JPH02201157A - Quartz glass capillary - Google Patents

Abstract

PURPOSE:To obviate the generation of the thermal deterioration of the quartz glass capillary for gas chromatograph formed by applying a coating material consisting of a high-polymer material on an outer peripheral surface even if the capillary is subjected to a high-temp. treatment over a long period of time and to improve the resistance thereof to acids and alkalis by adopting polytitanocarbosilane to constitute the high-polymer material to constitute the coating layer of the above-mentioned capillary. CONSTITUTION:A quartz glass tube is drawn and the polytitanocarbosilane is used for the coating of the outer peripheral surface thereof. The unit expressed by the formula is used as the basic structural unit of the polytitanocarbosilane.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in silica glass capillaries used in gas chromatographs.

[Prior art] Silica glass is easy to stretch and is suitable for making capillaries, and it has less adsorption and contact effects than metals, so it is an excellent material for capillaries for gas chromatographs, and it is used as a material for gas chromatographs. quartz glass capillaries are becoming mainstream.

However, this quartz capillary easily breaks due to excessive stress, so the quartz glass tube was made into a capillary with a sufficiently small outer diameter by wire drawing, and the cross-sectional shape of the capillary 1 is shown in Fig. 3. A coating layer 2 is formed on the outer circumferential surface to increase the strength against gI breakage and to protect the surface from abrasion and moisture.

By the way, as a coating material for forming the coating layer 2 of the capillary 1, metals such as aluminum can be considered when used at temperatures above 350°C, but they have the disadvantage of poor acid resistance and require no equipment for coating. Conventionally, polyimide, which is a heat-resistant polymer material, has been used because it is complicated.

FIG. 4 is a schematic diagram of the drawing process of a quartz glass tube. A pretreated synthetic quartz glass tube 3 is melted and drawn in a drawing furnace 4 to form a capillary with an inner diameter of 250 μm and an outer diameter of 350 μm, and a die 5 is placed on the capillary. The film was coated with polyimide, the solvent was evaporated in a heating furnace 6, and the film was wound up in a winder 7.

[Problem to be solved by the invention] Active sites such as silanol groups exist on the inner glass surface of a quartz glass capillary, and this has an unfavorable effect on separation, so it is necessary to inactivate the silanol groups by silylation. becomes. The silanol groups present on the inner glass surface are acidic and participate in hydrogen bonding as proton-donating groups, forming hydroxyl groups, ether bonds, carbonyl groups,
Acts as an adsorption active site for compounds with amino groups, etc.

An effective method for blocking such silal groups and eliminating adsorption activity based on hydrogen bonds is silylation, in which HMDS (Iexametry) is added to the hydroxyl group of the silanol.
lene dlsllaxzane) and TPDMDS
(Tetrapheriyl former 5etbyl dis
llazane) etc. to form a silyl ether.

Here, when silylation is performed using HMDS or TPDMDS, silylation will be better if high temperature treatment is performed at 300 to 400° C. for 5 to 20 hours.

However, when the conventional polyimide-coated quartz glass cavity is subjected to the above-mentioned high-temperature treatment, even if the treatment atmosphere is an inert atmosphere such as N2 gas, thermal deterioration occurs and it becomes prone to breakage. The present invention solves the problem of the m point in the conventional technology, which often caused problems in handling, and does not cause thermal deterioration even if the inner glass surface of the quartz glass capillary is treated at high temperatures for a long time, and is acid resistant. The purpose of this study is to improve the performance of silica glass capillaries by using coating materials with excellent chemical resistance such as alkali resistance.

[Means for Solving the Problems] The present invention is characterized in that the polymeric material constituting the coating layer provided on the outer periphery of the quartz glass capillary is polytitanocarbosilane.

[Function] In the present invention, a quartz glass tube is drawn and polytitanocarbosilane is used to coat the outer peripheral surface of the tube, so the functional strength in the dispensing atmosphere is significantly improved compared to conventional polyimide. It is possible to perform inner surface treatment such as silylation at high temperatures for a long time, and the performance of the silica glass capillary can be improved.

[Example] In this example, in the manufacturing process of a silica glass capillary as shown in FIG. 4, polytitanocarbosilane dissolved in an organic solvent is coated on the outer peripheral surface of the capillary using a die 5 to form a coating layer. This is what I did.

The basic structural unit of polytitanocarbosilane is as shown in F.

CH30 -9i -0-T i -0- CH3 R: Cn H2n+1 Next, the thermal deterioration characteristics of the conventional example using polyimide for capillary coating and this example using polytitanocarbosilane are compared. Then, the result is as follows.

Figure 2 shows bending strength test data for a capillary according to a conventional example.
The samples were left to stand for 0 and 20 hours, and a bending strength test using a mandrel was conducted.

As is clear from FIG. 2, in the conventional example, the strength decreases significantly as the standing time increases.

FIG. 1 shows bending strength test data of the capillary according to this example.

The capillary according to this example was tested at 400° C. The results were exactly the same as the initial value, and there was no decrease in strength.

Tests were conducted at a temperature of 500° C. The results showed that the strength decreased slightly after 20 hours, but this was at a level that would pose no practical problem.

As described above, according to this example, the mechanical strength in high-temperature atmospheres is significantly improved compared to conventional polyimide coatings, and it can cope with long-term, high-temperature inner surface treatments such as silylation, and improves the performance of silica glass capillaries. ” You can plan the second. Furthermore, the coating material of this example is excellent not only in heat resistance but also in chemical resistance such as acid resistance and body alkalinity.

[Effects of the Invention] According to the present invention, the problems of the prior art are solved, and the
This can be achieved without thermal deterioration even during high-temperature treatment.

4゜n * iit explanation of drawings Figure 1 is bending strength test data of a quartz glass capillary according to an embodiment of the present invention, Figure 2 is bending strength test data of a quartz glass capillary according to a conventional example, and Figure 3 is a conventional example. FIG. 4 is a cross-sectional view of a quartz glass capillary shown in FIG.

1; capillary, 2: Gel covering layer.

(〃) army 4; Saka@@17-i (φ negative light) ”11 (φ Party Gap) 2: Drawing layer

Claims (1)

[Claims] 1. A quartz glass capillary for gas chromatography having a coating layer of a polymeric material formed on its outer peripheral surface, wherein the polymeric material constituting the coating layer is polytitanocarbosilane.