Study has been done on the reaction mechanism of a series of sulphenyl chloride compounds as anti-scorch agents. Anti-scorch time was influenced not only by the quantities but the kinds of the agents. So two retar-der types of the reaction must be considered besides prohibition type.
As the result, it was found that when the residue of the agents was much at scorch point, anti-scorch time related linearly to the rate constant of the reaction of the agents, and that when the residue was little at scorch point, the time related to the constant in inverse proportion.
In our experiments, the former relation came into existence.

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It was reported that a series of sulphenyl chloride compounds were effective as anti-scorch agents. In this report the reaction of the agents was accounted on the basis of LCAO-MO (Linear Combination of Atomic Orbital-Molecular Orbital) theory.
As the results of calculations, it was found that the more unstable the highest occupied energy levels were, the smaller the anti-scorch time was, and that the logarithm of the anti-scorch time, log (t-t₀), was related to the highest occupied energy level X_lv, where t₀ and t were scorch time of the control recipe and the compounds including the agents respectively. But it must be remarkable that it becomes appear to point out the phenomenon of retarder-type, when X_lv is more stable than needs.
As the results of investigation, it will be assumed that the agents react as follows;
+δ-δ
ANH₂+S₈→→k₁ANH₂.S.S……S.
-δ-δ
2ANH₂.S.S……S.+R-S-Cl→k₂ANH₂.S.S……S.SR
ANH₂.S.S……SCl
+δ-δ
ANH₂.S.S.S……S.+Ruber→k₃ Vulcanization
Where ANH₂ and R-S-Cl are vulcanization accelerater and anti-scorch agent respectively.

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In order to obtain calcium carbonate which is combined chemically to SBR, we tried to cover a part of surfaces of calcium carbonate with SBR latex which was perliminarrily treated with thiolacids.
A typical example is as follows; SBR latex was treated with thioglycolacid under several conditions, and was reacted with calcium hydroxide. Into the reaction product a stream of carbon dioxide was introduced.
In these ways, much better reinforcing fillers compared with any of calicium carbonate treated by known agents were obtained for SBR. For example, 300% modulus was about twice, and tensile strenght at break was triple as untreated calcium carbonate.

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As reinforcing agents, carbon black, white carbon, etc. are used in rubber industry. However, carbon black makes impossible to color the rubber stock freely. While white carbon is not enough to reinforce the stock.
For the purpose of improving these faults, some reinforcing agents were prepared principally from urea resin. The agents were loaded into NR, SBR and NBR. After valcanization, the results of reinforcement were observed.
Varying the condition for preparation, some kinds of urea were prepared. And other sorts were obtained adding some resins, such as acrylamide, melamine or cpoxy resin, to the urea resin. From the values of tensile strength, elongation, modulus, hardness etc. of the valcanizatess, the effectiveness of the resin reinforcing agents were estimated.
In conclusion, it was found that the urea resin blended with acrylamide was almost satisfactory.

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When vulcanized natural rubber is heat-treated in the autoclave under a steam pressure of 10kg/cm², naturally its tensile strength will decline depending on the duration of vulcanization before such treatment. However, there will be no difference in tensile strength corresponding to that in vulcanized degree.
This fact shows that a low-vulcanized rubber passes the optimum vulcanization point to shift into what seems a relatively level region and there the rubber seems to deteriorate under the heat of treatment.

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