JPS6225128A - Silicone fluid - Google Patents

Abstract

PURPOSE:To provide a silicone fluid composed of a specific diorganopolysiloxane and having excellent low-temperature fluidity. CONSTITUTION:The objective silicone fluid of formula I [R<1> is 1-8C alkyl, etc.; R<2> is group of formula II (Q is hydrocarbon group; l is 3-6); n<=50] can be produced by (1) polymerizing divinyl tetramethyl disiloxane and octamethyl cyclotetrasiloxane in the presence of a catalyst (e.g. potassium hydroxide) to obtain alpha,omega-vinyldimethyl polysiloxane (component A), (2) separately mixing e.g. hexamethyl cyclotrisiloxane with dichlorodimethyl silane, reacting the compounds with each other in the presence of a catalyst (e.g. hexamethyl phosphamide), and hydrolyzing and neutralizing the reaction product to obtain a cyclic diorganopolysiloxane (component B), (3) adding the component B dropwise to the component A at room temperature in the presence of platinum catalyst, (4) reacting preferably at 110 deg.C under agitation, and (5) removing the low-volatile component.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a silicone fluid, and special feature C: refers to a silicone fluid with excellent low-temperature flow characteristics, in which both ends of the molecular chain are blocked with cyclic diorganopolysiloxitin. (This is related to two things.

(Prior Art) It is well known that dimethyl silicone oil has a smaller temperature coefficient and better low-temperature flow characteristics than various vegetable oils, animal oils, mineral oils, etc. g dimethylpolysilochitin units of this
It is also known that compounds into which a phenyl group, a fluoropropyl group, an isobutyl group, etc., or a C-branched structure in the molecule exhibit better low-temperature fluidity.

However, dimethylpolysilochitin units (C), which have a small amount of organic group introduced to improve low-temperature fluidity, have a larger temperature coefficient than dimethylsilicone oil, so their properties are intermediate between mineral oil and dimethylsilicone oil. rank.

Therefore, it is desired that this type of silicone oil has a temperature coefficient equivalent to that of dimethyl silicone and can be used as an oil even at -100''C.

(Structure of the Invention) The present invention relates to a silicone fluid C2 with excellent low-temperature flow characteristics that can meet such demands C2, which has a general formula [wherein the number of carbon atoms is 1 to 8]. The same or different groups selected from alkyl groups, vinyl groups, phenyl groups, and fluoroalkyl groups having 3 to 10 carbon atoms.

is a divalent hydrocarbon group, a heteroatom-containing divalent hydrocarbon group,
t is an integer of 3 to 6) and n is an integer of 50 or less.

That is, 1. The present inventors conducted various studies on organopolysiloxanes that do not crystallize and exhibit fluidity even at -501: 1. If both ends of a normal organopolysiloxane are capped with cyclic diorganopolysiloxy groups, this crystal can be obtained. He discovered that it was possible to lower the temperature at which oxidation occurred and proceeded with research on this topic.

This cyclic diorganopolysiloxane is represented by R''
, Q is the same as ε), and the fluid has a degree of polymerization of 50 or less.

Since this material has no crystallization point or melting point, its low-temperature properties can be significantly improved.
The present invention was completed by confirming that this material exhibits excellent flow characteristics even at -100°C.

The organopolysiloxane forming the silicone moving body of the present invention can be obtained by substituting the terminal group of a conventional diorganopolysiloxane with the above-mentioned cyclic diorganopolysiloxy group. The siloxane is preferably one in which both ends of the molecular chain are blocked with vinyl groups and the degree of monopolymerization is 50 or less, including α.

An example is ω-vinyldimethylpolysiloxane.

This α,ω-vinyldimethylpolysiloxane is shown by, which is composed of divinyltetramethyldisiloxane OH,OH8 and octamethylcyclotetrasiloxane OH,＼,OH
8. By blending the desired polysiloxane so that the degree of polymerization is 50 or less, adding an alkali such as caustic potash or an acid such as sulfuric acid, trifluoromethanesulfonic acid, etc. as a catalyst and causing an equilibration reaction. Obtainable.

The silicone fluid of the present invention is obtained by substituting the terminal vinyl group of this α,ω-vinyldimethylpolysiloxane with a cyclic diorganopolysiloxy group. Polysiloxane.

For example, heptamethylcyclotetrasiloxane is produced by mixing hexamethylcyclotrisiloxane and dichlorodimethylsilane (CI(,)2Sin/) in equimolar amounts, processing hexamethylphosphorus as a catalyst, and stirring at room temperature for 2 hours to produce 1.4- If dichlorohebutamethyltetrasiloxane is synthesized, hydrolyzed, neutralized with sodium bicarbonate, and purified by distillation, it can be obtained in a yield of 40 to 50%.

The substitution of vinyl groups with this cyclic diorganopolysiloxane is achieved by adding a platinum catalyst to the α,ω-vinyldimethylborosiloxane represented by the above formula (3), and then replacing the vinyl group with the chain formula (4).
) is added dropwise at room temperature and stirred at 110°C to react. After the reaction is complete, stripping to remove low volatile matter results in a reaction represented by the linear formula % formula %). An organopolysiloxane whose molecular chain ends are capped with a cyclic dimethylpolysiloxy group is used. This organopolysiloxane can also be produced by the condensation of dimethylpolysiloxane represented by the following formula (4), in which both ends of the molecular chain are blocked with hydroxyl groups, and pentamethylcyclotetrasiloxane represented by the above-mentioned formula (4). They meet by scattering as a formula.

The silicone fluid of the present invention is mainly composed of an organopolysiloxane obtained by the method described above and whose molecular chain terminals are capped with a cyclic diorganopolysiloxy group and whose degree of polymerization is 50 or less. Various polysiloxanes are used depending on the type of R3 in the above-mentioned general formula (1), and the following are representative examples thereof.

CB0m≦50] (n≦50) Furthermore, the above-mentioned organopolysiloxane whose molecular chain terminals are blocked with a cyclic diorganopolysiloxy group and whose degree of bipolymerization is 50 or less does not have a melting point or a crystalline point, Since it exhibits good low-temperature flow properties down to temperatures as low as the glass transition point, it is said to be useful as a lubricating oil and working oil in cold regions, and can also be used as a base oil for low-temperature greases.

Next, examples of the present invention will be given, and parts in each example indicate parts by weight.

Examples 1-3. Comparative Examples 1 to 2 1.10% potassium siliconate was added to 1 part of 3-divinyltetramethyldisiloxane and 20 to 60 parts of octamethylcyclotetrasiloxane at $1/KOH=50,
1:000 and heated and stirred at 160°C for 8 hours to polymerize (
equilibrium reaction).

It was neutralized with vinyldimethylchlorosilane in a molar amount 1.5 times that of KOH and 1.3-divinyltetramethyldisilazane in a 9 times weight part of this chlorosilane.

After stripping at 180℃,
, 1 times molar amount of hebutamethylcyclotetrasiloxane was added dropwise at room temperature, and chloroplatinic acid (1 ppm) was used as a catalyst.
An addition reaction was carried out at 10° C., and then the low volatile components were removed by IJ bubbling, and the organosiloxane shown by - was obtained.

When the physical properties of this were investigated, the following results were obtained based on the n value shown in Table 1 of FIG.

Table 1 shows the glass transition temperature of the silicone oil obtained above,
Crystallization temperature - Melting point measured using a differential calorimeter DSO (Seifu Electronics Co., Ltd. 1M product name).
Crystals as shown in the table were obtained, and for comparison, the measured values for those having a degree of polymerization (n) of 50 or more and for ordinary dimethylpolysiloxane are also shown.

In addition, from this result, the molecular chain terminals shown in Examples 1 to 3 were blocked with a cyclic diorganopolysiloxy group, and the monopolymerization degree was 5.
It was confirmed that silicone oil with a polymerization degree of 0 or less has no melting point or crystallization point and has excellent low-temperature properties compared to oils with a polymerization degree of 50 or more and dimethylpolysiloxane.

Table 2 also shows examples 2.3. When the viscosity-temperature dependence of the silicone oil of Comparative Example 2 was measured using a rheopexi analyzer (manufactured by Iwamoto Shinsakusho), the results shown in Table 3 (1) were obtained. It was confirmed that silicone oil No. 2-3 exhibits fluidity up to -100°C.

Patent applicant (M-Etsu Chemical Industry Co., Ltd. (LuQ,’a-”II

Claims (1)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ [Here, R^1 is an alkyl group having 1 to 8 carbon atoms, a vinyl group, a phenyl group, or a Same or different groups selected from fluoroalkyl groups, R^2 is a formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (here, Q is a divalent hydrocarbon group, a hetero atom-containing divalent hydrocarbon group, l is an integer of 3 to 6), n is 50
A silicone fluid characterized by being mainly composed of a diorganopolysiloxane represented by the following integer. 2. The silicone fluid according to claim 1, wherein R^2 is a cyclic dimethylpolysiloxane represented by the formula ▲ Numerical formula, chemical formula, table, etc. ▼. 3. Claim 1 in which all R^1s are methyl groups
The silicone fluid described in Section 1.