JPH01221240A - Polyvinyl alcohol film and its manufacture - Google Patents

Abstract

PURPOSE:To maintain water resistance and dimensional stability extending over a long period of time, by applying a fluorine or silane thin film coating of a specific thickness to the surface of a polyvinyl alcohol film through plasma polymerization. CONSTITUTION:A fluorine or silane thin film of 500-10000Angstrom thick is formed on the surface of a polyvinyl alcohol film through a plasma polymerization method by making use of a fluorine compound or an organic silicon compound as a monomer. The plasma polymerization method designates a low-temperature plasmic polymerization method where plasma is generated singly or under mixing with nonpolymerizable gas by making use of polymerizable gas such as the fluorine compound or the organic silicon compound and the thin film is formed on the surface to be treated. With this construction, the polyvinyl alcohol film whose retention of strength after underwater immersion for 24 hours is 70% or higher is obtained.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is directed to applying a thin film coating to the surface of a polyvinyl alcohol (hereinafter abbreviated as PVA) film by plasma polymerization, which solves the disadvantages of PVA film.
Regarding technology for increasing and improving water resistance, especially underwater 2
PVA with a strength retention rate of over 70% after 4 hours of immersion
This invention relates to a film and its manufacturing method.

[Conventional technology]

PVA film is sensitive to water, and when it comes into contact with water, the film stretches, ie, the dimensions of the film change, and the strength of the film decreases significantly. In order to solve these drawbacks, coating the film surface with urethane with a thickness of 5μ or more reduces the permeation rate or diffusion rate of water until it reaches the film surface, improving the strength and dimensional stability of the film. Processing methods are being used to hold the material for a long time.

However, in this processing method, an aqueous emulsion cannot be used in the urethane coating process, and an organic solvent must be used, so it cannot be said to be a preferable processing method from an industrial standpoint in terms of environmental hygiene and drainage. Furthermore, the effect was not achieved unless the urethane film was made thicker.

[Problem to be solved by the invention]

The present invention solves these process problems and
The present invention relates to a PVA film whose purpose is to maintain water resistance and dimensional stability of the film over a long period of time, and a method for producing the same.

[Means to solve the problem]

That is, the present invention provides a polyvinyl alcohol film having a fluorine-based or silane-based thin film having a thickness of 500 to 10,000 on at least one surface of the vinyl alcohol film.

2) The polyvinyl alcohol film according to claim 1, which has a strength retention rate of 70% or more after being immersed in water for 24 hours.

3) A polyvinyl alcohol film characterized by using a fluorine compound or an organosilicon compound as a monomer and forming a fluorine-based or silane-based thin film with a thickness of 500 to 10,000 on the surface of the polyvinyl alcohol film by plasma polymerization. manufacturing method.
”.

The PVA film of the present invention may be made of vinyl alcohol obtained by a dry method or a copolymer of vinyl acetate (saponification degree of 20 to 100 molar, polymerization degree of 100 to 10
000) in water at 40% (wt%) and form a bottom-shaped film.The film may contain 10 to 15% (wt%) of glycerin as a plasticizer. There is no problem even if the film is mixed.Furthermore, the film used may be a uniaxially stretched film, a biaxially stretched film, or an unstretched film.

The plasma polymerization method used in the present invention refers to a low-temperature plasma polymerization method, in which plasma is generated using a polymerizable gas such as a fluorine compound or an organosilicon compound alone or in a mixture with a non-polymerizable gas, and is applied to the surface to be treated. This is a method of forming a thin film.

The plasma device used in the present invention may be either a Pelger type device or a drum type device. The former is 1
3.561'l? A high frequency power source of iHz is employed, and the electrodes are preferably symmetrical disc electrodes, but are not limited to this, and any material that can generate low-temperature plasma may be used.

Also, from the viewpoint of uniformity of processing, the image electrodes must be held parallel.

Furthermore, it is preferable to arrange the electrodes perpendicularly to the direction in which the plasma travels in order to form a uniform thin film on the surface of the object to be processed. The latter is also 13, 56 MHz
A high frequency power source is employed, but the present invention is not necessarily limited to this. The electrodes are preferably asymmetrically rigged electrodes. The shape of the electrode on the side that does not come in contact with the object to be processed can be arbitrarily selected from one or more cylinders or rods with a polygonal cross section with an acute angle, but the processing effect also depends on the number of electrodes. On the other hand, if it is too small, the treatment effect will be small. The shape is preferably cylindrical. In addition, the shape of the electrode on the side that may come into contact with the object to be processed is preferably drum-shaped.Also, metals such as stainless steel, copper, iron, and aluminum can be used as the material of the electrode. It may also be coated with glass, ceramic, etc. In the case of a large-scale plasma processing apparatus in which a large amount of cloth is being processed and therefore a large electrode is required, an asymmetric electrode is preferable from the viewpoint of uniformity of processing.

In the present invention, the monomer introduced into the true nitrogen system is either a polymerizable gas alone or a mixture of a polymerizable gas and a non-polymerizable gas, which is already gaseous or liquid at room temperature. good.

A fluorine compound or an organosilicon compound is used as the polymerizable ganu, and examples of the former include C2F4 (tetrafluoroethylene), C3F6 (hexafluoropropylene), and C3F8.
(propane hefluoride), C4F3 (butene hefluoride)
, 03F60 (hexafluoropropylene oxide, C2H
4F2 is a type of fluorinated ethane), and the latter is CHa Si (OCH3)3 (methyltrimethoxysilane), (CH3)25i(OCH3)2 (dimethyldimethoxysilane), (CHa)3St α?H
3) (trimethylmethoxysilane), St (OCH3
)4(tetramethoxysilane), (CH3)(H)Sl
(OCH3)2(methyldimethoxysilane), C
H2-CH8i (OCHQ3 (hinyltrimethoxysilane), CH2-CH8i (QC2H5)3 (vinyltriethoxysilane), (CH2-CH) (CH3)2S
i(OCRs) (cymethylhinylmethoxysilane), (
Alkoxysilane compounds such as CH2=CH)(CHa)Si(OCRs)z(methylvinyldimethoxysilane), CHaSiα3(methyltric, etc.).

silane), (CHs)2Siα2 (dimethyldichlorosilane), (CHa)a81α (trimethylchlorosilane), (CH3)asi
M-1 (CH3)3 (hexamethyldisilazane), (C
H3) One of the silazane compounds such as 2N5I(CH3)3 (dimethyltrimethylsilylamine) is used.

As a non-polymerizable gas as a carrier gas.

Inorganic gases such as Ar and Oz are used.

In a mixed system of a non-polymerizable gas and a polymerizable gas, the combination and ratio can be arbitrarily selected depending on the reactivity of the 7-mer gas, the performance of the formed thin film, etc.

In addition, in a mixed system of non-polymerizable gas and polymerizable gas, it is possible to introduce them separately into the vacuum system and mix them within the system, or to mix them in advance and introduce them at the same time. A polymerizable gas may be introduced during the discharge.

The degree of vacuum for generating low-temperature plasma is usually 0.0.
According to the study results of the present inventors, 0.01 to 50 Torr is used. □ Torr is preferable. The degree of vacuum is 0. When the OI Torr is lower than that, the mean free path of ions and electrons increases, and the energy of accelerated particles increases, but the total number of accelerated particles that reach the object to be processed is small, and the processing efficiency becomes somewhat low.

Moreover, while introducing gas into the processing chamber, the OIT
In order to maintain the temperature below orr, a vacuum pump with a very large displacement is required, which is not desirable considering the equipment cost. When the degree of vacuum is 5 Torr or more, the mean free path of ions, electrons, etc. becomes small, the energy of accelerated particles becomes small, and the processing efficiency becomes low even though the total number of accelerated particles is large. The plasma output acting on the discharge portion is preferably 0.1 to 5.0 watts/d.

As for the area of the discharge part, when the value of the output of the plasma discharge part is divided by the area of the object to be treated existing in the discharge part or the surface area of the counter electrode, whichever value is O, 1 to 5.0 watts/ It should be d. Plasma output is O, 1 watt/
- In the following cases, the plasma polymerization process takes time and the thickness of the polymerized film is not sufficient. When the plasma output exceeds 5.0 watts/cd, the discharge becomes unstable and etching is likely to occur in addition to polymerization. The processing time is preferably about 5 to 600 seconds. If it is less than 5 seconds, the thickness of the polymerized film will be low;
If the time is longer than 0.00 seconds, the thickness of the polymerized film is sufficient, but the plasma polymerized film may become colored, have a slightly hard surface, or become brittle, which may cause the plasma polymerized film to differ from its original function.

The thickness of the thin film formed by the plasma polymerization method was measured using a multiple interference microscope or an electron microscope. If a thin film produced by plasma polymerization using a fluorine compound or an organosilicon compound has a thickness of 500 to 10,000, the thin film has water repellency, stain resistance, chemical resistance, abrasion resistance, and antifogging properties. ,Heat-resistant.

It is extremely effective for water resistance, moisture absorption resistance, blocking resistance, etc., and unlike polymers produced by conventional polymerization, the thin film produced by plasma polymerization has a crosslinked structure. It is thought that it has the following characteristics.

When a fluorine or organosilicon film is coated on the surface of a PVA film using plasma polymerization, the water repellency and water resistance are significantly improved compared to an uncoated PVA film. The term "at least one surface" as used in the present invention means that either double-sided treatment or single-sided treatment can be selected depending on the purpose for which the film is used.

In the present invention, a strength retention rate of 70% or more means to first measure the strength in the vertical and horizontal directions in a dry state, calculate the average value, and then submerge the film in water (if only one side is treated, (so that only the treated surface is in contact with water), and
After leaving it for a while, take it out of the water, immediately measure the gi degrees in the vertical and horizontal directions, calculate the average value, divide that value by the dry average value, and multiply the value by lOO to get 70. This means the above. Please note the details below according to the examples! do.

Example 1 Behavior of water at a given time in an unstretched PVA film coated with a thin film by plasma polymerization using trimethylmethoxysilane, which is an organic silane compound, as a monomer and an unstretched PV A film not subjected to plasma treatment. Table 1 shows the tensile strength changes.

Table 1 Behavior and tensile strength of unstretched PVA film in water pVA film: Polymerized f-150C PVA dry film, unstretched film (plasma treatment conditions) Q plasma device: Pelger type, parallel plate electrode high frequency power source 13.56 MHz O monomer: Trimethylmethoxysilane 0 output electric crab 2
．． 3 watts/ctl Q processing time: 180 seconds Q film thickness: 2400 people Double-sided treatment <Tensile test measurement conditions> 0 Tensile tester: Instron TM-MO Tensile speed: 20σ/m1n O sample: 10z x 2.5 cm (length x width) The plasma treated film has a strength retention rate of 87 after 24 hours.
%, -1 The water resistance of the untreated film was 27%, which was significantly improved by the plasma treatment.

Example 2 Behavior of water at a given time in a biaxially stretched PVA film coated with a thin film using a plasma polymerization method using C2F4, which is one of the fluorine-based compounds, and a biaxially stretched PVA film that was not subjected to plasma treatment. Table 2 shows the change in tensile strength.

Table 2 Behavior and tensile strength of biaxially stretched PVA film in water PVA film: Dry film of PVA with degree of polymerization 2200, biaxially stretched film <Plasma treatment conditions> 0 Plasma device: Drum type, asymmetric electrode high frequency power source 1
3.56 MHz, non-grounded 0 monomer: C2F4 O output power crab 0.5 watt/- 〇 Processing time: 180 seconds 0 film thickness: 1600 people 0 single side processing <Tensile test measurement conditions> Same as Example 1.

As shown in the examples, the PVA film coated with a plasma polymerized thin film has a remarkable effect when compared to a non-plasma treated film, and even when immersed in water for a long time, the dimensional change of the film is suppressed to 1-3% elongation. Furthermore, the tensile strength of the film when immersed in water has a higher strength retention rate than the tensile strength of a film that is not immersed in water. These results revealed that the PVA film coated with the plasma polymerized thin film is practical in terms of water resistance and dimensional stability.

Patent applicant RiRashi Co., Ltd.

Claims (1)

[Scope of Claims] 1) A polyvinyl alcohol film having a fluorine-based or silane-based thin film having a thickness of 500 to 10,000 Å on at least one surface of the polyvinyl alcohol film. 2) A method for producing a polyvinyl alcohol film, which comprises forming a fluorine-based or silane-based thin film with a thickness of 500 to 10,000 Å on the surface of the polyvinyl alcohol film by plasma polymerization using a fluorine compound or an organosilicon compound as a monomer. .