Air spring rubber material and preparation method thereof

Abstract

The invention discloses an air spring sizing material and a preparation method thereof, the air spring sizing material is used for preparing an inner rubber layer and an outer rubber layer of an air spring, and the sizing material is mainly composed of the following components in percentage by mass: 25-35% of natural rubber; 20%-30% of butadiene rubber; 5%-15% of trans-butadiene-isoprene rubber; 15%-30% of carbon black; 2%-5% of a plasticizer; 2%-10% of an anti-aging agent; 2%-6% of an active agent; 0.5%-2% of a vulcanizing agent; and 0.5%-2% of an accelerant. The preparation method comprises the steps of first-stage mixing, rubber discharging, standing, second-stage mixing, rubber discharging, standing, rubber sheet extrusion and forming, and the air spring is prepared through a mold pressing type vulcanizing machine. According to the invention, the trans-butadiene-isoprene rubber is combined to modify the blend rubber of the natural rubber and the butadiene rubber, so that the flexural fatigue life of the rubber material is prolonged, and the service life of the product is prolonged.

Description

Technical Field

[0001] The invention relates to an air spring preparation technology, in particular to a preparation method of using trans-butylene-pentadiene rubber in air spring materials. Background Art

[0002] An air spring is an elastic element that uses the reaction force of the internal compression of a rubber airbag as an elastic restoring force. Air springs have functions such as buffering, vibration reduction, and weight bearing, and are the core components of automobile air suspensions. Compared with coil springs and leaf springs, air springs have the advantages of adjustable height / stiffness, high vibration absorption / noise reduction capabilities, long fatigue life, economy, and light weight. Air springs meet the development needs of lightweight, energy-saving, safety, and comfort for automobiles, and have broad application prospects in the future. From the overall perspective of the air spring industry, there are a large number of manufacturers, a low degree of concentration, and a relatively dispersed market share. The competition in the air spring industry is relatively fierce. How to improve product quality and gain a foothold in the fierce industry competition is a problem faced by many air spring manufacturers. The rubber material of the air spring is an important factor affecting its life. Summary of the invention

[0003] In order to improve the service life of an air spring, the present invention provides an air spring inner and outer layer rubber material and a preparation method thereof. The air spring inner and outer layer rubber material adopts the same formula, the main rubber material of the formula is a blend of natural rubber and cis-butyl rubber, and trans-butylene rubber is added. The rubber material has good process performance, and the finished product has better comprehensive indicators such as mechanical strength, wear resistance, tear resistance, and aging resistance. The addition of trans-butylene rubber can further improve the flex fatigue life of the rubber material, thereby improving the service life of the air spring.

[0004] The technical solution adopted by the present invention is as follows: an air spring rubber material is used to make the inner and outer rubber layers of the air spring, and the raw materials and mass percentages of the rubber material are as follows:

[0005]

[0006]

[0007] For the production of inner and outer layer rubber materials of air springs, the vulcanizing agent generally refers to insoluble sulfur; the activators used are zinc oxide and stearic acid; carbon black is generally selected as N550 or N774 carbon black; the plasticizer is selected as cyclohexane oil VIVATEC 3307; the antioxidants are selected as antioxidant RD, antioxidant 4020 and protective wax; the accelerator is selected as CZ.

[0008] So further:

[0009] The plasticizer is naphthenic oil VIVATEC 3307;

[0010] The vulcanizing agent is insoluble sulfur;

[0011] The accelerator is CZ;

[0012] The active agent is zinc oxide and / or stearic acid, and when they are combined, zinc oxide accounts for 1.5%-4% and stearic acid accounts for 0.5%-2%;

[0013] The antioxidant is antioxidant RD, antioxidant 4020 and / or protective wax;

[0014] The carbon black is N550 and / or N774 carbon black. When the carbon black is composed together, the N550 carbon black accounts for 10%-15% and the N774 carbon black accounts for 5%-15%.

[0015] Insoluble sulfur is the vulcanizing agent for vulcanizing natural rubber and butadiene rubber as the main materials; CZ is the accelerator for vulcanizing natural rubber and butadiene rubber; zinc oxide and stearic acid are both used as activators to improve the activity of the rubber; N550 and N774 carbon black are reinforcing materials for natural rubber and butadiene rubber; cyclohexane oil VIVATEC 3307 is the plasticizer for the rubber; antioxidant RD, antioxidant 4020 and protective wax are used as antioxidants for the rubber.

[0016] Natural rubber and cis-1,4-polybutadiene rubber are the main materials used as the rubber materials of the inner and outer layers of air springs; trans-butadiene rubber is used as a modified material for natural rubber and cis-1,4-polyisoprene. The natural rubber selected by the present invention is SCR5 standard rubber. The main components of natural rubber are cis-1,4-polyisoprene and rubber hydrocarbons accounting for 91% to 94%, and the rest are a small amount of non-rubber substances such as protein, fatty acid, ash, sugar, etc., with the characteristics of high mechanical strength, good elasticity, flexural resistance, electrical insulation, etc. Cis-1,4-polybutadiene rubber is the abbreviation of cis-1,4-polybutadiene rubber. It is polymerized from butadiene, and its cis structure content is more than 95%. It has the characteristics of high elasticity, good wear resistance, good cold resistance, low heat generation, flexural resistance and good dynamic performance. Trans-butadiene rubber is a new functional rubber material with excellent performance. It can solve the compatibility problems of general-purpose rubbers such as natural rubber, cis-1,4-polybutadiene rubber, styrene-butadiene rubber, improve the dispersibility of fillers in mixed rubber, and give full play to the excellent performance of each type of rubber. The compound rubber containing trans-butylene rubber has high Green Strength and good dimensional stability; the vulcanized rubber containing trans-butylene rubber has excellent fatigue resistance and wear resistance, low rolling resistance and heat generation. The three are modified and blended in a certain proportion, which can steadily improve the performance of the rubber while ensuring the performance of the rubber.

[0017] The present invention also provides a method for preparing the rubber materials for the inner and outer layers of an air spring, which includes first-stage rubber mixing and second-stage rubber mixing. The method is characterized in that in the first-stage rubber mixing stage, after natural rubber, cis-1,4-butadiene rubber and trans-1,4-butadiene rubber are first added for mixing, an antioxidant, an activator, carbon black and a plasticizer are added in sequence; in the second-stage rubber mixing stage, a vulcanizer and an accelerator are added.

[0018] The above-mentioned preparation method specifically comprises the following steps:

[0019] 1) One-stage rubber mixing

[0020] S1, mixing a certain mass percentage of natural rubber, cis-1,4-butadiene rubber and trans-1,4-butadiene rubber using a 410-liter internal mixer for 20-50 seconds;

[0021] S2, adding a certain mass percentage of antioxidant, activator and carbon black materials to the natural rubber, cis-1,4-butadiene rubber and trans-1,4-butadiene rubber mixed in step S1 and continuing to mix for 30-50 seconds;

[0022] S3, adding a certain mass percentage of plasticizer on the basis of steps S1 and S2 and continuing to mix, the mixing time is 40-60 seconds;

[0023] S4, on the basis of step S3, continue mixing after lifting the ball, the mixing time is 30-50 seconds;

[0024] 2) One section of glue

[0025] The mixed rubber is discharged at a temperature of 145-155°C.

[0026] 3) One section of glue is parked

[0027] Leave a section of discharged glue for 24 hours;

[0028] 4) Second stage rubber mixing

[0029] After the first rubber is parked for 24 hours, a certain mass percentage of vulcanizing agent and accelerator are added to carry out second-stage mixing, and the mixing time is 3-5 minutes;

[0030] 5) Second stage glue removal

[0031] The second stage rubber after mixing in step 4) is subjected to degumming at a degumming temperature of 85-95°C;

[0032] 6) Second stage glue parking

[0033] Leave the glue discharged from the second stage for 24 hours;

[0034] 7) Extrusion film

[0035] The second-stage rubber that has been parked for 24 hours is pressed into a film of required thickness using a film pressing production line, and the temperature of the exit mold of the extruded film is controlled at 80-90°C for molding.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows: the tensile properties, elongation, hardness and other basic properties of the original natural rubber and cis-1,4-butadiene rubber blend modified by trans-butylene-pentadiene rubber can be maintained at the original high level, and the flexural fatigue life is significantly improved. The blended rubber is applied to air spring products, and the fatigue life of the product is improved by 10%-15% compared with the performance of the previous rubber product not modified by trans-butylene-pentadiene rubber, and the process performance of the product during the production process is basically the same. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with the embodiments. However, those skilled in the art should know that the following embodiments are not the only limitations on the technical solutions of the present invention, and any equivalent changes or modifications made under the spirit of the technical solutions of the present invention should be deemed to belong to the protection scope of the present invention.

[0038] This embodiment provides a rubber material for making an air spring, and the specific components and mass percentages are:

[0039]

[0040]

[0041] The rubber compound of the above composition is prepared:

[0042] 1) One-stage rubber mixing

[0043] The mixing steps are as follows:

[0044] S1, 30% by mass of SCR5 standard rubber, 25% of cis-1,4-butadiene rubber and 10% of trans-1,4-butadiene rubber are mixed in a 410-liter internal mixer for 20-50 seconds;

[0045] S2, adding 3.5% antioxidant RD, 0.5% stearic acid, 1.5% zinc oxide, 10% N550 carbon black, and 15% N774 carbon black to the natural rubber, cis-1,4-butadiene rubber and trans-1,4-butadiene rubber mixed in step S1, and continuing to mix for 30-50 seconds;

[0046] S3, adding 2.7% of naphthenic oil VIVATEC 3307 on the basis of S1 and S2 and continuing to mix, the mixing time is 40-60 seconds;

[0047] S4, on the basis of step S3, continue mixing after lifting the ball, the mixing time is 30-50 seconds;

[0048] 2) One section of glue

[0049] The mixed rubber is discharged at a temperature of 145-155°C.

[0050] 3) One section of glue is parked

[0051] Leave the mixed rubber for 24 hours;

[0052] 4) Second stage rubber mixing

[0053] After 24 hours of storage, add 1.2% insoluble sulfur and 0.6% accelerator CZ to the first stage of rubber for two-stage mixing, and the mixing time is 3-5 minutes;

[0054] 5) Second stage glue removal

[0055] The mixed second stage rubber is discharged at a temperature of 85-95°C; the properties of the semi-finished rubber are tested;

[0056] 6) Second stage glue parking

[0057] Leave the glue discharged from the second stage for 24 hours;

[0058] 7) Press out the film

[0059] After being parked for 24 hours, the second-stage rubber is pressed out into a film of required thickness using a film pressing production line, and the temperature of the extruded film outlet is controlled at 80-90℃;

[0060] 8) Molding

[0061] The film and the cord with a certain angle are laminated on the forming roller in a set order, and the semi-finished tire tube is formed by wrapping the wire rings at both ends;

[0062] 9) Vulcanization molding

[0063] The molded tire tube is prepared into an air spring using a compression vulcanizer. The vulcanization temperature is 150-160℃ and the vulcanization mold pressure is 160-180kgf / cm 2 .

[0064] The performance of the finished air spring was tested and compared with the rubber compound made of only natural rubber and butadiene rubber, its performance parameters such as stiffness, bursting pressure, and fatigue performance were significantly improved.

[0065]

[0066]

[0067] It can be seen that the tensile properties, elongation and other properties of the blended rubber modified with trans-butylene rubber and cis-butadiene rubber are slightly lower than before the modification, but its level 6 flexural fatigue life is increased by 50,000 times compared with before, and the number of bench fatigue tests on the product is increased by 10% compared with before the modification.

Claims

1. An air spring rubber material, characterized in that: The following components are included in mass percentage: Natural rubber 25%-35%; Butadiene rubber 20%-30%; Trans-butylene rubber 5%-15%; Carbon black 15%-30%; Plasticizer 2%-5%; Antiaging agent 2%-10%; Active agent 2%-6%; Vulcanizing agent 0.5%-2%; Accelerator 0.5%-2%.

2. The air spring rubber material according to claim 1, characterized in that: The plasticizer is naphthenic oil VIVATEC 3307; The vulcanizing agent is insoluble sulfur; The accelerator is CZ; The active agent is zinc oxide and / or stearic acid; The antioxidant is one or a combination of antioxidant RD, antioxidant 4020, and protective wax; The carbon black is N550 carbon black and / or N774 carbon black.

3. The air spring rubber material according to claim 1 or 2, characterized in that: The natural rubber is SCR5 standard rubber, the main components of which are cis-1,4-polyisoprene and rubber hydrocarbon, accounting for 91% to 94%; The butadiene rubber is a cis-1,4-polybutadiene rubber synthetic rubber, and the cis structure content is above 95%.

4. A method for preparing an air spring rubber material as claimed in any one of claims 1 to 3, comprising a first stage of rubber mixing and a second stage of rubber mixing, wherein in the first stage of rubber mixing, natural rubber, cis-1,4-butadiene rubber and trans-1,4-butadiene rubber are first added for mixing, and then an antioxidant, an activator, carbon black and a plasticizer are added in sequence; and in the second stage of rubber mixing, a vulcanizing agent and an accelerator are added.

5. The preparation method according to claim 4, characterized in that The specific steps include: 1) One-stage rubber mixing S1, mixing a certain mass percentage of natural rubber, cis-1,4-butadiene rubber and trans-1,4-butadiene rubber using a 410 liter internal mixer for 20-50 seconds; S2. Add a certain mass percentage of antioxidant, activator and carbon black material to the natural rubber, cis-1,4-butadiene rubber and trans-1,4-butadiene rubber mixed in step S1 and continue mixing for 30-50 seconds; S3. Add a certain mass percentage of plasticizer based on steps S1 and S2 and continue mixing for 40-60 seconds; S4, after lifting the ball on the basis of step S3, continue mixing, the mixing time is 30-50 seconds; 2) One section of glue After mixing, the rubber is discharged at a temperature of 145-155℃. 3) One section of glue is parked Leave a section of discharged glue for 24 hours; 4) Second stage rubber mixing After the rubber has been stored for 24 hours, a certain mass percentage of vulcanizing agent and accelerator is added to the first stage of rubber for two-stage mixing, and the mixing time is 3-5 minutes; 5) Second stage glue removal The second stage rubber after mixing in step 4) is subjected to debinding at a debinding temperature of 85-95°C; 6) Second stage glue parking Leave the glue discharged from the second stage for 24 hours; 7) Extrusion film The second-stage rubber that has been parked for 24 hours is pressed into a film of the required thickness using a film pressing production line, and the temperature of the extruded film outlet is controlled at 80-90°C.

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