WO2021187262A1

WO2021187262A1 - Cover film

Info

Publication number: WO2021187262A1
Application number: PCT/JP2021/009450
Authority: WO
Inventors: 健志梅原; 佳奈笹原; 顕夫田村; 裕三永田
Original assignee: 富士フイルム株式会社
Priority date: 2020-03-16
Filing date: 2021-03-10
Publication date: 2021-09-23

Abstract

The present invention provides a cover film that achieves both a reduction in floating during insertion and storability over time, is suitable for automatic insertion, and is to be used mainly in microscopes. The cover film of the present invention comprises a transparent support body and a polymer layer that is disposed on a surface of the transparent support body. The polymer layer contains a polymer, the weight average molecular weight of the polymer is 40,000-100,000, and the Hansen solubility parameter distance between the polymer and xylene is 3.57 MPa^0.5 or less.

Description

Cover film

The present invention relates to a cover film mainly used for a microscope, which is suitable for automatic encapsulation.

A cover film having an adhesive on a transparent support in advance is a base material (slide glass, etc.) on which a few drops of a solvent (xylene, etc.) capable of swelling and / or dissolving the adhesive are dropped, and is covered. A method is known in which a cover film and a base material are adhered (hereinafter, also referred to as "encapsulation") by automatically superimposing the sample on a base material on which an automatic encapsulation device is used. By this method, a specimen for microscopic observation in which the subject is fixed between the base material and the cover glass can be prepared.
Patent Document 1 describes a cover glass coated with an encapsulant that does not require the use of a liquid encapsulant because the encapsulant is applied to the glass.
Patent Document 2 states that even if the sample is stored in a roll form, blocking does not occur between the adhesive layer and the back surface of the support, and even if the sample is sealed with the cover glass and then stored for a long period of time, A cover glass for a microscope suitable for automatic encapsulation that does not cause film peeling due to change is described.

Jikkenhei 1-458116 Japanese Unexamined Patent Publication No. 11-101943

When the present inventors examined the above patent documents, the polymer of the encapsulant used in Patent Document 1 has a molecular weight of 3000 to 20000. Therefore, although it is soluble in a solvent, it has a small molecular weight. It was found that the storage time was not sufficient.
Further, it has been found that in the cover film of Patent Document 2, there is room for improvement in the dissolution rate of the adhesive in a solvent, and there are cases where the surface of the cover glass is floated (peeled) depending on the encapsulation conditions.

An object of the present invention is to provide a cover film mainly used for a microscope, which is suitable for automatic encapsulation and has both reduction of floating during encapsulation and storage stability over time.

As a result of diligent studies on the above problems, the present inventors have found that the above problems can be solved by the following configuration.

[1] A cover film having a transparent support and a polymer layer arranged on the surface of the transparent support.
The polymer layer contains a polymer and
The weight average molecular weight of the polymer is 40,000 to 100,000.
A cover film in which the Hansen solubility parameter distance between the polymer and xylene is 3.57 MPa ^{0.5 or less.}
[2] The cover film according to [1], wherein when the polymer layer is brought into contact with xylene, the time until the polymer layer dissolves is 300 seconds or less.
[3] The copolymer according to [1] or [2], wherein the polymer is a copolymer containing at least two kinds of repeating units based on a monomer selected from the group consisting of acrylate, methacrylate, styrene, and acrylamide. Cover film.
[4] The polymer is ethyl acrylate, n-butyl acrylate, methyl acrylate, cyclohexyl acrylate, benzyl acrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, methyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate. The cover film according to any one of [1] to [3], which is a copolymer containing at least two kinds of repeating units based on a monomer selected from the group consisting of acetoacetoxymethacrylate, styrene, and dimethylacrylamide.
[5] The cover film according to any one of [1] to [4], wherein the transparent support has a refractive index of 1.460 to 1.560.
[6] The cover film according to any one of [1] to [5], wherein the transparent support is cellulose triacetate.
[7] The cover film according to any one of [1] to [6], wherein the transparent support has a film thickness of 50 to 150 μm.
[8] The cover film according to any one of [1] to [7], wherein the total film thickness of the polymer layer and the transparent support is 150 μm or less.
[9] The cover film according to any one of [1] to [8], wherein the polymer layer contains a silane coupling agent.
[10] The silane coupling agent is one or more selected from the group consisting of γ-glycidoxypropyltrimethoxysilane and N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane. , [9].

According to the present invention, it is possible to provide a cover film mainly used for a microscope, which is suitable for automatic encapsulation and has both reduction of floating during encapsulation and storage stability over time.

Hereinafter, the present invention will be described in detail.
The constitutional requirements relating to the embodiments of the present invention may be described based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

In the present specification, the numerical range indicated by using "-" indicates a range including the numerical values before and after "-" as the minimum value and the maximum value, respectively. In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.

In the present specification, "% by mass" and "% by weight" are synonymous, and "parts by mass" and "parts by weight" are synonymous.
In the present specification, a combination of two or more preferred embodiments is a more preferred embodiment.
In the present specification, the amount of each component in the composition or layer is the sum of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Means quantity.
In the present specification, "(meth) acrylic" is a general term including acrylic and methacryl, and means "at least one of acrylic and methacrylic". Similarly, "(meth) acrylate" means "at least one of acrylate and methacrylate".
In the present specification, the refractive index means the refractive index for light having a wavelength of 550 nm, which is measured using NAR-2T manufactured by Atago, unless otherwise specified.

[Cover film]
The cover film of the present invention is a cover film having a transparent support and a polymer layer arranged on the surface of the transparent support, and the polymer layer contains a polymer and the weight average of the polymer. The molecular weight is 40,000 to 100,000, and the Hansen solubility parameter distance between the polymer and xylene is 3.57 MPa ^0.5 or less.
As a result of diligent studies, the present inventors have found that the polymer contained in the polymer layer that functions as an adhesive has a high affinity for xylene calculated from the Hansen SP value and is within an appropriate molecular weight range. As a result, it was found that the dissolution rate of xylene that can be used as a sealing solvent can be increased, the floating during sealing can be significantly reduced, and the storage stability over time can be achieved at the same time.
At the time of encapsulation, a solvent (xylene or the like) is dropped onto a base material (slide glass or the like), and a cover film is placed on the substrate (slide glass or the like) so that the polymer layers face each other to dissolve the polymer contained in the polymer layer. Then, the base material and the cover film are adhered by drying the solvent (xylene or the like).
At this time, if the solubility of the polymer in xylene is low, the effect as an adhesive is weakened, and floating is likely to occur on the base material. On the other hand, if the dissolution rate of the polymer in xylene is sufficiently high, the polymer spreads quickly and the adhesion between the base material and the upper portion (transparent support in the cover film) is increased, so that a gap is created between the two. It's hard to do. Further, if the molecular weight of the polymer used is small, the cohesive force of the polymer is weak and there is a problem that peeling or the like is likely to occur during long-term storage. It is possible to achieve both solubility.

[Polymer layer]
The cover film of the present invention has a polymer layer arranged on the surface of a transparent support described later.
In the following, first, the components contained in the polymer layer will be described, and then the characteristics of the polymer layer itself will be described.

<Polymer>
The polymer layer contains a polymer.
The polymer is also referred to as an adhesive polymer, an adhesive layer polymer, or the like.

Hansen parameters distance between the polymer and xylene (hereinafter also referred to as "specific HSP distance") is a 3.57MPa ^0.5 or less, more preferably 3.50MPa ^0.5 or less, 3.45 MPa ^0.5 or less Is more preferable.
There is no limit to the lower limit of the specific HSP distance, for example, the specific HSP distance is 0.00 MPa ^0.5 or more.
When the specific HSP distance is within the above range, the compatibility between the polymer and xylene is good, the dissolution rate of the polymer for xylene can be increased, and the floating of the cover film can be suppressed.
Xylene is a typical solvent used for encapsulation. Further, even if the solvent used for encapsulation is other than xylene, if the specific HSP distance is within the above range, good solubility in a general solvent used for encapsulation can be realized, which is a problem of the present invention. can be solved.
The specific HSP distance can be calculated from the Y-MB method using HSPiP (Hansen Solubility Parameter in Practice (ver5)).
Specifically, the specific HSP distance (unit: MPa ^0.5 ) is calculated by the following formula.
Formula specific HSP distance = (4 × (dDa-dDb) ² + (dPa-dPb) ² + (dHa-dHb) ² ) ^0.5
dDa: Dispersion term of polymer (unit: MPa ^0.5 )
dPa: Polymer polarization term (unit: MPa ^0.5 )
dHa: Hydrogen bond term of polymer (unit: MPa ^0.5 )
dDb: Dispersion term of xylene (unit: MPa ^0.5 )
dPb: Polarization term of xylene (unit: MPa ^0.5 )
dHb: Hydrogen bond term of xylene (unit: MPa ^0.5 )
The values of the dispersion term, the polarization term, and the hydrogen bond term of the polymer are determined based on the composition of the polymer identified by a known method.

The weight average molecular weight of the polymer is 40,000 to 100,000, preferably 40,000 to 70,000.
When the molecular weight of the polymer is not more than a predetermined value, the dissolution rate of the polymer in xylene can be increased, and the floating of the cover film can be suppressed.
When the molecular weight of the polymer is at least a predetermined value, the adhesion of the polymer after drying is good.
Unless otherwise specified, the weight average molecular weight (Mw) is a gel using a column of TSKgel GMHxL, TSKgel G4000HxL, TSKgel G2000HxL and / or TSKgel Super HZM-N (all trade names manufactured by Toso Co., Ltd.). It is a molecular weight converted by using a Permeation Chromatography (GPC) analyzer, using THF (tetrahydrofuran) as a solvent, detecting with a differential refractometer, and using polystyrene as a standard substance.

The Tg (glass transition temperature) of the polymer is preferably 80 ° C. or lower, more preferably 70 ° C. or lower, and even more preferably 60 ° C. or lower. There is no limitation on the lower limit of the Tg, and the Tg is preferably 20 ° C. or higher, more preferably 40 ° C. or higher.
When the Tg of the polymer is not more than a predetermined value, the brittleness of the polymer is improved, and chips are less likely to be generated when cutting the cover film.
When the Tg of the polymer is equal to or higher than a predetermined value, the softening point of the polymer rises and blocking of the cover film is less likely to occur.
The Tg of the polymer can be determined by collecting the polymer layer from the cover film by peeling or scraping it, and measuring the polymer layer with a differential scanning calorimeter (DSC).

The polymer preferably dissolves or swells in contact with the solvent used in the automatic encapsulation device, and more preferably dissolves. When the polymer comes into contact with the solvent and part or all of the polymer layer is dissolved, and then the solvent volatilizes and the dissolved polymer layer dries, the cover film adheres to the substrate.
Here, the fact that the polymer is dissolved in the solvent means that the polymer film having an area corresponding to a circle having a diameter of 20 mm and a film thickness of 40 μm is completely dissolved (completely dissolved) in 2 g of the solvent in an environment of 25 ° C. It means that it is possible.
The solvent is preferably an organic solvent, preferably xylene, toluene, ethyl acetate, methyl acetate, acetone, methyl ethyl ketone, or a mixed solvent thereof.

The polymer is preferably a (meth) acrylic resin. The (meth) acrylic resin can be prepared by a known method, and can be produced, for example, by polymerizing one or more kinds of (meth) acrylate monomers. The (meth) acrylic resin may contain a repeating unit other than the repeating unit based on the (meth) acrylate monomer (for example, the repeating unit based on the (meth) acrylamide monomer and / or the vinyl monomer).
The (meth) acrylic resin preferably has a content of a repeating unit based on the (meth) acrylate monomer of 50 to 100% by mass with respect to the total mass of the (meth) acrylic resin.

The polymer is preferably a polymer containing at least one type of repeating unit based on a monomer selected from the group consisting of acrylate, methacrylate, styrene, and acrylamide, and more preferably a copolymer containing at least two types. preferable.
The polymer may be the above-mentioned copolymer by containing two or more kinds of repeating units based on acrylate, or may be the above-mentioned copolymer by containing two or more kinds of repeating units based on methacrylate. The above copolymer may be obtained by containing two or more kinds of repeating units based on acrylamide.
Further, the polymer is made into the above-mentioned copolymer by containing a repeating unit based on two or more kinds of monomers selected from the group consisting of one kind of acrylate, one kind of methacrylate, styrene, and one kind of acrylamide. You may. For example, the polymer may be the above copolymer by containing a repeating unit based on one acrylate and styrene. Hereinafter, the same expressions are used to have the same intention.
The content of the repeating unit based on the monomer selected from the above group in the polymer is preferably 10 to 100% by mass, more preferably 60 to 100% by mass, and 90 to 100% by mass with respect to the total mass of the polymer. More preferred.
In the present specification, when it is expressed as a repeating unit based on a specific monomer, the repeating unit may be a repeating unit having a structure in which the specific monomer is polymerized. For example, when a repeating unit formed by using a monomer different from a specific monomer is modified or deprotected to obtain a repeating unit having the same structure as a repeating unit having a structure in which a specific monomer is polymerized, this is performed. The obtained repeating unit is also expressed as a repeating unit based on a specific monomer.

The polymer is preferably a polymer containing at least one type of repeating unit based on a monomer selected from the group consisting of alkyl acrylate, alkyl methacrylate, styrene, and acrylamide, and preferably a copolymer containing at least two types. More preferred.
The acrylamide is preferably monoalkylacrylamide or dialkylacrylamide. The two alkyl groups in the dialkylacrylamide may be the same or different.
The alkyl group moiety in the alkyl acrylate, the alkyl methacrylate, the monoalkyl acrylamide, and the dialkyl acrylamide may be linear or branched, and the number of carbon atoms is preferably 1 to 10.
The content of the repeating unit based on the monomer selected from the above group in the polymer is preferably 10 to 100% by mass, more preferably 60 to 100% by mass, and 90 to 100% by mass with respect to the total mass of the polymer. More preferred.

Polymers include ethyl acrylate, n-butyl acrylate, methyl acrylate, cyclohexyl acrylate, benzyl acrylate, lauryl acrylate, acetoacexyalkyl acrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, methyl methacrylate, etc. It is preferable that the polymer contains at least one repeating unit based on a monomer selected from the group consisting of cyclohexyl methacrylate, benzyl methacrylate, acetoacexialkyl methacrylate, lauryl methacrylate, styrene, dimethyl acrylamide, and isopropyl acrylamide. More preferably, it is a copolymer containing at least two kinds.
Among them, the polymers are ethyl acrylate, n-butyl acrylate, methyl acrylate, cyclohexyl acrylate, benzyl acrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, methyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate and acetoacetoxy. A polymer containing at least one repeating unit based on a monomer selected from the group consisting of methacrylate, styrene, and dimethylacrylamide is preferable, and a copolymer containing at least two kinds is more preferable.
The content of the repeating unit based on the monomer selected from the above group in the polymer is preferably 10 to 100% by mass, more preferably 60 to 100% by mass, and 90 to 100% by mass with respect to the total mass of the polymer. More preferred.

From the viewpoint of ease of observation with a microscope, the refractive index of the polymer layer is preferably close to that of the base material (glass having a refractive index of 1.56, etc.).
From the viewpoint of adjusting the refractive index of the polymer layer to a desired range, it is preferable that the polymer uses a repeating unit based on alkyl acrylate, alkyl methacrylate, and / or styrene.

When the cover film of the present invention is used as a cover film for a dyed specimen, the dye for dyeing may spread in the polymer layer, resulting in poor observability. In order to prevent this, it is also preferable to reduce the compatibility between the polymer and the dye for dyeing.
The compatibility between the polymer and the dye for dyeing (for example, eosin) can be judged from the Hansen solubility parameter distance of, for example, the Hansen solubility parameter distance between the polymer and the dye for dyeing is 12.00 MPa ^0.5 or more. Is preferable, 12.50 MPa ^0.5 or more is more preferable, and 13.00 MPa ^0.5 or more is further preferable. There is no limit to the upper limit of the Hansen solubility parameter distance, for example, the Hansen solubility parameter distance is 40.00 MPa ^0.5 or less.

The polymer preferably has a reduced content of residual monomers.
The content of the residual monomer is preferably 1.0% by mass or less with respect to the total mass of the polymer.
It is also preferable to synthesize the polymer by solution polymerization because the content of the residual monomer can be easily reduced.

The content of the polymer in the polymer layer is preferably 10 to 100% by mass, more preferably 60 to 100% by mass, and even more preferably 95 to 99.99999% by mass with respect to the total mass of the polymer layer.
The polymer may be used alone or in combination of two or more. When two or more kinds of polymers are used, it is preferable to use them in a ratio that does not cause turbidity in a dry film in which two or more kinds of polymers are mixed.

<Silane coupling agent>
The polymer layer may contain a silane coupling agent.
When the polymer layer contains a silane coupling agent, even if the cover film of the present invention is stored in a roll form, the polymer layer and the back surface of the transparent support (the side opposite to the surface of the transparent support on which the polymer layer is formed). It is preferable in that blocking is less likely to occur between the surface and the surface) and that the storage property over time is more excellent.

The silane coupling agent is preferably an organic silicon monomer. The silane coupling agent has two or more different reactive groups in the molecule, at least one of the reactive groups is a reactive group that chemically bonds with an inorganic substance, and at least one of the reactive groups chemically bonds with an organic material. It is also preferable that it is an organic silicon monomer as a reactive group.

Examples of the silane coupling agent include a silane coupling agent represented by a general formula.
YR-Si (CH ₃ ) _3-n X _n
In the above general formula, Y represents a vinyl group, a methacryl group, an epoxy group, an amino group, a mercapto group, or a chloro group.
R represents a single bond, a methylene group, or a polymethylene group. One or more of the methylene groups constituting the polymethylene group may be replaced with —O—, —S—, and / or —NH—. The number of carbon atoms in the polymethylene group is preferably 1 to 20, and the total number of atoms other than hydrogen atoms in the polymethylene group is preferably 2 to 20.
X represents a chloro group, a methoxy group, an ethoxy group, a methoxyethoxy group, an acetoxy group, a methylvinyloxy group, or an amino group. When there are a plurality of X's, the plurality of X's may be the same or different.
n is 2 or 3. In the above general formula, _{the values of n in "(CH 3} ) _3-n " and n in "X _n " are the same.

Examples of the silane coupling agent include vinyl trichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyl triethoxysilane, vinyl trimethoxysilane, γ- (methacryloxypropyl) trimethoxysilane, and β- (3,4-epyl). Cyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- ( From aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane One or more selected from the group consisting of γ-glycidoxypropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane. One or more selected from the group is more preferable, and one or more selected from the group consisting of γ-glycidoxypropyltrimethoxysilane and N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane. Is more preferable, and γ-glycidoxypropyltrimethoxysilane is particularly preferable.

The content of the silane coupling agent in the cover film of the present invention ^{is preferably 0.1 mg / m 2} or more, and more preferably 5 to 25 mg / m ² with respect to the area of the cover film.
The silane coupling agent may be used alone or in combination of two or more.

<Plasticizer>
The polymer layer of the present invention may contain a plasticizer.
By including the plasticizer, the compatibility of the polymer layer with the solvent (xylene, etc.) can be assisted, the dissolution rate when the polymer layer comes into contact with the solvent can be increased, and the brittleness of the polymer layer can be improved.
Known plasticizers can be used, and in particular, a plasticizer having high compatibility with the polymer to be used is preferable. For example, it is preferable that the distance between the plasticizer, the polymer, and the Hansen solubility parameter is small.

<Composition of polymer layer>
In the cover film of the present invention, the polymer layer may be arranged on the surface of the transparent support in direct contact with the transparent support, or may be arranged between the transparent support and the polymer layer via another layer. It may be arranged.
Further, the polymer layer may be composed of only one layer, or may be composed of two layers or a plurality of layers of three or more layers. When the polymer layer is composed of a plurality of layers, at least one of the plurality of layers contains a polymer.

From the viewpoint of ease of observation with a microscope, the refractive index of the polymer layer is preferably close to that of the base material (glass having a refractive index of 1.56, etc.).
For example, the refractive index of the polymer layer is preferably 1.460 to 1.560.

The polymer layer preferably has a high dissolution rate for xylene.
Specifically, when a polymer layer having a film thickness of 40 μm and having an area corresponding to a circle having a diameter of 20 mm is brought into contact with 2 g of xylene, the time until the polymer layer is completely dissolved (completely dissolved). (Hereinafter referred to as "xylene dissolution rate") is preferably 300 seconds or less, more preferably 270 seconds or less, further preferably 235 seconds or less, and particularly preferably 200 seconds or less. The lower limit of the xylene dissolution rate is not particularly limited, and the xylene dissolution rate is, for example, 160 seconds or more.
The polymer layer to be measured can be obtained by peeling the polymer layer from the cover film.
The temperature of the xylene and the polymer layer when measuring the xylene dissolution rate is 25 ° C.
When measuring the xylene dissolution rate, the polymer layer to be measured is first placed in a beaker having a capacity of 5 ml, and 2 g of xylene is placed therein to bring the polymer layer into contact with xylene. At this time, care should be taken not to overlap the surfaces of the polymer layers and the surfaces of the polymer layers with the bottom surface and / or the wall surface of the beaker. Also, when xylene is placed in the beaker, the polymer layer is prevented from being exposed from the liquid surface of xylene.
When the film thickness of the polymer layer that can be obtained by peeling from the cover film is other than 40 μm, first, the value X obtained by dividing the film thickness of the available polymer layer by 40 μm (= film thickness of the available polymer layer). ÷ 40 μm) is calculated. Then, the test was conducted under the condition that the amount of xylene used (2 g) and the capacity of the beaker (5 ml) were multiplied by X. The time obtained by dividing the time required for the polymer layer to completely dissolve (dissolve) by X in the test under such conditions is defined as the xylene dissolution rate.
Specifically, for example, when the polymer layer that can be obtained by peeling from the cover film is a polymer layer having a film thickness of 80 μm, a beaker having a capacity of 10 ml is used, and the amount of xylene to be brought into contact is 4 g. Then, the value obtained by dividing the time required for the polymer layer having a film thickness of 80 μm to completely dissolve (disappear) by 2 is defined as the xylene dissolution rate.

If the unevenness of the polymer layer is large, the contact area between the front surface of the polymer layer and the back surface of the transparent support becomes small when the cover film is laminated, so that blocking becomes difficult. The unevenness of the polymer layer preferably has an average height Rc of the surface of the polymer layer of 1.0 μm or more, more preferably 1.5 μm or more, and further preferably 2.0 μm or more. There is no particular limitation on the upper limit, but if the unevenness is large, a thicker polymer layer is required and the film thickness of the entire film becomes thicker. In addition, considering the ease of focusing when observing with a microscope, 3.5 μm or less is preferable.

The average height Rc can be measured by image analysis with a laser microscope. For example, it is calculated from the average value of Rc obtained from five arbitrarily selected locations (length of 1056 μm) using VK-9710 manufactured by KEYENCE CORPORATION.

The method of laying the polymer layer on the transparent support is not limited, and examples thereof include a coater and / or spray coating method, a casting method, and a transfer method.
Above all, a method of applying a coating liquid (polymer coating liquid) obtained by dissolving a polymer in a solvent (organic solvent or the like) on a transparent support and drying the formed coating film is preferable.
At that time, it is preferable that the type of solvent is wettability such that the polymer can be dissolved and repellency does not occur on the transparent support. Specific examples thereof include toluene, ethyl acetate, butyl acetate, acetone, and. A mixed solvent can be mentioned. Further, if a material capable of partially dissolving the surface of the transparent support or eluting a low molecular weight component such as a plasticizer in the transparent support is used as the solvent, the polymer may penetrate into the transparent support. It is possible to increase the adhesion between the polymer layer and the transparent support, and it is easy to prevent peeling.

When the polymer layer contains a silane coupling agent, as a method for incorporating the silane coupling agent in the polymer layer, for example, a polymer containing a polymer is contained on a transparent support by a method using the above-mentioned polymer coating solution or the like. After forming the layer, a silane coupling agent (or a silane coupling agent layer coating liquid containing a silane coupling agent) is further applied onto the polymer-containing layer to form a silane coupling agent layer. Can be mentioned. In this case, the polymer layer has a polymer-containing layer containing a polymer and a silane coupling agent layer containing a silane coupling agent.
Further, as a method of incorporating the silane coupling agent into the polymer layer, a polymer-containing layer containing the polymer (or a polymer coating liquid for forming the polymer-containing layer) and a silane coupling agent are used on the transparent support. There is also a method of simultaneously applying (multi-layer coating) a silane coupling agent layer (or a silane coupling agent layer coating liquid for forming a silane coupling layer) containing the above.
When the polymer layer has a silane coupling agent layer, the silane coupling agent tends to function effectively in a small amount.
As another method of incorporating the silane coupling agent into the polymer layer, for example, a polymer coating solution containing both the above-mentioned polymer and the above-mentioned silane coupling agent is applied onto a transparent support, and the above-mentioned polymer and silane are applied. Examples thereof include a method of forming a polymer layer which is a mixed layer in which a coupling agent is mixed.
Two or more of these methods may be used in combination. For example, the polymer layer may further have the silane coupling agent layer on the mixed layer.

The polymer layer also has a protective layer to more reliably prevent blocking when the polymer layer is scratched, stored at very high temperatures, and to adjust the curling balance. You may. Examples of the constituent material of the protective layer include polystyrene, synthetic polymers having a high glass transition temperature such as polymethylmethacrylate, and gelatin. The protective layer is also preferably present on the outermost layer of the polymer layer.

^{The coating amount of the polymer layer is preferably 1 to 50 g / m 2 and} more preferably 7 to 25 g / m ² with respect to the area of the cover film from the viewpoint of more excellent adhesiveness and maneuverability. The coating amount of the polymer layer is intended to be the dry weight after the solvent (organic solvent, etc.) has dried even when a coating liquid containing a solvent (organic solvent, etc.) is used for forming the polymer layer.
The film thickness of the polymer layer is preferably 5 to 200 μm, more preferably 10 to 100 μm, and even more preferably 15 to 60 μm.

[Transparent support]
As the transparent support, all the transparent supports known in the world can be used as the transparent support in the present invention.
In addition, in this specification, "transparent" means that the transmittance of visible light (light having a wavelength of 380 to 780 nm) is 80% or more. The transmittance is the ratio of transmitted light to incident light of the support.
Among them, the transparent support is preferably cellulose triacetate, polycarbonate, cellulose diacetate, or polyethylene terephthalate, and more preferably cellulose triacetate.
The film thickness of the transparent support is preferably 50 to 250 μm, more preferably 50 to 150 μm, and even more preferably 100 μm to 150 μm.
The transparent support may be coated with an undercoat layer, which is well known in the photographic photosensitive material industry, and may be subjected to surface treatment such as ultraviolet irradiation, corona discharge, or glow discharge.
Further, from the viewpoint of better microscopic property, the refractive index of the transparent support is preferably close to that of the base material (glass having a refractive index of 1.56, etc.). For example, the refractive index of the polymer layer is It is preferably in the range of −0.150 to +0.100, and more preferably in the range of −0.100 to +0.000 with respect to the refractive index of the base material.
The refractive index of the transparent support is, for example, preferably 1.400 to 1.600, more preferably 1.460 to 1.560.

In addition, the transparent support has a backing layer on the back surface in order to more reliably prevent blocking when the transparent support is scratched or stored at a very high temperature, and to adjust the curling balance. You may be. Examples of the constituent material of the backing layer include polystyrene, synthetic polymers having a high glass transition temperature such as polymethylmethacrylate, and gelatin.

The total film thickness of the polymer layer and the transparent support is preferably 300 μm or less, more preferably 150 μm or less, from the viewpoint of better operability and microscopic examination during microscopic observation. The lower limit is preferably 50 μm or more from the viewpoint of excellent handleability such as breakability and sealing property.

The cover film of the present invention can be preferably used for preparing a specimen for microscopic observation, and in addition, for example, a microscope for sealing a thin film on a substrate or protecting an underlayer with a laminate. It may be used for purposes other than the preparation of observation specimens.
Further, the base material to which the cover film is attached may be glass or a film-shaped material (resin or the like).

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded. Unless otherwise specified, "parts" and "%" are based on mass.

[Example 1]
(Preparation of coating liquid)
A polymer having a predetermined weight average molecular weight containing a repeating unit based on ethyl acrylate, a repeating unit based on methyl methacrylate, and a repeating unit based on cyclohexyl methacrylate in a mass ratio of 20/50/30, respectively, is subjected to solution polymerization. Synthesized. The above polymer was dissolved in a mixed solvent of toluene / ethyl acetate = 24/76 (mass ratio) so as to have a solid content concentration of 24% to obtain a polymer coating liquid 1. The solid content is intended to be all components excluding the solvent. The composition of the polymer ^{was confirmed by 1} H-NMR (Nuclear Magnetic Resonance Method).

Further, 109.89 parts by mass of ethyl acetate was added to 0.11 parts by mass of the silane coupling agent KBM403 (γ-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.), and the silane coupling agent layer coating solution 1 Got

(Making a cover film)
On a transparent support that is a transparent cellulose triacetate film (film thickness: 118 μm), an amount of polymer coating liquid 1 that makes the solid content film thickness (film thickness after drying) 19 μm, and the area of the surface of the transparent support. The silane coupling agent coating liquid 1 in an amount such that the coating concentration of the silane coupling agent was 13.5 mg / m ^{2 was applied by an extrusion layer coating method.} Then, the coating film formed on the cellulose triacetate film is dried in an environment of a wind speed of 3.2 m / s and 100 ° C. for 2 minutes, and further dried in an oven at 100 ° C. for 10 minutes on the surface. A cellulose triacetate film in which a polymer layer was arranged was obtained. The cellulose triacetate film was wound around a winding core having a diameter of 720 mm and allowed to elapse at 40 ° C. for 7 days to obtain a cover film 1.

[Example 2]
Polymer coating solution 1 except that the polymer used was replaced with a polymer having a predetermined weight average molecular weight containing repeating units based on each monomer in a mass ratio (mass%) as shown in Table 1 shown in the latter part. The polymer coating liquid 2 was prepared in the same manner as in the above. A cover film 2 was produced in the same manner as in Example 1 except that the polymer coating liquid 2 was used instead of the polymer coating liquid 1.

[Example 3]
Polymer coating solution 1 except that the polymer used was replaced with a polymer having a predetermined weight average molecular weight containing repeating units based on each monomer in a mass ratio (mass%) as shown in Table 1 shown in the latter part. The polymer coating liquid 3 was prepared in the same manner as in the above. A cover film 3 was produced in the same manner as in Example 1 except that the polymer coating liquid 3 was used instead of the polymer coating liquid 1.

[Example 4]
Polymer coating solution 1 except that the polymer used was replaced with a polymer having a predetermined weight average molecular weight containing repeating units based on each monomer in a mass ratio (mass%) as shown in Table 1 shown in the latter part. The polymer coating liquid 4 was prepared in the same manner as in the above. A cover film 4 was produced in the same manner as in Example 1 except that the polymer coating liquid 4 was used instead of the polymer coating liquid 1.

[Example 5]
Polymer coating solution 1 except that the polymer used was replaced with a polymer having a predetermined weight average molecular weight containing repeating units based on each monomer in a mass ratio (mass%) as shown in Table 1 shown in the latter part. The polymer coating liquid 5 was prepared in the same manner as in the above. A cover film 5 was produced in the same manner as in Example 1 except that the polymer coating liquid 5 was used instead of the polymer coating liquid 1.

[Example 6]
Polymer coating solution 1 except that the polymer used was replaced with a polymer having a predetermined weight average molecular weight containing repeating units based on each monomer in a mass ratio (mass%) as shown in Table 1 shown in the latter part. The polymer coating liquid 6 was prepared in the same manner as in the above. A cover film 6 was produced in the same manner as in Example 1 except that the polymer coating liquid 6 was used instead of the polymer coating liquid 1.

[Example 7]
Silane coupling agent KBM403 (γ-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.), KBM602 (N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) ) Was used to prepare the silane coupling agent layer coating liquid 2, and the cover film was used in the same manner as in Example 3 except that the silane coupling agent layer coating liquid 2 was used instead of the silane coupling agent coating liquid 1. 7 was prepared.

[Example 8]
A cover film 8 was produced in the same manner as in Example 3 except that a transparent polycarbonate film (film thickness: 118 μm) was used as the transparent support.

[Example 9]
A cover film 9 was produced in the same manner as in Example 3 except that the polymer coating liquid 3 was applied in an amount such that the solid content film thickness was 57 μm.

[Example 10]
A cover film 10 was produced in the same manner as in Example 3 except that the silane coupling agent coating liquid 1 was not used and only the polymer coating liquid 1 was coated in a single layer.

[Comparative Example 1]
Polymer coating solution 1 except that the polymer used was replaced with a polymer having a predetermined weight average molecular weight containing repeating units based on each monomer in a mass ratio (mass%) as shown in Table 1 shown in the latter part. The polymer coating liquid C1 was prepared in the same manner as in the above. A cover film C1 was produced in the same manner as in Example 1 except that the polymer coating liquid C1 was used instead of the polymer coating liquid 1.

[Comparative Example 2]
A polymer coating liquid C2 was prepared in the same manner as the polymer coating liquid 3 except that the weight average molecular weight of the polymer used was 130000. A cover film C2 was produced in the same manner as in Example 3 except that the polymer coating liquid C2 was used instead of the polymer coating liquid 3.

[Comparative Example 3]
A polymer coating liquid C3 was prepared in the same manner as the polymer coating liquid 1 except that the weight average molecular weight of the polymer used was 120,000. A cover film C3 was produced in the same manner as in Example 1 except that the polymer coating liquid 1 was used as a substitute.

[Comparative Example 4]
A polymer coating liquid C4 was prepared in the same manner as the polymer coating liquid 3 except that the weight average molecular weight of the polymer used was 30,000. A cover film C4 was produced in the same manner as in Example 3 except that the polymer coating liquid C4 was used instead of the polymer coating liquid 3.

[Measurement and evaluation]
The following measurements and evaluations were carried out for each cover film produced in Examples 1 to 10 and Comparative Examples 1 to 4.

(Polymer glass transition temperature)
The polymer layer peeled from the transparent support was measured by DSC under a heating condition of 10 ° C./min from −50 ° C. to 100 ° C. to determine the Tg of the polymer contained in the polymer layer.

(Hansen solubility parameter distance between polymer and xylene (specific HSP distance))
The Hansen solubility parameter distance (specific HSP distance) between the polymer contained in the polymer layer in the cover film of each example or comparative example and xylene was determined by the method described in the specification.

(Xylene dissolution rate)
The xylene dissolution rate of the polymer layer in the cover film of each Example or Comparative Example was determined by the method described in the specification.

(Enclosed)
The cover film was bonded to the slide glass using the cover aid automatic encapsulation device SCA-Film-J0 (Sakura Seiki Co., Ltd., Japan) to obtain a slide glass with a cover film.

(Evaluation of float)
The slide glass with a cover film obtained by encapsulation was allowed to stand at room temperature (25 ° C.), the surface was checked after 1 day, and the sealing surface (cover film) of the slide glass with a cover film was lifted (peeled). ) Was observed and evaluated in the light of the following categories.
1: No float at all 2: Very slight float (level at which there is no practical problem in observation with a microscope)
3: There is a small amount or a large amount of float (bad evaluation than 2)

(Evaluation of microscopic examination)
A linear scratch was made in advance on the surface of the slide glass used for encapsulation on the cover film side, and after encapsulation, the scratch on the glass surface was observed from the cover film side using a microscope. Based on the observed scratch distortion, the microscopic property of the cover film was evaluated based on the following criteria. If it is 1 to 3 in the following criteria, there is no problem in practical use.
1: No distortion on the wound 2: Slightly distorted on the wound 3: Slightly distorted on the wound 4: Distortion on the wound.

(Evaluation of storage over time)
A slide glass with a cover film obtained by encapsulation was placed in an environment of 35 ° C. and 80% RH for 7 days to perform a film peeling acceleration test. The cover film after the accelerated test was visually observed, and the storage stability over time was evaluated according to the following criteria from the rate of increase in air bubbles and / or peeling in the cover film before and after the accelerated test. If it is 1 to 3 in the following criteria, there is no problem in practical use.
1: Bubbles and / or peeling do not increase 2: Bubbles and / or peeling increase slightly 3: Bubbles and / or peeling increase slightly (bad evaluation than 2)
4: Bubbles and / or peeling increase (bad evaluation than 3)

The table below shows the production conditions, measurement results, and evaluation results of the cover film.
In the table, the column "Monomers constituting the polymer (mass%)" indicates the content (mass%) of the repeating units based on each monomer constituting the polymer with respect to the total mass of the polymer.

From the results shown in the table, it was confirmed that the cover film satisfying the present invention is less likely to float (peeling) during encapsulation and has good storage stability over time.

It was confirmed that the polymer layer preferably contains a silane coupling agent and more preferably contains γ-glycidoxypropyltrimethoxysilane from the viewpoint of better storage stability over time (Examples 3 and 7). Refer to the comparison of the results of 10).

It was confirmed that the refractive index of the transparent support is preferably 1.460 to 1.560 from the viewpoint of better microscopic examination (see comparison of the results of Examples 3 and 8 and the like).

It was confirmed that the total film thickness of the polymer layer and the transparent support is preferably 150 μm or less from the viewpoint of better microscopic examination (see comparison of the results of Examples 3 and 9).

It was confirmed that the xylene dissolution rate of the polymer layer is preferably 200 seconds or less from the viewpoint of further suppressing the floating (see comparison of the results of Example 1 and other examples).

In Examples 1 to 9, a silane coupling agent was mixed with the polymer coating liquid to prepare a polymer coating liquid containing both the polymer and the silane coupling agent, and only such a polymer coating liquid was applied in a single layer. Similar results were obtained even when a polymer layer, which is a mixed layer in which the polymer and the silane coupling agent were mixed, was formed to prepare a cover film and evaluated.
The amount of the silane coupling agent mixed with the polymer coating liquid was adjusted so that the coating concentration of the silane coupling agent with respect to the area of the cover film was the same as in Examples 1 to 9.

Claims

A cover film having a transparent support and a polymer layer arranged on the surface of the transparent support.
The polymer layer contains a polymer and
The weight average molecular weight of the polymer is 40,000 to 100,000.
A cover film in which the Hansen solubility parameter distance between the polymer and xylene is 3.57 MPa 0.5 or less.
When the polymer layer having a film thickness of 40 μm and having an area corresponding to a circle having a diameter of 20 mm is brought into contact with 2 g of xylene, the time until the polymer layer is completely dissolved is 300 seconds or less. The cover film according to claim 1.
The cover film according to claim 1 or 2, wherein the polymer is a copolymer containing at least two kinds of repeating units based on a monomer selected from the group consisting of acrylate, methacrylate, styrene, and acrylamide.
The polymer is ethyl acrylate, n-butyl acrylate, methyl acrylate, cyclohexyl acrylate, benzyl acrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, methyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, acetoacetoxy. The cover film according to any one of claims 1 to 3, which is a copolymer containing at least two kinds of repeating units based on a monomer selected from the group consisting of methacrylate, styrene, and dimethylacrylamide.
The cover film according to any one of claims 1 to 4, wherein the transparent support has a refractive index of 1.460 to 1.560.
The cover film according to any one of claims 1 to 5, wherein the transparent support is cellulose triacetate.
The cover film according to any one of claims 1 to 6, wherein the transparent support has a film thickness of 50 to 150 μm.
The cover film according to any one of claims 1 to 7, wherein the total film thickness of the polymer layer and the transparent support is 150 μm or less.
The cover film according to any one of claims 1 to 8, wherein the polymer layer contains a silane coupling agent.
The claim that the silane coupling agent is one or more selected from the group consisting of γ-glycidoxypropyltrimethoxysilane and N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane. 9. The cover film according to 9.