerythritol with rosin or modified rosins; terpene resins; , Aromatic, alicyclic or aliphatic-aromatic copolymer-based hydrocarbon resins or hydrides thereof; phenol resins; coumarone-indene resins. One of these tackifier resins may be used alone, or two or more thereof may be used in combination.

  Other polymers that can be blended in the pressure-sensitive adhesive composition of the present invention include conjugated diene homopolymers such as polybutadiene and polyisoprene, (styrene-butadiene) random copolymer, and (styrene-isoprene) random copolymer. Such as aromatic vinyl-conjugated diene random copolymer, aromatic vinyl-conjugated diene block copolymer such as (styrene-butadiene) block copolymer, aromatic vinyl homopolymer such as polystyrene, isobutylene-based polymer, Examples include, but are not limited to, polymers having elasticity at room temperature (23 ° C.) such as acrylic polymers, ester polymers, ether polymers, urethane polymers, and polyvinyl chloride. . In the pressure-sensitive adhesive composition of the present invention, the content of these polymers is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total amount of the pressure-sensitive adhesive composition.

  In preparing the pressure-sensitive adhesive composition of the present invention, the method of mixing the hydrocarbon resin and / or the hydride, the thermoplastic elastomer, and other components that are further added as necessary is not particularly limited. After dissolving each component in a solvent and mixing uniformly, a method of removing the solvent by heating or the like, a method of melting and mixing each component by a kneader or the like can be used. From the viewpoint of more efficient mixing, melt mixing is preferred among these methods. The temperature at which the melt mixing is performed is not particularly limited, but is usually in the range of 100 to 200 ° C.

  The pressure-sensitive adhesive composition of the present invention can be applied to adhesion of various members. Further, the pressure-sensitive adhesive composition of the present invention can be applied to various uses, and the use is not limited. For example, it can be used to form a pressure-sensitive adhesive layer of a label. . That is, the pressure-sensitive adhesive composition of the present invention can be suitably used as a pressure-sensitive adhesive composition for labels, and a label obtained from the pressure-sensitive adhesive composition for labels has excellent pressure-sensitive adhesive performance and also excellent die-cut performance.

  The pressure-sensitive adhesive composition of the present invention can be applied to label production according to a conventional method. The label preferably includes an adhesive layer made of the adhesive composition of the present invention and a support. The pressure-sensitive adhesive layer can be usually formed by applying the pressure-sensitive adhesive composition of the present invention on a support and drying the composition.

  The support used is not particularly limited, and examples thereof include papers such as kraft paper, Japanese paper, high-quality paper and synthetic paper; cloths such as cotton cloth, soft cloth and polyester cloth; cellophane films, polyvinyl chloride films, and polypropylene films. And a resin film such as a polyethylene film; a metal foil such as an aluminum foil and a copper foil; and a nonwoven fabric such as a polyester nonwoven fabric and a rayon nonwoven fabric.

  These supports may be those whose surfaces have been previously subjected to corona discharge treatment or to which a primary coating agent has been applied.

  The application method is not particularly limited, and a conventionally known method can be employed. For example, the pressure-sensitive adhesive composition of the present invention is dissolved in a suitable organic solvent to adjust the viscosity, a method of applying the obtained coating liquid, a method of applying heat and melting the pressure-sensitive adhesive composition directly, using an emulsifier Then, a method of dispersing the pressure-sensitive adhesive composition in water to prepare an emulsion and applying the emulsion can be employed.

  Examples of the organic solvent for dissolving the pressure-sensitive adhesive composition include aliphatic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; and halides thereof.

  The label can be produced by applying a coating solution containing the pressure-sensitive adhesive composition on a support and drying the same to form a pressure-sensitive adhesive layer. Further, the label is melted by heating the pressure-sensitive adhesive composition, the obtained melt is applied on a release agent layer of a release sheet, and dried if necessary to form a pressure-sensitive adhesive layer, Thereafter, it may be manufactured by a method of bonding to a support (transfer coating method). Or, the label is melted by heating the pressure-sensitive adhesive composition, the obtained melt is directly applied to a support, and dried if necessary to form a pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive It may be manufactured by a method of laminating a layer and a release agent layer of a release sheet (direct coating method).

Since the obtained pressure-sensitive adhesive layer is formed using the pressure-sensitive adhesive composition of the present invention, the pressure-sensitive adhesive layer has excellent adhesive performance and also has excellent die-cut performance.
The thickness of the pressure-sensitive adhesive layer is usually 10 μm to 100 μm, preferably 20 μm to 70 μm.

  The label obtained by using the pressure-sensitive adhesive composition of the present invention may be cut or punched into an appropriate shape according to the intended use. Further, the pressure-sensitive adhesive layer of the label using the pressure-sensitive adhesive composition of the present invention is not limited to a continuously formed pressure-sensitive adhesive layer. For example, the pressure-sensitive adhesive layer may be formed in a regular or random pattern such as a dot shape or a stripe shape.

  Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples. In the following, “parts” are based on mass unless otherwise specified. In addition, the test and evaluation were based on the following.

[Number average molecular weight, weight average molecular weight, Z average molecular weight and molecular weight distribution]
Gel permeation chromatography analysis of the sample hydrocarbon resin was performed to determine the number average molecular weight (Mn), weight average molecular weight (Mw) and Z average molecular weight (Mz) in terms of standard polystyrene. It was shown by the ratio of Mw / Mn or the ratio of Mz / Mw. The gel permeation chromatography analysis uses "HLC-8320GPC" manufactured by Tosoh Corporation as a measuring device, and uses a column in which three "TSKgel SuperMultipore HZ" manufactured by Tosoh Corporation are connected, and uses tetrahydrofuran as a solvent. , 40 ° C., and a flow rate of 1.0 ml / min.

[Softening point (℃)]
The hydrocarbon resin used as a sample was measured by the ring and ball method according to JIS K2207.

(Weight average molecular weight of each block copolymer in the block copolymer composition and the block copolymer composition)
The molecular weight was determined as high molecular weight in terms of polystyrene by high performance liquid chromatography using tetrahydrofuran as a carrier at a flow rate of 0.35 mL / min. The apparatus is HLC8220 (manufactured by Tosoh Corporation), the column is a combination of three Shodex (registered trademark) [KF-404HQ manufactured by Showa Denko KK] (column temperature 40 ° C), and the detector is a differential refractometer and an ultraviolet detector. Calibration of molecular weight was performed at 12 points of standard polystyrene (5 to 3 million) manufactured by Polymer Laboratory.

(Content of each block copolymer in the block copolymer composition)
It was determined from the area ratio of peaks corresponding to each block copolymer in the chart obtained by the high performance liquid chromatography.

(Weight average molecular weight of polyaromatic vinyl 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 polyisoprene block of the block copolymer. Specifically, the following procedure was performed. That is, 300 mg of a sample was dissolved in a reaction vessel containing 100 mL of dichloromethane treated with a molecular sieve. After putting the reaction vessel into a cooling bath and setting it at -25 ° C, ozone generated by an ozone generator was introduced while flowing oxygen into the reaction vessel at a flow rate of 170 mL / min. After a lapse of 30 minutes from the start of the reaction, the gas flowing out of the reaction vessel was introduced into an aqueous potassium iodide solution to confirm that the reaction was completed. The obtained reaction liquid is referred to as reaction liquid 1.
Next, 50 mL of diethyl ether and 470 mg of lithium aluminum hydride were charged into another reaction vessel whose inside was replaced with nitrogen, and the reaction solution 1 was slowly dropped into this reaction vessel while cooling the reaction vessel with ice water. Then, the reaction vessel was placed in a water bath, the temperature was gradually raised, and the mixture was refluxed at 40 ° C. for 30 minutes. After completion of the reaction, dilute hydrochloric acid was added dropwise to the reaction vessel little by little while stirring the solution, and the dropwise addition was continued until almost no generation of hydrogen was observed. The obtained reaction liquid is referred to as reaction liquid 2. A solid product generated in the reaction solution 2 was separated by filtration, 100 mL of diethyl ether was added to the filtered solid product, the whole volume was stirred for 10 minutes, and then filtered to obtain an extract. This extract was combined with the filtrate obtained by filtration, and the solvent was distilled off from the combined solution to obtain a solid sample.
The weight average molecular weight of the thus obtained sample was measured in accordance with the above-mentioned method for measuring the weight average molecular weight, and the value was defined as the weight average molecular weight of the polyaromatic vinyl block.

(Weight average molecular weight of polyisoprene block of block copolymer)
The weight average molecular weight of the polyisoprene block was determined based on the calculated value by subtracting the weight average molecular weight of the corresponding polyaromatic vinyl block from the weight average molecular weight of the block copolymer obtained as described above. Was.

(Aromatic vinyl monomer unit content of the block copolymer)
It was determined based on the detection intensity ratio between the differential refractometer and the ultraviolet detector in the above-described high performance liquid chromatography measurement. In addition, copolymers having different aromatic vinyl monomer unit contents were prepared in advance, and a calibration curve was prepared using them.

[Aromatic vinyl monomer unit content of block copolymer composition (whole)]
^It was determined based on the ¹ H-NMR measurement.

(Breaking strength and breaking elongation)
Using a 1 mm thick sheet of the pressure-sensitive adhesive composition press-formed at 170 ° C., the breaking strength and the breaking elongation were measured by a method according to JIS K6251. The dumbbell shape used was JIS-7113-2 (1/2 size).

[Die cut performance]
An adhesive composition was applied to a polyester film having a thickness of 55 μm to prepare an A4 size adhesive film. The pressure-sensitive adhesive film was attached to a release paper to produce a label, and 10 of the obtained labels were stacked to obtain a sample. The sample was cut using a guillotine cutter, and the presence or absence of dirt on the blade of the guillotine cutter and the presence or absence of stringing of the adhesive composition were visually observed and evaluated according to the following criteria.
State of blade after cutting 〇: Dirt was not observed ×: Dirt was observed Presence or absence of threading after cutting 〇: No threading was observed ×: Threading was observed

[Production Example 1]
A mixture of 36.9 parts of cyclopentane, 15.2 parts of cyclopentene and 2.1 parts of toluene was charged into a polymerization reactor, and the temperature was raised to 55 ° C., and 0.75 parts of aluminum trichloride was added. Subsequently, a mixture of 68.7 parts of 1,3-pentadiene, 12.2 parts of cyclopentene and 2.4 parts of isobutylene was continuously added to the polymerization reactor at a temperature of 70 ° C. for 60 minutes. Polymerization was performed. Thereafter, an aqueous sodium hydroxide solution was added to the polymerization reactor to stop the polymerization reaction. At this time, the polymerization conversion was 85%. The types and amounts of the components in the polymerization reactor during the polymerization reaction depend on the components constituting the monomer mixture (addition polymerizable components), the components corresponding to the solvent (non-addition polymerizable components), and the polymerization catalyst. Table 1 summarizes the classification. After removing the precipitate generated by the termination of the polymerization by filtration, the obtained polymer solution was charged into a distillation still and heated under a nitrogen atmosphere to remove the polymerization solvent and unreacted monomers. Then, at 240 ° C. or higher, low-molecular-weight oligomer components were distilled off while blowing saturated steam. Pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (trade name "Irganox (registered trademark) 1010") is used as an antioxidant based on 100 parts of the molten resin. After adding and mixing 0.2 parts of the molten resin, the molten resin was taken out of the distillation still and allowed to cool to room temperature to obtain a hydrocarbon resin. Physical properties of the obtained hydrocarbon resin were measured. Table 1 shows the results.

[Production Examples 2 to 7]
A hydrocarbon resin was obtained in the same manner as in Production Example 1 except that the types and amounts of the components added to the polymerization reactor were changed as shown in Table 1, and the physical properties were measured in the same manner as in Production Example 1. Table 1 shows the results.

(Production Example of Block Copolymer Composition)
23.3 kg of cyclohexane, 2.8 mmol of N, N, N ', N'-tetramethylethylenediamine (hereinafter referred to as TMEDA) and 1.31 kg of styrene were added to the pressure-resistant reactor, and the mixture was stirred at 40 ° C. Meanwhile, 92.10 mmol of n-butyllithium was added, and polymerization was carried out for 1 hour while heating to 50 ° C. The polymerization conversion of styrene was 100%.
Subsequently, 6.61 kg of isoprene was continuously added to the reactor over 1 hour while controlling the temperature so as to keep the temperature at 50 to 60 ° C.
After the addition of isoprene was completed, polymerization was carried out for another 1 hour. Thereafter, 64.3 mmol of methanol as a polymerization terminator was added to the reactor to carry out a polymerization termination reaction for 1 hour. The styrene-isoprene diblock copolymer was formed by deactivating the active terminal in some parts.
Thereafter, 0.80 kg of styrene was continuously added over 1 hour while controlling the temperature so as to maintain 50 to 60 ° C. After the addition of styrene was completed, polymerization was carried out for an additional hour to form a triblock chain. The polymerization conversion of styrene was 100%. Thereafter, 300 mmol of methanol was added as a polymerization terminator and mixed to deactivate all the active terminals of the triblock chain, thereby forming a styrene-isoprene-styrene triblock copolymer.
A part of the reaction solution containing the block copolymer composition obtained as described above was taken out, and the block copolymer composition was evaluated according to the above measurement method. Table 2 shows the results.

  To 100 parts of the reaction solution obtained as described above (containing 30 parts of the polymer component), 0.3 part of 2,6-di-tert-butyl-p-cresol as an antioxidant was added and mixed. The mixed solution was dropped little by little into warm water heated to 85 to 95 ° C. to volatilize the solvent to obtain a precipitate. The precipitate was pulverized and dried at 85 ° C. with hot air to obtain a block copolymer. The coalesced composition was recovered.

[Example 1]
100 parts of the block copolymer composition obtained in the above Production Example was charged into a stirring blade type kneader, and 150 parts of the hydrocarbon resin obtained in Production Example 1 and a softener (trade name “SUNPURE N90”) were added thereto. , Naphthenic process oil, manufactured by Nippon Sun Oil Co., Ltd.) and 50 parts of an antioxidant (trade name “Irganox 1010”, manufactured by BASF) were added, and the system was replaced with nitrogen gas. A pressure-sensitive adhesive composition was prepared by kneading at ~ 180 ° C for 1 hour.

  Using the obtained pressure-sensitive adhesive composition, the breaking strength and the breaking elongation were measured by the methods described above, and the die-cut performance was evaluated. Table 3 shows the results.

[Examples 2 to 6, Comparative Examples 1 to 3]
Except having changed into the composition of Table 3, it carried out similarly to Example 1, and prepared the adhesive composition and evaluated similarly to Example 1. Table 3 shows the results. The softener used in Example 5 and the like is “Knife Rex 222B” (trade name), a naphthenic process oil, manufactured by Nainus Corporation.

From Table 3, the following points can be confirmed.
That is, a block copolymer composition containing a triblock copolymer and a diblock copolymer, wherein the content of aromatic vinyl monomer units in the entire polymer component is 10 to 30% by mass, Group hydrocarbon unit having a Z-average molecular weight of not less than 5,000, a breaking strength of less than 6.0 MPa, and a breaking elongation. The label obtained using the pressure-sensitive adhesive composition having a content of less than 1,300% could be cut with a guillotine cutter without staining the sword and without pulling the thread of the pressure-sensitive adhesive composition. Therefore, it was found that the pressure-sensitive adhesive composition had excellent die-cut performance (Examples 1 to 6).
On the other hand, a label obtained using a pressure-sensitive adhesive composition containing a block copolymer composition and a hydrocarbon resin having a Z-average molecular weight that is too small, and having a breaking strength and a breaking elongation that are too large, is cut with a guillotine cutter. Became dirty, and the pressure-sensitive adhesive composition pulled a thread (Comparative Examples 1 to 3).

Claims (5)

A pressure-sensitive adhesive composition containing a block copolymer composition and a hydrocarbon resin,
The block copolymer composition contains an aromatic vinyl-isoprene-aromatic vinyl triblock copolymer and an aromatic vinyl-isoprene diblock copolymer, and the block copolymer composition contains The content of the aromatic vinyl monomer unit in the whole united component is 10 to 30% by mass,
The hydrocarbon resin contains an aliphatic monomer unit, or an aliphatic monomer unit and an aromatic monomer unit, and the content of the aromatic monomer unit in the hydrocarbon resin is all 40% by mass or less based on the monomer unit, the hydrocarbon resin has a Z-average molecular weight of 5,000 or more,
A pressure-sensitive adhesive composition having a breaking strength of less than 6.0 MPa and a breaking elongation of less than 1,300%.   The pressure-sensitive adhesive composition according to claim 1, wherein the hydrocarbon resin has a weight average molecular weight of 2,500 or more and a softening point of 90C or more. The triblock copolymer,
Formula ^{(A): Ar1 a -D a} -Ar2 a
(Wherein, Ar @ 1 ^a is a poly vinyl aromatic block having a weight average molecular weight of 5,000 to 20,000, Ar @ 2 ^a is a poly vinyl aromatic block having a weight average molecular weight of 25,000~400,000, ^{D a} Represents a polyisoprene block.) The pressure-sensitive adhesive composition according to claim 1 or 2, wherein   The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the content of the hydrocarbon resin is 10 to 500 parts by mass with respect to 100 parts by mass of the block copolymer composition.   A pressure-sensitive adhesive composition for a label, comprising the pressure-sensitive adhesive composition according to claim 1.