JP2611384B2 - Polyphenylene sulfide film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyphenylene sulfide film, and more particularly, to a protective film, a packaging film, a label, which has a strong self-heat-fusing property having water resistance.
The present invention relates to a polyphenylene sulfide film that can be effectively used for capacitors and the like.

[Prior Art] It is well known that a polyphenylene sulfide film cannot be thermally bonded to another film of the same kind or to a different kind of film because it has no heat-fusing property until then.

Conventionally, it has been proposed to carry out a corona discharge effect or a plasma treatment in order to improve the heat sealability of such a polyphenylene sulfide film (JP-A-57-187327).

[Problems to be Solved by the Invention] However, as a result of further study by the present inventors, it has been found that the above-described corona discharge treatment has the following problems.

That is, the polyphenylene sulfide film subjected to the corona discharge treatment has a self-fusing property, but is easily peeled off by supplying water. That is, there is a problem that there is no water resistance.

In addition, in the case of the method based on the plasma treatment specifically disclosed in the above-mentioned Japanese Patent Laid-Open, ie, when the polyphenylene sulfide film is subjected to the plasma treatment in a gas atmosphere, the processing conditions (atmosphere gas, input power, processing speed, processing apparatus, etc.) In some cases, it was found that there was no self-heat-fusion property, or there was self-heat-fusion property but no water resistance.

The present inventors have conducted intensive studies on measures to improve the problems of the prior art, and as a result, when the surface of the polyphenylene sulfide film is modified to have a specific chemical structure, sufficient self-heat-fusing property is obtained. The present inventors have found that they have excellent water resistance as well as having the same, and have arrived at the present invention.

Therefore, an object of the present invention is to provide a polyphenylene sulfide film having water resistance and strong self-heat-fusing property.

[Means for Solving the Problems] An object of the present invention is to provide a method in which the ratio of carbon atoms bonded to oxygen atoms to all carbon atoms on the surface is 3% to 20%.
%, And the ratio of sulfur atoms bonded to oxygen atoms in the state of sulfonic acid, sulfonate ion or sulfonate to all sulfur atoms is 0.3% or more and 3% or more.
%, Which is achieved by a polyphenylene sulfide film characterized by being in the range of less than 10%.

The polyphenylene sulfide film used in the present invention includes the following repeating unit Refers to a film made of a resin composition mainly composed of poly-p-phenylene sulfide.
The content of poly-p-phenylene sulfide is at least 80% by weight, preferably at least 90% by weight in view of the heat resistance and various mechanical properties of the film, and the above-mentioned structural unit in poly-p-phenylene sulfide Is preferably 90 mol% or more.

The resin composition may contain an inorganic or organic filler, a lubricant, a UV absorber, a colorant, and the like, for the purpose of improving abrasion resistance and weather resistance within a range that does not impair the properties of the polyphenylene sulfide film. .

Polyphenylene sulfide film thickness is 0.4μm ~ 1
The thickness is preferably in the range of 00 μm, and the average surface roughness Ra of the film is preferably in the range of 0.03 to 0.10 μm, but is not limited to these ranges.

The polyphenylene sulfide film used in the present invention can be produced by a well-known method described in, for example, JP-A-55-111235.

In the polyphenylene sulfide film of the present invention, first, it is important that the ratio of carbon atoms bonded to oxygen atoms to the total carbon atoms on the surface is in the range of 3% to 20%. The ratio of sulfur atoms bonded to oxygen atoms in the state of sulfonic acid, sulfonate ion or sulfonate is 0.3% or more 3
It is important to be in the range of less than%.

Here, the chemical bonding state of carbon and sulfur on the surface of the polyphenylene sulfide film can be known by, for example, X-ray photoelectron spectroscopy (XPS) measurement. In other words, the film surface is irradiated with X-rays by XPS measurement, the 1S peak of carbon and the 2P peak of sulfur of the emitted X-ray photoelectrons are taken out, and peak splitting is performed to determine what kind of chemical bond between carbon and sulfur. It is possible to know the ratio of the combination.

In the present invention, the carbon atom bonded to the oxygen atom is
When the C _1s peak obtained by XPS measurement was decomposed, -COO-, = C
= O, = C-O- refers to the carbon atom belonging to the bonding state.

On the surface of the polyphenylene sulfide film,
When the ratio of carbon atoms bonded to oxygen atoms to all carbon atoms is less than 3%, sufficient self-heat-fusibility cannot be obtained. It is not preferable because it cannot be obtained and the surface of the film becomes hard and brittle, causing a decrease in abrasion resistance and the like. More preferably, it is in the range of 4% to 15%.

In the present invention, a sulfonic acid, a sulfonate ion or a sulfur atom bonded to an oxygen atom in a sulfonate state irradiates the film surface with X-rays by XPS measurement, and the S _2p peak of the emitted X-ray photoelectrons is measured. when the peak splitting removed, ▲ SO ^2- ₄ ▼ or ▲ SO ^- ₄ ▼ refers to a sulfur atom which is attributable to bonding state.

At the surface, sulfonic acid for all sulfur atoms,
If the proportion of sulfur atoms bonded to oxygen atoms in the state of sulfonate ions or sulfonates is less than 0.3%, there is a disadvantage that self-heat-fusion properties may be reduced or may not be obtained. . If the above ratio is 3% or more, water resistance after self-heat fusion cannot be obtained. A more preferable range of the ratio of the sulfur atom bonded to the oxygen atom in the state of sulfonic acid, sulfonate ion or sulfonate relative to all the sulfur atoms is 0.5% to 2%.

One of the methods for producing such a polyphenylene sulfide film
Examples can be obtained by subjecting the surface or both surfaces of a polyphenylene sulfide film as a raw material to low-temperature plasma treatment, for example, in a selected mixed gas atmosphere and plasma conditions.

The figure illustrates an example of a low-temperature plasma processing apparatus that can be used in the present invention.
Is sent out to the discharge processing section 9 by the feed roll 2. A gas having a predetermined composition is supplied to the discharge processing unit 9 from the gas introduction system 8, and is maintained at a predetermined gas pressure by a simple exhaust device (not shown). The film 1 is processed in a discharge processing unit by a discharge formed between the high voltage application electrode 3 and the grounded drum-shaped electrode 4 by a high frequency high voltage applied from a high voltage power supply 5 via a matching transformer 6. Then, it is taken up by a take-up roll 7.

The discharge is provided by opposing a high-voltage application electrode in which the surface of a conductor such as a metal tube, which is cooled by flowing a coolant such as water therein, is covered with a dielectric such as rubber or glass, and the electrode. Is formed between the electrode and the electrode for supporting the object to be processed, the surface of which is to be formed is coated with a similar dielectric. The thickness of the dielectric is preferably in the range of 0.1 to 5 mm.

It is not necessary that the number of high-voltage application electrodes and the number of electrodes supporting the object to be processed be equal, and for one electrode supporting the object to be processed,
It is preferable to provide two or more high voltage application electrodes.

The frequency of the high voltage applied to the high voltage application electrode is preferably selected in the range of 50 KHz to 500 KHz.

In the present invention, as a gas suitably used for the plasma treatment, a mixed gas composed of an inert gas such as helium, neon, argon, and krypton and a small amount of air is exemplified. The total amount of air components (oxygen, nitrogen, water vapor, etc.) contained in the processing gas is preferably in the range of 0.15 ppm to 500 ppm in total. If the constituent gas of air such as oxygen, nitrogen, water vapor, etc. is less than 0.15 ppm, the self-heat fusion property is not sufficient, and if the total amount of these gases exceeds 500 ppm, water-resistant self-heat fusion is performed. Sex is not obtained.

The pressure of the atmosphere is preferably selected in the range of 0.1 to 1000 Torr, more preferably in the range of 10 to 900 Torr.

As for the processing intensity, the processing is preferably performed at a processing power density of 50 W · min / m ² or more, and more preferably at a processing power density of 100 W · min / m ² or more. Here, the processing power density means the output is the width of the discharge part (the axial direction of the drum electrode)
Divided by the processing speed of the film.

The polyphenylene sulfide film obtained by the present invention exhibits strong self-heat-fusion properties and has excellent water resistance, so that it can be effectively used for applications such as protective films, packaging films, labels, and capacitors.

[Effects of the Invention] The polyphenylene sulfide film of the present invention has a high degree of self-heat fusing property because the surface has a specific chemical structure, and has a remarkable practical effect of being excellent in water resistance. It is.

Although it is not clear why such an effect is obtained, polar groups such as a carbon atom and a sulfur atom bonded to an oxygen atom, for example,> C = O, -COH, -COOH, and a sulfonic acid group are self-heat-fusible. Is considered to be an effective source for expressing On the other hand, it is presumed that by setting the presence of the sulfonic acid group within a certain range, it was possible to impart self-heat-fusibility excellent in water resistance.

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. The following methods were used for measuring the characteristics of the present invention in the examples.

(1) Method for measuring the chemical structure of the surface of a polyphenylene sulfide film X-ray photoelectron spectrometer (ESCA750 manufactured by Shimadzu Corporation)
The 1S peak of carbon and the 2p peak of sulfur are measured using. Since this peak is a combination of the peaks in the chemical bond state as shown below, it is decomposed into signals from the chemical bond state by Gaussian distribution approximation, and the peak height of each signal after decomposition is converted to each chemical bond state. Calculate the ratio of the number of atoms. The sum of the ratios of the numbers of the atoms in the following chemical bonding states is defined as the total number of carbon atoms or the total number of sulfur atoms.

The C _1s peak is π-π ^* , -COO-, = C = O, = C-
It is attributed to O-, neutral carbon, and -CS-.

S _2p peak ^{π-π *, ▲ SO 2-} 4 ▼, ▲ SO - 3 ▼, -C-
SO ₂ -C-, -C-SO ₃ -C-, -C-SO-C-, -C-
S-C-.

Here _{^{▲ SO 2- 4 ▼, ▲ SO}} - 3 ▼ indicates Surufuon acid, sulfonic acid ion or sulfonic acid salt.

(2) Method of Measuring Adhesive Strength The treated surfaces are superimposed on each other, and two polyphenylene sulfide films are passed through a roll heated at 220 ° C. once to be thermally fused. The distance between the rolls was 3 kg / cm ² , and the roll rotation speed was 1 m / min.

Next, the heat-fused polyphenylene sulfide film was set on a shopper type tensile tester (manufactured by Daiei Kagaku Seiki Seisaku-Sho, Ltd.) and peeled in the 180 ° direction. The peeling speed was 20 cm / min.

In the above method, the peeling was performed while continuously supplying water, and the measured adhesive strength was defined as wet adhesive strength.

(3) Measurement of air component content Mass filter mass spectrometer (MSQ-1 manufactured by Nippon Vacuum Technology)
Using 50A), gas spectra in the processing apparatus after evacuation and after introduction of the processing gas were measured. The total amount of H ₂ O, N ₂ and O ₂ determined from this spectrum was defined as the amount of the air component.

Example 1 A plasma processing apparatus shown in FIG.
Of polyphenylene sulfide film (“Torelina” manufactured by Toray Industries, Inc.) was processed.

1 mm thick glass was used as a derivative to be coated on the electrode, and the distance between the high voltage application electrode and the drum electrode 4 was set to 1 mm.

The inside of the discharge processing section 9 is evacuated to a range of 1 × 10 ⁻³ Torr to 4 × 10 ⁻³ Torr, and argon gas is introduced from a gas introduction system.
Keep at 600 Torr. At this time, the amount of air component in the process gas is 2
It was in the range of 8 ppm to 8 ppm.

Next, 110 KHz is applied between the high voltage application electrode 3 and the drum electrode 4.
Is supplied from the high-voltage power supply 5 to generate plasma. The input power was 1KW at the power output.

The processing was performed by passing the substrate through the generated plasma at a speed of 7 m / min (processing power density: 240 W · min / m ² ).

The chemical structure, dry adhesive strength and wet adhesive strength of the surface of the obtained polyphenylene sulfide film were measured, and the results are shown in Table 1.

As is clear from Table 1, when having the surface structure specified in the present invention, it has an extremely high dry adhesive strength,
It can be seen that the wet adhesive strength is also higher than the dry adhesive strength.

Comparative Examples 1, 2, and 3 In the same manner as in Example 1 except that the exhaust gas in the discharge processing section 9 was set to 1 × 10 ⁻⁴ or less and the introduced gas was set to 97.5: 2: 0.5 of argon: nitrogen: oxygen. The surface-treated one is referred to as Comparative Example 1.

Further, a case where the processing was performed in the same manner as in Comparative Example 1 except that the exhaust gas in the discharge processing unit was set to 2 × 10 ⁻³ is referred to as Comparative Example 2. Further, Comparative Example 3 was subjected to surface treatment in the same manner as in Comparative Example 1 except that the gas to be introduced was a mixed gas of argon: nitrogen: oxygen of 70: 24: 6.

Table 1 shows the measurement results of the chemical structure and properties of the surface of the obtained polyphenylene sulfide film.

As is evident from Table 1, in each of Comparative Examples 1 and 2, although the dry adhesive strength was sufficiently large, the wet adhesive strength was almost nonexistent. In the case of Comparative Example 3, the dry adhesive strength was also reduced, and a sufficient adhesive strength could not be obtained, so that it was not practical.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a plasma processing apparatus that can be used in the present invention. 2: Feeding roll 3: High voltage application electrode 4: Drum electrode 4: High voltage power supply

Claims (1)

(57) [Claims] (1) a ratio of sulfonic acid, sulfonic acid ion or sulfonic acid salt to all sulfur atoms on the surface, wherein a ratio of carbon atoms bonded to oxygen atoms to total carbon atoms is in a range of 3% to 20%; Wherein the proportion of sulfur atoms bonded to oxygen atoms is in the range of 0.3% or more and less than 3%.