Modifier for polyester resin films, composition for polyester resin films, polyester resin film, and method for manufacturing laminated films.

Abstract

This invention provides a modifier for polyester resin films that can impart excellent electrostatic adhesion to polyester resin films, can be stably added to polyester resins, and offers improved workability. [Solution] The modifier for polyester resin films contains organic sulfonates. Assuming the total amount of organic sulfonates is 100% by mass, the content of organic sulfonates with particle sizes greater than 0 μm and less than or equal to 75 μm is 5% by mass or less, and the content of organic sulfonates with particle sizes greater than 75 μm and less than or equal to 150 μm is 5% by mass or more. Furthermore, it is preferable that the content of organic sulfonates with particle sizes greater than 1000 μm is 10% by mass or less.

Description

Technical Field

[0001] The present disclosure relates to a modifier for a polyester resin film, and a method for producing a composition for a polyester resin film, a polyester resin film, and a laminated film.

Background Art

[0002] Polyester resins are used in various applications such as fibers, casings, films, beverage bottles, and packaging containers. Among them, polyethylene terephthalate (PET) is mainly used for packaging containers and films. A polyester resin film is formed by solidifying a molten resin on a metal cooling roll. At this time, if the resin film does not adhere firmly to the cooling roll, wrinkles and thickness unevenness will occur in the formed resin film, resulting in poor appearance. Therefore, an electrostatic adhesion method is known in which an electric charge is applied to the cooling roll or the resin film by passing an electric current through the cooling roll or installing a pinning wire electrode, and the resin film is electrostatically adhered to the cooling roll.

[0003] However, in such an electrostatic adhesion method, if the rotation speed of the cooling roll is increased to increase the film formation speed, air is entrained between the cooling roll and the resin film, causing blister-like defects on the film surface. Therefore, there is a limit to increasing the film formation speed. Therefore, in order to enable further high-speed operation, for example, Patent Document 1 and Patent Document 2 disclose a technique of adding a sulfonate to polyester. As a result, the volume resistivity of the molten resin decreases, so that an electric charge can be efficiently applied to the molten resin immediately before reaching the cooling roll, and a significant improvement in the film formation speed has been achieved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] However, in the above technology, if the sulfonate is not added uniformly to the polyester resin, the electrostatic adhesion of the resin film to the cooling roll will not be stable, resulting in poor appearance. Furthermore, when adding powdered sulfonate to the polyester resin in order to uniformly add the sulfonate, depending on the particle size, sulfonate dust may be generated during the process, contaminating the work environment, or the fluidity of the sulfonate may decrease, making continuous supply unstable.

[0006] Therefore, the technology disclosed herein provides a modifier for polyester resin films that can impart excellent electrostatic adhesion to polyester resin films and improves the workability of adding it to polyester resins. The invention also provides a method for producing a polyester resin film composition, a polyester resin film, and a laminated film using the same. [Means for solving the problem]

[0007] This disclosure takes the following measures to solve the above-mentioned problems. [1] A modifier for polyester resin films containing an organic sulfonate, characterized in that, when the total amount of the organic sulfonate is 100% by mass, the content of the organic sulfonate with a particle size greater than 0 μm and less than or equal to 75 μm is 5% by mass or less, and the content of the organic sulfonate with a particle size greater than 75 μm and less than or equal to 150 μm is 5% by mass or more. [2] A modifier for polyester resin films according to [1], wherein, when the total amount of the organic sulfonate is 100% by mass, the content of the organic sulfonate with a particle size of more than 1000 μm is 10% by mass or less. [3] A modifier for polyester resin films according to [1] or [2], wherein the organic sulfonate is a compound represented by the following general formula (1). [ka] (In general formula (1), X is a residue obtained by removing 3 hydrogen atoms from benzene, and R 1 and R 2 (where M is a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and M is an alkali metal atom or a phosphonium compound.) [4] R of the general formula (1) 1 and R 2 A modifier for polyester resin films, wherein is a hydrogen atom and M is tetrabutylphosphonium [3]. [5] A method for producing a polyester resin film composition, characterized by mixing 0.01 to 12 parts by mass of any of the polyester resin film modifiers [1] to [4] with 100 parts by mass of polyester resin. A method for producing a polyester resin film, characterized by molding a molding composition containing a polyester resin film composition obtained by the manufacturing method of [6][5]. [7] A method for manufacturing a laminated film of two or more layers, characterized in that a polyester resin film obtained by the manufacturing method of [6] is laminated as at least one of the surface layers.

[0008] In this specification, the numerical range indicated by "A~B" includes both its upper and lower limits. In other words, "A~B" means "greater than or equal to A, and less than or equal to B." [Effects of the Invention]

[0009] This disclosure provides a modifier for polyester resin films that can impart excellent electrostatic adhesion to polyester resin films and improve the workability of adding it to polyester resins. Furthermore, it also provides a method for manufacturing a polyester resin film composition, a polyester resin film, and a laminated film using the modifier. [Modes for carrying out the invention]

[0010] Modifier for polyester resin films The modifier for polyester resin films (hereinafter also referred to as "modifier") is a powder or granular solid containing an organic sulfonate. By incorporating the modifier into a polyester resin film, excellent electrostatic adhesion can be imparted to the film.

[0011] <Organic sulfonates> Any organic sulfonate compound that can improve the electrostatic adhesion of polyester resin films is acceptable, and it may be used alone or in combination of two or more. However, the organic sulfonate must maintain the particle size ratio described later until the time of addition to the polyester resin.

[0012] As an organic sulfonate, for example, a compound represented by the following general formula (1) is preferred. [ka] (In general formula (1), X is a residue obtained by removing 3 hydrogen atoms from benzene, and R 1 and R 2 (where M is a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and M is an alkali metal atom or a phosphonium compound.) Compounds represented by general formula (1) include sodium 3,5-dicarboxybenzenesulfonate, tetrabutylphosphonium 3,5-dicarboxybenzenesulfonate, sodium 3,5-bis(methoxycarbonyl)benzenesulfonate, tetrabutylphosphonium 3,5-bis(ethoxycarbonyl)benzenesulfonate, sodium 3,5-bis(propoxycarbonyl)benzenesulfonate, tetrabutylphosphonium 3,5-bis(butoxycarbonyl)benzenesulfonate, tetrabutylphosphonium 3,5-bis(pentyloxycarbonyl)benzenesulfonate, and sodium 3,5-bis(hexyloxycarbonyl)benzenesulfonate. Among these, organic sulfonates are represented by R in general formula (1). 1 and R 2Particularly preferred is tetrabutylphosphonium 3,5-dicarboxybenzenesulfonate, wherein R is a hydrogen atom and M is a phosphonium compound.

[0013] <Particle size of organic sulfonate> When the total amount of the organic sulfonate contained in the modifier is 100% by mass, the content ratio of the organic sulfonate having a particle size of more than 0 μm and 75 μm or less is 5% by mass or less, preferably 2% by mass or less. By adjusting the content of the particles having a particle size of more than 0 μm and 75 μm or less within this range, dust generated during the addition of the modifier to the polyester resin can be effectively suppressed, and contamination of the working environment can be reduced.

[0014] Also, when the total amount of the organic sulfonate contained in the modifier is 100% by mass, the content ratio of the organic sulfonate having a particle size of more than 75 μm and 150 μm or less is 5% by mass or more. By adjusting the content of the particles having a particle size of more than 75 μm and 150 μm or less within this range, the fluidity of the organic sulfonate is maintained at a desired level, and continuous supply of the modifier using a feeder or the like can be stably performed. Thus, by adjusting the content ratios of the particles having a particle size of more than 0 μm and 75 μm or less and the particles having a particle size of more than 75 μm and 150 μm or less of the organic sulfonate within a predetermined range, the workability when adding the modifier to the polyester resin can be improved.

[0015] Furthermore, when the total amount of the organic sulfonate contained in the modifier is 100% by mass, the content ratio of the organic sulfonate having a particle size of more than 1000 μm is preferably 10% by mass or less, more preferably 3% by mass or less. By adjusting the content of the particles having a particle size of more than 1000 μm within this range, the flow of the modifier from a feeder or the like becomes uniform, and the supply of the modifier to the polyester resin can be further stabilized. The particle size of the organic sulfonate can be measured using a particle size distribution measuring device using the laser diffraction / scattering method or a test sieve of JIS Z 8801-1:2019.

[0016] <Ethanol-insoluble content> The modifier may contain impurities generated during the synthesis of organic sulfonates. For example, if the modifier contains ethanol-insoluble matter, it is preferable that the amount of ethanol-insoluble matter in the modifier be 100 μg / g or less, and more preferably 50 μg / g or less. By adjusting the amount of ethanol-insoluble matter to this range, it is possible to suppress appearance defects such as a decrease in the transparency of the polyester resin film and the formation of spots in the film (visible foreign matter contamination) caused by the ethanol-insoluble matter. The amount of ethanol-insoluble matter can be measured, for example, according to the soap test method of JIS K3304:2019.

[0017] <Iron element> Similarly, the iron content in the modifier is preferably 50 ppm or less, and more preferably 10 ppm or less. By adjusting the iron content to the above range, it is possible to prevent the modifier from being colored with an iron-derived color, such as red.

[0018] Compositions for polyester resin films Next, compositions for polyester resin films will be described. These compositions contain a polyester resin and a modifier, and include a masterbatch containing a high concentration of the modifier, as well as intermediate products in the manufacturing process of the polyester resin film described later. Note that the organic sulfonate in the modifier dissolves in the polyester resin during melt-kneading. Therefore, in the compositions for polyester resin films and the polyester resin films described later, the particle size and content ratio of the organic sulfonate are not maintained within the above-mentioned range.

[0019] <Polyester resin> As the polyester resin, any known resin having a polycondensate of a polycarboxylic acid and a polyhydric alcohol as its basic structure can be used. There are no particular restrictions on the polycarboxylic acid, and examples include aliphatic or alicyclic dicarboxylic acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dimer acid, dodecanedioic acid, and 1,6-cyclohexanedicarboxylic acid, as well as aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and diphenyldicarboxylic acid. One or more of these polycarboxylic acids can be used. On the other hand, there are no particular restrictions on the polyhydric alcohols, and examples include 1,2-ethanediol, 2,2'-oxydiethanol, 2,2'-(ethylenedioxy)diethanol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, aliphatic or alicyclic diol units such as isosorbide, xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4'-hydroxyphenyl)propane, 2,2-bis(4'-β-hydroxyethoxyphenyl)propane, bis(4-hydroxyphenyl)sulfone, bis(4-β-hydroxyethoxyphenyl)sulfone, etc. One or more of these polyhydric alcohols can be used. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polylactic acid, polyhydroxybutyric acid, polyethylene naphthalate, polyarylate, acid-modified polyester copolymerized with isophthalic acid, and glycol-modified polyester (PET-G) copolymerized with 1,4-cyclohexanedimethanol. Furthermore, polyester resins may be used individually or in combination of two or more types.

[0020] The polyester resin film composition may further contain additives as needed. Examples of additives include antioxidants, antistatic agents, ultraviolet absorbers, infrared absorbers, antiblocking agents, color inhibitors, deodorizers, antioxidants, crystal nucleating agents, heat stabilizers, flame retardants, and lubricants. Additives may be used individually or in combination of two or more.

[0021] The content of the modifier in the polyester resin film composition is not particularly limited and can be appropriately set depending on the type of polyester resin film composition and the type of modifier. For example, if the polyester resin film composition is a masterbatch, it is preferable that the modifier be in the amount of 0.1 to 12 parts by mass per 100 parts by mass of polyester resin. On the other hand, if the polyester resin film composition is an intermediate product in the resin film manufacturing process, the content of the modifier can be arbitrarily changed depending on the manufacturing process. However, the polyester resin film composition immediately before being formed into a film preferably contains 0.01 to 10 parts by mass of modifier per 100 parts by mass of polyester resin, and more preferably contains 0.01 to 1 part by mass.

[0022] <Polyester resin film> Next, polyester resin films will be described. Polyester resin films are made by molding a molding composition containing polyester resin and a modifier into a film. By containing organic sulfonates, polyester resin films can exhibit excellent electrostatic adhesion.

[0023] The polyester resin film preferably contains 0.01 to 10 parts by mass of a modifier per 100 parts by mass of polyester resin, and more preferably 0.01 to 1 part by mass. The film thickness of the polyester resin film is not particularly limited, but is preferably 10 to 300 μm.

[0024] <Laminated film> The laminated film is a laminated film consisting of two or more layers, with the above-mentioned polyester resin film as at least one of the surface layers. The other layers of the laminated film are formed from thermoplastic resin, adhesive, anchor coating agent, adhesive resin, etc. Examples of thermoplastic resins include polyolefin resins, polyester such as polyethylene terephthalate, polyamide such as nylon 6, polyvinyl alcohol, polystyrene, and acrylic resins such as polymethyl methacrylate. The same polyester resin as the material contained in the polyester resin film can also be used as the thermoplastic resin. The thermoplastic resin may also contain additives for a specific purpose. Examples of additives include ultraviolet absorbers, infrared absorbers, antiblocking agents, antistatic agents, antifogging agents, heat stabilizers, neutralizing agents, plasticizers, lubricants, flame retardants, and crystal nucleating agents.

[0025] The total film thickness of the laminated film is not particularly limited, but is preferably 10 to 300 μm. In addition, the ratio of the film thickness of the polyester resin film layer laminated on one side to the film thickness of the other layers can be set as appropriate, but is preferably 5:90 to 20:60.

[0026] ≪Manufacturing method≫ Next, we will describe a composition for polyester resin films, a polyester resin film, and a method for manufacturing a laminated film.

[0027] <Method for producing a composition for polyester resin film> There are two main methods for producing compositions for polyester resin films. The first method involves preparing a masterbatch containing a polyester resin and a high-concentration modifier in advance, and then mixing this masterbatch with the polyester resin to produce a molding composition. In this specification, "molding composition" refers to a composition containing a polyester resin film composition that is used in the film molding process.

[0028] The production of masterbatches can be carried out using conventionally known methods and is not particularly limited. Examples of masterbatch production methods include a method in which a polyester resin is brought to a molten state using an extruder such as a single-screw or multi-screw extruder, a modifier is added to the extruder via a side feed, etc., and granulation occurs while melting and kneading. Another method involves pre-mixing the polyester resin and modifier in a mixer such as a tumbler blender, super mixer, or Henschel mixer, adding the mixture to an extruder such as a single-screw or multi-screw extruder using a feeder, etc., and granulating the masterbatch while melting and kneading the mixture in the extruder. Furthermore, it is also possible to add the polyester resin to an extruder such as a single-screw or multi-screw extruder using a main feeder, etc., add the modifier to the extruder via a sub-feeder, etc., and granulate the masterbatch while melting and kneading.

[0029] The production of molding compositions using masterbatches can also be carried out using conventionally known methods and is not particularly limited. For example, in the masterbatch production method described above, a molding composition can be produced by using a masterbatch instead of a modifier and by omitting the granulation step.

[0030] The second method involves directly producing a molding composition containing a polyester resin film composition by mixing a polyester resin with a modifier. This second method is also not particularly limited and can utilize conventionally known methods. An example of this second method is the masterbatch manufacturing method described above, but without the granulation step.

[0031] In a method for producing a polyester resin film composition, the mixing ratio of the modifier to the polyester resin can be appropriately set depending on the type of polyester resin film composition and the type of modifier. For example, it is preferable to mix 0.01 to 12 parts by mass of the modifier with 100 parts by mass of the polyester resin. Specifically, when producing a masterbatch, it is preferable to mix 0.1 to 12 parts by mass of the modifier with 100 parts by mass of the polyester resin. On the other hand, when directly producing a molding composition containing a polyester resin film composition, it is preferable to mix 0.01 to 10 parts by mass of the modifier with 100 parts by mass of the polyester resin, and more preferably 0.01 to 1 part by mass.

[0032] <Method for manufacturing polyester resin film> Polyester resin films are manufactured by forming a film from a molten molding composition using known film-forming methods. Examples of film-forming methods include inflation molding such as air-cooled inflation molding, air-cooled two-stage inflation molding, air-cooled three-stage inflation molding, and water-cooled inflation molding, as well as T-die molding using straight manifold type, coat hanger type, or combinations thereof as T-dies. The film may also be stretched, and examples of stretching methods include simultaneous biaxial stretching with a tenter, sequential biaxial stretching with a roll and tenter, and biaxial stretching by inflation.

[0033] <Method for manufacturing laminated film> Laminated films are manufactured by laminating a polyester resin film as the surface layer of at least one of two or more laminated films using known film-forming methods. Examples of film-forming methods include dry lamination, sand lamination, extrusion lamination, and co-extrusion. When manufacturing laminated films using dry lamination, sand lamination, or extrusion lamination, known polyurethane adhesives, organic titanium anchor coating agents, isocyanate anchor coating agents, and adhesive resins can be used. In co-extrusion manufacturing, inflation molding and T-die molding can be used, and either unstretched or stretched molding methods can be used. [Examples]

[0034] The configuration and effects of this disclosure will be described in more detail below based on the examples. In the following examples and comparative examples, "parts" means parts by mass.

[0035] Preparation Example 1 Tetrabutylphosphonium salt of 3,5-dicarboxybenzenesulfonate (A-1), an organic sulfonate, was separated into four types using a JIS test sieve: greater than 0 μm and less than or equal to 75 μm, greater than 75 μm and less than or equal to 150 μm, greater than 150 μm and less than or equal to 1000 μm, and greater than 1000 μm. These were then mixed by dry blending in the proportions (mass%) shown in Table 1 below to prepare a modifier for polyester resin films (K-1).

[0036] Preparation Examples 2-10 The modifiers for polyester resin films (K-2 to K-6, k-1 to k-4) were prepared in the same manner as in Preparation Example 1, except that the types of organic sulfonates and the proportions of each particle size were changed as shown in Table 1 below.

[0037] [Table 1] Organic sulfonates and control substances listed in Table 1 A-1: 3,5-Dicarboxybenzenesulfonate tetrabutylphosphonium salt A-2: 3,5-Dicarboxybenzenesulfonate sodium salt A-3: 3,5-Bis(methoxycarbonyl)benzenesulfonate sodium salt a-1: Diglycerin monostearate

[0038] Example 1-1 95 parts of polyethylene terephthalate (product name "RAMAPET N-1", manufactured by Indorama Ventures Public Company Limited) as a polyester resin and 5 parts of the modifier (K-1) obtained in Preparation Example 1 were supplied to a coaxial twin-screw compounding extruder using a feeder, melt-kneaded at 250-290°C, extruded from a strand die, and rapidly cooled with water to obtain strands. These strands were cut with a pelletizer to prepare a masterbatch (N-1), which is a composition for polyester resin films.

[0039] Examples 1-2 to 1-6, Comparative Examples 1-1 to 1-4 Masterbatches (N-2 to N-6, n-1 to n-4) were prepared in the same manner as in Example 1-1, except that the type and proportion of the modifier were changed as shown in Table 2 below.

[0040] [Table 2]

[0041] <Evaluating Masterbatch (MB) Productivity> The productivity of preparing the masterbatch was evaluated based on the following criteria. The evaluation results are shown in Table 2. [Evaluation Criteria] 3. Organic sulfonates could be supplied stably, there was no contamination of the equipment, and stable production was possible 24 hours a day. 2. Organic sulfonates could be supplied stably, there was no contamination of the equipment, and stable production was possible for 8 hours. 1: Organic sulfonates could not be supplied stably and / or the equipment was contaminated, making stable production impossible for 8 hours.

[0042] Example 2-1 99.5 parts of polyethylene terephthalate (product name "RAMAPET N-1") and 0.5 parts of masterbatch (N-1) were supplied to a coaxial twin-screw compounding extruder using a feeder and melt-mixed at 260-280°C. Next, using a multi-manifold T-die, the amount of molten resin supplied and the screw rotation speed were adjusted, and the mixture was wound onto a cooling roll heated to 30°C to obtain an unstretched film. The obtained unstretched film was stretched three times in length and four times in width at 110°C, then heat-treated at 235°C, and slowly cooled to room temperature to obtain a polyester resin film (F-1) with a thickness of 60 μm.

[0043] Examples 2-2 to 2-6, Comparative Examples 2-1 to 2-4 Polyester resin films (F-2 to F-6, f-1 to f-4) were obtained in the same manner as in Example 2-1, except that the type and blending ratio of the masterbatch, as well as whether or not the polyester resin film underwent biaxial stretching and its film thickness, were changed as shown in Table 3 below. In the case where biaxial stretching was not performed, the process was carried out up to the step of obtaining the unstretched film in Example 2-1.

[0044] [Table 3]

[0045] <Evaluation of electrostatic adhesion> In the manufacturing of polyester resin films, a molten mixture of masterbatch and polyester resin was extruded into a film and cast onto a cooling roll. A pinning wire (voltage 10KV) was applied to the top of the extruded film to ensure close contact with the cooling roll. The electrostatic adhesion was evaluated based on the following criteria. The evaluation results are shown in Table 3. [Evaluation Criteria] 3. Film formation can be performed stably at a cooling roll speed of 80 m / min or more. 2: Stable film formation is possible at a cooling roll speed of 50 m / min or more and less than 80 m / min. 1: Stable film formation is only possible at cooling roll speeds of less than 50 m / min.

[0046] Example 3-1 99.5 parts of polyethylene terephthalate (product name "RAMAPET N-1") as a polyester resin and 0.5 parts of masterbatch (N-1) were supplied to the first coaxial twin-screw compounding extruder using a feeder and melt-kneaded at 260-280°C. Meanwhile, only polyethylene terephthalate (product name "RAMAPET N-1") as a polyester resin was supplied to the second coaxial twin-screw compounding extruder and melt-kneaded at 260-280°C. Next, using a multi-manifold T-die, the amount of molten resin supplied and the screw rotation speed were adjusted, and the molten resin layers from the first coaxial twin-screw compounding extruder were co-extruded so that the layers from the second coaxial twin-screw compounding extruder became the surface layers and the layers from the second coaxial twin-screw compounding extruder became the intermediate layer. The film was then wound onto a cooling roll heated to 30°C to obtain a laminated unstretched film in which the thickness ratio of layer A (one surface layer), layer B (intermediate layer), and layer A (the other surface layer) was 10:80:10. The obtained laminated unstretched film was stretched to 3 times its length and 4 times its width at 110°C, then heat-treated at 235°C, and slowly cooled to room temperature to obtain a laminated film with a thickness of 60 μm.

[0047] Examples 3-2 to 3-7, Comparative Examples 3-1 to 3-4 Each laminated film was obtained in the same manner as in Example 3-1, except that the type and blending ratio of the masterbatch in layers A and B, whether or not the laminated film was biaxially stretched, the total film thickness, and the ratio of layers A to B were changed as shown in Table 4 below. For each laminated film, layer A used the same raw materials and component composition as the corresponding polyester resin film in Table 3. If biaxial stretching was not performed, the process was carried out up to the step of obtaining the unstretched laminated film in Example 3-1.

[0048] [Table 4]

[0049] <Evaluation of electrostatic adhesion of laminated films> In the manufacturing of laminated films, two types of molten resin were co-extruded into a laminated film and cast onto a cooling roll. A pinning wire (voltage 10KV) was applied to the top of the extruded film to ensure close contact with the cooling roll. The electrostatic adhesion was evaluated based on the following criteria. The evaluation results are shown in Table 4. [Evaluation Criteria] 3. Film formation can be performed stably at a cooling roll speed of 80 m / min or more. 2: Stable film formation is possible at a cooling roll speed of 50 m / min or more and less than 80 m / min. 1: Stable film formation is only possible at cooling roll speeds of less than 50 m / min.

[0050] In Examples 1-1 to 1-6, the process of adding the modifier to the polyester resin during masterbatch production was smooth, resulting in good masterbatch productivity. Furthermore, the polyester resin films of Examples 2-1 to 2-6 and the laminated films of Examples 3-1 to 2-6, produced using the masterbatches of Examples 1-1 to 1-6, exhibited excellent electrostatic adhesion. On the other hand, in Comparative Example 1-1, the proportion of organic sulfonates with a particle size greater than 0 μm and less than or equal to 75 μm in the modifier was too high, resulting in poor workability in adding the modifier to the polyester resin and poor masterbatch productivity. In Comparative Examples 1-2 and 1-4, the proportion of organic sulfonates with a particle size greater than 75 μm and less than or equal to 150 μm in the modifier was too low, resulting in unstable addition of the modifier to the polyester resin and poor masterbatch productivity. However, the polyester resin films of Comparative Examples 2-1, 2-2, and 2-4, and the laminated films of Comparative Examples 3-1, 3-2, and 3-4, produced using the masterbatches obtained in Comparative Examples 1-1, 1-2, and 1-4, showed good electrostatic adhesion. In Comparative Example 1-3, the productivity of the masterbatch was good. However, because the modifier contained diglycerin monostearate instead of an organic sulfonate, the polyester resin film of Comparative Example 2-3 and the laminated film of Comparative Example 3-3, produced using the masterbatch obtained in Comparative Example 1-3, had poor electrostatic adhesion.

Claims

1. A modifier for polyester resin films containing an organic sulfonate, A modifier for polyester resin films, characterized in that, when the total amount of the organic sulfonate is 100% by mass, the content of the organic sulfonate with a particle size greater than 0 μm and less than or equal to 75 μm is 5% by mass or less, and the content of the organic sulfonate with a particle size greater than 75 μm and less than or equal to 150 μm is 5% by mass or more.

2. The modifier for polyester resin films according to claim 1, wherein, when the total amount of the organic sulfonate is 100% by mass, the content of the organic sulfonate with a particle size exceeding 1000 μm is 10% by mass or less.

3. The modifier for polyester resin films according to claim 1 or 2, wherein the organic sulfonate is a compound represented by general formula (1). 【Chemistry 1】 (In general formula (1), X is a residue obtained by removing three hydrogen atoms from benzene, and R １ and R ２ (where M is a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and M is an alkali metal atom or a phosphonium compound.)

4. R in the general formula (1) １ and R ２ The modifier for polyester resin films according to claim 3, wherein is a hydrogen atom and M is tetrabutylphosphonium.

5. A method for producing a polyester resin film composition, characterized by mixing 0.01 to 12 parts by mass of the polyester resin film modifier described in claim 1 or 2 with 100 parts by mass of polyester resin.

6. A method for producing a polyester resin film, characterized by molding a molding composition containing a polyester resin film composition obtained by the manufacturing method described in claim 5.

7. A method for manufacturing a laminated film with two or more layers, A method for manufacturing a laminated film, characterized by laminating a polyester resin film obtained by the manufacturing method described in claim 6 as at least one of the surface layers.

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