JPH01153739A - Vibration-proof rubber composition - Google Patents

Abstract

PURPOSE:To provide a rubber composition having a specific molecular structure attained by the polymerization in the presence of a specific metal catalyst and having excellent durability and vibration-proof property, i.e. vibration absorbing property. CONSTITUTION:The objective composition is composed mainly of an isoprene- butadiene copolymer produced by the polymerization in the presence of a lanthanide rare-earth metal catalyst and containing >=90% of cis-1,4 bond component, 10-95mol.% of isoprene unit and 90-5mol.% of butadiene unit. The metal catalyst is e.g. neodymium trichloride or trimethylaluminum.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a rubber component containing an isoprene-butadiene copolymer having a specific molecular structure as the main component, and having excellent durability and vibration damping properties. The present invention relates to a vibration-proof rubber composition.

[Conventional technology]

Conventionally, so-called anti-vibration rubber has been used to prevent noise and vibration from means of transportation such as automobiles and motorcycles, as well as from industrial machinery.

This type of anti-vibration rubber is generally required to have the following performance.

■It has a small vibration transmission coefficient, which means it has excellent anti-vibration performance.

■Excellent durability and fatigue performance.

■Less compression set, or set.

■Excellent vulcanization adhesion to metals.

Generally, natural rubber with excellent rubber elasticity is used as a vibration-proof rubber material, with varying amounts of fillers such as carbon blanks and vulcanizing agents depending on the various uses. However, there is a problem in that a large amount of carbon blank has a large effect on workability during kneading and molding, and the combination of fillers and vulcanizing agents alone does not meet the required performance, especially vibration damping performance and durability. There are limits to expression.

Under these circumstances, the rubber industry has traditionally focused on improving vibration-isolating performance by adding synthetic rubbers such as styrene-butadiene copolymer rubber and polybutadiene rubber, and various plasticizers to these vibration-isolating rubber materials. Attempts have been made to improve the required performance.

Recently, isoprene-butadiene copolymer rubber polymerized under lithium-based catalysts has been blended with natural rubber to improve vibration damping properties, compression set, etc.
Method for improving fracture characteristics (JP-A-57-128,726
A method has been proposed to improve crack growth resistance, which is a type of vibration damping performance and durability, by blending polybutadiene with a specific molecular structure with natural rubber (Japanese Patent Application Laid-Open No. 1983-1993). -138,244).

[Problem that the invention seeks to solve]

However, in all cases, the performance required for vibration-proof rubber, especially vibration-proofing performance and durability, has not been fully satisfied.

In particular, in the recent automobile industry, materials with high hardness are required as anti-vibration rubber itself becomes smaller, and requirements for anti-vibration performance and durability are becoming stricter year by year. The current situation is that there is a strong desire for the emergence of

The present invention was made against the background of the above-mentioned conventional technical problems, and an object of the present invention is to provide a vibration-isolating rubber composition particularly excellent in fatigue resistance and vibration-proofing performance, that is, in vibration-absorbing properties.

[Means for solving problems]

The present invention is obtained by polymerization in the presence of a lanthanum series rare earth metal catalyst, contains 90% or more of cis-1,4 bonds, and has an isoprene moiety of 10 to 95 mol% and a butadiene moiety of 90 to 5 mol%. The present invention provides a vibration-proof rubber composition containing an isoprene-butadiene copolymer as a main component.

The lanthanum series rare earth metal catalyst used in the production of the isoprene-butadiene copolymer of the present invention is, for example, (al
General formula LnYs (wherein, Ln is atomic number 57 in the periodic table)
-71 metal, Y is -R1-OR, -3R, -N
R2, phosphate, phosphite, X or RCOO-, where R is a hydrocarbon group having 1 to 20 carbon atoms, and X is a halogen atom) (referred to as "component (a)"), fb) general formula A
AR'R''R' (wherein R1, R2 and R3
are the same or different and are hydrogen atoms or hydrocarbon groups having 1 to 8 carbon atoms, and are not all hydrogen atoms (hereinafter referred to as "component (b)")
It is a catalyst system consisting of.

(Cl Lewis acid (hereinafter referred to as "component (C)") and/or (d) Lewis base (hereinafter referred to as "component (C)") as necessary.
(d) component").

First, in the ta) component, Ln is a lanthanum series rare earth element with an atomic number of 57 to 71 in the periodic table, and among them, cerium, lanthanum, praseodymium, neodymium, and gadolinium are preferable, and especially neodymium is industrially available. It is preferable because it is easy.

These rare earth elements may be a mixture of two or more.

Furthermore, Y is in the form of alkyl, alkoxide, thioalkoxide, amide, phosphate, phosphite, halogen, and carboxylate, with alkoxide, halide, and carboxylate being particularly preferred. this house,
As alkyl type compounds of lanthanum series rare earth elements,
It is represented by LnR3, and R is a group having 1 to 1 carbon atoms, such as a benzyl group, phenyl group, butyl group, or cyclopentadienyl group.
Twenty hydrocarbon groups may be mentioned.

The alcohol type compound (alkoxide) is represented by the general formula Ln (OR)3 (wherein Ln and R are the same as above), and preferable alcohols include 2-ethyl-hexyl alcohol, oleyl alcohol, stearyl alcohol, and phenol. , benzyl alcohol and the like.

The thioalcohol type compound (thioalkoxide) has the general formula Ln (SR)3 (wherein, Ln and R
is the same as above), and preferred thioalcohols include thiophenol.

As an amide type compound (amide), the general formula Ln (N
R2) s (wherein Ln and R are the same as above), and preferred amines include dioctylamine and dioctylamine.

The rare earth element phosphate is represented by \R' (in the formula, Ln is the same as above, and R and R' are the same or different, and is the same as R above), and is preferably tris (phosphoric acid). dihexyl) neodymium, and tris(diphenyl) neodymium phosphate.

The rare earth element phosphite has the general formula
R / Ln(OP)s \ R' (in the formula, Ln, R, R' are the same as above), preferably tris(dihexylsulfite) neodymium, tris[di(2sulfite) -ethylhexyl)] neodymium.

As a halogen type compound, the general formula LnX+ (in the formula, L
n is the same as above, X represents a halogen atom),
The halogen atom is preferably a chlorine atom, a bromine atom,
It is an iodine atom.

The rare earth element carboxylate has the general formula (RC
OO) 3L n, where R has 1 to 2 carbon atoms
0 hydrocarbon group, preferably a saturated or unsaturated alkyl group, linear, branched or cyclic, and the carboxyl group is bonded to a primary, secondary or tertiary carbon atom. It is something that exists. Specific examples of preferred carboxylic acids include octanoic acid, 2-ethyl-hexanoic acid, oleic acid, stearic acid, benzoic acid, and naphthenic acid.

Specific examples of these (Al components include neodymium trichloride, didymium trichloride (neodymium 72% by weight, lanthanum 2
mixture of rare earth metal trichlorides containing 0% by weight of praseodymium and 8% by weight of praseodymium), 2-ethylhexanoate/neodymium, 2-
Ethylhexanoic acid/didimium, naphthenic acid/neodymium, 2
, 2-diethylhexanoate/neodymium, neodymium trimethacrylate, neodymium trimethacrylate polymers, and the like.

The organic aluminum compound which is the component (b) has the general formula /I/! R'R2R' (Here, R11R2 and R3 are the same or different and have a hydrogen atom or a carbon number of 1
~8 hydrocarbon groups, not all of which are hydrogen atoms), specifically trimethylaluminum, triethylaluminum, triisopropylaluminum, tributylaluminum, triisobutylaluminum, trihexylaluminum, trihexylaluminum, Examples include cyclohexylaluminum, diisobutylaluminum hydride, diethylaluminum hydride, dipropylaluminum hydride, ethylaluminum sibide, propylaluminum sibide, isobutylaluminum sibide, and the like.

As the Lewis acid which is the component (C), for example, general formula A
Aluminum halide compound represented by I R' -X5-1I (wherein R4 is a hydrocarbon group having 1 to 8 carbon atoms, m is an integer of 0 to 3, and X is the same as above), a halogen element, and tin , halides such as titanium.

Among these, particularly preferred are dimethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, methylaluminum sesquichloride, ethylaluminum sesquibromide, ethylaluminum dichloride, and bromide and iodide compounds thereof.

(Lewis bases with a d+ acid component include acetylacetone, tetrahydrofuran, pyridine, N,N-dimethylformamide, thiophene, diphenyl ether, triethylamine, organic phosphorus compounds, and monohydric or dihydric alcohols.

The composition of the lanthanum series rare earth metal catalyst used in the present invention is usually as follows.

(bl component/(a) component (molar ratio) is 10 to 150,
Preferably it is 15 to 100; if it is less than 10, the polymerization activity is low, while if it exceeds 150, there is little effect on the polymerization activity, which is economically disadvantageous.

In addition, the (C) component/(a) component (molar ratio) is 0 to 6,
Preferably it is 0.5 to 5.0, and if it exceeds 6, the polymerization activity will decrease.

Furthermore, component (d)/component (a) (molar ratio) is 0 to 2
It is 0, preferably 1 to 15, and if it exceeds 20, the polymerization activity decreases, which is not preferable.

As catalyst components, the above (a), (b), (C), (dl
In addition to the ingredients, if necessary, conjugated diene may be added in an amount of 0 to 1 mole of the lanthanum series rare earth element compound (a).
It may be used in a proportion of 50 moles. The conjugated dienes used for catalyst preparation are isoprene, 1,3-butadiene, 1,3-
Pentagene and the like are used.

Although the conjugated diene is not essential as a catalyst component, the catalytic activity of the catalyst component is further improved by using it in combination.

To prepare the catalyst, e.g.
The process consists of reacting the dl component and, if necessary, a conjugated diene. At that time, the order of addition of each component may be arbitrary. It is preferable to mix, react, and age each of these components in advance in order to improve polymerization activity and shorten the polymerization initiation induction period. good.

Polymerization solvents include inert organic solvents, such as aromatic hydrocarbon solvents such as benzene, toluene, and xylene, aliphatic hydrocarbon solvents such as n-pentane, n-hexane, and n-butane, and methylcyclopenkune. , alicyclic hydrocarbon solvents such as cyclohexane, halogenated hydrocarbon solvents such as ethylene dichloride, chlorobenzene, and mixtures thereof.

The polymerization temperature is usually -20°C to 150°C, preferably 30 to 120°C. The polymerization reaction may be carried out batchwise or continuously.

Note that the monomer concentration in the solvent is usually 5 to 50% by weight,
Preferably it is 10 to 35% by weight.

The microstructure of the isoprene-butadiene copolymer obtained in this way requires that the cis-1,4 bonds in the isoprene structural unit and butadiene structural unit are each 90% or more; It has poor compatibility with other diene rubbers such as rubber, tends to have poor fracture properties, increases glass transition temperature, and may not be able to provide sufficient vibration damping properties.

In addition, the copolymerization ratio of isoprene and butadiene in the isoprene-butadiene copolymer, which is the main component of the present invention, is isoprene/butadiene (molar ratio) -10/95 to 9.
015, preferably about 30/70 to 90/10; outside this range, sufficient effects in terms of durability cannot be obtained.

The molecular weight of the isoprene-butadiene copolymer used in the present invention can be varied over a wide range, but when used as a vibration-proof rubber product, its Mooney viscosity (ML, 4.100°C) is Usually 10-12
0, preferably in the range of 15 to 100, but is not particularly limited.

In addition, the isoprene-butadiene copolymer used in the present invention may contain other conjugated dienes such as chloroprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and myrcene as necessary. It may be a rubber copolymerized to a degree of less than % by weight.

The anti-vibration rubber composition of the present invention has the above-mentioned isoprene-
The butadiene copolymer is the main component in the rubber component, and its proportion exceeds 90% by weight, preferably substantially 100% by weight, and if it is less than 90% by weight, the durability and In some cases, a sufficient improvement effect on vibration damping properties is not observed.

The isoprene-butadiene copolymer used in the present invention may contain other rubber components such as natural rubber and/or polyisoprene, as well as emulsion-polymerized styrene-butadiene copolymers, solution-polymerized styrene-butadiene copolymers, and low cis -1,4-polybutadiene, high-cis-1,4-polybutadiene, ethylene-propylene-diene copolymer, chloroprene, halogenated butyl rubber, NBR, etc. are used as a blend in an amount of less than 10% by weight in the rubber component. can do. Among these rubber components, it is particularly preferable to use it in a blend with natural rubber and/or polyisoprene.

The isoprene-butadiene copolymer of the present invention may be oil-extended with aromatic, naphthenic, or paraffinic oil, if necessary, and then carbon black, silica, etc.
Adding fillers such as magnesium carbonate, lucium carbonate, glass fiber, stearic acid, zinc white, anti-aging agents, vulcanization accelerators and vulcanizing agents,
It can be made into a vibration-proof rubber composition.

After molding, the resulting rubber composition is vulcanized and used in a wide range of anti-vibration applications such as automobile suspensions and engines, fenders for ships, and stoppers for precision positioning on assembly lines. It can be suitably used for various purposes.

〔Example〕

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

In the examples, parts and % mean parts by weight and % by weight unless otherwise specified.

Moreover, various measurements in the examples were based on the following methods.

Mooney viscosity was measured at a temperature of 100° C. after 1 minute of preheating and 4 minutes of measurement (according to JIS K6300).

The microstructure of the polymer was determined by infrared absorption spectroscopy (Morello method).

The tensile properties and hardness were measured according to JIS K6301 by vulcanizing a rubber composition according to the following formulation.

Mixed prescription (part) Polymer 100FEF carbon black 30 zinc white
5 stearic acid
1 Vulcanization accelerator cz
2 (cyclohexyl-benzothiazole-sulfenamide) sulfur 2 The extension fatigue test was performed using a Demasocha flexure tester, with 100% and 1
The material was repeatedly stretched and bent at 50% or 200% elongation, and evaluated by the number of times until cracking occurred.

The larger the number of times, the better.

The vibration damping properties were evaluated using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho, and the real part of the complex dynamic Young's modulus (E' (5Hz)) was measured at a frequency of 100Hz. The real part of the complex dynamic Young's modulus (E' (100Hz))
(static-dynamic ratio) (E'(100Hz＞/E'
(5Hz)), static dynamic ratio = CE' (100H2
)/E' (5H2)) is smaller, the better.

Reference Example 1 2,500 g of cyclohexane and 350 g of isoprene were placed in an autoclave with an internal volume of 51 cm and equipped with a stirrer under a nitrogen atmosphere.
and 150 g of 1,3-butadiene were charged and the temperature was adjusted to 60°C.

In a separate container, (a) neodymium 2-ethylhexanoate/(b)
) triisobutylaluminum/(C) diethylaluminum chloride/(d) acetylacetone (molar ratio)
A catalyst was prepared by adding and mixing at a ratio of 1/40/4/2 and aging at 50° C. for 30 minutes in the presence of a small amount of isoprene.

This aged catalyst was charged into the autoclave in an amount of 1 mole of G-dim atoms per 1.2 x 104 moles of isoprene and 1,3-butadiene monomers, and a polymerization reaction was carried out at 60°C for 7 hours. .

After confirming that the polymerization conversion rate is 100%, 2.
4 g of 6-di-t-butylcatechol and 5 ml of methanol
The reaction was terminated by adding a solution dissolved in . Then,
The obtained polymer solution was poured into methanol to recover the polymer, and then the polymer was dried in a vacuum dryer at 60° C. to obtain 480 g of polymer. The Mooney viscosity (ML++4.100°C) of this polymer was 50.

Table 1 shows the composition and microstructure of the obtained polymer (hereinafter referred to as "Polymer A").

Reference Examples 2 to 5 A polymerization reaction was carried out in the same manner as in Reference Example 1 except that the amounts of 1,3-butadiene and isoprene were changed, and polymer B
-E was obtained. The Mooney viscosity and microstructure of each of the obtained polymers are also shown in Table 1.

Reference Example 6 Isoprene homopolymer (
Polymer F) was obtained. The Mooney viscosity and microstructure of this polymer are shown in Table 1.

Examples 1 to 4 Polymers A to D obtained in Reference Examples 1 to 4 were each individually vulcanized according to the above-mentioned formulation, and the vulcanized physical properties of the vulcanized products are shown in Table 2.

Comparative Examples 1 to 3 Polymer E obtained in Reference Example 5 or Polymer F obtained in Reference Example 6 was used alone, or commercially available polybutadiene (manufactured by Japan Synthetic Rubber ■, BRol) and natural rubber (R
The blend system of 3S#3) was vulcanized according to the above-mentioned formulation, and the vulcanized physical properties of the vulcanized product are shown in Table 2. Example 1~
4 and Comparative Examples 1 to 3, it is clear that the rubber composition containing the isoprene-butadiene copolymer of the present invention as the main component is particularly superior to the conventional rubber composition containing polybutadiene, polyisoprene, etc. as the main component. It can be seen that it has excellent elongation fatigue performance and also has an excellent static-dynamic ratio.

〔Effect of the invention〕

The present invention is a vibration-proof rubber composition mainly composed of an isoprene-butadiene copolymer obtained using a lanthanum series rare earth metal catalyst, which has better fatigue resistance and anti-fatigue properties than known conjugated diene polymers. A vulcanizate with excellent vibration performance, that is, vibration absorption properties, can be obtained.

Patent applicant: Japan Synthetic Rubber Co., Ltd. Agent: Patent Attorney Takashi Shirai

Claims (1)

[Claims] (1) Obtained by polymerization in the presence of a lanthanum series rare earth metal catalyst, containing 90% or more of cis-1,4 bonds, and containing 10 to 95 mol% of isoprene moiety and 9% of butadiene moiety.
A vibration-proof rubber composition containing as a main component an isoprene-butadiene copolymer having 0 to 5 mol%.