CN115926276A - Recyclable environment-friendly rubber sole material and preparation method and recycling method thereof - Google Patents

Abstract

The invention provides a recyclable environment-friendly rubber sole material and a preparation method and a recycling method thereof. The recyclable environment-friendly rubber sole material is prepared from raw materials including carboxyl functionalized rubber, a cross-linking agent, an anti-aging agent, a reinforcing agent and a plasticizer; the recovery method comprises the steps of crushing the recyclable environment-friendly rubber sole material, hydrolyzing with a hydrolysis solution, and drying a hydrolyzed product; the invention takes carboxyl on a main chain of carboxyl functionalized rubber as a crosslinking point to react with an epoxy functional group on glycidylamine epoxy resin to form a beta-hydroxyl ester bond crosslinking bond, and the beta-hydroxyl ester bond formed by the crosslinking reaction can be hydrolyzed in an alcohol aqueous solution with certain pH value and is recycled in a closed loop manner. The invention does not need other vulcanization aids, has simple system, good autocatalysis effect of the used cross-linking agent and quick and efficient reaction; the hydrolysis method has low toxicity, environmental protection, good effect and simple and convenient recovery.

Description

Recyclable environment-friendly rubber sole material and preparation method and recycling method thereof

Technical Field

The invention relates to the technical field of rubber materials, in particular to a recyclable environment-friendly rubber sole material and a preparation method and a recycling method thereof.

Background

The first type of the traditional rubber sole formula is a sulfur vulcanization system which takes sulfur as a vulcanizing agent, some nitrogen-containing substances and sulfur substances as accelerators, zinc oxide (ZnO) and Stearic Acid (SA) as activators and some other processing aids as main bodies. Such systems are complex in formulation design and the added adjuvants are often toxic to humans or harmful to the environment, such as: the CZ is promoted to have anaphylactic reaction on human skin; d is promoted to be toxic to human bodies; znO is harmful to aquatic organisms; associated with toxic fumes such as sulfur dioxide (SO) during high temperature vulcanization ₂ ) Carbon disulfide (CS) ₂ ) And the generation of VOCs gas which has serious harm to the health of rubber sole production workers. A second conventional rubber sole formulation is a peroxide crosslinking system represented by dicumyl peroxide (DCP). The system is high in vulcanization speed, but the vulcanized rubber has serious smell, so that the wearing experience of customers is seriously influenced when the vulcanized rubber is used as a sole material, and meanwhile, most of peroxides used as raw materials are toxic and high in activity, and potential safety hazards exist in the transportation process.

Aiming at the design of a green crosslinking system, the concept of introducing carboxyl/epoxy into a rubber main chain as a crosslinking point and designing a crosslinking reaction by taking a multifunctional epoxy small molecule/carboxylic acid molecule as a crosslinking agent is mainly designed based on an idea of an epoxy-acid reaction, and the idea is already applied to various commercialized rubbers, such as: a green crosslinking system of carboxylated nitrile rubber and epoxidized soybean oil; a green cross-linked system of Epoxidized Natural Rubber (ENR) and sebacic acid. However, these systems have a general problem that the reaction rate is low and a catalyst such as imidazole is required to be added.

China is a large consumption country of rubber shoes, and according to incomplete statistics, nearly 1 hundred million pairs of waste rubber shoes can not be effectively recycled and treated every year. The reason is that most of three-dimensional cross-linked networks generated by the traditional rubber sole vulcanization process are based on-S-S-bonds, -C-S-bonds and-C-C-bonds, and the chemical bonds are irreversible cross-linked bonds, so that the vulcanized rubber network is 'infusible and insoluble', the recovery of the rubber material of the sole is mainly carried out by crushing the waste rubber material and paving the crushed waste rubber material or burning the crushed waste rubber material as fuel at present, and the methods cannot realize 'high-value recovery' of the rubber material.

At present, based on a double-screw desulfurization technology, a method for realizing rubber desulfurization and recycling on a double-screw extruder through high temperature and strong shearing action is effectively popularized. Although the method can realize the desulfurization recovery of the traditional waste rubber, the molecular weight of the obtained reclaimed rubber is seriously reduced, and the Mooney rebound phenomenon exists, and the problems seriously restrict the wide utilization of the reclaimed rubber.

Therefore, a novel green recyclable environment-friendly rubber sole formula needs to be designed, and the formula can meet the following requirements: firstly, the formula is simple and practical, and can avoid the generation of unpleasant smell and toxic gas while avoiding the use of a large amount of toxic auxiliary agents; secondly, compared with other green vulcanization formulas, the formula has the advantages that the crosslinking reaction is rapid, and the obtained crosslinked elastomer has high effective crosslinking degree; thirdly, the rubber insole products produced by the formula can be effectively subjected to crosslinking decrosslinking through physical and chemical methods, the recovery process is green and environment-friendly, and meanwhile, the products obtained after recovery can be completely used for remanufacturing soles.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides a recyclable environment-friendly rubber sole material and a preparation method and a recycling method thereof.

The invention provides a formula based on taking carboxyl functionalized rubber as a rubber sole base material, taking carboxyl on a rubber main chain as a crosslinking point, and reacting with an epoxy functional group on commercial nitrogen-containing epoxy resin, mainly glycidyl amine epoxy resin, to form a beta-hydroxy ester bond crosslinking bond. The beta-hydroxy ester bond formed after the cross-linking reaction can be hydrolyzed under the catalysis of acid and alkali in the aqueous solution of ethanol to obtain the corresponding carboxyl functional rubber which is recovered in a closed loop, and the recovered rubber is used as the base rubber of the sole material for reprocessing.

According to the invention, only the glycidol amine epoxy resin is required to be added as a vulcanizing agent, and other vulcanizing auxiliaries are not required, so that the system is simple; in the vulcanization process, the molecules of the glycidylamine epoxy resin have 3 or more than high-activity epoxy groups, and meanwhile, an internal tertiary amine structure can be used as an internal catalyst for an epoxy-acid reaction, so that the reaction is fast and efficient.

One purpose of the invention is to provide a recyclable environment-friendly rubber sole material.

The recyclable environment-friendly rubber sole material is prepared from raw materials including carboxyl functionalized rubber, a cross-linking agent, an anti-aging agent and a reinforcing agent; preferably, the raw materials also comprise a plasticizer;

based on 100 parts by weight of the carboxyl-functional rubber,

in a preferred embodiment of the present invention,

the carboxyl functional rubber is at least one of copolymer rubber containing carboxyl functional group monomers, maleic anhydride graft modified rubber and carboxyl graft modified rubber;

the copolymer adhesive containing carboxyl functional groups is at least one of acrylonitrile-butadiene-methacrylic acid copolymer adhesive, acrylonitrile-butadiene-acrylic acid copolymer adhesive, styrene-butadiene-methacrylic acid copolymer adhesive, styrene-butadiene-acrylic acid copolymer adhesive, isoprene-methacrylic acid copolymer adhesive, isoprene acrylic acid copolymer adhesive, butadiene-methacrylic acid copolymer adhesive, butadiene-acrylic acid copolymer adhesive, butadiene-isobutylene-methacrylic acid copolymer adhesive, butadiene-isobutylene-acrylic acid copolymer adhesive, ethylene-propylene-methacrylic acid copolymer adhesive and ethylene-propylene-acrylic acid copolymer adhesive;

wherein the mass of the monomer containing the carboxyl functional group accounts for 0.1-40 percent of the total mass of the copolymer rubber, and preferably 3-10 percent; that is, the ratio of the mass amount of the monomer having a carboxyl functional group to the mass amount of the monomer not having a carboxyl functional group is from 0.1;

the maleic acid grafted modified rubber is at least one of maleic anhydride grafted modified nitrile rubber, maleic anhydride grafted modified styrene-butadiene rubber, maleic anhydride grafted modified natural rubber, maleic anhydride grafted modified ethylene propylene diene monomer rubber, maleic anhydride grafted modified butyl rubber and hydrolysis products of the maleic anhydride grafted modified butyl rubber and the maleic anhydride grafted modified butyl rubber;

wherein the grafting rate of the maleic anhydride is 0.1-40%, preferably 3-35%;

the carboxyl grafted modified rubber is at least one of thioglycollic acid grafted styrene-butadiene rubber, mercaptopropionic acid grafted styrene-butadiene rubber, thioglycollic acid grafted butadiene rubber and mercaptopropionic acid grafted butadiene rubber;

wherein the grafting ratio of the mercapto acid is 0.5 to 50 percent, and preferably 2 to 35 percent.

In a preferred embodiment of the present invention,

the cross-linking agent is glycidyl amine epoxy resin, preferably at least one of triglycidyl-p-aminophenol (TPAP), triglycidyl isocyanurate (TGIC), tetraglycidyl xylene diamine (TGXDA) and tetraglycidyl-1, 3-bisaminomethylcyclohexane (TGBAMCH).

In a preferred embodiment of the present invention,

the anti-aging agent is at least one of an anti-aging agent AW (ethoxyquinoline, 6-ethoxy-2, 4-trimethyl-1, 2-dihydroquinoline), an anti-aging agent D (N-phenyl-2-naphthylamine), an anti-aging agent H (N, N '-diphenyl-p-phenylenediamine), an anti-aging agent 4020 (N- (1, 3-dimethyl) butyl-N' -phenyl-p-phenylenediamine), an anti-aging agent 4010NA (N-isopropyl-N '-phenyl-p-phenylenediamine), an anti-aging agent BLE (9, 9-dimethylacridine), an anti-aging agent RD (2, 4-trimethyl-1, 2-dihydroquinoline polymer) and an anti-aging agent 2246 (2, 2' -methylenebis (4-methyl-6-tert-butylphenol)); and/or the presence of a gas in the gas,

the reinforcing agent is at least one of carbon black, calcium carbonate, white carbon black, talcum powder, kaolin and titanium dioxide; and/or the presence of a gas in the gas,

the plasticizer is at least one of operation oil, paraffin, coal tar, coumarone resin and polyester plasticizer.

The invention also aims to provide a preparation method of the recyclable environment-friendly rubber sole material, which comprises the following steps:

plasticating the carboxyl functionalized rubber, adding an anti-aging agent, a reinforcing agent and a crosslinking agent, adding or not adding a plasticizer, uniformly mixing and vulcanizing to obtain the recyclable environment-friendly rubber sole material.

In a preferred embodiment of the present invention,

the vulcanization temperature is 150-220 ℃, and preferably 150-190 ℃;

the vulcanization time is 5min to 60min, preferably 10min to 35min.

The invention also aims to provide a method for recycling the recyclable environment-friendly rubber sole material, which comprises the following steps:

crushing the recyclable environment-friendly rubber sole material, hydrolyzing with a hydrolysis solution, washing and drying a hydrolyzed product.

The alkaline hydrolysate can be used for hydrolysis and then can be acidified and then dried, wherein the acidification refers to a process of adding hydrochloric acid (the mol amount of HCl is the same as that of alkali, and the concentration of HCl solution is 0.5 mol/L) with the same amount as that of alkaline substances in the hydrolysate to neutralize the alkali in the hydrolysate after hydrolysis under the condition of the alkaline hydrolysate; the acidification step is only carried out when the alkali is sodium hydroxide, potassium hydroxide, lithium hydroxide, trimethylamine, triethylamine, dimethylamine, diethylamine, sodium alkoxide and potassium alkoxide, and the acidification step is not needed when the alkali is acidic hydrolysate; then, a large amount of deionized water is used for washing and then drying.

The recycled product is rubber raw rubber, the performance of the rubber raw rubber is equivalent to that of the original carboxyl functionalized rubber, and the recyclable environment-friendly rubber sole material can be prepared by adding raw materials such as a cross-linking agent, an anti-aging agent, a reinforcing agent, a plasticizer and the like according to the preparation method of the recyclable environment-friendly rubber sole material, uniformly mixing and vulcanizing.

In a preferred embodiment of the present invention,

the recyclable environment-friendly rubber sole material is crushed into particles with the particle size of 0.1-5 mm, preferably 0.1-2 mm;

the hydrolysate is prepared by mixing alkali or acid, water and alcohol;

the hydrolysate is preferably alkaline hydrolysate containing metal cations, and when the hydrolysate is alkaline hydrolysate and contains Na ⁺ 、K ⁺ 、Li ⁺ When metal cations are used, the ionic bond can be formed with glue containing carboxyl, has a function of sacrificing the bond, and improves the tensile mechanical property of the rubber to a certain extent;

wherein the volume ratio of water to alcohol is 1;

the acid-base concentration of the hydrolysate is 0.1-5 mol/L, preferably 0.5-2mol/L;

the hydrolysis temperature is 50-90 ℃, and preferably 60-80 ℃;

the hydrolysis time is 6 to 18 hours, preferably 9 to 18 hours.

In a preferred embodiment of the present invention,

the alcohol is at least one of methanol, ethanol, butanol and isopropanol; and/or the presence of a gas in the gas,

the alkali is at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, trimethylamine, triethylamine, dimethylamine, diethylamine, sodium alkoxide and potassium alkoxide; and/or the presence of a gas in the gas,

the acid is at least one of hydrogen chloride, hydrogen bromide, hydrogen iodide and sulfuric acid.

The invention can adopt the following technical scheme:

weighing the raw materials according to the proportion;

(1) The preparation method of the recyclable environment-friendly rubber sole material comprises the following steps:

A. coupling a carboxyl functional rubber to

Plasticating for three times on a model open mill;

B. setting the temperature of the internal mixer: 60 to 100 ℃; preferably: 70 to 90 ℃;

C. setting the rotating speed of the internal mixer: 40-60 r/min; preferably: 45-55 r/min;

D. adding the plasticated carboxyl functional rubber into an internal mixer for mixing, wherein the mixing time is as follows: 1-5 min; preferably: 2-3 min;

E. adding an anti-aging agent, and mixing for 30 s-3 min, preferably: 1-2 min;

F. adding a plasticizer for mixing for 30 s-3 min, preferably: 1-2 min;

G. adding the reinforcing agent for mixing twice, wherein the mixing time is 4-12 min, and preferably: 6-10 min;

H. taking out the rubber compound from the internal mixer, adjusting the roll spacing of the open mill to be 0.5mm, keeping the roll temperature to be 50 ℃, and controlling the rotation speed ratio of the front roller to the rear roller to be 1.5, wherein the ratio of the rubber compound to the rubber compound in the internal mixer is as follows

Plasticating for three times on a type open mill, then adjusting the roller spacing to be 0.8mm to enable a rubber to wrap a roller, adding a cross-linking agent, cutting for 4 times, alternately beating 12 triangular bags and 6 rolls so as to uniformly disperse small materials, and then discharging sheets;

I. the pressure of a vulcanizing press is 15MPa;

J. vulcanization temperature: 150 to 220 ℃; preferably: 150 to 190 ℃;

K. and (3) vulcanizing time: 5-60 min; preferably: 10-35 min.

(2) Hydrolytic recovery and reprocessing of samples

A. Crushing the vulcanized sole sample into particles with the particle size of 0.1-5 mm; preferably: 0.1-2 mm;

B. preparing hydrolysate, wherein the volume ratio of deionized water to alcohol is 1; preferably: 1;

C. preparing hydrolysate with acid-base concentration of 0.1-5 mol/L; preferably: 0.5-2mol/L;

D. setting the hydrolysis temperature to be 50-90 ℃; preferably: 60 to 80 ℃;

E. setting the hydrolysis time to be 6-18 h; preferably, the following components: 9-18 h;

F. drying the hydrolyzed product, adding the cross-linking agent again on a double-roller mill by the method H in the step (1) for mixing, and preparing a sole sample piece after repeated processing by the method I-K in the step (1);

the range of the cross-linking agent is the same as that of the cross-linking agent used for preparing the recyclable environment-friendly rubber sole material;

the alcohol in B is at least one of methanol, ethanol, butanol and isopropanol;

the alkali in the step C is at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, trimethylamine, triethylamine, dimethylamine, diethylamine, sodium alkoxide and potassium alkoxide;

the acid in C is at least one of hydrogen chloride, hydrogen bromide, hydrogen iodide and sulfuric acid.

The present invention is based on the principle of the "epoxy and acid" reaction, which generally requires a catalyst, otherwise the crosslinking reaction proceeds very slowly, among which catalysts containing tertiary amine groups, such as 1, 2-dimethylimidazole, are the predominant catalysts, and the catalytic principle is to catalyze the reaction by the formation of zwitterions with the epoxy-type crosslinker. The cross-linking agent of the invention contains tertiary amine groups, and can carry out internal catalysis on the reaction, thereby forming a catalyst-free rapid and efficient cross-linking system. The crosslinking agents used in the invention all contain tertiary amine group crosslinking agents, and the functionality is not less than 3, by using the crosslinking agents, the use of a crosslinking catalyst is omitted (the crosslinking catalyst is mostly toxic), the use of toxic substances is reduced, a vulcanization system is simplified, the crosslinking agents containing the tertiary amine group have an autocatalysis effect during vulcanization crosslinking reaction, the crosslinking reaction can be rapidly carried out without the catalyst, and meanwhile, the glycidyl amine epoxy crosslinking agents are all high-functionality crosslinking agents, and compared with the common epoxy resin crosslinking agents, more effective crosslinking can be formed under the condition of the same dosage, and the crosslinking effect is more efficient.

Meanwhile, according to the autocatalysis principle, the catalytic effect is that two molecules of cross-linking agents form zwitterions, wherein a tertiary amine group of one molecule of cross-linking agent is combined with an epoxy group of the other molecule of cross-linking agent to form zwitterions, the zwitterions are combined with carboxyl in the carboxyl functionalized rubber to form a five-membered ring transition state, then the molecule of cross-linking agent serving as a catalytic action leaves, and epoxy and acid are combined to generate an ester bond cross-linking bond. The tertiary amine functional group is positively charged, and if good catalytic benefit is to be achieved, the N + ion of the tertiary amine needs to be stabilized, i.e. the group directly adjacent to the tertiary amine group needs to contain an electron-withdrawing group, so that two factors need to be considered when selecting the glycidylamine epoxy cross-linking agent: one factor is that the groups directly adjacent to the tertiary amine groups preferably have an electron-withdrawing effect, and a better catalytic effect; and the other factor is that a cross-linking agent with low toxicity is selected as much as possible, so that the environment is protected. Based on the above factors, four glycidylamine-based epoxy crosslinking agents are preferred in the present invention.

The method for decrosslinking the carboxyl functional rubber crosslinked elastomer by using the micromolecule alcohol solution with a certain pH value is also specific to the invention, and toxic organic reagents such as tetrahydrofuran, acetone and the like are mostly used as reaction media in the existing recovery technology.

Compared with the common de-crosslinking method, the de-crosslinking method has low toxicity and is more environment-friendly and can achieve the same hydrolysis effect; because the rubber molecules only swell and do not dissolve in the alcohol solution, compared with organic reagents such as tetrahydrofuran, acetone and the like, the hydrolyzed rubber does not need to be flocculated by solvents such as ethanol and the like, and the recovery is simpler and more convenient.

Compared with the prior art, the invention has the beneficial effects that:

(1) The glycidyl amine epoxy resin cross-linking agent used in the invention has an autocatalysis effect, can rapidly carry out cross-linking reaction without a catalyst, and has large functionality and higher reactivity because the epoxy group of the cross-linking agent is positioned at the end of a molecular chain, so that more effective cross-links are formed; the vulcanization time of the invention is equivalent to that of a peroxide vulcanization system, and is greatly shortened compared with the vulcanization time of a vulcanization system taking glycidyl ether epoxy resin as a cross-linking agent;

(2) Besides the used glycidyl amine epoxy resin cross-linking agent, the invention does not need to add any toxic promoter, activator and other reaction auxiliary agents, and has simple system, low toxicity and environmental protection;

(3) According to the method for decrosslinking the rubber, the micromolecule alcohol solution with a certain PH value is used as the hydrolysate, toxic organic reagents such as tetrahydrofuran, acetone and the like are not needed, the decrosslinking method is low in toxicity and more environment-friendly, and the same hydrolysis effect can be achieved;

(4) According to the method for decrosslinking the rubber, rubber molecules only swell and do not dissolve in the alcohol solution, compared with organic reagents such as tetrahydrofuran, acetone and the like, the hydrolyzed rubber does not need to be flocculated by using solvents such as ethanol and the like, and the rubber is simpler and more convenient to recover.

(5) The vulcanized rubber decrosslinking method can realize the closed-loop recovery of vulcanized rubber, namely the closed-loop process from the crude rubber to the vulcanized rubber to the crude rubber, on one hand, the recovered crude rubber is basically the same as that before treatment, the subsequent reprocessing method of the recovered rubber is more elastic, and on the other hand, the closed-loop recovery ensures that the recyclable environment-friendly rubber sole material is very environment-friendly.

Drawings

FIG. 1 is an infrared spectrum of the carboxylated nitrile rubber used in example 1 and of the hydrolyzed recycled rubber;

FIG. 2 shows the nuclear magnetic spectra of the carboxylated nitrile rubber used in example 1 and of the hydrolyzed recycled rubber.

Detailed Description

While the present invention will be described in detail and with reference to the specific embodiments thereof, it should be understood that the following detailed description is merely illustrative of the present invention and should not be taken as limiting the scope of the present invention, but is intended to cover modifications and variations thereof that would occur to those skilled in the art upon reading the present disclosure.

The maleic anhydride graft modified rubber and the mercapto acid graft modified rubber used in the examples were synthesized in a laboratory; the other raw materials used in the examples and comparative examples are all commercially available;

the main raw materials are as follows:

acrylonitrile-butadiene-methacrylic acid copolymer gum (carboxylated nitrile gum, XNBR): german Langsheng company;

styrene-butadiene-methacrylic acid copolymer gum (carboxylated styrene-butadiene gum, XSBR): shanghai Gaoqiaobascu;

preparation of maleic anhydride graft modified rubber:

adjusting the temperature of a Haake internal mixer to 170 ℃, adding 100g of rubber to be modified, and completely melting; then adding certain maleic anhydride and initiator BPO, carrying out melt grafting for 10min to obtain maleic anhydride grafted rubber, placing the graft in a Soxhlet extractor, adding 70ml of acetone, carrying out reflux extraction at 85 ℃ for 24h, and fully swelling the graft so as to remove unreacted maleic anhydride monomer and possible maleic anhydride copolymer. Then, the mixture was dried in a vacuum oven at 70 ℃ for 12 hours to obtain a purified maleic anhydride graft-modified rubber.

Preparation of mercaptan acid graft modified rubber:

weighing 50g of rubber to be modified, dissolving the rubber in 1L of tetrahydrofuran, adding a certain amount of 3-mercaptopropionic acid, fully dissolving, adding a certain amount of photoinitiator benzoin dimethyl ether (DMPA), placing the mixture under an ultraviolet lamp under the protection of nitrogen atmosphere, and obtaining mercaptoacid modified rubber with different grafting rates by changing the illumination time, wherein the illumination is used for 9min in example 6; and then pouring the solution into a beaker filled with deionized water for flocculation, adding the flocculent gel into tetrahydrofuran, and repeating the steps for four times to obtain the pure grafted 3-mercaptopropionic acid grafted modified rubber.

The test method comprises the following steps:

1. and (3) testing tension: the experiment test machine is used for CMT4104 universal materials of Shenzhen Sansi (SANS). Preparing a sample strip in a rubber standard tensile test, and processing a test method and a test result according to the GB/T528-2009 test standard requirement;

2. and (3) infrared testing: the wave number was set to 400cm using a Tensor 27 type infrared spectrometer from Bruker, germany ^-1 To 4000cm ^-1 Firstly, dissolving a sample to be tested in THF, dripping a sample solution on a KBr sheet which is pressed in advance after the sample is completely dissolved, and drying the sample solution by an infrared oven for testing;

3. nuclear magnetic testing: 1H-NMR characterization was carried out using 400MHz NMR, AV400, from Bruker. Using deuterated chloroform (CDCl 3) as a solvent, weighing about 10-15 mg of sample, and dissolving the sample in the CDCl3 for testing;

GPC measurement: molecular weight testing was performed using model number Waters 1525 GPC from Waters corporation, USA. The sample preparation method comprises the following steps: THF is adopted as a solvent, 100mg of sample is dissolved in THF, and the concentration of the sample is 5mg/mL;

5. and (3) testing the vulcanization characteristic: the rubber vulcanization characteristic is characterized by using an MR.C 3 type rotor-free vulcanizing instrument of Beijing Ruidayuchen instrument, inc.;

6. compression set test: preparing a sample with compression set, and processing a test method and a test result according to the requirements of GB/T7759.1-2015 test standard;

7. mooney viscosity test: GB/T1232.1-2016 test method.

Example 1

(1) Rubber mixing: weighing 100 parts by weight of acrylonitrile-butadiene-methacrylic acid copolymer rubber (carboxylated nitrile rubber, XNBR) (the content of methacrylic acid is 7 percent), adjusting the roll spacing of an open mill to be 0.5mm, keeping the roll temperature at 50 ℃, and controlling the rotation speed ratio of the front roller to the rear roller to be 1.5, wherein the rubber is prepared by mixing the following components in parts by weight

Plasticating for three times by using a double-roller open mill, adjusting the temperature of an internal mixer to be 80 ℃, and the rotating speed to be 60r/min, and then adding rubber materials into the internal mixer for mixing for 2min; then 2 parts by weight of anti-aging agent 4020 is added into the internal mixer, and the mixture is mixed for 2min; then adding 5 parts by weight of plasticizer coumarone resin, and mixing for 1min; and finally, adding 40 parts by weight of reinforcing agent/filler N330 carbon black, mixing for 7min, removing the mixed rubber from an internal mixer, and cooling to room temperature. Adjusting the roll spacing of the open mill to be 0.8mm, wrapping rubber rolls, adding 3 parts by weight of tetraglycidyl xylene diamine (TGXDA) cross-linking agent, cutting for 4 times, alternately beating 12 triangular bags and 6 rolls to uniformly disperse small materials, and then discharging sheets.

(2) And (3) vulcanization: setting the vulcanization temperature to 180 ℃ and the vulcanization time to 9min, pressing the mixture into a square vulcanized rubber sample with the thickness of 1mm, and pressing the square vulcanized rubber sample into a cylindrical sample with the diameter of 3mm and the height of 1.5mm by using the vulcanization time of the sample of 1.5 times, thereby obtaining the sample of the recyclable environment-friendly rubber sole material.

(3) The de-crosslinking recovery of the recyclable environment-friendly rubber sole material: taking 25g of the sample piece of the recycled environment-friendly rubber sole material prepared in the step (2), crushing the sample piece into waste rubber particles with the particle size of 0.2mm, and preparing a mixed solution of ethanol and water, wherein the ethanol: and (2) dissolving sodium hydroxide in the mixed solution according to the volume ratio of water being 4. Adding the waste rubber powder into the hydrolysate, stirring at 70 ℃, and condensing and refluxing for 12h. And acidifying the recovered glue, washing with a large amount of deionized water, and drying to constant weight.

(4) Reprocessing of the recovered glue: adding the cross-linking agent and other ingredients again by the methods in (1) and (2) to obtain a sole sample piece, and testing the performance of the sole sample piece to be compared with the recyclable environment-friendly rubber sole material.

Example 2

The difference from the embodiment 1 is that: the vulcanization temperature is 150 ℃, and the vulcanization time is 33min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 3

The difference from the embodiment 1 is that:

the cross-linking agent is triglycidyl-p-aminophenol (TPAP), and the using amount is 5 parts by weight;

the vulcanization temperature is 170 ℃, and the vulcanization time is 20min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 4

The difference from the embodiment 1 is that:

the cross-linking agent is tetraglycidyl-1, 3-bisaminomethylcyclohexane (TGBAMCH) and is used in 4 weight portions;

the vulcanization temperature is 160 ℃, and the vulcanization time is 20min;

the reinforcing agent is N330 carbon black, and the using amount is 20 parts by weight;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 5

The difference from the embodiment 1 is that:

the amount of coumarone resin is 25 parts by weight;

the vulcanization temperature is 180 ℃, and the vulcanization time is 14min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 6

The difference from the embodiment 1 is that:

the cross-linking agent is triglycidyl isocyanurate (TGIC) and is used in 1 weight part;

setting the vulcanization temperature at 180 ℃ and the vulcanization time at 10min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 7

The difference from the embodiment 1 is that:

the anti-aging agent is a mixture of anti-aging agent BLE and anti-aging agent RD, wherein the weight parts of the anti-aging agent BLE and the anti-aging agent RD are respectively 0.15, and the total weight is 0.3;

the reinforcing agent is a mixture of white carbon black and calcium carbonate, wherein the white carbon black accounts for 20 parts by weight, the calcium carbonate accounts for 40 parts by weight, and the total amount accounts for 60 parts by weight;

the vulcanization temperature is 180 ℃, and the vulcanization time is 19min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 8

The difference from the embodiment 1 is that:

the anti-aging agent is a mixture of the anti-aging agent 2246 and the anti-aging agent H, wherein the weight parts of the anti-aging agent and the anti-aging agent H are respectively 1.5, and the total weight is 3;

the reinforcing agent is a mixture of calcium carbonate, talcum powder and kaolin, and the mass of the reinforcing agent, the talcum powder and the kaolin is respectively 30 parts by weight, 5 parts by weight and 5 parts by weight, and the total weight is 40 parts by weight;

the vulcanization temperature is 180 ℃, and the vulcanization time is 12min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 9

The difference from the embodiment 1 is that:

the carboxyl functional rubber is styrene-butadiene-methacrylic acid copolymer rubber (carboxyl styrene-butadiene rubber, XSBR) (the content of methacrylic acid is 7%);

the vulcanization temperature is 190 ℃, and the vulcanization time is 22min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 10

The difference from the embodiment 1 is that:

the carboxyl functionalized rubber is ethylene propylene diene monomer grafted by maleic anhydride (the grafting rate of the maleic anhydride is 5 percent);

the cross-linking agent is triglycidyl isocyanurate (TGIC) and is used in 4 weight parts;

the vulcanization temperature is 180 ℃, and the vulcanization time is 18min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 11

The difference from the embodiment 1 is that:

the carboxyl functionalized rubber is styrene butadiene rubber grafted by maleic anhydride (the grafting rate of the maleic anhydride is 35 percent);

the cross-linking agent is selected from triglycidyl isocyanurate (TGIC) and is used in 8 parts by weight;

setting the vulcanization temperature at 180 ℃ and the vulcanization time at 13min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 12

The difference from the embodiment 1 is that:

the carboxyl functional rubber is butadiene rubber grafted by mercaptopropionic acid (grafting rate: 5%);

the cross-linking agent is tetraglycidyl xylene diamine (TGXDA) and the dosage is 2 weight portions;

setting the vulcanization temperature at 180 ℃ and the vulcanization time at 15min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 13

The difference from the embodiment 1 is that:

the carboxyl functional rubber is mercaptoacetic acid grafted styrene-butadiene rubber (grafting rate: 35%);

the cross-linking agent is selected from tetraglycidyl xylene diamine (TGXDA) and is used in 10 weight portions;

setting the vulcanization temperature at 180 ℃ and the vulcanization time at 18min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 14

Hydrolyzing and recycling the recyclable environment-friendly rubber sole material prepared in the example 1;

the difference from the embodiment 1 is that:

in the hydrolysis step, replacing sodium hydroxide with hydroiodic acid (HI) with the preparation concentration of 2mol/L, setting the hydrolysis temperature to be 80 ℃ and the hydrolysis time to be 18h; acidification is not needed after hydrolysis;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 15

Hydrolyzing and recycling the recyclable environment-friendly rubber sole material prepared in the example 1;

the difference from the embodiment 1 is that:

in the hydrolysis step, replacing sodium hydroxide with triethylamine, replacing ethanol with isopropanol, wherein the volume ratio of isopropanol to water is 7;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 16

Hydrolyzing and recycling the recyclable environment-friendly rubber sole material prepared in the example 1;

the difference from the embodiment 1 is that:

in the hydrolysis step, replacing sodium hydroxide with hydrochloric acid, wherein the concentration is 0.5mol/L, the volume ratio of ethanol to water is 7; acidification is not needed after hydrolysis;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Example 17

Hydrolyzing and recycling the recyclable environment-friendly rubber sole material prepared in example 10;

the difference from the embodiment 10 is that:

in the hydrolysis step, replacing sodium hydroxide with hydrochloric acid, wherein the concentration is 1mol/L, the volume ratio of ethanol to water is 6; acidification is not needed after hydrolysis;

the remaining formulation, processing conditions and recovery conditions were the same as in example 10.

Example 18

Hydrolysis recovery was performed using the recyclable environment-friendly rubber sole material prepared in example 11;

the difference from example 11 is:

in the hydrolysis step, the concentration of sodium hydroxide is 0.5mol/L, the volume ratio of ethanol to water is 5;

the remaining formulation, processing conditions and recovery conditions were the same as in example 11.

Example 19

Hydrolyzing and recycling the recyclable environment-friendly rubber sole material prepared in the example 1;

the difference from the embodiment 1 is that: replacing sodium hydroxide with hydrochloric acid, replacing ethanol with isopropanol, wherein the volume ratio of isopropanol to water is 10; acidification is not needed after hydrolysis;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Comparative example 1

The difference from the embodiment 1 is that:

the cross-linking agent is Epoxidized Soybean Oil (ESO) without a tertiary amine structure, and the dosage is 10 parts by weight;

the vulcanization temperature is 180 ℃, and the vulcanization time is 48min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Comparative example 2

Hydrolyzing and recycling the recyclable environment-friendly rubber sole material prepared in the example 1;

the difference from the embodiment 1 is that:

in the hydrolysis step, replacing the hydrolysate with Tetrahydrofuran (THF) aqueous solution, wherein the THF is prepared from the THF with commercially available AR purity and deionized water, and the volume ratio of the THF to the deionized water is 4;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Comparative example 3

The difference from the embodiment 1 is that:

the cross-linking agent is epoxy resin bisphenol A diglycidyl ether (BADGE) without tertiary amine structure, and the using amount is 5 parts by weight;

the vulcanization temperature is 180 ℃, and the vulcanization time is 37min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Comparative example 4

A conventional sulfur vulcanization system is employed.

The difference from example 1 is:

the crosslinker was replaced by: 1 part by weight of sulfur, 1 part by weight of stearic acid, 3 parts by weight of zinc oxide and 1 part by weight of promoter CZ;

the vulcanization systems are all added into an open mill, the vulcanization temperature is set to be 150 ℃, and the vulcanization time is 28min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Comparative example 4 was designed according to an industrial sulfur curing formulation, where the optimum curing temperature for an industrial sulfur curing formulation was typically 150 ℃ and comparative example 4 was designed primarily to compare the hydrolytic properties of conventional curing systems.

Comparative example 5

A peroxide cure system is employed.

The difference from the embodiment 1 is that:

replacing the cross-linking agent by DCP with 3 weight portions;

adding a vulcanizing agent into an open mill, setting the vulcanizing temperature at 170 ℃ and the vulcanizing time at 9min;

the remaining formulation, processing conditions and recovery conditions were the same as in example 1.

Comparative example 5 was designed according to a commercial DCP cure recipe, which typically uses 170 c, and comparative example 5 is primarily to compare the hydrolytic properties of DCP cure systems.

Table 1 shows a comparison of GPC data of the original carboxylated nitrile rubber and the hydrolyzed recycled rubber in example 1, and the test results show that the molecular weight of the original carboxylated nitrile rubber and the molecular weight of the recycled rubber are not changed greatly, the molecular weight distribution is also changed slightly, and the main chain of the rubber molecule is not damaged in the recycling process.

TABLE 1 comparison of GPC data for recovered gums and virgin gums in example 1

Kind of rubber	Mn(×10 4 )	Mw(×10 4 )	PDI
				Ortho-carboxy butyronitrile rubber	8.6	27.0	3.16
Recovery glue	7.0	23.1	3.29

As can be seen from FIG. 1, the IR spectra of the carboxylated nitrile rubber used in example 1 and the hydrolyzed reclaimed rubber are almost completely consistent, which indicates that the hydrolysis method does not damage the inherent functional groups of the rubber molecular chain; as can be seen from FIG. 2, the nuclear magnetic spectra of the carboxylated nitrile rubber used in example 1 and the reclaimed rubber after hydrolysis are almost completely consistent, which indicates that the content of the inherent functional groups of the rubber molecular chains is not changed before and after hydrolysis; the results of the infrared test and the nuclear magnetic test fully prove the effect of the hydrolysis method of the invention, and the repeated processing performance is considerable.

TABLE 2 mechanical and vulcanization Properties of examples 1 to 19 and comparative examples 1 to 5

TABLE 3 comparison of the recovery Performance data for examples 1-19 and comparative examples 1-5

The vulcanization time of examples 1 to 19 and comparative examples 1 to 5 in table 2 is measured by a vulcanization instrument, the vulcanization temperature and the vulcanization time are mainly used for measuring the vulcanization rate, the lower the temperature is, the shorter the time is, the faster the vulcanization rate is, and the higher the mechanical strength can be kept under the condition of maintaining the faster vulcanization rate is also an important factor for measuring vulcanization; the compression set is an important measure of the quality of the sole, and the smaller the compression set, the better the quality of the sole material.

The properties of the reclaimed rubber of examples 1 to 19 and comparative examples 1 to 5 are shown in Table 3. Mooney viscosity is an important measure of the degree of hydrolysis, and the lower the Mooney viscosity, the more hydrolytically broken crosslinks, the better the hydrolysis and the closer the recovered product is to the original product. The re-crosslinking after hydrolysis has better mechanical properties, which indicates that the hydrolysis effect is better.

The mechanical property of the rubber material after alkaline hydrolysis is improved to a certain extent because metal cations in the hydrolysate can form ionic bonds with carboxyl, so that the function of sacrificing bonds is achieved, and the mechanical property of the material is enhanced to a certain extent.

Comparative examples 1 and 3 used epoxidized soybean oil ESO and epoxy bisphenol A diglycidyl ether (BADGE) crosslinker, respectively;

compared with example 1, the epoxy value of the epoxidized soybean oil ESO crosslinking agent used in comparative example 1 is different (TGXDA epoxy value is 0.85, ESO epoxy value is 6.5), and the relative molecular mass of ESO is much larger than that of TGXDA, so that the amount of ESO is larger than that of TGXDA in order to ensure comparison at approximately the same crosslinking density; when the amount of ESO is larger, the vulcanization rate is still smaller than that of TGXDA, which shows that the vulcanization rate of TGXDA is fast and the vulcanization efficiency is high, and meanwhile, under the condition of equal crosslinking density, the mechanical property of TGXDA is stronger than that of ESO, the recovery condition is better than that of ESO, and the superiority of TGXDA as a crosslinking agent can be better described.

The epoxy resins used in comparative example 3 were similar to those of example 1 in epoxy value (TGXDA epoxy value of 0.85 and BADGE epoxy value of 0.90) for bisphenol a diglycidyl ether (BADGE) cross-linker, but only two epoxy groups per BADGE molecule, so that BADGE was used in greater amounts than TGXDA to ensure comparison at approximately the same cross-link density; when the BADGE is used in a large amount, the vulcanization rate is still lower than that of TGXDA, which shows that the vulcanization rate of TGXDA is high, the vulcanization efficiency is high, and meanwhile, under the condition of equal crosslinking density, the mechanical property of TGXDA is stronger than that of BADGE, and the recovery condition is better than that of BADGE, and the superiority of TGXDA as a crosslinking agent is also proved.

Comparative example 2 using Tetrahydrofuran (THF) aqueous solution as hydrolysis solution, THF and rubber have good swelling effect, hydrolysis effect should be better, but THF is a toxic solvent, the alcohol solvent used in the invention is non-toxic, and as hydrolysis solution can achieve hydrolysis effect equivalent to THF, which means that it is a good environmental protection hydrolysis method to replace THF and other toxic reagents.

Comparative example 4 and comparative example 5 use sulphur and DCP as cross-linking agent respectively, can't carry on the closed loop to reclaim through this kind of chemical recovery method, also further prove, the sole sample piece that such formulation designs out is superior to the traditional vulcanization system, can reduce more waste rubber pollution, realize high-value recovery and reuse of material.

The data for examples 1-19 and comparative examples 1-5 demonstrate that: the vulcanization system is a green crosslinking system, is nontoxic and pollution-free, and can realize chemical closed-loop recovery under mild conditions; the polyfunctional glycidol amine crosslinking agent adopted by the invention has high reaction rate and high reaction efficiency, and the crosslinked product has good hydrolysis performance; the method utilizes the aqueous solution of alcohol as a reaction medium, is very environment-friendly, has good hydrolysis effect, and has the hydrolysis effect equivalent to that of THF organic solvents.

Claims (10)

1. A recyclable environment-friendly rubber sole material is characterized in that:

the recyclable environment-friendly rubber sole material is prepared from raw materials including carboxyl functionalized rubber, a cross-linking agent, an anti-aging agent and a reinforcing agent; preferably, the raw materials also comprise a plasticizer;

based on 100 parts by weight of the carboxyl-functional rubber,

2. the recyclable environment-friendly rubber sole material as set forth in claim 1, wherein:

based on 100 parts by weight of the carboxyl-functional rubber,

3. the recyclable environmentally friendly rubber sole material of claim 1, wherein:

the carboxyl functional rubber is at least one of copolymer rubber, maleic anhydride graft modified rubber and carboxyl graft modified rubber containing carboxyl functional group monomers;

the copolymer adhesive containing carboxyl functional groups is at least one of acrylonitrile-butadiene-methacrylic acid copolymer adhesive, acrylonitrile-butadiene-acrylic acid copolymer adhesive, styrene-butadiene-methacrylic acid copolymer adhesive, styrene-butadiene-acrylic acid copolymer adhesive, isoprene-methacrylic acid copolymer adhesive, isoprene-acrylic acid copolymer adhesive, butadiene-methacrylic acid copolymer adhesive, butadiene-acrylic acid copolymer adhesive, butadiene-isobutylene-methacrylic acid copolymer adhesive, butadiene-isobutylene-acrylic acid copolymer adhesive, ethylene-propylene-methacrylic acid copolymer adhesive and ethylene-propylene-acrylic acid copolymer adhesive; wherein the mass of the monomer containing the carboxyl functional group accounts for 0.1-40 percent of the total mass of the copolymer rubber, and preferably 3-10 percent;

the maleic acid grafted modified rubber is at least one of maleic anhydride grafted modified nitrile rubber, maleic anhydride grafted modified styrene-butadiene rubber, maleic anhydride grafted modified natural rubber, maleic anhydride grafted modified ethylene propylene diene monomer rubber, maleic anhydride grafted modified butyl rubber and hydrolysis products of the maleic anhydride grafted modified butyl rubber and the maleic anhydride grafted modified butyl rubber; wherein the grafting rate of the maleic anhydride is 0.1-40%, preferably 3-35%;

the carboxyl grafted modified rubber is at least one of thioglycollic acid grafted styrene butadiene rubber, mercaptopropionic acid grafted styrene butadiene rubber, thioglycollic acid grafted butadiene rubber and mercaptopropionic acid grafted butadiene rubber; wherein the grafting ratio of the mercapto acid is 0.5-50%, preferably 2-35%.

4. The recyclable environment-friendly rubber sole material as set forth in claim 1, wherein:

the cross-linking agent is glycidyl amine epoxy resin, preferably at least one of triglycidyl-p-aminophenol, triglycidyl isocyanurate, tetraglycidyl xylene diamine and tetraglycidyl-1, 3-bisaminomethylcyclohexane.

5. The recyclable environment-friendly rubber sole material as set forth in claim 1, wherein:

the anti-aging agent is at least one of 6-ethoxy-2, 4-trimethyl-1, 2-dihydroquinoline, N-phenyl-2-naphthylamine, N '-diphenyl-p-phenylenediamine, N- (1, 3-dimethyl) butyl-N' -phenyl-p-phenylenediamine, N-isopropyl-N '-phenyl-p-phenylenediamine, 9-dimethylacridine, 2, 4-trimethyl-1, 2-dihydroquinoline polymer and 2,2' -methylene bis (4-methyl-6-tert-butylphenol); and/or the presence of a gas in the gas,

the reinforcing agent is at least one of carbon black, calcium carbonate, white carbon black, talcum powder, kaolin and titanium dioxide; and/or the presence of a gas in the gas,

the plasticizer is at least one of operation oil, paraffin, coal tar, coumarone resin and polyester plasticizer.

6. A method for preparing the recyclable environment-friendly rubber sole material as described in any one of claims 1 to 5, comprising:

plasticating the carboxyl functionalized rubber, adding an anti-aging agent, a reinforcing agent and a crosslinking agent, adding or not adding a plasticizer, uniformly mixing and vulcanizing to obtain the recyclable environment-friendly rubber sole material.

7. The method for preparing the recyclable environment-friendly rubber sole material as described in claim 6, wherein the method comprises the following steps:

the vulcanization temperature is 150-220 ℃, and preferably 150-190 ℃;

the vulcanization time is 5min to 60min, preferably 10min to 35min.

8. A recycling method of the recyclable eco-rubber shoe sole material according to any one of claims 1 to 5 or the recyclable eco-rubber shoe sole material prepared by the method according to any one of claims 6 to 7, wherein the method comprises:

crushing the recyclable environment-friendly rubber sole material, hydrolyzing with a hydrolysis solution, washing and drying a hydrolyzed product.

9. The recycling method of recyclable environment-friendly rubber shoe sole material as set forth in claim 8, wherein:

the recyclable environment-friendly rubber sole material is crushed into particles with the particle size of 0.1-5 mm, preferably 0.1-2 mm;

the hydrolysate is prepared by mixing alkali or acid, water and alcohol;

the volume ratio of water to alcohol is 1;

the acid-base concentration of the hydrolysate is 0.1-5 mol/L, preferably 0.5-2mol/L;

the hydrolysis temperature is 50-90 ℃, preferably 60-80 ℃;

the hydrolysis time is 6 to 18 hours, preferably 9 to 18 hours.

10. The recycling method of recyclable environment-friendly rubber shoe sole material as set forth in claim 8, wherein:

the alcohol is at least one of methanol, ethanol, butanol and isopropanol; and/or the presence of a gas in the gas,

the alkali is at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, trimethylamine, triethylamine, dimethylamine, diethylamine, sodium alkoxide and potassium alkoxide; and/or the presence of a gas in the gas,

the acid is at least one of hydrogen chloride, hydrogen bromide, hydrogen iodide and sulfuric acid.

Images