JPH10273546A - Surface treatment method and ethylene-tetrafluoroethylene copolymer molded article - Google Patents

Abstract

(57) Abstract: A novel surface treatment method capable of obtaining a surface-treated product of an ETFE molded article having excellent boiling water resistance and weather resistance of a surface-treated surface and applicable to a wide range of adhesives, and a surface treated by the surface treatment method. Provide a treated ETFE molded body. An ethylene-tetrafluoroethylene copolymer molded article is subjected to discharge treatment in a mixed gas comprising an inert gas, a polymerizable unsaturated compound gas and a carbon oxide gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for a molded article of an ethylene-tetrafluoroethylene copolymer and a molded article surface-treated by the method.

[0002]

2. Description of the Related Art Ethylene-tetrafluoroethylene copolymer (hereinafter abbreviated as ETFE) is a fluororesin excellent in non-adhesion, stain resistance, transparency, chemical resistance, weather resistance and heat resistance. By utilizing its excellent properties, a composite sheet obtained by laminating an ETFE film on a polyvinyl chloride sheet, a thermoplastic sheet represented by a polyethylene sheet, or a thermosetting polyester sheet via an adhesive is used for wallpaper, It is used as a surface material for kitchen doors.

A material obtained by laminating an ETFE film on a painted metal plate using an adhesive is used as a surface material of a gas cooker hood and a wall panel of a kitchen. Further, a tube in which an ETFE tube is coated with rubber, urethane resin, nylon resin, or the like via an adhesive is used as a fuel tube having excellent gasoline barrier properties and durability.

[0004] In obtaining a laminate in which a non-adhesive ETFE molded article is firmly adhered to a plastic sheet, a metal plate or the like, the surface treatment of the ETFE molded article greatly affects the adhesiveness and its durability. As a surface treatment technique for a fluororesin molded article, a technique using corona discharge in air is generally used (Japanese Patent Publication No. 60-16345, Japanese Patent Application Laid-Open No. 63-953).
3). A method of performing corona discharge treatment in the presence of an organic compound has also been proposed (JP-B-37-17485, JP-A-5-92530). Furthermore, a method of performing a plasma treatment in the presence of an organic compound (JP-A-4-74525) has also been proposed.

[0005]

However, the above-mentioned conventional surface treatment method is excellent in the initial adhesion of the adhesive or ink applied to the surface of the ETFE molded product to the surface of the ETFE molded product, but the surface treatment effect is high. There are problems with the durability of the. In Japanese Patent Publication No. 60-16345, a laminate is obtained on a fluororesin film subjected to corona discharge treatment in air, for example, using an adhesive mainly composed of a thermoplastic polyester resin. so,
Before the adhesion decreases due to the decrease in the cohesive force of the adhesive due to the hydrolysis of the polyester resin, the interface between the treated surface of the fluororesin film and the adhesive occurs.

An epoxy resin having excellent water resistance is used for the purpose of preventing a decrease in cohesive force due to hydrolysis of the adhesive or preventing water from penetrating into an interface between the adhesive and the treated surface of the ETFE molded product. In the method (JP-A-63-9533), although it has an initial effect, an interface peeling between the treated surface of the ETFE molded product and the primer layer occurs in about 10 hours in a boiling water test.

In any of the above cases, an oxygen-containing functional group such as a hydroxyl group, a carbonyl group or a carboxyl group is formed on the surface of the ETFE molded article by corona discharge in the air. Also, a weak boundary layer (hereinafter referred to as WB) newly generated by cutting a part of the main chain on the ETFE surface is cut.
L). It is considered that the oxygen functional group is also generated in the WBL portion. Therefore, the temperature of the boiling water test 95
At １００100 ° C., the molecular motion of WBL becomes active, and it is assumed that the oxygen-containing functional group easily detaches from the ETFE surface together with WBL and moves to the adhesive side.

[0008] Therefore, the reason why the durability of the surface treatment effect of the ETFE molded article is reduced is that WBL formed on the surface of the ETFE molded article has low adhesion to ETFE and WBL.
This is considered to be because the oxygen-containing functional group generated in the portion does not effectively act on the adhesive or the like.

Also, the method of corona discharge treatment in the presence of an organic compound (Japanese Patent Publication No. 37-17485) has a problem that the effect of the surface treatment itself deteriorates with time as described in the specification. Further, in Japanese Patent Application Laid-Open No. 5-92530, it is necessary that the functional group of the organic compound used in the discharge treatment and the functional group of the adhesive used for lamination with another substrate have the same or affinity. It is necessary to change the organic compound used in the treatment according to the adhesive used, and the treatment operation becomes complicated.

In the plasma processing method using acetone (JP-A-4-74525), acetone is liquid at normal temperature and normal pressure, and the composition of a mixed gas is easily changed by temperature, so that it is difficult to perform continuous processing. is there.

[0011]

The present invention suppresses the formation of WBL on the surface-treated surface of an ETFE molded article,
ETFs that efficiently generate only oxygen-containing functional groups such as carbonyl groups or carboxyl groups, have excellent boiling water resistance and weather resistance on the surface-treated surface, and are applicable to a wide range of adhesives
It is an object of the present invention to provide a novel surface treatment method having a feature that an E-molded article surface-treated product is obtained, and an ETFE molded article surface-treated by the surface treatment method.

That is, the present invention provides an ETFE molded product,
Provided is a surface treatment method characterized by performing discharge treatment in a mixed gas comprising an inert gas, a polymerizable unsaturated compound gas and a carbon oxide gas. Also provided is an ETFE molded product surface-treated by the surface treatment method.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS ETFE used in the present invention is as follows.
It is a copolymer of ethylene and tetrafluoroethylene, and includes a copolymer of another copolymerized monomer.
Other copolymerized monomers include other fluoroolefins,
Other olefins, vinyl monomers and the like can be mentioned.
Examples of other fluoroolefins include C2 to C3 fluoroolefins such as chlorotrifluoroethylene, hexafluoropropylene, vinylidene fluoride, and vinyl fluoride. Further, a fluorovinyl monomer such as (perfluoroalkyl) ethylene may be used. Examples of other olefins include propylene and isobutylene. Examples of the vinyl monomer include vinyl ether, allyl ether, vinyl carboxylate, allyl carboxylate, and olefin.

Examples of the vinyl ether include cycloalkyl vinyl ethers such as cyclohexyl vinyl ether,
Examples thereof include alkyl vinyl ethers such as nonyl vinyl ether, 2-ethylhexyl vinyl ether, hexyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, and t-butyl vinyl ether.

Examples of the allyl ether include alkyl allyl ethers such as ethyl allyl ether and hexyl allyl ether.

Examples of the vinyl carboxylate or allyl carboxylate include vinyl or allyl carboxylate such as acetic acid, butyric acid, pivalic acid, benzoic acid and propionic acid. Further, as the vinyl ester of a carboxylic acid having a branched alkyl group, commercially available Beova-9 and Beova-10 (all manufactured by Shell Chemical Co., Ltd., trade names) may be used.

The above-mentioned comonomer may be used alone or in combination of two or more. The proportion of polymerized units based on tetrafluoroethylene in ETFE is
20-70 mol% is preferable.

In the present invention, the ETFE molded body is subjected to a surface treatment. The ETFE molded body may be composed of only ETFE, and may be composed of ETFE and another fluororesin, for example, hexafluoropropylene-tetrafluoroethylene. -Based copolymer, perfluoro (alkyl vinyl ether) -tetrafluoroethylene-based copolymer, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride-based copolymer, mixture with chlorotrifluoroethylene-ethylene copolymer resin, etc. Alternatively, a mixture with a resin other than the fluororesin is also applicable.

Other fluororesins or resins other than fluororesins may be used alone or in combination of two or more. When other fluororesins or resins other than fluororesins are used in combination, the mixing ratio of ETFE is usually 5
0% by weight or more is preferred.

Further, a mixture of any one or more of additives and fillers such as a pigment, an ultraviolet absorber, carbon black, carbon fiber, silicon carbide, glass fiber, mica, or a crosslinking agent is also applicable. .

Further, the shape of the ETFE molded product is E
There is no particular limitation as long as it is a TFE molded product, but for example, a film, sheet, tube, pipe, or fiber can be used.

The present invention is characterized in that the discharge treatment is performed in a mixed gas of an inert gas, a polymerizable unsaturated compound gas and a carbon oxide gas. The role of the inert gas in the present invention is to stabilize the discharge, remove the ETFE degradation products present on the very surface of the ETFE molded product, and suppress the cutting of the polymer main chain to activate the ETFE molded product surface, The reaction is caused by the unsaturated unsaturated compound gas and the carbon oxide gas.

Examples of the inert gas include helium gas, argon gas, neon gas, krypton gas, xenon gas, radon gas and the like. Helium gas and argon gas are preferable, and argon gas is particularly preferable.

Further, as the polymerizable unsaturated compound gas,
For example, a compound gas having a double bond, such as ethylene gas and propylene gas, may be mentioned, and ethylene gas is preferable. Further, since the carbon oxide gas has a role of effectively introducing an oxygen functional group into the surface polymer, carbon dioxide gas,
Carbon monoxide is preferred, and carbon dioxide gas is particularly preferred because a surface reactant that is firmly adhered to ETFE is obtained.

The composition of the mixed gas is such that the polymerizable unsaturated compound gas is 1 to 1 with respect to 100 moles of the inert gas.
5 mol and 1 to 20 mol of carbon oxide gas are preferred, and most preferably 3 to 10 mol of polymerizable unsaturated compound gas and 1 mol of carbon oxide gas per 100 mol of inert gas.
１２12 mol. When the amount of the polymerizable unsaturated compound gas and the amount of the carbon oxide gas are larger than the amount of the inert gas, the initial discharge voltage becomes higher and the discharge treatment becomes difficult. In addition, if air is mixed in this atmosphere, it becomes difficult to discharge, so that it is necessary to avoid air.

Further, as a method of the discharge treatment, forms such as corona discharge (spark discharge), plasma discharge and glow discharge can be applied. In each case, the treatment surface is exposed in a gas atmosphere, and a discharge treatment is performed by applying a high-frequency voltage of 3 kHz to 40 kHz between the electrodes. The form of the discharge varies depending on the composition of the mixed gas. As described above, when the amount of the polymerizable unsaturated compound gas and the carbon oxide gas relative to the inert gas increases, the plasma discharge or glow discharge changes to a corona discharge (spark discharge). .

The pressure during the discharge treatment is not particularly limited as long as the mixed gas can be maintained in a gaseous state.
The range may be 1.1 kg / cm ² . Since the surface treatment is performed under substantially atmospheric pressure, it is preferable in that an expensive device is not required. The temperature during the discharge treatment is not particularly limited,
Usually, the temperature may be in the range of 10 to 80 ° C.
~ 60 ° C.

The electric power for the discharge process is 100 to 150
0 W · min / m ² is preferable, and particularly when the surface-treated molded product is dry-laminated with another film using a solvent-type adhesive, 300 W · min / m 2 is required because the adhesive needs to wet the surface. Discharge treatment with ² or more electric powers and water contact angle of 90 ° or less, or JIS K6768
The wettability may be increased to 34 dyn / cm or more by the surface tension (hereinafter, simply referred to as surface tension) according to the wetting test method specified in (1). It should be noted that in the discharge treatment using power of 2000 W · min / m ² or more, the treatment layer becomes thick, and ETFE
It is easy to detach from the molded product, which is not preferable.

Also, the ETF surface-treated according to the present invention
Various adhesives and inks can be used for E-molds. Examples of the adhesive include an adhesive such as a polyester-based adhesive, a urethane-based adhesive, an epoxy-based adhesive, a nylon-based adhesive, an ethylene-vinyl acetate-based adhesive, an acrylic-based adhesive, and a rubber-based adhesive. Can be Examples of the ink include an ink made of a resin contained in the adhesive. Adhesives, inks and the like can be firmly adhered to the surface-treated surface of the ETFE molded product, and peeling can be suppressed until the adhesives and the inks themselves are hydrolyzed or deteriorated by light such as ultraviolet rays.

When the surface-treated ETFE molded product is a sheet, a film, a tube, or the like, a laminate can be formed with another sheet or the like. Specific examples of the laminate include, for example, a sheet made of a resin such as a soft vinyl chloride resin (hereinafter, referred to as a soft PVC), a polyethylene resin, a polypropylene resin, a polycarbonate resin, a urethane resin, a nylon resin, an epoxy resin, a melamine resin, and an acrylic resin. , A film, or a laminate with a tube, or a laminate with a metal plate such as a stainless steel plate, an aluminum plate, an iron plate, or a galvanium steel plate.

These laminates may be laminated via an adhesive, and the substrate to be laminated itself has an adhesive property (for example, ethylene-vinyl acetate resin,
When it is composed of a urethane resin), the resin molded article according to the present invention and the substrate may be firmly bonded by a hot press method.

The amount of the surface functional group can be estimated from the water contact angle. Raw E
The water contact angle of the surface of the TFE molded product is about 102 °. However, in order to be able to apply the adhesive without repelling and to secure the adhesive force between the adhesive and the surface-treated surface mainly by hydrogen bonding, the water contact angle is required. The angle must be 90 ° or less, and the lower the value, the better. In addition, the same type of film adhesive or the functional group of the adhesive is adhered to the base material having a functional group with strong affinity by a hot press via a hot melt film adhesive instead of a solvent type. Also in this case, a film having a low water contact angle, in other words, a film having more surface functional groups has a higher initial adhesion and an adhesion after a boiling water test.

[0033]

Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by these. In addition, the measuring method of the physical property in an Example and a comparative example was performed by the method shown below.

(1) Boiling water test A test piece of the composite laminate bonded with an adhesive was immersed in boiling water, and the change in adhesion after 100 hours and the form of peeling were observed. If the functional groups are sufficiently introduced into the surface, the adhesion before the boiling water test is high and the WB
If L is not generated, the adhesion is maintained even after the boiling water test.

(2) Weather resistance test According to JIS B7753, a sunshine carbon arc lamp type weather resistance test was performed for 6000 hours, an accelerated test was performed under conditions where water and light were directly applied, and the light transmittance before and after the test was measured. The change and the change in water contact angle were measured.

Example 1 One side of an ETFE film (Aflex 50N, manufactured by Asahi Glass) having a thickness of 50 μm was
Argon gas: ethylene gas: carbon dioxide gas (molar ratio) = 1
In a mixed gas atmosphere of 00: 7: 2, discharge treatment was performed at 30 ° C. and atmospheric pressure at a treatment intensity of 300 W · min / m ² to perform surface treatment. The water treatment angle of the surface treatment surface of this surface treatment film is 85 °, and the surface tension is 42 dyn / cm.
Met.

Subsequently, a two-part urethane adhesive (manufactured by Toyobo, Byron 50AS and its curing agent) was applied to the surface-treated surface to a thickness of 10 μm, and a 200 μm soft PVC film was laminated at 70 ° C. A 100 hour boiling water test was performed. The adhesion before the test is 1.5kgf / c
m, the adhesion after the test was 1.4 kgf / cm, and there was almost no decrease in the adhesion. The peeling form at this time was a so-called cohesive failure of the adhesive, in which the adhesive remained on both the ETFE film side and the soft PVC film side before and after the test.

The surface treated film was subjected to a weather resistance test for 6000 hours. The total light transmittance before and after the exposure was 95.2% and 95.0%, respectively, showing almost no decrease. Water contact angle after exposure is 85 °,
The surface tension was not changed at 42 dyn / cm.

Examples 2 to 6 ETFE having a thickness of 50 μm
One surface of a film (manufactured by Asahi Glass, Aflex 50N) was subjected to a surface treatment under the conditions shown in Table 1, and the same test as in Example 1 was performed. In Examples 3 and 6, 200 μm was used.
An ethylene-vinyl acetate hot melt adhesive (Marukabond ME-5, manufactured by Maruhan Chemical Industry Co., Ltd.) was used as an adhesive for lamination with the m-ethylene-vinyl acetate film. Were laminated. Table 1 shows the results.

[Comparative Example 1] The same test as in Example 1 was performed without subjecting an ETFE film (Aflex 50N, manufactured by Asahi Glass) having a thickness of 50 µm to discharge treatment. However, the water contact angle was 102 ° and the surface tension was less than 31 dyn / cm. Subsequently, a two-liquid urethane adhesive (manufactured by Toyobo, Byron 50AS and its hardener) was applied to the surface-treated surface to a thickness of 10 μm, and a 200 μm-thick soft PVC film was laminated at 70 ° C. The force hardly adhered to 100 gf / cm. A weather resistance test was performed on this surface-treated film in accordance with JIS B7753 for 6000 hours. The total light transmittance before and after exposure was 95.2% and 95.2%, respectively, and there was almost no decrease. The water contact angle after the exposure was 102 °, and the surface tension was less than 31 dyn / cm.

Comparative Example 2 One surface of an ETFE film (Aflex 50N, manufactured by Asahi Glass) having a thickness of 50 μm was
In a mixed gas atmosphere of argon gas: ethylene gas (mol%) = 100: 7, discharge treatment was performed at 50 ° C. and atmospheric pressure at a treatment intensity of 300 W · min / m ² . The water contact angle of this surface-treated film was 99 °, and the surface tension was less than 31 dyn / cm.

Subsequently, a two-part urethane adhesive (manufactured by Toyobo, Byron 50AS and its hardener) was applied to the surface-treated surface to a thickness of 10 μm, and a 200 μm-thick soft PVC film was laminated at 70 ° C. , 100 hours boiling water test. The adhesion before the test is 0.2kgf
/ Cm. A weather resistance test was performed on this surface-treated film for 6000 hours. The total light transmittance before and after exposure was 95.2, respectively.
%, 95.0, there is almost no decrease, the water contact angle after exposure is 100 °, and the surface tension is 31 dyn / c.
m and no change was observed.

[Comparative Examples 3 to 14] ETF having a thickness of 50 μm
One surface of an E film (manufactured by Asahi Glass, Aflex 50N) was subjected to a surface treatment under the conditions shown in Tables 2 and 3, and the same test as in Example 1 was performed.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

The surface treatment according to the present invention can efficiently produce only oxygen functional groups such as hydroxyl, carbonyl or carboxyl groups without producing WBL on the surface treated surface of the ETFE molded article. . In addition, this surface treatment is excellent in boiling water and weather resistance of the surface-treated surface, can be applied to a wide range of adhesives, and can obtain an ETFE laminate and printed matter at low cost.

Continuing from the front page (72) Inventor Satoshi Oki 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside the Central Research Laboratory, Asahi Glass Co., Ltd. (72) Inventor Hideaki Miyazawa 3-474-2 Tsukakoshi, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Asahi Glass Co., Ltd.Tamagawa Branch Office (72) Inventor Yukio Mikiri 1150 Hazawacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside

Claims (4)

[Claims] 1. A surface treatment method comprising subjecting an ethylene-tetrafluoroethylene copolymer molded article to a discharge treatment in a mixed gas comprising an inert gas, a polymerizable unsaturated compound gas and a carbon oxide gas. . 2. The proportion of each component of the mixed gas is as follows: inert gas: polymerizable unsaturated compound gas: carbon oxide gas = 100 mol:
The surface treatment method according to claim 1, wherein the amount is 1 to 15 mol: 1 to 20 mol. 3. A mixed gas comprising an argon gas, an ethylene gas and a carbon dioxide gas.
The surface treatment method described. 4. A molded article of an ethylene-tetrafluoroethylene copolymer surface-treated by the surface treatment method according to claim 1, 2 or 3.