Classifications

• • 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
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/35—Heat-activated
• • 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
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]

Definitions

• the present invention relates to a hot melt adhesive composition and an adhesive tape.
• adhesive tapes are used for purposes such as joining various assembly parts.
• the adhesives used in double-sided adhesive tapes include acrylic adhesives and rubber adhesives, with acrylic adhesives being the most widely used.
• acrylic adhesives have the problem of low adhesion to olefin resin materials such as polyethylene and polypropylene, the amount of which has been increasing in recent years.
• Patent Document 1 discloses an adhesive composition having a base polymer that is a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound as a rubber-based adhesive.
• the present invention was made in consideration of these circumstances, and aims to provide a hot melt adhesive composition that exhibits minimal viscosity increase upon prolonged heating, can be suitably used for hot melt coating, and exhibits high adhesive strength to olefin resin materials in high temperature environments.
• a hot melt pressure-sensitive adhesive composition comprising a styrene-butadiene block copolymer and a tackifier, the styrene-butadiene block copolymer having a partially hydrogenated butadiene portion, and having a chemiluminescence emission intensity of less than 300,000 count/s 5 minutes after the start of measurement in an atmosphere at 185°C.
• the hot melt pressure sensitive adhesive composition according to [1] having a viscosity at 185°C of 10,000 to 100,000 mPa ⁇ s.
• the tackifier includes a first tackifier, and the first tackifier is at least one of a terpene resin that is liquid at 23°C and a rosin ester that is liquid at 23°C.
• the tackifier comprises a second tackifier, and the second tackifier has a softening point of 70 to 120°C.
• the tackifier comprises a first tackifier, a second tackifier, and a third tackifier, the first tackifier being a terpene resin that is liquid at 23°C, the second tackifier being a terpene resin having a softening point of 70 to 120°C, and the third tackifier being a terpene phenol resin having a softening point of 140°C or higher.
• the hot melt pressure-sensitive adhesive composition according to [8] containing 45 to 55 parts by mass of the styrene-butadiene block copolymer, 10 to 20 parts by mass of the first tackifier, 10 to 25 parts by mass of the second tackifier, and 17.5 to 27.5 parts by mass of the third tackifier, based on 100 parts by mass of the hot melt pressure-sensitive adhesive composition.
• a pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer containing the hot melt pressure-sensitive adhesive composition according to any one of [1] to [12].
• a hot melt adhesive composition containing a styrene-butadiene block copolymer in which the butadiene portion has been partially hydrogenated and a tackifier, and whose chemiluminescence emission intensity meets certain conditions exhibits little increase in viscosity when heated for long periods of time, and has good adhesion to olefin resin materials in high temperature environments, leading to the completion of the present invention.
• Hot melt adhesive composition contains a styrene-butadiene block copolymer and a tackifier.
• the tackifier means a tackifier, which is a thermoplastic resin that is liquid or solid at room temperature and is added to enhance adhesiveness.
• the styrene-butadiene block copolymer contained in the pressure-sensitive adhesive composition has a partially hydrogenated butadiene portion.
• the styrene-butadiene block copolymer according to the present invention means a block copolymer including a block having a styrene monomer unit and a block having a butadiene monomer unit.
• the styrene monomer unit is a structural unit (monomer unit) of the block and copolymer derived from styrene.
• the butadiene monomer unit is a structural unit (monomer unit) of the block and copolymer derived from butadiene.
• the content of styrene monomer units in 100% by mass of the styrene-butadiene block copolymer is preferably 24% by mass or more, and more preferably 24 to 40% by mass.
• the content of styrene monomer units is specifically, for example, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40% by mass, and may be within a range between any two of the values exemplified here.
• the content of butadiene monomer units in 100% by mass of the styrene-butadiene block copolymer is preferably 76% by mass or less, and more preferably 50 to 76% by mass.
• the content of the styrene monomer unit is, for example, 50, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, or 76% by mass, and may be within a range between any two of the values exemplified here.
• the resulting adhesive tape has appropriate adhesive strength and holding power to the adherend.
• the content of the styrene monomer unit and the butadiene monomer unit can be measured based on JIS K6383.
• the butadiene portion of the styrene-butadiene block copolymer is preferably hydrogenated by 20 to 90% by mass, and more preferably by 30 to 80% by mass.
• a specific example of a styrene-butadiene block copolymer in which the butadiene portion is partially hydrogenated is styrene-butadiene-butylene-styrene block copolymer (SBBS).
• the adhesive composition preferably contains, as the styrene-butadiene block copolymer, a triblock copolymer including block A containing monomer units derived from styrene, block B containing monomer units derived from butadiene, and block C containing monomer units derived from styrene.
• the adhesive composition according to the present invention preferably contains, as the styrene-butadiene block copolymer, a diblock copolymer including block A containing monomer units derived from styrene and block B containing monomer units derived from butadiene.
• the block B containing monomer units derived from butadiene is partially hydrogenated.
• the block B containing monomer units derived from butadiene has a butadiene block and a butylene block.
• the adhesive composition according to the present invention preferably contains 50 to 85 mass% of the diblock copolymer, and more preferably 55 to 80 mass%, when the total mass of the styrene-butadiene block copolymers contained in the adhesive composition is taken as 100 mass%.
• Specific examples of the content of the diblock copolymer include 50, 55, 60, 65, 70, 75, 80, and 85 mass%, and may be within a range between any two of the numerical values exemplified here. By setting the content of the diblock copolymer within the above numerical range, an adhesive composition with appropriate tack can be obtained.
• the styrene-butadiene block copolymer preferably contains component a having a peak top molecular weight of 200,000 or more and 400,000 or less in GPC measurement (gel permeation chromatography), and component b having a peak top molecular weight of 100,000 or more and less than 200,000.
• GPC measurement containing components a and b means that in the GPC spectrum obtained by GPC measurement, the peak has a top at a molecular weight position of 200,000 or more and 400,000 or less, and the peak has a top at a molecular weight position of 100,000 or more and less than 200,000.
• Component a is, for example, a component having a peak top molecular weight of 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000, 390,000, or 400,000, and may be within a range between any two of the numerical values exemplified here.
• Component b is, for example, a component having a peak top molecular weight of 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, 160,000, 170,000, 180,000, or 190,000, or a component less than 200,000, and may be within a range between any two of the numerical values exemplified here.
• an adhesive tape having an excellent balance of adhesion to olefin-based materials and adhesion at high temperatures can be obtained.
• the styrene-butadiene block copolymer may contain components other than components a and b in the GPC measurement.
• the styrene-butadiene block copolymer may further contain a component whose peak top molecular weight is 5,000 or more and less than 100,000, for example, a component of 5,000, 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, or a component less than 100,000, and may contain a component whose peak top molecular weight is within a range between any two of the numerical values exemplified here.
• a styrene-butadiene block copolymer having such a molecular weight distribution can be obtained, for example, by appropriately selecting and combining two or more types of styrene-butadiene block copolymers having different peak top molecular weights, weight average molecular weights, or molecular weight distributions.
• the adhesive composition can contain two or more types of styrene-butadiene block copolymers as the styrene-butadiene block copolymers.
• the adhesive composition can contain, as the styrene-butadiene block copolymers, a styrene-butadiene block copolymer A having a peak top molecular weight of 200,000 or more and 400,000 or less, and a styrene-butadiene block copolymer B having a peak top molecular weight of 100,000 or more and less than 200,000.
• the styrene-butadiene block copolymer A corresponds to the above component a
• the styrene-butadiene block copolymer B corresponds to the above component b.
• Styrene-butadiene block copolymer A has a partially hydrogenated butadiene portion, and the butadiene portion of styrene-butadiene block copolymer A is preferably hydrogenated by 20 to 90% by mass, and more preferably by 30 to 80% by mass.
• a specific example of a styrene-butadiene block copolymer in which the butadiene portion is partially hydrogenated is styrene-butadiene-butylene-styrene block copolymer (SBBS).
• SBBS styrene-butadiene-butylene-styrene block copolymer
• the hydrogenation rate can be determined by composition analysis using H-NMR, from the peak of hydrogenated butadiene and peaks derived from other monomer units.
• the adhesive composition preferably contains, as the styrene-butadiene block copolymer A, a triblock copolymer including a block ⁇ containing a monomer unit derived from styrene, a block ⁇ containing a monomer unit derived from butadiene, and a block ⁇ containing a monomer unit derived from styrene.
• the adhesive composition preferably contains, as the styrene-butadiene block copolymer A, a diblock copolymer including a block ⁇ containing a monomer unit derived from ⁇ -butadiene, which contains a monomer unit derived from styrene.
• the block ⁇ is partially hydrogenated, that is, it is preferable that the block ⁇ has a butadiene block and a butylene block.
• the styrene-butadiene block copolymer A preferably contains 50 to 85% by mass of the diblock copolymer, and more preferably contains 55 to 80% by mass.
• the content of the diblock copolymer is specifically, for example, 50, 55, 60, 65, 70, 75, 80, or 85% by mass, and may be within a range between any two of the numerical values exemplified here.
• Styrene-butadiene block copolymer A has a peak top molecular weight of 200,000 or more and 400,000 or less in GPC measurement, specifically, for example, the peak top molecular weight is 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000, 390,000, or 400,000, and may be within a range between any two of the numerical values exemplified here.
• the styrene-butadiene block copolymer A has an MFR (melt flow rate) measured at 200°C and 5 kgf of less than 10 g/10 min.
• the styrene-butadiene block copolymer A may have an MFR measured at 200°C and 5 kgf of, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 g/10 min, or less than 10 g/10 min, or may be within a range between any two of the values exemplified here.
• the styrene-butadiene block copolymer B has a partially hydrogenated butadiene portion, preferably 20 to 90% by mass, and more preferably 30 to 80% by mass.
• a specific example of a styrene-butadiene block copolymer having a partially hydrogenated butadiene portion is styrene-butadiene-butylene-styrene block copolymer (SBBS).
• the adhesive composition preferably contains, as the styrene-butadiene block copolymer B, a triblock copolymer including a block ⁇ containing monomer units derived from styrene, a block ⁇ containing monomer units derived from butadiene, and a block ⁇ containing monomer units derived from styrene.
• the adhesive composition preferably contains, as the styrene-butadiene block copolymer B, a diblock copolymer including a block ⁇ containing monomer units derived from ⁇ -butadiene, which contains monomer units derived from styrene.
• the block ⁇ is partially hydrogenated, that is, the block ⁇ containing monomer units derived from butadiene preferably has a butadiene block and a butylene block.
• the styrene-butadiene block copolymer B is taken as 100% by mass, the styrene-butadiene block copolymer B preferably contains 50 to 85% by mass, and more preferably 55 to 80% by mass, of the diblock copolymer.
• the content of the diblock copolymer is, for example, 50, 55, 60, 65, 70, 75, 80, or 85% by mass, and may be within a range between any two of the values exemplified here.
• the styrene-butadiene block copolymer B has a peak top molecular weight of 100,000 or more and less than 200,000 in GPC measurement, specifically, for example, a component with a peak top molecular weight of 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, 160,000, 170,000, 180,000, 190,000, or a component less than 200,000, and may be within a range between any two of the numerical values exemplified here.
• the styrene-butadiene block copolymer B preferably has an MFR of 10 g/10 min or more measured at 200°C and 5 kgf.
• the styrene-butadiene block copolymer B may have an MFR of, for example, 10, 12, 13, 14, 15, 16, 17, 18, 19, or 20 g/10 min measured at 200°C and 5 kgf, and may be within a range between any two of the values exemplified here.
• the styrene-butadiene block copolymer may be used alone or in combination of two or more types.
• two or more types of styrene-butadiene block copolymers having different peak top molecular weights, weight average molecular weights, molecular weight distributions, MFRs, content rates of monomer units derived from styrene, content rates of diblock copolymers, etc. may be used in combination.
• the terpene resin according to the present invention refers to a polymer of terpene, a copolymer of terpene and other monomers, and hydrogenated versions of these polymers.
• examples of such resins include terpene resin, aromatic modified terpene resin, terpene phenol resin, and hydrogenated terpene phenol resin.
• Terpene resins that are liquid at 23°C include YS Resin LP (aromatic modified terpene resin, flash point 220°C, manufactured by Yasuhara Chemical Co., Ltd.), Dimalon (liquid terpene resin, flash point 174°C, manufactured by Yasuhara Chemical Co., Ltd.), YS Resin CP (liquid terpene resin, flash point 178°C, manufactured by Yasuhara Chemical Co., Ltd.), YS Resin PX300N (terpene resin, flash point 202°C, manufactured by Yasuhara Chemical Co., Ltd.), and YS Polystar T30 (terpene phenol resin, flash point 205°C, manufactured by Yasuhara Chemical Co., Ltd.).
• YS Resin LP aromatic modified terpene resin, flash point 220°C, manufactured by Yasuhara Chemical Co., Ltd.
• Dimalon liquid terpene resin, flash point 174°C, manufactured by Yasuhara Chemical Co., Ltd
• YS Resin LP which has a high flash point, low heat loss, and high compatibility with styrene-butadiene block copolymers.
• the flash point of a terpene resin that is liquid at 23°C is preferably 180°C or higher, more preferably 200°C or higher, and even more preferably 210°C or higher.
• the viscosity of the first tackifier at 25°C is preferably 500 to 150,000 mPa ⁇ s, and more preferably 1,000 to 100,000 mPa ⁇ s.
• the viscosity at 25°C may be, for example, 500, 1,000, 2,000, 5,000, 10,000, 20,000, 50,000, 100,000, 120,000, or 150,000 mPa ⁇ s, or may be within a range between any two of the values exemplified here.
• the pressure-sensitive adhesive composition preferably contains a second tackifier.
• the second tackifier has a softening point of 70 to 120° C.
• the pressure-sensitive adhesive composition may contain one type of second tackifier alone or two or more types in combination.
• the softening point of the second tackifier is 70 to 120°C, preferably 80 to 120°C, and more preferably 90 to 115°C. Specific examples of the softening point are 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, and 120°C, and may be within a range between any two of the values exemplified here.
• the second tackifier for example, C9 petroleum resin, hydrogenated C9 petroleum resin, C5 petroleum resin, alicyclic petroleum resin, alicyclic/aromatic petroleum resin, rosin-based resin (polymerized rosin ester, modified polymerized rosin ester, stabilized rosin ester, etc.), terpene-based resin, etc. can be used.
• C9 petroleum resin hydrogenated C9 petroleum resin
• C5 petroleum resin alicyclic petroleum resin
• alicyclic/aromatic petroleum resin rosin-based resin (polymerized rosin ester, modified polymerized rosin ester, stabilized rosin ester, etc.), terpene-based resin, etc.
• rosin-based resin polymerized rosin ester, modified polymerized rosin ester, stabilized rosin ester, etc.
• terpene-based resin etc.
• the pressure-sensitive adhesive composition preferably contains a third tackifier.
• the third tackifier has a softening point of 140° C. or higher.
• the pressure-sensitive adhesive composition may contain the third tackifier alone or in combination of two or more kinds.
• the softening point of the third tackifier is 140°C or higher, preferably 140 to 180°C, and more preferably 160 to 170°C.
• Specific examples of the softening point include 140, 145, 150, 155, 160, 165, 170, 175, and 180°C, and may be within a range between any two of the values exemplified here.
• the third tackifier for example, C9 petroleum resin, hydrogenated C9 petroleum resin, C5 petroleum resin, alicyclic petroleum resin, alicyclic/aromatic petroleum resin, terpene resin, rosin resin (polymerized rosin ester, modified polymerized rosin ester, stabilized rosin ester, etc.), alkylphenol compound, etc., each having a softening point of 140°C or higher, can be used.
• the third tackifier it is preferable to use a terpene phenol resin from the viewpoint of an excellent balance between melt viscosity and high-temperature adhesive strength.
• the softening point of the tackifier can be defined as a value measured based on the softening point test method (ring and ball method) specified in JIS K5902 and JIS K2207. Specifically, the sample is melted as quickly as possible at the lowest possible temperature, and is carefully filled into a ring placed on a flat metal plate, taking care not to create bubbles. After cooling, the part that protrudes from the flat surface, including the top end of the ring, is cut off with a slightly heated knife. Next, a support (ring stand) is placed in a glass container (heating bath) with a diameter of 85 mm or more and a height of 127 mm or more, and glycerin is poured in to a depth of 90 mm or more.
• ring and ball method the softening point test method
• a steel ball (diameter 9.5 mm, weight 3.5 g) and the ring filled with the sample are immersed in glycerin without touching each other, and the temperature of the glycerin is kept at 20°C ⁇ 5°C for 15 minutes.
• the steel ball is placed in the center of the surface of the sample in the ring, and this is placed in a fixed position on the support.
• the distance from the top of the ring to the glycerin surface is kept at 50 mm, a thermometer is placed, and the center of the thermometer's mercury bulb is positioned at the same height as the center of the ring, and the container is heated.
• the flame of the Bunsen burner used for heating is placed halfway between the center of the bottom of the container and the edge, and heating is made uniform.
• the rate of increase in bath temperature after reaching 40°C from the start of heating can be set to 5.0 ⁇ 0.5°C per minute.
• the sample gradually softens and flows down from the ring, and the temperature is read when it comes into contact with the bottom plate, which can be regarded as the softening point. Two or more softening points can be measured at the same time, and the average value can be used.
• the softening point is about 50°C higher than the glass transition point of the tackifier
• the softening point can be estimated by detecting the Tg using a DSC (differential scanning calorimeter).
• DSC differential scanning calorimeter
• One method for identifying the softening point of a tackifier in an adhesive using this technique is to use preparative HPLC to isolate the tackifier components in the adhesive, measure the Tg from the DSC measurement results of this isolated sample, and estimate the softening point.
• the contents of the styrene-butadiene block copolymer, the first tackifier, the second tackifier, and the third tackifier in the pressure-sensitive adhesive composition are not particularly limited. As an example, by setting the contents of each component within the following ranges, a pressure-sensitive adhesive tape having even higher adhesive strength to olefin-based materials, particularly high adhesive strength at high temperatures, is likely to be obtained.
• the adhesive composition preferably contains 45 to 55 parts by mass of styrene-butadiene block copolymer when the adhesive composition is taken as 100 parts by mass.
• the content of the styrene-butadiene block copolymer is specifically, for example, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, or 55 parts by mass, and may be within a range between any two of the numerical values exemplified here.
• the adhesive composition preferably contains 10 to 20 parts by mass of the first tackifier when the adhesive composition is taken as 100 parts by mass.
• the content of the first tackifier is specifically, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 parts by mass, and may be within a range between any two of the numerical values exemplified here.
• the adhesive composition When the adhesive composition is taken as 100 parts by mass, the adhesive composition preferably contains 10 parts by mass or more of the second tackifier, more preferably 10 to 40 parts by mass, and even more preferably 10 to 25 parts by mass.
• the content of the second tackifier is specifically, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40 parts by mass, and may be within a range between any two of the numerical values exemplified here.
• the adhesive composition When the adhesive composition is taken as 100 parts by mass, the adhesive composition preferably contains 10 to 30 parts by mass of the third tackifier, and more preferably 17.5 to 27.5 parts by mass.
• the content of the third tackifier is specifically, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 parts by mass, and may be within a range between any two of the numerical values exemplified here.
• the adhesive composition preferably contains a first tackifier, a second tackifier, and a third tackifier as tackifiers, the first tackifier being a terpene resin that is liquid at 23°C, the second tackifier being a terpene resin with a softening point of 70 to 120°C, and the third tackifier being a terpene phenol resin with a softening point of 140°C or higher.
• the adhesive composition preferably contains 45 to 55 parts by mass of a styrene-butadiene block copolymer, 10 to 20 parts by mass of a first tackifier, 10 to 25 parts by mass of a second tackifier, and 17.5 to 27.5 parts by mass of a third tackifier, when the adhesive composition is taken as 100 parts by mass.
• the content ratio of the first tackifier to the second tackifier is preferably 1:0.5 to 1:1.5 by mass.
• the pressure-sensitive adhesive composition according to the present invention may contain various additives such as a plasticizer, an antioxidant, an ultraviolet absorber, a stabilizer, a filler, a modifier, etc., within a range that does not impair the effects of the present invention.
• the pressure-sensitive adhesive composition may contain a plasticizer.
• plasticizer include phthalate ester plasticizers, polybutene, paraffin-based process oil, naphthene-based process oil, aromatic process oil, liquid paraffin, and hydrocarbon synthetic oil.
• the pressure-sensitive adhesive composition preferably contains an antioxidant, which makes it easier to control the chemiluminescence emission intensity of the pressure-sensitive adhesive composition (described later) to a suitable value.
• the antioxidant include 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 2,4-bis(octylthiomethyl)-o-cresol, 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2,4-di-t-amyl-6-[1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate, 2,4
• the antioxidant preferably has a melting point of 60°C or higher, and more preferably 80°C or higher.
• the upper limit of the antioxidant's melting point is not particularly limited, but is, for example, 300°C or lower. When the antioxidant's melting point is within the above range, the antioxidant is unlikely to liquefy in a high-temperature environment, which makes it possible to suppress a decrease in the adhesive strength of the adhesive composition in a high-temperature environment.
• UV absorber examples include benzotriazole-based ultraviolet absorbers such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-t-butylphenyl)benzotriazole, and 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole, benzophenone-based ultraviolet absorbers such as 2-hydroxy-4-methoxybenzophenone, salicylic acid ester-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and hindered amine-based light stabilizers. These can be used alone or in combination.
• benzotriazole-based ultraviolet absorbers such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-t-butylphenyl)benzotriazole, and 2-(2'-hydroxy-3',5'-di-t-butylphenyl)
• the content of the antioxidant relative to 100 parts by mass of the adhesive composition is, for example, 0.05 to 5 parts by mass, preferably 0.1 to 3.5 parts by mass, and more preferably 0.1 to 0.5 parts by mass.
• Specific examples of the content of the antioxidant are 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 parts by mass, and may be within a range between any two of the numerical values exemplified here.
• filler examples include calcium carbonate, kaolin, talc, titanium oxide, mica, styrene beads, silica, etc. These particulate fillers can be used alone or in combination.
• the pressure-sensitive adhesive composition according to the present invention has a chemiluminescence emission intensity of less than 300,000 counts/s 5 minutes after the start of measurement in an atmosphere at 185° C.
• Pressure-sensitive adhesive compositions having a chemiluminescence emission intensity in this range have a small increase in viscosity due to long-term heating and good adhesion to olefin-based resin materials in high-temperature environments.
• the chemiluminescence emission intensity of the pressure-sensitive adhesive composition can be controlled by appropriately selecting the types of components of the pressure-sensitive adhesive composition and adjusting the amounts of the components.
• Chemiluminescence is a weak light that is generated when molecules in a chemical reaction system return from an excited state to the ground state, emitting the difference in energy as photons. Chemiluminescence emission intensity is measured by detecting this light. An example of a specific method for measuring chemiluminescence emission intensity 5 minutes after the start of measurement in an atmosphere of 185°C is shown below.
• the adhesive composition is placed in the sample chamber of a chemiluminescence measuring device (Tohoku Electronics Industry Co., Ltd., CLA-FS4) that has a photomultiplier tube as the detection element, which has been preheated to 185°C, and measurement of the chemiluminescence emission intensity is started while air with an oxygen concentration of 20% is sent into the sample chamber at 50 ml/min.
• the chemiluminescence emission intensity (unit: count/s) is measured 5 minutes after the start of measurement.
• the chemiluminescence emission intensity of the adhesive composition may be measured by placing an adhesive tape having an adhesive layer made of the adhesive composition in a sample chamber of a chemiluminescence measuring device with the adhesive layer (adhesive surface) facing upwards.
• the chemiluminescence emission intensity 5 minutes after the start of measurement in an atmosphere at 185°C is preferably less than 200,000 counts/s, and more preferably less than 150,000 counts/s.
• the lower limit of the chemiluminescence emission intensity is not particularly limited, but is, for example, 1000 counts/s or more.
• the chemiluminescence emission intensity may be, for example, less than 1,000, 5,000, 10,000, 20,000, 30,000, 40,000, 50,000, 100,000, 150,000, 200,000, 250,000, or 300,000 counts/s, and may be within a range between any two of the numerical values exemplified here.
• the adhesive composition preferably has a melt viscosity at 185°C of 10,000 to 100,000 mPa ⁇ s, more preferably 15,000 to 90,000 mPa ⁇ s.
• the melt viscosity is specifically, for example, 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, or 100,000 mPa ⁇ s, and may be within a range between any two of the values exemplified here.
• the adhesive composition preferably has an initial viscosity ⁇ 0 at 185°C of 10,000 to 100,000 mPa ⁇ s, more preferably 15,000 to 90,000 mPa ⁇ s.
• the initial viscosity refers to the melt viscosity when the adhesive composition is heated at 185°C for a short period of time, within 5 minutes.
• the adhesive composition preferably has a difference ( ⁇ 1- ⁇ 0) between the melt viscosity ⁇ 1 and the initial viscosity ⁇ 0 when heated at 185°C for 30 minutes, of 0 to 20,000 mPa ⁇ s, more preferably 0 to 10,000 mPa ⁇ s, and even more preferably 0 to 5,000 mPa ⁇ s. In this case, the degree of thickening of the adhesive composition due to long-term heating is small, making it possible to perform stable hot melt coating.
• the melt viscosity at 185°C and the initial viscosity can be controlled by appropriately selecting the types of components of the adhesive composition and adjusting the amounts of those components.
• the viscosity of the adhesive composition can be measured at 185°C or room temperature using a rheometer at a shear rate of 10 (1/s).
• the manufacturing method of the adhesive composition is not particularly limited.
• the manufacturing method of the adhesive composition according to the present embodiment may include a tackifier kneading step in which raw materials such as a first tackifier, a second tackifier, and a third tackifier are kneaded with a kneader.
• an antioxidant and a plasticizer may be further added.
• kneading may be performed, for example, for 3 to 30 minutes at 5 to 25 rpm.
• the manufacturing method of the adhesive composition may further include a block copolymer addition/kneading step in which a styrene-butadiene block copolymer is added and kneaded after the tackifier etc. kneading step.
• kneading may be performed, for example, for 20 to 200 minutes at 5 to 25 rpm.
• Adhesive Tape The adhesive tape according to the present invention comprises an adhesive layer containing the above-mentioned adhesive composition.
• the adhesive layer is formed by heating and melting the adhesive composition and hot-melt coating the substrate. That is, the manufacturing method of the adhesive tape includes a coating step of hot-melt coating the adhesive composition on the substrate to form an adhesive layer.
• the adhesive tape includes an adhesive layer and a substrate layer composed of a substrate.
• the adhesive tape can be manufactured with less energy, cost and time than the method of dissolving the adhesive composition in a solvent, coating and drying the adhesive composition.
• the coating method a known method can be used, and a non-contact coating method or a contact method can be adopted. An example of the non-contact coating method can be cross-coating. An example of the contact method can be slot die coating.
• the thickness of the adhesive layer is not particularly limited, but is preferably 40 to 100 ⁇ m. Specific examples of the thickness of the adhesive layer are 40, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100 ⁇ m, and may be within a range between any two of the numerical values exemplified here.
• the adhesive composition according to the present invention can be applied by a hot melt method, so that a relatively thick adhesive layer can be formed with less energy, cost, and time than a method in which the adhesive composition is dissolved in a solvent, applied, and dried.
• the type of substrate is not particularly limited, but for example, a nonwoven fabric or a resin film can be used.
• the adhesive tape may also be a double-sided adhesive tape having an adhesive layer composed of an adhesive composition on both sides of the substrate. In this case, it is preferable that the double-sided adhesive tape has an adhesive layer of the above thickness on both sides of the substrate.
• a release film may also be attached to the surface of the adhesive layer of the double-sided adhesive tape opposite the surface that contacts the substrate.
• the adhesive tape has an adhesive strength of 10 N/10 mm or more against a SUS adherend at 23° C. based on JIS Z0237, more preferably 15 N/10 mm or more, and even more preferably 17 N/10 mm or more.
• the adhesive strength is specifically, for example, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 N/10 mm, and may be within a range between any two of the values exemplified here.
• the adhesive strength can be controlled by adjusting the type and amount of the components of the adhesive composition.
• the adhesive strength can be determined by measuring the 180° peel adhesive strength against the adherend in a 23° C. atmosphere based on JIS Z0237 "10. Adhesive strength".
• the peel distance of the adhesive tape measured by a constant-load peeling test at 80°C is preferably 50 mm or less, more preferably 45 mm or less, and even more preferably 40 mm or less.
• the peel distance of the adhesive tape may be, for example, 0, 10, 20, 30, 35, 40, 45, or 50 mm, and may be within a range between any two of the values exemplified here.
• the constant-load peeling test is performed, for example, as follows. The adhesive tape is attached to a polypropylene adherend and treated in an 80°C atmosphere for 10 minutes.
• a load (100 gf) is applied to the end of the adhesive tape perpendicular to the surface of the adherend and in a direction away from the adherend, and the peel distance of the adhesive sheet after 30 minutes is measured.
• the block copolymers used in the examples and comparative examples are as follows.
• Asaprene N521 manufactured by Asahi Kasei Corporation
• SBBS a styrene-butadiene-butylene-styrene block copolymer, which is a styrene-butadiene block copolymer in which the butadiene portion is partially hydrogenated
• styrene content 25% by mass diblock content 60% by mass
• MFR 2 g/10 min MFR 2 g/10 min.
• GPC measurement it has peaks for the peak top molecular weights of two components (235,000 and 79,000).
• Tuftec P1500 manufactured by Asahi Kasei Corporation: SBBS (a styrene-butadiene-butylene-styrene block copolymer, which is a styrene-butadiene block copolymer in which the butadiene portion is partially hydrogenated), styrene content 30% by mass, diblock content 65% by mass, MFR 15 g/10 min. In GPC measurement, it has peaks for the peak top molecular weights of three components (125,000, 65,000, 13,000).
• Tuftec P1083 manufactured by Asahi Kasei Corporation: SBBS (a styrene-butadiene-butylene-styrene block copolymer, which is a styrene-butadiene block copolymer in which the butadiene portion is partially hydrogenated), styrene content 20% by mass, diblock content 80% by mass, MFR 10 g/10 min. In GPC measurement, it has peaks for the peak top molecular weights of three components (110,000, 50,000, 8,000).
• Quintac 3421 (manufactured by Zeon Corporation): SIS (styrene-isoprene-styrene block copolymer)
• the molecular weight in the GPC measurement is a polystyrene-equivalent molecular weight, and the MFR is a value measured at 200° C. and 5 kgf.
• the first tackifiers used in the examples and comparative examples are as follows.
• YS Resin LP manufactured by Yasuhara Chemical Co., Ltd.
• Aromatic modified terpene resin that is liquid at 23°C, with a flash point of 220°C and a viscosity of 2,000 mPa ⁇ s at 25°C.
• the second tackifiers used in the examples and comparative examples are as follows.
• YS Resin PX1150N manufactured by Yasuhara Chemical Co., Ltd.
• terpene resin softening point 115°C Alcon P-110 (manufactured by Arakawa Chemical Industries, Ltd.): hydrogenated C9 petroleum resin, softening point 110°C Petrotac 90 (manufactured by Tosoh Corporation): C5/C9 petroleum resin, softening point 90°C ESCOREZ1310 (manufactured by ExxonMobil Chemical Company): C5 petroleum resin, softening point 93°C
• the third tackifier used in the examples and comparative examples is as follows.
• P-140 manufactured by Arakawa Chemical Industries, Ltd.: hydrogenated C9 petroleum resin, softening point 141°C YS Polystar T-145 (manufactured by Yasuhara Chemical Co., Ltd.): terpene phenol resin, softening point 145°C YS Polystar T-160 (manufactured by Yasuhara Chemical Co., Ltd.): terpene phenol resin, softening point 160°C DS-822 (Harima Chemical Group Co., Ltd.): Polymerized rosin ester, softening point 165°C
• the antioxidants used in the examples and comparative examples are as follows. Irganox 1010 (manufactured by BASF Japan Ltd.): melting point 110°C Irganox 1726 (manufactured by BASF Japan Ltd.): melting point 28°C Irganox 1035 (manufactured by BASF Japan Ltd.): melting point 63°C Irganox 1024 (manufactured by BASF Japan Ltd.): melting point 225°C Sumilizer GS (Sumitomo Chemical Co., Ltd.): melting point 119°C Sumilizer GP (Sumitomo Chemical Co., Ltd.): melting point 115°C or higher
• the initial viscosity ⁇ 0 of the resulting adhesive composition at 185°C and the melt viscosity ⁇ 1 after heating at 185°C for 30 minutes were measured using a rheometer (Anton Paar, MCR302) at a shear rate of 10 [1/s]. The measurement results are shown in Tables 1 to 3.
• the prepared pressure-sensitive adhesive composition was heated to 200° C. in a melter to melt it, and then coated to a thickness of 80 ⁇ m on one side of a substrate (PET film, manufactured by Toray Industries, Inc., product number Lumirror T60 50 ⁇ m) using a slot die coater (manufactured by Nordson Chemical) to form a pressure-sensitive adhesive layer, thereby producing a pressure-sensitive adhesive tape.
• a substrate manufactured by Toray Industries, Inc., product number Lumirror T60 50 ⁇ m
• a slot die coater manufactured by Nordson Chemical
• the chemiluminescence emission intensity of the adhesive composition was measured 5 minutes after the start of measurement in an atmosphere at 185°C.
• the adhesive tape was punched out to a size of 20 mm wide and 50 mm long, and placed with the adhesive layer facing upwards in the sample chamber of a chemiluminescence measuring device (Tohoku Electronics Industries Co., Ltd., CLA-FS4) whose detection element is a photomultiplier tube that had been preheated to 185°C, and measurement was started while air with an oxygen concentration of 20% was sent into the sample chamber at 50 ml/min.
• the measurement results of the chemiluminescence emission intensity 5 minutes after the start of measurement are shown in Tables 1 to 3.
• the adhesive strength (180° peel adhesive strength) of the adhesive tape to a SUS adherend in an atmosphere of 23° C. was measured. First, the adhesive tape was punched out to a width of 20 mm and a length of 200 mm, and the adhesive surface was attached to the adherend by pressure bonding. Then, the 180° peel strength was measured using a tensile tester in an atmosphere of 23° C. at a tensile speed of 300 mm/min. The measurement results are shown in Tables 1 to 3.
• the hot melt coatability of the pressure-sensitive adhesive composition was evaluated.
• the pressure-sensitive adhesive composition was heated to 200° C. in a melter to melt it, and discharged for 30 minutes using a slot die coater (manufactured by Nordson Corporation).
• the change in the discharge amount 30 minutes after the start of discharge was evaluated according to the following criteria.
• the evaluation results are shown in Tables 1 to 3. ⁇ : The discharge amount after 30 minutes from the start of discharge is reduced by less than 10% compared to the time when discharge started. ⁇ : The discharge amount after 30 minutes from the start of discharge is reduced by 10% or more compared to the time when discharge started.
• the adhesive compositions of Examples 1 to 17 all showed a small degree of thickening with long-term heating, and had good hot melt coatability.
• the adhesive tapes in which the adhesive layers were formed from the adhesive compositions of Examples 1 to 17 had relatively high adhesive strength, and the peel distance in the constant-load peel test was relatively small, and had good adhesive strength.
• the adhesive compositions of Comparative Examples 1 and 2 showed a large viscosity increase with heating, and had poor hot melt coatability. In Comparative Examples 1 and 2, the adhesive compositions were difficult to manufacture due to the viscosity increase of the adhesive composition, and therefore the adhesive strength and constant-load peel could not be evaluated.
• the adhesive tapes in which the adhesive layers were formed from the adhesive compositions of Comparative Examples 3 and 4 had a relatively low adhesive strength, and the peel distance in the constant-load peel test was relatively large.

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