Blood collection container and plasma separation method

Abstract

Provided is a blood collection container that can prevent adhesion of a blood separating composition to unintended parts of the inner wall surface of the blood collection container body when centrifuging after blood collection. [Solution] The blood collection container of the present invention comprises a blood collection container body, a blood separating composition contained in the blood collection container body, and an aqueous solution contained in the blood collection container body, wherein the blood separating composition contains an organic component that is fluid at 25°C and an inorganic fine powder, the organic component contains a resin, and the aqueous solution contains an anticoagulant and water, and the combination of the blood separating composition and the aqueous solution is such that the rate of change A of the contact angle expressed by specific formula (A) is greater than the rate of change B of the contact angle expressed by specific formula (B).

Description

[Technical Field]

[0001] The present invention relates to a blood collection container and a method for separating plasma using the blood collection container. [Background technology]

[0002] In clinical testing, blood collection containers such as blood collection tubes are widely used to collect blood. As described in Patent Document 1, a known example of such a blood collection container is one that contains a blood separation composition containing a resin and an inorganic powder, and an anticoagulant. After collecting blood in this blood collection container, the blood can be separated into plasma and blood cell components by centrifuging the blood collection container. In this case, the plasma is located above the blood separation composition, and the blood cell components are located below the blood separation composition, with the blood separation composition acting as a barrier separating the plasma from the blood cell components. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2010 / 053180A1 Summary of the Invention [Problem to be solved by the invention]

[0004] As a blood collection container, a blood collection container in which an anticoagulant is dissolved in water and contained within the blood collection container body (a blood collection container containing an aqueous solution containing an anticoagulant) is sometimes used.

[0005] However, in conventional blood collection containers containing an aqueous solution containing an anticoagulant, a relatively large amount of blood separation composition may adhere to unintended portions of the inner wall surface of the blood collection container body when the blood is collected and centrifuged. For example, a relatively large amount of blood separation composition may adhere to the inner wall surface of the blood collection container body that should come into contact with plasma. This situation is shown in Figure 3. The blood collection container 100 shown in Figure 3 is a blood collection container after blood has been collected and centrifuged. In the blood collection container 100, blood separation composition 300 is adhered to the inner wall surface portions R1 and R2 of the blood collection container body 200 that should come into contact with plasma 800. It is not originally intended that blood separation composition 300 adhere to the inner wall surface portions R1 and R2 of the blood collection container body 200. In Figure 3, reference numeral 900 denotes a blood cell component.

[0006] If a relatively large amount of blood separation composition adheres to unintended areas of the inner wall surface of the blood collection container body, the blood separation composition may adhere to the sample suction nozzle of the automatic analyzer, preventing accurate sample suction.

[0007] The present invention aims to provide a blood collection container that can prevent adhesion of a blood separation composition to unintended portions of the inner wall surface of the blood collection container body when centrifuged after blood collection. Another object of the present invention is to provide a method for separating plasma using the above blood collection container. [Means for solving the problem]

[0008] The present specification discloses the following blood collection container and plasma separation method.

[0009] Item 1. A blood collection container comprising a blood collection container body, a blood separating composition contained in the blood collection container body, and an aqueous solution contained in the blood collection container body, wherein the blood separating composition contains an organic component that is fluid at 25°C and an inorganic fine powder, the organic component contains a resin, the aqueous solution contains an anticoagulant and water, and the combination of the blood separating composition and the aqueous solution is such that the rate of change A of the contact angle represented by the following formula (A) is greater than the rate of change B of the contact angle represented by the following formula (B).

[0010] Contact angle change rate A (%) = [(θ1 - θ2) / θ1] × 100 (A)

[0011] θ1: Contact angle (°) of the aqueous solution with the blood separating composition 5 seconds after 2 μL of the aqueous solution is dropped onto the surface of the blood separating composition θ2: Contact angle (°) of the aqueous solution with the blood separating composition 100 seconds after 2 μL of the aqueous solution is dropped onto the surface of the blood separating composition

[0012] Contact angle change rate B (%) = [(θ3 - θ4) / θ3] × 100 (B)

[0013] θ3: Contact angle (°) of pure water with the blood separating composition 5 seconds after 2 μL of pure water is dropped onto the surface of the blood separating composition θ4: Contact angle (°) of pure water with the blood separating composition 100 seconds after 2 μL of pure water is dropped onto the surface of the blood separating composition

[0014] Item 2. The blood collection container according to Item 1, wherein the absolute value of the difference between the rate of change A of the contact angle and the rate of change B of the contact angle is 5% or more.

[0015] Item 3. The blood collection container according to Item 1 or 2, wherein the absolute value of the difference between the rate of change A of the contact angle and the rate of change B of the contact angle is 30% or less.

[0016] Item 4. The blood collection container according to any one of Items 1 to 3, wherein the aqueous solution contains a wettability modifier.

[0017] Item 5. The blood collection container according to Item 4, wherein the wettability modifier is a surfactant.

[0018] Item 6. The blood collection container according to Item 4 or 5, wherein the wettability modifier is a silicone surfactant.

[0019] Item 7. The blood collection container according to any one of Items 1 to 6, wherein the resin comprises a petroleum-based resin, a cyclopentadiene-based resin, a polyester-based resin, or a (meth)acrylic-based resin.

[0020] Item 8. The blood collection container according to any one of Items 1 to 7, wherein the specific gravity of the blood separating composition at 25°C is 1.025 or more and 1.090 or less.

[0021] Item 9. A method for separating plasma, comprising the steps of collecting blood in the blood collection container according to any one of Items 1 to 8, and centrifuging the blood collection container into which the blood has been collected. [Effects of the Invention]

[0022] The blood collection container according to the present invention comprises a blood collection container body, a blood separation composition contained in the blood collection container body, and an aqueous solution contained in the blood collection container body. In the blood collection container according to the present invention, the blood separation composition contains an organic component that is fluid at 25°C and an inorganic fine powder, the organic component contains a resin, and the aqueous solution contains an anticoagulant and water. In the blood collection container according to the present invention, the combination of the blood separation composition and the aqueous solution is such that the rate of change A of the contact angle expressed by specific formula (A) is greater than the rate of change B of the contact angle expressed by specific formula (B). Because the blood collection container according to the present invention has the above configuration, adhesion of the blood separation composition to unintended parts of the inner wall surface of the blood collection container body can be suppressed when centrifuged after blood collection. [Brief explanation of the drawings]

[0023] [Figure 1]FIG. 1 is a front cross-sectional view that schematically shows a blood collection container according to one embodiment of the present invention. [Figure 2] FIG. 2 is a front cross-sectional view that schematically shows how blood is separated into plasma and blood cell components using the blood collection container shown in FIG. [Figure 3] FIG. 3 is a front cross-sectional view that schematically shows how blood is separated into plasma and blood cell components using a conventional blood collection container. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present invention will be described in detail below.

[0025] The blood collection container according to the present invention comprises a blood collection container body, a blood separating composition contained in the blood collection container body, and an aqueous solution contained in the blood collection container body. In the blood collection container according to the present invention, the blood separating composition contains an organic component that is fluid at 25°C and an inorganic fine powder, the organic component contains a resin, and the aqueous solution contains an anticoagulant and water.

[0026] In the blood collection container of the present invention, the combination of the blood separating composition and the aqueous solution is such that the rate of change A of the contact angle represented by the following formula (A) is greater than the rate of change B of the contact angle represented by the following formula (B).

[0027] Contact angle change rate A (%) = [(θ1 - θ2) / θ1] × 100 (A)

[0028] θ1: Contact angle (°) of the aqueous solution with the blood separating composition 5 seconds after 2 μL of the aqueous solution is dropped onto the surface of the blood separating composition θ2: Contact angle (°) of the aqueous solution with the blood separating composition 100 seconds after 2 μL of the aqueous solution is dropped onto the surface of the blood separating composition

[0029] Contact angle change rate B (%) = [(θ3 - θ4) / θ3] × 100 (B)

[0030] θ3: Contact angle (°) of pure water with the blood separating composition 5 seconds after 2 μL of pure water is dropped onto the surface of the blood separating composition θ4: Contact angle (°) of pure water with the blood separating composition 100 seconds after 2 μL of pure water is dropped onto the surface of the blood separating composition

[0031] The blood collection container according to the present invention is provided with the above-described configuration, and therefore, when centrifuged after blood collection, adhesion of the blood separation composition to unintended parts of the inner wall surface of the blood collection container body can be suppressed.

[0032] In conventional blood collection containers containing an aqueous solution containing an anticoagulant, when blood is collected and centrifuged, a relatively large amount of a blood separating composition may adhere to unintended portions of the inner wall surface of the blood collection container body. After extensive investigation, the present inventors have found the following (1) to (3) to be the causes of this.

[0033] (1) Due to the presence of an aqueous solution, resin components may migrate from the surface of the blood separating composition into the aqueous solution during storage or transportation of the blood collection container.

[0034] (2) When the blood collection container is stored or transported, it may be turned sideways or tilted, causing the resin components that have migrated into the aqueous solution to adhere to the inner wall surface of the blood collection container body or to form a coating on the inner wall surface of the blood collection container body.

[0035] (3) When blood is centrifuged after collection, the resin component that has adhered to or formed a coating on the inner wall surface of the blood collection container body serves as a scaffold for the blood separation composition to further adhere to the resin component, resulting in a relatively large amount of the blood separation composition adhering to unintended parts of the inner wall surface of the blood collection container body.

[0036] After extensive research, the inventors have found that the specific combination of the blood separation composition and aqueous solution described above makes it possible to prevent the blood separation composition from adhering to unintended areas on the inner wall surface of the blood collection container body when centrifuged after blood collection. The reason for this is presumed to be, but is not limited to, that the good wettability of the blood separation composition with the aqueous solution prevents the migration of resin components from the surface of the blood separation composition into the aqueous solution, making the above-mentioned cause (1) less likely to occur.

[0037] Therefore, although the blood collection container according to the present invention is a blood collection container containing an aqueous solution, the above-described configuration prevents the blood separation composition from adhering to unintended portions of the inner wall surface of the blood collection container body when centrifuged after blood collection. This prevents the blood separation composition from adhering to the sample suction nozzle of an automated analyzer. Furthermore, the appearance of the blood collection container after centrifugation can be improved.

[0038] From the viewpoint of exerting the effects of the present invention, the combination of the blood separating composition and the aqueous solution is a combination in which the rate of change A of the contact angle is larger than the rate of change B of the contact angle.

[0039] The absolute value of the difference between the rate of change A of the contact angle and the rate of change B of the contact angle is preferably 5% or more, more preferably 10% or more, preferably 80% or less, more preferably 50% or less, and even more preferably 30% or less. When the blood separation composition has good wettability with the aqueous solution, the aqueous solution dropped on the surface of the blood separation composition gradually spreads and wets the surface, resulting in a large rate of change A of the contact angle. Therefore, from the perspective of more effectively exerting the effects of the present invention, it is preferable that the absolute value of the difference between the rate of change A of the contact angle and the rate of change B of the contact angle is large. Furthermore, when the absolute value of the difference is equal to or less than the upper limit, hemolysis can be effectively suppressed.

[0040] The absolute value of the difference between the rate of change A of the contact angle and the rate of change B of the contact angle is expressed by the formula: |rate of change A of the contact angle - rate of change B of the contact angle|. Since the units of the rate of change A of the contact angle and the rate of change B of the contact angle are both "%", the unit of the absolute value of the difference is also "%".

[0041] Examples of a method for making the rate of change A of the contact angle larger than the rate of change B of the contact angle and for controlling the absolute value of the difference within the preferred range include adding a wettability modifier (e.g., a surfactant) to the aqueous solution. Increasing the concentration of the wettability modifier in the aqueous solution tends to increase the absolute value of the difference.

[0042] The contact angle change rate A is preferably 10% or more, more preferably 20% or more, even more preferably 30% or more, even more preferably 40% or more, and particularly preferably 50% or more. When the contact angle change rate A is equal to or greater than the lower limit, the effects of the present invention can be more effectively exhibited. The contact angle change rate A may be 90% or less, 80% or less, or 70% or less.

[0043] The rate of change B of the contact angle may be 10% or more, 20% or more, 30% or more, 90% or less, 80% or less, 70% or less, or 60% or less.

[0044] The contact angle (θ2) of the aqueous solution is preferably 90° or less, more preferably 70° or less, and even more preferably 50° or less. When the contact angle (θ2) of the aqueous solution is equal to or less than the upper limit, the effects of the present invention can be more effectively exhibited. The contact angle (θ2) of the aqueous solution may be 10° or more.

[0045] The contact angle (θ1) of the aqueous solution is preferably larger than the contact angle (θ2) of the aqueous solution.

[0046] The contact angle (θ3) of pure water is preferably larger than the contact angle (θ4) of pure water.

[0047] The contact angle (θ2) of the aqueous solution is preferably smaller than the contact angle (θ4) of the pure water, in which case the effects of the present invention can be more effectively exhibited.

[0048] The absolute value of the difference between the contact angle (θ2) of the aqueous solution and the contact angle (θ4) of pure water is preferably 5° or more, more preferably 10° or more. When the absolute value of the difference is equal to or greater than the lower limit, the effects of the present invention can be more effectively exhibited. The absolute value of the difference between the contact angle (θ2) of the aqueous solution and the contact angle (θ4) of pure water may be 30° or less, or may be 20° or less.

[0049] The absolute value of the difference between the contact angle of the aqueous solution (θ2) and the contact angle of pure water (θ4) is expressed by the formula |θ2-θ4|. Since the units of θ2 and θ4 are both "°", the unit of the absolute value of the difference is also "°".

[0050] The contact angles (θ1, θ2) of the aqueous solution and the contact angles (θ3, θ4) of the pure water are measured by the sessile drop method in accordance with JIS-R3527:1999. The contact angles (θ1, θ2) of the aqueous solution and the contact angles (θ3, θ4) of the pure water are static contact angles. The contact angles (θ1, θ2) of the aqueous solution and the contact angles (θ3, θ4) of the pure water are measured using a contact angle measuring device (for example, "DMo-502" manufactured by Kyowa Interface Science Co., Ltd.). Specifically, they are measured as follows.

[0051] At 25°C, 2 µL of the above aqueous solution is dropped vertically onto the surface of the blood separation composition. Five seconds after dropping, the angle between the aqueous solution and the surface of the blood separation composition is measured using the θ / 2 method, and this angle is defined as the contact angle (θ1) of the aqueous solution. 100 seconds after dropping, the angle between the aqueous solution and the surface of the blood separation composition is measured using the θ / 2 method, and this angle is defined as the contact angle (θ2) of the aqueous solution.

[0052] Similarly, 2 μL of the above pure water is dropped vertically onto the surface of the blood separating composition at 25° C. Five seconds after dropping, the angle between the pure water and the surface of the blood separating composition is measured using the θ / 2 method, and this angle is defined as the contact angle of pure water (θ3). 100 seconds after dropping, the angle between the pure water and the surface of the blood separating composition is measured using the θ / 2 method, and this angle is defined as the contact angle of pure water (θ4).

[0053] In the θ / 2 method, the contact angle is determined by the following formula (1).

[0054] θ=2×arctan(h / r) (1)

[0055] θ: contact angle r: droplet radius h: Droplet height

[0056] The blood collection container according to the present invention will be described in detail below. In this specification, "(meth)acrylic" means either or both of "acrylic" and "methacrylic".

[0057] (Blood separation composition) The blood collection container includes the blood separation composition. The blood separation composition is contained within the blood collection container body. The blood separation composition is a composition that migrates between the plasma layer and the blood cell layer during centrifugation to form a partition. The blood separation composition is also used for the purpose of preventing component migration between the plasma layer and the blood cell layer after centrifugation. A conventionally known blood separation composition can be used as the blood separation composition. The blood separation composition preferably has thixotropy. The blood separation composition may be contained in the bottom of the blood collection container body or may be disposed on the side wall surface of the blood collection container body. The blood separation composition is preferably contained in the bottom of the blood collection container body.

[0058] The blood separation composition contains an organic component that has fluidity at 25°C and an inorganic fine powder. This increases the fluidity of the blood separation composition, and the strength of the partition wall formed by centrifugation can be increased. The organic component that has fluidity at 25°C may be used alone, or two or more types may be used in combination. The inorganic fine powder may be used alone, or two or more types may be used in combination.

[0059] <Organic components that are fluid at 25°C> The above phrase "having fluidity at 25°C" means that the viscosity at 25°C is 500 Pa·s or less.

[0060] The viscosity of the organic component at 25°C is preferably 10 Pa s or more, more preferably 30 Pa s or more, and preferably 200 Pa s or less, more preferably 100 Pa s or less. When the viscosity is equal to or greater than the above lower limit and equal to or less than the above upper limit, the fluidity of the composition for separating blood is increased, and the strength of the partition wall formed after centrifugation can be increased.

[0061] The viscosity of the organic component at 25°C was measured using an E-type viscometer (for example, "TVE-35" manufactured by Toki Sangyo Co., Ltd.) at 25°C and a shear rate of 1.0 sec. -1 It is measured under the following conditions.

[0062] Examples of the organic component include a resin and a mixture of a resin and an organic compound such as a plasticizer. The organic component includes a resin. The organic component preferably includes a resin and an organic compound. The organic component is preferably a mixture of a resin and an organic compound. When the organic component is a mixture of a resin and an organic compound, it is sufficient that the mixture (the organic component) has fluidity, and the resin or the organic compound does not have to have fluidity. When the organic component is a mixture of a resin and an organic compound, the resin may be, for example, a resin that is solid at 25°C. Only one type of the resin and the organic compound may be used, or two or more types may be used in combination.

[0063] Examples of the resin include petroleum-based resins, cyclopentadiene-based resins, polyester-based resins, polyurethane-based resins, (meth)acrylic resins, silicone-based resins, α-olefin-fumaric acid ester copolymers, copolymers of sebacic acid, 2,2-dimethyl-1,3-propanediol, and 1,2-propanediol, polyether polyurethane-based resins, polyether polyester-based resins, etc. Only one of the above resins may be used, or two or more of them may be used in combination.

[0064] The resin preferably contains a petroleum-based resin, a cyclopentadiene-based resin, a polyester-based resin, or a (meth)acrylic resin, more preferably a petroleum-based resin, a cyclopentadiene-based resin, or a (meth)acrylic resin, and even more preferably a (meth)acrylic resin. In this case, the fluidity of the blood separation composition is further improved, and the strength of the partition wall formed after centrifugation can be further increased. In addition, in this case, it is easier to adjust the rate of change A of the contact angle and the rate of change B of the contact angle.

[0065] Commercially available petroleum-based resins include "Regalite S5090" manufactured by Eastman Chemical Company.

[0066] Examples of the cyclopentadiene resin include a polymer of a cyclopentadiene monomer, a copolymer of a cyclopentadiene monomer and an aromatic monomer, and a dicyclopentadiene resin. The cyclopentadiene resin may be hydrogenated. The polymer of a cyclopentadiene monomer and the copolymer of a cyclopentadiene monomer and an aromatic monomer may be an oligomer.

[0067] Examples of the cyclopentadiene-based monomer include cyclopentadiene, dicyclopentadiene, and alkyl-substituted derivatives of cyclopentadiene.

[0068] Examples of the aromatic monomer include styrene, methylstyrene, indene, and methylindene.

[0069] Commercially available dicyclopentadiene resins include "Scoretz SU500" and "Scoretz SU90" manufactured by Colon Co., Ltd.

[0070] Examples of the polyester resin include polyalkylene terephthalate resins and polyalkylene naphthalate resins, etc. Examples of the polyalkylene terephthalate resin include polyethylene terephthalate, polybutylene terephthalate, and poly-1,4-cyclohexanedimethylene terephthalate.

[0071] Examples of the polyurethane resin include a reaction product of a polyol compound and an isocyanate compound.

[0072] Examples of the (meth)acrylic resin include a resin obtained by polymerizing at least one type of (meth)acrylic acid ester monomer, and a resin obtained by polymerizing at least one type of (meth)acrylic acid ester monomer and at least one type of monomer other than a (meth)acrylic acid ester monomer.

[0073] Examples of the (meth)acrylic acid ester monomer include (meth)acrylic acid alkyl esters, (meth)acrylic acid polyalkylene glycol esters, (meth)acrylic acid alkoxyalkyl esters, (meth)acrylic acid hydroxyalkyl esters, (meth)acrylic acid glycidyl esters, (meth)acrylic acid dialkylaminoalkyl esters, (meth)acrylic acid benzyl esters, (meth)acrylic acid phenoxyalkyl esters, (meth)acrylic acid cyclohexyl esters, (meth)acrylic acid isobornyl esters, and (meth)acrylic acid alkoxysilylalkyl esters. When the (meth)acrylic acid ester monomer has an alkyl group, the number of carbon atoms in the alkyl group is preferably 1 or more and preferably 20 or less. The (meth)acrylic acid alkyl ester is preferably a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms. The (meth)acrylic acid ester monomers may be used alone or in combination of two or more.

[0074] The organic compound may be a benzene polycarboxylic acid alkyl ester derivative. The organic compound is preferably a benzene polycarboxylic acid alkyl ester derivative. Therefore, the organic component is preferably a mixture of the resin and the benzene polycarboxylic acid alkyl ester derivative.

[0075] Examples of the benzene polycarboxylic acid alkyl ester derivatives include phthalates, trimellitates, pyromellitates, etc. The benzene polycarboxylic acid alkyl ester derivatives may be used alone or in combination of two or more.

[0076] Examples of the trimellitic acid ester include tri-n-octyl trimellitate, triisooctyl trimellitate, and triisodecyl trimellitate.

[0077] Examples of the pyromellitic acid ester include tetraisooctyl pyromellitic acid.

[0078] Commercially available trimellitic acid esters include "Monocizer W700" and "Monocizer W-750" manufactured by DIC Corporation, and "Sansocizer TO™" and "Sansocizer TI™" manufactured by New Japan Chemical Co., Ltd.

[0079] Commercially available pyromellitic acid esters include "Monocizer W-7010" manufactured by DIC Corporation.

[0080] The benzenepolycarboxylic acid alkyl ester derivative is preferably a phthalate ester, a trimellitate ester, or a pyromellitate ester, and more preferably a trimellitate ester.

[0081] The content of the organic component in 100% by weight of the blood separating composition is preferably 80% by weight or more, more preferably 85% by weight or more, even more preferably 90% by weight or more, and preferably 98% by weight or less. In this case, the fluidity of the blood separating composition is further increased, and the strength of the partition wall formed after centrifugation can be further increased. In addition, in this case, it is easier to adjust the contact angle change rate A and the contact angle change rate B.

[0082] <Inorganic fine powder> Examples of the inorganic fine powder include fine silica powder, titanium oxide powder, calcium carbonate powder, zinc oxide powder, alumina powder, fine glass powder, talc powder, kaolin powder, bentonite powder, titania powder, and zirconium powder.

[0083] The inorganic fine powder is preferably fine silica, titanium oxide powder, calcium carbonate powder, zinc oxide powder, alumina powder, glass fine powder, talc powder, kaolin powder, bentonite powder, titania powder, or zirconium powder.

[0084] From the viewpoint of maintaining both the specific gravity and thixotropy of the blood separating composition within suitable ranges, the inorganic fine powder preferably contains finely powdered silica. When obtaining a blood separating composition having a specific gravity of 1.050 or more at 25°C, the inorganic fine powder more preferably contains finely powdered silica and an inorganic fine powder other than finely powdered silica (second inorganic fine powder). However, even when the specific gravity of the blood separating composition at 25°C is 1.050 or more, the inorganic fine powder does not have to contain the second inorganic fine powder. Furthermore, even when the specific gravity of the blood separating composition at 25°C is less than 1.050, the inorganic fine powder may contain the second inorganic fine powder. Each of the inorganic fine powder, the finely powdered silica, and the second inorganic fine powder may be used alone or in combination of two or more.

[0085] The finely powdered silica includes natural silica and synthetic silica. Synthetic silica includes hydrophilic silica and hydrophobic silica. Hydrophilic silica, for example, imparts thixotropy to the blood separation composition by hydrogen bonding between hydroxyl groups on the particle surface, and also has the effect of adjusting the specific gravity. On the other hand, hydrophobic silica has a smaller effect of imparting thixotropy than hydrophilic silica.

[0086] From the viewpoint of maintaining both the specific gravity and thixotropy of the blood separation composition within a suitable range, the finely powdered silica preferably contains hydrophilic silica, and more preferably contains both hydrophilic and hydrophobic silica.

[0087] The second inorganic fine powder is preferably an inorganic fine powder having a higher specific gravity than fine silica powder, and more preferably an inorganic fine powder having a specific gravity of 2.5 or more, such as zinc oxide powder, titanium oxide powder, alumina powder, calcium carbonate powder, etc. The specific gravity of the second inorganic fine powder may be 10 or less, or may be 6 or less.

[0088] The average particle diameters of the inorganic fine powder, the fine silica powder, and the second inorganic fine powder are not particularly limited, and may be 1 nm or more, 10 nm or more, 500 nm or less, or 100 nm or less.

[0089] The average particle diameters of the inorganic fine powder, the fine silica powder, and the second inorganic fine powder are average diameters measured on a volume basis (volume average particle diameter), and are the 50% median diameter (D50) values. The volume average particle diameter (D50) can be measured by laser diffraction / scattering method, image analysis method, Coulter method, centrifugal sedimentation method, etc. The volume average particle diameter (D50) is preferably determined by laser diffraction / scattering method or image analysis method.

[0090] The specific surface area of ​​the finely powdered silica is not particularly limited. 2 / g or more, and 2 / g or more, and 2 / g or less, and 2 / g or less.

[0091] The specific surface area of ​​the finely powdered silica is measured by the BET method.

[0092] The content of the hydrophilic silica in 100% by weight of the blood separating composition is preferably 0.01% by weight or more, more preferably 0.10% by weight or more, even more preferably 0.30% by weight or more, and preferably 2.50% by weight or less, more preferably 2.00% by weight or less. When the content of the hydrophilic silica is equal to or more than the lower limit and equal to or less than the upper limit, both the specific gravity and thixotropy of the blood separating composition can be maintained within more suitable ranges.

[0093] The content of the finely powdered silica in 100% by weight of the blood separating composition is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and preferably 10% by weight or less, more preferably 7% by weight or less. When the content of the finely powdered silica is equal to or more than the lower limit and equal to or less than the upper limit, both the specific gravity and thixotropy of the blood separating composition can be maintained within more suitable ranges.

[0094] The content of the second inorganic fine powder in 100% by weight of the blood separating composition is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and preferably 10% by weight or less, more preferably 7% by weight or less. When the content of the second inorganic fine powder is equal to or more than the lower limit and equal to or less than the upper limit, the specific gravity of the blood separating composition can be effectively increased.

[0095] The content of the inorganic fine powder in 100% by weight of the blood separating composition is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and preferably 10% by weight or less, more preferably 8% by weight or less. When the content of the inorganic fine powder is equal to or more than the lower limit and equal to or less than the upper limit, the specific gravity of the blood separating composition can be effectively increased.

[0096] Other Ingredients: The blood separation composition may contain other components in addition to the components described above, as long as the effects of the present invention are not impaired. Examples of such other components include organic gelling agents, thermoplastic elastomers, polyalkylene glycols, silicone oils, cosolvents, antioxidants, colorants, and water. Each of the other components may be used alone or in combination of two or more.

[0097] The specific gravity of the blood separation composition at 25° C. is preferably 1.025 or more, more preferably 1.030 or more, even more preferably 1.035 or more, and preferably 1.090 or less, more preferably 1.085 or less, and even more preferably 1.080 or less. When the specific gravity of the blood separation composition at 25° C. is equal to or more than the above lower limit and equal to or less than the above upper limit, plasma can be well separated from blood, and contamination of plasma with white blood cells, red blood cells, and platelets can be effectively suppressed.

[0098] The specific gravity of the blood separating composition at 25°C is measured by dropping one drop of the composition into successively adjusted saline solutions at 25°C with specific gravities of 0.002 each, and observing the saline solution float and sink. The specific gravity of the saline solution at 25°C is measured using a hydrometer (for example, the "DA-130N" manufactured by Kyoto Electronics Manufacturing Co., Ltd.).

[0099] The viscosity of the blood separating composition at 25°C is preferably 50 Pa s or more, more preferably 70 Pa s or more, and preferably 500 Pa s or less, more preferably 400 Pa s or less. When the viscosity is equal to or greater than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited.

[0100] The viscosity of the blood separation composition at 25°C was measured using an E-type viscometer (for example, "TVE-35" manufactured by Toki Sangyo Co., Ltd.) at 25°C and a shear rate of 1.0 sec. -1 It is measured under the following conditions.

[0101] (aqueous solution) The blood collection container includes the aqueous solution, which is contained within the blood collection container body and contains an anticoagulant and water.

[0102] <Anticoagulant> As the anticoagulant, any of the conventionally known anticoagulants can be used. The anticoagulants may be used alone or in combination of two or more.

[0103] Examples of the anticoagulant include heparin, metal salts of heparin, ethylenediaminetetraacetic acid (EDTA), metal salts of EDTA, citric acid, and sodium citrate. Examples of the sodium citrate include trisodium citrate.

[0104] From the viewpoint of exhibiting good anticoagulant performance, the anticoagulant is preferably EDTA, a metal salt of EDTA, heparin, a metal salt of heparin, or sodium citrate.

[0105] The concentration of the anticoagulant in the aqueous solution is not particularly limited as long as it is a concentration at which anticoagulant performance is exhibited.

[0106] <Water> The aqueous solution contains water, which serves as a solvent. The water may be pure water.

[0107] In the above aqueous solution (100% by weight), the water content is preferably 40% by weight or more, more preferably 70% by weight or more, even more preferably 80% by weight or more, particularly preferably 90% by weight or more, preferably 99% by weight or less, more preferably 98% by weight or less.

[0108] <Wettability modifier> The aqueous solution preferably contains a wettability modifier. The wettability modifier refers to a component that modifies the wettability of the blood separation composition with the aqueous solution. Only one type of wettability modifier may be used, or two or more types may be used in combination.

[0109] Examples of the wettability modifier include surfactants and water-soluble polymers.

[0110] Examples of the surfactant include silicone surfactants, polysorbate 20, nonylphenyl polyethylene glycol, and sodium dodecyl sulfate.

[0111] Examples of the water-soluble polymer include polyoxyethylene polyoxypropylene glycol, dextrin, and collagen peptide.

[0112] The wettability modifier is preferably a surfactant, more preferably a nonionic surfactant, and even more preferably a silicone surfactant. The aqueous solution preferably contains a surfactant, more preferably a nonionic surfactant, and even more preferably a silicone surfactant. In this case, it becomes easier to adjust the rate of change A of the contact angle, and therefore the effects of the present invention can be more effectively exhibited.

[0113] The content of the wettability modifier in the aqueous solution (100 wt %) is preferably 0.0001 wt % or more, more preferably 0.001 wt % or more, even more preferably 0.007 wt % or more, and preferably 30 wt % or less, more preferably 10 wt % or less, even more preferably 5 wt % or less, even more preferably 1 wt % or less, even more preferably 0.5 wt % or less, and particularly preferably 0.1 wt % or less. When the content of the wettability modifier is equal to or greater than the lower limit and equal to or less than the upper limit, it becomes easier to adjust the rate of change A of the contact angle, and therefore the effects of the present invention can be more effectively exhibited. Furthermore, when the content of the wettability modifier is equal to or less than the upper limit, hemolysis can be effectively suppressed.

[0114] The content of the surfactant in the aqueous solution (100% by weight) is preferably 0.0001% by weight or more, more preferably 0.001% by weight or more, even more preferably 0.007% by weight or more, preferably 10% by weight or less, more preferably 5% by weight or less, even more preferably 1% by weight or less, even more preferably 0.5% by weight or less, and particularly preferably 0.1% by weight or less. When the content of the surfactant is equal to or greater than the lower limit and equal to or less than the upper limit, it becomes easier to adjust the rate of change A of the contact angle, and therefore the effects of the present invention can be more effectively exhibited. Furthermore, when the content of the surfactant is equal to or less than the upper limit, hemolysis can be effectively suppressed.

[0115] The content of the silicone surfactant in the aqueous solution (100% by weight) is preferably 0.0001% by weight or more, more preferably 0.001% by weight or more, even more preferably 0.007% by weight or more, and preferably 5% by weight or less, more preferably 1% by weight or less, and even more preferably 0.5% by weight or less. When the content of the silicone surfactant is above the lower limit and below the upper limit, it becomes easier to adjust the rate of change A of the contact angle, and therefore the effects of the present invention can be more effectively exerted. Furthermore, when the content of the silicone surfactant is below the upper limit, hemolysis can be effectively suppressed.

[0116] <Other ingredients> The aqueous solution may contain other components in addition to the above-mentioned components (anticoagulant, water, and wettability modifier). Examples of the other components include inorganic salts, sugars, pH adjusters, and sugar alcohols. Each of the other components may be used alone or in combination of two or more.

[0117] (Blood collection container body) The shape of the blood collection container body is not particularly limited. The blood collection container body is preferably a tubular container with a bottom. The blood collection container body preferably has an open end and a closed end. The open end of the blood collection container body is one end in the length direction of the blood collection container body, and the closed end of the blood collection container body is the other end in the length direction of the blood collection container body. In the blood collection container body, the distance between the open end and the closed end is the length of the blood collection container body.

[0118] The material of the blood collection container body is not particularly limited. Examples of materials for the blood collection container body include thermoplastic resins such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polymethyl methacrylate, and polyacrylonitrile; thermosetting resins such as unsaturated polyester resin, epoxy resin, and epoxy-acrylate resin; modified natural resins such as cellulose acetate, cellulose propionate, ethyl cellulose, and ethyl chitin; and glass such as silicate glass, such as soda-lime glass, phosphosilicate glass, and borosilicate glass, and quartz glass. The blood collection container body may be made of one material or two or more materials in combination.

[0119] The blood collection container body is preferably a resin container, more preferably a thermoplastic resin container, and even more preferably a polyethylene terephthalate container. When the blood collection container body is a resin container (particularly when it is a polyethylene terephthalate container), a relatively large amount of the blood separating composition is likely to adhere to unintended portions of the inner wall surface of the blood collection container body. In contrast, the blood collection container of the present invention can effectively exhibit the effects of the present invention even when the blood collection container body is a resin container. Furthermore, because the resin container is less likely to break than a glass container, when the blood collection container body is a resin container (particularly when it is a polyethylene terephthalate container), the risk of collected blood scattering due to breakage or the like can be reduced.

[0120] (stopper) The blood collection container preferably includes a stopper. The stopper is preferably attached to the open end of the blood collection container body. A conventionally known stopper can be used as the stopper. The stopper is preferably made of a material and has a shape that allows it to be attached to the open end of the blood collection container body in an airtight and liquid-tight manner. The stopper is preferably configured to be pierceable by a blood collection needle.

[0121] Examples of the stopper include a stopper having a shape that fits into the open end of the blood collection container body, a sheet-like seal stopper, and the like.

[0122] The stopper may be a stopper comprising a stopper body such as a rubber stopper and a cap member made of plastic, etc. In this case, the risk of blood coming into contact with the human body can be reduced when the stopper body is pulled out from the open end of the blood collection container body after blood collection.

[0123] Examples of materials for the stopper (or the stopper main body) include synthetic resin, elastomer, rubber, and metal foil. Examples of the rubber include butyl rubber and halogenated butyl rubber. Examples of the metal foil include aluminum foil. From the viewpoint of improving sealing performance, the stopper is preferably made of butyl rubber. The stopper (or the stopper main body) is preferably a butyl rubber stopper.

[0124] (Other details of blood collection container) The blood collection container is preferably a blood collection container that collects a predetermined amount of blood. The predetermined amount of blood is changed as appropriate depending on the size and internal pressure of the blood collection container. The predetermined amount of blood (the amount of blood collected in the blood collection container) may be 1 mL or more, 2 mL or more, 4 mL or more, 12 mL or less, 11 mL or less, or 10 mL or less.

[0125] In the blood collection container, preferably 3 mL or more, more preferably 4 mL or more, preferably 11 mL or less, and more preferably 10 mL or less of blood is collected per mL of the aqueous solution contained in the blood collection container body, so that the blood is not excessively diluted and the effects of the present invention can be more effectively achieved.

[0126] The aqueous solution is preferably contained in the blood collection container body at a position closer to the open end of the blood collection container body than the blood separation composition. The aqueous solution is preferably contained in the blood collection container body closer to the open end of the blood collection container body than the blood separation composition. The blood separation composition and the aqueous solution are preferably in contact when the blood collection container is in an upright position. The upright position refers to a state in which the closed end of the blood collection container body is located at the bottom and the open end of the blood collection container body is located at the top. The aqueous solution is preferably disposed on the upper surface of the blood separation composition.

[0127] The blood collection container is preferably a blood collection tube, and the blood collection container body is preferably a blood collection tube body.

[0128] The internal pressure of the blood collection container is not particularly limited. The internal pressure of the blood collection container is preferably reduced. When the blood collection container is a reduced-pressure container, a predetermined amount of blood can be easily collected into the blood collection container. The blood collection container can also be used as a vacuum blood collection tube, which is evacuated and then sealed with the stopper. When it is a vacuum blood collection tube, a predetermined amount of blood can be easily collected regardless of the skill level of the blood collector.

[0129] To prevent bacterial infection, the inside of the blood collection container is preferably sterilized in accordance with ISO or JIS standards. Conventional sterilization methods can be used. Examples of sterilization methods include radiation sterilization, such as gamma ray sterilization and electron beam sterilization, and high-pressure steam sterilization.

[0130] The blood collection container can be manufactured, for example, as follows.

[0131] An anticoagulant and a wettability modifier are dissolved in water to obtain an aqueous solution. If necessary, other components are also dissolved in water to obtain an aqueous solution. The obtained aqueous solution is added to the blood collection container body. Before or after adding the aqueous solution, the blood separation composition is placed in the blood collection container body.

[0132] FIG. 1 is a front cross-sectional view that schematically shows a blood collection container according to one embodiment of the present invention.

[0133] The blood collection container 1 shown in FIG. 1 comprises a blood collection container body 2, a blood separation composition 3, an aqueous solution 4, and a stopper 5. The blood separation composition 3 and the aqueous solution 4 are each contained within the blood collection container body 2. The blood collection container body 2 has an open end and a closed end. The blood separation composition 3 is contained in the bottom of the blood collection container body 2. The aqueous solution 4 contains an anticoagulant and water. The aqueous solution 4 is placed on the upper surface of the blood separation composition 3 when the blood collection container 1 is upright. The stopper 5 is inserted into the open end of the blood collection container body 2. The combination of the blood separation composition 3 and the aqueous solution 4 is such that the rate of change A of the contact angle is greater than the rate of change B of the contact angle.

[0134] FIG. 2 is a front cross-sectional view that schematically shows how blood is separated into plasma and blood cell components using the blood collection container shown in FIG.

[0135] The blood collection container 1 shown in Figure 2 is a blood collection container after blood has been collected in the blood collection container and centrifuged. By collecting blood in the blood collection container 1 and centrifuging it, blood cell components 9 are located below the partition formed by the blood separation composition 3, and plasma 8 is located above the partition formed by the blood separation composition 3.

[0136] (Plasma Separation Method) The blood collection container can be used to separate plasma from blood. A method for separating plasma according to the present invention includes the steps of collecting blood in the blood collection container and centrifuging the blood collection container containing the collected blood.

[0137] In the method for separating plasma according to the present invention, it is preferable to further include a step of mixing the collected blood with the aqueous solution between the step of collecting the blood and the step of centrifuging the blood. Examples of a method for mixing the collected blood with the aqueous solution include mixing by inversion.

[0138] The centrifugation conditions in the centrifugation step are not particularly limited as long as a partition can be formed using the blood separation composition to separate plasma from blood cells. Examples of the centrifugation conditions include centrifugation at 400 G or more and 4000 G or less for 10 minutes or more and 120 minutes or less.

[0139] After the centrifugal separation step, blood cell components are located below the partition formed by the blood separation composition, and plasma is located above the partition formed by the blood separation composition.

[0140] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0141] The following materials were prepared as the blood separation composition.

[0142] (Organic material that is fluid at 25°C) (Meth)acrylic resin (synthesized according to Synthesis Example 1 below) Petroleum-based resin (Eastman Chemical Company's "Rigalite S5090") Dicyclopentadiene resin 1 (Colon "Scolez SU500") Dicyclopentadiene resin 2 (Colon "Scolez SU90") Trimellitic acid ester

[0143] Synthesis example 1: 2-Ethylhexyl acrylate and butyl acrylate were radically polymerized by solution polymerization in the presence of an azo polymerization initiator to obtain a (meth)acrylic acid ester polymer ((meth)acrylic resin) having fluidity at 25° C. The specific gravity of the (meth)acrylic resin at 25° C. was 1.034.

[0144] (Inorganic fine powder) Hydrophilic silica (fine powder silica, Nippon Aerosil "200CF") Hydrophobic silica (fine powder silica, Nippon Aerosil "RX200") Calcium carbonate powder (specific gravity 2.7, IMERYS "Socal UP-G")

[0145] (Other ingredients) Silicone oil (Toray Dow Corning "SF8410") Organic gelling agent ("Gelall D" manufactured by New Japan Chemical Co., Ltd.) 1-Methyl-2-pyrrolidone (co-solvent)

[0146] The following materials were prepared for the aqueous solution:

[0147] (anticoagulant) Trisodium Citrate

[0148] (wettability modifier) Polysorbate 20 (Tween 20, Fujifilm Wako Pure Chemical Industries, Ltd. "Polyoxyethylene (20) Sorbitan Monolaurate") Silicone surfactant A (Dow-Toray "DOWSIL SF8410 Fluid") Silicone surfactant B ("KF-615A" manufactured by Shin-Etsu Chemical Co., Ltd.)

[0149] water

[0150] Example 1 Preparation of blood separation composition: A blood separation composition was prepared by mixing an organic component having fluidity at 25°C, an inorganic fine powder, and other components in the proportions shown in Table 1. A drop of the obtained blood separation composition was dropped successively into saline solutions at 25°C, each with a specific gravity adjusted in increments of 0.002, and the specific gravity was measured by floating or sinking in the saline solution. The specific gravity of the obtained blood separation composition at 25°C was 1.075.

[0151] Preparation of aqueous solution: An aqueous solution was obtained by mixing the components shown in Table 1 in the proportions shown in Table 1. The amounts in the table are pure amounts, and the content (concentration) of each component in the aqueous solution is the content (concentration) in an anhydrous state.

[0152] Preparation of blood collection containers: A tubular polyethylene terephthalate container (PET bottomed tube) with a length of 100 mm and an inner diameter of 14 mm at the open end was prepared as the blood collection container body. 1.2 g of the blood separation composition was placed in the bottom of the blood collection container body. 1 mL of the obtained aqueous solution was added to the surface of the blood separation composition. The pressure inside the blood collection container was reduced so that the blood collection volume was 8 mL, and the container was sealed with a butyl rubber stopper. After sealing, the container was irradiated with gamma rays at a dose of 15 kGy. In this way, a blood collection container was produced.

[0153] (Examples 2 and 3 and Comparative Example 1) An aqueous solution and a blood collection container were prepared in the same manner as in Example 1, except that the composition of the aqueous solution was changed as shown in Table 1.

[0154] Example 4 Preparation of blood separation composition: The organic component materials having fluidity at 25°C listed in Table 1 were blended, heated to 130°C, dissolved, and mixed to produce an organic component having fluidity at 25°C. Next, the organic component having fluidity at 25°C, inorganic fine powder, and other components were mixed in the blending ratios listed in Table 1 to produce a blood separation composition. Droplets of the obtained blood separation composition were successively dropped into saline solutions at 25°C, the specific gravity of which had been adjusted in steps of 0.002, and the specific gravity was measured by floating or sinking in the saline solution. The specific gravity of the obtained blood separation composition at 25°C was 1.045.

[0155] Preparation of aqueous solution: An aqueous solution was obtained by mixing the components shown in Table 1 in the proportions shown in Table 1. The amounts in the table are pure amounts, and the content (concentration) of each component in the aqueous solution is the content (concentration) in an anhydrous state.

[0156] Preparation of blood collection containers: A tubular polyethylene terephthalate container (PET bottomed tube) with a length of 100 mm and an inner diameter of 14 mm at the open end was prepared as the blood collection container body. 1.2 g of the blood separation composition was placed in the bottom of the blood collection container body. 1 mL of the obtained aqueous solution was added to the surface of the blood separation composition. The pressure inside the blood collection container was reduced so that the blood collection volume was 8 mL, and the container was sealed with a butyl rubber stopper. After sealing, the container was irradiated with gamma rays at a dose of 15 kGy. In this way, a blood collection container was produced.

[0157] (Example 5 and Comparative Example 2) An aqueous solution and a blood collection container were prepared in the same manner as in Example 4, except that the formulation of the aqueous solution was changed as shown in Table 1.

[0158] (evaluation) (1) Contact angle For the combination of the blood separation composition and aqueous solution used, the contact angle was measured using a contact angle measuring device ("DMo-502" manufactured by Kyowa Interface Science Co., Ltd.) as follows. At 25°C, 2 μL of the aqueous solution was dropped vertically onto the surface of the blood separation composition. Five seconds after the drop, the angle between the aqueous solution and the surface of the blood separation composition was measured using the θ / 2 method and defined as the contact angle (θ1) of the aqueous solution. 100 seconds after the drop, the angle between the aqueous solution and the surface of the blood separation composition was measured using the θ / 2 method and defined as the contact angle (θ2) of the aqueous solution. Similarly, at 25°C, 2 μL of the above-mentioned pure water was dropped vertically onto the surface of the blood separation composition. Five seconds after the drop, the angle between the pure water and the surface of the blood separation composition was measured using the θ / 2 method and defined as the contact angle (θ3) of the pure water. The angle formed between the pure water and the surface of the blood separating composition 100 seconds after dropping was measured by the θ / 2 method and was taken as the contact angle of pure water (θ4).

[0159] The rate of change A of the contact angle was calculated from the above formula (A), and the rate of change B of the contact angle was calculated from the above formula (B).

[0160] (2) The amount of blood separating composition adhering to unintended portions of the inner wall surface of the blood collection container body The obtained blood collection container was placed in a mix rotor ("MR-5" manufactured by AS ONE Corporation) and rocked for 2 hours at a rotation speed of 48 rpm. This rocking operation is a transport model operation that represents the harsh conditions under which blood collection containers are transported. Next, 8 mL of blood was collected into the blood collection container. The blood collection container into which the blood had been collected was centrifuged at 20°C and 1500 x g for 10 minutes. After centrifugation, blood cell components were located below the partition formed by the blood separation composition. Furthermore, a plasma layer was located above the partition formed by the blood separation composition.

[0161] The area R of the inner wall surface of the blood collection container body where the blood separating composition adhered to unintended areas was determined. The area R is the area of ​​the inner wall surface of the blood collection container body where the blood separating composition was present between the plasma layer and the blood collection container body in a direction perpendicular to the longitudinal direction of the blood collection container body (the radial direction of the blood collection container body). In addition, the area S of the inner wall surface of the blood collection container body where the plasma layer and the blood collection container body were in direct contact was determined. The adhesion area ratio X was calculated using the following formula (X):

[0162] Adhesion area ratio X (%) = [R / (R+S)] × 100 (X) R: Area R S: Area S

[0163] <Criteria for determining the amount of adhesion of the blood separating composition> ○○: Adhesion area ratio X is 0% or more and less than 25% ○: Adhesion area ratio X is 25% or more and less than 50% ×: Adhesion area ratio X is 50% or more

[0164] The configuration and results are shown in Table 1 below.

[0165] [Table 1] [Explanation of symbols]

[0166] 1...Blood collection container 2...Blood collection container body 3...Composition for blood separation 4...Aqueous solution 5…Bung body 8...Plasma 9…Blood cell components

Claims

1. A blood collection container body; a blood separating composition contained in the blood collection container body; an aqueous solution contained in the blood collection container body, the blood separating composition comprises an organic component having fluidity at 25°C and an inorganic fine powder; the organic component comprises a resin; the aqueous solution comprises an anticoagulant and water; The combination of the blood separating composition and the aqueous solution is a combination in which a rate of change A of the contact angle represented by the following formula (A) is greater than a rate of change B of the contact angle represented by the following formula (B): A blood collection container, wherein the absolute value of the difference between the rate of change A of the contact angle and the rate of change B of the contact angle is 5% or more. Contact angle change rate A (%) = [(θ1 - θ2) / θ1] × 100 (A) θ1: Contact angle (°) of the aqueous solution with the blood separating composition 5 seconds after 2 μL of the aqueous solution is dropped on the surface of the blood separating composition θ2: Contact angle (°) of the aqueous solution with the blood separating composition 100 seconds after 2 μL of the aqueous solution is dropped on the surface of the blood separating composition Contact angle change rate B (%) = [(θ3 - θ4) / θ3] × 100 (B) θ3: Contact angle (°) of pure water with the blood separating composition 5 seconds after 2 μL of pure water is dropped on the surface of the blood separating composition θ4: Contact angle (°) of pure water with the blood separating composition 100 seconds after 2 μL of pure water is dropped on the surface of the blood separating composition

2. 2. The blood collection container according to claim 1, wherein the absolute value of the difference between the rate of change A of the contact angle and the rate of change B of the contact angle is 30% or less.

3. 3. The blood collection container of claim 1, wherein the aqueous solution includes a wettability modifier.

4. 4. The blood collection container of claim 3, wherein the wettability modifier is a surfactant.

5. 4. The blood collection container of claim 3, wherein the wettability modifier is a silicone surfactant.

6. 3. The blood collection container according to claim 1, wherein the resin comprises a petroleum-based resin, a cyclopentadiene-based resin, a polyester-based resin, or a (meth)acrylic-based resin.

7. 3. The blood collection container according to claim 1, wherein the specific gravity of the blood separating composition at 25°C is 1.025 or more and 1.090 or less.

8. collecting blood in the blood collection container according to claim 1 or 2; and centrifuging the blood collection container in which the blood has been collected.

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