JP6973050B2 - Color release film and laminate - Google Patents

Description

The present invention relates to a colored release film suitable for a release film of a double-sided pressure-sensitive adhesive sheet and a laminate using this colored release film.

In recent years, the high functionality of double-sided adhesive sheets has been rapidly increasing, and they are used in a wide range of fields. As one of them, the number of cases used for building materials is increasing. For example, there are cases where it is used for airtightness during construction of a house, cases where it is used for road repair, and the like.

Release films are provided on both sides of the double-sided adhesive sheet (the release film provided on one side is referred to as a release film 1 and the release film provided on the other side is referred to as a release film 2). .. In many cases, the order in which the release film 1 and the release film 2 are peeled off is fixed. This is because the function is given to each surface of the double-sided adhesive sheet. If the order of peeling is reversed, there may be cases where the adhesive cannot be applied well or the double-sided adhesive sheet cannot perform the required functions. For this reason, in many cases, the release film 1 and the release film 2 are colored to have different colors or printed to be subjected to a process for discrimination.

Further, the release film is often required to have a small peeling force, that is, a light peeling property. The peeling force of the release film is determined by the adhesive force with the double-sided adhesive sheet and the peeling area. Therefore, as the area increases, the peeling force increases, and there is a possibility that the peeling force cannot be achieved.

Silicone resin is often used as a release agent in order to obtain a lightly peelable release film. Silicone resin is widely used as a mold release agent for products that require light peelability because it easily achieves light peelability due to its low surface free energy (Patent Document 1).

Japanese Unexamined Patent Publication No. 5-194768

Condensation type silicone resin (condensation curing type) and addition type silicone resin (addition polymerization curing type) are mainly used as silicone resins. However, since a tin catalyst is used as a curing catalyst in the condensation type silicone resin, from the viewpoint of environmental problems. It tends to be avoided from the use.
Therefore, it is desired to use a release film using an addition type silicone resin for the release layer, which has light peelability and is excellent in distinguishability and discriminability. However, if a colored polyester film is used as a base material and a release layer using an additive silicone resin is applied to the surface thereof, there is a problem that light release properties may not be exhibited or the peeling force may not be stable. Was found.

The present invention has been made in view of the above-mentioned actual conditions, and provides a colored release film having excellent discriminability and discriminability and also having excellent light peelability, and a laminate using this release film. Make it an issue.

As a result of diligent studies in view of the above problems, the present inventors have found that the above problems can be solved to a high degree by using a base film having a specific laminated structure, and have completed the present invention.

That is, the gist of the present invention is a colored release film having an additive silicone-based release layer on at least one surface of a polyester film containing a colorant, and the polyester film has at least a colored layer and a transparent layer. It exists in a colored release film having a laminated structure and having a structure in which the transparent layer is arranged between the colored layer and the addition type silicone-based release layer.

The gist of the present invention also lies in a laminated body in which a double-sided pressure-sensitive adhesive sheet is laminated on the release layer surface of this colored release film.

According to the present invention, there are provided a colored release film having excellent discriminability and discriminability and also having excellent light release property, and a laminate using this release film.

Hereinafter, the present invention will be described in detail.

[Polyester film]
The polyester film used as the base film in the colored release film of the present invention (hereinafter, may be referred to as “polyester film of the present invention”) has a laminated structure having a colored layer and a transparent layer. Further, it is preferable to have a laminated structure having three or more layers having a colored layer in the intermediate layer and transparent layers on both sides of the colored layer.

According to the present inventor, when the polyester film has a single-layer structure, a phenomenon (bleed-out) in which the colorant contained in the film springs up on the film surface in the process of forming the film, and the sublimation thereof. It was found that the phenomenon occurred. On the other hand, it was found that the addition type silicone resin used for the release layer has a very delicate curing reaction, and therefore, even if it comes into contact with a small amount of a colorant, the curing is inhibited and the curing does not proceed sufficiently. .. Therefore, it has been found that when the base film is colored with a colorant, the curing reaction of the release layer does not proceed due to the influence thereof, and the light peelability cannot be achieved or the peeling force is not stable. In particular, such a phenomenon occurs when an organic dye or pigment having a functional group, polarity, or ionicity is used as the colorant, as compared with the case of a chemically stable (inert) colorant such as carbon black. It was also confirmed that it was more prominent.
It is well known that an oligomer, which is a low molecular weight material of polyester, is present in a polyester film, and the oligomer bleeds out to the surface in the process of forming the film. Usually, in order to prevent the bleed-out of the oligomer, a curable coating layer is provided on the surface thereof. However, in order to prevent the bleed-out of the colorant, it was found that the cured layer (additional silicone-based release layer) itself, which should be a solution for preventing the bleed-out in the oligomer, is damaged. ..
From the results of the above studies, in the present invention, the polyester film has a laminated structure having at least a colored layer and a transparent layer, and a transparent layer is arranged between the colored layer and the addition type silicone-based release layer. It was solved by that.

<Polyester>
The polyester film of the present invention is preferably obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol in the polyester used for each of the laminated layers. Examples of the aromatic dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid and 2,6-naphthalenedicarboxylic acid, and aromatic dicarboxylic acid derivatives such as these lower alkyl esters. Examples of the aliphatic glycol include ethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol and the like.
Typical polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN) and the like. Among these, PET has a good balance between physical properties and cost, and is the most commonly used polyester.

The polyester used in the present invention may be a copolymerized polyester containing a third component. Examples of the dicarboxylic acid component of the copolymerized polyester include one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid and sebacic acid, and the glycol component includes ethylene glycol. , Diethylene glycol, propylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, polyethylene glycol and the like. The content of the structural unit derived from the third component with respect to all the structural units contained in the copolymerized polyester is preferably 10 mol% or less, more preferably 5 mol% or less.

The intrinsic viscosity of the polyester constituting the polyester film of the present invention is not particularly limited, but the intrinsic viscosity measured by the method described in the section of Examples described later is 0.60 to 0.75 dl / g, particularly 0. It is preferably .60 to 0.70 dl / g.

<Colored layer>
The polyester film of the present invention has a laminated structure having a colored layer and a transparent layer. Further, it is preferable that the structure has a colored layer in the intermediate layer of the laminated structure of three or more layers. This colored layer contains a colorant, and the "layer containing the colorant" and the "colored layer" are synonymous. The colorant is not limited, but preferably has absorption in the visible light region (380 to 780 nm). A compound having absorption in an ultraviolet light region or an infrared light region can also be included in the colorant in the present invention as long as the effect of the present invention is exhibited.

The colored release film of the present invention is already colored by the colored layer. Therefore, since it is not necessary to separately provide a printing layer in manufacturing the colored film, the manufacturing process can be simplified. It should be noted that the provision of a print layer on the colored release film of the present invention is not excluded. Further, the colored layer in the present invention does not have to be uniform, and may be a colored layer having a printing function.

The colorant used in the present invention is not limited, but it is preferably substantially soluble in polyester. The term "substantially dissolved" as used herein means that when the polyester is kneaded in a molten state, it is uniformly mixed without leaving any agglomerates or the like. If agglomerates or the like remain, color unevenness may occur on the polyester film.
Further, the colorant preferably has little decomposition at the molding temperature of polyester. Among them, the dye is preferable as the colorant, and anthraquinone-based, perinone-based, perylene-based, isoquinoline-based, azomethine-based, and heterocyclic dyes are more preferable in terms of chemical structure. Dispersive dyes and oil-soluble dyes are more preferable in terms of dyeing formulation.

Further, even if the colorant is generally classified as a pigment, it can be used as a colorant as long as it dissolves in the molten polyester as described above. Examples of such colorants include phthalocyanine-based copper, cobalt, nickel, zinc, and complex salt dyes with metal ions such as chromium.
Since the color release film of the present invention has a specific layer structure, the colorant can be used even when an organic dye or pigment having such a functional group, polarity, or ionicity is used as the colorant. It does not hinder the curing reaction of the addition type silicone-based release layer, and can exhibit good light peelability and stability of peeling force.

In addition to the colorant, a known ultraviolet absorber, radical trapping agent, or the like can coexist in the colored layer of the polyester film of the present invention. In this case, even if these additives are added, the film becomes turbid. It is preferable to select and use the one that does not cause the above.

The method of adding the colorant and other additives to the polyester may be a method of adding them as powder, paste, liquid or the like when the film is melt-molded, but in consideration of the problem of equipment contamination, in advance. It is preferable to prepare polyester master batches containing a colorant and the like, and add these master batches while diluting them with clear resin (polyester containing no colorant) at the time of melt molding of the film. Further, in this melt molding, it is particularly preferable to use a twin-screw extruder in order to add and knead the colorant to the polyester in a high dispersion.

The content of the colorant in the colored layer also varies depending on the thickness of the colored layer, the type of the colorant used, the concealing property and the light-shielding property by the same, and the required distinctiveness. The lower limit of the content of the colorant in the colored layer is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.4% by mass or more, and particularly preferably. Is 1.0% by mass or more. If the content of the colorant in the colored layer is less than the above lower limit, coloring with the colorant cannot be sufficiently obtained, and it is difficult to discriminate the difference from the non-colored film containing no colorant. On the other hand, the upper limit of the colorant is preferably 10% by mass or less, more preferably 5% by mass or less. If the above upper limit is exceeded, the colorant becomes a foreign substance and a colored layer, which may cause a problem during film formation.
In addition, only one kind of colorant may be used, or two or more kinds may be mixed and used. When two or more colorants are used, it is preferable that the total colorant content is within the above range.

<Transparent layer>
In addition to the colored layer, the polyester film of the present invention has a transparent layer which is a polyester film layer containing no colorant, and is arranged between the colored layer and the release layer. By having the transparent layer, it is possible to prevent the colorant contained in the colored layer from bleeding out. Further, it is preferable to have transparent layers on both sides of the colored layer. By having transparent layers on both sides of the colored layer, it is possible to improve not only the bleed-out of the colorant but also the contamination of the film forming machine and the coatability and post-processability on the side opposite to the release layer. ..
In the laminated structure of the polyester film of the present invention, the transparent layer is preferably a surface layer.

In order to facilitate handling, the transparent layer of the polyester film of the present invention may contain particles under conditions that do not impair transparency. Examples of particles used in the present invention include inorganic particles such as calcium carbonate, calcium phosphate, silica, kaolin, talc, titanium dioxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide, and crosslinked polymers. Examples include particles and organic particles such as calcium oxalate. Only one of these may be used, or two or more thereof may be used in combination.

The average particle size of the particles used is usually 0.02 to 5.0 μm, preferably 0.05 to 4.0 μm. If the average particle size is larger than 5.0 μm, the haze of the film may become too large and the transparency of the transparent layer may decrease. Although the release film of the present invention is colored, it is preferable that the haze of the transparent layer is low. If the average particle size is smaller than 0.02 μm, the surface roughness cannot be sufficiently increased, and the effect of improving the handleability of the film may not be obtained. Here, the average particle size of the particles is a value of the average particle size measured by the refractive index after being dispersed with a solvent.

When the polyester film of the present invention contains particles, the content thereof with respect to the entire laminated polyester film is usually 0.001 to 0.5% by mass, preferably 0.01 to 0.3% by mass. The particle content in the transparent layer of one layer is not particularly limited, but is preferably 0.001 to 3% by mass. When the particle content is within the above range, the haze is not increased and the minimum necessary slipperiness can be ensured, which is preferable.
Further, it is preferable that the average surface roughness Ra of the film surface of the polyester film of the present invention is within the range of 0.005 to 0.050 μm by containing particles.

Further, it is also possible to add known additives such as an infrared absorber and an ultraviolet absorber to the transparent layer of the polyester film of the present invention, if necessary.

<Thickness>
In the polyester film of the present invention, in order to surely prevent bleeding out of additives such as colorants existing in the colored layer, the thickness of the transparent layer is usually 1.0 μm or more regardless of the thickness of the entire polyester film. It is preferably 1.5 μm or more, more preferably 2.0 μm or more. The upper limit of the thickness of the transparent layer is not limited, but is usually 40 μm or less, preferably 30 μm or less, and more preferably 10 μm or less.
Further, when the transparent layers are provided on both sides of the colored layer, the thickness of each layer may be the same or different, but when the thickness of the transparent layer is different, the thickness of each of the transparent layers is within the above thickness range. It is preferable to have.

The thickness of the polyester film of the present invention (total thickness of the laminated polyester film) is usually 15 to 125 μm, particularly preferably 25 to 100 μm in terms of film handleability.

The thickness of the colored layer is not particularly limited. As described above, the thickness of the transparent layer is preferably 1.0 μm or more from the viewpoint of preventing bleed-out of colorants and the like.

[Release layer]
In the colored release film of the present invention, at least one outermost layer is an addition type silicone-based release layer in order to exhibit light release property. In the present invention, the addition-type silicone-based release layer means a layer containing an addition-type silicone resin as a main component. Here, the main component means 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more. The upper limit of the content ratio of the additive silicone resin contained in the additive silicone release layer is 100% by mass. Here, the content of the catalyst is excluded.

The addition-type silicone-based release layer is a cured layer of a composition containing an addition-type silicone resin (hereinafter, may be referred to as a “release layer-forming composition”). Here, the additive silicone resin used is not particularly limited. Further, the addition type silicone resin may be a type containing itself as a main component, or may be a modified silicone type or the like by graft polymerization with an organic resin such as a urethane resin, an epoxy resin or an alkyd resin.

The additive silicone resin comprises a polyorganosiloxane (alkenyl group-containing silicone) containing an alkenyl group as a functional group in the molecule and a polyorganosiloxane containing a hydrosilyl group as a functional group in the molecule. Is preferable.

As the polyorganosiloxane containing an alkenyl group as a functional group in the molecule, a polyorganosiloxane having two or more alkenyl groups in the molecule is preferable. Examples of the alkenyl group include a vinyl group (ethenyl group), an allyl group (2-propenyl group), a butenyl group, a pentenyl group, a hexenyl group and the like, and among them, a vinyl group and a hexenyl group are preferable. The alkenyl group is usually bonded to a silicon atom of a polyorganosiloxane forming a main chain or a side chain (for example, a silicon atom at the terminal, a silicon atom inside the main chain, or the like).

The polyorganosiloxane forming the main chain or side chain includes, for example, polyalkylalkylsiloxanes such as polydimethylsiloxanes, polydiethylsiloxanes, and polymethylethylsiloxanes, polyalkylarylsiloxanes, and silicon atoms. Examples thereof include a copolymer in which a plurality of types of monomer components are used (for example, poly (dimethylsiloxane-diethylsiloxane), etc.). Of these, polydimethylsiloxane is preferable in that stable peelability can be obtained. Specific examples of the polyorganosiloxane containing an alkenyl group as a functional group in the molecule are polydimethylsiloxane having a vinyl group as a functional group, polydimethylsiloxane having a hexenyl group as a functional group, and a mixture thereof. Will be done.

On the other hand, the polyorganosiloxane containing a hydrosilyl group as a functional group in the molecule is a polyorganosiloxane having a hydrogen atom bonded to a silicon atom (particularly, a silicon atom having a Si—H bond) in the molecule. In particular, polyorganosiloxane having two or more silicon atoms having a Si—H bond in the molecule is preferable. The silicon atom having a Si—H bond may be either a silicon atom in the main chain or a silicon atom in the side chain, that is, it may be contained as a constituent unit of the main chain and may be included in the side chain. It may be included as a constituent unit of. The number of silicon atoms in the Si—H bond is not particularly limited as long as it is two or more. As the polyorganosiloxane containing a hydrosilyl group as a functional group in the molecule, specifically, polymethylhydrogensiloxane, poly (dimethylsiloxane-methylhydrogensiloxane) and the like are suitable.

Commercially available products can also be used as the add-on silicone resin, and specific examples thereof include KS-774, KS-775, KS-778, KS-779H, KS-847H, and KS-856 manufactured by Shin-Etsu Chemical Co., Ltd. , X-62-2422, X-62-2461; DKQ3-202, DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210; manufactured by Dow Corning Asia; YSR-3022, manufactured by Toshiba Silicone. TPR-6700, TPR-6720, TPR-6721, LTC300B, LTC303E, LTC310, LTC314, SRX357, BY24-749, SD7333, BY24-179, BY24-840, BY24-842, BY24-manufactured by Toray Dow Corning. 850, SP7015, SP7259, SD7220, SD7226, SD7229 and the like can be mentioned.

A release control agent may be used in combination with the additive silicone resin as described above in order to adjust the release property of the formed release layer.

For the formation of the release layer, a catalyst is usually used in order to promote the reaction of the addition type silicone resin to form a clean and sturdy release layer. The type of catalyst used is not particularly limited, but a platinum catalyst is preferable. Platinum catalysts include platinum chloride, an alcohol solution of platinum chloride, a platinum-based compound such as a complex of platinum chloride and an olefin, a complex of platinum chloride and an alkenylsiloxane, platinum black, platinum-supported silica, and platinum-supported activated carbon. Etc. are exemplified.

Further, since the addition type silicone resin is very reactive, an addition reaction inhibitor such as acetylene alcohol may be added to the release layer forming composition in some cases. The addition reaction inhibitor is an organic compound having a carbon-carbon triple bond and a hydroxyl group, but preferably 3-methyl-1-butyne-3-ol, 3,5-dimethyl-1-hexin-3-ol and It is a compound selected from the group consisting of phenylbutinol.

The addition type silicone-based release layer in the present invention may contain a release agent other than the addition type silicone resin. The release agent other than the addition type silicone resin is not limited, and examples thereof include a condensation type silicone resin, a polyolefin-based release agent, and a fluororesin-based release agent. It is also possible to adjust the peeling force by containing a release agent other than the addition type silicone resin in the addition type silicone-based release layer. The content ratio of the release agent other than the addition type silicone resin is usually 50% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass in the addition type silicone-based release layer. % Or less. When a mold release agent other than the additive silicone resin is used, the lower limit of the content ratio is usually 1% by mass or more.

The release layer may be formed on only one side of the polyester film of the present invention, or may be formed on both sides. When the release layer is formed on both sides of the polyester film, it is preferable that the polyester film has a transparent layer on both sides of the colored layer.

The release layer is preferably formed by the coating method described later in a preferable coating amount described later.

<Other layers / surface treatment>
In the present invention, another coating layer such as an adhesive layer, an antistatic layer, and an oligomer precipitation prevention layer may be provided on the surface of the polyester film on which the release layer is not provided.
Further, the polyester film may be subjected to surface treatment such as corona treatment and plasma treatment prior to the formation of the release layer and these layers.

[Manufacturing method of colored release film]
Next, the method for producing the color release film of the present invention will be specifically described, but the method for producing the color release film of the present invention is not limited to the following production examples.

As a method for producing a polyester film of the present invention as a base film, a polyester raw material is melted from a base by laminating each polyester using a plurality of extruders, a multi-layer multi-manifold die or a feed block. A method of extruding the sheet and cooling and solidifying it with a cooling roll to obtain an unstretched sheet, that is, a coextrusion method is preferable. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and it is preferable to adopt the electrostatic application adhesion method and / or the liquid coating adhesion method.

The polyester film of the present invention may be unstretched, but is preferably a stretched film, and is particularly preferably stretched in the biaxial direction to be biaxially oriented and thermally fixed. As the stretching method, either a sequential biaxial stretching method or a simultaneous biaxial stretching method may be used. For example, when the sequential biaxial stretching method is used, the unstretched sheet is first rolled in the mechanical direction (longitudinal direction). It is stretched by a stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, stretching is performed in the width direction (lateral direction). The stretching temperature is usually 70 to 120 ° C., preferably 80 to 115 ° C., and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. Then, the heat treatment is subsequently performed at a temperature of 170 to 250 ° C. under tension or relaxation within 30% to obtain a biaxially stretched film.

In the above stretching, in addition to the method of stretching to a predetermined magnification by one stretching operation, a method of distributing the stretching into two or more stages to obtain a predetermined stretching magnification can also be used. Even in that case as well, it is preferable to make the draw ratios in the two directions finally within the above ranges. Further, if necessary, it may be stretched again in the vertical and / or horizontal directions before or after the heat treatment.

An undercoat layer may be provided on the surface of the polyester film of the present invention for the purpose of improving the adhesiveness with the release layer. The undercoat layer may be formed by coating on a polyester film that has been subjected to thermal fixation after being biaxially oriented to complete crystal orientation, but the polyester film may be stretched during film formation, especially in the mechanical direction (longitudinal). When the stretching) is completed, a coating agent diluted with a solvent mainly composed of water is applied, and then the polyester film is oriented and crystallized during lateral stretching and heat fixing, and the undercoat layer is added by drying the coating agent. It is more preferable that the coating is performed by a method using a so-called in-line coating, which is performed at the same time.

As a method of applying the release layer forming composition to the polyester film of the present invention to provide the release layer, a conventionally known coating method such as a reverse roll coat, a gravure coat, a bar coat, and a doctor blade coat is used. Can be done. The release layer forming composition may be applied by either an in-line coat or an offline coat. The coating amount of the release layer forming composition is usually in the range of ^{0.01 to 1 g / m 2 as the coating amount after drying.}

The coating film of the release layer forming composition can be dried and cured individually or simultaneously. The temperature condition is preferably 80 ° C. or higher, for example, 100 to 180 ° C. When the temperature is 80 ° C. or higher, the coating film is sufficiently cured and the coating film can be prevented from falling off. Further, the curing time is preferably 10 seconds or more, for example, 20 to 90 seconds from the viewpoint of curing the coating film.

Further, when the release layer is provided as the outermost layer, as described above, the surface of the polyester film of the present invention may be subjected to surface treatment such as corona treatment and plasma treatment in advance. If necessary, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination.

[Physical characteristics of colored release film]
<Visible light transmittance>
The visible light transmittance of the colored release film of the present invention is preferably in the range of 3 to 90%, more preferably in the range of 5 to 80%. When the visible light transmittance is 3% or more, good clarity and distinctiveness due to coloring can be obtained. If the visible light transmittance exceeds 90%, coloring may not be visible when the film is used alone.
The visible light transmittance of the colored release film is measured by the method described in the section of Examples described later.

<Normal peeling force>
The release layer of the colored release film of the present invention is preferably lightly peelable, and the normal release force is preferably 50 mN / cm or less, more preferably 40 mN / cm or less, and even more preferably 35 mN / cm or less. If the normal peeling force exceeds 50 mN / cm, the release film may not be manually peeled off during construction due to the enormous area. The lower limit of the normal peeling force is usually 10 mN / cm or more.

Here, the normal peeling force means that a double-sided adhesive tape (Nitto Denko Co., Ltd., No. 502) is attached to the surface of the release layer of the colored release film, left at room temperature for 1 hour, and then the release angle is 180 ° and any tensile strength is used. The value measured by a tensile tester when the tape is peeled off at a high speed. The specific method for measuring the normal peeling force is as described in the section of Examples described later.

The method for adjusting the peeling force of the colored release film of the present invention is conditional on the release layer containing an additive silicone resin, but is not particularly limited to other methods. Examples of the method for adjusting the peeling force include a method for adjusting the type and coating amount of the additive silicone resin, which is a release agent used for the release silicone release layer, the thickness of the release layer, and the like.

<Heat peeling force>
The heat release force of the color release film is preferably 125 mN / cm or less, more preferably 100 mN / cm or less. The lower limit of the heat peeling force is usually 10 mN / cm or more. Here, the heat peeling force means that a double-sided adhesive tape (Nitto Denko Co., Ltd., No. 502) is attached to the surface of the release layer of the colored release film, left in an oven at 100 ° C. for 1 hour, and at room temperature (23). The value measured by a tensile tester when the tape is peeled off at an arbitrary tensile speed with a peeling angle of 180 ° after cooling to (° C.). The specific method for measuring the heat peeling force is as described in the section of Examples described later.

<Heat peeling force / normal peeling force ratio>
In the colored release film of the present invention, the ratio of the heat peeling force to the normal peeling force (heat peeling force / normal peeling force) is preferably 2.5 or less, more preferably 2.0 or less.
Usually, the release film changes its peeling force by heating. One of the factors that change the heat peeling force is that the release layer is not sufficiently cured. If the ratio of the heat peeling force to the normal peeling force exceeds 2.5, the release layer may not be sufficiently cured, and the silicone resin may fall off from the polyester film. The lower limit of the heat peeling force / normal peeling force ratio is preferably 1.0 or more.
Since the colored release film of the present invention can suppress the inhibition of curing of the release layer by the colorant, the curing reaction of the release layer can be completed, and the change between the heat release force and the normal release force can be changed. It can be suppressed.

[Double-sided adhesive sheet]
The method of using the colored release film of the present invention is not limited, but it can be suitably used as a double-sided pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is laminated.
The material constituting the pressure-sensitive adhesive layer is not limited, and known pressure-sensitive adhesives can be used.

In the case of a laminated film in which a release film is laminated on both sides of a double-sided pressure-sensitive adhesive sheet, the colored release film of the present invention may be used as the release film on both sides, but one side is used as the colored release film of the present invention. As described above, it is preferable that the other surface is a release film that does not contain a colored layer in order to distinguish between the release film 1 and the release film 2. When the release force of the release film 1 and the release film 2 are different, it is arbitrary which release film the colored release film of the present invention is used, but the release film of the present invention is stable. Since it has a light release property, it can be suitably used on the side having a low release force.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded.

[Evaluation of physical properties / characteristics]
In the following, various physical properties and characteristics are measured or defined as follows.

(1) Measurement of Intrinsic Viscosity of Polyester 1 g of polyester from which the colorant was removed was precisely weighed, 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (mass ratio) was added and dissolved, and the measurement was carried out at 30 ° C.

(2) Visible light transmittance For the sample film, measure the light transmittance at each wavelength of 380 to 780 nm with a D65 light source using a spectroscopic colorimeter (manufactured by Nippon Denshoku Co., Ltd., SE-2000), and comply with JIS-S3107. The visible light transmittance was calculated.

(3) Normal peeling force An adhesive tape (Nitto Denko Co., Ltd., No. 502) was attached to the surface of the release layer of the sample film, and the peeling force after being left at room temperature for 1 hour was measured. The peeling force was measured by performing 180 ° peeling under the condition of a tensile speed of 300 mm / min using a tensile tester (Intesco model 2001 type manufactured by Intesco).

(4) Heat peeling force Adhesive tape (Nitto Denko Co., Ltd., No. 502) was attached to the surface of the release layer of the sample film, left in an oven at 100 ° C for 1 hour, and cooled to room temperature (23 ° C). The peeling force of was measured. The peeling force was measured by performing 180 ° peeling under the condition of a tensile speed of 300 mm / min using a tensile tester (Intesco model 2001 type manufactured by Intesco).

(5) Love-off test (evaluation of practical characteristics substitute)
The sample film was left in a room at 23 ° C. and 50% RH for 30 days, and then the release layer surface was rubbed with a fingertip several times. Based on the state of the surface of the release layer after rubbing, it was evaluated according to the following criteria.
"criterion"
◯: Good with no change on the surface of the release layer (no problem in practical use)
×: Traces of rubbing with a finger were seen on the surface of the release layer (there is a problem in practical use).

(6) Film discrimination test (evaluation of practical characteristics substitute)
A sample film and a general-purpose release film (Diafoil MRF25 manufactured by Mitsubishi Chemical Corporation) were prepared. Ten testers were randomly selected to select colored films. Whether or not it can be discriminated was evaluated according to the following criteria.
"criterion"
◯: 10 out of 10 selected the sample film (discrimination performance is very high).
Δ: 8 to 9 out of 10 selected the sample film (has discrimination performance).
X: 7 or less out of 10 selected the sample film (no discrimination performance)

(7) Peeling test (evaluation of practical characteristics substitute)
An acrylic pressure-sensitive adhesive composition prepared as described below was applied to the surface of the release layer of the sample film, and then heat-treated at 100 ° C. for 5 minutes to form a pressure-sensitive adhesive layer having a thickness (after drying) of 150 μm. Next, the surface of the adhesive layer was attached to a glass plate, and whether or not it could be peeled off by hand was evaluated according to the following criteria.
<Acrylic adhesive composition>
(Monomer mixture)
2-Ethylhexyl acrylate: 70% by mass
2-Methoxyethyl acrylate: 29% by mass
4-Hydroxybutyl acrylate: 1% by weight
An acrylic pressure-sensitive adhesive composition was prepared by adding 0.1 part by mass of polyisocyanate (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) to 100 parts by mass of the above-mentioned monomer mixture.
"criterion"
◯: Can be easily peeled off (no problem in practical use)
×: Cannot be easily peeled off (there is a problem in practical use)

(8) Comprehensive evaluation Comprehensive evaluation was performed for each evaluation item of the love-off test, film discrimination test, and peeling test according to the following criteria.
"criterion"
○: All of the love-off test, film discrimination test, and peeling test are ○ or △
×: At least one of the love-off test, film discrimination test, and peeling test is ×

[Manufacturing of polyester]
The polyester used in Examples and Comparative Examples was produced as follows.

<Polyester A>
100 parts by mass of dimethyl terephthalate, 60 parts by mass of ethylene glycol and 0.09 part by mass of magnesium acetate tetrahydrate were taken in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction for 4 hours from the start of the reaction. The temperature was raised to 230 ° C., and the transesterification reaction was substantially completed. Then, after adding 0.04 part by mass of ethyl acid phosphate and 0.04 part by mass of antimony trioxide, the temperature was set to 280 ° C. and the pressure was set to 15 mmHg in 100 minutes, and the pressure was gradually reduced thereafter, and finally. It was set to 0.3 mmHg. After 4 hours, the pressure inside the system was returned to normal pressure to obtain polyester A containing substantially no fine particles. The intrinsic viscosity of polyester A was 0.70 dl / g.

<Polyester B>
After the transesterification reaction was completed, an ethylene glycol slurry containing 2.0 parts by mass of silica particles having an average particle size of 1.4 μm was added, and 0.04 parts by mass of ethyl acid phosphate and 0.04 parts by mass of antimony trioxide were further added. Was added, but the same method as for polyester A was used to obtain polyester B. The silica particle content of the obtained polyester B was 1.0% by mass. The intrinsic viscosity of polyester B was 0.70 dl / g.

<Polyester C>
After the transesterification reaction was completed, polyethylene glycol having a molecular weight of 6000 (containing 0.3% by mass of an antioxidant) was added as an ethylene glycol solution, and 0.04 parts by mass of ethyl acid phosphate and 0.04 parts by mass of antimony trioxide were further added. Polyester C was obtained by producing in the same manner as in polyester A except that the portion was added. The intrinsic viscosity of polyester C was 0.70 dl / g.

<Polyester D>
Polyester A was used in a twin-screw extruder with a vent, and dial resin red HS (manufactured by Mitsubishi Chemical Corporation, perinone dye) was 3.0% by mass, and dial resin blue H3G (manufactured by Mitsubishi Chemical Corporation, anthraquinone dye) was 5 .5% by mass and dialresin yellow F (isoquinoline dye manufactured by Mitsubishi Chemical Corporation) are mixed and added to each concentration of 1.5% by mass, and melt-kneaded to form chips, and the dye is formed. Polyester D was created as a masterbatch.

<Polyester E>
Polyester A was used in a twin-screw extruder with a vent, and dial resin red HS (manufactured by Mitsubishi Chemical Corporation, perinone dye) was 1.0% by mass, and dial resin blue H3G (manufactured by Mitsubishi Chemical Corporation, anthraquinone dye) was 5 .5% by mass and dialresin yellow F (isoquinoline dye manufactured by Mitsubishi Chemical Corporation) are mixed and added to a concentration of 3.5% by mass, and melt-kneaded to form chips, and the dye is formed. Polyester E was created as a masterbatch.

[Composition for forming a release layer]
In the following Examples and Comparative Examples, for the formation of the release layer, a mixture containing a non-volatile component according to the formulation shown in Table 1 below as a release layer forming composition is used as a toluene / methyl ethyl ketone mixed solvent (mixing ratio is 1: 1). The coating liquids 1 to 3 prepared by diluting in 1) were used.
(A1) Addition type silicone resin (KS-847H: manufactured by Shin-Etsu Chemical Co., Ltd.)
(A2) Additive silicone resin (LC303E: manufactured by Toray Dow Corning)
(B1) Heavy peel control agent (SD-7292: manufactured by Toray Dow Corning)
(C1) Platinum catalyst (PL-50T: manufactured by Shin-Etsu Chemical)

[Manufacturing of polyester film]
The polyester films used in the following examples and comparative examples were produced as follows.

<Manufacturing of polyester film F1>
As an intermediate layer, a mixture of polyesters A and D at a mass ratio of 78:22 was charged into an extruder as a resin for an intermediate layer. Further, as the surface layers on both sides of the intermediate layer, a mixture of polyesters A, B, and C at a mass ratio of 77: 10: 13 was charged into an extruder as a surface layer resin. Each extruder was a non-directional twin-screw extruder with a vent, and the resin was extruded at a melting temperature of 290 ° C. without drying, and then the molten polymers were merged and laminated in a feed block. Then, it was cooled and solidified on a cooling roll whose surface temperature was set to 40 ° C. using an electrostatic application adhesion method to obtain a laminated unstretched sheet having a three-layer structure.

The obtained laminated unstretched sheet was stretched 3.6 times in the mechanical direction (longitudinal direction) at 83 ° C. Further, the film was guided to a tenter, dried and preheated at 93 ° C., then stretched 3.8 times in the width direction (lateral direction), and heat-fixed at 225 ° C. Further, a 5% relaxation treatment was performed at 185 ° C. in the width direction to obtain a polyester film F1.
The polyester film F1 was a three-layer laminated film in which the intermediate layer was a colored layer and the surface layer was a transparent layer, and the thickness of each layer was 2 μm / 21 μm / 2 μm, and the total thickness was 25 μm.

<Manufacturing of polyester film F2>
As the intermediate layer, the polyester film F2 was obtained by producing the polyester film F1 in the same manner as the polyester film F1 except that the polyester D was changed to the polyester E.

<Manufacturing of polyester film F3>
The polyester film F3 was produced in the same manner as the polyester film F1 except that the polyesters A and D used for the intermediate layer were mixed at a mass ratio of 90:10.

<Manufacturing of polyester film F4>
The polyesters A and D used for the intermediate layer were mixed in a mass ratio of 95.5: 4.5, and the polyester film F4 was obtained in the same manner as the polyester film F1.

<Manufacturing of polyester film F5>
As an intermediate layer, a mixture of polyesters A, B, and C at a mass ratio of 77.0: 10.0: 13.0 was charged into an extruder as an intermediate resin. Further, as a surface layer, a mixture of polyesters A and D at a mass ratio of 78:22 was charged into an extruder as a surface layer resin.
A polyester film F5 was obtained by producing the polyester film F1 in the same manner as the polyester film F1 except for the above.
The polyester film F5 was a three-layer laminated film in which the intermediate layer was a transparent layer and the surface layer was a colored layer, and the thickness of each layer was 2 μm / 21 μm / 2 μm, and the total thickness was 25 μm.

<Manufacturing of polyester film F6>
As the surface layer, the polyester film F6 was obtained by producing the polyester film F5 in the same manner as the polyester film F5 except that the polyester D was changed to the polyester E.

<Manufacturing of polyester film F7>
A polyester film F7 was obtained by the same method as that of the polyester film F1 except that 100% by mass of the polyester A was used as the intermediate layer.
The polyester film F7 was a three-layer laminated film in which all layers were transparent layers.

[Example 1]
On the surface layer of the polyester film F1 having a thickness of 25 μm, the coating liquid 1 was applied as a release layer forming composition to a coating amount of 0.1 g / m ² after drying by an offline reverse gravure coating method. After coating, it was heated and dried at 150 ° C. for 30 seconds and cured to form a release layer. The characteristics of the obtained release film are shown in Table 2.

[Example 2]
A release film was obtained in the same manner as in Example 1 except that the polyester film F1 was changed to the polyester film F2. The characteristics of the obtained release film are shown in Table 2.

[Example 3]
A release film was obtained in the same manner as in Example 1 except that the coating liquid 1 was changed to the coating liquid 2. The characteristics of the obtained release film are shown in Table 2.

[Example 4]
A release film was obtained in the same manner as in Example 1 except that the coating liquid 1 was changed to the coating liquid 3. The characteristics of the obtained release film are shown in Table 2.

[Example 5]
A release film was obtained in the same manner as in Example 4 except that the polyester film F1 was changed to the polyester film F2. The characteristics of the obtained release film are shown in Table 2.

[Example 6]
A release film was obtained in the same manner as in Example 4 except that the polyester film F1 was changed to the polyester film F3. The characteristics of the obtained release film are shown in Table 2.

[Example 7]
A release film was obtained in the same manner as in Example 1 except that the polyester film F1 was changed to the polyester film F4. The characteristics of the obtained release film are shown in Table 2.

[Comparative Example 1]
A release film was obtained in the same manner as in Example 1 except that the polyester film F1 was changed to the polyester film F5. The characteristics of the obtained release film are shown in Table 3. Since the surface layer of the polyester film F5 is a colored layer, the release layer was insufficiently cured due to the inhibition of curing by the colorant, and the love-off test failed.

[Comparative Example 2]
A release film was obtained in the same manner as in Example 1 except that the polyester film F1 was changed to the polyester film F6. The characteristics of the obtained release film are shown in Table 3. Since the surface layer of the polyester film F6 is a colored layer, the release layer was insufficiently cured due to the inhibition of curing by the colorant, and the love-off test failed.

[Comparative Example 3]
A release film was obtained in the same manner as in Example 1 except that the polyester film F1 was changed to the polyester film F7. The characteristics of the obtained release film are shown in Table 3. Since all the layers of the polyester film F7 are transparent layers, the film discrimination test failed.

Claims (6)

A coloring release film having an addition type silicone-based release layer on at least one surface of a polyester film containing a colorant, wherein the polyester film has a laminated structure having at least a coloring layer and a transparent layer, and Ri configuration der that the transparent layer is disposed between the colored layer and the addition type silicone release layer, according to JIS-S3107, the visible light transmittance (380 to 780 nm) is 5% to 80% A characteristic colored release film. The colored release film according to claim 1, wherein the polyester film has a laminated structure of three or more layers having a colored layer as an intermediate layer and transparent layers on both sides thereof. The colored release film according to claim 1 or 2, wherein the colored layer contains 0.01% by mass or more of a colorant. The colored release film according to claim 3, wherein the colorant absorbs in the visible light region (380 to 780 nm). The colored release film according to any one of claims 1 to 4 , wherein the colorant is at least one selected from anthraquinone-based, perinone-based, perylene-based, isoquinoline-based, azomethine-based, and heterocyclic-based. A laminate obtained by laminating a double-sided adhesive sheet on the release layer surface of the color release film according to any one of claims 1 to 5.