TWI862535B - Ablative silicone resin composition and release film coated with the composition - Google Patents

Abstract

The present application provides an ablative silicone resin composition and a release film coated with the composition, the composition including: polyorganosiloxane (A) having a vinyl group bonded with a silicon atom located at a portion other than end portions and whose average molecular weight ranges from 30 to 1,000,000; polyorganosiloxane (B) having vinyl groups at two ends thereof and whose average molecular weight ranges from 1 to 100,000; polyorganohydrogensiloxane (C) having hydrogen atom directly bonded with a silicon atom located at a portion other than end portions; a curing activator (D); hydrolytic binary silicon-hydrogen compounds (E) containing a reactivity functional group; and an aluminum chelation.

Description

Releasable silicone resin composition and release film coated with the composition

The present invention relates to a peelable silicone resin composition having good adhesion to an adhesion-treated film or an untreated polyester film that has not been subjected to an adhesion-treated film. Specifically, when the composition is applied to the adhesion layer of an adhesion-treated film or an untreated polyester film that has not been subjected to an adhesion-treated film to form a release film having a silicone layer, the silicone layer side of the release film is adhered to glass and each release film is peeled off after a long period of time. The peelable silicone resin composition and the release film coated with the composition have little increase in adhesion over time and are less likely to leave so-called adhesive residues on the glass surface.

In the prior art, regarding a fixing sheet that can be easily reattached and can be removed with a slight peeling force without generating adhesive residues, an inventor disclosed a fixing sheet in which an easy-adhesive layer and a silicone resin layer are laminated on at least one surface of a substrate, wherein the easy-adhesive layer is composed of a polyester resin having a hydroxyl value of 10 to 45 or an acrylic resin having a hydroxyl value of 10 to 45, and a silicone selected from a linear polyorganosiloxane having vinyl groups only at both ends, a silicone having vinyl groups at both ends and side chains, and a silicone resin having a vinyl group at both ends and side chains. At least one of silicone composed of straight-chain polyorganosiloxane having vinyl groups, silicone composed of branched-chain polyorganosiloxane having vinyl groups only at the ends, and silicone composed of branched-chain polyorganosiloxane having vinyl groups at the ends and side chains is cross-linked with organohydrogenpolysiloxane to form a silicone resin layer, and a fixing sheet containing silicone oil is contained in the silicone resin layer (as shown in Japanese Patent Document 1).

However, when the fixing plate is adhered to the glass, the silicone oil migrates to the interface of the glass, and since the reaction between the SiH group that does not contribute to the addition reaction of silicon and the OH group on the glass surface is suppressed to prevent the residual adhesive when the fixing plate is peeled off again, when the fixing plate is peeled off again, the unreacted organic hydropolysiloxane and silicone oil may remain on the glass surface, sometimes contaminating the glass surface.

In addition, in the fixing sheet, the polyester resin or acrylic resin forming the easy-adhesive layer has a hydroxyl value as high as 10 to 45, and the polyester resin or acrylic resin having a hydroxyl value less than 10 has a problem of being difficult to use to form the easy-adhesive layer because the adhesion between the easy-adhesive layer formed thereby and the silicone resin layer is weak. If such polyester resin or acrylic resin is used to form an easy-adhesive layer on a substrate, the silicone resin layer described in the above-mentioned patent document 1 will not be applicable.

On the other hand, as a releasable silicone resin composition and a release film coated with the composition that solves these problems, an inventor discloses a releasable silicone resin composition coated on an easy-adhesion layer of an easy-adhesion treatment film formed by coating a polyester resin having a hydroxyl value of 3 to 45 mgKOH/g on at least one surface of a base film, and comprising a polyester resin having vinyl groups at both ends, A linear or branched polyorganosiloxane (A) having a weight average molecular weight of 30 to 1,000,000; a linear or branched polyorganosiloxane (B) having vinyl groups at both ends and a weight average molecular weight of 1 to 1,000,000; a polyorganosiloxane having an OH group content of less than 1% by weight and having a general formula of SiO A silicone resin (C) composed of _{SiO 1/2} units and SiO _4/2 units, wherein the molar ratio of SiO _1/2 units/SiO _4/2 units is 0.5:1.0 to 0.8:1.0; a polyorganohydrogensiloxane (D) having a viscosity of 10 to 100 cSt/25°C and having hydrogen atoms directly bonded to silicon atoms on the side chains; a curing catalyst (E) required for addition reaction; a hydrolyzable silane compound containing a reactive functional group (F); and an aluminum chelate (G), and a release film coated with the composition to form a silicone resin layer (as shown in Japanese Patent Document 2).

[Patent Literature]

[Patent document 1] Japanese Patent No. 4505649

[Patent Document 2] Japanese Patent Publication No. 2016-98286

However, the releasable silicone resin composition and the release film coated with the composition described in Patent Document 2 have good adhesion to a thin film of an easy-adhesion layer having a hydroxyl value of less than 10 mg, but have a problem that the adhesion to an untreated polyester film that has not been subjected to an easy-adhesion treatment becomes insufficient over time. In addition, there is a problem that the absolute value of the peel strength of the adhesion to glass becomes larger over time and becomes difficult to peel. Furthermore, especially from the perspective of these two issues, it can be found that the release silicone resin composition and the release film coated with the composition described in Patent Document 2 are difficult to say that the untreated polyester film that has not been treated to improve adhesion is a release silicone resin composition and a release film coated with the composition that have sufficient release and adhesion properties.

On the other hand, the present invention provides a releasable silicone resin composition having good adhesion to the easy-adhesion layer formed on an easy-adhesion treatment film even if the hydroxyl value of the easy-adhesion layer is less than 10. At the same time, it is not easy to lose sufficient adhesion to an untreated polyester film that has not been subjected to an easy-adhesion treatment over time, and the absolute value of the peel strength used to represent the adhesion to glass does not increase much over time, thereby having sufficient releasability for a long time. In addition, from these points of view, the present invention provides a release film coated with the release silicone composition of the present invention, which has sufficient release and adhesion properties even when the release silicone composition of the present invention is applied to a release film of an untreated polyester film that has not been subjected to an adhesion-promoting treatment. In addition, the release silicone composition is unlikely to leave residual rubber on the glass surface and is unlikely to contaminate the glass surface, and a release film coated with the release silicone composition.

One embodiment of the present invention provides a releasable silicone resin composition, which is applied to the easy-adhesion layer of an easy-adhesion treatment film formed by applying a polyester resin with a hydroxyl value of 3 to 45 mg KOH/g on at least one surface of a base film to form an easy-adhesion layer, or is used for application on a surface of a base film that is a polyester film and has no easy-adhesion layer formed thereon, and comprises: a linear or branched polyorganosiloxane (A) having a vinyl bond to a silicon atom other than a terminal and a weight average molecular weight of 300,000 to 1,000,000; a polyorganosiloxane (A) having a vinyl bond to a silicon atom other than a terminal and a weight average molecular weight of 10,000 to 100,000; Linear or branched polyorganosiloxane (B); polyorganohydrogensiloxane (C) having hydrogen atoms directly bonded to silicon atoms other than the terminal; a curing catalyst (D) required for the addition reaction; a hydrolyzable silane compound containing a reactive functional group (E); and an aluminum chelate (F), (A) The content of vinyl groups in the linear or branched polyorganosiloxane is 0.01% by weight or more and 5.0% by weight or less.

In addition, in one embodiment of the present invention, a releasable silicone resin composition is provided which further comprises a polyorganosiloxane (G) having an OH group content of 0.1 to 5.0 wt %, a general formula consisting of SiO _1/2 units and SiO _4/2 units, and a molar ratio of SiO _1/2 units to SiO _4/2 units of 0.5 to 1.0.

In addition, in one embodiment of the present invention, a releasable silicone resin composition is provided, wherein the hydrolyzable silane compound (E) containing a reactive functional group is 3-glycidoxypropyltrimethoxysilane.

In addition, in one embodiment of the present invention, a releasable silicone resin composition is provided, wherein the aluminum chelate (F) is triethyl acetylacetate aluminum.

In addition, in one embodiment of the present invention, a releasable silicone resin composition is provided, wherein the hydrolyzable silane compound (E) containing a reactive functional group is composed of 0.8 to 3.5 parts by weight relative to 100 parts by weight of the total amount of polyorganosiloxane (A), polyorganosiloxane (B) and polyorganohydrosiloxane (C).

In addition, in one embodiment of the present invention, a releasable silicone resin composition is provided, wherein the aluminum chelate (F) is contained in an amount of 0.08 to 0.35 parts by weight relative to 100 parts by weight of the total amount of polyorganosiloxane (A), polyorganosiloxane (B) and polyorganohydrosiloxane (C).

In addition, in one embodiment of the present invention, the above-mentioned release silicone resin composition is applied on the easy-adhesion layer of the easy-adhesion treatment film in which a polyester resin with a hydroxyl value of 3 to 45 mg KOH/g is applied on at least one surface of the base film to form an easy-adhesion layer to form a silicone layer, or the above-mentioned release silicone resin composition is applied on the surface of the base film which is a polyester film and has no easy-adhesion layer formed to form a release film.

The peelable silicone resin composition of one embodiment of the present invention has a good adhesive effect even if the easy-adhesion layer provided on at least one surface of the easy-adhesion treated film is formed of a polyester resin having a hydroxyl value of less than 10. In addition, the peelable silicone resin composition of one embodiment of the present invention has a sufficient adhesive effect to an untreated polyester film that has not been subjected to an easy-adhesion treatment and does not easily lose the sufficient adhesive effect over time, and because the absolute value of the peeling strength used to indicate the adhesiveness to glass does not increase much over time, the peeling effect is sufficient for a long time. In particular, due to such effects, even if a release film having a release silicone resin composition of one embodiment of the present invention is coated on an untreated polyester film that has not been treated for easy adhesion, it has sufficient release and adhesion effects.

In addition, the peelable silicone composition according to one embodiment of the present invention has the effect that even if the silicone layer side of the release film formed on the adhesive treatment film or the untreated polyester film with the silicone layer is adhered to the glass, and the release film is peeled off from the glass after a long time, it is not easy to leave any residue on the glass surface. In addition, the peelable silicone composition according to one embodiment of the present invention has the effect of not easily contaminating the glass surface because it does not use silicone oil that is easy to transfer.

In addition, in particular, the release film of one embodiment of the present invention has the effect of sufficient adhesion between the silicone resin layer and the base film and being difficult to peel off even if the easy-adhesive layer formed on the base film is formed of a polyester resin with a hydroxyl value of 10 mgKOH/g or less, or the base film is a polyester film and an untreated polyester film without an easy-adhesive layer formed thereon. In addition, if the silicone resin layer side is adhered to glass and the release film is peeled off from the glass after a long time, it has sufficient adhesion and peeling properties, and has the effect of being difficult to produce adhesive residues on the glass surface and having the effect of being difficult to contaminate the glass surface.

The following is a detailed description of the releasable silicone resin composition according to one embodiment of the present invention.

[Polyorganosiloxane (A)]

The polyorganosiloxane (A) used in one embodiment of the present invention is a linear or branched polyorganosiloxane with a weight average molecular weight of 300,000 to 1,000,000 and a vinyl group bonded to a silicon atom other than a terminal, and is used together with the polyorganosiloxane (B) shown below. In particular, the polyorganosiloxane (A) is used to exhibit viscoelastic adhesion to an easy-adhesion layer formed on an easy-adhesion treatment film or an untreated polyester film surface due to its large molecular weight. In addition, the polyorganosiloxane (A) is cured by an addition reaction of the polyorganohydrosiloxane (C) and a curing catalyst (D) shown below, and the organic groups bonded to the silicon atom other than the vinyl group may be of different types or the same type. Specifically, it includes methyl, ethyl, phenyl, etc. A specific example is vinyl bonding (part of the methyl groups bonded to the silicon atoms other than the terminal are replaced by vinyl groups) to part of the silicon atoms other than the terminal of polydimethylsiloxane. The weight average molecular weight of the polyorganosiloxane is preferably 300,000 to 1,000,000 as measured by GPC. If it is less than 300,000, the viscosity of the composition is too low. If it exceeds 1,000,000, the viscosity of the composition is high and each coating property becomes insufficient. The vinyl content is preferably 0.01% by weight or more. In addition, the vinyl content is preferably 5.0% by weight or less.

[Polyorganosiloxane (B)]

The polyorganosiloxane (B) used in one embodiment of the present invention is a linear or branched polyorganosiloxane having vinyl groups at both ends and a weight average molecular weight of 10,000 to 100,000, and is used together with the above-mentioned polyorganosiloxane (A). In particular, since the polyorganosiloxane (B) has a smaller molecular weight, it will be used to exhibit adhesion to the easy-adhesion layer formed on the easy-adhesion treatment film. In addition, the polyorganosiloxane (B) is cured by the addition reaction of the polyorganohydrogensiloxane (C) and the curing catalyst (D) shown below, similarly to the polyorganosiloxane (A), and the organic groups bonded to the silicon atoms other than the vinyl groups may be of different types or the same type. Specifically, they include methyl, ethyl, phenyl, etc. A specific example is polydimethylsiloxane with vinyl groups at both ends. The weight average molecular weight of the polyorganosiloxane is preferably 10,000 to 100,000 as measured by GPC. If it is less than 10,000, the crosslinking density becomes high and the adhesion to substrates such as glass becomes insufficient. If it exceeds 100,000, the viscosity of the composition becomes high and the coating property becomes insufficient.

[Polyorganohydrogensiloxane (C)]

The polyorganohydrogen siloxane (C) used in one embodiment of the present invention has hydrogen atoms directly bonded to silicon atoms other than the terminal, and preferably has a viscosity of 10 to 100 cSt/25°C. The polyorganohydrogen siloxane (C) is crosslinked and cured by an addition reaction of the polyorganosiloxane (A) with the polyorganosiloxane (B) and a curing catalyst (D). In order to exhibit adhesion, the silicon atoms directly bonded to the hydrogen atoms are preferably located outside the terminal. When hydrogen atoms bond to silicon atoms located at the terminal, the hardness of the cured product increases and the releasability becomes insufficient. In addition, if the viscosity is less than 10 cSt/25°C, the crosslinking density decreases and the curing property decreases, and if it exceeds 100 cSt/25°C, the crosslinking density increases and the adhesion to the base film decreases.

In addition, the content of hydrogen atoms bonded to silicon atoms is preferably 1.0 mmol/g to 20.0 mmol/g. If it is 1.0 mmol/g or more, the curing property becomes good. If the content of hydrogen atoms is greater than 20.0 mmol/g, the viscosity on the surface of the cured product becomes too strong. In order to obtain good adhesion to the polyester film, the hydrogen atom content is more preferably 1.5 mmol/g or more. Examples of organic groups bonded to silicon atoms include methyl, ethyl, phenyl, etc. The polyorganohydrogensiloxane can be, for example, linear or branched, and a specific example is methylphenyl hydrogen polysiloxane.

[Curing catalyst (D)]

The curing catalyst (D) used in one embodiment of the present invention is used to produce the addition reaction between the above-mentioned polyorganosiloxane (A) and polyorganosiloxane (B) and polyorganohydrosiloxane (C). Known metals, metal compounds, metal complexes, etc. that have catalytic activity for hydrosilylation can be used as the addition reaction. In particular, platinum, platinum compounds, and these complexes are preferably used. These catalysts can be used alone or in combination of two or more. In addition, a co-catalyst can be used in combination. The amount of the curing catalyst (D) relative to the entire composition is preferably 1 ppm to 50 ppm, and more preferably 5 to 20 ppm. If it is less than 1 ppm, the curability will be reduced, and if it is greater than 50 ppm, the transparency of the cured product will be reduced.

[Hydrolyzable silane compound containing reactive functional groups (E)]

The hydrolyzable silane compound (E) containing a reactive functional group used in one embodiment of the present invention is used to improve the adhesion over time to the easy adhesion layer formed on the easy adhesion treatment film or the untreated polyester film. For example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, etc. can be used. The amount of the hydrolyzable silane compound (E) containing a reactive functional group is preferably 0.8 to 3.5 parts by weight relative to 100 parts by weight of the total amount of polyorganosiloxane (A), polyorganosiloxane (B) and polyorganohydrosiloxane (C). If it is less than 0.8 parts by weight, the adhesion becomes insufficient over time. If it exceeds 3.5 parts by weight, the adhesion to the glass will increase over time and the peeling property will deteriorate.

〔Aluminum chelate (F)〕

The aluminum chelate (F) used in one embodiment of the present invention is used as a condensation catalyst for the hydrolyzable group of the above-mentioned hydrolyzable silane compound containing a reactive functional group, and is used to suppress the increase in adhesion to glass and the decrease in releasability over time. Specifically, ethyl acetoacetate aluminum diisopropylate, ethyl acetoacetate aluminum dibutyrate, diethyl acetoacetate aluminum butyrate, tris(ethylacetoacetate)aluminum, alkyl acetoacetate aluminum diisopropylate, etc. can be mentioned, and they can be used alone or as a mixture of two or more. The amount of the aluminum chelate (F) is preferably 0.08 to 3.5 parts by weight relative to the total amount of polyorganosiloxane (A), polyorganosiloxane (B) and polyorganohydrosiloxane (C) of 100 parts by weight. If it is less than 0.08 parts by weight, the adhesion becomes insufficient over time. If it exceeds 0.35 parts by weight, the adhesion to the glass will increase over time and the releasability will decrease.

[Polysilicone (G)]

The polyorganosiloxane (G) used in one embodiment of the present invention has an OH group content of 0.1 to 5.0 wt % and a general formula consisting of SiO _1/2 units and SiO _4/2 units, and the molar ratio of SiO _1/2 units/SiO _4/2 units is 0.5 to 1.0. It can be used as a tackifier to improve the initial adhesion of the glass of the exfoliative silicone resin composition of one embodiment of the present invention, and can be mixed to inhibit the increase of adhesion to the glass over time. If the OH content exceeds 5.0 wt %, the curability of the composition will be reduced. If the molar ratio of SiO _1/2 units/SiO _4/2 units is less than 0.5 and greater than 1.0, the improvement of adhesion strength may not be good enough.

The present composition may contain, as other optional components, alkynols such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and ethynylcyclohexanol, enyne compounds such as 3-methyl-3-pentene-1-yne and 3,5-dimethyl-3-hexene-1-yne, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetrahexylcyclotetrasiloxane, 1,3 divinyltetramethyldisiloxane, and reaction inhibitors such as benzotriazole. The reaction inhibitor is preferably contained in an amount that does not inhibit curing due to the addition reaction, preferably in the range of 0.0001 to 1 part by weight relative to 100 parts by weight of the total amount of polyorganosiloxane (A), polyorganosiloxane (B) and polyorganohydrosiloxane (C).

In addition, within the scope of not impairing the purpose of the present invention, other arbitrary components may include inorganic fillers for adjusting viscosity and hardness, such as calcium carbonate, silica sand, talc, carbon black, titanium oxide, zinc oxide, kaolin, silicon dioxide, melamine, etc., and reinforcing materials such as glass fiber for reinforcing organic fillers and curing resins, as well as hollow bodies for weight reduction and viscosity adjustment, such as white sand balloons and glass balloons. Others, antioxidants, organic pigments, fluorescent pigments, preservatives, antioxidants, etc. may be used appropriately.

The release film of one embodiment of the present invention is a release film formed by coating a polyester resin having a hydroxyl value of 3 to 45 mgKOH/g on at least one surface of a base film such as a polyester film to form an easy-adhesion layer as an easy-adhesion treated film, and then coating the above-mentioned release silicone resin composition on the easy-adhesion layer to form a release film of a silicone resin layer, or the base film is a polyester film, and the above-mentioned release silicone resin composition is similarly coated on an untreated surface without an easy-adhesion layer to form a release film of a silicone resin layer.

The thickness of the easy-adhesive layer of the easy-adhesive treatment film is preferably in the range of 0.05 to 5.0 μm. If the thickness is less than 0.05 μm, sufficient adhesion effect cannot be achieved, and if the thickness exceeds 5.0 μm, the adhesion to the base film of the easy-adhesive layer itself will be reduced. The coating method of the easy-adhesive layer coating liquid and the silicone resin layer coating liquid can appropriately use a multi-roll coater represented by a three-roll gravure coater (offset gravure coater) or a five-roll coater, a direct slot roll coater, a rod coater, an air knife coater, etc. If the hydroxyl value of the polyester resin in the easy-adhesion layer is less than 3 mgKOH/g, the easy-adhesion treated film cannot be said to have been subjected to the easy-adhesion treatment, and even if the polyester resin is applied, the film is included in the definition of an untreated polyester film. In addition, if the hydroxyl value of the polyester resin in the easy-adhesion layer exceeds 45 mgKOH/g, the curability of this composition will deteriorate. The hydroxyl value is an indicator of the polarity of the easy-adhesion layer. The higher the hydroxyl group, the higher the polarity, and the higher the adhesion between this composition and the easy-adhesion layer.

After forming the silicone layer, a separator such as a resin film or coating paper may be further attached to the surface of the silicone layer to suppress the adhesion of dirt or foreign matter to the surface of the silicone layer and improve the operability of the release film.

[Implementation example]

Next, the exfoliative silicone resin composition of one embodiment of the present invention will be described in detail through examples and comparative examples.

《Implementation Examples and Comparative Examples》

As polyorganosiloxane (A), a linear polydimethylsiloxane having a weight average molecular weight of 30 to 1,000,000 and vinyl groups bonded to a part of the silicon atoms other than the terminals (vinyl content: 0.07% by weight); as polyorganosiloxane (a), a linear polydimethylsiloxane having a weight average molecular weight of 30 to 1,000,000 and vinyl groups at both terminals (vinyl content: 0.01% by weight); as polyorganosiloxane (b), a linear polydimethylsiloxane having a weight average molecular weight of 1 to 100,000 and vinyl groups bonded to a part of the silicon atoms other than the terminals (vinyl content: 0.07% by weight); as polyorganosiloxane (c), a linear polydimethylsiloxane having a weight average molecular weight of 1 to 100,000 and vinyl groups bonded to a part of the silicon atoms other than the terminals (vinyl content: 0.01% by weight); as polyorganosiloxane (d), a linear polydimethylsiloxane having a weight average molecular weight of 1 to 100,000 and vinyl groups bonded to a part of the silicon atoms other than the terminals (vinyl content: 0.07% by weight); as polyorganosiloxane (e), a linear polydimethylsiloxane having a weight average molecular weight of 30 to 1,000,000 and vinyl groups at both terminals (vinyl content: 0.01% by weight); as polyorganosiloxane (f), a linear polydimethylsiloxane having a weight average molecular weight of 1 to 100,000 and vinyl groups bonded to a part of the silicon atoms other than the terminals (vinyl content: 0.07% by weight); as polyorganosiloxane (g), a linear polydimethylsiloxane having a weight average molecular weight of 1 to 100,000 and vinyl groups bonded to a part of the silicon atoms other than the terminals (vinyl content: 0. organosiloxane (B); polyorganohydrosiloxane (C) having a viscosity of 10 to 100 cSt/25°C and having hydrogen atoms directly bonded to silicon atoms other than the terminal (hydrogen atom content: 14 mmol/g); platinum-vinyl dimer complex (Pt: 0.2%wt) as a curing catalyst (D); 3-glycidoxypropyltrimethoxysilane as a hydrolyzable silane compound containing a reactive functional group (E); aluminum triethylacetoacetate as an aluminum chelate (F); an OH group content of 1% by weight, and composed of SiO _1/2 unit/SiO _4/2 unit, SiO _1/2 unit/SiO MQ resin with a molar ratio of 0.7 in _4/2 units as polyorganosiloxane (G), toluene as solvent, and ethynyl cyclohexanol as reaction inhibitor were fully mixed according to the dosage shown in Table 1 to obtain a uniform solution as the coating liquid of the stripping silicone resin composition of the embodiment and the comparative example. Next, a polyester resin with a hydroxyl value of 5 mgKOH/g was coated on a single surface and cured. The coating liquid is applied on the easy-adhesive layer of an easy-adhesive treated film made of polyester having an easy-adhesive layer and a thickness of 75 μm, or on the untreated surface of an untreated polyester film having a thickness of 75 μm without forming an easy-adhesive layer so that the thickness after drying is 20 μm and the film is cured at 130° C. for 90 seconds to form a silicone layer; a release film coated with the releasable silicone resin composition of the embodiment and the comparative example is obtained.

[Evaluation items and evaluation methods] <Initial Adhesion>

Each release film of the embodiment and comparative example was formed into a 2.5cm×15cm strip, and the silicone layer of the release film was brought into close contact with the surface of a 5cm×20cm (thickness 0.25cm) soda glass. A 2kg hand roller specified by JIS Z0237 was moved back and forth on the release film and pressed the silicone layer. After pressing, the 180-degree peel strength (mN/25mm) was measured at 23°C according to JIS Z0237. If the peel strength is 5mN/25mm or more, it is judged to have sufficient adhesion. In this evaluation, 10mN/25mm or more and 50mN/25mm or less are evaluated as ○, and the others are evaluated as ×.

<Adhesion after heating>

Each release film of the embodiment and comparative example was formed into a 2.5cm×15cm strip, and the silicone resin layer of the release film was closely contacted with the surface of a 5cm×20cm (thickness 0.25cm) soda glass. A 2kg hand roller specified by JISZ0237 was moved back and forth on the release film and pressed the silicone resin layer. After 14 days of maintenance at 60°C and 90%RH, the 180-degree peel strength (mN/25mm) was measured at 23°C according to JIS Z0237. The peel strength of 20mN/25mm or more and 150mN/25mm or less was evaluated as ○, and the others were evaluated as ×.

<Initial adhesion to a polyester film with an easy-adhesive layer or without an easy-adhesive layer>

Each release film of the examples and comparative examples was formed into a strip of 2.5 cm × 15 cm, and the silicone layer of the release film was brought into close contact with the surface of a 5 cm × 20 cm (thickness 0.25 cm) soda glass, and a 2 kg hand roller specified in JIS Z0237 was moved back and forth once on the release film and pressed the silicone layer. Thereafter, the release film was slowly peeled off, and the silicone layer of the release film was rubbed with fingertips at 23°C. At this time, those where the silicone resin layer was completely peeled off from the easy-adhesion layer were evaluated as x, those where the silicone resin layer was partially peeled off were evaluated as Δ, and those where the silicone resin layer was not peeled off were evaluated as ○.

<Adhesion after heating to a polyester film with an easy-adhesive layer or one without an easy-adhesive layer>

Each release film of the embodiment and comparative example was formed into a strip of 2.5 cm × 15 cm, and the silicone layer of the release film was brought into close contact with the surface of a 5 cm × 20 cm (thickness 0.25 cm) soda glass. A 2 kg hand roller specified in JIS Z0237 was moved back and forth on the release film once and pressed the silicone layer. After that, after 21 days of maintenance at 60°C and 90% RH, it was gradually cooled to 23°C, and the release film was slowly peeled off, and the silicone layer of the release film was rubbed with fingertips. At this time, those where the silicone layer was completely peeled off from the easy-adhesive layer were evaluated as x, those where it was partially peeled off were evaluated as Δ, and those where it was not peeled off were evaluated as ○.

<Residual Rubber>

Each release film of the embodiment and comparative example was formed into a 2.5cm×15cm strip, and the silicone layer of the release film was brought into close contact with the surface of a 5cm×20cm (thickness 0.25cm) soda glass. A 2kg hand roller specified by JISZ0237 was moved back and forth on the release film and pressed the silicone layer. After that, after 21 days of maintenance at 60°C and 90%RH, it was gradually cooled to 23°C, and the release film was slowly peeled off to visually and with fingers to observe the state of the glass surface. Those without fogging or stickiness on the glass surface were evaluated as ○, and those with fogging or stickiness were evaluated as x.

<Evaluation results>

The evaluation results are shown in Table 2.

Claims (7)

A release silicone resin composition is used for coating on the easy-adhesion layer of an easy-adhesion treatment film formed by coating a polyester resin with a hydroxyl value of 3 to 45 mg KOH/g on at least one surface of a base film to form the easy-adhesion layer, or for coating on the surface of a base film of a polyester film on which the easy-adhesion layer is not formed. The release silicone resin composition comprises: (A) a linear or branched polyorganosiloxane, in which a vinyl group is bonded to a silicon atom other than a terminal and the weight average molecular weight is 300,000 to 1,000,000; (B) a linear or branched polyorganosiloxane (C) polyorganohydrosiloxane having vinyl groups at both ends and a weight average molecular weight of 10,000 to 100,000; (D) a curing catalyst required for the addition reaction; (E) a hydrolyzable silane compound containing a reactive functional group; and (F) an aluminum chelate, wherein the content of vinyl groups in the linear or branched polyorganosiloxane (A) is greater than 0.01% by weight and less than 5.0% by weight. The exfoliative silicone resin composition as described in claim 1 further comprises: (G) polyorganosiloxane, wherein the OH group content is 0.1 to 5.0 wt %, and the general formula is composed of SiO _1/2 units and SiO _4/2 units, and the molar ratio of SiO _1/2 units/SiO _4/2 units is 0.5 to 1.0. The stripping silicone resin composition as described in claim 1, wherein the hydrolyzable silane compound (E) containing a reactive functional group is 3-glycidoxypropyltrimethoxysilane. The exfoliative silicone resin composition as described in claim 1, wherein the aluminum chelate (F) is triethyl acetylacetate aluminum. The exfoliative silicone resin composition as described in claim 1, wherein the hydrolyzable silane compound (F) containing a reactive functional group is 0.8 to 3.5 parts by weight relative to 100 parts by weight of the total amount of the polyorganosiloxane (A), the polyorganosiloxane (B) and the polyorganohydrosiloxane (C). The exfoliative silicone resin composition as described in claim 1, wherein the aluminum chelate (F) is contained in an amount of 0.08 to 0.35 parts by weight relative to 100 parts by weight of the total amount of the polyorganosiloxane (A), the polyorganosiloxane (B) and the polyorganohydrosiloxane (C). A release film, wherein the release film is structured such that a release silicone resin composition as described in any one of claims 1 to 6 is applied on an easy-adhesion layer of an easy-adhesion treatment film in which a polyester resin having a hydroxyl value of 3 to 45 mg KOH/g is applied on at least one surface of a base film to form an easy-adhesion layer to form a silicone layer, or a release silicone resin composition as described in any one of claims 1 to 6 is applied on a surface of a base film which is a polyester film and on which an easy-adhesion layer is not formed to form a silicone layer.