Plasticizer for rubber processing products

one Petroleum plasticizer

It is one of the most used plasticizers in rubber processing. Plasticizing effect is good, the source is abundant, the cost is low. Petroleum plasticizers are prepared by distillation of appropriate crude oil at atmospheric and reduced pressure. The main varieties are operating oil, three line oil, transformer oil, oil, light heavy oil, paraffin, petroleum jelly, asphalt and petroleum resin, among which the most commonly used is operating oil.

1. Classification of operating oils

Operating oil is a high boiling fraction of petroleum, composed of complex hydrocarbon compounds with molecular weight from 300 to 600, with a wide molecular weight distribution. According to the main components of the oil, the operating oil can be divided into the following three types:

① Aromatic oil: mainly aromatic oil. Brown viscous liquid, best compatibility with rubber, good processing performance, fast absorption. Suitable for natural rubber and a variety of synthetic rubber; The disadvantage is pollution, suitable for dark rubber products.

② Naphthenic oil: mainly naphthenic hydrocarbons. Light yellow or transparent liquid, poor compatibility with rubber than aromatic oil, but less pollution than aromatic oil, suitable for NR and a variety of synthetic rubber.

Paraffin oil: also known as paraffin oil, mainly straight or branched paraffin. Colorless transparent liquid, low viscosity, poor compatibility with rubber, poor processing performance, slow absorption speed, mostly used in saturated rubber, little pollution or no pollution, suitable for light colored rubber products.

2. Characteristics of operating oil

(1) operating oil viscosity operating oil viscosity is higher, the more viscous oil, operating oil on the processing performance of rubber and vulcanized rubber properties are affected. The use of low viscosity operating oil, good lubrication, improved cold resistance, but in the process of volatile loss. When the flash point is lower than 180℃, the volatilization loss is greater, so special attention should be paid to it.

The viscosity of operating oil is closely related to temperature. At low temperature, the viscosity is higher, so the property of oil has a great impact on the low temperature performance of vulcanized rubber, using low temperature viscosity (at -18℃ kinematic viscosity) change less oil, can improve the low temperature performance of vulcanized rubber. The viscosity of high aromatic oil is more dependent on temperature than that of alkane oil.

The viscosity of operating oil is related to the heat of vulcanized rubber, and the heat of rubber products with high viscosity oil is high. The heat generation of aromatic oils is low at the same viscosity. With the increase of oil viscosity, the tensile strength and elongation increase, the flexure becomes better, but the fixed elongation stress decreases. Oils of the same viscosity, if added in equal volume, will have higher elongation than saturated oils.

2) Relative density in the petroleum industry is usually measured at 60℃ relative density. The relative density of rubber processing oil is important when rubber products are sold by weight. Generally, the relative density of aromatic oil is greater than that of paraffin oil and cycloparaffin oil. Rubber processing oils are often sold by volume, while in rubber processing they are prepared by weight.

(3) Aniline point add 5 ~ 10ml aniline in the tube line, and then add the same volume of test material, and then heat from the bottom until a uniform transparent solution, the temperature at this time is called the aniline point of the oil. Aromatic hydrocarbon plasticizer has the closest molecular structure to aniline and is easily soluble in it, so the aniline point is the lowest. The oil with low aniline point and diene rubber are soluble and can be added in large quantities without frost spraying. On the contrary, the oil with high aniline point needs to be soluble with raw rubber at high temperature, so it is easy to spray out of the surface when the temperature is reduced. The level of operating oleaniline point is essentially a mark of aromatic hydrocarbon content in oil. Generally speaking, operating oleaniline points in the range of 35 ~ 115℃ is more appropriate.

(4) Pour point (flow point) Pour point is the lowest temperature that can maintain flow and pour. This property can indicate the applicability to the process temperature of the product operation.

(5) Flash point is the temperature at which a mixture of steam and air can ignite under standard test conditions. The flash point of operating oil is directly related to vulcanization, storage and fire prevention of rubber, and also can measure the volatility of operating oil.

(6) Neutralization value neutralization value is the scale of operating oil acidity, acidity can cause a significant delay in rubber vulcanization speed. The neutralization value is expressed as the number of milligrams of KOH required to neutralize the acid content of 1 gram of operating oil.

In addition, the refractive index, appearance color and volatile matter of the oil can also reflect its composition.

3. Effect of operating oil on rubber processing properties

(1) The influence on mixing

The absorption rate of rubber oil and oil composition, viscosity, mixing conditions: general viscosity is low, aromatic hydrocarbon content is high, high temperature, absorption fast. But the amount of oil, so that the dispersity of carbon black in rubber becomes poor, must be added in batches. In addition, adding oil in mixing can reduce heat generation and energy consumption.

(2) The impact on the pressure out

Adding an appropriate amount of oil to the rubber material can soften the rubber material, smooth surface of the pressing semi-finished product, small pressing expansion and fast pressing.

(3) Influence on vulcanization

The vulcanization rate tends to slow down with the increase of oil filling amount. The addition of oil, vulcanizing agent, accelerator in rubber concentration reduction, so that the vulcanization speed.

The operation oil containing more aromatic oil has the effect of promoting the coke burning and accelerating the vulcanization of rubber.

4. Characteristics of operating oils used in several types of rubber

(1) SBR: aromatic oil is the best, so that the tensile strength and elongation are improved, the fixed elongation stress is decreased, and the flexural resistance of vulcanized rubber is good.

(2) BR: Due to the large amount of carbon black filling, the amount of operating oil is more, which has no significant effect on performance.

(3) CR: Aromatic hydrocarbon is the best choice, followed by naphthenic oil, can not use paraffin oil.

(4) NBR: generally do not operate oil, with synthetic plasticizer.

(5) IIR: use low viscosity oil, naphthenic oil or paraffin oil, not aromatic oil.

(6) EPDM: generally, aromatic oil is not used, but paraffin oil and naphthenic oil are used.

two Coal tar plasticizer

The main varieties are: coal tar, ancient Malone, coal pitch and RX-80 resin. Good compatibility with rubber, and can improve the aging resistance of rubber. One of the most commonly used is Gumaron resin, which is both a plasticizer and a stickier, especially suitable for synthetic rubber.

1. Coal tar

Black viscous liquid, smelly, pollution, easy to mix with glue, can dissolve sulfur, prevent frosting, can improve the aging resistance of products, increase the adhesion of SBR.

2. Gummalone resin

According to the degree of polymerization, guomarone resin is divided into liquid guomarone resin and solid guomarone resin.

Liquid gumalon: plasticizing, viscosifying effect, better than solid gumalon, but low reinforcement, not convenient to use.

Solid gumaron: good compatibility with rubber, plasticizing, stickiness and reinforcing effect, help disperse carbon black, can dissolve sulfur and stearic acid, prevent frosting, can improve the adhesive and vulcanized rubber tensile strength and hardness, dosage is less than 15.

According to the range of the ancient Malone softening point its application is also different, generally, the softening point is 5 ~ 30 deg C is viscous liquid, belongs to the liquid ancient Malone, in addition to styrene butadiene rubber in synthetic rubber and natural rubber for plasticizer, adhesive and regenerative rubber regeneration agent; The viscous lumpy gummalon with softening point of 35 ~ 75℃ can be used as plasticizer, adhesive or auxiliary reinforcing agent. Brittle solid gumalone resin with softening point between 75 ℃ and 135℃ can be used as plasticizer and reinforcing agent.

3. Rx-80 resin

Reactivity is very high, can plasticize, increase viscosity and reinforcing effect, but also increase the luster of color glue.

3. Pine tar series plasticizer

Pine tar is the residual material after removing turpentine by dry distillation of pine root. The main varieties are pine tar, rosin, pine oil, tall oil and so on. The most commonly used is pine tar, can improve the adhesive, cold resistance, help with the dispersal of the agent, delay vulcanization, dynamic heat generation. Rosin is used at glue pulp and the glue that combines with cloth surface more.

Four. Adipose oil is plasticizer

Adipose oil department plasticizer is the fatty acid that is made by vegetable oil and animal oil, ointments and other.

Stearic acid: it can promote the dispersion of ZnO and carbon black in rubber, and it is also an important sulfide active agent.

Ointments: black ointments, white ointments. The carbon black is easy to disperse, beneficial to calendering and pressing, and the semi-finished product has smooth surface, small shrinkage rate and large stiffness, which can prevent frosting. Easy to mold after vulcanization, but too much will delay vulcanization.

Others include glycerin, castor oil, soybean oil, zinc stearate, etc.