JPWO2009008284A1 - Film surface treatment method, polarizing plate production method, and surface treatment apparatus - Google Patents

Abstract

The adhesion of a triacetate cellulose film to a polyvinyl alcohol film is ensured regardless of saponification treatment. Prior to bonding a second film 12 containing triacetate cellulose as a main component to a first film 11 made of a polyvinyl alcohol-based resin, a reactive gas is converted into plasma, and the first film 11 of the second film 12 Touch the adhesive surface. The reaction gas includes acrylic acid or methacrylic acid. [Selection] Figure 2

Description

  In the present invention, a PVA film (first film) made of a polyvinyl alcohol (hereinafter referred to as “PVA” if necessary) resin is mainly composed of triacetate cellulose (hereinafter referred to as “TAC” if necessary). Prior to adhering the TAC film (second film) included as a surface treatment method applied to the TAC film to enhance adhesion, and the PVA film as a polarizing film, a TAC film was laminated as a protective film on the polarizing film The present invention relates to a method of manufacturing a polarizing plate. In particular, the present invention relates to a method in which a TAC film is surface-treated without using a saponification treatment and bonded to a PVA film.

For example, a polarizing plate is incorporated in the liquid crystal display unit. The polarizing plate is obtained by bonding a protective film made of a TAC film to a polarizing film made of PVA resin with an adhesive. Prior to bonding, the TAC film is immersed in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide and saponified. The reason for the saponification treatment is to increase the hydrophilicity of the TAC film and ensure the adhesion of the TAC film to the polarizing film. As an adhesive, a polyvinyl alcohol-based or polyether-based adhesive is generally used.
In Patent Document 1, after a TAC film is saponified, a hard coat layer is laminated on the TAC film by coating, and then the TAC film with a hard coat layer is attached to both sides of a uniaxially stretched polarizing film with polyvinyl alcohol. Laminated using a system adhesive.
In Patent Document 2, the reaction gas is converted into plasma under atmospheric pressure. The base film is made hydrophobic by using acrylic acid or methacrylic acid as a reaction gas component.
In Patent Document 3, one surface of a saponified TAC film is surface-treated by low-pressure glow discharge or the like, and a hard coat layer is laminated on the surface-treated surface of the TAC film by coating. The surface treatment improves the adhesion between the hard coat layer and the TAC film.
In Patent Document 4, a substrate such as a TAC film is surface-treated with plasma near atmospheric pressure. As the surface treatment gas, a mixed gas of a discharge gas such as nitrogen or argon and a thin film forming gas is used. By using acrylic acid, methacrylic acid or the like as the gas for forming a thin film, the hydrophilicity of the substrate is enhanced. This improves the adhesion between the base material and a film such as an antireflection film formed by plasma treatment on the base material.
Japanese Patent Laid-Open No. 08-171016 JP 2003-151568 (paragraphs 0001, 0047) JP 2003-227932 A JP 2006-299000 A (paragraphs 0113 to 0119, 0130, 0143)

The TAC film subjected to saponification treatment was liable to have low heat resistance or partial blocking during storage in a roll state. Further, when a hard coat is applied to the surface opposite to the adhesive surface of the TAC film, there is a problem that the haze value is increased by the saponification treatment and the optical characteristics are changed. There was also a problem of waste liquid treatment of alkaline aqueous solution used for saponification treatment.
On the other hand, in the case of an unsaponified TAC film, conventional polyvinyl alcohol-based or polyether-based adhesives could not be bonded to the polarizing film. Even an olefin-based water-based adhesive such as a polyolefin-based polyol (Japanese Patent Laid-Open No. 2003-155379) could not be bonded.

The inventor has intensively studied to solve the above problems. As a result, it was found that the same adhesiveness as that obtained by saponification treatment can be obtained when a monomer of a certain organic compound is converted into plasma and irradiated on the TAC film.
The present invention has been made based on the above findings, and prior to bonding a second film containing triacetate cellulose (TAC) as a main component to a first film made of a polyvinyl alcohol (PVA) resin, A surface treatment method applied to the second film, the surface of the second film to be bonded to the first film after being plasmatized (including decomposition, excitation, activation, radicalization, and ionization) It is a thing made to contact.
In the present invention, a first film made of PVA resin is laminated with a second film containing TAC as a main component, the first film becomes a polarizing film, and the second film becomes a protective film. A method of manufacturing a plate, comprising: a surface treatment step of converting a reactive gas into plasma to contact a surface of the second film to be bonded to the first film; and thereafter bonding the first film and the second film And an adhesion step of adhering with an agent.
The reaction gas contains a monomer having an unsaturated bond and a predetermined functional group as a reaction component. The predetermined functional group is 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, and a carboxyl group is particularly preferable.

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 reaction gas includes 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 monomer may be converted into plasma by being carriered by an inert gas. The inert gas is selected from nitrogen, argon, helium, etc., and nitrogen is preferably used from the viewpoint of economy.
Many of the above listed monomers including acrylic acid and methacrylic acid are in a liquid phase at normal temperature and pressure. Such a monomer is preferably vaporized in an inert gas to obtain a mixed gas of the vaporized monomer and the inert gas, and this mixed gas is used as the reaction gas. Monomers such as acrylic acid and methacrylic acid are preferably vaporized by heating, bubbling, or the like, and then carriered in the inert gas.
Considering the burden on the heater when heated and vaporized, it is preferable to select a monomer having a boiling point of 300 ° C. or less. Moreover, it is preferable to select a monomer that does not decompose (chemically change) by heating.

  When a functional layer such as a hard coat layer or an AR (Anti-Reflection) layer is coated on the surface of the second film opposite to the surface to be bonded to the first film, The reactive gas is introduced between the second film and the other electrode with the functional layer facing the discharge surface of one of the electrodes and the discharge surface covered with the second film without a gap. It is preferable to do. As a result, it is possible not only to reliably bring the reactive gas that has been made into plasma into contact with the adhesive surface of the second film with the polarizing film, but also to form plasma between the functional layer and the one electrode, It is possible to prevent the converted reaction gas from entering, and to prevent the functional layer from being damaged.

  The adhesive that bonds the second film and the first film subjected to the surface treatment of the present invention is not particularly limited, and a polyvinyl alcohol-based adhesive liquid mainly composed of a polyvinyl alcohol aqueous solution, a polyvinyl butyral solution, Examples include vinyl polymerization latexes mainly composed of butyl acrylate, olefin aqueous adhesives based on polyolefin polyols, polyether adhesives, etc., but polyvinyl alcohols based on polyvinyl alcohol aqueous solutions. It is more preferable to use an adhesive.

The reaction gas is preferably converted to plasma under a pressure close to 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 reaction gas preferably contains acrylic acid or methacrylic acid, and particularly preferably contains acrylic acid.

  In the surface treatment method or the surface treatment step of the polarizing plate production method, the temperature of the portion of the second film that contacts the reaction gas (hereinafter referred to as “film temperature”) is the second of the reaction gas. It is preferable that the temperature is lower than the jetting temperature to the film (hereinafter referred to as “gas jetting temperature”), and the difference between the gas jetting temperature and the film temperature is 5 ° C. or more, and the temperature difference is 10 ° C. or more. Is more preferable.

  The film temperature is preferably room temperature or higher. Here, the room temperature is generally 20 to 25 ° C., and more generally 25 ° C. It is preferable that the reaction gas has a temperature lower than the flash point of acrylic acid or methacrylic acid and higher than the second film by 5 ° C. or more. More preferably, the reaction gas is lower than the flash point of acrylic acid or methacrylic acid and higher than the second film by 10 ° C. or higher. The flash point of acrylic acid is 54 ° C. The flash point of methacrylic acid is 77 ° C. Incidentally, the ignition point of acrylic acid is 360 ° C. The ignition point of methacrylic acid is 360 ° C.

  The oxygen content of the reaction gas is preferably 0 to 3000 ppm, and more preferably 2000 ppm or less.

The surface treatment apparatus according to the present invention is used in the surface treatment method or used in the surface treatment step of the polarizing plate production method,
A plasma processing unit having a processing space in which the second film is disposed, and performing the plasma in or near the processing space;
A reaction gas supply system for supplying a reaction gas to the processing space;
Film temperature adjusting means for adjusting the temperature of the portion of the second film that contacts the reactive gas (hereinafter referred to as “film temperature”);
A gas temperature adjusting means for adjusting an ejection temperature of the reaction gas to the second film (hereinafter referred to as “gas ejection temperature”);
It has. Preferably, the film temperature adjusting means and the gas temperature adjusting means adjust the film temperature to be lower than the gas ejection temperature. More preferably, the difference between the gas ejection temperature and the film temperature is adjusted to 5 ° C. or more, more preferably 10 ° C. or more by the film temperature adjusting means and the gas temperature adjusting means.

  According to the present invention, the adhesiveness of the TAC film to the PVA film can be ensured regardless of the saponification treatment.

(A) shows sectional drawing of a polarizing plate, (b) shows sectional drawing of a polarizing plate with a hard cord layer. It is a schematic block diagram which shows an example of the atmospheric pressure plasma processing apparatus used for the surface treatment of a TAC film. It is a graph which shows the relationship (theoretical value) with the limit concentration of acrylic acid which can be contained in a nitrogen carrier, and temperature. It is a schematic block diagram which shows 2nd Embodiment of this invention and shows the modification of an atmospheric pressure plasma processing apparatus. It is a schematic block diagram of the atmospheric pressure plasma processing apparatus which concerns on 3rd Embodiment of this invention. It is a graph which shows the measurement result of the contact angle (hydrophilicity) in Example 4. It is a schematic block diagram of the atmospheric pressure plasma processing apparatus used for Example 5. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = + 17 degreeC. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = + 12 degreeC. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = + 10 degreeC. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = + 7 degreeC. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = + 7 degreeC. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = + 5 degreeC. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = + 2 degreeC. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = + 2 degreeC. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = + 2 degreeC. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = -3 degreeC. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = -3 degreeC. In Example 5, it is a graph which shows adhesiveness when the difference of gas ejection temperature and film temperature is (DELTA) T = -8 degreeC. It is a schematic block diagram of the atmospheric pressure plasma processing apparatus used for Example 6. It is a schematic block diagram of the atmospheric pressure plasma processing apparatus used for Example 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface treatment apparatus 2 Plasma processing part 3 Reactive gas supply system 10 Polarizing plate 11 Polarizing film (PVA film, 1st film)
12 Protective film (TAC film, second film)
DESCRIPTION OF SYMBOLS 13 Adhesive 14 Hard-coat layer 21,21R Power supply side electrode 22,22R Ground side electrode 23 Power supply 27 Film temperature control means 29 Processing space 30 Reaction component supply source (container)
33 Heater (vaporization means)
34 Carrier supply source 36 Heat insulating material 39 Gas temperature adjusting means Ac Acrylic acid (reactive gas component)
p Atmospheric pressure plasma space

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1A shows a polarizing plate 10 for a liquid crystal display. The polarizing plate 10 includes a polarizing film 11 and a pair of protective films 12 stacked on both surfaces of the polarizing film 11. The polarizing film 11 is made of a polyvinyl alcohol (PVA) resin. Hereinafter, the polarizing film 11 is also referred to as a PVA film 11 or a first film 11 as necessary.

  The protective film 12 contains triacetate cellulose (TAC) as a main component. Hereinafter, the protective film 12 is also referred to as a TAC film 12 or a second film 12 as necessary. The TAC film 12 contains 90% or more of triacetate cellulose. The TAC film 12 may contain about 3 to 10% by weight of a plasticizer such as a phosphate ester in addition to triacetate cellulose, and may contain an ultraviolet absorber. The thickness of the TAC film is not particularly limited and is, for example, several μm to several hundred μm. As the TAC film 12, an unsaponified film that has not been saponified is used. The manufacturing method of the TAC film 12 is not particularly limited, and for example, it is manufactured by a casting method.

  The PVA film 11 and the TAC film 12 are bonded with an adhesive 13. As the adhesive 13, a polyvinyl alcohol-based adhesive whose main component is an aqueous polyvinyl alcohol solution is used, but the present invention is not limited to this, and a polyvinyl alcohol-based adhesive whose main component is an aqueous polyvinyl butyral solution or the like is used. It is also possible to use a vinyl polymer latex based on butyl acrylate or the like, a polyether adhesive, or an aqueous olefin adhesive based on a polyolefin polyol or the like. Also good.

  As shown in FIG.1 (b), the hard-coat layer 14 may be laminated | stacked as a functional layer on the front side surface (surface on the opposite side to the adhesive surface with the PVA film 11) of one TAC film 12. FIG. Instead of the hard coat layer 14, an AR layer and other functional layers may be laminated.

Prior to adhesion with the PVA film 11, the TAC film 12 is subjected to a surface treatment process for ensuring adhesion.
As shown in FIG. 2, the surface treatment apparatus 1 is used for the surface treatment process. The surface treatment apparatus 1 is composed of an atmospheric pressure plasma treatment apparatus. The apparatus 1 includes a plasma processing unit 2 and a reactive gas supply system 3. The plasma processing unit 2 includes a flat electrode 21 and a roll electrode 22R. A processing space 29 is formed between the electrodes 21 and 22R.

  A power source 23 is connected to the plate electrode 21, and the roll electrode 22R is electrically grounded. The power source 23 applies, for example, a pulsed voltage to the plate electrode 21. As a result, a pulsed electric field is formed between the plate electrode 21 and the roll electrode 22 </ b> R, and atmospheric pressure plasma p is generated in the processing space 29. The pulse rise and / or fall time 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 supply voltage is not limited to a pulse shape, and may be a continuous wave shape such as a sine wave.

The TAC film 12 is partially wound around the upper peripheral surface of the roll electrode 22R (the discharge surface of one electrode) and covers the upper peripheral surface of the roll electrode 22R. A portion of the TAC film 12 that covers the electrode 22 </ b> R is disposed in the processing space 29. One side of the TAC film 12 (adhesive surface to be bonded to the PVA film 11) faces the upper flat plate electrode 21, and the opposite surface is in contact with the upper peripheral surface of the roll electrode 22R without a gap. In the case of the TAC film 12 with the hard coat layer 14 shown in FIG. 1B, the hard coat layer 14 comes into contact with the upper peripheral surface of the roll electrode 22R without any gap.
The TAC film 12 is transported in one direction by the rotation of the roll electrode 22R and the transport roll 24.

The reaction gas supply system 3 includes a reaction component supply source 30 and a carrier supply source 34. The reaction component supply source 30 is composed of a container that stores reaction components. The reaction component is a monomer having an unsaturated bond and a predetermined functional group. Here, acrylic acid (CH ₂ ═CHCOOH) is used as the reaction component. Acrylic acid is a monomer having an ethylenically unsaturated double bond and a carboxyl group. Acrylic acid is stored in the container 30 in a liquid phase. In the figure, liquid acrylic acid is indicated by “Ac”. A heater 33 is incorporated in the container 30 as a vaporizing means. The container 30 constitutes a thermostatic bath. The liquid acrylic acid Ac is heated by the heater 33 and vaporized. The heating temperature of acrylic acid Ac is preferably from room temperature (25 ° C.) to 80 ° C., and from the viewpoint of safety, it is preferable to set it to 50 ° C. or less in view of the flash point being 54 ° C. As shown in FIG. 3, the vaporization amount of acrylic acid can be adjusted by the heating temperature of the liquid acrylic acid Ac.
If the vaporization amount of acrylic acid satisfies the required amount even near the room temperature, the heater 33 may be omitted.

  The carrier supply source 34 stores nitrogen as a carrier gas. Instead of nitrogen as a carrier gas, other inert gases such as argon and helium may be used. A carrier path 35 extends from the carrier supply source 34. A carrier path 35 is connected to the reaction component container 30.

Nitrogen from the carrier supply source 34 is introduced into the reaction component container 30 from the carrier path 35. Inside the reaction component container 30, nitrogen gas and vaporized acrylic acid gas (reaction component) are mixed. Thereby, the reaction gas which consists of a mixed gas of acrylic acid and nitrogen is produced | generated. As described above, the concentration of acrylic acid in the reaction gas (acrylic acid + nitrogen) can be adjusted by the heating temperature of the liquid acrylic acid Ac by the heater 33.
The end of the carrier path 35 is located above the liquid surface of the acrylic acid Ac, but it may be extended to the inside of the liquid of the acrylic acid Ac and bubbled.

  A supply path 31 extends from the reaction component container 30 to the plasma processing unit 2. A jet nozzle 32 is provided at the tip of the supply path 31. The ejection nozzle 32 is provided on one side of the plate electrode 21.

  The reaction gas (acrylic acid + nitrogen) generated in the reaction component container 30 is blown out from the discharge nozzle 32 to the processing space 29 via the supply path 31. Plasma p is generated in the processing space 29, and the reaction gas is turned into plasma (including decomposition, excitation, activation, and ionization). This plasma-ized gas comes into contact with one side of the TAC film 12 (adhesive surface with the PVA film 11), and plasma surface treatment is performed.

  The TAC film 12 covers the upper peripheral surface of the roll electrode 22R without a gap. Therefore, plasma can be prevented from being formed between the roll electrode 22R and the TAC film 12. Further, it is possible to prevent the reaction gas that has been converted into plasma between the TAC film 12 and the flat plate electrode 21 from entering between the roll electrode 22 </ b> R and the TAC film 12. Therefore, in the case of the TAC film 12 with the hard coat layer 14 shown in FIG. 1B, the hard coat layer 14 can be prevented from being deteriorated by being exposed to plasma, and optical characteristics such as haze value can be prevented from deteriorating. can do.

A suction nozzle 42 is provided on the opposite side of the electrode 21 from the ejection nozzle 32 side. The suction nozzle 42 is connected to the exhaust means 40 via the suction path 41.
The gas that has been processed in the processing space 29 is sucked from the suction nozzle 42 and is exhausted by the exhaust means 40 through the suction path 41.

[Adhesion process]
After the surface treatment step, the adhesive surface of the TAC film 12 and the PVA film 11 are adhered with an adhesive 13. Since the adhesive surface of the TAC film 12 is subjected to the above-described plasma surface treatment, good adhesiveness can be obtained, and the TAC film 12 can be firmly bonded to the PVA film 11.

Next, another embodiment of the present invention will be described. In the following embodiments, the same components as those described above are denoted by the same reference numerals and description thereof will be omitted (the same applies to the examples described later).
FIG. 4 shows a second embodiment. In the second embodiment, the electrode structure of the atmospheric pressure plasma processing apparatus 1 is composed of a pair of roll electrodes 21R and 22R. The pair of roll electrodes 21R and 22R face each other in the vertical direction. A power source 23 is connected to the upper roll electrode 21R. The lower roll electrode 22R is electrically grounded. With such an electrode structure, an atmospheric pressure plasma discharge p is generated between the roll electrodes 21R and 22R.
The TAC film 12 is passed between these roll electrodes 21R and 22R in a state of being stretched straight, but may be wound around one roll electrode 22R as in the embodiment of FIG.

  FIG. 5 shows a third embodiment. In the third embodiment, a pair of roll electrodes 21R and 22R are arranged to face the left and right. An atmospheric pressure plasma p is generated in a processing space 29 formed between the roll electrodes 21R and 22R. An ejection nozzle 32 is provided above the processing space 29. A pair of left and right folding rollers 25 and 26 are provided below the roll electrodes 21R and 22R.

  The TAC film 12 is wound in the order of the roll electrode 21R, the folding roller 25, the folding roller 26, and the roll electrode 22R. The TAC film 12 is surface-treated while passing through the treatment space 29 while being wound around the roll electrode 21R. Thereafter, the TAC film 12 is unwound from the roll electrode 21R, folded back by the folding rollers 25 and 26, and wound around the ground-side roll electrode 22R. At this time, the TAC film 12 passes through the treatment space 29 again and is surface-treated. Therefore, the TAC film 12 is processed twice in one processing space 29.

  A film temperature adjusting means 27 is incorporated in the power supply side roll electrode 21R. The film temperature adjusting means 27 is configured by a temperature adjustment path for circulating a temperature adjustment medium having a predetermined temperature inside the roll electrode 21R. For example, water is used as the temperature control medium. Thereby, the temperature of the roll electrode 21R can be adjusted. Therefore, the temperature of the film 12 where the TAC film 12 is in contact with the roll electrode 21R, and the part where the reactive gas is sprayed (hereinafter referred to as “film temperature Tb”) can be adjusted. The film temperature Tb is preferably about dew point to about 80 ° C. By setting the film temperature Tb to the dew point or higher, it is possible to prevent the TAC film 12 from being condensed. By setting the film temperature Tb to 80 ° C. or less, it is possible to prevent the TAC film 12 from undergoing thermal deformation.

  Similarly, the temperature adjusting means 27 is also incorporated in the ground side roll electrode 22R. Thereby, the temperature of the roll electrode 22R can be adjusted. As a result, the temperature Tb of the part which contacts the reactive gas of the TAC film 12 can be adjusted.

  Further, a heat insulating material 36 is provided on the outer periphery of the pipe constituting the reaction gas supply path 31. When the reaction gas (acrylic acid + nitrogen) passes through the supply path 31, it is kept warm by the heat insulating material 36 and is ejected from the ejection nozzle 32 in a state where the temperature in the reaction component container 30 is substantially maintained. The reaction component container (constant temperature bath) 30 including the heater 33 and the heat insulating material 36 constitute a gas temperature adjusting means 39. The gas temperature adjusting means 39 adjusts the temperature of the reaction gas, particularly the temperature at which the reactant gas is ejected from the ejection nozzle 32 (hereinafter referred to as “gas ejection temperature Ta”). The gas ejection temperature Ta is preferably about 35 ° C to 80 ° C. The gas ejection temperature Ta is more preferably 40 ° C to 50 ° C.

  Further, the film temperature Tb (≧ room temperature) is adjusted to be lower than the gas ejection temperature Ta by the two temperature adjusting means 27 and 39. Preferably, the temperature difference ΔT = Ta−Tb is adjusted so that ΔT ≧ + 5 ° C. More preferably, it is adjusted so that ΔT ≧ + 10 ° C.

  The upper limit of ΔT is preferably set in a range where the TAC film 12 does not undergo thermal deformation such as swelling. The limit temperature at which the TAC film 12 does not undergo thermal deformation such as swelling is, for example, about 80 ° C., although it depends on the processing conditions. When the humidity is controlled to be kept low, a practical lower limit room temperature is, for example, about 10 ° C. at a temperature at which no condensation occurs. Therefore, from the viewpoint of preventing thermal deformation of the TAC film 12 and preventing condensation, about ΔT ≦ + 70 ° C. is preferable. Further, from the viewpoint of safety considering the flash point (54 ° C.) of acrylic acid and from the viewpoint of more reliably preventing condensation, ΔT ≦ + 30 ° C. is preferable. Even more preferably, ΔT ≦ + 20 ° C.

  By performing the surface treatment of the TAC film 12 under the condition of the temperature difference ΔT, the adhesiveness between the TAC film 12 and the PVA film 11 can be sufficiently enhanced.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, methacrylic acid may be used as a reaction component in the reaction gas instead of acrylic acid.
You may apply the said surface treatment method of the TAC film 12 for uses other than manufacture of a polarizing plate.
The end of the carrier path 35 is located above the liquid surface of the acrylic acid Ac, but it may be extended to the inside of the liquid of the acrylic acid Ac and bubbled.

  The electrode structure of the plasma processing apparatus 1 is not limited to that shown in the embodiment, and may be a parallel plate electrode. Instead of the plate electrode 21, an electrode whose discharge surface is a concave surface along the curved surface of the roll electrode 22R may be used, or a roll electrode or a rod-like electrode having a smaller diameter than the roll electrode 22R may be used.

  In the above embodiment, the TAC film 12 is passed through the space (gap) between the electrodes of the plasma processing unit 2, and the interelectrode space is the processing space 29 in which the TAC film 12 is surface-treated. However, the reaction gas may be blown out toward the TAC film in the processing space after being converted into plasma in the interelectrode space. In this case, the temperature of the reaction gas at the time of being ejected from the inter-electrode space into the processing space after the plasma is preferably 5 ° C. or higher, more preferably 10 ° C. or higher than the film temperature Tb.

  Plasma generation is not limited to the vicinity of atmospheric pressure, and may be performed under vacuum.

  The first to third embodiments may be combined with each other. For example, in the first and second embodiments (FIGS. 2 and 4), as in the third embodiment, the film temperature adjusting means 27 and the gas temperature adjusting means 39 are incorporated so that the gas ejection temperature Ta is higher than the film temperature Tb. The temperature difference may be adjusted to be high, and preferably the temperature difference ΔT = Ta−Tb may be adjusted to satisfy ΔT ≧ + 5 ° C., more preferably ΔT ≧ + 10 ° C. The upper limit of ΔT may be set within a range in which the TAC film 12 does not undergo thermal deformation such as swelling.

  The film temperature adjusting means 27 may be an electric heater, a hot wire heater, or a warm air heater. The heater may be built in the electrode or may be disposed outside the electrode.

  As the gas temperature adjusting means 39, an electric heater such as a ribbon heater or a hot wire heater may be provided on the outer periphery of the pipe constituting the reaction gas supply path 31. The gas temperature adjusting means 39 may be a heat exchanger. For example, as the gas temperature adjusting means 39, a heat exchange pipe for circulating a temperature control medium such as water may be provided so as to be able to exchange heat with a pipe constituting the reaction gas supply path 31. The gas temperature adjusting means 39 may be a hot air heater.

Examples will be described, but the present invention is not limited to this embodiment.
Plasma surface treatment of the TAC film was performed using the atmospheric pressure plasma treatment apparatus 1 shown in FIG. As the TAC film, Fujitac (registered trademark) manufactured by Fuji Photo Film Co., Ltd. was used. Its thickness was 30 μm.
The processing conditions are as follows.
Output pulse frequency from power supply 23: 5 to 30 kHz
Pulse voltage between electrodes 21 and 23: Vpp = 13 to 18 kV
Flow rate of reaction gas (acrylic acid + nitrogen): 10 L / min
Acrylic acid concentration in reaction gas: 0.1-10 vol%
TAC film transport speed: 2 m / min

An adhesive was applied to one side of the TAC film after the plasma surface treatment. As the adhesive, an aqueous adhesive in which the following components were mixed was used. The following components are mixed to make 100%.
20% aqueous solution of Kuraray Co., Ltd. Kuraray Poval PVA217 dissolved in water: 95.0 wt% or more Methanol: less than 5.0 wt% Methyl acetate: less than 1.0 wt% TAC films coated with adhesive on both sides of the polarizing film, respectively Lamination was performed using a nip roll while applying pressure. The temperature was from room temperature to 80 ° C., and the pressure was 1 to 10 kg / cm ² . The polarizing film was made of PVA resin and had a thickness of 12 μm. The obtained polarizing plate was heat-dried in a reaction component container at 80 ° C. for 5 minutes and then allowed to stand at room temperature for 12 hours.

The following evaluation was performed about this polarizing plate.
Adhesive strength evaluation In accordance with JIS K6854, the polarizing plate was cut to a width of 25 mm to form a strip, and a T-type peel test was performed under conditions of room temperature (23 ° C.) and tensile strength of 100 mm / min.
As a result, it was confirmed that the polarizing plate broke and had a sufficiently large adhesive force.
Moisture and heat resistance evaluation The polarizing plate was cut into a size of 50 mm x 50 mm and immersed in warm water at 70 ° C.
Even if 120 minutes passed in this immersion state, the TAC film was not peeled off from the polarizing film, and the polarizing film was not discolored. Thereby, it was confirmed that heat-and-moisture resistance is also favorable.

[Comparative Example 1]
As a comparative example, a polarizing plate was prepared using a conventional TAC film that had been saponified. As an alkaline solution for saponification, a 2N sodium hydroxide aqueous solution heated to 40 to 60 ° C. was used, and a TAC film was immersed in the solution for 30 to 150 seconds. Then, it wash | cleaned with normal temperature water and neutralized with 1-5 wt% HCl. Furthermore, it was made to dry at about 80 degreeC after water washing. The saponified TAC film and PVA polarizing film thus obtained were bonded under the same conditions as in Example 1 to obtain a polarizing plate. This polarizing plate was immersed in warm water at 70 ° C. And when the state after 120 minutes passed was observed, the polarizing film was discolored.
Thereby, it was confirmed that the polarizing plate by the process of this invention has higher moisture resistance than the conventional polarizing plate which saponified.

  As a reaction gas component, methacrylic acid which is the same carboxyl group was used instead of acrylic acid. The other processing conditions and adhesion conditions were the same as in Example 1 to produce a polarizing plate, and the same adhesive strength evaluation as in Example 1 was performed. As a result, the polarizing plate broke. (The degree of material breakage was low as compared with Example 1.) Thus, it was confirmed that sufficient adhesive strength could be obtained even with methacrylic acid.

[Reference Example 1]
As a reference example, a plasma surface treatment was performed using only nitrogen (no reaction component), and other processing conditions and adhesion conditions were the same as in Example 1, and an attempt was made to produce a polarizing plate. However, the TAC film and the polarizing film were hardly adhered.

[Reference Example 2]
Plasma surface treatment was performed using only the inert gas argon (no reaction gas component), and the other treatment conditions and adhesion conditions were the same as in Example 1, and an attempt was made to produce a polarizing plate. However, the TAC film and the polarizing film were hardly adhered.

[Reference Example 3]
Plasma surface treatment was performed with a mixed gas of nitrogen 80 vol% and oxygen 20 vol%, and the other treatment conditions and adhesion conditions were the same as in Example 1, and an attempt was made to produce a polarizing plate. However, the TAC film and the polarizing film were hardly adhered.

[Reference Example 4]
Plasma surface treatment was performed with a mixed gas of 99 vol% nitrogen and 1 vol% ammonia, and the production of a polarizing plate was attempted in the same manner as in Example 1 except for the other treatment conditions and adhesion conditions. However, the TAC film and the polarizing film were hardly adhered.

[Reference Example 5]
Plasma surface treatment was performed with a mixed gas of 99 vol% nitrogen and 1 vol% acetylene, and other treatment conditions and adhesion conditions were the same as in Example 1, and an attempt was made to produce a polarizing plate. However, the TAC film and the polarizing film were hardly adhered.

[Reference Example 6]
Plasma surface treatment was performed with a wet gas in which 70 RH% H ₂ O was added to nitrogen, and the production of the polarizing plate was attempted in the same manner as in Example 1 except for the other treatment conditions and adhesion conditions. However, the TAC film and the polarizing film were hardly adhered.

The results of Examples 1 and 2 and Reference Examples 1 to 6 are summarized as shown in Table 1 below. “◎” in the column of adhesiveness indicates that the adhesiveness is very good. “◯” indicates that the adhesiveness is good. “Δ” indicates that the adhesiveness is slightly good. “X” indicates that the adhesiveness is poor.

A TAC film having a hard coat layer laminated on the front side surface was used, and the back side surface was subjected to plasma surface treatment under the same processing conditions as in Example 1.
The total light transmittance of the TAC film before the surface treatment was 92.9%, and the haze was 0.3%.
When the total light transmittance of the TAC film after the surface treatment was measured, it was 92.6 to 92.7%. Moreover, when the haze was measured, it was 0.2 to 0.3%, and it was confirmed that the hard coat layer was not damaged and good optical characteristics could be maintained.

The correlation between hydrophilicity and adhesiveness according to the types of reaction components in the reaction gas was investigated. As a reaction component, acetic acid, formic acid, vinyl acetate, butyl acrylate and the like were used as reference examples in addition to acrylic acid and methacrylic acid. Each reaction component was diluted with nitrogen (N ₂ ) to obtain a reaction gas. This reaction gas was introduced into the atmospheric pressure plasma space to be converted into plasma and brought into contact with the TAC film. The water contact angle before plasma surface treatment of the TAC film was 60 °. The contact angle with water of the TAC film after the surface treatment was measured.

FIG. 6 shows the measurement results of the contact angle after the surface treatment. The horizontal axis of FIG. This degree of processing Q is defined by the following formula 1 and standardized.
Q = (1 / v) × n × P (Formula 1)
Here, v is the relative movement speed of the TAC film with respect to the plasma discharge part of the plasma processing apparatus, n is the number of scans (number of times the TAC film is passed through the plasma discharge part), and P is the number of times of the plasma processing apparatus. This is the input power to the electrode.

  The smallest contact angle was acetic acid, followed by formic acid, followed by acrylic acid. The smaller the contact angle, the higher the hydrophilicity.

  Further, the TAC film and the PVA film after the plasma treatment with each of the above reaction gases were adhered. As the adhesive, a liquid in which (A) an aqueous solution of 5% by weight of polyvinyl alcohol and (B) an aqueous solution of 2% by weight of sodium carboxymethylcellulose were mixed at a volume ratio of (A) :( B) = 20: 1 was used. The average degree of polymerization of the polyvinyl alcohol (A) was 500.

  And adhesiveness was investigated. The adhesive evaluation was a hand evaluation in which the tester peeled off the TAC film and the PVA film by hand. The adhesiveness was the best when acrylic acid was used as the reaction component of the surface treatment, and the TAC film and the PVA film after adhesion could not be separated at all, and the materials were broken while both films were adhered. . The TAC film and the PVA film were most easily peeled off when the surface treatment was carried out with acetic acid and when it was carried out with formic acid, and only the adhesive strength of Post-It (registered trademark) was felt.

  From the above results, it has been found that even if the hydrophilicity is increased, the adhesiveness is not necessarily improved. From the standpoint of obtaining good adhesion, acrylic acid is currently the most preferred reaction component.

  In Example 5, the relationship between the difference ΔT between the ejection temperature Ta of the reactive gas and the temperature Tb of the TAC film and the adhesiveness was examined. A schematic configuration of the surface treatment apparatus used is shown in FIG.

Acrylic acid was used as a reaction component. Liquid acrylic acid was stored in the reaction component container 30 and the reaction component container 30 was adjusted to 40 to 50 ° C. A carrier gas of 100% nitrogen (N ₂ ) was supplied to the reaction component container 30 at a flow rate of 10 L / min to generate a reaction gas composed of acrylic acid and nitrogen. The reaction gas was jetted into the treatment space 29 from the jet nozzle 32 through the reaction gas supply path 31. The gas ejection temperature Ta was adjusted by the gas temperature adjusting means 39.

  The electrode structure of the plasma generation unit 2 is parallel plate electrodes 21 and 22. The lower ground electrode 22 also serves as a stage. A sample TAC film 12 was placed on the electrode 22, that is, the stage 22. The temperature of the stage 22 was adjusted by the film temperature adjusting means 27 comprising a hot water pipe, and consequently the film temperature Tb was adjusted. An atmospheric pressure plasma p was generated in the processing space 29 by supplying power to the electrode 21 while reciprocating (scanning) one of the electrodes 21 and 22 relative to the other. As a result, the reaction gas from the nozzle 32 was turned into plasma and brought into contact with the TAC film 12. The combinations of the gas ejection temperature Ta and the film temperature Tb are as shown in Table 2 below.

  The TAC film after the plasma surface treatment was adhered to the PVA film. The same adhesive as in Example 4 was used.

And adhesiveness was investigated. Adhesion evaluation was evaluated by five steps, which was a hand evaluation in which the tester peeled off the TAC film and the PVA film by hand.
The evaluation “1” is a level at which the entire adhesive surface peels cleanly and easily, and is 0.4 N / inch or less when converted to a 180 ° peel test.
The evaluation “2” is a level at which most of the bonded surface is peeled off, but is 1.0 N / inch or less when converted to a 180 ° peel test.
The evaluation “3” is a level at which the adhesive surface is partially peeled off. When converted to a 180 ° peel test, it is 3 N / inch or less, and there is a high possibility of material breakage during the peel test.
Evaluation "4" is a level where the part where the adhesive surface is peeled off but not peeled is 5 N / inch or less when converted into a 180 ° peel test, and the material is almost broken during the peel test.
Evaluation "5" is a level which hardly peels off and cannot be measured by a peel test.

The results are shown in Table 2 and FIG. The columns (a) to (l) in Table 2 correspond to FIGS. 8 (a) to (l), respectively.

The horizontal axis of each graph of FIGS. 8A to 8L is the processing degree Q defined by the following expression 2 (definition is different from that of the fourth embodiment).
Q = (P / S) × t (Formula 2)
Here, P is the input power [W] from the power source 23 to the electrode 21, and S is the area [cm ² ] of the discharge surface (lower surface in FIG. 7) of the electrode 21. Therefore, (P / S) is input power [W / cm ² ] per unit discharge area. t is the plasma irradiation time [sec] to the TAC film. The plasma irradiation time t is defined by the following equation.
t = n × L / v (Formula 3)
Here, n is the number of scans, L is the length [cm] of the electrode 21 in the scan direction (left-right direction in FIG. 7), and v is the scan speed [cm / sec].

  As shown in FIG. 8 (a) and Table 2 (a) column, when the difference between the gas ejection temperature Ta and the film temperature Tb (ΔT = Ta−Tb) is ΔT = + 17 ° C., the adhesive strength becomes the treatment degree Q. Regardless, the evaluation was “5”.

  As shown in FIG. 8B and Table 2B, even when the temperature difference was ΔT = + 12 ° C., the adhesive strength was evaluated as “5” regardless of the treatment degree Q.

  As shown in FIG. 8 (c) and Table 2 (c), even when the temperature difference was ΔT = + 10 ° C., the adhesive strength was evaluated as “5” regardless of the treatment degree Q.

  As shown in FIGS. 8D and 8E and Tables 2D and E, when the temperature difference was ΔT = + 7 ° C., the adhesive strength was evaluated as “4” to “5”.

  As shown in FIG. 8 (f) and Table 2 (f) column, when the temperature difference is ΔT = + 5 ° C., the adhesive strength was evaluated from “4” to “5”.

  As shown in FIGS. 8 (g) to (i) and Table 2 (g) to (i), when the temperature difference is ΔT = + 2 ° C., the adhesive force varies, and the evaluation is “4” to “5”. In some cases, the evaluation was “1” to “3”.

  As shown in FIGS. 8 (j) to (l) and Tables 2 (j) to (l), when the temperature difference ΔT is negative, the evaluation values of the adhesive strength were “1” to “3”.

  From the above results, it was found that the film temperature Tb needs to be lower than the gas ejection temperature Ta in order to sufficiently secure the adhesion between the TAC film and the PVA film. Moreover, it was confirmed that good adhesiveness can be obtained by setting the temperature difference ΔT = Ta−Tb to ΔT = + 5 ° C. or more. Furthermore, it was confirmed that better adhesiveness can be obtained by setting ΔT = + 10 ° C. or higher. It was found that the greater the temperature difference ΔT, the better the adhesion.

  This result is significantly different from general CVD (Chemical Vapor Deposition) which raises the substrate temperature. In this surface treatment, it is possible to cool or condense the adhesion improving group generated by the plasma conversion of the reaction gas on the surface of the TAC film to promote the bonding or adhesion of the adhesion enhancing group to the TAC film. It is presumed that this is effective.

  In Example 6, the relationship between the acrylic acid concentration in the reaction gas and the adhesiveness was examined. FIG. 9 shows a schematic configuration of the used surface treatment apparatus.

  A carrier of 100% nitrogen was sent from the carrier gas source 34 at 10 L / min. A part of this nitrogen gas was introduced into the reaction component container 30 through the carrier introduction path 35a, and the remainder was passed through the bypass path 35b to bypass the reaction component container 30. The dilution ratio of acrylic acid was adjusted by adjusting the ratio of the partial flow rate to the nitrogen gas introduction path 35a and the partial flow rate to the bypass path 35b. The temperature of the liquid acrylic acid Ac in the reaction component container 30 was adjusted to 40 ° C.

  The bypass path 35 b was joined to the reaction gas supply path 31 from the reaction component container 30. The gas after the merging was introduced into the treatment space 29 from the ejection nozzle 32 and turned into plasma. As shown in Table 3, the gas ejection temperature Ta was adjusted in the range of Ta = 32.8 to 33.8 ° C. according to the diversion ratio.

  The electrode structure was parallel plate electrodes 21 and 22. The TAC film 12 was placed on the lower electrode 22 that also serves as a stage. The temperature of the stage 22 and thus the film temperature Tb was adjusted to Tb = 25 ° C. The input power to the electrode 21 was 110V. One of the electrodes 21 and 22 was reciprocated (scanned) relative to the other. The moving speed was 10 m / min, and the number of reciprocations was 1 (2 scans).

The contact angle with water was measured at two points on the surface of the TAC film 12 after the surface treatment, and the average was taken.
Thereafter, the TAC film 12 and the PVA film were bonded. The same adhesive as in Example 4 was used. Then, the adhesiveness was evaluated. The evaluation method was the same manual evaluation as in Example 4.
The above operation was repeated three times, and three pieces of measurement data under the same conditions were acquired.

The results are shown in Table 3.

“Diversion ratio” in Table 3 is a flow rate to the introduction path 35a with respect to the entire nitrogen gas (10 L / min). The greater the “diversion ratio”, the higher the concentration of acrylic acid in the reaction gas after merging.
The water contact angle in Table 3 is an average of three measurement data.
“◯” in the adhesion evaluation indicates that the TAC film and the PVA film after adhesion cannot be separated at all, and the adhesion is good. “Δ” indicates that both films can be partially peeled and the adhesiveness is insufficient. “X” indicates that both the films can be peeled off and the adhesiveness is poor.

  As long as the diversion ratio was small, the contact angle with water was sufficiently small as long as it was not 0%. Thereby, it was confirmed that if the reaction gas contains a small amount of acrylic acid, the hydrophilicity increases.

  Regarding the adhesiveness, adhesion was insufficient or poor when the flow split ratio was 50% or less. Adequate adhesive strength was obtained when the diversion ratio was 80% or more. Therefore, it was confirmed that the higher the concentration of acrylic acid, the better the adhesiveness.

  In addition, when the density | concentration of acrylic acid is too high, a TAC film will become cloudy and it will become difficult to apply to optical films, such as a polarizing plate. There is also a risk of reaching the explosion limit. Therefore, the upper limit of the acrylic acid concentration is preferably set within a range where the TAC film does not become cloudy and, of course, does not reach the explosion limit.

  In Example 7, the relationship between the oxygen concentration in the reaction gas and the adhesiveness was examined. FIG. 10 shows a schematic configuration of the used surface treatment apparatus.

  A pure nitrogen gas was introduced into the reaction component container 30 from the carrier gas source 34 to obtain a reaction gas comprising a mixed gas of nitrogen and acrylic acid. The flow rate of nitrogen and thus the flow rate of the reaction gas was set to 10 L / min. The temperature of the liquid acrylic acid Ac in the reaction component container 30 was 40 ° C.

  The reaction gas (acrylic acid + nitrogen) was sent from the reaction component container 30 to the reaction gas supply path 31. The oxygen mixing path 37 was joined to the reaction gas supply path 31, and oxygen from the mixing path 37 was mixed into the reaction gas in the supply path 31. The mixing amount of oxygen was adjusted in the range of 0 to 2% by volume. This reaction gas was introduced into the treatment space 29 from the ejection nozzle 32 and turned into plasma. The gas ejection temperature Ta was Ta = 32 ° C. The input power to the electrode 21 was 110V.

  The TAC film 12 was placed on the stage 22. The temperature of the stage 22 and thus the film temperature Tb was set to Tb = 25 ° C. Therefore, the temperature difference ΔT between the reaction gas and the TAC film was ΔT = + 7 ° C.

  One of the electrodes 21 and 22R was reciprocated (scanned) relative to the other. The moving speed was 10 m / min, and the number of reciprocations was 1 (2 scans).

The TAC film 12 after the surface treatment was adhered to the PVA film. The same adhesive as in Example 4 was used. Then, the adhesiveness was evaluated. The evaluation method was the same manual evaluation as in Example 4.
The above operation was repeated three times, and trial data of the same condition (oxygen mixing amount) was obtained three by three.

The results are shown in Table 4. “◯”, “Δ”, and “×” in Table 4 indicate the degree of evaluation of adhesiveness, and the meaning thereof is the same as in Table 3.

  When the oxygen mixing amount was 0.5% or more, all had poor adhesion. When the oxygen mixing amount was 0.3%, the majority of the adhesion was good. When the oxygen mixing amount was 0.2% or less, the adhesion was all good. Thereby, it was confirmed that the oxygen concentration in the reaction gas for obtaining good adhesion is preferably 3000 ppm or less, and more preferably 2000 ppm or less.

  The present invention is applicable to the manufacture of polarizing plates for liquid crystal displays.

Claims (16)

Prior to adhering the second film containing triacetate cellulose as a main component to the first film made of polyvinyl alcohol-based resin, a surface treatment method applied to the second film,
Making the reaction gas into plasma and contacting the surface of the second film to be bonded to the first film;
The reactive gas contains acrylic acid or methacrylic acid, The film surface treatment method characterized by the above-mentioned.   The temperature of the portion of the second film that contacts the reactive gas (hereinafter referred to as “film temperature”) is lower than the ejection temperature of the reactive gas to the second film (hereinafter referred to as “gas ejection temperature”), The surface treatment method according to claim 1, wherein a difference between the gas ejection temperature and the film temperature is 5 ° C. or more. The film temperature is not less than room temperature;
The surface treatment method according to claim 2, wherein the reaction gas is set to a temperature lower than a flash point of acrylic acid or methacrylic acid and higher by 5 ° C. or more than the second film.   The surface treatment method according to claim 2, wherein a difference between the gas ejection temperature and the film temperature is 10 ° C. or more.   The surface treatment method according to claim 1, wherein an oxygen content of the reaction gas is 0 to 3000 ppm.   The surface treatment method according to claim 1, wherein the reaction gas is obtained by vaporizing acrylic acid or methacrylic acid in an inert gas.   The surface treatment method according to claim 1, wherein the reaction gas contains acrylic acid. A method for producing a polarizing plate comprising a first film made of a polyvinyl alcohol resin and a second film containing triacetate cellulose as a main component, the first film serving as a polarizing film, and the second film serving as a protective film. Because
A surface treatment step of bringing the reactive gas into plasma and bringing it into contact with the surface of the second film to be bonded to the first film;
Then, an adhesion step of adhering the first film and the second film with an adhesive,
The method for producing a polarizing plate, wherein the reaction gas contains acrylic acid or methacrylic acid.   In the surface treatment step, the temperature of the portion of the second film that contacts the reactive gas (hereinafter referred to as “film temperature”) is the ejection temperature of the reactive gas to the second film (hereinafter “gas ejection temperature”). The manufacturing method according to claim 8, wherein a difference between the gas ejection temperature and the film temperature is 5 ° C or higher. The film temperature is not less than room temperature;
The manufacturing method according to claim 9, wherein the reaction gas is set to a temperature lower than the flash point of acrylic acid or methacrylic acid and 5 ° C. or more higher than the film temperature.   The surface treatment method according to claim 9 or 10, wherein a difference between the gas ejection temperature and the film temperature is 10 ° C or more.   The production method according to any one of claims 8 to 11, wherein an oxygen content of the reaction gas is 0 to 3000 ppm.   The method according to claim 8, wherein in the surface treatment step, acrylic acid or methacrylic acid is vaporized in an inert gas to obtain the reaction gas.   The manufacturing method according to claim 8, wherein the reaction gas contains acrylic acid.   The functional layer is coated on the surface of the second film opposite to the surface to be bonded to the first film, and the functional layer is disposed on the discharge surface of one of the pair of electrodes used for the plasmatization. The reactive gas is introduced between the second film and the other electrode while the discharge surface is covered with the second film without any gap. The manufacturing method as described in. A surface treatment apparatus used in the surface treatment method according to claim 1, or used in a surface treatment step in the production method according to claim 8,
A plasma processing unit having a processing space in which the second film is disposed, and performing the plasma in or near the processing space;
A reaction gas supply system for supplying a reaction gas to the processing space;
Film temperature adjusting means for adjusting the temperature of the portion of the second film that contacts the reactive gas (hereinafter referred to as “film temperature”);
A gas temperature adjusting means for adjusting an ejection temperature of the reaction gas to the second film (hereinafter referred to as “gas ejection temperature”);
The film temperature adjusting means and the gas temperature adjusting means adjust the film temperature to be lower than the gas ejection temperature, and to adjust the difference between the gas ejection temperature and the film temperature to be 5 ° C. or more. A surface treatment apparatus characterized by the above.

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