JP2022142712A - Easy adhesive polyester film for in-mold label - Google Patents

Abstract

To provide an easy adhesive polyester film for an in-mold label that has an easy adhesive layer having excellent adhesion to various inks used in printing. etc., like an ultraviolet (UV) hardening type ink and an aqueous flexographic ink, and an in-mold vessel made of thermoplastic resin such as polyester.SOLUTION: An easy adhesive polyester film for an in-mold label has an easy adhesive layer on at least one surface of a polyester film, in which the easy adhesive layer is made of a hardened composition including an ion conduction type anti-static agent, a polyester resin, and a polycarbonate-urethane resin, and the surface of the easy adhesive layer has characteristics such as a specific surface specific resistance value.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a polyester film excellent in mass productivity, easy adhesion and antistatic properties. The present invention relates to an easy-adhesive polyester film for in-mold labels, which is excellent in adhesion and suitable as an information recording material or a printing material.

Biaxially oriented polyester film has excellent properties such as mechanical properties, electrical properties, and dimensional stability. It is used as a base film in many printing fields such as printing materials and photographic materials.
Especially when it is used as a label, the surface opposite to the easy-adhesion layer may be subjected to inorganic vapor deposition in order to increase concealability, or may be subjected to adhesive processing for attachment to a container, etc., or a release agent such as silicone. It can also be used as a release liner (separator) by applying

In recent years, an in-mold molding method has been known as a method of integrally molding synthetic resin molding containers and the like. Polyethylene and polypropylene resins are well-known synthetic resins, but polyester-based resin moldings have also been proposed from an environmental point of view. (PETG) copolyesters containing 1,4-cyclohexanedimethanol as a copolymerization component are generally well known.

Various labels using a polyester film for use in in-mold molding using such a polyester resin have been proposed so far. The lamination method increases the environmental load and production cost due to the increase in processing steps.

In addition, polyester film has high insulating properties in these applications, and often causes problems during printing, such as ink loss due to dust adsorption due to static electricity during various processes, and poor cleaning due to adhesion of films due to triboelectrification. There is

Therefore, as one method for imparting easy-adhesion antistatic properties to the surface of a polyester film, a method is known in which various resins are applied to the surface of the polyester film to form a coating layer having easy-adhesion properties and antistatic properties. there is

Various conventional ink-adhesive type polyester-based coating films are often provided with a coating layer made of a specific resin on the surface of the substrate polyester film (see, for example, Patent Document 1). Examples of resins constituting the coating layer include polyester resins, polyurethane resins, acrylic resins, etc., which are used singly or in combination of two or more; A mixed one and the like are included.

In addition, as a means for obtaining antistatic performance, even in a uniaxially stretched polyester-based laminated film, it can be obtained by mixing a polymer antistatic agent and an additive (see Patent Documents 2 and 3). .

In order to impart an antistatic function, an antistatic agent having a polar group is used. Among them, it is known that cationic antistatic agents and anionic antistatic agents are used for the effect of lowering the surface specific resistance value due to their high polarity among ion-conducting antistatic agents. However, when an antistatic agent with a high polar group and high hydrophilicity is used, when mixed with the above polyester resin or polyurethane resin, the polar species difference (functional group) causes gelation due to ion adsorption (interaction). There is also a problem that it can not be applied to the coating liquid.

Furthermore, in such prior art, especially in the case of film roll state in summer, cut sheet storage, land transportation, marine transportation, etc., the film surface and its coating layer are covered by indoor temperature and humidity under high temperature and high humidity. There was a case where the component that was absorbed was transferred to the back surface. This is because migration to the back surface is unlikely to occur under normal temperature and humidity environments, but when the moisture content in the atmosphere increases beyond a certain temperature and humidity range, the components of the coating soften and migrate to the back surface. This phenomenon lowers the function of the coating layer, and in particular, when the antistatic agent component migrates to the back surface, there is a risk of causing whitening stains on the mold adhesion surface during in-mold molding processing. Conventionally, it has been very difficult for an easy-adhesive layer having adhesion and antistatic functions for printing ink or the like to suppress migration to the back surface of a polyester film. In order to avoid this, it is effective to reduce the pressure of the winding roll and control the temperature and humidity during storage, but it is not possible to completely avoid it, and there is a problem that it leads to deterioration of productivity.

A certain temperature and humidity range, for example, the temperature and humidity data inside a container that is transported by sea in summer, is disclosed by the transportation industry. Although the inside of the container is sealed, the temperature rises to about 40°C at maximum. Furthermore, with respect to humidity, the maximum humidity rises to 80% due to the evaporation of moisture contained in the corrugated paper used for packing materials. Therefore, in order to provide an easy-adhesive polyester film that does not easily change in quality even in a harsh environment, it is necessary to evaluate under the conditions of 50 ° C. It is desirable to prevent the components in the coating layer from migrating to other articles in contact or to the back of the film itself.

JP-A-11-105221 Japanese Patent Application Laid-Open No. 2008-296447 JP 2010-208059 A

The present invention has been made against the background of such problems of the prior art. That is, the object of the present invention is to provide excellent antistatic properties on the surface of the easy-adhesion layer so that the antistatic agent in the easy-adhesion layer can be applied to other films, separator papers, pressure-sensitive adhesive surfaces, molds, or easy-to-adhesion layers that come into contact with the easy-adhesion layer. Various inks such as ultraviolet (UV) curable inks and water-based flexographic inks used in printing, etc., and thermoplastic resin in-molds such as polyester, suppressing migration to the back surface (back surface) of the adhesive polyester film itself. An object of the present invention is to provide an easily adhesive polyester film for an in-mold label, which has an easily adhesive layer excellent in adhesion to a molded container.

That is, the present invention consists of the following configurations.
1. Having an easy-adhesion layer on at least one surface of the polyester film,
The easy adhesion layer is formed by curing a composition containing an ion-conducting antistatic agent, a polyester resin, and a polycarbonate urethane resin, and the surface specific resistance of the easy adhesion layer surface is 1.0×10 ¹³ Ω/sq or less. And, after contacting another polyester film to the surface of the easy adhesion layer and holding it at 50 ° C. under a pressure of 1 kg / cm ² for 3 days, the other polyester film that was in contact with the surface of the easy adhesion layer An easy-adhesive polyester film for an in-mold label, the surface of which has a surface specific resistance of 1.0×10 ¹⁴ Ω/sq or more.
2. Another polyester film is brought into contact with the surface of the easy-adhesion layer, and the surface resistivity of the easy-adhesion layer surface is 1.0 after holding for 3 days at 60° C. and 90% temperature and humidity under a pressure of 1 kg/cm ² . x 10 ¹³ Ω/sq or less, and another polyester film is brought into contact with the surface of the easy-adhesion layer, and the easy-adhesion layer is held at 60°C and 90% temperature and humidity under a pressure of 1 kg/cm ² for 2 days. 1. The easy-adhesive polyester film for in-mold labels as described in 1 above, wherein the other polyester film in contact with the surface has a surface specific resistance of 1.0×10 ¹³ Ω/sq or more.
3. The in-mold label facilitator according to the first or second above, wherein the solid content of the ion-conducting antistatic agent is 1 to 8% by mass when the total solid content contained in the composition is 100% by mass. Adhesive polyester film.
4. The easy-adhesive polyester for in-mold labels according to any one of the first to third above, which contains 0 to 50% by mass of a crosslinking agent as a solid content when the total solid content contained in the composition is 100% by mass. the film.
5. 4. The easy-adhesive polyester film for in-mold labels according to any one of the first to fourth items, wherein the easy-adhesion layer is heat-sealed and adhered to a blow-molded container containing a thermoplastic resin.

The easy-adhesive polyester film for in-mold labels of the present invention has excellent antistatic properties, suppresses the migration of the antistatic agent contained in the easy-adhesion layer to other articles or the back surface even under high temperature and high humidity, and Excellent adhesion with various inks such as curable inks and water-based flexographic inks, and with in-mold molded containers made of thermoplastic resin such as polyester.

(Polyester film substrate)
The polyester resin constituting the polyester film substrate in the present invention includes polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polytrimethylene terephthalate and the like, as well as the diol component or dicarboxylic acid component of the polyester resin as described above. is a copolymerized polyester resin in which a part of is replaced with the following copolymerization components, for example, as copolymerization components, diol components such as diethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, polyalkylene glycol , adipic acid, sebacic acid, phthalic acid, isophthalic acid, 5-sodium isophthalic acid, and dicarboxylic acid components such as 2,6-naphthalenedicarboxylic acid.

The polyester resin preferably used for the polyester film substrate in the present invention is mainly selected from polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate and polyethylene-2,6-naphthalate. Among these polyester resins, polyethylene terephthalate is most preferable from the viewpoint of balance between physical properties and cost. In addition, the polyester film substrate composed of these polyester resins is preferably a biaxially oriented polyester film, which can improve chemical resistance, heat resistance, mechanical strength, and the like.

The catalyst for polycondensation used in the production of the polyester resin is not particularly limited, but antimony trioxide is suitable because it is inexpensive and has excellent catalytic activity. It is also preferable to use a germanium compound or a titanium compound. Further preferred polycondensation catalysts include catalysts containing aluminum and/or compounds thereof and phenolic compounds, catalysts containing aluminum and/or compounds thereof and phosphorus compounds, and catalysts containing aluminum salts of phosphorus compounds.

Polyethylene resins, polypropylene resins, and polyester resins are used as the main raw materials for manufacturing synthetic paper. In particular, polyester resins, typified by polyethylene terephthalate, have excellent mechanical properties. , thermal properties, etc., it has been deployed in a wide range of applications.

Methods of obtaining a film with functions similar to paper generally include a method of containing a large amount of fine cavities inside the film, and surface treatments such as sandblasting, chemical etching, and matting on a flat film. A method of roughening the surface by performing Among these methods, the former method, which contains a large amount of fine cavities inside the film, not only provides paper-like hiding power and whiteness, but also reduces the weight of the film itself, thereby reducing the cost per unit area. It is widely used due to its merits, such as the fact that it can be suppressed, and that it provides appropriate flexibility and cushioning properties, resulting in excellent image clarity during printing.

As a method for expressing fine voids inside the film, in general, an incompatible thermoplastic resin (hereinafter referred to as an incompatible resin) is mixed in a polyester resin, and the incompatible resin is added to the polyester resin. A method of forming voids by interfacial peeling between the polyester-based resin and the incompatible resin by obtaining a sheet in which the resin is dispersed and stretching the sheet in at least one axial direction can be exemplified. Polyolefin-based resins such as polyethylene-based resins, polypropylene-based resins, and polymethylpentene-based resins, and polystyrene-based resins are preferably used as incompatible resins for creating cavities in polyester-based resins.

The polyester film substrate in the present invention is particularly preferably a biaxially oriented polyester film from the viewpoint of practicality such as strength, stiffness and dimensional stability.

The layer structure of the polyester film substrate may be a single layer structure or a laminated structure, but it is a laminated structure of A layer / B layer / A layer, the A layer contains inorganic particles, and the B layer contains fine cavities. It is a preferred form to have a laminated structure that By arranging a layer containing inorganic particles on the surface layer A, it is possible to improve the slipperiness of the film, that is, the handling property and hiding property, and the microcavities are contained only in the inner layer B layer. As a result, a preferable white appearance can be obtained, and the strength of the film surface can be ensured while exhibiting the cushioning properties of the film. Although the method for forming the laminated structure is not particularly limited, co-extrusion is preferable from the viewpoint of stability during production and processing costs.

Further, the polyester film substrate in the present invention may have a single layer structure or a multilayer structure, but it is preferable that some or all of the layers are opaque. The optical density indicating the opacity of the white void-containing polyester film is preferably 0.3 or more, more preferably 0.3 to 4.0, and particularly preferably 0.5 to 3.0. . When the optical density is 0.3 or more, when printing is applied to the easy-adhesion layer surface of the white void-containing polyester film, the printing effect becomes clear, which is preferable. Moreover, when the optical density is 4.0 or less, a more excellent printing effect can be expected, which is preferable.

Although the method for obtaining the optical density within the above range is not particularly limited, it can be achieved by incorporating inorganic particles or a thermoplastic resin incompatible with the polyester resin into the polyester resin. The content of these is not particularly limited, but in the case of inorganic particles, it is preferably 5 to 35% by mass, particularly preferably 8 to 25% by mass, based on the polyester produced. On the other hand, when an incompatible thermoplastic resin is contained, it is preferably 5 to 35% by mass, particularly preferably 8 to 28% by mass, based on the polyester. In addition, when inorganic particles and a thermoplastic resin incompatible with a polyester resin are used in combination, the total amount is 40% by mass or less with respect to the polyester film base material. It is preferable from the viewpoint of film stability.

Although the inorganic particles to be used are not particularly limited, inorganic particles having an average particle diameter of 0.1 to 4.0 μm are preferable, and inorganic particles having an average particle diameter of 0.3 to 1.5 μm are particularly preferable. Specifically, white pigments such as titanium oxide, barium sulfate, calcium carbonate, and zinc sulfide are preferred, and these may be mixed. In addition, inorganic particles commonly contained in films such as silica, alumina, talc, kaolin, clay, calcium phosphate, mica, hectorite, zirconia, tungsten oxide, lithium fluoride, calcium fluoride, calcium sulfate, etc. You can use them together.

Furthermore, the easy-adhesive polyester film for in-mold labels of the present invention is preferably an easy-adhesive microvoid-containing polyester film having an apparent density of 0.3 to 1.3 g/cm ³ .

In addition, the cavity lamination number density is 0.20/μm or more, preferably 0.25/μm or more, and more preferably 0.30/μm or more, from the viewpoint of achieving both cushioning properties and surface peel strength. Certain readily adhering white voided polyester films are also preferred. As a result, the easy-adhesive white void-containing polyester film for in-mold labels obtained is excellent in printing clearness and processability during printing. Here, the void lamination number density (pieces/μm) is defined by the formula: number of voids in the film thickness direction (pieces)/film thickness (μm). The upper limit of the cavity lamination number density is preferably 0.80/μm, more preferably 0.55/μm, from the viewpoint of cavity generation efficiency. As a method to adjust the same density to the above range, in addition to adjusting the addition amount, type, viscosity, etc. of the incompatible thermoplastic resin, changing the screw shape of the extruder, and adding a static mixer to the molten resin flow path Although a method such as installation is used, it is not limited to this.

These easy-adhesive white void-containing polyester films for in-mold labels further improve the opacity by causing light scattering at the interface between the fine voids contained in the film and the matrix polyester, and the inorganic particles are added. is particularly useful because it can reduce the Furthermore, by containing fine cavities, the weight of the base film itself can be reduced, so that handling is facilitated, and economic effects such as reduction in raw material costs and transportation costs are also large.

As a method for obtaining such an easily adhesive white void-containing polyester film for an in-mold label, the thermoplastic polyester resin as the matrix is kneaded with a thermoplastic resin incompatible with the polyester resin as described above, A known method that has already been disclosed, such as a method of generating cavities around the immiscible resin fine particles by stretching a sheet in which the immiscible resin is dispersed in the form of fine particles in a polyester resin at least uniaxially. can be used.

Further, the thickness of the obtained easily adhesive white void-containing polyester film for in-mold label is preferably 5 to 300 μm. In particular, the thickness of the white laminated polyester film having a void lamination number density of 0.20/μm or more is preferably 20 to 300 μm, more preferably 38 to 250 μm.

The desired whiteness when used in printing materials or the like can be represented by color values. In particular, the color L value is a measure of lightness, and the higher the value, the whiter the color. Furthermore, the higher the color b value, the stronger the yellowish color, and the lower the color b value, the stronger the bluish color. In other words, when the L value is high and the b value is low, the whiteness is high, and the whiteness is strong when visually observed. The sharpness at the time of printing is improved.

(Easy adhesion layer)
The easy-adhesive polyester film for in-mold labels of the present invention has antistatic agent back transfer properties, UV ink, water-based flexographic ink, solvent type, oxidation polymerization type ink, melt type thermal transfer ink, and thermoplastic resin such as polyester. In order to improve the adhesion to the in-mold molded container, on at least one side thereof, an easy adhesion layer formed by curing a composition containing an ion-conducting antistatic agent, a polycarbonate urethane resin, and a polyester resin is formed. A form in which it is preferable to be laminated has been reached. The easy adhesion layer is considered to be formed by curing a cationic antistatic agent or anionic antistatic agent, polycarbonate urethane resin or polyester resin, but expresses the chemical structure itself after curing. Therefore, it is expressed as being formed by curing a composition containing a cationic or anionic antistatic agent, a polycarbonate urethane resin, and a polyester resin. The easy-adhesion layer may be provided on both sides of the polyester film substrate, or may be provided on only one side of the polyester film substrate and a different resin coating layer may be provided on the other side.

In the present invention, it is preferable that the easy-adhesion layer surface of the easy-adhesion polyester film for in-mold label has antistatic properties such that the surface resistivity is 1.0×10 ¹³ Ω/sq or less. When the surface resistivity of the easy-adhesion layer surface is 1.0×10 ¹³ Ω/sq or less, there is no adsorption of dust due to friction or static electricity generated during peeling, resulting in good print quality and high print quality. It is preferable because there is no scattering of toner particles. In addition, when the films are charged and attracted to each other, it is possible to prevent phenomena such as poor clearing and double feeding during transportation, which is preferable. The heat-adhesive layer is preferable from the viewpoint of design because it prevents pinhole-like defects by preventing adsorption of dust and maintains smoothness when heat-bonded to a container. The surface resistivity of the easy-adhesion layer surface is more preferably 5.0×10 ¹² Ω/sq or less, still more preferably 1.0×10 ¹² Ω/sq or less. On the other hand, when the surface specific resistance value is 1.0×10 ⁸ Ω/sq or more, the polarity does not become too high and the easy adhesion with various inks is good, which is preferable. It is more preferably 5.0×10 ⁸ Ω/sq or more, and particularly preferably 1.0×10 ⁹ Ω/sq or more.

In the present invention, another polyester film is brought into contact with the easy-adhesion layer surface of the easy-adhesion polyester film and held at 50° C. under a pressure of 1 kg/cm ² for 3 days, and then the surface specific resistance value of the easy-adhesion layer surface is preferably 1.0×10 ¹³ Ω/sq or less. By having the above properties, for example, the antistatic agent present in the easy-adhesion layer of the easy-adhesion polyester film wound into a roll is difficult to migrate (set-off) to the opposite surface in contact, This means that the antistatic property of the easy-adhesion layer is likely to be maintained. It is preferable that the surface resistivity of the easy-adhesion layer surface after the contact treatment under the specific conditions is 1.0×10 ¹³ Ω/sq or less because durable antistatic properties can be obtained. The surface resistivity of the easy-adhesion layer surface after the contact treatment under the specific conditions is more preferably 5.0×10 ¹² Ω/sq or less, and still more preferably 1.0×10 ¹² Ω/sq. sq or less. On the other hand, when the surface resistivity after the contact treatment under the specific conditions is 1.0×10 ⁸ Ω/sq or more, the polarity does not become too high, and various inks and molded containers made of thermoplastic resin such as polyester are used. Etc., the easy adhesion is good and preferable. It is more preferably 5.0×10 ⁸ Ω/sq or more, and particularly preferably 1.0×10 ⁹ Ω/sq or more.

In the present invention, another polyester film is brought into contact with the easy-adhesion layer surface and held at 50° C. under a pressure of 1 kg/cm ² for 3 days, and then the other polyester film in contact with the easy-adhesion layer surface is It is preferable that the surface specific resistance value of the surface of the film is 1.0×10 ¹⁴ Ω/sq or more. By having the above properties, for example, the antistatic agent present in the easy-adhesion layer of the easy-adhesion polyester film wound into a roll is difficult to migrate (set-off) to the opposite surface in contact, It means that the antistatic property of the easy-adhesion layer of the easy-adhesion polyester film is easily maintained, and even when the easy-adhesion coating layer (easy-adhesion layer) is used as the heat-adhesive layer for the in-mold label, It is preferable because the mold is less likely to be contaminated (whitened) when it comes into contact with the mold. Since the mold is less likely to be contaminated, the smoothness at the time of thermal adhesion is maintained, the design is good, and the releasability of the molded product is maintained well, which is preferable. The surface specific resistance value of the surface of the other polyester film after the contact treatment under the specific conditions is more preferably 1.0×10 ¹⁴ Ω/sq or more, more preferably 5.0×10 ¹⁴ Ω. /sq or more is more preferable.

In the present invention, another polyester film is brought into contact with the easy-adhesion layer surface of the easy-adhesion polyester film for in-mold labels, and after being held at 60° C. and 90% temperature and humidity under a pressure of 1 kg/cm ² for 3 days. It is preferable that the easy-adhesion layer surface has a surface specific resistance value of 1.0×10 ¹³ Ω/sq or less. In such a moist and hot environment as described above, the antistatic agent in the easy-adhesion layer is likely to migrate to the other surface. 1.0 × 10 ¹³ Ω / sq or less, for example, even if the easy-adhesive polyester film wound into a roll is left in a hot and humid environment, the antistatic agent present in the easy-adhesion layer does not come into contact. This means that the antistatic property of the easy-adhesive polyester film is easily retained because it is difficult to migrate (set-off) to the opposite side. The surface resistivity of the easy-adhesion layer surface after the contact treatment in the moist heat environment is more preferably 1.0×10 ¹³ Ω/sq or less, and more preferably 9.0×10 ¹² Ω/sq or less. is more preferred. On the other hand, when the surface resistivity after the contact treatment under the above-mentioned moist heat conditions is 1.0×10 ⁸ Ω/sq or more, the polarity does not become too high and various inks and molded containers made of thermoplastic resin such as polyester are used. Etc., the easy adhesion is good and preferable. More preferably, it is 5.0×10 ⁸ Ω/sq or more.

In the present invention, another polyester film is brought into contact with the easy-adhesion layer surface of the easy-adhesion polyester film for in-mold labels, and after being held at 60° C. and 90% temperature and humidity under a pressure of 1 kg/cm ² for 2 days. It is preferable that the surface specific resistance value of the other polyester film that is in contact with the surface of the easy adhesion layer is 1.0×10 ¹³ Ω/sq or more. In such a moist and heat environment, it is thought that the antistatic agent in the easy-adhesion layer is likely to migrate to the other surface. That the surface resistivity value of the surface of the polyester film of is 1.0 × 10 ¹³ Ω/sq or more, for example, even if the easily adhesive polyester film wound up in a roll is left in a moist and hot environment, This means that the antistatic agent present in the easy-adhesion layer is less likely to migrate (set-off) to the opposite side in contact, and the antistatic properties of the easy-adhesion polyester film are easily maintained. More preferably, another polyester film is brought into contact with the easy-adhesion layer surface of the easy-adhesion polyester film, and the surface of the easy-adhesion layer is held at 60° C. and 90% temperature and humidity under a pressure of 1 kg/cm ² for 3 days. The surface specific resistance value of the surface of another polyester film that was in contact with is 1.0×10 ¹³ Ω/sq or more.

In the present invention, when evaluating the migration of the antistatic agent, the easy-adhesion layer of the easy-adhesion polyester film for in-mold labels of the present invention is brought into contact with another polyester film. A case where both surfaces have easy-adhesion layers is also assumed, and in that case, if the easy-adhesion polyester films for in-mold labels of the present invention are overlapped with each other, it is difficult to make an accurate evaluation. The polyester film used does not have an easy-adhesion layer.

The constituent components of the easy-adhesion layer will be described in detail below.
(ion-conducting antistatic agent)
As an antistatic agent, an antistatic agent capable of suppressing migration to the back surface of other articles or the film itself with which it comes into contact is preferred. For example, the functional group is nonionic such as sorbitan type, ether type, ester type, sorbitol type, glucose type, etc.; , anionic surfactants such as alkyl sulfate type, alkyl phosphate type, phosphate ester salt type and sulfate ester salt type, and amphoteric surfactant types such as betaine type, amino acid type and amino sulfate type, or polymer types. .

In the above antistatic agent, the counter ion of the quaternary ammonium base is not particularly limited as long as it is an anionic compound, but is preferably halogen ion, mono- or polyhalogenated alkyl ion, nitrate ion, sulfate ion. , an alkylsulfate ion, a sulfonate ion or an alkylsulfonate ion, preferably the stability of the surface specific resistance value, the stability of the coating liquid, the ink adhesion, and the migration of the antistatic agent to other articles or the back surface Ethosulfate salts are preferred for suppressing

Furthermore, polyethyleneimine, polydimethyldiallylammonium salt, polyalkylenepolyamine dicyanodiamide ammonium condensate, polyvinylpyridinium halide, (meth)acrylic acid alkyl quaternary ammonium salt, (meth)acrylamidoalkyl quaternary ammonium salt, ω-chloro-poly (oxyethylene-polymethylene-alkyl quaternary ammonium salt), polyvinylbenzyltrimethylammonium salt, polystyrene cationic polymer, poly(meth)acrylic cationic polymer (methyl methacrylate, ethyl acrylate, 2-hydroxyethyl methacrylate, trimethylamino chloride ethyl methacrylate, etc.), polyvinylpyridine-based polymer, cyclic integral type polymer, linear integral type polymer, polymer of aromatic vinyl monomer having two or more pendant quaternary ammonium ion groups, pyrrolidium in main chain Examples include polymers having rings. These polymers may be homopolymers or copolymers. Known copolymerizable monomers can be used to produce these polymers. In order to control the mixability of the coating liquid and the amount of the antistatic agent component present on the surface of the easy-adhesion layer, an antistatic agent having a linear alkyl group is preferable. It is preferably an antistatic agent having a class ammonium base.

Therefore, in the antistatic agent having a linear alkyl group and a quaternary ammonium base, the number of carbon atoms in the alkyl chain is preferably 10 to 25, more preferably 12 to 19, 14 to 18 are particularly preferred. In view of the interaction between the same molecules and the suppression of migration to the back due to the molecular length, the above range is preferable.

The molecular weight of the quaternary ammonium base having a linear alkyl group is preferably 200 or more and preferably 700 or less. More preferably 400 or more and 600 or less. When the molecular weight is 200 or less, the surface specific resistance value is likely to be expressed, but back migration cannot be suppressed. When the molecular weight is 700 or more, it is difficult to develop a surface specific resistance value, and aggregation is likely to occur due to interaction with resin functional groups during coating liquid preparation.

In addition, in the molecular structure of the cationic antistatic agent having a nitrogen element, at least one amide bond or urethane bond may be included between the linear alkyl chain and the quaternary ammonium base.

(polycarbonate urethane resin)
The urethane resin having a polycarbonate structure in the present invention preferably has a urethane bond partial structure derived from at least a polycarbonate polyol component and a polyisocyanate component, and further contains a chain extender as necessary. Furthermore, a polyisocyanate having a branched structure is synthesized and polymerized by the presence of 3 or more terminal functional groups in any of the raw materials constituting the molecular chain to form a branched molecular chain structure. It is preferably introduced by

The polycarbonate urethane resin of the present invention and the urethane resin having a branched structure preferably have a lower limit of 3 terminal functional groups in the molecular chain, more preferably 4, depending on the branched structure. When the number is 3 or more, the blocking resistance when water is attached can be improved, which is preferable. The upper limit of the number of terminal functional groups in the molecular chain of the urethane resin having a polycarbonate structure in the present invention is preferably 6 due to its branched structure. When the number is 6 or less, the resin can be stably dispersed in the aqueous solution, which is preferable.

The polycarbonate polyol component used for synthesizing and polymerizing the polycarbonate urethane resin in the present invention preferably contains an aliphatic polycarbonate polyol having excellent heat resistance and hydrolysis resistance. Aliphatic polycarbonate polyols include aliphatic polycarbonate diols and aliphatic polycarbonate triols, and aliphatic polycarbonate diols can be preferably used. Aliphatic polycarbonate diols used for synthesizing and polymerizing the urethane resin having a polycarbonate structure in the present invention include, for example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5 - diols such as pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,8-nonanediol, neopentyl glycol, diethylene glycol and dipropylene glycol; Aliphatic polycarbonate diols obtained by reacting one or more of them with, for example, carbonates such as dimethyl carbonate, ethylene carbonate and phosgene.

The number average molecular weight of the polycarbonate polyol in the present invention is preferably 1,000 to 3,000. More preferably 1200-2900, most preferably 1500-2800. When it is 1000 or more, the ink adhesion can be improved, which is preferable. When it is 3000 or less, it is preferable because the back migration of the antistatic agent can be suppressed.

Examples of the polyisocyanate used for the synthesis and polymerization of the polycarbonate urethane resin in the present invention include aromatic-aliphatic diisocyanates such as xylylene diisocyanate, isophorone diisocyanate and 4,4-dicyclohexylmethane diisocyanate, 1,3-bis(isocyanatomethyl ) Alicyclic diisocyanates such as cyclohexane, hexamethylene diisocyanate, and aliphatic diisocyanates such as 2,2,4-trimethylhexamethylene diisocyanate, or these compounds are added singly or in combination with trimethylolpropane or the like in advance. and polyisocyanates. When the above aromatic-aliphatic diisocyanates, alicyclic diisocyanates, or aliphatic diisocyanates are used, there is no problem of yellowing, which is preferable. Moreover, it does not form an excessively hard coating film, and is favorable for obtaining a surface specific resistance value due to the antistatic agent, which is preferable.

Chain extenders include glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol and 1,6-hexanediol, polyhydric alcohols such as glycerin, trimethylolpropane and pentaerythritol, and ethylenediamine. , hexamethylenediamine, and piperazine, amino alcohols such as monoethanolamine and diethanolamine, thiodiglycols such as thiodiethylene glycol, and water.

In order to form a branched structure in the urethane resin, for example, the polycarbonate polyol component, polyisocyanate, and chain extender are allowed to react at an appropriate temperature and time, and then trifunctional or higher hydroxyl groups or isocyanate groups are added. A method of adding a compound having a compound and further advancing the reaction can be preferably employed.

Specific examples of compounds having a trifunctional or higher hydroxyl group include caprolactone triol, glycerol, trimethylolpropane, butanetriol, hexanetriol, 1,2,3-hexanetriol, 1,2,3-pentanetriol, 1,3 ,4-hexanetriol, 1,3,4-pentanetriol, 1,3,5-hexanetriol, 1,3,5-pentanetriol and polyethertriol. Examples of the polyether triols include, for example, glycerin, alcohols such as trimethylolpropane, diethylenetriamine, and the like, using one or more compounds having three active hydrogens as initiators, ethylene oxide, propylene oxide, and butylene. Compounds obtained by addition polymerization of one or more of monomers such as oxides, amylene oxides, glycidyl ethers, methyl glycidyl ethers, t-butyl glycidyl ethers, and phenyl glycidyl ethers can be mentioned.

A specific example of the compound having a trifunctional or higher isocyanate group is a polyisocyanate compound having at least three or more isocyanate (NCO) groups in one molecule. In the present invention, trifunctional or higher isocyanate compounds are aromatic diisocyanates, aliphatic diisocyanates, araliphatic diisocyanates, alicyclic diisocyanates having two isocyanate groups. and adducts.
Aromatic diisocyanates include, for example, 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate isocyanate, 4,4'-toluidine diisocyanate, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and the like.
Aliphatic diisocyanates are, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2, 4,4-trimethylhexamethylene diisocyanate and the like.
Examples of araliphatic diisocyanates include xylylene diisocyanate, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate.
Alicyclic diisocyanates include, for example, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (also known as IPDI, isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4'-methylenebis(cyclohexylisocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, and the like.
The burette body is a self-condensed product having a burette bond formed by self-condensation of an isocyanate monomer, and examples thereof include a burette body of hexamethylene diisocyanate.
A nurate compound is a trimer of an isocyanate monomer, and examples thereof include a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, a trimer of tolylene diisocyanate, and the like.
The adduct refers to a tri- or higher functional isocyanate compound obtained by reacting the above isocyanate monomer with a tri- or higher-functional low-molecular-weight active hydrogen-containing compound, for example, a compound obtained by reacting trimethylolpropane and hexamethylene diisocyanate. , a compound obtained by reacting trimethylolpropane and tolylene diisocyanate, a compound obtained by reacting trimethylolpropane and xylylene diisocyanate, a compound obtained by reacting trimethylolpropane and isophorone diisocyanate, and the like.

Examples of the chain extender having a functional group number of 3 or more include trimethylolpropane and alcohols having a hydroxy group of 3 or more functional groups such as pentaerythritol, which are mentioned in the above description of the chain extender.

The easy-adhesion layer in the present invention is preferably provided by an in-line coating method, which will be described later, using a water-based coating liquid. Therefore, it is desirable that the urethane resin of the present invention has water solubility or water dispersibility. The term "water-soluble or water-dispersible" means dispersing in water or an aqueous solution containing less than 50% by mass of a water-soluble organic solvent.

In order to impart water dispersibility to the urethane resin, a sulfonic acid (salt) group or a carboxylic acid (salt) group can be introduced (copolymerized) into the urethane molecular skeleton. In order to maintain moisture resistance, it is preferable to introduce a weakly acidic carboxylic acid (salt) group, and it is preferable to suppress the interaction (gelling) with the cationic antistatic agent. Furthermore, nonionic groups such as polyoxyalkylene groups can also be introduced.

In order to introduce a carboxylic acid (salt) group into a urethane resin, for example, as a polyol component, a polyol compound having a carboxylic acid group such as dimethylolpropanoic acid or dimethylolbutanoic acid is introduced as a copolymerization component to form a salt. Neutralize with an agent. Specific examples of salt-forming agents include ammonia, trialkylamines such as trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine and tri-n-butylamine; -N-dialkylalkanolamines such as alkylmorpholines, N-dimethylethanolamine and N-diethylethanolamine. These can be used alone or in combination of two or more.

When a polyol compound having a carboxylic acid (salt) group is used as a copolymerization component in order to impart water dispersibility, the composition molar ratio of the polyol compound having a carboxylic acid (salt) group in the urethane resin is When the total polyisocyanate component of is 100 mol %, the content is preferably 3 to 60 mol %, preferably 5 to 40 mol %. When the composition molar ratio is 3 mol % or more, water dispersibility is obtained, which is preferable. Further, when the composition molar ratio is 60 mol % or less, water resistance is maintained and moist heat resistance is obtained, which is preferable.

The urethane resin in the present invention may have a blocked isocyanate structure at its terminal for improving toughness.

(crosslinking agent)
In the present invention, a blocked isocyanate may be added as a cross-linking agent to the easily adhesive layer-forming composition. Tri- or higher functional blocked isocyanates are more preferred, and tetra- or higher functional blocked isocyanates are particularly preferred. It is possible to control the antistatic property of the surface of the easily adhesive layer and to suppress the migration of the antistatic agent to the back by these.

The blocked isocyanate in the present invention can introduce a hydrophilic group into the precursor polyisocyanate in order to impart water solubility or water dispersibility. Hydrophilic groups include (1) quaternary ammonium salts of dialkylaminoalcohols and quaternary ammonium salts of dialkylaminoalkylamines, etc., (2) sulfonates, carboxylates, phosphates, etc., and (3) alkyl groups. Polyethylene glycol, polypropylene glycol and the like with one end blocked can be mentioned. When a hydrophilic site is introduced, it becomes (1) cationic, (2) anionic, and (3) nonionic. Of these, anionic and nonionic resins that are easily compatible with each other are preferable because many other water-soluble resins are anionic. In addition, the anionic resin is excellent in compatibility with other resins, and the nonionic resin does not have an ionic hydrophilic group, so it is also preferable for improving the resistance to moist heat.

As the anionic hydrophilic group, those having a hydroxyl group for introduction into the polyisocyanate and a carboxylic acid group for imparting hydrophilicity are preferred. Examples include glycolic acid, lactic acid, tartaric acid, citric acid, oxybutyric acid, oxyvaleric acid, hydroxypivalic acid, dimethylolacetic acid, dimethylolpropanoic acid, dimethylolbutanoic acid, and polycaprolactone having a carboxylic acid group. Organic amine compounds are preferred for neutralizing carboxylic acid groups. For example, ammonia, methylamine, ethylamine, propylamine, isopropylamine, butylamine, 2-ethylhexylamine, cyclohexylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine , linear, branched 1, 2 or tertiary amines having 1 to 20 carbon atoms such as ethylenediamine, cyclic amines such as morpholine, N-alkylmorpholine and pyridine, monoisopropanolamine, methylethanolamine, methylisopropanolamine, hydroxyl group-containing amines such as dimethylethanolamine, diisopropanolamine, diethanolamine, triethanolamine, diethylethanolamine and triethanolamine;

The nonionic hydrophilic group preferably has 3 to 50, more preferably 5 to 30 repeating units of ethylene oxide and/or propylene oxide of polyethylene glycol or polypropylene glycol end-capped with an alkyl group. When the repeating unit is too small, the compatibility with the resin is deteriorated, resulting in an increase in haze. A nonionic, anionic, cationic, or amphoteric surfactant can be added to the blocked isocyanate of the present invention in order to improve water dispersibility. For example, nonionic compounds such as polyethylene glycol and polyhydric alcohol fatty acid esters; anionic compounds such as fatty acid salts, alkyl sulfates, alkylbenzenesulfonates, sulfosuccinates and alkylphosphates; cationic compounds such as alkylamine salts and alkylbetaines; Examples thereof include surfactants such as carboxylic acid amine salts, sulfonic acid amine salts, and sulfate ester salts.

Moreover, a water-soluble organic solvent can be contained in addition to water. For example, the organic solvent used in the reaction or it can be removed and another organic solvent can be added.

Other disclosed compounds can be applied and added as means for improving adhesion. Even if other cross-linking agents are used to improve the adhesion durability of the easily adhesive layer, it is possible to further improve the adhesion under high temperature and high humidity conditions. Specific cross-linking agents include urea-based, epoxy-based, melamine-based, oxazoline-based, carbodiimide-based, and the like. In addition, a catalyst or the like can be appropriately used as necessary in order to accelerate the cross-linking reaction.

(polyester resin)
The polyester resin used to form the easy-adhesion layer in the present invention may be a linear one, but is more preferably a polyester resin having a dicarboxylic acid and a diol having a branched structure as its constituent components. Preferably. The dicarboxylic acid referred to here is mainly composed of terephthalic acid, isophthalic acid or 2,6-naphthalenedicarboxylic acid, as well as aliphatic dicarboxylic acids such as adipic acid and sebacic acid, terephthalic acid, isophthalic acid, phthalic acid, 2, Aromatic dicarboxylic acids such as 6-naphthalenedicarboxylic acid are included. A branched glycol is a diol having a branched alkyl group, such as 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- and hexyl-1,3-propanediol.

It can be said that the branched glycol component, which is the more preferred embodiment of the polyester resin, is contained in the total glycol component in a proportion of preferably 10 mol % or more, more preferably 20 mol % or more. When it is 10 mol % or more, the crystallinity does not become too high, and the adhesiveness of the easy-adhesion layer becomes good, which is preferable. The upper limit of the glycol component in all glycol components is preferably 80 mol% or less, more preferably 70% by mass. When it is 80 mol % or less, the concentration of the oligomer, which is a by-product, is suppressed, and the transparency of the easy-adhesion layer is favorable, which is preferable. Ethylene glycol is most preferable as the glycol component other than the above compounds. Diethylene glycol, propylene glycol, butanediol, hexanediol, 1,4-cyclohexanedimethanol, or the like may be used in small amounts.

Terephthalic acid or isophthalic acid is most preferable as the dicarboxylic acid as a constituent of the polyester resin. In addition to the above dicarboxylic acid, it is preferable to copolymerize 5-sulfoisophthalic acid or the like in the range of 1 to 10 mol% in order to impart water dispersibility to the copolymerized polyester resin. 5-sulfoisophthalic acid, 5-sodiumsulfoisophthalic acid and the like can be mentioned. A polyester resin containing a dicarboxylic acid having a naphthalene skeleton may be used, but its quantitative ratio is 5 mol% or less in the total carboxylic acid component in order to suppress deterioration of adhesion to UV ink. is preferred and may not be used.

As a constituent component of the polyester resin, a triol or tricarboxylic acid may be included to the extent that the properties of the polyester resin are not impaired.

The polyester resin may contain a polar group other than the carboxyl group. For example, sulfonic acid metal bases, phosphoric acid groups, and the like can be mentioned, and one or more of these can be used. As a method for introducing a sulfonic acid metal base, a metal salt such as 5-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, 5-[4-sulfophenoxy]isophthalic acid, or 2-sulfo-1, Dicarboxylic acids or glycols containing sulfonic acid metal bases such as metal salts such as 4-butanediol and 2,5-dimethyl-3-sulfo-2,5-hexanediol are added to the total amount of polycarboxylic acid components or polyol components. A method of using 10 mol % or less, preferably 7 mol % or less, more preferably 5 mol % or less is mentioned. If it exceeds 10 mol %, the hydrolysis resistance of the resin itself and the water resistance of the coating film tend to decrease.

The resin solid content concentration in the coating liquid means the total solid content concentration of the polyester resin, the urethane resin having a polycarbonate structure, and the cross-linking agent. It is desirable to adjust the resin solid content concentration in the coating liquid to 5 to 17%. When the resin solid content concentration is 5% or more, the thickness of the easy-adhesion layer after drying and curing does not become too thin, and the easy-adhesion of UV-curable inks and the like is favorable, which is preferable. On the other hand, when the resin solid content concentration is 17% or less, sufficient crosslinkability can be obtained when the crosslinker is contained, and migration of the antistatic agent to other articles or the back surface can be suppressed, and blocking phenomenon can also occur. It is preferable because it can be suppressed.

When the total solid content contained in the composition for forming the easy-adhesion layer is taken as 100% by mass, it is desirable that the ion-conducting antistatic agent is contained in an amount of 1 to 8% by mass. If the specified range is satisfied, antistatic performance can be obtained. Furthermore, it is a preferable range because the antistatic component does not migrate to other articles or the back surface after heating and moist heat treatment.

It is preferable that the content of the urethane resin having a polycarbonate structure is 5 to 50% by mass when the total solid content of the polyester resin, the urethane resin having a polycarbonate structure, and the cross-linking agent is 100% by mass. Satisfying the above range is preferable because good affinity with various materials and UV inks can be achieved and adhesion can be achieved. If it is in the above-specified range, it is preferable because it has excellent adhesion and antistatic performance, and the antistatic agent can suppress migration to other articles or the back surface even under moist heat resistance.

The upper limit of the content of the cross-linking agent is preferably 50% by mass when the total of the solid content of the polyester resin, the urethane resin having a polycarbonate structure, and the cross-linking agent is 100% by mass. By satisfying the above range, the crosslinkability of the easy-adhesion layer is increased, the affinity with UV ink and the like is improved, and the antistatic property is easily expressed, which is preferable. Further, the strength of the easy-adhesion layer is maintained in the moisture-resistant treatment, and the antistatic agent is preferable because it can suppress migration to other articles or the back surface.

When the total solid content of the polyester resin, the urethane resin having a polycarbonate structure, and the three cross-linking agents is taken as 100% by mass, the polyester resin content is preferably 10 to 70% by mass. By satisfying the above range, good affinity with various materials and UV inks and adhesion can be achieved. In particular, it is preferable because the adhesiveness to the polyester film substrate is improved. In addition, it is preferable to use a cationic antistatic agent because gelling of the coating liquid due to interaction can be suppressed.

(Additive)
In the easy adhesion layer in the present invention, known additives such as surfactants, Ph adjusters, antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, organic Lubricants, pigments, dyes, organic or inorganic particles, antistatic agents, nucleating agents and the like may be added.

The above surfactants are sometimes used in expectation of effects such as solubilizing agents, dispersing agents, antifoaming agents, wettability aids, and the like. The hydrophilic part of the surfactant is divided into ionic (cationic, anionic, amphoteric) and nonionic. When used as a water-based coating material, a polyester film used as a substrate is used because of its low surface energy and poor wettability. Therefore, it is often used as a wettability aid for adjusting the surface tension of water-based coating materials. Although not particularly limited, the surfactant is preferably one that can lower the surface tension of the coating solution to 50 dyne/cm or less, preferably 40 dyne/cm or less, and promotes wetting of the polyester film. Trimethylammonium salt, dialkyldimethylammonium salt, alkylbenzyldimethylammonium salt, monoalkyl sulfate, alkylpolyoxyethylene sulfate, alkylbenzenesulfonate, monoalkylphosphate, alkyldimethylamine oxide, alkylcarboxybetaine, polyoxyethylene Alkyl ethers, fatty acid sorbitan esters, alkyl polyglucosides, fatty acid diethanolamides, alkyl monoglyceryl ethers, etc., among which polyether-modified silicones are preferred.

The amount of the surfactant to be added is preferably 0.1% by mass or more and 1.0% by mass or less when the total solid mass in the coating liquid is 100% by mass. It is more preferably in the range of 0.2% by mass to 0.8% by mass. A content of 0.1% by mass or more is preferable because a wettability effect as a surfactant can be obtained. Moreover, when it is 1.0% by mass or less, the easy adhesion is maintained well, which is preferable.

Among the above additives, a pH adjuster may be used in some cases. Acids for adjusting the pH include inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid, and organic acids such as oxalic acid, formic acid, citric acid and acetic acid. be done. In the adjustment with a water-based coating material, the pH is preferably in the range of pH 5 to 9, and more preferably in the range of pH 6 to 8.5. If the pH is 5 or less, the coating machine may be corroded, and the effect of accelerating the separation of the blocking agent when a blocked isocyanate is selected as the cross-linking agent is reduced. Moreover, if the pH is 9 or higher, the polyester resin used as the resin binder is hydrolyzed, which impairs adhesion and durability, which is not preferable.

Inert particles may be contained in the easy-adhesion layer in order to reduce the glossiness of the easy-adhesion layer surface.

The easy-adhesion layer may contain lubricant particles in order to impart slipperiness, mattness, ink absorbency, etc. to the surface. The particles may be inorganic particles or organic particles, and are not particularly limited, and include (1) silica, kaolinite, talc, light calcium carbonate, heavy calcium carbonate, zeolite, alumina, barium sulfate, carbon black, zinc oxide, zinc sulfate, zinc carbonate, zirconium oxide, titanium dioxide, aluminum silicate, diatomaceous earth, calcium silicate, aluminum hydroxide, calcium carbonate, magnesium carbonate, calcium phosphate, magnesium hydroxide, barium sulfate, etc. Inorganic particles, (2) acrylic or methacrylic, vinyl chloride, vinyl acetate, nylon, styrene/acrylic, styrene/butadiene, polystyrene/acrylic, polystyrene/isoprene, polystyrene/isoprene, methyl methacrylate /Butyl methacrylate-based, melamine-based, polycarbonate-based, urea-based, epoxy-based, urethane-based, phenol-based, diallyl phthalate-based, polyester-based organic particles, etc., to give the easy-adhesion layer appropriate slipperiness. Silica is particularly preferably used.

The average particle size of the inert particles is preferably 0.1 to 2.4 μm, more preferably 0.3 to 2.0 μm. If the average particle size of the inert particles is 0.04 μm or less, the glossiness of the film surface may increase. Conversely, if it exceeds 2.4 μm, the particles tend to come off from the easy-adhesion layer, causing powder to fall off during various processes such as film running.

The average particle size can be determined as a result of morphological observation with a microscope using a scanning electron microscope, a transmission electron microscope, or the like. Specifically, the average value of the diameters of 20 arbitrarily selected particles in these microscopic observations is adopted. The shape of the particles is not particularly limited as long as it satisfies the object of the present invention, and spherical particles and non-spherical irregular particles can be used. The particle diameter of amorphous particles can be calculated as a circle equivalent diameter. The circle-equivalent diameter is a value obtained by dividing the observed particle area by π, calculating the square root, and doubling the result.

When it is desired to increase the glossiness of the easy-adhesion layer surface, it is also preferable not to include particles in the easy-adhesion layer.

It is also a preferable form that the easy-adhesion layer provides surface unevenness by embossing in order to impart slipperiness and air release to the mold metal for in-mold molding.

(Production of easy-adhesive polyester film for in-mold labels)
The method for producing the easy-adhesive polyester film for in-mold labels of the present invention is arbitrary and not particularly limited. After that, a general method of stretching the unstretched film can be used.

In the easy-adhesive polyester film for in-mold labels of the present invention, a thermoplastic resin incompatible with the polyester resin may be dispersed in the polyester resin in the process of melting and extruding the film raw material. In the examples of the present invention, the polyester resin and the thermoplastic resin incompatible with the polyester resin were supplied in the form of pellets, but the present invention is not limited to this.

The raw material to be fed into the extruder for melt-molding into a film is prepared by mixing these resins in pellets according to the intended composition. However, when a polyester resin and a polyolefin resin are used as the raw materials for the polyester film of the present invention, the specific gravities of the resins differ greatly between the two. preferably added. A suitable method for preventing segregation is a method in which part or all of the raw material resins are previously combined, kneaded and pelletized to form a masterbatch pellet. Although this method was used in the examples of the present invention, it is not particularly limited as long as it does not interfere with the effects of the present invention.

In addition, in the extrusion of a mixed system of these polyester resins and resins incompatible with polyester resins, even after mixing and finely dispersing in a molten state, re-agglomeration due to the function of reducing the interfacial energy of the resins. have a tendency to This is a phenomenon in which the void forming agent is coarsely dispersed during the extrusion molding of the unstretched film and hinders the development of desired physical properties.

In order to prevent this, it is preferable to finely disperse the cavity forming agent in advance using a twin-screw extruder, which has a higher mixing effect, when forming a mixed film as described above. Moreover, when this is difficult, as an auxiliary means, it is also preferable to feed the starting resin from the extruder through a static mixer to a feed block or a die. As the static mixer used here, a static mixer, an orifice, or the like can be used. However, when these methods are adopted, it is necessary to pay attention to the fact that thermally degraded resin may remain in the melt line.

In addition, the immiscible resin once dispersed in the form of fine particles in the polyester resin tends to reaggregate over time under a low-shear molten state, so the melt from the extruder to the die A fundamental solution is to reduce the residence time in the line. In the present invention, the residence time in the melt line is preferably 30 minutes or less, more preferably 15 minutes or less.

The conditions under which the unstretched film obtained as described above is stretched and oriented are closely related to the physical properties of the film. Hereinafter, the stretching and orientation conditions will be described by taking as an example the most common sequential biaxial stretching method, particularly a method in which an unstretched film is stretched in the longitudinal direction and then in the width direction.

In the longitudinal stretching step, the film is stretched 2.5 to 5.0 times in the longitudinal direction with rolls heated to 80 to 120° C. to obtain a uniaxially stretched film. As a heating means, a method using a heating roll or a method using a non-contact heating method may be used, or they may be used in combination. Then, the uniaxially stretched film is introduced into a tenter and stretched 2.5 to 5.0 times in the width direction at a temperature of (Tm-10°C) or less. However, Tm means the melting point of polyester.

In addition, the above biaxially stretched film is subjected to heat treatment as necessary. The heat treatment is preferably carried out in a tenter, preferably in the range of (Tm-60°C) to Tm.

The easy-adhesion layer can be provided after the production of the film or during the production process. In particular, from the viewpoint of productivity, it is preferable to apply the coating liquid to at least one side of the unstretched or uniaxially stretched PET film at any stage of the film manufacturing process to form an easily adhesive layer.

Any known method can be used to apply the coating liquid to the polyester film. For example, reverse roll coating method, gravure coating method, kiss coating method, die coater method, roll brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, impregnation coating method, curtain coating method, etc. be done. These methods can be applied singly or in combination.

In the present invention, the thickness of the easy adhesion layer can be appropriately set in the range of 0.001 to 2.00 μm, but the range of 0.01 to 1.00 μm is preferable in order to achieve both workability and adhesion. , more preferably 0.02 to 0.80 μm, still more preferably 0.05 to 0.50 μm. It is preferable that the thickness of the easy adhesion layer is 0.001 μm or more because the adhesion is good. When the thickness of the easy-adhesion layer is 2.00 μm or less, the transfer of the antistatic agent to other articles or back surface can be suppressed, which is preferable.

EXAMPLES Next, the present invention will be described in detail using examples and comparative examples, but the present invention is not limited to the following examples. First, the evaluation method used in the present invention will be described below.

(1) Antistatic Property Surface Specific Resistance Value Three pieces of 5.00 cm square film were cut out to prepare samples. The surface specific resistance value was measured using a surface resistance measuring device (Hiresta MCP-HT800 manufactured by Nitto Seiko Anaric), applied voltage 500 V, 23 ° C., 65% humidity, JIS K6911 compliant 3 sheets each measured and averaged. .

(2) Evaluation of easy-adhesive layer surface and transferability to other surface under 50° C. pressurized environment Three 5.00 cm squares were cut out of the film and used as samples. Polyester film ^E5001 (thickness 50 μm) manufactured by Toyobo Co., Ltd. and the surface of the easy-adhesive layer of the sample are superimposed on each other. kept for days. The surface specific resistance value of the easy-adhesion layer surface of the sample and the surface of Toyobo polyester film E5001 in contact was measured using a surface resistance measuring instrument (Hiresta MCP-HT800 manufactured by Nitto Seiko Analic), applied voltage 500 V, 23 ° C., 65% humidity. In accordance with JIS K6911, each three sheets were measured, and the average value was calculated.
For the easy-adhesion layer surface of the sample,
○: 1.0×10 ¹³ Ω/sq or less ×: More than 1.0×10 ¹³ Ω/sq For the surface in contact with E5001,
Good: 1.0×10 ¹⁴ Ω/sq or more ×: Less than 1.0×10 ¹⁴ Ω/sq.

(3) Evaluation of easy-adhesion layer surface and transferability to other surface under pressure in a moist and heat-resistant environment Three pieces of 5 cm square were cut out from the film and used as samples. This is superimposed on the polyester film E5001 (thickness 50 μm) manufactured by Toyobo Co., Ltd. and the surface of the easy-adhesive layer of the sample, and using a thermo-hygrostat IG400 manufactured by Yamato Scientific Co., Ltd., 60 ° C., 1 kg under 90% temperature and humidity. /cm ² , two days and three days of pressurization were prepared. The surface specific resistance value of the easy-adhesion layer of the sample and the surface of Toyobo polyester film E5001 in contact was measured using a surface resistance measuring instrument (Hiresta MCP-HT800 manufactured by Nitto Seiko Anaric), applied voltage 500 V, 23 ° C., 65% humidity. Each three sheets were measured according to JIS K6911, and the average value was calculated.
Regarding the easy-adhesion layer surface of the sample, the one that was superimposed and held for 3 days was measured,
〇: Less than 1.0×10 ¹³ Ω/sq ×: More than 1.0×10 ¹³ Ω/sq For the surfaces in contact with E5001, measurements were taken for both the two-day and three-day overlaps. death,
○: 1.0×10 ¹⁴ Ω/sq or more after 3-day overlap △: Less than 1.0×10 ¹⁴ Ω/sq after 3-day overlap and 1 after 2-day overlap .0×10 ¹³ Ω/sq or more ×: Less than 1.0×10 ¹³ Ω/sq overlaid for 2 days.

(4) Adhesion to UV ink UV ink [manufactured by T&K TOKA Co., Ltd., trade name "BEST CURE (registered trademark) UV161 Indigo S" is applied on the easy-adhesion layer on one side of the easy-adhesion polyester film for in-mold labels. ] using a printing machine [manufactured by Mei Seisakusho Co., Ltd., trade name “RI Tester”], and then the film coated with the ink layer is irradiated with ultraviolet rays of 40 mJ/cm ² using a high-pressure mercury lamp. Then, the UV curable ink was cured. Next, using a cellophane adhesive tape (CT405AP-24) manufactured by Nichiban, a 24 mm wide and 50 mm long piece was cut out and completely adhered to the surface of the ink layer with a handy rubber roller so as not to mix air. Thereafter, the adhesive cellophane tape was peeled off vertically, and the remaining area of the printed layer was observed in an area of 24 mm×50 mm, and judged according to the following criteria.
◯: Passed when the remaining area of the printed layer was 99% or more of the whole.
Δ: Passed when the remaining area of the printed layer was 90% or more and less than 99% of the whole.
x: Remaining area of the printed layer was less than 90% of the whole, and was regarded as unsatisfactory.

(5) Adhesion with water-based flexo ink On the easy-adhesion layer on one side of the easy-adhesion polyester film for in-mold label, a water-based flexo ink for surface printing [manufactured by Dainichiseika Kogyo Co., Ltd., trade name "Hydric ( Registered trademark) FCG"], printing is performed using a printing machine [manufactured by Matsuo Sangyo Co., Ltd., trade name "K Printing Proofer"] 150-wire metal plate, and then the ink layer is dried in a dryer oven at 100 ° C., 30 It was cured by heating for a second. Next, using a cellophane adhesive tape (CT405AP-24) manufactured by Nichiban, a 24 mm wide and 50 mm long piece was cut out and completely adhered to the surface of the ink layer with a handy rubber roller so as not to mix air. Thereafter, the adhesive cellophane tape was peeled off vertically, and the remaining area of the printed layer was observed in an area of 24 mm×50 mm, and judged according to the following criteria.
◯: Passed when the remaining area of the printed layer was 99% or more of the whole.
Δ: Passed when the remaining area of the printed layer was 90% or more and less than 99% of the whole.
x: Remaining area of the printed layer was less than 90% of the whole, and was regarded as unsatisfactory.

(6) Adhesion to solvent-curable ink "Screen ink manufactured by Jujo Chemical Co., Ltd.""Trade name Tetoron ink 900-1 series 990 black" is applied on the easy-adhesive layer on one side of an easy-adhesive polyester film for in-mold labels. "Dilution solvent manufactured by Jujo Chemical Co., Ltd.""Trade name Tetoron standard solvent" was used to dilute Tetoron ink: Tetoron standard solvent = 4: 1, using a 250 mesh screen and a squeegee to apply. . After the ink was applied, it was dried and cured at 90° C. for 5 minutes using a dry oven DVS602 manufactured by Yamato Scientific Co., Ltd. Next, using a cellophane adhesive tape (CT405AP-24) manufactured by Nichiban, a 24 mm wide and 50 mm long piece was cut out and completely adhered to the surface of the ink layer with a handy rubber roller so as not to mix air. Thereafter, the adhesive cellophane tape was peeled off vertically, and the remaining area of the printed layer was observed in an area of 24 mm×50 mm, and judged according to the following criteria.
◯: Passed when the remaining area of the printed layer was 99% or more of the whole.
Δ: Passed when the remaining area of the printed layer was 90% or more and less than 99% of the whole.
x: Remaining area of the printed layer was less than 90% of the whole, and was regarded as unsatisfactory.

(7) Adhesion to oxidation polymerization type ink Oxidation polymerization type offset ink [manufactured by Toyo Ink Mfg. Co., Ltd., trade name "TSP400 G ink"] on one side of an easy adhesion layer of an easy adhesion polyester film for in-mold labels. was used to print with a printing machine [manufactured by Akira Seisakusho Co., Ltd., trade name "RI Tester"]. Next, using a cellophane adhesive tape (CT405AP-24) manufactured by Nichiban, a 24 mm wide and 50 mm long piece was cut out and completely adhered to the surface of the ink layer with a handy rubber roller so as not to mix air. Thereafter, the adhesive cellophane tape was peeled off vertically, and the remaining area of the printed layer was observed in an area of 24 mm×50 mm, and judged according to the following criteria.
◯: Passed when the remaining area of the printed layer was 99% or more of the whole.
Δ: Passed when the remaining area of the printed layer was 90% or more and less than 99% of the whole.
x: Remaining area of the printed layer was less than 90% of the whole, and was regarded as unsatisfactory.

(8) Adhesion of melt-type thermal transfer ink On the easy-adhesive layer on one side of the easy-adhesive polyester film for in-mold label, Ricoh's thermal transfer ribbon B110C ink was applied using a thermal transfer printer Scantronics CL4NX-J manufactured by Sato Co., Ltd. A one-dimensional bar code with arbitrary JAN code was printed at a printing speed of 6 inches/second.
Next, using a cellophane adhesive tape (CT405AP-24) manufactured by Nichiban, a 24 mm wide and 50 mm long piece was cut out and completely adhered to the surface of the ink layer with a handy rubber roller so as not to mix air. Thereafter, the adhesive cellophane tape was peeled off vertically, and the printed layer was observed in an area of 24 mm×50 mm, and judged according to the following criteria.
◯: The bar code fine-line printed portion is not peeled off.
Δ: Partially peeled bar code thin line printed portion.
x: The bar code fine-line printed portion is entirely peeled off.

(9) In-mold molding adhesion An easy-adhesive polyester film for in-mold labels is cut into 10 cm × 15 cm pieces, and vacuum is applied to one side of the split mold for blow molding so that the easy-adhesive layer on one side is in contact with the mold. After fixing so that the easy-adhesion layer on the other side faces the resin molding layer side, polyethylene terephthalate (trade name “Unipet (registered trademark), melting point 230°C, manufactured by Nihon Unipet Co., Ltd.) is melted at 280°C. An extruded parison is introduced between the split dies, the split dies are clamped, a compressed air of 0.5 MPa is supplied into the parison, the parison is expanded and molded into a container, and an easy-adhesive polyester film for in-mold labels and heat are applied. The mold was cooled to 25° C. to obtain a resin container to which an easy-adhesive polyester film for in-mold molding with a content of 500 ml was adhered.The easy-adhesive film adhered to the resin container was obtained. No shrinkage deformation was observed, and adhesion to the molded container was judged according to the following criteria.
The test was performed by manually peeling off the four corners of the easily adhesive film.
◯: Adhered to the molded container and not peeled off. Or cohesive failure of the film or bottle.
Δ: Adhered to the molded container, but peeled off due to cracking.
x: Not adhered to the molded container.

(10) Humidity and heat easy adhesion test (6) The sample obtained in the test was subjected to a constant temperature and humidity chamber IG400 manufactured by Yamato Scientific Co., Ltd.
After storing for 3 days at 60° C. and 90% temperature and humidity, the adhesion to the molded product was evaluated according to the following criteria.
◯: Adhered to the molded container and not peeled off.
Δ: Adhered to the molded container, but peeled off.
x: Peeling off from the molded container.

(11) Water resistance and easy adhesion test (6) The sample obtained in the test was immersed in room temperature tap water for 7 days, and the adhesion to the molded body was judged according to the following criteria.
◯: Adhered to the molded container and not peeled off.
Δ: Adhered to the molded container, but peeled off.
x: Peeling off from the molded container.

(12) Mold whitening test A SUS304 metal plate on the easy-adhesion layer side of an easy-adhesion film for in-mold molding is heated at 100°C using a hot plate TH-450 manufactured by Toyo Seisakusho Co., Ltd., and a load of 0.15 kg/cm ² is applied. was treated for 1 minute. After that, peeling was performed, and whitening stains on the SUS304 metal surface were visually observed and judged according to the following criteria.
◯: No whitening stain is observed on the surface of the SUS304 metal plate.
x: Whitening stains are observed on the surface of the SUS304 metal plate.

(Cationic antistatic agent A-1)
116 g of N,N-dimethyl-1,3-propanediamine and 285 g of stearic acid having 17 carbon atoms were subjected to an esterification reaction at 100° C. under a nitrogen atmosphere for 10 hours, and tetrahydrofuran was added as a quaternization solvent to obtain the target amine. A specified amount of dimethyl sulfate was added to the solution, and the mixture was reacted at 70° C. for about 10 hours. After the reaction, the solvent is distilled off under reduced pressure, and isopropanol is added to adjust the solid content to a desired concentration, thereby obtaining an isopropanol solution of the cationic antistatic agent (A-1) having a quaternary ammonium ethosulfate salt. rice field.

(Cationic antistatic agent A-2)
Using 89 g of dimethylaminoethanol and 228 g of myristic acid having 14 carbon atoms, A-1 was treated in the same manner as above to obtain a cationic antistatic agent (A-2) solution containing a quaternary ammonium ethosulfate salt. .

(Cationic antistatic agent A-3)
Using 89 g of dimethylaminoethanol and 354 g of tricosylic acid having 23 carbon atoms, an esterification reaction is performed at 200°C for 10 hours under a nitrogen atmosphere, tetrahydrofuran is added as a quaternization solvent, and a specified amount of dimethyl sulfate is added to the target amine at 70°C. , and reacted for about 10 hours. In addition, the same treatment as A-1 was performed to obtain an isopropanol solution of cationic antistatic agent (A-3) having a quaternary ammonium ethosulfate salt.

(Anionic antistatic agent A-4)
Dodecylbenzenesulfonic acid sodium salt (TB702 manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) was used.

(Quaternary cationic chlorine-based antistatic agent A-5)
Lauryltrimethylammonium chloride (Cathiogen (registered trademark) TML manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used.

(Polymerization of urethane resin B-1 having a polycarbonate structure)
22 parts by weight of 4,4-dicyclohexylmethane diisocyanate and 20 parts by weight of polyethylene glycol monomethyl ether having a number average molecular weight of 700 were added to a four-necked flask equipped with a stirrer, a Dimroth condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer. , 53 parts by weight of polyhexamethylene carbonate diol having a number average molecular weight of 2,100, 5 parts by weight of neopentyl glycol, and 84.00 parts by weight of acetone as a solvent were added and stirred at 75° C. for 3 hours under a nitrogen atmosphere to form a reaction solution. It was confirmed that the predetermined amine equivalent weight was reached. Next, 16 parts by mass of a polyisocyanate compound (manufactured by Asahi Kasei Chemicals, Duranate TPA, trifunctional) having an isocyanurate structure made from hexamethylene diisocyanate is added and stirred for 1 hour at 75° C. in a nitrogen atmosphere to form a reaction solution. reached the desired amine equivalent weight. After that, the temperature of the reaction solution was lowered to 50° C., and 7 parts by mass of methyl ethyl ketoxime was added dropwise. After cooling the reaction solution to 40° C., a polyurethane prepolymer solution was obtained. Next, 450 g of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring, adjusted to 25° C., and while stirring and mixing at 2000 min ⁻¹ , the polyurethane prepolymer solution was added and dispersed in water. . After that, acetone and part of the water were removed under reduced pressure to prepare a solution of water-dispersible urethane resin (B-1) having a solid content of 35% by mass.

(Polymerization of Urethane Resin B-2 Having a Polycarbonate Structure)
25 parts by mass of 4,4-dicyclohexylmethane diisocyanate, 5 parts by mass of dimethylolpropanoic acid, and a number average molecular weight of 2,600 were added to a four-necked flask equipped with a stirrer, a Dimroth condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer. 52 parts by mass of polyhexamethylene carbonate diol, 6 parts by mass of neopentyl glycol, and 84.00 parts by mass of acetone as a solvent are added and stirred at 75 ° C. for 3 hours under a nitrogen atmosphere, and the reaction solution reaches a predetermined amine equivalent weight. confirmed that it has been reached. Next, 18 parts by mass of a polyisocyanate compound (manufactured by Asahi Kasei Chemicals, Duranate TPA, trifunctional) having an isocyanurate structure made from hexamethylene diisocyanate is added, and the mixture is stirred for 1 hour at 75° C. under a nitrogen atmosphere. reached the desired amine equivalent weight. After that, the temperature of the reaction liquid was lowered to 50° C., and 8 parts by mass of methyl ethyl ketoxime was added dropwise. After cooling the reaction solution to 40° C., 5.17 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 g of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring, adjusted to 25° C., and while stirring and mixing at 2000 min ⁻¹ , the polyurethane prepolymer solution was added and dispersed in water. . After that, acetone and part of the water were removed under reduced pressure to prepare a solution of water-dispersible urethane resin (B-2) having a solid content of 35% by mass.

(Polymerization of urethane resin B-3 containing no polycarbonate polyol component)
75 parts by mass of a polyester polyol having a molecular weight of 5000, composed of terephthalic acid, isophthalic acid, ethylene glycol, and neopentyl glycol, 30 parts by mass of hydrogenated m-xylylenediisocyanate, 7 parts by mass of ethylene glycol, and 6 parts by mass of dimethylolpropionic acid Parts by mass and 84.00 parts by mass of acetone as a solvent were added and stirred at 75° C. for 3 hours under a nitrogen atmosphere, and it was confirmed that the reaction liquid reached a predetermined amine equivalent weight. After cooling the reaction solution to 40° C., 5.17 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 g of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring, the temperature was adjusted to 25° C., and the polyurethane prepolymer solution was added while stirring and mixing at 2000 min ⁻¹ . Water dispersed. After that, acetone and part of the water were removed under reduced pressure to prepare a solution of water-dispersible urethane resin (B-3) having a solid content of 35% by mass.

(Preparation of polyurethane-blocked isocyanate (B-4) having a polyester structure)
33.6 parts by mass of hexamethylene diisocyanate was added to 200 parts by mass of a polyester (molecular weight: 2000) of an adduct of 2 mol of ethylene oxide of bisphenol A and maleic acid, and the reaction was carried out at 100° C. for 2 hours. Next, the temperature of the system is once lowered to 50° C., 73 parts by mass of a 30% aqueous sodium bisulfite solution is added, and the mixture is stirred at 45° C. for 60 minutes, diluted with 718 parts by mass of water, and blocked polyisocyanate (B-4 ) with a solid content of 20.0% by mass was obtained. The number of functional groups of the blocked isocyanate crosslinking agent is 2, and the NCO equivalent is 1,300.

(Polymerization of blocked isocyanate cross-linking agent C-1)
A polyisocyanate compound having an isocyanurate structure (manufactured by Asahi Kasei Chemicals, Duranate TPA) made from hexamethylene diisocyanate was placed in a flask equipped with a stirrer, thermometer, and reflux condenser, 66.04 parts by mass, and 17.50 parts by mass of N-methylpyrrolidone. 95 parts by weight of 3,5-dimethylpyrazole (dissociation temperature: 120° C., boiling point: 218° C.) was added dropwise to the parts by weight, and the mixture was maintained at 70° C. for 1 hour in a nitrogen atmosphere. After that, 30 parts by mass of dimethylolpropanoic acid was added dropwise. After measuring the infrared spectrum of the reaction solution and confirming that the absorption of the isocyanate group has disappeared, 5.59 parts by mass of N,N-dimethylethanolamine and 132.5 parts by mass of water are added to block polyisocyanate (C- An aqueous dispersion of 1) having a solid content of 40% by mass was obtained. The number of functional groups of the blocked isocyanate crosslinking agent is 4, and the NCO equivalent is 280.

(Polymerization of blocked isocyanate cross-linking agent C-2)
A flask equipped with a stirrer, a thermometer, and a reflux condenser is charged with 100 parts by mass of a polyisocyanate compound having an isocyanurate structure (Duranate TPA, manufactured by Asahi Kasei Chemicals Co., Ltd.) made from hexamethylene diisocyanate, 55 parts by mass of propylene glycol monomethyl ether acetate, and polyethylene. 30 parts by mass of glycol monomethyl ether (average molecular weight: 750) was charged, and the mixture was held at 70°C for 4 hours under a nitrogen atmosphere. After that, the temperature of the reaction solution was lowered to 50° C., and 47 parts by mass of methyl ethyl ketoxime was added dropwise. The infrared spectrum of the reaction solution was measured to confirm that the absorption of the isocyanate group had disappeared, and 210 parts by mass of water was added to obtain an aqueous dispersion of the oxime-blocked isocyanate crosslinking agent (C-2) with a solid content of 40% by mass. rice field. The number of functional groups of the blocked isocyanate crosslinking agent is 3, and the NCO equivalent is 170.

(Polymerization of polyester resin D-1)
194.2 parts by weight of dimethyl terephthalate, 184.5 parts by weight of dimethyl isophthalate, 14.8 parts by weight of dimethyl-5-sodium sulfoisophthalate were added to a stainless steel autoclave equipped with an agitator, thermometer, and partial reflux condenser. , 185 parts by mass of neopentyl glycol, 188 parts by mass of ethylene glycol, and 0.2 parts by mass of tetra-n-butyl titanate were charged, and transesterification was carried out at a temperature of 160° C. to 220° C. for 4 hours. Then, the temperature was raised to 255° C., the pressure of the reaction system was gradually reduced, and the reaction was allowed to proceed under a reduced pressure of 30 Pa for 1 hour and 30 minutes to obtain a copolymer polyester resin (D-1). The resulting copolymer polyester resin (D-1) was pale yellow and transparent. The reduced viscosity of the copolymer polyester resin (D-1) was measured to be 0.40 dl/g. The glass transition temperature by DSC was 65°C.

(Adjustment of polyester water dispersion Dw-1)
25 parts by mass of copolymer polyester resin (D-1) and 10 parts by mass of ethylene glycol n-butyl ether were placed in a reactor equipped with a stirrer, a thermometer and a reflux device, heated at 110° C. and stirred to dissolve the resin. After the resin was completely dissolved, 65 parts by mass of water was slowly added to the polyester solution with stirring. After the addition, the liquid was cooled to room temperature while stirring to prepare a milky white polyester water dispersion (Dw-1) having a solid content of 25% by mass.

(Polymerization of polyester resin D-2)
194.2 parts by weight of dimethyl terephthalate, 184.5 parts by weight of dimethyl isophthalate, 14.8 parts by weight of dimethyl-5-sodium sulfoisophthalate were added to a stainless steel autoclave equipped with an agitator, thermometer, and partial reflux condenser. , 233.5 parts by mass of diethylene glycol, 136.6 parts by mass of ethylene glycol, and 0.2 parts by mass of tetra-n-butyl titanate were charged, and transesterification was carried out at a temperature of 160° C. to 220° C. over 4 hours. Then, the temperature was raised to 255° C., the pressure of the reaction system was gradually reduced, and the reaction was allowed to proceed under a reduced pressure of 30 Pa for 1 hour and 30 minutes to obtain a copolymerized polyester resin (D-2). The resulting copolymer polyester resin (D-2) was pale yellow and transparent. When the reduced viscosity of the copolymer polyester resin (D-2) was measured, it was 0.70 dl/g. The glass transition temperature by DSC was 40°C.

(Adjustment of polyester water dispersion Dw-2)
25 parts by mass of copolymer polyester resin (D-2) and 10 parts by mass of ethylene glycol n-butyl ether were placed in a reactor equipped with a stirrer, thermometer and reflux device, and the mixture was heated at 110° C. and stirred to dissolve the resin. After the resin was completely dissolved, 65 parts by mass of water was slowly added to the polyester solution with stirring. After the addition, the liquid was cooled to room temperature while stirring to prepare a milky white polyester water dispersion (Dw-2) having a solid content of 25% by mass.

(Example 1)
The solid content in the coating liquid of the compound constituting the coating layer is as follows.
The total solid content contained in the coating layer is defined as 100% by mass.
· Cationic antistatic agent A-1: 6.2% by mass
・ Urethane resin B-1 having a polycarbonate structure: 22.8% by mass
・Blocked isocyanate cross-linking agent C-1: 22.8% by mass
・Polyester resin D-1: 45.4% by mass
・Silicone-based surfactant: 0.4% by mass
・pH adjuster (sodium hydrogen carbonate): 2.4% by mass
The solid content mass ratio of urethane resin (B-1)/crosslinking agent (C-1)/polyester resin (D-1) is 25/25/50.

(1) Production of white void-containing polyester film (F-1)
(Preparation of master pellet)
60% by mass of polymethylpentene resin (DX820, manufactured by Mitsui Chemicals, Inc.) with a melt viscosity (η) of 1,300 poise, and 20 mass of polystyrene resin (G797N, manufactured by Nippon Polystyrene Co., Ltd.) with a melt viscosity (η) of 3,900 poise % and 20% by mass of a polypropylene resin (manufactured by Grand Polymer Co., Ltd., J104WC) having a melt viscosity of 2,000 poise were supplied to a vented twin-screw extruder temperature-controlled at 285° C. and preliminarily kneaded. . This molten resin was continuously supplied to a vent-type single-screw kneader, kneaded and extruded, and the resulting strand was cooled and cut to prepare cavity-generating agent master pellets (M1).

In addition, 50% by mass of polyethylene terephthalate resin having an intrinsic viscosity of 0.62 dl/g produced by a known method and 50% by mass of anatase titanium dioxide particles having an average particle size of 0.3 μm (TA-300, manufactured by Fuji Titanium Co., Ltd.) are mixed. The mixture was supplied to a vented twin-screw extruder and preliminarily kneaded. This molten resin was continuously supplied to a vented single-screw kneader, kneaded and extruded. The resulting strand was cooled and cut to prepare titanium dioxide-containing master pellets (M2).

(Preparation of film raw material)
81% by mass of the polyethylene terephthalate resin having an intrinsic viscosity of 0.62 dl / g vacuum dried at 140 ° C. for 8 hours and 9% by mass of the master pellet (M1) vacuum dried at 90 ° C. for 4 hours, and the above 10% by mass of the master pellets (M2) were pellet-mixed to obtain a film raw material (G1).

(Production of unstretched film)
70% by mass of the same polyethylene terephthalate resin as used in the film raw material (G1) and 30% by mass of the master pellets (M2) are mixed in an extruder for layer B in which the temperature of the film raw material (G1) is controlled at 285 ° C. These were separately supplied to an A-layer extruder whose temperature was controlled at 290°C. The molten resin discharged from the extruder for layer B is led through an orifice, and the resin discharged from the extruder for layer A is led to a feed book through a static mixer, and a layer (B layer) composed of the film raw material (G1). and polyethylene terephthalate resin and master pellets (M2) were laminated in the order of A layer/B layer/A layer.

This molten resin was co-extruded in a sheet form from a T-die onto a cooling roll whose temperature was adjusted to 25° C., and adhered and solidified by an electrostatic application method to prepare an unstretched film having a thickness of 510 μm. The discharge rate of each extruder was adjusted so that the thickness ratio of each layer was 1:8:1. At this time, the molten resin stayed in the melt line for about 12 minutes, and the shear rate received from the T-die was about 150/sec.

(Production of biaxially stretched film)
The resulting unstretched film was uniformly heated to 65°C using a heating roll, and was passed between two pairs of nip rolls with different peripheral speeds (low speed roll: 2 m/min, high speed roll: 6.8 m/min) at 3.4 It was longitudinally stretched twice. At this time, as an auxiliary heating device for the film, an infrared heater (rated output: 20 W / cm) equipped with a gold reflective film in the middle of the nip roll was placed on both sides of the film at a position 1 cm from the film surface and heated. . Both sides of the uniaxially stretched film thus obtained were coated using the above coating composition by the reverse gravure coating method so that the WET coating amount was 7 g / m ² each, then led to a tenter and dried. While heating to 150 ° C., laterally stretching 3.7 times, fixing the width, performing heat treatment at 220 ° C. for 5 seconds, and further relaxing 4% in the width direction at 200 ° C., resulting in an in-mold thickness of 50 µm. An easy-adhesive polyester film for labels was obtained. This film has excellent whiteness, and has an apparent density of 1.10 g/cm ³ and an optical density of 0.8 due to the appearance of voids. No. ² easy-adhesive polyester film for in-mold label was obtained. Table 1 shows the evaluation results.

(Examples 2 to 26)
An easy-adhesive polyester film for an in-mold label was obtained in the same manner as in Example 1, except that the coating layer structure was changed to that shown in Table 1.

(Example 27)
The solid content in the coating liquid of the compound constituting the coating layer is as follows.
The total solid content contained in the coating layer is defined as 100% by mass.
・ Colloidal silica particles (E-1) (average particle size: 450 nm): 48.8% by mass
· Cationic antistatic agent A-1: 2.1% by mass
・ Urethane resin B-1 having a polycarbonate structure: 12.2% by mass
・Blocked isocyanate cross-linking agent C-1: 12.2% by mass
・Polyester resin D-1: 24.4% by mass
・Silicone-based surfactant: 0.1% by mass
・pH adjuster (sodium hydrogen carbonate): 0.2% by mass
The mass ratio of urethane resin (B-1)/crosslinking agent (C-1)/polyester resin (D-1) is 25/25/50/.
In the same manner as in Example 1, except that the composition of the coating layer was changed to 10 g / m ² on each of the WET coating amounts on both sides, the easily adhesive coating layer thickness after drying on both sides was 0.55 g / m No. ² easy-adhesive polyester film for in-mold label was obtained. A coating layer having a gloss value of 9.0 in regular reflection at 60 degrees on the surface of the coating layer and having a matte appearance was obtained.

(Example 28)
The solid content in the coating liquid of the compound constituting the coating layer is as follows.
The total solid content contained in the coating layer is defined as 100% by mass.
・Benzoquanamine particles (E-2) (average particle size: 1.2 μm): 38.3% by mass
· Cationic antistatic agent A-1: 2.1% by mass
・ Urethane resin B-1 having a polycarbonate structure: 14.8% by mass
・Blocked isocyanate cross-linking agent C-1: 14.8% by mass
・Polyester resin D-1: 29.6% by mass
・Silicone-based surfactant: 0.1% by mass
・pH adjuster (sodium hydrogen carbonate): 0.3% by mass
The mass ratio of urethane resin (B-1)/crosslinking agent (C-1)/polyester resin (D-1) is 25/25/50/.
In-mold with a coating layer thickness of 0.93 g / m ² after drying on both sides in the same manner as in Example 1 except that the coating layer was configured as described above and the WET coating amount on both sides was changed to 12 g / m ² An easy-adhesive polyester film for labels was obtained. A coating layer having a gloss value of 14.0 in regular reflection at 60 degrees on the surface of the coating layer and having a matte appearance was obtained.

(Example 29)
An easy-adhesive polyester film for in-mold labels was obtained in the same manner as in Example 27, except that the coating layer structure was changed to that shown in Table 1.

(Example 30)
An easy-adhesive polyester film for in-mold labels was obtained in the same manner as in Example 28, except that the coating layer structure was changed to that shown in Table 1.

(Example 31)
The solid content in the coating liquid of the compound constituting the coating layer is as follows.
The total solid content contained in the coating layer is defined as 100% by mass.
・ Colloidal silica particles E-3 (average particle diameter: 100 nm): 1.6% by mass
· Cationic antistatic agent A-1: 6.2% by mass
・ Urethane resin B-1 having a polycarbonate structure: 25.3% by mass
・Blocked isocyanate cross-linking agent C-2: 10.8% by mass
・Polyester resin D-1: 54.2% by mass
・Silicone-based surfactant: 0.4% by mass
・pH adjuster: 1.6% by mass (sodium hydrogen carbonate)
The mass ratio of urethane resin (B-1)/crosslinking agent (C-2)/polyester resin (D-1) is 28/12/60/.

(2) Production of Polyester Film Substantially Free of Particles (F-2)
PET resin pellets having an intrinsic viscosity (solvent: phenol/tetrachloroethane = 60/40) of 0.62 dl/g and containing substantially no particles were used as the film material polymer, and were extruded at 135°C for 6 hours under a reduced pressure of 133 Pa. Time dried. After that, it was supplied to an extruder, melt-extruded into a sheet at about 280° C., and rapidly cooled and solidified on a rotating cooling metal roll whose surface temperature was maintained at 20° C. to obtain an unstretched PET sheet.
This unstretched PET sheet was heated to 100° C. by a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction by a roll group with a peripheral speed difference to obtain a uniaxially stretched PET film. Next, using the coating liquid composition based on the solid content, both sides of the uniaxially stretched PET film are coated by a reverse gravure coating method so that the wet coating amount is 7 g / m ² on each side. While drying, the film was heated to 150°C, laterally stretched 3.7 times, fixed in width, heat-treated at 220°C for 5 seconds, and further relaxed at 200°C in the width direction by 4%, resulting in a film thickness of 50 µm. An easy-adhesive polyester film for in-mold labels was obtained. The film has excellent transparency, an apparent specific gravity of 1.42 g/cm ³ , a total light transmittance of 91%, and a coating layer thickness of 0.12 g/m ² on both sides after drying. An easily adhesive polyester film was obtained.

(Comparative Examples 1 to 7)
A polyester film was obtained in the same manner as in Example 1, except that the composition of the coating layers shown in Table 1 was changed.

According to the easy-adhesive polyester film for in-mold labels of the present invention, it is possible to provide labels, stickers, etc., which are excellent in mass productivity. It is possible to provide an easy-adhesive polyester film for in-mold labels with little change in the surface quality of the adhesive layer.

Claims (5)

Having an easy-adhesion layer on at least one surface of the polyester film,
The easy adhesion layer is formed by curing a composition containing an ion-conducting antistatic agent, a polyester resin, and a polycarbonate urethane resin, and the surface specific resistance of the easy adhesion layer surface is 1.0×10 ¹³ Ω/sq or less. And, after contacting another polyester film to the surface of the easy adhesion layer and holding it at 50 ° C. under a pressure of 1 kg / cm ² for 3 days, the other polyester film that was in contact with the surface of the easy adhesion layer An easy-adhesive polyester film for an in-mold label, the surface of which has a surface specific resistance of 1.0×10 ¹⁴ Ω/sq or more. Another polyester film is brought into contact with the surface of the easy-adhesion layer, and the surface resistivity of the easy-adhesion layer surface is 1.0 after holding for 3 days at 60° C. and 90% temperature and humidity under a pressure of 1 kg/cm ² . x 10 ¹³ Ω/sq or less, and another polyester film is brought into contact with the surface of the easy-adhesion layer, and the easy-adhesion layer is held at 60°C and 90% temperature and humidity under a pressure of 1 kg/cm ² for 2 days. 2. The easy-adhesive polyester film for in-mold labels according to claim 1, wherein the other polyester film in contact with the surface has a surface resistivity of 1.0*10< ¹³ > [Omega]/sq or more. The easy adhesion for in-mold labels according to claim 1 or 2, wherein the solid content of the ion conductive antistatic agent is 1 to 8% by mass when the total solid content contained in the composition is 100% by mass. polyester film. The easy-adhesive polyester film for in-mold labels according to any one of claims 1 to 3, which contains 0 to 50% by mass of a cross-linking agent as a solid content when the total solid content contained in the composition is 100% by mass. . The easy-adhesive polyester film for an in-mold label according to any one of claims 1 to 4, wherein the easy-adhesion layer is heat-sealed and adhered to a blow-molded container containing a thermoplastic resin.