JPH0517741A - Thermal medium composition - Google Patents

Abstract

PURPOSE:To provide the subject composition containing a benzyl biphenyl fraction and a dibenzyl toluene oil in specific amounts, respectively, having high heat resistance and a low pour point in spite of having a high boiling point, and having a high ignition point. CONSTITUTION:The objective composition comprises 10-90 pts.wt. of a benzyl biphenyl fraction comprising a mixture of ortho, meta and para-benzyl phenyl isomers [the ratio of the para isomer is <=60wt.% (preferably <=50wt.%)] and 90-10 pts.wt. of a dibenzyl toluene oil and has a pour point of <=0 deg.C.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat carrier composition.

[0002]

2. Description of the Related Art A heating medium is desired to have a high boiling point and heat resistance when used at a high temperature, but it is desired to maintain a liquid state even when the apparatus is stopped. As a heat medium having such characteristics, an aromatic hydrocarbon heat medium having excellent thermal stability is known, and in particular, many reports have been made on the biphenyl heat medium because of its excellent performance. U.S. Pat. No. 1,882,809 teaches a heat carrier composition composed of biphenyl and diphenyl ether, and U.S. Pat. No. 3,931,028 discloses a heat carrier composition further containing alkyl biphenyls. I ’m teaching
JP-A-49-104,890 teaches a heat carrier composition consisting of a benzylbiphenyl mixture. And
From the standpoint of preventing accidents such as fires, it is desirable that the flash point be high. From this point of view, the heat medium is 320 ° C.
It is desirable that it be durable against the above long-term use, maintain its fluidity even in the cold season when it becomes 0 ° C. or lower, and have a flash point of 200 ° C. or higher, more preferably economically available.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel heat carrier composition having high heat resistance, a high boiling point, a low pour point and a high flash point.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have found that when a specific benzylbiphenyl compound is added to dibenzyltoluene, which is a commercially available heat carrier, an excellent heat carrier composition satisfying the above can be obtained. Completed the invention. This heat transfer medium composition is a heat transfer medium composition comprising 10 to 90 parts by weight of a benzyl biphenyl fraction and 90 to 10 parts by weight of dibedyl toluene oil, and having a pour point of 0 ° C. or lower.

As the dibenzyltoluene oil which is one component of the present invention, a commercially available dibenzyltoluene heat carrier can be used. It is usually a mixture of dibenzyltoluene isomers, optionally containing reaction byproducts with similar boiling points, and has a boiling range of about 380-400 ° C. Examples of such dibenzyltoluene oil include Soken Chemical's NeoSK-OIL 1400 (trade name) and Hüls' Marotherm S, which have a pour point of -28 ° C,
Viscosity (25 ℃) 39cp, Flash point 208 ℃, 5vol%
Distillation temperature 388 ° C, and 95 vol% distillation temperature 396 ° C
It has the following physical properties. Although this value is somewhat different depending on the production conditions, distillation conditions, etc., it can be similarly used as long as it is mainly dibenzyltoluene.

The other component of the present invention is a benzylbiphenyl fraction, preferably a benzylbiphenyl fraction in which the proportion of para-form in benzylbiphenyl is 50% by weight or less. This is obtained by distilling a reaction mixture obtained by reacting biphenyl with a benzylating agent such as benzyl chloride in the presence of a Lewis acid such as aluminum chloride or a solid acid catalyst such as silica-alumina, and taking out benzyl biphenyls. To be Further, the obtained benzylbiphenyl fraction is produced in a proportion of 70% by weight or more of the para body, but since this para body has a high melting point, the para body is used when the pour point needs to be lowered. Is 60% by weight or less, preferably 50% by weight or less, and more preferably 35% by weight or less. To reduce the proportion of para bodies, use ethanol
Recrystallization performed using a solvent such as a solvent or a crystallization method in which crystallization is performed by cooling is suitable. In this way, the benzylbiphenyl fraction in which the proportion of the para body in the benzylbiphenyl is 50% by weight or less is a benzylbiphenyl isomer mixture consisting of metabenzylbiphenyl, orthobenzylbiphenyl and parabenzylbiphenyl, and in some cases, It includes reaction byproducts with similar boiling points and has a boiling range of about 360-400 ° C. As an example, the benzylbiphenyl fraction whose para-form content has been reduced to 25% by weight by the recrystallization method contains 41% by weight of metabenzylbiphenyl and 16% by weight of orthobenzylbiphenyl.
It has physical properties such as a freezing point of 23 ° C., a viscosity (25 ° C.) of 29 cp, a 5 vol% distillation temperature of 374 ° C., and a 95 vol% distillation temperature of 388 ° C. Although this value may fluctuate to some extent depending on the production conditions, distillation conditions, etc., as long as it is a fraction mainly containing benzylbiphenyl, it can be similarly used. Moreover, even if the para body is contained in an amount of 60% by weight or more,
By adjusting the blending ratio with dibenzyltoluene oil, the pour point can be set to 0 ° C. or lower, so it is not necessary to reduce the ratio of the para form, but rather to improve the flash point and heat resistance. It is advantageous to have more.

The proportion of the benzyl biphenyl fraction and dibenzyltoluene oil is 10 to 90% by weight, preferably 30 to 70% by weight, and 90 to 10% by weight, preferably 70 to 30% by weight, for the latter. And the pour point is 0 ° C. or lower, preferably −10 ° C. or lower. The pour point can be lowered by increasing the proportion of dibenzyltoluene or decreasing the content of parabenzylbiphenyl in the benzylbiphenyl fraction.

[0008]

【Example】

Example 1 A catalyst was separated from the reaction mixture obtained by reacting biphenyl with benzyl chloride in the presence of an aluminum chloride catalyst, and then distilled to obtain a benzyl biphenyl fraction. this. The content of purified parabenzyl biphenyl and parabenzyl biphenyl after purification by recrystallization with ethanol was 25
Benzyl biphenyl fraction (BBP fraction) which became weight%
Got This BBP fraction is metabenzyl biphenyl 4
1% by weight, orthobenzylbiphenyl 16% by weight, intermediate component 4% by weight of orthobenzylbiphenyl and metabenzylbiphenyl, intermediate component 5% by weight of metabenzylbiphenyl and parabenzylbiphenyl, component 9% by weight having a higher boiling point than parabenzylbiphenyl Including freezing point 23 ° C., viscosity (25 ° C.) 29 cp, 5 vol% distillation temperature 374 ° C.,
95vol% distillation temperature 388 ° C, specific gravity (25 ° C) 1.0
It has the property of 63.

Dibenzyltoluene oil (DBT oil)
Has a molecular weight of 270, a pour point of -28 ° C, and a viscosity of (25
℃) 39cp, flash point 208 ℃, 5vol% distillation temperature 3
88 ° C, 95 vol% distillation temperature 396 ° C, specific gravity (25
(° C.) 1.034 commercial product was used.

Both were mixed at a ratio of 1: 1 (weight ratio) to obtain a heat medium composition. This has a pour point of −28 ° C., a viscosity (25 ° C.) of 34 cp, a flash point of 200 ° C., a 5 vol% distillation temperature of 380 ° C., a 95 vol% distillation temperature of 392 ° C., and a specific gravity (25 ° C.) of 1.048. A thermal stability test was performed. In the thermal stability test, 1,000 ml of autoclave (made by SUS316) was charged with 500 ml of the heat medium composition, and the atmosphere was 7 at 320 ° C., a nitrogen atmosphere, a rotation speed of 140 rpm.
It was carried out under the condition of holding for 20 hours. Also, for comparison DB
Also done for T oil. Table 1 shows the physical properties and pressure changes after the thermal stability test.

[0011]

[Table 1]

The BBP fraction and DBT oil were blended in a weight ratio of 70:30, 50:50 and 30:70, and the pour points of the respective compounds were measured. DBT oil alone was -28 ° C. 70:30 mixture-26 ° C, 50:50 mixture-28 ° C and 30:70 mixture-27 ° C.

[0013]

EFFECTS OF THE INVENTION The heat carrier composition of the present invention not only has good thermal stability but also has a low pour point and a high flash point. It can be advantageously used as a medium.

Claims (2)

[Claims] 1. A composition comprising 10 to 90 parts by weight of a benzyl biphenyl fraction and 90 to 10 parts by weight of dibedyl toluene oil,
A heat medium composition having a pour point of 0 ° C. or lower. 2. The heat carrier composition according to claim 1, wherein the benzylbiphenyl fraction is a benzylbiphenyl fraction in which the proportion of para form in benzylbiphenyl is 60% by weight or less.