CN112592461B

CN112592461B - Modified hydrogenated nitrile rubber material and preparation method and application thereof

Info

Publication number: CN112592461B
Application number: CN202011474387.6A
Authority: CN
Inventors: 岳冬梅; 贾曼曼; 徐蒽云; 张嘉桐; 张立群
Original assignee: Beijing University of Chemical Technology
Current assignee: Beijing University of Chemical Technology
Priority date: 2020-12-14
Filing date: 2020-12-14
Publication date: 2022-02-11
Anticipated expiration: 2040-12-14
Also published as: CN112592461A

Abstract

The invention belongs to the technical field of rubber, and particularly relates to a modified hydrogenated nitrile rubber material with the characteristics of low temperature resistance and high damping, and a preparation method and application thereof. The modified hydrogenated nitrile rubber material is prepared by taking HNBR/PNB block copolymer as a raw material; the HNBR/PNB block copolymer is obtained by modifying NBR or HNBR through olefin metathesis reaction by using a norbornene monomer as a modifier. The obtained block copolymer has the performance characteristics of HNBR and PNB, not only maintains the basic performance of the hydrogenated nitrile rubber, but also can utilize polynorbornene to absorb a large amount of plasticizing oil, and further obtains the modified hydrogenated nitrile rubber material with excellent low-temperature resistance. Meanwhile, due to the annular structure of polynorbornene, the damping performance of the obtained modified hydrogenated nitrile rubber material is also obviously improved.

Description

Modified hydrogenated nitrile rubber material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of rubber, and particularly relates to a modified hydrogenated nitrile rubber material with the characteristics of low temperature resistance and high damping, and a preparation method and application thereof.

Background

Hydrogenated nitrile rubber (HNBR for short) is prepared by selectively hydrogenating carbon-carbon double bonds in nitrile rubber, so that the HNBR not only retains the oil resistance, corrosion resistance and elastic property of NBR, but also shows excellent aging resistance and high temperature resistance, and the mechanical properties such as tensile strength, elongation at break, wear resistance, hardness and the like are improved, and even in an extremely severe environment, the HNBR still can retain better mechanical properties.

Although the hydrogenation of carbon-carbon double bonds endows HNBR with excellent performance, the hydrogenation also brings a serious defect problem to HNBR materials, and the hydrogenated HNBR has a highly ordered polyethylene main chain, is very easy to form a crystalline structure and causes the increase of Tg, so that the low-temperature resistance of HNBR products is poor.

The preparation of the low temperature resistant HNBR material is a current research difficulty. The existing research shows that the low-temperature performance of HNBR is improved by blending ethylene propylene rubber (EPDM) and HNBR, and the Tg is reduced by 3 ℃ when the addition amount of EPDM is 15 percent; however, the Tg of the blend is not reduced and the improvement of the low temperature resistance effect is not obvious when the EPDM dosage is continuously increased.

HNBR/Fluororubber (FKM) blended rubber has better cold resistance and oil resistance, but Atomic Force Microscope (AFM) and TEM analysis show that the blended material is subjected to phase separation and has an obvious sea-island structure; when the blend is stretched, the phase size becomes non-uniform.

Other modification methods have been tried in the prior art, for example, preparing a polynorbornene/nitrile rubber (NBR) mixture and a polynorbornene/pine tar/nitrile rubber mixture by using open-loop polynorbornene, and analyzing the influence of the dynamic damping mechanical property of the blend by a dynamic mechanical test means; however, at a specific frequency (1.5Hz) and within a certain temperature range (-20 to 50 ℃), the damping performance of NBR is greatly improved by polynorbornene, but the Tg value of the blend is shifted to a high temperature, and the high damping and low temperature resistance are difficult to be combined.

And the modification method for preparing HNBR by adding proper monomers for copolymerization reaction or grafting reaction and then hydrogenation in the NBR synthesis process can effectively destroy the crystal structure of HNBR, thereby improving the low temperature resistance of HNBR. However, due to the introduction of the flexible side group or the copolymerization of the third monomer, although the low temperature resistance is improved, the oil resistance and the mechanical property of the flexible side group may be reduced to a certain extent, and the low temperature resistance, the oil resistance and the mechanical property of the flexible side group are difficult to combine.

Disclosure of Invention

The first purpose of the invention is to provide a modified hydrogenated nitrile rubber material. The modified HNBR material with good low temperature resistance and damping performance is prepared by introducing olefin metathesis reaction into HNBR modification; meanwhile, the oil resistance and the mechanical property of the obtained material are not influenced, and the material still keeps good oil resistance and mechanical property, even better than the virgin rubber.

The modified hydrogenated nitrile rubber material is prepared by taking HNBR/PNB block copolymer as a raw material; the HNBR/PNB block copolymer is obtained by modifying NBR or HNBR through olefin metathesis reaction by using a norbornene monomer as a modifier.

After intensive research and continuous trial, we find that the (hydrogenated) nitrile rubber is modified by using a norbornene monomer as a modifier and adopting an olefin metathesis process, the obtained block copolymer has the performance characteristics of HNBR and PNB, not only is the basic performance of the hydrogenated nitrile rubber maintained, but also a large amount of plasticizing oil (as much as 60%) can be absorbed by polynorbornene, and then the modified hydrogenated nitrile rubber material with excellent low-temperature resistance is obtained. Meanwhile, due to the annular structure of polynorbornene, the damping performance of the obtained modified hydrogenated nitrile rubber material is also obviously improved.

Specifically, the modified hydrogenated nitrile rubber material is prepared by performing olefin metathesis reaction on nitrile rubber NBR and polynorbornene PNB, and then performing hydrogenation reaction;

or the modified nitrile butadiene rubber is directly prepared from hydrogenated nitrile butadiene rubber HNBR and polynorbornene PNB through olefin metathesis reaction.

The HNBR is selected from hydrogenated nitrile rubber with acrylonitrile content of 20-45% and hydrogenation degree of 0-92%.

The olefin metathesis reaction is carried out in an organic solvent; the organic solvent is selected from one or more of tetrahydrofuran, toluene, xylene, chlorobenzene, dichloromethane or trichloromethane, and is preferably chlorobenzene. Compared with other organic solvents, the chlorobenzene is used as the solvent, so that the dissociation of the catalyst is facilitated, an active center is formed, and the reaction is initiated.

In the invention, the mass ratio of the norbornene monomer to the HNBR is controlled to be (0.1-1): 1, preferably (0.4-1): 1, further preferably (0.4-0.8): 1; more preferably (0.6-0.8): 1. Along with the increase of the dosage proportion of the norbornene monomer, the more the proportion of the polynorbornene chain segment in the obtained copolymer is, the better the low temperature resistance of the corresponding obtained modified hydrogenated nitrile-butadiene rubber material is.

In the invention, the mass concentration of the HNBR in the organic solvent is controlled to be 1-10%, preferably 4-8%, and the mass concentration is controlled to be in the range, so that the contact between the active center of the catalyst and a macromolecular chain is facilitated, and the reaction is initiated.

In the invention, the reaction conditions of the olefin metathesis reaction are mild, and the reaction can be finished at normal temperature and normal pressure, for example, the reaction is carried out at 0-120 ℃ for 1-10 h. Through research, the olefin double decomposition reaction is controlled to be carried out at the temperature of 10-50 ℃, so that the advantages of being beneficial to the dissociation of a catalyst and generating more active centers so as to initiate the reaction are achieved, meanwhile, the reaction time (such as 4-8h) can be reasonably shortened, and the reaction efficiency is improved.

As one of the preferred embodiments of the present invention, the HNBR/PNB block copolymer is obtained by the following method: under the action of a catalyst, HNBR reacts with norbornene monomers in an organic solvent; wherein the mass fraction of the HNBR in the organic solvent is controlled to be 4-8%, and the addition amount of the norbornene monomer is 40-80% of the mass of the HNBR; and the reaction is carried out for 7 to 8 hours at the temperature of between 45 and 50 ℃; at the moment, the PNB content of the HNBR/PNB block copolymer is higher, and the cost of raw materials is lower.

By controlling the addition amount of the norbornene monomer, the mass fraction of HNBR and the reaction conditions, all factors act synergistically, so that the HNBR/PNB block copolymer with more PNB is obtained by using relatively less monomers, the reaction yield is higher, the side reaction is less, and the group tolerance is higher.

In addition, the product obtained by the reaction can be treated by ethanol precipitation, washing and drying.

The catalyst is a Grubbs I catalyst, a Grubbs II catalyst or a Hoveyda-Grubbs catalyst, preferably a Grubbs I catalyst.

The dosage of the catalyst is 0.001-5%, preferably 0.01-2% of the total mole number of the double bonds in the HNBR and the norbornene monomer, under the condition, the molecular weight of the obtained material is moderate, and is 10 multiplied by 10⁴～15×10⁴Thereby avoiding the situation that the physical and mechanical properties of the material are reduced due to low molecular weight or the processing property is influenced due to the rise of the Mooney viscosity of the material caused by too high molecular weight.

In the invention, the raw material of the modified hydrogenated nitrile rubber material also comprises plasticizing oil. The plasticizing oil is one or more of naphthenic oil, paraffin oil or aromatic oil; preferred are naphthenic oils, which can be absorbed in large amounts by the HNBR/PNB block copolymer, thereby significantly improving the low temperature resistance of the modified hydrogenated nitrile rubber material.

Preferably, the raw materials of the modified hydrogenated nitrile rubber material comprise the following components in parts by weight: 100 parts of HNBR/PNB block copolymer, 1-80 parts of naphthenic oil, 1-50 parts of carbon black N3301, 5-6 parts of zinc oxide, 1-2 parts of stearic acid, 4451-2 parts of anti-aging agent, 0.1-3 parts of sulfur and 0.1-2 parts of accelerator NS. Through screening the assistant, the assistant is compounded with the HNBR/PNB block copolymer and the naphthenic oil to play a synergistic effect, and the dosage proportion of each component is optimized and adjusted, so that the problems of low vulcanization degree and low vulcanization rate caused by mismatching of the conventional functional assistant raw material with the HNBR/PNB block copolymer and the naphthenic oil in the preparation process are avoided. For example, carbon black is used as a reinforcing agent, which can improve the mechanical properties of rubber; the zinc oxide and the stearic acid are used in a matching way and can be used as a vulcanization activator, so that the vulcanization efficiency is improved; the stearic acid also has certain softening and plasticizing effects, is beneficial to improving the dispersion degree of the carbon black and the zinc oxide in the rubber material, is more beneficial to the reaction and improves the product quality.

Further preferably, the modified hydrogenated nitrile rubber material comprises the following components in parts by weight: 100 parts of HNBR/PNB block copolymer, 60 parts of naphthenic oil, 33040 parts of carbon black N, 5 parts of zinc oxide, 1 part of stearic acid, 4451 parts of anti-aging agent, 2.5 parts of sulfur and 0.6 part of accelerator NS.

The second purpose of the invention is to provide a preparation method of the modified hydrogenated nitrile rubber material, which comprises the following steps: mixing HNBR/PNB segmented copolymer, naphthenic oil, carbon black N330, zinc oxide, stearic acid, an anti-aging agent, sulfur and an accelerator NS; vulcanizing the obtained rubber compound; wherein the vulcanization conditions are as follows: the temperature is 140 ℃ and 170 ℃, and the pressure is 6-18 MPa.

Preferably, the vulcanizing time is 15-30 min.

The third purpose of the invention is to provide the application of the modified hydrogenated nitrile rubber material in automobile fuel system parts, automobile transmission belts, well protection covers, oil well packer rubber cylinders, aerospace sealing elements, tank track liners and foamed shock-absorbing materials.

The invention has the beneficial effects that:

(1) according to the invention, the olefin metathesis reaction is introduced into the modification of the hydrogenated nitrile-butadiene rubber for the first time, the modification can be carried out at normal temperature and normal pressure, the operation is simple, and the requirement on equipment is low;

(2) the HNBR/PNB block copolymer of the invention can absorb naphthenic oil plasticizing oil of up to 60 percent; compared with the hydrogenated nitrile rubber raw rubber, the glass transition temperature of the modified hydrogenated nitrile rubber material is reduced by 11 ℃, and the low-temperature resistance is better;

(3) compared with the hydrogenated nitrile rubber raw rubber, the modified hydrogenated nitrile rubber material has the advantages of increased damping factor, widened damping temperature range and improved damping performance.

Drawings

FIG. 1 is a nuclear magnetic spectrum of the HNBR/PNB block copolymer obtained.

FIG. 2 is a comparison of DSC spectra of the obtained modified hydrogenated nitrile rubber material and hydrogenated nitrile rubber crude rubber.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

Example 1

This example provides a method for preparing an HNBR/PNB block copolymer, comprising:

(1) dissolving hydrogenated nitrile-butadiene rubber with acrylonitrile content of 33 wt% and hydrogenation degree of 92% in chlorobenzene to prepare hydrogenated nitrile-butadiene rubber liquid with mass concentration of 10%;

(2) 200g of hydrogenated nitrile rubber (20 g in terms of conversion) with glue solution mass concentration of 10% is placed in a 500ml three-neck flask, 2g of norbornene monomer (10% in mass fraction) is weighed and added into the hydrogenated nitrile rubber solution, and then Grubbs I-substituted catalyst is added into the mixed rubber solution, stirred and reacted for 8 hours at 50 ℃;

the molar amount of Grubbs I catalyst used was 0.025% of the sum of the molar amounts of the double bonds in the reactants.

(3) And slowly adding the product into ethanol, washing the precipitate, and drying in a vacuum oven to constant weight to obtain the product.

The chain segment proportion of the HNBR/PNB block copolymer obtained by the reaction is as follows: hydrogenated nitrile rubber segment/polynorbornene segment 87/13.

Examples 2 to 8:

compared with the example 1, the difference is that the addition amount of the norbornene monomer is different, and is respectively 20%, 30%, 40%, 50%, 60%, 80% and 100% of the mass of the hydrogenated nitrile rubber.

FIG. 1 is a nuclear magnetic spectrum of the HNBR/PNB block copolymer obtained.

The nuclear magnetic spectrum of the HNBR/PNB block copolymer is used for calculating the chain segment proportion of hydrogenated nitrile rubber and polynorbornene in the chain segment, and the chain segment proportion is shown in the following table 1:

TABLE 1

	Hydrogenated nitrile rubber segment content (%)	Polynorbornene segment content (%)
			Example 1 (10%)	87	13
Example 2 (20%)	75	25
			Example 3 (30%)	68	32
Example 4 (40%)	50	50
			Example 5 (50%)	44	56
Example 6 (60%)	42	58
			Example 7 (80%)	35	65
Example 8 (100%)	44	56

As can be seen from Table 1, as the addition ratio of norbornene monomer was increased, the content of polynorbornene segment in the segment of the HNBR/PNB block copolymer was also increased; when the addition amount of the norbornene monomer is more than 50 percent of HNBR, the content of the polynorbornene chain segment in the chain segment of the HNBR/PNB block copolymer is slowly increased; when the addition amount of the norbornene monomer reaches 80% of HNBR, the content of the polynorbornene segment in the segment of the HNBR/PNB block copolymer is reduced.

Examples 9 to 14:

the embodiment provides a preparation method of a low-temperature-resistant high-damping modified hydrogenated nitrile rubber material, which comprises the following steps:

100 parts of each of HNBR/PNB block copolymers obtained in example 1 (10%), example 2 (20%), example 4 (40%), example 6 (60%), example 7 (80%), and example 8 (100%) were kneaded together with 60 parts of naphthenic oil, 33040 parts of carbon black N, 5 parts of zinc oxide, 1 part of stearic acid, 4451 parts of antioxidant, 1.5 parts of sulfur, and 0.6 part of accelerator NS in an internal mixer; and vulcanizing the rubber compound for 10-25 min at 160 ℃ and 10MPa by using a flat vulcanizing machine to obtain the rubber compound.

Comparative example 1

This comparative example provides a process for the preparation of a hydrogenated nitrile rubber material (virgin rubber) which differs from example 9 in that the HNBR/PNB block copolymer is replaced with hydrogenated nitrile rubber;

the preparation method comprises the following steps:

100 parts of hydrogenated nitrile rubber, 60 parts of naphthenic oil, 40 parts of carbon black N33040 parts, 5 parts of zinc oxide, 1 part of stearic acid, 4451 parts of anti-aging agent, 1.5 parts of sulfur and 0.6 part of accelerator NS are added into an internal mixer for mixing; and vulcanizing the rubber compound for 10-25 min at 160 ℃ and 10MPa by using a flat vulcanizing machine to obtain the rubber compound.

Performance testing

1. Glass transition temperature

The glass transition temperature of the gum samples was tested using a Differential Scanning Calorimeter (DSC):

The glass transition temperature of the virgin rubber obtained in the comparative example 1 is-23.8 ℃;

the glass transition temperature of the modified hydrogenated nitrile rubber materials obtained in examples 9 to 14 is reduced, and the glass transition temperature is reduced more along with the increase of the PNB content in a certain range; when the PNB content was increased to 60% (example 6), the glass transition temperature decreased to a minimum of-32.6 ℃, and when the PNB content continued to increase to 100%, the glass transition temperature tended to increase again, as shown in table 2 and fig. 2; but overall, the low temperature resistance of the obtained modified hydrogenated nitrile rubber material is remarkably improved.

TABLE 2

	Glass transition temperature (Tg,. degree.C.)
		Comparative example 1	-23.8
Example 9 (corresponding to example 1)	-25.4
		Example 10 (corresponding to example 2)	-25.1
Example 11 (corresponding to example 4)	-31.1
		Example 12 (corresponding example 6)	-32.6
Example 13 (corresponding example 7)	-30.8
		Example 14 (corresponding example 8)	-28.1

2. Damping performance

The higher the loss factor value is, the wider the corresponding temperature range is, and the better the damping performance of the rubber material is.

TABLE 3

As can be seen from Table 3, as the PNB content increased, the loss factor peak increased, and the temperature range of tan delta > 0.3 The width of the enclosure is wide (generally, the temperature range with tan delta > 0.3 is called damping temperature range and is used for representing the damping performance of the material).

Wherein, when the PNB content is 60% (example 6), the peak value of tan delta can reach 0.98, and the damping temperature range is expanded to-31.7 The damping performance of the material is obviously improved at the temperature of minus 1.5 ℃.

3. Oil resistance and mechanical property

Tests show that the modified hydrogenated nitrile rubber materials prepared from the HNBR/PNB block copolymers obtained in examples 1 to 8 in examples 9 to 14 have no influence on oil resistance and mechanical properties, and still maintain good oil resistance and mechanical properties, even better than virgin rubber.

TABLE 4 comparison of mechanical properties of different sizing materials

TABLE 5 comparison of oil resistance of different stocks

	Comparative example 1	Example 9	Example 10	Example 11	Example 12	Example 13
							Rate of change of mass/%)	-1.6	-1.9	-4.1	1.2	5.2	16.3

Note: and (3) testing conditions are as follows: soaking in No. 15 aviation standard oil at 150 deg.C for 24 h.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. A modified hydrogenated nitrile rubber material is characterized in that the modified hydrogenated nitrile rubber material is prepared by taking HNBR/polynorbornene PNB block copolymer as a raw material; the HNBR/PNB block copolymer is obtained by modifying HNBR through olefin metathesis reaction by using a norbornene monomer as a modifier;

in the olefin metathesis reaction, the mass ratio of the norbornene monomer to the HNBR is controlled to be (0.1-1): 1.

2. the modified hydrogenated nitrile rubber material according to claim 1, wherein said modified hydrogenated nitrile rubber material is prepared from hydrogenated nitrile rubber HNBR and polynorbornene PNB by olefin metathesis.

3. The modified hydrogenated nitrile rubber material according to claim 2, wherein the olefin metathesis reaction is carried out in an organic solvent; the organic solvent is selected from one or more of tetrahydrofuran, toluene, xylene, chlorobenzene, dichloromethane or trichloromethane;

controlling the mass concentration of the HNBR in the organic solvent to be 1-10%;

and/or, controlling the olefin metathesis reaction to be carried out at 10-50 ℃.

4. The modified hydrogenated nitrile rubber material according to claim 3, wherein the weight ratio of said norbornene monomer to said HNBR in said olefin metathesis reaction is controlled to be (0.4-1): 1.

5. the modified hydrogenated nitrile rubber material according to claim 4, wherein said HNBR/PNB block copolymer is obtained by a process comprising: under the action of a catalyst, HNBR reacts with norbornene monomers in an organic solvent;

wherein the mass fraction of HNBR in the organic solvent is controlled to be 4-8%; the addition amount of the norbornene monomer is 40-80% of the mass of the HNBR; and the reaction is carried out for 7-8h at 45-50 ℃.

6. The modified hydrogenated nitrile rubber material according to claim 5, wherein the feedstock for said modified hydrogenated nitrile rubber material further comprises a plasticizing oil;

the plasticizing oil is naphthenic oil, paraffin oil or aromatic oil.

7. The modified hydrogenated nitrile rubber material according to claim 6, wherein said plasticizing oil is naphthenic oil.

8. The modified hydrogenated nitrile rubber material according to claim 6 or 7, wherein the raw material comprises the following components in parts by weight: HNBR/PNB block copolymer: 100 parts, naphthenic oil: 1-80 parts of carbon black N330: 1-50 parts of zinc oxide: 5-6 parts of stearic acid: 1-2 parts; anti-aging agent 445: 1-2 parts; sulfur: 0.1-3 parts; and (2) an accelerator NS: 0.1-2 parts.

9. A process for the preparation of a modified hydrogenated nitrile rubber material according to any of claims 1 to 8, comprising: mixing HNBR/PNB segmented copolymer, naphthenic oil, carbon black N330, zinc oxide, stearic acid, an anti-aging agent, sulfur and an accelerator NS; vulcanizing the obtained rubber compound; wherein the vulcanization conditions are as follows: the temperature is 140 ℃ and 170 ℃, and the pressure is 6-18 MPa.

10. Use of the modified hydrogenated nitrile rubber material according to any one of claims 1 to 8 in automotive fuel system parts, automotive transmission belts, well protection covers, oil well packer rubber cylinders, aerospace seals, tank track liners, foamed shock absorbers.