Two-pack curable coating agent for demolding sheet, and demolding sheet

Abstract

The objective of the present invention is to provide a two-pack curable coating agent for a demolding sheet, the two-pack curable coating agent being capable of forming a demolding layer that is excellent in both demolding characteristics and extensibility. The present invention is a two-pack curable coating agent for a demolding sheet, the two-pack curable coating agent being characterized in that: a main agent containing a polyol (P) and a curing agent containing polyisocyanate (I) are contained; and the polyol (P) contains a (meth)acrylic polyol (A) containing more than 0 mass% but less than 12 mass% of structural unit (S1) having a siloxane bond represented by formula (1), and a (meth)acrylic polyol (B) containing 12-30 mass% of structural unit (S1) having a siloxane bond represented by formula (1).

Description

Two-component curing coating agent for release sheets, and release sheets

[0001] The present invention relates to a two-component curing coating agent for a release sheet, and a release sheet.

[0002] Conventionally, semiconductor chips are encapsulated in a semiconductor encapsulation process with an encapsulating resin to form a semiconductor package, which is then mounted on an electronic substrate. The semiconductor package protects the semiconductor chip from external shocks, heat, and humidity.

[0003] In the semiconductor encapsulation process, a semiconductor package is obtained by, for example, curing an encapsulation resin in a mold in which a semiconductor chip is placed. Thermosetting resins such as epoxy resins are generally used as the encapsulation resin.

[0004] To improve the releasability of the semiconductor package from the mold, a release sheet is placed on the inner surface of the mold beforehand during the semiconductor encapsulation process. After the release sheet is placed on the mold, it is attached to the inner surface of the mold by vacuuming or the like, and then the semiconductor chip is encapsulated. The use of the release sheet prevents contamination of the mold by the encapsulation resin and makes it easy to remove the semiconductor package from the mold.

[0005] Conventionally, a single-layer sheet made of ETFE (ethylene-tetrafluoroethylene copolymer) has been used as a release sheet for semiconductor packages because of its excellent heat resistance and releasability. However, ETFE is expensive, and the release sheet is discarded after each semiconductor encapsulation process. Therefore, there is a need for a cheaper release sheet.

[0006] Therefore, Patent Document 1 discloses a laminated release sheet having a support layer and a release layer laminated and integrated on one surface of the support layer. The support layer is made of a synthetic resin such as polybutylene terephthalate (PBT), which imparts heat resistance to the release sheet. In addition, the release layer is made of a cured film of a urethane acrylate coating agent (release agent).

[0007] International Publication No. 2014 / 203872

[0008] However, in conventional laminated release sheets, the release layer has insufficient releasability, and therefore, after the semiconductor encapsulation process is completed, the semiconductor package may not be easily peeled off from the release sheet.

[0009] On the other hand, simply improving the releasability of the release layer may result in a decrease in the extensibility of the release layer. Therefore, when the inner surface of the mold has a complex shape or a large uneven shape with large differences in height, the release sheet may not be able to sufficiently conform to the shape of the inner surface of the mold and may tear. When a tear occurs in the release sheet, the sealing resin flows out from the torn part and contaminates the mold.

[0010] As described above, with conventional release sheets, it is difficult to improve the releasability while reducing the decrease in the extensibility of the release layer, and there is a need for a release sheet having a release layer that achieves both releasability and extensibility.

[0011] Therefore, an object of the present invention is to provide a two-component curing coating agent for release sheets that can form a release layer that is excellent in both releasability and elongation, and a release sheet having a release layer that is a cured film of the two-component curing coating agent for release sheets.

[0012] The present invention solves the above problems by providing a two-component curing coating agent for release sheets, which comprises a base agent containing a polyol (P) and a curing agent containing a polyisocyanate (I), wherein the polyol (P) comprises: a (meth)acrylic polyol (A) having a content of structural units (S1) having siloxane bonds represented by the following formula (1) that is greater than 0 mass% and less than 12 mass%, and a (meth)acrylic polyol (B) having a content of structural units (S1) having siloxane bonds represented by the following formula (1) that is 12 mass% or more and 30 mass% or less.

[0013] (In formula (1), R 1 and R 2 each independently represents a hydrogen atom or a monovalent hydrocarbon group, and * represents a bond.

[0014] Furthermore, the present invention solves the above problems by providing a release sheet having a support layer and a release layer that is laminated and integrated on one surface of the support layer and is a cured film of the two-component curing coating agent for release sheets.

[0015] According to the present invention, it is possible to provide a two-component curing coating agent for a release sheet that can form a release layer that is excellent in both releasability and elongation, and a release sheet having a release layer that is a cured film of the two-component curing coating agent for a release sheet.

[0016] FIG. 2 is a diagram illustrating a contact angle in the present invention.

[0017] [Two-component curing coating agent for release sheets] The two-component curing coating agent for release sheets of the present invention comprises a base agent containing a polyol (P) and a curing agent containing a polyisocyanate (I), wherein the polyol (P) comprises: a (meth)acrylic polyol (A) having a content of structural units (S1) having siloxane bonds represented by the following formula (1) that is greater than 0 mass% and less than 12 mass%, and a (meth)acrylic polyol (B) having a content of structural units (S1) having siloxane bonds represented by the following formula (1) that is 12 mass% or more and 30 mass% or less.

[0018] (In formula (1), R 1 and R 2 each independently represents a hydrogen atom or a monovalent hydrocarbon group, and * represents a bond (single bond).

[0019] The (meth)acrylic polyol (A) and the (meth)acrylic polyol (B) each contain a siloxane bond (≡Si—O—). Specifically, the (meth)acrylic polyol (A) contains a structural unit (S1) having a siloxane bond represented by the above formula (1). The (meth)acrylic polyol (B) also contains a structural unit (S1) having a siloxane bond represented by the above formula (1). Note that the "structural unit (S1) having a siloxane bond represented by the above formula (1)" may be simply referred to as the "structural unit (S1)."

[0020] The structural unit (S1) contained in the (meth)acrylic polyol (A) and the structural unit (S1) contained in the (meth)acrylic polyol (B) may be the same or different from each other.

[0021] In the above formula (1), R 1 and R 2 are each independently a hydrogen atom or a monovalent hydrocarbon group. 1 and R 2 may be the same or different, but are preferably the same. Examples of the monovalent hydrocarbon group include an alkyl group, a cycloalkyl group, and an aryl group. Of these, an alkyl group is preferred.

[0022] The number of carbon atoms in the alkyl group is preferably 1 to 18, more preferably 1 to 10, more preferably 1 to 6, and still more preferably 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, and an n-hexyl group. Of these, a methyl group and an ethyl group are preferred, and a methyl group is more preferred.

[0023] The number of carbon atoms in the cycloalkyl group is preferably 3 to 10, more preferably 5 to 10, and even more preferably 5 or 6. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

[0024] The number of carbon atoms in the aryl group is preferably 6 to 14, more preferably 6 to 10, and even more preferably 6 to 8. Examples of the aryl group include a phenyl group, a naphthyl group, a 2-methylphenyl group, a 3-methylphenyl group, a 4-methylphenyl group, and a 3-isopropylphenyl group.

[0025] In the two-component curing coating agent of the present invention, the polyol (P) contained in the base agent and the polyisocyanate (I) contained in the curing agent are reacted to form polyurethane, thereby curing the two-component curing coating agent to form a release layer. In the present invention, the release properties of the release layer can be improved by using a (meth)acrylic polyol containing a siloxane bond as the polyol (P) contained in the base agent. However, simply using a (meth)acrylic polyol containing a siloxane bond can sometimes reduce the extensibility of the release layer, making it difficult to achieve both extensibility and releasability in the release layer.

[0026] As a result of further investigations, the present inventors have found that by using (meth)acrylic polyols (A) and (B) each having a siloxane bond content within a predetermined range, it is possible to achieve both elongation and releasability in the release layer. Although the mechanism by which such an effect is obtained is not clear, the following mechanism is thought to be the cause.

[0027] The siloxane bonds contained in the (meth)acrylic polyol have the property of easily orienting toward the surface of the release layer. Therefore, in a two-component curing coating agent, by using a combination of (meth)acrylic polyols (A) and (B) each having a siloxane bond content within a predetermined range as the polyol (P) contained in the main agent, the (meth)acrylic polyol (B) with a high siloxane bond content is easily transferred to the surface of the release layer formed using the two-component curing coating agent, and the concentration of siloxane bonds on the surface of the release layer can be moderately increased. This can improve the release properties of the release layer. On the other hand, as the (meth)acrylic polyol (B) migrates to the surface of the release layer, the (meth)acrylic polyol (A) with a low siloxane bond content is easily transferred into the interior of the release layer, and by having a large amount of (meth)acrylic polyol (A) present inside the release layer, the decrease in the elongation of the release layer can be reduced.

[0028] As described above, in the two-component curing coating agent of the present invention, by using a combination of (meth)acrylic polyols (A) and (B) as the polyol (P) contained in the main agent, it is possible to provide a release layer that has both releasability and elongation. Note that the above mechanism is based on the speculation of the present inventors, and the present invention is not limited to the above mechanism.

[0029] [Base Agent] The two-component curing coating agent of the present invention contains a base agent containing a polyol (P). The polyol (P) contained in the base agent contains a (meth)acrylic polyol (A) and a (meth)acrylic polyol (B).

[0030] Here, (meth)acrylic means acrylic or methacrylic, and (meth)acrylate means acrylate or methacrylate.

[0031] [(Meth)acrylic polyol (A)] The (meth)acrylic polyol (A) contained in the base resin contains a structural unit (S1) having a siloxane bond represented by the above formula (1).

[0032] The content of the structural unit (S1) having a siloxane bond represented by the above formula (1) in the (meth)acrylic polyol (A) exceeds 0% by mass, but is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more. The content of the structural unit (S1) having a siloxane bond represented by the above formula (1) in the (meth)acrylic polyol (A) is less than 12% by mass, but is preferably 11% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less. By making the content of the structural unit (S1) exceed 0% by mass, the compatibility of the (meth)acrylic polyol (A) with the (meth)acrylic polyol (B) can be improved, thereby reducing the decrease in the elongation of the release layer. By making the content of the structural unit (S1) less than 12% by mass, the content of the siloxane bond in the release layer can be kept within an appropriate range, thereby reducing the decrease in the elongation of the release layer.

[0033] The content of the structural unit (S1) having a siloxane bond represented by the above formula (1) in the (meth)acrylic polyol can be determined by a nuclear magnetic resonance spectrometer ( 1 Measurement can be performed using H-NMR under the following measurement conditions: (Measurement conditions) Measurement equipment: Ascend™ 400 manufactured by Bruker Solvent: Deuterated chloroform Sample concentration: 50 mg / mL Observation frequency: 400 MHz Chemical shift reference: Chloroform Number of scans: 64 Measurement temperature: 25°C

[0034] The (meth)acrylic polyol (A) is a polymer of a (meth)acrylic monomer and has a hydroxyl group at the end or in a side chain. The (meth)acrylic polyol (A) can be obtained by polymerizing the (meth)acrylic monomer in the presence of a radical polymerization initiator using a conventional method for producing an acrylic polymer.

[0035] (Siloxane Bond-Containing (Meth)Acrylic Monomer (a1)) The (meth)acrylic polyol (A) preferably contains a siloxane bond-containing (meth)acrylic monomer (a1) unit. That is, the (meth)acrylic polyol (A) is preferably a polymer of a (meth)acrylic monomer containing the siloxane bond-containing (meth)acrylic monomer (a1).

[0036] The siloxane bond-containing (meth)acrylic monomer (a1) preferably contains a structural unit (S1) having a siloxane bond represented by the above formula (1). The structural unit (S1) having a siloxane bond represented by the above formula (1) contained in the siloxane bond-containing (meth)acrylic monomer (a1) may be the same as the structural unit (S1) having a siloxane bond represented by the above formula (1) contained in the above-mentioned (meth)acrylic polyol (A), and therefore a detailed description thereof will be omitted here. By including the structural unit (S1) having a siloxane bond represented by the above formula (1) in the siloxane bond-containing (meth)acrylic monomer (a1), the structural unit (S1) having a siloxane bond represented by the above formula (1) can be introduced into the (meth)acrylic polyol (A).

[0037] The siloxane bond-containing (meth)acrylic monomer (a1) is not particularly limited as long as it is a known monomer, but preferred examples include monomers represented by the following formula (2).

[0038] (In formula (2), R 5 is an alkyl group having 1 to 12 carbon atoms, and R 6 is an alkylene group having 1 to 10 carbon atoms, and R 7 represents a hydrogen atom or a methyl group, and p represents an integer of 2 or more.

[0039] In formula (2), R 5 The number of carbon atoms in the alkyl group represented by R is preferably 1 to 12, and more preferably 1 to 5. 5 Examples of the alkyl group represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, etc. Among these, a methyl group, an ethyl group, and an n-butyl group are preferred, and an n-butyl group is more preferred.

[0040] In formula (2), R 6 The alkylene group represented by the formula (I) preferably has 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms. 6 Examples of the alkylene group represented by the formula include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, etc. Among these, an n-propylene group (-CH-CH-CH-) is preferred.

[0041] In formula (2), p is preferably 2 or more, more preferably 5 or more, and more preferably 10 or more. In formula (2), p is preferably 300 or less, more preferably 200 or less, and more preferably 150 or less.

[0042] Furthermore, the siloxane bond-containing (meth)acrylic monomer (a1) preferably includes a monomer represented by the following formula (3):

[0043] (In formula (3), R 8 and R 11 are each a hydrogen atom or a methyl group, and R9 and R 10 are each an alkylene group having 1 to 10 carbon atoms, and q is an integer of 2 or more.

[0044] In formula (3), R 9 and R 10 The number of carbon atoms in each alkylene group represented by R is preferably 1 to 10, and more preferably 1 to 5. 9 and R 10 Examples of the alkylene group represented by R include a methylene group, an ethylene group, an n-propylene group, and an n-butylene group. 9 and R 10 may be the same or different.

[0045] In formula (3), q is preferably 2 or more, more preferably 5 or more, and more preferably 10 or more. In formula (3), q is preferably 300 or less, more preferably 200 or less, and more preferably 150 or less.

[0046] Specific examples of the siloxane bond-containing (meth)acrylic monomer (a1) include α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane, α-mono(methacryloxymethyl)polydimethylsiloxane, and α,ω-di(methacryloxymethyl)polydimethylsiloxane.

[0047] The siloxane bond-containing (meth)acrylic monomer (a1) preferably contains at least one of the monomer represented by the above formula (2) and the monomer represented by the above formula (3), and may contain both monomers. Of these, the siloxane bond-containing (meth)acrylic monomer (a1) is preferably the monomer represented by the above formula (2), and more preferably α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane. The siloxane bond-containing (meth)acrylic monomer (a1) may be used alone or in combination of two or more types.

[0048] The number average molecular weight (Mn) of the siloxane bond-containing (meth)acrylic monomer (a1) is preferably 500 or more, more preferably 1000 or more, more preferably 5000 or more, and more preferably 8500 or more. The number average molecular weight (Mn) of the siloxane bond-containing (meth)acrylic monomer (a1) is preferably 50000 or less, more preferably 25000 or less, and more preferably 15000 or less. When the number average molecular weight (Mn) of the siloxane bond-containing (meth)acrylic monomer (a1) is 500 or more, the releasability of the release layer can be improved. When the number average molecular weight (Mn) of the siloxane bond-containing (meth)acrylic monomer (a1) is 50000 or less, the decrease in elongation of the release layer can be reduced.

[0049] The number average molecular weight (Mn) of a siloxane bond-containing (meth)acrylic monomer refers to the value obtained by converting the molecular weight measured by gel permeation chromatography (GPC) into polystyrene equivalent. For example, it can be measured under the following measurement conditions. The siloxane bond-containing (meth)acrylic monomer is dissolved in tetrahydrofuran to obtain a measurement sample with a siloxane bond-containing (meth)acrylic monomer concentration of 2.0 g / L. Using this measurement sample, the number average molecular weight of the siloxane bond-containing (meth)acrylic monomer can be measured using a gel permeation chromatograph (GPC) equipped with a differential refractive index detector (RID) under the following measurement device and measurement conditions. Measurement equipment: Tosoh Corporation, product name "HLC-8320GPC" Differential refractive index detector: RI detector built into the above measurement equipment Column: Tosoh Corporation, product name "TSKgel Super HZM-H", two columns Mobile phase: tetrahydrofuran Column flow rate: 0.35 mL / min Sample concentration: 2.0 g / L Injection volume: 10 μL Measurement temperature: 40°C Molecular weight marker: standard polystyrene (standard material manufactured by POLYMER LABORATORIES LTD.) (POLYSTYRENE-MEDIUM MOLECULAR WEIGHT CALIBRATION KIT)

[0050] The content of the siloxane bond-containing (meth)acrylic monomer (a1) unit in the (meth)acrylic polyol (A) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, more preferably 1% by mass or more, and more preferably 3% by mass or more. The content of the siloxane bond-containing (meth)acrylic monomer (a1) unit in the (meth)acrylic polyol (A) is preferably less than 12.1% by mass, more preferably less than 12% by mass, more preferably 11% by mass or less, more preferably 10% by mass or less, and more preferably 8% by mass or less. By setting the content of the siloxane bond-containing (meth)acrylic monomer (a1) unit within the above range, it is possible to reduce the decrease in elongation of the release layer.

[0051] (Hydroxyl Group-Containing (Meth)Acrylic Monomer (a2)) The (meth)acrylic polyol (A) preferably further contains a hydroxyl group-containing (meth)acrylic monomer (a2) unit. That is, the (meth)acrylic polyol (A) is preferably a polymer of (meth)acrylic monomers including a siloxane bond-containing (meth)acrylic monomer (a1) and a hydroxyl group-containing (meth)acrylic monomer (a2). By using the hydroxyl group-containing (meth)acrylic monomer (a2), hydroxyl groups can be introduced into the (meth)acrylic polyol (A).

[0052] The hydroxyl group-containing (meth)acrylic monomer (a2) may be a hydroxyalkyl (meth)acrylate. The hydroxyl group-containing (meth)acrylic monomer (a2) preferably does not contain a siloxane bond. Therefore, the hydroxyl group-containing (meth)acrylic monomer (a2) preferably does not contain a structural unit (S1) having a siloxane bond represented by the above formula (1).

[0053] Specific examples of the hydroxyl group-containing (meth)acrylic monomer (a2) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate. Of these, 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate are preferred, and 2-hydroxyethyl (meth)acrylate is more preferred. The hydroxyl group-containing (meth)acrylic monomer (a2) may be used alone or in combination of two or more.

[0054] The content of the hydroxyl group-containing (meth)acrylic monomer (a2) units in the (meth)acrylic polyol (A) is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. The content of the hydroxyl group-containing (meth)acrylic monomer (a2) units in the (meth)acrylic polyol (A) is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. By setting the content of the hydroxyl group-containing (meth)acrylic monomer (a2) units to 1% by mass or more, urethane bonds can be appropriately formed during the reaction between the (meth)acrylic polyol (A) and the polyisocyanate (I), thereby reducing the decrease in elongation of the release layer. By setting the content of the hydroxyl group-containing (meth)acrylic monomer (a2) units to 50% by mass or less, the compatibility of the (meth)acrylic polyol (A) with other components can be maintained, and the high elongation of the release layer can be maintained.

[0055] ((Meth)acrylic Monomer (a3) ​​Having a Hydrocarbon Group) The (meth)acrylic polyol (A) preferably further contains a (meth)acrylic monomer (a3) ​​unit having a hydrocarbon group. That is, the (meth)acrylic polyol (A) is preferably a (meth)acrylic monomer polymer including a siloxane bond-containing (meth)acrylic monomer (a1), a hydroxyl group-containing (meth)acrylic monomer (a2), and a hydrocarbon group-containing (meth)acrylic monomer (a3).

[0056] The (meth)acrylic monomer (a3) ​​having a hydrocarbon group preferably does not contain a hydroxyl group. The (meth)acrylic monomer (a3) ​​having a hydrocarbon group preferably does not contain a siloxane bond. Therefore, the (meth)acrylic monomer (a3) ​​having a hydrocarbon group preferably does not contain a structural unit (S1) having a siloxane bond represented by the above formula (1).

[0057] The hydrocarbon group of the (meth)acrylic monomer (a3) ​​having a hydrocarbon group may be any of linear, branched, and cyclic. The hydrocarbon group of the (meth)acrylic monomer (a3) ​​having a hydrocarbon group is preferably a linear or branched alkyl group or a cyclic hydrocarbon group, and more preferably a linear or branched alkyl group.

[0058] Specific examples of the (meth)acrylic monomer (a3) ​​having a hydrocarbon group include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, and decyl (meth)acrylate. and (meth)acrylic monomers having a cyclic hydrocarbon group such as benzyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-butylcyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, isobornyl (meth)acrylate, and tricyclodecanyl (meth)acrylate. Among these, alkyl (meth)acrylates are preferred, and methyl (meth)acrylate and n-butyl (meth)acrylate are more preferred. The (meth)acrylic monomers (a3) ​​having a hydrocarbon group may be used alone or in combination of two or more.

[0059] The content of the (meth)acrylic monomer (a3) ​​unit having a hydrocarbon group in the (meth)acrylic polyol (A) is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. The content of the (meth)acrylic monomer (a3) ​​unit having a hydrocarbon group in the (meth)acrylic polyol (A) is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. By setting the content of the (meth)acrylic monomer (a3) ​​unit having a hydrocarbon group to 40% by mass or more, the (meth)acrylic polyol (A) can easily migrate into the release layer, thereby reducing the decrease in the extensibility of the release layer. By setting the content of the (meth)acrylic monomer (a3) ​​unit having a hydrocarbon group to 95% by mass or less, the releasability and extensibility of the release layer can be improved.

[0060] The content of the (meth)acrylic polyol (A) in the polyol (P) is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more. The content of the (meth)acrylic polyol (A) in the polyol (P) is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less. By setting the content of the (meth)acrylic polyol (A) within the above range, it is possible to reduce a decrease in the elongation of the release layer.

[0061] [(Meth)acrylic polyol (B)] The polyol (P) contained in the base resin contains a (meth)acrylic polyol (B). The (meth)acrylic polyol (B) contains a structural unit (S1) having a siloxane bond represented by the above formula (1).

[0062] The content of the structural unit (S1) having a siloxane bond represented by the above formula (1) in the (meth)acrylic polyol (B) is 12% by mass or more, preferably 15% by mass, more preferably 19% by mass or more, and even more preferably 21% by mass or more. By making the content of the structural unit (S1) 12% by mass or more, the (meth)acrylic polyol (B) becomes easy to migrate to the surface of the release layer, and the content of the siloxane bond on the surface of the release layer increases, thereby improving the releasability of the release layer.

[0063] The content of the structural unit (S1) having a siloxane bond represented by the above formula (1) in the (meth)acrylic polyol (B) is 30% by mass or less, preferably 28% by mass or less. By setting the content of the structural unit (S1) to 30% by mass or less, it is possible to reduce the deterioration of the performance of the semiconductor package caused by the bleeding out of the (meth)acrylic polyol (B) onto the surface of the release layer, as described below.

[0064] The release layer is formed by the reaction of the polyol (P) contained in the base agent with the polyisocyanate (I) contained in the curing agent, but the (meth)acrylic polyol (B) that did not participate in the reaction may remain in the final release layer. When the release sheet is heated in the semiconductor encapsulation process, the (meth)acrylic polyol (B) remaining in the release layer may bleed out onto the surface of the release layer. Furthermore, when a siloxane bond-containing (meth)acrylic monomer (b1) is used as a raw material for the (meth)acrylic polyol (B), the siloxane bond-containing (meth)acrylic monomer (b1) may contain low-molecular-weight siloxanes, such as non-functional cyclic siloxanes, generated as by-products during its synthesis. These low-molecular-weight siloxanes may bleed out onto the surface of the release layer together with the remaining (meth)acrylic polyol (B). If the bled-out (meth)acrylic polyol (B) or low-molecular-weight siloxane adheres to a semiconductor package, it can cause the semiconductor package to become cloudy, have contact problems, inhibit adhesion, and hydrophobize the surface, thereby reducing the performance of the semiconductor package. In order to reduce the performance degradation of the semiconductor package due to the bleed-out of components containing siloxane bonds, the content of the structural unit (S1) in the (meth)acrylic polyol (B) is set to 30% by mass or less.

[0065] The (meth)acrylic polyol (B) is a polymer of a (meth)acrylic monomer and has a hydroxyl group at the end or in a side chain. The (meth)acrylic polyol (B) can be obtained by polymerizing the (meth)acrylic monomer in the presence of a radical polymerization initiator using a conventional method for producing an acrylic polymer.

[0066] (Siloxane Bond-Containing (Meth)Acrylic Monomer (b1)) The (meth)acrylic polyol (B) preferably contains a siloxane bond-containing (meth)acrylic monomer (b1) unit. That is, the (meth)acrylic polyol (B) is preferably a polymer of a (meth)acrylic monomer containing the siloxane bond-containing (meth)acrylic monomer (b1).

[0067] The siloxane bond-containing (meth)acrylic monomer (b1) preferably contains a structural unit (S1) having a siloxane bond represented by the above formula (1). The structural unit (S1) having a siloxane bond represented by the above formula (1) contained in the siloxane bond-containing (meth)acrylic monomer (b1) may be the same as the structural unit (S1) having a siloxane bond represented by the above formula (1) contained in the above-mentioned (meth)acrylic polyol (B), and therefore a detailed description thereof will be omitted here. By including the structural unit (S1) having a siloxane bond represented by the above formula (1) in the siloxane bond-containing (meth)acrylic monomer (b1), the structural unit (S1) having a siloxane bond represented by the above formula (1) can be introduced into the (meth)acrylic polyol (B).

[0068] The siloxane bond-containing (meth)acrylic monomer (b1) can be any known monomer without any particular limitation, and examples thereof include the monomer represented by the above formula (2). Note that the monomer represented by the above formula (2) contained in the siloxane bond-containing (meth)acrylic monomer (b1) is the same as the monomer represented by the above formula (2) in the siloxane bond-containing (meth)acrylic monomer (a1) of the (meth)acrylic polyol (A), and therefore a detailed description thereof will be omitted here.

[0069] In formula (2), R 5 The number of carbon atoms in the alkyl group represented by R is preferably 1 to 12, and more preferably 1 to 5. 5 Examples of the alkyl group represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, etc. Among these, a methyl group, an ethyl group, and an n-butyl group are preferred, and an n-butyl group is more preferred.

[0070] In formula (2), R 6 The alkylene group represented by the formula (I) preferably has 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms. 6Examples of the alkylene group represented by the formula include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, etc. Among these, an n-propylene group (-CH-CH-CH-) is preferred.

[0071] In formula (2), p is preferably 2 or more, more preferably 5 or more, and more preferably 10 or more. In formula (2), p is preferably 300 or less, more preferably 200 or less, and more preferably 150 or less.

[0072] Preferred examples of the siloxane bond-containing (meth)acrylic monomer (b1) include the monomer represented by the above formula (3). The monomer represented by the above formula (3) is the same as the monomer represented by the above formula (3) in the siloxane bond-containing (meth)acrylic monomer (a1) of the (meth)acrylic polyol (A), and therefore a detailed description thereof will be omitted here.

[0073] In formula (3), R 9 and R 10 The number of carbon atoms in each alkylene group represented by R is preferably 1 to 10, and more preferably 1 to 5. 9 and R 10 Examples of the alkylene group represented by R include a methylene group, an ethylene group, an n-propylene group, and an n-butylene group. 9 and R 10 may be the same or different.

[0074] In formula (3), q is preferably 2 or more, more preferably 5 or more, and more preferably 10 or more. In formula (3), q is preferably 300 or less, more preferably 200 or less, and more preferably 150 or less.

[0075] Specific examples of the siloxane bond-containing (meth)acrylic monomer (b1) include α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane, α-mono(methacryloxymethyl)polydimethylsiloxane, and α,ω-di(methacryloxymethyl)polydimethylsiloxane.

[0076] The siloxane bond-containing (meth)acrylic monomer (b1) preferably contains at least one of the monomer represented by the above formula (2) and the monomer represented by the above formula (3), and may contain both monomers. Among these, the siloxane bond-containing (meth)acrylic monomer (b1) is preferably the monomer represented by the above formula (2), and more preferably α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane. The siloxane bond-containing (meth)acrylic monomer (b1) may be used alone or in combination of two or more types.

[0077] The number average molecular weight (Mn) of the siloxane bond-containing (meth)acrylic monomer (b1) is preferably 500 or more, more preferably 1000 or more, more preferably 5000 or more, and more preferably 8500 or more. The number average molecular weight (Mn) of the siloxane bond-containing (meth)acrylic monomer (b1) is preferably 50000 or less, more preferably 25000 or less, and more preferably 15000 or less. When the number average molecular weight (Mn) of the siloxane bond-containing (meth)acrylic monomer (b1) is 500 or more, the releasability of the release layer can be improved. When the number average molecular weight (Mn) of the siloxane bond-containing (meth)acrylic monomer (b1) is 50000 or less, the decrease in elongation of the release layer can be reduced.

[0078] The content of the siloxane bond-containing (meth)acrylic monomer (b1) unit in the (meth)acrylic polyol (B) is preferably 12% by mass or more, more preferably 15% by mass, more preferably 19% by mass or more, and even more preferably 21% by mass or more. The content of the siloxane bond-containing (meth)acrylic monomer (b1) unit in the (meth)acrylic polyol (B) is preferably 30% by mass or less, more preferably 28% by mass or less. By setting the content of the siloxane bond-containing (meth)acrylic monomer (b1) unit to 12% by mass or more, the releasability of the release layer can be improved. By setting the content of the siloxane bond-containing (meth)acrylic monomer (b1) unit to 30% by mass or less, the bleed-out of the (meth)acrylic polyol (B) onto the surface of the release layer can be reduced.

[0079] (Hydroxyl Group-Containing (Meth)Acrylic Monomer (b2)) The (meth)acrylic polyol (B) preferably further contains a hydroxyl group-containing (meth)acrylic monomer (b2) unit. That is, the (meth)acrylic polyol (B) is preferably a polymer of (meth)acrylic monomers including a siloxane bond-containing (meth)acrylic monomer (b1) and a hydroxyl group-containing (meth)acrylic monomer (b2). By using the hydroxyl group-containing (meth)acrylic monomer (b2), hydroxyl groups can be introduced into the (meth)acrylic polyol (B).

[0080] The hydroxyl group-containing (meth)acrylic monomer (b2) may be a hydroxyalkyl (meth)acrylate. The hydroxyl group-containing (meth)acrylic monomer (b2) preferably does not contain a siloxane bond. Therefore, the hydroxyl group-containing (meth)acrylic monomer (b2) preferably does not contain a structural unit (S1) having a siloxane bond represented by the above formula (1).

[0081] Specific examples of the hydroxyl group-containing (meth)acrylic monomer (b2) include the same as the specific examples described above for the hydroxyl group-containing (meth)acrylic monomer (a2). Among these, 4-hydroxybutyl(meth)acrylate and 2-hydroxyethyl(meth)acrylate are preferred, and 2-hydroxyethyl(meth)acrylate is more preferred. The hydroxyl group-containing (meth)acrylic monomer (b2) may be used alone or in combination of two or more.

[0082] The content of the hydroxyl group-containing (meth)acrylic monomer (b2) units in the (meth)acrylic polyol (B) is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. The content of the hydroxyl group-containing (meth)acrylic monomer (b2) units in the (meth)acrylic polyol (B) is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. By setting the content of the hydroxyl group-containing (meth)acrylic monomer (b2) units to 1% by mass or more, urethane bonds can be appropriately formed during the reaction between the (meth)acrylic polyol (B) and the polyisocyanate (I), thereby reducing the decrease in elongation of the release layer. By setting the content of the hydroxyl group-containing (meth)acrylic monomer (b2) units to 50% by mass or less, the compatibility of the (meth)acrylic polyol (B) with other components can be maintained, and high elongation properties with good releasability can be maintained.

[0083] ((Meth)acrylate (b3) Having a Hydrocarbon Group) The (meth)acrylic polyol (B) preferably further contains a (meth)acrylate (b3) unit having a hydrocarbon group. That is, the (meth)acrylic polyol (B) is preferably a polymer of (meth)acrylic monomers including a siloxane bond-containing (meth)acrylic monomer (b1), a hydroxyl group-containing (meth)acrylic monomer (b2), and a (meth)acrylate (b3) having a hydrocarbon group.

[0084] The (meth)acrylate (b3) having a hydrocarbon group preferably does not contain a hydroxyl group. The (meth)acrylate (b3) having a hydrocarbon group preferably does not contain a siloxane bond. Therefore, the (meth)acrylate (b3) having a hydrocarbon group preferably does not contain a structural unit (S1) having a siloxane bond represented by the above formula (1).

[0085] The hydrocarbon group of the (meth)acrylate (b3) having a hydrocarbon group may be any of linear, branched, and cyclic. The hydrocarbon group of the (meth)acrylate (b3) having a hydrocarbon group is preferably a linear or branched alkyl group or a cyclic hydrocarbon group, and more preferably a linear or branched alkyl group.

[0086] Specific examples of the (meth)acrylate (b3) having a hydrocarbon group include the same as the specific examples described above for the (meth)acrylate (a3) ​​having a hydrocarbon group. Among these, alkyl (meth)acrylates are preferred, and methyl (meth)acrylate and n-butyl (meth)acrylate are more preferred. The (meth)acrylate (b3) having a hydrocarbon group may be used alone or in combination of two or more.

[0087] The content of the (meth)acrylate (b3) units having a hydrocarbon group in the (meth)acrylic polyol (B) is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more. The content of the (meth)acrylate (b3) units having a hydrocarbon group in the (meth)acrylic polyol (B) is preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. By setting the content of the (meth)acrylate (b3) units having a hydrocarbon group to 20% by mass or more, the compatibility of the (meth)acrylic polyol (B) with other components can be maintained, and a decrease in the elongation of the release layer can be reduced. By setting the content of the (meth)acrylate (b3) units having a hydrocarbon group to 85% by mass or less, the releasability and elongation of the release layer can be improved.

[0088] The content of (meth)acrylic polyol (B) in polyol (P) is preferably 1% by mass or more, more preferably 3% by mass or more, and more preferably 5% by mass or more. The content of (meth)acrylic polyol (B) in polyol (P) is preferably 40% by mass or less, more preferably 37% by mass or less, and more preferably 35% by mass or less. By setting the content of (meth)acrylic polyol (B) to 1% by mass or more, the releasability of the release layer can be improved. By setting the content of (meth)acrylic polyol (B) to 40% by mass or less, the bleeding out of (meth)acrylic polyol (B) onto the surface of the release layer can be reduced.

[0089] The total content of (meth)acrylic polyols (A) and (B) in polyol (P) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 18% by mass or more. The total content of (meth)acrylic polyols (A) and (B) in polyol (P) is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 88% by mass or less. By making the total content of (meth)acrylic polyols (A) and (B) 10% by mass or more, the releasability of the release layer can be improved. By making the total content of (meth)acrylic polyols (A) and (B) 95% by mass or less, the elongation of the release layer can be improved.

[0090] In the polyol (P), the content ratio of the (meth)acrylic polyol (A) to the (meth)acrylic polyol (B) [mass of the (meth)acrylic polyol (A) / mass of the (meth)acrylic polyol (B)] is preferably 0.2 or more, more preferably 0.3 or more, more preferably 1 or more, more preferably 1.5 or more, more preferably 2.0 or more, more preferably 2.5 or more, and more preferably 3.0 or more. In the polyol (P), the content ratio of the (meth)acrylic polyol (A) to the (meth)acrylic polyol (B) [mass of the (meth)acrylic polyol (A) / mass of the (meth)acrylic polyol (B)] is preferably 70 or less, more preferably 65 or less, more preferably 60 or less, more preferably 50 or less, more preferably 40 or less, more preferably 30 or less, more preferably 20 or less, and more preferably 10 or less. When the content ratio of the (meth)acrylic polyol (A) to the (meth)acrylic polyol (B) [mass of the (meth)acrylic polyol (A) / mass of the (meth)acrylic polyol (B)] is 0.2 or more, the elongation of the release layer is improved. Furthermore, bleeding out of the (meth)acrylic polyol (B) onto the surface of the release layer can be reduced. When the content ratio of the (meth)acrylic polyol (A) to the (meth)acrylic polyol (B) [mass of the (meth)acrylic polyol (A) / mass of the (meth)acrylic polyol (B)] is 70 or less, the releasability of the release layer is improved.

[0091] [Other Polyols] The polyol (P) contained in the base material preferably contains other polyols in addition to the above-mentioned (meth)acrylic polyols (A) and (B). Examples of other polyols include polyester polyols, polyether polyols, polycarbonate polyols, and alkyl polyols. Among these, polyester polyols, polyether polyols, and polycarbonate polyols are preferred. By using these, the release properties and elongation properties of the release layer can be improved. The other polyols may be used alone or in combination of two or more.

[0092] (Polyester Polyol) Examples of polyester polyols include lactone-based polyester polyols (1) obtained by ring-opening polymerization of lactones with low-molecular-weight polyols; alcohol-modified lactone-based polyester polyols (2) obtained by copolymerizing lactone-based polyester polyols (1) with dihydric alcohols; and polycondensation-based polyester polyols (3) which are polycondensation products of low-molecular-weight polyols and polybasic acids.

[0093] The lactone polyester polyol (1) can be obtained by ring-opening polymerization of a lactone with a low molecular weight polyol as an initiator.

[0094] Examples of low molecular weight polyols include compounds having two or more hydroxyl groups and a molecular weight of less than 400, preferably less than 300. Examples of low molecular weight polyols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2,2-trimethylpentanediol, 3,3-dimethylolheptane, alkane (C7-20) diols, 1,3- or 1,4-cyclohexanedimethanol and mixtures thereof, 1,3- or 1,4-cyclohexanediol and mixtures thereof, hydrogenated bisphenol A, 1,4-dihydroxy-2-butene, 2,6-dimethyl Examples of low molecular weight polyols include dihydric alcohols such as 1-octene-3,8-diol, bisphenol A, diethylene glycol, triethylene glycol, and dipropylene glycol; trihydric alcohols such as glycerin, trimethylolpropane, and triisopropanolamine; tetrahydric alcohols such as tetramethylolmethane (pentaerythritol) and diglycerin; pentahydric alcohols such as xylitol; hexahydric alcohols such as sorbitol, mannitol, allitol, iditol, dulcitol, altritol, inositol, and dipentaerythritol; heptahydric alcohols such as perseitol; and octahydric alcohols such as sucrose. Low molecular weight polyols may be used alone or in combination of two or more.

[0095] Examples of lactones include ε-caprolactone and γ-valerolactone. These lactones may be used alone or in combination. Examples of the lactone-based polyester polyol (1) include polycaprolactone polyols obtained by ring-opening polymerization of ε-caprolactone with a low-molecular-weight polyol, and polyvalerolactone polyols obtained by ring-opening polymerization of γ-valerolactone with a low-molecular-weight polyol.

[0096] As the lactone-based polyester polyol (1), polycaprolactone polyol is preferred, and polycaprolactone triol obtained by ring-opening polymerization of ε-caprolactone with a low molecular weight triol, and polycaprolactone diol obtained by ring-opening polymerization of ε-caprolactone with a low molecular weight diol are more preferred.

[0097] The polycondensation polyester polyol (3) can be obtained by polycondensation of a low-molecular-weight polyol with a polybasic acid.

[0098] Examples of the low-molecular-weight polyol in the polycondensation polyester polyol (3) include the same low-molecular-weight polyols as those mentioned above in the lactone polyester polyol (1).

[0099] Examples of polybasic acids include oxalic acid, malonic acid, succinic acid, methylsuccinic acid, glutaric acid, adipic acid, 1,1-dimethyl-1,3-dicarboxypropane, 3-methyl-3-ethylglutaric acid, azelaic acid, sebacic acid, and other saturated aliphatic dicarboxylic acids (C11-13); for example, maleic acid, fumaric acid, itaconic acid, and other unsaturated aliphatic dicarboxylic acids; for example, orthophthalic acid, isophthalic acid, terephthalic acid, toluenedicarboxylic acid, naphthalenedicarboxylic acid, and other aromatic dicarboxylic acids; for example, hexacarboxylic acid, Examples of suitable polybasic acids include tetrahydrophthalic acid and other alicyclic dicarboxylic acids; other carboxylic acids such as dimer acid, hydrogenated dimer acid, and HET acid, and acid anhydrides derived from these carboxylic acids; for example, oxalic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, 2-alkyl (C12 to C18) succinic anhydride, tetrahydrophthalic anhydride, and trimellitic anhydride; and acid halides derived from these carboxylic acids, such as oxalic acid dichloride, adipic acid dichloride, and sebacic acid dichloride. The polybasic acids may be used alone or in combination of two or more.

[0100] The content of the polyester polyol in the polyol (P) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. The content of the polyester polyol in the polyol (P) is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. By setting the content of the polyester polyol within the above range, the releasability and elongation of the release layer can be improved.

[0101] (Polyether polyol) Examples of polyether polyols include aliphatic polyether polyols, alicyclic polyether polyols, etc. Examples of aliphatic polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyheptamethylene ether glycol, polydecamethylene ether glycol; polyhydric alcohols such as alkylene oxide-added polyols, such as pentaerythritol, dipentaerythritol, trimethylolpropane, and ethylene oxide-added triol of trimethylolpropane, propylene oxide-added triol of trimethylolpropane, ethylene oxide and propylene oxide-added triol of trimethylolpropane, ethylene oxide-added tetraol of pentaerythritol, and ethylene oxide-added hexaol of dipentaerythritol, or polyether polyols obtained by ring-opening polymerization of two or more kinds of ion-polymerizable cyclic compounds.

[0102] Examples of the ionically polymerizable cyclic compound include cyclic ethers such as ethylene oxide, propylene oxide, butene-1-oxide, isobutene oxide, 3,3-bis(chloromethyl)oxetane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, trioxane, tetraoxane, cyclohexene oxide, styrene oxide, epichlorohydrin, glycidyl ether, allyl glycidyl ether, allyl glycidyl carbonate, butadiene monoxide, isoprene monoxide, vinyloxetane, vinyltetrahydrofuran, vinylcyclohexene oxide, phenyl glycidyl ether, butyl glycidyl ether, and benzoic acid glycidyl ester. Specific examples of combinations of the two or more ionically polymerizable cyclic compounds include tetrahydrofuran and ethylene oxide, tetrahydrofuran and propylene oxide, tetrahydrofuran and 2-methyltetrahydrofuran, tetrahydrofuran and 3-methyltetrahydrofuran, ethylene oxide and propylene oxide, butene-1-oxide and ethylene oxide, and tetrahydrofuran, butene-1-oxide and ethylene oxide.

[0103] Examples of the alicyclic polyether polyol include alkylene oxide addition diols of hydrogenated bisphenol A, alkylene oxide addition diols of hydrogenated bisphenol F, and alkylene oxide addition diols of 1,4-cyclohexanediol.

[0104] The content of the polyether polyol in the polyol (P) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. On the other hand, the content of the polyether polyol in the polyol (P) is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. By setting the content of the polyether polyol within the above range, the releasability and elongation of the release layer can be improved.

[0105] (Polycarbonate Polyol) Examples of polycarbonate polyols include ring-opening polymers of ethylene carbonate using the low-molecular-weight polyols described above in the lactone-based polyester polyol (1) as an initiator, and amorphous polycarbonate polyols obtained by copolymerizing ring-opening polymers with dihydric alcohols such as 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol.

[0106] Specific examples of polycarbonate polyols include polyhexamethylene carbonate diol, polypentamethylene carbonate diol, polytetramethylene carbonate diol, poly(tetramethylene / hexamethylene) carbonate diol, and poly[cyclohexylenebis(methylene) / hexamethylene] carbonate diol. Poly(tetramethylene / hexamethylene) carbonate diol is a copolymer of 1,4-butanediol and 1,6-hexanediol with a dialkyl carbonate. Poly[cyclohexylenebis(methylene) / hexamethylene] carbonate diol is a copolymer of 1,4-cyclohexanedimethanol and 1,6-hexanediol with a dialkyl carbonate.

[0107] The content of the polycarbonate polyol in the polyol (P) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. On the other hand, the content of the polycarbonate polyol in the polyol (P) is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. By setting the content of the polycarbonate polyol within the above range, the releasability and elongation of the release layer can be improved.

[0108] (Alkyl Polyol) The alkyl polyol refers to a saturated hydrocarbon having a chain or saturated alicyclic structure, in which at least two hydrogen atoms in one molecule have been substituted with hydroxyl groups (—OH).

[0109] A chain saturated hydrocarbon in which at least two hydrogen atoms in one molecule are substituted with hydroxyl groups (—OH) is called a “chain alkyl polyol”.

[0110] A saturated hydrocarbon having a saturated alicyclic structure in which at least two hydrogen atoms in one molecule are substituted with hydroxyl groups (—OH) is called a “cycloalkyl polyol”.

[0111] The term "saturated alicyclic structure" refers to an alicyclic structure that does not contain unsaturated bonds such as carbon-carbon double bonds or carbon-carbon triple bonds. Examples of saturated alicyclic structures include cycloalkane structures such as cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cyclooctane structure, and cyclodecane structure, as well as tetrahydrodicyclopentadiene structure and adamantane structure. Examples of saturated hydrocarbons having a saturated alicyclic structure include dimethylcyclohexane, diethylcyclohexane, adamantane, tetrahydrodicyclopentadiene, and tetramethylcyclobutane.

[0112] The alkyl polyol has two or more hydroxyl groups per molecule. The alkyl polyol has preferably five or less hydroxyl groups per molecule, more preferably three or less hydroxyl groups per molecule. The alkyl polyol particularly preferably has two hydroxyl groups per molecule.

[0113] Specific examples of alkyl polyols include propanediol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2,4-diethyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 2-methyl-1,6-hexanediol, and 2-methyl-2-ethyl-1,3-propanediol. chain alkyl polyols such as 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 1,3,5-trimethyl-1,3-pentanediol, and 2,2,4-trimethyl-1,6-hexanediol; and cycloalkyl polyols such as cyclohexane dimethanols such as 1,2-cyclohexane dimethanol, 1,3-cyclohexane dimethanol, and 1,4-cyclohexane dimethanol, cyclohexane diethanols such as 1,2-cyclohexane diethanol, 1,3-cyclohexane diethanol, and 1,4-cyclohexane diethanol, tricyclodecane dimethanol, adamantanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol. The alkyl polyols may be used alone or in combination of two or more kinds.

[0114] The content of the alkyl polyol in the polyol (P) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. On the other hand, the content of the alkyl polyol in the polyol (P) is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. By setting the content of the alkyl polyol within the above range, the releasability and elongation of the release layer can be improved.

[0115] [Curing Agent] The two-component curing coating agent of the present invention contains a curing agent containing polyisocyanate (I). The polyisocyanate (I) has two or more isocyanate groups (-NCO) in one molecule, and preferably three or more.

[0116] The polyisocyanate (I) does not necessarily have to have a structural unit (S2) having a siloxane bond represented by the following formula (4), but it preferably does. Note that the "structural unit (S2) having a siloxane bond represented by the following formula (4)" may sometimes be simply referred to as the "structural unit (S2)."

[0117] (In formula (4), R 12 and R 13 each independently represents a hydrogen atom or a monovalent hydrocarbon group, and * represents a bond (single bond).

[0118] In formula (4), R 12 and R 13 are each independently a hydrogen atom or a monovalent hydrocarbon group. 12 and R 13 may be the same or different, but are preferably the same. Examples of the monovalent hydrocarbon group include an alkyl group, a cycloalkyl group, and an aryl group. Of these, an alkyl group is preferred.

[0119] The number of carbon atoms in the alkyl group is preferably 1 to 18, more preferably 1 to 10, more preferably 1 to 6, and still more preferably 1 to 3. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, and an n-hexyl group. Of these, a methyl group and an ethyl group are preferred, and a methyl group is more preferred.

[0120] The number of carbon atoms in the cycloalkyl group is preferably 3 to 10, more preferably 5 to 10, and even more preferably 5 or 6. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

[0121] The number of carbon atoms in the aryl group is preferably 6 to 14, more preferably 6 to 10, and even more preferably 6 to 8. Examples of the aryl group include a phenyl group, a naphthyl group, a 2-methylphenyl group, a 3-methylphenyl group, a 4-methylphenyl group, and a 3-isopropylphenyl group.

[0122] The content of the structural unit (S2) having a siloxane bond represented by the above formula (4) in the polyisocyanate (I) is preferably 0.5% by mass or more, more preferably 1% by mass or more, more preferably 10% by mass or more, more preferably 20% by mass or more, more preferably 25% by mass or more, and more preferably 30% by mass or more. By making the content of the structural unit (S2) having a siloxane bond represented by the above formula (4) 0.5% by mass or more, the releasability of the release layer can be improved.

[0123] The content of the structural unit (S2) having a siloxane bond represented by the above formula (4) in the polyisocyanate (I) is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. By setting the content of the structural unit (S2) to 50% by mass or less, it is possible to reduce the deterioration of the performance of the semiconductor package caused by the bleed-out of the polyisocyanate (I) containing the structural unit (S2), as described below.

[0124] The release layer is formed by the reaction of the polyol (P) contained in the base agent with the polyisocyanate (I) contained in the curing agent, but the polyisocyanate (I) containing the structural unit (S2) that did not participate in the reaction may remain in the finally obtained release layer. When the release sheet is heated in the semiconductor encapsulation process, the polyisocyanate (I) containing the structural unit (S2) remaining in the release layer may bleed out onto the surface of the release layer. Furthermore, when a polyol having a structural unit (S2) with a siloxane bond represented by the above formula (4) is used as the raw material for the polyisocyanate (I), the polyol may contain low-molecular-weight siloxanes such as non-functional cyclic siloxanes produced as by-products during its synthesis, and these low-molecular-weight siloxanes may bleed out onto the surface of the release layer together with the polyisocyanate (I) containing the remaining structural unit (S2). If the bled-out polyisocyanate (I) or low-molecular-weight siloxane adheres to a semiconductor package, it can cause the semiconductor package to become cloudy, have contact problems, inhibit adhesion, and hydrophobize the surface, thereby reducing the performance of the semiconductor package. In order to reduce such performance degradation of the semiconductor package, it is preferable to set the content of the structural unit (S2) in the polyisocyanate (I) to 50 mass% or less.

[0125] In addition, when the polyisocyanate (I) contains multiple types of polyisocyanates, such as a polyisocyanate (C) that does not have the structural unit (S2) and a polyisocyanate (D) that has the structural unit (S2), which will be described later, the content of the structural unit (S2) having a siloxane bond represented by the above formula (4) in the polyisocyanate (I) refers to the ratio of the total mass of the structural unit (S2) having a siloxane bond represented by the above formula (4) to the total mass of the multiple types of polyisocyanates.

[0126] The content of the structural unit (S2) having a siloxane bond represented by the above formula (4) in the polyisocyanate (I) can be measured by the same method as the above-mentioned method for measuring the content of the structural unit (S1) having a siloxane bond represented by the above formula (1) in the (meth)acrylic polyol.

[0127] The polyisocyanate (I) may not have the structural unit (S2). Therefore, the polyisocyanate (I) may contain only the polyisocyanate (C) that does not have the structural unit (S2). Furthermore, the polyisocyanate (I) preferably has the structural unit (S2). In such a case, the polyisocyanate (I) preferably contains the polyisocyanate (D) that has the structural unit (S2), and preferably contains the polyisocyanate (C) that does not have the structural unit (S2) and the polyisocyanate (D) that has the structural unit (S2). The polyisocyanate (D) that has the structural unit (S2) can improve the releasability of the release layer.

[0128] Specific examples of the polyisocyanate (C) that does not have the structural unit (S2) include aliphatic polyisocyanates that do not have the structural unit (S2), polyisocyanates that have an alicyclic structure that does not have the structural unit (S2), and modified products of these polyisocyanates. The polyisocyanates (C) that do not have the structural unit (S2) may be used alone or in combination of two or more.

[0129] Examples of aliphatic polyisocyanates not having the structural unit (S2) include acyclic aliphatic polyisocyanates not having the structural unit (S2), such as ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl)fumarate, bis(2-isocyanatoethyl)carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate. Of these, hexamethylene diisocyanate is preferred.

[0130] Examples of polyisocyanates having an alicyclic structure that do not have the structural unit (S2) include 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), isophorone diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), and 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated m-XDI).

[0131] Modified polyisocyanates not having the structural unit (S2) include isocyanurates, biurets, and adducts of the polyisocyanates not having the structural unit (S2). Three molecules of polyisocyanate can form an isocyanurate or biuret. Adducts include adducts (addition products) of polyisocyanates and polyols not having siloxane bonds. For example, a trimer adduct is formed by reacting trimethylolpropane with three molecules of polyisocyanate.

[0132] Examples of modified polyisocyanates that do not have the structural unit (S2) include biuret and isocyanurate forms of aliphatic polyisocyanates that do not have the structural unit (S2), such as ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, and dodecamethylene diisocyanate; biuret and isocyanurate forms of polyisocyanates that have an alicyclic structure that does not have the structural unit (S2), such as 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), isophorone diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), and 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated m-XDI); trimer adducts of trimethylolpropane (TMP) and hydrogenated MDI; Examples of the polyisocyanate include a trimer adduct of 3 moles of any one of polyisocyanates such as isophorone diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), and 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated m-XDI) with 1 mole of trimethylolpropane (TMP); an adduct of trimethylolpropane (TMP) with 2 moles of isophorone diisocyanate and 1 mole of hexamethylene diisocyanate (HDI); and a bifunctional polyurethane diisocyanate which is an adduct of a diol not having the structural unit (S2) with an aliphatic diisocyanate not having the structural unit (S2), such as ethylene diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate.

[0133] Examples of the polyisocyanate (C) that does not have the structural unit (S2) include the aliphatic polyisocyanates that do not have the structural unit (S2), polyisocyanates that have an alicyclic structure that do not have the structural unit (S2), and modified products thereof (isocyanurates, biurets, and adducts), each of which are described above. Among these, isocyanurates, biurets, and adducts of aliphatic polyisocyanates that do not have the structural unit (S2) are preferred, adducts of diols that do not have the structural unit (S2) and aliphatic diisocyanates that do not have the structural unit (S2) are more preferred, and adducts of diols that do not have the structural unit (S2) and 1,6-hexamethylene diisocyanate are more preferred. The polyisocyanates (C) that do not have the structural unit (S2) may be used alone or in combination of two or more types.

[0134] The polyisocyanate (D) having the structural unit (S2) is preferably a polyisocyanate (D) that is a reaction product of a polyisocyanate and a polyol having a structural unit (S2) having a siloxane bond represented by the above formula (4). It is preferable to obtain a polyisocyanate (D) having two or more isocyanate groups and a structural unit (S2) having a siloxane bond represented by the above formula (4) by reacting each of the hydroxyl groups of a polyol having a structural unit (S2) having a siloxane bond represented by the above formula (4) with an isocyanate group of the polyisocyanate to form a urethane bond. The polyisocyanate (D) having the structural unit (S2) may be used alone or in combination of two or more.

[0135] Examples of polyisocyanates constituting the polyisocyanate (D) include polyisocyanates that do not have the structural unit (S2). Specific examples of polyisocyanates that do not have the structural unit (S2) include aliphatic polyisocyanates that do not have the structural unit (S2), polyisocyanates having an alicyclic structure that do not have the structural unit (S2), and modified products of these polyisocyanates. Specific examples of these are the same as the specific examples described above for the polyisocyanate (C) that does not have the structural unit (S2), so detailed explanations will be omitted here. The polyisocyanates that constitute the polyisocyanate (D) may be used alone or in combination of two or more.

[0136] Examples of the structural unit (S2) in the polyol having the structural unit (S2) include the same as the "structural unit (S2) having a siloxane bond represented by the above formula (4)" in the polyisocyanate (I), and therefore detailed description thereof will be omitted here.

[0137] Specific examples of polyols having the structural unit (S2) include polyols represented by the following formula (5).

[0138] (In formula (5), R 14 , R 15 , R 16 , and R 17 may be the same or different and are alkylene groups having 1 to 10 carbon atoms, and m is an integer of 2 or more.

[0139] In formula (5), R 14 , R 15 , R 16 , and R 17 The number of carbon atoms in the alkylene group represented by the formula (I) is preferably 1 to 10, and more preferably 1 to 5. Examples of the alkylene group include a methylene group, an ethylene group, an n-propylene group, and an n-butylene group.

[0140] In formula (5), m is preferably 2 or more, more preferably 5 or more, and more preferably 10 or more. In formula (5), m is preferably 300 or less, more preferably 200 or less, and more preferably 150 or less.

[0141] The number average molecular weight (Mn) of the polyol having the structural unit (S2) is preferably 500 or more, more preferably 1000 or more, and more preferably 5000 or more. The number average molecular weight (Mn) of the polyol having the structural unit (S2) is preferably 25000 or less, more preferably 15000 or less, and more preferably 9000 or less. When the number average molecular weight (Mn) of the polyol is 500 or more, the release properties of the release layer can be improved. When the number average molecular weight (Mn) of the polyol is 25000 or less, the decrease in the elongation of the release layer can be reduced.

[0142] The number average molecular weight (Mn) of the polyol having the structural unit (S2) can be measured using the same method as the method for measuring the number average molecular weight (Mn) of the siloxane bond-containing (meth)acrylic monomer described above.

[0143] The polyisocyanate (D) having the structural unit (S2) is preferably a reaction product of an isocyanurate of an aliphatic polyisocyanate not having the structural unit (S2) with a polyol having the structural unit (S2), and more preferably a reaction product of an isocyanurate of hexamethylene diisocyanate with a polyol having the structural unit (S2).It is preferable to obtain a polyisocyanate (D) having two or more isocyanate groups and the structural unit (S2) by reacting each of the hydroxyl groups of the polyol having the structural unit (S2) with an isocyanate group of the polyisocyanate to form a urethane bond.

[0144] When producing polyisocyanate (D), a polyisocyanate having two or more isocyanate groups can be produced by subjecting an excess amount of polyisocyanate to a urethane reaction with a polyol having the structural unit (S2). It is preferred to subject each hydroxyl group of the polyol having the structural unit (S2) to a urethane reaction with a different polyisocyanate.

[0145] In the urethane reaction between a polyisocyanate and a polyol having the structural unit (S2), the equivalent ratio of the isocyanate groups of the polyisocyanate to the hydroxyl groups of the polyol having the structural unit (S2) (isocyanate group / hydroxyl group) is preferably 2.0 or more, and more preferably 2.5 or more. In the urethane reaction between a polyisocyanate and a polyol having the structural unit (S2), the equivalent ratio of the isocyanate groups of the polyisocyanate to the hydroxyl groups of the polyol having the structural unit (S2) (isocyanate group / hydroxyl group) is preferably 10.0 or less, and more preferably 9.0 or less. By setting the equivalent ratio (isocyanate group / hydroxyl group) to 2.0 or more, an excess of isocyanate groups relative to the hydroxyl groups can be subjected to the urethane reaction, and a polyisocyanate having two or more isocyanate groups per molecule can be obtained.

[0146] The equivalent ratio of the isocyanate groups of the polyisocyanate to the hydroxyl groups of the polyol having the structural unit (S2) (isocyanate groups / hydroxyl groups) is determined by dividing the number of isocyanate groups in the polyisocyanate by the number of hydroxyl groups in the polyol having the structural unit (S2).

[0147] The number of hydroxyl groups in a polyol having the structural unit (S2) is calculated based on the following formula. The hydroxyl value refers to a value obtained by measurement in accordance with 4.2 Method B of JIS K 1557-1:2007 (ISO 14900:2001) "Plastics - Test methods for polyurethane raw polyols - Part 1: Determination of hydroxyl value." Number of hydroxyl groups in a polyol containing the structural unit (S2) = Amount (g) of polyol having the structural unit (S2) used in the urethanization reaction × Hydroxyl value (mg KOH / g) / 56,100

[0148] The number of isocyanate groups in a polyisocyanate is calculated based on the following formula: The isocyanate equivalent is the value obtained by dividing the molecular weight of a polyisocyanate by the number of isocyanate groups in one molecule. Specifically, it is the value measured in accordance with JIS K1603. Number of isocyanate groups in a polyisocyanate = Amount (g) of polyisocyanate used in the urethanization reaction / Isocyanate equivalent

[0149] When the polyisocyanate (I) contains a polyisocyanate (C) that does not have the structural unit (S2) and a polyisocyanate (D) that has the structural unit (S2), the content of the polyisocyanate (C) that does not have the structural unit (S2) in the polyisocyanate (I) is preferably 30% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, and more preferably 60% by mass or more. When the polyisocyanate (I) contains a polyisocyanate (C) that does not have the structural unit (S2) and a polyisocyanate (D) that has the structural unit (S2), the content of the polyisocyanate (C) that does not have the structural unit (S2) in the polyisocyanate (I) is preferably 99% by mass or less.

[0150] When the polyisocyanate (I) contains a polyisocyanate (C) that does not have the structural unit (S2) and a polyisocyanate (D) that has the structural unit (S2), the content of the polyisocyanate (D) that has the structural unit (S2) in the polyisocyanate (I) is preferably 1% by mass or more. When the polyisocyanate (I) contains a polyisocyanate (C) that does not have the structural unit (S2) and a polyisocyanate (D) that has the structural unit (S2), the content of the polyisocyanate (D) that has the structural unit (S2) in the polyisocyanate (I) is preferably 70% by mass or less, more preferably 60% by mass or less, more preferably 50% by mass or less, and preferably 40% by mass or less. By setting the content of the polyisocyanate (D) that has the structural unit (S2) to 1% by mass or more, the releasability of the release layer can be improved. By setting the content of the polyisocyanate (D) having the structural unit (S2) to 70 mass% or less, it is possible to reduce the bleeding out of the polyisocyanate (D) having the structural unit (S2) onto the surface of the release layer.

[0151] In the two-component curing coating agent, the equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate groups of the polyisocyanate (I) contained in the curing agent to the hydroxyl groups of the polyol (P) contained in the base agent is preferably 0.7 or more, more preferably 0.8 or more. In the two-component curing coating agent, the equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate groups of the polyisocyanate (I) contained in the curing agent to the hydroxyl groups of the polyol (P) contained in the base agent is preferably 2.5 or less, more preferably 2.0 or less. By keeping the equivalent ratio (isocyanate group / hydroxyl group) within the above range, it is possible to reduce the decrease in the elongation of the release layer.

[0152] The equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate groups of the polyisocyanate (I) contained in the curing agent to the hydroxyl groups of the polyol (P) contained in the base resin is determined by dividing the number of isocyanate groups in the entire polyisocyanate (I) by the number of hydroxyl groups in the entire polyol (P).

[0153] The polyol (P) contained in the base resin contains multiple types of polyols, such as (meth)acrylic polyols (A) and (B). Therefore, the number of hydroxyl groups in the entire polyol (P) is calculated based on the following formula: Number of hydroxyl groups in the entire polyol (P) = (W1 x H1 / 56100) + (W2 x H2 / 56100) + ... + (W m ×H m / 56100) (in the formula, W m is the content (g) of the mth polyol in the entire polyol (P), and H m is the hydroxyl value (mgKOH / g) of the mth polyol, and m is an integer representing the number of types of polyol.

[0154] The hydroxyl value of the m-th polyol refers to a value obtained by measurement in accordance with 4.2 Method B of JIS K 1557-1:2007 (ISO 14900:2001) "Plastics - Test methods for polyurethane raw polyols - Part 1: Determination of hydroxyl value."

[0155] Polyisocyanate (I) may also contain multiple types of polyisocyanates. Therefore, the number of isocyanate groups in the entire polyisocyanate (I) is calculated based on the following formula: Number of isocyanate groups in the entire polyisocyanate (I) = [W1 x I1 / (42.02 x 100)] + [W2 x I2 / (42.02 x 100)] + ... + [W n ×I n / (42.02×100)] (in the formula, W n is the content (g) of the nth polyisocyanate in the entire polyisocyanate (I), and I n is the content (mass fraction %) of isocyanate groups in the nth polyisocyanate, and n is an integer representing the number of types of polyisocyanate.

[0156] The content of isocyanate groups in the nth polyisocyanate can be measured in accordance with Method 11A of JIS K1603-1:2007 "Plastics - Polyurethane raw material aromatic isocyanate test methods - Part 1: Determination of isocyanate group content."

[0157] (Particles) The two-component curing coating agent preferably further contains particles. Therefore, it is preferable that at least one of the base agent and the curing agent contained in the two-component curing coating agent further contains particles. It is more preferable that the base agent contains particles. By using particles, it is possible to impart an uneven shape to the surface of the release layer, thereby improving the releasability of the release layer. In addition, the uneven shape of the surface of the release layer may be transferred to the surface of the semiconductor package, thereby reducing the occurrence of flow marks caused by the encapsulating resin on the surface of the semiconductor package and improving the appearance of the surface of the semiconductor package.

[0158] Examples of the particles include inorganic particles and resin particles. Examples of the inorganic particles include silica particles, alumina particles, titanium oxide particles, calcium carbonate particles, barium carbonate particles, aluminum silicate particles, aluminum oxide particles, zinc oxide particles, magnesium oxide particles, aluminum hydroxide particles, magnesium hydroxide particles, kaolin particles, clay particles, talc particles, quartz particles, diatomaceous earth particles, perlite particles, and bentonite particles. Examples of the resin particles include acrylic resin particles, urethane resin particles, olefin resin particles, polystyrene resin particles, epoxy resin particles, polyvinylidene fluoride particles, melamine resin particles, polyacrylonitrile resin particles, and silicone resin particles. Among these, resin particles are preferred, and urethane resin particles are more preferred. These particles are less likely to fall off from the release layer. The particles may be used alone or in combination of two or more types.

[0159] The volume average particle diameter of the particles is preferably 1 to 60 μm, more preferably 5 to 30 μm. By setting the volume average particle diameter within the above range, it becomes easier to impart an uneven shape to the surface of the release layer, and the releasability of the release layer can be improved.

[0160] The volume average particle size of the particles can be measured using a laser diffraction particle size distribution analyzer (for example, a product name "SALD2100" manufactured by Shimadzu Corporation) while the particles are dispersed in water.

[0161] The particle content in the two-component curing coating agent is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, per 100 parts by mass of the total amount of the polyol (P) contained in the base agent, the polyisocyanate (I) contained in the curing agent, and the particles. By setting the particle content to 1 part by mass or more, it is possible to impart a sufficient uneven shape to the surface of the release layer. By setting the particle content to 50 parts by mass or less, it is possible to reduce particle detachment from the release layer.

[0162] (Curing Catalyst) The two-component curing coating agent may contain a curing catalyst. Therefore, it is preferable that at least one of the base agent and curing agent contained in the two-component curing coating agent contains a curing catalyst, and it is more preferable that the base agent contains a curing catalyst. Examples of curing catalysts include organometallic compounds such as dibutyltin oxide, tin 2-ethylcaproate, tin octoate, and dibutyltin dilaurate. The curing catalysts may be used alone or in combination of two or more.

[0163] The base material and curing agent of the two-component curing coating agent may contain additives as needed, as long as the physical properties of the two-component curing coating agent are not impaired. Examples of additives include antioxidants, light stabilizers, heat stabilizers, antistatic agents, and antifoaming agents.

[0164] The two-component curing coating agent may contain a solvent. Therefore, at least one of the base agent and the curing agent contained in the two-component curing coating agent may contain a solvent. When the base agent contains a solvent, the solids concentration of the base agent is preferably 10 to 90 mass%, more preferably 20 to 80 mass%. When the curing agent contains a solvent, the solids concentration of the curing agent is preferably 10 to 90 mass%, more preferably 20 to 80 mass%.

[0165] Examples of the solvent include hydrocarbons such as pentane, hexane, heptane, and cyclohexane; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate and butyl acetate. The solvents may be used alone or in combination.

[0166] [Release Sheet] The two-component curing coating agent of the present invention is suitably used for release sheets. Specifically, the release sheet has a support layer and a release layer laminated integrally on one side of the support layer, and a cured film of the two-component curing coating agent of the present invention is suitably used as the release layer of such a release sheet. Below, the release sheet formed using the two-component curing coating agent of the present invention will be described.

[0167] (Support Layer) The release sheet includes a support layer. The support layer preferably includes a synthetic resin. Examples of synthetic resins include polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, olefin resins such as propylene resin and ethylene resin, acrylic resin, triacetyl cellulose, polycarbonate, polyamide resin, polystyrene, and nylon. Among these, polyester resins and olefin resins are preferred because of their excellent heat resistance and elongation, polyester resins are more preferred, and polybutylene terephthalate is more preferred. The synthetic resins may be used alone or in combination of two or more.

[0168] The support layer may further contain additives such as an antistatic agent, a light stabilizer, an inorganic filler, a flame retardant, an antioxidant, a lubricant, an ultraviolet absorber, etc. The thickness of the support layer is not particularly limited, but is preferably 5 to 250 μm, and more preferably 10 to 100 μm.

[0169] A release layer is laminated and integrated onto one surface (front surface) of the support layer, and the other surface (back surface) opposite to the one surface of the support layer may be provided with an uneven shape in order to improve the releasability of the release sheet. As a method for providing an uneven shape, a known method such as an embossing method is used.

[0170] (Release Layer) The release sheet has a release layer laminated integrally on one surface of the support layer, The release layer is a cured film of the above-mentioned two-component curing coating agent of the present invention.

[0171] The release layer is laminated integrally on at least one surface of the support layer, but may be laminated integrally on both one surface (front surface) and the other surface (rear surface) of the support layer. When the release layer is laminated integrally on only one surface of the support layer, the other surface of the support layer may be provided with an uneven shape to improve releasability, as described above.

[0172] The thickness of the release layer is preferably 0.1 to 100 μm, and more preferably 5 to 50 μm. By making the thickness of the release layer 0.1 μm or more, it is possible to impart sufficient releasability to the release layer. By making the thickness of the release layer 100 μm or less, it is possible to maintain the extensibility of the release layer.

[0173] The release sheet may further have another layer between the release layer and the support layer or on the release layer. Examples of the other layer include an adhesive layer, an antistatic layer, and a colored layer. It is preferable that the release sheet further has at least one of these other layers. The adhesive layer is used to improve the adhesion between the release layer and the support layer. It is preferable that the adhesive layer contains a known adhesive such as an olefin-based adhesive, a polyester-based adhesive, an acrylic-based adhesive, or a fluororubber-based adhesive.

[0174] Furthermore, a protective sheet may be releasably laminated and integrated onto the release layer. The protective sheet is used to prevent scratches and dirt from adhering to the release layer during transportation or storage of the release sheet. Therefore, when using the release sheet, it is preferable to peel off and remove the protective sheet to expose the release layer as the outermost layer of the release sheet.

[0175] Examples of the protective sheet include metal foils and resin films. Examples of metal foils include aluminum foils. Examples of resin films include polyethylene terephthalate films, polyethylene films, and polypropylene films. The surface of the protective sheet facing the release layer is preferably subjected to a release treatment.

[0176] As a method for producing a release sheet, a method (i) is used in which the base agent and curing agent of a two-component curing coating agent are mixed, and the two-component curing coating agent is applied to at least one surface of a support layer and heated to form a release layer. It is preferable to mix the base agent and curing agent of the two-component curing coating agent immediately before applying the two-component curing coating agent to at least one surface of the support layer.

[0177] The two-component curing coating agent is applied to at least one surface of the support layer, but the two-component curing coating agent may be applied to only one surface of the support layer, or may be applied to both one surface and the other surface of the support layer. Furthermore, when other layers such as an adhesive layer, an antistatic layer, and a coloring layer are disposed on the support layer, the two-component curing coating agent may be applied to these other layers.

[0178] Examples of methods for applying the two-component curing coating agent include dip coating, spray coating, roll coating, doctor blade coating, and screen printing, as well as casting using a bar coater or applicator.

[0179] The two-component curing coating agent applied to at least one surface of the support layer is then thermally cured by heating, which causes the polyol (P) and polyisocyanate (I) contained in the two-component curing coating agent to react with each other to form polyurethane, thereby curing the two-component curing coating agent and forming a release layer.

[0180] The heating temperature of the two-component curing coating agent is preferably 60 to 180° C., more preferably 80 to 150° C. The heating time of the two-component curing coating agent is preferably 1 to 30 minutes, more preferably 1 to 10 minutes.

[0181] As a method for producing a release sheet, method (ii) can also be used, which includes the steps of mixing the main agent and curing agent of a two-component curing coating agent, applying the two-component curing coating agent to the release-treated surface of the protective sheet, and heating the mixture to form a release layer, and laminating and integrating the release layer onto at least one surface of the support layer.

[0182] In the step of forming the release layer, a two-component curing coating agent is applied to the release-treated surface of the protective sheet and heated, thereby forming a release layer that is releasably laminated and integrated with the protective sheet. In the above method (ii), the method of applying the two-component curing coating agent to the release-treated surface of the protective sheet, and the heating temperature and heating time of the two-component curing coating agent are the same as those in the above method (i), and therefore detailed explanations are omitted here.

[0183] In the step of laminating the release layer onto at least one surface of the support layer, it is preferable to laminate the release layer onto at least one surface of the support layer using an adhesive. As the adhesive, a known adhesive such as an olefin-based adhesive, a polyester-based adhesive, an acrylic-based adhesive, or a fluororubber-based adhesive can be used. This allows the release layer to be laminated onto at least one surface of the support layer via an adhesive layer containing the adhesive.

[0184] The release layer may be laminated integrally on only one surface of the support layer, or may be laminated integrally on both one surface and the other surface of the support layer. In addition, when other layers such as an antistatic layer and a colored layer are disposed on the support layer, the release layer may be laminated integrally on these other layers.

[0185] The release sheet of the present invention is suitable for use as a release sheet for semiconductor packages. A semiconductor package can be obtained, for example, by encapsulating a semiconductor chip with an encapsulating resin in a mold in which the release sheet is placed. When using a release sheet having a release layer only on one side of the support layer, the release sheet is preferably placed in the mold so that the release layer of the release sheet comes into contact with the encapsulating resin. The semiconductor package can be manufactured by either compression molding or transfer molding.

[0186] For example, in the compression molding method, a semiconductor package is manufactured using a mold consisting of a lower mold and an upper mold. Specifically, first, a release sheet is placed on the inner surface of the lower mold, and the release sheet is adhered to the inner surface of the lower mold by vacuum suction or the like. Meanwhile, a semiconductor chip is placed in the upper mold. Next, an encapsulating resin is supplied to the inner surface of the lower mold to which the release sheet is adhered, and then the lower and upper molds are clamped together, and the encapsulating resin is compressed and heated to harden it. This encapsulates the semiconductor chip with the encapsulating resin, resulting in a semiconductor package. The mold is then opened, and the semiconductor package can be removed from the mold. The encapsulating resin is not particularly limited, but a thermosetting resin such as an epoxy resin is preferably used.

[0187] The two-component curing coating agent of the present invention can form a release layer with excellent releasability and extensibility. The release sheet having such a release layer can adhere to the cavity of a mold without tearing during the semiconductor encapsulation process due to the excellent extensibility of the release layer. In particular, even when the inner surface of the mold cavity has a complex shape or a large uneven shape with large height differences, the release sheet can adhere to the inner surface of the mold cavity while conforming to the shape of the inner surface. This reduces contamination of the mold by the encapsulation resin, allowing the production of a semiconductor package with excellent appearance. Furthermore, the excellent release properties of the release layer allow the semiconductor package to be easily removed from the mold without damage after the semiconductor encapsulation process. At this time, the semiconductor package can also be easily peeled from the release sheet.

[0188] The use of the release sheet of the present invention has been described above as an example of a semiconductor package. However, the use of the release sheet is not particularly limited. Other uses of the release sheet include various uses such as a release sheet for molding carbon fiber prepreg or ceramic capacitors, a release film for transferring prints to products, and a release sheet for protecting the adhesive layer of an adhesive film.

[0189] [Transfer Functional Sheet] Furthermore, the release sheet of the present invention can also be used as a transfer functional sheet for imparting a functional layer such as a hard coat layer to a resin molded article.

[0190] The transfer functional sheet has a release sheet and a transfer sheet releasably laminated on the release layer of the release sheet. The transfer sheet includes a hard coat layer and an adhesive layer in this order, and is disposed so that the release layer of the release sheet faces the hard coat layer.

[0191] The release sheet for the transfer functional sheet is the release sheet described above. As described above, the release sheet has a support layer and a release layer laminated and integrated on one surface of the support layer.

[0192] The hard coat layer is used to impart high hardness and scratch resistance to the surface of the resin molded product. The hard coat layer preferably contains a synthetic resin. The synthetic resin is not particularly limited, and examples thereof include polyester-based resins, acrylic-based resins, urethane-based resins, amide-based resins, silicone-based resins, and epoxy-based resins. The synthetic resin may be a curable resin capable of forming a crosslinked structure through a crosslinking reaction. Depending on the type of curing, curable resins are classified into ionizing radiation-curable resins such as ultraviolet-curable resins and electron beam-curable resins, thermosetting resins, and warm air-curable resins. The thickness of the hard coat layer is not particularly limited, and is preferably 0.5 to 30 μm, and more preferably 1 to 10 μm.

[0193] Other functional layers such as a decorative layer or an antistatic layer may be disposed between the hard coat layer and the adhesive layer. That is, the transfer sheet preferably includes a hard coat layer, other functional layers, and an adhesive layer in this order. Among these, the other functional layer is preferably a decorative layer. The decorative layer is used to decorate the resin molded body. Examples of the decorative layer include a printed layer and a metal thin film layer.

[0194] The print layer preferably contains a binder resin and a colorant. Examples of the binder resin include polyvinyl resin, polyester resin, acrylic resin, polyvinyl acetal resin, and cellulose resin. Examples of the colorant include pigments and dyes. Examples of the pigment that can be used include black pigments, metallic pigments, pearl pigments, and fluorescent pigments.

[0195] The printed layer can be produced, for example, by printing a printing ink containing a binder resin and a colorant in a desired printing pattern. The printing pattern may be appropriately determined in consideration of the design to be imparted to the resin molded article, and examples thereof include wood grain, stone grain, cloth grain, sand grain, circles, squares, polygons, geometric patterns, letters, solid printing, etc.

[0196] Examples of metals contained in the metal thin film layer include aluminum, silver, chromium, titanium oxide, and zinc oxide. The metal thin film layer can be formed by a known method such as vacuum deposition, sputtering, or plasma CVD. A fine uneven structure may be formed on the metal thin film layer by embossing to impart a hologram effect.

[0197] A primer layer may be disposed between the hard coat layer and the other functional layer to improve their adhesion. That is, the transfer sheet may include a hard coat layer, a primer layer, the other functional layer, and an adhesive layer in this order. The primer layer preferably includes a binder resin. Examples of binder resins include urethane resins, acrylic resins, (meth)acrylic-urethane copolymers, polyester resins, and butyral resins. The thickness of the primer layer is not particularly limited, but is preferably 0.1 to 10 μm.

[0198] The adhesive layer preferably contains an adhesive having heat-sealing properties. Examples of adhesives include vinyl chloride-vinyl acetate copolymer resins, acrylic resins, polyester resins, and cellulose-based materials such as CMC. The thickness of the adhesive layer is not particularly limited, but is preferably 0.5 to 10 μm.

[0199] After the transfer functional sheet is laminated and integrated onto the surface of the resin molded body via the adhesive layer to obtain a laminate, the release sheet of the transfer functional sheet is peeled off from the laminate, and only the transfer sheet of the transfer functional sheet is transferred, thereby obtaining a resin molded body provided with a functional layer such as a hard coat layer.

[0200] The surface of a resin molded product often has a complex three-dimensional shape depending on the application. On the other hand, the transfer functional sheet has excellent extensibility because it contains the release sheet of the present invention. Therefore, even when a resin molded product having a complex three-dimensional shape is used, the transfer functional sheet can be adhered to the surface of the resin molded product while sufficiently conforming to the three-dimensional shape of the resin molded product. Furthermore, the release layer contained in the release sheet of the transfer functional sheet has excellent releasability. Therefore, when the release sheet is peeled from the laminate, the interface between the release layer and the hard coat layer can be easily separated, and the release sheet can be easily peeled from the laminate without damaging it.

[0201] The transfer functional sheet can be transferred to a resin molded body by a known thermal transfer method such as heat press molding, vacuum molding, pressure molding, vacuum pressure molding, in-mold molding, etc. Among these, in-mold molding is preferred.

[0202] In the in-mold molding method, first, a transfer functional sheet is placed in the mold of an injection molding machine so that its adhesive layer is inside the mold of the injection molding machine. Next, a molten resin is injected into the mold of the injection molding machine and then cooled and solidified, thereby obtaining a laminate having a resin molded body having a desired shape and a transfer functional sheet laminated and integrated onto the surface of this resin molded body via the adhesive layer. Then, the release sheet of the transfer functional sheet is peeled off from the laminate. This allows only the transfer sheet of the transfer functional sheet to be transferred, resulting in a resin molded body provided with a functional layer such as a hard coat layer.

[0203] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0204] [Synthesis of (meth)acrylic polyol (A)] (Synthesis Examples A1 to A5) A reaction vessel was charged with 233 parts by mass of methyl isobutyl ketone (MIBK) as a solvent, and the temperature was raised to 80°C. Next, 100 parts by mass of a monomer composition containing methyl methacrylate (MMA), n-butyl acrylate (n-BA), 2-hydroxyethyl acrylate (2-HEA), and α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane (number average molecular weight (Mn) 10,000, manufactured by JNC Corporation, trade name "Silaplane (registered trademark) FM-0725") was mixed with 4.0 parts by mass of azobis-2-methylbromonitrile (manufactured by Nippon Hydrazine Industrial Co., Ltd., trade name "ABN-E") as a polymerization catalyst, to prepare a monomer mixture. Next, the monomer mixture was added dropwise to the above solvent over 3 hours, and the reaction was terminated after a further 3 hours. As a result, a (meth)acrylic polyol solution (solid content: 30% by mass) containing the (meth)acrylic polyol (A) was obtained.

[0205] The amounts of each monomer in the monomer composition were adjusted so as to obtain a (meth)acrylic polyol (A) containing methyl methacrylate units, n-butyl acrylate units, 2-hydroxyethyl acrylate units, and α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane units in the amounts (mass%) shown in Table 1.

[0206] The obtained (meth)acrylic polyol (A) contains a structural unit (S1) having a siloxane bond represented by the above formula (1) (in the above formula (1), R 1 and R 2 and each independently represents a methyl group. The content of the structural unit (S1) in the (meth)acrylic polyol (A) is shown in Table 1.

[0207] [Synthesis of (meth)acrylic polyol (B)] (Synthesis Examples B1 to B6) A reaction vessel was charged with 233 parts by mass of methyl isobutyl ketone (MIBK) as a solvent, and the temperature was raised to 80°C. Next, 100 parts by mass of a monomer composition containing n-butyl acrylate (n-BA), 2-hydroxyethyl acrylate (2-HEA), and α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane (number average molecular weight (Mn) 10,000, manufactured by JNC Corporation under the trade name "Silaplane (registered trademark) FM-0725") was mixed with 4.0 parts by mass of azobis-2-methylbromonitrile (manufactured by Nippon Hydrazine Industrial Co., Ltd. under the trade name "ABN-E") as a polymerization catalyst, to prepare a monomer mixture. Next, the monomer mixture was added dropwise to the solvent over 3 hours, and the reaction was terminated after a further 3 hours. As a result, a (meth)acrylic polyol solution (solid content: 30% by mass) containing the (meth)acrylic polyol (B) was obtained.

[0208] The amounts of each monomer in the monomer composition were adjusted so as to obtain a (meth)acrylic polyol (B) containing n-butyl acrylate units, 2-hydroxyethyl acrylate units, and α-butyl-ω-(3-methacryloxypropyl)polydimethylsiloxane units in the contents (mass%) shown in Table 2.

[0209] The obtained (meth)acrylic polyol (B) contains a structural unit (S1) having a siloxane bond represented by the above formula (1) (in the above formula (1), R 1 and R 2 and each independently represents a methyl group. The content of the structural unit (S1) in the (meth)acrylic polyol (B) is shown in Table 2.

[0210] Synthesis of Polyisocyanate (D) Having Structural Unit (S2) (Synthesis Example C) A reaction vessel was charged with 150 parts by mass of methyl isobutyl ketone (MIBK) as a solvent, 21.7 parts by mass of a polyisocyanate not having the structural unit (S2) (an isocyanurate of hexamethylene diisocyanate, manufactured by Asahi Kasei Corporation under the trade name "Duranate (registered trademark) TKA-100", NCO content: 21.6% by mass), and 0.1 part by mass of dibutyltin dilaurate as a reaction catalyst.

[0211] Next, a polyol (R 14 and R 17 is an ethylene group, and R 15 and R 16 A polyol represented by the above formula (5), in which m is an n-propylene group and m is an integer of 2 or greater, having a number average molecular weight (Mn) of 5,000 and manufactured by JNC Corporation under the trade name "Silaplane (registered trademark) FM-4421" (78.2 parts by mass [equivalent ratio (isocyanate group / hydroxyl group) of 3.0] was added dropwise to the reaction vessel over one hour, and the urethanization reaction was terminated after a further three hours. This yielded a polyisocyanate solution (solids content 40% by mass) containing polyisocyanate (D) having structural unit (S2) (NCO group content 5.0 wt %, structural unit (S2) content 77.3% by mass).

[0212] The polyisocyanate (D) contains a structural unit (S) having a siloxane bond represented by the above formula (4) (in the above formula (4), R 12 and R 13 each independently represents a methyl group).

[0213] (Examples 1 to 10 and 13 to 19, Comparative Examples 1 to 4) (Meth)acrylic polyols (A) obtained in Synthesis Examples A1 to A5, (meth)acrylic polyols (B) obtained in Synthesis Examples B1 to B6, polycaprolactone triol (manufactured by Daicel Corporation, trade name "PLACCEL 303", hydroxyl value 538 mg KOH / g), polycaprolactone diol (manufactured by Daicel Corporation, trade name "PLACCEL 210", hydroxyl value 113 mg KOH / g), polytetramethylene ether glycol (manufactured by Mitsubishi Chemical Corporation, trade name "PTMG-1000"), and polycarbonate diol (manufactured by UBE Co., Ltd., trade name "PTMG-1000") were used. 100 parts by mass of polyol (P) containing polyol (P) having a content (mass %) shown in Tables 3 to 5, 0.1 parts by mass of dibutyltin dilaurate as a curing catalyst, 4.6 parts by mass of methyl isobutyl ketone as a solvent, and 1.7 parts by mass of acetylacetone were supplied to a reaction vessel (I) and mixed to obtain a main component (solid content 40% by mass).

[0214] For the (meth)acrylic polyols (A) obtained in Synthesis Examples A1 to A5, a (meth)acrylic polyol solution containing the (meth)acrylic polyol (A) was supplied to the reaction vessel (I) so that each (meth)acrylic polyol (A) had a content (solid content) shown in Tables 3 to 5. For the (meth)acrylic polyols (B) obtained in Synthesis Examples B1 to B6, a (meth)acrylic polyol solution containing the (meth)acrylic polyol (B) was supplied to the reaction vessel (I) so that each (meth)acrylic polyol (B) had a content (solid content) shown in Tables 3 to 5.

[0215] The contents (% by mass) of the (meth)acrylic polyol (A), the (meth)acrylic polyol (B), the polycaprolactone triol, and the polycaprolactone diol in the main polyol (P) are shown by the numerical values ​​not enclosed in parentheses in the "Main Component" column of Tables 3 to 5.

[0216] The content of the structural unit (S1) in the (meth)acrylic polyol (A) is shown by a numerical value enclosed in parentheses in the column for "(meth)acrylic polyol (A)" in Tables 3 to 5. The content of the structural unit (S1) in the (meth)acrylic polyol (B) is shown by a numerical value enclosed in parentheses in the column for "(meth)acrylic polyol (B)" in Tables 3 to 5.

[0217] Next, 100 parts by mass of polyisocyanate (I) containing polyisocyanate (C) not containing the structural unit (S2) (a bifunctional polyurethane diisocyanate which is an adduct of a diol not containing the structural unit (S2) and hexamethylene diisocyanate, manufactured by Asahi Kasei Corporation under the trade name "Duranate D-201", NCO content 15.8 wt%), and polyisocyanate (D) containing the structural unit (S2) obtained in Synthesis Example C, respectively, in the amounts shown in Tables 3 to 5, 0.1 parts by mass of dibutyltin dilaurate as a curing catalyst, 120 parts by mass of methyl isobutyl ketone as a solvent, and 3.6 parts by mass of acetylacetone were supplied to a reaction vessel (II) and mixed to obtain a curing agent (solids content 40% by mass). This resulted in a two-component curing coating agent containing the base agent and the curing agent.

[0218] For the polyisocyanate (D) having the structural unit (S2) obtained in Synthesis Example C, a polyisocyanate solution containing the polyisocyanate (D) having the structural unit (S2) was supplied to the reaction vessel (II) so that the content (solid content) of the polyisocyanate (D) having the structural unit (S2) was as shown in Tables 3 to 5.

[0219] The contents (mass%) of the polyisocyanate (C) not having the structural unit (S2) and the polyisocyanate (D) having the structural unit (S2) in the polyisocyanate (I) as the curing agent are shown by the numerical values ​​not enclosed in parentheses in the "Curing Agent" column of Tables 3 to 5.

[0220] Furthermore, the content of the structural unit (S2) in the polyisocyanate (I) is shown in the "Curing agent" column of Tables 3 to 5 by a numerical value enclosed in parentheses.

[0221] Next, the curing agent was added to the base agent and mixed so that the equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate group of the polyisocyanate (I) contained in the curing agent to the hydroxyl group of the polyol (P) contained in the base agent was the value shown in Tables 3 to 5. Thereafter, the two-component curing coating agent was immediately applied to one surface of a support layer (polybutylene terephthalate film, thickness 50 μm, manufactured by Okura Kogyo Co., Ltd., product name "ESRM") and heated at 120°C for 5 minutes to remove the solvent and thermally cure the layer, forming a release layer (thickness 20 μm) on one surface of the support layer. This resulted in a release sheet having a support layer and a release layer laminated and integrated onto one surface of the support layer.

[0222] Examples 11 and 12 A base resin, a curing agent, and a release sheet were produced in the same manner as in Example 5, except that silica particles (volume average particle diameter: 10 μm) or urethane resin particles (volume average particle diameter: 10 μm) were further supplied to the reaction vessel (I) during the preparation of the base resin.

[0223] The content ratio of silica particles or urethane resin particles relative to 100 parts by mass of the total amount of the polyol (P) contained in the base agent, the polyisocyanate (I) contained in the curing agent, and particles in the two-component curing coating agent was the value shown in Table 3 or 4.

[0224] [Evaluation] The release sheets obtained in the examples and comparative examples were evaluated for elongation, releasability, bleed-out resistance, and particle shedding resistance according to the following procedures. The results are shown in Tables 3 to 5.

[0225] (Elongation) In accordance with JIS K7127 (Plastics - Testing methods for tensile properties), the release sheet was cut into the shape of a type 2 test piece, and the elongation (%) was measured using a tensile tester (manufactured by Shimadzu Corporation, product name "Autograph AGS-X") at a tensile speed of 50 mm / min. The elongation was then evaluated according to the following evaluation criteria. [Evaluation criteria] A: The elongation was 200% or more. B: The elongation was 150% or more and less than 200%. C: The elongation was 50% or more and less than 150%. F: The elongation was less than 50%.

[0226] (Release Property) An aluminum foil tape (manufactured by Nitto Denko Corporation, product name "Nitofoil AT-50") having an aluminum foil and an adhesive layer made of an acrylic adhesive was prepared. The aluminum foil tape was attached to the release layer surface of the release sheet so that the release layer and the adhesive layer were in contact. This state was left to stand at room temperature for 24 hours to obtain an evaluation sheet. Thereafter, the aluminum foil tape was peeled from the evaluation sheet, and the peel strength was measured using a peel tester (manufactured by Tester Sangyo, product name "TE-1003"). The peel angle was 180 degrees, and the peel speed was 300 mm / min. The peel strength was evaluated according to the following criteria. [Evaluation Criteria] A: The peel strength was less than 1.5 N / 2.5 cm. B: The peel strength was 1.5 N / 2.5 cm or more and less than 2.5 N / 2.5 cm. C: The peel strength was 2.5 N / 2.5 cm or more and less than 3.5 N / 2.5 cm. F: The peel strength was 3.5 N / 2.5 cm or more.

[0227] (Bleed-out Resistance) A PET film (50 μm, manufactured by Toyobo Co., Ltd., trade name Cosmoshine A4160) was placed on the release layer of the release sheet, and the resulting sheet was pressed at 175° C. with a pressing pressure of 80 kg / cm using a hot press. 2 The mixture was hot pressed for 5 minutes under the conditions:

[0228] Thereafter, the PET film was peeled from the release layer, and one 2 μL droplet of distilled water was dropped on the portion of the PET film surface that had been in contact with the release layer, and the contact angle A1 (°) between the PET film surface and the distilled water droplet was measured using an automatic contact angle meter (manufactured by Kyowa Interface Science, trade name "DMs-601"). Note that the "contact angle" is the angle θ that includes the distilled water droplet W, among the angles formed by the tangent L of the distilled water droplet at the end point P of the interface between the distilled water droplet W and the PET film surface S and the PET film surface S, as shown in FIG.

[0229] Then, in the same manner as above, one 2 μL droplet of distilled water was dropped onto the surface of the PET film before hot pressing, and the contact angle A0 (°) between the PET film surface and the distilled water droplet was measured. The difference X in contact angles was calculated based on the following formula and evaluated according to the following evaluation criteria: Contact angle difference X (°) = [Contact angle A1 (°)] - [Contact angle A0 (°)] [Evaluation criteria] A: The contact angle difference X was less than 3°. B: The contact angle difference X was 3° or more and less than 6°. C: The contact angle difference X was 6° or more and less than 11°. F: The contact angle difference X was 11° or more.

[0230] The larger the difference X in contact angles, the higher the hydrophobicity of the PET film surface after hot pressing. This is thought to be because, due to hot pressing, components having siloxane bonds (e.g., (meth)acrylic polyol (B) and polyisocyanate (D) having the structural unit (S2)) contained in the release layer bleed out to the surface of the release layer and migrate to the PET film, thereby increasing the hydrophobicity of the PET film surface. Therefore, the smaller the difference X in contact angles, the lower the hydrophobicity of the PET film surface is maintained, and the less bleed-out of components having siloxane bonds is reduced, meaning that the PET film has excellent bleed-out resistance.

[0231] (Particle Fall-Off Resistance) A release sheet was placed between the upper and lower molds of a semiconductor encapsulation compression molding device (FFT-1030), and then the release sheet was adhered to the parting surface of the lower mold by vacuum suction. A semiconductor chip fixed to a substrate was placed on the parting surface of the upper mold. Next, encapsulating resin was poured into the cavity of the lower mold with the release sheet adhered to the parting surface, and the mold temperature was heated to 175°C to melt the encapsulating resin. Then, the upper and lower molds were clamped together, and air was removed from the vacuum suction holes around the cavity using a vacuum pump. Compression molding was then performed under the following encapsulation conditions, and the semiconductor element fixed to the substrate was encapsulated with the encapsulating resin to obtain a semiconductor package. The semiconductor package was then released from the mold and release sheet and removed.

[0232] <Sealing conditions> Mold temperature: 175°C Cavity size: 220 mm x 54 mm Cavity depth: 0.8 mm Sealing resin: thermosetting epoxy resin Molding time: 120 seconds Molding pressure: 80 kg / cm 2

[0233] The surface of the sealing resin portion of the removed semiconductor package that had been in contact with the release sheet was used as the measurement surface. This measurement surface was observed using a scanning electron microscope (SEM) at a measurement magnification of 100x, and the number of particles adhering to the measurement surface was counted. Using the same procedure, the number of particles adhering to 10 arbitrary locations on the measurement surface was counted, and the arithmetic mean value was taken as the "average particle number," which was evaluated according to the following evaluation criteria. [Evaluation Criteria] A: The average number of particles adhering was less than 10. B: The average number of particles adhering was 10 or more but less than 100. F: The average number of particles adhering was 100 or more.

[0234] The resistance to particle shedding was measured only for the release sheets of Examples 11 and 12, whose release layers contained silica particles or urethane resin particles. The particles adhering to the measurement surface of the semiconductor package were silica particles or urethane resin particles that had fallen off from the release layer of the release sheet.

[0235]

[0236]

[0237]

[0238]

[0239]

[0240] The two-component curable coating agent for release sheets of the present invention can form a release layer that is excellent in both releasability and elongation. A release sheet having such a release layer is suitable for use in the production of resin molded products such as semiconductor packages. The release sheet can easily remove resin molded products such as semiconductor packages from the inner surface of a mold, and can reduce the occurrence of poor appearance in the resin molded products due to wrinkles or breakage of the release sheet.

[0241] (Cross-reference to related applications) This application claims priority to Japanese Patent Application No. 2023-191499, filed November 9, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0242] S: PET film surface W: distilled water droplet L: tangent to the distilled water droplet P: end point of the interface between the distilled water droplet W and the PET film surface S

Claims

1. A two-component curing coating agent for release sheets, comprising a base agent containing a polyol (P) and a curing agent containing a polyisocyanate (I), wherein the polyol (P) comprises: a (meth)acrylic polyol (A) having a content of structural units (S1) having siloxane bonds as shown in the following formula (1) that is greater than 0% by mass and less than 12% by mass; and a (meth)acrylic polyol (B) having a content of structural units (S1) having siloxane bonds as shown in the following formula (1) that is 12% by mass or more and 30% by mass or less. (In formula (1), R 1 and R 2 each independently represents a hydrogen atom or a monovalent hydrocarbon group, and * represents a bond.

2. The two-component curing coating agent for release sheets according to claim 1, characterized in that the polyol (P) further comprises at least one polyol selected from the group consisting of polyester polyols, polyether polyols, polycarbonate polyols, and alkyl polyols.

3. The two-component curing coating agent for release sheets according to claim 1, characterized in that the polyisocyanate (I) contains 0.5 mass % or more and 40 mass % or less of a structural unit (S2) having a siloxane bond represented by the following formula (4). (In formula (4), R 12 and R 13 each independently represents a hydrogen atom or a monovalent hydrocarbon group, and * represents a bond.

4. The two-component curing coating agent for release sheets according to claim 1, characterized in that at least one of the base agent and the curing agent further contains particles.

5. The two-component curing coating agent for release sheets according to claim 4, characterized in that the particles contain urethane resin particles.

6. A release sheet comprising: a support layer; and a release layer which is integrally laminated on one surface of the support layer and which is a cured film of the two-component curing coating agent for release sheets according to claim 1.