JPH11293040A - Processing aid for rubber, rubber composition produced by adding the same, and production of rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing aid for a rubber useful in improving milling characteristics and processability, especially of a silica-loaded rubber composition, a rubber composition produced by adding the processing aid and a method for producing the rubber composition by adding a specified processing aid component. SOLUTION: A processing aid for a rubber is obtained by mixing a fatty acid obtained by hydrolyzing a castor oil and its derivative with an amine. As a derivative of the fatty acid, a ricinoleic acid that is the main component of the castor oil and a hydroxy acid is preferably used. As an amine, one capable of forming an amine salt with the fatty acid or the like can be used and especially, a primary monoamine is preferable. The processing aid can be used as a powder by adsorbing it onto a porous material, especially silica. A powder, if it is used at a low temperature in winter or the like, is free from solidification and is easily handled. The processing aid can be used by adding it to a variety of rubber components such as a natural rubber and a styrene-butadiene rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber processing aid useful for improving the kneading characteristics and processability of a rubber composition containing silica, and a rubber composition containing the same. The present invention also relates to a method for producing a rubber composition by adding a specific rubber processing aid component to a rubber component in a rubber composition preparation step. The rubber processing aid of the present invention is particularly excellent in dispersing silica,
If this processing aid is used, a rubber composition having a low viscosity, a high vulcanization rate, and excellent processability can be obtained.
The rubber composition of the present invention can be used in various applications, and in particular, can be used as a tread, a side, and the like of a pneumatic tire such as an automobile and a bicycle.
Further, since carbon black is not used as an essential compounding agent, a rubber molded product having a desired color tone other than black can be obtained.

[0002]

2. Description of the Related Art In the preparation of rubber compositions, in order to increase the plasticity of rubber, promote uniform dispersion of various auxiliaries, and improve the workability of rolling, extrusion, molding, etc., plasticization is performed in a kneading step. Processing aids such as agents and softeners are added. Generally, fatty acid esters and the like are used as plasticizers, and higher fatty acids such as lauric acid and stearic acid and process oils are used as softeners. This softener has an excellent action of dispersing an inorganic filler such as carbon black.

[0003] In the kneading step, a plasticizer, a softening agent and the like are used as processing aids, but the quality of the kneading property in this step has a great influence on the physical properties, appearance and the like of the rubber molded product. In addition, usually, the amount of the processing aid added is small, and in order to obtain a high-quality molded product, accurate measurement and the like are required.
Strict process control is required. Therefore, the processing aid is generally prepared and added by a master batch method, and the addition order of various additives is examined, and the kneading conditions are finely adjusted according to the kneading state.

In recent years, silica has been added in order to improve the low-temperature properties of rubber compositions. However, this silica has a strong cohesive property and is dispersed with other components of the composition such as a rubber component. It is inferior in compatibility and compatibility, and it is not easy to disperse uniformly. In addition, there is a problem that the viscosity of the rubber composition increases due to poor dispersion due to the aggregation, and the processability decreases. In addition, since the surface of silica is acidic and adsorbs a basic substance as a vulcanization accelerator, vulcanization is inhibited, and there is a problem that the physical properties of the vulcanized rubber are reduced.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a processing aid for rubber obtained by mixing a specific fatty acid or a derivative thereof with an amine, especially a rubber-based processing aid. It is an object of the present invention to provide a processing aid comprising an amine salt and a rubber composition to which the processing aid is added. Also,
An object of the present invention is to provide a method for producing a rubber composition by adding a specific fatty acid or a derivative thereof and an amine in a step of preparing a rubber composition and acting as a processing aid. If the processing aid for rubber of the present invention is used, or according to the method for producing a rubber composition of the present invention, in particular, even when silica is blended, the silica can be easily dispersed. And a rubber composition having excellent kneading properties and processability can be obtained.

[0006]

The rubber processing aid of the first invention is characterized by mixing a fatty acid and its derivative obtained by hydrolyzing castor oil with an amine.
A rubber composition according to a tenth aspect of the present invention is a rubber composition containing the rubber processing aid according to any one of claims 1 to 9, wherein the rubber is 100 parts by weight. ,
The rubber processing aid is 0.5 to 5 parts by weight. Further, in the method for producing a rubber composition according to the eleventh invention, in the step of preparing the rubber composition,
A fatty acid and a derivative thereof obtained by hydrolyzing castor oil, and an amine are added.

The above "castor oil" is composed of glycerides of oleic acid, linoleic acid, palmitic acid and stearic acid, in addition to glycerides of ricinoleic acid, which is the main component. By hydrolyzing these glycerides,
Ricinoleic acid, which is a hydroxy acid, and other fatty acids are obtained. As the above “fatty acids and derivatives thereof”,
As in the second invention, "ricinoleic acid", which is a hydroxy acid, is preferable because of its excellent effect of improving kneading properties. Further, a hydroxy acid obtained by introducing a hydroxyl group into linoleic acid, palmitic acid and stearic acid can also be used.

As the above-mentioned "amine", various ones such as an alkylamine and an alkanolamine can be used, but those which can form an "amine salt" with a fatty acid and its derivative as in the third invention are preferable. Further, as in the fourth invention, it is preferable to use a “monoamine”, and a primary monoamine which easily forms a salt is particularly preferable. As long as the primary monoamine is an amine having a relatively long chain alkyl group, an amine having a short chain alkyl group such as methylamine, ethylamine, propylamine and butylamine can be used. More preferred. Further, although salts are difficult to form, secondary amines such as dimethylamine, diethylamine, dipropylamine and dibutylamine, tertiary amines such as trithymamine and triethylamine, and particularly, have a short-chain alkyl group As long as it is a monoamine, a secondary amine or a tertiary amine can be used.

As the amine, it is preferable to use "alkanolamine" as in the fifth invention.
The use of the amine having a hydroxyl group further improves the kneading characteristics and processability of the rubber composition. As this alkanolamine, those having a short-chain alkyl group are preferable, and as in the sixth invention, "mono, di and triethanolamine" are particularly preferable. Examples of the alkanolamine include monoamines such as N-methylethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanolamine and dimethylethanolamine, and diamines such as aminoethylethanolamine. Etc. can also be used.
In addition, mono, di and triisopropanolamine can also be used.

The fatty acid and its derivative and the amine can be mixed at an appropriate ratio to obtain a processing aid.
When the amine is an alkanolamine, as in the seventh invention, it is preferable to set the amine to "0.5 to 2 mol" with respect to 1 mol of the fatty acid and its derivative. When the amount of amine, particularly alkanolamine such as ethanolamine, is less than 0.5 mol, fatty acid having strong acidity becomes excessive, and the processing aid itself becomes strong acid and vulcanization is inhibited, which is not preferable. . On the other hand, when the amount of ethanolamine or the like exceeds 2 mol, the effect of accelerating vulcanization by this amine becomes strong, and the normal vulcanization reaction may be impaired. The amount ratio of this amine is determined by the fatty acid and its derivative 1
In particular, 0.7 to 1.7 mol, more preferably 0.8 mol,
It is preferable to set it to 1.3 mol. When the amine having a ratio in this range is used, the kneading properties and processability of the rubber composition are sufficiently improved, and the vulcanization reaction is not impaired.

The rubber processing aid obtained by mixing a fatty acid or a derivative thereof with an amine, particularly in the form of an amine salt, has a value of “0” when the rubber component is 100 parts by weight as in the tenth invention. 0.5-5 parts by weight ". If the amount of the processing aid is less than 0.5 part by weight, the torsion characteristics and processability may not be sufficiently improved. On the other hand, if the amount is more than 5 parts by weight, the tackiness tends to increase, and the workability tends to decrease. This compounding amount is, in particular, 1 to 4
Parts by weight, and more preferably 1.5 to 3 parts by weight. With the compounding amount in this range, the torsion characteristics and processability of the rubber composition can be more reliably improved, and
The rubber composition of the present invention having excellent performance can be easily obtained.

The rubber processing aid obtained by mixing the fatty acid and its derivative of the present invention with an amine, especially an alkanolamine, has a relatively high melting point and often solidifies at about 0 ° C. For this reason, even in a cold region or a warm region, it may be hardened in the winter and difficult to handle. Therefore, as in the eighth invention, the fatty acid and the amine are
Further, it is preferable that the porous body is mixed and the amine salt of a fatty acid or the like is adsorbed on the porous body and used as a powder. Thus, if it is a powder, it can work regardless of environmental temperature.

As the above "porous material", silica, alumina, magnesium oxide, titanium oxide, zirconium oxide, carbon black, zeolite and the like can be used. As this porous body, as in the ninth invention, “silica” which does not affect other auxiliaries such as a vulcanizing agent and can easily prepare a masterbatch together with other auxiliaries is used. Is preferred. Particularly, the particle size is 5 to 1
And the oil absorption is 100 to 300 cc / 100.
g (1-3 cc / g), and silica having a BET surface area of 10-600 m ² / g is more preferable.
Further, carbon black, which is often blended for the purpose of reinforcing vulcanized rubber, is also preferable, and a combination of these silica and carbon black is also useful.

A mixture of a fatty acid or the like and an amine, in particular, the ratio of the amine salt of the fatty acid or the like to the porous body such as silica is such that when the amine salt or the like of the fatty acid is 100 parts by weight, Is preferably 20 to 80 parts by weight. If the amount of the porous body is less than 20 parts by weight, a considerable portion of the amine salt of the fatty acid or the like remains without being adsorbed, and the processing aid solidifies at a low temperature, which is not preferable. On the other hand, when the porous body is 80 parts by weight, all of the fatty acid amine salt and the like are adsorbed on the porous body, and the fatty acid amine salt and the like do not remain without being adsorbed. The amount ratio of the porous body is preferably 30 to 70 parts by weight, more preferably 40 to 60 parts by weight. If the ratio of the amount of the porous body is within this range, the entire amount of the amine salt of the fatty acid or the like is surely adsorbed on the porous body,
The processing aid can be a powder. As the silica, those generally used in rubber compositions for tire treads and the like can be used as they are.

The rubber processing aid of the present invention can be used as an auxiliary in processing various rubbers. Examples of the rubber component include various synthetic rubbers such as natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), and styrene-butadiene rubber (SBR). These rubbers are generally used in the compounding of rubber compositions conventionally used in tire treads and the like, and these rubbers may be used alone or in combination of two or more. You may. As the rubber component, in particular, at least one of NR and IR, and B
It is preferable to use at least one of R and SBR together, and a rubber molded article such as a tire having excellent wear resistance and the like can be obtained by such combination.

The ratio of the amounts of NR and IR to BR and SBR is not particularly limited. When the total amount of these rubbers is 100 parts by weight, the NR and IR are 20 to 60 parts by weight, BR is
And SBR is preferably 80 to 40 parts by weight.
This ratio is such that the NR and IR are 25 to 55 parts by weight, in particular 3
5 to 45 parts by weight, 75 to 45 parts by weight of BR and SBR,
In particular, the content is more preferably 65 to 55 parts by weight. When such a rubber component is used, a molded article having excellent abrasion resistance, durability and the like can be obtained, particularly when used as a tire tread or the like. It should be noted that other rubbers can be used in combination with this rubber component in a quantitative ratio that does not impair the kneading characteristics, processability, etc. of the rubber composition, and the abrasion resistance, etc. of the vulcanized rubber.

The rubber processing aid of the present invention comprises NR, IR,
It is useful as a processing aid for rubber components used in tires such as BR and SBR. This processing aid may be added to the rubber component in advance, or may be added to another compounding agent such as silica or carbon black, and may be added to the rubber component together therewith. Further, as in the eleventh invention, in the kneading step of preparing the rubber composition, fatty acids and derivatives thereof, or amines, which are components of the processing aid, can be added simultaneously or separately. By this processing aid, silica, carbon black or softener, etc.
Addition and kneading of various auxiliaries to the rubber component become easy, and silica and the like are rapidly and uniformly dispersed in the rubber component. Therefore, the time required for kneading and dispersing the rubber composition is reduced,
A decrease in physical properties due to prolonged kneading can be suppressed. Further, since the dispersion of silica and the like is good, the reinforcing effect and the like are increased, and the wear resistance and durability of the vulcanized rubber are sufficiently improved.

In the rubber composition, silica is generally used for the purpose of improving the physical properties of the vulcanized rubber in an amount of 10 to 80 when the rubber component is 100 parts by weight.
It is preferable to use parts by weight. If this silica is less than 10 parts by weight, the abrasion resistance of the vulcanized rubber may decrease, especially when the amount of processing aids such as amine salts of fatty acids is small. Further, the Mooney viscosity of the rubber composition is low, and the kneading characteristics are not sufficiently improved. On the other hand, if the amount exceeds 80 parts by weight, the Mooney viscosity becomes too high, and sufficient rubber properties and kneading properties cannot be obtained. The amount of silica is particularly preferably 30 to 80 parts by weight. When the amount is within this range, a rubber composition having more excellent kneading characteristics and processability can be obtained, and the abrasion resistance and the like of the vulcanized rubber can be sufficiently improved.

The amount of the carbon black compounded for the purpose of reinforcing the vulcanized rubber is preferably 200 parts by weight or less when the rubber component is 100 parts by weight. This compounding amount is preferably 150 parts by weight or less, and more preferably 1 part by weight.
It is preferably not more than 00 parts by weight. When the carbon black content exceeds 200 parts by weight, the vulcanized rubber tends to be hard and brittle, for example, the kneading properties and processability of the rubber composition are reduced, and the elongation at break is reduced. In addition, silica and carbon black can be used in combination. In this case, silica is used in an amount of 20 to 50 parts by weight, and carbon black is used in an amount of 30 to 50 parts.
It is preferable that the total amount thereof be 50 to 100 parts by weight. When the compounding amount of silica and carbon black is in this range, a rubber composition having excellent kneading characteristics and processability can be obtained, and the strength, wear resistance and the like of the obtained vulcanized rubber can be sufficiently improved.

Further, in the rubber composition of the present invention, other auxiliaries generally used in this type of rubber composition can be appropriately used. As such an auxiliary, a vulcanization accelerator such as sulfur, a vulcanization accelerator such as aldehyde-amines and guanidines, and a vulcanization accelerator such as zinc white and stearic acid can be used. In addition, an antioxidant such as amines and phenols, a softening agent such as process oil, and the like, a tackifier, a plasticizer, and the like can be used. The addition amount of these auxiliaries can be set to a level usually used.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples. 1) Rubber Component and Auxiliary Used NR (Natural Rubber); SMR CV60 Rubber Processing Aid; Triethanolammonium Resilate (Product of the Present Invention) Ricinoleic Acid Butyl Ester (Conventional Product) Silica; Ultrasil VN3 "carbon black; manufactured by Showa Cabot Co., Ltd., trade name" N-220 "The ratio of each component except NR is as shown in Table 1. Table 1
Are parts by weight when NR is 100 parts by weight.

2) Other auxiliaries and amounts added Stearic acid; trade name "50" manufactured by Shin Nippon Rika Co., Ltd.
s ", 1 part by weight process oil; manufactured by Fujikosan Co., Ltd., trade name" Fucor # 3 ", 10 parts by weight vulcanization accelerator; Ouchi Shinko Chemical Industry Co., Ltd .; trade name" Noxeller NS ", 1.2 Parts by weight Sulfur; Tsurumi Chemical Co., Ltd., trade name "Sulfax 200S", 2 parts by weight

3) Method for Preparing Rubber Composition NR as a rubber component was kneaded for 1 minute at a rotor rotation speed of 500 rpm and a temperature of 100 ° C. using a 3-liter capacity twin-screw kneader. Thereafter, a predetermined amount of triethanolammonium resylate and the like, and at least one of silica and carbon black, and other auxiliary agents except sulfur and a vulcanization accelerator as a vulcanizing agent are blended,
Kneading was continued for another 5 minutes. Next, sulfur and a vulcanization accelerator were added to the kneaded product, and the mixture was kneaded at 50 ° C. for 5 minutes by a kneading roll composed of a pair of 8-inch rolls having a gap of 4 mm to prepare a rubber composition. Then, using this rubber composition, Mooney viscosity during kneading and tc90 of the vulcanized rubber were determined.
And the degree of dispersion. The results are also shown in Table 1.

4) Test method Mooney viscosity: JIS K 6300 (rotor type: L, preheating time: 1 minute, rotor operating time: 4 minutes,
(Test temperature; 125 ° C.) tc90: Use a viscometer in accordance with JIS K 6300 (amplitude angle: 1 °, test temperature: 160 ° C.), observe the increase in viscosity in the vulcanization curve over time, and adjust the viscosity to the upper limit. The time when 90% is reached is read. As this time is shorter, the torque applied to the kneading machine is reduced in a shorter time, and processing can be performed in a shorter time, and so-called workability with a good start can be obtained. Dispersion degree: 10 × 15 × 50 which was vulcanized at 160 ° C. for 20 minutes using a dispersometer according to ISO / DIN1345.
mm of the vulcanized sheet. The surface area per unit volume of the dispersion is measured. The larger the value, the better the dispersibility.

(1) Combination of triethanolammonium resylate and at least one of silica and carbon black As shown in Table 1, triethanolammonium resylate, a processing aid for rubber of the present invention, and conventional The performance of the ester as a processing aid as a processing aid was compared. Further, silica and carbon black were similarly compared and evaluated.

[0026]

[Table 1]

According to the results in Table 1, the Mooney viscosity was lower in Experimental Example 2 in which butyl ricinoleate was added than in Experimental Example 1 in which butyl ricinoleate was not added, and tc9
0 and the degree of dispersion are also slightly improved. Thus, it can be seen that the ester, which is a conventional processing aid, also has the effect of improving processability. However, in Experimental Example 7 in which triethanolammonium lysylate was added instead of the ester in Experimental Examples 1 and 2, all of the Mooney viscosity, tc90, and dispersity were significantly improved as compared to Experimental Example 2. The improvement in workability by the processing aid of the present invention is apparent. This indicates that Experimental Examples 3 and 4 using silica and carbon black in combination and Experimental Example 8, and Experimental Examples 5 and 6 using silica and Experimental Example 9
This is exactly the same in comparison with the above, and the excellent performance of the processing aid of the present invention is supported.

In particular, with respect to tc90 and the degree of dispersion, the effect of resilate, which is a processing aid of the present invention, is large. Further, when silica is used as the porous material, a greater effect is obtained. That is, according to Experimental Examples 1 to 9, the workability and dispersibility of silica and carbon black are reduced as a whole, when silica is blended, as conventionally known. However, this has been improved by the addition of esters or lysates, and
As is evident from FIG. 1, the resiliency, which is the processing aid of the present invention, has a much higher degree of dispersion. In particular, the effect is large when silica is used, and it is understood that the processing aid of the present invention is very useful in a rubber composition containing silica, which has heretofore not been easily dispersed in rubber.

In FIG. 1, the improvement rate refers to the experimental example 1.
And Experimental Example 2 or Experimental Example 7, Experimental Example 3 and Experimental Example 4 or Experimental Example 8, and Experimental Example 5 and Experimental Example 6 or Experimental Example 9. This is a value obtained by subtracting the numerical value of the degree of dispersion and dividing it by the numerical value of the degree of dispersion before the improvement, and multiplying by 100.

(2) Examination of the molar ratio between fatty acid and amine In Experimental Example 8 in Table 1, the molar ratio between ricinoleic acid and triethanolamine was changed, and the performance as a processing aid was evaluated.

[0031]

[Table 2]

According to the results shown in Table 2, in Experimental Example 10 in which the ratio of fatty acids was high, vulcanization was inhibited and tc90 was increased. On the other hand, in Experimental Example 13 in which the amine ratio was high, vulcanization was promoted, but the degree of dispersion was low. As described above, tc90 and the degree of dispersion tend to be contradictory depending on the amount ratio of the fatty acid to the amine, and in consideration of the balance of each property, 0.5 to 2 mol of amine is used for 1 mol of fatty acid. In this case, it is found that a processing aid having more preferable performance can be obtained.

[0033]

According to the rubber processing aid of the first invention, the rubber composition having excellent processability and dispersibility as described in the tenth invention, even if the rubber composition contains silica in particular. Can be obtained. In particular, by using the specific fatty acid derivative of the second invention and the specific amine of the third to sixth inventions, a processing aid for rubber having more excellent performance can be obtained. Further, as in the eighth and ninth inventions, by adsorbing the processing aid to a porous body such as silica, the processing aid can be further improved in performance.

Further, according to the method for producing a rubber composition of the eleventh invention, in the preparation step, a specific fatty acid and a derivative thereof and an amine are added to the rubber component to easily process and disperse the rubber. The rubber composition excellent in the above can be produced.

[Brief description of the drawings]

FIG. 1 is a graph showing that the rubber processing aid of the present invention has superior performance, in particular, in a rubber composition containing silica, as compared with a conventional rubber composition.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // (C08K 5/00 5:09 5:17) (C08K 13/04 7:26 5:09 5:17)

Claims (14)

[Claims] 1. A rubber processing aid comprising a mixture of a fatty acid and a derivative thereof obtained by hydrolyzing castor oil and an amine. 2. The rubber processing aid according to claim 1, wherein the derivative is ricinoleic acid. 3. The rubber processing aid according to claim 1, wherein the amine is capable of forming a salt with the fatty acid and the derivative. 4. The method of claim 1, wherein said amine is a monoamine.
4. The processing aid for rubber according to any one of the above-mentioned items. 5. The rubber processing aid according to claim 1, wherein the amine is an alkanolamine. 6. The rubber processing aid according to claim 5, wherein the alkanolamine is at least one of monoethanolamine, diethanolamine and triethanolamine. 7. The amine according to claim 1, wherein said amine is 0.5 to 2 mol per 1 mol of said fatty acid and said derivative.
The processing aid for rubber according to any one of the above. 8. The rubber processing aid according to claim 1, which is obtained by mixing a porous body. 9. The rubber processing aid according to claim 8, wherein the porous body is silica. 10. A rubber composition containing the processing aid for rubber according to claim 1, wherein the rubber component is 100 parts by weight, and the rubber processing aid is a rubber composition. A rubber composition characterized in that the auxiliary agent is 0.5 to 5 parts by weight. 11. In the step of preparing a rubber composition,
A method for producing a rubber composition, comprising adding a fatty acid and its derivative obtained by hydrolyzing castor oil and an amine to a rubber component. 12. The method according to claim 11, wherein the derivative is ricinoleic acid, and the amine is an alkanolamine. 13. The method for producing a rubber composition according to claim 11, wherein a porous body is blended in the preparation step. 14. The method according to claim 1, wherein the porous body is silica.
14. The method for producing the rubber composition according to any one of 1 to 13.