JP2009233953A - Biodegradable release film and adhesive film using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable release film which is excellent in adhesion between a release layer and a polylactic film and also in flatness. <P>SOLUTION: The biodegradable release film includes a polylactic film, and a release layer formed thereon, the release layer being formed of a releasable composition including the following (A)-(D): (A) a vinyl group-containing organopolysiloxane having at least two vinyl groups directly bonded to silicon atom in one molecule; (B) an organohydrogen polysiloxane having at least two hydrogen atoms directly bonded to silicon atom in one molecule; (C) an organosiloxane having, in one molecule, at least one group selected from an acrylic group, a methacrylic group and an epoxy group, and at least one hydrogen atom, which are respectively directly connected to silicon atom, and at least one alkoxysilyl group connected to silicon atom through an alkylene group; and (D) an additive reaction catalyst. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a biodegradable release film.

  In recent years, the disposal of plastics has been widely taken up as a social problem. The adhesive film (Patent Document 1), which is widely used at present, is not an exception and has a problem of disposal, and is incinerated after use or discarded in the soil. Incineration produces toxic gases and carbon dioxide, which causes global warming. In the case of disposal in the soil, it remains indefinitely without being decomposed, causing soil contamination. Under such circumstances, there is a technology that uses a biodegradable film as an adhesive film substrate to solve the disposal problem after use (Patent Document 2).

  Moreover, there exists a technique using a biodegradable film also about the release film used for an adhesive film (patent document 3). Since the release film is peeled off and discarded during use, it is effective to impart biodegradability. Such a release film has a structure having a release layer on a biodegradable film typified by polylactic acid.

  However, a polylactic acid film mainly used as a biodegradable film tends to have poor adhesion. The problem of adhesiveness is the same for the release film as in Patent Document 3, and the adhesiveness between the polylactic acid film and the release layer is not sufficient, and the release layer adheres when the release film is peeled off. There is a problem in that the transfer to the layer adversely affects the performance of the adhesive layer.

  In addition, the polylactic acid film is inferior in heat resistance, and when a release agent is applied and dried to form a release layer, the film base material is softened and the flatness of the film is liable to be impaired.

JP-A-6-278238 JP 2005-290311 A JP 2007-90652 A

  Accordingly, an object of the present invention is to provide a biodegradable release film that is excellent in adhesiveness with a polylactic acid film and excellent in flatness.

The biodegradable release film of the present invention that solves the above problem has a release layer formed on a polylactic acid film from a release composition containing the following (A) to (D). It is a feature.
(A) Vinyl group-containing organopolysiloxane having at least two vinyl groups directly bonded to silicon atoms in one molecule (B) Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms in one molecule ( C) At least one alkoxysilyl group bonded via a hydrogen atom and an alkylene group, any one selected from an acrylic group, a methacrylic group, and an epoxy group, each directly bonded to a silicon atom in one molecule Organopolysiloxane (D) addition reaction catalyst

  In the biodegradable release film of the present invention, preferably, the polylactic acid film is at least a first layer composed of a polylactic acid-based polymer having crystallinity, and is more crystalline than the first layer. The second layer is composed of a low polylactic acid polymer, and the second layer and the release layer are formed to face each other.

  Further, the adhesive film of the present invention is an adhesive film having an adhesive layer and a release film in this order on a substrate, wherein the release film is the biodegradable release film according to claim 1 or 2, The release layer and the adhesive layer are bonded together so as to face each other.

  The biodegradable release film of the present invention is excellent in adhesion between the release layer and the polylactic acid film and has excellent flatness because the release layer is formed from a specific release composition. A biodegradable release film can be obtained.

  Since the adhesive film of the present invention has excellent adhesion between the release layer and the polylactic acid film, the release layer can be prevented from being transferred to the adhesive layer side when the release film is peeled off. .

The biodegradable release film of the present invention is characterized in that it has a release layer formed from a release composition containing the following (A) to (D) on a polylactic acid film. is there.
(A) Vinyl group-containing organopolysiloxane having at least two vinyl groups directly bonded to silicon atoms in one molecule (B) Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms in one molecule ( C) At least one alkoxysilyl group bonded via a hydrogen atom and an alkylene group, any one selected from an acrylic group, a methacrylic group, and an epoxy group, each directly bonded to a silicon atom in one molecule Hereinafter, embodiments of the biodegradable release film of the present invention will be described.

  The polylactic acid film is mainly composed of a polylactic acid polymer. The polylactic acid polymer is a polymer formed by condensation polymerization of a monomer containing lactic acid as a main component. Lactic acid includes two types of optical isomers, L-lactic acid and D-lactic acid, and the crystallinity differs depending on the proportion of these two structural units. For example, a random copolymer having a ratio of L-lactic acid to D-lactic acid of approximately 80:20 to 20:80 has no crystallinity, and becomes a transparent amorphous polymer that softens near a glass transition point of 60 ° C. On the other hand, a random copolymer having a ratio of L-lactic acid to D-lactic acid of approximately 100: 0 to 80:20 or 20:80 to 0: 100 has crystallinity. The crystallinity is determined by the ratio of L-lactic acid and D-lactic acid, but the glass transition point of this copolymer is a polymer of about 60 ° C. as described above. This polymer becomes an amorphous material with excellent transparency by being rapidly cooled after melt extrusion, and becomes a crystalline material by slowly cooling. For example, a homopolymer composed of only L-lactic acid or only D-lactic acid is a semicrystalline polymer having a melting point of 180 ° C. or higher.

  It is preferable that at least a part of the polylactic acid-based polymer constituting the polylactic acid film has crystallinity in order to improve the coating property of the biodegradable release film.

  The polylactic acid film may be composed of two or more layers composed of polylactic acid polymers having different crystallinity. For example, the polylactic acid film includes at least a first layer composed of a polylactic acid-based polymer having crystallinity, and a polylactic acid-based polymer having lower crystallinity than the first layer (not including a polylactic acid-based polymer). ) You may make it consist of a 2nd layer comprised from a polylactic acid-type polymer. The lower the crystallinity of the polylactic acid-based polymer, the better the adhesion with a release layer described later. Therefore, the polylactic acid film includes at least a first layer composed of a polylactic acid polymer having crystallinity and a second layer composed of a polylactic acid polymer having lower crystallinity than the first layer (crystallinity). And a release film having sufficient film property and adhesiveness by forming the second layer and a release layer to be described later so as to face each other. Can do.

  The polylactic acid film is preferably biaxially stretched. As a biaxial stretching method, a sheet or cylindrical material extruded from a T die, an I die, a round die or the like is rapidly cooled by a cooling cast roll, water, compressed air, or the like, and solidified in a state close to an amorphous state. Examples of the biaxial stretching method include a roll method, a tenter method, and a tubular method.

  The thickness of the polylactic acid film is preferably 10 to 100 μm, and more preferably 15 to 80 μm. When the polylactic acid film is composed of two or more layers, the thickness of the layer having little crystallinity (or no crystallinity) is preferably 2 μm or more, more preferably 5 μm or more, and further preferably 10 μm or more.

The release layer is formed from a releasable composition containing the following (A) to (D).
(A) Vinyl group-containing organopolysiloxane having at least two vinyl groups directly bonded to silicon atoms in one molecule (B) Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms in one molecule ( C) At least one alkoxysilyl group bonded via a hydrogen atom and an alkylene group, any one selected from an acrylic group, a methacrylic group and an epoxy group, each directly bonded to a silicon atom in one molecule Organopolysiloxane (D) addition reaction catalyst

  The vinyl group-containing organopolysiloxane (A) has at least two vinyl groups bonded to silicon atoms in one molecule.

  In this case, the organic group other than the vinyl group includes an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group and a hexyl group, an aryl group such as a phenyl group, a β-phenylethyl group, and a β-phenylpropyl group. Substituted hydrocarbons such as chloromethyl groups and 3,3,3-trifluoropropyl groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine atoms and chlorine atoms Group. Among these, a methyl group that is easy to synthesize and can exhibit excellent releasability with respect to the adhesive substance is preferable.

  The organopolysiloxane (A) may be linear or branched, or a mixture thereof. Moreover, it is preferable that the molecular chain terminal of (A) is a vinyl group from the viewpoint of curability of the releasable composition, and in particular, from the viewpoint of adhesiveness to the polylactic acid film, a vinyl group is added to the molecular chain terminal. It is preferable to have one. As such an organopolysiloxane containing three vinyl groups at its terminal, those represented by the following formula (1) are suitable.

Here, R ¹ is a substituted or unsubstituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond, preferably having 1 to 12 carbon atoms, particularly 1 to 3 carbon atoms other than the vinyl group described above. What was illustrated as an organic group is mention | raise | lifted. In addition, m is 0-100, Especially preferably, it is 0-20, n is 100-8000, Most preferably, it is an integer of 200-500.

  The viscosity of the organopolysiloxane (A) at 25 ° C. is not particularly limited, but is preferably 60 cs (centistokes) or more from the viewpoint of curability of the release composition. .

  Next, the organohydrogenpolysiloxane of component (B) contains hydrogen atoms directly bonded to at least two silicon atoms in the molecule, and examples of organic groups other than hydrogen atoms directly bonded to silicon atoms include ( Examples thereof include those exemplified for the organopolysiloxane of component A).

  Specific examples of the component (B) include α, ω-bis (dimethylhydrogensilyl) polydimethylsiloxane, α, ω-bis (trimethylsilyl) polymethylhydrogenpolysiloxane, α, ω-bis (trimethylsilyl) poly ( Methylhydrogen) (dimethyl) siloxane copolymer and the like.

  Moreover, the molecular shape of (B) component may be linear, branched or cyclic, and the viscosity at 25 ° C. is preferably 10 to 50 cs.

  (B) The compounding quantity of a component is 0.1-20 weight part with respect to 100 weight part of (A) component, It is preferable to set it as 2-15 weight part especially. By making it 0.1 parts by weight or more, it is possible to improve the curability of the mold release composition, and by making it 20 parts by weight or less, it is possible to prevent the release properties from becoming unstable. it can. In addition, the molar ratio of HSi≡ to the vinyl group of the component (A) can be adjusted according to the purpose in the range of usually 0.5 to 10.

  The component (C) contains at least one acryl group, methacryl group or epoxy group directly bonded to a silicon atom in each molecule, a hydrogen atom and an alkoxysilyl group bonded via an alkylene group. Examples thereof include a cyclic siloxane represented by the following formula (2) and a linear siloxane represented by the following formula (3).

In formulas (2) and (3), R ¹ is a substituted or unsubstituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond, R ² is an acrylic group-containing alkylene group, a methacryl group-containing alkylene group, or an epoxy group An alkylene group, R ³ represents an alkoxysilyl group-containing alkylene group, t and x represent an integer of 0 or more, and s, u, v, w, y, and z are integers of 1 or more.

Wherein, R ¹ is the same as R ¹ in the formula (1), also the acrylic group as the organic group of a methacrylic group, an epoxy group, alkoxysilyl group-containing organic group, an oxygen atom or a sulfur atom interposed The alkylene group which may be sufficient can be mention | raise | lifted, In this case, one part or all part of the hydrogen atom of this alkylene group may be substituted by the hydroxyl group. In addition, as an alkylene group in this case, a C1-C8, especially 2-6 thing is preferable. Moreover, as an alkoxy group of an alkoxy silyl group, a C1-C5 thing is suitable. The alkoxysilyl group is preferably a trialkoxysilyl group, but may be an alkyldialkoxysilyl group, a dialkylalkoxysilyl group, etc. (note that the alkyl group preferably has 1 to 5 carbon atoms).

  Examples of the acrylic group, methacryl group, epoxy group, and alkoxysilyl group-containing alkylene group include the following.

  In the above formula (2), t is an integer of 0 or more, s, u, v are integers of 1 or more, and preferably satisfies 3 ≦ s + t + u + v ≦ 8. Moreover, in said formula (3), x is an integer greater than or equal to 0, w, y, z is an integer greater than or equal to 1, and it is preferable to satisfy | fill 3 <= w + x + y + z <= 40.

  Component (C) is blended in an amount of 0.1 to 20 parts by weight, particularly 1 to 10 parts by weight per 100 parts by weight of component (A). By making the component (C) 0.1 parts by weight or more, the adhesiveness with the polylactic acid film can be improved, and by making it 20 parts by weight or less, the release property is prevented from becoming unstable. can do.

  The addition reaction catalyst for component (D) is a catalyst for curing the silicone rubber compound by the addition reaction of the vinyl group of the organopolysiloxane of component (A) and the hydrosilyl group of the organohydrogenpolysiloxane of component (B). . As this addition reaction catalyst, a platinum-based catalyst including platinum alone, a platinum compound and a platinum complex is preferably used. Examples of the platinum-based catalyst include chloroplatinic acid such as platinum chloride primary acid and platinum chloride secondary acid, alcohol compounds of chloroplatinic acid, aldehyde compounds, ether compounds, and complexes with various olefins.

  The addition amount of the addition reaction catalyst is preferably 0.015 to 0.1 part by weight, particularly 0.02 to 0.05 part by weight, based on 100 parts by weight of component (A). The blending amount is determined according to reactivity, economy, and a desired curing rate. By setting the addition reaction catalyst content to 0.015 parts by weight or more, the releasable composition can be cured at a low temperature and in a short time, and the flatness of the polylactic acid film can be maintained.

  The releasable composition described above can be obtained by uniformly mixing predetermined amounts of the above components (A) to (D). If necessary, inorganic fillers such as silica and colloidal silica, pigments, reaction control agents A photopolymerization initiator or the like can be added.

In actual use of the above-described release composition, for example, the composition prepared as described above is diluted with an organic solvent such as toluene or xylene as necessary, and then 0.05 to 0.5% on the polylactic acid film. A release layer that is coated at a rate of 5 g / m ² , is heated at 70 to 170 ° C. for 5 to 60 seconds and / or is irradiated with ultraviolet rays, and has excellent adhesiveness with a polylactic acid film and excellent release properties. Can be obtained.

  Next, the adhesive film of the present invention will be described. The adhesive film of the present invention is an adhesive film having an adhesive layer and a release film in this order on a substrate, wherein the release film is the biodegradable release film according to claim 1 or 2, and the biodegradable The release layer of the release film and the adhesive layer are bonded so as to face each other.

  Base materials include polyester, ABS (acrylonitrile-butadiene-styrene), polystyrene, polycarbonate, acrylic, liquid crystal polymer (LCP), polyolefin, cellulose resin, polysulfone, polyphenylene sulfide, polyethersulfone, polyetheretherketone, polyimide, poly Examples thereof include plastic films such as lactic acid, paper, and fibers. You may form functional layers, such as a layer which improves printability, in the surface on the opposite side to the contact bonding layer of a base material.

  The adhesive layer is composed of an acrylic pressure sensitive adhesive, a rubber pressure sensitive adhesive, a polyester pressure sensitive adhesive, or the like. Among these, acrylic pressure-sensitive adhesives are preferably used because of excellent transparency and processability.

  The adhesive film of the present invention is obtained by laminating an adhesive layer formed on a substrate and a separately prepared biodegradable release film of the present invention so that the adhesive layer and the release layer face each other. Can be manufactured. Since such an adhesive film has good peelability between the adhesive layer and the release layer, and the adhesiveness between the release layer constituting the release film and the polylactic acid film is good, the release film It is possible to prevent the release layer from being transferred to the adhesive layer when peeling.

  The following examples further illustrate the present invention. “Parts” and “%” are based on weight unless otherwise specified.

1. Synthesis of Component (C) 45.6 g of allyl glycidyl ether, 14.8 g of vinyltrimethoxysilane, and 0.1 g of 2% butanol solution of chloroplatinic acid were charged in a glass flask and heated to 70 ° C. while stirring. 12.1 g of methyl hydrogen polysiloxane represented by the formula (4) was added dropwise over 3 hours.

  This solution is heated at 80 ° C. for 5 hours, then cooled and treated with activated carbon to obtain a reaction mixed solution, and then the solvent and low-boiling substances are removed from the reaction mixed solution under reduced pressure by the following formula. 65.2 g of a linear organopolysiloxane having a hydrogen atom directly bonded to a silicon atom, an epoxy group, and an alkoxysilyl group, each represented by (5), was obtained.

2. Preparation of biodegradable release film [Example 1]
(A) 100 g of molecular chain-terminated trivinyl-blocked dimethylpolysiloxane having a viscosity of 1000 cs at 25 ° C. and (B) α, ω-bis (trimethylsilyl) polymethyl having a viscosity of 40 cs. 7 g of hydrogen polysiloxane, (C) 3 g of the compound of the above formula (5) obtained in the above synthesis example, (D) 4 g of chloroplatinic acid-olefin complex (0.02 g as platinum amount), 1.0 g of acetylene alcohol Mixing was performed until it became uniform to obtain a releasable composition A.

  Next, a polylactic acid film B (Ecology Rouge SC: Mitsubishi Plastics) having a second layer made of a polylactic acid polymer having lower crystallinity than the first layer on both sides of the first layer made of crystalline polylactic acid polymer. The above-mentioned release composition A was applied to one side of the company, the thickness of the first layer: 90 μm, the thickness of the second layer: 5 μm each, so that the thickness after drying was 0.3 μm, The film was dried at 30 ° C. for 30 seconds, and cured by irradiating ultraviolet rays for 1 to 2 seconds with a high-pressure mercury lamp to obtain a biodegradable release film of Example 1.

  Next, an adhesive layer coating solution obtained by diluting an acrylic pressure-sensitive adhesive (SK Dyne 1491H: Soken Chemical Co., Ltd.) with a solvent on one surface of the polylactic acid film B (Ecology Rouge SC: Mitsubishi Plastics Co., Ltd.) at 60 ° C. It dried for minutes and obtained the adhesive sheet C.

  Subsequently, the release layer side of the biodegradable release film and the adhesive layer side of the adhesive sheet C were bonded together to obtain an adhesive film of Example 1.

[Example 2]
The polylactic acid film B of Example 1 is a polylactic acid film (Ecologe SA: Mitsubishi Plastics) comprising a single layer of a first layer (corresponding to the first layer of the polylactic acid film B) made of a crystalline polylactic acid polymer. The biodegradable release film and adhesive film of Example 2 were obtained in the same manner as in Example 1 except that the thickness was changed to 100 μm.

[Comparative Example 1]
A biodegradable release film and an adhesive film of Comparative Example 1 were obtained in the same manner as in Example 2 except that the component (A) was removed from the releasable composition A.

[Comparative Example 2]
A biodegradable release film and an adhesive film of Comparative Example 2 were obtained in the same manner as in Example 2 except that the component (B) was removed from the release composition A.

[Comparative Example 3]
A biodegradable release film and an adhesive film of Comparative Example 3 were obtained in the same manner as in Example 2 except that the component (C) was removed from the releasable composition A.

[Comparative Example 4]
A biodegradable release film and an adhesive film of Comparative Example 4 were obtained in the same manner as Comparative Example 1 except that the drying temperature of Comparative Example 1 was 120 ° C.

  The following items were evaluated for the biodegradable release films and adhesive films obtained in Examples 1 and 2 and Comparative Examples 1 to 4. The results are shown in Table 1.

(1) Adhesiveness of release layer The adhesiveness between the release layer and the polylactic acid film of the biodegradable release films obtained in Examples 1 and 2 and Comparative Examples 1 to 4 was determined using a silicone pressure-sensitive adhesive layer. Evaluation was performed by a cross-cut tape method (JIS K5600-5-6: 1999) using a held polyester tape (Sliontec Corp., No. 6266). As a result of the peel test by the cross-cut tape method, “◎” indicates that the cross-cut portion did not peel at all, “○” indicates that a part of the cross-cut portion peeled but the peel area was less than 10%, “○” The case where the area of the part was peeled off by 10% or more and less than 20% was designated as “Δ”, and the case where the area of the grid part was peeled off by 20% or more was designated as “X”.

(2) Degree of curing of release layer After the release layer of the biodegradable release films obtained in Examples 1 and 2 and Comparative Examples 1 to 4 was rubbed with the finger 10 times, the coating film It was evaluated by the presence or absence of occurrence of cloudiness or peeling of the coating film. The case where the coating film was not fogged or peeled at all was indicated as “◎”, the coating film which was clouded but not accompanied by coating film peeling was indicated as “◯”, and the coating film peeling occurred as “X”.

(3) Planarity of biodegradable release film The appearance of the biodegradable release films obtained in Examples 1 and 2 and Comparative Examples 1 to 4 was visually evaluated. “O” means that the film has irregularities and causes trouble when the adhesive film is produced.

(4) Release property of adhesive film The biodegradable release film is peeled from the adhesive films obtained in Examples 1 and 2 and Comparative Examples 1 to 4, and the transfer state of the release layer to the adhesive layer is determined. Visual evaluation was made. "◎" indicates that the release layer is not transferred, and slight transfer of the release layer is observed, but "○" indicates that there is little effect on adhesive strength and does not interfere with use. In addition, the case where the influence on the adhesive force was great and the use was hindered, or the case where the adhesive layer could not be peeled off from the release layer and the adhesive layer remained even on the release layer side was rated as “x”.

  The biodegradable release films of Examples 1 and 2 are, on a polylactic acid film, (A) a vinyl group-containing organopolysiloxane having at least two vinyl groups directly bonded to silicon atoms in one molecule, (B) 1 Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms in the molecule, (C) Any one selected from an acrylic group, a methacrylic group, and an epoxy group each directly bonded to a silicon atom in one molecule A release layer formed from a release composition comprising an organopolysiloxane having at least one hydrogen atom and an alkoxysilyl group bonded via an alkylene group, and (D) an addition reaction catalyst Therefore, the adhesion between the polylactic acid film and the release layer was excellent.

  The biodegradable release film of Example 1 is composed of a first layer composed of a polylactic acid polymer having crystallinity and a polylactic acid polymer having lower crystallinity than the first layer. Since a polylactic acid film composed of the second layer is used, the adhesiveness with the release layer was particularly excellent.

  And since the adhesive film of Example 1, 2 had favorable adhesiveness of a mold release layer and a polylactic acid film, it was able to peel between an adhesive layer and a mold release layer. Moreover, since the flatness of the polylactic acid film was good, the unevenness of the polylactic acid film was not transferred to the adhesive layer as in Comparative Example 4.

  The biodegradable release film of Comparative Example 1 is obtained by removing the component (A) from the components (A) to (D). Therefore, the adhesiveness between the release layer and the polylactic acid film was inferior. Moreover, since the adhesive film of Comparative Example 1 does not contain the component (A), if the adhesive film is peeled between the adhesive layer and the release layer, the adhesive layer remains slightly on the release layer side. .

  The biodegradable release film of Comparative Example 2 is obtained by removing the component (B) from the components (A) to (D). Therefore, the curability of the release layer is inferior, and the adhesion between the release layer and the polylactic acid film is poor. Moreover, since the adhesive film of Comparative Example 2 did not contain the component (B), when it was peeled between the adhesive layer and the release layer, transfer of the release layer was seen and the adhesive strength was poor. .

  The biodegradable release film of Comparative Example 3 is obtained by removing the component (C) from the components (A) to (D). Therefore, although the release layer is cured, the adhesiveness between the release layer and the polylactic acid film is inferior. In addition, since the adhesive film of Comparative Example 3 does not contain the component (C), if it is peeled between the adhesive layer and the release layer, the release layer is peeled off from the polylactic acid film and transferred to the adhesive layer. The adhesive strength was inferior.

The biodegradable release film of Comparative Example 4 was cured at 120 ° C. during the formation of a coating film of the release composition except for the component (A), as in Comparative Example 1. For this reason, the polylactic acid film is deformed by heat, which causes troubles in making the adhesive film. Moreover, although the adhesive film of Comparative Example 4 could be peeled between the adhesive layer and the release layer, the uneven pattern of the polylactic acid film deformed by heat was transferred to the adhesive layer. When the adhesive layer is bonded to the adherend, an uneven pattern of the adhesive layer is generated.

Claims (3)

A biodegradable release film comprising a release layer formed from a release composition containing the following (A) to (D) on a polylactic acid film.
(A) Vinyl group-containing organopolysiloxane having at least two vinyl groups directly bonded to silicon atoms in one molecule (B) Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms in one molecule ( C) At least one alkoxysilyl group bonded via a hydrogen atom and an alkylene group, any one selected from an acrylic group, a methacrylic group, and an epoxy group, each directly bonded to a silicon atom in one molecule Organopolysiloxane (D) addition reaction catalyst   The polylactic acid film comprises at least a first layer composed of a polylactic acid polymer having crystallinity and a second layer composed of a polylactic acid polymer having lower crystallinity than the first layer. The biodegradable release film according to claim 1, wherein the second layer and the release layer are formed to face each other. An adhesive film having an adhesive layer and a release film in this order on a substrate, wherein the release film is the biodegradable release film according to claim 1 or 2, and the release layer and the adhesive layer An adhesive film characterized by being bonded so as to face each other.