JPH01197542A - Rubber composition for tire - Google Patents

Abstract

PURPOSE:To obtain the title rubber composition improved in heat resistance, by mixing a stock rubber comprising a halogenated isoprene polymer and other conjugated diene polymers with a polyamide. CONSTITUTION:Natural rubber or polyisoprene is reacted with an organic halogenating agent in an organic solvent to obtain a halogenated isoprene polymer (a) having an allylic halogen structure and a halogen content of 0.3-5.0wt.%. 30-100 pts.wt. component (a) is mixed with 70-0 pt.wt. other conjugated diene polymers (b) to obtain a stock rubber. 100 pts.wt. said rubber is mixed with 0.3-10 pts.wt. polyamine (e.g., N,N'-diphenyl-p-phenylenediamine).

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a rubber composition for tires, particularly a coating rubber composition with excellent heat resistance used for pneumatic tires that are used continuously at high temperatures. The present invention relates to an inner liner rubber composition.

(Conventional technology) In recent years, as automobiles have become faster and faster, the operating temperatures of tires have become higher and higher, and the remarkable deterioration of rubber properties due to high temperatures has caused a decline in tire durability, and countermeasures have been strongly required. ing.

Conventionally, this kind of thermal deterioration has been prevented by using rubber compositions with low heat build-up that make it difficult for the tire itself to heat up, but this method also works because rubber is a viscoelastic material As long as it is, there is a limit. Other techniques have also been proposed, such as increasing the number of monosulfide bonds, which have relatively high heat resistance, in cross-linking.
Its effectiveness is insufficient.

(Problems to be Solved by the Invention) The above-mentioned method of increasing the number of monosulfide bonds in cross-linking is still insufficient in improving heat resistance, but in order to minimize high-temperature deterioration of rubber, it is necessary to Improving thermal stability remains particularly important.

In this context, it is known that chlorobutyl and bromobutyl provide a highly heat-resistant crosslinked structure with aromatic amines, such as N,N'-diphenyl-p-phenylenediamine (D.C. Edwards). ,C,B
dwards), Rubber Chemistry & Technology (R, C, T) Vol. 60, p. 62, 1987).

However, in order to obtain such halogenated rubber from isoprene-based polymers such as natural rubber or polyisoprene rubber, which are often used in tire coating rubber compositions and inner liner rubber compositions, for example, toluene of polyisoprene rubber is used. ? G? (When chlorine gas is blown into l, polyisoprene containing active halogen groups is obtained, but at the same time IIcI is generated, (1) chain scission of the polymer causes a significant decrease in molecular weight, and (2) IIcI is generated. CI causes an addition reaction to the polymer, -
Since the active halogen groups once formed are rendered inactive, isoprene-based polymers containing satisfactory active halogen groups have not been obtained.

Furthermore, another known method is to put polyisoprene rubber and a chloramine compound into a mixer and knead them, but the resulting chlorinated polyisoprene has an extremely low content of active chlorine groups, Satisfactory crosslinking cannot be obtained.

Therefore, a polyisoprene rubber composition that provides a crosslinked structure with high heat resistance has not yet been obtained.

(Means for solving the problem) As mentioned above, we focused on the fact that the thermal stability of crosslinking largely controls the heat resistance of rubber, and as a result of intensive study, we found that natural rubber and polyisoprene having an allyl halogen structure It has been discovered that when crosslinked with a polyvalent amine, excellent heat-resistant crosslinking is provided, and this invention has been completed.

That is, the present invention comprises 30 to 100 parts by weight of a halogen-containing isoprene polymer having an allyl halogen structure and a halogen element content of 0.3 to 5.0% by weight, and 70 parts by weight of another conjugated diene polymer. This is a rubber composition for tires comprising 0.3 to 10 parts by weight of a polyvalent amine to 100 parts by weight of raw rubber consisting of 0 parts by weight.

The halogen-containing isoprene polymer having an allyl halogen structure used in this invention is a halogenated natural rubber or a halogenated polyisoprene rubber having an allyl halogen structure, and such rubber is based on the findings of the present inventors. A novel method allows natural rubber or polyisoprene to be treated with an alkylhyphohalite such as tertiary-butoxychloride, an N-heroamide compound such as N,N-dichlorobenzenesulfonamide, or trichloroisocyanuric acid in an organic solvent. It can be suitably produced only by halogenation by reaction with an organic halogenating agent selected from trihaloisocyanuric acids such as.

The content of the halogen element having an allyl halogen structure in the halogen-containing isoprene polymer used in this invention must be 0.3 to 5.0 tffi%, and 0.5 to 3.0 tffi%. % is preferable. If the halogen content is less than 0.3% by weight, a sufficient crosslinking density cannot be obtained, while if it exceeds 5% by weight, the problem of burning during processing will occur.

The amount of the halogen-containing isoprene polymer in the raw material comb must be at least 30 parts by weight in order to obtain sufficient heat resistance of the crosslinked rubber. Other conjugated diene polymers to be blended are not particularly limited, but commonly used natural rubber, polyisoprene rubber, emulsion styrene butadiene rubber, solution polymerized styrene butadiene rubber, polybutadiene rubber, etc. be.

The polyvalent amines used in this invention include aliphatic or alicyclic amines such as hexamethylene diamine, heptamethylene diamine, methylene bis(cyclohexylamine), 1,3-di-4-piperidylpropane, and 414'-dipiperidyl. Primary or secondary diamines, alicyclic tertiary diamines such as triethylene diamine, aromatic primary diamines such as 4,4'-methylene dianiline, N, N'
Aromatic secondary diamines such as -diphenyl-p-phenylenediamine and di-β-naphthylphenylenediamine, and trivalent or higher valent amine compounds such as diethylenetriamine, triethylenetetramine, and tetraethylenepentamine are mentioned, and particularly preferred ones include N,N'-diphunyl-p-phenylenediamine is mentioned. The amount of added amine is 0.3 to 10 parts by weight, preferably 0.5 to 5 parts by weight.
Parts by weight are used. If it is less than 0.3 parts by weight, sufficient crosslinking cannot be obtained, while if it exceeds 10 parts by weight, there is a problem in terms of scorch.

Further, in the rubber composition of the present invention, it is possible to use a commonly used crosslinking agent such as sulfur, a vulcanization accelerator, and a vulcanization accelerating aid.

Carbon black such as GPF, process oil, etc. are also used as appropriate.

(Examples) Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

-1 to 3 6 1 to 4 polyisoprene rubber (manufactured by Japan Synthetic Rubber Co., Ltd., JSRlR2200
; cis content 98%) Dissolve 100g in 22g of toluene and add N to this while stirring in a separable flask.
, N-dichlorobenzenesulfonamide 2.66 g'
(0,012 mol/100 g elastane ÷-) was added as 120 d of toluene solution and reacted at 50"C for 8 minutes. Thereafter, the reaction solution was mixed with 40 g of anti-aging agent (2,6-
The elastomer was poured into methanol 81 containing di-L-butyl-4-methylphenol (BIT) to coagulate it, and after thoroughly washing the coagulated material into pieces with fresh methanol containing BIT, it was dried in a vacuum dryer overnight. Sample B was thus obtained. The halogen content (weight%) of this sample is 0
．． It was 5%. Sample B was subjected to "C-NMR and 'H-
As a result of structural analysis using NMR, it was found that it had the following allyl halogen structure.

I Further, by changing the amount of the halogenating reagent in the same manner, Sample C had a halogen content of 2.0% by weight, and Sample D had a halogen content of 6.0% by weight.

This sample, polyisoprene rubber (JSRlR2200), and natural rubber were kneaded in a small Banbury mixer with the formulation shown in Table 1 to form a rubber composition.

Table 1 ■Su, Summer Polymer 100 HA F 50 Stearic acid 2 Polyvalent amine 91 Variable zinc white 5 M5A" 1 Sulfur 2.5 ml N,N'-diphenyl-p-phenylenediamine 12 N-oxydiethylene-2 -Benzothiazolylsulfenamide Table 2 shows the results of evaluating various physical properties after crosslinking at 145°C for 60 minutes of various rubber compositions with different polymer types and polyvalent amine amounts as shown in Table 1. As a measure of heat resistance, the breaking strength (Tb) after aging was measured.

<74a7'A11'IC" J round to Kiri, 14-6
15-7 Compositions corresponding to Examples 1-3 and Comparative Examples 1.3 and 4 were further prepared and applied to inner liners of radial tires for trucks and buses having a 1000-20 14-ply rib pattern. 5 Mainly on expressways due to tires
After running for a long time, the state of deterioration of the inner liner was measured. The results are shown in Table 3.

Table 3 Book 1 The smaller the value, the better. However, when the composition shown in Comparative Example 2 was used for an inner liner, it was not possible to manufacture a tire due to scorching.

The evaluations shown in Examples and Comparative Examples were performed by the following method.

Scorch time: JIS Mooney scorch time
Aging test measured according to Section K6300-5 (Table 2): Aging test was carried out according to Section 6301-6, except that an air heating aging test was conducted at an aging temperature of 150 DEG C. and an aging time of 15 hours.

Hardness measurement test Nispring hardness test JTS K360
The procedure was carried out according to Section 15.

(Effects of the Invention) As is clear from the test results shown in Tables 2 and 3, the tire rubber composition of the present invention combines a halogen-containing isoprene polymer having a specific amount of a halogen element with an allyl halogen structure and a polyvalent The heat resistance of the rubber composition is significantly improved over conventional rubber compositions.

Therefore, the tire rubber composition of the present invention can be applied to coating rubbers, inner liner rubbers, tread rubbers, bead filler rubbers, etc. that require heat resistance, and can significantly improve heat resistance.

Patent Applicant: Brideston Co., Ltd. Patent Attorney Akihide Sugimura

Claims (1)

[Claims] 1. Has an allyl halogen structure and halogen element content is 0.
．． 0.3 parts by weight of a polyvalent amine per 100 parts by weight of raw material rubber consisting of 30 to 100 parts by weight of a halogen-containing isoprene polymer of 3 to 5.0 parts by weight and 70 to 0 parts by weight of other conjugated diene polymers. -10 parts by weight of a rubber composition for tires.