阅读说明：本技术 丁苯橡胶的制备方法 (Preparation method of styrene butadiene rubber ) 是由 庞建勋 殷兰 赵欣 孙继德 李永茹 侯军 王秀芝 刘洪伟 石捷强 于 2019-02-14 设计创作，主要内容包括：本发明提供了一种丁苯橡胶的制备方法。该制备方法包括在环保型分子量调节剂的作用下,采用乳液聚合法制备丁苯胶乳的过程,且环保型分子量调节剂为2-巯基异丁酸硫醇酯和/或2-巯基丁酸硫醇酯。相比于现有的C<Sub>2</Sub>～C<Sub>4</Sub>羧酸的巯基烷基羧酸酯化合物,2-巯基异丁酸硫醇酯类化合物和2-巯基丁酸硫醇酯类化合物的毒性更小,且此类化合物含有两个巯基,对于分子量的调节能力更强。采用该环保型分子量调节剂制备丁苯橡胶时,聚合阶段、脱气阶段及凝聚洗涤干燥阶段均没有明显的异味,实现了环保生产,降低了对操作人员的身体损害,同时可以得到门尼粘度适中的丁苯橡胶产品。(The invention provides a preparation method of styrene butadiene rubber. The preparation method comprises the process of preparing the styrene-butadiene latex by adopting an emulsion polymerization method under the action of the environment-friendly molecular weight regulator, and the environment-friendly molecular weight regulator is 2-mercaptoisobutyric acid thiol ester and/or 2-mercaptobutyric acid thiol ester. Compared with the prior C 2 ～C 4 The mercaptoalkyl carboxylate compounds of carboxylic acid, 2-mercaptoisobutyrate mercaptan ester compounds and 2-mercaptobutyrate mercaptan ester compounds have lower toxicity, and the compounds contain two sulfydryl groups and have stronger regulation capability on molecular weight. When the environment-friendly molecular weight regulator is used for preparing butadiene styrene rubber, no obvious peculiar smell exists in the polymerization stage, the degassing stage and the condensation, washing and drying stage, environment-friendly production is realized, the body damage to operators is reduced, and butyl with moderate Mooney viscosity can be obtainedA benzene rubber product.)

1. A preparation method of styrene butadiene rubber is characterized by comprising the step of preparing styrene butadiene latex by adopting an emulsion polymerization method under the action of an environment-friendly molecular weight regulator, wherein the environment-friendly molecular weight regulator is 2-mercaptoisobutyric acid thiol ester and/or 2-mercaptobutyric acid thiol ester.

2. The method of claim 1, wherein the eco-friendly molecular weight modifier comprises one or more selected from the group consisting of isoheptylmercaptyl 2-mercaptoisobutyrate, octylmercaptyl 2-mercaptoisobutyrate, isoheptylmercaptyl 2-mercaptobutyrate, and octylmercaptyl 2-mercaptobutyrate;

preferably, the environment-friendly molecular weight regulator comprises 0.06-0.11 part of the isoheptyl 2-mercaptoisobutyrate and 0.06-0.11 part of the octyl 2-mercaptoisobutyrate.

3. The method according to claim 2, wherein the weight ratio of isoheptylmercaptyl 2-mercaptoisobutyrate to octyl 2-mercaptoisobutyrate is 1:1 to 1.5.

4. The method according to any one of claims 1 to 3, wherein the styrene-butadiene latex is prepared by a process comprising:

under the action of nitrogen, taking styrene, butadiene, water, an emulsifier, an electrolyte, a reducing agent, the environment-friendly molecular weight regulator and an initiator as raw materials to carry out emulsion polymerization reaction, and adding a terminator into a reaction system of the emulsion polymerization reaction when the conversion rate of the raw materials reaches 60% to obtain styrene-butadiene latex, wherein the temperature of the emulsion polymerization reaction is less than or equal to 5 ℃;

preferably, the raw materials comprise, by weight, 28 parts of the styrene, 72 parts of the butadiene, 3.5-5.0 parts of the emulsifier, 0.63-1.03 parts of the electrolyte, 0.02-0.10 part of the initiator, 0.06-0.08 part of the reducing agent, 0.12-0.22 part of the environment-friendly molecular weight regulator, 180-200 parts of the water and 0.35-0.50 part of the terminator.

5. The production method according to claim 4, wherein the emulsifier is a disproportionated potassium rosinate soap; preferably, the raw material comprises 4.0-4.5 parts of the emulsifier.

6. The method according to claim 4, wherein the electrolyte is selected from one or more of phosphoric acid, potassium hydroxide, ethylenediaminetetraacetic acid tetrasodium salt, and sodium dodecylbenzenesulfonate;

preferably, the electrolyte comprises 0.2-0.3 part by weight of the phosphoric acid, 0.3-0.5 part by weight of the potassium hydroxide, 0.03 part by weight of the ethylenediaminetetraacetic acid tetrasodium salt and 0.1-0.2 part by weight of the sodium dodecylbenzenesulfonate.

7. The method according to claim 4, wherein the initiator is p-menthane hydroperoxide.

8. The method according to claim 4, wherein the reducing agent is selected from an iron sodium salt and/or sodium formaldehyde sulfoxylate;

preferably, the reducing agent comprises 0.03 part of the iron sodium salt and 0.03-0.05 part of the sodium formaldehyde sulfoxylate.

9. A production method according to claim 4, wherein the terminator is selected from isopropylhydroxylamine and/or isopropylhydroxylamine hydrochloride.

10. The production method according to any one of claims 1 to 9, characterized by further comprising coagulating the styrene-butadiene latex under the action of a coagulant to obtain the styrene-butadiene rubber; preferably, in the condensation process, the condensation time is 5-20 min in a system with the temperature of 50-60 ℃ and the pH value of 3-4.

Technical Field

The invention relates to the field of rubber synthesis, and particularly relates to a preparation method of styrene butadiene rubber.

Background

The emulsion polymerized styrene butadiene rubber is a general synthetic rubber variety with highest global yield and largest consumption, and is mainly applied to the fields of automobile tires, industrial conveying belts, rubber tubes and the like. Styrene-butadiene rubber is a high molecular elastomer, and is usually prepared by emulsion polymerization of butadiene and styrene as raw materials. Styrene-butadiene rubber is a general synthetic rubber with the largest production quantity and use quantity in the world due to good physical and mechanical properties and processability, and is widely applied to the production of industrial and civil products, such as rubber products, tire treads, rubber shoes and other industrial products with higher requirements on physical properties.

The molecular weight regulator is also known as a chain transfer agent. In the course of free-radical polymerization, it is often necessary to add regulators in order to control the molecular weight of the polymer. Molecular weight regulators are very active substances in polymerization systems. It reacts readily with the growing macromolecular free radical, terminating the living chain, and the regulator molecule itself generates a new free radical having the same or similar activity as the macromolecular free radical, thus allowing continued initiation of polymerization. The molecular weight regulator can reduce the molecular weight of the polymer and has no great influence on the polymerization reaction rate. In addition, for the free radical polymerization reaction process of the alkadiene, the molecular weight regulator is added, so that the molecular weight can be controlled, and the 1,2 structure or 1,3 structure on the molecular chain of the polymer can be reduced, thereby reducing the hidden troubles of branching, crosslinking and gel generation of the alkadiene.

Most emulsion polymerization reactions are of the free radical type. Since the macromolecular free radicals are enclosed in the emulsion particles isolated from each other, only the initial free radicals (or active chains with extremely low molecular weight) extending from the aqueous phase into the emulsion particles can have termination reaction with the original free radical chains in the emulsion particles, while the free radicals in different emulsion particles have no chance to collide with each other to have chain termination reaction. Thus, compared to other free radical polymerization processes, emulsion polymerization has a low chain termination rate, long life of the macromolecular free radicals, and sufficient time for chain extension, and therefore the molecular weight of the polymers produced by the emulsion process is much greater than that of other polymerization processes. Meanwhile, since the polymerization reaction in the emulsion particles is mostly random polymerization, the polymer obtained by the emulsion method tends to have more 1,2 structures or 1,3 structures. Therefore, the addition of molecular weight regulator to control the molecular weight and molecular structure of polymer is more important for emulsion polymerization process, especially for the production of emulsion polymerized styrene-butadiene rubber.

Many compounds containing sulfur, nitrogen, phosphorus, selenium and having unsaturated bonds are useful as molecular weight regulators in emulsion polymerization systems. For emulsion polymerization of many monomers, the most used regulators are mercaptans, including normal mercaptans and branched mercaptans, and primary, secondary and tertiary mercaptans are all useful. It has been found that the number of carbon atoms in the thiol molecule used as molecular weight regulator is generally between 5 and 14. In organic chemistry, thiols are a class of non-aromatic compounds that contain a mercapto functional group (-SH). It can be seen as an organic compound in which oxygen in the alcohol is replaced by sulfur, and a mercapto group or mercapto-SH is bonded to an aliphatic hydrocarbon group. The compound formed by linking a mercapto group with a phenol-containing organic substance is called thiophenol, and is present in crude petroleum, and is usually various mercaptans mainly comprising ethanethiol. In addition, allyl thiol is present in mustard oil, and amino acids containing a thiol group, cysteine, are present in proteins. The properties of mercaptan and thiophenol are similar to those of alcohol and phenol. The mercaptan and the thiophenol have strong odor, and the odor can be smelled when the concentration of the ethanethiol in the air reaches 500 parts per billion.

The molecular weight regulator used in the current emulsion polymerized styrene butadiene rubber production technology is tert-dodecyl mercaptan. Mercaptan in the production field of a styrene butadiene rubber workshop has strong smell and is unpleasant, and the mercaptan has toxicity and the working environment of operators is severe. The novel molecular weight regulator is adopted to replace mercaptan, so that the odor of the mercaptan can be avoided, and the method has important significance for realizing green, environment-friendly and clean production. The preparation of synthetic resins using 2-mercaptoacetate and 2-mercaptopropionate compounds instead of thiols has been reported in succession at home and abroad.

The prior art provides an aqueous polymer dispersion prepared from a vinyl aromatic compound, a conjugated aliphatic diene and an ethylenically unsaturated acid, a process for its preparation by free-radical initiated emulsion polymerization. In a kind C₂-C₄Polymerizing a vinyl aromatic compound, a conjugated aliphatic diene, and an ethylenically unsaturated acid in an aqueous medium in the presence of a mercaptoalkylcarboxylic acid ester of a carboxylic acid and without using an alkylthiol as a molecular weight regulator. The polymer dispersion can be used as a binder, an adhesive and a fiber sizing agent for preparing paper coating pulp.

Another prior document provides a toner for electrostatic latent image development, the resin being obtained by emulsion polymerization, microemulsion polymerization using suspension polymerization of thioglycerol or at least one selected from the group consisting of₁-COOR₂(1) As a chain transfer agent. In the formula, R₁Is a carbon atom number ofMay be a compound containingAliphatic radical of carbon atoms, having substituents, R₂Is a carbon atom number ofThe aliphatic group of (3) may have a substituent.

Both the above-mentioned two preparation methods are aimed at the preparation of high-temperature emulsion resin, but the research on low-temperature emulsion polymerization reaction, in particular to low-temperature emulsion rubber of butadiene series, such as styrene-butadiene latex and butyronitrile latex, and low-odor environment-friendly molecular weight regulator has not been reported yet.

Disclosure of Invention

The invention mainly aims to provide a preparation method of styrene butadiene rubber, which aims to solve the problems of obvious peculiar smell and environmental pollution in the existing styrene butadiene rubber synthesis process.

In order to achieve the above objects, according to the present invention, there is provided a method for preparing styrene-butadiene rubber, comprising preparing styrene-butadiene latex by emulsion polymerization under the action of an environment-friendly molecular weight regulator, wherein the environment-friendly molecular weight regulator is 2-mercaptoisobutyric acid thiol ester and/or 2-mercaptobutyric acid thiol ester.

Further, the environment-friendly molecular weight regulator comprises one or more of the group consisting of isoheptyl 2-mercaptoisobutyrate, octyl 2-mercaptoisobutyrate, isoheptyl 2-mercaptobutyrate and octyl 2-mercaptobutyrate; preferably, the environment-friendly molecular weight regulator comprises 0.06-0.11 parts by weight of 2-mercaptoisobutyric acid isoheptyl mercaptan ester and 0.06-0.11 parts by weight of 2-mercaptoisobutyric acid octyl mercaptan ester.

Further, the weight ratio of 2-mercaptoisobutyric acid isoheptyl mercaptan ester to 2-mercaptoisobutyric acid octyl mercaptan ester is 1: 1-1.5.

Further, the preparation process of the styrene-butadiene latex comprises the following steps: under the action of nitrogen, taking styrene, butadiene, water, an emulsifier, an electrolyte, a reducing agent, an environment-friendly molecular weight regulator and an initiator as raw materials to carry out emulsion polymerization reaction, and adding a terminator into a reaction system of the emulsion polymerization reaction when the conversion rate of the raw materials reaches 60% to obtain styrene-butadiene latex, wherein the temperature of the emulsion polymerization reaction is less than or equal to 5 ℃; preferably, the raw materials comprise, by weight, 28 parts of styrene, 72 parts of butadiene, 3.5-5.0 parts of an emulsifier, 0.63-1.03 parts of an electrolyte, 0.02-0.10 part of an initiator, 0.06-0.08 part of a reducing agent, 0.12-0.22 part of an environment-friendly molecular weight regulator, 180-200 parts of water and 0.35-0.50 part of a terminator.

Further, the emulsifier is disproportionated potassium rosinate soap; preferably, the raw material comprises 4.0-4.5 parts of emulsifier.

Further, the electrolyte is selected from one or more of phosphoric acid, potassium hydroxide, ethylene diamine tetraacetic acid tetrasodium salt and sodium dodecyl benzene sulfonate; preferably, the electrolyte comprises 0.2-0.3 part of phosphoric acid, 0.3-0.5 part of potassium hydroxide, 0.03 part of ethylene diamine tetraacetic acid tetrasodium salt and 0.1-0.2 part of sodium dodecyl benzene sulfonate in parts by weight.

Further, the initiator is p-menthane hydroperoxide.

Further, the reducing agent is selected from iron sodium salt and/or sodium formaldehyde sulfoxylate; preferably, the reducing agent comprises 0.03 part of iron sodium salt and 0.03-0.05 part of sodium formaldehyde sulfoxylate.

Further, the terminating agent is selected from isopropyl hydroxylamine and/or isopropyl hydroxylamine hydrochloride.

Further, the preparation method also comprises the step of coagulating the styrene-butadiene latex under the action of a coagulant to obtain styrene-butadiene rubber; preferably, the coagulation process is carried out at a temperature of 50-60 ℃ and a pH value of 3-4 for a coagulation time of 5-20 min.

Compared with the prior C, the technical scheme of the invention₂～C₄The mercaptoalkyl carboxylate compounds of carboxylic acid, 2-mercaptoisobutyrate mercaptan ester compounds and 2-mercaptobutyrate mercaptan ester compounds have lower toxicity, and the compounds contain two sulfydryl groups and have stronger regulation capability on molecular weight. When the environment-friendly molecular weight regulator is used for preparing the styrene butadiene rubber, no obvious peculiar smell exists in the polymerization stage, the degassing stage and the condensation, washing and drying stage, the environment-friendly production is realized, the physical damage to operators is reduced, and simultaneously the styrene butadiene rubber product with moderate Mooney viscosity can be obtained.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

As described in the background art, the existing styrene butadiene rubber has the problems of obvious peculiar smell and environmental pollution in the synthesis process. In order to solve the technical problems, the application provides a preparation method of styrene-butadiene rubber, which comprises the step of preparing styrene-butadiene latex by adopting an emulsion polymerization method under the action of an environment-friendly molecular weight regulator, wherein the environment-friendly molecular weight regulator is 2-mercaptoisobutyric acid thiol ester and/or 2-mercaptobutyric acid thiol ester.

Compared with the prior C₂～C₄The mercaptoalkyl carboxylate compounds of carboxylic acid, 2-mercaptoisobutyrate mercaptan ester compounds and 2-mercaptobutyrate mercaptan ester compounds have lower toxicity, and the compounds contain two sulfydryl groups and have stronger regulation capability on molecular weight. When the environment-friendly molecular weight regulator is used for preparing the styrene butadiene rubber, no obvious peculiar smell exists in the polymerization stage, the degassing stage and the condensation, washing and drying stage, the environment-friendly production is realized, the body damage to operators is reduced, and simultaneously the styrene butadiene rubber product with moderate Mooney viscosity can be obtained.

In a preferred embodiment, the above-mentioned eco-friendly molecular weight regulator comprises one or more selected from the group consisting of isoheptylmercaptyl 2-mercaptoisobutyrate, octylmercaptyl 2-mercaptoisobutyrate, isoheptylmercaptyl 2-mercaptobutyrate and octylmercaptyl 2-mercaptobutyrate. The above-mentioned environment-friendly molecular weight regulators include, but are not limited to, the above-mentioned substances, which are selected as molecular weight regulators in emulsion polymerization, are favorable for further reducing the odor in the whole emulsion polymerization.

In order to further improve the regulation capability of the environment-friendly molecular weight to the molecular weight, in a preferred embodiment, the environment-friendly molecular weight regulator comprises 0.06-0.11 part by weight of 2-mercaptoisobutyric acid isoheptyl mercaptan ester and 0.06-0.11 part by weight of 2-mercaptoisobutyric acid octyl mercaptan ester. More preferably, the weight ratio of 2-mercaptoisobutyric acid isoheptyl mercaptan ester to 2-mercaptoisobutyric acid octyl mercaptan ester in the environment-friendly molecular weight regulator is 1: 1-1.5.

In order to further improve the regulation capability of the environment-friendly molecular weight to the molecular weight, in another preferred embodiment, the environment-friendly molecular weight regulator comprises 0.06-0.11 part of 2-mercaptobutyric acid isoheptyl mercaptan and 0.06-0.11 part of 2-mercaptobutyric acid octyl mercaptan by weight. More preferably, the weight ratio of 2-mercaptobutyric acid isoheptyl mercaptan and 2-mercaptobutyric acid octyl mercaptan in the environment-friendly molecular weight regulator is 1: 1-1.5.

The adoption of the environment-friendly molecular weight regulator is beneficial to greatly reducing the peculiar smell generated in the synthetic process of the styrene butadiene rubber. In a preferred embodiment, the styrene-butadiene latex is prepared by a process comprising: under the action of nitrogen, styrene, butadiene, water, an emulsifier, an electrolyte, a reducing agent, an environment-friendly molecular weight regulator and an initiator are used as raw materials for emulsion polymerization reaction, when the conversion rate of the raw materials reaches 60%, a terminator is added into a reaction system of the emulsion polymerization reaction to obtain styrene-butadiene latex, and the temperature of the emulsion polymerization reaction is less than or equal to 5 ℃. Preferably, the raw materials comprise, by weight, 28 parts of styrene, 72 parts of butadiene, 3.5-5.0 parts of an emulsifier, 0.63-1.03 parts of an electrolyte, 0.02-0.10 part of an initiator, 0.06-0.08 part of a reducing agent, 0.12-0.22 part of an environment-friendly molecular weight regulator, 180-200 parts of water and 0.35-0.50 part of a terminator.

In the emulsion polymerization process, the amount of the raw materials used includes, but is not limited to, the above ratio range, and the limitation of the amount to the above range is beneficial to further improving the comprehensive performance of the styrene butadiene rubber and the environmental protection of the reaction process.

In the above emulsion polymerization, the emulsifier may be any emulsifier commonly used in the art. In a preferred embodiment, the emulsifier includes, but is not limited to, disproportionated potassium rosinate soap. The adoption of the emulsifiers is beneficial to further improving the emulsification effect of each component, improving the reaction uniformity and further being beneficial to improving the performance of the styrene butadiene rubber. More preferably, the raw material comprises 4.0-4.5 parts of emulsifier.

In the above emulsion polymerization, the electrolyte may be any of those commonly used in the art. In a preferred embodiment, the electrolyte includes, but is not limited to, one or more of phosphoric acid, potassium hydroxide, ethylenediaminetetraacetic acid, tetrasodium salt, and sodium dodecylbenzenesulfonate. The electrolyte used herein has good diffusibility and low foaming ability compared to other electrolytes. Preferably, the electrolyte comprises 0.2-0.3 part of phosphoric acid, 0.3-0.5 part of potassium hydroxide, 0.03 part of ethylene diamine tetraacetic acid tetrasodium salt and 0.1-0.2 part of sodium dodecyl benzene sulfonate in parts by weight. The amount of each component in the electrolyte includes, but is not limited to, the above range, and the limitation of the amount to the above range is beneficial to further improving the emulsification effect of the emulsion polymerization reaction, and further beneficial to improving the comprehensive performance of the styrene butadiene rubber.

In the above preparation method provided herein, an initiator commonly used in the art can be used, and preferably, the initiator includes, but is not limited to, p-menthane hydroperoxide.

In a preferred embodiment, the reducing agent includes, but is not limited to, iron sodium salt and/or sodium formaldehyde sulfoxylate. The reducing agent used in the method can effectively remove oxygen in a system, so that the polymerization activity is improved, the polymerization rate tends to be reasonable and stable, and the polymerization conversion rate and the stability of the mooney of the cement are ensured. More preferably, the reducing agent comprises 0.03 part of iron sodium salt and 0.03-0.05 part of sodium formaldehyde sulfoxylate.

In a preferred embodiment, the terminating agent includes, but is not limited to, isopropylhydroxylamine and/or isopropylhydroxylamine hydrochloride. The types of the terminating agents include, but are not limited to, the above substances are selected as the terminating agents, which is beneficial to further accelerate the terminating process of the emulsion polymerization reaction and reduce the generation of byproducts.

In a preferred embodiment, the preparation method further comprises coagulating the styrene-butadiene latex under the action of a coagulant to obtain styrene-butadiene rubber; preferably, the coagulation process is carried out at a temperature of 50-60 ℃ and a pH value of 3-4 for a coagulation time of 5-20 min. Compared with other reaction temperature, reaction time and pH, the emulsion polymerization reaction carried out at the reaction temperature, the reaction time and the pH can obviously improve the branching and crosslinking condition of the emulsion polymerized styrene butadiene rubber, thereby improving the comprehensive performance of the emulsion polymerized styrene butadiene rubber.

The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.