Surface-treated plastic film

Abstract

To provide a plastic film which remarkably improves writing property, and prevents a dusting phenomenon.SOLUTION: There is provided a surface-treated plastic film in which a surface coating layer is formed on at least one surface of a base material plastic film, wherein the surface coating layer is a layer obtained by curing a surface coating layer formative composition containing a binder composition (A) and inorganic particles (B), the binder composition (A) contains a polyester resin and a melamine compound, a content of the inorganic particles (B) in 100 mass% of the total solid content of the surface coating layer formative composition is 20 mass% or more and 40 mass% or less, a coefficient (μs) of static friction when the surface coating layers are rubbed with each other is 0.65 or less, surface roughness (Ra) of the surface coating layer is more than 1.6 μm and 4.0 μm or less, and a maximum projection height (Rz) thereof is more than 20 μm and 40 μm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a surface-treated plastic film. In particular, the present invention relates to a plastic film useful for various labels, cards, delivery slips, recording paper for printers, etc., which has dramatically improved suitability for stamping and writing, and is free from powder shedding. [Background technology]

[0002] Compared to natural paper, plastic films are superior in water resistance, moisture absorption dimensional stability, flatness, gloss and clarity of printed matter, and mechanical strength, etc. Therefore, they are widely used as synthetic paper to replace natural paper in fields such as packaging paper, labels, maps, posters, various cards such as business cards, delivery slips, and recording paper for various printers.

[0003] In recent years, electrophotographic printing has become increasingly popular due to its simplicity and the improved image quality of printed materials. In electrophotographic printing, printing is performed by transferring and fixing toner, which is fine particles made of resin dispersed with pigments and various additives, onto a film, and in this case, the fixability of the toner to the film is important.

[0004] For example, Patent Document 1 discloses a surface-treated plastic film having a toner-adhesive layer on a substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-345051 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the surface-treated plastic film disclosed in Patent Document 1 tends to have low surface roughness. Furthermore, in recent years, as printing speeds have increased, when sheets or continuous sheets are folded and the printed surfaces come into contact with each other, a problem known as toner transfer occurs, in which toner is transferred to the opposing surface due to impact such as friction. For example, when a surface-treated plastic film such as that disclosed in Patent Document 1 is used and the sheets are folded and the printed surfaces come into contact with each other, there is a risk of toner transfer occurring. Furthermore, in recent years, there has been a demand for printability on plastic films in order to replace paper. When stamping on a surface-treated plastic film such as that described in Patent Document 1, there is a risk that the letters will bleed over time and be crushed when rubbed with a finger or an object. Furthermore, plastic films are required to have properties that distinguish them from other plastic films depending on their applications.

[0007] The present invention has been made in consideration of the above-mentioned situation, and aims to provide a surface-treated plastic film that has good toner fixing properties, does not cause toner transfer, can be used for stamping, and can be distinguished from other types of plastic cards by feel. [Means for solving the problem]

[0008] That is, the present invention comprises the following: [1] A surface-treated plastic film having a surface coating layer formed on at least one surface of a base plastic film, the surface coating layer is a layer obtained by curing a surface coating layer-forming composition containing at least a binder composition (A) and inorganic particles (B), the content of the inorganic particles (B) in 100% by mass of the total solid content of the surface coating layer-forming composition is 20% by mass or more and 40% by mass or less; The static friction coefficient (μs) when the surface coating layers are rubbed against each other is 0.65 or less, The surface-treated plastic film has a surface roughness (Ra) of the surface coating layer exceeding 1.6 μm and not exceeding 4.0 μm, and a maximum projection height (Rz) of more than 20 μm and not exceeding 40 μm. [2] In one embodiment, the surface-treated plastic film contains a wax component as an additive in an amount of 0% by mass or more and 10.0% by mass or less based on the total solid content of the surface coating layer-forming composition that forms the surface coating layer. [3] In one embodiment, the surface-treated plastic film has a binder composition (A) containing at least a polyester resin, and the content of the polyester resin in 100% by weight of the total solid content of the binder composition (A) is 25% by mass or more and 100% by mass or less. [4] In one embodiment, the surface-treated plastic film comprises inorganic particles (B) containing at least particles (B1) having an average particle size of 0.1 μm or more and less than 5.0 μm and particles (B2) having an average particle size of 5.0 μm or more and 20.0 μm or less, The mass ratio of B1:B2 is 60:40 to 10:90. [5] In one embodiment, the surface-treated plastic film has a base plastic film that is a polyester film. [6] In one embodiment, the surface-treated plastic film has a substrate plastic film that is a white polyester film containing voids. [7] In one embodiment, the surface-treated plastic film has a base plastic film that is a polyester film or a white polyester film containing voids, and contains 25% by mass or more and 90% by mass or less of polyester resin made from recycled raw materials such as film scraps and PET bottles relative to the total polyester resin constituting the polyester film or the white polyester film containing voids. [Effects of the Invention]

[0009] The surface-treated plastic film of the present invention has better toner fixability than conventional films, does not cause toner transfer, and can be used for imprinting.Furthermore, it can be distinguished from other types of plastic cards by touch. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below. (Base plastic film) In the present invention, the plastic film constituting the substrate film can be, for example, a variety of polymer films made of polyolefin, polyester, polyamide, polyimide, polycarbonate, polystyrene, polymethacrylate, polyvinyl chloride, etc., of which polyester films are particularly preferred in terms of heat resistance, strength, stiffness, etc. There are no particular restrictions on the thickness of these substrate films, but in order to ensure the general strength characteristics required for synthetic paper, etc., it is preferably 1 to 500 μm, more preferably 10 to 300 μm.

[0011] The polyester resin that is the main component of polyesters suitable for use as base film materials is a polymer synthesized from a dicarboxylic acid or its ester-forming derivative and a diol or its ester-forming derivative. Representative examples of such polyester resins include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polyethylene-2,6-naphthalate, with polyethylene terephthalate being preferred from the standpoints of mechanical properties, heat resistance, cost, etc.

[0012] These polyester resins may also be copolymerized with other components as long as the objectives of the present invention are not impaired. Specific examples of copolymerization components include dicarboxylic acid components such as isophthalic acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, adipic acid, sebacic acid, and their ester-forming derivatives. Examples of diol components include diethylene glycol, hexamethylene glycol, neopentyl glycol, and cyclohexanedimethanol. Other examples include polyoxyalkylene glycols such as polyethylene glycol and polypropylene glycol. The copolymerization amount is preferably within 10 mol %, more preferably within 5 mol %, per constituent repeating unit.

[0013] The polyester resin of the present invention can be produced by, for example, first carrying out an esterification or transesterification reaction using the above-mentioned dicarboxylic acid or its ester-forming derivative and the diol or its ester-forming derivative as main starting materials in a conventional manner, followed by a polycondensation reaction at high temperature and reduced pressure.

[0014] The intrinsic viscosity of the polyester resin pellets of the present invention is preferably in the range of 0.50 to 0.9 dL / g, more preferably in the range of 0.55 to 0.85 dL / g. Such an intrinsic viscosity improves film-forming properties and recyclability, which is preferable since it facilitates stable film production operations.

[0015] The polyester resin in the present invention may include polyester resin recycled from PET bottles. The crystallinity of the polyester used in PET bottles is controlled to improve bottle moldability and appearance. As a result, polyesters containing 0.5 mol % to 10.0 mol % of isophthalic acid components and ester constituent units derived from any diol component, such as ethylene glycol or diethylene glycol, relative to the total ester constituent units in the polyester resin may be used. Furthermore, polyesters with increased intrinsic viscosity may be used by further solid-phase polymerization after liquid-phase polymerization. Polyester resin pellets recycled from PET bottles are usually obtained by washing, pulverizing, heat-melting, and re-pelletizing the PET bottles, but those with increased intrinsic viscosity by further solid-phase polymerization may also be used. The intrinsic viscosity of polyester-based resins recycled from PET bottles is preferably in the range of 0.60 to 0.75 dL / g. When the intrinsic viscosity is 0.60 dL / g or higher, the resulting film is less likely to break, making film production easier and more stable. On the other hand, when the intrinsic viscosity is 0.75 dL / g or lower, the increase in filtration pressure of the molten fluid is prevented from becoming too large, making film production easier and more stable. Generally, when polyethylene terephthalate resin is polymerized in a solid phase, the amount of oligomers contained in the resin, especially the PET cyclic trimer, which has the highest content, is lower than that of resins polymerized in a liquid phase. The upper limit of the cyclic trimer oligomer content in polyester-based resins recycled from PET bottles is preferably 0.7% by mass, more preferably 0.5% by mass, and even more preferably 0.4% by mass.

[0016] In one embodiment, the base plastic film is a polyester film or a polyester film containing voids, and can contain 25% by mass or more and 90% by mass or less of polyester resin made from recycled raw materials such as film scraps and PET bottles relative to the total polyester resin constituting the polyester film or white polyester film containing voids. For example, the void-containing polyester film may be a white polyester film. In one embodiment, the content of polyester resin recycled from PET bottles and polyester resin composed of film scraps in the void-containing polyester film is preferably 25% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more, based on the total polyester resin constituting the polyester film. A content of 25% by mass or more is preferred because it reduces the amount of oligomers contained in the void-containing polyester film and can suppress oligomer precipitation. Furthermore, in terms of utilizing recycled resins, a high content is preferred in terms of contributing to reducing environmental impact. The content of polyester resin recycled from PET bottles is preferably 90% by mass or less, more preferably 85% by mass or less.

[0017] The surface-treated film of the present invention, obtained by applying the above-mentioned surface coating to at least one side of the above-mentioned substrate film, may use a white polyester film as the substrate film to enhance its suitability as synthetic paper. In this case, the light transmittance should be 30% or less, preferably 20% or less, and more preferably 15% or less. A light transmittance of 30% or less is preferable because the back side cannot be seen through and there is no risk of impairing the appearance after printing.

[0018] Furthermore, when selecting and using a base polyester film, a material containing polyester as the film material and one or more thermoplastic resins incompatible with the polyester is used, and after forming the film, the film is stretched at least uniaxially, preferably biaxially in the longitudinal and transverse directions, to form numerous microvoids within the film and achieve an apparent specific gravity of 0.8 to 1.3, which is extremely suitable as a base film. Of course, a white polyester film, and a void-containing polyester film, is particularly preferred.

[0019] Specifically, the thermoplastic resin incompatible with polyester used in this process is incorporated as a void-forming agent to form fine voids in the polyester film, thereby enhancing flexibility, lightness, and drawability. Any resin incompatible with polyester can be used without particular limitations. Examples include polystyrene-based resins, polyolefin-based resins, cyclic polyolefin-based resins, polyacrylic resins, polycarbonate resins, and polysulfone-based resins. Among these, polystyrene-based resins and polyolefin-based resins such as polymethylpentene and polypropylene are particularly preferred. The amount of these incompatible resins incorporated into the polyester varies depending on the desired amount of voids to be formed in the substrate film, but a ratio of 3 to 40% by mass of the film material is generally preferred, with 5 to 15% by mass being particularly preferred. A content of 3% by mass or more significantly enhances the void formation effect, improving the flexibility, lightness, and drawability of the substrate film. On the other hand, a content of 40% by mass or less is preferred because it prevents the film from impairing its stretchability and maintains its heat resistance, strength, and stiffness. The above cavity generating agents may be used alone or in combination of two or more.

[0020] The void-containing film preferably has an apparent specific gravity of 0.8 to 1.3, more preferably 1.0 to 1.25, and even more preferably 1.05 to 1.25. An apparent specific gravity of 0.8 or more is preferable because the strength of the film is maintained and there is no risk of cracks or wrinkles on the surface of the film. On the other hand, an apparent specific gravity of 1.3 or less is preferable because cushioning properties are maintained and drawing with a pencil or the like is also good.

[0021] In the present invention, the microvoid-containing polyester film preferably used as the substrate film may be a single-layer film, or may of course be a composite film of two or more layers depending on the application.

[0022] Inorganic or organic particles may be added to the substrate film as needed to improve hiding power, etc. Examples of particles that can be added include silica, kaolinite, talc, calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, titanium oxide, and organic particles such as benzoguanamine particles, crosslinked polystyrene particles, and crosslinked acrylic particles. The method for producing the plastic film of the present invention is not particularly limited, but most commonly, an oriented film obtained by biaxial stretching is preferably used. That is, this method involves stretching an unstretched plastic sheet obtained by melt extrusion 2 to 10 times in the machine direction, then further stretching 2 to 10 times in the transverse direction, and then heat-treating to complete the orientation and crystallization.

[0023] A corona treatment layer or an easy-adhesion layer may be provided on the surface of the substrate film to improve adhesion with the surface coating layer. Coating methods are commonly used to form the easy-adhesion layer, and specific examples include gravure coating, kiss coating, dip coating, spray coating, curtain coating, air knife coating, blade coating, and reverse roll coating. Any method may be used for coating, such as coating before film stretching, coating after longitudinal stretching, or coating on the surface of a film after orientation treatment. However, the most preferred method for improving adhesion of the coating layer is an in-line coating method, in which a coating liquid is applied to at least one side of a uniaxially stretched substrate film by the above-mentioned coating method, and then the film is further stretched in a direction perpendicular to the previous uniaxial stretching method.

[0024] The resin used in the easy-adhesion layer is not particularly limited, but preferably contains one, two, or three of an acrylic, polyester, or urethane composition. If necessary, the coating composition for the easy-adhesion layer may contain a crosslinking agent.

[0025] (Surface coating layer) The present invention is a surface-treated plastic film having a surface coating layer formed on at least one side of a base plastic film, wherein the surface coating layer is a layer formed by hardening a surface coating layer-forming composition containing at least a binder composition (A) and inorganic particles (B), and the content of inorganic particles (B) in 100% by mass of the total solids content of the surface coating layer-forming composition that forms the surface coating layer is 20% by mass or more and 40% by mass or less, the static friction coefficient (μs) when the surface coating layers are rubbed against each other is 0.65 or less, the surface roughness (Ra) of the surface coating layers is more than 1.6 μm and less than 4.0 μm, and the maximum protrusion height (Rz) is more than 20 μm and less than 40 μm.

[0026] (Binder composition (A)) Examples of the binder composition (A) used in the present invention include polyester resin, acrylic resin, urethane resin, melamine resin, and styrene resin. Mixtures of these resins with other resins can also be used. For example, other resins include polyvinyl alcohol, which is effective in improving particle dispersibility and adhesion to the resin. Considering the particle dispersibility and adhesion to the resin of the surface coating layer, polyester resin is preferably used as the binder composition.

[0027] From the viewpoint of increasing the surface hardness of the surface coating layer, preferred binder compositions (A) include acrylic resins, urethane resins, and melamine compounds, with urethane resins and melamine compounds being particularly preferred, and melamine compounds being most preferred.

[0028] The polyester resin may be a linear one, but is more preferably a polyester resin containing a dicarboxylic acid and a diol having a branched structure as its constituent components. The dicarboxylic acid referred to here includes, as its main component, terephthalic acid, isophthalic acid, or 2,6-naphthalenedicarboxylic acid, as well as aliphatic dicarboxylic acids such as adipic acid and sebacic acid, and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and 2,6-naphthalenedicarboxylic acid. Furthermore, the branched glycol refers to a diol having a branched alkyl group, and examples thereof include 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2-methyl-2-butyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3-propanediol, 2-methyl-2-n-hexyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl-2-n-hexyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, 2-n-butyl-2-propyl-1,3-propanediol, and 2,2-di-n-hexyl-1,3-propanediol.

[0029] The polyester resin preferably contains the branched glycol component, which is a more preferred embodiment of the present invention, at a ratio of 10 mol % or more, and more preferably 20 mol % or more, of the total glycol components. If the ratio is 10 mol % or less, the crystallinity may be high, and the adhesiveness of the coating layer may decrease. The upper limit of the glycol component content of the total glycol components is preferably 80 mol % or less, and more preferably 70 mass %. If the ratio is 80 mol % or more, the concentration of oligomers, which are by-products, may increase, which may affect the transparency of the coating layer. Ethylene glycol is the most preferred glycol component other than the above compounds. Small amounts of diethylene glycol, propylene glycol, butanediol, hexanediol, 1,4-cyclohexanedimethanol, etc. may also be used.

[0030] The dicarboxylic acid constituting the polyester resin is most preferably terephthalic acid or isophthalic acid. In addition to the dicarboxylic acids, 5-sulfoisophthalic acid or the like is preferably copolymerized in a range of 1 to 10 mol % to impart water dispersibility to the copolymerized polyester resin. Examples include sulfoterephthalic acid, 5-sulfoisophthalic acid, and 5-sodium sulfoisophthalic acid. A polyester resin containing a dicarboxylic acid having a naphthalene skeleton may also be used, but to prevent a decrease in ink adhesion, the quantitative proportion of the dicarboxylic acid is preferably 5 mol % or less of the total carboxylic acid components, and it may not be used at all.

[0031] Examples of acrylic resins include, but are not limited to, those having a hydroxyl group, a methylol group, an ethylol group, a butyrol group, an alkoxymethyl group, an alkoxyethyl group, an alkoxybutyl group, an epoxy group, an imino group, or the like in the main chain and / or side chain.

[0032] Examples of urethane resins include various polyurethane resins, polyurethane polyurea resins, and prepolymers thereof. Specific examples of such urethane resins include reaction products of diisocyanate components such as tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, and dicyclohexyl diisocyanate with diol components such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, bisphenol, polyester diol, polyether diol, polycarbonate diol, and polyethylene glycol; and reaction products of urethane prepolymers having isocyanate groups at their terminals with amino compounds, aminosulfonates, polyhydroxycarboxylic acids, and bisulfites. A catalyst can also be used to increase reactivity.

[0033] The melamine compound is a compound having a melamine skeleton within the compound. Examples of suitable compounds include alkylolated melamine derivatives, compounds obtained by reacting alkylolated melamine derivatives with alcohols to partially or completely etherify them, and mixtures thereof. Suitable alcohols for etherification include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, and isobutanol. The melamine compound may be a monomer or a dimer or higher polymer, or a mixture thereof. Furthermore, melamine may be partially co-condensed with urea or the like, and a catalyst may be used to increase the reactivity of the melamine compound.

[0034] The content of the binder composition (A) is preferably 40% by mass or more and 75% by mass or less, relative to 100% by mass of the total solids content of the surface coating layer-forming composition that forms the surface coating layer. It is more preferably 45% by mass or more and 70% by mass or less. A content of 40% by mass or more is preferred because it prevents the inorganic particles from falling off and reduces the static friction coefficient. A content of 45% by mass or more is preferred because it further reduces the static friction coefficient and prevents toner transfer. A content of 75% by mass or less is preferred because it prevents excessive coating of the inorganic particle components and improves resistance to bleeding and rubbing of the imprint. A content of 70% by mass or less is even more preferred because it further suppresses coating of the particle components and improves resistance to bleeding and rubbing of the imprint.

[0035] The content of polyester resin in binder composition (A) may not be used at all, but is preferably 25% by mass or more and 100% by mass or less of the total solid content of binder composition (A). It is more preferably 50% by mass or more and 100% by mass or less. When the content of polyester resin is 25% or more, toner fixation after printing tends to improve. When it is 50% by mass or more, toner fixation is further improved, and the toner can be used for a long time after printing without reprinting.

[0036] (Inorganic particles (B)) Examples of inorganic particles (B) used in the surface coating layer of the present invention include, but are not limited to, silica, kaolinite, talc, calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, and titanium oxide. Among these, silica and calcium carbonate are particularly preferred. These inorganic particles are preferably a combination of particles (B1) having an average particle size of 0.1 μm or more and less than 5.0 μm and particles (B2) having an average particle size of 5.0 μm or more and 20.0 μm or less. More preferably, inorganic particles B1 have an average particle size of 1.0 μm or more and less than 4.0 μm, and inorganic particles B2 have an average particle size of 7.5 μm or more and 18.0 μm or less, e.g., an average particle size of inorganic particles B2 of 9.0 μm or more and 18.0 μm or less. If the average particle diameter of inorganic particles B1 is 0.1 μm or more, even when the inorganic particle ratio described below is 20% by mass, they are not too embedded in the resin, making it possible to adjust the surface roughness to the desired range. Furthermore, if the average particle diameter is less than 5.0 μm, it is an appropriate particle size for forming small irregularities that suppress imprint bleeding, and is therefore preferred. If the average particle diameter of inorganic particles B2 is 5.0 μm or more, it is possible to adjust the maximum surface protrusion to the desired range, and this improves imprint rubbing and toner transfer evaluation, making it preferred. If the average particle diameter of inorganic particles B2 is 7.5 μm or more, it further increases the maximum surface protrusion height, improving the above effects and making the surface of the surface coating layer feel rough, making it even more preferred. If the average particle diameter is 20 μm or less, it is possible to prevent detachment from the surface coating layer and ensure reliable heat transfer to the resin surface during printing toner fixation, making it even more preferred.

[0037] The mass ratio of inorganic particles B1 to B2 is preferably B1:B2=60:40 to 10:90. When the ratio of B1 is 10 or more, the small irregularities bind the printing ink, preventing printing bleeding. When the ratio is 60 or less, the number of particles that scrape the toner is not too large, allowing toner transfer to be maintained at a good level. If the B2 ratio is 40 or more, the larger particles will contact the toner on the other side, reducing the contact area between the toner and the particles, allowing for good toner transfer. Furthermore, a higher maximum protrusion height is preferable because it reduces contact with the ink surface and prevents rubbing during the stamping rubbing evaluation described below. A ratio of 90 or less is preferable because it reduces contamination of the film surface and the inside of the device due to particle shedding. In one embodiment, the mass ratio of inorganic particles B1 to B2 is B1:B2=55:45 to 15:85, and for example, the content of inorganic particles B2 may be greater than the content of inorganic particles B1, and the mass ratio of inorganic particles B1 to B2 may be B1:B2=15:85 or more.

[0038] The inorganic particles (B) may be surface-treated with an organic compound or a silicon compound having an organic moiety in the molecule. In particular, when a non-aqueous medium is used, it is preferable to use inorganic particles (B) that have been surface-treated with an organic substance.

[0039] The inorganic particles (B) can be used in combination with organic particles, such as benzoguanamine particles, crosslinked polystyrene particles, and crosslinked acrylic particles.

[0040] The content of inorganic particles (B) in 100% by mass of the total solids content of the surface coating layer-forming composition that forms the surface coating layer is preferably 20% by mass or more and 40% by mass or less. More preferably, it is 21% by mass or more and 38% by mass or less. Even more preferably, it is 22% by mass or more and 36% by mass or less. When it is 20% by mass or more, the amount of inorganic particles that absorbs the printing ink is sufficient, and evaluations of printing bleeding and printing rubbing are improved, which is preferable. A content of 21% by mass or more or 22% by mass or more is preferable because it further improves printing performance. A content of 40% by mass or less is preferable because it reduces the amount of inorganic particles that scrape the toner layer, making toner transfer less likely to occur. A content of 40% by mass or less or 38% by mass or less or 36% by mass or less can more effectively suppress toner transfer, making it preferable.

[0041] The inorganic particles (B) may be directly added to a coating material prepared by adjusting the binder composition (A), the optional functional composition (C), and the aqueous medium. For example, a dispersion process is preferably performed after adding the inorganic particles to eliminate coarse inorganic particles and obtain the desired dispersed particle size. It is also more preferable to prepare a masterbatch of inorganic particles in advance to obtain the desired dispersed particle size in a short period of time. Examples of devices that can be used to disperse inorganic particles include ball mills, sand mills, attritors, roll mills, agitators, colloid mills, ultrasonic homogenizers, homomixers, dissolvers, pearl mills, wet jet mills, paint shakers, butterfly mixers, planetary mixers, and Henschel mixers. The average particle size of the dispersed particles is preferably a 50% volume mean diameter (Dv50) of 0.05 or more. A Dv50 of 0.05 μm or more is preferred because Ra and S are not too small.

[0042] The surface coating layer-forming composition that forms the surface coating layer can contain, in addition to the binder composition (A), a functional composition (C). The effects of the functional composition (C) are not particularly limited, but examples thereof include the effect of preventing particles from falling off the surface coating layer, the effect of preventing double feeding of films during printing, and the effect of improving liquid stability during processing.

[0043] For example, to prevent particles from falling off the surface coating layer, slipperiness can be imparted to the particles to prevent localized loads. Examples of compositions with such a function include wax. The surface coating layer of the present invention preferably contains a wax component in an amount of 0 to 10.0% by mass. In addition to achieving the above-mentioned effects, the inclusion of a wax component also reduces the static friction coefficient and is effective in suppressing toner transfer. Furthermore, if the wax component is 10.0% by mass or less, the particles are not overcoated, and bleeding or rubbing of the imprint can be prevented from being significantly affected. For example, the wax component can be contained in an amount of 0.5% by mass or more and 10.0% by mass or less. Examples of waxes include various ester waxes, low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene, silicones that exhibit a softening point upon heating, fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide, vegetable waxes such as carnauba, rice wax, candelilla wax, Japan wax, and jojoba oil, animal waxes such as beeswax, mineral and petroleum waxes such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax, and modified products thereof.

[0044] For example, in order to prevent double feeding of films during printing, antistatic properties can be provided to the surface coating layer to eliminate electrostatic adhesion between films. One method for providing antistatic properties is to use a general coating-type antistatic agent as the functional composition (C). Examples of the antistatic agent include low molecular weight surfactant-type antistatic agents, polymer-type antistatic agents, etc. Examples of the low molecular weight surfactant-type antistatic agents include cationic antistatic agents having cationic groups such as quaternary ammonium salts, pyridinium salts, and primary to tertiary amino groups, anionic antistatic agents having anionic groups such as sulfonate groups, sulfate groups, and phosphate groups, amphoteric antistatic agents such as amino acid antistatic agents and amino sulfate ester antistatic agents, and nonionic antistatic agents such as amino alcohol antistatic agents, glycerin antistatic agents, and polyethylene glycol antistatic agents. Examples of polymer-type antistatic agents include nonionic polymer-type antistatic agents such as polyethylene oxide, polypropylene oxide, polyethylene glycol, polyether ester amide, polyether ester, polyether polyolefin, and ethylene oxide-epichlorohydrin copolymers; anionic polymer-type antistatic agents such as polystyrene sulfonic acid; and cationic polymer-type antistatic agents such as quaternary ammonium base-containing acrylate polymers, quaternary ammonium base-containing styrene polymers, and quaternary ammonium base-containing polyethylene glycol methacrylate copolymers.

[0045] For example, to improve the liquid stability during processing, it is necessary to prevent the precipitation of particles dispersed in the liquid, and a particle dispersant can be used as the functional composition (C). By improving the liquid stability during processing, the desired surface shape and performance of the surface coating layer can be stably obtained, so it is preferable to use a particle dispersant.

[0046] Although the particle dispersant is not particularly limited, an acrylic acid-based inorganic particle dispersant is preferred. If an acrylic acid-based inorganic particle dispersant is used, the liquid stability is further improved and the desired surface shape and performance can be obtained.

[0047] The content of the dispersant is preferably 0.1% by mass or more and 1.5% by mass or less, based on 100% by mass of the total solids content of the surface coating layer-forming composition that forms the surface coating layer. It is more preferably 0.3% by mass or more and 1.2% by mass or less. A content of 0.1% by mass or more improves the stability of the liquid, which is preferable. A content of 0.3% by mass or more further improves the stability of the liquid, which is more preferable. Furthermore, a content of 1.5% by mass or less is preferable because it does not deteriorate the toner fixation during printing. A content of 1.2% by mass or less is preferable because, in addition to the above performance, it does not deteriorate the stamping performance.

[0048] The surface coating layer-forming composition that forms the surface coating layer does not necessarily contain the functional composition (C), but if it does contain it, it is preferable to limit it to a level that does not interfere with the functions of the binder composition (A) and the inorganic particles (B). Specifically, the content of the functional composition (C) is preferably 20% by mass or less, based on 100% by mass of the total solids content of the surface coating layer-forming composition that forms the surface coating layer. Within this range, the functions of the binder composition (A) and the inorganic particles (B) are not interfered with, which is preferable.

[0049] The binder composition (A) and the functional composition (C) can be used in any state of water-soluble, water-insoluble or aqueous dispersion as long as their effects are not lost, but considering the dispersibility of inorganic particles described later, it is preferable to make the entire coating agent aqueous, so it is preferable to use them in the state of water-soluble or aqueous dispersion.When used in an aqueous system, in addition to water, alcohols such as methanol, ethanol, isopropyl alcohol, and organic solvents can be used as long as they do not inhibit the reactivity and solubility of the resin.

[0050] The functional composition (C) can be directly added to the coating solution to be contained therein, or can be mixed into a master batch of the inorganic particles (B) to be contained in the coating solution.

[0051] The coating agent containing the prepared binder composition (A), inorganic particles (B), and functional composition (C) can be applied to the substrate film by the above-mentioned coating method, and is not particularly limited.

[0052] The drying and curing temperature after application is preferably 100°C or higher and lower than 200°C. At 100°C or higher, insufficient drying and curing can be prevented and blocking due to insufficient curing of the binder composition (A) can be prevented, so 100°C or higher is preferred. At temperatures lower than 200°C, the substrate film is less likely to shrink or deform due to heat and can be dried while maintaining its flatness, so less than 200°C is preferred. The drying and curing time is preferably 1 second or higher and lower than 180 seconds. At 1 second or longer, insufficient drying can be prevented and blocking due to insufficient curing of the binder composition (A) can be prevented, so 1 second or longer is preferred. From the standpoint of productivity, at temperatures lower than 180 seconds, costs can be reduced, so less than 180 seconds is preferred.

[0053] The thickness of the surface coating layer after drying and curing is preferably 5 to 35 μm. A thickness of 5 μm or more is preferable because it ensures the volume to absorb the ink after stamping. A thickness of 35 μm or less maintains the strength of the surface coating layer and prevents powder falling off, so a thickness of 35 μm or less is preferable.

[0054] The surface-treated plastic film of the present invention has a static friction coefficient (μs) of 0.65 or less, and more preferably 0.60 or less, when the surface coating layers are rubbed against each other. Within this range, friction is reduced when the film starts moving during operation or transportation, which is preferable as it suppresses the occurrence of toner transfer. Due to the nature of the friction coefficient, the dynamic friction coefficient is generally lower than the static friction coefficient. Due to this nature, if the static friction coefficient is below the above range, the dynamic friction coefficient will also be below the above range, and toner transfer will hardly occur during movement during operation or transportation. The static friction coefficient (μs) is preferably 0.1 or more, for example, 0.2 or more, which is preferable because within this range, toner transfer can be suppressed and problems such as winding slippage are less likely to occur when processed into a film roll.

[0055] The surface roughness (Ra) of the surface coating layer is greater than 1.6 μm and not greater than 4.0 μm. It is more preferably greater than 2.0 μm and not greater than 3.6 μm. By exceeding 1.6 μm, small irregularities are formed on the surface, and good resistance to imprint bleeding can be maintained even when the inorganic particle (B) ratio is within the range of the present invention, for example, even at a relatively low content of 20% by mass or 25% by mass. A surface roughness of 2.0 μm or greater is even more preferable, as it results in very good resistance to imprint bleeding. A surface roughness of 4.0 μm or less is preferable, as it does not deteriorate the transferability of the imprinting ink. A surface roughness of 3.6 μm or less is even more preferable, as it further improves the transferability of the imprinting ink and improves legibility. Furthermore, the present invention, by having such surface roughness, can contribute to distinguishability from other types of plastic cards by touch.

[0056] The maximum protrusion height (Rz) of the surface coating layer is greater than 20 μm and less than 40 μm. In one embodiment, the maximum protrusion height (Rz) of the surface coating layer is 21 μm or more and 38 μm or less, for example, 23 μm or more and 37 μm or less. Within the above range, the printing blur is improved, toner transfer can be suppressed, and toner fixation is also improved. Furthermore, by having such a maximum protrusion height, the present invention can contribute to the distinguishability from other types of plastic cards by feel.

[0057] The surface roughness (Ra) and maximum projection height (Rz) of the present invention are both values ​​measured in accordance with JIS B0601. μs can be controlled by the ratio of the binder composition to the inorganic particles, the ratio of the binder composition, the wax addition ratio, etc. Both Ra and Rz can be controlled by the type, average particle size, content, and type of binder composition of the inorganic particles used.

[0058] Thus, the present invention provides the above-mentioned effects of excellent toner fixation, suppression of toner transfer, and prevention of bleeding in stamping applications, by having the content of inorganic particles (B) of 20% by mass or more and 40% by mass or less relative to 100% by mass of the total solids content of the surface coating layer-forming composition, the static friction coefficient (μs) when the surface coating layers are rubbed together being 0.65 or less, the surface roughness (Ra) of the surface coating layers being more than 1.6 μm and 4.0 μm or less, and the maximum protrusion height (Rz) being more than 20 μm and 40 μm or less. Furthermore, because of these characteristics, the present invention can be distinguished from other types of plastic cards by touch. For example, even users with impaired vision, such as elderly people, can properly distinguish the surface-treated plastic film of the present invention by touch. On the other hand, as described above, the present invention can also reduce friction when the device starts moving during work or transportation, thereby suppressing the occurrence of toner transfer. In this way, the present invention can provide a good balance of toner fixability, tactile identifiability, and suppression of toner transfer by reducing friction.

[0059] The surface-treated plastic film of the present invention can be used for, for example, cards such as insurance cards, qualification certificates, drivers' licenses, student ID cards, patient registration cards, and business cards, labels for business use, delivery slips, and recording paper for printers. [Example]

[0060] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. First, the evaluation methods and measurement methods used in the present invention will be described.

[0061] (1) Static friction coefficient, dynamic friction coefficient (μs, μd) In accordance with JIS K7125:1999 "Test method for coefficient of friction of plastic films and sheets," measurements were taken using a Tensilon (A&D, RTG-1210) with two identical film test pieces prepared and their surface coating layers rubbed against each other under a load of 4.4 kg.

[0062] (2) Surface roughness (Ra), maximum protrusion height (Rz) Ra and Rz were measured using the formula in accordance with ISO 4287: 1997, and the arithmetic mean roughness and maximum protrusion height were measured, respectively. Measurements were made using a laser microscope VK-X100 (Keyence Corporation) within a 250 μm x 250 μm square, with the arithmetic mean roughness or maximum height defined as one point, and measurements were taken at four random points, with the average value being the surface roughness or maximum protrusion height (unit: μm).

[0063] (3) Dispersed particle size The dispersed particle size was measured as the 50% volume mean diameter (Dv50) using a laser diffraction particle size distribution analyzer SALD-7500nano (Shimadzu Corporation). The masterbatch was diluted with ion-exchange water to an absorbance of approximately 0.2, and measurements were performed using a high-concentration measurement unit. The refractive index of the inorganic particle with the highest mass percentage used was retrieved from the database built into the analyzer, and the particle size was calculated.

[0064] (4) Film Thickness The thickness of the base film was measured at 10 points using a contact film thickness meter manufactured by Ono Sokki Co., Ltd., and the arithmetic mean value was used as the film thickness. The thickness of the surface coating layer was measured at 10 points on the surface-treated plastic film after coating and drying using a contact film thickness meter to determine the arithmetic mean value, and the difference between this and the thickness of the base film measured in advance was used.

[0065] (5) Toner transferability (Toner transfer method A) An electrophotographic printer (Fuji Xerox Co., Ltd.: 495J Continuous Feed) was used to print on the surface coating layer, and then evaluation was carried out by toner transfer method A. In Toner Transfer Method A, two printed plastic films were cut to 9cm x 5cm, the printed surfaces were placed together, and the films were pinched at both ends with the fingers and bent up and down five times while still overlapping, and the degree of toner transfer to the opposing surface was visually determined. The criteria for toner transfer method B are as follows: ◎: No transfer at all ○: Slightly transferred in dots △: Transcribed, but the transcribed characters are unreadable ×: Transcribed and the transcribed characters can be read

[0066] (6) Toner transferability (Toner transfer method B) An electrophotographic printer (Fuji Xerox Co., Ltd.: 495J Continuous Feed) was used to print on the surface coating layer, and then evaluation was carried out by toner transfer method B. Toner Transfer Method B is a toner transfer evaluation method using the friction coefficient test method in accordance with JIS K7125:1999 "Test Method for the Coefficient of Friction of Plastic Films and Sheets." Two identical film test pieces were prepared using a Tensilon (A&D, RTG-1210). One of the test pieces was printed using the printer described above. The printed and unprinted surface coating layers were then placed together with the printed film test piece facing up, and measurements were performed under a load of 4.4 kg. The degree of toner transfer to the unprinted surface coating layer was visually evaluated. For visual evaluation, a mark was made at the position where the upper film was stationary before measurement; this position was designated the slippage position. The criteria for judgment are shown below. ◎: No transfer at all ○: Transferred only at the sliding start position, with slight spot-like transfer. No transfer occurred from other positions. △: Transferred only at the start of sliding, with slight linear transfer. No transfer occurred from other positions. ×: Slight linear transfer occurred at the sliding start position and other areas.

[0067] (7) Stamp bleeding A stamp was made on the surface coating layer using Shachihata Xstamper Name 9 (pigment ink: XLR-9N), and left to stand for 5 minutes, and the degree of bleeding of the letters was observed and judged according to the following criteria. ○: No bleeding occurs at all △: Blurring occurs, but the letters are legible ×: Difficulty in reading the characters

[0068] (8) Stamp rubbed off A stamp was made on the surface coating layer using Shachihata Xstamper Name 9 (pigment ink: XLR-9N) and left to stand for 30 seconds. The stamped area was then lightly rubbed with a Kimwipe, and the degree of rubbing of the letters was observed and evaluated according to the following criteria. ○: No rubbing occurs △: Scratches occur, but the letters are legible ×: Difficulty in reading the characters

[0069] (9) Powder shedding The powder shedding was evaluated using a powder shedding Gakushin friction tester (Yamaguchi Kagaku Sangyo Co., Ltd.) with a black backing (GA board-FS, Y-mesh, Takeo Co., Ltd.) at the contact point between the load head and the film, and the load on the head was set to 200 gf / 25 mm. 2 (5mm x 5mm) [0.0785MPa], and the film was rubbed against the load head in a reciprocating motion three times, after which the degree of whitening of the black backing paper was visually judged. 〇: The black backing paper was not whitened at all. △: Slight whitening is observed on the black backing ×: A lot of whitening is observed on the black backing

[0070] (10) Texture With the eyes closed, the surface coating layer was rubbed with the index finger, and the texture was evaluated using the following sensory evaluation criteria: Crisper (registered trademark) K2323: manufactured by Toyobo Co., Ltd., void-containing white polyester film, double-sided easy-adhesion treatment, apparent density 1.1 g / cm 3 , Ra=0.3 μm, Rz=7 μm (Ra, Rz, S of both surfaces are substantially the same). ◯: It has a rough texture and is different from Crisper (registered trademark) K2323. △: There is a slightly rough feel, and the difference from Crisper (registered trademark) K2323 is clear. ×: Indistinguishable from CRISPR (registered trademark) K2323.

[0071] (11) Toner Fixability Electrophotographic copying machine (Fuji Xerox: C3376, cardboard 2: 170-256 g / m 2 Toner was transferred and fixed onto the surface of the film's surface coating layer using a pressure sensitive adhesive tape (Nichiban Co., Ltd.: Cellotape (registered trademark), 25 mm wide) which was firmly attached to the toner fixing surface, and then slowly peeled off at an angle of 90° to the film surface, and the remaining toner on the film was visually evaluated according to the following criteria. ○: Toner remaining on the surface coating layer of the film is 90% or more by area. △: Toner remaining on the surface coating layer of the film is 70% or more and less than 90% by area ×: Toner remaining on the surface coating layer of the film is less than 70% by area

[0072] (Raw materials used) Binder composition (A) A-1: Polyester resin (Vylonal (registered trademark) MD1200, manufactured by Toyobo Co., Ltd., solid content 34% by mass) A-2: Melamine resin (Amidea (registered trademark) M-3, manufactured by DIC Corporation, solid content 80% by mass) A-3: Urethane resin (Elastron (registered trademark) H-3DF, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., solid content 27% by mass)

[0073] Inorganic particles (B) ·Inorganic particles B1 B-1: Calcium carbonate (Callite (registered trademark) KT, manufactured by Shiraishi Calcium Co., Ltd., average particle size 2.3 μm, solid content 100% by mass) B-2: Calcium carbonate (Callite (registered trademark) SA, manufactured by Shiraishi Calcium Co., Ltd., average particle size 3.3 μm, solid content 100% by mass) B-3: Calcium carbonate (Softon 2200, manufactured by Shiraishi Calcium Co., Ltd., average particle size 1.5 μm, solid content 100% by mass) B-4: Calcium carbonate (Brilliant (registered trademark)-15, manufactured by Shiraishi Calcium Co., Ltd., average particle size 0.15 μm, solid content 100% by mass) ·Inorganic particles B2 B-5: Silica (Sylysia 470, manufactured by Fuji Silysia Chemical Ltd., average particle size 14.0 μm, solid content 100% by mass) B-6: Silica (Sylysia 450, manufactured by Fuji Silysia Chemical Ltd., average particle size 8.0 μm, solid content 100% by mass) B-7: Silica (Sylysia 440, manufactured by Fuji Silysia Chemical Ltd., average particle size 6.2 μm, solid content 100% by mass)

[0074] Functional composition (C) C-1: Liquid wax (Hitec E-9015, manufactured by Toho Chemical Industry Co., Ltd., solid content 40% by mass) C-2: Granular wax (Chemipearl (registered trademark) W310, manufactured by Mitsui Chemicals, Inc., solid content 40% by mass) C-3: Antistatic agent (EL Polymer WS-52R, manufactured by Shin-Nakamura Chemical Co., Ltd., solid content 10% by mass) C-4: Dispersant (Poise 521, manufactured by Kao Corporation, solid content 40% by mass)

[0075] (Base film) Crisper® K2323: Toyobo Co., Ltd., white polyester film containing voids, double-sided easy-adhesion treatment, apparent density 1.1 g / cm 3 , Ra=0.3μm, Rz=7μm, S=2μm (Ra, Rz, S of both surfaces are practically the same)

[0076] Example 1 (Preparation of Coating Layer-Forming Composition 1) A coating layer-forming composition 1 having the following composition was prepared. (Coating layer-forming composition 1) Water 28.8 parts by mass Polyester resin A-1 46.6 parts by mass Calcium carbonate B-1 2.2 parts by mass Calcium carbonate B-5 4.1 parts by mass Liquid wax C-1 3.1 parts by mass Antistatic agent C-3 14.8 parts by mass Dispersant C-4 0.5 parts by mass

[0077] (Coating onto base film and drying) A 50 μm thick polyester synthetic paper, Crisper K2323, was used as the base film, and the coating layer forming composition 1 was applied to the easy-adhesion surface of K2323 so that the coating layer thickness after drying would be 10 μm.Then, it was dried at 180°C for 60 seconds to obtain the surface-treated plastic film described in Example 1.

[0078] (Examples 2 to 24, Comparative Examples 1 to 3) In Examples 2 to 24 and Comparative Examples 1 to 3, coating, drying and curing were carried out in the same manner as in Example 1, except that the surface coating layer-forming compositions shown in Tables 1, 2 and 3 were changed, to obtain surface-treated plastic films. In Tables 1, 2, and 3, the composition ratios of the binder composition A, inorganic particles B, and functional composition C of the surface coating layer-forming composition are shown in parts by mass of each solid content when the total solid content ratio is taken as 100. In actual surface coating layer-forming compositions, water is added so that the total solid content ratio of the liquid is 25%.

[0079] [Table 1]

[0080] [Table 2]

[0081] [Table 3]

[0082] Tables 4, 5 and 6 show the evaluation results of each example and comparative example.

[0083] [Table 4]

[0084] [Table 5]

[0085] [Table 6]

[0086] (Evaluation results) Examples 1 to 23 used binder composition (A) and inorganic particles (B), and satisfied the following ranges: the content of inorganic particles (B) was 20% by mass or more and 40% by mass or less, the static friction coefficient was 0.65 or less, Ra was more than 1.6 and 4.0 μm or less, and Rz was more than 20 μm and 40 μm or less, and the toner transferability, printability, powder shedding, feel, and toner fixability were excellent. On the other hand, Comparative Example 1 did not contain inorganic particles (B), and Ra and Rz were outside the above ranges, so bleeding and rubbing occurred in the printability to the extent that the characters were unreadable. Furthermore, when the feel was checked, it was indistinguishable from K2323. Comparative Example 2 had an inorganic particle content of 40% by mass or more and a static friction coefficient of 0.65 or more, so the characters were readable in toner transfer method A, and the transfer amount was particularly large in toner transfer method B. Furthermore, particle powdering was confirmed in the dusting properties. Comparative Example 3 had an Rz of less than 20.0 μm, so the printability was particularly poor due to rubbing, making the characters unreadable. Furthermore, the feel was also indistinguishable from K2323. [Industrial Applicability]

[0087] The surface plastic film of the present invention has good toner fixation properties, can be stamped, and does not cause toner transfer, so it can be suitably used for applications requiring toner printing, such as various labels, cards, delivery slips, and recording paper for printers.

Claims

1. A surface-treated plastic film having a surface coating layer formed on at least one surface of a base plastic film, the surface coating layer is a layer obtained by curing a surface coating layer-forming composition containing a binder composition (A) and inorganic particles (B), the binder composition (A) contains a polyester resin and a melamine compound, the content of the inorganic particles (B) in 100% by mass of the total solid content of the surface coating layer-forming composition is 20% by mass or more and 40% by mass or less, the static friction coefficient (μs) when the surface coating layers are rubbed against each other is 0.65 or less; The surface roughness (Ra) of the surface coating layer is greater than 1.6 μm and less than 4.0 μm, and the maximum projection height (Rz) is greater than 20 μm and less than 40 μm. Surface treated plastic film.

2. 2. The surface-treated plastic film according to claim 1, wherein the content of the polyester resin in 100% by weight of the total solid content of the binder composition (A) is 25% by weight or more and 100% by weight or less.

3. 2. The surface-treated plastic film according to claim 1, wherein the base plastic film is a white polyester film containing voids.

4. The surface-treated plastic film according to claim 1, wherein the base plastic film is a polyester film or a white polyester film containing voids, and the polyester resin is made from recycled raw materials such as film scraps and PET bottles in an amount of 25% by mass or more and 90% by mass or less relative to the total polyester resin constituting the polyester film or the white polyester film containing voids.

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