JP2022070978A - Laminated white polyester film and recorded material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated white polyester film with a strong functional layer, which can be reused when used as a recording material, which is an information printing medium, and can suitably transfer an image such as a toner image by a method such as an electrophotographic and thermal transfer method that transfers a toner image to the recording material, and can easily peel off and remove the toner image etc., after being used as a material to be recorded.

SOLUTION: There is provided a laminated white polyester film having a functional layer on at least one side of a polyester film containing polyester as a main component resin and containing a polymer incompatible with the polyester, the functional layer containing a mold release agent composed of a long-chain alkyl group-containing compound, a cross-linking agent, and an antistatic agent, in which an amount of change in a peeling force, which is a difference between the peeling force after three peeling operations and an initial peeling force, is 950 mN/cm or less.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a laminated white polyester film. More specifically, the present invention relates to a plastic sheet suitable as a recording material, which is an information printing medium that replaces paper such as copy paper.

Currently, with the increasing performance of copiers and printing printers, these devices are used for various purposes and forms such as printing and copying documents, printing photographs and videos, and issuing forms and slips. It is used for the issuance of. As a result, the consumption of copy paper and printer paper in businesses and homes is increasing.

Since mass consumption of paper including copy paper and printer paper is not desirable from the viewpoint of suppressing deforestation, recycled paper that has been collected, separated into recycled pulp at a paper mill, and recycled has been used. ..
Recycled paper is used paper recovered from its main raw materials, but in order to make recycled paper from the recovered used paper, a certain amount of new wood resources are also required, so it is tentatively recycled paper. Even if the utilization rate of paper increases, wood resources will still be consumed, and the use of recycled paper will not be a drastic solution to protect the forest environment. In addition, since the recycling process also requires energy, there is a problem from the viewpoint of energy saving.
In addition, the quality of recycled paper is still inferior to that of high-quality paper, and when copying paper made of recycled paper is used, the whiteness of the paper is reduced and the color is grayish, so the degree of color development when printing is performed. There is a tendency for the image quality to deteriorate.
In addition, recycled paper is expensive to manufacture and tends to be more expensive than woodfree paper.
Due to these various problems, the actual situation is that the use as a substitute for high-quality paper has not been established.

Instead of such recycled paper, there has been proposed a paper that can reuse the used paper by peeling and removing the image formed on the surface of the paper by an electrophotographic method such as a copying machine. For example, based on paper mainly composed of cellulose fibers, a layer containing a polymer selected from polyvinyl alcohol, starch, carboxymethyl cellulose, polyvinyl acetate, and acrylic resin is provided on the surface of the base on which an image is recorded, and the polymer is provided. A reusable recorded material in which a layer containing a linear or branched compound having an alkyl group or an alkenyl group and having a toner-repellent property is provided on the containing layer is disclosed (see, for example, Patent Document 1).
However, since the recorded material has a thin polymer layer in order to reduce the cost of the polymer layer and requires paper for the base, it does not mean that wood resources are not completely used, so that the forest environment is improved. It is not a solution to protect. Further, as long as paper is used, the recorded image is impregnated inside the fibers of the paper, so that the peeling removal performance is insufficient.

Therefore, there is a study of synthetic paper made of plastic as a material completely replaced with paper. For example, synthetic paper made of polypropylene is used for daily necessities (see, for example, Patent Document 2).

However, the synthetic paper described in Patent Document 2 is sensitive to heat, and when used in a copying machine or printer that fixes toner at a relatively high temperature, the synthetic paper melts in the copying machine, causing wrinkles and causing a paper jam. Was likely to occur.

Japanese Unexamined Patent Publication No. 2005-234162 Japanese Unexamined Patent Publication No. 10-204196

The present invention has been made in view of the above circumstances, and the problem to be solved thereof is that it can be used as a recording material which is an information printing medium instead of paper such as copy paper, and is extremely excellent in cost and strong. It is an object of the present invention to provide a laminated white polyester film having a functional layer.

The gist of the present invention is characterized by having a functional layer which is a cured product formed from a composition containing 1% by weight or more of a cross-linking agent on at least one side of a polyester film containing a polymer incompatible with polyester. It exists in the laminated white polyester film.

The laminated white polyester film of the present invention is used as a recording material which is an information printing medium that replaces paper such as copying paper by containing a polymer incompatible with the polyester in addition to the polyester in the polyester film as a base material. It is a plastic film that can be used and is extremely cost effective. Further, the laminated white polyester film of the present invention can suitably transfer a toner image. That is, the toner image can be suitably transferred by a method such as an electrophotographic method or a thermal transfer method in which the toner image is transferred to the recording material. Further, after being used as a recording material, characters and images due to an image forming substance such as toner formed on the surface can be easily peeled off and removed.
Further, by having a functional layer containing a cross-linking agent on at least one side of the polyester film, it can be made into a strong functional layer, and it can be used as a recording material for copying paper or printer paper to prevent scraping and scratches in the transport process in the copying machine. By preventing sticking and reducing erosion by image-forming substances, it is possible to record accurately without bleeding of characters and images. Further, since various functions of the functional layer can be retained, it can be reused as a recorded material after removing characters and images.

Hereinafter, the present invention will be described in more detail.

<Laminated white polyester film>
As an example of a mode for carrying out the present invention, a laminated white polyester film having a functional layer containing 1% by weight or more of a cross-linking agent on at least one side of a polyester film containing a polymer incompatible with polyester (“this laminated”). "White polyester film") will be described.

<Polyester film>
The polyester film as the base material of the laminated white polyester film preferably includes a polyester resin layer containing at least polyester as a main component resin and a polymer incompatible with polyester.
Here, the "main component resin" means a resin having the highest content ratio among the resin components constituting the polyester resin layer. It can be assumed that the main component resin accounts for 30% by weight or more, particularly 50% by weight or more, and 80% by weight or more (including 100% by weight) among the resin components constituting the polyester resin layer.

The polyester film may be a single layer composed of the polyester resin layer, or may be a multi-layer having two layers, three layers, four layers or more provided with the polyester resin layer, and is particularly limited. is not. That is, when the polyester film is a single layer, the polyester film means the polyester resin layer itself. When the polyester film has two or more layers, all the layers may be polyester resin layers, or one or more layers may be resin layers other than polyester. In particular, it is preferable that all the layers are polyester resin layers.
Above all, the polyester film is preferably laminated in two or more layers, and a three-layer structure (surface layer / intermediate layer / surface layer) composed of both surface layers and an intermediate layer is more preferable.
In addition, the case where the multilayer structure is two layers means that it is composed of two surface layers, and specifically, the composition of the polyester constituting each layer and the composition of the contained particles and the like are different. Examples thereof include cases where the layers are formed.

(polyester)
The polyester constituting the polyester film as a base material refers to a polyester obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol.
Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid and the like, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, trimethylene glycol, tetramethylene glycol and neopentyl glycol, 1. , 4-Cyclohexanedimethanol and the like.

Typical polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), polybutylene terephthalate and the like. The polyester may be a non-copolymerizable homopolymer, and 20 mol% or less of the dicarboxylic acid component is a dicarboxylic acid component other than the main component, and / or 20 mol% or less of the diol component is other than the main component. It may be a copolymerized polyester which is a diol component. Further, a mixture thereof may be used, but in order to reduce mechanical and thermal damage in the transport and printing processes in the copying machine, homopolyester is preferable, and PET and PEN are most suitable. Further, when considering recycling, it is preferable that the mechanical and thermal properties are more stable. For example, in the case of PET, the content of monomer components other than terephthalic acid and ethylene glycol is small. The amount thereof is preferably in the range of preferably 10 mol% or less, more preferably 5 mol% or less, still more preferably 3 mol% or less as a ratio to the whole polyester. Examples of the monomer component other than terephthalic acid and ethylene glycol mentioned here are the above-mentioned dicarboxylic acid and aliphatic glycol, and examples thereof include diethylene glycol, trimethylene glycol, and isophthalic acid.

Polyester can be obtained by a conventionally known method, for example, a method of directly obtaining polyester by a reaction of a dicarboxylic acid and a diol, or a method of reacting a lower alkyl ester of a dicarboxylic acid with a diol with a conventionally known ester exchange catalyst, and then the presence of a polymerization catalyst. It can be obtained by a method of carrying out a polymerization reaction below. As the polymerization catalyst, known catalysts such as antimony compounds, germanium compounds, titanium compounds and aluminum compounds can be used.

(Polymer incompatible with polyester)
By containing a polymer incompatible with polyester in the polyester film, innumerable ultrafine cavities can be contained in the polyester film stretched at least in the uniaxial direction. The ultrafine cavities allow the polyester film to scatter light, resulting in white opacity and reducing the apparent density of the polyester film. Not only that, it has also been found that an image-forming substance containing a thermoplastic resin such as toner printed on the surface of a polyester film can be easily peeled off and removed.
The surface layer containing the polymer incompatible with the polyester may be on both sides or only one side of the polyester film, but is preferably contained in the surface layers on both sides. Above all, by containing a polymer incompatible with polyester in the surface layer of the polyester film, when used as a recording material for copy paper or printer paper, a thermoplastic resin such as toner printed on the surface of the laminated white polyester film can be used. The contained image-forming substance can be easily fixed and easily peeled off and removed.
That is, by having fine cavities in the surface layer of the polyester film or by roughening the surface, it is possible to exhibit an anchor effect for satisfactorily fixing the image forming substance. Further, by containing a polymer incompatible with polyester in the surface layer, it is possible to adjust the fixing force of the image forming substance, so that it can be easily peeled off. Surprisingly, such an effect can be exhibited in the same manner or even more remarkably even when the functional layer described later is provided on the surface of the polyester film.
Further, in order to ensure sufficient hiding power and weight reduction, a polymer incompatible with polyester may be contained in the intermediate layer, if necessary.

When the polyester film has a multi-layer structure, the polymer incompatible with polyester may be contained in all layers of the polyester film, or may be selectively contained in a specific layer. Specifically, the polymer incompatible with polyester may be contained in at least one surface layer of the polyester film, or may be contained in an intermediate layer.

As the polymer incompatible with polyester, conventionally known polymers can be used, and examples thereof include polyolefins, polystyrenes, polyacrylic acids, polycarbonates and the like. Among them, polyolefins and polystyrenes are preferable, and polyolefins are particularly preferable. Further, among the polyolefins, polypropylene, polyethylene, poly-4-methylpentene-1, amorphous polyolefin and the like can be mentioned, and among them, polypropylene is more preferable in consideration of the easiness of forming cavities and forming a film. Further, as the polymer incompatible with polyester, a polyester different from the main component resin constituting the polyester film can also be used. In the present invention, the organic particles described later correspond to particles other than metal compound particles.

In the polyester resin layer, the content ratio of the polymer incompatible with the polyester with respect to the polyester is 1 part by weight or more or 70 parts by weight or less with respect to 100 parts by weight of the polyester. It is preferably contained in a proportion of 2 parts by weight or more or 50 parts by weight or less, more preferably 3 parts by weight or more or 40 parts by weight or less, and 5 parts by weight or more or 35 parts by weight or less. It is particularly preferable to contain the content in the proportion of.

When polypropylene is used as a polymer incompatible with polyester, the melt flow index of polypropylene under the conditions of a temperature of 230 ° C. and a load of 2.16 kg (21.2 N) is usually 0.5 ml / 10 minutes or more as a lower limit. It is preferably 1 ml / 10 minutes or more, more preferably 3 ml / 10 minutes or more, and further preferably 5 ml / 10 minutes or more. In the case of the above range, a sufficient cavity size can be generated, and it is possible to easily avoid breakage during stretching.
On the other hand, the upper limit is usually 50 ml / 10 minutes or less, preferably 40 ml / 10 minutes or less, more preferably 30 ml / 10 minutes or less, still more preferably 25 ml / 10 minutes or less. In the above range, it is possible to avoid the clip coming off during lateral stretching, and it is possible to maintain productivity.

The lower limit of the content of the polymer incompatible with polyester in the polyester film is usually 1% by weight or more, preferably 2% by weight or more, more preferably 3% by weight in the polyester layer containing the polymer incompatible with polyester. % Or more, more preferably 5% by weight or more, and particularly preferably 8% by weight or more. By using the film within the above range, the amount of fine cavities formed in the film becomes sufficient, the concealing property of the film is improved, and the effect of reducing the apparent density is sufficient. In addition, the slipperiness of the film and the writability of pencils and the like are improved, which is advantageous for print transportability. Further, on the surface of the film, characters and images due to the printed image-forming substance are easily adhered and peeled off, so that the film can be repeatedly used as a recording material for copy paper or printer paper.
On the other hand, the upper limit of the content of the polymer incompatible with polyester in the polyester film is usually 70% by weight or less, preferably 50% by weight or less, more preferably 50% by weight or less in the polyester layer containing the polymer incompatible with polyester. It is 40% by weight or less, more preferably 35% by weight or less, particularly preferably 30% by weight or less, and most preferably 25% by weight or less. By using it in this range, the amount of cavities generated is not too large, and it tends to be easy to suppress breakage during stretching.
The content of the incompatible polymer can be measured by analytical means such as NMR and IR.
Further, when the polyester film has a multi-layer structure, the above-mentioned content means the content in a specific layer, specifically, when it means the content in at least one surface layer of the polyester film, or when it means the content in at least one surface layer of the polyester film. It may mean the content in the intermediate layer.

When the polyester film has three or more layers, the intermediate layer has a surplus portion generated during film production, for example, an end portion (ear portion), a master roll end portion (ear portion), and a master roll surplus portion (lower winding). Part) and other recycled products may be blended within a range that does not impair the gist of the present invention. By including recycled products, it has the effects of cost reduction and environmental load reduction.
The content of the recycled product in the intermediate layer is preferably 95% by weight or less, more preferably 85% by weight or less, in terms of film formation stability due to the decrease in intrinsic viscosity, in addition to the color tone regulation. It is more preferably 70% by weight or less, particularly preferably 60% by weight or less, and most preferably 40% by weight or less. The lower limit of the content of the recycled product in the intermediate layer is not limited and may be 0% by weight, but from the viewpoint of cost reduction, it is preferably 1% by weight or more, more preferably 3% by weight or more, still more preferably 5% by weight. That is all.

(Metal compound particles)
Whether the polyester film has a single layer or two or more layers, it is possible to contain metal compound particles for the purpose of further improving concealment and whiteness.
When the polyester film has two or more layers, it is preferable that the metal compound particles are also contained in the polyester resin layer. When the polyester film has three or more layers, it may be a surface layer or an intermediate layer, but it is contained in the surface layer in order to effectively improve the hiding power and the whiteness. It is preferable to do so.

The metal compound particles used in the polyester film tend to compensate for the white opacity caused by the light scattering effect caused by the fine cavities caused by blending the incompatible polymer, so that higher concealment and whiteness can be obtained. There is a tendency.
Examples of the metal compound particles used include known titanium oxide, calcium carbonate, barium sulfate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, zirconium oxide and the like, and among them, titanium oxide. , Calcium carbonate, barium sulfate and other metal compound particles, among which titanium oxide is particularly suitable from the viewpoint of hiding property and improvement of whiteness.

The lower limit of the average particle size of the metal compound particles used is usually 0.05 μm or more, preferably 0.10 μm or more, more preferably 0.20 μm or more, still more preferably 0.25 μm or more, and the upper limit is usually 0.50 μm or less. It is preferably 0.45 μm or less, more preferably 0.40 μm or less. By using metal compound particles having an average particle size in the above range, the degree of concealment when made into a film is sufficient, uniform whiteness can be obtained, and show-through is particularly improved when printed on both sides of the film. It tends to be used as a recording material for copying paper and printer paper.
The shape of the metal compound particles is not particularly limited, and may be spherical, lumpy, rod-shaped, flat, or the like. Further, the hardness, specific gravity, color and the like are not particularly limited. Two or more kinds of these particles may be used in combination as needed.

Further, the lower limit of the content of the metal compound particles is preferably 1% by weight or more, more preferably 2% by weight or more, still more preferably 3% by weight or more in the polyester film containing the metal compound particles. The upper limit is usually 30% by weight or less, preferably 20% by weight or less, more preferably 15% by weight or less, still more preferably 13% by weight or less, and particularly preferably 10% by weight or less. By setting the content of the metal compound particles within the above range, a sufficient degree of concealment can be imparted, which is also advantageous in terms of cost. It tends to be optimal for use as a material.
When the polyester film has a multi-layer structure, it means the content in a specific layer, specifically, when it means the content in at least one surface layer of the polyester film, or it means the content in the intermediate layer. May be done.

(Particles other than metal compound particles)
Further, in order to improve the handleability and slipperiness of the laminated white polyester film, particles other than the metal compound particles exemplified above may be contained in the polyester film.
Specific examples of the particles other than the metal compound particles exemplified above include silica particles and organic particles.
Specific examples of the organic particles include acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin, and benzoguanamine resin. Of these, silica particles are particularly preferable because they are likely to be effective even in a small amount.

The average particle size of the particles other than the metal compound particles exemplified above is preferably more than 0.50 μm, more preferably 1.0 μm or more, still more preferably 1.5 μm or more, and particularly preferably 2.0 μm or more. By setting the average particle size of the particles other than the metal compound particles in the above range, it tends to be possible to impart sufficient slipperiness. The upper limit of the average particle size of the particles is usually 15.0 μm or less, preferably 12.0 μm or less, more preferably 10.0 μm or less, still more preferably 8.0 μm or less. Within the above range, the surface of the film does not become too rough, the characters and images of the image-forming substance printed on the surface of the film can be easily peeled off and removed, and the film is repeatedly used as a recording material for copying paper or printer paper. It tends to be possible to use it as a printer. Further, it is not necessary to make the thickness of the surface layer extremely thick from the surface of particle shedding, and the optimum range of the thickness is wide, which is a preferable form.

The shape of the particles other than the metal compound particles exemplified above is not particularly limited, and any of spherical, lumpy, rod-shaped, flat-shaped and the like may be used. Further, the hardness, specific gravity, color and the like are not particularly limited. Two or more kinds of these particles may be used in combination as needed.

The content of particles other than the metal compound particles exemplified above cannot be unequivocally determined because it depends on the average particle size, but is usually 5% by weight or less with respect to the polyester film containing particles other than the metal compound particles. It is preferably 3% by weight or less, more preferably 2% by weight or less, still more preferably 1% by weight or less, and the lower limit of the preferable range is 0.005% by weight or more, more preferably 0.05% by weight or more, further. It is preferably 0.1% by weight or more. By using the film within the above range, the surface roughness of the film can be made appropriate, and the desired slipperiness can be achieved. In addition to imparting slipperiness, it also makes it easier to peel off and remove characters and images of image-forming substances printed on the surface of the film, making the film optimal as a recording material for repetitive copy paper and printer paper. Tend to be able to. Furthermore, as the role of particles other than the metal compound particles, there is a tendency to further improve the writability of pencils, mechanical pencils, ballpoint pens, and the like.
When the polyester film has a multi-layer structure, it means the content in a specific layer, specifically, when it means the content in at least one surface layer of the polyester film, or it means the content in the intermediate layer. May be done.

(Other ingredients)
Since the polyester film as the base material of this laminated white polyester film contains an incompatible polymer, by stretching the extruded sheet in at least one axial direction, a fine independent space (cavity) is formed inside the film. ) Can be obtained. Therefore, for example, a surfactant, a fluorescent whitening agent, or the like may be blended in order to further miniaturize the cavity or increase the hiding power and whiteness.

In addition to the above-mentioned particles and the polymer incompatible with polyester, conventionally known antioxidants, heat stabilizers, lubricants, antistatic agents, dyes, pigments and the like may be added to the polyester film, if necessary. can. Further, depending on the application, an ultraviolet absorber, particularly a benzoxazinone-based ultraviolet absorber or the like may be contained.

(In the case of multi-layer configuration)
When the polyester film as the base material of the laminated white polyester film has a multilayer structure of two or more layers, if it is two layers, any one layer is used, and if it is three or more layers, the surface layer is a metal compound particle or a metal compound particle. It is preferable that the layer contains particles other than the above.

For example, in the case of a multi-layer structure having three or more layers, if the surface layer contains the polyester and a resin incompatible with the polyester, fine cavities can be provided by stretching, so that weight reduction, concealment and concealment can be achieved. Since whitening can be realized and the surface roughness can be adjusted, the writing property can be improved, the image formed by the image forming substance or the like can be easily fixed, and the image forming substance can be peeled off after use. You can also do it. If the surface layer further contains metal compound particles, the hiding power and whiteness can be further enhanced, and further, by containing particles other than the metal compound particles, the slipperiness can be improved.

On the other hand, if the intermediate layer other than the surface layer contains the polyester, the resin incompatible with the polyester, the metal compound particles, and the particles other than the metal compound particles may be contained, if necessary. It is preferable that the content of the metal compound particles and the particles other than the metal compound particles is as small as possible, and that polyester as a recycled product is blended and used from the viewpoint of cost reduction and environmental load reduction.

(Thickness)
The thickness of the polyester film is preferably 10 μm or more or 1000 μm or less, more preferably 20 μm or more or 500 μm or less, particularly preferably 30 μm or more or 400 μm or less, and more preferably 38 μm or more or 350 μm or less.
By using the film within the above range, the hardness (stiffness) and handleability of the film can be made sufficient, and the film clogging in the transport process in the copying machine can be reduced.

When the polyester film has a multi-layer structure of three or more layers as described above, the thickness of each layer is preferably 1 μm or more or 50 μm or less, particularly 2 μm or more or 40 μm or less, particularly 3 μm or more or 30 μm or less, among them. It is more preferably 4 μm or more or 25 μm or less. By using it in the above range, it is possible to fully exhibit the performance of the metal compound particles described later and particles other than the metal compound particles, and the manufacturing cost can be suppressed at a low cost.

(Apparent density)
The lower limit of the apparent density of the polyester film is 0.7 g / cm ³ or more, preferably 0.75 g / cm ³ or more, and more preferably 0.8 g / cm ³ or more. By setting the lower limit of the apparent density to the above range, the strength of the film can be maintained, and the film is jammed in the transport process in the copying machine when used as a recording material in place of the copy paper or printer paper which is an information printing medium. Can be reduced, and optimum printing can be performed.
On the other hand, the upper limit of the apparent density is 1.3 g / cm ³ or less, preferably 1.2 g / cm ³ or less, and more preferably 1.1 g / cm ³ or less. By setting the upper limit of the apparent density to the above range, the work load when carrying a large amount of printed matter is reduced, and further, the environmental load is reduced and the cost is reduced by reducing the CO ₂ generated in the film (sheet) transportation process. It will be possible.
The apparent density of the polyester film can be adjusted by blending an incompatible resin with a lighter specific gravity than polyester, which is the main component resin, and stretching it in at least one axial direction to adjust the formation of ultrafine independent cavities inside the film. can. However, the method is not limited to these methods.

<Physical characteristics of polyester film>
The arithmetic mean roughness (Ra) of the surface of the polyester film is based on JIS B0601 (2001). The arithmetic mean roughness (Ra) varies depending on the intended use, but the upper limit is usually 950 nm or less, preferably 850 nm or less, and more preferably 800 nm or less. By using a polyester film having an arithmetic average roughness (Ra) in the above range, characters and images of an image forming substance containing a thermoplastic resin formed on the film surface can be easily adhered and easily peeled off. It can be removed, and the film tends to be repeatedly used as a recording material for copying paper and printer paper.
On the other hand, the lower limit of the arithmetic mean roughness (Ra) is usually 100 nm or more, preferably 200 nm or more, more preferably 300 nm or more, still more preferably 350 nm or more. By setting the arithmetic average roughness (Ra) in the above range, it is possible to have sufficient concealment and transportability, and the film should be the most suitable film to be used as a recording material for copying paper and printer paper. Tends to be possible. Furthermore, it tends to have sufficient writeability.

The b value (reflection method), which is an index indicating the yellowness of the polyester film, is usually 0.00 or less, preferably -0.20 or less, more preferably -0.40 or less, still more preferably -0.50 or less. Particularly preferably, it is −0.60 or less, and the lower limit is not particularly limited, but −5.0 or more is preferable. By setting the b value in the above range, the yellowness can be suppressed and the whiteness can be improved. Further, when used as a recording material for color printing, the obtained image quality tends to be excellent.

The polyester film has an absolute value of heat shrinkage in the film longitudinal direction (MD) and film width direction (TD) at 150 ° C. for 30 minutes, which is usually 2.8% or less, preferably 2.3% or less, more preferably. It is 2.0% or less.
By setting the heat shrinkage rate of the polyester film within the above range, it is possible to prevent the dimensional stability of the film from being impaired by the influence of heat when printing on the material to be recorded by a method such as an electrophotographic method or a thermal transfer method. can. In particular, it is possible to suppress the occurrence of wrinkles in the polyester film even in the edge portion of the film (sheet), that is, the portion where wrinkles are likely to occur, and the characters and images are distorted or uneven, resulting in deterioration of image quality. It tends to be possible to suppress the phenomenon. Further, once wrinkles are generated, they cannot be erased and cannot be repeatedly used as a recording material for copying paper or printer paper. Therefore, it is preferable to prevent wrinkles from occurring as much as possible.

The hiding power (OD) of the polyester film is usually 0.30 or more, preferably 0.35 or more, more preferably 0.40 or more, still more preferably 0.45 or more when a single film is measured with a Macbeth densitometer. Is. When used in the above range, show-through when printed on both sides of the film is reduced, and high-quality characters and images tend to be obtained. On the other hand, the upper limit of the concealing property (OD) is not particularly limited, but in consideration of the balance of other physical properties, 1.0 or less is preferable, and 0.9 or less is more preferable.

The whiteness of the polyester film is measured by measuring the hunter whiteness (Wb) of a single film with a colorimeter, and the lower limit is usually 80.0% or more, preferably 81.0% or more, more preferably 82. It is 0% or more, more preferably 83.0% or more, and particularly preferably 83.5% or more. By setting the whiteness within the above range, characters and images are high-definition when used as a recording material for copy paper or printer paper, which is an information printing medium instead of paper, especially when color printing is performed. It tends to be preferable in terms of quality. Further, although it depends on the intended use, a higher value is preferable in order to give a high-class feeling, and the upper limit is not particularly limited. On the other hand, when used for applications where gloss is a concern, the upper limit of the preferable range is 95.0% or less.

<Functional layer>
The functional layer constituting the laminated white polyester film will be described.
The functional layer in the present laminated white polyester film is a cured product formed from a composition containing 1% by weight or more of a cross-linking agent, and further contains a mold release agent, an antistatic agent, a polymer as a base resin, and the like, if necessary. You may.
The functional layer can serve, for example, as a recorded layer to which the image-forming substance directly adheres to the layer surface. The recorded layer in the present invention is a layer that not only fixes the attached image-forming substance but also removes the image-forming substance together with the resin layer when the resin layer described later is provided.

[Crosslinking agent]
The functional layer in this laminated white polyester film is made strong by a cross-linking agent, and is used as a recording material for copying paper and printer paper to prevent scraping and scratching in the transport process in the copying machine, and to be made of an image forming substance. By reducing erosion, characters and images can be recorded accurately without bleeding. Further, the functional layer can retain various functions and can be reused as a recorded material after removing characters and images.

As the cross-linking agent, conventionally known materials can be used, and examples thereof include melamine compounds, oxazoline compounds, isocyanate compounds, epoxy compounds, carbodiimide compounds, silane coupling compounds, hydrazide compounds, and aziridine compounds. Among them, melamine compounds, oxazoline compounds, isocyanate compounds, epoxy compounds, carbodiimide compounds, and silane coupling compounds are preferable. In order to further enhance the strength of the functional layer, a melamine compound or an oxazoline compound is preferable, and a melamine compound is more preferable. In order to improve the adhesion of the base material to the film, oxazoline compounds, isocyanate compounds, epoxy compounds and carbodiimide compounds are preferable, and oxazoline compounds and isocyanate compounds are particularly preferable. In addition to the above-mentioned properties, it was also found that the isocyanate-based compound has a property of easily maintaining the performance of the functional layer while continuing the study.

One type of cross-linking agent may be used, or two or more types may be used in combination. In the study, in order to maintain various performances (peeling force, surface intrinsic resistance, etc.) of the functional layer (to reduce the amount of change due to repeated peeling operations), it is better to use two or more types together rather than using them alone. We have found that it may be preferable. In particular, it has been found that the combined use of the melamine compound and the oxazoline compound has a characteristic that the performance of the functional layer can be easily maintained in a range smaller than that when the cross-linking agent is used alone.

Furthermore, it has been found that among the cross-linking agents, the isocyanate-based compound has a characteristic, and it is easy to maintain various performances of the functional layer even when used alone as a cross-linking agent or when two or more kinds of cross-linking agents are used in combination. However, when an isocyanate compound is used, the peeling force tends to be higher and the surface intrinsic resistance tends to be higher than when it is not used. Therefore, it is necessary to consider the application in use. be. That is, in order to maintain the performance of the functional layer, it is effective to use a melamine compound and an oxazoline compound in combination, and it is also preferable to use an isocyanate compound. A film having a more optimum functional layer can be obtained.

Further, the functional layer tends to be able to impart the property of improving the wettability to the polyester film by the cross-linking agent.
According to the studies by the present inventors, when the polyester film as the base material contains a polymer incompatible with polyester, particularly polyolefin, the wettability is extremely poor when the functional layer is provided by coating. It turned out that it repels the coating liquid. However, surprisingly, it was found that the cross-linking agent greatly improves the wettability of the functional layer. Specifically, an oxazoline compound, an isocyanate-based compound, an epoxy compound, and a silane coupling compound are preferable for improving wettability, and an oxazoline compound and an isocyanate-based compound are more preferable.

That is, from a comprehensive point of view, the melamine compound is most preferable from the viewpoint of strengthening the functional layer, while the oxazoline compound or the isocyanate-based compound is preferable from the viewpoint of adhesion to the polyester film and wettability. .. Further, from the viewpoint of maintaining the performance of the functional layer, the combined use of the melamine compound and the oxazoline compound or the isocyanate-based compound is preferable, and the combined use of the melamine compound, the oxazoline compound and the isocyanate-based compound has more optimum functions. Can be layered.

The melamine compound used as the cross-linking agent is a compound having a melamine skeleton in the compound. For example, an alkyrylated melamine derivative or an alkyrylated melamine derivative is reacted with an alcohol to partially or completely etherify. Compounds and mixtures thereof can be used. As the alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like are preferably used. Further, the melamine compound may be either a monomer or a multimer of a dimer or more, or a mixture thereof may be used. Considering the reactivity with various compounds, it is preferable that the melamine compound contains a hydroxyl group. Further, a melamine cocondensed with urea or the like can be used, or a catalyst can be used to increase the reactivity of the melamine compound.

As the oxazoline compound used as the cross-linking agent, a polymer containing an oxazoline group is particularly preferable, and it can be prepared by polymerization of an addition-polymerizable oxazoline group-containing monomer alone or with another monomer. Additive polymerizable oxazoline group-containing monomers include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-Isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like can be mentioned, and one or a mixture of two or more thereof can be used.

Among these, 2-isopropenyl-2-oxazoline is suitable because it is easily available industrially. The other monomer is not limited as long as it is a monomer copolymerizable with the addition-polymerizable oxazoline group-containing monomer, and is not limited to (meth) acrylic acid esters such as alkyl (meth) acrylate; acrylic acid, methacrylic acid, itaconic acid, and maleine. Unsaturated carboxylic acids such as acids, fumaric acid, crotonic acid, styrene sulfonic acid and salts thereof (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); unsaturated nitriles such as acryliconitrile and methacrylonitrile; Unsaturated amides such as (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as methyl vinyl ether and ethyl vinyl ether Α-olefins such as ethylene and propylene; halogen-containing α and β-unsaturated monomers such as vinyl chloride, vinylidene chloride and vinyl fluoride; α, β-unsaturated aromatics such as styrene and α-methylstyrene. Monomers and the like can be mentioned, and one or more of these monomers can be used. Examples of the above-mentioned alkyl include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, a 2-ethylhexyl group, a cyclohexyl group and the like.

The amount of the oxazoline group of the oxazoline compound is preferably in the range of 0.5 to 10 mmol / g, more preferably 1 to 9 mmol / g, still more preferably 3 to 8 mmol / g, and particularly preferably 4 to 6 mmol / g. By using it in the above range, an optimum functional layer can be formed.

The isocyanate-based compound used as the cross-linking agent is an isocyanate or a compound having an isocyanate derivative structure typified by blocked isocyanate. Examples of the isocyanate include aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyldiisocyanate, phenylenedi isocyanate and naphthalenedi isocyanate; and aromatic rings such as α, α, α', α'-tetramethylxylylene diisocyanate. Aliphatic isocyanates; aliphatic isocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate; cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, methylenebis (4-cyclohexylisocyanate), isopropyridene dicyclohexyldiisocyanate and the like. The alicyclic isocyanate of the above is exemplified.

Further, polymers and derivatives such as burettes, isocyanurates, uretdiones, and carbodiimide-modified compounds of these isocyanates can also be mentioned. These may be used alone or in combination of two or more. Among the above isocyanates, aliphatic or alicyclic isocyanates are more preferable than aromatic isocyanates in order to avoid yellowing due to ultraviolet rays.

When used in the state of blocked isocyanate, the blocking agent includes, for example, phenolic compounds such as heavy sulfites, phenol, cresol and ethylphenol, and alcoholic compounds such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol and ethanol. Compounds, active methylene compounds such as dimethyl malonate, diethyl malonate, methyl isobutanoyl acetate, methyl acetoacetate, ethyl acetoacetate, acetylacetone, mercaptan compounds such as butyl mercaptan and dodecyl mercaptan, ε-caprolactam, δ-valerolactam, etc. Examples thereof include lactam compounds, amine compounds such as diphenylaniline, aniline, and ethyleneimine, acetanilide, acid amide compounds of acetate amide, formaldehyde, acetoaldoxime, acetone oxime, methyl ethyl ketone oxime, and oxime compounds such as cyclohexanone oxime. These may be used alone or in combination of two or more. Among the above, an isocyanate compound blocked by an active methylene compound is particularly preferable from the viewpoint of adhesion to the polyester film, wettability to the polyester film, and maintenance of the performance of the functional layer.

Further, the isocyanate-based compound may be used alone, or may be used as a mixture or a bond with various polymers. It is also preferable to use a mixture or a bond with a polyester resin or a urethane resin in the sense of improving the dispersibility and crosslinkability of the isocyanate compound.

Examples of the epoxy compound used as the cross-linking agent include a condensate of epichlorohydrin with a hydroxyl group such as ethylene glycol, polyethylene glycol, glycerin, polyglycerin, and bisphenol A, and an amino group, and examples thereof include polyepoxy compounds and diepoxy compounds. , Monoepoxy compounds, glycidylamine compounds and the like. Examples of the polyepoxy compound include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyltris (2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, and trimethylolpropane. Polyglycidyl ether; examples of the diepoxy compound include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and propylene glycol diglycidyl ether. , Polypropylene glycol diglycidyl ether, Polytetramethylene glycol diglycidyl ether; Examples of monoepoxy compounds include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and glycidyl amine compounds N, N, N', N. ′ -Tetraglycidyl-m-xylylene diamine, 1,3-bis (N, N-diglycidylamino) cyclohexane and the like can be mentioned.

The carbodiimide-based compound used as the cross-linking agent is a compound having one or more carbodiimide or a carbodiimide derivative structure in the molecule. Polycarbodiimide-based compounds having two or more carbodiimide structures in the molecule are preferable for better functional layer strength and the like.

The carbodiimide-based compound used as the cross-linking agent can be synthesized by a conventionally known technique, and a condensation reaction of a diisocyanate compound is generally used. The diisocyanate compound is not particularly limited, and any aromatic or aliphatic type can be used. Specifically, tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, phenylenedi isocyanate, naphthalenedi isocyanate, hexa. Examples thereof include methylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexanediisocyanate, methylcyclohexanediisocyanate, isophorone diisocyanate, dicyclohexyldiisocyanate, and dicyclohexylmethane diisocyanate.

Furthermore, in order to improve the water solubility and water dispersibility of the polycarbodiimide compound, a surfactant may be added, and a quaternary ammonium salt of a polyalkylene oxide or a dialkylaminoalcohol may be added to the extent that the effect of the present invention is not lost. , Hydrophilic monomers such as hydroxyalkyl sulfonates may be added and used.

The silane coupling compound used as the cross-linking agent is an organic silicon compound having an organic functional group and a hydrolyzing group such as an alkoxy group in one molecule. For example, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-) Propylcyclohexyl) Epyl group-containing compounds such as ethyltrimethoxysilane; vinyl group-containing compounds such as vinyltrimethoxysilane and vinyltriethoxysilane; styryl group-containing compounds such as p-styryltrimethoxysilane and p-styryltriethoxysilane; 3- (Meta) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxylpropylmethyldiethoxysilane, etc. (Meta) Acrylic group-containing compound; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl)- 3-Aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldiethoxysilane, 3-triethoxysilyl-N -Amino group-containing compounds such as (1,3-dimethylbutylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane; tris (trimethoxysilylpropyl) Isocyanurate group-containing compounds such as isocyanurate, tris (triethoxysilylpropyl) isocyanurate; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldi Examples thereof include mercapto group-containing compounds such as ethoxysilane.

Among the above compounds, from the viewpoint of the strength of the functional layer and the adhesion to the polyester film, an epoxy group-containing silane coupling compound, a double bond-containing silane coupling compound such as a vinyl group or a (meth) acrylic group, and an amino group-containing silane. Coupling compounds are more preferred.

The cross-linking agent usually exists in a state of reacting with the polymer or the cross-linking agent itself in the drying process or the film forming process. Therefore, in the functional layer of the present laminated white polyester film, it exists as an unreacted product of these cross-linking agents, a compound after the reaction, or a mixture thereof (a compound derived from the cross-linking agent).

It is essential that the lower limit of the content of the cross-linking agent in the functional layer is 1% by weight or more, preferably 3% by weight or more, more preferably 5% by weight or more, still more preferably 8% by weight or more, and particularly preferably. It is 10% by weight or more. The upper limit is usually 80% by weight or less, preferably 70% by weight or less, more preferably 65% by weight or less, still more preferably 60% by weight or less, and particularly preferably 55% by weight or less. By using the cross-linking agent in the above range, the strength of the functional layer can be improved, the adhesion to the polyester film is improved, and the wettability to the polyester film when the functional layer is provided by coating is improved. It tends to be easy to achieve excellent appearance and maintenance of various performances of the functional layer, and it can be reused as a material to be recorded after removing characters and images.
Here, the content of the cross-linking agent means the content ratio in the non-volatile component in the composition (coating liquid) before the cross-linking reaction, and also means the same meaning in the functional layer after the cross-linking reaction.

When the melamine compound alone is used as the cross-linking agent, the content of the melamine compound in the functional layer is usually 1% by weight or more, preferably 8% by weight or more, more preferably 20% by weight or more, still more preferably 35% by weight or more. The upper limit is usually 80% by weight or less, preferably 70% by weight or less, more preferably 60% by weight or less, still more preferably 55% by weight or less. By using the melamine compound in the above range, the functional layer can be strengthened and various performances of the functional layer can be maintained, so that it can be reused as a recording material after removing characters and images. Is.

In the case of the oxazoline compound alone as the cross-linking agent, the content of the oxazoline compound in the functional layer is usually 1% by weight or more, preferably 3% by weight or more, more preferably 5% by weight or more, still more preferably 10% by weight or more. Further, the upper limit is usually in the range of 80% by weight or less, preferably 70% by weight or less, more preferably 60% by weight or less, still more preferably 50% by weight or less. By using the oxazoline compound in the above range, the functional layer can be strengthened, the adhesion to the polyester film can be improved, the wettability to the polyester film can be improved, and various performances of the functional layer can be maintained. Therefore, it can be reused as a recorded material after removing characters and images.

When a melamine compound and an oxazoline compound are used in combination as a cross-linking agent, the content of the melamine compound in the functional layer is usually 1% by weight or more, preferably 3% by weight or more, more preferably 8% by weight or more, and usually. It is in the range of 75% by weight or less, preferably 60% by weight or less, and more preferably 50% by weight or less. The content of the oxazoline compound in the functional layer is usually 1% by weight or more, preferably 5% by weight or more, more preferably 8% by weight or more, and usually 50% by weight or less, preferably 40% by weight or less. More preferably, it is in the range of 30% by weight or less. By using the cross-linking agent in the above range, various performances of the functional layer can be maintained well, so that it can be reused as a material to be recorded after removing characters and images.

When an isocyanate-based compound is used as the cross-linking agent (either alone or in combination with another cross-linking agent), the content of the isocyanate-based compound in the functional layer is usually 1% by weight or more, preferably 3% by weight. As described above, it is more preferably 5% by weight or more, and usually 50% by weight or less, preferably 40% by weight or less, and more preferably 30% by weight or less. By using the isocyanate compound in the above range, the adhesion to the polyester film is improved, the wettability to the polyester film is improved, and the various performances of the functional layer are well maintained. After removing the image, it can be reused as a recorded material.

[Antistatic agent]
When this laminated white polyester film is used as a recording material for copiers and printer paper, it is used to prevent double feeding in paper transport of copiers and multifunction devices, and to prevent paper from sticking to each other when handling paper. It is preferable to have a functional layer containing the agent on at least one side. Further, by containing an antistatic agent in the functional layer, the film is not clogged in the compound machine, the printed film is not double-fed, and the printed film can be independently conveyed one by one, and dust adheres to the film. It has been found that it is possible to obtain a high-quality film or a film-printed matter with good image quality because it is possible to prevent the above.

The antistatic agent contained in the functional layer is not particularly limited, and a conventionally known antistatic agent can be used. For example, a polymer-type antistatic agent is preferable because it has good heat resistance and moisture resistance.
Examples of the polymer type antistatic agent include a compound having an ammonium group, a polyether compound, a compound having a sulfonic acid group, a betaine compound, a conductive polymer and the like.
Considering the antistatic performance, a compound having an ammonium group or a compound having a sulfonic acid group is preferable, and considering compatibility with other materials forming a functional layer such as a mold release agent, a compound having an ammonium group is more preferable. preferable. Further, the conductive polymer is most preferable because it has the best antistatic property. However, the cost of the material and its use may be restricted in applications where coloring is extremely disliked.

Examples of the above-mentioned compound having an ammonium group include an aliphatic amine, an alicyclic amine, an ammonium compound of an aromatic amine, and the like. The compound having an ammonium group is preferably a compound having a polymer type ammonium group, and the ammonium group has a structure incorporated in the main chain or side chain of the polymer, not as a counter ion. Is preferable. For example, a polymer obtained by polymerizing a monomer containing an addition-polymerizable ammonium group or a precursor of an ammonium group such as an amine can be mentioned and is preferably used. As the polymer, a monomer containing an addition-polymerizable ammonium group or a precursor of an ammonium group such as an amine may be polymerized alone, or it may be a copolymer of a monomer containing these and another monomer. You may.

Among the compounds having an ammonium group, a compound having a pyrrolidinium ring is also preferable in that it is excellent in antistatic property and heat stability.

The two substituents bonded to the nitrogen atom of the compound having a pyrrolidinium ring are independently an alkyl group, a phenyl group, etc., and even if these alkyl groups and phenyl groups are substituted with the groups shown below. good. Substitutable groups are, for example, hydroxyl groups, amide groups, ester groups, alkoxy groups, phenoxy groups, naphthoxy groups, thioalkoxy, thiophenoxy groups, cycloalkyl groups, trialkylammonium alkyl groups, cyano groups and halogens. Further, the two substituents bonded to the nitrogen atom may be chemically bonded, for example,-(CH ₂ ) m- (m = an integer of 2 to 5), -CH (CH ₃ ) CH. (CH ₃ )-, -CH = CH-CH = CH-, -CH = CH-CH = N-, -CH = CH-N = CH-, -CH ₂ OCH ₂ -,-(CH ₂ ) ₂ O (CH ₂ ) ₂ -and the like.

The polymer having a pyrrolidinium ring is obtained by cyclizing and polymerizing a diallylamine derivative using a radical polymerization catalyst. Polymerization is known as a polymerization initiator such as hydrogen peroxide, benzoyl peroxide, and tertiary butyl peroxide in water or a polar solvent such as methanol, ethanol, isopropanol, formamide, dimethylformamide, dioxane, and acetonitrile as a solvent. It can be carried out by a method, but is not limited to these. In the present invention, a compound having a carbon-carbon unsaturated bond polymerizable with the diallylamine derivative may be used as the copolymerization component.

Further, it is also preferable that the antistatic agent is a polymer having the structure of the following formula (Chemical formula 1) in that it is excellent in antistatic property and moisture resistance heat stability. A single polymer or copolymer having the structure of the following formula (Chemical formula 1), or a plurality of other components may be copolymerized.

For example, in the above formula, the substituent R ¹ is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, a hydrocarbon group such as a phenyl group, R ² is -O-, -NH- or -S-, and R ³ is. An alkylene group having 1 to 20 carbon atoms or another structure capable of forming the structure of formula 1, R ⁴ , R ⁵ and R ⁶ are independently hydrogen atoms, an alkyl group having 1 to 20 carbon atoms, and a phenyl group. A hydrocarbon group such as, or a hydrocarbon group to which a functional group such as a hydroxyalkyl group is added, X ^- is various counter ions.

Among the above, the substituent R ¹ is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms in the formula (formulation 1), particularly from the viewpoint of excellent antistatic property and moisture resistance and heat stability. R ³ is preferably an alkyl group having 1 to 6 carbon atoms, and R ⁴ , R ⁵ and R ⁶ are preferably independent hydrogen atoms or alkyl groups having 1 to 6 carbon atoms, respectively, more preferably. In, any one of R ⁴ , R ⁵ , and R ⁶ is a hydrogen atom, and the other substituent is an alkyl group having 1 to 4 carbon atoms.

Examples of the anion that becomes a counter ion (counter ion) of the ammonium group of the above-mentioned compound having an ammonium group include ions such as halogen ion, sulfonate, sulfate, phosphate, nitrate, and carboxylate.

The number average molecular weight of the compound having an ammonium group is usually 1000 to 500,000, preferably 2000 to 350,000, and more preferably 5000 to 200,000. If the molecular weight is less than 1000, the strength of the functional layer may be weakened or the heat resistance may be inferior. On the other hand, when the molecular weight exceeds 500,000, the viscosity of the coating liquid becomes high, and the handleability and the coatability may deteriorate.

Examples of the polyether compound include polyethylene oxide, a polyether ester amide, and an acrylic resin having polyethylene glycol in the side chain.

The compound having a sulfonic acid group is a compound containing a sulfonic acid or a sulfonate in the molecule, and a compound having a large amount of the sulfonic acid or the sulfonate such as polystyrene sulfonic acid is preferably used. ..

Examples of the conductive polymer include polythiophene-based, polyaniline-based, polypyrrole-based, polyacetylene-based, and among them, for example, polythiophene-based polymer in which poly (3,4-ethylenedioxythiophene) is used in combination with polystyrene sulfonic acid. It is preferably used. Conductive polymers are more suitable than the other antistatic agents described above in that they have a lower resistance value. However, on the other hand, in applications where coloring and cost are a concern, it is necessary to take measures such as reducing the amount used.

The lower limit of the content of the antistatic agent in the functional layer is usually 0% by weight or more, preferably 3% by weight or more, more preferably 5% by weight or more, still more preferably 10% by weight or more, and particularly preferably 20% by weight or more. be. The upper limit is usually 80% by weight or less, preferably 70% by weight or less, more preferably 60% by weight or less, still more preferably 55% by weight or less, and particularly preferably 50% by weight or less. By using the antistatic agent in the above range, sufficient antistatic properties can be obtained, which is effective in preventing the films from sticking to each other and the adhesion of dust, which improves print transportability and image quality. It tends to be excellent.

[Release agent]
It is preferable that the functional layer is provided with a mold release performance so that the image-forming substance containing the thermoplastic resin formed on the film surface can be suitably peeled off and removed after printing.
The functional layer having the mold release performance may be the same as or different from the functional layer containing the antistatic agent. In particular, for the reason described later, it is preferable that the functional layer containing the antistatic agent has a mold release performance. When the functional layer having the mold release performance and the functional layer containing the antistatic agent are different layers, it is preferable to use the functional layer having the mold release performance as the outer layer.
It has been found that by providing an appropriate mold release performance to the functional layer, the function of adhering the image-forming substance to the film surface and the function of peeling and removing the image-forming substance can be more appropriately performed. That is, we have succeeded in finding a method to realize the contradictory properties of adhesion and peeling with one functional layer at a higher level. This technique can be said to be a very effective technique considering that the peeling performance cannot be realized in the functional layer having general peeling performance, while the adhesive performance cannot be realized in the functional layer having general peeling performance. .. It is also added that even if a functional layer having adhesive performance and a functional layer having peeling performance are laminated, it is difficult to exhibit either performance, and only the characteristics of the layer provided on the top are alive. Keep it.
In order to impart mold release performance to the image forming substance, the functional layer preferably contains a mold release agent. By containing a mold release agent in the functional layer, it is possible to further enhance the function of the polyester film obtained by containing a polymer incompatible with polyester to easily peel off and remove characters and images due to an image forming substance. It can be done, and it becomes possible to make the repeated removal more reliable. Further, for example, when the peeling performance of the polyester film deteriorates due to repeated removal, the peeling performance is supplemented by the functional layer, and conversely, when the peeling performance of the functional layer deteriorates due to repeated removal, the polyester film side. It is also possible to supplement. That is, it has been found that an effect that cannot be achieved only by the polyester film and that cannot be achieved only by containing a release agent in the functional layer can be exhibited.

The release agent is not particularly limited, and conventionally known release agents can be used, and examples thereof include long-chain alkyl group-containing compounds, fluorine compounds, silicone compounds, and waxes. Among these, long-chain alkyl compounds and fluorine compounds are preferable, and long-chain alkyl compounds are more preferable, from the viewpoints of being less contaminated and excellent in peeling and removing image-forming substances. Further, when it is particularly important to remove the peeling of the image forming substance, a silicone compound is preferable. In addition, wax is effective when it is desired to emphasize the printability of the image-forming substance on the surface. These release agents may be used alone or in a plurality of types.

Further, when the functional layer is provided by coating, a long-chain alkyl group-containing compound is preferable among the above-mentioned mold release agents from the viewpoint of wettability to the polyester film of the base material.

The long-chain alkyl group-containing compound is a compound having a linear or branched alkyl group having usually 6 or more carbon atoms, preferably 8 or more carbon atoms, and more preferably 12 or more carbon atoms.
Examples of the alkyl group include a hexyl group, an octyl group, a decyl group, a lauryl group, an octadecyl group, a behenyl group and the like.
Examples of the compound having an alkyl group include various long-chain alkyl group-containing polymer compounds, long-chain alkyl group-containing amine compounds, long-chain alkyl group-containing ether compounds, and long-chain alkyl group-containing quaternary ammonium salts. .. Considering heat resistance and stain resistance, a polymer compound is preferable. Further, from the viewpoint of effectively obtaining releasability, a polymer compound having a long-chain alkyl group in the side chain is more preferable.

The polymer compound having a long-chain alkyl group in the side chain can be obtained by reacting a polymer having a reactive group with a compound having an alkyl group capable of reacting with the reactive group. Examples of the reactive group include a hydroxyl group, an amino group, a carboxyl group, an acid anhydride and the like. Examples of the compound having these reactive groups include polyvinyl alcohol, polyethyleneimine, polyethyleneamine, a reactive group-containing polyester resin, and a reactive group-containing poly (meth) acrylic resin. Among these, polyvinyl alcohol is preferable in consideration of releasability and ease of handling.

Examples of the compound having an alkyl group capable of reacting with the above reactive group include long-chain alkyl group-containing isocyanates such as hexyl isocyanate, octyl isocyanate, decyl isocyanate, lauryl isocyanate, octadecyl isocyanate and behenyl isocyanate; hexyl chloride and octyl chloride. , Long-chain alkyl group-containing acid chlorides such as desocyanate, lauryl chloride, octadecyl chloride, behenyl chloride; long-chain alkyl group-containing amines; long-chain alkyl group-containing alcohols and the like. Among these, long-chain alkyl group-containing isocyanates are preferable, and octadecyl isocyanates are particularly preferable, in consideration of releasability and ease of handling.

Further, the polymer compound having a long-chain alkyl group in the side chain can also be obtained by a polymer of a long-chain alkyl (meth) acrylate or a copolymerization of the long-chain alkyl (meth) acrylate with another vinyl group-containing monomer. .. Examples of the long-chain alkyl (meth) acrylate include hexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, octadecyl (meth) acrylate, and behenyl (meth) acrylate. Be done.

The fluorine compound is a compound containing a fluorine atom in the compound. In order to reduce the contamination, a polymer containing a fluorine atom is preferable. Organic fluorine compounds are preferably used in terms of the appearance of coating by in-line coating. For example, fluoroalkyl group-containing compounds such as perfluoroalkyl group-containing compounds, polymers of olefin compounds containing fluorine atoms, and aromatics such as fluorobenzene are used. Examples include group fluorine compounds. From the viewpoint of releasability, a fluoroalkyl group-containing compound is preferable, and a perfluoroalkyl group-containing compound is particularly preferable. Further, as the fluorine compound, a compound containing a long-chain alkyl compound as described later can also be used.

Examples of the perfluoroalkyl group-containing compound include perfluoroalkyl (meth) acrylate, perfluoroalkylmethyl (meth) acrylate, 2-perfluoroalkylethyl (meth) acrylate, and 3-perfluoroalkylpropyl (meth) acrylate. Perfluoroalkyl group-containing (meth) acrylates such as 3-perfluoroalkyl-1-methylpropyl (meth) acrylate, 3-perfluoroalkyl-2-propenyl (meth) acrylate and their polymers; perfluoroalkyl methyl vinyl ether, Perfluoroalkyl group-containing vinyl ethers such as 2-perfluoroalkyl ethyl vinyl ether, 3-perfluoropropyl vinyl ether, 3-perfluoroalkyl-1-methylpropyl vinyl ether, 3-perfluoroalkyl-2-propenyl vinyl ether and their polymers. Can be mentioned. Considering heat resistance and stain resistance, it is preferably a polymer. The polymer may be a single compound alone or a polymer of a plurality of compounds.

Further, from the viewpoint of releasability, the perfluoroalkyl group preferably has 3 to 11 carbon atoms. Further, it may be a polymer with a compound containing a long-chain alkyl compound as described later. Further, from the viewpoint of adhesion to the substrate, it is also preferable that the polymer is a polymer with vinyl chloride.

Examples of the silicone compound include alkyl silicones such as dimethyl silicone and diethyl silicone, and phenyl silicone having a phenyl group, methyl phenyl silicone and the like. As the silicone, those having various functional groups can also be used, and examples thereof include an ether group, a hydroxyl group, an amino group, an epoxy group, a carboxylic acid group, a halogen group such as fluorine, and a perfluoroalkyl group. As other functional groups, silicones having a vinyl group and hydrogen silicones in which a hydrogen atom is directly bonded to a silicon atom are also common, and both are used in combination to form an addition type (type by an addition reaction between a vinyl group and a hydrogensilane). It can also be used as.

Further, as the silicone compound, modified silicone such as acrylic graft silicone, silicone graft acrylic, amino-modified silicone, and perfluoroalkyl-modified silicone can also be used. Considering heat resistance and stain resistance, it is preferable to use a curable silicone resin, and any of the curable reaction types such as condensation type, addition type, and active energy ray curable type can be used as the curable type.

The wax is a wax selected from natural waxes, synthetic waxes, and waxes containing them.

Natural waxes are plant-based waxes, animal-based waxes, mineral-based waxes, and petroleum-based waxes. Examples of the plant wax include candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil and the like. Examples of animal waxes include beeswax, lanolin, and whale wax. Examples of the mineral wax include montan wax, ozokerite, and selecin. Examples of petroleum wax include paraffin wax, microcrystalline wax, petrolatum and the like. Examples of the synthetic wax include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, acid amides, amines, imides, esters, ketones and the like.

Examples of the synthetic wax include synthetic hydrocarbons, modified waxes, hydrogenated waxes, higher fatty acid esters, fatty acid amides, amines, imides, ester waxes, ketones and the like.
Specific examples of synthetic hydrocarbons include Fisher Tropsch wax (also known as sazole wax) and polyethylene wax, as well as low molecular weight polymers (specifically, polymers having a number average molecular weight of 500 to 20000). The following polymers, that is, polypropylene, ethylene / acrylic acid copolymer, polyethylene glycol, polypropylene glycol, polyethylene glycol and polypropylene glycol block or graft conjugate, and the like can be mentioned.

Specific examples of the modified wax include a montan wax derivative, a paraffin wax derivative, and a microcrystalline wax derivative. The derivative here is a compound obtained by any treatment of purification, oxidation, esterification, saponification, or a combination thereof. Specific examples of the hydrogenated wax include hardened castor oil and hardened castor oil derivatives.

Among them, synthetic wax is preferable, and polyethylene wax is more preferable, and polyethylene oxide wax is further preferable, from the viewpoint of stabilizing properties such as blocking. The number average molecular weight of the synthetic wax is usually 500 to 30,000, preferably 1000 to 15,000, and more preferably 2000 to 8000 from the viewpoint of stability of properties such as blocking and handleability.

The lower limit of the content of the release agent in the functional layer is usually 0% by weight or more, preferably 3% by weight or more, more preferably 5% by weight or more, still more preferably 8% by weight or more, and particularly preferably 10% by weight or more. Most preferably, it is 12% by weight or more. The upper limit is usually 80% by weight or less, preferably 70% by weight or less, more preferably 60% by weight or less, still more preferably 50% by weight or less, and particularly preferably 40% by weight or less. By using the release agent in the above range, it tends to be possible to improve the peelability while ensuring the adhesiveness with the image-forming substance, and to easily peel off and remove the image-forming substance.

[polymer]
In order to improve the ease of formation and adhesiveness of the image-forming substance of the functional layer and to improve the wettability to the polyester film when the functional layer is provided by coating, the functional layer has a polymer (antistatic agent described above). , Polymers other than mold release agents and cross-linking agents described below) are preferably further contained.

As the polymer used for the functional layer, a conventionally known polymer can be used. Specific examples of the polymer include acrylic resin, urethane resin, polyester resin, polyvinyl (polyvinyl alcohol, vinyl chloride vinyl acetate copolymer, etc.), polyalkylene glycol, polyalkyleneimine, methyl cellulose, hydroxycellulose, starches and the like. .. Among these, acrylic resin, urethane resin, polyester resin, and polyvinyl alcohol are preferable, and acrylic resin, urethane resin, etc. Polyester resin is more preferable, and acrylic resin and urethane resin are further preferable. Further, acrylic resin and polyvinyl alcohol are preferable from the viewpoint of stabilizing the antistatic performance and the mold release performance, or the stability in the state of the coating liquid when the functional layer is formed by coating. Considering the overall performance, acrylic resin or urethane resin is preferable, and acrylic resin is particularly preferable.

The acrylic resin as the polymer contained in the functional layer is a polymer composed of a polymerizable monomer containing an acrylic-based or methacrylic-based monomer. These may be homopolymers or copolymers, and may be copolymers with polymerizable monomers other than acrylic and methacrylic monomers. Further, a copolymer of these polymers and other polymers (for example, polyester, polyurethane, etc.) is also included. For example, block copolymers and graft copolymers. Alternatively, a polymer (in some cases, a mixture of polymers) obtained by polymerizing a polymerizable monomer in a polyester solution or a polyester dispersion is also included. Similarly, a polymer (in some cases, a mixture of polymers) obtained by polymerizing a polymerizable monomer in a polyurethane solution or a polyurethane dispersion is also included. Similarly, a polymer (in some cases, a polymer mixture) obtained by polymerizing a polymerizable monomer in another polymer solution or dispersion is also included. It is also possible to contain a hydroxyl group and an amino group in order to further improve the adhesion.

The polymerizable monomer is not particularly limited, and is, for example, various carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, and citraconic acid, and salts thereof; Various hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monobutylhydroquilfumarate, monobutylhydroxyitaconate; methyl Various (meth) acrylic acid esters such as (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate; (meth) acrylamide, diacetone acrylamide, Various nitrogen-containing compounds such as N-methylolacrylamide or (meth) acrylonitrile; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, vinyltoluene; various vinyl esters such as vinyl propionate; Various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane; phosphorus-containing vinyl-based monomers; various vinyl halides such as vinyl chloride and billidene chloride; Examples thereof include various conjugated dienes such as.

The urethane resin as the polymer contained in the functional layer is a polymer compound having a urethane bond in the molecule, and is usually produced by a reaction between a polyol and an isocyanate. Examples of the polyol include polyester polyols, polycarbonate polyols, polyether polyols, polyolefin polyols, and acrylic polyols, and these compounds may be used alone or in a plurality of types.

Examples of the polyester polyols include polyvalent carboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelli acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or theirs. Acid anhydrides and polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butane Diol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4- Pentandiol, 2-methyl-2-propyl-1,3-propanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol , 2,5-dimethyl-2,5-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl -2-Hexyl-1,3-propanediol, cyclohexanediol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyldialkanolamine, lactonediol, etc.), lactones such as polycaprolactone Examples thereof include those having a derivative unit of the compound.

The above polycarbonate polyols are obtained from polyhydric alcohols and carbonate compounds by a dealcohol reaction. Examples of polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentane. Glycol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decane Examples thereof include diol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 3,3-dimethylol heptane. Examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate and the like, and examples of the polycarbonate-based polyols obtained from these reactions include poly (1,6-hexylene) carbonate and poly (3-). Methyl-1,5-pentylene) carbonate and the like can be mentioned.

Examples of the above-mentioned polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol and the like.

Among the above-mentioned polyols, polyester polyols and polycarbonate polyols are more preferable in consideration of compatibility with other components of the functional layer, stabilization of antistatic performance and mold release performance.

Examples of the polyisocyanate compound used for obtaining a urethane resin include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyldiisocyanate, phenylenedi isocyanate, naphthalenediocyanate, and trizine diisocyanate, α, α, α', An aliphatic diisocyanate having an aromatic ring such as α'-tetramethylxylylene diisocyanate, methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, aliphatic diisocyanate such as hexamethylene diisocyanate, cyclohexanediisocyanate, methylcyclohexanediisocyanate, isophorone diisocyanate. , Dicyclohexylmethane diisocyanate, alicyclic diisocyanate such as isopropyridene dicyclohexyldiisocyanate and the like are exemplified. These may be used alone or in combination of two or more.

A chain extender may be used when synthesizing the urethane resin, and the chain extender is not particularly limited as long as it has two or more active groups that react with isocyanate groups, and is generally a hydroxyl group. Alternatively, a chain extender having two amino groups can be mainly used.

Examples of the chain extender having two hydroxyl groups include aliphatic glycols such as ethylene glycol, propylene glycol and butanediol, aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene, neopentyl glycol hydroxypivalate and the like. Glycols such as ester glycols can be mentioned. Examples of the chain extender having two amino groups include aromatic diamines such as tolylene diamine, xylylene diamine, and diphenylmethanediamine, ethylenediamine, propylenediamine, hexanediamine, 2,2-dimethyl-1,3-. Propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10- Aliper diamines such as decanediamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, isoprovilitincyclohexyl-4,4'-diamine, 1,4-diaminocyclohexane, 1, , 3-Bisaminomethylcyclohexane and other alicyclic diamines and the like.

The above urethane resin may use a solvent as a medium. Water is preferably used as a medium.
For dispersing or dissolving the urethane resin in water, there are a forced emulsification type using an emulsifier, a self-emulsifying type in which a hydrophilic group is introduced into the urethane resin, a water-soluble type, and the like. In particular, the self-emulsifying type in which an ionic group is introduced into the structure of the urethane resin to form an ionomer is preferable because it is excellent in storage stability of the liquid and the water resistance and transparency of the obtained functional layer.

At this time, examples of the ionic group to be introduced include various substances such as a carboxyl group, a sulfonic acid, a phosphoric acid, a phosphonic acid, and a quaternary ammonium salt. As a method for introducing a carboxyl group into the urethane resin, various methods can be taken in each stage of the polymerization reaction. For example, there are a method of using a resin having a carboxyl group as a copolymerization component at the time of prepolymer synthesis, and a method of using a component having a carboxyl group as one component of a polyol, a polyisocyanate, a chain extender and the like. In particular, a method of introducing a desired amount of carboxyl group according to the amount of this component charged by using a carboxyl group-containing diol is preferable.

For example, copolymerizing dimethylol propionic acid, dimethylol butanoic acid, bis- (2-hydroxyethyl) propionic acid, bis- (2-hydroxyethyl) butanoic acid, etc. with the diol used for polymerizing urethane resin. Can be done. Further, this carboxyl group is preferably in the form of a salt neutralized with ammonia, amines, alkali metals, inorganic alkalis and the like. Particularly preferred are ammonia, trimethylamine and triethylamine. In such a urethane resin, the carboxyl group from which the neutralizing agent has been removed in the drying step after coating can be used as a cross-linking reaction point by another cross-linking agent. This makes it possible to further improve the durability, solvent resistance, water resistance, blocking resistance, etc. of the obtained functional layer, in addition to being excellent in stability in the state of the liquid before coating.

Examples of the polyester resin as the polymer contained in the functional layer include those composed of the following polyvalent carboxylic acids and polyvalent hydroxy compounds as main constituents. That is, as the polyvalent carboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid and 2,6 -Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodiumsulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutal Acids, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, trimellitic acid monopotassium salt and ester-forming derivatives thereof can be used. As the polyvalent hydroxy compound, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2 -Methyl-1,5-pentandiol, neopentylglycol, 1,4-cyclohexanedimethanol, p-xylyleneglycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene Glycol, Polypropylene Glycol, Polytetramethylene Glycol, Polytetramethylene Oxidol Glycol, Dimethylolpropionic Acid, Glycerin, Trimethylol Propane, Sodium Dimethylolethylsulfonate, Potassium Dimethylolpropionate Etc. can be used. One or more of each of these compounds may be appropriately selected, and the polyester resin may be synthesized by a conventional polycondensation reaction.

The polyvinyl alcohol as the polymer contained in the functional layer has a polyvinyl alcohol moiety, and is, for example, conventionally known polyvinyl including a modified compound partially acetalized or butyralized with respect to polyvinyl alcohol. Alcohol can be used. The degree of polymerization of polyvinyl alcohol is not particularly limited, but usually 100 or more, preferably in the range of 300 to 40,000 is used. If the degree of polymerization is less than 100, the water resistance of the functional layer may decrease. The degree of saponification of polyvinyl alcohol is not particularly limited, but is preferably in the range of 50 mol% or more, more preferably 70 to 99 mol%, still more preferably 80 to 98 mol%, and particularly preferably 86 to 97 mol%. It is a polyvinyl acetate saponification.

The lower limit of the polymer content in the functional layer is usually 0% by weight or more, preferably 3% by weight or more, and more preferably 5% by weight or more. The upper limit is usually 80% by weight or less, preferably 70% by weight or less, more preferably 60% by weight or less, still more preferably 55% by weight or less, and particularly preferably 50% by weight or less. By using the polymer in the above range, it is easy to form an image-forming substance, the adhesion to the polyester film is improved, and the excellent appearance due to the improvement of the wettability to the polyester film when the functional layer is provided by coating. It tends to be easier to achieve the manifestation of various performances of the functional layer.

(Other ingredients)
It is also possible to use particles in combination with the functional layer for blocking and improving slipperiness as long as the gist of the present invention is not impaired. Further, it is also possible to use a defoaming agent, a coatability improving agent, a thickener, an organic lubricant, an ultraviolet absorber, an antioxidant, a foaming agent and the like in combination with the functional layer.

(Film thickness of functional layer)
The film thickness of the functional layer is usually 0.001 to 3 μm, preferably 0.005 to 1 μm, more preferably 0.01 to 0.5 μm, still more preferably 0.02 to 0.3 μm, and most preferably 0.03. It is ~ 0.2 μm. By setting the film thickness of the functional layer within the above range, it can be transported in a copying machine as a recording material for copying paper or printer paper, prevented from being scraped or scratched in the printing process, and suitable for printing characters and images by an image forming substance. It can be improved and various functions of the functional layer can be imparted.

(Arrangement of functional layers)
The functional layer can be provided on one side of the polyester film or on both sides of the polyester film.
When provided on both sides, a film that can be used as a recording material can be used on both sides, and there are advantages such as improved handleability of the film, which is preferable in terms of performance as on one side. Further, by providing the functional layers on both sides, it tends to be possible to improve the curl property due to environmental changes such as temperature and humidity.

(Antistatic performance of functional layer)
As the antistatic performance of the functional layer, the surface intrinsic resistance value (initial surface intrinsic resistance value) is usually 1 × 10 ¹³ Ω or less, preferably 1 × 10 ¹² Ω or less, more preferably 1 × 10 ¹¹ Ω or less, still more preferable. Is 1 × 10 ¹⁰ Ω or less, particularly preferably 5 × 10 ⁹ Ω or less. When the initial surface specific resistance value is within the above range, the film tends to be effective in preventing the films from sticking to each other and preventing dust and the like from adhering to each other. For this reason, when used as a recording material for copying paper or printer paper that can suitably transfer a toner image by a method such as an electrophotographic method or a thermal transfer method, double feeding is prevented in paper transport of copiers / multifunction machines, and paper is handled. It becomes possible to prevent the paper from sticking to each other.

Further, according to the measurement method described in the examples described later, the initial surface intrinsic resistance value and the surface intrinsic resistance value after the functional layer surface is repeatedly peeled three times (the surface intrinsic resistance value after the three peeling operations). The amount of change in surface intrinsic resistance calculated by dividing) is preferably small. The upper limit of the change in surface intrinsic resistance is usually 2000 or less, preferably 1000 or less, more preferably 100 or less, still more preferably 10 or less, and particularly preferably 5 or less. The lower limit of the change in surface intrinsic resistance is not particularly limited, but is preferably 0.001 or more, and more preferably 0.1 or more.
The amount of change in the surface intrinsic resistance of the laminated white polyester film can be adjusted by changing the content, type, etc. of the antistatic agent contained in the functional layer.

(Peeling force of functional layer)
As the peeling performance of the functional layer, the peeling force (initial peeling force) from the adhesive tape is usually 3000 mN / cm or less, preferably 2000 mN / cm or less, more preferably 1500 mN / cm or less, more preferably 1200 mN / cm or less, particularly. The range is preferably 1000 mN / cm or less. When the initial peeling force is within the range, the image-forming substance can be easily peeled off. The lower limit is 100 mN / cm or more.

Further, by the measurement method described in the examples described later, the initial peeling force and the peeling force after repeatedly performing the peeling operation three times on the surface of the functional layer (the peeling force after the three peeling operations) are subtracted. The calculated amount of change in peeling force is preferably small, indicating that the strength of the functional layer is high. The upper limit of the amount of change in the peeling force is usually 950 mN / cm or less, more preferably 850 mN / cm or less, still more preferably 700 mN / cm or less, particularly preferably 600 mN / cm or less, and most preferably 500 mN / cm or less. The lower limit of the amount of change in the peeling force is not particularly limited, but is preferably −500 mN / cm or more, and more preferably 0 mN / cm or more.
The amount of change in the peeling force of the laminated white polyester film can be adjusted by changing the content, type and the like of the cross-linking agent contained in the functional layer.

<Manufacturing method of laminated white polyester film>
Hereinafter, a method for producing the present laminated white polyester film will be specifically described. However, the present invention is not particularly limited to the following examples as long as the gist of the present invention is satisfied.

First, a dried or undried mixed raw material is supplied to a melt extruder by a known method, heated to a temperature equal to or higher than the melting point of each polymer, and melt-kneaded. Then, the molten polymer is guided to the die to prepare a molten sheet.
When producing a polyester film laminated in two or more layers, the raw materials blended for each layer are supplied to each melt extruder, heated to a temperature equal to or higher than the melting point of each polymer, and melt-kneaded. The molten polymer in each layer is then guided to the die, usually via a multi-manifold or feed block, and laminated.
Next, the molten sheet extruded from the die is rapidly cooled and solidified on a rotary cooling drum so as to have a temperature equal to or lower than the glass transition temperature to obtain a substantially amorphous unoriented sheet. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and the electrostatic application adhesion method and / or the liquid coating adhesion method is preferably adopted.

The sheet obtained as described above is stretched to form a film. The fine independent cavities contained in the polyester film are created by such stretching.

Specifically describing the stretching conditions, the unstretched sheet is preferably stretched 2.5 to 5 times at 70 to 150 ° C. in the longitudinal direction (longitudinal direction) to obtain a longitudinally uniaxially stretched film. The longitudinally uniaxially stretched film is stretched 3 to 5 times at 70 to 160 ° C. in the width direction (horizontal direction), and is usually in the range of 200 to 250 ° C., preferably 210 to 240 ° C., more preferably 215 to 240 ° C. It is preferable to perform the heat treatment for usually 5 to 600 seconds, preferably 8 to 300 seconds.
By adjusting the heat treatment temperature within such a temperature range, the melt viscosity of the resin incompatible with polyester can be adjusted, and the roughness of the film surface can be adjusted.

The conditions of the heat treatment step affect not only the heat shrinkage rate of the film but also the arithmetic mean roughness (Ra) of the surface of the film. That is, by setting the high temperature in the above range, the fine cavities formed by the polymer incompatible with the polyester existing on the surface are deformed or closed. By appropriately reducing the surface roughness, characters and images formed on the film surface by printing can be easily peeled off and removed. As a result, the film can be repeatedly used as a recording material for copy paper and printer paper.

After the heat treatment step, a method of relaxing 2 to 20% in the vertical direction and / or the horizontal direction in the maximum temperature zone of the heat treatment and / or the cooling zone of the heat treatment outlet is preferable. It is also possible to add re-longitudinal stretching and re-transverse stretching as needed.

[Manufacturing method of functional layer]
The polyester film obtained by the above-mentioned production method has a functional layer laminated on at least one side thereof.
The functional layer can be provided by various known methods such as a coating method, a coextrusion method, and a transfer method. Among them, coating is preferable from the viewpoint of efficient production and performance imparting.

The coating method is, for example, gravure coat, reverse roll coat, die coat, air doctor coat, blade coat, rod coat, bar coat, curtain coat, knife coat, transfer roll coat, squeeze coat, impregnation coat, kiss coat, spray coat. , A conventionally known coating method such as a calendar coat and an extruded coat can be used.
The functional layer may be provided by in-line coating, which treats the film surface during the film forming process of the polyester film, or may adopt offline coating, which is applied outside the system on the film once produced. Above all, the functional layer is more preferably formed by in-line coating.

The in-line coating is a method of coating in the process of manufacturing a polyester film, and specifically, a method of coating at an arbitrary stage from melt extrusion of polyester to stretching, heat fixing and winding. Usually, it is coated on any of an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat fixing, and a film after heat fixing and before winding. Although not limited to the following, for example, in sequential biaxial stretching, a method of coating a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction) and then stretching in the width direction (horizontal direction) is particularly excellent. According to such a method, since the film formation and the functional layer formation can be performed at the same time, there is an advantage in manufacturing cost, and the thickness of the functional layer can be changed by the draw ratio in order to perform stretching after coating. , Thin film coating can be performed more easily than offline coating. Further, by providing the functional layer on the film before stretching, the functional layer can be stretched together with the polyester film, whereby the functional layer can be firmly adhered to the polyester film.
Furthermore, in the production of biaxially stretched polyester film, the film can be restrained in the vertical and horizontal directions by stretching while gripping the end of the film with a clip or the like, and in the heat fixing step, a flat surface without wrinkles or the like. High temperature can be applied while maintaining the sex. Therefore, if in-line coating is applied, the heat treatment applied after coating can be made to a high temperature which cannot be achieved by other methods, so that the film-forming property of the functional layer is improved and the functional layer and the polyester film are made stronger. It can be brought into close contact with each other, and further, by promoting the reaction of the cross-linking agent, a strong functional layer can be obtained. Therefore, the prevention of scraping, the prevention of scratches, and the holding power of various functions of the functional layer are improved.

As a method for forming the functional layer, the polyester film is coated with a solution prepared by using the above-mentioned series of compounds as a solution or a dispersion of a solvent and having a solid content concentration of about 0.1 to 80% by weight as a guide. It is preferable to produce a laminated white polyester film. In particular, when it is provided by in-line coating, it is more preferably an aqueous solution or an aqueous dispersion. The coating liquid may contain a small amount of an organic solvent for the purpose of improving the dispersibility in water, improving the film-forming property, and the like. Further, only one kind of organic solvent may be used, and two or more kinds may be used as appropriate.

The drying and curing conditions for forming the functional layer are not particularly limited, but in the case of the coating method, the drying temperature of the solvent such as water used in the coating liquid is usually 70 to 150 ° C., preferably. Is 80 to 130 ° C, more preferably 90 to 120 ° C. The drying time is, as a guide, 3 to 200 seconds, preferably 5 to 120 seconds.
Further, in order to improve the strength of the functional layer, it is preferable to undergo a heat treatment step in the range of usually 200 to 250 ° C., preferably 210 to 240 ° C., more preferably 215 to 240 ° C. in the film manufacturing process. The time of the heat treatment step is, as a guide, 5 to 600 seconds, preferably 8 to 300 seconds.

Further, if necessary, heat treatment and activation energy ray irradiation such as ultraviolet irradiation may be used in combination. The polyester film constituting the laminated white polyester film may be subjected to surface treatment such as corona treatment and plasma treatment in advance.

<Image forming substance>
In this laminated white polyester film, characters and images containing a thermoplastic resin as an image forming substance can be provided on the functional layer.

Here, characters and images can be provided by a conventionally known method, and can be obtained by printing with a copying machine, a printer, or the like.
On the other hand, conventionally known materials can also be used for the thermoplastic resin used as the image forming substance.
There is no limitation on the image forming substance. That is, the above-mentioned image-forming substance generally includes all substances capable of forming an image with respect to the material to be recorded, and may have any properties such as solid particles, suspensions, and solutions, and ink may also be used. Be included.
Further, there are no restrictions on the colorant, and any of pigments, dyes, colored compounds and the like can be used. Of these, a toner in which a pigment is dispersed in a thermoplastic resin to form fine particles is preferable.

<Resin layer>
In the present laminated white polyester film, a resin layer can be further provided on the image forming substance or the functional layer.
The resin layer may be provided to remove characters and images from the film together with the resin layer in order to reuse the laminated white polyester film and the like.

As the resin layer, a conventionally known material can be used, and a curable layer made of a curable resin composition is preferable.
Examples of the curable resin layer include a thermosetting resin layer made of a resin composition that is cured by heating, an active energy ray-curable resin layer made of a resin composition that is cured by irradiating with active energy rays, and the like. Above all, the active energy ray-curable resin layer is preferable from the viewpoint that it is easy to peel off and remove all characters and images.

Examples of the active energy ray-curable resin layer include an ultraviolet curable resin layer, an electron beam curable resin layer, and a visible light curable resin layer. The UV curable resin layer is preferable in consideration of ease of handling and curable performance. As an example of the active energy ray curable resin layer, for example, a hard coat layer can be mentioned.

The material used for the active energy ray-curable resin layer is not particularly limited. Examples thereof include cured products such as reactive silicon compounds such as monofunctional (meth) acrylate, polyfunctional (meth) acrylate, and tetraethoxysilane. Of these, from the viewpoint of achieving both productivity and hardness, a polymerized cured product of a composition containing an active energy ray-curable (meth) acrylate is particularly preferable. Further, when the resin layer is provided for peeling and removing an image from a laminated white film, it tends to be possible to exhibit good peeling and removing characteristics by using the above-mentioned material.

The composition containing the active energy ray-curable (meth) acrylate is not particularly limited. For example, a mixture of one or more known monofunctional (meth) acrylates, bifunctional (meth) acrylates, and polyfunctional (meth) acrylates, commercially available resin materials for active energy ray-curable hard coats, or these. In addition to this, those to which other components are further added can be used as long as the object of the present embodiment is not impaired.

The active energy ray-curable monofunctional (meth) acrylate is not particularly limited. For example, alkyl (meth) acrylates such as methyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate. Hydroxyalkyl (meth) acrylates such as meth) acrylates, hydroxyethyl (meth) acrylates, hydroxypropyl (meth) acrylates, hydroxybutyl (meth) acrylates, methoxyethyl (meth) acrylates, ethoxyethyl (meth) acrylates, methoxypropyl (meth) acrylates. ) Acrylate alkyl (meth) acrylates such as acrylates and ethoxypropyl (meth) acrylates, aromatic (meth) acrylates such as benzyl (meth) acrylates, phenoxyethyl (meth) acrylates and phenoxypropyl (meth) acrylates, and diaminoethyl (meth). ) Amino group-containing (meth) acrylates such as acrylates and diethylaminoethyl (meth) acrylates, methoxyethylene glycol (meth) acrylates, phenoxypolyethylene grease (meth) acrylates, phenylphenol ethyleneoxide-modified (meth) acrylates and other ethylene oxide modifications. Examples thereof include (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, and (meth) acrylic acid.

The active energy ray-curable bifunctional (meth) acrylate is not particularly limited. For example, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonandiol di (meth) acrylate, tricyclodecandy. Alcandiol di (meth) acrylate such as methylol di (meth) acrylate, bisphenol-modified di (meth) acrylate such as bisphenol A ethylene oxide-modified di (meth) acrylate, bisphenol F ethylene oxide-modified di (meth) acrylate, polyethylene glycol di. Examples thereof include (meth) acrylate, polypropylene glycol di (meth) acrylate, urethane di (meth) acrylate, and epoxy di (meth) acrylate.

The active energy ray-curable polyfunctional (meth) acrylate is not particularly limited, and is, for example, dipentaerythritol hexa (meth) acrylate, pentaerythritol tetra (meth) acrylate, and ditrimethylolpropane tetra (meth) acrylate. , Pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, isocyanuric acid ethylene oxide-modified tri (meth) acrylate, ε-caprolactone-modified tris (acroxyethyl) isocyanurate-modified tri (meth) Examples thereof include acrylate, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer and the like.

Among these, one or more (meth) acrylates are preferable from the group consisting of hydroxyalkyl-based (meth) acrylates, aromatic (meth) acrylates, and alkyl glycol-based (meth) acrylates.
By including hydroxyalkyl-based, aromatic-based, and alkylglycol-based in the (meth) acrylate, the adhesion to the image-forming substance is improved, and not only is it easy to peel off and remove, but also the laminated white used as the recording material is used. Damage to the polyester film is suppressed, and it can be recycled. On the other hand, if the (meth) acrylate does not contain the above-mentioned component, the adhesion to the image-forming substance is lowered, and the image-forming substance may not be removed well.
Hydroxyalkyl-based (meth) acrylates include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and 1,4-cyclohexanedi. Examples thereof include methanol monoacrylate, neopentyl glycol di (meth) acrylate of hydroxybivariate, and glycerol (meth) acrylate.
Examples of the aromatic (meth) acrylate include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, and phenoxypropyl (meth) acrylate.
Examples of the alkyl glycol-based (meth) acrylate include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and polypropylene glycol di (meth) acrylate.

The other components contained in the composition containing the active energy ray-curable (meth) acrylate are not particularly limited. Examples thereof include inorganic or organic fine particles, polymerization initiators, polymerization inhibitors, antioxidants, antistatic agents, dispersants, surfactants, light stabilizers and leveling agents. Further, in the case of drying after forming a film in the wet coating method, an arbitrary amount of solvent can be added.

When the resin layer is provided for peeling and removing characters and images from the laminated white film, the peeling and removing step is usually performed in an office or the like, not in a factory where the film is manufactured. Therefore, it is preferable not to contain a solvent for indoor use such as an office. As the resin (resin liquid) for forming the resin layer, the content of the solvent is preferably 10% by weight or less, more preferably 5% by weight or less, still more preferably 3% by weight or less, and particularly preferably 1% by weight or less. Most preferably, it does not contain a solvent (intentionally does not contain it).

Examples of the method for forming the resin layer include a general wet coating method such as a roll coating method and a die coating method, and an extrusion method. The formed resin layer can be heated or irradiated with active energy rays such as ultraviolet rays and electron beams as needed to carry out a curing reaction.

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. The measurement method used in the present invention is as follows. The various physical properties in the present invention, their measurement methods, and their definitions are as follows.

<Measurement method>
(1) Intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed is precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added and dissolved. , Measured at 30 ° C.

(2) Melt flow index (MFI)
Amorphous polyolefin was measured at 275 ° C. and 21.2N and polypropylene was measured at 230 ° C. and 21.2N according to JIS K7210-1995. The higher this value, the lower the melt viscosity of the polymer.

(3) Arithmetic mean roughness (Ra)
Non-contact surface / layer cross-sectional shape measurement system V manufactured by Ryoka System Co., Ltd. on the film surface
Using ertScan (registered trademark) R550GML, CCD camera: SONY HR-50 1/3', objective lens: 20x, lens barrel: 1X Body, zoom lens: No Release, wavelength filter: 530 white, measurement mode: A region of 640 μm × 480 μm was measured by Wave, and the arithmetic mean roughness Ra value was obtained by averaging 10 points using the output by the fourth-order polymorphic correction.

(4) Average particle size of particles The size of particles was measured by the sedimentation method based on Stokes's resistance law using a centrifugal sedimentation type particle size distribution measuring device SA-CP3 manufactured by Shimadzu Corporation. The average particle size was taken using the value of 50% of the integrated (volume basis) in the equivalent spherical distribution of the particles obtained by the measurement.

(5) Film thickness of the functional layer The surface of the functional layer was dyed with _RuO4 and embedded in an epoxy resin. Then, the section prepared by the ultramicrotomy method is stained with _RuO4 , the cross section of the functional layer is observed using a transmission electron microscope (H-7650 manufactured by Hitachi High-Technologies Corporation, acceleration voltage 100 kV), and the film thickness is measured. bottom.

(6) Number average molecular weight Measured using gel permeation chromatography (HLC-8120GPC manufactured by Tosoh Corporation). The number average molecular weight was calculated in terms of polystyrene.

(7) Heat shrinkage rate The sample was treated in an oven kept at 150 ° C. in a non-tensioned state for 30 minutes, the length of the sample before and after that was measured, and the heat shrinkage rate was calculated by the following formula.
Heat shrinkage rate (%) = {(L0-L1) / L0} × 100
(In the above formula, L0 is the sample length before the heat treatment, and L1 is the sample length after the heat treatment).
Five points were measured in the longitudinal direction (MD) and the width direction (TD) of the film, and the average value in each direction was calculated.

(8) Hunter whiteness Using a colorimeter NDH-1001DP (C light source, 2 ° field) manufactured by Nippon Denshoku Industries Co., Ltd., according to the method of JIS P8123-1961, the hunter whiteness when a single film is used (8) Wb) was measured. The back surface of the film was pressed with a black plate.

(9) b value (reflection method)
Using a colorimeter NDH-1001DP (C light source, 2 ° field) manufactured by Nippon Denshoku Industries Co., Ltd., the b value of a single film was measured according to the method of JIS Z-8722, 8730. The back surface of the film was pressed with a black plate.

(10) Concealment degree (OD)
A Macbeth densitometer TD-904 was used to measure the transmitted density by white light. Five points were measured, and the average value was taken as the OD value. The larger this value is, the lower the light transmittance is.

(11) Apparent density (g / cm ³ )
A 10 cm × 10 cm square sample was cut out from an arbitrary part of the film, and the thickness was measured evenly at 9 points with a micrometer. The weight per unit volume was calculated from the average value and the weight of the film, and used as the apparent density. The number of measurements was 5 points, and the average value was used.

(12) Thickness of Laminated White Polyester Film A small piece of film was fixedly molded with an epoxy resin, cut with a microtome, and the cross section of the film was observed by a transmission electron micrograph. Two of the cross sections are almost parallel to the film surface, and the interface is observed by light and dark. The distance between the two interfaces and the film surface was measured from 10 photographs, and the average value was taken as the thickness of the laminated white polyester film.

(13) Method for measuring the content of the third component Dissolve polyester in a mixed solvent of deuterated chloroform / hexafluoroisopropanol (weight ratio 7/3) and use NMR (JNM-EX270 type manufactured by JEOL Ltd.). Each peak of 1H-NMR was assigned, and the content of the third component was calculated from the integrated value of the peaks. In addition, the total content of each component (copolymerized polyester) was calculated.

(14) Appropriate image quality by electrophotographic printing Ricoh Co., Ltd. multifunction device: A4 size cut film (sheet) is fed into imagioMPC5001it, and a full-color test image on which an image forming substance by photographic printing is placed is printed. Obtained. The image quality was evaluated as follows.

(Evaluation criteria)
A: High-definition, high-quality image quality without wrinkles on the film B: Part of the image quality is slightly unclear, but there is no problem in practical use C: Wrinkles are generated on the film, and the image quality is also unclear and overall. Inferior.

(15) Characters, images (toner image)
95 parts by weight of an ultraviolet curable resin (2-hydroxy-3-phenoxypropyl acrylate), a photopolymerization initiator (trade name: Irgacure 184), was applied to the surface of the film on which the image-forming substance obtained by the proper peeling removal (14) was fixed. , Ciba Specialty Chemicals Co., Ltd.) A mixture consisting of 5 parts by weight was uniformly applied, a glass plate was placed on the mixture, and ultraviolet rays were irradiated from above the mixture to form an ultraviolet curable resin layer. Then, the glass plate and the film were peeled off. At this time, the formed ultraviolet curable resin layer adheres to the glass plate side, and characters and images formed on the film surface by an image forming substance or the like can be transferred and retained. The following evaluation was performed on the state of removing character / image peeling on the film surface at this time.

(Evaluation criteria)
A: The image-forming substance on the film surface can be completely removed, and it can be used repeatedly as copying paper.
B: Although a small amount of image-forming substance remains on the film surface, it can be used repeatedly as copying paper, and there is no practical problem.
C: Most of the image-forming substance remains on the film surface, and it cannot be used repeatedly as copy paper.

(16) Print transportability Ricoh Co., Ltd. Multifunction device: A film of a multifunction device when 100 sheets of film (sheet) cut into A4 size are fed into the imagioMPC5001it and 100 sheets are continuously printed by photographic printing. (Sheet) Transportability was evaluated as follows.

(Evaluation criteria)
A: There is no film (sheet) clogging in the compound machine. In addition, it was confirmed on the paper discharge stand of the multifunction device that the printed film (sheet) could be transported independently without any double feeding.
B: Double feeding of the printed film (sheet) sometimes occurs, but it is confirmed on the paper ejection board of the multifunction device that continuous printing was possible without jamming of the film (sheet) in the multifunction device within the range where there is no practical problem. ..
C: Since several sheets of film are agglomerated by sticking the films (sheets) to each other, the multifunction device cannot convey the film (sheet), or the film (sheet) is often clogged in the multifunction device for continuous printing. The image quality is unclear and overall inferior even if it cannot be printed or can be printed barely.

(17) Writability With a pencil of uni hardness H manufactured by Mitsubishi Pencil Co., Ltd., five straight lines were drawn at 1 mm intervals, and the following evaluation was performed visually.

(Evaluation criteria)
A: Individual straight lines can be discriminated.
B: The color of the lines is light and it is difficult to distinguish individual lines.
C: I can't draw a straight line.

(18) Appearance of functional layer The laminated white polyester film was observed under a fluorescent lamp, and the appearance of the functional layer was visually evaluated as follows.

(Evaluation criteria)
A: Uniform appearance with no defects in the functional layer B: Defects are seen in a part of the functional layer C: Defects are seen in most of the functional layer

(19) Peeling force of functional layer (initial peeling force)
An adhesive tape (“No. 31B” substrate thickness 25 μm manufactured by Nitto Denko Corporation) was pressure-bonded to the surface of the functional layer once with a 2 kg rubber roller with a width of 5 cm, and the peeling force after being left at room temperature for 1 hour was measured. As the peeling force, "Ezgraph" manufactured by Shimadzu Corporation was used, and 180 ° peeling was performed under the condition of a tensile speed of 300 mm / min, and the peeling force (initial peeling force) was measured.

(20) Peeling force after three peeling operations of the functional layer 95 parts by weight of an ultraviolet curable resin (2-hydroxy-3-phenoxypropyl acrylate) on the surface of the functional layer, a photopolymerization initiator (trade name: Irgacure 184, Ciba) (Manufactured by Specialty Chemicals Co., Ltd.) A mixture consisting of 5 parts by weight is uniformly applied, a glass plate is placed on the mixture, ultraviolet rays are irradiated from above the mixture to form an ultraviolet curable resin layer, and then the glass plate and the film are formed. The UV-curable resin layer formed by peeling was adhered to the glass plate side. Regarding the peeling force of the functional layer after repeating this operation three times on the surface of the functional layer, an adhesive tape (“No. 31B” base material thickness 25 μm manufactured by Nitto Denko Corporation) was applied to the surface of the functional layer in a width of 5 cm and 2 kg. The peeling force was measured after one reciprocating crimping with a rubber roller and leaving at room temperature for 1 hour. As the peeling force, "Ezgraph" manufactured by Shimadzu Corporation was used, and 180 ° peeling was performed under the condition of a tensile speed of 300 mm / min, and the peeling force after three peeling operations was measured.

(21) Initial surface specific resistance value of the functional layer Using a high resistance measuring instrument: HP4339B and a measuring electrode: HP16008B manufactured by Nippon Hulett Packard, the polyester film is sufficiently adjusted under a measuring atmosphere of 23 ° C. and 50% RH. After wetting, the surface intrinsic resistance value of the functional layer after 1 minute was measured at an applied voltage of 100 V.

(22) Surface intrinsic resistance value after three peeling operations of the functional layer 95 parts by weight of an ultraviolet curable resin (2-hydroxy-3-phenoxypropyl acrylate) on the surface of the functional layer, a photopolymerization initiator (trade name: Irgacure 184) , Ciba Specialty Chemicals Co., Ltd.) Uniformly coat a mixture consisting of 5 parts by weight, place a glass plate on the mixture, irradiate it with ultraviolet rays to form an ultraviolet curable resin layer, and then use it as a glass plate. The film was peeled off, and the formed ultraviolet curable resin layer was adhered to the glass plate side. After repeating this operation three times on the surface of the functional layer, the surface specific resistance value of the functional layer was measured at 23 ° C. using a high resistance measuring instrument: HP4339B and a measuring electrode: HP16008B manufactured by Hulett Packard Japan. After sufficiently adjusting the humidity of the polyester film under a measurement atmosphere of 50% RH, the surface specific resistance value of the functional layer after 1 minute was measured at an applied voltage of 100 V.

The laminated white polyester films of Examples 1 to 26 and Comparative Example 1 were prepared as follows.

<Functional layer>
The compounds constituting the functional layer are as follows.

-Crosslinking agent (hexamethoxymethylol melamine): (IA)

-Crosslinking agent (oxazoline compound): (IB)
Acrylic polymer with oxazoline group and polyalkylene oxide chain Epocross (registered trademark) (Oxazoline group amount = 4.5 mmol / g, manufactured by Nippon Shokubai Co., Ltd.)

-Crosslinking agent (isocyanate compound): (IC)
1000 parts by weight of hexamethylene diisocyanate was stirred at 60 ° C., and 0.1 part by weight of tetramethylammonium caprylate was added as a catalyst. After 4 hours, 0.2 part by weight of phosphoric acid was added to stop the reaction, and an isocyanurate-type polyisocyanate composition was obtained. 100 parts by weight of the obtained isocyanurate-type polyisocyanate composition, 42.3 parts by weight of methoxypolyethylene glycol having a number average molecular weight of 400, and 29.5 parts by weight of propylene glycol monomethyl ether acetate were charged and held at 80 ° C. for 7 hours. After that, the reaction solution temperature was maintained at 60 ° C., 35.8 parts by weight of methyl isobutanoyl acetate, 32.2 parts by weight of diethyl malonate, and 0.88 parts by weight of a 28% by weight methanol solution of sodium methoxide were added, and the mixture was held for 4 hours. bottom. A blocked polyisocyanate with active methylene obtained by adding 58.9 parts by weight of n-butanol, holding at a reaction solution temperature of 80 ° C. for 2 hours, and then adding 0.86 parts by weight of 2-ethylhexyl acid phosphate.

-Antistatic agent (compound having an ammonium group): (II)
A polymer polymerized with the following composition having a pyrrolidinium ring in the main chain, diallyldimethylammonium chloride / dimethylacrylamide / N-methylolacrylamide = 90/5/5 (mol%). Number average molecular weight 30,000.

-Release agent (long-chain alkyl group-containing compound): (III)
200 parts by weight of xylene and 600 parts by weight of octadecyl isocyanate were added to the four-necked flask and heated under stirring. From the time when xylene began to reflux, 100 parts by weight of polyvinyl alcohol having an average degree of polymerization of 500 and a saponification degree of 88 mol% was added little by little at 10 minute intervals for about 2 hours. After the addition of polyvinyl alcohol was completed, reflux was carried out for another 2 hours to complete the reaction. When the reaction mixture was cooled to about 80 ° C. and then added to methanol, the reaction product precipitated as a white precipitate. This precipitate was filtered off, 140 parts by weight of xylene was added, and the mixture was heated to completely dissolve. After repeating the operation of adding methanol again to precipitate the precipitate, the precipitate was washed with methanol and dried and pulverized to obtain the precipitate.

・ Acrylic resin: (IV)
Emulsified polymer of ethyl acrylate / n-butyl acrylate / N-methylolacrylamide / acrylic acid = 88/10/1/1 (% by weight) (emulsifier: nonionic surfactant)

[Example 1]
For the intermediate layer, 80 parts by weight of a polyethylene terephthalate chip (containing 2 mol% of diethylene glycol) having an intrinsic viscosity of 0.67 dl / g and 20 parts by weight of a crystalline polypropylene homopolymer chip having a melt flow index of 10 ml / 10 minutes at 280 ° C. It was sent to the main twin-screw extruder with vent set in.
A crystalline polypropylene homopolymer containing 50% by weight of titanium oxide particles having an average particle size of 0.32 μm for the surface layer, 15 parts by weight of a polyethylene terephthalate chip having an intrinsic viscosity of 0.66 dl / g, and a melt flow index of 8 ml / 10 minutes. Polyethylene terephthalate with an intrinsic viscosity of 0.66 dl / g containing 3.5% by weight of silica particles with an average particle size of 4.1 μm and 15 parts by weight of the chip. Polyethylene terephthalate with an intrinsic viscosity of 0.69 dl / g. 60 parts by weight of the chips (containing 2 mol% of diethylene glycol) were fed into a sub-vented twin-screw extruder set at 280 ° C.
Through the gear pump and filter, the polymer from the main extruder is the intermediate layer, and the polymer from the sub extruder is the surface layer on both sides of the intermediate layer. It was extruded and extruded from the base, and rapidly cooled and solidified on a cooling roll having a surface temperature set to 30 ° C. using an electrostatic application adhesion method to obtain a substantially amorphous sheet having a thickness of 887 μm.

After the obtained amorphous sheet was stretched 3.1 times in the vertical direction at 92 ° C., the aqueous coating liquid A1 shown in Table 1 below was applied to both sides of the vertically stretched film to form the functional layer film thickness (after drying). Is applied so that A laminated white polyester film having a thickness structure of (surface layer) / 62 μm (intermediate layer) / 6 μm (surface layer) and having a total thickness of 74 μm was obtained.
When the obtained laminated white polyester film was evaluated, the amount of change in the peeling force due to the three-time peeling was small, and there was no change in the surface intrinsic resistance, and the film was good. The characteristics of this film are shown in Tables 2 and 3 below.

[Examples 2 to 14]
A laminated white polyester film was obtained in the same manner as in Example 1 except that the composition of the coating liquid for the functional layer was changed as shown in Table 1. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 15]
40 parts by weight of polyethylene terephthalate chip (containing 2 mol% of diethylene glycol) having an intrinsic viscosity of 0.63 dl / g, 15 parts by weight of crystalline polypropylene homopolymer chip having a melt flow index of 7 ml / 10 minutes, polyester production of Example 1. The intermediate layer was made by using a mixed raw material in which the recycled products from the ears and master roll ears that were occasionally generated were mixed at a ratio of 45% by weight, and the coating liquid was used instead of the aqueous coating liquid A1 shown in Table 1 below. A laminated white polyester film having a thickness of 75 μm was obtained in the same manner as in Example 1 except that A8 was applied. The thickness of each layer of the obtained film was 6 μm / 63 μm / 6 μm. The total amount of polypropylene derived from the crystalline polypropylene homopolymer chip and the recycled product is 24% by weight. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 16]
A laminated white polyester film having a thickness of 75 μm was obtained in the same manner as in Example 15 except that the coating liquid A12 was applied instead of the water-based coating liquid A8 shown in Table 1 below. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 17]
Polyester production according to Example 1, 3 parts by weight of polyethylene terephthalate chip having an intrinsic viscosity of 0.66 dl / g (containing 2 mol% of diethylene glycol), 10 parts by weight of crystalline polypropylene homopolymer chip having a melt flow index of 10 ml / 10 minutes. The intermediate layer was made by using a mixed raw material in which the recycled products from the ears and master roll ears that were occasionally generated were mixed at a ratio of 87% by weight, and the coating liquid was used instead of the aqueous coating liquid A1 shown in Table 1 below. A laminated white polyester film having a thickness of 75 μm was obtained in the same manner as in Example 1 except that A8 was applied. The thickness of each layer of the obtained film was 6 μm / 63 μm / 6 μm. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 18]
A laminated white polyester film having a thickness of 75 μm was obtained in the same manner as in Example 17 except that the coating liquid A12 was applied instead of the water-based coating liquid A8 shown in Table 1 below. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 19]
1. 15 parts by weight of polyethylene terephthalate chip having an intrinsic viscosity of 0.65 dl / g containing 50% by weight of titanium oxide particles having an average particle size of 0.32 μm, and a crystalline polypropylene homopolymer chip having a melt flow index of 8 ml / 10 minutes. Polyethylene terephthalate chip with an intrinsic viscosity of 0.66 dl / g containing 0.5% by weight of silica particles with an average particle size of 4.1 μm and 3 parts by weight. Polyester with an intrinsic viscosity of 0.68 dl / g. A laminated white polyester film having a thickness of 75 μm was obtained in the same manner as in Example 15 except that 82.1 parts by weight of a terephthalate chip (containing 2 mol% of diethylene glycol) was used as the surface layer. The thickness of each layer of the obtained film was 6 μm / 63 μm / 6 μm. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 20]
A laminated white polyester film having a thickness of 75 μm was obtained in the same manner as in Example 19 except that the coating liquid A12 was applied instead of the water-based coating liquid A8 shown in Table 1 below. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 21]
15 parts by weight of polyethylene terephthalate chip having an intrinsic viscosity of 0.66 dl / g and 15 parts by weight of crystalline polypropylene homopolymer chip having a melt flow index of 8 ml / 10 minutes containing 50% by weight of titanium oxide particles having an average particle size of 0.12 μm. 10 parts by weight of a polyethylene terephthalate chip having an intrinsic viscosity of 0.66 dl / g and a polyethylene terephthalate chip having an intrinsic viscosity of 0.69 dl / g (diethylene glycol) containing 3.5% by weight of silica particles having an average particle size of 4.1 μm. A laminated white polyester film having a thickness of 75 μm was obtained in the same manner as in Example 15 except that 60 parts by weight (containing 2 mol%) was used as the surface layer. The thickness of each layer of the obtained film was 6 μm / 63 μm / 6 μm. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 22]
A laminated white polyester film having a thickness of 75 μm was obtained in the same manner as in Example 21 except that the coating liquid A12 was applied instead of the water-based coating liquid A8 shown in Table 1 below. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 23]
15 parts by weight of polyethylene terephthalate chip having an intrinsic viscosity of 0.66 dl / g and 15 parts by weight of crystalline polypropylene homopolymer chip having a melt flow index of 8 ml / 10 minutes containing 50% by weight of titanium oxide particles having an average particle size of 0.32 μm. The same as in Example 15 except that 70 parts by weight of a polyethylene terephthalate chip having an intrinsic viscosity of 0.66 dl / g containing 5.0% by weight of silica particles having an average particle size of 11.1 μm was used as a surface layer. A laminated white polyester film having a thickness of 75 μm was obtained. The thickness of each layer of the obtained film was 6 μm / 63 μm / 6 μm. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 24]
A laminated white polyester film having a thickness of 75 μm was obtained in the same manner as in Example 23 except that the coating liquid A12 was applied instead of the water-based coating liquid A8 shown in Table 1 below. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 25]
In the heat treatment step in the film forming step, a laminated white polyester film having a thickness of 75 μm and a thickness of each layer of 6 μm / 63 μm / 6 μm was obtained in the same manner as in Example 15 except that the heat treatment temperature was set to 201 ° C. for 10 seconds. Obtained. The characteristics of this film are shown in Tables 2 and 3 below.

[Example 26]
A laminated white polyester film having a thickness of 75 μm was obtained in the same manner as in Example 25 except that the coating liquid A12 was applied instead of the water-based coating liquid A8 shown in Table 1 below. The characteristics of this film are shown in Tables 2 and 3 below.

[Comparative Example 1]
A polyester film was obtained in the same manner as in Example 1 except that the composition of the coating liquid for the functional layer was changed as shown in Table 1. The characteristics of this film are shown in Tables 2 and 3 below.
Since the coating liquid of the functional layer did not contain a cross-linking agent, the amount of change in peeling force was large, the amount of change in surface intrinsic resistance was large, and the strength of the functional layer was weak.

Claims (10)

A laminated white polyester film having a functional layer on at least one side of a polyester film containing polyester as a main component resin and containing a polymer incompatible with the polyester.
The functional layer contains a mold release agent composed of a long-chain alkyl group-containing compound, a cross-linking agent, and an antistatic agent, and has a peeling force and an initial peeling force after three peeling operations measured in the next test. A laminated white polyester film having a peeling force change amount of 950 mN / cm or less, which is the difference between the two.
Initial peeling force test: Adhesive tape is pressure-bonded to the surface of the functional layer of the laminated film once with a 2 kg rubber roller with a width of 5 cm, left at room temperature for 1 hour, and then peeled 180 ° under the condition of a tensile speed of 300 mm / min. Measure the peeling force.
Peeling force test after 3 peeling operations: A mixture consisting of 95 parts by weight of an ultraviolet curable resin (2-hydroxy-3-phenoxypropyl acrylate) and 5 parts by weight of a photopolymerization initiator is applied to the surface of the functional layer of the laminated film. A glass plate is placed on the mixture, and ultraviolet rays are irradiated from above to form an ultraviolet curable resin layer. Then, the glass plate and the laminated film are peeled off, and the formed ultraviolet curable resin layer is adhered to the glass plate side. After repeating the operation of the functional layer three times on the surface of the functional layer, the adhesive tape was pressure-bonded to the surface of the functional layer once with a 2 kg rubber roller with a width of 5 cm, left at room temperature for 1 hour, and then the tensile speed was 300 mm / min. 180 ° peeling is performed under the above conditions, and the peeling force is measured after the peeling operation three times. The laminated white polyester film according to claim 1, wherein the functional layer is a recorded layer. The laminated white polyester film according to claim 1 or 2, wherein the polyester film has a multilayer structure of two or more layers. The laminated white polyester film according to claim 3, wherein at least one surface layer of the polyester film contains a polymer incompatible with polyester. The laminated white polyester film according to claim 4, wherein the layer other than the surface layer of the polyester film contains a polymer incompatible with polyester. The laminated white polyester film according to any one of claims 1 to 5, wherein the polyester film contains metal compound particles. The laminated white polyester film according to any one of claims 1 to 6, wherein the polyester film contains particles other than metal compound particles. The method according to any one of claims 1 to 7, wherein the polyester film with a functional layer having the functional layer on at least one side of the polyester film has a heat shrinkage rate of 2.8% or less after heating at 150 ° C. for 30 minutes. Laminated white polyester film. The laminated white polyester film according to any one of claims 1 to 8, wherein the polyester film with a functional layer having the functional layer on at least one side of the polyester film has a hiding power (OD) of 0.30 or more. The recorded image is provided on the functional layer of the laminated white polyester film according to any one of claims 1 to 9, and a resin layer which is an active energy ray-curable resin layer is provided on the image-forming substance. Material manufacturing method.