JP2630865B2 - Silicone oil with excellent heat resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silicone oil comprising an organopolysiloxane having a mercaptoalkyl group.

[0002]

2. Description of the Related Art Conventionally, silicone oil represented by dimethylpolysiloxane has properties such as excellent heat resistance and cold resistance, small change in viscosity with temperature, and small surface tension. Utilizing such characteristics, it is widely used for applications such as release agents, lubricating oils, and hydraulic oils. As such a silicone oil, a mercapto group-containing organopolysiloxane has been proposed (see JP-A-61-236875, JP-A-61-268757, etc.).

[0003]

However, the above-mentioned mercapto group-containing organopolysiloxane has poor heat resistance under severe temperature conditions as compared with generally used dimethylorganopolysiloxane, and is deteriorated by thermal oxidation. However, there is a problem that gelation, discoloration, odor and the like are generated. Therefore, these uses have been limited to those at relatively low temperatures, such as for wax and fiber surface treatment. In addition, regarding the use as a release agent, recently, high release properties have been required especially for high-functional materials such as silicone rubber, fluorine rubber, and various engineering plastics. However, such a demand was not sufficiently satisfied. Therefore, the object of the present invention is excellent in heat resistance,
Another object of the present invention is to provide a silicone oil comprising an organopolysiloxane having a mercaptoalkyl group, which has a high release property and is particularly effectively used for a release agent.

[0004]

According to the present invention, in the following general unit formula, (R ¹ SH) _a R ² _b SiO _{(4-ab) / 2} , wherein R ¹ has 1 to 8 carbon atoms. Alkylene group of R ²
Is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, a is a number of 0.0001 to 0.01, and b is 1.95 ≦ a +
is a number satisfying b ≦ 2.20, in expressed, and, and the mercaptoalkyl group (R ¹ SH) in a proportion of 0.01 to 1 mol% per total side chain groups bonded to the silicon atoms, 25
A silicone oil is provided which comprises an organopolysiloxane having a viscosity at 10 ° C of 10 to 100,000 cSt.

That is, the present invention has excellent heat resistance and a lower surface tension than ordinary dimethylorganopolysiloxane by setting the content of a specific mercaptoalkyl group in a very limited range. It succeeded in obtaining silicone oil. Since the silicone oil has a low surface tension, it is particularly effectively used as a release agent having a high release property.

In the above general formula, an alkylene group R
The ^1, can be exemplified alkylene group having 1 to 8 carbon atoms from methylene to octamethylene,
Particularly preferred is a trimethylene group. As the monovalent hydrocarbon group R ² having 1 to 8 carbon atoms, a methyl group,
Alkyl groups such as ethyl group, propyl group, butyl group, pentyl group and hexyl group, cycloalkyl groups such as cyclopentyl group and cyclohexyl group, aryl groups such as phenyl group and naphthyl group, trifluoropropyl group, nonafluorohexyl group and the like And these groups contained in the molecule bonded to the silicon atom may be the same or different from each other. In the present invention, a methyl group is particularly preferred.

Further, a and b are each 0.0001 ≦ a
≦ 0.01, 1.95 ≦ a + b ≦ 2.20. For example, if a is smaller than 0.0001, the surface tension with respect to silicone rubber, fluororubber or metal or metal oxide increases, and if a is larger than 0.01, , Heat resistance decreases.

Further, in the present invention, the content of the mercaptoalkyl group (R ¹ SH) is 0.01 to 1 mol%, particularly 0.1 mol%.
It is important to be in the range of 05-0.4 mol%. If this exceeds 1 mol%, the heat resistance will be reduced, and disadvantages such as gelation will occur under high temperature conditions. On the other hand, if it is lower than 0.01 mol%, the heat resistance decreases and the surface tension increases.

Further, the above-mentioned organopolysiloxane has a viscosity at 25 ° C. of 10 to 100,000 cSt, particularly preferably.
It is in the range of 100 to 10,000 cSt. When the viscosity is lower than 10 cSt, since a large amount of volatile components is contained, these components volatilize when used at a high temperature, so that an excellent effect cannot be exhibited for a long time. On the other hand, if the viscosity is higher than 100,000 cSt, the extensibility becomes poor, so that, for example, the initial release property when used as a release agent is reduced.

The organopolysiloxane represented by the above-mentioned general unit formula may have any of a straight-chain, branched and cyclic structure, but a straight-chain structure is generally preferred. Among these organopolysiloxanes, the most preferable one is represented by, for example, the following average formula (1).

[0011]

Embedded image

In the above formula, m is a number from 8 to 1500, and n is
It is a number from 0.002 to 30. The above-mentioned organopolysiloxane can be produced by a method known per se, for example, trimethylsiloxy-terminated polydimethylsiloxane,
Easy production by using octamethylcyclotetrasiloxane and methylmercaptopropylpolysiloxane as raw materials, conducting polymerization at a high temperature using a basic catalyst, and removing low-molecular-weight siloxane by N ₂ -substitution high-temperature vacuum stripping. Can be.

The silicone oil of the present invention comprising the above-mentioned organopolysiloxane is particularly effective as a mold release agent, a lubricating oil, etc., alone or as a solution dissolved in a suitable organic solvent, or in the form of an emulsion. used. Of course, this silicone oil can be used in combination with a conventionally known dimethyl silicone oil or the like, depending on the application.

[0014]

EXAMPLES Examples 1 and 2 and Comparative Examples 1 and 2 As test oils, the following mercapto-containing organopolysiloxanes (A) to (C) and dimethylpolysiloxane (D) were synthesized by known methods. It was used. (A): Example 1 The following average composition formula (2)

Embedded image An organopolysiloxane having a mercaptopropyl group content of 0.23 mol% and a viscosity at 25 ° C. of 290 cSt. (B): Example 2 The following average composition formula (3)

Embedded image And the mercaptopropyl group content is 0.076 mol%
And an organopolysiloxane having a viscosity of 310 cSt at 25 ° C. (C): Comparative Example 1 Average composition formula (4) below

Embedded image An organopolysiloxane having a mercaptopropyl group content of 1.9 mol% and a viscosity at 25 ° C. of 330 cSt. (D): Comparative Example 2 The following average composition formula (5)

Embedded image A dimethylpolysiloxane having a viscosity of 335 cSt at 25 ° C.

For the organopolysiloxanes (A) to (D), the surface tension was measured using a CBVP surface tensiometer (manufactured by Kyowa Kagaku Co., Ltd.), and the contact angle with Teflon was measured using a contact angle meter (Kyowa Kagaku). (Manufactured by Co., Ltd.).
The results are shown in Table 1. In addition, 25 g of each of (A) to (D) is a clean 100 ml hard glass beaker (inner diameter 51 mm, depth 73 m
m), leave it in a hot air circulating thermostat at 200 ° C,
The change in viscosity was measured. Table 2 shows the results.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

The silicone oil of the present invention has excellent heat resistance and extremely high releasability.
Therefore, this silicone oil is extremely useful as a release agent.

Claims (1)

(57) [Claims] 1. The following general unit formula: (R ¹ SH) _a R ² _b SiO
_{(4-ab) / 2 In the} formula, R ¹ is an alkylene group having 1 to 8 carbon atoms, R ² is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and a is 0.0001 to Is a number of 0.01 and b is
1.95 ≦ a + b ≦ 2.20, wherein the mercaptoalkyl group (R ¹ SH) is contained at a ratio of 0.01 to 1 mol% based on all side chain groups bonded to silicon atoms. A silicone oil comprising an organopolysiloxane having a viscosity at 25 ° C. of 10 to 100,000 cSt.