JP7285612B2 - Adhesive film for heat-resistant protection - Google Patents

Description

In the present invention, an adhesive layer made of a silicone-based resin obtained by curing a silicone composition through an addition reaction is provided on a base film, which has good reworkability for attaching to and removing from an adherend having a smooth surface. It relates to a sticking film. In addition, it is used as a protective film for electronic parts and other articles that require heat resistance.

Conventionally, an adhesive film has been provided in which an adhesive layer made of a silicone resin is provided on a base material. It can be easily attached to an adherend with a smooth surface, and when it is not needed, the adhesive film can be removed without leaving any adhesive residue on the adherend without affecting the adherend. rice field. Some of such films are used as protective films during the manufacture of electronic parts and the like, and are often used as protective films in high-temperature environments. For example, pressure-sensitive adhesive tapes having pressure-sensitive adhesive layers made of silicone-based pressure-sensitive adhesive compositions with specific physical properties have been proposed. (Patent document 1)

Here, when a polyethylene terephthalate (hereinafter abbreviated as PET) film is used as the base material of the adhesive film, the heat treatment step of applying and drying the silicone resin forming the adhesive layer and the adhesion to the adherend are performed. When exposed to a high-temperature environment such as by wearing and heat-treating, oligomer components such as cyclic trimers contained in the PET film base migrate to the surface of the adhesive layer with a low cross-linking density. If the adhesive film is stuck to the adherend in this state, the oligomer component will contaminate the adherend. In particular, when the treatment temperature exceeds 150° C., the migration amount of oligomer components increases. Also, similar problems may occur during long-term use. Incidentally, in Patent Document 1, no consideration is given to migration of the oligomer component derived from the PET film substrate.

As a method for preventing the migration 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. It lowers, making it difficult to adhere to the adherend. As a countermeasure against this problem, increasing the tackiness-imparting component in the adhesive layer in order to increase the adhesive strength with the adherend may cause the surface of the adherend and the adhesive film to be removed when the adhesive film is removed from the adherend. As a result, it has not been possible to achieve both prevention of migration of the oligomer component and good reworkability.

Another method for preventing the migration of oligomer components derived from the PET film base material is to perform an additional treatment to remove the oligomer components in the polyester resin. A method of contact treatment 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.

In addition, as a method for preventing migration of oligomer components, an optical polyester film has been proposed which comprises a polyester film and a coating layer of a composition comprising an acrylic resin and a cross-linking agent provided on at least one side thereof (Patent Document 3). ), but the acrylic resin with increased cross-linking density for the purpose of preventing migration of oligomers has fewer functional groups that can bond with the silicone resin forming the adhesive layer, and a silicone resin adhesive layer is provided on the acrylic resin. In this case, the adhesive strength between the acrylic resin and the adhesive layer becomes low, and peeling of the adhesive layer and adhesive residue occur when the adhesive layer is peeled off from the adherend.

JP 2012-151360 A JP 2004-10657 A JP-A-2005-89622

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

In view of the above problems, the present inventors have proposed an adhesive film in which an anchor layer and a silicone-based adhesive layer are sequentially laminated on at least one side of a PET film substrate, wherein the anchor layer is a resin, an ethylsilicate hydrolyzate, or a colloidal adhesive. By containing silica and polystyrene sulfonic acid, the anchor layer blocks the migration of the oligomer component derived from the PET film substrate in the heat treatment step of applying and drying the adhesive layer or after a long period of time. However, the inventors have 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 an adherend and subjected to high-temperature treatment or used for a long period of time, the oligomer component of the substrate does not contaminate the adherend, and the film is heat resistant. The inventors have also found that the object of the present invention that the reworkability is good can be achieved, and have completed the present invention.

A first invention is an adhesive 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 contains at least a vinyl group-containing polyorganosiloxane and a SiH group as a curing agent. and a silicone resin that is a cured product of an addition reaction type silicone composition containing a silicone resin. %, 5-30% by weight of ethyl silicate hydrolyzate and 1-30% by weight of polystyrene sulfonic acid.

In a second invention, the adhesive according to the first invention is characterized in that the resin contained in the anchor layer is any one selected from polyester resins, urethane resins, and acrylic urethane resins. It's a film.

A third invention is the adhesive film according to either the first invention or the second invention, wherein the vinyl group-containing polyorganosiloxane is a vinyl group-containing polydimethylsiloxane.

A fourth invention is the adhesive 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 the adhesive film obtained by sequentially laminating an anchor layer and a silicone resin adhesive layer on at least one surface of a PET film substrate, the anchor layer contains a resin, an ethylsilicate hydrolyzate, colloidal silica and polystyrene sulfonic acid. By containing it, in the heat treatment step of applying and drying the adhesive layer or after a long period of time, the anchor layer blocks the migration of the oligomer component of the PET film base material, 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 subjected to high temperature treatment or used for a long period of time, the oligomer component of the substrate does not contaminate the adherend, and heat resistance, And it is possible to provide an adhesive film having good reworkability.

In addition, the anchor layer contains an ethyl silicate hydrolyzate and polystyrene sulfonic acid in addition to the resin and colloidal silica, whereby the ethyl silicate hydrolyzate is polymerized and/or condensed, and colloidal silica By forming a siloxane polymer structure by bonding, even if the thickness of the anchor layer is thinner than when the anchor layer does not contain ethyl silicate hydrolyzate and polystyrene sulfonic acid, it can be used for high temperature processing and for a long time. The ability to block migration of oligomer components can be ensured.

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

(overall structure)
The adhesive film of the present invention is an adhesive film obtained by sequentially laminating an anchor layer and a silicone-based adhesive layer on at least one side of a PET film substrate, wherein the anchor layer comprises a resin, an ethylsilicate hydrolyzate, colloidal silica and polystyrene sulfone. It contains an acid.

(Base film)
As the substrate used in the present invention, for example, a polyethylene terephthalate (PET) film biaxially stretched is preferable from the standpoints of handling during thermal crosslinking of the adhesive layer and cost. The thickness of the substrate film used is usually 4 to 400 μm, preferably 5 to 100 μm.

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

(anchor layer)
In the present invention, an anchor layer is provided between the substrate and the adhesive layer. Since the anchor layer contains a resin, ethyl silicate hydrolyzate, polystyrene sulfonic acid and colloidal silica, the adhesiveness between the PET film substrate and the silicone adhesive layer and the anchor layer is maintained, and the PET film substrate An anchor that prevents the migration of the oligomer component derived from the adhesive layer and does not cause adhesive residue on the adherend when the adhesive film is peeled off from the adherend even after the adherend has been subjected to a high temperature environment. layer.

The thickness of the anchor layer is preferably 0.05-3.00 μm, more preferably 0.10-1.50 μm. If the thickness of the anchor layer is less than 0.05 μm, the adhesive strength between the anchor layer and the substrate and between the anchor layer and the pressure-sensitive adhesive layer will be insufficient. In addition, the ability to prevent migration of oligomer components is insufficient. If the thickness is more than 3.00 μm, the adhesive film loses flexibility and cracks occur in the anchor layer during handling. Also, the price will be higher.

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

The colloidal silica content 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 after the adhesive film has been attached to the adherend and passed through a high temperature environment, when the adhesive film and the adherend are peeled off. , The adhesive layer does not leave adhesive residue on the adherend. 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 does not adhere to the adherend. may produce a residue. When the content exceeds 85% by weight, the proportion of other components is relatively low, and the functions of the anchor layer of the present invention, such as heat resistance, adhesive strength with the base material and silicone adhesive layer, and oligomer derived from the PET film base material. The anti-migration performance of the components is lowered respectively. As a result, the adhesive film may peel off during handling of an 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 may be damaged. Adhesive residue may be left on the adherend, or the adherend may be contaminated with the oligomer.

Colloidal silica having a primary particle size of 1 nm or more and less than 50 nm can be used favorably, and colloidal silica having a primary particle size of 1 nm or more and less than 30 nm can be used more favorably. When the primary particle size is 50 nm or more, it causes irregularities on the surface of the anchor layer near the lower limit of the thickness of the anchor layer, affecting 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 to be used for the anchor layer of the present invention, a resin suitable for maintaining adhesion between the anchor layer and the PET film substrate and silicone adhesive layer is used, and urethane resin, polyester resin and acrylic urethane resin are used. It can be used preferably. In particular, acrylic urethane resin is preferably used.

The acrylic urethane resin is preferably an acrylic urethane resin having a structure in which an acrylic polyol resin having a hydroxyl group and a (meth)acryloyl group and an isocyanate crosslinking agent are crosslinked, 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 diisocyanate (IPDI), norbornene. Diisocyanate (NBDI), hexamethylene diisocyanate (HMDI), trimethylhexamethylene diisocyanate (TMHMDI), naphthalene diisocyanate (NDI), diphenyl ether diisocyanate (PEDI), dianisidine diisocyanate (DADI), p-phenylene diisocyanate (PPDI), isopropylidenebis -4-cyclohexyl diisocyanate (IPCI), lysine diisocyanate (LDI), trimethylhexamethylene diisocyanate (TMDI), dimer acid diisocyanate (DDI), etc., and compounds such as adducts, biurets, and isocyanurates in which the above compounds are associated. Examples include, but are not limited to. These compounds may be used singly or in combination of two or more.

By using a resin having a difunctional or more functional group as the resin used for the anchor layer of the present invention, the adhesion between the PET film base material, each component of the anchor layer, and the silicone adhesive layer is improved.

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, making it difficult to obtain the desired performance. When the content exceeds 30% by weight, the ratio of other components is relatively low, and the functions of the anchor layer of the present invention, such as heat resistance, adhesive strength with the base material and silicone adhesive layer, and oligomer derived from the PET film base material. The anti-migration performance of the components is lowered respectively. As a result, the adhesive film may peel off during handling of an 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 may be damaged. Adhesive residue may be left on the adherend, or the adherend may be contaminated with the oligomer.

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

Ethyl silicate hydrolyzate is obtained by hydrolyzing and polycondensing 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. You can get it by letting it. A commercially available ethyl silicate hydrolyzate may also 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 migration of the oligomer component derived from the PET film substrate cannot be obtained. If the content exceeds 30% by weight, the ratio of other components is relatively low, 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. In some cases, the adhesive layer may leave an adhesive residue on the adherend. In addition, the ability to prevent migration 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 for the ethylsilicate hydrolyzate to form a silicate polymer structure. In addition, when the anchor layer and adhesive layer are applied in the present invention, if the base material is electrically charged, uneven coating may occur. This can be dealt with by introducing a conductive material into the anchor layer, but since polystyrene sulfonic acid is also conductive and functions as the conductive material, 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 may not work as a catalyst, or the antistatic performance may become weak. When the content exceeds 30% by weight, the ratio of other components is relatively low, and the functions of the anchor layer of the present invention, such as heat resistance, adhesive strength with the base material and silicone adhesive layer, and oligomer derived from the PET film base material. The anti-migration performance of the components is lowered respectively. As a result, the adhesive film may peel off during handling of an 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 may be damaged. Adhesive residue may be left on the adherend, or the adherend may be contaminated with the oligomer.

(adhesive layer)
The adhesive layer of the adhesive film of the present invention is required to be reliably attached to an adherend and to be peelable without adhesive residue even after exposure to a high-temperature environment. As the adhesive layer for such applications, an addition reaction type silicone resin obtained by curing a silicone composition through an addition reaction with heat is particularly suitable for use 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, there is no generation of oligomers derived from the PET film base material even after exposure to high temperature environments, and no adhesive residue is left on the adherend. It can be an adhesive film that can be peeled off.

The addition reaction type silicone resin used in the adhesive layer of the present invention includes polyorganosiloxane and silicone resin having two or more vinyl groups in one molecule as a silicone composition, and an organohydro silicone resin having a SiH group as a curing agent. A material obtained by thermally curing through an addition reaction of GENpolysiloxane is preferably used. A suitable adhesive layer can be obtained by containing the above-mentioned polyorganosiloxane, the above-mentioned silicone resin, and the above-mentioned organohydrogenpolysiloxane having an SiH group as a silicone composition and thermally curing the silicone composition.

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

(Silicone resin adhesive layer)
As for the properties of the silicone resin used for the adhesive layer of the present invention, it is required that the silicone resin has rubber-like flexibility and that the surface of the adhesive layer conforms to the surface of the adherend. Furthermore, when peeling, it is required that the film can be easily peeled off with a small peeling force. In order to form an adhesive layer having a thickness of at least 5 μm and only by coating and heat treatment, the curing reaction of the silicone composition must be performed at a low temperature of 150° C. or less for a short period of time under an addition reaction catalyst such as a platinum catalyst. Diorganopolysiloxane having two or more vinyl groups per molecule, silicone resin, and SiH as a curing agent. It is preferred to use an addition reaction type liquid silicone composition which is heat cured by an addition reaction with an organohydrogenpolysiloxane having groups.

The diorganopolysiloxane having two or more vinyl groups per molecule includes a linear diorganopolysiloxane having vinyl groups only at both ends and a linear diorganopolysiloxane having vinyl groups at both ends and side chains. It is preferable to use at least one selected from organopolysiloxane, branched diorganopolysiloxane having vinyl groups only at the terminals, and branched diorganopolysiloxane having vinyl groups at terminals and side chains.

One form of these diorganopolysiloxanes is a linear diorganopolysiloxane having vinyl groups only at both ends, and is a compound represented by the following general formula (Chem. 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 type. Specific examples include alkyl groups such as methyl group, ethyl group and propyl group, and aryl groups such as phenyl group and tolyl group. , or monovalent hydrocarbon groups excluding the same or different 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. Preferably, at least 50 mol % of the diorganopolysiloxane is a methyl group, and this diorganopolysiloxane may be used alone or in combination of two or more.

Linear diorganopolysiloxane having vinyl groups at both ends and side chains is a compound in which part of R in the general formula (1) is a vinyl group. A branched polyorganosiloxane having vinyl groups only at the terminals is a compound represented by the general formula (2). A branched polyorganosiloxane having vinyl groups at its terminals and side chains is a compound in which part of R in the general formula (2) is a vinyl group.

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

The silicone resin used in the adhesive layer of the present invention includes M units (R ₃ SiO _1/2 : R is a monovalent organic group such as a methyl group and a phenyl group), D units (R ₂ SiO _2/2 ), A silicone resin composed of T units (RSiO _3/2 ) and Q units (SiO _4/2 ) can be used. It is preferable to contain a so-called conventionally known MQ type organopolysiloxane resin (hereinafter sometimes 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. A range of 0.10 to 15.00% by weight is particularly preferred. 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 off from the adherend, the thin film substrate or thin film sheet that is the adherend may be damaged.

In the combination of the diorganopolysiloxane and the silicone resin, the curing agent used for the curing reaction may be a known one, and examples of the curing agent include organohydrogenpolysiloxanes having SiH groups in the molecule. be done. Among them, it is particularly preferable to use a methylhydrogensiloxane-dimethylsiloxane copolymer. The methylhydrogensiloxane portion of the copolymer preferably has at least 3 silicon-bonded hydrogen atoms in one molecule, but from a practical standpoint, those having two ≡SiH bonds in the molecule are preferred. Preferably, the total amount is up to 50% by weight, the remainder containing at least 3 ≡SiH bonds in the molecule. As for the shape of the molecule, linear, branched, and cyclic ones can be used.

Further, the molar ratio (A)/(B) of the SiH groups (B) in the organohydrogenpolysiloxane to the vinyl groups (A) in the diorganopolysiloxane having vinyl groups is 1.0 to 2.0. is preferably blended so as to be in the range of If the molar ratio (A)/(B) is less than 1.0, the cured density may be insufficient, resulting in a decrease in cohesive strength and holding power. As a result, it becomes difficult to obtain a suitable adhesive force, and it becomes difficult to obtain a sufficient adhesive force due to the bonding between the hydroxyl group and the SiH group on the surface of the anchor.

The addition reaction catalyst used for the curing reaction is chloroplatinic acid, an alcohol solution of chloroplatinic acid, a reaction product of chloroplatinic acid and alcohol, a reaction product of chloroplatinic acid and an olefin compound, and chloroplatinic acid and vinyl group-containing siloxane. reaction products, platinum-olefin complexes, platinum-vinyl group-containing siloxane complexes, rhodium complexes, ruthenium complexes, and the like. Alternatively, these substances may be used by dissolving or dispersing them in a solvent such as isopropanol or toluene, silicone oil or the like. The cured adhesive layer becomes flexible like silicone rubber, and this flexibility facilitates adhesion to the adherend.

The addition amount of the addition reaction catalyst is preferably 5 to 2,000 ppm, more preferably 10 to 500 ppm, in terms of noble metal content per 100 parts by weight of the silicone composition. If it is less than 5 ppm, the curability may be lowered, the cured density may be lowered, and the holding power may be lowered.

Commercially available forms of the silicone composition according to the present invention include non-solvent type, solvent type, and emulsion type, and any type can be used. Among them, the non-solvent type is very advantageous in terms of safety, sanitation and air pollution because it does not use a solvent. However, even if it is a non-solvent type, aromatic hydrocarbon solvents such as toluene and xylene, and fats such as hexane, heptane, octane, and isoparaffin may be used to adjust the viscosity to obtain the desired film thickness. 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, and mixed solvents thereof. is used.

The amount of the solvent added is preferably 20 to 1,000 parts by weight, particularly 25 to 900 parts by weight, per 100 parts by weight of the silicone composition. If the amount is less than 20 parts by weight, the adhesion between the adhesive layer and the anchor layer may decrease and the adhesive layer may peel off. During the period from later to curing, the applied adhesive layer partially flows, and the smoothness of the surface of the adhesive layer is reduced.

The adhesive layer of the present invention is required to have rubber-like flexibility and follow the irregularities of the surface of the adherend to ensure adhesion when adhered to the adherend. And, for example, when used as a support film for manufacturing the above parts, the film thickness of the adhesive layer is preferably at least 5 μm or more, usually 10 to 100 μm, in order to ensure a shearing force in the direction of the adhesion surface of the adhesive layer to the adherend. , 20 to 50 μm. If the thickness is less than 5 μm, the shearing force in the direction of the adhesion surface of the protective member to the adherend cannot be ensured, and the adhesive film is easily peeled off from the adherend, especially during long-term application. Moreover, when the thickness of the adhesive layer exceeds 100 μm, the amount of the resin constituting the adhesive layer used increases, resulting in 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 whose viscosity is adjusted, or dispersing the resin constituting the adhesive layer in water and applying it. A known method such as a method can be used. As the organic solvent, a general organic solvent can be used without particular limitation. Examples include, but are not limited to, organic solvents for adjusting the viscosity described above.

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

(separator)
In the present invention, it is preferable to use a separator made of a plastic film attached to the surface of the adhesive layer for the purpose of preventing contamination and adhesion of foreign matter to the surface of the adhesive layer and improving the handling of the adhesive film. The separator is made of a highly releasable plastic film, and if desired, a release agent is formed on the surface of the plastic film.

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In addition, "parts" in each example indicate parts by weight unless otherwise specified.

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

Ethyl silicate: Silicate 40 manufactured by Tama Chemical Industry Co., Ltd. 25.0 parts by weight Isopropyl alcohol (IPA) 72.0 parts by weight Water 2.0 parts by weight
Hydrochloric acid 1.0 parts by weight

(Examples 1 to 11, Comparative Examples 1 to 10)
Using a PET film with a thickness of 50 μm as a base material, one side was subjected to corona discharge treatment, and mixed according to the formulations described in Examples 1 to 11 and Comparative Examples 1 to 10 in Tables 2 and 3. Each anchor layer coating liquid was adjusted so that the thickness after drying was each value shown in Table 2, and was applied to the corona discharge-treated surface of the substrate, and the organic solvent was removed at 100°C for 2 minutes. Then, each anchor layer was formed by heating in order that the ethyl silicate hydrolyzate would have a siloxane polymer structure. Each of the adhesive layer coating solutions shown in Table 1 below was applied thereon so that the thickness after drying would be 15 μm, and then dried by heating at 100° C. for 2 minutes to remove the organic solvent. The adhesive layer was formed by heating for 1 second to cure the coating liquid, and adhesive films of Examples 1 to 11 and Comparative Examples 1 to 10 were produced. Each adhesive film thus prepared was cut to a width of 25 mm, the adhesive layer of each adhesive film was attached to a glass plate having a thickness of 1 mm, heated at 180° C. for 2 minutes, cooled to room temperature, and attached to the glass plate. A laminate was prepared by sticking the adhesive film.

単位：重量部

Unit: part by weight

Tables 2 and 3 show the material composition ratios and evaluation results of each example and comparative example, and each evaluation method is shown below.

(Evaluation method)

(Adhesion evaluation between base material and anchor layer)
In the films having the anchor layers of Examples 1 to 11 and Comparative Examples 1 to 10, the adhesion between the substrate and the anchor layer was visually observed by rubbing the anchor layer with a finger, and evaluated according to the following criteria.
A: No detachment from the base material after 50 finger rubbings.
○: Detachment from the substrate after rubbing with fingers 10 times or more and less than 50 times.
x: Falling off from the base material after less than 10 finger rubbings.

(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 to visually observe the adhesiveness between the anchor layer and the adhesive layer, and evaluated according to the following criteria.
A: No detachment from the base material after 15 finger rubbings.
◯: Detachment from the base material after finger rubbing 5 times or more and less than 15 times.
x: Less than 5 rubbings with a finger, falling off from the base material.

(Oligomer migration prevention property evaluation)
In the laminates of the glass plates and the adhesive films prepared in Examples 1 to 11 and Comparative Examples 1 to 10, the haze values of the laminates before and after heating at 180° C. for 2 minutes were measured by a method in accordance with JIS-K7136. The difference was evaluated according to the following criteria, and the oligomer migration prevention property was evaluated.
◯: Difference in haze value before and after heating is less than 1.0%.
Δ: 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)
In the laminates of the glass plate and each adhesive film prepared in Examples 1 to 11 and Comparative Examples 1 to 10, when the adhesive film was peeled at a speed of 300 mm/min at 180°, the anchor of the adhesive film The peelability was evaluated by a method of visually confirming the occurrence of cracks in the layer.
Evaluation criteria ◯: The anchor layer was not cracked during peeling and could be peeled off easily.
x: A crack occurred in the anchor layer at the time of peeling.

(Evaluation of heat resistance and adhesive residue resistance of adhesive layer)
In the laminates of the glass plate and each adhesive film prepared in Examples 1 to 11 and Comparative Examples 1 to 10, when the adhesive film was peeled at 180° at a speed of 300 mm / min, after peeling the adhesive film Adhesion of the adhesive layer to the glass plate was visually confirmed to evaluate the amount of adhesive residue.
Evaluation Criteria ◯: No adhesion of the adhesive layer to the glass plate.
x: Adhesion of the adhesive layer to the glass plate is observed.

Claims (4)

An adhesive 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 comprises at least vinyl group-containing polyorganosiloxane and an organohydrogen polyimide having SiH groups as a curing agent. The anchor layer comprises 40 to 84 % by weight of colloidal silica, 10 to 30% by weight of resin, and ethyl silicate hydration. An adhesive film containing 5 to 30% by weight of a decomposition product and 1 to 30% by weight of polystyrene sulfonic acid. 2. The adhesive film according to claim 1, wherein the resin contained in the anchor layer is any one selected from polyester resin, urethane resin, and acrylic urethane resin. 3. The adhesive film according to claim 1, wherein the vinyl group-containing polyorganosiloxane is vinyl group-containing polydimethylsiloxane. The adhesive film according to any one of claims 1 to 3, wherein the anchor layer has a thickness of 0.05 to 3.00 µm.