A process control method for realizing no blooming of steel cord

Abstract

The application provides a process control method for realizing no blooming of steel cord, sampling a rubber compound for steel cord calendering at a raw rubber stage, determining free sulfur content in the rubber compound, and calculating conversion rate of insoluble sulfur of the rubber compound based on a determination result; calling a preset first threshold value and comparing the calculated conversion rate of insoluble sulfur; and when the calculated conversion rate of insoluble sulfur is greater than the first threshold value, outputting a result that the rubber compound is unqualified. The process control method for realizing no blooming of steel cord solves the technical problem that steel cord cannot be effectively prevented from blooming in the related art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tire manufacturing, in particular to a process control method for realizing no blooming of steel cord. BACKGROUND

[0002] In the rubber tire industry, steel cord calendering is a very important manufacturing technology, and the quality of the steel cord directly determines the performance of the tire framework material, and thus the performance of the finished tire. Among them, the blooming of the steel cord is a common quality defect.

[0003] Nowadays, the control technology in the industry generally considers the mixing process of the rubber compound, the rubber temperature in each area of the calendering, etc., and when blooming defects occur, the analysis is traced back and improved, at this time, serious economic losses and quality risks have been caused. Free sulfur is soluble in sulfur, but the solubility in rubber is about 1%, which is slightly different for different rubber systems. When the content exceeds the solubility, part of the ordinary free sulfur will precipitate to the surface after the rubber is cooled, which is "blooming". The existing technology prevents "blooming" by converting the insoluble sulfur in the rubber compound at the best temperature of 105℃, so the discharge temperature of the rubber compound and the calendering rubber temperature are controlled below 105℃. Although setting the best temperature can further prevent blooming, the conversion rate of insoluble sulfur in the mixed rubber is not only related to the temperature, but also changes with time and mass fraction ratio. Therefore, the blooming cannot be fundamentally solved.

[0004] Therefore, the prior art needs to be further developed. SUMMARY

[0005] The present application aims to overcome the above technical deficiencies, and provides a process control method for realizing no blooming of steel cord, to solve the technical problem that the steel cord cannot be effectively prevented from blooming in the related art.

[0006] To achieve the above technical purpose, the present application adopts the following technical scheme: a process control method for realizing no blooming of steel cord is provided, the rubber compound for steel cord calendering is sampled at the original rubber stage, the free sulfur content in the rubber compound is determined, and the conversion rate of insoluble sulfur in the rubber compound is calculated based on the determination result; the first threshold value is called and compared with the calculated conversion rate of insoluble sulfur; when the calculated conversion rate of insoluble sulfur is greater than the first threshold value, the result that the rubber compound is unqualified is output.

[0007] Further, the first threshold value is 14.5%.

[0008] Further, the first threshold value is preset.

[0009] Further, the first threshold is calculated by the following method: a correspondence relationship between the conversion rate of the insoluble sulfur of the rubber compound for steel cord calendering and the blooming condition is established in advance; the second threshold for realizing complete non-blooming of the steel cord in the rubber compound supplying stage is determined based on the correspondence relationship; and the first threshold is calculated based on the development relationship of the conversion rate of the insoluble sulfur of the rubber compound in each stage of the steel cord calendering by using the second threshold.

[0010] Further, the second threshold is 20%.

[0011] Further, the growth rates of the conversion rate of the insoluble sulfur of the rubber compound in the steel cord calendering stages are a first growth rate, a second growth rate and a third growth rate in sequence.

[0012] Further, the calculation formula of the first threshold is: the first threshold = the second threshold - (the first growth rate + the second growth rate + the third growth rate).

[0013] Further, the free sulfur content in the rubber compound is determined by using a physical separation technology.

[0014] Further, the calculation formula of the conversion rate of the insoluble sulfur of the rubber compound is: the conversion rate of the insoluble sulfur = the free sulfur content / the mass fraction of the insoluble sulfur * 100%, wherein the mass fraction of the insoluble sulfur is obtained from a formula table of the rubber compound.

[0015] Further, when the calculated conversion rate of the insoluble sulfur is less than or equal to the first threshold, the steel cord calendering process is continuously executed.

[0016] Beneficial effects:

[0017] 1. The control method for preventing the steel cord from blooming adopted in the present application calculates the mass fraction of the insoluble sulfur by quantitatively testing the relationship among the conversion rate of the insoluble sulfur, the temperature and the time, thereby judging the quality of the rubber compound and solving the problem of the steel cord blooming from the source, and economic loss is avoided.

[0018] 2. The control method for preventing the steel cord from blooming adopted in the present application changes from a passive remedial control mode after the blooming occurs to an active precise control mode for predicting the blooming, thereby improving the product quality of the steel cord.

[0019] 3. The control method for preventing the steel cord from blooming adopted in the present application greatly reduces the occurrence frequency of the steel cord blooming, reduces the cost damage and improves the product production qualification rate. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a flow chart of the process control method for preventing the steel cord from blooming adopted in the embodiment of the present application;

[0021] Figure 2is a device connection diagram of a steel cord calendering process adopted by the embodiment of the present application;

[0022] Figure 3 is a conversion process schematic diagram of insoluble sulfur in the rubber compound into free sulfur adopted by the embodiment of the present application.

[0023] Among them, the above-mentioned drawings include the following reference signs:

[0024] 1, extruder; 2, refiner; 3, rubber supply machine; 4, conveying belt. DETAILED DESCRIPTION

[0025] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0026] According to the embodiment of the present application, a process control method for realizing no blooming of steel cord is provided, which comprises: S100, sampling the rubber compound for steel cord calendering at the raw rubber stage, determining the free sulfur content in the rubber compound, and calculating the conversion rate of insoluble sulfur in the rubber compound based on the determination result; S200, comparing the preset first threshold value with the calculated conversion rate of insoluble sulfur; S300, when the calculated conversion rate of insoluble sulfur is greater than the first threshold value, outputting the result that the rubber compound is unqualified. Through the above process control method, the blooming of steel cord is effectively prevented.

[0027] Blooming refers to the phenomenon that the sulfur, wax, accelerant, antioxidant, plasticizer and filler and other compounding agents in the rubber product migrate from the inside of the rubber compound or product to the surface and precipitate substances such as frost. The essential reason is that the amount of these compounding agents exceeds the solubility in the rubber compound or vulcanized rubber, resulting in the transition from metastable state to stable state. The blooming of steel cord is mainly caused by the precipitation of sulfur, also known as blooming of sulfur. In order to avoid such situations, insoluble sulfur is used instead of ordinary sulfur in the formula.

[0028] The solubility of sulfur in different rubbers is different, and the solubility in CR, BR, SBR and NR is higher, while the solubility in saturated rubbers such as EPDM, IIR and CIIR is lower, and the mass fraction of insoluble sulfur is also different in different rubber formulations. The present application evaluates the blooming characteristics of the rubber by using the insoluble sulfur conversion rate, when the insoluble sulfur conversion rate is high, the free sulfur content in the rubber exceeds the solubility of sulfur in the rubber, and then precipitates on the surface of the steel cord, thereby forming blooming; when the insoluble sulfur conversion rate is low, it is not easy to form blooming. Therefore, the process control method for realizing no blooming of steel cord in the present application effectively prevents the steel cord from blooming.

[0029] In the process control method for realizing no blooming of steel cord in the present embodiment, the first threshold value is set to 14.5%, and the first threshold value is calculated by the following method: a corresponding relationship between the insoluble sulfur conversion rate of the rubber for steel cord calendering in the feeding stage and the blooming condition is established in advance; the second threshold value for realizing complete no blooming of steel cord in the feeding stage is determined based on the corresponding relationship; and the first threshold value is calculated based on the development relationship of the insoluble sulfur conversion rate of the rubber in each stage of the steel cord calendering by using the second threshold value.

[0030] Referring to Figure 1 and Figure 2 , the raw rubber is extruded by the extruder 1 to form a rubber egg with a certain plasticizing effect; then it is further plasticized by the refining machine 2, and is conveyed to the rubber feeder 3 by the conveying belt 4, and is plasticized and sheared for a certain time on the rubber feeder 3, so that the rubber is more uniform, and then is conveyed to the calender for rubber coating operation. In this process, the rubber is subjected to certain shearing and plasticizing, and the stability of the insoluble sulfur in the rubber becomes worse and worse, and when the insoluble sulfur conversion rate of the rubber rises to a certain value, that is, the second threshold value, the steel cord will bloom.

[0031] Referring to Figure 1 , in the process control method for realizing no blooming of steel cord in the present embodiment, the second threshold value is 20%. The steel cord calendering process includes a raw material stage, an extrusion stage using the extruder 1, a refining stage using the refining machine 2, and a feeding stage using the rubber feeder 3, and multiple samples are taken from the raw material stage, the extrusion stage, the refining stage and the feeding stage respectively; the insoluble sulfur conversion rate C1 of the raw material stage, the insoluble sulfur conversion rate C2 of the extrusion stage, the insoluble sulfur conversion rate C3 of the refining stage and the insoluble sulfur conversion rate C4 of the feeding stage are obtained.

[0032] By setting multiple groups of experiments, the relationship between the insoluble sulfur conversion rate and the blooming in the raw material stage, the extrusion stage, the refining stage and the feeding stage under the same feeding process conditions is measured.

[0033] Table 1 Relationship between insoluble sulfur conversion rate and blooming (unit: %)

[0034]

[0035] From the test data in Table 1, it can be concluded that whether the steel cord is bloomed or not has a significant relationship with the conversion rate of insoluble sulfur in the rubber compound. When the conversion rate of insoluble sulfur is 21.45% or above at the feeding stage, the steel cord is bloomed, and the more the conversion rate of insoluble sulfur increases, the more serious the blooming of the steel cord. On the contrary, when the conversion rate of insoluble sulfur is 17.5% or below, the steel cord is not bloomed. After a large number of positive tests, when the conversion rate of insoluble sulfur in the rubber compound is less than 20%, the steel cord is not bloomed, thereby determining the second threshold value as 20%.

[0036] The feeding process conditions at the raw material stage, the extrusion stage, the refining stage, and the feeding stage include the discharge temperature and the extrusion pressure of the extruder 1. The screw diameter of the extruder is 250 mm, and its specific function is to fully plasticize the rubber compound and achieve a rubber compound with good fluidity, so as to be fully extruded and formed. The main control points are the discharge temperature and the extrusion pressure of the extruder 1. In order to ensure the overall feeding amount, two extruders 1 are used to feed at the same time (as shown in FIG. 1). Figure 1

[0037] The feeding process conditions also include setting the refining temperature, the roller spacing, the roller speed, and the rubber accumulation height of the refiner 2. The roller diameter of the refiner 2 is 550 mm, and its specific function is to crush the extruded rubber compound and further plasticize the rubber compound to improve the plasticization uniformity of the rubber compound.

[0038] The feeding process conditions also include setting the feeding temperature, the roller spacing, the roller speed, the rubber accumulation height, and the feeding width of the feeding machine 3. The roller diameter of the feeding machine 3 is 550 mm, and its specific function is to further plasticize the rubber compound to improve the plasticization uniformity of the rubber compound and supply the rubber compound to the calender.

[0039] The discharge temperature and the refining temperature are both 85-100°C, and the feeding temperature is 90-105°C. The insoluble sulfur in the rubber compound is crystallized and converted into soluble sulfur for a long time under the heat. Therefore, the temperature is controlled below 105°C to reduce the probability of blooming due to temperature factors.

[0040] The extruder feeding process parameters during the experiment (unit: °C):

[0041] Difference Screw temperature Plasticizing temperature Extrusion temperature Discharge temperature Extruder 70℃ 65℃ 75℃ 85-100℃

[0042] The refiner and feeding machine feeding process parameters during the experiment:

[0043] Difference Roll temperature Roll gap Speed ratio Supply temperature Refiner 60℃ 10 mm 1.24 85-100℃ Supply machine 60℃ 10 mm 1.24 90-105℃

[0044] ​After a large number of positive experiments, when the insoluble sulfur conversion rate in the compound reaches 20%, that is, the free sulfur content in the compound is 0.588%, the free sulfur content in the compound reaches the maximum solubility of free sulfur in this compound, that is, the critical value of the steel cord spraying in the rubber supply stage is the second threshold value of the insoluble sulfur conversion rate of 20%.

[0045] When the second threshold value C4 of the insoluble sulfur conversion rate of the rubber in the rubber supply stage is ≤20%, the steel cord will not spray within a certain time; when the second threshold value C4 of the insoluble sulfur conversion rate is >20%, the steel cord will spray.

[0046] In the process control method for realizing no spraying of the steel cord in the embodiment, the growth rates of the insoluble sulfur conversion rate of the compound in the steel cord calendering stage are the first growth rate, the second growth rate and the third growth rate in turn. If the insoluble sulfur conversion rate exceeds 20% in the rubber supply stage, spraying will occur. If the insoluble sulfur conversion rate in the raw material stage is obtained, spraying can be effectively avoided from the source. Further research shows the change of the insoluble sulfur conversion rate of the compound after the compound passes through the steel cord calendering and rubber supply system.

[0047] Table 2: Increase value of insoluble sulfur conversion rate (unit: %)

[0048]

[0049] As shown in Table 2, the first growth rate of the insoluble sulfur conversion rate of the entire steel cord calendering and rubber supply system from the raw material stage to the extrusion stage is 1.616%, the second growth rate of the insoluble sulfur conversion rate from the extrusion stage to the refining stage is 1.908%, the third growth rate of the insoluble sulfur conversion rate from the refining stage to the rubber supply stage is 1.958%, and the average increase of the insoluble sulfur conversion rate from the raw material stage to the rubber supply stage is 5.482%.

[0050] In the process control method for realizing no spraying of the steel cord in the embodiment, the calculation formula of the first threshold value is: first threshold value = second threshold value - (first growth rate + second growth rate + third growth rate). The insoluble sulfur conversion rate in the compound gradually increases with the rubber supply process, and the first threshold value of the insoluble sulfur conversion rate in the raw material is 14.5% through the second threshold value of the insoluble sulfur conversion rate of 20% in the rubber supply stage and the increase value of the insoluble sulfur conversion rate from the raw material stage to the rubber supply stage.

[0051] In the process control method for realizing the non-bloom of steel cord in the embodiment, the free sulfur content in the rubber compound is measured by using the physical separation technology. The principle is that after the free sulfur is dissolved out by using an organic solvent, the liquid phase method is used to separate the free sulfur from other substances according to the difference in the movement speed of the components in the mobile phase after multiple adsorption-desorption, and the difference in the distribution coefficient of the components in the mobile phase. The same mobile phase, the retention time of the substance is certain, and the free sulfur is qualitatively determined according to the standard curve and the peak area to determine the content of the free sulfur.

[0052] In the process control method for realizing the non-bloom of steel cord in the embodiment, the conversion rate of the insoluble sulfur in the rubber compound is calculated by the formula: conversion rate of insoluble sulfur = free sulfur content / mass fraction of insoluble sulfur * 100%, wherein the mass fraction of insoluble sulfur is obtained from the formula table of the rubber compound.

[0053] According to the formula table of the rubber compound, the mass fraction of the insoluble sulfur in the rubber compound can be easily obtained, and the content of the insoluble sulfur converted into ordinary sulfur can be measured by experiments, so that the conversion rate of the insoluble sulfur can be obtained.

[0054] In the process control method for realizing the non-bloom of steel cord in the embodiment, when the calculated conversion rate of the insoluble sulfur is less than or equal to the first threshold value, the steel cord calendering process is continued.

[0055] Process control method for realizing the non-bloom of steel cord

[0056] 1. Sampling at the raw rubber stage, the sample size is 10cm*10cm;

[0057] 2. Sending to the laboratory to measure the content A of free sulfur in the rubber compound by using the liquid phase method HPLC;

[0058] 3. Checking the formula table of the rubber compound to obtain the mass fraction B of insoluble sulfur in the rubber compound;

[0059] 4. Calculating the conversion rate C of the insoluble sulfur in the rubber compound = A / B*100%;

[0060] 5. When the first threshold value C1 of the conversion rate of the insoluble sulfur is less than or equal to 14.5%, the steel cord will not bloom, and the steel cord calendering process is continued; when the first threshold value C1 is greater than 14.5%, the steel cord blooms, and the raw rubber sample is unqualified, and the steel cord calendering process is stopped.

[0061] It should be noted that the terms "first", "second" and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the use of these terms is interchangeable under appropriate circumstances such that the descriptive

[0062] Optionally, the specific examples in the embodiments can refer to the examples described in the above embodiments, and the embodiments will not be described here again.

[0063] The sequence numbers of the above-described embodiments of the present application are only for description, and do not represent the advantages or disadvantages of the embodiments.

[0064] In the above-described embodiments of the present application, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0065] The above only describes the preferred embodiments of the present application. It should be noted that, for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should also be considered as the protection scope of the present application.

Claims

1. A process control method for preventing blooming in steel wire cord fabric, characterized in that, The method includes: Samples were taken from the raw rubber stage of the rubber compound used for calendering steel cord fabric to determine the free sulfur content in the compound, and the conversion rate of insoluble sulfur in the compound was calculated based on the measurement results. The preset first threshold is compared with the calculated conversion rate of insoluble sulfur; If the calculated conversion rate of insoluble sulfur is greater than the first threshold, the result of the rubber compound being unqualified will be output. The first threshold is calculated using the following method: Establish a pre-defined relationship between the conversion rate of insoluble sulfur and blooming during the rubber supply stage for steel cord calendering. Based on this correspondence, a second threshold is determined to achieve a completely bloom-free steel wire cord fabric during the glue supply stage; The first threshold was calculated using the second threshold and based on the development relationship of the conversion rate of insoluble sulfur in the rubber compound at each stage of steel cord calendering; The conversion rate of insoluble sulfur in the rubber compound during the calendering stage of steel cord fabric showed the following growth rates in sequence: first growth rate, second growth rate, and third growth rate. The formula for calculating the first threshold is: First threshold = Second threshold - (First growth rate + Second growth rate + Third growth rate); The formula for calculating the conversion rate of insoluble sulfur in rubber compounds is: Conversion rate of insoluble sulfur = Free sulfur content / Mass fraction of insoluble sulfur 100%, wherein the mass fraction of insoluble sulfur is obtained from the formulation table of the rubber compound; The growth rate of insoluble sulfur conversion rate in the entire steel cord calendering and rubber supply system is the highest from the raw material stage to the extrusion stage, the second highest from the extrusion stage to the refining stage, and the third highest from the refining stage to the rubber supply stage.

2. The process control method for preventing blooming of steel wire cord fabric according to claim 1, characterized in that, The first threshold is 14.5%.

3. The process control method for preventing blooming of steel wire cord fabric according to claim 2, characterized in that, The method further includes: presetting a first threshold.

4. The process control method for preventing blooming of steel wire cord fabric according to claim 3, characterized in that, The second threshold is 20%.

5. The process control method for preventing blooming of steel wire cord fabric according to claim 4, characterized in that, The free sulfur content in the rubber compound was determined using physical separation techniques.

6. The process control method for preventing blooming of steel wire cord fabric according to claim 5, characterized in that, If the calculated conversion rate of insoluble sulfur is less than or equal to the first threshold, the steel cord calendering process continues.

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