Cover film

Abstract

The present invention addresses the problem of providing a cover film which produces few chips when cut, for which a gap is unlikely to be formed when bonded to a base material with a sealing liquid, and which excels in tight bonding to the base material. This cover film is used to cover a test object placed on a base material. The cover film has: a support; and a polymer layering containing a polymer. The fracture toughness value of the polymer layer is 0.2 MPa·m0.5 or more. The in-plane retardation of the support at a wavelength of 590 nm is 1000 nm or less. Requirements regarding the melting rate of the polymer layer into xylene and requirements regarding the viscosity of a xylene solution of the polymer layer are satisfied.

Description

[Technical Field]

[0001] This invention relates to a cover film. [Background technology]

[0002] A method is known in which a cover film having a polymer layer on a support is automatically superimposed on a substrate (such as a glass slide) on which a few drops of a solvent capable of swelling and / or dissolving the polymer layer (also called a "mounting solution," for example, xylene) have been dropped, and on which the subject to be examined is placed, using an automated mounting device, thereby bonding the cover film and the substrate together (hereinafter also referred to as "mounting"). By this method, a specimen for microscopic observation can be prepared in which the subject to be examined is fixed between the substrate and the cover film.

[0003] For example, Patent Document 1 discloses a microscope cover film comprising a polymer adhesive layer having a glass transition temperature of 50°C or higher on a transparent support, characterized in that a silane coupling agent is contained on the surface of the polymer adhesive layer and / or in the polymer adhesive layer. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-101943 [Overview of the project] [Problems that the invention aims to solve]

[0005] In the above-mentioned automatic sealing device, the cover film is often cut before use, therefore, it is required that no scraps are generated when the cover film is cut. Furthermore, when a cover film is attached to the substrate on which the specimen is placed using a mounting solution, it is also required that gaps are minimized for better observation. Furthermore, in terms of handling and other factors, the cover film is also required to have excellent adhesion to the substrate after sealing.

[0006] When the present inventors examined the cover film described in Patent Document 1, they found that it could not satisfy the above requirements. In particular, the cover film described in Patent Document 1 had voids.

[0007] Therefore, the present invention aims to provide a cover film that generates less chipping when cut, and furthermore, generates less voids when bonded to a substrate using an sealing liquid, and exhibits excellent adhesion to the substrate. [Means for solving the problem]

[0008] The inventors of this invention have diligently studied and developed the present invention to solve the above problems. Specifically, they have found that the above problems can be solved by the following configuration.

[0009] [1] A cover film used to cover a specimen on a substrate, The above cover film has a support and a polymer layer containing a polymer. The fracture toughness value of the above polymer layer is 0.2 MPa·m 0.5 That's all. The in-plane retardation of the above support at a wavelength of 590 nm is 1000 nm or less. A cover film that meets requirements 1 and 2. Requirement 1: The dissolution rate of the above polymer layer in xylene is 0.01 to 0.25 g·m³. -2 ·s -1 That is the case. Requirement 2: When the viscosity of a xylene solution with a solid content of 20% obtained by dissolving the above polymer layer in xylene is X at 25°C, 1 / X should be between 0.005 and 0.060 cP. -1 That is the case. [2] The dissolution rate in xylene is 0.01 to 0.15 g·m³. -2 ·s -1 Therefore, the above 1 / X is 0.010~0.060 cP-1 The cover film described in [1]. [3] The cover film according to [1] or [2], wherein the weight-average molecular weight of the polymer is 50,000 to 140,000. [4] A cover film according to any one of [1] to [3], wherein the glass transition temperature of the polymer layer is 60°C or higher. [5] The cover film according to any one of [1] to [4], wherein the polymer is a polymer comprising at least two repeating units derived from monomers selected from the group consisting of acrylate monomers and methacrylate monomers. [6] The cover film according to any one of [1] to [5], wherein the polymer is a polymer comprising at least two repeating units derived from monomers selected from the group consisting of methyl methacrylate, ethyl acrylate, ethyl methacrylate, 2-methoxyethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, benzyl acrylate, 2-ethylhexyl methacrylate, and lauryl methacrylate. [7] The cover film according to any one of [1] to [6], wherein the polymer comprises repeating units derived from ethyl acrylate and repeating units derived from ethyl methacrylate. [Effects of the Invention]

[0010] According to the present invention, a cover film can be provided that generates less chipping when cut, and furthermore, generates less voids when bonded to a substrate using an sealing liquid, resulting in excellent adhesion to the substrate. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below. The following description of the constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

[0012] The following definitions are used within this specification. In this specification, a numerical range represented by "~" means a range that includes the numbers before and after "~" as the lower and upper limits. In numerical ranges described stepwise in this specification, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Also, in numerical ranges described in this specification, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the amount of each component in a composition or layer means the total amount of any multiple substances present in the composition, unless otherwise specified, if there are multiple substances corresponding to each component in the composition. In this specification, "(meth)acrylic" is a general term that includes acrylic and methacrylic, and means "at least one of acrylic and methacrylic." Similarly, "(meth)acrylate" means "at least one of acrylate and methacrylate." In this specification, unless otherwise specified, the refractive index refers to the refractive index for light with a wavelength of 550 nm, as measured using an Atago NAR-2T.

[0013] In this specification, the acid dissociation constant (pKa) refers to the pKa in aqueous solution, and specifically, it is a value calculated using the software package 1 described below, based on a database of Hammett substituent constants and known literature values. Software Package 1: Advanced Chemistry Development (ACD / Labs) Software V8.14 for Solaris (1994-2007 ACD / Labs).

[0014] On the other hand, pKa can also be determined by molecular orbital calculations. Specifically, this method involves calculating the H₂ in aqueous solution based on the thermodynamic cycle. +Examples of methods for calculating dissociation free energy include those calculated by calculating dissociation free energy. H + Regarding the calculation method of dissociation free energy, for example, it can be calculated by DFT (density functional theory), but various other methods have been reported in the literature and are not limited to this. There are multiple software that can perform DFT, for example, Gaussian16.

[0015] As described above, the pKa in this specification refers to the value obtained by calculation based on the Hammett substituent constant and the database of known literature values using Software Package 1. However, when the pKa cannot be calculated by this method, the value obtained by Gaussian16 based on DFT (density functional theory) shall be adopted. Also, as described above, the pKa in this specification refers to "pKa in aqueous solution". However, when the pKa in aqueous solution cannot be calculated, "pKa in dimethyl sulfoxide (DMSO) solution" shall be adopted.

[0016] <Cover film> The cover film of the present invention is used to cover the specimen on the substrate. Further, the cover film of the present invention has a support and a polymer layer containing a polymer, and the fracture toughness value of the polymer layer is 0.2 MPa·m 0.5 or more, the in-plane retardation at a wavelength of 590 nm of the support is 1000 nm or less, and the following Requirements 1 and Requirements 2 are satisfied. Requirement 1: The dissolution rate of the polymer layer in xylene is 0.01 to 0.25 g·m -2 ·s -1 is. Requirement 2: When the viscosity at 25 °C of a xylene solution with a solid content concentration of 20% obtained by dissolving the polymer layer in xylene is X, 1 / X is 0.005 to 0.060 cP -1 is.

[0017] The mechanism by which the cover film of the present invention generates less scrap when cut, and furthermore, when bonded to a substrate using an sealing liquid, it generates less void and exhibits excellent adhesion to the substrate is not entirely clear, but the inventors speculate as follows. The fracture toughness value of the cover film of the present invention is 0.2 MPa·m 0.5 As a result of these factors, the film can follow deformations that may occur during cutting without breaking, and it is thought that less chipping will be generated when cutting the cover film. Furthermore, in order to minimize the formation of voids when the cover film and substrate are bonded together using the sealing liquid, and to achieve excellent adhesion with the substrate, it is considered necessary to move the polymer into the voids and to ensure adhesion by the polymer. Here, the above dissolution rate is 0.25 g·m³. -2 ·s -1 The following conditions ensure that the penetration rate of the encapsulating solution into the polymer layer is appropriate, and that sufficient time is available for the polymer to move from the polymer layer into the void. On the other hand, the above dissolution rate is 0.01 g·m³. -2 ·s -1 As a result, a sufficient amount of polymer is supplied between the cover film and the substrate to ensure adhesion before the encapsulating liquid disappears due to drying or other reasons. Furthermore, the above 1 / X is 0.060 cP -1 The following conditions result in excellent polymer diffusion, allowing the polymer to move into the voids. On the other hand, the above 1 / X is 0.005 cP -1 The above conditions indicate that the polymer itself has a predetermined molecular chain length, and by using such a polymer, the cover film and the substrate can be tightly bonded. In other words, by satisfying requirements 1 and 2 above, it is possible to reduce the occurrence of voids when the cover film and substrate are bonded together using the sealing liquid, and to achieve excellent adhesion between the cover film and the substrate.

[0018] The following describes the structure and other aspects of the cover film. The fracture toughness value, requirement 1, and requirement 2 will be described in detail later. In addition, the following terms refer to the low generation of scraps during cutting as "scraping resistance," the low generation of voids when the cover film and substrate are bonded together using the sealing liquid as "void suppression," and the excellent adhesion between the cover film and substrate as "adhesion."

[0019] [Support] As a support for the cover film, a transparent support is preferred in terms of microscopicity. In this specification, "transparent" means that the transmittance of visible light (wavelength: 380-780 nm) is 60% or more. Transmittance is the ratio of transmitted light to incident light through the support.

[0020] (Material of the support) The transparent support is not particularly limited, and any known transparent support can be used. In particular, the transparent support is preferably made of a material in which the content of the specific ester compound described later is 1% by mass or less relative to the total mass of the support. Examples of materials constituting the support include cellulose-based polymers such as cellulose triacetate (TAC), cellulose diacetate, cellulose acetate propionate, and cellulose acetate butyrate; polyester-based polymers such as aliphatic polyesters; polyolefin-based polymers such as cycloolefin polymer (COP), polyethylene, and polypropylene; acrylic resin; polycarbonate (PC); and polystyrene. Cellulose-based polymers, acrylic resins, or cycloolefin polymers (COP) are preferred, and cellulose triacetate (TAC) is more preferred.

[0021] If the material constituting the support is a polymer, its weight-average molecular weight (Mw) is, for example, 10,000 to 1,000,000, and preferably 30,000 to 300,000.

[0022] The support material may consist of one of the above materials alone, or two or more materials. The content of the above material in the support is preferably more than 50% by mass, and more preferably 80% by mass or more, relative to the total mass of the support. The upper limit is not particularly limited; if the support does not contain the specific ester compound, it may be 100% by mass or less relative to the total mass of the support, and if the support contains the specific ester compound, it may be the remainder.

[0023] (Specific ester compounds) The support having the cover film of the present invention preferably contains a specific ester compound in an amount of 1% by mass or less relative to the total mass of the support. In other words, the support preferably does not contain the specific ester compound, or if it does contain the specific ester compound, it is preferable that it contains it in an amount of 1% by mass or less relative to the total mass of the support. A specific ester compound is an ester compound obtained by a condensation reaction between an oxoacid of an organic or inorganic acid and a compound containing a hydroxyl group, wherein the pKa of at least one of the hydrolysates, i.e., the oxoacid of the organic or inorganic acid and the compound containing the hydroxyl group, is 2.5 or less. If multiple pKas exist for the ester compound, it is sufficient if at least one of the pKas is 2.5 or less.

[0024] Examples of specific ester compounds include phosphate ester compounds, phosphite ester compounds, sulfonic acid ester compounds, and nitrate ester compounds. Examples of hydrolyzed products of specific ester compounds with a pKa of 2.5 or less include phosphoric acid produced by the hydrolysis of phosphate ester compounds, phosphorous acid produced by the hydrolysis of phosphite ester compounds, sulfonic acids such as methanesulfonic acid and benzenesulfonic acid produced by the hydrolysis of sulfonic acid ester compounds, and nitric acid produced by the hydrolysis of nitrate ester compounds.

[0025] Examples of phosphate ester compounds include triphenyl phosphate, biphenyldiphenyl phosphate, bisphenol A bis-(diphenyl phosphate), trimethyl phosphate, triethyl phosphate, diphenyl-2-methacryloylethyl phosphate, tricresyl phosphate, trixylenyl phosphate, and cresyldiphenyl phosphate. Examples of phosphite ester compounds include triphenyl phosphite, biphenyldiphenyl phosphite, bisphenol A bis-(diphenyl phosphite), trimethyl phosphite, triethyl phosphite, diphenyl-2-methacryloylethyl phosphite, tricresyl phosphite, trixylenyl phosphite, and cresyldiphenyl phosphite. Examples of sulfonic acid ester compounds include methyl benzenesulfonate, ethyl benzenesulfonate, methyl toluenesulfonate, and ethyl toluenesulfonate. As the specific ester compound, phosphate ester compounds are preferred, triphenyl phosphate, biphenyldiphenyl phosphate, or tricresyl phosphate are more preferred, and triphenyl phosphate or biphenyldiphenyl phosphate are even more preferred.

[0026] If the support contains a specific ester compound, the specific ester compound may be a single compound or two or more compounds. If two or more specific ester compounds are present, it is preferable that the total content of the specific ester compounds is 1% by mass or less relative to the total mass of the support. When the support contains a specific ester compound, the content of the specific ester compound is preferably 0.6% by mass or less, and more preferably 0.4% by mass or less, relative to the total mass of the support. It is particularly preferable that the support does not contain a specific ester compound.

[0027] The content of specific ester compounds in the support can be measured by the following measurement method. For example, the types of ester compounds contained in the support and their respective content are measured using known measurement methods such as gas chromatography-mass spectrometry (GC / MS). The pKa of the hydrolysates produced by the hydrolysis of each ester compound contained in the support is calculated from the structural formula of the ester compounds. If hydrolysates with a pKa of 2.5 or less exist, the content of the ester compound from which the hydrolysates are produced (total content if there are two or more types) is considered the content of the specific ester compound. If no hydrolysates with a pKa of 2.5 or less exist, the support is considered to be free of the specific ester compound.

[0028] (Second ester compound) The support may contain secondary ester compounds other than the specified ester compound. The second ester compound is not particularly limited as long as it is an ester compound in which the pKa of all hydrolyzed products is greater than 2.5, but examples include carboxylic acid esters composed of a carboxylic acid and a hydroxyl group-containing compound. Examples of carboxylic acid ester compounds include sugar ester compounds.

[0029] - Sugar ester compounds - Sugar ester compounds are compounds in which some or all of the hydrogen atoms in the hydroxyl groups of sugars are replaced by acyl groups. Examples of sugars include monosaccharides, disaccharides, and polysaccharides, with disaccharides being preferred. Examples of monosaccharides include pentoses such as ribose, deoxyribose, arabinose, and xylose; hexoses such as glucose, galactose, and fructose; trioses, tetrose, and heptose. Examples of disaccharides include sucrose, lactose, maltose, trehalose, turanose, and cellobiose, with sucrose being preferred. Examples of polysaccharides include glycogen and starch. Saccharides may have either a chain structure or a cyclic structure. Examples of the cyclic structures that saccharides may have include, for example, furanose rings and pyranose rings.

[0030] Examples of the acyl group include aliphatic acyl groups such as formyl group, acetyl group, propionyl group, 2-methylpropionyl group, 2,2-dimethylpropionyl group, and 2-ethylhexanoyl group; and aromatic acyl groups such as benzoyl group, 1-naphthylcarbonyl group, 2-naphthylcarbonyl group, and 2-furylcarbonyl group. The number of carbon atoms of the acyl group is preferably 1 to 10.

[0031] As the sugar ester compound, sugar ester compounds represented by the following general formulas (I) to (III) are also preferable. (I) (HO)m-G-(L-R 1 )n (II) (HO)p-G-(L-R 1 )q (III) (HO)t-G’-(L’-R 2 )r (In general formulas (I) to (III), G and G’ each independently represent a monosaccharide residue or a disaccharide residue. R 1 each independently represents an aliphatic group or an aromatic group, and at least one represents an aromatic group. R 2 each independently represents an aliphatic group. L and L’ each independently represent a divalent linking group. m represents an integer of 0 or more, n, p, and q each independently represent an integer of 1 or more, r represents an integer of 3 or more, and t represents an integer of 0 or more. However, m + n ≧ 4, p + q ≧ 4, m > p, and n < q. Also, m + n and p + q are each equal to the number of hydroxyl groups when assuming that G is an unsubstituted saccharide having a cyclic acetal structure of the same skeleton rather than a residue, and r + t is equal to the number of hydroxyl groups when assuming that G’ is an unsubstituted saccharide having a cyclic acetal structure of the same skeleton rather than a residue.)

[0032] It is more preferable to use a sugar ester compound mixture obtained by mixing an aromatic sugar ester compound represented by the above general formula (I), an ester compound represented by the above general formula (II) with a different degree of substitution from the aromatic sugar ester compound represented by the above general formula (I), and an aliphatic sugar ester compound represented by the above general formula (III) as the sugar ester compound. The following describes the preferred range common to all sugar ester compounds, as well as the preferred range specific to each sugar ester compound that satisfies general formulas (I) to (III).

[0033] Each sugar ester compound used in the above sugar ester compound mixture has a monosaccharide residue or a disaccharide residue as its backbone. That is, in the above general formulas (I) to (III), G and G' each independently represent a monosaccharide residue or a disaccharide residue.

[0034] The sugar ester compounds described above refer to compounds in which at least one of the substitutable groups (e.g., hydroxyl groups, carboxyl groups) in the sugar backbone structure constituting the compound is esterified with at least one substituent. In other words, the sugar ester compounds described herein include sugar derivatives in a broad sense, and also include compounds that contain sugar residues as structural components, such as gluconic acid. That is, the sugar ester compounds described above include esters of glucose and carboxylic acids, as well as esters of gluconic acid and alcohols.

[0035] The above sugar ester compounds preferably have a furanose structure or a pyranose structure. When they have a furanose structure or a pyranose structure as a sugar backbone, the conditions that m+n≧4, p+q≧4, and r is 3 or greater are satisfied in the above general formulas (I) to (III). Furthermore, if the sugar backbone is a furanose or pyranose structure, the following conditions are also met: m+n and p+q are equal to the number of hydroxyl groups if we assume that G is not a residue but an unsubstituted sugar with a cyclic acetal structure of the same backbone; and r+t is equal to the number of hydroxyl groups if we assume that G' is not a residue but an unsubstituted sugar with a cyclic acetal structure of the same backbone. Furthermore, the upper limits for m+n, p+q, and r+t can be determined by the type of G or G', and will be 5 if G or G' is a monosaccharide residue, and 8 if it is a disaccharide residue.

[0036] The sugar ester compounds represented by the above general formulas (I) to (III) are preferably esterified compounds in which all or part of the OH groups are esterified in a compound (A) in which G or G' is a monosaccharide residue having one furanose structure or pyranose structure, or in a compound (B) in which G or G' is a disaccharide residue having at least two furanose structures or pyranose structures linked together.

[0037] Examples of compound (A) include, but are not limited to, glucose, galactose, mannose, fructose, xylose, and arabinose. Compound (B) includes lactose, sucrose, nystose, 1F-fructosylnistose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cerotriose, maltotriose, raffinose, and kestose. Other examples include, but are not limited to, gentiobiose, gentiotriose, gentiotetraose, xylotriose, and galactosylsucrose. Among these compounds (A) and (B), compounds having both a furanose structure and a pyranose structure are particularly preferred. Examples include sucrose, kestose, nystose, 1F-fukratosylnistose, or stachyose, with sucrose being more preferred. In addition, in compound (B), a compound having at least two furanose or pyranose structures bonded together is also a preferred embodiment.

[0038] There are no particular restrictions on the substituents used to esterify all or part of the OH groups in compound (A) and compound (B). Among these, monocarboxylic acids are preferred. That is, the R in the above general formula (I) and the above general formula (II)1 , and the above R in the general formula (III) 2 However, it is preferable that each independently represents an acyl group. The above monocarboxylic acid is not particularly limited, and known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids, etc., can be used. One type of carboxylic acid may be used, or a mixture of two or more types may be used. The above R 1 Or the above R 2 If there are multiple instances, they may be identical or different from one another.

[0039] On the other hand, L in the above general formula (I) and the above general formula (II), and L' in the above general formula (III) are independently single bonds, -O-, -CO-, and -NR, respectively. 11 -(R 11 It is preferable that the above L represents one of the following (where represents a monovalent substituent), and also L 1 Alternatively, if there are multiple L's, they may be the same or different from each other. Among them, L 1 Alternatively, the above L' represents -O-, as indicated by the above R 1 and R 2 It is preferable from the viewpoint that it can be easily substituted with an acyl group.

[0040] Next, preferred embodiments of aromatic sugar ester compounds represented by the above general formulas (I) and (II) will be described. In the above general formulas (I) and (II), the above R 1 Each of these independently represents either an aliphatic group or an aromatic group, and at least one represents an aromatic group. Among these, the above R 1 It is preferable that each of these independently represents only an aromatic group, and it is even more preferable that they all represent the same aromatic group.

[0041] Furthermore, in the general formulas (I) and (II) above, m represents an integer greater than or equal to 0, n, p, and q each independently represent an integer greater than or equal to 1, m > p, and n <qである。 In the aromatic sugar ester compounds represented by the above general formula (I) and the aromatic sugar ester compounds represented by the above general formula (II), when G is a disaccharide residue, n is preferably 3 or more, and more preferably 5 or more.

[0042] R 1 Examples of preferred aromatic monocarboxylic acids used when substituted include aromatic monocarboxylic acids obtained by introducing an alkyl group or alkoxy group to the benzene ring of benzoic acid, such as benzoic acid and toluic acid; cinnamic acid; aromatic monocarboxylic acids having two or more benzene rings, such as benzyl acid, biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralinecarboxylic acid; and derivatives thereof.

[0043] Next, preferred embodiments of the aliphatic sugar ester compound represented by the above general formula (III) will be described. In the above general formula (III), the above R 2 Each of these independently represents an aliphatic group.

[0044] R 2 Preferred aliphatic monocarboxylic acids used when substituted by include saturated fatty acids such as acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, heptacosanic acid, montanic acid, melissic acid, and laxeric acid; and unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, and octenic acid. Preferred examples of alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, and cyclooctanecarboxylic acid, as well as their derivatives.

[0045] The above R 2 Preferably, each of them independently represents an acyclic aliphatic group, and all R 2It is preferable that this represents an acyclic aliphatic group. The above R 2 It is preferable that this represents two or more aliphatic groups. Among aliphatic monocarboxylic acids, the aliphatic sugar ester compound represented by the above general formula (III) is preferably substituted with at least acetic acid. That is, the above R in the above general formula (III) 2 It is preferable that at least one of them represents an acetyl group. On the other hand, the above R 2 It is more preferable that at least one of them represents a branched aliphatic group, and the above R 2 When R represents two or more aliphatic groups, it is particularly preferable that only one of them represents a branched aliphatic group. Among these, it is preferable that the aliphatic sugar ester compound represented by the above general formula (III) is substituted with isobutyric acid in addition to acetic acid. That is, the above R in the above general formula (III) 2 It is preferable that it contains an acetyl group and an isobutyryl group.

[0046] In the above general formula (III), it is preferable that G' represents a disaccharide residue from the viewpoint of improving the planar failure of the resulting cellulose ester film.

[0047] A method for producing these aliphatic sugar ester compounds substituted with aliphatic monocarboxylic acids is described, for example, in Japanese Patent Publication No. 8-245678.

[0048] When using a combination of sugar ester compounds represented by the above general formulas (I) to (III) as the sugar ester compound, the mixing ratio is not particularly limited, but it is preferable that the total content of aromatic sugar ester compounds / content of aliphatic ester compounds (mass ratio) is greater than 1, more preferably 2 to 10, and even more preferably 3 to 5. Furthermore, when using a combination of sugar ester compounds represented by the above general formulas (I) to (III) as the sugar ester compound, the total content of the sugar ester compounds represented by the above general formulas (I) to (III) is preferably 1 to 30% by mass, more preferably 5 to 30% by mass, even more preferably 5 to 20% by mass, and particularly preferably 5 to 15% by mass, relative to the cellulose ester.

[0049] For sugar ester compounds represented by the above general formulas (I) to (III), refer also to paragraphs

[0015] to

[0056] of Japanese Patent Application Publication No. 2012-031313, which are incorporated herein by reference.

[0050] (Properties of the support) - thickness - The thickness of the support is not particularly limited, but is preferably 50 to 250 μm, more preferably 50 to 150 μm, and even more preferably 100 to 150 μm.

[0051] -Refractive index- The refractive index of the support is not particularly limited, but may be, for example, 1.440 to 1.600. From the viewpoint of microscopicity, 1.460 to 1.560, which is close to that of a microscope slide (refractive index 1.52 to 1.56), is preferred.

[0052] -Lettering- The in-plane retardation of the support is less than 1000 nm. The in-plane retardation of the support is preferably 600 nm or less, more preferably 400 nm, and even more preferably 200 nm or less, from the standpoint of suitability for polarized light microscopy observation. The lower limit of the in-plane retardation is 0 nm. The retardation of the support in the thickness direction is preferably -300 to 300 nm, more preferably -100 to 100 nm, and even more preferably -50 to 50 nm, from the standpoint of suitability for observation with a polarizing microscope. In this specification, the in-plane retardation Re(λ) at wavelength λ and the thickness-direction retardation Rth(λ) at wavelength λ refer to those measured by the following method. Unless otherwise specified, λ is assumed to be 590 nm. Re(λ) and Rth(λ) can be calculated from 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 Instruments Co., Ltd.).

[0053] The surface of the support may be provided with an undercoat layer, which is well known in the photographic photosensitive materials industry. The support may also be subjected to surface treatments such as ultraviolet irradiation, corona discharge, or glow discharge.

[0054] [Polymer layer] The polymer layer of the cover film contains polymer and has a fracture toughness value of 0.2 MPa·m 0.5 Therefore, requirements 1 and 2 are met. The following describes the polymers and optional components contained in the polymer layer, followed by a description of the requirements that the polymer layer must meet.

[0055] (polymer) The polymer contained in the polymer layer has a fracture toughness value of 0.2 MPa·m. 0.5 The above is all; there are no particular restrictions as long as requirements 1 and 2 are met. The polymer contained in the polymer layer is preferably swollen with an organic solvent used as a sealing liquid in an automatic sealing device, and more preferably dissolved in the above organic solvent. Examples of organic solvents used in the automatic sealing device include xylene, toluene, mesitylene (1,3,5-trimethylbenzene), pseudocumene (1,2,4-trimethylbenzene), hemimelitene (1,2,3-trimethylbenzene), durene (1,2,4,5-tetramethylbenzene), anisole, ethyl propionate, amyl acetate, propyl acetate, isopropyl acetate, methyl butyl lactate acetate, dimethyl carbonate, 1-butanol, 1-propanol, 2-butanol, 1-pentanol, 2-pentanol, isoamyl Examples of solvents include any single solvent from among ethanol, t-amyl alcohol, 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, 2-methoxy-1-methyl ethyl acetate, ethyl acetate, methyl acetate, acetone, and methyl ethyl ketone, as well as mixtures of two or more of these. The polymer swells in the above organic solvent or dissolves in the above organic solvent, causing the cover film and substrate to adhere and the specimen to be sealed.

[0056] As the polymer, acrylic resin is preferred due to its excellent solubility in the above-mentioned organic solvents. In this specification, acrylic resin means a polymer having repeating units derived from acrylate monomers and / or methacrylate monomers. The acrylic resin is not particularly limited as long as it has repeating units derived from acrylate monomers and / or methacrylate monomers. It may be a homopolymer containing repeating units derived from one monomer selected from the group consisting of acrylate monomers and methacrylate monomers, or it may be a polymer (polymer) containing at least two types of repeating units derived from monomers selected from the group consisting of acrylate monomers and methacrylate monomers. Furthermore, the acrylic resin may be a copolymer comprising repeating units derived from at least one monomer selected from the group consisting of acrylate monomers and methacrylate monomers, and at least one monomer other than acrylate monomers and methacrylate monomers (for example, acrylamide monomers such as dimethylacrylamide and isopropylacrylamide, and vinyl monomers such as styrene). In acrylic resins, the content of repeating units derived from acrylate monomers and / or methacrylate monomers is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, relative to the total repeating units of the acrylic resin. There is no particular upper limit to the content of repeating units derived from acrylate monomers and / or methacrylate monomers, and it may be 100% by mass relative to the total repeating units of the acrylic resin. The acrylic resin is particularly preferably one that has only repeating units derived from acrylate monomers and / or methacrylate monomers. Acrylic resins can be prepared by known methods, for example, by polymerizing at least one monomer selected from the group consisting of acrylate monomers and methacrylate monomers.

[0057] Examples of the acrylate monomer and methacrylate monomer mentioned above include alkyl acrylates and alkyl methacrylates. The alkyl group in alkyl acrylates and alkyl methacrylates may be linear or branched. Furthermore, the alkyl group may have further substituents. Examples of substituents include aryl groups and hydroxyl groups, with aryl groups being preferred and phenyl groups being more preferred. The number of carbon atoms of the alkyl group that may have substituents in the alkyl acrylate and alkyl methacrylate is preferably 1 to 15, more preferably 1 to 8, even more preferably 1 to 5, and particularly preferably 1 to 3. Some of the methylene groups constituting the alkyl group may be replaced by divalent substituents. Examples of these divalent substituents include -O- and -CO-. Specific examples of the above acrylate monomers include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, lauryl acrylate, phenyl acrylate, benzyl acrylate, 2-methoxyethyl methacrylate, hydroxyethyl acrylate, and acetoacetoxyalkyl acrylate. Specific examples of the above methacrylate monomers include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, lauryl methacrylate, 2-methoxyethyl methacrylate, hydroxyethyl methacrylate, and 2-acetoacetoxyethyl methacrylate.

[0058] In particular, the polymer preferably contains repeating units derived from at least one monomer selected from the group consisting of ethyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, lauryl methacrylate, 2-methoxyethyl methacrylate, 2-acetoacetoxyethyl methacrylate, phenyl acrylate, phenyl methacrylate, styrene, and dimethylacrylamide, and more preferably contains repeating units derived from at least one monomer selected from the group consisting of ethyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, benzyl methacrylate, lauryl methacrylate, and 2-methoxyethyl methacrylate.

[0059] One preferred embodiment of the polymer constituting the polymer layer is a polymer X containing repeating units derived from alkyl acrylate and repeating units derived from alkyl methacrylate. The repeating units derived from alkyl acrylates contained in polymer X are preferably alkyl acrylates having an alkyl group with 1 to 7 carbon atoms (preferably 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms), and repeating units derived from ethyl acrylate are more preferred from the viewpoint of fracture toughness. In polymer X, the content of repeating units derived from alkyl acrylate is preferably 5 to 40% by mass, and more preferably 20 to 30% by mass, relative to the total repeating units of polymer X.

[0060] The repeating units derived from alkyl methacrylate contained in polymer X are preferably repeating units derived from alkyl methacrylate having an alkyl group with 1 to 15 carbon atoms (preferably 1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms). Examples of alkyl methacrylates that constitute the repeating units derived from alkyl methacrylates include methyl methacrylate, ethyl methacrylate, 2-methoxyethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, benzyl acrylate, 2-ethylhexyl methacrylate, and lauryl methacrylate. Among these, polymer X is preferably composed of repeating units derived from ethyl methacrylate, t-butyl methacrylate, or benzyl acrylate, and more preferably composed of repeating units derived from ethyl methacrylate, from the viewpoint of dissolution rate and fracture toughness. In polymer X, there may be only one repeating unit derived from alkyl methacrylate, or there may be two or more. In polymer X, the content of repeating units derived from alkyl methacrylate is preferably 60 to 95% by mass, and more preferably 70 to 90% by mass, relative to the total repeating units of polymer X.

[0061] A preferred embodiment of polymer X is polymer Y, which contains repeating units derived from ethyl acrylate, repeating units derived from methyl methacrylate, and repeating units derived from other alkyl methacrylates other than methyl methacrylate. As mentioned above, ethyl methacrylate is an example of the other alkyl methacrylate. In polymer Y, the content of repeating units derived from ethyl acrylate is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass, relative to the total repeating units of polymer Y. In polymer Y, the content of repeating units derived from methyl methacrylate is preferably 20 to 80% by mass, and more preferably 50 to 70% by mass, relative to the total repeating units of polymer Y. Furthermore, the content of repeating units derived from other alkyl methacrylates (preferably ethyl methacrylate) other than methyl methacrylate in polymer Y is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, and even more preferably 15 to 25% by mass, relative to the total repeating units of polymer Y.

[0062] The weight-average molecular weight (Mw) of the polymer is preferably 10,000 to 500,000, more preferably 50,000 to 140,000, and even more preferably 80,000 to 120,000. In this specification, unless otherwise specified, the weight-average molecular weight (Mw) is the molecular weight obtained by gel permeation chromatography (GPC) analysis using TSKgel GMHxL, TSKgel G4000HxL, TSKgel G2000HxL, and / or TSKgel Super HZM-N (all trade names of Tosoh Corporation) columns, using THF (tetrahydrofuran) as the solvent, detected by differential refractometer, and converted using polystyrene as the standard substance.

[0063] When the cover film of the present invention is used as a cover film for stained specimens, the observationability may decrease due to the spread of the staining dye within the polymer layer. To prevent this, it is preferable to reduce the compatibility between the polymer and the staining dye. The compatibility between a polymer and a dye (e.g., eosin) can be determined from the Hansen solubility parameter distance. For example, the Hansen solubility parameter distance between the polymer and the dye is 12.00 MPa. 0.5 The above is preferable, and 12.50 MPa 0.5 The above is more preferable, 13.00 MPa 0.5 The above is even more preferable. There is no upper limit to the Hansen solubility parameter distance; for example, the Hansen solubility parameter distance is 40.00 MPa. 0.5 The following applies:

[0064] The polymer content in the polymer layer is not particularly limited, but is preferably 85% by mass or more, and more preferably 90% by mass or more, relative to the total mass of the polymer layer. The upper limit may be 100% by mass or less, preferably 99.99% by mass or less, and more preferably 99.95% by mass or less. The polymer may be used alone or in combination of two or more types. When using two or more polymers, it is preferable that they be used in a ratio that does not cause turbidity in the dried film formed by the mixture of the two or more polymers.

[0065] (Silane coupling agents) The polymer layer may contain at least one selected from the group consisting of silane coupling agents, their hydrolysates, and their hydrolyzed condensates (hereinafter, these are collectively referred to as "silane coupling agents"). When the polymer layer contains silane coupling agents, it is preferable that blocking is less likely to occur 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) even when the cover film of the present invention is stored in a roll, and that it has better storage properties over time.

[0066] The type of silane coupling agent is not particularly limited, but a silane coupling agent having two or more different reactive groups in its molecule is preferred, wherein at least one of the reactive groups chemically bonds with an inorganic material and at least one of the reactive groups chemically bonds with an organic material.

[0067] Examples of silane coupling agents include those represented by the following general formula. X-Si(R 1 )3 X represents a group that has a reactive group. Examples of reactive groups include vinyl groups, epoxy groups, amino groups, (meth)acrylic groups, and mercapto groups. More specifically, X can be R 2 It can be represented as a group -L-. 2represents a reactive group, and L represents a divalent linking group (preferably an alkylene group which may contain a heteroatom (e.g., an oxygen atom)). R 1 The symbol represents a hydrolyzable group. A hydrolyzable group is a group that is directly bonded to a Si (silicon atom) and can undergo hydrolysis and / or condensation reactions. Examples of hydrolyzable groups include alkoxy groups, halogen atoms, acyloxy groups, alkenyloxy groups, and isocyanate groups.

[0068] Silane coupling agents include, for example, vinyltrichlorosilane, vinyltris(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 One or more selected from the group consisting of toxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane is preferred, one or more selected from the group consisting of γ-glycidoxypropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane is more preferred, one or more selected from the group consisting of γ-glycidoxypropyltrimethoxysilane and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane is even more preferred, and γ-glycidoxypropyltrimethoxysilane is particularly preferred.

[0069] The term "hydrolyzed silane coupling agent" refers to a compound obtained by hydrolyzing the hydrolyzable groups in the silane coupling agent. The hydrolyzed product may be a complete hydrolyzed product (where all hydrolyzable groups have been hydrolyzed) or a partial hydrolyzed product (where only some hydrolyzable groups have been hydrolyzed). In other words, the hydrolyzed product may be a complete hydrolyzed product, a partial hydrolyzed product, or a mixture thereof. Furthermore, the term "hydrolysis condensate of a silane coupling agent" refers to a compound obtained by hydrolyzing the hydrolyzable groups in the silane coupling agent and condensing the resulting hydrolysates. The hydrolysis condensate may be a compound in which all hydrolyzable groups are hydrolyzed and all hydrolysates are condensed (a complete hydrolysis condensate), or a compound in which some hydrolyzable groups are hydrolyzed and some hydrolysates are condensed (a partial hydrolysis condensate). In other words, the hydrolysis condensate may be a complete hydrolysis condensate, a partial hydrolysis condensate, or a mixture thereof.

[0070] It will be readily understood by those skilled in the art that the type of silane coupling agent used in the polymer layer is selected according to the type of organic material to be bonded to the glass, i.e., the type of polymer constituting the polymer layer.

[0071] The content of silane coupling agents in the polymer layer is 0.1 mg / m² relative to the area of ​​the polymer layer. 2 The above is preferable, with a dose of 5-25 mg / m². 2 This is preferable. Silane coupling agents may be used individually or in combination of two or more types.

[0072] The silane coupling agents in the polymer layer may be uniformly distributed throughout the polymer layer, or they may be unevenly distributed on any surface of the polymer layer. If the silane coupling agents are unevenly distributed on any surface of the polymer layer, that surface may be the surface of the polymer layer facing the support, or the surface of the polymer layer on the opposite side of the support.

[0073] (Plasticizer) The polymer layer of the present invention may contain a plasticizer. By including a plasticizer, the compatibility of the polymer layer with the solvent (such as xylene) is improved, increasing the dissolution rate when the polymer layer comes into contact with the solvent, and improving the brittleness of the polymer layer. The type of plasticizer is not particularly limited, but a plasticizer with high compatibility with the polymer used is preferred. For example, a small Hansen solubility parameter distance between the plasticizer and the polymer is preferred.

[0074] Preferably, the plasticizer is selected from the group consisting of phosphates such as triphenyl phosphate, bisphenol A bis-(diphenyl phosphate), trimethyl phosphate, triethyl phosphate, and diphenyl-2-methacryloylethyl phosphate; dioctyl adipate, dibutyl adipate, and diisobutyl adipate, as well as adipate esters such as ADEKA LV-808 (manufactured by ADEKA Corporation), and Polysizer W-242, W-230-H, W-1020-EL, and W-1430-EL; sebacate esters such as dioctyl sebacate; tris(2-ethylhexyl) trimellitate; dibutyl maleate; and glycerin triacetate.

[0075] In addition, preferred plasticizers include phthalate esters such as diisononyl phthalate, bis(2-ethylhexyl) phthalate, and isodecyl phthalate; trimetate esters such as Adekasizer C series (e.g., C-8, manufactured by ADEKA) and Monosizer W-705 (manufactured by DIC); pyromellitic acid esters such as Adekasizer UL-80 and UL-100 (manufactured by ADEKA); dipentaerythritol esters such as Adekasizer UL-8 (manufactured by ADEKA); carboxylic acid esters having epoxy groups such as Monosizer W-150 (manufactured by DIC); and benzoic acid esters such as Monosizer PB-3A (manufactured by DIC). Furthermore, glycol compounds such as polyethylene glycol, triethylene glycol bis(2-ethylhexanoate), and diethylene glycol dibenzoate are also preferred as plasticizers.

[0076] Furthermore, the plasticizer may be a deep eutectic solvent (DES). A deep eutectic solvent is a solvent containing a hydrogen bond acceptor compound and a hydrogen bond donor compound. By mixing the hydrogen bond acceptor compound and the hydrogen bond donor compound, eutectic melting point depression occurs, resulting in a solvent with a significantly lowered melting point. Examples of hydrogen bond acceptor compounds include quaternary ammonium compounds, phosphorus compounds, metal salts, amino acids, and polycarboxylic acids, while examples of hydrogen bond donor compounds include alcohol compounds, sugars, carboxylic acids, and amine compounds. Examples of deep eutectic solvents include paragraphs 0025 to 0048 of US2018 / 0194913 and Japanese Patent Publication No. 2020-105336.

[0077] (Thickening agent) The polymer layer may contain a thickening agent. The type of thickener is not particularly limited, but examples include polysaccharides, celluloses, polymer compounds such as acrylics, polyvinyl alcohol, diols and terpenes, inorganic particles such as silica particles and titania particles, and organic particles made of polymers such as PMMA, with cellulose acetate (more preferably cellulose acetate butyrate or cellulose acetate phthalate) or silica particles being preferred.

[0078] It is preferable that the surface of the inorganic particles be hydrophobic, as this can suppress the leaching (migration) of hydrophilic materials from the components in contact with the polymer layer. While there are no particular restrictions on the size of inorganic and organic particles, if they are too large, scattering is likely to occur, which can worsen microscopic observation. Therefore, the average secondary particle diameter of inorganic and organic particles (the average particle diameter of aggregates of inorganic and organic particles) is preferably 1 μm or less. There are no particular restrictions on the lower limit, and it may be 1 nm or more. The average secondary particle diameter of inorganic and organic particles can be measured using a particle size analyzer (nanoSAQLA, manufactured by Otsuka Electronics Co., Ltd.) based on dynamic light scattering. Furthermore, in order to prevent scattering, it is preferable that the refractive index of the inorganic and organic particles be close to the refractive index of the polymer layer. More specifically, it is preferable that the refractive index of the inorganic and organic particles be 1.40 to 1.60.

[0079] If the polymer layer contains the above-mentioned thickeners and / or plasticizers, the respective contents are not particularly limited, but from the viewpoint of better exerting the effect of each additive, it is preferable that the content be 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more, relative to the total mass of the polymer layer. In particular, from the viewpoint of better suppressing chips during cutting, it is especially preferable that the content of the thickener selected from the group consisting of the above-mentioned inorganic particles and organic particles contained in the polymer layer be within the above range. There is no particular upper limit to the content of the above additives, but from the viewpoint of adhesion of the polymer layer, it is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, relative to the total mass of the polymer.

[0080] (Properties of the polymer layer) -Fracture Toughness Value- The fracture toughness value of the polymer layer is 0.2 MPa·m 0.5 That's all. In terms of scrap resistance, the fracture toughness value of the polymer layer is 1.0 MPa·m 0.5 The above is even more preferable. There is no particular upper limit to the fracture toughness value of the polymer layer, but 5.0 MPa·m is preferable. 0.5 The following are common cases. The method for measuring the fracture toughness of the polymer layer is as follows: The fracture toughness of the polymer layer is measured by the indentation method (IF method). More specifically, a cube corner indenter (iNano, G200, manufactured by Toyo Technica Co., Ltd.) is pressed into the polymer layer with a load of 20 mN using a nanoindenter, and the fracture toughness (K) is calculated from the length of the crack generated at the corner of the indentation using the following formula. IC Unit: MPa·m 0.5 Calculate ). K IC =α(E / H) 0.5 ·( PC 1.5 ) In the above formula, α is a constant of 0.032, E represents Young's modulus, H represents Vickers hardness, P represents indentation load, and C represents crack length.

[0081] The fracture toughness of the polymer layer can be controlled by adjusting the type of repeating units in the polymer contained within the polymer layer, as well as the weight-average molecular weight.

[0082] -Requirement 1- Requirement 1 regarding the above polymer layer is as follows: Requirement 1: The dissolution rate of the polymer layer in xylene should be 0.01-0.25 g·m³. -2 ·s -1 That is the case. The above dissolution rate (g·m) -2 ·s -1 ) is measured using the following procedure. A cover film having a support and a polymer layer containing a polymer is cut to a predetermined size (24 mm long x 120 mm wide) to obtain a sample for measurement, and its mass (mass before immersion) is measured. The sample for measurement is immersed in xylene (1200 mL) in a container for a certain period of time. After immersion, the cover film is carefully removed from the container and the xylene is thoroughly dried. The mass after drying (mass after immersion) is measured, and the difference between the mass before immersion and the mass after immersion is calculated. The mass difference is measured over the area (m²) of the sample for measurement. 2 The dissolution rate (g·m) can be calculated by dividing the dissolution rate by the immersion time (s) and the dissolution rate (g·m). -2 ·s -1 Calculate ). The immersion time should be set appropriately to allow time for the polymer layer not to dissolve completely, but 30 to 300 seconds is preferred, for example, 60 seconds. The temperature and time for drying the xylene should be set appropriately, for example, 150°C for 60 minutes.

[0083] The above dissolution rates are superior in terms of void suppression and adhesion, with values ​​ranging from 0.03 to 0.25 g·m². -2 ·s -1 Preferably, 0.05-0.20 g·m -2 ·s -1 More preferably, 0.05~0.15g·m -2 ·s -1 That is even more preferable.

[0084] The dissolution rate of the polymer layer can be controlled by adjusting the type of repeating units in the polymer contained within the polymer layer, as well as the weight-average molecular weight.

[0085] -Requirement 2- Requirement 2 regarding the above polymer layer is as follows: Requirement 2: When the viscosity of a xylene solution with a solid content of 20% obtained by dissolving the polymer layer in xylene is X at 25°C, 1 / X should be between 0.005 and 0.060 cP. -1 That is the case. The above 1 / X(cP -1 ) is measured using the following procedure. The polymer layer is peeled off from a cover film having a support and a polymer layer containing the polymer, and the mass of the obtained polymer layer is measured. The obtained polymer layer is dissolved in xylene to prepare a xylene solution with a solid content concentration of 20%. In other words, the xylene solution contains a predetermined amount of the components constituting the polymer layer as solid content. The viscosity X(cP) of the above xylene solution is measured using an E-type viscometer (VISCOMETER RE-85L, manufactured by Toki Sangyo Co., Ltd.). The measurement temperature is 25°C. Take the reciprocal of the measured viscosity X(cP) and calculate 1 / X(cP). -1 Calculate ).

[0086] The above 1 / X(cP -1) is superior in terms of void suppression and adhesion, with a density of 0.007~0.060 cP -1 Preferably, 0.010~0.060 cP -1 More preferably, 0.015~0.050 cP -1 That is even more preferable.

[0087] The above 1 / X(cP -1 This can be controlled by adjusting the type of repeating units in the polymer contained in the polymer layer, as well as the weight-average molecular weight.

[0088] -Glass transition temperature- The glass transition temperature of the polymer layer is not particularly limited, but is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher. The upper limit is not particularly limited, but is 100°C, preferably 90°C or lower, and more preferably 80°C or lower. The glass transition temperature of the polymer layer can be obtained by peeling the polymer layer from the cover film and heating the polymer layer from -50°C to 100°C at a rate of 10°C / min using a differential scanning calorimetry (DSC). The glass transition temperature can be controlled, for example, by the type and amount of repeating units contained in the polymer.

[0089] - thickness - The thickness of the polymer layer is not particularly limited, but is preferably 1 to 100 μm, more preferably 10 to 40 μm, and even more preferably 10 to 30 μm.

[0090] -Refractive index- From an optical standpoint when observed under a microscope, the refractive index of the polymer layer is preferably 1.45 to 1.56, 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.

[0091] [Other layers] The cover film may have layers other than the support and polymer layer. Other layers include the backing layer. The backing layer may be provided on the back surface of the support (the side opposite to the side on which the polymer layer is provided) for purposes such as preventing scratches on the surface of the cover film, more reliably preventing blocking when stored in a very high-temperature environment, or balancing the curling of the cover film. Examples of materials that make up the backing layer include synthetic polymers with high glass transition temperatures such as polystyrene and polymethyl methacrylate, as well as gelatin.

[0092] The total film thickness of the polymer layer and 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 viewpoint of operability and microscopic quality when observed under a microscope. As for the lower limit, it is preferably 50 μm or more from the viewpoint of handling properties such as resistance to breakage and sealing properties.

[0093] <Method for manufacturing cover film> The method for forming the polymer layer on the support is not particularly limited and includes coating by a coater or spray, casting, and transfer. In particular, it is preferable to apply a coating solution, which is obtained by dissolving the polymer in a solvent, onto the support, and then dry the coating film to form the polymer layer.

[0094] The solvent used in the coating solution is preferably one that can dissolve the polymer and has wettability that prevents repulsion on the support. Examples of such solvents include toluene, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, and xylene. By using a solvent that can dissolve the surface of the support, or a material that can elute low molecular weight components such as plasticizers contained in the support, as the solvent for the coating solution, the polymer can penetrate the surface layer of the support, increasing the adhesion between the polymer layer and the support, preventing the peeling of the polymer layer, and further suppressing the generation of chips during cutting. From the above perspective, the coating solution used to form the polymer layer preferably contains a solvent selected from the group consisting of ethyl acetate and butyl acetate, and more preferably contains ethyl acetate. The content of the solvent selected from the group consisting of ethyl acetate and butyl acetate in the coating solution is not particularly limited, but it is preferably 40% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, relative to the total mass of the solvent in the coating solution, in order to further suppress the generation of chips when the cover film is cut. There is no particular upper limit, and it may be 100% by mass or less, but it is preferably 90% by mass or less in order to further suppress the deformation of the substrate.

[0095] It is preferable to apply a coating solution containing the above polymer onto a support to form a coating film, and then perform a drying step to dry the resulting coating film and remove the solvent from the coating film. Drying treatments performed in the drying process include leaving the coating film at room temperature (23°C) for a predetermined time (for example, natural drying), blown-air drying by spraying gas onto the coating film, and heat drying by heating the coating film using a heating means such as an oven, as well as combinations thereof. In the drying process, it is preferable to perform at least one of blown-air drying and heat drying, and it is more preferable to perform a combination of blown-air drying and heat drying.

[0096] The temperature of the gas used for forced-air drying is not particularly limited, but is preferably 50 to 160°C, and more preferably 80 to 140°C. The airflow velocity (wind speed) in forced-air drying is not particularly limited, but is preferably 3 to 15 m / s, and more preferably 5 to 10 m / s. The processing time for forced-air drying is preferably 0.5 to 5 minutes. Examples of gases used for forced-air drying include air and nitrogen. The heating and drying temperature is not particularly limited, but 50 to 160°C is preferred. The heating time is preferably 0.5 to 5 minutes.

[0097] The method for forming a polymer layer containing silane coupling agents is not particularly limited, but examples include: a first method in which silane coupling agents are added in advance to a coating solution for forming a polymer layer, the coating solution containing the polymer and silane coupling agents is applied to a support, and the coating film is dried to form a polymer layer; a second method in which a coating solution obtained by dissolving silane coupling agents 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 solution containing a polymer and a coating solution obtained by dissolving silane coupling agents in a solvent are applied simultaneously (over-coating) to a support, and the coating film is dried to form a polymer layer. In the first to third methods described above, if a silane coupling agent is used as a raw material, the hydrolysis and condensation reactions of the silane coupling agent may proceed during the formation process. The second and third methods described above are preferred because they allow for the effective use of small amounts of silane coupling agents. In polymer layers containing silane coupling agents formed by the second and third methods described above, the silane coupling agents tend to be unevenly distributed on the surface of the polymer layer opposite to the support.

[0098] The solvent used in the second and third methods described above to obtain the coating solution obtained by dissolving silane coupling agents in the solvent is not particularly limited as long as it can dissolve the silane coupling agents, and examples include the solvents listed above that can dissolve the polymers. Among these, ethyl acetate is preferred because it is superior in terms of improving adhesion.

[0099] <Application> The cover film of the present invention can be used as a cover film for covering a specimen on a substrate. In particular, it can be preferably used for preparing specimens for microscopic observation, and is more preferably applied with a microscope equipped with an automated mounting device. The substrate to which the cover film is laminated may be glass or a film-shaped material (such as resin). [Examples]

[0100] The present invention will be described in more detail below based on examples. The materials, quantities, proportions, processing details, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples.

[0101] <Cover film preparation> The cover film was prepared by applying a polymer-containing coating solution to a support. The detailed procedure is described below.

[0102] [Fabrication of support 1] Support material 1 was prepared according to the following method.

[0103] (Preparation of cellulose acylate dope in the core layer) The following components were added to a mixing tank, and the mixture was stirred to dissolve each component, thereby preparing cellulose acetate solution A2a, which was to be used as a cellulose acylate dope for the core layer. • 100 parts by mass of cellulose acetate with an acetyl substitution degree of 2.88 A mixture containing an aliphatic carboxylic acid ester oligomer (oligomer A1) described later and a compound represented by the following formula (A-3), wherein the mass ratio of the content of oligomer A1 to the content of the compound represented by formula (A-3) is 4:1. • Methylene chloride 430 parts by mass • Methanol 64 parts by mass The amount of the above mixture added to cellulose ester solution A2a was adjusted so that the total content of polyester A and the compound represented by formula (A-3) in support 1, which is prepared using cellulose ester solution A2a and cellulose ester solution A2b described later, by the method described below, is 12.3%.

[0104] [ka]

[0105] Oligomer A1 is an aliphatic carboxylic acid ester oligomer, a condensate of 1,2-cyclohexyldicarboxylic acid and ethylene glycol, and has a terminal structure in which the hydrogen atoms of the hydroxyl groups at both ends are substituted (sealed) by cyclohexanoyl groups. The number-average molecular weight of oligomer A1 was 850.

[0106] (Preparation of outer layer cellulose acylate dope) To prepare cellulose acetate solution A2b for use as the outer layer cellulose acylate dope, cellulose acetate solution A2b was prepared by adding 10 parts by mass of mat agent solution B2 having the following composition to 90 parts by mass of the above cellulose acetate solution A2a (core layer cellulose acylate dope).

[0107] -Composition of Mat Solution B2- • 2 parts by mass of silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) • Methylene chloride 76 parts by mass • 11 parts by mass of methanol • Cellulose acetate solution A2a (core layer cellulose acylate doped) 1 part by mass

[0108] (Fabrication of support 1) The core layer cellulose acylate dope and the outer layer cellulose acylate dope were filtered using filter paper with an average pore size of 34 μm and a sintered metal filter with 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 in three layers from the casting port of a band casting machine onto the surface of a drum with a surface temperature of 20°C, forming a laminated film in which the core layer is sandwiched between two outer layers. Next, the laminated film was peeled off the drum, and both ends of the laminated film in the width direction were secured with tenter clips. The laminated film, secured with tenter clips, was dried while being stretched in the width direction at a stretching ratio of 1.1 times. After that, the laminated film was further dried by being transported between the rolls of a heat treatment device to produce support 1. The thickness of support 1 was 118 μm, and support 1 was a transparent support (Re < 200 nm, Rth: -50 to 50 nm). The lowest pKa among the hydrolyzed ester compounds contained in support 1 was 4.0, which is the pKa of at least one hydrolyzed compound represented by formula (A-3) above. Therefore, support 1 did not contain the specific ester compound.

[0109] [Polymer synthesis] Polymer 1 used in Example 1 was synthesized by the following procedure. A mixture of 38 parts by mass of toluene and 25 parts by mass of ethyl acetate was to be added over 2 hours at 80°C under a nitrogen atmosphere to a mixed solution of 60 parts by mass of ethyl acrylate, 240 parts by mass of methyl methacrylate, 98 parts by mass of toluene, 66 parts by mass of ethyl acetate, and 0.7 parts by mass of azoisobutyronitrile. 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 with a predetermined weight-average molecular weight, thereby obtaining polymer solution 1 containing polymer 1. The weight-average molecular weight Mw of the obtained polymer 1 was 100,000.

[0110] The polymers used in each example and comparative example are shown in the table below. The ratios of each monomer are by weight, and each polymer was synthesized according to the procedure described above using monomers in that ratio. However, for Comparative Example 3, a polymer was used which was a mixture of Aron S-1017 and Aron S-1030C in a weight ratio of 2:3.

[0111] [Preparation of coating solution] The polymer coating solution 1 used in Example 1 was obtained by the following procedure. The above polymer solution 1 was mixed with ethyl acetate and toluene so that the polymer solids concentration was 23% by mass and the ratio of ethyl acetate to all solvents was 57% by mass, thereby obtaining polymer coating solution 1. Furthermore, the silane coupling agent coating solution 1 used in Example 15 was obtained by adding 109.89 parts by mass of ethyl acetate to 0.11 parts by mass of the silane coupling agent KBM403 (γ-glycidoxypropyltrimethoxysilane) (manufactured by Shin-Etsu Chemical Co., Ltd.) and mixing. In other examples and comparative examples, polymer coating solutions were obtained according to the procedure described above.

[0112] [Formation of polymer layer] The cover film 1 used in Example 1 was obtained by forming a polymer layer on a support using the following procedure. A polymer coating solution 1 was applied to the support 1 using an applicator to form a coating film. The amount of polymer coating solution 1 applied was adjusted so that the thickness of the polymer layer after drying was 19 μm. As a drying process, the formed coating film was subjected to a blow-drying treatment by applying 100°C hot air at a wind speed of 3.2 m / s for 2 minutes, followed by a heat-drying treatment using an oven to evaporate the solvent, and a cover film 1 consisting of the support 1 and a polymer layer containing polymer 1 was prepared. The total film thickness of the support 1 and polymer layer in the cover film 1 was 137 μm. The cover films used in the other examples and comparative examples were also obtained according to the procedure described above. In Example 15, the cover film was formed by applying the polymer coating solution 15 and the silane coupling agent coating solution 1 using an extrusion overlay coating method during the polymer layer coating process. The amount of polymer coating solution 15 applied was adjusted to an amount that resulted in a polymer layer thickness of 19 μm after drying. The amount of silane coupling agent coating solution 1 applied resulted in a silane coupling agent concentration of 13.5 mg / m² relative to the surface area of ​​the transparent support. 2 The amount was adjusted to achieve this result.

[0113] <Measurement and evaluation methods> [Glass transition temperature of polymer layer] The polymer layer was peeled from the cover film, and the glass transition temperature (Tg(°C)) of the sample was measured by heating the polymer layer from -50°C to 100°C at a rate of 10°C / min using a differential scanning calorimeter (DSC).

[0114] [Fracture toughness value] Using a nanoindenter (iNano, G200 manufactured by Toyo Technica Co., Ltd.), a cube corner indenter was pressed into the polymer layer with a load of 20 mN, and the fracture toughness value K IC (MPa·m 0.5 ) was calculated. Table 1 described later shows the fracture toughness value K IC (MPa·m 0.5 ) in the following categories. ·A: Fracture toughness value K IC is 1.0 MPa·m 0.5 or more ·B: Fracture toughness value K IC is 0.2 MPa·m 0.5 or more and less than 1.0 MPa·m 0.5 ·C: Fracture toughness value K IC is less than 0.2 MPa·m 0.5

[0115] [Dissolution rate] [[ID=3८]]The dissolution rate (g·m -2 ·s -1 ) was calculated according to the method described in the part of Requirement 1 above. Specifically, the cover film was cut into a size of 24 mm in length and 120 mm in width, and the cut cover film was immersed in 1200 mL of xylene in a stainless steel container for 60 seconds. The xylene was dried at 150°C for 60 minutes. The difference between the mass before immersion and the mass after immersion was divided by the area of the cover film (m 2 ) and the immersion time (s) to calculate the dissolution rate (g·m -2 ·s -1 ).

[0116] [1 / X (reciprocal of viscosity)] 1 / X (cP -1 ) was calculated according to the method described in the part of Requirement 2 above.

[0117] [Chip prevention property] ​​The cover film was dried in a 120°C oven for 30 minutes until completely dry, and then cut with a push cutter. The results were evaluated sensorily according to the following criteria. For practical purposes, a rating of B or higher is preferred for its scrap-resistant properties. A: Almost no chips were observed, and there was almost no peeling or lifting of the polymer layer on the cut surface. • B: Almost no chips are visible, but slight lifting of the polymer layer is observed on the cut surface. • C: There is a lot of chipping, and there is a lot of peeling and lifting of the polymer layer on the cut surface.

[0118] [Void suppression] An automated encapsulation device, SCA-Film-J0 (manufactured by Sakura Seiki Co., Ltd.), was used to encapsulate a substrate (glass slide) by bonding it to a cover film. Xylene was used as the encapsulation solution. The glass slide size was 26 mm x 76 mm, and the cover film size was 24 mm x 50 mm. After allowing the encapsulated substrates to stand for one day, they were visually inspected to check for encapsulation defects. If two or more defects (bubble formation and partial delamination) with a size of 1 mm in diameter or larger were found in the encapsulated substrate, it was determined that an encapsulation defect had occurred. The encapsulation defect rate (%) was calculated by dividing the number of encapsulated substrates with defects by the total number of encapsulated substrates. The lower the rate of inclusion defects, the better the void suppression, and in practical terms, an inclusion defect rate of less than 8.0% is preferable.

[0119] [Adhesion] The above-mentioned encapsulation substrate was dried in a 50°C oven for one week. After drying, the peeling of the cover film was visually observed on the encapsulation substrate. The adhesion was evaluated according to the following classification based on the percentage of the area where peeling occurred. A rating of B or higher is preferable for practical purposes. A: The area of ​​the peeling is less than 5%. B: The area of ​​the peeling is 5% or more but less than 30%. • C: The area where peeling has occurred is 30% or more.

[0120] <Result> Table 1 shows the composition of the cover film used in each example and comparative example, as well as the measurement and evaluation results. In Table 1, the notation "Nk" in the weight-average molecular weight column represents N × 1000; for example, "100k" represents 100,000. In the table, the following abbreviations are used for monomers. EA: Ethyl acrylate • MMA: Methyl methacrylate BMA: n-butyl methacrylate • MEMA: 2-methoxyethyl methacrylate • EMA: Ethyl methacrylate iBMA: i-butyl methacrylate • tBMA: t-butyl methacrylate • BnMA: Benzyl methacrylate • 2EHMA: 2-Ethylhexyl methacrylate • LMA: Lauryl methacrylate • 2EHA: 2-ethylhexyl acrylate CHMA: Cyclohexyl methacrylate

[0121] [Table 1]

[0122] The results in Table 1 confirm that the cover film of the present invention achieves the desired effect. From a comparison of Examples 5 and 13 with other examples, the dissolution rate in xylene was found to be 0.01 to 0.15 g·m³. -2 ·s -1 Therefore, the above 1 / X is 0.010~0.060 cP -1 In this case, it was confirmed that it exhibits excellent void suppression and adhesion properties. A comparison of Example 4 with Examples 13 and 14 confirmed that when the weight-average molecular weight of the polymer is between 50,000 and 140,000, it exhibits superiority in either debris prevention or void suppression. A comparison of Examples 3, 5, and 12 with Examples 1, 2, 4, 6-11, and 16 confirmed that when the glass transition temperature of the polymer layer is 60°C or higher, excellent void suppression and adhesion properties are achieved. From a comparison of Examples 4, 6, 7, and 16 with other examples, it was confirmed that when the polymer contains repeating units derived from ethyl acrylate and repeating units derived from ethyl methacrylate, it exhibits excellent void suppression and debris prevention properties.

Claims

1. A cover film used to cover a specimen on a substrate, The cover film comprises a support and a polymer layer containing a polymer. The fracture toughness value of the polymer layer is 0.2 MPa·m ０．５ That's all. The in-plane retardation of the support at a wavelength of 590 nm is 1000 nm or less. A cover film that satisfies requirements 1 and 2. Requirement 1: The dissolution rate of the polymer layer in xylene is 0.01 to 0.25 g / m². －２ ・s －１ That is the case. Requirement 2: When the viscosity of a xylene solution with a solid content of 20% obtained by dissolving the polymer layer in xylene is X at 25°C, 1 / X must be between 0.005 and 0.060 cP. －１ That is the case.

2. The dissolution rate in xylene is 0.01 to 0.15 g / m³. －２ ・s －１ And the above 1 / X is 0.010 to 0.060 cP －１ The cover film according to claim 1.

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

4. The cover film according to claim 1 or 2, wherein the glass transition temperature of the polymer layer is 60°C or higher.

5. The cover film according to claim 1 or 2, wherein the polymer is a polymer comprising at least two repeating units derived from monomers selected from the group consisting of acrylate monomers and methacrylate monomers.

6. The cover film according to claim 1 or 2, wherein the polymer is a polymer comprising at least two repeating units derived from monomers selected from the group consisting of methyl methacrylate, ethyl acrylate, ethyl methacrylate, 2-methoxyethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, benzyl acrylate, 2-ethylhexyl methacrylate, and lauryl methacrylate.

7. The cover film according to claim 1 or 2, wherein the polymer comprises repeating units derived from ethyl acrylate and repeating units derived from ethyl methacrylate.

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