JP2007182503A - Method for producing surface-modified film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a surface-modified film in which adhesion between film and coating film is enhanced in a short time and miniaturization and energy saving of apparatus, simplification of operation and securement of operation safety are made possible. <P>SOLUTION: The method for producing the surface-modified film comprises irradiating ultraviolet light having a main peak in the range of 120-260 nm wavelength of ultraviolet light to the film surface to be treated. In the production method, it is preferable to use an excimer lamp emitting ultraviolet light having a main peak when wavelength of the ultraviolet light is 172 nm or a low-pressure mercury lamp emitting ultraviolet light having a main peak when wavelength of the ultraviolet light is 185 nm and 254 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a surface-modified film so that plastic bonding and the like can be easily performed.

  As a surface modification method for activating the film surface, as described in Patent Document 1, a method of immersing in a solution such as an alkali, an acid, or a surfactant and various solvents has been used.

  For example, a polarizing plate used for a liquid crystal display or a plasma display has a structure in which polyvinyl alcohol (PVA) is sandwiched between triacetyl cellulose films from both sides. In order to improve adhesion, saponification treatment with an alkaline solution is performed.

Prior art documents are shown below.
JP 2005-88578 A

  First, the method of immersing the film in a solution such as an alkali, an acid, or a surfactant and various solvents has a long immersion time and is unsuitable for single wafer processing, and thus batch processing is common. Therefore, since a large-sized immersion tank capable of immersing both the transparent plastic member and its fixing member requires 10 to 15 tanks including the drying step, the apparatus is inevitably enlarged and the compactness is lost. At the same time, it requires a lot of power energy to manage the amount of heat and cleanliness associated with drying. In addition, it is also necessary to ensure complicated daily liquid management such as replenishment of volatile components and work safety related to liquid handling.

  In addition, a film that is difficult to adhere to a polar resin composition, such as triacetyl cellulose, is saponified with an alkaline solution. Therefore, there is a problem of waste liquid and a problem that an optical defect is generated in the material due to swelling or the like, and there has been a demand for drying.

  A surface modification method by plasma irradiation has been performed as drying, but the method by plasma irradiation has defects such as a short duration of the modification effect and has not been sufficiently processed.

  Therefore, the present invention solves such problems, the purpose of which is to improve the adhesion between the film and the coating film in a short time, and to make the device compact, energy saving, simple operation, Another object of the present invention is to provide a method for producing a surface-modified film capable of ensuring work safety.

  The invention according to claim 1 is a method for producing a surface-modified film, wherein the surface of the film to be treated is irradiated with ultraviolet rays having a main peak within a wavelength range of 120 to 260 nm.

  The invention according to claim 2 is that the ultraviolet ray has a main peak at a wavelength of 172 nm and is generated using an excimer lamp, or has a main peak at wavelengths of 185 nm and 254 nm and uses a low-pressure mercury lamp. The method for producing a surface-modified film according to claim 1, wherein the surface-modified film is generated.

  The invention according to claim 3 is characterized in that the contact angle with respect to water of the film surface exposed to the active oxygen generated by the ultraviolet rays is 25 degrees or less. It is a manufacturing method.

  Uniform modification is possible by irradiating the film surface with excimer ultraviolet rays or low-pressure ultraviolet rays, and wettability is improved by introducing hydrophilic groups. Moreover, the modification effect on the film surface lasts for a long time.

In the present invention, at least one surface of the film surface is irradiated with excimer ultraviolet light or low-pressure ultraviolet light.
As a method of irradiating such excimer ultraviolet rays or low-pressure ultraviolet rays, there is a method using a transfer system device in addition to a batch type.

  Hereinafter, the present invention will be described in more detail.

  The present invention has found that the film surface is modified by irradiating ultraviolet rays, particularly ultraviolet rays emitted from excimer lamps and low-pressure mercury lamps.

  An excimer lamp in which xenon gas is sealed emits ultraviolet light having a main peak near 172 nm. Ultraviolet light having a wavelength shorter than 175 nm is directly absorbed by oxygen in the atmosphere to generate active oxygen.

The low-pressure mercury lamp emits ultraviolet rays having main peaks mainly around 185 nm and 254 nm. Short wavelength ultraviolet rays around 185 nm are absorbed by oxygen O ₂ in the atmosphere to generate ozone O ₃ . Furthermore, when the ultraviolet rays near 254 nm are absorbed by this ozone, active oxygen O is generated.

The oxidizing action of the active oxygen can be cleaned by decomposing organic substances on the surface of the transparent plastic member into substances such as H ₂ O, CO, CO ₂ , NO ₂ and removing them in a short time.

  It is known that the chemical energy of light is stronger as the wavelength of the light is shorter. These ultraviolet rays in the short wavelength region have energy that can break the bonds of most organic substances. Therefore, by directly acting on the film, it reacts with the active oxygen through bond breaking and free radical generation, and a surface having a hydrophilic group such as a hydroxyl group, a carboxyl group, or a carbonyl group is formed. Activated. Here, the short wavelength means a wavelength of 260 nm or less.

  This method, which can clean and activate the film surface by simply irradiating ultraviolet rays in the short wavelength region for a short time, has a very short processing time, does not cause contamination by processing, and requires a special cleaning process. Therefore, the apparatus is very simple and compact, and is a processing method suitable for single wafer processing and in-line processing. In addition, since the amount of electric power energy used is small compared to other surface modification methods and no organic solvent or water is required, this is an environmentally friendly treatment method and the manufacturing cost can be reduced. In particular, excimer ultraviolet light is extremely efficient because it has a single wavelength having a main peak only in the vicinity of 172 nm.

  Since the coating film and the film surface can be sufficiently adhered and bonded without being disturbed by the non-uniform layer, it is possible to improve the adhesion. Furthermore, uniform modification is possible over the entire film surface, and wettability is improved by the introduction of hydrophilic groups.

  Examples of the film in the present invention include a cellulose polymer film, a polycarbonate polymer film, a polyester polymer film, an acrylic ester polymer film, and an ultraviolet curable acrylic resin. Particularly preferred films include polymethyl methacrylate film and triacetyl cellulose film.

  The types of coating materials used for coating after the start of the surface include water-based coating materials such as PVA and other water-based coating materials, sol-gel coating materials, ultraviolet rays, electron beam curable acrylic materials, epoxy materials, -Thiol system etc. are mentioned.

  Using an excimer ultraviolet irradiation device (UEEX204 manufactured by Iwasaki Electric Co., Ltd.), a triacetylcellulose film (TDY80UL manufactured by Fuji Photo Film) was irradiated with excimer ultraviolet light at an irradiation distance of 3 mm for 90 to 120 seconds to obtain a sample of Example 1. .

  Using a low-pressure mercury lamp ultraviolet irradiation device (OC-2506, manufactured by Iwasaki Electric Co., Ltd.), a triacetyl cellulose film (TDY80UL, manufactured by Fuji Photo Film) is irradiated with low-pressure mercury lamp ultraviolet rays of 25 watts x 4 for 420 to 600 seconds at an irradiation distance of 25 mm. Thus, a sample of Example 2 was obtained.

<Comparative Example 1>
Using a remote type plasma irradiation apparatus, a triacetyl cellulose film (TDY80UL manufactured by Fuji Photo Film) was irradiated with 1 kilowatt 20 KHz plasma for 2.5 to 8.33 seconds at an irradiation distance of 2 mm to obtain a sample of Comparative Example 1. It was.

(Evaluation 1: Contact angle)
The contact angle with the water of the sample of an Example and a comparative example, and an untreated film was measured. The results are shown in Table 1.

According to Table 1, the contact angle between the film irradiated with excimer ultraviolet light and the film irradiated with low pressure mercury lamp ultraviolet light is smaller than that of the film irradiated with plasma. This is because plasma irradiation causes ions to strike the film surface, creating irregularities on the film surface and reducing wettability.
Also, the film irradiated with excimer ultraviolet light has a higher surface modification rate than the film irradiated with low pressure mercury lamp ultraviolet light. This is because the chemical energy of light is strong because of the short wavelength, and because it is a single wavelength having a main peak only in the vicinity of 172 nm, it is possible to efficiently irradiate only the ultraviolet energy necessary for the chemical reaction.

(Evaluation 2: Adhesion)
PVA was applied to the sample of the example and the untreated film by a spin coating method, and then the adhesion was measured.
The adhesion between the film and PVA was evaluated by a cross-cut tape test according to JISK5400. That is, 100 knives are formed on the surface of the base using a knife to make a 1 mm-like cut. Next, a cellophane adhesive tape (according to JIS Z1522) was strongly pressed onto it and quickly pulled away from the surface in the direction of 90 °, and then the remaining grid of the coating film was used as an adhesion evaluation index.

As a result of this adhesion test, the remaining number of samples of Example 1 was 100/100, and sufficient adhesion was obtained.
Further, the remaining number of samples of Example 2 was 100/100, and sufficient adhesion was obtained.
In addition, the untreated film that was not irradiated with ultraviolet rays did not show any adhesion and could not be applied.

(Evaluation 3: Change in contact angle with time)
Immediately after the treatment of Example 1 and Comparative Example 1, the contact angle of water was measured after 1 week and 2 weeks, and the result of FIG. 1 was obtained. The sample of Example 1 was used with a processing time of 120 seconds, and the sample of Comparative Example 1 was used with a processing time of 8.33 seconds.

  In the case of the sample of Example 1, by directly acting on the film surface, it reacts with active oxygen through bond breaking and free radical generation, and has a hydrophilic group such as a hydroxyl group, a carboxyl group, or a carbonyl group. Is formed and the surface is activated. Therefore, the modification effect lasts longer than the sample of Comparative Example 1.

It is the figure showing the relationship between the contact angle with respect to water of the triacetyl cellulose film which surface-modified, and time.

Claims (3)

  A method for producing a surface-modified film, comprising irradiating a surface of a film to be treated with ultraviolet rays having a main peak within a wavelength range of 120 to 260 nm.   The ultraviolet ray has a main peak at a wavelength of 172 nm and is generated using an excimer lamp, or has a main peak at wavelengths of 185 nm and 254 nm and is generated using a low-pressure mercury lamp. The method for producing a surface-modified film according to claim 1.   The method for producing a surface-modified film according to claim 1 or 2, wherein a contact angle of water on the film surface exposed to the active oxygen generated by the ultraviolet rays is 25 degrees or less.

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