JP2802041B2 - Shock absorbing gel composition - Google Patents

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 composition, and more particularly to a high-damping region having a large damping performance near room temperature and having a high damping performance at 20.degree. The present invention relates to a shock-absorbing gel composition which straddles the above and has excellent creep resistance.

[0002]

2. Description of the Related Art Rubber, asphalt, and the like have been well known as shock absorbing and damping materials 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, and the glass transition point near room temperature,
In addition, the tan δ value is set 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 large damping performance. However, since a large damping peak near room temperature is sharp, the temperature of the damping performance is low. In addition, there is a problem that the dependence on the frequency is increased. In addition, this shock absorber applied a constant load for a long time, and after the load was removed, a large permanent distortion remained, causing a problem of lack of creep resistance. Also, the silicone gel has a tan δ value of 0.2.
0.8, which is not only low in damping performance as compared with polynorbornene, but also has problems such as too low elastic modulus and high cost. The present invention has been made to solve such problems, and has a glass transition point near room temperature, has a large damping performance over a wide temperature range around room temperature, and has excellent creep resistance. An absorbent gel composition is provided.

[0004]

According to the present invention, there is provided a styrene / vinyl isoprene / styrene copolymer having a styrene content of not more than 30% by weight and an average molecular weight of at least 8 per 100 parts by weight.
A reinforcing agent and a crosslinking agent are added together with 10 to 500 parts by weight of liquid polybutene of 100 to 3,000, and the amount of the reinforcing agent is X (parts by weight), and the amount of the crosslinking agent is Y (parts by weight). Then, X and Y are represented by the following three inequalities: Y <0.05X + 0.25 2.0.25 <Y <1.25 3.5 <X <35 The impact-absorbing gel composition satisfies the following condition.

In the present invention, the crosslinking agent is a peroxide, the reinforcing agent is carbon black, or the liquid polybutene has an average molecular weight of 800 to 3,000.
And a mixture of liquid polybutene having an average molecular weight of 800, a liquid polybutene having an average molecular weight of 1,400, and a liquid polybutene having an average molecular weight of 2,900 as liquid polybutene. .

The present invention further relates to a method of adding 5 to 100 parts by weight of a ceramic powder selected from boron nitride and yttrium oxide to 100 parts by weight of a styrene / vinyl isoprene / styrene copolymer having a styrene content of 30% or less. Or when additives selected from light stabilizers, thermal antioxidants, and surfactants are mixed in, or when the vinyl isoprene phase of styrene / vinyl isoprene / styrene copolymer is hydrogenated including.

That is, in the present invention, the glass transition region of a styrene / vinyl isoprene / styrene copolymer having a sharp glass transition region (sharp tan δ peak region) from room temperature to a slightly higher temperature side at about 30 ° C. These problems have been solved by adding polybutene having an average molecular weight of 800 to 3,000 in order to increase the tan δ value on the high-temperature side. Further, by adding the same, the hardness of the styrene / vinyl isoprene / styrene copolymer was reduced, and a shock absorbing gel composition capable of absorbing low frequency vibration was obtained.

The resulting shock-absorbing gel composition has at least a maximum value of tan δ of 1 or more, and has a glass transition region (peak region of tan δ) around room temperature (20 to 30 ° C.).
C), and the high attenuation region (tan δ ≧ 1) is 20 ° C.
It has a characteristic that the tan δ value on the high temperature side increases over the above. That is, 1. tanδmax ≧ 1 2. Temperature (tan δmax) = 25 ± 5 ° C 3. 3. Temperature (tan δ ≧ 1) ≧ 20 ° C. tan δ (50 ° C) ≧ 0.4

Further, the impact-absorbing gel composition of the present invention comprises:
It has small and stable frequency dependence of the storage elastic modulus E 'around room temperature, that is, it has the following characteristics. 5. E ′ (100 Hz) / E ′ (1 Hz) <10

Further, the impact-absorbing gel composition of the present invention comprises:
The frequency dependence of tan δ near room temperature is small and stable, that is, it has the following characteristics. 6. tan δ (100 Hz) / tan δ (1 Hz) <4 Therefore, the impact-absorbing gel composition of the present invention has at least the above properties 1 to 4, and satisfies all of the properties 1 to 6. Is also good.

Further, in the impact-absorbing gel composition to which a ceramic powder selected from boron nitride and yttrium oxide is added, the peak half width of tan δ is 40 ° C. or more, and the large damping performance is obtained over a wider temperature range. It becomes what has. That is, it has the following characteristics. 7. Peak width at half maximum of tan δ ≧ 40 ° C.

Further, in the present invention, in addition to the above characteristics, the creep resistance is improved. This improvement in creep resistance is achieved by the following three inequalities where X and Y are as follows, where X (parts by weight) of the reinforcing agent and Y (parts by weight) of the crosslinking agent: Y <0.05X + 0.25 2.0.25 <Y <1.25 3.5 <X <35 This is improved by increasing the amounts of the reinforcing agent and the crosslinking agent so as to satisfy the following condition. However, when the crosslink density is higher than the degree of reinforcement, the gel composition becomes brittle, and conversely, when the degree of reinforcement is higher than the crosslink density, the hardness of the gel composition increases. That is, the increase in the crosslink density and the degree of reinforcement are both ta.
It lowers nδ and lowers impact absorption performance. If the addition amounts of X and Y satisfy the above three inequalities, t
does not significantly reduce anδ.

The styrene / vinyl isoprene / styrene copolymer used in the impact-absorbing gel composition of the present invention comprises a triblock copolymer in which polystyrene and vinyl-polyisoprene are bonded, and has a styrene content of 30%. It is as follows. This copolymer has a glass transition temperature in the room temperature region, and has high attenuation performance in this temperature range. However, since the peak region of tan δ is sharp, the attenuation performance near room temperature depends on temperature and frequency. Great nature. If the styrene content exceeds 30%, the rigidity of the copolymer increases, and it becomes difficult to control the hardness of the gel composition.

As the above-mentioned styrene / vinyl isoprene / styrene copolymer, those in which the vinyl isoprene phase is hydrogenated can also be used. In this case, the hydrogenation rate is 80% or more.

Since the polybutene used in the present invention has a flow region having a very large tan δ value near room temperature, the glass transition region (peak region of tan δ) of the styrene / vinyl isoprene / styrene copolymer as described above.
And increases the tan δ value on the high-temperature side, and reduces the hardness to enable absorption of low-frequency vibrations. For this reason, the average molecular weight of polybutene is limited to 800 to 3,000.

When the average molecular weight is less than 800, the glass transition region shifts to a low temperature as in the case of ordinary plasticizers such as oils, whereas when it exceeds 3,000 or becomes solid, the gel composition becomes too low. The decrease in hardness of the object is small, the glass transition region does not spread to the low temperature side, and a desired damping material cannot be obtained. In particular, when liquid polybutene having an average molecular weight in the range of 800 to 3,000 and different molecular weights is mixed, the width of the high attenuation region is very wide, and the peak half width of tan δ is also large.

The amount of the polybutene added is 10 to 5
00 parts by weight. If the amount is less than 10 parts by weight, the temperature range in which the glass transition region can be used is widened, and the transition region is not sufficiently widened and the hardness is lowered. The properties are large, and physical properties such as compression deformation are also reduced. Of course, in the present invention, a mixture of liquid polybutene having an average molecular weight in the range of 800 to 3,000 and having different molecular weights can also be used.

However, in the present invention, it is necessary to add a crosslinking agent and a reinforcing agent. The crosslinking agent used here is a peroxide, for example, di-t-butyl peroxide,
t-butyl cumyl peroxide, dicumyl peroxide, 2.5-dimethyl-2.5-di (t-butyl peroxide) -hexane, 2.5-dimethyl-2.5-
Di (t-butylperoxy) -hexane-3,1,3-
Bis- (t-butylperoxy-isopropyl) benzene, 1,1-di-t-butylperoxy-3,3,5-
Examples thereof include trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, n-butyl 4,4-di-t-oxyparerelate, and 2,2-di-t-butylperoxybutane.

The reinforcing agent is carbon black having an average particle diameter of 30 to 120 nm, preferably 5 to 120 nm.
It is preferably from 0 to 100 nm. Examples thereof include furnace black, acetylene black, thermal black, and channel black, which are commonly used.

When the addition amount of the reinforcing agent is X (parts by weight) and the addition amount of the crosslinking agent is Y (parts by weight), X and Y are the following three inequalities: It is necessary to satisfy Y <0.05X + 0.25 2.0.25 <Y <1.25 3.5 <X <35. X and Y satisfying these are trapezoidal regions as shown in FIG. The amount X of the reinforcing agent added is 5
If the amount is less than 35 parts by weight, the creep elongation of the gel composition is increased and the creep resistance is lacking. On the other hand, if the amount is more than 35 parts by weight, the hardness increases and the decrease in tan δ tends to increase. When the amount Y of the crosslinking agent is 0.25 parts by weight or less, the gel composition lacks creep resistance.
When the amount is more than the weight part, the gel composition becomes brittle, and when a constant load is applied, the gel composition is cut (creep cut), and the reduction of tan δ increases.

Further, in the present invention, a ceramic powder selected from boron nitride having a relatively large particle size as compared with carbon black and the like and yttrium oxide can be added to the above-mentioned impact-absorbing gel composition. This ceramic powder has a characteristic in surface shape, and has a very high friction with the molecules of the composition, thereby increasing the damping performance particularly in both the low temperature side and the high temperature side of the glass transition region.

For example, boron nitride powder or yttrium oxide powder has a plate-like structure and has a large number of sharply-angled irregularities on its surface, which increases the internal frictional force between the interface with the polymer and increases the composition. When the object is subjected to vibration, internal heat is easily generated between the interfaces, and the damping performance increases. Therefore, the specific ceramic powder can widen the high attenuation region without significantly increasing the hardness unlike carbon black in which the fine particles easily form a structure.

The above ceramics is used in an amount of 5 to 100 parts by weight of styrene / vinyl isoprene / styrene copolymer.
100 parts by weight are added. When the amount is less than 5 parts by weight, there is no effect of widening the high attenuation region. On the other hand, when the amount exceeds 100 parts by weight, the hardness of the gel composition becomes extremely high, and the desired gel composition cannot be obtained.

Further, in the present invention, in addition to the above-mentioned styrene / vinyl isoprene / styrene copolymer, polyvinyl acetate having a glass transition region near room temperature or polyvinyl chloride plasticized with a plasticizer may be blended. it can. The addition amount is 5 to 50 parts by weight based on 100 parts by weight of the styrene / vinyl isoprene / styrene copolymer.

Further, the impact-absorbing gel composition of the present invention comprises:
The foam is not limited to a solid but may be a foam having an expansion ratio of 1.2 to 4. In this case, as a blowing agent, inorganic compounds such as sodium bicarbonate and ammonium carbonate, dinitroso.
Nitroso compounds such as pentamethylene / tetramine, azo compounds such as azodicarbonamide, azo / isobutyro / dinitrile, and other urea-based foaming assistants can also be used. The amount of the foaming agent is 3 parts per 100 parts by weight of the styrene / vinyl isoprene / styrene copolymer.
To 10 parts by weight.

Further, in the present invention, the properties of the gel composition can be improved by mixing an additive selected from a light stabilizer, a thermal antioxidant and a surfactant. Examples of the light stabilizer include 2-hydroxy-4-methoxybenzophenone, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, -Tert-butylphenyl-3 ', 5'-di-tert-butyl-4'-hydroxybenzoate, nickel dibutyl-dithiocarbamate and the like. The amount of light stabilizer added is
It is 0.2 to 5 parts by weight based on 100 parts by weight of the vinyl isoprene / styrene copolymer.

As the thermal oxidation inhibitor, for example,
6-di-tert-butyl-4-methylphenol, styrenated phenol, mixed N, N'-diallyl-paraphenylenediamine, dilauryl-3,3'-
Thiodipropylate, distearyl-3,3'-thiodipropylate, trinolylphenylphosphate, N
-Phenyl-N'-isopropyl-P-phenylenediamine and the like are used. The added amount of this thermal antioxidant is
Styrene / vinyl isoprene / styrene copolymer 100
It is 0.2 to 5 parts by weight based on parts by weight.

Surfactants are used to prevent sticking on the surface of the obtained gel composition. Examples thereof include anionic surfactants such as sodium alkyl sulfate and sodium dialkyl sulfosuccinate, and alkylpyridinium sulfates. Nonionics such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, sorbitan tristearate, sorbitan monooleate and sorbitan trioleate; amphoteric such as alkyltrimethylaminoacetic acid There is something. The addition amount of this surfactant is
It is 0.2 to 5 parts by weight based on 100 parts by weight of the vinyl isoprene / styrene copolymer.

[0029]

Next, the present invention will be described in more detail with reference to specific examples. Examples and Comparative Examples The temperature of the mixer vessel was kept at 150 ° C., and a mixture of solid styrene-vinylisoprene-styrene copolymer (SVIS) and liquid polybutene shown in Tables 1 and 2 was heated to 150 ° C. Into a mixer maintained at
After the VIS is melted, the other ingredients shown in Table 1 are mixed and thoroughly mixed. The mixture thus obtained was rolled to about 2 mm with two rolls maintained at a roll temperature of 90 to 120 ° C.
To obtain a sheet. This was crosslinked into a predetermined shape at 170 ° C. for 15 minutes and molded.

10 m width from the crosslinked and molded sheet
A strip-shaped sample having a length of 20 mm, a length of 20 mm, and a thickness of 2 mm was prepared. The damping performance of this sample was determined by applying a rheographic solid (manufactured by Toyo Seiki Co., Ltd.) to a sinusoidal dynamic strain of ± 0.05% or less. E ″ and loss factor tan δ were measured.
max is a maximum value measured in a temperature range of -40 ° C to 60 ° C at a frequency of 10 Hz. The temperature dependence was measured at a frequency of 10 Hz in a temperature range of -40 ° C to 60 ° C, and the frequency dependence was measured at 25 ° C in a frequency range of 1 to 100 Hz.

Further, the creep permanent elongation was measured at an ambient temperature of 7
At 0 ° C., 2.5 kgf / cm
After giving ² load 2 hours, to remove the load, and measuring the length after creep. The creep permanent elongation (%) was determined by (length after creep−length before creep) / length before creep × 100. These measurement results are also shown in Tables 1 and 2.

[0032]

[Table 1]

[0033]

[Table 2]

According to the results, the temperature region (high attenuation region) where the damping performance represented by tan δ ≧ 1 is extremely large in both the example and the comparative example is widened, and the maximum value of tan δ is also large. Moreover, the storage modulus E ′ and tan
It can be seen that the frequency dependence of δ is also stable. But,
Comparing the example and the comparative example, it can be seen that in the example, the creep permanent elongation is small and the creep resistance is excellent, but in the comparative example, the creep permanent elongation is large and the creep test was broken.

[0035]

As described above, the impact-absorbing gel composition of the present invention can absorb impact over a wide temperature range around room temperature, and has a storage modulus E ′ and tan δ near room temperature. Is stable, so that it has the effect of absorbing vibrations having a wide range of frequencies and has the effect of being excellent in creep resistance.

[Brief description of the drawings]

FIG. 1 is a graph showing an appropriate amount range of the amount of carbon black to be added and the amount of a crosslinking agent in the impact-absorbing gel composition of the present invention.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 23/20 C08L 23/20 (72) Inventor Toru Noguchi 4-1-1-21 Hamazoedori, Nagata-ku, Kobe Mitsuboshi Belting Co., Ltd. Examiner Tsutomu Onodera (56) References JP-A-2-209936 (JP, A) JP-A-3-166247 (JP, A) JP-A-5-320429 (JP, A) JP-A-1-139634 ( JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C08L 53/00 C08L 23/20 C08K 3/04 C08K 3/22 C08K 3/38 C08K 5/14 C08J 3/24

Claims (8)

(57) [Claims] A styrene having a styrene content of 30% or less.
A reinforcing agent and a crosslinking agent are added together with 10 to 500 parts by weight of liquid polybutene having an average molecular weight of 800 to 3,000 with respect to 100 parts by weight of the vinyl isoprene / styrene copolymer, and the amount of the reinforcing agent is X ( X) and Y are the following three inequalities when the amount of the crosslinking agent is Y (parts by weight). A shock-absorbing gel composition characterized by satisfying Y <0.05X + 0.25 2.0.25 <Y <1.25 3.5 <X <35. 2. The impact-absorbing gel composition according to claim 1, wherein the crosslinking agent comprises a peroxide. 3. The impact-absorbing gel composition according to claim 1, wherein the reinforcing agent is carbon black. 4. The impact-absorbing gel composition according to claim 1, wherein liquid polybutene having an average molecular weight in the range of 800 to 3,000 and different molecular weights is mixed. 5. A liquid polybutene having an average molecular weight of 80.
The impact-absorbing gel composition according to claim 4, wherein 0 liquid polybutene, 1400 average molecular weight liquid polybutene, and 2900 average molecular weight liquid polybutene are mixed. 6. A styrene / vinyl isoprene / styrene copolymer 1 having a styrene content of 30% or less, comprising a ceramic powder selected from boron nitride and yttrium oxide.
The impact-absorbing gel composition according to claim 1, wherein 5 to 100 parts by weight are added to 00 parts by weight. 7. The impact-absorbing gel composition according to claim 1, wherein an additive selected from a light stabilizer, a thermal antioxidant, and a surfactant is mixed. 8. The impact-absorbing gel composition according to claim 1, wherein the vinyl isoprene phase of the styrene / vinyl isoprene / styrene copolymer is hydrogenated.