Anti-blocking Agent

Abstract

To provide an antiblocker that has reduced particle fallout from a film and can be readily removed with an alkaline solution.SOLUTION: An antiblocker contains polymer particles with alkali-soluble layers. The alkali-soluble layer has a thickness of 10 nm or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an antiblocking agent. [Background technology]

[0002] Resin films have been widely used as various packaging materials. When resin films are stored in a stacked state, the films tend to adhere to each other, so inorganic particles such as silica or particles containing organic resin components are used as antiblocking agents (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-151907 [Patent Document 2] International Publication No. 2017 / 200765 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, inorganic particles and particles containing organic resin components are known to have good antiblocking properties. In recent years, from the viewpoint of environmental protection, there has been a demand for technologies for recycling resin films, and the antiblocking agent contained in the recycled resin film has sometimes become an impurity.

[0005] Therefore, an object of the present invention is to provide an antiblocking agent that has the ability to prevent the agent from falling off from a film and can be easily removed with an alkaline solution. [Means for solving the problem]

[0006] The present inventors have conducted various studies to achieve the above object and have arrived at the present invention. That is, the antiblocking agent of the present disclosure is an antiblocking agent containing polymer particles having an alkali-soluble layer, and the thickness of the alkali-soluble layer is 10 nm or more. [Effects of the Invention]

[0007] According to the present disclosure, an antiblocking agent is provided that causes few particles to fall off from the film and can be easily removed with an alkaline solution. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be described in detail below. Note that a combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

[0009] [Antiblocking Agent of the Present Disclosure] The polymer particles of the present disclosure may be any polymer particles having an alkali-soluble layer that dissolves in an alkaline solution (hereinafter, they may also be referred to as alkali-soluble polymer particles).

[0010] The alkali-soluble layer of the polymer particles of the present disclosure may be present on the surface or inside. Preferably, it is present on the surface, as this tends to make it easier to remove the polymer particles from the film using an alkaline solution.

[0011] The alkali-soluble layer of the polymer particles of the present disclosure may have a multi-layer structure.

[0012] The alkali-soluble layer of the polymer particles of the present disclosure may be partially or completely dissolved.

[0013] An alkaline solution is a solution containing an alkaline compound and a solvent.

[0014] Examples of alkaline compounds include lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, diammonium hydrogen phosphate, dipotassium hydrogen phosphate, disodium hydrogen phosphate, lithium silicate, sodium silicate, potassium silicate, lithium carbonate, sodium carbonate, potassium carbonate, lithium borate, sodium borate, potassium borate, ammonia, trimethylamine, triethylamine, tributylamine, ethanolamine, diethanolamine, and triethanolamine.

[0015] Examples of the solvent include water; alcohols such as methanol, ethanol, isopropyl alcohol, and hexanol; and ketones such as acetone and 2-butanone.

[0016] The alkaline solution is preferably an aqueous alkaline solution. Specific examples include an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous calcium hydroxide solution, and an aqueous ammonia solution. An aqueous sodium hydroxide solution is more preferred.

[0017] The pH of the alkaline solution is preferably 7.5 to 14, more preferably 8.5 to 14, and even more preferably 9.0 to 14.

[0018] The thickness of the alkali-soluble layer of the present disclosure is calculated as the difference (D1-D2) between the volume average particle size (D1) of the alkali-soluble polymer particles of the present disclosure before dissolving (sometimes referred to as treating) them with an alkaline solution and the volume average particle size (D2) of the polymer particles after treating them with an alkaline solution. Here, the volume average particle size of the polymer particles can be measured, for example, by dynamic light scattering.

[0019] The volume average particle diameter (D1) of the polymer particles of the present disclosure is preferably 10 nm or more, more preferably 50 nm or more, and even more preferably 100 nm or more, and is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 2 μm or less.

[0020] The volume average particle diameter (D2) of the polymer particles of the present disclosure after being treated with an alkaline solution is preferably 9.99 μm or less, more preferably 9.9 μm or less, and still more preferably 9.5 μm or less.

[0021] All of the polymer particles of the present disclosure may dissolve in the alkaline solution, and the volume average particle diameter (D2) of the polymer particles after being treated with the alkaline solution may be 0 nm.

[0022] The thickness (D1 - D2) of the alkali-soluble layer of the present disclosure is preferably 10 nm or more, more preferably 20 nm or more, and still more preferably 50 nm or more. On the other hand, it is preferably 10 μm or less, more preferably 5 μm or less, and still more preferably 1 μm or less. Here, when D1 < D2, it is suggested that the alkaline solution is absorbed by the polymer particles.

[0023] Regarding the volume average particle diameter of the present disclosure, the ratio (D2 / D1) before and after alkali solubility is preferably 0 to 1, more preferably 0 to 0.99, and still more preferably 0 to 0.95.

[0024] The time for treating the polymer particles of the present disclosure with an alkaline solution is not limited sometimes, but it is preferably 1 to 720 minutes, more preferably 5 to 120 minutes, and still more preferably 10 to 30 minutes.

[0025] The temperature for treating the polymer particles of the present disclosure with an alkaline solution is not limited sometimes, but it is preferably 10 to 50 °C, more preferably 20 to 40 °C, and still more preferably 20 to 30 °C.

[0026] The temperature at which the alkali-soluble layer of the polymer particles of the present disclosure can dissolve in the alkaline solution is not particularly limited, but it has a high solubility not only at a high temperature such as 90 °C but also at a temperature such as 25 °C.

[0027] <Structural unit represented by general formula (1)> The polymer particles of the present disclosure preferably have structural units derived from an ethylenically unsaturated monomer.

[0028] A structural unit derived from an ethylenically unsaturated monomer refers to a structural unit having the same structure as that formed by polymerization of the monomer, and is usually a structure in which at least one carbon-carbon unsaturated double bond contained in the monomer is replaced with a carbon-carbon single bond. Note that the structural unit derived from the monomer does not necessarily have to be a structural unit formed by actual polymerization of the monomer, and even a structural unit formed by a method other than polymerization of the monomer is included in the structural unit derived from the monomer as long as it has the same structure as that formed by polymerization of the monomer. For example, in the case of acrylic acid, CH═CH(—COOH), the structural unit derived from acrylic acid can be represented by —CH—CH(—COOH)—.

[0029] Examples of functional groups having an affinity for alkaline solutions include hydroxyl groups, carboxylic acid groups, sulfonic acid groups, phosphoric acid groups, groups having salt structures of these groups, epoxy groups, polyoxyethylene groups, and the like.

[0030] The ethylenically unsaturated monomer of the present disclosure may have one or more functional groups having affinity for alkaline solutions.

[0031] The polymer particles of the present disclosure preferably contain a structural unit derived from the following general formula (1): This improves alkali solubility and tends to make the particles easier to remove.

[0032] [ka] (In general formula (1), R 1 represents an alkyl group having 1 to 4 carbon atoms, a hydrogen atom, an alkali metal atom, or ammonium.

[0033] Above R 1The alkyl group having 1 to 4 carbon atoms represented by the formula (I) is preferably an alkyl group having 1 to 2 carbon atoms, and more preferably an alkyl group having 1 carbon atom (methyl group).

[0034] R 1 The alkali metal atom represented by the formula (I) is preferably lithium, sodium or potassium, more preferably sodium or potassium, and even more preferably sodium.

[0035] R 1 Examples of the alkaline earth metal atom represented by the formula include calcium and magnesium.

[0036] R 1 Ammonium, represented by NH 4+ The term "organic ammonium" is defined to include, but is not limited to, organic ammonium. Examples of organic ammonium include quaternary ammonium such as tetraalkylammonium such as tetramethylammonium and tetrabutylammonium; and ammonium (primary to tertiary ammonium) formed by protonating amines. 1 The amine is preferably ammonia or ammonium formed by protonation of an amine. The amine is preferably a trialkylamine (preferably triC), such as trimethylamine, triethylamine, or tributylamine. 1-10 Alkylamines; hydroxyalkylamines such as diethanolamine and triethanolamine (preferably di- or tri(hydroxy C 1-10 alkylamines, etc.), and hydroxyalkylamines are preferred.

[0037] The structural unit represented by the general formula (1) may be formed by a polymerization reaction of a monomer represented by the following general formula (2), but may also be formed by other methods. For example, in the general formula (2), R 1 is an alkyl group having 1 to 4 carbon atoms, and then the resulting monomer is polymerized and hydrolyzed to obtain the compound represented by the general formula (1) 1may form an alkali metal structural unit, an alkaline earth metal structural unit, or an ammonium structural unit.

[0038] [ka] (In general formula (2), R 1 represents an alkyl group having 1 to 4 carbon atoms, a hydrogen atom, an alkali metal atom, or ammonium.

[0039] In the above general formula (2), R 1 R may be one type or two or more types. 1 When there are two or more types of monomers represented by the general formula (2), they may be formed by polymerizing two or more types of monomers represented by the general formula (2), 1 The ester group may be formed by polymerizing a monomer represented by the above general formula (2), in which R is an alkyl group having 1 to 4 carbon atoms, and then partially hydrolyzing the ester group or by hydrolyzing the ester group with two or more basic substances.

[0040] The alkali-soluble polymer particles of the present disclosure are preferably at least partially hydrolyzed.

[0041] The phrase "at least a portion of the alkali-soluble polymer particles of the present disclosure is hydrolyzed" means that the polymer is a partial hydrolyzate, a complete hydrolyzate, or a hydrolysis-neutralized product thereof. For example, in the case of methyl acrylate, CH═CH(—COO—CH), a partial hydrolyzate contains both structural units derived from CH═CH(—COO—CH) and CH═CH(—COO—H).

[0042] The alkali-soluble polymer particles of the present disclosure preferably contain 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and even more preferably 20% by mass or more of the structural unit represented by the general formula (1) relative to the total amount of the alkali-soluble polymer particles, while the content is preferably 99.9% by mass or less, more preferably 99% by mass or less, even more preferably 95% by mass or less, and even more preferably 90% by mass or less.

[0043] By including the AB agent in the above range, the alkali solubility of the particles is improved, and the AB agent tends to be easily removed.

[0044] The polymer particles having an alkali-soluble layer according to the present disclosure may have a multilayer structure, and may be, for example, core-shell particles composed of a core portion and a shell portion provided on the outside thereof, and further have an alkali-soluble layer.

[0045] The alkali-soluble layer of the alkali-soluble polymer particles of the present disclosure may have a multi-layer structure, and may be present in the outer layer or inner layer of the core-shell particle. Preferably, the alkali-soluble layer is present in the outermost shell.

[0046] The alkali-soluble layer contained in the alkali-soluble polymer particles of the present disclosure preferably contains 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more of the structural unit represented by the general formula (1) relative to the total amount of the alkali-soluble polymer particles, while the alkali-soluble layer preferably contains 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0047] <Structural units derived from other monomers> The alkali-soluble polymer particles of the present disclosure may contain one or more structural units derived from monomers other than structural units derived from ethylenically unsaturated monomers (hereinafter also referred to as "structural units derived from other monomers").

[0048] A structural unit derived from an other monomer refers to a structural unit in which at least one carbon-carbon double bond of the other monomer is replaced with a carbon-carbon single bond. For example, in the case of ethylene glycol diacrylate, CH═CH-CO-O-CHCHO-CO-CH═CH, a structural unit derived from ethylene glycol diacrylate can be represented by, for example, -CH-CH-CO-O-CHCHO-CO-CH-CH-. A structural unit derived from an other monomer can be formed, for example, by radical polymerization of the other monomer. Note that the structural unit derived from the other monomer may have the same structure as the structure in which the carbon-carbon double bond of the other monomer is replaced with a carbon-carbon single bond, and is not limited to a structural unit formed by polymerization of the other monomer, and may also be, for example, a structural unit formed by a reaction after polymerization.

[0049] The other monomers are not particularly limited, and examples thereof include (meth)acrylic monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate; styrene monomers such as styrene, α-methylstyrene, p-methylstyrene, tert-butylstyrene, chlorostyrene, and vinyltoluene; (meth)acrylic acid, Carboxyl group-containing monomers such as leic acid, fumaric acid, crotonic acid, itaconic acid, and maleic anhydride; silane group-containing monomers such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, 2-styrylethyltrimethoxysilane, vinyltrichlorosilane, γ-(meth)acryloyloxypropylhydroxysilane, and γ-(meth)acryloyloxypropylmethylhydroxysilane; 2-hydroxyethyl(meth)acryloyloxypropylmethylhydroxysilane; Hydroxyl group-containing monomers such as acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; nitrogen atom-containing monomers such as (meth)acrylamide, N,N-dimethyl (meth)acrylamide, dimethylaminoethyl (meth)acrylamide, N-vinylpyrrolidone, and (meth)acrylonitrile; ethylene glycol methoxy (meth)acrylate, diethylene glycol methoxy (meth)acrylate, and fluorine atom-containing monomers such as trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, and octafluoropentyl (meth)acrylate; epoxy group-containing monomers such as glycidyl (meth)acrylate; light-stabilizing monomers such as 2,2,6,6-tetramethylpiperidine-4-(meth)acrylate; ultraviolet absorbing monomers such as benzotriazole-based ultraviolet absorbing monomers and benzophenone-based ultraviolet absorbing monomers; and polyfunctional ethylenically unsaturated monomers.

[0050] The polyfunctional ethylenically unsaturated monomer is not particularly limited as long as it is a compound containing two or three or more ethylenic carbon-carbon double bonds, and examples thereof include compounds containing two or three or more ethylenic carbon-carbon double bonds of one or more types selected from a CH2=CH- group, a CH2=CH-O- group, a CH2=CH-CH2-O- group, a CH2=C(CH3)-CH2-O- group, a CH2=CH-CH2-CH2-O- group, a CH2=C(CH3)-CH2-CH2-O- group, a CH2=CH-CO-O- group, a CH2=C(CH3)-CO-O- group, and a CH2=CH-CO-NH- group.

[0051] The polyfunctional ethylenically unsaturated monomer preferably has a molecular weight of 50 or more and 1,000 or less, and more preferably 100 or more and 400 or less.

[0052] There are no particular limitations on the polyfunctional ethylenically unsaturated monomer, but it is preferably a polyfunctional ethylenically unsaturated monomer in which, with respect to the number n (n is an integer of 2 or more) of ethylenically unsaturated groups contained in one molecule of the polyfunctional ethylenically unsaturated monomer, n-1 or more are CH=CH-CO-O- groups or CH=CH-CO-NH- groups (hereinafter also referred to as a "hydrolyzable polyfunctional ethylenically unsaturated monomer").

[0053] Examples of the polyfunctional ethylenically unsaturated monomer include polyfunctional acrylic esters and N,N'-methylenebisacrylamide.

[0054] Specific examples of polyfunctional acrylic acid esters include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and acrylic-modified polydimethylsiloxane.

[0055] The polymer particles of the present disclosure preferably contain a structural unit derived from a polyfunctional acrylic acid ester as an additional monomer, which tends to improve the solubility of the polymer particles in an alkaline solution and make it easier to remove the AB agent.

[0056] The alkali-soluble polymer particles of the present disclosure may contain one or more structural units derived from polyfunctional ethylenically unsaturated monomers that are hydrolyzable in an alkaline solution.

[0057] The alkali-soluble polymer particles of the present disclosure preferably contain 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, even more preferably 2% by mass or more, and particularly preferably 5% by mass or more, of structural units derived from polyfunctional ethylenically unsaturated monomers hydrolyzable in alkaline solutions.On the other hand, the alkali-soluble polymer particles of the present disclosure preferably contain 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less, of structural units derived from polyfunctional ethylenically unsaturated monomers hydrolyzable in alkaline solutions.

[0058] [Method for producing the antiblocking agent of the present disclosure] <Polymerization method> The alkali-soluble polymer particles of the present disclosure can be obtained by polymerizing a monomer component containing, as an ethylenically unsaturated monomer, for example, a monomer represented by the above formula (2), and optionally other monomers, in an aqueous solvent, and then producing a partially or completely hydrolyzed polymer.

[0059] Examples of the polymerization method include suspension polymerization, emulsion polymerization, and dispersion polymerization. Among them, emulsion polymerization is preferred, in which the raw material monomer components are dispersed in a reaction solvent in the presence of an emulsifier and a (radical) polymerization reaction is carried out. Specifically, the method for producing the polymer of the present invention preferably includes emulsion polymerization, in which at least one monomer represented by formula (2) is dispersed in an aqueous solvent in the presence of an emulsifier and a polymerization reaction is carried out. The emulsion polymerization may be carried out in a single stage or in multiple stages.

[0060] The emulsifier may be one or more kinds, and may be a non-reactive surfactant or a reactive surfactant having a radically polymerizable group in its structure.

[0061] Non-reactive surfactants include anionic and nonionic surfactants. Examples of anionic surfactants include fatty acid salts, alkyl (aryl) sulfonates, alkyl sulfate ester salts, and polyoxyethylene alkyl (phenyl) ether sulfate salts. Examples of nonionic surfactants include polyoxyethylene alkyl (phenyl) ethers, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene fatty acid esters, and polyoxyethylene polyoxypropylene block polymers.

[0062] Reactive surfactants include anionic and nonionic surfactants. Examples of anionic reactive surfactants include, but are not limited to, ether sulfate reactive surfactants and phosphate ester reactive surfactants.

[0063] The amount of the emulsifier is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.3 parts by mass or more, relative to 100 parts by mass of the total of the raw material monomer components, and is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less.

[0064] In the present disclosure, the aqueous solvent may be water alone or a mixed solvent of water and a water-miscible organic solvent, with water alone being preferred. An aqueous solvent typically refers to a solvent with a water content of more than 50% by volume. Examples of water that can be used include ion-exchanged water (deionized water), distilled water, and pure water. Examples of water-miscible organic solvents that can be used include organic solvents that are uniformly miscible with water (such as lower alcohols). From the viewpoint of minimizing the amount of organic solvent remaining in the polymer, an aqueous solvent in which 80% by volume or more of the aqueous solvent is water is preferred, an aqueous solvent in which 90% by volume or more of the aqueous solvent is water is more preferred, an aqueous solvent in which 95% by volume or more of the aqueous solvent is water is even more preferred, an aqueous solvent essentially consisting of water (an aqueous solvent in which 99.5% by volume or more of water) is particularly preferred, and water alone is most preferred.

[0065] When polymerizing the raw material monomer components, means such as the use of a polymerization initiator, irradiation with ultraviolet rays or radiation, or application of heat are used. The use of a polymerization initiator is preferred, and from the viewpoint of efficiently reacting the raw material monomer components and sufficiently reducing the amount of residual monomer, a polymerization initiator in combination with an oxidizing agent and a reducing agent (redox type polymerization initiator) is preferred.

[0066] <Hydrolysis method> The alkali-soluble polymer particles of the present disclosure can be hydrolyzed by adding a basic aqueous solution such as an aqueous sodium hydroxide solution, an aqueous calcium hydroxide solution, an aqueous ammonia solution, or an aqueous cyclohexylamine solution.

[0067] The alkaline aqueous solution used for hydrolysis preferably has a pH of 7.0 or more and 14 or less. The concentration of the alkaline solution is preferably 0.1% by weight or more and 30% by weight or less. The amount of alkali used is preferably 0.01 mol or more and 200 mol or less relative to the total amount of structural units derived from the monomer. Furthermore, partial or complete neutralization can be performed by adding an acid to the hydrolysis solution as appropriate. By performing hydrolysis and neutralization, R in formula (1) can be obtained. 1 The group corresponding to R can be a hydrogen atom, an alkali metal atom, an alkali metal atom, or an ammonium atom. The amount of acid or base used during polymerization, hydrolysis, and neutralization can be adjusted, and R 1 The proportion of monomer units in which is a hydrogen atom can be adjusted.

[0068] [Uses of the antiblocking agent of the present disclosure] The polymer particles of the present disclosure may form a composition containing other components, including, but not limited to, dispersants, solvents, resins, crosslinking agents, antioxidants, and the like. The composition containing the polymer particles and resin of the present disclosure (hereinafter, sometimes referred to as a masterbatch) can be applied to a film to impart the polymer particles.

[0069] The masterbatch of the present disclosure has high affinity between the polymer particles and the resin, making it easy to adjust the blending amount and enabling the dispersibility of the polymer particles to be increased.

[0070] The content of polymer particles in the masterbatch of the present disclosure is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more, while it is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 5% by mass or less.

[0071] Examples of resins contained in the masterbatch of the present disclosure include polyester resins; polyolefin resins; polyamide resins; polyurethane resins; (meth)acrylic resins; polycarbonate resins; and polystyrene resins.

[0072] Examples of polyester resins include Nichigo Polyester (manufactured by Mitsubishi Chemical Corporation), Vylonal (manufactured by Toyobo Co., Ltd.), PES Resin (manufactured by Takamatsu Oil & Fat Co., Ltd.), and Pluscoat (manufactured by Goo Chemical Industry Co., Ltd.).

[0073] Examples of polyurethane resins include Superflex, a product name manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and Hydran, a product name manufactured by DIC Corporation.

[0074] Polyester resins are preferred, and water-based polyester resins having high affinity with water are more preferred.

[0075] The masterbatch of the present disclosure preferably contains 80% by mass or more of resin, more preferably 85% by mass or more, and even more preferably 90% by mass or more, while the masterbatch preferably contains 99.9% by mass or less of resin, more preferably 99% by mass or less, and even more preferably 95% by mass or less.

[0076] Examples of the crosslinking agent contained in the masterbatch of the present disclosure include a melamine-based crosslinking agent, an oxazoline-based crosslinking agent, an acrylamide-based crosslinking agent, a polyamide-based crosslinking agent, an epoxy-based crosslinking agent, an isocyanate-based crosslinking agent, an aziridine-based crosslinking agent, etc. An oxazoline-based crosslinking agent is preferred.

[0077] The crosslinking agent content in the masterbatch of the present disclosure is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass, while it is preferably 50% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0078] Examples of antioxidants contained in the masterbatch of the present disclosure include hindered phenol-based antioxidants, phosphorus-based antioxidants, lactone-based antioxidants, and hydroxyamine-based antioxidants.

[0079] Films using the masterbatch of the present disclosure are not particularly limited, and examples include films made from polyolefin resins such as polyethylene, polypropylene, and propylene-ethylene copolymer; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamide resins such as aliphatic polyamides such as nylon 6 and nylon 66; and aromatic polyamides such as polymetaxylylene adipamide; vinyl resins such as polystyrene, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, and ethylene-vinyl alcohol copolymer; acrylic resins such as homopolymers or copolymers of (meth)acrylic monomers such as polymethyl methacrylate and polyacrylonitrile; and cellophane. [Example]

[0080] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass."

[0081] <Volume average particle size> The polymer particle dispersion was diluted with ion-exchanged water and measured using a light scattering particle size distribution analyzer (Spectris' "Zetasizer Ultra") to determine the volume average particle diameter (nm) of the fine particles by dynamic light scattering.

[0082] <Alkali solubility evaluation> To 4 parts of a polymer particle dispersion prepared to a concentration of 10%, 1.5 parts of a 10% aqueous solution of sodium hydroxide was added and stirred for 12 hours using a stirrer. The volume average particle size was then measured using dynamic light scattering. The particle size of the polymer particles was evaluated as D1, and the particle size after alkali dissolution was evaluated as D2. The presence or absence of an alkali-soluble layer was confirmed based on the value of D1 - D2 according to the following criteria. D1-D2 is less than 10 nm; no alkali-soluble layer D1-D2 is 10nm or more; alkali-soluble layer present

[0083] <Blocking resistance evaluation> The coated surface of the film-formed sample A was attached to a static and dynamic friction tester (Trinity Labs "TL201S"), and a smooth PET film was used as the contact point between the load head (1 cm x 1 cm, 100 g) and the film-formed sample A. The sample was rubbed 10 times over a distance of 2 cm at a speed of 4 seconds per stroke. Blocking resistance was evaluated according to the following criteria. (Evaluation criteria) 〇: Static friction coefficient is less than 0.64 ×: Static friction coefficient is 0.64 or more

[0084] <Slipperiness evaluation> The film transportability was evaluated in the same manner as in the evaluation of blocking resistance, according to the following criteria. (Evaluation criteria) ○: Dynamic friction coefficient is less than 0.43 ×: Dynamic friction coefficient is 0.43 or more

[0085] <Evaluation of shedding> The coated surface of the film-formed sample B was attached to a static friction tester ("TL201S" manufactured by Trinity Labs) with aluminum foil at the contact point between the load head (1 cm x 1 cm, 10 g) and the film-formed sample B, and the sample was run back and forth over a distance of 10 cm at a speed of 20 seconds per run 10 times. The coated surface of the film-formed sample B after rubbing was observed with an electron microscope (JEOL Ltd., "JSM-7600FA") to observe the shape of the coated surface. The fall-off prevention property was evaluated according to the following criteria. (Evaluation criteria) ◯: No polymer particles fall off ×: Polymer particles are dropped off

[0086] <Anti-blocking agent (AB agent) removal evaluation> The film-formed sample A was immersed in a 1% aqueous solution of sodium hydroxide for 10 minutes, and then the film-formed sample was taken out and washed with a sufficient amount of ion-exchanged water, and the coating film was dried. Using a haze meter (NDH7000 manufactured by Nippon Denshoku Industries Co., Ltd.), the haze (%) was measured before and after treatment with the aqueous sodium hydroxide solution, and the difference in haze value due to the alkali treatment was calculated using the following formula. Haze value difference = (haze after alkali treatment) - (haze before alkali treatment) In addition, the coated surface of the film-formed sample A was observed with an electron microscope (JEOL Ltd., "JSM-7600FA") to observe the shape of the coated surface. The AB agent removal performance was evaluated comprehensively according to the following criteria. (Evaluation criteria) ◎: Haze value increased by 1% or more and particles were completely removed Good: The haze value increases by 1% or more, but some particles remain undissolved. ×: No increase in haze value was observed, and particles were not removed.

[0087] <Production Example A1> Into a stainless steel reactor equipped with a stirrer, thermometer, and cooler, 832.0 parts by mass of deionized water and 0.96 parts by mass of anionic reactive surfactant ADEKA REASOAP SR-20 (active ingredient 100% by mass, manufactured by ADEKA Corporation) diluted with ion-exchanged water to 25.0% by mass of active ingredient (hereinafter referred to as "SR-20 (active ingredient 25.0% by mass)") were added, and the internal temperature was raised to 75°C and maintained at that temperature. Meanwhile, in a vessel separate from the reactor, 2-hydroxymethyl acrylic 200.0 parts by mass of monomer composition A was prepared, which was composed of 170.0 parts by mass of methyl acrylate (hereinafter referred to as "RHMA"), 10.0 parts by mass of n-butyl acrylate (hereinafter referred to as "BA"), and 20.0 parts by mass of triethylene glycol diacrylate (hereinafter referred to as "3EG-A"). After the reactor was purged with nitrogen gas, 40.0 parts by weight of the monomer composition A, 21.0 parts by weight of hydrogen peroxide solution (hydrogen peroxide concentration 1.28% by weight), and 21.0 parts by weight of an L-ascorbic acid aqueous solution (L-ascorbic acid concentration 1.90% by weight) were added to the reactor to carry out an initial polymerization reaction. Next, the remaining 160.0 parts by weight of the monomer composition A, 479.0 parts by weight of hydrogen peroxide solution (hydrogen peroxide concentration 0.22% by weight), and 486.04 parts by weight of a mixture of 479.0 parts by weight of an L-ascorbic acid aqueous solution (L-ascorbic acid concentration 0.33% by weight) and 7.04 parts by weight of SR-20 (active ingredient 25.0% by weight) were uniformly added dropwise to the reactor from different inlets over a period of 4 hours. After the dropwise addition, the internal temperature was raised to 85°C and maintained at that temperature for 2 hours for aging, and then the reaction solution was cooled to obtain a polymer aqueous dispersion (A1a) in which the polymer (A1) was dispersed. The particle diameter of the obtained polymer particles (A1) was 380 nm. The resulting polymer particles (A1) were evaluated for alkali solubility by the above-mentioned method, and the particle size after alkali treatment was found to be 4 nm.

[0088] <Manufacturing example A2> In a stainless steel first reaction vessel equipped with a stirrer, thermometer, and cooler, 1,378 parts by mass of deionized water and 0.96 parts by mass of Adeka Reasoap SR-20 (active ingredient 10% by mass), an anionic reactive emulsifier mainly composed of an ether sulfate-type ammonium salt, were added, and the internal temperature was raised to 75°C and maintained at that temperature. Meanwhile, in a second reaction vessel different from the first reaction vessel, 105.0 parts by mass of methyl methacrylate (hereinafter referred to as "MMA") and 45.0 parts by mass of divinylbenzene 810 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., divinylbenzene purity 81%, hereinafter referred to as "DVB810") were added to prepare 150.0 parts by mass of Monomer Composition A. Furthermore, in a third reaction vessel different from the first and second reaction vessels, 45.0 parts by mass of RHMA and 5.0 parts by mass of 3EG-A were mixed to prepare 50.0 parts by mass of a monomer composition B. Next, after the atmosphere in the first reactor was replaced with nitrogen gas, 150 parts by weight of the monomer composition A, 20 parts by weight of hydrogen peroxide solution (concentration 3.35% by weight), and 20 parts by weight of an L-ascorbic acid aqueous solution (concentration 5.0% by weight) were added to the first reactor to carry out an initial polymerization reaction. Subsequently, 50 parts by weight of the monomer composition B, 100 parts by weight of hydrogen peroxide solution (concentration 0.83% by weight), 100 parts by weight of an L-ascorbic acid aqueous solution (concentration 1.25% by weight), and 100 parts by weight of a mixture of 7.04 parts by weight of SR-20 (active ingredient 10% by weight), 0.36 parts by weight of an ammonia aqueous solution (concentration 28% by weight), and 92.6% by weight of ion-exchanged water were uniformly added dropwise to the first reactor from different inlets over a period of 3 hours. After the dropwise addition, the internal temperature of the first reactor was maintained at 75°C and the mixture was aged for 2 hours. The reaction solution was then cooled to obtain a polymer aqueous dispersion (A2a) containing the polymer (A2). The particle diameter of the resulting polymer particles (A2) was 547nm. The resulting polymer particles (A2) were evaluated for alkali solubility by the above-mentioned method, and the particle size after alkali treatment was found to be 443 nm.

[0089] <Manufacturing example A3> A polymer particle aqueous dispersion (A3a) containing dispersed polymer particles (A3) was obtained in the same manner as in Production Example A2, except that monomer composition A was changed from 105 parts by weight of MMA and 45 parts by weight of DVB810 to 35 parts by weight of MMA and 15 parts by weight of DVB810, and monomer composition B was changed from 45 parts by weight of RHMA and 5 parts by weight of 3EG-A to 135 parts by weight of RHMA and 15 parts by weight of 3EG-A. The particle diameter of the obtained polymer particles (A3) was 436 nm. The resulting polymer particles (A3) were evaluated for alkali solubility by the above-mentioned method, and the particle size after alkali treatment was found to be 413 nm.

[0090] <Manufacturing example B1> A polymer particle aqueous dispersion (B1a) containing dispersed polymer particles (B1) was obtained in the same manner as in Production Example A2, except that the monomer composition B was changed from 45 parts by mass of RHMA and 5 parts by mass of 3EG-A to 45 parts by mass of RHMA and 5 parts by mass of DVB810. The particle diameter of the obtained polymer particles (B1) was 452 nm. The resulting polymer particles (B1) were evaluated for alkali solubility by the above-mentioned method, and the particle size after alkali treatment was found to be 556 nm, suggesting that the polymer particles (B1) did not have an alkali-soluble layer and absorbed an alkaline solution.

[0091] <Manufacturing example B2> A stainless steel reactor equipped with a stirrer, thermometer, and cooler was charged with 832.0 parts by mass of deionized water and 0.92 parts by mass of sodium dodecylbenzenesulfonate aqueous solution (6.5% by mass of active ingredient, hereinafter referred to as "DBSNa (6.5% by mass of active ingredient)"), and the internal temperature was raised to 75°C and maintained at that temperature. Separately, in a separate container, 140.0 parts by mass of MMA and 60.0 parts by mass of DVB810 were mixed to prepare 200.0 parts by mass of a monomer composition. Next, after the atmosphere inside the reactor was purged with nitrogen gas, 40.0 parts by mass of the monomer composition, 21.0 parts by mass of hydrogen peroxide solution (hydrogen peroxide concentration 1.28% by mass), and 21.0 parts by mass of an L-ascorbic acid aqueous solution (L-ascorbic acid concentration 1.90% by mass) were added to the reactor to carry out an initial polymerization reaction. Next, the remaining 160.0 parts by weight of the monomer composition, 479.0 parts by weight of hydrogen peroxide solution (hydrogen peroxide concentration 0.22% by weight), and 485.77 parts by weight of a mixture of 479.0 parts by weight of an L-ascorbic acid aqueous solution (L-ascorbic acid concentration 0.33% by weight) and 6.77 parts by weight of DBSNa (active ingredient 6.5% by weight) were added dropwise to the reactor from different inlets over a period of 4 hours. After the addition was completed, the internal temperature was raised to 85°C and maintained at that temperature for 2 hours for aging. The reaction solution was then cooled to obtain a crosslinked microparticle dispersion (B2a) in which crosslinked microparticles (B2) were dispersed. The particle diameter of the resulting polymer particles (B2) was 493 nm. The resulting polymer particles (B2) were evaluated for alkali solubility by the above method, and the particle size after alkali treatment was found to be 489 nm. The polymer particles (B2) did not have an alkali-soluble layer.

[0092] <Production Example B3> A 10 L glass reactor equipped with a stirrer, a dropping device, and a thermometer was charged with 4266.5 g of methyl alcohol as an organic solvent and 333.0 g of 28 wt % ammonia water (water and catalyst), and the liquid temperature was adjusted to 20±0.5°C while stirring. Meanwhile, a solution of 333.0 g of tetramethoxysilane as a silicon compound dissolved in 533.0 g of methyl alcohol was charged to the dropping device. The solution was then added dropwise from the dropping device over 1 hour. After the dropwise addition, the mixture was stirred for another 1 hour to hydrolyze and condense the tetramethoxysilane, yielding a suspension (B3a) of silica microparticles (B3). The particle diameter of the resulting polymer particles (B3) was 374 nm. The alkali solubility of the resulting polymer particles (B3) was evaluated using the above method, and the particle diameter after alkali treatment was 384 nm. The polymer particles (B3) did not have an alkali-soluble layer.

[0093] [resin] The following resins were used to be blended with the aqueous dispersion of polymer particles. (Water-based polyester resin) Nichigo Polyester WR-901: Mitsubishi Chemical Corporation, solid content 19.9% ​​by mass

[0094] [Example 1] <Preparation of film-formed sample A> A water-based polyester resin (Nichigo Polyester WR-901) and a polymer aqueous dispersion (A1a) were mixed in a solids ratio of 100:10, and then thoroughly stirred with a stirrer to obtain coating composition A-(1). Coating composition A-(1) was then applied to a transparent polyethylene terephthalate film (hereinafter referred to as "PET film"; Toyobo Co., Ltd., Cosmoshine A4300, length: 297 mm, width: 210 mm, thickness: 0.100 mm) using a bar coater to a coating thickness of 52 μm. The film was then dried at 100°C for 10 minutes in a constant-temperature oven (Yamato Scientific Co., Ltd., "DNF400") to obtain coating sample A-(1). The coating sample A-(1) was evaluated for blocking resistance, slipperiness, and AB agent removability.

[0095] <Preparation of film-forming sample B> Coating composition B-(1) was prepared in the same manner as film-forming sample A-(1), except that the resin and the aqueous polymer particle dispersion were mixed in a solids ratio of 100:20. Next, coating composition B-(1) was applied to a transparent polyethylene terephthalate film (hereinafter referred to as "PET film"; Toyobo Co., Ltd., Cosmoshine A4300, length: 297 mm, width: 210 mm, thickness: 0.100 mm) using a bar coater to a coating thickness of 7 μm. The film was then dried at 100°C for 10 minutes in a constant-temperature oven (Yamato Scientific Co., Ltd., "DNF400") to obtain film-forming sample B-(1) with a laminated coating. The peelability of film-forming sample B-(1) was evaluated.

[0096] [Examples 2 to 3, Comparative Examples 1 to 3] Film-forming samples were prepared and evaluated in the same manner as in Example 1, except that the types of resin and polymer aqueous dispersion to be blended were changed to those shown in Table 1.

[0097] [Reference example 1] The PET film used as the film substrate (Cosmoshine A4300, manufactured by Toyobo Co., Ltd., length: 297 mm, width: 210 mm, thickness: 0.100 mm) was evaluated alone. The static friction coefficient was 0.43, and the dynamic friction coefficient was 0.64.

[0098] [Table 1]

[0099] [Table 2]

[0100] The results in Tables 1 and 2 reveal that the antiblocking agent of the present disclosure has the ability to prevent the antiblocking agent from falling off from the film and can be easily removed with an alkaline solution.

Claims

1. An antiblocking agent comprising polymer particles having an alkali-soluble layer, the polymer particles comprising a structural unit represented by the following general formula (1) and a structural unit derived from a polyfunctional acrylate ester, and the alkali-soluble layer has a thickness of 10 nm or more: 【Chemistry 1】 (In general formula (1), R 1 represents an alkyl group having 1 to 4 carbon atoms, a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, or ammonium.)

2. 2. The antiblocking agent according to claim 1, wherein the polymer particles having the alkali-soluble layer have a volume average particle size of 10 nm to 10 μm.

3. A masterbatch comprising the antiblocking agent according to claim 1 or 2 and a resin.

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