An antiozonant for rubber, a preparation method and application thereof, and a rubber

Abstract

The application discloses an anti-ozone agent for rubber, which contains both arylamine group functional groups and carbon-carbon double bonds in the molecular structure. The application also discloses a preparation method and application of the anti-ozone agent and a rubber. The anti-ozone agent for rubber contains arylamine group functional groups and carbon-carbon double bonds in the molecule, which synergize with each other, migrate to the surface of the rubber product, can react with ozone, prevent the rubber molecular chain from being aged and cracked by ozone, fully realize the anti-ozone effect, and have a long continuous action time, thereby being beneficial to prolonging the service life of the rubber.

Description

Technical Field

[0001] The present invention belongs to the field of rubber materials, and in particular relates to a rubber additive, a preparation method and application thereof, and a rubber. Background Art

[0002] As environmental pollution becomes increasingly serious, the concentration of ozone in the atmosphere is gradually increasing. Rubber products, especially those made from rubber containing unsaturated carbon-carbon double bonds in the molecular chain, are significantly affected by ozone during storage and use, causing discoloration and ozone cracking on the surface of the products, seriously affecting the appearance and function of rubber products.

[0003] Paraphenylenediamine organic compounds are the most commonly used chemical antiozonants in the rubber industry. After being added to rubber composites, they gradually diffuse onto the rubber surface and react with ozone, protecting the rubber from ozone attack until the ozone is completely consumed, thereby providing ozone protection. Common paraphenylenediamine antiozonants include dialkyl-substituted paraphenylenediamines, alkylaryl-substituted paraphenylenediamines, and diaryl-substituted paraphenylenediamines. Dialkyl-substituted paraphenylenediamines offer good antiozonation effects, but are highly volatile and have poor sustained effects. Diaryl-substituted paraphenylenediamines offer good sustained effects, but are less effective than dialkyl-substituted paraphenylenediamines. Alkylaryl-substituted paraphenylenediamines offer effects somewhere in between. Existing antiozonants struggle to achieve both good and long-lasting antiozonation effects. Therefore, designing and synthesizing an antiozonant with both good and long-lasting antiozonation effects is of great significance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide an antiozonant for rubber with good anti-ozone effect and long lasting action time, as well as its preparation method, application and a rubber.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0006] An antiozonant for rubber, wherein the molecular structure of the antiozonant contains both an aromatic amine functional group and a carbon-carbon double bond.

[0007] In the above antiozonants, preferably, the aromatic amino functional group includes one or more of dialkylphenylamine, alkylphenylamine and phenylamine.

[0008] In the above antiozonants, preferably, the carbon-carbon double bond is connected to two aromatic amine functional groups to form a conjugated structure.

[0009] Among the above antiozonants, preferably, the molecular structure of the antiozonant is as follows:

[0010] ;

[0011] Among them, R 1 、R 2 、R 3 、R 4 is hydrogen, or is the same or different straight or branched chain alkyl group of 1 to 8 carbon atoms. More preferably, R 1 、R 2 、R 3 、R 4 The alkyl groups are straight or branched chain alkyl groups of 1 to 3 carbon atoms, which may be the same or different.

[0012] The antiozonant of the present invention is used for ozone protection in rubber. Its molecular weight must be properly controlled to ensure an appropriate migration rate. If the antiozonant migrates too slowly from the interior of the rubber to the surface, it will not have an antiozonating effect. If it migrates too quickly and is highly volatile, the sustained antiozonating effect will be poor. This structural antiozonant, by controlling the molecular weight of the terminal branches, helps ensure an appropriate molecular weight, possesses an appropriate migration rate and volatility, and can maintain a steady-state concentration on the surface of the rubber product, resulting in a better sustained antiozonating effect.

[0013] As a general technical concept, the present invention also provides a method for preparing the above-mentioned antiozonant, comprising the following steps: reacting a quaternary phosphine salt with a base to generate methylenetriphenylphosphine, and subjecting the methylenetriphenylphosphine to a Wittig reaction with a first raw material to obtain the antiozonant;

[0014] Among them, the structural molecular formula of the first raw material is as follows:

[0015] .

[0016] In the above preparation method, preferably, the quaternary phosphine salt is reacted with a base to produce methylenetriphenylphosphine, comprising the following steps: under the protection of an inert gas, the quaternary phosphine salt and an organic solvent are configured into a mixed liquid, and an alkaline solution with a mass concentration of 2-50wt% (preferably 2-30wt%) is added under stirring at 0-20°C (preferably 0-10°C), and the stirring reaction is continued for 0.1-3h (preferably 0.3-2h) to obtain a methylenetriphenylphosphine mixed liquid; the quaternary phosphine salt comprises one or more of methyltriphenylphosphine chloride, methyltriphenylphosphine bromide and methyltriphenylphosphine iodide, the organic solvent comprises one or more of tetrahydrofuran, dimethylformamide, dimethyl sulfoxide and diethyl ether; the base comprises one or more of potassium tert-butoxide, sodium tert-butoxide, lithium tert-butoxide, sodium hydroxide and sodium carbonate; and the molar ratio of the base to the quaternary phosphine salt is (1-2):1 (preferably (1-1.2):1).

[0017] In the above preparation method, preferably, methylenetriphenylphosphine and the first raw material are subjected to a Wittig reaction, comprising the following steps: under the protection of an inert gas, the first raw material is dissolved in an organic solvent, mixed with methylenetriphenylphosphine under stirring at 0-20°C (preferably 0-10°C), and the reaction is continued with stirring from room temperature to reflux temperature (preferably at reflux temperature) for 4-48 hours (preferably 5-12 hours). After the reaction, the reaction mixture is poured into excess deionized water, and the organic layer is separated. The organic layer is washed with a saturated sodium bicarbonate aqueous solution until neutral, and then anhydrous magnesium sulfate is added and stirred to dry for a day and night, filtered, and the filtrate is rotary evaporated to obtain a crude product. The crude product is separated by column chromatography, rotary evaporated, and vacuum dried at 10-40°C (preferably 20-35°C) to constant weight to obtain an antiozonant; the organic solvent comprises one or more of tetrahydrofuran, dimethylformamide, dimethyl sulfoxide and diethyl ether; and the molar ratio of the quaternary phosphine salt to the first raw material is (1-2):1 (preferably (1-1.6):1).

[0018] As a general technical concept, the present invention also provides a use of the above antiozonant in ozone protection of rubber materials.

[0019] As a general technical concept, the present invention also provides a rubber comprising a rubber matrix and an additive, wherein the rubber matrix contains carbon-carbon double bonds in its molecular chain, and the additive comprises an antiozonant, which is the antiozonant described above. The rubber matrix comprises natural rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, chloroprene rubber, nitrile rubber, and combinations thereof in varying proportions.

[0020] The aromatic amine functional groups in the antiozonant molecules for rubber of the present invention include dialkylphenylamine, alkylphenylamine or phenylamine, which are easy to react with the electron-withdrawing reagent ozone, consuming ozone while preventing ozone from attacking the unsaturated carbon-carbon double bonds in the rubber molecular chain. In addition, the reaction product forms a charred protective film on the surface of the product, preventing ozone from continuing to penetrate into the inner layer of the rubber and destroying the rubber molecular chain; the carbon-carbon double bond in the antiozonant molecule can replace the carbon-carbon double bond in the rubber molecular chain and react with ozone, further enhancing the anti-ozone effect. The carbon-carbon double bond in the antiozonant molecule is connected to the two aromatic amine functional groups and forms a conjugated structure. On the one hand, this structural form is conducive to the synergistic effect of the aromatic amine functional groups and the carbon-carbon double bond, thereby enhancing the anti-ozone effect through the synergistic effect. On the other hand, the two aromatic amine functional groups contained in the structure can react with the aldehyde and ketone groups generated after the rubber macromolecule breaks due to ozone aging, playing a similar "cross-linking" role, preventing the rubber molecular chain from further degradation and inhibiting the generation of ozone cracking. In addition, the antiozonant of the present invention has a moderate molecular weight, an appropriate migration rate and volatility, and can timely maintain a steady concentration on the surface of the rubber product. Therefore, the antiozonant has a better sustained effect.

[0021] In the present invention, the aromatic amine functional group and the carbon-carbon double bond have a synergistic effect, and the combination of the two needs to be limited. If the above two functional groups are not contained at the same time, for example, if the aromatic amine functional group is not contained, the anti-ozone effect is reduced; if the carbon-carbon double bond is not contained, the anti-ozone effect cannot be further improved. If the carbon-carbon double bond is not connected with the two aromatic amine functional groups to form a conjugated structure, on the one hand, the aromatic amine functional group and the carbon-carbon double bond cannot play a synergistic role, and the anti-ozone effect is not ideal. On the other hand, the aromatic amine functional group cannot play a similar "cross-linking" role and cannot inhibit the occurrence of rubber ozone cracking. In rubbers containing carbon-carbon double bonds in the molecular chain, the above three situations cannot achieve better anti-ozone and its sustained effect.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] The antiozonant molecule for rubber of the present invention contains an aromatic amine functional group and a carbon-carbon double bond, which synergistically migrate to the surface of the rubber product and react with ozone to prevent the rubber molecular chain from being broken and cracked due to ozone aging, thereby fully achieving the anti-ozon effect and having a long lasting effect, which is beneficial to extending the service life of the rubber.

[0024] The preparation method of the present invention has high universality, is simple and easy to operate, can share organic synthesis instruments and equipment, is easy to realize industrial production, and has good market application value in the rubber industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 is the antiozonant A1 (1,1-bis(4-dimethylaminophenyl)ethylene) in Example 1 1 H NMR spectrum.

[0027] Figure 2 This is the MS spectrum of the antiozonant A1 (1,1-bis(4-dimethylaminophenyl)ethylene) in Example 1. DETAILED DESCRIPTION

[0028] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0029] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0030] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0031] Example 1:

[0032] An antiozonant for rubber, the molecular structure is as follows:

[0033] .

[0034] The preparation method of the above-mentioned antiozonant for rubber comprises the following steps:

[0035] (1) Under nitrogen protection, weigh 19 g of potassium tert-butoxide and 140 g of tetrahydrofuran to prepare a potassium tert-butoxide solution. Weigh 58 g of methyltriphenylphosphine bromide and 90 g of tetrahydrofuran and add them to a three-necked round-bottom flask. Add the potassium tert-butoxide solution while stirring at 0°C and continue stirring for 2 h to obtain a methylenetriphenylphosphine mixed solution.

[0036] (2) Under nitrogen protection, 27 g of 4,4'-bis(dimethylamino)benzophenone and 100 g of tetrahydrofuran were weighed to prepare a solution, which was added to the above-mentioned methylenetriphenylphosphine mixed solution at 0°C with stirring, and then the temperature was raised to reflux and the reaction was continued with stirring for 7 h. The reaction mixture was poured into excess deionized water, and the organic layer was separated. The organic layer was washed with a saturated sodium bicarbonate aqueous solution until neutral, and then anhydrous magnesium sulfate was added and stirred to dry for a day and night. The filtrate was filtered and rotary evaporated to obtain a crude product. The crude product was separated by column chromatography, rotary evaporated, and vacuum dried at 35°C to constant weight to obtain the antiozonant of this example, the product name is abbreviated as A1, and the yield is about 92%.

[0037] Figure 1 is the antiozonant A1 in Example 1 1 H NMR spectrum, Figure 2 is the MS diagram of antiozonant A1 in Example 1, Figure 1 and Figure 2 It can be seen that the target product antiozonant A1 (1,1-bis(4-dimethylaminophenyl)ethylene) was synthesized in this example.

[0038] Example 2:

[0039] An antiozonant for rubber, the molecular structure is as follows:

[0040] .

[0041] The preparation method of the above-mentioned antiozonant for rubber comprises the following steps:

[0042] (1) Under nitrogen protection, weigh 15 g of sodium tert-butoxide and 55 g of tetrahydrofuran to prepare a sodium tert-butoxide solution. Weigh 43 g of methyltriphenylphosphine chloride and 90 g of tetrahydrofuran and add them to a three-necked round-bottom flask. Add the sodium tert-butoxide solution while stirring at 4°C and continue stirring for 1 h to obtain a methylenetriphenylphosphine mixed solution.

[0043] (2) Under nitrogen protection, 32 g of 4,4'-bis(diethylamino)benzophenone and 100 g of tetrahydrofuran were weighed to prepare a solution, which was added to the above-mentioned methylenetriphenylphosphine mixed solution with stirring at 4°C, and then the temperature was raised to reflux and the stirring reaction was continued for 6 h. The reaction mixture was poured into excess deionized water, and the organic layer was separated. The organic layer was washed with a saturated sodium bicarbonate aqueous solution until neutral, and then anhydrous magnesium sulfate was added and stirred to dry for a day and night. The filter was filtered and the filtrate was rotary evaporated to obtain a crude product. The crude product was separated by column chromatography, rotary evaporated, and vacuum dried at 23°C to constant weight to obtain the antiozonant of this example, the product name is abbreviated as A2, and the yield is about 90%.

[0044] Application Example 1:

[0045] Compounds were prepared according to the formulations shown in Table 1. Compounds 1#, 2#, 3#, and 4# were all mixed using conventional mixing techniques. Compound 1# did not contain an antiozonant, while compounds 2# and 3# contained 6PPD, an antiozonant containing only aromatic amine functional groups, and AFS, an antiozonant containing only carbon-carbon double bonds, respectively. Compound 4#, in contrast, directly contained antiozonant A1. Comparison of the properties of the compounds obtained from the four formulations demonstrates the antiozonant effectiveness of antiozonant A1. Compounds without aromatic amine functional groups or carbon-carbon double bonds exhibit poor antiozonant effects.

[0046] Table 1: Basic formula of natural rubber composite materials (parts by mass)

[0047]

[0048] The rubber compound prepared according to the formulation shown in Table 1 was vulcanized at 150°C for 15 minutes. The properties of the resulting vulcanized rubber are shown in Table 2. As shown in Table 2, ozone cracking occurred in the vulcanized rubber after 24 hours when antiozonant A1 was not added or when antiozonant AFS was added. Ozone cracking occurred in the vulcanized rubber after 48 hours when antiozonant 6PPD was added. However, no ozone cracking occurred in the vulcanized rubber after 168 hours when antiozonant A1 was added. This indicates that antiozonant A1 has a good anti-ozone effect on natural rubber composites, effectively improving the ozone resistance of the vulcanized rubber, and its anti-ozone effect is long-lasting.

[0049] Table 2: Properties of natural rubber vulcanizates

[0050]

[0051] Application Example 2

[0052] The rubber compounds were prepared according to the formulations shown in Table 3, and 5# and 6# were both prepared by the conventional mixing process.

[0053] Table 3: Basic formulation of butadiene-styrene rubber composite (parts by mass)

[0054]

[0055] The rubber compounds prepared according to the formulations shown in Table 3 were vulcanized at 150°C for 15 min, and the properties of the obtained vulcanized rubber were shown in Table 4. As shown in Table 4, the anti-ozone agent A2 had a good anti-ozone effect on the butadiene-styrene rubber composite, which could effectively improve the ozone resistance of the vulcanized rubber, and had a good continuous anti-ozone effect.

[0056] Table 4: Properties of butadiene-styrene rubber vulcanizate

[0057]

[0058] Application Example 3

[0059] The rubber compounds were prepared according to the formulations shown in Table 5, and 7# and 8# were both prepared by the conventional mixing process.

[0060] Table 5: Basic formulation of butadiene rubber composite (parts by mass)

[0061]

[0062] The rubber compounds prepared according to the formulations shown in Table 5 were vulcanized at 150°C for 20 min, and the properties of the obtained vulcanized rubber were shown in Table 6. As shown in Table 6, the anti-ozone agent A1 had a good anti-ozone effect on the butadiene rubber composite, which could effectively improve the ozone resistance of the vulcanized rubber, and had a good continuous anti-ozone effect.

[0063] Table 6: Properties of butadiene rubber vulcanizate

[0064]

[0065] Application Example 4

[0066] The rubber compounds were prepared according to the formulations shown in Table 7, and 9# and 10# were both prepared by the conventional mixing process.

[0067] Table 7: Basic formulation of isoprene rubber composite (parts by mass)

[0068]

[0069] The rubber compound prepared according to the formulation shown in Table 7 was vulcanized at 150°C for 15 minutes. The properties of the resulting vulcanized rubber are shown in Table 8. As shown in Table 8, antiozonant A2 has a good anti-ozone effect on the isoprene rubber composite material, effectively improving the ozone resistance of the vulcanized rubber, and the anti-ozone effect is good and lasts for a long time.

[0070] Table 8: Properties of isoprene rubber vulcanizate

[0071]

[0072] Application Example 5:

[0073] The rubber compound was prepared according to the formula shown in Table 9, and 11# and 12# were mixed according to the conventional process.

[0074] Table 9: Basic formula of chloroprene rubber composite materials (parts by mass)

[0075]

[0076] The rubber compound prepared according to the formulation shown in Table 9 was vulcanized at 150°C for 30 min. The properties of the resulting vulcanized rubber are shown in Table 10. As shown in Table 10, antiozonant A1 has a good anti-ozone effect on the chloroprene rubber composite material, effectively improving the ozone resistance of the vulcanized rubber, and the anti-ozone effect is good and sustained.

[0077] Table 10: Properties of chloroprene rubber vulcanizate

[0078]

[0079] Application Example 6:

[0080] The rubber compounds were prepared according to the formula shown in Table 11. 13#, 14#, 15# and 16# were all mixed according to the conventional mixing process.

[0081] Table 11: Basic formula of nitrile rubber composite materials (parts by mass)

[0082]

[0083] The rubber compound prepared according to the formulation shown in Table 11 was vulcanized at 150°C for 40 min. The properties of the resulting vulcanized rubber are shown in Table 12. As shown in Table 12, antiozonant A2 has a good anti-ozone effect on the nitrile rubber composite material, effectively improving the ozone resistance of the vulcanized rubber, and the anti-ozone effect is good and sustained.

[0084] Table 12: Properties of Nitrile Rubber Vulcanizate

[0085]

[0086] Application Example 7:

[0087] The rubber compound was prepared according to the formula shown in Table 13, and both 17# and 18# were mixed according to the conventional mixing process.

[0088] Table 13: Basic formula of rubber composite materials containing natural rubber, butadiene rubber and chloroprene rubber (parts by mass)

[0089]

[0090] The rubber compound prepared according to the formulation shown in Table 13 was vulcanized at 150°C for 20 min. The properties of the resulting vulcanized rubber are shown in Table 14. As shown in Table 14, antiozonant A1 has a good anti-ozone effect on natural rubber, butadiene rubber, and chloroprene rubber composites, effectively improving the ozone resistance of the vulcanized rubber, and the anti-ozone effect is good and sustained.

[0091] Table 14: Properties of natural rubber, butadiene rubber and chloroprene rubber vulcanizates

[0092]

[0093] Application Example 8:

[0094] The rubber compound was prepared according to the formula shown in Table 15, and both 19# and 20# were mixed according to the conventional mixing process.

[0095] Table 15: Basic formula of rubber composite materials containing nitrile rubber and styrene butadiene rubber (parts by mass)

[0096]

[0097] The rubber compound prepared according to the formulation shown in Table 15 was vulcanized at 150°C for 30 min. The properties of the resulting vulcanized rubber are shown in Table 16. As shown in Table 16, antiozonant A2 has a good anti-ozone effect on the nitrile rubber and styrene-butadiene rubber composite material, effectively improving the ozone resistance of the vulcanized rubber, and the anti-ozone effect is good and sustained.

[0098] Table 16: Properties of vulcanizates of nitrile rubber and styrene-butadiene rubber

[0099]

[0100] It can be seen from the above implementation and application examples that the antiozonant containing aromatic amine functional groups and carbon-carbon double bonds provided by the present invention has a good anti-ozone effect on rubber composite materials containing carbon-carbon double bonds in the molecular chain, significantly improves the ozone resistance of vulcanized rubber, and has a good sustained anti-ozone effect.

Claims

1. An application of an antiozonant in ozone protection of rubber materials, characterized in that: The molecular structure of the antiozonant is as follows: ； Among them, R 1 、R 2 、R 3 、R 4 is hydrogen, or is the same or different linear or branched alkyl group having 1 to 8 carbon atoms.

2. The use according to claim 1, characterized in that R 1 、R 2 、R 3 、R 4 The alkyl groups are straight or branched chain alkyl groups of 1 to 3 carbon atoms, which may be the same or different.

3. A rubber comprising a rubber matrix and an additive, characterized in that: The molecular chain of the rubber matrix contains carbon-carbon double bonds, and the additive includes an antiozonant. The molecular structure of the antiozonant is as follows: ； Among them, R 1 、R 2 、R 3 、R 4 is hydrogen, or is the same or different linear or branched alkyl group having 1 to 8 carbon atoms.

4. The rubber according to claim 3, characterized in that R 1 、R 2 、R 3 、R 4 The alkyl groups are straight or branched chain alkyl groups of 1 to 3 carbon atoms, which may be the same or different.

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