JP7334416B2 - release film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a release film having a release layer formed by curing an ultraviolet curable silicone release agent on at least one side of a polyester film.

Polyethylene terephthalate (PET) film, which is a typical polyester film, especially biaxially oriented PET film, is excellent in transparency, mechanical strength, heat resistance, flexibility, etc. It is used in various fields such as packaging materials.
A release film having a release layer formed by curing an ultraviolet curable silicone release agent containing a silicone resin as a main component on a polyester film as a base material is used in many fields.

For example, in Patent Document 1, a substrate made of a biaxially stretched polyester film is laminated in order with a first undercoat layer, a second undercoat layer, and a release layer containing a curable silicone resin. A release film is disclosed.

Further, Patent Document 2 discloses a release film having a silicone release layer on at least one side of a polyester film, and a composition forming the release layer containing an ultraviolet curable silicone resin and an onium salt. there is

In recent years, release films have been used as surface protection films for members. As a structure of this type of surface protection film, a structure in which an adhesive layer is provided on the back side of the base film via a release layer, and a hard coat layer is provided on the front side of the base film is common. there were.
For example, in Patent Document 3, a mold release with a coating amount after drying of 0.02 to 0.3 g / m ² is provided in a film production line for a polyester film with a thickness of 8 to 26 μm as a base material. A release film for an optical member surface protection film is disclosed, which is a release film having a layer and has a 180 degree peel strength between the release layer and the adhesive layer of 1 to 6 gf/25 mm.

Further, Patent Document 4 relates to a pressure-sensitive adhesive sheet laminate comprising a pressure-sensitive adhesive sheet and a coating film laminated releasably on one side of the pressure-sensitive adhesive sheet. As a coating film that can be formed on the surface of the pressure-sensitive adhesive sheet with high accuracy, it is a coating film in which a coating layer is provided on at least one side of a copolymer polyester film, and has a storage elastic modulus E′ at 100° C. of 1.5×10 ^{9 .} A coated film is disclosed which has a viscosity of Pa or less and a shrinkage rate of 3.0% or less after being heated at 120° C. for 5 minutes.

JP 2015-202657 A JP 2018-16077 A JP-A-2004-346093 JP 2018-144381 A

In recent years, flexible displays that can be bent at will have been developed, and the range of applications for protective films has expanded. Therefore, in order to apply the release film to a wider range of uses, it is necessary to develop a release film that is not only flexible but also more flexible.

By the way, as disclosed in Patent Document 2, when forming a release layer from an ultraviolet curable silicone resin, the release layer is formed at a low temperature of 100° C. or less in order to cure the release layer by irradiating with ultraviolet rays. It will be. However, when the release layer is formed at such a low temperature, the properties of the release layer tend to change due to the subsequent processing, so there is a problem that the release force is not stable.

Therefore, the problem of the present invention is not only flexible, but also a more flexible release film, and even when the release layer is formed under conditions that are not high temperatures, for example, heating conditions of 100 ° C. or less. , to provide a new release film having stable release force.

The present invention provides a copolymer polyester layer (layer I ) on at least one side of a copolyester film provided with a release layer formed by curing a cationic polymerizable UV-curable silicone release agent composition.

The release film proposed by the present invention is not only flexible, but also a more flexible release film. Therefore, the release film proposed by the present invention is, for example, a component for batteries, adhesive layer protection (protection for OCA (Optical Clear Adhesive), protection for adhesive tape, etc.), transdermal absorption type medicinal separator in the medical field It is also suitable as a protective film for protecting process sheets and image display members used in the manufacturing process, especially for flexible displays and wearable terminals that require flexibility.
Furthermore, the release film proposed by the present invention does not change the properties of the release layer due to, for example, subsequent processing, and can exhibit a stable release force. Therefore, for example, in subsequent processing steps, a protective film that protects the surface of a member that should not be subjected to heat of 100 ° C. or higher, a mold release film that is attached to a surface that requires followability to curved surfaces and unevenness, and even It is particularly suitable for applications such as casting paper, which requires that the release force be as stable as possible.

FIG. 2 is a diagram schematically showing a method of measuring deflection performed in Examples.

Next, an example of an embodiment of the invention will be described. However, the present invention is not limited to the embodiments described below.

<<<Release film>>>
A release film according to an example of the embodiment of the present invention (referred to as "this release film") is a copolymer polyester film comprising a copolymer polyester layer (layer I) containing copolymer polyester A as a main component resin. (referred to as "present copolymer polyester film") provided with a release layer ("present release layer") on at least one side.

Since the release film may have a release layer on at least one side of the copolymer polyester film, the release layer may be provided on both sides of the copolymer polyester film. Another layer may be provided between the polyester film and the release layer.

<<This copolymer polyester film>>
The present copolymerized polyester film, which serves as a base material for the present release film, is, as described above, a single layer or a laminate comprising a copolymerized polyester layer (I layer) containing the copolymerized polyester A as the main component resin. is a film of

The copolymer polyester film may be a non-stretched film (sheet) or a stretched film. Among them, stretched films uniaxially or biaxially stretched are preferred. Among them, a biaxially stretched film is preferable from the viewpoint of excellent balance of mechanical properties and flatness.

<Copolyester layer (I layer)>
The copolyester layer (I layer) is a layer containing copolyester A as a main component resin.

Here, the above-mentioned "main component resin" means the resin having the highest content ratio among the resins constituting the copolyester layer (I layer). The main component resin may account for 30% by mass or more, particularly 50% by mass or more, and 80% by mass or more (including 100% by mass) of the resins constituting the copolyester layer (I layer).

The copolyester layer (layer I) may consist of the copolyester A only, or may contain a resin B other than the copolyester A.
At this time, the resin B is preferably a resin compatible with the copolymer polyester A.
The case where the copolyester layer (layer I) contains the copolyester A and the resin B compatible therewith will be described later.

(Copolyester A)
Copolyester A must be a copolyester which is a copolymer of terephthalic acid and other dicarboxylic acid components and ethylene glycol and other alcohol components.
Copolyester A may be crystalline or amorphous.

Examples of the "other dicarboxylic acid components" include aromatic dicarboxylic acids, alicyclic dicarboxylic acids, aliphatic dicarboxylic acids, and polyfunctional acids. Two or more kinds of "other dicarboxylic acid components" may be used in combination. By using two or more of them in combination, not only can the present copolymerized polyester film be more effectively softened, but also the crystal structure can be maintained, and heat resistance can be obtained in some cases.
Among them, from the viewpoint of facilitating the softening of the present copolymer polyester film, "other dicarboxylic acid components" include aromatic dicarboxylic acids such as isophthalic acid, 2,6-naphthalene dicarboxylic acid and diphenyldicarboxylic acid, adipic acid, and sebacine. acids, aliphatic dicarboxylic acids such as dodecanedioic acid, eicoic acid and their derivatives, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, cyclooctanedicarboxylic acid, or Dimer acid is preferred.
Among the aliphatic dicarboxylic acids, aliphatic dicarboxylic acids having 20 to 80 carbon atoms, preferably 30 or more or 60 or less, especially 36 or more or 48 or less, are particularly preferable from the viewpoint of further lowering the glass transition temperature.

As the dimer acid, a dicarboxylic acid composed of a dimer of an unsaturated fatty acid and having 18 or more carbon atoms in the unsaturated fatty acid is preferable. Examples of such dimer acids include those dimerized with different or identical unsaturated fatty acids selected from oleic acid, elaidic acid, cetoleic acid, erucic acid, brassic acid, linoleic acid, linolenic acid, etc. can be mentioned. Furthermore, hydrogenated products after such dimerization can also be used. The dimer acid may contain an aromatic ring, an alicyclic monocyclic ring, or an alicyclic polycyclic ring.
Among such dimer acids, dimer acids having 20 to 80 carbon atoms, preferably 26 or more or 60 or less, especially 30 or more or 50 or less, are preferable from the viewpoint of further lowering the glass transition temperature.

As described above, "another dicarboxylic acid component" can be arbitrarily selected. Among them, it is preferable to select one or more from aromatic dicarboxylic acids and select one or more from aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and dimer acids and use them together. When an aromatic dicarboxylic acid is used as "another dicarboxylic acid component", there is a tendency that the film can be softened while maintaining strength and heat resistance. On the other hand, when selected from aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and dimer acids as "other dicarboxylic acid components", the film can be formed at a smaller content ratio while maintaining the elongation (breaking elongation). Softening tends to be possible, and among them, the use of dimer acid is the most effective. Therefore, by combining and using "another dicarboxylic acid component" as described above, it is possible to obtain a film that satisfactorily combines strength, heat resistance, elongation and flexibility.

In the copolymer polyester A, the ratio of the "other dicarboxylic acid component" to the dicarboxylic acid component is preferably 5 to 20 mol%, especially 8 mol% or more or 18 mol% or less, and among them 10 mol% or more or 15 mol% or less. is more preferable. When two or more kinds of "other dicarboxylic acid components" are used together, the total amount thereof is meant.
When the ratio of the "other dicarboxylic acid component" is within the above range, the copolymer polyester film tends to be effectively softened while having good elongation, strength and heat resistance.

Examples of the above-mentioned "other alcohol components (diol components)" include 1,4-butanediol, 1,6-hexanediol, diethylene glycol, trimethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, bisphenol and their Derivatives etc. can be mentioned. Among them, diethylene glycol is preferable from the viewpoint of flexibility, and 1,4-butanediol is preferable from the viewpoint of heat resistance and strength.
Generally, when polyester is produced (polycondensed) using ethylene glycol as one of the raw materials, part of the ethylene glycol is modified into diethylene glycol and introduced into the polyester skeleton. This diethylene glycol is called by-product diethylene glycol, and the amount of the by-product is about 1 to 5 mol % of ethylene glycol, depending on the polycondensation method (ester exchange method, direct polycondensation) and the like. In the present invention, such diethylene glycol by-produced from ethylene glycol is treated as a copolymerization component and included in "other alcohol components".

In the copolymer polyester A, the ratio of the "other alcohol component (diol component)" to the alcohol component (diol component) is preferably 1 mol% or more and 50 mol% or less, especially 2 mol% or more or 40 mol% or less. It is more preferably 3 mol % or more or 30 mol % or less. Here, when two or more types of "other alcohol components" are used in combination, the total amount thereof is meant.
When the proportion of the "other alcohol component" is within the above range, the copolymer polyester film tends to be effectively softened while having good elongation, strength and heat resistance.
In addition, "another alcohol component" may use 2 or more types together. By using two or more kinds in combination, the present copolymer polyester film can be softened more effectively in some cases.

In addition, it is preferable to use three or more of "other dicarboxylic acid components" and "other alcohol components" in total. By using a plurality of copolymer components in combination, there is a tendency that the film can be softened with a smaller content ratio. In addition, if there are too many types of copolymer components, it may be difficult to stabilize the properties of the film. It is preferable that it is a seed|species, and it is especially preferable that it is 3 types or 4 types.

Copolyester A particularly preferred among the above is a copolymer of terephthalic acid, isophthalic acid and aliphatic dicarboxylic acid or dimer acid with ethylene glycol and diethylene glycol, and isophthalic acid and aliphatic dicarboxylic acid occupying dicarboxylic acid components. Alternatively, the total proportion of dimer acid is 5 mol % or more and 20 mol % or less, the proportion of diethylene glycol in the alcohol component is 1 mol % or more and 50 mol % or less, and crystalline copolyester Aa can be mentioned.
Generally, copolyesters become less crystalline when the ratio of the copolymer components is increased in order to lower the elastic modulus, and become amorphous when the ratio is further increased. The copolymer polyester Aa has a high ratio of the copolymer component and can achieve a low elastic modulus, but maintains crystallinity, so that it can be heat-set by heat treatment after stretching. As a result, the copolyester Aa is flexible, yet has good elongation and strength, and can suppress heat shrinkage.

(Resin B)
As described above, the copolyester layer (layer I) may be a layer containing copolyester A and resin B compatible therewith.
When the copolymer polyester layer (I layer) is a layer containing the copolymer polyester A and the resin B, the resin B is a resin compatible with the copolymer polyester A and has a melting point of 270 ° C. or less, or a non- A resin that is crystalline and has a glass transition temperature of 30 to 120° C. is preferred. By selecting such resin B, the glass transition temperature of the copolyester layer (layer I) can be increased, and the heat resistance can be improved. By selecting a polyester such as polyethylene terephthalate (PET) as the resin B, dimensional stability and heat resistance can be imparted.

Further, from the viewpoint of achieving both flexibility and heat resistance, the resin B contains one or more polyesters, and the polyester (including one or more polyesters) is terephthalic acid, which is a dicarboxylic acid component. and "other dicarboxylic acid components", and the alcohol component ethylene glycol and "other alcohol components", the total content of dicarboxylic acid components (when containing two or more polyesters, the dicarboxylic acid contained in each polyester The ratio of the total content of "other dicarboxylic acid components" to the total of acid components) is 5 mol% or more and 20 mol% or less, more preferably 8 mol% or more or 18 mol% or less, and more preferably 10 mol% or more or 15 mol% or less. Yes, the ratio of the total content of "other alcohol components" to the total content of alcohol components (the total of alcohol components contained in each polyester when two or more polyesters are included) is 1 mol% or more and 50 mol% or less, especially It is preferably 2 mol % or more or 40 mol % or less, and more preferably 3 mol % or more or 30 mol % or less. That is, as the component (resin B) other than the main component resin, the same resin as the resin contained in the copolyester A can be selected.

The copolyester layer (I layer) may be a layer containing copolyester A and resin D incompatible therewith.
Examples of the resin D include polycarbonate, polyolefin, polystyrene, acrylic resin, urethane resin, and the like.

In the copolymer polyester layer (I layer), the mass ratio of the copolymer polyester A and the resin B is preferably 98:2 to 50:50, especially 95:5 to 60:40, especially 90:10 to 65. :35 is more preferred.

If the component ratio of the entire polyester contained in the copolyester layer (I layer) is the same as that of the copolyester A, the same effect as when the copolyester A is included as the main component resin is obtained. It is considered possible.
Therefore, when the copolymer polyester layer (I layer) contains one or more polyesters, the total amount of all polyesters contained in the copolymer polyester layer (I layer) contains a dicarboxylic acid component. The ratio of the total content of "other dicarboxylic acid components" to the total amount is 5 mol% or more and 20 mol% or less, and the ratio of the total content of "other alcohol components" to the total content of alcohol components is 1 mol%. If the content is less than 25 mol %, the same effect as in the case of including the copolyester A as the main component resin can be obtained.
At this time, the preferred range of the ratio of the total content of the "other dicarboxylic acid components" to the total content of the dicarboxylic acid components is the ratio of the "other dicarboxylic acid components" to the dicarboxylic acid components in the copolymer polyester A. is the same as the preferred range of In addition, the preferred range of the ratio of the total content of the "other alcohol components" to the total content of the alcohol components is the same as the preferred range of the ratio of the "other alcohol components" to the alcohol components in the copolymer polyester A. is.

<In the case of laminated structure>
The present copolyester film may be a laminated film comprising a copolyester layer (I layer) and other layers, as described above.

For example, a laminated film having a configuration in which a polyester layer (II layer) containing polyester C as a main component resin is laminated on both front and back sides of a copolymer polyester layer (I layer) can be mentioned.

(Polyester C)
The polyester C is preferably a polyester having a melting point higher than the melting point of the copolymer polyester A when the copolymer polyester A is crystalline, and when the copolymer polyester A is amorphous, the copolymer polyester A polyester having a melting point higher than the glass transition point of A is preferred.

If the laminated film has such a structure, the raw material resin composition is laminated by coextrusion or the like so as to form a polyester layer (II layer)/copolyester layer (I layer)/polyester layer (II layer). In the heat setting treatment after stretching, the heat setting treatment can be performed at a higher temperature than in the case of a single copolymer polyester layer (layer I). Therefore, it is possible to achieve a level of flexibility that cannot be achieved with a single copolyester layer (layer I), to increase heat resistance, and to further prevent thermal shrinkage.

In the laminated film, the thickness of each layer of the polyester layer (layer II) is preferably 1 to 20% of the thickness of the copolymer polyester layer (layer I).
If the thickness of each layer of the polyester layer (II layer) is 1% or more of the thickness of the copolymer polyester layer (I layer), film formation is possible without greatly impairing productivity, and if it is 20% or less, it is required. It is preferable because it can ensure sufficient flexibility to be used.
From this point of view, the thickness of each layer of the polyester layer (layer II) is preferably 1 to 20% of the thickness of the copolymer polyester layer (layer I), especially 3% or more or 15% or less, especially 5% or more. Alternatively, it is more preferably 12% or less.
In addition, the thickness of the polyester layer (II layer) existing on both the front and back sides of the copolymer polyester layer (I layer) may be different on the front and back, or may be the same.

When the copolymer polyester A is crystalline, the polyester C has a melting point higher than the melting point of the copolymer polyester A by 10 to 100° C., especially 20° C. or more or 90° C. or less, especially 40° C. or more or 70° C. or less. On the other hand, when the copolymer polyester A is amorphous, the glass transition point of the copolymer polyester A is 120 to 260 ° C. higher, especially 140 ° C. or higher or 230 ° C. or lower. A polyester having a melting point higher than 160° C. or lower than 200° C. is preferred.
The polyester C, which is the main component of the polyester layer (II layer) present on both the front and back sides of the copolymer polyester layer (I layer), may be different or the same on the front and back sides. Above all, it is preferable that the melting points of the polyester C on the front and back sides are not significantly different. Specifically, the difference in melting points between the polyester layers (layer II) present on both the front and back sides is preferably 80° C. or less, preferably 60° C. or less, and more preferably 40° C. or less. When the polyester layers C on both the front and back sides of the copolymer polyester layer A are the same, co-extrusion molding of two kinds and three layers is possible, and this aspect is also preferable.

As polyester C, for example, a homopolyester or copolymer polyester containing terephthalic acid as a dicarboxylic acid component and ethylene glycol as an alcohol component can be suitably used. However, it is not limited to this.

When the polyester C is a copolymerized polyester, examples of dicarboxylic acid components other than terephthalic acid include aromatic dicarboxylic acids, alicyclic dicarboxylic acids, aliphatic dicarboxylic acids, and polyfunctional acids.
In the polyester C, the ratio of the "dicarboxylic acid component other than terephthalic acid" to the dicarboxylic acid component is preferably 1 to 30 mol%, especially 5 mol% or more or 25 mol% or less, and among them 10 mol% or more or 20 mol% or less. is more preferable.

When the polyester C is a copolymerized polyester, alcohol components other than ethylene glycol include 1,4-butanediol, 1,6-hexanediol, diethylene glycol, trimethylene glycol, neopentyl glycol, and 1,4-cyclohexane. Examples include dimethanol, bisphenol and derivatives thereof.
In Polyester C, the ratio of "alcohol components other than ethylene glycol" to the alcohol components is preferably 1 to 100 mol%, especially 5 mol% or more or 95 mol% or less, and among them 10 mol% or more or 90 mol% or less. is more preferred.

<Thickness of the present copolymer polyester film>
The thickness of the present copolymer polyester film is not particularly limited, and an appropriate thickness can be selected depending on the application.
Above all, the total thickness of the film is preferably 20 μm or more from the viewpoint of exhibiting the characteristics of the present copolymerized polyester film more effectively.
It is said that the stiffness of a film is proportional to the cube of its thickness. However, the copolyester film of the present invention has a characteristic of being weak in stiffness and flexible even when the thickness is 20 μm or more, so that the benefits of the present invention can be further enjoyed.
From this point of view, the total thickness of the copolymer polyester film is preferably 20 µm or more, more preferably 25 µm or more, and more preferably 38 µm or more.
On the other hand, the upper limit of the total thickness of the copolymer polyester film is not particularly limited. It is preferably 1000 μm or less, more preferably 500 μm or less, more preferably 250 μm or less, and more preferably 125 μm or less.

<Method for producing the present copolymer polyester film>
As an example of the method for producing the present copolymer polyester film, the case where the present copolymer polyester film is a biaxially stretched film will be described. However, it is not limited to the manufacturing method described here.

First, by a known method, raw materials such as copolyester chips are supplied to a melt extruder, heated to the melting point of each polymer or higher, the melted polymer is extruded through a die, and the glass transition point of the polymer is lowered on a rotating cooling drum. It may be cooled and solidified to the following temperature to obtain a substantially amorphous non-oriented sheet.
Next, the unoriented sheet is stretched in one direction by a roll or tenter type stretching machine. At this time, the stretching temperature is usually 25 to 120° C., preferably 35 to 100° C., and the stretching ratio is usually 2.5 to 7 times, preferably 2.8 to 6 times.
Next, the film is stretched in a direction orthogonal to the stretching direction of the first stage. At this time, the stretching temperature is usually 50 to 140° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times.
Subsequently, heat setting treatment is performed at a temperature of 130 to 270° C. under tension or under relaxation of 30% or less to obtain the present copolyester film as a biaxially oriented film.
In addition, in the above stretching, a method of stretching in one direction in two or more stages can also be employed.

The heat setting treatment (also referred to as “heat treatment”) is preferably performed at a temperature lower than the melting point of the copolymer polyester A by 10 to 70° C. when the copolymer polyester layer (I layer) is a single layer.

When the present copolymer polyester film has a laminated structure of a copolymer polyester layer (I layer) and a polyester layer (II layer), the copolymer polyester layer (I layer) and the polyester layer (II layer) are coextruded, As described above, stretching and heat setting may be performed as an integrated film.

The heat setting treatment at this time is preferably performed by heating to a temperature lower than the melting point of the polyester C. Furthermore, when the copolyester A is crystalline, it is preferable to heat-set at a temperature higher than the melting point of the copolyester A. The heat setting treatment at such a temperature enables softening to a level that cannot be achieved with a single layer of the copolyester layer (I layer).
This is because the stretching orientation of the surface layer is fixed by heat setting at a temperature lower than the melting point of the polyester C, so that the elongation, strength and heat resistance (heat shrinkability) are good, while the copolymer polyester A By heat-setting at a temperature higher than the melting point of , stretch orientation and distortion of the intermediate layer are relaxed, so that a more flexible film can be obtained.

<<Main release layer>>
This release layer contains a cationically polymerizable ultraviolet curable (hereinafter sometimes referred to as "UV cationic") silicone release agent and a photopolymerization initiator, and optionally other components, UV This is a layer made of a cationic silicone release agent composition.

<UV Cationic Silicone Release Agent Composition>
The release layer can be formed by applying a UV cationic silicone release agent composition to one or both surfaces of the copolyester film, followed by UV irradiation treatment and curing.

A UV cationic silicone release agent can be cured (cross-linked) by UV irradiation to form a release film, thereby forming a release layer exhibiting release properties with excellent thermal stability.

As the UV cationic silicone release agent, any cationic polymerizable silicone release agent that can be cured (crosslinked) by ultraviolet irradiation can be used without any particular limitation.
They may be used alone, or two or more of them may be used in combination.

The UV cationic silicone mold release agent is a modified silicone polymer component (modified polysiloxane component) is generally used alone or in combination of two or more.
In such a modified silicone-based polymer component, for example, an epoxy group (in particular, an alicyclic epoxy group, etc.) can be suitably used as the cationic polymerization reactive functional group. At least two cationic polymerization-reactive functional groups are preferably introduced into one molecule of the modified silicone-based polymer component.
The cationic polymerization-reactive functional group may be directly bonded to the silicon atom of the main chain or side chain in the modified silicone polymer component, and may be a divalent group (e.g., an alkylene group, an alkyleneoxy group, etc.). a divalent organic group, etc.).

The UV cationic silicone release agent is selected from the group consisting of γ-glycidyloxypropyl group, β(3,4-epoxycyclohexyl)ethyl group, and β(4-methyl-3,4-epoxycyclohexyl)propyl group. It preferably contains a compound having at least one epoxy group selected from among them.

In the UV cationic silicone mold release agent, a modified silicone polymer component having at least two epoxy groups in the molecule is suitably used as the modified silicone polymer component into which a cationic polymerization reactive functional group is introduced. can be done.
The modified silicone polymer component having at least two epoxy groups in the molecule is not particularly limited. For example, epoxy groups such as γ-glycidyloxypropyl group, β(3,4-epoxycyclohexyl)ethyl group, β(4-methyl-3,4-epoxycyclohexyl)propyl group are contained in the polysiloxane component of the main chain. A modified silicone-based polymer component in which at least two groups (in particular, groups containing an alicyclic epoxy group) are introduced into one molecule can be mentioned.

The epoxy group-containing group can be obtained by using, for example, "HOSi(R ₁ )(R ₂ )OH" (R ₁ is an epoxy group-containing group and R ₂ is a hydrogen atom or a hydrocarbon group) as a monomer component. It can be introduced into the molecule.

The modified silicone-based polymer component may have either a linear or branched chain configuration, or may be a mixture thereof.

Specific examples of commercially available products include X-62-7622, X-62-7629, X-62-7655, X-62-7660 manufactured by Shin-Etsu Chemical Co., Ltd., and XS56-C2244 and TPR6501S manufactured by Momentive Specialty Chemicals. , TPR6500, UV9300, UV9315, XS56-A2982, Arakawa Chemical: UVPOLY200, UVPOLY201, UVPOLY215, and the like.

<Photoinitiator>
As the photopolymerization initiator used in combination with the UV cationic silicone release agent, an onium salt photopolymerization initiator is suitable. However, a photoinitiator may be used independently and may use 2 or more types together.

As the onium salt-based photopolymerization initiator, for example, onium salts described in JP-A-6-32873, JP-A-2000-281965, JP-A-11-228702, JP-B-8-26120 A system photoinitiator etc. can be mentioned.

Among them, a diaryliodonium salt can be mentioned as an onium salt-based photopolymerization initiator.
The diaryliodonium salt has the formula: Y ₂ I ⁺ X ^- (Y represents an optionally substituted aryl group, and X ^- is a non-nucleophilic and non-basic anion; There is.) can be mentioned.
Examples of non-nucleophilic and non-basic anions of X ⁻ include SbF ₆ ⁻ , SbCl ₆ ⁻ , BF ₄ ⁻ , [B(C ₆ H ₅ ) ₄ ] ⁻ , [B(C _6H5 ) ₄ ] ^- , [B ₍ C6H4CF3) ₄ ] _- ^, [( _C6H5 ) _{2BF2 ] -} ^, _{[ C6H5BF3 ] -} ^, [ _B ( _{C6 H3F2} ) _{4 ]} ^- _{, AsF6-} ^, _PF6- ^, _HSO4- , ^{ClO4- ,} and the like.

Examples of onium salt-based photopolymerization initiators include triarylsulfonium salts, triarylselenium salts, tetraarylphosphonium salts, and aryldiazonium salts. Specific examples of these triarylsulfonium salts, triarylselenonium salts, tetraarylphosphonium salts and aryldiazonium salts are respectively "Y ₃ S ⁺ X ⁻ ", "Y ₃ S ⁺ X ⁻ " and "Y ₄ P ⁺ X ⁻ ”, and “YN ₂ ⁺ X ⁻ ” (where Y and X− are the same as above).

(Other additives)
The UV cationic silicone release agent composition contains, if necessary, a curing reaction catalyst such as a platinum-containing catalyst, a diluent solvent, and other additives in addition to the UV cationic silicone release agent and the photopolymerization initiator. can do.

Examples of the diluting solvent include aromatic hydrocarbons such as toluene; aliphatic hydrocarbons such as hexane, heptane and isooctane; esters such as ethyl acetate and butyl acetate; Examples include ketones, alcohols such as ethanol and 2-propanol, and ethers such as diisopropyl ether and dibutyl ether. These are preferably used singly or in combination in consideration of solubility, coatability, boiling point, and the like.

Moreover, you may use auxiliary agents, such as a reaction modifier and an adhesion strengthening agent, together.

<<Other Layers>>
The release film may have an "other layer" between the copolyester film and the release layer.
Examples of the "other layer" include layers having various functions such as an antistatic layer and an oligomer sealing layer.

<<Method for producing this release film>>
This release film is formed by forming a coating layer such as an antistatic layer or an oligomer sealing layer on one side or both sides of the copolymer polyester film, if necessary, and then coating these surfaces with the above UV curable silicone. It can be manufactured by applying the composition and, if necessary, curing the release layer by irradiating with ultraviolet rays.

Conventionally known coating methods such as multi-roll coating, reverse gravure coating, direct gravure coating, bar coating, and die coating can be used as methods for applying the UV cationic silicone composition. Regarding the coating method, there is an example described in "Coating Method" (published by Yuji Harasaki, Maki Shoten, 1979).

Before applying the UV cationic silicone composition, the polyester film may be subjected to a surface treatment such as corona treatment or plasma treatment.

The coating amount of the above silicone composition, that is, the thickness of the release layer (after drying), should be kept thin from the viewpoint of blocking prevention and migration (that is, the properties of the release agent component migrating to the adhesive tape, etc.). On the other hand, from the viewpoint of maintaining easy peelability (low peeling force), it is preferable to increase the thickness. Considering this point, the thickness of the release layer is preferably 0.01 to 1 g/m ² , more preferably 0.05 g/m ² or more or 0.5 g/m ² or less, and more preferably 0.05 g/m 2 or more or 0.5 g/m 2 or less. It is more preferably 05 g/m ² or more or 0.2 g/m ² or less.

When heat-treating the release layer composed of the UV cationic silicone release agent composition, a conventionally known heat treatment apparatus can be used. Examples include heating ovens, hot plates, hot air dryers, near-infrared lamps, and air dryers. Also, the heat treatment temperature is in the range of 35 to 100°C, preferably 40 to 100°C, more preferably 50 to 100°C.
Furthermore, the heat treatment time should be in the range of 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, more preferably 5 seconds to 1 minute.

When the heat-treated release layer is irradiated with ultraviolet rays, a conventionally known ultraviolet irradiation device can be used. Examples of light sources include fusion (H) lamps, metal halide lamps, high-pressure mercury lamps (ozone generating type, ozoneless type), and UV-LEDs.

Although the amount of ultraviolet irradiation is not particularly limited, it is 10 to 3000 (mJ/cm ² ), preferably 50 to 2000 (mJ/cm ² ), more preferably 100 to 1000 (mJ/cm 2 ) in terms of integrated light amount. cm ² ) is good.

<<Physical properties of this release film>>
The present release film can have the following physical properties.

<Flexibility (Koshi)>
This release film has "flexibility" (flexible) measured by the "deflection measurement method" described in the examples below, that is, the length lowered in the vertical direction (a), the horizontal direction When the protruding length is (b), the value of the ratio ((a)/(b)) between (a) and (b) is preferably 0.3 or more, especially 0.5 or more , more preferably 1.0 or more.
When (a)/(b) is 0.3 or more, it is suggested that the film has sufficient flexibility.
On the other hand, the upper limit of (a) / (b) is not particularly limited, but from the viewpoint of handling in the process, it is preferably 15.0 or less, especially 10.0 or less, and especially 6.0 or less. is more preferred.

Regarding the release film, in order to adjust (a) / (b) within the above range, it is important to first adjust the thickness of the film, and then, at the same film thickness, the release film can be achieved by adjusting the layer structure (single layer or laminate) of the present copolymerized polyester film constituting the and the type and content of the copolymerized component of the copolymerized polyester A. Furthermore, it can also be achieved by adjusting the production conditions, particularly the stretching conditions, of the copolymer polyester film.
From this point of view, it is preferable that the "other dicarboxylic acid component" of the copolymerization component of the copolymer polyester A is an aliphatic dicarboxylic acid or a dimer acid, and the content thereof is 5 mol% or more and 20 mol% or less. preferable. On the other hand, the "other alcohol component" is preferably diethylene glycol, and its content is preferably 1 mol % or more and 50 mol % or less.

<Peeling force>
In terms of the stability of the release force of the release layer, the release film has the following relationship between the normal release force (F1), the heat release force (F2), and the air exposure release force (F3) of the release layer. It is preferable to satisfy (1) and (2) at the same time.
(1)...F2-F1≤10 (mN/cm)
(2)...F3-F1≤10 (mN/cm)

Among them, it is more preferable to satisfy F2-F1 ≤ 5 (mN/cm) for (1), and further to satisfy F3-F1 ≤ 5 (mN/cm) for (2). preferable.

Here, the normal peel strength (F1) is the peel strength at 180 degrees after the adhesive tape is stuck to the surface of the release layer and allowed to stand at room temperature for 1 hour. More specifically, an acrylic adhesive tape (manufactured by Nitto Denko Corporation, No. 502) was attached to the release layer of the release film and allowed to stand at room temperature for 1 hour, and then stretched at a tensile speed of 0.3 m / min. 180° peel force measured under conditions.

The thermal peeling force (F2) is the 180° peeling force after bonding the adhesive tape to the surface of the release layer and heat-treating it at 100°C for 1 hour. More specifically, an acrylic pressure-sensitive adhesive tape (manufactured by Nitto Denko, No. 502) was attached to the release layer of the release film, heat-treated at 100 ° C. for 1 hour, and then pulled at a tensile speed of 0.3 m / min. is the 180° peel force measured under the conditions of
It is believed that this heat peel release force (F2) has a correlation with hydrogensilane groups (Si—H groups) remaining on the surface of the release layer after curing and forming on the film. A value closer to the normal peeling force (F1) indicates a smaller amount of Si—H groups remaining on the surface.

The air exposure peel strength (F3) is a 180° peel strength measured by attaching an adhesive tape after leaving the release layer at room temperature for 24 hours. More specifically, the release surface of the release layer of the release film is exposed in advance for 24 hours at room temperature, and then the release force is measured in the same manner as the normal release force (F1). .
This air exposure peel force (F3) correlates with the amount of the vinyl group (Si—CH=CH ₂ group) of the counterpart that undergoes an addition reaction with the Si—H group remaining on the surface of the release layer after being cured and formed on the film. It is believed that there is The closer the peel strength to air (F3) to the normal peel strength (F1), the smaller the amount of vinyl groups (Si—CH═CH ₂ groups) remaining on the surface.

The normal peeling force F1 of the present release film can be 35 mN/cm or less. It is preferably 30 mN/cm or less. The lower limit is 5 mN/cm or more, preferably 10 mN/cm or more, especially 15 mN/cm or more.

The heat peeling force F2 of the present release film can be 30 mN/cm or less. It is preferably 28 mN/cm or less. Also, the lower limit is 10 mN/cm or more, preferably 15 mN/cm or more.

The release force F3 exposed to air of the present release film can be 35 mN/cm or less. It is preferably 30 mN/cm or less. Also, the lower limit is 5 mN/cm or more, preferably 10 mN/cm or more, especially 15 mN/cm or more.

In the present invention, the normal peel strength (F1), the heat peel strength (F2), the air exposure peel strength (F3), and the normal peel strength (F1), which are the characteristics of the release layer, are all 30 mN / cm By keeping it within the following range, for example, when using it as a process paper in a processing process that adopts a multi-stage curing method, even if the adhesive layer that has been heat-treated is later irradiated with ultraviolet rays, the release surface and the adhesive layer However, it has the characteristic that it can be peeled off with an appropriate force without excessively heavy peeling.

<<Use of this release film>>
As described above, the present release film is excellent in flexibility, and not only is it flexible, but it is also more flexible, in other words, it has almost no stiffness. Therefore, for example, packaging materials for batteries, adhesive layer protection (OCA (Optical Clear Adhesive) component, adhesive tape protection, etc.), medical field (transdermal absorption type medicinal separator, etc.), process paper used in the manufacturing process , protection of image display members, especially for protection of structural members such as flexible displays and wearable terminals, and is suitable for applications where flexibility is required.
In addition, in the processing process, it protects the surface of a member that should not be exposed to heat of 100 ° C or more (for example, uneven molding of an adhesive layer with a low glass transition point), and the conformability to the surface of a molded product having a curved surface shape (smartphone, etc.) It is suitable as a processing paper for use in applications where the release force is required, or in processing steps employing a multistage curing system, which particularly requires the release force to be as stable as possible.
The application of the release film is not limited to the above. For example, it can be used as a process paper or a protective film for members in the manufacturing process of various packaging materials, building materials, stationery, automobile members, and other constituent members. can be done.

In addition, the release film is attached to another release film with an adhesive layer (A) to form a laminate, the release film is peeled off from the laminate, and the remaining release film with an adhesive layer ( A) is attached to the optical member, the release film is peeled off from the adhesive layer of the release film with adhesive layer (A), and the release film is again attached to the adhesive layer attached to the optical member. It is also possible to re-peel a so-called release film, which is characterized by sticking (this release film).
In addition, the release film of the release film with an adhesive layer (A) differs from the present release film in that the release force at a peel speed of 0.3 m / min is about 2 to 10 times that of the present release film. is preferred.

When using this release film for secondary processing such as adhesion processing or hard coating, the heat treatment process (a) and the ultraviolet treatment process (b) are continuously processed on the same production line. Alternatively, (a) and (b) may be processed separately on separate production lines.

<<<Explanation of terms, etc.>>>
In the present invention, the term "film" includes the "sheet", and the term "sheet" includes the "film".
In addition, the expression "panel" such as an image display panel, a protective panel, etc. includes a plate, a sheet and a film.

In the present invention, when "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, "X or more and Y or less" and "preferably larger than X" or "preferably Y It also includes the meaning of "less than".
In addition, when described as "X or more" (X is an arbitrary number), it includes the meaning of "preferably greater than X" unless otherwise specified, and is described as "Y or less" (Y is an arbitrary number). If not otherwise specified, it also includes the meaning of "preferably smaller than Y".

Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples described below.

<Evaluation method>
In the following, various physical properties were measured and evaluated as follows.

(1) normal peel strength (F1)
After sticking an adhesive tape ("No. 502" manufactured by Nitto Denko Co., Ltd.) on the surface of the release layer of the sample film, it was cut into a size of 50 mm × 300 mm, and the peel force was measured after being left at room temperature for 1 hour. did. For the peel force, "Intesco Model 2001" manufactured by Intesco Co., Ltd. was used, and 180° peeling was performed at a tensile speed of 0.3 (m/min).

(2) Heat peeling force (F2)
After sticking an adhesive tape (“No. 502” manufactured by Nitto Denko Co., Ltd.) on the surface of the release layer of the sample film, it was cut into a size of 50 mm × 300 mm and heat-treated at 100 ° C. for 1 hour in a hot air oven. did. After that, the sample was taken out, and the peel force was measured after being left at room temperature for 1 hour.
For the peel force, "Intesco Model 2001" manufactured by Intesco Co., Ltd. was used, and 180° peeling was performed at a tensile speed of 0.3 (m/min). A lower value of heat peel strength is better.

(3) Air exposed peel force (F3)
After exposing the release layer surface of the sample film for 24 hours in advance at room temperature, the peel force was measured in the same manner as the normal peel force (F1).

(4) Residual adhesion rate (migration substitute evaluation of release layer)
The sample film is cut into A4 size (210 mm × 297 mm), and a 75 μm thick biaxially stretched PET film (manufactured by Mitsubishi Chemical Corporation: Diafoil T100-75) is overlaid on the surface of the release layer, and the temperature is adjusted. It was pressed for 2 hours under conditions of 60° C. and pressure of 1 MPa. Then, the "75 μm-thick biaxially stretched PET film" was used as the migration property evaluation film.
On the other hand, the same "75 μm thick biaxially stretched PET film" as above was overlaid on an untreated PET film not provided with a release layer and pressed under the same conditions as above, and the "75 μm thick biaxially stretched PET film ” was used as the reference film.
Adhesive tape (“No. 31B” manufactured by Nitto Denko Corporation) was attached to the migration evaluation film and the reference film, cut into a size of 50 mm × 300 mm, and peeled after being left at room temperature for 1 hour. force was measured.

For the peel force, "Intesco Model 2001" manufactured by Intesco Co., Ltd. was used, and 180° peeling was performed at a tensile speed of 0.3 (m/min).
Then, the measured peeling force of the migration property evaluation film and the peeling force of the reference film were substituted into the following formula to obtain the residual adhesion rate (%).

(5) Adhesive peel strength (with or without UV)
After coating the following adhesive composition on the surface of the release layer of the sample film, it was heat-treated at 150° C. for 3 minutes to obtain an adhesive layer having a thickness after drying (DRY) of 20 μm. After that, it was laminated with a PET film to produce an adhesive layer-laminated product.
In the case of "with UV", the prepared adhesive layer-laminated product was irradiated with ultraviolet light at an integrated light amount of 500 mJ/cm ² using a "UVC-402" UV irradiation device manufactured by Ushio Inc. Then, after being stored at room temperature for one day, the sample film was peeled off from the PET film and the peel strength was measured.
On the other hand, in the case of "no UV", the laminated adhesive layer-bonded product was used as it was, and the peel force when peeling the sample film from the PET film was measured.
For the peel force, "Intesco Model 2001" manufactured by Intesco Co., Ltd. was used, and 180° peeling was performed at a tensile speed of 0.3 (m/min).

<<Adhesive composition>>
Main agent: AT352 (manufactured by Saiden Chemical Co., Ltd.) 100 parts by mass Curing agent: AL (manufactured by Saiden Chemical Co., Ltd.) 0.25 parts by mass Additive: X-301-375SK (manufactured by Saiden Chemical Co., Ltd.) 0.25 parts by mass Additive: X -301-352S (manufactured by Saiden Chemical Co., Ltd.) 0.4 parts by mass Toluene: 40 parts by mass

(6) Evaluation of suppleness (flexibility) (deflection measurement method)
Samples Samples were prepared by leaving the release films (samples) obtained in Examples and Comparative Examples in an atmosphere of 23° C. and 50% RH for 24 hours, and then cutting them into a size of 150 mm long and 50 mm wide.
As shown in FIG. 1, the release film (sample) is placed on the desk so as to protrude 50 mm from the edge of the desk in an environment of 23 ° C., and the release film (sample) on the desk is A weight of 200 g was placed and fixed on the sample), and the tip side of the sample protruding from the edge of the desk was bent downward by its own weight. After 3 minutes, measure the length (a) that the tip of the sample protruding from the edge of the desk bends vertically and hangs down, and the length (b) that the tip protrudes horizontally from the edge of the desk. did.
Then, the ratio ((a)/(b)) of the bent length (a) to the horizontally protruding length (b) was calculated. If it was less than 30, it was evaluated as "failed".

(7) Comprehensive Evaluation Flexibility and peel strength stability were evaluated according to the following evaluation criteria.
(Judgment criteria)
◯: Both flexibility and stability of peel strength are acceptable.
x: Either one of flexibility and stability of peel strength is at a failing level.

Regarding the stability of the peel strength, F2-F1 ≤ 10 (mN/cm), F3-F1 ≤ 10 ( mN/cm) at the same time was judged to be acceptable, and those not to be satisfied were judged to be unacceptable.

[material]
The following raw materials were used in Examples and Comparative Examples.

Copolyester 1 (“co-PS1”): Acid component consists of 88 mol % of terephthalic acid, 7 mol % of hydrogenated dimer acid having 36 carbon atoms and 5 mol % of isophthalic acid, and diol components consist of 90 mol % of ethylene glycol and diethylene glycol. A crystalline copolyester consisting of 10 mol %. Melting point 208°C, intrinsic viscosity 0.68 dl/g.

Copolyester 2 (“co-PS2”): acid component consisting of 88 mol % terephthalic acid and 12 mol % hydrogenated dimer acid having 36 carbon atoms, and diol component consisting of 67 mol % ethylene glycol and 33 mol % 1,4-butanediol A crystalline copolyester containing mol % (less than 0.1 mol % of by-product diethylene glycol), a melting point of 200° C., and an intrinsic viscosity of 0.72 dl/g.

[Example 1]
Copolyester 1 (co-PS1) chips were fed into a vented extruder set at 280° C. for the surface layer and intermediate layer, extruded from the die of the extruder via a gear pump and a filter, and then subjected to an electrostatic contact method. The sheet was rapidly cooled and solidified on a cooling roll whose surface temperature was set to 30° C. to obtain an unstretched sheet.
Next, the obtained unstretched sheet is stretched 3.3 times at 50 ° C. in the longitudinal direction (MD), guided to a tenter, and then stretched 4.2 times at 80 ° C. in the width direction (TD). The film was heat-treated at 200° C. for 10 seconds and relaxed 10% in the width direction (TD) to obtain a biaxially stretched copolymer polyester film having a thickness of 25 μm and substantially consisting of a single layer.
Next, a release layer composition (UV cationic silicone 1) composed of the following composition was applied so that the thickness of the coating amount (after drying) was 0.08 g / m ² , and the biaxial stretching copolymerization was performed. After applying it to the surface of the polyester film, it was dried at 70° C. for 10 seconds and then irradiated with ultraviolet rays so that the cumulative light amount was 120 mJ/m ² to obtain a release film (sample film).

(Release layer composition: UV cationic silicone 1)
UV cationic silicone release agent: TPR6500 (manufactured by Momentive Specialty Chemicals) 100 parts by mass Photopolymerization initiator: UV9380C (manufactured by Momentive Specialty Chemicals) 1 part by mass Solvent: 500 parts by mass of toluene, MEK500 parts by mass, 500 parts by mass of hexane

[Example 2]
As an intermediate layer, Copolyester 1 (Co-PS1) chips were fed into the main vented twin-screw extruder set at 280°C.
As a surface layer, polyester (PET) chips were fed into a sub-vented twin-screw extruder set at 280°C.
Through a gear pump and a filter, the polymer from the main extruder is the middle layer, and the polymer from the sub-extruder is the surface layer. An unstretched sheet was obtained by extruding and solidifying rapidly on a cooling roll whose surface temperature was set to 30° C. using an electrostatic contact method.
Next, the obtained unstretched sheet is stretched 3.2 times at 80 ° C. in the longitudinal direction (MD), guided to a tenter, and then stretched 4.0 times at 100 ° C. in the width direction (TD). Heat treated at 200° C. for 10 seconds, relaxed 10% in the width direction (TD), and having a thickness of 1 μm (surface layer) / 23 μm (intermediate layer) / 1 μm (surface layer) Biaxially stretched copolymer polyester with a thickness of 25 μm got the film.
A release layer composition similar to that of Example 1 was applied, dried, and irradiated with ultraviolet rays in the same manner as in Example 1 to obtain a release film (sample film).

[Examples 3 to 5]
A biaxially stretched copolyester film was obtained in the same manner as in Example 2, except that the conditions were changed as shown in Table 1.
In the table, for example, "co-PS1/PET = 80/20" in Example 3 means that 80 parts by mass of co-PS1 and 20 parts by mass of PET were mixed. also indicates a mass ratio.
Next, the same release layer composition as in Example 1 was applied and dried in the same manner as in Example 1, and ultraviolet rays were irradiated in the same manner as in Example 1 to obtain a release film (sample film).

[Example 6]
A release film (sample film) was obtained in the same manner as in Example 1, except that the release layer composition was changed as follows.
(Release layer composition: UV cationic silicone 2)
UV cationic silicone release agent: X-62-7660 (manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by mass Photopolymerization initiator: CAT-7605 (manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass Solvent: toluene 500 parts by mass, 500 parts by mass of MEK, 500 parts by mass of hexane

[Comparative Example 1]
A polyester (PET) chip is fed into a vented extruder set at 280°C, extruded from the nozzle of the extruder via a gear pump and a filter, and cooled with the surface temperature set to 30°C using an electrostatic contact method. It was solidified by rapid cooling on a roll to obtain an unstretched sheet.
Next, the obtained unstretched sheet is stretched 3.5 times at 86 ° C. in the longitudinal direction (MD), guided to a tenter, and then stretched 4.3 times at 110 ° C. in the width direction (TD). The film was heat-treated at 235° C. for 10 seconds and relaxed 10% in the width direction (TD) to obtain a biaxially stretched copolymer polyester film with a thickness of 50 μm.
Next, the same release layer composition as in Example 1 was applied and dried in the same manner as in Example 1, and ultraviolet rays were irradiated in the same manner as in Example 1 to obtain a release film (sample film).

[Comparative Example 2]
In Example 1, the composition of the release layer was changed to the following release layer composition, coated so that the coating amount (after drying) was 0.15 g / m ² , heat treated at 70 ° C. for 10 seconds, and then released. A mold film (sample film) was obtained.

(Release layer composition: thermosetting (solvent addition type) silicone)
Main agent: KS-847H (manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by mass Catalyst: PL-50T (manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass Solvent: 200 parts by mass of toluene, 200 parts by mass of MEK, 200 parts by mass of hexane

From the above Examples and the results of tests conducted by the inventor so far, a copolymer polyester film having a copolymer polyester layer (I layer) containing the copolymer polyester A as a main component resin is used as a base material, and one side thereof By forming a release film with a release layer obtained by applying and curing a UV cationic silicone composition to the surface, it has excellent flexibility and is not only flexible, but also more flexible.

Furthermore, as a feature of the release layer, even though it was processed at a low temperature of 100 ° C. or less, the normal peel strength (F1), the heat peel strength (F2), and the air exposure peel strength (F3) are F2 - F1 ≤ 10 ( mN/cm) and F3-F1≤10 (mN/cm), it has been found that sufficiently stable peeling properties for practical use can be obtained.
The stability of these release properties is also at a level that is difficult to achieve with conventional thermosetting silicone release agents.

It is considered that the heat peel release force has a correlation with hydrogensilane groups (Si—H groups) remaining on the surface of the release layer after the film is cured and formed. A value closer to the normal peel strength indicates a smaller amount of Si—H groups remaining on the surface.
In addition, the peel force exposed to air correlates with the amount of the vinyl group (Si—CH═CH ₂ group) of the counterpart that undergoes addition reaction with the Si—H group remaining on the surface of the release layer after being cured and formed on the film. It is believed that there are The closer the peel strength to air exposure to the normal peel strength, the smaller the amount of vinyl groups (Si--CH= _CH.sub.2 groups) remaining on the surface.

In addition, from the evaluation results of the adhesive peeling force used as a substitute evaluation of practical properties, it was found that the release film of the present invention has a small change in peeling force regardless of the presence or absence of ultraviolet irradiation (compared with Examples (comparison with Example 2).

In the present invention, by suppressing the normal state peel strength, heat peel strength, and air exposure peel strength, which are the characteristics of the release layer, within a specific range, for example, in a processing step that employs a multi-stage curing method, once heat treatment Even if the adhesive layer thus formed is irradiated with ultraviolet rays later, the release surface and the adhesive layer do not become extremely hard to release and can be peeled off with an appropriate force.

From the viewpoint of the flexibility of the release film, it was also found that good flexibility, particularly suppleness, can be obtained by devising the configuration of the copolyester film constituting the release film.
For example, as in Examples 2 to 5, when the main component resin of the intermediate layer is a crystalline copolyester, the polyester as the main component resin of the surface layer has a melting point higher than that of the copolyester. If it is polyester, it has the advantage that the heat treatment (heat setting) temperature after stretching can be made higher than in the case of a single layer consisting only of the intermediate layer.

In addition, when the main component resin of the intermediate layer is an amorphous copolyester, if the polyester as the main component resin of the surface layer has a melting point higher than the glass transition point of the copolyester, It has the advantage that the heat treatment (heat setting) temperature after stretching can be made higher than in the case of a single layer consisting only of the intermediate layer.

Claims (17)

Equipped with a copolymer polyester layer (I layer) containing as a main resin a copolymer polyester A composed of a copolymer of terephthalic acid and "other dicarboxylic acid components" and ethylene glycol and "other alcohol components" A release layer formed by curing a cationic polymerizable UV-curable silicone release agent composition is provided on at least one side of the copolyester film, and the copolyester A contains "other dicarboxylic acids" in the dicarboxylic acid component. The proportion of "component" is 5 mol% or more and 20 mol% or less, the proportion of "other alcohol component" in the alcohol component is 1 mol% or more and 50 mol% or less, and the "other dicarboxylic acid component" contains dimer acid. mold film. The cationic polymerizable UV-curable silicone release agent composition contains a γ-glycidyloxypropyl group, a β(3,4-epoxycyclohexyl)ethyl group, and a β(4-methyl-3,4-epoxycyclohexyl)propyl group. The release film according to claim 1, comprising a compound having at least one epoxy group selected from the group consisting of groups. The normal peel strength (F1), heat peel strength (F2) and air exposure peel strength (F3) of the release layer are F2-F1 ≤ 10 (mN/cm) and F3-F1 ≤ 10 (mN/cm ), the release film according to claim 1 or 2, which satisfies the relationship:
F1: 180° peel force after bonding the adhesive tape to the surface of the release layer and leaving it at room temperature for 1 hour F2: After bonding the adhesive tape to the surface of the release layer and heat treatment at 100 ° C. for 1 hour 180 ° peeling force F3: 180 ° peeling force measured by sticking an adhesive tape after leaving the release layer at room temperature for 24 hours The release film according to any one of claims 1 to 3, wherein the copolyester layer (I layer) is a layer containing the copolyester A and a resin B compatible therewith. As the resin B , one or more polyesters are included, and the polyester includes terephthalic acid as a dicarboxylic acid component and "other dicarboxylic acid components", and ethylene glycol as an alcohol component and "other alcohol components". The ratio of the total content of "other dicarboxylic acid components" to the total content of dicarboxylic acid components is 5 mol% or more and 20 mol% or less, and the total content of "other alcohol components" to the total content of alcohol components The release film according to claim 4, wherein the content ratio is 1 mol% or more and 50 mol% or less. In all the polyester contained in the copolymer polyester layer (I layer), the ratio of the total content of "other dicarboxylic acid components" to the total content of dicarboxylic acid components is 5 mol% or more and 20 mol% or less, and the alcohol component The release film according to any one of claims 1 to 5, wherein the ratio of the total content of "other alcohol components" to the total content is 1 mol% or more and 50 mol% or less. The release film according to any one of claims 1 to 6, wherein the "other dicarboxylic acid component" contains dimer acid and isophthalic acid or aliphatic dicarboxylic acid. The release film according to any one of claims 1 to 7, wherein the "other alcohol component" contains diethylene glycol. Copolyester A is a copolymer of a dicarboxylic acid component composed of terephthalic acid, isophthalic acid and dimer acid and an alcohol component composed of ethylene glycol and diethylene glycol, and the total proportion of isophthalic acid and dimer acid in the dicarboxylic acid component. is 5 mol% or more and 20 mol% or less, the ratio of diethylene glycol in the alcohol component is 1 mol% or more and 50 mol% or less, and the release film according to any one of claims 1 to 8, which is a crystalline copolyester. The release film according to any one of claims 1 to 9, wherein the dimer acid is a dicarboxylic acid composed of a dimer of unsaturated fatty acids, and the unsaturated fatty acid has 20 to 80 carbon atoms. 11. The release film according to any one of claims 1 to 10, wherein the dimer acid is a hydrogenated dimer acid obtained by dimerization with different or the same unsaturated fatty acid and then hydrogenation. It has a structure in which a polyester layer (II layer) containing polyester C as a main component resin is laminated on both the front and back sides of a copolymer polyester layer (I layer), and the polyester C is a copolymer polyester A crystal. If the copolymer polyester A is amorphous, it is a polyester having a melting point higher than the melting point of the copolymer polyester A, and if the copolymer polyester A is amorphous, it is a polyester having a melting point higher than the glass transition point of the copolymer polyester A. The release film according to any one of claims 1 to 11. The release film according to claim 12, wherein each layer thickness of the polyester layer (II layer) is 1 to 20% of the thickness of the copolymer polyester layer (I layer). The release film according to any one of claims 1 to 13, wherein the copolymer polyester film has a total thickness of 20 µm or more. The release film according to any one of claims 1 to 14, which is a process paper. The release film according to any one of claims 1 to 14, which is for protecting an adhesive layer. A laminate having a configuration in which the release film according to any one of claims 1 to 14, an adhesive layer, and another release film are sequentially laminated.

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