JP2020200418A - Heat resistant protective adhesive film - Google Patents

Abstract

To provide a heat resistant protective adhesive film, which can be peeled from an adherend without an adhesive residue even after undergone a high temperature environment, can suppress transfer of an oligomer derived from a polyethylene terephthalate base material on a surface of an adhesive layer, and has flexibility.SOLUTION: In an adhesive film obtained by installing an anchor layer, and an adhesive layer in this order on one surface of a base material made of a polyethylene terephthalate resin, the adhesive layer is made of a silicone resin obtained by curing a silicone composition by an additive reaction, and the anchor layer contains each of colloidal silica, a resin, ethyl silicate hydrolyzate and polystyrene sulfonate in a specific range.SELECTED DRAWING: None

Description

In the present invention, an adhesive layer made of a silicone-based resin obtained by curing a silicone composition by an addition reaction is provided on a base film having good reworkability to be attached to or removed from an adherend having a smooth surface. It is related to the sticking film. In addition, its use is a protective film when heat resistance is required for electronic parts and other articles.

Conventionally, a sticking film having an adhesive layer made of a silicone resin on a base material has been provided. It can be easily attached to an adherend having a smooth surface, and when it is not needed, the adhesive film can be removed without adhesive residue on the adherend, and does not affect the adherend. It was. Some of such films are used as protective films in the process of manufacturing electronic parts and the like, and are often used as protective films in a high temperature environment. For example, an adhesive tape having an adhesive layer made of a silicone-based adhesive composition having specific physical properties has been proposed. (Patent Document 1)

Here, when a polyethylene terephthalate (hereinafter abbreviated as PET) film is used as the base material of the sticking film, a heat treatment step of applying and drying the silicone resin forming the adhesive layer, or sticking to an adherend. When exposed to a high-temperature environment such as wearing and heat-treating, oligomer components such as cyclic trimer contained in the PET film base material migrate to the surface of the adhesive layer having a low crosslink density. If the sticking film is stuck to the adherend in this state, a problem occurs in which the oligomer component contaminates the adherend. In particular, when the treatment temperature exceeds 150 ° C., the amount of the oligomer component transferred increases. In addition, the same problem may occur even after long-term use. In Patent Document 1, no consideration is given to the transfer of the oligomer component derived from the PET film base material.

As a method of preventing the transfer of the oligomer component derived from the PET film base material to the surface of the adhesive layer, it is generally considered to increase the crosslink density of the adhesive layer, but in this method, the flexibility of the silicone adhesive layer is increased. It lowers and becomes difficult to attach to the adherend. Further, as a countermeasure, if the adhesiveness-imparting component in the adhesive layer is increased in order to increase the adhesive force with the adherend, when the adhesive film is removed from the adherend, the adherend surface or the adherent film is removed. It may be damaged or adhesive residue may occur, and as a result, both prevention of migration of the oligomer component and good reworkability have not been realized.

As another method for preventing the transfer of the oligomer component derived from the PET film substrate, there is a method of performing an additional treatment in order to remove the oligomer component in the polyester resin. For example, the polyester resin is subjected to an alkali metal salt having a specific concentration and / or an alkali. A method of contacting with an aqueous solution of an earth metal salt has been proposed. (Patent Document 2) However, the PET film subjected to the additional treatment becomes expensive, and the manufacturing cost of the adhesive film increases.

Further, as a method for preventing migration of oligomer components, an optical polyester film composed of a polyester film and a coating layer of a composition composed of an acrylic resin and a cross-linking agent provided on at least one surface thereof has been proposed (Patent Document 3). ) However, the acrylic resin having an increased crosslink density for the purpose of preventing oligomer migration has fewer functional groups capable of binding to the silicone resin forming the adhesive layer, and a silicone resin adhesive layer is provided on the acrylic resin. At that time, the adhesive force between the acrylic resin and the adhesive layer becomes low, and the adhesive layer peels off or adhesive residue occurs when the acrylic resin is peeled off from the adherend.

Japanese Unexamined Patent Publication No. 2012-151360 Japanese Unexamined Patent Publication No. 2004-10657 Japanese Unexamined Patent Publication No. 2005-89622

In order to solve the above-mentioned problems, the present invention has good adhesion between the PET film base material and the silicone-based adhesive layer, and the adhesive film is attached to the adherend, and is subjected to high-temperature treatment and long length. Even when used for a period of time, the oligomer component of the base material does not contaminate the adherend, and it has flexibility and good reworkability that can be easily attached to or removed from the adherend. It is an object of the present invention to provide a sticking film having.

In view of the above problems, the present inventor has made a sticking film in which an anchor layer and a silicone-based adhesive layer are sequentially laminated on at least one surface of a PET film base material, wherein the anchor layer is a resin, an ethyl silicate hydrolyzate, or a colloidal. By containing silica and polystyrene sulfonic acid, the anchor layer blocks the migration of the oligomer component derived from the PET film substrate after the heat treatment step of applying and drying the adhesive layer or after a long period of time. Then, it was found that it has an effect of preventing migration to the surface side of the adhesive layer. As a result, even when the adhesive film is attached to the adherend and treated at a high temperature or used for a long period of time, the oligomer component of the base material does not contaminate the adherend and has heat resistance. Further, they have found that the object of the present invention of good reworkability is achieved, and have completed the present invention.

The first invention is a sticking film in which an anchor layer and an adhesive layer are laminated in this order on one side of a base material made of polyethylene terephthalate resin, and the adhesive layer is made of a silicone resin obtained by curing a silicone composition by an addition reaction. The anchor layer is characterized by containing 40 to 85% by weight of colloidal silica, 10 to 30% by weight of resin, 5 to 30% by weight of ethyl silicate hydrolyzate and 1 to 30% by weight of polystyrene sulfonic acid. It is a sticking film.

The second invention is the sticking film according to the first invention, wherein the resin contained in the anchor layer is a polyester resin, a urethane resin, or an acrylic urethane resin.

In the third invention, the adhesive layer is formed by curing a silicone composition containing at least a vinyl group-containing polydimethylsiloxane composition, a SiH group-containing organohydrogenpolysiloxane, and a silicone resin as the silicone composition by an addition reaction. The adhesive film according to either the first invention or the second invention, which is made of a silicone resin.

The fourth invention is the sticking film according to any one of the first to third inventions, wherein the thickness of the anchor layer is 0.05 to 3.00 μm.

According to the present invention, in a sticking film in which an anchor layer and a silicone resin adhesive layer are sequentially laminated on at least one side of a PET film base material, the anchor layer comprises a resin, an ethyl silicate hydrolyzate, colloidal silica and polystyrene sulfonic acid. By containing the adhesive layer, the anchor layer blocks the migration of the oligomer component of the PET film substrate after the heat treatment step of applying and drying the adhesive layer or after a long period of time, and the surface of the adhesive layer. Do not move to the side. Further, even when the adhesive film is attached to an adherend and treated at a high temperature or used for a long period of time, the oligomer component of the base material does not contaminate the adherend and has heat resistance. Further, it is possible to provide a sticking film having good reworkability.

Further, by assuming that the anchor layer contains an ethyl silicate hydrolyzate and polystyrene sulfonic acid in addition to the resin and colloidal silica, the ethyl silicate hydrolyzate is polymerized and / or condensed, and also with colloidal silica. By forming a siloxane polymer structure by bonding, even if the anchor layer is thin, it can be used for high temperature treatment or for a long time compared to the case where the anchor layer does not contain ethyl silicate hydrolyzate and polystyrene sulfonic acid. The performance of blocking the migration of oligomer components can be ensured.

The adhesive film of the present invention will be described in more detail below based on its components.

(overall structure)
The adhesive film of the present invention is an adhesive film in which an anchor layer and a silicone-based adhesive layer are sequentially laminated on at least one surface of a PET film base material, and the anchor layer is a resin, an ethyl silicate hydrolyzate, colloidal silica, and polystyrene sulfone. It contains an acid.

(Base film)
As the base material used in the present invention, for example, a biaxially stretched polyethylene terephthalate (PET) film is preferable from the viewpoint of handleability and cost of the adhesive layer during thermal cross-linking. The thickness of the base film is usually in the range of 4 to 400 μm, and preferably 5 to 100 μm.

As the PET film, a PET film whose surface is treated with active rays can be used. Examples of the treatment method using active rays include corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, flame treatment, and the like.

(Anchor layer)
In the present invention, an anchor layer is provided between the base material and the adhesive layer. By containing the resin, ethyl silicate hydrolyzate, polystyrene sulfonic acid and colloidal silica in the anchor layer, the adhesion between the PET film base material and the silicone-based adhesive layer and the anchor layer is maintained, and the PET film base material is maintained. Anchor that prevents the migration of derived oligomer components and does not leave adhesive residue on the adherend when the adhesive film is peeled off from the adherend even after passing through a high temperature environment after the adherend is attached. Become a layer.

The thickness of the anchor layer is preferably 0.05 to 3.00 μm, and more preferably 0.10 to 1.50 μm. If the thickness of the anchor layer is less than 0.05 μm, the adhesion between the anchor layer and the base material and between the anchor layer and the adhesive layer is insufficient. In addition, the ability to prevent migration of oligomer components is insufficient. If the thickness is thicker than 3.00 μm, the flexibility is lost and the anchor layer is cracked when the adhesive film is handled. The price will also be higher.

In the anchor layer of the present invention, the fluidity of the coating liquid and even if the anchor layer becomes a thin film, unevenness does not occur, and the anchor layer can be uniformly dispersed in the anchor layer to exert its function. The obtained colloidal silica is preferably used.

The content of the colloidal silica in the anchor layer is preferably in the range of 40 to 85% by weight. Within this range, the anchor layer has sufficient heat resistance, and when the adhesive film and the adherend are peeled off after being attached to the adherend and subjected to a high temperature environment. , No adhesive residue is generated on the adherend of the adhesive layer. If the content is less than 40% by weight, sufficient heat resistance in the present invention cannot be obtained, and when the adhesive film and the adherend are peeled off after passing through a high temperature environment, the adhesive layer adheres to the adherend. May produce the rest. When the content exceeds 85% by weight, the ratio of other components becomes relatively small, and the heat resistance, which is a function of the anchor layer of the present invention, the adhesion to the base material and the silicone adhesive layer, and the oligomer derived from the PET film base material The migration prevention performance of each component is reduced. As a result, when the adhesive film is peeled off during the handling of the adherend to which the adhesive film of the present invention is attached, or when the adhesive film and the adherend are peeled off after passing through a high temperature environment, the adhesive layer Adhesive residue may be left on the adherend, or the adherend may be contaminated by oligomers.

As the colloidal silica, those having a primary particle size of 1 nm or more and less than 50 nm can be used satisfactorily, and those having a primary particle size of 1 nm or more and less than 30 nm can be used more satisfactorily. When the primary particle size is 50 nm or more, it causes unevenness on the surface of the anchor layer near the lower limit of the thickness of the anchor layer, and affects the smoothness of the surface of the silicone adhesive layer. Those having a primary particle size of less than 1 nm are difficult to obtain as commercial products.

As the resin used for the anchor layer of the present invention, a resin suitable for maintaining the adhesion between the PET film base material and the silicone-based adhesive layer and the anchor layer is used, and urethane resin, polyester resin, and acrylic urethane resin are used. Can be suitably used. In particular, acrylic urethane resin is preferably used.

As the acrylic urethane resin, an acrylic urethane resin having a structure in which an acrylic polyol-based resin having a hydroxyl group and a (meth) acryloyl group and an isocyanate-based cross-linking agent are crosslinked is preferable from the viewpoint of flexibility and heat resistance. Examples of the isocyanate-based cross-linking agent include tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), tetraxylylene diisocyanate (TMXDI), isophorone diisoanate (IPDI), and norbornene. Diisocyanate (NBDI), hexamethylene diisocyanate (HMDI), trimethylhexamethylene diisocyanate (TMHMDI), naphthalenediocyanate (NDI), diphenyl ether diisocyanate (PEDI), dianisidine diisocyanate (DADI), p-phenylenediocyanate (PPDI), isopropyridenebis -4-Cyclohexyldiisocyanate (IPCI), lysine diisocyanate (LDI), trimethylhexamethylene diisocyanate (TMDI), diimate diisocyanate (DDI), etc., and compounds such as adduct, biuret, isocyanurate, etc., to which the compounds are associated However, it is not limited to these. These compounds may be used alone or in combination of two or more.

By using a resin having a bifunctional or higher functional group as the resin used for the anchor layer of the present invention, the adhesion to each component of the PET film base material and the anchor layer and the silicone adhesive layer becomes good.

The content of the resin in the anchor layer in the present invention is preferably in the range of 10 to 30% by weight. If the content is less than 10% by weight, the adhesion of the anchor layer to the base material is insufficient, and it is difficult to obtain the desired performance. When the content exceeds 30% by weight, the ratio of other components becomes relatively small, and the heat resistance, which is a function of the anchor layer of the present invention, the adhesion to the base material and the silicone adhesive layer, and the oligomer derived from the PET film base material The migration prevention performance of each component is reduced. As a result, when the adhesive film is peeled off during the handling of the adherend to which the adhesive film of the present invention is attached, or when the adhesive film and the adherend are peeled off after passing through a high temperature environment, the adhesive layer Adhesive residue may be left on the adherend, or the adherend may be contaminated by oligomers.

The anchor layer of the present invention contains an ethyl silicate hydrolyzate and polystyrene sulfonic acid, and has a silicate polymer structure to prevent migration of oligomer components derived from a PET film substrate.

The ethyl silicate hydrolyzate hydrolyzes ethyl silicate in an organic solvent such as an alcohol solvent in the presence of a specific amount of water and a condensation catalyst, or in the presence of a specific amount of water and in the absence of a condensation catalyst. Can be obtained. Alternatively, a commercially available ethyl silicate hydrolyzate may be used.

The content of the ethyl silicate hydrolyzate in the anchor layer is preferably in the range of 5 to 30% by weight. If the content is less than 5% by weight, the crosslink density of the silicate polymer structure is low, and the ability to prevent the migration of the oligomer component derived from the PET film substrate cannot be obtained. When the content exceeds 30% by weight, the ratio of other components becomes relatively small, sufficient heat resistance in the present invention cannot be obtained, and the adhesive film and the adherend are peeled off after passing through a high temperature environment. Occasionally, adhesive residue on the adherend of the adhesive layer may occur. In addition, the migration prevention performance of the oligomer component derived from the PET film substrate is lowered, and the adherend is contaminated by the oligomer component.

In the present invention, polystyrene sulfonic acid acts as a catalyst when the ethyl silicate hydrolyzate becomes a silicate polymer structure. Further, when the anchor layer and the adhesive layer in the present invention are coated, if the base material is charged, coating unevenness may occur. This can be dealt with by introducing a conductive material into the anchor layer, but polystyrene sulfonic acid also has conductivity and also has a function as the conductive material, so that it does not contain other conductive materials. Antistatic is also possible.

The content of the polystyrene sulfonic acid in the anchor layer is preferably 1 to 30% by weight. If the content is less than 1% by weight, it does not work as a catalyst or the antistatic performance is weakened. When the content exceeds 30% by weight, the ratio of other components becomes relatively small, and the heat resistance, which is a function of the anchor layer of the present invention, the adhesion to the base material and the silicone adhesive layer, and the oligomer derived from the PET film base material The migration prevention performance of each component is reduced. As a result, when the adhesive film is peeled off during the handling of the adherend to which the adhesive film of the present invention is attached, or when the adhesive film and the adherend are peeled off after passing through a high temperature environment, the adhesive layer Adhesive residue may be left on the adherend, or the adherend may be contaminated by oligomers.

(Adhesive layer)
The adhesive layer of the adhesive film of the present invention needs to be securely attached to the adherend and can be peeled off without adhesive residue even after being exposed to a high temperature environment. As the adhesive layer for such applications, an addition reaction type silicone resin in which the silicone composition is cured by an addition reaction by heat can be particularly preferably used because of its heat resistance and flexibility. By forming an adhesive layer with an addition reaction type silicone resin and combining it with the anchor layer of the present invention, no oligomers derived from the PET film substrate are generated even after exposure to a high temperature environment, and it is easy without adhesive residue from the adherend. It can be a sticking film that peels off.

The addition-reaction type silicone resin used for the pressure-sensitive adhesive layer of the present invention includes a polyorganosiloxane and a silicone resin having two or more vinyl groups in one molecule as a silicone composition, and an organohydro having a SiH group as a curing agent. Those obtained by thermosetting by the addition reaction of gempolysiloxane are preferably used. A suitable adhesive layer can be obtained by containing the polyorganosiloxane, the silicone resin and the organohydrogenpolysiloxane having a SiH group as the silicone composition and heat-curing the mixture.

The adhesive layer using the silicone resin will be described in more detail below.

(Silicone resin adhesive layer)
As the properties of the silicone resin used for the adhesive layer of the present invention, it is required that the surface of the adhesive layer follows the surface of the adherend even with respect to the surface of the adherend having flexibility like rubber. Further, at the time of peeling, it is required that the peeling force can be easily reduced. Further, in order to provide an adhesive layer with a thickness of at least 5 μm or more only by coating and heat treatment, the curing reaction of the silicone composition is carried out at a low temperature of 150 ° C. or less in a short time under an addition reaction catalyst such as a platinum catalyst. Diorgan polysiloxane and silicone resin having two or more vinyl groups in one molecule, which are transparent, heat resistant, excellent in compression set, low viscosity and liquid type, and SiH as a curing agent. It is preferable to use an addition reaction type liquid silicone composition that is thermally cured by an addition reaction with an organohydrogenpolysiloxane having a group.

Diorganopolysiloxanes having two or more vinyl groups in one molecule include linear diorganopolysiloxanes having vinyl groups only at both ends and linear diorganopolysiloxanes having vinyl groups at both ends and side chains. It is preferable to use at least one selected from an organopolysiloxane, a branched diorganopolysiloxane having a vinyl group only at the terminal, and a branched diorganopolysiloxane having a vinyl group at the terminal and side chains.

One form of these diorganopolysiloxanes is a linear diorganopolysiloxane having vinyl groups only at both ends, which is a compound represented by the following general formula (Chemical Formula 1).

(In the formula, R represents the following organic group and n represents an integer.)

(In the formula, R represents the following organic group, and n and m represent integers.)

The organic group (R) bonded to the silicon atom other than the vinyl group may be different or the same, and specific examples thereof include an alkyl group such as a methyl group, an ethyl group and a propyl group, and an aryl group such as a phenyl group and a trill group. , Or monovalent hydrocarbon groups excluding homologous or heterologous unsubstituted or substituted aliphatic unsaturated groups in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with halogen atoms, cyano groups, etc. And preferably, at least 50 mol% thereof is a methyl group, and this diorganopolysiloxane may be used alone or in a mixture of two or more kinds.

The linear diorganopolysiloxane having vinyl groups at both ends and side chains is a compound in which a part of R in the above general formula (Chemical Formula 1) is a vinyl group. The branched polyorganosiloxane having a vinyl group only at the terminal is a compound represented by the above general formula (Chemical Formula 2). The branched polyorganosiloxane having a vinyl group at the terminal and the side chain is a compound in which a part of R in the above general formula (Chemical Formula 2) is a vinyl group.

The weight average molecular weight of the diorganopolysiloxane having two or more vinyl groups in one molecule is preferably in the range of 20,000 to 700,000. If the weight average molecular weight of the diorganopolysiloxane is less than 20,000, the curability is lowered and the adhesive strength to the adherend is lowered. On the other hand, if it exceeds 700,000, the viscosity of the composition becomes too high and it becomes difficult to stir during production.

The silicone resin used for the adhesive layer of the present invention includes M unit (R ₃ SiO _1/2 : R is a monovalent organic group such as a methyl group and a phenyl group), D unit (R ₂ SiO _2/2 ), and the like. Silicone resins consisting of T units (RSiO _3/2 ) and Q units (SiO _4/2 ) can be used, but since the effect of improving the adhesive strength of the adhesive layer is particularly large, from M units and Q units. It is preferable to contain a so-called conventionally known MQ type organopolysiloxane resin (hereinafter, may be abbreviated as MQ resin). The content of the MQ resin in the adhesive layer is preferably in the range of 0.01 to 20.00% by weight. In particular, the range of 0.10 to 15.00% by weight is more preferable. If the content is less than 0.01% by weight, it is difficult to obtain the effect of improving the adhesive strength. If the content exceeds 20.00% by weight, the adhesive strength becomes too strong, and when the adhesive layer is peeled from the adherend, the thin film substrate or the thin film sheet which is the adherend may be damaged.

In the combination with the diorganopolysiloxane and the silicone resin, the curing agent used for the curing reaction may be a known curing agent, and examples of the curing agent include organohydrogenpolysiloxane having a SiH group in the molecule. Be done. Among them, it is particularly preferable to use a methylhydrogensiloxane-dimethylsiloxane copolymer. As the methylhydrogensiloxane moiety of the copolymer, one having at least three hydrogen atoms bonded to a silicon atom in one molecule is preferably used, but from practical use, one having two ≡SiH bonds in the molecule is used. The total amount may be up to 50% by weight, and the remainder may contain at least 3 ≡SiH bonds in the molecule. As the shape of the molecule, a linear, branched, or cyclic molecule can be used.

Further, the molar ratio (A) / (B) of the SiH group (B) in the organohydrogenpolysiloxane to the vinyl group (A) in the diorganopolysiloxane having the vinyl group is 1.0 to 2.0. It is preferable to mix so as to be in the range of. If the molar ratio (A) / (B) is less than 1.0, the curing density may be insufficient, and the cohesive force and holding force may decrease accordingly. On the contrary, if it exceeds 2.0, the curing density becomes low. It becomes high, and an appropriate adhesive force cannot be obtained, and it becomes difficult to obtain a sufficient adhesive force due to the bond between the hydroxyl group on the anchor surface and the SiH group.

The addition reaction catalysts used in the curing reaction are platinum chloride acid, an alcohol solution of platinum chloride acid, a reaction product of platinum chloride acid and alcohol, a reaction product of platinum chloride acid and an olefin compound, and platinum chloride acid and a vinyl group-containing siloxane. Examples thereof include a platinum-olefin complex, a platinum-vinyl group-containing siloxane complex, a rhodium complex, and a ruthenium complex. Further, those obtained by dissolving and dispersing these substances in a solvent such as isopropanol or toluene or silicone oil may be used. The cured adhesive layer has flexibility similar to that of silicone rubber, and this flexibility facilitates adhesion to the adherend.

The amount of the addition reaction catalyst added is preferably 5 to 2,000 ppm, particularly 10 to 500 ppm, as a noble metal content with respect to 100 parts by weight of the total amount of the silicone composition. If it is less than 5 ppm, the curability is lowered, the curing density is lowered, and the holding power may be lowered. If it exceeds 2,000 ppm, the usable time of the coating liquid may be shortened.

Commercially available shapes of the silicone composition according to the present invention include solvent-free type, solvent type, and emulsion type, and any type can be used. Among them, the solvent-free type has great advantages in terms of safety, hygiene, and air pollution because it does not use a solvent. However, even if it is a solvent-free type, in order to adjust the viscosity to obtain the desired film thickness, if necessary, aromatic hydrocarbon solvents such as toluene and xylene, and fats such as hexane, heptane, octane, and isoparaffin are used. Group hydrocarbon solvents, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and isobutyl acetate, ether solvents such as diisopropyl ether and 1,4-dioxane, or mixed solvents thereof, etc. Is used.

The amount of the solvent added is preferably 20 to 1,000 parts by weight, particularly 25 to 900 parts by weight, based on 100 parts by weight of the total amount of the silicone composition. If it is less than 20 parts by weight, the adhesion between the adhesive layer and the anchor layer may decrease and peel off. If it exceeds 1,000 parts by weight, the viscosity of the coating liquid of the silicone composition becomes too low. During the period from the latter to the curing, a part of the coated adhesive layer flows, and the smoothness of the surface of the adhesive layer deteriorates.

As the properties of the adhesive layer of the present invention, it is required to have flexibility like rubber and to follow the unevenness of the surface of the adherend at the time of sticking to the adherend to secure the adhesive force. Then, for example, when used as a support film for manufacturing the parts, the film thickness of the adhesive layer is preferably at least 5 μm or more, usually 10 to 100 μm in order to secure a shearing force in the contact surface direction of the adhesive layer with respect to the adherend. More preferably, it is 20 to 50 μm. If it is less than 5 μm, the shearing force in the direction of the contact surface of the protective member with respect to the adherend cannot be secured, and the adhesive film is easily peeled off from the adherend, especially during long-term attachment. Further, when the thickness of the adhesive layer exceeds 100 μm, the amount of the resin constituting the adhesive layer increases, which leads to an increase in the manufacturing cost of the adhesive film.

As a method for forming the adhesive layer in the present invention, a method of dissolving the resin constituting the adhesive layer in an organic solvent and applying a resin solution having an adjusted viscosity, or a method of dispersing the resin constituting the adhesive layer in water and applying the coating. A known method such as a method can be used. As the organic solvent, a general organic solvent can be used without particular limitation. For example, the above-mentioned organic solvent for adjusting the viscosity can be mentioned, but the present invention is not limited thereto.

Examples of the coating method for the adhesive layer of the present invention include a comma knife coater, a die coater, and a reverse coater.

(Separator)
In the present invention, for the purpose of preventing dirt and foreign matter from adhering to the surface of the adhesive layer and improving the handling of the adhesive film, it is preferable to use a separator made of a plastic film attached to the adhesive layer surface. The separator is made of a highly peelable plastic film, and if desired, a separator having a release agent formed on the surface of the plastic film is used.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In addition, "part" in each Example shows a part by weight unless otherwise specified.

(Adjustment of ethyl silicate hydrolyzate)
Isopropyl alcohol, water, and hydrochloric acid were added to ethyl silicate according to the following formulation, and the mixture was stirred and left to stand for 12 hours to obtain a hydrolyzate of ethyl silicate (material D in Tables 2 and 3).

Ethyl silicate: Tama Kagaku Kogyo silicate 40 25.0 parts by weight Isopropyl alcohol (IPA) 72.0 parts by weight Water 2.0 parts by weight
1.0 part by weight of hydrochloric acid

(Examples 1 to 11, Comparative Examples 1 to 10)
A PET film having a thickness of 50 μm was used as a base material, and one side of the PET film was subjected to corona discharge treatment and mixed according to the formulations shown in Examples 1 to 11 and Comparative Examples 1 to 10 in Tables 2 and 3, respectively. Each anchor layer coating liquid is adjusted so that the thickness after drying becomes the respective values shown in Table 2, and the coating is applied to the corona discharge-treated surface of the substrate, and the organic solvent is removed at 100 ° C. for 2 minutes. Then, each anchor layer was formed by heating so that the ethyl silicate hydrolyzate had a siloxane polymer structure. Each adhesive layer coating solution shown in Table 1 below is coated on it so that the thickness after drying is 15 μm, and then heated and dried at 100 ° C. for 2 minutes to remove the organic solvent, and then 100 ° C. at 150 ° C. The coating liquid was cured by heating for seconds to form an adhesive layer, and the adhesive films of Examples 1 to 11 and Comparative Examples 1 to 10 were prepared. Each of the prepared adhesive films is cut to a width of 25 mm, the adhesive layer of each adhesive film is attached to a glass plate having a thickness of 1 mm, heated at 180 ° C. for 2 minutes, cooled to room temperature, and then attached to each glass plate. A laminate to which a wearing film was attached was produced.

単位：重量部

Unit: Weight part

The material composition ratios and evaluation results of each example and comparative example are shown in Tables 2 and 3, and each evaluation method is shown below.

(Evaluation method)

(Evaluation of adhesion between base material and anchor layer)
In the films in which the anchor layers of Examples 1 to 11 and Comparative Examples 1 to 10 were installed, the anchor layer was rubbed with a finger, and the adhesion between the base material and the anchor layer was visually observed and evaluated according to the following criteria.
⊚: No drop off from the base material after 50 finger rubbing.
◯: Finger rubbing 10 times or more and less than 50 times caused the material to fall off.
X: Less than 10 times of finger rubbing, there is a drop from the base material.

(Evaluation of adhesion between anchor layer and adhesive layer)
The adhesive layers of the adhesive films of Examples 1 to 11 and Comparative Examples 1 to 10 were rubbed with a finger, and the adhesion between the anchor layer and the adhesive layer was visually observed and evaluated according to the following criteria.
⊚: No drop off from the base material after 15 finger rubbing.
◯: Finger rubbing 5 times or more and less than 15 times caused to fall off from the base material.
X: With less than 5 finger rubs, there is a drop from the base material.

(Oligomer migration prevention evaluation)
In the laminate of the glass plate and each adhesive film produced in Examples 1 to 11 and Comparative Examples 1 to 10, the haze value of the laminate before and after heating at 180 ° C. for 2 minutes was set by a method based on JIS-K7136. The measurement was performed, the difference was evaluated according to the following criteria, and the oligomer transfer preventive property was evaluated.
◯: The difference in haze value before and after heating is less than 1.0%.
Δ: The difference in haze value before and after heating is 1.0% or more and less than 5.0%.
×: Difference in haze value before and after heating is 5.0% or more Measuring instrument: NDH-2000 manufactured by Nippon Denshoku Industries Co., Ltd.

(Flexibility evaluation)
Anchor of the adhesive film when the adhesive film is peeled 180 ° at a speed of 300 mm / min in the laminate of the glass plate and each adhesive film produced in Examples 1 to 11 and Comparative Examples 1 to 10. The peelability was evaluated by a method of visually confirming the occurrence of cracks in the layer.
Evaluation Criteria ◯: The anchor layer did not crack during peeling, and peeling was easy.
X: The anchor layer was cracked during peeling.

(Evaluation of heat resistance and adhesive residue of adhesive layer)
In the laminate of the glass plate and each adhesive film produced in Examples 1 to 11 and Comparative Examples 1 to 10, when the adhesive film was peeled by 180 ° at a speed of 300 mm / min, after the adhesive film was peeled off. The adhesive residue was evaluated by a method of visually confirming the adhesion of the adhesive layer to the glass plate.
Evaluation Criteria ○: No adhesion of the adhesive layer on the glass plate.
X: Adhesive layer adheres to the glass plate.

Claims (4)

A sticking film in which an anchor layer and an adhesive layer are laminated in this order on one side of a base material made of polyethylene terephthalate resin, wherein the adhesive layer is made of a silicone resin obtained by curing a silicone composition by an addition reaction, and the anchor layer. However, the adhesive film is characterized by containing 40 to 85% by weight of colloidal silica, 10 to 30% by weight of a resin, 5 to 30% by weight of an ethyl silicate hydrolyzate, and 1 to 30% by weight of polystyrene sulfonic acid. .. The sticking film according to claim 1, wherein the resin contained in the anchor layer is a polyester resin, a urethane resin, or an acrylic urethane resin. The adhesive layer is made of a silicone resin obtained by curing a silicone composition containing at least a vinyl group-containing polydimethylsiloxane composition, a SiH group-containing organohydrogenpolysiloxane, and a silicone resin as the silicone composition by an addition reaction. The sticking film according to claim 1 or 2, wherein the sticking film is characterized by. The adhesive film according to any one of claims 1 to 3, wherein the thickness of the anchor layer is 0.05 to 3.00 μm.