JPH07102090A - Modifying method for surface of fluororesin tube - Google Patents

Abstract

PURPOSE:To modify (impart adhesive properties to) the surface of a fluororesin tube by treating the surface with plasma generated under specified conditions using nitrogen or air as the treating gas. CONSTITUTION:The outer surface of a fluororesin tube (esp. a tube made from an ethylene-tetrafluoroethylene copolymer) is modified by treating it for 15-60sec with a plasma generated under an oscillation frequency of 13.56MHz, a treating gas pressure of 0.02-1.5Torr, and a high-frequency output of 25-200W using nitrogen or air as the treating gas. For example, the surface of a fluororesin tube 2 is modified by placing a tube set jig 3 with the tube 2 held therein in a reactor 1 shown by the figure, reducing the pressure inside the reactor 1 to 0.05Torr or lower, leading air, the treating gas, through an inlet 4 into the reactor 1 to adjust the inside pressure to 0.4Torr, setting a high-frequency power source 8 (equipped with a ring electrode 6 and a matching box 7) to an oscillation frequency of 13.56MHz and an output of 100W to generate plasma, and thus treating the tube 2 for 30sec.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying the surface of a fluororesin tube, and more particularly to a method for modifying the surface of an ethylene-tetrafluoroethylene copolymer (ETFE) tube.

[0002]

2. Description of the Related Art As is well known, fluororesins have excellent properties such as non-adhesiveness, heat resistance, non-toxicity, weather resistance and chemical resistance. Among the fluororesins, ETFE is a type of fluororesin that combines the properties of the above-mentioned fluororesins with excellent processability. In particular, it can be processed by any method such as melt processing, extrusion molding, injection molding, and has excellent economic efficiency. It is something to demonstrate.

[0003] In addition, when a heterogeneous material, that is, a rubber or other resin is adhered to an ETFE tube to form a composite material, it is applied in the fields of electronics, chemistry, and machinery to impart functionality and improve physical properties. Is extremely significant for doing. Among them, E is used for the liquid fuel supply piping system.
A composite material of a TFE tube and a polymer has been studied and is extremely effective for its application. And
In order to impart adhesiveness, it is useful to perform surface modification such as improving the wettability of the tube surface. This surface modification technique relating to a fluororesin is roughly classified into a wet method and a dry method. The wet method is a method of impregnating a fluororesin into a solution in which sodium metal is dissolved in a solvent such as tetrahydrofuran together with naphthalene to chemically modify the surface. On the other hand, as the dry method, corona discharge treatment performed under atmospheric pressure, ion implantation performed under reduced pressure, plasma treatment, and the like can be considered.

The corona discharge treatment is a kind of gas discharge, and when the electric field between the conductors is not equal, a light-emission discharge that appears when a partial electric breakdown occurs at a large electric field on the surface before the spark discharge is used. It is a physical method of scraping the surface. In the ion implantation, the material to be treated is set in the vacuum container of the implanter, and the degree of vacuum is 10 ⁻⁵ to 10 ⁻⁶ Tor.
At r level, metal such as titanium is vaporized and ionized by a large local current in the arc spot to form neutral plasma, and then the titanium ions are accelerated to accelerate the beam and irradiate the material as a beam for modification. Further, in the plasma treatment, a material to be treated is set in a vacuum container and plasma is produced with argon gas or oxygen under a certain degree of vacuum, and various components in the plasma such as ions, electrons, radicals and This is a method of improving the surface structure of a material by using excited atoms or molecules to modify the material.

[0005]

However, the conventional technique has the following problems. 1. Wet method It was necessary to prepare a solution or suspension in advance, and a step such as washing was required after the treatment, and there was no time advantage in obtaining the final product. Further, the adhesiveness between the treated material and rubber or the like has varied considerably in strength. 2. Dry method Although the dry method is a relatively clean method, corona discharge,
Practically sufficient adhesive strength cannot be obtained by ion implantation and conventional plasma treatment. Especially in the case of plasma treatment, few attempts have been made for tubes as in the present invention.

The present invention has been made in view of the above circumstances, and is a surface of a fluororesin tube in a clean environment, having a relatively simple manufacturing process, and having a practically sufficiently high adhesive strength with rubber or the like. The purpose is to provide a reforming method.

[0007]

According to the present invention, one of nitrogen gas and air is used as a processing gas, and an oscillation frequency of 1 is used.
3.56MHz, processing gas pressure 0.02-1.5T
This is a method for modifying the surface of a fluororesin tube, characterized in that it is treated for 15 to 60 seconds with plasma generated under the condition of orr and high frequency output of 25 to 200W.

In the present invention, the reason why the gas for plasma generation is nitrogen gas or air is that its properties are extremely safe and inexpensive, and that the plasma generated contains sufficient chemical species for surface modification. This is because it can be generated.

In the present invention, the reason for setting the gas pressure of the processing gas to 0.02 to 1.5 Torr is that plasma itself is difficult to generate in regions other than the vacuum degree in this range, and even if plasma is generated, its concentration is low. This is because it is extremely thin and does not play a role of surface modification. In this invention,
A high-frequency output of 25 to 200 W and a treatment time of 15 to 60 seconds are not very effective as an effect of imparting adhesiveness at a higher output and a treatment time, but rather a high output and a plasma for a long time treatment. This is because the internal temperature rises and affects the dimensional stability of the ETFE tube. Because of the relatively low output and the relatively short treatment time, it is possible to develop the ETFE tube into a continuous surface treatment.

FIG. 1 shows a plasma processing apparatus according to the present invention. Reference numeral 1 in the figure is, for example, a reactor made of Pyrex glass having an inner diameter of 90 mm. In this reactor 1, ETF
A tube setting jig 3 on which the E tube 2 is placed is arranged. Further, the reactor 1 is connected with a pipe 4 for introducing a plasma gas and an exhaust pipe 5 leading to a rotary pump (not shown) for vacuuming the inside of the reactor 1. A ring electrode 6 for generating plasma is closely attached to the outer peripheral portion of the reactor 1, and is connected so as to receive signals from a matching box 7 for adjusting the output and a high frequency power source 8. ing.
A vacuum gauge (not shown) is arranged in the reactor 1.

[0011]

According to the present invention, the surface of the ETFE tube can be modified (adhesion can be imparted) in a clean environment with a relatively simple manufacturing process and in a short time.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, the tube set jig 3 with ETFE is placed in the reactor, and the inside of the reactor 1 is set to 0.05 Torr.
Reduce the pressure below r. Subsequently, the air for plasma is introduced to adjust the internal pressure of the reactor to 0.4 Torr. Then, the high frequency power source 8 sets the oscillation frequency to 13.56 MHz and the output to 100 W, and plasma is generated in this state, but this is held for 30 seconds.

As a result, the preset ETFE
Plasma acts on the outer peripheral surface of the tube physically and chemically, and the outer peripheral surface of the tube is surface-modified. Then, as evidence of the surface modification, the FT-IR, the wettability index, the contact angle, and the peel strength of the hot-pressed product with urethane rubber were measured. Figure 2 shows FT-I of untreated ETFE tube
FIG. 3 shows the spectrum of R and FIG. 3 shows the spectrum of the ETFE tube according to this example. Here, FIG. 3 is a difference spectrum used as a method of significantly expressing the difference between the spectrum of the processed product of the present invention and the spectrum of the unprocessed product (FIG. 2).

Comparing FIG. 2 with FIG.
Near 0 cm ^-1 (derived from -CH group), 1600 cm ^{-1 to} 1800
Around cm ^-1 (derived from -C = C- group or carbonyl group) and around 3500 cm ^-1 (derived from -NH group or -OH group)
The peak of is increasing. Therefore, it is presumed that these polar groups have a structure existing by the plasma treatment. In addition, the measurement result of the wetness index by the wetness index standard solution,
The results of the contact angle measurement with water and the peel strength value of the hot pressed product with urethane rubber are shown in "Table 1" below.

[0015]

[Table 1] However, in Table 1, the coating index of (1) indicates the value measured by the coating standard solution. The contact angle in (2) is the contact angle with water and is the value measured by a goniometer. The peel strength of (3) was obtained by cutting the treated ETFE tube into a film and hot pressing it with urethane rubber having a thickness of 1 mm at 200 ° C. for 1 minute under the condition of 1 kg / cm ² and then cutting it to a width of 10 mm to obtain ETFE. A 180 ° peeling test between urethane rubbers was carried out using a universal testing machine to determine the peel strength.

[0016]

As described in detail above, according to the present invention, in a clean environment, the manufacturing process is relatively simple, and the adhesive strength with urethane rubber is sufficiently high in practical use.
It is possible to provide a surface modification method for a fluororesin tube such as ETFE, which can be easily developed into a method for continuously modifying the surface of an FE tube.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a plasma processing apparatus according to the present invention.

FIG. 2 FT-IR chart of untreated ETFE tube.

FIG. 3 is an FT-IR chart of ETFE tubes treated according to an example of the present invention.

[Explanation of symbols]

1 ... Reactor, 2 ... ETFE tube, 3 ... Tube setting jig, 4 ... Piping, 5 ... Exhaust pipe,
6 ... Ring electrode, 7 ... Matching box, 8 ... High frequency power supply.

Claims (1)

[Claims] 1. An oscillation frequency of 13.56 MHz, a gas pressure of the processing gas of 0.02 to 1.5 Torr, and a high frequency output of 25 to 2 using either one of nitrogen gas and air as the processing gas.
A surface modification method for a fluororesin tube, characterized in that the surface of the fluororesin tube is treated with plasma generated under a condition of 00 W for 15 to 60 seconds.