KR20200025748A - Rubber composition for under tread with high hardness and the preparing method thereof - Google Patents

Abstract

The present invention relates to a rubber composition for an under tread of an automobile tire. More specifically, the present invention relates to a rubber composition for a high hardness under tread and a manufacturing method thereof. To this end, the rubber composition for an under tread comprises structurally developed carbon black based on 100 parts by weight of raw rubber composed of first butadiene rubber having a cis-1,4 bond content of 90 wt% of higher and second butadiene rubber comprising 10-50 parts by weight of syndiotactic 1,2-polybatadiene particles having a regular syndiotactic structure based on 100 parts by weight of diene-based rubber. According to the present invention, the rubber composition is suitable for high-performance vehicles by increasing rigidity of rubber with no loss of fuel efficiency.

Description

Rubber composition for high-hardness undertread and manufacturing method therefor {RUBBER COMPOSITION FOR UNDER TREAD WITH HIGH HARDNESS AND THE PREPARING METHOD THEREOF}

The present invention relates to a rubber composition for under tread of an automobile tire, and more particularly, to an undertrade including functional butadiene rubber containing particles having a regular syndiotactic structure and highly rigid carbon black having advanced structure. The present invention relates to a rubber composition for hardened undertread and a method of manufacturing the same, which is suitable for a high-performance vehicle by increasing the rigidity of the rubber through the rubber composition and at the same time, there is no loss of fuel efficiency.

Among the various performances of the vehicle, the demand for driving performance along with fuel economy is gradually increasing. As the number of consumers wanting a driving sense is increasing and the foot of high-performance vehicles is actively progressing in recent years, the importance of driving and ride comfort (Ride & Handling, R & H) performance is increasing.

Tires are one of the important automotive components that can affect both driving comfort and ride comfort (Ride & Handling, R & H), noise, vibration, friction (Nosie, Vibration, Harshness, NVH) and fuel efficiency. At the same time, a lot of research is being conducted to improve the driving comfort and ride performance of tires. To this end, the stiffness of the tire structure and the rubber material is basically increased. If the stiffness of the material is increased, the response to steering during steering is increased, and the driving and riding performance of the tire is improved.

However, in general, when only the stiffness of the tire is increased, the filler content is increased in the rubber composition of the tire, thereby causing a problem in that the tire fuel efficiency is lowered. In recent years, the demand for fuel efficiency is also increased in high-performance vehicle tires. Therefore, there is a demand for a technology that can solve the problem of deterioration in fuel efficiency beyond simply increasing tire stiffness.

Republic of Korea Patent No. 10-0962622 (2010.06.03)

Accordingly, the present invention in consideration of the above point is to improve the hardness of the under-tread of the tire and at the same time to improve the fuel efficiency of the material by applying the carbon black with advanced structure to reduce the hardness of the conventional carbon black used previously It is possible to reduce the carbon black agglomeration generated inside the rubber composition by improving the performance and material fuel efficiency, as well as reducing the amount of general carbon black, and for the hard undertread, which is an eco-friendly manufacturing process due to less filler dust generation. It is an object to provide a rubber composition and a method for producing the same.

Rubber composition for undertrade of the present invention for achieving the above object is a raw rubber 100 containing 20 to 80% by weight of natural rubber, 10 to 40% by weight of the first butadiene rubber and 10 to 40% by weight of the second butadiene rubber Based on the weight part, it comprises 20 to 60 parts by weight of carbon black.

The natural rubber may generally be used natural rubber or purified natural rubber used in the rubber industry.

If the natural rubber content of the raw material rubber is less than 20% by weight, physical properties such as mechanical performance, processability and adhesiveness may be lowered.On the contrary, when the natural rubber content exceeds 80% by weight, low temperature performance, fatigue resistance and rubber elasticity Since it may be lowered, it is preferable to satisfy the content range of 20 to 80% by weight of the raw material rubber.

The first butadiene rubber is a polybutadiene rubber having a cis-1,4 (cis-1,4) bonding content of 90% by weight or more, and the second butadiene rubber is a functional rubber and is regular based on 100 parts by weight of a total of diene rubber. Syndiotactic 1,2-polybatadiene particles having an alternating structure (syndiotactic structure) is to comprise 10 to 50 parts by weight.

When the content of the second butadiene rubber is less than 10% by weight of the raw material rubber, the reinforcing effect of the hardness property is lowered. On the contrary, when the content of the second butadiene rubber is more than 40% by weight, the filling property is excessively applied to the material fuel efficiency and other mechanical properties. Since this problem is lowered, the content of the second butadiene rubber is preferably 10 to 40% by weight of the raw material rubber.

1 and 2, the carbon black, which is a filler used in the present invention, is a high rigid carbon black (also referred to as a 'structural development carbon black') having a structure of dibutyl phthalate. It is preferable that (dubutyl phthalate, DBT) oil absorption amount is 170-200 ml / 100g, and nitrogen specific surface area adsorption amount is 30-50 m <^2> / g.

Figure 2 is a schematic diagram of high carbon black particles used in the general carbon black and the undertread composition of the present invention, as shown in Figure 2 N330, N339, N347, N351, N375, N550, N650, N660, N765, N772 General carbon black, which is a general-purpose carbon black such as N683 and the like, exists by simply agglomerating spherical particles in a circular general form. However, in contrast, the structure development black carbon used in the present invention has spherical particles in the form of a branched structure, which exhibits good physical properties due to a higher bonding force with rubber than a simple agglomerated general black carbon.

When the content of the carbon black is less than 20 parts by weight based on 100 parts by weight of the raw material rubber, the filling property is lowered, and the mechanical properties of the tire under tread are lowered. Due to the excessive increase in physical properties, the dispersibility of the carbon black is lowered, the friction between the filler is increased and the heat generation property is worsened, so that the fuel efficiency of the material is degraded, the content of the carbon black is 100 parts by weight of the raw rubber It is preferably included in 20 to 60 parts by weight.

The rubber composition for undertrade according to the present invention, in addition to the above components, various additives commonly used in the rubber industry, specifically vulcanizing agents, vulcanization accelerators, zinc white, stearic acid antioxidants, antioxidants and process oils And the like. It is preferable that the compounding quantity of these additives is 10-30 weight part with respect to 100 weight part of said raw material rubbers.

The vulcanizing agent is not particularly limited and may be appropriately selected and used depending on the composition of the polymer, the molecular distribution state, the structure, and the like. "Varulose" shows the bridge | crosslinking through at least 1 sulfur atom here.

As a vulcanization accelerator, Thiuram type accelerators, such as tetramethyl thiuram monosulfide, tetramethyl thiuram disulfide, and tetraethyl thiuram disulfide; Thiazole-based accelerators such as 2-mercaptobenzothiazole and dibenzothiazyl disulfide; Sulfenamide-based accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide and N-oxydiethylene-2-benzothiazolylsulfenamide; Guanidine-based accelerators such as diphenylguanidine and diorthotriguanidine; aldehyde-amine accelerators such as n-butylaldehyde-aniline condensate and butylaldehyde-monobutylamine condensate; Aldehyde-ammonia-based accelerators such as hexamethylenetetramine; One or more thiourea-based accelerators such as thiocarbanilide and the like can be used.

Specific examples of the anti-aging agent include N-isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, 6-ethoxy- 2,2,4-trimethyl-1,2-dihydroquinoline or the high temperature condensate of diphenylamine and acetone, etc. are mentioned.

The process oil acts as a softener in the rubber composition, specifically, may be a paraffinic, naphthenic, or aromatic compound, and more specifically, aromatic process oil, hysteresis loss and low temperature in consideration of tensile strength and wear resistance. In consideration of properties, naphthenic or paraffinic process oils may be used.

In addition, the method for producing a rubber composition for undertrade as described above, as shown in Figure 3, the raw rubber mixture manufacturing step (S100) of mixing the natural rubber, the first butadiene rubber and the second butadiene, to the raw material rubber mixture It may include the step of preparing a carbon black masterbatch manufacturing step 200 to put the carbon black and mixing at a temperature of 120 ℃ to 150 ℃ and the additives to the carbon black masterbatch to prepare a rubber composition for undertrade.

The raw rubber mixture manufacturing step is to prepare a raw rubber mixture by mixing a natural rubber and the first butadiene rubber primary rubber mixture manufacturing step (S110), and after the addition of a second butadiene rubber to the primary rubber mixture Including the step (S120), the natural rubber and the first butadiene rubber may be mixed first, and then the second butadiene rubber may be further mixed to prepare a raw material rubber mixture in which the second butadiene rubber particles are effectively dispersed.

The primary rubber mixture manufacturing step (S110), the natural rubber and the first butadiene rubber in a mixer and mixed for 1 minute to 2 minutes, the step of preparing the raw material rubber mixture (S120) is the primary rubber mixture and agent It is preferable to put 2 butadiene rubber in the mixer and mix for 3 to 4 minutes. If the total mixing time is more than 5 minutes in the raw rubber mixture manufacturing step, the mechanical properties decrease due to the breaking of the rubber molecular chain, so that the total mixing It is preferable that time is 5 minutes or less.

The raw rubber mixture manufacturing step may be mixed in a ratio of 20 to 80% by weight of the natural rubber, 10 to 40% by weight of the first butadiene rubber and 10 to 40% by weight of the second butadiene rubber.

In the carbon black master batch manufacturing step (S200), the raw material rubber mixture and carbon black are put into a mixer and mixed for 10 minutes or less at a temperature of 120 to 150 ° C. to prepare a carbon black master batch.

When the carbon black masterbatch manufacturing step (S200) outside the mixing temperature and the mixing time range of 120 to 150 ℃ carbon black is not properly dispersed or the rubber chain is broken, mechanical properties are degraded because of the problem It is preferable to satisfy the above-mentioned mixing temperature and mixing time range in order to prevent dispersibility deterioration, and more preferably, the mixing time of carbon black is 2 minutes to 3 minutes.

In the present invention, "carbon black masterbatch" means a mixture of raw material rubber and carbon black at an appropriate ratio.

In the preparing of the undertrade rubber composition (S300), the carbon black masterbatch and the additive may be added to a roll mill heated to a temperature of 80 to 100 ° C., and mixed for 2 to 4 minutes to prepare a rubber composition for the undertread. have.

During roll mill operation, heat is generated due to roll friction, so the initial roll temperature is maintained at 80 to 100 ° C, and the mixing proceeds. Similarly, when the mixing time is longer than 4 minutes, mechanical properties decrease due to cutting of the rubber chain. It is desirable to meet the mixing time ranges presented above as they occur.

Since the first butadiene rubber, the second butadiene rubber, the carbon black, and the additives are the same as those of the rubber composition for the undertread in the method of manufacturing the rubber composition for the undertread, the description thereof will be omitted.

According to the under tread composition of the present invention as described above, by applying a high-strength carbon black with a developed structure, the hardness, tensile strength and material fuel efficiency performance is improved by reducing the content of the conventional carbon black used in the past, By reducing the general carbon black content in the composition, there is an effect of improving the physical properties due to the reduction in the agglomeration of carbon black generated inside the rubber composition.

In addition, as the amount of the conventional carbon black, which is a conventionally used filler, is reduced, there is an effect of additionally securing an environment-friendly property, which enables an environment-friendly manufacturing process due to less generation of filler dust in the process.

1 is a classification graph according to specific surface area-structural development of carbon black.
Figure 2 is a schematic diagram of high carbon black particles used in the general carbon black and the undertread composition of the present invention.
3 is a flow chart of a method for producing a composition for an undertread according to an embodiment of the present invention.

On the other hand, the terms "comprise" or "add" as used herein are not to be construed as necessarily including all of the various components or steps described in the specification, some of the components or It is to be understood that some steps may not be included and may further include additional components or steps.

Hereinafter, examples and comparative examples of the rubber composition for high hardness under tread of the present invention will be described in detail. These examples and comparative examples may be embodied in various different forms as one of ordinary skill in the art as an example, it is not limited to the embodiments described herein may be variously modified and changed. .

The rubber composition for the under-tread for Comparative Example 1 and Examples 1 to 9 under the conditions of the mixing temperature and the mixing time presented in the method for preparing the rubber composition for undertread of the present invention described above with the components and contents shown in Table 1 below. Prepared.

In the following table, 'NR' is natural rubber (Natural rubber), foreign matter content of 0.2% by weight natural rubber or modified natural rubber, and 'BR (1)' first butadiene rubber as cis-1,4 (cis-1,4 ) Is a polybutadiene rubber having a binding content of 90% by weight or more, and 'BR (2)' is a second butadiene rubber, having a regular syndiotactic structure based on a total of 100 parts by weight of diene rubber. Polybutadiene rubber containing 10 to 50 parts by weight of polybutadiene (syndiotactic 1,2-polybatadiene) particles, and high rigid carbon black has a dibutyl phthalate (DBT) oil absorption of 170 to 200 ml / 100 g and a nitrogen ratio. The carbon black having a surface area adsorption amount of 30 to 50 m ² / g, the general carbon black is a general-purpose carbon black having a dibutyl phthalate (DBT) oil absorption of 80 to 110 ml / 100g, the additive is used in the rubber composition for under tread Other vulcanizers needed, zinc oxide, stearic acid, aging Inhibitor, process oil, and the like.

In addition, in the following Table 1 'parts by weight' of the filler and additives is a value calculated by calculating the amount of each additive and additives 100 parts by weight of the raw material rubber.

In addition, in Table 1, the mixing conditions are the total mixing time in the rubber composition for the undertrade of the present invention, Comparative Example 1 and Examples 1 to 6 are 10 minutes or less, Example 7 has a total mixing time of 10 The mixing time is more than 20 minutes and less than 20 minutes, the mixing time of the first rubber mixture manufacturing step (S110) of mixing the natural rubber and the first butadiene rubber of the first step 7 minutes of Example 8, and finally the ' The second step mixing temperature 90 ℃ 'is the case where the mixing process is changed to 90 ℃ in the mixing conditions in the step (S120) to prepare a raw material rubber mixture by adding the second butadiene rubber to the first rubber mixture and then mixed. .

division - Change BR type and content Carbon black type and content change Change of compounding process conditions Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Raw material rubber
(weight%) NR 40 40 40 40 40 40 40 40 40 40 BR (1) 60 30 - 30 30 30 30 30 30 30 BR (2) - 30 60 30 30 30 30 30 30 30 Filler
(Part by weight) High Rigidity Carbon Black - - - - 30 10 65 30 30 30 Normal
Carbon black 45 45 45 35 - - - - - - additive
(Part by weight) Vulcanizing agent (S) 3 3 3 3 3 3 3 3 3 Zinc oxide 5 5 5 5 5 5 5 5 5 Stearic acid 5 5 5 5 5 5 5 5 5 Anti-aging 4 4 4 4 4 4 4 4 4 Process oil 6 6 6 6 6 6 6 6 6 Mixed condition 10 minutes 10 minutes 10 minutes 10 minutes 10 minutes 10 minutes 10 minutes More than 10 minutes
20 minutes or less Step 1 7 minutes 2 stage mixing temperature 90 ℃

The physical properties of the following items were evaluated for the physical properties of the rubber composition for the detrade prepared in Comparative Examples and Examples, and the results are shown in Table 2 below.

Specifically, the weather strip rubber composition of the present invention was prepared for the test of the physical properties of the sheet-shaped specimens each 2 mm thick, the hardness of the rubber composition was measured by Shore A (shore A) hardness meter, tensile strength, elongation and 100% The modulus at the time of stretching (hereinafter referred to as 'M100') was evaluated by a universal testing machine according to the method of ASTM D412, and the viscoelastic property, tanδ physical property, was measured at 10 Hz and 0.1% using DMTA (Dynamic Mechanicl Thermal Analysis) equipment. Temperature was measured at a temperature sweep of 2 ° C./min in the range of 0 ° C. to 60 ° C., and 'tanδ @ 60 ° C.' is a measure of the fuel efficiency of tire rubber material as a tanδ value at 60 ° C. The lower this value, the lower the tire rolling resistance coefficient (RRc) and the better the fuel economy.

division Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Hardness (shore M) 56 68 74 69 70 50 79 53 54 56 Tensile strength (kg / cm2) 169 169 180 170 172 151 193 142 153 147 Elongation (%) 420 371 362 398 400 355 351 350 372 360 M100 (kg / cm ² ) 30 43 55 43 43 31 58 22 25 23 tanδ @ 60 ℃ 0.074 0.087 0.111 0.073 0.070 0.065 0.125 0.120 0.105 0.113

Comparative Example 1 is a general formulation without mixing the second butadiene rubber, and Example 1 is a case where the first butadiene rubber and the second butadiene rubber are mixed at a mixing ratio of 1: 1, and when the second butadiene rubber is applied, the comparative example It was confirmed that the hardness physical properties were significantly improved compared to 1, and mechanical properties such as modulus (M100) were also improved. However, in Example 1, since the general carbon black content is the same level as in Comparative Example 1, it can be confirmed that the fuel efficiency (tanδ @ 60 ° C.) of the material decreases due to the increase in the content of the filler.

When applying only the second butadiene rubber as a whole as in Example 2 it can be seen that the properties are excessively increased compared to Comparative Example 1 and various physical properties such as elongation and material fuel economy performance is reduced, the application of only the second butadiene rubber Inadequacy can be seen.

As shown in Example 3, when the first butadiene rubber and the second butadiene rubber are mixed at an appropriate level at a mixing ratio of 1: 1, and the general carbon black content is reduced to 35 parts by weight based on 100 parts by weight of the raw material rubber, high hardness properties It was confirmed that the tensile strength, elongation, and modulus values were maintained at an appropriate level, and the fuel efficiency of the material was also satisfied at a similar level when compared with Comparative Example 1.

However, when the high stiffness carbon black is applied as in Example 4, the tensile strength, elongation and modulus properties may be improved while reducing the content of the general carbon black in addition to that of Example 3, and at the same time, the material fuel efficiency may be improved. Therefore, it is possible to secure a rubber composition for undertread that can improve the high rigidity and further fuel efficiency through the composition as in Example 4, which can be further improved to the optimum physical properties and fuel efficiency.

Example 5 and Example 6 is a rubber composition for undertread out of the appropriate content range of 10 parts by weight and 65 parts by weight of the high rigid carbon black content, respectively. When the high stiffness carbon black is less than 20 parts by weight as in Example 5, the reinforcement improvement by the carbon black is not properly performed due to the low content, so that all the measured mechanical properties such as hardness, tensile strength, elongation and modulus are inadequate. It can be seen that.

In addition, when the content of the highly rigid carbon black is added in excess of 60 parts by weight as in Example 6, it can be seen that the mechanical properties are lowered by acting as a defect of the rubber composition rather than the excessively high content of the high carbon black. In addition, when the high-strength carbon black is added in an amount exceeding an appropriate range or more, the carbon black is not dispersed and aggregated so that an excessive additive acts as a defect of the rubber composition, thereby deteriorating mechanical properties.

Examples 7 to 9 are rubber compositions for under tread manufactured by changing the mixing conditions in the same composition as in Example 4. When the total mixing time is more than 10 minutes as in Example 7 and Example 8, it can be seen that the rubber molecular chain is cut and the mechanical properties are lowered. In addition, as in Example 9, a raw material rubber mixture is prepared in which carbon black is mixed. When the mixing temperature in the step (S120) out of the appropriate range of 120 to 150 ℃ mixed at 90 ℃ temperature it can be seen that the carbon black is not evenly dispersed due to the low temperature mechanical properties and material fuel economy performance is reduced.

The specific techniques described above are merely preferred embodiments, and are not limited to the foregoing examples and the accompanying drawings. Accordingly, various substitutions and changes may be made without departing from the spirit of the present invention.

Claims (20)

Based on 100 parts by weight of the raw material rubber including 20 to 80% by weight of natural rubber, 10 to 40% by weight of the first butadiene rubber, and 10 to 40% by weight of the second butadiene rubber,
Rubber composition for undertrade, comprising 20 to 60 parts by weight of carbon black. The method of claim 1,
The first butadiene rubber is a rubber composition for undertrade, characterized in that the polybutadiene rubber having a cis-1,4 (cis-1,4) bond content of more than 90% by weight. The method of claim 1,
The second butadiene rubber comprises 10 to 50 parts by weight of syndiotactic 1,2-polybutadiene particles having a regular syndiotactic structure based on 100 parts by weight of the total diene rubber. Rubber composition for undertrade, characterized in that. The method of claim 1,
The carbon black has a rubber composition for undertrade, characterized in that the oil absorption of dibutyl phthalate (DBT) is 170 to 200 ml / 100g. The method of claim 1,
The carbon black is a rubber composition for undertrade, characterized in that the nitrogen specific surface area adsorption amount is 30 to 50 m ² / g. The method of claim 1,
The rubber composition for undertrade,
The rubber composition for undertrade, characterized in that it comprises an additive in an amount of 10 to 30 parts by weight based on 100 parts by weight of the raw material rubber. The method of claim 6,
The additive is a rubber composition for undertrade, characterized in that any one or more selected from a vulcanizing agent, a vulcanization accelerator, a galvanizing agent, a stearic acid antioxidant, an antioxidant and a process oil. A raw rubber mixture manufacturing step of mixing natural rubber, first butadiene rubber and second butadiene;
Carbon black master batch production step of mixing the carbon black in the raw material rubber mixture at a temperature of 120 ℃ to 150 ℃; And
And adding an additive to the carbon black masterbatch to prepare a rubber composition for undertrade. The method of claim 8,
The raw rubber mixture manufacturing step
Preparing a primary rubber mixture for mixing natural rubber and first butadiene rubber; And
And adding a second butadiene rubber to the primary rubber mixture, followed by mixing, to prepare a raw rubber mixture. The method of claim 9,
The primary rubber mixture manufacturing step,
A natural rubber and the first butadiene rubber in a mixer, and mixed for 1 minute or less, characterized in that the rubber composition for undertrade. The method of claim 9,
The step of preparing the raw material rubber mixture is a rubber composition for undertrade, characterized in that the first rubber mixture and the second butadiene rubber in a mixer for 3 to 4 minutes to mix. The method of claim 8,
The raw rubber mixture manufacturing step,
20 to 80% by weight of the natural rubber, 10 to 40% by weight of the first butadiene rubber and 10 to 40% by weight of the second butadiene rubber, a method for producing a rubber composition for undertrade. The method of claim 8,
The first butadiene rubber is a method for producing a rubber composition for undertrade, characterized in that the cis-1,4 (cis-1,4) bond content of more than 90% by weight polybutadiene rubber. The method of claim 8,
The second butadiene rubber may include 10 to 50 parts by weight of syndiotactic 1,2-polybutadiene particles having a regular syndiotactic structure based on 100 parts by weight of the total diene rubber. A method for producing a rubber composition for undertrade, characterized in that. The method of claim 8,
The carbon black master batch manufacturing step,
Putting the raw material rubber mixture and carbon black in a mixer, the method for producing a rubber composition for undertrade, characterized in that for mixing for 2 to 3 minutes at a temperature of 120 to 150 ℃. The method of claim 8,
The carbon black has a dibutyl phthalate (DBT) oil absorption amount of 170 to 200 ml / 100g, characterized in that the rubber composition for the undertrade. The method of claim 8,
The carbon black has a nitrogen specific surface area adsorption amount of 30 to 50 m ² / g The rubber composition for undertrade, characterized in that. The method of claim 8,
Preparing the rubber composition for undertrade,
The carbon black masterbatch and the additive in a roll mill heated to a temperature of 80 to 100 ℃ temperature, the method for producing a rubber composition for undertrade, characterized in that for mixing for 2 to 4 minutes. The method of claim 8,
The additive is a method for producing a rubber composition for undertrade, characterized in that the additive is any one or more selected from among vulcanizing agents, vulcanization accelerators, galvanizing agents, stearic acid antioxidants, antioxidants and process oils. The method of claim 8.
The additive is a rubber composition for the undertrade, characterized in that it comprises 10 to 30 parts by weight based on 100 parts by weight of the raw material rubber.

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