Recycling method of gel in carboxylic butadiene-acrylonitrile latex, regenerated emulsion and application thereof

Abstract

The invention discloses a recycling method of gel in carboxylic butadiene-acrylonitrile latex, regenerated emulsion and application thereof, and relates to the technical field of hazardous waste treatment. The recycling method comprises the steps that gel, functional filler and a polar solvent are mixed and subjected to wet mixing, a composite glue solution is obtained, and the polar solvent comprises a mixed solvent of at least two of xylene, DMF, acetone, n-butyl alcohol, dimethyl sulfoxide, acetonitrile and ethyl acetate; part of the solvent in the composite adhesive solution is recycled, and the composite adhesive with the solid content larger than or equal to 75% is obtained. The functional filler can improve the performance of the latex, and the composite adhesive with high solid content can be obtained through solvent recovery. The prepared composite adhesive can be widely applied to the fields of adhesives, dipping latex or coatings and the like. Particularly, the invention also provides regenerated latex which can be applied to downstream products such as labor protection gloves and the like.

Description

Technical Field

[0001] The invention relates to the technical field of hazardous waste treatment, and in particular to a method for recycling gel in carboxylated nitrile latex, a regenerated emulsion and applications thereof. Background Art

[0002] Carboxylated nitrile latex is a very commonly used synthetic latex, mainly used to manufacture gloves, seals, hoses and other products with good wear resistance, heat resistance and oxidation resistance for oil and fuel.

[0003] A certain amount of gel will be produced in each stage of the carboxylated nitrile latex production process, especially in the later stage. Currently, the production of gel in the carboxylated nitrile latex production process is reduced by improving the preparation process. However, a certain amount of gel is still unavoidable, and the gel production rate is about 1%.

[0004] In latex production plants, gel is generally treated as hazardous waste and awaits recycling, with large amounts of it piled up in waste warehouses. The treatment cost of this gel is high and results in a large amount of waste of resources.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The invention aims to provide a method for recycling gel in carboxylated nitrile latex, a regenerated emulsion and application thereof.

[0007] The present invention is achieved in that:

[0008] In a first aspect, the present invention provides a method for recycling gel in carboxylated nitrile latex, comprising:

[0009] The gel, the functional filler and the polar solvent are mixed and wet-kneaded to obtain a composite glue solution, wherein the polar solvent includes a mixed solvent of at least two of xylene, DMF, acetone, n-butanol, dimethyl sulfoxide, acetonitrile and ethyl acetate;

[0010] Part of the solvent in the composite adhesive solution is recovered to obtain a composite adhesive with a solid content of ≥75%.

[0011] In an optional embodiment, the mass ratio of the gel, the functional filler and the polar solvent is 1:(0.4-0.6):(1.44-1.68).

[0012] In an optional embodiment, the wet mixing includes mixing and dissolving the gel with a portion of the polar solvent to form a gel solution, mixing and dispersing the functional filler with the remaining polar solvent to obtain a filler dispersion; wet mixing the gel solution and the filler dispersion to obtain a composite glue solution;

[0013] Preferably, the mass ratio of the gel to the polar solvent is 1:(1.4-1.6);

[0014] Preferably, the mass ratio of the functional filler to the remaining polar solvent is 1:(1-1.2).

[0015] In an optional embodiment, the polar solvent includes a mixed solvent of at least two of xylene, DMF, acetone, n-butanol, dimethyl sulfoxide, acetonitrile and ethyl acetate;

[0016] Preferably, the polar solvent is a mixed solvent of xylene, n-butanol and acetone;

[0017] Preferably, the mass ratio of the xylene, the n-butanol and the acetone is 1:(0.8-1.2):(1.6-2.4).

[0018] In an optional embodiment, the functional filler includes at least one of white carbon black, kaolin, carbon black and graphene.

[0019] In a second aspect, the present invention provides the use of a composite glue prepared by the method for recycling gel in carboxylated nitrile latex as described in any one of the above embodiments in the preparation of adhesives, impregnation emulsions or coatings.

[0020] In a third aspect, the present invention provides a regenerated emulsion, which includes a composite rubber prepared by the method for recycling gel in carboxylated nitrile latex described in any one of the above-mentioned embodiments.

[0021] In an optional embodiment, the method for preparing the regenerated emulsion comprises subjecting the composite glue, water and an emulsifier to a phase inversion emulsification reaction to obtain a regenerated emulsion having a solid content of ≥50%;

[0022] Preferably, the mass ratio of the composite glue, the water and the emulsifier is 100:(40-60):(3-5);

[0023] Preferably, the emulsifier includes at least one of sodium dodecylbenzene sulfonate, sodium dodecyl sulfate and potassium oleate.

[0024] In an optional embodiment, the phase inversion emulsification reaction includes preliminarily mixing the composite glue, the water and the emulsifier, and then mixing them at a rotation speed of 2000-4000 rpm for 30-60 minutes.

[0025] In a fourth aspect, the present invention provides the use of the regenerated emulsion as described in the aforementioned embodiment or a mixture of the regenerated emulsion as described in the aforementioned embodiment and carboxyl nitrile latex in the preparation of dipped gloves, latex coatings or latex pillows.

[0026] The present invention has the following beneficial effects:

[0027] The method for recycling gel in carboxylated nitrile latex provided by the present invention utilizes the byproduct gel produced in the production process of carboxylated nitrile latex as raw material, and compounds it with functional fillers in a polar solvent to play the role of wet mixing. The main function of wet mixing is to fully compound the gel macromolecules and the functional fillers in the organic solvent, so that the two are fully in contact and chemically bonded, wherein the functional fillers are conducive to improving the performance of the latex itself, and then the solvent is recovered to obtain a composite glue with a high solid content. The prepared composite glue can be widely used in the fields of adhesives, impregnated latex or coatings. In particular, the present invention also provides a regenerated latex, which is added with a suitable emulsifier and water to the composite glue to make the composite glue undergo a phase inversion emulsification reaction to regenerate an emulsion, and during the phase inversion emulsification reaction, the functional filler will be wrapped into the inside of the colloid particles, thereby achieving a better effect of improving the performance of the latex, wherein the phase inversion emulsification reaction only involves physical changes, not chemical changes, and the whole process is free of emulsion polymerization-related reactions, and finally a regenerated emulsion with a high solid content is obtained. The regenerated emulsion can be applied to downstream products such as labor protection gloves, such as nitrile flat gloves or dotted gloves. The invention reduces hazardous waste of enterprises and also generates certain economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 The present invention provides a process flow chart of the method for recycling gel in carboxylated nitrile latex. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0031] See also Figure 1 The present invention provides a method for recycling gel in carboxylated nitrile latex, which comprises: mixing gel, functional filler and polar solvent for wet kneading to obtain a composite rubber solution; recovering part of the solvent in the composite rubber solution to obtain a composite rubber with a solid content of ≥75%.

[0032] In the present invention, the byproduct gel produced in the production process of carboxylated nitrile latex is used as a raw material. After the production of carboxylated nitrile latex is completed, the gel can be filtered and collected by filtering the gel in the carboxylated nitrile latex of the finished product when it is transferred to the finished product kettle. The collected gel is compounded with a functional filler in a polar solvent to play the role of wet mixing. The main function of wet mixing is to fully compound the gel macromolecule and the functional filler in an organic solvent so that the two are fully contacted to produce chemical bonds, wherein the functional filler is conducive to improving the performance of the latex itself, and then the solvent is recovered to obtain a composite glue with a high solid content.

[0033] It should be understood that the production process of carboxylated nitrile latex is not specifically limited in the present invention, and any currently practicable process flow of carboxylated nitrile latex can be used, and the present invention only collects the gel produced therefrom.

[0034] Specifically, the present invention provides a method for recycling gel in carboxylated nitrile latex, comprising the following steps:

[0035] S1. Mix the gel, functional filler and polar solvent and perform wet mixing to obtain a composite glue solution.

[0036] In the present invention, the mass ratio of gel, functional filler and polar solvent is 1:(0.4-0.6):(1.44-1.68). Wet mixing refers to sufficient stirring and mixing in a polar solvent.

[0037] The functional filler includes but is not limited to at least one of white carbon black, kaolin, carbon black and graphene, preferably, the functional filler is white carbon black. The addition of the functional filler can enhance the performance of the latex itself.

[0038] The polar solvent includes but is not limited to a mixed solvent of at least two of xylene, DMF, acetone, n-butanol, dimethyl sulfoxide, acetonitrile and ethyl acetate; preferably, the polar solvent is a mixed solvent of xylene, n-butanol and acetone; more preferably, the mass ratio of xylene, n-butanol and acetone is 1:(0.8-1.2):(1.6-2.4).

[0039] At present, the most common wet mixing method is to make white carbon black into an aqueous dispersion and then mix it with natural latex. This method has a poor composite effect. In most cases, it only plays the role of a physical filler, and there is almost no cross-linking effect between white carbon black and the rubber itself. The key point of the present invention is the recovery of the gel during the production process. The gel is a solid dry gel, not a latex state, so it needs to be dissolved by a solvent and then emulsified into an oil-in-water emulsion state. Compounding with functional fillers in an organic solvent state makes cross-linking more likely to occur. And re-emulsification can break through the limitation that the solid content of conventional emulsion polymerization is difficult to exceed 50%, and it has strong applicability. It can not only save the cost of waste treatment, but also produce high-solid composite latex with special properties, which is in line with the development concept of green environmental protection.

[0040] In the present invention, by adding a functional filler into the gel, the two can be mixed in a polar solvent and cross-linked and composited, so that the functional filler is composited on the gel to achieve reinforcement of the composite gel solution.

[0041] In the present invention, by selecting and proportioning the polar solvent, the dissolution time can be controlled within one hour, which greatly shortens the dissolution time and improves the production efficiency. In addition, the entire gel can be completely dissolved without the situation where part of the gel is not dissolved, thereby improving the waste utilization rate. The gel, the functional filler and the polar solvent can be mixed together, or the gel and the functional filler can be mixed with the polar solvent separately, and then the two solutions are mixed.

[0042] Preferably, in the present invention, the gel is mixed and dissolved with a part of the polar solvent to form a gel solution, the functional filler is mixed and dispersed with the same remaining polar solvent to obtain a filler dispersion; the gel solution and the filler dispersion are wet-mixed to obtain a composite gel solution. The mass ratio of the gel to the part of the polar solvent is 1:(1.4-1.6); the mass ratio of the functional filler to the remaining polar solvent is 1:(1-1.2).

[0043] S2. Recover part of the solvent in the composite adhesive solution to obtain a composite adhesive with a solid content of ≥75%.

[0044] The method of recovering the solvent includes evaporation and concentration. The composite adhesive prepared by the above method can be widely used in the fields of adhesives, impregnated latex or coatings. When the composite adhesive is used to prepare impregnated gloves, the composite adhesive needs to be re-emulsified first.

[0045] Correspondingly, the present invention also provides a regenerated emulsion, which includes a composite rubber prepared by the above-mentioned method for recycling the gel in the carboxylated nitrile latex.

[0046] The preparation method comprises: subjecting the composite glue, water and an emulsifier to a phase inversion emulsification reaction to obtain a regenerated emulsion with a solid content of ≥50%.

[0047] The mass ratio of the composite rubber, water and emulsifier is 100:(40-60):(3-5), and the phase inversion emulsification reaction includes preliminarily mixing the composite rubber, water and emulsifier, and then mixing them at a speed of 2000-4000rpm for 30-60min. Through high-speed stirring and mixing, the composite rubber, water and emulsifier can be fully mixed to form water-in-oil regenerated latex.

[0048] Preferably, water includes but is not limited to at least one of deionized water, distilled water, pure water and ultrapure water, and the emulsifier includes but is not limited to at least one of sodium dodecylbenzene sulfonate, sodium dodecyl sulfate and potassium oleate.

[0049] It should be understood that some conventional auxiliary agents may be added during the phase inversion emulsification reaction, including but not limited to at least one of a defoamer, a wetting agent and a latex stabilizer. The specific selection of the above defoamers, wetting agents and latex stabilizers is not limited in the present invention, and any auxiliary agent that can achieve its corresponding effect can be used as the defoamer, wetting agent and latex stabilizer of the present application.

[0050] The present invention adds a suitable emulsifier and water to the composite rubber to make the composite rubber undergo a phase inversion emulsification reaction to regenerate an emulsion. During the phase inversion emulsification reaction, the functional filler will be wrapped into the interior of the rubber particles, thereby achieving a better effect of improving the performance of the latex. The phase inversion emulsification reaction only involves physical changes but no chemical changes, and no emulsion polymerization-related reactions are carried out in the entire process, thereby finally obtaining a regenerated emulsion with a high solid content.

[0051] The regenerated emulsion prepared by the above-mentioned method for recycling the gel in the carboxylated nitrile latex has the characteristics of oil-in-water and high solid content, and can be widely used in the preparation of dipped gloves, latex coatings or latex pillows. The regenerated emulsion can also be mixed with the carboxylated nitrile latex and then used to prepare dipped gloves, latex coatings or latex pillows, which can obtain better wear resistance and wear resistance. The present invention reduces the hazardous waste of enterprises and also generates certain economic value.

[0052] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0053] Example 1

[0054] The present embodiment provides a method for recycling gel in carboxylated nitrile latex, which comprises:

[0055] S1. Take 1 kg of gel produced in the production process of carboxylated nitrile latex, use a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone as a polar solvent, and dissolve the gel into a gel solution; the gel dissolves quickly in the polar solvent, and the dissolution time is about 1 hour, and the gel is completely dissolved. Disperse 50 g of white carbon black in 50 g of the same polar solvent to obtain 100 g of white carbon black dispersion; take the white carbon black dispersion and the filtered gel solution for wet mixing to prepare a composite glue solution.

[0056] S2. Concentrate the composite glue solution by evaporation to recover excess solvent, so that the solid content of the composite glue reaches 75% to 95%.

[0057] S3. Preliminarily mix 100 g of composite rubber, 50 g of deionized water, and 5 g of emulsifier (2.5 g of sodium dodecylbenzene sulfonate, 2 g of sodium dodecyl sulfate, and 0.5 g of potassium oleate) in a designated container; add the preliminarily mixed materials into a high-speed emulsifier for phase inversion emulsification reaction to prepare a regenerated emulsion with a solid content of about 60%.

[0058] Example 2

[0059] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, the polar solvent is replaced by a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone with 750 g of xylene and 750 g of acetone, and the gel dissolves faster in the mixed solution, and the dissolution time is 4 to 5 hours, and the gel is completely dissolved.

[0060] Example 3

[0061] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, the polar solvent is replaced by a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone with 750 g of xylene and 750 g of n-butanol. The gel dissolves faster in the mixed solution, and the dissolution time is 10 to 20 hours, and the gel is completely dissolved.

[0062] Example 4

[0063] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, the polar solvent is replaced by a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone with 750 g of n-butanol and 750 g of acetone, and the gel dissolves faster in the mixed solution, and the dissolution time is 5 to 10 hours, and the gel is completely dissolved.

[0064] Example 5

[0065] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, the polar solvent is replaced by a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone with 500 g of xylene, 500 g of n-butanol and 500 g of acetone; the gel dissolves faster in the mixed solution, and the dissolution time is about 3 hours, and the gel is completely dissolved.

[0066] Example 6

[0067] This embodiment is substantially the same as Embodiment 1, except that, in this embodiment, the amount of the white carbon black dispersion is changed from 100 g to 150 g (the ratio of the white carbon black to the polar solution is 1:1).

[0068] Example 7

[0069] This embodiment is substantially the same as Embodiment 1, except that, in this embodiment, the amount of the white carbon black dispersion is changed from 100 g to 200 g (the ratio of the white carbon black to the polar solution is 1:1).

[0070] Example 8

[0071] This embodiment is basically the same as Embodiment 1, except that, in this embodiment, the amount of the white carbon black dispersion is changed from 100 g to 150 g (the ratio of white carbon black to the polar solution is 1:1), and the solid content of the regenerated emulsion is changed from 60% to 50%.

[0072] Example 9

[0073] This embodiment is basically the same as Embodiment 1, except that the functional filler in this embodiment is kaolin.

[0074] The present embodiment provides a method for recycling gel in carboxylated nitrile latex, which comprises:

[0075] S1. Take 1 kg of gel produced in the production process of carboxylated nitrile latex, use a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone as a polar solvent, and dissolve the gel into a gel solution; the gel dissolves quickly in the polar solvent, the dissolution time is about 1 hour, and the gel is completely dissolved. Disperse 50 g of kaolin in 50 g of the same polar solvent to obtain 100 g of kaolin dispersion; take the kaolin dispersion and the filtered gel solution for wet mixing to make a composite glue solution.

[0076] S2. Concentrate the composite glue solution by evaporation to recover excess solvent, so that the solid content of the composite glue reaches 75% to 95%.

[0077] S3. Preliminarily mix 100 g of composite rubber, 50 g of deionized water, and 5 g of emulsifier (2.5 g of sodium dodecylbenzene sulfonate, 2 g of sodium dodecyl sulfate, and 0.5 g of potassium oleate) in a designated container; add the preliminarily mixed materials into a high-speed emulsifier for phase inversion emulsification reaction to prepare a regenerated emulsion with a solid content of about 60%.

[0078] Example 10

[0079] The present embodiment provides a method for recycling gel in carboxylated nitrile latex, which comprises:

[0080] S1. Take 1 kg of gel produced in the production process of carboxylated nitrile latex, use a mixture of 350 g of xylene, 350 g of n-butanol and 700 g of acetone as a polar solvent, and dissolve the gel into a gel solution; the gel dissolves quickly in the polar solvent, and the dissolution time is about 1 hour, and the gel is completely dissolved. Disperse 50 g of white carbon black in 60 g of the same polar solvent to obtain 110 g of white carbon black dispersion; take the white carbon black dispersion and the filtered gel solution for wet mixing to prepare a composite glue solution.

[0081] S2. Concentrate the composite glue solution by evaporation to recover excess solvent, so that the solid content of the composite glue reaches 75% to 95%.

[0082] S3. Preliminarily mix 100 g of composite rubber, 40 g of deionized water, and 3 g of emulsifier (1.5 g of sodium dodecylbenzene sulfonate, 1.2 g of sodium dodecyl sulfate, and 0.3 g of potassium oleate) in a designated container; add the preliminarily mixed materials into a high-speed emulsifier for phase inversion emulsification reaction to prepare a regenerated emulsion with a solid content of about 60%.

[0083] Embodiment 11

[0084] The present embodiment provides a method for recycling gel in carboxylated nitrile latex, which comprises:

[0085] S1. Take 1 kg of gel produced in the production process of carboxylated nitrile latex, use a mixture of 400 g of xylene, 400 g of n-butanol and 800 g of acetone as a polar solvent, and dissolve the gel into a gel solution; the gel dissolves quickly in the polar solvent, and the dissolution time is about 1 hour, and the gel is completely dissolved. Disperse 60 g of white carbon black in 60 g of the same polar solvent to obtain 120 g of white carbon black dispersion; wet-mix the white carbon black dispersion with the filtered gel solution to prepare a composite glue solution.

[0086] S2. Concentrate the composite glue solution by evaporation to recover excess solvent, so that the solid content of the composite glue reaches 75% to 95%.

[0087] S3. Preliminarily mix 100 g of composite rubber, 60 g of deionized water, and 4 g of emulsifier (2 g of sodium dodecylbenzene sulfonate, 1.6 g of sodium dodecyl sulfate, and 0.4 g of potassium oleate) in a designated container; add the preliminarily mixed materials into a high-speed emulsifier for phase inversion emulsification reaction to prepare a regenerated emulsion with a solid content of about 60%.

[0088] Comparative Example 1

[0089] This comparative example is basically the same as Example 1, except that in this comparative example, the polar solvent is replaced by 1.5 kg of xylene from a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone. The gel dissolves slowly in xylene, taking more than 20 hours to dissolve, and a small amount of gel remains undissolved.

[0090] Comparative Example 2

[0091] This comparative example is basically the same as Example 1, except that in this comparative example, the polar solvent is replaced by 1.5 kg of acetone from a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone. The gel dissolves slowly in acetone, and the dissolution time is 10 to 20 hours, and the gel is completely dissolved.

[0092] Comparative Example 3

[0093] This comparative example is basically the same as Example 1, except that in this comparative example, the polar solvent is replaced by 1.5 kg of n-butanol from a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone. The gel dissolves slowly in n-butanol and cannot be completely dissolved after treatment for more than 36 hours.

[0094] Comparative Example 4

[0095] This comparative example provides a carboxylated nitrile latex, and the latex used is carboxylated nitrile latex produced by Xingyu New Materials Co., Ltd., model number is XY802.

[0096] Comparative Example 5

[0097] This comparative example provides a mixture of carboxylated nitrile latex and white carbon black, wherein the amount of white carbon black added is 5% of the mass of the carboxylated nitrile latex.

[0098] Comparative Example 6

[0099] This comparative example is basically the same as Example 1, except that the steps related to white carbon black are omitted in this comparative example. The method provided in this comparative example specifically includes:

[0100] S1. Take 1 kg of gel produced in the production process of carboxylated nitrile latex, use a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone as a polar solvent, and dissolve the gel into a gel solution; the gel dissolves faster in the polar solvent, and the dissolution time is about 1 hour, and the gel is completely dissolved.

[0101] S2. Evaporating the gel solution to recover excess solvent, so that the solid content of the gel solution reaches 75-95%.

[0102] S3. Preliminarily mix 100 g of gel solution, 50 g of deionized water and 5 g of emulsifier in a designated container; add the preliminarily mixed materials into a high-speed emulsifier for phase inversion emulsification reaction to prepare a regenerated emulsion with a solid content of about 60%.

[0103] Comparative Example 7

[0104] This comparative example is basically the same as Example 1, except that step S2 of Example 1: recovering excess solvent is omitted in this comparative example. At this time, the solid content of the regenerated emulsion prepared is about 25%. The specific steps include:

[0105] S1. Take 1 kg of gel produced in the production process of carboxylated nitrile latex, use a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone as a polar solvent, and dissolve the gel into a gel solution; the gel dissolves quickly in the polar solvent, and the dissolution time is about 1 hour, and the gel is completely dissolved. Disperse 50 g of white carbon black in 50 g of the same polar solvent to obtain 100 g of white carbon black dispersion; take the white carbon black dispersion and the filtered gel solution for wet mixing to prepare a composite glue solution.

[0106] S2. Preliminarily mix 100 g of composite rubber, 50 g of deionized water and 5 g of emulsifier in a designated container; add the preliminarily mixed materials into a high-speed emulsifier for phase inversion emulsification reaction to prepare a regenerated emulsion with a solid content of about 25%.

[0107] Comparative Example 8

[0108] This comparative example is basically the same as Example 1, except that in step S2 of this comparative example, when recovering the solvent, the solid content of the composite rubber reaches 60%, and the solid content of the regenerated emulsion prepared at this time is about 35%. The specific steps include:

[0109] S1. Take 1 kg of gel produced in the production process of carboxylated nitrile latex, use a mixture of 375 g of xylene, 375 g of n-butanol and 750 g of acetone as a polar solvent, and dissolve the gel into a gel solution; the gel dissolves quickly in the polar solvent, and the dissolution time is about 1 hour, and the gel is completely dissolved. Disperse 50 g of white carbon black in 50 g of the same polar solvent to obtain 100 g of white carbon black dispersion; take the white carbon black dispersion and the filtered gel solution for wet mixing to prepare a composite glue solution.

[0110] S2. Concentrate the composite glue solution by evaporation to recover excess solvent, so that the solid content of the composite glue reaches 60%.

[0111] S3. Preliminarily mix 100 g of composite rubber, 50 g of deionized water and 5 g of emulsifier in a designated container; add the preliminarily mixed materials into a high-speed emulsifier for phase inversion emulsification reaction to prepare a regenerated emulsion with a solid content of about 35%.

[0112] Comparative Example 9

[0113] This comparative example is basically the same as Example 1, except that step S3 is omitted in this comparative example, and the composite adhesive is directly used as the final product.

[0114] Comparative Example 10

[0115] This comparative example is substantially the same as Example 1, except that the emulsifier in this comparative example is only potassium oleate.

[0116] Experimental Example 1

[0117] The effect of different polar solvents on gel dissolution was tested. Please refer to Table 1 for the test results.

[0118] Table 1. Statistical table of the effect of different polar solvents on gel dissolution

[0119] Example Solvent selection Dissolution time Dissolved state Example 1 Xylene: n-butanol: acetone = 1:1:2 <1h Completely dissolved Example 2 Xylene: acetone = 1:1 4～5h Completely dissolved Example 3 Xylene: n-butanol = 1:1 10～20h Completely dissolved Example 4 n-Butanol:acetone=1:1 5～10h Completely dissolved Example 5 Xylene: n-butanol: acetone = 1:1:1 3h Completely dissolved Comparative Example 1 Xylene >20h A small amount of gel is not dissolved Comparative Example 2 acetone 10～20h Completely dissolved Comparative Example 3 n-Butanol >36h Poor solubility

[0120] Experimental Example 2

[0121] The emulsions provided in the above Examples 1-11 and Comparative Examples 1-10 were used to prepare different glove products according to the following two processes:

[0122] Process (1): vulcanizing the latex according to a labor protection vulcanization formula (100 parts of nitrile latex, 1.0 parts of sulfur, 2.5 parts of zinc oxide, 0.5 parts of ZDC, and 0.5 parts of BZ); placing the vulcanized mixed latex at room temperature for 48 hours, and then mixing the latex according to a mixing formula (0.5 parts of blue paste, 1 part of casein, and 1.5 parts of CMC), and making a sample to obtain a nitrile flat glove;

[0123] Process (2): the emulsion and conventional nitrile latex are mixed in a designated container in a ratio of 1:1 to obtain a mixed latex, and the mixed latex is vulcanized according to a labor protection vulcanization formula (100 parts of nitrile latex, 1.0 parts of sulfur, 2.5 parts of zinc oxide, 0.5 parts of ZDC, and 0.5 parts of BZ); the vulcanized mixed latex is placed at room temperature for 48 hours, and then the mixture is adjusted according to a rubber adjustment formula (0.5 parts of blue paste, 1 part of casein, and 1.5 parts of CMC), and proofing is performed to obtain nitrile flat gloves;

[0124] The prepared nitrile flat gloves were subjected to wear resistance test and other performance tests. Please refer to the following table for the test results:

[0125] Table 2. Statistical table of wear resistance and penetration resistance of gloves prepared in different examples

[0126] Emulsion Example Preparation process Wear resistance / rotation Wear resistance / h Example 1 Crafts (1) 15500 13 Example 2 Crafts (1) 15000 12 Example 3 Crafts (1) 13000 10 Example 4 Crafts (1) 14000 11 Example 5 Crafts (1) 15500 13 Example 6 Crafts (1) 20000 16 Example 7 Crafts (1) 18000 15.5 Example 8 Crafts (1) 17600 16.5 Example 9 Crafts (1) 14000 11 Example 10 Crafts (1) 14500 11 Embodiment 11 Crafts (1) 15000 12 Comparative Example 1 Crafts (1) 8000 8 Comparative Example 2 Crafts (1) 13000 10 Comparative Example 3 Crafts (1) 6000 5 Comparative Example 4 Crafts (1) 12000 7 Comparative Example 5 Crafts (1) 8000 5 Comparative Example 6 Crafts (1) 10000 6 Comparative Example 7 Crafts (1) 5000 3 Comparative Example 8 Crafts (1) 6000 3 Comparative Example 9 Crafts (1) Unable to craft gloves Unable to craft gloves Comparative Example 10 Crafts (1) 13500 12

[0127] As can be seen from the above table, the regenerated emulsion prepared by the method for recycling gel in carboxy nitrile latex provided by the present invention has significantly better wear resistance and wear resistance when preparing nitrile flat gloves than the direct use of carboxy nitrile latex in Comparative Example 4, which is based on the chemical bond between functional filler white carbon black and rubber macromolecules during wet mixing. Improve the performance of the regenerated latex itself. In Comparative Examples 1-3, the choice of polar solvent is changed, which not only leads to a slow dissolution rate of the gel, but also causes the wear resistance and wear resistance of the gloves finally prepared to be significantly lower than that of Example 1. In Comparative Example 5, carboxy nitrile latex and white carbon black are directly mixed. At this time, white carbon black only plays the role of filler, and it cannot strengthen the carboxy nitrile latex, resulting in the wear resistance and wear resistance of the gloves finally prepared to be significantly lower than that of Example 1. White carbon black is omitted in Comparative Example 6. At this time, the wear resistance and wear resistance of the regenerated emulsion are reduced, but still higher than the effect in Comparative Example 5. This is because the performance of the gel is further enhanced after phase inversion emulsification. In Comparative Examples 7 and 8, the solid content of the composite rubber during solvent recovery was changed, resulting in changes in the solid content of the final regenerated emulsion. It can be seen that when the solid content of the regenerated emulsion is low, its performance is significantly reduced. In Comparative Example 9, the composite rubber is directly used as the final product, and the composite rubber is not subjected to phase inversion emulsification, which will cause the composite rubber to be in a phase separation state and cannot be used to prepare gloves. In Comparative Example 10, only potassium oleate is selected for emulsification, which will slightly reduce the wear resistance compared with Example 1, but the overall effect is still better than other comparative examples.

[0128] In addition, in Example 8, the effect of preparing nitrile flat gloves by mixing the regenerated emulsion and carboxyl nitrile latex in a ratio of 1:1 according to process (2) is better than the effect of preparing nitrile flat gloves by using the regenerated emulsion and carboxyl nitrile latex alone according to process (1). This fully demonstrates that the regenerated emulsion can be compounded with carboxyl nitrile latex for use.

[0129] In addition, the regenerated emulsion prepared in Example 6 was vulcanized and adjusted according to the nitrile bead glue process to prepare bead gloves. The beads of the obtained bead gloves fit well and the beads were full in shape. This shows that the regenerated emulsion provided by the present invention is not only suitable for preparing nitrile flat gloves, but also suitable for preparing bead gloves, and has a wide range of applications.

[0130] In summary, the method for recycling gel in carboxylated nitrile latex provided by the present invention utilizes the byproduct gel produced in the production process of carboxylated nitrile latex as a raw material, and compounds it with a functional filler in a polar solvent to play the role of wet mixing. The main function of wet mixing is to fully compound the gel macromolecule and the functional filler in an organic solvent, so that the two are fully in contact and chemically bonded, wherein the functional filler is conducive to improving the performance of the latex itself, and then the solvent is recovered to obtain a composite glue with a high solid content. The prepared composite glue can be widely used in the fields of adhesives, impregnated latex or coatings. In particular, the present invention also provides a regenerated latex, which is added with a suitable emulsifier and water to the composite glue to make the composite glue undergo a phase inversion emulsification reaction to regenerate an emulsion. During the phase inversion emulsification reaction, the functional filler will be wrapped into the interior of the colloid particles, thereby achieving a better effect of improving the performance of the latex, wherein the phase inversion emulsification reaction only involves physical changes, not chemical changes, and the whole process is free of emulsion polymerization-related reactions, and finally a regenerated emulsion with a high solid content is obtained. The regenerated emulsion can be applied to downstream products such as labor protection gloves, such as nitrile flat gloves or dotted gloves. The invention reduces hazardous waste of enterprises and also generates certain economic value.

[0131] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for recycling gel in carboxylated nitrile latex, characterized in that: It includes: The gel, the functional filler and the polar solvent are mixed and wet-kneaded to obtain a composite glue solution, wherein the polar solvent includes a mixed solvent of at least two of xylene, DMF, acetone, n-butanol, dimethyl sulfoxide, acetonitrile and ethyl acetate; Part of the solvent in the composite adhesive solution is recovered to obtain a composite adhesive with a solid content of ≥75%.

2. The method for recycling gel in carboxylated nitrile latex according to claim 1, wherein: The mass ratio of the gel, the functional filler and the polar solvent is 1:(0.4-0.6):(1.44-1.68).

3. The method for recycling gel in carboxylated nitrile latex according to claim 1, characterized in that: The wet mixing includes mixing and dissolving the gel with a portion of the polar solvent to form a gel solution, mixing and dispersing the functional filler with the remaining polar solvent to obtain a filler dispersion; wet mixing the gel solution and the filler dispersion to obtain a composite glue solution; Preferably, the mass ratio of the gel to the polar solvent is 1:(1.4-1.6); Preferably, the mass ratio of the functional filler to the remaining polar solvent is 1:(1-1.2).

4. The method for recycling gel in carboxylated nitrile latex according to claim 1, characterized in that: The polar solvent is a mixed solvent of xylene, n-butanol and acetone; Preferably, the mass ratio of the xylene, the n-butanol and the acetone is 1:(0.8-1.2):(1.6-2.4).

5. The method for recycling gel in carboxylated nitrile latex according to claim 1, characterized in that: The functional filler includes at least one of white carbon black, kaolin, carbon black and graphene.

6. Application of the composite glue prepared by the method for recycling gel in carboxylated nitrile latex as claimed in any one of claims 1 to 5 in the preparation of adhesives, impregnating emulsions or coatings.

7. A regeneration emulsion, characterized in that The invention comprises a composite rubber prepared by the method for recycling gel in carboxylated nitrile latex as described in any one of claims 1 to 5.

8. The regeneration emulsion according to claim 7, characterized in that The preparation method of the regenerated emulsion comprises subjecting the composite rubber, water and an emulsifier to a phase inversion emulsification reaction to obtain a regenerated emulsion with a solid content of ≥50%; Preferably, the mass ratio of the composite glue, the water and the emulsifier is 100:(40-60):(3-5); Preferably, the emulsifier includes at least one of sodium dodecylbenzene sulfonate, sodium dodecyl sulfate and potassium oleate.

9. The regeneration emulsion according to claim 8, characterized in that The phase inversion emulsification reaction includes preliminarily mixing the composite rubber, the water and the emulsifier, and then mixing them at a rotation speed of 2000-4000 rpm for 30-60 minutes.

10. Use of the regenerated emulsion as claimed in any one of claims 7 to 9 or a mixture of the regenerated emulsion as claimed in any one of claims 7 to 9 and carboxylated nitrile latex in the preparation of dipped gloves, latex coatings or latex pillows.

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