Microchannel device and method for producing same

Abstract

To provide a micro flow channel device which is excellent in resistance against bending, and suppresses lowering of inspection accuracy.SOLUTION: A micro flow channel device has a flow channel sandwiched between flow channel walls formed inside a porous base material, wherein the flow channel wall contains a thermoplastic resin and a wax, and a ratio of the wax in an area on a surface side opposite to the flow channel of the flow channel wall is higher than a ratio of the wax inside the flow channel wall.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a microchannel device having a microchannel formed inside a porous substrate, and a method for producing the same. [Background technology]

[0002] In recent years, the development of micro-channel devices that can perform biochemical analysis efficiently (micro-amount, rapid, simple) within one chip using micro-sized fine channels has attracted attention in a wide range of fields. Specifically, they have attracted attention in various fields such as medical care, drug discovery, healthcare, the environment, and food, as well as biochemical research. Among them, paper-based paper microanalysis chips have the advantages of being lighter and less expensive than conventional devices, not requiring a power source, and being easily disposable. For this reason, they are expected to be used in medical activities in developing countries and remote areas where medical facilities are not well-equipped, as well as at disaster sites, and as testing devices at airports where the spread of infectious diseases must be stopped at the border. In addition, because they are inexpensive and easy to handle, they are attracting attention as healthcare devices that can manage and monitor one's own health condition.

[0003] In the early 1990s, photolithography and molds were used to form micron-sized fine flow channels on glass or silicon, and microanalysis chips were developed that could perform sample pretreatment, stirring, mixing, reaction, and detection on a single chip. As a result, it was possible to miniaturize the testing system, perform rapid analysis, and reduce the amount of specimens, reagents, and waste liquid. However, while the microchannels created using these photolithography techniques have extremely high precision, their manufacturing costs are very high and they are difficult to incinerate, making them difficult to dispose of. In addition, because additional equipment such as a syringe pump is required to send the test liquid into the channel, their use is limited to environments with well-equipped facilities, and they have been used mainly in biochemistry research institutions.

[0004] In response to these issues, paper microanalysis chips use inexpensive materials such as paper and cloth as a base material, and by utilizing the capillary action of the material itself, they can drive specimens and test solutions, making them low-cost and usable in non-electric environments. They are also easy to carry (distribute) and dispose of (just burn them). Furthermore, since no maintenance is required for the device, anyone (even ignorant elderly people and children) can easily perform point-of-care (POC) diagnosis at low cost anywhere (even in places without power). Therefore, research and development of paper microchannel devices for various infectious diseases, specific diseases, and healthcare (chronic disease management, health management) is currently being conducted at research institutes around the world.

[0005] Since microfluidic devices use liquids as specimens or test solutions, the materials that form the channels are required to have high hydrophobicity to prevent the liquid from seeping into the channel walls and to prevent the channel walls from swelling due to water absorption when the device is used in a high humidity environment. In particular, the hydrophobicity of the side surface of the channel wall on the channel side is important, and has a large effect on the flow rate of the specimen and the seepage onto the channel wall.

[0006] Patent Document 1 proposes a microchannel device in which channel walls are formed in a porous substrate (such as paper) using a thermal transfer printer. In this proposal, channel walls are formed by filling pores in the porous substrate with a molten channel wall-forming material through thermocompression bonding. Thermoplastic materials and oils and fats (wax) are used as the channel wall-forming material.

[0007] However, Patent Document 1 only discloses that wax is present evenly inside the channel wall. When the amount of wax inside the channel wall is increased, the hydrophobicity of the channel wall is sufficient, but the flexibility of the channel wall is lost and the resistance to bending and the like is reduced. Conversely, when the amount of wax inside the channel wall is decreased, the channel wall has good flexibility, so the resistance to bending and the like is good, but the hydrophobicity of the channel wall tends to be insufficient. Therefore, when the amount of wax inside the channel wall is made uniform, it is difficult to achieve both hydrophobicity and resistance to bending and the like. In addition, when the hydrophobicity of the channel wall is insufficient, there is a risk that the sample liquid will seep out of the channel, or turbulence will occur in the sample liquid, which may cause a decrease in sensitivity due to a decrease in flow rate. Based on these considerations, the present invention proposes a microchannel device that forms flow channel walls that have excellent resistance to bending and maintain high hydrophobicity, thereby suppressing loss of sensitivity that occurs when a sample or test solution flowing through the flow channel seeps out of the flow channel walls or when the flow rate changes. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2015-131257 A Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a microchannel device that has excellent resistance to bending and in which a decrease in inspection accuracy is suppressed. [Means for solving the problem]

[0010] A microchannel device having a channel sandwiched between channel walls formed inside a porous substrate, the flow path wall contains a thermoplastic resin and a wax; The flow path wall has a higher wax content in a region on a surface side thereof facing the flow path than in an interior portion of the flow path wall. Effect of the Invention

[0011] According to the present invention, it is possible to provide a microchannel device that has excellent resistance to bending and in which a decrease in inspection accuracy is suppressed. [Brief description of the drawings]

[0012] [Figure 1] 3 is a cross-sectional view of a microchannel device formed by permeating a channel wall-forming material T1 into a porous substrate S1 in Example 1. FIG. [Diagram 2] FIG. 2 is a configuration diagram of an image forming unit 100 according to the first embodiment. [Diagram 3] FIG. 2 is a configuration diagram of a process cartridge P according to the first embodiment. [Figure 4] 2 is a block diagram showing a schematic control mode of the image forming unit 100 according to the first embodiment. FIG. [Diagram 5] FIG. 2 is a flow path pattern diagram in the first embodiment. [Figure 6] FIG. 3 is a cross-sectional view of a flow path wall in the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is merely an example, and the present invention is not limited to the contents of the embodiment. In addition, in each of the following drawings, components that are not necessary for the description of the embodiment are omitted from the drawings. In the microchannel device according to the present invention, a channel sandwiched between channel walls is formed inside a porous substrate. The channel walls include a thermoplastic resin and a wax. The proportion of the wax is higher in the region of the surface of the flow path wall facing the flow path than in the interior of the flow path wall.

[0014] The "proportion of wax" refers to the proportion of the area occupied by wax when observing the cross section of the microchannel device. The term "surface of the flow path wall facing the flow path" refers to the surface of the flow path wall facing the flow path and present inside the substrate. By "inside the flow channel wall" is meant the inside of the flow channel wall that is not the surface of the porous substrate and that does not face the flow channel. When measuring the "proportion of wax", a cross section is created that crosses the flow path and the flow path wall. When measuring the proportion of wax on the "side of the flow path wall facing the flow path", the proportion of wax is measured on the side of the flow path wall facing the flow path as close to the flow path as possible. When measuring the proportion of wax inside the flow path wall, the proportion of wax is measured in a portion of the flow path wall that is sufficiently separated from the side of the flow path wall facing the flow path and also separated from the surface of the substrate.

[0015] The phrase "the proportion of wax in the region of the flow path wall facing the flow path is higher than the proportion of wax inside the flow path wall" means that when the proportion of wax in the flow path wall material inside the flow path wall is X and the proportion of wax in the flow path wall material in the region of the flow path wall facing the flow path is Y, Y>X. Based on the area originating from the channel wall material observed in the cross section of the microchannel device, X is preferably 3 to 20%, more preferably 5 to 15%, and Y is preferably 25 to 95%, more preferably 27 to 88%. In this case, both bending resistance and high inspection accuracy are more satisfactorily achieved.

[0016] The microchannel device of the present invention can be manufactured, for example, by an electrophotographic method through the following steps. (i) A latent image corresponding to a flow path pattern to be formed is formed on a photoreceptor, and the latent image is developed using particles of a flow path wall forming material. (ii) The developed image is transferred to the surface of the porous substrate to form a channel pattern on the porous substrate. (ii) The flow path pattern formed on the porous substrate is melted by heat to penetrate into the interior of the porous substrate, thereby forming flow path walls inside the porous substrate.

[0017] <Flow channel wall forming material> The flow path wall forming material contains a thermoplastic resin and wax (oil and fat). A flow path pattern is formed on the surface of the porous substrate using a flow path wall forming material, and the flow path pattern is melted by heat to cause the flow path wall forming material to penetrate into the interior of the porous substrate, thereby forming flow path walls.

[0018] -Thermoplastic resin- The thermoplastic resin is not particularly limited, but is preferably an amorphous resin. For example, the following known thermoplastic resins can be used: polyester resin, vinyl resin, acrylic resin, styrene-acrylic resin, polyethylene, polypropylene, polyolefin, ethylene-vinyl acetate copolymer resin, ethylene-acrylic acid copolymer resin, etc. Among the thermoplastic resins, polyester resins or styrene-acrylic resins are preferred, and styrene-acrylic resins are more preferred.

[0019] As the polyester resin, known polyester resins can be used. Specific examples of methods for producing polyester resins include the following: A method in which a dibasic acid or a derivative thereof and a dihydric alcohol are essential, and, as necessary, a trivalent or higher polybasic acid and its derivatives (carboxylic acid halides, esters, acid anhydrides), a monobasic acid, a trivalent or higher alcohol, a monohydric alcohol, etc. are subjected to dehydration condensation.

[0020] Examples of dibasic acids include the following: aliphatic dibasic acids such as maleic acid, fumaric acid, itaconic acid, oxalic acid, malonic acid, succinic acid, dodecylsuccinic acid, dodecenylsuccinic acid, adipic acid, azelaic acid, sebacic acid, and decane-1,10-dicarboxylic acid; aromatic dibasic acids such as phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, tetrabromophthalic acid, tetrachlorophthalic acid, HET acid, himic acid, isophthalic acid, terephthalic acid, and 2,6-naphthalenedicarboxylic acid; and the like. Furthermore, examples of derivatives of dibasic acids include carboxylic acid halides, esters and acid anhydrides of the above aliphatic dibasic acids and aromatic dibasic acids.

[0021] On the other hand, examples of dihydric alcohols include the following: acyclic aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and neopentyl glycol; bisphenols such as bisphenol A and bisphenol F; alkylene oxide adducts of bisphenol A such as an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A; aralkylene glycols such as xylylenediglycol; and the like. Examples of trivalent or higher polybasic acids and anhydrides thereof include trimellitic acid, trimellitic anhydride, pyromellitic acid, and pyromellitic anhydride.

[0022] Examples of polymerizable monomers capable of forming the styrene-acrylic resin include the following: styrene-based monomers such as styrene, α-methylstyrene, and divinylbenzene; unsaturated carboxylic acid esters such as methyl acrylate, butyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, t-butyl methacrylate, and 2-ethylhexyl methacrylate; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; unsaturated dicarboxylic acids such as maleic acid; unsaturated dicarboxylic anhydrides such as maleic anhydride; nitrile-based vinyl monomers such as acrylonitrile; halogen-containing vinyl monomers such as vinyl chloride; nitro-based vinyl monomers such as nitrostyrene; and the like. These may be used alone or in combination.

[0023] When forming a copolymer of the styrene-based polymerizable monomer and an acrylic acid ester or a methacrylic acid ester, a crosslinking agent may be added to the styrene-acrylic resin, if necessary. For example, the following may be mentioned. Divinylbenzene, bis(4-acryloxypolyethoxyphenyl)propane, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol #200 diacrylate (CH2=CHC(=O)O(CH2CH2O)4C(=O)CH=CH2, molecular weight 308), polyethylene glycol #400 diacrylate (CH2=CHC(=O)O(CH2CH2O)9C(=O)CH=CH2, molecular weight 508), polyethylene glycol #600 diacrylate (CH2=CHC(=O)O(CH2CH2O) 14 C(=O)CH=CH2, molecular weight 708), dipropylene glycol diacrylate, polypropylene glycol diacrylate, polyester diacrylate (MANDA Nippon Kayaku), and the above acrylates replaced with methacrylates.

[0024] Examples of trifunctional or higher crosslinkable monomers include the following: pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate and its methacrylate, 2,2-bis(4-methacryloxy-polyethoxyphenyl)propane, diacryl phthalate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, and diaryl chlorendate.

[0025] The weight average molecular weight (Mw) of the thermoplastic resin is preferably in the range of 3,000 or more and 500,000 or less, more preferably 5,000 or more and 300,000 or less, and further preferably 7,500 or more and 100,000 or less.

[0026] -Wax (oils and fats)- The material used as the wax in the present invention is not particularly limited, and any of the known waxes used in toners such as those described below can be used.

[0027] Esters of monohydric alcohols and aliphatic carboxylic acids, such as behenyl behenate, stearyl stearate, and palmityl palmitate; esters of dihydric alcohols and aliphatic carboxylic acids, such as ethylene glycol dibehenate and hexanediol dibehenate; esters of dihydric alcohols and aliphatic carboxylic acids, such as dibehenyl sebacate; esters of trihydric alcohols and aliphatic carboxylic acids, such as glycerin tribehenate; esters of tetrahydric alcohols and aliphatic carboxylic acids, such as pentaerythritol tetrastearate and pentaerythritol tetrapalmitate; esters of tetrahydric alcohols and aliphatic carboxylic acids, such as dipentaerythritol dimer; Esters of hexahydric alcohols and aliphatic carboxylic acids, such as dipentaerythritol hexastearate and dipentaerythritol hexapalmitate, or esters of hexahydric carboxylic acids and aliphatic alcohols; esters of polyhydric alcohols and aliphatic carboxylic acids, such as polyglycerol behenate, or esters of polyhydric carboxylic acids and aliphatic alcohols; natural ester waxes, such as carnauba wax and rice wax; hydrocarbon waxes (petroleum waxes and derivatives thereof, such as paraffin wax, microcrystalline wax, and petrolatum; waxes and derivatives thereof produced by the Fischer-Tropsch process; polyolefin waxes and derivatives thereof, such as polyethylene wax and polypropylene wax); higher aliphatic alcohols; fatty acids, such as stearic acid and palmitic acid; acid amide waxes. These waxes may be used alone or in combination.

[0028] Among these, preferred are ester compounds of a diol having 2 to 6 carbon atoms and an aliphatic monocarboxylic acid having 14 to 22 carbon atoms, and more preferred are ester compounds of a diol having 2 carbon atoms and an aliphatic monocarboxylic acid having 14 to 22 carbon atoms. Hydrocarbon waxes are also preferred waxes.

[0029] The content of the wax in the flow path wall forming material is preferably 1.0% by mass or more and 25.0% by mass or less, and more preferably 3.0% by mass or more and 20.0% by mass or less. By being in the above range, it is possible to achieve both excellent low-temperature fixability and excellent heat-resistant storage stability. A more preferred range is 5.0% by mass or more and 15.0% by mass or less. The weight average molecular weight of the wax is preferably 300 or more and 10,000 or less. If the weight average molecular weight of the wax is less than 300, the wax will have too high permeability, which may result in increased seepage from the surface side of the flow path wall, resulting in the formation of a flow path wall on the inside of the flow path, which may narrow the flow path itself. If the weight average molecular weight of the wax exceeds 10,000, the wax tends to remain inside the flow path wall forming material, and there is a possibility that the wax does not come out to the surface side of the flow path wall facing the flow path.

[0030] <How to calculate solubility parameter (SP value)> The solubility parameter (SP value) is calculated using Fedors' equation (2). The values ​​of Δei and Δvi below are based on the evaporation energies and molar volumes (25° C.) of atoms and atomic groups listed in Table 3-9 of "Basic Science of Coatings," pp. 54-57, 1986 (Maki Shoten Publishing). The unit of SP value is (cal / cm 3 ) 1 / 2 However, 1 (cal / cm 3 ) 1 / 2 =2.046×10 3 (J / m 3 ) 1 / 2 by (J / m 3 ) 1 / 2 can be converted to units of δi=(Ev / V) 1 / 2 =(Δei / Δvi) 1 / 2 Formula (2) Ev: Evaporation energy V: Molar volume Δei: Evaporation energy of the atom or atomic group of the i component Δvi: Molar volume of the atom or atomic group of the i component

[0031] The SP value of the wax is preferably lower than the SP value of the thermoplastic resin. The SP value of the wax is SP(W)(cal / cm 3 ) 1 / 2 The SP value of the thermoplastic resin is SP(B) (cal / cm 3 ) 1 / 2 When set to , it is preferable that the following formula (1) is satisfied. SP(B)-SP(W)≧0.5 (1) If the difference between the SP value of the resin and the SP value of the wax is 0.5 or less, the resin and the wax will be compatible with each other, and the amount of wax on the surface of the flow channel wall facing the flow channel will be insufficient, which may result in insufficient hydrophobicity of the flow channel wall, which may cause the sample to bleed out of the flow channel when it is dropped.

[0032] <Method of measuring molecular weight distribution and peak molecular weight> The molecular weight distribution and the peak molecular weight are measured by gel permeation chromatography (GPC) as follows. First, the measurement sample is dissolved in tetrahydrofuran (THF). The obtained solution is then filtered through a solvent-resistant membrane filter "Myshoridisc" (manufactured by Tosoh Corporation) with a pore size of 0.2 μm to obtain a sample solution. The sample solution is adjusted so that the concentration of components soluble in THF is 0.8 mass%. This sample solution is used to perform measurements under the following conditions. Equipment: High-speed GPC equipment "HLC-8220GPC" [Tosoh Corporation] Column: 2 columns of LF-604 [Showa Denko Co., Ltd.] Eluent:THF Flow rate: 0.6mL / min Oven temperature: 40℃ Sample injection volume: 0.020mL

[0033] The molecular weight of the sample was calculated using a molecular weight calibration curve prepared using the following standard polystyrene resin. The largest peak in the obtained molecular weight distribution was taken as the main peak, and the molecular weight of the peak was taken as the peak molecular weight. Standard polystyrene resin: Product name "TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500" manufactured by Tosoh Corporation

[0034] <Image (flow path pattern) forming unit> The overall configuration of the image forming unit will be described with reference to FIGS. 2, 3 and 4. FIG. FIG. 2 is a cross-sectional view showing the schematic configuration of an image forming unit 100 according to an embodiment of the present invention, and each component is shown in a simplified manner. FIG. 3 is a schematic cross-sectional view of a process cartridge P according to an embodiment of the present invention. FIG. 4 is a block diagram showing an outline of the control mode of the main parts of the image forming unit 100 in this embodiment.

[0035] First, the configuration of the image forming unit, the image forming process, and each member will be described. Each member involved in the image forming process will be described in the order of the image forming process with reference to FIG.

[0036] The image forming unit 100 accommodates a process cartridge P. The process cartridge P includes a photosensitive drum 11 as an image carrier. Around the photosensitive drum 11, there are provided a charging roller 12 for charging the surface of the photosensitive drum 11, a developing device 20 for developing an electrostatic latent image formed on the surface of the photosensitive drum 11 with a developer (particles for forming flow path walls), and a cleaning member 14 for cleaning the surface of the photosensitive drum 11. The developing device 20 has a developer container 21 and a developing blade 25. Voltages required for image formation can be applied by a charging high-voltage power supply 71, a developing high-voltage power supply 72, and a transfer high-voltage power supply 74, and are controlled by a control unit 202 (FIG. 4).

[0037] When image formation begins, a voltage of -946V is applied to the charging roller 12 as charging for image formation, so that the surface of the photosensitive drum 11 is uniformly charged to -460V. A DC (direct current) voltage is applied to the charging roller 12, and the surface of the photosensitive drum 11 is uniformly charged to a charging potential Vd by discharge. Vd at this time is called the dark potential, and is -460V.

[0038] After the surface of the photosensitive drum 11 is charged by the charging roller 12, the surface of the photosensitive drum 11 is irradiated with a laser beam 9 from an exposure unit 73. The surface potential of the surface of the photosensitive drum 11 irradiated with the laser beam 9 changes to −100 V as a bright area potential Vl, and an electrostatic latent image is formed. As shown in FIG. 4, the exposure unit 73 receives a time-series electric digital pixel signal of image information that has been input from a controller 200 via an interface 201 to a control section 202 and has been image-processed. The exposure unit 73 has a laser output section that outputs laser light 9 modulated in response to an input time-series electric digital pixel signal, a rotating polygon mirror, an fθ lens, a reflecting mirror, etc., and performs main scanning exposure on the surface of the photosensitive drum 11 with the laser light 9. By this main scanning exposure and sub-scanning due to the rotation of the photosensitive drum 11, an electrostatic latent image corresponding to the image information is formed.

[0039] <Image (flow path pattern) formation process> The image forming unit 100 has a contact / separation means 75 for controlling the position of the developing device 20, and can control the position of the developing device 20 to be different during image formation and during non-image formation. The operation of the contact / separation means 75 is controlled by the control unit 202 shown in FIG. In the developing device 20 , after the photosensitive drum 11 starts to rotate, the developing roller 23 as a developer carrier that was separated from the photosensitive drum 11 is moved by the contact / separation means 75 so as to come into contact with the photosensitive drum 11 .

[0040] Next, the developing roller 23 starts to rotate in the direction of the arrow C in FIG. 3, and the supply roller 24 as a supply member of the developer (particles for forming the flow path wall) starts to rotate in the direction of the arrow D in FIG. 3 by driving the motor M2 (not shown) connected to each of them. Then, a voltage of −300V is applied as a developing voltage from the developing high voltage 72 for the developing roller 23 to the developing roller 23, and the electrostatic latent image formed on the photosensitive drum 11, that is, the above-mentioned Vl portion, is supplied with the developer by the developing roller 23 and developed. Note that the ratio of the moving speed of the surface of the photosensitive drum 11 to the moving speed of the surface of the developing roller 23 at this time (moving speed of the surface of the developing roller 23 / moving speed of the surface of the photosensitive drum 11) is called the developing peripheral speed ratio. By controlling this developing peripheral speed ratio, the amount of developer developed on the photosensitive drum 11 can be controlled. For example, if the developing peripheral speed ratio is 2.5, when all the developer on the developing roller 23 is used to develop the electrostatic latent image on the photosensitive drum 11, the amount of developer per unit area on the surface of the photosensitive drum 11 will be 2.5 times the amount of developer per unit area on the surface of the developing roller 23. In the examples described later, the developing peripheral speed ratio was controlled so that an amount of developer suitable for forming a flow path wall inside the porous substrate S1 could be developed.

[0041] The porous substrate S1 is placed on the paper feed tray 1 and is picked up one by one by the pickup roller 2. The developed developer image (flow path pattern) is transferred to the porous substrate S1 by the potential difference with the transfer roller 4 to which +2000V is applied by the transfer high voltage 74. The transfer roller 4 uses a conductive shaft body (hereinafter also referred to as a core metal) and a semiconductive sponge whose main component is NBR hydrin rubber, which is an elastic body, for the part pressed against the photosensitive drum 11, and resistance is adjusted using an ion conductive material. It has an outer diameter of φ12.5 mm and a core metal diameter of φ6 mm.

[0042] The porous substrate S1 onto which the developer image has been transferred is discharged to the outside of the image forming unit with the developer image facing upward in the direction of gravity. After the photosensitive drum 11 has passed the transfer roller 4, the cleaning member 14 in contact with the photosensitive drum 11 scrapes off any developer that has not been transferred. A series of processes starting from charging by the charging roller 12 is repeated to continuously form images.

[0043] <Heating process> The porous substrate S1 to which the flow path pattern has been transferred undergoes a heating process by a heating unit (not shown). Through the heating process, the flow path wall forming material melts and permeates into the porous substrate S1, forming hydrophobic flow path walls. Therefore, the heating temperature must be such that the flow path wall-forming material melts and permeates into the porous substrate S1. In the configuration of the example described below, the flow path wall-forming material permeated into the porous substrate S1 at 140°C or higher.

[0044] The heating time is required to be long enough for the molten flow path wall forming material to completely permeate in the thickness direction of the porous substrate S1, but if the heating time is too long, the material will diffuse more than necessary, and the flow paths 82 after the heating process may become thinner than the flow path pattern formed by printing. In the configuration of this embodiment, a heating time of 1 to 10 minutes allowed the formation of appropriate flow path walls.

[0045] In view of the above, the heating conditions in the examples described below were set to 2 minutes in an environment of 200° C. An oven (Yamato Scientific Co., Ltd., constant temperature incubator with air blower, DN610H) was used as the heating unit. However, the heating method is not limited to this, and a far-infrared heater, a hot plate, etc. may also be used, and the heating conditions should be selected according to the physical properties of the flow path wall forming material and the porous substrate S1.

[0046] The heating process under the above conditions will be explained with reference to Figs. 1(a) and 1(b). As a diagram showing the flow path wall forming material before and after heating, a cross-sectional schematic diagram at the position of dashed line 80a in Fig. 5 is shown in Fig. 1. Fig. 1(a) is a cross-sectional view before heating, Fig. 1(b) is a cross-sectional view after heating, and Fig. 1(c) is an enlarged view of a part of Fig. 1(b). Before heating, the flow channel wall-forming material is merely attached to the surface of the porous substrate S1, as shown in Fig. 1(a). Subsequent heating melts the flow channel wall-forming material, and it permeates into the porous substrate S1 due to capillary action with the porous substrate S1, forming flow channel walls, as shown in Fig. 1(b) and Fig. 1(c). In this way, a microflow channel device having a flow channel 82 sandwiched between flow channel walls is obtained in the porous substrate.

[0047] <Flow path> The channel is a region of the porous substrate sandwiched between channel walls (described in more detail below), through which sample liquid flows by capillary action. In the examples described later, a flow path pattern 80 shown in FIG. 5(a) was formed on a porous substrate S1 using a flow path pattern image forming unit 100. Fig. 5(b) is a schematic cross-sectional view taken along dashed line 80a in Fig. 5(a), and Fig. 5(c) is an enlarged view of a portion of Fig. 5(b).

[0048] In using the device as a microchannel device, a particle portion 81 for forming a channel wall was formed to surround the reagent portion 83, the test liquid portion 84, and the channel 82. The reagent portion 83 is for attaching a reagent, the test liquid portion 84 is for attaching a test liquid (sample liquid), and the channel 82 connects the reagent portion 83 and the test liquid portion 84. The width L1 of the particle portion 81 for forming a channel wall at the portion sandwiching the channel 82 was set to 4 mm, and the width L2 of the channel 82 was set to 1.5 mm. The diameter L3 of the test liquid portion 84 was set to 7 mm, and the longest portion L4 of the channel was set to 40 mm. As an example of use as a microchannel device, for example, a chemical that shows a color reaction is attached to the reagent portion 83, and then the test liquid is attached to the test liquid portion 84, so that it is possible to check whether the test liquid diffuses through the channel 82 to the reagent portion 83 and whether a color reaction occurs. However, the shape and size of the channel pattern are not limited to those described above, and a shape using a combination of straight lines and curves or a branch may be used, and the width of the channel may be changed midway through the channel.

[0049] <Channel wall> The flow channel wall is made of the flow channel wall-forming material and has high hydrophobicity. In particular, in order to function as a flow channel, it is important that the surface (side surface) of the flow channel wall facing the flow channel has high hydrophobicity. By increasing the hydrophobicity, the flow rate of the sample can be increased and bleeding onto the flow channel wall can be suppressed. In order to increase the hydrophobicity of the surface of the flow channel wall facing the flow channel, it is effective to increase the proportion of wax in that portion.

[0050] When forming a flow channel pattern on the surface of the porous substrate, a developer (particles for forming flow channel walls) with different amounts of wax can be used in the area facing the flow channel and the area inside the flow channel wall. Specifically, a developer with a large amount of wax is used as a developer for forming the area facing the flow channel (for example, about 1 mm wide), and a developer with a small amount of wax or no wax is used as a developer for forming the area inside the flow channel wall. When a flow channel wall is formed using such a flow channel pattern, the amount of wax on the surface of the micro flow channel device and its vicinity can be reduced while ensuring sufficient hydrophobicity on the surface of the flow channel wall facing the flow channel. Other layers or members such as a protective layer or an electrode may be overlaid on the surface of the micro flow channel device, and by reducing the amount of wax on the surface and its vicinity, peeling of the overlaid members can be suppressed. That is, the wax ratio in the region of the flow path wall facing the flow path is preferably higher than the wax ratio in region X (the region of the flow path wall not facing the flow path, and the surface of the porous substrate and its vicinity) that satisfies the following criteria: Furthermore, the wax ratio in region X is more preferably 15% or less, and particularly preferably 8% or less.

[0051] <Porous base material> The porous substrate S1 is preferably one that exhibits moderate porosity and hydrophilicity. The porous structure is preferably one that has an open cell or mesh (nanofiber, etc.) structure, and examples of such materials include filter paper, plain paper, wood-free paper, watercolor paper, Kent paper, synthetic paper, synthetic resin porous film, fabric, and textile products. Among these, filter paper is preferred because of its high porosity and good hydrophilicity. The porosity can be appropriately selected depending on the purpose, but is preferably 20% to 90%. If the porosity exceeds 90%, the strength required as a base material may not be maintained, and if it is less than 20%, the permeability of the sample liquid may be reduced.

[0052] Hydrophilicity is a necessary property for allowing a biological fluid containing water, such as blood, urine, or saliva, as a sample liquid, to diffuse into the substrate. The average thickness of the porous substrate is often 0.01 mm to 0.3 mm. If the average thickness is less than 0.01 mm, the substrate may not be strong enough. Depending on the application, a substrate with a thickness of about 0.6 mm may be used, but the present invention is also suitable for such a case because the flow path wall is formed in a thick porous substrate. Therefore, the average thickness of the porous substrate used in the present invention is preferably 0.01 to 1.0 mm. Apparent density (g / cm 3 ) is the basis weight (g / m 2 ) / thickness (mm)×1000), and porosity (%) was calculated as ((true density−apparent density) / true density×100). Table 1 shows the basis weight and other properties of the porous substrate S1 used in the examples described later.

[0053] [Table 1]

[0054] <Cross section of channel wall> The flow path wall forming material contains a thermoplastic resin and a wax. In the present embodiment, the flow path wall forming material is melted by heat in the heating process as described above, and is permeated into the porous substrate S1 to form a flow path wall in the porous substrate S1. In the configuration of the embodiment described later, the wax W comes out to the outside of the flow path wall as shown in FIG. 1(c). This is because, due to the difference in surface free energy between the thermoplastic resin B and the wax W, the wax W, which has a lower SP value, is more likely to be present in the region of the surface side of the flow path wall on the flow path 82 side facing the flow path.

[0055] In addition, the wax W has a higher permeation rate in the capillary phenomenon in the porous substrate, and therefore is more likely to cover the outside of the flow path wall. Therefore, as shown in Fig. 1(c), the wax W is present in a larger proportion on the side of the flow path 82. This improves the hydrophobicity of the flow path wall, and reduces the risk of liquid such as a sample seeping out of the flow path 82 (inside the flow path wall). Furthermore, the greater the difference between the SP value of the resin and the SP value of the wax, the more easily the wax will reach the surface side (outer edge) of the flow path wall that faces the flow path. EXAMPLES

[0056] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the text, "parts" and "%" are based on mass unless otherwise specified.

[0057] <Example 1> In Example 1, a microchannel device was produced under the above-mentioned conditions using flow channel wall forming particles T1 containing a thermoplastic resin B1 (amorphous resin) and a wax W1. The flow path wall forming particles T1 were produced by suspension polymerization as follows.

[0058] [Preparation of polymerizable monomer composition] Styrene 70.0 parts by mass n-Butyl acrylate 30.0 parts by mass Divinylbenzene 0.3 parts by mass Wax W1 (ethylene glycol dibehenate) 12.0 parts by mass The above materials were kept at 65° C. and were uniformly dissolved and dispersed at 500 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to prepare a polymerizable monomer composition.

[0059] [Preparation of Dispersion Stabilizer] In a 2 L four-neck flask equipped with a high-speed stirring device TK Homomixer (manufactured by Primix Corporation), 710 parts of ion-exchanged water and 450 parts of 0.1 mol / L-sodium phosphate aqueous solution were added, and the mixture was heated to 60° C. while being stirred at a rotation speed of 12,000 rpm. 68.0 parts of 1.0 mol / L-calcium chloride aqueous solution was added thereto to prepare an aqueous dispersion medium containing a poorly water-soluble dispersion stabilizer (calcium phosphate).

[0060] [Granulation / Polymerization] The polymerizable monomer composition was added to the aqueous dispersion medium, and granulated for 15 minutes while maintaining the rotation speed at 12000 rpm. After that, the agitator was replaced from the high-speed agitator to a propeller agitator, and the internal temperature was raised to 60°C and maintained at 60°C to continue the polymerization reaction for 5 hours. The internal temperature was further raised to 80°C and maintained at 80°C to continue the polymerization reaction for 3 hours. After the polymerization reaction was completed, the remaining monomer was distilled off under reduced pressure at 80°C, and then cooled to 30°C to obtain a polymer microparticle dispersion.

[0061] [Cleaning] The polymer microparticle dispersion was transferred to a washing container, and diluted hydrochloric acid was added while stirring to adjust the pH to 1.5. The dispersion was stirred for 2 hours, and then subjected to solid-liquid separation with a filter to obtain polymer microparticles. This was added to 1200 parts of ion-exchanged water and stirred, and the dispersion was made again, and then subjected to solid-liquid separation with a filter. This operation was repeated three times to obtain base particles for flow path wall forming particles T1.

[0062] [External addition of flow improver] 100.0 parts of the obtained base particles were dry-mixed with 1.0 part of a flowability improver (silica having a number-average particle diameter of primary particles of 7 nm) that had been surface-treated with hexamethyldisilazane for 5 minutes in a Henschel mixer to obtain flow path wall forming particles T1 having a weight-average particle diameter (D4) of 6.8 μm.

[0063] <Example 2> In Example 2, a microchannel device was produced in the same manner as in Example 1, except that flow channel wall forming particles T2 were used. The flow path wall forming particles T2 were produced by a pulverization method (production by kneading and pulverizing materials) using the following thermoplastic resin B2 and wax W2. The weight average particle size was 7.0 μm. Thermoplastic resin B2 (amorphous resin): 100 parts by mass of a polyester resin synthesized using a bisphenol A-PO 2-mol adduct and a bisphenol A-EO 2-mol adduct as diol components and terephthalic acid as a dicarboxylic acid component. Wax W2 (Nippon Seiro Hydrocarbon Wax "FNP90") 10 parts by weight

[0064] The manufacturing conditions for the pulverization method are as follows. The above thermoplastic resin B2 and wax W2 were kneaded at 120°C using a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation) to obtain a kneaded product. The kneaded product obtained was cooled and coarsely pulverized to 1 mm or less using a hammer mill to obtain a coarsely pulverized product. The coarsely pulverized product obtained was finely pulverized using a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.). Furthermore, a rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) was used to pulverize the product at a classifying rotor rotation speed of 50.0 s. -1 The particles were classified under the above classification conditions to obtain flow path wall forming particles T2.

[0065] <Example 3> In Example 3, a microchannel device was produced in the same manner as in Example 1, except that flow channel wall forming particles T3 were used. The flow path wall forming particles T3 were produced in the same manner as the flow path wall forming particles T2, except that wax W3 (HNP9: Nippon Seiro, paraffin wax) was used instead of wax W2. The resulting flow path wall forming particles T3 had a weight average particle size (D4) of 7.1 μm.

[0066] <Comparative Example 1> In Comparative Example 1, a microchannel device was produced in the same manner as in Example 1, except that channel wall forming particles T4 were used. Flow path wall forming particles T4 were produced in the same manner as flow path wall forming particles T1, except that wax W1 was not used. The weight average particle size (D4) of the obtained flow path wall forming particles T4 was 7.2 μm. Table 2A shows the types and SP values ​​of the resins, the types, SP values ​​and weight average molecular weights of the waxes, and ΔSP values ​​used in Examples 1 to 3 and Comparative Example 1. Table 2B shows the proportions of the waxes in the microchannel devices produced in Examples 1 to 3 and Comparative Example 1.

[0067] [Table 2A] The units of SP values ​​in Table 2A are (cal / cm 3 ) 1 / 2 It is.

[0068] [Table 2B]

[0069] <Performance evaluation of microfluidic devices> To evaluate the performance of the microchannel devices fabricated using the channel wall forming materials of Examples 1 to 3 and Comparative Example 1, 0.05 mL of water was dropped onto the reagent portion 83 shown in Fig. 5, and the time until the water permeated the entire channel was measured. The shorter the time, the more smoothly the liquid can move due to the suppression of liquid leakage when the test liquid or the like is injected and the improvement of the water repellency of the channel wall surface in the channel. Table 3 shows the results of the permeation time for the microchannel devices of Examples 1 to 3 and Comparative Example 1.

[0070] [Table 3]

[0071] As shown in Table 3, it took 290 seconds for the microchannel device fabricated using the channel wall forming material of Comparative Example 1, which did not contain a wax component, to completely fill the channel with water. In addition, when the channel wall surface after filling with water was observed under magnification with an optical microscope, slight bleeding was confirmed. In contrast, in the microchannel device fabricated using the channel wall forming material of Example 1, the channels were completely filled with water in 260 seconds, which was 30 seconds faster than in Comparative Example 1.

[0072] This shows that in Example 1, highly hydrophobic wax is present at the position of the flow path wall W shown in Figure 6, blocking water flowing through the flow path 82, resulting in a flow path device that can allow liquid to flow more efficiently without bleeding. In Example 2, a microchannel device was fabricated using a channel wall forming material in which the difference in SP value between the thermoplastic resin and the wax was larger than that in Example 1. In Example 2, it took 245 seconds for water to fill the entire channel, which was 15 seconds faster than in Example 1.

[0073] Furthermore, when observed by the "Method of measuring wax in the cross section of the flow channel wall" described below, it was confirmed that the amount of wax present in the region of the flow channel wall surface facing the flow channel (position W in FIG. 6) was greater in Example 2 than in Example 1. In other words, it was confirmed that a flow channel device with higher hydrophobicity could be produced by using a flow channel wall forming material containing a thermoplastic resin and wax with a large SP value difference as in Example 2.

[0074] Furthermore, in Example 3, a microchannel device was fabricated using a channel wall forming material in which the difference in SP value between the thermoplastic resin and the wax was even greater than in Example 2. The weight average molecular weight (Mw) of the wax W3 was smaller than the weight average molecular weights of the waxes used in Examples 1 and 2. In Example 3, in the performance evaluation, the time until the entire channel was filled with water was even shorter, at 225 seconds.

[0075] <Method of measuring wax on the cross section of the channel wall> In the present invention, an electronic staining method is used that utilizes the difference in the microstructure between the crystalline phase (wax) and the amorphous phase (thermoplastic resin) to increase the electron density of one of the components by using a heavy metal to create a contrast between the materials. Specifically, the flow channel device modified with osmium tetroxide (OsO4) is cured in a photocurable epoxy resin. Then, from the cured product, a 500 μm square, 20 μm thick slice sample is cut out obliquely (in the direction of the dashed line in Fig. 6, angle θ) using an ultramicrotome (UC7, Leica) equipped with a diamond knife so that the cross-sections of the flow channel walls of the flow channel device in Fig. 6, 91 and 92, can be observed.

[0076] Next, electron staining is performed in combination with ruthenium tetroxide (RuO4). Specifically, a vacuum electron staining apparatus (VSC4R1H manufactured by Filgen) is used, the sliced ​​sample is placed in a chamber, and staining treatment is performed in an atmosphere of RuO4 gas at 500 Pa for a staining time of 15 minutes. The stained sample is magnified 10,000 times using the scanning image mode of a scanning transmission electron microscope (JEM2800, JEOL) to obtain images of the region W on the side of the flow channel wall facing the flow channel and the inside B of the flow channel wall in the cross section of the flow channel device in Figure 6.

[0077] At this time, the probe size of the scanning transmission electron microscope (STEM) was 1 nm, the image size was 2048 pixels × 2048 pixels, and the accelerating voltage was 200 KV to obtain a cross-sectional image. The wax was identified in the cross-sectional images using an energy dispersive X-ray spectrometer (EDX) and other instruments. The proportion of wax in the area of ​​the flow channel wall facing the flow channel was measured from the flow channel side, over a 10 μm square area at position 91, 20 μm from the position where the wax component began to be detected (point 0; 95 in Figure 6) toward point 96. The thickness is set to 20 μm because the state of the channel wall 20 μm from the interface where the channel wall comes into contact with the channel side, due to the water repellency of the channel wall, affects the flow rate of the sample flowing through the channel. The measurement object is a sample in which the distance from the 0 point (95 in FIG. 6) to the substrate surface 96 is 200 μm or more.

[0078] The wax parts are stained with ruthenium tetroxide (RuO4) in a different amount than the surrounding resin, creating a clear contrast and making the wax parts easy to identify. In addition, the proportion of wax inside the flow path wall was measured in a 10 μm square at a position more than 20 / cosθ (μm) away from the above 96 toward point 0 and more than 10 μm away from the surface of the porous substrate. Furthermore, with regard to the proportion of wax in region X (the region of the flow path wall not facing the flow path and which is the surface of the porous substrate and the region in its vicinity), the proportion of wax in the region from the surface of the porous substrate to a depth of 10 μm was used. In all cases, the proportion of wax is calculated using the following formula (3), where C is the area occupied by the flow path wall material (including wax, excluding the porous substrate) and D is the area occupied by the wax. Wax ratio = D / C x 100 (3)

[0079] <Confirmation of contact angle of hydrophobic flow channel device> The contact angle of water on the surface of the microchannel device produced in Example 1 was measured using a CA-W type contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd.). Wax was present on surface 93 shown in FIG. 6, and the contact angle was 120 degrees. Furthermore, the contact angle of the surface with water when the wax component on the surface 93 was dissolved with hexane and removed from the surface and then measured was 100 degrees. Generally, a higher contact angle indicates higher water repellency, and this result also shows that the surface side of the flow channel wall is more water repellent than the inside of the flow channel wall. Therefore, it is considered that the surface of the flow channel wall that comes into contact with the sample in the flow channel (the interface between the flow channel and the flow channel wall) also has high water repellency. Furthermore, when the bending resistance of the obtained microchannel devices was checked, all the devices showed good bending resistance.

[0080] <Production method> As described above, by forming a channel pattern by electrophotographically placing a channel wall forming material containing a thermoplastic resin and a wax having an SP value lower than that of the thermoplastic resin on the surface of a porous substrate, and then melting the material by heat to form a channel in a microchannel device, the wax content in the surface region of the channel wall facing the channel is increased, and the hydrophobicity of the channel wall is improved. Therefore, a stable microchannel device can be fabricated that suppresses the risk of the sample bleeding onto the channel wall and allows the sample to move more efficiently by capillary action.

[0081] <Example 4> Resin particles T5 for forming flow path walls were prepared by changing the amount of wax in resin particles T3 to 15 parts by mass, and resin particles T6 for forming flow path walls were prepared by changing the amount of wax to 7 parts by mass. In the flow channel pattern formed on the surface of the porous substrate, resin particles T5 were used in a 1.0 mm wide region on the flow channel side of the region that would become the flow channel wall, and resin particles T6 were used in the other parts of the region that would form the flow channel wall. Next, the formed flow channel pattern was permeated into the porous substrate by heating, to produce a microflow channel device. The fabricated microchannel device had flow channel walls with excellent hydrophobicity, and had a small amount of wax on the surface, making it well suited to being configured to overlay other layers or components.

[0082] <Example 5> Resin particles T5 for forming flow path walls were prepared by changing the amount of wax in resin particles T3 for forming flow path walls to 15 parts by mass, and resin particles T7 for forming flow path walls were prepared by changing the amount of wax in resin particles T1 for forming flow path walls to 3 parts by mass. In the flow channel pattern formed on the surface of the porous substrate, resin particles T5 were used in a 1.0 mm wide region on the flow channel side of the region that would become the flow channel wall, and resin particles T7 were used in the other parts of the region that would form the flow channel wall. Next, the formed flow channel pattern was permeated into the porous substrate by heating, to produce a microflow channel device. The fabricated microchannel device had flow channel walls with excellent hydrophobicity and contained even less wax on the surface than the device fabricated in Example 4, and therefore was more suitable for use in configurations in which other layers or components were overlaid.

[0083] [Table 4] [Explanation of symbols]

[0084] 4. Transfer roller 5. Intermediate transfer body 6. Primary transfer roller 7. Secondary transfer roller P... Process cartridge 11. Photosensitive drum 12. Charging roller 14. Cleaning blade 15. Memory 20. Developing device 21. Developing container 23. Developing roller 24...Resin particle supply roller 25. Development blade 71... Charging high voltage power supply 72. High voltage power supply for development 73. Exposure unit 74. Transfer high voltage power supply 75‥Contact / separation means 76. Development speed 80. Flow path pattern 81. Image of particles forming flow channel walls 82. Flow path 83. Reagent Section 84. Testing liquid section 100: Flow path pattern image forming unit T ‥Particles for forming channel walls B ‥Thermoplastic resin W...Wax

Claims

1. A microchannel device having a channel sandwiched between channel walls formed inside a porous substrate, the flow path wall contains a thermoplastic resin and a wax; A microchannel device, characterized in that a proportion of the wax in a region of the flow channel wall facing the flow channel is higher than a proportion of the wax inside the flow channel wall.

2. The microchannel device according to claim 1 , wherein the wax has a lower SP value than the thermoplastic resin.

3. The SP value of the wax is expressed as SP(W) (cal / cm ３ ) １／２ The SP value of the thermoplastic resin is SP(B) (cal / cm ３ ) １／２ The microchannel device according to claim 1 , which satisfies the following formula (1) when SP(B)-SP(W)≧0.5 (1)

4. The microchannel device according to any one of claims 1 to 3, wherein the wax has a weight average molecular weight of 300 or more and 10,000 or less.

5. 5. The microchannel device according to claim 1, wherein a ratio of wax in a region of the flow channel wall facing the flow channel is higher than a ratio of wax in a region X that satisfies the following requirement: Region X: a region of the flow path wall not facing the flow path, and which is the surface of the porous substrate and a region in its vicinity.

6. The microchannel device according to claim 5 , wherein the proportion of wax in the region X is 15% or less.

7. The microchannel device according to claim 5 , wherein the proportion of wax in the region X is 8% or less.

8. A method for manufacturing a microchannel device in which a channel sandwiched between channel walls is formed inside a porous substrate, comprising the steps of: A step of electrophotographically depositing a flow path wall forming material containing a thermoplastic resin and a wax on the surface of the porous substrate to form a flow path pattern on the surface of the porous substrate; and The flow path wall forming material forming the flow path pattern is melted by heat, and the flow path wall forming material is permeated into the inside of the porous substrate to form a flow path wall inside the porous substrate, The SP value of the wax is lower than the SP value of the thermoplastic resin. A method for producing a microchannel device comprising the steps of:

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