US-12617879-B2 - Neodymium-catalyzed conjugated diene-based polymer and rubber composition comprising same

Abstract

The present invention relates to a conjugated diene-based polymer having high processability and excellent compounding properties, a preparation method thereof and a rubber composition including same, and provides a neodymium-catalyzed conjugated diene-based polymer satisfying all conditions of (a) to (c), a preparation method thereof and a rubber composition including same.

Inventors

• Sung Ho Park
• Tae Chul Lee
• Su Hwa Kim
• Dong Hui Kim

Assignees

• LG CHEM, LTD.

Dates

Publication Date

20260505

Application Date

20210924

Priority Date

20200925

Claims (8)

1. 1 . A neodymium-catalyzed conjugated diene-based polymer satisfying the following conditions (a) to (c): (a) a residual amount of a neodymium catalyst, measured by inductively coupled plasma (ICP) is from 20 to less than 45 wtppm; (b) a β-value is less than 0.20, where the β-value is a slope of a log(frequency)(x-axis)−log(1/tan δ)(y-axis) graph obtained from measured results of tan δ at 100° C. by a rubber process analyzer (RPA); and (c) the following Equation 1 is satisfied: 0.3 X +4 <Y <0.3 X +6 [Equation 1] in Equation 1, X is mooney viscosity (ML1+4, @100° C.), and Y is a ratio (%) of a number of polymer chains having a molecular weight of 1,000,000 g/mol or more based on a total number of polymer chains in a molecular weight distribution curve by gel permeation chromatography (GPC), wherein, in condition (c), X is 40 to 50.
2. 2 . The neodymium-catalyzed conjugated diene-based polymer of claim 1 , wherein, in the condition (b), the β-value is from 0.160 to 0.199.
3. 3 . The neodymium-catalyzed conjugated diene-based polymer of claim 1 , wherein the neodymium catalyst is a compound represented by the following Formula 1: in Formula 1, R a to R c are each independently hydrogen or an alkyl group of 1 to 12 carbon atoms, where R a to R c are not hydrogen, simultaneously.
4. 4 . The neodymium-catalyzed conjugated diene-based polymer of claim 3 , wherein R a is an alkyl group of 4 to 12 carbon atoms, and R b and R c are each independently hydrogen or an alkyl group of 1 to 8 carbon atoms.
5. 5 . The neodymium-catalyzed conjugated diene-based polymer of claim 1 , wherein a weight average molecular weight is 500,000 to 1,200,000 g/mol.
6. 6 . The neodymium-catalyzed conjugated diene-based polymer of claim 1 , wherein molecular weight distribution is 1.5 to 3.5.
7. 7 . A rubber composition comprising the neodymium-catalyzed conjugated diene-based polymer of claim 1 .
8. 8 . The neodymium-catalyzed conjugated diene-based polymer of claim 1 , wherein the residual amount of the neodymium catalyst is from 20 to 40 wtppm.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims the benefit of priority based on Korean Patent Application No. 10-2020-0125164, filed on Sep. 25, 2020, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD The present invention relates to a neodymium-catalyzed conjugated diene-based polymer having high processability and excellent compounding properties, and a rubber composition comprising same. BACKGROUND ART Recently, according to the growing attention on saving energy and environmental issues, the decrease of the fuel consumption ratio of cars is required. As a method for accomplishing the requirement, a method for decreasing the heating properties of tires using an inorganic filler such as silica and carbon black in a rubber composition for forming tires has been suggested. However, the dispersion of the inorganic filler in the rubber composition is not favorable, and defects of degrading overall physical properties of the rubber composition including abrasion resistance, crack resistance or processability arise. In order to solve such problems, a method of modifying the polymerization active moiety of a conjugated diene-based polymer which is obtained by anionic polymerization using an organolithium with a functional group which is capable of interacting with an inorganic filler, has been developed as a method for increasing the dispersibility of an inorganic filler such as silica and carbon black in a rubber composition. Particularly, a method of modifying the polymerization active terminal of a conjugated diene-based polymer with a tin-based compound, a method of introducing an amino group, or a method of modifying with an alkoxysilane derivative has been suggested. However, if a rubber composition is prepared using the modified conjugated diene-based polymer which has been modified by the above-described methods, low heating properties may be secured, but the improving effects of the physical properties of a rubber composition such as abrasion resistance and processability were insufficient. As another method, a method of modifying a living active terminal using a specific coupling agent or a modifier in a living polymer obtained by coordination polymerization using a catalyst including a lanthanide rare earth element compound has been developed. However, in the catalyst including the conventionally known lanthanide rare earth element compound, the activity of a living terminal produced is weak, a terminal modification ratio is low, and the improving effects of the physical properties of a rubber composition are insignificant. PRIOR ART DOCUMENT (Patent Document 1) KR 10-2020-0078405 A DISCLOSURE OF THE INVENTION Technical Problem An object of the present invention is to provide a conjugated diene-based polymer having high processability and excellent compounding properties, and a rubber composition including same. Another object of the present invention is to provide a method for preparing the conjugated diene-based polymer. Technical Solution To solve the above-described tasks, there is provided in the present invention a neodymium-catalyzed conjugated diene-based polymer satisfying all the following conditions (a) to (c): (a) a residual amount of a neodymium catalyst, measured by inductively coupled plasma (ICP) is less than 50 wtppm;(b) a β-value is less than 0.20, where the β-value means a slope of a log(frequency)(x-axis)−log(1/tan δ)(y-axis) graph obtained from measured results of tan δ at 100° C. by a rubber process analyzer (RPA); and(c) the following Equation 1 is satisfied: 0.3X+4<Y<0.3X+6  [Equation 1] in Equation 1,X is mooney viscosity (ML1+4, @100° C.), andY is a ratio (%) of a number of polymer chains having a molecular weight of 1,000,000 g/mol or more in contrast to a total number of polymer chains in a molecular weight distribution curve by gel permeation chromatography (GPC). In addition, the present invention provides a method for preparing a neodymium-catalyzed conjugated diene-based polymer, comprising: (S1) a step of polymerizing a conjugated diene-based monomer in the presence of a catalyst composition comprising a neodymium compound, and a molecular weight controller in a first reactor of 85° C. or more in a polymerization conversion ratio of 80% or more to discharge a polymer product; and (S2) a step of transporting the polymer product to a second reactor and performing polymerization, wherein the neodymium compound in the catalyst composition is 0.01 to 0.03 mmol based on 100 g of the conjugated diene-based monomer, and the molecular weight controller is 0.01 to 0.20 phm. Advantageous Effects The neodymium-catalyzed conjugated diene-based polymer of the present invention has a high degree of branching and shows excellent affinity with a filler, and if applied to a rubber composition, dispersibility is high, and excellent processability may be shown. In addition, a molded product manufactured therefrom shows excellent ph