Mill blank assembly

Abstract

The purpose of the present invention is to make it possible to further reduce the risk of fracture of a part to be processed, while maintaining appropriate adhesive force between the part to be processed and a holding part.　A mill blank assembly (10) has a part to be processed (20), a holding part (30) for holding the part to be processed (20), and an adhesive layer (40). The adhesive layer (40) is disposed between a first adhesive surface (21) and a second adhesive surface (33), which are adhesive surfaces of the part to be processed (20) and the holding part (30), and bonds the part to be processed (20) and the holding part (30). The second adhesive surface (33) of the holding part (30) has an uneven structure (36) including a convex part (34) and a concave part (35), and the convex part (35) and the concave part (36) are not fitted to each other.

Description

Mill Blank Assembly

[0001] The present disclosure relates to a mill blank assembly.

[0002] Mill blank assemblies used in prosthetic treatments, such as crown treatment and implant treatment, that repair missing teeth with artificial materials (prostheses), have been known. Mill blank assemblies have been disclosed that include a workpiece and a holder for the workpiece, with one of the bonding surfaces of the workpiece and the holder having a protrusion and the other having a recess for receiving the protrusion (see, for example, Patent Documents 1 to 3).

[0003] These conventional mill blank assemblies have a structure in which a recess and a protrusion fit together, which makes them susceptible to internal stress caused by differences in thermal contraction or expansion between the processed part and the holding part, and there is a risk of the processed part breaking due to temperature changes or even vibrations during transportation.

[0004] JP 2004-507316 A JP 2020-99600 A JP 2021-115274 A

[0005] The present disclosure has been made in consideration of the above circumstances, and makes it possible to further reduce the risk of breakage of the processed portion while maintaining an appropriate adhesive force between the processed portion and the holding portion.

[0006] In order to achieve the above object, the mill blank assembly according to the present disclosure includes a workpiece, a holding part that holds the workpiece, and an adhesive layer that is disposed between the adhesive surfaces of the workpiece and the holding part and that bonds the workpiece and the holding part. At least one of the adhesive surfaces of the workpiece and the holding part has an uneven structure consisting of protrusions and recesses, and the protrusions and recesses do not fit together.

[0007] According to the present disclosure, it is possible to further reduce the risk of breakage of the processed portion while maintaining an appropriate adhesive strength between the processed portion and the holding portion.

[0008] 1. A side view of a mill blank assembly according to the first embodiment, Examples 1 to 5, and Examples 27 to 36 of the present disclosure. It is a perspective view of the retaining portion shown in FIG. 1. It is a plan view of the retaining portion shown in FIG. 1. It is a cross-sectional view along line A-A of FIG. 3, with the workpiece and adhesive layer added by dashed lines. It is a perspective view of a retaining portion in a mill blank assembly according to the second embodiment and Example 6 of the present disclosure. It is a plan view of the retaining portion shown in FIG. 5. It is a cross-sectional view along line B-B of FIG. 6. It is a perspective view of a retaining portion in a mill blank assembly according to the third embodiment, Examples 7, 8, 10 to 12, 15 to 17, 24 to 26, 37, and 40 of the present disclosure. It is a plan view of the retaining portion shown in FIG. 8. It is a cross-sectional view along line C-C of FIG. 9. It is a perspective view of a retaining portion in a mill blank assembly according to the fourth embodiment and Example 9 of the present disclosure. It is a plan view of the retaining portion shown in FIG. 11. It is a cross-sectional view along line D-D of FIG. 12. It is a cross-sectional view along line E-E of FIG. It is a perspective view of a retaining portion in a mill blank assembly according to the fifth embodiment, Examples 13, and 14 of the present disclosure. 15. A plan view of the retaining portion shown in FIG. 15. A cross-sectional view taken along line F-F in FIG. 16. A perspective view of the retaining portion in a mill blank assembly according to the sixth embodiment, the seventh embodiment, and Examples 18 and 19 of the present disclosure. A bottom view of the machined portion in a mill blank assembly according to the sixth embodiment and Example 18 of the present disclosure, as viewed from the first adhesive surface side. A cross-sectional view taken along line G-G in FIG. 19. A bottom view of the machined portion in a mill blank assembly according to the seventh embodiment and Example 19 of the present disclosure, as viewed from the first adhesive surface side. A cross-sectional view taken along line H-H in FIG. 21. A perspective view of the retaining portion in a mill blank assembly according to the eighth embodiment and Examples 38 and 39 of the present disclosure. A perspective view of the retaining portion in a mill blank assembly according to the ninth embodiment, Examples 20 and 21 of the present disclosure. A perspective view of the retaining portion in a mill blank assembly according to the tenth embodiment, Examples 22 and 23 of the present disclosure. An exploded perspective view and an exploded side view of the machined portion and retaining portion of a mill blank assembly according to Comparative Example 1. An exploded perspective view and an exploded side view of the machined portion and retaining portion of a mill blank assembly according to Comparative Example 2.

[0009] First Embodiment A mill blank assembly according to one embodiment of the present disclosure will be described below with reference to FIGS. 1 to 4 . The mill blank assembly according to this embodiment is a "dental mill blank assembly" used for dental applications. The mill blank assembly according to this embodiment is attached to, for example, a chuck device of a known dental processing device such as a CAD / CAM processing device, and is machined by a cutting tool into a dental prosthesis such as a crown, bridge, inlay, veneer, or implant. Note that the dental processing device is not limited to a CAD / CAM processing device and may be other processing device, or may include a cutting device, a coloring device, a baking device, a polishing device, or the like. Furthermore, the mill blank assembly of the present disclosure is not limited to dental applications and may be used for other applications.

[0010] 1 , the mill blank assembly 10 according to this embodiment includes a workpiece 20, a holding portion 30, and an adhesive layer 40. The workpiece 20 and the holding portion 30 have adhesive surfaces that are bonded to each other. More specifically, the workpiece 20 has a first adhesive surface 21, and the holding portion 30 has a second adhesive surface 33. The adhesive layer 40 is disposed between the first adhesive surface 21 and the second adhesive surface 33, and bonds the workpiece 20 and the holding portion 30 together.

[0011] Furthermore, in the mill blank assembly 10 according to this embodiment, the second adhesive surface 33 of the holding portion 30 has a concave-convex structure 36 consisting of convex portions 34 and concave portions 35, and the first adhesive surface 21 of the workpiece 20 is flat. Note that the concave-convex structure 36 is not limited to being provided only on the second adhesive surface 33, but may be provided only on the first adhesive surface 21 (e.g., the sixth and seventh embodiments described below), or may be provided on both the first adhesive surface 21 and the second adhesive surface 33. When the concave-convex structure 24 (see FIGS. 19 and 21 ) and the concave-convex structure 36 are provided on both the first adhesive surface 21 and the second adhesive surface 33, the concave-convex structure 24 consisting of convex portions 22 and concave portions 23 on the first adhesive surface 21 of the workpiece 20 and the concave-convex structure 36 consisting of convex portions 34 and concave portions 35 on the second adhesive surface 33 of the holding portion 30 do not fit together.

[0012] The workpiece 20 is machined into a dental prosthesis such as a crown, bridge, inlay, veneer, or implant. The workpiece 20 in Example 1 is made of a substantially cubic block. However, the workpiece 20 of the present disclosure is not limited to the shape of Example 1, and may be a substantially rectangular block or a cylindrical block that is elongated along the axial direction of the support portion 32 of the holding portion 30, or may have any other known shape.

[0013] The material of the workpiece 20 is not particularly limited as long as it is a dental material. For example, the workpiece 20 is preferably made of a material containing oxide ceramics, or a composite material containing acrylic resin, polymer resin, and inorganic filler. Furthermore, the workpiece 20 is more preferably made of a material containing at least one selected from the group consisting of zirconia, alumina, and glass ceramics, because of its excellent biocompatibility, aesthetics, and strength. Furthermore, among these, the workpiece 20 is most preferably made of a material containing zirconia (more preferably, a zirconia calcined body), because of its high biocompatibility, strength, and aesthetics.

[0014] The workpiece 20 has a first adhesive surface 21 on one side thereof that is bonded to the holding part 30. The first adhesive surface 21 in this embodiment is flat. Furthermore, the first adhesive surface 21 in this embodiment may be flat, i.e., flat, in the range in which the arithmetic mean roughness Ra defined in JIS B0601:2013 is 0.2 μm or less, or may be smooth or have fine irregularities.

[0015] The Vickers hardness of the workpiece 20 is preferably 40 HV 5 / 30 or more, more preferably 60 HV 5 / 30 or more, even more preferably 65 HV 5 / 30 or more, and most preferably 70 HV 5 / 30 or more. The workpiece 20 having such a Vickers hardness is suitable for processing with a CAD / CAM processing machine and is preferable in that it has sufficient mechanical strength for use as a dental prosthesis.

[0016] On the other hand, the upper limit of the Vickers hardness is preferably 140 HV 5 / 30 or less, more preferably 135 HV 5 / 30 or less, even more preferably 130 HV 5 / 30 or less, and most preferably 125 HV 5 / 30 or less. A workpiece 20 having such a Vickers hardness is suitable for processing with a CAD / CAM processing machine and is preferable in that it has sufficient mechanical strength as a dental prosthesis. The Vickers hardness is measured, for example, by the procedure described in the Examples below.

[0017] If the sample cracks or the indentation is chipped at HV 5 / 30, HV 1 / 10 may be used instead. Even in this case, the Vickers hardness of the workpiece 20 is preferably 40 HV 1 / 10 or more, more preferably 60 HV 1 / 10 or more, even more preferably 65 HV 1 / 10 or more, and most preferably 70 HV 1 / 10 or more. The upper limit of the Vickers hardness is preferably 140 HV 1 / 10 or less, more preferably 135 HV 1 / 10 or less, even more preferably 130 HV 1 / 10 or less, and most preferably 125 HV 1 / 10 or less.

[0018] Furthermore, the workpiece 20 preferably has a three-point bending strength measured in accordance with ISO 6872: 2015 of 10 MPa to 100 MPa, more preferably 15 to 90 MPa, and most preferably 20 to 80 MPa. By setting the three-point bending strength within this range, the workpiece 20 has a reduced risk of fracture due to temperature changes or vibration, good machinability and grindability when processed into a dental prosthesis, and high durability after processing, making it suitable for dental applications.

[0019] The holding part 30 is a member that holds the workpiece 20, and is attached to a chuck device of the dental processing device while holding the workpiece 20. The holding part 30 includes a base 31 and a support part 32.

[0020] The material of the holder 30 is not particularly limited, but from the viewpoints of strength, durability, cost, formability, etc., it is desirable that the holder 30 be made of a material containing at least one of metals such as aluminum and iron, and alloys such as aluminum alloys and iron alloys. Among these, from the viewpoint of suppressing thermal expansion and thermal contraction, it is most desirable that the holder 30 be made of an aluminum alloy or an iron alloy. The base 31 and the support 32 can be made using these materials and connected in advance, or they can be made separately and connected by welding, adhesive, etc.

[0021] The base 31 of this embodiment is formed in a plate shape and, as shown in FIGS. 2 and 3 , has a shape (approximately oval shape) in which both sides of a disk are cut out by two parallel straight lines, and has a pair of arcuate edges 31 a and a pair of parallel straight edges 31 b. The base 31 has, on one side, the second adhesive surface 33, which is bonded to the workpiece 20. Therefore, the second adhesive surface 33 of this embodiment is surrounded by the pair of arcuate edges 31 a and the pair of straight edges 31 b, and has a shape that is line-symmetrical with respect to a line segment that passes through the center O of the arcuate edges 31 a and is perpendicular to and parallel to the straight edges 31 b. Furthermore, the second adhesive surface 33 of this embodiment also has a shape that is point-symmetrical with respect to the center O. The center O coincides with the central axis of the support portion 32 and the central axis of the mill blank assembly 10. The base 31 has a substantially cylindrical base 31c on the side opposite the second adhesive surface 33, and a first notch 31d is provided on the side of the base 31c. The first notch 31d functions as a positioning portion or the like for determining the attachment direction of the holding portion 30 to the chuck device.

[0022] The second adhesive surface 33 has a concave-convex structure 36 consisting of circular convex portions 34 and annular concave portions 35. The convex portions 34 and concave portions 35 of the concave-convex structure 36 are configured so as not to fit together. Note that, in this disclosure, "fit" not only refers to the convex portions and concave portions fitting together with almost no gaps, i.e., fitting, but also refers to the convex portions and concave portions fitting together with some gaps between them, i.e., loose fitting. Therefore, in this disclosure, the "non-fitting configuration" includes not only the convex portions 34 and concave portions 35 on the second adhesive surface 33 of the holding portion 30 not fitting together, in other words, not fitting together, but also not loose fitting. The "non-fitting configuration" also includes not only the convex portions 34 and concave portions 35 not fitting together, but also the entire areas of the first adhesive surface 21 of the workpiece 20 and the second adhesive surface 33 of the holding portion 30 not fitting together. Furthermore, when uneven structures 24, 36 are provided on both the first adhesive surface 21 of the workpiece 20 and the second adhesive surface 33 of the holding portion 30, the "configuration that does not fit into each other" also includes a case in which the uneven structure 24 consisting of convex portions 22 and concave portions 23 provided on the workpiece 20 (see the sixth and seventh embodiments, Figures 19 and 21, etc. described below) and the uneven structure 36 consisting of convex portions 34 and concave portions 35 provided on the second adhesive surface 33 of the holding portion 30 do not fit into each other.

[0023] To achieve this configuration, in the concave-convex structure 36 of this embodiment, as shown in FIG. 3 , the convex portion 34 is provided at the center of the second adhesive surface 33, protruding in a cylindrical or truncated cone shape in the opposite direction from the support portion 32 so that its center is concentric with the center O of the arc-shaped edge 31a. The concave portion 35 is provided on the outer periphery (radially outward) of the convex portion 34 of the second adhesive surface 33, and both sides of the ring formed between the outer periphery of the convex portion 34 and the pair of arc-shaped edges 31a are partially cut out by a pair of straight edges 31b. Therefore, the convex portions 34 and the concave portions 35 of the concave-convex structure 36 of this embodiment have a concentric shape in a plan view and are arranged concentrically. Note that the shape of the concave-convex structure 36 is not limited to a circle or annulus, and can also be an ellipse, an oval, or a polygon. However, a circle or annulus is preferable, and it is even more preferable that they are arranged concentrically around the center O. This allows stress to be transmitted more uniformly from the holding portion 30 to the processed portion 20, thereby more appropriately reducing the risk of the processed portion 20 breaking.

[0024] The uneven structure 36 of the present disclosure is composed of unevenness having a height or depth that allows an adhesive layer 40 of a predetermined thickness to be provided between the first adhesive surface 21 and the second adhesive surface 33. For this reason, the uneven structure 36 of the present disclosure does not include fine unevenness (for example, unevenness having a height or depth of less than 10 μm) that is formed by polishing the first adhesive surface 21 and / or the second adhesive surface 33.

[0025] More specifically, the height of the convex portions 34 or the depth of the concave portions 35 of the concave-convex structure 36 is preferably 80 μm to 400 μm, more preferably 90 μm to 380 μm, even more preferably 100 μm to 350 μm, even more preferably 110 μm to 250 μm, particularly preferably 130 μm to 240 μm, and most preferably 140 μm to 230 μm. In the mill blank assembly 10 of this embodiment shown in FIGS. 1 to 4, the height of the convex portions 34 and the depth of the concave portions 35 are the same. This configuration allows an adhesive layer 40 of a predetermined thickness to be provided between the first adhesive surface 21 and the second adhesive surface 33. Therefore, the adhesive layer 40 can ensure appropriate adhesive strength between the workpiece 20 and the holding portion 30. The shape of the steps of the concave-convex structure 36 may be vertical, rectangular, tapered, or rounded, and is not particularly limited. The height of the convex portion or the depth of the concave portion is measured, for example, by the procedure described in the Examples below.

[0026] The surfaces of the convex portions 34 and the concave portions 35 of the second adhesive surface 33 may have an arithmetic mean roughness Ra of 0.2 μm or less, but may also have fine irregularities as described above to form a so-called rough surface. The first adhesive surface 21 may also have fine irregularities to form a rough surface. By providing such fine irregularities, the compressive shear adhesive strength of each of the first adhesive surface 21, the second adhesive surface 33, and the adhesive layer 40 can be increased. Furthermore, such fine irregularities do not affect the effect of the uneven structure 36 provided on the second adhesive surface 33.

[0027] The support column 32 is provided in a cylindrical or truncated cone shape and protrudes from a base 31c provided on the surface of the base 31 opposite the second adhesive surface 33. As described above, the arc edge 31a, the convex portion 34, and the center O of the concave portion 35 of the base 31 are located on the central axis of the support column 32. In other words, the support column 32 is formed in a concentric shape (concentric circle shape) with the convex portion 34 of the base 31 in a plan view.

[0028] The support portion 32 is constricted so that its approximate center is curved inward, and this constricted portion serves as a chuck portion 32a. The chuck portion 32a is engaged with a fixture provided in a chuck device of the dental processing equipment, thereby fixing the support portion 32 to the chuck device. The support portion 32 also has a second notch 32b at the tip opposite to the side fixed to the base 31. The second notch 32b also functions as a positioning portion or the like for determining the attachment direction of the holding portion 30 to the chuck device.

[0029] 1 and the like, the side shape of the cylindrical base 31c including the first cutout 31d may be a vertical cylindrical shape, a truncated cone shape with a tapered inclination, or a curved surface such as an R-shape. For example, in the case of a vertical cylindrical shape, in a CAD / CAM processing machine in the CEREC system of Dentsply Sirona, the base 31c functions as a touch sensor that confirms the initial position of the bur by bringing the processing bur into contact with the side surface of the cylindrical base 31c immediately before processing.

[0030] As described above, the adhesive layer 40 is disposed between the first adhesive surface 21 and the second adhesive surface 33, which are the adhesive surfaces of the workpiece portion 20 and the holding portion 30, and bonds the workpiece portion 20 and the holding portion 30 together.

[0031] The adhesive layer 40 is formed by curing an adhesive composition (also referred to as an "adhesive") that has been applied (e.g., dropped) between the first adhesive surface 21 and the second adhesive surface 33. For example, the adhesive composition is applied to the center of the second adhesive surface 33 (in this embodiment, the surface of the convex portion 34 shown in FIG. 3 ) or the center of the first adhesive surface 21, and then the first adhesive surface 21 of the workpiece 20 is pressed against the second adhesive surface 33. The adhesive is then allowed to stand at room temperature (e.g., 20°C), whereby the adhesive hardens, forming the adhesive layer 40 and adhering and fixing the workpiece 20 and the holding part 30. While it is desirable to apply the adhesive composition to the center of the second adhesive surface 33, it does not necessarily have to be applied exactly in the center; it is sufficient if it is applied approximately in the center.

[0032] The adhesive composition is not particularly limited, and known adhesive compositions can be used. Suitable adhesives include epoxy adhesives, epoxy-modified silicone adhesives, cyanoacrylate adhesives, (meth)acrylate adhesives, and urethane adhesives. Among these, epoxy adhesives, epoxy-modified silicone adhesives, and cyanoacrylate adhesives are more suitable. Examples of epoxy adhesives include "Bond Quick 30" manufactured by Konishi Co., Ltd., epoxy-modified silicone adhesives include "EP001N" manufactured by Cemedine Co., Ltd., and cyanoacrylate adhesives include "Aron Alpha Extra 4000" manufactured by Toagosei Co., Ltd. Such adhesive compositions have suitable viscosity and quick-drying properties, suppress unexpected diffusion, and allow the appropriate amount of impregnation into the workpiece 20, resulting in an adhesive layer 40 of suitable thickness and size (area).

[0033] The thickness of the adhesive layer 40 is not particularly limited, but is preferably 3 μm to 450 μm, more preferably 5 μm to 360 μm, and most preferably 8 μm to 260 μm. The thickness of the adhesive layer 40 refers to the thickest portion. By adhering the flat first adhesive surface 21 to the second adhesive surface 33 having the concave-convex structure 36, the adhesive layer 40 provided between the first adhesive surface 21 and the surface of the convex portion 34 (hereinafter referred to as the "first adhesive layer 41") will have a different thickness from the adhesive layer 40 provided between the first adhesive surface 21 and the surface of the concave portion 35 (hereinafter referred to as the "second adhesive layer 42"). The thickness of the adhesive layer 40 is measured, for example, by the procedure described in the Examples below.

[0034] Therefore, more specifically, the thickness of the first adhesive layer 41 in the convex portion 34 is preferably 3 μm to 50 μm, more preferably 5 μm to 40 μm, and most preferably 8 μm to 20 μm. Meanwhile, the thickness of the second adhesive layer 42 in the concave portion 35 is preferably 80 μm to 400 μm, more preferably 100 μm to 360 μm, and most preferably 110 μm to 260 μm. In other words, from the viewpoint of making it difficult for the thermal expansion or thermal contraction of the holding portion 30 to be transmitted to the workpiece 20, it is desirable for the first adhesive layer 41 and the second adhesive layer 42 to be thicker, which can reduce the risk of breakage due to temperature changes or vibration, particularly at low temperatures. The thicknesses of the first adhesive layer 41 and the second adhesive layer 42 refer to their thickest portions. Furthermore, if the thickness of the adhesive layer 40 is too thick, cracks or small fractures may occur inside the adhesive layer 40 before the workpiece portion 20 breaks, which is undesirable because it reduces the peel adhesion strength (N1 and N2 described below) and makes it impossible to maintain appropriate adhesion between the workpiece portion 20 and the holding portion 30.

[0035] Furthermore, a larger thickness difference (hereinafter referred to as "step") between the first adhesive layer 41 and the second adhesive layer 42 within the first adhesive surface 21 is desirable, as this reduces the risk of fracture of the workpiece 20 by alleviating stress due to expansion or contraction of the retaining portion 30 and making it less likely to be transmitted to the workpiece 20. Meanwhile, in the first embodiment, a smaller step is desirable for the retaining portion 30 to fix the workpiece 20. A smaller step is also desirable from the perspective of reducing the amount of adhesive used. This step is preferably 70 μm to 400 μm, more preferably 90 μm to 350 μm, and even more preferably 100 μm to 250 μm. The shape of the step may be vertical, rectangular, tapered, or rounded, and is not particularly limited. The thickness of the adhesive layer 40 is measured, for example, using the following procedure.

[0036] By setting the thickness and step of the first adhesive layer 41 and the second adhesive layer 42 within the ranges described above, the adhesive layer 40 can reduce the risk of breakage of the processed portion 20 while maintaining the appropriate adhesive strength required to properly bond and fix the processed portion 20 and the holding portion 30 together.

[0037] Furthermore, the shape and area of ​​the adhesive layer 40 in a plan view are preferably as follows, but are not limited to the following as long as the first adhesive surface 21 and the second adhesive surface 33 are bonded with an appropriate adhesive strength. In Figures 3 and 4, the first adhesive layer 41 and the second adhesive layer 42 are indicated by dashed lines. As shown in these figures, the adhesive layer 40 is preferably substantially circular in plan view and concentric with the convex portion 34. If the adhesive layer 40 is eccentric with respect to the convex portion 34, the area where the workpiece 20 and the holding portion 30 are not bonded via the adhesive layer 40 will be closer to the center, making it difficult for the holding portion 30 to stably support the workpiece over its entire surface, which may result in reduced processing accuracy and / or processing difficulties, which is undesirable.

[0038] The first adhesive layer 41 has approximately the same area as the convex portion 34 of the second adhesive surface 33, and the second adhesive layer 42 can fill part or all of the concave portion 35 of the second adhesive surface 33. In order to mitigate thermal expansion or thermal contraction of the holding portion 30, it is desirable that the outer periphery of the second adhesive layer 42 be located inside the outer periphery of the concave portion 35 and have a smaller area than the concave portion 35, thereby making it difficult for the thermal expansion or thermal contraction of the holding portion 30 to be transmitted to the workpiece, thereby reducing the risk of fracture. In other words, it is desirable that the first adhesive surface 21 and the second adhesive surface 33 are not bonded near the outer periphery of the second adhesive surface 33. On the other hand, from the perspective of increasing the adhesive strength (also referred to as "peel adhesion strength") between the holding portion 30 and the workpiece 20, it is preferable that the second adhesive layer 42 fill the entire concave portion 35 of the second adhesive surface 33, as this increases the adhesive strength.

[0039] With this configuration, the mill blank assembly 10 of this embodiment maintains an appropriate adhesive strength between the workpiece portion 20 and the holding portion 30 via the adhesive layer 40, while suppressing the effects of internal stress due to differences in thermal contraction or thermal expansion between the workpiece portion 20 and the holding portion 30, thereby further reducing the risk of breakage of the workpiece portion 20.

[0040] The amount of adhesive composition to be applied is not particularly limited, but is preferably 0.004 ml to 0.040 ml, and an adhesive layer 40 having the appropriate thickness and area as described above and having the excellent effects as described above can be obtained.

[0041] The relationship between the areas of the first adhesive surface 21, the second adhesive surface 33, and the adhesive layer 40 is preferably as follows: Hereinafter, the area of ​​the first adhesive surface 21 (i.e., the area of ​​the surface of the workpiece 20 on which the first adhesive surface 21 is provided in a plan view) is defined as S1, and the total area of ​​the second adhesive surface 33 (i.e., the area of ​​the base 31 in a plan view, excluding the areas of the concave-convex structure 36 in the height and depth directions) is defined as S2. The contact area between the adhesive layer 40 (first adhesive layer 41) on the convex portions 34 (convex portions 22 in the seventh embodiment described below) of the concave-convex structure 36 and the first adhesive surface 21 of the workpiece 20 is defined as S3. The contact area between the adhesive layer 40 (second adhesive layer 42) and the first adhesive surface 21 in the concave portions 35 (convex portions 23 in the seventh embodiment described below) is defined as S4. The total contact area between the first adhesive surface 21 of the workpiece 20 and the adhesive layer 40 is designated as S5. The units of the areas indicated by S1 to S5 are "mm 2 "

[0042] The total area S1 of the first adhesive surface 21 is 120 mm 2 ~900mm 2 is desirable, 170 mm 2 ~500mm 2 is more preferable, and 220 mm 2 ~400mm 2 is more preferable, and 290 mm 2 ~350mm 2 is especially desirable, 294 mm 2 ~342mm 2 The total area S2 of the second adhesive surface 33 is 110 mm 2 ~800mm 2 is desirable, and 150 mm 2 ~450mm 2 is more preferable, and 180 mm 2 ~300mm 2 is more preferable, and 200 mm 2 ~270mm 2 is especially desirable, 216 mm 2 ~263mm 2By setting the total area S1 of the first adhesive surface 21 within this range, the mill blank assembly 10 maintains an appropriate adhesive strength between the workpiece 20 and the holding portion 30 via the adhesive layer 40, while suppressing the effects of internal stress due to differences in thermal contraction or thermal expansion between the workpiece 20 and the holding portion 30, thereby improving vibration resistance.

[0043] The contact area S3 between the adhesive layer 40 (first adhesive layer 41) on the convex portion 34 and the first adhesive surface 21 of the workpiece 20 is 0 mm 2 ~135mm 2 is desirable, and 0 mm 2 ~100mm 2 is more preferable, and 0 mm 2 ~85mm 2 In this case, when the protrusion 34 is provided at the center of the second adhesive surface 33 as in the first embodiment and the second to fourth and sixth embodiments described later, the contact area S3 is 15 mm 2 ~135mm 2 is desirable, and 20 mm 2 ~100mm 2 is more preferable, and 25 mm 2 ~85mm 2 On the other hand, when the convex portion 34 is not provided in the center of the second adhesive surface 33 but is provided on the outer periphery of the concave portion 35, as in the fifth embodiment described later, the contact area S3 is 0 mm 2 (That is, the adhesive composition is not applied to the convex portion 34.) In addition, the contact area S4 between the adhesive layer 40 (second adhesive layer 42) and the first adhesive surface 21 in the concave portion 35 is 0 mm 2 ~600mm 2 is desirable, and 20 mm 2 ~350mm 2 is more preferable, and 35 mm 2 ~300mm 2 is more preferable, and 50 mm 2 ~250mm 2 is especially desirable, and 80 mm 2 ~200mm 2 is most desirable.

[0044] By setting the contact area S3 and the contact area S4 within the ranges and ratios described above, the mill blank assembly 10 of this embodiment maintains an appropriate adhesive strength between the workpiece portion 20 and the holding portion 30 via the adhesive layer 40, while suppressing the effects of internal stress due to differences in thermal contraction or thermal expansion between the workpiece portion 20 and the holding portion 30, thereby improving vibration resistance.

[0045] The total contact area S5 between the first adhesive surface 21 and the adhesive layer 40 is 10 mm 2 ~680mm 2 is desirable, and 15 mm 2 ~400mm 2 is more preferable, and 18 mm 2 ~300mm 2 is more preferable, and 20 mm 2 ~230mm 2 is especially desirable, 27 mm 2 ~223mm 2 Even by setting the thickness within this range, the mill blank assembly 10 of this embodiment maintains an appropriate adhesive strength between the workpiece 20 and the holding portion 30 via the adhesive layer 40, while suppressing the influence of internal stress due to differences in thermal contraction or thermal expansion between the workpiece 20 and the holding portion 30, thereby improving vibration resistance.

[0046] The ratio of each of the above areas is preferably within the following range. In this specification, the ratio (B / A) refers to the numerical value of B / A x 100 (%). More specifically, the ratio of area B to area A is expressed as B / A x 100 (%). The ratio (S5 / S1) of the total contact area S5 between the first adhesive surface 21 of the workpiece 20 and the adhesive layer 40 to the total area S1 of the first adhesive surface 21 of the workpiece 20 is preferably 8.0% to 75.0%, more preferably 9.0% to 65.0%. The ratio (S5 / S2) of this total contact area S5 to the total area S2 of the second adhesive surface 33 is preferably 10.0% to 90.0%, more preferably 13.0% to 85.0%. By setting the thickness within this range, the mill blank assembly 10 of this embodiment maintains an appropriate adhesive strength between the workpiece portion 20 and the holding portion 30 via the adhesive layer 40, while suppressing the effects of internal stress due to differences in thermal contraction or thermal expansion between the workpiece portion 20 and the holding portion 30, thereby improving vibration resistance.

[0047] In addition, when a central convex portion 34 is present, the ratio S3 / S1 is preferably 4.5% to 40.0%, more preferably 7.0% to 35.0%, and even more preferably 8.5% to 30.0%. When a central convex portion 34 is not present, the ratio S4 / S1 is preferably 0.0% to 65.0%, and even more preferably 0.0% to 57.0%. When a central convex portion 34 is present, the ratio S3 / S2 is preferably 7.5% to 55.0%, more preferably 9.0% to 45.0%, and even more preferably 10.0% to 40.0%, and when a central convex portion 34 is not present, the ratio S4 / S2 is preferably 0.0% to 60.0%, and even more preferably 0.0% to 52.0%. By setting the above ratios within these ranges, the mill blank assembly 10 of this embodiment maintains an appropriate adhesive strength between the workpiece portion 20 and the holding portion 30 via the adhesive layer 40, while suppressing the effects of internal stress due to differences in thermal contraction or thermal expansion between the workpiece portion 20 and the holding portion 30, thereby improving vibration resistance.

[0048] In this case, from the viewpoint of preventing the thermal contraction of the holding portion 30 from being transmitted to the workpiece 20, it is desirable that the ratio S3 / S2 be a smaller value (for example, S3 / S2≦37.0%) and the ratio S4 / S2 be a larger value (for example, S4 / S2≧24.0%). This enables the mill blank assembly 10 of this embodiment to reduce the risk of breakage due to temperature changes or vibrations, particularly at low temperatures.

[0049] Furthermore, from the viewpoint of the adhesive area, it is desirable that the ratios S3 / S1 and S4 / S1 be larger (for example, S3 / S1≧7.9%, S4 / S1≧16.0%). In particular, since the adhesive composition is impregnated into the workpiece 20 and a resin-impregnated layer is formed, it is desirable that the ratio S3 / S1 be larger. This resin-impregnated layer serves as an anchor, maintaining an appropriate adhesive strength between the workpiece 20 and the adhesive layer 40, and can suppress peeling of the surface of the workpiece 20 even if the workpiece 20 peels off from the holding part 30.

[0050] Furthermore, since the second adhesive layer 42 fills the gap between the second adhesive surface 33 and the recess 35, and alleviates the stress caused by the expansion or contraction of the holding portion 30, making it less likely to be transmitted to the processed portion, thereby reducing the risk of fracture of the processed portion 20, it is desirable for S4 / S1 to be a larger value.

[0051] Furthermore, in the mill blank assembly 10 of this embodiment, the peel adhesion strength N1 between the first adhesive surface 21 of the workpiece 20 and the second adhesive surface 33 of the holder 30 after bonding the workpiece 20 and the holder 30 and leaving them at 20°C for 24 hours is preferably 100 N or more, more preferably 200 N or more, and even more preferably 250 N or more. The peel adhesion strength is measured, for example, by the procedure described in the Examples below.

[0052] Furthermore, the mill blank assembly 10 of this embodiment has a peel adhesion strength N2 between the first adhesive surface 21 of the workpiece 20 and the second adhesive surface 33 of the retaining portion 30 after being stored at −30° C. for 24 hours and then left to stand at room temperature (e.g., 20° C.) for 24 hours, of preferably 100 N or more, more preferably 200 N or more, even more preferably 250 N or more, and most preferably 300 N or more. This further reduces the risk of breakage of the workpiece 20 when the workpiece 20 and retaining portion 30, which are bonded together by the adhesive layer 40, are peeled away from each other.

[0053] Furthermore, the ratio N2 / N1 of the peel adhesion strength N2 to the peel adhesion strength N1, i.e., N2 / N1 × 100 (%), is preferably 70% or greater, more preferably 80% or greater, even more preferably 90% or greater, and most preferably 100% or greater. By setting the ratio N2 / N1 within this range, the mill blank assembly 10 can more appropriately reduce the risk of breakage of the workpiece 20, particularly in cold environments. Peel adhesion strength is measured, for example, by the following procedure.

[0054] As described above, the mill blank assembly 10 of the first embodiment can further reduce the risk of breakage of the workpiece 20 due to temperature changes or vibrations while maintaining the necessary adhesive strength to properly bond the workpiece 20 and the holding part 30. In particular, the mill blank assembly 10 of the first embodiment can reduce the risk of breakage of the workpiece 20 due to extremely cold environments or vibrations during transportation. Furthermore, the mill blank assembly 10 of the first embodiment reduces vibrations during product transportation and allows for a reduction in the amount of cushioning material used in product packaging, thereby reducing the environmental impact and minimizing product boxes.

[0055] Second Embodiment A mill blank assembly 10 according to a second embodiment of the present disclosure will be described below with reference to Figures 5 to 7. The mill blank assembly 10 according to the second embodiment has the same basic configuration as the mill blank assembly 10 according to the first embodiment, except for the configuration of the concave-convex structure 36. Therefore, in the description of the second embodiment and the following descriptions of the third to seventh embodiments, the same components as those in the first embodiment are given the same reference numerals, detailed description is omitted, and the components different from the first embodiment will be mainly described.

[0056] The mill blank assembly 10 according to the second embodiment includes a workpiece 20 (see FIG. 1, etc.), a holding portion 30A (see FIGS. 5 to 7), and an adhesive layer 40 (see FIG. 1, etc.). The workpiece 20 and adhesive layer 40 have the same configurations as those of the first embodiment shown in FIG. 1, etc.

[0057] 5 to 7, the holding portion 30A of the second embodiment includes a flat base 31 having a pair of arcuate edges 31a and a pair of linear edges 31b, and a cylindrical support portion 32. The base 31 of the second embodiment has a shape that is line-symmetric and point-symmetric, similar to the base 31 of the first embodiment.

[0058] In the second embodiment, the uneven structure 36 provided on the second adhesive surface 33 includes a circular convex portion (hereinafter referred to as a "first convex portion 34a") provided in the center of the second adhesive surface 33, an annular concave portion (hereinafter simply referred to as a "convex portion 35") provided on the outer periphery of the first convex portion 34a, and an annular convex portion (hereinafter referred to as a "second convex portion 34b") provided on the outer periphery of the concave portion 35. The concave portion 35 and the second convex portion 34b are provided concentrically with the first convex portion 34a.

[0059] When bonding the second adhesive surface 33 having such a configuration to the first adhesive surface 21, it is desirable to form an adhesive layer 40 on the upper surface of the first convex portion 34a and in the recess 35, and to prevent the adhesive layer 40 from being formed on the upper surface of the second convex portion 34b. With this configuration, it is possible to appropriately suppress the internal stress caused by thermal contraction or thermal expansion of the holding portion 30 from being transmitted to the workpiece 20.

[0060] The mill blank assembly 10 of the second embodiment, configured as described above, also achieves the same effects as the mill blank assembly 10 of the first embodiment. Furthermore, the mill blank assembly of the second embodiment supports the central portion of the first adhesive surface 21 of the workpiece 20 with the first protrusion 34a, and supports the vicinity of the periphery of the first adhesive surface 21 with the second protrusion 34b provided on the periphery, thereby increasing the support area and improving support stability. Furthermore, an adhesive layer 40 (second adhesive layer 42, see FIG. 3 ) of appropriate thickness is formed between the bottom surface of the recess 35 and the first adhesive surface 21. This second adhesive layer 42 is preferably thicker than the first adhesive layer 41, so that stress due to the difference in linear expansion between the holding portion 30 and the workpiece 20 can be alleviated by the second adhesive layer 42. As a result, the mill blank assembly 10 of the second embodiment can more appropriately reduce the risk of breakage of the workpiece 20 due to temperature changes or vibrations, particularly in cold environments, and further, since the support area of ​​the holding portion 30 provided by the second convex portion 34b is large, the support stability of the workpiece 20 by the holding portion 30 is further improved.

[0061] Third Embodiment A mill blank assembly 10 according to a third embodiment of the present disclosure will be described below with reference to FIGS. 8 to 10. The mill blank assembly 10 according to the third embodiment has the same basic configuration as the mill blank assembly 10 according to the second embodiment shown in FIG. 5 and other figures, except that the recess 35 provided on the second adhesive surface 33 of the retaining portion 30B and the second protrusion 34b have different areas. More specifically, the second protrusion 34b according to the third embodiment has a narrower radial width of the annular portion than the second protrusion 34b according to the second embodiment, and both sides of the annular portion are interrupted, thereby resulting in a smaller surface area. The recess 35 according to the third embodiment has a wider annular portion than the recess 35 according to the second embodiment, thereby resulting in a larger surface area.

[0062] The mill blank assembly 10 of the third embodiment, configured as described above, also achieves the same effects as the mill blank assemblies 10 of the first and second embodiments. Furthermore, the mill blank assembly 10 of the third embodiment has a larger recess 35 and the inner edge of the second protrusion 34b is positioned further outward than in the second embodiment, thereby more appropriately reducing the formation of an adhesive layer 40 on the upper surface of the second protrusion 34b during bonding. Additionally, the larger recess 35 allows for a wider second adhesive layer 42, thereby enhancing the adhesive strength between the holding portion 30B and the workpiece 20. As a result, the mill blank assembly 10 of the third embodiment can more appropriately reduce the risk of breakage of the workpiece 20 due to temperature changes or vibrations, particularly in cold environments. In the third embodiment, the second embodiment, and the fourth and eighth embodiments described below, the first and second protrusions 34a and 34b are formed to the same height and their respective upper surfaces are arranged on the same plane, so-called flush, but this configuration is not limited thereto. The first and second protrusions 34a and 34b can also be formed to different heights. For example, by making the height of the first protrusions 34a higher than the height of the second protrusions 34b, the adhesive area of ​​the adhesive layer 40 can be increased, and the peel adhesion strength of the adhesive layer 40 can be further improved.

[0063] 11 to 14, the mill blank assembly 10 according to the fourth embodiment of the present disclosure will be described below. The mill blank assembly 10 according to the fourth embodiment has the same basic configuration as the mill blank assembly 10 according to the third embodiment shown in FIG. 8, etc., except that the base 31 of the holding portion 30C is cut out on both sides by two parallel straight lines, with one side being cut out linearly with a larger area than the other side, such that the straight edge 31b on one side is longer than the straight edge 31b on the other side, and the distance from the center O of the pair of straight edges 31b and their lengths are different.

[0064] The base 31 of the holding part 30C of the fourth embodiment is configured to have a first convex part 34a provided on the second adhesive surface 33, a concave part 35 provided on the outer periphery of the first convex part 34a, and a second convex part 34b provided on the outer periphery of the concave part 35. The first convex part 34a, the concave part 35, the second convex part 34b, and the pair of arc edges 31a are formed concentrically around the center O on the axis of the support part 32.

[0065] In the fourth embodiment, since the pair of straight edges 31b of the base 31 have the above-described configuration, as can be seen from Fig. 12 etc., when the line D-D that passes through the center O and is parallel to the straight edges 31b is taken as the axis of symmetry, the base 31 and the second adhesive surface 33 have asymmetric shapes. On the other hand, as can be seen from Fig. 12 etc., when the line E-E that passes through the center O and is perpendicular to the straight edges 31b is taken as the axis of symmetry, the base 31 and the second adhesive surface 33 have line-symmetric shapes.

[0066] Therefore, in the direction toward the pair of straight edges 31b (the width direction parallel to line E-E), the first protrusion 34a is provided at a position eccentric (near the center) from the center (center of gravity) of the base 31. On the other hand, in the direction toward the pair of arcuate edges 31a (the longitudinal direction parallel to line D-D), the first protrusion 34a is provided at the center of the base 31.

[0067] The mill blank assembly 10 of the fourth embodiment configured as described above also provides the same effects as the mill blank assemblies 10 of the first and third embodiments. Furthermore, the mill blank assembly 10 of the fourth embodiment has an asymmetrical base 31 with one straight edge 31b cut out significantly. Therefore, when the mill blank assembly 10 is attached to the attachment device of the processing device, the straight edge 31b of the base 31 cut out significantly does not protrude from the chuck device, allowing for smooth processing operations.

[0068] Fifth Embodiment A mill blank assembly 10 according to a fifth embodiment of the present disclosure will be described below with reference to Figures 15 to 17. The mill blank assembly 10 according to the fifth embodiment has the same basic configuration as the mill blank assembly 10 according to the second embodiment shown in Figure 5 and the like, except that the second adhesive surface 33 of the retaining portion 30D does not have a protrusion like the first protrusion 34a provided in the second embodiment shown in Figure 5 and the like.

[0069] The base 31 of the holding portion 30D of the fifth embodiment has, on the second adhesive surface 33, a circular recess 35 centered at the center O, and a protrusion 34 arranged concentrically with the recess 35 on the outer periphery of this recess 35, with no protrusion in the center.

[0070] In the mill blank assembly 10 of the fifth embodiment, when the second adhesive surface 33 and the first adhesive surface 21 are bonded together, it is desirable that the adhesive layer 40 be formed over the entire recess 35 or in an area inside the periphery of the recess 35, and that the adhesive layer 40 be not formed on the top surface of the protrusion 34. This configuration makes it possible to appropriately suppress the internal stress caused by thermal contraction or thermal expansion of the holding portion 30D from being transmitted to the workpiece 20.

[0071] The mill blank assembly 10 of the fifth embodiment configured as described above also provides the same effects as the mill blank assemblies 10 of the first and second embodiments. Furthermore, in the mill blank assembly 10 of the fifth embodiment, the recess 35 has a large area, so the thickness of the adhesive layer 40 can be made thicker, more uniform, and have a more appropriate area, thereby improving adhesive strength and vibration damping properties and reducing the risk of breakage.

[0072] Sixth Embodiment A mill blank assembly 10 according to a sixth embodiment of the present disclosure will be described as follows with reference to Figures 18 to 20. The mill blank assembly 10 according to the sixth embodiment has the same basic configuration as the mill blank assembly 10 according to the first embodiment shown in Figure 1, etc., except that a concave-convex structure 24 is provided on the first adhesive surface 21 of the workpiece portion 20E and the second adhesive surface 33 of the retaining portion 30E is flat (more preferably, a flat surface with an arithmetic mean roughness Ra of 0.2 µm or less).

[0073] As shown in FIGS. 19 and 20 , the first adhesive surface 21 of the workpiece 20E of the sixth embodiment includes a circular first protrusion 22a (22) located at the center of the first adhesive surface 21, a ring-shaped recess 23 located on the outer periphery of the first protrusion 22a, and a second protrusion 22b located on the outer periphery of the recess 23. The first protrusion 22a and the recess 23 are arranged concentrically. The first protrusion 22a, the recess 23, and the second protrusion 22b of the first adhesive surface 21 are configured not to fit together, and the entire area of ​​the first adhesive surface 21 and the second adhesive surface 33 of the holding portion 30E are configured not to fit together. The steps between the first protrusion 22a and the second protrusion 22b and the recess 23 may be vertical, rectangular, tapered, or rounded, and are not particularly limited.

[0074] When bonding the first adhesive surface 21 and the second adhesive surface 33 having such a configuration, for example, an adhesive composition may be applied to the center of the flat second adhesive surface 33, and the first adhesive surface 21 may be pressed against it. This results in an adhesive layer 40 being formed on at least the surfaces of the first convex portions 22a, and more preferably on the surfaces of the first convex portions 22a and the concave portions 23. At this time, it is desirable to avoid forming an adhesive layer 40 on the surfaces of the second convex portions 22b. Furthermore, for example, if the adhesive composition has high viscosity, the adhesive composition may be applied (e.g., dripped) to the center (near the center O) of the first adhesive surface 21 of the workpiece 20E, and the flat second adhesive surface 33 may be pressed against it from above. Note that the bonding procedure here is not particularly limited as long as the adhesive composition can be impregnated into the workpiece 20E to increase adhesive strength.

[0075] Even with this configuration, the first adhesive surface 21 and the second adhesive surface 33 are bonded with an appropriate adhesive strength by the adhesive layer 40, while the internal stress due to thermal contraction or thermal expansion of the holding portion 30E can be appropriately suppressed from being transmitted to the processed portion 20E.

[0076] The mill blank assembly 10 of the sixth embodiment, configured as described above, also achieves the same effects as the mill blank assembly 10 of the first embodiment and the second embodiment. Furthermore, the mill blank assembly of the sixth embodiment only requires the uneven structure 24 to be provided on the first adhesive surface 21 of the workpiece 20E, allowing the use of an existing holding part whose second adhesive surface 33 is flat, thereby reducing product costs and improving versatility. The shape of the second adhesive surface 33 of the holding part 30E to be bonded may be, for example, point-symmetric or line-symmetric in an oval shape, and is not particularly limited. Furthermore, the mill blank assembly 10 of the sixth embodiment has a large recess 23, which more appropriately reduces the formation of an adhesive layer 40 on the surface of the second protrusion 22b during bonding, thereby enhancing the adhesive strength between the holding part 30E and the workpiece 20E. Therefore, the mill blank assembly 10 of the sixth embodiment more appropriately reduces the risk of breakage of the workpiece 20E due to temperature changes or vibrations, particularly in cold environments.

[0077] Seventh Embodiment A mill blank assembly 10 according to a seventh embodiment of the present disclosure will be described as follows with reference to Figures 18, 21 and 22. As with the sixth embodiment, the mill blank assembly 10 according to the seventh embodiment has a concave-convex structure 24 provided on the first adhesive surface 21 of the workpiece 20F, and the second adhesive surface 33 of the holder 30E is flat (more preferably, a flat surface with an arithmetic mean roughness Ra of 0.2 µm or less).

[0078] As shown in FIGS. 21 and 22 , the first adhesive surface 21 of the seventh embodiment includes a circular recess 23 located in the center of the first adhesive surface 21 and a protrusion 22 located on the outer periphery of the recess 23. The outer peripheral edge of the recess 23 and the inner peripheral edge of the protrusion 22 are aligned, so they are considered to be concentrically arranged. The recess 23 has a configuration similar to the recess 35 of the fifth embodiment shown in FIG. 15 . The protrusion 22 and the recess 23 of the first adhesive surface 21 are configured not to fit together, and the first adhesive surface 21 and the entire second adhesive surface 33 of the holding portion 30E are configured not to fit together. The step between the protrusion 22 and the recess 23 may be vertical, rectangular, tapered, or rounded, and is not particularly limited.

[0079] When bonding the first adhesive surface 21 and the second adhesive surface 33 configured as described above, an adhesive composition is applied to the center of the flat second adhesive surface 33 or the center of the first adhesive surface 21, and the first adhesive surface 21 is pressed against the second adhesive surface 33. This forms an adhesive layer 40 on the surface of the recessed portion 23. At this time, it is desirable to avoid forming the adhesive layer 40 on the surface of the protruding portion 22. This configuration also makes it possible to appropriately suppress the internal stress caused by thermal contraction or thermal expansion of the holding portion 30E from being transmitted to the workpiece portion 20F.

[0080] The mill blank assembly 10 of the seventh embodiment configured as described above also achieves the same effects as the mill blank assembly 10 of the first embodiment and the sixth embodiment. Furthermore, the mill blank assembly 10 of the seventh embodiment, like the second embodiment, allows the adhesive layer 40 to have a more uniform thickness and a more appropriate area. Furthermore, like the fifth embodiment, the mill blank assembly 10 of the seventh embodiment has a large area of ​​the recess 23, allowing the adhesive layer 40 to have a thicker, more uniform, and more appropriate area, thereby improving adhesive strength and vibration damping and reducing the risk of breakage.

[0081] Eighth Embodiment A mill blank assembly 10 according to an eighth embodiment of the present disclosure will be described below with reference to FIG. 22A . The mill blank assembly 10 according to the eighth embodiment has the same basic configuration as the mill blank assembly 10 according to the third embodiment shown in FIG. 8 , etc., except that the recessed portion 35 and the second protruding portion 34b provided on the second adhesive surface 33 of the retaining portion 30G have different areas. More specifically, the circumferential length of the pair of second protruding portions 34b in the third embodiment is substantially the same as the pair of arcuate edges 31a of the base 31, whereas the circumferential length of the pair of second protruding portions 34b in the eighth embodiment is shorter than the pair of arcuate edges 31a. With this configuration, the surface area of ​​the second protruding portions 34b in the eighth embodiment is narrower, and the surface area of ​​the recessed portion 35 is wider.

[0082] The circumferential length of the pair of second protrusions 34b is not particularly limited, but is preferably approximately 80% of the length of the pair of arcuate edges 31a, more preferably approximately 50%, and most preferably approximately 30%. As shown in FIG. 22A , the pair of second protrusions 34b in the eighth embodiment are arranged line-symmetrically and point-symmetrically at approximately the center of the pair of arcuate edges 31a, but this configuration is not limited thereto. The pair of second protrusions 34b may be arranged line-symmetrically, point-symmetrically, or randomly on one or the other side of the pair of arcuate edges 31a in the circumferential direction. Furthermore, one second protrusion 34b may be arranged on each arcuate edge 31a, or multiple second protrusions 34b may be arranged at predetermined intervals.

[0083] The mill blank assembly 10 of the eighth embodiment configured as described above also achieves the same effects as the mill blank assemblies 10 of the first and second embodiments. Furthermore, because the area of ​​the recess 35 in the mill blank assembly 10 of the eighth embodiment is large, a larger amount of adhesive is applied to the second adhesive surface 33, thereby further improving the peel adhesion strength of the adhesive layer 40. As a result, the mill blank assembly 10 of the eighth embodiment can more appropriately reduce the risk of breakage of the workpiece 20 due to temperature changes or vibrations, particularly in cold environments.

[0084] Ninth Embodiment A mill blank assembly 10 according to a ninth embodiment of the present disclosure will be described below with reference to FIG. 22B . The mill blank assembly 10 according to the ninth embodiment has the same basic configuration as the mill blank assembly 10 according to the first embodiment shown in FIG. 1 , etc., except for the shape of the concave-convex structure 36 provided on the second adhesive surface 33 of the retaining portion 30H. More specifically, the convex portions 34 in the ninth embodiment are composed of multiple linear protrusions extending radially from the center of the base 31 on the second adhesive surface 33. The portions of the second adhesive surface 33 other than these radial convex portions 34 form concave portions 35. In the example shown in FIG. 22B , eight radial convex portions 34 are provided from the center, but the number is not limited to eight. The radial (radial) length of the convex portions 34 is not particularly limited and may be a length that is inside the outer periphery of the base 31 as shown in FIG. 22B , or may reach the outer periphery. Furthermore, all of the convex portions 34 may have the same length, or may have different lengths. The height of the protrusion 34 can be the same as in the first embodiment, and the width can be set to 1 mm to 1.5 mm, but is not limited thereto.

[0085] The mill blank assembly 10 of the ninth embodiment configured as described above also provides the same effects as the mill blank assemblies 10 of the first and second embodiments. Furthermore, the mill blank assembly 10 of the ninth embodiment is easy to manufacture because the convex portion 34 is linear and point-symmetric, and the support stability of the workpiece 20 by the holding portion 30 is excellent. For these reasons, the mill blank assembly 10 of the ninth embodiment can more appropriately reduce the risk of breakage of the workpiece 20 due to temperature changes or vibrations, particularly in cold environments.

[0086] Tenth Embodiment A mill blank assembly 10 according to a tenth embodiment of the present disclosure will be described below with reference to FIG. 22C . The mill blank assembly 10 according to the tenth embodiment has the same basic configuration as the mill blank assembly 10 according to the ninth embodiment shown in FIG. 22B , except for the shape of the convex portions 34 of the uneven structure 36 provided on the second adhesive surface 33 of the retaining portion 30I. More specifically, while the convex portions 34 in the ninth embodiment are composed of eight radial ridges, the convex portions 34 in the tenth embodiment are composed of four radial ridges and have a cross shape in plan view. The width of the convex portions 34 in the tenth embodiment is wider than that in the ninth embodiment.

[0087] The mill blank assembly 10 of the tenth embodiment configured as described above also provides the same effects as the mill blank assemblies 10 of the first and second embodiments. Furthermore, like the ninth embodiment, the mill blank assembly 10 of the tenth embodiment has a linear and point-symmetric convex portion 34, which makes it easy to manufacture and provides excellent support stability for the workpiece 20 by the holding portion 30. As a result, the mill blank assembly 10 of the tenth embodiment can more appropriately reduce the risk of breakage of the workpiece 20 due to temperature changes or vibrations, particularly in cold environments.

[0088] The various physical properties in this specification were measured by the following methods and conditions.

[0089] [Measurement of Vickers Hardness] The Vickers hardness of the workpiece 20 was measured in accordance with JIS Z 2244:2009 and ISO 6872:2015. Using a micro / macro Vickers hardness tester (product name "Falcon500", manufactured by Innovatest Japan Co., Ltd.), a load of 5 kgf was held for 30 seconds, and the Hv value was calculated (average value of n = 10). "HV 5 / 30" means that the sample was held for 30 seconds at a load of 5 kgf as the test force.

[0090] [Measurement of the Height of the Convex Portion or the Depth of the Concave Portion] The height of the convex portion or the depth of the concave portion of each Example and Comparative Example was measured using the following procedure. The holder of each Example or Comparative Example was fixed to a molded urethane fixture so that the adhesive surface was horizontal, and then placed on the sample stage of a color 3D laser microscope (VK-9700, manufactured by Keyence Corporation). Facing the color 3D laser microscope, the left-right direction is the X-axis, the front-back direction is the Y-axis, and the up-down direction is the Z-axis. The position of the holder 3 was adjusted so that the step portion of each Example or Comparative Example was horizontally positioned at the center of the image displayed in the measurement software VK Viewer (software version: 2.5.0.2, manufactured by Keyence Corporation), and the focus was adjusted using the dial on the microscope body. Next, the focus was shifted upward along the Z-axis using the lens position adjustment button on VK Viewer, and the point where the image became completely blurred was determined as the upper limit of the measurement range. Similarly, the focus was shifted downward along the Z-axis, and the point where the image became completely blurred was determined as the lower limit of the measurement range. The Z-axis measurement range was adjusted to approximately twice the height of the convex portion or the depth of the concave portion. Furthermore, the laser brightness was automatically adjusted on the VK Viewer, and a 30% light intensity filter was selected. Measurement was then initiated with a Z-axis measurement pitch of 1 μm, measurement mode set to surface profile, measurement area set to surface, and measurement quality set to high precision. The holding part of each example or comparative example was left at room temperature of 25±2°C for at least 30 minutes prior to measurement to achieve a temperature of 24±2°C. The temperature of the holding part of each example or comparative example was measured using a radiation thermometer (TN418JCR, AS ONE Corporation) from a position 15 cm above the adhesive surface in a vertical direction. The illuminance in the measurement chamber was 500±200 lx, the objective lens was 20x (20x / 0.46 WD3.1, Nikon Corporation), and the VK Viewer zoom function was set to 1.0x. The obtained measurement results were analyzed using the analysis software VK Analyzer (software version: 2.5.0.1, manufactured by Keyence Corporation) to remove noise (detection area: normal) and correct the surface tilt on the top surface of the convex portion so that the measurement results were horizontal. Furthermore, a vertical line was selected in the profile and aligned with the center of the measurement results to obtain a height difference graph. The difference between adjacent upper flat portions or upper ends and lower flat portions or lower ends of this height difference graph was obtained as the height of the convex portion or the depth of the concave portion.Measurements were similarly taken at any five locations including the stepped portion of the holding portion of each Example or Comparative Example, and the average of the measurements was taken as the height of the convex portion or the depth of the concave portion.

[0091] [Measurement of adhesive layer thickness] The produced mill blank assembly was cut, and the adhesive layer thickness of the cured adhesive composition on the cut surface was measured. The thickness of the cured adhesive composition, i.e., the thickness of the adhesive layer 40, was measured by observation with an optical microscope (DIGITAL MICROSCOPE KH-7700: Hirox Co., Ltd.) (n=1).

[0092] [Measurement of Peel Adhesion Strength (Compression Shear Adhesion Test)] The holder was fixed to a fixture, and a load was applied to the processed portion at a point 18 mm from the first adhesive surface using a support roller. The load applied when the processed portion peeled from the holder was measured using a bench-top precision universal testing machine (Autograph AGS-5kNX, manufactured by Shimadzu Corporation). The support roller was lowered at a speed of 1.0 mm / sec. Peel adhesion strength was measured after 24 hours of standing at 20°C after adhesion, or after 24 hours of standing at 20°C, 24 hours of standing at -30°C, and 24 hours of standing at room temperature (e.g., 20°C) (n=5).

[0093] Specific Examples 1 to 40 and Comparative Examples 1 to 3 of the present disclosure are described below with reference to Tables 1 to 7. Tables 1 to 7 show the fabrication conditions, such as the material, type, dimensions, area, and area ratio, of the workpiece portions 20, 20E, 20F, and 2, the retaining portions 30, 30A to 30I, and the adhesive layer 40 of the mill blank assembly 10 of each Example and the mill blank assembly 1 of each Comparative Example, as well as the peel adhesion strength. Based on the fabrication conditions listed in these tables, the inventors fabricated the mill blank assembly 10 of each Example and the mill blank assemblies 10, 1, and 1A of each Comparative Example, and measured the peel adhesion strength using the measurement procedure described above. The peel adhesion strength is shown in both N (Newtons) and Mpa (megapascals).

[0094]

[0095]

[0096] Examples 1 to 5 are specific examples of the mill blank assembly 10 of the first embodiment shown in FIGS. 1 to 4, and as shown in Table 1, the diameter and height of the protrusion 34, the amount of adhesive composition applied, and the thickness and area of ​​the adhesive layer are changed.

[0097] Example 6 is a specific example of the mill blank assembly 10 of the second embodiment shown in Figures 5 to 7. Examples 7 and 8 are specific examples of the mill blank assembly 10 of the third embodiment shown in Figures 8 to 10, in which the total area S2 of the second adhesive surface 33 is changed as shown in Tables 1 and 2.

[0098] Example 9 is a specific example of the mill blank assembly 10 of the fourth embodiment shown in Figures 11 to 14. Examples 10 to 12 are specific examples of the mill blank assembly 10 of the third embodiment shown in Figures 8 to 10, in which the amount of adhesive composition applied and the contact area S4 between the adhesive layer 40 and the first adhesive surface 21 were changed as shown in Table 2. Examples 13 and 14 are specific examples of the mill blank assembly 10 of the fifth embodiment of the present disclosure shown in Figures 15 to 17, in which the amount of adhesive composition applied and the contact area S4 between the adhesive layer 40 and the first adhesive surface 21 were changed as shown in Table 2.

[0099]

[0100] Examples 15 to 17 are specific examples of the mill blank assembly 10 of the third embodiment shown in Figures 8 to 10, in which the material of the retaining portion 30B, the type of adhesive composition, etc. were changed as shown in Table 3. Example 18 is a specific example of the sixth embodiment shown in Figures 18 to 20. Example 19 is a specific example of the mill blank assembly 10 of the seventh embodiment shown in Figures 18, 21, and 22.

[0101]

[0102] Examples 20 and 21 are specific examples of the mill blank assembly 10 of the ninth embodiment shown in Figure 22B, in which the thickness of the adhesive layer 40 was changed by changing the height of the radial convex portions 34 of the retaining portion 30H. Examples 22 and 23 are specific examples of the mill blank assembly 10 of the tenth embodiment shown in Figure 22C. As shown in Table 4, these examples are examples in which the thickness of the adhesive layer 40 was changed by changing the height of the cross-shaped convex portions 34 of the retaining portion 30I.

[0103] Examples 24 to 26 are specific examples of mill blank assemblies 10 according to modifications of the third embodiment shown in FIGS. 8 to 10. As shown in Table 4, Examples 24 to 26 are examples in which fine irregularities are formed on the entire surface of the second adhesive surface 33 of the retaining portion 30B, including the first convex portion 24a, the second convex portion 34b, and the concave portion 35, to achieve an arithmetic mean roughness Ra of 0.81 μm, and the shape of these fine irregularities is further varied. In Example 24, the second adhesive surface 33 is formed with randomly shaped fine irregularities. The term "random shape" refers not to irregularities or grooves expressed as specific figures with a fixed length, such as straight lines, spirals, or circles, but to irregularities or grooves that are randomly formed, for example, by barrel polishing (see Japanese Patent Publication No. 7315316). In Example 25, the second adhesive surface 33 is formed with spiral-shaped fine irregular grooves. In Example 26, a plurality of concentric fine uneven grooves are formed on the second adhesive surface 33. The spiral or concentric fine uneven grooves in Examples 24 and 26 can be easily formed by, for example, lathe processing (see Japanese Patent No. 7315316).

[0104]

[0105]

[0106] Examples 27 to 36 are specific examples of the mill blank assembly 10 of the first embodiment shown in FIGS. 1 to 4, and as shown in Tables 5 and 6, the height of the convex portion 34 of the holding portion 30 is changed to change the thickness of the adhesive layer 40.

[0107] Example 37 is a specific example of the mill blank assembly 10 of the third embodiment shown in FIGS. 8 to 10 , in which the radial width of the second protrusion 34b was reduced as shown in Table 6. Specifically, the diameter of the inner arc (concentric circle) of the second protrusion 34b was 17.1 mm. Examples 38 and 39 are specific examples of the mill blank assembly 10 of the ninth embodiment shown in FIG. 22A , in which the radial width and circumferential length of the second protrusion 34b were changed as shown in Table 6. Specifically, in Example 38, the diameter of the inner arc (concentric circle) of the second protrusion 34b was 15 mm, and in Example 39, the diameter was 17.1 mm. The circumferential length of the second protrusion 34b in Examples 38 and 39 was 3.3% (33%) of the arc edge 31a. Example 40 is a specific example of the mill blank assembly 10 of the third embodiment shown in FIGS. 8 to 10, and is an example in which the radial width of the second convex portion 34b is made thinner and the first convex portion 34a is made higher than the second convex portion 34b, as shown in Table 6.

[0108]

[0109] 23 includes a cylindrical workpiece 2, a holder 3 having a disk-shaped base 3a and cylindrical support posts 3b, and an adhesive layer (not shown) disposed between a first adhesive surface 2a of the workpiece 2 and a second adhesive surface 3c of the holder 3. The first adhesive surface 2a has a circular protrusion 2b in its center, and the second adhesive surface 3c has a circular recess 3d in its center. In Comparative Example 1, when the first adhesive surface 2a and the second adhesive surface 3c are bonded together, the protrusion 2b and the recess 3d fit together.

[0110] 24 includes a cylindrical workpiece 2, a holder 3 having a disk-shaped base 3a and cylindrical support posts 3b, and an adhesive layer (not shown) disposed between a first adhesive surface 2a of the workpiece 2 and a second adhesive surface 3c of the holder 3. The first adhesive surface 2a has a circular recess 2c in its center, and the second adhesive surface 3c has a circular protrusion 3e in its center. The mill blank assembly 1A of Comparative Example 2 is also configured such that when the first adhesive surface 2a and the second adhesive surface 3c are bonded together, the recess 2c and the protrusion 3e fit together.

[0111] Comparative Example 3 is a mill blank assembly in which the adhesive surface of the base and the adhesive surface of the workpiece are formed flat without irregularities, and the arithmetic mean roughness of each adhesive surface is 0.2 μmm.

[0112] From the results in Tables 1 to 7, the mill blank assemblies 10 of Examples 1 to 19 had a peel adhesion strength N1 of 100 N or more between the first adhesive surface 21 of the workpiece 20, etc. and the second adhesive surface 33 of the retaining portion 30, etc. after bonding the workpiece 20, etc. and the retaining portion 30, etc. and leaving them at 20°C for 24 hours. Furthermore, after storing them at -30°C for 24 hours and then leaving them at room temperature (e.g., 20°C) for 24 hours, the peel adhesion strength N2 between the first adhesive surface 21 of the workpiece 20, etc. and the second adhesive surface 33 of the retaining portion 30 was 100 N or more, and the ratio N2 / N1 was 80% or more.

[0113] In contrast, when an attempt was made to measure the peel adhesion strength N2 of the mill blank assembly 1 of Comparative Example 1 and the mill blank assembly of Comparative Example 3, the assembly broke during the measurement and could not be measured. Furthermore, the mill blank assembly 1A of Comparative Example 2 had a peel adhesion strength N1 of 355 N, but the peel adhesion strength N2 was 38 N, a significant decrease in peel adhesion strength, and the ratio N2 / N1 was also low at 11%.

[0114] From the above results, it was found that the mill blank assemblies 10 of Examples 1 to 40 can further reduce the risk of breakage of the workpiece 20, etc. due to temperature changes or vibrations while maintaining the necessary adhesive strength to enable appropriate bonding between the workpiece 20, etc. and the holding portion 30, etc. In particular, it was found that the mill blank assemblies 10 of Examples 1 to 40 can reduce the risk of breakage of the workpiece 20 due to extremely cold environments or vibrations during transportation.

[0115] The first to seventh embodiments and examples 1 to 40 of the present disclosure have been described in detail above with reference to the drawings. However, the above-described embodiments and examples are merely examples of the present disclosure. The present disclosure is not limited to the configurations of the above-described embodiments and examples. It goes without saying that design changes and the like that do not deviate from the gist of the present disclosure are also included in the present disclosure.

[0116] In addition, with respect to the above-described embodiments and examples, the following is further disclosed. (1) A mill blank assembly comprising: a workpiece; a holding portion for holding the workpiece; and an adhesive layer disposed between the adhesive surfaces of the workpiece and the holding portion and adhering the workpiece and the holding portion, wherein at least one of the adhesive surfaces of the workpiece and the holding portion has an uneven structure consisting of convex and concave portions, and the convex and concave portions do not fit together. (2) The mill blank assembly according to (1), wherein the adhesive surface has an arithmetic mean roughness Ra of 0.2 μm or less as defined in JIS B0601:2013. (3) The mill blank assembly according to (1) or (2), wherein the holding portion comprises a base having the adhesive surface provided on one side thereof and a support portion provided on the base opposite the adhesive surface, and wherein at least a portion of the outer periphery of the base is formed in an arc shape centered on the support portion. (4) The mill blank assembly according to any one of (1) to (3), wherein the holding portion comprises a base having the adhesive surface provided on one side thereof and a support portion provided on the base opposite to the adhesive surface, and wherein the base is cut out on both sides by two straight lines, and one side is cut out with a larger area than the other side. (5) The mill blank assembly according to any one of (1) to (4), wherein the uneven structure has the convex portions or the concave portions provided at or near the center of the adhesive surface. (6) The mill blank assembly according to any one of (1) to (5), wherein the uneven structure has the convex portions and the concave portions provided in a concentric shape in a plan view. (7) The mill blank assembly according to (6), wherein the uneven structure has the convex portions and the concave portions provided in a concentric circle shape in a plan view. (8) The mill blank assembly according to any one of (1) to (7), wherein the uneven structure is configured to have a circular convex portion provided at or near the center of the adhesive surface, an annular concave portion provided on the outer periphery of the circular convex portion, and an annular convex portion provided on the outer periphery of the annular concave portion. (9) The mill blank assembly according to any one of (1) to (8), wherein the adhesive layer has a thickness of 3 μm to 450 μm.(10) The mill blank assembly according to (9), wherein the thickness of the adhesive layer at the convex portion is 3 μm to 50 μm. (11) The mill blank assembly according to (9) or (10), wherein the thickness of the adhesive layer at the concave portion is 80 μm to 400 μm. (12) The mill blank assembly according to any one of (1) to (11), wherein the ratio of the contact area (S5) between the adhesive surface of the workpiece and the adhesive layer to the total area (S1) of the adhesive surface of the workpiece is 8.0% to 75.0%. (13) The mill blank assembly according to any one of (1) to (12), wherein the height of the convex portion or the depth of the concave portion is 80 μm to 400 μm. (14) The mill blank assembly according to (13), wherein the height of the convex portion or the depth of the concave portion is preferably 80 μm to 400 μm, more preferably 90 μm to 380 μm, even more preferably 100 μm to 350 μm, particularly preferably 110 μm to 250 μm, particularly preferably 130 μm to 240 μm, and most preferably 140 μm to 230 μm. (15) The mill blank assembly according to any of (1) to (14), wherein the peel adhesive strength between the adhesive surface of the workpiece and the adhesive surface of the holding portion is 100 N or more after storing at -30°C for 24 hours and then leaving to stand at room temperature for 24 hours. (16) The mill blank assembly according to any one of (1) to (15), wherein the ratio N2 / N1 of the peel adhesive strength N2 between the adhesive surface of the workpiece and the adhesive surface of the holding part after storing at -30°C for 24 hours and then leaving at room temperature for 24 hours to the peel adhesive strength N1 between the adhesive surface of the workpiece and the adhesive surface of the holding part after bonding the workpiece and the holding part and leaving them at 20°C for 24 hours is 70% or more. (17) The mill blank assembly according to any one of (1) to (16), wherein the adhesive surface of the holding part has the uneven structure, and the adhesive surface of the workpiece is flat. (18) The mill blank assembly according to any one of (1) to (17), wherein the workpiece has a Vickers hardness of 50 to 140 HV 5 / 30 as measured in accordance with JIS Z 2244:2009.(19) The mill blank assembly according to any one of (1) to (18), wherein the workpiece is made of a material containing oxide ceramics. (20) The mill blank assembly according to any one of (1) to (19), wherein the workpiece is made of a material containing at least one selected from the group consisting of zirconia, alumina, and glass ceramics. (21) The mill blank assembly according to any one of (1) to (20), wherein the holding portion is made of a material containing at least either an aluminum alloy or an iron alloy. (22) The mill blank assembly according to any one of (1) to (21), wherein the mill blank assembly is used for dental purposes.

[0117] This specification further discloses the following: (1) A mill blank assembly comprising: a workpiece; a holding part that holds the workpiece; and an adhesive layer that is disposed between the adhesive surfaces of the workpiece and the holding part and that bonds the workpiece and the holding part, wherein a contact area (S5) between the adhesive surface of the workpiece and the adhesive layer accounts for 8% to 75% of the total area (S1) of the adhesive surface of the workpiece. (2) The mill blank assembly according to (1), wherein the adhesive layer has a thickness of 5 μm to 450 μm. (3) The mill blank assembly according to (1) or (2), wherein the adhesive layer includes a first adhesive layer having a thickness of 5 μm to 50 μm and / or a second adhesive layer having a thickness of 80 μm to 400 μm. (4) The mill blank assembly according to any one of (1) to (3), wherein the height of the convex portion or the depth of the concave portion is preferably 80 μm to 400 μm, more preferably 90 μm to 380 μm, even more preferably 100 μm to 350 μm, particularly preferably 110 μm to 250 μm, particularly preferably 130 μm to 240 μm, and most preferably 140 μm to 230 μm. (5) The mill blank assembly according to any one of (1) to (4), wherein the ratio of the contact area (S5) between the adhesive surface of the workpiece and the adhesive layer to the total area (S2) of the adhesive surface of the holding portion is 10.0% to 90.0%. (6) The mill blank assembly according to any one of (1) to (5), wherein the peel adhesive strength between the adhesive surface of the workpiece and the adhesive surface of the retaining part after storage at -30°C for 24 hours is 100 N or more. (7) The mill blank assembly according to any one of (1) to (6), wherein the ratio N2 / N1 of the peel adhesive strength N2 between the adhesive surface of the workpiece and the adhesive surface of the retaining part after storage at -30°C for 24 hours and then leaving at room temperature for 24 hours to the peel adhesive strength N1 between the adhesive surface of the workpiece and the adhesive surface of the retaining part after bonding the workpiece and the retaining part and then leaving at 20°C for 24 hours is 80% or more. (8) The mill blank assembly according to any one of (1) to (7), wherein the workpiece has a Vickers hardness of 50 to 140 HV 5 / 30 as measured in accordance with JIS Z 2244:2009.(9) The mill blank assembly according to any one of (1) to (8), wherein the workpiece is made of a material containing oxide ceramics. (10) The mill blank assembly according to any one of (1) to (9), wherein the workpiece is made of a material containing at least one selected from the group consisting of zirconia, alumina, and glass ceramics. (11) The mill blank assembly according to any one of (1) to (10), wherein the holding portion is made of a material containing at least either an aluminum alloy or an iron alloy. (12) The mill blank assembly according to any one of (1) to (11), wherein the mill blank assembly is used for dental purposes. CROSS-REFERENCE TO RELATED APPLICATIONS

[0118] This application claims priority based on Japanese Patent Application No. 2023-126825, filed with the Japan Patent Office on August 3, 2023, the entire disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A mill blank assembly comprising: a workpiece; a holding part for holding the workpiece; and an adhesive layer disposed between the adhesive surfaces of the workpiece and the holding part for adhering the workpiece and the holding part, wherein at least one of the adhesive surfaces of the workpiece and the holding part has an uneven structure consisting of protrusions and recesses, and the protrusions and recesses do not fit together.

2. The mill blank assembly according to claim 1, wherein the bonding surface has an arithmetic mean roughness Ra of 0.2 μm or less as defined in JIS B0601:2013.

3. A mill blank assembly as described in claim 1, wherein the holding portion comprises a base having the adhesive surface provided on one side thereof and a support portion protruding from the side of the base opposite the adhesive surface, and at least a portion of the outer periphery of the base is formed in an arc shape centered on the support portion.

4. A mill blank assembly as described in claim 1, wherein the holding portion comprises a base having the adhesive surface provided on one side thereof and a support portion protruding from the side of the base opposite the adhesive surface, and the base is cut out on both sides by two straight lines, and one side is cut out by a larger area than the other side.

5. The mill blank assembly according to claim 1, wherein the uneven structure has the protrusions or recesses provided at or near the center of the adhesive surface.

6. The mill blank assembly according to claim 1, wherein the uneven structure has the protrusions and recesses arranged in a concentric pattern in a plan view.

7. The mill blank assembly according to claim 6, wherein the uneven structure has the protrusions and recesses arranged concentrically in a plan view.

8. The mill blank assembly according to claim 1, wherein the uneven structure is configured to have a circular protrusion provided at or near the center of the adhesive surface, an annular recess provided on the outer periphery of the circular protrusion, and an annular protrusion provided on the outer periphery of the annular recess.

9. The mill blank assembly of claim 1, wherein the adhesive layer has a thickness of 5 μm to 450 μm.

10. The mill blank assembly according to claim 1, wherein the contact area between the adhesive surface of the workpiece and the adhesive layer is 8.0% to 75.0% of the total area of ​​the adhesive surface of the workpiece.

11. The mill blank assembly according to claim 1, wherein the height of the protrusion or the depth of the recess is between 80 μm and 400 μm.

12. The mill blank assembly according to claim 1, wherein the peel adhesion strength between the adhesive surface of the workpiece and the adhesive surface of the holding part is 100 N or more after storage at -30°C for 24 hours and then leaving to stand at room temperature for 24 hours.

13. The mill blank assembly according to claim 1, wherein the ratio N2 / N1 of the peel adhesion strength N2 between the adhesive surface of the workpiece and the adhesive surface of the holding part after storing at -30°C for 24 hours and then leaving at room temperature for 24 hours to the peel adhesion strength N1 between the adhesive surface of the workpiece and the adhesive surface of the holding part after bonding the workpiece and the holding part and leaving them at 20°C for 24 hours, is 70% or more.

14. The mill blank assembly according to claim 1, wherein the adhesive surface of the holding portion has the uneven structure, and the adhesive surface of the workpiece is flat.

15. The mill blank assembly according to claim 1, wherein the workpiece has a Vickers hardness of 50 to 140 HV 5 / 30 as measured in accordance with JIS Z 2244:2009.

16. The mill blank assembly according to claim 1, wherein the workpiece is made of a material including oxide ceramics.

17. The mill blank assembly according to claim 1, wherein the workpiece is made of a material containing at least one material selected from the group consisting of zirconia, alumina, and glass ceramics.

18. The mill blank assembly according to claim 1, wherein the retaining portion is made of a material including at least one of an aluminum alloy and an iron alloy.

19. A mill blank assembly according to any one of claims 1 to 18, for dental applications.

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