JP3379900B2 - Rubber processing aid, rubber composition to which it is added, and method for producing rubber composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD 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 processing aid. The present invention also relates to a method for producing a rubber composition by adding a specific rubber processing aid component to the rubber component in the step of preparing the rubber composition. The rubber processing aid of the present invention is particularly excellent in the action of dispersing silica,
By using this processing aid, it is possible to obtain a rubber composition having a low viscosity, a high vulcanization rate, and excellent processability.
The rubber composition of the present invention can be used in various applications, but in particular, it can be used as a tread or a side of a pneumatic tire for automobiles, bicycles and the like.
Further, since carbon black is not 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 a rubber composition, in order to enhance the plasticity of the rubber, promote the uniform dispersion of various auxiliaries, and improve the processability in rolling, extrusion, molding, etc. Processing aids such as agents and softeners are added. Generally, a fatty acid ester or the like is used as the plasticizer, and a higher fatty acid such as lauric acid or stearic acid and a process oil are used as the softening agent. This softening agent has an excellent effect to disperse an inorganic filler such as carbon black.

In the kneading step, plasticizers, softening agents and the like are used as processing aids, and the quality of the kneading characteristics in this step has a great influence on the physical properties and appearance of the rubber molded product. Moreover, the amount of processing aids added is usually small, and in order to obtain high-quality molded products, accurate measurement, etc.
Strict process control is required. Therefore, the processing aid is generally prepared and added by the masterbatch method, and the addition order of various additives is examined and the kneading conditions are finely adjusted according to the kneading state.

By the way, in recent years, silica has been added in order to improve the low temperature characteristics of the rubber composition. However, this silica has a strong cohesive property and is dispersed with other components of the composition such as a rubber component. Poor in compatibility and compatibility, it is not easy to disperse uniformly. Then, there is a problem that the viscosity of the rubber composition increases due to the poor dispersion due to the aggregation, and the processability decreases. Further, since the surface of silica is acidic and adsorbs a basic substance that is a vulcanization accelerator, there is a problem that vulcanization is hindered and the physical properties of the vulcanized rubber deteriorate.

[0005]

DISCLOSURE OF THE INVENTION The present invention is to solve the above-mentioned conventional problems, and is a rubber processing aid prepared by mixing a specific fatty acid and an amine, particularly an amine salt formed. An object of the present invention is to provide a processing aid consisting of and a rubber composition to which the processing aid is added. Another object of the present invention is to provide a method for producing a rubber composition by adding a specific fatty acid and an amine in the step of preparing the rubber composition and allowing them to act as a processing aid. By using the rubber processing aid of the present invention, or by the method for producing a rubber composition of the present invention, it is possible to easily disperse this silica, even when silica is blended. A rubber composition having excellent kneading properties and processability can be obtained.

[0006]

The rubber processing aid of the present invention is characterized by mixing an amine with a fatty acid obtained by hydrolyzing castor oil. Further, the rubber composition of the present invention contains a fatty acid obtained by hydrolyzing castor oil.
Ricinoleic acid and alkanol as an amine
A rubber composition containing a processing aid for rubber formed by mixing with min, wherein the processing aid for rubber is 0.5 to 5 parts by weight when the rubber is 100 parts by weight. Characterize. Furthermore, the method for producing a rubber composition of the present invention comprises adding ricinoleic acid as a fatty acid obtained by hydrolyzing castor oil and an alkanolamine as an amine to the rubber component in the step of preparing the rubber composition. Characterize.

The "castor oil" is composed of glyceride of ricinoleic acid, which is the main component, and glycerides of oleic acid, linoleic acid, palmitic acid and stearic acid. By hydrolyzing these glycerides,
Ricinoleic acid, which is a hydroxy acid, and other fatty acids are obtained. As the above-mentioned "fatty acid", "ricinoleic acid" which is a hydroxy acid is preferable because it has an excellent effect of improving the kneading property. Further, a hydroxy acid obtained by introducing a hydroxyl group into linoleic acid, palmitic acid and stearic acid can be used as well.

As the above-mentioned "amine", various ones such as alkylamine and alkanolamine can be used, but those capable of forming an "amine salt" with a fatty acid are preferable. Further, it is preferable to use “monoamine”, and particularly preferable is a primary monoamine which easily forms a salt. As long as this primary monoamine is used, even an amine having a relatively long-chain alkyl group can be used, but those having a short-chain alkyl group such as methylamine, ethylamine, propylamine, and butylamine can be used. More preferable. Further, although it is difficult to form a salt, it has a secondary amine such as dimethylamine, diethylamine, dipropylamine and dibutylamine, a tertiary amine such as tritimeramine and triethylamine, etc., and particularly has a short chain alkyl group. If it is a monoamine, even a secondary amine or a tertiary amine can be used.

As the amine, it is preferable to use "alkanolamine". When the amine having a hydroxyl group is used, the kneading properties and processability of the rubber composition are further improved. As this alkanolamine, those having a short-chain alkyl group are preferable, and "mono,
"Di and triethanolamine" are particularly preferred. As the alkanolamine, N-methylethanolamine,
It is also possible to use monoamines such as N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanolamine and dimethylethanolamine, and diamines such as aminoethylethanolamine. In addition, it is also possible to use mono-, di- and triisopropanolamines.

The fatty acid and the amine are mixed in an appropriate amount ratio,
Although it can be used as a processing aid, in particular, when the amine is an alkanolamine, 1 mol of fatty acid,
It is preferable that the amine is “0.5 to 2 mol”. When the amount of amine, especially alkanolamine such as ethanolamine, is less than 0.5 mol, fatty acid having strong acidity becomes excessive, and the processing aid itself becomes strongly acidic and vulcanization is inhibited, which is not preferable. . On the other hand, when the amount of ethanolamine or the like exceeds 2 mols, the action of accelerating vulcanization by this amine becomes strong, and the normal vulcanization reaction may be impaired. The amount ratio of this amine is particularly 0.7 to 1.7 mol, and more preferably 0.1 to 1 mol of the fatty acid and its derivative.
It is preferably 8 to 1.3 mol. When the amine in the amount ratio within this range is used, the kneading characteristics and processability of the rubber composition are sufficiently improved and the vulcanization reaction is not impaired.

A mixture of a fatty acid and an amine, especially
The processing aid for rubber that has become an amine salt contains 100 parts of rubber component.
It is preferable to add "0.5 to 5 parts by weight" when the amount is parts by weight. If the blending amount of the processing aid is less than 0.5 part by weight, the twist property and the workability may not be sufficiently improved. On the other hand, if it is blended in a large amount in excess of 5 parts by weight, the tackiness tends to increase and the processability tends to decrease. The blending amount is particularly preferably 1 to 4 parts by weight, more preferably 1.5 to 3 parts by weight. When the amount is in this range, the rubber composition can be more reliably improved in the twist property and processability, and the rubber composition having excellent performance of the present invention can be easily obtained.

Many of the rubber processing aids prepared by mixing the fatty acid of the present invention with an amine, especially an alkanolamine, have a relatively high melting point and solidify at about 0 ° C. Therefore, even in a cold region or a warm region, it may be hardened and hardened in winter. Therefore, it is preferable that the fatty acid or the like and the amine are mixed with a porous material so that the amine salt of the fatty acid or the like is adsorbed to the porous material and used as a powder. As described above, the powder can be used regardless of the ambient temperature.

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

A mixture of a fatty acid and an amine, in particular, the amount ratio of an amine salt of a fatty acid and a porous material such as silica is 100% by weight of the amine salt of a fatty acid. Is preferably 20 to 80 parts by weight. When the amount of the porous body is less than 20 parts by weight, a considerable portion of the fatty acid amine salt 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 amount of the porous body is 80 parts by weight, all of the fatty acid amine salt and the like are adsorbed to the porous body, and the fatty acid amine salt and the like do not remain unadsorbed. The amount ratio of the porous body is particularly preferably 30 to 70 parts by weight, further preferably 40 to 60 parts by weight. If the amount ratio of the porous body is within this range, the entire amount of the fatty acid amine salt and the like is surely adsorbed to the porous body,
The processing aid can be a powder. As the silica, those commonly 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 aid in the processing of 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 for tire treads and the like, and these rubbers may be used alone or in combination of two or more. May be. As the rubber component, 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 product such as a tire having excellent wear resistance can be obtained by such combination.

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

The rubber processing aids of the present invention are 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 other compounding agents such as silica and carbon black and added together with them to the rubber component. Further, in the kneading step of preparing the rubber composition, the fatty acid or amine which is a component of the processing aid can be added simultaneously or separately. This processing aid facilitates addition and kneading of various aids such as silica, carbon black or a softening agent to the rubber component, and silica or the like is rapidly and uniformly dispersed in the rubber component. Therefore, the time required for kneading and dispersing the rubber composition is shortened, and deterioration of physical properties due to long-term kneading is suppressed. Further, since the dispersion of silica and the like is good, the reinforcing effect and the like are increased, and the abrasion resistance and durability of the vulcanized rubber are sufficiently improved.

In the rubber composition, the amount of silica generally used for the purpose of improving the physical properties of the vulcanized rubber is 10 to 80 when the rubber component is 100 parts by weight.
It is preferable to use parts by weight. If the amount of this silica is less than 10 parts by weight, the abrasion resistance of the vulcanized rubber may decrease, especially when the amount of a processing aid such as an amine salt of a fatty acid added is small. Further, the Mooney viscosity of the rubber composition is low, and the kneading property is not sufficiently improved. On the other hand, when the blending 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 blended is particularly preferably 30 to 80 parts by weight. When the blending amount is within this range, a rubber composition having more excellent kneading properties and processability can be obtained, and the vulcanized rubber also has sufficiently improved abrasion resistance and the like.

The carbon black blended for the purpose of reinforcing the vulcanized rubber preferably has a blending amount of 200 parts by weight or less when the rubber component is 100 parts by weight. This blending amount is particularly 150 parts by weight or less, and further 1
It is preferable that the amount is 00 parts by weight or less. If the amount of carbon black exceeds 200 parts by weight, the kneading characteristics and processability of the rubber composition will deteriorate, and the vulcanized rubber will tend to be hard and brittle, such as a decrease in elongation at break. It is also possible to use silica and carbon black in combination, in which case 20 to 50 parts by weight of silica and 30 to 50 carbon black are used.
It is preferable that the weight part and the total amount thereof be 50 to 100 parts by weight. When the compounding amounts of silica and carbon black are within this range, a rubber composition having excellent kneading properties and processability can be obtained, and the strength and abrasion resistance 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 agent, a vulcanizing agent such as sulfur, a vulcanization accelerator such as aldehyde-amines and guanidines, a vulcanization accelerator auxiliary such as zinc white, stearic acid and the like can be used. In addition, anti-aging agents such as amines and phenols, softening agents such as process oils, tackifiers, plasticizers and the like can be used. The amount of these auxiliaries added may be a level usually used.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to Examples. 1) Used rubber component and auxiliary agent NR (natural rubber); SMR CV60 processing aid for rubber; triethanolammonium lysylate (product of the present invention) ricinoleic acid butyl ester (conventional product) silica; manufactured by Degussa, trade name " Ultrasil VN3 "carbon black; Showa Cabot Co., Ltd., trade name" N-220 "The quantitative ratio of each component except NR is as shown in Table 1. Table 1
Represents the parts by weight when NR is 100 parts by weight.

2) Other auxiliaries and addition amount Stearic acid; manufactured by Shin Nippon Rika Co., Ltd., trade name "50"
s ", 1 part by weight process oil; manufactured by Fuji Kosan Co., Ltd., trade name" Fuccol # 3 ", 10 parts by weight vulcanization accelerator; manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name" NOXCELLER NS ", 1.2 Parts by weight: Tsurumi Chemical Co., Ltd., trade name "Sulfax 200S", 2 parts by weight

3) Method for preparing rubber composition NR, which is a rubber component, was kneaded by a twin-screw kneader having a capacity of 3 liters for 1 minute under the conditions of a rotor rotation speed of 500 rpm and a temperature of 100 ° C. Then, a predetermined amount of triethanol ammonium lysylate, etc., and at least one of silica and carbon black, and other additives other than sulfur as a vulcanizing agent and a vulcanization accelerator are blended,
The mixture was kneaded for another 5 minutes. Next, sulfur and a vulcanization accelerator were added to this kneaded product, and the mixture was kneaded at 50 ° C. for 5 minutes with 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, the Mooney viscosity at the time of kneading and the tc90 of the vulcanized rubber were measured.
And the dispersity were measured. The results are also shown in Table 1.

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

(1) Combination of triethanolammonium lysylate and at least one of silica and carbon black As shown in Table 1, triethanolammonium lysylate which is a processing aid for rubber of the present invention and conventional ones are used. The performance of the ester as an auxiliary agent as a processing auxiliary agent was compared. Further, silica and carbon black were similarly compared and evaluated.

[0026]

[Table 1]

According to the results of Table 1, in Experimental Example 2 in which ricinoleic acid butyl ester was added, the Mooney viscosity was lower than in Experimental Example 1 in which ricinoleic acid butyl ester was not added, and tc9
0 and the dispersity are also slightly improved. As described above, it is understood that the conventional processing aid ester also has an effect of improving the processability. However, in Experimental Example 7 in which triethanolammonium lysylate was added instead of the ester in Experimental Examples 1 and 2, Mooney viscosity, tc90, and dispersity were all significantly improved as compared with Experimental Example 2, It is clear that the processing aid of the present invention improves the processability. This is a comparison between Experimental Examples 3 and 4 in which silica and carbon black are used in combination with Experimental Example 8, and Experimental Examples 5 and 6 in which silica is used, and Experimental Example 9.
The same is also true in comparison with the above, which confirms the excellent performance of the processing aid of the present invention.

In particular, at tc90 and dispersity, the effect of lysylate, which is the processing aid of the present invention, is great, and even more significant effect is obtained when silica is used as the porous body. That is, according to Experimental Examples 1 to 9, as is conventionally said, the workability and dispersibility of silica and carbon black are lowered when silica is generally mixed. However, this is improved by the addition of ester or lysylate, and
As is clear from FIG. 1, in the lysylate which is the processing aid of the present invention, the dispersity is greatly improved. In particular, it is understood that the effect is great when silica is used, and that the processing aid of the present invention is very useful in a rubber composition containing silica, which has not been easily dispersed in rubber conventionally.

Incidentally, in FIG. 1, the improvement rate means 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, respectively, from the numerical values of the improved dispersity to those before the improvement. It is the value obtained by subtracting the value of the degree of dispersion, dividing it by the value of the degree of dispersion before improvement, and multiplying by 100.

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

[0031]

[Table 2]

According to the results shown in Table 2, in Experimental Example 10 in which the amount ratio of fatty acid was high, vulcanization was inhibited and tc90 was lengthened. On the other hand, in Experimental Example 13 in which the amount ratio of amine was high, the vulcanization was promoted, but the dispersity was reduced. As described above, tc90 and polydispersity tend to contradict each other depending on the amount ratio of fatty acid and amine. Considering the balance of each characteristic, 0.5 to 2 mol of amine is used for 1 mol of fatty acid. It can be seen that a processing aid having more preferable performance can be obtained in the case of doing.

[0033]

EFFECTS OF THE INVENTION According to the rubber processing aid of the present invention, particularly in the case of a rubber composition containing silica, the processability,
A rubber composition having excellent dispersibility can be obtained. In particular,
By using a specific fatty acid and a specific amine, a rubber processing aid with better performance can be obtained. Further, by adsorbing the processing aid on a porous body such as silica, it is possible to obtain a processing aid having further excellent performance.

Furthermore, according to the method for producing a rubber composition of the present invention, by adding a specific fatty acid and a specific amine to the rubber component in the preparation step, the processability and dispersibility are easily improved. It is possible to produce a rubber composition.

[Brief description of drawings]

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

Continuation of front page (51) Int.Cl. ⁷ Identification code FI // (C08K 5/00 C08K 5:09 5:09 5:17 5:17) C08K 7:26 (C08K 7/22 7:26 5: 09 5:17) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 21/00 B60C 1/00 C08K 7/22-7/26 C08K 5/09-5/098 C08K 5/16- 5/18

Claims (13)

(57) [Claims] 1. A rubber processing aid comprising a mixture of a fatty acid obtained by hydrolyzing castor oil and an amine. 2. The rubber processing aid according to claim 1, wherein the fatty acid 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. 4. The method of claim 1, wherein the amine is a monoamine.
4. The rubber processing aid according to any one of 1 to 3. 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 rubber processing aid according to claim 1, wherein the amine is 0.5 to 2 mol per 1 mol of the fatty acid. 8. The rubber processing aid according to any one of claims 1 to 7, which is formed by mixing a porous body. 9. The rubber processing aid according to claim 8, wherein the porous body is silica. 10. A fat obtained by hydrolyzing castor oil.
Ricinoleic acid as acid and alkano as amine
A rubber composition containing a rubber processing aid mixed with luamine , wherein the rubber processing aid is 0.5 to 5 parts by weight when the rubber component is 100 parts by weight. A rubber composition comprising: 11. In the step of preparing a rubber composition,
The rubber component, fatty acid obtained by hydrolyzing castor oil and
Ricinoleic acid and alkanol as amine
A method for producing a rubber composition, which comprises adding min . 12. The method for producing a rubber composition according to claim 11, wherein a porous body is added in the preparing step. 13. The porous body is silica.
13. The method for producing the rubber composition according to 1 or 12.