JP7748814B2 - Anti-fog coating composition and its uses - Google Patents

Description

The present invention relates to a coating composition, and more specifically to a coating composition capable of forming a coating layer that exhibits an excellent balance of anti-fogging properties, easy-open properties, and low blocking properties, and uses thereof.

Polymer films are widely used for food packaging containers due to their excellent formability, safety, quality retention, etc. In food packaging containers, water vapor from the contents, etc., may adhere to the surface of the container as water droplets. In this case, the contents (food) of the food packaging container may become invisible, or the food may deteriorate due to the falling of the adhered water droplets. Therefore, anti-fogging agents are used to impart anti-fogging properties to polymer films for food packaging.
For example, a coating composition containing a specific hydrophilic (meth)acrylic resin, an antifogging agent, and a hydrophilic polymer has been proposed as an antifogging agent having excellent antifogging and oil resistance (see, for example, Patent Document 1).

When a coating agent is applied to the surface of a polymer film, the surface condition changes, which can result in changes to blocking properties and heat sealability. Heat-sealable polymer films used as lids for food packaging containers, etc., require low blocking properties during storage and appropriate heat seal strength when opened. Therefore, there is a strong demand for coating agents that can form a coating layer that provides an excellent balance of anti-fogging properties, heat seal strength (easy opening), and low blocking properties without adversely affecting the blocking properties and heat sealability of the heat-sealable layer of the polymer film.

Japanese Patent Application Laid-Open No. 2019-94422

In light of the above technical background, an objective of the present invention is to provide a coating composition that can form an anti-fog coating on the surface of a film containing a heat-fusible polymer, and that can form a film that exhibits a high level of balance between anti-fog properties, heat seal strength (easy opening), and low blocking properties.

As a result of extensive research, the present inventors have found that by applying a composition having a specific reflected infrared spectrum peak to a heat-sealable polymer film, the anti-fogging properties can be significantly improved without substantially impairing the heat seal strength (easy opening property) and low blocking property of the polymer film, and have thus completed the present invention.
That is, the present invention provides:
[1]
The coating composition has a ratio (P4/P2) of the absorption peak height (P2) at 1730 cm ⁻¹ ±30 cm ⁻¹ to the absorption peak height (P4) at 1560 ±30 cm ⁻¹ of 0.08 or more and 1.80 or less in reflection IR spectrum measurement.

The following [2] to [11] are all preferred aspects or embodiments of the present invention.
[2]
The coating composition according to [1], wherein, in reflection IR spectrum measurement, the ratio (P3/P2) of the absorption peak height (P2) at 1730 cm ⁻¹ ±30 ^{cm −1} to the absorption peak height (P3) at 1630 cm −1 ±30 cm −1 is 0.03 or more and 0.60 or less.
[3]
The coating composition according to [1] or [2], wherein, in reflection IR spectrum measurement, the ratio (P1/P2) of the absorption peak height (P2) at 1730 cm ⁻¹ ±30 ^{cm −1 to} the absorption peak height (P1) at 3400 ±30 cm −1 is 0.10 or more and 0.58 or less.
[4]
The coating composition according to any one of [1] to [3], which has a melting point peak at 35±25°C in DSC measurement.
[5]
The coating composition according to [4], further having melting point peaks at 15.3±5°C and 118±15°C in DSC measurement.
[6]
The coating composition according to any one of [1] to [5], comprising (a) a low molecular weight surfactant and (b) a polymer surfactant.
[7]
The coating composition according to [6], wherein the (a) low molecular weight surfactant includes a nonionic surfactant.
[8]
The coating composition according to [6] or [7], wherein the polymer surfactant (b) includes an acrylic surfactant.
[9]
An easily openable film comprising a heat-sealable layer (A), an intermediate layer (B), and a laminate layer (C) laminated in this order, and having a coating layer formed from the coating composition according to any one of [1] to [8] on the heat-sealable layer (A).
[10]
The easy-open film according to [9], wherein the heat-sealing layer (A) contains at least one of polyethylene terephthalate, an ethylene-based (co)polymer, and a propylene-based (co)polymer.
[11]
[9] or [10]. An easy-open package comprising a lid material having the easy-open film according to [9] or [10] and a container.

The coating composition of the present invention can be used to form a coating layer on a substrate such as a heat-sealable film, combining highly practical properties such as anti-fogging, heat seal strength (easy opening), and low blocking at a level that exceeds the limits of conventional technology. The coating composition can be used in a variety of applications, including as a lid for easy-open plastic containers that store various products, such as food, that require visibility of the contents.

1A is a schematic diagram of the evaluation criteria for anti-fogging properties, and FIG. 1B is a photograph of an actual example of anti-fogging evaluation.

The present invention provides a method for measuring reflection IR spectra,
In reflection IR spectrum measurement, the ratio (P4/P2) of the absorption peak height (P2) at 1730 cm ⁻¹ ±30 cm ⁻¹ to the absorption peak height (P4) at 1560 ±30 cm ⁻¹ is 0.08 or more and 1.80 or less.
By having absorption peaks in the above wavelength ranges at the above intensity ratios, the coating composition of the present invention can significantly improve anti-fogging properties without substantially impairing the heat seal strength (easy opening property) and low blocking property of the heat-sealable layer of the polymer film substrate.
The reflection IR spectrum of the coating composition of the present invention can be measured by a method commonly used in the art, for example, by applying the coating composition to a film made of a synthetic resin such as polyethylene terephthalate, drying it by heating to form a coating layer having a thickness of about 2 μm, and measuring the IR spectrum by total reflection absorption infrared spectroscopy. More specifically, the measurement can be performed by the method described in the examples of the present application.

The mechanism by which the coating composition of the present invention can achieve the above-mentioned effects by having the ratio (P4/P2) of the absorption peak height (P2) at 1730 cm ⁻¹ ±30 cm ^{−1 to} the absorption peak height (P4) at 1560 ±30 cm −1 be 0.08 or more and 1.80 or less in reflection IR spectrum measurement is not necessarily clear, but it is presumed that there is some relationship between the absorption peaks at 1730 ^{cm −1} and 1560 cm ⁻¹ within ±30 cm ⁻¹ , respectively, corresponding to ester groups and carbanions, and the presence of these groups and ions at levels observable by reflection IR spectrum measurement, which can impart anti-fogging properties to the substrate through surfactant action.

The intensity P4 of the absorption peak within ±30 cm ⁻¹ of 1560 cm ⁻¹ is preferably 0.1 to 1.7 times, and more preferably 0.15 to 1.5 times, the intensity of the absorption peak within ±30 cm ⁻¹ of 1730 cm ⁻¹ as a reference. That is, (P4/P2) is preferably 0.1 or more and 1.7 or less, and more preferably 0.15 or more and 1.5 or less.
The peak intensity P4 on the reflection IR spectrum measured above was obtained by infrared total reflection measurement (ATR method). From the obtained infrared absorption spectrum, the absorption peak height was calculated by the following procedure (4), and used as the peak intensity.
(4) Connect the absorbance baselines at 1530 cm ⁻¹ and 1780 cm ⁻¹ with a straight line (P), draw a straight line (R) perpendicular to the absorbance peak at 1560 cm ⁻¹ , and determine the length of the straight line (R) from the intersection of the straight line (R) and the straight line (P) to the peak as the peak intensity at 1560 cm ⁻¹ .
The intensity of the absorption peak within 1560 cm ⁻¹ ±30 cm ⁻¹ can be increased by adding a compound having a carbanion and increasing the amount of the compound added, for example, by using a quaternary ammonium salt or a carboxylate and increasing the amount of the compound added.

The peak intensity P2 on the reflection IR spectrum measured above is obtained by infrared total reflection measurement (ATR method). From the obtained infrared absorption spectrum, the absorption peak height is calculated by the following procedure (2), and this is used as the peak intensity.
(2) Connect the absorbance baselines at 1530 cm ⁻¹ and 1780 cm ⁻¹ with a straight line (P), draw a straight line (R) perpendicular to the absorbance peak at 1730 cm ⁻¹ , and determine the length of the straight line (R) from the intersection of the straight line (R) and the straight line (P) to the peak as the absorption peak intensity at 1730 cm ⁻¹ .
The intensity of the absorption peak within 1730 cm ⁻¹ ±30 cm ⁻¹ can be increased by adding a compound having an ester group and increasing the amount of the compound added, for example, by using a (co)polymer of a (meth)acrylic monomer and increasing the amount of the compound added.

The intensity P1 of the absorption peak within ±30 cm ⁻¹ of 3400 ^{cm −1} is not particularly limited, but is preferably 0.15 to 0.55 times, more preferably 0.20 to 0.50 times, and even more preferably 0.25 to 0.48 times the intensity of the absorption peak P2 within ±30 cm ⁻¹ of 1730 cm −1 as a reference. That is, (P1/P2) is preferably 0.1 or more and 0.55 or less, and more preferably 0.2 or more and 0.5 or less.
The peak intensity P1 on the reflection IR spectrum measured above is obtained by infrared total reflection measurement (ATR method). From the obtained infrared absorption spectrum, the absorption peak height is calculated by the following procedure (1), and this is used as the peak intensity.
(1) Connect the absorbance baselines at 3040 cm ⁻¹ and 3800 cm ⁻¹ with a straight line (N), draw a straight line (O) perpendicular to the absorbance peak at 3400 cm ⁻¹ , and determine the length on the straight line (O) from the intersection of the lines (N) and (O) to the peak as the peak intensity at 3400 cm ⁻¹ .
The intensity of the absorption peak within 3400 cm ⁻¹ ±30 cm ⁻¹ can be increased by adding a compound having an OH group, an NH group, and/or a COOH group and by increasing the amount of the compound added. For example, the intensity can be increased by using a glycerin fatty acid ester as the (a) low-molecular-weight surfactant described below and by increasing the amount of the glycerin fatty acid ester used.

The intensity P3 of the absorption peak within 1630 cm ⁻¹ ±30 ^{cm −1} is not particularly limited, but is preferably 0.03 to 0.60 times, more preferably 0.05 to 0.6 times, and particularly preferably 0.1 to 0.55 times the intensity P2 of the absorption peak within 1730 cm −1 ±30 cm ⁻¹ as a reference. That is, (P3/P2) is preferably 0.03 or more and 0.60 or less, preferably 0.1 or more and 0.55 or less, and more preferably 0.2 or more and 0.5 or less.
The peak intensity P3 on the reflection IR spectrum measured above is obtained by infrared total reflection measurement (ATR method). From the obtained infrared absorption spectrum, the absorption peak height is calculated by the following procedure (3), and this is used as the peak intensity.
(3) Connect the absorbance baselines at 1530 cm ⁻¹ and 1780 cm ⁻¹ with a straight line (P), draw a straight line (R) perpendicular to the absorbance peak at 1630 cm ⁻¹ , and determine the length on the straight line (R) from the intersection of the straight lines (R) and (P) to the peak, and the height of the absorption peak at 1630 cm ⁻¹ is the peak intensity.
The intensity of the absorption peak within 1630 cm ⁻¹ ±30 cm ⁻¹ can be increased by adding a compound having an amide group and increasing the amount of the compound added, or by using a quaternary ammonium salt and increasing the amount of the compound added.

The coating composition of the present invention preferably has a melting point peak at 35±25° C. in DSC measurement.
Here, the melting point peak in DSC measurement refers to an endothermic peak observed during the second heating process in DSC measurement under the following thermal history conditions: the coating composition is vacuum dried at 100°C for 7 hours, the first heating is from 30 to 150°C at a heating rate of 10°C/min, and held for 1 minute after heating; then a cooling step (150 to -100°C, heating rate of 10°C/min, and held for 1 minute after heating); and the second heating is from -100 to 150°C at a heating rate of 10°C/min, and held for 1 minute after heating.
By having a melting point peak at 35±25°C, i.e., by containing a component having a melting point peak at 35±25°C, the coating composition of the present embodiment can impart anti-fogging properties to a polymer film or the like having heat-fusible properties without impairing the properties, particularly heat-sealing performance, of the film.
As the component having a melting point peak of 35±25° C., (a) a low molecular weight surfactant, which will be described later, can be preferably used, and more preferably, a glycerin fatty acid ester can be used.

The coating composition of the present invention preferably has a melting point peak at 15.3±5° C. in DSC measurement.
By having a melting point peak at 15.3±5°C, i.e., by containing a component having a melting point peak at 15.3±5°C, the coating composition of the present embodiment can impart anti-fogging properties without impairing the properties of a polymer film having heat-fusible properties, in particular, heat-sealing performance, easy-opening property, sealability, transparency, etc.
As the component having a melting point peak of 15.3±5° C., (a) a low molecular weight surfactant, which will be described later, can be preferably used, and more preferably diglycerin monolaurate can be used.

The coating composition of the present invention preferably has a melting point peak at 118°C ± 15°C in DSC measurement.
By having a melting point peak at 118°C ± 15°C, i.e., by containing a component having a melting point peak at 118°C ± 15°C, the coating composition of the present embodiment can impart anti-fogging properties without impairing the properties of a heat-fusible polymer film, in particular, low blocking, slip properties, transparency, etc.
As the component having a melting point peak of 118°C ± 15°C, the polymer surfactant (b) described below can be preferably used, and more preferably an acrylic surfactant can be used.

The coating composition of the present invention is not particularly limited as long as the reflected IR spectrum has an absorption peak with the above-mentioned intensity ratio. Its components are not particularly limited, but it preferably contains (a) a low-molecular-weight surfactant and (b) a polymeric surfactant. By including (a) a low-molecular-weight surfactant, it is possible to impart anti-fogging properties to heat-sealable polymeric films and the like without impairing their properties, particularly heat-sealing performance, ease of opening, sealability, transparency, etc. By including (b) a polymeric surfactant, it is possible to impart anti-fogging properties to heat-sealable polymeric films and the like without impairing their properties, particularly low blocking, slip properties, transparency, etc.

(a) Low-Molecular-Weight Surfactant There are no particular limitations on the (a) low-molecular-weight surfactant used in the coating composition of the present embodiment, and any low-molecular-weight compound that exhibits surface-active properties can be used as the (a) low-molecular-weight surfactant.
Here, "low molecular weight" means a molecular weight of 5,000 or less. (a) The molecular weight of the low molecular weight surfactant is preferably 3,000 or less, and particularly preferably 1,500 or less.
(a) The low molecular weight surfactant may be any of an anionic low molecular weight surfactant, a cationic low molecular weight surfactant, and a nonionic low molecular weight surfactant.
From the viewpoint of the stability and anti-fogging properties of the coating composition, nonionic low-molecular surfactants are preferred, and fatty acid ester low-molecular surfactants are particularly preferred.

Preferred examples of anionic low-molecular-weight surfactants include alkyl sulfates such as sodium lauryl sulfate, triethanolamine lauryl sulfate, and potassium lauryl sulfate; alkylaryl sulfonic acids such as lignin sulfonates, alkylbenzene sulfonates, and alkylnaphthalene sulfonates, and their salts; sulfosuccinates such as polyoxyethylene alkyl ether sulfates, polyoxyethylene alkylaryl ether sulfates, disodium lauryl sulfosuccinate, disodium lauryl polyoxyethylene alkyl sulfosuccinate, and dioctyl sodium sulfosuccinate; lauryl phosphoric acid; polyoxyethylene alkyl ether phosphates; polyoxyethylene alkyl aryl ether phosphates; and polyoxyethylene styrenated phenol ether sulfate.

Preferred examples of cationic low-molecular-weight surfactants include alkyltrimethylammonium halide salts such as lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, lauryltrimethylammonium bromide, and stearyltrimethylammonium bromide; alkyldimethylbenzylammonium halide salts such as lauryldimethylbenzylammonium chloride, stearyldimethylbenzylammonium chloride, stearyldimethylbenzylammonium chloride, and tri(polyoxyethylene)stearylammonium chloride; stearylpentaethoxyammonium chloride; and chloro-[2-hydroxy-3-(trimethylammonio)propyl]hydroxyethylcellulose.

Preferred examples of the nonionic low-molecular surfactant include alkylolamides such as lauric acid diethanolamide, lauric myristic acid diethanolamide, myristic acid diethanolamide, and polyoxyethylene stearic acid amide; polyoxyethylene alkylphenyl ethers such as polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, and polyoxyethylene dinonylphenyl ether; polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene cetyl ether, and polyoxyethylene stearyl ether; polyethylene glycol fatty acid esters such as polyethylene glycol monooleate, polyethylene glycol dioleate, polyethylene glycol monostearate, and polyethylene glycol distearate; decaglycerin monocaprylate, glycerin monostearate, sorbitan monocaprylate, sorbitan monolaurate, and sorbitan monopalmitate; Examples of the sorbitan fatty acid esters include sorbitan monostearate, sorbitan distearate, sorbitan trioleate, sorbitan sesquioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan trioleate; sorbit fatty acid esters such as polyoxyethylene sorbit monooleate and polyoxyethylene sorbit tetraoleate; polyoxyethylene polyoxypropylene alkyl ethers (blocked), polyoxyethylene polyoxypropylene glycol, and polyoxyethylene polyoxypropylene alkyl ethers such as ethylenediaminetetrapolyoxyethylene polyoxypropylene; polyoxyethylene alkylaryl ethers; polyoxyethylene styrenated phenol ethers; polyoxyethylene alkyl esters; and polyoxyethylene styrenated phenol ether polymers.
Among these, fatty acid esters are preferred, polyhydric alcohol fatty acid esters are more preferred, and glycerin fatty acid esters are particularly preferred. More specifically, glycerin monostearate, glycerin monolaurate, diglycerin monostearate, diglycerin monolaurate, decaglycerin oleate, decaglycerin laurate, etc. are particularly preferably used.

(b) Polymer Surfactant There are no particular limitations on the polymer surfactant (b) used in this embodiment, and any polymer compound that exhibits surface activity can be used as the polymer surfactant (b).
Here, "polymer" means a molecular weight of at least 5,000. The molecular weight of (b) the polymer surfactant is preferably 10,000 to 1,000,000, and particularly preferably 10,000 to 500,000.

The (b) polymer surfactant is preferably water-soluble. There are no particular limitations on the structure of the (b) polymer surfactant, but it is desirable that the polymer surfactant has a structure that has a water-insoluble polymer main chain and water-soluble groups in its side chains, thereby making the polymer compound as a whole water-soluble.
The polymer surfactant (b) may be any of anionic polymer surfactants, cationic polymer surfactants, and nonionic polymer surfactants. The type of polymer surfactant typically depends on the type, number, proportion, etc. of the side chain groups.
The (b) polymer surfactant may be any of a natural polymer surfactant, a semi-synthetic polymer surfactant, and a synthetic polymer surfactant, but from the viewpoints of control of the structure and physical properties and ease of availability, a synthetic polymer surfactant is preferable.

Preferred examples of the anionic polymer surfactant include (co)polymers of (meth)acrylic acid, maleic acid, etc., carboxymethyl cellulose, carboxy starch, (meth)acrylic acid grafted starch, sodium alginate, sodium pectinate, xanthan gum, etc.
Among these, acrylic polymer surfactants, that is, (co)polymers of (meth)acrylic monomers are preferably used.

Examples of (meth)acrylic monomers used in (co)polymers of (meth)acrylic monomers include (meth)acrylic monomers having a hydroxy group, (meth)acrylic monomers having a carboxy group, (meth)acrylic acid ester monomers, (meth)acrylic monomers having a silyl group, and (meth)acrylic monomers having an isocyanate group.

The (meth)acrylic monomer having a hydroxy group is not particularly limited, but examples include 2-hydroxyethyl (meth)acrylate (HEMA), 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, and 2,3-dihydroxypropyl (meth)acrylate. Of these, it is preferable to use 2-hydroxyethyl methacrylate (HEMA), 2-hydroxyethyl acrylate, and 2-hydroxypropyl acrylate.

(Meth)acrylic monomers having a carboxy group are not particularly limited, but include unsaturated monocarboxylic acids such as (meth)acrylic acid, ((meth)acryloyloxy)acetic acid, 2-carboxyethyl (meth)acrylate, 3-carboxypropyl (meth)acrylate, 1-[2-((meth)acryloyloxy)ethyl] succinate, 1-(2-(meth)acryloyloxyethyl) phthalate, 2-((meth)acryloyloxy)ethyl hydrogen hexahydrophthalate, and lactone-modified versions of these; unsaturated dicarboxylic acids (such as maleic acid), acid anhydrides (such as succinic anhydride and maleic anhydride) and carboxyl group-containing polyfunctional (meth)acrylates obtained by reacting them with hydroxyl group-containing polyfunctional (meth)acrylates (pentaerythritol triacrylate). Of these, from the viewpoint of ease of adjusting the acid value, it is preferable to use methacrylic acid, (acryloyloxy)acetic acid, 2-carboxyethyl acrylate, and 3-carboxypropyl acrylate, and it is more preferable to use methacrylic acid.

The (meth)acrylic acid ester monomer is not particularly limited, but examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, ... Allyl (meth)acrylate, isobornyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-pentafluoropropyl (meth)acrylate, perfluorocyclohexyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, β-(perfluorooctyl)ethyl (meth)acrylate, glycidyl (meth)acrylate ) acrylate, allyl glycidyl ether, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, glycerol mono(meth)acrylate, aminoethyl (meth)acrylate, N-monoalkylaminoalkyl (meth)acrylate, N,N-dialkylaminoalkyl (meth)acrylate, 2-aziridinylethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, allyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and allyl (meth)acrylate can be exemplified.

Examples of (meth)acrylic monomers having a silyl group include, but are not limited to, gamma-(meth)acryloxypropyltrimethoxysilane, gamma-(meth)acryloxypropyltriethoxysilane, gamma-(meth)acryloxypropylmethyldimethoxysilane, gamma-(meth)acryloxypropylmethyldiethoxysilane, and gamma-(meth)acryloxypropyltriisopropoxysilane.

The (meth)acrylic monomer having an isocyanate group is not particularly limited, but examples include (meth)acryloyl isocyanate, and (meth)acryloyl isocyanate ethyl phenol or methyl ethyl ketoxime adducts.

Furthermore, the other monomer is not particularly limited, but examples thereof include vinyl esters, vinyl ethers, nitrile group-containing ethylenically unsaturated monomers, vinyl compounds having an aromatic ring, polymerizable monomers containing a methylolamide group or an alkoxylated thereof, silyl group-containing polymerizable monomers, oxazoline group-containing polymerizable monomers, amide group-containing polymerizable monomers, carbonyl group-containing polymerizable monomers, and other compounds.
When other monomers are used, the proportion of the structural units derived from the other monomers in the acrylic polymer surfactant is preferably 10 to 90 mol %, and particularly preferably 30 to 70 mol %.

Commercially available acrylic polymer surfactants that can be used in the present invention include, for example, Dexnol RS-811 (manufactured by Nippon Nyukazai Co., Ltd.), BYK-3441 (manufactured by BYK Japan KK), BYK-350 (manufactured by BYK Japan KK), BYK-381 (manufactured by BYK Japan KK), and Elecut C048 (manufactured by Takemoto Oil & Fat Co., Ltd.).

Other preferred examples of anionic polymer surfactants include polyvinylpyridine, polyvinylpyrrolidone, polyethyleneimine, cationic starch, chitosan, etc.

Preferred examples of nonionic polymer surfactants include polyoxyethylene-polyoxypropylene, polyvinyl alcohol, polyvinyl ether, polyacrylamide, ethylene oxide adducts of alkylphenol formaldehyde condensates, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, corn starch, and various starches.

Further, more specific examples of suitable polymer surfactants include the following:
(1) Poly(4-vinylpyridine) type cationic surfactants; (2) Graft copolymers of cationic derivatives of linear polysaccharides and olefin monomers; (3) Copolymers of cationic monomers and nonionic monomers (e.g., copolymers of alkylvinylpyridinium and alkylene oxide adducts of alkylvinyl alcohol).
(4) Poly 2-hydroxy-3-methacryloyloxypropyltrimethylammonium chloride (5) Polydimethylaminoethyl methacrylate (6) Salts of acrylic acid polymers with alkali metals, amines, and ammonia (7) Copolymers of maleic anhydride and acrylic acid and their salts with alkali metals, amines, and ammonia (8) Copolymers of itaconic acid and acrylic acid and their salts with alkali metals, amines, and ammonia (9) Alkali metal salts of sulfonated styrene-maleic anhydride copolymer (10) Alkali metal salts of polyvinyl sulfonic acid (11) Alkali metal salts of polystyrene sulfonic acid (12) Polymethacryloyloxypropyls Sulfonic acid (13) Alkali metal salt of polyepoxysuccinic acid (14) Formalin condensation product of sodium naphthalenesulfonate (15) Melamine-formalin condensation product of sulfonic acid (16) Copolymer of alkylaminoalkyl(meth)acrylamide and alkylacrylamide (meth)acrylate or acrylonitrile (17) Fatty acid dextrin (18) Carboxymethyl cellulose (19) Polyvinyl alcohol (20) Polyoxyethylene (hereinafter abbreviated as POE)-polyoxypropylene (hereinafter abbreviated as POP) block polymer (21) Ethylenediamine-POE·POP block polymer (22) POE-POP triblock polymer

The solvent coating composition may optionally contain a solvent such as water or an organic solvent.
The solvent is not particularly limited, but water, a water-soluble solvent, a non-water-soluble solvent, etc. can be preferably used. Here, the term "water-soluble solvent" refers to a solvent that, when gently stirred with an equal volume of pure water at 1 atmosphere and 20°C, produces a mixed solution that has a uniform appearance after the flow has subsided. On the other hand, the term "non-aqueous solvent" refers to a solvent that, when gently stirred with an equal volume of pure water at 1 atmosphere and 20°C, produces a mixed solution that cannot maintain a uniform appearance after the flow has subsided.

The water-soluble solvent is not particularly limited, but preferred examples include alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol methyl ether, and diethylene glycol methyl ether; ketones such as acetone; and ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, and diethylene glycol dimethyl ether.

Preferred examples of the non-water-soluble solvent include ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; hydrocarbons such as hexane, heptane, and octane; aromatics such as benzene, toluene, xylene, and cumene; and esters such as ethyl acetate and butyl acetate.

These solvents may be used alone or in combination of two or more.
There is no particular limitation on the amount of solvent used, but in the above embodiment, when the entire coating composition is taken as 100 parts by mass, the solvent is preferably used in an amount such that the total amount of (a) the low-molecular-weight surfactant and (b) the polymer surfactant is 0.1 to 15 parts by mass, and particularly preferably 0.1 to 5.0 parts by mass.

Other Components The coating composition may contain additives other than (a) the low molecular weight surfactant, (b) the polymer surfactant, and the solvent, as needed.
The additives are not particularly limited, but examples thereof include anti-fogging aids, slip agents (such as silicone emulsions containing polydimethylsiloxane as a main component), antistatic agents, antioxidants, antibacterial agents, ultraviolet absorbers, etc. These additives may be used alone or in combination of two or more.

Uses of the Coating Composition Although there are no particular limitations on the form in which the coating composition is used, it is preferable to apply the composition to a film substrate such as a heat-sealable film to form a coating layer.
The coating method is not particularly limited, but preferred examples include a spray coater, a roll coater, a gravure roll coater, a knife coater, an air knife coater, a rotor dampening, and an applicator system.

In forming the coating layer, heating and drying may be carried out after coating.
There are no particular limitations on the drying temperature, but when the composition is applied to a heat-fusible polymer film, it is preferable to dry the composition at a temperature not exceeding the glass transition temperature (Tg) of the film.
The drying time is not particularly limited, but is preferably 0.01 to 10 minutes, and more preferably 0.05 to 3 minutes.

There is no particular limitation on the thickness of the coating layer, but it is preferably 0.2 to 0.005 μm, and particularly preferably 0.1 to 0.005 μm.
When specifying the coating layer by its coating amount (mass), the coating amount of the coating layer after drying is preferably 0.2 g/ ^m2 or less, from the viewpoint of not impairing the function of the substrate film or the like.
On the other hand, from the viewpoint of fully realizing the effect of the coating, it is preferable that the coating amount of the coating layer is 0.005 g/m ² or more after drying.
The coating amount of the coating layer after drying is more preferably 0.2 to 0.005 g/m ² , and particularly preferably 0.1 to 0.005 g/m ² .
The amount of coating layer applied can be calculated from the difference in mass between the heat-sealable film before and after the coating layer is formed, and the area of the heat-sealable film.

[0043] There is no particular limitation on the substrate to which the coating composition of the present invention is applied, but it is preferably applied to a polymer film having heat-fusible properties. In this case, it is possible to form a coating layer that is excellent in balance between anti-fogging properties, heat-sealing strength (easy opening), and low blocking properties without adversely affecting the blocking properties and heat-sealing properties of the polymer film having heat-fusible properties (heat-fusible layer).
The heat-fusible polymer film in this embodiment preferably contains at least one of polyester, ethylene-based (co)polymer, and propylene-based (co)polymer, and particularly preferably contains at least one of polyethylene terephthalate, ethylene-based (co)polymer, and propylene-based (co)polymer.
When the coating composition of the present invention is applied to a heat-fusible polymer film containing any of these, it can form a coating layer that has an excellent balance of anti-fogging properties, heat seal strength (easy opening), and low blocking properties.

The polyester contained in the polymer film of this embodiment is preferably amorphous (non-crystalline) or low-crystalline from the viewpoint of realizing excellent heat-sealing properties. The polyester may contain, as a dibasic acid component, a component selected from phthalic acid, terephthalic acid, isophthalic acid, adipic acid, sebacic acid, naphthalenedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-phenylenedioxydiacetic acid, and structural isomers thereof, dicarboxylic acids or derivatives thereof such as malonic acid, succinic acid, and adipic acid, p-hydroxybenzoic acid, p-hydroxybenzoic acid esters, and oxyacids or derivatives thereof such as glycolic acid, and ethylene glycol as a glycol component. and aliphatic glycols such as diethylene glycol, neopentyl glycol, hexanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and pentamethylene glycol; alicyclic glycols such as cyclohexanedimethanol; and aromatic dihydroxy compound derivatives such as bisphenol A and bisphenol S. One or more of these are selected from these and combined to carry out an ester exchange reaction or esterification reaction between the dibasic acid component and the glycol component, followed by a melt polycondensation reaction, and the resulting product can be used.

Lactic acid polymers can also be used as polyesters, and examples include, but are not limited to, poly(D-lactic acid), poly(L-lactic acid), copolymers of D-lactic acid and L-lactic acid, copolymers of D-lactic acid and other hydroxycarboxylic acids, copolymers of L-lactic acid and other hydroxycarboxylic acids, blends of these, and copolymers of a polyester component obtained by esterifying a dicarboxylic acid and a diol with a lactic acid component. Of these, polylactic acid, whose main structural unit is L-lactic acid, is particularly preferred from the standpoint of film formation stability.

Examples of the hydroxycarboxylic acids, diols, and dicarboxylic acids include hydroxycarboxylic acids such as hydroxycaproic acids such as glycolic acid, hydroxybutyric acid, and hydroxycaproic acid; cyclic lactones such as caprolactone, butyrolactone, lactide, and glycolide; aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; and aliphatic dicarboxylic acids such as succinic acid, adipic acid, suberic acid, and sebacic acid.

The polyester used in this embodiment is preferably polyethylene terephthalate, and amorphous copolymerized polyethylene terephthalate resin, which is a combination of a dibasic acid component and a glycol component and has a glass transition temperature Tg of approximately -20 to 90°C, preferably -15 to 85°C, is particularly suitable.

Ethylene-Based (Co)Polymer The polymer film in this embodiment preferably contains an ethylene-based (co)polymer in the heat-sealable layer, more preferably in an amount of 1 to 99% by mass based on the mass of the heat-sealable layer.
When the content of the ethylene-based (co)polymer is 10% by mass or more, heat fusion bonding property is exhibited, which contributes to realizing the effects of the present embodiment. The content of the ethylene-based (co)polymer is more preferably 18% by mass or more, and particularly preferably 47% by mass or more.
The content of the ethylene-based (co)polymer of 90% by mass or less contributes to the development of easy-open properties and the realization of the effects of the present embodiment. The content of the ethylene-based (co)polymer is preferably 85% by mass or less, and particularly preferably 80% by mass or less.

There are no particular restrictions on the type of ethylene-based (co)polymer, and it may be either an ethylene homopolymer or a copolymer of ethylene and a monomer other than ethylene. In the case of a copolymer of ethylene and a monomer other than ethylene, the proportion of ethylene-derived structural units will be greater than 50 mol%. Having a proportion of ethylene-derived structural units greater than 50 mol% distinguishes the ethylene-based (co)polymer from propylene-based (co)polymers, etc., described below. The proportion of ethylene-derived structural units is preferably 55 mol% or more, and particularly preferably 60 mol% or more.

The ethylene-based (co)polymer may be used alone or in combination of two or more kinds.
From the viewpoint of controlling the heat-sealing properties of the polymer film, it is preferable to use a combination of two or more types, and it is preferable to use an ethylene polymer having a density of 900 kg/ ^m3 or more and 960 kg/ ^m3 or ^less , both of which will be described later, and an ethylene-α-olefin copolymer having a density of less than 900 kg/m3, and it is particularly preferable to use these in combination with a propylene (co)polymer, a tackifying resin, etc., which will be described later.

(i) an ethylene (co)polymer having a density of 900 kg/m ³ or more and 960 kg/m ³ or less;
The polymer film in this embodiment preferably contains an ethylene-based (co)polymer (hereinafter also referred to as ethylene-based (co)polymer (i)) having a density of 900 kg/m or ^more and 960 kg/m or ^less , and more preferably contains 1 to 50 mass% of the ethylene-based (co)polymer.
It is preferable to contain the ethylene (co)polymer (i) in an amount of preferably 1% by mass or more from the viewpoints of heat-sealing properties, easy opening properties, sealability, etc.
The content of the ethylene (co)polymer (i) of 50% by mass or less improves impact resistance, contributing to realizing the effects of the present embodiment. The content of the ethylene (co)polymer (i) is preferably 45% by mass or less, and particularly preferably 35% by mass or less.

The ethylene-based (co)polymer (i) has a proportion of ethylene-derived structural units of 50 mol% or more, and therefore a proportion of propylene-derived structural units of less than 50 mol%, and is therefore distinguishable from propylene-based polymers in this respect. Furthermore, the ethylene-based (co)polymer (i) has a density of 900 kg/ ^m3 or more, and is therefore distinguishable from the ethylene-α-olefin copolymer (ii) described below, which has a density of less than 900 kg/ ^m3 .

The ethylene (co)polymer (i) has a density in the range of 900 to 960 kg/m ³ , preferably 905 to 930 kg/m ³ , and more preferably 908 to 920 kg/m ³ .
The density of the ethylene (co)polymer (i) can be measured by Method D (density gradient tube method) of JIS K 7112 using a sample treated with boiling water for 30 minutes.
The density of the ethylene (co)polymer (i) can be adjusted by a conventionally known method. For example, the density can be reduced by increasing the amount of copolymerization components other than ethylene or by increasing the amount of branches by a high-pressure method or the like.

The ethylene (co)polymer (i) may be a homopolymer of ethylene, or a copolymer of ethylene with other copolymerization components such as an α-olefin having 3 to 10 carbon atoms.
As the other copolymerization component, as described above, it is preferable to use an α-olefin having 3 to 10 carbon atoms, such as propylene, 1-butene, 1-heptene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc., but the present invention is not limited to these, and other copolymerization components such as polyenes such as dienes, polar monomers, etc. When the ethylenic (co)polymer (i) is a copolymer, it may be either a random copolymer or a block copolymer, but is preferably a random copolymer.
The content of the structural units derived from other copolymerization components may be less than 50 mol %, but is usually 30 mol % or less, and particularly preferably 20 mol % or less.

As for classification of polymers, suitable examples of ethylene (co)polymers (i) include ethylene homopolymers or ethylene-α-olefin copolymers called high-pressure low-density polyethylene (HP-LDPE), linear or straight-chain low-density polyethylene (L-LDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE). Details of these suitable polymers are the same as those conventionally known in the technical field, so long as they satisfy the condition of 900 kg/m ^{or more} and 960 kg/m or ^less .

The ethylene (co)polymer (i) having a density of 900 kg/m ³ or more and 960 kg/m ³ or less may be used alone or as a mixture of two or more kinds.

The melt flow rate (MFR) (ASTM D1238, 190°C, 2160 g load) of the ethylene (co)polymer (i) having a density of 900 kg/m ^{or more} and 960 kg/m or ^less is not particularly limited as long as it has film-forming ability when used alone or mixed with other components, but is usually in the range of 0.01 to 100 g/10 min, preferably 0.1 to 70 g/10 min.
The melt flow rate of the ethylene-based (co)polymer (i) can be adjusted by a method conventionally used in the art, and for example, the melt flow rate can be increased by decreasing the molecular weight or increasing the molecular weight distribution.

The molecular weight distribution (M _w /M _n ) of the ethylene (co)polymer (i) measured by gel permeation chromatography (GPC) is usually in the range of 1.5 to 4.0, preferably 1.8 to 3.5. The ethylene (co)polymer (i) also preferably has one or more sharp endothermic peaks as determined from an endothermic curve measured by a differential scanning calorimeter (DSC) at a heating rate of 10°C/min, and the maximum temperature of the peak, i.e., the melting point, is usually in the range of 50 to 130°C, preferably 60 to 120°C.

The above-described ethylene (co)polymer (i) can be prepared by a conventional production method using a multi-site catalyst, typically a Ziegler catalyst, or a single-site catalyst, typically a metallocene catalyst. For example, linear low-density polyethylene (LLDPE), which is preferably used as the ethylene (co)polymer (i), can be prepared using a catalyst containing a transition metal metallocene compound. This meta-octene compound-containing catalyst is preferably formed from (a) a transition metal meta-octene compound, (b) an organoaluminum oxy-compound, and (c) a support. If necessary, it may also be formed from these components and (d) an organoaluminum compound and/or an organoboron compound. Olefin polymerization catalysts containing such metallocene compounds and methods for preparing linear low-density polyethylene (LLDPE) using the catalyst are described, for example, in JP-A-8-269270.

(ii) an ethylene/α-olefin copolymer having a density of less than ⁹⁰⁰ kg/m
The polymer film in this embodiment preferably contains an ethylene-α-olefin copolymer ( ^hereinafter also referred to as ethylene-α-olefin copolymer ( ⁱⁱ )) having a density of less than 900 kg/ ^m3 , together with or instead of the ethylene (co)polymer (i) having a density of 900 kg/m3 or more and 960 kg/m3 or less.

The ethylene-α-olefin copolymer (ii) has a proportion of ethylene-derived structural units of 50 mol% or more, and therefore a proportion of propylene-derived structural units of less than 50 mol%, and is therefore distinguishable from propylene-based (co)polymers in this respect. Furthermore, the ethylene-α-olefin copolymer (ii) has a density of less than 900 kg/ ^m3 , and is therefore distinguishable from ethylene-based (co)polymers (i) having a density of 900 kg/ ^m3 or more.
The ethylene/α-olefin copolymer (ii) having a density of less than 900 kg/m ³ is preferably a random copolymer.

The ethylene/α-olefin copolymer (ii) may be a single copolymer or a combination of two copolymers.
A suitable example of the latter is a resin composition composed of an ethylene-α-olefin random copolymer (ii-1) having a density in the range of 860 to 895 kg/ ^m3 and at least one α-olefin having 4 to 10 carbon atoms, and an ethylene-propylene random copolymer (ii-2) having a density in the range of 865 to 875 kg/ ^m3 .
Furthermore, a resin composition composed of preferably 10 to 90 parts by mass, particularly preferably 30 to 90 parts by mass, of an ethylene-α-olefin random copolymer (ii-1) and 90 to 10 parts by mass, particularly preferably 70 to 10 parts by mass of an ethylene-propylene random copolymer (ii-2) (wherein (ii-1) + (ii-2) = 100 parts by mass) can be used.

The ethylene/α-olefin random copolymer (ii-1) is preferably a polymer having at least one of the following physical properties [ii-1a] to [ii-1c].
[ii-1a] The ethylene content is 85 to 93 mol%. [ii-1b] The crystallinity by X-ray is 7 to 30%. [ii-1c] The melting point determined from the endothermic curve at a heating rate of 10°C/min using a differential scanning calorimeter (DSC) is in the range of 60 to 90°C.

That is, as the ethylene/α-olefin random copolymer (ii-1), an ethylene/α-olefin random copolymer having the physical properties of [ii-1a], [ii-1b], or [ii-1c] is preferred, an ethylene/α-olefin random copolymer having the physical properties of [ii-1a] and [ii-1b], the physical properties of [ii-1a] and [ii-1c], or the physical properties of [ii-1b] and [ii-1c] is more preferred, and an ethylene/α-olefin random copolymer having the physical properties of [ii-1a], [ii-1b], and [ii-1c] is particularly preferred.

Similarly, the ethylene-propylene random copolymer (ii-2) is preferably a polymer having at least one of the following physical properties [ii-2a] and [ii-2b].
[ii-2a] Ethylene content is 75 to 85 mol%. [ii-2b] Amorphous or slightly crystalline with a degree of crystallinity by X-ray of less than 5%. That is, as the ethylene-propylene random copolymer (ii-2), an ethylene-propylene random copolymer having the physical properties of [ii-2a] or [ii-2b] is preferred, and an ethylene-propylene random copolymer having the physical properties of [ii-2a] and [ii-2b] is particularly preferred.

Among these copolymers, taking into consideration the heat-sealing properties of the resulting heat-sealable film, compositions (mixtures) consisting of a low-crystalline ethylene/α-olefin random copolymer (ii-1) having an ethylene content of 85 to 93 mol%, a crystallinity of 7 to 30% as determined by X-ray analysis, and a melting point in the range of 60 to 90°C as determined from an endothermic curve at a heating rate of 10°C/min using a differential scanning calorimeter (DSC), and an amorphous or slightly crystalline ethylene/propylene random copolymer (ii-2) having an ethylene content of 75 to 85 mol% and a crystallinity of less than 5% as determined by X-ray analysis, are particularly suitable for use as the ethylene/α-olefin copolymer (ii).

The ethylene/α-olefin copolymer (ii) having a density of less than 900 kg/ ^m3 that can be used for the polymer film of this embodiment is not particularly limited in melt flow rate (MFR) (ASTM D1238, 190°C, 2160 g load) as long as it has film-forming ability when used alone or when mixed with other components to form an olefin polymer composition. However, in consideration of the processability, oil resistance, and the like of the olefin polymer composition, the melt flow rate (MFR) (ASTM D1238, 190°C, 2160 g load) is preferably in the range of 0.01 to 20 g/10 min, more preferably 0.1 to 10 g/10 min.
The ethylene/α-olefin copolymer (ii) having a density of less than 900 kg/ ^m3 that can be used for the polymer film of this embodiment can be obtained by copolymerizing ethylene with an α-olefin or the like using a catalyst comprising, for example, a transition metal compound catalyst component, such as a vanadium compound or a zirconium compound, and an organoaluminum compound catalyst component.

Propylene-Based (Co)Polymer The polymer film in this embodiment preferably contains a propylene-based (co)polymer in the heat-sealable layer, more preferably in an amount of 10 to 70% by mass based on the total mass of the heat-sealable layer.
When the content of the propylene-based (co)polymer is 10% by mass or more, the heat-sealing property and rigidity are obtained, which contributes to realizing the effects of the present embodiment. The content of the propylene-based (co)polymer is more preferably 30% by mass or more, and particularly preferably 35% by mass or more.
When the content of the propylene-based (co)polymer is 70% by mass or less, the package has easy-open properties, which contributes to realizing the effects of the present embodiment. The content of the propylene-based (co)polymer is preferably 65% by mass or less, and particularly preferably 60% by mass or less.

Propylene-based (co)polymers are resins generally manufactured and sold under the name of polypropylene, and are usually propylene homopolymers or propylene copolymers having a density of about 890 to 930 kg/ ^m3 , i.e., copolymers comprising propylene and at least one comonomer selected from other α-olefins in small amounts.
The copolymer may be a random copolymer or a block copolymer, but a random copolymer is particularly preferred. Examples of other α-olefins in this propylene copolymer include ethylene and α-olefins having about 4 to 20 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene. Such other α-olefins may be copolymerized alone or in combination with two or more α-olefins. In addition, the presence of comonomers other than the α-olefin is not excluded.

Propylene-based (co)polymers are distinguished from ethylene-based (co)polymers and the like by having a proportion of propylene-derived structural units of 50 mol % or more. The proportion of propylene-derived structural units is preferably 60 mol % or more, and particularly preferably 70 mol % or more.
Since the proportion of propylene-derived structural units is 50 mol% or more, the proportion of comonomer-derived structural units is less than 50 mol%. In ordinary polypropylene, the proportion of comonomer-derived structural units is often 25 mol% or less. In the case of a random copolymer, it is preferably 10 mol% or less, and particularly preferably 5 mol% or less. In the case of a block copolymer, it is preferably 20 mol% or less, and particularly preferably 15 mol% or less.

Of these propylene-based (co)polymers, propylene-α-olefin random copolymers having a melting point measured by a differential scanning calorimeter (DSC) in the range of 110 to 145°C, particularly 115 to 140°C, are preferred in terms of the balance between heat-sealability and heat resistance of the resulting heat-sealable film.

As long as the propylene (co)polymer has film-forming ability, either alone or in a mixture with other components that make up the polymer film, such as an ethylene (co)polymer or a tackifying resin, its melt flow rate (MFR) (ASTM D1238, 230°C, 2160 g load) is not particularly limited, but from the perspective of extrusion processability, it is typically in the range of 0.01 to 100 g/10 min, preferably 0.1 to 70 g/10 min.

In polymer films, two or more types of propylene-based (co)polymers can be used in combination as the propylene-based (co)polymer.

Propylene (co)polymers can be produced by various known production methods, specifically, using olefin polymerization catalysts such as Ziegler-Natta catalysts and single-site catalysts. In particular, they can be produced using single-site catalysts. Single-site catalysts are catalysts with uniform (single-site) active sites, such as metallocene catalysts (also known as Kaminsky catalysts) and Brookhart catalysts. Metallocene catalysts are catalysts consisting of a metallocene transition metal compound and at least one compound selected from the group consisting of organoaluminum compounds and compounds that react with the metallocene transition metal compound to form an ion pair, and may be supported on an inorganic material.

Tackifying Resin The tackifying resin that can be used in the polymer film of the present embodiment is a known resin that is manufactured and sold as a tackifier, and specific examples thereof include aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, aromatic hydrocarbon resins, polyterpene resins, rosins, styrene resins, and coumarone-indene resins.

Examples of aliphatic hydrocarbon resins include resins obtained by polymerizing a fraction containing at least one mono- or diolefin having 4 to 5 carbon atoms, such as 1-butene, isobutene, butadiene, 1,3-pentadiene, and isoprene.
Examples of alicyclic hydrocarbon resins include resins obtained by cyclodimerizing and then polymerizing diene components in a spent C4-C5 fraction, resins obtained by polymerizing cyclic monomers such as cyclopentadiene, and resins obtained by intranuclear hydrogenation of aromatic hydrocarbon resins.
Examples of aromatic hydrocarbon resins include resins obtained by polymerizing a fraction containing at least one C8 to C10 vinyl aromatic hydrocarbon such as vinyltoluene, indene, and α-methylstyrene, and resins obtained by copolymerizing these fractions with the above-mentioned aliphatic hydrocarbon fractions.

Examples of polyterpene resins include α-pinene polymers, β-pinene polymers, dipentene polymers, terpene-phenol copolymers, α-pinene-phenol copolymers, and hydrogenated products thereof.
Rosins include gum rosin, wood rosin, tall oil rosin, and modified products thereof, and examples of modified products include those that have been subjected to modifications such as hydrogenation, disproportionation, dimerization, and esterification.
Examples of styrene hydrocarbon resins include low molecular weight resinous polymers obtained by polymerizing one or more styrene monomers such as highly pure styrene, vinyltoluene, α-methylstyrene, and isopropyltoluene.

When using the heat-sealable polymer film of this embodiment as an easy-open material for food and beverage packaging, taking into consideration odorlessness, food hygiene, miscibility with other components, etc., it is preferable to use a nuclear-hydrogenated aromatic hydrocarbon resin or a polyterpene resin as the tackifying resin.

Although there are no particular limitations on the blend of resins constituting the heat-fusible polymer film of this embodiment, it is preferable that the ethylene-α-olefin copolymer (ii) and/or tackifying resin (d) having a density of less ^than 900 kg/m3 be contained in a total amount of 1 to 50 mass%. In this case, as long as the total content of the ethylene-α-olefin copolymer (ii) and/or tackifying resin is 1 to 50 mass%, the film may contain only the ethylene-α-olefin copolymer (ii), only the tackifying resin, or both the ethylene-α-olefin copolymer (ii) and the tackifying resin.

When the total content of the ethylene-α-olefin copolymer (ii) and/or tackifying resin is 1% by mass or more, the pouch has heat-sealing properties and easy-opening properties, which contributes to realizing the effects of the present embodiment. The total content of the ethylene-α-olefin copolymer (ii) and/or tackifying resin is more preferably 5% by mass or more, and particularly preferably 10% by mass or more.
By having the total content of the ethylene-α-olefin copolymer (ii) and/or tackifying resin be 99% by mass or less, the film has heat-sealing properties, easy-opening properties, and impact resistance, which contributes to realizing the effects of the present embodiment. The total content of the ethylene-α-olefin copolymer (ii) and/or tackifying resin is more preferably 95% by mass or less, and particularly preferably 90% by mass or less.

The heat-sealable film of this embodiment may contain various additives and fillers other than the above-mentioned polyesters, ethylene (co)polymers, and propylene (co)polymers, such as heat stabilizers, antioxidants, light stabilizers, antistatic agents, antiblocking agents, lubricants, nucleating agents, flame retardants, pigments, dyes, calcium carbonate, barium sulfate, magnesium hydroxide, mica, talc, clay, antibacterial agents, and anti-fogging agents, provided that the addition does not conflict with the objectives of the present invention. Furthermore, other thermoplastic resins, thermoplastic elastomers, rubbers, and the like may also be blended within the scope of the present invention.

Easy-to-open film The heat-sealable film of this embodiment is a polymer film having the above-mentioned heat-sealable properties and a coating layer formed on the surface thereof, and can be used alone as a heat-sealable film. However, the heat-sealable film of this embodiment may also be used as a heat-sealable layer in combination with other layers to form a laminated film.
A laminated film formed by using the heat-sealable film of this embodiment as the heat-sealable layer (A) and laminating this with the intermediate layer (B) and the laminate layer (C) can be preferably used as an easy-open film, etc. That is, an easy-open film formed by laminating the heat-sealable layer (A) made of the heat-sealable film of this embodiment, the intermediate layer (B), and the laminate layer (C) in this order is one of the particularly preferred embodiments of the present invention.
Heat-sealing layer (A)
The heat-sealable layer (A) constituting the easy-open film of this embodiment is made of the heat-sealable film of the above embodiment, which has a coating layer formed on the surface of a heat-sealable polymer film. Therefore, the details of the heat-sealable layer (A) are the same as those described above for the heat-sealable film of the above embodiment, and the details of the polymer film and coating layer constituting the heat-sealable layer (A) are also the same as those described above for the above embodiment.

When the easy-open film of this embodiment is used, for example, as a lid for a packaging container for food or the like, the heat-sealable layer (A) can be placed on the packaging container body side and fused to the packaging container body. The heat-sealable layer (A) can be advantageously used in this type of usage because it provides excellent anti-fogging properties, easy-open properties, low blocking properties, etc. by using the heat-sealable film of this embodiment.

There is no particular limitation on the thickness of the heat-sealable layer (A), but from the viewpoint of sealing properties, it is preferably 1.5 μm or more, and particularly preferably 2 μm or more.
On the other hand, from the viewpoint of ease of opening, etc., the thickness is preferably 15 μm or less, and particularly preferably 10 μm or less.

Middle layer (B)
The components of the intermediate layer (B) constituting the easy-open film of the present embodiment are not particularly limited, but from the viewpoint of the strength, transparency, lightness, etc. of the easy-open film, it is preferable that it contains a polyolefin, and it is particularly preferable that it contains an ethylene (based) copolymer or a propylene (co)polymer.
Details of the ethylene (based) copolymer and propylene (co)polymer are the same as those described above with respect to the polymer film constituting the heat-sealable film of the above embodiment.
In addition, from the viewpoint of adhesion to the heat-sealing layer (A) and the laminate layer (C), the film may contain an acid-modified polyolefin resin, and more preferably an acid-modified polyethylene resin.

In the intermediate layer (B), an ethylene-based (co)polymer can also be preferably used, and preferred examples thereof include polyethylene resins such as very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), linear medium density polyethylene (LMDPE), and medium density polyethylene (MDPE), as well as ethylene-vinyl acetate copolymer (EVA), which may be used alone or in combination of two or more. Among these, LLDPE is preferred because of its good film-forming properties.
Preferred examples of acid-modified polyolefins include modified polymers obtained by copolymerizing (e.g., graft copolymerizing) polyolefins with unsaturated carboxylic acids or their derivatives. Examples of polyolefins include homopolymers of olefins, mutual copolymers (between olefins), and copolymers with other copolymerizable monomers (e.g., other vinyl monomers). Specific examples include polyethylene (LDPE, LLDPE, etc.), polypropylene, polybutene, mutual copolymers thereof, ionomer resins, ethylene-acrylic acid copolymers, ethylene-vinyl acetate copolymers, etc. Examples of unsaturated carboxylic acids or derivatives thereof include unsaturated carboxylic acids such as maleic acid and fumaric acid, their acid anhydrides, their esters, and their metal salts. Among these, maleic acid-modified polyolefins are preferred.
The additives and the like that can be used in the intermediate layer (B) are the same as those explained above in relation to the polymer film used in the heat-sealable layer (A).

Of the layers constituting the easy-open film of this embodiment, the heat-sealing layer (A) is preferably designed to provide appropriate sealing properties, and the laminate layer (C) is preferably designed taking into consideration the lamination strength between it and the base film, while the intermediate layer (B) is preferably designed to provide adhesion between the heat-sealing layer (A) and the laminate layer (C).

The thickness of the intermediate layer (B) is preferably 2 μm or more, particularly preferably 3 μm or more.
On the other hand, the thickness of the intermediate layer (B) is preferably 45 μm or less, and particularly preferably 43 μm or less.

Laminate layer (C)
The laminate layer (C) constituting the easy-open film of the present embodiment can be laminated with other layers such as the substrate film described below, as necessary or desired.
Therefore, it is preferable to design the laminate layer (C) taking into consideration the lamination strength between the laminate layer (C) and other layers, including the substrate film. For example, it is preferable to use the same material as the substrate film and other layers, and therefore it is preferable to use a polyolefin-based material, which is preferably used for the substrate film. Depending on the type of substrate, polyester-based materials such as PET and polyamide-based materials such as nylon can also be used.
In order to further improve the laminate strength between the substrate and the like, the surface of the (C) laminate layer (the surface opposite to the surface to be laminated with the (B) intermediate layer) may be subjected to a corona treatment, a roughening treatment, or the like.

On the other hand, from the viewpoint of improving the lamination strength with the (B) intermediate layer, it is also preferable to use the same type of material as the (B) intermediate layer, more specifically polyolefin, more preferably ethylene polymer.
The additives and the like that can be used in the laminate layer (C) are the same as those explained above in relation to the polymer film used in the heat-sealable layer (A).

When the intermediate layer (B) contains an ethylene-based polymer, the laminate layer (C) preferably also contains an ethylene-based polymer, particularly preferably a linear low-density polyethylene, from the viewpoint of lamination strength with the intermediate layer (B).
The content in this case is not particularly limited, but the content of the ethylene polymer in the (C) laminate layer is preferably 50% by mass or more, more preferably 60 to 99.9% by mass, and particularly preferably 80 to 99.9% by mass.

From the viewpoint of preventing blocking during storage of the easy-open film of this embodiment, the laminate (C) layer may contain an anti-blocking agent.
As the anti-blocking agent, powdered silica, preferably synthetic silica, etc. can be suitably used. From the viewpoint of uniformly dispersing the powdered silica in the laminate layer (C), the powdered silica may be dispersed in a resin having excellent miscibility with the material constituting the laminate layer (C), for example, in low-density polyethylene, to form a masterbatch, and then the masterbatch may be added to the material constituting the laminate layer (C).

There are no particular restrictions on the thickness of the laminate layer (C), but from the viewpoint of lamination strength, etc., it is preferably 1.5 μm or more, and particularly preferably 2 μm or more.
The thickness of the laminate layer (C) is preferably 20 μm or less, and particularly preferably 15 μm or less.

As described above, the easy-open film of this embodiment has a heat-sealing layer (A), an intermediate layer (B), and a laminate layer (C). In the laminate film of this embodiment, the laminate layer (C) and the heat-sealing layer (A) are preferably laminated via the intermediate layer (B), but other layers may also be present; for example, an adhesive layer may be interposed between the heat-sealing layer (A) and the intermediate layer (B).

The easy-open film of this embodiment can be produced by various known film forming methods, such as a method in which films to become the laminate layer (C), intermediate layer (B), and heat-sealing layer (A) are first formed, a coating layer is formed on the heat-sealing layer (A), and these films are then bonded together to form a laminated film; a method in which a multilayer film consisting of an intermediate layer (B) and a heat-sealing layer (A) is obtained using a multilayer die, a laminate layer (C) is extruded onto the surface of the intermediate layer (B) to form a laminated film, and a coating layer is then formed on the heat-sealing layer (A); a method in which a multilayer film consisting of a laminate layer (C) and an intermediate layer (B) is obtained using a multilayer die, a heat-sealing layer (A) is extruded onto the surface of the intermediate layer (B) to form a laminated film, and a coating layer is then formed on the heat-sealing layer (A); or a method in which a laminate film consisting of a laminate layer (C), intermediate layer (B), and heat-sealing layer (A) is obtained using a multilayer die, and a coating layer is then formed on the heat-sealing layer (A).

As the film forming method, various known film forming methods, specifically, T-die cast film forming method, inflation film forming method, etc. can be adopted.
The easy-open film of the embodiment and each layer constituting the film may be a non-stretched film (unstretched film) or a stretched film.

The thickness of the easy-open film of this embodiment is not particularly limited, but from the viewpoint of ensuring practical strength, it is usually 10 μm or more, preferably 15 μm or more, and more preferably 20 μm or more. On the other hand, from the viewpoint of maintaining practical flexibility even after being laminated with, for example, a base film, it is usually 100 μm or less, preferably 80 μm or less, and more preferably 70 μm or less.

The easy-open film of the present embodiment may be a stretched film or a non-stretched film, but from the viewpoint of improving mechanical properties, it is preferably a stretched film, and particularly preferably a biaxially stretched film.
As the biaxial stretching method, a method such as sequential biaxial stretching, simultaneous biaxial stretching, or multi-stage stretching is suitably adopted.
The conditions for biaxial stretching may be those for producing known biaxially stretched films. For example, in the case of a sequential biaxial stretching method, the longitudinal stretching temperature may be set to 100°C to 145°C, the stretching ratio may be set to a range of 4 to 7 times, and the transverse stretching temperature may be set to 150°C to 190°C, and the stretching ratio may be set to a range of 8 to 11 times.

Substrate Film If desired, the easy-open film of the present embodiment can be laminated with a substrate film, preferably at its laminating layer (C).

There are no particular limitations on the base film, and for example, films that are normally used for plastic packaging can be suitably used.
Preferred materials for the substrate film include plastic films made of thermoplastic resins such as polyolefins such as crystalline polypropylene, crystalline propylene-ethylene copolymer, crystalline polybutene-1, crystalline poly-4-methylpentene-1, low-, medium-, or high-density polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and ionically crosslinked olefin copolymers (ionomers); aromatic vinyl copolymers such as polystyrene and styrene-butadiene copolymer; halogenated vinyl polymers such as polyvinyl chloride and vinylidene chloride resin; nitrile polymers such as acrylonitrile-styrene copolymer and acrylonitrile-styrene-butadiene copolymer; polyamides such as nylon 6, nylon 66, and para- or meta-xylylene adipamide; polyesters such as polyethylene terephthalate (PET) and polytetramethylene terephthalate; various polycarbonates; and polyacetals such as polyoxymethylene. Furthermore, when the contents to be packaged are oxygen-sensitive, the above film may be provided with a film vapor-deposited with a metal oxide or the like, a film coated with an organic compound, or a layer made of ethylene vinyl alcohol copolymer (EVOH) resin.
Plastic films made of these materials are used in an unstretched, uniaxially stretched, or biaxially stretched state.

As the base film, these plastic films can be used as a single layer or as a laminate of two or more types, and they can also be constructed by laminating one or two or more types of these plastic films with metal foil such as aluminum, paper, cellophane, etc.
Preferred substrate films include, for example, single-layer films made of stretched nylon film or stretched polyester film, two-layer films made by laminating a polyolefin film such as low-density polyethylene or polypropylene with PET, and three-layer films made by laminating PET/nylon/polyethylene. When producing these laminated films, adhesives or anchoring agents can be interposed between the layers as needed. An ink layer for displaying a design can also be provided.

The method for laminating the substrate layer to the laminate layer (C) or the like is not particularly limited, but for example, the substrate film can be directly laminated to the laminate layer (C) by extrusion lamination or the like. Alternatively, the substrate film may be laminated to the laminate layer (C) via an adhesive by dry lamination or the like. As the adhesive, a conventional adhesive such as a urethane-based adhesive, an acid-modified polyolefin-based adhesive, a polyester-based adhesive, a polyether-based adhesive, or a polyamide-based adhesive can be used.
The thickness of the substrate film can be set arbitrarily, but can usually be selected within the range of 7 to 500 μm, preferably 7 to 50 μm.

The laminated film obtained by laminating a substrate film to the laminate layer (C) of the easy-open film of this embodiment is preferably used in various applications, and is particularly suitable for use as a packaging material such as an easy-open film.
A preferred example of such a packaging material is a lid material. That is, a laminated film obtained by laminating a base film on the laminate layer (C) of the easy-open film of the present embodiment can be used as a lid material for a container in which the heat-sealable layer (A) is used as the innermost layer on the container side, taking advantage of its easy-open properties, etc.
When used as a container lid material, the heat-sealable film of the present invention may be used as the lid material as it is, or may be printed before use. Furthermore, it may be laminated to a printed or unprinted base film to form a lid material. Depending on the application, it may also be cut in advance to fit the shape of the container to form a lid material. When used as a container lid material, it is preferable to laminate it to a base film.
By combining a lid material having the above-mentioned easy-open film with a container, an easy-open package can be formed.

The easy-open film of this embodiment can form a heat-sealable layer by heat-sealing the heat-sealable layer (A) to various adherends. Examples of such adherends include propylene polymers, polystyrene, polyester, polycarbonate, polyvinyl chloride, etc. These adherends can be in various shapes, such as films, sheets, trays, cups, and bottles. Of these, polyester is particularly preferred as the adherend, as it provides excellent sealing properties, easy opening, heat resistance, oil resistance, etc. of the heat-sealable layer.

While there are no particular restrictions on the items that can be stored in the packaging container, it can be preferably used to package food, pharmaceuticals, medical equipment, daily necessities, miscellaneous goods, etc. Taking advantage of the excellent visibility, anti-fogging properties, heat seal strength (easy opening), and low blocking properties of the heat-sealable film of the present invention, it is particularly suitable for use as a packaging container for prepared foods, salads, fruit, etc.

The present invention will be specifically explained below with reference to examples and comparative examples. However, the present invention is not limited in any way by the following examples.

The physical properties and characteristics in the examples and comparative examples were evaluated by the following methods.
(Reflective IR spectrum)
The coating composition was applied to a polyethylene terephthalate film having a thickness of 12 μm, and the film was dried by heating at 80° C. for 20 seconds to prepare a sample having a coating having a thickness of approximately 2 μm after drying. The reflection IR spectrum of the coated surface was measured using an IRT-5200 instrument manufactured by JASCO Corporation under the following conditions.
Measurement cell: Ge
Incident angle: 45°
Resolution: 4cm ^-1
Accumulation count: 100 times

(Melting point peak)
The endothermic peak in the second temperature rise of the coating composition was measured according to a conventional method for measuring the melting point by DSC. The apparatus and measurement conditions are shown below.
Apparatus: X-DSC7000 manufactured by SII (Seiko Instruments Inc.)
First temperature increase: The temperature was increased from normal temperature of 30°C to 150°C at a rate of 10°C/min.
Holding: Holding at 150°C for 1 minute.
Cooling: Cool to -100°C at 10°C/min. Hold for 1 minute. Second heating: Heat to 150°C at a rate of 10°C/min and hold for 1 minute.

(Coating amount)
The coating weight of the coating layer was evaluated by gravimetric measurement.
The sample on which the coating layer was formed was cut into a 10 cm x 10 cm piece and its weight was measured. The coated surface was then cleaned using a Kimwipe wetted with ethanol. The weight of the sample after cleaning was measured, and the difference in weight before and after cleaning was taken as the coating amount. The weight difference was then divided by the area to convert it into g/ ^m² .

(Anti-fogging properties)
30 mL of purified water was placed in a transparent beaker, covered with the sample film with the measurement surface (coated surface) facing inward (water side), and stored in a refrigerator (set at approximately 5° C.) After 24 hours of storage, the film was removed from the refrigerator and the degree of cloudiness of the film immediately after removal was visually observed and rated on a 5-point scale, with 5 points for no cloudiness and 1 point for cloudy and opaque.
FIG. 1(a) shows a schematic diagram of the evaluation criteria, and FIG. 1(b) shows a photograph of an actual example of anti-fogging evaluation.

(Blocking strength)
Two sample films were stacked with the coated surface and the uncoated surface in contact, and after storing at 40°C and under a pressure of 4 kg for 24 hours, the peel strength (N/5.2 cm ² ) of the two sample films was measured using a universal tensile tester (manufactured by A&D Co., Ltd.).

(Heat seal strength)
The coated surface of the sample film was placed on an A-PET sheet (softening point 77°C, crystallization temperature 126°C) in the case of heat-sealable substrate 1, or on a PP sheet (main melting point 162.9°C, sub-melting point 107.5°C) in the case of heat-sealable substrates 2 and 3. The sample was heat-sealed for 1.0 second using a precision heat sealer (manufactured by Tester Sangyo) at a temperature of 120 to 180°C and a pressure of 0.2 MPa with a 5 mm wide seal bar, and then allowed to cool. A 15 mm wide test piece was then cut from the heat-sealed sample, and the maximum load was measured by peeling it off in a 180° direction using a universal tensile tester (manufactured by A&D Co., Ltd.) at a tensile speed of 300 mm/min in a thermostatic chamber at 23°C and 50% RH (unit: N/15 mm).

Details of the materials/components used in the examples/comparative examples are as follows:
Heat-adhesive base material

・Heat-fusible base material 1
A laminated film having a three-layer structure and a thickness of 30 μm, consisting of a heat-sealing layer, an intermediate layer and a laminate layer, each having a thickness of 5.1 μm, 6.3 μm and 18.6 μm, was used as the substrate film.
The resins constituting each layer were as follows:
Heat-sealing layer: polyethylene terephthalate resin (Tg: 73°C, density: 1340 kg/m ³ )
Intermediate layer: Polyolefin resin (MFR (2.16 kg 190°C): 5.6 g/10 min, density: 903 kg/m ³ )
Laminate layer: polyethylene resin (MFR (2.16 kg 190°C): 3 g/10 min, density: 928 kg/m ³ , melting point: 114°C)

・Heat-fusible base material 2
A laminated film having a three-layer structure and a thickness of 30 μm, consisting of a heat-sealable layer/an intermediate layer/a laminate layer having thicknesses of 3.6 μm/21.9 μm/4.5 μm, respectively, was used as the heat-sealable substrate 2 .
The resins constituting each layer were as follows:
・Heat-sealing layer
Melt blend resin of ethylene copolymer + propylene random copolymer + tackifier Density: 925 kg/ ^m3
Melting point: 123.1°C (main), 143.0°C, 98.7°C, 85.2°C (sub)
Intermediate layer: Propylene homopolymer MFR (2.16 kg 230°C): 7 g/10 min Density: 910 kg/ ^m3
Melting point: 161°C
Laminate layer: Linear low-density polyethylene MFR (2.16 kg 190°C): 3.6 g/10 min Density: 909 kg/ ^m3
Melting point: 115°C

・Heat-fusible base material 3
A laminated film having a three-layer structure and a thickness of 30 μm, consisting of a heat-sealable layer/an intermediate layer/a laminate layer having thicknesses of 3.3 μm/23.4 μm/3.3 μm, respectively, was used as the heat-sealable substrate 3 .
The resins constituting each layer were as follows:
Heat-sealing layer: Melt blend resin of ethylene copolymer + propylene random copolymer + tackifier Density: 920 kg/ ^m3
Melting point: 126.2℃ (main) 142.6℃ (sub) ℃
- Intermediate layer: The same resin as the heat-sealing layer was used.
・Laminate layer
Propylene random copolymer MFR (2.16 kg 230°C): 7.3 g/10 min Density: 910 kg/ ^m3
Melting point: 143°C)

Polymer surfactant: Acrylic polymer surfactant 1 (aqueous solution with 15% solid content, acrylic polymer containing quaternary ammonium salt, molecular weight approximately 26,000, acid value 1.0, melting point: 118° C.) was used.

Low molecular weight surfactant: Low molecular weight surfactant 1 (diglycerin monolaurate, molecular weight: 349) was used.

Preparation and Evaluation of Coating Composition (Comparative Example 1)
Low molecular weight surfactant 1 was dispersed in a solvent (a mixed solvent of isopropanol and water) to prepare a coating composition with a concentration of 2% by mass.
The reflective IR spectrum and melting point peak of the coating composition were evaluated according to the above-mentioned methods, and the results are shown in Table 1.

(Examples 1 to 4)
Low molecular weight surfactant 1 and polymeric surfactant 1 were mixed in the mass ratio shown in Table 1 and dispersed in a solvent (a mixed solvent of isopropanol and water) to prepare a coating composition with a concentration of 2 mass %.
The reflective IR spectrum and melting point peak of the coating composition were evaluated according to the above-mentioned methods, and the results are shown in Table 1.

Coating Application and Evaluation (Blank 1)
For comparison, the heat-fusible substrate 1 that had not been coated was evaluated for anti-fogging properties, blocking strength, and heat seal strength according to the above methods.
The results are shown in Table 2.
Because no coating was applied, the anti-fogging properties were poor.

(Comparative Test 1-1)
The coating composition of Comparative Example 1 was applied to the heat-sealable layer side of the heat-sealable substrate 1 using a bar coater, and dried for 1 minute in a thermostatic chamber adjusted to 80°C to obtain a film in which a coating layer was formed on the heat-sealable layer of the heat-sealable substrate 1. The coating amount was calculated from the mass after drying and was found to be 0.2 g/ ^m2 .
The obtained film was evaluated for anti-fogging property, blocking strength, and heat seal strength according to the methods described above. The results are shown in Table 2.
The anti-fogging properties were excellent and the heat seal strength was adequate, but blocking occurred.

(Tests 1-1 to 1-8, Comparative Test 1-2)
The coating compositions of Examples 1 to 3 and Comparative Example 2 shown in Table 1 were applied to the surface of the heat-fusible substrate 1 on the heat-fusible layer side using a bar coater so as to obtain the coating amounts shown in Table 1, and then dried for 1 minute in a thermostatic oven adjusted to 80°C, thereby obtaining a film in which a coating layer was formed on the heat-fusible layer of the substrate film.
The obtained film was evaluated for anti-fogging property, blocking strength, and heat seal strength according to the methods described above. The results are shown in Table 2.
When the coating composition of each Example was used, the anti-fogging property, heat sealability, and blocking resistance were all good. When the coating composition of Comparative Example 2 was used, the heat seal strength was insufficient.

(Blank 2)
For comparison, the anti-fogging property and blocking strength of the uncoated heat-fusible substrate 2 were evaluated according to the above methods.
The results are shown in Table 3.
Because no coating was applied, the anti-fogging properties were poor.

(Comparative Test 2-1)
The coating composition of Comparative Example 1 was applied to the surface of the heat-fusible substrate 2 on the heat-fusible layer side using a bar coater, and dried for 1 minute in a thermostatic chamber adjusted to 80°C to obtain a film in which a coating layer was formed on the heat-fusible layer of the heat-fusible substrate 2. The coating amount was calculated from the mass after drying and was found to be 0.050 g/ ^m2 .
The anti-fogging properties and blocking strength of the obtained film were evaluated according to the methods described above. The results are shown in Table 3.
In comparison with any of Test Examples 2-1 to 2-4 described later, at least one of the anti-fogging property and the blocking resistance was inferior.

(Tests 2-1 to 2-3, Comparative Test 2-2)
A film in which a coating layer was formed on the heat-fusible layer of the heat-fusible substrate 2 was obtained in the same manner as in Comparative Test 2-1, except that the coating composition of Comparative Example 1 was changed to the coating compositions of Examples 1 to 3 and Comparative Example 2 shown in Table 3. The coating amount was calculated from the mass after drying and was found to be 0.050 g/ ^m2 .
The anti-fogging properties and blocking strength of the obtained film were evaluated according to the methods described above. The results are shown in Table 3.
When the coating composition of each Example was used, the balance of anti-fogging properties, heat sealing properties, and blocking resistance was excellent compared to Comparative Test 2-1. When the coating composition of Comparative Example 2 was used, the anti-fogging properties were insufficient.

(Blank 3)
For comparison, the anti-fogging property and blocking strength of the uncoated heat-fusible substrate 3 were evaluated according to the above methods.
The results are shown in Table 4.
Because no coating was applied, the anti-fogging properties were poor.

(Tests 3-1 and 3-2)
The coating composition of Example 2 was applied to the surface of the heat-fusible substrate 3 on the heat-fusible layer side using a bar coater so as to obtain the coating amount shown in Table 4, and the coating was dried for 1 minute in a thermostatic bath adjusted to 80°C, thereby obtaining a film in which a coating layer was formed on the heat-fusible layer of the heat-fusible substrate 1.
The anti-fogging properties and blocking strength of the obtained film were evaluated according to the methods described above. The results are shown in Table 4.
The film had an excellent balance of anti-fogging properties, heat sealing properties, and blocking resistance.

The coating composition of the present invention can form a coating layer that combines highly practically valuable properties, such as anti-fogging properties, heat seal strength (easy opening), and low blocking properties, at a high level that surpasses the limits of conventional technology.The coating composition of the present invention can be suitably used in a variety of applications, including lids for easy-open plastic containers that store various products, such as food, that require visibility of the contents, and has high applicability in various fields of industries such as food processing, distribution, retail, and restaurant services.

Claims (9)

(a) a low molecular weight surfactant; and (b) a polymer surfactant,
In reflection IR spectrum measurement, the ratio (P4/P2) of the absorption peak height (P2) at 1730 cm ⁻¹ ±30 cm ⁻¹ to the absorption peak height (P4) at 1560 cm −1 ±30 cm ⁻¹ is 0.08 or more and 1.80 or less,
A coating composition having a ratio (P3/P2) of an absorption peak height (P2) at 1730 cm ⁻¹ ±30 cm ⁻¹ to an absorption peak height (P3) at 1630 cm −1 ±30 cm ⁻¹ of 0.03 or more and 0.60 or less. 2. The coating composition according to claim 1, wherein, in a reflection IR spectrum measurement, the ratio (P1/P2) of the absorption peak height (P2) at 1730 cm ⁻¹ ±30 cm ^{−1 to} the absorption peak height (P1) at 3400 cm −1 ±30 cm −1 is 0.10 or more and 0.58 or less. 3. The coating composition according to claim 1 , which has a melting point peak at 35±25°C in DSC measurement. The coating composition according to claim 3 , further having melting point peaks at 15.3±5°C and 118±15°C in DSC measurement. The coating composition of claim 1 , wherein (a) the low molecular weight surfactant comprises a nonionic surfactant. The coating composition according to claim 1 or 5 , wherein the polymer surfactant (b) comprises an acrylic surfactant. 7. An easily openable film comprising a heat-sealable layer (A), an intermediate layer (B), and a laminate layer (C) laminated in this order, and having a coating layer formed from the coating composition according to claim 1 on the heat-sealable layer (A). The easy-open film according to claim 7 , wherein the heat-sealable layer (A) contains at least one of polyethylene terephthalate, an ethylene-based (co)polymer, and a propylene-based (co)polymer. An easy-open package comprising a lid material having the easy-open film according to claim 7 or 8 , and a container.