JPH03135761A - Quartz glass capillary column - Google Patents

Abstract

PURPOSE:To obtain the quartz glass capillary column which does not easily break during handling even in the case of processing for a long period of time at a high temp. or repetitive use by coating the outside surface of the quartz glass capillary column with a carbon film and further coating the surface thereof with a metallic film. CONSTITUTION:An anhydrous synthesized quartz glass tube is softened by a drawing furnace kept at about 2,000 deg.C and is stretched to the quartz glass capillary 1 of a prescribed inside diameter and outside diameter. The capillary 1 is fed into a quartz muffle in a heating furnace kept at about 1,200 deg.C right after the stretching and gaseous nitrogen flow contg. benzene is supplied into the furnace to thermally decompose the benzene and to form the carbon film 4 on the surface of the capillary 1. Further, the capillary is passed in molten aluminum to form the metallic film 5 thereon. The capillary is cut to a prescribed length and a thin-film stationary phase 2 of polydimethyl siloxane is formed on the inside surface. The metal may be Zn, Ti, Sn or Bi. Then, the carbon film 4 acts as a buffer layer and the generation of partial deviation and peeling at the boundary with the quartz glass do not arise even if a heat history is applied thereto. The effect of the protective film against the breakage is thus maintained and the excellent heat resistance is exhibited.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to fused silica capillary columns.

In particular, it relates to a quartz glass capillary column whose outer surface is coated with a heat-resistant protective film.

[Conventional technology]

Quartz glass capillary columns are used in gas chromatography,
liquid chromatography, supercritical fluid chromatography,
It is useful as a separation column for ion chromatography, electrophoretic analysis, etc. Columns using silica glass capillaries have superior properties compared to conventional packed columns and columns using metals such as SUS stainless steel or multi-component glass capillaries, and further development is expected in the future. A quartz glass capillary column has superior separation performance compared to, for example, a packed column, and has fewer impurities, so it has the advantage of less tailing due to adsorption than a column using a capillary made of metal or multi-component glass.

Fused silica capillaries usually have an outer diameter of 0.2 to 1.5
The marks are thin with a thickness of about 0.05 to 0.2 mm, and since quartz glass has poor flexibility, it easily breaks due to excessive external force. In particular, if there are scratches on the surface, it is likely to break at that location. Therefore, by providing a protective film on the outer surface of the quartz glass capillary, it increases the strength against breakage.
At the same time, it protects against wear and moisture.

FIG. 2 shows an example of a cross section of a conventional quartz glass capillary for gas chromatography. 2 is a quartz glass capillary, 2 is a stationary phase, and 3 is a heat-resistant protective film. As will be described later, the heat-resistant protective film has conventionally been made of heat-resistant resin such as polyimide resin or metal such as aluminum.

To manufacture such a quartz glass capillary column, first, an anhydrous synthesized quartz glass base material is heated to a temperature of about 2000 ml.
A quartz glass capillary 1 is drawn thinly in a drawing furnace at ℃.
A heat-resistant protective film 3 is immediately coated after stretching. After cutting the quartz glass tube 1 to an appropriate length and subjecting the inner surface of the quartz glass tube 1 to surface treatment with a silane coupling agent or the like, a stationary phase 2 made of silicone (eg, polydimethylsiloxane), polyethylene glycol, etc. is formed.

The above surface treatment is for inactivating the hydroxyl groups present on the glass surface, and is performed at a high temperature, for example at 40'C.
A process of more than 10 hours is often used. Furthermore, when a completed silica glass capillary column is used in gas chromatography, it is often used at a high temperature of about 350° C. depending on the purpose of analysis. Therefore, the heat-resistant protective film is 3
It must be able to withstand high temperatures of 50°C or higher.

Conventional heat-resistant protective films for fused silica capillary columns include
Polyimide resin (for example, Japanese Patent Publication No. 62-36537,
(Refer to JP-A-61-68561), metals such as aluminum, etc. are used.

Polyimide resins conventionally used as heat-resistant protective films are usually aromatic polyimides, such as Trenise #200.
0. #3000 (manufactured by Toshi Co., Ltd.), etc.

The aluminum coating is applied by passing a heated drawn quartz glass capillary through molten aluminum filled in a die.

[Problem to be solved by the invention]

However, among the above-mentioned heat-resistant protective films, polyimide resin has weak adhesion to quartz glass and deteriorates and becomes brittle when left at a high temperature of about 400° C. for a long time.

Therefore, the surface treatment of the inner surface of the capillary before the formation of the stationary phase deteriorates it and makes it brittle, and if the completed column is used repeatedly at high temperatures, the protective film will peel off from the quartz glass capillary, making the column more likely to break.

Because the difference in thermal expansion coefficient between aluminum coating and quartz glass is extremely large (silica glass 5.7 x 10-' de
g-', aluminum 2.3X10-'deg
-') When the capillary is subjected to thermal history, scratches occur on the capillary surface due to displacement or peeling at the interface between the quartz glass and the aluminum film, and the bending strength of the capillary decreases significantly.

Furthermore, when a quartz glass capillary is passed through molten aluminum at a temperature of 660°C or higher, the outer surface of the capillary may be damaged due to contact with the fine aluminum grains that are mixed in with it. The problem was that it easily broke when wrapped. A decrease in yield due to breakage during the manufacturing process has increased the manufacturing cost of capillary columns.

Therefore, an object of the present invention is to provide a silica glass capillary column that does not easily break during handling even when subjected to long-term processing or repeated use at high temperatures of 350° C. or higher.

Another object of the present invention is to provide a fused silica capillary column that does not easily break when wound into a coil, reducing manufacturing costs.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a quartz glass capillary column having a stationary phase on the inner surface of the quartz glass capillary and a heat-resistant protective film on the outer surface. The outer surface of the quartz glass capillary is coated with a carbon film, and the outer surface of the capillary is further coated with a metal film.The carbon film is provided in direct contact with the outer surface of the quartz glass capillary.

The quartz glass capillary column having a heat-resistant protective film of the present invention consists of the following elements.

(1) Quartz glass capillary (2) Stationary phase formed on the inner surface of the quartz glass capillary (3) Carbon coating formed on the outer surface of the silica glass capillary (4) Metal coating provided on the outside of the carbon coating Below is a description of each element. explain in detail.

(1) Quartz glass capillary Usually, a capillary with an inner diameter of 0.05 to 1.0 mm and a thickness of about 0.05 to 0', 2+ nm is used. As usual, a relatively thick quartz glass tube made of anhydrous material is heated at a temperature of about 2
It can be made by thinly drawing it in a drawing furnace at 000°C.

(2) Stationary phase formed on the inner surface of the quartz glass capillary Since the quartz glass capillary column of the present invention is used for gas chromatography, a stationary phase is formed on the inner surface of the quartz glass capillary. To form the stationary phase, a solution of the stationary phase forming substance is passed through a quartz glass capillary whose inner surface has been previously inactivated, and then an appropriate inert gas is passed through the capillary to evaporate the solvent (dynamic method). There is a method (static method) in which an inactivated quartz capillary is filled with a solution of a stationary phase forming substance and then the solvent is sequentially heated and evaporated from one end.

The deactivation treatment on the inner surface of the quartz capillary is to deactivate the hydroxyl groups present on the glass surface, and can be performed by treatment at a high temperature (for example, 400'C) for more than 10 hours in the presence of a silane coupling agent. .

Stationary phase forming substances include, for example, polydimethylsiloxane,
Siloxanes such as polyphenylmethylsiloxane, polyethylene glycol, etc. can be used.

For example, methylene chloride, n-pentane, acetone, diethyl ether, etc. can be used as the solvent.

(3) Carbon coating formed on the outer surface of the quartz glass capillary A carbon coating is provided on the outer surface of the quartz glass capillary.

The carbon film used in the present invention can be formed by thermal decomposition of an organic substance, for example, a hydrocarbon with a large carbon content. For example, a nitrogen gas flow containing benzene is supplied into the heating furnace to thermally decompose the benzene, and a carbon layer is formed on the surface of the quartz fiber passing through the heating furnace.

The thickness of the carbon film is usually about 200 Å or more, about 1000 Å thick.
A value of Å or less is appropriate.

(4) Metal coating provided on the outside of the carbon coating A metal coating is provided on the carbon coating on the outside of the quartz glass capillary.

Suitable metals constituting the metal coating include, for example, aluminum, indium, titanium, tin, bismuth, and the like. Aluminum and titanium are preferred.

The metal coating can be formed by passing a heated and stretched quartz glass capillary through molten metal filled in a die. The metal coating may be formed by electroplating in a metal salt solution using the carbon coating as a cathode.

The thickness of the metal coating is usually approximately 10 μm or more and 20 μm or less.

The quartz glass capillary column of the present invention is useful not only in gas chromatography but also as a separation column in liquid chromatography, supercritical fluid chromatography, ion chromatography, and the like.

[Effect]

The heat-resistant protective film of the quartz glass capillary column of the present invention has a metal coating provided on the quartz glass via a carbon layer, so it is much more effective against the glass capillary than when a metal coating is used alone. Has excellent adhesion. Even if the difference in thermal expansion coefficient between the metal coating and quartz glass is large, the carbon coating interposed between the two acts as a buffer layer, so even if thermal history is applied, the coating will not partially shift at the interface with the quartz glass. Unlike the case where a quartz glass capillary is directly coated with metal, the effect of the protective film against breakage is maintained. As a result, it exhibits better heat resistance than when a metal film is used alone as a protective film. That is, the thin fused silica capillary is protected against bending and does not break easily, even when subjected to repeated thermal history at high temperatures during handling during manufacturing and use as a column.

Furthermore, according to the present invention, even if the quartz capillary is passed through molten metal to apply a metal coating, the surface of the quartz capillary will not be damaged due to the carbon coating. It never breaks.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Example 1] An anhydrous synthetic quartz glass tube was softened in a drawing furnace at a temperature of about 2000°C, and had an inner diameter of 0.35 mm and an outer diameter of 0.45+n.
m quartz capillary. Immediately after stretching, the outer surface of the quartz capillary was coated with carbon and metal as described below, and a stationary phase was further provided on the inner surface to obtain a quartz glass capillary column having the cross section shown in FIG. 1 is a quartz glass capillary, 2 is a stationary phase, 4 is a carbon film,
5 is a metal coating further provided thereon.

In a heating furnace at a temperature of 1200°C, the outer diameter is 20 mm and the inner diameter is 16 mm.
A quartz fiber is fed from above into a quartz pine full of mm size, and while nitrogen gas is supplied from the nitrogen gas supply port provided at the top of the quartz pine full, nitrogen gas containing benzene is supplied from the mixed gas supply port provided at the center of the quartz pine full. An air flow was supplied to thermally decompose the benzene and form a carbon layer with a thickness of about 500 nm on the surface of the quartz fiber.

Carbon coating followed by quartz capillary at 660°C.
It was passed through molten aluminum and coated with aluminum with a thickness of 15 μm by the dip method.

A 100mm long quartz capillary coated with a heat-resistant protective film
The inner surface of the quartz capillary was silylated by a conventional method to form a thin film of polydimethylsiloxane on the inner surface.

The quartz glass gear pillar column obtained in this way was
When the capillary was wound around a 0 mm mandrel and placed in a constant temperature bath maintained at a temperature of 500''C for 30 minutes, no breakage of the capillary was observed.

When wrapped around a mandrel, the temperature ranges from -80°C to 50°C.
After 10 heat cycles at 0°C, the capillary column was subjected to a bending strength test.

The probability of breakage at a bending diameter of 20 mm was 0%.

[Comparative Example 1] In Example 1, the carbon coating was omitted, and the outer surface of the quartz glass was directly coated with aluminum.

The film thickness was 15 μm. A stationary phase was formed on the inner surface of the quartz tube in the same manner as in Example 1.

The obtained quartz glass capillary column was wound around a mandrel with an outer diameter of 20 mm, and the temperature was adjusted from -80°C to 500°C.
A bending strength test was conducted after 10 cycles between the two. The probability of breakage at a bending diameter of 50 mm was 50%, and the probability of breakage at a bending diameter of 20mm was 100%.

[Comparative Example 2] A quartz capillary was stretched in the same manner as in Example 1, and immediately after stretching, the outer surface of the quartz capillary was coated with a polyimide protective film in the following manner. The cross section of the resulting capillary column is as shown in FIG.

Pyromellitic dianhydride and 3,
An N-methylpyrrolidone solution containing 25% of polyamic acid obtained by the reaction of 3"-diaminodiphenyl ether was applied, and dried and cured in an electric furnace at a temperature of 500"C to form a polyimide protective film with a thickness of 15 μm. I let it happen.

Next, in the same manner as in Example 1, a stationary phase was formed on the inner surface of the quartz capillary.

When the obtained quartz glass capillary column was wound around a mandrel with an outer diameter of 20 mm and placed in a constant temperature bath kept at a temperature of 350°C for 30 minutes, peeling of the protective layer was observed in some places on the capillary column. The capillary column was broken at that point.

〔Effect of the invention〕

In the capillary column of the present invention, the heat-resistant protective film on the outer surface of the silica glass capillary has sufficient mechanical strength,
It has excellent adhesion to quartz glass and does not deteriorate due to heat, so it easily breaks even under conditions where it is subjected to repeated thermal cycling at high temperatures during handling during production such as stationary phase formation and coil winding, and when used as a column. Never.

The heat resistance of the quartz glass capillary column according to the present invention is as follows:
Much superior to silica glass capillary columns with a single metal coating. Therefore, it does not break even when used repeatedly at high temperatures in gas chromatography.

The silica glass capillary column of the present invention does not have a decrease in yield due to bending when wound into a coil shape, and the manufacturing cost is reduced.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of a silica glass capillary column of the present invention. FIG. 2 is a cross-sectional view of a conventional silica glass capillary column. Explanation of symbols 1-1----- Quartz glass capillary 2----
----Stationary phase 3--------Heat-resistant protective film 4---Carbon coating 5----Metal coating--Quartz Cabilla・・・−Stationary phase・−・・−Heat resistant protective film Carbon coating・−Metal coating

Claims (2)

[Claims] (1) A quartz glass capillary column having a stationary phase on the inner surface of the quartz glass capillary and a heat-resistant protective film on the outer surface, the heat-resistant protective film comprising a carbon coating in contact with the outer surface of the silica glass capillary, and A quartz glass capillary column characterized by consisting of a metal coating provided on the outside. (2) The silica glass capillary column according to claim 1, wherein the metal coating is made of at least one metal selected from aluminum, indium, titanium, tin, or bismuth.