Cover film

Abstract

The present invention addresses the problem of providing a cover film having excellent adhesion to a glass substrate after long-term storage of a sealed body obtained by bonding the cover film to the glass substrate using a sealing solvent. The cover film according to the present invention has a support and a polymer layer containing a polymer, and is characterized in that the polar component ([delta] P) of the Hansen solubility parameter of the polymer layer is 0.0-5.1 MPa1 / 2, the dissolution rate of the polymer layer in xylene is 0.01-0.25 g * m <-2 > * s <-1 >, and the average particle size of the polymer layer is 0.1-0.5 nm. A xylene solution having a solid content concentration of 20 mass% obtained by dissolving the polymer layer in xylene has a viscosity of 17-200 cP at 25 DEG C, and the polymer layer has an elongation at break of 10% or more.

Description

Technical Field

[0001] The present invention relates to a covering film. Background Art

[0002] A known method involves using an automatic sealing device to automatically overlap a cover film having a polymer layer pre-formed on a support with a substrate (such as a slide glass) to which a few drops of a solvent (also referred to as a "sealing solvent," e.g., xylene) have been added that swells and / or dissolves the polymer layer. The substrate, which is then loaded with a subject, is then bonded to the cover film (hereinafter referred to as "sealing"). This method, for example, enables the production of specimens for microscopic observation in which the subject is fixed between the substrate and the cover film.

[0003] As a cover film as described above, for example, Patent Document 1 discloses a cover film including a support and a coating layer.

[0004] Previous technical literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent No. 10988590 Summary of the Invention

[0007] Technical issues to be solved by the invention

[0008] As described above, after the specimen is sealed using a substrate, a cover film, and a sealing solvent, the cover film must not peel off from the substrate even after long-term storage from the perspective of observability. This property is particularly required when a glass substrate is used as the substrate.

[0009] The present inventors have studied a sealed body produced using a glass substrate and the cover film described in Patent Document 1 and have found that the cover film is easily peeled off from the glass substrate after long-term storage and that there is room for improvement in adhesion.

[0010] Therefore, an object of the present invention is to provide a cover film having excellent adhesion to a glass substrate after a sealed body obtained by bonding the cover film to a glass substrate using a sealing solvent has been stored for a long period of time.

[0011] Means for solving technical problems

[0012] The present inventors have conducted intensive studies to solve the above-mentioned problems and have found that the problems can be solved by the following configuration.

[0013] [1] A cover film comprising a support and a polymer layer containing a polymer, wherein:

[0014] The polar component δP of the Hansen solubility parameter of the polymer layer is 0.0 to 5.1 MPa. 1 / 2The dissolution rate of the polymer layer in xylene is 0.01 to 0.25 g·m -2 ·s -1 The viscosity of a xylene solution having a solid content concentration of 20% by mass obtained by dissolving the polymer layer in xylene at 25° C. is 17 to 200 cP, and the elongation at break of the polymer layer is 10% or more.

[0015] [2] The covering film according to [1], wherein:

[0016] The weight average molecular weight of the polymer is 50,000 to 140,000.

[0017] [3] The covering film according to [1] or [2], wherein:

[0018] The polymer includes at least two repeating units derived from monomers selected from the group consisting of acrylate monomers and methacrylate monomers.

[0019] [4] The covering film according to any one of [1] to [3], wherein

[0020] The above polymer comprises:

[0021] Repeating units derived from ethyl acrylate; and

[0022] at least one repeating unit derived from a monomer selected from the group consisting of methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, 2-methoxyethyl methacrylate, n-butyl methacrylate, and 2-ethylhexyl methacrylate, wherein the content of the repeating unit derived from ethyl acrylate is less than 25% by mass relative to all repeating units of the polymer.

[0023] [5] The covering film according to any one of [1] to [4], wherein

[0024] The polymer includes repeating units derived from an alkyl methacrylate having an alkyl group having 3 or more carbon atoms.

[0025] [6] The covering film according to any one of [1] to [5], wherein

[0026] The thickness of the polymer layer is 5 to 30 μm.

[0027] [7] The covering film according to any one of [1] to [6], wherein

[0028] The weight average molecular weight of the polymer is 90,000 to 120,000.

[0029] [8] The covering film according to any one of [1] to [7], wherein

[0030] The polymer layer further includes at least one compound selected from the group consisting of a silane coupling agent, a hydrolyzate of the silane coupling agent, and a hydrolysis-condensation product of the silane coupling agent.

[0031] [9] The cover film according to any one of [1] to [8], which is used to cover the test object on the substrate.

[0032] Effects of the Invention

[0033] According to the present invention, it is possible to provide a cover film having excellent adhesion to a glass substrate after a sealed body obtained by bonding the cover film to a glass substrate using a sealing solvent has been stored for a long period of time. DETAILED DESCRIPTION

[0034] Hereinafter, the present invention will be described in detail.

[0035] The description of the constituent requirements described below may be made based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0036] In this specification, the numerical range expressed using "to" refers to a range that includes the numerical values ​​recorded before and after "to" as the lower limit and the upper limit. Within the numerical ranges recorded in stages in this specification, the upper limit or lower limit recorded in a certain numerical range can be replaced by the upper limit or lower limit of the numerical range recorded in another stage. Furthermore, within the numerical ranges recorded in this specification, the upper limit or lower limit recorded in a certain numerical range can also be replaced by the values ​​shown in the Examples.

[0037] In this specification, a combination of two or more preferred aspects is a more preferred aspect.

[0038] In this specification, when a plurality of substances corresponding to each component are present in a composition, the amount of each component in the composition or layer refers to the total amount of the plurality of substances present in the composition unless otherwise specified.

[0039] In this specification, "(meth)acrylic acid" is a general term encompassing acrylic acid and methacrylic acid, and means "at least one of acrylic acid and methacrylic acid." Similarly, "(meth)acrylate" means "at least one of acrylate and methacrylate."

[0040] In this specification, unless otherwise specified, the refractive index refers to the refractive index with respect to light of a wavelength of 550 nm measured using NAR-2T manufactured by ATAGO CO., LTD.

[0041] In this specification, unless otherwise specified, the weight average molecular weight (Mw) and number average molecular weight (Mn) are molecular weights obtained as follows: using a gel permeation chromatography (GPC: Gel Permeation Chromatography) analyzer using a column of TSKgel GMHxL, TSKgel G4000HxL, TSKgel G2000HxL and / or TSKgel Super HZM-N (all trade names manufactured by Tosoh Corporation), using THF (tetrahydrofuran) as a solvent, detecting with a differential refractometer, and converting using polystyrene as a standard substance.

[0042] <Cover film>

[0043] Hereinafter, the cover film of the present invention will be described in detail.

[0044] The cover film of the present invention comprises a support and a polymer layer containing a polymer, wherein the polar component δP of the Hansen solubility parameter of the polymer layer is 0.0 to 5.1 MPa. 1 / 2 The dissolution rate of the polymer layer in xylene is 0.01-0.25 g·m -2 ·s -1 The xylene solution having a solid content concentration of 20% by mass obtained by dissolving the polymer layer in xylene has a viscosity of 17 to 200 cP at 25° C., and the elongation at break of the polymer layer is 10% or more.

[0045] The reason why the cover film having the above-mentioned structure can solve the problems of the present invention is not clear, but the present inventors speculate as follows.

[0046] In addition, the mechanism by which the effects are obtained by the following speculation is not limited. In other words, even when the effects are obtained by mechanisms other than the following, they are also included in the scope of the present invention.

[0047] It is believed that the excellent adhesion between the glass substrate and the cover film after the sealed body is stored for a long time is due to the high affinity of the polymer layer to the glass substrate, the filling of the polymer without pores during sealing, and the presence of a sufficient amount of polymer in the sealed area on the glass substrate after sealing to show adhesion.

[0048] The polar component of the Hansen solubility parameter δP in the polymer layer is 0.0~5.1MPa 1 / 2 In this case, the difference in the polar component δP of the Hansen solubility parameter between the polymer layer and the glass substrate is small, and the affinity is excellent.

[0049] The dissolution rate of the polymer layer in xylene is 0.01 g·m -2 ·s -1As shown above, the polymer layer can be dissolved during sealing, the polymer is easily filled without pores, and the dissolution rate of the polymer layer in xylene is 0.25 g·m -2 ·s -1 Then, during sealing, the polymer does not elute to the outside and can be maintained in the sealed area.

[0050] Furthermore, the viscosity of a xylene solution with a solid content concentration of 20% by mass obtained by dissolving the polymer layer in xylene at 25°C is greater than 17 cP, so that the polymer will not be squeezed out during sealing and can be maintained in the sealing area. Furthermore, the viscosity of a xylene solution with a solid content concentration of 20% by mass obtained by dissolving the polymer layer in xylene at 25°C is less than 200 cP, which can ensure the diffusibility of the polymer and easily fill the polymer without pores.

[0051] Furthermore, since the elongation at break of the polymer layer is 10% or more, the polymer layer has excellent followability during sealing, and the polymer can be easily filled without voids.

[0052] It is considered that due to the above-mentioned effects, the cover film of the present invention has excellent adhesion to the glass substrate after a sealed body obtained by bonding the cover film to the glass substrate using a sealing solvent is stored for a long period of time.

[0053] Hereinafter, the adhesion of a sealed body obtained by bonding a cover film to a glass substrate using a sealing solvent after long-term storage to the glass substrate is also referred to as "adhesion after long-term storage", and a case where the adhesion after long-term storage is better is also referred to as "better effect of the present invention".

[0054] [Support]

[0055] The cover film of the present invention comprises a support.

[0056] The support is not particularly limited, but a transparent support is preferred from the perspective of microscopic inspection. In this specification, "transparent" means a transmittance of 60% or greater for visible light (wavelength: 380-780 nm). Transmittance is the ratio of transmitted light to incident light on the support.

[0057] (Material of Support Body)

[0058] The support is not particularly limited, and a known support can be used.

[0059] The content of the specific ester compound described below in the support is preferably 1% by mass or less relative to the total mass of the support.

[0060] Examples of the material constituting the support include cellulose polymers such as triacetate cellulose (TAC), cellulose diacetate, cellulose acetate propionate, and cellulose acetate butyrate; polyester polymers such as aliphatic polyesters; polyolefin polymers such as cycloolefin polymer (COP), polyethylene, and polypropylene; acrylic resins; polycarbonate (PC); and polystyrene, preferably cellulose polymers, acrylic resins, or cycloolefin polymers (COP), and more preferably cellulose triacetate (TAC).

[0061] When the material constituting the support is a polymer, the weight average molecular weight (Mw) thereof is, for example, 10,000 to 1,000,000, and preferably 30,000 to 300,000.

[0062] The above materials may be used alone or in combination of two or more.

[0063] The content of the above materials in the support is preferably more than 50% by mass, more preferably 80% by mass or more, relative to the total mass of the support. The upper limit is not particularly limited and may be 100% by mass.

[0064] Examples of the support composed of cellulose include those described in paragraphs

[0016] to

[0023] of JP-A-2015-227955, the contents of which are incorporated herein.

[0065] (Specific ester compound)

[0066] In the support included in the cover film of the present invention, the content of the specific ester compound is preferably 1% by mass or less relative to the total mass of the support. That is, when the support does not contain the specific ester compound, or when the support contains the specific ester compound, the content is preferably 1% by mass or less relative to the total mass of the support.

[0067] The specific ester compound is an ester compound obtained by condensation reaction of an organic acid or inorganic acid oxyacid and a hydroxyl group-containing compound, wherein at least one of the hydrolyzates (i.e., the organic acid or inorganic acid oxyacid and the compound having a hydroxyl group) has a pKa of 2.5 or less.

[0068] When there are a plurality of pKa values ​​of the ester compound, any one of the plurality of pKa values ​​may be 2.5 or less.

[0069] Examples of the specific ester compound include a phosphoric acid ester compound, a phosphite compound, a sulfonic acid ester compound, and a nitrate ester compound.

[0070] Examples of the hydrolyzate of a specific ester compound having a pKa of 2.5 or less include phosphoric acid generated by hydrolysis of a phosphate ester compound, phosphorous acid generated by hydrolysis of a phosphite ester compound, sulfonic acids such as methanesulfonic acid and benzenesulfonic acid generated by hydrolysis of a sulfonate ester compound, and nitric acid generated by hydrolysis of a nitrate ester compound.

[0071] Examples of the phosphate compound include triphenyl phosphate, biphenyl diphenyl phosphate, bisphenol A bis-(diphenyl phosphate), trimethyl phosphate, triethyl phosphate, diphenyl-2-methacryloylethyl phosphate, tricresyl phosphate, tricresyl phosphate, and tolyl diphenyl phosphate.

[0072] Examples of the phosphite compound include triphenyl phosphite, biphenyl diphenyl phosphite, bisphenol A bis-(diphenyl phosphite), trimethyl phosphite, triethyl phosphite, diphenyl-2-methacryloylethyl phosphite, tricresyl phosphite, trixylene phosphite, and tolylene diphenyl phosphite.

[0073] Examples of the sulfonic acid ester compound include methyl benzenesulfonate, ethyl benzenesulfonate, methyl toluenesulfonate, and ethyl toluenesulfonate.

[0074] As the specific ester compound, a phosphoric acid ester compound is preferred, triphenyl phosphate, biphenyl diphenyl phosphate, or tricresyl phosphate is more preferred, and triphenyl phosphate or biphenyl diphenyl phosphate is further preferred.

[0075] The specific ester compound may be used alone or in combination of two or more. When the support contains two or more specific ester compounds, the total content of the specific ester compounds is preferably 1% by mass or less relative to the total mass of the support.

[0076] The content of the specific ester compound is preferably 0.6% by mass or less, more preferably 0.4% by mass or less, relative to the total mass of the support. The lower limit is not particularly limited and is 0% by mass. It is particularly preferred that the support contain no specific ester compound.

[0077] The content of the specific ester compound contained in the support can be measured by the following measurement method.

[0078] For example, the types and contents of the ester compounds contained in the support can be determined using known measurement methods such as gas chromatography-mass spectrometry (GC / MS). The pKa values ​​of the hydrolyzates generated by hydrolysis of each ester compound contained in the support are calculated based on the structural formula of the ester compound. If a hydrolyzate with a pKa value of 2.5 or less is present, the content of the ester compound generated by the hydrolyzate (the total content if two or more types are present) is the content of the specific ester compound. If no hydrolyzate with a pKa value of 2.5 or less is present, the support does not contain the specific ester compound.

[0079] (Second ester compound)

[0080] The support may contain a second ester compound other than the specific ester compound.

[0081] The second ester compound is not particularly limited as long as it is an ester compound whose hydrolyzate has a pKa of more than 2.5, and examples thereof include carboxylic acid esters composed of carboxylic acid and a hydroxyl group-containing compound.

[0082] Examples of the carboxylic acid ester compound include sugar ester compounds and oligomer A described below.

[0083] -Sugar ester compound-

[0084] Sugar ester compounds are compounds in which some or all of the hydrogen atoms in the hydroxyl groups of sugars are replaced with acyl groups.

[0085] Examples of the sugars include monosaccharides, disaccharides, and polysaccharides, with disaccharides being preferred.

[0086] Examples of the monosaccharides include pentoses such as ribose, deoxyribose, arabinose, and xylose; hexoses such as glucose, galactose, and fructose; and trioses, tetroses, and heptoses.

[0087] Examples of the disaccharides include sucrose, lactose, maltose, trehalose, turanose, and cellobiose, and sucrose is preferred.

[0088] Examples of polysaccharides include glycogen and starch.

[0089] The sugar may have either a chain structure or a ring structure. Examples of the ring structure of the sugar include a furanose ring and a pyranose ring.

[0090] Examples of the acyl group include aliphatic acyl groups such as formyl, acetyl, propionyl, 2-methylpropionyl, 2,2-dimethylpropionyl, and 2-ethylhexanoyl; and aromatic acyl groups such as benzoyl, 1-naphthylcarbonyl, 2-naphthylcarbonyl, and 2-furylcarbonyl.

[0091] The acyl group preferably has 1 to 10 carbon atoms.

[0092] As the sugar ester compound, for example, the compounds described in paragraphs

[0015] to

[0056] of JP-A-2012-031313 can be used.

[0093] -Oligomer A-

[0094] The oligomer A is not particularly limited as long as it is a compound obtained by condensing a dicarboxylic acid and a diol compound, and examples thereof include compounds having a repeating unit represented by the following general formula (1).

[0095] [Chemical Formula 1]

[0096]

[0097] In the general formula (1), X and Y represent a divalent linking group.

[0098] Examples of X include an optionally substituted alkylene group having 2 to 20 carbon atoms, a polyoxyalkylene group, an alkenylene group, a phenylene group, a naphthylene group, and a divalent aromatic heterocyclic group. The alkylene group in the alkylene group, the alkenylene group, and the polyoxyalkylene group may have an alicyclic structure.

[0099] Examples of Y include an optionally substituted alkylene group having 2 to 20 carbon atoms, a polyoxyalkylene group, an alkenylene group, a phenylene group, a naphthylene group, and a divalent aromatic heterocyclic group. The alkylene group in the alkylene group, the alkenylene group, and the polyoxyalkylene group may have an alicyclic structure.

[0100] The divalent linking group represented by X and Y may contain atoms other than carbon atoms, such as oxygen atoms and nitrogen atoms.

[0101] Furthermore, when the oligomer A has a plurality of repeating units represented by the general formula (1), X and Y may be the same or different.

[0102] In the repeating unit represented by general formula (1), X preferably represents a linear or branched divalent linking group having 2 to 10 carbon atoms, and Y preferably represents a divalent linking group having 3 to 12 carbon atoms including a 3- to 6-membered alicyclic structure. The alicyclic structure is more preferably a 5-membered ring or a 6-membered ring.

[0103] As the oligomer A, a compound including a repeating unit represented by the general formula (1A) and having its terminal sealed is preferred.

[0104] [Chemical Formula 2]

[0105]

[0106] In the general formula (1A), X represents a linear or branched divalent linking group having 2 to 10 carbon atoms. R represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, or an aryl group having 6 carbon atoms. m represents an integer of 0 to 4.

[0107] X represents a linear or branched divalent linking group having 2 to 10 carbon atoms.

[0108] X is preferably a linear or branched divalent linking group having 2 to 6 carbon atoms, and more preferably a linear or branched divalent linking group having 2 to 4 carbon atoms.

[0109] Examples of the linear or branched divalent linking group having 2 to 10 carbon atoms include an alkylene group (preferably having 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms, and even more preferably 2 to 4 carbon atoms), an alkynylene group (preferably having 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms, and even more preferably 2 to 4 carbon atoms), and the above-mentioned alkylene groups and alkynylene groups having a heteroatom (for example, an oxygen atom and a nitrogen atom).

[0110] The linear or branched divalent linking group having 2 to 10 carbon atoms may have a substituent.

[0111] Examples of the substituent include an alkyl group, an alkoxy group, a hydroxyl group, a carboxyl group, and a combination thereof.

[0112] R represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, or an aryl group having 6 carbon atoms.

[0113] Examples of the alkyl group having 1 to 8 carbon atoms include methyl, ethyl, propyl, butyl, isobutyl, pentyl, hexyl, octyl and 2-ethylhexyl. An alkyl group having 1 to 4 carbon atoms is preferred, and a methyl group or an ethyl group is more preferred.

[0114] Examples of the alkenyl group having 2 to 8 carbon atoms include vinyl, 1-methylvinyl, 1-propenyl, 2-propenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, and 2-methylenebutyl.

[0115] Examples of the alkynyl group having 2 to 8 carbon atoms include ethynyl, 1-methylethynyl, 1-propynyl, 2-propynyl, 2-methyl-1-propynyl, 2-methyl-2-propynyl, and 2-methylenebutyl.

[0116] Examples of the aryl group having 6 carbon atoms include a phenyl group and a 4-methylphenyl group.

[0117] The group represented by R may have a substituent. Examples of the substituent include the substituents that X may have.

[0118] The number of carbon atoms in the group represented by R does not include the number of carbon atoms in a substituent that the group represented by R may have. For example, an aryl group having 6 carbon atoms includes phenyl and 4-methylphenyl.

[0119] R may form a ring structure. Examples of the ring structure include cyclohexyl, cyclooctyl, bornyl, isobornyl, and norbornyl.

[0120] m represents an integer from 0 to 4.

[0121] m is preferably an integer of 1 to 4, more preferably 1 or 2, and further preferably 1 from the viewpoint of reactivity and raw material procurement.

[0122] The compound containing the repeating unit represented by the above-mentioned general formula (1A) preferably has a terminal structure obtained by reacting the terminal with a monool (or a derivative of a monool and a compound capable of forming an ester bond with the terminal carboxyl group of the polyester) or a monocarboxylic acid (or a derivative of a monocarboxylic acid and a compound capable of forming an ester bond with the terminal hydroxyl group of the polyester).

[0123] For example, a compound containing a repeating unit represented by the general formula (1A) having a carboxyl group at the terminal can react with a monool to seal the terminal with a monool residue. Furthermore, a polyester having a hydroxyl group at the terminal can react with a monocarboxylic acid to seal the terminal with a monocarboxylic acid residue. The residue represents a partial structure of the polyester that has the characteristics of the monomer forming the polyester. For example, a monocarboxylic acid residue formed from a monocarboxylic acid R-COOH is R-CO-, and a monool residue formed from a monoalcohol R-OH is RO-.

[0124] The terminal of the compound containing the repeating unit represented by the above-mentioned general formula (1A) is preferably sealed with an acyl group, and more preferably has a terminal structure obtained by reacting the terminal hydroxyl group with a monocarboxylic acid. The above-mentioned acyl group can be any of a straight chain, a branched chain and a cyclic shape, and preferably does not have any of an aromatic ring and a heterocyclic ring. Among them, the acyl group is preferably a straight chain or branched aliphatic acyl group having 2 to 4 carbon atoms or an alicyclic acyl group having 4 to 12 carbon atoms, more preferably a straight chain aliphatic acyl group having 2 to 3 carbon atoms or an alicyclic acyl group having 4 to 7 carbon atoms, and further preferably a straight chain aliphatic acyl group having 2 carbon atoms or an alicyclic acyl group having 7 carbon atoms.

[0125] Examples of compounds containing a repeating unit represented by the general formula (1A) include those described in paragraphs

[0024] to

[0035] of JP-A-2015-227955, the contents of which are incorporated herein.

[0126] The support may contain a second ester compound other than the sugar ester compound and the oligomer A.

[0127] As other second ester compounds, for example, there can be mentioned adipic acid diesters such as dioctyl adipate, dibutyl adipate and diisobutyl adipate; sebacic acid diesters such as dioctyl sebacate; phthalic acid diesters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dipentyl phthalate, dihexyl phthalate and dicyclohexyl phthalate; tri(2-ethylhexyl) trimellitate; dibutyl maleate; and triacetin.

[0128] Furthermore, for example, the compounds described in paragraphs

[0041] to

[0048] of JP-A-2015-227955 can also be used.

[0129] When the support contains the second ester compound, the second ester compound may be a single type or two or more types.

[0130] When the support contains the second ester compound, the content of the second ester compound is preferably 1 to 30% by mass, more preferably 5 to 15% by mass, relative to the total mass of the support.

[0131] The support may contain other additives in addition to the specific ester compound and the second ester compound. Examples of other additives include compounds represented by the following general formula (2).

[0132] [Chemical Formula 3]

[0133]

[0134] In the general formula (2), R 1 、R 3 and R 5 Each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group or an aromatic group. These alkyl groups, cycloalkyl groups, alkenyl groups and aromatic groups may also have substituents. 1 、R 3 and R 5 Any one of them is an alkyl or cycloalkyl group substituted by a group having a ring structure and in R 1 、R 3 and R 5 The total number of ring structures present in is 3 or more.

[0135] R 1 、R 3 and R 5 The number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 10, further preferably 1 to 5, and particularly preferably 1 to 3.

[0136] However, in the case of an alkyl group substituted with a group having a ring structure, the number of carbon atoms is preferably 7 to 20, more preferably 7 to 12, and even more preferably 7 to 10. The ring structure in the alkyl group having a ring structure may be an aromatic ring (including an aromatic heterocycle) or an aliphatic ring, and is preferably an aromatic hydrocarbon ring or an aliphatic ring.

[0137] The above R 1 、R 3 and R 5 The number of carbon atoms in the cycloalkyl group is preferably 3 to 20, more preferably 3 to 10, further preferably 4 to 8, and particularly preferably 5 or 6.

[0138] The above R 1 、R 3 and R 5 The number of carbon atoms of the alkenyl group in is preferably 2-20, more preferably 2-10, and even more preferably 2-5.

[0139] The above R 1 、R 3 and R 5 The aromatic group in may be an aromatic hydrocarbon group or an aromatic heterocyclic group, and is preferably an aromatic hydrocarbon group. The number of carbon atoms in the aromatic group is preferably 6 to 20, more preferably 6 to 16, and even more preferably 6 to 12. The aromatic group, particularly the aromatic hydrocarbon group, is preferably a phenyl group or a naphthyl group, and more preferably a phenyl group.

[0140] R 1 、R 3 and R 5 Each of the above groups may have a substituent. The above substituent may be further substituted with a substituent. The above substituent is not particularly limited, and examples thereof include the substituents described in paragraphs

[0052] to

[0053] of JP-A-2015-227955.

[0141] R 1 、R 3 and R 5 The substituents that each group may have are preferably alkyl groups, aryl groups, alkoxy groups, alkylthio groups, alkylsulfonyl groups, halogen atoms or acyl groups, more preferably alkyl groups, aryl groups, alkoxy groups or acyl groups, and further preferably alkyl groups or alkoxy groups.

[0142] In the compound represented by the general formula (2), R 1 、R 3 and R 5 Any one of them is an alkyl group or a cycloalkyl group substituted by a group having a ring structure, and preferably any one of them is an alkyl group substituted by a group having a ring structure. 5An alkyl or cycloalkyl group substituted with a group having a ring structure. Here, the ring of the group having a ring structure is preferably a benzene ring, a naphthalene ring, a cyclopentane ring, a cyclohexane ring, or a nitrogen-containing aromatic heterocycle (e.g., a pyrrole ring, a pyrazole ring, an imidazole ring, an oxazole ring, a thiazole ring, a pyridine ring, an indole ring, or an isoindole ring).

[0143] Furthermore, among the compounds represented by the general formula (2), R 1 、R 3 and R 5 At least two of them are alkyl or cycloalkyl groups having a ring structure as a substituent. 1 and R 3 The case where each is independently an alkyl group which may have a substituent, an aromatic group which may have a substituent, or a cycloalkyl group.

[0144] The compound represented by the general formula (2) is more preferably 1 、R 3 and R 5 The total number of ring structures present in the substituent is up to 4.

[0145] R 5 Preferably, the ring structure group or the alkyl group or cycloalkyl group which may be substituted by an acyl group is preferable, the alkyl group substituted by an aryl group, the alkyl group substituted by an acyl group (preferably an alkyl group substituted by an acyl group and an aryl group) or the cycloalkyl group is more preferable, and the alkyl group or cycloalkyl group substituted by an aryl group is further preferable. 5 The preferred alkyl and cycloalkyl groups are as described above.

[0146] Among the compounds represented by the general formula (2), preferred compounds are as follows.

[0147] ·R 1 、R 3 and R 5 A compound wherein any one of the alkyl groups is substituted with an aromatic ring

[0148] As the alkyl group substituted with an aromatic ring, an alkyl group substituted with one or two aryl groups is preferred (when two aryl groups are substituted, they are preferably substituted on the same carbon atom). Also preferred are alkyl groups substituted with an aryl group and an acyl group (preferably an aroyl group).

[0149] ·R 1 、R 3 and R 5 A compound wherein any one of the groups is a cycloalkyl group (preferably a cycloalkyl group)

[0150] In the compound represented by the general formula (2), R 1 、R 3 and R 5More preferably, each of them has one or more ring structures, and even more preferably, each of them has one ring structure.

[0151] The molecular weight of the compound represented by the general formula (2) is preferably 250 to 1200, more preferably 300 to 800, and further preferably 350 to 600.

[0152] For specific examples and synthesis methods of the compound represented by the general formula (2), reference can be made to the contents described in paragraphs

[0041] to

[0078] of Japanese Patent Application Laid-Open No. 2015-227955, which are incorporated herein by reference.

[0153] The types and contents of components contained in the support (e.g., the support material and additives) can be determined by measuring the types and contents of the components contained in the support using a known measurement method such as gas chromatography-mass spectrometry (GC / MS).

[0154] (Properties of the Support)

[0155] The thickness of the support is not particularly limited, but is preferably 50 to 250 μm, more preferably 50 to 150 μm, and further preferably 100 to 150 μm.

[0156] The refractive index of the support is not particularly limited, but may be, for example, 1.44 to 1.60. From the viewpoint of visibility when laminated with a glass substrate, it is preferably 1.46 to 1.56, which is close to that of a slide glass (refractive index 1.52 to 1.56).

[0157] From the perspective of suitability for polarizing microscope observation, the in-plane retardation of the support is preferably 1000 nm or less, more preferably 600 nm or less, further preferably 400 nm or less, and particularly preferably 200 nm or less.

[0158] From the viewpoint of suitability for polarization microscope observation, the retardation in the thickness direction of the support is preferably -300 to 300 nm, more preferably -100 to 100 nm, and even more preferably -50 to 50 nm.

[0159] In this specification, the in-plane retardation Re(λ) at a wavelength of λ and the retardation in the thickness direction Rth(λ) at a wavelength of λ refer to retardations measured by the following method. In addition, unless the wavelength is specifically stated, λ is assumed to be 590 nm.

[0160] Re(λ) and Rth(λ) can be calculated from the measured values ​​of the average refractive index ((nx+ny+nz) / 3) and film thickness (d (μm)) measured at wavelength λ using a phase difference measuring device (KOBRA-21WR, manufactured by Oji Scientific Instruments).

[0161] The surface of the support may be provided with an undercoat layer well known in the photographic light-sensitive material industry. The support may be subjected to surface treatment such as ultraviolet irradiation, corona discharge, or glow discharge.

[0162] The support can be produced from the above-mentioned raw materials by known methods such as solution film formation and melt film formation.

[0163] [Polymer layer]

[0164] The cover film of the present invention comprises a polymer layer containing a polymer, wherein the polar component δP of the Hansen solubility parameter of the polymer layer is 0.0 to 5.1 MPa. 1 / 2 The dissolution rate of the polymer layer in xylene is 0.01-0.25 g·m -2 ·s -1 The xylene solution having a solid content concentration of 20% by mass obtained by dissolving the polymer layer in xylene has a viscosity of 17 to 200 cP at 25° C., and the elongation at break of the polymer layer is 10% or more.

[0165] Hereinafter, after describing each component that can be contained in the polymer layer, the necessary conditions that the polymer layer must satisfy will be described.

[0166] (polymer)

[0167] The polymer layer includes a polymer.

[0168] The polymer is not particularly limited as long as it can form a polymer layer that satisfies the above-mentioned predetermined requirements.

[0169] The polymer preferably swells, and more preferably dissolves, in an organic solvent used as a sealing solvent in an automatic sealing device. The polymer swells or dissolves in the organic solvent, thereby bonding the cover film to the substrate and sealing the specimen.

[0170] Examples of the organic solvent used in the automatic sealing device include xylene, toluene, mesitylene (1,3,5-trimethylbenzene), pseudocumene (1,2,4-trimethylbenzene), trimethylbenzene (1,2,3-trimethylbenzene), durene (1,2,4,5-tetramethylbenzene), anisole, ethyl propionate, amyl acetate, propyl acetate, isopropyl acetate, butyl acetate, methyl lactate, dimethyl carbonate, 1-butanol, 1-propanol, 2- any one of the following solvents: -butanol, 1-pentanol, 2-pentanol, isopentanol, tert-pentanol, neopentyl alcohol, cyclopentanol, 2-hexanol, 4-methyl-2-pentanol, methyl isobutyl ketone, acetylacetone, cyclopentanone, n-butyl ether, 1,2-dimethoxyethane, dioxane, cyclopentyl methyl ether, 1-methoxy-2-propanol, propylene glycol methyl ether acetate, ethyl acetate, methyl acetate, acetone, and methyl ethyl ketone, and a mixed solvent of two or more thereof.

[0171] Furthermore, when using the cover film of the present invention to prepare specimens for microscopic observation, xylene is often used as the sealing solvent. In the preparation of specimens for microscopic observation, specimens obtained by embedding and dissecting in vivo tissues / cells in paraffin wax are often used as the specimen. Therefore, xylene is preferably used because the paraffin wax can be removed during sealing and because of its good affinity with in vivo tissues / cells.

[0172] As the polymer, from the viewpoint of excellent solubility in the above-mentioned organic solvent, a polymer (also referred to as "acrylic resin") containing at least one repeating unit derived from a monomer selected from the group consisting of an acrylate monomer and a methacrylate monomer (also referred to as "(meth)acrylate monomer").

[0173] The acrylic resin may be a homopolymer composed of only one type of repeating unit derived from a (meth)acrylate monomer, or a copolymer containing at least one type of repeating unit derived from a (meth)acrylate monomer.

[0174] The above-mentioned copolymer may be a copolymer containing only at least two or more repeating units derived from (meth)acrylate monomers, or a copolymer containing at least one repeating unit derived from a (meth)acrylate monomer and repeating units derived from a monomer other than a (meth)acrylate monomer (for example, an acrylamide monomer such as dimethylacrylamide and isopropylacrylamide, and a vinyl monomer such as styrene).

[0175] The acrylic resin preferably contains at least two repeating units derived from (meth)acrylate monomers, that is, at least two repeating units derived from monomers selected from the group consisting of acrylate monomers and methacrylate monomers. Furthermore, the acrylic resin preferably consists solely of repeating units derived from (meth)acrylate monomers.

[0176] The content of repeating units derived from (meth)acrylate monomers is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more relative to all repeating units in the polymer. The upper limit is not particularly limited and may be 100% by mass. In addition, the "content of repeating units derived from (meth)acrylate monomers" refers to the total content of repeating units derived from acrylate monomers and repeating units derived from methacrylate monomers contained in the polymer.

[0177] The acrylic resin can be synthesized by a known method, for example, by mixing a (meth)acrylate monomer and, if necessary, an optional monomer and polymerizing the mixture.

[0178] Examples of the (meth)acrylate monomer include alkyl acrylate and alkyl methacrylate.

[0179] The alkyl group in the alkyl acrylate and the alkyl methacrylate may be any of linear, branched, and cyclic, and is preferably linear or branched.

[0180] Furthermore, the alkyl group may have a substituent. Examples of the substituent include an aryl group and a hydroxyl group, with an aryl group being preferred and a phenyl group being more preferred.

[0181] The number of carbon atoms in the alkyl group which may have a substituent in the alkyl acrylate and the alkyl methacrylate is preferably 1 to 15, more preferably 1 to 8, and even more preferably 1 to 5.

[0182] A portion of the methylene group constituting the above-mentioned alkyl group may be substituted with a divalent substituent. Examples of the divalent substituent include -O- and -CO-.

[0183] Specific examples of the acrylic acid ester monomers include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, lauryl acrylate, phenyl acrylate, benzyl acrylate, hydroxyethyl acrylate, and acetoacetoxyalkyl acrylate.

[0184] Among them, as the acrylic acid ester monomer, ethyl acrylate, n-butyl acrylate or phenyl acrylate is preferred, and ethyl acrylate is more preferred.

[0185] Specific examples of the methacrylate monomer include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, lauryl methacrylate, 2-methoxyethyl methacrylate, hydroxyethyl methacrylate, and 2-acetoacetoxyethyl methacrylate.

[0186] Among them, the methacrylate monomer is preferably methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, 2-methoxyethyl methacrylate, n-butyl methacrylate, or 2-ethylhexyl methacrylate; more preferably methyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, 2-methoxyethyl methacrylate, n-butyl methacrylate, or 2-ethylhexyl methacrylate; and even more preferably methyl methacrylate or t-butyl methacrylate.

[0187] The polymer preferably contains repeating units derived from an alkyl methacrylate having an alkyl group with 3 or more carbon atoms, and more preferably contains repeating units derived from an alkyl methacrylate having an alkyl group with 3 or more carbon atoms and repeating units derived from methyl methacrylate.

[0188] The alkyl group in the alkyl methacrylate having an alkyl group having 3 or more carbon atoms may be linear, branched, or cyclic, preferably branched. Furthermore, the alkyl group has 3 or more carbon atoms, preferably 3 to 15, more preferably 3 to 8, and even more preferably 3 to 5.

[0189] Furthermore, the polymer preferably does not contain repeating units derived from ethyl methacrylate.

[0190] One preferred embodiment of the polymer may also include a polymer X comprising repeating units derived from an alkyl acrylate and repeating units derived from an alkyl methacrylate.

[0191] The repeating units derived from an alkyl acrylate in the polymer X are preferably repeating units derived from an alkyl acrylate having an alkyl group having 1 to 7 carbon atoms (preferably 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms). From the viewpoint of achieving a superior fracture toughness value, repeating units derived from ethyl acrylate are more preferred.

[0192] In the polymer X, the repeating unit derived from an alkyl acrylate may be used alone or in combination of two or more.

[0193] In polymer X, the content of repeating units derived from an alkyl acrylate is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to all repeating units of polymer X. The upper limit is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably less than 25% by mass.

[0194] In the polymer X, the repeating unit derived from an alkyl methacrylate may be used alone or in combination of two or more. Preferably, two or more are used in combination.

[0195] The polymer X preferably contains, as the repeating unit derived from an alkyl methacrylate, at least one repeating unit derived from a monomer selected from the group consisting of methyl methacrylate and an alkyl methacrylate having an alkyl group with 3 or more carbon atoms. More preferably, the polymer X contains repeating units derived from methyl methacrylate and repeating units derived from an alkyl methacrylate having an alkyl group with 3 or more carbon atoms. Preferred embodiments of the alkyl methacrylate having an alkyl group with 3 or more carbon atoms are as described above.

[0196] Furthermore, the polymer X also preferably does not include a repeating unit derived from ethyl methacrylate.

[0197] In polymer X, the content of repeating units derived from alkyl methacrylate is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably more than 75% by mass, relative to all repeating units of polymer X. The upper limit is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.

[0198] One preferred embodiment of the polymer X is a polymer Y comprising repeating units derived from polyethyl acrylate and at least one repeating unit derived from a monomer selected from the group consisting of methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, 2-methoxyethyl methacrylate, n-butyl methacrylate, and 2-ethylhexyl methacrylate.

[0199] In polymer Y, the content of repeating units derived from ethyl acrylate is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to all repeating units of polymer Y. The upper limit is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably less than 25% by mass.

[0200] One preferred embodiment of the polymer X is a polymer Z comprising repeating units derived from ethyl acrylate and repeating units derived from an alkyl methacrylate having an alkyl group having 3 or more carbon atoms.

[0201] In polymer Z, the content of repeating units derived from ethyl acrylate is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, relative to all repeating units in polymer Z. The upper limit is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably less than 25% by mass.

[0202] The details and preferred embodiments of the alkyl methacrylate having an alkyl group having 3 or more carbon atoms in the polymer Z are as described above.

[0203] In polymer Z, the content of repeating units derived from alkyl methacrylate having an alkyl group having 3 or more carbon atoms is preferably 10 to 50% by mass, more preferably 20 to 40% by mass, and even more preferably 25 to 35% by mass based on all repeating units in polymer Z.

[0204] The polymer Z may contain repeating units other than those described above, and preferably further contains repeating units derived from another alkyl methacrylate other than the alkyl methacrylate having an alkyl group having 3 or more carbon atoms (e.g., methyl methacrylate and ethyl methacrylate), and more preferably contains repeating units derived from methyl methacrylate.

[0205] In the polymer Z, the content of the repeating units derived from other alkyl methacrylates is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 40 to 55% by mass, based on all the repeating units of the polymer Z.

[0206] The weight average molecular weight (Mw) of the polymer is preferably 10,000 to 500,000, more preferably 50,000 to 140,000, further preferably 80,000 to 120,000, and particularly preferably 90,000 to 120,000.

[0207] Among these, the weight average molecular weight of the polymer having repeating units derived from an alkyl methacrylate having an alkyl group having 3 or more carbon atoms is preferably 50,000 to 140,000, more preferably 90,000 to 120,000.

[0208] The value of the polar component δP of the Hansen solubility parameter of the polymer layer is not particularly limited as long as it satisfies the prescribed necessary conditions, but is preferably 0.0 to 5.1 MPa. 1 / 2 , more preferably 1.0 to 4.5 MPa 1 / 2 .

[0209] The polar component δP of the Hansen solubility parameter of the polymer can be calculated using a method for calculating the polar component δP of the Hansen solubility parameter of the polymer layer described later.

[0210] The polymer may be used alone or in combination of two or more. When two or more polymers are used in combination, they are preferably used in such a ratio that turbidity does not occur in the mixed dried film.

[0211] The content of the polymer in the polymer layer is not particularly limited, but is preferably 50% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more relative to the total mass of the polymer layer. The upper limit may be 100% by mass.

[0212] (Silane coupling agents)

[0213] The polymer layer may contain at least one selected from the group consisting of a silane coupling agent, a hydrolyzate of a silane coupling agent, and a hydrolysis-condensation product of a silane coupling agent (hereinafter, these are collectively referred to as “silane coupling agents”).

[0214] The hydrolyzate of the silane coupling agent refers to a compound produced by hydrolysis of the hydrolyzable groups in the silane coupling agent. It may be a complete hydrolyzate in which all the hydrolyzable groups in the silane coupling agent are hydrolyzed, a partial hydrolyzate in which some of the hydrolyzable groups are decomposed, or a mixture thereof.

[0215] The hydrolysis condensate of the silane coupling agent refers to a compound formed by condensation of the hydrolyzate of the silane coupling agent, and may be a compound formed by condensation of all hydrolyzed groups of the hydrolyzate, a compound formed by condensation of only a part of the groups, or a mixture thereof.

[0216] When the polymer layer contains a silane coupling agent, even if the cover film is stored in a roll form, the occurrence of blocking between the polymer layer and the back surface of the support (the surface of the support opposite to the surface on which the polymer layer is formed) can be suppressed, and this is preferred from the viewpoint of improving storage properties over time.

[0217] The type of silane coupling agent is not particularly limited, but preferably a silane coupling agent having two or more different reactive groups in the molecule, at least one of the reactive groups being a reactive group chemically bonded to an inorganic substance and at least one of the reactive groups being a reactive group chemically bonded to an organic material.

[0218] Examples of the silane coupling agent include silane coupling agents represented by the following general formula.

[0219] X-Si(R 1 )3

[0220] X represents a group having a reactive group. Examples of the reactive group include a vinyl group, an epoxy group, an amino group, a (meth)acrylic group, and a mercapto group.

[0221] More specifically, X can be represented by R2 -L- represented by the group. 2 represents a reactive group, and L represents a divalent linking group (preferably an alkylene group which may contain a heteroatom (eg, an oxygen atom)).

[0222] R 1 represents a hydrolyzable group. A hydrolyzable group is a group that directly bonds to Si (silicon atom) and undergoes hydrolysis and / or condensation reactions. Examples of hydrolyzable groups include alkoxy groups, halogen atoms, acyloxy groups, alkenyloxy groups, and isocyanate groups.

[0223] Examples of the silane coupling agent include vinyltrichlorosilane, vinyltri(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-(methacryloxypropyl)trimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane. Among them, the polymer layer preferably contains at least one selected from the group including γ-glycidoxypropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane, more preferably contains at least one selected from the group including γ-glycidoxypropyltrimethoxysilane and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and further preferably contains γ-glycidoxypropyltrimethoxysilane.

[0224] The silane coupling agents may be used alone or in combination of two or more.

[0225] The content of the silane coupling agent in the polymer layer is preferably 0.1 mg / m2 relative to the area of ​​the polymer layer. 2 More preferably 5 to 25 mg / m 2 .

[0226] The silane coupling agent in the polymer layer may be uniformly present throughout the polymer layer or unevenly present on any surface of the polymer layer. When the silane coupling agent is unevenly present on the surface of the polymer layer, the surface may be the surface of the polymer layer on the side facing the support or the surface of the polymer layer on the side opposite to the support.

[0227] (Plasticizer)

[0228] The polymer layer of the present invention may contain a plasticizer.

[0229] Inclusion of a plasticizer is preferred from the viewpoints of improving the compatibility of the polymer layer with a solvent (xylene or the like), increasing the dissolution rate of the polymer layer when in contact with the solvent, and improving the brittleness of the polymer layer.

[0230] The type of plasticizer is not particularly limited, but preferably one with high compatibility with the polymer used. For example, it is preferred that the Hansen solubility parameter distance between the plasticizer and the polymer be small.

[0231] Examples of the plasticizer include phosphoric acid esters, carboxylic acid esters, and ethylene glycol compounds.

[0232] Examples of the phosphoric acid ester include triphenyl phosphate, bisphenol A bis-(diphenyl phosphate), trimethyl phosphate, triethyl phosphate, and diphenyl-2-methacryloylethyl phosphate.

[0233] Examples of the carboxylic acid ester include adipates such as dioctyl adipate, dibutyl adipate, diisobutyl adipate, ADEKASIZER LV-808 (manufactured by ADEKA CORPORATION), POLYSIZER W-242, W-230-H, W-1020-EL, and W-1430-EL; phthalates such as diisononyl phthalate, bis(2-ethylhexyl) phthalate, and isodecyl phthalate; sebacic acid esters such as dioctyl sebacate; trimellitic acid esters such as tris(2-ethylhexyl) trimellitic acid, ADEKASIZER C series (e.g., C-8, etc., manufactured by ADEKA CORPORATION) and MONOSIZER W-705 (manufactured by DICCORPORATION); and ADEKASIZER UL-80 and UL-100 (manufactured by ADEKA CORPORATION). pyromellitic acid esters such as ADEKASIZER UL-8 (manufactured by ADEKA CORPORATION); dipentaerythritol esters such as MONOSIZER W-150 (manufactured by DIC CORPORATION); carboxylic acid esters having an epoxy group such as MONOSIZER W-150 (manufactured by DIC CORPORATION); benzoic acid esters such as MONOSIZER PB-3A (manufactured by DIC CORPORATION); dibutyl maleate; glyceryl triacetate, etc.

[0234] Examples of the ethylene glycol compound include polyethylene glycol, triethylene glycol bis(2-hexyl acetate), and diethylene glycol dibenzoate.

[0235] As the plasticizer, deep eutectic solvents (DES) can also be preferably used. Deep eutectic solvents are solvents containing a hydrogen bond acceptor compound and a hydrogen bond donor compound, and the mixing of the hydrogen bond acceptor compound and the hydrogen bond donor compound causes the eutectic melting point to be lowered significantly.

[0236] Examples of hydrogen bond accepting compounds include quaternary ammonium compounds, phosphorus compounds, metal salts, amino acids, and polycarboxylic acids. Examples of hydrogen bond donating compounds include alcohol compounds, sugars, carboxylic acids, and amine compounds.

[0237] Deep eutectic solvents are described, for example, in paragraphs

[0025] to

[0048] of U.S. Patent Application Publication No. 2018 / 0194913 and Japanese Patent Application Laid-Open No. 2020-105336, and these descriptions are incorporated into this specification.

[0238] The plasticizer may be used alone or in combination of two or more.

[0239] From the viewpoint of further exerting the effect of the plasticizer and further suppressing the generation of chips during cutting, the content of the plasticizer is preferably 0.5 to 20 mass %, more preferably 1 to 15 mass %, and even more preferably 3 to 10 mass % relative to the total mass of the polymer layer.

[0240] (Thickener)

[0241] The polymer layer may comprise a thickener.

[0242] The type of thickener is not particularly limited, but examples thereof include high molecular weight compounds such as polysaccharides, celluloses, acrylic acid, polyvinyl alcohol, glycols and terpenes, inorganic particles such as silica particles and titanium dioxide particles, and organic particles composed of polymers such as PMMA (polymethyl methacrylate), preferably cellulose or silica particles.

[0243] From the viewpoint of being able to suppress the bleeding (migration) of the hydrophilic material from a member in contact with the polymer layer, the surfaces of the inorganic particles are preferably subjected to a hydrophobic treatment.

[0244] The size of inorganic particles and organic particles is not particularly limited. If too large, scattering is likely to occur, and sometimes microscopic variation occurs. Therefore, the average secondary particle size of inorganic particles and organic particles (the average particle size of the agglomerates of inorganic particles and organic particles) is preferably less than 1 μm. The lower limit is not particularly limited and can be more than 1 nm. In addition, the average secondary particle size of inorganic particles and organic particles is according to dynamic light scattering, and can be measured using particle size measuring device (OTSUKA ELECTRONICS CO., LTD manufactures " nanoSAQLA ").

[0245] Furthermore, from the viewpoint of preventing scattering, the refractive index of the inorganic particles and the organic particles is preferably close to the refractive index of the polymer layer. More specifically, the refractive index of the inorganic particles and the organic particles is preferably 1.40 to 1.60.

[0246] The thickener may be used alone or in combination of two or more.

[0247] From the viewpoint of further exerting the thickener effect and further suppressing the generation of chips during cutting, the thickener content is preferably 0.5 to 20 mass %, more preferably 1 to 15 mass %, and even more preferably 3 to 10 mass % relative to the total mass of the polymer layer.

[0248] (Properties of polymer layer)

[0249] -Polar component of Hansen solubility parameter δP-

[0250] The polar component δP of the Hansen solubility parameter of the polymer layer (hereinafter also referred to as “polar component δP”) is 0.0 to 5.1 MPa. 1 / 2 From the viewpoint of achieving more excellent effects of the present invention, the polar component δP of the polymer layer is more preferably 1.0 to 4.5 MPa. 1 / 2 .

[0251] By setting the polarity component δP of the polymer layer within the above range, the difference between the polarity component δP of the glass substrate becomes smaller, the affinity between the glass substrate and the polymer layer is improved, and as a result, the effect of the present invention is excellent. Specifically, the absolute value of the difference between the polarity component δP of the polymer layer and the polarity component δP of the glass substrate is preferably 2.6 MPa. 1 / 2 Below, more preferably 2.0 MPa 1 / 2 Below. The lower limit is not particularly limited and is 0 MPa 1 / 2 above.

[0252] In addition, as the polar component δP of the glass substrate, a value described in a known document can be used, for example, 2.5 MPa described in HP ("Hansen Solubility Parameters (HSP) Application Notes", https: / / pirika.com / ENG / HSP / E-Book / Chap10.html) of pirika.com. 1 / 2 .

[0253] Hansen solubility parameters (HSP) divide the solubility of a substance into three components: the dispersion term δD, the polar component δP, and the hydrogen bonding term δH. These parameters are expressed in three-dimensional space (Hansen space). The polar component δP represents the effect of dipole forces. The dispersion term δD represents the effect of dispersion forces, and the hydrogen bonding term δH represents the effect of hydrogen bonding forces. Details of the Hansen solubility parameters are described in Charles M. Hansen's "Hansen Solubility Parameters: A Users Handbook" (CRC Press, 2007).

[0254] The Hansen solubility parameter of the polymer layer can be determined by the following Hansen sphere method.

[0255] The polymer layer is separated from the support of the covering film. Next, 1 g of the separated polymer layer is put into 100 g of a solvent with a known Hansen solubility parameter, stirred for 24 hours, and visually confirmed. If there is no undissolved matter, it is judged to be dissolved, and if there is residual undissolved matter, it is judged to be insoluble. The above-mentioned solubility determination is performed on a variety of solvents. The coordinates of the above-mentioned solvents are plotted on the Hansen space, and a sphere (Hansen sphere) is obtained that includes the drawing of the solvent in which the polymer layer is dissolved and does not include the solvent in which the polymer layer is not dissolved. The center coordinates of the obtained Hansen sphere are obtained as the Hansen solubility parameters (dispersion term δD, polar component δP, hydrogen bond term δH) of the polymer layer. The value of the polar component δP is adopted as the polar component δP of the polymer layer. In addition, the above-mentioned solubility determination is performed at 25°C.

[0256] For the calculation of the Hansen sphere, for example, Hansen Solubility Parameters in Practice (HSPiP) (version: 5.1.08) software for calculating the Hansen solubility can be used.

[0257] Solvents with known Hansen solubility parameters in the Hansen sphere method can be appropriately selected according to the composition of the polymer layer. The number of solvents used for solubility determination is not particularly limited as long as the polar component δP can be determined, but is, for example, 20 or more, preferably 30 or more.

[0258] -Dissolution rate in xylene-

[0259] The dissolution rate of the polymer layer in xylene is 0.01-0.25 g·m -2 ·s -1 From the viewpoint of achieving the best effects of the present invention, the dissolution rate of the polymer layer in xylene is preferably 0.05 to 0.20 g·m -2 ·s-1 .

[0260] The dissolution rate of the above polymer layer in xylene (g·m -2 ·s -1 ) is determined by the following steps.

[0261] Cut the covering film having a support and a polymer layer containing a polymer into a specified size (24 mm in length × 120 mm in width) to obtain a sample for measurement to measure its mass (mass before immersion). Immerse the above-mentioned sample for measurement in 1200 mL of xylene placed in a container for a certain period of time. After immersion, gently remove the covering film from the container and thoroughly dry the xylene. Measure the mass after drying (mass after immersion) and calculate the difference between the mass before immersion and the mass after immersion. Divide the mass difference (g) by the area of ​​the sample for measurement (m 2 ) and immersion time (s) to calculate the dissolution rate (g·m -2 ·s -1 ).

[0262] The immersion time may be appropriately set to a time that the polymer layer does not completely dissolve, and is preferably 30 to 300 seconds, for example 60 seconds. The temperature and time for drying xylene may be appropriately set, for example 150°C for 60 minutes.

[0263] -Viscosity-

[0264] The viscosity of a xylene solution having a solid content concentration of 20% by mass obtained by dissolving the polymer layer in xylene at 25° C. is 17 to 200 cP. From the viewpoint of further improving the effects of the present invention, the viscosity is preferably 30 to 150 cP, more preferably 30 to 75 cP.

[0265] The above viscosity (cP) is measured by the following procedure.

[0266] The polymer layer is separated from a cover film comprising a support and a polymer layer containing a polymer, and the mass of the resulting polymer layer is measured. The resulting polymer layer is dissolved in xylene to prepare a xylene solution having a solids concentration of 20% by mass. In other words, the xylene solution contains a predetermined amount of components constituting the polymer layer as solids.

[0267] The viscosity (cP) of the xylene solution at a measurement temperature of 25° C. was measured using an E-type viscometer (VISCOMETER RE-85L, manufactured by TOKI SANGYO CO., LTD.).

[0268] -Elongation at break-

[0269] The polymer layer contained in the cover film of the present invention has an elongation at break of 10% or greater. From the perspective of achieving even greater effects of the present invention, the elongation at break of the polymer layer is preferably 15% or greater. The upper limit of the elongation at break of the polymer layer is not particularly limited, but is generally 100% or less, and more preferably 50% or less.

[0270] The elongation at break (%) is measured by the following procedure.

[0271] The cover film is heated under vacuum conditions. The vacuum is preferably 75 mmHg or less. The heating conditions can be appropriately selected based on the composition and properties of the polymer layer. The heating temperature is preferably 50 to 150°C, for example, 100°C. The heating time is preferably 1 to 24 hours, for example, 4 hours.

[0272] Thereafter, the support and the polymer layer are separated to obtain a film-like polymer layer. In this case, if the support can be peeled off from the polymer layer, the film-like polymer layer obtained by peeling off the support from the polymer layer can be used. If the support cannot be peeled off from the polymer layer, the polymer layer separated from the support by cutting or the like can be used to produce a new film-like polymer layer by a casting method or the like.

[0273] Thereafter, the humidity was adjusted at 23° C. and 50% for 24 hours. The film-like polymer layer after the humidity adjustment was processed into a predetermined size (10 mm in width, 50 mm in length, and 20 μm in thickness) using a punching tool or the like to prepare a sample for a tensile test.

[0274] Tensionron RTF-1310 manufactured by A&D Company, Limited was used and the tensile test was carried out at a stretching speed of 2 mm·min at 23°C and 50% RH. -1 The tensile test sample was stretched in the longitudinal direction, and the elongation at break (%) was calculated based on the obtained stress-strain curve.

[0275] The above measurement was performed five times, and the arithmetic mean value was adopted as the breaking elongation (%) of the polymer layer.

[0276] The total content of the solvent contained in the film-like polymer layer for measuring the elongation at break is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, relative to the total mass of the polymer layer. The lower limit is not particularly limited, but is preferably 0% by mass.

[0277] The heating conditions under the vacuum conditions are preferably selected so that the total content of the solvent contained in the film-like polymer layer after heating satisfies the preferred range described above.

[0278] The total content of the solvents contained in the polymer layer can be determined by measuring the types of solvents contained in the polymer layer and the content of each solvent using a known measurement method such as gas chromatography-mass spectrometry (GC / MS).

[0279] -thickness-

[0280] The thickness of the polymer layer is not particularly limited, but is preferably 1 to 100 μm, more preferably 5 to 40 μm, and further preferably 5 to 30 μm.

[0281] -Refractive index-

[0282] From an optical viewpoint when observed under a microscope, the refractive index of the polymer layer is preferably 1.45 to 1.56, which is close to that of glass (refractive index 1.52 to 1.56), more preferably 1.46 to 1.56, and even more preferably 1.47 to 1.56.

[0283] [Other layers]

[0284] The cover film may have layers other than the support and the polymer layer.

[0285] As another layer, a backing layer can be mentioned.

[0286] The backing layer can be provided on the back side of the support (the side opposite to the side provided with the polymer layer) for the purpose of preventing scratches on the surface of the cover film, more reliably preventing blocking during storage in an extremely high temperature environment, or maintaining the curling balance of the cover film.

[0287] Examples of the constituent material of the backing layer include synthetic polymers having a high glass transition temperature, such as polystyrene and polymethyl methacrylate, and gelatin.

[0288] The total thickness of the polymer layer and the support in the cover film is not particularly limited, but is preferably 250 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less from the perspective of ease of handling and microscopic inspection during microscopic observation. The lower limit is preferably 50 μm or greater from the perspective of ease of handling, such as resistance to bending, and sealing properties.

[0289] <Method for producing cover film>

[0290] The method for producing the cover film is not particularly limited as long as it is a method for producing a laminate having at least a support and a polymer layer, but it is preferred that the polymer layer be provided on the surface of the support.

[0291] The method for forming the polymer layer on the support is not particularly limited, and examples thereof include coating with a coater or sprayer, casting, and transfer. Among these, it is preferred to form the polymer layer by applying a coating solution prepared by dissolving the constituent components of the polymer layer in a solvent onto the support and then drying the coating.

[0292] The type of solvent used in the coating solution can be appropriately selected from the viewpoints of the solubility of the constituent components of the polymer layer, wettability to prevent repulsion on the support, drying speed, surface tension, etc. Examples of the solvent used in the coating solution include toluene, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, and xylene.

[0293] If a material that can dissolve the surface of the support or a material that can dissolve low molecular weight components such as plasticizers contained in the support is used as the solvent used in the coating liquid, the interfacial mixing of the constituent components of the polymer layer and the support will be promoted, the adhesion between the polymer layer and the support will be improved, the peeling of the polymer layer can be prevented, and the generation of chips during cutting can be suppressed.

[0294] From the above viewpoints, the coating liquid used for forming the polymer layer preferably contains a solvent selected from the group consisting of ethyl acetate and butyl acetate, and more preferably contains ethyl acetate.

[0295] The content of the solvent selected from the group consisting of ethyl acetate and butyl acetate in the coating liquid is not particularly limited, but from the perspective of further suppressing the generation of chips during cutting of the cover film, it is preferably 40% by mass or greater, and more preferably 50% by mass or greater, relative to the total mass of the solvent contained in the coating liquid. The upper limit is not particularly limited and may be 100% by mass or less, but from the perspective of further suppressing deformation of the substrate, it is preferably 90% by mass or less.

[0296] It is preferable to perform a drying step in which, after the coating liquid is applied onto the support to form a coating film, the obtained coating film is dried to remove the solvent from the coating film.

[0297] Examples of drying treatments performed in the drying step include a method of leaving the coating film at room temperature (23°C) for a predetermined period of time (e.g., natural drying), air drying by blowing gas onto the coating film, heat drying by heating the coating film using a heating member such as an oven, a hot plate, or a heated roller, and combinations thereof. Preferably, at least one of air drying and heat drying is performed in the drying step, and a combination of air drying and heat drying is more preferred.

[0298] The temperature of the gas used in air drying is not particularly limited, but is preferably 50 to 160°C, more preferably 80 to 140°C. The airflow velocity (wind speed) during air drying is not particularly limited, but is preferably 2 to 15 m / s, more preferably 3 to 10 m / s. The air drying treatment time is preferably 0.5 to 5 minutes. Examples of the gas used in air drying include air and nitrogen.

[0299] The temperature for heat drying is not particularly limited, but is preferably 50 to 160° C. The heating time is preferably 0.5 to 5 minutes.

[0300] The method for forming a polymer layer containing silane coupling agents is not particularly limited, and examples thereof include: a first method in which a silane coupling agent is preliminarily added to a coating liquid for forming a polymer layer, the coating liquid containing a polymer and a silane coupling agent is applied to a support, and the coating film is dried to form a polymer layer; a second method in which a coating liquid prepared by dissolving a silane coupling agent in a solvent is applied to the surface of a coating film containing a polymer formed on a support, and the coating film is dried to form a polymer layer; and a third method in which a coating liquid containing a polymer and a coating liquid prepared by dissolving a silane coupling agent in a solvent are simultaneously applied (multilayer coating) to a support, and the coating film is dried to form a polymer layer.

[0301] In the above-mentioned first to third methods, when a silane coupling agent is used as a raw material, a hydrolysis reaction and a condensation reaction of the silane coupling agent may be carried out during the formation.

[0302] From the perspective of being able to efficiently utilize a small amount of silane coupling agents, the second method or the third method is preferred. In the polymer layer containing a silane coupling agent formed by the second method or the third method, the silane coupling agent tends to be unevenly present on the surface of the polymer layer opposite to the support.

[0303] The solvent for the coating solution prepared by dissolving the silane coupling agent in the solvent used in the second and third methods is not particularly limited as long as it can dissolve the silane coupling agent. For example, the solvents listed as solvents that can dissolve the above-mentioned polymers can be used. Among them, ethyl acetate is preferred from the viewpoint of better adhesion improvement.

[0304] <Application>

[0305] The cover film of the present invention can be preferably used as a cover film for covering an object to be examined on a substrate. It can be more preferably used for preparing specimens for microscopic observation, and can be even more preferably applied to microscopes equipped with automatic sealing devices. The substrate is preferably a glass substrate.

[0306] The use of the cover film of the present invention is not limited to the above-mentioned uses, and it can be used for, for example, sealing of a thin film on a glass substrate and protection of a lower layer by lamination.

[0307] Example

[0308] Hereinafter, the present invention will be described in more detail based on examples.

[0309] The materials, usage amounts, ratios, treatment contents, and treatment steps shown in the following examples can be appropriately modified without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be limitedly interpreted by the following examples.

[0310] <Production of Cover Film>

[0311] [Fabrication of polymer layer]

[0312] The support body 1 was produced according to the following steps.

[0313] (Preparation of Core Layer Cellulose Acylate Dope)

[0314] The following components were charged into a mixing tank, and the mixture was stirred to dissolve the components, thereby preparing a cellulose acetate solution A1 serving as a core layer cellulose acylate dope.

[0315] 100 parts by mass of cellulose acetate with a degree of acetyl substitution of 2.88

[0316] A mixture containing the oligomer A-1 described below and the compound A-2 described below, wherein the mass ratio of the content of the oligomer A-1 to the content of the compound A-2 {(content of the oligomer A-1):(content of the compound A-2)} is 4:1

[0317] 430 parts by mass of dichloromethane

[0318] 64 parts by mass of methanol

[0319] The amount of the mixture added to the cellulose acetate solution A1 was adjusted so that the total content of oligomer A-1 and compound A-2 contained in the support 1 prepared by the method described below using the cellulose acetate solution A1 and the cellulose acetate solution A2 described later would be 12.3% by mass relative to the total mass of the support 1.

[0320] [Chemical Formula 4]

[0321]

[0322] Oligomer A-1 is a condensate of 1,2-cyclohexanedicarboxylic acid and ethylene glycol, namely, an aliphatic carboxylate oligomer. It has a terminal structure in which the hydrogen atoms of both terminal hydroxyl groups are substituted (capped) with cyclohexanoyl groups. The number average molecular weight of oligomer A-1 is 850.

[0323] (Preparation of Outer Layer Cellulose Acylate Dope)

[0324] To 90 parts by mass of the cellulose acetate solution A1 (core layer cellulose acylate dope) was added 10 parts by mass of a matting agent solution B1 having the following composition to prepare a cellulose acetate solution A2 serving as an outer layer cellulose acylate dope.

[0325] -Composition of matting agent solution-

[0326] 2 parts by mass of silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)

[0327] 76 parts by mass of dichloromethane

[0328] 11 parts by mass of methanol

[0329] 1 part by mass of cellulose acetate solution A1 (core layer cellulose acylate dope)

[0330] (Production of Support 1)

[0331] The core layer cellulose acylate dope and the outer layer cellulose acylate dope were filtered through filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm, respectively. The filtered core layer cellulose acylate dope and the filtered outer layer cellulose acylate dope were simultaneously cast from the casting port of a belt casting machine onto a drum surface having a surface temperature of 20°C in three layers, thereby forming a laminated film having a core layer sandwiched between two outer layers.

[0332] Next, the laminated film was peeled from the drum and secured at both ends of the laminated film in the width direction with tenter clips. The laminated film, secured by the tenter clips, was stretched in the width direction at a stretching ratio of 1.1x while being dried. The laminated film was then passed between the rollers of a heat treatment apparatus for further drying, thereby producing a support 1.

[0333] The lowest pKa among the pKas of the hydrolyzates contained in the support 1 is pKa 4.0, which is possessed by at least one of the hydrolyzates of the compound A-2. Therefore, the support 1 does not contain the specific ester compound.

[0334] The support 1 is a transparent support, and corresponds to an in-plane retardation Re of <200 nm at a wavelength of 590 nm and a retardation Rth in the thickness direction of -50 to 50 nm at a wavelength of 590 nm.

[0335] [Fabrication of polymer layer]

[0336] (Synthesis of Polymers)

[0337] Polymer 1 was synthesized according to the following steps.

[0338] To a mixture of 38 parts by mass of toluene and 25 parts by mass of ethyl acetate was added a mixture of 20 parts by mass of ethyl acrylate, 50 parts by mass of methyl methacrylate, 30 parts by mass of t-butyl methacrylate, 98 parts by mass of toluene, 66 parts by mass of ethyl acetate, and 0.7 parts by mass of azoisobutyronitrile over 2 hours at 80°C under a nitrogen atmosphere. The resulting mixture was then reacted for 2 hours while maintaining the temperature at 80°C. Subsequently, 1.2 parts by mass of azoisobutyronitrile was added to the mixture, and a polymerization reaction was carried out at 90°C to produce a polymer 1 having a predetermined weight-average molecular weight, thereby obtaining a polymer solution 1. The weight-average molecular weight (Mw) of the resulting polymer was 100,000.

[0339] The polymers used in each example and each comparative example are shown in the table below. The ratio of each monomer is a mass ratio, and each polymer was synthesized using the monomers according to the above-mentioned procedure to achieve the ratio.

[0340] (Preparation of coating solution for forming polymer layer)

[0341] Ethyl acetate and toluene were added to the polymer solution 1 and mixed so that the polymer solid content concentration became 20% by mass and the ratio of ethyl acetate to the total solvent became 78% by mass, thereby obtaining a polymer layer coating solution 1.

[0342] The polymer solutions used in the examples and comparative examples were prepared according to the above steps.

[0343] Separately, 109.89 parts by mass of ethyl acetate were added to 0.11 parts by mass of a silane coupling agent KBM403 (γ-glycidoxypropyltrimethoxysilane) (Shin-Etsu Chemical Co., Ltd.), thereby obtaining a silane coupling agent coating liquid 1.

[0344] [Formation of polymer layer]

[0345] The polymer layer coating liquid 1 and the silane coupling agent coating liquid 1 were applied to the support 1 by extrusion multilayer coating to form a coating film. The coating amount of the polymer layer coating liquid 1 was adjusted so that the film thickness after drying was 19 μm, and the coating amount of the silane coupling agent coating liquid 1 was adjusted so that the coating concentration of the silane coupling agent relative to the surface area of ​​the transparent support was 13.5 mg / m 2 amount.

[0346] The formed coating film was dried by blowing warm air at 100°C at a speed of 3.2 m / s for 2 minutes, followed by heating and drying in an oven to volatilize the solvent. This produced a cover film 1 comprising a transparent support and a polymer layer having a silane coupling agent layer on the surface. The total thickness of the transparent support and polymer layer in cover film 1 was 137 μm.

[0347] The cover films used in the examples and comparative examples were produced according to the above-described procedures.

[0348] <Measurement of Physical Properties of Polymer Layer>

[0349] The physical properties of the polymer layer in each cover film obtained by the above method were measured by the following methods.

[0350] [Polar component of the Hansen solubility parameter of the polymer layer δP]

[0351] The polar component δP of the polymer layer is determined using the Hansen sphere method described above.

[0352] Specifically, 1 g of the polymer layer obtained by peeling off the support 1 was put into 100 g of a solvent with a known Hansen solubility parameter adjusted to 25°C, stirred for 24 hours, and then visually confirmed. If no undissolved matter could be confirmed, it was deemed to be dissolved; if the undissolved matter could be confirmed, it was deemed to be insoluble, and the solubility at 25°C was determined. The solubility was determined for 30 solvents. The coordinates of the above-mentioned solvents were plotted on the Hansen space, and a sphere (Hansen sphere) containing the drawing of the solvent in which the polymer layer is dissolved and excluding the drawing of the solvent in which the polymer layer is not dissolved was obtained using HSPiP. The center coordinates of the obtained Hansen sphere were used as the Hansen solubility parameters (dispersion term δD, polar component δP, hydrogen bond term δH) of the polymer layer, and the value of the polar component δP was adopted as the polar component δP of the polymer layer.

[0353] [Xylene dissolution rate of polymer layer]

[0354] The film was cut into a size of 24 mm in length and 120 mm in width, and the cut film was immersed in 1200 mL of xylene in a stainless steel container for 60 seconds. The weight of the film before and after immersion was measured, and the weight change before and after immersion (g) was divided by the area of ​​the film (m2). 2 ) and immersion time (s), the dissolution rate (g·m -2 ·s -1 ) In addition, the xylene drying after immersion was performed at 150° C. for 60 minutes.

[0355] [Viscosity of polymer layer]

[0356] The polymer layer was dissolved in xylene to prepare a xylene solution having a solid content concentration of 20%. The viscosity (cP) of the xylene solution of the polymer layer at 25°C was measured using an E-type viscometer (VISCOMETER RE-85L, manufactured by TOKI SANGYO CO., LTD.).

[0357] [Elongation at break of polymer layer]

[0358] After heating the cover film at 100°C under vacuum for 4 hours, the support 1 was peeled from the polymer layer to obtain a film-like polymer layer. The resulting film-like polymer layer was conditioned at 23°C and 50% RH for 24 hours and then punched out using a punching tool to produce a sample for tensile testing with a width of 10 mm and a length of 50 mm.

[0359] Tension testing was performed using Tensionron RTF-1310 manufactured by A&D Company, Limited at 23°C, 50% RH, and a tensile speed of 2 mm / min. Elongation at break was determined from the resulting stress-strain curve. The average of five measurements was used as the elongation at break (%) of the polymer layer.

[0360] <Evaluation>

[0361] [Adhesion after long-term storage]

[0362] The glass substrate (slide) and the cover film were bonded together and sealed using an automatic sealing device, Tissuetech Film (manufactured by Sakura Finetech Japan Co., Ltd.) to obtain a sealed body. Xylene was used as the sealing solvent. The slide size was set to 26 mm × 76 mm, and the cover film size was set to 24 mm × 50 mm.

[0363] After storing the sealed bodies at 50°C and 80% RH for 10 days, the seals were visually inspected for peeling of the cover film. The above test was performed on 10 sealed bodies, and the adhesion after long-term storage was evaluated based on the number of seals that peeled, using the following criteria. For practical purposes, a rating of B or higher is preferred.

[0364] A: The number of sealed bodies in which peeling occurred was 0 out of 10.

[0365] B: Peeling occurred in one of ten sealed bodies.

[0366] C: Delamination occurred in 2 or more of 10 sealed bodies.

[0367] Results

[0368] Table 1 shows the configuration of the cover film used in each of the Examples and Comparative Examples, as well as the measurement results and evaluation results.

[0369] In Table 1, the expression "Nk" of the weight average molecular weight represents N×1000, for example, "100k" represents 100,000.

[0370] In Table 1, the numerical values ​​in the polymer composition column represent the mass parts of the repeating units derived from each monomer relative to all the repeating units of the polymer.

[0371] [Table 1]

[0372]

[0373] The results in Table 1 confirm that the cover film of the present invention has excellent adhesion to the glass substrate after long-term storage of a sealed body obtained by laminating the cover film to the glass substrate using a sealing solvent, compared to the cover films of Comparative Examples 1 to 6 that do not satisfy at least one of the following necessary conditions: the polar component δP of the Hansen solubility parameter of the polymer layer is 0.0 to 5.1 MPa 1 / 2 The dissolution rate of the polymer layer in xylene is 0.01-0.25 g·m -2 ·s -1 The viscosity of a xylene solution having a solid content concentration of 20% by mass and obtained by dissolving the polymer layer in xylene at 25°C is 17 to 200 cP; and the elongation at break of the polymer layer is 10% or more.

[0374] From the comparison of Examples 1 and 2, it was confirmed that the polar component δP in the polymer layer was 4.5 MPa. 1 / 2 In the following cases, the effects of the present invention are more excellent.

[0375] Comparison of Examples 1, 3, and 4 confirmed that the effects of the present invention are more excellent when the weight average molecular weight of the polymer is 90,000 to 120,000.

[0376] Comparison of Examples 1 to 4 confirmed that the effect of the present invention is more excellent when the viscosity of a xylene solution having a solid content concentration of 20% by mass obtained by dissolving the polymer layer in xylene is 30 to 75 cP at 25°C.

Claims

1. A covering film comprising a support and a polymer layer comprising a polymer, wherein: The polar component δP of the Hansen solubility parameter of the polymer layer is 0.0 to 5.1 MPa 1 / 2 , The dissolution rate of the polymer layer in xylene is 0.01 to 0.25 g·m -2 ·s -1 , The viscosity of a xylene solution having a solid content concentration of 20% by mass obtained by dissolving the polymer layer in xylene is 17 to 200 cP at 25°C. The elongation at break of the polymer layer is greater than 10%.

2. The covering film according to claim 1, wherein The weight average molecular weight of the polymer is 50,000 to 140,000.

3. The covering film according to claim 1, wherein The polymer comprises at least two repeating units derived from monomers selected from the group consisting of acrylate monomers and methacrylate monomers. The covering film according to claim 1 , wherein: The polymer comprises: Repeating units derived from ethyl acrylate; and at least one repeating unit derived from a monomer selected from the group consisting of methyl methacrylate, ethyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, 2-methoxyethyl methacrylate, n-butyl methacrylate, and 2-ethylhexyl methacrylate, The content of the repeating unit derived from ethyl acrylate is less than 25% by mass relative to all repeating units of the polymer. The covering film according to claim 1 , wherein: The polymer includes repeating units derived from an alkyl methacrylate having an alkyl group having 3 or more carbon atoms. The covering film according to claim 1 , wherein: The thickness of the polymer layer is 5 to 30 μm.

7. The covering film according to claim 1, wherein The weight average molecular weight of the polymer is 90,000 to 120,000.

8. The covering film according to claim 1, wherein The polymer layer further includes at least one compound selected from the group consisting of a silane coupling agent, a hydrolyzate of the silane coupling agent, and a hydrolysis-condensate of the silane coupling agent. 9 . The cover film according to claim 1 , which is used to cover a test object on a substrate.

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