Abstract
The analysis points out that the factors affecting the adhesion between the inner nozzle and the valve mainly include valve handling and preservation, inner nozzle rubber formulation and quality fluctuation, inner nozzle rubber pad vulcanization control, process operation and production environment, inner nozzle rubber pad fixation and inner tube vulcanization, etc., through proper handling and preservation of valves, control of inner nozzle compound formulation and quality fluctuations, stabilization of inner nozzle rubber pad vulcanization conditions, strict process operation and environmental maintenance, inner nozzle rubber pad fixation and inner tube vulcanization to meet the requirements of the process Condition and other measures can improve the adhesion between the inner nozzle rubber and the valve and ensure the quality of the inner tube.
1. Effect and control of valve nozzle treatment and preservation on adhesion
The tire valve is an important part of the inner tube. It is generally made of copper and is connected to the inner tube carcass as a whole through the inner nozzle rubber pad. The adhesion between the inner nozzle and the valve directly affects the safety performance and service life of the inner tube, so it must be ensured that the adhesion meets the standard requirements. In the process of inner tube production, it generally goes through processes such as valve pickling, scouring, drying, preparation of inner nozzle rubber pad, rubber pad and valve vulcanization in the same mold, etc. Brush the glue, dry it and fix it on the perforated inner tube tube until a qualified inner tube is vulcanized. From the production process, it can be analyzed that the factors affecting the adhesion between the inner nozzle and the valve mainly include valve processing and preservation, inner nozzle rubber formulation and quality fluctuations, inner nozzle rubber pad vulcanization control, process operation and production environment, inner nozzle rubber. In terms of pad fixing and inner tube vulcanization, corresponding measures can be taken to control the above influencing factors, and finally achieve the purpose of improving the adhesion between the inner nozzle and the valve and ensuring the quality of the inner tube.
1.1 Influencing factors
Factors that affect the adhesion between the valve and the inner nozzle include the selection of the copper material for processing the valve, the control of the processing process, and the processing and preservation of the valve before use.
The copper material for processing the valve generally chooses brass with a copper content of 67% to 72% and a zinc content of 28% to 33%. The valve processed with this kind of composition has better adhesion to the rubber. . If the copper content exceeds 80% or is lower than 55%, the adhesion to the rubber compound is significantly reduced.
From copper material to finished valve, it needs to go through copper bar cutting, high temperature heating, stamping, cooling, machining and other processes, so there are certain impurities or oxides on the surface of the finished valve; if the finished valve is parked for too long or the ambient humidity If it is too large, the degree of surface oxidation will be further aggravated.
In order to eliminate impurities or oxides on the surface of the finished valve, the valve must be soaked with a specified composition (usually sulfuric acid, nitric acid, distilled water or demineralized water) and a concentrated acid solution for a certain period of time before use. If the composition and concentration of the acid solution and the soaking time do not meet the specified requirements, the treatment effect of the valve may be deteriorated.
Take out the acid-treated valve and rinse the acid with clean water. If the acid solution is not thoroughly treated or rinsed cleanly, it will affect the adhesion between the valve and the rubber compound.
Dry the cleaned valve with a towel, etc., and put it in the oven to dry in time. If the acid-treated valve valve is exposed and stored for more than the time specified in the process, oxidation reaction will occur on the valve surface, and it is easy to regain moisture or stick to dust, oil, etc.; if it is not wiped cleanly, it will be on the valve surface after drying. Form water stains and affect the adhesion between the valve and the rubber; if the drying is not thorough, the residual moisture on the surface of the valve will also affect the adhesion of the valve.
The dried valve should be stored in a desiccator to keep the surface of the valve dry. If the humidity of the storage environment is too high or the storage time is too long, the surface of the valve may be oxidized or adsorbed moisture, which will affect the adhesion to the rubber compound.
1.2 Control measures
The following measures can be taken to control the above-mentioned influencing factors:
(1) Use copper material with good adhesion to the rubber to process the valve, and copper material with a copper content exceeding 80% or less than 55% cannot be used.
(2) Make sure that the valves of the same batch and specification are made of the same material, and make the cutting, heating temperature, stamping pressure, cooling time, machining, parking environment and time consistent, so as to reduce the change of material and processing procedure. Decrease in material adhesion.
(3) Increase the detection strength of the valve, generally according to the proportion of 0.3% sampling, if there is an abnormality, the sampling proportion can be increased.
(4) Keep the composition and ratio of the acid solution for valve acid treatment stable, and control the time for soaking the valve in the new acid solution and reused acid solution to ensure that the valve is thoroughly treated.
(5) Rinse the acid-treated valve with water, dry it with a towel or a dry cloth that does not remove debris, and put it in an oven to dry in time.
(6) After drying, the valves should be inspected one by one. If the base is clean and shiny, and there is no obvious water stain, it means that the treatment is qualified, and it should be stored in the dryer, but the storage time should not exceed 36 hours; if the valve base Green red, dark yellow and other colors, or obvious water stains or stains, it means that the treatment is not thorough, and further cleaning is required.
2. Influence and control of inner nozzle glue formula and quality fluctuation on adhesion
2.1 Influencing factors
The influence of the formula of the inner nozzle and the fluctuation of the quality of the rubber on the adhesion of the rubber valve is mainly manifested in the following aspects:
If the formula of the inner nozzle contains low glue content and many fillers, the fluidity of the rubber will be reduced; if the type and variety of accelerators are not selected properly, it will directly affect the adhesion between the inner nozzle and the valve; Zinc oxide can improve the adhesion of the inner nozzle, but when the particle size is too large and the impurity content is too high, the adhesion will decrease; if the sulfur in the inner nozzle is precipitated, it will destroy the uniform dispersion of sulfur in the inner nozzle. , which reduces the adhesion of the rubber surface.
If the origin and batch of the raw rubber used in the inner nozzle compound change, the quality of the compounding agent is unstable or the origin changes, the rubber compound has a short scorch time, low plasticity, and uneven mixing due to operational reasons, all of which will cause the inner nozzle compound. The quality fluctuates, which in turn affects the adhesion between the inner nozzle rubber and the valve.
When making the inner nozzle rubber film, if the number of thermal refining times is not enough and the thermoplasticity is low, the extruded film will be unstable in size, large in elasticity and low in plasticity, which will affect the fluidity of the rubber compound and reduce the adhesive force; if the inner nozzle rubber film exceeds The storage time specified by the process will cause frosting of the film and affect the adhesion; if the parking time is too short, the fatigue deformation of the film under the action of mechanical stress cannot be recovered, and the fluidity and adhesion of the rubber material will also be affected.
2.2 Control measures
Corresponding control measures are taken according to the influence of the inner nozzle formula and the quality fluctuation of the rubber on the adhesion:
(1) In order to optimize the formula of the inner nozzle, the rubber content of the inner nozzle should be reasonably controlled, that is, to ensure the fluidity and adhesion of the rubber, and to control the production cost. Strictly control the particle size and impurity content of zinc oxide, control the vulcanization temperature of the inner nozzle, the operation steps and the parking time of the rubber to ensure the uniformity of sulfur in the rubber.
(2) In order to ensure the stability of the quality of the rubber compound in the inner nozzle, the origin of raw rubber and compounding agents should be fixed, and batch changes should be minimized; process management should be strictly controlled to ensure that the equipment parameters meet the standard requirements; Dispersion uniformity and stability in the rubber compound; strict mixing, glue, storage operation and temperature control to ensure that the scorch time and plasticity of the rubber compound meet the quality requirements.
When making the inner nozzle rubber film, the rubber materials should be used in sequence; the hot refining and fine refining should be uniform, the number of times of tamping should be fixed, and the cutting knife should be penetrated; the inner nozzle film parking time should be controlled within 1 ~ 24 h , to avoid the rubber material not recovering from fatigue due to short parking time.
3. Influence and control of vulcanization of inner mouth rubber pad on adhesion
Selecting the valve of suitable material and handling and storing it according to the requirements, keeping the formula of the inner nozzle rubber reasonable and the quality stable is the basis to ensure the adhesion between the inner nozzle rubber and the valve, and the vulcanization of the inner nozzle rubber pad and the valve (that is, the rubber nozzle) Vulcanization) is the key to ensuring adhesion.
3.1 Influencing factors
The influence of nozzle vulcanization on the adhesion between the inner nozzle and the valve is mainly reflected in the filling amount of the rubber compound and the control of vulcanization pressure, temperature and time.
When the rubber nozzle is vulcanized, the valve nozzle and the inner nozzle rubber film are generally put into the special combined mold for the rubber nozzle. If the filling amount of the rubber material is too large (that is, the area of the inner nozzle rubber film is too large or too thick), after the mold is closed, the excess rubber material will overflow the mold to form a rubber edge, which will not only cause waste, but also cause the mold to not close properly and cause rubber pads. It is not dense and affects the adhesion between the inner nozzle rubber and the valve; if the filling amount of the rubber material is too small (that is, the area of the inner nozzle rubber film is too small or too thin), after the mold is closed, the rubber material cannot fill the mold cavity, which will directly reduce Adhesion between the inner nozzle and the valve.
Under-sulfur and over-sulfur of the nozzle will affect the adhesion between the inner nozzle and the valve. The vulcanization time is generally a process parameter determined according to the rubber used in the nozzle, the steam temperature and the clamping pressure. It cannot be changed at will when other parameters remain unchanged; however, it can be adjusted appropriately when the steam temperature and clamping pressure change. , to eliminate the influence of parameter changes.
3.2 Control measures
In order to eliminate the influence of the vulcanization process of the nozzle on the adhesion between the inner nozzle and the valve, the theoretical amount of rubber used for vulcanization of the nozzle should be calculated according to the volume of the mold cavity, and the area and thickness of the inner nozzle film should be adjusted according to the actual performance of the rubber. In order to ensure that the amount of rubber filling is appropriate.
Strictly control the vulcanization pressure, temperature and time of the nozzle, and standardize the vulcanization operation. Nozzle vulcanization is generally done on a flat vulcanizer, and the pressure of the vulcanizer plunger must be stable. The vulcanization steam pipeline should be reasonably insulated, and if conditions permit, a sub-cylinder or steam storage tank with appropriate volume should be installed to ensure the stability of steam pressure and temperature. If conditions permit, the use of equivalent vulcanization automatic control can eliminate the adverse effects caused by changes in parameters such as clamping pressure and vulcanization temperature.
4. Influence and control of process operation and production environment on adhesion
In addition to the above links, all the changes or unsuitability of the operation process and the environment will also have a certain impact on the adhesion between the inner nozzle and the valve.
4.1 Influencing factors
The influence of process operation on the adhesion between the inner nozzle rubber and the valve is mainly reflected in the difference between the operation and the standard of the valve rubber pad in the production process.
When the valve is subjected to acid treatment, the operator does not wear gloves as required to operate, which will easily contaminate the valve; when the valve is immersed in acid, the swing is uneven or the time control is not appropriate. The inner nozzle rubber is deviated in the process of hot refining, thin extrusion, tablet pressing, storage, etc., resulting in fluctuations in the quality of the film; when the inner nozzle rubber is vulcanized together with the valve, the mold or valve is skewed; the temperature, pressure and temperature during vulcanization There is an error in time control. When the vulcanized valve is roughened at the bottom and edge of the rubber pad, the depth is inconsistent, the rubber powder is not cleaned cleanly, and the glue paste is unevenly brushed, etc., which will affect the adhesion between the inner nozzle rubber and the valve.
The influence of the production environment on the adhesion between the inner nozzle rubber and the valve is mainly manifested in that there are oil stains and dust in the parts and spaces in contact with or storage of the valve and the inner nozzle rubber/sheet, which will contaminate the valve and the inner nozzle rubber/sheet; The humidity of the working environment exceeds the standard, which makes the valve and the inner nozzle rubber/sheet absorb moisture and affects the adhesion of the valve and the inner nozzle rubber.
4.2 Control measures
For the difference between the process operation and the standard, it should be done:
When the valve is subjected to acid treatment, the operator should wear clean gloves to operate according to regulations; when the valve is immersed in acid, it should swing evenly; soak it in new acid solution for 2-3 s, and then extend the soaking time appropriately; After taking it out of the liquid, immediately rinse it with water for about 30 minutes to ensure thorough rinsing; the valve after rinse should be wiped off with a clean towel that does not remove debris, and then put it in an oven to dry for 20 to 30 minutes. min; the dried valve should not be stored in the dryer for more than 36 hours. The parameters of the inner nozzle rubber should be kept stable during hot refining, thin extrusion, tablet pressing, storage, etc., without obvious fluctuations; during vulcanization, the mold and valve should be kept from skewed, and the vulcanization temperature, pressure and time should be properly controlled. The bottom and edge of the valve rubber pad should be shaved in a uniform depth, the rubber powder should be thoroughly cleaned with gasoline during shaved, and the concentration and interval of the glue paste should be controlled accurately, so that the inner nozzle rubber and the valve will not be affected by the process operation. Adhesion of the mouth.
In order to avoid secondary pollution of the valve and inner nozzle rubber/sheet, the valve acid treatment room, oven, dryer, inner nozzle film preparation and flat vulcanization machine and workbench should be kept clean, free of dust and oil; the environment is relatively The humidity is controlled below 60%, and the heater or dehumidifier can be turned on for adjustment when the humidity is high.
5. Ending
Although the adhesion between the valve and the inner nozzle is only a link in the production of the inner tube, the ring has an important influence on the safety performance and service life of the inner tube. Therefore, it is necessary to analyze the factors affecting the adhesion between the valve and the inner nozzle, and take targeted solutions to improve the overall quality of the inner tube.
Post time: Nov-03-2022