KR20230053769A - Rubber composition mixing method for compound of tire quality uniformity - Google Patents

Abstract

The present invention relates to a method for mixing a tire rubber composition to ensure the uniformity of tire compound, and more specifically, to a method for mixing a tire rubber composition, capable of minimizing the variation of mixed rubber by varying a mixing method of a master batch, wherein the method comprises: a first step of mixing master batch rubber compositions to prepare at least two master batches; a second step of re-milling the at least two master batches to be mixed with each other to prepare a re-milled master batch; and a third step of mixing a vulcanizing agent into the re-milling master batch.

Description

Method of mixing tire rubber composition to ensure uniformity of tire compound quality {RUBBER COMPOSITION MIXING METHOD FOR COMPOUND OF TIRE QUALITY UNIFORMITY}

The present invention relates to a method of compounding a tire compound, and relates to a method of compounding a tire rubber composition for securing uniformity in quality of a tire compound.

Tires play a role of supporting the load of a vehicle, mitigating shock generated from a road surface, and at the same time transmitting power and braking force of an automobile engine to the road surface to maintain motion of the vehicle. The required characteristics of such vehicle tires include durability, abrasion resistance, rolling resistance, fuel economy, steering stability, riding comfort, braking performance, vibration, noise, and the like.

Recently, as vehicles become more sophisticated and safety requirements increase, the development of high-performance tires capable of maintaining optimum performance in various road surfaces and climates is required.

A tire rubber composition is generally composed of raw rubber, filler, and other additives, and the physical properties required as a tire, such as rolling resistance, durability, and grip, are adjusted by changing the compound composition or mixing method thereof.

However, it is difficult to secure uniformity of quality due to large deviations in the quality of the compounded tire compounds in the existing compounding method.

Republic of Korea Patent Registration No. 10-0886119

In view of the above, an object of the present invention is to prepare at least two or more master batches by mixing a master batch rubber composition including a silica compound, and remilling and dispersing them to form a final uniform crosslinked structure to form a compounded rubber. It is intended to provide a new tire rubber composition compounding method capable of improving tire properties by minimizing variation.

In order to achieve the above object, the tire rubber composition of the present invention is formulated by mixing at least two master batch rubber compositions including raw material rubber, silica as a filler, a silane coupling agent, stearic acid, and an anti-aging agent. A first step of producing the above master batch, a second step of preparing a remilling master batch by re-milling such that at least two or more master batches are mixed with each other, and a vulcanizing agent to the remilling master batch The third step of blending is included.

In the master batch rubber composition, the raw material rubber is natural rubber (NR), butadiene rubber (BR), styrene butadiene rubber (SBR), solution polymerized styrene-butadiene rubber (SSBR), isoprene rubber (IR), chloroprene rubber (CR) , acrylonitrile butadiene rubber (NBR), isobutyrene isoprene rubber (IIR), ethylene propylene copolymer synthetic rubber (EPM), ethylene and propylene non-conjugated diene terpolymer synthetic rubber (EPDM), chlorosulfonated polyethylene rubber ( CSM), acrylic rubber (ACM), chloride rubber (CO), epichlorohydrin rubber (ECO), polysulfide rubber, silicone rubber, fluoro rubber (FKM) and urethane rubber (U) can do.

The master batch rubber composition includes 40 to 80 parts by weight of the silica, 3 to 9 parts by weight of the silane coupling agent, 0.1 to 2 parts by weight of the stearic acid, and 1 part by weight of the antiaging agent, based on 100 parts by weight of the raw rubber. to 5 parts by weight.

The vulcanizing agent may include diphenyl guanidine, N-cyclohexyl-2-benzothiazole sulfonamide, and zinc oxide (ZnO) as sulfur and a vulcanization accelerator. .

The vulcanizing agent may include 1 to 5 parts by weight of the sulfur and 1 to 5 parts by weight of the vulcanization accelerator, based on 100 parts by weight of the raw rubber.

By uniformly blending the tire compound through the tire rubber composition compounding method of the present invention, the performance of the tire can be improved by minimizing the variation in physical properties of the compounded rubber.

1 is a flow chart of a method for compounding the tire rubber composition of the present invention.
Figure 2 briefly shows the method of compounding the tire rubber composition for each step in Comparative Examples and Examples of the present invention.

The tire rubber composition of the present invention includes raw rubber, filler, vulcanization agent, vulcanization accelerator, and other processing aids, and various performances are expressed depending on the composition and the mixing method of these compositions.

1 is a flow chart of a method for compounding the tire rubber composition of the present invention.

As shown in FIG. 1, the method of compounding the tire rubber composition of the present invention includes a first step of preparing a master batch by mixing the rubber composition (S110), and a second step of re-milling the master batch (S110). S120), and a third step (S130) of blending a vulcanizing agent.

In the first step (S110), a master batch is prepared by mixing a master batch rubber composition including a raw material rubber, silica as a filler, a silane coupling agent, stearic acid, and an anti-aging agent.

In the first step (S110), it is preferable to manufacture at least two master batches, and each master batch has the same composition.

In this specification, the term "master batch" means mixing and kneading a compounding agent at a higher concentration than the prescription in advance in the process of mixing the compounding agent with the raw rubber, and mixing it into the raw rubber to accurately measure each compounding agent. can, improve dispersion, and prevent scattering during work.

In the first step (S110), the master batch rubber composition is preferably mixed at a temperature of 120 to 160 °C. If the mixing temperature exceeds 160 ° C in the first step, a scorch problem occurs due to high temperature, and conversely, if the mixing temperature is less than 120 ° C, the mixing of the rubber composition is not properly performed and the master batch is not formed properly.

In the first step (S110), the raw material rubber in the master batch rubber composition is not particularly limited, and natural rubber (NR), synthetic rubber, and a mixture thereof may be used as rubber commonly used in the tire industry.

Examples of the synthetic rubber include butadiene rubber (BR), styrene butadiene rubber (SBR), solution polymerized styrene-butadiene rubber (SSBR), isoprene rubber (IR), chloroprene rubber (CR), acrylonitrile butadiene rubber ( NBR), isobutylene isoprene rubber (IIR), ethylene propylene copolymer synthetic rubber (EPM), ethylene and propylene non-conjugated diene terpolymer synthetic rubber (EPDM), chlorosulfonated polyethylene rubber (CSM), acrylic rubber (ACM) ), chloridrin rubber (CO), epichlorohydrin rubber (ECO), polysulfide rubber, silicone rubber, fluororubber (FKM), and urethane rubber (U).

Preferably, a mixture of natural rubber, styrene-butadiene rubber (SBR), and solution-polymerized styrene-butadiene rubber (SSBR) may be used as the raw material rubber.

In the master batch rubber composition, the silica is a filler added to improve physical properties such as mechanical strength, shock absorption, and durability of a tire, and carbon black may be used as a filler instead of the silica.

The silica may be included in an amount of 40 to 80 parts by weight based on 100 parts by weight of the raw rubber composition. If the silica content decreases the mechanical strength and physical properties of the tire, it is preferable to satisfy the above range.

When using silica as a filler in the master batch rubber composition, a silane coupling agent may be included in order to further enhance the reinforcing effect by further improving durability of the rubber composition of silica.

The silane coupling agent is, for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4- Epoxycyclohexyl)ethyltrimethoxysilane and other epoxy group-containing silane coupling agents, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxy Amino group-containing silane coupling agents such as silyl-N-(1,3-dimethylbutylidene)propylamine and N-phenyl-γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3- (meth)acrylic group-containing silane coupling agents such as methacryloxypropyltriethoxysilane, isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane, bis-3-(triethoxylyl)propyl tetrasulfide ( bis 3-(triethoxysilyl)propyl tetrasulfide, Si-69) and the like can be used. The said silane coupling agent may be used independently, or it can mix and use 2 or more types.

Although the amount of the silane coupling agent varies depending on the type of the silane coupling agent, the amount of silica, etc., it is preferable to include 1 to 20 parts by weight of the silane coupling agent based on 100 parts by weight of the raw rubber.

In the master batch rubber composition, stearic acid is a vulcanization accelerator that serves to accelerate the vulcanization reaction, and the stearic acid is preferably included in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the raw rubber.

The tire rubber composition may further include various additives such as rubber anti-aging agents and anti-oxidants as general additives for rubber compositions in addition to the components listed above. It is preferably included in parts by weight, but the content thereof may be used in conventional tire rubber compositions, and is not particularly limited.

In the method of compounding the tire rubber composition, in the second step (S120), the master batch prepared in the first step (S130) is re-milled to be mixed with each other to prepare a re-milling master batch.

In the second step (S120), re-milling, which is called a re-lowering process, re-mills the at least two or more master batches so that they are mixed with each other, and is uniformly mixed by a common mixing method such as a mill. do.

In the third step (S130), a curing agent is added to and mixed with the remilling master batch prepared in the second step (S120), and sulfur is added to the curing agent.

In the third step (S130), a vulcanization accelerator is added together to shorten the vulcanization time by accelerating the vulcanization power with sulfur, lower the vulcanization temperature, and reduce the amount of sulfur used.

The vulcanization accelerator accelerates the vulcanizing power of the vulcanizing agent to shorten the vulcanizing time, lower the vulcanizing temperature, and reduce the amount of the vulcanizing agent, and is added together with the sulfur. The vulcanization accelerator is not particularly limited, but preferably includes 2-Mercapto benzo thiazole, tetramethylthiuram disulfide, and zinc dibutyl dithiocarbamate. ), diphenyl guanidine, N-cyclohexyl-2-benzothiazole sulfonamide, and zinc oxide (ZnO).

The amount of the vulcanization accelerator is preferably used in the range of 1 to 5 parts by weight based on 100 parts by weight of raw rubber. If the vulcanization reaction does not sufficiently occur within the above-mentioned content range, unvulcanization or early vulcanization causes vulcanization during processing, reducing plasticity and increasing elasticity, thereby making it impossible to process the product. It is desirable to be satisfied.

In the third step (S130), a vulcanizing agent is added and mixed at a temperature of 80 ° C to 125 ° C. If the temperature exceeds 125 ° C., the vulcanization reaction proceeds during the mixing process due to the reaction between the added sulfur and the vulcanization accelerator, resulting in scorching.

The present invention will be described in more detail through the following examples.

Table 1 below shows the composition of a tire rubber composition according to an embodiment, and the content unit of the components described in Table 1 is parts by weight of the compounding agent with respect to 100 parts by weight of raw rubber.

step compounding agent Mixing ratio (parts by weight) Step 1
(MB-A) NR 25 SSBR SOL 5251H (KKPC) 50 BR 25 silica 80 Si-69 6.4 stearic acid One anti aging 2 step 2
(Re-mill) MB-A step 3
(FB) brimstone 1.5 CBS 1.3 DPG 1.5 ZnO 2

N-(1,3-DIMETHYLBUTYL)-N-PHENYL-PPHENYLENDIAMINE was used as the anti-aging agent in Table 1, and CBS, DPG, and ZnO, except for sulfur in the third step, were vulcanization accelerators, and DPG was diphenyl Guanidine (Diphenyl Guanidine), CBS is N-cyclohexyl-2-benzothiazole sulfonamide (N-cyclohexyl-2-benzothiazole sulfonamide), and ZnO represents zinc oxide.

Figure 2 briefly shows the method of compounding the tire rubber composition of Table 1 in each step in Comparative Examples and Examples of the present invention.

As shown in FIG. 2, in Comparative Example 1, the tire rubber composition is compounded except for the process of re-milling the master batch prepared by the conventional compounding method.

Terms such as #1, #2, #3, and #4 shown in FIG. 2 are used only for distinguishing purposes in describing a plurality of master batches.

Comparative Example 2 is a blending method that includes a second step of re-milling, but does not mix the master batch prepared in the first step.

Example 1 is a method of mixing and blending two master batches prepared in the first step in re-milling in the second step, as shown in FIG. The case consists of a first master batch (#5) and another second master batch (#6), half of the total content of the first master batch (#5) and the total content of the second master batch (#6) A tire rubber composition may be formulated by mixing half of each.

Table 2 evaluates the following physical properties of the tire rubber compositions prepared through Comparative Example 1, Comparative Example 2, and Example 1, and the results are shown in Table 2 below.

Mooney viscosity (MV) was measured for Mooney viscosity (ML 1+4 (100° C.)) of the rubber composition according to ASTM standard D1646.

Scorch is Mooney scorch, and the time (t5) required for the measured scorch viscosity to rise by 5 points from the minimum value was measured.

A rheometer (Rheomwter, Rheo) is a tester that evaluates the processability and vulcanization characteristics of unvulcanized rubber. Using MDR-2000 (ALPHA Technologies), constant sinusoidal vibration is applied without destroying the rubber specimen under constant temperature and pressure to measure the specimen from the specimen. The applied force was converted into torque to evaluate the rubber properties from the unvulcanized state to the overvulcanized state.

In general physical properties, hardness (HD) was measured using a Shore A type hardness tester, and hardness indicates the degree of hardness of a rubber specimen.

300% modulus (M-300%) is the tensile strength (kg/cm ² ) of a rubber specimen at 300% elongation in a tensile test and was measured according to ASTM standard D412. The higher the 300% modulus, the higher the strength. .

Tensile properties were measured using a tensile tester (INSTRON) according to ASTM D412 to measure the tensile strength of crosslinked rubber specimens. The specimen for measurement was manufactured in a sheet form using a hydraulic press and produced in a dumbbell form using a specimen cutter. Tensile strength test conditions were measured at a tensile speed of 500 mm/min at room temperature. Tensile strength (T/S) is a value representing the stress value until the test piece breaks in the tensile tester, and the force received per unit area is measured.

Elongation was measured by a method of expressing the strain value in % until the rubber specimen for measurement was broken in a tensile tester (INSTRON).

Viscoelastomer characteristics were measured for tan δ values from -80 ° C to 70 ° C under a 10 Hz Frequency at 0.2% strain using a Gabo viscometer. At this time, the temperature with the largest tan δ value was defined as the glass transition temperature (Tg), and the tan δ value in the 0 °C region and the tan δ value in the 60 °C region were measured.

For the wet friction characteristics, the maximum frictional force was measured through the change in speed of the sample after free rolling the sample to which a vertical load was applied on a wet road rotating at a speed of 30 km/h. The braking force coefficient was measured as the average of three values excluding the maximum/minimum values among the maximum friction force (μ-Peak) values derived from the driving evaluation.

division Comparative Example 1 Comparative Example 2 Example 1 Mean (n=3) Deviation (n=3) Mean (n=3) Deviation (n=3) Mean (n=3) Deviation (n=3) Unvulcanized properties MV (viscosity) - 73 2.9 70 2.5 70 1.2 Scorch (t5) minute 18.2 1.3 21.2 0.5 17.7 0.4 Rheo T40 minute 4.5 0.1 4.8 0.1 4.6 0.1 common
Properties Hardness
(Shore A) - 68 One 67 One 68 0 300%
modulus kgf/cm ² 102 6 93 7 90 7 tensile strength kgf/cm ² 192 6 194 6 183 6 elongation rate % 500 25 530 20 550 12 Wet
frictional properties μPEAK Avg. - 0.513 0.11 0.526 0.003 0.527 0.003 viscoelasticity Tg ℃ -29 1.8 -30 1.9 -28 1.8 tanδ (0℃) - 0.269 0.015 0.284 0.013 0.276 0.006 tanδ (60℃) - 0.121 0.004 0.122 0.004 0.124 0.001

According to the results of Table 2, most of the physical properties of Comparative Example and Example were similar, but when examining the elongation, the elongation of Example 1 was superior to that of Comparative Example 1 and Comparative Example 2, and the deviation was also small. can know

When looking at viscoelasticity as another physical property, the tan δ (transgent delta) value means the ratio of the elastic modulus lost to the stored elastic modulus. The energy loss characteristics of the tire specimen were used for measurement, and the energy loss value The lower the value, the smaller the energy loss, indicating the excellent fuel efficiency. Considering this point, it can be seen that the value of tan δ of Example 1 is low, the fuel consumption performance is excellent, and the deviation of these values is less than that of Comparative Example 1 and Comparative Example 2.

As described above, when at least two or more master batches prepared in the first step are combined and re-milled, the tire rubber composition is uniformly blended, and the physical properties of the compounded rubber produced in Comparative Example 1 and Comparative Example 2 are similar. It can be confirmed that it is almost equally excellent compared to the rubber composition of the tire, and has an effect of improving the performance of the tire by minimizing the variation between tire rubber compositions.

These results show that the quality uniformity of the tire compound is higher when three master batches are combined and mixed than when two master batches are combined and mixed during re-milling in the second step. can know that Therefore, according to the present invention, tire performance can be improved by simply uniformly mixing a tire compound through a method of mixing a tire rubber composition in which at least two or more master batches are remilled to be mixed with each other.

Claims (6)

A first step of preparing at least two master batches by mixing a master batch rubber composition including a raw material rubber, silica as a filler, a silane coupling agent, stearic acid, and an anti-aging agent;
A second step of preparing a re-milling master batch by re-milling the at least two or more master batches so that they are mixed with each other; and
A method for blending a tire rubber composition comprising a; third step of blending a vulcanizing agent into the remilling master batch. According to claim 1,
The raw material rubber is natural rubber, butadiene rubber, styrene butadiene rubber, solution polymerization styrene-butadiene rubber, isoprene rubber, chloroprene rubber, acrylonitrile butadiene rubber, isobutyrene isoprene rubber, ethylene propylene copolymer synthetic rubber, ethylene and propylene nostril Characterized in that it comprises at least one selected from acrylonitrile terpolymer synthetic rubber, chlorosulfonated polyethylene rubber, acrylic rubber, chloridrin rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluororubber and urethane rubber A method of compounding a tire rubber composition to be. According to claim 1,
The master batch rubber composition is based on 100 parts by weight of the raw rubber,
40 to 80 parts by weight of the silica;
1 to 20 parts by weight of the silane coupling agent;
0.1 to 2 parts by weight of the stearic acid; and
1 to 5 parts by weight of the anti-aging agent. According to claim 1,
The method of compounding a tire rubber composition, characterized in that the vulcanization agent comprises sulfur and a vulcanization accelerator. According to claim 4,
The tire rubber composition, characterized in that the vulcanization accelerator comprises diphenyl guanidine, N-cyclohexyl-2-benzothiazole sulfonamide and zinc oxide (ZnO) compounding method. According to claim 4,
The vulcanizing agent is based on 100 parts by weight of the raw rubber,
The sulfur is included in 1 to 5 parts by weight,
A method of compounding a tire rubber composition, characterized in that the vulcanization accelerator is included in 1 to 5 parts by weight.

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