KR102460329B1 - Rubber composition for tire and method for manufacturing the same - Google Patents

Abstract

Disclosed are a rubber composition for a tire in which modulus performance is improved by adding zinc glycerolate as a vulcanization accelerator, and a method for manufacturing the same.
The rubber composition for a tire according to the present invention includes raw rubber, carbon black, and a vulcanization accelerator, and the vulcanization accelerator contains zinc glycerolate.

Description

Rubber composition for tires and manufacturing method thereof

The present invention relates to a rubber composition for a tire having an effect of improving modulus, including zinc glycerolate as a vulcanization accelerator, and a method for manufacturing the same.

Recently, with the rapid spread of electric vehicles, eco-friendly elements of automobiles have been highlighted. As environmental regulations related to existing internal combustion engine vehicles are getting higher and the importance of wear resistance performance of tires continues to increase, tires with excellent wear resistance performance have been developed in line with the characteristics of electric vehicles, which have a heavier body weight compared to internal combustion engine vehicles. It is a situation in need of development.

Since the improvement of the abrasion resistance performance of automobile tires is greatly affected by the modulus properties applied to the tires, it is necessary to develop a rubber composition for tires suitable for this purpose. For example, the wear resistance properties of a tire tread are determined by the nature of the tread surface layer in contact with the ground. As the degree of wear caused by vibration and friction forces that inevitably follow during driving is reduced, the generation of fine particles in the vehicle and the lifespan of the tire tread can be increased.

Carbon black having a small particle size is used in a rubber composition for forming such a tire tread to increase reinforcing properties and improve abrasion resistance. When carbon black having a small particle size is used as a filler, carbon black having a large diameter is generally used because dispersibility of carbon black in the rubber composition is not good, or a relatively small amount of carbon black in the rubber composition is used. However, in this case, there is a problem that the wear resistance of the tire tread is not sufficient.

In order to solve this problem, there is a need to develop a tire rubber composition for improving the modulus performance of the tire.

An object of the present invention is to provide a rubber composition for a tire in which zinc glycerolate as a vulcanization accelerator is added to a rubber composition using carbon black as a filler to improve abrasion resistance.

Another object of the present invention is to provide a rubber composition for a tire having superior modulus properties compared to a rubber composition using a conventional vulcanization accelerator by mixing raw rubber and carbon black to increase the crosslinking density.

It is also an object of the present invention to provide a method for producing a rubber composition for a tire.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the examples of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the appended claims.

The rubber composition for a tire according to the present invention includes raw rubber, carbon black, and a vulcanization accelerator, and the vulcanization accelerator includes zinc glycerolate.

A method for producing a rubber composition for a tire according to the present invention comprises the steps of: (a) mixing carbon black and a vulcanization accelerator into raw rubber; And (b) adding and mixing at least one of a vulcanizing agent, a vulcanization accelerator, a dispersing agent, and an anti-aging agent in the mixed mixture; includes, wherein the vulcanization accelerator includes zinc glycerolate.

The rubber composition for a tire according to the present invention has an effect of improving modulus performance by adding zinc glycerolate as a vulcanization accelerator.

Specifically, the vulcanization accelerator of the present invention can improve the modulus and wear resistance (WEAR ABRASION) of the rubber composition in which the crosslinked structure is formed by increasing the crosslinking density of the rubber composition in which the raw rubber and carbon black are mixed.

Accordingly, the rubber composition for a tire of the present invention can manufacture a tire having excellent wear resistance.

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

The above-described objects, features and advantages will be described below in detail with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present invention pertains will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

Hereinafter, a rubber composition for a tire and a manufacturing method thereof according to some embodiments of the present invention will be described.

The manufacturing method of the rubber composition for a tire according to the present invention includes the step of mixing carbon black and a vulcanization accelerator into raw rubber (S110) and at least one of a vulcanizing agent, a vulcanization accelerator, a dispersing agent, and an anti-aging agent in the mixed mixture and mixing (S120).

In the step of mixing carbon black and a vulcanization accelerator into the raw rubber (S110), the carbon black may be coupled to the raw rubber through the interaction between the raw rubber and the carbon black.

For example, a hydrophilic functional group present on the surface of carbon black may have a hydrophilic interaction (eg, dipole interaction or hydrogen bonding) with a hydrophilic functional group on the surface of the raw rubber. The hydrophobic functional group present on the surface of the carbon black may be capable of hydrophobic interaction (eg, van-der wall force) or chemical bonding with a hydrophobic moiety of the raw rubber.

The raw rubber includes at least one of an isoprene-based rubber and a diene-based rubber. Preferably, it is preferable to use isoprene-based rubber, which has high repulsion elasticity, high strength, and high elasticity properties, and is advantageous in high abrasion resistance, fatigue fracture resistance, crack growth resistance, and the like.

The isoprene-based rubber may include natural rubber such as deproteinized natural rubber and high-purity natural rubber, or modified natural rubber such as epoxidized natural rubber, hydrogenated natural rubber, and grafted natural rubber.

The diene-based rubber may include styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene-containing styrene-butadiene rubber, or nitrile-containing styrene-butadiene rubber.

In addition to the above-mentioned raw rubber, neoprene rubber, chlorobutyl rubber or bromobutyl rubber may also be used.

As carbon black, furnace black, which collects carbon black produced by incomplete combustion of gas or oil, is mainly used. The reason furnace black is mainly used is that more than 98% of carbon black currently produced is made in the form of furnace black. Additionally, products manufactured by methods such as thermal black and channel black may also be used.

Carbon black is preferably added in an amount of 20 to 70 parts by weight based on 100 parts by weight of the raw rubber. When the content of carbon black is less than 20 parts by weight, there is a risk of being disadvantageous in mechanical properties including reinforcing properties. Conversely, when the content of carbon black exceeds 70 parts by weight, there is a concern that the Mooney viscosity, heat generation performance, and viscoelastic properties of the rubber composition are disadvantageous.

The vulcanization accelerator is used together with the vulcanization accelerator and is a compounding agent used to maximize the effect of accelerating the vulcanization. In the present invention, there is an effect of improving the modulus performance of the carbon black compound by changing the vulcanization accelerator.

The vulcanization accelerator according to the present invention preferably contains zinc glycerolate as an additive.

The zinc glycerolate may be represented by any one of the following [Formula 1], [Formula 2], and [Formula 3]. Zinc glycerolate is synonymous with Glyzinc, ZnGly, Zinc glyceroxide, Zinc glycerolate, and Zinc-m-glycerolate.

[Formula 1]

[Formula 2]

[Formula 3]

Zinc glycerolate, a special vulcanization accelerator of the present invention, is a vulcanization accelerator produced by reacting 1,2,3-propanetriol with Zn ions. Zinc glycerolate is a raw material mainly used as a crosslinking additive in cosmetics and plastic products.

The vulcanization accelerator is preferably added in an amount of 1 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the raw rubber.

When the content of the vulcanization accelerator is less than 1 part by weight, it may be difficult to achieve sufficient modulus and abrasion resistance because the effect of promoting crosslinking of the rubber composition in which the raw rubber and carbon black are mixed by the vulcanization additive is insignificant. Conversely, when the content of the vulcanization accelerator exceeds 5 parts by weight, there is a risk that the rubber processability may be lowered or the abrasion resistance of the rubber composition made of rubber and carbon black may be lowered due to the fast optimal crosslinking rate due to the use of an excessive amount of the crosslinking accelerator. .

The vulcanization accelerator may be used alone, but zinc glycerolate and zinc oxide may be mixed as needed. For example, a vulcanization accelerator in which 2 parts by weight of zinc glycerolate and 1 part by weight of zinc oxide are mixed may be added.

The first mixing in step (S110) may be performed at 100 to 170° C. for 30 seconds to 60 minutes, and the temperature and time are adjusted within this range so that the raw rubber, carbon black, and the vulcanization accelerator are smoothly stirred. can do.

In addition, in the step (S110), a reinforcing agent such as silica, clay or talc may be additionally added within a range that does not affect the processability of the rubber composition.

Next, at least one of a vulcanizing agent, a vulcanization accelerator, a dispersing agent, and an anti-aging agent is added to the mixed mixture and secondarily blended.

The rubber composition according to the present invention may further include one or more of a vulcanizing agent, a vulcanization accelerator, a dispersing agent, and an anti-aging agent within a range that does not affect the processability of the rubber composition in which the raw rubber and carbon black are mixed.

The vulcanizing agent is a sulfur-based vulcanizing agent, an inorganic vulcanizing agent such as powdered sulfur (S), insoluble sulfur (S), and precipitated sulfur (S), tetramethylthiuram disulfide (TMTD), tetraethyltriuram disulfide, TETD), and an organic vulcanizing agent such as dithiodimorpholine.

The vulcanization accelerator refers to an accelerator that accelerates the vulcanization rate or delays action in the initial vulcanization stage. The vulcanization accelerator may include sulfinamide, thiazole-based, thiuram-based, and the like. Sulfinamide is N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazylsulfenamide (TBBS), N,N-dicyclohexyl-2-benzothiazylsulfenide amide, N-oxydiethylene-2-benzothiazylsulfenamide, and N,N-diisopropyl-2-benzothiazolesulfenamide. Thiazoles are 2-mercaptobenzothiazole (MBT), dibenzothiazyldisulfide (MBTS), sodium salt of 2-mercaptobenzothiazole, zinc salt of 2-mercaptobenzothiazole, 2-mercaptobenzo Copper salt of thiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl4-morpholino thio)benzothiazole. Thiuram-based compounds may include at least one of tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram disulfide, and dipentamethylenethiuram monosulfide.

The dispersant may include a wax such as stearic acid and the like.

Anti-aging agents are additives used to stop the chain reaction in which tires are automatically oxidized by oxygen. The antioxidant may include at least one of amine-based, phenol-based, quinoline-based, imidazole-based, and carbamic acid metal salts.

The secondary compounding of the step (S120) may be performed at 60 to 150° C. for 30 seconds to 60 minutes, and by controlling the temperature and time within this range, the additive can be smoothly stirred in the firstly formulated mixture. have.

As such, the rubber composition for a tire manufactured according to the present invention includes raw rubber, carbon black, and a vulcanization accelerator, and the vulcanization accelerator is represented by any one of [Formula 1], [Formula 2], and [Formula 3] and zinc glycerolate.

A tire manufactured using the above-described rubber composition for a tire is provided. For example, the rubber composition may be prepared as a rubber member for a tire such as a carcass, belt, bead or tread using a kneader such as a Banbury mixer or an open roll.

As described above, specific examples of the rubber composition for a tire and a manufacturing method thereof will be described as follows.

1. Preparation of rubber composition for tire

Example One

100 parts by weight of natural rubber, 50 parts by weight of carbon black, 1 part by weight of anti-aging agent (6PPD) and 5 parts by weight of a vulcanization accelerator (Zinc-m-glycerolate) represented by Formula 1 were blended at 160° C. for 3 minutes, and 165° C. was released from Then, 4.5 parts by weight of sulfur and 1.2 parts by weight of a vulcanization accelerator (TBBS) were added at 105° C. as a secondary compounding method and mixed for 2 minutes to prepare a rubber composition.

Example 2

A rubber composition was prepared in the same manner as in Example 1, except that 1 part by weight of STEARIC ACID was further added as a vulcanization accelerator.

Example 3

A rubber composition was prepared in the same manner as in Example 1, except that 1 part by weight of the vulcanization accelerator (Zinc-m-glycerolate) was used.

Example 4

A rubber composition was prepared in the same manner as in Example 1, except that 100 parts by weight of natural rubber mixed with natural rubber: synthetic rubber in a weight ratio of 8:2 was used.

Example 5

A rubber composition was prepared in the same manner as in Example 1, except that 2 parts by weight of zinc-m-glycerolate and 1 part by weight of zinc oxide (ZnO) were mixed and used as a vulcanization accelerator.

comparative example One

100 parts by weight of natural rubber, 50 parts by weight of carbon black, 3 parts by weight of vulcanization accelerator (ZnO), 1 part by weight of vulcanization accelerator (stearic acid), and 1 part by weight of antioxidant (6PPD) at 160° C. for 3 minutes, Released at 165°C. Then, 4.5 parts by weight of sulfur and 1.2 parts by weight of a vulcanization accelerator (TBBS) were added at 105° C. as a secondary compounding method and mixed for 2 minutes to prepare a rubber composition.

2. Methods for evaluating physical properties and their results

The physical properties of the rubber compositions prepared according to Examples and Comparative Examples were evaluated in the following manner.

Experimental example 1. Evaluation of physical properties of rubber compositions

1) Pattern viscosity (ML1+4, 100℃): The pattern viscosity was measured for each rubber composition prepared in each Example and Comparative Example according to ASTM D 1646 RUBBER FROM NATURAL OR SYNTHETIC SOURCES-VISCOSITY AND VULCANIZATION CHARACTERISTICS (MOONEY VISCOMTER). did.

50-ML1+4 (100℃) Here, 50-M is the number of viscosity, L is the use of LARGE ROTOR, 1 means preheating for 1 minute before operating the motor, 4 is the specified measurement time 100 ℃ means the measurement temperature.

The higher the pattern viscosity, the lower the dispersibility of the components in the rubber composition.

2) Pattern scorch time (MST): The pattern scorch time (MST) for the rubber compositions prepared in each Example and Comparative Example according to ASTM D 1646: Rubber - Viscosity, Stress Relaxation, and Pre-Vulcanization characteristics (Mooney Viscometer) Each was measured.

If the MST is short, scorch may occur quickly, which may reduce the processability of rubber during the tire manufacturing process.

3) Rheometer (MDR): Rheometer (MDR) was measured for each of the rubber compositions prepared in Examples and Comparative Examples according to ASTM D1349, ASTM D1556, ASTM D2084, ASTM D4483, ISO 6502, ASTM D 5289.

As the t90 time of the rheometer increases, there is a problem in that the productivity of the tire manufacturing process, particularly in the vulcanization process, decreases.

division pattern viscosity
(Rubber composition) MST, t5 (138℃) T90 (150℃) Tmax (150℃) Example 1 70 4.9 5.5 33.9 Example 2 71 5.0 5.8 33.5 Example 3 70 4.8 5.2 39.0 Example 4 68 4.9 5.6 34.1 Example 5 70 4.8 5.4 34.5 Comparative Example 1 70 5.2 7.0 27.4

Referring to the results in Table 1, in the case of Examples 1 to 5, the pattern viscosity values measured in the rubber composition compared to Comparative Example 1 can be confirmed at the same level. In general, when the dispersibility increases, the MV viscosity value tends to decrease.

From the results of Table 1, it can be seen that the dispersion of rubber and carbon black was made at the same level in Examples 1 to 5 and Comparative Example 1. However, as a result of the RHEOMETER evaluation, it can be confirmed that the T90 value indicating the optimal vulcanization time from Examples 1 to 5 has a faster value than Comparative Example 1.

In addition, Tmax is a value having a similar tendency to the change tendency of the modulus, and compared to Comparative Example 1, all of the Tmax values tend to be upward, and the modulus is expected to increase compared to Comparative Example 1 in the modulus properties. This is related to the formation of crosslinking density, and it is determined that Examples 1 to 5 have a higher crosslinking density than Comparative Example 1.

Experimental example 2. Evaluation of the physical properties of rubber sheets

According to ASTM D 3182 RUBBER- PREPARING STANDARD VULCANIZED SHEET, rubber sheets were prepared using the rubber compositions prepared according to Examples and Comparative Examples. The physical properties of the rubber sheets prepared by using the rubber compositions prepared according to Examples and Comparative Examples were evaluated in the following manner.

1) Hardness: Rubber hardness was measured according to the ASTM D2240 SHORE A2-TYPE rubber hardness tester. The hardness of the rubber sheet is regarded as a property of the degree to which it enters the surface of the rubber sheet under a prescribed pressure with a standard-sized indentor.

2) Tensile stress (M300%) and elongation (ELONGATION) were measured according to ASTM 412-98a: STANDARD TEST METHODS FOR VULCANIZED RUBBER AND THERMOPLASTIC ELASTOMERS-TENSION.

3) Heat buildup (HBU): HBU was measured according to ASTM D623 and ASTM D3182. The larger the HBU value, the smaller the heat generation is.

4) Rebound: Measured according to ASTM D 2632: RUBBER PROPERTY - RESILIENCE VERTICAL REBOUND, ASTM D 1054: RUBBER PROPERTY - RESILIENCE USING A REBOUND PENDULUM. The larger the rebound value, the larger the elastic term, so the heat loss is small.

5) DMA: Measured according to ASTM D4065, D4440, D5279. tanδ60℃ As a substitute value for rolling resistance, the smaller the value, the better the performance.

6) Lambourn abrasion loss: measured according to JIS K6264-93, JIS R6211, JIS R6210, JIS R6111. The smaller the Lambourn value, the smaller the loss.

test Hardness M300% Elong. HBU Rebound. tanδ60℃ Lamborn Example 1 73 174 530 25 48 0.09646 0.0574 Example 2 72 172 535 25 48 0.09642 0.0575 Example 3 72 192 505 23 51 0.09519 0.0590 Example 4 73 176 540 25 47 0.09651 0.0572 Example 5 73 179 521 25 48 0.09655 0.0577 Comparative Example 1 71 159 569 27 48 0.09811 0.0602

Referring to Table 2, it can be seen that Examples 1 to 5 have higher modulus properties compared to Comparative Example 1. At the same time, when the modulus is high, the ELONGATION tends to be lowered, but the ELONGATION values are all above 500%, which is a satisfactory level. These characteristics can be confirmed through viscoelasticity and HBU characteristics.

It can be seen that the tanδ60°C value has a low value in the rubber compositions of Examples 1 to 5, which have higher crosslinking density compared to Comparative Example 1. It is judged that the decrease in heat energy loss due to the reduction of HYSTERESIS that can come out between rubber and carbon black or carbon black and carbon black is considered to have had an effect. However, it can be seen that wear tends to decrease slightly above the appropriate level of modulus.

As described above, the present invention has been described with reference to the illustrated drawings, but the present invention is not limited by the embodiments and drawings disclosed in the present specification. It is obvious that variations can be made. In addition, although the effects according to the configuration of the present invention are not explicitly described and described while describing the embodiments of the present invention, it is natural that the effects predictable by the configuration should also be recognized.

Claims (6)

Including raw rubber, carbon black, and a vulcanization accelerator;
The vulcanization accelerator includes zinc glycerolate,
A rubber composition for a tire comprising 20 to 70 parts by weight of carbon black based on 100 parts by weight of the raw rubber.
The method of claim 1,
The raw rubber is a rubber composition for a tire comprising at least one of an isoprene-based rubber and a diene-based rubber.
The method of claim 1,
wherein the vulcanization accelerator further comprises zinc oxide.
The method of claim 1,
The rubber composition for tires further comprises at least one of a vulcanizing agent, a vulcanization accelerator, a dispersing agent, and an anti-aging agent.
The method of claim 1,
A rubber composition for a tire comprising 1 to 10 parts by weight of a vulcanization accelerator based on 100 parts by weight of the raw rubber.
(a) mixing by adding carbon black and a vulcanization accelerator to the raw rubber; and
(b) adding and mixing at least one of a vulcanizing agent, a vulcanization accelerator, a dispersing agent, and an anti-aging agent to the mixed mixture;
The vulcanization accelerator includes zinc glycerolate,
A method of manufacturing a rubber composition for a tire comprising 20 to 70 parts by weight of carbon black with respect to 100 parts by weight of the raw rubber.