Method for improving bonding fastness of aramid fiber rope

Abstract

The invention discloses a method for improving the bonding fastness of an aramid fiber rope, which comprises the following steps: S1, after secondarily twisted aramid fiber passes through a first drafting unit by a yarn storage frame, dipping the aramid fiber in a bath glue solution, and then passing through a drying oven H1 of 100-130 DEG C; s2, after coming out of the drying oven H1, sequentially passing through a second drafting unit, two-bath glue solution dipping and a drying oven H2 with the temperature of 180-200 DEG C; and S3, after being discharged from the drying oven H2, sequentially passing through a drying oven H3 at the temperature of 200-240 DEG C, a fourth drafting unit, three-bath glue dipping, a drying oven H4 at the temperature of 120-180 DEG C and a fifth drafting unit, and finally entering a winding machine. Through the multi-step and multi-factor synergistic treatment method, the bonding fastness of the aramid fiber rope and the rubber is successfully improved, and remarkable effects are achieved in the aspects of adhesive force, glue scraping and the like.

Description

Technical Field

[0001] The invention relates to a method for improving the bonding strength of an aramid cord, and belongs to the technical field of aramid cords. Background Art

[0002] The fiber skeleton material for tape plays a decisive role in providing sufficient strength for rubber products and maintaining their dimensional stability. The development direction of domestic tape products is high performance, lightweight, energy saving, environmental protection, and long life. my country's tape industry continues to eliminate low-strength skeleton materials. Polyester cords have the advantages of high strength, large modulus, impact resistance, good dimensional precision and stability, and low cost, but have low adhesion to rubber. In recent years, through the optimization of dipping formulas and processes, the requirements of tape performance can be basically met, and the pace of polyesterification of skeleton materials and structural cords has been accelerated. Some higher-performance tapes have begun to use aramid cords as skeleton materials, focusing on improving impact resistance, tear resistance, wear resistance and other properties, and their output and quality have been improved simultaneously.

[0003] At present, the proportion of high-performance tapes in developed countries has reached 80%, and the proportion of high-performance tape products in my country accounts for about 60% of the national tape production. Therefore, increasing the proportion of high-performance tape products is the development trend of my country's tape industry. The consumption of aramid in the pipe and belt industry in Europe and the United States is more than ten times that of the tire industry. Special-purpose tapes or large V-belts mostly use aramid cords. In my country, the key technologies of twisting, weaving, and dipping of aramid fibers are developed, and the high-performance skeleton materials are developed, which have broad application prospects.

[0004] The chemical inertness and smooth surface of aramid result in poor adhesion between it and rubber. It is necessary to improve the bonding strength between the fiber and rubber through surface modification and dipping processing technology of aramid. However, the bonding strength between aramid fabric and rubber after processing by traditional dipping technology is low. The dipping formula and production process of aramid cord need further research and development. Summary of the invention

[0005] Based on the above, the present invention provides a method for improving the bonding strength of aramid cords to solve the technical problem of poor bonding between aramid fibers and rubber.

[0006] The technical solution of the present invention is: a method for improving the bonding strength of aramid cords, comprising:

[0007] After the re-twisted aramid fiber S1 passes through the first drafting unit from the yarn storage rack, is impregnated with a bath of adhesive, and then passes through an oven H1 at 100-130°C;

[0008] After S2 comes out of the oven H1, it passes through the second drawing unit, the second bath glue solution impregnation and the oven H2 at 180-200°C;

[0009] After coming out of the oven H2, S3 passes through the third drawing unit, the oven H3 at 200-240°C, the fourth drawing unit, three-bath glue dipping, the oven H4 at 120-180°C and the fifth drawing unit in sequence, and finally enters the winding machine.

[0010] Preferably, the first-bath glue solution is a mixture of toluene and isocyanate, wherein the proportion of isocyanate is 1-20%. Preferably, the isocyanate is dimethyl toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI) or hexamethylene diisocyanate (HDI).

[0011] Preferably, the second-bath glue solution is a mixture of RFL glue solution and trimethylolphenol, wherein the proportion of the RFL glue solution is 10-40%.

[0012] Preferably, the RFL glue is an adhesive system composed of resin, formaldehyde and latex.

[0013] Preferably, the resin is an epoxy resin, and the latex is butylpyrrolidone latex.

[0014] Preferably, the three-bath glue solution is a mixture of natural rubber latex and polyether polyamine, wherein the content of natural rubber latex is 20-50%.

[0015] Preferably, the polyether polyamine is polyethylene glycol amine, polypropylene glycol amine, polyether amine stearate or polyether amine epoxy resin.

[0016] Preferably, the speed of the aramid fiber is 35 m / min, and the air volume of the ovens H1 to H4 is 30-50%.

[0017] Beneficial effects of the present invention: The present invention uses multiple dipping treatments, each time using different formulations of glue, to gradually improve the surface properties of aramid fibers; uses ovens with different temperatures at different stages to ensure that the glue is fully solidified and the fiber properties are stable; uses multiple drafting units to ensure that the fiber maintains appropriate tension during the dipping and drying process, which is conducive to the uniform distribution and adhesion of the glue; and uses different dipping formulations at different stages to improve the surface properties of aramid fibers in a targeted manner. The present invention successfully improves the bonding strength between aramid cords and rubber through this multi-step, multi-factor synergistic treatment method, and achieves significant effects in terms of adhesion and scraping glue.

[0018] In the present invention, a bath of glue is formed by mixing toluene and isocyanate, and the blocked isocyanate is unblocked at a certain temperature, reacting with the amino group on the fiber surface to form a chemical bond, thereby increasing the polar functional groups on the fiber surface. The second bath of glue is formed by mixing RFL glue and trimethylolphenol. The RFL glue can form a network structure on the fiber surface, increase the surface roughness and chemical activity, and trimethylolphenol can further increase the polar groups on the fiber surface and improve the RFL solution's reaction activity with the fiber. This step significantly improves the bonding ability of the fiber surface. The third bath of glue is formed by mixing natural latex and polyether polyamine. Natural latex provides good interfacial compatibility, while polyether polyamine further enhances the chemical bonding between the fiber and the rubber. High temperature treatment helps these substances to fully react with the fiber surface to form a stable interfacial structure. This step is the key to ultimately improving the bonding strength. Multi-stage temperature-controlled drying ensures that the glue is fully solidified after each dipping, while protecting the performance of the aramid fiber; and multiple stretching treatments ensure that the fiber maintains appropriate tension throughout the process, which is conducive to the uniform distribution and adhesion of the glue, greatly improving the quality stability and bonding strength of the final product. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation of the present invention is described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0020] Example 1

[0021] 1. Glue formula

[0022] One-bath glue solution formula: toluene: 900, diphenylmethane diisocyanate (MDI): 100. Preparation method: first put toluene into the reaction tank, and control the water temperature at 30℃±3℃; then slowly add MDI into the reaction tank and stir for more than 30 minutes.

[0023] Second bath glue formula: RFL glue + trimethylolphenol. The specific formula is as follows: deionized water: 700, epoxy resin: 50, formaldehyde: 100; butylpyrrolidone latex: 100; trimethylolphenol: 50. Preparation method: (1) Add deionized water and formaldehyde to the reactor at once according to the weight parts specified in the formula to prepare a 20% formaldehyde aqueous solution for standby use; (2) Slowly add epoxy resin to the reactor, control the temperature with jacket water, maintain the temperature in the reactor between 22-25°C, and prepare RF glue solution; stir at a speed of 500±50rpm, and react for 1.5 hours; (3) Add deionized water and butylpyrrolidone latex into a preparation tank and stir to prepare a 25% latex solution for standby use; (4) Transfer the RF resin liquid in the reactor where the reaction is completed to the preparation tank, and continue stirring for 0.5 hours to obtain RFL glue solution; (5) Add trihydroxymethylphenol to the preparation tank and stir for 1 hour, then move to an air-conditioned room for aging for 24 hours and send to a dipping machine for standby use.

[0024] Formula of three-bath glue solution: natural rubber latex: 300, polyethylene glycol amine: 700. Preparation method: (1) Add polyethylene glycol amine into the preparation tank according to the weight parts specified in the formula; (2) Slowly add natural rubber latex and stir for 0.5 hours.

[0025] 2. Dipping process

[0026] Yarn storage rack (white yarn after re-twisting) - first drafting unit - one-bath glue dipping - oven H1 - second drafting unit - two-bath glue dipping - oven H2 - third drafting unit - oven H3 - fourth drafting unit - three-bath glue dipping - oven H4 - fifth drafting unit - winding machine. The wire rope is dipped in glue in the glue tank, and the residual slurry is scraped off by scraping with a scraper. The temperature of each oven is as follows:

[0027] H1 temperature: 130℃;

[0028] H2 temperature: 190℃

[0029] H3 temperature: 220℃;

[0030] H4 temperature: 150℃;

[0031] H1-H4 air volume: 40%;

[0032] Process speed: 35m / min.

[0033] Comparative Example 1

[0034] 1. Glue formula

[0035] The formula of the first bath glue solution is: toluene: 900, diphenylmethane diisocyanate (MDI): 100. The preparation method is the same as Example 1.

[0036] Formula of two-bath glue solution: traditional RFL dipping solution, formula: deionized water: 740, caustic soda: 4, resorcinol: 78, formaldehyde: 78; butylpyrrolidone latex: 100. Preparation method: (1) Dissolve sodium hydroxide in deionized water according to the weight parts specified in the formula to prepare a 1% alkaline solution, and add it to the reactor; (2) Slowly add solid resorcinol into the reactor, control the temperature with jacket water, keep the temperature in the reactor between 22-25°C, and prepare RF glue solution; stir at a speed of 500±50rpm, and react for 1.5 hours. (3) Add deionized water and butylpyrrolidone latex into the preparation tank and stir to prepare a 25% latex solution for use; (4) Transfer the RF resin liquid in the reactor to the preparation tank, and continue stirring for 0.5 hours to obtain RFL glue solution; after stirring, move to an air-conditioned room for aging for 24 hours and then send to the dipping machine for use.

[0037] 2. Dipping process

[0038] Yarn storage rack (white yarn after re-twisting) - first drafting unit - one-bath glue dipping - oven H1 - second drafting unit - two-bath RFL glue dipping - oven H2 - third drafting unit - oven H3 - fourth drafting unit - winding machine. The wire rope is dipped in glue in the glue tank, and the residual slurry is scraped off by scraping with a scraper. The temperature of each oven is as follows:

[0039] H1 temperature: 130℃;

[0040] H2 temperature: 200℃;

[0041] H3 temperature: 180℃;

[0042] H1-H3 air volume: 40%;

[0043] Process speed: 16m / min.

[0044] Comparative Example 2

[0045] Except for the drawing speed and the oven temperature, the rest is the same as in Example 1.

[0046] H1 temperature: 100℃;

[0047] H2 temperature: 150℃;

[0048] H3 temperature: 280℃;

[0049] H4 temperature: 110℃;

[0050] H1-H4 air volume: 40%;

[0051] Process speed: 16m / min.

[0052] Comparative Example 3

[0053] Except for the three-bath glue solution formula, the rest is the same as Example 1.

[0054] Formula of three-bath glue solution: natural rubber latex: 300, toluene: 700. Preparation method: (1) Add toluene into the preparation tank according to the weight parts specified in the formula; (2) Slowly add natural rubber latex and stir for 0.5 hours.

[0055] Comparative Example 4

[0056] Except for the second bath glue solution formula, the rest is the same as Example 1.

[0057] Second bath glue liquid formula: RFL glue liquid. The RFL glue liquid formula is as follows: deionized water: 700, epoxy resin: 100, formaldehyde: 100; butylpyrrolidone latex: 100. Preparation method: (1) Add deionized water and formaldehyde to the reactor at once according to the weight parts specified in the formula to prepare a 20% formaldehyde aqueous solution; (2) Slowly add epoxy resin to the reactor, control the temperature with jacket water, and keep the temperature in the reactor between 22-25°C to prepare RF glue liquid; stir at a speed of 500±50rpm and react for 1.5 hours; (3) Add deionized water and butylpyrrolidone latex to the preparation tank and stir to prepare a 25% latex solution for use; (4) Transfer the RF resin liquid in the reactor that has completed the reaction to the preparation tank, and continue stirring for 0.5 hours to obtain RFL glue liquid. (5) After stirring, move to an air-conditioned room for aging for 72 hours and then send to the dipping machine for use.

[0058] Example 2

[0059] Except for the three-bath glue solution formula, the rest is the same as Example 1.

[0060] Formula of three-bath glue solution: natural rubber latex: 300, polyetheramine epoxy resin: 700. Preparation method: (1) Add polyetheramine epoxy resin into the preparation tank according to the weight parts specified in the formula; (2) Slowly add natural rubber latex and stir for 0.5 hours.

[0061] Example 3

[0062] Except for the one-bath glue solution formula, the rest is the same as Example 1.

[0063] One-bath glue solution formula: toluene: 900, hexamethylene diisocyanate (HDI): 100. Preparation method: first put toluene into the reaction tank, and control the water temperature at 30℃±3℃; then slowly add HDI into the reaction tank and stir for more than 30 minutes.

[0064] Example 4

[0065] Except for the three-bath glue solution formula, the rest is the same as Example 1.

[0066] Formula of three-bath glue solution: natural rubber latex: 200, polyetheramine epoxy resin: 800. Preparation method: (1) Add polyetheramine epoxy resin into the preparation tank according to the weight parts specified in the formula; (2) Slowly add natural rubber latex and stir for 0.5 hours.

[0067] The test used the same sample of 2×5 aramid strands, and carried out the dipping process according to the processes of Examples 1 to 5 and Comparative Examples 1 to 3, and tested the breaking strength, breaking elongation and T-extraction force. Test method: The performance tests of breaking strength and breaking elongation were carried out on an Instron 3365 tensile testing machine. The tensile method was based on GB / T32108---201, and the T-extraction was tested according to the national standard GB / T31333-2014 method. The results are shown in Table 1:

[0068] Table 1 Test results of 2×5 aramid strands

[0069]

[0070] It can be seen from Table 1 that: 1. Compared with Comparative Example 1, the present invention improves the roughness of the surface of the cord by adding three dipping solutions, improves the adhesion between the fiber and the rubber, and makes it easier for customers to apply glue when scraping the glue. 2. Compared with Comparative Example 2, during the dipping process of the present invention, by adjusting the dipping temperature, drawing speed and other process parameters, the performance of the dipped cord can be improved, and the product index quality and dipping efficiency can be improved. 3. Compared with Comparative Example 3, by adjusting the formula design in the three dipping solutions, the adhesive system composed of latex and polyether polyamine can achieve good adhesion between the cord and the rubber, and the T extraction force value can be significantly improved.

[0071] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for improving the bonding strength of aramid cords, characterized in that: include: After the re-twisted aramid fiber S1 passes through the first drafting unit from the yarn storage rack, is impregnated with a bath of adhesive, and then passes through an oven H1 at 100-130°C; After S2 comes out of the oven H1, it passes through the second drawing unit, the second bath glue solution impregnation and the oven H2 at 180-200°C; After coming out of the oven H2, S3 passes through the third drawing unit, the oven H3 at 200-240°C, the fourth drawing unit, three-bath glue dipping, the oven H4 at 120-180°C and the fifth drawing unit in sequence, and finally enters the winding machine.

2. The method for improving the bonding strength of aramid cord according to claim 1, characterized in that: The one-bath glue solution is prepared by mixing toluene and isocyanate, wherein the proportion of isocyanate is 1-20%.

3. The method for improving the bonding strength of aramid cord according to claim 2, characterized in that: The isocyanate is dimethyl toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate or hexamethylene diisocyanate.

4. The method for improving the bonding strength of aramid cord according to claim 1, characterized in that: The second-bath glue solution is formed by mixing RFL glue solution and trimethylolphenol, wherein the proportion of the RFL glue solution is 10-40%.

5. The method for improving the bonding strength of aramid cord according to claim 4, characterized in that: The RFL glue is a bonding system composed of resin, formaldehyde and latex.

6. The method for improving the bonding strength of aramid cord according to claim 5, characterized in that: The resin is epoxy resin, and the latex is butylpyrrolidone latex.

7. The method for improving the bonding strength of aramid cord according to claim 1, characterized in that: The three-bath glue solution is prepared by mixing natural rubber latex and polyether polyamine, wherein the content of natural rubber latex is 20-50%.

8. The method for improving the bonding strength of aramid cord according to claim 7, characterized in that: The polyether polyamine is polyethylene glycol amine, polypropylene glycol amine, polyether amine stearate or polyether amine epoxy resin.

9. The method for improving the bonding strength of aramid cord according to claim 1, characterized in that: The speed of the aramid fiber is 35 m / min, and the air volume of the ovens H1 to H4 is 30-50%.

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