JP6017274B2 - Shock absorbing member - Google Patents

Description

  The present invention relates to an impact-absorbing member mainly composed of a joined body obtained by joining members made of ceramics. More specifically, it is extremely useful as a component material for protective equipment, etc., which has the characteristics of being extremely hard and high in strength while being lightweight, and having the function of absorbing the energy of high-speed flying objects with high efficiency. The present invention relates to a shock absorbing member.

  In recent years, many proposals have been made on members that are excellent in impact energy absorption and the like, which are mainly composed of ceramics. For example, Patent Document 1 describes a protective member in which an impact receiving portion made of ceramics containing boron carbide as a main component and a base made of ceramics containing silicon nitride as a main component are combined with a bonding layer made of resin. ing. Patent Document 2 describes an impact absorbing member in which a partially stabilized zirconia sheet and a sheet made of boron carbide, mullite, or the like are laminated and bonded with an epoxy resin or the like.

  On the other hand, it is known that not only the impact absorbing member but also a highly functional structural material can be obtained by laminating members made of materials such as ceramics. For example, Patent Document 3 discloses a thermal shock that includes a base material made of ceramics or a sintered alloy, an intermediate layer made of ceramics, and an outermost layer made of ceramics whose thermal expansion coefficient is smaller than the thermal expansion coefficient of the base material. A laminated sintered body useful as a strong cutting tool is described. In addition, it is described that alumina, silicon nitride, boron nitride, silicon carbide, and the like are appropriately combined as the ceramic constituting the substrate and the outermost layer.

  Patent Document 4 describes a laminated structure sintered body useful as a cutting tool used under severe conditions, including metals, ceramics such as alumina, and cermet. Further, Patent Document 5 discloses a silicon nitride sintered body having a laminated structure in which a porous silicon nitride layer and a dense silicon nitride layer are laminated and has a high tolerance for impact force, stress, or strain. Is described. Patent Document 6 describes a joined body in which two ceramic members containing boron carbide are joined by heating to 600 ° C. or higher using a joining material containing a metal such as aluminum.

JP 2008-275208 A JP 2010-210217 A JP-A-4-319435 JP 7-137199 A JP-A-9-169571 International Publication No. 2012/029816

  In any of the above-described prior arts, a material having different characteristics or a material having different characteristics such as porosity even if the same material is combined is intended to express a target function. That is, conventionally, a member having desired characteristics has been obtained by selecting and combining a plurality of materials each having unique characteristics. However, there is a possibility that the manufacturing process becomes complicated and disadvantageous in terms of cost, or industrially impeded. For example, the protective member described in Patent Document 1 is heavier than, for example, a member composed only of boron carbide, and further has a problem in terms of strength. Moreover, the impact-absorbing member described in Patent Document 2 has a problem that it is heavier than a member composed only of boron carbide.

  Furthermore, the laminated sintered body described in Patent Document 3 is heavy as an impact absorbing member, and is manufactured under conditions such that firing is performed under pressure, so that it is difficult to increase the size. Moreover, since the laminated structure sintered body described in Patent Document 4 is manufactured using the chemical reaction heat of silicon, it is difficult to control the temperature and the like, and it is also difficult to increase the size. In addition, the silicon nitride sintered body described in Patent Document 5 has problems in terms of cost and size, and also has problems in stably supplying materials. Furthermore, the joined body described in Patent Document 6 is obtained by joining ceramic members to each other under a high temperature condition of 600 ° C. or higher. For this reason, there are problems in terms of cost and labor of manufacturing.

  The present invention has been made in view of such problems of the prior art, and the problem is that the high-speed flying object can be destroyed and the energy of the small pieces generated by being crushed Providing a shock absorbing member that is extremely useful as a component of protective equipment and can be easily manufactured with a light weight that can prevent the shock stress wave from coming back to the back side. There is to do.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have a Young's modulus within a predetermined range between the opposing joining surfaces of a plurality of first sheet-like members made of ceramics having a predetermined thickness. The present inventors have found that the above-described problems can be achieved by bonding with a bonding layer, and have completed the present invention.

That is, according to the present invention, the following impact absorbing member is provided.
[1] Arranged between a plurality of first sheet-like members having a thickness of 0.1 to 1 mm made of ceramics containing 60% by mass or more of boron carbide and the adjacent first sheet-like members. A ceramic joined body having a joining layer that joins the opposing joining surfaces of the first sheet-like member, and a plurality of the first sheet-like members are arranged in a stacking direction in the thickness direction. And the bonding layer is formed of an adhesive containing an organic resin, and the Young's modulus of the bonding layer is 50 MPa or more and less than 3100 MPa.
[2] The impact-absorbing member according to [1], wherein 2 to 1000 sheets of the first sheet-like member are stacked in the thickness direction.
[3] The impact absorbing member according to [2], wherein the thickness of the first sheet-like member increases stepwise from the front surface side to the back surface side of the ceramic joined body .
[4 ] The impact absorbing member according to any one of [1] to [ 3 ], wherein the bonding layer has a thickness of 0.01 to 1 mm.
[ 5 ] The impact-absorbing member according to any one of [1] to [ 4 ], further including a receiving layer that is disposed on the back surface side of the ceramic joined body and receives fragments generated at the time of breakage.
[6] the adhesive, epoxy resin adhesive, cyanoacrylate adhesive, modified silicone-based adhesive, and is at least one selected from the group consisting of polyurethane-based adhesives said [1] to [5 ] The impact-absorbing member according to any one of the above.

  The impact absorbing member of the present invention is a thin and lightweight plate-like member, but can sufficiently absorb the kinetic energy of the colliding high-speed flying object. Furthermore, it is possible to destroy the colliding high-speed flying object, minimizing the energy of the small pieces generated by being crushed, and reliably preventing the shock wave from escaping to the back side (back). it can. And since it can manufacture simply, it is excellent also economically. In particular, by appropriately combining the thickness of the sheet-like member (plate-like member) made of ceramics containing boron carbide and the number of laminated layers, the kinetic energy of the high-speed flying object compared to the members described in Patent Documents 1 and 2 above. An impact-absorbing member having high functionality and high functionality in which the outermost surface is difficult to break when a high-speed flying object collides is provided.

It is a fragmentary sectional view showing typically one embodiment of an impact-absorbing member of the present invention. FIG. 1B is a partially enlarged view of the shock absorbing member shown in FIG. 1A. It is a fragmentary sectional view showing typically other embodiments of an impact-absorbing member of the present invention. It is a fragmentary sectional view showing typically other embodiment of an impact-absorbing member of the present invention typically.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments for carrying out the present invention. In the prior art, boron carbide is simply selected as a constituent material of the shock absorbing member from the viewpoints of weight reduction, high strength, and high hardness. On the other hand, the present inventors efficiently absorb the kinetic energy of the high-speed flying object in order to make the member capable of exhibiting an excellent function as a protector while maintaining light weight, It has come to the recognition that it is important to ensure that damage to people, vehicles, etc. existing inside the shock absorbing member due to the fragments generated at the time of high-speed flying object collision can be reduced. And the present inventors performed various examination about the boron carbide as a constituent material of an impact-absorbing member from this recognition.

  As a result, a plurality of sheet-like (thin plate-like) members made of ceramics whose main component is boron carbide are laminated, and the joining surfaces of the sheet-like members are joined together by a joining layer whose Young's modulus is within a predetermined range. It has been found that the resulting bonded body has a significantly different impact absorption capacity compared to a non-bonded plate of the same thickness (non-bonded body). Such a joined body statically exhibited almost the same mechanical characteristics as a non-joined body. However, this joined body can destroy the high-speed flying object at the time of collision with the high-speed flying object, and at the same time, can absorb the kinetic energy of the high-speed flying object with high efficiency. Further, since the surface is finely broken, the spread of the shock wave is suppressed, and the shape of the surface on which the high-speed flying object collides can be easily maintained. Note that the impact absorbing member of the present invention can destroy the colliding high-speed flying object by joining a plurality of sheet-like members with a joining layer having a predetermined Young's modulus, and at the same time, the impact wave passing through the impact absorbing member. It is considered that the progress is hindered by a high stress field existing inside the ceramic joined body. Further, as a result of the study, the present inventors have found that the kinetic energy of a high-speed flying object can be converted into surface energy more efficiently by making the sheet-like member thinner and increasing the number of laminated sheets.

  Boron carbide has been conventionally used as a constituent material for impact absorbing members. However, since boron carbide is an extremely expensive material, it has been used only in situations where high-speed flying objects having extremely high kinetic energy can collide. On the other hand, the impact absorbing member of the present invention can reduce the thickness of the ceramic joined body obtained by joining a plurality of sheet-like members containing boron carbide. For this reason, it is possible to reduce the weight and greatly contribute to cost reduction. That is, as a result of weight reduction, energy consumption during movement or transportation during use can be reduced. For this reason, the burden on a human body or a vehicle can be reduced. Furthermore, since the sheet-like member can be thinned, it is possible to shorten the time for the firing process and the like. Further, even when the surface is formed with an uneven surface, it is extremely advantageous in terms of cost. Therefore, the manufacturing cost is lower than that of a conventional shock absorbing member, and its practical value is extremely high. Therefore, the impact absorbing member of the present invention is expected to be employed in various technical fields as well as in situations where high-speed flying objects may collide.

  FIG. 1A is a partial cross-sectional view schematically showing an embodiment of the shock absorbing member of the present invention. FIG. 1B is a partially enlarged view of the impact absorbing member shown in FIG. 1A. As shown in FIGS. 1A and 1B, the shock absorbing member 50 of the present embodiment includes a bonding layer 65 disposed between a plurality of first sheet-like members 5 made of ceramics and an adjacent first sheet-like member. And a ceramic joined body 15 having the following. The 1st sheet-like member 5 is laminated | stacked and arrange | positioned in the thickness direction. The bonding layer 65 bonds the bonding surfaces 5a and 5b facing each other between the adjacent first sheet-like members 5. The ceramic which is a constituent material of the first sheet-like member 5 contains boron carbide in an amount of 60% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more. By laminating the first sheet-like member formed of ceramics containing boron carbide, extremely excellent shock absorption can be obtained. In addition, although the upper limit of the ratio of the boron carbide contained in ceramics is not specifically limited, It is most preferable that it is 100 mass%.

  The thickness of the 1st sheet-like member 5 is 0.1-50 mm, Preferably it is 1-10 mm. If the thickness of the first sheet-like member is less than 0.1 mm, it may be too thin to be practical in production. On the other hand, if the thickness of the first sheet-like member is more than 50 mm, the impact absorbability is lowered.

  The number of the first sheet-like members constituting the ceramic bonded body is not particularly limited as long as it is plural, but is usually 2 to 1000, preferably 5 to 50. If the number of first sheet-like members stacked is too small, the effect obtained by stacking may be insufficient. On the other hand, when the number of laminated first sheet-like members is too large, the effect reaches a peak and the obtained ceramic joined body becomes heavy, and the handleability as a protective device tends to be lowered.

  Boron carbide contained in the ceramics constituting the first sheet-like member 5 has high hardness and low specific gravity. For this reason, the 1st sheet-like member 5 arrange | positioned on the outermost surface which a high-speed flying object collides can destroy the high-speed flying object which collided by the characteristic of boron carbide. The ceramic joined body 15 formed by laminating and joining a plurality of first sheet-like members exhibits the mechanical characteristics of boron carbide and has a high stress field at the joining interface. For this reason, when the high-speed flying object collides, the kinetic energy of the high-speed flying object is absorbed by the first sheet-like member 5 being finely broken. In addition, it is preferable that the relative density of the 1st sheet-like member consisting of boron carbide is a dense material of 89% or more. As described above, a ceramic joined body obtained by laminating and joining a plurality of first sheet-like members made of ceramics mainly composed of boron carbide has a high stress field therein. This stress field deflects a shock wave at the time of collision of a high-speed flying object passing through the ceramic bonded body. Thereby, the impact to the inside of the shock absorbing member of the present invention is remarkably reduced.

  The Young's modulus of the bonding layer 65 is 50 to 5000 MPa, preferably 50 to 4000 MPa, and more preferably 70 to 3500 MPa. By joining the joining surfaces 5a and 5b of the first sheet-like member 5 with the joining layer 65 having a Young's modulus in the above numerical range, the progress of the shock wave passing through the impact absorbing member is inhibited by a high stress field, The kinetic energy of a high-speed flying object can be converted into surface energy more efficiently. If the Young's modulus of the bonding layer is less than 50 MPa, the adhesive strength also decreases. For this reason, the impact absorption characteristics are lowered, and it may be difficult to maintain the shape of the impact absorbing member itself. On the other hand, if the Young's modulus of the bonding layer is more than 5000 MPa, the impact absorption characteristic is maintained at a high level, but it is necessary to form the bonding layer under a high temperature condition using a metal such as aluminum. For this reason, it takes time for manufacturing and there are problems in terms of cost.

The “Young's modulus” (longitudinal elastic modulus) in this specification means a value measured by a tensile method, and is calculated according to the following formula (1).
Young's modulus (MPa) E = (ΔF × L) / (S × ΔL) (1)
ΔF: Load increase (N)
L: Initial length (mm)
S: sectional area (mm ² )
ΔL: Length increase (mm)

  As a material (bonding material) for forming a bonding layer having a Young's modulus within the above numerical range, for example, an adhesive containing an organic resin is used in consideration of strength, specific gravity, process simplicity, and the like. it can. Specific examples of such an adhesive include an epoxy resin adhesive, a cyanoacrylate adhesive, and a modified silicone adhesive. In addition, these adhesive agents can be used individually by 1 type or in combination of 2 or more types.

  The epoxy resin contained in the epoxy resin adhesive is a polymer having two or more oxirane rings (epoxy groups) in one molecule, and a cured product (joining layer) that has been three-dimensionalized with an appropriate curing agent. Form. Epoxy resins include bisphenol A type, bisphenol F type, and bisphenol AD type, and any epoxy resin may be used. The properties of the cured product (bonding layer) formed by the epoxy resin vary greatly depending on the type of curing agent. As the curing agent, for example, an amine-based curing agent made of an amine compound is used. Examples of amine compounds include aliphatic, alicyclic, and aromatic amines depending on the type of hydrocarbon. Aliphatic amines are fast reactive and can be cured at room temperature. Moreover, the heat resistance of the obtained hardened | cured material is about 100 degreeC. On the other hand, an aromatic amine can be cured at 100 to 200 ° C., and a cured product having higher heat resistance and excellent chemical resistance such as alkali resistance can be obtained than when an aliphatic amine is used.

  The cyanoacrylate-based adhesive starts anionic polymerization at room temperature with a small amount of moisture in the atmosphere, and becomes a high-molecular polymer and cures in a short time. For this reason, if a cyanoacrylate adhesive is used as a bonding material, a ceramic bonded body can be manufactured in a short time.

  The modified silicone adhesive is a polypropylene oxide liquid polymer having a reactive silyl functional group at its molecular end. The cured product of the modified silicone adhesive is a flexible and tough rubber-like elastic body. For this reason, if a modified silicone adhesive is used as the bonding material, it is possible to manufacture an impact absorbing member with improved impact absorbing ability.

  The polyurethane resin adhesive is an adhesive made of a polyurethane resin obtained by a reaction between polyisocyanate and polyol. The cured product of this polyurethane resin adhesive is a copolymer consisting of a hard segment composed of repeating units of urethane groups and urea groups and a soft segment having high flexibility, and the hard segment acts as a physical crosslink, The segment acts as an elastic element. Due to the presence of this soft segment, if a polyurethane resin adhesive is used, it is possible to produce an impact absorbing member with improved impact absorbing ability.

  The bending strength of the ceramic joined body 15 constituting the impact absorbing member 50 of the present embodiment is preferably 100 MPa or more. In addition, the “bending strength” in the present specification means a physical property value of a ceramic joined body including a joint portion measured by a four-point bending method.

  The thickness of the bonding layer 65 is preferably 0.01 to 1 mm, more preferably 0.02 to 0.7 mm, and particularly preferably 0.02 to 0.5 mm. The thickness of the bonding layer can be adjusted, for example, by changing the amount (thickness) of the adhesive used. If the thickness of the bonding layer is less than 0.01 mm, the bonding strength may be insufficient. On the other hand, if the thickness of the bonding layer is more than 1 mm, the bonding strength may be insufficient due to the excessive amount of adhesive and the ceramic floating.

  Since boron carbide is lightweight and has a low fracture toughness value, it breaks up more finely when an impact is applied. For this reason, boron carbide is suitable as a material for constituting the shock absorbing member of the present invention. In addition, the present inventors have already developed the technique which produces boron carbide economically (refer international publication 2008/153177). If this technique is utilized, not only a sheet-like member but various shaped members made of boron carbide can be provided at a lower cost.

  In the impact-absorbing member of the present invention, it is preferable that the ceramic joined body further includes one or more second sheet-like members arranged by being laminated on the first sheet-like member via a joining layer. Examples of the material constituting the second sheet-like member include ceramics such as silicon carbide, mullite, and alumina. When a ceramic joined body is configured by combining the second sheet-like member made of these ceramics with the first sheet-like member, the impact on the inside (human body, vehicle, etc.) of the second sheet-like member is further mitigated. Therefore, it is more useful as a component of the protective equipment. This is because the second sheet-shaped member made of the above ceramics has a high ability to convert the kinetic energy of the high-speed flying object into surface energy.

  FIG. 2 is a partial cross-sectional view schematically showing another embodiment of the impact absorbing member of the present invention. The impact absorbing member 55 of the embodiment shown in FIG. 2 includes a ceramic joined body 15 in which a plurality of first sheet-like members 5 are joined via a joining layer (not shown), and a back surface side of the ceramic joined body 15. And a receiving layer made up of the third sheet-like member 30 and the fourth sheet-like member 40. By providing such a receiving layer on the back side of the ceramic joined body, it is possible to more reliably receive debris generated by breakage of the ceramic joined body and make it less likely to penetrate through the back side. FIG. 2 shows a state in which the receiving layer 70 composed of the third sheet-like member 30 and the fourth sheet-like member 40 is arranged. However, the receiving layer 70 is composed only of the third sheet-like member. Alternatively, it may be composed of only the fourth sheet-like member.

  Examples of the material constituting the third sheet-like member 30 include high-strength fibers such as aramid fibers. Moreover, as a material which comprises the 4th sheet-like member 40, the metal with small specific gravity like aluminum and magnesium can be mentioned. These materials constituting the third sheet-like member and the fourth sheet-like member are often provided in a plate shape and are preferable materials because of their low cost. In addition, the 4th sheet-like member comprised with the metal etc. is good to arrange | position on the side (back side) furthest from the outermost surface which opposes the person or vehicle etc. used as protection object.

  FIG. 3 is a partial cross-sectional view schematically showing still another embodiment of the impact absorbing member of the present invention. The impact absorbing member 60 of the embodiment shown in FIG. 3 includes a ceramic joined body 25, and a third sheet-like member 30 and a fourth sheet-like member that are disposed on the back side of the ceramic joined body 25 and serve as a receiving layer. 40. And this ceramic joined body 25 is comprised so that the thickness of the 1st sheet-like members 10 and 20 may increase in steps toward the back surface side from the surface side. Thus, by increasing (thickening) the thickness of the sheet-like members 10 and 20 stepwise from the front surface side to the back surface side, a distribution occurs in the inherent stress field. For this reason, the propagation direction of the shock wave generated at the time of the collision of the high-speed flying object is deflected, and the size of the ceramic piece generated by the breakage of the ceramic joined body is controlled, and the scattering to the back side is more effectively prevented. The

  A case is assumed in which a high-speed flying object collides with the surface side (the side on which the first sheet-like member 10 is disposed) of the impact absorbing member 60 shown in FIG. In this case, the high-speed flying object colliding with the first sheet-like member 10 is destroyed, and the ceramic containing boron carbide constituting the first sheet-like member 10 is finely destroyed. For this reason, the kinetic energy of the high-speed flying object is efficiently absorbed. Moreover, the thicker 1st sheet-like member 20 arrange | positioned at the back side of the 1st sheet-like member 10 is damaged by the attenuated shock wave, and a big fragment is formed. As a result, the kinetic energy of the high-speed flying object is almost completely absorbed. The fragments generated by the breakage of the ceramic joined body 25 are absorbed by the third sheet-like member 30 and the fourth sheet-like member 40 which are the receiving layers 70 disposed on the back side of the ceramic joined body 25, and Do not penetrate to the side. The ceramic joined body 25 is configured such that the thickness of the first sheet-like members 10 and 20 increases stepwise from the front surface side toward the back surface side, thereby making the thickness of the ceramic joined body 25 thinner. This makes it possible to significantly reduce the weight of the shock absorbing member 60 while maintaining the same or higher function than the conventional one.

  As described above, the first sheet-like member 5 constituting the impact absorbing member 50 shown in FIG. 1A is arranged in a stacked manner in the thickness direction. However, in the present invention, the plurality of first sheet-like members are not limited to being stacked and arranged in the thickness direction, and may be arranged in the horizontal direction, for example. When a plurality of first sheet-like members are arranged side by side in the horizontal direction, the bonding layer is arranged between the end faces (narrow end faces) of the adjacent first sheet-like members, and the adjacent first sheet-like members are arranged. Join each other. By comprising in this way, it becomes possible to make the shape of the impact-absorbing member of this invention into a bending shape. For this reason, for example, it is possible to easily obtain an impact-absorbing member molded in accordance with a bent shape such as a human shoulder or elbow.

  Next, the manufacturing method of the impact-absorbing member of this invention is demonstrated. The method for producing an impact absorbing member of the present invention includes a step of laminating a plurality of first sheet-like members in the thickness direction via a bonding material to obtain a laminate (lamination step), and joining of the obtained laminates Curing a material to form a bonding layer, and obtaining a ceramic bonded body (bonding step).

  In the laminating step, a bonding material is disposed on a portion (bonding surface) where the first sheet-like members are bonded to each other. As the bonding material, for example, an adhesive containing the aforementioned organic resin can be used. The thickness of the bonding material to be arranged may be approximately 1 mm or less. In this way, a plurality of first sheet-like members are laminated in the thickness direction via the adhesive material to obtain a laminate.

  In the joining step, the joining material of the laminate obtained by the above-described lamination step is cured to form a joining layer. When the bonding material is an adhesive containing an organic resin, the bonding material can be cured by leaving it under room temperature conditions, or at least heating at a temperature of 70 to 200 ° C. at which the bonding portions are bonded. When the bonding layer is formed in this manner, a ceramic bonded body can be obtained. The obtained ceramic joined body may be used as it is as an impact absorbing member, or the impact absorbing member may be configured by appropriately arranging a second sheet-like member, a receiving layer, or the like.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified.

(Production of first sheet-like member)
After filling commercially available boron carbide (B ₄ C) powder into a 9 cm square mold and pressurizing at a pressure of 200 kg / cm ² , hydrostatic pressing is performed at a pressure of 1000 kg / cm ² , and after firing and processing A boron carbide molded body having a thickness of 0.1 to 50 mm was obtained. The boron carbide powder used had an average particle size of 0.8 μm and a purity of 99.5% (excluding oxygen content of 1.2% and nitrogen content of 0.2%). The obtained boron carbide molded body was placed in a firing furnace in which aluminum and silicon were arranged, and was fired under normal pressure at 2200 ° C. for 4 hours while flowing argon (Ar) gas to obtain a fired body. The fired bodies obtained so as to have a thickness of 0.1 to 50 mm were ground using a diamond grindstone to obtain 7 cm square first sheet-like members made of boron carbide. All of the obtained first sheet-like members were extremely dense with a relative density of 95% or more.

(Preparation of receiving layer)
A plurality of 1 mm thick sheets composed of aramid fibers (Kevlar: registered trademark, manufactured by DuPont) made of a commercially available aromatic aramid resin are laminated and integrated with an epoxy resin, a thickness of 3 mm, A 7 cm square third sheet-like member was prepared. In addition, an aluminum metal plate having a thickness of 4 mm and a 7 cm square was prepared and used as a fourth sheet-like member.

Example 1
A first sheet having a thickness of 0.1 mm is prepared by mixing a bisphenol A type liquid epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd.) and an amine curing agent (manufactured by Mitsui Chemicals Fine Co., Ltd.) at a ratio of 2: 1. After apply | coating to each joining surface of 100 members, the 1st sheet-like member was laminated | stacked and the laminated body was obtained. The obtained laminate was heated from room temperature to 125 ° C. over 1 hour and 30 minutes, and then held at 125 ° C. for 3 hours to cure the epoxy resin to obtain a ceramic joined body having a thickness of about 12 mm. The obtained ceramic joined body was used as an impact absorbing member (Example 1). In addition, it was 2400 MPa when the Young's modulus of the sample obtained by hardening | curing only an epoxy resin on said conditions was measured with the tension method.

(Examples 2 and 3, Reference Examples 4 and 5, Comparative Example 1)
Except that the thickness and number of sheets of the first sheet-like member are as shown in Table 1, the shock absorbing member (Example) which is a ceramic joined body having a thickness of about 10 to 12 mm, as in Example 1 above. 2 , 3, Reference Examples 4, 5, and Comparative Example 1) were obtained.

( Reference Example 6)
A cyanoacrylate adhesive (trade name “Aron Alpha” (registered trademark, manufactured by Toagosei Co., Ltd.)) is applied to each joint surface of 10 sheets of the first sheet-like member having a thickness of 1 mm, and then the first sheet-like form The member was laminated | stacked and the laminated body was obtained. The obtained laminate was held at room temperature for 2 hours to cure the adhesive, and a ceramic joined body having a thickness of about 10.3 mm was obtained. The obtained ceramic joined body was used as an impact absorbing member ( Reference Example 6). The Young's modulus of a sample obtained by curing only the cyanoacrylate adhesive was measured by a tensile method and found to be 3100 MPa.

(Example 7)
After applying a modified silicone adhesive (trade name “PM165” (Cemedine Co., Ltd.)) to each joint surface of 10 sheets of the first sheet member having a thickness of 1 mm, the first sheet member is laminated. To obtain a laminate. The obtained laminate was held at room temperature for 2 hours to cure the adhesive, and a ceramic joined body having a thickness of about 10.5 mm was obtained. The obtained ceramic joined body was used as an impact absorbing member (Example 7). The Young's modulus of a sample obtained by curing only the modified silicone adhesive was measured by a tensile method and found to be 100 MPa.

(Example 8)
10 sheets of 1 mm-thick first sheet-like member in which A and B agents of trade name “PU-62” (manufactured by Toagosei Co., Ltd.), which is a polyurethane resin adhesive, are mixed at a ratio of 10: 8. After apply | coating to each joining surface of this, the 1st sheet-like member was laminated | stacked and the laminated body was obtained. The obtained laminate was heated from room temperature to 80 ° C. over 1 hour, and then held at 80 ° C. for 30 minutes to cure the adhesive to obtain a ceramic joined body having a thickness of about 10.2 mm. The obtained ceramic joined body was used as an impact absorbing member (Example 8). The Young's modulus of a sample obtained by curing only the polyurethane resin-based adhesive under the above conditions was measured by a tensile method and found to be 70 MPa.

(Comparative Example 2)
A first sheet-like member having a thickness of 10 mm, which was not joined using an adhesive, was used as an impact absorbing member (Comparative Example 2).

(Comparative Example 3)
Ten first sheet-like members having a thickness of 1 mm were laminated with an aluminum film having a thickness of 10 μm (purity: 99%) interposed therebetween to obtain a laminate. The obtained laminate was heated in vacuum at 700 ° C. for 2 hours, and the first sheet-like member was joined to obtain a ceramic joined body having a thickness of about 10 mm. The obtained ceramic joined body was used as an impact absorbing member (Comparative Example 3). The tensile modulus of the aluminum film was 71000 MPa.

(Comparative Example 4)
After an ethylene / vinyl acetate copolymer adhesive (manufactured by Nihon Unicar) is applied to each joint surface of 10 sheets of the first sheet-like member having a thickness of 1 mm, the first sheet-like member is laminated and laminated. Got the body. The obtained laminate was heated from room temperature to 125 ° C. over 1 hour and 30 minutes, then held at 125 ° C. for 30 hours to cure the adhesive, and a ceramic joined body having a thickness of about 10.1 mm was obtained. It was. The obtained ceramic joined body was used as an impact absorbing member (Comparative Example 4). The Young's modulus of a sample obtained by curing only the ethylene / vinyl acetate copolymer adhesive under the above conditions was 20 MPa.

(Impact fracture test (1))
An impact fracture test was performed using a gas accelerator that transmits the pressure of the compressed gas to the flying object and causes the flying object that passed through the launch tube to collide with the sample. As the flying object, bearing steel having a diameter of 4 mmφ was used. In addition, the flying object collided and penetrated the sample (impact absorbing member) at almost the speed of sound, and the damaged volume (cm ³ ) and the average diameter (mm) of the generated small pieces were measured. The results are shown in Table 1.

(Evaluation)
As shown in Table 1, with respect to the impact absorbing member manufactured using an epoxy resin adhesive, the thinner the first sheet-like member, the smaller the damaged volume at the location where it was destroyed in a cone shape, and the small pieces produced by the destruction The average diameter became smaller (Examples 1 to 3, Reference Examples 4 and 5, Comparative Example 2). In addition, even when a cyanoacrylate adhesive, a modified silicone adhesive, and a polyurethane resin adhesive were used, the damaged volume was almost the same as when an epoxy resin adhesive was used ( Reference Example 6 , Examples 7, 8). On the other hand, the impact absorbing member of Comparative Example 1 was damaged as if the joint surfaces of the first sheet-like members were peeled off, and it was impossible to measure the damaged volume and the average diameter of the small pieces. It was. Moreover, the impact-absorbing member of Comparative Example 2 was found to have a large damaged volume because large pieces were scattered backward. In the impact absorbing member of Comparative Example 2, cracks were generated in the vertical and horizontal directions on the surface where the flying object collided, whereas in the impact absorbing member of Example 1, almost no vertical and horizontal cracks were observed.

  Further, the shock absorbing member of Comparative Example 3 had substantially the same shock absorbing characteristics as the shock absorbing member of Example 3. However, in order to manufacture the shock absorbing member of Comparative Example 3, it is necessary to perform heat treatment at a high temperature as high as 700 ° C. Therefore, there is a problem that the manufacturing cost is excessive as compared with the case of manufacturing the shock absorbing member of Example 3. . On the other hand, the impact absorbing member of Comparative Example 4 showed a peculiar fracture behavior such that the adhesive strength between the first sheet-like members was low and the forefront surface of the first sheet-like member was severely damaged. The average diameter could not be measured.

( Reference Example 9)
A first sheet-like member 20 having a thickness of 5 mm is prepared by mixing a bisphenol A liquid epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd.) and an amine curing agent (manufactured by Mitsui Chemicals Fine Co., Ltd.) in a ratio of 2: 1. After apply | coating to each joining surface of a sheet | seat, the 1st sheet-like member was laminated | stacked and the laminated body was obtained. The obtained laminate was heated from room temperature to 125 ° C. over 1 hour and 30 minutes, then held at 125 ° C. for 3 hours to cure the epoxy resin, and a ceramic joined body having a thickness of about 100.4 mm was obtained. It was. The obtained ceramic joined body was used as an impact absorbing member ( Reference Example 9). In addition, it was 2400 MPa when the Young's modulus of the sample obtained by hardening | curing only an epoxy resin on said conditions was measured with the tension method.

( Reference Examples 10-12)
Except that the thickness and the number of sheets of the first sheet-like member are as shown in Table 2, the impact absorbing member which is a ceramic joined body having a thickness of about 100 to 100.2 mm is the same as in Reference Example 9 described above. Reference examples 10 to 12) were obtained.

( Reference Example 13)
After a cyanoacrylate adhesive (trade name “Aron Alpha” (registered trademark, manufactured by Toagosei Co., Ltd.)) is applied to each joining surface of 20 sheets of the first sheet-like member having a thickness of 5 mm, the first sheet-like adhesive is applied. The member was laminated | stacked and the laminated body was obtained. The obtained laminate was held at room temperature for 2 hours to cure the adhesive, and a ceramic joined body having a thickness of about 100.6 mm was obtained. The obtained ceramic joined body was used as an impact absorbing member ( Reference Example 13). The Young's modulus of a sample obtained by curing only the cyanoacrylate adhesive was measured by a tensile method and found to be 3100 MPa.

( Reference Example 14)
After applying the modified silicone adhesive (trade name “PM165” (Cemedine)) to each of the 20 sheets of the first sheet-like member having a thickness of 5 mm, the first sheet-like member is laminated. To obtain a laminate. The obtained laminate was held at room temperature for 2 hours to cure the adhesive, and a ceramic joined body having a thickness of about 101 mm was obtained. The obtained ceramic joined body was used as an impact absorbing member ( Reference Example 14). The Young's modulus of a sample obtained by curing only the modified silicone adhesive was measured by a tensile method and found to be 100 MPa.

( Reference Example 15)
20 sheets of a first sheet-like member having a thickness of 5 mm, which is a mixture of A and B agents of trade name “PU-62” (manufactured by Toagosei Co., Ltd.), which is a polyurethane resin adhesive, in a ratio of 10: 8 After apply | coating to each joining surface of this, the 1st sheet-like member was laminated | stacked and the laminated body was obtained. The obtained laminate was heated from room temperature to 80 ° C. over 1 hour, and then held at 80 ° C. for 30 minutes to cure the adhesive to obtain a ceramic joined body having a thickness of about 100.4 mm. The obtained ceramic joined body was used as an impact absorbing member ( Reference Example 15). The Young's modulus of a sample obtained by curing only the polyurethane resin-based adhesive under the above conditions was measured by a tensile method and found to be 70 MPa.

(Comparative Example 5)
A first sheet-like member having a thickness of 100 mm that was not joined using an adhesive was used as an impact absorbing member (Comparative Example 5).

(Impact fracture test (2))
A destructive test was performed in the same procedure as the “impact destructive test (1)” except that the flying object collided with the sample (impact absorbing member) at a speed about three times the sound speed. In any of the impact absorbing members ( Reference Examples 9 to 15 and Comparative Example 5), since the flying object did not penetrate, the surface on which the flying object collided was visually observed to determine “crack degree” and “crack interval”. Was evaluated. The results are shown in Table 2.

(Evaluation)
As shown in Table 2, in the shock absorbing member of Comparative Example 5, many cracks occurred and the interval between cracks was narrow. On the other hand, in the impact absorbing members of Reference Examples 9 to 12, the more the number of the first sheet-like members stacked, and the thinner the first sheet-like member, the fewer cracks generated and the wider the interval. Tended to be. Moreover, also when a cyanoacrylate adhesive, a modified silicone adhesive, and a polyurethane resin adhesive were used, the same results were obtained as when an epoxy resin adhesive was used ( Reference Examples 13 to 15). ).

(Example 16)
A ceramic joined body (thickness: about 10.2 mm) prepared in Example 3, a sheet made of aramid fibers, laminated with an epoxy resin (thickness 10 mm), and an aluminum metal plate (thickness 10 mm) ) Were laminated in this order to produce a shock absorbing member (Example 16) having a layer structure as shown in FIG. 1B.

(Comparative Example 6)
A first sheet-like member having a thickness of 10 mm used in Comparative Example 2 and a sheet made of aramid fibers were laminated and integrated with an epoxy resin (thickness 10 mm), and an aluminum metal plate (thickness 10 mm) ) Were laminated in this order to produce an impact absorbing member (Comparative Example 6).

(Evaluation)
The impact absorbing member of Example 16 and Comparative Example 6 was subjected to the aforementioned “impact breaking test (1)”. As a result, the flying object was destroyed on the surface of any shock absorbing member. However, the back surface (aluminum metal plate) of the shock absorbing member was in a different situation. In the impact absorbing member of Comparative Example 6, a hole having a diameter of about 2 mm was formed in the aluminum metal plate. On the other hand, in the impact absorbing member of Example 16, no change in appearance was observed in the aluminum metal plate.

(Example 17)
A first sheet having a thickness of 0.5 mm is prepared by mixing a bisphenol A type liquid epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd.) and an amine curing agent (manufactured by Mitsui Chemicals Fine Co., Ltd.) in a ratio of 2: 1. After apply | coating to each joining surface of four members, the 1st sheet-like member was laminated | stacked and the laminated body was obtained. The obtained laminate was heated from room temperature to 125 ° C. over 1 hour and 30 minutes, and then held at 125 ° C. for 3 hours to cure the epoxy resin to obtain a ceramic joined body having a thickness of about 2.06 mm. It was. The obtained ceramic joined body, sheets made of aramid fibers are laminated, a sheet integrated with an epoxy resin (thickness 10 mm), and an aluminum metal plate (thickness 10 mm) are laminated in this order, and FIG. An impact absorbing member (Example 17) having a layer structure as shown was produced.

(Evaluation)
The impact absorbing member of Example 17 was subjected to the aforementioned “impact fracture test (1)”. As a result, the flying object was destroyed on the surface of the shock absorbing member, and no change in the appearance of the aluminum metal plate was observed.

(Example 18)
Four first sheet-like members having a thickness of 0.5 mm are mixed with a bisphenol A type liquid epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd.) and an amine curing agent (manufactured by Mitsui Chemicals Fine Co., Ltd.) in a ratio of 2: 1. Lamination was performed with the mixed material interposed. Furthermore, five first sheet-like members having a thickness of 1 mm were laminated with the mixture of the epoxy resin and the curing agent interposed therebetween to obtain a laminate. The obtained laminate was heated from room temperature to 125 ° C. over 1 hour and 30 minutes, and then held at 125 ° C. for 3 hours to cure the epoxy resin to obtain a ceramic joined body having a thickness of about 7.14 mm. The obtained ceramic joined body, sheets made of aramid fibers were laminated, a sheet integrated with an epoxy resin (thickness 10 mm), and an aluminum metal plate (thickness 10 mm) were laminated in this order, and FIG. A shock absorbing member (Example 18) having a layer structure as shown was produced.

(Evaluation)
The impact absorbing member of Example 18 was subjected to the aforementioned “impact fracture test (1)”. As a result, the flying object was destroyed on the surface of the impact absorbing member, and no change in the appearance of the aluminum metal plate was observed.

  From the above results, it has been found that by using a ceramic joined body obtained by joining a larger number of thinner first sheet-like members, higher shock absorption is exhibited.

  The shock absorbing member of the present invention exhibits a high shock absorption equivalent to or higher than that of the conventional product, and can be made thinner, so that it is lighter than the conventional product and is suitable as a material for forming a protective device. is there. As an application example of the impact absorbing member of the present invention, it is possible to reliably reduce the impact that may be exerted on human bodies, vehicles, etc. from various high-speed flying bodies, while suppressing the burden on human bodies, vehicles, etc. And various protective products such as a robot arm that can be moved at high speed.

5, 10, 20: first sheet-like member 15, 25: ceramic joined body 30: third sheet-like member 40: fourth sheet-like member 50, 55, 60: shock absorbing member 65: joining layer 70: Receptive layer

Claims (6)

A plurality of first sheet-like members having a thickness of 0.1 to 1 mm made of ceramics containing 60% by mass or more of boron carbide;
A ceramic joined body that is disposed between adjacent first sheet-like members and has a joining layer that joins opposing joining surfaces of the adjacent first sheet-like members;
A plurality of the first sheet-like members are disposed so as to be laminated in the thickness direction,
The bonding layer is formed of an adhesive containing an organic resin,
The impact-absorbing member, wherein the bonding layer has a Young's modulus of 50 MPa or more and less than 3100 MPa.   The impact-absorbing member according to claim 1, wherein 2 to 1000 sheets of the first sheet-like member are laminated and arranged in the thickness direction.   The impact absorbing member according to claim 2, wherein the thickness of the first sheet-like member increases stepwise from the front surface side to the back surface side of the ceramic joined body. The impact-absorbing member according to any one of claims 1 to 3 , wherein the bonding layer has a thickness of 0.01 to 1 mm. The impact-absorbing member according to any one of claims 1 to 4 , further comprising a receiving layer that is disposed on a back surface side of the ceramic bonded body and receives a fragment generated at the time of breakage. Wherein the adhesive, epoxy resin adhesive, cyanoacrylate adhesive, modified silicone-based adhesive, and any one of claims 1 to 5, at least one selected from the group consisting of a polyurethane resin-based adhesive The impact-absorbing member described in 1.

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