JPH10182888A - Shock-absorbing gel material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a shock-absorbing gel material reduced in the surface stickiness, having high vibration-damping performances and reinforced by imparting high modulus of elasticity in every direction. SOLUTION: This material is obtained by mixing at least one rubber with a styrene/vinylisoprene/styrene copolymer having a styrene content of 30% or below, a softener, short fibers and a cross-linking agent comprising a peroxide and cross-linking the obtained mixture. As the softener, one for a styrene/ vinylisoprene/styrene copolymer is used. 30-70wt.% styrene/vinylisoprene/styrene copolymer is used per 100 pts.wt. total of the at least one rubber and the styrene/vinylisoprene/styrene copolymer, and 5-20 pts.wt. short fibers selected among at least one type of short fiber, mixed-spun yarn or mixed-spun fiber made of a polyamides, rayons or cotton.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock-absorbing gel material, and more particularly, to the addition of at least one rubber to reduce surface tackiness to maintain high damping performance and to add short fibers. And a shock-absorbing gel material having enhanced multiaxial reinforcement.

[0002]

2. Description of the Related Art Rubber, asphalt and the like have been well known as a shock absorbing / damping material for a long time. Although many of these have been used, their shock absorbing performance, that is, the tan δ value which is a measure of the damping performance is 0.1 to 0.3, which is not necessarily large. It has been done. Among them, a polynorbornene resin containing a large amount of oil is known. This plasticizes polynorbornene by containing oil, brings the glass transition point close to room temperature, and sets the tan δ value to 1 to 2 to dramatically improve the damping performance. On the other hand, silicone gels containing silicone as a main component are promising because of their stable temperature and frequency characteristics.

[0003]

However, a shock absorbing material containing a large amount of oil in a polynorbornene resin has a peak temperature of tan δ near room temperature and therefore has a large damping performance near room temperature. Since the width of the peak is narrow, there is a drawback that the attenuation performance greatly depends on the attenuation performance with respect to temperature and frequency and is expensive. The silicone gel also has problems such as a tan δ value of 0.2 to 0.8 and a low damping performance as compared with polynorbornene, too low elastic modulus, and high cost.

A conventional shock absorber using a styrene-vinylisoprene-styrene copolymer contains a high-molecular-weight oil in order to change the temperature range in which the hardness becomes lower or the damping becomes higher. The surface became tacky, and a large amount of oil contained therein migrated to the surface over time to amplify the tackiness. As a result, not only does the dust easily adhere to the surface of the shock absorbing material, but once it adheres, it may be difficult to separate, and it may be difficult to assemble the device using the dust, and the adhesion may be reduced. There is a need for a shock-absorbing gel material. Furthermore, there is a problem that various properties such as oil resistance, weather resistance, and heat resistance are insufficient, and a shock absorbing gel material that satisfies these properties and has high damping properties is required. Further, in the case of a conventional shock absorbing gel material, when a large impact force is locally applied, the gel material may be easily deformed. The present invention is to improve such problems, to maintain high damping performance by reducing the surface tackiness,
Further, a shock-absorbing gel material reinforced by imparting a high elastic modulus in each direction is provided.

[0005]

SUMMARY OF THE INVENTION The present invention provides at least one
A styrene / vinyl isoprene / styrene copolymer having a styrene content of 30% or less, a softener, a short fiber, and a crosslinking agent composed of peroxide are added to the kind of rubber, and the obtained compound is crosslinked. As the softener, a softener for styrene / vinyl isoprene / styrene copolymer is used, and styrene / vinyl isoprene is used for at least one kind of rubber and 100 weight parts of the styrene / vinyl isoprene / styrene copolymer in total. 30-70% by weight of styrene copolymer, and polyamide, rayon,
One or more staple fibers selected from cotton or mixed spinning, and staple fibers selected from mixed spun fibers are used
20 parts by weight of the shock absorbing gel material.

The present invention also relates to a direction in which the short fibers are most oriented in the length direction of the shock absorbing gel material (X-axis direction), and a width direction (Y-axis direction) perpendicular to the X-axis direction. Then, E ′ _Y / E ′ _Y /, which is the ratio of the dynamic storage elastic moduli E ′ _X and E ′ _Y of the shock absorbing gel material in the X-axis direction and the Y-axis direction, respectively.
E _'X includes the case in the range of 0.3 to 0.5. The present invention also includes a case where a softener for rubber and a softener for styrene / vinyl isoprene / styrene copolymer are used in combination as a softener, and a case where at least one kind of rubber is a nitrile rubber.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The impact-absorbing gel material of the present invention comprises a softener and a sticky styrene / vinylisoprene / styrene copolymer having a styrene content of 30% or less surrounded by at least one kind of rubber. The styrene / vinyl isoprene / styrene copolymer incorporates a softening agent and shifts the peak temperature of tan δ to a lower temperature side, so that the tan δ max (1 to
(100 Hz) ≧ 0.4. Further, the short fiber has a ratio E ′ _Y / E ′ which is the ratio of the dynamic storage elastic moduli E ′ _X and E ′ _{Y in} the X-axis direction and the Y-axis direction, respectively.
_{Since X} is in the range of 0.3 to 0.5 and is oriented almost randomly in each direction, a high elastic modulus is maintained in each direction and a reinforcing effect is obtained.

[0008] In the shock absorbing gel material of the present invention, at least one kind of rubber is used. The rubber contains a softener and surrounds the tacky styrene-vinylisoprene-styrene copolymer to render it non-tacky. Specific examples include nitrile rubber, hydrogenated nitrile rubber, ethylene-propylene-diene rubber, chloroprene rubber, chlorosulfonated polyethylene, acrylic rubber, ethylene-propylene-diene rubber, and natural rubber.

When surrounded by nitrile rubber, oil resistance is improved, and furthermore, styrene / vinyl isoprene / styrene copolymer is surrounded by nitrile rubber, and sea (nitrile rubber) and islands (styrene / vinyl isoprene / styrene copolymer) )
To maintain the high damping performance by reducing the surface tackiness.

[0010] Surrounding with hydrogenated nitrile rubber results in a shock-absorbing gel material having improved heat resistance and weather resistance in addition to oil resistance. Furthermore, aging resistance, weather resistance, and ozone resistance can be improved by enclosing with ethylene / propylene / diene rubber, chloroprene rubber, chlorosulfonated polyethylene, etc., and heat resistance and oil resistance can be improved by enclosing with acrylic rubber. It becomes an adhesive shock absorbing gel material.

The styrene / vinyl isoprene / styrene copolymer used in the present invention comprises a triblock copolymer in which polystyrene and vinyl-polyisoprene are bonded, and the styrene content is 30% or less. .
This copolymer has a tan δ peak temperature around 35 ° C., and has a high damping performance near this temperature. However, since the high damping temperature region is narrow, the temperature and frequency dependence of the damping performance is low. Is big. If the styrene content exceeds 30%, the rigidity of the copolymer increases and it becomes difficult to obtain a low-hardness gel material.

As the styrene / vinyl isoprene / styrene copolymer, those having a hydrogenated vinyl isoprene phase can also be used. In this case, the hydrogenation rate is 80% or more.

The styrene / vinyl isoprene / styrene copolymer is added in an amount of 30 to 70 parts by weight based on 100 parts by weight of the total of at least one kind of rubber and the styrene / vinyl isoprene / styrene copolymer. , Less than 30 parts by weight, the maximum value of tan δ measured within a frequency of 1 to 100 Hz is less than 0.4, and the damping performance is low. On the other hand, if the amount exceeds 70 parts by weight, the relative amount of the styrene / vinyl isoprene / styrene copolymer in the blend increases, so that the rigidity increases and it becomes difficult to obtain a low-hardness gel material.

The short fibers used in the present invention are nylon 6, nylon 66, nylon 46 having a length of 4 mm or more.
And one or more selected from polyamide fibers, rayon, cotton, or the like, or mixed spun or mixed spun fibers, and those subjected to an adhesive treatment with an RFL solution are used. Since the short fibers have a low elastic modulus and a high elongation at break, they are easily bent or cut when kneaded with rubber. For this reason, the obtained short fiber composite material which is difficult to be oriented has a small anisotropy, and the sheet extrusion direction,
That is, the direction in which the short fibers are most oriented in the length direction (X-axis direction), the width direction perpendicular to the X-axis direction (Y-axis direction)
Where E ′ _Y / E ′ _X which is the ratio of the dynamic storage elastic moduli E ′ _X and E ′ _{Y in} the X-axis direction and the Y-axis direction is
It is in the range of 0.3 to 0.5. Thereby, the obtained shock absorbing gel material is reinforced at least in the X-axis direction and the Y-axis direction, and is not torn even if the gel material is locally subjected to a large impact force. When the length of the short fibers is less than 4 mm, the fibers are not easily oriented and the anisotropy is reduced, but the tear resistance is reduced. Among these, polyamide fibers are more excellent in adhesiveness than other fibers and have a large reinforcing effect. Conversely, fibers such as polyester and vinylon have high rigidity and do not bend or cut during kneading, so that the short fibers are oriented in the grain direction to become an anisotropic material.

As the short fibers selected from the above-mentioned mixed spun and mixed spun fibers, those obtained by combining polyester and cotton, polyester and rayon, polyester and PVC, PVC and polyamide fibers, diacetate and triacetate are used. .

The amount of the short fibers is 5 to 20 parts by weight based on 100 parts by weight of the total of at least one kind of rubber and the styrene / vinyl isoprene / styrene copolymer. When the amount is less than 5 parts by weight, the reinforcing effect is small,
If it exceeds 20 parts by weight, the hardness becomes high, and the ratio of dynamic storage modulus E ′ _X , E ′ _Y / E ′ _X, which is the ratio of E ′ _Y , E ′ _Y , is also set to 0.
Beyond 5, it becomes an anisotropic material.

As the softener of the present invention, a softener for styrene / vinyl isoprene / styrene copolymer is used. This softener is incorporated into the styrene / vinyl isoprene / styrene copolymer to improve the damping performance.
The peak temperature of nδ is shifted to the lower temperature side. Examples of the softening agent include liquid rubber such as liquid polybutene and polyisoprene, or paraffin oil (SP value = 7.9) whose SP value is close to the SP value (8.2) of styrene / vinyl isoprene / styrene copolymer. , Naphthenic oil (SP value = 8.
2) and aroma oil (SP value = 8.7). The amount of the softener is not particularly limited.

As the softening agent for rubber, oils, plasticizers and the like having an SP value close to the SP value of the selected rubber are selected. For example, in the case of nitrile rubber, since the SP value is around 9.8, the ether ester plasticizer (S
P value = 8.9-9.2), DOP (SP value = 9.0),
A material having a value close to the SP value of rubber, such as DBP (SP value = 9.41), is selected. The amount of the softener is not particularly limited.

In the present invention, a peroxide as a crosslinking agent other than the above-mentioned additives can be added to form a gel material having a chemically crosslinked structure, so that it can be used at a high temperature. As the peroxide, for example, di-t-
Butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 2.5-dimethyl-2.
1. 5-di (t-butyl peroxide) -hexane;
5-dimethyl-2.5-di (t-butylperoxy)-
Hexane-3,1,3-bis- (t-butylperoxy-isopropyl) benzene, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane,
1,1-di-t-butylperoxycyclohexane,
N-butyl 4,4-di-t-oxyparerelate, 2,
2-di-t-butylperoxybutane is exemplified. Other crosslinking agents include azide-type crosslinking agents, phenol-type crosslinking agents, aldehyde-amine reaction products, sulfur, and maleic imides.

The impact-absorbing gel material of the present invention is not limited to a solid but may be a foam having an expansion ratio of 1.2 to 4. In this case, examples of the foaming agent include inorganic compounds such as sodium bicarbonate and ammonium carbonate, nitroso compounds such as dinitrosopentamethylenetetramine, azo compounds such as azodicarbonamide, azo-isobutyro-dinitrile, and other urea-based foaming aids. Agents can also be used.
The amount of the blowing agent added is styrene, vinyl isoprene,
It is 3 to 10 parts by weight based on 100 parts by weight of the styrene copolymer.

Further, in the present invention, the properties of the gel material can be improved by mixing an additive selected from a filler, a light stabilizer and a thermal oxidation inhibitor. As the filler, calcium carbonate, surface-modified calcium carbonate, silica,
Clay, talc and the like, and thermally expanded microcapsules such as polyacrylonitrile and vinylidene chloride, and hollow microsphere fillers obtained by foaming the above capsules and dusting with powders such as calcium carbonate and talc can be used.

[0022]

Next, the present invention will be described in more detail with reference to specific examples. Examples 1 to 3 and Comparative Examples 1 to 3 Compounds were prepared using a kneader. First, a styrene / vinyl isoprene / styrene copolymer shown in Table 1, a kind of rubber (NBR), a filler, a softening agent, a short fiber, and the like are charged and sufficiently mixed until the rubber temperature reaches 120 ° C. A peroxide and a crosslinking assistant were added to obtain a blend. The composition thus obtained was rolled to a thickness of about 2 mm on two rolls maintained at a roll temperature of 90 to 120 ° C. to obtain a sheet. This was cross-linked in a predetermined shape at 180 ° C. for 15 minutes to obtain a sheet having a thickness of 2 mm.

From the crosslinked and formed sheet, strip-shaped samples having a width of 10 mm, a length of 25 mm, and a thickness of 2 mm were prepared in the X-axis direction in the sheet extrusion direction and the Y-axis direction perpendicular to the sheet extrusion direction. The damping performance of this sample was adjusted to 1 to 100 Hz by using a rheograph solid (manufactured by Toyo Seiki Co., Ltd.) and applying a sinusoidal dynamic strain of ± 0.05% or less to the sample.
Is measured, and the maximum value of the loss coefficient tan δ is calculated as t
anδmax. The hardness was measured using a JIS-A type hardness meter. Adhesion was measured by pressing two samples having a width of 10 mm and a length of 50 mm, and measuring the 90 ° peeling force with a spring meter.
When the peeling force was less than 50 g / cm, the adhesiveness was judged as acceptable (合格), and when the peeling force exceeded 50 g / cm, it was judged as unacceptable (x).

[0024]

[Table 1]

According to the results, when the nitrile rubber is added, tackiness is completely eliminated, oil resistance is improved, and sufficient damping characteristics can be obtained. Further, by adding short fibers, there is a ratio of the dynamic storage modulus E _'Y / E' _X is in the range of 0.37 to 0.46, the short fibers become oriented close to random It turns out that there is.

[0026]

As described above, in the present invention, the styrene / vinyl isoprene / styrene copolymer having a styrene content of 30% or less is dispersed in a state of being surrounded by at least one kind of rubber, whereby the surface tackiness is reduced. And the styrene / vinyl isoprene / styrene copolymer incorporates a softener, which exhibits excellent damping performance, and polyamide,
One or two or more types of short fibers selected from rayon and cotton, or short fibers selected from mixed spun and mixed spun fibers are randomly oriented in each direction, so a high elastic modulus in each direction To maintain the tear resistance.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshihiro Yamada 4-1-1-21 Hamazoedori, Nagata-ku, Kobe Mitsusei Belt Co., Ltd. (72) Inventor Toru Noguchi 4-1-1, Hamazodori, Nagata-ku, Kobe-shi Mitsuboshi Belting Co., Ltd.

Claims (4)

[Claims] 1. A compound obtained by adding a crosslinking agent comprising a styrene / vinyl isoprene / styrene copolymer having a styrene content of 30% or less, a softener, a short fiber, and a peroxide to at least one rubber. Wherein a softener for styrene / vinyl isoprene / styrene copolymer is used as the softener, and at least one
30 to 70% by weight of styrene / vinyl isoprene / styrene copolymer with respect to 100 parts by weight of the total of the above rubbers and the styrene / vinyl isoprene / styrene copolymer, and one selected from polyamide, rayon and cotton Alternatively, a shock-absorbing gel material characterized by using 5 to 20 parts by weight of two or more kinds of short fibers or short fibers selected from mixed spun and mixed spun fibers. 2. The method according to claim 1, wherein the direction in which the short fibers are most oriented in the length direction of the shock absorbing gel material (X-axis direction) and the width direction perpendicular to the X-axis direction (Y-axis direction). each dynamic storage modulus E _'X, E' in the X-axis direction and the Y-axis direction of the absorbent gelling material is the ratio of _Y E _'Y / E' _X is 0.3
2. The impact-absorbing gel material according to claim 1, which is in the range of 0.5. 3. The impact-absorbing gel material according to claim 1, wherein a softener for rubber and a softener for styrene / vinyl isoprene / styrene copolymer are used in combination as the softener. 4. The impact-absorbing gel material according to claim 1, wherein the at least one rubber is a nitrile rubber.