JP6168412B2 - Heat transfer oil - Google Patents

Description

The present invention relates to a novel heat medium oil, and more particularly to an ester heat medium oil derived from rosins which are non-edible plant materials.

Synthetic organic heat medium oils with excellent performance are known as heat medium oils that are widely used industrially, such as dialkylnaphthalene, hydrogenated triphenyl, dialkylbiphenyl, trialkylbiphenyl, dibenzyltoluene and the like. It is done. However, some of these synthetic organic heat transfer medium oils may have safety concerns when released into the environment, such as dibenzyltoluene and diethylbiphenyl. It is specified. Synthetic organic heat media have high stability, but have low decomposability, and remain in the environment and accumulate in living organisms.

In view of such environmental considerations, natural plant oils with excellent safety are attracting attention again. For example, it has been proposed to use a derivative of vegetable oil such as rapeseed oil, corn oil, safflower oil, etc. (the lower alcohol esterified product) as an electrical insulating oil (see Patent Documents 1 to 3). There is no teaching or suggestion to use as a medium oil.

By the way, since most vegetable oils are edible oils, diverting them to industrial uses such as heat transfer oils may be viewed as limiting the original use of food resources (hereinafter referred to as food problems). This idea is similar to the competition problem between “energy and food” in biofuel, for example.

From such a background, the appearance of a novel heat medium oil that is environmentally friendly and that is derived from non-edible natural products is highly desired.

JP 2000-72715 A Japanese Patent Laid-Open No. 9-259638 JP 2000-90740 A

An object of this invention is to provide the novel heat-medium oil which consists of a derivative | guide_body using a nonedible natural product from a viewpoint of environmental consideration and a food problem.

In order to solve the problems of the prior art, the present inventor has focused on esterified products obtained from rosins that are non-edible natural products. That is, as a result of intensive studies focusing on the characteristics of the rosin esters and the application correlation to the heat medium oil, it was found that specific rosin esters can solve the above-mentioned problems, and the present invention is completed. It came.

That is, the present invention contains at least one liquid rosin ester (hereinafter referred to as “specific rosin ester”) composed of rosins and monohydric alcohols having 1 to 10 carbon atoms. Related to medium oil.

According to the present invention, it is possible to provide a heat transfer oil that is environmentally friendly and that is a derivative using a non-edible natural product, so that there is no concern about the food problem.

Examples of rosins that are components of specific rosin esters include natural rosins such as gum rosin, tall oil rosin, and wood rosin. The natural rosin is preferably used after being subjected to a purification treatment such as distillation and recrystallization in consideration of the color tone and thermal stability of the obtained heat medium oil. The color tone of the purified rosin is 2 in terms of Gardner color. Hereinafter, it is more preferably 1 or less. Further, as the rosins, modified rosins such as disproportionated rosin and hydrogenated rosin can be used as necessary, and specific rosin esters derived from these modified rosins are derived from natural rosin and purified rosin. Compared to the specific rosin ester derived, it is excellent in thermal stability and oxidation resistance.

In order to obtain specific rosin esters, it is essential to use a monohydric alcohol having 1 to 10 carbon atoms as the alcohol. When an alcohol having more than 10 carbon atoms is used, the viscosity and fluidity of the obtained rosin ester tend to decrease, and as the molecular weight of the alcohol increases, rosin which is a plant-derived component in the rosin ester Since the content is also reduced, it is difficult to obtain the heat medium oil that is the object of the present invention. Among the monohydric alcohols having 1 to 10 carbon atoms, monohydric alcohols having 1 to 4 carbon atoms can be preferably used. Examples of the alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and tert-butyl alcohol, and these can be used alone or in combination of two or more. In addition, the plant-derived component rate of the rosin ester obtained can be further raised by using alcohol derived from biomass.

The method for producing the specific rosin ester is not particularly limited, and a conventionally known esterification method can be employed. The amount of each of the rosins and alcohols is not particularly limited, but is usually in the range of OH group / COOH group (equivalent ratio) of 0.8 to 1.5, preferably 0.9 to 1.3. To be determined. The esterification reaction is determined in consideration of the boiling point of the alcohol to be used, and the reaction temperature is usually 150 to 320 ° C, preferably 150 to 300 ° C, and the reaction time is usually about 10 to 24 hours. Furthermore, in order to shorten the reaction time, in the presence of an acid catalyst such as p-toluenesulfonic acid, a metal hydroxide such as calcium hydroxide or magnesium hydroxide, or a metal oxide such as calcium oxide or magnesium oxide. The esterification reaction may be allowed to proceed. The reaction can proceed while removing the generated water outside the system via a diversion pipe, and it is desirable to carry out the reaction under an inert gas stream in view of the color tone of the specific rosin ester obtained. The reaction may be carried out under pressure if necessary, or the reaction may be carried out in the presence of an organic solvent that is non-reactive with rosins and alcohols. Examples of the organic solvent include hexane, cyclohexane, toluene, xylene and the like. In addition, if it is necessary to distill off a use solvent and an unreacted raw material, what is necessary is just to carry out under reduced pressure suitably.

The specific rosin ester used in the present invention has an acid value of 2.0 mgKOH / g or less, preferably 1.0 mgKOH / g or less, and a viscosity at 40 ° C. of 2000 mPa · s or less, preferably 50 to 1500 mPa · s. The boiling point is 300 ° C. or higher, preferably 300 to 500 ° C. By reducing the acid value to 2.0 mgKOH / g or less, the corrosiveness to the metal with which the obtained heat medium oil comes into contact is suppressed, and it can be used stably for a long time. Moreover, the handling property as a heat-medium oil can be improved by setting it as the above viscosity and boiling point conditions.

Typical examples of various physical properties required for the heat transfer oil include flash point and thermal conductivity. The flash point of the specific rosin ester used in the present invention is usually 150 to 250 ° C, preferably 170 to 250 ° C. Further, the thermal conductivity (measured value at 150 ° C.) of the specific rosin esters is usually 0.11 to 0.15 W / m · K, preferably 0.12 to 0.15 W / m · K. The flash point and thermal conductivity of the specific rosin esters are both the same as the physical property values of the heat medium oil that is a typical commercial product, and it is presumed that they are suitable for the use of the heat medium oil of the present invention. it can.

The content of rosins that are plant-derived components in the specific rosin esters is preferably 50 to 90% by weight, more preferably 70 to 90% by weight. That is, it is because it can be widely adapted to the identification and labeling system of each country given to products that have a high plant-derived component ratio and can contribute to the environmental load, and it can be expected that the range of use of the heat transfer oil will be widened.

The heat medium oil of the present invention is characterized by containing specific rosin esters. The heat medium oil of the present invention is not limited to those prepared only from the specific rosin esters, and various known synthetic organic heat medium oils and vegetable oils may be used as necessary without departing from the objects and effects of the present invention. It may be appropriately blended with a heat medium oil. In addition, the heat medium oil of the present invention can be blended without particular limitation to various additives used in known heat medium oils, such as antioxidants, detergent dispersants, viscosity index improvers, pour points. Depressants, oiliness agents, antiwear agents, extreme pressure agents, corrosion inhibitors, metal deactivators, rust inhibitors, antifoaming agents, emulsifiers, demulsifiers, bactericides, colorants and the like.

Various physical properties of the obtained rosin esters were measured as follows.
Acid value: measured according to JIS K0070.
Viscosity: Measured at 40 ° C. using a B-type viscometer (product name “VISCO BLOCK VTB-250”, manufactured by Tokimec Co., Ltd., rotor No. HM-3).
Boiling point: A sample of 100 ml and a boiling stone were placed in a flask having an internal volume of 200 ml in which a T-tube was installed, and the thermometer mercury bulb was placed so that the upper end of the mercury bulb was at the center of the T-tube outlet. Subsequently, while heating with a mantle heater, the temperature at the start of distillation at a distillation rate of 3 to 4 ml per minute was read as the boiling point.
Content of rosins: The molecular weight of rosins was 302, the molecular weight of alcohols was X, and the following formula was used.
Rosin content (%) = [302 / (X + 302)] × 100
Flash point: Measured with a Cleveland open flash point measuring device according to JIS K2265.
Thermal conductivity: Measured at 150 ° C. using a thermal conductivity measuring device (trade name “ARC-TC-1000 type”, manufactured by Agne) according to the hot wire method (see JIS R2251-1).

Example 1
Table 1 shows measured values (acid value, viscosity, boiling point, flash point, thermal conductivity) of methyl ester of Chinese gum rosin (manufactured by Arakawa Chemical Co., Ltd., prototype) and plant-derived component ratio.

(Example 2)
Table 1 shows the measured values of methyl disproportionated rosin methyl ester (Arakawa Chemical Industries, Ltd., prototype).

(Example 3)
Table 1 shows the measured values of methyl ester of Chinese hydrogenated rosin (Arakawa Chemical Co., Ltd., prototype).

Example 4
Table 1 shows the measured values of ethyl disproportionated rosin ethyl ester (Arakawa Chemical Industries, Ltd., prototype).

(Example 5)
Table 1 shows the measured values of butyl ester of Chinese disproportionated rosin (manufactured by Arakawa Chemical Industries, Ltd., prototype).

In Table 1, Reference Example 1 is NeoSK-OIL1400, and Reference Example 2 is KSK-OIL260 (both are trade names manufactured by Soken Chemical Co., Ltd.).

As is clear from Table 1, the heat medium oil composed of the specific rosin esters shown in Examples 1 to 5 has various physical properties that are comparable to the commercially available heat medium oils of Reference Examples 1 and 2. I understand that.

Claims (5)

A heat medium oil comprising at least one liquid rosin ester composed of rosins and monohydric alcohols having 1 to 10 carbon atoms. The heat medium oil according to claim 1, wherein the rosin is at least one selected from the group consisting of refined rosin, disproportionated rosin and hydrogenated rosin. The heat medium according to claim 1 or 2, wherein the alcohol is at least one selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol and tert-butanol. oil. The rosin esters have an acid value of 2.0 mgKOH / g or less, a viscosity at 40 ° C. of 2000 mPa · s or less, a boiling point of 300 ° C. or more, a flash point of 150 ° C. or more, and a thermal conductivity at 150 ° C. of 0.11 W. The heat medium oil according to any one of claims 1 to 3, wherein the heat medium oil is at least / m · K. The heat medium oil according to any one of claims 1 to 4, wherein a content of rosins in the rosin esters is 50 to 90% by weight.