JP2019038965A - adhesive - Google Patents

Abstract

To provide an adhesive having good peelability after adhesion even though it does not substantially contain any additive for imparting the peelability thereto.SOLUTION: An adhesive containing a crystalline olefin polymer is disclosed. The olefin polymer contains as a monomer unit one or more kinds of olefin selected from the group consisting of ethylene and a 3-20C α-olefin. In the range of -50°C to 200°C in DSC thermogram as obtained by a differential scanning calorimetry of the crystalline olefin polymer, (a1) a peak generated by melting of the crystal which has a peak top in the range of 95 to 145°C is observed and (a2) a glass transition point is not observed or a glass transition point is observed in the range of -20 to 30°C.SELECTED DRAWING: None

Description

  The present invention relates to an adhesive.

  Hot melt adhesives have attracted attention as solventless type adhesives that do not generate volatile organic compounds (VOC). Hot melt adhesives are widely used in fields such as bookbinding, packaging, plywood, electronic parts, building materials, and sanitary products.

  A polymer called a base polymer is used for the hot melt adhesive. Base polymers include ethylene / vinyl acetate copolymer (Ethylene Vinyl Acetate Copolymer: EVA copolymer), ethylene / α-olefin copolymers such as ethylene-based copolymer, amorphous polyolefin (Amorphous Poly) -α-Olefin: APAO), styrene elastomers (for example, SBS, SIS, SEBS, SEPS, etc.) are known (for example, Patent Document 1 and Patent Document 2).

  For hot melt adhesives, peelability after bonding may be required. For example, an adhesive for bonding a sheet that covers a surface on which various information (information that requires confidentiality, confidentiality, and blocking properties of personal information and print information) is easily peeled off after bonding We need to be able to do it. As an example of such an application, a confidential postcard (a postcard imparted with confidentiality) that is folded with the information recording surface of a sheet on which various information is recorded inside and temporarily fixed with an adhesive is well known. In applications such as confidential postcards, the postcard is opened and information is obtained from the information recording surface. From the standpoint of ease of use of the postcard of the opener, peelability after bonding of the adhesive is important. .

  As a means for imparting peelability after bonding to a hot melt adhesive, a method of adding an additive such as wax or oil to a base polymer is known.

  For example, Patent Document 3 includes at least one selected from component (A): an olefin resin and at least one selected from waxes having a softening point of 80 to 170 ° C. (B). A hot melt type cold seal adhesive is proposed. Patent Document 4 discloses a hot melt adhesive composition used for pseudo-adhesion, which includes a thermoplastic resin containing an ethylene / propylene copolymer and solid paraffin, and the solid paraffin is There has been proposed a hot melt adhesive that is contained in an amount of 1 to 20 parts by weight with respect to 100 parts by weight of a thermoplastic resin, and the melt viscosity of the hot melt adhesive composition is 2000 to 10,000 mPa · s at 160 ° C.

International Publication No. 2015/056787 Patent No. 4053993 JP 2002-241723 A Japanese Patent Laying-Open No. 2015-145475

  However, the use of additives for imparting peelability, such as waxes and oils, can reduce the thermal stability of hot melt adhesives. The low thermal stability can contribute to poor appearance such as burning during processing.

  Therefore, an object of the present invention is to provide an adhesive that can have good peelability after bonding without substantially containing an additive for imparting peelability.

One aspect of the present invention provides an adhesive comprising a crystalline olefin polymer. The olefin polymer contains one or more olefins selected from the group consisting of ethylene and an α-olefin having 3 to 20 carbon atoms as a monomer unit. In the range of −50 ° C. to 200 ° C. of DSC thermogram obtained by differential scanning calorimetry of the crystalline olefin polymer,
(A1) A peak due to melting of the crystal having a peak top in the range of 95 to 145 ° C. is observed, and
(A2) No glass transition point is observed, or a glass transition point is observed in the range of -20 to 30 ° C.

  Even if the said adhesive agent does not contain the additive for providing peelability like wax and oil, it can have the favorable peelability after adhesion | attachment.

  The crystalline olefin polymer has a peak top in the range of 120 to 140 ° C. in the range of −50 ° C. to 200 ° C. of the DSC thermogram obtained by differential scanning calorimetry. It may be a thing.

  The crystalline olefin polymer may have a weight average molecular weight of 5 to 1,000,000, or 5 to 300,000. The crystalline olefin polymer may have a molecular weight distribution of 1 to 3.

  The crystalline olefin polymer may contain propylene as a monomer unit.

  The adhesive may be a hot melt adhesive.

  ADVANTAGE OF THE INVENTION According to this invention, even if it does not contain additives, such as wax and oil, the adhesive agent which has the favorable peelability after adhesion | attachment can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

  The adhesive according to this embodiment includes a crystalline olefin polymer composed of a specific olefin. Specifically, the crystalline olefin polymer includes one or more olefins selected from the group consisting of ethylene and an α-olefin having 3 to 20 carbon atoms as a monomer unit. In the DSC thermogram obtained by differential scanning calorimetry of this crystalline olefin polymer, in the range from −50 ° C. to 200 ° C., (a1) a peak due to melting of the crystal having a peak top in the range of 95 to 145 ° C. And (a2) a glass transition point is not observed or a glass transition point is observed in the range of -20 to 30 ° C. In the present specification, the “crystalline olefin polymer” means a crystalline olefin polymer that satisfies these requirements unless otherwise specified. Details of differential scanning calorimetry for confirming the peak due to melting of the crystal of requirement (a1) and the glass transition point of requirement (a2) will be described later.

  The crystalline olefin polymer is a polymer formed by polymerizing one or more olefins selected from the group consisting of ethylene and an α-olefin having 3 to 20 carbon atoms. The number of carbon atoms of the α-olefin constituting the crystalline olefin polymer is preferably 3 to 10 from the viewpoint of availability, cost, copolymerizability, and the like. Examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1- Hexadecene, 1-octadecene and 1-icocene are mentioned. Among these, propylene, 1-butene, 1-hexene, 1-octene and 1-decene are preferable. You may use the said olefin individually by 1 type or in mixture of 2 or more types.

  The crystalline olefin polymer is preferably a homopolymer or copolymer containing propylene as a monomer unit. Hereinafter, a crystalline olefin polymer containing propylene as a monomer unit is also referred to as a crystalline propylene polymer.

  The crystalline propylene polymer may be a copolymer including a monomer unit derived from propylene and a monomer unit derived from ethylene and / or a monomer unit derived from an α-olefin having 4 to 20 carbon atoms. .

  The proportion of monomer units derived from propylene in the crystalline propylene polymer was 85 mol% or more, 90 mol% or more, or 92 mol% or more based on the total amount of monomer units constituting the crystalline propylene polymer. It may be 100 mol% or less. The proportion of the monomer units derived from propylene is, for example, 85 to 100 mol%, 90 to 100 mol%, or 92 to 100 mol% based on the total amount of monomer units constituting the crystalline propylene polymer. Good.

  When the crystalline propylene polymer is a copolymer of propylene and another monomer such as ethylene, the melting point and glass transition point of the crystalline propylene polymer can be controlled by the type and ratio of the other monomer. it can. Usually, when the ratio of other monomers such as ethylene increases, the melting point and glass transition point of the crystalline propylene polymer tend to decrease.

  When the crystalline propylene polymer contains monomer units derived from other monomers such as ethylene and an α-olefin having 4 to 20 carbon atoms, the ratio is based on the total amount of monomer units constituting the crystalline propylene polymer. 15 mol% or less, 10 mol% or less, or 8 mol% or less. The proportion of monomer units derived from other monomers such as ethylene and α-olefin having 4 to 20 carbon atoms is, for example, 0 to 15 mol% based on the total amount of monomer units constituting the crystalline propylene polymer. It may be 0-10 mol%, or 0-8 mol%.

The ratio of each monomer component in the polymer can be determined by, for example, ¹³ C-NMR method.

  Whether the olefin polymer is crystalline can be confirmed from the presence or absence of an endothermic peak due to crystal melting in a DSC thermogram obtained by differential scanning calorimetry. In the present specification, an olefin polymer exhibiting an endothermic peak with a calorific value of 1 J / g or more due to melting of crystals is considered crystalline.

  Here, the endothermic peak due to melting of the olefin polymer crystals was heated from room temperature (usually 20-30 ° C.) to 200 ° C. at a rate of 10 ° C./min, and then immediately increased to −50 ° C. at a rate of 10 ° C./min. -50 of 2nd heating in a DSC thermogram obtained by differential scanning calorimetry including 1st heating at a temperature of 1 second heating and 2nd heating at a rate of 10 ° C / min from -50 ° C to 200 ° C. This is confirmed in the temperature rising process from ℃ to 200 ℃. The glass transition point of the olefin polymer is also confirmed in the DSC thermogram of the temperature rising process from −50 ° C. to 200 ° C. of 2nd heating obtained by differential scanning calorimetry under the same conditions.

  In the case of the crystalline olefin polymer according to one embodiment, in the above-mentioned 2nd heating DSC thermogram, an endothermic peak due to melting of the crystal having a peak top in the range of 95 to 145 ° C. is observed (requirement ( a1)). The endothermic peak here is a peak having a calorific value of 1 J / g or more. In other words, the melting point of the crystalline olefin polymer is in the range of 95 to 145 ° C. Thereby, the hot-melt-adhesive which has the more excellent peelability can be obtained. From the same viewpoint, the melting point of the crystalline olefin polymer is more preferably 100 ° C. or higher, 110 ° C. or higher, or 120 ° C. or higher. The melting point of the crystalline olefin polymer may be 143 ° C. or lower, or 140 ° C. or lower.

  In the above-mentioned 2nd heating DSC thermogram obtained by differential scanning calorimetry of the crystalline olefin polymer according to one embodiment, the glass transition point is not observed or the glass transition is in the range of -20 to 30 ° C. A point is observed (requirement (a2)). That is, the crystalline olefin polymer according to an embodiment does not show a glass transition point in the range of −50 to 200 ° C. or shows a glass transition point in the range of −20 to 30 ° C. The glass transition point here refers to the intersection of the extension line of the base line on the lower temperature side than the base line shift due to the glass transition and the tangent line at the inflection point accompanying the base line shift in the DSC thermogram. . The details of the glass transition point measurement method follow JISK7121. For example, by using a polymerization catalyst for forming a crystalline olefin polymer exhibiting a glass transition point, introducing a copolymerization monomer such as ethylene, or a combination thereof, the glass transition point is in the range of -20 to 30 ° C. A crystalline olefin polymer having the following can be obtained.

  When the crystalline olefin polymer has a glass transition point, the glass transition point is −20 ° C. or higher, preferably −16 ° C. or higher, and more preferably −10 ° C. or higher. The glass transition point is 30 ° C. or lower, preferably 10 ° C. or lower, more preferably 0 ° C. or lower, and particularly preferably −8 ° C. or lower. When the glass transition point is within these ranges, a hot melt adhesive having more excellent peelability can be obtained.

  The crystalline olefin polymer may have a weight average molecular weight Mw of 50,000 or more, 1,000,000 or less, 800,000 or less, 500,000 or less, or 300,000 or less. The weight average molecular weight Mw of the crystalline olefin polymer may be, for example, 5 to 1 million, 5 to 800,000, 5 to 500,000, or 5 to 300,000. The molecular weight distribution Mw / Mn of the crystalline olefin polymer is preferably 3 or less, more preferably 2.8 or less, and even more preferably 2.5 or less. The molecular weight distribution Mw / Mn of the crystalline olefin polymer is 1 or more, and may be 1.5 or more, or 1.8 or more. The molecular weight distribution Mw / Mn of the crystalline olefin polymer may be, for example, 1 to 3, 1.5 to 2.8, or 1.8 to 2.5. When the molecular weight distribution Mw / Mn of the olefin polymer is within the above range, it is possible to increase the time (open time) from application of the adhesive to the application of the adherend, making it more convenient as an adhesive. Sex is obtained.

  In the present embodiment, the weight average molecular weight Mw and the number average molecular weight Mn are values converted by a calibration curve created using standard polystyrene, which is measured by gel permeation chromatography (GPC method). Mw and Mn can be measured, for example, by the method described in the examples.

  The melt flow rate of the crystalline olefin polymer may be 5 g / 10 min or more, or 10 g / 10 min or more, and preferably 50 g / 10 from the viewpoint of easy mixing with other additive components described later. More than a minute. The melt flow rate of the crystalline olefin polymer may be 10,000 g / 10 min or less, or 1,000 g / 10 min or less, and preferably 100 g / 10 min from the viewpoint of giving the adhesive strength. It is as follows. The melt flow rate here means a melt flow rate measured under conditions of 230 ° C. and 2.16 kg load in accordance with ASTM D-1238.

  The crystalline olefin polymer is, for example, one or more olefins selected from the group consisting of ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of a polymerization catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. It can manufacture by polymerizing with. The polymerization catalyst is preferably a metallocene catalyst since the molecular weight distribution of the crystalline olefin polymer is narrow and the composition control is easier.

  The metallocene catalyst can typically be composed of the following component (A), component (B) and / or component (C).

  Component (A) is a metallocene compound having a transition metal element belonging to Group 4 of the periodic table of elements (eg, titanium, zirconium, hafnium, etc.). This metallocene compound has two specific organic groups linked via a transition metal element, one of the two organic groups is a group having a cyclopentadiene type anion skeleton, and the other is a cyclohexane. It is a group having a pentadiene type anion skeleton, or a phenoxy group optionally substituted with an alkyl group. The two specific organic groups to which the transition metal element is linked may optionally be further linked via another organic linking group (for example, alkylene, dialkylsilylene, etc.). In the metallocene compound, the transition metal element includes a number of atoms satisfying the valence or a group different from the two specific organic groups to which the transition metal element is connected (typically a hydrogen atom, a halogen atom, an alkyl group, or An alkoxy group). Here, examples of the group having a cyclopentadiene type anion skeleton include a cyclopentadienyl group, an indenyl group, and a fluorenyl group, and an alkyl group may be bonded to these groups.

  In the metallocene compound, the transition metal element may have tetravalent titanium, the two specific organic groups connected by titanium, and a chlorine atom bonded to titanium. That is, the metallocene compound may be titanium dichloride. Specific examples thereof include bis (cyclopentadienyl) titanium dichloride, bis (indenyl) titanium dichloride, bis (fluorenyl) titanium dichloride, (tetramethylcyclopentadienyl) (3-tert-butyl-5-methyl-2- Phenoxy) titanium dichloride, (tetramethylcyclopentadienyl) indenyltitanium dichloride, (tetramethylcyclopentadienyl) fluorenyltitanium dichloride, methylene (cyclopentadienyl) (3,5-dimethyl-2-phenoxy) Titanium dichloride, methylene (cyclopentadienyl) (3-tert-butyl-2-phenoxy) titanium dichloride, methylene (cyclopentadienyl) (3-tert-butyl-5-methyl- -Phenoxy) titanium dichloride, methylene (tetramethylcyclopentadienyl) (3,5-dimethyl-2-phenoxy) titanium dichloride, methylene (tetramethylcyclopentadienyl) (3-tert-butyl-2-phenoxy) titanium Dichloride, methylene (tetramethylcyclopentadienyl) (3-tert-butyl-5-methyl-2-phenoxy) titanium dichloride, isopropylidene (cyclopentadienyl) (3,5-dimethyl-2-phenoxy) titanium dichloride Isopropylidene (cyclopentadienyl) (3-tert-butyl-2-phenoxy) titanium dichloride, isopropylidene (cyclopentadienyl) (3-tert-butyl-5-methyl-2-phenoxy) Titanium dichloride, isopropylidene (tetramethylcyclopentadienyl) (3,5-dimethyl-2-phenoxy) titanium dichloride, isopropylidene (tetramethylcyclopentadienyl) (3-tert-butyl-2-phenoxy) titanium dichloride Isopropylidene (tetramethylcyclopentadienyl) (3-tert-butyl-5-methyl-2-phenoxy) titanium dichloride, isopropylidene (3-tert-butyl-5-methylcyclopentadienyl) indenyl titanium dichloride Isopropylidene (3-tert-butyl-5-methylcyclopentadienyl) fluorenyltitanium dichloride, dimethylsilylene (cyclopentadienyl) (3,5-dimethyl-2-phenoxy) Si) Titanium dichloride, dimethylsilylene (cyclopentadienyl) (3-tert-butyl-2-phenoxy) titanium dichloride, dimethylsilylene (cyclopentadienyl) (3-tert-butyl-5-methyl-2-phenoxy) Titanium dichloride, dimethylsilylene (tetramethylcyclopentadienyl) (3,5-dimethyl-2-phenoxy) titanium dichloride, dimethylsilylene (tetramethylcyclopentadienyl) (3-tert-butyl-2-phenoxy) titanium dichloride Dimethylsilylene (tetramethylcyclopentadienyl) (3-tert-butyl-5-methyl-2-phenoxy) titanium dichloride, dimethylsilylene (3-tert-butyl-5-methylcyclopenta) Enyl) indenyltitanium dichloride, dimethylsilylene (3-tert-butyl-5-methylcyclopentadienyl) fluorenyltitanium dichloride, methylenebis (cyclopentadienyl) titanium dichloride, dimethylsilylenebis (cyclopentadienyl) titanium Examples include dichloride, methylenebis (indenyl) titanium dichloride, dimethylsilylenebis (indenyl) titanium dichloride, methylenebis (fluorenyl) titanium dichloride, and dimethylsilylenebis (fluorenyl) titanium dichloride.

  In these metallocene compounds, titanium may be replaced with other transition metal elements (for example, zirconium or hafnium), and dichloride may be replaced with dialkyl such as dimethyl or dialkoxide such as dimethoxide.

  Component (B) is an organoaluminum compound, preferably one or more compounds selected from the group consisting of aluminum hydrides and aluminoxanes. Hydrocarbon aluminum is an organoaluminum compound having at least one hydrocarbon group such as an alkyl group bonded to aluminum. The aluminoxane is a compound including a structure represented by “—Al (R) —O—” (R represents a hydrocarbon group), and may be cyclic or linear.

  Examples of the hydrocarbon aluminum include trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, ethylaluminum dichloride, isobutylaluminum dichloride, diethylaluminum hydride and diisobutylaluminum hydride.

  Examples of the aluminoxane include compounds in which “—Al (R) —O—”, R is a methyl group, an ethyl group, or an isobutyl group. The aluminoxane can be produced by, for example, a method in which a solution obtained by dissolving a trialkylaluminum such as triisobutylaluminum in an organic solvent is brought into contact with water, a method in which a trialkylaluminum is brought into contact with a metal salt containing crystal water, and the like. In general, a cyclic or linear aluminoxane can be obtained. A commercial product can be used for aluminoxane.

  Component (C) is a boron compound, preferably one or more compounds selected from the group consisting of borane compounds and borate compounds. Here, the borane compound is a compound having a total of three groups selected from a halogen atom, a hydrocarbon group, and a halogenated hydrocarbon group bonded to boron. The borate compound is a compound composed of a borate anion having a total of four groups selected from a halogen atom, a hydrocarbon group and a halogenated hydrocarbon group bonded to boron, and a counter cation. The counter cation is not particularly limited.

  Examples of the borane compound include tris (pentafluorophenyl) borane, tris (2,3,5,6-tetrafluorophenyl) borane, tris (2,3,4,5-tetrafluorophenyl) borane, and tris (3 , 4,5-trifluorophenyl) borane, tris (2,3,4-trifluorophenyl) borane and phenylbis (pentafluorophenyl) borane.

  Examples of the borate compound include triphenylmethyltetrakis (pentafluorophenyl) borate, triethylammonium tetrakis (pentafluorophenyl) borate, tripropylammonium tetrakis (pentafluorophenyl) borate, tri (n-butyl) ammonium tetrakis (pentafluoro). Phenyl) borate, tri (n-butyl) ammonium tetrakis (3,5-bistrifluoromethylphenyl) borate, N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate and N, N-diethylanilinium tetrakis (pentafluoro) Phenyl) borate.

  The metallocene catalyst may be, for example, a catalyst described in JP-A-2000-198820, in addition to the catalyst composed of the above-described component (A) and component (B) and / or component (C). Good.

  The polymerization may be solution polymerization, suspension polymerization or the like. The polymerization method may be continuous or batchwise. The polymerization conditions may be appropriately selected from the range of polymerization conditions described in, for example, JP-A-7-48485.

  The content of the crystalline olefin polymer in the adhesive may be 20 to 100% by weight or 40 to 100% by weight based on the total weight of the adhesive. The adhesive according to the present embodiment may include other polymers in addition to the crystalline olefin polymer that satisfies the above requirements (a1) and (a2). However, the content of the other polymer is preferably 80% by weight or less or 60% by weight or less based on the total weight of the adhesive.

  The adhesive according to the present embodiment may further contain an additive for imparting releasability such as wax and oil (hereinafter referred to as “peelability imparting agent”), but substantially contains it. It does not have to be. In the present specification, “substantially containing no peelability-imparting agent” means that the content of the peelability-imparting agent is less than the effective amount required to impart peelability to the adhesive. Say. Specifically, the content of the peelability-imparting agent may be less than 50% by weight, less than 40% by weight, or 0% by weight based on the total weight of the adhesive.

  Examples of the wax include animal-derived wax, plant-derived wax, carnauba wax, candelilla wax, wood wax, beeswax, mineral wax, petroleum wax, paraffin wax, microcrystalline wax, petrolatum, polyethylene wax, polyethylene oxide wax, polypropylene wax. , Oxidized polypropylene wax, higher fatty acid wax, higher fatty acid ester wax, and Fischer-Tropsch wax.

  The adhesive according to this embodiment may further include an additive other than the peelability-imparting agent. Examples of the additive include an antioxidant, an ultraviolet absorber, a flame retardant, a fungicide, a pigment, and a dye. The content of these additives is preferably 0.01 to 10% by weight, more preferably 0.01 to 5% by weight, based on the total weight of the adhesive.

  The adhesive according to the present embodiment can be suitably used as various adhesives such as a hot melt adhesive, a laminate adhesive, and an undercoat paint (primer).

  The adhesive according to the present embodiment is produced, for example, by a method including melt-kneading a mixture containing an amorphous olefin polymer, the crystalline olefin polymer, and, if necessary, other components. be able to.

  The shape of the adhesive is not particularly limited, and may be, for example, a sheet shape, a tape shape, or a rod shape.

  When the adhesive according to this embodiment is used as a hot melt adhesive, for example, the hot melt adhesive melted by heating is attached to the first adherend and the hot melt adhesive is sandwiched between the first and second hot melt adhesives. A method comprising: bonding one adherend and a second adherend; and cooling and solidifying a hot melt adhesive between the first adherend and the second adherend, It can be used to bond the first adherend and the second adherend.

  Hereinafter, the present invention will be specifically described with reference to examples. Note that the present invention is not limited to these examples.

1. Evaluation method (melting point Tm and glass transition point Tg)
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., product name “DSC220C”), differential scanning calorimetry was performed to raise and lower the temperature at a rate of 10 ° C./min. The differential scanning calorimetry was performed under conditions including 1st heating in which the temperature was raised from room temperature to 200 ° C. and then immediately lowered to −50 ° C., and then 2nd heating in which the temperature was raised from −50 ° C. to 200 ° C. After 2nd heating, the sample was cooled to -50 ° C. The temperature at the peak top of the endothermic peak based on the melting of the crystal observed in the 2nd heating DSC thermogram was defined as the melting point Tm of the crystalline olefin polymer. In addition, the temperature at the inflection point of the baseline shift showing the specific heat change accompanying the glass transition behavior of the crystalline olefin polymer in the 2nd heating DSC thermogram was determined as the glass transition point Tg.

(Molecular weight, molecular weight distribution)
The molecular weight was measured by gel permeation chromatography (GPC method) using a GPC apparatus (product name “150C / GPC apparatus” manufactured by Waters). As the column, “Shodex Packed Column A-80M” manufactured by Showa Denko KK was used. Standard polystyrene manufactured by Tosoh Corporation was used as the molecular weight standard substance.
About 5 mg of a crystalline olefin polymer was dissolved in 5 mL of o-dichlorobenzene to prepare a solution having a concentration of about 1 g / L. 400 μL of the adjusted sample solution was injected into the column, and measurement was carried out under conditions of an elution temperature of 140 ° C. and an elution solvent flow rate of 1.0 mL / min, and detected by a refractive index detector. From the obtained weight average molecular weight Mw (polystyrene conversion) and number average molecular weight Mn (polystyrene conversion), the ratio Mw / Mn of the two was determined, and this was used as the molecular weight distribution.

(Evaluation of peelability)
The sheet-like hot melt adhesives produced in the examples and comparative examples were cut into strips of about 0.15 g and placed on cardboard pieces. The hot melt adhesive on the cardboard piece was heated by a heat source at 230 ° C. from a distance of about 1 mm for 10 minutes. Immediately after releasing the heat source, another cardboard piece was placed on the hot melt adhesive, and a weight of 1 kg was placed thereon, and the cardboard pieces were adhered to each other by the hot melt adhesive by allowing to stand for 1 hour. An adhesive body was produced. The cardboard pieces of the adhesive were peeled off by hand. The state of peeling was observed and peelability was evaluated according to the following criteria.
○: Interfacial peeling (peeling at the adhesive interface between the corrugated cardboard piece and the hot melt adhesive)
Δ: Less than 30% of the boundary area between the corrugated board piece and the adhesive layer was damaged on the corrugated board side.
X: 30% or more of the boundary area between the corrugated board piece and the adhesive layer was damaged on the corrugated board piece side.

(Evaluation of thermal weight loss)
The crystalline olefin polymer was heated for 30 minutes at 240 ° C. in a nitrogen atmosphere using a differential thermothermal gravimetric simultaneous measurement apparatus (manufactured by Hitachi High-Tech Science Co., Ltd., model “TG / DTA6200”). The weight at that time (polymer weight after heating for 30 minutes) was used as a reference. Under the same conditions, the weight at the time when heating was continued for 90 minutes (polymer weight after heating for 120 minutes) was measured, and the weight loss% was calculated from the following formula.
Weight loss% = {[(polymer weight after heating for 30 minutes) − (polymer weight after heating for 120 minutes)] / (polymer weight after heating for 30 minutes)} × 100%

2. Preparation and evaluation of hot melt adhesive [Example 1]
125 g of dry toluene was charged into a 0.4 L polymerization apparatus purged with nitrogen, and 40 g of propylene was charged. The internal temperature of the polymerization apparatus was raised to 70 ° C., 4693 mmol / L of triisobutylaluminum (TiBA), 0.2 μmol / L of dimethylsilylene bisindenylzirconium dichloride (SIZC), and dimethylanilinium tetrakis (pentafluorophenyl) borate. Polymerization was started by adding 3.3 mol / L. After continuing the polymerization for 180 minutes, 5 mL of ethanol was added to terminate the polymerization. After depressurization, the product was precipitated from the polymerization solution in 10 L of acetone, and the precipitate was vacuum-dried to obtain the desired crystalline olefin polymer. The crystalline olefin polymer (propylene homopolymer) obtained was measured for melting point Tm, glass transition point Tg, weight average molecular weight Mw, and molecular weight distribution Mw / Mn.
The crystalline olefin polymer was processed with a press to produce a sheet-like hot melt adhesive, and the peelability was evaluated using this. The results are shown in Table 1.

[Example 2]
Using dimethylsilylene bisindenyl hafnium dichloride (SIHC) instead of SIZC as the metallocene compound, the target crystalline olefin polymer (propylene homopolymer) was prepared in the same manner as in Example 1 under the conditions shown in Table 1. Obtained. The melting point Tm, glass transition point Tg, weight average molecular weight Mw, and molecular weight distribution Mw / Mn of the obtained crystalline olefin polymer were measured. A sheet-like hot melt adhesive was prepared using a crystalline olefin polymer, and its peelability was evaluated. The results are shown in Table 1.

[Examples 3 to 4]
Propylene and ethylene are used as monomers, SIHC is used as the metallocene compound, and the crystalline olefin polymers (ethylene / propylene copolymers) of Examples 3 and 4 are prepared in the same manner as in Example 1 under the conditions described in Table 1. Obtained. The melting point Tm, glass transition point Tg, weight average molecular weight Mw, and molecular weight distribution Mw / Mn of the obtained crystalline olefin polymer were measured. A sheet-like hot melt adhesive was prepared using a crystalline olefin polymer, and its peelability was evaluated. The results are shown in Table 1.

[Comparative Example 1]
As the polymer, lycocene (manufactured by Clariant, product name “PP2602”) was used as it was. The melting point Tm, the glass transition point Tg, the weight average molecular weight Mw, and the molecular weight distribution Mw / Mn of the polymer were measured. A sheet-like hot melt adhesive was prepared using this polymer, and its peelability was evaluated. The results are shown in Table 1.

[Comparative Examples 2 to 4]
Propylene and ethylene were used as monomers, and crystalline olefin polymers (ethylene / propylene copolymers) of Comparative Examples 2 to 4 were obtained under the conditions shown in Table 1. The melting point Tm, glass transition point Tg, weight average molecular weight Mw, and molecular weight distribution Mw / Mn of the obtained crystalline olefin polymer were measured. A sheet-like hot melt adhesive was prepared using a crystalline olefin polymer, and its peelability was evaluated. The results are shown in Table 1.

Claims (7)

An adhesive comprising a crystalline olefin polymer,
The crystalline olefin polymer contains, as a monomer unit, one or more olefins selected from the group consisting of ethylene and an α-olefin having 3 to 20 carbon atoms,
In the range of −50 ° C. to 200 ° C. of DSC thermogram obtained by differential scanning calorimetry of the crystalline olefin polymer,
(A1) A peak due to melting of the crystal having a peak top in the range of 95 to 145 ° C. is observed, and
(A2) No glass transition point is observed, or a glass transition point is observed in the range of -20 to 30 ° C.
adhesive.   In the DSC thermogram obtained by differential scanning calorimetry of the crystalline olefin polymer, a peak due to crystal melting having a peak top in the range of 120 to 140 ° C. is observed in the range of −50 ° C. to 200 ° C. The adhesive according to claim 1.   The adhesive according to claim 1 or 2, wherein the crystalline olefin polymer has a weight average molecular weight of 5 to 1,000,000.   The adhesive according to claim 1 or 2, wherein the crystalline olefin polymer has a weight average molecular weight of 5 to 300,000.   The adhesive according to any one of claims 1 to 4, wherein the crystalline olefin polymer has a molecular weight distribution of 1 to 3.   The adhesive according to any one of claims 1 to 5, wherein the crystalline olefin polymer contains propylene as a monomer unit.   The adhesive according to any one of claims 1 to 6, which is a hot melt adhesive.