JPS63297437A - Vibration-insulation rubber composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition having excellent vibration-absorption characteristics and fatigue resistance, by compounding an isoprene-butadiene copolymer with natural rubber and polyisoprene rubber at specific ratios. CONSTITUTION:The objective composition contains (A) 20-90pts.wt., preferably 30-80pts.wt. of an isoprene-butadiene copolymer containing >=90% of cis-1,4- bond and obtained by polymerizing monomer in the presence of a lanthanide rare earth metal catalyst (preferably a catalyst composed of a lanthanide rare earth metal compound and an organoaluminum compound) and (B) 80-10pts.wt., preferably 70-20pts.wt. of natural rubber and/or polyisoprene rubber.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method comprising an isoprene-butadiene copolymer obtained by polymerization in the presence of a lanthanum series rare earth metal catalyst, and natural rubber and/or polyisoprene rubber. This invention relates to a vibration-proof rubber composition with excellent vibration absorption properties and fatigue resistance properties.

[Conventional technology]

Conventionally, general-purpose anti-vibration rubbers have been manufactured using natural rubber, diene-based synthetic rubber alone or as a blend.

By the way, in recent years, with the development of the automobile industry,
The performance of anti-vibration rubber has come to require greater vibration-absorbing properties, and in particular there has been an increasing demand for anti-vibration properties even against low-frequency vibrations.

As one solution to this problem, it is known to blend a rubber component with a low glass transition temperature (Tg).

For example, attempts have been made to improve vibration damping properties by blending silicone rubber or polybutadiene rubber with natural rubber.

[Problem that the invention seeks to solve]

However, although these rubbers or rubber compositions improve the vibration damping properties at low frequencies, those containing conventional silicone rubber or polybutadiene rubber have inferior fatigue properties and cannot be put to practical use.

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-proof rubber composition that satisfies both vibration-proof properties and fatigue properties.

[Means for solving problems]

That is, in the present invention, (a) the cis-1°4 bond obtained by polymerization in the presence of a lanthanum series rare earth metal catalyst is
Isoprene-butadiene copolymer containing 20% or more
~90f! and (b) 80 to 10 parts by weight of natural rubber and/or polyisoprene rubber.

The lanthanum series rare earth metal catalyst used in the production of (a) isoprene-butadiene copolymer of the present invention has, for example, (a) the general formula LnY= (wherein, Ln has an atomic number of 57 to 71 in the periodic table). metal, Y is -R, -OR,S
R, NRt, phosphate, phosphite, X or RCO
O-, where R is a hydrocarbon group having 1 to 20 carbon atoms,
(X represents a halogen atom) (hereinafter referred to as "component (a)"), and (b)
General formula AfR'R"
-8 hydrocarbon groups, not all of which are hydrogen atoms) (hereinafter referred to as "component (b)")
It is a catalyst system consisting of

(C) 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 component (a), 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. This is preferred because it is easy to do.

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.

Among these, alkyl type compounds of lanthanum series rare earth elements are represented by LnRz, where R is a benzyl group,
Examples include hydrocarbon groups having 1 to 20 carbon atoms such as phenyl group, butyl group, and cyclopentagenyl group.

The alcohol type compound (alkoxide) is represented by the general formula Ln (OR) x (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.

As a thioalcohol type compound (thioalkoxide), the general formula Ln (SR)s C, in which Ln and R
is the same as above), and preferred thioalcohols include thiophenol.

As an amide type compound (amide), the general formula Ln (N
Rz ) s (wherein, Ln and R are the same as above)
Preferred amines include dioctylamine,
Dioctylamine is mentioned.

The rare earth element phosphate is represented by the general formula 0R Ln(OP)3 R' (wherein, Ln is the same as above, and R and R' are the same or different, and are the same as R above). Preferred examples include tris(dihexyl phosphate) neodymium and tris(diphenyl phosphate) neodymium.

As the rare earth element phosphite, −7″t
, R Ln(OP)s R' (in the formula, Ln%R%R' is the same as above), preferably tris(dihexylsulfite) neodymium, tris[di(2-sulfurous acid) ethylhexyl)] neodymium.

The halogen type compound has the general formula LnX.

(In the formula, Ln is the same as above, and X represents a halogen atom)
The halogen atom is preferably a chlorine atom,
They are bromine and iodine atoms.

The rare earth element carboxylate has the general formula (RC
OO)iLn, R is a hydrocarbon group having 1 to 20 carbon atoms, preferably a saturated or unsaturated alkyl group, and is linear, branched or cyclic, and the carboxyl group is It is bonded to a primary, secondary or tertiary carbon atom. Specific examples of preferred carboxylic acids include octanoic acid, 2-ethyl-hexanoic acid,
Examples include 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
0jiif%, praseodymium 8% by weight mixture of rare earth metal trichlorides), 2-ethylhexanoate/neodymium,
Examples include polymers of 2-ethylhexanoic acid/didimium, naphthenic acid/neodymium, 2,2-diethylhexanoic acid/neodymium, neodymium trimethacrylate, neodymium trimethacrylate.

The organoaluminum compound which is component Cb) has the general formula AIR'R''R' (where R1, R1 and R3 are the same or different, and has a hydrogen atom or a carbon number of 1 to 1).
8 hydrocarbon groups, not all of which are hydrogen atoms), specifically trimethylaluminum, triethylaluminum, triisopropylaluminum, tributylaluminum, triisobutylaluminum, trihexylaluminum, tricyclohexyl Examples include aluminum, diisobutylaluminum hydride, diethylaluminum hydride, dipropylaluminum hydride, ethylaluminum sibide, propylaluminum sibide, isobutylaluminum sibide, and the like.

(As the Lewis acid that is the C1 component, for example, the general formula Aj
! An aluminum halide compound represented by R', X*-- (wherein R4 is a hydrocarbon group having 1 to 8 carbon atoms, m is an integer of O 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, diptylaluminum chloride, methylaluminum sesquichloride, ethylaluminum sesquibromide, ethylaluminum dichloride, and bromide and iodide compounds thereof.

Examples of the Lewis base as component (d) 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.

The molar ratio of component (b)/component (a) is 10 to 150°, preferably 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 and it is economical. This is disadvantageous.

In addition, (C1 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, fd) component/(a) component (molar ratio) is 0 to 2
0, preferably 1 to 15, and if it exceeds 2o, the polymerization activity decreases, which is not preferable.

As catalyst components, the above (a), ('b), (C1, (d
In addition to component (a), if necessary, 0 conjugated diene may be added per mole of the lanthanum series rare earth element compound (a).
It may be used in a proportion of ~50 moles. Conjugated dienes used for catalyst preparation are isoprene, 1,3-butadiene, 1.3
- Pentagene etc. 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, for example, (a) to (
It consists of reacting component d) 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.

Examples of the polymerization solvent include inert organic solvents, such as aromatic hydrocarbon solvents such as benzene, toluene, and xylene, aliphatic hydrocarbon solvents such as n-pentane, n-hexane, n-buta7, and cyclohexane, and methyl. Alicyclic hydrocarbon solvents such as cyclobencune and cyclohexane, halogenated hydrocarbon solvents such as ethylene dichloride and chlorobenzene, and mixtures thereof can be used.

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 10-35%.

The microstructure of the isoprene-butadiene copolymer obtained in this way requires that the cis-1,4 bonds of the isoprene structural unit and the butadiene structural unit are each 90% or more; less than 90% ( (b) Compatibility with natural rubber is poor, and fracture properties tend to deteriorate (the glass transition temperature may rise, and sufficient vibration damping properties may not be obtained).

Note that the copolymerization ratio of isoprene and butadiene in the isoprene-butadiene copolymer that is component (a) of the present invention is usually isoprene/butadiene (molar ratio) = 20.
/80-9515, preferably 30/70-90/10
That's about it.

Further, 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 (ML1 + 4.100°C) is usually 10 ~12
0, preferably in the range of 15 to 100, but is not particularly limited.

(a) Isoprene-butadiene copolymer used in the present invention may optionally contain other conjugated dienes such as chloroprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and myrcene. It may be a copolymerized rubber of about 10% by weight or less.

The weight ratio of the above (a) isoprene-butadiene copolymer to (b) natural rubber and/or synthetic polyisoprene rubber (IR) is (a) 20 to 90 parts by weight, preferably 30 to 90 parts by weight. 80 parts by weight, (b) 80 to 10 parts by weight, preferably 70 to 20 parts by weight, and if component (a) is less than 20 parts by weight, sufficient improvement effect on vibration damping properties will not be seen; If the amount of the component exceeds 90 parts by weight, the effect of improving vibration damping properties is saturated, and on the contrary, fatigue resistance becomes worse.

Thus, in the present invention, (a) an isoprene-butadiene copolymer, and (b) natural rubber and/or IR
Furthermore, emulsion polymerized styrene-butadiene copolymer, solution polymerized styrene-butadiene copolymer, low cis-1,4
- polybutadiene, high cis-1,4-polybutadiene,
It is used by blending with ethylene-propylene-diene copolymer, chlorobrene, halogenated butyl rubber, NBR, etc. If necessary, it is extended with aromatic, naphthenic, or paraffinic oil, and then carbon black, silica, Add ordinary vulcanized rubber compounding agents such as fillers such as magnesium carbonate, calcium carbonate, and glass fiber, stearic acid, zinc white, anti-aging agents, vulcanization accelerators, and vulcanizing agents to form a vibration-proof rubber composition. be able to.

After molding, the resulting rubber composition is vulcanized and is suitable for a wide range of vibration-isolating applications, including vibration-isolating applications such as around automobile engines, fenders for ships, and stoppers for precision positioning on assembly lines. It can be used for.

〔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.

In addition, various measurements in the examples were performed according to the following methods. Mooney viscosity was measured at a temperature of 100° C. with 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 JTS K6301 after vulcanizing a rubber composition according to the following formulation.

The extension fatigue test was carried out using a Dematcher bending tester with a
A dragon cut was made and the material was repeatedly stretched and bent at 50% or 100% elongation, and evaluation was made based on the number of times it took to break, as well as the number of times it was made to repeatedly extend and bend at 100% elongation without making a cut until it was cut.

The larger the number of times, the better.

The vibration damping properties were evaluated by determining the static shear modulus Gs of the vulcanizate according to JIS K6301, and by determining the real number of complex dynamic Young's modulus measured at a frequency of 5 Hz using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho. (Static dynamic ratio) (E'
(100Hz)/E'(5H2)), and the larger Gs is, the static dynamic ratio = (E'(100Hz)/
E' (5Hz)) is smaller, the better.

y Planned recipe (part) Polymer 100FEF carbon black 3゜zinc white
5 stearic acid
l Vulcanization accelerator CZ
2 (Cyclohexyl-Benzothiazole-Sulfenamide) Sulfur 2 Reference Example 1 2.500 g of cyclohexane and 350 g of isoprene were placed in an autoclave with an internal volume of 51 mm and equipped with a stirrer under a tin atmosphere.
and 150 g of 1,3-butadiene were charged and the temperature was adjusted to 60°C.

In a separate container, add and mix (a) neodymium 2-ethylhexanoate/(t)) triisobutylaluminum/(C) diethylaluminum chloride/(d) acetylacetone (molar ratio) = 1/40/4/2. The catalyst was prepared by 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 neodymium atoms per 1.2×10' moles of monomers of isoprene and 1,3-butadiene, 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 to 5 m of methanol
The reaction was terminated by adding a solution dissolved in j2.

The resulting polymer solution was then poured into methanol,
The polymer was collected and then dried in a vacuum dryer at 60° C. to obtain 480 g of polymer. The Mooney viscosity (M L + or 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-D obtained in Reference Examples 1 to 4 and natural rubber (
NR) was vulcanized according to the above-mentioned formulation, and the vulcanized physical properties of the vulcanized product are shown in Table 2.

Comparative Examples 1 to 3 Polymer E obtained in Reference Example 5, Polymer F obtained in Reference Example 6, commercially available polybutadiene (manufactured by Japan Synthetic Rubber Co., Ltd.,
BROI) was vulcanized according to the above-mentioned formulation, and the vulcanized physical properties of the vulcanized product are shown in Table 2.

From Examples 1 to 4 and Comparative Examples 1 to 3, the rubber composition blended with the isoprene-butadiene copolymer of the present invention has the same or higher elongation fatigue compared to conventional polybutadiene and polyisoprene. It can be seen that the braking ratio is excellent.

Comparative Example 4 Using 10 parts by weight of Polymer A obtained in Reference Example 1 and 90 parts by weight of natural rubber as rubber components, the vulcanized product was vulcanized according to the formulation shown in Table 2. Shown in Table 2.

(The following is a blank space) [Effects of the Invention] The present invention provides a rubber composition containing an isoprene-butadiene copolymer obtained using a lanthanum series rare earth metal catalyst and natural rubber and/or polyisoprene rubber in a specific ratio. Therefore, a vulcanizate having superior vibration absorption properties and fatigue resistance properties compared to known conjugated diene polymers can be obtained.

Claims (1)

[Claims] (1) (a) 20 to 90 parts by weight of an isoprene-butadiene copolymer containing 90% or more of cis-1,4 bonds obtained by polymerization in the presence of a lanthanum-based rare earth metal catalyst; and (b) a natural Rubber and/or polyisoprene rubber8
A vibration-proof rubber composition comprising 0 to 10 parts by weight.