Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F297/00—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer
  • C08F297/02—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer using a catalyst of the anionic type
  • C08F297/04—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer using a catalyst of the anionic type polymerising vinyl aromatic monomers and conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F236/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
  • C08F236/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
  • C08F236/04—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
  • C08F236/10—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated with vinyl-aromatic monomers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/04—Reduction, e.g. hydrogenation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L53/02—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
  • C09J11/08—Macromolecular additives
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J153/00—Adhesives based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
  • C09J153/02—Vinyl aromatic monomers and conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J153/00—Adhesives based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
  • C09J153/02—Vinyl aromatic monomers and conjugated dienes
  • C09J153/025—Vinyl aromatic monomers and conjugated dienes modified

Definitions

• the present invention relates to an adhesive composition and a method for producing an adhesive composition.
• Patent Document 1 describes an adhesive composition made of a block copolymer containing a polystyrene block and a polyfarnesene block. The ⁇ -farnesene used to form the polyfarnesene block is obtained by fermenting sugars from sugarcane, and therefore the biomass ratio of the adhesive composition can be increased.
• the adhesive compositions may be required to have high heat resistance in addition to adequate adhesive properties. For this reason, there is still room for improvement in the adhesive compositions made of the above-mentioned block copolymers.
• the object of the present invention is to provide an adhesive composition that has a high degree of bio-based content, and also has suitable adhesive properties and high heat resistance, and a method for producing the same.
• the present inventors have found that in a pressure-sensitive adhesive composition containing a block copolymer (X) including a polymer block (A) containing a structural unit derived from an aromatic vinyl compound and a polymer block (B) containing a structural unit derived from a conjugated diene compound, and a tackifier (Y), the above-mentioned problems can be solved by specifying the structural unit derived from the conjugated diene compound in the polymer block (B), and have thus completed the present invention.
• a block copolymer (X) including a polymer block (A) containing a structural unit derived from an aromatic vinyl compound and a polymer block (B) containing a structural unit derived from a conjugated diene compound, and a tackifier (Y)
• the block copolymer (X) contains, as the polymer block (B), at least one polymer block (B-1) containing a structural unit derived from ⁇ -farnesene,
• a liquid rubber component (Za) further comprising a liquid rubber component (Za), the liquid rubber component (Za) comprising at least one selected from the group consisting of an unhydrogenated liquid rubber (Za0) which is a non-hydrogenated liquid rubber, and a hydrogenated liquid rubber (Za1) which is a hydrogenated liquid rubber and has a hydrogenation rate of 90 mol% or less.
• SAFT shear fracture temperature
• a method for producing a pressure-sensitive adhesive composition comprising the steps of: (I) a step of dissolving the block copolymer (X) and the tackifier (Y) in a solvent and then distilling off the solvent, or (II) A method for producing a pressure-sensitive adhesive composition, comprising a step of melt-kneading a block copolymer (X) and a tackifier (Y).
• the present invention provides an adhesive composition that has a high bio-based content, as well as suitable adhesive properties and high heat resistance, and a method for producing the same.
• XX to YY means “at least XX and at most YY.”
• the lower limit and upper limit described in stages for the preferred numerical range e.g., range of content, etc.
• the description "preferably 10 to 90, more preferably 30 to 60” can be combined with the “preferable lower limit (10)” and the “more preferable upper limit (60)” to form “10 to 60.”
• the pressure-sensitive adhesive composition comprises a block copolymer (X) including a polymer block (A) containing a structural unit derived from an aromatic vinyl compound and a polymer block (B) containing a structural unit derived from a conjugated diene compound, and a tackifier (Y).
• the block copolymer (X) comprises at least one polymer block (B-1) containing a structural unit derived from ⁇ -farnesene as the polymer block (B).
• the block copolymer (X) comprises at least one selected from the group consisting of an unhydrogenated block copolymer (X0) which is a block copolymer that has not been hydrogenated, and a hydrogenated block copolymer (X1) which is a block copolymer that has been hydrogenated and has a hydrogenation rate of less than 50 mol%.
• the adhesive composition can have a high bio-based content because the polymer block (B) contained in the block copolymer (X) contains at least one polymer block (B-1) containing a structural unit derived from ⁇ -farnesene. Furthermore, by containing the polymer block (B-1) containing a structural unit derived from ⁇ -farnesene, the block copolymer (X) has a low viscosity and is flexible, and the adhesive composition containing the block copolymer can easily conform to the unevenness of an adherend.
• the block copolymer (X) contains at least one selected from the group consisting of unhydrogenated block copolymer (X0), which is a block copolymer that has not been hydrogenated, and hydrogenated block copolymer (X1), which is a block copolymer that has been hydrogenated and has a hydrogenation rate of less than 50 mol%. Therefore, the block copolymer (X) has many double bonds, has high crosslinkability, and can be easily crosslinked with a small amount of energy rays such as ultraviolet light (UV).
• UV ultraviolet light
• the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol% are considered to be involved in the crosslinking reaction due to the branched double bonds, and therefore have higher reactivity than, for example, hydrogenated block copolymers having a hydrogenation rate of 50 mol% or more. Therefore, crosslinking can increase the heat resistance of the adhesive composition and ensure appropriate adhesiveness.
• the pressure-sensitive adhesive composition may contain only the block copolymer (X) and the tackifier (Y), or may contain the block copolymer (X), the tackifier (Y) and other components.
• the total content of the block copolymer (X) and the tackifier (Y) in the adhesive composition is preferably 50 mass% or more, more preferably 60 mass% or more, and even more preferably 70 mass% or more, based on the total mass of the adhesive composition. Also, it may be 100 mass% or less, 95 mass% or less, or 90 mass% or less.
• the total content of the block copolymer (X) and the tackifier (Y) in the adhesive composition is preferably 50 to 100 mass% based on the total mass of the adhesive composition.
• a method can be used in which the pressure-sensitive adhesive composition is dissolved in an appropriate solvent, coated on an appropriate support or adherend, and dried to form a coating film.
• the pressure-sensitive adhesive composition can also be used as a hot-melt pressure-sensitive adhesive composition. In this case, the pressure-sensitive adhesive composition is heated to reduce the viscosity and then supplied onto the first adherend, or the pressure-sensitive adhesive composition is placed on the first adherend and then heated to reduce the viscosity, and then a second adherend is placed on top of the pressure-sensitive adhesive composition, thereby adhesively adhering the two adherends.
• the block copolymer (X) contains a polymer block (A) containing a structural unit derived from an aromatic vinyl compound and a polymer block (B) containing a structural unit derived from a conjugated diene compound.
• the block copolymer (X) contains at least one polymer block (B-1) containing a structural unit derived from ⁇ -farnesene as the polymer block (B). Therefore, the biobased degree of the pressure-sensitive adhesive composition can be increased compared to a case where the polymer block (B-1) is not contained.
• the polymer block (B-1) contains a structural unit derived from ⁇ -farnesene, and this ⁇ -farnesene has a bulky side chain, it is considered that entanglement between molecules is reduced, resulting in a lower viscosity and an increased affinity between the tackifier (Y) and the block copolymer (X).
• the pressure-sensitive adhesive composition can contain the tackifier (Y) at a high content ratio.
• the polymer block (B) will be described in detail later.
• the block copolymer (X) contains at least one selected from the group consisting of the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol %, and may further contain a hydrogenated block copolymer having a hydrogenation rate of 50 mol % or more in order to adjust the hydrogenation rate.
• the block copolymer (X) consists essentially of the unhydrogenated block copolymer (X0), or consists essentially of the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%, or consists essentially of both the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%, and it is more preferable that the block copolymer (X) consists essentially of the unhydrogenated block copolymer (X0).
• the term “substantially” means that in addition to an embodiment consisting of only the unhydrogenated block copolymer (X0) and an embodiment consisting of only the hydrogenated block copolymer (X1), the embodiment may also include an embodiment containing a component, such as a hydrogenated block copolymer having a hydrogenation rate of 50 mol % or more, which is inevitably present in the process of producing the block copolymer.
• the block copolymer (X) contains both the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%, from the viewpoint of facilitating obtaining the desired physical properties, it is preferable that the unhydrogenated block copolymer used to obtain the latter is the same as the former. However, as long as the effects of the present invention are not impaired, for example, an unhydrogenated block copolymer having a molecular weight different from that of the former or an unhydrogenated block copolymer having a structural unit different from that of the former may be used as the unhydrogenated block copolymer to obtain the latter.
• the content is not particularly limited, but from the viewpoint of making it easier to adjust the hydrogenation rate while ensuring the desired performance of the block copolymer (X), the content is preferably 0 to 60 mass %, more preferably 0 to 50 mass %, based on the mass of the block copolymer (X).
• the glass transition temperature (Tg) of the block copolymer (X) is preferably -52°C or lower, more preferably -54°C or lower, and even more preferably -57°C or lower, from the viewpoint of easily ensuring the cold resistance of the adhesive composition and the adhesive strength during high-speed peeling.
• block copolymer (X) The components constituting the block copolymer (X) are described below, but unless otherwise specified, these descriptions apply to both the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1).
• the polymer block (A) contains a structural unit derived from an aromatic vinyl compound (hereinafter, sometimes referred to as an "aromatic vinyl compound unit").
• aromatic vinyl compounds include styrene, ⁇ -methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, 1-vinylnaphthalene, 2-vinylnaphthalene, vinylanthracene, N,N-diethyl-4-amino
• the polymer block (A) may contain structural units derived from monomers other than aromatic vinyl compounds, for example, other monomers such as the monomers constituting the polymer block (B) described below.
• the content of aromatic vinyl compound units in the polymer block (A) is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass.
• the upper limit of the content of aromatic vinyl compound units in the polymer block (A) may be 100% by mass, 99% by mass, or 98% by mass.
• the content of aromatic vinyl compound units in the polymer block (A) is preferably 60 to 100% by mass.
• the block copolymer (X) may have at least one of the polymer blocks (A).
• the polymer blocks (A) may be the same or different.
• "polymer blocks are different" means that at least one of the monomer units constituting the polymer blocks, the weight average molecular weight, the stereoregularity, and, when a plurality of monomer units are present, the ratio of each monomer unit and the form of copolymerization (random, Taber, block) is different.
• the block copolymer (X) preferably has two or more polymer blocks (A).
• the content of the polymer block (A) in the block copolymer (X) (when a plurality of polymer blocks (A) are present, the total content thereof) is preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less, from the viewpoint of flexibility, and is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more, from the viewpoint of the balance between adhesive strength and heat resistance.
• the content of the polymer block (A) in the block copolymer (X) is preferably 3 to 35% by mass.
• the content of the polymer block (A) in the block copolymer (X) is a value determined by 1 H-NMR measurement, more specifically, a value measured according to the method described in the examples.
• the weight average molecular weight (Mw) of the polymer block (A) is preferably 3,000 to 60,000, more preferably 4,000 to 50,000, even more preferably 5,000 to 40,000, still more preferably 5,500 to 30,000, and even more preferably 6,000 to 20,000, from the viewpoints of coatability and heat resistance.
• the weight average molecular weight (Mw) of the polymer block (A) can be adjusted to the above range, for example, by adjusting the amount of the aromatic vinyl compound relative to the polymerization initiator used in the polymerization.
• weight average molecular weights are weight average molecular weights calculated using standard polystyrene standards and determined by gel permeation chromatography (GPC). The detailed measurement method can be as described in the Examples.
• the polymer block (B) contains a structural unit derived from a conjugated diene compound (hereinafter, may be abbreviated as a "conjugated diene compound unit").
• the block copolymer (X) used in the present invention contains, as the polymer block (B), at least one polymer block (B-1) containing a structural unit derived from ⁇ -farnesene.
• the block copolymer (X) used in the present invention may further contain, as the polymer block (B), in addition to the polymer block (B-1), a polymer block (B-2) which contains a structural unit derived from a conjugated diene compound other than ⁇ -farnesene and does not contain a structural unit derived from ⁇ -farnesene.
• the polymer blocks (B-1) and (B-2) will be described in detail later.
• the total content of structural units derived from ⁇ -farnesene in polymer block (B) is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, from the viewpoint of suppressing crystallization of polymer block (B) and ensuring strength.
• the total content of structural units derived from ⁇ -farnesene in polymer block (B) is preferably 10 to 100% by mass.
• the polymer block (B) may contain a structural unit derived from ⁇ -farnesene and a structural unit derived from at least one selected from the group consisting of butadiene, isoprene, and myrcene.
• the block copolymer (X) may contain the above-mentioned polymer block (B-1) and polymer block (B-2), and the polymer block (B-2) may contain a structural unit derived from at least one selected from the group consisting of butadiene, isoprene, and myrcene, or
• the polymer block (B-1) may contain a structural unit derived from ⁇ -farnesene and a structural unit derived from at least one selected from the group consisting of butadiene, isoprene, and myrcene.
• the content of conjugated diene compound units in the total amount of polymer block (B) is, from the viewpoint of flexibility and bio-based degree, preferably 60 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, particularly preferably 90 mass% or more, and most preferably substantially 100 mass%. There is no particular upper limit, and it may be 100 mass%, 99 mass%, or 98 mass%. In other words, the content of conjugated diene compound units in the total amount of polymer block (B) is preferably 60 to 100 mass%.
• the content of the conjugated diene compound unit in the total amount of polymer block (B) is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 65 mol% or more, still more preferably 80 mol% or more, particularly preferably 90 mol% or more, and most preferably substantially 100 mol%.
• the upper limit of the content of the conjugated diene compound unit in the total amount of polymer block (B) may be 100 mol%, 99 mol%, or 98 mol%. In other words, the content of the conjugated diene compound unit in the total amount of polymer block (B) is preferably 30 to 100 mol%.
• the mixing ratio of the conjugated diene compounds in the entire polymer block (B) [ ⁇ -farnesene/conjugated diene compounds other than ⁇ -farnesene] is not particularly limited as long as it does not impair the effects of the present invention, but from the viewpoint of increasing the biobased degree and reducing the viscosity, it is preferably 3/97 to 100/0, more preferably 40/60 to 100/0, even more preferably 50/50 to 100/0, even more preferably 70/30 to 100/0, even more preferably 80/20 to 100/0, even more preferably 85/15 to 100/0, and particularly preferably 90/10 to 100/0.
• the cohesive force is preferably 3/97 to 90/10, more preferably 5/95 to 85/15, even more preferably 10/90 to 45/55, and particularly preferably 15/85 to 40/60.
• the ratio may be 25/75 to 65/35, or 30/70 to 60/40.
• the polymer block (B) may contain structural units derived from other polymerizable monomers other than the conjugated diene compound.
• the content of structural units derived from other polymerizable monomers other than the conjugated diene compound in the polymer block (B) is preferably 70 mol% or less, more preferably 50 mol% or less, even more preferably 35 mol% or less, even more preferably 20 mol% or less, and particularly preferably 10 mol% or less.
• the lower limit of the content of structural units derived from other polymerizable monomers other than the conjugated diene compound but it may be 0 mol% or 5 mol%.
• the content of structural units derived from other polymerizable monomers other than the conjugated diene compound in the polymer block (B) is preferably 0 to 70 mol%.
• the total weight average molecular weight of the polymer blocks (B) in the block copolymer (X) is preferably 30,000 to 300,000, more preferably 40,000 to 250,000, and even more preferably 50,000 to 200,000, before hydrogenation, from the viewpoints of coatability, heat resistance, and the like.
• the polymer block (B-1) contains a structural unit (b11) derived from ⁇ -farnesene (hereinafter, sometimes simply referred to as "structural unit (b11)").
• the content of the structural unit (b11) in the polymer block (B-1) is preferably 1 to 100% by mass. Since the structural unit (b11) has a long and bulky side chain in the molecule, the polymer block (B-1) contains the structural unit (b11), and thus the flexibility of the block copolymer (X) is improved.
• the content of the structural unit (b11) in the polymer block (B-1) is more preferably 10 to 100% by mass, even more preferably 20 to 100% by mass, even more preferably 30 to 100% by mass, particularly preferably 50 to 100% by mass, and most preferably 100% by mass, i.e., the polymer block (B-1) is composed only of the structural unit (b11).
• the polymer block (B-1) is composed only of the structural unit (b11).
• ⁇ -farnesene is bio-derived, the amount of conjugated diene compounds other than ⁇ -farnesene, such as petroleum-derived butadiene and isoprene, used can be suppressed, thereby reducing dependency on petroleum.
• the content of the structural unit (b11) in the polymer block (B-1) is preferably 50 to 100 mass%, more preferably 60 to 100 mass%, even more preferably 70 to 100 mass%, and even more preferably 80 to 100 mass%.
• the content of the structural unit (b11) in the polymer block (B-1) is preferably from 1 to 99 mass%, more preferably from 10 to 99 mass%, even more preferably from 20 to 99 mass%, still more preferably from 30 to 99 mass%, and particularly preferably from 50 to 99 mass%.
• the polymer block (B-1) may contain a structural unit (b12) (hereinafter, also simply referred to as "structural unit (b12)”) derived from a conjugated diene compound other than ⁇ -farnesene, and the content of the structural unit (b12) in the polymer block (B-1) is preferably 0 to 99 mass%.
• a conjugated diene compound having no farnesene skeleton is preferable, and examples thereof include isoprene, butadiene, 2,3-dimethyl-butadiene, 2-phenyl-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, myrcene, and chloroprene. These may be used alone or in combination of two or more.
• the content of the structural unit (b12) is more preferably 90% by mass or less, even more preferably 80% by mass or less, even more preferably 70% by mass or less, and particularly preferably 50% by mass or less.
• the polymer block (B-1) may contain structural units other than the structural unit (b11) and the structural unit (b12).
• the total content of the structural unit (b11) and the structural unit (b12) in the polymer block (B-1) is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 100% by mass.
• the weight average molecular weight (Mw) of the polymer block (B-1) is preferably 30,000 to 300,000, more preferably 40,000 to 250,000, and even more preferably 50,000 to 200,000, from the viewpoints of coatability and heat resistance.
• the block copolymer (X) used in the present invention may contain only the polymer block (B-1) as the polymer block (B), or may further contain the polymer block (B-2) described below.
• the content of the polymer block (B-1) in the entire polymer block (B) is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, based on the mass of the entire polymer block (B), from the viewpoint of dispersibility of the tackifier (Y).
• Y dispersibility of the tackifier
• the content of the polymer block (B-1) in the entire polymer block (B) is preferably 50 to 100% by mass.
• the block copolymer (X) may further contain, as the polymer block (B), a polymer block (B-2) containing a structural unit (b22) described below, in addition to the polymer block (B-1).
• the polymer block (B-2) does not contain a structural unit derived from ⁇ -farnesene. That is, the polymer block (B-2) has a content of the structural unit (b21) derived from ⁇ -farnesene (hereinafter, also simply referred to as "structural unit (b21)”) of 0 mass %.
• Conjugated diene compounds constituting the structural unit (b22) (hereinafter also simply referred to as "structural unit (b22)") derived from a conjugated diene compound other than ⁇ -farnesene include the same conjugated diene compounds constituting the structural unit (b12) described above, and preferably include isoprene, butadiene, and myrcene. Of these, isoprene and butadiene are more preferred. These may be used alone or in combination of two or more. Furthermore, polymer block (B-2) may contain structural units other than the structural unit (b22).
• the content of the structural unit (b22) in the polymer block (B-2) is more preferably 60 to 100% by mass, even more preferably 80 to 100% by mass, even more preferably 90 to 100% by mass, and particularly preferably 100% by mass.
• the weight average molecular weight of the polymer block (B-2) is preferably 4,000 to 200,000, more preferably 4,500 to 150,000, and even more preferably 5,000 to 100,000.
• the block copolymer (X) contains at least one polymer block (A) and at least one polymer block (B).
• the bonding form of the polymer block (A) and the polymer block (B) is not particularly limited, and may be linear, branched, radial, or a combination of two or more thereof. Among these, a form in which each block is bonded linearly is preferred. Examples of the linear bonding form include bonding forms represented by (A-B) l , A-(B-A) m , or B-(A-B) n , where A represents polymer block (A) and B represents polymer block (B), where l, m, and n each independently represent an integer of 1 or more.
• the block copolymer (X) contains at least one each of the polymer block (A) and the polymer block (B-1), it is preferable that the block copolymer (X) is a triblock copolymer represented by A-B1-A, which has a bonding form having blocks in the order of the polymer block (A), the polymer block (B-1), and the polymer block (A) in this order. That is, the block copolymer (X) is preferably a triblock copolymer represented by A-B1-A.
• the bonding form of the multiple polymer blocks is not particularly limited and may be linear, branched, radial, or a combination of two or more thereof. Among these, a form in which the blocks are bonded linearly is preferred.
• the block copolymer (X) preferably has a structure having the polymer block (B-1), the polymer block (A), and the polymer block (B-2) in this order (ie, a structure of B1-A-B2).
• the block copolymer (X) is preferably a tetrablock copolymer represented by B1-A-B2-A, a pentablock copolymer represented by B1-A-B2-A-B1, or a copolymer represented by B1-A-(B2-A) p -B1, B1-A-(B2-A-B1) q , or B1-(A-B2-A-B1) r (p, q, and r each independently represent an integer of 2 or more), and among these, a pentablock copolymer represented by B1-A-B2-A-B1 is more preferable.
• the block copolymer (X) contains the polymer block (B-1) and the polymer block (B-2) as the polymer block (B), the block copolymer (X) is preferably a pentablock copolymer represented by B1-A-B2-A-B1.
• a polymer block that should strictly be expressed as A-X-A (X represents a coupling agent residue) is expressed as A as a whole. Since this type of polymer block containing a coupling agent residue is treated as above in this specification, for example, a block copolymer that contains a coupling agent residue and should strictly be expressed as B1-A-B2-X-B2-A-B1 is expressed as B1-A-B2-A-B1 and is treated as an example of a pentablock copolymer.
• the two or more polymer blocks (A) in the above-mentioned block copolymer (X) may each be a polymer block consisting of the same structural units or different structural units.
• each polymer block may each be a polymer block consisting of the same structural units or different structural units.
• the type of aromatic vinyl compound in each may be the same or different.
• the mass ratio of the polymer block (A) to the polymer block (B-1) [(A)/(B-1)] is preferably 1/99 to 70/30, more preferably 5/95 to 60/40, even more preferably 10/90 to 50/50, still more preferably 15/85 to 40/60, and even more preferably 15/85 to 35/65.
• a pressure-sensitive adhesive composition having good pressure-sensitive adhesive strength and a high bio-based degree can be obtained.
• the mass ratio of the polymer block (A) to the polymer block (B-1) [(A)/(B-1)] is preferably 1/99 to 70/30, more preferably 5/95 to 60/40, even more preferably 10/90 to 50/50, even more preferably 20/80 to 40/60, and even more preferably 25/75 to 35/65. Within this range, a pressure-sensitive adhesive composition having excellent pressure-sensitive adhesive strength and cohesive strength can be obtained.
• the mass ratio of the polymer block (A) to the total amount of the polymer block (B-1) and the polymer block (B-2) [(A)/((B-1)+(B-2)] is preferably 1/99 to 70/30. Within this range, a pressure-sensitive adhesive composition having an excellent balance between viscosity and elasticity is easily obtained. From this viewpoint, the mass ratio [(A)/((B-1)+(B-2)] is more preferably 1/99 to 60/40, even more preferably 10/90 to 40/60, even more preferably 10/90 to 30/70, and even more preferably 15/85 to 25/75.
• the block copolymer (X) contains polymer block (A), polymer block (B-1) and polymer block (B-2)
• the total content of the structural unit (b11) and the structural unit (b21) relative to the total amount of the polymer block (B-1) and the polymer block (B-2) in the block copolymer [((b11)+(b21))/((B-1)+(B-2)] is preferably 40-90% by mass, more preferably 50-80% by mass, and even more preferably 60-70% by mass, from the viewpoint of flexibility.
• the total content of the polymer block (A) and the polymer block (B-1) in the block copolymer (X) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass. That is, the total content of the polymer block (A) and the polymer block (B-1) in the block copolymer (X) is, for example, 80 to 100% by mass.
• the total content of these polymer blocks (A), (B-1) and (B-2) in the block copolymer (X) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass. That is, the total content of the polymer blocks (A), (B-1) and (B-2) in the block copolymer (X) is, for example, 80 to 100% by mass.
• the content of polymer block (B-2) in the entire polymer block (B) is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, based on the mass of the entire polymer block (B), from the viewpoint of suppressing a decrease in the dispersibility of tackifier (Y). It may also be 10% by mass or more, or 20% by mass or more, but is preferably 0% by mass. In other words, the content of polymer block (B-1) in the entire polymer block (B) is preferably 0 to 50% by mass.
• the bond form of the conjugated diene compound there is no particular restriction on the bond form of the conjugated diene compound as long as it does not impair the object and effect of the present invention.
• the structural unit constituting the polymer block (B) is a structural unit derived from ⁇ -farnesene, a structural unit derived from ⁇ -farnesene and butadiene, or a structural unit derived from ⁇ -farnesene and isoprene
• the respective bond forms of ⁇ -farnesene, butadiene, and isoprene can be 1,2-bond, 1,13-bond, and 3,13-bond in the case of ⁇ -farnesene, 1,2-bond and 1,4-bond in the case of butadiene, and 1,2-bond, 3,4-bond, and 1,4-bond in the case of isoprene.
• the 1,2-bond and 3,13-bond of ⁇ -farnesene, the 1,2-bond of butadiene, and the 1,2-bond and 3,4-bond of isoprene are regarded as vinyl bond units, and the content of the vinyl bond units is regarded as the vinyl bond amount.
• the carbon positions of ⁇ -farnesene are numbered in the following order:
• the vinyl bond amount of the polymer block (B-1) is preferably 20 mol % or less, more preferably 15 mol % or less, and even more preferably 10 mol % or less, from the viewpoint of lowering the glass transition temperature (Tg) of the polymer block (B-1) and from the viewpoint of ease of production.
• the lower limit of the vinyl bond amount in the polymer block (B-1) may be 3 mol % or more, 4 mol % or more, or 5 mol % or more, from the viewpoint of ease of production.
• the vinyl bond amount in the polymer block (B-1) is preferably 3 to 20 mol %.
• the vinyl bond amount is a value calculated by 1 H-NMR measurement according to the method described in the Examples.
• the vinyl bond amount of at least one of the polymer blocks (B-1) is within the above range, and the vinyl bond amounts of all the polymer blocks (B-1) may be within the above range.
• the vinyl bond amount can be adjusted to the above range, for example, by adjusting the type and amount of a Lewis base used as a cocatalyst (vinylating agent) during polymerization.
• the amount of vinyl bonds in polymer block (B-2) is preferably 20 to 45 mol%, more preferably 25 to 44 mol%, and even more preferably 30 to 43 mol%, from the viewpoints of ease of production and low Tg.
• the total amount of vinyl bonds in polymer block (B) is preferably 3 to 45 mol%, more preferably 4 to 44 mol%, and even more preferably 5 to 43 mol%.
• the block copolymer (X) may contain, in addition to the polymer block (A), the polymer block (B-1) and the polymer block (B-2), a polymer block constituted by another monomer, so long as the effect of the present invention is not impaired.
• Examples of such other monomers include unsaturated hydrocarbon compounds such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, and 1-eicosene; and functional group-containing unsaturated compounds such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, methacrylonitrile, maleic acid, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethanesulfonic acid, 2-methacryloylethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacryl
• the block copolymer (X) does not contain a diblock material consisting of polymer block (A) and polymer block (B), or the content of the diblock material in the block copolymer (X) is more than 0% by mass and less than 60% by mass.
• the content of the diblock material in the block copolymer (X) is more preferably more than 0% by mass and not more than 50% by mass, even more preferably more than 0% by mass and not more than 40% by mass, still more preferably more than 0% by mass and not more than 30% by mass, still more preferably more than 0% by mass and not more than 20% by mass, and still more preferably more than 0% by mass and not more than 10% by mass.
• the total content of multiblock units containing a total of three or more polymer blocks (A) and polymer blocks (B) in the block copolymer (X) is preferably more than 40 mass % and 100 mass % or less.
• components such as unreacted polymer block (A) and unreacted polymer block (B) are usually about less than 1% by mass of the produced block copolymer (X) and can be ignored. Therefore, when such unreacted components are contained, the above mass ratio may be set with respect to the remainder excluding these.
• the pressure-sensitive adhesive composition is preferably crosslinked with at least one selected from the group consisting of the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%. At least one selected from the group consisting of the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) is crosslinked, thereby improving heat resistance, while the presence of the tackifier (Y) ensures a predetermined adhesiveness.
• a method for crosslinking at least one selected from the group consisting of the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) a method in which a photoradical polymerization initiator and a crosslinking agent described below are contained in a pressure-sensitive adhesive composition and irradiated with ultraviolet light can be mentioned.
• Components other than the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) may be crosslinked.
• at least one selected from the group consisting of the tackifier (Y) and the liquid rubber component (Z) described later may be further crosslinked.
• Block copolymer (X) is, for example, an unhydrogenated block copolymer (X0) containing polymer block (A) and polymer block (B-1), or when the block copolymer (X) is an unhydrogenated block copolymer (X0) containing polymer block (A), polymer block (B-1) and polymer block (B-2), it can be suitably produced by a polymerization step such as anionic polymerization.
• block copolymer (X) is a hydrogenated block copolymer (X1)
• it can be suitably produced by a step of hydrogenating a carbon-carbon double bond in a structural unit derived from a conjugated diene compound in the unhydrogenated block copolymer (X0).
• the unhydrogenated block copolymer (X0) can be produced by a solution polymerization method or the method described in JP-A 2012-502135 and JP-A 2012-502136. Of these, the solution polymerization method is preferred, and known methods such as ionic polymerization methods such as anionic polymerization and cationic polymerization, and radical polymerization methods can be applied. Of these, the anionic polymerization method is preferred.
• an aromatic vinyl compound, ⁇ -farnesene, and optionally a conjugated diene compound other than ⁇ -farnesene are successively added in the presence of a solvent, an anionic polymerization initiator, and optionally a Lewis base to obtain the unhydrogenated block copolymer (X0).
• anionic polymerization initiator examples include alkali metals such as lithium, sodium, and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium, and barium; lanthanoid rare earth metals such as lanthanum and neodymium; and compounds containing the above-mentioned alkali metals, alkaline earth metals, and lanthanoid rare earth metals.
• alkali metals such as lithium, sodium, and potassium
• alkaline earth metals such as beryllium, magnesium, calcium, strontium, and barium
• lanthanoid rare earth metals such as lanthanum and neodymium
• compounds containing alkali metals and alkaline earth metals are preferred, and organic alkali metal compounds are more preferred.
• organic alkali metal compound examples include organic lithium compounds such as methyl lithium, ethyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, hexyl lithium, phenyl lithium, stilbene lithium, dilithiomethane, dilithionaphthalene, 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, and 1,3,5-trilithiobenzene; sodium naphthalene, potassium naphthalene, and the like.
• organic lithium compounds are preferred, with n-butyl lithium and sec-butyl lithium being more preferred, and sec-butyl lithium being even more preferred.
• the organic alkali metal compound may be reacted with a secondary amine such as diisopropylamine, dibutylamine, dihexylamine, or dibenzylamine to form an organic alkali metal amide.
• a secondary amine such as diisopropylamine, dibutylamine, dihexylamine, or dibenzylamine.
• the amount of the organic alkali metal compound used in the polymerization varies depending on the molecular weight of the unhydrogenated block copolymer (X0), but is usually in the range of 0.01 to 3 mass % based on the total amount of the aromatic vinyl compound, ⁇ -farnesene, and the conjugated diene compound other than ⁇ -farnesene.
• solvent there are no particular limitations on the solvent as long as it does not adversely affect the anionic polymerization reaction.
• saturated aliphatic hydrocarbons such as n-pentane, isopentane, n-hexane, n-heptane, and isooctane
• saturated alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane
• aromatic hydrocarbons such as benzene, toluene, and xylene.
• Lewis bases play a role in controlling the microstructure of structural units derived from ⁇ -farnesene and structural units derived from conjugated diene compounds other than ⁇ -farnesene.
• Lewis bases include ether compounds such as dibutyl ether, diethyl ether, tetrahydrofuran, dioxane, and ethylene glycol diethyl ether; pyridine; tertiary amines such as N,N,N',N'-tetramethylethylenediamine and trimethylamine; alkali metal alkoxides such as potassium t-butoxide; and phosphine compounds.
• the amount is usually preferably in the range of 0.01 to 1,000 molar equivalents per mole of the anionic polymerization initiator.
• the temperature of the polymerization reaction is usually in the range of about -80 to +150°C, preferably 0 to 100°C, and more preferably 10 to 90°C.
• the polymerization reaction may be carried out batchwise or continuously.
• the unhydrogenated block copolymer (X0) can be produced by continuously or intermittently supplying each monomer to the polymerization reaction liquid so that the amounts of the aromatic vinyl compound, ⁇ -farnesene, and the conjugated diene compound other than ⁇ -farnesene present in the polymerization reaction system are within specific ranges, or by sequentially polymerizing each monomer in the polymerization reaction liquid so that a specific ratio is achieved.
• the polymerization reaction can be terminated by adding an alcohol such as methanol or isopropanol as a polymerization terminator.
• the obtained polymerization reaction liquid is poured into a poor solvent such as methanol to precipitate the unhydrogenated block copolymer (X0), or the polymerization reaction liquid is washed with water, separated, and then dried to isolate the unhydrogenated block copolymer (X0).
• Methods for isolating the unhydrogenated block copolymer (X0) include a method of solidifying the resin component (steam stripping) and a spray-drying method in which a polymer solution is heated to a high temperature and high pressure and sprayed under normal pressure to extract the resin component.
• the method for producing the block copolymer (X) may include the following: [i] a method of polymerizing a polymer block (A), a polymer block (B-1), and a polymer block (A) in this order, and [ii] A method in which the polymer block (A) and the polymer block (B-1) are polymerized in this order, and the ends of the polymer block (B-1) are coupled to each other using a coupling agent.
• the above method [i] is preferred from the viewpoint of efficient production.
• the block copolymer (X) further contains the polymer block (B-2), it can be produced by a method similar to the above method.
• the above coupling agents include, for example, divinylbenzene; polyfunctional epoxy compounds such as epoxidized 1,2-polybutadiene, epoxidized soybean oil, and tetraglycidyl-1,3-bisaminomethylcyclohexane; halides such as tin tetrachloride, tetrachlorosilane, trichlorosilane, trichloromethylsilane, dichlorodimethylsilane, and dibromodimethylsilane; ester compounds such as methyl benzoate, ethyl benzoate, phenyl benzoate, diethyl oxalate, diethyl malonate, diethyl adipate, dimethyl phthalate, and dimethyl terephthalate; carbonate compounds such as dimethyl carbonate, diethyl carbonate, and diphenyl carbonate; alkoxysilane compounds such as diethoxydimethylsilane, trimethoxy
• an unmodified block copolymer may be obtained as described above, but a modified block copolymer may also be obtained as described below.
• the unhydrogenated block copolymer (X0) may be modified before the hydrogenation step described below.
• the functional group that can be introduced include an amino group, an alkoxysilyl group, a hydroxyl group, an epoxy group, a carboxyl group, a carbonyl group, a mercapto group, an isocyanate group, and an acid anhydride group.
• Examples of the method for modifying the unhydrogenated block copolymer (X0) include a method of adding a coupling agent capable of reacting with the polymerization active terminal, such as tin tetrachloride, tetrachlorosilane, dichlorodimethylsilane, dimethyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, 3-aminopropyltriethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane, or 2,4-tolylenediisocyanate, a polymerization terminal modifier, such as 4,4'-bis(diethylamino)benzophenone or N-vinylpyrrolidone, or other modifiers described in JP-A-2011-132298, before adding a polymerization terminator.
• a coupling agent capable of reacting with the polymerization active terminal such as tin tet
• the copolymer after isolation can also be used by grafting with maleic anhydride or the like.
• the position where the functional group is introduced may be the polymerization terminal or the side chain of the unhydrogenated block copolymer (X0).
• the functional group may be one type or a combination of two or more types.
• the modifier is preferably used in an amount of 0.01 to 10 molar equivalents per mole of the anionic polymerization initiator.
• the block copolymer (X) may be converted to a hydrogenated block copolymer (X1) by subjecting the unhydrogenated block copolymer (X0) or modified block copolymer obtained by the above-mentioned method to a step of hydrogenation.
• the hydrogenation can be carried out by a known method.
• the hydrogenation reaction is carried out in a solution obtained by dissolving the unhydrogenated block copolymer (X0) in a solvent that does not affect the hydrogenation reaction, in which a Ziegler catalyst; a nickel, platinum, palladium, ruthenium or rhodium metal catalyst supported on carbon, silica, diatomaceous earth or the like; an organometallic complex having cobalt, nickel, palladium, rhodium or ruthenium metal or the like is present as a hydrogenation catalyst.
• a hydrogenation reaction may be carried out by adding a hydrogenation catalyst to the polymerization reaction liquid containing the unhydrogenated block copolymer (X0) obtained by the above-mentioned production method.
• the hydrogenation catalyst is preferably palladium carbon in which palladium is supported on carbon.
• the hydrogen pressure is preferably 0.1 to 20 MPa
• the reaction temperature is preferably 100 to 200° C.
• the reaction time is preferably 1 to 20 hours.
• the hydrogenated block copolymer (X1) can be isolated by pouring the hydrogenation reaction liquid obtained in the above step into a poor solvent such as methanol to precipitate the hydrogenated block copolymer (X1), or by washing the hydrogenation reaction liquid with water, separating it, and then drying it.
• a method for isolating the hydrogenated block copolymer (X1) a method of coagulating the resin component (steam stripping) or a spray drying method in which a polymer solution is heated to a high temperature and high pressure and sprayed under normal pressure to extract the resin component can also be used.
• the block copolymer (X) is substantially composed of only the unhydrogenated block copolymer (X0), substantially composed of only the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%, or substantially composed of both the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%.
• the hydrogenation rate of the block copolymer (X) is preferably 0 mol% or more and less than 50 mol%.
• the hydrogenation rate of the block copolymer (X) is preferably 0 to 49 mol%, more preferably 0 to 48 mol%, and even more preferably 0 to 47 mol%.
• the hydrogenation rate can be adjusted to the above range by controlling, for example, the amount of hydrogenation catalyst added and the reaction time.
• Examples of the carbon-carbon double bond in the conjugated diene compound unit present in the unhydrogenated block copolymer (X0) include the carbon-carbon double bond in the conjugated diene compound unit in the polymer block (B-1).
• examples of the carbon-carbon double bond in the conjugated diene compound unit in the polymer block (B-1) and the polymer block (B-2) include the carbon-carbon double bond in the conjugated diene compound unit in the polymer block (B-1) and the polymer block (B-2).
• the polymer block (B-1) and the polymer block (B-2) in the hydrogenated block copolymer (X1) have been hydrogenated, they are referred to as "polymer block (B-1)” and “polymer block (B-2)” in the same manner as before hydrogenation.
• the hydrogenation rate can be calculated from the values obtained by measuring 1 H-NMR of the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1), and more specifically, the hydrogenation rate can be calculated by the method described in the Examples.
• the weight average molecular weight (Mw) of the unhydrogenated block copolymer (X0) is preferably from 4,000 to 1,500,000, more preferably from 9,000 to 1,000,000, even more preferably from 30,000 to 800,000, and even more preferably from 50,000 to 500,000, from the viewpoints of coatability and heat resistance.
• the molecular weight distribution (Mw/Mn) of the unhydrogenated block copolymer (X0) is preferably from 1 to 6, more preferably from 1 to 4, even more preferably from 1 to 3, and even more preferably from 1 to 2. When the molecular weight distribution is within the above range, the viscosity of the unhydrogenated block copolymer (X0) varies little, making it easy to handle.
• the weight average molecular weight (Mw) of the hydrogenated block copolymer (X1) is preferably from 4,000 to 1,500,000, more preferably from 9,000 to 1,000,000, even more preferably from 30,000 to 800,000, and even more preferably from 50,000 to 500,000, from the viewpoints of coatability and heat resistance.
• the molecular weight distribution (Mw/Mn) of the hydrogenated block copolymer (X1) is preferably from 1 to 6, more preferably from 1 to 4, even more preferably from 1 to 3, and even more preferably from 1 to 2. When the molecular weight distribution is within the above range, the hydrogenated block copolymer (X1) has small variation in viscosity and is easy to handle.
• the molecular weight distribution (Mw/Mn) means a value measured by the method described in the examples below.
• the weight average molecular weight (Mw) of the block copolymer (X) is preferably 30,000 to 450,000, more preferably 35,000 to 400,000, even more preferably 40,000 to 350,000, particularly preferably 45,000 to 300,000, and most preferably 50,000 to 250,000.
• the weight average molecular weight of the block copolymer (X) can be adjusted to fall within the above range, for example, by adjusting the amount of monomer relative to the polymerization initiator.
• the tackifier (Y) can be selected from a wide variety of types depending on the application and required performance of the resulting pressure-sensitive adhesive composition.
• the tackifier (Y) is not particularly limited, and examples thereof include rosin-based compounds such as natural rosin, polymerized rosin, modified rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, pentaerythritol ester of modified rosin, hydrogenated rosin, and pentaerythritol ester of hydrogenated rosin; copolymers of natural terpene, three-dimensional polymers of natural terpene, aromatic modified terpene resins, hydrogenated products of aromatic modified terpene resins and derivatives thereof, terpene phenol resins, hydrogenated products of terpene phenol resins and derivatives thereof, terpene resins (mono
• suitable petroleum hydrocarbon compounds include terpene compounds and derivatives thereof; pinene resins; aliphatic petroleum hydrocarbon resins (C5 resins), hydrogenated aliphatic petroleum hydrocarbon resins and derivatives thereof, aromatic petroleum hydrocarbon resins (C9 resins), hydrogenated aromatic petroleum hydrocarbon resins, derivatives of hydrogenated aromatic petroleum hydrocarbon resins, hydrogenated aromatic modified alicyclic hydrocarbon resins (DCPD-C9 resins) and/or derivatives thereof, dicyclopentadiene resins, hydrogenated dicyclopentadiene resins and derivatives thereof, C5/C9 copolymer resins, hydrogenated C5/C9 copolymer resins and derivatives thereof, alicyclic petroleum hydrocarbon resins, hydrogenated alicyclic petroleum hydrocarbon resins and derivatives thereof; aromatic group-containing resins.
• the C5/C9 copolymer system is a copolymerized petroleum resin polymerized using a mixture of C5 fraction and C9 fraction as a raw material.
• tackifiers other than the various hydrogenated products and their derivatives mentioned above include Ester Gum AA-L, Ester Gum A, Ester Gum AAV, Ester Gum, Ester Gum 105, Ester Gum AT, Bencel A, Bencel AZ, Bencel C, Bencel D125, Bencel D160, Super Ester, Tamanor, Pine Crystal, and Arada, all manufactured by Arakawa Chemical Co., Ltd.
• Wingtack 86 Norsolnene manufactured by Cray Valley, Piccotac 8095, Piccotac 10 manufactured by Eastman Chemical Company 95, Piccotac 1098, Piccotac 1100, Escorez 1102, Escorez 1202, Escorez 1204LS, Escorez 1304, Escorez 1310, Escorez 1315, Escorez 224, Escorez 2101, Escorez 213, Escorez 807 manufactured by ExxonMobil Chemical Company, Sylvagum and and Sylvalite, Piccolyte manufactured by Ashland, YS Resin PX, YS Resin PXN, YS Polystar U, YS Polystar T, YS Polystar S, YS Polystar G, YS Polystar N, YS Polystar K, YS Polystar TH,
• the aliphatic tackifiers such as the above-mentioned aliphatic petroleum hydrocarbon resins (C5 resins), hydrogenated aliphatic petroleum hydrocarbon resins (C5 resins) and derivatives thereof, C5/C9 copolymer resins, and hydrogenated C5/C9 copolymer resins and derivatives thereof, are tackifiers in which the content of aliphatic hydrocarbon groups is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 88% by mass or more, and still more preferably 95% by mass or more.
• the aliphatic tackifier can be produced by homopolymerizing or copolymerizing a monomer having an aliphatic group and a polymerizable unsaturated group.
• Monomers having an aliphatic group and a polymerizable unsaturated group include, but are not limited to, natural and synthetic terpenes, for example, containing C5 or C6 cyclopentyl or cyclohexyl groups.
• Other monomers that can be used in the copolymerization include, but are not limited to, 1,3-butadiene, cis-1,3-pentadiene, trans-1,3-pentadiene, 2-methyl-1,3-butadiene, 2-methyl-2-butene, cyclopentadiene, dicyclopentadiene, terpene, and terpene-phenol resins.
• the aromatic tackifiers such as the aromatic petroleum hydrocarbon resins (C9 resins) and C5/C9 copolymer resins have an aromatic hydrocarbon group content of preferably 50 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, still more preferably 88 mass% or more, and still more preferably 95 mass% or more.
• the aromatic tackifier can be produced by homopolymerizing or copolymerizing a monomer having an aromatic group and a polymerizable unsaturated group.
• Examples of monomers each having an aromatic group and a polymerizable unsaturated group include, but are not limited to, styrene, ⁇ -methylstyrene, vinyltoluene, methoxystyrene, tert-butylstyrene, chlorostyrene, and indene monomers (including methylindene).
• monomers that can be used in the copolymerization are not particularly limited, but examples thereof include 1,3-butadiene, cis-1,3-pentadiene, trans-1,3-pentadiene, 2-methyl-1,3-butadiene, 2-methyl-2-butene, cyclopentadiene, dicyclopentadiene, terpene, and terpene-phenol resins.
• aromatic tackifiers include Endex 155, Crystallex 1120, Crystallex 3085, Crystallex 3100, Crystallex 5140, Crystallex F100, Plastrin 240, Plastrin 290, and Picotex 100 manufactured by Eastman Chemical Company, and Nitto Resin Coumarone G-90, V-120, and V-120S manufactured by Nippon Paint Chemical Industry Co., Ltd.
• tackifiers that have affinity for the blocks of the glass phase of block copolymers, such as resins having aromatic rings between molecules.
• resins include, but are not limited to, aromatic group-containing resins such as homopolymers or copolymers containing vinyltoluene, styrene, ⁇ -methylstyrene, coumarone, or indene as structural units.
• aromatic group-containing resins such as homopolymers or copolymers containing vinyltoluene, styrene, ⁇ -methylstyrene, coumarone, or indene as structural units.
• KristAlEx and PlAstolyN (trade names, manufactured by Eastman Chemical Co.) containing ⁇ -methylstyrene are preferred.
• These tackifiers may be used alone or in combination of two or more.
• the content of the tackifier (Y) is preferably 50 to 170 parts by mass, more preferably 60 to 150 parts by mass, and even more preferably 70 to 120 parts by mass, relative to 100 parts by mass of the block copolymer (X).
• the pressure-sensitive adhesive composition may contain a plasticizer (Z).
• a plasticizer Z
• the coating property and pressure-sensitive adhesive property become good.
• the plasticizer (Z) include a liquid rubber component (Za), a biomass-derived plasticizer (Zb), a synthetic plasticizer (Zc), a vegetable oil (Zd), etc. These are preferably plasticizers that do not have a carboxy group. These may be contained alone or in combination of two or more kinds.
• the pressure-sensitive adhesive composition further comprises at least one selected from the group consisting of a liquid rubber component (Za), a biomass-derived plasticizer (Zb), and a synthetic plasticizer (Zc).
• the liquid rubber component (Za) contained in the adhesive composition is a synthetic rubber having a melt viscosity at 38° C. (hereinafter also referred to as "38° C. melt viscosity") of 2,000 Pa ⁇ s or less.
• the melt viscosity at 38° C. of the liquid rubber component (Za) can be measured by using a Brookfield viscometer (manufactured by BROOKFIELD ENGINEERING LABS. INC.).
• the liquid rubber component (Za) may be a liquid rubber that has not been hydrogenated, or may be a hydrogenated liquid rubber.
• the "liquid rubber component (Za)” includes a liquid rubber before hydrogenation (hereinafter, sometimes referred to as an unhydrogenated liquid rubber (Za0)) and a liquid rubber obtained by hydrogenating the unhydrogenated liquid rubber (Za0) (hereinafter, sometimes referred to as a hydrogenated liquid rubber (Za1)).
• the liquid rubber component (Za) may contain both the unhydrogenated liquid rubber (Za0) and the hydrogenated liquid rubber (Za1).
• the liquid rubber component (Za) will be described below, but unless otherwise specified, this description applies to both the unhydrogenated liquid rubber (Za0) and the hydrogenated liquid rubber (Za1).
• liquid rubber component (Za) examples include liquid diene rubbers such as liquid polyfarnesene rubber, liquid isoprene rubber, liquid butadiene rubber, liquid styrene butadiene rubber, etc.
• liquid diene rubbers such as liquid polyfarnesene rubber, liquid isoprene rubber, liquid butadiene rubber, liquid styrene butadiene rubber, etc.
• liquid polyfarnesene rubber and liquid butadiene rubber are preferred, and liquid polyfarnesene rubber is more preferred.
• the liquid diene rubber may contain other monomer units such as conjugated diene compound units other than ⁇ -farnesene, isoprene and butadiene, and aromatic vinyl compound units.
• the liquid diene rubber is a polymer containing at least one of ⁇ -farnesene, isoprene and butadiene units in an amount of 50% by mass or more based on all monomer units constituting the polymer.
• the total content of the ⁇ -farnesene units, isoprene units and butadiene units is preferably 60% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, based on all monomer units constituting the liquid diene rubber.
• the liquid rubber component (Za) can be prepared by a known method, for example, by polymerizing at least one selected from the group consisting of ⁇ -farnesene, isoprene, and butadiene, and a monomer added as necessary, by a method such as emulsion polymerization or solution polymerization. Among these, the solution polymerization method is particularly preferred.
• the polymerized monomers i.e., the unhydrogenated liquid rubber (Za0)
• the polymerized monomers can be hydrogenated in the same manner as in the above-mentioned method for producing the hydrogenated block copolymer (X1) to obtain the hydrogenated liquid rubber (Za1).
• the above-mentioned adhesive composition further contains a liquid rubber component (Za) from the viewpoints of compatibility with the block copolymer (X), adhesive properties, and heat resistance, and the liquid rubber component (Za) preferably contains at least one selected from the group consisting of unhydrogenated liquid rubber (Za0), which is a liquid rubber that has not been hydrogenated, and hydrogenated liquid rubber (Za1), which is a liquid rubber that has been hydrogenated and has a hydrogenation rate of 90 mol% or less.
• unhydrogenated liquid rubber Za0
• hydrogenated liquid rubber (Za1) which is a liquid rubber that has been hydrogenated and has a hydrogenation rate of 90 mol% or less.
• the liquid rubber component (Za) consists essentially of only the unhydrogenated liquid rubber (Za0), or consists essentially of only the hydrogenated liquid rubber (Za1) having a hydrogenation rate of 90 mol % or less, or consists essentially of both the unhydrogenated liquid rubber (Za0) and the hydrogenated liquid rubber (Za1) having a hydrogenation rate of 90 mol % or less, and it is more preferable that the liquid rubber component (Za) consists essentially of only the unhydrogenated liquid rubber (Za0).
• liquid rubber in addition to an embodiment consisting of only the above-mentioned unhydrogenated liquid rubber (Za0) and an embodiment consisting of only the above-mentioned hydrogenated liquid rubber (Za1), the liquid rubber may also contain components such as hydrogenated liquid rubber having a hydrogenation rate of more than 90 mol%, which are inevitably present in the process of producing the liquid rubber component.
• the content of the liquid rubber component (Za) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, even more preferably 31 parts by mass or more, even more preferably 40 parts by mass or more, even more preferably 46 parts by mass or more, even more preferably 50 parts by mass or more, particularly preferably 51 parts by mass or more, and from the viewpoint of suppressing bleeding, is preferably 300 parts by mass or less, more preferably 270 parts by mass or less, even more preferably 250 parts by mass or less, and even more preferably 230 parts by mass or less.
• the content of the liquid rubber component (Za) is preferably 10 to 300 parts by mass with respect to 100 parts by mass of the block copolymer (X).
• the weight average molecular weight of the liquid rubber component (Za) is preferably 2,000 to 30,000, more preferably 2,500 to 25,000, even more preferably 3,000 to 20,000, still more preferably 3,500 to 17,000, and particularly preferably 4,000 to 15,000, from the viewpoints of dispersibility and heat resistance.
• the weight average molecular weight of the liquid rubber component (Za) can be adjusted to the above range, for example, by adjusting the amount of the conjugated diene compound relative to the polymerization initiator used in the polymerization.
• the melt viscosity at 38°C of the liquid rubber component (Za) is preferably 0.1 to 1,000 Pa ⁇ s, more preferably 0.2 to 500 Pa ⁇ s, even more preferably 0.3 to 300 Pa ⁇ s, and still more preferably 0.3 to 100 Pa ⁇ s, from the viewpoint of ensuring dispersibility and adhesiveness in the block copolymer (X).
• the melt viscosity at 38°C of the liquid rubber component (Za) can be adjusted to the above range, for example, by adjusting the type of conjugated diene compound used or the hydrogenation rate of the polymer thereof, or by adjusting the weight average molecular weight of the liquid rubber component (Za) used.
• the weight average molecular weight (Mw) of the unhydrogenated liquid rubber (Za0) is preferably from 3,000 to 200,000, more preferably from 4,000 to 100,000, even more preferably from 5,000 to 50,000, and even more preferably from 8,000 to 15,000, from the viewpoint of adhesiveness.
• the molecular weight distribution (Mw/Mn) of the unhydrogenated liquid rubber (Za0) is preferably from 1 to 5, more preferably from 1 to 4, even more preferably from 1 to 3, and even more preferably from 1 to 2. When the molecular weight distribution is within the above range, the viscosity of the unhydrogenated liquid rubber (Za0) varies little, making it easy to handle.
• the weight average molecular weight (Mw) of the hydrogenated liquid rubber (Za1) is preferably from 3,000 to 300,000, more preferably from 5,000 to 250,000, even more preferably from 10,000 to 200,000, and even more preferably from 15,000 to 150,000, from the viewpoint of adhesiveness.
• the molecular weight distribution (Mw/Mn) of the hydrogenated liquid rubber (Za1) is preferably from 1 to 5, more preferably from 1 to 4, even more preferably from 1 to 3, and even more preferably from 1 to 2. When the molecular weight distribution is within the above range, the hydrogenated liquid rubber (Za1) has a small variation in viscosity and is easy to handle.
• the pressure-sensitive adhesive composition may contain a biomass-derived plasticizer (Zb).
• the biomass-derived plasticizer (Zb) is preferably a biomass-derived plasticizer having no carboxy group.
• Specific examples of the biomass-derived plasticizer (Zb) include compounds represented by the following general formula (1) and compounds represented by the following general formula (2). These may be used alone or in combination of two or more.
• n 1 to n 3 each independently represent 1 or 3
• R 1 to R 6 each independently represent a hydrogen atom or an unsubstituted hydrocarbon group
• R 1 and R 2 have a total of 14 carbon atoms
• R 3 and R 4 have a total of 14 carbon atoms
• R 5 and R 6 have a total of 14 carbon atoms
• R 1 to R 6 may have a branched structure.
• n4 and n5 each independently represent 1 or 3
• R 7 to R 10 each independently represent a hydrogen atom or an unsubstituted hydrocarbon group
• the total number of carbon atoms of R 7 and R 8 is 14
• the total number of carbon atoms of R 9 and R 10 is 14, and
• R 7 to R 10 may have a branched structure.
• Specific examples of compounds represented by general formula (1) include compounds represented by the following structural formulas (1-1) to (1-8).
• Specific examples of compounds represented by general formula (2) include compounds represented by the following structural formulas (2-1) to (2-8).
• a biomass-derived plasticizer (Zb) product is VIVA-B-FIX10227, manufactured by H&R (a mixture having a structure represented by the above general formula (1), biobased content (ASTM D6866-21): 100% by mass).
• the content of the biomass-derived plasticizer (Zb) in the pressure-sensitive adhesive composition is, from the viewpoint of easily ensuring appropriate pressure-sensitive adhesive properties and coatability, preferably 3 mass% or more, more preferably 5 mass% or more, even more preferably 8 mass% or more, and is preferably 40 mass% or less, more preferably 35 mass% or less, even more preferably 30 mass% or less.
• the content of the biomass-derived plasticizer (Zb) in the pressure-sensitive adhesive composition is preferably 3 to 40 mass%.
• the content of the biomass-derived plasticizer (Zb) is preferably 40 parts by mass or more, more preferably 60 parts by mass or more, even more preferably 80 parts by mass or more, even more preferably 90 parts by mass or more, particularly preferably 95 parts by mass or more, and most preferably 100 parts by mass.
• biobased content of the biomass-derived plasticizer (Zb) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and most preferably 100% by mass.
• the kinetic viscosity of the biomass-derived plasticizer (Zb) at 40°C is not particularly limited, but is preferably 100 cSt or less, more preferably 80 cSt or less, and even more preferably 60 cSt or less.
• the melting point of the biomass-derived plasticizer (Zb) is not particularly limited, but is preferably -70°C or higher, more preferably -60°C or higher, even more preferably -50°C or higher, and is preferably 20°C or lower, more preferably 10°C or lower, even more preferably 0°C or lower.
• Synthetic Plasticizer (Zc) examples include oil-based softeners such as paraffinic, naphthenic, and aromatic process oils, mineral oils, and white oils; phthalic acid derivatives such as dioctyl phthalate and dibutyl phthalate; liquid cooligomers of ethylene and ⁇ -olefins; liquid paraffin; polybutene; low molecular weight polyisobutylene; liquid polydienes such as liquid polybutadiene, liquid polyisoprene, liquid polyisoprene/butadiene copolymers, liquid styrene/butadiene copolymers, and liquid styrene/isoprene copolymers; and hydrogenated or modified products thereof. These may be used alone or in combination of two or more.
• paraffinic and naphthenic process oils from the viewpoint of compatibility with the block copolymer (X), paraffinic and naphthenic process oils; liquid cooligomers of ethylene and ⁇ -olefins; liquid paraffin; and low molecular weight polyisobutylene are preferred, with paraffinic and naphthenic process oils being more preferred.
• the content of the synthetic plasticizer (Zc) in the adhesive composition is preferably 3 mass% or more, more preferably 5 mass% or more, even more preferably 8 mass% or more, from the viewpoint of ensuring appropriate adhesiveness and coatability, and is preferably 40 mass% or less, more preferably 35 mass% or less, even more preferably 30 mass% or less. In other words, the content of the synthetic plasticizer (Zc) in the adhesive composition is preferably 3 to 40 mass%.
• ⁇ vegetable oil (Zd) examples include castor oil, cottonseed oil, linseed oil, safflower oil, rapeseed oil, soybean oil, safflower oil, Japan wax, pine oil, corn oil, peanut oil, olive oil, palm oil, palm olein, palm stearin, and other plant-derived oils and fats, as well as interesterified oils, hydrogenated oils, and fractionated oils thereof. These may be used alone or in combination of two or more.
• the biobased content of the vegetable oil (Zd) is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more.
• the content of the vegetable oil (Zd) in the adhesive composition is preferably 3 mass% or more, more preferably 5 mass% or more, even more preferably 8 mass% or more, from the viewpoint of ensuring appropriate adhesiveness and coatability, and is preferably 40 mass% or less, more preferably 35 mass% or less, even more preferably 30 mass% or less. In other words, the content of the vegetable oil (Zd) in the adhesive composition is preferably 3 to 40 mass%.
• the pressure-sensitive adhesive composition may contain components other than the block copolymer (X), the tackifier (Y), and the plasticizer (Z). Examples of such components include antioxidants, crosslinking agents, photoradical polymerization initiators, thermal aging inhibitors, light stabilizers, antistatic agents, release agents, flame retardants, foaming agents, pigments, dyes, brighteners, etc.
• the pressure-sensitive adhesive composition may also contain a solvent as described below in the section "Method for producing pressure-sensitive adhesive composition.” Representative other components will be described below.
• antioxidant examples include hindered phenol-based antioxidants, phosphorus-based antioxidants, hydroxylamine-based antioxidants, hindered phenol/phosphorus mixed antioxidants, and oxygen absorbers.
• Hindered phenol antioxidants include IRGANOX1010 (manufactured by BASF), Adeka STAB AO-60 (manufactured by ADEKA Corporation), Sumilizer BP-101 (manufactured by Sumitomo Chemical Co., Ltd.) (pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]), IRGANOX1035 (manufactured by BASF) (2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]), IRGANOX1076 (manufactured by BASF) (octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), and IRGANOX1098 (manufactured by BASF) (N,N'-hexamethylenebis(3,5-di-
• IRGANOX1135 BASF
• IRGANOX1330 BASF
• IRGANOX1726 BASF
• IRGANOX1425 BASF
• IRGANOX1520 BASF
• IRGANOX245 BASF
• Phosphorus-based antioxidants include IRGAFOS12 (BASF, molecular weight 1462.9) (6,6',6''-[nitrilotris(ethyleneoxy)]tris(2,4,8,10-tetra-tert-butylbenzo[d,f][1,3,2]dioxaphosphepine)), IRGAFOS38 (BASF, molecular weight 514) (ethyl bis(2,4-di-tert-butyl-6-methylphenyl) phosphite), and IRGAFOS168 (BASF, molecular weight 646) ), Adeka STAB 2112 (manufactured by ADEKA CORPORATION), Sumilizer P-16 (manufactured by Sumitomo Chemical Co., Ltd.) (tris(2,4-di-t-butylphenyl)phosphite), Adeka STAB PEP-8 (manufactured by ADEKA CORPORATION) (diste
• Hydroxylamine antioxidants include IRGASTAB FS 042 (manufactured by BASF) (N,N-dioctadecylhydroxylamine).
• the oxygen absorbent is an iron powder oxygen absorbent.
• the iron powder oxygen absorbent is prepared by combining 0.1 to 50 parts by weight of a metal halide, for example, an alkali metal or alkaline earth metal halide such as sodium chloride, sodium bromide, calcium chloride, or magnesium chloride, such as chlorine, bromine, or iodine, with 100 parts by weight of iron powder having a surface area of 0.5 m 2 /g or more. This may be a mixture of the two, or the iron powder surface may be coated with the metal halide.
• the oxygen absorbent used in the present invention may further be combined with porous particles such as zeolite impregnated with water to further promote the oxidation of iron by the oxygen.
• the amount of the antioxidant is not particularly limited, but is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 7 parts by mass, and even more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the total of the block copolymer (X), tackifier resin (Y), and plasticizer (Z).
• the adhesive composition contains a crosslinking agent
• at least the block copolymer (X) is crosslinked with the crosslinking agent, thereby further improving the heat resistance of the adhesive composition.
• the adhesive composition contains a crosslinking agent and a photoradical polymerization initiator
• the adhesiveness of the adhesive composition can be reduced by irradiation with light such as UV light, and the adhesive composition can be preferably used for applications and adhesive products that require the property of being peelable from an adherend when the adherend is no longer required to be temporarily fixed, such as a dicing tape for temporary fixation of a semiconductor wafer.
• the crosslinking agent is preferably a polythiol derived from mercaptocarboxylic acid, more preferably a polythiol derived from 3-mercaptopropionic acid.
• the polythiol (B) preferably has a plurality of mercaptoacyloxy groups in the molecule, more preferably 2 to 6. Specific examples of the mercaptoacyloxy group include a 3-mercaptopropionyloxy group [HS-(CH 2 ) 2 -COO-] and a 3-mercaptobutyloxy group [HS-CH(CH 3 )-CH 2 -COO-], and the 3-mercaptopropionyloxy group is preferred.
• a thiyl radical is generated by the radical derived from the photoradical polymerization initiator, and the thiyl radical is added to the unsaturated bond of an allyl ether group and/or a vinyl ether, promoting a curing (crosslinking) reaction.
• polythiol (B) examples include tetraethylene glycol bis(3-mercaptopropionate) represented by the following chemical formula (I), trimethylolpropane tris(3-mercaptopropionate) represented by the following chemical formula (II), tris[(3-mercaptopropionyloxy)-ethyl]isocyanurate represented by the following chemical formula (III), pentaerythritol tetrakis(3-mercaptopropionate) represented by the following chemical formula (IV), dipentaerythritol hexakis(3-mercaptopropionate) represented by the following chemical formula (V), 1,4-bis(3-mercaptobutyryloxy)butane represented by the following chemical formula (VI), pentaerythritol tetrakis(3-mercaptobutyrate) represented by the following chemical formula (VII), and the following chemical formulas: 1,3,5-tris(3-mercaptobutyloxy
• the pressure-sensitive adhesive composition may contain a monomer having a radically polymerizable carbon-carbon double bond as a crosslinking agent.
• the monomer having a radically polymerizable carbon-carbon double bond means a monomer that can generate radicals and polymerize by applying active energy rays or heat in the presence of the above-mentioned photoradical polymerization initiator.
• Examples of monomers having a radically polymerizable carbon-carbon double bond include mono-substituted vinyl compounds such as styrene, acrylates, acrylamides, acrylonitrile, vinyl acetate, and vinyl chloride; 1,1-disubstituted vinyl compounds such as ⁇ -methylstyrene, methacrylates, and methacrylamides; cyclic olefins such as acenaphthylene and N-substituted maleimides; and conjugated diene compounds such as butadiene and isoprene.
• mono-substituted vinyl compounds such as styrene, acrylates, acrylamides, acrylonitrile, vinyl acetate, and vinyl chloride
• 1,1-disubstituted vinyl compounds such as ⁇ -methylstyrene, methacrylates, and methacrylamides
• cyclic olefins such as acenaphthylene and
• (meth)acrylates are preferred, and monofunctional (meth)acrylates, bifunctional (meth)acrylates, and trifunctional or higher polyfunctional (meth)acrylates can be used.
• acrylates which are monomers having a radically polymerizable carbon-carbon double bond, may be referred to as acrylic crosslinking agents.
• Examples of monofunctional (meth)acrylates include alkyl mono(meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate; cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and isobornyl (meth)acrylate.
• alkyl mono(meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, iso
• alicyclic mono(meth)acrylates such as dicyclopentenyl (meth)acrylate and dicyclopentenyloxyethyl (meth)acrylate
• dicyclopentenyl group-containing mono(meth)acrylates such as phenyl acrylate and benzyl acrylate
• phenoxy group-containing mono(meth)acrylates such as phenoxy hydroxypropyl (meth)acrylate, phenoxy ethyl (meth)acrylate, phenoxy ethylene glycol (meth)acrylate and phenoxy polyethylene glycol (meth)acrylate.
• (Meth)acrylates alkoxyalkyl mono(meth)acrylates such as 2-butoxyethyl (meth)acrylate; hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and butoxyhydroxypropyl (meth)acrylate; amino group-containing (meth)acrylates such as N,N-diethylaminoethyl (meth)acrylate and N,N-dimethylaminoethyl (meth)acrylate; epoxy groups such as glycidyl (meth)acrylate;
• suitable (meth)acrylates include alkoxy group-containing (meth)acrylates; alkoxy dialkylene glycol mono(meth)acrylates such as methoxy diethylene glycol (meth)acrylate and methoxy dipropylene glycol (meth)acrylate; fluorine group-containing (meth)acrylates such
• Bifunctional (meth)acrylates include, for example, alkylene glycol di(meth)acrylates such as 1,4-butanediol di(meth)acrylate, neopentyl glycol diacrylate, 1,6-hexanediol di(meth)acrylate (also known as "1,6-bis(acryloyloxy)hexane") and 1,9-nonanediol di(meth)acrylate; polyalkylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate and tripropylene glycol di(meth)acrylate; hydrochloric acid diacrylates such as ethylene glycol di(meth)acrylate, ...
• alkylene glycol di(meth)acrylates such as 1,4-butanediol di(meth)acrylate, neopentyl glycol diacrylate, 1,6-hexanediol di(
• Di(meth)acrylates having an ester group-containing diol skeleton such as aryloxypivalate esters and neopentyl glycol di(meth)acrylate; alicyclic di(meth)acrylates, such as dicyclopentanyl di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and ethoxylated hydrogenated bisphenol A di(meth)acrylate; hydroxypropyl di(meth)acrylate, diethylene glycol bis(hydroxypropyl(meth)acrylate), and propoxylated bisphenol A bis(hydroxyfluoropropyl(meth)acrylate).
• ester group-containing diol skeleton such as aryloxypivalate esters and neopentyl glycol di(meth)acrylate
• alicyclic di(meth)acrylates such as dicyclopentanyl di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and
• trifunctional or higher polyfunctional (meth)acrylates examples include trimethylolpropane-type polyfunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and hydroxypropylated trimethylolpropane tri(meth)acrylate; pentaerythritol-type polyfunctional (meth)acrylates such as pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and monohydroxypentaerythritol tri(meth)acrylate; and isocyanurate-type polyfunctional (meth)acrylates such as tris((meth)acryloxyethyl)isocyanurate.
• trimethylolpropane-type polyfunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate, ditrimethylolpropane t
• the amount of the crosslinking agent is not particularly limited, but is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 7 parts by mass, and even more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the total of the block copolymer (X), tackifier resin (Y), and plasticizer (Z).
• an intramolecular cleavage type photoradical polymerization initiator and/or a hydrogen abstraction type photoradical polymerization initiator can be used.
• the intramolecular cleavage type photoradical polymerization initiator include benzoin derivatives, benzyl ketals [e.g., Fujifilm Wako Pure Chemical Industries, Ltd., product name: Irgacure 651 (2,2-dimethoxy-1,2-diphenylethane-1-one)], ⁇ -hydroxyacetophenones [e.g., Fujifilm Wako Pure Chemical Industries, Ltd., product name: Darocur 1173 (2-hydroxy-2-methyl-1-phenylpropan-1-one), Irgacure 184 (1-hydroxycyclohexyl phenyl ketone), Irgacure 127 (2-hydroxy-1- ⁇ 4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]
• Hydrogen abstraction type photoradical polymerization initiators include a combination of benzophenones and amines, and a combination of thioxanthone and amines.
• an intramolecular cleavage type and a hydrogen abstraction type may be used in combination.
• oligomerized ⁇ -hydroxyacetophenone and acrylated benzophenones are preferred.
• examples include oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] [e.g., Lamberti S.p.A., product name: ESACUREKIP150, etc.], acrylated benzophenone [e.g., Daicel U.C.B., product name: Ebecryl P136, etc.], and imide acrylate.
• oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] e.g., Lamberti S.p.A., product name: ESACUREKIP150, etc.
• acrylated benzophenone e.g., Daicel U.C.B., product name: Ebecryl P136, etc.
• imide acrylate e.g., imide acrylate.
• the amount of the photoradical polymerization initiator contained in the adhesive composition is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 3 parts by mass, per 100 parts by mass of the total of the block copolymer (X), tackifier resin (Y), and plasticizer (Z) contained in the adhesive composition.
• a known photosensitizer can also be used together with the photoradical polymerization initiator.
• the bio-based degree of the pressure-sensitive adhesive composition is, from the viewpoint of reducing petroleum-derived raw materials and ease of production, preferably 10 to 100 mass%, more preferably 10 to 90 mass%, even more preferably 13 to 85 mass%, still more preferably 15 to 80 mass%, still more preferably 17 to 78 mass%, still more preferably 19 to 76 mass%, still more preferably 25 to 74 mass%, still more preferably 30 to 72 mass%, still more preferably 35 to 70 mass%, and particularly preferably 38 to 70 mass%.
• the bio-based content is measured in detail by the method described in the Examples.
• the haze which is an index correlating with compatibility, can be made low, and for example, it is possible to make it 35% or less, 10% or less, or 5% or less.
• the haze is measured in accordance with JIS K 7136:2000, and more specifically, is measured by the method described in the examples.
• the 180° peel strength of the pressure-sensitive adhesive composition is, from the viewpoint of ensuring high pressure-sensitive adhesive properties, preferably 10.0 N/25 mm or more, more preferably 15.0 N/25 mm or more, and even more preferably 20.0 N/25 mm or more.
• the tackiness is preferably 2.0 to 9.5 N/25 mm, more preferably 3.0 to 9.0 N/25 mm, even more preferably 3.5 to 8.5 N/25 mm, and still more preferably 4.0 to 8.0 N/25 mm.
• the 180° peel strength is measured by the method described in detail in the Examples.
• the adhesive composition has a shear interface fracture temperature (SAFT) calculated from the weight drop time under the conditions of an adhesive area of 25 mm ⁇ 25 mm, a weight of 500 g, a temperature range of 40 to 205° C., and a heating rate of 0.5° C./min in accordance with ASTM D3654M:2019, and is preferably 95° C. or higher, more preferably 100° C. or higher, and even more preferably 110° C. or higher, from the viewpoint of ensuring sufficient heat resistance.
• the shear interface fracture temperature is preferably 130° C. or higher, more preferably 150° C. or higher, even more preferably 180° C. or higher, still more preferably 200° C. or higher, still more preferably 205° C. or higher, and particularly preferably more than 205° C.
• the SAFT is measured by the method described in detail in the Examples.
• the melt viscosity of the adhesive composition measured at 180°C is preferably 16,000 mPa ⁇ s or less, more preferably 15,000 mPa ⁇ s or less, even more preferably 14,500 mPa ⁇ s or less, and even more preferably 14,000 Pa ⁇ s or less, from the viewpoint of processability and ease of application as a hot melt adhesive composition. Also, from the viewpoint of ease of handling as a hot melt adhesive composition, it is preferably 1,000 mPa ⁇ s or more, more preferably 1,500 mPa ⁇ s or more, even more preferably 1,800 mPa ⁇ s or more, and even more preferably 2,000 mPa ⁇ s or more.
• the melt viscosity of the adhesive composition measured at 180°C is preferably 1,000 to 16,000 mPa ⁇ s.
• the melt viscosity of the adhesive composition means a viscosity measured at 180° C. using a Brookfield viscometer (B-type viscometer).
• a method for producing a pressure-sensitive adhesive composition includes the steps of: (I) a step of dissolving the block copolymer (X) and the tackifier (Y) in a solvent and then distilling off the solvent, or (II) A step of melt-kneading the block copolymer (X) and the tackifier (Y).
• production method (I) includes a step of preparing a mixed liquid by mixing a solution (X') containing a block copolymer (X) and a first solvent, and a solution (Y') containing a tackifier (Y) and a second solvent (step 1-1); It is preferable that the method further comprises a step (step 1-2) of removing the first and second solvents contained in the mixed liquid to obtain a resin component.
• the first solvent and the second solvent include cyclopentane, cyclohexane, cycloheptane, cyclooctane, etc.
• the first solvent and the second solvent may be the same or different.
• the constraints on the viscosity of the tackifier (Y) that can be used are reduced. This allows for greater freedom in designing the adhesive composition. In addition, it becomes easier to use a tackifier (Y) with a high viscosity, which makes it easier to improve the physical properties, such as the adhesion retention, of the adhesive composition.
• the block copolymer (X) and the tackifier (Y) may be added simultaneously to a common solvent, or the block copolymer (X) may be added to a solvent and then the tackifier (Y) may be added to the solvent, or the tackifier (Y) may be added to a solvent and then the block copolymer (X) may be added to the solvent.
• the block copolymer (X) and the tackifier (Y) may be melt-kneaded in advance to prepare a mixture, which may then be dissolved in a solvent.
• the plasticizer (Z) it is preferable to dissolve the block copolymer (X), the tackifier (Y), and the plasticizer (Z) in a solvent.
• any two of the block copolymer (X), the tackifier (Y), and the plasticizer (Z) are mixed first, the mixture is dissolved in a solvent, and then the remaining component is dissolved in the obtained solution, or the mixture is dissolved in a first solvent, the remaining component is dissolved in the first solvent or a second solvent different from the first solvent, and the solutions are mixed.
• the block copolymer (X) and the plasticizer (Z) may be melt-kneaded in advance to prepare a mixture, to which the tackifier (Y) is added and then dissolved in a solvent.
• other additives may be added at an appropriate timing.
• step 1-2 above methods for extracting the polymer from the mixed liquid include solidifying the resin components (steam stripping) and spray drying, in which the polymer solution is heated to high temperature and pressure and sprayed under normal pressure to extract the resin components.
• production method (II) has a step (step 2-1) of melt-kneading the block copolymer (X) and the tackifier (Y).
• step 2-1 of melt-kneading the block copolymer (X) and the tackifier (Y).
• the production method (II) has the advantages that a solvent is not required and that many types of pressure-sensitive adhesive compositions can be easily produced in small lots using the same production equipment.
• melt-kneading step (step 2-1) in the method for producing a pressure-sensitive adhesive composition, it is preferable to melt the block copolymer (X) and then add the tackifier (Y) and perform melt-kneading, from the viewpoint of easily increasing the dispersibility of the tackifier (Y).
• the plasticizer (Z) may be mixed in advance with at least one selected from the group consisting of the block copolymer (X) and the tackifier (Y), and the other component or other additives may be added to this mixture.
• a mixture containing a plasticizer (Z) such as a liquid rubber component (Za) at a relatively high concentration relative to the block copolymer (X) is prepared, and a tackifier (Y) is added to this mixture and melt-kneaded, whereby a pressure-sensitive adhesive composition in which the plasticizer (Z) is diluted to a predetermined concentration can be prepared.
• a plasticizer (Z) such as a liquid rubber component (Za) at a relatively high concentration relative to the block copolymer (X)
• a tackifier (Y) is added to this mixture and melt-kneaded, whereby a pressure-sensitive adhesive composition in which the plasticizer (Z) is diluted to a predetermined concentration can be prepared.
• the pressure-sensitive adhesive composition according to this embodiment can be used in various methods as follows.
• Method of use i): The above adhesive composition is used as an adhesive as it is, and two adherends are adhesively bonded via a layer of the adhesive composition (adhesive layer).
• the adhesive composition may be applied to at least one of the two adherends, and then the two adherends may be pressed relative to each other via the adhesive layer, or the two adherends may be arranged with a small space therebetween, and the adhesive composition may be filled into the space.
• the adhesive layer may be directly applied to the adherend, or the adhesive layer may be applied to a temporary support and transferred onto the adherend.
• the two adherends may be placed with a small space between them, and the adhesive composition that has been heated and melted may be filled into the space.
• the adherends When at least one of the adherends has UV light transmissibility, it is also possible to perform crosslinking of the adhesive composition by irradiating UV light through the adherend having UV light transmissibility after bonding one adherend to the other through the adhesive layer, or after filling the space between the two adherends with the adhesive composition. In this method, it is preferable to irradiate with UV light within a range in which the adhesiveness of the adhesive layer does not decrease excessively.
• the adhesive layer is irradiated with UV light to promote crosslinking and reduce the adhesiveness of the adhesive layer, thereby making it possible to easily peel the adhesive layer from the adherend.
• an oxygen barrier film such as a polypropylene film, a polyethylene terephthalate film, a Teflon (registered trademark) film, etc. to prevent the surface from coming into contact with oxygen, and then irradiate with UV light through the oxygen barrier film, or irradiate with UV light in an atmosphere in which oxygen has been replaced with an inert gas such as nitrogen gas or carbon dioxide gas.
• ⁇ -Farnesene (purity 97.6% by mass, manufactured by Amyris, Inc.) was purified with 3 ⁇ molecular sieves and distilled under a nitrogen atmosphere to remove hydrocarbon impurities such as zingiberene, bisabolene, farnesene epoxide, farnesol isomers, E,E-farnesol, squalene, ergosterol, and several dimers of farnesene, and was then used in the following polymerization.
• the materials used in the following examples and comparative examples are as follows.
• Weight average molecular weight of polymer block (A) Weight average molecular weight of polymer block (B) Weight average molecular weight of unhydrogenated block polymer Molecular weight distribution of unhydrogenated block polymer Weight average molecular weight of hydrogenated block polymer Molecular weight distribution of hydrogenated block polymer Weight average molecular weight of unhydrogenated liquid rubber Molecular weight distribution of unhydrogenated liquid rubber
• the measuring apparatus and conditions are as follows.
• Hydrogenation rate (mol %) ⁇ 1-(ratio of the peak area derived from carbon-carbon double bonds to the peak area derived from styrene in the hydrogenated block copolymer)/(ratio of the peak area derived from carbon-carbon double bonds to the peak area derived from styrene in the unhydrogenated block copolymer) ⁇ 100
• the amount of vinyl bonds was calculated in the same manner as above, and for the liquid rubber component (Z-2), the amount of vinyl bonds was calculated in the same manner as above from the ratio of the peak area corresponding to the 1,2-bond unit of butadiene to the total peak area of the structural units derived from butadiene.
• Tg Glass transition temperature
• Unhydrogenated Block Copolymer (X-1) A nitrogen-purged and dried pressure-resistant vessel was charged with 62.4 kg of cyclohexane as a solvent and 0.0535 kg of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator, and the temperature was raised to 50° C., after which 1.40 kg of styrene (1) was added and polymerization was carried out for 1 hour, followed by addition of 12.79 kg of ⁇ -farnesene and polymerization for 2 hours, and further addition of 1.40 kg of styrene (2) and polymerization for 1 hour to obtain a polystyrene-poly( ⁇ -farnesene)-polystyrene triblock copolymer (hereinafter also referred to as “unhydrogenated block copolymer (X-1)”).
• Palladium carbon (palladium loading: 5% by mass) was added as a hydrogenation catalyst to this reaction liquid in an amount of 2.5% by mass relative to the triblock copolymer, and the reaction was carried out for 10 hours under conditions of a hydrogen pressure of 2 MPa and 150° C. After cooling and releasing the pressure, the palladium carbon was removed by filtration, and the filtrate was concentrated and further dried in vacuum to obtain a hydrogenated product of polystyrene-poly( ⁇ -farnesene)-polystyrene triblock copolymer (hereinafter also referred to as “hydrogenated block copolymer (X-2)”).
• X-2 hydrogenated block copolymer
• Hydrogenated Block Copolymer (X-3) A hydrogenated product of polystyrene-poly( ⁇ -farnesene)-polystyrene triblock copolymer (hereinafter also referred to as "hydrogenated block copolymer (X-3)") was obtained in the same manner as in Production Example 2, except that palladium carbon (palladium loading: 5 mass%) was used as a hydrogenation catalyst in the hydrogenation in an amount of 5 mass% relative to the triblock copolymer.
• palladium carbon palladium loading: 5 mass%
• Unhydrogenated Block Copolymer (X-4) A nitrogen-purged and dried pressure-resistant vessel was charged with 62.4 kg of cyclohexane as a solvent and 0.0535 kg of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator, and the temperature was raised to 50° C., after which 1.40 kg of styrene (1) was added and polymerization was carried out for 1 hour, and subsequently 6.40 kg of ⁇ -farnesene was added and polymerization was carried out for 2 hours to obtain a polystyrene-poly( ⁇ -farnesene) diblock copolymer (hereinafter also referred to as “unhydrogenated block copolymer (X-4)”).
• Unhydrogenated Block Copolymer (X-5) A nitrogen-purged and dried pressure-resistant vessel was charged with 62.4 kg of cyclohexane as a solvent and 0.0460 kg of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator, and the temperature was raised to 50° C., after which 2.34 kg of styrene (1) was added and polymerization was carried out for 1 hour, followed by addition of 10.92 kg of ⁇ -farnesene and polymerization for 2 hours, and further addition of 2.34 kg of styrene (2) and polymerization for 1 hour to obtain a polystyrene-poly( ⁇ -farnesene)-polystyrene triblock copolymer (hereinafter also referred to as “unhydrogenated block copolymer (X-5)”).
• the unhydrogenated block copolymer (X-1) of Production Example 1 the hydrogenated block copolymer (X-2) of Production Example 2, the hydrogenated block copolymer (X-3) of Production Example 3, the unhydrogenated block copolymer (X-4) of Production Example 4, and the unhydrogenated block copolymer (X-5) of Production Example 5 all have structural units derived from ⁇ -farnesene.
• the vinyl bond amount of polymer block (B-1) is also the vinyl bond amount of polymer block (B).
• the unhydrogenated block copolymer (X-1), the hydrogenated block copolymer (X-2), the hydrogenated block copolymer (X-3), and the unhydrogenated block copolymer (X-5) have a polystyrene-poly( ⁇ -farnesene)-polystyrene triblock skeleton.
• the unhydrogenated block copolymer (X-4) has a polystyrene-poly( ⁇ -farnesene) diblock skeleton and has a smaller weight average molecular weight than the above (X-1), (X-2), (X-3), and (X-5).
• the unhydrogenated block copolymers (X-1), (X-4) and (X-5) are not hydrogenated, the hydrogenated block copolymer (X-2) has a hydrogenation rate of less than 50 mol%, and the hydrogenated block copolymer (X-3) has a hydrogenation rate of 50 mol% or more.
• the unhydrogenated liquid rubber (Z-1) of Production Example 6 has a polyfarnesene structure and is found to have a high bio-based content.
• the vinyl bond amount is small and the melt viscosity at 38°C is also small, it is found that it is easy to disperse uniformly in the pressure-sensitive adhesive composition of the present invention and to easily improve the coatability.
• the non-hydrogenated liquid rubber (Z-2) of Production Example 7 has a polybutadiene structure and does not contain any naturally derived components, so it is found that it is difficult to increase the bio-based content of the adhesive composition.
• Biobased Degree The biobased degree of each component used to prepare the pressure-sensitive adhesive composition and each pressure-sensitive adhesive composition was measured in accordance with ASTM D6866-21. Specifically, each of the above components was combusted, and the amount of CO2 generated by the combustion was quantified. The quantified CO2 was measured for its 14C concentration using an accelerator mass spectrometer (AMS). The 14C concentration in the atmospheric CO2 was then compared with the measured 14C concentration to calculate the biobased degree. The biobased degree of each pressure-sensitive adhesive composition was calculated from the following formula based on the mass ratio of the block copolymer (X), the tackifier (Y), and the plasticizer (Z) used in the above Examples and Comparative Examples, and the biobased degree of each component.
• AMS accelerator mass spectrometer
• Biobased degree of pressure-sensitive adhesive composition (mass%) (X1 ⁇ X2/100)+(Y1 ⁇ Y2/100)+(Z1 ⁇ Z2/100)
• X1 represents the mass ratio (mass%) of the block copolymer (X) relative to the total mass of the adhesive composition
• Y1 represents the mass ratio (mass%) of the tackifier (Y) relative to the total mass of the adhesive composition
• Z1 represents the mass ratio (mass%) of the plasticizer (Z) relative to the total mass of the adhesive composition
• X2 (mass%) represents the biobased degree of the block copolymer (X)
• Y2 (mass%) represents the biobased degree of the tackifier (Y)
• Z2 (mass%) represents the biobased degree of the plasticizer (Z).
• Coating Film Thickness The coating film thickness of the pressure-sensitive adhesive composition prepared in the Examples and Comparative Examples was measured using a digital thickness meter (product name SMD-565J-L, manufactured by TECLOOK Corporation).
• SAFT Surface Acoustic Failure Temperature
• Examples A1 to A9 and Comparative Examples CA1 to CA5 A solution was prepared by dissolving each component in the amount shown in Table 3 in cyclohexane. Next, cyclohexane was further added to the above solution to adjust the solid content concentration (TS) to 25 mass%, thereby preparing a pressure-sensitive adhesive composition for coating that was diluted to a ratio of 20 parts by mass per 60 parts by mass of cyclohexane.
• the TS of a pressure-sensitive adhesive composition diluted with a solvent means the concentration of solids (the total of the block copolymer, tackifier, and plasticizer) in the pressure-sensitive adhesive composition diluted with the solvent.
• This pressure-sensitive adhesive composition for coating was applied onto a polyethylene terephthalate (PET) film at a speed of 50 mm/sec using an automatic coater (PI-1020 AUTO FILM APPLICATOR, manufactured by Tester Sangyo Co., Ltd.), and then dried by heating at 60° C. for 30 minutes to form a coating film of the pressure-sensitive adhesive composition having a thickness of 20 ⁇ m.
• PET polyethylene terephthalate
• the adhesive compositions of Examples A1 to A9 have a high bio-based content, high 180° peel strength, and good adhesive properties.
• the SAFT values are 100°C or higher, which indicates that they have high heat resistance.
• the adhesive compositions of Comparative Examples CA2 and CA3 have smaller SAFT and 180° peel strength values and are therefore inferior in heat resistance and adhesive property compared to the adhesive composition of Example A3, which has the same composition except that a "hydrogenated block copolymer having a hydrogenation rate of 50 mol% or more" or an "unhydrogenated block copolymer not containing a structural unit derived from farnesene" is used as the block copolymer.
• the adhesive composition of Comparative Example CA5 has smaller SAFT and 180° peel strength values and is therefore inferior in heat resistance and adhesive properties compared to the adhesive composition of Example A1, which has the same composition except that the block copolymer used is an "unhydrogenated block copolymer not containing a structural unit derived from farnesene".
• the adhesive composition of Comparative Example CA1 has a smaller 180° peel strength value and is inferior in adhesiveness compared to the adhesive compositions of Examples A1 and A5, which have the same composition except for using a "hydrogenated block copolymer having a hydrogenation rate of 50 mol % or more" as the block copolymer.
• the adhesive composition of Comparative Example CA4 has a smaller 180° peel strength value and is inferior in adhesive properties compared to the adhesive composition of Example A8, which has the same composition except that a "hydrogenated block copolymer having a hydrogenation rate of 50 mol % or more" was used as the block copolymer.
• Examples B1 to B9, Comparative Examples CB1 to CB2 A solution was prepared by dissolving each component in the amount shown in Table 4 in cyclohexane. Next, cyclohexane was further added to the above solution to adjust the solid content (TS) to 25 mass %, thereby preparing a pressure-sensitive adhesive composition for coating that was diluted to a ratio of 20 parts by mass per 60 parts by mass of cyclohexane.
• This pressure-sensitive adhesive composition for coating was applied onto a polyethylene terephthalate (PET) film at a speed of 50 mm/sec using an automatic coater (PI-1020 AUTO FILM APPLICATOR, manufactured by Tester Sangyo Co., Ltd.), and then heated and dried at 60° C. for 30 minutes to form a coating film of the pressure-sensitive adhesive composition having a thickness of 20 ⁇ m.
• PET polyethylene terephthalate
• the coating film was irradiated with UV light (wavelength 365 nm) at an irradiation dose of 300 mJ/cm 2 , 500 mJ/cm 2 or 1,000 mJ/cm 2 under an oxygen atmosphere using an F300S&LC-6B UV conveyor system (manufactured by Heraeus) to crosslink the pressure-sensitive adhesive composition.
• the adhesive compositions of Examples B1 to B9 have a high biobased content and are crosslinked, and therefore have a significantly increased SAFT value and high heat resistance compared to the adhesive compositions of Examples A1 to A9 described above.
• the adhesive compositions of Examples B2 to B4 and Example B1 when the UV light irradiation amount is 300 and 500 mJ/ cm2 have high 180° peel strength and good adhesive properties.
• the adhesive compositions of Examples B5, B6, B7, B8, B9 and Example B1 when the UV light irradiation amount is 1,000 mJ/ cm2 have low 180° peel strength, but have a predetermined value of 2.5 N/25 mm or more.
• the SAFT value when the UV light irradiation amount was 300 mJ/ cm2 was lower than the SAFT values when the UV light irradiation amount was 500 and 1,000 mJ/ cm2 , but was higher than the SAFT values of the pressure-sensitive adhesive compositions of Examples A1 to A9 described above, and it can be understood that crosslinking can be advanced to some extent even with a small UV light irradiation amount.
• the adhesive composition of Comparative Example CB1 has a significantly smaller SAFT value after UV irradiation at 300 and 500 mJ/ cm2 than the adhesive composition of Example B1, which has the same composition except that a "hydrogenated block copolymer with a hydrogenation rate of 50 mol% or more" is used as the block copolymer.
• a "hydrogenated block copolymer with a hydrogenation rate of 50 mol% or more" is used as the block copolymer.
• crosslinking is difficult to proceed when the UV irradiation amount is small compared to Example B1.
• the SAFT value is small even after UV irradiation at 1,000 mJ/ cm2 , and it is found to have poor heat resistance.
• the adhesive composition of Comparative Example CB2 has smaller SAFT value and 180° peel strength value after UV irradiation at 1,000 mJ/ cm2 than the adhesive composition of Example B1, which has the same composition except that the block copolymer used is an "unhydrogenated block copolymer not containing a structural unit derived from farnesene", and is therefore inferior in heat resistance and adhesive properties.
• Examples C1 to C5 and Comparative Examples CC1 to CC5 A solution was prepared by dissolving each component in the amount shown in Table 5 in cyclohexane. Next, cyclohexane was further added to the above solution to adjust the solid content (TS) to 25 mass %, thereby preparing a pressure-sensitive adhesive composition diluted to a ratio of 20 parts by mass to 60 parts by mass of cyclohexane. 10 g of this pressure-sensitive adhesive composition was poured into a release paper box measuring W 5 cm x D 5 cm x H 2 cm, air-dried at room temperature for 48 hours, and then further dried at 60°C for 2 hours to prepare a sheet having a thickness of 1 mm.
• the adhesive compositions of Examples C1 to C5 have relatively small haze values, and it can be seen that the compatibility between the block copolymer and the tackifier is high.
• the adhesive compositions of Comparative Examples CC1 to CC5 have a larger haze value than the adhesive compositions of Examples C1 to C5, which have the same composition except that a "hydrogenated block copolymer with a hydrogenation rate of 50 mol % or more" was used as the block copolymer, and it is clear that the compatibility between the block copolymer and the tackifier is low.
• Examples D1 to D5 and Comparative Examples CD1 to CD2 A solution was prepared by dissolving each component in the amount shown in Table 6 in cyclohexane. Next, cyclohexane was further added to the solution to adjust the solid content (TS) to 25 mass %, thereby preparing a composition diluted to a ratio of 20 parts by mass per 60 parts by mass of cyclohexane. This composition was then air-dried at room temperature for 48 hours, and then further dried at 60°C for 2 hours to prepare a pressure-sensitive adhesive composition. The adhesive compositions of Examples D1 to D5 and Comparative Examples CD1 to CD2 thus prepared were measured for bio-based content and melt viscosity at 180° C. by the above-mentioned procedures. The measurement results are shown in Table 6 together with the compositions.
• the adhesive compositions of Examples D1 to D5 have a high bio-based content, a low melt viscosity at 180°C, and good fluidity when heated to 180°C, making them suitable for use as hot melt adhesive compositions.
• Comparative Examples CD1 and CD2 have a higher melt viscosity at 180°C than those of the Examples, and are inferior in fluidity when heated to 180°C to the adhesive compositions of the Examples.
• each adhesive composition was prepared using a solvent, but each adhesive composition may also be prepared by melt-kneading the components in the amounts shown in Table 6. In this case, the same measurement results as described above are obtained.
• Examples E1 to E6 and Comparative Examples CE1 to CE3 A solution was prepared by dissolving each component in the amount shown in Table 7 in cyclohexane. Next, cyclohexane was further added to the above solution to adjust the solid content (TS) to 25 mass %, thereby preparing a pressure-sensitive adhesive composition for coating that was diluted to a ratio of 20 parts by mass per 60 parts by mass of cyclohexane.
• This pressure-sensitive adhesive composition for coating was applied onto a polyethylene terephthalate (PET) film at a speed of 50 mm/sec using an automatic coater (PI-1020 AUTO FILM APPLICATOR, manufactured by Tester Sangyo Co., Ltd.), and then dried by heating at 60° C. for 30 minutes to form a coating film of the pressure-sensitive adhesive composition having a thickness of 20 ⁇ m.
• PET polyethylene terephthalate
• the coating film was irradiated with UV light (wavelength 365 nm) at an irradiation dose of 300 mJ/cm 2 or 1,000 mJ/cm 2 under an oxygen atmosphere using an F300S&LC-6B UV conveyor system (manufactured by Heraeus) to crosslink the pressure-sensitive adhesive composition.
• the pressure-sensitive adhesive compositions of Examples E1 to E6 have slightly lower SAFT values when the irradiation dose is 300 mJ/ cm2 , and this tendency is somewhat stronger when the content of the crosslinking agent is small. However, they show high SAFT values at any UV irradiation dose and crosslinking agent content, and it can be understood that crosslinking can be adequately promoted with a small UV irradiation dose.
• the adhesive compositions of Comparative Examples CE1 to CE3 have lower SAFT values when the UV irradiation amount is 300 mJ/ cm2 compared to when the UV irradiation amount is 1,000 mJ/ cm2 , and it can be seen that this tendency becomes more pronounced when the content of the crosslinking agent is small.
• the adhesive compositions of Comparative Examples CE1 to CE3 have lower SAFT values at the same irradiation amount, and the degree of decrease in the SAFT value at an irradiation amount of 300 mJ/ cm2 is greater than the SAFT value at an irradiation amount of 1,000 mJ/ cm2 .
• Example F1 and Comparative Example CF1 A pressure-sensitive adhesive composition (Example F1) was prepared in the same manner as in Example B1, except that in Example B1, the same mass of 1,6-bis(acryloyloxy)hexane was used as the crosslinking agent instead of tris(mercaptoacetic acid)trimethylolpropane.
• a pressure-sensitive adhesive composition (Comparative Example CF1) was prepared in the same manner as in Comparative Example CB1, except that, in place of tris(mercaptoacetic acid)trimethylolpropane in the above-mentioned Comparative Example CB1, the same mass of 1,6-bis(acryloyloxy)hexane was used as the crosslinking agent.
• This adhesive composition for coating was applied to a polyethylene terephthalate (PET) film at a speed of 50 mm/sec using an automatic coater (PI-1020 AUTO FILM APPLICATOR, manufactured by Tester Sangyo Co., Ltd.), and then the film was dried by heating at 60°C for 30 minutes to form a coating film of the adhesive composition with a thickness of 20 ⁇ m.
• PET polyethylene terephthalate
• PI-1020 AUTO FILM APPLICATOR manufactured by Tester Sangyo Co., Ltd.
• test pieces were prepared by attaching an oxygen barrier film (a PET film manufactured by Toyobo Co., Ltd., thickness 50 ⁇ m) to the coating film. A number of test pieces were also prepared without the oxygen barrier film attached. These test pieces were then irradiated with UV light (wavelength 365 nm) at the irradiation dose shown in Table 8 below using an F300S&LC-6B UV conveyor system (manufactured by Heraeus) to crosslink the adhesive composition. Note that the UV light irradiation was performed through the oxygen barrier film for the test pieces with the oxygen barrier film attached, and directly on the adhesive composition for the test pieces without the oxygen barrier film.
• UV light wavelength 365 nm
• the coating film crosslinked with the adhesive composition of Example F1 has a high SAFT value, and it is understood that an adhesive layer with high heat resistance can be obtained even when 1,6-bis(acryloyloxy)hexane, an acrylic crosslinking agent, is used.
• the SAFT value becomes high even with a small amount of irradiation compared to the case of irradiating UV light without an oxygen barrier film (i.e., in the presence of oxygen).
• the 180° peel strength of the adhesive composition of Example F1 is equivalent to the 180° peel strength (19 N/25 mm) of the adhesive composition of Example A1 shown in Table 3, but when an oxygen barrier film is attached and irradiated with UV light, it is understood that the 180° peel strength becomes very small as shown in Table 8. Therefore, it can be understood that the adhesive composition can be easily peeled off from the adherend by reducing the adhesiveness by light irradiation when necessary, and is very suitable for use as a dicing tape, for example.
• the coating film obtained by crosslinking the pressure-sensitive adhesive composition of Comparative Example CF1 using the hydrogenated block copolymer (X-3), which is a hydrogenated block copolymer having a hydrogenation rate of 50% or more has a smaller SAFT value and is therefore inferior in heat resistance compared to Example F1.
• the adhesive composition of the present invention has a high biobased content and is provided with moderate adhesiveness and high heat resistance. Therefore, it can be formed to cover various articles, such as paper products, packaging materials, laminated wood panels, kitchen countertops, vehicles, labels, paper diapers, hospital pads, feminine sanitary napkins, surgical drapes, tapes, cases, cartons, trays, medical devices, or bandages, either partially or entirely.
• adherends including a combination of adherends of the same material
• adherends metal, wood, paper, plastic, rubber, glass, stone, granite, marble, masonry, porcelain, ceramics, tiles, pottery, concrete, clay, sand, chalk, textiles, fabrics, nonwoven fabrics, leather, and composites thereof; sheets, strips, tapes, labels, tags, webs, discs, plates, films, and any molded articles.
• the adhesive composition of the present invention can be used as an adhesive layer of a dicing tape for temporarily fixing a workpiece, such as a semiconductor wafer or a semiconductor device.
• Dicing tape uses its adhesive properties to fix a workpiece to a support member such as a frame, and when irradiated with UV light, the adhesive properties decrease, allowing the tape to be easily peeled off from the workpiece.
• the adhesive composition of the present invention can also be used as a hot-melt adhesive composition that is reduced in viscosity by heating and adheres to the various adherends described above.

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• 2022
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