Rubber mixing practiceSeveral common quality problems
1. The charred
Mild charred mixing rubber surface is not smooth, plasticity;Badly charred, characterization of surface and internal generates sizes have obvious elastic properties of the practice of colloidal particles or film (also known as gum knot).Reasons are as follows:
(1) formula for curing agent, promoter collocation is improper or improper selection, vulcanization too fast;Dosage of curing agent, promoter too much;No added antiscorching agent;
(2) mixing processing Mixing adhesive capacity is too large;Mixer, mixing mill cooling is not enough;Initial charging temperature is too high;Discharging temperature is too high;Curing agent, promoter to join mixer or the order of the time is not correct;Uneven curing agent, promoter scattered, local concentration;Leakage or too late to join antiscorching agent;Rubber not fully cooling, such as BoTong cooling or cooling water) or for packaging;Parking time is too long;Park temperature, humidity is too high;
(3) the process problems in front of the vulcanizing agent and/or promoter to error;Vulcanizing agent and/or promote agent to prepare too much;Antiscorching agent said leakage;
2. The scattered unevenly
3. The spray frost
Because the compound out rubber surface and form a layer of spray is similar to the phenomenon of "white frost" called frost phenomenon.
4. The hardness is too high too low or uneven
5. Plastic through greater than small or uneven
Reason: rubber plastication plasticity is not appropriate;Mixing time is too long, too short;Mixing temperature too high or too low;With glue not mixed evenly;Mixed uneven;Soften the plasticizer more or less;Carbon black to add too much, too little, or used the wrong species.
6. Cooperate with the agent
Reason: insufficient raw rubber molding;Raw rubber or a/some of compound be affected with damp be affected with damp, moisture content is too high;Large amount of glue;Roller spacing is too large, powder compound directly fall on the roller is pressed into flake;Roller temperature is too high (such as mixing the early high temperature formed hungry too much carbon black gel solids, etc.);Powder compound containing coarse particles or cluster;Gel too much;
7. Contract too
Reason: not vulcanizing rubber - plastic was low;Mixing time is too short;Mixer mixing time is too long, leading to come;Add rubber vulcanization agent - rubber scorch time is too short, began to scorch;Storage time is too long, Mooney viscosity too high or began to scorch;
Textured (colloidal particles) with 8.
Reason: for without sulfur rubber, mixer mixing time is too long, too much carbon black gel;To add sulfur rubber, caused by mixing temperature, temperature overheat charred, or mixed with coke burning rubber;
9. At the beginning of sulfur slow or fast
Reason: the vulcanization system of compound weighing inaccuracy, mismatch or leak with (e.g., ZnO and leakage or ST - ACD);Reinforcing agent mismatch error (such as carbon black variety) and mixing process (such as roller), such as temperature, mixing time sequence and improper master, etc.;
10. The layered
Reason: rubber rubber mix the incompatibility of other rubber.Such as polarity rubber NBR, mixed with nonpolar rubber EPDDM;Also, such as natural rubber blending butyl rubber;
Pollution of 11.
Reason: due to dust, dirt, sand and other materials of the elastomer and rubber medicine physical pollution;Different rubber mixing together of pollution;For different compound use different weighing spoon;Improper use of additives;Residues of compound mixing materials plate not clear;Mixer aging oil seal oil;Residual glue accumulation in banbury mixer seal;Around the mixer and tablet press not neat;
12. Take off the roll or roller
Reason: to take off the roller - gel rate is too low;Gelatin hard;When mixing rubber roller spacing is too large;Special collagen itself can take off the roller;
Sticky roller - roller temperature is too high, roller spacing is too small;The low plasticity;Softening oil too much or one-time add too much;Mixing time is too long, or in violation of the loading sequence, such as asphalt and rosin behind the load.
13. Physical and mechanical properties is not qualified or not
Reason: compound weighing inaccurate, especially reinforcing agent and plasticizer;Vulcanizing machine and promoter leakage match or mismatch;Mixing excessive;Sequence is not reasonable or mixing unevenly, easy to cause inconsistent performance;
14. The performance of the difference between each batch of rubber
Reason: the initial charging temperature;There are differences between the cooling water and temperature;On the top bolt pressure difference;Compound weighing error;Compound differences between different batch number;Use alternative chelating agent;Is not the same as the evacuation time and temperature;The different operator tableting machine processing in a different way;Dispersion degree is not the same;