JP2008095708A - Impact reducing member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impact reducing member which can be formed into a thin shape (particularly, a thickness of 1 cm or less), in which a conventional buckling structure hardly absorbs energy, and an impact reducing part using the same. <P>SOLUTION: The impact reducing member is composed of a composition material including a liquid, a fiber having a diameter of 15 μm or more and a length of 500 μm or more, and particles, the particles having a needle shape having an aspect ratio of 5 or more. The impact reducing member includes the impact reducing member sealed therein. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an impact reducing member that is installed in, for example, an automobile and protects an occupant or pedestrian who receives an impact at the time of a collision.

  2. Description of the Related Art Conventionally, there is known a device that reduces energy at the time of a secondary collision such as steering and interior materials by an inertial force applied to an occupant after an automobile collision. For example, in the invention related to the back surface rib structure of the interior pillar described in Patent Document 1, a structure capable of reducing the head obstruction value (HIC value) by providing a structure excellent in energy absorption on the back surface of the resin pillar and making the stroke short. Proposed.

As for pedestrian protection, for example, in the invention relating to the back surface of the engine hood described in Patent Document 2, a structure is proposed in which a buckling structure is provided at the part and the head obstacle value can be reduced as in Patent Document 1.
JP-A-9-220985 JP-A-7-285464

  However, in either case of Patent Documents 1 and 2, energy absorption with a shorter stroke than the conventional structures described in these documents is high, but because it is energy absorption by a buckling structure, it is suitable for installation in interior materials. In that case, the thickness of several centimeters (about 5 cm) is necessary, and the appearance is poor. In the installation of the engine hood, it is extremely difficult to apply to a bumper that a pedestrian contacts in the initial stage of the collision. There is a drawback. These disadvantages are due to the fact that energy absorption at a thickness of 1 cm or less that does not affect the layout cannot be obtained with these buckling structures.

  Accordingly, an object of the present invention is to provide an impact reducing member that can be formed thin (particularly, a thickness of 1 cm or less) that is difficult to absorb energy by a conventional buckling structure, and an impact reducing component using the same. is there.

  In the present invention, since the conventional structures described in Patent Documents 1 and 2 are buckling structures, the hardness change is small, and the hardness increases rapidly due to bottoming according to the buckling. As a result, the inventors have invented a material that gradually becomes soft while reducing the collision speed by becoming hard when the strain speed at the time of collision is high, and has solved the conventional drawbacks.

  That is, an object of the present invention is a composite material composed of a liquid, fibers and particles having a diameter of 15 μm or more and a length of 500 μm or more, wherein the particles have an acicular shape having an aspect ratio of 5 or more. This can be achieved by the impact reducing member.

  Another object of the present invention can be achieved by a pedestrian or occupant impact reduction component characterized in that a composite in which the impact reduction member is sealed is installed in the interior and / or exterior of an automobile. .

  According to the shock absorbing member of the present invention, the agglomeration property of acicular particles when the strain rate at the time of collision is high (that is, the acicular particles are agglomerated and concentrated when strain is applied, and dilatancy (strain rate curability). It is possible to provide an unprecedented thin shock-absorbing member using As a result, it is possible to provide a safe shock-absorbing component that can absorb the energy of collision, reduce injury to occupants and pedestrians, has a high degree of freedom in shape, and does not adversely affect the design.

  In addition, in the shock absorbing member of the present invention and the shock absorbing component using the same, the material gradually softens while reducing the collision speed by becoming hard when the strain speed at the time of collision is high. By using (composite material), the point which can provide said hardness change, without requiring an external signal especially can also be mentioned as an advantage. This means that sensors and actuators are not required, which is not only economically superior, but also extremely advantageous in terms of space efficiency and flexibility in selecting an installation site.

The impact reducing member of the present invention is a composite material composed of a liquid, fibers and particles having a diameter of 15 μm or more and a length of 500 μm or more, wherein the particles have an acicular shape having an aspect ratio of 5 or more. To do. As a result, when the strain rate at the time of collision is high, the acicular shaped particles aggregate and increase in concentration when strain is applied, and dilatancy (strain rate curability) can be expressed, and the energy of the collision is reduced while decelerating the impact. Can absorb and gently bottom out. Therefore, injuries to occupants and pedestrians can be reduced, such as greatly reducing the head injury value. In particular, needle-shaped particles with an aspect ratio of 5 or more have a chain structure even during normal (non-collision) time, so the strain rate at the time of collision is high.
Further, since the impact reducing member of the present invention is a liquid material, it can be used by being enclosed in a container of any shape, and has a high degree of freedom in shape, and is a thin sheet container (particularly a resin having a high degree of freedom in shape). Dilatancy (strain rate hardening) can be used even in thin impact-reducing parts (especially with a thickness of 1 cm or less) that are difficult to absorb energy with such a conventional buckling structure. (See examples below), and can be applied along the shape of the inside of the interior pillar and the back side of the engine hood (bonnet) without adversely affecting the design. In addition, it is excellent in that it can be applied along the shape of the inside of a bumper, which has been difficult to apply.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention should be determined based on the description of the scope of claims, and is not limited to the following embodiments. .

  FIG. 1 is a drawing schematically showing a state of change when an impact reducing member of the present invention receives stress from the outside due to a collision or the like. Among these, FIG. 1A is a drawing schematically showing an ordinary state of the impact reducing member of the present invention (a state in which no stress is applied from the outside due to a collision or the like), and FIG. 1B is an impact reducing member of the present invention. FIG. 6 is a drawing schematically showing a state when stress is applied from the outside due to a collision or the like.

  As shown in FIGS. 1A and 1B, the impact reducing member 11 of the present invention is a composite material composed of a liquid 12, fibers 13 having a diameter of 15 μm or more and a length of 500 μm or more, and particles 14, and the particles 14 have an aspect ratio. It is a needle-shaped particle having a ratio of 5 or more. Furthermore, an appropriate amount of spherical particles having an aspect ratio of less than 5 (not shown, hereinafter also referred to as particles 14 ′) may be included within a range that does not impair the effects of the present invention. FIG. 1 shows how the hardness changes when needle-shaped particles 14 having an aspect ratio of 5 or more are used.

  As shown in FIG. 1A, the needle-shaped particles 14 are normally present in a colloidal state dispersed in the liquid 12, and the fibers 13 are also present in the liquid 12. As shown in FIG. 1B, the impact reducing member 11 of the present invention has a needle-like shape that has been dispersed in a colloidal state due to being given a high strain rate in the compression direction by receiving stress from the outside due to collision or the like. The particles 14 aggregate to take a chain structure. In the present invention, since the fibers 13 are present in the vicinity of the particles 14, the needle-shaped particles 14 are formed along the fibers 13, in particular, in the major axis direction of the fibers 13 where the surface energy is stable (the fibers 13 are woven or non-woven fabrics). In the case of the form, the particles are aggregated along the in-plane direction of the cloth surface (the needle-shaped particles 14 are aggregated so as to overlap in the longitudinal direction of the particles as shown in FIG. 1B), or the fibers 13 are the end points. And has the property of aggregating. By such aggregation of the particles 14, the concentration can be increased and dilatancy (strain rate curability) can be expressed (this changes the compression elastic modulus or viscosity of the impact reducing member 11). Therefore, the impact reducing member 11 becomes soft when the strain rate at the time of collision is high (becomes changed to the state shown in FIG. 1B), and gradually becomes soft while reducing the collision speed (see FIG. 1A). (Recovers to the state shown). In the present invention, by using the impact reducing member 11 made of the composite material having the above-described characteristics, the above-described change in hardness can be provided without requiring an external signal.

  1C and 1D show an embodiment in which spherical particles 14 ′ are dispersed together with needle-like particles 14 in the liquid 12. Also in this case, the same mechanism as described in FIGS. 1A and 1B can be obtained. That is, as shown in FIG. 1C, the needle-shaped particles 14 and the spherical particles 14 ′ are normally present in a colloidal state dispersed in the liquid 12, and the fibers 13 are also present in the liquid 12. Yes. As shown in FIG. 1D, the impact reducing member 11 is subjected to stress from the outside due to a collision or the like, and is given a high strain rate in the compression direction, whereby the needle-like particles 14 dispersed in a colloidal state. And spherical-shaped particle | grains 14 'aggregate and take a chain structure. In the present invention, since the fibers 13 are present in the vicinity of the particles 14 and 14 ′, the acicular particles 14 and the spherical particles 14 ′ are arranged along the fibers 13, in particular, the long axis of the fibers 13 whose surface energy is stable. Aggregated along the direction (in the in-plane direction of the cloth surface when the fibers 13 are woven or non-woven), the needle-shaped particles 14 are arranged so as to overlap in the major axis direction of the particles as shown in FIG. 1D. Aggregates and aggregates such that spherical particles 14 ′ enter between these particles or in the gaps between them, or aggregates with the fiber 13 as an end point. Due to the aggregation of the particles 14 and 14 ′, the concentration can be increased and dilatancy (strain rate curability) can be expressed (thereby changing the compression modulus or viscosity of the impact reducing member 11). ). Therefore, the impact reducing member 11 becomes softer while reducing the collision speed by becoming hard (changes to the state shown in FIG. 1D) when the strain speed at the time of collision is high (shown in FIG. 1C). Characteristics). Also in this embodiment, by using the impact reducing member 11 made of the composite material having the above-described characteristics, the above-described change in hardness can be provided without requiring an external signal.

  Hereinafter, the present invention will be described in more detail for each component.

(1) Particle 14
(I) Particle shape (aspect ratio and particle (cross-sectional) diameter)
The particles 14 constituting the composite material used for the impact reducing member of the present invention have an acicular shape with an aspect ratio of 5 or more, preferably 5 to 100, more preferably 20 to 100, and particularly preferably 50 to 100. It is a feature.

Here, the aspect ratio of the particle and the (cross-sectional) diameter of the particle mean an average value of 100 particles observed with a transmission electron microscope. Aspect ratio, as shown in FIG. 8A, the maximum value of the major axis of the particles (major axis) and (L _1), the average of the major axis L _a and minor axis L _b of the cross section of the minor axis (short axis direction) determined as a value _{(L 2 = (L a +} L b) / 2) and the ratio of _(L 1 / L _{2) (where,} a _{L a} ≧ _{L b,} the cross-sectional shape in the case of _L a = L _b Circular). Next, (cross section) The diameter of a particle means the average value of the major axis L _a and minor axis L _b of the cross section of the minor axis of the particles (minor axis direction) and (L _2). Even when the particles have a hollow shape or a sea-island shape, the aspect ratio of the particles and the (cross-sectional) diameter of the particles can be obtained as shown in FIG. Note that spherical particles having an aspect ratio of less than 5 can be measured by the same method. As the average particle diameter of spherical particles having an aspect ratio of less than 5 described later, the average value (L ₁ + L ₂ ) / 2 of L ₁ and L ₂ of the particles used for calculating the aspect ratio is used (here L ₁ ≧ L ₂ and in the case of spherical particles, L ₁ = L ₂ (= L _a = L _b ).)

Moreover, the diameter of the fiber 13 mentioned later and the length of a fiber mean the average value of five fibers observed with the scanning electron microscope. As shown in FIG. 8C, the fiber (cross-section) diameter is the average value (L ₄ = (L _c + L _d ) / 2) of the major axis L _c and the minor axis L _d of the cross section of the fiber (minor axis direction) (Where L _c ≧ L _d and when L _c = L _d , the cross-sectional shape is circular). The length of the fiber means the maximum value (L ₃ ) of the major axis (major axis length) of the fiber. Even when the fiber has a hollow shape or a sea-island shape, the fiber diameter and fiber length can be determined as shown in FIG.

  When the particles 14 are not spheres (spherical shapes) but are needle-shaped shapes having an aspect ratio of 5 or more, spheres (spherical shapes) 14 ′ having an aspect ratio of less than 5, particularly 3 or less are used. Compared with the above, even when the particle concentration is low, the particles can be agglomerated by giving a high strain rate. This is because, if the particles are acicular, the surface energy is larger than that of the spherical particles 14 '. As a result, in an automobile or the like using an impact reducing member, it is possible to absorb collision energy with an unprecedented thin impact reducing component structure, and to effectively reduce injuries (head injury values) of passengers and pedestrians. . The higher the aspect ratio of the particles 14, the easier it is to aggregate, and the smaller the cross-sectional diameter of the particles 14, the more likely to aggregate. According to the study by the present inventors, such agglomeration can suitably occur when the cross-sectional diameter of the particles 14 is 1000 nm or less. If the cross-sectional diameter of the needle-shaped particles 14 is 1000 nm or less, the particles 14 are aggregated within a range of 10 to 10,000 (1 / s), which is a strain rate experienced by an occupant or a pedestrian in an automobile collision. It is because it can cause. From this viewpoint, the upper limit of the cross-sectional diameter of the particles 14 is preferably 50 nm or less, and more preferably 20 nm or less. On the other hand, the lower limit of the cross-sectional diameter of the needle-shaped particles 14 is required to be 5 nm or more. If the cross-sectional diameter of the needle-shaped particles 14 is 5 nm or more, the strain rate is high in the compression direction in advance (= as normal, as shown in FIG. In such a state, the particles can be stably dispersed in the liquid without being agglomerated in a state in which the agglomerated state is not given), and the agglomerated state changes according to the strain rate intended by the present invention. In addition, the present inventors synthesized needle-shaped particles 14 having an aspect ratio of 5 or more, but needle-shaped particles having a cross-sectional diameter of less than 5 nm are extremely difficult to manufacture and are substantially difficult to manufacture. . From this viewpoint, the lower limit of the cross-sectional diameter of the needle-shaped particles 14 is preferably 5 nm or more. From the above, the cross-sectional diameter of the particles 14 is in the range of 5 to 1000 nm, preferably 5 to 50 nm, more preferably 5 to 20 nm.

(Ii) Particle Concentration The concentration of the particle 14 depends on the diameter (L ₂ ) and the aspect ratio (L ₁ / L ₂ ) of the particle, but the particle 14 is within a strain rate of 10 to 10,000 (1 / s). In order to cause aggregation, it is preferable that the particle concentration, particle diameter, and aspect ratio generally satisfy the following relational expression. From the viewpoint of dispersibility in the liquid 12, which will be described later, the concentration of the particles 14 is preferably 40 vol% or less from the viewpoint of dispersion stability. When the concentration of the particles 14 exceeds 40 vol%, the needle-shaped particles may be aggregated at a normal time (the state shown in FIG. 1A). About the minimum of the density | concentration of the particle | grains 14, 5 vol% is the minimum amount from the experiment which the present inventors conducted. Aggregation of the particles 14 tends to occur according to the following relational expression, but when considering the degree of aggregation according to the particle concentration, 5 vol% is the lower limit. Therefore, the concentration of the particles 14 is 5 to 40 vol%, preferably 10 to 40 vol%, more preferably 10 to 20 vol% with respect to the volume of the composite material composed of the liquid 12, the fibers 13, and the particles 14. .

  The concentration of the particles defined above is the concentration of acicular particles having an aspect ratio of 5 or more. However, in the impact reducing member of the present invention, as described later, within the range not further impairing the function and effect of the present invention. Alternatively, particles (14 + 14 ′) obtained by mixing an appropriate amount of spherical particles 14 ′ having an aspect ratio of less than 5 may be used. The concentration of the particles (14 + 14 ′) in this case also preferably satisfies the following relational expression. Considering the dispersion stability in the liquid and the degree of aggregation according to the particle concentration, the liquid 12, the fiber 13, and It is desirable that the volume is 5 to 40 vol%, preferably 10 to 40 vol%, more preferably 10 to 20 vol, with respect to the volume of the composite material composed of the particles 14 and the particles 14 ′. In this case, for the aspect ratio, the particle concentration, and the particle diameter in the following relational expressions, values measured for the entire particle (mixture) are used.

(Iii) Particle Material The material of the particle 14 is an unprecedented thin structure using an impact reducing member. When the strain rate at the time of collision is high, the particle 14 becomes hard and gradually softens while reducing the collision speed. There is no particular limitation as long as the particles are made of a material suitable for the above. For example, particles of alumina (boehmite (γ alumina), α alumina, etc.), silica, titania, zirconia, calcia (calcium oxide), or the like can be used. These may be used alone or in combination of two or more. In order to obtain the above particle diameter and aspect ratio economically advantageously, alumina particles are most suitable. The present inventors use an alumina raw material at various temperatures and raw material concentrations, and are defined in the present invention as a needle-shaped alumina having a particle diameter (short axis diameter) of 5 to 1000 nm and an aspect ratio of 5 or more. Particles could be obtained. The alumina particles produced by the present inventors in the examples are boehmite (γ alumina monohydrate) from the results of X-ray diffraction, but α-alumina needle-shaped particles can also be produced as described later. It is. Specifically, it will be described in the section of particle production method described later.

(Iv) Method for Producing Particles The method for producing the particles 14 is not particularly limited, and a conventionally known production method can be used. For example, the present inventors use an alumina raw material at various temperatures and raw material concentrations, and produce a needle-shaped product having a particle diameter of 5 to 1000 nm and an aspect ratio of 5 or more as defined in the present invention. Can be used.

Specifically, for example, (1) the short axis length is 1 to 10 nm, the long axis length is 20 to 400 nm, and the aspect ratio is 5 to 80 as in the manufacturing method described in JP-A-2006-62905. A method for producing alumina particles represented by the general formula Al ₂ O ₃ .nH ₂ O (where n = 1 in the general formula and the alumina particles are boehmite (γ-alumina monohydrate)). Furthermore, it is also a production method suitable for the alumina particles having a hollow portion inside.) An alkaline aqueous solution is added to an aluminum metal salt aqueous solution, and the resulting reaction mixture is mixed with A step of generating a gel substance of aluminum hydroxide, a step of subjecting the reaction mixture containing the gel substance to a first heat treatment at a first temperature not lower than room temperature, and after the first heat treatment, the gel Matter Applying the second heat treatment to the reaction mixture containing the second heat treatment at a second temperature higher than the first temperature in the first heat treatment, and the reaction containing the gel substance after the second heat treatment. Subjecting the mixture to a third heat treatment at a third temperature lower than the second temperature in the second heat treatment; and after the third heat treatment, the reaction mixture containing the gel-like substance is brought to room temperature or higher And a step of performing a fourth heat treatment at the fourth temperature. The method can be produced by a method for producing alumina particles.

  In this case, the molar ratio of the aluminum metal salt aqueous solution concentration and the alkali aqueous solution concentration is preferably 1: 2 to 4.

  The concentration of the aqueous aluminum metal salt solution is desirably 1.0 M to 3.0 M, and the concentration of the alkaline aqueous solution is desirably 4.0 M to 10.0 M.

  Furthermore, it is desirable to change the form of the boehmite particles by changing the pH of the reaction mixture.

  The first temperature in the first heat treatment is preferably in the temperature range of room temperature to 140 ° C.

  Furthermore, it is desirable that the second temperature in the second heat treatment is in a temperature range of 140 ° C. to 250 ° C.

  Furthermore, it is desirable that the third temperature in the third heat treatment is in a temperature range of 130 ° C. or lower.

  In addition, it is preferable that a cooling time from the second temperature in the second heat treatment to the third temperature in the third heat treatment is within 10 minutes.

  Furthermore, it is desirable that the fourth temperature in the fourth heat treatment is in a temperature range of 100 ° C. to 180 ° C.

Alternatively, (2) as in other manufacturing methods described in JP-A-2006-62905, the minor axis length is 1 to 10 nm, the major axis length is 20 to 400 nm, the aspect ratio is 5 to 80, A method for producing alumina particles represented by the formula Al ₂ O ₃ .nH ₂ O (in the general formula, n = 0, which is suitable for a production method in which the alumina particles are α-alumina. Furthermore, the alumina particles It is also a production method suitable for those having a hollow portion inside.) An alkaline aqueous solution is added to an aqueous aluminum metal salt solution, and an aluminum hydroxide gel-like substance is formed in the resulting reaction mixture. A step of subjecting the reaction mixture containing the gel-like substance to a first heat treatment at a first temperature equal to or higher than room temperature; and after the first heat treatment, the reaction mixture containing the gel-like substance is added to the first mixture. A step of performing a second heat treatment at a second temperature higher than the first temperature in the first heat treatment, and after the second heat treatment, the reaction mixture containing the gel substance is added to the second heat treatment. Performing a third heat treatment at a third temperature lower than the second temperature; and after the third heat treatment, the reaction mixture containing the gel-like substance is treated with a fourth temperature at a fourth temperature equal to or higher than room temperature. And a step of subjecting the boehmite particles obtained through the fourth heat treatment to a firing treatment, and a method of producing alumina particles.

  In this case, the molar ratio of the aluminum metal salt aqueous solution concentration and the alkaline aqueous solution concentration is preferably 1: 2-4.

  The concentration of the aqueous aluminum metal salt solution is desirably 1.0 M to 3.0 M, and the concentration of the alkaline aqueous solution is desirably 4.0 M to 10.0 M.

  Furthermore, it is desirable to change the form of the boehmite particles by changing the pH of the reaction mixture.

  The first temperature in the first heat treatment is preferably in the temperature range of room temperature to 140 ° C.

  Furthermore, it is desirable that the second temperature in the second heat treatment is in a temperature range of 140 ° C. to 250 ° C.

  Furthermore, it is desirable that the third temperature in the third heat treatment is in a temperature range of 130 ° C. or lower.

  In addition, it is preferable that a cooling time from the second temperature in the second heat treatment to the third temperature in the third heat treatment is within 10 minutes.

  Furthermore, it is desirable that the fourth temperature in the fourth heat treatment is in a temperature range of 100 ° C. to 180 ° C.

  The alumina particles produced by the present inventors in the examples are boehmite (γ alumina monohydrate) from the results of X-ray diffraction, but α alumina can also be produced as described above.

  Furthermore, it can also be manufactured by (3) the manufacturing method described in Japanese Patent Application No. 2004-259933.

  In addition, particles made of other materials (materials other than alumina) having a needle-like shape with an aspect ratio of 5 or more specified in the present invention can be obtained by a conventionally known method.

(V) Spherical particles 14 ′
The particles 14 are needle-like particles having an aspect ratio of 5 or more, but may further contain an appropriate amount of spherical particles 14 ′ having an aspect ratio of less than 5 within a range not impairing the effects of the present invention. This is because, in order to obtain particles at a low cost, it is an effective means to increase not only particles having a high aspect ratio but also particles having a low aspect ratio that can be produced or obtained at low cost in combination. For example, in the case of generally known silica particles, the aspect ratio is reduced due to the shape close to a sphere, but when the amount of particles is increased, inexpensive silica particles are used to provide members at low cost. It becomes possible.

  The shape of the spherical particles 14 ′ is less than 5, preferably 1 or less, more preferably 1 to 2 in aspect ratio.

  The average particle diameter of the spherical particles 14 ′ is 5 to 1000 nm, preferably 5 to 50 nm, more preferably 5 to 20 nm. Regarding the average particle diameter of the spherical particles 14 ′, the same reason as the above-mentioned needle-shaped particle diameter applies, and the smaller the average particle diameter of the spherical particles 14 ′, the more likely to aggregate. . Such agglomeration requires that the average particle diameter of the spherically shaped particles 14 ′ is 1000 nm or less. When the average particle diameter of the spherical particles 14 'exceeds 1000 nm, the aggregation is extremely difficult to occur within a range of 10 to 10,000 (1 / s) which is a strain rate experienced by an occupant or a pedestrian in an automobile collision. is there. On the other hand, the lower limit is required to be 5 nm or more. Particles 14 ′ having an average particle size of less than 5 nm are in advance (= as shown in FIG. 1C, in a normal state, and are not given a high strain rate in the compression direction due to external stress due to collision or the like. ) Is strongly agglomerated and stable dispersion cannot be achieved, which may make it difficult to obtain a mechanism that the agglomerated state changes according to the strain rate intended by the present invention. The spherical particles 14 ′ having an average particle size of less than 5 nm are difficult to manufacture and are also difficult to manufacture. Note that the method for measuring the average particle diameter of the spherical particles 14 ′ here has already been described in the section of the needle-shaped particles 14 having an aspect ratio of 5 or more, so the description thereof is omitted here. .

  The material of the spherical particle 14 ′ is not particularly limited, but it is preferable that the spherical particle 14 ′ is manufactured or available at a low cost as described above. From this viewpoint, silica, calcium carbonate, and the like can be given. However, it is not limited to these. These may be used alone or in combination of two or more.

The ratio (M ₁ : M ₂ ) between the blending amount (M ₁ ) of the needle-shaped particles 14 having an aspect ratio of 5 or more and the blending amount (M ₂ ) of the spherical particles 14 ′ having an aspect ratio of less than 5 is In the range satisfying the concentration of the particles (14 + 14 ′) defined above, M ₁ : M ₂ = 100: 0 to 100, preferably 100: 25 to 100, more preferably 100: 25 to 50 is satisfied. It is desirable to do. On the other hand, if M ₂ is 100 parts by mass or less with respect to 100 parts by mass of M _{1, the} amount of acicular particles 14 having a larger surface energy than spherical particles 14 ′ can be kept relatively high. In addition to being excellent in that aggregation at a low particle concentration, which is one of the operational purposes of the present invention, can be effectively expressed, the particle concentration can be lowered, so that the fluid 12, the fiber 13, the particle 14 and the particle 14 can be reduced. The density of composite materials composed of 'can be lowered. The lower limit of M ₂ with respect to 100 parts by mass of M ₁ is not particularly limited, but if it is 25 parts by mass or more, the blending amount of the spherical particles 14 ′ can be relatively increased, so that it is inexpensive. It is excellent in that particles can be obtained.

(2) Fiber 13
Next, the fiber 13 will be described.

(I) Diameter of the fiber 13 (L ₄ )
The fiber 13 serves to assist agglomeration of particles (in the case where the needle-shaped particles 14 and further the spherical particles 14 ′ are mixed, the spherical particles 14 ′ are included), and the impact reducing member 11. Since it is responsible for its own shape stability, the diameter of the fiber 13 is an important parameter. If a firm one is required, the fiber diameter should be large, and conversely if a flexible one is needed, one with a small fiber diameter is preferred. However, if the fiber diameter is less than 15 μm, the cohesive force of the particles 14, 14 ′ tends to decrease, so a lower limit of 15 μm is necessary. From this viewpoint, the lower limit of the diameter of the fiber 13 is preferably 20 μm or more, more preferably 25 μm or more. The upper limit of the diameter of the fiber 13 is not particularly limited, but the number is remarkably reduced and aggregation of the particles 14 and 14 ′ hardly occurs, so the upper limit is substantially about 1 mm. The upper limit of the diameter of the fiber 13 is preferably 500 μm or less, more preferably 200 μm or less.

(Ii) Length of the fiber 13 (L ₃ )
The length of the fiber 13 needs to be 500 μm or more. This is because the particles 14 and 14 ′ gather on the fiber 13, and if the fiber 13 is short, the aggregates of the particles 14 and 14 ′ become small and the cohesive force decreases. Further, if the fibers 13 are short, it is difficult to stably disperse in the liquid 12 at normal times (the state shown in FIG. 1A), and there is a possibility that the fibers 13 may precipitate. Since the particles 14 and 14 ′ are aggregated using the fiber 13 as a column, the diameter of the above-described fiber 13 is 15 μm or more, and 500 μm or more is required. More preferably, the length of the fiber 13 is 10 mm or more, and more preferably 1000 mm or more. The upper limit of the length of the fiber 13 is arbitrary. For example, there is no limitation as in the case of a woven fabric or a non-woven fabric described later. In other words, in the case of an impact reduction part in which a composite in which the impact reduction member is sealed is installed in the interior and / or exterior of an automobile, a woven or non-woven fabric cut into a shape that covers the entire impact reduction part Although it is desirable to use a fiber, it is not restricted to these at all. There is no upper limit on the length even when the fibers (in the form of long fibers or short fibers) are dispersed in the liquid instead of the woven fabric or the non-woven fabric.

(Iii) Material (material) of fiber 13
As a result of examinations by the present inventors with various fibers, it has been found that the influence of the fibers 13 on the aggregation of the particles 14 and 14 ′ is extremely small compared to the values such as the particle concentration.

  Therefore, the material (material) of the fiber 13 is not particularly limited, and examples thereof include organic fibers such as aramid fiber, nylon (registered trademark) fiber, polyester fiber, and polyurethane fiber, glass fiber, ceramic fiber, metal fiber, and carbon fiber. Inorganic fibers such as (carbon fiber) can be used. These may be used alone or in combination of two or more. The penetrability of the impact reducing member 11 is greatly affected by the fiber material and the weaving form. Therefore, it is desirable to select a fiber material with high strength, particularly when it is desired to increase the penetration resistance. When it is desired to improve penetration resistance, it is preferable to use an aramid fiber. This is because when the aramid fiber and the nylon fiber are used for the fibers 13, the aramid fibers tend to be slightly superior in penetration resistance. Therefore, in the present invention, characteristics such as hardness change characteristics (= mechanism characteristics that the aggregation state changes according to the strain rate intended by the present invention) and penetration resistance using the various fibers described above are measured in advance. Thus, it is possible to suitably select a fiber according to the required characteristics. However, the penetration resistance is not particularly limited here because the required characteristics vary depending on the part to be installed.

(Iv) Form of the fiber 13 The form of the fiber 13 is not particularly limited, and the fiber may be used in the form of a single fiber such as a long fiber or a short fiber, or such a fiber is knitted. Form, woven form, knitted, laminated form of woven fabric, non-woven fabric (fiber and fiber are entangled using appropriate heat and adhesives, physical or chemical means such as high-pressure water flow, or mechanical means Alternatively, a form of a cloth-like sheet formed by bonding or bonding may be used. These forms may be used in one form, or two or more forms may be used in combination. The form of the fiber 13 is preferably a woven fabric or a non-woven fabric. When used in the form of a woven fabric or a non-woven fabric, it is easier to handle than a single fiber and is easy to mix (especially, it is easy to be present on one side of a composite enclosing an impact reducing member). In the composite step (mixing and dispersing step), the fibers 13 can be easily mixed. Moreover, when using with the form of a woven fabric and a nonwoven fabric, the fiber 13 will exist in one surface (entire surface) of the installation surface of the impact reduction component of a vehicle interior or exterior, for example (refer FIG. 5A mentioned later). The penetration resistance is most advantageous and contributes to increasing the breaking strength. In particular, when it is installed on a door part of an automobile, the advantage can be enjoyed.

(V) Mixing ratio of fiber 13 The mixing ratio of fiber 13 is 3 to 30 vol%, preferably 10 to 30 vol%, with respect to the volume of the composite material composed of liquid 12, fiber 13, and particles 14 and 14 '. It is. When the mixing ratio of the fibers 13 is 10 vol% or more, the fibers 13 are present in the vicinity of the particles 14, 14 ′ when a high strain rate is applied even when the low concentration particles 14, 14 ′ are used. Therefore, the particles 14 (14 ′) can be aggregated along the fibers 13 or aggregated with the fibers 13 as end points to form a chain structure. As a result, it is possible to obtain a mechanism in which the aggregation state changes according to the strain rate intended by the present invention. On the other hand, when the mixing ratio of the fibers 13 is 30 vol% or less, the fibers 13 are in the vicinity of the low concentration particles 14, 14 ′ when a high strain rate is applied even if the lower concentration particles 14, 14 ′ are used. Therefore, the low concentration of the particles 14 (14 ′) can be effectively aggregated along the fibers 13 or aggregated with the fibers 13 as end points to form a chain structure. As a result, it is possible to obtain a mechanism in which the aggregation state changes according to the strain rate intended by the present invention. When the mixing ratio of the fibers 13 exceeds 30 vol%, the concentration of the particles is relatively lowered. Therefore, aggregation is performed according to the strain rate, the concentration is increased, and dilatancy (strain rate curability) is expressed. It may be difficult to obtain a mechanism for changing the state. Further, when the mixing ratio of the fibers 13 is 3 vol% or more, preferably 5 vol% or more, it is preferable that there is no fear that the amount of particles for expressing such a chain structure has to be increased.

(3) Liquid 12
Next, the liquid 12 will be described.

(I) Liquid material (material)
It is essential that the liquid 12 does not deteriorate or transform with respect to the environmental temperature. Moreover, what can disperse | distribute particle | grains 14 and 14 'stably is desirable. Regarding the dispersibility of the particles, if necessary, an appropriate dispersion stabilizer (for example, p-toluenesulfonic acid) is added to the particles 14, 14 ′, and even single fibers (in the case of a woven fabric, Even if it is not particularly dispersed, it may be made to exist in the liquid as shown in FIG. 5A). For automotive applications, it is necessary to maintain these characteristics in the temperature range of -40 ° C to 90 ° C, although it depends on the part. From this point of view, it is desirable that the liquid 12 for use in automobiles does not change or transform in the temperature range of −40 ° C. to 90 ° C. From this point, water-based ones are difficult to use. Liquids such as ethanol, 2-butanone, tetrahydrofuran, cyclohexanone, and ethylene glycol are preferably used to stably disperse the particles such as the needle-shaped alumina particles 14 and the spherical silica particles 14 '. sell. These may be used alone or in combination of two or more. From the viewpoint of preventing fire and volatilization, ethylene glycol is most suitable.

(Ii) Means for improving dispersion stability of particles 14, 14 ′ in liquid 12 For the formulation of particles 14, 14 ′ for stabilizing dispersion in liquid 12, any existing method can be used. . For example, any of the above-described acicular alumina particles 14 and spherical silica particles 14 'has a hydroxyl group on the particle surface, and thus tends to be difficult to disperse in liquids other than water. . Therefore, as a prescription (surface treatment or surface modification method) for the particles 14 and 14 ′, treatment with an organic acid such as phosphoric acid, sulfonic acid or carboxylic acid, or hydrophobization with a silane coupling agent, a titanium coupling agent, or the like. By the treatment or the like, the dispersion can be sufficiently stabilized in an organic solvent (liquid 12) such as ethylene glycol. In addition, you may add dispersing agents (dispersion stabilizer), such as p-toluenesulfonic acid, as needed.

(4) Other additives In addition to the liquid, fiber, and particles, the composite material of the impact reducing member of the present invention may be oxidized if necessary as long as the effects of the present invention are not impaired. Inhibitors, heat stabilizers (eg, hindered phenols, hydroquinones, thioethers, phosphites and their substitutes), other additives, dispersants such as p-toluenesulfonic acid (dispersion stabilizers), water, etc. You may mix | blend and use an appropriate amount for an additive.

  Next, the impact reducing component for a pedestrian or passenger of the present invention is characterized in that a composite containing the impact reducing member of the present invention is installed in the interior and / or exterior of an automobile.

  The impact reducing component 22 of the present invention is a structure (encapsulated) in which a composite material (= impact reducing member 11) composed of the liquid 12, the particles 14, and the fibers 13 is encapsulated (enclosed) in an appropriate enclosure 21 described above. = Composite) can be used in the interior and exterior of automobiles to provide impact reduction parts (such as automobile interior pillars and exterior bumper hoods) that can reduce obstacles to passengers and pedestrians.

(I) Material of Encapsulating Container 21 The material (packaging material) of the enclosing container 21 used for enclosing the composite material (= impact reducing member 11) may be appropriately determined according to the purpose of use. A resin sheet or container such as polyester or polyurethane, a metal or resin multilayer sheet (laminated sheet), or a metal container such as aluminum can be used. These are those that quickly and easily deform so that the impact-reducing member of the contents can agglomerate and increase the concentration of the needle-shaped particles by applying strain and develop dilatancy (strain rate curability) at the time of collision. Must be used. Preferably, it is desirable to use a material that is easy to obtain a degree of freedom of shape, and polyester, polyurethane, and the like can be suitably used.

(Ii) Thickness of Encapsulating Container 21 The thickness of the enclosing container 21 is difficult to define uniquely because the strength and ease of deformation differ depending on the type of material used. The optimum thickness may be determined through experiments as shown. In particular, since it is desirable that the thickness of the entire impact reducing member is 1 cm or less, the thickness of the enclosure is 4 to 8 mm, preferably 4 to 6 mm. If the thickness of the sealed container is 4 mm or more, the shape retainability is excellent, and the desired dilatancy (strain rate curability) is developed without causing the container to break and the contents to leak due to the impact applied at the time of collision. It is possible to maintain an appropriate strength to the extent that it can be produced. On the other hand, if the enclosure has a thickness of 1 cm or less, preferably 8 mm or less, particularly 6 mm or less, the thickness of the entire impact reducing member can be reduced, and various application destinations can be selected. In particular, when used for interior materials (for example, interior pillars), the dilatancy (strain rate curability) is developed in the impact reducing member in a short time of about 20 ms (time from the collision) when the airbag operates. It is excellent in that the hardness peak can be taken, the head injury value (HIC value) can be reduced, and the safety of the occupant can be ensured. Also, it is excellent in that a pedestrian can reduce damage to a human body represented by a head disorder value by having a hardness peak in a short time of about 20 ms after a collision.

(Iii) Shape of Enclosed Container 21 The shape of the enclosed container is not particularly limited, and may be appropriately determined according to the purpose of use. Therefore, for example, as shown in FIG. 5, sealed containers having the same thickness may be used, or sealed containers having an uneven shape or a curved shape may be used depending on the application site.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited to only the forms shown in the following examples.

  In addition, the absorbed energy in the following examples and comparative examples is a result measured by the following method, and the energy absorbed until the hitting core was stopped was measured.

<Measurement method of absorbed energy>
-Measured according to ASTM D3763 "Standard test method for high-speed puncture property of plastic".

・ Test conditions Strike core; φ1 / 2 inch Tip; R1 / 4 inch Load; 125N
Test temperature: 23 ° C
Initial strain rate: 2200 1 / s
Moreover, the shape, length, and cross section of the particle | grains and fiber in a following example and a comparative example are the results measured with the following analysis methods and analytical instruments.

<(A) Particle shape measurement method>
A sample (alumina particles or silica particles) was diluted with pure water (two-stage distilled water) and then applied for 15 minutes with an ultrasonic cleaner. Thereafter, a sample was applied to a hydrophilically treated carbon-coated collodion film on a copper mesh and dried to prepare an observation sample. An electron microscope image of the sample was taken at 120 KV, 70 mA, 100,000 times, and observed with a transmission electron microscope (TEM).

-Copper mesh for TEM: Micro grit 150-B mesh, carbon reinforced Oken Shoji Co., Ltd.-Transmission electron microscope: JEOLJEM-1200EXII JEOL Ltd. <(b) Particle length measurement method>
The photograph taken with the transmission electron microscope (TEM) in (a) above was taken in as electronic data with a commercially available scanner, and the length of the particles was measured using software for measuring the length on a commercially available personal computer. 100 particles were randomly selected and measured for both the short axis length (diameter or short axis diameter) and long axis length of the particles.

Software name: Scion Image for Windows (registered trademark) Scion corp.
<(C) Particle Cross Section Measurement Method>
Particles (alumina particles or silica particles) obtained by lyophilization were placed in an ethoxy resin, and the particles were embedded in the resin. The cured resin was sliced to a thickness of about 60 to 100 nm using an ultramicrotome at room temperature. Thereafter, a thin piece was attached to the TEM grid to prepare an observation sample. An electron microscope image of the sample was taken with a transmission electron microscope at 300 KV and 400,000 magnifications and observed.

-Epoxy resin: EPON 812 Oken Shoji Co., Ltd.-Ultra microtome: FC-S type microtome REICHERT company-Transmission electron microscope: H-9000 Hitachi, Ltd. <(d) Measurement method of fiber length and diameter>
Take a photograph of the dried sample with a scanning electron microscope, capture the obtained photograph as electronic data with a commercially available scanner, and measure the length and diameter of the fiber using software for measuring the length on a commercially available personal computer. It was supposed to be.

In addition, the needle-shaped alumina particles having an aspect ratio of 10 having a diameter (L ₂ ) of 10 nm and a length (L ₁ ) of 100 nm used in Examples 1 to 5 below were prepared by the following manufacturing method. did.

<Method for producing needle-shaped alumina particles>
In a Teflon beaker equipped with a mechanical stirrer, aluminum chloride hexahydrate (2.0 M, 40 ml, 25 ° C.) was placed, and maintained at 10 ° C. in a constant temperature bath, while stirring (700 rpm), sodium hydroxide (5.10 M) , 40 ml, 25 ° C.) was added dropwise over about 6 minutes. Stirring was continued for another 10 minutes after the completion of dropping, and the pH of the solution was measured after the stirring was completed (pH = 7.08). The solution was replaced with an autoclave equipped with a Teflon liner and sealed, and aged in an oven at 120 ° C. for 24 hours (first heat treatment). After completion of the first heat treatment, the autoclave was transferred to an oil bath and heated at 180 ° C. for 30 minutes (second heat treatment). After completion of the second heat treatment, the autoclave was put into running water and rapidly cooled (about 10 ° C.) (third heat treatment). After completion of the third heat treatment, the autoclave was again placed in an oven and heated at 150 ° C. for one day (fourth heat treatment).

  Thereafter, the autoclave is cooled with running water, and the supernatant is removed by centrifugation (30000 rpm, 30 min), followed by washing with centrifugal water three times and a water methanol mixed solution (volume ratio water: methanol, 0.5: 9.5) once with centrifugal washing. went. Then, colorless crystals were obtained by drying using a freeze dryer. This colorless crystal was found to be boehmite as a result of X-ray diffraction. Further, when the size of the particles was examined using TEM, it was found that the particles had a needle shape with a major axis length of 100 nm, a minor axis length (diameter) of 10 nm, and an aspect ratio of about 10.

(Example 1)
A bag-like polyester sheet 21 (outer shape 10 cm × 10 cm) having a thickness of 1 mm shown in FIG. 2 was filled with 160 cm ³ of a mixture of the following liquid 12, fiber 13 and particles 14 (composite material = impact buffer member 11). As shown in FIGS. 3 and 4, a crimping margin (crimped portion) 23 having a total circumference of 5 mm was taken and sealed to produce an enclosure (composite = impact reducing component) 22. The thickness (H) of the enclosure 22 in FIG. 4 is about 20 mm.

Liquid 12; ethylene glycol fiber 13; glass fiber, diameter (L ₄ ) 15 μm, length (L ₃ ) 500 μm
Particle 14; Acicular alumina particles having a diameter (L ₂ ) of 10 nm and a length (L ₁ ) of 100 nm and an aspect ratio of 10 Volume mixing ratio; Liquid 12: Fiber 13: Particle 14 = 90: 5: 5
As a result of measuring the energy absorbed until the strike core 41 stopped under the above measurement conditions and calculating the absorbed energy required for penetration, energy absorption of 460J was measured.

(Example 2)
An encapsulant (composite = impact reducing component) 22 was prepared in the same manner as in Example 1 except that the mixture (composite material = impact buffer member 11) was changed to the following, and the absorbed energy was measured.

Liquid 12; ethylene glycol fiber 13; glass fiber, diameter (L ₄ ) 15 μm, length (L ₃ ) 500 μm
Particle 14; Acicular alumina particles having an aspect ratio of 10 having a diameter (L ₂ ) of 10 nm and a length (L ₁ ) of 100 nm; volume mixing ratio; liquid 12: fiber 13: particle 14 = 80: 5: 15
As a result of measuring the energy absorbed until the hitting core 41 stopped under the above measurement conditions and calculating the absorbed energy required for penetration, the energy absorption of 420J was measured.

(Example 3)
An encapsulant (composite = impact reducing component) 22 was prepared in the same manner as in Example 1 except that the mixture (composite material = impact buffer member 11) was changed to the following, and the absorbed energy was measured.

Liquid 12; ethylene glycol fiber 13; glass fiber, diameter (L ₄ ) 15 μm, length (L ₃ ) 500 μm
Particle 14; Acicular-shaped alumina particles having a diameter (L ₂ ) of 10 nm and a length (L ₁ ) of 100 nm and an aspect ratio of 10 Volume mixing ratio; Liquid 12: Fiber 13: Particle 14 = 55: 5: 40
As a result of measuring the energy absorbed until the strike core 41 stopped under the above measurement conditions and calculating the absorbed energy required for penetration, the energy absorption of 660 J was measured.

Example 4
An encapsulant (composite = impact reducing component) 22 was prepared in the same manner as in Example 1 except that the mixture (composite material = impact buffer member 11) was changed to the following, and the absorbed energy was measured.

Liquid 12; ethylene glycol fiber 13; woven fabric form using nylon fiber; fiber diameter (L ₄ ) 130 μm, fiber length (L ₃ ) (= length of one side of woven fabric) 90 mm, Thickness (see symbol h in FIG. 5B) 270 μm, distance between yarns of woven fabric (= between warp yarns 13a to weft yarn 13b; see symbol d in FIG. 5B) 155 μm, porosity of woven fabric 30%
Particle 14; Acicular alumina particles having a diameter (L ₂ ) of 10 nm and a length (L ₁ ) of 100 nm and an aspect ratio of 10 Volume mixing ratio; Liquid 12: Fiber 13: Particle 14 = 70: 5: 25
In this example, two woven fabric fibers 13 using nylon fibers were used as shown in FIG. 5A. The size of the fiber 13 in the form of a woven fabric using the nylon fiber corresponds to the size in the enclosure (composite = impact reducing component) 22, that is, the length 90 mm × width 90 mm × thickness 270 μm. Was used. Also in this example, the bag-shaped polyester sheet 21 of FIG. 2 was filled with 160 cm ³ of the mixture of the liquid 12, the fiber 13 and the particles 14 and enclosed, but here, first of these mixtures, two sheets 5A was inserted into a bag-like polyester sheet 21 as shown in FIG. 5A, and then the mixture of liquid 12 and particles 14 was filled and sealed.

  As a result of measuring the energy absorbed until the hitting core 41 stopped under the above measurement conditions and calculating the absorbed energy required for penetration, the energy absorption of 840J was measured.

(Example 5)
Other than replacing the mixture of liquid 12, fiber 13 and particle 14 (composite material = impact buffer member 11) with the following mixture of liquid 12, fiber 13, particle 14 and particle 14 ′ (composite material = impact buffer member 11) Produced the inclusion body (composite = impact reducing part) 22 in the same manner as in Example 1 and measured the absorbed energy.

Liquid 12; ethylene glycol fiber 13; woven fabric form using nylon fiber; fiber (L ₄ ) diameter 130 μm, fiber length (L ₃ ) (= length of one side of woven fabric) 90 mm, Thickness (see symbol h in FIG. 5B) 270 μm, distance between yarns of woven fabric (= between warp yarns 13a to weft yarn 13b; see symbol d in FIG. 5B) 155 μm, porosity of woven fabric 30%
Particle 14; Acicular-shaped alumina particles having a diameter (L ₂ ) of 10 nm and a length (L ₁ ) of 100 nm and an aspect ratio of 10 Particle 14 ′; Average particle diameter of 15 nm (ie, diameter (L ₂ ) of 15 nm, length (L ₁ ) Spherical silica particles having an aspect ratio of 15 nm) of approximately 1) The alumina particles 14 and the silica particles 14 'were mixed at 1: 1 (volume ratio).

Volume mixing ratio; liquid 12: fiber 13: particle (14 + 14 ′) = 70: 5: 25
Also in this example, two woven fabric fibers 13 using nylon fibers were used as shown in FIG. 5A. The size of the fiber 13 in the form of a woven fabric using the nylon fiber corresponds to the size in the enclosure (composite = impact reducing component) 22, that is, the length 90 mm × width 90 mm × thickness 270 μm. Was used. Also in this example, the bag-like polyester sheet 21 of FIG. 2 was filled with 160 cm ³ of the mixture of the liquid 12, the fiber 13, the particles 14 and the particles 14 ′ and sealed. Here, among these mixtures, Two fibers 13 were inserted into a bag-like polyester sheet 21 as shown in FIG. 5A, and then filled with a mixture of liquid 12, particles 14 and particles 14 ′ and sealed.

  As a result of measuring the energy absorbed until the hitting core 41 stopped under the above measurement conditions and calculating the absorption energy required for penetration, the energy absorption of 780J was measured.

(Comparative Example 1)
As an example of a conventional structure (buckling structure), an impact reduction component in which a ribbed plate 67 and a ribless plate 79 having the shapes shown in FIGS. The same energy absorption measurement as 1 was performed.

  Here, FIG. 6 shows a plate 67 with ribs 68. The base plate 67 has a plate thickness of 2 mm, and the rib 68 portion has a rib thickness of 1 mm and a rib height of 16 mm. Nine ribs 68 are provided at intervals of 7 mm. FIG. 7A is a plate 79 that is fitted (fitted) to the ribbed plate of FIG. 6 and is a ribless plate having a thickness of 2 mm. As shown in FIG. 7B, the impact reducing component 71 is formed by (fitting) the plate 67 with ribs 68 and the plate 79 without ribs having the shapes shown in FIGS. 6 and 7A.

  As a result of measuring the energy absorbed until the hitting core 41 stopped under the above measurement conditions and calculating the absorbed energy required for penetration, energy absorption of 280J was measured.

(Comparative Example 2)
An encapsulant (composite = impact reducing component) 22 was prepared in the same manner as in Example 1 except that the mixture (composite material = impact buffer member 11) was changed to the following, and the absorbed energy was measured.

Liquid 12; ethylene glycol fiber 13; glass fiber, diameter (L ₄ ) 15 μm, length (L ₃ ) 500 μm
Volume mixing ratio; liquid 12: fiber 13: particle 14 = 95: 5: 0
As a result of measuring the energy absorbed until the hitting core 41 stopped under the above measurement conditions and calculating the absorbed energy required for penetration, the energy absorption of 20J was measured.

  The results of Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 1.

  As shown in Table 1, from the comparison between Examples 1 to 5 and Comparative Examples 1 and 2, the impact reducing member of the present invention and the impact reducing member using the same absorb high energy despite the thin structure. I can confirm that I can do it. From this, it can be seen that the present invention can be suitably used for a part that needs shock buffering such as an automobile.

  The thickness of the impact reducing component (encapsulated body) is set to 2 cm so that the above example and the comparative example can be compared. However, in the buckling structure of the comparative example 1, when the thickness is less than this, it is no longer necessary. Since it is difficult to absorb energy and it is difficult to compare without making a body as an impact reducing part, it is 2 cm. On the other hand, in the above embodiment, the layout and appearance (design) are the object of the present invention in the installation on the interior material (for example, the back surface of the interior pillar) or the exterior material (for example, the back surface of the engine hood or the bumper). Even if it is thin (especially thickness of 1 cm or less) that does not affect the property, sufficient energy absorption can be achieved. From this point of view, for Examples 1 to 5, the amount of the mixture (impact reducing member) was further changed to produce impact reducing parts (inclusion bodies) having a thickness of 1 cm and 0.5 cm, and energy absorption was measured. However, it has been confirmed that the high energy absorption values shown in Table 1 and the results are not different from each other. At this time, in Examples 1 to 3, impact reduction parts (encapsulated bodies) having different thicknesses were produced by changing only the filling amount without changing the volume mixing ratio of the mixture. In Examples 4 and 5, the same woven fabric is used for the fibers 13, and the volume reduction ratio of the liquid and particles is not changed. ) Was produced.

  Although the present invention has been described in detail with reference to examples, the present invention is not limited to these examples, and various modifications are possible within the scope of the present invention. In addition to liquids, fibers, and particles, additives such as antioxidants and heat stabilizers, and materials surrounding them can be appropriately modified according to the intended use.

It is drawing which represented the mode of the change when the impact reduction member of this invention received the stress from the outside by a collision etc. typically. Among these, FIG. 1A schematically shows the state of the impact reducing member of the present invention in a normal state (a state in which no stress is applied from the outside due to a collision or the like) in the case of using needle-shaped particles having an aspect ratio of 5 or more. FIG. FIG. 1B is a drawing schematically showing a state when the impact reducing member of the present invention used in FIG. 1A receives stress from the outside due to a collision or the like. FIG. 1C shows a normal state of the impact-reducing member of the present invention in the case where needle-shaped particles having an aspect ratio of 5 or more and spherical particles having an aspect ratio of less than 5 are used in combination (there is no external stress due to collision or the like). It is drawing which represented the mode of (state) typically. FIG. 1D is a drawing schematically showing a state when the impact reducing member of the present invention used in FIG. 1C receives stress from the outside due to a collision or the like. It is a perspective view of the bag-shaped polyester sheet (before mixture mixture) for enclosing the mixture used for Examples 1-5 and Comparative Example 2. FIG. It is a top view of the enclosure (after enclosure) of the mixture used for Examples 1-3 and Comparative Example 2. FIG. FIG. 4 is a schematic cross-sectional view taken along line A-A ′ of FIG. 3. FIG. 5A is a schematic cross-sectional view of a mixture enclosure (after encapsulation) used in Examples 4 and 5. FIG. FIG. 5B is a schematic cross-sectional view schematically showing an enlarged part of the woven fabric using the nylon fiber used in FIG. 5A. 6A is a plan view of the ribbed plate of the structure used in Comparative Example 1, and FIG. 6B is a schematic cross-sectional view taken along line B-B ′ of FIG. 6A. 7A is a schematic cross-sectional view of another ribless plate of the structure used in Comparative Example 1. FIG. FIG. 7B is a schematic cross-sectional view of an impact reducing component of a conventional structure (buckling structure) formed by (fitting) the ribbed plate of FIG. 6 and the ribless plate of FIG. 7A. It is the schematic which represented typically the aspect-ratio and particle diameter of particle | grains, and the method of taking the diameter and length of a fiber. Among these, FIG. 8A is a schematic diagram schematically showing the aspect ratio and particle diameter of spherical solid particles. FIG. 8B is a schematic diagram schematically showing the aspect ratio and particle diameter of spherical hollow particles. FIG. 8C is a schematic drawing schematically showing how to obtain the diameter and length of solid fibers. FIG. 8D is a schematic drawing schematically showing how to take the diameter and length of the hollow fiber.

Explanation of symbols

11 Shock absorbing member (composite material = mixture (liquid + fiber + particle)),
12 liquid,
13 Fiber (glass fiber, woven fabric made of nylon fiber),
13a Woven warp,
13b Weft of woven fabric,
14 Acicular shaped particles,
14 'spherical particles,
21 Bag-shaped polyester sheet (enclosed container),
22 Impact-reducing parts (composite = encapsulated body) containing the shock-absorbing member (mixture) (after encapsulation)
23 Crimp margin (crimp part),
41
67 Base plate of ribbed plate,
68 Ribs (parts) of ribbed plates,
71 Impact-reducing parts of conventional structure (buckling structure),
79 Plate without ribs,
H Thickness of impact reducing parts (= encapsulated body),
h Thickness of woven fabric,
d Distance between yarns of woven fabric,
The maximum value of the long diameter (major axis length) of L ₁ particles,
Cross sectional length of the minor axis (short axis direction) of the L _a particle,
Minor axis of the cross section of the minor axis (short axis direction) of the L _b particles,
The maximum value of L ₃ fiber diameter of (major axis length),
L _c cross sectional length of the fiber (minor axis of)
L _d minor axis of the cross section of the fiber (minor axis) of.

Claims (6)

liquid,
Fibers having a diameter of 15 μm or more and a length of 500 μm or more, and particles,
An impact reducing member, characterized in that the particle has a needle-like shape with an aspect ratio of 5 or more.   The impact reducing member according to claim 1, wherein the fiber is used in the form of a woven fabric.   The impact reducing member according to claim 1 or 2, wherein the needle-shaped particles having an aspect ratio of 5 or more are alumina particles having a cross-sectional diameter of 5 to 1000 nm.   The impact reduction according to any one of claims 1 to 3, wherein the particles are a mixture of acicular particles having an aspect ratio of 5 or more and spherical particles having an aspect ratio of less than 5. Element.   The impact reducing member according to any one of claims 1 to 4, wherein the particle is 5 to 40 vol% of the composite material.   A pedestrian or occupant impact reduction component, wherein a composite containing the impact reduction member according to any one of claims 1 to 5 is installed in an interior and / or exterior of an automobile.

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