Fluororesin container

Abstract

To provide a container capable of increasing visibility of microscopy.SOLUTION: A fluororesin container includes: a bottom wall; a lateral wall standing around the bottom wall; and an opening defined by the upper end part of the lateral wall. The fluororesin is a fluorine-containing terpolymer. The fluorine-containing terpolymer has a refractive index of 1.32 or more and 1.34 or less. In a film of the fluorine-containing terpolymer with a thickness of 2 mm, light transmittance is 85% or more at 650 nm in measurement by a spectrophotometer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a container made of a fluororesin.

Background Art

[0002] Conventional containers for cell observation are made of transparent glass or transparent resin. Cells and a culture solution are added into the container, and the cells are observed with a microscope or the like. When using a container having a shape such as a Petri dish with a flat bottom surface, if the viewing direction of the microscope observation and the upper and lower ends of the bottom surface are completely perpendicular, no refraction of light rays occurs on the wall surface of the container. Therefore, it is possible to completely observe the cells without recognizing the shape of the container.

[0003] However, if there is even a slight angle between the viewing direction of the microscope observation and the wall surface of the container, due to the difference in refractive index between a culture solution such as water and transparent glass or transparent resin, light rays are refracted on the wall surface of the container. Therefore, the shape of the container is visually recognized within the observation range of the microscope, which hinders the observation.

[0004] In addition, when using a container having a Petri dish shape, since the bottom surface is slightly curved, the shape of the container may be visually recognized. Further, in a container having a Petri dish shape, when a plurality of wells are provided in a concave shape on the bottom surface to accommodate individual cells, the shape of the wells is more prominently visually recognized.

[0005] As another container for cell observation, a frustum-shaped container having a U-shaped longitudinal section is known. Such a container has an advantage that since the central portion of the bottom surface is the deepest and the width gradually narrows toward the bottom surface, it is easy to gather the observation object at the center of the container and easy to observe.

[0006] On the other hand, even in such a shaped container, due to the difference in refractive index between a culture solution such as water and transparent glass or transparent resin, light rays are refracted on the wall surface of the container. Therefore, similar to the container having a Petri dish shape, the shape of the container is visually recognized within the observation field of the microscope, which hinders the observation.

[0007] In order to suppress the decrease in visibility caused by such a difference in refractive index, it is known to use a fluororesin having a refractive index substantially equal to that of water and being transparent in the visible region as the material of the container. Patent Document 1 discloses a cell culture substrate made of a fluororesin having a refractive index of 1.33 or more and 1.34 or less and being transparent in the visible light region, and having hydrophilicity imparted to its surface.

[0008] However, although the fluororesin disclosed in Patent Document 1 can be used to produce a thin plate such as a substrate, it is difficult to produce a container having a three-dimensional shape, and thus it is not suitable as a material for a cell observation container. Further, in order to use such a fluororesin as a cell culture substrate, it is necessary to irradiate the substrate surface with a laser or the like to impart hydrophilicity, which leads to an increase in manufacturing cost.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] The present invention provides a container capable of enhancing the visibility of microscopic observation.

Means for Solving the Problems

[0011] The container according to an embodiment of the present invention is a fluororesin container including a bottom wall, a side wall erected around the bottom wall, and an opening defined by an upper end portion of the side wall, wherein the fluororesin is a fluorine-containing terpolymer, and the fluorine-containing terpolymer has a refractive index of 1.32 or more and 1.34 or less. For the film with a thickness of 2 mm of the fluorine-containing terpolymer, the light transmittance at 650 nm measured using a spectrophotometer is 85% or more.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide a container capable of enhancing the visibility of microscopic observation.

Brief Description of the Drawings

[0013]

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Embodiments for Carrying out the Invention

[0014] Hereinafter, the container according to the embodiment of the present invention will be described in detail with reference to the drawings. It should be noted that the container described below has a three-dimensional shape provided with a certain space capable of accommodating substances, and thin plate-like members such as substrates, plates, and films that do not have such a space are not included. Also, the room temperature is within the range of 23°C ± 5°C.

[0015] <Container> The container according to this embodiment is a container made of fluororesin, and includes a bottom wall, a side wall erected around the bottom wall, and an opening defined by an upper end portion of the side wall. Such a container is a molded body formed of a fluororesin having a predetermined refractive index and light transmittance and formed into a predetermined three-dimensional shape.

[0016] The container according to this embodiment is preferably used as a container for cell observation. Such a container for cell observation is a container for accommodating cells and a culture solution and observing the cells with a microscope or the like. In addition to being a container for cell observation, the container can also be used, for example, as a container for cell accommodation, a container for cell culture, a container for cell transportation, or a container for cell preservation.

[0017] Examples of the cells accommodated in the container for cell observation include cells of humans and animals such as hair follicle primordia and hepatocytes. The size of the cells is not particularly limited and depends on the observation sample, but is, for example, in the range of 1 μm or more and 100 μm or less. As the culture solution, water, DMEM medium (Dulbecco's Modified Eagle Medium), etc. can be used, and it is preferable that the refractive index of the culture solution is in the range of 1.32 or more and 1.34 or less, which is the same as the refractive index of the fluororesin described later, and more preferably substantially the same as the refractive index of the material of the container used.

[0018] FIG. 1 is an example of an embodiment of such a container, and FIG. 2 is a longitudinal sectional view of the container shown in FIG. 1. The container 10 shown in FIGS. 1 and 2 includes a bottom wall 11, a side wall 12 erected around the bottom wall 11, and an opening 13 defined by the upper end portion of the side wall 12. The inner surface of the bottom wall 11 is a flat surface, and such a container 10 has a dish shape like a petri dish. The size of the bottom wall 11 is not particularly limited. For example, the outer diameter is 30 mm or more and 200 mm or less, and the thickness is 0.5 mm or more and 3 mm or less.

[0019] The side wall 12 is integrally formed with the peripheral edge of the bottom wall 11 and is provided substantially vertically on the inner surface of the bottom wall 11. The side wall 12 may have an angle of 90° or more and 100° or less with respect to the inner surface of the bottom wall 11. The size of the side wall 12 is not particularly limited. For example, the height is 5 mm or more and 25 mm or less, and the thickness is 0.5 mm or more and 3 mm or less. The height from the inner surface of the bottom wall 11 of the container 10 to the opening 13 is formed to be equal over the entire circumference of the opening 13.

[0020] In a container having a petri dish shape, a plurality of wells may be provided on the inner surface of the bottom wall. By providing such wells, the contents can be separated and observed in individual wells. The container 10 shown in FIG. 3 includes a plurality of wells 14 provided in a concave shape on the inner surface of the bottom wall 11. Such a plurality of wells 14 are formed in a pattern on the inner surface of the bottom wall 11, and the plurality of wells 14 can be arranged at equal intervals. Also, the arrangement pattern of the plurality of wells 14 is not particularly limited. For example, they can be arranged at a predetermined interval vertically and horizontally. In the plurality of wells 14, the interval between adjacent wells 14 is preferably smaller than the maximum width of the opening of the well 14. For example, it can be in the range of 10 μm or more and 100 μm or less. Also, the interval between the well 14 adjacent to the side wall 12 and the side wall 12 can be made smaller than the maximum width of the opening of the well 14. For example, it can be in the range of 10 μm or more and 300 μm or less.

[0021] In the example shown in FIG. 3, the well 14 has a generally frustum - like pyramidal shape as a whole, and as shown in FIG. 4, the well 14 has a substantially triangular cross - sectional shape. The well 14 has side surfaces inclined with respect to the direction perpendicular to the bottom surface 14b such that the inner diameter gradually decreases from the opening 14a to the bottom surface 14b. The depth from the opening 14a to the bottom surface 14b of the well 14 is not particularly limited, but for example, it can be in the range of 100 μm or more and 300 μm or less. Also, the opening width of the well 14 is not particularly limited and can be in the range of 100 μm or more and 600 μm or less.

[0022] The shape of the well 14 is not limited to the generally frustum - like pyramidal shape shown in FIGS. 3 and 4. For example, it may have a cylindrical shape with a rectangular cross - sectional shape, a frustum - like conical shape with a trapezoidal cross - sectional shape, or a conical shape with a triangular cross - sectional shape. The well 14 preferably has an inclined surface configured such that the depth from the opening 14a to the bottom surface 14b is maximum at the central portion of the bottom surface 14b so that the contents can be held at the central portion of the bottom surface 14b of the well 14.

[0023] FIG. 5 is an example of a container according to another embodiment, and FIG. 6 is a longitudinal cross - sectional view of the container shown in FIG. 5. The container 20 shown in FIGS. 5 and 6 includes a bottom wall 21, a side wall 22 erected around the bottom wall 21, and an opening 23 defined by the upper end portion of the side wall 22. The inner surface of the bottom wall 21 has a flat surface 21a, and such a container 20 has a frustum - like conical shape like a cup. FIG. 7 is the same as the container 20 shown in FIG. 6 except that the longitudinal cross - sectional shape is U - shaped, and the bottom wall 21 has a hemispherical shape along the thickness direction. In the container 20 shown in FIG. 7, the central portion 21b of the bottom wall 21 is the deepest, and since the contents gather at the central portion 21b, the contents are easier to observe. The size of the bottom wall 21 is not particularly limited, but for example, the outer diameter is 1 mm or more and 10 mm or less, and the thickness is 0.5 mm or more and 3 mm or less. Also, the size of the side wall 21 is not particularly limited, but for example, the height is 5 mm or more and 20 mm or less, and the thickness is 0.5 mm or more and 3 mm or less.

[0024] In FIGS. 6 and 7, the side wall 22 is integrally formed with the peripheral edge of the bottom wall 21 and is provided substantially vertically on the inner surface of the bottom wall 21. The side wall 22 may have an angle of 90° or more and 100° or less with respect to the inner surface of the bottom wall 21. The height from the inner surface of the bottom wall 21 of the container 20 to the opening 23 is formed to be equal over the entire circumference of the opening 23.

[0025] [Fluororesin] Since the fluororesin, which is the material of the container, is a fluorine-containing terpolymer, it has higher mechanical strength, better transparency, and higher reactivity than a fluorine-containing binary copolymer, making it easier to obtain a copolymer. Further, the fluorine-containing terpolymer has a refractive index of 1.32 or more and 1.34 or less. When a film with a thickness of 2 mm of the fluorine-containing terpolymer is produced, it has a light transmittance of 85% or more at 650 nm measured using a spectrophotometer for the film. Such a fluorine-containing terpolymer is transparent in the visible light region and has a refractive index similar to that of water (about 1.33), which is generally used as a culture solution. Therefore, for example, when observing cells in a culture solution contained in such a container with a microscope, even if there is a wall surface that is not perpendicular to the line of sight in the line-of-sight direction, the refraction of light at that wall surface is suppressed. As a result, the shape of the container is not visually recognized within the observation field of view, and it becomes possible to observe the cells, enhancing the visibility of microscope observation. In particular, a container having a shape as shown in FIG. 7 is likely to have its shape visually recognized during microscope observation and may interfere with the observation. Therefore, by using such a specific fluororesin as the material of the container, it is possible to prevent the shape of the container from being visually recognized within the observation field of view.

[0026] The fluorine-containing terpolymer is preferably a terpolymer of 5% by weight or more and 98% by weight or less, preferably 15% by weight or more and 98% by weight or less of tetrafluoroethylene, 1% by weight or more and 40% by weight or less, preferably 1% by weight or more and 35% by weight or less of perfluoro(ethyl vinyl ether), and 1% by weight or more and 55% by weight or less, preferably 1% by weight or more and 50% by weight or less of perfluoro(propyl vinyl ether). When the copolymerization amount of perfluoro(ethyl vinyl ether) is 1% by weight or more, the decrease in light transmittance can be suppressed. When the copolymerization amount of perfluoro(ethyl vinyl ether) is 40% by weight or less, the softening of the copolymer can be prevented and the decrease in mechanical strength can be suppressed. Also, when the copolymerization amount of perfluoro(propyl vinyl ether) is 1% by weight or more, the decrease in mechanical strength and light transmittance can be suppressed. Furthermore, since perfluoro(propyl vinyl ether) has low radical reactivity with respect to tetrafluoroethylene and poor copolymerizability, if the copolymerization amount of perfluoro(propyl vinyl ether) is too large, it may cause a decrease in the molecular weight of the fluorine-containing terpolymer itself. Therefore, when the copolymerization amount of perfluoro(propyl vinyl ether) is 55% by weight or less, the decrease in the molecular weight of the fluorine-containing terpolymer itself can be prevented and the decrease in mechanical strength can be suppressed.

[0027] In the fluorine-containing terpolymer having such a copolymer composition, the copolymerization ratio of perfluoro(propyl vinyl ether) to perfluoro(ethyl vinyl ether) is generally preferably 0.2 or more, more preferably 1.0 or more, and even more preferably 1.0 or more and 3.0 or less by weight. When this copolymerization ratio is less than 0.2, the resulting fluorine-containing terpolymer has properties close to those of a tetrafluoroethylene-perfluoro(ethyl vinyl ether) copolymer, and there is a risk that the effect of improving mechanical properties such as tensile breaking strength will be reduced. Also, the more perfluoro(propyl vinyl ether) there is, the more difficult it is for the resin in the molten state to deform due to the entanglement of the side-chain perfluoropropoxy groups, and the resin sag during container molding is effectively suppressed. Therefore, when this copolymerization ratio is 1.0 or more, it greatly contributes to the uniformity of the thickness of the bottom wall and side walls when molding a container, and as a result, the variation in light transmittance is suppressed. In particular, when the copolymerization ratio of perfluoro(propyl vinyl ether) to perfluoro(ethyl vinyl ether) is 1.0 or more and 3.0 or less, a container excellent in tensile breaking strength and light transmittance can be molded.

[0028] Also, the fluorine-containing terpolymer preferably has a specific melt viscosity of 0.1×10 3 Pa·s or more and 110×10 3 Pa·s or less at 372°C. When the specific melt viscosity is 0.1×10 3 Pa·s or more, a container having sufficient mechanical strength can be obtained, and when the specific melt viscosity is 110×10 3 Pa·s or less, a significant decrease in moldability can be suppressed. The fluorine-containing terpolymer having such a specific melt viscosity imparts sufficient mechanical strength to the molded article and is excellent in moldability, so it greatly contributes to the integral molding of a container having a three-dimensional shape. Also, the glass transition temperature of the fluorine-containing terpolymer is preferably 20°C or more, whereby a decrease in mechanical strength at room temperature can be suppressed.

[0029] As the mechanical strength imparted by the fluorine-containing terpolymer to the molded article, the tensile breaking strength at 20°C measured in accordance with ASTM-D-1708 is preferably 15 MPa or more, more preferably 20 MPa or more. Also, the tensile breaking strength at 150°C measured in accordance with ASTM-D-1708 is preferably 1 MPa or more, more preferably 2 MPa or more.

[0030] [Manufacturing method of fluororesin] The fluorine-containing terpolymer can be obtained by a copolymerization reaction of tetrafluoroethylene, perfluoro(ethyl vinyl ether) and perfluoro(propyl vinyl ether), and is produced, for example, by a solution polymerization method, a solution suspension polymerization method or the like. Among these, the solution suspension polymerization method using water as a medium is preferable from the viewpoints of polymerization rate, heat removal of polymerization heat, suppression of coloring of the molded article, etc. In the solution suspension polymerization method, the copolymerization rate of perfluoro(propyl vinyl ether) having low copolymerizability with tetrafluoroethylene can be effectively increased, and it becomes possible to economically produce a terpolymer having a large vinyl ether copolymerization amount.

[0031] In the solution suspension polymerization method, examples of the water-insoluble or water-difficultly soluble solvent used in the mixing system with water include hydrochlorofluorocarbon, hydrofluorocarbon, perfluorocarbon, etc. From the viewpoint of preventing global environmental pollution, it is preferable to use a hydrofluorocarbon or perfluorocarbon having a small ozone depletion coefficient. The mixing ratio of these solvents with water can be arbitrarily changed according to the polymerization temperature, polymerization pressure, charged amount of perfluoro(alkyl vinyl ether), etc.

[0032] In the solution suspension polymerization method, in addition to tetrafluoroethylene, perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether) (hereinafter also referred to as the "three-component monomer mixture") which are the raw materials, a polymerization initiator is used. As the polymerization initiator, a diacyl peroxide type is preferable. Further, a chain transfer agent can be used as needed. Examples of such chain transfer agents include alcohols, hydrocarbons, halogenated hydrocarbons, esters, ketones, etc., and methanol is particularly preferable.

[0033] The copolymerization reaction is preferably carried out under temperature conditions of about 15°C or higher and 80°C or lower and pressure conditions of about 0.3 MPa or higher and 1.0 MPa or lower. In order to maintain such pressure conditions, in addition to the initial charge consisting of the three-component monomer mixture, it is preferable to separately add an additional supply component consisting of the same three-component monomer mixture continuously or intermittently to the pressure-resistant reaction vessel. After the reaction is completed, the unreacted gas is purged from the pressure-resistant reaction vessel, the reaction mixture is withdrawn, and further washed and dried to obtain a predetermined fluorine-containing terpolymer.

[0034] <Method for manufacturing a container> The method for manufacturing a container is not particularly limited. For example, using the above-mentioned fluororesin, it is formed into the desired shape of the container by a molding method such as injection molding, blow molding, injection blow molding, etc. For example, in the injection molding method, after producing a mold (mold frame) having the desired shape of the container, the molten fluororesin is filled into this mold and injection molded to manufacture a container in which the bottom wall, side wall, and opening are integrally formed within the same mold.

[0035] As described above, the embodiments of the present invention have been explained, but the present invention is not limited to the above embodiments, and includes all aspects included in the concept and claims of the present invention, and can be variously modified within the scope of the present invention.

[0036] Based on the above embodiments, the present invention relates to the following [1] to [9]. [1]A fluororesin container comprising a bottom wall, side walls erected around the bottom wall, and an opening defined by upper ends of the side walls, wherein the fluororesin is a fluorine-containing terpolymer, the fluorine-containing terpolymer has a refractive index of 1.32 or more and 1.34 or less, the fluororesin container is characterized in that for a film of the fluorine-containing terpolymer having a thickness of 2 mm, the light transmittance at 650 nm measured using a spectrophotometer is 85% or more. [2]The container according to [1] above, wherein the fluorine-containing terpolymer is a terpolymer of 5% by weight or more and 98% by weight or less of tetrafluoroethylene, 1% by weight or more and 40% by weight or less of perfluoro(ethyl vinyl ether), and 1% by weight or more and 55% by weight or less of perfluoro(propyl vinyl ether). [3]The container according to [1] or [2] above, wherein the fluorine-containing terpolymer has a specific melt viscosity of 0.1×10 3 Pa·s or more and 110×10 3 Pa·s or less at 372°C. [4]The fluororesin container according to any one of [1] to [3] above, wherein the fluororesin container has a petri dish shape. [5]The fluororesin container according to [4] above, wherein a plurality of wells provided in a concave shape on the inner surface of the bottom wall are patterned. [6]The fluororesin container according to any one of [1] to [3] above, wherein the fluororesin container has a frustum of a cone shape. [7]The fluororesin container according to [6] above, wherein the inner surface of the bottom wall is a flat surface. [8]The fluororesin container according to [6] above, wherein the fluororesin container has a U-shaped cross section. [9]The fluororesin container according to any one of [1] to [8] above, wherein the fluororesin container is a container for cell observation.

Examples

[0037] Next, examples of the present invention will be described, but the present invention is not limited to these examples.

[0038] (Synthesis Example 1) Into a 3 L stainless steel autoclave with a stirrer and degassed, 1000 g of demineralized and deoxygenated water, 690 g of perfluoro-n-heptane, 495 g of perfluoro(ethyl vinyl ether) [FEVE], 720 g of perfluoro(propyl vinyl ether) [FPVE], and 0.1 g of methanol were charged respectively. After heating to 30 °C, 260 g of tetrafluoroethylene [TFE] was charged until the pressure reached 0.85 MPa. This initial charge composition was TFE / FEVE / FPVE = 18 / 33 / 49 (wt%).

[0039] Next, 4.0 g of a solution of isobutyryl peroxide (25 wt%) in a fluorinated hydrocarbon (CClF2CF2CHClF) was added to initiate the polymerization reaction. Since the pressure decreased as the reaction proceeded, TFE was additionally supplied to maintain the polymerization pressure. At that time, FEVE and FPVE were additionally supplied according to the total charge amount of TFE, and the additional charge composition ratio was adjusted to be TFE / FEVE / FPVE = 18 / 33 / 49 (wt%).

[0040] When the supply amounts of TFE 300 g, FEVE 550 g, and FPVE 800 g were reached, the supply of TFE was stopped and aging was carried out. When the pressure reached 0.5 MPa, the unreacted gas was purged, and the polymer was taken out from the autoclave. This polymer was dried under reduced pressure, washed with water, and dried to obtain 161 g of a fluorine-containing terpolymer.

[0041] <Refractive index> A film with a thickness of 2 mm was prepared using the fluorine-containing terpolymer prepared in Synthesis Example 1. For the prepared film, using a refractometer (manufactured by Shimadzu Corporation, "KARL FISCHER Precision Refractometer KPR-3000"), the refractive index at a wavelength of 587.6 nm (d-line) was measured by the V-block method (JIS B7071-2:2018 Method for Measuring the Refractive Index of Optical Glass - Part 2: Conforming to the V-block Method). The refractive index was 1.331.

[0042] <Light transmittance> A film with a thickness of 2 mm was prepared using the fluorine-containing terpolymer produced in Synthesis Example 1. For the prepared film, the light transmittance at a wavelength of 650 nm was measured using an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, "V-770"). The light transmittance was 94.2%.

[0043] <Specific melt viscosity> Using a melt indexer (manufactured by Toyo Seiki Seisakusho), the fluorine-containing terpolymer produced in Synthesis Example 1 was placed in a cylinder with an inner diameter of 9.5 mm, kept at a temperature of 372 °C for 5 minutes, and then extruded through an orifice with an inner diameter of 2.095 mm and a length of 8.00 mm under a piston load of 5 Kg. The value obtained by dividing 53150 by the extrusion rate (g / min) was defined as the specific melt viscosity. The specific melt viscosity was 1.3×10 3 Pa·s.

[0044] <Example 1> A petri dish with a flat bottom wall as shown in FIGS. 1 and 2 (outer diameter of the bottom wall: 37 mm, height of the side wall: 12 mm, angle of the side wall with respect to the inner surface of the bottom wall: 91.5°) was injection-molded using the fluorine-containing terpolymer produced in Synthesis Example 1 to produce a fluororesin container. Next, spherical polystyrene beads with a diameter of 20 μm, which are approximately the same size as the average size of human cells (20 μm), and water were added into this petri dish, and observed under an inverted microscope (manufactured by Nikon Corporation, "ECLIPSE Ti2-U") at a magnification of 4 times. As a result, as shown in FIG. 8, the spherical polystyrene beads could be observed without the shape of the container being visually recognized.

[0045] <Example 2> Using a mold with fine recesses provided on the inner surface of the bottom wall of the petri dish prepared in Example 1 in a predetermined pattern, injection molding was performed to produce a petri dish (well opening width: 500 μm, well depth: 200 μm) provided with a plurality of wells as shown in FIGS. 3 and 4. Next, spherical polystyrene beads with a diameter of 20 μm, which are approximately the same size as the average size of human cells (20 μm), and water were individually added into each well, and the sample was observed under a 4-fold magnification with an inverted microscope (manufactured by Nikon Corporation, "ECLIPSE Ti2-U"). As a result, as shown in FIG. 9, the spherical polystyrene beads could be observed without the shape of the container being visually recognized.

[0046] <Comparative Example 1> A petri dish with a plurality of wells provided on the inner surface of the bottom wall was produced in the same manner as in Example 2, except that an acrylic resin (PMMA) was used instead of the fluorine-containing terpolymer produced in Synthesis Example 1. Next, spherical polystyrene beads with a diameter of 20 μm, which are approximately the same size as the average size of human cells (20 μm), and water were individually added into each well, and the sample was observed under a 4-fold magnification with an inverted microscope (manufactured by Nikon Corporation, "ECLIPSE Ti2-U"). As a result, as shown in FIG. 10, the shape of the container was clearly visually recognized, and this visual recognition of the container shape hindered the observation of the spherical polystyrene beads.

[0047] <Example 3> A frustum-shaped container with a U-shaped longitudinal cross-section as shown in FIG. 7 (outer diameter of the bottom wall: 5 mm, height of the side wall: 13 mm) was produced by injection molding using the fluorine-containing terpolymer produced in Synthesis Example 1. Next, spherical polystyrene beads with a diameter of 20 μm, which are approximately the same size as the average size of human cells (20 μm), and water were added into this container, and the sample was observed under a 4-fold magnification with an inverted microscope (manufactured by Nikon Corporation, "ECLIPSE Ti2-U"). As a result, as shown in FIG. 11, the spherical polystyrene beads could be observed without the shape of the container being visually recognized.

[0048] <Comparative Example 2> A frustum-shaped container with a U-shaped longitudinal cross-section was fabricated in the same manner as in Example 3, except that an acrylic resin (PMMA) was used instead of the fluorine-containing terpolymer prepared in Synthesis Example 1. Subsequently, spherical polystyrene beads with a diameter of 20 μm, which are approximately the same size as the average size of human cells (20 μm), and water were added into this container, and the container was observed under an inverted microscope (manufactured by Nikon Corporation, "ECLIPSE Ti2-U") at a magnification of 4 times. As a result, as shown in Fig. 12, the shape of the container was clearly visible, and the visibility of such a container shape hindered the observation of the spherical polystyrene beads.

Explanation of reference signs

[0049] 10 Container, 11 Bottom wall, 12 Side wall, 13 Opening, 14 Well, 14a Opening, 14b Bottom surface, 20 Container, 21 Bottom wall, 21a Flat surface, 21b Central portion, 22 Side wall, 23 Opening

Claims

1. A fluororesin container comprising a bottom wall, side walls erected around the bottom wall, and an opening defined by upper ends of the side walls, wherein the fluororesin is a fluorine-containing terpolymer, the fluorine-containing terpolymer has a refractive index of 1.32 or more and 1.34 or less, and for a film having a thickness of 2 mm of the fluorine-containing terpolymer, the light transmittance at 650 nm measured using a spectrophotometer is 85% or more. The fluororesin container is characterized by this.

2. The container according to claim 1, wherein the fluorine-containing terpolymer is a terpolymer of 5% by weight or more and 98% by weight or less of tetrafluoroethylene, 1% by weight or more and 40% by weight or less of perfluoro(ethyl vinyl ether), and 1% by weight or more and 55% by weight or less of perfluoro(propyl vinyl ether).

3. The fluorine-containing terpolymer has a specific melt viscosity of 0.1×10 ３ Pa·s or more and 110×10 ３ Pa·s or less at 372°C. The container according to claim 1 is characterized by this.

4. The fluororesin container according to claim 1 or 2, wherein the fluororesin container has a petri dish shape.

5. The fluororesin container according to claim 4, wherein a plurality of wells provided in a concave shape on an inner surface of the bottom wall are patterned.

6. The fluororesin container according to claim 1 or 2, wherein the fluororesin container has a frustum of a cone shape.

7. The fluororesin container according to claim 6, wherein an inner surface of the bottom wall is a flat surface.

8. The fluororesin container according to claim 6, wherein the fluororesin container has a U-shaped cross section.

9. The fluororesin container according to claim 1 or 2, wherein the fluororesin container is a container for cell observation.

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