JP2016199029A - Antifogging sheet and container, and fine particle adhesion preventing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antifogging sheet capable of preventing fine particles such as chips generated by molding processing from adhering onto the surface.SOLUTION: An antifogging layer having a minus frictional charge potential is laminated on one surface of a substrate layer containing a thermoplastic resin, and a release layer having a minus frictional charge potential and surface resistivity of 2×10Ω or less is laminated on the other surface of the substrate layer. The release layer may contain a mold release agent (a) and an anionic surfactant (b). The antifogging layer may contain a nonionic surfactant (A) and an anionic surfactant (B). The frictional charge potential of the release layer may be -0.1 kV or less. A surface resistivity of the antifogging layer may be 2×10Ω or less.SELECTED DRAWING: None

Description

  The present invention relates to an antifogging sheet used for food containers and the like, a container formed of the antifogging sheet, and fine particles such as chips and dust generated in the sheet punching process. It is related with the method of preventing adhering to the surface of.

  Hydrophobic synthetic resin sheets such as styrene resin sheets are used for packaging containers such as foods, but have low antifogging properties. Therefore, when food or the like is stored in a container formed of the sheet, water vapor adheres to the surface of the container as a minute water droplet due to changes in temperature and humidity, resulting in cloudiness and lowering transparency. Therefore, a method for improving the antifogging property by antifogging (coating) the sheet surface using a higher fatty acid ester such as sucrose fatty acid ester as an antifogging agent is known.

  Furthermore, a method for improving the antifogging property by combining an antifogging agent with an antifogging aid such as a hydrophilic polymer has been proposed. For example, Japanese Patent Application Laid-Open No. 2004-315802 (Patent Document 1) Non-ether water-soluble polymers such as polyhydric alcohol fatty acid esters such as sugar fatty acid esters and acrylic acid polymers or salts thereof, vinylpyrrolidone homopolymers or copolymers, and polyoxyethylene-polyoxypropylene block copolymers A coated resin sheet having a coating layer (anti-fogging layer) in combination with a coalesced ether-based hydrophilic polymer such as a nonionic surfactant having an oxyethylene unit is disclosed. This covering resin sheet also improves releasability by forming protrusions on the surface of the covering layer. Furthermore, it is described that the release layer can contain an ether-based hydrophilic polymer having an oxyethylene unit in addition to silicone oil.

  However, in this coated resin sheet, fine particles are likely to adhere to the surface of the anti-fogging layer or the release layer, which is undesirable from the viewpoint of hygiene in applications such as food. In particular, when an antifogging-treated sheet (a sheet having an antifogging layer or an antifogging sheet) is used for a food packaging container or the like, the antifogging sheet having a tray portion formed in the vertical and horizontal directions is usually punched. However, the chips generated in the sheet punching process are likely to adhere to the surface. In this sheet, such chips are particularly likely to adhere.

  In JP-A-2002-86639 (Patent Document 2), one surface of a styrene resin sheet is coated with an antifogging agent comprising a fatty acid ester such as a sucrose fatty acid ester, an ether multimer, and polyvinyl alcohol. The other surface is composed of an ether-based multimer and a surfactant selected from polyoxyethylene glycerin fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene aliphatic alcohol ethers, and fatty acid amides. A styrenic resin antifogging sheet coated with a release agent is disclosed.

  However, even with this anti-fogging sheet, chips adhere to the surface. Furthermore, since this anti-fogging sheet has a high surface resistivity, static electricity is easily accumulated and charged, and fine particles such as dust are likely to adhere to the surface.

  JP 2010-37387 A (Patent Document 3) discloses an anti-fogging surface treatment comprising a nonionic surfactant, a water-soluble polymer, and an anionic surfactant on at least one surface of a resin sheet. An antifogging resin sheet in which an antifogging layer containing an agent is formed and a release layer is formed on the other surface is disclosed. It is described that the release layer can be composed of a release agent such as silicone oil and an ether-based hydrophilic polymer (nonionic surfactant) having an oxyethylene unit. In the example of this document, no release layer is formed.

  However, even with this anti-fogging sheet, chips adhere to the surface. In addition, these patent documents 1 to 3 do not describe adhesion of fine particles such as chips and dust.

JP 2004-315802 A (Claims, paragraph [0079]) JP 2002-86639 A (Claims) JP 2010-37387 A (Claims)

  Accordingly, an object of the present invention is to provide an antifogging sheet capable of preventing fine particles such as chips generated by molding processing from adhering to the surface, a container formed of the antifogging sheet, and a method for preventing the adhesion of fine particles. There is.

  Another object of the present invention is to provide an antifogging sheet having high antistatic properties and capable of preventing fine particles such as dust from adhering to the surface, a container formed of the antifogging sheet, and a method for preventing the adhesion of fine particles. It is in.

  Still another object of the present invention is to provide an antifogging sheet that can prevent adhesion of fine particles and that is also excellent in antifogging property and releasability (antiblocking property), and a container formed of the antifogging sheet. It is in.

  Another object of the present invention is to provide an antifogging sheet having a uniform surface and a container formed of the antifogging sheet.

  Still another object of the present invention is to provide an antifogging sheet capable of maintaining a uniform surface even after secondary processing (secondary molding) and a container formed of the antifogging sheet.

As a result of intensive studies to achieve the above object, the present inventor laminated an antifogging layer having a negative triboelectric potential on one surface of a base material layer containing a thermoplastic resin, and By laminating a release layer having a negative triboelectric potential and a surface resistivity of 2 × 10 ¹³ Ω or less on the other surface, fine particles such as chips generated by molding process adhere to the surface. As a result, the present invention has been completed.

That is, the antifogging sheet of the present invention comprises a base material layer containing a thermoplastic resin, an antifogging layer laminated on one surface of the base material layer and having a negative triboelectric potential, and the base material layer. A release layer is included which is laminated on the other surface and has a negative triboelectric potential and a surface resistivity of 2 × 10 ¹³ Ω or less. The release layer may contain a release agent (a) and an anionic surfactant (b). The antifogging layer may contain a nonionic surfactant (A) and an anionic surfactant (B). The antifogging layer may further contain a hydrophilic polymer (C). The antifogging layer may further contain a release agent (D). The antifogging layer may further contain a metal ion (E). The release layer may further contain a metal ion (c). The anionic surfactant (b) of the release layer and the anionic surfactant (B) of the antifogging layer are the same or different, and are sulfonate, carboxylate, sulfate ester, phosphate and It may be at least one selected from the group consisting of phosphate ester salts. About 99.9 / 0.1-30 / 70 may be sufficient as the weight ratio of the said mold release agent (a) and the said anionic surfactant (b). The weight ratio of the nonionic surfactant (A) and the anionic surfactant (B) may be about 99/1 to 30/70. The triboelectric charging potential of the release layer may be −0.1 kV or less. The antifogging layer may have a surface resistivity of 2 × 10 ¹³ Ω or less. The base material layer may be a biaxially stretched styrene resin sheet.

The present invention also includes a container formed of the antifogging sheet. In the present invention, an antifogging layer having a negative triboelectric charge potential is laminated on one surface of a base material layer containing a thermoplastic resin, and a negative triboelectric charge is formed on the other surface of the base material layer. A method of preventing fine particles from adhering to the surface of the antifogging sheet by laminating a release layer having a potential and a surface resistivity of 2 × 10 ¹³ Ω or less is also included. The fine particles may be chips generated by molding an antifogging sheet. This forming process may be a punching process of an antifogging sheet in which the tray portions are formed adjacent to each other in the vertical and / or horizontal direction.

In the present invention, an antifogging layer having a negative triboelectric charge potential is laminated on one surface of a base material layer containing a thermoplastic resin, and a negative triboelectric charge potential on the other surface of the base material layer, Since the release layer having a surface resistivity of 2 × 10 ¹³ Ω or less is laminated, it is possible to prevent fine particles such as chips generated by molding processing from adhering to the surface. Furthermore, when the surface resistivity of the antifogging layer is adjusted to 2 × 10 ¹³ Ω or less, the antistatic property can be improved and fine particles such as dust can be prevented from adhering to the surface. In particular, when the antifogging layer and the release layer are formed of specific components, the adhesion of such fine particles can be prevented, and the antifogging property and the release property (anti-blocking property) can be improved. Therefore, an anti-fogging sheet and a container can be manufactured by a roll-to-roll method, and productivity can be improved. Further, when the antifogging layer and the release layer contain metal ions, the coating property can be improved in the production process, and a uniform surface (excellent coating appearance) can be formed. In particular, by adjusting the ratio of metal ions, an excellent coating appearance can be realized, and a uniform surface can be formed by a simple method regardless of the type of coating method. Furthermore, when the anti-fogging layer and the release layer contain metal ions, the anti-fogging sheet and the release layer of the anti-fogging sheet and the release layer can be formed by stretching or transfer even if the anti-fogging sheet is subjected to secondary processing (container molding or stretching molding by thermoforming) A decrease in uniformity can be suppressed, and a uniform surface (surface state or surface shape) can be maintained. Therefore, the antifogging sheet can suppress a decrease in antifogging property due to secondary processing, for example.

[Base material layer]
The antifogging sheet of the present invention includes a base material layer. The base layer is a thermoplastic resin such as a resin sheet having molding processability, particularly a hydrophobic synthetic resin sheet, such as an olefin resin (particularly polypropylene resin), a polyester resin (particularly polyethylene terephthalate resin), or a styrene resin. Can be made of resin. In particular, a resin sheet having high moldability, for example, a styrene resin sheet is preferable.

  Styrenic resins include homopolymers containing aromatic vinyl monomers (such as styrene, vinyltoluene, and α-methylstyrene) as constituents, and copolymerization of aromatic vinyl monomers and copolymerizable monomers. Combinations and mixtures thereof are included. More specifically, examples of the styrene resin include non-rubber reinforced styrene resin [polystyrene (GPPS) for general use, styrene- (meth) acrylic acid copolymer, styrene-methyl methacrylate copolymer (MS resin). ), Acrylonitrile-styrene copolymer (AS resin), acrylonitrile-styrene-methyl methacrylate copolymer, etc.], rubber-containing styrene resin [rubber reinforced polystyrene (high impact polystyrene: HIPS), styrene-diene block copolymer] Or its hydrogenated product (polystyrene-polybutadiene-polystyrene block copolymer, etc.), acrylonitrile-butadiene-styrene copolymer (ABS resin), rubber component X (acrylic rubber, chlorinated polyethylene, ethylene-propylene rubber (EPDM), Ethylene-vinegar Vinyl copolymer, etc.) and acrylonitrile A and styrene S is like AXS resin obtained by graft polymerization. These styrenic resins can be used alone or in admixture of two or more. The styrene resin sheet is a highly transparent styrene resin sheet (for example, a non-rubber reinforced styrene resin sheet composed of a non-rubber reinforced styrene resin such as GPPS, a styrene resin and a styrene-diene block copolymer). A styrene resin sheet composed of a coalescence or a hydrogenated product thereof, or a rubber-reinforced styrene resin sheet.

  The base layer is made of various additives such as stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, etc.), antistatic agents, crystal nucleating agents, hydrocarbon polymers, plasticizers, mineral oils, It may contain a filler, a colorant and the like.

  The substrate layer can be obtained by a conventional method, for example, a conventional film forming method such as a T-die method or an inflation method. The base material layer may be unstretched, but is preferably stretched. The stretched film may be a uniaxially stretched film, but is preferably a biaxially stretched film. Moreover, you may heat-process (heat-setting process) a stretched film as needed. Examples of the stretching method include conventional stretching methods such as roll stretching, roll stretching, belt stretching, tenter stretching, tube stretching, and stretching methods combining these. The draw ratio can be appropriately set according to the desired sheet properties, and may be, for example, 1.2 to 20 times, preferably 1.5 to 15 times, and more preferably about 2 to 10 times.

The surface of the base material layer may be subjected to a conventional surface treatment such as corona discharge treatment or high frequency treatment. In particular, the surface of the base material layer (particularly the surface on the antifogging layer side) is preferably subjected to corona discharge treatment to form an antifogging layer on the corona discharge treatment surface. Although the surface tension of the base material layer varies depending on the type of sheet and cannot be determined unconditionally, it is 30 to 65 dyn / cm (30 × when measured in accordance with JIS K6768 “wetting test method for polyethylene and polypropylene film”). 10 ^{−5 to} 65 × 10 ⁻⁵ N / cm). In the case of a styrene resin sheet, the surface tension is 40 to 62 dyn / cm (40 × 10 ^{−5 to} 62 × 10 ⁻⁵ N / cm), preferably 42 to 62 dyn / cm (42 × 10 ^{−5 to} 62 × 10 ^{− 5} N / cm), more preferably about 45 to 60 dyn / cm (45 × 10 ^{−5 to} 60 × 10 ⁻⁵ N / cm).

  If the surface tension on the surface of the base material layer is too high, the surface of the base material layer is excessively activated, or the blocking becomes easy. Therefore, it becomes difficult to rewind a sheet wound in a roll shape, or when a plurality of molded containers are stacked and punched out, the containers are brought into close contact with each other, and the work efficiency of separating the containers and storing the contents decreases. easy.

[Anti-fogging layer]
An antifogging layer is laminated on one surface of the base material layer. The antifogging layer has a negative frictional charging potential (friction charging potential sign) from the viewpoint of preventing adhesion of fine particles (particularly chips). The triboelectric charging potential of the antifogging layer may be a negative potential, but may be, for example, less than 0 kV (for example, −0.1 to −10 kV), preferably −0.3 to −8 kV, and more preferably − It may be about 0.3 to -6 kV. In the present invention, the triboelectric potential can be measured by the method described in the examples described later in accordance with JIS C61340-2-2.

The anti-fogging layer may have a surface resistivity of 2 × 10 ¹³ Ω or less, for example, 1 × 10 ⁷ to 1 × 10 ¹³ Ω, preferably 1 × from the viewpoint of preventing adhesion of fine particles (particularly dust). It is about 10 ^{8 to} 7 × 10 ¹² Ω, more preferably about 1 × 10 ^{9 to} 5 × 10 ¹² Ω. In the present invention, the surface resistivity can be measured by a method described in Examples described later in accordance with JIS K6911.

(A) Nonionic surfactant The antifogging layer contains a nonionic surfactant (A). Nonionic surfactants (A) can be broadly classified into polyhydric alcohol fatty acid esters and adducts obtained by adding ethylene oxide to active hydrogen atoms of hydrophobic compounds. In the present invention, the nonionic surfactant (A) is used to mean that it does not include the polyoxyethylene-polyoxypropylene copolymer exemplified by the hydrophilic polymer (C) described later.

Examples of the polyhydric alcohol include C _2-12 alkylene glycols such as ethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol; diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, and polypropylene. (Poly) oxy C _2-4 alkylene glycol such as glycol and polytetramethylene glycol; glycerin, polyglycerin having a polymerization degree of about 2 to 20 (diglycerin, triglycerin, tetraglycerin, polyglycerin, etc.), trimethylolethane, triglyceride Methylolpropane, pentaerythritol, saccharides (sucrose, sorbitol, mannitol, xylitol, maltitol, sorbitan, ori Sugar, etc.) polyhydroxy compounds, such as (polyhydric alcohols), and others. These polyhydric alcohols can be used alone or in combination of two or more.

The fatty acid may be either a monocarboxylic acid or a polyvalent carboxylic acid, and may be either a saturated or unsaturated fatty acid. The fatty acid includes a component containing a fatty acid, for example, a component containing a fatty acid as a main component (for example, containing 50% by weight or more) (for example, fats and oils such as coconut oil). Fatty _{acids, C 6-40} fatty acids, preferably _{C 8-30} fatty acids (e.g., capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, hydroxy stearic acid, arachidic acid, behenic acid, _{C 8,} such as montanic acid _-26 saturated fatty acids, oleic acid, _{C 8-26} unsaturated fatty acids such as erucic acid), more preferably _{C 10-22} saturated fatty acids _{(e.g., C 10-20} saturated fatty acids), in particular _{C 10-18} saturated fatty acids ( It may be a saturated fatty acid such as lauric acid, myristic acid, palmitic acid or stearic acid or a mixture thereof (such as coconut oil fatty acid) or an unsaturated fatty acid such as oleic acid).

  The polyhydric alcohol fatty acid ester is often selected from sucrose fatty acid ester, glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitol fatty acid ester, and sorbitan fatty acid ester.

Examples of sucrose fatty acid esters include sucrose laurate (such as sucrose mono- to penta-laurate), sucrose palmitate (such as sucrose mono- to pentapalmitate), and sucrose stearate (sucrose). Sucrose C _8-24 such as sugar mono to pentastearate, sucrose behenate (sucrose mono to pentabehenate, etc.), sucrose oleate (sucrose mono to pentaoleate, etc.) Saturated or unsaturated fatty acid esters (mono to hexaesters etc.), especially sucrose C _8-24 saturated or unsaturated fatty acid esters (mono to tetraesters etc.), etc. may be mentioned.

Examples of glycerin fatty acid esters include esters of glycerin and C _8-24 saturated or unsaturated fatty acids, such as glycerin caprylic acid esters (such as glycerin mono to dicaprylic acid esters), glycerin lauric acid esters (such as glycerin mono to dilauric acid esters). ), Glycerin stearic acid ester (such as glycerin mono to distearic acid ester), glycerin behenic acid ester (such as glycerin mono to dibehenic acid ester), glycerin oleic acid ester (such as glycerin mono to dioleic acid ester) and the like.

Examples of the polyglycerin fatty acid ester include esters of polyglycerin having a polymerization degree of about 2 to 16 and a C _8-24 saturated or unsaturated fatty acid, such as decaglycerin caprylic acid ester (such as decaglycerin mono to decaprylic acid ester), hexa Glycerin laurate (such as hexaglycerin mono to hexalaurate), decaglycerin laurate (such as decaglycerol mono to decalaurate), decaglycerol stearate (such as decaglycerol mono to decastearate), deca Examples thereof include glycerin oleate (such as decaglycerin mono to dekaoleate).

Examples of sorbitol fatty acid esters include esters of sorbitol and C _8-24 saturated or unsaturated fatty acids, such as sorbitol caprylate (such as sorbitol mono to pentacaprylate), sorbitol laurate (sorbitol mono to pentalaurate). Ester), sorbitol palmitate (such as sorbitol mono to pentapalmitate), sorbitol stearate (such as sorbitol mono to pentastearate), sorbitol oleate (such as sorbitol mono to pentaoleate), and the like And sorbitan fatty acid esters corresponding to these fatty acid esters.

These fatty acid esters can be used alone or in combination of two or more. Preferred polyhydric alcohol fatty acid esters include sucrose fatty acid esters, polyglycerin fatty acid esters, glycerin fatty acid esters, sucrose fatty acid esters (sucrose lauric acid esters), because they are highly hydrophilic and easy to handle. Sucrose C _8-24 saturated fatty acid ester etc.) and / or polyglycerin fatty acid ester (polyglycerin C _8-24 saturated fatty acid ester etc. having a polymerization degree of about 4-12 such as hexaglycerin lauric acid ester). .

In the ethylene oxide adduct of a hydrophobic compound, examples of the hydrophobic compound having an active hydrogen atom include higher alcohols (such as C _8-24 alcohols such as lauryl alcohol), aromatic hydroxy compounds (such as phenols and alkylphenols). Examples thereof include polyhydric alcohol fatty acid esters having a hydroxyl group, and fats and oils having a hydroxyl group (such as castor oil and hydrogenated castor oil).

As an ethylene oxide adduct of a hydrophobic compound, for example, an ethylene oxide adduct of a higher alcohol (polyoxyethylene C _8-26 alkyl ether such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene octadecyl ether ( Preferably polyoxyethylene C _10-20 alkyl ether)), ethylene oxide adducts of aromatic hydroxy compounds [for example, polyoxyethylene aryl ethers such as polyoxyethylene phenyl ether (preferably polyoxyethylene C _6-10 aryl) ether, etc.); polyoxyethylene alkylaryl ethers such as polyoxyethylene nonylphenyl ether (preferably polyoxyethylene C _4-26 alkyl C _{6- 0} and aryl ether), etc.], a polyhydric ethylene oxide adduct of alcohol fatty acid esters [polyoxyethylene glycerin stearic acid ester, polyoxyethylene sorbitan stearic acid ester, a polyoxyethylene chain, such as polyoxyethylene sorbitol stearate C _8-26 fatty acid ester (preferably C _10-20 fatty acid ester having a polyoxyethylene chain) and the like, and an ethylene oxide adduct of fat (polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene palm) An ethylene oxide adduct of a hydroxyl group-containing oil such as oil). The number average molecular weight of the polyoxyethylene adduct is, for example, 150 or more (for example, 150 to 35,000), preferably 200 to 20,000, and more preferably about 200 to 10,000.

  In the present invention, the molecular weight can be measured by gel permeation chromatography (GPC) in terms of polystyrene.

  In the ethylene oxide adduct of a hydrophobic compound, the average addition mole number of oxyethylene units may be, for example, 2 to 100, preferably 2 to 50, more preferably about 3 to 30, or about 2 to 10. There may be.

  In the polyhydric alcohol fatty acid ester and its ethylene oxide adduct, the fatty acid is not limited to a single fatty acid but may be a plurality of fatty acids (mixed fatty acids).

A nonionic surfactant (A) may be comprised independently, and may be comprised combining several (same kind or different kind) surfactant. The nonionic surfactant (A) is at least one component selected from sucrose fatty acid ester, polyglycerin fatty acid ester, glycerin fatty acid ester and polyoxyethylene alkyl ether (such as polyoxyethylene C _10-20 alkyl ether). In particular, at least sucrose fatty acid ester (such as sucrose _C10-20 fatty acid ester such as sucrose laurate) is preferable.

  The nonionic surfactant (A) is solid at room temperature (for example, 20 to 25 ° C.) from the viewpoint that it can improve the antifogging property and can suppress the transfer to a roll (particularly a metal roll) and adhesion and set-off. Is preferred. The melting point or softening point of the nonionic surfactant is 50 ° C. or higher (for example, about 50 to 100 ° C.), preferably 60 ° C. or higher (for example, about 60 to 98 ° C.), more preferably 80 ° C. or higher (for example, 80 to 95). (Degree C).

  The ratio of nonionic surfactant (A) should just be about 10 weight% or more with respect to the whole anti-fogging layer, for example, 30-95 weight%, Preferably it is 40-90 weight%, More preferably, it is 50- It is about 85% by weight (particularly 60 to 80% by weight). If the proportion of the nonionic surfactant is too small, the antifogging property may be lowered.

(B) Anionic surfactant The antifogging layer further contains an anionic surfactant (B). In the present invention, by combining the anionic surfactant (B) with the nonionic surfactant (A), the triboelectric charge potential can be adjusted to a negative potential, or the adhesion of fine particles (particularly chips). It can be effectively prevented. The anionic surfactant (B) may be a sulfonate, carboxylate, sulfate ester salt, phosphate salt or phosphate ester salt.

  Basic substances constituting the salt include inorganic bases [ammonia, alkali metals (sodium, potassium, etc.), alkaline earth metals (calcium, magnesium, etc.)], organic bases [lower alkylamines (trimethylamine, triethylamine, tributylamine). Etc.), alkanolamines (ethanolamine, diethanolamine, dimethylaminoethanol, etc.)] and the like. The salt is often an ammonium salt, an alkali metal salt (sodium salt, potassium salt, etc.), an alkylamine salt or an alkanolamine salt.

Examples of the sulfonate include alkane sulfonate [C _10-20 alkane sulfonate such as lauryl sulfonate (such as sodium C _10-18 alkane sulfonate)], arene sulfonate (benzene sulfonate, naphthalene, etc.). C _6-10 arene sulfonates such as sulfonates), alkyl arene sulfonates [C _4-20 alkyl C _6-10 such as octyl benzene sulfonate, undecyl naphthalene sulfonate, dodecyl benzene sulfonate, etc. Arene sulfonates (such as sodium dodecylbenzenesulfonate)], alkyl sulfosuccinates [di-C _6-20 alkyl sulfosuccinates such as di- (2-ethylhexyl) sulfosuccinate (di- (2-ethylhexyl) sulfosuccinate) Such as sodium acid) ], Such as α- olefin sulfonate can be exemplified.

Examples of the carboxylate include saturated carboxylates (C ₈ such as octylate, caprate, laurate, myristate, palmitate, stearate, isostearate, arachidate, and behenate. _-26 saturated fatty acid salts, etc.), unsaturated carboxylates (myristoleate, palmitoleate, petrothelate, oleate, linoleate, linolenate, ricinoleate, elaidate, gatrenate And C _8-26 unsaturated fatty acid salts such as arachidonate, erucate, and brassinate).

As the sulfate ester salt, alkyl sulfate ester salt or alkenyl sulfate ester salt (higher alcohol sulfate ester salt) [lauryl sulfate ester salt (such as sodium lauryl sulfate ester), C _10-20 alkyl sulfate ester salt such as octadecyl sulfate ester salt, oleyl C _10-20 alkenyl sulfates, such as sulfuric acid ester salts (such as sodium oleyl sulfate), alkyl ether sulfate ester salt (lauryl ether sulfate, polyoxyethylene · C _10-20 alkyl ether sulfate, etc. And the like.

Examples of phosphates or phosphate esters include mono- or dialkyl phosphates [octyl phosphate esters (such as sodium octyl phosphate), C _8-20 alkyl phosphate esters such as dodecyl phosphate, etc.] Examples thereof include mono- or dialkyl phosphates such as polyoxyethylene / alkyl phosphate esters (polyoxyethylene / alkyl phosphate sodium, etc.) and polyoxyethylene / alkyl aryl phosphates.

These anionic surfactants (B) can be used alone or in combination of two or more. Among these anionic surfactants (B), alkane sulfonate, carboxylate, alkyl sulfate ester salt, especially C _10-20 alkane sulfonate (such as C _10-18 sodium alkane sulfonate), saturated or Unsaturated _C10-24 carboxylates (such as _C10-20 unsaturated carboxylates such as potassium oleate) are preferred.

  The anionic surfactant (B) is also preferably a solid at room temperature (20 to 25 ° C.) from the viewpoint that the antifogging property can be improved and the transfer to the roll and the adhesion and set-off can be suppressed. The melting point or softening point of the anionic surfactant (B) is 50 ° C. or higher (eg, about 50 to 300 ° C.), preferably 60 ° C. or higher (eg 60 to 280 ° C.), more preferably 80 ° C. or higher (eg 80 to 80 ° C.). About 250 ° C.).

  The weight ratio of the nonionic surfactant (A) and the anionic surfactant (B) can be selected from the range of the former / the latter = 99/1 to 30/70, for example, 95/5 to 40/60. (For example, 95/5 to 45/55), preferably 90/10 to 50/50 (for example, 90/10 to 60/40), more preferably 90/10 to 65/35 (particularly 90/10 to 70/30) ) If the proportion of the anionic surfactant is too small, the effect of preventing the adhesion of fine particles is lowered, and if it is too much, the antifogging property may be lowered.

(C) Hydrophilic polymer The antifogging layer suppresses a decrease in antifogging property due to secondary processing such as container molding, and suppresses a decrease in antifogging property due to the antifogging layer transfer accompanying sheet winding. Furthermore, a hydrophilic polymer (C) may be included. As the hydrophilic polymer (C), various polymers having a function as a binder can be used. The hydrophilic polymer (C1) containing no oxyalkylene unit (oxyethylene unit, etc.) and a polyoxyalkylene polymer ( C2).

  The hydrophilic polymer (C1) not containing an oxyalkylene unit includes a polymer having a carboxyl group such as poly (meth) acrylic acid or a salt thereof, a polymer having a sulfonic acid group such as ethylene sulfonic acid or a salt thereof, Hydroxyl group-containing polymers such as polyethylene glycol mono (meth) acrylate, vinyl alcohol polymers such as polyvinyl alcohol, amide group-containing polymers such as poly (meth) acrylamide, basic nitrogen atom-containing polymers such as polyvinylpyrrolidone, Examples include vinyl ether polymers, cellulose derivatives, water-soluble polyesters, and natural polymer polysaccharides. These hydrophilic polymers (C1) can be used alone or in combination of two or more.

  Of these hydrophilic polymers (C1), vinyl pyrrolidone polymers, vinyl alcohol polymers, cellulose ethers, alginic acid or salts thereof are preferred.

  The vinyl pyrrolidone-based polymer includes vinyl pyrrolidone or a derivative thereof alone or as a copolymer, for example, polyvinyl pyrrolidone, a copolymer of vinyl pyrrolidone and a copolymerizable monomer [for example, the (meth) acrylic monomer And a copolymer with a copolymerizable monomer such as vinyl acetate, vinyl imidazole and vinyl caprolactam (for example, vinyl pyrrolidone-vinyl acetate copolymer). The vinyl pyrrolidone polymers can be used alone or in combination of two or more. The proportion of vinylpyrrolidone or a derivative unit thereof in the vinylpyrrolidone polymer may be, for example, 30 to 100% by weight, preferably 50 to 95% by weight, and more preferably about 60 to 90% by weight. When the ratio of vinylpyrrolidone or a derivative thereof is 30% by weight or more, it is advantageous in terms of antifogging property.

The glass transition temperature (Tg) of the vinylpyrrolidone polymer is, for example, about 55 to 250 ° C., preferably 60 to 240 ° C. (eg 63 to 230 ° C.), and more preferably 65 to 220 ° C. (eg 68 to 200 ° C.). It may be. The molecular weight of the vinylpyrrolidone polymer is not particularly limited. For example, the weight average molecular weight is 1 × 10 ^{4 to} 500 × 10 ⁴ , preferably 5 × 10 ^{4 to} 300 × 10 ⁴ , and more preferably 10 × 10 ^4. It may be about ˜250 × 10 ⁴ .

  Examples of vinyl alcohol polymers include saponified products of fatty acid vinyl ester polymers (single or copolymer) such as polyvinyl alcohol (fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol), partially acetalized polyvinyl alcohol, and ethylene. -Vinyl alcohol copolymer, vinyl alcohol-ethylene sulfonic acid copolymer, vinyl alcohol-maleic acid copolymer, etc. are mentioned. These vinyl alcohol polymers can be used alone or in combination of two or more. Of these, polyvinyl alcohol is preferred.

  The saponification degree of the vinyl alcohol polymer is not particularly limited, but is, for example, 60 to 100 mol%, preferably 70 to 100 mol% (for example, 80 to 99 mol%), more preferably about 85 to 100 mol%. It may be. The melting point or softening point of the vinyl alcohol polymer may be about 130 to 250 ° C, preferably 150 to 240 ° C, and more preferably about 170 to 230 ° C (for example, 180 to 220 ° C). The degree of polymerization (or average degree of polymerization) of the vinyl alcohol polymer may be, for example, 100 or more (for example, 100 to 5000), preferably 200 to 4000, and more preferably about 500 to 3000.

Cellulose ethers include C _1-4 alkyl cellulose such as methyl cellulose, hydroxy C _2-4 alkyl cellulose such as hydroxyethyl cellulose and hydroxypropyl cellulose, hydroxy C _2-4 alkyl-C ₁ such as hydroxyethyl methyl cellulose and hydroxypropyl methyl cellulose. _And carboxy C _1-4 alkyl cellulose such as _-4 alkyl cellulose and carboxymethyl cellulose. These cellulose ethers can be used alone or in combination of two or more.

  Alginic acid is a linear polymer polysaccharide obtained by extraction from brown algae plants such as kombu, wakame and kajime, and is a heteropolymer containing D-mannuronic acid and L-guluronic acid as constituent units. . Examples of the salt of alginic acid include a salt of alginic acid and an inorganic base. Specifically, ammonium salt; alkali metal salt such as potassium salt and sodium salt; alkaline earth metal salt such as calcium salt and magnesium salt; silver Examples thereof include transition metal salts such as salts and copper salts. Of these salts, monovalent metal salts (such as alkali metal salts) are preferable in addition to ammonium salts. These alginic acids or salts thereof can be used alone or in combination of two or more.

Examples of the polyoxyalkylene polymer (C2) include polyoxyethylene (or polyethylene glycol), polyoxyethylene-polyoxypropylene copolymer [for example, polyoxyethylene-polyoxypropylene block copolymer (hereinafter simply referred to as POE-). Examples thereof include polymers having oxy C _2-4 alkylene units (particularly oxyethylene units). These polyoxyalkylene polymers (C2) can be used alone or in combination of two or more. Of these, POE-POP block copolymers are preferred.

  The content of the ethylene oxide chain in the POE-POP block copolymer is 10 to 99% by weight, preferably 15 to 95% by weight, more preferably 20 to 95% by weight, particularly about 30 to 90% by weight. Also good. The block structure of the block copolymer is not particularly limited, and may be a diblock structure or a triblock structure in which oxyethylene blocks are bonded to both ends of an oxypropylene block.

The POE-POP block copolymer is a copolymer composed of an oxyethylene block — (CH ₂ CH ₂ O) _m — and an oxypropylene block — (CH (CH ₃ ) CH ₂ O) _n —, The ethylene oxide chain content (m / (m + n) × 100) in the copolymer is 10 to 99% by weight, preferably 15 to 95% by weight, more preferably 20 to 95% by weight, especially 30 to 90% by weight. % May be sufficient. The block structure of the block copolymer is not particularly limited, and may be a diblock structure of an oxyethylene block and an oxypropylene block, a triblock structure in which oxyethylene blocks are bonded to both ends of the oxypropylene block, or the like. A copolymer having a triblock structure can be represented by the following formula.

_{HO- (CH 2 CH 2 O)} m1 - (CH (CH 3) CH 2 O) n - (CH 2 CH 2 O) m2 -H

  The content [(m1 + m2) / (m1 + m2 + n) × 100] of the ethylene oxide chain in the triblock copolymer is the same as the content (m / (m + n) × 100) of the ethylene oxide chain in the copolymer. You can select from a range.

  The POE-POP block copolymer may be used alone, or two or more copolymers having different ethylene oxide chain content, block structure, molecular weight, and the like may be used in combination.

  The melting point or softening point of the polyoxyalkylene polymer (C2) is usually less than 60 ° C. (for example, 45 to 59 ° C.), preferably 48 to 59 ° C., more preferably about 50 to 58 ° C. The weight average molecular weight of the polyoxyalkylene polymer (C2) is not particularly limited, and is 1,000 to 1,000,000, preferably 3,000 to 500,000, more preferably 5,000 to 400,000 ( In particular, it may be about 10,000 to 300,000).

  The ratio of the hydrophilic polymer (C) is, for example, 1 to 80 parts by weight, preferably 5 to 60 parts per 100 parts by weight in total of the nonionic surfactant (A) and the anionic surfactant (B). It is about 15 parts by weight (for example, 10 to 30 parts by weight), more preferably about 15 to 40 parts by weight (particularly 20 to 30 parts by weight). If the ratio of the hydrophilic polymer (C) is too large, the antifogging property may be lowered.

  When combining the hydrophilic polymer (C1) and the polyoxyalkylene polymer (C2), the weight ratio of the two is the former / the latter = 99/1 to 50/50, preferably 95/5 to 60/40, Preferably it is about 90 / 10-65 / 35. By combining both, the durability of the antifogging layer can be improved.

(D) Release agent The antifogging layer may further contain a release agent (or an antiblocking agent) in order to improve the release property. Examples of the release agent include various conventional release agents such as waxes (including mineral waxes, plant waxes, synthetic waxes, etc.), silicone compounds, and the like. Of these, silicone oil is preferred.

  Examples of the silicone oil include (halo) alkyl polysiloxanes such as dimethylpolysiloxane, diethylpolysiloxane, and trifluoropropylpolysiloxane; arylpolysiloxanes such as diphenylpolysiloxane; alkylarylpolysiloxanes such as methylphenylpolysiloxane. Can be mentioned. The silicone oil may be a chain polysiloxane or a cyclic polysiloxane.

Furthermore, the silicone oil is a modified silicone oil such as a hydroxyalkyl group (such as a hydroxy _C2-4 alkyl group such as a hydroxyethyl group), a polyoxyalkylene group, an amino group, an N-alkylamino group, a glycidyl group or an epoxy group. Or a silicone oil having a polymerizable group (such as a vinyl group or a (meth) acryloyl group).

  These silicone oils can be used alone or in combination of two or more. Of these silicone oils, dimethylpolysiloxane having high versatility is usually used. Silicone oil can be used in various forms, but is usually used in the form of a silicone emulsion (emulsion in which silicone oil is emulsified and dispersed).

The viscosity of the silicone oil is not particularly limited. For example, the Ostwald viscosity at room temperature (15 to 25 ° C.) is 50 to 50000 cSt (centistokes) (0.5 × 10 ^{−4 to} 500 × 10 ⁻⁴ m ² / s). , Preferably about 100 to 30000 cSt (1 × 10 ^{−4 to} 300 × 10 ⁻⁴ m ² / s), more preferably about 150 to 25000 cSt (1.5 × 10 ⁻⁴ to 250 × 10 ⁻⁴ m ² / s) It may be.

  The ratio of the release agent (D) is, for example, 0.1 to 100 parts by weight with respect to a total of 100 parts by weight of the nonionic surfactant (A), the anionic surfactant (B), and the hydrophilic polymer (C). The amount is about 50 parts by weight, preferably about 1 to 30 parts by weight, and more preferably about 3 to 25 parts by weight (particularly 5 to 20 parts by weight). When the ratio of the release agent is too small, the effect of improving the mold release property is reduced, and when it is too large, the antifogging property may be lowered.

(E) Metal ions The antifogging layer may further contain metal ions (E). In this invention, by mix | blending a metal ion with an anti-fogging layer, while the applicability | paintability of an anti-fogging layer can be improved and a uniform surface can be formed, surface resistivity can also be reduced and adhesion of microparticles | fine-particles can be suppressed. Furthermore, even if the obtained antifogging sheet is subjected to secondary processing (such as container molding by thermoforming), it is possible to suppress a decrease in the uniformity of the antifogging layer and maintain antifogging properties before the secondary processing.

  The metal ion (E) may be a monovalent or polyvalent metal ion. Examples of monovalent metal ions include alkali metal ions such as lithium ions, sodium ions, and potassium ions; Group 11 metal ions such as silver ions and copper (I) ions. Examples of the polyvalent metal ions include divalent metal ions [for example, alkaline earth metal ions such as magnesium ion, calcium ion, strontium ion and barium ion; Group 7 metal ion such as manganese (II) ion; iron Group II metal ions such as (II) ions; Group 9 metal ions such as cobalt (II) ions; Group 10 metal ions such as nickel (II) ions; Group 11 metal ions such as copper (II) ions; 12 group metal ions such as cadmium ion and mercury (II) ion; 14 group metal ions such as tin (II) ion and lead (II) ion], trivalent metal ion [for example, chromium (III) ion, etc. Group 6 metal ion; Group 8 metal ion such as iron (III) ion; Group 13 metal ion such as aluminum ion], tetravalent metal ion [for example , Group 7 metal ions such as manganese (IV) ion; Group 14 metal ions such as tin (IV) ion] and the like. These metal ions can be used alone or in combination of two or more.

  Among these metal ions, monovalent metal ions such as alkali metal ions, divalent metal ions such as alkaline earth metal ions, etc. are widely used. From the viewpoint of suppressing the decrease in uniformity of the antifogging layer due to processing, polyvalent metal ions (especially divalent metal ions) are preferable, and alkaline earth metal ions such as magnesium ions and calcium ions are particularly preferable.

  Among these, there are many alkali metal salts in anionic surfactants, and in the conventional technical common sense, adding a polyvalent metal ion decreases the surface activity, so that it was not assumed to be added. On the other hand, in the present invention, it has been found that the application property of the anionic surfactant is improved by the combination with the polyvalent metal ion, and thus the technical significance of the present invention is particularly great.

  The metal ion (E) can usually be used in the form of a halide (especially chloride) or an inorganic salt (especially an inorganic acid salt such as sulfuric acid or nitric acid), for example, a metal chloride such as magnesium chloride or calcium chloride, It can be used in the form of inorganic acid salts such as magnesium sulfate and magnesium nitrate. Among these, from the point that corrosiveness to metals does not become a problem, a form containing no chlorine, for example, an inorganic acid salt such as magnesium sulfate or magnesium nitrate is preferable. In addition, sulfates such as magnesium sulfate are preferable from the viewpoint of improving the wettability of the coating solution and highly improving the coating property. On the other hand, metal chlorides such as magnesium chloride are preferred from the viewpoint that the surface resistivity of the antifogging layer can be reduced with a small amount.

  The ratio of the metal ion (E) is, for example, a total of 1 g of the nonionic surfactant (A), the anionic surfactant (B), the hydrophilic polymer (C) and the release agent (D). It can select from the range of about 0.01-50 mmol, Preferably it is 0.02-30 mmol, More preferably, it is about 0.03-20 mmol (especially 0.04-10 mmol). In particular, the ratio of metal ions (E) is, for example, 0.08 to 50 mmol (for example, 0.1 to 50 mmol) with respect to the total of 1 g from the point that a uniform surface can be easily formed regardless of the type of coating method. ), Preferably 0.09 to 30 mmol (for example, 0.2 to 30 mmol), more preferably about 0.1 to 20 mmol (for example, 0.3 to 20 mmol), particularly about 0.11 to 10 mmol (for example, 0.5 to 10 mmol). From the balance of various properties, it may be, for example, about 0.2 to 5 mmol, preferably 0.3 to 3 mmol, more preferably about 0.4 to 2 mmol (especially 0.5 to 1 mmol). is there. Furthermore, in applications where antistatic properties are required, the ratio of the metal ions (E) is, for example, 0.3 to 50 mmol, preferably 0.5 to 30 mmol, more preferably 1 to 20 mmol, with respect to 1 g of the total. In particular, it may be about 2 to 5 mmol).

  The ratio of the metal ion (E) may be about 0.05 to 200 mmol (particularly 0.3 to 200 mmol) with respect to 1 g of the anionic surfactant (B), for example, 0.5 to 50 mmol, preferably It is about 1-10 mmol, More preferably, it is about 1.5-5 mmol (especially 2-3 mmol).

  If the ratio of the metal ions (E) is too small, the effect of improving the coating appearance and antistatic properties is reduced, and if it is too large, the mechanical properties of the antifogging layer may be lowered.

  In applications where corrosion resistance to metals is required, the antifogging layer preferably has a low chlorine ion concentration from the point that the corrosion resistance can be improved, and is based on the entire coating solution for forming the antifogging layer. It may be 100 ppm or less, preferably 50 ppm or less, and particularly preferably 10 ppm or less. Therefore, when using a metal salt containing chlorine (for example, magnesium chloride), the ratio of the metal ion (E) is, for example, 0.01 to 0.2 mmol, preferably 0.02 to 0 with respect to the total 1 g. .18 mmol, more preferably about 0.03 to 0.15 mmol (particularly 0.04 to 0.12 mmol). In addition, when the ratio of the metal ions (E) is within this range, the coating property (surface appearance) for forming a uniform surface is lower than that of the antifogging layer containing the metal ions (E) at a high concentration. However, the applicability can be improved by a method of adjusting the coating method (for example, a method using a roll coater or a spray).

(F) Other additives The anti-fogging layer comprises various conventional additives such as stabilizers (antioxidants, ultraviolet absorbers, etc.), fillers, colorants, antistatic agents, flame retardants, lubricants, antiseptics. Agents, viscosity modifiers, thickeners, leveling agents, antifoaming agents (such as silicone-based antifoaming agents), and the like. The ratio of other additives is not particularly limited, but is about 10% by weight or less (for example, 0.1 to 10% by weight) with respect to the entire antifogging layer.

[Release layer]
A release layer is laminated on the other surface of the base material layer. The release layer has a negative triboelectric potential from the viewpoint of preventing adhesion of fine particles (particularly chips). The triboelectric charging potential of the release layer may be a negative potential, but may be, for example, less than 0 kV (for example, −0.1 to −10 kV), preferably −0.3 to −8 kV, more preferably − It may be about 0.3 to -6 kV.

The release layer may have a surface resistivity of 8 × 10 ¹³ Ω or less, for example, 1 × 10 ^{7 to} 5 × 10 ¹³ Ω, preferably 1 × from the viewpoint of preventing adhesion of fine particles (particularly dust). It is about 10 ^{8 to} 3 × 10 ¹³ Ω, more preferably about 1 × 10 ⁹ to 2 × 10 ¹³ Ω (particularly 1 × 10 ⁹ to 1 × 10 ¹³ Ω).

(A) Release agent The release layer contains a release agent (a). As the release agent, the same release agent as the release agent (D) of the antifogging layer can be used, and the preferred release agent in the release agent (a) is the same as that of the release agent (D). .

  The ratio of the release agent (a) may be about 10% by weight or more with respect to the whole release layer, for example, 30 to 97% by weight, preferably 50 to 95% by weight, more preferably 60 to 92% by weight. (Especially 70 to 90% by weight). If the ratio of the release agent is too small, the release property may be lowered.

(B) Anionic surfactant The release layer further contains an anionic surfactant (b). In the present invention, the friction charge potential can be adjusted to a negative potential by combining the anionic surfactant (b) with the release agent (a), or the adhesion of fine particles (particularly chips) is effectively prevented. it can.

  As the anionic surfactant (b), an anionic surfactant similar to the anionic surfactant (B) of the antifogging layer can be used, and preferred anionic surfactant in the anionic surfactant (b) The agent is the same as the anionic surfactant (B).

  The weight ratio of the release agent (a) and the anionic surfactant (b) can be selected from the range of the former / the latter = about 99.9 / 0.1 to 30/70, for example, 99/1 to 40 / 60 (for example 97/3 to 50/50), preferably 96/4 to 60/40 (for example 95/5 to 65/35), more preferably 90/10 to 70/30 (particularly 90/10 to 75 / 25) About. If the proportion of the anionic surfactant is too small, the effect of preventing the adhesion of fine particles is lowered, and if it is too much, the releasability may be lowered.

(C) Metal Ion The release layer may further contain a metal ion (c) from the viewpoint that a uniform surface appearance can be formed and adhesion of fine particles can be suppressed. As the metal ion (c), the same metal ion as the metal ion (E) of the antifogging layer can be used, and the preferred metal ion in the metal ion (c) is also a metal ion ( Same as E).

  The ratio of the metal ion (c) can be selected from the range of, for example, about 0.01 to 50 mmol, preferably 0.02 to 1 g in total of the release agent (a) and the anionic surfactant (b). It is about 30 mmol, more preferably about 0.025 to 20 mmol (particularly 0.03 to 10 mmol). In particular, the ratio of the metal ions (c) is, for example, 0.08 to 50 mmol (for example, 0.1 to 50 mmol) with respect to the total of 1 g because a uniform surface can be easily formed regardless of the type of coating method. ), Preferably 0.09 to 30 mmol (for example, 0.2 to 30 mmol), more preferably about 0.1 to 20 mmol (for example, 0.3 to 20 mmol), particularly about 0.11 to 10 mmol (for example, 0.5 to 10 mmol). From the balance of various properties, it may be, for example, about 0.2 to 5 mmol, preferably 0.3 to 3 mmol, more preferably about 0.4 to 2 mmol (especially 0.5 to 1 mmol). is there. Furthermore, in applications where antistatic properties are required, the ratio of the metal ion (c) is, for example, 0.3 to 50 mmol, preferably 0.5 to 30 mmol, more preferably 1 to 20 mmol with respect to 1 g of the total. In particular, it may be about 2 to 5 mmol).

  The ratio of the metal ion (c) may be about 0.05 to 200 mmol (particularly 0.3 to 200 mmol), for example 0.5 to 50 mmol, preferably 1 to 1 g of the anionic surfactant (b). It is about 1-10 mmol, More preferably, it is about 1.5-5 mmol (especially 2-3 mmol).

  If the proportion of the metal ion (c) is too small, the effect of improving the coating appearance and antistatic properties is reduced, and if it is too large, the mechanical properties of the release layer may be reduced.

  The release layer also preferably has a low chloride ion concentration from the viewpoint of improving the corrosion resistance against metals, and may be 100 ppm or less, and 50 ppm or less with respect to the entire coating solution for forming the release layer. Preferably, 10 ppm or less is particularly preferable. Therefore, when using a metal salt containing chlorine (for example, magnesium chloride), the ratio of the metal ion (c) is, for example, 0.01 to 0.2 mmol, preferably 0.02 to 0, relative to the total 1 g. .18 mmol, more preferably about 0.03 to 0.15 mmol (particularly 0.04 to 0.12 mmol). In addition, when the ratio of the metal ions (c) is within this range, the coating property for forming a uniform surface is lowered as compared with the release layer containing the metal ions (c) at a high concentration. The surface appearance can be improved by a method of adjusting (for example, a method using a roll coater).

(D) Other additives The release layer may contain the same nonionic surfactant and / or hydrophilic polymer as the antifogging layer.

  As the nonionic surfactant, a nonionic surfactant similar to the nonionic surfactant (A) of the antifogging layer can be used, and a preferable nonionic surfactant is also a nonionic surfactant. It is the same as agent (A). The weight ratio between the release agent (a) and the nonionic surfactant can be selected from the range of the former / the latter = 99.99 / 0.01 to 50/50, for example, 99.9 / 0.1 70/30, preferably about 99/1 to 80/20.

  As the hydrophilic polymer, the same hydrophilic polymer as the hydrophilic polymer (C) of the antifogging layer can be used, and the preferred hydrophilic polymer is the same as the hydrophilic polymer (C). The weight ratio between the release agent (a) and the hydrophilic polymer can be selected from the range of the former / the latter = 99.99 / 0.01 to 50/50, for example, 99.9 / 0.1 to 70 / 30 or preferably about 99/1 to 80/20.

  The release layer may also contain the same conventional additives as the antifogging layer. The ratio of other additives is not particularly limited, but is about 10% by weight or less (for example, 0.1 to 10% by weight) with respect to the entire release layer.

[Method for producing anti-fogging sheet]
The antifogging sheet can be produced by applying a composition for forming an antifogging layer on one surface of the base material layer and further applying a composition for forming a release layer on the other surface.

  The composition for forming the antifogging layer and the release layer can be usually used in the form of a coating solution (dope) or impregnating solution, and may be a non-aqueous liquid composition using an organic solvent as a solvent, Usually used as an aqueous composition. In the aqueous composition, the solvent may be water alone, water and a hydrophilic solvent (especially a water miscible solvent) [for example, alcohols (methanol, ethanol, isopropanol, etc.), ketones (acetone, etc.), A mixed solvent with ethers (dioxane, tetrahydrofuran, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, butyl cellosolve, etc.), carbitols, etc.] may be used. When water is used, it may be pure water (or ion exchange water) or drinking water.

  The solid content concentration of the coating solution can be selected from a range of, for example, about 0.1 to 10% by weight, for example, 0.1 to 7% by weight, preferably 0.3 to 5% by weight, and more preferably 0.5 to 3%. It is about wt%. The viscosity of the coating solution is, for example, 10 cps (= 0.01 Pa · s) or less, preferably 1.1 to 5 cps (for example 1.2 to 3 cps) at a temperature of 20 ° C., as measured by a steady flow viscosity measurement method. More preferably, it may be about 1.3 to 2 cps.

  The coating liquid can be prepared by mixing the above components using a conventional mixing stirrer or mixing / dispersing machine. However, the anionic surfactant is diluted in advance with a solvent from the viewpoint of improving the coating properties of the coating liquid. It is preferable to prepare by a method including a pre-dilution step, a main mixing step of mixing the diluent obtained in the pre-dilution step and other additives in the presence of a solvent. In the preliminary dilution step, as the solvent, a solvent constituting the antifogging surface treatment agent (in particular, water or a mixed solvent of water and a hydrophilic solvent) can be used. The water may be pure water (or ion exchange water) or drinking water. You may add this solvent so that the density | concentration of anionic surfactant may be about 1-50 weight%, for example, Preferably it is 2-40 weight%, More preferably, it is about 5-35 weight%. The stirring speed is, for example, about 400 to 1200 rpm, preferably about 500 to 1000 rpm, and more preferably about 600 to 900 rpm. The stirring time is, for example, about 10 minutes to 10 hours, preferably about 20 minutes to 5 hours, more preferably about 30 minutes to 3 hours (particularly about 45 minutes to 2 hours).

  When metal ions are included, the metal ions can be added in the preliminary dilution step or the main mixing step. As the solvent, a solvent constituting the antifogging surface treatment agent (particularly water or a mixed solvent of water and a hydrophilic solvent) can be used. The water may be pure water (or ion exchange water) or drinking water. The metal ion may be used as a solid metal salt or in the form of an aqueous solution. The concentration of the aqueous solution may be added so that the metal ions are about 0.01 to 10% by weight, preferably about 0.05 to 5% by weight.

  For application of the coating solution, conventional application means such as spray, roll coater, gravure roll coater, bar coater, knife coater, dip coater and the like can be used. Of these, roll coaters and bar coaters are widely used. If necessary, the coating solution may be applied multiple times. After the coating liquid is applied to the base material layer, the coating layer is usually dried, and then spread on a roll (for example, a metal roll such as a guide roll) and wound on a winding roll. Since the anti-fogging sheet of the present invention can be wound without contaminating the roll, the anti-fogging component can be largely prevented from transferring (set-off) even in the core sheet, and the anti-fogging sheet is highly antifogged over a long period of time. Can maintain sex. Moreover, whitening can be suppressed and the transparency and gloss of the resin sheet are not impaired. Therefore, it can be used for various uses, for example, a cover sheet (or film), a packaging sheet (or film) such as food packaging.

The coating amount of the antifogging layer (the coating amount after drying) can be selected from a wide range of, for example, about ^{2 to} 150 mg / m ² (for example, 3 to 100 mg / m ² ), and is usually 5 to 60 mg / m ² (for example, 7). ˜50 mg / m ² ), preferably about 10 to 40 mg / m ² .

The coating amount of the release layer (coating amount after drying) can be selected from a wide range of about 1 to 200 mg / m ² (for example, 5 to 100 mg / m ² ), and is usually ^{2 to} 100 mg / m ² , preferably 3-50 mg / m < ² > (for example, 5-30 mg / m < ² >), More preferably, about 5-25 mg / m < ² > may be sufficient.

  The antifogging sheet may be continuously provided in a post-treatment process (such as a container molding process), but is usually wound in a roll and is often provided in a post-treatment process. The anti-fogging sheet of the present invention has high secondary processability and is suitable for molding processing of containers and the like.

[container]
The container (anti-fogging container) of the present invention is formed of the anti-fogging sheet, and is excellent in anti-fogging and transparency, so that it contains a container containing water such as a food packaging container. It is useful as such.

  The container of the present invention usually has at least a container main body for storing a container such as food, and the opening of the container main body may be covered with a wrapping film. Moreover, you may comprise the container of this invention with a container main body and the cover body which covers the opening part of the said container main body via a hinge part. In the molded product having a lid, the lid may also be formed of the antifogging sheet of the present invention.

  In many cases, the container of the present invention is formed from the antifogging sheet by a conventional thermoforming method. Examples of thermoforming methods include blow molding, vacuum forming, pressure forming (heating plate heating type pressure forming method, radiation heating type pressure forming method, etc.), vacuum pressure forming method, plug assist forming. Method and matched mold forming method can be used. When using a stretched resin sheet, a hot plate heating type pressure forming method is usually used in many cases.

  In the present invention, high antifogging properties and transparency can be maintained even when subjected to such thermoforming. Furthermore, since the anti-fogging sheet of the present invention can prevent adhesion of fine particles, it may be a sheet obtained by a method including punching in the manufacturing process. For example, after a container (tray part) for food or the like is continuously molded in the vertical and / or horizontal direction, a container having each container is obtained by continuously punching the obtained molded sheet. It can be suitably used for a method of separating (cutting). In the punching process, a plurality of sheets may be laminated and used for the punching process. In such a method, chips are easily generated, and thus the antifogging sheet of the present invention is useful.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, the detail of the component used by the Example and the comparative example is as follows, The antifogging sheet | seat obtained by the Example and the comparative example was evaluated by the following items.

[Ingredients used]
A-1 (nonionic surfactant 1): sucrose fatty acid ester, “Rikemar A” manufactured by Riken Vitamin Co., Ltd., melting point 90 ° C., solid content concentration 40% by weight
B-1 and b-1 (anionic surfactant 1): sodium alkanesulfonate, “KTN-8006” manufactured by Sanyo Chemical Industries, Ltd., solid content concentration 35% by weight
B-2 and b-2 (anionic surfactant 2): potassium oleate, “FR-14” manufactured by Kao Corporation, solid content concentration 20% by weight
C-1 (hydrophilic polymer 1): polyoxyethylene-polyoxypropylene block copolymer, “Epan U108” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., melting point 57 ° C., weight average molecular weight 18000, ethylene oxide content 80%
C-2 (hydrophilic polymer 2): polyvinylpyrrolidone, “Socaran K90P” manufactured by BASF, glass transition temperature 180 ° C., weight average molecular weight 90 × 10 ^{4 to} 150 × 10 ⁴
C-3 (hydrophilic polymer 3): polyvinyl alcohol, “PVA-505” manufactured by Kuraray Co., Ltd., saponification degree: 72.5 to 74.5 mol%
D-1 and a-1 (silicone emulsion): “SM7025EX” manufactured by Toray Dow Corning Co., Ltd., solid content concentration: 33% by weight
E-1 and c-1: Magnesium chloride hexahydrate (Mg ²⁺ ) manufactured by Nacalai Tesque Co. E-2 and c-2: Magnesium sulfate heptahydrate (Mg ²⁺ ) manufactured by Nacalai Tesque Co., Ltd. .

[Frictional charging potential]
In accordance with JIS C61340-2-2, the coated sheet is cut to 5 cm × 10 cm, and the sheet is moved back and forth on the 20 cm × 20 cm square carbon steel (S55C) plate by 20 reciprocations at a rate of 20 cm / second for friction. Then, the charging potential of the friction surface of the sheet was measured with a charging potential measuring machine (“KSD-0103” manufactured by Kasuga Denki Co., Ltd.) under the conditions of a temperature of 23 ° C. and a humidity of 50% RH.

[Surface resistivity]
In accordance with JIS K6911, the coated sheet was cut into 5 cm × 10 cm, and was measured with a resistance meter (“Hiresta-up MCP-HT450” manufactured by Mitsubishi Chemical Corporation) at a temperature of 23 ° C. and a humidity of 50% RH. The surface resistivity when a voltage was applied was measured.

[Anti-fogging property (sheet)]
The sheet was placed with the antifogging layer of the antifogging sheet facing the opening of a container containing hot water at 60 ° C., and left in a room temperature environment for 2 minutes. Next, the steam contact portion of the sheet was placed on characters with different font sizes printed on paper, and the degree of fogging of the sheet was visually evaluated according to the following criteria.

○: Characters with a font size of 5 can be read clearly. Δ: Characters with a font size of 18 can be read. ×: Characters cannot be identified.

[Anti-fogging property (secondary processed product)]
A container obtained by secondary processing of an antifogging sheet (stretching ratio: 1.6 times, stretching ratio = sheet thickness / sheet thickness after secondary processing) in an opening of a container containing hot water at 60 ° C. The sheet was placed facing the opening, and allowed to stand in a room temperature environment for 2 minutes. Next, the steam contact portion of the secondary processed product was placed on characters with different font sizes printed on paper, and the degree of cloudiness of the sheet was visually evaluated according to the following criteria.

○: Characters with a font size of 5 can be read clearly. Δ: Characters with a font size of 18 can be read. ×: Characters cannot be identified.

[Amount of chips adhering]
Of the molded products in a state where 25 sheets were laminated, the number of molded products to which chips adhered was visually observed and evaluated according to the following criteria.

○: There is no molded product with chips attached. Δ: One to two molded products with chips attached. ×: Three or more molded products with chips attached.

[Appearance appearance (application spots)]
The covering sheet was placed on the black pressure-sensitive adhesive sheet so that the observation surface was on top, and the appearance of the antifogging layer or the release layer of the covering sheet was visually observed and evaluated according to the following criteria.

3: There is no coating spot 2: When the eyes are closed, the coating spot can be recognized by the degree of light contact 1: The coating spot is conspicuous.

[Appearance (white dots)]
The appearance of the coating layer of the coating sheet was visually observed and evaluated according to the following criteria.

3: No white spots 2: Fine white spots can be recognized 1: White spots stand out at a level that cannot be used practically.

[Metal corrosivity]
The chlorine ion concentration in the coating solution was evaluated according to the following criteria.

○: 50 ppm or less ×: Over 50 ppm.

[Contact angle]
Using an automatic contact angle meter (“Model CA-Z” manufactured by Kyowa Interface Science Co., Ltd.), the contact angles of the antifogging layer coating solution and the release layer coating solution were measured. Specifically, for the contact angle of the antifogging layer coating solution, about 1.5 μL of the antifogging layer coating solution is applied to the corona discharge treated surface (54 dyn / cm) of the uncoated biaxially stretched polystyrene sheet. Ten contact angles one second after the landing were measured and averaged. On the other hand, with respect to the contact angle of the release layer coating solution, about 1.5 μL of the release layer coating solution was applied to the untreated surface of the uncoated biaxially stretched polystyrene sheet on the corona discharge after 1 second. The subsequent contact angles were measured at 10 points and averaged.

Examples 1 to 13, Comparative Examples 1 to 2 and Reference Example (Preparation of coating solution)
Water (ion-exchanged water) is added to each component and mixed with stirring so that the solid content ratio of each component (weight ratio after drying of each component) is the ratio (parts by weight) shown in Table 1, and the solid content concentration A coating solution (antifogging layer coating solution) for forming a 0.6 wt% antifogging layer and a release layer coating solution having a solid content concentration of 0.3 wt% were prepared.

(Manufacture of coated sheets)
One surface of a biaxially stretched polystyrene sheet having a sheet thickness of 0.25 mm is subjected to corona discharge treatment at 54 dyn / cm or more, and a coating solution for an antifogging layer is applied to the corona discharge treatment surface at a coating amount of 20 mg / m ² after drying. No. An anti-fogging layer was formed by applying with a 5 Mayer bar and drying with a hot air dryer at 80 ° C. for 2 minutes. Further, the other surface of the biaxially stretched polystyrene sheet was not subjected to corona discharge treatment, and the release layer coating solution was applied at a coating amount of 18 mg / m ² after drying. A release layer was formed by applying with a 5 Mayer bar and drying with a hot air dryer at 80 ° C. for 2 minutes. Table 1 shows the results of evaluating the triboelectric potential, surface resistivity, and antifogging property of the obtained coated sheet.

(Manufacture of molded products)
A transparent lid (vertical 185 mm x width 153 mm x height 17 mm) used as a lid for general food containers is heated at about 140 ° C for about 1 second using a hot plate type pneumatic molding machine. The molded product was molded underneath and continuously punched with an automatic punching machine to obtain a molded product in which 25 sheets were laminated. Table 1 also shows the results of evaluating chip adhesion of the obtained molded product.

  As is clear from the results in Table 1, the coated sheets and molded articles obtained in the examples have a negative triboelectric potential and a low surface resistivity. Furthermore, the antifogging property is excellent, and chips do not adhere.

Examples 14-19
Other than adding magnesium chloride to each of the antifogging layer coating solution and the release layer coating solution so that the ratio of magnesium ions (Mg ²⁺ ) is as shown in Table 2 with respect to 1 g of solid content. Table 2 shows the results of preparing a coated sheet in the same manner as in Example 1 and evaluating the triboelectric potential, surface resistivity, antifogging property, coating appearance, metal corrosivity, contact angle and chip adhesion. For magnesium chloride, a magnesium chloride aqueous solution previously diluted to 0.1% by weight was prepared and added to the antifogging layer coating solution and the release layer coating solution. Moreover, the unit of a composition in Table 2 is a weight part except a metal salt (Mg ^<2+> ), and a metal salt is the mmol number of the metal ion with respect to 1g of solid content. Further, Table 2 also shows the results of the same evaluation for Example 1.

  As is clear from the results in Table 2, the antifogging layers and release layers of Examples 14 to 16 had no coating spots, no release layer, no white spots, and low surface resistivity.

  The coating appearances of the antifogging layers and release layers of Examples 17 to 19 were also excellent. In particular, the contact angle of the antifogging layer was low, the wettability with respect to the coating solution was improved, and the coating properties were also excellent. Furthermore, the antifogging layers and the release layers of Examples 17 to 19 were not metal corrosive. In addition, although the anti-fogging layer of Examples 17-19 had the surface specific resistance value high compared with the anti-fogging layer of Examples 14-16, it was a level which is practically satisfactory.

Examples 20 to 26 and Comparative Example 3
(Preparation of coating solution)
Water (ion-exchanged water) is added to each component and mixed with stirring so that the solid content ratio of each component (weight ratio after drying of each component) is the ratio (parts by weight) shown in Table 3, and the solid content concentration A coating solution for forming a 0.64% by weight antifogging layer (antifogging layer coating solution) and a release layer coating solution having a solid concentration of 1.08% by weight were prepared. In addition, the unit of a composition in Table 3 is a weight part except a metal salt (Mg ^<2+> ), and a metal salt is the mmol number of the metal ion with respect to 1g of solid content.

(Manufacture of coated sheets)
One surface of a biaxially stretched polystyrene sheet having a sheet thickness of 0.25 mm is subjected to corona discharge treatment at 54 dyn / cm or more, and a coating solution for an antifogging layer is applied to the corona discharge treatment surface at a coating amount of 20 mg / m ² after drying. The anti-fogging layer was formed by apply | coating with a roll coater and drying for 2 minutes with a 80 degreeC hot air dryer. Further, the other surface of the biaxially stretched polystyrene sheet was not subjected to corona discharge treatment, but was applied with a release layer coating liquid at a coating amount of 18 mg / m ² after drying with a roll coater, and dried with hot air at 80 ° C. A release layer was formed by drying for 2 minutes on a machine. Table 3 shows the results of evaluating the triboelectric potential, surface resistivity, anti-fogging property (sheet and secondary processed product), coating appearance, metal corrosivity and chip adhesion of the obtained coated sheet.

  As is apparent from the results in Table 3, the coated sheets and molded articles obtained in the examples have a negative triboelectric potential and a low surface resistivity. Moreover, both the anti-fogging sheet and its secondary processed product are excellent in anti-fogging properties, and chips do not adhere. Furthermore, the coating appearance is also excellent.

  The anti-fogging sheet of the present invention is useful in various applications where anti-fogging properties are required, for example, various containers (contents), in particular, containers for storing containers containing moisture (such as food). It is.

Claims (17)

A base material layer containing a thermoplastic resin, laminated on one surface of the base material layer and having an anti-fogging layer having a negative triboelectric potential, laminated on the other surface of the base material layer, and negative An antifogging sheet comprising a release layer having a frictional charging potential and a surface resistivity of 2 × 10 ¹³ Ω or less.   The antifogging sheet according to claim 1, wherein the release layer comprises a release agent (a) and an anionic surfactant (b).   The antifogging sheet according to claim 1 or 2, wherein the antifogging layer contains a nonionic surfactant (A) and an anionic surfactant (B).   The anti-fogging sheet according to claim 3, wherein the anti-fogging layer further contains a hydrophilic polymer (C).   The antifogging sheet according to claim 3 or 4, wherein the antifogging layer further contains a release agent (D).   The antifogging sheet according to any one of claims 3 to 5, wherein the antifogging layer further contains a metal ion (E).   The antifogging sheet according to any one of claims 2 to 6, wherein the release layer further contains a metal ion (c).   The anionic surfactant (b) in the release layer and the anionic surfactant (B) in the anti-fogging layer are the same or different, and sulfonate, carboxylate, sulfate, phosphate and phosphoric acid. The antifogging sheet according to any one of claims 3 to 7, which is at least one selected from the group consisting of ester salts.   The antifogging sheet according to any one of claims 2 to 8, wherein a weight ratio of the release agent (a) and the anionic surfactant (b) is 99.9 / 0.1 to 30/70.   The antifogging sheet according to any one of claims 3 to 9, wherein a weight ratio of the nonionic surfactant (A) to the anionic surfactant (B) is 99/1 to 30/70.   The antifogging sheet according to any one of claims 1 to 10, wherein the release layer has a triboelectric charging potential of -0.1 kV or less. The antifogging sheet according to claim 1, wherein the antifogging layer has a surface resistivity of 2 × 10 ¹³ Ω or less.   The antifogging sheet according to any one of claims 1 to 12, wherein the base material layer is a biaxially stretched styrene resin sheet.   A container formed of the antifogging sheet according to claim 1. An antifogging layer having a negative triboelectric charge potential is laminated on one surface of a base material layer containing a thermoplastic resin, and a negative triboelectric charge potential and 2 × 10 ¹³ are formed on the other surface of the base material layer. A method of preventing fine particles from adhering to the surface of an antifogging sheet by laminating a release layer having a surface resistivity of Ω or less.   The method according to claim 15, wherein the fine particles are chips generated by molding an antifogging sheet.   The method according to claim 16, wherein the forming process is a punching process of an antifogging sheet in which tray portions are formed adjacent to each other in the vertical and / or horizontal direction.