JP2010150373A - Surface treating method and adhesion method of film, and method of manufacturing polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make treatment easy by widening a process window in surface treatment of a hardly adhesive resin film such as a TAC film and to stabilize productivity. <P>SOLUTION: A polymerizable monomer is activated by plasma and bonded to the hardly adhesive film 11 (a plasma treatment step). The hardly adhesive resin film 11 is then washed by a washing liquid 59 (a washing step). The polymerizable monomer is preferably acrylic acid or methacrylic acid and more preferably acrylic acid. The washing liquid 59 is an aqueous washing liquid preferably containing ≥90 mass% water and more preferably pure water or ion exchange water. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for treating the surface of a resin film, an adhesion method, and a method for producing a polarizing plate, and in particular, to the hardly adhesive resin film when adhering a hardly adhesive resin film and an easily adhesive resin film. The present invention relates to a surface treatment method performed on the surface.

  A polarizing plate is incorporated in the liquid crystal display device. The polarizing plate is a triacetate cellulose (hereinafter referred to as “TAC” as appropriate) on a polarizing film made of a resin film (hereinafter referred to as “PVA film” as appropriate) containing polyvinyl alcohol (hereinafter referred to as “PVA” as appropriate) as a main component. ) As a main component, and a protective film made of a resin film (hereinafter referred to as “TAC film” as appropriate) is bonded using an adhesive. As the adhesive, water-based adhesives such as polyvinyl alcohol and polyether are used. PVA films have good adhesion to these adhesives, but TAC films do not have good adhesion. Therefore, in general, the TAC film is immersed in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide and saponified prior to bonding. Thereby, the surface of the TAC film is hydrolyzed to increase hydrophilicity, and the adhesive is easily attached to the TAC film.

  As a surface treatment method other than saponification treatment, for example, in Patent Document 1, the surface of an object to be treated is subjected to plasma treatment with a mixed gas of helium and argon under atmospheric pressure, and then acrylic acid is sprayed with a spray gun, and acrylic acid is graft polymerized. And a method for modifying the surface of the object to be processed has been proposed.

In Patent Document 2, an inert gas such as nitrogen or argon and an organic thin film forming gas are mixed, and the mixed gas is plasma-discharged under atmospheric pressure and supplied to the object to be processed. A method for enhancing the performance has been proposed.
Japanese Patent No. 3292924 JP 2006-299000 A

As a result of intensive studies, the inventors have obtained the knowledge that when the surface treatment amount of the TAC film becomes excessive, the adhesiveness is rather poor (see Comparative Examples 1 and 2 below). This suggests the necessity of adjusting the surface treatment amount so as not to be excessive or insufficient. Specifically, the processing is performed with various processing conditions such as the supply flow rate, concentration, and processing time of the process gas within suitable ranges. Therefore, the process window is narrow and management is complicated. If it is out of the preferred range, sufficient adhesion performance cannot be obtained, and the productivity (non-defective product rate) of the final product such as a polarizing plate including a bonded film becomes unstable.
The present invention has been made in view of such circumstances, and facilitates the processing by widening the process window in the surface treatment of difficult-to-adhere resin films such as TAC films, and as a result, production of products such as polarizing plates. The purpose is to stabilize the sex.

As a result of further study and consideration in order to solve the above-mentioned problems, the inventors conducted plasma treatment on a hardly adhesive film such as a TAC film, and then wet-washed with water or the like, regardless of the amount of plasma treatment, The knowledge that the adhesive strength can be stabilized was obtained (see Examples 1 and 2 below).
That is, when a plasma treatment is applied to a difficult-to-adhere film such as a TAC film, a substance that inhibits the adhesion appears on the surface of the hardly-adhesive film, which is presumed to be a factor in lowering the adhesiveness during excessive processing. As an example of the adhesion-inhibiting substance, a plasticizer bleed material contained in a difficult-to-adhere film can be mentioned. This type of bleed material is difficult to adhere, and when the plasma treatment is excessive, the amount of precipitation of the hardly adherent bleed material increases, and as a result, it is considered that the adhesiveness is lowered. On the other hand, this type of bleed product can be easily washed away with a cleaning liquid such as water.

  For example, a TAC film generally contains about 10% of triphenyl phosphate (TPP) as a plasticizer. The inventors have confirmed that when the TAC film is irradiated with nitrogen plasma, the bleed material which appears to be derived from TPP appears on the surface of the TAC film in the form of fine spots. Then, when the surface of the TAC film was washed with water, it was confirmed that the bleed material was removed from the surface of the TAC film.

As another example of the adhesion inhibitor, an ion-binding salt that is generated as a secondary reaction by a reaction during plasma treatment can be considered. Examples of this type of salt include ammonium cyanate (NH ₄ OCN), urea (H ₂ NCONH ₂ ), ammonium acetate (CH ₃ COONH ₄ ), and the like. The inventors analyzed the plasma-treated TAC film by TOF-SIMS (Time of Flight Secondary Ion Mass Spectrometry) analysis, and confirmed the generation of ions presumed to be derived from any of the above salts. This type of salt is readily soluble in aqueous solvents such as water.

The film surface treatment method according to the present invention is based on the above findings, and is a method for treating the surface of a hardly adhesive resin film to be bonded to an easily adhesive resin film,
A plasma treatment step in which a polymerizable monomer is activated by plasma to react with the hardly adhesive resin film;
And a cleaning step of cleaning the hardly adhesive resin film with a cleaning liquid after the plasma treatment step.
According to the present invention, even when the plasma treatment process is over-treated, the adhesiveness can be recovered by washing, and a stable adhesive strength can be obtained regardless of the amount of treatment. Therefore, the process window in the plasma processing step can be widened, and it is not necessary to strictly adjust various processing conditions such as the supply flow rate, concentration, and processing time of the process gas, and the surface treatment can be easily performed. The processing quality can be stabilized, and as a result, the productivity of the product including the adhered film can be stabilized.

  The difficult-to-adhere resin film refers to a film having relatively lower adhesiveness to the adhesive than the counterpart film adhered to the film. The easy-adhesive resin film refers to a film having relatively higher adhesiveness to the adhesive than the counterpart film adhered to the film. The same film may become a difficult-to-adhere resin film or an easily-adhesive resin film depending on the opposite film to be adhered.

The hardly adhesive resin film is preferably a nonpolar resin film.
As main components of the hardly adhesive resin film, triacetate cellulose (TAC), polypropylene (PP), polyethylene (PE), cycloolefin polymer (COP), cycloolefin copolymer (COC), polyethylene terephthalate (PET), Examples thereof include polymethyl methacrylate (PMMA) and polyimide (PI).

  As a main component of the said easily-adhesive resin film, polyvinyl alcohol (PVA) is mentioned, for example.

  Examples of the polymerizable monomer include monomers having an unsaturated bond and a predetermined functional group. The predetermined functional group is preferably selected from a hydroxyl group, a carboxyl group, an acetyl group, a glycidyl group, an epoxy group, an ester group having 1 to 10 carbon atoms, a sulfone group, and an aldehyde group. A hydrophilic group is preferred.

Examples of the monomer having an unsaturated bond and a hydroxyl group include ethylene glycol methacrylate, allyl alcohol, and hydroxyethyl methacrylate.
Examples of the monomer having an unsaturated bond and a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and 2-methacryloylpropionic acid.
Examples of the monomer having an unsaturated bond and an acetyl group include vinyl acetate.
Examples of the monomer having an unsaturated bond and a glycidyl group include glycidyl methacrylate.
Monomers having an unsaturated bond and an ester group include methyl acrylate, ethyl acrylate, butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid. Examples include butyl, t-butyl methacrylate, isopropyl methacrylate, and 2-ethyl methacrylate.
Examples of the monomer having an unsaturated bond and an aldehyde group include acrylic aldehyde and crotonaldehyde.

Preferably, the polymerizable monomer is a monomer having an ethylenically unsaturated double bond and a carboxyl group. Examples of such monomers include acrylic acid (CH ₂ ═CHCOOH) and methacrylic acid (CH ₂ ═C (CH ₃ ) COOH).

The polymerizable monomer may be conveyed by a carrier gas. The carrier gas is preferably selected from an inert gas such as nitrogen, argon or helium. From the economical viewpoint, it is preferable to use nitrogen as the carrier gas.
Many polymerizable monomers such as acrylic acid and methacrylic acid are in a liquid phase at normal temperature and pressure. Such a polymerizable monomer may be vaporized in a carrier gas such as an inert gas to obtain a polymerizable monomer-containing gas composed of a mixed gas of a polymerizable monomer vapor and a carrier gas. As a method of vaporizing the polymerizable monomer into the carrier gas, a method of extruding a saturated vapor on the surface of the polymerizable monomer solution with the carrier gas, a method of bubbling the carrier gas into the polymerizable monomer solution, a polymerizable monomer solution For example, a method of promoting evaporation by heating can be used. Extrusion and heating, or bubbling and heating may be used in combination.

  When heating and vaporizing, it is preferable to select a polymerizable monomer having a boiling point of 300 ° C. or less in consideration of the burden on the heater. Moreover, it is preferable to select a polymerizable monomer that does not decompose (chemically change) by heating.

  In the plasma treatment process, plasma is used to activate the polymerizable monomer. For example, an electric field is applied between a pair of electrodes to generate a discharge, and a plasma generating gas is introduced into a discharge space between the electrodes to generate plasma. As the plasma generating gas, it is preferable to use an inert gas such as nitrogen, argon, or helium. This plasma activates the polymerizable monomer. Activation of the polymerizable monomer includes cleavage, polymerization, and decomposition of the polymerizable monomer. The activated polymerizable monomer reacts with the hardly adhesive resin film. For example, the bond of C—C, C—O, C—H, etc. on the surface of the hardly-adhesive resin film is cut by contact with plasma gas or by irradiation with plasma light, and a polymer of a polymerizable monomer is formed at the bond cutting portion. Is considered to be graft polymerized. Or it is thought that the functional group decomposed | disassembled from the polymerizable monomer couple | bonds with a bond cutting part. Thereby, it is considered that an adhesion promoting layer is formed on the surface of the hardly adhesive resin film. In addition, as described above, it is presumed that an adhesion inhibitory substance is also generated.

  In the plasma treatment step, a mixed gas of polymerizable monomer vapor and plasma generating gas may be introduced into the discharge space and brought into contact with the hardly adhesive resin film. In this case, the polymerizable monomer vapor is activated directly in the discharge space. Alternatively, a gas containing a polymerizable monomer vapor is supplied to the hardly-adhesive resin film to be supported (condensed, etc.) on the surface of the hardly-adhesive resin film, and then for plasma generation different from the above-mentioned polymerizable monomer-containing gas The gas may be turned into plasma and brought into contact with the portion of the hardly adhesive resin film on which the polymerizable monomer is supported. Alternatively, the plasma generating gas may be converted into plasma and contacted with the hardly adhesive resin film, and then the polymerizable monomer may be contacted with the plasma contact portion of the hardly adhesive resin film. The plasma generating gas and the carrier gas of the polymerizable monomer vapor may be composed of the same component (for example, nitrogen), and the carrier gas may also serve as the plasma generating gas.

In the plasma treatment step, it is preferable that the hardly adhesive film temperature is room temperature or higher. Here, the room temperature is generally 20 to 25 ° C., and more generally 25 ° C.
In the plasma treatment step, the temperature of the hardly adhesive film is preferably 5 ° C. or more and more preferably 10 ° C. or more than the temperature at which the polymerizable monomer vapor is blown. Thereby, the polymerizable monomer can be reliably supported (condensed or the like) on the hardly-adhesive resin film, and as a result, the polymer of the polymerizable monomer can be reliably bonded to the surface molecules of the hardly-adhesive resin film.
The temperature of the polymerizable monomer-containing gas is preferably less than the flash point of the polymerizable monomer. Incidentally, the flash point of acrylic acid is 54 ° C. The flash point of methacrylic acid is 77 ° C. The ignition point of acrylic acid is 360 ° C. The ignition point of methacrylic acid is 360 ° C.

  The oxygen concentration (volume concentration) in the discharge space is preferably 0 to 3000 ppm, and more preferably 2000 ppm or less. Thereby, sufficient adhesive strength can be obtained.

The plasma treatment step is preferably performed under a pressure near atmospheric pressure. Here, the vicinity of the atmospheric pressure refers to a range of 1.013 × 10 ^{4 to} 50.663 × 10 ⁴ Pa, and considering the ease of pressure adjustment and the simplification of the apparatus configuration, 1.333 × 10 ⁴ to 10.664 × 10 ⁴ Pa is preferable, and 9.331 × 10 ^{4 to} 10.9797 × 10 ⁴ Pa is more preferable.
The plasma treatment process may be performed under vacuum.

In the cleaning step, the cleaning liquid is preferably an aqueous cleaning liquid containing 90% by mass or more of water, and more preferably pure water or ion-exchanged water.
The aqueous cleaning liquid has high fluidity and can reliably remove the adhesion-inhibiting substance from the surface of the hardly adhesive resin film. By using pure water or ion-exchanged water as the aqueous cleaning liquid, the processing cost can be reduced, and when the adhesion inhibitor is made of an ionic salt, it can be easily dissolved.

The film adhesion method according to the present invention includes an adhesion step of adhering the hardly adhesive resin film treated by the film surface treatment method and the easily adhesive resin film with an adhesive.
The adhesiveness of the hardly adhesive resin film that has undergone the above film surface treatment method is reliably improved, and can be reliably adhered to the easily adhesive resin film.

  The adhesive is not particularly limited, and a polyvinyl alcohol-based adhesive liquid mainly composed of a polyvinyl alcohol aqueous solution, a polyvinyl butyral solution, etc., a vinyl polymer latex based on butyl acrylate, a polyolefin polyol, etc. Olefin water-based adhesives, polyether adhesives, and the like are mainly used, but it is more preferable to use polyvinyl alcohol adhesives mainly composed of a polyvinyl alcohol aqueous solution. In the case where the hardly adhesive resin film is used as an optical film such as a polarizing plate, the adhesive is preferably transparent. A water-based adhesive can be used as the transparent adhesive.

You may decide to perform the said adhesion process after the said washing | cleaning process. In this case, a dewatering process for removing the cleaning liquid may be interposed between the cleaning process and the bonding process.
The cleaning liquid contains an adhesive component, and in parallel with the cleaning process, the hardly adhesive resin film and the easily adhesive resin film are bonded together with a part of the cleaning liquid used in the cleaning process interposed therebetween. Also good. Thereby, two films can be adhere | attached with the adhesive agent component in the washing | cleaning liquid pinched | interposed between these two films. Therefore, the cleaning process and the bonding process can be performed simultaneously. Therefore, the number of processes can be reduced and the working time can be shortened.

The cleaning liquid is preferably an aqueous polyvinyl alcohol solution containing less than 10% by mass of polyvinyl alcohol as the adhesive component.
More preferably, the cleaning liquid is an aqueous polyvinyl alcohol solution containing less than 5% by mass of polyvinyl alcohol as the adhesive component.

The polarizing plate production method according to the present invention is a production method of a polarizing plate using the film adhesion method, wherein the hardly adhesive resin film is a protective film containing triacetate cellulose as a main component, and the easy adhesion property. The resin film is a polarizing film containing polyvinyl alcohol as a main component.
By adopting the above surface treatment method, it is possible to ensure adhesiveness, and thus to stabilize the productivity of the polarizing plate.

  According to the present invention, the process window in the plasma processing step can be widened, and the processing conditions can be easily set. Stable adhesive strength can be obtained regardless of the amount of treatment, treatment quality can be stabilized, and productivity of a product such as a polarizing plate can be stabilized.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 6 shows a polarizing plate 10 for a liquid crystal display produced by using the surface treatment method according to the embodiment of the present invention. As illustrated in FIG. 6A, the polarizing plate 10 includes a polarizing film 12 and a pair of protective films 11 laminated on both surfaces of the polarizing film 12.

  The protective film 11 is comprised with the TAC film which has a triacetate cellulose (TAC) as a main component. The content of triacetate cellulose in the TAC film 11 is 90% by mass or more. The TAC film 11 may further contain about 3 to 10% by mass of a plasticizer such as triphenyl phosphate (TPP) or phosphate ester, or may contain an ultraviolet absorber. The thickness of the TAC film 11 is not particularly limited, and is, for example, several tens of μm to several tens of μm. The manufacturing method of the TAC film 11 is not particularly limited, and is manufactured by, for example, a casting method.

  The polarizing film 12 is comprised by the PVA film 12 which has polyvinyl alcohol (PVA) as a main component.

  The TAC film 11 and the PVA film 12 are bonded by an adhesive 13. Although there is no limitation in particular as the adhesive agent 13, Considering applying to the optical film 10, it is preferable to use a transparent aqueous adhesive. As water-based adhesives, polyvinyl alcohol-based adhesive liquids mainly composed of polyvinyl alcohol aqueous solution, polyvinyl butyral solution, etc., vinyl-based polymer latexes based on butyl acrylate, etc., olefins mainly composed of polyolefin-based polyols, etc. Examples thereof include water-based adhesives and polyether-based adhesives. As the adhesive 13, it is more preferable to use a polyvinyl alcohol-based adhesive mainly composed of an aqueous polyvinyl alcohol solution.

  In the polarizing plate 10 shown in FIG. 6B, a hard coat layer 14 is laminated as a functional layer on the front side surface of one TAC film 11 (the surface opposite to the adhesive surface with the PVA film 12). Instead of the hard coat layer 14, an AR layer and other functional layers may be laminated.

  The TAC film 11 has low adhesiveness with the adhesive 13 and constitutes a hardly adhesive resin film. The PVA film 12 has high adhesiveness with the adhesive 13 and constitutes an easily adhesive resin film. The difficult-to-adhere TAC film 11 is subjected to a surface treatment for improving adhesiveness when adhering to the easily-adhesive PVA film 12.

  FIG. 1 shows a surface treatment apparatus 1 used for the surface treatment. The surface treatment apparatus 1 includes a plasma processing unit 2, a process gas supply system 3, and a cleaning unit 5. The plasma processing unit 2 includes a pair of electrodes 21R and 22R. These electrodes 21R and 22R form a roll shape (cylindrical shape) and are opposed to the left and right.

  One roll electrode 21 </ b> R is connected to the high voltage terminal of the power source 23. The other roll electrode 22R is electrically grounded. By supplying voltage from the power source 23, an electric field is formed between the electrodes 21R and 22R, and the space 20a around the narrowest portion between the roll electrodes 21R and 22R becomes a discharge space of almost atmospheric pressure. The voltage from the power source 23 and the electric field between the electrodes 21R and 22R are in the form of pulses, for example. The rise time and / or fall time of the pulse is preferably 10 μs or less, the electric field strength is preferably 10 to 1000 kV / cm, and the frequency is preferably 0.5 to 100 kHz. The applied voltage and electric field are not limited to pulsed intermittent waves, and may be continuous waves such as sine waves.

  The roll electrodes 21R and 22R also function as support means and transport means for the TAC film 11 that is the object to be processed. The continuous sheet-like TAC film 11 is straddled across the two roll electrodes 21R and 22R and is wound around the upper peripheral surface of each roll electrode 21R and 22R, for example, about a half turn. The TAC film 11 between the roll electrodes 21R and 22R passes through the discharge space 20a and extends downward, and is folded around the pair of folding rolls 27 and 27. The TAC film 11 is conveyed in one direction (right direction) by the rotation of the two roll electrodes 21R and 22R.

  A film temperature adjusting means 28 is incorporated in each roll electrode 21R, 22R. The film temperature adjusting means 28 is constituted by a temperature adjustment path. A temperature control medium having a predetermined temperature flows through the temperature control path in the roll electrodes 21R and 22R. For example, water is used as the temperature control medium. Thereby, the temperature of the roll electrodes 21R and 22R can be adjusted, and further, the temperature of the portion of the TAC film 11 in contact with the roll electrodes 21R and 22R can be adjusted. The temperature of the TAC film 11 is preferably room temperature or higher. Here, the room temperature is generally 20 to 25 ° C., and more generally 25 ° C.

Next, the process gas supply system 3 will be described.
The process gas supply system 3 includes a polymerizable monomer supply source 30 and an inert gas supply source 31. The polymerizable monomer supply source 30 is composed of a constant temperature container (a constant temperature bath). A polymerizable monomer is stored in the thermostatic container 30 as a reaction component for the surface treatment. The polymerizable monomer preferably has an unsaturated bond and a predetermined functional group, and more preferably has hydrophilicity. More preferably, acrylic acid or methacrylic acid is used as the polymerizable monomer. Here, acrylic acid (CH ₂ ═CHCOOH) is used as the polymerizable monomer. Acrylic acid is a hydrophilic polymerizable monomer having an ethylenically unsaturated double bond and a carboxyl group. Acrylic acid is contained in the thermostatic container 30 in a liquid state. In FIG. 1, liquid acrylic acid is indicated by “Ac”. A saturated vapor of acrylic acid evaporated from the liquid acrylic acid Ac is present in a portion above the liquid level of the liquid acrylic acid Ac in the thermostatic container 30.

  A constant temperature vessel 30 incorporates a heater 32 as a vaporizing means. The liquid acrylic acid Ac in the container 20 is heated by the heater 32 and vaporized. The amount of acrylic acid vaporized can be adjusted by the heating temperature of the liquid acrylic acid Ac. The heating temperature of the acrylic acid Ac is preferably 150 ° C. or less, more preferably less than the flash point of acrylic acid (54 ° C.), considering that the acrylic acid vapor is explosive, and room temperature (25 ° C) to about 80 ° C, more preferably about room temperature (25 ° C) to about 50 ° C in view of the flash point. The heater 32 may be omitted when the vaporization amount of acrylic acid satisfies the required amount even near room temperature.

The inert gas supply source 31 is filled with an inert gas. The inert gas has a role as a carrier gas for transporting the polymerizable monomer vapor and a role as a plasma generating gas for generating plasma in the discharge space 20a. Here, nitrogen gas is used as the inert gas, but other inert gases such as argon and helium may be used in addition to the nitrogen gas.
A carrier gas or a plasma generating gas containing oxygen gas such as air is not desirable because it inhibits the reactivity of the polymerizable monomer.

  An inert gas supply path 33 extends from the inert gas supply source 31. An inert gas supply path 33 is branched into a plasma generation gas path 34 and a carrier path 35. The passages 34 and 35 are provided with flow rate adjusting means 34v and 35v, respectively. The flow rate adjusting means 34v and 35v are configured by a mass flow controller, a flow rate control valve, or the like. The flow rate adjusting means 34v and 35v adjust the diversion ratio of the inert gas to the paths 34 and 35.

A carrier path 35 is connected to the thermostatic container 30. The leading end of the carrier path 35 is inserted into the thermostatic container 30 and opened, and is located in a portion above the liquid level of the acrylic acid Ac.
The tip of the carrier path 35 may be extended to the inside of the acrylic acid Ac liquid, and nitrogen gas may be bubbled in the acrylic acid Ac.

  A polymerizable monomer vapor path 36 extends from the upper portion of the thermostatic container 30. A plasma generation gas passage 34 joins the polymerizable monomer vapor passage 36. A process gas path 37 extends to the plasma processing unit 2 from the junction of these paths 34 and 36. A gas temperature adjusting means 38 is provided in the polymerizable monomer vapor path 36 and the process gas path 37. The gas temperature control means 38 is constituted by a ribbon heater, for example, and covers the outer circumference of the pipes constituting the polymerizable monomer vapor path 36 and the process gas path 37 over the entire length. The temperature of the gas passing through the polymerizable monomer vapor path 36 and the process gas path 37 can be adjusted by the gas temperature adjusting means 38.

  A process gas nozzle 39 is provided at the tip of the process gas path 37. The process gas nozzle 39 is disposed in the upper part between the pair of roll electrodes 21R and 22R. The opening at the tip of the process gas nozzle 39 is directed downward and faces the discharge space 20a. The front end portion of the process gas nozzle 39 becomes thinner as it goes downward, and is inserted into a gradually narrowing portion between the roll electrodes 21R and 22R.

  Although not shown in detail, the process gas nozzle 39 extends substantially the same as or longer than the width of the TAC film 11 in a direction orthogonal to the paper surface of FIG. Inside the process gas nozzle 39, a rectification path is formed that uniformly disperses the gas from the process gas supply path 37 in the longitudinal direction of the process gas nozzle 39 (in the direction orthogonal to the plane of FIG. 1). The air outlet at the tip of the process gas nozzle 39 is connected to this rectifying path. The blowout port of the process gas nozzle 39 has a slit shape extending in a direction orthogonal to the paper surface of FIG. The outlet of the process gas nozzle 39 may have a number of small holes arranged at intervals in a direction perpendicular to the paper surface of FIG.

  Further, a temperature control path (not shown) is formed inside the process gas nozzle 39. A temperature control medium having a predetermined temperature is passed through the temperature control path. For example, water is used as the temperature control medium. The structure of the process gas nozzle 39 can be maintained at a predetermined temperature by the temperature control medium, and the temperature of the gas passing through the process gas nozzle 39 can be adjusted, and the temperature of the gas blown out from the process gas nozzle 39 can be adjusted.

  A cleaning unit 5 and a liquid removal unit 6 are provided on the transport path of the TAC film 11 on the downstream side (right side in FIG. 1) from the plasma processing unit 2. The cleaning unit 5 includes a cleaning liquid supply source 50 and a cleaning liquid spray nozzle 52. The cleaning liquid 59 of the supply source 50 is supplied to the spray nozzle 52 through the supply path 51. The spray nozzle 52 sprays the cleaning liquid 59 toward the TAC film 11.

  As the cleaning liquid 59, it is preferable to use an aqueous cleaning liquid containing, for example, 90% or more of water, and it is more preferable to use substantially 100% water that does not contain impurities or ions such as pure water or ion-exchanged water. Here, ion exchange water is used as the cleaning liquid 59. Here, the ion-exchanged water is water obtained by cleaning tap water or industrial water through a filter.

  A liquid removal unit 6 is provided on the downstream side of the cleaning unit 5 along the conveyance direction of the TAC film 11. The liquid removal unit 6 includes a liquid supply source 60 for liquid removal and a liquid discharge nozzle 62. The liquid removal gas supply source 60 pressurizes and stores, for example, nitrogen gas as a liquid removal gas. The compressed nitrogen gas from the supply source 60 is jetted from the liquid removal nozzle 62 to the TAC film 11 through the supply path 61. Instead of nitrogen gas, other gas such as air may be used as the degassing gas. The degassing gas is preferably a dry gas. The inert gas supply source 31 may also serve as the degassing gas supply source 60.

A method for surface-treating the TAC film 11 and further manufacturing the polarizing plate 10 using the film surface treatment apparatus 1 having the above configuration will be described.
[Process gas supply process]
Nitrogen gas from the inert gas supply source 31 is distributed from the inert gas supply path 33 to the plasma generation gas path 34 and the carrier path 35. The distribution ratio is adjusted by the flow rate adjusting means 34v, 35v. Nitrogen gas divided into the plasma generating gas path 34 is introduced into the thermostatic container 30, and the acrylic acid vapor above the liquid acrylic acid level in the thermostatic container 30 is pushed out to the polymerizable monomer vapor path 36. In the process gas path 37, the gas (nitrogen + acrylic acid vapor) from the polymerizable monomer vapor path 36 and the nitrogen gas from the plasma generation gas path 34 are mixed to generate a process gas. The concentration of acrylic acid in the process gas (acrylic acid + nitrogen) is preferably 2% or less, more preferably about 1%. The concentration of the process gas can be adjusted by the distribution ratio of nitrogen gas to the two paths 34 and 35 and the heating temperature of acrylic acid by the heater 32. This process gas is sent to the process gas nozzle 39 via the process gas path 37. The process gas is made uniform in the width direction of the TAC film 11 (the direction orthogonal to the plane of FIG. 1) at the process gas nozzle 39 and then blown out into the discharge space 20a.

[Plasma treatment process]
By supplying a voltage from the power source 23, an atmospheric pressure discharge is formed between the electrodes 21R and 22R, and the interelectrode space 20a becomes a discharge space. Thereby, nitrogen in the process gas is turned into plasma and acrylic acid vapor is activated, and acrylic acid and the surface molecules of the TAC film 11 react and chemically bond. For example, activation of acrylic acid includes double bond cleavage, polymerization and the like. Further, the contact of the surface molecules of the TAC film 11 such as C—C, C—O, C—H is cut by contact of the TAC film 11 with nitrogen plasma or irradiation of ultraviolet light (337 nm) from the nitrogen plasma. . It is considered that a polymer of acrylic acid is bonded (graft polymerization) to this bond cutting part, or a COOH group decomposed from acrylic acid is bonded. Thereby, an adhesion promoting layer is formed on the surface of the TAC film 11.

  On the other hand, when the TAC film 11 is irradiated with plasma, the plasticizer in the TAC film 11 oozes out to the surface of the TAC film 11 and becomes a bleed material in the form of solid fine particles. Moreover, ionic salt is produced | generated by the plasma irradiation to the TAC film 11. FIG. These bleeds and salts become adhesion inhibitors.

[Temperature control process]
Further, the temperature of the gas passing through the polymerizable monomer vapor path 36 and the process gas path 37 is adjusted by the gas temperature adjusting means 38 as desired. In addition, the temperature of the process gas passing through the process gas nozzle 39 is adjusted as desired by a temperature control path in the process gas nozzle 39. Thereby, the temperature at which the process gas is blown out from the process gas nozzle 39 (hereinafter referred to as “blowing temperature”) can be set to the set temperature. The upper limit of the blowing temperature is preferably set in a range where the TAC film 11 does not undergo thermal deformation such as swelling. The limit temperature at which the TAC film 11 does not undergo thermal deformation such as swelling is, for example, about 80 ° C., although it depends on the processing conditions. The lower limit of the blowing temperature is preferably room temperature or higher from the viewpoint of preventing condensation in the gas passages 36 and 37 and the nozzle 39. The blowing temperature is preferably about 35 to 80 ° C, more preferably about 40 to 50 ° C.

  At the same time, the temperature of the portion of the TAC film 11 in contact with the roll electrodes 21R and 22R (hereinafter referred to as “film temperature”) is maintained at a desired temperature lower than the process gas blowing temperature by the film temperature adjusting means 28. Preferably, the film temperature is 5 ° C. lower than the blowing temperature. More preferably, the film temperature is set to be 10 ° C. or more lower than the blowing temperature. By controlling the temperature, acrylic acid can be reliably condensed (supported) on the surface of the TAC film 11, and as a result, an adhesion promoting layer containing a graft polymer of acrylic acid can be reliably formed on the surface of the TAC film 11. Can do.

[Conveying process]
In parallel with the process gas supply step and the plasma treatment step, the roll electrodes 21R and 22R are continuously rotated clockwise in FIG. 1 to feed the TAC film 11 in the right direction. Each point (processing place) of the TAC film 11 is wound around the roll electrode 21R, passes through the discharge space 20a immediately before leaving the roll electrode 21R, is folded back by the folding rolls 27 and 27, and is then rolled 22R. And pass through the discharge space 20a again. Each point (processing place) of the TAC film 11 is subjected to plasma processing every time it passes through the discharge space 20a. Therefore, the TAC film 11 can be surface-treated twice in one discharge space 20a.

[Washing process]
Thereafter, the TAC film 11 is sent to the cleaning unit 5, and the cleaning liquid 59 made of ion exchange water is sprayed onto the TAC film 11 from the spray nozzle 52. Thereby, the adhesion inhibiting substance on the surface of the TAC film 11 can be washed away. The bleed material derived from the plasticizer in the TAC film 11 can be easily removed from the surface of the TAC film 11 by the flow of the cleaning liquid 59. The ionic salt is easily dissolved in the ion exchange water, and can be easily removed from the surface of the TAC film 11.

[Dehydration (draining) process]
Thereafter, the TAC film 11 is sent to the liquid removal unit 6, and compressed nitrogen gas is blown onto the TAC film 11 from the liquid removal nozzle 62. By virtue of this compressed nitrogen gas, the surface of the TAC film 11 after washing away the adhesion-inhibiting substance can be drained (drained).

[Adhesion process]
The TAC film 11 of the hardly adhesive resin surface-treated as described above is adhered to the PVA film 12 of the easily adhesive resin by the adhesive 13. Thereby, the polarizing plate 10 can be obtained. Prior to bonding, the TAC film 11 is subjected to the above-described surface treatment, whereby the adhesiveness of the TAC film 11 can be improved and the TAC film 11 can be firmly bonded to the PVA film 12. Thereby, productivity (non-defective rate etc.) of the polarizing plate 10 can be stabilized.

Next, a surface treatment apparatus according to another embodiment of the present invention will be described. In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
The cleaning step can be performed by various methods and apparatuses. FIG. 2 shows an embodiment according to a modification of the cleaning unit 5.
A cleaning container 53 is provided in the cleaning unit 5 shown in FIG. A cleaning liquid 59 such as ion exchange water is stored in the cleaning container 53. The TAC film 11 is passed through the cleaning liquid 59 in the container 53. Thereby, the adhesion inhibiting substance on the surface of the TAC film 11 can be removed. The cleaning liquid in the container 53 may be constantly supplied and discharged, or may be replaced every certain period.

  In the cleaning section 5 shown in FIG. 2B, a sponge roll 54, a transfer roll 55, and a cleaning liquid supply nozzle 56 are provided. A supply nozzle 56 is connected to the cleaning liquid supply source 50. The supply nozzle 56 drops the cleaning liquid 59 from the cleaning liquid supply source 50 onto the sponge roll 54. Accordingly, the sponge roll 54 contains a cleaning liquid. The sponge roll 54 is pressed against the TAC film 11 and rotates as the TAC film 11 moves. At the contact portion between the TAC film 11 and the sponge roll 54, the adhesion-inhibiting substance on the surface of the TAC film 11 moves to the cleaning liquid in the sponge roll 54.

  The transfer roll 55 is pressed against the sponge roll 54, and the transfer roll 55 rotates as the sponge roll 54 rotates. The adhesion inhibiting substance moves from the sponge roll 54 to the transfer roll 55 and is removed.

  FIG. 3 shows a second embodiment according to a modification of the electrode structure of the plasma processing unit 2. The electrode structure of the plasma processing unit 2 in the figure is composed of parallel plate electrodes 21 and 22 which are paired up and down. A power source 23 is connected to the upper plate electrode 21. The lower plate electrode 22 is electrically grounded. A discharge space 20 a is formed between the upper and lower electrodes 21 and 22. A sheet-like TAC film 11 is placed on the lower ground electrode 22. The ground electrode 22 also serves as a stage that supports the film to be processed.

  A process gas nozzle 39 is disposed on one side of the upper electrode 21 (left side in FIG. 3). The process gas nozzle 39 introduces process gas (acrylic acid vapor + nitrogen) into the discharge space 20a. This process gas is turned into plasma in the discharge space 20 a and comes into contact with the TAC film 11. Thereby, the surface of the TAC film 11 is plasma-treated.

  A suction nozzle 42 is provided on the side of the upper electrode 21 opposite to the process gas nozzle 39 side (right side in FIG. 3). The suction nozzle 42 is connected to the exhaust means 40 via the suction path 41. The exhaust means 40 includes an exhaust pump and an abatement mechanism. The treated gas that has passed through the discharge space 20 a is sucked into the suction nozzle 42 and discharged from the exhaust means 40.

  In the process gas supply system 3 of the second embodiment, there are no gas paths 34, 35, and 36 (FIG. 1). The inert gas supply path 33 is directly connected to the constant temperature container 30 without branching. The upstream end of the process gas path 37 is directly connected to the constant temperature container 30.

  A movement mechanism 26 is connected to the lower electrode 22. The moving mechanism 26 moves the electrode 22 and thus the TAC film 11 to the left and right relative to the upper electrode 21. Thereby, the whole TAC film 11 can be processed. The moving mechanism 26 may be connected to the upper electrode 21 and the upper electrode 21 may be moved relative to the TAC film 11.

  In the form of FIG. 3, the sheet-like TAC film 11 is subjected to plasma processing in the plasma processing unit 2, and then taken out from the electrode 22 and cleaned in a separately provided cleaning unit. The sheet-like TAC film 11 may be cleaned by the cleaning liquid spray nozzle 52 (FIG. 1), the cleaning liquid container 53 (FIG. 2A), or the sponge roll 54 (FIG. 2B). )).

  FIG. 4 shows an embodiment according to a modification of the process gas supply system 3. In this embodiment, the supply line for the plasma generating gas (nitrogen) and the supply line for the polymerizable monomer vapor-containing gas (acrylic acid vapor + nitrogen) are separated.

  A plasma generation gas path 34 branched from the inert gas supply path 33 extends to the plasma processing unit 2 without joining the polymerizable monomer vapor path 36. A plasma generation gas nozzle 39 </ b> X is connected to the tip of the plasma generation gas path 34. The tip of the nozzle 39X faces the discharge space 20a. The shape, structure, and arrangement of the nozzle 39X are substantially the same as those of the process gas nozzle 39 of the first embodiment (FIG. 1). However, the plasma generation gas nozzle 39X is not provided with a temperature control path therein. Further, the gas temperature adjusting means 38 is not provided in the plasma generating gas path 34.

  A polymerizable monomer vapor path 36 is drawn out from the thermostatic container 30. The polymerizable monomer vapor path 36 extends to the plasma processing unit 2 without joining the plasma generation gas path 34. A polymerizable monomer-containing gas nozzle 39Y is connected to the tip of the polymerizable monomer vapor path 36. The nozzle 39Y is disposed so as to be slightly upstream from the plasma generating gas nozzle 39X along the conveying direction of the TAC film 11, and to face the peripheral surface slightly above the discharge space 20a of the roll electrode 21R.

  The opposite portions of the roll electrodes 21R and 22R including the discharge space 20a are surrounded by the chamber 8. At least tip portions of the plasma generating gas nozzle 39X and the polymerizable monomer-containing gas nozzle 39Y are accommodated in the chamber 8. A replacement gas supply source 80 is connected to the chamber 8 via a replacement gas supply path 81. The replacement gas supply source 80 stores nitrogen as an inert gas. Further, the chamber 8 is connected to a replacement exhaust means 82 via a replacement suction path 83. The base end portion of the suction path 83 is disposed between the plasma generating gas nozzle 39X and the polymerizable monomer-containing gas nozzle 39Y.

  In this embodiment, the acrylic acid vapor carried by nitrogen is ejected from the polymerizable monomer-containing gas nozzle 39Y via the polymerizable monomer vapor path 36. The acrylic acid vapor is carried (condensed) in contact with the TAC film 11, and an acrylic acid condensed layer is formed on the surface of the TAC film 11. Subsequently, the acrylic acid condensed portion of the TAC film 11 is sent to the discharge space 20a. In the discharge space 20a, nitrogen that has passed through the plasma generation gas passage 34 is blown out from the plasma generation gas nozzle 39X to be converted into plasma. This plasma nitrogen is brought into contact with the TAC film 11 and activates the acrylic acid carried on the TAC film 11. Thereby, the adhesion promotion layer which consists of a graft polymer of acrylic acid etc. on the surface of the TAC film 11 can be formed.

  Further, nitrogen from the replacement gas supply source 80 is introduced into the chamber 8 through the supply path 81. In addition, the gas in the chamber 8 is exhausted from the replacement exhaust means 82 via the suction path 83. Thereby, the atmospheric gas in the chamber 8 can always be replaced with nitrogen. In particular, the atmospheric gas in the space around the TAC film 11 between the tip of the polymerizable monomer-containing gas nozzle 39Y and the discharge space 20a can be always replaced with nitrogen. As a result, it is possible to prevent the acrylic acid carried on the TAC film 11 from coming into contact with oxygen or moisture in the air, and to prevent the condensed acrylic acid from being altered. In addition, impurities such as acrylic acid vapor and air can be prevented from entering the discharge space 20a, and stable and good plasma can be generated reliably. Thereby, an adhesion promotion layer can be reliably formed on the surface of the TAC film 11. Furthermore, the acrylic acid vapor that has not been condensed can be reliably removed from the peripheral space of the TAC film 11 and can be discharged from the replacement exhaust means 82. Therefore, it is possible to prevent the acrylic acid vapor from diffusing around the device 1 and to prevent the peripheral members from being corroded.

FIG. 5 shows a modification of the method for performing the cleaning process and the bonding process after the plasma treatment process.
The PVA film 12 hangs vertically and passes between a pair of pressing rolls 72 and 72. The PVA film 12 is conveyed downward.

  The two TAC films 11, 11 that have finished the plasma treatment process extend obliquely downward from the left and right sides of the PVA film 12 so as to approach the PVA film 12, and pass between the pressing roll 72 and the PVA film 12. Has been. The surface of the TAC film 11 subjected to the plasma treatment is directed to the PVA film 12 side. A pair of pressing rolls 72, 72 sandwich the three films 11, 12, 11.

  The cleaning liquid 59A of the cleaning liquid supply source 50A contains an adhesive component. Here, for example, polyvinyl alcohol is used as the adhesive component. A polyvinyl alcohol aqueous solution is used as the cleaning liquid 59A. The polyvinyl alcohol concentration in the cleaning liquid is preferably less than 10% by mass, more preferably less than 5% by mass. The remainder of the cleaning liquid 59A excluding the adhesive component (polyvinyl alcohol) is water. Therefore, the viscosity of the cleaning liquid 59A is sufficiently small.

  A cleaning liquid supply path 51 extends from the cleaning liquid supply source 50A. The cleaning liquid supply path 51 branches into two and is inserted into the triangular spaces between the left and right TAC films 11 and the PVA film 12. A cleaning liquid nozzle 52 </ b> A is provided at the tip of each branch path of the supply path 51. The opening at the tip of the cleaning liquid nozzle 52 </ b> A is directed to the lower TAC film 11.

  A cleaning liquid 59A made of an aqueous polyvinyl alcohol solution is discharged downward from each cleaning liquid nozzle 52A and poured into the TAC film 11. As a result, the adhesion inhibitory substance of the TAC film 11 can be washed away and removed. Thereafter, the cleaning liquid 59A is spilled from the opening on the front side of the paper surface and the opening on the back side of the paper surface in FIG. 5 of the triangular space between each TAC film 11 and the PVA film 12, and is discharged.

Some cleaning liquid 59 </ b> A remains between the TAC film 11 and the PVA film 12. The TAC film 11 and the PVA film 12 are pressed against each other by a pair of pressing rolls 72, 72 with the residual cleaning liquid 59A interposed therebetween. Therefore, the TAC film 11 and the PVA film 12 can be bonded by the adhesive component in the residual cleaning liquid. The TAC film 11 can be adhered to both surfaces of the PVA film 12. Since the adhesion inhibitor is removed from the TAC film 11, sufficient adhesive strength can be obtained.
According to this embodiment, since cleaning and adhesion can be performed in the same process, the number of processes can be reduced and the processing time can be shortened.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist.
For example, the hardly adhesive resin film used for the surface treatment step is not limited to the TAC film, and films made of various resins such as COP, PP, PE, and PET can be used.

  As a polymerizable monomer used in the plasma treatment step, other hydrophilic polymerizable monomers such as methacrylic acid may be used instead of acrylic acid.

  A nozzle for blowing out the polymerizable monomer vapor-containing gas and a gas nozzle for blowing out the plasma generating gas are separated, and the nozzle for blowing out the polymerizable monomer vapor-containing gas is located downstream of the plasma generating gas blowing nozzle in the film conveying direction. Alternatively, the polymerizable monomer vapor-containing gas may be sprayed after plasma irradiation of the hardly adhesive resin film 11.

The electrode structure of the plasma processing unit is not limited to that of the embodiment, and various structures can be adopted. For example, a structure in which a plate electrode and a roll electrode are combined may be used, or a structure in which an electrode having a concave curved surface and a roll electrode are combined may be used.
The plasma processing unit according to the embodiment is a so-called direct type plasma processing apparatus that directly irradiates plasma by putting the film to be processed 11 in the discharge space 20a between the electrodes, but the present invention discharges the film 11 to be processed. The present invention can also be applied to a so-called remote plasma processing apparatus in which the plasma gas generated in the discharge space 20a is blown onto the film 11 to be processed outside the discharge space 20a without entering the space 20a.
The plasma processing unit of the embodiment is an atmospheric pressure plasma processing apparatus that performs plasma processing near atmospheric pressure, but the present invention can also be applied to a vacuum plasma processing apparatus that performs plasma processing under vacuum.

  The cleaning step is not limited to the mode shown in FIGS. 1, 2A, and 2B, and may be performed by other cleaning methods.

As the liquid removal step after washing, the hardly adhesive resin film may be heated and dried with a heater. As the heater, a radiant heater, an electric heater, a hot air heater, or the like can be used.
As the liquid removal step, a water-absorbing member such as a sponge or a non-woven fabric may be formed into a roll, for example, and brought into contact with the hardly-adhesive resin film, and the cleaning liquid may be absorbed by the water-absorbing member.
As the liquid removal step, the hardly-adhesive resin film after washing may be allowed to stand and be naturally dried.
The liquid removal step after washing may be omitted.

  A plurality of embodiments (modifications) may be combined with each other. For example, in the process gas supply system 3 of the first embodiment (FIG. 1), the gas passages 34, 35 and 36 are omitted as in the second embodiment (FIG. 3), and the downstream end of the inert gas supply passage 33 is kept at a constant temperature. A structure in which the upstream end of the process gas path 37 is directly connected to the constant temperature container 30 may be configured so as to be directly connected to the container 30. The process gas supply system 3 of the second embodiment (FIG. 3) may have a structure having gas passages 34, 35, and 36 as in the first embodiment (FIG. 1). In the process gas supply system 3 of the second embodiment (FIG. 3), similarly to the third embodiment (FIG. 4), the plasma generation gas path 34 and the polymerizable monomer vapor path 36 do not merge, and the plasma generation gas nozzle The structure may be such that 39X and the polymerizable monomer-containing gas nozzle 30Y are provided separately. When a pair of plasma generating gas nozzles 39X are arranged on both the left and right sides of the upper electrode 21, and a polymerizable monomer-containing gas nozzle 39Y is arranged on the left and right outer sides of these plasma generating gas nozzles 39X, and the film 11 moves in a relative movement direction to the right. When the gas 11 is blown out from the left nozzles 39X and 39Y and the film 11 moves in the relative direction to the left, the gas may be blown out from the right nozzles 39X and 39Y.

  You may apply the surface treatment method and surface treatment apparatus of the hardly adhesive resin film 11 for uses other than manufacture of a polarizing plate.

Examples will be described below, but the present invention is not limited to these examples.
A plasma processing step was performed using the plasma processing unit 2 and the process gas supply system 3 having the roll electrode structure shown in FIG. As the hardly adhesive resin film 11 to be treated, a TAC film (Fujitack; registered trademark) manufactured by Fuji Photo Film Co., Ltd. was used. It is thought that about 10% of triphenyl phosphate is added to this TAC film as a plasticizer. Other processing conditions are as follows.
TAC film transport speed: 8 m / min
Supply power: 1449W (210V, 6.5A DC converted to AC)
The narrowest gap between the roll electrodes 21R and 22R: 1 mm
Voltage between roll electrodes 21R and 22R: Vpp = 13.2 kV
Inert gas (plasma generating gas and carrier gas): Nitrogen gas Polymerizable monomer: Acrylic acid Temperature of liquid acrylic acid in constant temperature bath 30: 40 ° C.
Set temperature of piping 36, 37: 45 ° C
Process gas blowing temperature: 40 ° C
TAC film temperature: 25 ° C
Process gas flow rate: 50 L / min
Distribution flow rate of the plasma generation gas path 34 and the carrier path 35: The following three types (a) Plasma generation gas path 34: 40 L / min
Carrier path 35: 10 L / min
(B) Gas path 34 for plasma generation: 30 L / min
Carrier path 35: 20 L / min
(C) Gas path 34 for plasma generation: 20 L / min
Carrier path 35: 30 L / min
As the distribution flow rate to the carrier path 35 with respect to the plasma generating gas path 34 increases, the acrylic acid concentration in the process gas increases. Accordingly, the processing degree increases in the order of (a), (b), and (c).

  The TAC film plasma-treated as described above was immersed in ion-exchanged water in a water tank and moved slightly to perform a cleaning process. After washing, the TAC film was taken out from the water tank.

The TAC film was cut into a 25 mm wide strip to obtain a plurality of TAC film sample pieces. The TAC film sample pieces were collected from one end side and the other end side in the width direction of the TAC film. And the TAC film sample piece was adhere | attached on both surfaces of the sample piece of the PVA film, and the polarizing plate sample of the same cross-sectional structure as the polarizing plate 10 shown to Fig.6 (a) was produced. As the adhesive, a polyvinyl alcohol-based aqueous adhesive containing the following components was used.
20% aqueous solution of Kuraray Kuraray Poval PVA217 dissolved in water: 95.0 wt% or more Methanol: less than 5.0 wt% Methyl acetate: less than 1.0 wt%

  After the adhesive was cured through a drying process at 80 ° C. for 5 minutes, the adhesive strength (material breaking strength) of the polarizing plate sample piece was measured by the floating roller method (JIS K6854).

  As Comparative Example 1, a polarizing plate sample was prepared by the same method as in Example 1 except that the cleaning step was omitted, and the adhesive strength was measured by the same method as in Example 1.

表１において、処理条件（ａ）、（ｂ）、（ｃ）は、上記キャリア路３５とプラズマ生成用ガス路３４の分配流量を示し、処理度に対応する。上述したように、処理度は、（ａ）、（ｂ）、（ｃ）の順に高くなる。各処理条件（ａ）〜（ｃ）において接着強度データが２つあるのは、ＴＡＣフィルムの幅方向の一端側から採取した試料片と幅方向の他端側から採取した試料片についてそれぞれ接着強度を測定したことによる。 The results are shown in Table 1.

In Table 1, the processing conditions (a), (b), and (c) indicate the distribution flow rates of the carrier path 35 and the plasma generation gas path 34 and correspond to the processing degree. As described above, the processing degree increases in the order of (a), (b), and (c). In each treatment condition (a) to (c), there are two adhesion strength data for the sample piece taken from one end side in the width direction of the TAC film and the sample piece taken from the other end side in the width direction. By measuring.

  As is apparent from Table 1, when the plasma treatment was not performed (Comparative Example 1), the adhesive strength was significantly reduced when the treatment degree was increased. This is presumably because the amount of adhesion-inhibiting substances generated increases as the treatment degree increases. On the other hand, when the cleaning was performed after the plasma treatment (Example 1), substantially the same adhesive strength could be maintained even when the treatment degree was increased. This is probably because the adhesion-inhibiting substance was removed by washing. Therefore, even if the processing conditions in the plasma processing step are not set severely, it was confirmed that good adhesive strength can be obtained and the productivity can be stabilized by executing the cleaning step thereafter.

  In addition, the initial contact angle (to water) of the TAC film 11 before the plasma treatment was 60 °. The contact angle of the TAC film 11 after the plasma treatment was 10 ° in any of the treatment conditions (a) to (c) of Example 1 and Comparative Example 1, and the hydrophilicity was increased. In Example 1, the contact angle of the TAC film 11 after the cleaning step was 60 ° under any of the processing conditions (a) to (c), and the hydrophilicity was lowered. This indicates that there is no strong correlation between hydrophilicity and adhesiveness.

A plasma processing step was performed on the same type of TAC film as in Example 1 using the plasma processing unit 2 and the process gas supply system 3 having a parallel plate electrode structure shown in FIG. The processing conditions are as follows.
Supply power: 429W (110V, 3.9A DC converted to AC)
Gap between plate electrodes 21 and 22: 1 mm
Voltage between flat plate electrodes 21 and 22: Vpp = 12 kV
Inert gas (plasma generating gas and carrier gas): nitrogen gas Polymerizable monomer: acrylic acid Process gas flow rate: 10 L / min
Temperature of liquid acrylic acid in the thermostat 30: 50 ° C
The temperature of the pipes 36 and 37: 50 ° C
Process gas blowing temperature: 37 ° C
TAC film temperature: 25 ° C
Number of scans of stage 22: 2 Stage 22 transport speed: 3 types as follows (d) 10 m / min
(E) 5m / min
(F) 1 m / min
The slower the conveyance speed of the stage 22, the more time the TAC film is exposed to plasma. Accordingly, the processing degree increases in the order of (d), (e), and (f). One scan means that the stage 22 is moved only once from left to right or from right to left. Therefore, the number of scans of 2 means that the stage 22 is reciprocated once.

  The TAC film plasma-treated as described above was immersed in ion-exchanged water in a water tank and moved slightly to perform a cleaning process. After washing, the TAC film was taken out from the water tank.

  The TAC film was cut into a 25 mm wide strip to obtain a plurality of TAC film sample pieces. And the TAC film sample piece was adhere | attached on both surfaces of the sample piece of the PVA film using the same adhesive agent as Example 1, and the polarizing plate sample of the same cross-sectional structure as the polarizing plate 10 shown to Fig.6 (a) was produced. . Five polarizing plate samples were prepared for each of the three conditions (d) to (f). The adhesive strength (material breaking strength) of the polarizing plate sample was measured by the floating roller method (JIS K6854).

  As Comparative Example 2, a polarizing plate sample was prepared by the same method as in Example 2 except that the cleaning step was omitted, and the adhesive strength was measured by the same method as in Example 2.

The results are shown in Table 2. In addition, each measured value of the table takes the average of the measurement result of five polarizing plate samples.

  As can be seen from Table 2, in the case of no cleaning in Comparative Example 2, the adhesive strength significantly decreased as the treatment degree increased. It is presumed that the amount of adhesion-inhibiting substance generated increases as the treatment degree increases. On the other hand, in the case where the cleaning process of Example 2 was performed, the adhesive strength did not decrease even when the degree of treatment increased, but rather the adhesive strength increased. This is presumably because the adhesion promoting layer was reliably formed as the degree of treatment increased, and the adhesion inhibiting substance could be removed by washing. Therefore, even if the processing conditions in the plasma processing step are not set severely, it was confirmed that good adhesive strength can be obtained and the productivity can be stabilized by executing the cleaning step thereafter.

1 is a front view schematically showing a surface treatment apparatus according to a first embodiment of the present invention. It is a front view which shows the modification of a washing | cleaning part. It is a front view which shows the other modification of a washing | cleaning part. It is a front view which shows roughly the surface treatment apparatus of 2nd Embodiment which concerns on the modification of a plasma processing part and a process gas supply system. It is a front view which shows roughly the surface treatment apparatus of 3rd Embodiment which concerns on the modification of a plasma processing part and a process gas supply system. It is an explanatory front view showing an embodiment performed in parallel with a cleaning process and an adhesion process. (A) is sectional drawing of a polarizing plate, (b) is sectional drawing of a polarizing plate with a hard cord layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma surface treatment apparatus 10 Polarizing plate 11 TAC film (hardly adhesive resin film)
12 PVA film (adhesive resin film)
DESCRIPTION OF SYMBOLS 13 Adhesive 14 Hard-coat layer 2 Plasma processing part 20a Discharge space 21, 22 Flat plate electrode 21R, 22R Roll electrode 26 Moving mechanism 27 Folding roll 28 Film temperature control means 3 Process gas supply system 30 Constant temperature container (polymerizable monomer supply source)
31 inert gas supply source 32 heater 33 inert gas supply path 34 plasma generation gas path 34v flow rate adjusting means 35 carrier path 35v flow rate adjusting means 36 polymerizable monomer vapor path 37 process gas path 38 gas temperature adjusting means 39 process gas nozzle 39X Plasma generation gas nozzle 39Y Polymerizable monomer-containing gas nozzle 40 Exhaust means 41 Suction passage 42 Suction nozzle 5 Cleaning section 50 Cleaning liquid supply source 51 Cleaning liquid supply passage 52 Cleaning liquid spray nozzle 52A Adhesive component-containing cleaning liquid nozzle 53 Cleaning liquid container 54 Sponge roll 55 Transfer Roll 56 Cleaning liquid supply nozzle 59 Ion exchange water (cleaning liquid)
59A Polyvinyl alcohol aqueous solution (adhesive component-containing cleaning solution)
6 Liquid Removal Unit 60 Liquid Removal Gas Supply Source 61 Liquid Removal Gas Supply Path 62 Liquid Removal Nozzle 72 Pushing Roll 8 Chamber 80 Replacement Gas Supply Source 81 Replacement Gas Supply Path 82 Replacement Exhaust Means 83 Replacement Suction Path

Claims (9)

A method for treating a surface of a difficult-to-adhere resin film to be adhered to an easily-adhesive resin film,
A plasma treatment step in which a polymerizable monomer is activated by plasma to react with the hardly adhesive resin film;
A film surface treatment method comprising: a washing step of washing the hardly adhesive resin film with a washing liquid after the plasma treatment step.   The film surface treatment method according to claim 1, wherein the polymerizable monomer is acrylic acid or methacrylic acid.   3. The film surface treatment method according to claim 1, wherein the cleaning liquid is an aqueous cleaning liquid containing 90% by mass or more of water.   The film surface treatment method according to claim 1, wherein the cleaning liquid is pure water or ion-exchanged water.   A bonding step of bonding the hardly adhesive resin film treated by the film surface treatment method according to any one of claims 1 to 4 and the easily adhesive resin film with an adhesive is provided. Film adhesion method.   The cleaning liquid contains an adhesive component, and the hardly adhesive resin film and the easily adhesive resin film are bonded together with the cleaning process in parallel with the cleaning liquid used in the cleaning process. The film bonding method according to claim 5.   The method for adhering a film according to claim 6, wherein the cleaning liquid is an aqueous polyvinyl alcohol solution containing less than 10% by mass of polyvinyl alcohol as the adhesive component.   The method for adhering a film according to claim 6, wherein the cleaning liquid is an aqueous polyvinyl alcohol solution containing less than 5 mass% of polyvinyl alcohol as the adhesive component.   It is a manufacturing method of the polarizing plate using the film adhesion method of any one of Claims 5-8, Comprising: The said hardly adhesive resin film is a protective film which has a triacetate cellulose as a main component, The said easy A method for producing a polarizing plate, wherein the adhesive resin film is a polarizing film containing polyvinyl alcohol as a main component.

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