JP2000065114A - Impact absorbing part, manufacture therefor and use therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a lightweight impact absorbing part excellent in impact resistance while maintaining rigidity, and to efficiently manufacture the impact absorbing part by arranging a soft material at least in the vicinity of a starting point of rupture of the impact absorbing part composed of a hard material and integrally forming both. SOLUTION: An impact absorbing part is composed of a soft material 2, the soft material 2 is arranged at least in the vicinity of a starting point of rupture, and both are integrally formed. The drawing is one example of this impact absorbing part showing a shape of partially arranging the soft material 2. When an impact load 4 is applied in a state of supporting the end part of the impact absorbing part composed of a hard material 1 such as (a) by the fixing part 3, the opposite side of the impact surface becomes a starting point 6 such as (b). The hardly-cracking soft material 2 is arranged in this part, and the hard material 1 and the soft material 2 are integrally formed to improve impact resistance of the impact absorbing part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-performance shock-absorbing component comprising a combination of a hard material and a soft material, a method for producing the same, and an automobile component comprising the shock-absorbing component.

[0002]

2. Description of the Related Art Impact absorbing parts used in automobiles and the like are:
In recent years, the number of parts has been increased for the purpose of improving the safety level, and plastics have been increasingly used in terms of weight reduction and cost.

[0003] These components are required to have a structure that can reduce the weight and improve the strength. In terms of the structure, ribs that can improve the strength without increasing the weight, such as increasing the wall thickness. JP-A-8-31031
No. 7, for example.

[0004] Each of these parts is subjected to an impact test prescribed in the standard to confirm whether or not the required performance is satisfied. In many cases where the required performance is not satisfied, the rigidity of the shock absorbing part is reduced. The reason for this is that it is low and the shock-absorbing parts are destroyed and cannot absorb enough shock.

[0005] For this reason, in terms of the material, it is required to improve both the rigidity and the impact resistance. Therefore, it is known that, for example, in the case of polypropylene, the performance of the material can be improved by compounding by adding a filler such as rubber or talc.

[0006]

However, there is a limit in realizing high performance only in terms of material for high performance requirements, and particularly high performance materials are expensive and lead to high cost of parts. Met. An object of the present invention is to provide an inexpensive lightweight shock absorbing component having excellent shock resistance while maintaining rigidity, and to provide an efficient manufacturing method of the shock absorbing component and a use comprising the shock absorbing component. It is in.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on the above problems, and as a result, a shock absorbing component in which a hard material and a soft material are combined and the arrangement thereof is appropriately set, a method of manufacturing the same, and a method of manufacturing the same. It has been found that the application achieves the object of the present invention, and the present invention has been completed.

That is, the present invention is a shock absorbing component made of a hard material, wherein a soft material is arranged at least near the starting point of destruction, and both are integrated. . Further, the present invention provides at least two layers composed of a layer made of a hard material and a layer made of a soft material.
A shock-absorbing component comprising a layer, wherein a layer made of a soft material is disposed at least on the outermost layer on the side where the fracture starts. Further, the present invention is a method for manufacturing the above-described shock absorbing component, wherein one of a soft material and a hard material which has been molded in advance by an arbitrary molding method is set in a mold cavity, and heated and melted in the cavity. A method for manufacturing a shock-absorbing component, characterized by injecting the other material, cooling and solidifying the material, and integrating the two materials. The present invention also relates to the above-mentioned method for producing a shock-absorbing component, wherein an injection molding machine having at least two cylinders is used to form a soft material and a hard material arranged in each cylinder into a single cavity. A method for producing a shock-absorbing component, characterized by injecting the mixture into a mold having the following characteristics, cooling and solidifying the mixture, and integrating them. Further, the present invention is an automobile part comprising the above-mentioned shock absorbing part. Hereinafter, the present invention will be described in detail.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A plastic shock absorbing component used in an automobile or the like is subjected to an impact test close to a practical state specified in a standard, and it is confirmed whether the required performance is satisfied. In this standard test, since an impact load is applied to a predetermined position of a component by a predetermined method, it is possible to predict the starting point of the destruction from which part of the component to break. As a method of this prediction, for example, there is a simulation based on a numerical analysis of a computer in addition to an improvement based on an actual evaluation result and an empirical prediction.

[0010] On the other hand, it is known that cracks occur first in the destruction of plastic, and the cracks trigger the instantaneous destruction.

According to the present invention, the shock absorbing component is not broken by arranging a soft material that is unlikely to cause cracks near the starting point of destruction, and the required performance expected by the rigid material bearing the rigidity of the shock absorbing component is achieved. It is possible to obtain a shock absorbing component. That is, the present invention provides a shock-absorbing component having required performance without using a high-performance material by providing a soft material for the shock resistance of the shock-absorbing component and a hard material for providing the rigidity of the shock-absorbing component. be able to.

The present invention relates to a shock absorbing component made of a hard material, wherein a soft material is arranged at least near the starting point of destruction.
The shock absorbing component is characterized in that both are integrated. FIG. 1 is a drawing showing an example of the shock absorbing component of the present invention, in which a soft material is partially disposed. When an impact load 4 is applied in a state where the end portion of the shock absorbing component made of the hard material 1 as shown in FIG. 1A is supported by the fixed portion 3, the side opposite to the impact surface as shown in FIG. It is the starting point 6 of destruction. The soft material 2 that is unlikely to cause cracks is arranged in this portion, and the hard material and the soft material are integrated, so that the shock absorbing performance of the shock absorbing component is improved.

[0013] The present invention also provides a shock absorbing component comprising at least two layers composed of a layer made of a hard material and a layer made of a soft material, wherein at least the outermost layer on the side where fracture starts is made of a soft material. The shock absorbing component is characterized in that a layer comprising: FIG. 2 is a drawing showing an example of the above-described shock absorbing component of the present invention, which is formed of a two-layer laminate. As shown in FIG. 2A, when an impact load 4 is applied in a state where the end of the shock absorbing component composed of the layer made of the hard material 1 and the layer made of the soft material 2 is supported by the fixed portion 3, As shown in FIG. 2B, a tensile force 5 acts on the side opposite to the impact surface, and this portion serves as a starting point 6 of destruction. By arranging a layer made of the soft material 2 in which cracks are unlikely to occur in this portion, that is, the outermost layer, the impact resistance of the shock absorbing component is improved. FIG. 3 is a drawing showing an example of the above-described shock absorbing component of the present invention, which is formed of a three-layer laminate. It has a three-layer structure of a layer made of the soft material 2 / a layer made of the hard material 1 / a layer made of the soft material 2. Even with such a shock-absorbing component, the impact resistance is improved as described above.

The flexural modulus of the soft material in the shock absorbing component of the present invention is preferably 80% or less, more preferably 50% or less, as compared with the flexural modulus of the hard material. The bending elastic modulus of the hard material is usually 700 to 20,000 MPa.

[0015] The soft material and the hard material used in the present invention are both made of a thermoplastic resin, so that the molten resin can be fused, which is preferable in the production method. Examples of the thermoplastic resin include polyethylene, polypropylene, thermoplastic elastomer, polyvinyl chloride, nylon, polycarbonate, polyethylene terephthalate, PMMA, A
Various thermoplastic resins such as a BS resin, a modified product thereof, a polymer alloy, and a mixture thereof may be mentioned, and one or more of these may be used. Also,
Such thermoplastic resins or thermoplastic resin compositions include, for example, various commonly used fillers such as talc, mica, glass fiber, rubber, and the like, antioxidants, ultraviolet absorbers, flame retardants, coloring agents, and the like. May be added as necessary.

As the thermoplastic resin used in the present invention, for example, a homopolymer such as ethylene or propylene or α
-An olefin resin such as a copolymer with another copolymer component such as an olefin or a resin composition mainly composed of an olefin resin is preferable in terms of recycling after use of the product. Here, as a resin composition mainly composed of an olefin resin,
An olefin-based resin may be one in which a filler such as talc, mica, glass fiber, rubber or the like is contained as necessary.

The hard material composed of an olefin resin or a resin composition mainly composed of an olefin resin is preferably a propylene resin or a resin composition mainly composed of a propylene resin for obtaining a suitable shock absorbing component. As the propylene-based resin, for example, propylene homopolymer, propylene-α-olefin random copolymer, propylene-α-
Olefin block copolymers and the like can be mentioned. As the α-olefin, ethylene, butene-1, pentene-
1, hexene-1, octene-1, etc., having 2 to 4 carbon atoms
0 α-olefin. As a resin composition mainly composed of a propylene-based resin, propylene-based resin,
For example, a filler containing a filler such as talc, mica, glass fiber, or rubber as necessary may be used.

The soft material made of an olefin resin or a resin composition mainly composed of an olefin resin is preferably made of the following propylene block copolymer to obtain a suitable shock absorbing component. Propylene-based block copolymer: a propylene-ethylene copolymer portion in which the content of a repeating unit derived from ethylene in the first step (hereinafter, referred to as “ethylene unit”) is 1.5 to 6.0% by weight ( A component) is produced in an amount of 40 to 85% by weight based on the total amount of the polymer (the sum of the component A and the following component B). Then, in the second step, the content of the ethylene unit is 7 to 17% by weight.
Is a block copolymer obtained by producing 15 to 60% by weight of the propylene-ethylene copolymer portion (B component) of the total polymer amount (total of the A component and the B component), and the limit of the B component The viscosity ([η] B) is 2 to 5 dl / g, and the ratio ([η] B / [η] A) between the intrinsic viscosity of component B ([η] B) and the intrinsic viscosity of component A ([η] A) ) Is a propylene-based block copolymer of 0.5 to 1.8 The propylene-based block copolymer used in the present invention is a propylene-ethylene copolymer part in the first step and a propylene-ethylene copolymer part in the second step. A typical block in which a propylene-ethylene copolymer portion having a different ethylene unit content is obtained by sequential polymerization with a copolymer block, in which a copolymer terminal and another copolymer terminal are connected by a bond. It means not a copolymer but a kind of a blend-type copolymer. The propylene-based block copolymer is also called an impact-resistant propylene copolymer.

The proportion of the propylene-ethylene copolymer part (component A) produced in the first step and the propylene-ethylene copolymer part (component B) produced in the second step is preferably A to 40-85% by weight. %, More preferably 45%
~ 60% by weight, B component is preferably 15 ~ 60% by weight,
More preferably, it is 40 to 55% by weight.

The propylene-ethylene copolymer portion (component A) produced in the first step preferably has an ethylene unit content of 1.5 to 6.0% by weight, more preferably 2.5 to 6.0% by weight.
４4.5% by weight.

The propylene-ethylene copolymer portion (component B) to be polymerized in the second step preferably has an ethylene unit content of 7 to 17% by weight, more preferably from the viewpoint of improving the impact resistance at low temperatures. Is 10 to 17% by weight.

The intrinsic viscosity ([η] B) of the component B of the propylene-based block copolymer used in the present invention is preferably from 2 to 5.
dl / g, and more preferably 2.5 to 4.0 dl / g. The ratio ([η] B / [η] A) of the intrinsic viscosity ([η] B) of the component B and the intrinsic viscosity ([η] A) of the component A is preferably 0.5 to 1.8, More preferably 0.8-1.
5

The propylene block copolymer used in the present invention has a molecular weight of 2 which is soluble in xylene at 20 ° C. in the total polymer.
It is preferable that the content of the component of 6000 or less is 6% by weight or less from the viewpoint of suppressing the extraction amount with n-hexane or the like.

The propylene-based block copolymer used in the present invention has a difference between the content of ethylene units of component B (EB) and the content of ethylene units of component A (EA) from the viewpoint of impact resistance at low temperatures. (EB-EA) is preferably 3 to 15% by weight, more preferably 5 to 12% by weight.

The propylene block copolymer used in the present invention is a batch polymerization method in which, for example, a component A is polymerized in the same polymerization tank using a Ziegler-Natta type catalyst, and then the component B is polymerized. Alternatively, it can be produced by a continuous polymerization method for continuously polymerizing the component A and the component B using a polymerization tank comprising at least two tanks.

Specifically, for example, (a) in the presence of an organosilicon compound having a Si—O bond, a compound represented by the general formula Ti (OR ¹ ) _n X _4-n (R ¹ has ¹ to 2 carbon atoms)
0 represents a hydrocarbon group, X represents a halogen atom, and n represents a number 0 <n ≦ 4. The trivalent titanium compound obtained by treating a solid product obtained by reducing the titanium compound and / or ether compound represented by the formula (1) with an organomagnesium compound with a mixture of an ester compound, an ether compound and titanium tetrachloride. (B) an organoaluminum compound; (c) a catalyst system comprising a silicon compound having a Si—OR ² bond (R ² is a hydrocarbon group having 1 to 20 carbon atoms); or (a) A titanium compound represented by the general formula Ti (OR ¹ ) _n X _n-4 (R ¹ is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen atom, and n is a number satisfying 0 <n ≦ 4). An organoaluminum compound represented by the general formula: AlR ² _m Y _3-m (R ² represents a hydrocarbon group having 1 to 20 carbon atoms, Y represents a halogen atom, and m represents a number of 1 ≦ m ≦ 3) Obtained by reducing A solid product containing a hydrocarbyloxy group insoluble in a hydrocarbon solvent is prepolymerized with ethylene, and then a slurry is formed at a temperature of 80 to 100 ° C in a hydrocarbon solvent in the presence of an ether compound and titanium tetrachloride. Using a hydrocarbyloxy group-containing solid catalyst component obtained by treating in a state, and a Ziegler-Natta type catalyst having at least titanium, magnesium and halogen as essential components, such as a catalyst system comprising (b) an organoaluminum compound, The molar ratio of Al atoms in component b) / Ti atoms in component (a) is from 1 to 2000, preferably from 5 to 1500;
The molar ratio of Al atoms in component (c) / component (b) is set to 0.0
The polymerization temperature is 20 to 150 ° C, preferably 50 to 95 ° C.
C., the polymerization pressure is from atmospheric pressure to 40 kg / cm ² G, preferably from ^{2 to} 40 kg / cm ² G, in the first step in the absence of an inert solvent substantially in the absence of an inert solvent. To produce a propylene-ethylene copolymer portion (component A), and then supply propylene, ethylene and hydrogen in the gas phase in the second step to supply the propylene-ethylene copolymer portion ( (B component).

The propylene-based block copolymer can change the fluidity represented by, for example, a melt flow rate by a known method in the presence or absence of an organic peroxide at the time of melt-kneading. For example, adding a peroxide such as 2,5-dimethyl-2,5-ditert-butylperoxyhexane, mixing with a Henschel mixer, melt-kneading at 250 ° C., and adjusting the melt flow rate. The propylene-based block copolymer may further contain an antioxidant, an ultraviolet absorber, an antistatic agent, an antifogging agent, a nucleating agent, and the like, if necessary.

The soft material composed of an olefin resin or a resin composition mainly composed of an olefin resin used in the present invention may be a thermoplastic elastomer composed of an ethylene / α-olefin copolymer rubber and an olefin resin, or ethylene. What consists of a partially crosslinked thermoplastic elastomer obtained by dynamically crosslinking a mixture of an α-olefin copolymer rubber and an olefin resin in the presence of a crosslinking agent is preferable for obtaining a more suitable shock absorbing component. .

Examples of the ethylene / α-olefin copolymer rubber include rubbers containing olefin as a main component, such as ethylene / propylene copolymer rubber and ethylene / propylene / non-conjugated diene copolymer rubber. Examples of the non-conjugated diene include dicyclopentadiene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene, and methylene norbornene. Among such ethylene / α-olefin copolymer rubbers, ethylene / propylene / ethylidene norbornene rubber (hereinafter referred to as EPDM) is preferable.

The olefin resin includes, for example, polypropylene, propylene-ethylene copolymer,
A copolymer of propylene and an α-olefin other than propylene is preferably used.

In the above thermoplastic elastomer, the ratio of the ethylene / α-olefin copolymer rubber to the olefin resin is usually from 5:95 to 80:20 by weight.

In producing a partially crosslinked thermoplastic elastomer, an organic peroxide is usually used as a crosslinking agent. As the organic peroxide, for example, dialkyl peroxide is preferable. Further, in the presence of a crosslinking aid such as a bismaleimide compound, it is preferable to perform dynamic crosslinking using a very small amount of an organic peroxide, and in this case, the ethylene / α-olefin-based copolymer rubber is appropriately Crosslinking improves heat resistance and at the same time provides high fluidity.

The crosslinking aid is used in an amount of not more than 1.5 parts by weight, preferably not more than 0.6 parts by weight, based on 100 parts by weight of the total of the ethylene / α-olefin copolymer rubber and the olefin resin. , The organic peroxide is 0.2 parts by weight or less,
Preferably 0.1 parts by weight or less, more preferably 0.07 parts by weight
Used in parts by weight or less. For dynamic crosslinking, a method by continuous kneading and extrusion such as single-screw kneading and extrusion or twin-screw kneading and extrusion is suitable.

According to the shock absorbing component of the present invention, one of a soft material and a hard material previously formed by an arbitrary forming method is set in a mold cavity, and the other material heated and melted is injected into the cavity. It can be manufactured by cooling, solidifying, and integrating both.

The method of integrating the hard material and the soft material in the above-mentioned manufacturing method varies depending on the shape, size, required physical properties and the like of the final product, but specific examples include the following methods. (1) Insert a soft material preformed by any one of injection molding, extrusion molding, calendering molding, compression molding, etc. into a mold of an injection molding machine, and inject a hard material into the remaining portion to form a soft material. And heat fusion. (2) Insert a hard material preformed by any one of injection molding, extrusion molding, calendering molding, compression molding, etc. into a mold of an injection molding machine, and inject a soft material into the remaining part to form a hard material. And heat fusion. (3) A method in which a soft material is first injected and solidified by cooling using a multicolor injection molding machine and a multicolor molding die, and then a hard material is injected to be thermally fused with the soft material. (4) A method in which a hard material is first injected and cooled and solidified by using a multicolor injection molding machine and a multicolor molding die, and then a soft material is injected to be thermally fused with the hard material.

Further, the shock absorbing component of the present invention can be obtained by using an injection molding machine having at least two cylinders to convert a soft material and a hard material arranged in each cylinder into a mold having a single cavity. It can be manufactured by injecting, cooling and solidifying, and integrating both.

The method of integrating the hard material and the soft material in the above-mentioned manufacturing method varies depending on the shape, size, required physical properties and the like of the final product, but specific examples include the following methods. (1) A soft material layer / a soft material layer / a soft material layer is formed by first injecting a soft material, then injecting a hard material and cooling and solidifying it by a sandwich molding method using two types of molten resins. A method of obtaining a three-layer laminate composed of layers in the order of:

Further, the shock absorbing component of the present invention may be a rib structure as shown in FIG. 4. In this case, when an impact load 4 is applied, the vicinity of the intersection 41 of the rib becomes a starting point of destruction. By arranging the soft material 2 near the intersection 41 of the ribs, the impact resistance is improved. FIG. 4 is an example of an embodiment of the present invention, and is a drawing in which a soft material is arranged near an intersection of a rib of a rib structure.

The impact-absorbing component of the present invention can be used in various applications, for example, an instrument panel for protecting an occupant's head, a pillar garnish, a roof rail garnish, a door grab outer for protecting an occupant's knee,
It is suitable for a column cover, a door trim for protecting an occupant in the event of a collision from the side, a bumper fascia for protecting a vehicle body in the event of a collision, a vehicle interior / exterior component such as a bumper beam, and a home appliance / light electric product housing. In particular, the shock-absorbing component of the present invention is very suitable to be used for a bumper beam among other automotive components. Specifically, as shown in FIG. 5, it is preferable to dispose the soft material 2 in the vicinity of the vehicle body, which is the starting point of the destruction on the side 51 opposite to the impact load 4 on the bumper beam made of the hard material 1. FIG. 5 is a view showing an example of the embodiment of the present invention in which a soft material is disposed on a bumper beam. Reference numeral 3 denotes a fixing portion for fixing the bumper beam to a vehicle body.

[0040]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

In these examples and comparative examples, the test methods used for various evaluations are as follows. (1) Compression molding conditions Molding machine: NF-37 manufactured by Shindo Metal Industry Co., Ltd. Molded product size: 300 mm × 260 mm × 1.0 mm Heating temperature: 200 ° C., preheating time: 5 minutes, pressing force: 100
kg / cm ² , pressurization time: 5 minutes (2) Injection molding conditions Molding machine: FS160S25ASE manufactured by Nissei Plastic Industry Co., Ltd.
N Molded product size: 100 mm × 400 mm × 5 mm Cylinder temperature: 220 ° C., mold temperature: 40 ° C. (3) Melt flow rate (MFR) The melt flow rate (MFR) was measured according to the method specified in JIS-K7210 condition 14.

(4) A of propylene-based block copolymer
Ratio of Component and Component B (% by Weight) From the material balance at the time of polymerization of Component A and Component B, the ratio of Component A (PA) and the ratio of Component B (PB) were determined. (5) Intrinsic Viscosity ([η]) of Propylene Block Copolymer The measurement was carried out in tetralin at 135 ° C. using an Ubbelohde viscometer. Intrinsic viscosity of component A and component B ([η] A,
[Η] B) the intrinsic viscosity [η] A measured after the completion of the polymerization of the component A in the first step, the intrinsic viscosity [η] AB measured after the completion of the polymerization in the second step, and the ratio of the component A (PA); From the ratio (PB) of the component B, the intrinsic viscosity [η] B of the component B is calculated by the following equation.
Was decided. [Η] B = ([η] AB− [η] A × PA / 100) ×
100 / PB (6) Ethylene unit content Polymer Handbook (1995, published by Kinokuniya Bookstore)
¹³ C-N by the method described on page 616 of
The measurement was performed by the MR method. Content of ethylene unit of component A and component B (EA, EA) The content of ethylene unit (EA) measured after completion of polymerization of component A in the first step, and the content of ethylene unit measured after completion of polymerization of second step From the content (EAB), the ratio of the component A (PA), and the ratio of the component B (PB), the content (EB) of the ethylene unit of the component B was determined by the following equation. EB = (EAB-EA × PA / 100) × 100 / PB

(7) Flexural modulus Measured according to the method specified in JIS-K-7203. (8) Impact performance Each structure is cut into a size of 100 mm x 100 mm,
After leaving it in a constant temperature bath at 23 ° C. for 5 hours, it was fixed to a holder (opening diameter: 50 mmφ) installed in the constant temperature bath, and a high-rate impact tester RIT-80 manufactured by Rheometrics, Inc.
Using 00, the sample was punched at a constant speed of 1 m / sec with a dart having a tip diameter of 5/8 inch. At this time, the relationship between the load measured by the load cell installed on the dart and the dart displacement and the fracture mode were determined from the fracture surface of the sample. Materials with good impact resistance show ductile fracture, while materials with poor impact resistance show brittle fracture. Materials that show ductile fracture in this evaluation method are suitable as materials for bumper beams.

Example 1 Propylene block copolymer (Exelen KS37G1, manufactured by Sumitomo Chemical Co., Ltd., MFR = 2.5 g / 10 minutes,
Using a flexural modulus at 23 ° C. = 330 MPa), a soft material sheet of 300 mm × 260 mm × 1 mm was produced by compression molding. The polymerization ratio of the ethylene-propylene copolymer (component A) obtained in the first step of the propylene block copolymer and the ethylene-propylene copolymer (component B) obtained in the second step is 51.6 / 48. 4 and A
The content of the ethylene unit of the component and the component B is 3.6, respectively.
%, 15.2% by weight, and thus the difference in the content of ethylene units (EB-EA) was 11.6% by weight. The intrinsic viscosity of the powder constituting the copolymer is 3.03 dl / g for the component A ([η] A) and 3.96 dl / g for the component B ([η] B). ([Η] B / [η]
A) is 1.31. The propylene block copolymer (KS37G1) is a pellet obtained by subjecting this powder to peroxide decomposition in a nitrogen gas atmosphere. This soft material sheet was cut into a size of 100 mm × 260 mm × 1 mm, the mold was closed by being in close contact with the wall surface of a mold cavity, and a resin (hard material) for injection molding was supplied into the mold to prepare a 100 mm × 4 mm.
A laminated structure of 00 mm × 5 mm was obtained. The injection molding resin is a propylene homopolymer (manufactured by Sumitomo Chemical Co., Ltd.
Sumitomo Noblen H501, MFR = 3g / 10min, 2
Flexural modulus at 3 ° C. = 1370 MPa) was used.
The obtained laminated structure was evaluated for punching impact performance by dirt from the hard material side. The starting point of the destruction was the most strained part on the back side where the dart was hit. Because the soft material was located at this site, the laminated structure exhibited ductile fracture. Table 1 shows the results.

Example 2 Thermoplastic elastomer (Sumitomo TP manufactured by Sumitomo Chemical Co., Ltd.)
E 903, MFR = 5 g / 10 min, flexural modulus at 23 ° C. is 550 MPa), and is 300 m by compression molding.
A soft material sheet of mx 260 mm x 1 mm was produced. This soft material sheet was cut into a size of 100 mm × 260 mm × 1 mm, and the mold was closed by closely adhering to the mold cavity wall surface. The same resin for injection molding (H501) as used in Example 1 was used.
Was supplied into a mold to obtain a laminated structure of 100 mm × 400 mm × 5 mm. The obtained laminated structure was evaluated for punching impact performance by dirt from the hard material side. The starting point of the destruction was the most strained part on the back side where the dart was hit.
Because the soft material was located at this site, the laminated structure exhibited ductile fracture. Table 1 shows the results.

Comparative Example 1 The same injection molding resin (H501) as used in Example 1 was used except that the soft material sheet was not bonded in the mold, and only the injection molding was performed in the same manner as in Example 1 to obtain a structure. Obtained. The obtained structure was punched out with a dirt to evaluate the impact performance. The starting point of the destruction was the most strained part on the back side where the dart was hit. The structure exhibited brittle fracture because no soft material was placed at this location. Table 1 shows the results.

COMPARATIVE EXAMPLE 2 The same laminated structure produced in Example 1 was evaluated for its punching impact performance by dirt from the soft material side opposite to that of Example 1. The starting point of the destruction was the most strained part on the back side where the dart was hit. Although a soft material was present in this laminated structure, the soft material was not disposed at this portion, so that brittle fracture was exhibited. Table 1 shows the results.

[0048]

Table 1------------------------------------------------------------------------------------------------------------------------- 2 --------------------------------------------------------- Structure thickness (mm) 55 55 Hard material H501 H501 H501 H501 Hard material thickness (mm) 4 4 5 4 Soft material KS37G1 TPE903-KS37G1 Soft material thickness (mm) 1 1-1 Impact direction Hard material side Hard material side-Soft material side Origin of fracture Soft material Soft material Hard material Hard Material Structural impact performance Ductile fracture Ductile fracture Brittle fracture Brittle fracture −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

[0049]

As described in detail above, according to the present invention,
By arranging a soft material in the vicinity of the fracture starting point, it is possible to provide a lightweight shock absorbing component having excellent impact resistance while maintaining rigidity. Further, the present invention can provide a method for easily and efficiently producing a shock absorbing component having the above excellent physical properties. Further, the present invention is suitable as an interior or exterior part of an automobile, and particularly suitable as a bumper beam.

[Brief description of the drawings]

FIG. 1 is an example of a shock absorbing component of the present invention, showing a form in which a soft material is partially disposed.

FIG. 2 is a drawing showing an example of a shock absorbing component of the present invention, which comprises a two-layer laminate.

FIG. 3 is a drawing showing an example of a shock absorbing component of the present invention, which comprises a three-layer laminate.

FIG. 4 is an example of the shock absorbing component of the present invention, showing a form in which a soft material is arranged near an intersection of a rib of a rib structure.

FIG. 5 is a view showing a form in which a soft material is arranged in a bumper beam which is an application example of the present invention.

[Explanation of symbols]

1 ... hard material, 2 ... soft material, 3 ... fixed part, 4
... Impact load 5 ... Tensile force, 6 ... Start point of destruction, 41 ... Rib intersection 51 ... Surface opposite to impact load

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J066 AA02 BA04 BB01 BB04 BD05 BE06 4J002 BB11W BB12W BB15X BP02X GF00 GN00 4J026 HA03 HA04 HA27 HB03 HB04 HB50

Claims (12)

[Claims] 1. A shock-absorbing component comprising a hard material, wherein a soft material is disposed at least near the starting point of destruction, and both are integrated. 2. A shock-absorbing component comprising at least two layers composed of a layer made of a hard material and a layer made of a soft material, wherein at least the outermost layer on the side where fracture starts is provided with a layer made of a soft material. A shock-absorbing component characterized by being arranged. 3. The shock absorbing component according to claim 1, wherein both the soft material and the hard material are made of a thermoplastic resin. 4. The shock absorbing component according to claim 3, wherein the thermoplastic resin is an olefin resin or a resin composition mainly composed of an olefin resin. 5. The shock absorbing component according to claim 4, wherein the hard material composed of an olefin resin or a resin composition mainly composed of an olefin resin is composed of a propylene resin or a resin composition mainly composed of a propylene resin. 6. A shock-absorbing component according to claim 4, wherein the soft material comprising an olefin-based resin or a resin composition mainly comprising an olefin-based resin comprises the following propylene-based block copolymer. Propylene block copolymer: The propylene-ethylene copolymer portion (component A) having a content of a repeating unit derived from ethylene in the first step of 1.5 to 6.0% by weight is converted into a total polymer amount (A 40-85)
% Of the propylene-ethylene copolymer portion (component B) having a content of the repeating unit derived from ethylene of 7 to 17% by weight in the second step. A block copolymer obtained by producing 15 to 60% by weight of the total (B), the intrinsic viscosity of component B ([η] B) is 2 to 5 dl / g, and the intrinsic viscosity of component B ([η] B ) And the intrinsic viscosity ([η] A) of the component A ([η] B / [η] A) is a propylene-based block copolymer having a ratio of 0.5 to 1.8. 7. The propylene-based block copolymer has a content of a repeating unit (E) derived from ethylene as the component B.
The difference (EB-EA) between B) and the content (EA) of the repeating unit derived from ethylene of the component A is 3 to 15% by weight.
7. The shock absorbing component according to claim 6, wherein 8. A soft material comprising an olefin resin or a resin composition mainly composed of an olefin resin is ethylene.α.
-A portion obtained by dynamically cross-linking a thermoplastic elastomer comprising an olefin-based copolymer rubber and an olefin-based resin, or a mixture of an ethylene / α-olefin-based copolymer rubber and an olefin-based resin in the presence of a cross-linking agent; 5. The shock absorbing component according to claim 4, comprising a crosslinked thermoplastic elastomer. 9. A method for manufacturing a shock-absorbing component according to claim 1, wherein one of a soft material and a hard material preliminarily molded by an arbitrary molding method is set in a mold cavity. Then, the other material heated and melted is injected into the cavity, cooled and solidified, and the two are integrated, thereby producing a shock absorbing component. 10. The method for producing a shock absorbing component according to claim 1, wherein the soft material is arranged in each cylinder by using an injection molding machine having at least two cylinders. And a method of injecting a hard material into a mold having a single cavity, solidifying it by cooling, and integrating them. 11. An automobile part comprising the shock absorbing part according to claim 1. 12. The automobile part according to claim 11, wherein the automobile part is a bumper beam.