Hot melt adhesive, heat sensitive label and container using same

Abstract

To provide a hot melt adhesive which has a long open time, excellent blocking properties, and excellent adhesion not only to paper labels but also to plastic labels such as PET and OPP, and to provide a heat-sensitive label and a container which do not jam when using the hot melt adhesive. [Solution] A hot melt adhesive comprising an ethylene-vinyl acetate copolymer (A), a tackifier resin (B), and a saturated fatty acid triglyceride (C), wherein the ethylene-vinyl acetate copolymer (A) has a vinyl acetate content of 26% by mass or more and less than 45% by mass, the ethylene-vinyl acetate copolymer (A) has a melt mass-flow rate (MFR) of 12 to 200 g / 10 min at 190°C and 21.18 N, as measured in accordance with JIS K7210, and the saturated fatty acid triglyceride (C) has a melting point of 65 to 100°C.

Description

[Technical field]

[0001] The present invention relates to a hot melt adhesive. The present invention further relates to a heat-sensitive label using the hot melt adhesive and a container having the heat-sensitive label attached thereto. [Background technology]

[0002] Hot melt adhesives are solvent-free, making them environmentally and work-friendly. In addition, after being heated and melted, they are applied to films and paper substrates, and then cooled and hardened, allowing them to be rolled up immediately, making the coating machine compact. Furthermore, when substrates are bonded together in a heated and melted state, they immediately cool and harden, so they have many other advantages, such as functioning as an instant adhesive.

[0003] Tack labels are often used for labels on glass bottles and plastic bottles, but because the release paper (film) is generated as waste, they are not suitable for reducing waste. Therefore, heat-sensitive labels have attracted attention as tack-paper-less labels. Delayed tack (Patent Document 1) and hot melt (Patent Document 2) have been used as adhesives for heat-sensitive labels, but delayed tack has a problem in that it uses dicyclohexyl phthalate (DCHP), a suspected environmental hormone, as a solid plasticizer, and hot melt adhesives have a problem in that stable adhesion cannot be obtained due to their short open time, and there are also issues such as the adhesive adhering to the labeler's cutter during labeling, causing jamming, so they have not become widespread. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 55-16055 [Patent Document 2] JP 2000-137438 A Summary of the Invention [Problem to be solved by the invention]

[0005] Hot melt adhesives for heat-sensitive labels have the advantage of being environmentally friendly. However, as mentioned above, hot melt adhesives have a short open time and the adhesiveness during labeling is not stable. Furthermore, while the adhesiveness of hot melt adhesives is good for paper labels, the adhesiveness of plastic labels such as polyethylene terephthalate (PET) and biaxially oriented polypropylene (OPP) is weak.

[0006] An object of the present invention is to provide a hot melt adhesive that has a long open time and excellent blocking properties, and that provides good adhesion not only to paper labels but also to plastic labels such as PET and OPP, and to provide a heat-sensitive label and container that use this hot melt adhesive and do not jam. [Means for solving the problem]

[0007] The present disclosure relates to the following hot melt adhesive, heat-sensitive label, and container to which the same is affixed. [1] A hot melt adhesive comprising an ethylene-vinyl acetate copolymer (A), a tackifier resin (B), and a saturated fatty acid triglyceride (C), wherein the ethylene-vinyl acetate copolymer (A) has a vinyl acetate content of 26% by mass or more and less than 45% by mass, the ethylene-vinyl acetate copolymer (A) has a melt mass-flow rate (MFR) of 12 to 200 g / 10 min at 190°C and 21.18 N, as measured in accordance with JIS K7210, and the saturated fatty acid triglyceride (C) has a melting point of 65 to 100°C.

[0008] [2] The hot melt adhesive as described above, wherein the tackifier resin (B) has a softening point of 80 to 120°C.

[0009] [3] The hot melt adhesive, characterized in that the content of ethylene-vinyl acetate copolymer (A) is 10 to 70 mass%, the content of tackifier resin (B) is 10 to 70 mass%, and the content of saturated fatty acid triglyceride (C) is 5 to 70 mass%, relative to 100 mass% in total of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), and the saturated fatty acid triglyceride (C).

[0010] [4] A heat-sensitive label having an adhesive layer made of the above hot melt adhesive.

[0011] [5] A container with the heat-sensitive label affixed. Effect of the Invention

[0012] The present disclosure has the excellent effect of providing a hot melt adhesive that has a long open time, excellent blocking properties, and good adhesion not only to paper labels but also to plastic labels such as PET and OPP, as well as a heat-sensitive label and container that use the hot melt adhesive and do not jam. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present disclosure will be described in detail below. It should be noted that other embodiments are of course included in the scope of the present invention as long as they conform to the spirit of the present invention. In this specification, the term "hot melt" refers to a material that is in a solid or viscous state at room temperature and melts and becomes fluid or liquid when heated. In addition, in this specification, a numerical range specified by using "~" includes the numerical values ​​before and after "~" as the lower and upper limit values ​​of the range. In addition, unless otherwise noted, each of the various components appearing in this specification may be used independently, either alone or in combination of two or more types.

[0014] In this specification, the "melting point of the saturated fatty acid triglyceride (C)" can be measured by the melting point measurement method described in the Japanese Standards for Food Additives (8th edition).

[0015] The hot melt adhesive disclosed herein has a moderate open time, which allows it to achieve both stable adhesion during labeling and excellent blocking properties when solidified, and is therefore suitable for use with heat-sensitive labels and containers to which such heat-sensitive labels are affixed, but it can also be used for any application.

[0016] <Hot melt adhesive> The hot melt adhesive of the present invention contains an ethylene-vinyl acetate copolymer (A), a tackifier resin (B) and a saturated fatty acid triglyceride (C). In the hot melt composition of the present invention, it is preferable that the ethylene-vinyl acetate copolymer (A) is 10 to 70% by mass, the tackifier resin (B) is 10 to 70% by mass, and the saturated fatty acid triglyceride (C) is 5 to 70% by mass, out of a total of 100% by mass of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), and the saturated fatty acid triglyceride (C). By making the ethylene-vinyl acetate copolymer (A) 10 to 70% by mass, the adhesiveness (cohesive strength) is kept good, and more preferably 20 to 50% by mass. By making the tackifier resin (B) 10 to 70% by mass, the adhesiveness (adhesion) is kept good, and more preferably 20 to 50% by mass. By making the saturated fatty acid triglyceride (C) 5 to 70% by mass, the open time and blocking property can be kept good, and more preferably 20 to 50% by mass.

[0017] In 100% by mass of the hot melt adhesive, the total content of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B) and the saturated fatty acid triglyceride (C) is preferably 60 to 100% by mass. By setting it in this range, the adhesiveness and blocking properties can be more effectively brought out. A more suitable range is 70 to 100% by mass, and an even more suitable range is 80 to 100% by mass.

[0018] <Ethylene-vinyl acetate copolymer (A)> The ethylene-vinyl acetate copolymer (A) is an ethylene-vinyl acetate copolymer having a vinyl acetate content of 26% by mass or more and less than 45% by mass. If the vinyl acetate content is 45% by mass or more, the blocking property decreases, and if the vinyl acetate content is less than 26% by mass, the adhesive property decreases. The upper limit of the vinyl acetate content is more preferably less than 35% by mass.

[0019] The melt mass flow rate (MFR) of the ethylene-vinyl acetate copolymer (A) is 12 to 200 g / 10 min. From the viewpoint of blocking resistance and adhesiveness, it is preferably 100 to 200 g / 10 min. The MFR is a value measured in accordance with JIS K7210.

[0020] <Tackifying resin (B)> The tackifier resin (B) constituting the hot melt adhesive of the present invention is not particularly limited, and examples thereof include phenolic resins, modified phenolic resins, terpene phenolic resins, xylene phenolic resins, cyclopentadiene-phenolic resins, xylene resins, aliphatic, alicyclic, aromatic petroleum resins, hydrogenated aliphatic, alicyclic, aromatic petroleum resins, phenol-modified petroleum resins, rosin ester resins, hydrogenated rosin, acid-modified rosin, hydrogenated rosin ester resins, low molecular weight polystyrene resins, terpene resins, and hydrogenated terpene resins. From the viewpoint of adhesion and blocking properties, preferred are rosin-based tackifier resins such as rosin ester resin, hydrogenated rosin, acid-modified rosin, hydrogenated rosin ester resin, etc. Among these, acid-modified rosin is preferred, and maleic acid-modified rosin is particularly preferred.

[0021] The softening point of the tackifier resin is preferably from 80 to 120° C., and more preferably from 90 to 110° C., from the viewpoints of adhesiveness and blocking properties. The method for measuring the softening point will be described in the Examples. The acid value of the tackifier resin is not particularly limited, but when the material of the container to which the heat-sensitive label is attached is a bottle, metal, etc., the acid value of the tackifier resin is preferably 20 to 300 mgKOH / g. The larger the acid value, the better the results will be, as the label will not peel off when condensation occurs when it is attached to a highly polar container such as a bottle or metal.

[0022] <Saturated fatty acid triglyceride (C)> Generally, saturated fatty acid triglyceride refers to fats and oils that are liquid at room temperature because they contain a large amount of unsaturated fatty acid triglycerides with a relatively low melting point, and are hydrogenated to increase the proportion of saturated fatty acid triglycerides with a higher melting point, resulting in a solidified fat and oil at room temperature. Representative fats and oils include palm oil, olive oil, rapeseed oil, sesame oil, cottonseed oil, soybean oil, sunflower oil, safflower oil, rice bran oil, corn oil, coconut oil, linseed oil, beef tallow, lard, and fish oil, and their hydrogenated oils (hydrogenated products) are examples of saturated fatty acid triglycerides (C) in the present invention. From the viewpoint of blocking properties and adhesive properties, rapeseed hydrogenated oil is preferred.

[0023] The fats and oils before hardening are composed of a mixture of fatty acid triglycerides having 6 to 22 carbon atoms, and are hardened by hydrogenation to increase the melting point. The melting point of the saturated fatty acid triglyceride (C) used in the present invention is 65 to 100°C. In terms of blocking property and open time, it is preferably 65 to 80°C. When the melting point of the saturated fatty acid triglyceride (C) is 65 to 100°C, good blocking property and long open time performance can be obtained.

[0024] The saturated fatty acid in the saturated fatty acid triglyceride (C) is preferably one that does not have a hydroxyl group. If a hydroxyl group is present, the open time will be longer, but the blocking property may be deteriorated.

[0025] <Other ingredients> The hot melt adhesive of the present invention may further contain other components within a range that does not impair the effects of the present invention. Examples of other components include ethylene-vinyl acetate copolymers (XA) other than ethylene-vinyl acetate copolymers (A) having a vinyl acetate content of 26% by mass or more and less than 45% by mass, wax, colorants, antiblocking agents, inorganic fillers, antioxidants, bulking agents, flame retardants, plasticizers, antistatic agents, light stabilizers, ultraviolet absorbers, heavy metal deactivators, etc. These components may be used alone or in combination of two or more.

[0026] The ethylene-vinyl acetate copolymer (XA) other than (A) is an ethylene-vinyl acetate copolymer having a vinyl acetate content of less than 26% by mass, or an ethylene-vinyl acetate copolymer having a vinyl acetate content of 45% by mass or more, or an ethylene-vinyl acetate copolymer having a vinyl acetate content of 26% by mass or more but less than 45% by mass and a melt mass flow rate (MFR) of less than 12 g / 10 min or more than 200 g / 10 min at 190 ° C. and 21.18 N measured in accordance with JIS K7210. The content of the ethylene-vinyl acetate copolymer (XA) is preferably 50% by mass or less, more preferably 30% by mass or less, relative to the ethylene-vinyl acetate copolymer (A). By making the content of (XA) relative to (A) 50% by mass or less, adhesion to plastic labels such as OPP and PET labels can be ensured.

[0027] The wax plays a role in improving the blocking property of the hot melt adhesive. Examples of the wax include carnauba wax, candelilla wax, montan wax, paraffin wax, micro wax, Fischer-Tropsch wax, polyethylene wax, polypropylene wax, and oxides of these waxes. Other examples include ethylene-acrylic acid copolymer wax, ethylene-methacrylic acid copolymer wax, and the like.

[0028] The colorant may be a commonly used colorant such as red, blue, green, yellow, etc. The colorant may be any of pigments, dyes, and colorants, and examples of the colorant include monoazo, dizazo, azo lake, benzimidazolone, perylene, diketopyrrolopyrrole, condensed azo, anthraquinone, quinacridone, phthalocyanine, and anthraquinone, and examples of the pigment include pigment, perylene, monoazo, condensed azo, isoindolinone, titanium oxide, and carbon.

[0029] The blocking inhibitor may, for example, be silicone, unsaturated fatty acid amides such as stearic acid amide, oleic acid amide, erucic acid amide, oleic acid amide, and behenic acid amide.

[0030] Examples of the inorganic filler include particles and fibers of metals, metal oxides, metal hydroxides, etc. Specific examples include glass fibers, carbon fibers, calcium silicate, calcium titanate, aluminum borate fibers, flake glass, talc, kaolin, mica, hydrotalcite, calcium carbonate, zinc carbonate, zinc oxide, calcium hydrogen phosphate, wollastonite, silica, zeolite, alumina, boehmite, aluminum hydroxide, titanium oxide, silicon oxide, magnesium oxide, calcium silicate, alumina sodium silicate, magnesium silicate, carbon nanotube, graphite, copper, silver, aluminum, nickel, iron, calcium fluoride, mica, montmorillonite, apatite, etc.

[0031] The antioxidants include high molecular weight hindered polyhydric phenols, triazine derivatives, high molecular weight hindered phenols, dialkyl phenol sulfides, 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol, 4,4'-methylene-bis-(2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, 2,2, Examples include 4-trimethyl-1,2-dihydroquinoline, 2,2,4-trimethyl-1,2-dihydroquinoline polymers, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, dibutyl dithiocarbamate nickel, 1-oxy-3-methyl-4-isopropylbenzene, 4,4'-butylidenebis-(3-methyl-6-tert-butylphenol), and 2-mercaptobenzimidazole. Antioxidants can be used to prevent thermal degradation and decomposition.

[0032] Examples of the filler include wet silica, aluminum hydroxide, aluminum oxide, magnesium oxide, montmorillonite, mica, smectite, organically modified montmorillonite, organically modified mica, and organically modified smectite.

[0033] Examples of the flame retardant include phosphorus-containing compound-based flame retardants, halogen-containing compound-based flame retardants, sulfonic acid metal salt-based flame retardants, and silicon-containing compound-based flame retardants.

[0034] Examples of the plasticizer include phthalate ester plasticizers, polyester plasticizers, aliphatic dibasic acid ester plasticizers, aliphatic monobasic acid ester plasticizers, phosphate ester plasticizers, citrate ester plasticizers, epoxy plasticizers, trimellitate ester plasticizers, tetrahydrophthalate ester plasticizers, glycol plasticizers, and bisphenol A alkylene oxide derivatives.

[0035] The antistatic agent may be any agent commonly used as an antistatic agent for plastics, and specific examples thereof include nonionic surfactants (e.g., fatty acid esters of polyhydric alcohols, ethylene oxide adducts of alkylamines, and fatty acid esters of ethylene oxide adducts of alkylamines), anionic surfactants (e.g., alkylbenzenesulfonates, higher alcohol sulfate salts), cationic surfactants (e.g., aliphatic amine salts, quaternary ammonium salts), and amphoteric surfactants (e.g., imidazoline type, betaine type, etc.).

[0036] Examples of the light stabilizer include hindered amine compounds and benzoate compounds.

[0037] Examples of the ultraviolet absorbing agent include a benzophenone-based ultraviolet absorbing agent, a triazine-based ultraviolet absorbing agent, and a benzotriazole-based ultraviolet absorbing agent.

[0038] The heavy metal deactivator includes a salicylic acid derivative, a hydrazide derivative, an oxalic acid amide derivative, and the like.

[0039] <Manufacturing of hot melt adhesives> The hot melt adhesive of the present invention can be produced, for example, by adding the ethylene-vinyl acetate copolymer (A) and the tackifier resin (B) to a mixture of the saturated fatty acid triglyceride (C) melted in a melting kettle equipped with a stirrer, and mixing them. The hot melt adhesive of the present invention may also be produced by mixing and dispersing the blended components in an extruder, and extruding the molten mixture from a nozzle at the tip of the extruder.

[0040] The hot melt adhesive of the present invention may be used by mixing the compounding components and molding them into a desired shape. Examples of the desired shape include granular, pellet, sheet, and block shapes. These methods can be performed using known methods without any restrictions.

[0041] <Thermal label> The heat-sensitive label of the present invention has an adhesive layer made of the above-mentioned hot melt adhesive. The adhesive layer may be provided on the label substrate, or an intermediate layer such as an ink layer may be provided between the label substrate and the hot melt adhesive.

[0042] Label substrates include paper, plastic, synthetic paper, etc. Plastics include PET, OPP, PVC, polyethylene, etc.

[0043] The heat-sensitive label can be produced by a known method, for example, by applying a hot melt adhesive to a label substrate and cooling it. An example of a method for applying a hot melt adhesive to a label substrate is to heat the adhesive to make it liquid, and then form a layer using a coater. Examples of coaters include blade coaters, bar coaters, comma coaters, gravure coaters, roll coaters, reverse roll coaters, die coaters, and T-die coating. After application, an organic solvent may be added to adjust the viscosity by cooling. When an organic solvent is used, the organic solvent may be removed using a hot air drying oven.

[0044] In the heat-sensitive label of the present invention, the coating amount of the adhesive is 7 to 20 g / m from the viewpoints of adhesion and jamming prevention. 2 is preferable. 2 is more preferred. The coating may be a full surface coating, or a partial coating such as a line, lattice, wave, or dot coating, or a combination of these.

[0045] <Containers with heat-sensitive labels> The containers to which the heat-sensitive label of the present invention is attached include glass, ceramic, plastic, or metal containers. The heat-sensitive label can be attached by heating the label and attaching it to the bottle, or by setting the label in a mold beforehand when in-mold molding plastic containers, etc., and adhering the label to the container by utilizing the heat generated when molding the container. The heat-sensitive label may be wrapped around the container all the way around. The glass bottle, which is one of the containers of the present invention, may be a transparent bottle, a brown bottle, or a colored bottle such as blue, red, or green. The surface of the glass bottle may be untreated or coated with a resin such as cold coating, hot coating, or polyethylene (PE) coating. The heat-sensitive label of the present invention can be applied to glass products other than glass bottles, metal products such as metal containers, and other materials.

[0046] As the plastics which are one of the containers of the present invention, any material that can be used as a single container, such as olefins such as high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and polypropylene, polystyrene, polyester (PET, etc.), polycarbonate, and vinyl chloride, can be used. In addition, when a multi-layer structure is possible, a foam layer can be placed on one side of the container and the same resin can be extruded without foaming to make a multi-layer container, for the purpose of improving the impact resistance of the container. In-mold molding methods include vacuum molding, compressed air molding, extrusion blow molding, injection molding, injection blow molding, and biaxial stretch blow molding.

[0047] In vacuum forming, compressed air forming, extrusion blow molding, injection molding, injection blow molding, biaxial stretch blow molding, etc., when attaching a label to the outer surface of a resin container, typically a polyolefin container or a polyethylene terephthalate container, an in-mold label method is known in which an in-mold label is arranged in advance on the cavity surface of a mold for molding, and the in-mold label is attached to the outer surface of the container by heat fusion at the same time as the container is molded. This in-mold label method has the advantage that the in-mold label can be attached to the entire outer surface of the container, so that the label is not easily peeled off from the container and large-area labeling is easy. In addition, it is possible to increase the rigidity of the container, and the container can be made thin, which has excellent design properties, and has the advantages of reducing manpower and space in the process, and is therefore preferably used.

[0048] With these application methods, a heat-sensitive label having a hot melt adhesive layer (not sticky at room temperature) is applied to an adherend while being heated, eliminating the need for release paper, preventing contamination of the application machine, making it easy to align the labeling, and enabling application without blocking during normal transportation and handling. No release paper is required, which reduces waste, making these labels environmentally friendly.

[0049] By using the hot melt adhesive of the present invention, it is possible to remarkably improve the performance of heat-sensitive labels, which have a long open time and good blocking properties. The reason for this is that when the heat-sensitive label is adhered to a substrate after heating, the hot melt adhesive has a long open time, so that the hot melt adhesive can be easily adhered to the substrate even if the heat of the hot melt adhesive is absorbed by the substrate. EXAMPLES

[0050] Next, the present invention will be described based on specific examples in comparison with comparative examples, but the present invention is not limited to these. In the examples, "parts" and "%" respectively represent "parts by mass" and "% by mass" unless otherwise specified.

[0051] [Measurement of Melt Mass Flow Rate (MFR) of Ethylene-Vinyl Acetate Copolymer (A)] The MFR of the ethylene-vinyl acetate copolymer (A) was measured in accordance with JIS K 7210. Specifically, the resin placed in a cylindrical extrusion-type plastometer was heated and pressurized (21.18 N) at 190°C, and the amount of resin extruded from the bottom opening of the container in 10 minutes was measured.

[0052] [Melt point measurement of saturated fatty acid triglyceride (C)] The melting point of the saturated fatty acid triglyceride (C) was measured by the melting point measurement method described in the Food Additives Standards (8th edition). Specifically, dried powdered saturated fatty acid triglyceride was placed in a capillary tube, tightly packed, and then heated to about 100°C. The melting point was determined as the temperature at which the saturated fatty acid triglyceride completely melted and became transparent.

[0053] [Measurement of softening point of tackifier resin (B)] The softening point of the tackifier resin (B) was measured according to JIS K 6863. Specifically, after filling a ring base with the tackifier resin (B), a ball (specified in JIS B1501: steel ball / diameter 9.53 mm / mass 3.5±0.05 g) was placed on it, and the temperature at which the ball dropped at a heating rate of 5° C. / ° C. was taken as the melting point using a bulb-type automatic softening point tester ASP-KG4 type (manufactured by Matex Co., Ltd.).

[0054] [Measurement of acid value of tackifier resin (B)] The acid value of the tackifier resin (B) is the number of milligrams of potassium hydroxide (KOH) required to neutralize 1 g of sample, and is a value measured in accordance with JIS K5601-2-1 Acid Value (Titration Method). Specifically, 1 g of sample was dissolved in 2 volumes of toluene and 1 volume of ethanol [95% (V / V)], and then titrated with phenolphthalein indicator to determine the acid value.

[0055] Ethylene-vinyl acetate copolymer (A) A-1: Ultrasen 752 (manufactured by Tosoh Corporation, ethylene-vinyl acetate copolymer, vinyl acetate content 32% by mass, MFR: 60 g / 10 min) A-2: Ultrasen 720 (manufactured by Tosoh Corporation, ethylene-vinyl acetate copolymer, vinyl acetate content 28% by mass, MFR: 150 g / 10 min) A-3: Ultrasen 760 (manufactured by Tosoh Corporation, ethylene-vinyl acetate copolymer, vinyl acetate content 42% by mass, MFR: 70 g / 10 min) A-4: Evaflex EV250 (manufactured by Dow Mitsui Polychemicals, ethylene-vinyl acetate copolymer, vinyl acetate content 28% by mass, MFR: 15g / 10min)

[0056] XA-1: Ultrathene 722 (Tosoh Corporation, ethylene-vinyl acetate copolymer, vinyl acetate content 28% by mass, MFR: 400g / 10min) XA-2: Ultrathene 633 (manufactured by Tosoh Corporation, ethylene-vinyl acetate copolymer, vinyl acetate content 20% by mass, MFR: 20g / 10min)

[0057] ·Tackifying resin (B) B-1: KE-604B (Arakawa Chemical Co., Ltd., acrylic acid modified rosin, softening point: 129°C, acid value: 246mgKOH / g) B-2: Haritac 4821 (Harima Chemicals, maleic acid modified rosin, softening point: 107°C, acid value: 22.5mgKOH / g) B-3: Alcon P-115 (Arakawa Chemical Co., Ltd., fully hydrogenated petroleum hydrocarbon, softening point: 115°C, acid value: none) B-4: Crystallex F100 (manufactured by Eastman Chemical Company, copolymer of α-methylstyrene and styrene, softening point 100°C, acid value: none) B-5: Pencel A (Arakawa Chemical Industries, rosin ester, softening point: 105°C, acid value: none) B-6: T-REZ HA85 (ENEOS, hydrogenated petroleum resin, softening point: 85°C, acid value: none) B-7:RHR-301 (manufactured by China Wuzhou Sun Shine Forestry & Chemicals Co., LTD of Guangxi, hydrogenated rosin, softening point: 75℃, acid value: 165mgKOH / g)

[0058] Saturated fatty acid triglycerides (C) C-1: Hardened rapeseed oil (manufactured by Yokoseki Oil Industries, melting point: 70°C) C-2: Castor oil (manufactured by Yokoseki Oil Industries, melting point: 85°C) C-3: Hardened soybean oil (manufactured by Yamakei Sangyo Co., Ltd., melting point: 68°C)

[0059] Other saturated fatty acid triglycerides (XC) XC-1: Hardened palm oil (manufactured by Yokoseki Oil Industries Co., Ltd., melting point: 59°C)

[0060] Additives (D) D-1: Antioxidant: IRGANOX1010 (BASF) D-2: Silicone KF96 100CS (Shin-Etsu Chemical Co., Ltd., silicone)

[0061] Example 1: Preparation of hot melt adhesive 30 parts of saturated fatty acid triglyceride (C-1), 0.1 parts of additive (D) IRGANOX1010, and 0.2 parts of silicone KF96 100CS were placed in a container, heated and melted at 150°C, and then 40 parts of ethylene-vinyl acetate copolymer (A-2) and 30 parts of tackifier resin (B-2) were gradually added while stirring with a stirrer. The ethylene-vinyl acetate copolymer was completely dissolved, and the hot melt adhesive of Example 1 was obtained.

[0062] Example 2: Preparation of hot melt adhesive 20 parts of saturated fatty acid triglyceride (C-1) and 0.1 parts of additive (D) IRGANOX1010 were placed in a container, heated and melted at 150°C, and then 15 parts of ethylene-vinyl acetate copolymer (A-1) and 65 parts of tackifier resin (B-2) were gradually added while stirring with a stirrer. The ethylene-vinyl acetate copolymer was completely dissolved, and the hot melt adhesive of Example 2 was obtained.

[0063] (Examples 3 to 13) The hot melt adhesive properties of Examples 3 to 13 were obtained in the same manner as in Example 2, except that the materials and compounding ratios shown in Table 1 were changed.

[0064] Comparative Example 1 40 parts of saturated fatty acid triglyceride (C-1) and 0.1 parts of additive (D) IRGANOX1010 were placed in a container and heated to 150°C for melting, and then 30 parts of ethylene-vinyl acetate copolymer (XA-2) and 30 parts of tackifier resin (B-2) were gradually added while stirring with a stirrer. The ethylene-vinyl acetate copolymer was completely dissolved, and the hot melt adhesive of Comparative Example 1 was obtained.

[0065] Comparative Example 2 50 parts of saturated fatty acid triglyceride (C-1) and 0.1 parts of additive (D) IRGANOX1010 were placed in a container and heated to 150°C to melt, and then 50 parts of tackifier resin (B-5) was gradually added while stirring with a stirrer to obtain the hot melt adhesive of Comparative Example 2.

[0066] Comparative Example 3 50 parts of saturated fatty acid triglyceride (C-1) and 0.1 parts of additive (D) IRGANOX1010 were placed in a container, heated and melted at 150°C, and then 50 parts of ethylene-vinyl acetate copolymer (A-2) were gradually added while stirring with a stirrer. The ethylene-vinyl acetate copolymer was completely dissolved, and the hot melt adhesive of Comparative Example 3 was obtained.

[0067] Comparative Example 4 30 parts of saturated fatty acid triglyceride (XC-1) and 0.1 parts of additive (D) IRGANOX1010 were placed in a container and heated to 150°C for melting, and then 55 parts of ethylene-vinyl acetate copolymer (XA-1) and 15 parts of tackifier resin (B-4) were gradually added while stirring with a stirrer. The ethylene-vinyl acetate copolymer was completely dissolved, and the hot melt adhesive of Comparative Example 4 was obtained.

[0068] (Thermal label manufacturing) Using a hot melt roll coater, apply a coating amount of 10 to 30 g / m using the label substrate shown below. 2 We created thermal labels of each type. Coated paper: 84.9 g / m 2 (No printing) OPP: 40μm OPP film (no corona treatment) PET: 25μm PET film (no corona treatment) Coating method: Gravure coating (HM temperature during coating: 140-150°C, cylinder temperature: 140-150°C, hopper temperature: 150-180°C)

[0069] (Evaluation of Adhesion) The adhesiveness was evaluated using non-oriented polypropylene (CPP, thickness: 500 μm) as the adherend, and the following evaluation was carried out, with the most favorable evaluation result being adopted. Using a heat sealer (TP-701-G Heat Seal Tester Thermal Gradient Type, manufactured by Tester Sangyo Co., Ltd.), the heat-sensitive label and the adherend were heat-sealed for 1 second at a heating temperature of 140°C and a pressure of 0.1 MPa, and then stored for 24 hours or more in a constant temperature and humidity room at a temperature of 23°C and a humidity of 65%. Evaluation was performed by peeling at a speed of 300 mm / min using a tensile tester, and the results were evaluated according to the following criteria. ◎: Base material destruction or 1.5N / 15mm or more: Excellent ○: 0.8N / 15mm or more, less than 1.5N / 15mm: Usable ×: Less than 0.8N / 15mm: Not usable

[0070] (Open time evaluation) Using an adhesive strength tester (Type ASM-15N manufactured by JT Toshi Co., Ltd.), the hot melt adhesive was applied to cardboard (B-flute cardboard) at a coating rate of 36 cc / min and a coating speed of 30 m / min. 15 seconds after coating, the coated surface and the cardboard (B-flute cardboard) were pressed together at an adhesive pressure (1.6 g / cm 2 ), and 20 seconds after coating, the coated surface and the cardboard (B-flute cardboard) were pressed together with a pressure of 1.6 g / cm 2 After the two pieces were stuck together for 120 seconds, they were peeled off and visually inspected to see whether or not the paper broke over 80% or more of the adhesive area. ◎: More than 80% of the paper was broken in both test pieces A and B: the open time was long. Excellent ◯: Only test piece A was broken by 80% or more.: The open time was adequate. Usable. ×: 80% or more of the paper does not break in either test piece A or test piece B: Open time is short. Not usable.

[0071] (Evaluation of blocking properties) Ten heat-sensitive labels (coated paper, unprinted) measuring 4 cm x 5 cm were stacked, a 10 kg weight was placed on top, and the stacked pieces were placed in an oven at 50°C. After 24 hours, the stacked pieces were taken out and the heat-sensitive labels were peeled off. The resistance felt when the labels were peeled off was used to evaluate the blocking properties according to the following criteria. : No blocking, each sheet can be easily peeled off. : Excellent 〇: There is some blocking, but each sheet can be peeled off. : Usable ×: Completely blocked and cannot be peeled off one by one. : Not usable

[0072] (Jamming resistance evaluation) The jamming evaluation was performed using a thermal labeling machine (manufactured by Koyo Automatic Machinery Co., Ltd., model LR-400KC). A 6 cm wide label was cut at a length of 10 cm for 5 minutes at a label supply speed of 350 sheets / min, and the presence or absence of jamming during label cutting was visually evaluated. Jamming refers to a failure to feed the label. ◎: No jamming: Excellent ×: Jamming occurred: Unavailable

[0073] [Table 1]

[0074] [Table 2]

Claims

1. The composition comprises an ethylene-vinyl acetate copolymer (A), a tackifier resin (B), and a saturated fatty acid triglyceride (C), The ethylene-vinyl acetate copolymer (A) has a vinyl acetate content of 26% by mass or more and less than 45% by mass, The melt mass flow rate (MFR) of the ethylene-vinyl acetate copolymer (A) at 190° C. and 21.18 N, measured in accordance with JIS K7210, is 12 to 200 g / 10 min; The softening point of the tackifier resin (B) is 90 to 120° C., A hot melt adhesive, characterized in that the melting point of the saturated fatty acid triglyceride (C) is 65 to 100°C.

2. A composition comprising an ethylene-vinyl acetate copolymer (A), a tackifier resin (B), and a saturated fatty acid triglyceride (C), The ethylene-vinyl acetate copolymer (A) has a vinyl acetate content of 26% by mass or more and less than 45% by mass, The melt mass flow rate (MFR) of the ethylene-vinyl acetate copolymer (A) at 190° C. and 21.18 N, measured in accordance with JIS K7210, is 12 to 200 g / 10 min; The acid value of the tackifier resin (B) is 20 to 300 mgKOH / g (excluding 100 mgKOH / g or less), A hot melt adhesive, characterized in that the melting point of the saturated fatty acid triglyceride (C) is 65 to 100°C.

3. The hot melt adhesive according to claim 1 or 2, wherein the melt mass flow rate (MFR) of the ethylene-vinyl acetate copolymer (A) at 190°C and 21.18N, measured in accordance with JIS K7210, is 100 to 200 g / 10 min.

4. The hot melt adhesive according to claim 1 or 2, characterized in that the content of the ethylene-vinyl acetate copolymer (A) is 10 to 70 mass%, the content of the tackifier resin (B) is 10 to 70 mass%, and the content of the saturated fatty acid triglyceride (C) is 5 to 70 mass%, relative to a total of 100 mass% of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), and the saturated fatty acid triglyceride (C).

5. 3. A heat-sensitive label comprising an adhesive layer made of the hot melt adhesive according to claim 1 or 2.

6. A container having the heat-sensitive label according to claim 5 attached thereto.

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