Method for producing release film

Abstract

To provide a method for manufacturing release film, which imparts detachability of practical use as release film, and which is superior in a property of adhering to a substrate.SOLUTION: Provided is a method for manufacturing release film. The method includes: (1) a step for obtaining a laminate comprising a coating layer by coating a coating liquid containing a solventless silicone release agent of an addition reaction type, on a PET-based substrate; (2) a pre-irradiation step for irradiating the coating layer of the laminate with ultraviolet rays so that an integrated light volume is 8-1400 mJ / m2; and (3) a step for forming a release layer obtained by heating the laminate and reaction-curing the coating layer, after step (2).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a release film. [Background technology]

[0002] Release films are used as adhesive labels, carrier sheets for producing resin sheets, various protective sheets, etc. Such release films are formed by providing a release layer composed of a silicone-based release agent or the like on a substrate such as paper or plastic film. Such release films are produced by using a solvent-based silicone-based release agent containing an organic solvent in a coating liquid, applying this to a substrate such as a plastic film, and heating the coating liquid to form a release layer on the substrate.

[0003] As a method for producing such a release film, Patent Document 1 discloses a release film having a sheet-like substrate and a cured layer of an addition reaction type silicone resin composition containing a photosensitizer provided thereon, wherein the cured layer is formed by heating an addition reaction type silicone resin composition layer containing at least one photosensitizer selected from α-hydroxyketones and α-diketone dialkyl acetals, followed by ultraviolet irradiation treatment. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-205746 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although it is possible to reduce the amount of organic solvent used in the coating liquid for forming the release layer and use a solvent-free silicone release agent or the like, in this case, there is a problem that sufficient adhesion to the substrate cannot be obtained, and it is difficult to achieve the releasability required for a release film. Such a problem is remarkable when a polyethylene terephthalate-based substrate is used, and for example, a problem occurs in which the release agent falls off even when the surface of the release layer is lightly rubbed.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a method for producing a release film that can impart practical releasability to the release film and has excellent adhesion to the substrate. [Means for solving the problem]

[0007] As a result of extensive research into achieving the above-mentioned object, the present inventors have discovered a method for producing a laminate including a coating layer by applying a coating solution containing an addition reaction type solventless silicone release agent to a polyethylene terephthalate substrate, and by applying an integrated light dose of 8 to 1400 mJ / m to the coating layer of the laminate. 2 The present inventors have discovered that a pre-irradiation step involves irradiating the laminate with ultraviolet light so that the coating layer becomes uniform, and that after steps (3)(2), the laminate is heated to react and cure the coating layer, thereby forming a release layer, and have completed the present invention.

[0008] That is, the present invention is as follows.

[0009] [1] (1) applying a coating solution containing an addition reaction type solventless silicone release agent to a polyethylene terephthalate substrate to obtain a laminate including a coating layer; and (2) exposing the coating layer of the laminate to an integrated light dose of 8 to 1400 mJ / m. 2 and (3) after step (2), a step of heating the laminate to reactively cure the coating layer and form a release layer. [2] In the method for producing a release film according to [1], the process (3) is a process in which, after the process (2), the laminate is heated and then further irradiated with ultraviolet light to reactively harden the coating layer and form a release layer. [3] The method for producing a release film according to [1] or [2], wherein the coating liquid containing the solventless silicone release agent exhibits a weight loss rate of 8.0% by mass or less at 150°C when heated from room temperature to 170°C at a heating rate of 10°C / min. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for producing a release film that can impart releasability that allows it to be used as a release film and that has excellent adhesion to a substrate. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0012] The method for producing a release film according to this embodiment includes the steps of: (1) applying a coating solution containing an addition reaction type solventless silicone release agent to a polyethylene terephthalate substrate to obtain a laminate including a coating layer; and (2) exposing the coating layer of the laminate to an accumulated light dose of 8 to 1400 mJ / m. 2 The method for producing a release film includes a pre-irradiation step of irradiating the laminate with ultraviolet light so that the coating layer becomes a release layer, and a step (3) after the step (2), of heating the laminate to reactively cure the coating layer and form a release layer. Note that the term "film" in this specification also encompasses what is called a "sheet." Therefore, the "release film" in this embodiment also encompasses what is called a "release sheet," etc.

[0013] Here, an example of a conventional release film using a silicone release agent will be described. In order to ensure coatability and obtain a thin coating film, and to ensure adhesion to the substrate, a solvent-based silicone release agent diluted with an organic solvent is sometimes used. Furthermore, from the viewpoint of minimizing migration after curing, addition reaction type silicone release agents are sometimes used among silicone release agents.

[0014] In these conventional methods, attempts have been made to use solventless silicone release agents instead of solvent-based silicones as a production method that minimizes the use of organic solvents, taking into consideration the impact on the environment, but this creates the problem of poor adhesion to the substrate. This problem can become particularly pronounced when an addition-reaction type solventless silicone release agent is combined with a polyethylene terephthalate-based substrate.

[0015] In addition, in conventional methods such as diluting the release agent by adding an organic solvent to prepare a coating liquid or using a solvent-based silicone release agent that has a predetermined amount of organic solvent pre-blended, there are restrictions on irradiating ultraviolet light in the presence of a solvent from a safety standpoint. For example, if ultraviolet light is irradiated in a solvent-containing state, the evaporation of the solvent may cause the explosion limit to be exceeded in the ultraviolet irradiation device. For these reasons, in the conventional methods described above, ultraviolet light irradiation cannot be performed before heating, or irradiation before heating is avoided. For these reasons, it has been considered unrealistic to use an addition reaction-type solventless silicone release agent on a polyethylene terephthalate substrate to produce a release film that can withstand practical use.

[0016] Taking these points into consideration, the present inventors changed their thinking and conducted extensive research into incorporating a solventless silicone release agent into the coating liquid and applying this coating liquid to a polyethylene terephthalate substrate. They then came up with the idea of ​​pre-irradiating the coating with ultraviolet light under specific conditions before heating, and completed the manufacturing method of this embodiment. In other words, the present inventors discovered that even with an addition-reaction type solventless silicone and a polyethylene terephthalate substrate, a combination that is considered to be poor in terms of adhesion, etc., it is possible to achieve both releasability as a release film and adhesion to the substrate.

[0017] Hereinafter, each process that can be carried out in this embodiment and materials that can be used will be described by way of example.

[0018] <Coating process>

[0019] (1) A coating solution containing an addition reaction type solventless silicone release agent is applied to a polyethylene terephthalate substrate (PET substrate) to obtain a laminate including a coating layer.

[0020] (Polyethylene terephthalate base material (PET base material))

[0021] In this embodiment, a PET-based substrate is used as the film substrate. The PET-based substrate is a substrate containing polyethylene terephthalate (PET), and is preferably a polyethylene terephthalate substrate. The polyethylene terephthalate may be stretched or unstretched, and for example, biaxially stretched polyethylene terephthalate or the like can be suitably used.

[0022] The PET substrate may be a single layer consisting of only one layer, or may be a multi-layer consisting of two or more layers. In the case of a multi-layer structure, it is sufficient that the layer to which the coating liquid is applied (the outermost layer of the substrate) is a polyethylene terephthalate substrate. For example, it may be a laminate composed of multiple layers of PET substrates.

[0023] The thickness of the PET substrate is not particularly limited, but is preferably 2 to 500 μm. The upper limit of this thickness is more preferably 250 μm or less, and even more preferably 188 μm or less. The lower limit of this thickness is more preferably 10 μm or more, and even more preferably 15 μm or more.

[0024] (Addition reaction type solventless silicone release agent)

[0025] In this embodiment, the solventless silicone release agent of the addition reaction type may contain, for example, a low-molecular-weight silicone such as a reactive diluent. Low-molecular-weight silicones may volatilize slightly at high temperatures. In this embodiment, a preferred aspect of the "solventless (system)" is that when the temperature is increased from room temperature to 170°C at a rate of 10°C / min, the weight loss rate at 150°C is 8.0% by mass or less. This weight loss rate can serve as an indicator of the degree of solventlessness, and is more preferably 6.0% by mass or less, even more preferably 5.0% by mass or less, and even more preferably 0% by mass. While the content loss rate is preferably 0% by mass, the lower limit may exceed 0% by mass, as long as the effects of this embodiment are achieved. Therefore, for example, the solventless silicone release agent of the addition reaction type described above may not contain an organic solvent, but the weight loss rate may be within the above-mentioned numerical range.

[0026] The weight loss rate (%) can be calculated by applying the weight at 150°C ("weight at 150°C") and the weight before heating ("weight before heating") to the following formula when the temperature is raised from room temperature to 170°C at a heating rate of 10°C / min. Weight loss rate (%) = (weight before heating - weight at 150°C) / weight before heating × 100

[0027] A preferred example of an addition reaction type silicone release agent is a release agent containing (a) a polyorganosiloxane having at least one addition reactive group per molecule and (b) a polyorganosiloxane having at least one hydrosilyl group per molecule. The addition reactive group of component (a) can be an alkenyl group. The addition reactive group of component (a) and the hydrosilyl group of component (b) react and cure through a hydrosilylation reaction or the like to form a release layer with sufficient releasability for practical use as a release film, and the release layer can also be adhered to a PET substrate.

[0028] Furthermore, it is more preferable that the solventless silicone release agent used in the coating liquid contains (a) an alkenyl group-containing polyorganosiloxane containing an alkenyl group having 2 to 10 carbon atoms, and (b) a hydrosilyl group-containing polyorganosiloxane containing a hydrosilyl group. By using such a combination, the viscosity can be kept to a level that allows coating without dilution with a solvent, and components (a) and (b) can be sufficiently reacted and cured to form a release layer.

[0029] Examples of component (a) include vinyl group-containing polyorganosiloxanes, allyl group-containing polyorganosiloxanes, butenyl group-containing polyorganosiloxanes, pentenyl group-containing polyorganosiloxanes, hexenyl group-containing polyorganosiloxanes, heptenyl group-containing polyorganosiloxanes, octenyl group-containing polyorganosiloxanes, nonenyl group-containing polyorganosiloxanes, and decenyl group-containing polyorganosiloxanes.

[0030] The (b) component can be a crosslinking agent, such as a hydrosilyl-containing polyorganosiloxane having one or more, preferably two or more, silicon-bonded hydrogen atoms in the molecule. Specific examples include hydrosilyl-containing polyorganosiloxanes such as polymethylhydrogensiloxane, polyethylhydrogensiloxane, poly(dimethylsiloxane-methylhydrogensiloxane), dimethylhydrogensiloxy-endblocked dimethylsiloxane-methylhydrogensiloxane copolymer, trimethylsiloxy-endblocked dimethylsiloxane-methylhydrogensiloxane copolymer, trimethylsiloxy-endblocked poly(methylhydrogensiloxane), and poly(hydrogensilsesquioxane).

[0031] The addition reaction type solventless silicone release agent of this embodiment can be any commercially available solventless silicone release agent, and examples of commercially available products that can be used include "DOWSIL™ LTC1057L," "LTC1067M," and "(Dow-Toray Industries, Inc.)" (all manufactured by Dow-Toray Industries, Inc.); "KNS 3056," "KNS 320A," and "X-62-1387" (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0032] The content of component (b) relative to component (a) is not particularly limited as long as it is controlled to a ratio that allows a curing reaction, but it is preferably 0.1 to 100 parts by mass, and more preferably 0.3 to 50 parts by mass, per 100 parts by mass of component (a).

[0033] Examples of the polyorganosiloxane skeleton of components (a) and (b) include polyalkylalkylsiloxanes such as polydimethylsiloxane, polydiethylsiloxane, and polymethylethylsiloxane; polyalkylarylsiloxanes; etc. Among these, polydimethylsiloxane is preferred.

[0034] The skeleton of the polyorganosiloxane may be a modified polyorganosiloxane in which one or more organic groups are bonded to silicon atoms (Si) etc. Examples of the organic group include an amino group, a silanol group, an acrylic group, a methacrylic group, an epoxy group, and a carboxyl group.

[0035] The coating liquid preferably contains a platinum-based catalyst. Specific examples of platinum-based catalysts include fine particle platinum, fine particle platinum adsorbed on a carbon powder support, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, and platinum group metal compounds such as palladium and rhodium. The catalyst content is not particularly limited, but is preferably 1 to 10 parts by mass per 100 parts by mass of the total amount of components (a) and (b). The upper limit is more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less.

[0036] The coating liquid may further contain a sensitizer, if necessary. The sensitizer is not particularly limited, and any sensitizer commonly used in ultraviolet resin curing, as described below, can be used. Specific examples of sensitizers include benzoins, benzophenones, acetophenones, α-hydroxyketones, α-aminoketones, α-diketones, α-diketone dialkyl acetals, anthraquinones, thioxanthones, and other compounds.

[0037] Examples of benzoins include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, and compounds in which benzoin is ether-bonded to both ends of polydimethylsiloxane.

[0038] Examples of benzophenones include benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, trimethylsilylated benzophenone, and 4-methoxybenzophenone.

[0039] Examples of acetophenones include acetophenone, dimethylaminoacetophenone, 3-methylacetophenone, 4-methylacetophenone, 4-allylacetophenone, 3-pentylacetophenone, and propiophenone.

[0040] Examples of α-hydroxyketones include 2-hydroxy-1-(4-isopropyl)phenyl-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methylpropan-1-one, and 1-hydroxycyclohexyl phenyl ketone.

[0041] Examples of the α-aminoketones include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, and the like.

[0042] Examples of α-diketones include benzyl and diacetyl.

[0043] Examples of the α-diketone dialkyl acetals include benzyl dimethyl acetal and benzyl diethyl acetal.

[0044] Examples of anthraquinones include 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, and 2-aminoanthraquinone.

[0045] Examples of thioxanthones include 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, and 2,4-diethylthioxanthone.

[0046] Examples of other compounds include tertiary amines such as triphenylamine and p-dimethylaminobenzoic acid ester, and azo compounds such as azobisisobutyronitrile.

[0047] When these photosensitizers are used, they may be used alone or in combination of two or more. The content thereof is preferably 0.01 to 30 parts by mass, and more preferably 0.05 to 20 parts by mass, per 100 parts by mass of the total amount of components (a) and (b).

[0048] In this embodiment, it is not necessary to actively add a solvent during coating; a solventless silicone release agent can be used. For example, in conventional methods such as actively adding a solvent to a coating liquid or using a solvent-based silicone release agent that already contains a certain amount of solvent, the solvent content in the coating liquid is high, unlike in this embodiment. In this regard, in this embodiment, the solvent content in the coating liquid is low, but sufficient releasability and adhesion to the substrate can be imparted. For example, when a coating liquid containing a solventless silicone release agent is heated from room temperature to 170°C at a heating rate of 10°C / min, the weight loss rate at 150°C is preferably 8.0% by mass or less, more preferably 6.0% by mass or less, even more preferably 5.0% by mass or less, and even more preferably 0% by mass. Note that the content loss rate is preferably 0% by mass, but the lower limit may be, for example, greater than 0% by mass, as long as the effect of this embodiment is obtained.

[0049] The weight loss rate of the coating liquid can be calculated by applying the weight at 150°C ("weight at 150°C") and the weight before heating ("weight before heating") to the following formula when the temperature is raised from room temperature to 170°C at a heating rate of 10°C / min. Specifically, the weight loss rate can be calculated in accordance with the method described in the examples. Weight loss rate (%) = (weight before heating - weight at 150°C) / weight before heating × 100

[0050] The coating liquid of this embodiment can be prepared by mixing the above-mentioned metal catalyst, photosensitizer, etc. with the above-mentioned solventless silicone release agent. For example, when using a coating liquid containing the above-mentioned catalyst (platinum-based catalyst, etc.), the coating liquid can be prepared by a process of obtaining the coating liquid by mixing the solventless silicone release agent with the metal catalyst without adding a solvent. The same applies when a photosensitizer, etc. is added. The solvent referred to here includes organic solvents, and specific examples thereof include aromatic solvents (benzene, toluene, xylene, etc.), hydrocarbon solvents (hexane, heptane, etc.), alcohol solvents (methanol, ethanol, propanol, butanol, cellosolves, propylene glycol monomethyl ethers, etc.), ester solvents (ethyl acetate, γ-butyl lactone, etc.), ketone solvents (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ether solvents (tetrahydrofuran, etc.), nitrogen atom-containing solvents (dimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc.), sulfur atom-containing solvents (dimethyl sulfoxide, etc.), etc.

[0051] In this embodiment, the coating liquid containing the above-mentioned components is applied to one or both sides of a PET substrate by any coating method, including, but not limited to, gravure coating, bar coating, spray coating, and spin coating.

[0052] The amount of coating liquid applied is 0.03 to 0.5 g / m 2 It is preferable that the density is 0.05 to 0.4 g / m 2 More preferably, it is 0.08 to 0.3 g / m 2 By setting the coating amount within this range, the thickness of the release layer can be thinned to a practical level, sufficient releasability can be imparted to the release layer, and sufficient adhesion to the PET-based substrate can be ensured.

[0053] In this manner, a laminate including a coating layer formed by applying a coating liquid onto a PET-based substrate can be obtained.

[0054] <Pre-irradiation process> Next, (2) the coating layer of the laminate is exposed to an integrated light dose of 8 to 1400 mJ / m 2 A pre-irradiation step is performed in which ultraviolet light is irradiated so that the surface becomes uniform. By performing this pre-irradiation before the heating step, only the outermost surface of the PET substrate is heated, which is expected to increase the flow of the release agent and provide an anchoring effect to the substrate (however, the effects of this embodiment are not limited to these).

[0055] The ultraviolet irradiation may be carried out in-line. Conventional ultraviolet lamps, such as high-pressure mercury lamps, metal halide lamps, high-power metal halide lamps, and electrodeless ultraviolet lamps, can be used as the ultraviolet lamp. Electrodeless ultraviolet lamps include D bulbs, H bulbs, H+ bulbs, and V bulbs manufactured by Fusion, with H bulbs and H+ bulbs being preferred.

[0056] The cumulative amount of UV light is 8 to 1400 mJ / m 2 and this upper limit is 1000mJ / m 2 Preferably, it is 700 mJ / m or less. 2 More preferably, it is 600 mJ / m or less. 2 It is more preferable that the lower limit is 9 mJ / m or less. 2 It is preferable that the concentration is 10 mJ / m or more. 2 More preferably, it is 15 mJ / m or more. 2 It is more preferable that the content is equal to or greater than this range. By setting the content within this range, it is possible to achieve a higher level of compatibility between the coating film formation, the releasability of the release layer, and the adhesion to the substrate. By setting the content at or greater than the above lower limit, the adhesion to the substrate is particularly improved, and by setting the content at or less than the above lower limit, damage to the substrate can be more effectively reduced and the occurrence of shrinkage and wrinkles can be more effectively prevented.

[0057] The irradiance of ultraviolet light is not particularly limited, but the upper limit is 500 mW / m 2 It is preferable that the power is less than 300mW / m2 More preferably, it is less than 250 mW / m 2 It is more preferable that the lower limit is 80 mW / m or less. 2 It is preferable that the power is 100mW / m or more. 2 More preferably, it is 120 mW / m or more. 2 More preferably, it is 150 mW / m or more. 2 More preferably, it is 170 mW / m or more. 2 It is even more preferable that the above is true.

[0058] <Heating process> (3) After the above step (2), the laminate is heated to react and cure the coating layer, thereby forming a release layer.

[0059] The heating temperature in step (3) is not particularly limited, but is preferably 50°C or higher and 200°C or lower. The upper limit is more preferably 170°C or lower, and even more preferably 150°C or lower. The lower limit is more preferably 70°C or higher, and even more preferably 80°C or higher. By setting the heating temperature within this range, it is possible to achieve a higher level of compatibility between coating film formation, releasability of the release layer, and adhesion to the substrate.

[0060] The heating time is not particularly limited, but the upper limit is preferably 60 seconds or less, more preferably 40 seconds or less. The lower limit is preferably 15 seconds or more, more preferably 20 seconds or more. By setting the heating time within this range, it is possible to achieve a higher level of compatibility between the coating film formation, the releasability of the release layer, and the adhesion to the substrate.

[0061] The heating method is not particularly limited, but heating methods using a dryer, oven, infrared furnace, etc. can be used.

[0062] (Post-irradiation process) In this embodiment, if necessary, post-irradiation with ultraviolet light may be performed after the heating step. That is, step (3) may be performed after step (2) above, by heating the laminate and then further irradiating it with ultraviolet light to reactively cure the coating layer and form a release layer.

[0063] The post-irradiation of ultraviolet light can be performed within the range of conditions described for the pre-irradiation step, and the post-irradiation conditions may be the same as or different from the pre-irradiation conditions.

[0064] In addition, the total integrated light amount of ultraviolet irradiation in this embodiment (the total of the pre-irradiation process and the post-irradiation process) is 8 to 1400 mJ / m 2 The upper limit of the total integrated light amount is preferably 1000 mJ / m 2 Preferably, it is 700 mJ / m or less. 2 More preferably, it is 600 mJ / m or less. 2 It is more preferable that the total amount of light is 9 mJ / m or less. 2 It is preferable that the concentration is 10 mJ / m or more. 2 More preferably, it is 15 mJ / m or more. 2 It is more preferable that the content is equal to or greater than this range. By setting the content within this range, it is possible to achieve a higher level of compatibility between the coating film formation, the releasability of the release layer, and the adhesion to the substrate. By setting the content at or greater than the above lower limit, the adhesion to the substrate is particularly improved, and by setting the content at or less than the above lower limit, damage to the substrate can be more effectively reduced and the occurrence of shrinkage and wrinkles can be more effectively prevented.

[0065] Next, a preferred embodiment of the release film obtained by the production method according to this embodiment will be described.

[0066] The thickness of the release layer of the release film is not particularly limited, but can be as thin as 0.03 to 0.6 μm. The upper limit of this thickness is more preferably 0.5 μm or less, and even more preferably 0.3 μm or less. The lower limit of this thickness is more preferably 0.04 μm or more, and even more preferably 0.06 μm or more.

[0067] Furthermore, the release strength of the release film is comparable to that of release films obtained by conventional manufacturing methods, and a practical level of release strength can be maintained. According to this embodiment, the release strength can be appropriately controlled depending on the application and field, and, to give one example, it is 10 to 1000 mN / 25 mm, and preferably 20 to 800 mN / 25 mm. The upper limit is more preferably 600 mN / 25 mm or less, and even more preferably 500 mN / 25 mm or less. The lower limit is more preferably 20 mN / 25 mm or more, and even more preferably 25 mN / 25 mm or more.

[0068] As described above, the release film obtained by the production method according to this embodiment has excellent releasability and adhesion to the substrate, and therefore can effectively prevent the release layer from peeling off the PET-based substrate even when stored or left stationary for a long period of time. Furthermore, even when the release layer is left stationary for several days (1 to 10 days or more) or when it is rubbed, the release agent can be effectively prevented from falling off the release film. Release films with such properties can be suitably used as adhesive protective materials for adhesive sheets used in optical devices such as displays, adhesive sheets for semiconductor processing, and the like. Furthermore, the production method according to this embodiment is expected to reduce the amount of solvent used, or even eliminate the need for solvent, and is therefore expected to be an environmentally friendly production method. [Example]

[0069] The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples. Note that percentages and parts are by weight unless otherwise specified.

[0070] In this example, the following materials were used:

[0071] (Removal agent) Dow-Toray Industries, Inc., product name "DOWSIL(TM) LTC1057L": Addition reaction type solventless silicone release agent (a solventless addition reaction type silicone containing polyorganosiloxane with alkenyl groups in the molecule and a polyorganosiloxane crosslinker with hydrosilyl groups in the molecule) Shin-Etsu Chemical Co., Ltd., product name "KNS 3056": Addition reaction type solventless silicone release agent (a solventless addition reaction type silicone containing polyorganosiloxane with vinyl groups in the molecule and a polyorganosiloxane crosslinker with hydrosilyl groups in the molecule) (catalyst) Dow Toray Industries, Inc., product name "DOWSIL(TM) SRX-212 Catalyst": platinum catalyst Shin-Etsu Chemical Co., Ltd., product name "CAT-PL-56": platinum catalyst

[0072] Example 1

[0073] First, a polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Corporation, trade name "Diafoil T-100"; thickness 38 μm) was prepared as a substrate. Then, 100 parts by mass of an addition reaction type solventless silicone release agent (manufactured by Dow-Toray Industries, Inc., trade name "DOWSIL™ LTC1057L") and a platinum catalyst (manufactured by Dow-Toray Industries, Inc., trade name "DOWSIL™ SRX-212 Catalyst") were mixed without adding a solvent to prepare a solventless coating fluid (weight loss rate of coating fluid at 150°C: 2.1% by mass; see "Weight loss rate at 150°C (%)" in Table 1).

[0074] The "weight loss rate" was determined according to the following method. First, 20 mg of the coating liquid was prepared as a sample. Then, using a TG-DTA (Shimadzu Corporation, differential thermal and thermogravimetric simultaneous analyzer "DTG-60"), the sample was heated from room temperature to 170°C at a heating rate of 10°C / min. The weight at 150°C ("weight at 150°C") and the weight before heating ("weight before heating") were determined. These values ​​were then applied to the following formula to determine the weight loss rate (%). Weight loss rate (%) = (weight before heating - weight at 150°C) / weight before heating × 100

[0075] Then, using a coating device (manufactured by Kumagai Riki Kogyo Co., Ltd., device name "RI Tester"), the above coating liquid was applied to the substrate in a coating amount of 0.25 g / m 2 The mixture was applied to one surface of the substrate so as to form a coating layer (coating film). Next, while the coating layer was still wet (uncured), ultraviolet light (UV) was irradiated from the coated surface (integrated light intensity 100 mJ / m 2 , illuminance 200mW / m 2 (See "UV irradiation before thermal curing" in Table 1). Then, the film was placed in an oven and cured at 100°C for 30 seconds. Through these treatments, the coating layer was cured to form a release layer, and a release film was obtained.

[0076] <Examples 2 to 10>

[0077] A release film was obtained in the same manner as in Example 1, except that the conditions were changed as shown in Table 1. In Example 6, after the film was removed from the oven, ultraviolet light (UV) was further irradiated from the coated surface (cumulative light dose 100 mJ / m 2 , illuminance 200mW / m 2 The weight loss rates at 150°C of the solvent-free coating solutions prepared in Examples 2 to 10 were as shown in Table 1 under "Weight loss rate at 150°C (%)."

[0078] <Comparative Examples 1 to 5>

[0079] Release films were obtained in accordance with the same procedures as in Example 1, except for the changes in conditions shown in Table 1. In Comparative Examples 1 and 2, UV irradiation was not performed, and in Comparative Example 3, UV irradiation was not performed before heating (pre-irradiation), but was performed after heating (post-irradiation).

[0080] <Evaluation method>

[0081] The physical properties of each of the resulting release films were evaluated according to the methods described below.

[0082] (Evaluation of peeling properties and peeling force) An acrylic adhesive (manufactured by Toyochem Co., Ltd., product name "Olivine (registered trademark) BPS-5127") was applied to the release surface of the release film prepared in each Example and Comparative Example using an applicator, and dried at 100°C for 2 minutes to form an adhesive layer with a thickness of 125 μm. Furthermore, a PET film (manufactured by Toray Industries, Inc., product name "Lumirror (registered trademark) T-60", thickness: 50 μm) was attached to the surface of the adhesive layer opposite the release film to obtain an adhesive sheet as a measurement sample. This measurement sample was fixed to a universal tensile testing machine (Shimadzu Corporation, product name "Autograph AGS-20NX"), and the force when the release film was peeled in the 180° direction at a pulling rate of 0.3 m / min was measured in accordance with JIS K6854:1999, and this was taken as the peel force (mN / 25 mm).

[0083] (exterior) The appearance of the prepared release film was visually observed under a fluorescent lamp, and the evaluation criteria were as follows: ◯: There are no strong wrinkles and the film is not distorted. ×: Strong wrinkles were observed and the film was distorted.

[0084] (Rub-off test) The adhesion of the release layer of the release film was evaluated. Specifically, immediately after processing (immediately after preparation), 1 day later, 3 days later, and 10 days later, the surface of the release layer was rubbed with a finger five times in the X direction (a predetermined direction), and then rubbed with a finger five times in the Y direction perpendicular to the X direction. The smear (cloudiness) and rub-off (fall-off) at the intersection of the X direction and the Y direction were visually confirmed. The evaluation criteria were as follows. "◯": Neither clouding nor falling off was observed. "△": Cloudiness was observed. "X": Dropout was confirmed.

[0085] Table 1 shows the production conditions for each example and comparative example, and Table 2 shows the evaluation results.

[0086] [Table 1]

[0087] [Table 2]

[0088] From the above, it was confirmed that this example can at least provide release properties that are practical for use as a release film and can produce a release film that has excellent adhesion to the substrate. Furthermore, since it was confirmed that the production method of this example can provide sufficient physical properties using a solventless silicone release agent as the release agent without using a solvent, it is also expected to be an environmentally friendly production method.

Claims

1. (1) applying a coating solution containing an addition reaction type solventless silicone release agent to a polyethylene terephthalate substrate to obtain a laminate including a coating layer; (2) The coating layer of the laminate is exposed to an integrated light amount of 8 to 500 mJ / m ２ a pre-irradiation step of irradiating ultraviolet light so that the (3) after the step (2), heating the laminate to reactively cure the coating layer and form a release layer; A method for producing a release film, comprising:

2. The step (3) is a step of, after the step (2), heating the laminate and then further irradiating it with ultraviolet light to reactively cure the coating layer and form a release layer. A method for producing the release film according to claim 1.

3. the coating liquid containing the solventless silicone release agent has a weight loss rate of 8.0% by mass or less at 150°C when heated from room temperature to 170°C at a heating rate of 10°C / min; A method for producing the release film according to claim 1 or 2.

Images