JPS62207345A - Rubber composition - Google Patents

Abstract

PURPOSE:To provide a rubber compsn. having excellent resistance to heat and cold, processability and vulcanization characteristics, by blending a specified ethylene/alpha-olefin copolymer rubber with an inorg. filler and naphthenic or paraffinic oil. CONSTITUTION:An ethylene/alpha-olefin copolymer rubber (A) composed of 30-60wt% ethylene and a 3-8 C olefin, which has a ratio of weight-average MW to number-average MW of not lower than 4, an intrinsic viscosity of 1.6-4.0dl/g as measured in xylene at 70 deg.C, a green strength index of not lower than 0.8, a breaking strength GM of GM>=1.3 G100 and elongation at break of 900% or about and wherein a difference between the ethylene content of its high-molecular component and the mean ethylene content is 10-30, is blended with an inorg. filler (B) and naphthenic or paraffinic oil (C) in a ratio of 1<=(B+C)/A<=2 and 1.5<=B/C<=4 to obtain a compsn. which has a roll processing index of not lower than 3.0 and gives a vulcanized product having a ratio of tensile strength at break to Mooney viscosity (121 deg.C) of unvalcanized rubber blend of 1.5-2.5.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to ethylene/α-olefin copolymer rubber, and furthermore, to ethylene which has a wide molecular weight distribution, has a uniquely high raw rubber green strength, and has good processability. - It relates to a vulcanized rubber composition comprising an α-olefin copolymer rubber, a filler, and a plasticizer.

Ethylene/α-olefin copolymer rubber has excellent heat resistance, cold resistance, and weather resistance, and is used in automobile parts, industrial products, electrical equipment parts, etc.1 For example, socket covers, heat-resistant hoses,
Electric wire, capacitor cap.

Can be used for heat-resistant belts, vibration-proof rubber, etc.

<Conventional technology> General ethylene/propylene copolymer com.

Ethylene/α-olefin or , ethylene/α-olefin/polyene copolymer rubber has excellent weather resistance, heat resistance, ozone resistance, etc., and is known to be used for building materials, electric wire materials, automobile parts, etc. Among these uses, it is known that ethylene/α-olefin copolymer rubber that does not contain polyene is preferable for uses that particularly require heat resistance.

Also, for applications that require heat resistance and cold resistance.

Ethylene with an ethylene content of 60 wt% in the copolymer.
It is well known that α-olefin copolymer rubber is preferable.

In addition, the ethylene/α-olefin copolymer rubber used in such applications (required properties include excellent processability and, at the same time, excellent vulcanizable properties).

However, with the technology shown in the conventional literature, ethylene, which has good processability and vulcanizable properties, and has excellent heat resistance and cold resistance,
There was no known means for obtaining an α-olefin copolymer rubber composition.

<Problems to be Solved by the Invention> An object of the present invention is to solve these problems and provide a material with excellent heat resistance and cold resistance, as well as excellent processability and vulcanizable properties. An object of the present invention is to provide a rubber composition comprising ethylene/α-olefin copolymer rubber.

Means to solve problems〉 The present inventors found that processability and vulcanizable properties were good.

As a result of extensive research into ethylene/α-olefin copolymer rubber that has excellent heat and cold resistance, we have discovered an ethylene-substituted olefin copolymer rubber composition that achieves this objective.

This rubber composition is characterized by an ethylene content of 60 to 3
The Q value of one molecular weight distribution is 4 or more at 0 wt%.

and an ethylene/α-olefin copolymer rubber in which the ethylene content of the high molecular weight portion is higher than the average ethylene content of the copolymer, resulting in extremely high green strength of the raw rubber, and a specific proportion of inorganic filler and oil. It consists of plasticizers such as

In the conventional ethylene/α-olefin copolymer rubber composition, the green strength of the raw rubber decreases as the ethylene content decreases, and the processability worsens. Things are unique.

In other words, one aspect of the present invention is.

(2) Consisting of ethylene and α-olefin having 3 to 80 carbon atoms, with an ethylene content (wt%) of ω to 30w
t%, Q value (weight average molecular weight/number average molecular weight) is 4 or more, intrinsic viscosity measured at 70°C in xylene is 1.6 to 4.0 dllf, and green strength index G measured at 23°C is Ga4.8 ．． Breaking strength GM is GM≧1,3G1
OA, ethylene/α-olefin copolymer rubber, and B) an inorganic filler and naphthenic or paraffinic oil in such a manner that I≦(inorganic filler child oil)/copolymer rubber≦2,5.
And the ratio is 1.5≦inorganic filler/oil≦4.

Ω roll workability index is 3.0 or more and 01.5≦-
The present invention relates to a rubber composition with excellent processability and physical properties, characterized in that / Comp'd M L≦2.5°.

In the (g) ethylene/α-olefin copolymer rubber of the present invention, the ethylene content of the high molecular weight component is E.

wt%, when the average ethylene content is expressed as EAwt%.

It is preferable that the relationships are IO≦E and −EA≦30. Further, it is necessary that the elongation at break E measured at 23° C. is 900% or more.

(g) The α-olefin having 3 to 8 carbon atoms, which is one component of the copolymer rubber of the present invention, includes propylene, 1-7
``Tene, I-pentene, l-hexene.

Examples include 4-methyl-1-pentene, l-octyne, mixtures thereof, propylene, l-
Butene is particularly preferred. (g) The ratio of ethylene to α-olefin in the copolymer rubber is selected within the range of 60 to 30 wt% as the ethylene content. If the ethylene content is 60wt% or more.

It is not preferable because a decrease in cold resistance is observed. Moreover, even if the ethylene content is 30 wt% or less, a decrease in cold resistance is observed.

The ratio of ethylene to α-olefin varies depending on the type of α-olefin, but when the α-olefin is propylene, the ethylene content is in the range of 60 to 30 wt%, preferably 60 to 40 wt%.

The ethylene content can be determined by measuring the C-NMR spectrum or absorbance using an infrared spectrophotometer.

The molecular weight of the copolymer rubber (2) of the present invention is 7 in xylene.
Intrinsic viscosity measured by 3-point method at 0°C: 1.6 to 4
．． A range of 0 dl/9 is preferred. If it is less than 1.6 dt/S', the vulcanized physical properties will be poor, and if it is more than 4.0 di/S', kneading and extrusion processing will become difficult, which is not preferable.

(G) Molecular weight distribution of copolymer rubber is an important factor that serves as an indicator of processability.1 In the present invention, the Q value (weight average molecular weight/number average molecular weight) is 4 or more, preferably 6 or more. is preferred. If the Q value is less than 4, good workability cannot be obtained. The Q value was measured as follows according to "Gel Permini-Silanne Chromatography" written by Takeuchi and published by Maruzen.

GPC: Waters 150 Type C column: Showa Denko 5hodex 80MA Sample amount:
300μt (polymer concentration 0.2wt%) flow rate: 1
rrt/min Temperature: 135°C Solvent: Trichlorobenzene The calibration curve was prepared by a conventional method using standard polystyrene manufactured by Toyo Soda ■. Further, data processing was performed using a data processor CP-8 model ■ manufactured by Toyo Soda ■.

(g) The green strength and elongation at break of the copolymer rubber of the present invention are also important indicators of processability and vulcanizable properties, and the green strength index G described below is G≧0.8 and GM≧1.3. G
+ao and elongation at break E of 900% or more.

More preferably G≧0.9. It is preferable that GM≧1.5 G+oo.

Here, the green intensity index G is G = Gy country/G + o
.

G9+10 is the stress at 900% elongation, Go
o is the stress at 100% elongation. Furthermore, GII indicates breaking strength. The tensile test was conducted using a T-type strograph manufactured by Toyo Seiki under the following conditions.

Test piece: JISa dumbbell thickness 2fi tensile speed: 50
0 parrot/min Measurement temperature: 23°C Green intensity index G <, 0.8. Also, breaking strength GI
I is G-<1.3 G+oo, elongation at break E is 90
If it is less than 0%, workability, especially roll workability, is poor.

In addition, (g) the copolymer rubber of the present invention has an ethylene content of the high molecular weight component Eywt% and an average ethylene content EAwt%.
The relationship of % preferably satisfies the following formula.

That is, 10≦E, -E, ≦30. More preferably, the range is 15≦E and -EA≦30.

E, -EA (if it is to, the green strength is low and the processability is poor; if it is 30, the ethylene content in the high molecular weight part is high, and the cold resistance is reduced).

Here, the high molecular weight component, the ethylene content E of the high molecular weight component,
, the average ethylene content EA is defined as follows.

(2) Separate the copolymer rubber into 16 to 21 fractions by column fractionation. Measure the ethylene content and intrinsic viscosity of each fractionated flax.

The separation conditions are as follows.

(i) Copolymer rubber 30f is coated on 2650 y of sea sand of 60 to 80 ml.

(ii) Elution is performed at 80°C using a mixed solvent of toluene/isopropyl alcohol as the elution solvent.

After taking an eluting solution for 4 hours at 8 cc/min as a first flux, the composition of toluene/isopropyl alcohol was changed and the primary flux was eluted. The composition of toluene/isopropyl alcohol starts from 50150 (vol. 1%) and gradually increases the toluene ratio to 51/49.52/48.53/47, and if necessary, the final fraction is eluted with 100% toluene.

(ii+) The eluate was concentrated and then precipitated in methanol.

The precipitate is dried under vacuum and its weight is measured.

(2) Create a cumulative curve in order of molecular weight of the fractionated products, and divide 24% into 20 wt% on the high molecular weight side and the remaining 80 wt%.

Measure the ethylene content of each. The component on the high molecular weight side is H1, the ethylene content is E or wt%, and the average ethylene content is EAwt%. From this, E, EA can be found.

In the present invention, as the inorganic filler (IB), carbon black or a white filler such as silica, talc, or clay is used, and carbon black is particularly preferred.

Further, (2) as the oil, paraffinic or naphthenic oils are preferred.

In the present invention, ■ the amount of inorganic filler and oil is
l≦(Inorganic filler child oil)/Copolymer rubber≦2.5.
It is important to blend preferably l≦(inorganic filler child oil)/copolymer rubber≦2 and 1.5≦inorganic filler/oil≦4.

The blending ratio of (inorganic filler + oil)/copolymer.

If it is less than 1 or more than 2.5, the processability and physical properties of the composition will not be improved. Furthermore, if the blending ratio of inorganic filler/oil is less than 1.5, the processability is good, but the physical properties deteriorate due to the increased amount of oil added. Also, if the blending ratio of inorganic filler/oil exceeds 4, the amount of oil added will decrease.

Workability deteriorates.

In the present invention, the zero roll processability index indicates the roll processability of a rubber compound and is determined by the following method.

Roll = 6 inch roll Roll temperature: 50°C Roll gap A (w) The roll windability of the compound is observed. The value of A is set to 0.5°1.
0. The A value at which the blend causes bagging is taken as the roll processability index.

The formulation is as follows.

■Mixture■Mixing Mix compound A with BR Banbury, 12 bottles x 5 minutes, add all at once, start at 70℃. Thereafter, Formulation B was added using an 8-inch roll to obtain a formulation. Roll temperature 50℃
.

The larger the roll processability index is, the better the roll processability is, but for practical purposes, it is required to be 3.0 or more.

In the present invention, 0) T-/ComFdML refers to the ratio of the tensile breaking strength of the vulcanized product 1) and the Mooney viscosity (CompdML) of the unvulcanized rubber compound, and is a measure of the balance between physical properties and processability. Yes.

It is necessary that 1.5≦T, /ComIlydM L≦2,5. In addition, Compd M L is 12
Measured at 1°C.

If T/Com9d M L < 15, the processability is good but the vulcanizable properties are poor, and Ts/C:a
On the other hand, if npdM L )2.5, the physical properties of the vulcanizate are good, but processability deteriorates, which is not preferable.

Next, an example of the method for producing (g) copolymer rubber according to the present invention will be described.

As the catalyst for producing the copolymer of the present invention, a so-called Ziegler-Natsuta catalyst is used, which requires a combination of an organoaluminum compound and a trivalent to pentavalent vanadium compound soluble in a hydrocarbon solvent. As the above aluminum compound,
Alkyl aluminum sesquichloride, trialkyl aluminum.

';7 Le'F/real aluminum monochloride,
Alternatively, a mixture thereof is preferable, and the vanadium compound is vanadium oxytrichloride, vanadium tetrachloride, or V○(OR) nX5-n (o (n≦3
Preferably, R is a vanadium compound represented by a linear bibranched or cyclic hydrocarbon having 1 to 10 carbon atoms.

At this time, the ratio of the organic aluminum compound to the vanadium compound is preferably in the range of 6.0 to 2.0. Below 2, a large amount of gel is formed or a significant decrease in activity is observed.
Moreover, if it is 6.0 or more, the Q value becomes small and the copolymer which is the object of the present application cannot be obtained.

9 In producing the copolymer according to the present invention,
The copolymer may be produced in such a way that a portion of the high molecular weight component containing an ethylene content higher than the average ethylene content of the copolymer is produced. This is more than 2 tanks.

Alternatively, in a two or more stage polymerization method, this can be achieved by controlling the composition and amount of the copolymer produced in the first and second tanks, or the first and second stages, etc. . By this method, ethylene α according to the present invention can be obtained.
- An olefin co-ffi polymer rubber is obtained.

The composition of the copolymer rubber can be adjusted by varying the ratio of ethylene to alpha-olefin in one reactor. Also, what is the molecular weight of the copolymer rubber?

The concentration of hydrogen used for molecular weight control is controlled by the polymerization temperature, and the concentration of ethylene and α-olefin in the reactor. The polymerization temperature is 35°C to 70°C, or even 4°C.
A range of 0°C to 70°C is preferred.

The (B) inorganic filler and naphthenic or paraffinic oil can be blended into the copolymer rubber (g) obtained in this way by using a conventional Pan Bali mixer or a mixing method using rolls, etc. can.

Further, as a vulcanization method, a vulcanized product can be obtained by employing a conventional press vulcanization method or continuous vulcanization method.

If the rubber composition according to the present invention is used, in addition to the characteristics of good processability and excellent cold resistance and heat resistance, it can be vulcanized with peroxide or the like.

A high-strength vulcanizate is obtained. This vulcanizate is used for automotive parts such as socket covers and hoses, electric wires, capacitor caps, heat-resistant belts, and vibration-proof rubber.

<Examples> The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

Example 1゜ In a lO4 SUS autoclave equipped with a stirrer.

7Kf of hexane, 0 each of ethylene and propylene per hour
．． It was fed at a rate of 33Kf and 1.65Kf.

Further, hydrogen was fed at a rate of 0.036 mol%. Further, ethylaluminum sesquichloride and vanadyl trichloride were fed as catalyst components at a rate of 2.28 and 0.579 per hour, respectively, and polymerization was carried out at 46°C.

After reaching a steady state, the polymerization was continued for 10 hours, and then ethylene and propylene were added at 0.62 V4 and H1, respectively.
．． Ethylaluminum sesquichloride and vanadyl trichloride were fed at a rate of 0.682 and O, I7f per hour to the rate of 61 Kf, and the bipolymerization was further carried out at a rate of 4
It lasted for an hour. The copolymer solution was continuously extracted, demonomerized, washed, and then charged into a lFF/drum.

After the polymerization is complete, the copolymer solution that has entered the IFF/ is steam stripped to separate the polymer.
Dry.

Thus, ethylene content +1-, EA=52wt%, E
, = 70 wt%, intrinsic viscosity 2.39 di/f,
An ethylene/propylene copolymer with a Q value of 8.6 was obtained. When the green strength of this copolymer was measured, G=
1.8. G.

= 2.6 G+oo, elongation at break was 940%.

Furthermore, when the roll processability of this copolymer blend was evaluated, so-called bagging did not occur.

In addition, evaluation of roll processability and preparation of vulcanizate.

The following method was used. The same applies to the following Examples and Comparative Examples.

■Mixing ■Kneading Mix compound A with BR Banbury, add 12 bowls x 5 minutes, all at once, and start at 70℃. Thereafter, Formulation B was added using an 8-inch roll to obtain a formulation. d-ru temperature 50℃
.

■ Evaluation of roll workability (roll workability index) Roll:
6-inch roll Roll temperature Button °C Roll gap A+m++ (A=0.5.1.0.1.
5. --) was used to evaluate the degree of wrapping.

■ Vulcanization conditions: Press vulcanization was performed at 160°C for 20 minutes.

Example 2゜ Example 1. Polymerization and post-treatment operations were performed in the same manner as above.

However, the first polymerization temperature was 40°C. In this way, a copolymer with an ethylene content of EA=50 wt%, &+=70 wtX, an intrinsic viscosity of 2.76 cit/y, and a Q value of 6.7 was obtained. When the green strength of this copolymer was measured, it was found that G=0.9°GM=1.8×G+aa,
The elongation at break was 1500% or more. (At this time, GM was 15
It is represented by the strength at 00% elongation. ) Also, the roll processability of the blend of this copolymer was evaluated, and it was found to have good roll processability without causing so-called bagging.

These results are shown in Table 1 together with the vulcanization physical properties.

Comparative example 1゜Example 1. Using the same reactor, 4.1.65 Kf of hexane, ethylene, and propylene were each added at 0.33 and 1.65 Kf per hour.
Feed at a rate of Further, hydrogen was fed at a rate of 0.015 mol%. Further, as catalyst components, ethylaluminum sesquichloride and vanadyl trichloride were fed at a rate of 2.289 and 0.57 y per hour, respectively, and polymerization was carried out at 46°C.

After reaching a steady state, the polymerization was continued for 14 hours.

The copolymer solution was continuously withdrawn, demonomerized, washed, and then charged into the drum of IFF+'. After the polymerization is completed, the copolymer solution in the IR drum is steam stripped to separate and dry the polymer.

Thus, the ethylene content is: EA = 51 wt%, E, =
60wt%, intrinsic viscosity 2.38dt/f, Q value 4
．． A copolymer of No. 6 was obtained. However, when the green strength of this copolymer was measured, it was found that G = 0.4,
GM = 0.3 G+o.

(GM adopted stress of 1500% elongation), E, >
It was 1500%.

Further, when the roll processability of a blend of this copolymer was evaluated, so-called bagging occurred and the roll processability was poor.

These results are shown in Table 1 together with the vulcanization physical properties.

Comparative example 2゜ Comparative example 1. Polymerization and post-treatment were carried out in the same manner as above.

However, the polymerization temperature was 40° C., and hydrogen was fed at 0.01 mol %. Thus, the ethylene content is EA=54wt%
.

E, = 62wt%, intrinsic viscosity 2.93 dt/51
+' A copolymer with a Q value of 3.4 was obtained. When the green strength of this copolymer was measured, the elongation at break was 430%, and G could not be measured. Also GM = 0.35G
, Go.

The roll processability of this copolymer formulation was evaluated, but resulted in bagging and holes in the sheet.

Roll processability was poor.

These results are shown in Table 1.

Comparative example 3゜ Comparative example 1. Polymerization and post-treatment were carried out in the same manner as above.

However, the polymerization temperature is 50℃, hydrogen is fed at 0.07 mol%, and ethylene and propylene are each fed at 0.46 K/hour.
f and 1.41 KIi. Further 5-
Ethylidene-2-norbornene at 0.037 Ky/hour
(') Feed in percentage. Further, ethylaluminum sesquichloride and vanadium oxytrichloride were fed as catalysts at a rate of 2.52 and 0.52 per hour, respectively.

What is the ethylene content of the copolymer thus obtained?

F=68 wt%, E++=71 wt%, iodine value was 3, intrinsic viscosity was 1.86 delf, and Q value was 2.7. The green strength of this copolymer was evaluated.

G = 4.4, GM = 8. OGw, E-=
It was 1280%.

Further, when the roll processability of the blend of this copolymer was evaluated, the roll processability was found to be good.

However, when we measured the physical properties of the vulcanizate, we found that the low-temperature properties (
Low-temperature compression (small permanent set) was poor, and heat aging resistance was also poor.

These results are shown in Table 1.

<Effects of the Invention> As explained above, according to the present invention, heat resistance and cold resistance, as well as processability and vulcanized physical properties, were superior to those of the prior art. A rubber composition made of ethylene/α-olefin copolymer rubber can be provided.

Claims (4)

[Claims] (1) (A) Consisting of ethylene and α-olefin having 3 to 8 carbon atoms, ethylene content 60 to 30 wt%, Q value (weight average molecular weight/number average molecular weight) 4 or more, measured in xylene at 70 °C The intrinsic viscosity is 1.6 to 4.0 dl/g,
and the green strength index G is G≧0.8, and the breaking strength G_M is G_M≧1.3G_1
_0_0 ethylene/α-olefin copolymer rubber, and (B) inorganic filler and naphthenic or paraffin oil, 1≦(inorganic filler + oil)/copolymer rubber≦2, and 1.5≦inorganic It consists of blending filler/oil in a ratio of 4, (C) a roll processability index of 3.0 or more, and (D) 1.
A rubber composition characterized in that 5≦T_B/Comp'dML≦2.5. (2) The rubber composition according to claim 1, wherein the α-olefin (A) is propylene and the ethylene content is 60 to 40 wt%. (3) The rubber composition according to claim 1, wherein the α-olefin (A) is 1-butene. (4) (A) The green strength index G of the copolymer measured at 23°C is G≧0.9, and G_M≧1.5G_1_0
The rubber composition according to claim 1, which is _0.