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Vulcanization method for removing restricted substances in chlorinated compounds

in the past, some products were used to crosslink chlorinated compounds, which, in the view of automobile manufacturers, were either restricted or would soon be banned. Nowadays, among the methods of vulcanizing chlorinated compounds, lead containing compounds and thiourea based vulcanization methods are the most respected. Recently, some automobile production directives have restricted the use of lead curing agents, and their use may be banned in the near future. Long term research on the use of thiourea curing agents may also limit their use in the near future. As many automobile manufacturers emphasize the material specifications of restricted substances, it is urgent to find the corresponding vulcanization method as soon as possible to meet the needs of many automobile manufacturers

it is found that some chemical products can replace the vulcanization method based on lead and thiourea used in the past. These curing agents can be used to develop products that can not only be produced and processed now, but also meet the high requirements of the specifications without using restricted and prohibited products. This paper describes how to develop an alternative vulcanization method containing chlorinated compounds using non limited curing agents through examples

requirements of new vulcanization method

the first standard of lead-free vulcanization method is that the composition (or variation of composition) of the new vulcanization method must be able to vulcanize all chlorinated compounds. This is equivalent to putting forward a high requirement, because nowadays, chlorinated compounds are widely used in automotive applications. Cr, CIIR, Co, eco, ACM and other compounds can use new vulcanization methods to replace the conventional lead vulcanization method and thiourea vulcanization method. The new vulcanization method needs to have good processing operation safety, maintain good heat resistance and oil resistance, and the cost is moderate, so it does not need to use substances that may be restricted. The current vulcanization method can meet one or another requirements for chlorinated compounds, but it is quite difficult to find a vulcanization method that can meet all requirements. Rhein Chemie has tested some vulcanization methods and found that a vulcanization method based on rhenogran triazine TM mixed with rhenogran hpca and other components can meet the requirements of most chlorinated compounds

experimental data of eco

epichlorohydrin (ECO) is one of the most difficult chlorides to synthesize. If we want to remove lead containing substances, it will be more difficult to synthesize Eco, because the currently used vulcanization method contains lead substances. The end of this paper shows that various forms of Trichlorobenzene can be used for vulcanizing eco and other chlorinated compounds. Most vulcanization methods have some defects, that is, they cannot easily meet the requirements of the European automotive directive. In the developed compounds, we will show how to use Trichlorobenzene vulcanization in eco to achieve all key product properties. Next, we will show a typical chloroprene compound made by a similar vulcanization method

the main standards of the new epichlorohydrin vulcanization method are: they can perform good scorching resistance, non-toxic, maintain heat resistance, produce better physical properties, have better in mold fluidity and save costs. The first problem encountered in using Trichlorobenzene vulcanization to replace the traditional lead vulcanization method is that Trichlorobenzene is easy to scorch. All tests were carried out using standard DIN and ASTM procedures. In Table 1, we can see the influence of different retarders on Trichlorobenzene

the data in Table 1 shows that the Trichlorobenzene vulcanization method without retarder does not have enough service life to be used in normal production environment. Vulkalent e/c (a treated aromatic sulfonamide) and b/c (phthalic anhydride) either do not significantly delay the vulcanization process, or significantly reduce their physical properties to meet the specified characteristic requirements. Only when CTP is between 0.5 and 1.0phr (parts per hundred grams), it can maintain the anti scorching property and achieve the physical properties necessary for final use. For the best service life, it is more than 14 days. At this time, rhenogran TP (zinc dibutylphosphorodithioate) can be added, as shown in Table 2. Even after 14 days of room temperature aging, a more stable Mooney viscosity can be obtained

after adding ctp-80 and tp-50, the compound has good Mooney viscosity and service life. Now it is necessary to heat the tension and module to ensure that the relevant finished products can meet the performance standards. At 0.5 ~ 0.7phr, the physical properties of the compound can be improved to meet the performance requirements of automotive applications by adding hpca-70. In Table 3, we can see the effect of adding hpca-70 to the compound

attention must be paid when adding hpca-70, as shown in Table 3, because when it is greater than 0.7phr, the anti scorching property may be lost

now that we have obtained the physical properties and have the required operating safety environment, the compound must undergo aging experiments to determine whether it can maintain its performance under more stringent conditions (125 ℃ hot air aging, 1000 hours). The results of long-term thermal aging of this compound are shown in Table 4

after 1000 hours of hot air aging at 125 ℃, the typical requirements for performance characteristics are: the change of hardness is less than 13 points, at least 130% elongation, and the minimum tensile strength is 8 MPa

the properties of all Trichlorobenzene compounds meet the minimum requirements, and show the best results and save costs when hpca-70 is 0.5phr. Compared with typical lead compounds, this compound is also very cost-effective, because the proportion of lead oxide is large. The unit cost of Trichlorobenzene compounds with much smaller specific gravity will be much lower, which makes it quite competitive with the conventional lead vulcanization method

now that we have designed a feasible vulcanization method based on Trichlorobenzene and tested it according to a representative technical specification of automotive fuel hose, we will determine whether this vulcanization method is also applicable to other applications

design injection molding epichlorohydrin using Trichlorobenzene vulcanization method

based on the previous work, we can establish a short experimental design to optimize the Trichlorobenzene vulcanization method for injection molding compounds. We choose a 2 made of Trichlorobenzene × two × 2, with CTP and TP as variables. The reason for keeping hpca constant is that if the amount of hpca is too high, the scorching resistance of the product will be eliminated. A special mixture of magnesium oxide, hydrotalcite and calcium carbonate is added to neutralize the hydrogen chloride produced in the vulcanization reaction. Table 5 shows the experimental design and the parameters used for each variable. The secondary reactions between the main variables were calculated by the least square estimation method

table 6 shows the actual results of eight experimental substances and compounds vulcanized with lead. All test objects were mixed and vulcanized using the same test procedure. The general results show that the scorching resistance of the new vulcanization method is basically the same as that of the old method, and even better, and the vulcanization speed is better. The physical properties of the new vulcanization method are comparable to those of the lead vulcanization method. Regardless of the changes in variables, their thermal aging data are roughly the same. The compression setting of the new vulcanization method is better than that of the old method. The tensile load can be minimized by optimizing the oil aging test, and the results show that the shrinkage in the oil aging test is less than the corresponding amount in the lead vulcanization method. All basic tests show that the new Trichlorobenzene vulcanization method can completely replace the lead vulcanization method, and the performance characteristics can remain unchanged. In order to optimize the acid absorption of magnesium oxide, calcium carbonate and hydrotalcite, further research may be needed

the data shows that the flow pattern similar to that of lead vulcanization can be achieved by using the following indicators. These indicators are: tmt- 7phr, ctp-07phr and tp- 3phr。 Based on this initial data, further tests were carried out with higher indicators and corresponding results were obtained

experimental data of chloroprene

since we have designed vulcanization methods for hose and mold applications, can we design similar vulcanization methods for chlorinated compounds? Although lead vulcanization is sometimes used for vulcanizing chloroprene, thiourea is more widely used in polymers. Thiourea is likely to be restricted by some automobile manufacturers, and even banned by the European Union like lead and other controlled chemicals. The following is an example of vulcanization of a chloroprene compound using MTT and rhenogran hpca. In this example, the conventional vulcanization method uses the zinc oxide vulcanization method using MBTS and TMTD as catalysts and magnesium oxide as acid absorbent. Compared with the conventional method, the new vulcanization method uses thiourea, lead or other restricted substances. The new vulcanization method is better than the conventional vulcanization method in terms of tension, modulus and characteristics after hot air aging for 336 hours at 125 ℃ (Table 8)

conclusion

the results of this paper show that using Trichlorobenzene and similar chemicals and CTP and rhenogran hpca as additives can design a cost-effective vulcanization method to meet the performance standards required for automotive applications. These formulas can be well balanced between processing parameters and performance characteristics, and can meet the strict requirements of injection mold application after optimization. The results show that the new vulcanization method can maintain or even improve the heat resistance, has good scorching resistance, and can achieve the high standard physical properties required by the final product. Because their density is relatively low compared with the very high lead oxide, they can save more cost

table 1

1 2 345 6 7

table chlorohydrin 100 100 100 100 100 100 100 100

stearic acid 11 11 11 1 1 1

n550 carbon black 50 50 50 50 50 50 50 50

calcium carbonate 5 55 55 5 5

rhenofit d/a 3 3 3 3 3 3

aflux 5411 11 1 1 1 1 1

ndbc 1.05 1.05 1.05 1.05 1.05 1.05 1.05

rhenogran Trichlorobenzene tm-70 11 11 11 1

vulkalent e 0.5 1.5

vulkalent b/c 0.5 1.5

rhenogran Ctp-80 0.5 1.5

Mooney viscosity

ml (1+4) 100 ℃, 1 day 89 85858179 76

ml (1+4) 100 ℃, 7 days 114 93911049087 81

ml (1+4) 100 ℃, 14 days>200 10488>200 95111 104

physical data

hardness, a 7269 no vulcanization 73717163

rebound rate 3331 no vulcanization 3 Limit protection: electronic limit 32293028

100% module, MPA 3.824 no vulcanization 4 2.7 3.4 1.8

300% module, MPA 96.4 no vulcanization 8.8 6.7 8.5 4.7

tension, MPA 10.8 9.8 no vulcanization 10.3 9.3 10.3 8

elongation, %470660 non vulcanization 470590490 690

Table 2

Table chlorohydrin parent mixture 162.5 162.5 162.5 162.5 162.5 162.5

Trichlorobenzene tm-70 1111 1 1 1

ctp-80 1111 1 1

tp-50 0.512

viscosity

ml (1+4) 100 ℃, the box is closed at 1 day temperature calibration 89 777775 74

ml.(1+4)