Microtome blades

Abstract

To provide a microtome blade which suppresses chipping, excels in sharpness and durability, and can cut well regardless of the hardness of a sample to be cut out. A microtome blade comprising a blade body having a flat base and a pointed portion 1B formed at the tip of the base, and a water-repellent DLC thin film 2 formed on the pointed portion 1B, wherein the contact angle of the water-repellent DLC thin film 2 with water is 90 degrees or more, the radius of curvature (R1) of the tip E of the pointed portion 1B is 15 nm or more and 150 nm or less, the radius of curvature (R2) of the tip F of the cutting edge including the water-repellent DLC thin film 2 is 30 nm or more and 250 nm or less, which is greater than the radius of curvature (R1) of the tip E of the pointed portion 1B, and the film thickness (d) of the water-repellent DLC thin film 2 is 15 nm or more and 150 nm or less.

Description

[Technical field]

[0001] The present invention relates to a blade for a microtome. [Background technology]

[0002] A microtome is a device for thinly slicing a material to prepare a sample for use in optical microscope observation, etc. In order to improve the sharpness and durability of the microtome blade, the surface of the blade is coated. For example, Patent Document 1 discloses a durable cutting blade in which the cutting edge is coated with a hard carbon film of about several μm by a PVD method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 02-041195 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, particularly in the fields of medicine and biology, a great number of extremely thin samples have been prepared each day using microtomes, creating a demand for improved cutting speed and further improvements in durability.

[0005] In order to reduce the frictional resistance of the blade surface and prevent the cut sample from sticking to the blade surface, the blade edge is given water repellency, but the durable cutting blade of Patent Document 1 does not have sufficient water repellency at the blade edge, and in order to collect thin samples without damaging them, it was necessary to further improve the water repellency. When cutting out samples as thin as a few micrometers, the sharpness and durability are insufficient, and there is a risk of variation in the film thickness of the cut sample, leaving room for improvement.

[0006] In addition, the objects cut using a microtome range from soft tissues such as kidneys, hearts, livers, lungs, brains, mammary glands, and fat to hard tissues such as bones, teeth, calcified lungs, and calcified kidneys, and there are also various methods for fixing them. However, when cutting hard samples using a microtome blade suitable for cutting soft samples, problems such as chipping and uneven thickness of the cut ultra-thin samples are likely to occur. Therefore, in the past, it was necessary to use microtome blades with different cutting edges to prevent chipping depending on the sample to be cut. Microtome blades suitable for cutting hard samples have a large cutting edge angle to prevent chipping (chipping) at the cutting edge. For example, the cutting edge angle of a microtome blade for soft samples is 22 degrees, while the cutting edge angle of a microtome blade used for cutting hard samples such as water-soluble resin blocks and frozen blocks is 35 degrees or 45 degrees. However, this was still not enough to prevent chipping, and there was a demand for microtome blades that were less susceptible to chipping.In addition, microtome blades suitable for cutting hard samples have a large cutting edge, and their sharpness tends to decrease when cutting soft samples, so improvements were needed.

[0007] The present invention has been made in consideration of the above circumstances, and has an object to provide a microtome blade that suppresses chipping, has excellent sharpness and durability, and can cut well, regardless of the hardness of the sample (object to be cut) being cut. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the following invention meets the above object, thereby completing the present invention.

[0009] <1> A microtome blade comprising: a blade body having a flat base and a pointed portion formed at the tip of the base; and a water-repellent DLC thin film formed on the pointed portion, wherein the water-repellent DLC thin film has a contact angle with water of 90 degrees or more, a radius of curvature (R1) of the tip of the pointed portion is 15 nm or more and 150 nm or less, a radius of curvature (R2) of the tip of the blade edge including the water-repellent DLC thin film is 30 nm or more and 250 nm or less and is larger than the radius of curvature (R1) of the tip of the pointed portion, and the thickness (d) of the water-repellent DLC thin film is 15 nm or more and 150 nm or less. <2> The blade angle θ is 15 to 50 degrees. <1> A blade for a microtome as described in . <3> The water-repellent DLC thin film contains fluorine and / or silicon. <1> or <2> A blade for a microtome as described in . <4> The blade body is made of a cemented carbide. <1> from <3> 2. A microtome blade according to any one of claims 1 to 11. <5> The content of the binder in the cemented carbide is 0% by mass or more and 24% by mass or less. <4> A blade for a microtome as described in . <6> The blade body is made of stainless steel. <1> from <3> 2. A microtome blade according to any one of claims 1 to 11. <7> The water-repellent thin film has a contact angle with water of 90 degrees or more and 135 degrees or less. <1> from <6> 2. A microtome blade according to any one of claims 1 to 11. <8> The water-repellent DLC thin film is a thin film in which the DLC film itself is given water repellency, or a thin film in which a water-repellent layer is formed on the surface of the DLC film. <1> from <7> 2. A microtome blade according to any one of claims 1 to 11. <9> The water-repellent layer is a water-repellent monolayer. <8> A blade for a microtome as described in . Effect of the Invention

[0010] According to the present invention, there is provided a microtome blade which suppresses chipping, has excellent sharpness and durability, and is capable of cutting well regardless of the hardness of the sample to be cut. [Brief description of the drawings]

[0011] [Figure 1] 1A and 1B are views of a blade according to an embodiment of the present invention, in which (A) shows the entire blade, and (B) shows an enlarged view of a part of the blade. [Diagram 2] 2 is a diagram showing the vicinity of the tip of the blade of the blade shown in FIG. 1. [Diagram 3] FIG. 13 is a diagram showing the vicinity of the tip of the blade of a blade body according to another embodiment. [Figure 4] FIG. 2 is a diagram for explaining the rake angle and clearance angle of the cutting tool shown in FIG. [Diagram 5] FIG. 13 is a top view illustrating the movement of a sliding microtome blade in the thin-section test of the embodiment. [Figure 6] 5 shows 500x magnified images of thin sections cut using the microtome blades of Example 1 and Comparative Example 1. (A) is an image of the thin section cut using Comparative Example 1, and (B) is an image of the thin section cut using Example 1. [Figure 7] 10A and 10B are views of a blade according to another embodiment of the present invention, in which (A) shows the entire blade, and (B) shows an enlarged view of a part of the blade. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The following is a detailed description of the embodiments of the present invention, but the following description of the constituent elements is one example (representative example) of the embodiment of the present invention, and the present invention is not limited to the following content as long as the gist of the present invention is not changed. Note that in this specification, when the expression "~" is used, it is used as an expression including the numerical value or physical property value before and after it.

[0013] [Microtome blade of the present invention] The microtome blade of the present invention (hereinafter sometimes referred to as "the microtome blade of the present invention") is a microtome blade comprising a blade body having a flat base and a pointed portion formed at the tip of the base, and a water-repellent DLC thin film formed on the pointed portion, in which the contact angle of the water-repellent DLC thin film with water is 90 degrees or more, the radius of curvature (R1) of the tip of the pointed portion is 15 nm or more and 150 nm or less, the radius of curvature (R2) of the tip of the blade edge including the water-repellent DLC thin film is 30 nm or more and 250 nm or less and is larger than the radius of curvature (R1) of the tip of the pointed portion, and the film thickness (d) of the water-repellent DLC thin film is 15 nm or more and 150 nm or less.

[0014] Here, the radius of curvature (R1) of the tip of the pointed portion and the radius of curvature (R2) of the tip of the blade including the water-repellent DLC thin film can be calculated from an image of the width-thickness cross section of the blade (cross section bc in FIG. 1) taken using an SEM. The radius of curvature (R1) of the tip of the pointed portion and the radius of curvature (R2) of the tip of the blade including the water-repellent DLC thin film are the average values ​​of the radii of curvature calculated at three points on the left, center, and right sides of the blade in the length direction. The film thickness (d) of the water-repellent DLC thin film is the distance from the tip of the pointed portion to the tip of the blade including the water-repellent DLC thin film, and is the value obtained by subtracting the radius of curvature (R1) of the tip of the pointed portion from the radius of curvature (R2) of the tip of the blade including the water-repellent DLC thin film. Details will be described later in the examples.

[0015] The microtome blade of the present invention has a water-repellent DLC thin film formed on the pointed portion of the blade body, with a contact angle with water of 90 degrees or more. This makes it easy to peel off the cut sample from the blade face, the sharpness does not change depending on the hardness of the cut sample, and the blade has excellent chipping resistance and durability.

[0016] The microtome blade of the present invention has a radius of curvature (R1) of the tip of the pointed portion of the blade body of 15 nm or more and 150 nm or less. If R1 is less than 15 nm, chipping is likely to occur, and scalpel scratches will occur in the cut sample. On the other hand, if R1 exceeds 150 nm, the cutting performance will be poor, the cutting load will be large, and the sample cannot be cut thinly at the level of several μm. R1 is preferably 30 nm or more, more preferably 50 nm or more, more preferably 60 nm or more, and even more preferably 70 nm or more. Also, R1 is preferably 130 nm or less, more preferably 120 nm or less, and even more preferably 110 nm or less.

[0017] The microtome blade of the present invention has a radius of curvature (R2) of the tip of the blade including the water-repellent DLC thin film of 30 nm or more and 250 nm or less, and is larger than the radius of curvature (R1) of the tip of the pointed portion. If R2 is less than 30 nm, chipping is likely to occur, and the water-repellent DLC thin film is likely to peel off. On the other hand, if R2 exceeds 250 nm, the cutting performance is poor, the cutting load is large, and the sample cannot be cut thinly at the level of several μm. R2 is preferably 50 nm or more, more preferably 60 nm or more, more preferably 75 nm or more, and even more preferably 90 nm or more. Also, R2 is preferably 200 nm or less, and more preferably 180 nm or less.

[0018] In the microtome blade of the present invention, the thickness (d) of the water-repellent DLC thin film is 15 nm or more and 150 nm or less. If d is less than 15 nm, it is difficult to form a uniform water-repellent DLC thin film, so that the cut sample is likely to have scalpel scratches, the hardness is insufficient, the water-repellent DLC thin film is likely to peel off due to friction, and the durability is low. On the other hand, if d is more than 150 nm, the cutting performance becomes poor, the water-repellent DLC thin film peels off in a cracking manner, and the durability is low. d is preferably 20 nm or more, more preferably 30 nm or more, more preferably 40 nm or more, and even more preferably 50 nm or more. Also, d is preferably 130 nm or less, more preferably 110 nm or less.

[0019] The microtome blade configuration of the present invention makes it possible to maintain cutting quality without being significantly affected by the hardness of the sample being cut, suppress chipping, and improve the lifespan of the blade.

[0020] The blade angle of the microtome blade of the present invention is appropriately selected depending on the type and purpose of the sample to be cut, but the blade angle θ is preferably 15 to 50 degrees, and more preferably 15 to 35 degrees. By setting the blade angle θ to 15 to 50 degrees, good cutting quality is achieved even when cutting a sample thinly.

[0021] The microtome blade of the present invention may have a blade body made of a cemented carbide alloy. By forming the blade body from a cemented carbide alloy, the phenomenon of the sample being wavy when sliced ​​can be suppressed.

[0022] The microtome blade of the present invention has a blade body made of a cemented carbide alloy, and the binder content in the cemented carbide alloy is preferably 0% by mass or more and 24% by mass or less. By using such a cemented carbide alloy, it is easy to precisely machine the blade body and to easily machine the tip of the pointed portion of the blade body into a desired shape.

[0023] From the viewpoint of adhesion between the blade body and the water-repellent DLC thin film, it is preferable that the cemented carbide constituting the blade body of the microtome blade of the present invention contains tungsten carbide (WC) and cobalt (Co), and that the cobalt content in the cemented carbide is 14 mass% or more.

[0024] In the microtome blade of the present invention, the contact angle of the water-repellent DLC thin film to water is preferably 90 degrees to 135 degrees, more preferably 95 degrees to 130 degrees, more preferably 100 degrees to 125 degrees, and even more preferably 105 degrees to 120 degrees. By having such a contact angle, the sample is less likely to stick to the blade surface, improving the sharpness of the blade.

[0025] In the microtome blade of the present invention, the contact angle of the water repellent thin film with respect to water is preferably from 90 degrees to 135 degrees, more preferably from 95 degrees to 130 degrees, more preferably from 100 degrees to 125 degrees, and even more preferably from 105 degrees to 120 degrees. R1 is 15 nm to 150 nm, preferably 30 nm to 145 nm, more preferably 40 nm to 140 nm, more preferably 50 nm to 130 nm, more preferably 60 nm to 120 nm, more preferably 70 nm to 110 nm, and even more preferably 75 nm to 100 nm. R2 is 30 nm to 250 nm, preferably 30 nm to 200 nm, more preferably 50 nm to 180 nm, more preferably 60 nm to 175 nm, more preferably 75 nm to 170 nm, further preferably 80 nm to 160 nm, and further preferably 90 nm to 150 nm; and d is from 15 nm to 150 nm, preferably from 20 nm to 130 nm, more preferably from 25 nm to 125 nm, more preferably from 30 nm to 120 nm, more preferably from 40 nm to 100 nm, and further preferably from 50 nm to 80 nm.

[0026] The objects (cut objects) cut out using the microtome blade of the present invention include kidneys, hearts, livers, lungs, brains, mammary glands, fat, bones, teeth, calcified lungs, calcified kidneys, etc. By adopting the configuration of the microtome blade of the present invention, it is possible to cut well regardless of the hardness of the object to be cut out. In addition, the microtome blade of the present invention can be used in both sliding and rotary cutting methods.

[0027] [Embodiment 1] Hereinafter, a blade according to an embodiment of the present invention will be described with reference to Fig. 1 to Fig. 3. Fig. 1 shows an overall view of a blade according to an embodiment of the present invention and a partially enlarged view of the blade. Fig. 2 shows the vicinity of the tip of the blade of the blade shown in Fig. 1. Fig. 3 shows the vicinity of the tip of the blade of a blade body of another embodiment.

[0028] As shown in Fig. 1, a blade 10 according to an embodiment of the present invention is a flat blade made of cemented carbide and has a straight cutting edge. The blade 10 is used as a replaceable blade for a microtome that slices a sample, such as bone or paraffin-embedded cell tissue, into extremely thin sections having a thickness on the order of micrometers to several tens of nanometers (for example, about 1 to 3 µm).

[0029] The blade body 1 of the blade 10 shown in Fig. 1 is formed with a blade length L of about 80 mm, a thickness t of about 0.25 mm, and a width W of about 8 mm. The blade body 1 has a base 1A with a width W1 of about 7.3 mm, and a pointed portion 1B formed from the base 1A to the tip with a width W2 of about 0.7 mm.

[0030] Both ends of the cutting edge of the blade body 1 are machined (chamfered) into a C-face with a triangular cutout. In this embodiment, the four corners are machined into a C-face. The C-face is formed by cutting out an isosceles triangle with equal sides of about 2 mm. The blade body 1 has a blade length L of about 80 mm, and even if a shear angle of 45° is applied to a workpiece (such as a thin-sectioned specimen) that is about 30 mm wide using a sliding microtome, the length is about 1 / cos45° (1.4114) times the length, which is about 42 mm, so the four corners of the blade 10 on which the C-face is formed are non-cutting portions.

[0031] The pointed portion 1B is formed in a tapered shape that gradually becomes thinner from the base portion 1A. In the shape of the pointed portion 1B shown in FIG. 1, the angle between the front and back surfaces of the pointed portion 1B is constant from the base portion 1A to the tip E of the blade. The shape of the pointed portion 1B is not limited to this, and it may be a multi-stage blade configuration having multiple regions between the base portion 1A and the tip E of the blade where the angles between the front and back surfaces of the pointed portion 1B are different. Furthermore, the pointed portion 1B has a symmetrical shape on the front and back, but may have an asymmetrical shape on the front and back.

[0032] As shown in FIG. 2, the tip E of the cutting edge of the pointed portion 1B is formed with a blade angle (blade edge angle) θ of 15 degrees to 50 degrees. The blade angle θ of the pointed portion 1B of the blade 10 is the angle (blade edge angle) that forms the tip E of the pointed portion 1B, and is the angle at the intersection point formed when the blade faces (blade surfaces) on both the front and back sides of the pointed portion 1B are extended. A smaller blade angle θ improves cutting quality, but shortens the lifespan because chipping is more likely to occur. On the other hand, if the blade angle θ is too large, the cutting quality deteriorates.

[0033] The blade angle θ is the angle between the rake face and the relief face of the blade when cutting a sample using the blade 10. As shown in FIG. 4, the relief angle β1 is the angle between the reference line H parallel to the direction in which the blade moves (cutting direction) and the relief face 12, and the relief angle β2 is the angle between the reference line V perpendicular to the direction in which the blade moves and the relief face 11, and the sum of the blade angle θ, the relief angle β1, and the relief angle β2 is 90 degrees. The relief angle β1 and the relief angle β2 are appropriately set according to the blade angle θ. For example, when cutting a sample using the blade 10 with a blade angle θ of 20 to 35 degrees, the relief angle β1 can be 10 degrees to 25 degrees, and the relief angle β2 can be 60 degrees to 30 degrees (β2=90 degrees-β1-θ).

[0034] The blade 10 has a water-repellent DLC thin film with high hardness, and is excellent in durability and ease of peeling off the cut sample, so that the cutting quality can be maintained even if the blade angle θ is increased compared to conventional microtome blades for soft samples, and by increasing the blade angle θ, chipping is less likely to occur even when cutting a hard sample. From these points of view, the shear angle of the microtome is also taken into consideration, but in order to maintain the cutting quality while suppressing chipping and improving the lifespan without being greatly affected by the hardness of the sample to be cut, the blade angle θ is preferably 15 degrees to 45 degrees, and more preferably 18 degrees to 40 degrees, 20 degrees to 35 degrees, 22 degrees to 34 degrees, 23 degrees to 33 degrees, 25 degrees to 31 degrees, 26 degrees to 30 degrees, or 27 degrees to 29 degrees.

[0035] 1 and 2, the shape of tip E of pointed portion 1B is a shape that is linearly inclined so as to approach each other from both sides of base portion 1A toward tip E of the cutting edge, but as shown in Fig. 3, pointed portion 1B may be shaped so as to curve from a straight line and connect to tip E of the cutting edge. In this case, the radius of curvature (R1) of tip E and the blade angle θ are as shown in Fig. 3.

[0036] The radius of curvature (R1) of the tip E of the pointed portion 1B is 15 nm to 150 nm.

[0037] 2, a water-repellent DLC thin film 2 is formed on the pointed portion 1B. The radius of curvature (R2) of the tip F of the blade tip including the water-repellent DLC thin film 2 is larger than the radius of curvature (R1) of the tip E of the pointed portion 1B, and is 30 nm to 250 nm. The thickness (d) of the water-repellent DLC thin film 2 is 15 nm to 150 nm.

[0038] (Carbide) The cemented carbide (hard metals, cemented carbide) forming the blade body 1 is a composite material in which metal particles made of carbides of metals in groups IVa, Va, and VIa of the periodic table are sintered with a binder made of iron-based metals such as Fe, Co, and Ni. The cemented carbide forming the blade body 1 is not particularly limited, and examples of the alloy that can be used include WC-Co alloys, WC-TiC-Co alloys, WC-TaC-Co alloys, WC-TiC-TaC-Co alloys, WC-Ni alloys, and WC-Ni-Cr alloys.

[0039] For example, a cemented carbide material containing WC and Co can be obtained by sintering a mixture containing WC particles and Co. The particle size of the WC particles can be various sizes, but from the viewpoint of preventing chipping during machining of the cutting edge tip, the particle size of the WC particles is preferably 0.1 μm to 0.7 μm, more preferably 0.3 μm to 0.7 μm. The "particle size" is the average particle size measured by the Sub Sieve Sizer method. The average particle size by the Sub Sieve Sizer method is calculated by passing air through a sample, measuring the flow rate and pressure drop to determine the specific surface area, and the particle size can be calculated. The Fischer method and the Blaine method can be used for the transmission method.

[0040] In addition, when the particle size of the WC particles used is larger than the diameter (R1×2) of the curvature circle of the tip E of the intended pointed portion 1B, the WC must be cut in order to make the tip E have the desired radius of curvature (R1). It is important that the cutting stress at that time is smaller than the bonding force with the Co that connects the WC. If the cutting stress becomes larger than this bonding force, the WC particles will peel off and the cutting edge will appear chipped. From the viewpoint of strength, the hard alloy material preferably has a hardness of 85 (HRC) or more, the flexural strength of the hard alloy material is preferably 3.0 GPa to 4.0 GPa, and the Young's modulus of the hard alloy material is preferably around 570 GPa.

[0041] Considering the balance between hardness, wear resistance, chipping resistance, adhesion of the water-repellent DLC thin film, and formability of the water-repellent DLC, the content of the binder in the cemented carbide is preferably 14 mass% to 30 mass%, more preferably 16 mass% to 27 mass%, more preferably 17 mass% to 25 mass%, more preferably 17 mass% to 24 mass%, and even more preferably 18 mass% to 22 mass%.

[0042] Among them, the cemented carbide forming the blade body 1 is preferably a cemented carbide containing WC and Co, and the content of cobalt in the cemented carbide is preferably 14% by mass or more. Here, it is generally believed that the water-repellent DLC thin film contains carbon atoms, and therefore has a high affinity with a substrate containing carbon atoms, and it has been commonly believed that the less the amount of Co (cobalt), called a binder, the easier it is for the cemented carbide to have a DLC coating. When the proportion of WC in the cemented carbide containing WC and Co is high, the alloy becomes harder, so that the blade can be made with less wear, and it is also considered to be preferable in terms of suppressing the waviness phenomenon of the cut sample. However, the inventors have discovered that when the proportion of WC is increased, the blade becomes more likely to chip, the adhesion of the water-repellent DLC thin film decreases and it becomes easier to peel off, and conversely, the adhesion of the water-repellent DLC thin film improves as the proportion of Co is increased. By setting the amount of Co in the cemented carbide containing WC and Co to a certain amount or more, the adhesion between the blade body and the water-repellent DLC thin film is improved, and chipping can be made less likely to occur.

[0043] The content of cobalt in the cemented carbide containing WC and Co is preferably 14 mass % or more, more preferably 16 mass % or more, more preferably 17 mass % or more, and even more preferably 18 mass % or more, in order to improve the adhesion of the water-repellent DLC thin film and the bonding strength between WC and Co.

[0044] On the other hand, if the proportion of WC is low, the material is susceptible to wear and is not suitable for blades, so the cobalt content in the cemented carbide is preferably 30 mass% or less, more preferably 27 mass% or less, more preferably 25 mass% or less, more preferably 24 mass% or less, and even more preferably 22 mass% or less.

[0045] Considering the balance between hardness, wear resistance, chipping resistance, adhesion of the water-repellent DLC thin film, and formability of the water-repellent DLC, the cobalt content in the cemented carbide is preferably 14 mass% to 30 mass%, more preferably 16 mass% to 27 mass%, more preferably 17 mass% to 25 mass%, more preferably 17 mass% to 24 mass%, and even more preferably 18 mass% to 22 mass%.

[0046] The cemented carbide of the blade body 1 is not limited to a composite material of a carbide of a metal of Groups IVa, Va, and VIa of the periodic table and a binder of an iron-based metal such as Fe, Co, or Ni, and may be made of a binderless material (binderless material) made by sintering a carbide of a metal of Groups IVa, Va, and VIa of the periodic table. Since the microtome blade of the present invention has a water-repellent DLC thin film of a specific thickness formed on the pointed portion, chipping can be suppressed even if the blade body is made of a binderless cemented carbide or a cemented carbide with a low binder ratio. From the viewpoint of ease of processing the tip shape of the pointed portion of the blade body, the content of the binder in the cemented carbide is preferably 0% to 24% by mass, more preferably 6% to 24% by mass.

[0047] Furthermore, the blade body 1 is not limited to being made of cemented carbide, but may be made of stainless steel or special steel.

[0048] (Water-repellent DLC thin film) Water-repellent DLC thin film 2 is a thin film that has been given water-repellency by incorporating fluorine or silicon into DLC. DLC is an abbreviation for Diamond-Like Carbon, and is an amorphous film whose main component is carbon that has the carbon-carbon bonds of both diamond and graphite.

[0049] The water contact angle of the water-repellent DLC thin film 2 is 90 degrees or more. The higher the water repellency, the less likely the cut sample will stick to the blade surface and the sharper the cutting performance will be, so the water contact angle of the water-repellent DLC thin film 2 is preferably 95 degrees or more, more preferably 100 degrees or more, and even more preferably 105 degrees or more. The "water contact angle" is the average value of the water contact angles measured at three points on the left, center, and right side in the length direction of the water-repellent DLC thin film 2 (the direction of arrow a in Figure 1).

[0050] There is no particular upper limit to the contact angle of the water-repellent DLC thin film 2 with respect to water, but taking into consideration productivity and the like, it can be, for example, 135 degrees or less, 130 degrees or less, 125 degrees or less, or 120 degrees or less.

[0051] The water-repellent DLC thin film 2 is formed on the pointed portion 1B. The water-repellent DLC thin film 2 may be formed at least on the tip E side of the pointed portion 1B (for example, a 1 μm to 20 μm region including the tip E of the pointed portion 1B), but it is preferably formed on the entire pointed portion 1B so that the cut sample does not easily stick to the pointed portion 1B and can be easily peeled off.

[0052] [Embodiment 2] The microtome blade 30 shown in FIG. 7 is made of cemented carbide and has a two-stage blade. The blade body 3 of the blade 30 has a base 3A and a pointed portion 3B. The pointed portion 3B has a first region A1 including the tip of the blade and a second region A2 continuing from the first region A1 to the base 3A, which is a third region A3. The second region A2 is wider than the first region A1. The water-repellent DLC thin film (not shown) formed on the pointed portion 3B of the blade body 3 of the blade 30 has a DLC thin film and a water-repellent layer formed on the surface of the DLC thin film, and has a film thickness (d) (i.e., the total thickness of the DLC thin film and the water-repellent layer) of 15 nm to 150 nm. The water-repellent layer constituting the water-repellent DLC thin film of the blade 30 is a water-repellent coating layer formed by coating with a water-repellent coating agent. For example, the water-repellent layer can be a fluorine-based monomolecular film having a thickness of about 10 nm that is coated with a fluorine-based coating agent, but the water-repellent layer is not limited to this.

[0053] The blade 30 is similar to the blade 10, except for the shape of the blade body and the configuration of the water-repellent DLC thin film. The contact angle of the water of the water-repellent DLC thin film of the blade 30, the radius of curvature (R1) of the tip of the pointed portion, the radius of curvature (R2) of the tip of the cutting edge, the film thickness (d) of the water-repellent DLC thin film, and the blade angle θ are similar to those of the blade 10, and the preferred ranges are also similar.

[0054] The water-repellent DLC thin film is not particularly limited as long as it has an amorphous structure containing carbon and the surface of the thin film has water-repellency, but preferably contains carbon, fluorine and / or silicon. The thin film may contain fluorine or silicon throughout, or only the surface of the DLC thin film may be modified with fluorine or silicon to be water-repellent.

[0055] Specifically, the water-repellent DLC thin film constituting the microtome blade of the present invention includes a thin film in which the DLC film itself is given water repellency, or a thin film in which a water-repellent layer is formed on the surface of the DLC film. An example of a thin film in which the DLC film itself is given water repellency is a thin film in which the DLC film itself contains fluorine, silicon, or the like. Also, an example of a thin film in which a water-repellent layer is formed on the surface of a DLC film that is not given water repellency is a thin film in which a water-repellent layer is formed on the surface of a thin film in which the DLC film itself is given water repellency. An example of the water-repellent layer is a water-repellent monolayer.

[0056] (Method of Manufacturing Microtome Blade of the Present Invention) The microtome blade of the present invention can be manufactured, for example, by forming a water-repellent DLC film on the cutting edge side of the pointed portion of a blade body made of cemented carbide or stainless steel. There are no particular limitations on the method for forming the DLC thin film, and known methods can be used, such as plasma CVD, pulsed plasma CVD, and thermal electron impact ionization deposition using a hydrocarbon gas as a carbon source, and arc ion plating, magnetron sputtering, and ion beam sputtering using solid carbon (graphite) as a carbon source.

[0057] For example, by using a hydrocarbon gas containing fluorine or silicon, it is possible to form a water-repellent DLC film that contains fluorine or silicon throughout the entire DLC film.

[0058] In addition, a water-repellent DLC thin film having a water-repellent layer on its surface can be formed, for example, by forming a DLC thin film or a DLC thin film containing fluorine or silicon, and then dipping it in a fluorine-based water-repellent coating agent.

[0059] Furthermore, when the tip of the blade is sharpened as in the blade body 1 (i.e., the radius of curvature R1 of the tip E is set to a predetermined thickness), deposition by the PVD method (physical vapor deposition method) may cause chipping due to damage to the blade tip, making the deposition conditions and control more complicated. By using the CVD method, it is easy to deposit a water-repellent DLC thin film while reducing damage to the blade tip, so the CVD method is one of the preferred deposition methods for DLC thin films. EXAMPLES

[0060] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples unless the gist of the present invention is changed.

[0061] [evaluation] (Measurement of contact angle with water) The contact angle of the blade edge of the blade coated with the water-repellent DLC thin film of this embodiment and the comparative microtome blade with respect to water was measured using NICK's LSE100T. At three points on the length direction of the blade edge of each blade, namely the left side (position 10 mm from the left end of the blade), the center (position 40 mm from the left end of the blade), and the right side (position 70 mm from the left end of the blade), 0.01 to 0.12 μL of pure water was dropped onto the blade edge at room temperature, and the contact angle (static contact angle) was measured about 1000 ms later according to the θ / 2 method, and the average value of these three points was taken as the contact angle with respect to water.

[0062] (Thin section test) The microtome blade manufactured under the conditions of this example was attached to a microtome and a thin-slicing test was performed. As shown in Fig. 5, the microtome used was a sliding microtome in which the tip of a blade attached to a holder (not shown) was positioned at a predetermined angle (α was set to 27.5° in this example) with respect to a reference line L11, and the blade was moved back and forth in a direction perpendicular to the reference line L11 to slice the workpiece into sections. A mark M (see Fig. 5) was provided on one end of the microtome blade to distinguish between the front and back. During the thin-slicing test, the blade tip is inclined relative to the reference line L11, and the workpiece moves back and forth in the direction perpendicular to the reference line L11, so that the position where the blade tip first hits the workpiece remains the same. A mark line was provided in the width direction so that when the blade was removed and then reattached, the workpiece would be in the same position as the initial position.

[0063] (Adhesion evaluation) The cutting waste produced when cutting a pig's femur with a saw was degreased with ethanol and then dried. Pieces smaller than 1 mm (selected to be around 0.5 mm in diameter) were grasped with tweezers and embedded into the internal organs to be embedded, and the embedding process was performed. These were used as the cut pieces. Using the prepared cut object, a thin-slicing test was repeatedly performed with a thickness of 2 μm to 4 μm using the method described in the thin-slicing test above. When the water-repellent DLC thin film on the cutting edge peels off, the thin-sliced ​​product will no longer curl, so the curling state of the thin-sliced ​​product was checked for the first and 20th times and used as an evaluation of adhesion. Adhesion was evaluated according to the following criteria. ○: Curls at a diameter of 1 mm or less. △: No curl, or the entire slice curls but the curl diameter is large (2mm or more) ×: Not cut

[0064] (Sharpness rating) Using paraffin-embedded samples of pig stomach, brain, kidney, liver, and lung, 500 sections were each cut using the method described in the thin section test above, and the curling condition of each cut section was checked and evaluated according to the following criteria. ○: Curls at a diameter of 1 mm or less. △: No curl, or the entire slice curls but the curl diameter is large (2mm or more) ×: Not cut

[0065] (chipping evaluation) The thin-section test was carried out in the same manner as the sharpness evaluation, and the first time (initial performance) was checked, and thereafter the presence or absence of scalpel scratches on the thin-section sample was checked every 100 times. If scalpel scratches were found on the thin-section sample, the test was stopped temporarily and the microtome blade was checked. The area of ​​the microtome blade that was thought to be the cause of the scalpel scratches was observed under a microscope with a magnification of 500 to 2500 times to confirm the depth and width of the chipping and evaluate it according to the following criteria. ○: Less than 2 μm in both depth and width △: Depth and width are both 2μm or more ×: Not cut

[0066] (Measurement of R1, R2, d of microtome blade) The cutting edge of the microtome blade of this example was observed at a magnification of 20,000 times using an electron microscope (ELIONIX Corporation, electron beam cutting edge analysis device ERA-8900) to observe the surface condition. Using the blade body before the water-repellent DLC thin film was formed, the radius of curvature (R1) of the tip E was measured at three points along the length of the blade edge: the left side (10 mm from the left end of the blade), the center (40 mm from the left end of the blade), and the right side (70 mm from the left end of the blade), and the average was calculated. Next, a water-repellent DLC thin film was formed on the blade body, and then the radius of curvature (R2) of the tip F was measured at three points along the length of the blade: the left side (10 mm from the left end of the blade), the center (40 mm from the left end of the blade), and the right side (70 mm from the left end of the blade), and the average was calculated. The thickness (d) of the water-repellent DLC thin film was calculated by calculating the difference between the radius of curvature (R2) of tip F and the radius of curvature (R1) of tip E at each of the above three points and averaging them.

[0067] <Comparative Example 1> The blade body, made of the following material and shape, was placed in the chamber of a plasma CVD deposition device, and a DLC thin film was formed.The blade was then dipped in a fluorine-based water-repellent coating agent to form a water-repellent monolayer, forming a water-repellent DLC thin film containing carbon and fluorine. Blade body: WC-Co alloy (Co content 19% by mass) Blade length L: 80mm Thickness: 0.25mm ·Width W: 8mm, Width W1: 7.3mm, Width W2: 0.7mm Blade angle θ: 28 degrees Radius of curvature of the pointed tip E (R1): 40 nm

[0068] When the cutting edge after the water-repellent DLC film was formed was observed with an optical microscope, it was found that the water-repellent DLC film was highly uneven, and there was particularly large variation in the condition of the film at the tip of the cutting edge (ridge line), and the film thickness (d) of the formed film was thicker than 150 nm.

[0069] <Example 1> The blade body similar to that of Comparative Example 1 was installed in the chamber of a plasma CVD deposition apparatus, and a DLC thin film was formed. Next, the blade was dipped in a fluorine-based water-repellent coating agent to form a water-repellent monolayer, and a water-repellent DLC thin film containing carbon and fluorine was formed. The radius of curvature (R2) of the tip F of the blade including the water-repellent DLC thin film produced was 150 nm.

[0070] When the blade tip after the water-repellent DLC thin film was formed was observed with an optical microscope, it was found that the water-repellent DLC thin film on the microtome blade of Example 1 had almost no irregularities and was formed uniformly.

[0071] When the contact angles of the cutting edge of the microtome blade of Example 1 with water were measured, they were 116.1 degrees on the left side, 120.1 degrees in the center, 116.3 degrees on the right side, and an average of 117.5 degrees.

[0072] (Thin slice test 1) Fig. 6 is a 500x magnified image of tissue obtained by attaching the manufactured blade to a sliding microtome and cutting an object in which pig liver cells are embedded into a thickness of 2 µm. Fig. 6(A) is an image of a thin section cut using the microtome blade of Comparative Example 1, and Fig. 6(B) is an image of a thin section cut using the microtome blade of Example 1. When the microtome blade of Comparative Example 1 was used, scalpel scratches were generated, but when the microtome blade of Example 1 was used, the generation of scalpel scratches was suppressed, and a good sample was obtained.

[0073] (Thin slice test 2) A thin-slicing test was carried out using the microtome blade of Example 1. Before cutting out the bone to be cut, the bone was sliced ​​10 times at 2 μm using paraffin as the object to be cut. After slicing the bone 90 times, the bone was sliced ​​2 μm using paraffin as the object to be cut. For comparison, a similar experiment was conducted using a fluororesin-coated microtome blade (steel blade, blade body: stainless steel, R2: approximately 25 nm, blade angle: 35 degrees, contact angle of coating film with water (average of three points): 88.6 degrees). The results are shown in Table 1. As shown in Table 1, it can be seen that the microtome blade of Example 1 provided thin sections with a more stable thickness than the comparative example.

[0074] [Table 1]

[0075] (Thin slice test 3) Using the microtome blade of Example 1, a thin-section test was conducted on a human lung as a cut object, following the procedures of an ethical committee, etc. Human lungs are one of the cut objects that are prone to chipping, as they are densely packed with blood vessels and contain many calcified blood vessels. The comparative steel blade was used in three separate positions, and was replaced 50 times at each position, for a total of 150 times, whereas the microtome blade of Example 1 was able to slice more than 660 times at one position without any problems.

[0076] <Examples 2 and 3> The blade body was made of a WC-Co alloy with a Co content of 12% or 19% by mass and had the same shape as in Example 1. Blades with a curvature radius (R2) of the tip F including a water-repellent DLC thin film of 120 μm and 140 μm were manufactured in the same manner as in Example 1 except that the film formation conditions were changed.

[0077] Table 2 shows the results of the evaluation of the adhesion of the water-repellent DLC thin film.

[0078] [Table 2]

[0079] A blade body having the following material and shape was used, and attached to a plasma CVD deposition apparatus. A water-repellent DLC thin film having the thickness shown in Table 3 was deposited in the same manner as in Example 1, except that the deposition conditions were changed. Blade body: WC-Co alloy (Co content 24% by mass) Blade length L: 80mm Thickness: 0.25mm ·Width W: 8mm, Width W1: 7.3mm, Width W2: 0.7mm Blade angle θ: 20°~35° Table 3 shows the results of evaluating the adhesion, sharpness, and chipping of the manufactured blades.

[0080] [Table 3] [Industrial Applicability]

[0081] The microtome blade of the present invention can be attached to a microtome used for slicing various tissues, and is therefore industrially useful. [Explanation of symbols]

[0082] 1, 3 Blade body 11. Scooping surface 12 Flank 1A, 3A base 1B, 3B Pointed part 2. Water-repellent DLC thin film 10, 30 Knives A1 First Area A2 Second Area A3 The third area E, F tip R1 Radius of curvature of tip E R2 Radius of curvature of tip F d Film thickness t Thickness of the blade body θ Tool angle L Blade length W,W1,W2 width V,H reference line

Claims

1. A blade body having a flat base and a pointed portion formed at a tip of the base; A water-repellent DLC thin film formed on the pointed portion. The water-repellent DLC thin film has a contact angle with water of 90 degrees or more; The radius of curvature (R1) of the tip of the pointed portion is 15 nm or more and 150 nm or less, the radius of curvature (R2) of the tip of the blade tip including the water-repellent DLC thin film is 30 nm or more and 250 nm or less, and is larger than the radius of curvature (R1) of the tip of the pointed portion; A microtome blade, wherein the water-repellent DLC thin film has a thickness (d) of 15 nm or more and 150 nm or less.

2. 2. The microtome blade according to claim 1, wherein the blade angle θ is 15 to 50 degrees.

3. The microtome blade according to claim 1 or 2, wherein the water-repellent DLC thin film contains fluorine and / or silicon.

4. 3. The microtome blade according to claim 1, wherein the blade body is made of a cemented carbide alloy.

5. The microtome blade according to claim 4 , wherein the content of the binder in the cemented carbide is from 0% by mass to 24% by mass.

6. 3. The microtome blade according to claim 1, wherein the blade body is made of stainless steel.

7. 3. The microtome blade according to claim 1, wherein the water-repellent DLC thin film has a contact angle with water of 90 degrees or more and 135 degrees or less.

8. 3. The microtome blade according to claim 1, wherein the water-repellent DLC thin film is a thin film in which the DLC film itself is given water-repellency, or a thin film in which a water-repellent layer is formed on the surface of the DLC film.

9. 9. The microtome blade of claim 8, wherein the water-repellent layer is a water-repellent monolayer.

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