Aqueous heat-sealing agent for cables, heat-sealing film for cables, and cable using same

Abstract

The following are provided: an aqueous heat-sealing agent for cables that contains an aqueous medium and a resin comprising an ethylene-vinyl acetate copolymer or a polyester resin; a heat-sealing film for cables in which this heat-sealing agent for cables is disposed on a base material; and a cable that uses the heat-sealing film for cables in which the aqueous heat-sealing agent for cables is disposed on a base material. By using the aqueous heat-sealing agent for cables, energy savings can be achieved as compared to the use of hot-melt adhesives and the environmental load is reduced.

Description

Water-based heat sealant for cables, heat seal film for cables, and cables using the same

[0001] This invention relates to an aqueous heat sealant for cables, a heat seal film for cables, and a cable using the same.

[0002] Electrical cables consist of insulated wires, which are made by covering a conductor such as copper or aluminum with an insulator such as a plastic film, and then applying a sheath (outer covering) to these insulated wires or strands of them. Adhesives are used when applying the insulator and sheath, and hot melt adhesives are mainly used as the type of adhesive (see Patent Document 1).

[0003] However, hot melt adhesives require a significant amount of thermal energy during application, as they involve applying heat of around 250 degrees Celsius to melt the thermoplastic resin, which is the main component of the adhesive. Due to the recent rise in energy costs, there is a growing movement to move away from hot melt adhesives. Furthermore, while the thermoplastic resin is melted into a liquid state by applying heat, then cooled and solidified to create a bond, it softens and peels off when heated again, resulting in problems with heat resistance, durability, and even water resistance. In addition, using hot melt adhesives requires specialized application equipment, which is disadvantageous in terms of maintenance costs.

[0004] In this context, heat-sealing agents that can be applied using general-purpose gravure coating machines are beginning to attract attention.

[0005] On the other hand, heat sealants come in two types: those that use organic solvents and those that use aqueous solvents with water as the main component. In the case of heat sealants, there is a strong demand for coating solutions that use aqueous solvents from the perspective of reducing environmental impact.

[0006] Patent No. 7014345

[0007] By replacing the conventional hot-melt adhesive used for cables with a newly developed water-based heat sealant suitable for cables, the need to apply the thermal energy required to melt the resin in conventional hot-melt adhesives is eliminated, resulting in energy savings. Furthermore, using a water-based heat sealant is expected to prevent the resin from softening even when heat is applied again, thus preventing peeling.

[0008] However, there is no global track record of using water-based solvents in heat sealants for electric wire and cable applications, where high quality requirements and long-term stability are demanded. No heat sealants using water-based solvents suitable for cable applications are currently known.

[0009] Heat sealants used in packaging materials and other applications are applied to a base material such as film or paper, and then heat is applied using a machine such as a heat sealer to bond them together. In contrast, when using heat sealants for cables, it is necessary to wrap a tape-shaped film coated with the heat sealant around a linear cable and then apply heat to bond it. In other words, a general heat sealer cannot be used for cables, and because a gap exists between the heat source and the heat sealant during heat sealing, the heat sealing temperature is lower than the actual temperature of the heat source. Furthermore, it is not possible to heat seal under high pressure during wrapping. Therefore, there is a need for a heat sealant that can achieve high heat sealing performance while wrapped around a cable.

[0010] Therefore, the problem that the present invention aims to solve is to provide a heat sealant for cables that uses an aqueous medium, which can achieve energy savings compared to using hot melt adhesives and reduces environmental impact.

[0011] In other words, the present invention is an aqueous heat sealant for cables, comprising a resin containing an ethylene vinyl acetate copolymer or polyester resin, and an aqueous medium.

[0012] Furthermore, the present invention relates to a heat-sealable cable film comprising an aqueous heat-sealing agent for cables, provided on a substrate, which contains an ethylene vinyl acetate copolymer or a resin containing a polyester resin and an aqueous medium.

[0013] Furthermore, the present invention relates to a cable using a heat-sealable film for cables, wherein an aqueous heat-sealing agent for cables, comprising an ethylene vinyl acetate copolymer or a resin containing a polyester resin and an aqueous medium, is provided on a substrate.

[0014] The water-based heat sealant for cables of the present invention can achieve energy savings compared to the use of hot-melt adhesives, thereby reducing the environmental impact. Furthermore, because the water-based heat sealant can be manufactured using a general gravure coating machine, equipment maintenance is easy, and since the heat sealant uses an aqueous medium, an environmentally friendly heat sealant can be provided.

[0015] Figure 1 is a schematic diagram showing the arrangement of the laminate in the overhang evaluation test.

[0016] <Heat sealant> The heat sealant of the present invention contains a resin containing ethylene vinyl acetate copolymer or polyester resin, and an aqueous medium.

[0017] [First Embodiment] The heat sealant in the first embodiment contains a resin containing an ethylene vinyl acetate copolymer.

[0018] (Ethylene-vinyl acetate copolymer resin) The ethylene-vinyl acetate copolymer resin is a copolymer obtained by copolymerizing ethylene and vinyl acetate, and in some cases the ester portion may be partially or completely hydrolyzed. In addition, the ethylene-vinyl acetate copolymer resin may be further copolymerized with other monomers, but the content of constituent units derived from other monomers is preferably 30% by mass or less, more preferably 10% by mass or less, even more preferably 3% by mass or less, and even more preferably 1% by mass or less of the total copolymer.

[0019] From the viewpoint of stability of heat seal strength and blocking resistance in the low-temperature range of approximately 80°C to 100°C, it is preferable that the proportion of ethylene in the copolymer is 45 mol% or less. Preferably, it is 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less. On the other hand, from the viewpoint of blocking resistance, it is preferable that the proportion of vinyl acetate in the copolymer is 5 mol% or more, more preferably 10 mol% or more.

[0020] The weight-average molecular weight of the ethylene-vinyl acetate copolymer resin is not particularly limited, but from the viewpoint of blocking resistance, it is preferably 200,000 or more. On the other hand, from the viewpoint of low-temperature heat sealability, the weight-average molecular weight is preferably 1,000,000 or less.

[0021] Furthermore, the glass transition temperature of the ethylene-vinyl acetate copolymer is not particularly limited, but when low-temperature sealing is required, it is preferably 30°C or lower, more preferably 20°C or lower, and even more preferably 10°C or lower. When high-temperature sealing is required, the Tg is 30°C or higher, preferably 35°C or higher.

[0022] The glass transition temperature of an ethylene-vinyl acetate copolymer is the value measured as follows.

[0023] Using a differential scanning calorimetry system (DSC-7000, manufactured by SII Nanotechnology Co., Ltd., hereinafter referred to as DSC), 5 mg of the sample is heated from room temperature to 200°C at a rate of 10°C / min under a nitrogen stream of 30 mL / min, and then cooled to -80°C at a rate of 10°C / min. The sample is then heated again to 150°C at a rate of 10°C / min, and the DSC curve is measured. The glass transition point is defined as the intersection of a straight line extending from the low-temperature baseline of the measurement results observed in the second heating step to the high-temperature side, and a tangent line drawn at the point where the slope of the curve of the step-like portion of the glass transition is maximum. The temperature at this point is defined as the glass transition temperature. In addition, the temperature is raised to 200°C in the first heating step, but this is sufficient as long as it is a temperature at which the ethylene-vinyl acetate copolymer is sufficiently melted, and if 200°C is insufficient, it should be adjusted as appropriate. Similarly, if the cooling temperature of -80°C is insufficient (for example, if the glass transition temperature is lower), it should be adjusted as appropriate.

[0024] (Other resins) In the heat sealant of the first embodiment, the resin may consist only of an ethylene-vinyl acetate copolymer resin, but it may also contain an ethylene-vinyl acetate copolymer resin and other resins. Preferably, the other resins include (meth)acrylic resins and polyolefin resins.

[0025] ((meth)acrylic resin) In the present invention, (meth)acrylic resin refers to a homopolymer or copolymer of (meth)acrylate, (meth)acrylate refers to the general term for acrylate and methacrylate, and (meth)acrylic acid refers to the general term for acrylic acid and methacrylic acid.

[0026] In this invention, a homopolymer or copolymer of (meth)acrylate can be used as the (meth)acrylic resin. There are no particular limitations on the homopolymer or copolymer of (meth)acrylate, and examples of copolymers include copolymers obtained by copolymerizing (meth)acrylate with a vinyl monomer that can copolymerize. Furthermore, it is preferable that the copolymer has an acid value in order to impart water dispersibility and water solubility.

[0027] There are no particular limitations on the (meth)acrylate used as a component of a homopolymer or copolymer of (meth)acrylate, but it is preferably an acrylate having an alkyl group having 1 to 20 carbon atoms, as homopolymers having acrylate exhibit a lower glass transition temperature, and it is preferable that the main component be an acrylate having an alkyl group having 1 to 20 carbon atoms, and it is preferable that the main component be an acrylate having an alkyl group having 4 to 15 carbon atoms. Examples of such acrylates having an alkyl group having 1 to 15 carbon atoms include methyl acrylate, ethyl acrylate, isopropyl acrylate, allyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl (meth)acrylate, tert-butyl acrylate, n-amyl acrylate, iso-amyl acrylate, n-hexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-dodecyl (meth)acrylate, and n-tridecyl (meth)acrylate. The (meth)acrylate used as a component of the aqueous heat sealant of the present invention may be one type or two or more types, but it is preferable to use two or more types of (meth)acrylate, and in particular it is preferable to use two or more types of acrylate having alkyl groups with 4 to 15 carbon atoms.

[0028] Furthermore, examples of vinyl monomers that can copolymerize with other (meth)acrylates include aromatic (meth)acrylates such as benzyl (meth)acrylate; hydroxyl group-containing monomers such as 2-hydrodoxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; alkyl polyalkylene glycol mono(meth)acrylates such as methoxypolyethylene glycol mono(meth)acrylate and methoxypolypropylene glycol mono(meth)acrylate; and perfluoroalkylethyl (meth)acrylate, etc. Fluorine-based (meth)acrylates; styrene, styrene derivatives (p-dimethylsilylstyrene, (p-vinylphenyl)methyl sulfide, p-hexynylstyrene, p-methoxystyrene, p-tert-butyldimethylsiloxystyrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, α-methylstyrene, etc.), vinylnaphthalene, vinylanthracene, 1,1-diphenylethylene, and other aromatic vinyl compounds; glycidyl (meth)acrylate, epoxy (meth)acrylate, ethylene glycol di(meth)acrylate Acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylene glycol tetra(meth)acrylate, 2-hydroxy-1,3-diacroxypropane, 2,2-bis[4-(acryloxymethoxy)phenyl]propane, 2,2-bis[4-(acryloxyethoxy)phenyl]propane, dicyclopentenyl(meth)acrylate, tricyclodecanyl(meth)acrylate, tris(acryloxyethyl)isocyanurate, urethane(meth)acrylate Examples include (meth)acrylate compounds such as: alkylamino group-containing (meth)acrylates such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and dimethylaminopropyl (meth)acrylate; vinylpyridine compounds such as 2-vinylpyridine, 4-vinylpyridine, and naphthylvinylpyridine; and conjugated dienes such as 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and 1,3-cyclohexadiene.These monomers can be used individually or in combination of two or more.

[0029] Furthermore, with the aim of introducing one or more acidic groups selected from the group consisting of carboxyl groups and carboxylate groups obtained by neutralizing a carboxyl group with a basic compound, copolymers having an acid value can be obtained by copolymerizing (meth)acrylic monomers having carboxyl groups, such as (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, β-(meth)acryloyloxyethyl hydrogen succinate, and β-(meth)acryloyloxyethyl hydrogen phthalate. When introducing an acidic group, it is preferable to appropriately adjust the amount of monomer so that the acid value falls within the desired range.

[0030] The meth(acrylic) resin used in the aqueous heat sealant of the present invention is preferably a copolymer of (meth)acrylic acid and the (meth)acrylate. For example, it is preferably a copolymer of (meth)acrylic acid and an acrylate having an alkyl group with 4 to 15 carbon atoms, such as n-butyl (meth)acrylate, n-dodecyl (meth)acrylate, or n-tridecyl (meth)acrylate.

[0031] (Meth)acrylate homopolymers or copolymers can be produced, for example, by polymerizing one or more monomers in the presence of a polymerization initiator in a temperature range of 50°C to 180°C, with a temperature range of 80°C to 150°C being more preferable. Examples of polymerization methods include bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Examples of polymerization modes include random copolymers, block copolymers, and graft copolymers. The copolymer may also be of the core-shell type.

[0032] Other resins besides (meth)acrylic resins include, for example, vinyl chloride resins, styrene resins, styrene / butadiene copolymers, styrene / unsaturated carboxylic acid copolymers, acrylonitrile / styrene copolymers, acrylonitrile / butadiene copolymers, ABS resins, AAS resins, AES resins, vinylidene chloride resins, polyurethane resins, poly-4-methylpentene-1 resins, polybutene-1 resins, vinylidene fluoride resins, vinyl fluoride resins, fluorine resins, polycarbonate resins, polyamide resins, acetal resins, polyphenylene oxide resins, polyester resins (polyethylene terephthalate, polybutylene terephthalate, etc.), polyphenylene sulfide resins, polyimide resins, polysulfone resins, polyethersulfone resins, polyarylate resins, olefin / unsaturated carboxylic acid copolymers, and modified versions thereof. These may be used individually or in combination of two or more.

[0033] (Polyolefin resin) The composition of the polyolefin resin is not particularly limited, but examples include amorphous polyolefins which are homopolymers, binary copolymers, or polypolymers selected from ethylene, propylene, and α-olefins having 4 to 8 carbon atoms. Specific examples include amorphous polyolefins mainly composed of propylene or 1-butene components, such as propylene homopolymers, propylene-ethylene copolymers, propylene-1-butene copolymers, 1-butene-ethylene copolymers, propylene-1-hexene copolymers, propylene-4-methyl-1-pentene copolymers, 1-butene-1-hexene copolymers, propylene-ethylene-1-butene terpolymers, propylene-ethylene-1-hexene terpolymers, propylene-ethylene-4-methyl-1-pentene terpolymers, propylene-1-butene-1-hexene terpolymers, propylene-1-hexene-1-octene terpolymers, and propylene-1-hexene-4-methyl-1-pentene terpolymers.

[0034] It is preferable to use a polyolefin resin that has been acid-modified by bonding carboxyl groups (or their acid anhydrides) to the polyolefin resin using an unsaturated carboxylic acid and an organic peroxide. Examples of unsaturated carboxylic acids include (meth)acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, nadic acid (trade name, endosis-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic acid), maleic anhydride, itaconic anhydride, and citraconic anhydride. The amount of unsaturated carboxylic acid used is preferably 0.5 to 50 parts by weight, and more preferably 1 to 25 parts by weight, per 100 parts by weight of the polyolefin resin.

[0035] In the first embodiment, it is preferable that the solid content concentration of the ethylene-vinyl acetate copolymer resin in the entire resin component contained in the heat sealant is 30% by mass or more. Furthermore, from the viewpoint of achieving both sealing performance and adhesion to the substrate, it is preferable to use ethylene-vinyl acetate copolymer resin in combination with another resin such as (meth)acrylic resin or polyolefin resin in the heat sealant. When using ethylene-vinyl acetate copolymer resin in combination with (meth)acrylic resin or polyolefin resin, in order to obtain the effects of the present invention, the solid content concentration of these resin components is preferably adjusted to 60% by mass or more in the entire resin component, more preferably to 70% by mass or more, and even more preferably to 80% by mass or more.

[0036] Furthermore, the ratio of solid content concentrations between the ethylene-vinyl acetate copolymer resin and the (meth)acrylic resin is preferably (ethylene-vinyl acetate copolymer resin):((meth)acrylic resin) = 90:10 to 10:90, and more preferably 70:30 to 30:70.

[0037] Furthermore, the ratio of solid content concentrations between the ethylene-vinyl acetate copolymer resin and the polyolefin resin is preferably (ethylene-vinyl acetate copolymer resin):polyolefin resin = 99:1 to 10:90, and more preferably 90:10 to 30:70.

[0038] (Aqueous Medium) As the aqueous medium, water, water-soluble organic solvents dissolved in water, etc. can be used. As the water, pure water such as ion-exchanged water, ultrafiltration water, reverse osmosis water, distilled water, or ultrapure water can be used. From the perspective of long-term storage, it is preferable to use water sterilized by ultraviolet irradiation or hydrogen peroxide addition, etc. because it can prevent the generation of mold or bacteria.

[0039] As the water-soluble organic solvent, for example, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol; diols such as butanediol, pentanediol, hexanediol; glycol esters such as propylene glycol laurate; diethylene glycol ethers such as diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl, carbitol; glycol ethers such as cellosolve including propylene glycol ether, dipropylene glycol ether, and triethylene glycol ether; alcohols such as methanol, ethanol, isopropyl alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, butyl alcohol, pentyl alcohol; lactones such as sulfolane, ester, ketone, γ-butyrolactone; lactams such as N-(2-hydroxyethyl)pyrrolidone; glycerin and its polyalkylene oxide adducts, and various other solvents known as water-soluble organic solvents can be mentioned. These water-soluble organic solvents can be used alone or in combination of two or more. It is preferable to use water, and it is preferable to use water as the main component. However, when the wettability to the substrate is insufficient with only water, it is preferable to use water and alcohol in combination. As the alcohol, ethanol and isopropyl alcohol are preferable.

[0040] When water and a water-soluble organic solvent are used in combination, the ratio is preferably such that the proportion of water in the aqueous medium is 70% by mass or more, and more preferably 80% by mass or more.

[0041] (Additives) In the first embodiment, the heat-sealing agent may contain additives such as antiblocking agents, defoaming agents, viscosity modifiers, leveling agents, tackifiers, preservatives, antibacterial agents, rust inhibitors, antioxidants, silicone oils, lubricants, antistatic agents, ultraviolet absorbers, crosslinking agents, etc. in addition to the resin component as long as the object of the present invention is not inhibited.

[0042] As lubricants, fatty acid amide waxes such as oleic acid amide, erucic acid amide, stearic acid amide, behenic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, rice wax, carnauba wax, candelilla wax, lanolin wax, beeswax, whale oil, beef tallow and other animal and vegetable oil waxes, petrolatum, paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, PTFE wax, linear higher alcohols and other petroleum waxes, dimethylpolysiloxane, modified silicone such as modified dimethylpolysiloxane in which at least one of the methyl groups in the side chain is substituted with an organic group other than a methyl group (carbinol group, polyether group, alkyl group having 2 or more carbon atoms, etc.). The addition amount of the lubricant is preferably 0.1 to 2% by weight based on the total heat-sealing agent because it can impart lubricity and the balance with other properties is good. Also, it is preferably 2 to 5% by weight based on the modified polyolefin because it facilitates the handling of the heat-sealing film coated with the heat-sealing agent.

[0043] (Defoaming Agent) In the aqueous heat-sealing agent, it is preferable to contain a defoaming agent to prevent foaming when coating using various coaters. As the defoaming agent, nonionic defoaming agents, silicone-based defoaming agents, and fluorine-based defoaming agents are preferably used. Any of these defoaming agents, such as emulsion dispersion type and solubilization type, can be used. Among them, nonionic defoaming agents are preferred. The addition amount of the defoaming agent is preferably in the range of 0.005% by mass or more and 3% by mass or less, more preferably in the range of 0.1% by mass or more and 1% by mass or less, based on the total amount of the aqueous heat-sealing agent.

[0044] (Blocking Prevention) While the aqueous heat sealant for cables of the present invention exhibits good heat sealability at low temperatures, it tends to have poor blocking properties. Therefore, it is preferable to include a blocking prevention agent.

[0045] It is preferable to use inorganic fine particles, organic fine particles, etc., as the blocking inhibitor.

[0046] Examples of organic fine particles include polystyrene-based and polymethacrylate-based organic polymer fine particles. Among these, polymethacrylate-based organic polymer fine particles are preferred because they can enhance blocking properties while maintaining heat-sealability, and cross-linked polymethyl methacrylate is preferred.

[0047] As the inorganic fine particles, silica is preferred, and synthetic amorphous silica is preferred in particular. The shape of the silica is not particularly limited, and may be, for example, spherical silica consisting of a single particle, or amorphous silica forming secondary and tertiary particles from a plurality of primary particles. Spherical silica is preferred in particular.

[0048] Examples of spherical silica include AdmaFine SO-C4, SO-C5, and SO-E4 from Admatex Corporation, UFP-30 and SFP-30M from Denka Corporation, SeaHostar KE series from Nippon Shokubai Corporation, and SYLOSPHERE series from Fuji Silicia Corporation. Examples of amorphous silica include AEROSIL200 and R972 from EVONIK Corporation, HDK H15 and H18 from Asahi Kasei Wacker Silicone Corporation, and MT-10 and DM20S from Tokuyama Corporation.

[0049] From the viewpoint of achieving both blocking properties and heat-sealing properties, the average particle size of the blocking inhibitor is preferably 0.1 μm to 20 μm, more preferably 0.5 μm to 15 μm, and even more preferably 1.0 μm to 10 μm.

[0050] The amount of the blocking inhibitor added is preferably in the range of 0.1% by mass or more and 2% by mass or less relative to the total amount of the aqueous heat sealant.

[0051] (Crosslinking agent (curing agent)) Water-based heat sealants preferably contain a crosslinking agent. By including a crosslinking agent (curing agent), the heat seal strength, heat resistance, etc. can be further enhanced. In cable applications, since they are often used under high-temperature conditions, it is preferable to include a crosslinking agent (curing agent) to provide excellent durability (heat resistance). In cable applications, as mentioned above, a tape-shaped film coated with a heat sealant is wrapped around a linear cable, so if the durability (heat resistance) is weak, the coated heat seal layer is likely to ooze out. However, by including a crosslinking agent (curing agent), heat resistance can be enhanced and the oozing of the heat seal layer can be suppressed.

[0052] The crosslinking agent (curing agent) is not particularly limited, but known materials such as polyisocyanate compounds, silane coupling agents, epoxy compounds, carbodiimides, aziridines, oxazoline compounds, and metal chelating agents can be used. In particular, from the viewpoint of providing excellent high durability (heat resistance), it is preferable to use an isocyanate-based curing agent using a polyisocyanate compound or a carbodiimide-based curing agent using a polycarbodiimide compound.

[0053] The polyisocyanate compound is not particularly limited, as long as it is an isocyanate compound having multiple isocyanate groups that can react with the resin in the heat sealant. Examples include polyisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), lysine diisocyanate, trimethylhexamethylene diisocyanate, 1,3-(isocyanatemethyl)cyclohexane, 1,5-naphthalene diisocyanate, and triphenylmethane triisocyanate; and derivatives (modified products) of polyisocyanates such as adducts of these polyisocyanates, burettes of these polyisocyanates, or isocyanurates of these polyisocyanates.

[0054] Polyisocyanate compounds act as curing agents and can be selected and used as appropriate, and may be aromatic or aliphatic. Preferred polyisocyanate compounds include, for example, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), tolylene diisocyanate (TDI), and diphenylmethane diisocyanate (MDI). Among these, xylylene diisocyanate (XDI) and tolylene diisocyanate (TDI) are preferred. Carbodiimide curing agents are not particularly limited as long as they are compounds having at least one carbodiimide group (-N=C=N-). As carbodiimide curing agents, polycarbodiimide compounds having at least two or more carbodiimide groups are preferred.

[0055] The silane coupling agent is a silane compound having one or more hydrolyzable groups and one or more organic polymerizable functional groups in one molecule. Examples of the hydrolyzable groups include alkoxy groups such as methoxy groups and ethoxy groups; acyloxy groups such as acetoxy groups; and halogen groups such as chloro groups. Examples of the organic polymerizable functional groups include vinyl groups, epoxy groups, methacryloxy groups, acryloxy groups, amino groups, mercapto groups, isocyanate groups, ureido groups, and isocyanurate groups. The silane coupling agent may contain one or more of these hydrolyzable groups and one or more of these organic polymerizable functional groups in one or more molecules.

[0056] Examples of the silane coupling agents include vinyl group-containing silane coupling agents (silane compounds having vinyl group and hydrolyzable group), epoxy group-containing silane coupling agents (silane compounds having epoxy group and hydrolyzable group), (meth)acryloxy group-containing silane coupling agents (silane compounds having (meth)acryloxy group and hydrolyzable group), amino group-containing silane coupling agents (silane compounds having amino group and hydrolyzable group), mercapto group-containing silane coupling agents (silane compounds having mercapto group and hydrolyzable group), isocyanate group-containing silane coupling agents (silane compounds having isocyanate group and hydrolyzable group), ureido group-containing silane coupling agents (silane compounds having ureido group and hydrolyzable group), and isocyanurate group-containing silane coupling agents (silane compounds having isocyanurate group and hydrolyzable group).

[0057] Examples of silane coupling agents having a vinyl group include vinyltrimethoxysilane, vinyltriethoxysilane, and p-styryltrimethoxysilane.

[0058] Examples of silane coupling agents having the epoxy group include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane.

[0059] Examples of the silane coupling agent having a (meth)acryloxy group include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane.

[0060] Examples of silane coupling agents having an amino group include compounds having one hydrocarbon group with one amino group in the molecule and one or more hydrolyzable groups in the molecule, such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-3-aminopropyltrimethoxysilane; and compounds having one hydrocarbon group with two amino groups in the molecule and one or more hydrolyzable groups in the molecule, such as N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane.

[0061] Examples of silane coupling agents having a mercapto group include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane.

[0062] Examples of silane coupling agents having an isocyanate group include 3-isocyanatetopropyltriethoxysilane.

[0063] Examples of silane coupling agents having a ureido group include 3-ureidopropyltrimethoxysilane and 3-ureidopropyltriethoxysilane.

[0064] Examples of silane coupling agents having an isocyanurate group include tris-(trimethoxysilylpropyl)isocyanurate.

[0065] These crosslinking agents are preferably present in an amount of 0.1 to 30% by mass relative to the solid content of the aqueous heat sealant of the present invention, and more preferably in an amount of 0.5 to 15% by mass. When an isocyanate-based curing agent or a carbodiimide-based curing agent is used, it is preferably present in an amount of 0.1 to 15% by mass, more preferably in an amount of 0.5 to 10% by mass, and even more preferably in an amount of 1 to 5% by mass.

[0066] In the aqueous heat sealant according to the first embodiment, it is preferable to adjust the solid content concentration of the resin component to 20 to 70% by mass.

[0067] The acid value of the aqueous heat sealant is preferably 5 mg / KOH or more and 15 mg / KOH or less. If it is 5 mg / KOH or more, the solubility in water can be improved. On the other hand, if it is 15 mg / KOH or less, the dispersion state in water can be stabilized. Preferably, it is in the range of 7 mg / KOH or more and 12 mg / KOH or less, and more preferably in the range of 8 mg / KOH or more and 10 mg / KOH or less.

[0068] [Second Embodiment] The heat sealant in the second embodiment contains a resin mainly composed of polyester resin.

[0069] (Polyester resin) Polyester resin is a reaction product of polycarboxylic acid and polyhydric alcohol.

[0070] Polycarboxylic acids used in the synthesis of polyester resins can be any conventionally known type without particular limitation, such as malonic acid, ethyl malonic acid, dimethyl malonic acid, succinic acid, 2,2-dimethyl succinic acid, succinic anhydride, alkenyl succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, maleic anhydride, and itaconic acid; alkyl esters of aliphatic polybasic acids such as dimethyl malonate, diethyl malonate, dimethyl succinate, dimethyl glutarate, dimethyl adipic acid, diethyl pimelic acid, diethyl sebacate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, and diethyl maleate; Alicyclic polybasic acids such as 1,1-cyclopentanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride, hymic anhydride, and hetic anhydride; Aromatic polybasic acids such as orthophthalic acid, terephthalic acid, isophthalic acid, phthalic anhydride, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid anhydride, naphthalic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, benzophenonetetracarboxylic acid, benzophenonetetracarboxylic acid dianhydride, 5-sodium sulfoisophthalic acid, tetrachlorophthalic anhydride, and tetrabromophthalic anhydride; methyl esters of aromatic polybasic acids such as dimethylterephthalic acid and dimethyl 2,6-naphthalenedicarboxylic acid; and one or more of these can be used in combination.

[0071] The polyhydric alcohols used in the synthesis of polyester resins can be conventionally known ones without particular limitation, such as aliphatic diols like ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,2,2-trimethyl-1,3-propanediol, 2,2-dimethyl-3-isopropyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,4-bis(hydroxymethyl)cyclohesane, 2,2,4-trimethyl-1,3-pentanediol; and ether glycols such as polyoxyethylene glycol and polyoxypropylene glycol. Examples include: modified polyether diols obtained by ring-opening polymerization of the aliphatic diol with various cyclic ether bond-containing compounds such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and allyl glycidyl ether; lactone-based polyester polyols obtained by polycondensation reaction of the aliphatic diol with various lactones such as lactanoides and ε-caprolactone; bisphenols such as bisphenol A and bisphenol F; and alkylene oxide adducts of bisphenols obtained by adding ethylene oxide, propylene oxide, etc., to bisphenols such as bisphenol A and bisphenol F.

[0072] Polyols with three or more functions may be used as the polyhydric alcohol, including aliphatic polyols such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol, and pentaerythritol; modified polyether polyols obtained by ring-opening polymerization of the aliphatic polyol with various cyclic ether bond-containing compounds such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and allyl glycidyl ether; and lactone-based polyester polyols obtained by polycondensation reaction of the aliphatic polyol with various lactones such as ε-caprolactone.

[0073] Regarding the glass transition temperature (Tg) of polyester resin, when low-temperature sealing performance is required, the Tg is preferably 50°C or lower, more preferably 40°C or lower, and even more preferably 30°C or lower. When high-temperature sealing performance is required, the Tg is 50°C or higher, preferably 60°C or higher.

[0074] The glass transition temperature of polyester is the value measured as follows.

[0075] Using a differential scanning calorimetry system (DSC-7000, manufactured by SII Nanotechnology Co., Ltd., hereinafter referred to as DSC), 5 mg of the sample is heated from room temperature to 200°C at a rate of 10°C / min under a nitrogen stream of 30 mL / min, and then cooled to -80°C at a rate of 10°C / min. The sample is then heated again to 150°C at a rate of 10°C / min, and the DSC curve is measured. The glass transition point is defined as the intersection of a straight line extending from the low-temperature baseline of the measurement results observed in the second heating step to the high-temperature side, and a tangent line drawn at the point where the slope of the curve of the step-like portion of the glass transition is maximum. The temperature at this point is defined as the glass transition temperature. In addition, the temperature is raised to 200°C in the first heating step, but this is sufficient as long as the polyester resin is sufficiently melted; if 200°C is insufficient, the temperature should be adjusted accordingly. Similarly, if the cooling temperature of -80°C is insufficient (for example, if the glass transition temperature is lower), the temperature should be adjusted accordingly.

[0076] The number-average molecular weight of the polyester resin is not particularly limited, but as an example, it is between 10,000 and 30,000. The number-average molecular weight used herein is the value measured by gel permeation chromatography (GPC) under the following conditions.

[0077] Measurement device: Tosoh Corporation HLC-8320GPC Column: Tosoh Corporation TSKgel 4000HXL, TSKgel 3000HXL, TSKgel 2000HXL, TSKgel 1000HXL Detector: RI (Differential Refractometer) Data processing: Tosoh Corporation Multi-Station GPC-8020modelII Measurement conditions: Column temperature 40°C Solvent Tetrahydrofuran Flow rate 0.35 ml / min Standard: Monodisperse polystyrene Sample: 100 μl of tetrahydrofuran solution filtered through a microfilter, equivalent to 0.2% by mass in terms of resin solids content

[0078] (Other resins) In the heat sealant of the second embodiment, the resin may consist only of polyester resin, or it may be mainly polyester resin and further contain other resins. Other resins include, as in the first embodiment, (meth)acrylic resins, polyolefin resins, vinyl chloride resins, styrene resins, styrene / butadiene copolymers, styrene / unsaturated carboxylic acid copolymers, acrylonitrile / styrene copolymers, acrylonitrile / butadiene copolymers, ABS resins, AAS resins, AES resins, vinylidene chloride resins, polyurethane resins, poly-4-methylpentene-1 resins, polybutene-1 resins, vinylidene fluoride resins, vinyl fluoride resins, fluorine resins, polycarbonate resins, polyamide resins, acetal resins, polyphenylene oxide resins, polyester resins (polyethylene terephthalate, polybutylene terephthalate, etc.), polyphenylene sulfide resins, polyimide resins, polysulfone resins, polyethersulfone resins, polyarylate resins, olefin / unsaturated carboxylic acid copolymers, and modified versions thereof. These may be used individually or in combination of two or more.

[0079] In the second embodiment, it is preferable that the solid content concentration of polyester resin in the entire resin component contained in the heat sealant is 50% by mass or more. Furthermore, in order to obtain the effects of the present invention, it is preferable that the solid content concentration of polyester resin be adjusted to 60% by mass or more in the entire resin component, more preferably to 70% by mass or more, even more preferably to 80% by mass or more, and it is also preferable that it be 100% by mass of polyester resin (containing no other resins and composed only of polyester resin).

[0080] In the second embodiment, the composition other than the resin component is the same as in the first embodiment described above. In the aqueous heat sealant of the second embodiment, it is preferable to adjust the solid content concentration of the resin component to 20 to 70% by mass.

[0081] In the first and second embodiments, it is preferable that all raw materials used are halogen-free, meaning they do not contain any compounds containing halogen elements.

[0082] <Heat-sealing film for cables> The heat-sealing film for cables of the present invention is formed by applying the aqueous heat-sealing agent of the present invention onto a film substrate and drying it, and the coating film of the heat-sealing agent can be used as a heat-sealing layer.

[0083] The heat-seal film for cables may have the heat-sealing agent coated on only one side of the base film, or it may have the heat-sealing agent coated on both sides of the base film. When a heat-sealing layer is provided on both sides of the base film, the aqueous heat-sealing agent of the present invention also possesses properties such as water resistance and oil resistance. Therefore, after the heat-sealing film is wrapped around the cable, the coated portion of the outer surface of the heat-sealing film, excluding the sealed (adhered) area, functions as a coating agent that provides water resistance and oil resistance.

[0084] Known methods can be used for coating the aqueous composition of the present invention. For example, roll coaters, gravure coaters, flexo coaters, air doctor coaters, blade coaters, air knife coaters, squeeze coaters, impregnation coaters, transfer roll coaters, kiss coaters, curtain coaters, cast coaters, spray coaters, die coaters, offset printing presses, screen printing presses, etc. A drying step in an oven or the like may also be provided after coating.

[0085] The solid content thickness after coating with an aqueous composition, i.e., the thickness of the thermoplastic resin layer, is adjusted as appropriate depending on the desired sealing strength and substrate, but for example, 1 to 10 g / m² ２ It is preferable that the range is 2 to 5 g / m². ２ It is more preferable that it be within that range.

[0086] (Base material) The base material is not particularly limited, and any known plastic film can be used. Specific examples of plastic films include polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyolefin resins such as polyethylene and polypropylene, polystyrene resin, nylon, ethylene-vinyl alcohol copolymer, and other resins known as films, or films made by combining multiple such resins.

[0087] The above-mentioned film may be subjected to some kind of surface treatment, such as physical treatments like corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen or nitrogen gas, glow discharge treatment, or flame treatment, or chemical treatments such as oxidation treatment using chemicals, or other treatments. Alternatively, an untreated film may be used without any surface treatment.

[0088] The above-mentioned film can be manufactured using conventionally known film-forming methods such as extrusion, casting, T-die, cutting, and inflation methods. It may be an unstretched film, or, from the viewpoint of film strength, dimensional stability, and heat resistance, it may be stretched in one or two axes using a tenter method, tubular method, etc.

[0089] The above film may contain additives as needed. Specifically, plastic compounding agents and additives such as elastomers, lubricants, crosslinking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, and pigments may be added to improve or modify properties such as processability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, slipperiness, release properties, flame retardancy, mold resistance, electrical properties, and strength. The amount of additives added should be adjusted within a range that does not affect other properties or recyclability.

[0090] The film thickness of the above-mentioned film is not particularly limited and can be appropriately selected within the range of 0.1 to 300 μm from the viewpoint of lapping properties, moldability, etc. Preferably, it is in the range of 0.3 to 100 μm. If it is less than 0.1 μm, the strength will be insufficient, and if it exceeds 300 μm, the rigidity will be too high, which may make processing difficult.

[0091] The above film may be provided with a barrier layer as needed to provide barrier properties against water vapor, oxygen, alcohol, inert gases, volatile organic compounds (fragrances), etc. Specifically, examples include a coating layer such as polyvinylidene chloride coating (K-coat), a metal vapor-deposited layer such as aluminum, and an inorganic vapor-deposited layer such as silica or alumina.

[0092] The above film may, if necessary, be provided with a printed layer or a coating layer for purposes such as improving ink receptivity when applying a printed layer.

[0093] <Cable> The cable of the present invention has the heat-sealing film for cables, and more specifically, the heat-sealing film is spirally wrapped around a linear cable and bonded (heat-sealed).

[0094] The cable of the present invention is obtained by wrapping a heat-seal film for cables, which has a heat-seal layer formed on its surface with the heat-sealing agent of the present invention, around a cable and heat-sealing it. The heat-seal layer formed with an aqueous composition can be easily softened by heating, allowing it to bond substrates together or a substrate to another material, and then the bonded portion solidifies upon cooling, providing a strong seal between substrates or between substrates and other materials.

[0095] Since the cable of the present invention is heat-sealed with a heat-seal film wrapped around it, excellent adhesive strength due to wrapping is required. The adhesive strength due to wrapping (wrapping properties) can be achieved by the following method: 1. Apply a heat-sealing agent to the base film at a dry application rate of approximately 5 g / m². ２ 1. Apply the coating in the manner described above. 2. Cut the coated sample into 30 mm wide strips. Also, prepare the film to be adhered to (without heat sealant coating) and cut it into 30 mm wide strips.

[0096] 1. Place the cut-out coated sample and the cut-out adherend on top of the adherend with the coated surface of the coated sample facing inward to create a wrapping sample. 3. From one end of a 6 mm diameter round rod towards the other, wrap the wrapping sample spirally around the rod while rotating it. At this time, attach a 100 g weight to the lower end of the wrapping sample and wrap it while keeping it taut to create a test specimen. 4. With the weight still attached to the wrapping sample, place the round rod (test specimen) horizontally on a wire rack (a test tube rack can be used, etc.) and place it in the oven for 30 seconds. Set the oven so that the measured temperature of the sealed part of the wrapping sample is 66 to 77°C. 5. Remove from the oven and leave at room temperature for 5 minutes. 6. Remove the round rod from the test specimen, leaving only the wrapping sample, and leave it at room temperature. 7. The next day, check the adhesion of the wrapping sample with a tensile test machine.

[0097] The laminates and containers of the present invention have excellent recyclability. The recycling method for the printed materials, laminates, and packaging materials of the present invention is not particularly limited and can be carried out using known methods and equipment. In particular, it is suitable for recycling methods that use alkaline treatment for the separate collection of laminates.

[0098] The present invention will be further described in detail by reference to examples. Hereinafter, "parts" and "%" will be based on mass. (Method for preparing the heat sealant) The heat sealant was prepared by mixing the ingredients in the amounts shown in Table 1. In the table, blank spaces indicate no ingredients added, and numbers indicate parts.

[0099]

[0100] The components other than water in the table represent the solid content percentage.

[0101] In Table 1, commercially available ethylene-vinyl acetate copolymers were used.

[0102] For the (meth)acrylic resin, a commercially available acrylic emulsion (polymer of butyl methacrylate, dodecyl methacrylate, and tridecyl methacrylate) was used.

[0103] A commercially available modified polyolefin aqueous dispersion was used as the polyolefin resin.

[0104] A commercially available water-based urethane resin was used.

[0105] (Manufacturing of coated products) Heat sealant H, prepared for PET film (thickness 12 μm), is applied at a coating rate (solid content) of 5 g / m². ２ The coating was applied using a wire bar, and the coated product was dried at 120°C for 20 seconds.

[0106] (Heat sealability evaluation) A thermal gradient heat seal tester (manufactured by Tester Industries Co., Ltd.) was used to evaluate the seal at a temperature of 80°C and a pressure of 2 kg / cm². ２ Under conditions of 1 second, the coated surface of the fabricated coated object and the uncoated surface of PET were bonded together and heat-sealed. The sample width was 15 mm, and the T-type peel strength was measured three times at a tensile speed of 200 mm / min. The average value of these measurements was taken as the heat seal strength.

[0107] The results are shown in Table 1. Note that a higher heat seal strength value indicates greater heat seal strength.

[0108] (Wrapping performance evaluation) 1. Cut the prepared coated material into 30 mm wide strips. Also, prepare a film (uncoated PET) to be adhered to and cut it into 30 mm wide strips. Place the coated surface of the 30 mm wide coated material on top of the 30 mm wide uncoated PET strip to create a wrapping sample. 2. Wrap the prepared wrapping sample spirally around a 6 mm diameter round rod, from one end to the other, rotating the wrapping sample as it goes. At this time, attach a 100 g weight to the lower end of the wrapping sample and wrap it while keeping the test specimen taut to create the test specimen. 3. With the weight still attached to the wrapping sample, place the round rod (test specimen) horizontally on a wire rack (using a test tube rack, etc.) and place it in an oven for 30 seconds. Set the oven so that the measured temperature of the sealing part of the wrapping sample is 66-77°C. 5. Remove from the oven and leave at room temperature for 5 minutes. 6. Remove the round rod from the test specimen, leaving only the wrapping sample, and leave it at room temperature. 7. The adhesion of the wrapping samples was tested using a Shimadzu Corporation EZ test benchtop testing machine. The sample width was set to 15 mm, and the T-type peel strength was measured three times at a tensile speed of 200 mm / min. The average value of these measurements was defined as the heat seal strength.

[0109] The results are shown in Table 1. Note that a higher wrapping value indicates better wrapping performance.

[0110] Furthermore, "substrate failure" in the table means that, during seal strength measurement, the substrate failed without failure occurring in the heat seal layer. "Substrate failure" is a phenomenon that occurs due to strong seal strength.

[0111] Furthermore, a "-" in the table indicates that the material did not adhere in the wrapping performance evaluation test.

[0112] Based on the above results, it was found that the aqueous heat sealant of the present invention is superior in both heat sealability and wrapping properties.

[0113] In contrast, the comparative example heat sealant was found not to have wrapping properties. Therefore, the aqueous heat sealant of the present invention is suitable as a heat sealant for cables.

[0114] Next, the following considerations were made. (Method for preparing the heat sealant) The heat sealant was prepared by mixing the ingredients in the proportions shown in Table 2. In the table, blank spaces indicate no ingredients were added, and the numbers represent parts.

[0115]

[0116] In Table 2, commercially available ethylene-vinyl acetate copolymers were used.

[0117] The polyolefin resin used was a commercially available polypropylene resin that had been acid-modified.

[0118] Cross-linked polymethyl methacrylate was produced using Techpolymer MBX-5 (average particle size 5 μm).

[0119] Silica used was thylysia 550 (average particle size 5 μm).

[0120] Spherical silica used was Cyrosphere C-1504 (average particle size 4.5 μm).

[0121] Solid paraffin was used as the wax.

[0122] The components other than water in the table represent the solid content percentage.

[0123] (Manufacturing of coated products) A heat sealant prepared for PET film (thickness 25 μm) is applied at a coating rate (solid content) of 5 g / m². ２ The material was coated using a wire bar and dried at 120°C for 20 seconds to obtain the coated material. The following evaluations were performed using the prepared coated material. The results are shown in Table 2.

[0124] (Blocking property evaluation) The coated surface and uncoated surface (back of the substrate) of the fabricated coated material are placed on top of each other so that they are in contact, and a pressure of 5 kgf / cm² is applied. ２ The samples were subjected to a load and left in a 40°C environment for 24 hours. After removal, the degree of adhesion between the contact surfaces was evaluated on a five-point scale.

[0125] (Evaluation Criteria) 5: No blocking observed at all. 4: Slight blocking observed, but can be peeled off without any release noise. 3: Blocking is present, and a release noise is heard during peeling. 2: The coated surface and the back of the substrate are bonded, and peeling is not possible at the interface. 1: The coated surface is strongly bonded, and substrate damage occurs during peeling.

[0126] (Heat sealability evaluation) The coated and uncoated surfaces of the fabricated coated material were placed on top of each other, and test pieces were created by heat sealing at temperatures in the range of 100°C to 180°C in 20°C increments using a heat seal tester (all at 0.3 MPa for 1 second). For each test piece, the adhesive strength was recorded using a Shimadzu Corporation EZ test compact desktop tester at a peeling speed of 200 mm / min, T-shaped peeling, and a test piece width of 15 mm.

[0127] (Method for preparing the heat sealant) The heat sealant was prepared by mixing the ingredients in the proportions shown in Table 3. In the table, blank spaces indicate that the ingredient was not added, and the numbers represent parts. The components other than water and alcohol in the table represent the solid content percentage.

[0128]

[0129] The materials used in Table 3 are the same as those used in Table 2.

[0130] (Evaluation of defoaming agents) After preparing the heat sealant according to the formulations shown in Table 3, the dispersibility / mismatch of the defoaming agent was evaluated. For heat sealants with good dispersibility / mismatch (○ or higher), a further defoaming evaluation was performed. The defoaming evaluation here refers to the evaluation of defoaming after placing each liquid sample in a glass bottle and stirring it with a paint shaker for 5 minutes. A rating of ◎ was given for extremely low foam generation, ○ for the next lowest amount, and × for when the majority of the bottle's space was filled with foam.

[0131] The evaluation criteria for dispersibility / mismatch and defoaming properties are as follows: (Dispersibility / Mismatch) ◎: Easily disperses after the addition of the defoaming agent. 〇: Can be dispersed by stirring after the addition of the defoaming agent. ×: Cannot be dispersed.

[0132] (Defoaming properties) ◎: Almost no foam is observed, or if foam occurs, it disappears immediately. 〇: Some foam is generated, but it is judged to be at a level that does not cause problems in coating. ×: Foam is generated, and most of it remains even after standing for 30 minutes. -: Evaluation not performed

[0133] (Heat sealability evaluation) The coated and uncoated surfaces of the coated material prepared in the same manner as in Examples 4 to 7 were placed on top of each other, and test pieces were prepared by heat sealing at temperatures in the temperature range of 100°C to 180°C in 20°C increments using a heat seal tester (all at 0.2 MPa for 1 second). For each test piece, the adhesive strength was recorded using a Shimadzu EZ test compact desktop tester with a peeling speed of 200 mm / min, T-shaped peeling, and a test piece width of 15 mm.

[0134] From the evaluation results, it became clear that the aqueous heat sealant for cables of the present invention has excellent defoaming properties, the coated material exhibits high blocking resistance, and it exhibits excellent heat seal strength over a wide temperature range.

[0135] Next, we investigated water-based heat sealants for highly durable cables, assuming cable use in high-temperature environments. Based on the heat sealant formulation used in Example 9, we investigated heat sealant formulations aimed at providing high durability (heat resistance).

[0136] (Method for preparing the heat sealant) The heat sealant was prepared by mixing the ingredients in the amounts shown in Table 4. In the table, blank spaces indicate that the ingredient was not added, and the numbers represent parts. The ingredients other than water and alcohol in the table represent the solid content ratio. The heat sealant in Example 12 is the same as the heat sealant in Example 9.

[0137]

[0138] The materials used in Table 4 are the same as those used in Tables 2 and 3.

[0139] (Evaluation of compatibility with curing agent) After preparing the heat sealant according to the proportions shown in Table 4, the compatibility with the curing agent was evaluated. Those with good compatibility without curing or gelling were given a rating of ○ or higher.

[0140] The criteria for evaluating compatibility are as follows:

[0141] (Compatibility) ◎: Disperses easily after adding the hardening agent. 〇: Can be dispersed by stirring after adding the hardening agent. ×: Hardening or gelation occurs.

[0142] (Overflow evaluation) 1. Apply approximately 5 g / m² of heat sealant to the base OPP film (20 μm thick) in dry coating amount. ２ 1. Coat the material so that it looks like this. 2. Cut the coated sample into 15 mm wide strips. Also, prepare a film to be used as the substrate (without heat sealant coating) and cut it into 15 mm wide strips. Laminate the cut coated sample and the cut substrate together. Next, prepare a 30 mm wide film and place the prepared laminate on top of the 30 mm wide film to create a sample for checking for excess coating. As shown in Figure 1, the strips are overlapped, and a heat sealant overflow confirmation area 3 is provided at the edges of the film 2 surrounding the laminate 1. 3. Wrap the sample for checking for excess coating around a 6 mm diameter round bar while rotating it so that the sample overlaps. At this time, attach a 500 g weight to the lower end of the sample for checking for excess coating and wrap it with the coated sample taut, wrapping it more than 10 times so that pressure is applied to the sample for checking for excess coating. Once the wrapping is complete, securely fix the end of the wrapped sample with heat-resistant tape to create a test specimen. 4. 1. Place the test specimen horizontally in an oven set to the specified conditions (115°C or 85°C / 85%) and leave it in the oven for the following periods: "115°C - 96 hours (h)", "115°C - 1000 hours (h)", or "85°C / 85% - 1000 hours (h)". 5. Remove from the oven and leave at room temperature for 1 to 2 hours. 6. When removing the sample for overflow evaluation from the rod, visually check whether any heat sealant components have overflowed into the overflow confirmation area 3 of the sample. Evaluate overflow as "yes" or "no".

[0143] As shown in Examples 12 to 15, the results of evaluating the excess heat sealant under high heat resistance conditions confirmed that Examples 13 and 14, in which a curing agent was added, exhibited excellent durability (heat resistance).

[0144] Subsequently, the following evaluations were carried out using the heat sealants of Examples 12 to 14.

[0145] (Manufacture of coated article) The heat sealant adjusted to an OPP film (thickness 20 μm) or a PET film (thickness 25 μm) was applied with a wire bar so that the coating amount (solid content) was 5 g / m ２ and dried at 120 °C for 20 seconds to obtain a coated article. The following evaluations were carried out using the produced coated article. The results are shown in Tables 5, 6, and 7.

[0146] (Heat sealability evaluation) The coated surfaces of the produced coated articles or the coated surface and the non-coated surface were overlapped, and heat sealing was performed at each temperature and time of 10 °C intervals (0.3 MPa for 6 seconds) in the temperature range of 120 °C to 140 °C using a heat seal tester to prepare test pieces. For the PET / copper foil laminate, heat sealing was performed at each temperature and time of 20 °C intervals (0.3 MPa for 3 seconds, 6 seconds, 10 seconds) in the temperature range of 140 °C to 180 °C to prepare test pieces. For each test piece, after one day or more had passed since heat sealing, the adhesive strength at a test piece width of 15 mm was recorded using a small tabletop tester EZ test manufactured by Shimadzu Corporation under the peel rate of 200 mm / min - T-type peel, and under the peel rate of 50 mm / min - 180° peel conditions for PET / copper foil evaluation. In Tables 5 and 6, "laminate storage conditions" indicate the storage conditions when stored for one day after heat sealing. For example, "85 °C / 85% - 1000 h" means stored at 85 °C and 85% humidity for 1000 hours. The PET / copper foil evaluation in Table 7 was stored at room temperature.

[0147] Note that the method of overlapping the laminates is as described in the "heat seal configuration" of each table. In the table, "AL" uses an aluminum foil with a thickness of 9 μm, and the copper foil uses a copper foil with a thickness of 35 μm.

[0148] (Overflow Evaluation) The overflow evaluation of PET / copper foil performed in Table 7 is shown below. 1. A heat sealant is applied to a PET film (thickness 25 μm) which will be the base material, to a dry film thickness of approximately 5 μm. 2. The coated sample is cut to a width of 45 mm. A copper foil to be used as the adherend is also prepared and cut to a width of 50 mm. The coated surface of the cut coated sample and the cut adherend are stacked to form a laminate. 3. The prepared laminate is heat-sealed using a heat seal tester at temperatures ranging from 140°C to 180°C in 20°C increments (0.3 MPa - 3 seconds, 6 seconds, 10 seconds) to create samples for overflow evaluation. 4. The samples for overflow evaluation are removed from the heat sealer and visually inspected to ensure that the heat sealant components do not overflow beyond the contact area between the heat seal bar and the sample for overflow evaluation. The evaluation of overflow is as follows: "Yes" if there is clear overflow, "Slight overflow" if there is slight overflow, and "None" if no overflow is observed at all.

[0149]

[0150]

[0151]

[0152] The evaluation results confirmed excellent heat seal strength in various heat seal configurations. Furthermore, the evaluation results revealed that applying a curing agent to the aqueous heat sealant for cables of the present invention provides excellent overflow suppression. Examples 13 and 14, in which the curing agent was added, met the requirement of a heat seal strength of 1 (N / 15mm) or higher, which is necessary for cable applications, and are considered to have achieved the strength required for cable applications. Moreover, it was revealed that the product exhibits performance that can withstand use even under harsh conditions such as high temperature or high humidity.

[0153] 1. Laminate 2. Film 3. Area for checking for overflow

Claims

1. An aqueous heat sealant for cables, comprising a resin containing ethylene vinyl acetate copolymer or polyester resin, and an aqueous medium.

2. The aqueous heat sealant for cables according to claim 1, comprising an ethylene vinyl acetate copolymer and a (meth)acrylic resin, or an ethylene vinyl acetate copolymer and a polyolefin resin.

3. An aqueous heat sealant for cables according to claim 1 or 2, comprising an antifoaming agent.

4. An aqueous heat sealant for cables according to claim 1 or 2, comprising an anti-blocking agent.

5. The blocking inhibitor is an organic or inorganic fine particle with an average particle size of 0.1 μm or more and 20 μm or less.

6. The aqueous heat sealant for cables according to claim 1 or 2.

7. An aqueous heat sealant for cables according to claim 1 or 2, comprising a crosslinking agent.

8. The aqueous heat sealant for cables according to claim 1 or 2, wherein the aqueous heat sealant does not contain a compound containing a halogen element.

9. A heat-sealable cable film characterized by having the heat-sealing agent described in claim 1 or 2 provided on a substrate.

10. A cable characterized by using the heat-sealable film described in claim 9.

11. The cable according to claim 10, wherein the heat-sealable film is spirally wrapped around the surface of the cable and is bonded to it while wrapped around it via the heat-seal layer of the heat-sealable film.

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