JPS61225228A - Rubber composition - Google Patents

Abstract

PURPOSE:A rubber composition excellent in green strength and moldability and capable of giving a vulcanizate excellent in resiliency, comprising polyisoprene rubber modified with a Lewis acid, COOH group-containing polyisoprene rubber, etc. CONSTITUTION:100pts.wt. polyisoprene of a cis 1,4-bond content >=90%, etc., are dissolved in a solvent in a concentration of 1-30wt%. This solution is mixed with 0.1-5pts.wt. Lewis acid such as SnCl4 and reacted at -20-100 deg.C for 2min-10hr by using such a modifying condition that the glass transition temperature can be increased by 0.3-2.7 deg.C as compared with that of the starting polyisoprene and the Wallace poasticity can be increased by 2-35 points as compared with that of the starting material to obtain a Lewis acid-modified polyisoprene rubber (A). 100pts.wt. polyisoprene rubber in a state dissolved in an organic solvent or in the absence of a solvent is kneaded with 0.01-20pts. wt. modifier such as maleic anhydride in the presence of heat or a peroxide to obtain a COOH group-containing polyisoprene rubber (B). 1-99wt% component A is mixed with 99-1wt% component B.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is characterized by the fact that by mixing Lewis acid-modified polyisoprenoco or futo carboxyl group-containing I-linzolene rubber,
This invention relates to an invention that improves both the green strength of the carbon-containing unvulcanized product and the rebound modulus of the vulcanized product.

(Prior Art) Conventionally, carboxyl groups have been introduced as a rubber for the purpose of obtaining rubber compositions with improved green strength. For example, a method of reacting hydroxamylkloric acid such as maleic anhydride or terephthalohydroxamylchloridic acid (
Special Publication No. 48-10635') is known. Furthermore, a reaction is known in which polyisoprene rubber is treated with a Lewis acid such as SnCj 4 for the purpose of obtaining a rubber composition with improved rebound properties (Japanese Patent Laid-Open No. 59-81301).

However, these modification reactions were unable to improve both the green strength and rebound resilience of the rubber, and were particularly insufficient to meet the performance requirements of tire materials.

(Problems to be Solved by the Invention) Therefore, the inventors of the present invention sought to improve green strength and rebound resilience. f? As a result of various studies to develop IJ isoprene rubber, we found that by mixing Lewis acid-modified I-isoprene rubber and carboxyl group-containing polyisoprene rubber, both green strength and rebound modulus were synergistically improved. The inventors have discovered that it is possible to do this, and have completed the present invention.

(Means for Solving the Problems) That is, the present invention provides a patented parabolite characterized by containing a polyisoprene rubber modified with a Lewis acid and a polyisoprene rubber containing a carboxyl group. be.

The polyisoprene rubber modified with a Lewis acid in the present invention can be obtained from a solution of pre-isoprene rubber dissolved in an organic solvent or after completion of polymerization. It is obtained by treating lysogrene rubber cement in solution with a Lewis acid.

The polyisoprene rubber used as a raw material here is preferably preisoprene having a ratio of cis-1.4 bonds of 90 or more, which is polymerized using a Ziegler type catalyst or a lithium-based catalyst.

Examples of solvents include aromatic solvents such as benzene and toluene,
Any arbitrary solvents such as paraffinic solvents such as butane and hexane, cyclofluorinated solvents such as cyclohexane, and 7-rhodanized hydrocarbon solvents such as chloroform and ethylene dichloride can be used alone or in combination. However, alcohol.

The amount of solvents that are active against Lewis acids, such as ketones and ethers, is limited. The concentration of rubber in solution is 1
It is appropriately determined within the range of 30% by weight. Further, it is desirable that the water content in the solution is usually 400 ppm or less.

Generally known Lewis acids can be used for the modification reaction, and representative examples thereof include metal or semimetal rhodanides, such as Be, B+A, and Si.
+P, S, Tf, V+Fe5Zn, Ga, Go, As,
Se+Zr, Nb, Mo, Cd, 8n, Sb, To,
Elements such as TatWsHglBl+U or PO, S@O
, So, 802, VO, etc., or organic halides of oxygen-element bonds, or complexes thereof. More specifically, BF3. (CH
3) 2BF e AlCl3. A7Brse(C2H
5) AjCJ2, POCj, #TICJ4
, VCl4, Mo(J6.

(CH3)5nCnoseT@Br4, etc., particularly preferably BF30(C2H5)2, 5nCj4t
5bCj5 m WCl6 e 8nBr4 eBC
Examples include j5 + T@Cj4.

The amount of Lewis acid required for modification is greatly influenced by the type of solvent, water in the solution, and other coexisting substances, so it cannot be generally specified, but it is usually 0.1 parts by weight per 100 parts by weight of polyisoglyne copolymer. ~5 parts by weight. In addition, by coexisting an appropriate amount of metal compounds having active hydrogen such as trichloroacetic acid, tribromoacetic acid, water and methyl alcohol, and halides such as t-butyl chloride and pencil chloride, the amount of Lewis acid can be adjusted. can be significantly reduced. The reaction temperature during modification with a Lewis acid is not particularly limited, and is usually -20°C to 100°C, preferably 10°C to 60°C. The reaction time is also not particularly limited, and is usually appropriately set between 2 minutes and 10 hours. After adding Lewis acid to a solution of polyisogrene rubber and treating it for a specified time with stirring, adding a large amount of alcohol or hot water will stop the reaction and coagulate the rubber. A modified rubber is then obtained by washing and drying.

The above modification conditions with Lewis acid have a glass transition temperature of 0.3°C to 2.0°C compared to polyisogrene rubber before modification.
．． It is desirable to select such that the temperature increases by 7°C and the Wallace plasticity increases by 2 to 35 points. When the increase in glass transition temperature or Wallace plasticity is lower than the above range, the improvement in rebound resilience and heat generation property is insufficient, and when it is higher than the above range, the rebound modulus is rather reduced.

Performance deteriorates due to increased heat generation. Further, it is desirable that the processing conditions with Lewis acid be selected so as to minimize the generation of hydrogen. When unmodified lysoprene has a significantly increased amount (for example, 10% or more) compared to siloprene, processability may deteriorate.

In the present invention, the carboxyl group-containing polyisogrene rubber refers to carboxyl group-containing polyisogrene rubber in a solution state in which polyisogrene rubber is dissolved in an organic solvent, or in a rubber kneader in the absence of a solvent.
This is a rubber obtained by introducing xyl groups.

The above carboxyl group introduction reaction method is not particularly limited, but specific examples thereof include maleic anhydride addition reaction (CA' 79
(2) 6643Z), a method of reacting hydroxamyl chloride acid such as terephthalhydroxamyl chloride acid (Japanese Unexamined Patent Publication No. 10635/1983).

Addition reaction of 3-carboxylphenylmaleimide (
Kauch Rezina 1978 8-10 Ch
avchich.

T ＠tal) sMethod of introducing a carboxyl group by reacting metal carboxylic acid with carbon monoxide in the presence of carbonyl (CA'
77(12)76298P), cargexyl group introduction reaction using 4-cargoxyl-phenyl-1,2,4-) riazoline-3,5-dione (JP-A-49-8647)
7) etc.

The solvent and reaction conditions (temperature, pressure, 1 hour) used in the carboxyl group introduction reaction are generally selected from the same range as in the modification reaction with Lewis acid described above, but more specifically, the reaction, The conditions described in the above-mentioned documents and patents may be adopted depending on the method.

The amount of the above-mentioned modifier used in the carboxyl group introduction reaction is not particularly limited, but is usually 100 parts by weight! ! 70.01 to 20 parts by weight, preferably 0.1 to 20 parts by weight
It is 10 parts by weight.

The mixing ratio of the Lewis acid-modified polyisoprene rubber and the calxyl group-containing polyisoprene rubber is appropriately selected from the range of 1 to 99% by weight for the former and 99 to 1% by weight for the latter, depending on the purpose.

The method of mixing the combs in the present invention is not particularly limited, but usually a method is used in which a polymer solution after a modification reaction is mixed using a stirrer, or a method in which various types are mixed using a comb kneader.

In addition, in particular, after premixing car-gantura, resin, and various process oils with modified polyisogrene rubber and/or carboxyl group-containing I-lysosolene rubber to form carton masterbatches and oil masterbatches, the rubbers can be mixed together. can also be mixed.

(Effect of the invention) Iliiso! of the present invention! A rubber compound obtained by mixing a rubber composition with conventional rubber compounding agents such as a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, a reinforcing agent and a softening agent, and optionally other conventional rubber compounds. The vulcanized compound exhibits excellent green strength, making it extremely easy to process.Also, this vulcanized product has excellent strength properties and rebound resilience, so it can be used not only for general purposes, but also for the purpose of achieving these properties. It is particularly applicable to required applications such as tire carcass and tread, anti-Micro-imprint rubber, etc. However, it is also possible to use the composition of the present invention in the form of a latex for ordinary latex applications.

(Example) Next, the present invention will be specifically explained using examples.

The methods for analyzing the rubber on each side, the methods for preparing unvulcanized rubber compounds and vulcanized products, and the methods for testing their physical properties are as follows.

〔Glass-transition temperature〕

Daini Seiko Kin High Sensitivity Differential Scanning Calorimeter (DSC) SSC-
560 was used to find the inflection point of the measurement curve.

[Wallace plasticity]

100℃ using Wallace Rapid Blastmeter
It was measured with

[Amount of carboxyl group introduced into the gum]

After purifying and removing the low-molecular components in the liquid, the sample was measured by neutralization titration (back titration with sodium methylate/hydrochloric acid).

[Preparation of unvulcanized rubber compound] The rubber was cross-mixed in a small Banbury mixer with various compounding ingredients other than sulfur and vulcanization accelerator in the following compounding recipe (selected depending on the type of rubber). Then, sulfur and a vulcanization accelerator were added to the resulting mixture and kneaded on a small roll to prepare an unvulcanized rubber compound.

Blending recipe f 100 (parts by weight) HAF carne 50 Aromatic oil 5 Zinc oxide 5 Stearic acid 2 Sulfur 2.5 [
Green strength] The unvulcanized rubber compound was press-molded at 100°C for 5 minutes to form an unvulcanized rubber sheet with a thickness of 21II, and dumbbell-shaped JIS No. a test pieces were punched out at 25°C.
Elongation 50 when performing a tensile test with a tensile strength of 7 min
It is shown as the value of tensile stress at 0%.

[Tensile test]

The unvulcanized rubber compound was press-vulcanized at 145°C for a predetermined period of time to form a 2N thick sheet, and a dumbbell-shaped No. 3 test piece specified by JIS-6301K was punched out and heated at 25°C for 500 tx.
The tensile speed was 1/min.

[Repulsion Resilience] Measured at 25°C using a Dunlop trypne meter.

Example 1 Polyisoprene rubber (98% cis 1.4 bonds) 160t
was dissolved in dehydrated benzene of No. 41, and the Lewis acid and cocatalyst listed in Table 1 were added as a benzene solution, respectively, at 25° C. under a nitrogen atmosphere while stirring in a glass closed container (Set! Rubble Flask). After reacting under the conditions shown in Table 1, 100 m+7 methanol was added to stop the reaction. The obtained comb solutions are designated as A and B.

On the other hand, polyisogrene rubber (98% of cis 1.4 bonds) 1
60iP for 41! The compounds listed in Table 2 were dissolved in benzene and stirred in a glass airtight container (Se/4 Rubble Flask) at 60°C under a nitrogen atmosphere as a methanol solution. After reacting for 3 hours, 36 HCj 201
The reaction was stopped by adding 200 d of methanol in which 117 was dissolved. The resulting carboxyl group-introduced polyiso! The Renco Om solution is referred to as C9D.

? Lysogren rubber solution A, B and Cal? After mixing the xyl group-introduced polyisoprene rubber solutions C and D in the proportions shown in Table 3, the reaction solution was poured into methyl alcohol No. 41 to completely coagulate the rubber, and the coagulated material was washed as small pieces. did. t f , about 2 j' anti-aging agent (
A rubber composition was obtained by soaking the coagulated pieces in all methyl alcohol containing 2,6-di-tert-butyl-4-methylphenol, washing them, and drying them in a vacuum dryer overnight. .

For comparison, a rubber composition was obtained by treating the same benzene solution of unmodified I-lisoprene rubber as above or a mixed solution of this with solution A or C in the same manner as above.

Next, unvulcanized compounds and vulcanized products were prepared using each rubber composition, and their physical properties were measured. The results are shown in Table 3.

Example 2 Polyisoprene rubber (cis 1.4 bonds 9g%) 160.
Dissolve 9 in 47 dehydrated benzene and place in a glass airtight container (
The Lewis acids and cocatalysts listed in Table 4 were each added as a benzene solution at 25°C under a nitrogen atmosphere while stirring in a 7-year-old flask, and reacted for 60 minutes.
The reaction was stopped by adding methanol (d). The resulting rubber solution was poured into 81 methanol to coagulate the plum, and the coagulated material was washed in pieces. Next, 2I anti-aging agent (2
Sample 1. I got an F.

On the other hand, polyisoprene gum (98% of cis 1.4 bonds) 1
60g was dissolved in 41g of toluene and reacted under the reaction conditions listed in Table 5 under a nitrogen atmosphere while stirring in a closed glass container (7-paraple flask).
．． The mixture was poured into a 1% methanol solution 31 of 6-di-tert-butyl-4-methylphenol to completely solidify the gum, and the solidified product was washed in pieces. Thereafter, samples G and H were obtained by drying in a vacuum dryer for a day and a night.

The obtained samples B-H were mixed in a small-sized pum kneader according to the formulations shown in Table 6, and the physical properties were evaluated in the same manner as in Example 1 together with the comparative examples.

From Tables 3 and 6, it can be seen that the compositions of the invention examples are significantly superior in both green strength and rebound modulus in a well-balanced manner compared to the compositions of the comparative examples.

Claims (1)

[Claims] A rubber composition comprising a Lewis acid-modified polyisoprene rubber and a carboxyl group-containing polyisoprene rubber.