阅读说明：本技术 一种低分子量聚合物的制备方法 (Preparation method of low molecular weight polymer ) 是由 华静 汤健 谢廷皓 刘金慧 耿洁婷 于 2020-08-15 设计创作，主要内容包括：本发明涉及一种低分子量聚合物的制备方法。在含不饱和双键的聚烯烃溶液中加入催化剂和添加剂进行降解反应,降解完成后,加入活泼质子物质终止反应,洗涤干燥,得低分子量聚合物；其中,所述的含不饱和双键的聚烯烃为聚共轭二烯烃或含不饱和双键的丁苯、丁腈和丁戊共聚物；所述的催化剂为烷基金属化合物、碱金属及其化合物或它们的混合物；所述的添加剂为四氢呋喃、二氧六环、金属醇盐或四甲基乙二胺中的一种。本发明采用含不饱和双键的聚烯烃裂解制备低分子量的聚合物,产物的数均分子量可从数十万降低至数千。反应条件温和,时间短,催化剂成本低,适用的聚合物种类多。(The invention relates to a preparation method of a low molecular weight polymer. Adding a catalyst and an additive into a polyolefin solution containing unsaturated double bonds for degradation reaction, adding an active proton substance to terminate the reaction after the degradation is finished, washing and drying to obtain a low molecular weight polymer; wherein, the polyolefin containing unsaturated double bonds is poly conjugated diene or a butylbenzene, butyronitrile and butadiene-isoprene copolymer containing unsaturated double bonds; the catalyst is alkyl metal compound, alkali metal and compound thereof or mixture thereof; the additive is one of tetrahydrofuran, dioxane, metal alkoxide or tetramethyl ethylene diamine. The invention adopts polyolefin containing unsaturated double bonds to prepare low molecular weight polymer by cracking, and the number average molecular weight of the product can be reduced from hundreds of thousands to thousands. The reaction condition is mild, the time is short, the catalyst cost is low, and the types of applicable polymers are various.)

1. A method for preparing a low molecular weight polymer, comprising: adding a catalyst and an additive into a polyolefin solution containing unsaturated double bonds for degradation reaction, adding an active proton substance to terminate the reaction after the degradation is finished, washing and drying to obtain a low molecular weight polymer; wherein the content of the first and second substances,

the polyolefin containing unsaturated double bonds is poly conjugated diene or a copolymer of butylbenzene, butyronitrile and butadiene-pentane containing unsaturated double bonds;

the catalyst is alkyl metal compound, alkali metal and compound thereof or mixture thereof;

the additive is one of tetrahydrofuran, dioxane, metal alkoxide or tetramethyl ethylene diamine.

2. The method for producing a low-molecular weight polymer according to claim 1, characterized in that: the polyolefin containing unsaturated double bonds is natural rubber, high vinyl polybutadiene rubber, polyisoprene rubber or butadiene rubber.

3. The method for producing a low-molecular weight polymer according to claim 1, characterized in that: the solvent adopted by the polyolefin solution containing unsaturated double bonds is saturated hydrocarbon, aromatic hydrocarbon or a mixture thereof.

4. The method for producing a low-molecular weight polymer according to claim 1, characterized in that: the concentration of the polyolefin solution containing unsaturated double bonds is 0.01-2 g/mL.

5. The method for producing a low-molecular weight polymer according to claim 1, characterized in that: the alkyl metal compound is alkyl lithium, alkyl sodium or alkyl potassium, and the alkali metal and the compound thereof are simple substance lithium, simple substance sodium, simple substance potassium, sodium amide, potassium amide or sodium naphthalene complex.

6. The method for producing a low-molecular weight polymer according to claim 1, characterized in that: the addition amount of the catalyst is 1-300% of the double bond amount of the polyolefin containing unsaturated double bonds.

7. The method for producing a low-molecular weight polymer according to claim 1, characterized in that: the addition amount of the additive is 1-300% of the double bond amount of the polyolefin containing unsaturated double bonds.

8. The method for producing a low-molecular weight polymer according to claim 1, characterized in that: the degradation reaction is carried out at the temperature of room temperature to 80 ℃ for 10min-2 h.

9. The method for producing a low-molecular weight polymer according to claim 1, characterized in that: the active proton substance is water or alcohol.

10. The method for producing a low-molecular weight polymer according to claim 1, characterized in that: the number average molecular weight of the low molecular weight polymer is 100-30000.

Technical Field

The invention belongs to the technical field of preparation and processing modification of rubber materials, and particularly relates to a preparation method of a low molecular weight polymer.

Background

Low molecular weight polymers have a wide range of applications, with the most common low molecular weight polymers being liquid polybutadiene, liquid polyisoprene, and the like. These low molecular weight polymers are commonly used as thermosetting resins, adhesives, rubber and plastic processing aids, and the like.

The low molecular weight polymer in China has low yield, incomplete varieties and lack of market competitiveness, and high-end products are monopolized abroad for a long time. The development of the preparation technology of the low molecular weight liquid polymer is in line with the development direction of the national rubber industry.

Patent CN 1241989C discloses a method for preparing low molecular polybutadiene, which is prepared by polymerizing butadiene monomer with butyl lithium in the presence of potassium salt, and the NISSO-PB product produced by japan caoka co. The method is a monomer polymerization mode, and the low molecular weight polymer is obtained by controlling the dosage of the initiator, so that the method does not relate to more extensive polymer production.

Patent CN 1831021a describes a process for preparing low branch content polybutadiene, which requires three stages of polymerization, coupling and recovery to prepare low branch content polybutadiene. The patent CN101492514A discloses a high cis-1, 4 structure content (> 95%), a low molecular weight-average molecular weight (Mw is 5,600-120,000) and a narrow molecular weight distribution (Mw/Mn is 1.1-2.0), wherein the polyisoprene adopts a coordination polymerization mechanism. The method mainly applies a monomer polymerization mode to obtain a low molecular polymer, the reaction is carried out in multiple steps, wherein after a transition metal catalyst is added in the first step, alkyl aluminum is also added as a cocatalyst, and then a coupling agent is added to treat the product.

High cis-1, 4 content hydroxyl-terminated polybutadiene liquid rubber and a preparation method thereof (CN104211838A) are developed by interleukin cloud and the like at Zhejiang university, a low molecular weight polymer is prepared from macromolecular polybutadiene by adopting an epoxidation-bond breaking mode, the number average molecular weight of the product is 2000-10000, and the molecular weight is distributed between 1.2 and 3.0. Aiming at polybutadiene series products, the method selects the reaction time of 1-12h in order to achieve high-efficiency catalytic activity, and a reaction system selects a transition metal catalyst, dichloromethane and other complex compounds.

At present, an oligomer production mode with milder reaction conditions, lower catalyst cost and shorter production process conditions is lacked. In addition, the existing oligomer preparation methods are mostly limited to the production of one or a few oligomers, and methods which can be applied to the production of a plurality of oligomers will be widely welcomed.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a preparation method of a low molecular weight polymer, which prepares the low molecular weight polymer by cracking polyolefin containing unsaturated double bonds, and has the advantages of mild reaction conditions, short time, low catalyst cost and various applicable polymers.

Adding a catalyst and an additive into a polyolefin solution containing unsaturated double bonds for degradation reaction, adding an active proton substance to terminate the reaction after the degradation is finished, washing and drying to obtain a low molecular weight polymer; wherein the content of the first and second substances,

the polyolefin containing unsaturated double bonds is poly conjugated diene or a copolymer of butylbenzene, butyronitrile and butadiene-pentane containing unsaturated double bonds;

the catalyst is alkyl metal compound, alkali metal and compound thereof or mixture thereof, and the preferable catalyst is alkyl metal compound;

the additive is one of tetrahydrofuran, dioxane, metal alkoxide or tetramethyl ethylene diamine, and the preferable additive is tetramethyl ethylene diamine;

wherein:

the polyolefin containing unsaturated double bonds is natural rubber, high vinyl polybutadiene rubber, polyisoprene rubber or butadiene rubber.

The solvent adopted by the polyolefin solution containing unsaturated double bonds is saturated hydrocarbon, aromatic hydrocarbon or a mixture thereof. Preferred solvents are n-hexane or toluene.

The concentration of the polyolefin solution containing unsaturated double bonds is 0.01-2 g/mL.

The alkyl metal compound is alkyl lithium, alkyl sodium or alkyl potassium. N-butyllithium, sec-butyllithium, and tert-butyllithium are preferred.

The alkali metal and the compound thereof are simple substance lithium, simple substance sodium, simple substance potassium, sodium amide, potassium amide or sodium naphthalene complex.

The addition amount of the catalyst is 1-300% of the double bond amount of the polyolefin containing unsaturated double bonds.

The addition amount of the additive is 1-300% of the double bond amount of the polyolefin containing unsaturated double bonds.

The degradation reaction is carried out at the temperature of room temperature to 80 ℃ for 10min-2 h.

The active proton substance is water or alcohol.

The number average molecular weight of the low molecular weight polymer is 100-30000. Typically one-thousand to one-half of the molecular weight of the original polymer.

The reaction mechanism of the invention, taking hexa-polyisoprene as an example, is as follows:

compared with the prior art, the invention has the following beneficial effects:

the invention adopts polyolefin containing unsaturated double bonds to prepare low molecular weight polymer by cracking, and the number average molecular weight of the product can be reduced from hundreds of thousands to thousands. The reaction condition is mild, the time is short, the catalyst cost is low, and the types of applicable polymers are various.

Detailed Description

The present invention will be further described with reference to the following embodiments.