KR102689393B1 - polyester film - Google Patents

Abstract

It relates to a polyester film that has a roughened film surface and is used for transferring the surface state, wherein the visibility of the polyester film during transfer, in other words, the discrimination, is excellent, and even if a release layer is formed, the above A new polyester film is provided that can impart the expected matte feeling to an object without the roughening state being smoothed. A polyester film comprising a particle-containing layer containing particles with an average particle diameter of 2.0 ㎛ or more, comprising forming a release layer on the surface of the particle-containing layer of a polyester film base, and having a transmission density OD value of 0.10 or more. I suggest.

Description

polyester film

The present invention relates to a polyester film capable of transferring a matte appearance and having mold release performance.

Polyester films, represented by polyethylene terephthalate and polyethylene naphthalate, have excellent properties such as mechanical strength, dimensional stability, flatness, heat resistance, chemical resistance, and optical properties, and have excellent cost performance, so they are used for various purposes.

An example of the use of the polyester film is as an electromagnetic wave shield. In plasma displays (PDPs), etc., an electromagnetic wave shielding film, that is, a conductive film, is attached to the front of the display panel. As this electromagnetic wave shielding film, a polyester film is made of mesh-like metal. Conductive films provided with thin wires are generally used.

As an electromagnetic wave shield film of this type, an electromagnetic wave shield film is formed on a support film, and the electromagnetic wave shield film is transferred by hot press-bonding it to the surface of various devices.

As a support film for such a transfer-type electromagnetic wave shield film, a flat polyester film has conventionally been generally used. However, in order to finish the exterior of the product by matting it, it has been proposed to use a polyester film with a matte surface as the support film and to transfer this matte surface to the product.

For example, in Patent Document 1, a base film having a polyester A layer as the outermost layer containing 0.1% by mass or more and 10% by mass or less of inorganic particles and/or organic particles, with the entire polyester A layer being 100% by mass. A biaxially oriented polyester film for release is disclosed, which is formed by laminating a coating layer containing melamine resin as a main component on layer A, and having a glossiness of 30 or less on the surface on which the coating layer is laminated.

Patent Document 2 discloses a laminated polyester film having a base material layer and a matting layer containing particles on at least one surface, wherein the average surface roughness (Ra) of the surface of the matting layer is 400 to 1000 nm, 10 points. Biaxially oriented poly, characterized in that the average roughness (Rz) is 4000 to 8000 nm, the glossiness (G60) on the surface is 6 to 20, and the void destruction rate of the surface projections is 20% or less. An ester film is disclosed.

Patent Document 3 has a polyester A layer containing inorganic particles and/or organic particles as at least one outermost layer, and the average surface roughness Ra of the surface of the polyester A layer of the outermost layer is 0.38 μm or more and 1.0 μm or less. , a biaxially oriented polyester film for mold release in which the average length RSm of the roughness curve elements on the surface of the polyester A layer is 10 μm or more and 80 μm or less is disclosed.

Japanese Patent Laid-Open No. 2015-66805 Japanese Patent Laid-Open No. 2016-97522 Japanese Patent Laid-Open No. 2016-175229

As described above, the surface of the polyester film is roughened to form a matte surface, the surface of the polyester film is pressed against the surface of the object, and then the polyester film is peeled off. , the roughened surface state can be transferred to the surface of the object and finished with a matte appearance.

In the conventionally proposed polyester film for transfer of this type, it was necessary to form a separate release layer by laminating a release film on the surface of the polyester film or applying a release agent, so a release layer was formed. In some cases, the roughening state of the polyester film surface was smoothed, making it impossible to provide the expected matte feel to the surface of the object.

Moreover, as a polyester film with mold release performance, it was expected that it would be excellent in visibility, in other words, in distinguishability.

Therefore, the first object of the present invention relates to a polyester film that has a roughened film surface and is used for transferring the surface state, and the visibility of the polyester film during transfer, in other words, is excellent in identification, Furthermore, the object is to provide a new polyester film that can impart the expected matte feel to an object without smoothing the roughening state even if a release layer is formed.

The second object of the present invention is to provide a new polyester film that prevents curling of the entire polyester film, improves handling properties, and further improves adhesion to products on which the polyester film is laminated. It is about providing.

In order to achieve the first object, the present invention has a polyester film base material having a particle-containing layer containing particles with an average particle diameter of 2.0 ㎛ or more, and has a transmission density OD value of 0.25 or more. proposes.

In order to achieve the first object, the present invention also provides a structure in which a release layer is formed on the surface of the particle-containing layer of a polyester film base containing particles with an average particle size of 2.0 ㎛ or more, , we propose a second polyester film characterized by a transmission density OD value of 0.10 or more.

In order to achieve the second object, the present invention is provided with a particle-containing layer A containing particles with an average particle diameter of 2.0 ㎛ or more on one side of the base layer, and on the other side of the base layer, the average particle-containing layer A is provided. A third polyester film having a polyester film base material provided with a particle-containing layer B containing particles with a particle diameter of 2.0 μm or more, wherein the content of particles with an average particle size of 2.0 μm or more is lower in the particle-containing layer B than in the particle-containing layer A. proposes.

Since the first and second polyester films proposed by the present invention can be provided with a release layer, when the release layer is formed, the roughening state of the polyester film surface is not smoothed and the expected mat is not achieved. Persimmon can be given to an object. In addition, since the transmission density OD value of the polyester film is 0.10 or more or 0.25 or more, the visibility of the polyester film during transfer, in other words, the discriminability, is excellent.

The third polyester film proposed by the present invention has a polyester film base material having particle-containing layers A and B on both sides of the base layer, and the content of particles with an average particle diameter of 2.0 ㎛ or more is greater in the particle-containing layer B than in the particle-containing layer A. The polyester film, which is characterized by a small amount, has particle-containing layers A and B on both sides of the base layer, and thus can prevent curling of the entire polyester film. Furthermore, while providing a matte feeling to the surface of the object on the surface side of the particle-containing layer A, by making the particle content of the particle-containing layer B smaller than that of the particle-containing layer A, surface processing suitability can be secured, and the surface of the particle-containing layer B Since the desired layer can be easily laminated, for example, adhesion to the product to be laminated can be improved.

1 is a cross-sectional view showing a configuration example of a polyester film according to an example of an embodiment of the present invention.

Next, the present invention will be explained based on embodiment examples. However, the present invention is not limited to the embodiments described below.

<< This polyester film 1 >>

The polyester film (referred to as “this polyester film 1”) according to an example of the embodiment of the present invention is a polyester film provided with a particle-containing layer A containing particles with an average particle diameter of 2.0 μm or more.

This polyester film 1 may be an unstretched film (sheet) or a stretched film. Among these, a stretched film stretched in a uniaxial direction or a biaxial direction is preferable. Among them, a biaxially stretched film is preferable because it is excellent in the balance of mechanical properties and planarity.

This polyester film 1 may be composed solely of a polyester film provided with a particle-containing layer A containing particles with an average particle diameter of 2.0 μm or more, or may be composed of other layers laminated on the polyester film.

<< This polyester film 10 >>

A polyester film (referred to as “this polyester film 10”) according to another example of an embodiment of the present invention is a polyester film having a structure in which a release layer is formed on one side or both sides of a polyester film base material. am.

As a lamination configuration of the present polyester film 10, a release layer may be formed on one side of the polyester film base, the other side may be configured to leave the surface of the polyester film base as it is, and another layer may be formed on the other side. It may be a configuration formed by forming . In addition, a structure formed by forming a release layer on both sides of the polyester film base material may be used.

Additionally, other layers may be provided between the polyester film substrate and the release layer.

However, it is preferable that the release layer is at least one of the outermost surfaces.

< Polyester film base material >

The polyester film substrate is preferably provided with a particle-containing layer A containing particles with an average particle diameter of 2.0 μm or more. That is, it is preferable to use the present polyester film 1 as a polyester film base material. Therefore, the following description of the polyester film base is also a description of the present polyester film 1.

The composition of the polyester film base may be composed of only the particle-containing layer A, or may be provided with the particle-containing layer A on one side or both sides of the base layer. As a specific example of the latter, for example, a particle-containing layer A may be provided on both sides of the base layer, or a particle-containing layer A may be provided on one side of the base layer, and a particle-containing layer A may be provided on the other side of the base layer. A particle-containing layer B different from It may be provided, and a layer containing no particles may be formed on the other side of the base layer.

Among them, the polyester film base material preferably has a structure in which the particle-containing layer A is provided on one side of the base layer, and the particle-containing layer B, which is different from the particle-containing layer A, is formed on the other side of the base layer. This structure will be described in detail later. do.

The polyester film base material preferably has a transmission density OD value of 0.10 or more.

A transmission density OD value of 0.10 or more means that the opacity is high, or in other words, the whiteness is high, and the whiteness is higher.

From this viewpoint, it is more preferable that it is 0.10 to 1.0, especially 0.15 or more or 0.90 or less, especially 0.20 or more or 0.80 or less, and especially 0.25 or more.

When the transmission density OD value of the polyester film base material is within the above range, visibility, or in other words, discriminability, is good, so it becomes easy to peel off the present polyester film 10 after transferring the rough surface to the transfer object.

Methods for increasing the transmission density OD value of the polyester film base material to 0.10 or more include adding a white pigment, containing a material with a large difference in refractive index from the main component resin of the base material, or stretching a film containing fine particles. It is possible to employ known methods, such as forming voids in the film substrate.

Among them, when whitening is achieved by containing a white pigment, for example, metal compound particles, for example, the base layer, the particle-containing layer, and a layer provided on the opposite side of the base layer from the particle-containing layer. Whitening can be achieved by containing metal compound particles in any of the layers or in two or more of them. At this time, examples of the white pigment include particles Y with an average particle diameter of less than 2.0 μm, which will be described later.

In addition, it is natural that the transmission density OD value of this polyester film 10 is lower than the transmission density OD value of the polyester film base material.

(Polyester as the main component resin of each layer)

The layers constituting the polyester film substrate, for example, the above-described substrate layer, particle-containing layer A, particle-containing layer B, and additional other layers, are preferably layers containing polyester as the main component resin.

Here, “main component resin” means the resin with the highest content rate among the resin components constituting each layer.

The polyester may be obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol.

Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalene dicarboxylic acid, and examples of the other aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexane. Dimethanol, etc. can be mentioned.

In addition, the polyester may be homopolyester or copolyester. As the dicarboxylic acid component of this copolymerized polyester, for example, one or two types selected from isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid. The above can be mentioned, and as the other glycol component, for example, one or two or more types selected from ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, etc. can be mentioned. From the viewpoint of effectively imparting a matte feel, it is preferable that the third component contained is isophthalic acid.

In the copolymerized polyester, the third component contained is preferably 30 mol% or less, especially 5 mol% or more or 30 mol% or less, especially 25 mol% or less, and especially 7 mol% or more or 22 mol% or less. It is more desirable. By being within this range, a matte feeling can be effectively provided while maintaining film forming stability.

Representative polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), and the like.

(Base layer)

The base layer of the polyester film base is the thickest layer among the layers constituting the polyester film base, and its composition is arbitrary as long as the polyester is the main component resin.

The base material layer may be provided with a layer containing particles, or may be composed of only a layer containing particles. However, from the viewpoint of cost, it is preferable that the layer does not contain particles such as organic particles and inorganic particles described later.

From the viewpoint of preventing curling of the present polyester film 10, the thickness of the base layer is preferably 60 to 99% of the polyester film base thickness, especially 65% or more or 99% or less, and especially 70% or more. It is more preferable that it is 99% or less. By being within this range, elasticity is created in the base material layer itself, making it difficult for the present polyester film 10 to curl.

(Particle-containing layer A)

The particle-containing layer A is a layer containing particles

The particles X contained in the particle-containing layer A preferably have an average particle diameter of 2.0 μm or more.

When the particle-containing layer A contains particles However, if the particles

Therefore, the average particle diameter of the particles

In addition, when the particles are powder, the average particle size of the particles The particle size (d50) of 50% of the integrated volume fraction in the equivalent spherical distribution of the powder measured using the particle size can be taken as the average particle size. The average particle diameter of the particles in the film or layer can be obtained by observing 10 or more particles X with a scanning electron microscope (SEM), measuring the diameter of the particles At that time, in the case of non-spherical particles, the average value of the longest diameter and shortest diameter can be measured as the diameter of each particle X. The same applies to particle Y, which will be described later.

The shape of particle X is arbitrary. For example, it may be spherical, blocky, rod-shaped, flat, etc. However, from the viewpoint of obtaining a uniform mat surface, it is preferable that it is spherical.

There are no particular restrictions on the hardness, specific gravity, color, etc. of the particles X, and two or more different types may be used together.

The particles For example, inorganic particles may be used, organic particles may be used, or crosslinked polymer particles may be used.

Inorganic particles are preferable from the viewpoint that voids may form in the film when stretched, and there is no need to add white pigment to improve visibility, and organic particles are preferred because voids are less likely to form, so the strength of the film does not decrease. From this point of view, it is desirable.

Inorganic particles include, for example, silica, calcium carbonate, kaolin, talc, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, titanium oxide, zirconium oxide, lithium fluoride, Examples include calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide.

In addition, the silica particles may contain, for example, hydrous silicon dioxide in addition to silicon dioxide (SiO ₂ ).

Examples of organic particles include acrylic resin, styrene resin, urea resin, phenol resin, epoxy resin, and benzoguanamine resin.

Among them, particles made of a resin containing methyl methacrylate, styrene, or both as copolymerization components are particularly preferable because they have good compatibility with PET film.

Examples of crosslinked polymer particles include single or copolymers of vinyl monomers of divinylbenzene, styrene, acrylic acid, methacrylic acid, acrylic acid, or methacrylic acid. Other crosslinkable polymer particles such as polytetrafluoroethylene, benzoguanamine resin, thermosetting epoxy resin, unsaturated polyester resin, thermosetting urea resin, and thermosetting phenol resin may be used.

The content of particles And, more preferably, it is 1 mass% or more or 18 mass% or less, especially 2 mass% or more or 15 mass% or less, and especially 3 mass% or more or 10 mass% or less.

Additionally, the particle-containing layer A may contain particles Y, which will be described later.

The thickness of the particle-containing layer A is preferably 1.0 to 20 μm, especially 2.0 μm or more or 20 μm or less, particularly 3.0 μm or more or 20 μm or less, and especially 4.0 μm or more or 15 μm or less. .

By setting the thickness of the particle-containing layer A to 1.0 μm or more, a matte feeling can be effectively provided. In addition, if the thickness of the particle-containing layer A exceeds 20 μm, the effect of improving the matte feeling becomes low, and there is a risk that the roughening of the film surface caused by the particles X may be reduced.

The relationship between the thickness of the particle-containing layer A and the average particle diameter of the particles It is preferable, 0.3 or more and 4.0 or less are more preferable, and 0.5 or more and 3.0 or less are especially preferable.

(Particle-containing layer B)

As described above, the particle-containing layer A can be provided on one side of the base layer, and the particle-containing layer B, which is different from the particle-containing layer A, can be formed on the other side of the base layer. Although it is not necessary to provide the release layer described later on the surface of the particle-containing layer B, the configuration of providing the release layer is not excluded.

Since curling of the entire polyester film 10 can be prevented, it is preferable that the particle-containing layer B also contains particles

However, since the surface of the particle-containing layer B can be roughened to the extent of appropriate handling, it is not necessary to roughen it to the extent of the surface of the particle-containing layer A. Therefore, the content of particles Since the particle-containing layer B has a lower content of particles On the other hand, it is possible to easily laminate a desired layer on the surface of the particle-containing layer B.

Specifically, the content (% by mass) of particles X contained in particle-containing layer B is preferably 0.1 to 100% of the content (% by mass) of particles Alternatively, it is more preferable that it is 95% or less, especially 5% or more or 90% or less, and especially 10% or more or 80% or less, especially 60% or less.

The particle-containing layer B may contain particles Y with an average particle diameter of less than 2.0 μm in order to whiten the present polyester film 10.

At this time, the particle-containing layer B may not contain particles X but may contain particles Y, or may contain particles Y together with particles X.

When containing particle Y together with particle :15 is more preferable.

The shape of particle Y is arbitrary. For example, it may be spherical, blocky, rod-shaped, flat, etc. However, from the viewpoint of making it difficult to generate coarse protrusions due to agglomeration, it is preferable that they are spherical.

There are no particular restrictions on the hardness, specific gravity, color, etc. of the particles Y, and two or more different types may be used together.

The average particle diameter of the particles Y is preferably 0.05 ㎛ to 0.50 ㎛ from the viewpoint of imparting white opacity due to the light scattering effect, especially 0.10 ㎛ or more or 0.45 ㎛ or less, especially 0.20 ㎛ or more or 0.40 ㎛ or less, especially It is more preferable that it is 0.25 ㎛ or more.

The particles Y are preferably metal compound particles from the viewpoint of providing white opacity due to the light scattering effect.

Examples of metal compound particles include titanium oxide, calcium carbonate, barium sulfate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and zirconium oxide, and among them, titanium oxide. , metal compound particles such as calcium carbonate and barium sulfate.

Additionally, in the particle-containing layer B, when the particles corresponding to particle It is nothing but one type of particle with an average particle size. In such a case, it is recognized as either particle X or particle Y based on the average particle diameter after mixing.

The thickness of the particle-containing layer B is preferably in the same range as the thickness of the particle-containing layer A from the viewpoint of preventing curling of the present polyester film 10. From this point of view, the thickness of the particle-containing layer B is also preferably 1.0 to 20 ㎛, especially 2.0 ㎛ or more or 18 ㎛ or less, especially 3.0 ㎛ or more or 17 ㎛ or less, and especially 4.0 ㎛ or more or 15 ㎛ or less. It is more desirable.

From the viewpoint of preventing curling of the present polyester film 10, the ratio of the thicknesses of the particle-containing layer A and the particle-containing layer B is preferably (thickness of particle-containing layer A)/(thickness of particle-containing layer B) being 0.1 or more and 10 or less, Among these, 0.2 or more or 5.0 or less is more preferable, and among these, 0.5 or more or 2.0 or less is particularly preferable.

(Other ingredients)

Conventionally known weatherproofing agents, lightproofing agents, light-shielding agents, antioxidants, heat stabilizers, lubricants, antistatic agents, fluorescent whitening agents, dyes, pigments, etc. can be added to each layer constituting the polyester film base material as needed. . Additionally, depending on the intended use, an ultraviolet absorber, especially a benzoxazinone-based ultraviolet absorber, etc. may be contained.

< Heterogeneous layer >

The present polyester film 10 preferably has a structure in which a release layer is formed on the surface of the particle-containing layer A of the polyester film base material.

The release layer preferably has a crosslinked structure derived from a crosslinking agent. If it has such a cross-linked structure, it can have excellent hardness and therefore can sufficiently withstand when the present polyester film 10 is press-bonded to an object.

The thickness of the release layer is preferably 0.001 to 1 ㎛ from the viewpoint of having release properties but not smoothing (not reducing) the roughness of the surface of the polyester film base material, especially 0.002 ㎛ or more or 0.5 ㎛ or less. Among these, it is more preferable that it is 0.005 ㎛ or more or 0.2 ㎛ or less, especially 0.008 ㎛ or more or 0.15 ㎛ or less, especially 0.01 ㎛ or more or 0.1 ㎛ or less, and especially 0.01 ㎛ or more or 0.08 ㎛ or less.

The thickness of the release layer is preferably 0.1 to 100% of the average surface roughness (Ra) of the surface on which the release layer is provided, especially 0.2% or more or 50% or less, and especially 1.0% or more or 25% or less.

(Formation of release layer)

Since the release layer is preferably provided as a very thin film on the surface of the particle-containing layer A, that is, the roughened surface, it is preferably formed by employing an application and stretching method (in-line coating). However, it is not limited to this method.

As an application stretching method, for example, in sequential biaxial stretching, the surface of the particle-containing layer A is coated with a “release layer forming composition” especially after the first stage stretching is completed and before the second stage stretching. desirable. In this way, application becomes possible simultaneously with stretching, and the thickness of the release layer can be made thin depending on the stretching ratio, making it possible to manufacture a film suitable as a polyester film.

Methods for applying a coating liquid composed of a release layer forming composition include, for example, air doctor coating, blade coating, rod coating, bar coating, knife coating, squeeze coating, impregnation coating, reverse roll coating, transfer roll coating, and gravure coating. Conventionally known application methods such as kiss roll coating, cast coating, spray coating, curtain coating, calendar coating, and extrusion coating can be used.

More specifically, for example, in sequential biaxial stretching, a uniaxially stretched film, especially stretched in the longitudinal direction (machine direction), is coated with a coating liquid consisting of a release layer forming composition, and then stretched in the transverse direction to form a poly film. The method for forming the ester film is excellent. According to this method, there is an advantage in terms of manufacturing cost because the formation of the polyester film and the formation of the release layer can be performed at the same time, and since stretching is performed after coating, the thickness of the release layer can be changed depending on the stretching ratio. And, compared to offline coating, thin film coating can be performed more easily.

Moreover, by providing a release layer on the polyester film before stretching, the release layer can be stretched together with the polyester film, and thereby the release layer can be firmly adhered to the polyester film. Additionally, in the production of a biaxially stretched polyester film, by stretching the film while holding its ends with clips, etc., the film can be restrained in the longitudinal and transverse directions, and wrinkles, etc., do not occur in the heat setting process. It can be exposed to high temperatures while maintaining flatness.

Therefore, since the heat treatment performed after coating can be performed at a high temperature that cannot be achieved by other methods, the film forming property of the release layer is improved, and the release layer and the polyester film are adhered more tightly. It can be done, and furthermore, it can be made into a strong release layer.

In addition, regardless of whether the release layer is formed by offline coating or in-line coating, heat treatment and active energy ray irradiation such as ultraviolet ray irradiation may be used in combination as needed. In order to improve the applicability and adhesion of the coating liquid forming the release layer to the polyester film, the polyester film is subjected to surface treatment such as chemical treatment, corona discharge treatment, plasma treatment, ozone treatment, chemical treatment, or solvent treatment before application. Processing may be performed.

Examples of the release layer forming composition, that is, the coating liquid, include a resin composition containing a release agent and a binder.

There is no particular limitation as a “mold release agent” to be blended in the release layer forming composition, and it is possible to use a conventionally known release agent. Examples include long-chain alkyl group-containing compounds, fluorine compounds, silicone compounds, and waxes.

Among them, long-chain alkyl group-containing compounds and waxes are preferable from the viewpoint that the possibility of contamination is small even when applied to optical applications, and waxes are preferable from the viewpoint that peelability does not significantly decrease even when heated.

Examples of the wax include natural wax, synthetic wax, and modified wax.

Natural waxes include plant waxes, animal waxes, mineral waxes, and petroleum waxes.

Examples of plant-based waxes include candelilla wax, carnauba wax, rice bran wax, wood wax, and jojoba oil.

Examples of animal wax include beeswax, lanolin, whale wax, etc. Examples of mineral waxes include montan wax, ozokerite, and ceresin.

Examples of petroleum wax include paraffin wax, microcrystalline wax, and petrolatum.

Examples of synthetic waxes include synthetic hydrocarbons, modified waxes, hydrogenated waxes, fatty acids, acid amides, amines, imides, esters, ketones, Fischer-Tropsch wax (also known as sazole wax), and polyethylene wax. In addition, the following polymers are relatively low molecular weight polymers (specifically, polymers with a number average molecular weight of 500 to 20,000), namely, polypropylene, ethylene-acrylic acid copolymer, polyethylene glycol, polypropylene glycol, polyethylene glycol, and polypropylene glycol. Block or graft combinations, etc. can be mentioned.

Examples of modified wax include montan wax derivatives, paraffin wax derivatives, and microcrystalline wax derivatives. The derivative here is a compound obtained through any of purification, oxidation, esterification, saponification, or a combination thereof. Hydrogenated waxes include hydrogenated castor oil and hydrogenated castor oil derivatives.

Among them, from the viewpoint of stabilizing characteristics such as blocking, synthetic wax is preferable as a mold release agent in the mold release layer, and among these, polyethylene wax is more preferable, and polyethylene oxide wax is still more preferable.

The number average molecular weight of synthetic wax is usually 500 to 30,000, preferably 1,000 to 15,000, and more preferably 2,000 to 8,000 from the viewpoint of stability of properties such as blocking and handleability.

Moreover, considering heating for crosslinking etc. when forming the release layer, it is preferable among the above waxes that the melting point or softening point is 80°C or higher, especially 110°C or higher. The upper limit of the melting point or softening point of wax is not limited and is usually 300°C or lower.

The proportion of the release agent in the release layer forming composition is preferably 1 to 50% by mass of the non-volatile component, more preferably 5% by mass or more or 40% by mass or less, and more preferably 10% by mass or more or 30% by mass or less. do.

When the ratio of the release agent in the release layer forming composition is within the above range, the coating film strength can be increased while maintaining good release properties.

In order to increase the strength of the release layer and further improve wettability, it is preferable that the composition for forming the release layer contain a crosslinking agent. When the release layer forming composition contains a crosslinking agent, the formed release layer has a crosslinked structure derived from the crosslinking agent.

Moreover, in order to increase the strength of the release layer and further improve the adhesion between the polyester film base material and the release layer, it is preferable that the release layer forming composition contains a binder.

As the crosslinking agent, conventionally known materials can be used. Examples include oxazoline compounds, isocyanate compounds, epoxy compounds, melamine compounds, carbodiimide compounds, silane coupling compounds, hydrazide compounds, and aziridine compounds. Among them, oxazoline compounds, isocyanate-based compounds, epoxy compounds, melamine compounds, carbodiimide-based compounds, and silane coupling compounds are preferable. In order to further strengthen the strength of the release layer, melamine compounds and oxazoline compounds are preferable, and in order to improve adhesion to the film of the substrate, oxazoline compounds, isocyanate compounds, epoxy compounds, and carbodiimide compounds are preferable. , especially oxazoline compounds and isocyanate-based compounds are preferable.

Specific examples of binders include acrylic resin, polyvinyl (polyvinyl alcohol, vinyl chloride vinyl acetate copolymer, etc.), polyester resin, urethane resin, polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starch, etc. can be mentioned. Among these, polyester resin is preferable from the viewpoint of improving the adhesion between the polyester film base material and the mold release layer.

The acrylic resin is a polymer made of polymerizable monomers including acrylic and methacrylic monomers. These may be homopolymers or copolymers, or even copolymers with polymerizable monomers other than acrylic or methacrylic monomers. Additionally, copolymers of these polymers with other polymers (eg, polyester, polyurethane, etc.) are also included. For example, block copolymers and graft copolymers. Alternatively, polymers obtained by polymerizing polymerizable monomers in a polyester solution or polyester dispersion (in some cases, a mixture of polymers) are also included. Likewise, polymers obtained by polymerizing polymerizable monomers in polyurethane solutions and polyurethane dispersions (and in some cases, mixtures of polymers) are also included. Likewise, polymers (polymer mixtures in some cases) obtained by polymerizing polymerizable monomers in other polymer solutions or dispersions are also included. Additionally, in order to further improve adhesion to the substrate, it is also possible to contain a hydroxyl group or an amino group.

The polymerizable monomer is not particularly limited, but particularly representative compounds include, 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 their salt; Various products such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, monobutylhydroxyl fumarate, and monobutylhydroxyitaconate. Hydroxyl group-containing monomers; Various (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and lauryl (meth)acrylate; various nitrogen-containing compounds such as (meth)acrylamide, diacetoneacrylamide, N-methylolacrylamide, or (meth)acrylonitrile; Various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, and vinyl toluene, various vinyl esters such as vinyl propionate; Various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, etc.; Phosphorus-containing vinyl monomers; Various vinyl halides such as vinyl chloride and vinylidene chloride; Various conjugated dienes such as butadiene can be mentioned.

When the acrylic resin contains a hydroxyl group, the hydroxyl value of the acrylic resin is preferably 2 to 100 mgKOH/g, more preferably 5 to 50 mgKOH/g. When the hydroxyl value falls within the above range, the application appearance and transparency are improved.

The above-mentioned polyvinyl alcohol is a compound having a polyvinyl alcohol moiety. For example, conventionally known polyvinyl alcohol can be used, including modified compounds in which polyvinyl alcohol is partially acetalized or butyralized. . The degree of polymerization of polyvinyl alcohol is not particularly limited, but is usually 100 or more, preferably in the range of 300 to 40,000. When the degree of polymerization is less than 100, the water resistance of the release layer may decrease. The degree of saponification of polyvinyl alcohol is not particularly limited, but is usually 70 mol% or more, preferably 70 to 99.9 mol%, more preferably 80 to 97 mol%, particularly preferably 86 to 95 mol%. % polyvinyl acetate saponification is used practically.

As a main component of the polyester resin, for example, those composed of polyhydric carboxylic acid and polyhydric hydroxy compound as shown below. That is, examples of polyhydric carboxylic acids include 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. Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedi Carboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, trimellitic acid monopotassium salt and their ester-forming derivatives can be used. Polyvalent hydroxy compounds include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and 2-methyl-1. , 5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, poly Tetramethylene glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropionate, etc. can be used. Among these compounds, one or more may be appropriately selected and a polyester resin may be synthesized by a polycondensation reaction using a conventional method.

The urethane resin is a polymer compound having a urethane bond in the molecule. Usually, urethane resin is produced by the reaction of polyol and isocyanate. Examples of polyols include polycarbonate polyols, polyester polyols, polyether polyols, polyolefin polyols, and acrylic polyols, and these compounds may be used individually or in plural types.

The polycarbonate polyols are obtained from polyhydric alcohols and carbonate compounds through dealcoholization. Polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexane. Diol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol , 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, etc. Carbonate compounds include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and ethylene carbonate. Examples of polycarbonate-based polyols obtained from these reactions include poly(1,6-hexylene)carbonate and poly( and 3-methyl-1,5-pentylene)carbonate.

Examples of the polyester polyols include polyhydric carboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or their acid anhydrides; Polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1 ,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 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, and those obtained from the reaction of 3-propanediol, cyclohexanediol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyldialkanolamine, lactonediol, etc.).

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

Polyisocyanate compounds used to obtain urethane resin include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylenediphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate, α,α,α' Aliphatic diisocyanates having aromatic rings such as α'-tetramethylxylylene diisocyanate, aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate, and cyclohexane. Alicyclic diisocyanates such as diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and isopropylidene dicyclohexyl diisocyanate are exemplified. These may be used individually, or multiple types may be used together.

When synthesizing a urethane resin, a chain extender may be used. The chain extender is not particularly limited as long as it has two or more active groups that react with an isocyanate group. Generally, it is a chain having two hydroxyl groups or two amino groups. Extension agents are mainly available.

Examples of chain extenders having two hydroxyl groups include aliphatic glycols such as ethylene glycol, propylene glycol, and butanediol, aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene, and neopentyl glycol hydroxypivalate. Glycols such as ester glycol can be mentioned. Moreover, examples of chain extenders having two amino groups include aromatic diamines such as tolylenediamine, xylylenediamine, and diphenylmethanediamine, ethylenediamine, propylenediamine, hexanediamine, and 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, Aliphatic diamines such as 1,10-decanediamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, isopropylidenecyclohexyl-4,4'-diamine, 1 and alicyclic diamines such as ,4-diaminocyclohexane and 1,3-bisaminomethylcyclohexane.

The urethane resin in the present invention may use a solvent as a medium, but preferably uses water as a medium. To disperse or dissolve urethane resin in water, there are a forced emulsification type using an emulsifier, a self-emulsification type that introduces a hydrophilic group into the urethane resin, or a water-soluble type. In particular, a self-emulsifying type obtained by introducing an ionic group into the structure of the urethane resin to ionomerize it is preferable because it is excellent in the storage stability of the liquid and the water resistance and transparency of the resulting release layer.

In addition, various ionic groups to be introduced include carboxyl groups, sulfonic acids, phosphoric acids, phosphonic acids, quaternary ammonium salts, etc., but carboxyl groups are preferred. As a method for introducing a carboxyl group into the urethane resin, various methods can be used in each step of the polymerization reaction.

For example, when synthesizing a prepolymer, there is a method of using a resin having a carboxyl group as a copolymerization component, or a method of using a component having a carboxyl group as a single component such as polyol, polyisocyanate, or chain extender. In particular, a method using a carboxyl group-containing diol to introduce a desired amount of carboxyl groups depending on the amount of this component introduced is preferable. For example, with respect to the diol used in the polymerization of urethane resin, dimethylolpropionic acid, dimethylolbutanoic acid, bis-(2-hydroxyethyl)propionic acid, bis-(2-hydroxyethyl)butanoic acid, etc. can be copolymerized. . Moreover, it is preferable that this carboxyl group is in the form of a salt neutralized with ammonia, amine, alkali metal, inorganic alkali, etc. Particularly preferred are ammonia, trimethylamine and triethylamine. In such a polyurethane resin, the carboxyl group from which the neutralizing agent is removed in the drying process after application can be used as a crosslinking reaction point by another crosslinking agent. This makes it possible to further improve the durability, solvent resistance, water resistance, blocking resistance, etc. of the resulting release layer in that it has excellent stability in the liquid state before application.

The proportion of the binder in the release layer forming composition is preferably 20 to 70% by mass of the non-volatile component, particularly 30% by mass or more or 65% by mass or less, and more particularly 40% by mass or more or 60% by mass or less. desirable.

The proportion of the crosslinking agent is preferably 10 to 70% by mass of the non-volatile component, more preferably 15% by mass or more or 60% by mass or less, and more preferably 20% by mass or more or 40% by mass or less.

In addition, the coating liquid composed of the release layer forming composition may be an aqueous coating liquid using water as a solvent or a coating liquid containing an organic solvent as a main component, but it is preferable that it is an aqueous coating liquid.

The aqueous coating liquid may contain a small amount of organic solvent.

Examples of the organic solvent include alcohols such as ethanol, isopropanol, ethylene glycol, and glycerin; ethers such as ethyl cellosolve, t-butyl cellosolve, propylene glycol monomethyl ether, and tetrahydrofuran; Ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; Amines such as methylethanolamine can be exemplified. These can be used individually or in combination. By appropriately selecting and containing these organic solvents in the aqueous coating liquid as needed, the stability and applicability of the coating liquid can be improved.

If necessary, the release layer forming composition may contain particles to improve blocking or slipperiness. Additionally, it is possible to contain an antifoaming agent, an applicability improver, a thickener, an organic lubricant, an ultraviolet absorber, an antioxidant, a foaming agent, etc. in the functional layer.

<This polyester film 10>

(thickness)

The thickness of this polyester film 10 is not particularly limited as long as it is within a range that can be formed as a film. Among them, from the viewpoint of mechanical strength, handling properties, productivity, etc., it is preferable that it is 1 ㎛ to 300 ㎛, especially 5 ㎛ or more or 125 ㎛ or less, and especially 8 ㎛ or more or 100 ㎛ or less.

(Permeation concentration OD value)

It is preferable that this polyester film 10 has a transmission density OD value of 0.10 or more.

A transmission density OD value of 0.10 or more means that the opacity is high, or in other words, the whiteness is high.

From this point of view, it is more preferable that the transmission density OD value of the present polyester film 10 is 0.10 to 1.0, especially 0.15 or more or 0.90 or less, especially 0.20 or more or 0.80 or less, especially 0.25 or more, especially 0.30 or more, Among these, it is more preferable that it is 0.50 or more.

If the transmission density OD value of the present polyester film 10 is within the above range, visibility, in other words, discriminability, is good, and therefore it becomes easy to peel off the present polyester film 10 after transferring the rough surface to the transfer object.

As a method of increasing the transmission density OD value of the polyester film 10 to 0.10 or more, for example, a white pigment is contained in the polyester film base or any layer, or the difference in refractive index between the polyester film base and the main component resin is used. Known methods can be employed, such as incorporating large materials into the substrate or particle-containing layer, or stretching a film containing fine particles to form voids in the polyester film substrate.

Among them, when whitening is achieved by containing a white pigment, for example, metal compound particles, for example, any of the base layer, the particle-containing layer, and the layer provided on the opposite side to the particle-containing layer of the base layer. Whitening can be achieved by containing metal compound particles in one layer or two or more of them. At this time, examples of the white pigment include the above-mentioned particles Y having an average particle diameter of less than 2.0 μm.

(Surface roughness of the film)

The average surface roughness (Ra) of this polyester film 10 is preferably 0.05 ㎛ to 2.0 ㎛.

Here, the average surface roughness (Ra) of the present polyester film 10 means the surface when a release layer is formed on one side of the polyester film base material, and the release layer is formed on both sides of the polyester film base material. When formed, it means both surfaces.

If the average surface roughness (Ra) of the surface of the present polyester film 10 is in the above range, a matte feeling can be expressed, and the matte feeling can be imparted to the surface of the object by pressing and releasing this surface to the object.

From this point of view, the average surface roughness (Ra) of the polyester film 10 is preferably 0.05 ㎛ to 2.0 ㎛, more preferably 0.1 ㎛ or more or 1.0 ㎛ or less, and more preferably 0.2 ㎛ or more or 0.9 ㎛ or less. .

The average surface roughness (Ra) of this polyester film 10 can be determined using a surface roughness measuring instrument, for example, using a surface roughness measuring instrument (SE-3500) manufactured by Kosaka Laboratories Co., Ltd.

In order to set the average surface roughness (Ra) of the present polyester film 10 to 0.1 μm to 2.0 μm, for example, a particle-containing layer A is provided and the average surface roughness of one or both surfaces of the polyester film base material ( Ra) may be set to 0.1 μm to 2.0 μm, and the thickness of the release layer may be sufficiently thin relative to the average surface roughness (Ra). However, it is not limited to this method.

In addition, if one surface of this polyester film 10 is made into a matte surface, it is enough for the other surface to be roughened to the extent that there is no problem in handling, and it is not necessary to be a matte surface.

Therefore, the average surface roughness (Ra) 1 of the surface of the particle-containing layer A side of the polyester film base, that is, the release layer side, is set to 0.1 μm to 2.0 μm, and the average surface roughness (Ra) of the surface of the polyester film 10 on the opposite side is set to ) 2 may be less than 0.1 ㎛. At this time, the ratio of (Ra) 2 to (Ra) 1 is preferably 0.01 to 100%, especially 0.1% or more, especially 1% or more, especially 3% or more or 90% or less. do.

(Glossiness)

In this polyester film 10, it is preferable that the glossiness of at least the surface on the release layer side is 30% or less.

If the glossiness of the film surface is 30% or less, it can be made into a high-quality matte tone. However, the lower limit is about 0.1%.

From this point of view, in the present polyester film 10, it is preferable that the glossiness of at least the surface on the release layer side is 30% or less, especially 0.1% or more or 30% or less, especially 25% or less, and especially 20% or less. desirable.

In addition, the glossiness of the surface on the release layer side of this polyester film 10 can be measured using a glossmeter, for example, using a glossmeter type VG2000 manufactured by Nippon Denshoku Co., Ltd., according to the method of JIS Z8741. degrees can be measured.

In the present polyester film 10, in order to make the glossiness of at least the surface on the release layer side 30% or less, as described above, the average surface roughness (Ra) of one or both surfaces of the polyester film base material is 0.05 ㎛ to 2.0. It can be formed in this way by setting it to ㎛ and making the thickness of the release layer sufficiently thin with respect to the average surface roughness (Ra). However, it is not limited to this method.

(Peeling force of release layer)

In this polyester film 10, the peeling force of the release layer is preferably 100 to 3500 mN/cm, especially 500 mN/cm or more or 3000 mN/cm or less, and especially 1000 mN/cm or more or 2500 mN/cm. It is more preferable to be less than ㎝. By setting it within this range, the peeling operation becomes easy. In addition, the value of the peeling force corresponds to the “peeling force of the release layer before heating” described later.

The peeling force of the release layer before heating was measured by pressing an adhesive tape (polyester adhesive tape "No. 31B" manufactured by Nitto Denko Co., Ltd.) on the surface of the release layer once with a 2 kg rubber roller and leaving it for 1 hour at room temperature. It can be measured by performing 180° peeling under the conditions of a tensile speed of 300 mm/min using “AGX-plus” manufactured by the manufacturer.

In addition, the peeling force of the release layer after heating is preferably 100 to 4500 mN/cm, especially 500 mN/cm or more or 3900 mN/cm or less, and especially 1000 mN/cm or more or 3500 mN/cm or less. It is more desirable. By setting this range, peeling can be sufficiently performed even after heating.

In addition, the peeling force of the release layer after heating was obtained by pressing an adhesive tape (polyester adhesive tape "No. 31B" manufactured by Nitto Denko Co., Ltd.) on the surface of the release layer for one round using a 2 kg rubber roller in an oven at 100°C. It can be measured by heating for 1 hour and then leaving it at room temperature for 1 hour. The peeling force can be measured by performing 180° peeling using “AGX-plus” manufactured by Shimadzu Corporation under the condition of a tensile speed of 300 mm/min.

In addition, considering the ease of controlling the peel force of the release layer before and after heating, the peel force before and after heating is compared, and the value of the difference in peel force before and after heating = (peel force after heating - peel force before heating) is preferable. Typically, it is 0 to 3000 mN/cm, more preferably 0 to 2000 mN/cm, and even more preferably 0 to 1500 mN/cm.

<Method for producing polyester film 1 or 10>

Below, an example of the manufacturing method of the present polyester film 10 will be described. However, the manufacturing method of this polyester film 10 is not limited to the method described below.

First, by a known method, each raw material is prepared for each dried or undried layer, that is, the base material layer, particle-containing layer A, particle-containing layer B, and additional other layers, and each is supplied to each melt extrusion device. and melted by heating to a temperature above the melting point of each polymer. Next, the molten polymer of each layer is usually guided to a die via a multi-manifold or feed block and laminated.

Next, the molten sheet extruded from the die is rapidly cooled and solidified on a rotating cooling drum to a temperature below the glass transition temperature, and an unoriented sheet in a substantially amorphous state is obtained. In this case, in order to improve the flatness of the sheet, it is desirable to increase the adhesion between the sheet and the rotary cooling drum, and the electrostatic application adhesion method and/or the liquid application adhesion method are preferably employed.

Next, the obtained unstretched sheet is stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 150°C, preferably 80 to 140°C, and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, it is stretched in a direction perpendicular to the stretching direction of the first stage, usually at 70 to 170°C, and at a draw ratio of usually 2.5 to 7 times, preferably 3.0 to 6 times. Subsequently, heat treatment is performed at a temperature of 180 to 270°C under tension or relaxation within 30% to obtain a biaxially oriented film. In the above stretching, a method of performing stretching in one direction in two or more steps may be adopted. In that case, it is preferable to perform the stretching so that the final draw ratios in the two directions fall within the above ranges.

After the heat treatment process, it is preferable to relax 2 to 20% in the longitudinal and/or transverse directions in the highest temperature zone of the heat treatment and/or in the cooling zone at the heat treatment outlet. Additionally, it is also possible to add material longitudinal stretching and material transverse stretching as needed.

In the above manufacturing method, the release layer is preferably coated with the “release layer forming composition” during the longitudinal stretching and the lateral stretching using the above-described coating stretching method. In this way, application becomes possible simultaneously with stretching, and the thickness of the release layer can be made thin depending on the stretching ratio, making it possible to manufacture a film suitable as a polyester film.

Regarding polyester film 1, the film thickness in polyester film 10 described above is read as the film thickness in polyester film 1, and the transmission density OD value in polyester film 10 described above is as described above. It is read as the transmission density OD value in the polyester film 1, and the average surface roughness (Ra) in the polyester film 10 described above is read as the average surface roughness (Ra) in the polyester film 1.

Since this polyester film 1 and this polyester film 10 have a roughened film surface and can transfer the surface state to the surface of the target product, they can be used for surface shaping applications that require a matte surface. In particular, it can be suitably used as a film for forming the surface of an electromagnetic wave shield member.

< Explanation of phrases >

In this specification, when expressed as “X to Y” (X and Y are arbitrary numbers), unless otherwise specified, it means “not less than It also includes the meaning of “smaller than Y.”

Additionally, when it is expressed as “more than Also includes.

[Example]

Below, the present invention is further detailed based on the following examples and comparative examples.

First, the measurement and evaluation methods of various physical properties in the following examples and comparative examples will be described.

In addition, in Examples and Comparative Examples, “part” refers to “mass part.” Additionally, the measurement method used in the present invention is as follows.

(1) Intrinsic viscosity of polyester

1 g of polyester from which incompatible particles were removed was precisely weighed, 100 ml of a mixed solvent of phenol/tetrachloroethane = 50/50 (mass ratio) was added and dissolved, and the mixture was dissolved at 30°C. It was measured in .

(2) Average particle diameter of particles

The particle size was measured by the sedimentation method using a centrifugal sedimentation particle size distribution measuring device, SA-CP3 type, manufactured by Shimadzu Corporation. The value of 50% of the integration (volume basis) of the equivalent spherical distribution of particles obtained by measurement was used to refer to the average particle size.

(3) Method of measuring average surface roughness (Ra)

The surface roughness was determined as follows using a surface roughness measuring instrument (SE-3500) manufactured by Kosaka Laboratories Co., Ltd. That is, a portion of reference length L (2.5 mm) is extracted from the film cross-section curve in the direction of the average line, the average line of this extracted portion is set as x-axis, and the direction of longitudinal magnification is set as y-axis, and the roughness curve y=f When expressed as (x), the value given in the following equation is expressed as [nm]. The arithmetic mean roughness was expressed as the average value of the arithmetic mean roughness of the extracted portion obtained from 10 roughness curves from the surface of the sample film and obtained from these roughness curves. Additionally, the tip radius of the stylus was set to 2 μm, the load was set to 30 mg, and the cutoff value was set to 0.08 mm.

Ra＝(1/L)∫L0｜f(x)｜dx

(4) Evaluation of glossiness of polyester film

Glossiness was measured according to the method of JIS Z8741 using a gloss meter type VG2000 manufactured by Nippon Denshoku Co., Ltd. The reflectance of the sample was calculated based on the reflectance of the black standard plate at an incident angle and reflection angle of 60 degrees and was called glossiness.

(5) Film thickness of release layer

The surface of the release layer was dyed with RuO ₄ and embedded in epoxy resin. Thereafter, the section prepared by the ultra-thin sectioning method was stained with RuO ₄ , and the cross section of the release layer was measured using a transmission electron microscope (H-7650 manufactured by Hitachi High Technologies Co., Ltd., acceleration voltage 100 kV).

(6) Transmission concentration OD value

In accordance with JIS K5600-4, the transmission density by white light was measured using a Macbeth densitometer TD-904 type. Measurements were made on 5 points, and the average value was referred to as the OD value. The larger this value, the lower the light transmittance.

(7) Peel force before heating

An adhesive tape (polyester adhesive tape "No. 31B" manufactured by Nitto Denko Co., Ltd.) was pressed back and forth on the surface of the release layer with a 2 kg rubber roller, and the peeling force was measured after leaving it at room temperature for 1 hour. The peeling force was measured by performing 180° peeling under the conditions of a tensile speed of 300 mm/min using “AGX-plus” manufactured by Shimadzu Corporation.

(8) Peeling force after heating

An adhesive tape (polyester adhesive tape "No. 31B" manufactured by Nitto Denko Co., Ltd.) was pressed back and forth on the surface of the release layer with a 2 kg rubber roller, and then heated in an oven at 100°C for 1 hour. Thereafter, the peeling force was measured after being left at room temperature for 1 hour. For the peeling force, 180° peeling was performed using “AGX-plus” manufactured by Shimadzu Corporation under the condition of a tensile speed of 300 mm/min.

(9) Evaluation of heat resistance of release layer

Using the peel force measured in (7) and (8) above, the difference in heat peel force was calculated as difference in heat peel force = (peel force after heating - peel force before heating).

(10) Evaluation of the strength of the release layer

After 10 rounds of the surface of the release layer using a rubbing tester made by Daiheirika Kogyo and a dedicated felt, the felt was observed. If no white powder was visible, it was rated as ○ (very good), if a little white powder was visible, it was rated as ○△ (good), and if some white powder was visible, it was rated as ○△ (good). The one shown was called △(usual), and the one shown on the entire surface was called ×(poor).

(11) Evaluation of curling properties

A polyester film (sample) stored in a room temperature environment for 24 hours in the form of a film roll was cut into 150 mm x 150 mm to obtain a measurement sample piece. The measurement sample piece was placed on a glass plate, the lifting of the four corners from the glass plate was measured, and the curling property was evaluated based on the following criteria.

◎(very good): The average value of the four corners' lifting is more than 0 mm and less than 6 mm.

○ (good): The average value of the lifting of the four corners is more than 6 mm and less than 10 mm.

△(usual): The average value of the lift of the four corners is more than 10 mm and less than 30 mm.

×(poor): The average value of the lifting of the four corners is 30 mm or more

The polyester used in the examples and comparative examples was prepared as follows.

< Polyester (A) >

Polyethylene terephthalate homopolymer (intrinsic viscosity 0.65 dl/g)

< Polyester (B) >

Polyethylene terephthalate homopolymer containing 10% by mass of crosslinked organic particles of alkyl methacrylate-styrene copolymer with an average particle diameter of 4.5 ㎛

< Polyester (C) >

Copolymerized polyethylene terephthalate copolymerized with 22 mol% isophthalic acid as a dicarboxylic acid component.

< Polyester (D) >

Polyethylene terephthalate homopolymer containing 15% by mass of silica particles with an average particle diameter of 4.0 ㎛

< Polyester (E) >

Polyethylene terephthalate homopolymer containing 15% by mass of silica particles with an average particle diameter of 1.5 ㎛

< Polyester (F) >

Polyethylene terephthalate homopolymer containing 50% by mass of titanium oxide particles with an average particle diameter of 0.3 ㎛

The compounds used to form the release layer are as follows.

<Wax Emulsion (IA)>

In an emulsification equipment with an net capacity of 1.5 L equipped with a stirrer, thermometer, and temperature controller, 300 g of polyethylene oxide wax with a melting point of 140°C, 650 g of ion-exchanged water, 50 g of decaglycerin monooleate surfactant, and 10 g of 48% potassium hydroxide aqueous solution. was added and substituted with nitrogen, sealed, stirred at high speed at 150°C for 1 hour, cooled to 130°C, passed through a high-pressure homogenizer under 400 atm, cooled to 40°C, and obtained wax emulsion (IA).

<Wax Emulsion (IB)>

Wax emulsion (IB) was obtained using the same method as the method for producing wax emulsion (IA), except that paraffin wax with a melting point of 60°C was used.

<Long chain alkyl compound (IC)>

200 parts of xylene and 600 parts of octadecyl isocyanate were added to a four-necked flask and heated with stirring. From the time the xylene began to reflux, 100 parts of polyvinyl alcohol with an average degree of polymerization of 500 and a degree of saponification of 88 mol% were added in small portions at 10-minute intervals over a period of about 2 hours. After all of the polyvinyl alcohol was added, reflux was performed for an additional 2 hours, and the reaction was completed. The reaction mixture was cooled to about 80°C and added into methanol. The reaction product precipitated as a white precipitate. This precipitate was filtered, 140 parts of xylene was added, heated to completely dissolve, and then methanol was added again. After repeating the precipitation operation several times, the precipitate was washed with methanol, dried, and pulverized to obtain a long-chain alkyl compound (IC).

< Fluorine compound (ID) >

In a glass reaction vessel, 80.0 g of CF ₃ (CF ₂ ) nCH ₂ CH ₂ OCOCH = CH ₂ (n = 5 to 11, average of n = 9), which is an acrylate containing a perfluoroalkyl group, is acetoacetoxyethyl methacrylate. 20.0 g, 0.8 g of dodecyl mercaptan, 354.7 g of deoxygenated pure water, 40.0 g of acetone, 1.0 g of C ₁₆ H ₃₃ N(CH ₃ ) ₃ Cl and C ₈ H ₁₇ C ₆ H ₄ O(CH ₂ CH ₂ O ) Add 3.0 g of _n H (n = 8), add 0.5 g of azobisisobutylamidine dihydrochloride, and copolymerize at 60°C for 10 hours while stirring in a nitrogen atmosphere to obtain a copolymer emulsion (ID) of a fluorine compound. got it

<Melamine compound (IIA)>

Hexamethoxymethylolmelamine

<Isocyanate-based compound (IIB)>

1000 parts of hexamethylene diisocyanate was stirred at 60°C, and 0.1 part of tetramethylammonium capriate was added as a catalyst. After 4 hours, 0.2 parts of phosphoric acid was added to stop the reaction, and an isocyanurate-type polyisocyanate composition was obtained. 100 parts of the obtained isocyanurate-type polyisocyanate composition, 42.3 parts of methoxypolyethylene glycol with a number average molecular weight of 400, and 29.5 parts of propylene glycol monomethyl ether acetate were introduced, and kept at 80°C for 7 hours. Thereafter, the temperature of the reaction solution was maintained at 60°C, 35.8 parts of methyl isobutanoylacetate, 32.2 parts of diethyl malonate, and 0.88 parts of a 28% methanol solution of sodium methoxide were added, and maintained for 4 hours. 58.9 parts of n-butanol were added, the reaction mixture was kept at a temperature of 80°C for 2 hours, and then 0.86 parts of 2-ethylhexyl acid phosphate was added to obtain an isocyanate-based compound (IIB) as a blocked polyisocyanate.

< Polyester resin (III) >

(Acid component) Terephthalic acid/Isophthalic acid/5-sodium sulfoisophthalic acid//(Diol component) Ethylene glycol/1,4-butanediol/Diethylene glycol = 56/40/4//70/20/10 (mol%) ) Aqueous dispersion of polyester resin copolymerized at a ratio of

[Example 1]

A raw material mixed with polyester (B) and (C) at a mass ratio of 80% and 20%, respectively, is used as the raw material for the A layer (particle-containing layer A), polyester (A) is used as the raw material for the base layer, and polyester (A) is used as the raw material for the base layer. Raw materials mixed with esters (A), (E), and (F) at mass ratios of 70%, 15%, and 15%, respectively, are used as raw materials for layer B (particle-containing layer B), and each is supplied to three extruders. , each melted at 285°C, then co-extruded in a layer configuration of 3 types of 3 layers (discharge amount of A layer/base layer/B layer = 5:40:5) on cooling rolls set at 35°C, and cooled. It was solidified to obtain an unstretched sheet. Next, after stretching 3.0 times in the longitudinal direction at a film temperature of 85°C using a difference in roll peripheral speed, coating solution 1 shown in Table 1 below was applied to the surface of layer A of this longitudinally stretched film, and applied with a tenter. and stretched 4.1 times at 95°C in the transverse direction, heat treated at 235°C, and then relaxed by 2% in the transverse direction, with a thickness of 50 ㎛ (A layer/base layer/B layer=5 ㎛/40 ㎛/ A polyester film (sample) having a release layer with a dry film thickness of 0.03 μm on the A-layer side of the polyester film base material (5 μm) and having an average surface roughness (Ra) of the surface on the release layer side of 0.6 μm was obtained.

The properties of this polyester film (sample) are shown in Table 2 below.

[Examples 2 to 12]

Except that the composition of the coating liquid was changed to the composition shown in Table 1, it was manufactured in the same manner as in Example 1 to obtain a polyester film (sample). The properties of the obtained polyester film (sample) are shown in Table 2.

The polyester films (samples) of both examples had good average surface roughness (Ra) and gloss, and the difference in peel force before and after heating and the strength of the release layer were also good.

[Example 13]

A raw material mixed with polyester (A), (B), (C), and (F) at a mass ratio of 65%, 10%, 10%, and 15%, respectively, is used as the raw material for layer B (particle-containing layer B), Manufactured in the same manner as in Example 1, except that coating solution 5 shown in Table 1 was applied instead of coating solution 1, and a poly polyester with a thickness of 50 ㎛ (A layer / base layer / B layer = 5 ㎛ / 40 ㎛ / 5 ㎛) A polyester film (sample) having a release layer with a dry film thickness of 0.03 μm on the A layer side of the ester film base material and an average surface roughness (Ra) of the surface on the release layer side of 0.6 μm was obtained.

The properties of this polyester film (sample) are shown in Table 3 below.

[Example 14]

A raw material mixed with polyester (A) and (D) at a mass ratio of 65% and 35%, respectively, is used as the raw material for layer A (particle-containing layer A), polyester (A) is used as a raw material for the base layer, and polyester (A) is used as a raw material for the base layer. A mixed raw material of esters (A) and (E) mixed at a ratio of 85% and 15%, respectively, was used as the raw material for layer B (particle-containing layer B), and each was supplied to three extruders and melted at 285°C. Then, on a cooling roll set at 40°C, it was coextruded in a layer configuration of 3 types of 3 layers (A layer/base layer/B layer = discharge amount of 5:40:5), and cooled and solidified to obtain an unstretched sheet. Except this, it was manufactured in the same manner as in Example 1, and a film thickness after drying of 0.03 ㎛ was placed on the A layer side of a polyester film base material with a thickness of 50 ㎛ (A layer / base layer / B layer = 5 ㎛ / 40 ㎛ / 5 ㎛). A polyester film (sample) was obtained which had a release layer and an average surface roughness (Ra) of 0.4 μm on the surface on the release layer side.

The properties of this polyester film (sample) are shown in Table 2 below.

[Examples 15 to 25]

Except that the composition of the coating liquid was changed to the composition shown in Table 1, it was manufactured in the same manner as in Example 14 to obtain a polyester film (sample). The properties of the obtained polyester film (sample) are shown in Table 2.

The polyester films (samples) of both examples had good average surface roughness (Ra) and gloss, and the difference in peel force before and after heating and the strength of the release layer were also good.

[Comparative Example 3]

The raw materials mixed with polyester (A) and (E) at mass ratios of 65% and 35%, respectively, are used as the raw materials for the A layer (particle-containing layer A), and polyester (A) is used as the raw material for the base layer, and applied. Polyester with a thickness of 50 ㎛ (A layer / base layer / B layer = 5 ㎛ / 40 ㎛ / 5 ㎛) was prepared in the same manner as in Example 14, except that coating solution 5 shown in Table 1 below was applied instead of solution 1. A polyester film (sample) was obtained, which had a release layer with a dry film thickness of 0.03 μm on the A-layer side of the film substrate and an average surface roughness (Ra) of 0.2 μm on the surface of the release layer side.

As the characteristics of this polyester film (sample) are shown in Tables 2 and 3 below, it was a film with high gloss and poor visibility.

[Comparative Example 4]

A raw material mixed with polyester (A) and (B) at a mass ratio of 20% and 80%, respectively, is used as the raw material for layer A (particle-containing layer A), and polyester (A), (B) and (F) are used as raw materials, respectively. Raw materials mixed at mass ratios of 90%, 8%, and 2% were used as raw materials for layer B (particle-containing layer B), supplied to two extruders, melted at 285°C, and then set to 40°C. It was manufactured in the same manner as in Example 1 except that it was co-extruded on a cooling roll with a layer composition of 2 types of 2 layers (discharge amount of A layer/B layer = 5:45) and cooled and solidified to obtain an unstretched sheet, and had a thickness of 50. On the A-layer side of the polyester film base material of ㎛ (A layer / B layer = 5 ㎛ / 45 ㎛), there is a release layer with a dry film thickness of 0.03 ㎛, and the average surface roughness (Ra) of the surface on the release layer side is 0.5 ㎛. A polyester film (sample) was obtained.

As the characteristics of this polyester film (sample) are shown in Table 3 below, it was a film with poor curling properties.

Table 2 demonstrates the first and second polyester films of the present invention, and Table 3 demonstrates the third polyester film of the present invention.

From the results of the above-mentioned examples and the test results conducted so far by the present inventor, it was found that if the transmission density OD value of the polyester film is 0.10 or more, the polyester film can be said to have excellent visibility during transfer.

In addition, by forming a particle-containing layer containing particles with an average particle size of 2.0 ㎛ or more on one side or both sides of the base layer, and further forming a release layer on the surface of the particle-containing layer, the polyester film surface is appropriately roughened. It was possible to do this, and it was found that the expected matte feeling could be transferred to the object.

[Industrial applicability]

Since the present polyester film 10 has excellent visibility during transfer, or in other words, discrimination, and has a roughened film surface, even if a release layer is formed, the roughened state is not smoothed and the expected matte feeling is not achieved on the object. Since it can be provided, it can be suitably used for purposes of transferring a matte surface to an object, especially as a polyester film for surface shaping of an electromagnetic wave shield member.

1: Polyester film
11: Polyester film base
111: base layer
112: Particle-containing layer A
113: Release layer

Claims (15)

It has a particle-containing layer containing particles with an average particle diameter of 2.0 ㎛ or more, and has a transmission concentration OD value of 0.10 or more,
A release layer is provided on the surface of at least one of the particle-containing layers, and a release agent that is a long-chain alkyl group-containing compound, a fluorine compound, a silicone compound, or a wax is blended into the release layer-forming composition forming the release layer,
A polyester film for surface shaping of an electromagnetic wave shield member, wherein the surface on the release layer side has an average surface roughness (Ra) of 0.1 μm to 2.0 μm. A polyester film substrate having a particle-containing layer A containing particles with an average particle diameter of 2.0 μm or more on one side of the base layer, and a particle-containing layer B containing particles with an average particle size of 2.0 μm or more on the other side of the base layer. The content of particles with an average particle diameter of 2.0 ㎛ or more is less in particle-containing layer B than in particle-containing layer A,
A release layer is provided on the surface of the particle-containing layer A, and a release agent that is a long-chain alkyl group-containing compound, a fluorine compound, a silicone compound, or wax is blended in the release layer forming composition forming the release layer,
A polyester film for surface shaping of an electromagnetic wave shield member, wherein the surface on the release layer side has an average surface roughness (Ra) of 0.1 μm to 2.0 μm. According to claim 2,
The polyester film is characterized in that the transmission density OD value is 0.10 or more. delete delete delete The method of claim 1 or 2,
A polyester film characterized in that the glossiness of the surface on the release layer side is 30% or less. delete The method of claim 1 or 2,
A polyester film characterized in that the particles having an average particle diameter of 2.0 μm or more are organic particles. The method of claim 1 or 2,
A polyester film characterized in that the particles having an average particle diameter of 2.0 μm or more are silica particles. According to claim 1,
A polyester film, characterized in that the particle-containing layer contains metal compound particles. According to claim 2 or 3,
A polyester film characterized in that any of the base layer, the particle-containing layer A, and the particle-containing layer B, or two or more layers thereof, contain metal compound particles. delete The method of claim 1 or 2,
A polyester film characterized in that the release layer has a cross-linked structure derived from a cross-linking agent. delete