Paste injector and method for mixing dental material

Abstract

In order to provide a paste injector capable of preventing leakage of paste from between a syringe and an attachment member, a paste injector (1) comprising a syringe (3) and an attachment member (M) is provided with: an outer body (OM) with which the attachment member (M) is fixed to one end of the syringe (3) by means of an engaging part (45) and an engaged part (107); an inner member (IM) which is provided inside the outer body (OM) and to which an insertion part (89, 89') to be inserted into a discharge opening (51, 51') of the syringe (3) is formed; and a biasing member (EM) sandwiched between the outer body (OM) and the inner member (IM). When the attachment member (M) is fixed to one end of the syringe (3), the biasing member (EM) is compressed between the outer body (OM) and the inner member (IM) to bias the inner member (IM) against the syringe (3).

Description

Paste injector and method for mixing dental materials

[0001] The present invention relates to a paste injector and a method for mixing dental materials.

[0002] Dental materials are known that are made up of multiple types of pastes that are mixed together immediately before use. To inject such dental materials into a predetermined location, there are paste injectors that mix and dispense multiple types of pastes.

[0003] The paste injector includes syringes that individually store multiple types of paste and an attachment member attached to the syringe outlet. The attachment member is a static mixer when the paste injector is in use, and a cap when the paste injector is stored or transported. Patent Document 1, for example, discloses a paste injector.

[0004] International Publication No. 2018 / 057503

[0005] However, when a paste injector is used, paste remains in the static mixer. The static mixer and the paste remaining in the static mixer cannot be reused because the mixed paste hardens after a certain period of time. Therefore, the static mixer must be removed (discarded) after each use, resulting in wasted paste. Therefore, static mixers are required to have a capacity sufficient to mix multiple types of paste while reducing the amount of paste remaining inside. In particular, dental paste injectors inject a smaller amount of paste per injection than paste injectors generally used for industrial purposes. Furthermore, dental paste is typically more expensive than industrial paste. For this reason, there is a stronger demand for dental paste injectors to eliminate paste loss than for industrial paste injectors.

[0006] In contrast, for example, in the case of the paste injector disclosed in Patent Document 1, the static mixer (101) has insertion portions (104, 105) that are inserted into the outlets (112, 113) of the syringes, and the paste remaining in the insertion portions (104, 105) before mixing becomes a loss. However, if the length of the insertion portion is shortened to reduce paste loss, the contact area between the outlet of the syringe and the insertion portion of the static mixer decreases, which may cause leakage of the paste from between the syringe and the static mixer.

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide a paste injector that can prevent leakage of paste from between the syringe and the mounting member.

[0008] The paste injector of the present invention comprises a syringe extending in the longitudinal direction, having a paste storage chamber inside that extends along the longitudinal direction and is filled with paste, and having an outlet formed at one end that opens one end of the paste storage chamber; an outer casing that is fixed to the one end of the syringe via an engaging structure; an inner member that is provided inside the outer casing and has an insertion portion that is inserted into the outlet of the syringe; and an attachment member that has a biasing member sandwiched between the outer casing and the inner member, wherein the biasing member is compressed between the outer casing and the inner member when the attachment member is fixed to the one end of the syringe, and biases the inner member against the syringe.

[0009] In this way, the paste injector of the present invention can prevent leakage of paste from between the syringe and the mounting member.

[0010] 4A . A front view of a paste injector of the present embodiment. An exploded perspective view of the paste injector. A cross-sectional view of a static mixer fixed to the tip portion of a syringe, cut in the width direction at a position passing through the central axis extending in the longitudinal direction. A cross-sectional view of a cap, cut in the width direction at a position passing through the central axis extending in the longitudinal direction. A front view of a syringe. A side view of a syringe. A plan view of a syringe. A bottom view of a syringe. A cross-sectional view taken along line V-V shown in FIG. 4C. An end view taken along line VI-VI shown in FIG. 4A. A perspective view of a tip portion of a syringe. A main part of the cross-sectional view taken along line VIII-VIII shown in FIG. 4C. A front view of a plunger body. A side view of a plunger body. A plan view of a plunger body. A bottom view of a plunger body. A perspective view of an elastic body holder, cut along line X-X shown in FIG. 9A. A bottom view of the elastic body holder. A cross-sectional view of an elastic body holder with an O-ring attached to an annular groove, cut in the width direction perpendicular to the longitudinal direction at the neck portion. 16B.

[0033] FIG. 16B is a cross-sectional view (schematic view) of an elastic holder with an O-ring attached to an annular groove, inserted into a paste storage chamber of a syringe, cut in a width direction perpendicular to the longitudinal direction at a neck portion, and cross-sectional views (schematic views) of the elastic holder as viewed from the front and side.

[0034] FIG. 16B is a cross-sectional view of a mixing tip main body.

[0035] FIG. 16C is a cross-sectional view of a mixer housing.

[0036] FIG. 16B is a cross-sectional view of a mixer housing.

[0037] FIG. 16C is a cross-sectional view of a mixer housing.

[0038] FIG. 16B is a cross-sectional view of a mixer exterior.

[0039] FIG. 16C is a cross-sectional view of a mixer exterior. [0039 ...A is a cross-sectional view of a mixer urging member.

[0039] FIG. 16B is a cross-sectional view of a mixer urging member.

[0039] FIG. 16B is a cross-sectional view of a mixer urging member. 22B. A cross-sectional view taken along line XXIII-XXIII shown in FIG. 22B. A perspective view of the cap inner member. A bottom view of the cap inner member. A cross-sectional view taken along line XXV-XXVV shown in FIG. 24B. A front view of the cap exterior body. A side view of the cap exterior body. A plan view of the cap exterior body. A bottom view of the cap exterior body. A perspective view of the cap exterior body.26C. A cross-sectional view taken along line XXVII-XXVII shown in FIG. 26C. A cross-sectional view taken along line XXVIII-XXVIII shown in FIG. 26C. A cross-sectional view taken along line XXIV-XXIV shown in FIG. 26A. A perspective view of a cap biasing member. A bottom view of a cap biasing member. A cross-sectional view taken along line XXXI-XXXI shown in FIG. 30B. A diagram showing a state prior to placing and fixing the static mixer over the syringe. A bottom view of the static mixer after only the mixer exterior has rotated. A cross-sectional view of the static mixer before the tip of the syringe is inserted into the static mixer. A cross-sectional view of the static mixer and syringe when the tip of the syringe is inserted into the static mixer. A cross-sectional view of the static mixer and syringe with the static mixer fixed to the tip of the syringe.

[0011] Hereinafter, an embodiment of a paste injector of the present invention will be described with reference to the drawings.

[0012] <Overall Configuration> Fig. 1 is a front view of paste injector 1, and Fig. 2 is an exploded perspective view of paste injector 1. In this embodiment, as shown in Fig. 2, a longitudinal direction (X), a width direction (Y), and a thickness direction (Z) are defined for paste injector 1.

[0013] As shown in FIG. 1 , the paste injector 1 includes a syringe 3, a plunger 5, a static mixer 7, and a guide tip 9. The paste injector 1 pushes out two types of dental pastes individually filled in the syringe 3 with the plunger 5, mixes them in the static mixer 7 just before use to prepare a dental material, and then injects the paste into a desired location (such as an affected area or a dental crown) via the guide tip 9. In other words, the paste injector 1 is a dental paste injector, and the dental material is mixed using the paste injector 1. The guide tip 9 is a nozzle member that is attached to the static mixer 7 in a fixed fit state as needed. The paste injector 1 can be used even if the guide tip 9 is not attached to the static mixer 7.

[0014] When the paste injector 1 is stored or transported, a cap 11 shown in Fig. 2 is fixed to the tip of the syringe 3 (one end 41A of a syringe body 41 described later) instead of the static mixer 7. In this specification, the static mixer 7 and cap 11 detachably attached to the tip of the syringe 3 (one end 41A of the syringe body 41) are collectively referred to as an attachment member M. The syringe 3, plunger 5, and attachment member M (static mixer 7 or cap 11) extend in the longitudinal direction X shown in Fig. 2 and are assembled with their central axes CA, which pass through the centers of the respective components, aligned.

[0015] The syringe 3 is filled with paste in advance and distributed with the plunger 5 inserted. The plunger 5 is composed of a plunger body 13, an elastic body holder 15 loosely engaged with the tip of the plunger body 13, and an annular O-ring (elastic body) 17 attached to the elastic body holder 15. Here, "loosely engaged" means that the elastic body holder 15 is engaged with the plunger body 13 with sufficient engagement force that the friction between the syringe 3 and the O-ring 17 causes the elastic body holder 15 to come off the plunger body 13. The elastic body holder 15 and the O-ring 17 form the tip of the plunger 5. Of course, the plunger 5 may be an integrated unit that is not separated into the plunger body 13 and the elastic body holder 15. In this case, the annular O-ring 17 may be attached directly to the tip of the plunger 5.

[0016] The static mixer 7 is composed of a mixing tip main body 19, a mixer housing 21, a mixer exterior body 23, and a mixer biasing member 24. In this embodiment, the static mixer 7 is disposable.

[0017] The cap 11 is composed of a cap inner member 25 , a cap outer body 27 , and a cap biasing member 28 .

[0018] [Paste Flow Path] FIG. 3A is a cross-sectional view of the static mixer 7 fixed to the tip of the syringe 3, cut in the width direction Y at a position passing through a central axis CA extending in the longitudinal direction X.

[0019] Within the static mixer 7, a paste flow path is formed by the mixing tip main body 19 and the mixer housing 21. The paste flow path is composed of a paste passage 29, a paste passage 29', an intermediate passage 31, and a mixing passage 33. The paste passages 29, 29' are aligned circumferentially about the central axis CA, are arranged symmetrically along the width direction Y, and each extend in the longitudinal direction X. The mixing passage 33 is located downstream of the paste passages 29, 29' in the paste flow direction, and extends around the central axis CA extending in the longitudinal direction X. The intermediate passage 31 connects the paste passages 29, 29' and the mixing passage 33.

[0020] The paste passage 29 is a passage through which the paste discharged from the paste storage chamber 49 of the syringe 3 flows. The paste passage 29 has an inlet hole 29A through which the paste flows and an outlet hole 29B through which the paste flows out, and is formed in the mixing tip main body 19. The opening area of ​​the inlet hole 29A is larger than the opening area of ​​the outlet hole 29B. Furthermore, the opening center point of the outlet hole 29B is set at a position closer to the central axis CA than the opening center point of the inlet hole 29A.

[0021] The inner circumferential surface of the paste passage 29 has a distal surface 29C away from the central axis CA and a proximal surface 29D close to the central axis CA when viewed in a cross section perpendicular to the thickness direction Z. A tapered portion is formed on the distal surface 29C in a region from the inlet hole 29A to a midpoint of the paste passage 29. That is, the distal surface 29C is tapered from the inlet hole 29A to a midpoint of the paste passage 29 so as to gradually approach the central axis CA as it approaches the outlet hole 29B. As shown in FIG. 15 (described later), the angle of the tapered portion, i.e., the angle θ formed by the distal surface 29C and a line C1 passing through the center point of the inlet hole 29A and extending in the longitudinal direction X, is set to 45°. The region of the distal surface 29C from the tapered portion to the outlet hole 29B extends parallel to the central axis CA and is aligned with the central axis CA.

[0022] The proximal surface 29D extends parallel to the central axis CA from the inlet hole 29A to the outlet hole 29B and is aligned with the central axis CA. In other words, the area of ​​the cross section of the paste passage 29 perpendicular to the central axis CA (longitudinal direction X) gradually decreases at a constant rate from the inlet hole 29A to a position midway along the paste passage 29, but from the position midway along the paste passage 29 to the outlet hole 29B, it is the same size as the opening area of ​​the outlet hole 29B.

[0023] In this way, the tapered portion of the distal surface 29C is formed in the region from the inlet hole 29A to a position halfway along the paste passage 29, so that the paste injector 1 can suppress the formation of air bubble accumulation within the paste passage 29, while reducing the amount of paste flowing into the paste passage 29 and also reducing the amount of paste remaining in the paste passage 29 compared to when the distal surface 29C is formed in a tapered shape that approaches the central axis CA from the inlet hole 29A to the outlet hole 29B.

[0024] The paste passage 29' is a passage through which the paste discharged from the paste storage chamber 49' of the syringe 3 flows. Since the paste passage 29' has the same configuration as the paste passage 29, the reference numerals of the respective parts of the paste passage 29 are marked with "", and the description thereof will be omitted.

[0025] The paste passages 29 and 29' are formed to have the same size and are symmetrical in the width direction Y around the central axis CA. That is, the inlet hole 29A and the inlet hole 29A' have the same opening area, and the outlet hole 29B and the outlet hole 29B' have the same opening area. When viewed along the central axis CA, the distance from the central axis CA to the center of the inlet hole 29A is the same as the distance from the central axis CA to the inlet hole 29A'. When viewed along the central axis CA, the distance from the central axis CA to the center of the outlet hole 29B is the same as the distance from the central axis CA to the outlet hole 29B'. Furthermore, the inclination angle of the tapered portion of the distal surface 29C is the same as the inclination angle of the tapered portion of the distal surface 29C'.

[0026] The intermediate passage 31 is a passage that guides the paste flowing out from the outlet holes 29B, 29B' to the joining position JP. In this embodiment, a backflow prevention wall 35 is provided between the outlet holes 29B and 29B'. The backflow prevention wall 35 divides the intermediate passage 31 into an outlet hole 29B side and an outlet hole 29B' side, and prevents paste flowing out from one outlet hole 29B (29B') from flowing into the other outlet hole 29B' (29B). Here, the backflow prevention wall 35 stands up from the end face of the mixing tip main body 19 where the outlet holes 29B, 29B' are formed, and extends along the central axis CA to the joining position JP. The backflow prevention wall 35 has curved surfaces 35A, 35A' at its base that direct the paste toward the joining position JP.

[0027] The mixing passage 33 is a passage through which the pastes that meet at the meeting point JP pass while being mixed, and extends around a central axis CA that extends in the longitudinal direction X. The mixing passage 33 is composed of an element housing portion 37 that extends cylindrically in the mixer housing 21, and an element group 39 that extends from the end of the backflow prevention wall 35 and is inserted into the element housing portion 37.

[0028] [Fixing of Mounting Member] The static mixer 7 or cap 11, which is the mounting member M, is detachably attached to the tip end of the syringe 3 (one end 41A of the syringe body 41). The configurations of the static mixer 7 and the cap 11 and their fixing structure will be described below with reference to Figures 3A and 3B. Figure 3B is a cross-sectional view of the cap 11 cut in the width direction Y at a position passing through a central axis CA extending in the longitudinal direction X.

[0029] Here, the mounting member M is composed of an inner member IM, an outer casing OM, and an urging member EM. When the mounting member M is a static mixer 7, the mixing tip main body 19 and the mixer housing 21 form the inner member IM, the mixer outer casing 23 forms the outer casing OM, and the mixer urging member 24 forms the urging member EM. When the mounting member M is a cap 11, the cap inner member 25 forms the inner member IM, the cap outer casing 27 forms the outer casing OM, and the cap urging member 28 forms the urging member EM.

[0030] 3A, in the static mixer 7, the mixing tip main body 19 and mixer housing 21 (inner member IM) are disposed inside a mixer exterior body 23 (exterior body OM). A mixer biasing member 24 (biasing member EM) is sandwiched between the mixer exterior body 23 (exterior body OM) and the mixer housing 21 (inner member IM). The mixing tip main body 19 and the mixer housing 21 are configured to be rotatable relative to the mixer exterior body 23 around a central axis CA within a predetermined angular range.

[0031] Similarly, in the cap 11, a cap inner member 25 (inner member IM) is disposed inside a cap outer body 27 (outer body OM). A cap biasing member 28 (biasing member EM) is sandwiched between the cap outer body 27 (outer body OM) and the cap inner member 25 (inner member IM). The cap inner member 25 is configured to be rotatable relative to the cap outer body 27 around a central axis CA within a predetermined angular range.

[0032] When the tip portion of the syringe 3 (one end 41A of the syringe body 41) is inserted into the exterior body OM via the inner member IM along the central axis CA, the inner member IM becomes unable to rotate relative to the syringe 3, but the exterior body OM is rotatable relative to the syringe 3. When the exterior body OM rotates around the central axis CA in this state, only the exterior body OM rotates relative to the syringe 3, and the mounting member M is fixed to the tip portion of the syringe 3 (one end 41A of the syringe body 41) via the engagement structure. At this time, the biasing member EM is compressed between the exterior body OM and the inner member IM, biasing the inner member IM against the syringe 3.

[0033] The engagement structure has three or more (three in this embodiment) engagement pairs each consisting of an engagement portion 45 formed on the syringe 3 and an engaged portion 107 formed on the mixer exterior body 23, which is the exterior body OM, or an engagement pair each consisting of an engagement portion 45 formed on the syringe 3 and an engaged portion 129 formed on the cap exterior body 27, which is the exterior body OM. The detailed configurations of the engagement portion 45, the engaged portion 107, and the engaged portion 129 will be described later.

[0034] <Details of each component> [Syringe] Fig. 4A is a front view of syringe 3, Fig. 4B is a side view, Fig. 4C is a plan view, and Fig. 4D is a bottom view. Also, Fig. 5 is a cross-sectional view taken along line V-V shown in Fig. 4C, Fig. 6 is an end view taken along line VI-VI shown in Fig. 4A, Fig. 7 is a perspective view of the tip of the syringe, and Fig. 8 is a main part of the cross-sectional view taken along line VIII-VIII shown in Fig. 4C.

[0035] The syringe 3 is a cylindrical body extending in the longitudinal direction X, and includes a syringe body 41 , two protrusions 43 , 43 ′, an engaging portion 45 , an engaging protrusion 46 , and a finger hook portion 47 .

[0036] The syringe body 41 has formed therein a plurality of (two in this example) paste storage chambers 49 and 49' filled with paste. The two paste storage chambers 49, 49' are lined up along the width direction Y inside the syringe body 41 and are formed to have the same shape. One end 41A of the syringe body 41 is formed with a circular wall portion 41a that has a circular shape when cut in the width direction Y that is perpendicular to the longitudinal direction X, and the other end 41B is formed with a finger hook portion 47.

[0037] The two protrusions 43, 43' are cylindrical portions that protrude in the longitudinal direction X from an end face of one end 41A (circular wall portion 41a) of the syringe body 41 and have respective tips that serve as outlets 51, 51'. The inner periphery of the protrusion 43 forms a part of the paste storage chamber 49, and the inner periphery of the protrusion 43' forms a part of the paste storage chamber 49'. The two protrusions 43, 43' are connected via an upright wall 41c that stands up from the circular wall portion 41a, and the inclination of the two protrusions 43, 43' is regulated.

[0038] As shown in Figures 7 and 8, a recess 41b is formed on the surface (end face of one end 41A) of the circular wall portion 41a. The recess 41b is formed between the peripheral edge of the circular wall portion 41a and the protruding portions 43, 43', and an appropriate step is provided. The formation of the recess 41b on the surface of the circular wall portion 41a prevents the occurrence of sink marks when the syringe 3 is molded from resin. Furthermore, preventing the occurrence of sink marks can suppress tilting of the protruding portions 43, 43'.

[0039] The engaging portion 45 constitutes an engaging structure that fixes the mounting member M to the tip end portion of the syringe 3 (one end portion 41A of the syringe body 41), and is a portion that engages with the engaged portions (engaged portions 107 and 129) of the mounting member M (the static mixer 7 and the cap 11). As shown in Fig. 4C, the engaging portion 45 is composed of three protruding pieces 45A, 45B, and 45C formed on the outer circumferential surface of the circular wall portion 41a of the syringe body 41.

[0040] The protrusions 45A, 45B, and 45C are aligned along the rotation direction of the outer casing OM and are asymmetrical about the central axis CA, which is the center of rotation of the outer casing OM, when viewed along the central axis CA. Note that "point symmetry" generally refers to a shape that overlaps with the original shape when rotated 180° about the point of symmetry, but "asymmetrical" here refers to a shape that does not overlap with the original shape when the syringe 3 is rotated about the central axis CA, except when rotated 360°.

[0041] The protrusions 45A, 45B, and 45C are arranged at unequal intervals along the rotational direction of the outer casing OM. Here, the distance in the rotational direction from protrusion 45A to protrusion 45B is the same as the distance in the rotational direction from protrusion 45A to protrusion 45C. On the other hand, the distance in the rotational direction from protrusion 45B to protrusion 45C is shorter than the distance from protrusion 45A to protrusion 45B and the distance from protrusion 45A to protrusion 45C.

[0042] Furthermore, the protrusions 45A, 45B, and 45C have different shapes when viewed along the central axis CA. That is, the length of the protrusion 45A in the rotational direction is longer than the lengths of the protrusions 45B and 45C in the rotational direction. On the other hand, the lengths of the protrusions 45B and 45C in the rotational direction are the same, but the directions in which they protrude from the outer circumferential surface of the circular wall portion 41a are different.

[0043] The protrusions 45B and 45C are symmetrical with respect to a symmetry axis AS that passes through the central axis CA and the circumferential center position of the protrusion 45A.

[0044] The engaging protrusion 46, together with the engaging portion 45, constitutes an engaging structure that fixes the mounting member M to the tip end portion of the syringe 3 (one end portion 41A of the syringe body 41), and is a portion that engages with the engaged portions (engaged portions 108 and 130) of the mounting member M (the static mixer 7 and the cap 11). In this embodiment, as shown in Figures 4A to 4C, the engaging protrusion 46 is provided at a position on the paste storage chamber 49' side of one end portion 41A of the syringe body 41 so as to extend from the outer circumferential surface of the syringe body 41 in the width direction Y.

[0045] The finger hook 47 is a flange-shaped portion extending in the width direction Y and thickness direction Z from the outer peripheral surface of the other end 41B of the syringe body 41. As shown in FIGS. 4C and 4D , the outer peripheral shape of the finger hook 47 is generally hexagonal. Note that the surface 47a of the finger hook 47 on at least one end 41A side may be textured. By textured the surface 47a, it is possible to prevent fingers from slipping during use and to make gate marks less noticeable, thereby improving the appearance quality.

[0046] As shown in FIG. 6, the outer circumferential surface of the syringe body 41 has a pair of widthwise outer circumferential surfaces 57, 57', a pair of thicknesswise outer circumferential surfaces 59, 59', and four connecting outer circumferential surfaces 61.

[0047] The pair of widthwise outer peripheral surfaces 57, 57' are surfaces of the outer peripheral surface of the syringe body 41 that are located on opposite sides along the thickness direction Z. Each of the widthwise outer peripheral surfaces 57, 57' has a flat portion 57A that is flat along the longitudinal direction X and the width direction Y. Each of the widthwise outer peripheral surfaces 57, 57' has a groove-like recessed portion 57B that extends in the longitudinal direction X and is recessed more than the flat portion 57A. The recessed portion 57B is located between two paste storage chambers 49, 49' formed inside the syringe body 41, and the flat portion 57A is divided into two by the recessed portion 57B along the width direction Y. Each recessed portion 57B has a wedge-shaped cross section whose length in the width direction Y gradually narrows as it becomes deeper.

[0048] The pair of thickness direction outer peripheral surfaces 59, 59' are surfaces of the outer peripheral surface of the syringe body 41 that are located on opposite sides along the width direction Y. The thickness direction outer peripheral surfaces 59, 59' are curved outward in the width direction Y with a predetermined radius of curvature, which is set to a curved surface of R5 in this example.

[0049] The connecting outer peripheral surface 61 is a surface of the outer peripheral surface of the syringe body 41 that is respectively set between the width direction outer peripheral surface 57 and the thickness direction outer peripheral surface 59, between the width direction outer peripheral surface 57' and the thickness direction outer peripheral surface 59, between the width direction outer peripheral surface 57 and the thickness direction outer peripheral surface 59', and between the width direction outer peripheral surface 57' and the thickness direction outer peripheral surface 59'. The connecting outer peripheral surface 61 is curved with a predetermined radius of curvature (e.g., radii of curvature R1 to R5, R2.5 in this embodiment) and smoothly connects the width direction outer peripheral surface 57 and the thickness direction outer peripheral surface 59, the width direction outer peripheral surface 57' and the thickness direction outer peripheral surface 59, the width direction outer peripheral surface 57 and the thickness direction outer peripheral surface 59', and the width direction outer peripheral surface 57' and the thickness direction outer peripheral surface 59'. The connecting outer peripheral surface 61 and the pair of thickness direction outer peripheral surfaces 59, 59' are formed by combining multiple curved surfaces set to different radii of curvature. The connecting outer peripheral surface 61 and the pair of thickness direction outer peripheral surfaces 59, 59' may be formed by curved surfaces set to the same radius of curvature.

[0050] The paste storage chamber 49 has a discharge port 51 at one end 49A (protruding portion 43) that opens one end of the paste storage chamber 49 and through which paste pushed out by the plunger 5 is discharged, and a filling port 53 at the other end 49B that opens the other end of the paste storage chamber 49. The paste storage chamber 49 has a tapered shape at one end 49A that fits over the tip end of the plunger 5 (top portion 83 of the elastic holder 15) inserted into the paste storage chamber 49. In addition, a retaining projection 55 is provided on the inner peripheral surface of the other end 49B to prevent the plunger 5 inserted into the paste storage chamber 49 from falling out. Note that the paste storage chamber 49' has a similar configuration to the paste storage chamber 49, and therefore the same reference numerals as those of the paste storage chamber 49 are used and description thereof will be omitted.

[0051] 6, the cross section of the paste storage chamber 49 taken in a direction perpendicular to the longitudinal direction X has an elliptical shape in which the major axis direction LA is aligned with the thickness direction Z and the minor axis direction SA is aligned with the width direction Y. Note that the term "elliptical shape" is a concept that includes not only an elliptical shape defined geometrically, but also shapes that approximate an ellipse, such as an oval (a shape formed by connecting two semicircles with two straight lines), an elliptical arch shape (a shape formed by cutting out a portion of an ellipse along a straight line), an oblate ellipse (a shape formed by flattening an ellipse in the major axis or minor axis direction), and an oval shape. In this embodiment, the inner peripheral surface of the paste storage chamber 49 is composed of a pair of inner flat surface portions 63, 63' that are flat along the longitudinal direction X and the thickness direction Z, and a pair of inner curved surface portions 65, 65' that are curved at a predetermined curvature.

[0052] The pair of inner flat surface portions 63, 63' face each other in the width direction Y, sandwiching the internal space of the paste storage chamber 49 therebetween. The pair of inner curved surface portions 65, 65' face each other in the thickness direction Z, sandwiching the internal space of the paste storage chamber 49 therebetween, and smoothly connect the pair of inner flat surface portions 63, 63'. As a result, in this embodiment, the cross-sectional shape of the inner peripheral surface of the paste storage chamber 49 presents an oblate ellipse.

[0053] In this embodiment, the length dimension T1 in the major axis direction LA of the elliptical shape of the inner peripheral surface of the paste storage chamber 49 is preferably in the range of 1.1 to 2.0, where the length dimension W1 in the minor axis direction SA is 1. In this embodiment, the length dimension T1 in the major axis direction LA is set to 1.3, where the length dimension W1 in the minor axis direction SA is 1. Specifically, the length dimension T1 in the major axis direction LA is preferably 5 mm to 20 mm, and the length dimension W1 in the minor axis direction SA is preferably 4.5 mm to 10 mm.

[0054] [Plunger Body] Fig. 9A is a front view of the plunger body 13, Fig. 9B is a side view, Fig. 9C is a plan view, and Fig. 9D is a bottom view. Also, Fig. 10 is a cross-sectional view taken along line XX shown in Fig. 9A.

[0055] The plunger body 13 includes a pressing portion 67 and two rod-shaped portions 69 and 69'.

[0056] The pressing portion 67 is a portion that a user presses with a finger (e.g., a thumb) when holding the syringe 3 between two fingers (e.g., an index finger and a middle finger) and placing the fingers on the finger hook portion 47 to push the plunger 5 into the syringe 3. As shown in FIG. 9D , the pressing portion 67 has an outer circumferential shape that is elliptical in the thickness direction Z, and two rod-shaped portions 69, 69′ are arranged side by side in the width direction Y at the center of the thickness direction Z. As a result, the plunger body 13 of the present embodiment is less likely to have a difference in distance from the position where force is concentrated when the user presses the pressing portion 67 to the two rod-shaped portions 69, 69′, compared to a plunger body in which the outer circumferential shape of the pressing portion is elliptical in the width direction Y and the two rod-shaped portions 69, 69′ are arranged side by side in the width direction Y at the center of the thickness direction Z. Therefore, the force of the user pressing the pressing portion 67 is easily transmitted approximately evenly to each of the rod-shaped portions 69, 69', and the plunger body 13 of this embodiment can make the amount of paste discharged from the paste storage chamber 49 and the amount of paste discharged from the paste storage chamber 49' approximately equal. Furthermore, the bottom surface of the pressing portion 67 is curved in the direction in which the rod-shaped portions 69, 69' extend so that the user can easily press the pressing portion 67 with their fingers.

[0057] The rod-shaped portions 69, 69' are rod-shaped portions extending in parallel from the pressing portion 67 along the longitudinal direction X. In this embodiment, the rod-shaped portions 69, 69' are lined up at a predetermined interval along the major axis direction (width direction Y) of the pressing portion 67, and are simultaneously inserted into the paste storage chambers 49, 49', respectively. Here, the rod-shaped portion 69 and the rod-shaped portion 69' have the same shape, and both can be inserted into both the paste storage chambers 49, 49'. In other words, when the rod-shaped portion 69 is inserted into the paste storage chamber 49, the rod-shaped portion 69' is inserted into the paste storage chamber 49', and when the rod-shaped portion 69 is inserted into the paste storage chamber 49', the rod-shaped portion 69' is inserted into the paste storage chamber 49.

[0058] As shown in FIG. 10 , the rod-shaped portion 69 has a cross-shaped cross section in the width direction Y, which is formed by combining a thickness direction wall portion 71A extending in the thickness direction Z and a width direction wall portion 71B extending in the width direction Y. The length dimension α of the thickness direction wall portion 71A in the thickness direction Z is greater than the length dimension β of the width direction wall portion 71B in the width direction Y. When the rod-shaped portion 69 is inserted into the paste storage chamber 49 (49′), the intersection position of the thickness direction wall portion 71A and the width direction wall portion 71B is located at the center of the paste storage chamber 49 (49′). Furthermore, the length dimension α of the thickness direction wall portion 71A in the thickness direction Z is slightly shorter than the maximum length of the paste storage chamber 49 (49′) in the major axis direction LA, and the length dimension β of the width direction wall portion 71B in the width direction Y is slightly shorter than the maximum length of the paste storage chamber 49 (49′) in the minor axis direction SA. As a result, when the rod-shaped portion 69 is inserted into the paste storage chamber 49 (49'), the tip of the thickness-wise wall portion 71A lies along the inner curved surface portions 65, 65' of the paste storage chamber 49 (49'), and the tip of the width-wise wall portion 71B lies along the inner flat surface portions 63, 63' of the paste storage chamber 49 (49').

[0059] 9A , the rod-shaped portion 69 has a pair of protrusions 73, 73 formed to protrude in the width direction Y and a pair of cutouts 75, 75 formed at one end of the width direction wall 71B in the longitudinal direction X. As a result, when the rod-shaped portion 69 is inserted into the paste storage chamber 49 (49′), the pair of protrusions 73, 73 of the width direction wall 71B come into contact with the inner flat surface portions 63, 63′, and the portion of the width direction wall 71B where the pair of cutouts 75, 75 are formed is bent. This positions the rod-shaped portion 69 in the width direction Y and prevents rattling. Similarly, in order to prevent rattling of the rod-shaped portion 69, a plurality of protrusions 77 are formed at a predetermined interval in the longitudinal direction X at the tip of each of the thickness direction wall 71A and the width direction wall 71B.

[0060] The rod-shaped portion 69 has a holder engagement portion 79 formed at its tip with which the elastic body holder 15 loosely engages. The holder engagement portion 79 includes a tip wall portion 79A that contacts the bottom surface 81A of the elastic body holder 15, and an engagement protrusion 79B that extends from the tip wall portion 79A in the longitudinal direction X and is inserted into an engagement hole 81B formed in the bottom surface 81A of the elastic body holder 15. As shown in FIG. 9C , the outer peripheral shape of the tip wall portion 79A is elliptical in shape to match the cross-sectional shape of the paste storage chamber 49 (49′). When the rod-shaped portion 69 is inserted into the paste storage chamber 49 (49′), if the protrusions 73, 73 and the protrusion 77 climb over the removal prevention protrusions 55 (55′), the removal prevention protrusions 55 (55′) catch on the protrusions 73, etc., preventing the plunger 5 from falling out.

[0061] The rod-shaped portion 69 is provided with a plurality of reinforcing ribs 78 at predetermined intervals along the longitudinal direction X to reinforce the rod-shaped portion 69. In this embodiment, five reinforcing ribs 78 are provided on the rod-shaped portion 69 in order from the tip side thereof: a first reinforcing rib 78A, a second reinforcing rib 78B, a third reinforcing rib 78C, a fourth reinforcing rib 78D, and a fifth reinforcing rib 78E. Each of the first reinforcing rib 78A to the fifth reinforcing rib 78E is formed across the gap between the thickness direction wall portion 71A and the width direction wall portion 71B. As a result, the cross-sectional shape of each of the first reinforcing rib 78A to the fifth reinforcing rib 78E taken orthogonally to the longitudinal direction X is smaller than the cross-sectional shape of the paste storage chamber 49 taken orthogonally to the longitudinal direction X, and is similar to the cross-sectional shape of the paste storage chamber 49.

[0062] In this embodiment, the first reinforcing rib 78A is formed 9 mm away from the tip wall portion 79A. The second reinforcing rib 78B is formed 27.6 mm away from the tip wall portion 79A. The third reinforcing rib 78C is formed 41.2 mm away from the tip wall portion 79A. The fourth reinforcing rib 78D is formed 54.7 mm away from the tip wall portion 79A. The fifth reinforcing rib 78E is formed 64.7 mm away from the tip wall portion 79A. In other words, when the distance between the second reinforcing rib 78B and the third reinforcing rib 78C is taken as the reference distance, the distance between the first reinforcing rib 78A and the second reinforcing rib 78B is slightly longer, the distance between the third reinforcing rib 78C and the fourth reinforcing rib 78D is approximately the same, and the distance between the fourth reinforcing rib 78D and the fifth reinforcing rib 78E is shorter.

[0063] Each of the second reinforcing rib 78B to the fifth reinforcing rib 78E also functions as an indicator that shows the remaining amount of paste in the paste storage chamber 49 when the rod-shaped portion 69 is inserted into the paste storage chamber 49. That is, when the paste injector 1 is shipped, the paste storage chambers 49, 49' of the syringe 3 are filled with different types of paste in amounts sufficient for multiple uses (approximately 15 uses in this example), and the plunger 5 is inserted into the filling port 53, 53' of the syringe 3 and sealed (see FIG. 1). When the plunger 5 is pushed into the syringe 3, the elastic holder 15 (15') to which the O-ring 17 (17') is attached moves within the paste storage chamber 49 (49') toward the discharge port 51 (51'), and the paste is discharged from the paste storage chamber 49 (49').

[0064] At this time, as the paste is used, the plunger 5 moves within the syringe 3 toward the discharge port 51, 51', and the reinforcing rib 78 (78') overlapping the filling port 53 (53') changes in order from the second reinforcing rib 78B (78B'), to the third reinforcing rib 78C (78C'), to the fourth reinforcing rib 78D (78D'), and to the fifth reinforcing rib 78E (78E'). In other words, the type of reinforcing rib 78 (78') overlapping the filling port 53 (53') changes depending on the amount of paste remaining in the paste storage chamber 49 (49'). Therefore, the paste injector 1 of this embodiment can indicate the amount of paste remaining in the paste storage chamber 49 (49') by the reinforcing rib 78 (78') located at a position overlapping the filling port 53 (53').

[0065] Specifically, in this embodiment, when the remaining amount of paste is approximately 75%, the second reinforcing rib 78B (78B') overlaps with the filling port 53 (53'). When the remaining amount of paste is approximately 50%, the third reinforcing rib 78C (78C') overlaps with the filling port 53 (53'). When the remaining amount of paste is approximately 25%, the fourth reinforcing rib 78D (78D') overlaps with the filling port 53 (53'). When the remaining amount of paste is enough for one use, the fifth reinforcing rib 78E (78E') is positioned so as to overlap with the filling port 53 (53').

[0066] The rod-shaped portion 69' has the same configuration as the rod-shaped portion 69, and therefore the reference numerals of the respective parts of the rod-shaped portion 69 are marked with "'" and the description thereof will be omitted.

[0067] [Elastic Body Holder] FIG. 11A is a perspective view of the elastic body holder 15, and FIG. 11B is a bottom view thereof.

[0068] The elastic holder 15 is loosely engaged with each of the holder engaging portions 79, 79' at the tip of the plunger body 13, constituting the tip of the plunger 5. The elastic holder 15 has a body portion 81, a top portion 83, and a neck portion 85. The body portion 81 has an elliptical cross section in the width direction Y. The bottom surface 81A of the body portion 81 has an engaged hole 81B into which the engaging protrusion 79B of the holder engaging portion 79 or the engaging protrusion 79B' of the holder engaging portion 79' is inserted. The outer peripheral surface 81C of the body portion 81 has an elliptical shape that follows the elliptical shape of the inner peripheral surface (inner flat surface portions 63, 63' and inner curved surface portions 65, 65') of the paste storage chamber 49 (49'). The top portion 83 has a shape that tapers toward the tip. The neck portion 85 is an elliptical portion formed between the body portion 81 and the top portion 83. The neck portion 85 and the body portion 81 and top portion 83 that face each other across the neck portion 85 form an annular groove portion 81D in which the O-ring 17 is attached.

[0069] The elliptical shape of the body portion 81 is smaller than the cross-sectional shape of the paste storage chamber 49 (49'), and is similar to the cross-sectional shape of the paste storage chamber 49 (49'), conforming to the elliptical shape of the inner peripheral surface of the paste storage chamber 49 (49'). Therefore, when the elastic holder 15 is inserted into the paste storage chamber 49 (49'), the distance from the outer peripheral surface 81C of the body portion 81 to the inner peripheral surface of the paste storage chamber 49 (49') is constant around the entire circumference of the body portion 81. Furthermore, in this embodiment, similar to the paste storage chamber 49 (49'), the length dimension T2 in the major axis direction of the elliptical shape of the body portion 81 is preferably in the range of 1.1 to 2.0, where the length dimension W2 in the minor axis direction is 1. Specifically, in this embodiment, the length dimension T2 in the major axis direction is set to 1.3, where the length dimension W2 in the minor axis direction is 1.

[0070] The elliptical shape of the neck portion 85 is smaller than the elliptical shape of the body portion 81 and has a cross-sectional shape similar to the elliptical shape of the body portion 81. In other words, the elliptical shape of the neck portion 85 has a cross-sectional shape similar to the cross-sectional shape of the paste storage chamber 49 (49'). Therefore, when the elastic body holder 15 is inserted into the paste storage chamber 49 (49'), the distance from the outer peripheral surface 85C of the neck portion 85 to the inner peripheral surface of the paste storage chamber 49 (49') is constant over the entire circumference of the neck portion 85. Furthermore, in this embodiment, the ratio of the length dimension in the major axis direction to the length dimension in the minor axis direction of the elliptical shape of the neck portion 85 is set to the same ratio as the elliptical shape of the body portion 81.

[0071] FIG. 12 is a cross-sectional view of the elastic holder 15 with the O-ring 17 attached to the annular groove 81D, taken along the width direction Y perpendicular to the longitudinal direction X at the neck portion 85. Here, the O-ring 17 is annular, but the neck portion 85 is elliptical. Therefore, when the O-ring 17 is attached to the annular groove 81D, it is stretched in the major axis direction (thickness direction Z) and becomes elliptical. The length dimension T3 of the elliptical O-ring 17 in the major axis direction is greater than the length dimension T2 of the elliptical shape of the body portion 81. Furthermore, the length dimension W3 of the elliptical O-ring 17 in the minor axis direction is greater than the length dimension W2 of the elliptical shape of the body portion 81. Therefore, the O-ring 17 is fixed while protruding from the annular groove 81D.

[0072] Furthermore, a stronger tensile force acts on region a of the O-ring 17, which is stretched in the longitudinal direction (thickness direction Z), than on region b, which is not stretched in the longitudinal direction (thickness direction Z). As a result, as shown in FIG. 12 , the wire diameter ΔA of the O-ring 17 in region a is thinner than the wire diameter ΔB in region b, and the wire diameter of the O-ring 17 varies depending on the circumferential position. Note that the "wire diameter of the O-ring 17" refers to the cross-sectional thickness of the O-ring 17. Because the wire diameter of the O-ring 17 varies depending on the circumferential position, the amount of protrusion of the O-ring 17 from the annular groove 81D varies, and the thinner the wire diameter (e.g., region a), the less the O-ring 17 protrudes from the annular groove 81D.

[0073] Furthermore, the length T3 in the major axis direction of the elliptical O-ring 17 is slightly larger than the length T1 in the major axis direction of the elliptical shape of the inner peripheral surface of the paste storage chamber 49 or the paste storage chamber 49'. Also, the length W3 in the minor axis direction of the elliptical O-ring 17 is slightly larger than the length W1 in the minor axis direction of the elliptical shape of the inner peripheral surface of the paste storage chamber 49 or the paste storage chamber 49'. Therefore, when the elastic body holder 15 is inserted into the paste storage chamber 49 (49') of the syringe 3, the O-ring 17 comes into contact with the inner peripheral surface of the paste storage chamber 49 (49') and is compressed between the inner peripheral surface of the paste storage chamber 49 (49') and the outer peripheral surface 85C of the neck portion 85.

[0074] 13 shows a cross-sectional view (schematic diagram) of the elastic holder 15 with the O-ring 17 attached to the annular groove 81D inserted into the paste storage chamber 49 of the syringe 3, cut at the neck portion 85 in the width direction Y perpendicular to the longitudinal direction X, and cross-sectional views (schematic diagrams) of the elastic holder 15 as viewed from the front and side. In FIG. 13, the portion of the O-ring 17 that protrudes from the annular groove 81D and is compressed when inserted into the paste storage chamber 49 is shown in gray, and the state of the O-ring 17 before compression is shown by a dashed line.

[0075] 13, when the plunger 5 is inserted into the syringe 3 with the O-ring 17 attached to the annular groove 81D, the O-ring 17 is sandwiched and compressed between the inner circumferential surface (inner flat surface portions 63, 63' and inner curved surface portions 65, 65') of the paste storage chamber 49 and the outer circumferential surface 85C of the neck portion 85. Here, the wire diameter of the O-ring 17 varies depending on the circumferential position, and the thinner the wire diameter, the less the amount of protrusion from the annular groove 81D.

[0076] 13 , the magnitude of the difference (ΔX1, ΔX2) between the distance Gd from the outer peripheral surface 85C of the neck portion 85 to the inner peripheral surface of the paste storage chamber 49 and the wire diameter Wr of the O-ring 17 varies depending on the circumferential position of the O-ring 17. Therefore, the compression rate of the O-ring 17 when inserted into the paste storage chamber 49 varies depending on the circumferential position.

[0077] That is, in the elliptical O-ring 17, the region b with a thick wire diameter protrudes more from the annular groove portion 81D than the region a with a thin wire diameter, and the difference ΔX2 in the region b is larger than the difference ΔX1 in the region a. Therefore, when the O-ring 17 is inserted into the syringe 3, the region b of the O-ring 17 is pressed more toward the inside of the paste storage chamber 49 than the region a, and the compression rate in the region b is larger than the compression rate in the region a. As a result, the compression rate in the major axis direction (thickness direction Z) of the elliptical O-ring 17 is larger than the compression rate in the minor axis direction (width direction Y) of the O-ring 17.

[0078] Furthermore, since the compression rate of the O-ring 17 varies depending on the circumferential position, the frictional force generated between the O-ring 17 and the inner peripheral surface of the paste storage chamber 49 (49') varies depending on the circumferential position of the O-ring 17. That is, the frictional force between the apex 17A of the O-ring 17 in the major axis direction, which is stretched into an elliptically shape, and the inner peripheral surface of the paste storage chamber 49 (49') is greater than the frictional force between the apex 17B of the O-ring 17 in the minor axis direction, which is stretched into an elliptically shape, and the inner peripheral surface of the paste storage chamber 49 (49'). Therefore, by adjusting the major axis dimensions of the elliptical cross-sectional shape of the paste storage chamber 49 (49') and the elliptical cross-sectional shape of the plunger 5 relative to the minor axis dimensions, it is easy to adjust the ease of movement of the plunger 5 in the longitudinal direction while maintaining the seal between the inner peripheral surface of the paste storage chamber 49 (49') and the elastic body (O-ring 17).

[0079] Furthermore, it is preferable that the compression ratio in the major axis direction of the O-ring 17 (compression ratio in region b) is approximately 10 to 14%, and the compression ratio in the minor axis direction (compression ratio in region a) is approximately 3 to 7%. Specifically, in this embodiment, the compression ratio in the major axis direction is 12%, and the compression ratio in the minor axis direction is 5%. The compression ratio C (%) is calculated by the following formula: C = (Wr - Gd) / Wr x 100, where Wr: wire diameter of the elastic body (O-ring) [mm], Gd: distance from the outer peripheral surface of the neck portion to the inner peripheral surface of the paste storage chamber [mm].

[0080] The elastic body holder 15 is loosely engaged with the holder engaging portion 79 (79') at the tip of the plunger body 13. Therefore, when the elastic body holder 15, with the O-ring 17 attached, is inserted into the paste storage chamber 49 (49') of the syringe 3 together with the plunger body 13, the plunger body 13 is pushed in, and the elastic body holder 15 moves together with the plunger body 13 in the longitudinal direction X within the paste storage chamber 49 (49'). On the other hand, when the plunger body 13 is pulled back, the elastic body holder 15 is separated from the plunger body 13 and is left behind in the paste storage chamber 49 (49'). This prevents air from being drawn into the paste storage chamber 49 (49') through the discharge ports 51, (51') even if the plunger 5 is accidentally pulled back.

[0081] [Static Mixer] (Mixing Tip Main Body) Fig. 14A is a perspective view of the mixing tip main body 19, and Fig. 14B is a bottom view. Fig. 15 is a cross-sectional view taken along line XV-XV shown in Fig. 14B.

[0082] The mixing tip main body 19 is a member that, in combination with the mixer housing 21, constitutes the inner member IM of the static mixer 7, which is the mounting member M. The mixing tip main body 19 includes a base 87, two insertion portions 89, 89', a pair of rotational engagement pieces 91, 91', a backflow prevention wall 35, and an element group 39.

[0083] The base 87 is a cylindrical portion that fits inside the mixer exterior body 23, which is the exterior body OM. A flange portion 87C extending radially outward is formed on the outer periphery of the base 87. The flange portion 87C fits into a groove (circumferential groove 103) formed on the inner circumferential surface of the mixer exterior body 23, which will be described later, and the mixing tip main body 19 is fixed to the mixer exterior body 23 in a state that allows relative rotation about the central axis CA.

[0084] The two insertion portions 89, 89' and the pair of rotary engagement pieces 91, 91' are formed on a first end surface 87A of the base 87 facing the syringe 3, and extend from the first end surface 87A in the longitudinal direction X. When the static mixer 7 is attached to the syringe 3, the two insertion portions 89, 89' are inserted into the two protrusions 43, 43' of the syringe 3, respectively. A paste passage 29 is formed inside the insertion portion 89, and a paste passage 29' is formed inside the insertion portion 89'. The pair of rotary engagement pieces 91, 91' are portions that respectively engage with engagement grooves (a pair of first engagement grooves 105A, 105A' or a pair of second engagement grooves 105B, 105B') of the mixer exterior body 23, which will be described later.

[0085] The backflow prevention wall 35 extends along the central axis CA from the center of the second end face 87B opposite the first end face 87A of the base 87. The tip of the backflow prevention wall 35 is the paste joining position JP, and the element group 39 extends from the tip of the backflow prevention wall 35. The element group 39 is made up of a plurality of elements (eight in this embodiment) lined up along the central axis CA.

[0086] The paste passage 29 is formed continuously penetrating the insertion portion 89 and the base portion 87. The inlet hole 29A is formed in the end face of the insertion portion 89, and the outlet hole 29B is formed in the second end face 87B of the base portion 87. Similarly, the paste passage 29' is formed continuously penetrating the insertion portion 89' and the base portion 87. The inlet hole 29A' is formed in the end face of the insertion portion 89', and the outlet hole 29B' is formed in the second end face 87B of the base portion 87.

[0087] As described above, the inner peripheral surface of the paste passage 29 has a distal surface 29C that is far from the central axis CA and a proximal surface 29D that is close to the central axis CA when viewed in a cross section perpendicular to the thickness direction Z. The angle θ formed by the distal surface 29C and a line C1 that passes through the center point of the inlet hole 29A and extends in the longitudinal direction X is set to 45° here.

[0088] (Mixer Housing) Fig. 16A is a perspective view of the mixer housing 21, Fig. 16B is a bottom view, and Fig. 17 is a cross-sectional view taken along line XVII-XVII shown in Fig. 16B.

[0089] The mixer housing 21 is a member that, in combination with the mixing tip main body 19, constitutes the inner member IM of the static mixer 7, which is the mounting member M. The mixer housing 21 includes a base housing portion 93 and an element housing portion 37.

[0090] The base housing portion 93 includes a circular end wall portion 93A that covers the second end face 87B of the base 87 of the mixing tip main body portion 19 when the mixer housing 21 is placed over the mixing tip main body portion 19, and a peripheral wall portion 93B that rises from the edge of the end wall portion 93A, surrounds the base 87, and extends until its tip contacts the flange portion 87C.

[0091] A recess 93C is provided on the inner wall of the end wall portion 93A at a position opposite the outlet holes 29B, 29B'. By fitting the mixer housing 21 onto the mixing tip body 19, an intermediate passage 31 is formed inside the inner member IM, which is partitioned by the base 87, the backflow prevention wall 35, and the recess 93C (see FIG. 3).

[0092] The element housing portion 37 is a cylindrical portion with an open tip that extends in the longitudinal direction X from a through-hole formed in the center of the end wall portion 93A of the base housing portion 93. When the mixer housing 21 is placed over the mixing tip body 19, the element group 39 is inserted into the element housing portion 37 to form the mixing passage 33. A guide tip engagement groove 37A for fixing the guide tip 9 is formed on the outer periphery of the element housing portion 37.

[0093] (Mixer exterior body) Fig. 18A is a front view of the mixer exterior body 23, Fig. 18B is a side view, Fig. 18C is a plan view, Fig. 18D is a bottom view, and Fig. 18E is a perspective view. Also, Fig. 19 is a cross-sectional view taken along line XIX-XIX shown in Fig. 18C, Fig. 20 is a cross-sectional view taken along line XX-XX shown in Fig. 18C, and Fig. 21 is a cross-sectional view taken along line XXI-XXI shown in Fig. 18A.

[0094] The mixer exterior 23 is a cylindrical member that constitutes the exterior OM of the static mixer 7, which is the mounting member M. The static mixer 7, which is the mounting member M, is constituted by accommodating the inner member IM, which is made up of the mixing tip main body 19 and the mixer housing 21, and the mixer biasing member 24, inside the mixer exterior 23. The mixer exterior 23 also rotates relatively to the syringe 3 about the central axis CA.

[0095] The mixer exterior 23 includes a top wall 95 having a regular hexagonal outer periphery, a first peripheral wall 97 rising from the edge of the top wall 95, and a second peripheral wall 99 extending continuously from the first peripheral wall 97 via a step. The interior of the mixer exterior 23 defines a first space S1 surrounded by the top wall 95 and the first peripheral wall 97, and a second space S2 surrounded by the second peripheral wall 99 (see FIGS. 19 and 20 ). The mixer biasing member 24 and the inner member IM, which are comprised of the mixing tip main body 19 and the mixer housing 21, fit into the first space S1 in a rotatable manner about the central axis CA. The tip of the syringe 3 (one end 41A of the syringe body 41) is inserted into the second space S2 with the inner member IM housed therein (see FIG. 3 ).

[0096] The top wall 95 covers the end wall 93A of the mixer housing 21 via the mixer biasing member 24 and faces the opening through which the syringe 3 is inserted (see FIG. 3 ). A top penetration tube 101 is formed in the center of the top wall 95 to expose the element housing 37 to the outside. The top penetration tube 101 is a cylindrical portion that protrudes from the top wall 95 and penetrates the top wall 95. When the inner member IM consisting of the mixing tip main body 19 and the mixer housing 21 is housed in the mixer exterior 23, the element housing 37 penetrates the top penetration tube 101. An arrow AR1 indicating the position of a recess 107A (described later) is engraved on the surface of the top wall 95 (see FIG. 16B ). The recess 107A is one of the engagement portions 107 (described later).

[0097] As shown in Fig. 18C, the outer peripheral surface of the first circumferential wall portion 97 has a regular hexagonal shape when viewed along the central axis CA. As shown in Fig. 18D, the inner peripheral surface of the first circumferential wall portion 97 has a circular shape when viewed along the central axis CA. The inner peripheral surface of the first circumferential wall portion 97 is formed with a circumferential groove 103, a pair of first engaged grooves 105A, 105A', and a pair of second engaged grooves 105B, 105B'.

[0098] As shown in FIG. 3, the circumferential groove 103 is a recess into which the flange portion 87C of the mixing tip body 19 fits, and extends in the circumferential direction (the rotation direction of the inner member IM).

[0099] The first engaged groove 105A and the second engaged groove 105B on one side are recesses with which one of the rotary engaging pieces 91 engages. The first engaged groove 105A' and the second engaged groove 105B' on the other side are recesses with which the other of the rotary engaging pieces 91' engages. The pair of first engaged grooves 105A, 105A' and the pair of second engaged grooves 105B, 105B' are arranged side by side in the circumferential direction (the direction of rotation of the inner member IM) at a predetermined interval. Here, the pair of first engaged grooves 105A, 105A' are formed in positions facing each other in the thickness direction Z across the central axis CA. The pair of second engaged grooves 105B, 105B' are formed in positions facing each other in a direction offset in the circumferential direction from the thickness direction Z across the central axis CA.

[0100] When assembled into the static mixer 7, the mixing tip main body 19 and the mixer housing 21 rotate relative to the mixer exterior body 23 around the central axis CA. At this time, depending on the positional relationship in the rotational direction between the mixing tip main body 19 and the mixer housing 21 and the mixer exterior body 23, one rotational engagement piece 91 engages with either the first engaged groove 105A or the second engaged groove 105B, and the other rotational engagement piece 91' engages with either the first engaged groove 105A' or the second engaged groove 105B'. This determines the relative rotational position of the mixing tip main body 19 and the mixer housing 21 and the mixer exterior body 23.

[0101] When viewed along the central axis CA, the second peripheral wall portion 99 has an outer peripheral surface that curves in an arc shape centered on the central axis CA, with a portion of the outer peripheral surface being teardrop-shaped and pointed outward, as shown in FIG. 18C . The pointed portion of the outer peripheral surface of the second peripheral wall portion 99 is a sharpened portion 99a, and the tip of the sharpened portion 99a is aligned with the direction indicated by the arrow AR1 formed on the top wall portion 95. The sharpened portion 99a also has a protrusion 99b that protrudes along the central axis CA from an end surface 99B of the second peripheral wall portion 99 (the opening of the mixer exterior body 23 into which the syringe 3 is inserted). Therefore, the protrusion 99b is formed at a position that coincides with the position of a recess 107A, one of the engagement portions 107, in the circumferential direction about the central axis CA.

[0102] The inner peripheral surface of the second peripheral wall portion 99 is formed with a step portion 98, a second step portion 98A, and an engaged portion 107 made up of three recesses 107A, 107B, and 107C.

[0103] The step portion 98 is formed at the boundary between the first peripheral wall portion 97 and the second peripheral wall portion 99, and is a stepped uneven portion that narrows the inner diameter of the mixer outer casing 23 toward the top wall portion 95. The step portion 98 extends in the circumferential direction (the rotation direction of the inner member IM), and when the static mixer 7 is attached to the tip of the syringe 3, the circular wall portion 41 a of the syringe 3 abuts against the step portion 98 (see FIG. 3 ).

[0104] The second step portion 98A is a stepped unevenness that narrows the inner diameter of the mixer exterior body 23 toward the top wall portion 95, and is formed at a position closer to an end surface 99B of the second peripheral wall portion 99 than the step portion 98. The second step portion 98A extends in the circumferential direction (the rotation direction of the inner member IM), and when the static mixer 7 is attached to the tip of the syringe 3, the second step portion 98A abuts against a step portion 49c formed on the outer peripheral surface of the paste storage chamber 49, 49' of the syringe 3 (see FIG. 3).

[0105] In addition, the engaged portion 107 forms an engagement structure that fixes the mounting member M to the tip portion of the syringe 3 (one end portion 41A of the syringe body 41), and is the part that engages with the engaging portion 45 (three protrusion pieces 45A, 45B, 45C) of the syringe 3.

[0106] The recesses 107A, 107B, and 107C have first grooves 107Aa, 107Ba, and 107Ca, respectively, and second grooves 107Ab, 107Bb, and 107Cb. Furthermore, windows 109A, 109B, and 109C are formed through the second peripheral wall 99 at positions corresponding to the second grooves 107Ab, 107Bb, and 107Cb, respectively. That is, the second grooves 107Ab, 107Bb, and 107Cb are formed by the edges of the windows 109A, 109B, and 109C. As shown in FIGS. 18D and 20 , the first grooves 107Aa, 107Ba, and 107Ca are formed by cutting out portions of the second step 98A and extend along the longitudinal direction X (center axis CA) to the step 98. The second grooves 107Ab, 107Bb, and 107Cb extend circumferentially from the closed ends (ends on the step portion 98 side) of the first grooves 107Aa, 107Ba, and 107Ca along the step portion 98. Furthermore, the bottom surfaces of the second grooves 107Ab, 107Bb, and 107Cb that face the step portion 98 are inclined so that the groove width in the longitudinal direction X gradually narrows from the first grooves 107Aa, 107Ba, and 107Ca side (see FIG. 19 ).

[0107] The recesses 107A, 107B, and 107C are aligned along the rotational direction of the mixer exterior body 23 and are asymmetrical about the central axis CA, which is the center of rotation of the mixer exterior body 23, when viewed along the central axis CA. The recesses 107A, 107B, and 107C are aligned at unequal intervals along the rotational direction of the mixer exterior body 23. That is, the recess 107A is formed on the inner circumferential surface of the second circumferential wall portion 99 at a position corresponding to a corner of the outer circumferential surface of the first circumferential wall portion 97 when viewed along the central axis CA. The recesses 107B and 107C are formed on the inner circumferential surface of the second circumferential wall portion 99 at positions corresponding to flat portions of the outer circumferential surface of the first circumferential wall portion 97 when viewed along the central axis CA (see FIGS. 18D and 21 ). Furthermore, recess 107A has a shape into which protrusion 45A, which is engaging portion 45, can be inserted, recess 107B has a shape into which protrusion 45B, which is engaging portion 45, can be inserted, and recess 107C has a shape into which protrusion 45C, which is engaging portion 45, can be inserted. Recesses 107A, 107B, and 107C have different shapes from one another when viewed along central axis CA.

[0108] The windows 109A, 109B, and 109C are formed with cutouts 109Aa, 109Ba, and 109Ca. The cutouts 109Aa, 109Ba, and 109Ca are formed at positions where the first grooves 107Aa, 107Ba, and 107Ca transition to the second grooves 107Ab, 107Bb, and 107Cb, respectively. This allows the protrusions 45A, 45B, and 45C that pass through the first grooves 107Aa, 107Ba, and 107Ca to be guided by the cutouts 109Aa, 109Ba, and 109Ca and smoothly enter the second grooves 107Ab, 107Bb, and 107Cb.

[0109] 18E , the second circumferential wall portion 99 also has an engaged portion 108 that engages with the engaging protrusion 46 of the syringe 3. The engaged portion 108 is formed on the outer periphery of the second circumferential wall portion 99 and has a recess 108A that extends in the circumferential direction of the second circumferential wall portion 99 (the rotational direction of the inner member IM) and an engaging window portion 108B that penetrates the recess 108A. The second circumferential wall portion 99 is thin at the portion where the recess 108A is formed. Therefore, when the inner circumferential surface of the portion where the recess 108A is formed is pressed from the inside, the second circumferential wall portion 99 is likely to bend radially outward.

[0110] As a result, when the mixer exterior body 23 is attached to the syringe 3, the engaging protrusions 46 press against the inner circumferential surface of the second circumferential wall portion 99, in which the recesses 108A are formed, slightly widening the second circumferential wall portion 99. When the mixer exterior body 23 is then rotated relative to the syringe 3, the engaging protrusions 46 move along the recesses 108A and fit into the engaging windows 108B. In other words, the engaging protrusions 46 and the engaging windows 108B form a rotation stopper for the mixer exterior body 23.

[0111] Furthermore, the mixer exterior body 23 is formed with a cylindrical wall portion 98B that rises from the edge of the second step portion 98A along the central axis CA and forms an opening of the mixer exterior body 23. The cylindrical wall portion 98B is a cylindrical wall surface that surrounds the periphery of the step portion 49c formed on the outer circumferential surface of the paste storage chamber 49, 49' when the static mixer 7 is attached to the tip of the syringe 3. As the cylindrical wall portion 98B rises from the edge of the second step portion 98A, the first groove portions 107Aa, 107Ba, 107Ca are each open inside the cylindrical wall portion 98B. In other words, the cylindrical wall portion 98B protrudes along the central axis CA beyond the engaged portion 107.

[0112] (Mixer biasing member) Figure 22A is a perspective view of the mixer biasing member 24, and Figure 22B is a bottom view. Also, Figure 23 is a cross-sectional view taken along line XXIII-XXIII shown in Figure 22B.

[0113] 3A, the mixer biasing member 24 is a plastic biasing member that is sandwiched between the mixer exterior body 23 (exterior body OM) and the mixer housing 21 (inner member IM). The mixer biasing member 24 is annular in shape surrounding a cylindrical passage (mixing passage 33) through which the paste passes, which is composed of an element housing portion 37 and an element group 39, and is plate-like in shape with a first surface 24A facing the mixer exterior body 23 and a second surface 24B facing the mixer housing 21.

[0114] The first surface 24A is formed with an exterior-body-side protrusion 24a that protrudes in the longitudinal direction X toward the mixer exterior body 23 and comes into contact with the inner surface of the mixer exterior body 23. In this embodiment, the exterior-body-side protrusion 24a includes an outer-circumferential protrusion 24a1 formed in an annular shape on the outer periphery of the first surface 24A of the mixer biasing member 24, and an inner-circumferential protrusion 24a2 formed in an annular shape on the inner periphery of the first surface 24A of the mixer biasing member 24.

[0115] Furthermore, on the second surface 24B, at a position different from the position where the exterior body side protrusion 24a is formed in the width direction Y perpendicular to the longitudinal direction X, an inner member side protrusion 24b is formed, which protrudes in the longitudinal direction X toward the mixer housing 21 and comes into contact with the mixer housing 21. In the present embodiment, the inner member side protrusion 24b includes an intermediate protrusion 24b1 formed in an annular shape between the outer periphery and the inner periphery of the second surface 24B.

[0116] [Cap] The cap 11 is fixed to the tip of the syringe 3 (one end 41A of the syringe body 41) in place of the static mixer 7 during storage or transportation of the paste injector 1. Components that are common to the static mixer 7 are given the same component names, and descriptions thereof may be omitted.

[0117] (Cap inner member) Fig. 24A is a perspective view of the cap inner member 25, Fig. 24B is a bottom view, and Fig. 25 is a cross-sectional view taken along line XXV-XXV shown in Fig. 24B.

[0118] The cap inner member 25 is a member that constitutes the inner member IM of the cap 11 that is the mounting member M, and is a member that corresponds to the mixing tip main body 19 and mixer housing 21 that are the inner member IM of the static mixer 7.

[0119] The cap inner member 25, like the mixing tip main body 19, includes a base 111, two insertion portions 113, 113', and a pair of rotational engagement pieces 115, 115'.

[0120] The base 111 is a cylindrical portion that fits inside the cap outer body 27, which is the outer body OM. A flange portion 117C that extends radially outward is formed on the outer periphery of the base 111. The flange portion 117C fits into a groove (circumferential groove 125) formed on the inner circumferential surface of the cap outer body 27, which will be described later, and the cap inner member 25 is fixed to the cap outer body 27 in a state that allows relative rotation about the central axis CA.

[0121] The two insertion portions 113, 113' and the pair of rotational engagement pieces 115, 115' are formed on a first end surface 111A of the base 111 that faces the syringe 3, and extend from the first end surface 111A in the longitudinal direction X. When the cap 11 is attached to the syringe 3, the two insertion portions 113, 113' are inserted into the two protrusions 43, 43' of the syringe 3, respectively. Unlike the case of the mixing tip main body 19, the insertion portions 113, 113' have a columnar shape (lid shape) for sealing the outlets 51, 51' of the syringe 3, and no passage is formed inside. The pair of rotational engagement pieces 115, 115' are portions that respectively engage with engagement grooves (a pair of first engagement grooves 127A, 127A' or a pair of second engagement grooves 127B, 127B') of the cap exterior body 27 described below.

[0122] A pair of first bottomed recesses 117A, 117A and a pair of second bottomed recesses 117B, 117B are formed on a second end face 111B opposite to the first end face 111A of the base 111. The pair of first bottomed recesses 117A, 117A and the pair of second bottomed recesses 117B, 117B are alternately formed in the circumferential direction when viewed along the central axis CA. Furthermore, a pair of second bottomed recesses 117B, 117B has a pair of through holes 117Bb, 117Bb formed in the bottoms thereof.

[0123] (Cap exterior body) Fig. 26A is a front view of cap exterior body 27, Fig. 26B is a side view, Fig. 26C is a plan view, Fig. 26D is a bottom view, and Fig. 26E is a perspective view. Also, Fig. 27 is a cross-sectional view taken along line XXVII-XXVII shown in Fig. 26C, Fig. 28 is a cross-sectional view taken along line XXVIII-XXVIII shown in Fig. 26C, and Fig. 29 is a cross-sectional view taken along line XXIX-XXIX shown in Fig. 26A.

[0124] The cap exterior body 27 is a cylindrical member that constitutes the exterior body OM of the cap 11, which is the mounting member M, and is a member that corresponds to the mixer exterior body 23, which is the exterior body OM of the static mixer 7. The cap 11, which is the mounting member M, is constituted by storing the cap inner member 25 and the cap biasing member 28 inside the cap exterior body 27. In addition, the cap exterior body 27 rotates relatively to the syringe 3 about the central axis CA.

[0125] The cap exterior body 27 includes a top wall portion 119 having a regular hexagonal outer periphery, a first peripheral wall portion 121 rising from the edge of the top wall portion 119, and a second peripheral wall portion 123 extending continuously from the first peripheral wall portion 121 via a step. The interior of the cap exterior body 27 defines a first space S1 surrounded by the top wall portion 119 and the first peripheral wall portion 121, and a second space S2 surrounded by the second peripheral wall portion 123 (see FIGS. 25 and 26 ). An inner member IM and a cap biasing member 28, which are formed as the cap inner member 25, fit into the first space S1 in a rotatable manner about a central axis CA. The tip end of the syringe 3 (one end 41A of the syringe body 41) is inserted into the second space S2 with the inner member IM housed therein.

[0126] The top wall 119 is a portion that closes the first space S1. Unlike the mixing tip main body 19, the top wall 119 is made of a curved plate member and does not have a top through-cylinder formed in the center. In addition, an arrow AR1 indicating the position of a recess 129A (described later) is engraved on the surface of the top wall 119 (see FIG. 26C).

[0127] When viewed along the central axis CA, the outer peripheral surface of the first circumferential wall portion 121 has a regular hexagonal shape as shown in Fig. 26C. When viewed along the central axis CA, the inner peripheral surface of the first circumferential wall portion 121 has a circular shape as shown in Fig. 26D. The inner peripheral surface of the first circumferential wall portion 121 is formed with a circumferential groove 125, a pair of first engaged grooves 127A, 127A', and a pair of second engaged grooves 127B, 127B'.

[0128] The circumferential groove 125 is a recess into which the flange portion 117C of the cap inner member 25 fits, and extends in the circumferential direction (the rotation direction of the cap inner member 25).

[0129] The first engaged groove 127A and the second engaged groove 127B on one side are recesses with which one of the rotary engaging pieces 115 engages. The first engaged groove 127A' and the second engaged groove 127B' on the other side are recesses with which the other of the rotary engaging pieces 115' engages. The pair of first engaged grooves 127A, 127A' and the pair of second engaged grooves 127B, 127B' are arranged side by side in the circumferential direction (the rotational direction of the cap inner member 25) at a predetermined interval. Here, the pair of first engaged grooves 127A, 127A' are formed at positions facing each other in the thickness direction Z across the central axis CA. The pair of second engaged grooves 127B, 127B' are formed at positions facing each other in a direction offset in the circumferential direction from the thickness direction Z across the central axis CA.

[0130] When assembled into the cap 11, the cap inner member 25 rotates relative to the cap outer body 27 about the central axis CA. At this time, one rotational engagement piece 115 engages with either the first engaged groove 127A or the second engaged groove 127B, and the other rotational engagement piece 115' engages with either the first engaged groove 127A' or the second engaged groove 127B', depending on the positional relationship in the rotational direction between the cap inner member 25 and the cap outer body 27. This determines the relative rotational positions of the cap inner member 25 and the cap outer body 27.

[0131] When viewed along the central axis CA, the second circumferential wall portion 123 has an outer peripheral surface that curves in an arc shape centered on the central axis CA, with a portion of the outer peripheral surface being teardrop-shaped and pointed outward, as shown in FIG. 26C . The pointed portion of the outer peripheral surface of the second circumferential wall portion 123 is a sharpened portion 123a, and the tip of the sharpened portion 123a is aligned with the direction indicated by the arrow AR1 formed on the top wall portion 119. Furthermore, the sharpened portion 123a is formed with a protrusion 123b that protrudes along the central axis CA from an end surface 123B of the second circumferential wall portion 123 (the opening of the cap exterior body 27 into which the syringe 3 is inserted). Therefore, the protrusion 123b is formed at a position that coincides with the position of the recess 129A, one of the engagement portions 129, in the circumferential direction centered on the central axis CA.

[0132] The inner peripheral surface of the second peripheral wall portion 123 is formed with a step portion 120, a second step portion 120A, and an engaged portion 129 made up of three recesses 129A, 129B, and 129C.

[0133] Step portion 120 is formed at the boundary between first peripheral wall portion 121 and second peripheral wall portion 123, and is a stepped unevenness that narrows the inner diameter of cap exterior body 27 toward top wall portion 119. Step portion 120 extends in the circumferential direction (the rotation direction of inner member IM), and when cap 11 is attached to the tip of syringe 3, circular wall portion 41 a of syringe 3 abuts against step portion 120.

[0134] The second step portion 120A is a stepped unevenness that narrows the inner diameter of the cap exterior body 27 toward the top wall portion 119, and is formed at a position closer to an end surface 123B of the second peripheral wall portion 123 than the step portion 120. The second step portion 120A extends in the circumferential direction (the rotation direction of the inner member IM), and when the cap 11 is attached to the tip of the syringe 3, the second step portion 120A abuts against a step portion 49c formed on the outer peripheral surface of the paste storage chamber 49, 49' of the syringe 3.

[0135] In addition, the engaged portion 129 forms an engagement structure that fixes the mounting member M to the tip portion of the syringe 3 (one end portion 41A of the syringe body 41), and is the part that engages with the engagement portion 45 (three protrusion pieces 45A, 45B, 45C) of the syringe 3.

[0136] The recesses 129A, 129B, and 129C have first grooves 129Aa, 129Ba, and 129Ca, and second grooves 129Ab, 129Bb, and 129Cb, respectively. Window portions 131A, 131B, and 131C are formed through the second peripheral wall portion 123 at positions corresponding to the second grooves 129Ab, 129Bb, and 129Cb, respectively. In other words, the second grooves 129Ab, 129Bb, and 129Cb are defined by the edges of the window portions 131A, 131B, and 131C. 26D, 28, etc., the first grooves 129Aa, 129Ba, 129Ca are formed by cutting out a portion of the second step portion 120A and extend along the longitudinal direction X (central axis CA) to the step portion 120. The second grooves 129Ab, 129Bb, 129Cb extend circumferentially along the step portion 120 from the closed ends (the ends on the step portion 120 side) of the first grooves 129Aa, 129Ba, 129Ca. Furthermore, the bottom surfaces of the second grooves 129Ab, 129Bb, 129Cb facing the step portion 120 are inclined so that the groove width in the longitudinal direction X gradually narrows from the first grooves 129Aa, 129Ba, 129Ca side (see FIG. 27).

[0137] The recesses 129A, 129B, and 129C are aligned along the rotational direction of the cap exterior body 27 and are asymmetrical about the central axis CA, which is the center of rotation of the cap exterior body 27, when viewed along the central axis CA. The recesses 129A, 129B, and 129C are aligned at unequal intervals along the rotational direction of the cap exterior body 27. That is, the recess 129A is formed on the inner circumferential surface of the second circumferential wall portion 123 at a position corresponding to a corner of the outer circumferential surface of the first circumferential wall portion 121 when viewed along the central axis CA. The recesses 129B and 129C are formed on the inner circumferential surface of the second circumferential wall portion 123 at positions corresponding to flat portions of the outer circumferential surface of the first circumferential wall portion 121 when viewed along the central axis CA (see FIGS. 24D and 27 ). Furthermore, recess 129A has a shape into which protrusion 45A, which is engaging portion 45, can be inserted, recess 129B has a shape into which protrusion 45B, which is engaging portion 45, can be inserted, and recess 129C has a shape into which protrusion 45C, which is engaging portion 45, can be inserted. Recesses 129A, 129B, and 129C have different shapes when viewed along central axis CA.

[0138] The windows 131A, 131B, and 131C are formed with cutouts 131Aa, 131Ba, and 131Ca. The cutouts 131Aa, 131Ba, and 131Ca are formed at positions where the first grooves 129Aa, 129Ba, and 129Ca transition to the second grooves 129Ab, 129Bb, and 129Cb, respectively. This allows the protrusions 45A, 45B, and 45C that pass through the first grooves 129Aa, 129Ba, and 129Ca to be guided by the cutouts 131Aa, 131Ba, and 131Ca and smoothly enter the second grooves 129Ab, 129Bb, and 129Cb.

[0139] 26E , the second circumferential wall portion 123 also has an engaged portion 130 that engages with the engaging protrusion 46 of the syringe 3. The engaged portion 130 is formed on the outer periphery of the second circumferential wall portion 123 and has a recess 130A that extends in the circumferential direction of the second circumferential wall portion 123 (the rotational direction of the inner member IM) and an engaging window portion 130B that penetrates the recess 130A. The second circumferential wall portion 123 is thin at the portion where the recess 130A is formed. Therefore, when the inner circumferential surface of the portion where the recess 130A is formed is pressed from the inside, the second circumferential wall portion 123 is likely to bend radially outward.

[0140] As a result, when cap exterior body 27 is attached to syringe 3, engaging protrusion 46 presses against the inner circumferential surface of second circumferential wall portion 123, in which recess 130A is formed, slightly widening second circumferential wall portion 123. When cap exterior body 27 is then rotated relative to syringe 3, engaging protrusion 46 moves along recess 130A and fits into engaging window portion 130B. In other words, engaging protrusion 46 and engaging window portion 130B form a rotation stopper for cap exterior body 27.

[0141] Furthermore, the cap exterior body 27 is formed with a cylindrical wall portion 120B that rises from the edge of the second step portion 120A along the central axis CA and forms an opening of the cap exterior body 27. The cylindrical wall portion 120B is a cylindrical wall surface that surrounds the periphery of the step portion 49c formed on the outer peripheral surface of the paste storage chamber 49, 49' when the cap 11 is attached to the tip of the syringe 3. As the cylindrical wall portion 120B rises from the edge of the second step portion 120A, the first groove portions 129Aa, 129Ba, 129Ca are each open inside the cylindrical wall portion 120B. In other words, the cylindrical wall portion 120B protrudes along the central axis CA beyond the engaged portion 129.

[0142] (Cap biasing member) Figure 30A is a perspective view of the cap biasing member 28, and Figure 30B is a bottom view thereof. Also, Figure 31 is a cross-sectional view taken along line XXXI-XXXI shown in Figure 30B.

[0143] 3B , the cap biasing member 28 is a plastic biasing member sandwiched between the cap exterior body 27 (exterior body OM) and the cap inner member 25 (inner member IM). The cap biasing member 28 has an annular plate shape having a first surface 28A facing the cap exterior body 27 and a second surface 28B facing the cap inner member 25.

[0144] The first surface 28A is formed with an exterior body side protrusion 28a that protrudes in the longitudinal direction X toward the cap exterior body 27 and comes into contact with the inner surface of the cap exterior body 27. In the present embodiment, the exterior body side protrusion 28a includes an outer peripheral side protrusion 28a1 that is formed in an annular shape on the outer periphery of the first surface 28A of the cap biasing member 28, and an inner peripheral side protrusion 28a2 that is formed in an annular shape on the inner periphery of the first surface 28A of the cap biasing member 28.

[0145] Further, on the second surface 28B, at a position different from the position where the exterior body side protrusion 28a is formed in the width direction Y perpendicular to the longitudinal direction X, an inner member side protrusion 28b is formed, which protrudes in the longitudinal direction X toward the cap inner member 25 and comes into contact with the cap inner member 25. In the present embodiment, the inner member side protrusion 28b includes an intermediate protrusion 28b1 formed in an annular shape between the outer circumferential portion and the inner circumferential portion of the second surface 28B.

[0146] [Details of the process up to securing the mounting member] Using Figures 32, 33, and 34A to 34C, details of the process up to securing the mounting member M to the syringe 3 will be described using the static mixer 7 as an example. Figure 32 is a diagram showing the state prior to the static mixer 7 being placed over and secured to the syringe 3. In Figure 32, the bottom surface of the static mixer 7 is shown, and the syringe 3 is shown in plan view with the finger grip 47 omitted. Also, in Figures 32 and 33, the inner member IM is shown colored gray. Figures 34A to 34C are diagrams showing the process up to securing the static mixer 7 to the tip of the syringe 3. Figure 34A is a cross-sectional view of the static mixer 7 before the tip of the syringe 3 is inserted into the static mixer 7, Figure 34B is a cross-sectional view of the static mixer 7 and the syringe 3 while the tip of the syringe 3 is being inserted into the static mixer 7, and Figure 34C is a cross-sectional view of the static mixer 7 and the syringe 3 with the static mixer 7 fixed to the tip of the syringe 3.

[0147] 32 , before being fixed to the syringe 3, the static mixer 7 is in a state in which one rotary engagement piece 91 is engaged with one second engaged groove 105B, and the other rotary engagement piece 91' is engaged with the other second engaged groove 105B'. In other words, the width direction Y of the mixer exterior body 23 does not coincide with the width direction Y of the inner member IM. In this state, the circular wall portion 41a of the syringe 3 can be inserted into the second space S2 surrounded by the second peripheral wall portion 99 of the mixer exterior body 23 only when the first groove portions 107Aa, 107Ba, and 107Ca of the recesses 107A, 107B, and 107C are positioned opposite the three protrusion pieces 45A, 45B, and 45C of the syringe 3, respectively. Only at this time does the protruding portion 43 of the syringe 3 face the insertion portion 89 of the mixing chip body 19 , and the protruding portion 43 ′ of the syringe 3 face the insertion portion 89 ′ of the mixing chip body 19 .

[0148] The user can align protrusion 45A with recess 107A by aligning arrow AR1 on the surface of top wall 95 with protrusion 45A. As a result, first groove 107Aa of recess 107A faces protrusion 45A, first groove 107Ba of recess 107B faces protrusion 45B, first groove 107Ca of recess 107C faces protrusion 45C, insertion portion 89 faces protrusion 43, and insertion portion 89' faces protrusion 43'.

[0149] Furthermore, in this embodiment, the opening of the mixer exterior body 23 is formed with a second step portion 98A and a cylindrical wall portion 98B, which can be used to align the protrusion 45 with the engaged portion 107. That is, if the circular wall portion 41a of the syringe 3 is inserted into the mixer exterior body 23 without aligning the protrusion 45 with the engaged portion 107, the circular wall portion 41a of the syringe 3 comes into contact with the second step portion 98A and the cylindrical wall portion 98B and does not enter the second space S2. This allows the central axis CA of the mixer exterior body 23 and the central axis CA of the syringe 3 to be aligned, thereby enabling engagement between the engaging portion 45 (engaged portion 107) while suppressing misalignment between them. In this state, the mixer outer casing 23 can be rotated relative to the syringe 3 around the central axis CA to find the position where the circular wall portion 41a of the syringe 3 enters the second space S2 (i.e., the position where the protrusion piece 45A and the recess 107A, the protrusion piece 45B and the recess 107B, and the protrusion piece 45C and the recess 107C are aligned).

[0150] Furthermore, as shown in FIG. 34A, when not attached to the syringe 3, the mixer biasing member 24 is simply contained within the space between the mixer exterior body 23 and the mixer housing 21, and is not compressed by the mixer exterior body 23 and the mixer housing 21.

[0151] When the circular wall portion 41a of the syringe 3 is inserted into the second space S2, the insertion portion 89 is inserted into the protrusion 43, and the insertion portion 89' is inserted into the protrusion 43'. As a result, the rotational position of the inner member IM (the mixing tip main body 19 and the mixer housing 21) is fixed relative to the syringe 3. The protrusion 45A is inserted into the first groove 107Aa of the recess 107A and abuts against the step 98. The protrusion 45B is inserted into the first groove 107Ba of the recess 107B and abuts against the step 98. The protrusion 45C is inserted into the first groove 107Ca of the recess 107C and abuts against the step 98.

[0152] As shown in FIG. 34B, when the syringe 3 is simply inserted into the static mixer 7, there is play (gap) between the syringe 3 and the mixer housing 21, and the mixer biasing member 24 is not compressed.

[0153] When the mixer exterior body 23 rotates about the central axis CA with the syringe 3 inserted in the static mixer 7, the inner member IM (the mixing tip main body 19 and the mixer housing 21) does not rotate, and only the mixer exterior body 23, which is the exterior body OM, rotates. As a result, the static mixer 7 is in the state shown in Figures 33 and 34C.

[0154] FIG. 33 is a bottom view of the static mixer 7 after only the mixer exterior body 23 has rotated (the inserted syringe 3 is not shown). When only the mixer exterior body 23 rotates, one rotational engagement piece 91 engages with one of the first engagement grooves 105A, and the other rotational engagement piece 91' engages with the other first engagement groove 105A'. Furthermore, the protrusion 45A moves from the end of the first groove 107Aa along the step 98 into the second groove 107Ab and is exposed to the outside through the window 109A. Furthermore, the protrusion 45B moves from the end of the first groove 107Ba along the step 98 into the second groove 107Bb and is exposed to the outside through the window 109B. Furthermore, the protrusion 45C moves from the end of the first groove 107Ca along the step 98 into the second groove 107Cb and is exposed to the outside through the window 109C. As a result, the protruding pieces 45A, 45B, and 45C are engaged with the recesses 107A, 107B, and 107C, respectively, and the static mixer 7 and the syringe 3 are fixed to each other.

[0155] Furthermore, because the groove widths of the second grooves 107Ab, 107Bb, and 107Cb in the longitudinal direction X gradually narrow from the first grooves 107Aa, 107Ba, and 107Ca side, the protrusions 45A, 45B, and 45C gradually approach the step portion 98 as the mixer exterior body 23 rotates. As a result, the syringe 3 gradually presses the inner member IM (the mixing tip main body 19 and the mixer housing 21), and the mixer exterior body 23 and the mixer housing 21 move relatively closer to each other. As a result, the mixer biasing member 24 is gradually compressed between the mixer exterior body 23 and the mixer housing 21, and gradually bends.

[0156] That is, as the syringe 3 and the mixer exterior body 23 rotate relative to each other, the syringe 3 is pushed into the static mixer 7 simultaneously with this relative rotation, causing the syringe 3 to interfere with the mixing tip main body 19, and the mixing tip main body 19 and the mixer housing 21 to move relatively closer to the mixer exterior body 23. As a result, a force toward the mixer housing 21 acts on the exterior body-side protrusions 24a (outer peripheral protrusions 24a1 and inner peripheral protrusions 24a2) of the mixer biasing member 24 disposed between the mixer housing 21 and the mixer exterior body 23, and a force toward the mixer exterior body 23 acts on the inner member-side protrusions 24b (middle protrusions 24b1) that are in contact with the mixer housing 21. The mixer biasing member 24 then bends in a convex curve toward the mixer exterior body 23 around the inner member-side protrusions 24b. As a result, the mixer biasing member 24 biases the mixing tip main body 19 and the mixer housing 21 (inner member IM) against the syringe 3.

[0157] 34C , in this state, the mixer biasing member 24 is held in a compressed state between the mixer exterior body 23 and the mixer housing 21. As a result, the outlets 51, 51' of the syringe 3 and the boundary portions around the insertion portions 89, 89' of the static mixer 7 (mounting member M) (in this embodiment, particularly the boundary portion BL between the protrusions 43, 43' and the flange portion 117C) are in tight contact. Therefore, even if the length of the insertion portions 89, 89' is shortened, leakage of paste from between the syringe 3 and the static mixer 7 can be prevented.

[0158] If the biasing force of the mixer biasing member 24 is too strong, it becomes difficult to rotate the mixer exterior body 23 about the central axis CA and fix the static mixer 7 and the syringe 3 to each other. On the other hand, if the biasing force of the mixer biasing member 24 is too weak, there is a risk of paste leaking at the boundary portion. Therefore, the biasing force of the mixer biasing member 24 should be such that it is easy to rotate the mixer exterior body 23 and can prevent paste from leaking at the boundary portion.

[0159] <Function of Paste Injector> The function of the paste injector will be described below.

[0160] The paste injector 1 of this embodiment includes a syringe 3 extending in the longitudinal direction X, having paste storage chambers 49, 49' extending along the longitudinal direction X and filled with paste, and having outlets 51, 51' formed at one end thereof to open one end of the paste storage chambers 49, 49', an outer casing OM fixed to one end of the syringe 3 via an engagement structure (an engaging portion 45 and an engaged portion 107, or an engaging portion 45 and an engaged portion 129), and an outer casing OM. The syringe 3 includes an attachment member M having an inner member IM provided inside the outer casing OM and having an insertion portion (89, 89' or 113, 113') formed thereon to be inserted into the outlet 51, 51' of the syringe 3, and a biasing member EM sandwiched between the outer casing OM and the inner member IM, and when the attachment member M is fixed to one end of the syringe 3, the biasing member EM is compressed between the outer casing OM and the inner member IM to bias the inner member IM against the syringe 3.

[0161] By providing the biasing member EM in this manner, when the mounting member M is fixed to one end of the syringe 3, the biasing member EM is compressed between the outer casing OM and the inner member IM, biasing the inner member IM against the syringe 3. As a result, the boundary portion around the outlet 51, 51' of the syringe 3 and the insertion portion (89, 89' or 113, 113') of the mounting member M is tightly fitted. Therefore, regardless of the length of the insertion portion, leakage of paste from between the syringe 3 and the mounting member M can be prevented.

[0162] The mounting member M may be, for example, a static mixer 7 that mixes and discharges paste, or a cap 11 that seals the discharge ports 51, 51' of the syringe 3. When the mounting member M is a static mixer 7, shortening the length of the insertion portions (89, 89') reduces the amount of pre-mixed paste remaining in the insertion portions (89, 89') (paste passages 29, 29'), thereby suppressing paste loss.

[0163] The biasing member EM is plate-shaped and has a first surface (24A or 28A) facing the outer body OM and a second surface (24B or 28B) facing the inner member IM, and the first surface is formed with an outer body side protrusion (24a or 28a) that protrudes in the longitudinal direction X toward the outer body OM and comes into contact with the inner surface of the outer body OM, and the second surface may be formed with an inner member side protrusion (24b or 28b) that protrudes in the longitudinal direction X toward the inner member IM and comes into contact with the inner member IM at a position different from the position where the outer body side protrusion is formed in the width direction Y perpendicular to the longitudinal direction X.

[0164] When such a biasing member EM is used, when the mounting member M is fixed to one end of the syringe 3, the exterior body OM and the exterior body-side protrusion come into contact, and the inner member IM and the inner member-side protrusion come into contact, the exterior body OM presses the exterior body-side protrusion, and force is transmitted to the inner member-side protrusion. At this time, force is applied to the exterior body-side protrusion and the inner member-side protrusion, which are positioned offset in the width direction, causing the biasing member EM, which is a plate material, to bend and bias the inner member against the syringe.

[0165] When the mounting member M has a cylindrical passage (mixing passage 33) through which the paste passes and the biasing member EM is an annular plate surrounding the passage, the exterior body protrusion (24a or 28a) may include an outer peripheral protrusion (24a1 or 28a1) formed in an annular shape on the outer periphery of the first surface of the biasing member EM and an inner peripheral protrusion (24a2 or 28a2) formed in an annular shape on the inner peripheral part of the first surface of the biasing member EM, and the inner member protrusion (24b or 28b) may include an intermediate protrusion (24b1 or 28b1) formed in an annular shape between the outer peripheral part and the inner peripheral part of the second surface. If the exterior body protrusion and the inner member protrusion are configured in this manner, the exterior body OM presses the outer peripheral protrusion and the inner peripheral protrusion, and force is transmitted to the mixer housing 21 via the intermediate protrusion. At this time, the biasing member EM, which is a plate material, bends in a convex shape toward the exterior body OM around the inner member protrusion, biasing the inner member against the syringe. Because the exterior body protrusion and the inner member protrusion are annular and extend continuously in the circumferential direction around the central axis, the biasing member can uniformly bias the inner member against the syringe along the central axis.

[0166] The biasing member EM may be an elastic body that is compressed between the outer casing OM and the inner member IM and biases the inner member IM against the syringe 3. It goes without saying that, for example, a spring, rubber, sponge, or the like may be used. To bias the inner member IM against the syringe 3 using an elastic body such as rubber or sponge, a certain volume is required in terms of the elastic force of the elastic body. In other words, when using rubber, sponge, or the like as the biasing member EM, a relatively large volume is required to ensure the necessary biasing force. On the other hand, using a spring as the biasing member EM makes it easier to adjust the biasing effect. For this reason, a spring is preferably used as the biasing member EM. Examples of springs include coil springs and annular springs (i.e., disc springs). When an annular spring (disc spring) surrounding the passage is used as the biasing member EM, an annular spring is preferred because it allows for a smaller outer casing OM. Furthermore, the material of the biasing member EM is not particularly limited, but examples include metal and resin. Resins include plastic materials and elastomer materials. Examples of plastic materials include thermoplastic resins such as polystyrene, polypropylene, polyacetal, and polyether ketone; thermosetting resins such as melamine resin, polyester resin, and phenolic resin; and foam plastics such as polyurethane foam and polystyrene foam. Examples of elastomer materials include rubbers such as urethane rubber, silicone rubber, and fluororubber; and thermoplastic elastomers such as styrene-based elastomers. Resin is preferable to metal as the material for the biasing member EM because of its lightweight, low-cost mass production by injection molding, ease of disposal after use, and resistance to breakage and wear when surrounding components are made of resin. Furthermore, among resins, plastic materials are more preferable because they can improve the durability of the biasing effect. Among plastic materials, thermoplastic resins are even more preferable, and polyacetal is the most preferable.

[0167] When the exterior body OM and the inner member IM are relatively rotatable about the central axis CA of the syringe 3 extending in the longitudinal direction X, the engagement structure includes a plurality of engagement portions (projections 45A, 45B, 45C) that protrude from the outer circumferential surface of the syringe 3 and are arranged in a circumferential direction around the central axis CA, and first groove portions (107Aa, 107Ba, The groove portion may be composed of a first groove portion (107Ca, or 129Aa, 129Ba, 129Ca) and a second groove portion (107Ab, 107Bb, 107Cb, or 129Ab, 129Bb, 129C) extending circumferentially continuously from the other end of the first groove portion, and may have a plurality of engaged portions (indentations 107A, 107B, 107C, or 129A, 129B, 129C) into which the plurality of engaging portions can be inserted, respectively.

[0168] When the engagement structure is configured in this manner, the engaging portion is inserted into the first groove of the engaged portion, and then the syringe is rotated around the central axis of the syringe relative to the mounting member, engaging the engaging portion with the second groove and securing the exterior body to the syringe. This configuration makes it easy to attach and detach the mounting member.

[0169] The engagement structure may be any structure capable of fastening the exterior body to the syringe, and may, for example, be a snap-in structure in which one end of the syringe is pushed into the exterior body to engage with it.

[0170] In a method for mixing dental materials using the paste injector 1 of this embodiment, first, the plunger 5 is inserted into the paste storage chambers 49, 49' that have dental paste pre-filled therein. This causes the dental paste to be extruded from each paste storage chamber 49, 49' through the paste passages 29, 29' and into the intermediate passage 31. The dental paste then flows from the intermediate passage 33 into the mixing passage 33, and as it passes through the mixing passage 33, it is stirred and mixed by the element group 39 and prepared as a dental material.

[0171] Here, the paste injector 1 of this embodiment can prevent leakage of paste from between the syringe 3 and the static mixer 7, regardless of the length of the insertion portions 89, 89' of the static mixer 7, which is the mounting member M. Therefore, in the method for mixing dental materials using the paste injector 1 of this embodiment, multiple dental pastes can be mixed appropriately from the viewpoint of preventing leakage of the paste.

[0172] Although the embodiment of the present invention has been specifically described above, the present invention is not limited to this embodiment, and it goes without saying that modifications are possible within the scope of the technical concept of the present invention.

[0173] For example, in the above example, the biasing members (mixer biasing member and cap biasing member) used had outer and inner peripheral protrusions as the exterior body protrusions and an intermediate protrusion as the inner member protrusion, but, for example, the exterior body protrusions may only have outer peripheral protrusions or only inner peripheral protrusions. Also, in the above example, the exterior body protrusions and the inner member protrusions were annular, but they may be formed, for example, with protrusions arranged randomly on the first surface or the second surface, or with protrusions arranged intermittently.

[0174] In addition to the above-described embodiments, the following is further disclosed: (1) A paste injector comprising: a syringe extending in a longitudinal direction, having a paste storage chamber extending along the longitudinal direction therein and filled with paste, and having an outlet formed at one end thereof that opens one end of the paste storage chamber; an exterior body fixed to the one end of the syringe via an engaging structure; an inner member provided inside the exterior body and having an insertion portion formed therein to be inserted into the outlet of the syringe; and an attachment member having a biasing member sandwiched between the exterior body and the inner member, wherein the biasing member is compressed between the exterior body and the inner member when the attachment member is fixed to the one end of the syringe, and biases the inner member against the syringe. (2) The paste injector described in (1) is characterized in that the urging member is plate-shaped and has a first surface facing the outer body and a second surface facing the inner member, and the first surface has an outer body side protrusion formed thereon that protrudes toward the outer body in the longitudinal direction and contacts the inner surface of the outer body, and the second surface has an inner member side protrusion formed thereon that protrudes toward the inner member in the longitudinal direction and contacts the inner member at a position different from the position at which the outer body side protrusion is formed in the width direction perpendicular to the longitudinal direction. (3) The paste injector according to (2), characterized in that the mounting member has a cylindrical passage through which the paste passes, the biasing member is an annular plate surrounding the passage, the outer body side protrusion includes an outer peripheral side protrusion formed in an annular shape on the outer periphery of the first surface of the biasing member and an inner peripheral side protrusion formed in an annular shape on the inner periphery of the first surface of the biasing member, and the inner member side protrusion includes an intermediate protrusion formed in an annular shape between the outer peripheral part and the inner peripheral part of the second surface.(4) The paste injector according to any one of (1) to (3), wherein the exterior body and the inner member are relatively rotatable around a central axis of the syringe extending in the longitudinal direction, and the engagement structure comprises: a plurality of engagement portions protruding from the outer circumferential surface of the syringe and arranged side by side in a circumferential direction around the central axis; a first groove portion formed on the inner surface of the exterior body, extending in the longitudinal direction, with one end open toward the syringe, and a second groove portion extending circumferentially continuously from the other end of the first groove, and wherein the plurality of engagement portions have a plurality of engageable portions into which they can be inserted. (5) The paste injector according to any one of (1) to (4), wherein the attachment member is a static mixer that mixes and discharges the paste. (6) The paste injector according to any one of (1) to (4), wherein the attachment member is a cap that seals the discharge port of the syringe. (7) A method for mixing dental materials using the paste injector according to any one of (1) to (6). CROSS-REFERENCE TO RELATED APPLICATIONS

[0175] This application claims priority based on Japanese Patent Application No. 2024-012736, filed with the Japan Patent Office on January 31, 2024, the entire disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A paste injector comprising: a syringe extending in a longitudinal direction, having a paste storage chamber extending longitudinally therein and filled with paste, with one end formed with a discharge port that opens one end of the paste storage chamber; an exterior body fixed to the one end of the syringe via an engaging structure; an inner member provided inside the exterior body and formed with an insertion portion that is inserted into the discharge port of the syringe; and an attachment member having a biasing member sandwiched between the exterior body and the inner member, wherein the biasing member is compressed between the exterior body and the inner member when the attachment member is fixed to the one end of the syringe, and biases the inner member against the syringe.

2. The paste injector of claim 1, characterized in that the biasing member is plate-shaped and has a first surface facing the outer body and a second surface facing the inner member, the first surface having an outer body-side protrusion that protrudes in the longitudinal direction toward the outer body and comes into contact with the inner surface of the outer body, and the second surface has an inner member-side protrusion that protrudes in the longitudinal direction toward the inner member and comes into contact with the inner member, at a position different from the position at which the outer body-side protrusion is formed in the width direction perpendicular to the longitudinal direction.

3. The paste injector according to claim 2, characterized in that: the mounting member has a cylindrical passage through which the paste passes; the biasing member is an annular plate surrounding the passage; the outer body side protrusion includes an outer peripheral side protrusion formed in an annular shape on the outer periphery of the first surface of the biasing member, and an inner peripheral side protrusion formed in an annular shape on the inner periphery of the first surface of the biasing member; and the inner member side protrusion includes an intermediate protrusion formed in an annular shape between the outer peripheral part and the inner peripheral part of the second surface.

4. A paste injector as described in claim 1 or claim 2, characterized in that the outer casing and the inner member are rotatable relative to each other around the central axis of the syringe extending in the longitudinal direction, and the engagement structure comprises a plurality of engagement portions that protrude from the outer circumferential surface of the syringe and are arranged in a circumferential direction around the central axis, a first groove portion that is formed on the inner surface of the outer casing and extends in the longitudinal direction, with one end open toward the syringe, and a second groove portion that extends circumferentially continuously from the other end of the first groove portion, and each of the plurality of engagement portions has a plurality of engageable portions into which it can be inserted.

5. A paste injector according to claim 1 or 2, characterized in that the mounting member is a static mixer that mixes and discharges the paste.

6. A paste injector according to claim 1 or 2, characterized in that the mounting member is a cap that seals the outlet of the syringe.

7. A method for mixing dental materials using the paste injector according to any one of claims 1 to 6.

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