Protective cap

Abstract

To realize a protective cap having novel structure different from conventional protective caps.SOLUTION: In a cap body (1) of a protective cap (10), a cylindrical portion (2) having an approximately rectangular cylindrical shape has an outer rib (5) extending downward from an inner ceiling surface (3a) of a cap portion (3) on an outer peripheral surface (2b) of a corner portion (21) connecting side walls (22), and an inner rib (4) extending downward from the inner ceiling surface (3a) of the cap portion (3) on an inner peripheral surface (2a) of the side wall (22).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a protective cap. [Background technology]

[0002] Resin protective caps that are attached to the ends of iron pipes or reinforcing bars to protect the exposed ends of reinforcing bars or pipes at construction sites, etc. Such protective caps are disclosed, for example, in Utility Model Document 1 and Patent Document 2.

[0003] On the other hand, in recent years, from the viewpoint of environmental considerations during and after the disposal of resin products, there has been active development of biodegradable resins (hereinafter sometimes referred to as "biodegradable resins"). One type of such biodegradable resin is known as polyhydroxyalkanoic acid (hereinafter referred to as PHA). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Utility Model Registration No. 3013107 [Patent Document 2] Japanese Patent Application Publication No. 09-291705 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in addition to the conventional protective caps described above, there has been a demand for protective caps with new shapes.

[0006] Therefore, an object of one aspect of the present invention is to realize a protective cap having a novel structure different from conventional protective caps. [Means for solving the problem]

[0007] In order to solve the above problems, a protective cap according to one embodiment of the present invention comprises a cap body having a tubular portion of approximately rectangular cylindrical shape that is attached to at least one of reinforcing bars and pipes, and a cap portion formed integrally with the tubular portion at the upper end of the tubular portion, and in the cap body, the tubular portion is characterized in that it has an outer rib extending downward from the inner ceiling surface of the cap portion on the outer surface of the corner that connects the approximately rectangular tubular side walls, and an inner rib extending downward from the inner ceiling surface of the cap portion on the inner surface of the approximately rectangular tubular side wall. [Effects of the Invention]

[0008] According to one aspect of the present invention, a protective cap having a novel structure different from conventional protective caps can be realized. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows the configuration of a protective cap according to a first embodiment of the present invention, in which 101 is a perspective view seen from the side and 102 is a perspective view seen from below. [Figure 2] 1 is a bottom view showing the configuration of a protection cap according to a first embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view taken along the line AA shown in FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view taken along the line BB shown in FIG. 2. [Figure 5] 1 is a side view showing the configuration of a protection cap according to a first embodiment of the present invention. [Figure 6] FIG. 10 is a perspective view seen from the side, showing the configuration of a protective cap according to a second embodiment of the present invention. [Figure 7] FIG. 10 is a bottom view showing the configuration of a protection cap according to a second embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view taken along the line AA shown in FIG. [Figure 9] FIG. 8 is a cross-sectional view taken along the line BB shown in FIG. [Figure 10] FIG. 10 is a side view showing the configuration of a protection cap according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will be described in detail below. In this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more and B or less." In addition, all documents described in this specification are incorporated herein by reference.

[0011] [Embodiment 1] A first embodiment of the present invention will be described in detail below. Fig. 1 shows the configuration of a protective cap 10 according to this embodiment, with 101 in Fig. 1 being a perspective view seen from the side and 102 in Fig. 1 being a perspective view seen from below. Fig. 2 is a bottom view showing the configuration of the protective cap 10 according to this embodiment. Fig. 3 is a cross-sectional view taken along line AA shown in Fig. 2. Fig. 4 is a cross-sectional view taken along line BB shown in Fig. 2. Fig. 5 is a side view showing the configuration of the protective cap 10 according to this embodiment.

[0012] As shown in the drawings, in this specification, the direction of the central axis X of the protective cap 10 is referred to as the HD direction, and one side (upper side) in the HD direction is referred to as the HDa side, and the other side (lower side) in the HD direction is referred to as the HDb side. The circumferential direction of the protective cap 10 perpendicular to the HD direction is referred to as the RD direction. For convenience, the direction perpendicular to both the RD direction and the HD direction is referred to as the lateral direction.

[0013] The protective cap 10 according to this embodiment functions as a protective cap that protects the tip of a reinforcing bar, as well as a protective cap that protects the tip of a pipe. As shown in FIGS. 1 to 5, the protective cap 10 includes a cap body 1. The cap body 1 has an axisymmetric shape with respect to a central axis X. The cap body 1 has a tubular portion 2 and a cap portion 3. The tubular portion 2 has a substantially rectangular cylindrical shape and is attached to at least one of a reinforcing bar and a pipe. The cap portion 3 is formed integrally with the tubular portion 2 at the end of the tubular portion 2 on the HDa side. In other words, the tubular portion 2 and the cap portion 3 are integral with each other.

[0014] The cylindrical portion 2 has a substantially rectangular cylindrical shape with the central axis X as its axis. The end of the cylindrical portion 2 on the HDb side is open, while the end on the HDa side is covered by the cap portion 3. The cylindrical portion 2 has four corners 21 and four side walls 22. In the substantially rectangular cylindrical shape of the cylindrical portion 2, the side walls 22 are side walls corresponding to each of the four sides of the rectangle. In addition, in the substantially rectangular cylindrical shape of the cylindrical portion 2, the corners 21 are walls connecting two adjacent side walls 22 to each other. The corners 21 are bent to connect to the two side walls 22. Here, the term "substantially rectangular cylindrical shape" includes not only a cylindrical shape having wall portions (corners) that are bent to connect to each of the two adjacent side walls that constitute the rectangular cylinder, but also a rectangular cylindrical shape in which four side walls are perpendicularly connected to each other.

[0015] The cap portion 3 is formed in a substantially hemispherical shape with the central axis X as its axis. The top portion 32 of the cap portion 3 is formed in a flat shape. In the substantially hemispherical shape of the cap portion 3, the surface on the HDb side is the inner ceiling surface 3a, and the surface on the HDa side is the outer peripheral surface 3b. It can be said that the cylindrical portion 2 extends from the inner ceiling surface 3a of the top portion 32 of the cap portion 3 to the HDb side.

[0016] The protective cap 10 according to this embodiment has a novel structure that differs from conventional protective caps. The novel structure of the protective cap 10 will be described below.

[0017] First, in the cap body 1, the cylindrical portion 2 has multiple inner ribs 4. The inner ribs 4 are provided on the inner peripheral surface 2a of the side wall 22, which has a substantially rectangular cylindrical shape, of the cylindrical portion 2. The inner ribs 4 extend from the inner ceiling surface 3a of the cap portion 3 toward the HDb side in the HD direction on the inner peripheral surface 2a of the side wall 22. The inner ribs 4 are convex strips that extend in the HD direction while protruding substantially perpendicular to the side wall 22. The distance between the tip of the inner rib 4 and the central axis X is substantially the same as the radius of the reinforcing bar to be installed. Two inner ribs 4 are provided for each of the four side walls 22.

[0018] When attaching the protective cap 10 to the tip of the rebar, the tip of the rebar is inserted into the open end of the tubular portion 2 on the HDb side, and the protective cap 10 is screwed in. When the protective cap 10 is screwed onto the tip of the rebar in this way, the side of the rebar engages with the inner ribs 4, and the rebar is clamped between the multiple inner ribs 4. This prevents the tip of the rebar from slipping out of the cap body 1 and falling off.

[0019] According to the protective cap 10 of this embodiment, the tubular portion 2 is not cylindrical but has a substantially rectangular tubular shape. This ensures that the tubular portion 2 is strong against the rebar when the protective cap 10 is screwed onto the rebar. Furthermore, the inner rib 4 is a convex strip that protrudes substantially perpendicular to the side wall 22 and extends toward the HDb side in the HD direction, and is not extremely inclined relative to the side wall 22. Therefore, even if the rebar shifts from its central axis or the cap body 1 rotates, the strength of the inner rib 4 is maintained, making the inner rib 4 less likely to crack. Furthermore, by adjusting the protruding length, thickness, and number of the inner ribs 4 relative to the side wall 22, the protective cap 10 can be used reliably at work sites where rebars of different diameters are used.

[0020] On the other hand, for example, in the protective cap of Utility Model Document 1, the inner ribs are formed so that their upper surfaces are positioned on the same arc. Furthermore, the tubular portion is cylindrical, and the inner ribs extend from the inner surface of the cylindrical portion in a direction tangent to the side surface of the rebar. In this configuration, the inner ribs are extremely inclined relative to the inner surface of the tubular portion, weakening the strength of the tubular portion and the inner ribs. Therefore, when screwing the protective cap onto the rebar, if the rebar shifts from its central axis or the protective cap rotates, the inner ribs are likely to crack. As a result, there is a risk that the tip of the rebar will slip out of the protective cap and fall off.

[0021] Furthermore, in the protective cap 10, the tubular portion 2 of the cap body 1 has a plurality of external ribs 5. The external ribs 5 are provided on the outer peripheral surfaces 2b of the corner portions 21 that connect the substantially rectangular tubular side walls 22 of the tubular portion 2. The external ribs 5 extend from the inner ceiling surface 3a of the cap portion 3 toward the HDb side in the HD direction on the outer peripheral surfaces 2b of the corner portions 21. The external ribs 5 are convex stripes that protrude from the corner portions 21 and extend in the HD direction. One external rib 5 is provided for each of the four corner portions 21.

[0022] When attaching the protective cap 10 to the tip of a pipe, the tubular portion 2 is inserted into the tip of the pipe until the HDb side surface of the peripheral edge 33 of the cap portion 3 reaches the end face of the tip of the pipe. This causes the outer rib 5 to contact the inner peripheral surface of the pipe and lock the pipe in place, so that the protective cap 10 can be stably attached to the tip of the pipe.

[0023] Additionally, an inclined portion 51 is provided at the end of the outer rib 5 on the HDb side. The inclined portion 51 is formed so that the outer rib 5 tapers toward the HDb side. The inclined portion 51 makes it easier to insert the tubular portion 2 into the tip of the pipe.

[0024] As described above, according to the protective cap 10 of this embodiment, the cylindrical portion 2 of the cap body 1, the inner rib 4, and the outer rib 5 have a new structure that differs from conventional protective caps.

[0025] Furthermore, in the protective cap 10, the cylindrical portion 2 has a cutout portion 23. The cutout portion 23 is formed on the HDb-side end surface 22a (lower end surface) of the substantially rectangular cylindrical side wall 22 of the cylindrical portion 2. The cutout portion 23 allows the weight of the protective cap 10 as a product to be reduced. Because the side wall 22 of the cylindrical portion 2 has a substantially rectangular cylindrical shape, there is less reduction in rigidity at the corner portions 21. Therefore, even when a rebar is screwed into the cylindrical portion 2 of the protective cap 10 to attach it, deformation of the cylindrical portion 2 is reduced, so the holding force of the protective cap 10 necessary to hold the rebar can be maintained. Therefore, the protective cap 10 can be attached to the rebar in a stable manner.

[0026] Furthermore, in the protective cap 10, the cap portion 3 has a plurality of recesses 31. The recesses 31 are formed on the outer peripheral surface 3b of the cap portion 3. The plurality of recesses 31 also have ellipsoidal surfaces 31a. The ellipsoidal surfaces 31a are concave surfaces recessed relative to the outer peripheral surface 3b. The ellipsoidal surfaces 31a have a major axis L extending from the top 32 of the cap portion 3 toward the peripheral edge 33. This major axis L is perpendicular to the R direction. On the outer peripheral surface 3b of the cap portion 3, the recesses 31 are formed at equal intervals from one another in the R direction. The recesses 31 make it easier for the worker to rotate the cap portion 3. Therefore, when attaching the cap body 1 to a pipe or rebar, the worker can easily screw the cap body 1 onto the tip of the pipe or rebar.

[0027] Furthermore, in the protective cap 10, the cap portion 3 has an uneven surface 34. The uneven surface 34 is formed by repeating unevenness in the R direction on the outer peripheral surface 3b of the peripheral edge portion 33. This prevents the cap body 1 from slipping off the worker's hand, even if the worker is wearing gloves while attaching the cap body 1 to a rebar or pipe. This allows the worker to smoothly attach or remove the cap body 1 to or from the rebar or pipe.

[0028] Here, the cap body 1 of the protective cap 10 is an injection-molded article. That is, the cylindrical portion 2 and the cap portion 3 are integrally injection-molded. As shown in FIGS. 1, 2, and 5, the cap body 1 has a side gate installation surface G (gate mark) formed during injection molding. The side gate installation surface G is located on the outer peripheral surface 3b of the peripheral portion 33 of the cap portion 3. The formation area of the side gate installation surface G partially overlaps with the formation area of the uneven surface 34, so the side gate installation surface G is formed by removing a portion of the uneven surface 34. That is, the cap portion 3 has the uneven surface 34 over the entire peripheral area of the outer peripheral surface 3b of the peripheral portion 33, excluding the side gate installation surface G. Because the side gate installation surface G is located on the outer peripheral surface 3b of the peripheral portion 33 of the cap portion 3, a side gate can be installed according to the shape of the uneven surface 34-forming portion of the peripheral portion 33 during injection molding of the cap body 1. Therefore, pressure loss during injection molding of the cap body 1 can be reduced.

[0029] Furthermore, the mold used for injection molding the cap body 1 preferably has a configuration in which an upper mold and a lower mold are separated in the HD direction. That is, it is preferable that the mold can be opened in the HD direction. Therefore, it is preferable that the outer rib 5 is formed so that the width W in the R direction decreases toward the HDb side in the HD direction. That is, it is preferable that the outer rib 5 is formed with a draft taper so that the width W in the R direction decreases. This makes it easier for the injection-molded body of the cap body 1 to be released from the mold when the mold is opened, and makes the injection molding of the cap body 1 smooth.

[0030] The above-mentioned configuration, (a) in which the side gate setting surface G is located on the outer peripheral surface 3b of the peripheral portion 33 of the cap portion 3, and (b) in which the outer rib 5 is formed so that the width W in the R direction decreases as it moves toward the HDb side in the HD direction, is particularly effective in terms of injection moldability when a polyhydroxyalkanoic acid resin is used as the base resin raw material for the cap body 1.

[0031] Furthermore, the dimensions of the tubular portion 2, the shed portion 3, the inner rib 4, and the outer rib 5 of the cap body 1 can be set appropriately depending on the diameter of the reinforcing bar or the diameter of the pipe to which the protective cap 10 is attached. The number of inner ribs 4 and outer ribs 5 can also be set appropriately depending on the diameter of the reinforcing bar or the diameter of the pipe to which the protective cap 10 is attached.

[0032] (Regarding the raw materials of the cap body 1) In the protective cap 10 according to this embodiment, the cap body 1 may contain any resin as long as the effect of improving the injection moldability described above is achieved. The cap body 1 preferably contains a biodegradable resin as a base resin.

[0033] Furthermore, the biodegradable resin is not particularly limited, but examples thereof include polyhydroxyalkanoic acid resins, polylactic acid, polyglycolic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polybutylene succinate terephthalate, and polycaprolactone. Among these, the biodegradable resin is preferably a polyhydroxyalkanoic acid resin (hereinafter sometimes referred to as a PHA resin). In this specification, "PHA resin" is a general term for polymers having hydroxyalkanoic acid as a monomer unit.

[0034] Particularly preferably, the PHA resin is a poly(3-hydroxyalkanoate) resin (hereinafter, sometimes referred to as a P3HA resin). In this specification, the term "P3HA resin" refers to a P3HA resin containing a 3-hydroxyalkanoic acid repeating unit represented by the general formula: [-CHR-CH2-CO-O-] (wherein R is C n H 2n+1 and n is an integer of 1 or more and 15 or less.) as a repeating unit.

[0035] More specifically, the P3HA resin preferably contains 3-hydroxybutyrate (3HB) units. The P3HA-based resin containing 3HB units is preferably selected from the group consisting of poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P3HB3HV), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P3HB3HV3HH), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), and combinations thereof. The P3HA-based resin may contain only one type, or two or more types.

[0036] The P3HA resin is preferably a P3HA resin produced by a microorganism (a microbially produced P3HA resin). A microbially produced P3HA resin is usually composed only of D-form (R-form) polyhydroxyalkanoate monomer units. Among the microbially produced P3HA resins, P3HB, P3HB3HH, P3HB3HV, P3HB3HV3HH, and P3HB4HB are preferred because of ease of industrial production, with P3HB, P3HB3HH, P3HB3HV, and P3HB4HB being more preferred.

[0037] P3HA-based resins can also be produced by, for example, the method described in WO 2010 / 013483. Commercially available P3HA-based resins include Kaneka Biodegradable Polymer PHBH (registered trademark) manufactured by Kaneka Corporation.

[0038] Furthermore, the P3HA-based resin contains at least one copolymer of 3HB units and other hydroxyalkanoate units, and the 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate)-based resin account for 65.0 to 99.0 mol % of all repeating units (100 mol %), preferably 68.0 to 98.5 mol %, more preferably 70.0 to 98.5 mol %, and even more preferably 70.0 to 98.0 mol %.

[0039] When the composition ratio of 3HB repeating units is 90.0 mol% or more, the rigidity of the P3HA-based resin is improved, the crystallization rate is accelerated, flash is reduced, and productivity tends to be improved. On the other hand, when the composition ratio of 3HB repeating units is 99.0 mol% or less, the melting point is below the thermal decomposition temperature, enabling stable and continuous production. The monomer composition ratio of the P3HA-based resin can be measured by gas chromatography or the like (see, for example, WO 2014 / 020838).

[0040] The molecular weight of the P3HA resin is not particularly limited as long as it exhibits substantially sufficient physical properties for the intended application. The weight-average molecular weight of the P3HA resin is preferably in the range of 100,000 to 1,000,000, more preferably 150,000 to 700,000, even more preferably 200,000 to 500,000, and particularly preferably 250,000 to 450,000. A weight-average molecular weight of 100,000 or more ensures adequate mechanical strength. Furthermore, a molecular weight of 1,000,000 or less can suppress an increase in melt viscosity, resulting in excellent moldability.

[0041] The weight-average molecular weight can be measured using gel permeation chromatography (GPC) (Shodex GPC-101 manufactured by Showa Denko K.K.) with a polystyrene gel column (Shodex K-804 manufactured by Showa Denko K.K.) and chloroform as the mobile phase, and can be calculated as a polystyrene-equivalent molecular weight. A calibration curve is prepared using polystyrenes with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. A column suitable for measuring the molecular weight can be used for the GPC.

[0042] Furthermore, in the protective cap according to this embodiment, the material of the cap body may contain additives that can be used with the thermoplastic resin, provided that the effects of the present invention are not impaired. Examples of such additives include inorganic fillers such as talc, calcium carbonate, mica, and silica; colorants such as pigments and dyes; odor absorbers such as activated carbon and zeolite; fragrances such as vanillin and dextrin; plasticizers; antioxidants; weather resistance improvers; UV absorbers; nucleating agents; lubricants; release agents; water repellents; antibacterial agents; and sliding properties improvers. Only one type of additive may be contained, or two or more types may be contained. The content of these additives can be appropriately determined by those skilled in the art depending on the intended use.

[0043] According to this embodiment, when P3HA-based resin is used as the raw material for the cap body, marine pollution due to disposal can be suppressed, thereby contributing to the achievement of Sustainable Development Goals (SDGs) such as Goal 12 "Ensure sustainable consumption and production patterns" and Goal 14 "Conserve and sustainably use the oceans and marine resources for sustainable development."

[0044] The cap body of the protective cap according to this embodiment is manufactured by injection molding. A conventionally known method can be used as the injection molding method. For example, when the cap body of the protective cap contains a P3HA-based resin, the cap body of the protective cap according to this embodiment can be manufactured by the injection molding technique disclosed in International Publication No. 2022 / 209602.

[0045] [Embodiment 2] Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0046] Fig. 6 is a perspective view from the side showing the configuration of the protective cap 10A according to this embodiment. Fig. 7 is a bottom view showing the configuration of the protective cap 10A according to this embodiment. Fig. 8 is a cross-sectional view taken along line AA shown in Fig. 7. Fig. 9 is a cross-sectional view taken along line BB shown in Fig. 7.

[0047] As shown in FIGS. 6 to 9 , the protective cap 10A according to this embodiment differs from the first embodiment in that the cap portion 3 has multiple protrusions 31A instead of recesses 31. The protrusions 31A are formed on the outer peripheral surface 3b of the cap portion 3. The multiple protrusions 31A have ellipsoidal surfaces 31b. The ellipsoidal surfaces 31b are convex surfaces that protrude relative to the outer peripheral surface 3b. The ellipsoidal surfaces 31b have a major axis L1 extending from the top 32 of the cap portion 3 toward the peripheral edge 33. This major axis L1 is perpendicular to the R direction. On the outer peripheral surface 3b of the cap portion 3, the protrusions 31A are formed at equal intervals in the R direction. The protrusions 31A make it easier for the worker to rotate the cap portion 3. Therefore, when attaching the cap body 1 to a pipe or reinforcing bar, the worker can easily screw the cap body 1 onto the tip of the pipe or reinforcing bar.

[0048] [Embodiment 3] Further, for the sake of convenience, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0049] Fig. 10 is a side view showing the configuration of a protective cap 10B according to this embodiment. As shown in Fig. 10, the protective cap 10B differs from the first and second embodiments in the configuration of the cap body 1B. In the cap body 1B, the outer peripheral surface 3b of the cap portion 3 does not have any recesses or protrusions for rotating the cap portion 3. This configuration is particularly effective in terms of the visibility of a colored marking when the outer peripheral surface 3b of the cap portion 3 is provided with the marking.

[0050] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0051] That is, one embodiment of the present invention is as follows.

[0052] <1> Protective caps 10, 10A, and 10B each include a cap body 1 having a cylindrical portion 2 of approximately rectangular cylindrical shape that is attached to at least one of a reinforcing bar and a pipe, and a shed portion 3 that is formed integrally with the cylindrical portion 2 at the upper end (the end on the HDa side) of the cylindrical portion 2, wherein the cylindrical portion 2 in the cap body 1 has an outer rib 5 that extends downward (toward the HDb side in the HD direction) from the inner ceiling surface 3a of the shed portion 3 on the outer surface 2b of the corner portion 21 that connects the approximately rectangular cylindrical side walls 22, and an inner rib 4 that extends downward (toward the HDb side in the HD direction) from the inner ceiling surface 3a of the shed portion 3 on the inner surface 2a of the approximately rectangular cylindrical side wall 22.

[0053] <2> The cylindrical portion 2 has a notch 23 formed in a lower end surface (end surface 22a on the HDb side) of the substantially rectangular cylindrical side wall 22. <1> Protective caps 10, 10A, 10B.

[0054] <3> The cap portion 3 has a plurality of recesses 31 or protrusions 31A formed on the outer peripheral surface 3b of the cap portion 3. <1> or <2> Protective cap 10, 10A.

[0055] <4> The plurality of recesses 31 or protrusions 31A have ellipsoidal surfaces 31a or 31b, and the ellipsoidal surfaces 31a or 31b have major axes L or L1 extending from the top 32 of the cap portion 3 toward the peripheral edge 33. <3> Protective cap 10, 10A.

[0056] <5> The outer rib 5 is formed so that its width W in the circumferential direction (R direction) becomes narrower as it goes downward (towards HDb in the HD direction). <1> ~ <4> One of the protective caps 10, 10A, and 10B.

[0057] <6> The cap body 1 is an injection-molded body, and a gate mark (side gate setting surface G) of the injection-molded body is on an outer peripheral surface 3b of a peripheral edge portion 33 of the cap portion 3, and the cap portion 3 has an uneven surface 34 over the entire peripheral region excluding the gate mark on the outer peripheral surface 3b of the peripheral edge portion 33. <1> ~ <5> One of the protective caps 10, 10A, and 10B.

[0058] <7> The cap body 1 contains a biodegradable resin as a base resin. <1> ~ <6> Protective cap for either

[0059] <8> The biodegradable resin is a polyhydroxyalkanoic acid resin. <7> Protective cap.

[0060] <9> The polyhydroxyalkanoic acid resin is a poly(3-hydroxyalkanoate) resin. <8> Protective cap.

[0061] <10> the poly(3-hydroxyalkanoate)-based resin is selected from the group consisting of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate), and combinations thereof; <9> Protective cap. [Explanation of symbols]

[0062] 1, 1B Cap body 2 Cylindrical part 2a Inner surface 2b Outer surface 21 Corner 22 Side wall 22a End face (lower end face) 23 Cutout 3 Kasabe 3a Ceiling interior 3b Outer surface 31 Recess 31A Convex part 31a, 31b elliptical sphere L, L1 long axis 32 Top 33 Periphery 34 Uneven surface 4 Inner rib 5 outer rib 10, 10A, 10B protective caps G Side gate setting surface G (gate mark)

Claims

1. a cylindrical portion having a substantially rectangular cylindrical shape that is attached to at least one of a reinforcing bar and a pipe; a cap body having a cap portion integrally formed with the cylindrical portion at an upper end of the cylindrical portion, In the cap body, The cylindrical portion is an outer rib extending downward from the inner ceiling surface of the cap portion on an outer peripheral surface of a corner portion connecting the substantially rectangular cylindrical side walls; The protective cap has an inner rib extending downward from the inner ceiling surface of the cap portion on the inner peripheral surface of the substantially rectangular cylindrical side wall.

2. The protective cap according to claim 1 , wherein the cylindrical portion has a notch formed in a lower end surface of the substantially rectangular cylindrical side wall.

3. The protective cap according to claim 1 , wherein the cap portion has a plurality of recesses or protrusions formed on an outer peripheral surface of the cap portion.

4. The protective cap according to claim 3 , wherein the plurality of recesses or protrusions have an ellipsoidal spherical surface, and the ellipsoidal spherical surface has a major axis extending from a top portion of the cap portion toward a peripheral edge portion thereof.

5. The protective cap according to claim 1 , wherein the outer rib is formed so that its circumferential width narrows downward.

6. the cap body is an injection molded body, a gate mark of the injection molded body is present on the outer peripheral surface of the peripheral edge of the cap portion; The protective cap according to claim 1 , wherein the cap portion has an uneven surface over the entire peripheral area of the outer circumferential surface of the peripheral edge portion excluding the gate mark.

7. The protective cap according to claim 1 , wherein the cap body contains a biodegradable resin as a base resin.

8. The protective cap according to claim 7 , wherein the biodegradable resin is a polyhydroxyalkanoic acid-based resin.

9. 9. The protective cap according to claim 8, wherein the polyhydroxyalkanoic acid resin is a poly(3-hydroxyalkanoate) resin.

10. 10. The protective cap of claim 9, wherein the poly(3-hydroxyalkanoate)-based resin is selected from the group consisting of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate), and combinations thereof.

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