JPS62292844A - Vulcanized rubber - Google Patents

Abstract

PURPOSE:To obtain a vulcanized rubber having excellent impact resilience and flexing resistance, by vulcanizing a compsn. comprising a specific raw material rubber, a filler, sulfur and a vulcanizing accelerator. CONSTITUTION:A compsn. obtd. by compounding 100pts.wt. raw material rubber contg. not less than 30wt% branched polybutadiene rubber obtd. by polymn. using a lithium base catalyst (e.g. n-propyl-lithium) and then by coupling reaction with a branching agent (e.g. tetrachlorosilane) having 0.2-1.5 equivalent wt. to the catalyst whose weight-average MW (MW) measured by gel permeation chromatography is 50,000-500,000, having a monomodal MW distribution where the ratio of MW to number-average MW is 1.5-4.0, whose Mooney viscosity (ML) measured at 100 deg.C by using an L rotor is 20-90, whose soln. viscosity (SV) in 5wt% styrene at 25 deg.C is 20-100 cps and where the relation of (ML) and (SV) satisfies formula I, with 20-150pts.wt. filler, sulfur in doubled quantity (pts.wt.) of formula II of a straight chain polybutadiene rubber in which log SV/log MW relation is 1.30-1.35 and vulcanizing accelerator, is vulcanized at 130-200 deg.C to obtain a vulcanized rubber whose impact resiliences measured at 70 deg.C and 20 deg.C satisfy formula III.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is made by vulcanizing a composition containing a specific highly branched polybutadiene rubber as the main raw material rubber, which has excellent crack growth resistance and rubber elasticity. Regarding vulcanized rubber with excellent properties.

[Conventional technology and its problems]

Polybutadiene rubber is obtained by polymerizing butadiene using a lithium-based catalyst and using a Ziegler-based catalyst containing nickel, cobalt, titanium, or lanthanide metals as the main components. High-cis polybutadiene rubber is known, and these rubbers have superior dynamic properties compared to rubber, and have been widely used in various rubber applications (- especially in tire applications) by taking advantage of their abrasion resistance and low rolling properties. It has been applied to various parts such as the tread part, side fall part, carcass part, and peal part.

However, conventional polybutadiene rubber has low fracture properties and inferior crack growth resistance, represented by flex resistance, compared to other diene rubbers, so its use is naturally limited, and the blend ratio However, the current situation is that a satisfactory polybutadiene rubber has not yet been obtained. Various proposals have been made to improve this drawback; for example, an improvement using polybutadiene having an average chain length of 7,9 bonds at a specific node has been proposed. However, the improvement itself is still insufficient;
Furthermore, it is difficult to obtain this polybutadiene due to the use of a special catalyst with low polymerization activity, and further improvements are desired in the industrial field.

[Problem that the invention seeks to solve]

The present invention is characterized by improving the above-mentioned drawbacks of polybutadiene rubber.
The purpose is to improve on two points.

[Means for solving problems]

That is, the present invention has (1)! J lithium-based catalytic polymerization and further (obtained using 0.2 to 1.! equivalents of branching agent with respect to the 2 lithium-based catalysts) measured by gel permeation chromatography. It has a monomodal molecular weight distribution with a weight average molecular weight of j-jO, and a ratio of weight average molecular weight to number average molecular weight of 8j to 9.0, b) using an L rotor at 100°C
The Mooney viscosity [:ML) measured at 2θ~ri. , C
), at 25°C, ! heavy ffi% styrene solution viscosity (
SVI is 2o to 100 centivoise d) The relationship between the above [ML] and [sV] satisfies the following formula l■Sv 0, ♂2≦□≦1. /♂ 10gM L Raw material rubber containing at least 30% by weight of branched polybutadiene rubber, 10oM@part (2) Filler, 2o~/jo parts by weight (3) Iota and vulcanization accelerator, k SV/lo+r The relationship between M and L is 7.30 to 1.
3 f-type multimeter (parts by weight) log M L of the amount used in the linear polybutadiene rubber called j.

1.25-io, 2oC made by vulcanizing lJi's own material consisting of Kosek SV, and 2! The rebound elasticity (JIS) measured at ℃ is calculated by the formula -F.
#7 Provide the person in charge.

The present invention will be explained in detail below.

The branched polybutadiene rubber used as the main component of the raw material rubber in the present invention is solution polymerized using a lithium-based catalyst. Examples of lithium-based catalysts include n-propyllithium, isopropyllithium, n-butyllithium, 5ee-butyllithium, t-butyllithium, n-pentyllithium, lithium toluene, pentyllithium, 1. Kujirithio-lobtan, 1.2
- Dilithio 1.2 diphenylethane, trimethylene dilithium, oligoisoprenyl dilithium, etc.
Particularly preferred are n-butyllithium and crown-butyllithium. Alternatively, modified catalysts may be used, in which polar compounds such as amines and ethers are added. Furthermore, the polybutadiene rubber is polymerized using the lithium-based catalyst mentioned above (2), and then treated with the lithium-based catalyst at 01.
It is obtained by carrying out a so-called coupling reaction using 2 to 3 equivalents of a branching agent. The branching agent herein refers to a polyfunctional reagent whose functional group is tri-functional or more, preferably g-functional or more, and has reactivity with lithium.

Specifically, tetrachlortin, hexachlorcinrane, pentachlormethyldisilane, tetrachlordimethyldinrane, hexachlordimethylenedisilane, hexabromosilane, tetrachlortin, tetraiodotin,
Polynogen compounds such as carbon tetrachloride, diesters such as diethyl adipate and diphenyl carbonate, and tetraglyphyl/. In molecules such as 3-pisaminomethylcyclohexane (-compounds having two or more diglyndylamino groups, polyepoquine compounds such as epoxylated liquid polybutadiene, diacylno-1lides such as ethylene dicarbonyl chloride and phthaloyl dichloride, Examples include pyridines such as meta- or para-pyridinecarboxylic acid, and particularly preferred are tetrachlortin, hexachlorodisilane, and tetraglyphyl/3-bisaminomethylcyclohexane.

When the functionality of the branching agent reagent is less than 3, it is difficult to obtain a polybutadiene rubber having the specified structure of the present invention in terms of branching efficiency. In addition, such polybutadiene rubber does not exhibit the excellent crack growth effect of the present invention. Generally, when 1 mole atom of lithium reacts with 7 moles of functional group atoms, it is an equivalent reaction, and therefore, 1 mole of lithium-based catalyst and 1 mole of branching agent having n functional groups are equivalently reacted.In the case of the present invention, the amount of branching agent used depends on the lithium-based catalyst used. for,
0.2 to 7.5 wax. 0. If the amount is less than coequivalent, the effect as a branching agent, for example, branching efficiency may not be sufficient; Using a size exceeding the Ji equivalent is not only unnecessary but also industrially disadvantageous. The amount of branching agent necessary and sufficient to obtain a polybutadiene rubber having the structure specified in the present invention is within the above-mentioned range, and preferably has a lithium-based catalyst. This is the case when the amount is 0.q to 8-equivalent.

In the case of polybutadiene rubber obtained using the above-mentioned branching agents, its composition is strictly defined (= is a mixture of a branched polymer and some unbranched polymer, and the branching efficiency is insufficient). In some cases, or in the case of a polymer coupled with a polymer having an extremely sharp molecular weight distribution such as obtained by batch polymerization, the gel permeability chromatogram is more than bimodal with one part of the unbranched polymer and one part of the branched polymer. shape or a complicated shape with shoulder beaks.In this case, it is not only difficult to obtain the styrene solution viscosity specified in the present invention, but also
Such polybutadiene rubber cannot be used as a vulcanized rubber with excellent impact resilience and flexibility according to the present invention; The polybutadiene rubber used in the present invention needs to have a high substantial coupling efficiency and a monomodal gel permeability chromatogram.

In addition, the polybutadiene rubber used in the present invention has a weight average molecular weight (W) of 5 to 00,000 as measured by gel permeation chromatography, a book average molecular weight and a number average molecular weight
Molecular weight distribution (Mw /
汀n)But 1. It is necessary that j-9,0. M
If w is less than 50,000, the vulcanized rubber will have insufficient strength, and it will also have a low viscosity and be difficult to handle.On the other hand, if pJw exceeds 500,000, Not only is it difficult to produce the rubber itself, but the processability is also insufficient.

Furthermore, the molecular weight distribution represented by Mw/Mn is 7. It is also necessary for the value to be 0 to 0; if the value is less than 73, the processability as a rubber is insufficient; on the other hand, if it exceeds 0 (-, the rebound and bending resistance are highly Therefore, the polybutadiene rubber defined in the present invention has a Mw of j-!00,000 as measured by gel permeation chromatography, and Mw /Mn
is 1. j ~', t, 0, particularly preferably M
w is 100,000 to 300,000, Mw/Mn is 8 to 2. This is the case when j.

Further, the polybutadiene rubber of the present invention has a Mooney viscosity [ML] of 2 when measured at 100°C using an L rotor.
It needs to be between 0 and 90.

When the ML exceeds 90, it is difficult to handle it as a rubber in terms of processability and the like. On the other hand, if the ML is less than 20, the desired high impact resilience cannot be obtained even by the method of the present invention. The preferred ML is 2! 〜♂0.

Furthermore, the polybutadiene rubber used in the present invention is at 25°C! The solution viscosity (SV) of the wt% styrene solution is 2
It needs to be 0 to 100 centivoise. 20
If the solution viscosity is less than 7 centipoise, the rebound properties will be insufficient even by the method of the present invention, and if Sv exceeds 100 centipoise, the effect on bending resistance will be insufficient. A particularly preferred solution viscosity is between 30 and 70 centipoise.

Furthermore, this polybutadiene rubber! The ratio of the respective logarithms of the heavy ring styrene solution viscosity and Mooney viscosity is θ, ♂2 to 8/which range is 0. If the rubber is smaller than ♂, even if the rubber has a high Mooney viscosity, the solution viscosity is still too low and the rebound properties are insufficient even in the method of the present invention (2). If it is too large, the viscosity of the solution is too high, resulting in poor bending resistance.

Preferably, the ratio between Sv and kltML is Q,9/
~1.09 (- in some cases).

Polybutadiene having a specified structure as described above can be easily produced by, for example, a continuous polymerization method (2). and feed an inert solvent,
Immediately after completing the polymerization step consisting of carrying out the polymerization reaction in the ellipse, a coupling step is carried out in another reaction tank or the like. By going through such a manufacturing process, the productivity of the polybutadiene rubber is dramatically improved compared to the batch polymerization method, and it is also very advantageous in terms of its industrial utility value.

The present invention comprises a raw rubber containing at least 30% by weight, preferably 30% by weight, of the branched polybutadiene described above. If the proportion of branched polybutadiene is less than this, the composition or rubber of the present invention will not sufficiently exhibit its characteristics, that is, excellent impact resilience and bending resistance. Other components constituting the raw rubber are natural rubber or synthetic rubber, and preferred synthetic rubbers include polybutadiene rubber, styrene-butadiene copolymer rubber, synthetic polyisoprene rubber, ethyne-propylene copolymer rubber, and isoprene-isobutylene. Examples include copolymer rubber, chloroprene rubber, butadiene-acrylonitrile copolymer rubber, and particularly preferred other raw rubber components include natural rubber, polybutadiene rubber, and styrene-acrylonitrile copolymer rubber.
It is a butadiene copolymer rubber.

1 and 2 constituting the composition that is the basis of the vulcanized rubber of the present invention
The component is a filler, and carbon black is a typical example, and various products with different particle sizes or struts are used in various manufacturing methods.
Carbon blacks such as 18AF, HAI', and FgF are preferably used for applications mainly in tires. The amount of carbon black to be added is determined by taking into consideration the amount of process oil used at the same time, and is preferably /θ to /jθ weight μ parts, preferably 2θ to 1
00 heavy weight portion is used. The type and amount of carbon black to be added are appropriately adjusted depending on the intended use of the rubber composition, and two or more types may be used in combination.Other fillers include inorganic fillers such as silica and activated carbonate Reinforcing agents, styrene resins, phenol-formaldehyde resins, etc. are used, and these inorganic or organic fillers*IJ] are used in amounts of 20 parts by weight per 00 parts by weight of raw material bottles.
~50 parts by weight, preferably 3θ~100 parts by weight are used.

Further, the third component of the present invention is sulfur and a vulcanization accelerator, and sulfur is used alone or in combination with sulfur chloride, morpholine disulfide, and alkylphenol disulfide.

The amount used is generally 0 to 2 parts of raw rubber 10θ
．． 7 to 70 parts by weight, preferably θ. 2~! Blood eyes are used.

In addition, there are a wide variety of vulcanization accelerators, and these are 0.07 to 2 parts per 100 parts of raw rubber.
It is used in an amount of 5 parts by weight, and can be used in two or more batches. Typical vulcanization accelerators include IT, guanidine,
aldehyde-amine and aldehyde-ammonia systems,
Examples include thiazole series, imidapurine series, thiourea series, chiclam series, dithiocerbamate series, xanthate series, and mixing accelerators.

In addition, vulcanization aids include metal oxides such as lead oxide, fatty acid compounds such as stearic acid, and amines.
These are generally (20.7 to 20.7 to
70 parts by weight are used.

The amounts of sulfur and vulcanization accelerator used in the present invention vary depending on the relationship between ML and Sv of the branched polybutadiene rubber used. That is, it is necessary to use sulfur and a vulcanization accelerator in an amount twice as much (heavy part) as the linear polybutadiene rubber in which the relationship of pupil SV/pupil ML is 3θ to 1.3.

Outside this range, it will not be possible to obtain a vulcanized rubber with physical properties (200%) that is mainly composed of branched polybutadiene rubber having the specified structure as the object of the present invention.

In other words, when sulfur and vulcanization accelerator are too small (=
The strength and modulus of rubber are insufficient, and the rebound properties are also poor; conversely, if there is too much, not only will the hardness increase more than necessary for the rubber and the flexural growth resistance will decrease, but the rebound properties will also deteriorate at high and low temperatures. There is little change and it is not favorable.

The above rubber composition (additional ingredients include softeners, fillers, anti-scorch agents, anti-aging agents or antioxidants, tackifiers, coloring agents, lubricants, lubricants, foaming agents) , and other compounding agents, which are appropriately selected and used as necessary.

The rubber composition of the present invention is kneaded using a rubber mixing roll, an internal mixer, an extruder, etc., then molded, and then heated at a temperature of 73θ to 73θθ℃ in a conventional manner. Sulfurized.

The vulcanized rubber obtained by vulcanizing the above-mentioned composition of the present invention is 70%
The impact resilience (JIS) measured at 2J°C and 2J°C satisfies the following formula.

2. Impact resilience (measured at 70°C) - Impact resilience (measured at 25°C) (10) For rubbers outside the above range, branched polybutadiene rubber specified by the present invention was used as raw material rubber for vulcanized rubber. This is meaningless and is not the purpose of this invention.

A vulcanized rubber having the above characteristics can be obtained by suitably vulcanizing a raw material rubber and a composition that satisfy the constituent requirements of the present invention.

The vulcanized rubber of the present invention is suitable for tire treads, and is particularly used for low fuel consumption tires, all-season tires, cap treads, undertreads of high-performance tires, etc.; It can also be used in tire parts such as side falls, carcass, cushion rubber, anti-vibration rubber, industrial products, etc.

〔Example〕

Examples are shown below, but these are intended to more specifically illustrate the present invention, and are not intended to limit the scope of the present invention.

EXAMPLE/The specified polybutadiene of the present invention was synthesized by carrying out the following sequential combinations.

In a polymerization tank with an internal volume of 101 and equipped with a stirring blade and a jacket, a mixed solution of 7.3-butadiene-〇-hexane with a concentration /j% of 2001r415-f and <t o, r pp
m concentration of a-butyl lithium-〇-hechitin mixture! 0 mm was continuously pump-fed. Rotation speed 720 rpm/
The polymer solution was mixed and stirred at a polymerization temperature of 100° C. for 10 minutes, and the overflowing polymer solution was fed into a coupling reaction tank having the same shape and equipment as the above-mentioned polymerization tank. The fed polymer solution and the n-hexane solution of 5iC64 were pump-fed at a flow rate of 5θψ minutes to n-butyl lithium so that the amount was 0.
IJj was set to ♂θ°C and mixed with stirring. Di-tert-butyl-gu-methylphenol was added as a stabilizer to the polymer obtained by overflowing from the coupling reaction tank, and the solvent was distilled off under heating to obtain a polymer. The physical property values of the obtained polymer are shown in the table below. The obtained Polymer A was mixed in a roll with the formulation shown in Attachment 3A and the amounts of sulfur and vulcanizing agent shown in Table 2, and press vulcanized to obtain a vulcanized rubber. Table 2 shows the shocking properties of this product.

The measurements were performed using the method shown below.

(1) Hardness, tensile strength: According to JIS-Otsu 30/(=Compliant.

(2) Resilience: Rupke method according to JIS-≦307. However, impact resilience at 70°C was measured by preheating the sample in a 70°C oven for 7 hours and then quickly removing it.

(3) Gutdrich heat generation: Tested using a Gutdrich flexmeter under the conditions of load 4J' bond, displacement 0.18 inches, start SO ℃, rotation speed/♂00 pm, and increase after 20 minutes. It represents the temperature difference.

(4) Wet skid resistance: Using Stanley London's Portable Skid Tester, Safety Walk l? AST using MM)
It was measured according to the method of M-B-♂0♂-7. Comparative example 3
It is expressed as an index with the measured value as 100.

(5) Abrasion resistance: Expressed as an index with the measured value of Comparative Example 3 set as 100 using a Pico abrasion tester.

(6) Demanya bendability: Using a Demanya bending tester, three scratches showed 70 arcs (=number of bends until growth).

Comparative Example 1.2 A vulcanized rubber was obtained by using a polymeric compound only for iota and the amount of the vulcanizing agent. The physical properties of this product are shown in Table 2.

Comparative Example 3 Polybutadiene C was experimentally produced by performing the same operation as shown in Example 1 and changing the amount of n-butyllithium and the branching agent (no branching agent was used in C). The physical properties of the obtained polymer are shown in Table 7 (2), and the physical properties of the vulcanized rubber are shown in Table 2 (2).
= Show.

It can be seen from Examples/Comparative Examples/--3 that the vulcanized rubber of the present invention not only has excellent rebound properties but also excellent bending resistance and is suitable for tire applications and other uses.

Examples C, 3 and Comparative Examples q to 7 Natural rubber or synthetic rubber containing polybutadiene and polybutadiene C as main components (emulsion 8BR#/!f
02) to prepare each vulcanized rubber with the raw material rubber binding material and the formulations shown in Table 2. The physical properties of the vulcanized rubber are shown in Table 2 (=.The vulcanized rubber of the present invention has the same properties as when used alone at a blend ratio within the specifications of the present invention (
= It can be seen that this effect is exhibited and an excellent vulcanized rubber is provided.

Examples G, J and Comparative Example ♂~/! Polybutadiene samples B, D, E, and G were produced by the same method as shown in Example (two operations were performed, and the amount of lobethyllithium and the amount of branching agent were varied).The physical properties of these polymers were Table 7 (=shows.

In Comparative Examples /3 and /g, vulcanized rubber was prepared using polybutadiene rubber obtained by the following batch polymerization method.

In a polymerization vessel with an internal volume of 101 mm and equipped with a stirring blade and a jacket, there is a four-layered A4! 1.3-butadiene-n-hexane mixture ♂t and a concentration of 0. /2 mol/l n-butyllithium solution 1. ! ;, feed 7 ml and incubate at 720°C for 30
Polymerization was carried out for minutes. Furthermore, a solution of 5iC44 in n-hexane was added to 1-butyllithium at 0.0%. ♂ Double allowance Q i
The mixture was added and reacted at 100° C. for 30 minutes with stirring. The subsequent treatment was carried out in the same manner as in Example/1 to obtain Polymer F.

Appendix Table B and Table 3 (-
A heated rubber was obtained using the formulation shown and its physical properties were measured. The results are shown in Table 3. It can be seen that when a raw rubber within the scope of the present invention is used and the amounts of iota and vulcanizing agent are also appropriate, the effects of the present invention are manifested and excellent properties are exhibited.

Attached table Human raw material rubber 100M@part aromatic oil *1 10p carbon black
N-330ta0I Stearic acid 2 #Zinc white
33 1 Accelerator CZ*2
1.3 1 ioc
2I*1 Kyodo Ishiura Carbon black N
-330g parts by weight stearic acid
2 parts by weight Accelerator CZ 1. θ parts by weight Ioc 1.2 parts by weight Vulcanization conditions /j θ℃ x 30 minutes (blank below)

Claims (1)

[Scope of Claims] (1) a) gel permeation obtained by polymerizing with a lithium-based catalyst and further using a branching agent in an amount of 0.2 to 1.5 equivalents to the lithium-based catalyst; It has a monomodal molecular weight distribution with a weight average molecular weight measured by chromatography of 50,000 to 500,000 and a ratio of weight average molecular weight to number average molecular weight of 1.5 to 4.0, and b) uses an L rotor. , Mooney viscosity [ML] measured at 100°C is 20-90, c) 5 wt% styrene solution viscosity [SV
] is 20 to 100 centipoise d) The relationship between [ML] and [SV] above satisfies the following formula: 0.82≦(logSV)/(logML)≦1.18
Raw material rubber containing at least 30% by weight of branched polybutadiene rubber, 100 parts by weight (2) Filler, 20 to 150 parts by weight (3) Sulfur and vulcanization accelerator, the relationship (logSV)/(logML) is 1. 30-1
．． Measured at 70°C and 25°C by vulcanizing a composition consisting of the following formula (parts by weight): 1.25 (logML)/(logSV) ±0.2 of the amount used in the linear polybutadiene rubber 35. Vulcanized rubber whose rebound elasticity (JIS) satisfies the following formula. 2% < Resilience (measured at 70°C) - Resilience (25°C) <
10%