Adhesive sheet and method for manufacturing the same

Abstract

To provide an adhesive sheet which exhibits good adhesive force to both a high polar material and a low polar material while containing carbon dioxide as a production raw material, and is excellent in retention force.SOLUTION: Adhesive sheets 1A and 1B have an adhesive layer 11 composed of an adhesive containing 50 mass% or more of an aliphatic polycarbonate resin having an ether structure in the main chain and a crosslinkable functional group in the side chain, wherein adhesive force to polypropylene is 1.5 N / 25 mm or more; and adhesive sheets 1A and 1B have an adhesive layer 11 composed of an adhesive containing 50 mass% or more of an aliphatic polycarbonate resin crosslinked body that is a crosslinked body of an aliphatic polycarbonate resin having an ether structure in the main chain and a crosslinkable functional group in the side chain, wherein adhesive force to polypropylene is 1.5 N / 25 mm or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet using an aliphatic polycarbonate resin as the pressure-sensitive adhesive. [Background technology]

[0002] Acrylic adhesives containing acrylic polymers as the main component have been widely used as adhesives. Acrylic polymers are typically produced by polymerizing monomers primarily consisting of (meth)acrylic acid alkyl esters having alkyl groups with 2 to 12 carbon atoms.

[0003] The above-mentioned acrylic adhesives exhibit good adhesive strength to materials (high-polarity materials) with highly polar surfaces such as glass, polycarbonate resin, and acrylic resin, but are unlikely to exhibit good adhesive strength to materials (low-polarity materials) with low-polarity surfaces such as polyolefin resins such as polyethylene and polypropylene.

[0004] Therefore, tackifying resins have been added to acrylic adhesives to improve their adhesive strength to low-polarity materials. However, improving adhesive strength to low-polarity materials tends to reduce adhesive strength to high-polarity materials, and it has not been easy to achieve adhesive strength to both materials. In addition to adhesive strength, holding power is also an important factor in adhesive properties.

[0005] Therefore, Patent Document 1 proposes a photopolymerizable composition that is photopolymerized by ultraviolet light and contains a monomer mainly composed of a (meth)acrylic acid alkyl ester having an alkyl group of 2 to 12 carbon atoms, a tackifier resin, and a photopolymerization initiator, in which the tackifier resin is composed of a hydrogenated alicyclic hydrocarbon resin having a predetermined amount of hydroxyl groups and a hydrogenated non-polar alicyclic hydrocarbon resin.

[0006] In recent years, with the growing demand for the creation of a recycling-oriented society, gases such as carbon dioxide, methane, and carbon monoxide have been attracting attention as sustainable carbon raw materials. For example, it has been reported that aliphatic polycarbonates, which have only aliphatic (non-aromatic) groups in their main chains, can be produced by copolymerizing carbon dioxide with epoxides. This has led to interest in chemical products and their manufacturing technologies that use gases such as carbon dioxide as raw materials.

[0007] Carbon dioxide is believed to be a cause of global warming, so the effective use of carbon dioxide emitted from factories in the process of producing various materials will help protect the environment.

[0008] Patent Document 2 proposes a polyalkylene carbonate resin containing three types of repeating units obtained by copolymerizing an epoxide compound, a compound having an epoxy group and an acrylate structure, and carbon dioxide in the presence of a heterogeneous catalyst. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-96116 [Patent Document 2] Special Publication No. 2015-533920 Summary of the Invention [Problem to be solved by the invention]

[0010] The invention described in Patent Document 2 aims to provide a polyalkylene carbonate resin that exhibits thermal stability and mechanical properties such as a larger molecular weight and improved strength. Conventional polycarbonate resins, including this polyalkylene carbonate resin, have a high glass transition temperature (Tg) due to the rigidity of their polycarbonate structure, making them unsuitable as pressure-sensitive adhesives.

[0011] The present invention has been made in consideration of these circumstances, and aims to provide an adhesive sheet that uses carbon dioxide as a manufacturing raw material, exhibits good adhesive strength to both high-polarity and low-polarity materials, and also has excellent holding power. [Means for solving the problem]

[0012] In order to achieve the above object, first, the present invention provides an adhesive sheet having an adhesive layer made of an adhesive containing 50 mass % or more of an aliphatic polycarbonate resin having an ether structure in the main chain and a crosslinkable functional group in the side chain, and having an adhesive strength to polypropylene of 1.5 N / 25 mm or more (Invention 1).

[0013] The pressure-sensitive adhesive sheet according to the above invention (Invention 1) has the above-mentioned configuration and physical properties, and therefore exhibits good adhesive strength to both high-polarity and low-polarity materials, and also has excellent holding power.

[0014] Secondly, the present invention provides a pressure-sensitive adhesive sheet having an adhesive layer made of a pressure-sensitive adhesive containing 50% by mass or more of a crosslinked aliphatic polycarbonate resin, which is a crosslinked aliphatic polycarbonate resin having an ether structure in the main chain and a crosslinkable functional group in the side chain, and having an adhesive strength to polypropylene of 1.5 N / 25 mm or more (Invention 2).

[0015] The pressure-sensitive adhesive sheet according to the above invention (Invention 2), having the above-mentioned configuration and physical properties, exhibits good adhesive strength to both high-polarity and low-polarity materials and has excellent holding power. In particular, since the crosslinked aliphatic polycarbonate resin is obtained by crosslinking the aliphatic polycarbonate resin, it has good cohesion, resulting in even better adhesive strength and holding power.

[0016] In the above invention (Invention 2), the holding power conforming to JIS Z0237:2009 is preferably such that the time it takes for the adhesive sheet to fall is 8000 seconds or longer when the adherend is made of stainless steel, the adhesive area is 25 mm x 25 mm, the test temperature is 40°C, and a load of 9.8 N is applied (Invention 3).

[0017] In the above inventions (Inventions 1 to 3), it is preferable that the aliphatic polycarbonate resin has an ether structure in its main chain and has a structure in which a repeating unit represented by the following formula (Ia), a repeating unit represented by the following formula (Ib), a repeating unit represented by the following formula (Ic), and a repeating unit represented by the following formula (Id) are randomly copolymerized (Invention 4). [ka] (In formula (Ia) and formula (Ib), R 1 and R 2 are hydrogen atoms or hydrocarbon groups, and may be the same or different. 3 and R 4 are hydrocarbon groups having a crosslinkable functional group, and may be the same or different.

[0018] In the above inventions (Inventions 1 to 4), the crosslinkable functional group is preferably a (meth)acryloyl group or an allyl group (Invention 5).

[0019] In the above inventions (Inventions 4 and 5), the R 3 or the above R 4 However, it is preferable that the alkyl chain is present (Invention 6).

[0020] In the above inventions (Inventions 4 to 6), the R 3 or the above R 4 However, it is preferable that the compound has an ether structure (Invention 7).

[0021] In the above inventions (Inventions 4 to 7), the R 3 or the above R4 It is preferable that the compound contains a structure represented by the following general formula (II) (Invention 8). CH2=CH-C(=O)-OXO- (II) (In formula (II), X is an alkyl chain.)

[0022] In the above inventions (Inventions 1 to 8), the aliphatic polycarbonate resin preferably contains the crosslinkable functional group in an amount of 0.01 mol % or more and 10 mol % or less (Invention 9).

[0023] In the above inventions (Inventions 1 to 9), the aliphatic polycarbonate resin preferably contains 0.1 mass % or more and 99 mass % or less of the ether structure unit in the main chain (Invention 10).

[0024] In the above inventions (Inventions 1 to 10), the glass transition temperature (Tg) of the aliphatic polycarbonate resin is preferably 5° C. or lower (Invention 11).

[0025] In the above invention (Invention 2), the 5% weight loss temperature of the crosslinked aliphatic polycarbonate resin is preferably 200° C. or higher and 450° C. or lower (Invention 12).

[0026] In the above invention (Invention 2), the gel fraction of the crosslinked aliphatic polycarbonate resin is preferably 15% or more and 85% or less (Invention 13). [Effects of the Invention]

[0027] The pressure-sensitive adhesive sheet according to the present invention is made from carbon dioxide as a raw material, and exhibits good adhesive strength to both highly polar and less polar materials, and also has excellent holding power. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. [Figure 2] FIG. 4 is a cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. [Figure 3] 1 is a chart showing the results of 1H-NMR measurement of the polymer produced in Example 1. [Figure 4] 1 is a chart showing the results of 1H-NMR measurement of the polymer produced in Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, an embodiment of the present invention will be described. The pressure-sensitive adhesive sheet according to the first embodiment of the present invention comprises a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive containing 50% by mass or more of an aliphatic polycarbonate resin having an ether structure in its main chain and a crosslinkable functional group in its side chain (hereinafter sometimes referred to as "aliphatic polycarbonate resin A"), and has an adhesive strength to polypropylene of 1.5 N / 25 mm or more. Note that the specific test method for adhesive strength in this specification is as shown in the test examples described below.

[0030] Furthermore, the adhesive sheet according to the second embodiment of the present invention comprises an adhesive layer made of an adhesive containing 50% by mass or more of a crosslinked aliphatic polycarbonate resin (hereinafter sometimes referred to as "crosslinked aliphatic polycarbonate resin B"), which is a crosslinked aliphatic polycarbonate resin (aliphatic polycarbonate resin A) having an ether structure in its main chain and a crosslinkable functional group in its side chain, and has an adhesive strength to polypropylene of 1.5 N / 25 mm or more.

[0031] In the pressure-sensitive adhesive sheet according to the first embodiment, the pressure-sensitive adhesive layer is made of a pressure-sensitive adhesive containing 50% by mass or more of the aliphatic polycarbonate resin A and has the above-mentioned adhesive strength, thereby exhibiting good adhesive strength to both high-polarity and low-polarity materials and excellent holding power. Furthermore, in the pressure-sensitive adhesive sheet according to the second embodiment, the pressure-sensitive adhesive layer is made of a pressure-sensitive adhesive containing 50% by mass or more of the aliphatic polycarbonate resin crosslinked product B and has the above-mentioned adhesive strength, thereby exhibiting good adhesive strength to both high-polarity and low-polarity materials and excellent holding power. In particular, since the aliphatic polycarbonate resin crosslinked product B is obtained by crosslinking the aliphatic polycarbonate resin A, it has good cohesion, resulting in even better adhesive strength and holding power.

[0032] As will be described later, the aliphatic polycarbonate resin A and the crosslinked aliphatic polycarbonate resin B can be produced using carbon dioxide as a production raw material. Therefore, in the production of the pressure-sensitive adhesive sheets according to the first and second embodiments, carbon dioxide can be effectively utilized.

[0033] Here, examples of high-polarity materials (materials having a high-polarity surface) include metals such as stainless steel, aluminum, and copper; glass; and resins such as polycarbonate resin, acrylic resin, and polyethylene terephthalate resin. Examples of low-polarity materials (materials having a low-polarity surface) include polyolefin resins such as polyethylene and polypropylene, polyacetal resin, and polytetrafluoroethylene resin.

[0034] The adhesive strength of the pressure-sensitive adhesive sheet according to the first embodiment to polypropylene is at least 1.5 N / 25 mm as a lower limit, preferably at least 3 N / 25 mm, particularly preferably at least 5 N / 25 mm, and even more preferably at least 7 N / 25 mm. On the other hand, the upper limit of the adhesive strength is not particularly limited, but taking into consideration cases where reworkability is required, it is preferably at most 25 N / 25 mm, particularly preferably at most 20 N / 25 mm, and even more preferably at most 15 N / 25 mm.

[0035] The adhesive strength of the pressure-sensitive adhesive sheet according to the first embodiment to stainless steel (SUS304, polished #360) is preferably 1 N / 25 mm or more, more preferably 5 N / 25 mm or more, particularly preferably 7 N / 25 mm or more, and even more preferably 10 N / 25 mm or more, as a lower limit. Thus, the pressure-sensitive adhesive sheet according to the first embodiment can exhibit good adhesive strength even to highly polar materials. Meanwhile, while there are no particular limitations on the upper limit of the adhesive strength, taking into consideration cases where reworkability is required, it is preferably 45 N / 25 mm or less, particularly preferably 40 N / 25 mm or less, and even more preferably 30 N / 25 mm or less.

[0036] The adhesive strength of the pressure-sensitive adhesive sheet according to the first embodiment to polycarbonate is preferably 3 N / 25 mm or more, more preferably 5 N / 25 mm or more, particularly preferably 7 N / 25 mm or more, and even more preferably 10 N / 25 mm or more, as a lower limit. Thus, the pressure-sensitive adhesive sheet according to the first embodiment can exhibit good adhesive strength even to highly polar materials. Meanwhile, the upper limit of the adhesive strength is not particularly limited, but taking into consideration cases where reworkability is required, it is preferably 40 N / 25 mm or less, particularly preferably 30 N / 25 mm or less, and even more preferably 25 N / 25 mm or less.

[0037] The adhesive sheet according to the first embodiment has a holding power (seconds) in accordance with JIS Z0237:2009 (the time (maximum 70,000 seconds) until the adhesive sheet falls when the adherend is stainless steel (SUS304, #360 polished), the adhesion area is 25 mm x 25 mm, the test temperature is 40°C, and a load of 9.8 N is applied) of preferably 1,000 seconds or more, more preferably 2,000 seconds or more, particularly preferably 3,000 seconds or more, and even more preferably 4,000 seconds or more. The adhesive sheet according to the first embodiment can exhibit excellent holding power as described above. The specific test method for holding power in this specification is as shown in the test examples described below.

[0038] The adhesive sheet according to the second embodiment has a lower limit of adhesive strength to polypropylene of 1.5 N / 25 mm or more, preferably 3 N / 25 mm or more, particularly preferably 5 N / 25 mm or more, and even more preferably 7 N / 25 mm or more. On the other hand, the upper limit of the adhesive strength is not particularly limited, but taking into consideration cases where reworkability is required, it is preferably 25 N / 25 mm or less, particularly preferably 20 N / 25 mm or less, and even more preferably 15 N / 25 mm or less.

[0039] The adhesive strength of the pressure-sensitive adhesive sheet according to the second embodiment to stainless steel (SUS304, polished #360) is preferably 1 N / 25 mm or more, more preferably 3 N / 25 mm or more, particularly preferably 5 N / 25 mm or more, and even more preferably 10 N / 25 mm or more, as a lower limit. Thus, the pressure-sensitive adhesive sheet according to the second embodiment can exhibit good adhesive strength even to highly polar materials. Meanwhile, the upper limit of the adhesive strength is not particularly limited, but taking into consideration cases where reworkability is required, it is preferably 30 N / 25 mm or less, particularly preferably 25 N / 25 mm or less, and even more preferably 20 N / 25 mm or less.

[0040] The adhesive strength of the pressure-sensitive adhesive sheet according to the second embodiment to polycarbonate is preferably 1 N / 25 mm or more, more preferably 2 N / 25 mm or more, particularly preferably 5 N / 25 mm or more, and even more preferably 10 N / 25 mm or more, as a lower limit. Thus, the pressure-sensitive adhesive sheet according to the second embodiment can exhibit good adhesive strength even to highly polar materials. Meanwhile, the upper limit of the adhesive strength is not particularly limited, but taking into consideration cases where reworkability is required, it is preferably 35 N / 25 mm or less, particularly preferably 30 N / 25 mm or less, and even more preferably 25 N / 25 mm or less.

[0041] The adhesive sheet according to the second embodiment has a holding power (seconds) according to JIS Z0237:2009 (the time (maximum 70,000 seconds) until the adhesive sheet falls when the adherend is stainless steel (SUS304, #360 polished), the applied area is 25 mm x 25 mm, the test temperature is 40°C, and a load of 9.8 N is applied) of preferably 8,000 seconds or more, more preferably 10,000 seconds or more, particularly preferably 30,000 seconds or more, and even more preferably 70,000 seconds or more. The adhesive sheet according to the second embodiment can exhibit excellent holding power as described above.

[0042] 1. Adhesive (1) Adhesive in the First Embodiment The adhesive constituting the adhesive layer in the adhesive sheet according to the first embodiment contains 50% by mass or more of aliphatic polycarbonate resin A. Aliphatic polycarbonate resin A has an ether structure in its main chain and crosslinkable functional groups in its side chains, and preferably has an ether structure in its main chain and a structure in which repeating units represented by the following formula (Ia), repeating units represented by the following formula (Ib), repeating units represented by the following formula (Ic), and repeating units represented by the following formula (Id) are randomly copolymerized (hereinafter sometimes referred to as "structure SA"). [ka] (In formula (Ia) and formula (Ib), R 1 and R 2 are hydrogen atoms or hydrocarbon groups, and may be the same or different. 3 and R 4 are hydrocarbon groups having a crosslinkable functional group, and may be the same or different.

[0043] The aliphatic polycarbonate resin A having the above structure SA can effectively constitute an aliphatic polycarbonate resin having an ether structure in the main chain and a crosslinkable functional group in the side chain.

[0044] R in formula (Ia) and formula (Ib) 1 and R 2 As described above, is a hydrogen atom or a hydrocarbon group. Examples of the hydrocarbon group include alkyl groups and aryl groups such as phenyl groups, with alkyl groups being preferred. The alkyl group preferably has 1 to 20 carbon atoms, more preferably 2 to 18 carbon atoms, particularly preferably 4 to 10 carbon atoms, and even more preferably 6 to 9 carbon atoms. In the aliphatic polycarbonate resin A having the above structure SA, if the hydrocarbon group (hydrocarbon group in the side chain) has a large number of carbon atoms and is relatively long, the glass transition temperature (Tg) is low, the resin exhibits good flexibility, and also exhibits good tackiness. In addition, this, combined with the presence of an ether structure in the main chain, results in superior adhesion to both highly polar and less polar materials.

[0045] The alkyl group may be linear, branched, or cyclic, but is preferably linear or branched. Preferred linear alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, and n-dodecyl. Preferred branched alkyl groups include 2-ethylhexyl and 2-methylpentyl. Among these, n-octyl, n-decyl, and n-dodecyl are preferred from the viewpoint of low glass transition temperature (Tg) and tackiness, with n-octyl and n-decyl being particularly preferred, and n-octyl being even more preferred. The alkyl group may have a substituent.

[0046] Aliphatic polycarbonate resin A contains two or more types of R 1 may contain two or more types of R 2 As described above, R 1 and R 2 may be the same or different.

[0047] R in formula (Ic) and formula (Id) 3 and R 4 As described above, is a hydrocarbon group having a crosslinkable functional group. Examples of the crosslinkable functional group include a (meth)acryloyl group; alkenyl groups such as an allyl group and a vinyl group; an alkynyl group; an alkoxy group, and an oxy(meth)acryloyl group. Among these, from the viewpoint of self-crosslinking, a (meth)acryloyl group or an allyl group is preferred, and a (meth)acryloyl group is particularly preferred. In this specification, (meth)acryloyl means both acryloyl and methacryloyl. The same applies to other similar terms.

[0048] Above R 3 or R 4It is preferable that the alkyl chain has an alkyl chain, and it is particularly preferable that the alkyl chain has a linear alkyl chain. This ensures flexibility even after crosslinking, making the adhesive more suitable for use as a pressure-sensitive adhesive. From the viewpoint of such effects, the number of carbon atoms in the alkyl chain is preferably 1 to 20, more preferably 2 to 15, particularly preferably 3 to 10, and even more preferably 4 to 8. The alkyl chain may have a substituent.

[0049] Above R 3 or R 4 It is preferable that the aryl group has an ether structure, which can impart flexibility to the resulting aliphatic polycarbonate resin A.

[0050] Above R 3 or R 4 Specifically, it is preferable that the crosslinkable functional group contains a structure represented by the following formula (II) or (III): This allows the reaction of the crosslinkable functional group to proceed efficiently, regardless of the length of the alkyl group in the side chain. CH2=CH-C(=O)-OXO- (II) (In formula (II), X is an alkyl chain.) CH2=CH-CH2-YO- (III) (In formula (III), Y is a single bond or an alkyl chain.)

[0051] Also, the above R 3 or R 4 Specifically, it is particularly preferable that the structure is represented by the following formula (IV) or formula (V). CH2=CH-C(=O)-OXO-CH2- (IV) (In formula (IV), X is an alkyl chain.) CH2=CH-CH2-YO-CH2- (V) (In formula (V), Y is a single bond or an alkyl chain.)

[0052] The number of carbon atoms in the alkyl chain (X) in the above formulas (II) and (IV) is preferably 1 to 10, more preferably 2 to 8, particularly preferably 3 to 6, and even more preferably 4 to 5. The number of carbon atoms in the alkyl chain (Y) in the above formulas (III) and (V) is preferably 1 to 10, more preferably 1 to 8, particularly preferably 2 to 6, and even more preferably 2 to 4.

[0053] Aliphatic polycarbonate resin A contains two or more types of R 3 may contain two or more types of R 4 As described above, R 3 and R 4 may be the same or different.

[0054] The aliphatic polycarbonate resin A has the crosslinkable functional group (R 3 and R 4 Preferably, the aliphatic polycarbonate resin A contains 0.01 mol % or more of the crosslinkable functional group, more preferably 0.05 mol % or more, particularly preferably 0.1 mol % or more, and even more preferably 0.3 mol % or more. Furthermore, the aliphatic polycarbonate resin A preferably contains 10 mol % or less of the crosslinkable functional group, more preferably 5 mol % or less, particularly preferably 3 mol % or less, and even more preferably 1 mol % or less. By containing the crosslinkable functional group in the above amount, the aliphatic polycarbonate resin A can form a good crosslinked structure and exhibit suitable cohesive strength as a pressure-sensitive adhesive.

[0055] The aliphatic polycarbonate resin A preferably contains 0.1 mol% or more, more preferably 0.5 mol% or more, particularly preferably 0.8 mol% or more, and even more preferably 1 mol% or more, of ether structural units in the main chain (repeating units represented by formula (Ib) and repeating units represented by formula (Id)). Furthermore, the aliphatic polycarbonate resin A preferably contains 99 mol% or less, more preferably 50 mol% or less, particularly preferably 20 mol% or less, and even more preferably 10 mol% or less, of ether structural units. By including the ether structural units in the above amounts, the aliphatic polycarbonate resin A effectively lowers its glass transition temperature (Tg) and exhibits better tackiness. Note that as the content of ether structural units in the aliphatic polycarbonate resin A increases, the glass transition temperature (Tg) of the aliphatic polycarbonate resin A decreases further, and the tackiness of the adhesive tends to increase.

[0056] The number average molecular weight of the aliphatic polycarbonate resin A is preferably 15,000 or more, more preferably 20,000 or more, particularly preferably 50,000 or more, and even more preferably 80,000 or more. The number average molecular weight of the aliphatic polycarbonate resin A is preferably 2,000,000 or less, more preferably 1,000,000 or less, particularly preferably 500,000 or less, and even more preferably 300,000 or less. Having the number average molecular weight of the aliphatic polycarbonate resin A within the above range results in better tackiness and better cohesive strength after crosslinking. The number average molecular weight in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0057] The glass transition temperature (Tg) of the aliphatic polycarbonate resin A is preferably 5°C or lower, more preferably -10°C or lower, particularly preferably -20°C or lower, and even more preferably -25°C or lower. This results in excellent flexibility and better tackiness. By having the above-mentioned structure, the aliphatic polycarbonate resin A can achieve the low glass transition temperature (Tg) as described above.

[0058] The glass transition temperature (Tg) of the aliphatic polycarbonate resin A is preferably -60°C or higher, more preferably -55°C or higher, particularly preferably -45°C or higher, and even more preferably -40°C or higher. This results in good cohesive strength after crosslinking. The glass transition temperature (Tg) in this specification is measured as shown in the test examples described below.

[0059] The gel fraction of the aliphatic polycarbonate resin A is preferably 1 to 30%, particularly preferably 2 to 20%, and further preferably 4 to 10%. This makes it easier for the gel fraction after crosslinking to fall within the preferred range described below. The method for measuring the gel fraction in this specification is as shown in the test examples described below.

[0060] The 5% weight loss temperature of the aliphatic polycarbonate resin A is preferably 210 to 450°C, particularly preferably 220 to 400°C, and further preferably 230 to 350°C. This makes it easier for the 5% weight loss temperature after crosslinking to fall within the preferred range described below. The 5% weight loss temperature in this specification is measured by the method shown in the test examples described below.

[0061] The aliphatic polycarbonate resin A is preferably a polymerization reaction product of carbon dioxide and an epoxide. The aliphatic polycarbonate resin A is preferably a polymerization reaction product of carbon dioxide (CO2) and the R 1 ·R 2(hereinafter may be referred to as "epoxide E1") and R in the above-mentioned formula (Ic) and formula (Id). 3 ·R 4 and an epoxide having the formula (hereinafter sometimes referred to as "epoxide E2"), in the presence of a polymerization catalyst, while controlling the water content to a predetermined level or less as necessary (see, for example, WO 2011 / 142259). By selecting an appropriate polymerization catalyst, an ether structure can be introduced into the main chain of the aliphatic polycarbonate resin A. Since carbon dioxide can be used as a raw material for the production of the aliphatic polycarbonate resin A, the carbon dioxide can be effectively utilized.

[0062] The epoxide E1 is not particularly limited as long as it can form the repeating units represented by formula (Ia) and formula (Ib) in the above-mentioned structure SA through the above-mentioned polymerization reaction, but is preferably a compound represented by the following formula (VI) or a derivative of said compound. In this specification, the term "derivative" refers to a compound in which one or more hydrogen atoms of the original compound have been substituted with a group (substituent) other than a hydrogen atom.

[0063] [ka] (In formula (VI), p is a non-negative integer.)

[0064] In formula (VI), p is preferably 0 to 15, more preferably 2 to 13, particularly preferably 4 to 11, and further preferably 6 to 9.

[0065] Specific examples of the epoxide E1 include ethylene oxide, propylene oxide, 1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxynonane, 1,2-epoxydecane, 1,2-epoxyundecane, and 1,2-epoxydodecane. Among these, 1,2-epoxyhexane, 1,2-epoxyoctane, and 1,2-epoxydecane are preferred from the viewpoint of low glass transition temperature (Tg) and tackiness, with 1,2-epoxyoctane and 1,2-epoxydecane being particularly preferred, and 1,2-epoxydecane being even more preferred. The epoxides listed above may have a substituent.

[0066] The epoxide E2 is not particularly limited as long as it can form the repeating units represented by formula (Ic) and formula (Id) in the above-mentioned structure SA through the above-mentioned polymerization reaction. However, it is preferably a compound represented by the following formula (VII) or formula (VIII) or a derivative of said compound.

[0067] [ka]

[0068] [ka]

[0069] CL in formula (VII) and formula (VIII) is a crosslinkable functional group. The crosslinkable functional group can be R in formula (Ic) and formula (Id) described above. 3 and R 4 Among these, CL in formula (VII) is preferably a (meth)acryloyl group, and CL in formula (VIII) is preferably an allyl group.

[0070] X in formula (VII) is an alkyl chain. The number of carbon atoms in the alkyl chain is the same as the number of carbon atoms in the alkyl chain (X) in formulas (II) and (IV). Y in formula (VIII) is a single bond or an alkyl chain. The number of carbon atoms in the alkyl chain is the same as the number of carbon atoms in the alkyl chain (Y) in formulas (III) and (V).

[0071] Specific examples of the epoxide E2 include 4-hydroxyalkyl (meth)acrylate glycidyl ethers such as 4-hydroxymethyl (meth)acrylate glycidyl ether, 4-hydroxyethyl (meth)acrylate glycidyl ether, 4-hydroxypropyl (meth)acrylate glycidyl ether, 4-hydroxybutyl (meth)acrylate glycidyl ether, 4-hydroxypentyl (meth)acrylate glycidyl ether, and 4-hydroxyhexyl (meth)acrylate glycidyl ether; allyl glycidyl ether; and allyl alkyl glycidyl ethers such as allylmethyl glycidyl ether. Among these, from the viewpoint of flexibility after crosslinking and thus suitability as a pressure-sensitive adhesive, 4-hydroxybutyl (meth)acrylate glycidyl ether or allyl glycidyl ether is preferred, and 4-hydroxybutyl acrylate glycidyl ether is particularly preferred. The epoxides listed above may have a substituent.

[0072] The epoxide E1 and epoxide E2 used in the polymerization reaction step may each be one type only, or two or more types. When two or more types are used, the combination and ratio thereof may be adjusted appropriately depending on the purpose.

[0073] The molar ratio of the epoxide E1 and epoxide E2 used in the polymerization reaction step is preferably 99.99:0.01 to 90:10, more preferably 99.95:0.05 to 95:5, particularly preferably 99.9:0.1 to 99:1, and further preferably 99.7:0.3 to 99.5:0.5.

[0074] The polymerization catalyst used in producing the aliphatic polycarbonate resin A is not particularly limited as long as it can introduce an ether structure into the main chain of the aliphatic polycarbonate resin A. Specifically, a double metal cyanide complex catalyst (also known as a "DMC catalyst") is preferred. Preferred metals in the DMC catalyst include a combination of cobalt and zinc, cobalt and nickel, or zinc and nickel, with a combination of cobalt and zinc being particularly preferred. Preferred DMC catalysts include Zn(Co[CN]), Co(Ni[CN]), and Zn(Ni(CN)). Zn(Co[CN]) is particularly preferred.

[0075] As described above, the polymerization reaction of the aliphatic polycarbonate resin A is preferably carried out in a pressure vessel. By changing the amount of polymerization catalyst used in this polymerization reaction, the carbon dioxide pressure, the polymerization temperature, the polymerization time, etc., the content ratio of the ether structural unit in the aliphatic polycarbonate resin A and the molecular weight of the aliphatic polycarbonate resin A can be adjusted.

[0076] The amount of the polymerization catalyst used, for example, in the case of a DMC catalyst, is preferably 0.1 to 15 mg, particularly preferably 0.1 to 10 mg, and even more preferably 0.1 to 2 mg, per gram of epoxy monomer. If the amount of the polymerization catalyst used is reduced, the molecular weight of the aliphatic polycarbonate resin A tends to increase.

[0077] The pressure of the carbon dioxide is preferably 0.1 to 10 MPa, more preferably 0.3 to 7.5 MPa, particularly preferably 0.5 to 6 MPa, and further preferably 0.7 to 5 MPa. Increasing the carbon dioxide pressure tends to increase the content of carbonate structural units in the aliphatic polycarbonate resin A.

[0078] The amount of carbon dioxide introduced into the aliphatic polycarbonate resin A (CO2 introduction rate) is preferably 10% by mass or more, particularly preferably 15% by mass or more, and further preferably 20% by mass or more. The method for calculating this CO2 introduction rate is as shown in the test examples described later.

[0079] The polymerization temperature is preferably −15 to 95° C., particularly preferably 0 to 75° C., and further preferably 25 to 70° C. If the polymerization temperature is increased, the content ratio of the ether structural unit can be increased and the polymerization time can be shortened.

[0080] The polymerization time is preferably 1 to 48 hours, particularly preferably 2 to 30 hours, and further preferably 5 to 24 hours. If the polymerization time is extended within this range, the molecular weight of the aliphatic polycarbonate resin A tends to increase.

[0081] The polymerization method may be either solution polymerization or bulk polymerization. Examples of the solvent (polymerization solvent) used in solution polymerization include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, carbonate-based solvents such as dimethyl carbonate and ethylene carbonate, and cellosolve-based solvents such as ethyl cellosolve.

[0082] The PSA in the first embodiment contains 50% by mass or more, preferably 60% by mass or more, particularly preferably 70% by mass or more, and even more preferably 80% by mass or more of aliphatic polycarbonate resin A. There is no particular upper limit to the content, and it may be 100% by mass.

[0083] The PSA of the first embodiment may contain components other than the aliphatic polycarbonate resin A. Examples of such components include various additives known in the field of PSA, such as tackifiers, UV absorbers, dyes, pigments, antioxidants, antidegradants, antistatic agents, flame retardants, light stabilizers, softeners, silane coupling agents, and fillers.

[0084] (2) Pressure-sensitive adhesive in the second embodiment The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet according to the second embodiment contains 50% by mass or more of aliphatic polycarbonate resin crosslinked product B. The aliphatic polycarbonate resin crosslinked product B is a crosslinked product of an aliphatic polycarbonate resin A having an ether structure in the main chain and a crosslinkable functional group in the side chain, preferably a crosslinked product of an aliphatic polycarbonate resin A having the aforementioned Structure SA, and particularly preferably a self-crosslinked product of an aliphatic polycarbonate resin A having the aforementioned Structure SA.

[0085] Crosslinked aliphatic polycarbonate resin B, which is a crosslinked product of aliphatic polycarbonate resin A having structure SA, maintains a low glass transition temperature (Tg) like aliphatic polycarbonate resin A having structure SA and exhibits flexibility and tackiness, while its crosslinked structure increases cohesive strength, resulting in better adhesive strength and holding power.

[0086] The crosslinked aliphatic polycarbonate resin B may be a crosslinked product obtained by crosslinking an aliphatic polycarbonate resin A using a desired crosslinking agent, but is preferably a crosslinked product obtained by self-crosslinking an aliphatic polycarbonate resin A, and particularly preferably a crosslinked product obtained by self-crosslinking an aliphatic polycarbonate resin A having a structure SA. Specifically, the crosslinked aliphatic polycarbonate resin B may be a crosslinked product obtained by self-crosslinking an aliphatic polycarbonate resin A having a crosslinkable functional group (R in formula (Ic) and formula (Id)) in the side chain of the aliphatic polycarbonate resin A. 3 and R 4 Preferably, the aliphatic polycarbonate resin A is one in which a plurality of aliphatic polycarbonate resins A are crosslinked via the crosslinkable functional groups (crosslinkable functional groups possessed by the aliphatic polycarbonate resin A).

[0087] The crosslinked aliphatic polycarbonate resin B can be preferably produced by irradiating an aliphatic polycarbonate resin A with active energy rays. The irradiation with active energy rays causes crosslinkable functional groups in the side chains of the aliphatic polycarbonate resin A to react with each other, forming a crosslinked structure.

[0088] Here, the active energy ray refers to an electromagnetic wave or a charged particle beam that has an energy quantum, and specific examples thereof include ultraviolet rays, electron beams, etc. Among active energy rays, ultraviolet rays are particularly preferred because they are easy to handle.

[0089] Ultraviolet light irradiation can be performed using a high-pressure mercury lamp, an electrodeless lamp, an LED lamp, a xenon lamp, etc., and the amount of ultraviolet light irradiation is set to an illuminance of 50 to 1000 mW / cm. 2 The light intensity is preferably about 50 to 10,000 mJ / cm. 2 is preferably 80 to 5000 mJ / cm 2 More preferably, it is 200 to 2000 mJ / cm 2 On the other hand, the electron beam irradiation can be carried out by an electron beam accelerator or the like, and the irradiation dose of the electron beam is preferably about 10 to 1000 krad.

[0090] When ultraviolet rays are used as the active energy rays for crosslinking the aliphatic polycarbonate resin A, it is preferable to add a photopolymerization initiator to the aliphatic polycarbonate resin A. By adding a photopolymerization initiator in this way, the aliphatic polycarbonate resin A can be efficiently crosslinked, and the crosslinking time and the exposure dose of the active energy rays can be reduced.

[0091] Examples of such photopolymerization initiators include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthracene, benzoin, benzoin methyl ether ... Examples of suitable thioxanthraquinones include thraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, and lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate. These may be used alone or in combination of two or more.

[0092] The amount of the photopolymerization initiator is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, particularly preferably 1 part by mass or more, and even more preferably 1.3 parts by mass or more, relative to 100 parts by mass of the aliphatic polycarbonate resin A. The amount of the photopolymerization initiator is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, particularly preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less.

[0093] The gel fraction of the aliphatic polycarbonate resin crosslinked product B is preferably 15% or more, more preferably 20% or more, particularly preferably 30% or more, and even more preferably 40% or more. This allows the adhesive to exhibit excellent cohesive strength. Furthermore, the gel fraction is preferably 85% or less, more preferably 80% or less, particularly preferably 75% or less, and even more preferably 70% or less. This ensures flexibility and maintains good adhesive strength.

[0094] The glass transition temperature (Tg) of the crosslinked aliphatic polycarbonate resin B is preferably 5°C or lower, more preferably -10°C or lower, particularly preferably -20°C or lower, and even more preferably -30°C or lower. This results in excellent flexibility and better tackiness. The crosslinked aliphatic polycarbonate resin B has a structure obtained by crosslinking the aliphatic polycarbonate resin A having the above-mentioned structure SA, and thus can achieve the above-mentioned low glass transition temperature (Tg).

[0095] The glass transition temperature (Tg) of the crosslinked aliphatic polycarbonate resin B is preferably −60° C. or higher, more preferably −55° C. or higher, particularly preferably −50° C. or higher, and even more preferably −45° C. or higher, which results in better cohesive strength.

[0096] The 5% weight loss temperature of the aliphatic polycarbonate resin crosslinked product B is preferably 200°C or higher, more preferably 210°C or higher, particularly preferably 220°C or higher, and even more preferably 230°C or higher. This gives the aliphatic polycarbonate resin crosslinked product B excellent heat resistance and makes it suitable as an adhesive to be used at high temperatures. There are no particular restrictions on the upper limit of the 5% weight loss temperature of the aliphatic polycarbonate resin crosslinked product B, but it is usually preferably 450°C or lower, more preferably 400°C or lower, particularly preferably 350°C or lower, and even more preferably 300°C or lower.

[0097] The PSA in the second embodiment contains 50% by mass or more, preferably 60% by mass or more, particularly preferably 70% by mass or more, and even more preferably 80% by mass or more of aliphatic polycarbonate resin B. The upper limit of the content is not particularly limited, and may be 100% by mass.

[0098] The pressure-sensitive adhesive in the second embodiment may contain components other than the aliphatic polycarbonate resin B. Examples of such components include a photopolymerization initiator or its decomposition product, as well as various additives known in the pressure-sensitive adhesive field, such as a tackifier, an ultraviolet absorber, a dye, a pigment, an antioxidant, an antidegradant, an antistatic agent, a flame retardant, a light stabilizer, a softener, a silane coupling agent, and a filler.

[0099] 2. Adhesive layer The thickness of the adhesive layer in the adhesive sheets according to the first and second embodiments (measured in accordance with JIS K7130) is preferably 1 μm or more as a lower limit, more preferably 5 μm or more, particularly preferably 10 μm or more, and even more preferably 20 μm or more, from the viewpoint of adhesive strength and holding power.

[0100] Furthermore, from the viewpoint of coating properties, handling properties, etc., the thickness of the pressure-sensitive adhesive layer is preferably 80 μm or less as an upper limit, more preferably 50 μm or less, particularly preferably 40 μm or less, and even more preferably 30 μm or less.

[0101] 3.Configuration example Specific configurations of examples of the pressure-sensitive adhesive sheets according to the first and second embodiments are shown in FIGS. 1 and 2. FIG.

[0102] As shown in Figure 1, an adhesive sheet 1A according to one embodiment is composed of, from the bottom up, a release sheet 12, an adhesive layer 11 laminated on the release surface of the release sheet 12, and a substrate 13 laminated on the adhesive layer 11.

[0103] 2, a pressure-sensitive adhesive sheet 1B according to another embodiment is composed of two release sheets 12a and 12b and a pressure-sensitive adhesive layer 11 sandwiched between the two release sheets 12a and 12b so as to be in contact with the release surfaces of the two release sheets 12a and 12b. In this specification, the release surface of a release sheet refers to the surface of the release sheet that has releasability, and includes both a surface that has been subjected to a release treatment and a surface that exhibits releasability even without being subjected to a release treatment.

[0104] 3-1.Each element (1) Adhesive layer The adhesive layer 11 in this embodiment is as described above, and is made of an adhesive containing 50% by mass or more of an aliphatic polycarbonate resin A, or an adhesive containing 50% by mass or more of aliphatic polycarbonate resin crosslinked body B.

[0105] (2) Release sheet The release sheets 12, 12a, 12b protect the adhesive layer 11 until the adhesive sheet 1 is used, and are peeled off when the adhesive sheets 1A, 1B (adhesive layer 11) are to be used. In the adhesive sheets 1A, 1B according to this embodiment, one or both of the release sheets 12, 12a, 12b are not necessarily required.

[0106] Examples of the release sheets 12, 12a, and 12b include plastic films such as polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, and fluororesin film, and crosslinked films thereof; and paper such as fine paper, glassine paper, kraft paper, and clay-coated paper. Furthermore, laminates of these may also be used.

[0107] The release surfaces of the release sheets 12, 12a, and 12b (particularly the surfaces that come into contact with the pressure-sensitive adhesive layer 11) are preferably subjected to a release treatment. Examples of release agents used for the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. One of the release sheets 12a and 12b may be a heavy-release type release sheet with a high release strength, and the other may be a light-release type release sheet with a low release strength.

[0108] There are no particular restrictions on the thickness of the release sheets 12, 12a, 12b, but it is usually about 20 to 150 μm.

[0109] (3) Base material The substrate 13 is not particularly limited, and any substrate sheet commonly used in conventional pressure-sensitive adhesive sheets can be used. Examples include, in addition to the desired optical components, woven or nonwoven fabrics made from fibers such as polyester, acrylic, or rayon; synthetic paper; fine paper, glassine paper, impregnated paper, coated paper, and other papers; metal foils such as aluminum and copper; foams such as urethane foam and polyethylene foam; polyester films such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene succinate, and polybutylene adipate terephthalate (compound); polyurethane films, polyethylene films, polypropylene films, cellulose films such as triacetyl cellulose; plastic films such as polyvinyl chloride films, polyvinylidene chloride films, polyvinyl alcohol films, ethylene-vinyl acetate copolymer films, polystyrene films, polycarbonate films, acrylic resin films, norbornene resin films, and cycloolefin resin films; and laminates of two or more of these. The plastic films may be uniaxially or biaxially stretched.

[0110] The thickness of the substrate 13 varies depending on the type, but is usually 10 to 150 μm, preferably 20 to 100 μm, and particularly preferably 25 to 75 μm.

[0111] 3-2. Manufacturing method To manufacture the adhesive sheet 1A according to the first embodiment, it is preferable to apply an adhesive solution (coating solution) containing aliphatic polycarbonate resin A to the release surface of the release sheet 12, perform a heat treatment to form an adhesive layer 11, and then laminate a substrate 13 onto the adhesive layer 11.

[0112] Furthermore, to manufacture the adhesive sheet 1B according to the first embodiment, it is preferable to apply a solution (coating solution) of an adhesive containing aliphatic polycarbonate resin A to the release surface of one of the release sheets 12a (or 12b), perform a heat treatment to form an adhesive layer 11, and then overlap the release surface of the other release sheet 12b (or 12a) on the adhesive layer 11.

[0113] On the other hand, to produce the pressure-sensitive adhesive sheet 1A according to the second embodiment, it is preferable to apply a solution (coating solution) of a pressure-sensitive adhesive containing aliphatic polycarbonate resin A to the release surface of release sheet 12, perform a heat treatment, laminate substrate 13 on the coating layer, and finally irradiate the coating layer with active energy rays to crosslink the coating layer to form pressure-sensitive adhesive layer 11. Irradiation of active energy rays can be carried out, for example, through release sheet 12.

[0114] Furthermore, to manufacture the pressure-sensitive adhesive sheet 1B according to the second embodiment, it is preferable to apply a solution (coating solution) of a pressure-sensitive adhesive containing aliphatic polycarbonate resin A to the release surface of one release sheet 12a (or 12b), heat-treat it, and then overlap the release surface of the other release sheet 12b (or 12a) on the coating layer, and finally irradiate the coating layer with active energy rays to crosslink the coating layer to form the pressure-sensitive adhesive layer 11. Irradiation of active energy rays can be carried out through the desired release sheet (12a or 12b).

[0115] Examples of dilution solvents that can be used to dilute the pressure-sensitive adhesive to form a coating solution include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve-based solvents such as ethyl cellosolve.

[0116] The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within the range that allows coating, and can be selected appropriately depending on the situation. For example, the adhesive is diluted to a concentration of 10 to 40 mass %. Note that the addition of a dilution solvent is not a necessary condition for obtaining the coating solution, and as long as the adhesive has a viscosity that allows coating, it is not necessary to add a dilution solvent. In this case, the adhesive itself becomes the coating solution.

[0117] The coating solution can be applied by, for example, bar coating, knife coating, comma coating, roll coating, blade coating, die coating, gravure coating, or the like.

[0118] The coating film of the coating solution is subjected to a heat treatment to volatilize the dilution solvent and form a pressure-sensitive adhesive layer (or coating layer). The heating conditions are, for example, preferably 30 to 120°C for 1 to 10 minutes, and particularly preferably 100 to 120°C for 1 to 5 minutes.

[0119] 4. Uses of adhesive sheets The pressure-sensitive adhesive sheets according to the first and second embodiments can be used for, for example, attaching labels to various containers, daily necessities, electrical and electronic devices, various machines, medical instruments, etc., and for bonding members together.

[0120] The material of the adherend is not particularly limited, and may be, for example, any of metals such as stainless steel, aluminum, copper, etc.; glass; highly polar materials such as resins such as polycarbonate resin, acrylic resin, polyethylene terephthalate resin, etc.; and low polar materials such as polyolefin resins such as polyethylene and polypropylene, polyacetal, polytetrafluoroethylene, etc.

[0121] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0122] For example, release sheet 12 of pressure-sensitive adhesive sheet 1A may be omitted, or either release sheet 12a or 12b of pressure-sensitive adhesive sheet 1B may be omitted. [Example]

[0123] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0124] Example 1 (1) Synthesis of polymerization catalyst 1.33 g of potassium hexacyanocobaltate(III) (K3[Co(CN)6]; Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 20 mL of deionized water and added dropwise over 45 min to a vigorously stirred zinc chloride solution (11.42 g of ZnCl2 dissolved in a mixture of 60 mL of deionized water and 30 mL of t-butyl alcohol) at 50 °C. The mixture was then vigorously stirred for 60 min. The resulting white suspension was centrifuged at 5000 rpm to isolate a white solid. The isolated white solid was resuspended in a solution of t-butyl alcohol and deionized water (volume ratio: t-butyl alcohol:deionized water = 5:5) with vigorous stirring for 30 min. The centrifugation and resuspension were then repeated several times while gradually increasing the amount of t-butyl alcohol to water (volume ratio: t-butyl alcohol:deionized water was changed from 6:4 to 7:3, 8:2, and 9:1). Finally, the white solid was resuspended in t-butyl alcohol and isolated by centrifugation, and then dried under vacuum at 50 °C to a predetermined mass to obtain the DMC catalyst Zn3(C0[CN]6)2.

[0125] (2) Polymer synthesis As raw material monomers, 1,2-epoxydecane (Edec; 1,2-decylene oxide) as epoxide E1 and 4-hydroxybutyl acrylate glycidyl ether (4HBAGE; manufactured by Mitsubishi Chemical Corporation) as epoxide E2 were prepared. 1,2-Epoxydecane and 4-hydroxybutyl acrylate glycidyl ether were mixed in a molar ratio of 99:1 and diluted with 50 parts by mass of toluene (dehydrated toluene manufactured by Kanto Chemical Co., Inc., purity of 99.5% or higher confirmed by GC) as the polymerization solvent.

[0126] The raw material monomers (total, excluding the solvent) were added to a pressure vessel in a ratio of 1 mg of the DMC catalyst obtained in (1) above to 1 g of the raw material monomers. Furthermore, phenothiazine (manufactured by Tokyo Chemical Industry Co., Ltd., purity of 99.5% or higher as confirmed by GC) was added as a polymerization inhibitor to a concentration of 200 ppm. The mixture was then stirred under an argon atmosphere.

[0127] Next, the pressure vessel was purged with CO2, and then CO2 was introduced into the pressure vessel using a liquid pump to set the pressure inside the pressure vessel to 4 MPa. Then, the mixture was stirred at 60°C for 18 hours to carry out a polymerization reaction.

[0128] After the reaction was completed, toluene was added to the contents of the pressure vessel to form a solution, and the solution was dropped into methanol containing 1M hydrochloric acid to carry out reprecipitation purification. The resulting precipitate was collected using filter paper and dissolved in chloroform, after which impurities were removed using a membrane filter (manufactured by Advantec Toyo Co., Ltd., pore size 3.00 μm). The solution was then poured into a Teflon (registered trademark) dish and dried in a drying oven at 50°C for 20 hours to obtain a polymer.

[0129] The structure of the obtained polymer (aliphatic polycarbonate resin) is 1 The 1H-NMR (apparatus: Biospin Avance 500, manufactured by Bruker) was used to confirm the properties. The chart obtained is shown in Figure 1. In addition, in the obtained aliphatic polycarbonate resin, the R 1 and R 2is -CH 17 and R 3 and R 4 was -CO-(CH2)4-OC(=O)-CH=CH2.

[0130] Based on the above results, the ratio of ether structural units to carbonate units was estimated from the integral ratio of the corresponding methylene hydrogens. As a result, the ratio (content) of ether structural units in the obtained aliphatic polycarbonate resin was 1.6%, and the ratio (content) of carbonate was 98.4%. The ratio of ether structural units was calculated using the following formula based on α, β, and γ in the chart. Ether structural unit ratio [%] = {γ / (α+β+γ)} × 100

[0131] The aliphatic polycarbonate resin obtained above was dissolved in ethyl acetate, and 1.5 parts by mass of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator was added to 100 parts by mass of the aliphatic polycarbonate resin (solid content equivalent; the same applies below), and the mixture was thoroughly stirred to prepare a pressure-sensitive adhesive coating solution.

[0132] The adhesive coating solution was applied using a coater to the release-treated surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET381031"), one side of which had been treated with a silicone-based release agent. The coating layer was then heated at 100°C for 1 minute to form an adhesive layer with a thickness of 25 μm. The adhesive layer on the release sheet was then bonded to a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4360", thickness 50 μm) as a substrate, and this was used as an adhesive sheet (pre-UV; corresponding to the adhesive sheet according to the first embodiment).

[0133] The thickness of the pressure-sensitive adhesive layer is a value measured in accordance with JIS K7130 using a constant pressure thickness measuring instrument (manufactured by Teclock Corporation, product name "PG-02").

[0134] Next, the pressure-sensitive adhesive sheet was irradiated with active energy rays through the release sheet under the conditions described below to crosslink the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer after crosslinking was made of a crosslinked aliphatic polycarbonate resin. The pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer after crosslinking is referred to as a pressure-sensitive adhesive sheet (post-UV; corresponding to the pressure-sensitive adhesive sheet according to the second embodiment).

[0135] <Activated energy ray irradiation conditions> -High pressure mercury lamp used ·Illuminance 200mW / cm 2 , light intensity 1800mJ / cm 2 The UV illuminance and light intensity meter used is the "UVPF-A1" manufactured by Eye Graphics Co., Ltd.

[0136] Examples 2 to 4 Polymers and adhesive sheets were produced in the same manner as in Example 1, except that the blending ratio (molar ratio) of 1,2-epoxydecane to 4-hydroxybutyl acrylate glycidyl ether was changed to 99.5:0.5 (Example 2), 99.7:0.3 (Example 3), and 99.9:0.1 (Example 4).

[0137] The structure of the obtained polymer (aliphatic polycarbonate resin) is 1 The results were confirmed by H-NMR (apparatus: manufactured by Bruker, product name "Biospin Avance 500"). The ratio of ether structural units and the carbonate ratio in the aliphatic polycarbonate resin are shown in Table 1.

[0138] [Examples 5 and 6] As raw material monomers, 1,2-epoxyoctane (Eoct; 1,2-octylene oxide) as epoxide E1 and 4-hydroxybutyl acrylate glycidyl ether (4HBAGE; manufactured by Mitsubishi Chemical Corporation) as epoxide E2 were prepared. 1,2-Epoxyoctane and 4-hydroxybutyl acrylate glycidyl ether were mixed in a molar ratio of 99.9:0.1 (Example 5) and 99.7:0.3 (Example 6).

[0139] A polymer and a pressure-sensitive adhesive sheet were produced in the same manner as in Example 1, except that the raw material monomers were used and bulk polymerization was carried out without using a polymerization solvent. The structure of the resulting polymer (aliphatic polycarbonate resin) was as follows: 1 The results were confirmed by H-NMR (apparatus: manufactured by Bruker, product name "Biospin Avance 500"). The ratio of ether structural units and the carbonate ratio in the aliphatic polycarbonate resin are shown in Table 1.

[0140] Example 7 As raw material monomers, 1,2-epoxyoctane (Eoct; 1,2-octylene oxide) as epoxide E1 and allyl glycidyl ether (AGE) as epoxide E2 were prepared. 1,2-Epoxyoctane and allyl glycidyl ether were mixed in a molar ratio of 90:10.

[0141] A polymer and a pressure-sensitive adhesive sheet were produced in the same manner as in Example 1, except that the raw material monomers were used and bulk polymerization was carried out without using a polymerization solvent. The structure of the resulting polymer (aliphatic polycarbonate resin) was as follows: 1 The results were confirmed by H-NMR (apparatus: manufactured by Bruker, product name "Biospin Avance 500"). The ratio of ether structural units and the carbonate ratio in the aliphatic polycarbonate resin are shown in Table 1.

[0142] Comparative Example 1 (1) Synthesis of polymerization catalyst (R,R)-N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexanecobalt(II) (Sigma-Aldrich Japan, LLC, product name "(R,R)-salcyCoII") and pentafluorobenzoic acid (Tokyo Chemical Industry Co., Ltd.) were weighed out in a molar ratio of 1:1.1 and placed in a flask, followed by the addition of dehydrated toluene. The flask was shielded from light with aluminum foil and the reaction was carried out at room temperature for 20 hours. After the reaction was complete, the solvent was removed under reduced pressure and the mixture was washed several times with excess hexane. The mixture was then vacuum dried at room temperature to obtain a cobalt salen complex.

[0143] (2) Polymer synthesis The epoxy monomer, 1,2-epoxypropane (propylene oxide; PO), the cobalt salen complex obtained in (1) above as the polymerization catalyst, and bis(triphenylphosphoranylidene)ammonium chloride (PPNCl) as the cocatalyst were weighed out in a molar ratio of epoxy monomer:polymerization catalyst:cocatalyst = 2000:1:1 and stirred in a pressure vessel. All of these operations were carried out with an argon atmosphere inside the pressure vessel. Note that this polymerization process was bulk polymerization without the use of a polymerization solvent.

[0144] Next, the inside of the pressure vessel was purged with CO2, and then CO2 was introduced into the pressure vessel using a liquid pump to set the pressure inside the pressure vessel to 1.5 MPa. Then, the mixture was stirred at 23°C for 5 hours to carry out the polymerization reaction.

[0145] After the reaction was completed, chloroform was added to the contents of the pressure vessel to prepare a chloroform solution, which was then concentrated using a rotary evaporator. The concentrated solution was added dropwise to stirred methanol containing 1M hydrochloric acid to precipitate the product. The product was then recovered by vacuum filtration using a diaphragm pump. The recovered product was dissolved again in chloroform, and impurities were removed using a membrane filter (manufactured by Advantec Toyo Co., Ltd., pore size 3.00 μm). The solution was then poured into a Teflon (registered trademark) dish and dried in a drying oven at 50°C for 20 hours to obtain a polymer. The structure of this polymer (aliphatic polycarbonate resin; side chain carbon number 1) was as follows: 1 The analysis was performed using H-NMR (apparatus: manufactured by Bruker, product name "Biospin Avance 500"). The resulting chart is shown in Figure 4.

[0146] Based on the above results, the ratio of carbonate units to ether structural units was estimated from the integral ratio of the corresponding methylene hydrogens. As a result, no γ peak was observed, and therefore the ratio (content; mass basis) of ether structural units in the obtained aliphatic polycarbonate resin was 0.0%.

[0147] (3) Manufacturing of adhesive sheets The aliphatic polycarbonate resin obtained above was used to produce a pressure-sensitive adhesive sheet in the same manner as in Example 1. The pressure-sensitive adhesive sheet obtained had no tackiness in the pressure-sensitive adhesive layer, and the adhesive strength and holding power could not be measured.

[0148] Comparative Example 2 As raw material monomers, 1,2-epoxypropane (propylene oxide; PO) and 4-hydroxybutyl acrylate glycidyl ether (4HBAGE; manufactured by Mitsubishi Chemical Corporation) were prepared as epoxide E2. 1,2-Epoxypropane and 4-hydroxybutyl acrylate glycidyl ether were mixed in a mass ratio of 90:10.

[0149] The same polymer preparation procedure as in Example 1 was carried out, except that the raw material monomers were used and bulk polymerization was carried out without using a polymerization solvent. However, gelation occurred, and it was not possible to obtain a polymer whose physical properties could be measured.

[0150] [Test Example 1] <Measurement of number average molecular weight (Mn)> The number average molecular weights (Mn) of the aliphatic polycarbonate resins prepared in the Examples and Comparative Examples were measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement) and converted into standard polystyrene. The results are shown in Table 1. [Measurement conditions] GPC measuring device: Tosoh Corporation, HLC-8320 GPC columns (passed in the following order): Tosoh Corporation TSK guard column SuperH-H TSK gel SuperHM-H TSK gel SuperHM-H TSK gel SuperH2000 Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0151] [Test Example 2] <Measurement of glass transition temperature (Tg)> The aliphatic polycarbonate resins (before UV irradiation) prepared in the Examples and Comparative Examples, and the aliphatic polycarbonate crosslinked bodies (after UV irradiation) constituting the adhesive layers of the PSA sheets (after UV irradiation) produced in the Examples, were measured using a differential scanning calorimeter (TA Instruments Japan, product name "DSC Q2000") to determine their glass transition temperatures (Tg). Specifically, 4 mg of the polymer sample was taken, placed in an aluminum pan, and sealed with a lid. The sample was heated and cooled in a dry nitrogen atmosphere from -70°C to 70°C at a temperature increase and decrease rate of 10°C / min. A DSC curve was created using the data from the second heating stage. The glass transition temperature (Tg) was determined as the temperature at the intersection of a straight line extending the low-temperature baseline of the DSC curve toward the high-temperature side and a tangent drawn at the point where the gradient of the step-like change in the glass transition curve was maximum. The results are shown in Table 1.

[0152] [Test Example 3] <Measurement of gel fraction> The pressure-sensitive adhesive sheets (before UV) and pressure-sensitive adhesive sheets (after UV) produced in the examples and comparative examples were cut to a size of 80 mm x 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200), and the mass was weighed on a precision balance. The mass of the mesh alone was subtracted to calculate the mass of the pressure-sensitive adhesive alone. This mass was designated M1.

[0153] Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 72 hours. The adhesive was then removed and air-dried for 24 hours in an environment with a temperature of 23°C and a relative humidity of 50%, and then dried in an oven at 80°C for 12 hours. After drying, the mass was weighed using a precision balance, and the mass of the mesh alone was subtracted to calculate the mass of the adhesive alone. This mass was designated M2. The gel fraction (%) was calculated as (M2 / M1) × 100. This was used to calculate the gel fraction (%) of each adhesive (aliphatic polycarbonate resin (before UV irradiation) and aliphatic polycarbonate resin crosslinked body (after UV irradiation)). The results are shown in Table 1.

[0154] [Test Example 4] <Measurement of 5% weight loss temperature> The aliphatic polycarbonate resins (before UV irradiation) prepared in the Examples and Comparative Examples, as well as the crosslinked aliphatic polycarbonate resins (after UV irradiation) constituting the pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets (after UV irradiation) produced in the Examples, were subjected to thermogravimetry using a simultaneous differential thermal and thermogravimetry analyzer (Shimadzu Corporation, product name "DTG-60") with nitrogen as the inlet gas, at a gas inflow rate of 100 ml / min and a heating rate of 20°C / min, while the temperature was raised from 40°C to 550°C (in accordance with JIS K7120 "Methods for Thermogravimetric Measurement of Plastics"). Based on the obtained thermogravimetric curves, the temperature at which the mass would decrease by 5% relative to the mass at 100°C (5% weight loss temperature) was determined. The results are shown in Table 1.

[0155] [Test Example 5] <Measurement of adhesive strength> The pressure-sensitive adhesive sheets (before UV irradiation) and pressure-sensitive adhesive sheets (after UV irradiation) produced in the Examples and Comparative Examples were cut into 25 mm widths and 300 mm lengths. The release sheets were peeled from the pressure-sensitive adhesive sheets in an environment of 23°C and 50% RH, and the exposed pressure-sensitive adhesive layers were attached to the three types of adherends listed below. For attachment, a 2 kg roller was moved back and forth once to press the pressure-sensitive adhesive sheet onto the adherend. The sheets were then left for 24 hours in an environment of 23°C and 50% RH, and used as samples for adhesive strength measurements.

[0156] Next, under conditions of 23°C and 50% RH, a tensile tester (manufactured by Orientec Co., Ltd., product name "Tensilon") was used to measure the adhesive strength (N / 25 mm) when the laminate of the base film and adhesive layer in the adhesive strength measurement sample was peeled from the adherend at a peel speed of 300 mm / min and a peel angle of 180°. Measurements were conducted under conditions other than those described here in accordance with JIS Z0237:2000. The results are shown in Table 1. Note that for the polypropylene (PP) plate adherend of the adhesive sheet of Example 1 (before UV treatment), zipping occurred, resulting in a range of adhesive strength. Therefore, the adhesive strength value was read as the average of the maximum and minimum values.

[0157] <Adherend> · Stainless steel (SUS) plate (SUS304, 360 - finish) · Polycarbonate (PC) plate (manufactured by Yūkō Shōkai Co., Ltd., product name "PC (PC - 1600)", thickness: 2 mm) · Polypropylene (PP) plate (manufactured by Yūkō Shōkai Co., Ltd., product name "PP (PP - N - BN)", thickness: 2 mm)

[0158] In addition, "G", "Cf", and "Zip" in the "Adhesive strength" column of Table 1 have the following meanings respectively. G: A thin trace remained on the surface of the adherend. Cf: Cohesive failure of the adhesive layer was observed. Zip: Zipping occurred.

[0159] 〔Test Example 6〕<Measurement of holding power> The adhesive layers of the adhesive sheets (before UV) and adhesive sheets (after UV) manufactured in the examples and comparative examples were attached to a stainless steel (SUS) plate (SUS304, 360 - finish) as the adherend. At this time, the attachment area of the adhesive layer to the stainless steel plate was made to be 25 mm × 25 mm. In this way, after the stainless steel plate with the adhesive sheet attached was left standing for 15 minutes in an environment of 23°C and 50% RH, it was set in a creep tester and left standing for another 15 minutes in this state. Then, a load of 9.8 N was applied to the adhesive sheet in an environment of 40°C, and according to the measurement method of the holding power in JIS Z0237:2009, the time (maximum 70000 seconds) until the adhesive sheet fell was measured, and it was taken as the holding power (seconds) of the adhesive layer. The results are shown in Table Ⅰ.

[0160] In addition, "N.C." and "Cf" in the "Holding power" column of Table 1 have the following meanings respectively. N.C.: Not only did the adhesive sheet not fall even after exceeding 70000 seconds during the measurement of the holding power, but also there was no displacement at the attachment position of the adhesive sheet to the adherend. Cf: Cohesive failure of the adhesive layer was observed.

[0161] 〔Test Example 7〕<Calculation of CO₂ introduction rate> The CO2 incorporation rate (mass%) in the aliphatic polycarbonate resins (polymers) prepared in the Examples and Comparative Examples was calculated using the following formula. The higher the CO2 incorporation rate, the more effectively carbon dioxide is utilized. The results are shown in Table 1. CO2 introduction rate [mass%] = (amount of CO2 in polymer [g] / amount of polymer [g]) × 100 Amount of CO2 in polymer [g] = 44 × (carbonate ratio [%]) Amount of polymer [g] = {(unit molecular weight of carbonate moiety in polymer) × (carbonate ratio [%])} + {(unit molecular weight of ether moiety in polymer) × (ether structural unit ratio [%])} Carbonate ratio [%] = 100 - ether structural unit ratio [%]

[0162] [Table 1]

[0163] As can be seen from Table 1, the adhesive sheets (before UV) and adhesive sheets (after UV) of the examples were made using carbon dioxide as a manufacturing raw material, and exhibited good adhesive strength against both highly polar and less polar materials, and also had excellent holding power. [Industrial Applicability]

[0164] The pressure-sensitive adhesive sheet according to the present invention can be suitably used in both cases where the adherend is a highly polar material and where the adherend is a low polar material. [Explanation of symbols]

[0165] 1A, 1B...Adhesive sheet 11...Adhesive layer 12, 12a, 12b...Release sheet 13...Base material

Claims

1. The adhesive layer is made of an adhesive containing 50% by mass or more of an aliphatic polycarbonate resin having an ether structure in the main chain and a crosslinkable functional group in the side chain, the crosslinkable functional group is a (meth)acryloyl group or an allyl group, the aliphatic polycarbonate resin has an ether structure in its main chain and a structure in which a repeating unit represented by the following formula (Ia), a repeating unit represented by the following formula (Ib), a repeating unit represented by the following formula (Ic), and a repeating unit represented by the following formula (Id) are randomly copolymerized, the aliphatic polycarbonate resin contains the crosslinkable functional group in an amount of 0.01 mol % or more and 10 mol % or less, Adhesion strength to polypropylene is 1.5N / 25mm or more A pressure-sensitive adhesive sheet characterized by: 【Chemical 1】 (In formula (Ia) and formula (Ib), R １ and R ２ are alkyl groups having 6 or more carbon atoms, and may be the same or different. ３ and R ４ are hydrocarbon groups having the crosslinkable functional group, and may be the same or different.

2. The adhesive layer is made of an adhesive containing 50% by mass or more of a crosslinked aliphatic polycarbonate resin, which is a crosslinked aliphatic polycarbonate resin having an ether structure in the main chain and a crosslinkable functional group in the side chain, the crosslinkable functional group is a (meth)acryloyl group or an allyl group, the aliphatic polycarbonate resin has an ether structure in its main chain and a structure in which a repeating unit represented by the following formula (Ia), a repeating unit represented by the following formula (Ib), a repeating unit represented by the following formula (Ic), and a repeating unit represented by the following formula (Id) are randomly copolymerized, the aliphatic polycarbonate resin contains the crosslinkable functional group in an amount of 0.01 mol % or more and 10 mol % or less, Adhesion strength to polypropylene is 1.5N / 25mm or more A pressure-sensitive adhesive sheet characterized by: 【Chemistry 2】 (In formula (Ia) and formula (Ib), R １ and R ２ are alkyl groups having 6 or more carbon atoms, and may be the same or different. ３ and R ４ are hydrocarbon groups having the crosslinkable functional group, and may be the same or different.

3. The adhesive sheet according to claim 2, characterized in that the holding strength in accordance with JIS Z0237:2009 is such that the time until the adhesive sheet falls is 8,000 seconds or more when the adherend is stainless steel, the adhesion area is 25 mm x 25 mm, the test temperature is 40°C, and a load of 9.8 N is applied.

4. The R ３ Or the R ４ The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the alkyl group has an alkyl chain.

5. The R ３ Or the R ４ The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the copolymer has an ether structure.

6. The R ３ Or the R ４ The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the structure is represented by the following general formula (II): CH ２ =CH-C(=O)-O-X-O- ・・・(II) (In formula (II), X is an alkyl chain.)

7. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the aliphatic polycarbonate resin contains 0.1% by mass or more and 99% by mass or less of the ether structure unit in the main chain.

8. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the aliphatic polycarbonate resin has a glass transition temperature (Tg) of 5[deg.] C. or lower.

9. 3. The pressure-sensitive adhesive sheet according to claim 2, wherein the 5% weight loss temperature of the crosslinked aliphatic polycarbonate resin is 200°C or higher and 450°C or lower.

10. 3. The pressure-sensitive adhesive sheet according to claim 2, wherein the crosslinked aliphatic polycarbonate resin has a gel fraction of 15% or more and 85% or less.

11. A method for producing the pressure-sensitive adhesive sheet according to claim 1 or 2, comprising: a step of producing the aliphatic polycarbonate resin by polymerizing carbon dioxide and an epoxide. A method for producing a pressure-sensitive adhesive sheet, comprising:

Images