Silicone rubber based on mechanochemical method and preparation method thereof

Abstract

A kind of silicone rubber and preparation method based on mechanochemical method, belonging to the field of polymer materials. It is a process method that uses silicone oil containing epoxy groups and small molecular compounds or mixtures containing polyhydroxyl or carboxyl groups to undergo mechanochemical reaction under the catalysis of amine compounds to generate a kind of polymer silicone rubber. This method has a wide range of raw materials, mild reaction conditions, no need to use solvents, simple reaction process and post-treatment, and solves the problems of complex silicone rubber synthesis process and harsh conditions. The overall reaction conversion rate exceeds 90%, which is a high-efficiency, low-cost green synthesis technology.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and relates to a silicone rubber based on a mechanochemical method and a preparation method thereof, which is a method for preparing a class of silicone rubber polymers based on a mechanochemical reaction of silicone oils containing multiple epoxy groups with compounds or mixtures containing multiple hydroxyl groups and carboxyl groups under the action of amine catalysts. Background Art

[0002] Silicone materials are a type of polysiloxane with Si-O as repeating units forming the main chain and organic groups connected to silicon atoms. They mainly include three types of products: silicone oil, silicone rubber and silicone resin. Compared with other polymer materials, they have excellent flexibility, biocompatibility, high and low temperature resistance, and aging resistance. They can be widely used in various fields such as aerospace, biomedicine and industrial production.

[0003] Silicone rubber is the most widely used among organic silicon materials. Its main chain structure is polydimethylsiloxane. The introduction of heteroatoms or special functional groups in the main chain or side groups can give silicone rubber special properties. For example, the introduction of phenyl groups in silicone rubber can increase the material's high temperature resistance, the introduction of ethyl groups can increase the material's low temperature resistance, and the introduction of cyano groups can improve the material's oil resistance.

[0004] There are two main methods for traditional silicone rubber synthesis, which can be divided into condensation polymerization and ring-opening polymerization according to the reaction type. In the former, the siloxane monomer is first hydrolyzed to obtain a silanol structure in the synthesis system, and then the small molecule water is removed to generate a macromolecular polysiloxane. The reaction process requires precise control of temperature, time and other conditions; the latter is divided into anionic ring-opening polymerization and cationic ring-opening polymerization according to the different catalysts. Under the action of acidic or alkaline catalysts (such as tetramethylammonium hydroxide, trifluoromethylsulfonic acid, etc.), elementary reactions such as chain initiation, chain growth and chain termination occur to obtain macromolecular polysiloxane.

[0005] Groups that can undergo selective chemical responses under mechanical forces are called force-sensitive groups. The method of introducing force-sensitive groups into molecules so that the molecular chains can change their structures and undergo chemical reactions under the action of mechanical forces is called mechanochemical method. Mechanochemical reactions are mainly achieved through grinding, shearing, impact, pressure, etc. Therefore, the need for high temperatures or large amounts of solvents can be avoided during the reaction process, and the post-processing of the obtained products is often more convenient. It is a simple, safe, and efficient green synthesis technology.

[0006] At present, mechanochemical methods have been gradually applied to the preparation of metal-based composite materials and the degradation of organic compounds. Epoxy groups have unique application prospects in the synthesis of mechanochemical methods due to their special reactivity, adsorption and cross-linking properties. For example, the inventor's previous patent document CN112409583A discloses a method for preparing animal / plant oil bio-based polymers based on a mechanochemical method, using epoxy animal / plant oils and small molecular compounds or mixtures containing polyhydroxyl groups, carboxyl groups, etc. to carry out mechanochemical reactions, thereby preparing a class of bio-based, degradable polymers.

[0007] The present invention proposes a process for producing organic silicone rubber by mechanochemically reacting silicone oil containing epoxy groups with multifunctional small molecule compounds. The main feature of the method is that silicone oil containing epoxy groups is used as raw material to synthesize high molecular weight elastomer by mechanochemical method. The method has a wide range of raw material sources, a simple synthesis method, no solvent is required, and post-processing is simple, which greatly improves the production efficiency and reduces the cost. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides a process for generating a type of high molecular weight organic silicone rubber by a mechanochemical reaction between silicone oil containing epoxy groups and a small molecule compound or mixture containing polyhydroxyl or carboxyl groups under the catalytic action of amine compounds.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A method for preparing silicone rubber based on a mechanochemical method, wherein the method does not require the use of solvents and does not require post-processing. The specific steps are:

[0011] First, at room temperature, epoxy silicone oil (i.e. silicone oil containing epoxy groups), small molecule substances and epoxy catalysts are sequentially added into a reactor and mixed evenly to obtain a mixture, wherein the mass ratio of epoxy silicone oil, small molecule substances and catalyst is 400-30:10-2:1.

[0012] Secondly, the mixture is quickly placed in a mechanochemical device, mechanical force is applied to the mixture, and a mechanochemical reaction is carried out for 2-8 hours; at this time, the epoxy groups in the epoxy silicone oil are ring-opened under the action of an amine catalyst, and under the action of mechanical force, addition polymerization occurs with the polyol / phenol / acid groups in the small molecule compound to obtain a polymer rich in siloxy groups.

[0013] Finally, after the reaction is completed, the product is removed from the mechanochemical equipment and left to stand for more than 24 hours. Through deep reaction, the reaction product is further cross-linked to obtain a network structure. The product changes from a viscous liquid to an elastic solid, and finally a high molecular weight silicone rubber is prepared.

[0014] Furthermore, the epoxy silicone oil includes but is not limited to dual-end epoxy silicone oil, side-chain epoxy silicone oil or a mixture of the two.

[0015] Furthermore, the molecular weight of the epoxy silicone oil is 4000-30000, the polydispersity of the epoxy silicone oil is 1-4, and the epoxy value of the epoxy silicone oil is 0.1-0.9.

[0016] Furthermore, the small molecule reactants include polyphenols, acids, and alcohols; wherein the polyphenols include catechol, resorcinol, hydroquinone, and lignin, the alcohols include glycerol and glucose, and the acids include maleic acid and succinic acid.

[0017] Furthermore, the epoxy catalyst includes urea, ethylenediamine, triethylamine, m-phenylenediamine, and p-phenylenediamine.

[0018] Furthermore, the mechanochemical equipment includes: a high-speed mixer, a ball mill, and an ultrasonic device; the mechanical forces used in the mechanochemical reaction in the synthesis process include: stirring, ball milling, ultrasound, and shearing.

[0019] A silicone rubber based on a mechanochemical method is prepared by the above method. The silicone rubber is an elastic solid with a number average molecular weight of 30,000 to 100,000 and a molecular weight distribution of 1.5 to 3.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: silicone rubber can be prepared directly from functionalized silicone oil as raw material, the reaction conditions are mild, the process is simple, no solvent is required, and the conversion rate exceeds 90%. Compared with the existing method for synthesizing silicone rubber, the present invention greatly improves the production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a comparison chart of the molecular weight test of silicone rubber prepared by the mechanochemical method in Example 1.

[0022] Figure 2 This is the DSC test curve of the silicone rubber prepared by the mechanochemical method in Example 2.

[0023] Figure 3 This is the DSC test curve of the silicone rubber prepared by the mechanochemical method in Example 3.

[0024] Figure 4 This is the DSC test curve of the silicone rubber prepared by the mechanochemical method in Example 4.

[0025] Figure 5 This is the DCS test curve of silicone rubber prepared by the mechanochemical method in Example 5. DETAILED DESCRIPTION

[0026] The present invention provides the following examples as further illustrations, but they are not intended to limit the scope of protection of the claims of the present invention.

[0027] Example 1

[0028] Weigh the double-terminal epoxy silicone oil and catechol according to the mass ratio of the two reactants, mix the two reactants and add them into a high-speed stirring device, then add the catalyst ethylenediamine for high-speed stirring, and after the reaction is completed, place the product in a reactor and let it stand for 24 hours. The specific steps are:

[0029] In the first step, 500 g of double-ended epoxy silicone oil (molecular weight 4000, polydispersity 1.2) and 16.5 g of catechol (mass ratio of the two reactants 30:1) were added to the reactor in sequence at room temperature, and then 5 ml of ethylenediamine catalyst was added after mixing evenly. The reactants were quickly placed in a stirrer and rapidly stirred for 2 hours at a stirring speed of 250 tr / min.

[0030] In the second step, after the reaction is completed, the product is taken out from the agitator and allowed to stand in the reactor for 24 hours.

[0031] The third step is to immerse the product in anhydrous ethanol to wash away the unreacted epoxy oil, small molecules and catalyst to obtain a high molecular weight silicone rubber. The high molecular weight silicone rubber obtained in this embodiment has a number average molecular weight of about 30,000 and a molecular weight distribution of 1.7.

[0032] Example 2

[0033] Weigh the side chain epoxy silicone oil and resorcinol according to the mass ratio of the two reactants, add the catalyst urea, put the mixture of the three into an ultrasonic instrument for ultrasonication, and after the reaction is completed, place the product in a reactor and let it stand for 72 hours. The specific steps are:

[0034] In the first step, 500 g of side chain epoxy silicone oil (molecular weight 6000, polydispersity 1.4), 10 g of resorcinol (mass ratio of the two reactants 50:1) and 4 g of urea catalyst were added to the reactor in sequence at room temperature. After mixing evenly, the reactants were quickly placed in an ultrasonic instrument for ultrasonic reaction for 3 hours, wherein the ultrasonic frequency of the ultrasonic instrument was 40 kHz.

[0035] In the second step, after the reaction is completed, the product is taken out from the ultrasonic instrument and allowed to stand in the reactor for 72 hours.

[0036] In the third step, the product is immersed in anhydrous ethanol to wash away unreacted epoxy oil, small molecules and catalyst to obtain polymer silicone rubber. The polymer silicone rubber obtained in this embodiment has a number average molecular weight of about 35,000, a molecular weight distribution of 1.55, and a glass transition temperature of -122.64°C.

[0037] Example 3

[0038] Weigh the mixture of double-end epoxy silicone oil and side-chain epoxy silicone oil and lignin according to the mass ratio of the two reactants, then add the catalyst triethylamine, put the mixture of the three into a ball mill for ball milling, and after the reaction is completed, place the product in a reactor and let it stand for 48 hours. The specific steps are:

[0039] In the first step, 500 g of a mixture of double-ended epoxy silicone oil and side-chain epoxy silicone oil (molecular weight 10,000, polydispersity 2), 5 g of lignin (mass ratio of the two reactants 100:1) and 3 ml of triethylamine catalyst were added to the reactor at room temperature in sequence. After mixing evenly, the reactants were quickly placed in a ball mill for ball milling for 4 hours, with a ball milling speed of 200 rpm.

[0040] In the second step, after the reaction is completed, the product is taken out from the ball mill and allowed to stand in the reactor for 48 hours.

[0041] In the third step, the product is immersed in anhydrous ethanol to wash away unreacted epoxy oil, small molecules and catalyst to obtain polymer silicone rubber. The polymer silicone rubber obtained in this embodiment has a number average molecular weight of about 45,000, a molecular weight distribution of 2.3, and a crystallization temperature of -81.76°C.

[0042] Example 4

[0043] Weigh the double-terminal epoxy silicone oil and glycerol according to the mass ratio of the two reactants, then add the catalyst m-phenylenediamine, mix the three and add them into a high-speed stirring device for high-speed stirring. After the reaction is completed, place the product in a reactor and let it stand for 24 hours. The specific steps are:

[0044] In the first step, 500 g of double-ended epoxy silicone oil (molecular weight 15,000, polydispersity 2.6), 2 g of glycerol (mass ratio of the two reactants 250:1) and 3 g of meta-phenylenediamine catalyst were added to the reactor in sequence at room temperature. After mixing evenly, the reactants were quickly placed in a stirrer for rapid stirring for 4 hours at a stirring speed of 300 tr / min.

[0045] In the second step, after the reaction is completed, the product is taken out from the agitator and allowed to stand in the reactor for 24 hours.

[0046] In the third step, the product is immersed in anhydrous ethanol to wash away unreacted epoxy oil, small molecules and catalyst to obtain polymer silicone rubber. The polymer silicone rubber obtained in this embodiment has a number average molecular weight of about 62,000, a molecular weight distribution of 2.2, and a crystallization temperature of -87.36°C.

[0047] Example 5

[0048] Weigh the side chain epoxy silicone oil and maleic acid according to the mass ratio of the two reactants, then add the catalyst ethylenediamine, put the mixture of the three into an ultrasonic instrument for ultrasonication, and after the reaction is completed, place the product in a reactor and let it stand for 72 hours. The specific steps are:

[0049] In the first step, 500 g of side chain epoxy silicone oil (molecular weight 15,000, polydispersity 2.1), 5 g of maleic acid (mass ratio of the two reactants 100:1) and 3 ml of ethylenediamine catalyst were added to the reactor in sequence at room temperature. After mixing evenly, the reactants were quickly placed in an ultrasonic instrument for ultrasonic reaction for 4 hours, wherein the ultrasonic frequency of the ultrasonic instrument was 40 kHz.

[0050] In the second step, after the reaction is completed, the product is taken out from the ultrasonic instrument and allowed to stand in the reactor for 72 hours.

[0051] In the third step, the product is immersed in anhydrous ethanol to wash away the unreacted epoxy oil, small molecules and catalyst to obtain a high molecular weight silicone rubber. The high molecular weight silicone rubber obtained in this embodiment has a number average molecular weight of about 63,000, a molecular weight distribution of 1.9, a glass transition temperature of -120.09°C, and a crystallization temperature of -89.76°C.

[0052] Example 6

[0053] Weigh the mixture of double-ended epoxy silicone oil and side-chain epoxy silicone oil and catechol according to the mass ratio of the two reactants, then add catalyst urea, put the mixture of the three into a ball mill for ball milling, and after the reaction is completed, place the product in a reactor and let it stand for 48 hours. The specific steps are:

[0054] In the first step, 500 g of a mixture of double-ended epoxy silicone oil and side-chain epoxy silicone oil (molecular weight 20,000, polydispersity 3.2), 2.75 g of catechol (mass ratio of the two reactants 180:1) and 2 g of urea catalyst were added to the reactor in sequence at room temperature. After mixing evenly, the reactants were quickly put into a ball mill for ball milling for 6 hours, with a ball milling speed of 300 rpm.

[0055] In the second step, after the reaction is completed, the product is taken out from the ball mill and allowed to stand in the reactor for 48 hours.

[0056] The third step is to immerse the product in anhydrous ethanol to wash away the unreacted epoxy oil, small molecules and catalyst to obtain a high molecular weight silicone rubber. The high molecular weight silicone rubber obtained in this embodiment has a number average molecular weight of about 86,000 and a molecular weight distribution of 2.8.

[0057] Example 7

[0058] Weigh the double-terminal epoxy silicone oil and hydroquinone according to the mass ratio of the two reactants, then add the catalyst triethylamine, mix the three and add them into a high-speed stirring device for high-speed stirring. After the reaction is completed, place the product in a reactor and let it stand for 24 hours. The specific steps are:

[0059] In the first step, 500 g of double-ended epoxy silicone oil (molecular weight 25,000, polydispersity 3), 2.5 g of hydroquinone (mass ratio of the two reactants 200:1) and 2 ml of triethylamine catalyst were added to the reactor in sequence at room temperature. After mixing evenly, the reactants were quickly placed in a stirrer for rapid stirring for 8 hours, with a stirring speed of 350 tr / min.

[0060] In the second step, after the reaction is completed, the product is taken out from the agitator and allowed to stand in the reactor for 24 hours.

[0061] In the third step, the product is immersed in anhydrous ethanol to wash away unreacted epoxy oil, small molecules and catalyst to obtain a high molecular weight silicone rubber. The high molecular weight silicone rubber obtained in this embodiment has a number average molecular weight of about 89,000 and a molecular weight distribution of 2.3.

[0062] Example 8

[0063] Weigh the double-terminal epoxy silicone oil and glycerol according to the mass ratio of the two reactants, then add the catalyst ethylenediamine, mix the three and add them into a high-speed stirring device for high-speed stirring. After the reaction is completed, place the product in a reactor and let it stand for 24 hours. The specific steps are:

[0064] In the first step, 500 g of double-ended epoxy silicone oil (molecular weight 30,000, polydispersity 4), 1.25 g of glycerol (mass ratio of the two reactants 400:1) and 1 ml of ethylenediamine catalyst were added to the reactor in sequence at room temperature. After mixing evenly, the reactants were quickly placed in a stirrer for rapid stirring for 8 hours, with a stirring speed of 350 tr / min.

[0065] In the second step, after the reaction is completed, the product is taken out from the agitator and allowed to stand in the reactor for 24 hours.

[0066] The third step is to immerse the product in anhydrous ethanol to wash away the unreacted epoxy oil, small molecules and catalyst to obtain a high molecular weight silicone rubber. The high molecular weight silicone rubber obtained in this embodiment has a number average molecular weight of about 100,000 and a molecular weight distribution of 2.8.

[0067] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing silicone rubber based on a mechanochemical method, characterized in that: The preparation method does not require the use of solvents and does not require post-treatment; the specific steps are: First, at room temperature, epoxy silicone oil, a small molecule reactant and an epoxy catalyst are sequentially added into a reactor, and the three are mixed evenly to obtain a mixture, wherein the mass ratio of the epoxy silicone oil, the small molecule reactant and the catalyst is 400-30:10-2:1; the epoxy catalyst is an amine catalyst; and the small molecule reactant includes polyphenols, acids or alcohols; Secondly, the mixture is quickly placed in a mechanochemical device, a mechanical force is applied to the mixture, and a mechanochemical reaction is carried out for 2-8 hours; At this time, the epoxy groups in the epoxy silicone oil undergo ring opening under the action of amine catalysts, and under the action of mechanical force, undergo addition polymerization with the polyol / phenol / acid groups in the small molecule reactants to obtain a polymer rich in siloxy groups; Finally, after the reaction is completed, the product is removed from the mechanochemical equipment and left to stand for more than 24 hours. Through deep reaction, the reaction product is further cross-linked to obtain a high-molecular silicone rubber with a network structure.

2. The method for preparing silicone rubber based on a mechanochemical method according to claim 1, characterized in that: The epoxy silicone oil includes double-end epoxy silicone oil, side-chain epoxy silicone oil or a mixture of the two.

3. The method for preparing silicone rubber based on a mechanochemical method according to claim 1, characterized in that: The molecular weight of the epoxy silicone oil is 4000-30000, the polydispersity of the epoxy silicone oil is 1-4, and the epoxy value of the epoxy silicone oil is 0.1-0.

9.

4. The method for preparing silicone rubber based on a mechanochemical method according to claim 1, characterized in that: The polyphenols include catechol, resorcinol, hydroquinone or lignin, the alcohols include glycerol or glucose, and the acids include maleic acid or succinic acid.

5. The method for preparing silicone rubber based on a mechanochemical method according to claim 1, characterized in that: The epoxy catalyst includes urea, ethylenediamine, triethylamine, m-phenylenediamine or p-phenylenediamine.

6. The method for preparing silicone rubber based on a mechanochemical method according to claim 1, characterized in that: The mechanochemical equipment includes: a high-speed mixer, a ball mill or an ultrasonic instrument; the mechanical forces used in the mechanochemical reaction in the synthesis process include: stirring, ball milling, ultrasound or shearing.

7. A silicone rubber based on a mechanochemical method, characterized in that: The silicone rubber is prepared by the preparation method described in any one of claims 1 to 6, wherein the silicone rubber is an elastic solid with a number average molecular weight of 30,000 to 100,000 and a molecular weight distribution of 1.5 to 3.

Images