KR20050115084A - Silica filled rubber composition including amine based compatibilizer - Google Patents

Abstract

The present invention relates to a silica-filled rubber composition comprising an amine-based compatibilizer, and more particularly, to a silica-filled rubber composition including an amine-based compatibilizer capable of increasing dispersibility of silica and improving processability by adding an amine-based compatibilizer. It is about.

Description

Silica-filled rubber composition comprising an amine-based compatibilizer {SILICA FILLED RUBBER COMPOSITION INCLUDING AMINE BASED COMPATIBILIZER}

The present invention relates to a silica-filled rubber composition comprising an amine-based compatibilizer, and more particularly, to a silica-filled rubber composition including an amine-based compatibilizer capable of increasing dispersibility of silica and improving processability by adding an amine-based compatibilizer. It is about.

Many conventional rubber products have developed and introduced various fillers having higher performance than conventional carbon black as reinforcing agents in order to obtain better physical properties than conventional properties. Particularly, in the case of existing carbon black, oil is used as a raw material, which is regarded as a material causing environmental pollution. In the manufacture of many products that use it, various reinforcing agents can be replaced with silica and functional nano fillers. To study.

Unlike carbon black, silica has a silanol group having a hydroxyl group bonded to the silica surface to bind or adsorb about 5 to 10% of water, and has high polarity and hydrophilicity. Accordingly, the miscibility with nonpolar rubber is worse than that of carbon black, the interaction with rubber is weak, and the cohesiveness of the filler-filler is strong, which is very disadvantageous in terms of processability.

In particular, unvulcanized rubber containing silica has disadvantages such as an increase in viscosity and a significant decrease in dispersibility. In order to overcome these disadvantages of silica, the silica particle size should be small and the specific surface area should be large. The silica surface may be modified to promote low compatibility between the silanol groups and hydrophilic silica particles and the hydrophobic rubber matrix. It has been suggested that the hydrophobic modifications by physical and chemical methods should improve the compatibility between the silica and rubber matrices. In addition, in order to improve the processability and dispersibility of the silica by changing and modifying the properties of the silica, the interaction between the chemical composition of the rubber compound and the reinforcing material, the reaction between the filler and the rubber, and the physical properties have been studied.

In addition, the conventional silica dispersant improves processability by lowering the viscosity and hardness of the rubber compound mainly in the form of Zn-K soap, but has an disadvantage of promoting the aging of the rubber compound because it contains an alkali metal. In addition, it is thought that this phenomenon is induced by inducing rubber intermolecular slippage because it is a soap type, rather than improving hardness and viscosity by improving silica dispersion.

The present invention is to improve the above problems, an object of the present invention is to provide a silica-filled rubber composition added with an amine compatibilizer in order to increase the interaction and uniform dispersibility between rubber and silica and to improve processability will be.

The silica-filled rubber composition of the present invention is characterized in that it comprises 30 to 80 phr of silica and 2 to 5 phr of an amine compatibilizer with respect to 100 phr of the raw rubber.

The raw material rubber used in the present invention is not particularly limited in its kind, but a mixed rubber of natural rubber and synthetic rubber is suitable, for example, ethylene propylene diene polymer / natural rubber, hereinafter, EPDM / NR), in which case the ratio of EPDM and NR is 20-40: 80-60, especially 30:70. When the EPDM is in the above range, anti-aging characteristics, crack resistance, and aging resistance can be obtained. In addition, the EPDM is preferably composed of 70 to 75% by weight of ethylene and 9 to 11% by weight of diene, and in the case of NR, the CIS content is preferably 98% or more as maleic acid.

As an example of the silica used in the present invention, zeosil-175 is preferably used 30 ~ 80phr. The silica zeosil-175 is preferable because it has micropores on the silica surface in physical properties, and when the amount of the silica zeosil-175 is out of the above range, it tends to be disadvantageous in terms of dispersibility and processability in rubber. The silica has a surface area measured by CTAB (cetyltriammonium bromide) method is 120 ~ 140㎡ / g, and another measurement method is a numerical value measured by adsorbing the amount of oil to the silica using DOP (dioctylphthlate) Is in the range of 190 to 210 cc / 100 g.

The amine compatibilizer used in the present invention can be produced by, for example, reacting monoethanolamine with a polyhydric organic acid in a 1: 1 ratio. At this time, it is preferable to use paratoluenesulfonic acid as a catalyst. As the polyvalent organic acid, fumaric acid, maleic hydride, isophthalic acid, adipic acid, sebacic acid and the like are preferable. The amine-based compatibilizer is preferably added 2 ~ 5phr, if the amount is less than 2phr is not effective, if it exceeds 5phr it is not preferable because the aging characteristics due to oxidation worsens.

The amine compatibilizer used in the present invention does not induce chemical bonding between silica and rubber like SI-69, which is a coupling agent, but induces weak physical bonding between silica and rubber during silica blending, thereby improving dispersibility. It is considered to be.

To the rubber composition of the present invention, additives for conventional rubber compositions, such as coupling agents, paraffin oil, stearic acid, antioxidants, zinc oxide, vulcanizing agents, vulcanization accelerators and the like, may be appropriately selected and added. Their selection and usage are known in the art.

Hereinafter, the present invention will be described in more detail with reference to the following Examples and Comparative Examples. The following examples are merely examples for illustrating the present invention and are not intended to limit the protection scope of the present invention.

Examples and Comparative Examples

Table 1 shows the compositions of the rubber compositions of Examples and Comparative Examples, and the effect range according to the amine compatibilizer content in the Example compared to the Comparative Example was set.

According to the composition shown in Table 1, each component was combined to prepare a rubber composition.

More specifically, first, EPDM / NR, silica (zeosil-175), zinc oxide (ZnO), stearic acid, anti-aging agent (HPPD), wax, paraffinic oil, pressure-sensitive adhesive (POP) and amine compatibilizer in one step Carbon blending mixing step was performed. This was done using a half-barrier mixer in accordance with basic compounding conditions ASTM D3184-80. At this time, the mixing conditions were blended at the initial 100 ℃, the final 160 ℃ at a speed of 40rpm, the rubber was blended for 30 seconds in advance and the silica was added to the other additives at 110 ℃ mixed for 4 minutes at 30rpm to prepare a carbon blend. The obtained carbon blend was allowed to stand for 24 hours and then sulfur, vulcanization accelerator CZ and DPG were added to the primary carbon blend in the same mixer and mixed for 1 minute at 100 ° C. under the same conditions as the initial conditions to prepare a rubber composition. At this time, in order to stabilize the elastic behavior of the rubber, it was sufficiently left for 24 hours at room temperature to consider the thermal stability. The final crosslinking point was obtained at 160 ° C. using a rheometer. Based on this, 5 minutes was added to prepare a specimen by applying a pressure of 500 PSI using a high pressure plate heater.

The amine compatibilizer used above was prepared as follows.

Monoethanolamine and polyhydric organic acid were dissolved in normal hexane in a 1: 1 ratio and refluxed for 5 hours to terminate the first reaction. At this time, PTSA (paratoluenesulfonic acid) was used as a catalyst. After the reactor was cooled to room temperature, the solution was transferred to a separatory funnel and water was added to remove the catalyst. After the reaction solution was left to separate the layers, the water layer was completely removed and Na ₂ SO ₄ was added to dry the organic layer, and the mixture was allowed to stand for 2 hours. Then, Na ₂ SO ₄ was removed by filtering, and normal hexane was removed by distillation under reduced pressure. A phenolic resin was added thereto and reacted at 140 ° C. for 2 hours to terminate the reaction to prepare an amine compatibilizer. The product was confirmed by FT-IR, and the results showed that monoethanolamine and polyorganic acid reacted well.

The prepared specimens were compared and evaluated for rubber properties and processability, and the results are shown in Tables 2 and 3. In particular, the dispersion degree of silica was observed through EPMA-1400 (ELECTRON PROBE MICRO ANALYZER, SHIMADZU, Japan), and SI-MAPPING was performed.

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1) SMR 5CV: Standard maleic rubber

2) Amine compatibilizer: 1: 1 reactant of monoethanolamine with fumaric acid (catalyst: PTSA)

3) HPPD: N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine

4) DPG: Diphenylene Guanidine

As can be seen in Table 2, in Examples 1 and 2 to which the amine compatibilizer is added compared to Comparative Example 1, the dispersibility and physical properties were improved, and the physical properties of the initial and post-aging were substantially maintained. It became. In addition, it was shown that the growth rate is suppressed in the flex crack resistance characteristics compared to Comparative Example 2 due to the uniform dispersion and strong binding force. It also showed an advantageous trend in rheological behavior and viscoelastic properties.

As shown in Table 3, the rubber composition including the amine compatibilizer of the embodiment also showed an advantage in terms of processability and properties compared to the comparative example, which is shown to be bizarre in viscosity reduction and uniform dispersibility.

As can be seen from the above, the silica filled rubber composition including the amine compatibilizer prepared according to the present invention has remarkably improved the dispersibility of silica by adding the amine compatibilizer, and is advantageous in terms of processing. The physical properties are stably improved and have an effect of not promoting rubber aging.

Claims (4)

A silica filled rubber composition comprising 30 to 80 phr of silica and 2 to 5 phr of an amine compatibilizer with respect to 100 phr of raw rubber. The silica-filled rubber composition according to claim 1, wherein the raw material rubber is a mixed rubber of ethylene propylene diene terpolymer and natural rubber. The silica-filled rubber composition according to claim 1, wherein the amine compatibilizer is prepared by reacting monoethanolamine with a polyhydric organic acid in a 1: 1 ratio using paratoluenesulfonic acid as a catalyst. 5. The silica-filled rubber composition according to claim 4, wherein the polyvalent organic acid is fumaric acid, maleic hydride, isophthalic acid, adipic acid, or sebacic acid.