CN113278207A

CN113278207A - Rubber material of tire tread rubber containing liquid reclaimed rubber and preparation method thereof

Info

Publication number: CN113278207A
Application number: CN202110374603.8A
Authority: CN
Inventors: 戈风行; 史金炜; 张珠珠; 田卫东; 韩磊
Original assignee: Suqian Lvjinren Rubber & Plastic Machinery Co ltd
Current assignee: Suqian Lvjinren Rubber & Plastic Machinery Co ltd
Priority date: 2021-04-08
Filing date: 2021-04-08
Publication date: 2021-08-20

Abstract

The invention provides a tire tread rubber material containing liquid reclaimed rubber and a preparation method thereof. The tire tread rubber sizing material containing the liquid reclaimed rubber comprises the following raw materials in parts by weight: 50-70 parts of natural rubber, 15-30 parts of styrene-butadiene rubber, 20-40 parts of liquid reclaimed rubber, 25-40 parts of carbon black, 1-15 parts of white carbon black, 0.2-3.0 parts of silane coupling agent, 3.0-6.0 parts of anti-aging agent, 3.0-5.0 parts of zinc oxide, 1.0-3.0 parts of stearic acid, 0.1-0.3 part of anti-scorching agent, 1.0-2.0 parts of sulfur and 1.0-3.0 parts of accelerator. The liquid reclaimed rubber is prepared by taking the commonly-used environment-friendly aromatic oil of the tire rubber as a softening agent, the liquid reclaimed rubber is added into the tire tread rubber, and is used as a plasticizer, the using amount of carbon black can be reduced, partial functions of adding the liquid rubber can be realized, various indexes of the rubber can meet the requirements of the tire tread rubber, and the raw materials and the processing cost are saved.

Description

Rubber material of tire tread rubber containing liquid reclaimed rubber and preparation method thereof

Technical Field

The invention relates to a rubber material of a tire, in particular to a tire tread rubber material containing liquid reclaimed rubber and a preparation method thereof, belonging to the technical field of tire preparation.

Background

Reclaimed rubber has become the third largest rubber class most widely used after natural and synthetic rubber. When the reclaimed rubber is used in the industry, the important concern is that the reclaimed rubber has mechanical performance indexes such as tensile strength, elongation at break, hardness and the like, for example, GB/T13460-2016 reclaimed rubber performs vulcanization test on reclaimed rubber compound according to a certain formula, and the reclaimed rubber is graded according to the mechanical performance. In fact, when the reclaimed rubber is used together with the raw rubber, the components in the reclaimed rubber are mutually influenced with various auxiliary agents in a combined formula in the mixing and vulcanizing engineering, so that the index of the reclaimed rubber in the separate test is usually of little significance. The production process of the reclaimed rubber is disjointed from the actual demand when the reclaimed rubber is used together with the raw rubber, so that the reclaimed rubber can only be used as a 'blending' rubber seed for reducing the cost, the additional value of a reclaimed rubber factory is difficult to improve, downstream factories such as tire factories do not want to use the reclaimed rubber or the addition amount of the reclaimed rubber is low when the reclaimed rubber is used, and the product performance fluctuation or the obvious process change caused by a large amount of addition is worried about.

Products incorporating reclaimed rubber are considered in the industry: (1) the large flex cracking is caused by the poor flex cracking resistance of the reclaimed rubber itself, because the internal molecular bonding force of the reclaimed rubber is weakened after the waste vulcanized rubber is reclaimed. For special products with higher requirements on flex cracking, the reclaimed rubber is used in consideration and with attention paid to the amount. (2) The factors influencing the tearing resistance are more due to poor tearing resistance, wherein the compounding agent is not uniformly dispersed, and the prepared rubber product has low physical and mechanical properties, poor aging resistance and weak tearing resistance. This is not related to the low cost preparation of high performance reclaimed rubber in reclaimed rubber industry, where the raw materials are basically various by-products, such as asphalt whose softener is actually oil, and the by-product of antioxidant preparation as activator, and their components are often complex and unstable. These adjuvants are essentially left in the reclaimed rubber, are not needed in combination with virgin rubber, especially in tire formulations, and are often considered as impurities. It is therefore of interest to combine the preparation of reclaimed rubber with downstream use.

Aromatic oil asphalt is often used as a softening agent in the production of traditional reclaimed rubber, so that the effect of swelling vulcanized rubber powder is achieved, the distance between molecular chains is increased, the acting force between the molecular chains is reduced, a regenerated activator or other substances can enter a rubber molecular network structure, and the fracture of a cross-linking bond is promoted; the high boiling point substance can be retained in the sizing material after high-temperature regeneration, and plays a role in increasing viscosity and plasticity. (Zhu Xin, Xin Xiang, Lu brilliant. reclaimed rubber [ M ] chemical industry Press, 2016.). When the tire tread rubber material is prepared, aromatic oil is used as a plasticizer to reduce the viscosity of the rubber material, and a large amount of carbon black is added to improve the mechanical property. Compared with aromatic oil asphalt, the aromatic oil asphalt has low molecular weight, better compatibility with rubber and better permeation and heat transfer effects, but is lack of high boiling point substances to remain in rubber materials, so that the produced reclaimed rubber has low product performance and high price, and is used by fresh reclaimed rubber manufacturers. The reclaimed rubber prepared from the aromatic oil has great potential when being applied to tire tread rubber materials.

In addition, the liquid rubber is a viscous liquid with a relative molecular mass of about 2000-10000 at room temperature, and can form a three-dimensional network structure through a proper chemical reaction, so as to obtain an oligomer with similar physical and mechanical properties to vulcanized rubber. The liquid rubber has the characteristics that: one is that the molecular weight should be suitably small to maintain a fluid state; secondly, the crosslinking can be generated, and the physical and mechanical properties of the crosslinked material can reach the level of vulcanized rubber. In terms of processing level, the liquid rubber can undergo chain extension or crosslinking reaction under certain conditions to realize curing molding. It can be mixed with other rubber in the course of rubber processing to play the role of plasticizing softening agent, and can be substituted for aromatic oil, at the same time, it can participate in cross-linking reaction in the course of vulcanization. Therefore, the liquid reclaimed rubber can be prepared to be applied to the tire tread rubber material by utilizing the better heat transfer effect of the aromatic oil and the waste rubber powder.

Zhang gang et al, in "method for continuously preparing liquid reclaimed rubber by screw extruder" CN102601975B, propose to crush the three-dimensional cross-linked network of waste rubber under the combined action of temperature, pressure, shear and desulfurizing agent in the extruder to obtain liquid reclaimed rubber. The regenerants used included activators and softeners: the softening agent comprises one or more of coal tar, pine tar, tall oil, naphthenic oil, dipentene, paraffin oil, oleic acid and rosin, and the activating agent is one or more of aromatic hydrocarbon disulfide, polyalkyl phenol sulfide, phenyl mercaptan and n-butylamine. The starting point is that the waste rubber powder is fully desulfurized, depolymerized and regenerated, and other regeneration methods only lie in the degree of damage of three-dimensional cross-linked networks in the waste rubber, are unconsciously used as a plasticizer in the tread rubber, do not pay attention to the content of sol (solvent is generally toluene) in the regenerated rubber, acetone extract, molecular weight and distribution thereof, and are very important to the compatibility and plasticizing effect of the regenerated rubber or regenerated liquid rubber and raw rubber.

Disclosure of Invention

The invention provides a tire tread rubber material containing liquid reclaimed rubber, which is prepared by taking environment-friendly aromatic oil in the tire rubber material as a softening agent, not only retains the plasticizing effect of the aromatic oil, but also has the advantage of reducing the cost by blending the traditional reclaimed rubber, and can play the role of liquid rubber. The adhesive is characterized by comprising the following components in parts by weight:

wherein the total parts of the natural rubber, the styrene butadiene rubber and the liquid reclaimed rubber are 100 parts.

The sol content of the preferred liquid reclaimed rubber is 50-80%, and the preparation method comprises the following steps: the waste rubber powder and the reclaiming agent are uniformly mixed, added into a screw extruder with an exhaust section through a compaction device, extruded out of the screw extruder after reacting for 1-5 min under the shearing action by controlling the temperature of different sections of the extruder to be 250-350 ℃, and water-cooled and air-dried after rubber filtering to obtain the liquid reclaimed rubber. The rubber powder is waste rubber powder which is waste tire tread rubber powder. The regenerant comprises a softener and an activator: the softener is environment-friendly aromatic hydrocarbon operating oil, and the activator is aromatic hydrocarbon disulfide; the weight ratio of the waste rubber powder to the softening agent to the activating agent is 100 (1-5) to 0.2-1.

The preferable white carbon black is high-dispersion precipitated white carbon black; the silane coupling agent is one or a mixture of silicon 747 and silicon 69.

The preferred anti-aging agent comprises anti-aging agent 4020 and anti-aging agent DTPD, wherein the anti-aging agent 4020 is 2.0-5.0 parts, and the anti-aging agent DTPD is 0.5-2.0 parts.

Preferred accelerators are accelerator NS; the scorch retarder is a scorch retarder CTP.

The preferred method of preparing the tread compound comprises the steps of:

a) first-stage mixing: adding natural rubber, styrene-butadiene rubber, liquid reclaimed rubber, zinc oxide, stearic acid, a silane coupling agent, an anti-aging agent, half of carbon black and half of white carbon black into an internal mixer, mixing for 2-4 min, discharging rubber at the temperature of 140-160 ℃, and preparing a section of master batch by a lower sheet of the internal mixer;

b) and (3) second-stage mixing: adding a section of masterbatch, the other half of carbon black and the other half of white carbon black into an internal mixer, mixing for 2-3 min, discharging the rubber at the temperature of 150-;

c) three-stage mixing: adding a section of rubber compound into an internal mixer, mixing for 50-80 seconds to 120-150 ℃ for rubber discharge, discharging pieces by using an open mill, cooling and stacking;

d) a vulcanization process: adding the three-section rubber compound, sulfur, an accelerant and an anti-scorching agent into an internal mixer, mixing for 60-80 seconds, discharging rubber from a discharging door when the temperature is 95-105 ℃, discharging sheets from the internal mixer, cooling and stacking.

In the process of preparing the liquid reclaimed rubber, as the compatibility of the environment-friendly aromatic oil and the waste rubber powder is better, the environment-friendly aromatic oil and the waste rubber powder have good permeability, the heat transfer is fast, so that the waste rubber powder is uniformly desulfurized, and the generation of hard particles and a core-shell structure is reduced under the shearing action; meanwhile, the influence of oxidation of oxygen or other auxiliaries on rubber hydrocarbon is reduced as much as possible, so that the three-dimensional network structure of most of rubber hydrocarbon is changed into short-chain hydrocarbon, and when the rubber is used together with raw rubber, the plasticizing effect similar to that of aromatic oil can be achieved. As the aromatic oil basically does not chemically react with the waste rubber powder, the components of the aromatic oil are basically kept in the liquid reclaimed rubber in the original shape, so that the components of the reclaimed rubber are relatively simple, and the influence on the formula design of the tread rubber powder is smaller.

Different from the traditional aromatic oil which only plays a role in plasticization, the liquid reclaimed rubber participates in a vulcanization reaction in the rubber material vulcanization process, and the problem that the mixed product has large deflection cracks easily caused by weakening of the internal bonding force of macromolecules caused by reclaimed rubber prepared through the traditional desulfurization process is solved. Meanwhile, as the main chain and the cross-linked bond are greatly degraded, the network structure is small, the original auxiliary agent in the waste rubber is easier to disperse when the reclaimed rubber liquid rubber and the raw rubber are used together, and the problems of poor tearing resistance and the like caused by uneven dispersion of the compounding agent when the reclaimed rubber is added are effectively reduced. Meanwhile, the rich carbon black reduces the dosage of the carbon black in the formula. The liquid reclaimed rubber not only overcomes the problem of the combination use of the traditional reclaimed rubber and the raw rubber, but also can greatly reduce the use amount of carbon black and the raw rubber. Meanwhile, compared with the traditional liquid isoprene rubber and the like, the cost for preparing the liquid reclaimed rubber is much lower, so that the cost is greatly reduced on the premise of ensuring the tire tread quality, and the social benefit and the economic benefit are remarkable.

Claims

1. The tire tread rubber material containing the liquid reclaimed rubber is characterized by comprising the following components in parts by weight:

2. The liquid regrind-containing tire tread stock according to claim 1, wherein: the sol content of the liquid reclaimed rubber is 50-80%, and the preparation method comprises the following steps: uniformly mixing the waste rubber powder and a regenerant, adding the mixture into a screw extruder with an exhaust section through a compaction device, reacting for 1-5 min under the shearing action by controlling the temperature of different sections of the extruder at 250-350 ℃, extruding the mixture from the screw extruder, filtering the mixture, and performing water cooling and air drying to obtain liquid reclaimed rubber; the rubber powder is waste rubber powder which is waste tire tread rubber powder; the regenerant comprises a softener and an activator: the softener is environment-friendly aromatic hydrocarbon operating oil, and the activator is aromatic hydrocarbon disulfide; the weight ratio of the waste rubber powder to the softening agent to the activating agent is 100 (1-5) to 0.2-1.

3. The liquid regrind-containing tire tread stock as claimed in claim 1, wherein: the white carbon black is high-dispersion type precipitation white carbon black; the silane coupling agent is one or a mixture of silicon 747 and silicon 69.

4. The liquid regrind-containing tire tread stock according to claim 1, wherein: the anti-aging agent is composed of anti-aging agent 4020 and anti-aging agent DTPD, wherein the anti-aging agent 4020 is 2.0-5.0 parts, and the anti-aging agent DTPD is 0.5-2.0 parts.

5. The liquid regrind-containing tire tread stock according to claim 1, wherein: the accelerant is accelerant NS; the scorch retarder is a scorch retarder CTP.

6. The liquid regrind-containing tire tread compound of claim 1, wherein the process comprises the steps of:

b) and (3) second-stage mixing: adding a first section of masterbatch, the other half of carbon black and the other half of white carbon black into an internal mixer, mixing for 2-3 min, discharging rubber at the temperature of 150-;

c) three-stage mixing: adding the two-stage rubber compound into an internal mixer, mixing for 50-80 seconds to 120-150 ℃ for rubber discharge, discharging pieces by using an open mill, cooling and stacking to obtain three-stage rubber compound;