CN117377836A - Impact absorbing member and vehicle - Google Patents

Impact absorbing member and vehicle Download PDF

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Publication number
CN117377836A
CN117377836A CN202280035298.2A CN202280035298A CN117377836A CN 117377836 A CN117377836 A CN 117377836A CN 202280035298 A CN202280035298 A CN 202280035298A CN 117377836 A CN117377836 A CN 117377836A
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China
Prior art keywords
absorbing member
cell
impact
resin
impact absorbing
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CN202280035298.2A
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Chinese (zh)
Inventor
杉山贵之
田村翼
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Sumitomo Chemical Co Ltd
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Sumitomo Chemical Co Ltd
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Priority claimed from PCT/JP2022/020212 external-priority patent/WO2022244698A1/en
Publication of CN117377836A publication Critical patent/CN117377836A/en
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Abstract

The impact absorbing member includes a molded part containing a thermoplastic resin, the molded part having a main body part having a honeycomb structure filled with a plurality of cylindrical cells, and part or all of the cylindrical cells constituting the honeycomb structure being arranged via cell walls having a thickness gradient satisfying the relationship of the following formula (G) obtained from the following [ method of calculating a thickness gradient of cell walls ]. [ method of calculating the thickness gradient of cell wall ] step 1) sets a center axis (a) passing through one end face center of gravity and the other end face center of gravity in the first cylindrical cell having the height (H). Step 2) of setting arbitrary two surfaces (b) and (c) perpendicular to the center axis (a) within a range of the height (H) of the first cylindrical unit, and setting a distance between the two surfaces (b) and (c) as H (unit mm;0 < H < H). Step 3) is to set the thickness of the cell wall between the first tubular cell and the second tubular cell adjacent thereto at the position where the cell wall intersects the surface (b) to (t 1) (unit mm). Step 4) is to set the thickness of the cell wall between the first tubular cell and the second tubular cell adjacent thereto at a position where the cell wall intersects the surface (c) to (t 2) (unit mm). Step 5) calculating |t2-t1|/h as the thickness gradient of the cell wall.

Description

Impact absorbing member and vehicle
Technical Field
The present invention relates to an impact absorbing member and a vehicle.
The present application is based on Japanese patent application No. 2021-084347 at 5/19/2021 and Japanese patent application No. 2021-214975/2021/12/28, the contents of which are incorporated herein by reference.
Background
In structural members of vehicles such as automobiles, a reduction in weight and an improvement in collision safety are required for achieving fuel saving.
For example, in order to protect an occupant by suppressing deformation in a vehicle chamber by absorbing an impact at the time of a vehicle collision, a crash box as a structural member for absorbing an impact (hereinafter, referred to as an "impact absorbing member") is mounted in front of and behind the vehicle. The crash box is provided between a front side member (frame) extending in the front-rear direction of the vehicle and a bumper, and is crushed in the front-rear direction to absorb impact energy when a compressive force in the front-rear direction is applied to the vehicle in response to a collision.
Conventionally, the impact absorbing member is made of a metal material. However, as described above, in recent years, weight reduction of the vehicle has been desired for the purpose of saving fuel consumption and the like, and technical development for realizing lightweight and excellent impact energy absorbing performance has been also performed in the impact absorbing member.
In contrast, an impact absorbing member using a resin material as a forming material has been studied and developed.
As a structural member having high strength, a sandwich structure in which two layers of a surface and an inner layer are integrated is used for a structural member of an aircraft, an automobile member, a building member, or the like. The inner layer of the sandwich structure uses a honeycomb structure.
For example, patent document 1 proposes a honeycomb structure having an improved strength, which is formed from a resin composition containing a thermoplastic resin and reinforcing fibers.
Prior art literature
Patent literature
Patent document 1: japanese patent application laid-open No. 2015-519233.
Disclosure of Invention
Problems to be solved by the invention
As the impact absorbing member, for example, in a crash box, compression fracture is continuously generated due to an impact load applied in the front-rear direction of the vehicle, so that energy can be efficiently absorbed.
In this impact absorbing member, a large impact energy is applied in a short time at the time of collision. However, in the conventional impact absorbing members made of resin, the impact energy absorbing amount at the time of collision is low, and further improvement in the impact energy absorbing performance is required.
The present invention has been made in view of such circumstances, and an object thereof is to provide an impact absorbing member which is made of a resin material as a forming material, is reduced in weight, and is further improved in impact energy absorbing performance, and a vehicle to which the impact absorbing member is attached.
Means for solving the problems
The present invention includes the following aspects.
[1] An impact absorbing member comprising a molded part comprising a thermoplastic resin, wherein the molded part comprises a main body part having a honeycomb structure filled with a plurality of tubular cells, and wherein part or all of the tubular cells constituting the honeycomb structure are arranged via cell walls satisfying the relationship of the following formula (G) according to the thickness gradient (|t2-t1|/h) obtained by the following [ method for calculating the thickness gradient of cell walls ].
[ method for calculating thickness gradient of cell wall ]
Step 1) sets a center axis a passing through the center of gravity of one end face and the center of gravity of the other end face in the first cylindrical unit having a height H.
Step 2) setting arbitrary two surfaces b and c perpendicular to the central axis a within a range of the height H of the first cylindrical unit, and setting a distance between the two surfaces b and c to H (unit mm;0 < H < H).
Step 3) sets the thickness of the cell wall between the first cylindrical cell and the second cylindrical cell adjacent thereto at a position where the cell wall intersects the surface b to t1 (unit mm).
Step 4) sets the thickness of the cell wall between the first cylindrical cell and the second cylindrical cell adjacent thereto at a position where the cell wall intersects the surface c to t2 (unit mm).
Step 5) calculating |t2-t1|/h as the thickness gradient of the cell wall.
[2] The impact absorbing member of [1], wherein the molding portion is an injection molding portion.
[3] The impact absorbing member of [1] or [2], wherein the molding part further contains a fibrous filler.
[4] The impact absorbing member according to [3], wherein the fibrous filler contained in the molding part has a length-weighted average fiber length of 0.5mm or more.
[5] The impact absorbing member according to any one of [1] to [4], wherein the thermoplastic resin is a liquid-crystalline polyester resin.
[6] The vehicle according to any one of [1] to [5], wherein the impact absorbing member is mounted on at least one of a front portion, a rear portion, and a side portion of the vehicle.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, it is possible to provide an impact absorbing member that is lightweight by using a resin material as a forming material and that further improves impact energy absorbing performance.
In particular, according to the present invention, an improvement in the impact energy absorption amount per unit weight and the impact energy absorption efficiency is achieved.
In addition, by applying the impact absorbing member, a vehicle in which improvement in fuel consumption and collision safety has been achieved can be provided.
Drawings
Fig. 1 is a schematic view showing an example of a state in which an impact absorbing member of the present embodiment is mounted on a vehicle.
Fig. 2 is a perspective view showing an embodiment of the impact absorbing member.
Fig. 3A is a cross-sectional view in the height direction of the impact absorbing member 500.
Fig. 3B is an enlarged cross-sectional view of a portion of the cell wall 514 in fig. 3A.
Fig. 4A is a plan view (top view) showing an embodiment of a honeycomb structure which is applicable to an impact absorbing member and which is constituted of cylindrical cells having substantially regular triangle-shaped opening surfaces.
Fig. 4B is a plan view (top view) showing an embodiment of a honeycomb structure which is applicable to an impact absorbing member and which is constituted of cylindrical cells having substantially square opening surfaces.
Fig. 4C is a plan view (top view) showing an embodiment of a honeycomb structure which is applicable to an impact absorbing member and which is constituted of cylindrical cells having an opening surface of a substantially regular hexagonal shape.
Fig. 5 is a schematic view showing an example of the first particle production apparatus.
Fig. 6 is a diagram showing an apparatus for drop hammer impact test.
Fig. 7 is a graph showing the results of drop impact tests for the respective impact absorbing members in example 1 and comparative example 1.
Fig. 8 is a diagram showing a state of a test body 990 mounted on the test stand 910 when the drop impact test in the evaluation (2) is performed.
Detailed Description
The impact absorbing member mounted on the vehicle absorbs an impact applied by a collision by crushing the structural member itself at the time of the collision. Therefore, as a material of the impact absorbing member, a material having low strength and rigidity is selected. For example, conventionally, an aluminum crash box has been used as an impact absorbing member mounted on a vehicle.
The present inventors have confirmed that, in the development of a resin impact absorbing member, the maximum load applied to an aluminum crash box at the time of collision is large. When the maximum load increases, impact to the occupant protection space increases, other components are damaged, and the expected crash safety performance cannot be obtained, or repair of the vehicle body becomes difficult. Thus, as the target impact absorbing member, the maximum load applied at the time of collision is suppressed, and the desired impact energy absorption efficiency (=the impact energy absorption amount obtained from the product of the actual impact energy absorption amount/maximum load and the member displacement amount) is high.
In addition, in the resin impact absorbing member, the impact energy absorption amount at the time of collision is liable to decrease with the weight reduction. Therefore, as the target impact absorbing member, a high impact energy absorbing amount per unit weight is desired.
In order to achieve the above object, the present inventors have found that by using a "resin honeycomb structure" in a main body portion of an impact absorbing member and controlling cell walls between cells constituting the honeycomb structure to have a specific thickness, both the impact energy absorption amount per unit weight and the impact energy absorption efficiency are improved, and completed the present invention.
(impact absorbing Member)
The impact absorbing member according to one embodiment of the present invention is characterized in that it is formed of a resin main body, and various known impact absorbing members can be applied to other structures than the main body.
The impact absorbing member of the present embodiment is a structural member including a molded portion including a thermoplastic resin. The molding portion in the impact absorbing member of the present embodiment includes a main body portion having a honeycomb structure filled with a plurality of cylindrical cells. The honeycomb structure is not limited to regular hexagonal pillars, but may also include a three-dimensional space-filling three-dimensional structure in which three-dimensional patterns are arranged without voids.
Fig. 1 is a schematic view showing an example of a state in which the impact absorbing member of the present embodiment is mounted to a vehicle as a crash box.
In fig. 1, the impact absorbing member 200 of the present embodiment is provided between a front side member 400 (frame) extending in the front-rear direction of the vehicle and a bumper 300.
In the vehicle mounted with the impact absorbing member 200, if a compressive force in the front-rear direction acts on the vehicle in association with a collision, the impact absorbing member 200 collapses in the front-rear direction to absorb impact energy.
The shock absorbing member of the present embodiment will be described in order with reference to the drawings. In all the drawings below, the sizes, ratios, and the like of the constituent elements are appropriately different from the actual sizes for the convenience of viewing the drawings.
The impact absorbing member of the present embodiment includes a molded portion including a thermoplastic resin. The molding part includes a main body part having a honeycomb structure filled with a plurality of cylindrical cells. Part or all of the cylindrical cells constituting the honeycomb structure are arranged via cell walls whose thickness gradient (|t2-t1|/h) satisfies a specific relationship, which is obtained from a [ method of calculating a thickness gradient of cell walls ] described later.
Fig. 2 is a perspective view showing an embodiment of the impact absorbing member.
The impact absorbing member 500 shown in fig. 2 includes an injection molded portion 530 containing a thermoplastic resin and a fibrous filler.
The injection molded part 530 has a main body part 510.
Preferably, the injection molded part 530 has a Flange (Flange) part 520 integrally molded with the body part 510, in addition to the body part 510.
The main body 510 has a honeycomb structure in which a plurality of cylindrical cells 512 are arranged without any gaps.
Preferably, the plurality of cylindrical units 512 are formed to protrude from the flange 520.
The tubular unit 512 may be formed in a bottomed tubular shape in which an end surface on the flange 520 side is closed and an end surface on the opposite side to the flange 520 side is opened.
In fig. 2, the honeycomb structure provided in the main body 510 has an opening surface of the tubular cells 512 having a substantially regular hexagonal shape in a plan view, and is composed of 32 tubular cells 512.
In the impact absorbing member 500, all of the cylindrical cells 512 constituting the honeycomb structure are arranged via the cell walls 514 whose thickness gradient (|t2-t1|/h) satisfies the relationship of the following expression (G) obtained from the following [ method of calculating the thickness gradient of the cell walls ].
Fig. 3A and 3B are diagrams illustrating [ a method of calculating a thickness gradient of cell walls ] in the honeycomb structure provided in the main body 510.
Fig. 3A is a sectional view of the impact absorbing member 500 in the height direction.
In fig. 3A, a cell wall 514 is formed by a first cylindrical cell 512a and a second cylindrical cell 512b adjacent thereto.
Fig. 3B is an enlarged cross-sectional view of a portion of the cell wall 514 in fig. 3A.
The [ method for calculating the thickness gradient of cell walls ] in the honeycomb structure is obtained as follows.
[ method for calculating thickness gradient of cell wall ]
Step 1) sets a center axis a passing through the center of gravity of the end face on the flange 520 side and the center of gravity of the end face on the opposite side of the flange 520 side in the first cylindrical unit 512a having the height H.
Step 2) setting arbitrary two surfaces b and c perpendicular to the central axis a within the range of the height H of the first cylindrical unit 512a, and setting the distance between the two surfaces b and c as H (unit mm;0 < H < H).
Step 3) sets the thickness of the cell wall 514 at the position where the cell wall 514 intersects the surface b between the first tubular cell 512a and the second tubular cell 512b adjacent thereto to t1 (unit mm).
Step 4) sets the thickness of the cell wall 514 at the position where the cell wall 514 intersects the surface c between the first tubular cell 512a and the second tubular cell 512b adjacent thereto to t2 (unit mm).
Step 5) calculates |t2-t1|/h as the thickness gradient of cell wall 514.
In the impact absorbing member 500, |t2-t1|/h, which is the thickness gradient of the cell walls 514, is greater than 62.5x10 -4 And less than 250 x 10 -4 Preferably 65X 10 -4 200X 10 of the above -4 Hereinafter, it is more preferably 100X 10 -4 Above and 150×10 -4 The following is given.
The thickness gradient of the cell walls 514 is greater than the lower limit value, so that the impact energy absorbing performance is further improved. On the other hand, the thickness gradient of the cell walls 514 is smaller than the upper limit value, so that the honeycomb structure can be easily molded.
The size of the impact absorbing member 500 can be appropriately set according to the installation object (for example, the type, size, etc. of the vehicle), the required impact energy absorbing performance, etc.
For example, the height H of the first cylindrical unit 512a is 20 to 200mm.
In |t2-t1|/H, the distance H between the two surfaces b, c is in the range of 0 < H < H, preferably H/2 < H < 4H/5. In particular, the height from the flange 520 is preferably set such that the midpoint of the height H is located at the same position as the midpoint of the distance H.
The thickness t1 of the cell wall 514 at the position where the cell wall 514 intersects the surface b is, for example, 0.5 to 5mm.
The thickness t2 of the cell wall 514 at the position where the cell wall 514 intersects the surface c is, for example, 0.5 to 5mm.
The thickness t1 and the thickness t2 may be t1 > t2, or t1 < t2. That is, in the shock absorbing member 500, the cylindrical unit 512 may be gradually thicker from the opening surface side toward the flange portion 520 side, or may be gradually thicker from the flange portion 520 side toward the opening surface side. However, from the viewpoint of moldability of the honeycomb structure, t1 < t2 is preferable.
The inner diameter of the end surface (opening surface) of the tubular unit 512 opposite to the flange 520 is, for example, 5 to 50mm, preferably 5 to 20mm. The cell inner diameter represents the diameter of an inscribed circle of the opening surface of the tubular cell, and when the opening surface is substantially regular hexagonal, represents the diameter of an inscribed circle of substantially regular hexagon.
The thickness of the flange 520 is, for example, 2 to 6mm.
The impact absorbing member 500 can be manufactured by, for example, melting a resin material using a known injection molding machine, and injecting the melted resin material into a mold having a honeycomb structure.
The thickness gradient (|t2-t1|/h) of the cell walls 514 can be controlled by, for example, the shape of the mold such as the inner diameter of the cylindrical cell 512, the height of the cylindrical cell 512, and the like.
Examples of the known injection molding machine include TR450EH3 manufactured by sandik corporation and a hydraulic horizontal molding machine PS40E5ASE type manufactured by daily resin industry.
The resin material of the present embodiment will be described in detail later.
The temperature conditions for injection molding are appropriately determined depending on the type of thermoplastic resin, and it is preferable to set the barrel temperature of the injection molding machine to a temperature 10 to 80 ℃ higher than the flow start temperature of the thermoplastic resin used.
For example, the melt kneading temperature of the plasticizing part is preferably 250 to 350 ℃, more preferably 280 to 340 ℃, and even more preferably 290 to 330 ℃. The metering section or plunger section is preferably 250 to 400 ℃, more preferably 290 to 380 ℃, and even more preferably 300 to 370 ℃.
From the viewpoints of cooling rate and productivity of the thermoplastic resin, the temperature of the mold is preferably set in the range of room temperature (e.g., 23 ℃) to 220 ℃.
As other injection conditions, screw rotation number, back pressure, injection speed, dwell time, and the like may be appropriately adjusted.
In the present embodiment, the gate method is not particularly limited, but from the viewpoint of suppressing the generation of the weld line at the injection molding portion 530, it is preferable to use direct gate from the vicinity of the center of gravity of the bottom surface of the flange portion 520 or film gate from the side surface of the flange portion 520. By adopting the gate method, the injection molding portion 530 can be molded while suppressing the occurrence of the weld line, and the impact energy absorbing performance can be more easily improved.
In the present embodiment, in the gate method, from the viewpoints of controllability of the fiber length deviation and long fiber formation in the injection molding portion 530, it is more preferable to perform direct gate from the vicinity of the center of gravity of the bottom surface of the flange portion 520 (that is, to provide a gate mark in the vicinity of the center of gravity of the bottom surface of the flange portion 520).
The impact absorbing member 500 of the embodiment described above has a resin main body 510 containing a thermoplastic resin and a fibrous filler. Therefore, according to the impact absorbing member 500, the weight is reduced as compared with the conventional impact absorbing member made of a metal material, and fuel consumption is reduced.
In addition, the impact absorbing member 500 includes a main body 510, and the main body 510 includes a honeycomb structure filled with a plurality of cylindrical cells 512, and the cylindrical cells 512 are formed by the above-described [ cell wall thickness gradient calculating method ]]The thickness gradient (|t2-t1|/h) determined satisfies more than 62.5X10 -4 And less than 250 x 10 -4 Is arranged in relation to cell walls 514. Therefore, according to the impact absorbing member 500, the impact energy absorbing performance is further improved, thereby achieving an improvement in collision safety.
In the impact absorbing member 500 of the above embodiment, the honeycomb structure in the main body portion 510 may have an outer layer surrounding the side surfaces thereof.
In the shock absorbing member 500, the flange 520 may be processed to be attached to another component. For example, one or more through holes for bolting to other structural members may be provided at fixed intervals in the flange portion 520.
In addition, in the impact absorbing member 500, processing for attachment to other structural members may be performed in the vicinity of the upper side surface of the main body 510.
< other embodiments >
The impact absorbing member according to one embodiment of the present invention is not limited to the above embodiment, and may be another embodiment.
The shock absorbing member 500 is configured such that all of the cylindrical cells 512 constituting the honeycomb structure are arranged via the cell walls 514 having the thickness gradient (|t2-t1|/h) satisfying the relation of the formula (G), but the shock absorbing member is not limited thereto, and may be configured such that a part of the cylindrical cells 512 constituting the honeycomb structure are arranged via the cell walls 514 having the thickness gradient (|t2-t1|/h) satisfying the relation of the formula (G).
The cylindrical cells 512 arranged through the cell walls 514 satisfying the relation of the above formula (G) are preferably 70% to 100%, more preferably 90% to 100% of the total cylindrical cells 512 constituting the honeycomb structure.
The impact absorbing member 500 includes an injection molded portion, but is not limited thereto, and may include a molded portion obtained by processing an extruded sheet, for example. However, it is preferable to include an injection molding part from the viewpoints of higher impact energy absorbing performance, strength, and ease of molding.
In the impact absorbing member 500, the honeycomb structure provided in the main body 510 has a substantially regular hexagonal shape in plan view, but the opening surfaces of the tubular cells 512 are not limited thereto, and may have other shapes as long as the tubular cells can be arranged via cell walls whose thickness gradient (|t2-t1|/h) satisfies the relationship of the formula (G).
Fig. 4A, 4B, and 4C are plan views (top surface views) showing embodiments of a honeycomb structure applicable to an impact absorbing member.
Fig. 4A shows an embodiment in which the opening surfaces of the cylindrical cells constituting the honeycomb structure have a substantially regular triangle shape. Reference numeral 514a denotes a cell wall.
Fig. 4B shows an embodiment in which the opening surfaces of the cylindrical cells constituting the honeycomb structure have a substantially square shape. Reference numeral 514b denotes a cell wall.
Fig. 4C shows an embodiment in which the opening surfaces of the cylindrical cells constituting the honeycomb structure have a substantially regular hexagonal shape. Reference numeral 514c denotes a cell wall.
In the impact absorbing member 500, when the honeycomb structure of the main body 510 has a shape having a vertex, such as a substantially regular polygon shape, as the opening surface of the tubular unit 512 in a plan view, the radius of curvature of the vertex is preferably 0.5mm or more.
As used herein, the term "radius of curvature of the apex" refers to the radius of the circle when considering that the tiny portion including the apex approximates an arc of a circle.
In the impact absorbing member 500, the honeycomb structure of the main body 510 is composed of 32 cylindrical units 512, but the number of the cylindrical units is not limited thereto, and may be appropriately set according to the installation object (for example, the type, size, etc. of the vehicle), the required impact energy absorbing performance, etc. The number of the cylindrical units is, for example, in the range of 10 to 70. The inner diameter of the opening surface of the tubular unit can be set appropriately in the same manner as the number of tubular units.
The impact absorbing member 500 is provided with the injection molding part 530 containing the thermoplastic resin and the fibrous filler, but the present invention is not limited thereto, and may be provided without containing the fibrous filler. However, the molded part contains a fibrous filler in addition to the thermoplastic resin, so that the impact energy absorbing performance is further improved and the durability is improved.
< resin Material >)
The injection molding part 530 in the impact absorbing member 500 of the present embodiment contains a thermoplastic resin and a fibrous filler.
In the injection molding portion 530, the ratio (mass ratio) of the thermoplastic resin to the fibrous filler is preferably 40 to 75 parts by mass, more preferably 45 to 75 parts by mass, and further preferably 25 to 55 parts by mass, further preferably 45 to 70 parts by mass, and particularly preferably 30 to 55 parts by mass, and particularly preferably 50 to 70 parts by mass, and 30 to 50 parts by mass.
If the ratio of the fibrous filler is not less than the lower limit of the preferable range, the use of the fibrous filler can achieve the effect of improving the strength of the injection molded part. On the other hand, if the upper limit of the preferable range is not more than the above, the fibrous filler is easily dispersed in the thermoplastic resin, and fiber breakage due to collision between fibers is less likely to occur in injection molding.
The total content of the thermoplastic resin and the fibrous filler in the injection molded part 530 is preferably 80 mass% or more, more preferably 90 mass% or more, still more preferably 95 mass% or more, and may be 100 mass% or more, with respect to the total amount (100 mass%) of the injection molded part.
Thermoplastic resin
Examples of the thermoplastic resin in the present embodiment include liquid crystal polyester resins, polyamides, polypropylene, polyesters other than liquid crystal polyester resins, polysulfones, polyether sulfones, polyphenylene sulfides, polyether ketones, polyether ether ketones, polycarbonates, polyphenylene oxides, and polyether imides. Among them, from the viewpoint of impact energy absorption performance, liquid crystal polyester resins, polyamides, and polypropylene are preferably used, and from the viewpoint of low water absorption dependency and higher impact energy absorption performance in a hygroscopic state, liquid crystal polyester resins are particularly preferably used.
Examples of the polyamide include nylon 6 (PA 6), nylon 66, nylon 11, nylon 12, nylon 46, nylon 610, polytetramethylene terephthalamide (nylon 4T), polyhexamethylene terephthalamide (nylon 6T), polyhexamethylene isophthalamide (nylon MXD 6), polyhexamethylene terephthalamide (nylon 9T), and polydecylene terephthalamide (nylon 10T).
For liquid crystalline polyester resins:
in the present embodiment, the liquid crystal polyester resin is a polyester exhibiting liquid crystallinity in a molten state, and is preferably a polyester that melts at a temperature of 400 ℃ or less.
The preferable liquid crystal polyester resin contained in the molded part of the impact absorbing member may be a liquid crystal polyester amide, a liquid crystal polyester ether, a liquid crystal polyester carbonate, or a liquid crystal polyester imide.
The liquid crystal polyester resin is preferably a wholly aromatic liquid crystal polyester obtained by using only an aromatic compound as a raw material monomer.
Typical examples of the liquid crystal polyester resin include: a liquid crystal polyester resin obtained by polymerizing (polycondensing) an aromatic hydroxycarboxylic acid and an aromatic dicarboxylic acid with at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxylamine, and an aromatic diamine; a liquid crystal polyester resin obtained by polymerizing a plurality of aromatic hydroxycarboxylic acids; a liquid crystal polyester resin obtained by polymerizing an aromatic dicarboxylic acid with at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxylamine and an aromatic diamine; and a liquid crystal polyester resin obtained by polymerizing a polyester such as polyethylene terephthalate with an aromatic hydroxycarboxylic acid.
Here, the polymerizable derivatives of the aromatic hydroxycarboxylic acid, the aromatic dicarboxylic acid, the aromatic diol, the aromatic hydroxylamine, and the aromatic diamine may be used, respectively, in place of some or all of them.
Examples of polymerizable derivatives of compounds having a carboxyl group such as an aromatic hydroxycarboxylic acid and an aromatic dicarboxylic acid include esters obtained by converting a carboxyl group into an alkoxycarbonyl group or an aryloxycarbonyl group, acid chlorides obtained by converting a carboxyl group into a haloformyl group, and acid anhydrides obtained by converting a carboxyl group into an acyloxycarbonyl group. Examples of polymerizable derivatives of compounds having a hydroxyl group such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxyamines include acylates obtained by acylating a hydroxyl group to convert it to an acyloxy group. Examples of polymerizable derivatives of compounds having an amino group such as aromatic hydroxylamine and aromatic diamine include acylate obtained by acylating an amino group to convert it into an amido group.
The liquid crystal polyester resin preferably has a repeating unit represented by the following formula (1) (hereinafter, sometimes referred to as "repeating unit (1)"), more preferably has a repeating unit (1), a repeating unit represented by the following formula (2) (hereinafter, sometimes referred to as "repeating unit (2)"), and a repeating unit represented by the following formula (3) (hereinafter, sometimes referred to as "repeating unit (3)").
(1)-O-Ar 1 -CO-
(2)-CO-Ar 2 -CO-
(3)-X-Ar 3 -Y-
(Ar 1 Represents phenylene, naphthylene or biphenylene. Ar (Ar) 2 And Ar is a group 3 Each independently represents a phenylene group, a naphthylene group, a biphenylene group, or a group represented by the following formula (4). X and Y each independently represent an oxygen atom or an imino group (-NH-). From Ar 1 、Ar 2 Or Ar 3 The hydrogen atoms in the groups represented may each be independently substituted with a halogen atom, an alkyl group or an aryl group. )
(4)-Ar 4 -Z-Ar 5 -
(Ar 4 And Ar is a group 5 Each independently represents a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group or an alkylene group. )
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-hexyl, 2-ethylhexyl, n-octyl and n-decyl, and the number of carbon atoms is preferably 1 to 10. Examples of the aryl group include phenyl, o-tolyl, m-tolyl, p-tolyl, 1-naphthyl and 2-naphthyl groups, and the number of carbon atoms is preferably 6 to 20.
When the hydrogen atom is substituted with these groups, the substitution numbers thereof are each Ar 1 、Ar 2 Or Ar 3 The number of the groups represented is preferably 2 or less, more preferably 1 or less, each independently.
Examples of the alkylene group include methylene, ethylene, isopropylene, n-butylene and 2-ethylhexyl, and the number of carbon atoms is preferably 1 to 10.
The repeating unit (1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid. As the repeating unit (1), ar is preferable 1 Repeating units (repeating units derived from parahydroxybenzoic acid) which are 1, 4-phenylene and Ar 1 Is a repeating unit of 2, 6-naphthylene (repeating unit derived from 6-hydroxy-2-naphthoic acid).
In the present specification, "derived from" means that the chemical structure of the functional group contributing to polymerization is changed to polymerize the raw material monomer without other structural changes.
The repeating unit (2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid. As the repeating unit (2), ar is preferable 2 Repeating units (repeating units derived from terephthalic acid) of 1, 4-phenylene, ar 2 Repeating units (repeating units derived from isophthalic acid) of 1, 3-phenylene, ar 2 Repeating units of 2, 6-naphthylene (repeating units derived from 2, 6-naphthalenedicarboxylic acid) and Ar 2 Is a repeating unit of diphenyl ether-4, 4 '-diyl (a repeating unit derived from diphenyl ether-4, 4' -dicarboxylic acid).
The repeating unit (3) is a repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine or aromatic diamine. As the repeating unit (3), ar is preferable 3 Repeating units (repeating units derived from hydroquinone, p-aminophenol or p-phenylenediamine) which are 1, 4-phenylene and Ar 3 Is a repeating unit of 4,4 '-biphenylene (repeating units derived from 4,4' -dihydroxybiphenyl, 4-amino-4 '-hydroxybiphenyl, or 4,4' -diaminobiphenyl).
The content of the repeating unit (1) is preferably 30 mol% or more, more preferably 30 mol% or more and 80 mol% or less, further preferably 40 mol% or more and 70 mol% or less, particularly preferably 45 mol% or more and 65 mol% or less, based on the total amount of all the repeating units. In the present specification, the total amount of all the repeating units is a value obtained by dividing the mass of each repeating unit constituting the liquid crystal polyester resin by the chemical formula amount of each repeating unit to obtain the amount (mol) of each repeating unit corresponding to the amount of the substance, and adding the amounts together.
The content of the repeating unit (2) is preferably 35 mol% or less, more preferably 10 mol% or more and 35 mol% or less, further preferably 15 mol% or more and 30 mol% or less, particularly preferably 17.5 mol% or more and 27.5 mol% or less, based on the total amount of all the repeating units.
The content of the repeating unit (3) is preferably 35 mol% or less, more preferably 10 mol% or more and 35 mol% or less, further preferably 15 mol% or more and 30 mol% or less, particularly preferably 17.5 mol% or more and 27.5 mol% or less, based on the total amount of all the repeating units.
The more the content of the repeating unit (1), the more easily the melt flowability, heat resistance, strength and rigidity are improved, but when the content is too large, the melting temperature and melt viscosity are easily increased, and the temperature required for molding is easily increased.
The ratio of the content of the repeating unit (2) to the content of the repeating unit (3) is represented by [ the content of the repeating unit (2 ]/[ the content of the repeating unit (3) ] (mol/mol), and is preferably 0.9/1 to 1/0.9, more preferably 0.95/1 to 1/0.95, still more preferably 0.98/1 to 1/0.98.
The preferable liquid crystal polyester resin contained in the molded part of the impact absorbing member may have two or more kinds of repeating units (1) to (3) independently. The liquid crystal polyester resin may have repeating units other than the repeating units (1) to (3), but the content thereof is preferably 10 mol% or less, more preferably 5 mol% or less, based on the total amount of all the repeating units.
Since the melt viscosity of the liquid crystal polyester resin tends to be low, it is preferable that the resin has a repeating unit in which X and Y are oxygen atoms respectively as the repeating unit (3), that is, a repeating unit derived from an aromatic diol, and it is more preferable that the resin has only a repeating unit in which X and Y are oxygen atoms respectively as the repeating unit (3).
Preferably, the liquid crystal polyester resin is produced by melt-polymerizing a raw material monomer corresponding to a repeating unit constituting the liquid crystal polyester resin and solid-phase polymerizing the resulting polymer (hereinafter, sometimes referred to as "prepolymer"). This enables to manufacture a high molecular weight liquid crystal polyester resin having high heat resistance, strength and rigidity with good handleability.
Melt polymerization may also be carried out in the presence of a catalyst. Examples of the catalyst include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide, and nitrogen-containing heterocyclic compounds such as 4- (dimethylamino) pyridine and 1-methylimidazole, and nitrogen-containing heterocyclic compounds are preferably used.
The flow start temperature of the liquid crystal polyester resin contained in the molded part of the impact absorbing member is preferably 260 ℃ or higher, more preferably 260 ℃ or higher and 400 ℃ or lower, and still more preferably 260 ℃ or higher and 380 ℃ or lower.
The higher the flow start temperature of the liquid crystal polyester resin, the more the heat resistance and strength of the liquid crystal polyester resin tend to be improved. On the other hand, when the flow initiation temperature of the liquid crystal polyester resin is more than 400 ℃, the melting temperature and the melt viscosity of the liquid crystal polyester resin tend to be high. Therefore, the temperature required for molding the liquid crystal polyester resin tends to be high.
In the present specification, the flow initiation temperature of the liquid crystal polyester resin is also referred to as the sticking flow temperature or the flow temperature, and is a temperature which is a standard for the molecular weight of the liquid crystal polyester resin (see "liquid crystal Polymer-Synthesis, molding and application-" written by Xiaozhi, kyowa, CMC,1987, 6, 5, p.95).
Method for measuring flow initiation temperature:
the flow initiation temperature means that the liquid-crystalline polyester resin was subjected to a capillary rheometer at 9.8MPa (100 kg/cm 2 ) The melt was melted while being heated at a rate of 4℃per minute under a load, and when extruded from a nozzle having an inner diameter of 1mm and a length of 10mm, the liquid crystalline polyester resin was at a temperature at which the liquid crystalline polyester resin had a viscosity of 4800 Pa.s (48000 poise).
In the present embodiment, the liquid crystal polyester resin may be used singly or in combination of two or more.
When two or more liquid crystal polyester resins are used in combination, as described later, liquid crystal polyester resins having different flow initiation temperatures are preferably used in combination.
The proportion of the liquid crystal polyester resin in the thermoplastic resin contained in the molded part of the impact absorbing member is 10 mass% or more, preferably 25 mass% or more, more preferably 50 mass% or more, still more preferably 75 mass% or more, particularly preferably 90 mass% or more, and may be 100 mass% or more, based on the total amount (100 mass%) of the thermoplastic resin.
The content of the liquid crystal polyester resin in the molded part in the impact absorbing member is preferably 40 to 75% by mass, more preferably 45 to 75% by mass, further preferably 45 to 70% by mass, particularly preferably 50 to 70% by mass, relative to the total amount of the molded part (100% by mass).
Fibrous filler
The fibrous filler contained in the molded portion of the impact absorbing member may be either a fibrous inorganic filler or a fibrous organic filler.
As the fibrous inorganic filler, glass fibers are mentioned; carbon fibers such as PAN-based, pitch-based, rayon-based, phenol-based, lignin-based carbon fibers; ceramic fibers such as silica fibers, alumina fibers, and silica alumina fibers; metal fibers such as iron, gold, copper, aluminum, brass, stainless steel, etc.; silicon carbide fiber and boron fiber. The fibrous inorganic filler may be a whisker such as potassium titanate whisker, barium titanate whisker, wollastonite whisker, aluminum borate whisker, silicon nitride whisker, or silicon carbide whisker.
Examples of the fibrous organic filler include polyester fibers, para-or meta-aromatic polyamide fibers, and poly-p-Phenylene Benzobisoxazole (PBO) fibers.
In view of abrasion load and availability to the apparatus during molding, the fibrous filler is more preferably at least one selected from the group consisting of PAN-based or pitch-based carbon fibers and glass fibers. In order to impart conductivity, fibrous fillers coated with metals such as nickel, copper, and ytterbium may be used.
The tensile strength of the carbon fiber is preferably 2000MPa or more, more preferably 3000MPa or more, and even more preferably 4000MPa or more. The tensile elongation of the carbon fiber is preferably 0.5% or more, more preferably 1.0% or more, and even more preferably 1.8% or more. The use of carbon fibers having high tensile strength and high elongation as the fibrous filler suppresses fiber breakage in the processing steps up to the production of the molded article, and the effect of the present invention can be easily obtained by leaving the fibers for a long period of time.
Among them, PAN-based carbon fibers can be preferably used from the viewpoint that the balance of tensile strength, tensile elastic modulus, and tensile elongation is good and the residual fiber length can be left for a long period of time.
Examples of the PAN-based carbon fiber include "TORAYCA (registered trademark)" manufactured by ori corporation, "PYROFIL (registered trademark)" manufactured by mitsubishi chemical corporation, and "Tenax (registered trademark)" manufactured by imperial corporation.
Examples of the pitch-based carbon fibers include "Dialead (registered trademark)" manufactured by mitsubishi chemical corporation, "GRANOC (registered trademark)" manufactured by japan graphite fiber corporation, "donaarbo (registered trademark)" manufactured by osaka gas chemical corporation, and "Kreca (registered trademark)" manufactured by Wu Yu corporation.
Examples of glass fibers include E glass (i.e., alkali-free glass), S glass or T glass (i.e., high strength, high elastic glass), C glass (i.e., acid-resistant glass), D glass (i.e., low dielectric constant glass), ECR glass (i.e., free of B) 2 O 3 、F 2 E glass instead of glass), AR glass (i.e., glass for alkali-resistant use), and the like.
In the molded portion of the impact absorbing member, from the viewpoints of imparting balance of strength and elastic modulus to collision load and easiness of acquisition, glass fiber is preferably used as the fibrous filler, and among these, E glass is particularly preferably used.
The length-weighted average fiber length of the fibrous filler contained in the molded part of the impact absorbing member is preferably 0.5mm or more, more preferably 1.0mm or more, and still more preferably 1.5mm or more.
When the length-weighted average fiber length of the fibrous filler is equal to or greater than the lower limit value of the preferable range, the impact angle dependence is low, and the impact energy absorption amount is easily increased regardless of the impact angle. Further, the scattering of fragments can be further suppressed by the collision damage.
On the other hand, the length-weighted average fiber length of the fibrous filler contained in the molding part is preferably 20mm or less, more preferably 15mm or less, further preferably 10mm or less, and particularly preferably 8mm or less.
When the length-weighted average fiber length of the fibrous filler is equal to or less than the upper limit value of the preferable range, the melt fluidity of the resin composition is good during injection molding, and the cell walls of the honeycomb structure are easily thinned and the cell inner diameter is easily reduced.
The length-weighted average fiber length of the fibrous filler contained in the molding part is preferably 0.5mm or more and 20mm or less, more preferably 1.0mm or more and 15mm or less, still more preferably 1.5mm or more and 15mm or less, particularly preferably 1.5mm or more and 10mm or less, and most preferably 1.5mm or more and 8mm or less.
[ measurement of the Length-weighted average fiber Length of fibrous Filler contained in Molding portion ]
The length-weighted average fiber length of the fibrous filler contained in the molding section was determined as follows.
Step (1): the maximum length (length of the longest part in the projection plane of the test piece) cut out from the outermost wall of the main body part is 20mm or more, the maximum vertical length (length of the longest part in the direction of 90 degrees from the maximum length) is 20mm or more, and the projection area of the test piece is 200mm 2 The test piece above.
Step (2): and heating the test piece at 500-600 ℃ for 1-4 hours by using a muffle furnace to remove the resin component.
Step (3): in step (2), a substance (fiber alone) from which a resin component was removed from the cut test piece was dispersed in 1000mL of an aqueous solution containing 0.05% by volume of a surfactant (manufactured by Micro90INTERNATIONAL PRODUCTS CORPORATION Co.) to prepare a dispersion.
Step (4): 100mL of the dispersion was taken out, and diluted 5 to 15 times with pure water. 50mL of the diluted dispersion was taken out and dispersed in a culture dish, and then the fibers dispersed in the culture dish were observed with a microscope (20 times magnification of VH-ZST (manufactured by KEYENCE Co.). 10 images were taken for each sample in such a manner that the photographing areas did not overlap.
Step (5): the length of all fibers present in one image taken was determined with a microscopic measuring tool. The bent fibers were measured by multipoint-to-multipoint measurement. The same procedure was sequentially performed using 10 images taken until the total number of fibers measured was greater than 500, and the fiber length was measured.
Step (6): from the fiber length of the fibers measured in step (5), the length weighted average fiber length (lm) of the fibrous filler contained in the molding section is obtained (Σni > 500).
lm＝(Σli 2 ×ni)/(Σli×ni)
li: fiber length of fibrous filler
ni: number of fibrous fillers of fiber length li
The content of the fibrous filler in the molded part in the impact absorbing member is preferably 25 to 60% by mass, more preferably 30 to 55% by mass, and even more preferably 30 to 50% by mass, relative to the total amount of the molded part (100% by mass).
Other ingredients
The molded part of the impact absorbing member may contain, in addition to the thermoplastic resin and the fibrous filler, one or more other fillers, additives, and the like, as required.
The other filler may be a plate filler, a spherical filler, or other granular filler. The other filler may be an inorganic filler or an organic filler.
Examples of the plate-like inorganic filler include talc, mica, graphite, wollastonite, glass flakes, barium sulfate, and calcium carbonate. The mica may be muscovite, phlogopite, fluorophlogopite, or tetrasilicis mica.
Examples of the particulate inorganic filler include silica, alumina, titanium oxide, glass beads, glass hollow spheres, boron nitride, silicon carbide, and calcium carbonate.
Examples of the additives include a metering stabilizer, a flame retardant, a conductivity-imparting material agent, a crystal nucleating agent, an ultraviolet absorber, an antioxidant, a vibration absorber, an antibacterial agent, an insect repellent, a deodorant, a coloring inhibitor, a heat stabilizer, a mold release agent, an antistatic agent, a plasticizer, a lubricant, a colorant, a pigment, a dye, a foaming agent, a defoaming agent, a viscosity regulator, and a surfactant.
In the present embodiment, for example, a resin composition containing a thermoplastic resin and a fibrous filler is used as the resin material. The form of the resin composition is not particularly limited, and examples thereof include particles such as powdery mixtures of thermoplastic resins, fibrous fillers and other components as needed, resin particles, and pure material particles.
In the case of manufacturing the impact absorbing member of the present embodiment, it is preferable to use particles as the resin material from the viewpoints of controllability of fiber length deviation and long fiber formation in the molding part.
For example, the particles are particularly preferably used as the particle mixture obtained in [ step of obtaining particle mixture ] shown below.
[ procedure for obtaining particle mixture ]
In the step of obtaining the particle mixture in the present embodiment, the first particles and the second particles are mixed to obtain the particle mixture.
The first particles are composed of a resin structure body in which a first thermoplastic resin is impregnated into the fibrous filler.
For example, the first thermoplastic resin and, if necessary, other components are melt-kneaded to obtain a melt, which is impregnated into the fibrous filler and granulated, whereby the first particles are obtained as particles in a state where the fibrous filler is fixed to the first thermoplastic resin.
Fig. 5 shows an embodiment of the apparatus for producing the first particles.
In the present embodiment shown in fig. 5, a case will be described in which a fiber roving (winding) 10 in which a plurality of fiber bundles 11 of fibrous filler are wound in a roll shape is used to obtain pellets 15 composed of a first thermoplastic resin composition.
As shown in fig. 5, the manufacturing apparatus 100 includes a preheating unit 121, an impregnating unit 123, a cooling unit 125, a drawing unit 127, a cutting unit 129, and conveying rollers 101 to 109. In the manufacturing apparatus 100 shown in fig. 5, the extruder 120 is connected to the impregnation section 123.
Fig. 5 shows a state in which the fiber bundles 11 are continuously fed out from the fiber roving 10. In the present embodiment, the pellets 15 of the first thermoplastic resin composition are produced while the fiber bundles 11 fed from the fiber roving 10 are conveyed in the longitudinal direction by the conveying rollers 101 to 109.
The fineness of the fiber roving 10 used in the production of the first particles of the present embodiment is not particularly limited, but is preferably 200g/1000m or more, more preferably 500g/1000m or more, and still more preferably 800g/1000m or more. When the fineness of the fiber roving 10 is equal to or greater than the lower limit value of the preferable range, the fiber roving 10 can be easily handled in the method for producing the first particles.
The fineness of the fiber roving 10 is preferably 3750g/1000m or less, more preferably 3200g/1000m or less, and still more preferably 2500g/1000m or less. When the fineness of the fiber roving 10 is equal to or less than the upper limit value of the preferable range, the fibers are easily dispersed in the first thermoplastic resin. In addition, the fibers are easy to handle when the first particles are manufactured.
That is, the fineness of the fiber roving 10 is preferably 200g/1000m or more and 3750g/1000m or less, more preferably 800g/1000m or more and 2500g/1000m or less.
The number average fiber diameter of the fiber roving 10 is not particularly limited, but is preferably 1 to 40. Mu.m, more preferably 3 to 35. Mu.m.
When the fibrous filler is carbon fiber, it is preferably 1 to 15. Mu.m, more preferably 3 to 10. Mu.m, still more preferably 4 to 9. Mu.m.
When the fibrous filler is a glass fiber, it is preferably 5 to 35. Mu.m, more preferably 10 to 25. Mu.m, still more preferably 10 to 20. Mu.m.
As the number average fiber diameter of the fiber roving 10, an average value of values obtained by observing the fibrous filler by a scanning electron microscope (1000 times) and measuring the fiber diameter of 500 randomly selected fibrous fillers was used.
When the number average fiber diameter of the fiber roving 10 is equal to or greater than the lower limit value of the preferable range, the fibrous filler is easily dispersed in the first particles. In addition, the fibrous filler is easy to handle when the first particles are manufactured. On the other hand, when the upper limit of the preferable range is not more than the upper limit, the molded article is efficiently reinforced with the fibrous filler. Therefore, excellent impact strength can be imparted to the molded portion in the impact absorbing member.
In this embodiment, a filler treated with a bundling agent is used as the fibrous filler. The fibrous filler after appropriately sizing (sizing) treatment is excellent in productivity and quality stability when producing particles, and can reduce physical property variation in the molding part.
The bundling agent is not particularly limited, and examples thereof include nylon-based polymers, polyether-based polymers, epoxy-based polymers, ester-based polymers, urethane-based polymers, or a mixture of these polymers or modified polymers of these polymers. In addition, known coupling agents such as so-called silane coupling agents such as aminosilane and epoxysilane, and titanium coupling agents can be used.
The fibrous filler used in the first particle of the present embodiment is not necessarily arranged in one direction, but from the viewpoint of productivity in the process of producing a molding material, it is preferable that the individual fibers are arranged in one direction and the fiber bundles are continuous in the longitudinal direction of the fibers.
When the fibrous filler is glass fiber, the number of individual yarns of the fiber roving 10 is preferably 1000 or more and 10000 or less, more preferably 1000 or more and 8000 or less, and even more preferably 1500 or more and 6000 or less, from the viewpoint of improving economy and impregnation.
In the case where the fibrous filler is carbon fiber, the number of single yarns of the fiber roving 10 is preferably 10000 or more and 100000 or less, more preferably 10000 or more and 50000 or less, and still more preferably 10000 or more and 30000 or less from the same point of view.
In the preheating section 121, the fiber bundle 11 fed out from the fiber roving 10 is heated and dried. The heating temperature at this time is not particularly limited, and is, for example, 50 to 250 ℃.
The heating time in the preheating part 121 is not particularly limited, and is, for example, 3 to 30 seconds.
In the impregnation section 123, the molding material M (first thermoplastic resin, and other components blended as necessary) other than the fiber bundle 11 is impregnated into the fiber bundle 11.
As will be described later, the first thermoplastic resin is preferably appropriately selected in consideration of the type of the second thermoplastic resin, melt viscosity, flow start temperature, and the like. For example, as the first thermoplastic resin, a liquid crystal polyester resin is preferable.
The first thermoplastic resin may be used alone or in combination of two or more.
The fiber bundle 11 may be impregnated with a melt obtained by feeding the molding material M from the feeding port 123a and heating the inside of the impregnation section 123, or the fiber bundle 11 may be impregnated with the molding material M melt-kneaded by the extruder 120 from the feeding port 123 a.
In the embodiment shown in fig. 5, the resin structure 13 is obtained by impregnating the fiber bundles 11 with the melt and coating the same.
The heating temperature in the impregnation section 123 is appropriately determined according to the type of the first thermoplastic resin, and is preferably set to a temperature 10 to 80 ℃ higher than the flow start temperature of the first thermoplastic resin used, for example 300 to 400 ℃.
In the impregnation section 123, the first thermoplastic resin is preferably impregnated in 40 to 250 parts by mass, more preferably 50 to 240 parts by mass, and even more preferably 60 to 220 parts by mass of the fibrous filler (the fiber bundles 11) in 100 parts by mass, depending on the characteristics required for the molded article, etc. If the amount of the fibrous filler is not less than the lower limit of the preferable range, the molded part is efficiently reinforced with the fibers. On the other hand, if it is not more than the upper limit of the preferable range, the fiber bundle can be easily opened and the first thermoplastic resin can be easily impregnated into the fiber bundle.
By changing the nozzle diameter of the die at the outlet of the impregnation section 123 with respect to the diameter of the fiber bundle 11, the mixing ratio of the first thermoplastic resin and the fibrous filler in the resin structure 13 can be adjusted.
In the cooling section 125, the resin structure 13 (the resin structure 13 obtained by impregnating and coating the fiber bundles with the melt) in the state heated by the impregnating section 123 is cooled to, for example, 50 to 150 ℃. The cooling time is not particularly limited, and is, for example, 3 to 30 seconds.
The resin structure 13 cooled by the cooling unit 125 is continuously extracted by the extracting unit 127, and sent to the next cutting unit 129.
In the cutting section 129, the cooled resin structure 13 is cut into a desired length to produce pellets 15. The cutting portion 129 includes, for example, a rotary blade.
A step of obtaining a resin structure:
while continuously feeding out the fiber bundle 11 formed by bundling a plurality of single fibers with a bundling agent from the fiber roving 10, the fiber bundle 11 is first heated and dried by the preheating part 121.
Then, while the dried fiber bundles 11 are supplied to the impregnation section 123, the molding material M melt-kneaded by the extruder 120 is fed from the supply port 123a, and the molding material M in a molten state is impregnated into the fiber bundles 11. Thus, the resin structure 13 obtained by impregnating and coating the fiber bundles with the melt was obtained. Then, the resin structure 13 in the state heated by the impregnation section 123 is cooled by the cooling section 125.
In the resin structure 13 obtained here, the fibers are arranged substantially parallel to the longitudinal direction of the resin structure 13.
The term "the fibers are arranged substantially parallel to the longitudinal direction of the resin structure" means that the angle formed by the longitudinal direction of the fibers and the longitudinal direction of the resin structure is substantially 0 °, specifically, the angle formed by the respective longitudinal directions of the fibers and the resin structure is-5 ° to 5 °.
A step of obtaining particles:
the cooled resin structure 13 is then extracted in a strand shape by the extracting unit 127, and sent to the cutting unit 129.
Then, the strand-like resin structure 13 is cut by a predetermined length in the longitudinal direction thereof by the cutting portion 129, and the pellets 15 are obtained.
The predetermined length of the particles 15 herein means a length of the particles 15 set according to the required performance of the molded article made of the particles 15. In the first particles obtained by the production method of the present embodiment, the length of the particles 15 is substantially the same as the length of the fibers arranged in the particles 15.
By "the length of the particles is substantially the same as the length of the fibers" is meant that the length weighted average fiber length of the fibers arranged in the particles is 95 to 105% of the length of the particles in the length direction.
As described above, the first particles (particles 15) in which the first thermoplastic resin is impregnated in the fibrous filler are produced.
The particles 15 are particles in which fibrous fillers are fixed by a first thermoplastic resin, and the fibrous fillers are aligned substantially parallel to the longitudinal direction of the particles. The length of the fibrous filler arranged in the particles 15 is substantially the same as the length of the particles. The length of the pellets 15 produced in the present embodiment depends on the required properties of the molded article made of the pellets 15, and is, for example, 3 to 50mm.
As described above, the fibrous filler is arranged substantially parallel to the longitudinal direction of the particles, and the length of the fibrous filler is substantially the same as the length of the particles, so that the fibrous filler remaining in the molded portion can be elongated when the molded portion is produced, and the fibrous filler has an effect in improving the heat resistance and alleviating the anisotropy of the molded portion.
The alignment direction of the fibrous fillers in the particles can be confirmed by observing a cross section of the particles cut in the longitudinal direction by a microscope.
The second particles are composed of a resin structure containing the second thermoplastic resin having a lower flow start temperature than the first particles, without containing the fibrous filler.
The second pellets are obtained by granulating a mixture of the second thermoplastic resin and other components as needed, for example, by a melt extrusion molding method or a melt compression molding method.
In this embodiment, the second thermoplastic resin is a resin having a flow start temperature lower than that of the first particles.
The difference in the flow start temperature between the second thermoplastic resin and the first thermoplastic resin is preferably 5 ℃ or higher, more preferably 5 to 40 ℃. Alternatively, the difference between the flow start temperature of the second thermoplastic resin and the first particles is preferably 5 ℃ or higher, more preferably 5 to 40 ℃.
By selecting the second thermoplastic resin as described above with respect to the first particles, the fibrous filler is appropriately dispersed as fiber bundles in the molded part, and further, by being present as fiber bundles during molding, fiber breakage is suppressed, and the fibrous filler in the molded article remains for a long period of time, so that the strength against collision load is easily exhibited.
After the first particles are frozen and crushed, the flow start temperature of the first particles can be obtained in the same manner as the above-described method for measuring the flow start temperature.
The second thermoplastic resin preferably has a melt viscosity of 5 to 500 Pa.s (measurement condition: aperture of nozzle 0.5mm, shear rate 1000 s) at a melt kneading temperature (plasticizing part) of a pellet mixture to be described later -1 ) Is a resin of (a).
Examples of the second thermoplastic resin include liquid crystal polyester resins, polypropylene, polyamide, polyesters other than liquid crystal polyester resins, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherketone, polyetheretherketone, polycarbonate, polyphenylene oxide, and polyetherimide. Among them, a liquid crystal polyester resin is preferably used.
The second thermoplastic resin may be used alone or in combination of two or more.
The first particles are mixed with the second particles, thereby obtaining a particle mixture.
In the mixing ratio (mass ratio) of the first particles and the second particles, the first particles and the second particles are preferably mixed so that the thermoplastic resin is 40 to 70 parts by mass and the fibrous filler is 30 to 60 parts by mass when forming the molded part.
For example, the mixing ratio (mass ratio) of the two is preferably 50 to 90 parts by mass of the first particles, 10 to 50 parts by mass of the second particles, more preferably 55 to 85 parts by mass of the first particles, 15 to 45 parts by mass of the second particles, still more preferably 55 to 80 parts by mass of the first particles, and 20 to 45 parts by mass of the second particles.
The first particles and the second particles may be fed into a molding machine separately and mixed in the molding machine, or a mixture in which both particles are mixed in advance may be prepared. Alternatively, the first particles and the second particles may be used in a form in which the second particles are coated on the surface of the first particles.
When the impact absorbing member is molded using the obtained pellet mixture, for example, the melt kneading temperature (plasticizing part) of the pellets is preferably higher than the flow start temperature of the second thermoplastic resin and equal to or lower than the flow start temperature of the first thermoplastic resin or the first pellets. Specifically, the melt kneading temperature (plasticizing unit) is preferably 260 to 340 ℃, more preferably 280 to 320 ℃, and even more preferably 290 to 310 ℃. The metering section or plunger section is preferably 280 to 400 ℃, more preferably 290 to 380 ℃, and even more preferably 300 to 370 ℃. By controlling as described above, the long fibers in the molding part are easily realized.
(vehicle)
In the vehicle according to the aspect of the present invention, the impact absorbing member according to the aspect of the present invention is attached to at least one of the front, rear, and side portions of the vehicle.
Examples of the vehicle include a bicycle, a motorcycle, a quadricycle, and an electric car.
For example, a structural member as shown in fig. 1, that is, a structural member in which the impact absorbing member 200 is provided between the front side member 400 (frame) and the bumper 300 is attached to the front portion of the motorcycle.
According to the vehicle of the present embodiment, since the impact absorbing member of the above embodiment is used, both the fuel consumption reduction by weight saving and the impact energy absorbing performance further improved to improve the collision safety can be realized.
While the preferred embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to these examples. The shapes, combinations, and the like of the respective constituent members shown in the above examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.
Examples
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.
< preparation of resin Material >
As the thermoplastic resin, liquid crystal polyester resin, polypropylene, nylon 6 are used. In the present specification, the liquid crystal polyester resins are sometimes abbreviated as LCP and polypropylene as PP, respectively.
As the fibrous filler, glass fiber and carbon fiber are used. In the present specification, glass fibers may be abbreviated as GF and carbon fibers may be abbreviated as CF, respectively.
The preparation of the resin material is carried out by mixing these thermoplastic resins with fibrous fillers. Specifically, pure particles obtained by processing a liquid crystal polyester resin, resin particles obtained by impregnating glass fibers with a liquid crystal polyester resin, resin particles obtained by impregnating carbon fibers with polypropylene, and resin particles obtained by impregnating carbon fibers with nylon 6 were produced, respectively.
Production of pure substance particles (1)
Pure substance particles (1) (LCP 1) were produced as follows.
To a reactor equipped with a stirrer, a torque meter, a nitrogen inlet tube, a thermometer and a reflux condenser, p-hydroxybenzoic acid (994.5 g,7.2 mol), 4' -dihydroxybiphenyl (446.9 g,2.4 mol), terephthalic acid (299.0 g,1.8 mol), isophthalic acid (99.7 g,0.6 mol) and acetic anhydride (1347.6 g,13.2 mol) and 1-methylimidazole (0.9 g) were charged, and the inside of the reactor was sufficiently replaced with nitrogen. Then, the temperature was raised from room temperature to 150℃under a nitrogen gas stream for 30 minutes, and the mixture was kept at 150℃and refluxed for 1 hour. Then, 1-methylimidazole (0.9 g) was added thereto, and the temperature was raised from 150℃to 320℃over 2 hours and 50 minutes while distilling off acetic acid and unreacted acetic anhydride as by-products, so that the reaction was completed at the point when a rise in torque was observed, and the content was taken out and cooled to room temperature. The solid matter obtained was pulverized into particles having a particle size of about 0.1 to 1mm by a pulverizer, and then heated from room temperature to 250℃for 1 hour, heated from 250℃to 285℃for 5 hours, and kept at 285℃for 3 hours under a nitrogen atmosphere, whereby solid-phase polymerization was carried out. After solid-phase polymerization, the mixture was cooled to obtain a powdery liquid-crystalline polyester resin.
The liquid-crystalline polyester resin obtained here had 60 mol% of Ar with respect to the total amount of all the repeating units 1 Repeating unit (1) being 1, 4-phenylene, 15 mol% Ar 2 Repeating unit (2) being 1, 4-phenylene, 5 mol% Ar 2 Repeating unit (2) being 1, 3-phenylene and 20 mol% Ar 3 Is a repeating unit (3) of 4,4' -biphenylene group, and the flow initiation temperature thereof is 327 ℃.
The obtained powdery liquid crystal polyester resin was pelletized by a biaxial extruder (PMT 47, manufactured by IKG corporation) at a barrel temperature of 320 ℃ to obtain LCP1. The flow onset temperature of the resulting LCP1 was 316 ℃.
Production of pure substance particles (2)
Pure substance particles (2) (LCP 2) were produced as follows.
To a reactor equipped with a stirrer, a torque meter, a nitrogen inlet tube, a thermometer and a reflux condenser, p-hydroxybenzoic acid (994.5 g,7.2 mol), 4' -dihydroxybiphenyl (446.9 g,2.4 mol), terephthalic acid (239.2 g,1.44 mol), isophthalic acid (159.5 g,0.96 mol) and acetic anhydride (1347.6 g,13.2 mol) were charged, and 1-methylimidazole (0.9 g) was added and the inside of the reactor was sufficiently replaced with nitrogen. Then, the temperature was raised from room temperature to 150℃under a nitrogen gas stream for 30 minutes, and the mixture was kept at 150℃and refluxed for 1 hour. Then, 0.9g of 1-methylimidazole was added thereto, and the temperature was raised from 150℃to 320℃over 2 hours and 50 minutes while removing acetic acid and unreacted acetic anhydride by distillation, so that the reaction was completed at the point when a rise in torque was observed, and the content was taken out and cooled to room temperature. The solid matter obtained was pulverized into particles having a particle size of about 0.1 to 1mm by a pulverizer, and then heated from room temperature to 220℃for 1 hour, heated from 220℃to 240℃for 0.5 hour, and kept at 240℃for 10 hours under a nitrogen atmosphere, whereby solid-phase polymerization was carried out. After solid-phase polymerization, the mixture was cooled to obtain a powdery liquid-crystalline polyester resin.
The liquid-crystalline polyester resin obtained here had 60 mol% of Ar with respect to the total amount of all the repeating units 1 Repeating unit (1) being 1, 4-phenylene, 12 mol% Ar 2 Repeating unit (2) being 1, 4-phenylene, 8 mol% Ar 2 Repeating unit (2) being 1, 3-phenylene and 20 mol% Ar 3 The repeating unit (3) being a 4,4' -biphenylene group, and the flow initiation temperature thereof was 291 ℃.
The obtained powdery liquid crystal polyester resin was pelletized by a biaxial extruder (PMT 47, manufactured by IKG corporation) at a barrel temperature of 290 ℃ to obtain LCP2. The flow onset temperature of the resulting LCP2 was 284 ℃.
Production of resin particles 1
Resin pellets 1 were produced in which glass fibers were impregnated with a liquid crystal polyester resin.
The resin particles 1 were produced as described below using the same production apparatus as the one shown in fig. 5.
As the extruder 120, a GTS-40 extruder (manufactured by Plastic engineering institute, inc.) was used. The belt extractor was manufactured by Eimer corporation (IMECS CO., LTD.) using EBD-1500A. The following glass fibers were used as the fibrous filler.
Glass fiber (GF 1): glass fiber roving (E glass, number average fiber diameter 17 μm, fineness 1200g/1000m, manufactured by Nitro Kagaku Co., ltd.)
As the pure material particles, the above LCP1 and LCP2 were used.
Resin particles 1 having a GF1 content of 95 parts by mass were produced as described below with respect to 100 parts by mass of the total of LCP1 and LCP2 (85 parts by mass of LCP1 and 15 parts by mass of LCP 2).
A step of obtaining a resin structure:
by operating the belt type drawing machine (drawing unit 127), while continuously feeding the glass fiber bundles 11 from the glass fiber roving 10 of GF1 at a drawing speed of 10 m/min, the glass fiber bundles 11 are first heated to 150 ℃ by the preheating unit 121 and dried.
Then, while the dried glass fiber bundles 11 are supplied to a die (impregnation section 123) attached to the front end of the extruder 120, LCP1 and LCP2 in molten state are fed from the supply port 123a by the extruder 120. The LCP1 and LCP2 were melted at 370 ℃ in a mold (impregnating unit 123) and impregnated into the glass fiber bundles 11, and the strand diameters were adjusted by a die having a nozzle diameter of 1.5mm at the outlet of the mold (impregnating unit 123), whereby a resin structure 13 having a GF1 content of 95 parts by mass relative to 100 parts by mass (85 parts by mass for LCP1 and 15 parts by mass for LCP 2) in total was obtained.
In the resin structure 13 obtained here, the glass fibers are arranged substantially parallel to the longitudinal direction of the first liquid crystal polyester resin layer.
Then, the resin structure 13 in a heated state in the mold (impregnation section 123) is cooled to 150 ℃ or lower by the cooling section 125.
A step of obtaining particles:
then, the cooled resin structure 13 is extracted in a strand shape by the belt extractor (extraction unit 127), sent to a granulator (cutting unit 129), and cut along the longitudinal direction thereof by a predetermined length (12 mm), thereby obtaining cylindrical resin pellets 1 (pellets 15).
Production of resin particles 2
Resin pellets 2 having a GF1 content of 216 parts by mass (85 parts by mass of LCP1 and 15 parts by mass of LCP 2) were obtained in the same manner as resin pellets 1 except that a die having a nozzle diameter of 1.1mm was used.
Production of resin particles 3
As the fibrous filler, glass fiber (GF 2): glass fiber roving (E glass, number average fiber diameter 10 μm, fineness 1400g/1000m, manufactured by Nitro Kagaku Co., ltd.).
Resin particles 3 having a GF2 content of 60 parts by mass based on 100 parts by mass of the total of LCP1 and LCP2 (85 parts by mass of LCP1 and 15 parts by mass of LCP 2) were obtained in the same manner as resin particles 1 except that GF2 was used instead of GF1 and a die having a nozzle diameter of 1.8mm was used.
Production of resin particles 4
Resin particles 4 having a GF2 content of 102 parts by mass based on 100 parts by mass of the total of LCP1 and LCP2 (85 parts by mass of LCP1 and 15 parts by mass of LCP 2) were obtained in the same manner as resin particles 1 except that GF2 was used instead of GF1 and a die having a nozzle diameter of 1.5mm was used.
Production of resin particles 5
Resin particles 5 having a GF2 content of 169 parts by mass (85 parts by mass of LCP1 and 15 parts by mass of LCP 2) based on 100 parts by mass of the total of LCP1 and LCP2 were obtained in the same manner as resin particles 1 except that GF2 was used instead of GF1 and a die having a nozzle diameter of 1.3mm was used.
Production of resin particles 6
Resin particles 6 having a GF2 content of 60 parts by mass based on 100 parts by mass of the total of LCP1 and LCP2 (75 parts by mass of LCP1 and 25 parts by mass of LCP 2) were obtained in the same manner as resin particles 1 except that GF2 was used instead of GF1 and a die having a nozzle diameter of 1.8mm was used.
LCP staple fiber GF35 mass% particles
As resin particles obtained by impregnating glass fibers with a liquid crystal polyester resin, the trade name sumika super E6007 lhfz (manufactured by sumitomo chemical corporation) was used.
PP long fiber GF40 mass% particle
As the resin particles obtained by impregnating glass fibers with polypropylene (PP), the trade name SUMISTRAN PG4003-3 (manufactured by Sumitomo chemical Co., ltd.) was used.
Production of PA6 Long fiber CF30 mass% particles
Resin particles were produced in which nylon 6 (PA 6) was impregnated in carbon fibers.
As the pure material particles, PA6 (UBE nylon 1013B, manufactured by Yu Xingxing Co., ltd.) was used. As the fibrous filler, carbon fibers (CF 1): carbon fiber roving (trade name "TR50S15L", number average fiber diameter 7 μm, fineness 1000g/1000m, manufactured by Mitsubishi chemical Co., ltd.).
PA6 was melted at 280 ℃ in a die (impregnation section 123) using CF1 instead of GF1, impregnated with carbon fiber bundle 11, and a die nozzle having a nozzle diameter of 2.0mm was used at the outlet of the die (impregnation section 123), and PA6 long fiber CF30 mass% pellets having a CF1 content of 43 mass parts per 100 mass parts of PA6 were produced in the same manner as resin pellets 1.
< manufacturing of shock absorbing Member >
Example 1 and comparative example 1
A step of obtaining a particle mixture:
LCP2 as the pure material particles prepared above and resin particles 1 were mixed in the proportions described in table 1 to obtain a resin composition (1) composed of the particle mixture.
A step of injection molding the resin composition:
the resin composition (1) was charged into a hopper of an injection molding machine TR450EH3 (Sha Dike).
The impact absorbing member was produced by melt-kneading at a molding temperature of 300℃in the plasticizing unit and 360℃in the plunger unit, and injecting the molded portion having a main body having a honeycomb structure of the same form as that shown in FIG. 2 into a mold having a honeycomb structure under other molding conditions.
Other molding conditions: back pressure is 1MPa, injection speed is 200mm/s, die temperature is 80 ℃, pressure is maintained at 70MPa, and pressure maintaining time is 5 seconds.
The honeycomb structure provided in the main body portion was composed of 32 cylindrical cells having a height of 80mm, an opening surface of a substantially regular hexagonal shape, and a radius of curvature of each apex of 2mm in plan view, wherein the thickness of the flange portion in the cylindrical cells was 3mm, the cell inner diameter of the end face on the flange portion side was 12.0mm, the cell inner diameter of the end face (opening surface) on the opposite side to the flange portion was 13.0mm in example 1, and the cell inner diameter of the end face (opening surface) on the opposite side to the flange portion was 12.5mm in comparative example 1. In addition, the thickness of the cell wall of the end face on the flange side in the cylindrical cell was 2.0mm, the thickness of the cell wall of the end face on the opposite side to the flange (opening face) was 1.0mm in example 1 (the average thickness of the cell wall from the end face on the flange side to the end face on the opposite side to the flange (opening face) was 1.5mm, and the thickness of the cell wall of the end face on the opposite side to the flange (average thickness of the cell wall from the end face on the flange side to the end face on the opposite side to the flange (opening face) was 1.75 mm) in comparative example 1.
Example 2 and comparative example 2
A step of obtaining a particle mixture:
LCP2 as the pure material particles prepared above was mixed with resin particles 3 in the proportions described in table 1 to obtain a resin composition (3) composed of the particle mixture.
A step of injection molding the resin composition:
an impact absorbing member was produced by molding an injection molded part in the same manner as in example 1 described above in example 2 and in the same manner as in comparative example 1 described above in comparative example 2, except that the resin composition (3) was used instead of the resin composition (1).
Example 3, comparative example 3
A step of obtaining a particle mixture:
LCP2 as the pure material particles prepared above was mixed with resin particles 4 in the proportions described in table 1 to obtain a resin composition (4) composed of the particle mixture.
A step of injection molding the resin composition:
an impact absorbing member was produced in the same manner as in example 1 described above in example 3 and in the same manner as in comparative example 1 described above in comparative example 3 by molding an injection molded part except that the resin composition (4) was used instead of the resin composition (1).
Example 4
The injection-molded part was molded in the same manner as in example 1 to produce an impact absorbing member.
Example 5
An impact absorbing member was produced by molding an injection molded part in the same manner as in example 1 above, except that the resin composition (2) composed of a particle mixture in which LCP2 as a pure material particle and resin particles 2 were mixed in the proportions described in table 1 was used.
Example 6
The injection-molded part was molded in the same manner as in example 3 to produce an impact absorbing member.
Example 7
An impact absorbing member was produced by molding an injection molded part in the same manner as in example 1 above, except that the resin composition (5) composed of a mixture of particles in which LCP1 as a pure material particle and resin particles 5 were mixed in the proportions shown in table 1 was used, and the temperature of the plasticizing part was changed to 330 ℃ and the temperature of the plunger part was changed to 340 ℃ in accordance with the mixture.
Example 8
An injection molded part was molded in the same manner as in example 1 above except that the temperature of the plasticized part was changed to 350 ℃ in response to the use of 35 mass% particles of LCP staple fiber GF, and an impact absorbing member was produced.
Example 9
An injection molded part was molded in the same manner as in example 1 above except that the PP long fiber GF40 mass% pellets were used, and the temperature of the plasticizing part was changed to 250 ℃, the temperature of the plunger part was changed to 250 ℃, and the mold temperature was changed to 50 ℃, in accordance with this, to produce an impact absorbing member.
Example 10
An injection molded part was molded in the same manner as in example 1 above except that the PA6 long fiber CF30 mass% pellets were used, and the temperature of the plasticizing part was changed to 270 ℃, the temperature of the plunger part was changed to 270 ℃, and the mold temperature was changed to 70 ℃ in response thereto, to produce an impact absorbing member.
Example 11
The injection-molded part was molded in the same manner as in example 7 to produce an impact absorbing member.
Example 12
The injection-molded part was molded in the same manner as in example 9 to produce an impact absorbing member.
Example 13
The injection-molded part was molded in the same manner as in example 10 to produce an impact absorbing member.
Example 14
A step of obtaining a particle mixture:
LCP2 as the pure material particles prepared above was mixed with resin particles 6 in the proportions described in table 1 to obtain a resin composition (6) composed of the particle mixture.
A step of injection molding the resin composition:
an impact absorbing member was produced by molding an injection molded part in the same manner as in example 1 above, except that the resin composition (6) was used instead of the resin composition (1), and the temperature of the plasticized part was changed to 350 ℃.
Example 15
An impact absorbing member was produced by molding an injection molded part in the same manner as in example 14, except that a mold having the following shape (honeycomb structure) was used.
The honeycomb structure provided in the main body was composed of 32 cylindrical cells each having a height of 80mm, an opening surface of a substantially regular hexagonal shape, and a radius of curvature of each apex of 2mm in plan view, the thickness of the flange portion in the cylindrical cells was 3mm, the cell inner diameter of the end face on the flange portion side was 12.3mm, and the cell inner diameter of the end face (opening surface) on the opposite side to the flange portion was 13.3mm. The thickness of the cell wall of the end face on the flange side in the tubular cell was 1.7mm, and the thickness of the cell wall of the end face (opening face) on the opposite side from the flange was 0.7mm (the average thickness of the cell wall from the end face on the flange side to the end face (opening face) on the opposite side from the flange was 1.2 mm).
Example 16
An impact absorbing member was produced by molding an injection molded part in the same manner as in example 14 above, except that a mold having a honeycomb structure of the following shape was used.
The honeycomb structure provided in the main body was constituted by 56 cylindrical cells each having a height of 80mm, an opening surface of a substantially regular hexagonal shape, and a radius of curvature of each apex of 2mm in plan view, a thickness of a flange portion in the cylindrical cells was 3mm, an inner diameter of the cell at an end face on the flange portion side was 7.6mm, and an inner diameter of the cell at an end face (opening surface) on the opposite side to the flange portion was 8.6mm. The thickness of the cell wall of the end face on the flange side in the tubular cell was 1.7mm, and the thickness of the cell wall of the end face (opening face) on the opposite side from the flange was 0.7mm (the average thickness of the cell wall from the end face on the flange side to the end face (opening face) on the opposite side from the flange was 1.2 mm).
[ method for calculating thickness gradient of cell wall ]
For each example of the impact absorbing member, the thickness gradient of the cell wall between the tubular cells in the injection molding portion was obtained by the following procedure. The values are shown in tables 2 to 5.
Step 1) a center axis a passing through the center of gravity of one end face and the center of gravity of the other end face in the first cylindrical unit having a height of 80mm is set.
Step 2) setting arbitrary two surfaces b and c perpendicular to the center axis a at positions of 5mm and 75mm from the first cylindrical unit of the flange portion, and setting the distance between the two surfaces b and c to be 70mm.
Step 3) sets the thickness of the cell wall at the position (opening surface side) where the cell wall between the first tubular cell and the second tubular cell adjacent thereto intersects with the surface b to t1mm.
Step 4) the thickness of the cell wall at the position (flange portion side) where the cell wall between the first tubular cell and the second tubular cell adjacent thereto intersects the surface c is set to t2mm.
Step 5) calculate |t2-t1|/h, h=70 as the thickness gradient of the cell wall.
[ measurement of the Length-weighted average fiber Length of fibrous Filler contained in injection Molding portion ]
The length-weighted average fiber length of each of the glass fibers and the carbon fibers contained in the injection molding section was obtained by the following procedure.
Step (1): the maximum length (length of the longest part in the projection plane of the test piece) cut out from the outermost wall of the main body part is 20mm or more, the maximum vertical length (length of the longest part in the direction of 90 degrees from the maximum length) is 20mm or more, and the projection area of the test piece is 200mm 2 The test piece above.
Step (2): the test piece was heated at 600℃for 4 hours in the case of glass fiber and at 500℃for 3 hours in the case of carbon fiber using a muffle furnace, and the resin component was removed.
Step (3): in step (2), a substance (fiber only) from which a resin component was removed from the cut test piece was dispersed in 1000mL of an aqueous solution containing 0.05% by volume of a surfactant (manufactured by Micro90INTERNATIONAL PRODUCTS CORPORATION Co.) to prepare a dispersion.
Step (4): 100mL of the dispersion was taken out, and diluted to 10-fold with pure water. 50mL of the diluted dispersion was taken out and dispersed in a culture dish, and then the fibers dispersed in the culture dish were observed by a microscope (20 Xmagnification of VH-ZST (manufactured by KEYENCE Co.). 10 images were taken for each sample in such a manner that the photographing areas did not overlap.
Step (5): the length of all fibers present in the 1-image taken was determined by means of a microscopic measuring tool. The bent fibers were measured by multipoint-to-multipoint measurement. The same procedure was sequentially performed using 10 images taken until the total number of fibers measured exceeded 500, and the fiber length was measured.
Step (6): from the fiber length of the fibers measured in step (5), the length weighted average fiber length (lm) of the fibrous filler contained in the injection molding section is obtained (Σni > 500).
lm＝(Σli 2 ×ni)/(Σli×ni)
li: fiber length of fibrous filler
ni: number of fibrous fillers of fiber length li
Table 1 shows the resin materials and molding conditions used in manufacturing the impact absorbing members of each example.
TABLE 1
< evaluation (1) >
The following drop weight impact test was performed on the impact absorbing members of each example, and the maximum load, the average load, the impact energy absorption amount per unit weight, and the impact energy absorption efficiency were obtained. These results are shown in tables 2 and 3.
The content of the fibers contained in the injection molding part is also set; the thickness t1 (opening face side) of the cell wall, t2 (flange portion side), and the thickness gradient |t2-t1|/h of the cell wall in the honeycomb structure; the length-weighted average fiber length of the fibers contained in the injection molding part is shown in tables 2 and 3.
The total volume, total weight, and effective volume of the injection molded part are shown in tables 2 and 3. The effective volume of the injection molded part indicates the volume of the injection molded part existing in the effective displacement region of the ram (the distance from the ram initial position (upper surface of the test body 990 provided on the test stand 910) to the ram stopper portion) at the time of the drop impact test.
Drop hammer impact test
Fig. 6 is a diagram showing an apparatus for drop hammer impact test.
As shown in fig. 6, the apparatus 900 includes a test bed 910, a load meter 920 that supports the test bed 910 at the lower side, displacement meters 930a, 930b that are disposed separately on the left and right sides of the load meter 920, a ram 940 that drops from above the test bed 910, and a ram stopper 950 that prevents the ram 940 from dropping.
In fig. 6, a test body 990 is provided on the test stand 910. The falling ram 940 contacts the upper surface of the test body 990.
The drop hammer impact test method comprises the following steps:
the shock absorbing members of each example were each a test piece 990.
Using the apparatus 900 shown in fig. 6, the ram 940 was allowed to fall freely with respect to the test body 990 on the load meter 920 and an impact was applied. Then, the load [ kN ] applied to the test body 990 at this time and the displacement [ mm ] of the upper surface of the test body 990 were measured.
Conditions of drop hammer impact test:
set collision speed 30km/h
Hammer body weight 300kg
Drop height 3.54m
The effective displacement (distance from the initial position of the ram (upper surface of the ram 990 provided on the test bed 910) to the ram stopper) was 55mm in the case where the inclination angle of the test bed 910 was 0 °; the inclination angle of the test stand 910 was 30mm in the case of 15 °.
The using device comprises:
the load cell 920 uses the model "CLP-30BS", equipment manufacturer "TOKYO SOKKI KENKYUJO co.ltd".
The displacement meters 930a, 930b use model "LK-G505 (North side: no.1271178, south side: no. 1261015)", equipment manufacturer "KEYENCE CORPORATION".
The recording device was used with model "DIS-5200A" and equipment manufacturer "KYOWA ELECTRONIC INSTRUMENTS CO.LTD".
The high-speed photographic apparatus used the model "memreecam GX-1", apparatus manufacturer "NAC Image Technology inc.
The analog filters of the load meter 920 and displacement meters 930a, 930b were 10kHz. The sampling frequency of the recording device was 50kHz, and the analog filter was 10kHz.
In order to confirm the behavior of the test body, photographing was performed at 5000fps using a high-speed photographing apparatus.
[ measurement of impact energy absorption amount ]
Fig. 7 is a graph showing the results of drop impact tests (the inclination angle of the test stand 910 is 0 ° and the effective displacement is 55 mm) for the respective impact absorbing members of example 1 and comparative example 1.
The left side of the vertical axis represents the load (kN) applied to the test body 990, and the right side represents the absorbed energy (kJ).
The horizontal axis represents displacement [ mm ] of the upper surface of the test body 990 (the lower surface of the hammer 940 that contacts the upper surface of the test body 990). The initial position of the upper surface of the test piece 990 was set to 0mm.
Based on the results of the graph shown in fig. 7, the impact energy absorption amounts at the displacements of 0 to 55mm were measured for the impact absorbing members of the respective examples.
From the results of the graph, the maximum load, the average load, the impact energy absorption amount per unit weight, and the impact energy absorption efficiency were obtained.
The impact absorbing members of examples 2 to 3, comparative examples 2 to 3 and examples 14 to 16 were also measured in the same manner.
The impact energy absorption per unit weight was calculated as follows. The larger this value means the higher the impact energy absorbing performance.
Impact energy absorption per unit weight (J/g)
Impact energy absorption amount up to effective displacement/mass of damaged forming material up to effective displacement
The impact energy absorption efficiency was calculated as follows. The larger this value means that the impact energy absorption does not generate excessive maximum load at all times.
Impact energy absorption efficiency
Actual impact energy absorption amount (kJ)/(maximum load (kN) ×effective displacement (m))
TABLE 2
From the results of table 2, in the comparison of example 1 and comparative example 1, the comparison of example 2 and comparative example 2, and the comparison of example 3 and comparative example 3, it was confirmed that the impact energy absorbing performance was further improved for the impact absorbing member of the example in which the cylindrical cells were arranged via the cell walls whose thickness gradient (|t2-t1|/h) satisfies the relationship of formula (G) as compared to the impact absorbing member of the comparative example.
TABLE 3 Table 3
From the results of table 3, it was confirmed that the impact energy absorbing performance of the impact absorbing members of examples 14 to 16, in which the cylindrical units were arranged via the unit walls whose thickness gradient (|t2-t1|/h) satisfied the relationship of formula (G), was all high.
In particular, it was confirmed that the impact energy absorption amount per unit weight was large in the impact absorbing members of examples 14 to 16.
It was also confirmed that the impact energy absorption per unit weight increased in the order of example 14, example 15, and example 16. This is considered to be the effect of thinning the cell wall according to the comparison of example 14 with example 15. In addition, the comparison between example 15 and example 16 is considered to be an effect of reducing the inner diameter of the cell.
< evaluation (2) >
The drop impact test was performed in the same manner as in (1) > except that the impact absorbing members of examples 4 to 10 were each set to the test body 990 and the test body 990 was set to the test stand 910 at an inclination angle of 15 °. The effective displacement was set to 30mm.
Fig. 8 is a diagram showing a state of a test body 990 mounted on the test stand 910 when the drop impact test in the evaluation (2) is performed. In fig. 8, the test body 990 is disposed at an inclination angle of 15 ° with respect to the test bed 910.
The impact energy absorption amount was measured at a displacement of 0 to 30mm for each example of the impact absorbing member. Further, from the result, the impact energy absorption per unit weight was obtained. Further, the angle dependence was evaluated according to the following formula. These results are shown in Table 4.
Angle dependence = impact energy absorption per unit weight of 15 ° of tilt angle/impact energy absorption per unit weight of 0 ° of tilt angle
The larger the value, the lower the angle dependence on the impact, the lower the impact angle has on the impact energy absorbing performance.
The drop impact test (the inclination angle of the test bed 910 was 0 ° and the effective displacement was 55 mm) was performed in the same manner as in < evaluation (1) > except that the impact absorbing members of examples 4 to 10 were each test body 990, and the impact energy absorption per unit weight at the inclination angle of 0 ° was obtained.
The content of the fibers contained in the injection molding part is also set; the thickness t1 (opening face side) of the cell wall, t2 (flange portion side), and the thickness gradient |t2-t1|/h of the cell wall in the honeycomb structure; the length-weighted average fiber length of the fibers contained in the injection molding part is shown in table 4.
The total volume, total weight, and effective volume of the injection molded part are shown in table 4. The effective volume of the injection molded part indicates the volume of the injection molded part existing in the effective displacement region of the ram (the distance from the ram initial position (upper surface of the test body 990 provided on the test stand 910) to the ram stopper portion) at the time of the drop impact test.
TABLE 4 Table 4
From the results of table 4, it was confirmed that the impact absorbing members of examples 4 to 7, 9 and 10 had lower angular dependence on impact than the impact absorbing member of example 8, and the impact energy absorbing performance was further improved.
It is assumed that the result is mainly based on the length-weighted average fiber length of the fibrous filler in the molding section.
< evaluation (3) >
The impact absorbing members of examples 11 to 13 were stored in a constant temperature and humidity tank at a temperature of 45℃and a relative humidity of 98% RH for 7 days. The water absorption rate of the impact absorbing member after storage was measured under the following measurement conditions. The results are shown in Table 5.
Measurement conditions of Water absorption
The device comprises: constant temperature and humidity tank FH06C (Etac Engineering co., ltd.)
Moisture absorption conditions: 45 ℃ x 98%RH x 168 hours
Weight measurement of molded article in absolute dry state: the molded article after molding was immediately cooled in an aluminum bag, and accurately measured to 0.001g by a precision balance.
Weight measurement of the molded article after moisture absorption: taken out of the constant temperature and humidity tank and accurately measured to 0.001g by a precision balance.
The drop impact test (effective displacement 55 mm) was performed in the same manner as in < evaluation (1) > except that the impact absorbing members of examples 11 to 13 before and after storage were each test piece 990 and the test piece 990 was provided on the test bed 910.
The impact energy absorption amount was measured at a displacement of 0 to 55mm for each example of the impact absorbing member. Further, from the result, the impact energy absorption per unit weight was obtained. Further, the water absorption dependence was evaluated according to the following formula. These results are shown in Table 5.
Water absorption dependency = impact energy absorption per unit weight after absorption/impact energy absorption per unit weight before absorption
The larger the value, the lower the water absorption dependence, and the smaller the influence of the moisture absorption on the impact energy absorption performance.
The content of the fibers contained in the injection molding part is also set; the thickness t1 (opening face side) of the cell wall, t2 (flange portion side), and the thickness gradient |t2-t1|/h of the cell wall in the honeycomb structure; the length-weighted average fiber length of the fibers contained in the injection molding part is shown in table 5.
Table 5 shows the total volume of the injection molded part, the total weight before moisture absorption, and the effective volume. The effective volume of the injection molded part indicates the volume of the injection molded part existing in the effective displacement region of the ram (the distance from the ram initial position (upper surface of the test body 990 provided on the test stand 910) to the ram stopper portion) at the time of the drop impact test.
TABLE 5
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From the results of table 5, it was confirmed that the impact absorbing member of example 11 had no change in the amount of impact energy absorbed per unit weight before and after moisture absorption, and had low water absorption dependence.
The result is presumed to be because a liquid crystal polyester resin is used as the thermoplastic resin.
Description of the reference numerals
100 manufacturing a device; 101-109 conveying rollers; 120 extruder; 121 a preheating part; 123 impregnation part; 125 cooling sections; 127 extraction part; 129 cut-off part; 200 an impact absorbing member; 300 bumpers; 400 front side members; 500 an impact absorbing member; 510 a main body portion; 512 cylindrical units; 514 cell walls; 520 flange portion; 530 an injection molding section; 900 devices; 910 a test stand; 920 load meter; 930a displacement meter; 930b displacement meter; 940 hammer body; 950 hammer block stop; 990 test body.

Claims (6)

1. An impact absorbing member comprising a molded part comprising a thermoplastic resin, characterized in that,
the molding part comprises a main body part having a honeycomb structure filled with a plurality of cylindrical cells,
part or all of the cylindrical cells constituting the honeycomb structure are arranged via cell walls satisfying the relationship of the following formula (G) as |t2-t1|/h, which is a thickness gradient obtained by the following [ method of calculating a thickness gradient of cell walls ],
[ method for calculating thickness gradient of cell wall ]
Step 1) setting a center axis a passing through the center of gravity of one end face and the center of gravity of the other end face in the first cylindrical unit having a height H,
step 2) setting arbitrary two surfaces b and c perpendicular to the central axis a within the range of the height H of the first cylindrical unit, setting the distance between the two surfaces b and c as H, wherein the unit of H is mm,0 < H < H,
step 3) setting the thickness of the cell wall at the position where the cell wall between the first cylindrical cell and the second cylindrical cell adjacent thereto intersects with the face b to be t1, the unit of t1 being mm,
step 4) setting the thickness of the cell wall at the position where the cell wall between the first cylindrical cell and the second cylindrical cell adjacent thereto intersects with the face c to be t2, the unit of t2 being mm,
step 5) calculating |t2-t1|/h as the thickness gradient of the cell wall.
2. The impact-absorbing member of claim 1, wherein the molding portion is an injection molding portion.
3. The impact-absorbing member of claim 1, wherein the molding portion further contains a fibrous filler.
4. The impact absorbing member according to claim 3, wherein the fibrous filler contained in the molding part has a length-weighted average fiber length of 0.5mm or more.
5. The impact-absorbing member of claim 1, wherein the thermoplastic resin is a liquid-crystalline polyester resin.
6. A vehicle in which the impact absorbing member of any one of claims 1 to 5 is mounted to at least one of a front, a rear, and a side of the vehicle.
CN202280035298.2A 2021-05-19 2022-05-13 Impact absorbing member and vehicle Pending CN117377836A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2021-084347 2021-05-19
JP2021-214975 2021-12-28
JP2021214975 2021-12-28
PCT/JP2022/020212 WO2022244698A1 (en) 2021-05-19 2022-05-13 Shock-absorbing member and vehicle

Publications (1)

Publication Number Publication Date
CN117377836A true CN117377836A (en) 2024-01-09

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Family Applications (1)

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CN202280035298.2A Pending CN117377836A (en) 2021-05-19 2022-05-13 Impact absorbing member and vehicle

Country Status (1)

Country Link
CN (1) CN117377836A (en)

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