KR102389823B1 - Silica-rubber composite composition containing cellulose derivative dispersant and method for producing the same - Google Patents

Abstract

The present invention is silica; cellulose derivative dispersants; and a silica-rubber composite composition in which a rubber raw material is mixed, and a method for preparing the same. The possibility of use as a rubber composite material having excellent processability, tensile properties and abrasion properties was confirmed by the addition of a cellulose derivative dispersant.

Description

Silica-rubber composite composition containing cellulose derivative dispersant and method for producing the same

The present invention relates to a silica-rubber composite composition having improved silica dispersibility by applying a cellulose derivative as a dispersant and a method for preparing the same.

Silica is used as an indispensable material in a wide range of fields. Among them, silica is used to improve the reinforcing properties of rubber as a filler in rubber and has hydrophilic properties that adhere well to water. Therefore, it can improve the braking performance of the tire on a wet road surface, so it is widely used in the recently released ultra-high performance tires.

However, since silica has silanol groups on the surface, hydrogen bonds between silicas occur due to silanol groups on the surface of silica, and synthetic rubber is hydrophobic, so it does not mix well with each other. For this reason, there is a problem in that silica dispersibility is poor in the silica-rubber composite material and aggregation of silica occurs.

This silica agglomeration phenomenon adversely affects the physical properties of the rubber composite material. In order for the silica-rubber composite material to exhibit excellent properties, the silica in the rubber must be evenly dispersed. In order to improve the dispersion of silica, it is necessary to hydrophobize the silica surface, develop a rubber having a polar group, and develop a dispersant for silica.

As a result of intensive research efforts to solve the problem of silica agglomeration and improve the physical properties of the silica-rubber composite composition, the present inventors confirmed that silica dispersibility as well as processability and abrasion resistance are improved by applying a cellulose derivative to the rubber composition as a silica dispersant, and The present invention was completed.

One object of the present invention is to provide a silica-rubber composite composition in which silica and a cellulose derivative dispersant, and a rubber raw material are mixed.

Another object of the present invention is a first step of preparing a mixture by stirring silica, a cellulose derivative dispersant, and a rubber raw material; and a second step of adding a coagulant to the mixture, to provide a method for preparing a silica-rubber composite composition.

This will be described in detail as follows. Meanwhile, each description and embodiment disclosed in the present invention may be applied to each other description and embodiment. That is, all combinations of the various elements disclosed herein fall within the scope of the present invention. In addition, it cannot be considered that the scope of the present invention is limited by the specific descriptions described below.

A first aspect of the present invention is to provide a silica-rubber composite composition in which silica, a cellulose derivative dispersant, and a rubber raw material are mixed.

The "silica" of the present invention may mean a reinforcing filler used in manufacturing rubber including tires. Silica can improve fuel efficiency by reducing the rolling resistance of rubber, and can also improve braking performance. However, silica has a problem in that it is difficult to interact with a hydrophobic rubber due to a silanol group on the surface, and silica dispersibility is deteriorated due to aggregation caused by hydrogen bonding between silicas. A separate silica dispersant is required to solve this problem.

It is most preferable that the silica has a particle size of 0.1 um to 100 um in terms of dispersion stability and anti-blocking.

The "silica" used in the present invention includes Ultrasil 7000Gr ^TM (manufactured by Evonik), Ultrasil 9000Gr ^TM (manufactured by Evonik), Zeosil 1165MP ^TM (manufactured by Rhodia), Zeosil 200MP ^TM (manufactured by Rhodia) or Zeosil 195HR ^TM (manufactured by Rhodia), etc. Commercial products of may be used, but is not limited thereto.

The "cellulose derivative dispersant" of the present invention means a silica dispersant as a cellulose-based resin. Specifically, it refers to a resin represented by the following formula (1).

[Formula 1]

Wherein R is provided with a hydrophilic functional group capable of hydrogen bonding,

Specifically, R is an alkyl group substituted with a hydrophilic functional group capable of hydrogen bonding, the alkyl group is C1 to C5, and the hydrophilic functional group is a hydroxyl group (-OH), a carboxyl group (-COOH), a thiol group (-SH) and It is any one selected from the group consisting of an amine group (NH ₂ ). In an embodiment of the present invention, methanol (CH ₃ OH) and acetic acid (CH ₃ COOH) were used, but the present invention is not limited thereto.

For example, an alcohol group or a carboxyl group that is the polar functional group may react with a silanol group of silica to make the silica surface hydrophobic. When the number of carbons is more than 5, there is a problem in that intermolecular bonding with silica is not sufficient due to hydrogen bonding in the cellulosic resin.

The cellulose derivative dispersant may be used in an amount of 2 to 5 parts by weight based on 100 weight of the rubber raw material. If it is less than 2, the effect as a silica dispersant is insignificant, and if it is more than 5, silica dispersibility is improved and the viscosity of rubber is lowered to improve processability, but the activity of the vulcanization accelerator CBS (N-cyclohexylbenzothiazole) Hydrogen bonding may interfere with the degradation of mechanical properties and wear resistance.

The "rubber raw material" of the present invention includes at least one or more from the group consisting of styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, butadiene rubber, ethylene-propylene rubber, and neodymium butadiene rubber. may be doing

The amount of the silica may be 80 to 120 parts by weight based on 100 parts by weight of the rubber raw material. When it is within the above range, it may have an excellent effect as a rubber reinforcing material.

A second aspect of the present invention is a first step of preparing a mixture by stirring silica, a cellulose derivative dispersant, and a rubber raw material; and a second step of adding a coagulant to the mixture, to provide a method for preparing a silica-rubber composite composition.

In the first step of the present invention, the reaction is performed at 50° C. or higher to prevent layer separation between silica and rubber raw material. In this case, the silica, the cellulose derivative dispersant, and the solvent that can be used for the rubber raw material are water-based solvents, specifically water, methanol, ethanol, and the like, but are not limited thereto. More specifically, it may be water.

The second step refers to a step for preparing the agglomerated silica-rubber composite composition. The coagulant may include, but is not limited to, calcium chloride, sulfuric acid, hydrochloric acid, magnesium sulfate, aluminum sulfate, and the like.

The present invention may include the step of adding at least one or more from the group consisting of an activator, an antioxidant, a vulcanizing agent, and a vulcanization accelerator after the second step. In one comparative example and embodiment of the present invention, ZnO (zinc oxide) as the activator, 6PPD (N-dimethylbutyl-N'-phenyl-P-phenylenediamine) as the antioxidant, sulfur as the vulcanizing agent, the CBS (N-cyclohexylbenzothiazole) and DPG (N,N-diphenylguanidine) were used as vulcanization accelerators, but the present invention is not limited thereto.

The silica-rubber composite composition prepared by adding a cellulose derivative dispersant has improved silica dispersibility and thus improved processability, tensile properties, and abrasion resistance, so that it can be widely used in various rubber composite materials using silica.

Hereinafter, the present invention will be described in more detail by way of Examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Comparative Example 1. Preparation of silica-rubber composite composition

Silica was stirred in a reactor using water as a solvent, and SBR latex ¹⁾ 100 phr was added. At this time, to prevent layer separation, the mixture was maintained at 60° C. or higher and stirred for a certain period of time. After that, a coagulant was added to the mixed solution while stirring to obtain an agglomerated silica-SBR composite, which was dried for at least 24 hours. The dried silica-SBR composite material was treated with a Kneader group using 3 phr of ZnO (zinc oxide) as an activator, 2 phr of stearic acid as a stabilizer, and 6PPD (N-dimethylbutyl-N'-phenyl-P-phenylenedia as an antioxidant). Min) 1 phr, vulcanizing agent 1.5 phr sulfur, vulcanization accelerator CBS (N-cyclohexylbenzothiazole) 1.5 phr and DPG (N,N-diphenylguanidine) 1.5 phr were added and mixed. Then, it was made into a sheet using a roll mill and vulcanized at 160° C. for a certain period of time under vulcanization conditions using a rheometer, and then molded to a suitable standard and used for the test. The SBR latex ¹⁾ refers to Styrene-Butadiene-Rubber latex in the form of an emulsion.

Example 1.

A rubber was prepared in the same manner as in Comparative Example 1, except that 4 phr of the cellulose derivative dispersant was used. The "cellulose derivative dispersant" refers to a silica dispersant as a cellulose-based resin. Specifically, it refers to a resin represented by the following formula (1).

[Formula 1]

Wherein R is H means a cellulose derivative dispersant.

Example 2.

A rubber was prepared in the same manner as in Comparative Example 1, except that 4 phr of the cellulose derivative dispersant was used. The "cellulose derivative dispersant" refers to a silica dispersant as a cellulose-based resin. Specifically, the resin represented by Formula 1, wherein R is C ₂ OH means a cellulose derivative dispersant.

Example 3.

A rubber was prepared in the same manner as in Comparative Example 1, except that 4 phr of the cellulose derivative dispersant was used. The "cellulose derivative dispersant" refers to a silica dispersant as a cellulose-based resin. Specifically, it is a resin represented by Formula 1, and R is CH ₂ COOH means a cellulose derivative dispersant.

Example 4. A silica-rubber composite composition was prepared in the same manner as in Example 1, except that 2 phr of the cellulose derivative dispersant was used.

Comparative Example 2. A silica-rubber composite composition was prepared in the same manner as in Example 1, except that 6 phr of the cellulose derivative dispersant was used.

Comparative Example 3. A silica-rubber composite composition was prepared in the same manner as in Example 1, except that 40 phr of silica was used.

Comparative Example 4. A silica-rubber composite composition was prepared in the same manner as in Example 1, except that 60 phr of silica was used.

Example 5. A silica-rubber composite composition was prepared in the same manner as in Example 1, except that 80 phr of silica was used.

Example 6. A silica-rubber composite composition was prepared in the same manner as in Example 1, except that 120 phr of silica was used.

Table 1 below summarizes the composition ratio of the silica-rubber composite composition of Comparative Examples 1 to 4 and Examples 1 to 6 above.

Rubber formulation table (unit: phr) division SBR Latex ¹⁾ silica Cellulose derivative dispersant content Cellulose derivatives Dispersant Functional Group Types Comparative Example 1 100 100 - - Example 1 100 100 4 H Example 2 100 100 4 C ₂ OH Example 3 100 100 4 CH ₂ COOH Example 4 100 100 2 H Comparative Example 2 100 100 6 H Comparative Example 3 100 40 4 H Comparative Example 4 100 60 4 H Example 5 100 80 4 H Example 6 100 120 4 H

SBR latex ¹⁾ in Table 1 means Styrene-Butadiene-Rubber latex in the form of an emulsion, and cellulose derivative dispersant ²⁾ means cellulose having the structure of Formula 1 above.

Experimental Example 1. Method for evaluating physical properties of silica-rubber composite composition by type of cellulose derivative dispersant

Mooney viscosity indicating workability was measured using the MV2020 model of Myongji Tech Co., Ltd. and the value of (ML(1+4)@100℃ according to the ISO 289-1 standard. Tensile properties are the H5K-T model of Tinius Olsen. It was measured using a universal testing machine (UTM) tensile tester.The sheet made by molding in a press was cut into a specimen for measuring physical properties according to KSM 6518, and then tensile strength and elongation were measured. Abrasion was measured according to ASTM D 5963. Diameter according to ASTM D 5963 A 16 mm, 8 mm thick cylindrical specimen was manufactured, and the specimen was abraded 40±0.2 m on the surface of abrasive cloth attached to a cylindrical drum rotating at a speed of 40±1 rpm to compare the amount of wear reduction of the specimen compared to the initial specimen weight. The weight of the worn specimen was calculated and measured.The hardness was measured by measuring the specimen of 1 mm 5 times using the CL-150M model of With Lab Co., Ltd. based on the ISO 868 standard, and the average value was shown. 2 to 4 will be described.

Experimental Example 2. Evaluation of physical properties according to R group of cellulose derivative dispersant

Mooney viscosity, mechanical properties and abrasion resistance test results division Comparative Example 1 Example 1 Example 2 Example 3 Mooney
Viscosity (100℃) 93.6 90.5 91.3 90.9 Hardness 60 65 62 63 100% modulus
(kgf/cm ² ) 13.5 15.9 14.0 14.8 300% modulus (kgf/cm ² ) 42.4 50.7 44.5 48.6 Elongation (%) 1050 980 1060 1010 The tensile strength
(kgf/cm ² ) 245 262 251 258 Wear characteristics (mg) 258.5 183.8 222.3 205.6

In Table 2, the lower the Mooney viscosity value, the better the rubber processability, and the higher the hardness, the harder it is. The higher the numerical values for tensile properties (100%, 300% modulus, tensile strength, and elongation), the better each property is. In the case of abrasion characteristics, it indicates the weight lost compared to the initial weight, and the lower the number, the better the wear characteristics.

As shown in Table 2, when Comparative Example 1 and Examples 1 to 3 are compared, regardless of the type of R group (H, CH ₂ OH, CH ₂ COOH), when the cellulose derivative dispersant is added, Mooney viscosity is lowered and processability is improved. can confirm. In addition, it can be seen that mechanical properties and abrasion resistance are also improved. Among them, in particular, when R=H, an excellent effect was exhibited in terms of workability, mechanical properties, and abrasion resistance. Afterwards, Examples 4 to 9 were tested by applying the cellulose dispersant corresponding to Example 1.

Experimental Example 3. Evaluation of physical properties according to cellulose derivative dispersant content

Mooney Viscosity and Physical Properties Test Results division Comparative Example 1 Example 1 Example 4 Comparative Example 2 Mooney Viscosity (100℃) 93.6 92.9 90.5 87.2 Hardness 60 62 65 58 100% modulus (kgf/cm ² ) 13.5 15.0 15.9 12.7 300% modulus (kgf/cm ² ) 42.4 48.6 50.7 38.9 Elongation (%) 1050 1050 980 1060 Tensile strength (kgf/cm ² ) 245 250 262 236 Wear characteristics (mg) 258.5 200 183.8 214.6

As shown in Table 3, in Comparative Examples 1 and 2 and Examples 1 and 4 using the cellulose derivative dispersant, as the content of the cellulose derivative dispersant increases, the Mooney viscosity decreases, thereby improving processability. In Comparative Example 1 and Examples 1 and 4 using the cellulose derivative dispersant, when the cellulose derivative dispersant was applied up to 4 phr, it was confirmed that mechanical properties and abrasion resistance were improved. However, in Comparative Example 2, it was confirmed that processability was improved when 6 phr of the cellulose derivative dispersant was applied, but physical properties were lowered compared to Examples 1 and 2 in terms of hardness, modulus, and tensile strength. Through this, it can be inferred that the content of the cellulose derivative dispersant applied to the silica-rubber composite composition having properties equal to or higher than those of Comparative Example 1 while improving processability is less than 6 phr.

Experimental Example 4. Evaluation of physical properties according to silica content

Mooney viscosity, mechanical properties and abrasion resistance test results division Comparative Example 1 Example 1 Comparative Example 2 Comparative Example 3 Example 5 Example 6 Mooney
Viscosity (100℃) 93.6 90.5 86.7 88.3 89.9 91.4 Hardness 60 65 70 69 67 63 100% modulus
(kgf/cm ² ) 13.5 15.9 9.5 11.0 13.4 16.3 300% modulus (kgf/cm ² ) 42.4 50.7 39.7 42.3 46.5 51.5 Elongation (%) 1050 980 1070 1040 1010 940 The tensile strength
(kgf/cm ² ) 245 262 205 228 244 268 Wear characteristics (mg) 258.5 183.8 238.8 212.5 198.5 180.6

As shown in Table 4, as the silica content increased through Comparative Examples 2 and 3 and Examples 1, 5, and 6, the workability was decreased through the increase of Mooney viscosity, and it was confirmed that mechanical properties and abrasion resistance were improved. . When a high silica content is added to the existing silica-rubber composite composition, mechanical properties and abrasion resistance are deteriorated due to a decrease in dispersibility due to aggregation of silica.

However, comparing Comparative Example 1 with Examples 5 and 6, when 4 phr of a cellulose derivative dispersant is added when the silica weight is 80, 100, and 120 compared to 100 weight of SBR-latex, silica dispersibility is improved even when a high silica content is added As a result, it can be seen that mechanical properties and abrasion resistance are improved.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art or those having ordinary skill in the art will not depart from the spirit and scope of the present invention described in the claims to be described later. It will be understood that various modifications and variations of the present invention can be made without departing from the scope of the present invention.

Accordingly, the technical scope of the present invention should not be limited to the content described in the detailed description of the specification, but should be defined by the claims.

Claims (10)

delete delete delete delete delete delete A first step of preparing a mixture by stirring silica, a cellulose derivative dispersant, and a rubber raw material; and
A second step of adding a coagulant to the mixture,
The cellulose derivative dispersant is represented by the following formula (1),
[Formula 1]

Wherein R is hydrogen (H),
Wherein n is an integer of 2 or more,
2 to 5 parts by weight of the cellulose derivative dispersant is mixed with respect to 100 weight of the rubber raw material,
and vulcanizing by adding a vulcanizing agent and a vulcanization accelerator after the second step,
The method for producing a silica-rubber composite composition, wherein the silica having a hydrophobic surface by reacting the compound of Formula 1 with the silanol group of the silica in the first step is dispersed between the rubber raw material.
delete delete 8. The method of claim 7,
After the second step, the method for producing a silica-rubber composite composition comprising adding at least one or more from the group consisting of an active agent and an antioxidant.