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Reasons and considerations for the hardening of silica gel tube
Silicone tube in the production of a careless mistake may cause the quality of silicone tube. The following is the main reason for the change in the silicone tube and the hardening of the cause and the attention in the production.
The yellow and hardening of the silicone tube is mainly formed by aging. Controlling yellowing and hardening is the process of controlling the aging process. However, aging is divided into thermal aging, oxygen aging, ozone, gas corrosion aging, heavy metal oxidation aging. Reaction aging, UV aging, etc.. Also divided into material aging, pH imbalance. Broken chain, etc..
So in the production of silicone hose should pay attention to the following 10 things.
1, the raw material of their own resistance to yellowing, for example, the NR of the aging resistance than SBR and BR, etc..
2, accelerator system of collocation. Promoters can use M and DM to achieve the 4 level, but the whole system needs to be adjusted. The use of anti yellowing enhancers such as two dithiocarbamate on yellow Bianyou benefits, but at the expense of great property and operation. The faster the cure rate, the less chance of a broken chain, and the degree of aging has been suppressed. But at the same time, the sacrifice of the comprehensive property. Because of the fast curing and the formation of a slow curing bond is different. Such as pulling force tear, etc.. But the elastic brittle will increase.
3, hot press temperature control, the temperature is not more than 150 degrees, and even extreme points, then 140 degrees the following effect is better. Otherwise, a lot of material on the thermal aging process. High temperature, is an important factor in the aging of materials.
4, the use of titanium dioxide, the use of titanium dioxide is intended to reflect the role of the surface to form a mirror, so that ultraviolet light can not penetrate the rubber, but also similar to the surface treatment. The more dosage is, the better the anti - aging effect is, the smaller the particle size is, the better the anti - aging effect is.
5. The control of heavy metals, for example, zinc oxide, calcium carbonate, oil and many contain heavy metals, especially some cheap materials and so on. If the heavy metal content is high, then the heavy metal will produce oxidation and discoloration. Yellow is extremely easy to occur.
6, the use of oil: oil to be less, especially the chain alkyl can not be added to the general rubber, because the compatibility is poor, oil leakage, while the surface of the oil, but also to the surface of the additives, etc.. But sometimes we will find a strange phenomenon is that a cup of naphthenic oil and a cup of white mineral oil while drying, naphthenic oil color, and white mineral oil do not change color. Is that white mineral oil resistant yellow Bianhao.
7, TS2 and T90 control: it should be a little less sulfur, the more to the positive point, the more serious the chain. Broken chain is aging. The effect of T90 is better than T100.
8, pH adjustment: Compound weak acidic, on the curing reaction will have slight inhibitory effect, but also control the intensification of chain scission.
9, the use of antioxidant. BHT is good for the protection of heat and oxygen. SP and MB production coordination effect, the effect is also very good. Of course, the premise is the quality of the material.
10, general one trick: to prevent the main point of view of UV, it is the addition of anti UV agent.
In short, in the production of silicone tube to pay attention to the above 10 points should be better to prevent the silicone tube to become yellow and hard. Silicon rubber hose production but also a profound technical activities, later will continue to share more dry, welcome everybody attention.
This paper is from Shenzhen,, id=560?
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