1. A modified nitrile rubber composition is characterized by comprising the following components which are stored in a mixed manner or independently:

nitrile butadiene rubber matrix, lignin, a main modifier, an auxiliary modifier, a vulcanizing agent, a vulcanization accelerator and an activation auxiliary agent,

the main modifier is at least one of mercapto triazole compounds, and the auxiliary modifier is ZnCl₂、CuCl₂、FeCl₃、FeCl₂、NiCl₂、CaCl₂At least one of zinc acrylate, zinc methacrylate and zinc sorbate;

relative to 100 parts by weight of a nitrile rubber matrix, the lignin content is 3-100 parts by weight, the main modifier content is 0.5-12 parts by weight, the auxiliary modifier content is 0.5-10 parts by weight, the vulcanizing agent content is 0.1-10 parts by weight, the vulcanization accelerator content is 1-5 parts by weight, and the activating auxiliary agent content is 1-20 parts by weight.

2. The composition according to claim 1, wherein the lignin is contained in an amount of 10-100 parts by weight, the primary modifier is contained in an amount of 1-10 parts by weight, the secondary modifier is contained in an amount of 1-8 parts by weight, the vulcanizing agent is contained in an amount of 2-8 parts by weight, the vulcanization accelerator is contained in an amount of 1-3 parts by weight, and the activating assistant is contained in an amount of 2-15 parts by weight, relative to 100 parts by weight of a nitrile rubber matrix.

3. The composition of claim 1 or 2, wherein the main modifier is at least one selected from 3-mercapto-1, 2, 4-triazole, 3-amino-5-mercapto-1, 2, 4-triazole, 4-amino-3-mercapto-4H-1, 2, 4-triazole, 5-aminomethyl-2-mercapto-4H-1, 2, 4-triazole, 5- (2-pyridine) -3-mercapto-1, 2, 4-triazole, and 5- (4-pyridine) -1H-3-mercapto 1,2, 4-triazole;

preferably, the main modifier is 3-mercapto-1, 2, 4-triazole and/or 5- (2-pyridine) -3-mercapto-1, 2, 4-triazole.

4. The composition according to any one of claims 1-3, wherein the vulcanizing agent is selected from at least one of sulfur donors; preferably, the sulfur is selected from at least one of insoluble sulfur, soluble sulfur and oil-extended sulfur;

preferably, the vulcanization accelerator is selected from at least one of sulfenamide accelerators, thiazole accelerators, thiuram accelerators and guanidine accelerators; preferably, the vulcanization accelerator is tetramethylthiuram disulfide and/or N-cyclohexyl-2-benzothiazolesulfenamide.

5. The composition according to any one of claims 1 to 4, wherein the nitrile rubber matrix has a content of acrylonitrile structural units of 20 to 50% by weight, a content of 1, 2-butadiene structural units of 5 to 15% by weight, a Mooney viscosity of 35 to 90;

preferably, the content of phenolic hydroxyl in the lignin is more than or equal to 3.0 weight percent, and the number average molecular weight is 2500-5500;

preferably, the lignin is at least one selected from alkali lignin obtained by alkali pulping in paper industry, enzymatic lignin extracted from ethanol produced by fermentation of lignocellulose and organic solvent lignin extracted from lignocellulose by organic solvent method.

6. The composition of any of claims 1-5, wherein the activation aid is a mixture of a metal oxide and a fatty acid;

preferably, the metal oxide is zinc oxide and/or magnesium oxide;

preferably, the fatty acid is stearic acid.

7. A method for preparing a mercapto triazole modified nitrile rubber composite material, which is characterized by comprising the steps of mixing the components in the composition as claimed in any one of claims 1 to 6, and vulcanizing the mixed discharge rubber.

8. The method of claim 7, wherein mixing the components of the composition and curing the compounded gum comprises:

(1) carrying out first mixing on a nitrile rubber matrix and a main modifier to obtain a first mixed material;

(2) carrying out second mixing on the first mixed material, lignin, an auxiliary modifier or an activating auxiliary agent to obtain a second mixed material;

(3) performing third mixing on the second mixed material, a vulcanizing agent and a vulcanization accelerator, and then discharging to obtain a discharged rubber;

(4) and vulcanizing the discharged rubber.

9. The method of claim 8, wherein in step (1), the conditions of the first mixing comprise: the temperature is 100-;

preferably, the first mixing is carried out in an internal mixer at a speed of 50 to 90rpm, preferably 60 to 90 rpm.

10. The method of claim 8 or 9, wherein in step (2), the conditions of the second mixing comprise: the temperature is 100-160 ℃, and the time is 3-15 min;

preferably, the conditions of the third mixing include: the temperature is not more than 130 ℃, and the time is 5-7 min;

preferably, the conditions of the vulcanization include: the temperature is 150 ℃ and 170 ℃, the pressure is 10-20MPa, and the time is 25-40 min.

11. The mercapto triazole modified nitrile rubber composite material prepared by the method of any one of claims 7-10.

12. The use of the mercaptotriazole modified nitrile rubber composite material of claim 11 in at least one selected from the group consisting of automotive hoses, printer rollers, sealing materials and foamed thermal insulation materials.

Background

Nitrile-butadiene rubber (NBR) is a synthetic rubber prepared by copolymerizing butadiene and acrylonitrile emulsion, and is widely applied to the fields of automobiles, aerospace, petrochemical industry, textiles, wires and cables, printing, food packaging and the like by virtue of good oil resistance, hydrocarbon solvent resistance and thermal aging resistance. Its disadvantages are poor low-temp resistance, ozone resistance and poor anti-ultraviolet ageing performance.

Aiming at the defects of heat-oxygen aging resistance and ultraviolet resistance, a common solution is to add small-molecule antioxidants and light stabilizers such as hindered phenols, hindered amines and the like, but the problems of migration, extraction, certain toxicity, environmental pollution and the like exist.

The lignin is a renewable aromatic polymer with the greatest abundance in the nature, and the main sources are byproducts of the pulping and papermaking industry and lignin generated by biomass (wood/straw and the like) hydrolysis.

Phenolic hydroxyl, carbonyl, ether bond, methoxyl, aldehyde group, carboxyl and the like in the molecular structure of the lignin endow the lignin with higher reaction activity, and the characteristic structures of benzene ring, phenolic hydroxyl and the like enable the lignin to have excellent ultraviolet radiation resistance and ageing resistance. The lignin is used for replacing carbon black to prepare the rubber/lignin composite material with excellent ultraviolet resistance and aging resistance, so that the cost of the rubber material can be reduced, and the method has important significance for promoting the effective utilization of biomass resources and the green development of high polymer materials.

Although the ageing resistance and the ultraviolet light resistance of lignin can be utilized, lignin molecules are easy to agglomerate, so that the lignin molecules are poor in compatibility with a rubber matrix and difficult to disperse, and even polar rubbers such as nitrile rubber cannot ensure good dispersion and interface combination.

The method comprises the steps of pretreating enzymatic hydrolysis lignin by adopting a physical method, and then mixing the treated lignin and raw rubber by using a dry mixing process, wherein the tensile strength and the tearing strength of a final composite material are improved compared with those of a pure rubber system, but the elongation at break is not greatly increased or even reduced. In addition, the steps of physical treatment of lignin are complicated, the cost is high, and the industrial production and the application and popularization are not facilitated. CN107383475A discloses a lignin/nitrile rubber composite material and a preparation method thereof, wherein an energy sacrifice bond effect of covalent bond connection is constructed between the interface of lignin and nitrile rubber through the action of a reactive compatilizer and a modifier, the interface compatibility of the lignin and a rubber matrix is improved, and the prepared lignin/nitrile rubber composite material has excellent comprehensive mechanical properties. However, the compatilizer which must be introduced can sacrifice the performance of the nitrile rubber matrix part, and the compatilizer and the modifier have more relevant influence factors on the reaction based on the complexity of a composition system.

Therefore, how to further improve the interface compatibility of lignin and a rubber matrix by a simple and direct method and realize the increase of the strength and toughness of a modified nitrile-butadiene rubber system is a major difficulty which needs to be solved urgently by current research.

Disclosure of Invention

The invention aims to overcome the defects that lignin is poorly dispersed in a rubber matrix, the interface bonding between rubber and lignin is poor, and the strength and toughness of the obtained vulcanized rubber cannot be improved simultaneously in the prior art.

In order to achieve the above object, a first aspect of the present invention provides a modified nitrile rubber composition comprising the following components stored in admixture or separately:

nitrile butadiene rubber matrix, lignin, a main modifier, an auxiliary modifier, a vulcanizing agent, a vulcanization accelerator and an activation auxiliary agent,

the main modifier is at least one of mercapto triazole compounds, and the auxiliary modifier is ZnCl₂、CuCl₂、FeCl₃、FeCl₂、NiCl₂、CaCl₂At least one of zinc acrylate, zinc methacrylate and zinc sorbate;

relative to 100 parts by weight of a nitrile rubber matrix, the lignin content is 3-100 parts by weight, the main modifier content is 0.5-12 parts by weight, the auxiliary modifier content is 0.5-10 parts by weight, the vulcanizing agent content is 0.1-10 parts by weight, the vulcanization accelerator content is 1-5 parts by weight, and the activating auxiliary agent content is 1-20 parts by weight.

The second aspect of the invention provides a method for preparing a mercapto triazole modified nitrile rubber composite material, which comprises the steps of mixing the components in the composition in the first aspect, and vulcanizing the mixed discharge rubber.

The third aspect of the invention provides the mercapto triazole modified nitrile rubber composite material prepared by the method.

The fourth aspect of the invention provides an application of the mercapto triazole modified nitrile rubber composite material in at least one selected from automobile hoses, printer rollers, sealing materials and foamed heat insulation materials.

According to the invention, through the action of the main modifier, the auxiliary modifier and other components, a triazole structure is introduced into a nitrile rubber molecular chain, an energy sacrificial bond effect (metal coordination effect and hydrogen bond effect) is established between the interface of filler lignin and nitrile rubber, and the comprehensive mechanical property of the prepared modified nitrile rubber composite material is greatly improved; the dispersion size of the filler lignin is also reduced, and the problem of insufficient interface bonding of the lignin and the nitrile rubber is better solved.

The nitrile rubber composite material with different mechanical properties can be obtained by adjusting the using amount of each component in the modified nitrile rubber composition, the tensile strength can reach 20-30MPa, and the elongation at break can reach 300-.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In the case of no specific description, the Mooney viscosities described in the present invention are all measured by preheating a large rotor for 1min using a Mooney viscometer at 100 ℃ and rotating for 4 min.

As described above, the first aspect of the present invention provides a modified nitrile rubber composition comprising the following components stored in admixture or separately:

nitrile butadiene rubber matrix, lignin, a main modifier, an auxiliary modifier, a vulcanizing agent, a vulcanization accelerator and an activation auxiliary agent,

the main modifier is at least one of mercapto triazole compounds, and the auxiliary modifier is ZnCl₂、CuCl₂、FeCl₃、FeCl₂、NiCl₂、CaCl₂At least one of zinc acrylate, zinc methacrylate and zinc sorbate;

relative to 100 parts by weight of a nitrile rubber matrix, the lignin content is 3-100 parts by weight, the main modifier content is 0.5-12 parts by weight, the auxiliary modifier content is 0.5-10 parts by weight, the vulcanizing agent content is 0.1-10 parts by weight, the vulcanization accelerator content is 1-5 parts by weight, and the activating auxiliary agent content is 1-20 parts by weight.

More preferably, in order to obtain better strength and toughness of the obtained rubber material, relative to 100 parts by weight of the nitrile rubber matrix, the lignin content is 10-100 parts by weight, the main modifier content is 1-10 parts by weight, the auxiliary modifier content is 1-8 parts by weight, the vulcanizing agent content is 2-8 parts by weight, the vulcanization accelerator content is 1-3 parts by weight, and the activating auxiliary agent content is 2-15 parts by weight.

Preferably, the main modifier is at least one selected from 3-mercapto-1, 2, 4-triazole, 3-amino-5-mercapto-1, 2, 4-triazole, 4-amino-3-mercapto-4H-1, 2, 4-triazole, 5-aminomethyl-2-mercapto-4H-1, 2, 4-triazole, 5- (2-pyridine) -3-mercapto-1, 2, 4-triazole and 5- (4-pyridine) -1H-3-mercapto 1,2, 4-triazole.

In order to further improve the strength and toughness of the vulcanized rubber obtained from the composition, the main modifier is more preferably 3-mercapto-1, 2, 4-triazole and/or 5- (2-pyridine) -3-mercapto-1, 2, 4-triazole.

Preferably, the vulcanizing agent is selected from at least one of sulfur donors. Preferably, the sulfur donor refers to a substance capable of providing sulfur. The sulfur comprises at least one of insoluble sulfur, soluble sulfur and oil-extended sulfur. For example, the vulcanizing agent IS ordinary sulfur S, oil-extended insoluble sulfur IS, or the like.

Preferably, the vulcanization accelerator is selected from at least one of sulfenamide accelerators, thiazole accelerators, thiuram accelerators and guanidine accelerators. More preferably, the vulcanization accelerator is tetramethylthiuram disulfide (accelerator TMTD) and/or N-cyclohexyl-2-benzothiazolesulfenamide (accelerator CZ).

The nitrile rubber matrix of the present invention may be a copolymer of butadiene and acrylonitrile recognized in the art, and preferably, the nitrile rubber matrix has an acrylonitrile structural unit content of 20 to 50% by weight, a 1, 2-butadiene structural unit content of 5 to 15% by weight, and a mooney viscosity of 35 to 90.

Preferably, the lignin of the present invention has a phenolic hydroxyl group content of 3.0 wt% or more and a number average molecular weight of 2500-5500. Preferably, the lignin is at least one selected from alkali lignin obtained by alkali pulping in paper industry, enzymatic lignin extracted from ethanol produced by fermentation of lignocellulose and organic solvent lignin extracted from lignocellulose by organic solvent method. Preferably, the lignin content in the organic solvent lignin, the enzymatic hydrolysis lignin and the alkali lignin is respectively and independently more than or equal to 70 wt%.

Preferably, the activation aid is a mixture of a metal oxide and a fatty acid. In the present invention, the metal oxide is preferably zinc oxide and/or magnesium oxide; the fatty acid is preferably stearic acid.

As mentioned above, the second aspect of the present invention provides a method for preparing a mercapto triazole modified nitrile rubber composite material, which comprises mixing the components of the composition described in the first aspect, and vulcanizing the mixed discharge rubber.

The types of the components involved in the second aspect of the present invention are the same as the types of the corresponding components in the composition according to the first aspect of the present invention, unless otherwise specified, and therefore, in order to avoid repetition, the present invention will not be described herein again, and those skilled in the art should not be construed as limiting the present invention.

In order to further improve the strength and toughness of the vulcanized rubber material obtained from the composition of the invention, according to a particularly preferred embodiment, the operations of mixing the components of the composition and vulcanizing the discharged rubber obtained after mixing comprise:

(1) carrying out first mixing on a nitrile rubber matrix and a main modifier to obtain a first mixed material;

(2) carrying out second mixing on the first mixed material, lignin, an auxiliary modifier or an activating auxiliary agent to obtain a second mixed material;

(3) performing third mixing on the second mixed material, a vulcanizing agent and a vulcanization accelerator, and then discharging to obtain a discharged rubber;

(4) and vulcanizing the discharged rubber.

Preferably, in step (1), the conditions of the first mixing include: the temperature is 100 ℃ and 180 ℃, and the time is 3-15 min.

Preferably, in step (1), the first mixing is carried out in an internal mixer, and the internal mixer rotation speed is 50 to 90rpm, more preferably 60 to 90 rpm.

Preferably, in step (2), the conditions of the second mixing include: the temperature is 100-160 ℃, and the time is 3-15 min.

Preferably, the third mixing conditions include: the temperature is not more than 130 deg.C, and the time is 5-7 min.

The second mixing and the third mixing of the present invention may be performed in an internal mixer. Preferably, the rotation speed of the internal mixer of the second mixing and the third mixing is 30-90 rpm.

The vulcanization process conditions may be those conventional in the art and are well known to those skilled in the art. Preferably, the conditions of the vulcanization include: the temperature is 150 ℃ and 170 ℃, the pressure is 10-20MPa, and the time is 25-40 min. The vulcanization is preferably carried out in a vulcanizer, more preferably the vulcanizer is a press vulcanizer.

In the present invention, the discharged gum may be tabletted, for example, in a two-roll mill, before it is vulcanized. And the discharged glue after tabletting can be placed for 4 to 48 hours, for example.

As mentioned above, the third aspect of the invention provides the mercapto triazole modified nitrile rubber composite material prepared by the method.

As mentioned above, the fourth aspect of the invention provides the application of the above-mentioned mercapto triazole modified nitrile rubber composite material in at least one selected from the group consisting of automobile hoses, printer rollers, sealing materials and foamed heat insulating materials.

Compared with the prior art, the invention also has the following specific advantages:

1. the lignin raw material of the invention has wide source, is renewable, has environment-friendly and biodegradable properties, and has lower cost. Therefore, compared with the nitrile rubber taking carbon black as a reinforcing agent, the modified nitrile rubber composite material has lower cost.

2. The lignin used by the invention has excellent ultraviolet resistance and anti-aging functions, and the composite material has better ultraviolet resistance and anti-aging performance.

3. The nitrile rubber/lignin composite material has higher strength and toughness and good processing performance.

4. In the invention, a specific amount and specific kind of modifier is introduced into a composite system of a rubber matrix and filler lignin, and energy sacrificial bond effect (metal coordination effect and hydrogen bond effect) of non-covalent bond connection is formed between the matrix and the filler; the energy sacrifice bond function can promote the dispersion of the lignin filler in the rubber matrix, can break before the covalent bond under the action of external force, and can repeatedly break and reconstruct, thereby consuming a large amount of external mechanical energy, further improving the strength and toughness of the composite material, and overcoming the problem of poor comprehensive mechanical property of the composite system caused by the non-ideal interface combination between the nitrile rubber and the lignin.

The present invention will be described in detail below by way of examples. In the following examples, various raw materials used are commercially available without specific description.

Nitrile rubber-N230S, acrylonitrile structural unit content 35 wt%, 1, 2-butadiene structural unit content 6.8 wt%, Mooney viscosity 55; purchased from JSR corporation, japan;

nitrile rubber-LG 6240 having an acrylonitrile structural unit content of 34 wt%, a 1, 2-butadiene structural unit content of 6.3 wt%, a mooney viscosity of 42, available from korean LG chemistry;

lignin-enzymatic lignin: the black brown powder is produced by Shandong Longli biological science and technology Co., Ltd, the content of lignin is more than or equal to 80 wt%, the content of phenolic hydroxyl is more than or equal to 3.0 wt%, and the number average molecular weight is 3850;

lignin-solvent lignin: produced by Albizia chinensis Cheng Biotechnology Limited, Guangzhou city, is prepared from bamboo, brown powder, lignin content is not less than 85 wt%, phenolic hydroxyl content is not less than 3.0 wt%, and number average molecular weight is 3719;

3-mercapto-1, 2, 4-triazole as a main modifier: produced by Bailingwei science and technology Limited company, the purity is 99 percent;

main modifier-5- (2-pyridine) -3-mercapto-1, 2, 4-triazole: beijing Huawei Ruiko chemical Co., Ltd, purity 98%;

3-amino-5-mercapto-1, 2, 4-triazole as main modifier: produced by Bailingwei science and technology Limited and has the purity of 98 percent.

co-modifier-ZnCl₂: corridor Longyu chemical industry Co., Ltd, Industrial grade;

co-modifier-CuCl₂: commercial grade, denna luhong environmental protection materials ltd;

co-modifier-zinc methacrylate: shanghai Michelle chemical technology, Inc., analytically pure;

activating auxiliary agent: zinc oxide, stearic acid, Weifang Heng Feng chemical Limited;

vulcanizing agent: sulfur, Heicheng Hechenghuai chemical Limited;

vulcanization accelerator (b): tetramethylthiuram disulfide (accelerator TMTD) and N-cyclohexyl-2-benzothiazolesulfenamide (accelerator CZ) were purchased from Arite east China chemical Co., Ltd, Taizhou.

The rubber processing and testing equipment conditions in the following examples are shown in table 1:

TABLE 1

And (3) testing tensile property: according to the national standard GB/T528-2009, the stretching speed is 500mm/min, and the testing temperature is 23 ℃. The effective portion of the sample had a length of 25mm and a width of 6 mm. For each set of samples, 10 replicates were run and the results averaged.

The amounts of the components in the following examples are in parts by weight, each representing 10 g.

Example 1

Preheating an internal mixer to 105 ℃, adding 100 parts of nitrile rubber N230S, plasticating for 0.5min at the rotating speed of 80rpm, adding 1.5 parts of 3-mercapto-1, 2, 4-triazole into the internal mixer, and fully mixing and reacting for 5min (first mixing). Sequentially adding 15 parts of enzymatic hydrolysis lignin and 1 part of ZnCl into an internal mixer₂4 parts of zinc oxide and 1 part of stearic acid, continuously mixing for 3min at 110 ℃ (second mixing), and discharging for 4 h. And then adding 0.5 part of sulfur, 1.5 parts of TMTD and 0.5 part of CZ into the mixed rubber for third mixing at the mixing temperature of 105 ℃ for 7min, and discharging to obtain the final rubber compound. And tabletting the final rubber compound in a double-roller open mill, and then putting the final rubber compound into a flat vulcanizing machine for vulcanization, wherein the vulcanization temperature is 160 ℃, the vulcanization pressure is 20MPa, and the vulcanization time is 30min, so that a vulcanized rubber sample S1 is prepared.

Example 6

The formulation of the composition used in this example is exactly the same as in example 1, except that the vulcanized rubber is prepared by a different process, specifically:

preheating an internal mixer to 105 ℃, adding 100 parts by weight of nitrile rubber N230S, plasticating for 0.5min at the rotating speed of 80rpm, and sequentially adding 1.5 parts of 3-mercapto-1, 2, 4-triazole, 15 parts of enzymatic hydrolysis lignin and 1 part of ZnCl into the internal mixer₂4 parts of zinc oxide and 1 part of stearic acid, at 110 ℃ for 8min (first mixing), and discharging for 4 h. And then adding 0.5 part of sulfur, 1.5 parts of TMTD and 0.5 part of CZ into the mixed rubber for secondary mixing, wherein the mixing temperature is 105 ℃, the mixing time is 7min, and discharging to obtain the final rubber compound. And tabletting the final rubber compound in a double-roller open mill, and then putting the final rubber compound into a flat vulcanizing machine for vulcanization, wherein the vulcanization temperature is 160 ℃, the vulcanization pressure is 20MPa, and the vulcanization time is 30min, so that a vulcanized rubber sample S6 is prepared.

The remaining examples were carried out using the same procedure as in example 1, unless otherwise specified, and the specific process conditions are shown in Table 2.

Comparative example was carried out using a similar procedure to example 1, except that in comparative examples 1 and 2 no mixing reaction was involved, only the internal mixer was preheated and plasticated at a certain rpm, and the specific process conditions are given in table 2.

TABLE 2

Table 2 (continuation watch)

Table 2 (continuation watch)

Table 2 (continuation watch)

Test example

The products of the examples and the comparative examples are prepared into dumbbell-shaped splines meeting the GB/T528-2009 standard, and a high-iron material universal tester is adopted to test tensile property data, and the results are shown in Table 3.

TABLE 3

As can be seen from the results in Table 3, the formulation of the present invention significantly improves both the tensile strength and the elongation at break of the rubber composite, and greatly increases the energy at break, compared to the prior art.

The rubber composition disclosed by the invention can enable each component in the rubber composition to have better dispersibility in a rubber matrix, and further give play to the characteristics and advantages of lignin as a novel green reinforcing filler for the nitrile rubber; thereby enabling the further produced vulcanized rubber to have improved strength and fracture toughness.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.