JPH03231690A - Hollow impact damping material and hitting tool consisting of the same - Google Patents

Abstract

PURPOSE:To restrain impact vibration produced by the collision and hitting operations between objects bh providing a laminated body comprising reinforced resin layer and a vibration restraining material layer having a specified vibrational loss factor with the outermost layer composed of the fiber reinforced resin layer. CONSTITUTION:A hollow impact damping material 1 constituting a portion of an aggregate of a racket or golf club (hitting tool) is composed of a laminate having a fibre reinforced resin layer 2 and at least one layer of vibration restrain material layer 3 having at least 0.01 of vibrational loss factor in room temperature and provided on the outermost layer with the fiber reinforced resin layer 2. The resin constituting the fiber reinforced resin layer is selected from epoxy resin, unsaturated polyester resin or the like of thermosetting resin. For the vibration restraining material is preferably used a resin setting material consisting of a resin composition containing mainly an epoxy resin having fluidity from room temperature to 100 deg.C, a polyamide resin and at least one kind of inorganic filler selected from graphite, ferrite and mica.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a shock absorbing material that can significantly suppress impact vibrations generated by collisions between objects, impact operations, and the like.

(Prior art) Various types of metal pipes and fiber-reinforced plastic pipes have been manufactured in the past, but these have only been studied with a focus on improving strength characteristics and weight reduction. , none have considered the issue of shock vibration.

In general, impact vibrations occur when objects collide,
There is currently no concrete solution to the technology for controlling such special vibrations.

(Problems to be Solved by the Invention) The most problematic field due to the generation of impact vibrations is typically the field of hitting tools (equipment, tool, equipment) that performs desired work or play by performing a hitting operation. When a hitting operation is performed using such a hitting tool, the grip portion of the hitting tool is subjected to strong impact vibrations.

If such impact vibrations are continued for a long period of time, a numbing sensation will remain in the wrists, arms, elbows, etc., and as the discomfort and fatigue caused by such numbing sensation accumulates, it will eventually cause damage to the human body.

The present invention is the result of careful consideration of the problems caused by the above-mentioned collisions and impacts.

That is, an object of the present invention is to provide a hollow material that can significantly suppress impact vibrations caused by collisions between objects, impact operations, and the like.

Further, according to the present invention, for example, it is possible to solve the accumulation of discomfort and fatigue caused by shock vibrations in the wrists, arms, and elbows that remain in the wrists, arms, and elbows, and to eliminate concerns about disorders such as elbow pain. It is possible to perform the striking operation continuously for a long period of time comfortably.

(Means for Solving the Problems) The present invention employs the following means to achieve the above-mentioned objects.

That is, the hollow impact cushioning material of the present invention has a fiber reinforced resin layer and a vibration loss coefficient of 0.01 or more at room temperature.
It is characterized in that it is composed of a laminate including at least one vibration suppressing material layer, and the outermost layer of the laminate is composed of the fiber-reinforced resin layer.

Further, the hitting tool of the present invention includes at least a part of the aggregate constituting the hitting tool including a fiber reinforced resin layer and at least one vibration suppressing material layer having a vibration loss coefficient of 0.01 or more at room temperature. It is characterized by being composed of a hollow shock-absorbing material made of.

(Function) The present invention solves the problem of impact vibrations that occur due to collisions between objects or impact operations, but the fields where problems occur due to such impact vibrations include work that involves impact operations, It's a play.

That is, a typical example is one that uses a hitting tool (instrument, tool, instrument), and the present invention will be described below using this hitting tool as a representative example.

Examples of such hitting tools include tools, martial arts equipment, self-defense equipment, and general sports equipment.

Examples of tools include hammers, mallets, axes, etc.; examples of martial arts tools include nunchakus, wooden swords, sticks, etc.; examples of self-defense tools include batons, etc. Examples of general sports equipment include rackets for tennis, tennis, badminton, and squash, sticks for hockey, ice hockey, cricket, and gateball, golf clubs, and hitting tools such as baseball bats.

Among these hitting tools, tennis and golf are currently the most popular, and many people complain of elbow pain. The hollow impact cushioning material of the present invention is preferably used as an aggregate for such sports rackets and clubs.

The present invention surprisingly suppresses impact vibrations during hitting to a significantly low level when a composite hollow material consisting of a vibration suppressing material and a fiber-reinforced resin containing the same is used as an aggregate constituting the hitting tool. It was completed by investigating the fact that it is possible.

As the above-mentioned fiber-reinforced resin, a material having sufficient strength and rigidity as the aggregate of a hitting tool, such as a thermoplastic resin or a thermosetting resin, can be used, but preferably a thermosetting resin has high rigidity. It's fine.

Thermoplastic resins include polyamide resins, polyester resins, polycarbonate resins, ABS resins, polyvinyl chloride resins, polyacetal resins, polyacrylate resins, polystyrene resins, polyethylene resins, and polyvinyl acetate resins. , polyimide resins, and mixed resins thereof can be used.

As the thermosetting resin, epoxy resin, unsaturated polyester resin, phenol resin, urea resin, melamine resin, diallyl phthalate resin, urethane resin, polyimide resin, etc., and mixed resins thereof can be used. .

These fiber-reinforced resins are preferably reinforced with reinforcing fibers such as inorganic fibers such as metal fibers, carbon fibers, and glass fibers, aramid fibers, and other high-strength synthetic fibers.

These reinforcing fibers may be used alone or as a mixture thereof for reinforcement, and may be used in the form of long fibers, short fibers, or a mixture thereof.

The vibration suppressing material in the present invention is composed of a substance having a vibration loss coefficient of 0.01 or more at room temperature, which will be described later.
It plays a major role in damping impact vibrations.

Materials that make up such substances include metals themselves with high specific gravity such as lead and copper, elastic rubber, synthetic resins, etc.
Mixtures of these resins with metals, ceramics, and inorganic fillers such as graphite, ferrite, and mica can be used.

As such a metal, for example, metal particles or metal fibers made of lead, iron, copper, etc. can be used.

Further, as the elastic rubber, natural rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber, etc. can be used.

Further, as the synthetic resin, polyester resin, polyamide resin, polyvinyl chloride resin, polyvinyl acetate resin, epoxy resin, etc. can be used.

Among these vibration suppressing materials, materials with vibration damping properties made of elastic rubber and synthetic resin can be processed into various desired shapes, such as protrusions, plates, and films, and can also be laminated. It is preferable because it can be easily combined. Moreover, among the above-mentioned materials, those made of resin compositions made of epoxy resins, polyamide resins, and inorganic fillers have excellent impact vibration suppression properties. In particular, at least one selected from epoxy resins that have fluidity between room temperature and 100°C, polyamide resins that have fluidity between room temperature and 100°C, and graphite, ferrite, and mica.
A cured resin product consisting of a resin composition containing an inorganic filler as a main component is preferably used.

That is, the epoxy resin having fluidity at room temperature to 100°C is preferably a resin having at least two or more glycidyl ether groups, and more preferably has a viscosity of 1 to 300 voids at 25°C and an epoxy equivalent. 100 to 500, preferably those with a molecular weight of 200 to 1,000. Specifically, for example, Epicote 828.827.
834.807 (manufactured by Yuka Shell Chemical Co., Ltd.), etc. can be used.

In addition, as a polyamide resin having fluidity at room temperature to 100°C, preferably the viscosity at 25°C is 3 to 2000.
Those having a void and amine value of 100 to 800 are suitable because they act effectively as a curing agent for epoxy resins and as a flexibility imparting agent for the resin after curing. Specifically, for example, Tomide #225-X, #215-X, #225
(manufactured by Fuji Kasei Co., Ltd.), Persamide 930.11
5 (manufactured by General Mills), Epon-V15
(manufactured by Shell), etc. can be used.

Such polyamide resin acts as a curing agent for epoxy resin, but in order to shorten the curing time and sufficiently progress the curing of the molded product, a commonly used curing agent for epoxy resin can be used in combination. . Such curing agents include aliphatic amines such as triethyltetramine, propatoolamine, aminoethylethanolamine, P-phenylenediamine, and tris(dimethylamino).
Aromatic amines such as methylphenol and benzylmethylamine, and carboxylic acids such as phthalic anhydride and maleic anhydride can be used. The amount of the curing agent to be added may be sufficient for curing, taking into consideration the epoxy equivalent, amine equivalent, and acid equivalent.

The inorganic filler filled in these resins is preferably at least one selected from graphite, ferrite, and mica. Among such inorganic fillers, graphite is preferably used because it has excellent impact vibration suppressing properties, and among these, those having an aspect ratio of 3 to 70 are preferable. The aspect ratio is a value obtained by dividing the diameter of a graphite particle by its thickness, and those in the above range may have excellent wettability and mixing characteristics with respect to resin.

The above components are preferably blended in the following proportions.

That is, the blending amount of polyamide resin with respect to 100 parts of epoxy resin is 100 to 800 parts, more preferably 2 parts.
00 to 500 parts, and the inorganic filler is 30 to 120 parts, more preferably 40 to 100 parts, based on 100 parts of the total amount of these resins (including monoglycidyl ether, which will be described later). .

Furthermore, by further blending a monoglycidyl ether compound with the above-mentioned resin composition, it is possible to provide a vibration-damping resin material that is extremely flexible and has excellent workability, and also has an excellent impact vibration damping effect. This is preferable because it allows Particularly preferred are monoglycidyl ether compounds having an epoxy equivalent of 80 to 400 and a molecular weight of 80 to 400. Specifically, octadecyl glycidyl ether, phenyl glycidyl ether, butylphenyl glycidyl ether, etc. can be preferably used.

The compounding amount of this compound is preferably 5 to 45 parts, more preferably 10 to 25 parts, per 100 parts of the epoxy resin.

A more preferable material as the vibration suppressing material in the present invention is one having a vibration loss coefficient of 0.02 or more, particularly preferably 0.04 or more in the frequency range of 50 Hz to 5 kHz at room temperature of 20°C.

The above-mentioned vibration loss coefficient is measured as follows.

That is, a sample resin with a thickness of 10+n+n was pasted on a 5mm thick steel plate using a two-component poxy adhesive, and after being left for 24 hours, it was placed at room temperature (20°C) according to MIL-P22581B of the U.S. military regulations. Measure the vibration damping waveform below and find the vibration loss coefficient (η) using the following formula.

a, Decay rate (DECAY RATE)D tl(d
B/sec) (F/N) 20 log (A1/A2
) b, effective attenuation factor (EFFECTIVE DECA
Y RATE) D e, (+IB/5ec) = D
o-, DeC1 critical attenuation rate (PERCENT CR
ITICAL DAMPING)C/Cc(%)=
(183xDe)/F where, F: Natural frequency of the sample bonding plate N: Number of calculated periods A, : Maximum amplitude A in N, , : Minimum amplitude Do in N: Damping of sample bonding plate Rate DB = damping rate d of original steel plate, vibration loss coefficient (η) η = (C/Cc) / 50 As the vibration suppressing material of the present invention, the compression hardness at 25% compression specified by JIS K6767 is 5. 0kg/car
Below, preferably 3.0kg/c! [A material in which the following materials are mixed or combined to form an island component or layer can also be used.

Here, the compression hardness is measured in a temperature-controlled room at 20° C. using a compression hardness tester (manufactured by Kiki Daiei Kagaku Seiki Seisakusho).

The test piece is 50 mm long, 50 mrn wide, and about 25 mm thick.
Use a rectangular parallelepiped.

The thickness of the central part of the test piece was measured, and then the test piece was placed in a predetermined position in the testing machine, and the compression speed was 10 mm/min.
, the compressed material is compressed to 25% of the initial thickness, then stopped, and after being left in that state for 20 seconds, the load is measured, the stress is calculated using the following formula, and the stress value is determined as the compression hardness (H). Note that, depending on the case, the compressive hardness (stress value) may be determined using smaller dimensions (length, width) of the test piece.

H= P -1 where P: Load after 20 seconds under 25% compression (kg
) W: Width of test piece (cm) l: Length (cm) As such a cushioning material, the following can be used, but it is not limited to these.

Inorganic elastomers: Rubber-like sulfur, silicon fluoride polymers, phosphorus-based, silicon-based (siloxane-based polymers,) phosphazene-based elastomers (phosphorous and nitrogen skeletons), etc.

Polymer gel type: polyvinyl alcohol hydrogel, sodium acrylate/acrylamide copolymer gel, etc.

Organic elastomer m: Polyvinyl chloride, polyurethane, polyamide, polystyrene, ethylene vinyl acetate copolymer, ethylene ethyl acrylate, polyolefin, polyester, epoxy resin, etc.

Rubber elastomer m: Natural rubber, styrene-butadiene rubber, nitrile rubber, isoprene rubber, hydrin rubber, chloroprene rubber, etc.

Foamed plastics: Polyurethane-based, polystyrene-based, polyethylene-based, fluorine-based, EVA-based, phenol-based, PvC-based, polyurea-based resins, etc.

Next, the hollow impact cushioning material of the present invention is formed, for example, by laminating a fiber reinforced resin layer on a sheet made of a vibration suppressing material. The fiber-reinforced resin generally used is a prepreg prepared by impregnating or coating reinforcing fibers with a resin. This prepreg exhibits a stronger reinforcing effect in the direction of orientation (arrangement) of the reinforcing fibers, so
By varying the fiber arrangement angle of each prepreg during lamination, a good balance of reinforcing effects can be achieved.

Such prepreg is the main component of the aggregate of hollow impact cushioning materials, and for example, after wrapping several plies of the prepreg around a core rod (hollow or solid metal rod, resin rod),
The vibration suppressing material sheet is wrapped, and then several plies of prepreg are wrapped. Note that any number of vibration suppressing material layers can be arranged at an appropriate position other than the outermost layer in the thickness of the final product. An example of such a molding method is given below.

One molding method is to directly heat and mold the rod-shaped product with a core rod obtained as described above.

In addition, as another molding method, the above-mentioned core rod may be used as it is as the core of the hollow impact cushioning material. In this case, the core material is made of the material to be put into practical use, and the core material is wound as described above to create a body, which is then fitted into a mold and heated to be formed. For example, after wrapping a synthetic resin tube such as nylon as a core material in the order of prepreg, vibration suppressing material, and prepreg as described above, it is placed in a mold, and compressed air is injected into the core material tube at the same time as heating. , the tube is molded along a mold.

Instead of such a core material, a synthetic resin that foams when heated can also be used as the core material. In this case, after the resin is loaded onto the body, the resin is wrapped around the prepreg and the vibration suppressing material, and then the resin is molded as it is or by being placed in a mold and heated and foamed.

The hollow impact cushioning material of the present invention is limited to an annular structure made of fiber-reinforced resin material. In other words, such hollow materials tend to amplify impact vibrations compared to solid materials, but by combining a specific vibration suppressing material, the impact vibrations can be effectively offset. .

Although typical structural examples thereof are shown in FIGS. 1 to 4, the hollow impact cushioning material of the present invention is not limited to these structures.

The hollow shock absorbing material 1 shown in FIG. 1 is an example in which a vibration suppressing material layer 3 is arranged around the entire circumference of an aggregate middle layer composed of a fiber-reinforced resin layer 2. FIG. 2 shows a modification of the structure shown in FIG. 1, in which the vibration suppressing material layer 3 is disposed around half the circumference. FIG. 3 is an example of a structure in which intermittent portions are partially provided in the structure of FIG. 1. FIG. 4 shows an example of a structure in which vibration suppressing material layers 3 are arranged in multiple layers.

Further, the hollow shock absorbing material of the present invention may have a structure in which various combinations of the structural examples shown in FIGS. 1 to 4 described above are used, or may have a structure in which the vibration suppressing material layer is arranged in a portion of the aggregate in the axial direction.

The shape of such a hollow impact cushioning material may be any shape, in short, it is sufficient that it is annular, for example, a circle,
Various shapes can be used, such as triangular and rectangular.

The apparent vibration loss coefficient of the thus obtained hollow impact cushioning material of the present invention or a hitting tool made using the same is preferably 0.02 or more, more preferably 0.03 or more, particularly preferably 0.04 or more. It exhibits an excellent impact vibration damping effect.

The method for measuring this apparent vibration loss coefficient is as follows.

That is, a micro-acceleration pickup is attached to one end of the sample or the center of the handle or grip of the batting tool and suspended, and the other end (head or zenith) of the sample or the batting tool is suspended.
is struck lightly with a hammer, and the resonant frequency with the greatest impact strength is detected. Next, a frequency filter near the detection resonance frequency is set, the sample is tapped again with a hammer, the attenuation waveform of the vibration is measured with an FFT analyzer (manufactured by Ono Side Lid Co., Ltd.), and the waveform is analyzed with a microcomputer ( MIL-P22581 manufactured by NEC Corporation
The vibration loss coefficient (η) is measured according to formula B.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1, Comparative Example 1 As a tennis racket structural material, glass fibers made of E glass and carbon fibers were used in a weight ratio of 80/20,
Using epoxy resin, a unidirectional blipreg sheet with a fiber weight ratio of 65% and a basis weight of 350 g/ni' is produced.
Two sheets were stacked in a 45° direction to form a 90° orthogonal prepreg sheet.

On the other hand, as a vibration suppressing material, the following resin composition was spread and cured to obtain a resin sheet with a thickness of 0.2 mm.

Epoxy resin 16° 3 parts (Epicote #828, Yuka Shell I) Octadecyl glycidyl ether 3.2 parts Polyamide resin 3
8.3 parts (Tomide #225-X, manufactured by Fuji Kasei ■) 1
Lis(nomethyla;do)methylphenol
2. 2 part graphite
40.0 parts The vibration loss coefficient of this resin sheet at 20'C was 0.04 in the frequency range of 50H2 to 5KH2.

This resin sheet was cut into a rectangle of 25 x 800 mm. The weight of the sheet was 5.6 g.

Continuously, the above prepreg sheet is approximately 350 x 1600
It was cut into a rectangle of mm size and wrapped around the core of a nylon film tube. At this time, the resin sheet was arranged as the second layer from the outside and in the center of the tube to produce a tubular laminate.

Next, this tubular laminate was placed in a tennis racket mold and placed in a curing oven at 130°C. When the resin softened, compressed air was forced into the nylon tube, and after hardening for 2 hours, the molded product was taken out from the mold.

This molded product had a good appearance with no blisters or voids.Furthermore, after going through processes such as deburring the molded product and polishing the surface, grips and guts were attached to make it into a tennis racket.

The weight of this racket was 355g. The apparent vibration loss coefficient of this racket was measured and found to be 0°022 at 20°C and a resonance frequency of 137.5flZ.

When using this racket, the impact vibrations transmitted to the wrists and elbows were extremely small compared to commercially available rackets and comparative examples described below, and the ball could be hit comfortably.

For a comparative example, a conventional tennis racket was obtained in the same manner as in Example 1 without laminating the vibration suppressing material sheet (Comparative Example 1).

The weight of this racket was 349g. The apparent vibration loss coefficient of this racket was measured and found to be 0°007 at 20°C and a resonance frequency of 14.2.582. When using this racket, the feeling of hitting a ball was unpleasant due to large vibrations transmitted to the wrist and elbow.

Examples 2 to 5, Comparative Example 2 A vibration suppressing material made of the following resin composition and having a thickness of 15
A 0μ resin sheet was used.

Epoxy resin 13.6 parts (Ebiko) #828, Yukakenel@v) Octadecyl glycidyl ether 2.7 parts Polyamide resin
31.9 parts (Tomide #225-X, manufactured by Fuji Kasei ■)
Tris(methyl)methylphenol
1. 8 parts graphite
50.0 parts The above-mentioned resin composition was
Molded and cured to a size of X 20 (mm) and heated at 20°C.
As a result of the vibration loss coefficient at 50Hz to 5Kt
(It was 0.05 in the frequency range of z.

As one prepreg, a carbon fiber bundle with a total fineness of 3300D was arranged in a fabric weight of 139 g/rrf' and coated with an epoxy resin of 207 g/m, and the obtained prepreg was prepared so that the direction in which the carbon fibers were arranged was biased. A cut piece was prepared (prepreg A).

Another prepreg was prepared by arranging carbon fiber bundles with a total fineness of 3600D and having a basis weight of 150 g/rrf' and coating them with epoxy resin 244 g/rrl'. A piece cut into short pieces was prepared (prepreg B).

First, 6 plies of the above prepreg A are wrapped around a core rod made of a steel metal rod coated with a fluorine-based mold release agent, then 1 ply of the resin sheet is wrapped thereon, and 4 plies of prepreg B are wrapped on top of that to form a laminate. Made (Example 2)
.

Next, as the first ply, the resin sheet was wound around a core rod similar to that described above, and then 6 plies of the prepreg A were wound thereon, and 4 plies of the prepreg B were wound thereon to form a laminate (Example 3). ).

Next, 6 plies of the prepreg A were wound around the core rod, then 4 plies of the prepreg B were wound, and finally 1 ply of the resin sheet was wound to form a laminate (
Example 4).

Finally, the prepreg A is wrapped around the 6-ply core rod,
Next, two plies of the prepreg B were wound, one ply of the resin sheet was wound thereon, and finally two plies of the prepreg B were wound to form a laminate (Example 5).
.

For comparison, a laminate was prepared in which 6 plies of prepreg A and 4 plies of prepreg B were laminated (Comparative Example 2).

The five types of laminates mentioned above were placed in a high-temperature thermostat at 135°C.
The epoxy resin was heated for 2 hours to harden and molded, and the metal rods were pulled out from the molded products to obtain 5 golf shaft materials.

Table 1 shows the results of measuring the apparent vibration loss coefficients of these materials for golf shafts.

Note that the apparent vibration loss coefficient in this case is a value at 20° C. and a resonance frequency of 250HX.

Table 1 The materials of Examples 2 to 5, especially Example 5, showed excellent impact vibration damping effects. When golf clubs are made from these materials and used, the impact vibrations transmitted to the wrists and elbows are much smaller in all examples than in comparative example 2, and the feel of the ball is comfortable. Ta. In particular, the club made of the material of Example 5 was extremely excellent.

(Effects of the Invention) The present invention significantly controls impact vibrations generated by collisions, impact operations, etc., and extremely effectively prevents the impact vibrations from being transmitted to the hands, body, or other parts of the body other than the part that received the impact. A hollow impact cushioning material having a damping function can be provided.

The hitting tool of the present invention does not cause unpleasant vibrations or stiffness, satisfactorily reduces arm and elbow fatigue caused by impact vibration, and does not accumulate such fatigue in the wrist, arm, elbow, etc., allowing you to work or play comfortably. can do.

Furthermore, it is expected to be an extremely useful material for applications where shock vibrations are averse, such as in precision instruments.

[Brief explanation of drawings]

Figures 1 to 4 are Structure of hollow impact cushioning material of the present invention It is a sectional view showing an example. :Hollow impact cushioning material :Fiber reinforced resin : Vibration suppression material

Claims (7)

[Claims] (1) A laminate consisting of a fiber-reinforced resin layer and at least one vibration suppressing material layer having a vibration loss coefficient of 0.01 or more at room temperature, and the outermost layer of the laminate is made of the fiber-reinforced resin. A hollow impact cushioning material characterized by being composed of layers. (2) The hollow impact cushioning material according to claim (1), wherein the resin constituting the fiber-reinforced resin layer is a thermosetting resin. (3) Claim (2) wherein the thermosetting resin is a resin selected from epoxy resins and unsaturated polyester resins.
Hollow shock absorber as described. (4) The vibration suppression material has a vibration loss coefficient of 0 at room temperature.
The hollow impact cushioning material according to claim 1, wherein the hollow impact cushioning material is made of a material having a molecular weight of 0.02 or higher. (5) The hollow impact cushioning material according to claim (1), wherein the vibration suppressing material is a cured resin made of a resin composition consisting of an epoxy resin, a polyamide resin, and an inorganic filler. (6) A hollow impact cushioning material in which at least a part of the aggregate constituting the hitting tool is composed of a fiber-reinforced resin layer and at least one vibration suppressing material layer having a vibration loss coefficient of 0.01 or more at room temperature. A hitting tool characterized by being composed of. (7) The hitting tool according to claim (6), wherein the hitting tool is a racket or a golf club.