Process for removing metal catalyst from the gum solution after hydrogenation of unsaturated polymers

Abstract

The present application relates to the field of unsaturated polymer hydrogenation, and discloses a method for removing metal catalyst in glue liquid after unsaturated polymer hydrogenation, which comprises the following steps: (1) mixing a complexing agent, an extractant and glue liquid after unsaturated polymer hydrogenation; (2) carrying out oil-water separation on the mixture obtained in step (1) under the action of a voltage of 200-2000 V / cm. The method of the present application can remove metal catalyst in glue liquid under a specific voltage, improve the removal rate of metal catalyst, improve the separation effect of oil phase and water phase, shorten the operation cycle and improve the separation efficiency. Meanwhile, the method of the present application can further reduce the amount of extractant.

Description

Technical Field

[0001] This invention relates to the field of hydrogenation of unsaturated polymers, and more specifically to a method for removing metal catalysts from the colloidal solution after hydrogenation of unsaturated polymers. Background Technology

[0002] Unsaturated copolymers such as nitrile butadiene rubber (NBR) are produced by low-temperature emulsion polymerization of butadiene and acrylonitrile. They exhibit excellent oil resistance, high abrasion resistance, good heat resistance, and strong adhesion. However, due to the presence of carbon-carbon double bonds in their molecular chain, they suffer from poor low-temperature resistance, poor ozone resistance, inferior insulation properties, and slightly lower elasticity. Catalytic hydrogenation of these carbon-carbon double bonds yields hydrogenated NBR, which not only retains the original properties of NBR but also improves its overall performance, including heat resistance, ozone resistance, and resistance to acidic fuels. Hydrogenated NBR is widely used in the automotive industry. In Japan, for example, 60% of its consumption is used to manufacture automotive timing belts, 20% is used to manufacture power steering seals, air regulator seals, O-rings, and other sealing products, and 10% is used to manufacture fuel line and intake pump insulators.

[0003] The hydrogenation process of nitrile rubber (NBR) generally employs a homogeneous hydrogenation method using noble metal catalysts. Compared to most non-noble metal catalysts (such as nickel naphthenate, alkylcobalt, and alkylaluminum), noble metal catalysts only hydrogenate the carbon-carbon double bonds in NBR, without hydrogenating the cyano groups. Homogeneous hydrogenation of NBR solutions uses Group VIII noble metals such as rhodium, palladium, ruthenium, ruthenium-rhodium, and ruthenium-palladium catalysts. The catalyst exists in molecular form in the polymer solution, activating hydrogen gas under its action to catalyze the hydrogenation reaction of the polymer.

[0004] After nitrile rubber is hydrogenated using a homogeneous hydrogenation method, the metal catalyst remains in the rubber solution, which reduces the aging performance of the nitrile rubber product and accelerates the aging rate. Therefore, it is necessary to remove it. Methods for removing catalysts from the homogeneous hydrogenation solution of unsaturated copolymers mainly include the solvent / kneading method with the addition of organic extractant, the precipitation method with the addition of organic compounds, and the ion exchange resin method. CN1313344A discloses a method for removing hydrogenation catalysts from unsaturated copolymers. Specifically, it discloses using an organic compound containing -NH2 or / and C=S as a complexing agent and a carboxylic acid as an extractant to convert the residual noble metal catalyst in the hydrogenation solution of the unsaturated copolymer into a metal-organic complex soluble in the aqueous extractant solution, which then enters the aqueous solution from the viscous copolymer hydrogenation solution. This method can achieve a one-time removal rate of over 98% for rhodium and over 77% for ruthenium in the hydrogenation solution. This method is also effective in solutions where bimetallic catalysts are used for homogeneous catalytic hydrogenation of polymer solutions. However, this method requires a large amount of extractant and a long reaction time. Summary of the Invention

[0005] The purpose of this invention is to provide a method for removing metal catalysts from the hydrolyzed solution of unsaturated polymers. Under the action of a high-voltage electric field, the metal catalysts in the hydrolyzed solution of unsaturated polymers are transferred from the oil phase to the aqueous phase, thereby achieving the removal of metal catalysts from the solution. The removal speed is fast and the removal rate is greater than 90%.

[0006] To achieve the above objectives, the present invention provides a method for removing metal catalysts from the colloidal solution after hydrogenation of unsaturated polymers, the method comprising:

[0007] (1) Mix the complexing agent, extractant and hydrogenated unsaturated polymer solution;

[0008] (2) The mixture obtained in step (1) is subjected to oil-water separation under a voltage of 200-2000V / cm.

[0009] A second aspect of the present invention provides an adhesive solution prepared by the method described in the first aspect.

[0010] The method of this invention removes metal catalysts from polymer solutions under a specific voltage, thereby improving the removal rate of metal catalysts, enhancing the separation effect between the oil and aqueous phases, shortening the operation cycle, and increasing separation efficiency. Furthermore, the method of this invention can further reduce the amount of extractant used. This method exhibits the same removal effect on metals in polymers of various viscosities, especially high viscosity polymers, is simple to operate, and has broad prospects for industrial application. Detailed Implementation

[0011] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0012] This invention provides a method for removing metal catalysts from the gel solution after hydrogenation of unsaturated polymers, the method comprising:

[0013] (1) Mix the complexing agent, extractant and hydrogenated unsaturated polymer solution;

[0014] (2) The mixture obtained in step (1) is subjected to oil-water separation under a voltage of 200-2000V / cm.

[0015] According to the present invention, preferably, the molar ratio of the complexing agent to the metal catalyst in the adhesive solution is 1:2-10 (e.g., 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, and any range of any two of the above values).

[0016] According to the present invention, there are no special requirements for the form in which the complexing agent is used, as long as it enables the complexing agent to react with the metal catalyst. Preferably, the complexing agent is used in solution form, and the content of the complexing agent in the solution is 0.01-10% by weight (e.g., 0.01% by weight, 0.1% by weight, 1% by weight, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, and any range of any two of the above values).

[0017] According to the present invention, the solvent in the complexing agent solution can be a solvent commonly used in the art, or any one or more organic solvents capable of dissolving unsaturated polymers. Preferably, the solvent in the complexing agent solution is a C6-C20 aromatic hydrocarbon or a halogenated aromatic hydrocarbon, more preferably at least one of toluene, xylene, chlorobenzene, dichlorobenzene and polychlorinated benzene.

[0018] According to the present invention, in order to improve the removal rate of metal catalysts, preferably, the complexing agent is at least one of organic compounds containing -SH and / or C=S groups; more preferably, the complexing agent is thiourea and / or thiols; and even more preferably, the thiols are at least one of ethanethiol, ethylenedithiol and 1-propanethiol.

[0019] According to the present invention, the amount of extractant can be selected in a wide range. Taking into account both the removal rate of metal catalyst and the utilization rate of raw materials, preferably, the volume ratio of extractant to liquid is 0.1-0.4:1 (e.g., 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, and any range of any two of the above values).

[0020] According to the present invention, preferably, the extractant is an aqueous solution of C1-C6 carboxylic acids and / or aminosulfonic acids; more preferably, the concentration of C1-C6 carboxylic acids and / or aminosulfonic acids in the extractant is 1-5% by weight (e.g., 1% by weight, 1.5% by weight, 2% by weight, 2.5% by weight, 3% by weight, 3.5% by weight, 4% by weight, 4.5% by weight, 5% by weight, and any range of any two of the above values).

[0021] According to the present invention, preferably, the C1-C6 carboxylic acid is at least one selected from citric acid, gluconic acid and propionic acid.

[0022] The present invention does not limit the type of unsaturated polymer, and can be any type of unsaturated polymer containing carbon-carbon double bonds that is common in the art. For example, the unsaturated polymer can preferably be a binary copolymer and / or a ternary copolymer.

[0023] Preferably, the binary copolymer is selected from at least one of butadiene-acrylonitrile copolymer, butadiene-methacrylonitrile copolymer, 2-methyl-1,3-butadiene-acrylonitrile copolymer, 2-methyl-1,3-butadiene-methacrylonitrile copolymer and styrene-butadiene-styrene block copolymer.

[0024] Preferably, the terpolymer is selected from at least one of butadiene-acrylonitrile-methacrylic acid copolymer, butadiene-methacrylonitrile-acrylic acid copolymer, butadiene-methacrylonitrile-methacrylic acid copolymer, and butadiene-acrylonitrile-acrylic acid copolymer.

[0025] According to the present invention, preferably, the degree of hydrogenation of the adhesive is 1-99%. The "degree of hydrogenation" is defined as the proportion of hydrogenated butadiene segments in the copolymer, and the test method is iodometric titration SH / T1763-2008.

[0026] According to the present invention, preferably, the viscosity of the adhesive solution is ≥10 centipoise.

[0027] According to the present invention, preferably, the dry rubber (e.g., hydrogenated nitrile rubber) content of the adhesive solution accounts for 1-20% by weight of the total weight of the adhesive solution.

[0028] According to the present invention, preferably, the content of the metal catalyst in the adhesive solution is 0.001-0.05% by weight of the total weight of the adhesive solution based on dry adhesive.

[0029] According to the present invention, preferably, the adhesive solution is a hydrogenated nitrile butadiene rubber adhesive solution. In this invention, there are no restrictions on the source of the hydrogenated nitrile butadiene rubber adhesive solution; it can be prepared by existing methods in the art. For example, the hydrogenated nitrile butadiene rubber adhesive solution can be obtained by the following preparation method: catalytic hydrogenation of an unsaturated polymer with a metal catalyst in a solvent under hydrogenation conditions to obtain the hydrogenated nitrile butadiene rubber adhesive solution. The present invention does not limit the hydrogenation conditions; the hydrogenation reaction conditions can be conventional hydrogenation reaction conditions in the art, and those skilled in the art can freely choose according to actual needs.

[0030] In this invention, the source of the metal catalyst is not limited; it can be commercially available or prepared using existing catalyst preparation methods. Preferably, the metal catalyst is selected from at least one of rhodium, ruthenium, and palladium. For example, the metal catalyst can be an organophosphorus chloride or an organobisphosphorus chloride of at least one of rhodium, ruthenium, and palladium.

[0031] According to the present invention, preferably, in step (2), the voltage is 500-2000V / cm.

[0032] According to the present invention, in order to further improve the removal rate of metal catalysts, preferably, the oil-water separation conditions further include: a temperature of 50-150°C and a time of 0.1-12h, preferably 0.2-1h.

[0033] A second aspect of the present invention provides an adhesive solution prepared by the method described in the first aspect.

[0034] The content of metal catalyst in the adhesive solution treated by the method of the present invention is even lower, and the content of metal catalyst in the adhesive solution after treatment is 0.1-10% of the content of metal catalyst in the adhesive solution before treatment.

[0035] The present invention will be described in detail below through embodiments. Unless otherwise stated, all raw materials involved in the following embodiments are commercially available products;

[0036] The ruthenium metal catalyst was purchased from Zhengzhou Alpha Chemical Co., Ltd.

[0037] The rhodium metal catalyst was purchased from Zhengzhou Alpha Chemical Co., Ltd.

[0038] The adhesive solution contains hydrogenated butadiene-acrylonitrile (butadiene-acrylonitrile copolymer) rubber, a metal catalyst, and a solvent (xylene).

[0039] Example 1

[0040] (1) The degree of hydrogenation of the adhesive solution is 90%, the viscosity is 58 centipoise, the content of hydrogenated nitrile rubber in the adhesive solution is 5% by weight, and the content of ruthenium metal catalyst is 0.05% by weight based on the dry rubber content. A xylene solution of ethanethiol (containing 2% by weight of ethanethiol) is added to 1000g of the adhesive solution, followed by an aqueous solution of citric acid (containing 3% by weight of citric acid). The mixture is thoroughly mixed using magnetic stirring. The molar ratio of ethanethiol to the metal catalyst in the adhesive solution is 1:3, and the volume ratio of the aqueous solution of citric acid to the adhesive solution is 0.2:1.

[0041] (2) After heating the mixture obtained in step (1) to 70°C, the oil and water phases were separated under a voltage of 500V / cm. After 0.5h, the ruthenium metal catalyst content in the upper oil phase was 0.0015% by weight based on the dry gum content.

[0042] Example 2

[0043] (1) The degree of hydrogenation of the adhesive solution is 99%, the viscosity is 15 centipoise, the content of hydrogenated nitrile rubber in the adhesive solution is 1% by weight, and the content of rhodium metal catalyst is 0.03% by weight based on the dry rubber content. A xylene solution of ethylene dithiol (containing 0.5% by weight of ethylene dithiol) is added to 1000g of the adhesive solution, followed by an aqueous solution of citric acid (containing 2% by weight of citric acid). The mixture is thoroughly mixed using magnetic stirring. The molar ratio of ethylene dithiol to the metal catalyst in the adhesive solution is 1:2, and the volume ratio of the aqueous solution of citric acid to the adhesive solution is 0.4:1.

[0044] (2) After heating the mixture obtained in step (1) to 60°C, the oil and water phases were separated under a voltage of 1000V / cm. After 0.5h, the rhodium metal catalyst content in the upper oil phase was 0.0023% by weight, calculated as dry gum content.

[0045] Example 3

[0046] (1) The degree of hydrogenation of the adhesive solution is 70%, the viscosity is 100 centipoise, the content of hydrogenated nitrile rubber in the adhesive solution is 10% by weight, and the content of rhodium metal catalyst is 0.02% by weight based on the dry rubber content. A xylene solution of 1-propanethiol (containing 0.1% by weight of 1-propanethiol) is added to 1000g of the adhesive solution, followed by an aqueous solution of citric acid (containing 3% by weight of citric acid). The mixture is thoroughly mixed using magnetic stirring. The molar ratio of 1-propanethiol to the metal catalyst in the adhesive solution is 1:2, and the volume ratio of the aqueous solution of citric acid to the adhesive solution is 0.2:1.

[0047] (2) After heating the mixture obtained in step (1) to 100°C, the oil and water phases were separated under a voltage of 2000V / cm. After 0.5h, the rhodium metal catalyst content in the upper oil phase was 0.0018% by weight, calculated as dry gum content.

[0048] Example 4

[0049] The method was carried out according to Example 1, except that the oil-water phase separation time was 0.2 h.

[0050] The ruthenium metal catalyst content in the upper oil phase, based on dry gum content, is 0.0045% by weight.

[0051] Example 5

[0052] The method was carried out according to Example 1, except that the mixture was added to the electro-desalination equipment at room temperature (about 25°C).

[0053] The ruthenium metal catalyst content in the upper oil phase, based on dry gum content, is 0.003% by weight.

[0054] Example 6

[0055] The procedure was carried out according to Example 1, except that ethanethiol was replaced with an equal mass of aqueous stannous chloride solution.

[0056] The ruthenium metal catalyst content in the upper oil phase, based on dry gum content, is 0.03% by weight.

[0057] Example 7

[0058] The procedure was carried out according to Example 1, except that citric acid was replaced with an equal mass of acetic acid.

[0059] The ruthenium metal catalyst content in the upper oil phase, calculated based on dry gum content, is 0.01%.

[0060] Example 8

[0061] The method was carried out according to Example 1, except that the mixture was heated to 200°C and then added to the electro-desalination equipment.

[0062] The ruthenium metal catalyst content in the upper oil phase, based on dry gum content, is 0.005% by weight.

[0063] Comparative Example 1

[0064] The method of Example 1 was followed, except that oil-water phase separation was performed under a voltage of 40 V / cm. The ruthenium metal catalyst content in the upper oil phase was 0.015% by weight, based on dry gum content.

[0065] As can be seen from the above embodiments, the method provided by the present invention can effectively remove precious metal (ruthenium, rhodium) catalysts from the adhesive solution. Furthermore, the preferred embodiments of the present invention (Examples 1-5) can achieve a removal rate of 91% for the precious metal catalyst in a relatively short time (within 0.5 hours) and with a small amount of extractant.

[0066] In addition, it should be noted that the comparative examples of the present invention are not prior art, but are only set up to highlight the specific method of the present invention, and should not be regarded as a limitation of the present invention.

[0067] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for removing metal catalysts from the gel solution after hydrogenation of unsaturated polymers, characterized in that, The method includes: (1) Mix the complexing agent, extractant and hydrogenated unsaturated polymer solution; (2) The mixture obtained in step (1) is subjected to oil-water separation under a voltage of 200-2000V / cm; The complexing agent is thiourea and / or thiols; The extractant is an aqueous solution of C1-C6 carboxylic acids and / or aminosulfonic acids; The concentration of C1-C6 carboxylic acids and / or aminosulfonic acids in the extractant is 1-5% by weight. The adhesive solution is a hydrogenated nitrile butadiene rubber adhesive solution; The metal catalyst is selected from at least one of rhodium, ruthenium, and palladium.

2. The method according to claim 1, wherein, The molar ratio of the complexing agent to the metal catalyst in the solution is 1:2-10; And / or, the complexing agent is used in solution form, wherein the content of the complexing agent in the solution is 0.01-10% by weight.

3. The method according to claim 1, wherein, The volume ratio of the extractant to the gel is 0.1-0.4:

1.

4. The method according to claim 1, wherein, The C1-C6 carboxylic acids are at least one of citric acid, gluconic acid, and propionic acid.

5. The method according to claim 1, wherein, The degree of hydrogenation of the adhesive solution is 1-99%; And / or, the viscosity of the adhesive solution is ≥10 centipoise; And / or, the dry adhesive content of the adhesive solution accounts for 1-20% by weight of the total weight of the adhesive solution. And / or, the content of the metal catalyst in the adhesive is 0.001-0.05% by weight of the total weight of the adhesive based on dry adhesive.

6. The method according to claim 1, wherein, In step (2), the voltage is 500-2000V / cm; And / or, the conditions for oil-water separation also include: a temperature of 50-150℃ and a time of 0.1-12h.

7. The method according to claim 1, wherein, The oil-water separation time is 0.2-1 hour.