Acrylic acid plasma polymerization film and production method therefor

Abstract

To provide a novel acrylic acid plasma polymerization film excellent in heat resistance, solvent resistance, hardness, and transparency.SOLUTION: The present invention is an acrylic acid plasma polymerization film comprising C: 35-45 atom%, O: 7-12 atom%, and the balance being H and impurities. The plasma polymerization film exhibits, in an infrared absorption spectrum, for example, a peak intensity ratio satisfying C=O group / C-H group: 0.7-1.8 and C-O group / C-H group: 0.2-3.5, and in a Raman spectrum, for example, a peak intensity ratio satisfying C=C group / C-H group: 0.03-0.25 and C=C group / C=O group: 0.1-1.7. The plasma polymerization film has, for example, a film thickness of 20-1000 nm and a visible light transmittance of 85% or more.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present invention relates to an acrylic acid plasma-polymerized film obtained by polymerizing an acrylic acid-based monomer with plasma. [Background technology]

[0002] Acrylic resins are transparent and have excellent gloss, weather resistance, water resistance, and chemical resistance, making them used in a variety of products, one example of which is paint films. Acrylic paint films are usually formed by applying a paint made by dispersing or dissolving acrylic acid monomers in a solvent to the object to be treated, and then heating and drying the paint. This heating and drying process causes the monomers to thermally polymerize and become a polymer (resin).

[0003] In such a wet process film deposition method, it is difficult to reduce CO2 emissions. Also, since the method involves the evaporation of solvents, consideration must be given to the working environment. Therefore, a dry process film deposition method using plasma has been proposed, and the following patent documents contain relevant information. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2011-245743 [Patent Document 2] Patent Publication No. 2012-135879 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, a discharge plasma-treated layer is formed on a polyethylene substrate by introducing a mixed gas of argon and acrylic acid between parallel plate electrodes. In this case, the acrylic acid itself is converted into plasma and decomposed, so the layer formed on the substrate is not necessarily a polymerized acrylic acid. Furthermore, in Patent Document 1, the surface is washed with a solution after treatment, which is not a dry process.

[0006] In Patent Document 2, a silicon-based top coat layer is formed on a polycarbonate resin substrate by plasma CVD. The plasma CVD is performed between parallel electrodes in a vacuum chamber. Patent Document 2 does not mention the polymerization of acrylic acid-based monomers.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a new acrylic acid plasma-polymerized membrane. [Means for solving the problem]

[0008] The present inventors have succeeded in obtaining a new acrylic acid plasma-polymerized membrane by plasma-treating an acrylic acid monomer using a unique method. By expanding on this achievement, the present invention, which will be described below, has been completed.

[0009] <Acrylic acid plasma polymerized film> (1) The present invention is an acrylic acid plasma-polymerized membrane having the following component composition: C: 35 to 45 atomic %, O: 7 to 12 atomic %, balance: H and impurities

[0010] (2) The acrylic acid plasma-polymerized film of the present invention (also simply referred to as "plasma-polymerized film") has a component composition or molecular structure different from that of a conventional film (referred to as "thermally polymerized film") formed by thermally polymerizing an acrylic acid-based monomer (also simply referred to as "monomer").

[0011] The plasma-polymerized membrane of the present invention is thought to be formed by not only linear addition polymerization but also three-dimensional crosslinking, resulting in the monomers being polymerized into a three-dimensional network. This is thought to result in the plasma-polymerized membrane containing, for example, ketones, aldehydes, esters, etc., which are not originally present in the acrylic acid-based monomers from which some of the carbonyl groups are derived.

[0012] Such plasma-polymerized membranes can exhibit superior heat resistance, solvent resistance, hardness, transparency, and other properties compared to conventional thermally polymerized membranes. Furthermore, because plasma-polymerized membranes can be formed using a dry process, they can also contribute to reducing CO2 emissions and preserving the environment. Furthermore, because the plasma-polymerized membranes of the present invention can be formed under various environments (e.g., atmospheric pressure), they can be used on a variety of substrates.

[0013] Incidentally, the reason and mechanism by which plasma-polymerized films with compositions and structures that cannot be obtained by conventional thermal polymerization were obtained is unclear. At present, it is thought that the high-energy electrons of the plasma dissociate and activate acrylic acid monomers to an appropriate degree, promoting addition polymerization and crosslinking, and that the monomers polymerize to form polyacrylic acid with a larger molecular weight, which is then deposited and formed into a film on the workpiece surface, resulting in the formation of the plasma-polymerized film of the present invention.

[0014] <Manufacturing method / processed material> The present invention can also be understood as a method for producing an acrylic acid plasma-polymerized film. For example, the present invention may be a method for producing the above-mentioned acrylic acid plasma-polymerized film by combining plasma generated from a first gas and a second gas containing an acrylic acid-based monomer.

[0015] The present invention can also be understood as a treated object having an acrylic acid plasma-polymerized film formed on the surface of a substrate (a base material). The plasma-polymerized film is not limited to a top coat (upper layer) and may be an undercoat (lower layer), etc. The plasma-polymerized film may be a single layer or multiple layers, and may be a mixture or laminate of multiple types of monomers with different components or structures.

[0016] "others" (1) "Plasma polymerization" includes not only linear addition polymerization of acrylic acid monomers but also cross-linking reactions between side chains. The polymerization reaction may also proceed on the surface to be treated.

[0017] (2) As used in this specification, "up / down (upstream / downstream)" refers to the direction along which plasma or raw material gas (acrylic acid-based monomer) flows, and is not related to the orientation of the sky and the earth unless otherwise specified. For example, the surface on the upstream side is referred to as the upper surface, and the surface on the downstream side is referred to as the lower surface.

[0018] (3) Regarding the wavenumber, "around X cm , , , , , [Figure 1B] , [Figure 3] , [Figure 2B] , [Figure 2A] " means, if specifically stated, for example, within a range of X ± 50 cm -1 , X ± 35 cm -1 or X ± 25 cm -1 .

[0019] Around atmospheric pressure means, for example, a pressure (P) that satisfies 0.01P0 ≦ P ≦ 1.1P0 with respect to atmospheric pressure (P0), regardless of the gas species. "Sub-atmospheric pressure" is a pressure less than atmospheric pressure, for example, 0.01P0 ≦ P < P0. Based on standard atmospheric pressure (P0 = 1.01325 × 10 5 Pa ≒ 1 × 10 5 Pa), for example, 1 × 3 Pa ≦ P ≦ 1 × 5 Pa may be considered as around atmospheric pressure. 5

[0020] (4) As used in this specification, "x~y" includes the lower limit value x and the upper limit value y unless otherwise specified. Any numerical value included in various numerical values or numerical ranges described in this specification can be used as a new lower limit value or upper limit value to newly establish a range such as "a~b". As used in this specification, "x~ynm" means xnm~ynm unless otherwise specified. The same applies to other unit systems.

Brief Description of Drawings

[0021] [Figure 1A] It is a schematic diagram illustrating a plasma polymerization apparatus. [Figure 1B] It is a cross-sectional view of the main part thereof. [Figure 2A] It is an infrared absorption spectrum of each sample. [Figure 2B] It is a partial enlarged view thereof. [Figure 3] It is a Raman spectrum of each sample. ​ DETAILED DESCRIPTION OF THE INVENTION

[0022] One or more components arbitrarily selected from the present specification may be added to the above-described components of the present invention. The contents described in this specification apply to both objects (films, coatings, processed objects, devices, etc.) and methods (manufacturing methods, film-forming methods, processing methods, etc.) as appropriate. Method-related components can also be components related to objects. Which embodiment is best depends on the target, required performance, etc.

[0023] <Acrylic acid monomer> Plasma-polymerized films are formed by bringing acrylic acid-based monomers (also simply referred to as "monomers") into contact with plasma. Examples of such monomers include acrylic acid (C3H4O2), acrylic acid esters, and methacrylic acid esters. Examples of acrylic acid esters include methyl acrylate (C4H6O2) and ethyl acrylate (C5H8O2). Examples of methacrylic acid esters include methyl methacrylate (C5H8O2).

[0024] <Film composition> The plasma polymerized film has, for example, the following component composition: Unless otherwise specified, the components (concentrations) referred to in this specification are atomic ratios (simply indicated as "%)" relative to the entire film (100 at%).

[0025] C is, for example, 35 to 45%, 36 to 44%, or 36.5 to 43%. O is, for example, 7 to 12%, 8 to 11%, or 9 to 10.5%. Depending on the components of the plasma source gas (first gas) and the raw material gas (second gas), the remainder is, for example, H and (unavoidable) impurities. Incidentally, as an example, the C: 33.3% and 13.3% (theoretical values) of both the monomer and polymer of ethyl acrylate are ethyl acrylate.

[0026] The component composition of such a plasma polymerized film is identified by, for example, Rutherford Backscattering Spectrometry (RBS), Hydrogen Forward Scattering Spectrometry (HFS), Nuclear Reaction Analysis (NRA), or the like, depending on the element to be identified.

[0027] 《Membrane structure》 Plasma polymerized films have functional groups (CH groups, C=O groups, CO groups, C=C groups, etc.) that correspond to their raw materials (acrylic acid monomers), and are identified by the following spectroscopic methods.

[0028] (1) Infrared absorption spectrometry (IR) According to the IR spectrum, the plasma polymerized film has a peak at 1400 cm -1 The CH group has a peak near 1150 cm -1 The C-O group has a peak near 1700 cm -1 It has a C=O group with a peak near

[0029] The ratio of the peak intensity of the C═O group to the peak intensity of the CH group (C═O group / CH group) is, for example, 0.7 to 1.8, 0.8 to 1.6, or 1.1 to 1.4. The ratio of the peak intensity of the CO group to the peak intensity of the CH group (CO group / CH group) is, for example, 0.2 to 3.5, 0.7 to 1.5, or 1 to 1.3.

[0030] Focusing on the C=O group of the plasma polymerized film, for example, the wavenumber of the peak top is 1720 to 1733 cm -1 , or 1724~1730cm -1 The half-width is 26-47cm -1 , or 28-38cm -1 is.

[0031] (2) Raman Spectroscopy According to Raman spectroscopy, plasma polymerized films exhibit a Raman spectrum of, for example, 3000 cm -1 The CH group has a peak near 1700 cm -1 The C=O group has a peak near 1600 cm -1 It has a C=C group with a peak near

[0032] The ratio of the peak intensity of C=C groups to the peak intensity of CH groups (C=C groups / CH groups) is, for example, 0.03 to 0.25, 0.05 to 0.18, or 0.06 to 0.16. The ratio of the peak intensity of C=C groups to the peak intensity of C=O groups (C=C groups / C=O groups) is, for example, 0.1 to 1.7, 0.2 to 1.4, or 0.4 to 1.

[0033] The half-width of the C=O group is, for example, 28 to 35 cm -1 or 29-33cm -1 The half-width of the C=C group is, for example, 30 to 100 cm -1 or 45-80cm -1 is.

[0034] (3)Functional group The plasma-polymerized membrane may contain one or more aldehyde (groups), ketone (groups), or ester (groups), which are at least part of the carbonyl groups contained in the monomers. Such a plasma-polymerized membrane may have a three-dimensional structure due to advanced crosslinking.

[0035] 《Characteristics》 The thickness of the plasma polymerized film is not limited, but is, for example, 20 to 1000 nm, 50 to 700 nm, or 100 to 400 nm.

[0036] The plasma polymerized film has a transmittance in the visible light region (wavelength: 400 to 800 nm) of, for example, 85 to 100%, 88 to 98%, or 90 to 95%.

[0037] 《Film formation》 The plasma polymerized film is obtained, for example, by joining (mixing) plasma generated from a first gas and a second gas containing an acrylic acid-based monomer.

[0038] (1) First gas (plasma source gas) The first gas is, for example, mainly composed of an inert gas (rare gas (Ar, Ne, He, etc.), N2, etc.). Hydrogen may be included to promote polymerization and crosslinking. The flow rate ratio (hydrogen / inert gas) is, for example, 0.3 to 3 or 0.5 to 2.

[0039] (2) Second gas (raw material gas) The second gas may contain the raw material acrylic acid-based monomer in the form of gas (vapor) or atomized particles. The second gas may also contain a solvent for the acrylic acid-based monomer (e.g., water). The second gas may be supplied in a manner suitable for the plasma supply form (e.g., elongated linear or layered).

[0040] (3) Treatment atmosphere The atmosphere may be a vacuum or a (sub)atmospheric pressure atmosphere (e.g., 1000 Pa to 50000 Pa). Processing in a processing furnace (chamber) can prevent gas leakage, etc. For example, if a plasma is irradiated onto a surface to be processed in an atmospheric or subatmospheric pressure atmosphere and a second gas is supplied to the plasma, a polymerized film is obtained on the surface to be processed. Polymerization of a plasma-converted monomer or chemical vapor deposition may occur on the surface to be processed.

[0041] (4) Equipment The plasma polymerized film is formed (manufactured) using, for example, a plasma polymerization apparatus equipped with a plasma head that supplies plasma and a raw material gas head that supplies the second gas.

[0042] The plasma head includes, for example, a first electrode, an intermediate insulator, and a second electrode stacked from the upstream side where the first gas is supplied, and has a through hole that passes through the first electrode, the intermediate insulator, and the second electrode to allow the first gas to flow. When a voltage is applied between the first electrode and the second electrode, plasma generated between the electrodes is ejected from the lower opening of the through hole.

[0043] The source gas head merges or mixes the second gas downstream of the plasma. The outlet of the plasma head and the outlet of the source gas head are, for example, elongated slit-shaped. By moving (scanning) such plasma head and source gas head relative to the workpiece, a uniform plasma polymerized film can be efficiently formed on the surface of the workpiece.

[0044] The power source that generates the electric field between the first and second electrodes may be a DC power source, an AC power source, or a pulse power source. The applied voltage (peak-to-peak value / maximum-minimum voltage difference) is, for example, 200 to 3000 V or 400 to 1500 V. The frequency of the AC power source or pulse power source is, for example, 0.1 kHz to 20 kHz or 1 kHz to 10 kHz. [Example]

[0045] The plasma polymerized membrane was fabricated as a prototype and its characteristics were evaluated. The present invention will be explained in more detail with reference to such specific examples.

[0046] "Device" An overview of the plasma polymerization apparatus S (simply referred to as "apparatus S") used for film formation is shown in FIG. 1A, and a cross section of its essential parts is shown in FIG. 1B. Both figures are collectively referred to as "FIG. 1." For ease of explanation, the directions of the arrows shown in FIG. 1A will be referred to as the front-to-back direction, the left-to-right direction, or the up-to-down direction, as appropriate. The up-to-down direction is along the flow of the first gas or plasma within the apparatus S, with the upstream side being the top and the downstream side being the bottom.

[0047] The apparatus S includes an introduction part 1, a plasma head 2, a raw material gas head 3, a stage 4 on which a workpiece w (object to be processed) is placed, a power supply 6, a chamber 7, and a vacuum pump 8. The introduction part 1, the plasma head 2, the raw material gas head 3, and the stage 4 are housed (stored) in the chamber 7.

[0048] (1) The introduction part 1 has an introduction port 11 for introducing a first gas g0, which is a plasma source, and a cover 12 having a substantially rectangular parallelepiped shape.

[0049] The first gas g0 taken into the cover 12 through the inlet 11 is introduced into the communication hole 20. The cover 12 is made of metal (for example, stainless steel), and is electrically connected to an electrode plate 221, which will be described later.

[0050] (2) The plasma head 2 includes an electrode plate 221 (first electrode), an insulating plate 212 (intermediate insulator), and an electrode plate 222 (second electrode), which are stacked in this order from above, and an insulating tube 211 (external insulator) that surrounds the outer peripheries of these. The inner circumferential surface of the insulating tube 211 is in close contact with the outer circumferential (end) surfaces of the electrode plate 221, the insulating plate 212, the electrode plate 222, and the introduction portion 1 (cover 12). The insulating plate 212, the electrode plate 221, and the electrode plate 222 are rectangular, and the insulating tube 211 is square cylindrical.

[0051] The plasma head 2 further has a slit-shaped through-hole 20 that penetrates approximately the center in the vertical direction and extends in the horizontal direction. The through-hole 20 is formed by a hole 2210 in the electrode plate 221, a hole 2120 in the insulating plate 212, and a hole 2220 in the electrode plate 222.

[0052] When a high voltage is applied between electrode plate 221 and electrode plate 222, a discharge (mainly a glow discharge) occurs between inner wall surface 2210a of hole 2210 and inner wall surface 2220a of hole 2220, generating plasma p within communication hole 20. Plasma p is pushed out by first gas g0 flowing from upstream to downstream within communication hole 20, and is ejected from elongated plasma discharge hole 23 which is the opening on the lower end side of communication hole 20.

[0053] Inner wall surface 2210a of hole 2210 and inner wall surface 2220a of hole 2220 are flush with each other all around in the vertical direction. Inner wall surface 2120a of hole 2120 is offset outward (in the front-to-back direction) relative to these inner wall surfaces, forming a recessed depression 20a.

[0054] (3) The source gas head 3 is arranged adjacent to the plasma head 2 and supplies the source gas g m The nozzle 31 has a tip opening that is an elongated slit-shaped source gas discharge hole 33. mis a monomer gas that reacts with the plasma p to polymerize.

[0055] The raw material gas discharge hole 33 is arranged near the downstream side of the plasma discharge hole 23. The plasma discharge hole 23 and the raw material gas discharge hole 33 extend parallel to each other in the longitudinal direction (the left-right direction in FIG. 1A) and have approximately the same shape. The raw material gas discharge hole 33 is arranged slightly away from the surface of the workpiece w and close to the plasma discharge hole 23. The raw material gas discharge hole 33 is arranged so that the raw material gas g is discharged into the flow of the plasma p. m It is slightly inclined towards the workpiece w so as to align with the

[0056] (4) The chamber 7 is evacuated by a vacuum pump 8 to create a quasi-atmospheric atmosphere. The stage 4 includes a base 41, a heater 42 built into the base 41, a drive mechanism (not shown) that moves the base 41 in the planar directions (X-axis direction and Y-axis direction), and a control device (not shown) that controls the heater 42 and the drive mechanism. The heater 42 and the control device manage the temperature of the workpiece w placed on the base 41. The drive mechanism and the control device manage the position of the workpiece w placed on the base 41, adjust the processing speed, etc.

[0057] The power supply 6 is a DC pulse power supply device that generates a pulsed voltage at a desired frequency. The power supply 6 applies a voltage required to generate plasma between the electrode plate 221 and the electrode plate 222. The electrode plate 222 and the stage 4 (base 41) are both grounded, and electricity is applied to the electrode plate 221 via the cover 12.

[0058] The disclosures in Japanese Patent Application Laid-Open Nos. 2021-82491 and 2022-127786 were used as reference for the plasma head 2. The contents of these patent documents are also incorporated into this specification as appropriate.

[0059] 《Film formation》 Using the apparatus S, a plasma-polymerized film of ethyl acrylate (monomer) was formed on a substrate (stainless steel or polycarbonate) as the workpiece w. The stainless steel substrate was used for spectroscopic analysis, and the polycarbonate substrate was used for transmittance measurement. Specifically, the procedure is as follows.

[0060] (1) Equipment specifications The electrode plates 221 and 222 were made of rolled stainless steel (SUS304), and the insulating tube 211 and insulating plate 212 were made of sintered alumina (Al2O3). The electrode plate 221 was 5 mm thick, the electrode plate 222 was 1 mm thick, and the insulating plate 212 was 1 mm thick (t). The insulating tube 211 had a thickness of 5 mm and a height (L) of 33 mm. The opening shapes of the plasma discharge hole 23 and the raw material gas discharge hole 33 were 1 mm × 100 mm. The vertical distance from the surface of the workpiece w to the plasma discharge hole 23 was 6 mm. The angle between the raw material gas discharge hole 33 and the plasma discharge hole 23 and the mutual flow direction was 90°.

[0061] (2) Film formation conditions Using the apparatus S, plasma polymerized films of Samples 1 to 8 were formed under the conditions shown in Table 1. During this process, the inside of the chamber 7 was evacuated by the vacuum pump 8 to 1333 Pa (absolute pressure).

[0062] The second gas was ethyl acrylate vapor, which was generated by reducing the pressure in a container containing ethyl acrylate from atmospheric pressure (gauge pressure: -0.09 MPa), and supplying the vaporized ethyl acrylate vapor to the chamber through a mass flow meter.

[0063] A pulse voltage (rectangular wave) was applied between the electrode plates 221 and 222. The voltage (peak to peak value) and frequency are shown in Table 1.

[0064] The substrate irradiated with the monomer-containing plasma started at room temperature of 25° C. and was raised toward the final temperature. The substrate temperature (final temperature) when removed from chamber 7 is also shown in Table 1.

[0065] (3) Comparative Example (Sample C1) As a comparative example, toluene was added to ethyl acrylate and heated to 90°C, and 1% by mass of azobisisobutyronitrile (AIBN) as a polymerization initiator was added. This mixture was then applied to a substrate and dried to produce a thermally polymerized film on the substrate.

[0066] "measurement" (1) Ingredients The components of the polymerized film of each sample were measured by RBS, HFS, and NRA. A tandem electrostatic accelerator, Pelletron 5SDH-2 (manufactured by National Electrostatics Corporation), was used for the measurements. The specific measurement conditions were as follows: NRA measurement, RBS / HFS simultaneous measurement, Incident ions: 4He++ 4He++, Incident energy: 3710 keV 2300 keV Incident angle: 0deg 75deg, scattering angle: 160deg 160deg, recoil angle: -30deg Specimen current: 4nA 3nA, beam diameter: 1mmφ 1mmφ, in-plane rotation: None None, Irradiation dose: 56 μC (however, samples 1 to 3: 0.2 μC, sample 4: 3.8 μC)

[0067] To reduce damage to the sample, measurements were taken at multiple points with different positions, and the integrated data was used for evaluation. The results are also shown in Table 1.

[0068] (2) Structure The IR spectrum and Raman spectrum of each polymer film were measured as follows.

[0069] The IR spectrum was measured using a Fourier transform infrared spectrophotometer (FTIR: Thermo Fisher Scientific FT-IR NICOLET iS50 + infrared microscope CONTINU μM). Specifically, the chemical structure of the film on the metal substrate (made of stainless steel) was analyzed by infrared microreflection. The analysis conditions were: 100 μm square, Au mirror blank, MCT detector, 64 accumulations, measurement resolution 4 cm.-1 , n=3 (number of measurements).

[0070] The peak areas of the main functional groups in the spectrum were calculated, and the area ratios of each peak were determined as follows. -1 The half-width of the carbonyl group peak in the vicinity and its peak top wavenumber were calculated. The baseline (B) and area (A) reading wavenumbers are as follows: [Peak area] Alkyl group (-CH:2900cm -1 Near ): (B) and (A) are both 3040 - 2800 cm -1 Carbonyl group (-C=O: 1725cm -1 Near ): (B) and (A) are both 1800 - 1600 cm -1 Ether group (-CO:1200cm -1 Nearby): (B) and (A) are both 1355 - 980 cm -1

[0071] [Half-width of main carbonyl group peak] 1815-1600 cm -1 A baseline was drawn, and the peak width at half the absorbance height of a vertical line drawn from the peak top to the baseline was taken as the half-value width.

[0072] The Raman spectrum was measured using a Raman spectrophotometer (NRS-7500 manufactured by JASCO Corporation). Specifically, Raman analysis was performed directly on each polymer film. Taking into account variations, analysis was performed at two to three randomly selected points under conditions suitable for the sample. An example of the analysis conditions is as follows: Excitation wavelength: 532 nm, exposure time: 5 seconds, number of accumulations: 60, CDD: DU970P_BVF, Grating: L400, slit width: φ25μm, aperture: φ4000μm, Objective lens: 100x, Laser intensity: 0.7mW

[0073] The overall IR spectrum is shown in Figure 2A, an enlarged view of a key portion is shown in Figure 2B, and the Raman spectrum is shown in Figure 3. Based on each spectrum, the peak intensity ratio (PI), half-width (HW), peak top wavenumber (PT), etc. were determined. The results are summarized in Table 1.

[0074] (3) Transmittance The transmittance of each polymerized film to visible light (wavelength: 400-800 nm) was measured using a UV-visible-near-infrared spectrophotometer (SolidSpec-3700, manufactured by Shimadzu Corporation). The transmittance of each film was 85-90%.

[0075] (4) Film Thickness The film thickness of each sample was measured by the step method using a Surfcorder (ET4000A manufactured by Kosaka Laboratory Co., Ltd.) The film thickness of each sample was 30 to 500 nm.

[0076] "evaluation" (1) Ingredient composition As can be seen from Table 1, the thermally polymerized film of sample C1 had the same C: 33% and O: 13% as the raw material monomer. However, the plasma-polymerized film had more C and less O. It is thought that the plasma-polymerized film had promoted three-dimensional cross-linking between the addition-polymerized linear polymers.

[0077] (2) Structure As can be seen from Figure 2 or Table 1, when observing the peak position (wavenumber) representing the C=O group in the IR spectrum, the plasma-polymerized film was shifted to a lower wavenumber side than the thermally polymerized film, and the half-width was also wider.

[0078] In addition, the CH group (1400 cm -1 CO group (around 1150cm -1 The peak intensity ratio (CO group / CH group) of the plasma-polymerized film was significantly smaller than that of the thermally polymerized film.

[0079] As can be seen from Figure 3 or Table 1, in the Raman spectrum, the C=C group (1600 cm -1The half-width of the peak (near the peak) of the plasma-polymerized film was much larger than that of the thermally polymerized film.

[0080] In addition, the plasma polymerized film has a higher C=O group (1700cm) than the thermally polymerized film. -1 C=C group (around 1600cm -1 The peak intensity ratio (C=C group / C=O group) of the C=C group around 1000 nm was quite large.

[0081] These analytical results revealed that the plasma-polymerized membrane of the present invention is significantly different from conventional thermally polymerized membranes in terms of component composition and structure, which is thought to be because the plasma-polymerized membrane of the present invention contains more ketones, aldehydes, etc. than thermally polymerized membranes, due to the three-dimensional promotion of polymerization and crosslinking.

[0082] [Table 1]

Claims

1. An acrylic acid plasma polymerized film having the following component composition: C: 35 to 45 atomic%, O: 7 to 12 atomic%, Remainder: H and impurities

2. The C—O group (1150 cm ) determined from the peak position of the infrared absorption spectrum -１ around 1400 cm -１ around 1700 cm -１ The acrylic acid plasma-polymerized membrane according to claim 1, comprising:

3. The acrylic acid plasma-polymerized film according to claim 2, which satisfies the following peak intensity ratio: C=O group / C-H group: 0.7 to 1.8 C-O group / C-H group: 0.2 to 3.5

4. The acrylic acid plasma-polymerized membrane according to claim 2 or 3, wherein the C═O groups satisfy the following: Peak top wave number: 1720 to 1733 (cm -１ ) Half width: 26-47 (cm -１ )

5. C—H groups (3000 cm ) determined from the peak positions of the Raman spectrum -１ around 1700 cm -１ around 1600 cm) and C=C groups -１ The acrylic acid plasma-polymerized membrane according to claim 1, comprising:

6. The acrylic acid plasma-polymerized film according to claim 5, which satisfies the following peak intensity ratio: C=C group / C-H group: 0.03 to 0.25 C=C group / C=O group: 0.1 to 1.7

7. The acrylic acid plasma-polymerized film according to claim 5 or 6, which satisfies the following half-value width: C=O group: 28~35 (cm -１ ) C=C group: 30~100 (cm -１ )

8. 2. The acrylic acid plasma polymerized film according to claim 1, wherein the film thickness is 20 to 1000 nm.

9. 9. The acrylic acid plasma polymerized film according to claim 1, which has a transmittance of 85% or more for light having a wavelength of 400 to 800 nm.

10. 2. The acrylic acid plasma-polymerized membrane of claim 1, which comprises one or more of an aldehyde, a ketone, or an ester.

11. 2. A method for producing the acrylic acid plasma-polymerized film of claim 1, comprising joining a plasma generated from a first gas with a second gas containing an acrylic acid-based monomer.

12. The method for producing an acrylic acid plasma polymerized film according to claim 11, wherein the film is formed on a surface to be treated under an atmosphere of atmospheric pressure or subatmospheric pressure.

13. 12. The method for producing an acrylic acid plasma-polymerized film according to claim 11, wherein the first gas is an inert gas containing hydrogen.

14. 12. The method for producing an acrylic acid plasma-polymerized film according to claim 11, wherein the acrylic acid-based monomer is at least one of acrylic acid and acrylic acid ester.

15. the polymerization is carried out using a plasma polymerization apparatus including a raw material gas head for supplying the second gas and a plasma head for supplying the plasma; the source gas head mixes the second gas into a downstream side of the plasma; 12. The method for producing an acrylic acid plasma polymerized film according to claim 11, wherein the plasma head comprises a first electrode, an intermediate insulator, and a second electrode stacked from the upstream side of the supply of the first gas, and a through hole penetrating the first electrode, the intermediate insulator, and the second electrode to allow the first gas to flow, and wherein a voltage is applied between the first electrode and the second electrode to generate plasma, which is discharged from the lower opening side of the through hole.

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