Resin composition and lid member

Abstract

The purpose of the present invention is to provide: a resin composition which exhibits excellent adhesion to plastic containers, especially, containers comprising poly(ethylene terephthalate), polystyrene, polypropylene, poly(vinyl chloride) and poly(lactic acid) as materials and which can be advantageously used as a sealant layer of a lid member of a container; and a lid member.　The present invention uses a resin composition which contains: 50-94.5 parts by weight of an ethylene-vinyl acetate copolymer (A); 5-30 parts by weight of a tackifying resin (B); and 0.5-25 parts by weight of a layered filler (CI) or fine particles (CII) having an average primary particle diameter of 0.001-1 μm (here, the total amount of components (A), (B), (CI) and (CII) is 100 parts by weight).

Description

Resin composition and lid material

[0001] The present invention relates to a resin composition used for a lid material of a container and a lid material having the same as a sealant layer.

[0002] Conventionally, plastic containers made of materials such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, and polylactic acid (PLA), as well as paper containers made primarily of paper, have been used to package foods, beverages, pharmaceuticals, industrial parts, and the like. The lids used for these containers are made of films that have stable adhesive properties to protect the contents and that are easily peelable, allowing them to be opened with appropriate strength when peeled off.

[0003] Although many easily peelable films have been known for use with containers made of polypropylene, polystyrene, and the like, no practically superior easily peelable films have been found for containers made of amorphous polyethylene terephthalate (A-PET), crystalline polyethylene terephthalate (C-PET), or PLA, the demand for which has been increasing in recent years due to growing awareness of environmental conservation. Conventional easily peelable films have a problem of their lids opening due to vibration or dropping during transportation or storage due to their weak adhesive strength. In addition, some A-PET containers have a silicone coating applied to their surfaces during the production process, which further reduces adhesive strength, making them unsuitable for practical use with such containers.

[0004] Generally, mixtures of polyethylene, ethylene-vinyl acetate copolymer, ethylene-α-olefin copolymer, etc., and a tackifier are known as adhesives for lid material sealants, but these materials do not provide sufficient adhesive strength. Also, resin compositions comprising an ethylene-α-olefin copolymer, an olefin-based elastomer and / or a styrene-based elastomer, and a tackifier (see, for example, Patent Document 1), and sealing materials comprising an ethylene-α-olefin copolymer, an ethylene-polar monomer copolymer, an A-B-A type block copolymer, and a tackifier (see, for example, Patent Document 2) have been used, but these do not fully satisfy the adhesive strength required for practical use. Therefore, a lid material that can be suitably used for these applications has been desired.

[0005] Japanese Patent Publication No. 1999-269319 Japanese Patent No. 4438108

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a resin composition and a lid material that have excellent adhesion to plastic containers, particularly containers made from polyethylene terephthalate, polystyrene, polypropylene, polyvinyl chloride, and polylactic acid, and that can be suitably used as a sealant layer for the lid material of the container.

[0007] As a result of intensive research aimed at solving the above problems, the present inventors have found that a resin composition containing an ethylene-vinyl acetate copolymer, a tackifier, and a layered filler or fine particles having an average primary particle diameter in the range of 0.001 to 1 μm has excellent adhesion to various plastic containers, and have completed the present invention.

[0008] That is, the respective aspects of the present invention are the following [1] to

[11] . [1] A resin composition comprising 50 to 94.5 parts by weight of an ethylene-vinyl acetate copolymer (A), 5 to 30 parts by weight of a tackifier resin (B), and 0.5 to 25 parts by weight of a layered filler (CI) or fine particles (CII) having an average primary particle diameter in the range of 0.001 to 1 μm (wherein the total of (A), (B), (CI), and (CII) is 100 parts by weight). [2] The resin composition according to the above [1], further comprising 0.5 to 20 parts by weight of a compatibilizer (D) per 100 parts by weight of the resin composition. [3] The resin composition according to the above [2], wherein the compatibilizer (D) is a hydrogenated product of a polystyrene-polybutadiene-polystyrene block copolymer and has a styrene content of 5 to 20% by weight. [4] For 100 parts by weight of the resin composition, the density measured according to JIS K6922-1 is 860 to 910 kg / m ３ [5] The resin composition according to any one of the above [1] to [3], further comprising 5 to 100 parts by weight of an ethylene / α-olefin copolymer (E) having a density of 910 to 940 kg / m as measured according to JIS K6922-1, per 100 parts by weight of the resin composition. ３The resin composition according to any one of [1] to [4] above, further comprising 5 to 100 parts by weight of a low-density polyethylene (F) having a melting point in the range of 98 to 120°C as measured according to JIS K6924-2. [6] The resin composition according to any one of [1] to [5] above, wherein the tackifier resin (B) is at least one selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, alicyclic hydrogenated petroleum resins, and copolymerized petroleum resins. [7] The resin composition according to any one of [1] to [6] above, wherein the layered filler (CI) is talc. [8] The resin composition according to any one of [1] to [7] above, wherein the fine particles (CII) are calcium carbonate. [9] A sealant adhesive comprising the resin composition according to any one of [1] to [8] above.

[10] The sealant adhesive according to [9] above, which is for a container made of at least one resin selected from the group consisting of polyethylene terephthalate, polystyrene, polypropylene, polyvinyl chloride, and polylactic acid.

[11] A lid material having a configuration including at least two layers: a layer containing the resin composition according to any one of [1] to [8] above, and a supporting substrate layer.

[0009] According to the present invention, a resin composition can be provided that has excellent adhesion to various types of plastic containers, particularly containers made from polyethylene terephthalate, polystyrene, polypropylene, polyvinyl chloride, and polylactic acid, and is useful for producing a sealant layer for the lid material of the container.

[0010] The present invention will be described in detail below.

[0011] A resin composition according to one embodiment of the present invention comprises 50 to 94.5 parts by weight of an ethylene-vinyl acetate copolymer (A), 5 to 30 parts by weight of a tackifier resin (B), and 0.5 to 25 parts by weight of a layered filler (CI) or fine particles (CII) having an average primary particle diameter in the range of 0.001 to 1 μm.

[0012] The ethylene-vinyl acetate copolymer (A) preferably has a vinyl acetate content of 3 to 28% by weight, more preferably 3 to 20% by weight, and even more preferably 3 to 15% by weight. A vinyl acetate content of 3% by weight or more is preferred because the resulting composition has excellent low-temperature heat-sealing properties, while a vinyl acetate content of 28% by weight or less is preferred because the resulting composition has excellent blocking resistance and adhesive strength. Here, the vinyl acetate content in the ethylene-vinyl acetate copolymer can be measured by a method in accordance with JIS K 6924-1.

[0013] The ethylene-vinyl acetate copolymer (A) preferably has a melt flow rate in the range of 0.5 to 30 g / 10 min, particularly 1.0 to 15 g / 10 min, measured in accordance with JIS K 6924-1 at a temperature of 190°C and a load of 21.18 N. A melt flow rate of 0.5 g / 10 min or more is preferred because the resulting sealant adhesive has excellent adhesive strength and high-speed moldability, while a melt flow rate of 30 g / 10 min or less is preferred because the resulting resin composition has excellent stability during molding processing.

[0014] The ethylene-vinyl acetate copolymer (A) can be obtained by a known production method, and the production method is not particularly limited. For example, a method of radical polymerization under high pressure using a tubular reactor or a vessel reactor can be mentioned.

[0015] Furthermore, the ethylene-vinyl acetate copolymer (A) may be either a single component or a composition containing two or more types of ethylene-vinyl acetate copolymers.

[0016] The ethylene-vinyl acetate copolymer (A) may be a commercially available product, such as Ultrathene (registered trademark) 537 (trade name, manufactured by Tosoh Corporation).

[0017] The tackifier resin (B) can be any resin that falls within the category of tackifier resins, including synthetic petroleum resin-based tackifiers such as petroleum resins, coumarone resins, and styrene-based tackifiers, and natural resin-based tackifiers such as rosin-based resins, methyl ester-based resins, glycerin ester-based resins, pentaerythritol ester-based resins, terpene-based resins, and modified versions thereof. Among these tackifier resins, synthetic petroleum resin-based tackifiers include aliphatic petroleum resins, aliphatic hydrogenated petroleum resins, aromatic petroleum resins, aromatic hydrogenated petroleum resins, alicyclic petroleum resins, alicyclic hydrogenated petroleum resins, and copolymerized hydrogenated petroleum resins. Tackifier resins selected from at least one selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, alicyclic hydrogenated petroleum resins, and copolymerized petroleum resins are particularly preferred because of their excellent adhesion and hygiene, such as reduced odor and coloration.

[0018] The tackifier resin (B) preferably has a softening temperature measured by the ring and ball method in the range of 90 to 150° C., more preferably in the range of 100 to 145° C., and even more preferably in the range of 110 to 140° C. If the softening temperature is 90° C. or higher, the resulting resin composition will have excellent adhesive properties, and if the softening temperature is 150° C. or lower, the tackifier resin will be excellent in terms of production stability.

[0019] Commercially available tackifier resins can be used as the tackifier resin (B). Specific examples of synthetic petroleum resins include (trade names) Arcon (registered trademark) P100, Arcon (registered trademark) P125, Arcon (registered trademark) P140, Arcon (registered trademark) M90, Arcon (registered trademark) M115, and Arcon (registered trademark) M135 (all manufactured by Arakawa Chemical Industries, Ltd.), Imave (registered trademark) S110, Imave (registered trademark) P125 (all manufactured by Idemitsu Kosan Co., Ltd.), T-REZ (registered trademark) RC115, and T-REZ (registered trademark) HA125 (all manufactured by ENEOS Corporation). Examples of rosin-based resins include Pine Crystal (registered trademark) KE-311 (manufactured by Arakawa Chemical Industries, Ltd.). Examples of terpene-based resins include YS Resin PX1150 and YS Resin PX1150N (all manufactured by Yasuhara Chemical Co., Ltd.).

[0020] The layered filler (CI) can be any material that falls within the category of layered fillers. Examples of layered fillers include serpentine-kaolin group minerals (lizardite, amesite, kaolinite, dickite, nacrite, halloysite, etc.), talc-pyrophyllite group minerals (talc, willemsite, pyrophyllite, etc.), smectite group minerals (saponite, hectorite, sauconite, stevensite, montmorillonite, beidellite, nontronite, etc.), vermiculite group minerals (vermiculite, etc.), mica or mica group minerals (biotite, phlogopite, iron mica, muscovite, celadonite, illite, clintonite, etc.), chlorite group minerals (clinochlore, chamosite, donbassite, cookeite, etc.), layered hydrated oxides (hydrotalcite, etc.), and graphite.

[0021] When mixed with the ethylene-vinyl acetate copolymer (A) and the tackifier (B), the layered filler (CI) can form individual layers by delamination, resulting in excellent dispersibility in the resin composition, making it more preferable than spherical or other fillers. When such a resin composition is used as a film, the layered filler (CI) is incompatible with the ethylene-vinyl acetate copolymer (A) and the tackifier (B), and therefore stress applied to the film can be absorbed by the formation of voids at the interface between the ethylene-vinyl acetate copolymer (A) and the tackifier (B) and the layered filler (CI). In other words, when used as a lid material film for plastic containers, the stress generated when peeling the lid material film from the container is absorbed by the formation of voids, requiring a stronger stress, resulting in improved adhesive strength.

[0022] These layered fillers (CI) may be used without treatment, but if necessary, layered fillers modified with organic ions or surface-treated with a surface treatment agent may also be used. In particular, when the particle size of the layered filler is small, it is preferable to perform a surface treatment in order to prevent aggregation of the layered fillers and to disperse them uniformly in the thermoplastic resin. Examples of surface treatment agents include higher fatty acids or derivatives thereof such as esters and salts (e.g., stearic acid, oleic acid, palmitic acid, calcium stearate, magnesium stearate, aluminum stearate, stearic acid amide, stearic acid ethyl ester, stearic acid methyl ester, calcium oleate, oleic acid amide, oleic acid ethyl ester, calcium palmitate, palmitic acid amide, palmitic acid ethyl ester, etc.); silane coupling agents (e.g., vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, etc.); titanium coupling agents (e.g., isopropyl triisostiaroyl titanate, isopropyl trilauryl myristyl titanate, isopropyl isostearoyl dimethacrylic titanate, isopropyl tridiisooctyl phosphate titanate, etc.).

[0023] The average particle diameter of the layered filler (CI) is preferably in the range of 0.1 to 50 μm, and more preferably in the range of 0.2 to 20 μm. This average particle diameter can be measured by a laser diffraction method in accordance with JIS Z8825. If the resolution of a scanning electron microscope is low, another electron microscope such as a transmission electron microscope may also be used. Specifically, if the particle shape is spherical, the diameter is considered to be the diameter; if the particle shape is non-spherical, the average of the longest and shortest diameters is considered to be the diameter. The average particle diameter is determined by the average diameter of 20 particles randomly selected by observation with a scanning electron microscope or the like. When using the laser diffraction method, the layered filler (CI) can be thoroughly dispersed in a dispersant using a stirrer and / or ultrasonic vibrator, and then determined from the particle size value at 50% cumulative mass read from the measured particle size cumulative curve.

[0024] As the layered filler (CI), the layered fillers listed above may be used alone or in combination of two or more selected therefrom.

[0025] As the fine particles (CII), any fine particles can be used as long as they belong to the category of fine particles, and inorganic fine particles, organic fine particles, etc. can be used. Examples of inorganic fine particles include metal atoms in Groups 1 to 13 of the periodic table (e.g., Fe, Na, K, Cu, Mg, Ca, Zn, Ba, Al, Ti, Zr) or silicon simple substances, oxides, hydroxides, carbonates, sulfates, silicates, sulfites, and titanates; various clay minerals in which some of these compounds exist; and others, such as iron oxide, zinc oxide, titanium oxide, zirconium oxide, alumina, silica, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, magnesium carbonate, calcium carbonate, barium sulfate, calcium sulfate, sodium sulfate, calcium sulfite, barium titanate, calcium silicate, calcium aluminum silicate, calcium aluminum silicate sodium, clay, wollastonite, glass beads, glass powder, silica sand, silica stone, quartz powder, shirasu, diatomaceous earth, white carbon, iron powder, aluminum powder, kaolin, talc, carbon fiber, carbon nanotubes, mica, and wollastonite. These inorganic fine particles may be used without treatment, or may be surface-treated with a surface treatment agent as needed. In particular, when the particle diameter of the inorganic fine particles is small, it is preferable to perform a surface treatment in order to prevent aggregation of the inorganic fine particles and to disperse them uniformly in the thermoplastic resin.Examples of surface treatment agents include higher fatty acids or derivatives thereof such as esters and salts (e.g., stearic acid, oleic acid, palmitic acid, calcium stearate, magnesium stearate, aluminum stearate, stearic acid amide, stearic acid ethyl ester, stearic acid methyl ester, calcium oleate, oleic acid amide, oleic acid ethyl ester, calcium palmitate, palmitic acid amide, palmitic acid ethyl ester, etc.); silane coupling agents (e.g., vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, etc.); titanium coupling agents (e.g., isopropyl triisostiaroyl titanate, isopropyl trilauryl myristyl titanate, isopropyl isostearoyl dimethacrylic titanate, isopropyl tridiisooctyl phosphate titanate, etc.).

[0026] Examples of organic fine particles include crosslinked acrylic particles, polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate, polyethylene naphthalate, polystyrene, melamine resin, cyclic olefin copolymer, polyethylene sulfide, polyimide, polyethyl ether ketone, polyphenylene sulfide, cork, and wood flour. Crosslinked acrylic particles are particles of crosslinked acrylic resin. They may be homopolymers or copolymers of acrylic monomers, or copolymers of acrylic monomers and other monomers, and the method for producing the crosslinked acrylic particles is not particularly limited. Examples of such crosslinked acrylic particles include polymethyl acrylate, polyethyl acrylate, polymethacrylic acid, polymethyl methacrylate, and polyethyl methacrylate.

[0027] As the fine particles (CII), one kind may be selected from the inorganic fine particles and organic fine particles and used alone, or two or more kinds may be selected and used in combination. When two or more kinds are used in combination, the inorganic fine particles and the organic fine particles may be mixed and used.

[0028] When the resin composition is used as a film, these fine particles (CII) are incompatible with the ethylene-vinyl acetate copolymer (A) and the tackifier resin (B), and therefore, stress applied to the film can be absorbed by forming voids at the interfaces between the ethylene-vinyl acetate copolymer (A) and the tackifier resin (B) and the fine particles (CII). In other words, when the resin composition is used as a lid material film for a plastic container, the stress generated when peeling the lid material film from the container is absorbed by forming voids, requiring a stronger stress, and as a result, the adhesive strength can be improved.

[0029] The average primary particle diameter of the fine particles (CII) is in the range of 0.001 to 1 μm, preferably in the range of 0.003 to 0.7 μm, and more preferably in the range of 0.005 to 0.5 μm. When the average primary particle diameter is 0.001 μm or more, aggregation of the fine particles is unlikely to occur and they are uniformly dispersed throughout the resin composition, which is preferable. When the average primary particle diameter is 1 μm or less, the transparency of the resin composition when made into a film is good, and further, the contact surface area between the ethylene-vinyl acetate copolymer (A) and the tackifier resin (B) and the fine particles (CII) is sufficiently large, which is preferable because the adhesive strength to a plastic container is high.

[0030] The average primary particle diameter of the fine particles (CII) can be measured using a scanning electron microscope (FE-SEM), and when the resolution of the scanning electron microscope is low, it may be measured using another electron microscope such as a transmission electron microscope in combination. Specifically, when the particle shape is spherical, the diameter is considered to be the diameter, and when the particle shape is non-spherical, the average of the longest and shortest diameters is considered to be the diameter, and the average of the diameters of 20 particles randomly selected by observation using a scanning electron microscope or the like is taken to be the average primary particle diameter.

[0031] The blending ratios of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), and the layered filler (CI) or the fine particles (CII) are as follows: Here, the total of (A), (B), (CI), and (CII) is 100 parts by weight.

[0032] The blending ratio of the ethylene-vinyl acetate copolymer (A) is 50 to 94.5 parts by weight, preferably 52 to 90 parts by weight, and more preferably 60 to 87 parts by weight. When the blending ratio of (A) is 50 parts by weight or more, the resulting resin composition has excellent moldability, and when it is 94.5 parts by weight or less, the resulting resin composition has good adhesiveness.

[0033] The blending ratio of the tackifier resin (B) is 5 to 30 parts by weight, preferably 8 to 28 parts by weight, and more preferably 10 to 25 parts by weight. When the blending ratio of (B) is 5 parts by weight or more, the resulting resin composition has excellent adhesiveness, and when it is 30 parts by weight or less, blocking during molding processing is reduced.

[0034] The blending ratio of the layered filler (CI) or the fine particles (CII) is 0.5 to 25 parts by weight, preferably 2 to 20 parts by weight, and more preferably 3 to 15 parts by weight. When the blending ratio of (CI) or (CII) is 0.5 part by weight or more, the resulting resin composition has excellent adhesiveness, and when it is 25 parts by weight or less, the resulting resin composition has excellent transparency and moldability.

[0035] The resin composition according to one embodiment of the present invention may further contain a compatibilizer (D). By including the compatibilizer (D), the layered filler (CI) or the fine particles (CII) can be dispersed more uniformly in the resin composition, further improving the adhesive strength to various containers. Any compatibilizer (D) can be used as long as it exhibits such a compatibilizing effect. Examples of the compatibilizer include oxidized polyolefins and acid-modified polyolefins, which are obtained by partially oxidizing polyethylene, polypropylene, and copolymerized olefin resins thereof, and those obtained by reacting carboxylic acid groups such as maleic anhydride and itaconic anhydride.

[0036] Other examples of the compatibilizer (D) include thermoplastic block copolymers containing at least one of an olefin and a diolefin as a structural unit and a vinyl aromatic hydrocarbon as a structural unit, such as those represented by the following formula:

[0037] (A-B)n (A-B)n-A' or (A-B)m-X (wherein A and A' each independently represent a vinyl aromatic hydrocarbon polymer block. B represents a polymer block of either an olefin or a diolefin. n represents an integer of 1 to 5, m represents an integer of 2 to 7, and X represents an m-valent polyfunctional compound.) The thermoplastic block copolymer is a polymer having at least one of a linear structure, a radial structure, and a branched structure, and having a block structure in which at least one end is a vinyl aromatic hydrocarbon polymer block. The thermoplastic block copolymer may be a hydrogenated product thereof.

[0038] Examples of the vinyl aromatic hydrocarbon to be used here include styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene, vinylxylene, ethylvinylxylene, vinylnaphthalene, and mixtures thereof, etc. Of these, styrene is particularly preferred.

[0039] Examples of the olefins that can be used include α-olefins such as ethylene, propylene, and 1-butene, and examples of the diolefins that can be used include conjugated diolefins such as butadiene and isoprene.

[0040] As such a thermoplastic block copolymer, as long as olefin units predominate in block B, a copolymer of either an olefin or a conjugated diolefin with a vinyl aromatic hydrocarbon is preferably used, and a hydrogenated polymer block obtained by polymerizing a conjugated diolefin is more preferably used. In the present invention, a thermoplastic block copolymer of a vinyl aromatic hydrocarbon having vinyl aromatic hydrocarbon polymer blocks at both ends with an olefin or a diolefin is also preferred, and a hydrogenated product of a polystyrene-polybutadiene-polystyrene block copolymer (styrene-ethylene / butylene-styrene triblock copolymer, hereinafter referred to as "hydrogenated SEBS") is particularly preferred from the viewpoint of improving thermal stability.

[0041] Although there are no particular limitations on such hydrogenated SEBS, the styrene content is preferably 1 to 50% by weight, more preferably 3 to 35%, and even more preferably 5 to 20% by weight, because the effect of the styrene as a compatibilizer results in a resin composition having excellent adhesive strength. Furthermore, when a mixture of a hydrogenated styrene-butadiene diblock copolymer and a hydrogenated styrene-butadiene-styrene triblock copolymer is used as such hydrogenated SEBS, the mixing ratio is preferably 5 / 5 to 1 / 9.

[0042] As the compatibilizer (D), the above-mentioned compatibilizers may be used alone or in combination of two or more thereof.

[0043] The blending ratio of the compatibilizer (D) is preferably 0.5 to 20 parts by weight, more preferably 0.8 to 18 parts by weight, and even more preferably 1 to 15 parts by weight, relative to 100 parts by weight of the total of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), and the layered filler (CI) or the fine particles (CII). When the blending ratio of (D) is 0.5 parts by weight or more, the resulting resin composition has excellent adhesive properties, and when it is 20 parts by weight or less, the resulting resin composition has excellent cost performance and moldability, which is preferable.

[0044] The resin composition according to one embodiment of the present invention may further contain an ethylene-α-olefin copolymer (E). Any ethylene-α-olefin copolymer (E) can be used as long as it falls within the category generally referred to as an ethylene-α-olefin copolymer. The α-olefin is not particularly limited, but examples thereof include propene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, and 1-dodecane, each having 3 to 12 carbon atoms. These ethylene-α-olefin copolymers (E) can be suitably produced by copolymerizing ethylene and an α-olefin using a Ziegler catalyst, a chromium catalyst, or a metallocene catalyst. Examples of polymerization methods include solution polymerization, high-pressure polymerization, and gas-phase polymerization.

[0045] The ethylene-α-olefin copolymer (E) is excellent in smoothness at the time of peeling and sealing strength, and therefore has a density measured in accordance with JIS K6922-1 (1998) of 860 to 910 kg / m ３ It is preferable that the range is:

[0046] The blending ratio of the ethylene-α-olefin copolymer (E) is preferably 5 to 100 parts by weight, more preferably 10 to 50 parts by weight, and even more preferably 15 to 40 parts by weight, relative to 100 parts by weight of the total of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), and the layered filler (CI) or the fine particles (CII).

[0047] The resin composition according to one embodiment of the present invention may further contain a low-density polyethylene (F).

[0048] The low-density polyethylene (F) constituting the resin composition of the present invention is a low-density polyethylene obtained by polymerizing only ethylene using a known high-pressure polymerization method, and has a density range of 910 to 940 kg / m as measured according to JIS K6922-1. ３ The melting point of the low-density polyethylene (F) is preferably in the range of 98 to 120°C, more preferably in the range of 100 to 110°C.

[0049] The blending ratio of the low-density polyethylene (F) is preferably 5 to 100 parts by weight, more preferably 10 to 50 parts by weight, and even more preferably 15 to 40 parts by weight, relative to 100 parts by weight of the total of the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), and the layered filler (CI) or the fine particles (CII).

[0050] The low-density polyethylene (F) may be commercially available, and specific examples thereof include (trade names) Petrothene (registered trademark) (manufactured by Tosoh Corporation), Novatec (registered trademark) LD (manufactured by Japan Polyethylene Corporation), and Sanwax (registered trademark) (manufactured by Sanyo Chemical Industries, Ltd.).

[0051] The resin composition of the present invention may be blended with other thermoplastic resins or rubbers, as well as light stabilizers, ultraviolet absorbers, nucleating agents, lubricants, antioxidants, antiblocking agents, flow improvers, mold release agents, flame retardants, colorants, inorganic neutralizing agents, hydrochloric acid absorbers, fillers, conductive agents, and the like, within the scope of not impairing the effects of the present invention.

[0052] There are no particular limitations on the method for preparing the resin composition, and examples thereof include a method in which the ethylene-vinyl acetate copolymer (A), the tackifier resin (B), the layered filler (CI) or the fine particles (CII), and materials to be added thereto are pre-blended simultaneously in a mixer such as a Henschel mixer or a tumbler, and then melt-kneaded in a single-screw or twin-screw extruder.

[0053] The sealant adhesive, which is one embodiment of the present invention, will be described in detail below.

[0054] The resin composition can be used as an adhesive. In particular, the resin composition can be suitably used as a sealant adhesive for plastic containers whose main components are resins such as polyethylene terephthalate, polystyrene, polypropylene, etc., and various other resins, particularly as a lid sealant adhesive. Here, "sealant" means that it is used for sealing a container. By using the lid sealant adhesive, the lid and the container can be sealed.

[0055] Specific examples of the material of the plastic container include polyolefin resin, acrylic resin, polyamide resin, polyester resin, polycarbonate resin, polystyrene resin, styrene-acrylonitrile copolymer, and polyvinyl chloride resin.

[0056] Examples of polyolefin resins include low-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, and polypropylene.

[0057] Examples of the acrylic acid resin include polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, polyoctyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, and polyoctyl methacrylate.

[0058] Examples of polyamide resins include nylon 6, nylon 6,6, nylon 11, and nylon 12.

[0059] Examples of polyester resins include polyethylene terephthalate (amorphous polyethylene terephthalate, crystalline polyethylene terephthalate), polybutylene terephthalate, polylactic acid (including poly-L-lactic acid, poly-D-lactic acid, copolymers of L-lactic acid and D-lactic acid, and stereocomplexes of poly-L-lactic acid and poly-D-lactic acid), polybutylene succinate, poly(butylene succinate / adipate), polyethylene succinate, poly(butylene succinate / terephthalate), poly(butylene adipate / terephthalate), poly(hydroxybutyrate / hydroxyhexanoate), polyglycolic acid, poly(3-hydroxybutyrate), and polycaprolactone.

[0060] When the resin composition is used as an adhesive for adhering a plastic container containing these materials, the main component of the plastic container may be a single component or a composition of multiple resins. The container may also be a multi-layer laminate in which multiple materials are laminated.

[0061] The resin composition can be suitably used for containers made of polyethylene terephthalate, polystyrene, polypropylene, polyvinyl chloride, or polylactic acid.

[0062] The lid material according to one embodiment of the present invention will be described in detail below.

[0063] When the resin composition is used as an adhesive, it is preferably used as an adhesive layer containing the resin composition (hereinafter referred to as a "sealant adhesive layer").Furthermore, it can be suitably used as a lid material having a configuration including at least two layers, a supporting substrate layer and a sealant adhesive layer, with the sealant adhesive layer being the outermost layer.

[0064] The supporting substrate constituting the supporting substrate layer is not particularly limited as long as it has self-supporting properties, and examples thereof include olefin resins such as polyethylene, polypropylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, and saponified ethylene-vinyl acetate copolymer, polyethylene terephthalate, polybutylene terephthalate, polylactic acid (including poly-L-lactic acid, poly-D-lactic acid, copolymer of L-lactic acid and D-lactic acid, and stereocomplex of poly-L-lactic acid and poly-D-lactic acid), polybutylene succinate, poly(butylene succinate / adipate), polyethylene succinate, poly(butylene Examples of the support substrate layer include plastic films made of thermoplastic resins such as polyester resins such as poly(3-hydroxybutyrate / hydroxyhexanoate), poly(butylene adipate / terephthalate), poly(glycolic acid), poly(3-hydroxybutyrate), and polycaprolactone; polyamide resins such as nylon 6, nylon 6,6, nylon 11, and nylon 12; paper such as Japanese paper and composite paper; metal foil made of aluminum or other metal; vapor-deposited films in which aluminum, silica, or the like is vapor-deposited on the surface of a polyester resin film; and films formed solely or laminated with these. The thickness of the support substrate layer can be selected depending on the application as long as the mechanical strength, workability, and the like are not impaired, but is generally about 5 to 100 μm, and preferably 10 to 50 μm.

[0065] When used as a lid material, the thickness of the sealant adhesive layer can be selected depending on the application as long as the adhesiveness, workability, etc. are not impaired, but is generally about 5 to 50 μm, preferably 10 to 40 μm, and more preferably 15 to 30 μm.

[0066] The lid material may also include an intermediate layer between the support substrate layer and the sealant adhesive layer to enhance adhesion between the two layers. This intermediate layer may be composed of components such as thermoplastic resins such as polyolefins and thermoplastic elastomers, and these components may be used alone or in combination. Examples of polyolefins include polyethylene and ethylene copolymers (ethylene-α-olefin copolymers, propylene-ethylene copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-methyl acrylate copolymers, etc.), and modified products thereof. The intermediate layer may also contain various additives, such as antioxidants, lubricants, antistatic agents, conductive agents, antiblocking agents, and tackifiers, as long as they do not impair the effects of the present invention.

[0067] The thickness of the intermediate layer can be selected depending on the application as long as it does not impair workability, but is generally about 5 to 30 μm.

[0068] An anchor coat layer of polyurethane or the like can be provided between the supporting substrate layer and the sealant adhesive layer, or between the supporting substrate layer and the intermediate layer, in order to improve adhesion between the two layers.

[0069] A lid material having a sealant adhesive layer as the outermost layer is suitable as a lid material for various types of plastic containers, and combines high adhesive strength with transparency.

[0070] There are no particular restrictions on the method for producing the lid material, but examples include a method of laminating the sealant adhesive and the supporting substrate layer, and a method of co-extruding the sealant adhesive and the supporting substrate layer.

[0071] Examples of lamination methods include: (1) an extrusion lamination method in which an anchor coating agent is applied to a supporting substrate layer, and an adhesive layer is melt-extruded; (2) an extrusion lamination method in which an anchor coating agent is applied to a supporting substrate layer, and an intermediate layer is melt-extruded, and then a sealant adhesive layer is melt-extruded thereon; (3) an extrusion lamination method in which an intermediate layer having excellent adhesion to the supporting substrate, such as an ethylene-methacrylic acid copolymer or an ethylene-methyl methacrylate copolymer, is melt-extruded onto a supporting substrate layer, and then a sealant adhesive layer is melt-extruded thereon; (4) a co-extrusion lamination method in which an anchor coating agent is applied to a supporting substrate layer, and then the intermediate layer and adhesive layer are melt-extruded simultaneously; and (5) Examples of methods include a coextrusion lamination method in which an intermediate layer having excellent adhesion to the support substrate, such as an ethylene-methacrylic acid copolymer or an ethylene-methyl methacrylate copolymer, and a sealant adhesive layer are simultaneously melt-extruded onto the support substrate layer, (6) a dry lamination method in which a film containing at least one layer of sealant adhesive is formed in advance by inflation molding or cast molding, and then bonded to a support substrate layer coated with an anchor coating agent, and (7) a sandwich extrusion lamination method in which an intermediate layer is melt-extruded using extrusion lamination to laminate between a support substrate layer coated with an anchor coating agent and a film containing at least one layer of sealant adhesive.Meanwhile, examples of methods for coextruding the sealant adhesive and the support substrate layer include a coextrusion inflation method and a coextrusion T-die method.

[0072] The present invention will be explained in more detail below based on examples, but the present invention is not limited to these examples.

[0073] The adhesive strength, sealing strength and internal haze of the lid materials obtained in the examples were measured by the methods described below.

[0074] (Measurement of Adhesion Strength) The adhesive surface of the lid material was overlapped with a 0.35 mm thick A-PET sheet (manufactured by Toyobo Co., Ltd.), and pressure-heat bonded using a heat seal tester (manufactured by Tester Sangyo Co., Ltd., Model TP-701) under conditions of 160°C, 0.2 MPa, and 1 second. After cooling at room temperature, the adhesive strength was measured under conditions of a peel angle of 180° and a peel rate of 300 mm / min. The adhesive strength was also measured using the same method on a 0.35 mm thick silicone-coated A-PET sheet (manufactured by Mineron Kasei Co., Ltd.) whose surface was silicone-coated. The adhesive strength is preferably 10 N / 15 mm or more to prevent leakage of contents during transportation and storage.

[0075] (Measurement of Sealing Strength) The adhesive surface of the lid material was overlapped with an A-PET cup (manufactured by Rispack, diameter 101 mm, capacity 210 ml) and pressure-heated and bonded using a cup sealing machine (manufactured by Sunny Cup, model UF-500) under conditions of 160°C, 0.2 MPa, and 1 second. After cooling, the burst strength was measured using a seal tester (manufactured by Sun Scientific, model FKT-100J) under conditions of an air injection rate of 0.8 L / min. The strength obtained here is taken as the sealing strength. The sealing strength is preferably 10 kPa or more to prevent leakage of the contents during transportation and storage.

[0076] (Measurement of internal haze) The internal haze was measured by wetting the measurement points on the front and back surfaces of the lid material with liquid paraffin (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and sandwiching the material between two glass slides. The measurement was carried out in accordance with JIS K7136 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH7000 type). The internal haze is preferably 20% or less, as this ensures that the resulting packaging material using the lid material has excellent visibility of the contents.

[0077] Example 1 75 parts by weight of a resin (A1) (trade name Ultrathene (registered trademark) 537, manufactured by Tosoh Corporation) having a vinyl acetate content of 5.5% by weight and a melt mass-flow rate of 8.5 g / 10 min as the ethylene-vinyl acetate copolymer (A), 15 parts by weight of a fully hydrogenated petroleum resin (B1) (trade name Alcon (registered trademark) P125, manufactured by Arakawa Chemical Industries, Ltd.; softening temperature 125°C) as the tackifier resin (B), and 10 parts by weight of talc (C1) (trade name ImerFlex T20, manufactured by IMERYS) having an average particle size of 6 μm as the layered filler (CI) were pre-blended in a tumbler mixer, and then melt-kneaded at 160°C using a twin-screw extruder to obtain pellets of a resin composition.

[0078] Thereafter, a biaxially oriented polyester film (thickness 12 μm) serving as a support substrate layer was extrusion laminated with a low-density polyethylene intermediate layer (thickness 25 μm, manufactured by Tosoh Corporation, trade name Petrothene (registered trademark) 203). The resin composition pellets were extrusion laminated onto the low-density polyethylene surface of the resulting two-layer film using an extrusion laminator (manufactured by Sumitomo Heavy Industries Modern Co., Ltd., screw diameter 40 mmφ) at a processing temperature of 240°C to obtain a lid material with a resin composition layer thickness of 20 μm. The evaluation results of the obtained resin composition and the lid material are shown in Table 1.

[0079] Example 2 A resin composition and a lid material were obtained in the same manner as in Example 1, except that the ethylene-vinyl acetate copolymer (A1) was changed to 82 parts by weight, the tackifier resin (B1) to 15 parts by weight, and the layered filler (C1) to 3 parts by weight. The evaluation results of the obtained resin composition and lid material are shown in Table 1.

[0080] Example 3 A resin composition and a lid material were obtained in the same manner as in Example 1, except that 5 parts by weight of a thermoplastic block copolymer (D1) (Kraton (registered trademark) G1726VS) of a vinyl aromatic hydrocarbon and a diolefin, in which the mixing ratio of a hydrogenated styrene-butadiene diblock copolymer and a hydrogenated styrene-butadiene-styrene triblock copolymer was 7 / 3 and the styrene content was 30% by weight, was further blended into the resin composition consisting of the ethylene-vinyl acetate copolymer (A1), tackifier resin (B1), and layered filler (C1) of Example 1. The evaluation results of the obtained resin composition and the lid material are shown in Table 1.

[0081] Example 4 The resin composition of Example 3, which is composed of the ethylene-vinyl acetate copolymer (A1), the tackifier resin (B1), the layered filler (C1), and the compatibilizer (D1), was further mixed with an ethylene-α-olefin copolymer (E) having a density of 860 kg / m ３ A resin composition and a lid material were obtained in the same manner as in Example 3, except that 20 parts by weight of an ethylene-α-olefin copolymer (E1) (manufactured by Mitsui Chemicals, Inc., trade name: Tafmer (registered trademark) P-0375) was added. The evaluation results of the obtained resin composition and lid material are shown in Table 1.

[0082] Example 5 The resin composition of Example 3, which is composed of the ethylene-vinyl acetate copolymer (A1), the tackifier resin (B1), the layered filler (C1), and the compatibilizer (D1), was further mixed with a low-density polyethylene (F) having a density of 919 kg / m ３ A resin composition and a lid material were obtained in the same manner as in Example 3, except that 20 parts by weight of low-density polyethylene (F1) (manufactured by Tosoh Corporation, trade name Petrothene (registered trademark) 203) having a melt mass-flow rate of 8.0 g / 10 min and a melting point of 105°C was blended. The evaluation results of the obtained resin composition and lid material are shown in Table 1.

[0083] Example 6 A resin composition and a lid material were obtained in the same manner as in Example 3, except that 10 parts by weight of talc (C2) (trade name FH104, manufactured by Fuji Talc Industrial Co., Ltd.), a layered filler having an average particle size of 4 μm, was blended instead of the layered filler (C1).

[0084] Example 7 A resin composition and a lid material were obtained in the same manner as in Example 3, except that 10 parts by weight of talc (C3) (manufactured by Fuji Talc Industrial Co., Ltd., product name MG115), a layered filler having an average particle size of 14 μm, was blended in place of the layered filler (C1).

[0085] Example 8 A resin composition and a lid material were obtained in the same manner as in Example 3, except that 5 parts by weight of a thermoplastic block copolymer (D2) (Kraton (registered trademark) G1657VS) of a vinyl aromatic hydrocarbon and a diolefin, which had a styrene content of 13% by weight and a mixing ratio of a hydrogenated styrene-butadiene-diblock copolymer to a hydrogenated styrene-butadiene-styrene-triblock copolymer of 3 / 7, was blended in place of the compatibilizer (D1).

[0086] Comparative Example 1 A resin composition and a lid material were obtained in the same manner as in Example 1, except that the amount of ethylene-vinyl acetate copolymer (A1) was changed to 85 parts by weight and the amount of tackifier resin (B1) was changed to 15 parts by weight.

[0087] The evaluation results of the obtained resin composition and lid material are shown in Table 1. The obtained lid material was poor in adhesive strength and sealing strength.

[0088] Comparative Example 2 A resin composition and a lid material were obtained in the same manner as in Example 3, except that the ethylene-vinyl acetate copolymer (A1) was changed to 55 parts by weight, the tackifier resin (B1) to 15 parts by weight, the layered filler (C1) to 30 parts by weight, and the compatibilizer (D1) to 5 parts by weight.

[0089] The evaluation results of the obtained resin composition and lid material are shown in Table 1. The obtained lid material was poor in transparency.

[0090] Comparative Example 3 A resin composition and a lid material were obtained in the same manner as in Example 1, except that 10 parts by weight of aluminosilicate (C4) (manufactured by Mizusawa Industrial Chemicals, Ltd., trade name: Silton (registered trademark) JC-50), which is a non-layered filler having an average particle size of 5 μm, was blended in place of the layered filler (C1).

[0091] The evaluation results of the obtained resin composition and lid material are shown in Table 1. The obtained lid material had poor adhesive strength.

[0092] Comparative Example 4 A resin composition and a lid material were obtained in the same manner as in Example 1, except that 10 parts by weight of magnesium oxide (C5) (manufactured by Kyowa Chemical Industry Co., Ltd., trade name: Kyowamag 150), which is a non-layered filler having an average particle size of 6 μm, was blended in place of the layered filler (C1).

[0093] The evaluation results of the obtained resin composition and lid material are shown in Table 1. The obtained lid material was poor in adhesive strength, sealing strength, and transparency.

[0094]

[0095] Example 9 A resin composition and a lid material were obtained in the same manner as in Example 1, except that calcium carbonate (C6) (trade name: Viscoexcel 30, manufactured by Shiraishi Kogyo Co., Ltd.) having an average primary particle diameter of 0.03 μm was blended as the fine particles (CII) instead of the layered filler (CI). The evaluation results of the obtained resin composition and the lid material are shown in Table 2.

[0096] Example 10 A resin composition and a lid material were obtained in the same manner as in Example 9, except that the ethylene-vinyl acetate copolymer (A1) was changed to 82 parts by weight, the tackifier resin (B1) to 15 parts by weight, and the fine particles (C6) to 3 parts by weight. The evaluation results of the obtained resin composition and the lid material are shown in Table 2.

[0097] Example 11 A resin composition and a lid material were obtained in the same manner as in Example 9, except that 5 parts by weight of a compatibilizer (D1) was further blended into the resin composition consisting of the ethylene-vinyl acetate copolymer (A1), tackifier resin (B1), and fine particles (C6) of Example 9. The evaluation results of the obtained resin composition and lid material are shown in Table 2.

[0098] Example 12 A resin composition and a lid material were obtained in the same manner as in Example 11, except that 10 parts by weight of calcium carbonate (C7) (manufactured by Shiraishi Kogyo Co., Ltd., trade name CALSHITEC (registered trademark) Vigot 15) having an average primary particle diameter of 0.15 μm was blended in place of the fine particles (C6). The evaluation results of the obtained resin composition and lid material are shown in Table 2.

[0099] Example 13 A resin composition and a lid material were obtained in the same manner as in Example 11, except that 20 parts by weight of ethylene-α-olefin copolymer (E1) was further blended into the resin composition consisting of ethylene-vinyl acetate copolymer (A1), tackifier resin (B1), fine particles (C6), and compatibilizer (D1) of Example 11. The evaluation results of the obtained resin composition and lid material are shown in Table 2.

[0100] Example 14 A resin composition and a lid material were obtained in the same manner as in Example 11, except that 20 parts by weight of low-density polyethylene (F1) was further blended into the resin composition consisting of the ethylene-vinyl acetate copolymer (A1), tackifier resin (B1), fine particles (C6), and compatibilizer (D1) of Example 11. The evaluation results of the obtained resin composition and lid material are shown in Table 2.

[0101] Example 15 A resin composition and a lid material were obtained in the same manner as in Example 11, except that 5 parts by weight of a thermoplastic block copolymer (D2) (Kraton (registered trademark) G1657VS) of a vinyl aromatic hydrocarbon and a diolefin, which had a styrene content of 13% by weight and a mixing ratio of a hydrogenated styrene-butadiene-diblock copolymer to a hydrogenated styrene-butadiene-styrene-triblock copolymer of 3 / 7, was blended in place of the compatibilizer (D1).

[0102] Comparative Example 5 A resin composition and a lid material were obtained in the same manner as in Example 9, except that the amount of ethylene-vinyl acetate copolymer (A1) was changed to 85 parts by weight and the amount of tackifier resin (B1) was changed to 15 parts by weight.

[0103] The evaluation results of the obtained resin composition and lid material are shown in Table 2. The obtained lid material was poor in adhesive strength and sealing strength.

[0104] Comparative Example 6 A resin composition and a lid material were obtained in the same manner as in Example 11, except that the ethylene-vinyl acetate copolymer (A1) was changed to 55 parts by weight, the tackifier resin (B1) to 15 parts by weight, the fine particles (C6) to 30 parts by weight, and the compatibilizer (D1) to 5 parts by weight.

[0105] The evaluation results of the obtained resin composition and lid material are shown in Table 2. The obtained lid material was poor in transparency.

[0106] Comparative Example 7 A resin composition and a lid material were obtained in the same manner as in Example 9, except that 10 parts by weight of calcium carbonate (C8) (manufactured by Shiraishi Kogyo Co., Ltd., trade name Whiten (registered trademark) P30) having an average primary particle diameter of 4 μm was blended in place of the fine particles (C6). The evaluation results of the obtained resin composition and lid material are shown in Table 2. The obtained lid material was poor in adhesive strength, sealing strength, and transparency.

[0107]

[0108] While the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

[0109] The entire contents of the specifications, claims and abstracts of Japanese Patent Applications No. 2024-031101 and 2024-031102 filed on March 1, 2024 are hereby cited and incorporated as the disclosure of the specification of the present invention.

Claims

1. A resin composition comprising 50 to 94.5 parts by weight of an ethylene-vinyl acetate copolymer (A), 5 to 30 parts by weight of a tackifier resin (B), and 0.5 to 25 parts by weight of a layered filler (CI) or fine particles (CII) having an average primary particle diameter in the range of 0.001 to 1 μm (wherein the total of (A), (B), (CI), and (CII) is 100 parts by weight).

2. The resin composition according to claim 1, further comprising 0.5 to 20 parts by weight of a compatibilizer (D) per 100 parts by weight of the resin composition.

3. The resin composition according to claim 2, wherein the compatibilizer (D) is a hydrogenated polystyrene-polybutadiene-polystyrene block copolymer and has a styrene content of 5 to 20% by weight.

4. For 100 parts by weight of the resin composition, the density measured according to JIS K6922-1 is 860 to 910 kg / m ３ 2. The resin composition according to claim 1, comprising 5 to 100 parts by weight of an ethylene / α-olefin copolymer (E) in the range of:

5. For 100 parts by weight of the resin composition, the density measured according to JIS K6922-1 is 910 to 940 kg / m ３ and 5 to 100 parts by weight of a low-density polyethylene (F) having a melting point in the range of 98 to 120°C as measured according to JIS K6924-2.

6. The resin composition according to claim 1, wherein the tackifier resin (B) is at least one selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, alicyclic hydrogenated petroleum resins, and copolymer petroleum resins.

7. The resin composition according to claim 1, wherein the layered filler (CI) is talc.

8. The resin composition according to claim 1, wherein the fine particles (CII) are calcium carbonate.

9. A sealant adhesive comprising the resin composition according to any one of claims 1 to 8.

10. The sealant adhesive according to claim 9, which is for a container made of at least one resin selected from the group consisting of polyethylene terephthalate, polystyrene, polypropylene, polyvinyl chloride, and polylactic acid.

11. A lid material comprising at least two layers: a layer containing the resin composition according to any one of claims 1 to 8, and a supporting substrate layer.

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