JP2011117829A - Cover film for microanalysis chip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic film for microanalysis cover excelling in transparency and processability, and being satisfactory in bondability with a resin substrate by heat. <P>SOLUTION: In a cover film for microanalysis chips acquired from a resin composition (C), containing 0-95 mass% of an acrylic resin (A) and 5-100 mass% of an acrylic-rubber-containing polymer (B), the light transmittance in the wavelength region between 400-800 nm is 90% or higher, the light transmittance in the wavelength region of 300 nm is 80% or higher, tensile strength at break is 10% or higher, and a softening temperature is 115°C or lower. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cover film for a micro analysis chip.

  A micro analysis chip or μTAS (Micro Total) that forms a fine channel or migration path on a silicon or glass substrate and performs chemical reaction, separation, analysis, etc. of a liquid sample such as nucleic acid, protein, blood, etc. in a micro space An apparatus called “Analysis Systems” has been put into practical use.

  However, those using glass substrates are not suitable for mass production and are very expensive, and development of inexpensive and disposable resin micro-analysis chips has been underway.

  As a resin micro-analysis chip, for example, an acrylic resin film is laminated as a cover material on a processed surface of a resin substrate that has been processed such as a groove on one side by a method such as an injection molding method or a photoresist method. A structure in which a flow path, a migration path, and the like are formed by applying a lid has been proposed (Patent Document 1).

  However, a micro analysis chip using a normal acrylic resin film as a cover film for a micro analysis chip is insufficient in transparency, making it difficult to observe transmitted light or observe fluorescence.

  In addition, cracks and cracks occur in the acrylic resin film in the process of manufacturing micro-analysis chips, such as the process of cutting the acrylic resin film into a product size for a cover film and the process of bonding the acrylic resin film to a resin substrate. Therefore, an acrylic resin film having sufficient processability is required.

  Furthermore, when an acrylic resin film is bonded to an acrylic resin substrate as a cover film by a heating method, an acrylic resin having adhesiveness at a lower temperature is used so as not to break the fine grooves on the substrate. A resin film is required.

  From such a situation, the appearance of a cover film for a micro analysis chip using an acrylic resin that is excellent in transparency and workability and has good bondability with a resin substrate by heat is expected.

JP 2004-286449 A

  An object of the present invention is to provide an acrylic film for a micro-analysis cover that is excellent in transparency and workability, and has good bondability with a resin substrate by heat.

  The gist of the present invention is a cover film for a micro analysis chip obtained from a resin composition (C) containing 0 to 95% by mass of an acrylic resin (A) and 5 to 100% by mass of an acrylic rubber-containing polymer (B). The light transmittance in the wavelength region of 400 to 800 nm is 90% or more, the light transmittance in the wavelength of 300 nm is 80% or more, the tensile fracture strain is 10% or more, and the softening temperature is 115 ° C. or less. Is a cover film for a micro analysis chip (hereinafter referred to as “the present film”).

  By using this film, the cover film surface of the obtained micro analysis chip is excellent in transparency, and since the occurrence of cracks and cracks is suppressed in the manufacturing process, it becomes possible to perform good transmitted light observation and fluorescence observation, Moreover, it becomes possible not to crush the fine groove formed in the microanalysis chip, and appropriate analysis can be achieved.

Hereinafter, the present invention will be specifically described.

Acrylic resin (A)

As the acrylic resin (A) used in the present invention, for example, a monomer of alkyl methacrylate (a-1) having an alkyl group having 1 to 4 carbon atoms (hereinafter referred to as “component (a-1)”). Monomer unit 0-50 mass% of vinyl monomer (a-2) (henceforth "(a-2) component") copolymerizable with unit 50-50 mass% and alkyl methacrylate (a-1). % Homopolymers or copolymers.

  Examples of the component (a-1) include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, and t-butyl methacrylate. These can be used alone or in combination. Of these, methyl methacrylate is preferred.

  Examples of component (a-2) include alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, and 2-ethylhexyl acrylate. Alkyl methacrylates having 5 or more carbon atoms such as 2-ethylhexyl (meth) acrylate; aromatic vinyl compounds such as styrene, α-methylstyrene and paramethylstyrene; and vinylcyan compounds such as acrylonitrile and methacrylonitrile Is mentioned. These can be used alone or in combination of two or more.

  In the present invention, the glass transition temperature (hereinafter referred to as “Tg”) of the acrylic resin (A) is preferably 60 ° C. or higher. By setting Tg to 60 ° C. or higher, the heat resistance of the film tends to be improved.

  Specific examples of the acrylic resin (A) include “Dianar BR series” manufactured by Mitsubishi Rayon Co., Ltd. and “Acrypet” manufactured by Mitsubishi Rayon Co., Ltd. (both are trade names).

Examples of the method for producing the acrylic resin (A) include a suspension polymerization method, an emulsion polymerization method, a bulk polymerization method, and a solution polymerization method.

Acrylic rubber-containing polymer (B)

Examples of the acrylic rubber-containing polymer (B) used in the present invention include, for example, JP-A-2008-208,197, JP-A-2007-327,039, JP-A-2006-289,672, and the like. And a multistage polymer polymerized in two or more stages containing a rubber polymer.

  In the present invention, the rubber polymer means a polymer having a Tg of less than 25 ° C.

  Tg can be calculated from the FOX equation using values described in the Polymer Handbook [Polymer HandBook (J. Brandrup, Interscience, 1989)].

  Specific examples of the acrylic rubber-containing polymer (B) of the present invention include the following polymer (B-1), polymer (B-2), and polymer (B-3).

  The polymer (B-1) is an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms (hereinafter referred to as “(b-α) component”) and an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms (hereinafter, In the presence of a rubber polymer obtained by polymerizing at least one monomer selected from “(b-β) component” and a monomer (1-A) containing a graft crossing agent, It is a polymer obtained by polymerizing the monomer (1-B) containing the component (b-β). Here, as a polymerization method of the monomers (1-A) and (1-B), any of a method of polymerizing in a batch or a method of polymerizing in two or more stages may be used.

  The polymer (B-2) polymerizes a monomer (2-A) containing at least one monomer selected from the (b-α) component and the (b-β) component and a graft crossing agent. Monomer (2-A) containing at least one monomer selected from the component (b-α) and the component (b-β) and a graft crossing agent in the presence of the polymer thus obtained. A monomer (2-B) having a composition different from that of the polymer is obtained to obtain a rubber polymer, and then a monomer (2-C) containing a component (b-β) in the presence of the rubber polymer. ).

  The polymer (B-3) polymerizes a monomer (3-A) containing at least one monomer selected from the (b-α) component and the (b-β) component and a graft crossing agent. In the presence of the polymer obtained in this manner, the monomer (3-B) containing the component (b-α) and the graft crossing agent was polymerized to obtain a rubber polymer, and then the rubber polymer In the presence, the monomer (3-C) containing at least one monomer selected from the (b-α) component and the (b-β) component and the graft crossing agent is polymerized, and then (b-β ) A polymer obtained by polymerizing the monomer (3-D) containing the component.

  In the present invention, if necessary, a vinyl monomer copolymerizable with the above monomer in the monomer at each stage used for obtaining the above acrylic rubber-containing polymer (B). Or a polyfunctional monomer. In addition, as a copolymerizable vinyl monomer or polyfunctional monomer, when it is desired to reduce autofluorescence with respect to ultraviolet light or visible light, a monomer containing a benzene ring such as styrene or alkyl-substituted styrene. It is preferable not to use the body.

  The amount of the monomer or monomer mixture containing 50% by mass or more of the component (b-β) used in the polymerization of the acrylic rubber-containing polymer (B) is rubber in terms of the transparency of the film. 60 mass parts or more are preferable with respect to 100 mass parts of polymers. (B-β) The amount of the monomer or monomer mixture containing 50% by mass or more of the component is 60 parts by mass or more, more preferably 100 parts by mass or more, still more preferably 150 parts by mass or more, and contains acrylic rubber. The dispersibility of the polymer (B) can be improved, and the reduction of the transmittance of the film and the occurrence of light scattering tend to be suppressed. The amount of the monomer or monomer mixture containing 50% by mass or more of the component (b-β) is the processability in the production process of the film and when the micro analysis chip is produced using the film. 400 parts by mass or less is preferable with respect to 100 parts by mass of the rubber polymer in terms of handling property and processability.

  Examples of the component (b-α) include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, and 2-ethylhexyl acrylate. It is done.

  Examples of the component (b-β) include the same components as the component (a-1).

  In the present invention, the graft crossing agent refers to a monomer having two or more different copolymerizable double bonds in one molecule.

  Examples of the graft crossing agent include copolymerizable α, β-unsaturated monocarboxylic acid or dicarboxylic acid allyl ester or methallyl ester, crotyl ester, triallyl cyanurate and triallyl isocyanurate. These can be used alone or in combination of two or more. Of these, allyl methacrylate and triallyl cyanurate are preferred.

  Examples of the copolymerizable monomer include aromatic vinyl compounds such as styrene, α-methylstyrene, and paramethylstyrene; and vinylcyan compounds such as acrylonitrile and methacrylonitrile. These can be used alone or in combination of two or more.

  In the present invention, the polyfunctional monomer means a monomer having two or more copolymerizable double bonds in one molecule.

  Examples of the polyfunctional monomer include ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, alkylene glycol dimethacrylate such as propylene glycol dimethacrylate; And polyvinyl benzene such as vinyl benzene; and alkylene glycol diacrylate. These can be used alone or in combination of two or more. Among these, alkylene glycol dimethacrylate is preferable, and 1,3-butylene glycol dimethacrylate is more preferable.

  When the acrylic rubber-containing polymer (B) is obtained by the sequential multi-stage polymerization method, the difference in refractive index of the monomer or monomer mixture used for the polymerization in each stage is preferably 0.05 or less. 0.03 or less is more preferable.

  By selecting the type and mass% of the monomer forming each stage so that the difference in refractive index of the monomer or monomer mixture used for polymerization in each stage is 0.05 or less, the transmittance A high acrylic film can be obtained. For example, in the case of a three-stage polymer, when the refractive index of the monomer at each stage is na, nb, and nc, the absolute value of (na-nc), the absolute value of (nb-nc), and (na-nb) ) Is preferably 0.05 or less, more preferably 0.03 or less.

  In the present invention, the refractive index is a refractive index value of a homopolymer at 20 ° C. described in “POLYMER HANDBOOK” (Wiley Interscience) (for example, polymethyl methacrylate 1.489, poly n-butyl). Acrylate 1.466, polystyrene 1.591 and polymethyl acrylate 1.476) were used. Further, the refractive index of the copolymer can be calculated from its volume ratio. As specific gravity used in that case, for example, polymethyl methacrylate 0.9360, poly n-butyl acrylate 0.8998, polystyrene 0.9060 and polymethyl acrylate 0.9564 are used.

  Examples of the mass average particle diameter of the rubber-containing polymer (B) include those having a size of about 0.01 to 0.5 μm. 3 μm or less is preferable.

  Examples of the method for producing the acrylic rubber-containing polymer (B) include a sequential multistage polymerization method.

  In the sequential multi-stage polymerization method, for example, an emulsion polymerization method and an emulsion suspension polymerization method in which the emulsion polymerization method is converted into a suspension polymerization system after the emulsion polymerization can be applied.

  In the emulsion polymerization method, an anionic, cationic or nonionic surfactant can be used as the surfactant used in preparing the emulsion, and among these, an anionic surfactant is preferable.

  Examples of the anionic surfactant include rosin soap; carboxylates such as potassium oleate, sodium stearate, sodium myristate, sodium N-lauroylsarcosate, dipotassium alkenyl succinate; sulfate esters such as sodium lauryl sulfate; Sulfonates such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium alkyldiphenyl ether disulfonate; phosphate esters such as sodium polyoxyethylene alkylphenyl ether phosphate; and sodium polyoxyethylene alkyl ether phosphate Of phosphoric acid ester salts. Among these, phosphate ester salts such as sodium polyoxyethylene alkyl ether sodium phosphate are preferred from the viewpoint of ecosystem conservation from endocrine disrupting chemicals.

  Specific examples of the surfactant include “NC-718” manufactured by Sanyo Chemical Industries, Ltd., “Phosphanol LS-529”, “Phosphanol RS-610NA” manufactured by Toho Chemical Co., Ltd., “Phosphanol RS-620NA”, “Phosphanol RS-630NA”, “Phosphanol RS-640NA”, “Phosphanol RS-650NA” and “Phosphanol RS-660NA”, manufactured by Kao Corporation "Latemul P-0404", "Latemul P-0405", "Latemul P-0406" and "Latemul P-0407" (all are trade names).

  Further, as a method for preparing an emulsion, for example, a method of charging a surfactant after charging the monomer in water, a method of charging the monomer after charging the surfactant in water, and a monomer A method in which water is added after a surfactant is charged therein. Among these, a method of charging a surfactant after charging the monomer in water and a method of charging the monomer after charging the surfactant in water are preferable.

  In the sequential multi-stage polymerization method, a mixing apparatus for preparing an emulsion by mixing a monomer that gives the first-stage polymer constituting the acrylic rubber-containing polymer (B) with water and a surfactant. Examples thereof include a stirrer equipped with a stirring blade; various forced emulsification devices such as a homogenizer and a homomixer; and a membrane emulsification device.

  In the present invention, the form of the emulsion may be either W / O type or O / W type dispersed structure, but it is O / W type in which monomer oil droplets are dispersed in water, and oil droplets in dispersed phase. An emulsion having a diameter of 100 μm or less is preferred.

  As a polymerization initiator used for the polymerization of the acrylic rubber-containing polymer (B), known ones can be mentioned, and the addition method thereof is either one of an aqueous phase or a monomer phase or an aqueous phase and a single amount. A method of adding to both of the body phases can be employed.

  Examples of the polymerization initiator include a redox initiator in which a peroxide, an azo initiator, and an oxidizing agent / reducing agent are combined. Among these, a redox initiator is preferable as the polymerization initiator, and a sulfoxylate initiator combined with ferrous sulfate, disodium ethylenediaminetetraacetate and Rongalite hydroperoxide is more preferable.

  In the present invention, the acrylic rubber-containing polymer (B) can be obtained by recovering the rubber-containing polymer (B) from the polymer latex produced by the above-described method.

Examples of the method for recovering the acrylic rubber-containing polymer (B) in a powder form from the polymer latex include a coagulation method using a salt or an acid, a spray drying method, and a freeze drying method.

Resin composition (C)

The resin composition (C) used in the present invention contains 0 to 95% by mass of the acrylic resin (A) and 5 to 100% by mass of the acrylic rubber-containing polymer (B).

  In the present invention, since the resin composition (C) eliminates the possibility of autofluorescence of the film as much as possible, the resin composition (C) includes a stabilizer, a lubricant, a processing aid, a plasticizer, and an impact resistance aid. It is preferable that the amount of additives such as an agent, a release agent, and an ultraviolet absorber be as small as possible or not blended.

  In the present invention, the film has a light transmittance in the wavelength region of 400 to 800 nm of 90% or more and a light transmittance in the wavelength of 300 nm of 80% or more. Therefore, the film contains an ultraviolet absorber that absorbs this wavelength region. Preferably not.

In addition, when an additive is blended in the resin composition (C), the additive to be blended includes a micro analysis chip reliability test such as a heat resistance test at 90 ° C. and a moist heat resistance test at 60 ° C. and 90 RH%. It is preferable to select one that does not bleed out.

This film

This film is a film for covering the fine groove formed on the resin substrate, and the flow path and the migration path can be formed by covering the fine groove formed on the resin substrate with the film.

  In the present invention, the micro-analysis chip means that a fine groove or the like is formed on a resin substrate using a thermoplastic resin such as an acrylic resin having high transparency and low autofluorescence with respect to ultraviolet light or visible light. This is a module in which a flow path and a migration path are formed by covering a groove or the like with a cover film after applying the above. The obtained microanalysis chip can perform chemical reaction, separation, analysis, and the like of a liquid sample such as nucleic acid, protein, blood, etc., using a flow path or a migration path.

  This film is obtained from the resin composition (C).

  The film has a light transmittance in the wavelength region of 400 to 800 nm of 90% or more, and a light transmittance in the wavelength of 300 nm of 80% or more, preferably 85% or more.

  When the light transmittance of this film satisfies the above conditions, light absorption and light scattering are small, and when analyzing a sample using a microanalysis chip using this film that has low fluorescence against ultraviolet light and visible light. Thus, it is possible to increase the measurement accuracy such as the absorption method for measuring the light absorption intensity of the sample and the fluorescence method for measuring the fluorescence intensity of the sample.

  Further, the tensile fracture strain of the present film is 10% or more, preferably 15% or more, more preferably 20% or more.

  By making the tensile fracture strain of the film 10% or more, the film is cracked in the process of manufacturing the micro analysis chip such as the process of bonding the cover film to the resin substrate and the process of cutting the micro analysis chip into the product size. Generation of cracks and cracks can be suppressed.

  Furthermore, the softening temperature of the film is 115 ° C. or lower, preferably 110 ° C. or lower.

  In the present invention, the softening temperature is a peak temperature of a loss coefficient tan δ of dynamic viscoelasticity measured at a measurement frequency of 0.1 Hz in accordance with JIS K7244-4.

  By setting the softening temperature of this film to 115 ° C. or lower, a micro-analysis chip is manufactured using a highly transparent thermoplastic resin such as polymethyl methacrylate having low fluorescence with respect to ultraviolet light and visible light as a substrate. In this case, the resin substrate and the present film can be bonded without breaking the groove on the resin substrate.

  In the present invention, the softening temperature of the film is preferably 90 ° C. or higher from the viewpoint of heat resistance of the micro analysis chip.

  As thickness of this film, 10-500 micrometers is preferable at the point of this film physical property, and 15-200 micrometers is more preferable. When the thickness of the cover film is 10 to 500 μm, the film has an appropriate rigidity, so that the film forming property is stable and the production of the film tends to be easy.

  Examples of the fine groove that can be covered using this film include those formed on one surface of a resin substrate by a method such as injection molding, hot pressing, and photoresist.

  As this film, what can be joined to a resin substrate by the following method is preferable.

Examples of the method of bonding the resin substrate and the film include a method of bonding by heat, a method of bonding using an adhesive or a solvent, a method of bonding using the adhesiveness of the resin substrate itself, and a corona on the resin substrate. Examples of the bonding method include surface treatment such as treatment or plasma treatment.
The cover film for a micro analysis chip of the present invention is preferably used in a method for heating a resin substrate and bonding it to the cover film.

  Examples of the method of joining by heat include a method of joining the cover film by heating the resin substrate using a hot plate, hot air, hot roll, ultrasonic wave, vibration, laser, or the like. The optimum method can be selected depending on the resin to be joined.

  Examples of the molding method for producing the film include melt extrusion methods such as a melt casting method, a T-die method, and an inflation method. Among these, the T-die method is preferable from the viewpoint of economy.

  In addition, when a liquid sample is allowed to flow through a flow path or a migration path in the microanalysis chip, stability of the flow of the liquid sample and stability of the analysis result are required. In such a case, it is preferable that the present film has high surface smoothness. Therefore, as a method for producing the present film, both surfaces of a film-like product obtained by melt extrusion from a T die are used as a roll surface or a belt surface. A production method in which the film is brought into contact with is preferable. The roll or belt used at this time is preferably metallic. The surface of the roll or belt is preferably a mirror surface.

  As a method for supplying the resin composition (C) at the time of molding for producing the film, for example, a method for directly supplying the resin composition (C) to a molding machine and various kneading machines for the resin composition (C) in advance. And a method of supplying the mixture kneaded and mixed by the above method.

  Examples of the kneader for kneading and mixing the resin composition (C) in advance with various kneaders include a single screw extruder, a twin screw extruder, a Banbury mixer, and a roll kneader.

  In addition, in this invention, when mix | blending an additive etc. with a resin composition (C), the method of supplying together with the time of the supply to the molding machine of said resin composition (C), or resin composition (C ) May be any method added when kneading.

Hereinafter, the present invention will be described using examples. In the following, “part” represents “part by mass”. Abbreviations indicate the following.
MMA: methyl methacrylate MA: methyl acrylate BA: n-butyl acrylate St: styrene AMA: allyl methacrylate BD: 1,3-butylene glycol dimethacrylate tBH: t-butyl hydroperoxide CHP: cumene hydroperoxide nOM: n-octyl Mercaptan emulsifier (1): sodium mono-n-dodecyloxytetraoxyethylene phosphate (manufactured by Toho Chemical Co., Ltd., trade name: Phosphanol RS-610NA)
EDTA: Ethylenediaminetetraacetic acid The mass average particle diameter of the acrylic rubber-containing polymer (B), the softening temperature of the cover film, the transmittance, the tensile fracture strain, the punching workability, and the heat bondability of the resin substrate and the cover film are evaluated. Was carried out by the following test method.
(1) Mass average particle diameter The mass average particle diameter of the rubber-containing polymer (B) obtained by emulsion polymerization was dynamically measured using a light scattering photometer DLS-700 (trade name, manufactured by Otsuka Electronics Co., Ltd.). Measured by light scattering method.
(2) Softening temperature Based on JIS K7244-4, the peak temperature of the loss coefficient tan δ of the dynamic viscoelasticity of the cover film measured at a measurement frequency of 0.1 Hz was defined as the softening temperature.
(3) Transmittance Using a UV-visible spectrophotometer V-630 (trade name, manufactured by JASCO Corporation), the transmittance at 300 nm and 400 to 800 nm of a 125 μm-thick cover film was measured.
(4) Tensile fracture strain Based on JIS K7127, the tensile fracture strain in the MD direction and the TD direction of a cover film having a film thickness of 125 μm was measured at a test speed of 50 mm / min.
(5) Punching workability Using a dumbbell testing machine (manufactured by Dumbbell Co., Ltd., trade name: Super Dumbbell), a cover film having a film thickness of 125 μm was punched, and the punching workability of the cover film was evaluated according to the following criteria.
○: No cracks were generated in the cover film.
Δ: 1 to 10 cracks occurred.
X: More than 10 cracks occurred.
(6) Heat bondability An acrylic resin (Mitsubishi Rayon Co., Ltd., trade name: Acrypet VH) was injection-molded to produce a resin substrate on which fine grooves were formed. The resin substrate has a side length of 50 mm and a thickness of 1 mm. Further, the fine groove formed on the resin substrate has two flow channel widths of 50 μm and 100 μm, the flow channel depth is 50 μm, and the groove length is 20 mm.

A cover film was placed on the surface of the resin substrate on which the fine grooves were formed, and the resin substrate and the cover film were bonded by holding for 1 minute at a temperature of 105 ° C. and a pressure of 0.1 MPa using a heating press. The heat bondability between the resin substrate and the cover film was evaluated according to the following criteria.
○: The resin substrate and the cover film are sufficiently bonded, and the cover film cannot be peeled off from the resin substrate.
X: The resin substrate and the cover film are not sufficiently joined, and the cover film can be peeled off from the resin substrate.
Example 1
(1) Preparation of acrylic rubber-containing polymer (B-i) After charging 10.8 parts of deionized water into a vessel equipped with a stirrer, 0.3 part of MMA, 4.5 parts of BA, 0.2 part of BD and AMA0 A monomer mixture containing 0.05 parts (Tg is −48 ° C.) was added together with 0.025 parts of CHP, and stirred and mixed at room temperature.

  Next, 1.1 parts of the emulsifier (1) was charged into the container while stirring the monomer mixture, and stirring was further continued for 20 minutes to prepare an emulsion.

  In a polymerization vessel equipped with a condenser, 139.2 parts of deionized water was added and heated to 75 ° C., then 0.20 part of sodium formaldehyde sulfoxylate and 0.0001 of ferrous sulfate were added to 5 parts of ion-exchanged water. And a mixture prepared by adding 0.0003 parts of EDTA were charged all at once into the polymerization vessel.

  Next, while stirring the mixture in the polymerization vessel under nitrogen, the above emulsion is dropped into the polymerization vessel over 8 minutes, and then the reaction is continued for 15 minutes to complete the polymerization. Obtained.

  Subsequently, a monomer mixture (Tg is −48 ° C.) containing 1.5 parts of MMA, 22.5 parts of BA, 1.0 part of BD, and 0.25 part of AMA in a polymerization vessel containing the rubber polymer (A). After dropwise addition in 90 minutes together with 0.016 part of CHP, the reaction was continued for 60 minutes to obtain a rubber polymer (I).

  Furthermore, a monomer mixture (Tg is 20 ° C.) containing 6.0 parts of MMA, 4.0 parts of BA and 0.075 parts of AMA in a polymerization vessel containing a rubber polymer (ii) together with 0.0125 parts of CHP for 45 minutes. Then, the reaction was continued for 60 minutes to obtain a polymer (U).

  Next, a monomer mixture (Tg is 84 ° C.) containing 55.2 parts of MMA, 4.8 parts of BA, 0.192 parts of nOM and 0.075 parts of tBH in a polymerization vessel containing the polymer (wax) over 140 minutes. After the dropwise addition, the reaction was continued for 60 minutes to obtain a latex of an acrylic rubber-containing polymer (B-i). The mass average particle diameter of the acrylic rubber-containing polymer (B-i) was 0.12 μm.

The resulting latex of the acrylic rubber-containing polymer (B-i) was filtered using a vibration type filtration device equipped with a SUS mesh (average opening 62 μm) as a filter medium, and then 3.5 parts of calcium acetate. Solidified in an aqueous solution containing The obtained coagulated product was washed and recovered with water and then dried to obtain a powdery acrylic rubber-containing polymer (B-i).
(2) Production of cover film 100 parts of powdery acrylic rubber-containing polymer (B-i) and 0.1 part of Irganox 1076 (trade name) manufactured by Ciba Specialty Chemicals Co., Ltd. as an antioxidant The mixture was mixed using a Henschel mixer, and the mixture was supplied to a degassing extruder (PCM-30, trade name, manufactured by Ikekai Tekko Co., Ltd.) heated to 230 ° C. and kneaded to obtain pellets.

  Dry pellets obtained by drying the above pellets at 80 ° C. for a whole day and night are supplied to a 40 mmφ non-vent screw type extruder (L / D = 26) equipped with a 300 mm wide T-die to cover a film thickness of 125 μm. A film was prepared. The extrusion conditions at that time were a cylinder temperature of 200 to 240 ° C, a T-die temperature of 250 ° C, and a cooling roll temperature of 85 ° C.

  Table 1 shows the evaluation results of the transmittance of the obtained cover film at wavelengths of 300 nm and 400 to 800 nm, tensile fracture strain, softening temperature, punching workability, and heat bondability between the resin substrate and the cover film.

（比較例１）
（１）アクリル系ゴム含有重合体（Ｂ−ロ）の調製
窒素雰囲気下、還流冷却器付き反応容器内に脱イオン水１４０部を入れ、８０℃に昇温した。

(Comparative Example 1)
(1) Preparation of acrylic rubber-containing polymer (B-ro) In a nitrogen atmosphere, 140 parts of deionized water was placed in a reaction vessel equipped with a reflux condenser, and the temperature was raised to 80 ° C.

  Next, 0.11 part of emulsifier (1), 0.02 part of sodium carbonate, 0.27 part of sodium formaldehyde sulfoxylate, 0.000075 part of ferrous sulfate and 0.000225 part of EDTA are put into the above reaction vessel. And stirred.

  Further, a mixture of 51.0 parts of n-BA, 11.5 parts of St, 0.56 part of AMA, 0.188 part of tBH and 1.0 part of emulsifier (1) was continuously added into the reaction vessel, and then 120 minutes. Polymerization was performed to obtain a rubber polymer latex.

  10 parts of deionized water and 0.15 part of sodium formaldehyde sulfoxylate were added to the resulting rubber polymer latex and held for 15 minutes.

  Next, while stirring the mixture in the polymerization vessel at 80 ° C. in a nitrogen atmosphere, 57.0 parts of MMA, 3.0 parts of MA, 0.2 part of nOM and 0.1 part of tBH were added dropwise over 100 minutes, and then at 80 ° C. Holding for 60 minutes to complete the polymerization, a latex of an acrylic rubber-containing polymer (B-B) was obtained. The mass average particle diameter of the acrylic rubber-containing polymer (B-B) was 0.12 μm.

The resulting latex of the acrylic rubber-containing polymer (B-B) was filtered using a vibration type filtration apparatus equipped with a SUS mesh (average opening 62 μm) as a filter medium, and then added to a 3% saline solution. And then solidified. The obtained coagulated product was washed and recovered with water and dried to obtain a powdery acrylic rubber-containing polymer (B-B).
(2) Production of cover film Instead of 100 parts of acrylic rubber-containing polymer (B-i), 22 parts of acrylic rubber-containing polymer (B-b) and acrylic resin (A-i) (Mitsubishi Rayon Co., Ltd.) ), Trade name: Acrypet VH) A cover film was obtained in the same manner as in Example 1 except that 78 parts of the mixture was used. The evaluation results of the obtained cover film are shown in Table 1.
(Comparative Example 2)
A microanalytical chip was produced in the same manner as in Comparative Example 1 except that the temperature of the heating press machine for bonding the resin substrate and the cover film was 115 ° C. Could not be formed.
(Comparative Examples 3 and 4)
A cover film was obtained in the same manner as in Comparative Example 1 except that the addition amounts of the acrylic rubber-containing polymer (B-ro) and the acrylic resin (A-i) were changed to the amounts shown in Table 1. The evaluation results are shown in Table 1.

Claims (1)

  A cover film for a microanalytical chip obtained from a resin composition (C) containing 0 to 95% by mass of an acrylic resin (A) and 5 to 100% by mass of an acrylic rubber-containing polymer (B), For micro-analysis chips having a light transmittance in the wavelength region of 800 nm of 90% or more, a light transmittance in the wavelength of 300 nm of 80% or more, a tensile fracture strain of 10% or more, and a softening temperature of 115 ° C. or less. Cover film.