JPH04304249A - Synthetic rubber composition - Google Patents

Abstract

PURPOSE:To obtain a synthetic rubber composition having a high loss factor and an excellent ability to absorb vibtational energy by mixing a nitrile rubber with a specified condensed polycyclic compound and/or a specified ring assembly in a specified ratio. CONSTITUTION:This composition is prepared by mixing 100 pts.wt. nitrile rubber (e.g. butadiene/acrylonitrile copolymer) with 5-100 pts.wt. condensed polycyclic compound having at least three rings (e.g. phenanthrene) and/or a ring assembly having at least three ring systems (e.g. 1,2-disphenylbenzene).

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention improves motion response speed and measurement accuracy, improves sound quality, and improves comfort by controlling vibration in fields such as precision electrical and electronic components, audio equipment, and automobiles. The present invention relates to a synthetic rubber composition with excellent vibration energy absorption performance, which is used for the purpose of improving vibration energy absorption performance.

0002

2. Description of the Related Art Conventionally, butyl rubber has been most commonly used as a vibration energy absorbing material. Generally, the primary evaluation of a vibration energy absorbing material is made by the storage modulus (E') and loss coefficient (tan δ = loss modulus/storage modulus (E'')) determined by measuring the viscoelasticity of the material.

[0003] In order to design a material as a vibration energy absorber, the larger the loss coefficient is, the more optimal the storage modulus is depending on the form in which it is used. These 2
Two factors are usually highly temperature dependent. That is, the storage modulus gradually decreases as the temperature increases, and usually decreases rapidly from a temperature range exceeding the glass transition point. Furthermore, although the loss coefficient shows the highest value in the temperature range exceeding the glass transition point, it generally tends to decrease in the temperature range around the glass transition point.

[0004] Accordingly, the standard required for such vibration energy absorbing materials has been that the material has a high loss coefficient in the temperature range in which it is used. On the other hand, the storage modulus can be adjusted over a wide range of values by adding inorganic or metal fillers, softeners, rubber, etc., so it has been possible to adjust it to the optimum value. Therefore, butyl rubber exhibits an excellent value of maximum loss coefficient of tan δ = 1.4.

[0005] Recently, it has been discovered that polynorbornene and special urethane elastomers have higher performance as vibration energy absorbers, and are attracting attention. However, these materials have difficulty in processability and economy compared to butyl rubber, and their range of use has been limited.

On the other hand, nitrile rubber is characterized by its particularly excellent oil resistance among synthetic rubbers. However, at present, it is hardly used as a vibration energy absorbing material like butyl rubber.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a synthetic rubber composition that has vibration energy absorption performance while taking advantage of the characteristics of nitrile rubber.

[0008]

[Means for Solving the Problems] In view of the above-mentioned current situation, the inventors of the present invention have made extensive studies and have completed the present invention.

That is, the present invention provides a fused polycyclic compound comprising three or more rings based on 100 parts by weight of nitrile rubber,
and/or ring sets 5 to 100 consisting of 3 or more ring systems
The present invention relates to a synthetic rubber composition comprising parts by weight, and further to a vibration energy absorbing material comprising the present composition. The details will be explained below.

The nitrile rubber used in the present invention is a butadiene-acrylonitrile copolymer, and is generally NBR.
Refers to what is called. However, if the amount of bound acrylonitrile exceeds 60%, it will become hard, and if it becomes less than 7%, it will swell in oil. Therefore, a rubbery, oil-resistant copolymer containing 15 to 50% acrylonitrile is preferred. Further, the polymerization reaction is carried out by emulsion polymerization, and the polymerization temperature ranges from cold rubber obtained at low temperatures to hot rubber obtained at room temperature or higher, and can be used without any particular problem. In addition, the Mooney viscosity (ML1+4 (100
C)) is preferably 20 to 90. Furthermore, N.B.
Copolymer of R and a small amount of acrylic monomer such as methacrylic acid (commonly referred to as carboxylated nitrile rubber)
Also included are copolymers with a third component, such as terpolymers with vinylpyridine.

Further, the fused polycyclic compound used in the present invention is a fused polycyclic hydrocarbon or a fused heterocyclic compound composed of three or more rings. There is no problem with any structure as long as there are three or more rings, but it is particularly preferable to have a large number of rings.

On the other hand, the ring assembly used in the present invention refers to a ring system in which three or more ring systems (single ring or condensed ring) are directly bonded through a single bond or double bond, and the number of such direct ring assembly is included. 1 less than the number of ring systems in the system. The ring system may be a cyclic hydrocarbon system or a heterocyclic ring system. Further, although there is no problem with any structure as long as it has three or more ring systems, it is particularly preferable to have a large number of ring systems.

These fused polycyclic compounds and ring assemblies (hereinafter collectively referred to as cyclic compounds) include alkyl groups having 1 to 4 carbon atoms, hydroxyl groups, oxo groups, carboxyl groups,
A functional group such as an amino group, a cyano group, a nitro group, or a halogen group may be bonded to the ring. Furthermore, since the cyclic material is to be composited with nitrile rubber, it is necessary to achieve a sufficient dispersion state. Therefore, it is desirable that the melting point of the cyclic material be lower than the crosslinking temperature of the nitrile rubber. For example, fused polycyclic compounds include acenaphthylene, acenaphthene, phenanthrene, 9-phenanthrol, fluorene, anthrone, 9-fluorenone, perhydrofluorenone, benzophenanthrene, 9-anthracenemethanol, 9
, 10-dihydroanthracene, pyrene, 1,2-benzopyrene, dibenzophenanthrene, dibenzosuberane, terpenes consisting of 3 or more rings, steroids, alkaloids, dibenzofuran, xanthene, 9-xanteno-
Examples thereof include xanthone, acridine, ibenzothiophene, phenanthridine, 1,4-benzoquinone, 7,8-benzoquinoline, 1,10-phenanthroline, phenandine, phenoxazine, thianthrene, and the like. As a ring assembly, 1,2-diphenylbenzene, 1,3
-diphenylbenzene, 1,3,5-triphenylbenzene, 1,2,3,4-tetraphenyl-1,3-cyclopentadiene, 2,2:6',2''-terpyridine, etc. One or more of the cyclic materials are combined with nitrile rubber.

[0014] From the viewpoint of processability and economy, the total amount of the annular substances is 5 parts by weight or more per 100 parts by weight of nitrile rubber.
00 parts by weight or less, more preferably 10 parts by weight or more and 50 parts by weight or less.

An example will be shown later, but for example, in the case of nitrile rubber with an acrylonitrile content of 33%, the frequency 1
When dynamic viscoelasticity is measured at 0 Hz, the maximum value of the loss coefficient is about 2.0 at about -2°C, but the maximum value of the loss coefficient varies from 2.1 to 2.0 depending on the amount added within this range. Shows about 9. According to relaxation phenomenology, this phenomenon is understood to be due to the homogenization of the internal state of the material and the narrowing of the relaxation time distribution, but it is unclear why such a particular ring is uniquely superior. It is.

Fillers such as carbon black, silicic acid, silicates, and magnesium oxide may be added to the synthetic rubber composition of the present invention for the purpose of improving mechanical and thermal properties. Furthermore, fillers such as calcium carbonate, and plasticizers such as organic esters and petroleum derivatives may be added for the purpose of improving processability and low-temperature properties. Furthermore, additives used in rubber such as anti-aging agents and anti-scorch agents can also be used. Also, if necessary, EPDM
, synthetic rubber such as halogenated butyl rubber, polyvinyl chloride, petroleum resin, etc. can also be blended.

The synthetic rubber composition of the present invention can be prepared using conventional vulcanization methods such as crosslinking agents such as sulfur, vulcanization aids such as zinc oxide, red lead, and lithium oxide, benzothiazole, dithiocarbamate, Vulcanization can be performed using a vulcanization accelerator such as thiuram. Therefore, injection molding, which is a conventional molding method,
It can be freely molded using techniques such as extrusion molding and calendering.

The vibration energy absorbing material obtained by the present invention can be used in places that require oil resistance or molded products used at low temperatures, and can also be blended with other resins or synthetic rubbers to improve vibration absorption performance at low temperatures. It can also be used for the purpose of improving. Furthermore, it can be applied directly to parts of automobiles and industrial equipment that experience strong vibrations to suppress vibrations, or it can be used in combination with other materials such as metal materials such as stainless steel plates and aluminum plates, wood, and inorganic materials. can.

[0019]

[Examples] The present invention will be explained below using examples.
The present invention is not limited to these examples.

Example 1 Butadiene-acrylonitrile copolymer (Europrene N
33.66, manufactured by Enichem Elastomeri) 100 parts by weight, 1.5 parts by weight of sulfur as a crosslinking agent, 3 parts by weight of zinc oxide as a vulcanization aid, zinc dimethyldithiocarbamate (Noxera-PZ, Ouchi) as a vulcanization accelerator Shinko Chemical Industry Co., Ltd.
) 0.7 parts by weight, further 1 part by weight of stearic acid,
50 parts by weight of bomb black and 10 parts by weight of phenanthrene as a condensed polycyclic compound were kneaded for 20 minutes on a water-cooled roll to obtain the desired composition.

Example 2 Pyrene 10 was used instead of phenanthrene in Example 1.
The desired composition was obtained by the same procedure except that parts by weight were used.

Example 3 The desired composition was obtained by the same procedure as in Example 1 except that 10 parts by weight of 1,2-diphenylbenzene was used as the ring assembly instead of phenanthrene.

Example 4 The desired composition was obtained by the same procedure as in Example 1 except that 10 parts by weight of 1,3-diphenylbenzene was used as a ring assembly instead of phenanthrene.

Example 5 The desired composition was obtained by the same procedure as in Example 1 except that 30 parts by weight of phenanthrene was used.

Comparative Example 1 The desired composition was obtained by the same procedure as in Example 1, except that only the fused polycyclic compound was removed from the formulation used in Example 1.

Comparative Example 2 The desired composition was obtained by the same procedure as in Example 1 except that 10 parts by weight of 2-methylnaphthalene was used instead of phenanthrene.

Comparative Example 3 The desired composition was obtained by the same procedure as in Example 1 except that 10 parts by weight of biphenyl was used instead of phenanthrene.

[Evaluation of loss coefficient (tan δ)] Example
The composition obtained in the comparative example was vulcanized using a press at a temperature of 180 DEG C. under a pressure of 100 kgf/cm@2 for 5 minutes to obtain a sheet with a thickness of about 200 .mu.m. The sheet obtained here is
Using a viscoelasticity analyzer RSAII (manufactured by Rheometrics First), which is a measurement device based on a non-resonant forced vibration method, the temperature was increased at a rate of 2°C/min. , measurement frequency 1
The loss factor was measured at 0 Hz. Table 1 shows the peak value of the loss coefficient at this time and the temperature at that time.

[0029]

[Table 1]

[0030]

As is clear from the above explanation, according to the present invention, a fused polycyclic compound consisting of nitrile rubber and three or more rings, and/or a ring assembly consisting of three or more ring systems can be specified. A vibration energy absorbing material having a high loss coefficient can be obtained by compounding at a ratio of .

Claims (2)

[Claims] Claim 1: A synthetic rubber composition comprising 5 to 100 parts by weight of a fused polycyclic compound comprising three or more rings and/or a ring assembly comprising three or more ring systems based on 100 parts by weight of nitrile rubber. . 2. A vibration energy absorbing material comprising the composition according to claim 1.