JP2001123016A - Rubber composition and its preparation process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition which shows an improved processibility without deteriorating wear resistance, low heat build-up (rolling resistance property) nor wet skid performance, and a preparation process thereof. SOLUTION: A rubber composition contains, against a natural rubber and/or a synthetic diene rubber, a white filler as a filler, from 1 to 20 wt.% silane- coupling agent having a structure of the formula: Y3-Si-CnH2nA against the white filler and from 4 to 20 wt.% polyoxyalkylene glycol compound having a structure of the formula: R1O(R2O)nH against the white filler.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a low heat generating property (rolling resistance characteristic) without lowering workability and wear resistance.
The present invention relates to a rubber composition having excellent wet skid performance and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, the characteristics required for automobile tires are various, such as low fuel consumption, driving stability, wear resistance, and riding comfort. Various improvements have been made to improve these performances. Among these performances, the grip performance and the rolling resistance characteristic of the tire are all performances related to hysteresis loss of rubber. Generally, when the hysteresis loss is increased, the grip force is increased and the braking performance is improved, but the rolling resistance is increased and the fuel efficiency is increased. Thus, the grip performance and rolling resistance characteristics
Because of the conflicting relationship, various rubber compositions for tires have been proposed to simultaneously satisfy both characteristics. For example, in a rubber composition for a tire, particularly since a polymer and carbon black greatly affect both properties,
When a styrene-butadiene copolymer is used as the polymer, the content of bound styrene, butadiene moiety 1,
The two-bond content is appropriately selected to improve both the rolling resistance characteristics and the grip performance.

In recent years, a method of using a white filler such as silica and a silane coupling agent as a filler for reducing heat generation has been known. The reason that the silane coupling agent is used together is that silica particles tend to agglomerate due to hydrogen bonding of silanol groups, which are surface functional groups, and the silane coupling agent bonds with these silanol groups to aggregate silica particles. This is because it is said that it is possible to improve the workability. On the other hand, in terms of performance, it is considered that the rolling resistance is reduced and the abrasion is improved by chemically bonding the silica and the polymer to the silane coupling agent. However, in order to achieve these objects, it is necessary to knead the silica and the silane coupling agent and allow them to react sufficiently at a high temperature during processing. However, the functional groups that react with the rubber in the silane coupling agent partially react with the rubber before reaching the vulcanization step due to the temperature applied during processing such as kneading, so rubber burning called gelation occurs Phenomenon occurs. Conversely, if the kneading is carried out at a low temperature, the reaction between the silica and the silane coupling agent becomes insufficient, causing a problem that high performance cannot be obtained.

[0004]

SUMMARY OF THE INVENTION The present invention relates to
It is an object of the present invention to provide a rubber composition and a method for producing the same, which can significantly improve processability without lowering heat generation properties (rolling resistance properties) and wet skid performance.

[0005]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and have found that a white filler, a silane coupling agent and a specific polyoxyalkylene glycol compound are added to rubber components such as natural rubber. The present inventors have found that a rubber composition which can significantly improve processability without deteriorating abrasion resistance, rolling resistance characteristics, and wet skid performance can be obtained by blending the rubber composition, thereby completing the present invention.

That is, the present invention contains a white filler as a filler for natural rubber and / or diene-based synthetic rubber, and has the following general formula (I): Y ₃ —Si—C _n H _2n A (I (In the formula (I), Y is an alkyl group having 1 to 4 carbon atoms, an alkoxyl group or a chlorine atom, and three Y's may be the same or different; n represents an integer of 1 to 6; Is -S _m C _n
H _2n Si-Y ₃ group, a nitroso group, a mercapto group, an amino group, an epoxy group, a vinyl group, a chlorine atom, imido group and -S _m Z group (wherein, m is an integer from 1 to 6, n and Y is the same as above, and Z is the following chemical formula
(II), a group represented by the chemical formula (III) or the chemical formula (IV)); % Included

[0007]

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[0008]

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[0009]

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Further, the following general formula (V): R ¹ O (R ² O) _n H (V) (In the formula (V), R ¹ is hydrogen or an alkyl group having 1 to 6 carbon atoms, and R ² is A methylene group, an ethylene group, a propylene group, and a tetramethylene group, all of which may be the same or different, n is an integer of 1 to 20, and the molecular weight of the polyoxyalkylene glycol compound is 200 to 1000 The polyoxyalkylene glycol compound represented by the formula:
2. The rubber according to claim 1, wherein the rubber composition containing at least 1% by weight (Claim 1), a white filler, a silane coupling agent and a polyoxyalkylene glycol compound are mixed at a kneading rubber discharge temperature of 150 ° C. or lower. The present invention relates to a method for producing a composition (claim 2).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The rubber component used in the present invention is a natural rubber (NR) and / or a diene-based synthetic rubber.
Examples of the diene-based synthetic rubber include styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), and ethylene-propylene-diene rubber (EPD).
M), chloroprene rubber (CR), acrylonitrile-
Butadiene rubber (NBR) and the like may be mentioned, and one or more kinds may be contained in the rubber component used in the present invention.

The white filler used in the rubber composition of the present invention includes silica, clay, alumina, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium oxide, titanium oxide and the like. . These can be used alone or in combination of two or more. Particularly preferred white fillers are silica, clay, aluminum hydroxide and alumina in terms of reinforcing properties.

When silica is used, the silica preferably has a nitrogen adsorption specific surface area (N ₂ SA) of 50 to 300 m ² / g. Nitrogen adsorption specific surface area of silica (N ₂ S
When A) is less than 50 m ² / g, the dispersibility improving effect and the reinforcing effect are reduced, and when it exceeds 300 m ² / g, the dispersibility is poor and the heat generation tends to increase.

The amount of the white filler contained in the rubber composition of the present invention is preferably 5 to 100 parts by weight, more preferably 10 to 95 parts by weight, based on 100 parts by weight of the rubber component used in the present invention. Parts by weight, more preferably 20 to 90 parts by weight. If the amount of the white filler is less than 5 parts by weight,
If the reinforcing effect is small, and if it exceeds 100 parts by weight, workability is undesirably reduced. From the viewpoint of low heat generation and workability, the blending amount of the white filler is most preferably 20 to 90 parts by weight.

When a white filler is used, a coupling agent is used in order to strengthen the bond between the filler and the rubber component and improve abrasion resistance. The coupling agent used in the rubber composition of the present invention is a silane coupling agent represented by the following general formula (I).

Y ₃ —Si—C _n H _2n A (I) In the formula (I), Y is an alkyl group having 1 to 4 carbon atoms;
An alkoxyl group or a chlorine atom, three Y's may be the same or different, n represents an integer of 1 to 6, and A represents-
_{S m C n H 2n Si-} Y 3 group, a nitroso group, a mercapto group,
Amino group, an epoxy group, a vinyl group, a chlorine atom, imido group and -S _m Z group (wherein, m is an integer from 1 to 6,
n and Y are the same as described above, and Z is a group selected from the group consisting of the following chemical formulas (II), (III) and (IV).

[0018]

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[0019]

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[0020]

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Examples of such a silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, and bis (3-trimethoxysilylpropyl) tetrasulfide. , Bis (2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane,
3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3- Trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, Trimethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3
-Triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide and the like. Examples of three non-identical Ys include bis (3-diethoxymethylsilylpropyl) tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, 3-nitropropyldimethoxymethylsilane, 3-chloropropyldimethoxymethylsilane, Dimethoxymethylsilylpropyl-N, N
-Dimethylthiocarbamoyl tetrasulfide, dimethoxymethylsilylpropyl benzothiazole tetrasulfide and the like. Bis (3-triethoxysilylpropyl) tetrasulfide or the like is preferable from the viewpoint of achieving both the effect of adding the coupling agent and the cost.

The amount of the silane coupling agent is preferably 1 to 20% by weight based on the weight of the white filler. If the amount of the silane coupling agent is less than 1% by weight, the effect of adding the silane coupling agent is not sufficient,
If the amount exceeds 0% by weight, the coupling effect cannot be obtained despite the increase in cost, and the reinforcing property and wear resistance are undesirably reduced. From the viewpoint of the dispersing effect and the coupling effect, the blending amount of the silane coupling agent is more preferably 2 to 15% by weight.

The polyoxyalkylene glycol compound used in the present invention is a polyoxyalkylene glycol compound represented by the following general formula (V).

R ¹ O (R ² O) _n H (V) In the formula (V), R ¹ is hydrogen or an alkyl group having 1 to 6 carbon atoms, R ² is a methylene group, an ethylene group, A propylene group and a tetramethylene group, all of which may be the same or different, and n is an integer of 1 or more and 20 or less.

The molecular weight of the polyoxyalkylene glycol compound represented by the general formula (V) is 200 to 1
000, preferably 200-800. Even if the molecular weight is smaller than 200 or larger than 1000, it does not result from the dispersibility of the white filler and does not improve the processability.

In particular, from the viewpoint of the dispersion effect of the white filler, R
¹ is preferably a hydrogen or methyl group, while R ² is preferably a methylene group or an ethylene group.

The amount of the polyoxyalkylene glycol compound contained in the rubber composition of the present invention is preferably 4 to 20% by weight, more preferably 4 to 15% by weight, based on the weight of the white filler. . If the compounding amount of the polyoxyalkylene glycol compound is less than 4% by weight, the processability is not sufficient, and if it exceeds 20% by weight, low heat generation is not obtained despite the increase in cost, which is not preferable.

In the rubber composition of the present invention, carbon black or the like can be used as a filler in addition to the white filler. The compounding amount of carbon black contained in the rubber composition of the present invention is preferably 80 parts by weight or less based on 100 parts by weight of the rubber component. If the amount of the carbon black exceeds 80 parts by weight, the heat buildup is undesirably increased.

Examples of the carbon black that can be used in the present invention include, but are not limited to, HAF, ISAF, SAF, and the like.

The rubber composition of the present invention may further comprise, if necessary, a softener, an antioxidant, a filler other than the rubber component, a white filler, a coupling agent, and a polyoxyalkylene glycol compound. Compounding agents used in the general rubber industry, such as a vulcanizing agent, a vulcanization accelerator, and a vulcanization accelerator, can be appropriately compounded.

The rubber, white filler, silane coupling agent, and polyoxyalkylene glycol compound are preferably mixed at a discharge temperature of 150 ° C. or less. 150 ° C
Above, there is a tendency that the phenomenon of rubber burn occurs.

[0032]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but these do not limit the present invention.

Various reagents used in Examples and Comparative Examples are shown below. Diene-based synthetic rubber: SBR1502 (styrene-butadiene copolymer) manufactured by Nippon Synthetic Rubber Co., Ltd. Silica: Ultrasil VN3 (manufactured by Degussa) (nitrogen adsorption surface area: 180 m ² / g) Silane coupling agent: manufactured by Degussa Si69 (chemical name: bis (3-triethoxysilylpropyl) tetrasulfide) Antioxidant: Nocrack 6C manufactured by Ouchi Shinko Chemical Co., Ltd. (chemical name: N- (1,3-dimethylbutyl) -N ' -Phenyl-p-phenylenediamine) Stearic acid: Stearic acid manufactured by NOF CORPORATION Zinc oxide: Zinc flower No. 1 manufactured by Mitsui Kinzoku Mining Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator TBBS: Noxeller NS (chemical name: N-tert-butyl-2-benzothiazyl sulfenamide manufactured by Ouchi Shinko Chemical Co., Ltd.) ) Vulcanization accelerator DPG: Noxeller D manufactured by Ouchi Shinko Chemical Co., Ltd. (chemical name: N, N'-diphenylguanidine)

The polyoxyalkylene glycol compounds used in Examples and Comparative Examples are shown below.

(Polyoxyalkylene glycol compound) (1) HO (CH ₂ CH ₂ O) ₉ H (manufactured by NOF Corporation, PEG 400) (average molecular weight: 400) (2) HO (CH ₂ CH ₂ O) ₁₄ H (Nippon Yushi Co., Ltd., PEG600) (Average molecular weight: 600) (3) CH ₃ O (CH ₂ CH ₂ O) ₉ H (Nippon Yushi Co., Ltd., UNIOX M-400) (Average molecular weight) : 400) (4) Diethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) (5) Triethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) (6) PEG 4000 (manufactured by NOF Corporation, PEG 4000) (Average molecular weight: 4000)

In Examples and Comparative Examples, the processability, rolling resistance, abrasion resistance, and wet skid performance of the obtained various rubber compositions were measured and determined by the following methods.

(Workability) Measured at 130 ° C. according to the Mooney viscosity measurement method specified in JIS K6300.
The Mooney viscosity (ML _{1 + 4} ) of Comparative Example 1 was set to 100 and expressed as an index by the following formula. The larger the index, the lower the Mooney viscosity and the better the processability. Workability index = tan δ of Comparative Example 1 / tan δ of each formulation ×
100

(Abrasion resistance) Using a Lambourn abrasion tester, the measurement conditions were measured at a temperature of 20 ° C., a slip ratio of 20%, and a test time of 5 minutes, and the volume loss of each compound was calculated.
The loss amount of Comparative Example 1 was set to 100, and an index was represented by the following formula. The larger the index, the better the wear resistance. Lambourn abrasion index = Loss of Comparative Example 1 / Loss of each formulation × 100

(Rolling Resistance Characteristics) Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho) at a temperature of 70 ° C.
The measurement was performed under the conditions of an initial strain of 10% and a dynamic strain of 2%.
The tan δ of each formulation was measured, and the tan δ of Comparative Example 1 was 10
It was set to 0 and expressed as an index by the following formula. The larger the index, the better the rolling resistance characteristics. Rolling resistance characteristic index = tan δ of Comparative Example 1 / t of each formulation
anδ × 100

(Wet skid performance) ASTM E3 using a portable squid tester manufactured by Stanley
It was measured according to the method of 03-83, and was expressed as an index by the following formula. The higher the index, the better the wet skid performance. Wet skid performance index = numerical value of each formulation / numerical value of comparative example 1 × 100

Examples 1 to 5 and Comparative Examples 1 to 9 Using the polyoxyalkylene glycol compounds of (1) to (6), rubber compositions were prepared according to the formulation shown in Tables 1 to 3. As a kneading method, for example, a rubber component is first heated to 100 to 150 ° C. using a Banbury mixer or the like.
Mastication for 1-2 minutes, and then kneading of components other than the vulcanizing agent and the vulcanization accelerator at 100-150 ° C for 2-4 minutes, and the temperature of the discharged rubber of the rubber composition is as shown in Tables 2-3. It was discharged to become. Subsequently, a vulcanizing agent and a vulcanization accelerator were blended and kneaded using an open roll or the like to obtain various rubber compositions. These rubber compositions were press-vulcanized at 170 ° C. for 20 minutes to obtain a vulcanized product, and each property was measured by the above method.

Tables 2 and 3 show the results obtained in each of the examples and comparative examples.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

According to the present invention, a rubber composition having improved abrasion resistance, low heat build-up (rolling resistance), and improved processability without deteriorating wet skid performance can be obtained.

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Claims (2)

[Claims] 1. A natural rubber and / or a diene-based synthetic rubber containing a white filler as a filler, having the following general formula (I): Y ₃ —Si—C _n H _2n A (I) (formula (I) during I), Y is an alkyl group having 1 to 4 carbon atoms, alkoxyl group or a chlorine atom, three of Y may be the same or different, n represents an integer of 1 to 6, a is -S _m C _n
H _2n Si-Y ₃ group, a nitroso group, a mercapto group, an amino group, an epoxy group, a vinyl group, a chlorine atom, imido group and -S _m Z group (wherein, m is an integer from 1 to 6, n and Y is the same as above, and Z is the following chemical formula
(II), a group represented by the chemical formula (III) or the chemical formula (IV)); % Embedded image Embedded image Further, the following general formula (V): R ¹ O (R ² O) _n H (V) (In the formula (V), R ¹ is hydrogen or an alkyl group having 1 to 6 carbon atoms, R ² is a methylene group, An ethylene group, a propylene group, and a tetramethylene group, all of which may be the same or different, n is an integer of 1 or more and 20 or less, and the molecular weight of the polyoxyalkylene glycol compound is 200 to 1,000. ) Is added to the white filler in an amount of 4 to 20.
Rubber composition containing by weight. 2. The method for producing a rubber composition according to claim 1, wherein the white filler, the silane coupling agent, and the polyoxyalkylene glycol compound are mixed at a kneaded rubber discharge temperature of 150 ° C. or lower.