Hot-melt adhesive, and heat-sensitive label using the same and container

Abstract

To provide a hot-melt adhesive which has a long open time, is excellent in blocking property, and can obtain good adhesion not only in a paper label but also in a plastic label such as PET and OPP, and a heat-sensitive label and a container which prevent jamming using the hot-melt adhesive.SOLUTION: A hot-melt adhesive contains an ethylene-vinyl acetate copolymer (A), a tackifier resin (B) and saturated fatty acid triglyceride (C), wherein a content of vinyl acetate of the ethylene-vinyl acetate copolymer (A) is 26 mass% or more and less than 45 mass%, a melt mass flow rate (MFR) of the ethylene-vinyl acetate copolymer (A) at 190°C and 21.18 N, which is measured according to JIS K 7210, is 12 to 200 g / 10 min, and a melting point of the saturated fatty acid triglyceride (C) is 65 to 100°C.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Hot melt adhesives are solvent-free, making them environmentally and work-friendly. Furthermore, after being heated and melted, they are applied to film or paper substrates, and then cooled and solidified, allowing them to be quickly wound up, making for compact coating machines. Furthermore, when substrates are bonded together in a heated and melted state, they quickly cool and solidify, providing instant adhesive properties, among other benefits.

[0003] Tack labels are often used for labels on glass 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 problems with the use of dicyclohexyl phthalate (DCHP), a suspected endocrine disruptor, as a solid plasticizer. Hot melt adhesives have problems such as a short open time that makes it difficult to achieve stable adhesion. Furthermore, there are issues such as the adhesive adhering to the labeler's cutter during labeling, causing jamming, and these have prevented them from becoming widely used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 55-16055 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-137438 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 their adhesiveness is unstable during labeling. Furthermore, while they have good adhesive properties for paper labels, they have the problem of poor adhesiveness for plastic labels such as polyethylene terephthalate (PET) and biaxially oriented polypropylene (OPP).

[0006] An object of the present invention is to provide a hot melt adhesive that has a long open time, excellent blocking properties, and 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 do not jam when using the hot melt adhesive. [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 attached. [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 vinyl acetate content of the ethylene-vinyl acetate copolymer (A) is 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 21.18N measured in accordance with JIS K7210 is 12 to 200 g / 10 min, and the melting point of the saturated fatty acid triglyceride (C) is 65 to 100°C.

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

[0009] [3] The hot melt adhesive, 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 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 hot melt adhesive.

[0011] [5] A container with the heat-sensitive label attached. [Effects 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 heat-sensitive labels and containers that do not jam when using this hot melt adhesive. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present disclosure will be described in detail below. It goes without saying that other embodiments are also included in the scope of the present invention as long as they are consistent with 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 when heated to become fluid or liquid. Furthermore, in this specification, a numerical range specified using "to" includes the numerical values ​​before and after "to" as the lower and upper limit values ​​of the range. Furthermore, unless otherwise noted, the various components appearing in this specification may each be used independently, either alone or in combination of two or more.

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

[0015] The hot melt adhesive of the present disclosure has a moderate open time, which allows for stable adhesion during labeling, and excellent blocking properties when solidified, making it 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). The hot melt composition of the present invention preferably contains 10 to 70% by mass of the ethylene-vinyl acetate copolymer (A), 10 to 70% by mass of the tackifier resin (B), and 5 to 70% by mass of the saturated fatty acid triglyceride, with the total being 100% by mass of the ethylene-vinyl acetate copolymer (A), tackifier resin (B), and saturated fatty acid triglyceride (C). By adjusting the ethylene-vinyl acetate copolymer (A) to 10 to 70% by mass, good adhesiveness (cohesion) is maintained, and a more preferred range is 20 to 50% by mass. By adjusting the tackifier resin (B) to 10 to 70% by mass, good adhesiveness (adhesion) is maintained, and a more preferred range is 20 to 50% by mass. By adjusting the saturated fatty acid triglyceride (C) to 5 to 70% by mass, good open time and anti-blocking properties are maintained, and a more preferred range is 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), tackifier resin (B), and saturated fatty acid triglyceride (C) is preferably 60 to 100% by mass. By setting the content within this range, adhesiveness and anti-blocking properties can be more effectively achieved. A more preferred range is 70 to 100% by mass, and an even more preferred 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, blocking properties decrease, and if the vinyl acetate content is less than 26% by mass, adhesive properties decrease. 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 anti-blocking properties 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 tackifying 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 adhesiveness and blocking properties, rosin-based tackifying resins such as rosin ester resin, hydrogenated rosin, acid-modified rosin, and hydrogenated rosin ester resin are preferred. Of these, acid-modified rosin is preferred, and maleic acid-modified rosin is particularly preferred.

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

[0022] <Saturated fatty acid triglyceride (C)> Generally, saturated fatty acid triglycerides refer to fats and oils that are liquid at room temperature due to their relatively low melting point and therefore contain a large amount of unsaturated fatty acid triglycerides, and are then hydrogenated to increase the proportion of saturated fatty acid triglycerides with higher melting points, 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 the saturated fatty acid triglyceride (C) in the present invention. From the viewpoints of blocking properties and adhesive properties, hydrogenated rapeseed oil is preferred.

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

[0024] The saturated fatty acid in the saturated fatty acid triglyceride (C) preferably 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 as long as the effects of the present invention are not impaired. 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 but less than 45% by mass, waxes, colorants, antiblocking agents, inorganic fillers, antioxidants, bulking agents, flame retardants, plasticizers, antistatic agents, light stabilizers, ultraviolet absorbers, and heavy metal deactivators. 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, 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% to 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) relative to the ethylene-vinyl acetate copolymer (A) is preferably 50% by mass or less, more preferably 30% by mass or less. By keeping the content of (XA) relative to (A) at 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 properties of the hot melt adhesive. Examples of waxes include carnauba wax, candelilla wax, montan wax, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, polypropylene wax, and oxides of these waxes. Other examples include ethylene-acrylic acid copolymer wax and ethylene-methacrylic acid copolymer wax.

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

[0029] Examples of the anti-blocking agent include 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, flaked 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 nanotubes, graphite, copper, silver, aluminum, nickel, iron, calcium fluoride, mica, montmorillonite, and apatite.

[0031] Examples of the antioxidant 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, nickel dibutyl dithiocarbamate, 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 flame retardants, halogen-containing compound flame retardants, sulfonic acid metal salt flame retardants, and silicon-containing compound flame retardants.

[0034] Examples of the plasticizer include phthalate ester-based plasticizers, polyester-based plasticizers, aliphatic dibasic acid ester-based plasticizers, aliphatic monobasic acid ester-based plasticizers, phosphate ester-based plasticizers, citrate ester-based plasticizers, epoxy-based plasticizers, trimellitate ester-based plasticizers, tetrahydrophthalate ester-based plasticizers, glycol-based 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 ester 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 absorber include benzophenone-based ultraviolet absorbers, triazine-based ultraviolet absorbers, and benzotriazole-based ultraviolet absorbers.

[0038] Examples of the heavy metal deactivator include salicylic acid derivatives, hydrazide derivatives, and oxalic acid amide derivatives.

[0039] <Hot melt adhesive manufacturing> The hot melt adhesive of the present invention can be produced, for example, by adding the ethylene-vinyl acetate copolymer (A) and the tackifying resin (B) to a melting pot equipped with a stirrer to melt the saturated fatty acid triglyceride (C). Alternatively, the hot melt adhesive of the present invention may 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 granules, pellets, sheets, and blocks. These methods can be performed using any known method without limitation.

[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 then cooling it. An example of a method for applying a hot-melt adhesive to a label substrate is to heat it to a liquid state 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 in 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 adhesiveness and jamming prevention. 2 10 to 15 g / m 2 is more preferred. The coating may be full surface coating, partial coating such as linear, lattice, wave, or dot coating, or a combination of these.

[0045] <Containers with heat-sensitive labels> Containers to which the heat-sensitive label of the present invention can be applied include glass, ceramic, plastic, or metal containers. Heat-sensitive label application methods include heating the label and applying it to the bottle, or, when in-mold molding plastic containers, placing the label in a mold beforehand and adhering it to the container using the heat generated during molding. The heat-sensitive label may wrap around the entire container. Glass bottles, which are one type of container used in the present invention, can be transparent, amber, or colored bottles (e.g., blue, red, or green). The surface of the glass bottle can 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 also be applied to glass products other than glass bottles, metal products such as metal containers, and other materials.

[0046] Plastics, which are one type of container of the present invention, can be any material that can be used as a container by itself, such as olefins such as high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and polypropylene, as well as polystyrene, polyester (PET, etc.), polycarbonate, and vinyl chloride. Furthermore, if a multilayer structure is possible, a foam layer can be placed on one side of the container to improve the impact resistance of the container, and the same resin can be extruded without foaming to create a multilayer container. In-mold molding methods include vacuum forming, pressure forming, extrusion blow molding, injection molding, injection blow molding, and biaxial stretch blow molding.

[0047] When applying a label to the exterior surface of a resin container, such as a polyolefin container or a polyethylene terephthalate container, using processes such as vacuum forming, pressure forming, extrusion blow molding, injection molding, injection blow molding, and biaxial stretch blow molding, an in-mold labeling method is known in which an in-mold label is pre-positioned on the cavity surface of a molding die and then heat-sealed to the exterior surface of the container as the container is being molded. This in-mold labeling method has the advantage that the in-mold label can be adhered to the entire exterior surface of the container, making the label less likely to peel off from the container and facilitating large-area labeling. Furthermore, this method is preferred because it can increase the rigidity of the container, enable the container to be made thinner, provide excellent design, and enable labor-saving and space-saving processes.

[0048] These application methods allow a heat-sensitive label with a hot-melt adhesive layer (not sticky at room temperature) to be applied to an adherend while heating, eliminating the need for release paper, preventing contamination of the application machine, making it easy to align the labeling, and preventing blocking during normal transportation and handling. Eliminating the need for release paper also reduces waste, making these labels environmentally friendly.

[0049] The use of the hot melt adhesive of the present invention can significantly 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 long open time of the hot melt allows it to easily adhere to the substrate even if the heat of the hot melt adhesive is absorbed by the substrate. [Example]

[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. Unless otherwise specified, "parts" and "%" in the examples represent "parts by mass" and "% by mass", respectively.

[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 plastometer was heated and pressurized (21.18 N) at 190°C, and the amount of resin extruded from the opening at the bottom of the container in 10 minutes was measured.

[0052] [Measuring the melting point of saturated fatty acid triglycerides (C)] The melting point of saturated fatty acid triglyceride (C) was measured by the melting point measurement method described in the Japanese Standards of Food Additives (8th edition). Specifically, dried powdered saturated fatty acid triglyceride was placed in a capillary tube, tightly packed, and then heated to approximately 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 in accordance with 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 using a bulb-type automatic softening point tester ASP-KG4 (manufactured by Meitex Co., Ltd.) was taken as the melting point.

[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 95% ethanol (V / V), and the acid value was determined by titration with phenolphthalein indicator.

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

[0056] XA-1: Ultrathene 722 (manufactured by 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: 20 g / 10 min)

[0057] ·Tackifying resin (B) B-1: KE-604B (Arakawa Chemical Co., Ltd., acrylic acid modified rosin, softening point: 129°C, acid value: 246 mg KOH / g) B-2: Haritac 4821 (Harima Chemicals, maleic acid modified rosin, softening point: 107°C, acid value: 22.5 mg KOH / 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 (manufactured by Arakawa Chemical Industries, Ltd., rosin ester, softening point: 105°C, acid value: none) B-6: T-REZ HA85 (ENEOS Corporation, 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 & Fat Industries Co., Ltd., melting point: 70°C) C-2: Hardened castor oil (manufactured by Yokoseki Oil & Fat Industries Co., Ltd., 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: Extremely hardened palm oil (manufactured by Yokoseki Oil & Fat Industries Co., Ltd., melting point: 59°C)

[0060] Additives (D) D-1: Antioxidant: IRGANOX 1010 (manufactured by 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 part of additive (D) IRGANOX 1010, and 0.2 parts of silicone KF96 100CS were placed in a container and heated to 150°C to melt. Then, while stirring with a stirrer, 40 parts of ethylene-vinyl acetate copolymer (A-2) and 30 parts of tackifier resin (B-2) were gradually added. The ethylene-vinyl acetate copolymer was completely dissolved, yielding the hot melt adhesive of Example 1.

[0062] Example 2: Preparation of hot melt adhesive 20 parts of saturated fatty acid triglyceride (C-1) and 0.1 part of additive (D) IRGANOX 1010 were placed in a container and heated to 150°C to melt, 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, yielding the hot melt adhesive of Example 2.

[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 strength 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) IRGANOX 1010 were placed in a container and heated to 150°C to melt, and then 30 parts of ethylene-vinyl acetate copolymer (XA-2) and 30 parts of tackifying resin (B-2) were gradually added while stirring with a stirrer. The ethylene-vinyl acetate copolymer was completely dissolved, yielding the hot melt adhesive of Comparative Example 1.

[0065] (Comparative Example 2) 50 parts of saturated fatty acid triglyceride (C-1) and 0.1 parts of additive (D) IRGANOX 1010 were placed in a container, heated and melted at 150°C, and then 50 parts of tackifier resin (B-5) were 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) IRGANOX 1010 were placed in a container and heated to 150°C to melt, and then 50 parts of ethylene-vinyl acetate copolymer (A-2) was gradually added while stirring with a stirrer. The ethylene-vinyl acetate copolymer was completely dissolved, yielding the hot melt adhesive of Comparative Example 3.

[0067] Comparative Example 4 30 parts of saturated fatty acid triglyceride (XC-1) and 0.1 parts of additive (D) IRGANOX 1010 were placed in a container and heated to 150°C to melt, 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, yielding the hot melt adhesive of Comparative Example 4.

[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 for each of the following. Coated paper: 84.9 g / m 2 (No printing) OPP: 40 μm OPP film (no corona treatment) PET: 25 μm 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] (Adhesion evaluation) The adhesiveness was evaluated using unstretched polypropylene (CPP, thickness: 500 μm) as the adherend, and the following evaluation was carried out, with the best evaluation result being adopted. Using a heat sealer (Tester Sangyo Co., Ltd., TP-701-G Heat Seal Tester Thermal Inclination Type), the heat-sensitive label and the adherend were heat-sealed for 1 second at a temperature of 140°C and a pressure of 0.1 MPa, and then stored in a constant temperature and humidity room at a temperature of 23°C and a humidity of 65% for at least 24 hours. Evaluation was performed using a tensile tester, where the labels were peeled off at a speed of 300 mm / min, 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: Unusable

[0070] (Open time evaluation) Using an adhesive strength tester (Type ASM-15N manufactured by JT Toshi Corporation), the hot melt adhesive was applied to corrugated board (B-flute corrugated board) at a coating rate of 36 cc / min and a coating speed of 30 m / min. 15 seconds after application, the coated surface and the corrugated board (B-flute corrugated board) 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 bonded 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 if the paper broke over 80% or more of the adhesive area. ◎: 80% or more of the paper was broken in both test piece A and test piece B: long open time. Excellent ◯: Only test piece A broke by 80% or more: Has a moderate open time. Usable ×: Neither test piece A nor test piece B broke 80% or more of the paper: Open time was short. Unusable.

[0071] (Evaluation of blocking properties) Ten 4cm x 5cm heat-sensitive labels (coated paper, no printing) were stacked, a 10kg weight was placed on top of them, and they were placed in an oven at 50°C. After 24 hours, they were removed and the heat-sensitive labels were peeled off. The resistance felt when peeling them off was used to evaluate the blocking properties according to the following criteria. ◎: No blocking occurs and each sheet can be easily peeled off. : Excellent 〇: There is some blocking, but the sheets can be peeled off one by one. : Usable ×: Completely blocked and unable to peel off the sheets one by one. : Unusable

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

[0073] [Table 1]

[0074] [Table 2]

Claims

1. The composition comprises an ethylene-vinyl acetate copolymer (A), a tackifying 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 21.18N, measured in accordance with JIS K7210, is 12 to 200 g / 10 min; A hot melt adhesive characterized in that the saturated fatty acid triglyceride (C) has a melting point of 65 to 100°C.

2. 2. The hot melt adhesive according to claim 1, wherein the softening point of the tackifier resin (B) is 80 to 120°C.

3. 2. The hot melt adhesive according to claim 1, wherein 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).

4. A heat-sensitive label having an adhesive layer made of the hot melt adhesive according to any one of claims 1 to 3.

5. A container to which the heat-sensitive label according to claim 4 is attached.

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