Method for producing hydrocarbon resin

Abstract

To provide a method for producing a hydrocarbon resin which can produce a hydrocarbon resin capable of giving a hot-melt adhesive composition having low temperature characteristics and excellent adhesive force and holding force with high productivity.SOLUTION: A method for producing a hydrocarbon resin that includes a step of polymerizing a monomer by cationic polymerization using a Lewis acid catalyst in a hydrocarbon solvent, includes a first polymerization step of polymerizing a first monomer containing 80 mass% or more of an aromatic monomer, and a second polymerization step of polymerizing a second monomer containing 60 mass% or more of an aliphatic monomer, wherein a use ratio of the first monomer in the first polymerization step is 1-35 mass% with respect to the total amount of the monomer used in polymerization.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a hydrocarbon resin with high productivity, which can provide a hot-melt pressure-sensitive adhesive composition having excellent low-temperature properties, adhesive strength and holding power. [Background technology]

[0002] Hydrocarbon resins having carbon-carbon double bonds, such as hydrocarbon resins obtained by copolymerizing monoolefinically unsaturated hydrocarbons with linear conjugated diolefins, are known. Such hydrocarbon resins are used, for example, as tackifier resins for forming hot-melt pressure-sensitive adhesive compositions.

[0003] As such a hydrocarbon resin, for example, Patent Document 1 discloses a hydrocarbon resin obtained by mixing an aromatic hydrocarbon resin having a softening point of 140 to 180° C. with a non-aromatic hydrocarbon resin having a softening point of 70 to 110° C. The technology of Patent Document 1 describes that by using a mixture of an aromatic hydrocarbon resin and a non-aromatic hydrocarbon resin as the hydrocarbon resin, when used as a tackifier for a styrene-conjugated diene block copolymer, the resulting pressure-sensitive adhesive composition can be made excellent in tack, adhesive strength, and holding power. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-157686 Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology of Patent Document 1, an aromatic hydrocarbon resin and a non-aromatic hydrocarbon resin are produced separately and then mixed together, but the inventors of the present invention have found that the technology of Patent Document 1 has the following problems: When an aromatic hydrocarbon resin is produced alone, the aromatic hydrocarbon resin has a high melt viscosity and is poor in liquid transportability in a molten state, and when a non-aromatic hydrocarbon resin is produced alone, the non-aromatic hydrocarbon resin is prone to blocking and is therefore poor in handleability, and therefore improvements were necessary from the perspective of improving productivity.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a hydrocarbon resin with high productivity, which can provide a hot melt pressure-sensitive adhesive composition having excellent low temperature properties, adhesive strength and holding power. [Means for solving the problem]

[0007]

[0010] The present inventors have conducted studies to achieve the above-mentioned object, and have found that, when producing a hydrocarbon resin by polymerizing monomers in a hydrocarbon solvent by cationic polymerization using a Lewis acid catalyst, the process comprises separately a step of polymerizing a first monomer containing an aromatic monomer in a proportion of 80 mass% or more and a step of polymerizing a second monomer containing an aliphatic monomer in a proportion of 60 mass% or more, and further, by setting the proportion of the first monomer used in these steps within a specific range, a hydrocarbon resin capable of giving a hot-melt pressure-sensitive adhesive composition excellent in low-temperature properties, adhesive strength and holding power can be produced with high productivity, and have completed the present invention.

[0008] That is, according to the present invention, there is provided a method for producing a hydrocarbon resin, comprising a step of polymerizing a monomer by cationic polymerization in a hydrocarbon solvent using a Lewis acid catalyst, a first polymerization step of polymerizing a first monomer containing an aromatic monomer in a proportion of 80% by mass or more; a second polymerization step of polymerizing a second monomer containing an aliphatic monomer in a proportion of 60% by mass or more, There is provided a method for producing a hydrocarbon resin, wherein the proportion of the first monomer used in the first polymerization step is 1 to 35 mass % based on the total amount of monomers used in polymerization.

[0009] In the present invention, the first monomer preferably contains at least one selected from the group consisting of a styrene compound, an indene compound, and a C9 fraction. In the present invention, the second monomer preferably contains 1 to 60% by mass of a 1,3-pentadiene monomer, 1 to 30% by mass of an alicyclic monoolefin monomer having 4 to 6 carbon atoms, 0 to 65% by mass of an acyclic monoolefin monomer having 4 to 8 carbon atoms, 0 to 10% by mass of an alicyclic diolefin monomer, and 0 to 40% by mass of an aromatic monoolefin monomer. In the present invention, it is preferable that the softening point of the first polymer formed by polymerization in the first polymerization step is 140 to 200°C, and the softening point of the second polymer formed by polymerization in the second polymerization step is 50 to 120°C. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for producing a hydrocarbon resin with high productivity, which can provide a hot melt pressure-sensitive adhesive composition excellent in low temperature properties, adhesive strength and holding power. DETAILED DESCRIPTION OF THE INVENTION

[0011] The method for producing a hydrocarbon resin of the present invention comprises: 1. A method for producing a hydrocarbon resin, comprising a step of polymerizing a monomer by cationic polymerization in a hydrocarbon solvent using a Lewis acid catalyst, a first polymerization step of polymerizing a first monomer containing an aromatic monomer in a proportion of 80% by mass or more; a second polymerization step of polymerizing a second monomer containing an aliphatic monomer in a proportion of 60% by mass or more, The proportion of the first monomer used in the first polymerization step is 1 to 35% by mass based on the total amount of monomers used in polymerization.

[0012] <Hydrocarbon resin> First, the hydrocarbon resin produced by the production method of the present invention will be described. The hydrocarbon resin produced by the production method of the present invention is not particularly limited as long as it is obtained by polymerizing a monomer by cationic polymerization using a Lewis acid catalyst.

[0013] The hydrocarbon resin produced by the production method of the present invention is not particularly limited, but is preferably a C5 / C9 hydrocarbon resin.

[0014] The C5 / C9 hydrocarbon resin refers to a hydrocarbon resin obtained by polymerizing a monomer containing at least one type of monomer contained in the C5 fraction obtained by thermal cracking of naphtha and at least one type of monomer contained in the C9 fraction obtained by thermal cracking of naphtha.

[0015] Examples of monomers contained in the C5 fraction include conjugated diene monomers having 4 to 5 carbon atoms, such as 1,3-pentadiene, isoprene, and cyclopentadiene. Of these, it is preferable that the C5 fraction contains 1,3-pentadiene, that is, that the hydrocarbon resin contains 1,3-pentadiene monomer units.

[0016] The monomers contained in the C5 fraction and the monomers contained in the C9 fraction described below may be any monomers that can be contained in the C5 fraction or C9 fraction when naphtha is thermally cracked. For example, the monomers contained in the C5 fraction and the C9 fraction are not limited to monomers obtained as the C5 fraction by thermally cracking naphtha or monomers obtained as the C9 fraction by thermally cracking naphtha, but may also be monomers obtained by other synthesis methods, etc.

[0017] Examples of monomers contained in the C9 fraction include styrene compounds such as styrene, α-methylstyrene, β-methylstyrene, and vinyltoluene; indene compounds such as indene and 1-methylindene; and aromatic monoolefins having 8 to 10 carbon atoms such as coumarone.

[0018] More specifically, such a C5 / C9 hydrocarbon resin is preferably a hydrocarbon resin containing at least a 1,3-pentadiene monomer unit and an alicyclic monoolefin monomer unit having 4 to 6 carbon atoms as aliphatic monomer units, and an aromatic monoolefin monomer unit as an aromatic monomer unit, and the hydrocarbon resin may further contain, as necessary, an acyclic monoolefin monomer unit having 4 to 8 carbon atoms and an alicyclic diolefin monomer unit as aliphatic monomer units.

[0019] The content of the 1,3-pentadiene monomer unit in the hydrocarbon resin is not particularly limited, but is preferably 1 to 60 mass%, more preferably 10 to 55 mass%, even more preferably 15 to 50 mass%, still more preferably 20 to 45 mass%, and particularly preferably 22 to 43 mass%. By setting the content of the 1,3-pentadiene monomer unit within the above range, the hot melt pressure-sensitive adhesive composition can have better low temperature properties.

[0020] The alicyclic monoolefin having 4 to 6 carbon atoms that forms the alicyclic monoolefin monomer unit having 4 to 6 carbon atoms is a hydrocarbon compound having one ethylenically unsaturated bond and a non-aromatic ring structure in its molecular structure. Specific examples of the alicyclic monoolefin having 4 to 6 carbon atoms include cyclobutene, cyclopentene, cyclohexene, methylcyclobutene, and methylcyclopentene.

[0021] The content of the alicyclic monoolefin monomer unit having 4 to 6 carbon atoms in the hydrocarbon resin is not particularly limited, but is preferably 1 to 30 mass%, more preferably 3 to 27 mass%, even more preferably 5 to 26 mass%, still more preferably 7 to 25 mass%, and particularly preferably 7 to 24 mass%. By setting the content of the alicyclic monoolefin monomer unit having 4 to 6 carbon atoms in the above range, when it is made into a hot melt pressure-sensitive adhesive composition, it is possible to make the low temperature properties more excellent.

[0022] The proportion of each compound in the alicyclic monoolefin having 4 to 6 carbon atoms may be any proportion and is not particularly limited, but it is preferable that at least cyclopentene is contained, and the proportion of cyclopentene in the alicyclic monoolefin having 4 to 6 carbon atoms is more preferably 50 mass% or more, and even more preferably 80 mass% or more.

[0023] The aromatic monoolefins that make up the aromatic monoolefin monomer units are aromatic compounds with one ethylenically unsaturated bond in their molecular structure. Examples of aromatic monoolefins include styrene compounds such as styrene, α-methylstyrene, β-methylstyrene, and vinyltoluene; indene compounds such as indene and 1-methylindene; and coumarone.

[0024] The content of the aromatic monoolefin monomer unit in the hydrocarbon resin is not particularly limited, but is preferably 0.8 to 50 mass%, more preferably 3 to 45 mass%, even more preferably 5 to 35 mass%, and particularly preferably 6 to 27 mass%. By setting the content of the aromatic monoolefin monomer unit within the above range, when it is made into a hot melt pressure-sensitive adhesive composition, it is possible to make it possible to make the adhesive strength and holding power more excellent.

[0025] The acyclic monoolefin having 4 to 8 carbon atoms that forms the acyclic monoolefin monomer unit having 4 to 8 carbon atoms is a chain hydrocarbon compound having 4 to 8 carbon atoms and no ring structure, and having one ethylenically unsaturated bond in its molecular structure. Specific examples of the acyclic monoolefin having 4 to 8 carbon atoms include butenes such as 1-butene, 2-butene, and isobutylene (2-methylpropene); pentenes such as 1-pentene, 2-pentene, 2-methyl-1-butene, 3-methyl-1-butene, and 2-methyl-2-butene; hexenes such as 1-hexene, 2-hexene, and 2-methyl-1-pentene; heptenes such as 1-heptene, 2-heptene, and 2-methyl-1-hexene; and octenes such as 1-octene, 2-octene, 2-methyl-1-heptene, and diisobutylene (2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-1-pentene).

[0026] The content of the acyclic monoolefin monomer unit having 4 to 8 carbon atoms in the hydrocarbon resin is not particularly limited, but is preferably 0 to 50 mass%, more preferably 10 to 47 mass%, even more preferably 20 to 45 mass%, and particularly preferably 27 to 43 mass%. By setting the content of the acyclic monoolefin monomer unit having 4 to 8 carbon atoms in the above range, the hot melt pressure-sensitive adhesive composition can have better low temperature properties.

[0027] The alicyclic diolefin 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. Specific examples of the alicyclic diolefin include cyclopentadiene, cyclopentadiene polymers such as dicyclopentadiene, methylcyclopentadiene, and methylcyclopentadiene polymers.

[0028] The content of the alicyclic diolefin monomer unit in the hydrocarbon resin is not particularly limited, but is preferably 0 to 10 mass%, more preferably 0.5 to 8 mass%, even more preferably 1 to 6 mass%, and particularly preferably 1.5 to 4.5 mass%. By setting the content of the alicyclic diolefin monomer unit within the above range, when it is made into a hot melt pressure-sensitive adhesive composition, it is possible to make the low temperature properties more excellent.

[0029] Furthermore, the hydrocarbon resin produced by the production method of the present invention may contain other monomer units in addition to 1,3-pentadiene monomer units, alicyclic monoolefin monomer units having 4 to 6 carbon atoms, aromatic monoolefin monomer units, acyclic monoolefin monomer units having 4 to 8 carbon atoms, and alicyclic diolefin monomer units.

[0030] The other monomers forming such other monomer units are not particularly limited as long as they are addition-polymerizable compounds that can be addition-copolymerized with 1,3-pentadiene, etc. Examples of such other monomers include unsaturated hydrocarbons having 4 to 6 carbon atoms other than 1,3-pentadiene, such as 1,3-butadiene, 1,2-butadiene, isoprene, 1,3-hexadiene, and 1,4-pentadiene; alicyclic monoolefins having 7 or more carbon atoms, such as cycloheptene; and acyclic monoolefins having 4 to 8 carbon atoms other than 1,3-pentadiene, such as ethylene, propylene, and nonene.

[0031] The content of other monomer units in the hydrocarbon resin is usually within a range of 0 to 30% by mass, preferably 0 to 25% by mass, and more preferably 0 to 20% by mass.

[0032] The number-average molecular weight (Mn) of the hydrocarbon resin obtained by the production method of the present invention is preferably in the range of 500 to 2000, more preferably in the range of 600 to 1500, and even more preferably in the range of 700 to 1400. The weight-average molecular weight (Mw) of the hydrocarbon resin obtained by the production method of the present invention is preferably in the range of 1000 to 4000, more preferably in the range of 1200 to 3500, and even more preferably in the range of 1400 to 2800. Furthermore, the Z-average molecular weight (Mz) of the hydrocarbon resin obtained by the production method of the present invention is preferably in the range of 2000 to 15000, more preferably in the range of 2500 to 12000, and even more preferably in the range of 2800 to 10000.

[0033] The ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) of the hydrocarbon resin obtained by the production method of the present invention is preferably in the range of 1.2 to 3.5, more preferably in the range of 1.5 to 3.0, and even more preferably in the range of 1.7 to 2.6. The ratio of Z-average molecular weight to weight-average molecular weight (Mz / Mw) of the hydrocarbon resin obtained by the production method of the present invention is preferably in the range of 1.8 to 5.0, more preferably in the range of 1.9 to 4.5, and even more preferably in the range of 2.1 to 4.0.

[0034] By setting the number average molecular weight (Mn), weight average molecular weight (Mw), Z average molecular weight (Mz), ratio of weight average molecular weight to number average molecular weight (Mw / Mn), and ratio of Z average molecular weight to weight average molecular weight (Mz / Mw) within the above ranges, for example, when the hydrocarbon resin is used in a hot melt pressure-sensitive adhesive composition, the compatibility with the base polymer can be improved, and thus the adhesive performance can be improved.

[0035] The number average molecular weight (Mn), weight average molecular weight (Mw), Z average molecular weight (Mz), ratio of weight average molecular weight to number average molecular weight (Mw / Mn), and ratio of Z average molecular weight to weight average molecular weight (Mz / Mw) of hydrocarbon resins can be determined as polystyrene-equivalent values ​​by high performance liquid chromatography.

[0036] The softening point of the hydrocarbon resin obtained by the production method of the present invention is not particularly limited, but is preferably 30°C or higher, more preferably 50°C to 125°C, even more preferably 60°C to 115°C, and particularly preferably 80°C to 110°C. By setting the softening point within the above range, for example, long-term storage is possible without blocking, and when the hydrocarbon resin is used in a hot-melt pressure-sensitive adhesive composition, the resin is easily melted during hot-melt kneading and its compatibility with the base polymer can be improved, thereby improving adhesive performance. The softening point of the hydrocarbon resin can be measured in accordance with JIS K 6863.

[0037] <Method of manufacturing hydrocarbon resin> Next, the method for producing the hydrocarbon resin of the present invention will be described. The method for producing a hydrocarbon resin of the present invention comprises: 1. A method for producing a hydrocarbon resin, comprising a step of polymerizing a monomer by cationic polymerization in a hydrocarbon solvent using a Lewis acid catalyst, a first polymerization step of polymerizing a first monomer containing an aromatic monomer in a proportion of 80% by mass or more; a second polymerization step of polymerizing a second monomer containing an aliphatic monomer in a proportion of 60% by mass or more, The proportion of the first monomer used in the first polymerization step is 1 to 35% by mass based on the total amount of monomers used in polymerization.

[0038] The first polymerization step of the production method of the present invention is a step of polymerizing a first monomer containing an aromatic monomer in a proportion of 80 mass% or more by cationic polymerization in a hydrocarbon solvent using a Lewis acid catalyst.

[0039] The Lewis acid catalyst may be, but is not limited to, a Friedel-Crafts cationic polymerization catalyst. The Friedel-Crafts cationic polymerization catalyst may be, but is not limited to, a halide of aluminum, iron, tantalum, zirconium, tin, beryllium, boron, antimony, gallium, bismuth, molybdenum, or the like. Among these, aluminum halides such as aluminum chloride (AlCl3) and aluminum bromide (AlBr3) are preferred. The amount of the Friedel-Crafts cationic polymerization catalyst used is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the total amount of monomers used in the polymerization (e.g., the total of the first monomer used in the first polymerization step and the second monomer used in the second polymerization step).

[0040] During polymerization, a halogenated hydrocarbon may be used in addition to the Friedel-Crafts type cationic polymerization catalyst, since this allows for further enhancement of catalytic activity.

[0041] Specific examples of halogenated hydrocarbons include halogenated hydrocarbons in which a halogen atom is bonded to a tertiary carbon atom, such as t-butyl chloride, t-butyl bromide, 2-chloro-2-methylbutane, and triphenylmethyl chloride; and halogenated hydrocarbons in which a halogen atom is bonded to a carbon atom adjacent to a carbon-carbon unsaturated bond, such as benzyl chloride, benzyl bromide, (1-chloroethyl)benzene, allyl chloride, 3-chloro-1-propyne, 3-chloro-1-butene, 3-chloro-1-butyne, and cinnamic chloride. Among these, t-butyl chloride and benzyl chloride are preferred from the viewpoint of achieving an excellent balance between catalytic activity and ease of handling. The halogenated hydrocarbons may be used alone or in combination of two or more. The amount of halogenated hydrocarbon used, expressed as a molar ratio relative to the Friedel-Crafts cationic polymerization catalyst, is preferably in the range of 0.05 to 50, more preferably 0.1 to 10.

[0042] The hydrocarbon solvent is not particularly limited as long as it does not inhibit the polymerization reaction, but saturated aliphatic hydrocarbons or aromatic hydrocarbons are preferred. Examples of saturated aliphatic hydrocarbons include linear saturated aliphatic hydrocarbons having 5 to 10 carbon atoms, such as n-pentane, n-hexane, 2-methylpentane, 3-methylpentane, n-heptane, 2-methylhexane, 3-methylhexane, 3-ethylpentane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 2,2,3-trimethylbutane, and 2,2,4-trimethylpentane; and cyclic saturated aliphatic hydrocarbons having 5 to 10 carbon atoms, such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane. Examples of aromatic hydrocarbons include aromatic hydrocarbons having 6 to 10 carbon atoms, such as benzene, toluene, and xylene. The hydrocarbon solvents may be used alone or in combination. The amount of hydrocarbon solvent used is not particularly limited, but is preferably 10 to 1,000 parts by mass, and more preferably 50 to 500 parts by mass, per 100 parts by mass of the total amount of monomers used in the polymerization (for example, the total amount of the first monomer used in the first polymerization step and the second monomer used in the second polymerization step). Note that a portion of the hydrocarbon solvent may be added to the polymerization system in a state where it is contained in the first monomer used in the first polymerization step or the second monomer used in the second polymerization step.

[0043] In the first polymerization step of the production method of the present invention, a first monomer containing 80% by mass or more of an aromatic monomer is polymerized. According to the first polymerization step, a first polymer containing 80% by mass or more of aromatic monomer units is formed in a state of being dissolved in a hydrocarbon solvent.

[0044] The first monomer used in the first polymerization step may contain 80 mass% or more of aromatic monomer, more preferably 87 to 99 mass%, and even more preferably 85 to 98 mass% of aromatic monomer. If the aromatic monomer content is too low, the resulting hot-melt pressure-sensitive adhesive composition will have poor adhesive strength and holding power.

[0045] The aromatic monomer constituting the first monomer is not particularly limited, but the above-mentioned aromatic monoolefins can be used, and it is preferable that the aromatic monoolefin contains at least one selected from styrene compounds and indene compounds. Alternatively, it is also preferable to use a C9 fraction together with or instead of a styrene compound and / or an indene compound.

[0046] The first monomer used in the first polymerization step may contain at least 80% by mass of aromatic monomers, and may also contain a monomer other than the aromatic monomer, such as an aliphatic monomer. Examples of aliphatic monomers include 1,3-pentadiene, alicyclic monoolefins having 4 to 6 carbon atoms, acyclic monoolefins having 4 to 8 carbon atoms, and alicyclic diolefins, as well as other monomers that form the above-mentioned other monomer units. When a C9 fraction is used as the first monomer used in the first polymerization step, the first monomer will contain, as an aliphatic monomer, an aliphatic monomer contained in the C9 fraction (e.g., dicyclopentadiene).

[0047] The method of adding the first monomer to the polymerization system in the first polymerization step is not particularly limited, and may be a method of adding the first monomer to the polymerization system all at once at the start of polymerization, or a method of continuously adding the first monomer dropwise to the polymerization system. However, from the viewpoint of reaction temperature and controllability of polymerization, a method of continuously adding the first monomer dropwise to the polymerization system is preferred.

[0048] The amount of the first monomer used in the first polymerization step is 1 to 35 parts by mass, preferably 4 to 32 parts by mass, and more preferably 7 to 30 parts by mass, relative to 100 parts by mass of the total amount of the monomers used in the polymerization (for example, the total amount of the first monomer used in the first polymerization step and the second monomer used in the second polymerization step). If the amount of the first monomer used is too small, the resulting hot-melt pressure-sensitive adhesive composition will have poor adhesive strength and holding power, while if the amount of the first monomer used is too large, the resulting hot-melt pressure-sensitive adhesive composition will have poor low-temperature properties.

[0049] The softening point of the first polymer formed in the first polymerization step is not particularly limited, but is preferably 140 to 200°C, more preferably 145 to 190°C, and even more preferably 150 to 180°C. When the softening point is in the above range, the hot-melt pressure-sensitive adhesive composition can have more excellent holding power properties. The softening point of the first polymer can be measured in accordance with JIS K 6863.

[0050] The polymerization temperature when carrying out the polymerization reaction in the first polymerization step is not particularly limited, but is preferably −20° C. to 100° C., more preferably 10° C. to 80° C. The polymerization reaction time may be appropriately selected, but is usually 5 minutes to 12 hours, preferably 10 minutes to 6 hours.

[0051] The second polymerization step is a step of polymerizing a second monomer containing 60% by mass or more of an aliphatic monomer in a hydrocarbon solvent by cationic polymerization using a Lewis acid catalyst. According to the second polymerization step, a second polymer containing 60% by mass or more of an aliphatic monomer unit is formed in a state of being dissolved in the hydrocarbon solvent.

[0052] The production method of the present invention employs two polymerization steps, the first polymerization step and the second polymerization step, and therefore can obtain a first polymer containing 80% by mass or more of aromatic monomer units and a second polymer containing 60% by mass or more of aliphatic monomer units in the same polymerization system. Therefore, the production method of the present invention effectively solves the problems that arise when these polymers are obtained separately. Specifically, the problem of high melt viscosity and poor liquid transferability in a molten state when a first polymer containing a relatively large amount of aromatic monomer units is obtained alone, and the problem of proneness to blocking and therefore poor handleability when a second polymer containing a relatively large amount of aliphatic monomer units is obtained alone, can be effectively solved. This allows for high productivity while enabling improved low-temperature properties, adhesive strength, and holding power when a hot-melt pressure-sensitive adhesive composition is prepared, which are the effects of using the first polymer and the second polymer in combination.

[0053] In the present invention, polymerization in the first polymerization step may be carried out followed by polymerization in the second polymerization step, or conversely, polymerization in the second polymerization step may be carried out followed by polymerization in the first polymerization step. However, from the viewpoint of operability and controllability of the polymerization, a method in which polymerization in the first polymerization step is carried out followed by polymerization in the second polymerization step is preferred.

[0054] When polymerization in the first polymerization step is carried out followed by polymerization in the second polymerization step, the second monomer is polymerized by cationic polymerization using a Lewis acid catalyst in a polymerization system containing a first polymer containing aromatic monomer units in a proportion of 80% by mass or more, and as a result, a second polymer containing aliphatic monomer units in a proportion of 60% by mass or more is formed together with the first polymer in a state of being dissolved in a hydrocarbon solvent. Alternatively, when polymerization in the first polymerization step is carried out after polymerization in the two polymerization steps, the first monomer is polymerized by cationic polymerization using a Lewis acid catalyst in a polymerization system containing a second polymer containing aliphatic monomer units in a proportion of 60% by mass or more, and as a result, a first polymer containing aromatic monomer units in a proportion of 80% by mass or more is formed together with the second polymer in a state of being dissolved in a hydrocarbon solvent.

[0055] In the production method of the present invention, a part of the first polymer may be copolymerized with the second monomer, or a part of the second polymer may be copolymerized with the first monomer.

[0056] The second monomer used in the second polymerization step may contain an aliphatic monomer in a proportion of 60 mass% or more, more preferably 70 to 99.9 mass%, and even more preferably 80 to 99.8 mass%. If the proportion of the aliphatic monomer is too low, the resulting hot-melt pressure-sensitive adhesive composition will have poor low-temperature properties.

[0057] The second monomer may contain 60% by mass or more of an aliphatic monomer, but in the present invention, it is preferable to use one containing 1 to 60% by mass of a 1,3-pentadiene monomer, 1 to 30% by mass of an alicyclic monoolefin monomer having 4 to 6 carbon atoms, 0 to 65% by mass of an acyclic monoolefin monomer having 4 to 8 carbon atoms, 0 to 10% by mass of an alicyclic diolefin monomer, and 0 to 40% by mass of an aromatic monoolefin monomer. By containing these monomers in the above ranges, when a hot melt pressure-sensitive adhesive composition is prepared, it is possible to achieve more excellent low temperature properties.

[0058] The content of the 1,3-pentadiene monomer in the second monomer is preferably 1 to 60 mass%, more preferably 10 to 55 mass%, even more preferably 20 to 50 mass%, still more preferably 25 to 47 mass%, and particularly preferably 30 to 45 mass%.

[0059] The content of the alicyclic monoolefin monomer having 4 to 6 carbon atoms in the second monomer is preferably 1 to 30 mass%, more preferably 3 to 27 mass%, even more preferably 5 to 25 mass%, still more preferably 7 to 23 mass%, and particularly preferably 8 to 20 mass%.

[0060] The content of the acyclic monoolefin monomer having 4 to 8 carbon atoms in the second monomer is preferably 0 to 65 mass%, more preferably 20 to 61 mass%, even more preferably 30 to 59 mass%, and particularly preferably 36 to 57 mass%.

[0061] The content of the alicyclic diolefin monomer in the second monomer is preferably 0 to 10 mass %, more preferably 0.1 to 7 mass %, still more preferably 0.2 to 4 mass %, and particularly preferably 0.3 to 1 mass %.

[0062] The content of the aromatic monoolefin monomer in the second monomer is preferably 0 to 40 mass %, more preferably 0 to 30 mass %, further preferably 0 to 20 mass %, and particularly preferably 0 to 12 mass %.

[0063] The second monomer may also contain other monomers that form the above-mentioned other monomer units, and the content ratio of the other monomers is usually within the range of 0% by mass to 30% by mass, preferably 0% by mass to 25% by mass, and more preferably 0% by mass to 20% by mass.

[0064] The method of adding the second monomer to the polymerization system in the second polymerization step is not particularly limited, and may be a method of adding the second monomer to the polymerization system all at once at the start of polymerization, or a method of continuously adding the second monomer dropwise to the polymerization system. However, from the viewpoint of reaction temperature and controllability of polymerization, a method of continuously adding the second monomer dropwise to the polymerization system is preferred.

[0065] The amount of the second monomer used in the second polymerization step is preferably 65 to 99 parts by mass, more preferably 68 to 96 parts by mass, and even more preferably 70 to 93 parts by mass, relative to 100 parts by mass of the total amount of the monomers used in the polymerization (for example, the total amount of the first monomer used in the first polymerization step and the second monomer used in the second polymerization step). By setting the amount of the second monomer used within the above range, when a hot melt pressure-sensitive adhesive composition is prepared, it is possible to further improve the low temperature properties, adhesive strength, and holding power.

[0066] The softening point of the second polymer formed in the second polymerization step is not particularly limited, but is preferably 50 to 120°C, more preferably 60 to 100°C, and even more preferably 70 to 90°C. When the softening point is in the above range, the hot-melt pressure-sensitive adhesive composition can have better low-temperature performance. The softening point of the second polymer can be measured in accordance with JIS K 6863.

[0067] In addition, the second polymerization step is preferably carried out subsequent to the first polymerization step, and therefore, the Lewis acid catalyst, hydrocarbon solvent, and optionally the halogenated hydrocarbon used in the first polymerization step may be used as they are.

[0068] The polymerization temperature when carrying out the polymerization reaction in the second polymerization step is not particularly limited, but is preferably −20° C. to 100° C., more preferably 10° C. to 80° C. The polymerization reaction time may be appropriately selected, but is usually 10 minutes to 12 hours, preferably 30 minutes to 6 hours.

[0069] Then, in the second polymerization step, when a desired polymerization conversion rate is obtained, a polymerization terminator such as methanol, an aqueous sodium hydroxide solution, or an aqueous ammonia solution is added to the polymerization reaction system to terminate the polymerization, thereby obtaining a polymer solution containing the hydrocarbon resin.

[0070] Next, the resulting polymer solution containing the hydrocarbon resin is subjected to a treatment such as filtration to remove catalyst residues that are insoluble in the hydrocarbon solvent, if necessary, to obtain the hydrocarbon resin.

[0071] If necessary, the obtained hydrocarbon resin may be subjected to a hydrogenation reaction to hydrogenate the carbon-carbon double bonds in the hydrocarbon resin. The hydrogenation of the hydrocarbon resin can be carried out by contacting the hydrocarbon resin with hydrogen in the presence of a hydrogenation catalyst.

[0072] The hydrogenation catalyst is not particularly limited, but a nickel catalyst is preferred. In particular, from the viewpoint of high reactivity, a catalyst containing, as a main component, a compound in which nickel as a metal is supported on a supported inorganic compound as a support is preferred. Specific examples of the supported inorganic compound as a support include silica, alumina, boria, silica-alumina, diatomaceous earth, clay, magnesia, magnesia-silica (silica-magnesium oxide), titania, and zirconia. Among these, magnesia-silica is preferred from the viewpoint of reactivity.

[0073] <Hot melt adhesive composition> In the present invention, a hot melt pressure-sensitive adhesive composition can be prepared by blending a thermoplastic elastomer with the hydrocarbon resin obtained by the above-described production method of the present invention.

[0074] The thermoplastic elastomer is not particularly limited, and any thermoplastic elastomer used as a base polymer for hot-melt pressure-sensitive adhesives can be used without limitation. However, in terms of further enhancing the effects of the present invention, at least one selected from ethylene-vinyl acetate copolymer, styrene-based thermoplastic elastomer, and polyolefin-based thermoplastic elastomer is preferred.

[0075] The ethylene-vinyl acetate copolymer is not particularly limited, but preferably has a vinyl acetate monomer unit content of 10 to 50 mass%, more preferably 15 to 40 mass%, and even more preferably 15 to 35 mass%. Furthermore, the ethylene-vinyl acetate copolymer preferably has a melt flow rate of 1 to 500 g / 10 min.

[0076] The ethylene-vinyl acetate copolymer is commercially available, and examples thereof that can be suitably used include "EVAFLEX EV220 (product name)" manufactured by DuPont-Mitsui Polychemicals Co., Ltd. and "VA900 (product name)" manufactured by Lotte Chemical Co., Ltd.

[0077] The styrene-based thermoplastic elastomer is not particularly limited, and examples thereof include random, block, and graft copolymers of a styrene-based monomer with another monomer copolymerizable with the styrene-based monomer, hydrogenated products of such copolymers, and block copolymers containing at least one aromatic vinyl polymer block and at least one conjugated diene polymer block. Specific examples of such block copolymers that can be suitably used include styrene-isoprene diblock copolymers, styrene-isoprene-styrene triblock copolymers, isoprene-styrene-isoprene triblock copolymers, styrene-isoprene-styrene-isoprene tetrablock copolymers, and mixtures thereof.

[0078] Furthermore, the polyolefin-based thermoplastic elastomer is not particularly limited, but examples thereof include ethylene / α-olefin copolymers. The α-olefin copolymerized with ethylene to obtain the ethylene / α-olefin copolymer is not particularly limited, but examples thereof include α-olefins having 3 to 20 carbon atoms such as propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene, and are preferred, with α-olefins having 6 to 8 carbon atoms being more preferred, and 1-octene being even more preferred. The α-olefins may be used alone or in combination of two or more.

[0079] The content of α-olefin units in the ethylene / α-olefin copolymer is not particularly limited, but the proportion of α-olefin units relative to all monomer units is preferably 20 to 40 mol %. Furthermore, the ethylene / α-olefin copolymer that can be used preferably has a melt flow rate of 200 to 1500 g / 10 min.

[0080] The blending ratio of the thermoplastic elastomer to the hydrocarbon resin obtained by the production method of the present invention in the hot melt pressure-sensitive adhesive composition according to the present invention is not particularly limited, but the blending ratio of the hydrocarbon resin is preferably 50 to 500 parts by mass, more preferably 80 to 400 parts by mass, per 100 parts by mass of the thermoplastic elastomer. When the blending ratio of the hydrocarbon resin is within this range, the adhesive strength of the hot melt pressure-sensitive adhesive composition becomes particularly good.

[0081] The hot-melt adhesive composition according to the present invention may consist solely of the hydrocarbon resin and thermoplastic elastomer obtained by the production method of the present invention, but may also contain other components. Other components that may be contained in the hot-melt adhesive composition include waxes, softeners, antioxidants, tackifier resins other than the hydrocarbon resin obtained by the production method of the present invention, polymers other than those mentioned above, heat stabilizers, UV absorbers, fillers, and other compounding agents. It is preferable that the hot-melt adhesive composition is a solvent-free composition.

[0082] In obtaining the hot-melt pressure-sensitive adhesive composition according to the present invention, the method for mixing the hydrocarbon resin, thermoplastic elastomer, and other components added as necessary is not particularly limited, and examples thereof include a method in which each component is dissolved in a solvent and mixed uniformly, and then the solvent is removed by heating, or a method in which each component is melt-mixed using a kneader, etc. Among these methods, melt-mixing is preferred from the viewpoint of more efficient mixing. The temperature at which melt-mixing is performed is not particularly limited, but is usually in the range of 100 to 200°C.

[0083] The hot-melt adhesive composition according to the present invention contains the hydrocarbon resin obtained by the production method according to the present invention as a tackifying resin, and therefore has excellent low-temperature properties, adhesive strength, and holding power. Therefore, by taking advantage of these properties, the hot-melt adhesive composition according to the present invention can be used to bond a variety of members, and can achieve energy-saving, highly productive, and highly holding power bonding. The hot-melt adhesive composition according to the present invention is preferably used, for example, as an adhesive for various adhesive tapes and labels. Specifically, by forming an adhesive layer comprising the hot-melt adhesive composition according to the present invention on a sheet-like substrate constituting the adhesive tape or label, the hot-melt adhesive composition according to the present invention can be used as an adhesive tape or label comprising the substrate and an adhesive layer comprising the hot-melt adhesive composition according to the present invention. [Example]

[0084] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Note that "parts" and "%" are by mass unless otherwise specified. The test methods used in the present examples and comparative examples are as follows.

[0085] [Number average molecular weight (Mn), weight average molecular weight (Mw), Z average molecular weight (Mz), peak top molecular weight, and molecular weight distribution (Mw / Mn, Mz / Mw) of hydrocarbon resin] The hydrocarbon resins were analyzed by gel permeation chromatography to determine the number-average molecular weight (Mn), weight-average molecular weight (Mw), Z-average molecular weight (Mz), and peak-top molecular weight (Mw / Mn) in terms of standard polystyrene. Based on these results, the molecular weight distributions Mw / Mn and Mz / Mw were calculated. The gel permeation chromatography analysis was performed using a Tosoh HLC-8320GPC instrument and three Tosoh TSKgel SuperMultiporeHZ columns connected together. The analysis was performed at 40°C with a flow rate of 1.0 mL / min in tetrahydrofuran.

[0086] [Blocking property of hydrocarbon resin] The hydrocarbon resin was crushed into pieces of approximately 5 mm square to prepare multiple 30 g pieces of sample. These were placed in a 10 cm x 10 cm polyethylene bag, a 2 kg weight was placed on top, and the bag was kept at room temperature (23°C) for 12 hours. After this time, the blocking properties of the small sample pieces were evaluated according to the following criteria. ◯: No blocking occurred at all. ×: Blocking occurred.

[0087] [Melt viscosity of hydrocarbon resin] The hydrocarbon resin was melted by heating to 200°C, and the melt viscosity at a temperature of 200°C was measured using a Brookfield viscometer.

[0088] [Softening point of hydrocarbon resin] The hydrocarbon resin was measured in accordance with JIS K 6863.

[0089] [Peel strength of hot melt adhesive composition] The obtained hot-melt pressure-sensitive adhesive composition was melt-coated onto a 25 μm PET film to a thickness of 20 to 30 μm to obtain a coated sheet. This coated sheet was then cut into test pieces. Using the test pieces obtained in this way, the peel strength (N / m) at room temperature was evaluated in accordance with PSTC-101 (180° peel adhesion test by the US Adhesive Tape Committee) using a stainless steel plate as the adherend, by measuring at a tensile speed of 300 mm / min and a temperature of 23°C. The higher the value, the better the adhesive strength.

[0090] [Loop tack (23°C) of hot melt adhesive composition] Using test pieces obtained in the same manner as above, loop tack (N / 25 mm) at room temperature (23°C) was evaluated in accordance with PSTC-16 (loop tack test by the US Adhesive Tape Committee) using stainless steel plates as adherends, with measurements taken at a test speed of 300 mm / min, an adhesive joint size of 25 x 25 mm, and a temperature of 23°C. The higher the value, the better the initial adhesive strength.

[0091] [Loop tack (0°C) of hot melt adhesive composition] Using test pieces obtained in the same manner as above, loop tack (N / 25 mm) at low temperature (0°C) was evaluated in accordance with PSTC-16 (loop tack test by the US Adhesive Tape Committee) using stainless steel plates as adherends, with measurements taken at a test speed of 300 mm / min, an adhesive joint size of 25 x 25 mm, and a temperature of 0°C. The higher the value, the better the initial adhesive strength.

[0092] [Holding power of hot melt adhesive composition] Using test pieces obtained in the same manner as above, holding power was evaluated in accordance with PSTC-107 Procedure A (a holding power test method established by the US Adhesive Tape Committee) using stainless steel plates as adherends, with a bonded area of ​​10 x 25 mm, a load of 1000 ± 5 g, and a temperature of 50°C, by measuring the time (minutes) until peeling. The higher the value, the better the holding power.

[0093] [Glass transition temperature of hot melt adhesive composition] The glass transition temperature of the obtained hot melt pressure-sensitive adhesive composition was measured by a differential scanning calorimeter (DSC) at a temperature rise rate of 4°C / min and a frequency of 10 rad / s in the range of -40°C to 180°C. The measuring instrument used was ARES-G2 (manufactured by TA Instruments).

[0094] Example 1 A polymerization reactor was charged with 52.7 parts of cyclopentane as a hydrocarbon solvent, heated to 75°C, and then 1.0 parts of aluminum chloride was added. While maintaining the temperature at 75°C, 28.6 parts of a C9 fraction (containing 89.4% aromatic monomers and 10.6% dicyclopentadiene) were added dropwise over 15 minutes to polymerize the first monomer (first polymerization step). Next, 71.4 parts of a second monomer (containing 32.1% 1,3-pentadiene, 15.0% cyclopentene, 51.1% isobutylene, 1.2% diisobutylene, 0.1% dicyclopentadiene, and 0.5% C4-C6 unsaturated hydrocarbons) were added dropwise over 45 minutes to polymerize the second monomer (second polymerization step). During the polymerization, the second monomer was mixed with 15.3 parts of a C4-C6 saturated hydrocarbon and 0.5 parts of toluene as a hydrocarbon solvent to adjust the viscosity, and the mixture of the C4-C6 saturated hydrocarbon and toluene was added dropwise to the polymerization reactor. Aqueous sodium hydroxide solution was then added to the polymerization reactor to terminate the polymerization reaction. The precipitate formed upon termination of the polymerization was removed by filtration to obtain a polymer solution containing a hydrocarbon resin. The polymer solution was then transferred to a distillation kettle and heated at 250°C for 1 hour under a nitrogen atmosphere for stripping, thereby removing the hydrocarbon solvent and obtaining a solid hydrocarbon resin. The composition of the resulting hydrocarbon resin was approximately the same as the component ratios of the raw materials used to construct the hydrocarbon resin. The C9 fraction used in this example contained 13 to 17 mass% of styrene, 25 to 40 mass% of indene, 6 to 9 mass% of α-methylstyrene, 6 to 9 mass% of β-methylstyrene, 25 to 45 mass% of vinyltoluene, and 3 to 7 mass% of 1-methylindene (the same applies to Examples 2 to 6 and Comparative Examples 1, 2, and 4 described below). The number-average molecular weight (Mn), weight-average molecular weight (Mw), Z-average molecular weight (Mz), peak-top molecular weight, molecular weight distribution (Mw / Mn, Mz / Mw), and softening point of the obtained hydrocarbon resin were measured according to the above-mentioned methods, and the blocking property and melt viscosity were also evaluated. The results are shown in Table 1.

[0095] Examples 2 to 6 The hydrocarbon resins of Examples 2 to 6 were obtained by polymerization in the same manner as in Example 1, except that a C9 fraction having the monomer composition shown in Table 1 was used as the first monomer, a monomer mixture having the monomer composition shown in Table 1 was used as the second monomer, the amounts of the first monomer and the second monomer used were shown in Table 1, the amount of aluminum chloride used was shown in Table 1, and the polymerization temperature was shown in Table 1. The obtained hydrocarbon resins were then subjected to various measurements and evaluations in the same manner as in Example 1. The results are shown in Table 1.

[0096] Comparative Example 1 Polymerization procedures were carried out in the same manner as in Example 1 to obtain the hydrocarbon resins of Comparative Example 1, except that a C9 fraction having the monomer composition shown in Table 1 was used as the first monomer, a monomer mixture having the monomer composition shown in Table 1 was used as the second monomer, and the amounts of the first monomer and the second monomer used were as shown in Table 1. The hydrocarbon resins obtained were then subjected to various measurements and evaluations in the same manner as in Example 1. The results are shown in Table 1.

[0097] Comparative Example 2 A polymerization reactor was charged with 52.7 parts of cyclopentane as a hydrocarbon solvent and heated to 75°C. After adding 1.0 parts of aluminum chloride, the temperature was maintained at 75°C. Then, 100 parts of a monomer mixture having the monomer composition shown in Table 1 (listed as the second monomer in Table 1; the C9 fraction is shown as the amount of aromatic monomer in the C9 fraction) were continuously added dropwise over 60 minutes to carry out polymerization. For viscosity adjustment, the monomer mixture was mixed with 15.3 parts of a C4-C6 saturated hydrocarbon and 0.5 parts of toluene as a hydrocarbon solvent, and the resulting mixture of C4-C6 saturated hydrocarbon and toluene was added dropwise to the polymerization reactor. The polymerization reaction was then terminated by adding aqueous sodium hydroxide to the polymerization reactor. The precipitate formed during the polymerization termination was removed by filtration to obtain a polymer solution containing a hydrocarbon resin. The polymer solution was then transferred to a distillation still and heated at 250°C for 1 hour under a nitrogen atmosphere to perform a stripping operation, thereby removing the hydrocarbon solvent and obtaining a solid hydrocarbon resin. The composition of the obtained hydrocarbon resin was approximately the same as the component ratio of the raw materials used to form the hydrocarbon resin. The obtained hydrocarbon resin was then subjected to various measurements and evaluations in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 2 corresponds to an experimental example in which a first monomer containing an aromatic monomer in a proportion of 80% by mass or more and a second monomer containing an aliphatic monomer in a proportion of 60% by mass or more were polymerized in the same polymerization step, rather than in separate polymerization steps, without going through two polymerization steps consisting of a first polymerization step and a second polymerization step.

[0098] Comparative Example 3 Polymerization procedures were carried out in the same manner as in Example 1, except that a monomer mixture having the monomer composition shown in Table 1 was used as the monomer, to obtain the hydrocarbon resins of Comparative Example 1. The obtained hydrocarbon resins were then subjected to various measurements and evaluations in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 3 corresponds to an experimental example in which only a second monomer containing an aliphatic monomer in a proportion of 60% by mass or more was polymerized without going through the two-stage polymerization process of the first polymerization process and the second polymerization process.

[0099] Comparative Example 4 A polymerization reactor was charged with 52.7 parts of cyclopentane as a hydrocarbon solvent and heated to 75°C. After adding 1.0 parts of aluminum chloride, the temperature (75°C) was maintained. Then, 100 parts of a C9 fraction (containing 89.4% aromatic monomers and 10.6% dicyclopentadiene, listed as the first monomer in Table 1) was continuously added dropwise over 60 minutes to the reactor to conduct polymerization. During the polymerization, the C9 fraction was mixed with 15.3 parts of a C4-C6 saturated hydrocarbon and 0.5 parts of toluene as a hydrocarbon solvent to adjust the viscosity. The mixture of the C4-C6 saturated hydrocarbon and toluene was then added dropwise to the polymerization reactor. The polymerization reaction was then terminated by adding aqueous sodium hydroxide to the reactor. The precipitate formed during the polymerization termination was removed by filtration to obtain a polymer solution containing a hydrocarbon resin. The polymer solution was then transferred to a distillation still and heated at 250°C for 1 hour under a nitrogen atmosphere to perform a stripping operation, thereby removing the hydrocarbon solvent and obtaining a solid hydrocarbon resin. The composition of the obtained hydrocarbon resin was approximately the same as the component ratio of the raw materials used to form the hydrocarbon resin. The obtained hydrocarbon resin was then subjected to various measurements and evaluations in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 4 corresponds to an experimental example in which only the first monomer containing 80% by mass or more of aromatic monomer was polymerized without going through the two-stage polymerization process of the first polymerization process and the second polymerization process.

[0100] Example 1A 100 parts of a styrene-isoprene-styrene block copolymer (trade name "Quintac® 3421" manufactured by Nippon Zeon Co., Ltd.) were placed in a mixing blade kneader, to which 100 parts of the hydrocarbon resin obtained in Example 1, 10 parts of a softener (trade name "Sunpure N100" naphthenic process oil manufactured by Nippon San Oil Co., Ltd.), and 1.5 parts of an antioxidant (trade name "Irganox 1010" manufactured by BASF) were added. The system was then purged with nitrogen gas, and the mixture was kneaded at 160 to 180°C for 1 hour to prepare a hot-melt pressure-sensitive adhesive composition. The resulting hot-melt pressure-sensitive adhesive composition was then measured for peel strength, loop tack (at 23°C and 0°C), holding power, and glass transition temperature. The results are shown in Table 2.

[0101] Examples 2A to 6A Hot melt pressure-sensitive adhesive compositions were prepared in the same manner as in Example 1, except that 100 parts of the hydrocarbon resins obtained in Examples 2 to 6 were used instead of 100 parts of the hydrocarbon resin obtained in Example 1, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0102] [Comparative Examples 1A to 3A] Hot melt pressure-sensitive adhesive compositions were prepared in the same manner as in Example 1, except that 100 parts of the hydrocarbon resins obtained in Comparative Examples 1 to 3 were used instead of 100 parts of the hydrocarbon resin obtained in Example 1, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0103] [Table 1]

[0104] [Table 2]

[0105] As shown in Table 1, when a first monomer containing an aromatic monomer in a proportion of 80 mass% or more was polymerized in the first polymerization step, and a second monomer containing an aliphatic monomer in a proportion of 60 mass% or more was polymerized in the second polymerization step, and the proportion of the first monomer used was 1 to 35 mass% relative to the total amount of monomers used in the polymerization, the resulting hydrocarbon resin was inhibited in blocking and had a low melt viscosity at 200°C. Furthermore, the hot-melt pressure-sensitive adhesive composition obtained using such a hydrocarbon resin had excellent loop tack at 0°C, excellent low-temperature properties, and also excellent adhesive strength and holding power (Examples 1 to 6 and Examples 1A to 6A). The hydrocarbon resins obtained in Examples 1 to 6 were separately polymerized to form a first polymer in a first polymerization step and a second polymer in a second polymerization step, and their softening points were measured in accordance with JIS K 6863 (using an ASP-5 (manufactured by TANAKA) as the measuring device). The softening point of the first polymer formed in the first polymerization step was in the range of 150 to 170°C, and the softening point of the second polymer formed in the second polymerization step was in the range of 65 to 85°C.

[0106] On the other hand, when the two-stage polymerization process of the first polymerization process and the second polymerization process was carried out, but the proportion of the first monomer used in the first polymerization process was too high, the obtained hot-melt pressure-sensitive adhesive composition had low loop tack at 0°C and was poor in low-temperature properties (Comparative Example 1, Comparative Example 1A). When a first monomer containing 80% by mass or more of an aromatic monomer and a second monomer containing 60% by mass or more of an aliphatic monomer are polymerized in the same polymerization step, rather than in separate polymerization steps, without going through the two-stage polymerization steps of the first polymerization step and the second polymerization step, the first monomer and the second monomer are copolymerized, and as a result, the obtained hot melt pressure-sensitive adhesive composition has low loop tack at 0°C, poor low-temperature properties, and also poor holding power (Comparative Example 2, Comparative Example 2A). Furthermore, when only the second monomer containing 60 mass % or more of an aliphatic monomer was polymerized without going through the two-stage polymerization process of the first polymerization step and the second polymerization step, the resulting hydrocarbon resin was prone to blocking, and furthermore, the hot-melt pressure-sensitive adhesive composition obtained using this was inferior in adhesive strength and holding power (Comparative Example 3, Comparative Example 3A). Furthermore, when only the first monomer containing 80% by mass or more of aromatic monomer was polymerized without going through the two-stage polymerization process of the first polymerization process and the second polymerization process, the resulting hydrocarbon resin had a significantly high melt viscosity at 200°C (Comparative Example 4).

Claims

1. 1. A method for producing a hydrocarbon resin, comprising a step of polymerizing a monomer by cationic polymerization in a hydrocarbon solvent using a Lewis acid catalyst, a first polymerization step of polymerizing a first monomer containing an aromatic monomer in a proportion of 80% by mass or more and further containing dicyclopentadiene; a second polymerization step of polymerizing a second monomer containing an aliphatic monomer in a proportion of 60% by mass or more, A method for producing a hydrocarbon resin, wherein the proportion of the first monomer used in the first polymerization step is 1 to 35 mass % based on the total amount of monomers used in polymerization.

2. 2. The method for producing a hydrocarbon resin according to claim 1, wherein the first monomer comprises at least one selected from the group consisting of a styrene compound, an indene compound, and a C9 fraction.

3. The second monomer is 1 to 60% by mass of 1,3-pentadiene monomer, 1 to 30% by mass of an alicyclic monoolefin monomer having 4 to 6 carbon atoms, 0 to 65% by mass of an acyclic monoolefin monomer having 4 to 8 carbon atoms, 0 to 10% by weight of an alicyclic diolefin monomer, and The method for producing a hydrocarbon resin according to claim 1 or 2, wherein the hydrocarbon resin contains 0 to 40% by mass of an aromatic monoolefin monomer.

4. the softening point of the first polymer formed by polymerization in the first polymerization step is 140 to 200°C; 4. The method for producing a hydrocarbon resin according to claim 1, wherein the second polymer formed by polymerization in the second polymerization step has a softening point of 50 to 120°C.

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