US3135624A

US3135624A - Method of treating rubber-reinforcing material

Info

Publication number: US3135624A
Application number: US125081A
Authority: US
Inventors: Nakane Takashi; Kubota Takeo; Umezawa Yoshiro
Original assignee: Yokohama Rubber Co Ltd
Current assignee: Yokohama Rubber Co Ltd
Priority date: 1960-07-25
Filing date: 1961-07-19
Publication date: 1964-06-02
Anticipated expiration: 1981-06-02
Also published as: GB986614A

Description

'and the reinforced rubber.

United States Patent METHOD OF TREATING RUBBER-REINFORCING The present invention relates to methods of treating rubber-products-reinforcing fibrous material for improving physical properties such as tensile-strength, heat resistance, fatigue resistance and adhesion properties of the rubber products at ordinary temperature and under exothermic conditions.

In many cases, fibrous material which is to serve as a rubber reinforcement is required to have substantial resistances to heat, Water and fatigue. Particularly in major rubber products such as automobile tires and conveyer belts, resistances to heat, Water and fatigue are critical, and the performance of such products, in fact, largely depends upon such characteristic properties, as is well known in the art. Resistances to heat, Water and fatigue are required for both fibrous reinforcing material per se and for the adhesive bonds between such material In other words, fibrous rubber-reinforcing material for industrial use not only must have itself substantial resistances to heat, water and fatigue but also must have a substantial adhesive strength with respect to the rubber reinforced by the fibrous material. In addition, such adhesion is required to be heatand Water-resistant as well as dynamically resistant to fatigue load.

An object of the present invention is to provide a method of treating fibrous rubber-reinforcing material for enhancing the strength of the material per se as Well as the adhesive strength thereof with respect to rubber material. According to the present invention, there is provided a method of treating fibrous material adapted for the reinforcement of rubber products such as tires, belts or hoses, for example, natural or synthetic fibrous material in the form of tire cords or belt duck characterized by the immersion of such material in a dilute solution, dispersion or emulsion of drying oil or semidrying oil essentially comprised of fatty acid glycerides containing metal soap as described hereinafter. This method, it has been found, imparts to the fibrous material substantial resistances to water and heat, as well as flexibility and improved adhesive strengths under heated conditions and resistance to fatigue load.

The diluted treating composition of drying oil or semidrying oil principally comprised of fatty acid glycerides including metal soap is, according to the present invention, either a dilute solution thereof in an organic solvent having a concentration of not more than 10%, but preferably not more than 5%, or a dilute emulsion of such oil dispersed and emulsified in water having a concentration of not more than or preferably not more than 5%.

According to the present invention, the application of such treating composition onto fibrous material may be effected at the spinning stage, or application may be effected or may be performed after the spinning stage upon fibrous material in the form of yarns, cords or fabrics. Application may also be effected by employing an RFL (resorcin-formalin-latex) solution to which is added the treating composition for the adhesive treatment of the cords or fabrics this method comprising immersing such cords or fabrics in the mixture or spreading the latter over such cords or fabrics. In either case, the application of such treating compositionis performed 3,135,624 Patented June 2, 1964 ICC during or immediately before or after the adhesive treatment.

In case the treatment of fibers is effected at the spinning stage, such treatment is effected either by incorporating the treating composition into the finishing agent used at the step of oiling, or it is effected before or after the usual oiling process.

The metal soap contained in the treating composition according to the present invention has the general formula [CH -(CH -CO Me, and a melting point of C. or under. In this formula, Me is a divalent 'metal, and n is a positive integer of 8 to 18.

In the treatment of fibrous material with such metal soap, the metal soap is compounded with a drying oil or semidrying oil, the proportion of the metal soap to the drying or semidrying oil being 50% or less. The drying oil or semidrying oil compounded with the metal soap is dissolved in an organic solvent to form a dilute solution having a concentration of 10% or less. An alternative method of preparing such dilute solution is to disperse the drying or semidrying oil added with the metal soap in water to form a water emulsion having a concentration of 10% or less. The dilute solution thus prepared of drying or semidrying oil containing metal soap should have a concentration of 10% or less, or preferably 5% or less.

This treatment of fibrous material according to the present invention is preferably effected so that the fibrous material after immersion treatment have a solids pick-up'of under 5% by weight of the fibrous material.

The fibrous material thus treated, when used as a I rubber-reinforcing material, exhibits itself striking improvements in water resistance, flexibility, and heatand fatigue-resistances, the adhesive bond formed between the fibrous and rubber materials also exhibiting improved resistances to heat, water and fatigue thereby securing a satisfactory adhesion between the two materials.

Many of major rubber products such as tires, rubber belts and rubber hoses comprise a combination of rubber and fibrous material as a reinforcement therefor, the effective service life of such products depending on the performances of the reinforcing material used and the adhesive bond formed between the rubber and the reinforcing material.

The method of treating rubber-reinforcing material in accordance with the present invention, in effect, extends the service life of rubber products reinforced by the material and improves the qualities thereof, and this is evident from the results of laboratory researches and practi cal tests performed by the inventors.

A number of practical examples will now be specifically described.

EXAMPLE 1 The method of the present invention was applied to high-tenacity rayon while it was being spun into yarns of 1650 D. Oiling is generally used in spinning ordinary high-tenacity rayon yarns of 1650 D. Good results were obtained by replacing part or all of the common tire cord oil used in such oiling by a dilute solution of drying or semidrying oil admixed with metal soap in accordance with the present invention. In this example, 70 parts of the oil was replaced by the oil preparation according to the present invention. The metal soap used was cadmium stearate, and the vegetable oil was soy bean oil which is a drying oil. The compounding ratio of the diluted liquid composition used was as follows:

6% water emulsion used: Parts Water dispersion of Cd-stearate 20.00 Water 70.00 Soy bean oil 10.00

A 6% water emulsion containing 2% of Cd-stearate and 4% of soy bean oil.

Dimol N: Partially desulfonated Na ligno sulphonate. 2 Aerosol OT Sodium dioctyl sulfosuecinate.

A water dispersion of Cd-stearate.

Water emulsion of soy bean oil: Parts Soy bean oil 4.0 Casein 0.1 NH OH 0.1 Water 5.8

A 40% water dispersion of soy bean oil.

Firstly, a water dispersion of Cd-stearate was prepared. The quantity of water as defined above was heated to about 50 to 60 C., and then Aerosol OT, Dirnol N and sodium alginate were successively added to and dissolved in the water with stirring. After cooling the resultant solution to the room temperature, Cd-stearate was gradually admixed to the solution with stirring to form a homo geneous mixture. This mixture was subjected to the action of a ball mill for to 24 hours to give a 10% water dispersion of Cd-stearate.

A water emulsion of soy bean oil was separately prepared. The amount of water as specified in the above recipe was heated to about 60 to 70 C. After 28% aqueous ammonia and casein were completely dissolved in the heated water with stirring, soy bean oil was gradually added while agitating the solution. Then, the mixture was homogeneously dispersed by a homogenizer to form a 40% water emulsion of soy bean oil.

70 parts of water was added with stirring to parts of the prepared water dispersion of Cd-stearate to form a complete mixture. To this, 10 parts of 40% emulsion of soy bean oil was added with stirring and the mixture was passed once through a homogenizer to complete the preparation of the inventive treating composition. In this example, 6% water emulsion containing 2% of metal soap and 4% of vegetable oil was used.

The 6% emulsion thus prepared (containing Cd-stearate 2% and soy bean oil 4%) was mixed with usual tire cord oil in a proportion such that about 70% of the solids con tent in the oil preparation is formed of the solid ingredicnts of the treating composition prepared according to the present invention. In this example, 3% oil preparation was formed which contained per litre 9 grams of tire cord oil and 21 grams of the treating agent according to the present invention, and was used for oiling" in spinning high-tenacity rayon yarns of 1650 D. After oiling, the spun yarns were dried and wound up in the usual manner. The yarns thus treated exhibited remarkably improved waterand heat-resistance. The yarns were used to form tire cords of 1650 D/ 2 and 12 turns per inch both in upper and lower twist, which cords exhibited very excellent resistances to heat, water and fatigue as compared to those not subjected to the treatment of the present invention. The cords were further treated with resorcinformalin-latex in the usual manner and the adhesive characteristics of the cords thus treated were determined. The results include many noteworthy figures as follows, showing that the heatand water-resistant adhesive strengths were highly improved by the treatment.

Test Data of Example 1 Prior Present method, method, kg. kg.

Raw cord strength (bone dry) 13. 5 14.1 Strength of cord dipped in RFL (bone dry) 13. 9 14.5 Strength after heating for 5 hours at 165 C... 10. 3 13.2 Strength after heating for 10 hours at 165 C 9. 4 11.2 Adhesive strength of cord (II-test):

After heating for 1 hour at C 11.0 11.7 After heating for 1 hour at 160 C 6. 8 7. 6 After dipping in water for 24 hours 4. 4 5. 5

As clearly seen in the data, in this example, the tire cords exhibited excellent heat-resistant strengths and improved adhesive characteristics particularly under heated conditions.

The cords treated were further employed to form automobile tires which exhibited excellent performances.

Tires of the type 825-20-14 PR (12P) were prepared with the tire cords treated in accordance with this invention and subjected to indoor running tests under the following conditions: Speed, 40 miles/ hr. air pressure, TRA std; load, of TRA std and 10% up for each additional 250 miles.

The running life distance obtained was about 3800 km., which is about 40% up as compared with ordinary 825- 2014 PR (12?) tires, which had 2700 km. life. In the indoor running test on the tire which was built using the cords treated according to this invention, the growth of outer circumference and Width and heat generation in the tire were much less than those of the ordinary tire. These facts represent a remarkable improvement in tire qualities realized by the improvements in various properties of the tire cords as described above, demonstrating the successful effects of the present invention.

EXAMPLE 2 Immediately before the adhesive treatment of tirecords, the method of the present invention was applied thereto. The tire cord fabrics were preliminarily immersed in the diluted liquid composition of vegetable oil containing metal soap according to the present invention, dried and immediately subjected to the so-called tire cord dipping (resorcin-formalin-latex treatment).

The metal soap used in this example was zinc stearate, and the vegetable oil was cotton seed oil which is a semi drying oil, the diluent being an organic solvent. The treating process was as follows: Zinc stearate was dispersed in a mixed solvent of CCL; and methyl alcohol in proportion of 3 to 1 to give the Zn stearate content of 2.5%. Then, cotton seed oil was added with stirring to obtain a 5% solution of cotton seed oil. The resultant dilute solution thus contained 5% of cotton seed oil and 2.5% of zinc stearate. Tire cords were immersed in this treating solution before the usual dipping step. That is, the tire cord fabrics were preliminarily dipped in the treating solution of the present invention with the cords held in light tension. After removing any excess of the solution thus applied to the fabrics by means of a squeeze roll, the fabrics were dried so that the cords had a water content of 15% or less, or preferably 5% or less. In

ing such cords also exhibited an extended running life. After the indoor running test of 1000 km., the tire was cut and tested for cord and adhesive strengths, which showed remarkable improvements as follows:

Prior Present 1650 D/2 high-tenacity rayon cord method, method,

kg. kg.

Strength of cord (bone dry) 14.1 15.0 Strength after heating for 5 hours at 165 0... 11.4 13. 5 Strength after heating for hours at 165 C 9i 7 11.5 Strength after 1,000 km. indoor running test 12. 7 13. 7 Cord adhesive strength (H-test):

After heating for 1 hour at 130 C 10. 5 11.0 After heating for 1 hour at 160 C" 7.0 7. 7 After immersion in water for 24 hours 4. 3 5.0 Adhesive strength:

After 1,000 km. indoor running test 1 19. 2 26. 2

1 Peeling between 9th and 10th plies in tire type 825- 14 PR (121 As apparent from the foregoing description of typical practical examples where rayon tire cords were sub-' jected to the reinforcing treatment according to the present invention, the cords treated according to the present invention exhibited improved resistances to heat, water and fatigue as well as improved adhesion resistances, rubber tires employing such cords having an extended service life and improved performances.

It will be understood that the industrial fibrous materials which may be treated according to the present invention are not limited to rayon tire cords but also includes other industrial synthetic fibrous materials such as rayon belt duck, nylon cords and nylon duck.

It will also be understood that, though, in the examples, typically drying or semidrying oil was used for containing metal soap, any of the vegetable oils or any combination thereof may also be used.

In order to apply a dilute solution of vegetable fat or oil containing metal soap to fibrous material, various processes may be employed as stated hereinbefore; that is, the application may be effected on fibers at the spinning stage, or on yarns, cords or fabrics after spinning, or by immersing such cords or fabrics in an adhesive solution or spreading such solution thereover at the time of adhesive treatment with the dilute solution admixed to the adhesive solution. Alternatively, this may be effected after or before the adhesive treatment.

What is claimed is:

l. A method of treating a fibrous rubber reinforcing material in order to improve its physical properties, particularly its heat resistance and bonding to the rubber material, which method comprises immersing the rubber reinforcing material in a dilute solution of a vegetable oil containing a metal soap having the general formula wherein Me represents a divalent metal and n represents a positive integer between 8 and 18, drying the reinforcing material after withdrawal from the solution and then subjecting it to an adhesive treatment with a resorcinformaldehyde-resin.

2. A method as defined in claim 1 wherein the solvent for the vegetable oil is water.

3. A method as defined in claim 1 wherein the solvent for the vegetable oil is an organic solvent.

4. A method of treating a fibrous rubber reinforcing material in order to improve its physical properties, particularly its heat resistance and bonding to the rubber material, which method comprises immersing the rubber reinforcing material in a dilute solution of a vegetable oil containing a metal soap having the general formula wherein Me represents a divalent metal and n represents a positive integer between 8 and 18 so as to incorporate in the said reinforcing material a solids content obtained from said vegetable oil and metal soap in an amount of up to 5% by weight of the reinforcing material, said metal soap being applied to said fibrous material at a time distinct from the application to said fibrous material of a resorcin-formaldehyde-resin.

5. A method of treating a fibrous rubber reinforcing material in order to improve its physical properties, particularly its heat resistance and bonding to the rubber material, which method comprises immersing the reinforcing material in a mixture of a dilute solution of vegetable oil containing a metal soap having the general formula wherein Me represents a divalent metal and n represents a positive integer between 8 and 18, and a solution of a bonding agent, and drying the reinforcing material after Withdrawal from said mixture of solutions.

6. A method of making rubber products which are reinforced with an industrial fibrous material, said method comprising immersing the fibrous material in a dilute solution of a vegetable oil containing a metal soap having the general formula [CH (CH CO Me Me being a divalent metal, n being a positive integer between 8 and 18, after treating the fibrous material with a resorcin-formalin-resin, to improve the physical properties, the heat resistance and the bonding strength, of the rubber products.

7. A method of making rubber products which are reinforced with an industrial fibrous material, said method comprising immersing the fibrous material in a dilute solution of a vegetable oil containing a metal soap having the general formula wherein Me represents a divalent metal and n represents a positive integer between 8 and 18.

References Cited in the file of this patent UNITED STATES PATENTS 1,807,755 Ryley et al. June 2, 1931 2,431,078 Powell et al. Nov. 18, 1947 2,436,980 Standley et al. May 2, 1948 2,663,653 Zimmerman Dec. 22, 1953 2,673,818 Woog Mar. 30, 1954 2,869,610 Lippman et al Jan. 20, 1959

Claims

1. A METHOD OF TREATING A FIBROUS RUBBER REINFORCING MATERIAL IN ORDER TO IMPROVE ITS PHYSICAL PROPERTIES, PARTICULARLY ITS HEAT RESISTANCE AND BONDING TO THE RUBBER MATERIAL, WHICH METHOD COMPRISES IMMERSING THE RUBBER REINFORCING MATERIAL IN A DILUTE SOLUTION OF A VEGETABLE OIL CONTAINING A METAL SOAP HAVING THE GENERAL FORMULA