JPH0559195A - Treatment of inner surface of fluororesin tube - Google Patents

Abstract

PURPOSE:To uniformly treat the inner surface of a fluororesin tube while preventing the tube, e.g. from being bent by pouring a surface treating liquid into the fluororesin tube having a jammed part and vertically shifting the jammed part. CONSTITUTION:After (A) setting a jammed part to a fluororesin tube, e.g. by nipping the tube by using a pair of pinch rolls, pinch boards, etc., (B) a surface treating liquid (preferably liquid ammonia solution of alkaline metal such as sodium) is poured through the opening end of the tube and stored in the part higher than the jammed part. (C) The jammed part is then vertically shifted (Jammed part is moved downward preferably by moving tube upward while fixing pinch rolls, etc., constituting jammed part) to shift the contact part between the inner surface of the tube and the surface treating liquid, thus uniformly treating the inner surface of the tube with the surface treating liquid while preventing occurrence of bending, creasing, etc., causing lost of smoothness of the tube.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for surface-treating an inner peripheral surface of a fluororesin tube, and more specifically, a surface treatment of an inner peripheral surface of a fluororesin tube for modifying properties such as adhesion and wetness. Regarding the method.

[0002]

TECHNICAL BACKGROUND OF THE INVENTION Fluororesin, especially PTFE, PF
Since A is excellent in properties such as heat resistance, chemical resistance, and non-adhesiveness, it is used as a cover material for a heat fixing roller used in, for example, an electronic copying machine.

Conventionally, as a heat fixing roller for an electronic copying machine, a fixing roller in which an elastic layer is formed on the outer peripheral surface of a roll core and the outer peripheral surface of the elastic layer is covered with a fluororesin tube through an adhesive is known. Has been.

A fixing roller in which the outer peripheral surface of the roll core is directly covered with a fluororesin tube is also known. However, as mentioned above, fluororesin has excellent heat resistance, chemical resistance, and non-adhesiveness, but its surface energy is extremely small and it has poor wettability, so it is used to bond other materials with adhesives. It is extremely difficult to do.

Therefore, when coating the outer peripheral surface of the roll core of the fixing roller with a fluororesin tube as described above, the inner peripheral surface of the fluororesin tube is first surface-treated to give adhesiveness, and thereafter, A method of adhering the roll core and the fluororesin tube via an adhesive is adopted.

As a method of surface-treating a fluororesin,
The following methods (1) and (2) are known. (1) Sodium / liquid ammonia solution method: A method in which the surface of a fluororesin is brought into contact with a solution prepared by dissolving an alkali metal such as sodium in a liquid ammonia solution.

(2) Tetra-etching method: a method in which the surface of a fluororesin is brought into contact with a solution of an electron-donating complex of an alkali metal (eg, sodium dispersion of naphthalene in which sodium is dispersed in naphthalene, which has a relatively high boiling point) ..

[0008] Among these methods, the "sodium-liquid ammonia solution method" has a better adhesion treatment (surface treatment) effect than the "tetra-etch method". By the way, in the tetra-etch method, an effect of a wetting index of about 40 dyne and in the sodium / liquid ammonia method is obtained with a wetting index of 54 dyne or more.

However, by adopting these methods,
For example, in the case of performing inner surface treatment of a fluororesin tube, conventionally, the surface treatment liquid is allowed to flow down into the tube whose outer surface has been masked in advance, or the tube whose outer surface has been masked in this way is surfaced. Although it is immersed in the treatment liquid, there is a problem that it is difficult to efficiently perform the inner peripheral surface treatment of the fluororesin tube.

In particular, in the "sodium / liquid ammonia solution method", the reaction rate with the fluororesin is fast, and since the surface treatment of the fluororesin by this method is carried out at room temperature, ammonia gas is generated by boiling the liquid. There is also a problem that processing unevenness occurs.

When the inner peripheral surface of the fluororesin tube is treated by the conventional "sodium / liquid ammonia solution method" as described above, gas is accumulated inside the tube, and as a result, the tube swells and is broken. It was difficult to impart good and uniform adhesiveness to the inner surface of the tube, such as wrinkles.

In particular, the fluororesin tube used as the cover of the fixing roller is usually 20 μm to 200 μm.
Because it is thin, the tube is likely to break or wrinkle.

[0013]

It is an object of the present invention to solve the above-mentioned problems, and it is possible to uniformly treat the inner peripheral surface without unevenness of treatment, exhibit excellent adhesiveness, and It is an object of the present invention to provide a surface treatment method for the inner peripheral surface of a fluororesin tube, in which the occurrence of breaks and wrinkles that lose smoothness is prevented.

In particular, it is an object of the present invention to provide a surface treatment method which is preferably applied to the above-mentioned sodium / liquid ammonia solution method.

[0015]

SUMMARY OF THE INVENTION In the method for treating the inner peripheral surface of a fluororesin tube according to the present invention, a surface treatment liquid is injected into the fluororesin tube provided with a closed portion from the open end of the tube and stored above the closed portion. Then, by moving the closed portion in the up-down direction (from one opening end to the other opening end), the contact portion between the inner surface of the fluororesin tube and the surface treatment liquid is moved to make the fluororesin. It is characterized by treating the inner peripheral surface of the tube.

In a preferred embodiment of the present invention,
The contact portion between the inner peripheral surface of the fluororesin tube and the surface treatment liquid is moved downward from the upper open end of the fluororesin tube arranged obliquely or vertically so as to move relative to the tube. Is moved downward (from the inner peripheral surface of the upper opening end side to the inner peripheral surface of the lower opening end side).

As described above, in order to move the closed portion relative to the tube from the upper open end of the fluororesin tube downward, for example, a closed member forming the closed portion (eg pinch roll). Is fixed and the tube is pulled up above the blocking member, or the tube is fixed and the blocking member is pulled down below the tube.

In a preferred embodiment of the present invention,
The fluororesin tube is clamped by a pair of pinch rolls or pinch boards to close the tube. Furthermore, a liquid ammonia solution of an alkali metal such as sodium can be preferably used as the surface treatment liquid.

According to the present invention, since the inner peripheral surface of the fluororesin tube is surface-treated by the above-described method, the inner peripheral surface of the fluororesin tube should be treated uniformly without unevenness in the treatment. It has excellent adhesiveness to other members, and prevents breakage and wrinkles that would cause the tube to lose its smoothness.

As described above, when the tube made of fluororesin is pinched by a pair of pinch rolls or pinch boards to close the tube, the movement of the closed portion (that is, movement of the stored treatment liquid) is promptly performed at a constant speed. Therefore, uneven processing is less likely to occur.

When a treatment liquid prepared by dissolving an alkali metal such as sodium in a liquid ammonia solution is used as the surface treatment liquid, the wetting index is large and an excellent surface treatment effect can be obtained.

[0022]

DETAILED DESCRIPTION OF THE INVENTION The method for treating the inner peripheral surface of a fluororesin tube according to the present invention will be specifically described below with reference to FIG.

In the present invention, a fluororesin tube is used. Examples of the fluororesin used when forming the tube include PTFE, PFA, FEP,
Examples thereof include ETFE, CTFE, PVDF, and PCTFE. Among them, PTFE and PFA are preferably used because of their heat resistance and non-adhesiveness.

The size of the tube formed of such a fluororesin is not particularly limited, but when it is used as a fixing roll cover, the outer diameter is usually about 1 to 10 cm and the wall thickness is 10. It is about 400 μm.

Further, the length of the tube is such that when the inner peripheral surface of the tube is treated with the sodium / liquid ammonia solution, the generated ammonia gas escapes to the upper open end side of the tube through the mandrel. It is not particularly limited as long as it is within the range that can be obtained, but preferably 100 to 5
It is about 000 mm.

In the present invention, for example, as shown in FIG.
A cylindrical mandrel (mandrel) 3 is attached to the upper open end 2a of the tube, and the upper open end 2a of the tube 1 is attached.
Hold the top of the tube with the holder 4 so that
The tubes are arranged diagonally or vertically, preferably vertically.

Next, in the present invention, a part of such a fluororesin tube is closed so that the surface treatment liquid contained therein does not flow. In order to close the fluororesin tube, for example, a pair of pinch rolls 10 may be used to sandwich (pressurize / clamp) the tubes so that the inner peripheral surfaces of the tubes are in close contact with each other.

The method of closing the tube is not limited to such a method, but when the tube is closed by using a pair of pinch rolls or a pinch board as described above, the movement of the closed portion is moved at a constant speed. It can be carried out promptly, and accordingly, uneven processing is less likely to occur.

When surface-treating the inner peripheral surface of the fluororesin tube arranged as described above, as shown in FIG. 1, from the inner peripheral surface upper part (upper opening end 2a side) to the inner peripheral surface lower part (lower opening end). 2b), the portion of the tube separated by an appropriate distance from the upper opening end is closed according to the amount of the surface treatment liquid 7, and the closed portion is located below (on the lower opening end side). ) Toward the vehicle) at a speed to be described later.

When the inner peripheral surface of the fluororesin tube arranged as described above is processed, the inner peripheral surface lower portion (lower opening end 2b side) to the inner peripheral surface upper portion (upper opening end 2a) are treated.
When the surface treatment is sequentially performed on the side), the lower open end of the tube may be closed and the closed portion may be sequentially moved toward the upper open end.

In the present invention, in particular, it is desirable that the former, that is, the inner peripheral surface of the tube is successively processed from the inner peripheral surface on the upper opening end side to the inner peripheral surface on the lower opening end side as described in detail below. When the surface treatment is performed by the method, a more uniform treatment can be performed while maintaining the tube shape in a good condition.

Next, in the present invention, for example, FIG.
A desired amount of the surface treatment liquid 7 is injected into the tube from the upper open end 2a of the above, and is stored in the upper portion 8 above the closed portion 5. As the surface treatment liquid, a solution used in the above-mentioned “sodium / liquid ammonia solution method”, that is, a liquid ammonia solution (1) of alkali metal such as sodium or a solution used in “tetra-etch method”, that is, an electron of alkali metal Examples thereof include a donor type complex (eg, a sodium dispersion of naphthalene in which sodium is dispersed in naphthalene) having a relatively high boiling point), and the former solution (1) is preferably used. When the solution (1) is used, the wetting index is large and an excellent inner surface treatment effect can be obtained.

The concentration of the sodium / liquid ammonia solution (1) varies depending on the flow-down velocity of the surface treatment liquid (movement velocity of the clogging part) and the amount of the surface treatment liquid used, and is not generally determined, but it is usually A solution in which 0.3 to 20.0 g of sodium is dissolved in 1 liter of liquid ammonia is used. It should be noted that the sodium concentration may be further increased in order to secure higher adhesiveness to the inner surface of the fluororesin tube that is brought into contact with another member.

Further, for example, in the case of the sodium / liquid ammonia solution having the above-mentioned concentration, from the surface of the treatment liquid to the blocking portion 5
The solution is used in an amount such that the depth up to about 2 to 30 cm.

In the present invention, the closing portion 5 is stored in the upper portion 8 of the closing portion 5 by gradually moving the closing portion 5 from the tube upper opening end 2a to the lower opening end 2b as described above. The contact portion 6 between the surface treatment liquid 7 and the inner peripheral surface of the fluororesin tube is sequentially moved from the inner peripheral surface side of the upper opening end of the tube to the inner peripheral surface side of the lower opening end, so that the inner surface of the tube Perform processing.

When the inner peripheral surface of the tube is treated by such a method, the inner peripheral surface of the tube is surface-treated with a uniform density. Therefore, when other members are abutted and adhered to the inner peripheral surface of the tube. Moreover, uneven adhesion is unlikely to occur, resulting in a uniform color with no uneven appearance.

In order to gradually move the blocking portion 5 from the tube upper opening end 2a to the lower opening end 2b in this manner, for example, the mandrel (mandrel) 3 and the holder 4 are fixed together with the upper opening end 2a. Then, the pinch roll of the closing member may be pulled down.

Alternatively, a pair of pinch roll positions for pressurizing and sandwiching the tube may be fixed, and the tube 1 may be pulled up above the pinch roll. The movement speed of the surface treatment liquid by such a method is as follows.
In the case of 0.1 to 100 m / min, preferably 2 to 50 m
/ Min. When the inner surface of the tube is treated at such a speed, the treatment boundary surface 9 becomes stable in the “solid (fluorine resin) -liquid (liquid (1))” state, and the treatment liquid boils along with the surface treatment. The gas generated thereby can quickly escape to the upper side of the tube, and uneven treatment is unlikely to occur.

In the present invention, the tube inner surface may be treated with the surface treatment solution as described above, and then the tube inner surface may be washed with water and dried.

[0040]

According to the present invention, in particular the conventional "processing effect"
Although it is superior to the above, it is preferably applied to the "sodium / liquid ammonia solution method", which is said to have problems such as uneven treatment when it is actually adopted as a treatment method. It is possible to obtain a uniform treatment effect, and it is possible to easily treat the inner peripheral surface of the thin fluororesin tube that is the object to be treated. Moreover, the smoothness of the outer surface of the tube is not lost by such inner surface treatment.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of an inner peripheral surface treatment method for a fluororesin tube according to the present invention.

[Explanation of symbols]

1 ... PFA tube, 2 ... open end, 2a ... upper open end,
2b ... Lower open end, 3 ... Mandrel, 4 ... Holder, 5
... Closure part, 6 ... Contact part between the surface treatment liquid and the inner peripheral surface of the fluororesin tube, 7 ... Surface treatment liquid, 8 ... Upper part of the closure part (treatment liquid reservoir), 9 ... Boundary surface, 10 ... Pinch roll ..

Claims (5)

[Claims] 1. A fluororesin tube provided with a closed portion is filled with a surface treatment liquid from the open end of the tube to be stored above the closed portion, and the closed portion is moved in the vertical direction to obtain a fluororesin. A method for treating an inner peripheral surface of a fluororesin tube, which comprises treating the inner peripheral surface of the fluororesin tube by moving a contact portion between the inner peripheral surface of the fluorotube and the surface treatment liquid. 2. The fluorine according to claim 1, wherein the contact portion between the inner peripheral surface of the fluororesin tube and the surface treatment liquid is moved downward by moving the closed portion downward. Inner surface treatment method for resin tubes. 3. The method for treating the inner peripheral surface of a fluororesin tube according to claim 1, wherein the tube is closed by sandwiching the fluororesin tube with a pair of pinch rolls or pinch boards. .. 4. A fluororesin tube provided with a closed portion is filled with a surface treatment liquid from the open end of the tube to be stored above the closed portion, and a closed member such as a pinch roll constituting the closed portion is fixed. In this state, by moving the fluororesin tube upward, the contact portion between the fluororesin tube inner peripheral surface and the surface treatment liquid is moved to treat the inner peripheral surface of the fluororesin tube. The inner peripheral surface treatment method for a fluororesin tube according to any one of claims 1 to 3. 5. The fluororesin tube according to claim 1, wherein the surface treatment liquid is a treatment liquid obtained by dissolving an alkali metal such as sodium in a liquid ammonia solution. Inner surface treatment method.