JP2009057443A - Manufacturing method of adhesive composition having near-ir absorptivity, adhesive coating film and optical filter for pdp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the shortcoming that, when an adhesive composition for making an adhesive coating film having near-IR absorptivity is incorporated with cesium-containing tungsten oxide particles as a near-IR absorbing agent, the adhesive coating film faintly takes on a pale hue, to reduce the transparency and color purity, when applied to an optical filter for PDP and the like. <P>SOLUTION: The adhesive composition is manufactured by the two-step processes: (A) a primary process of preparing a primary dispersion process product by dispersing an adhesive composition containing cesium-containing tungsten oxide particles, an adhesive and a solvent into a dispersion having cesium-containing tungsten oxide particles dispersed therein, in such a state that part of the total amount of the adhesive and the total amount of the solvent are mixed, by using a bead mill; and (B) a secondary process of preparing a final adhesive composition by adding the remaining unmixed adhesive into the primary dispersion process product and agitating it. The adhesive coating film 1 by the above adhesive composition, formed on the substrate 2, is used as the optical filter 10 for PDP and the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a pressure-sensitive adhesive composition having near infrared absorption ability, a pressure-sensitive adhesive coating film using the same, and an optical filter for PDP.

  What gave the near-infrared absorptivity to the adhesive coating film may be requested | required. For example, it is an optical filter having an optical function such as an antireflection function, which is disposed in front of a PDP (plasma display panel). A near infrared ray having a wavelength of 800 to 1,200 nm is also radiated from the PDP, causing a commander used for remote operation of equipment such as other video recorders to malfunction. Therefore, if a near-infrared absorbing agent is added to the adhesive coating when the optical filter is disposed on the front surface of the PDP, malfunction can be prevented. As such a near-infrared absorber, in addition to an organic system (see Patent Document 1), recently, an inorganic system called tungsten oxide particles that can improve the deterioration of coloration and near-infrared absorption performance with the passage of time associated with an organic system is also proposed. (Patent Document 2, Patent Document 3, Patent Document 4).

JP 2006-257223 A JP 2006-282737 A International Publication No. 05/037932 JP 2006-201443 A

However, a system in which tungsten oxide particles are added as an inorganic near-infrared absorber is not completely transparent, and the transmitted color tone is often blue to green (Patent Documents 2 and 3).
Moreover, although there exists a cesium containing tungsten oxide particle which is a kind of tungsten oxide particle as a commercial item, the bluish-white of the reflected light peculiar to this particle | grain reduces a transmitted color purity. This situation is well understood when the adhesive coating film to which the particles are added is laminated on a black plate and observed. The black background appears pale.
Therefore, in applications where the adhesive coating is positioned in front of a display (image display device) such as a PDP, slight coloring (blue tint) and white tint are unintentional coloring with respect to the image on the display and dark portions of the image. The image quality is reduced, ie, the blackness of the image is reduced.
For this reason, although inorganic ultraviolet absorbers have good performance over time, they have not yet replaced organic near-infrared absorbers having excellent transparency, such as diimmonium compounds.

  In other words, the problem of the present invention is that the pressure-sensitive adhesive composition has a slight coloring (blue tint) and whiteness of the pressure-sensitive adhesive composition in which cesium-containing tungsten oxide particles are dispersed as an inorganic near-infrared absorber. It is to provide a method for producing a pressure-sensitive adhesive composition having near infrared absorption ability, a pressure-sensitive adhesive coating film, and an optical filter for PDP, which can prevent a decrease in transparency or a decrease in color purity.

  Therefore, in the present invention, the following manufacturing method, adhesive coating film, and optical filter for PDP are provided.

(1) A method for producing a pressure-sensitive adhesive composition comprising at least a cesium-containing tungsten oxide particle as an inorganic near-infrared absorber, and a pressure-sensitive adhesive and a solvent, wherein A) dispersion in which cesium-containing tungsten oxide particles are dispersed In a state where the liquid is mixed with a part of the total amount of the adhesive and the total amount of the solvent, it is dispersed by a bead mill to prepare a primary dispersion process product, and B) the remaining unmixed adhesive is primary. The manufacturing method of an adhesive composition including the secondary process of stirring and adjusting a final adhesive composition in addition to a dispersion | distribution process goods.

  By this method, even if the cesium-containing tungsten oxide particles are used as the inorganic near-infrared absorber in the near-infrared absorber to be dispersed and contained in the pressure-sensitive adhesive composition having near-infrared absorbing ability, the dispersion of the bead mill in the primary step, Agglomerated particles having a large particle size present in the particles can be reduced by dissociation, and re-aggregation of the particles dispersed in the primary process is also suppressed by the preparation in two stages of the primary process and the secondary process. As a result, the pressure-sensitive adhesive coating film formed with the pressure-sensitive adhesive composition is slightly colored (blue) and white (increased in haze) due to reflection of external light from the particles, and the transparency and color purity are reduced. Can be suppressed.

(2) A pressure-sensitive adhesive coating film having near-infrared absorption ability, formed using the pressure-sensitive adhesive composition produced by the production method of (1) above.
By this adhesive coating film, the effect described in the above (1) is obtained, and the effect that the transparency and color purity due to the bluish white can be suppressed can be obtained.

(3) An optical filter for PDP having a near-infrared absorbing ability, comprising the pressure-sensitive adhesive coating film of (2).
With this optical filter for PDP, the effects described in the above (1) and (2) can be obtained, and the effect that the transparency and color purity due to the bluish white can be suppressed can be obtained. This can prevent image quality deterioration such as unintentional coloring and blackness reduction of the display image.

In the method for producing a pressure-sensitive adhesive composition according to the present invention, even when cesium-containing tungsten oxide particles are included as an inorganic near infrared absorber, the decrease in transparency and color purity due to the unintentional bluish white unique to the particles can be suppressed. In addition, good transparency and no coloration in visible light can be ensured as in conventional organic near-infrared absorbers. In addition, since the near-infrared absorber is inorganic, the stability of performance over time such as light resistance and weather resistance is good.
For this reason, the pressure-sensitive adhesive coating using the pressure-sensitive adhesive composition and the optical filter for PDP using the pressure-sensitive adhesive coating suppress the undesirable blue-white taste of the pressure-sensitive adhesive coating as well as the near-infrared absorption ability. Therefore, it is possible to prevent image quality deterioration such as unintentional coloring and blackness reduction of an image displayed on the display.

<1. Method for producing pressure-sensitive adhesive composition>
First, the manufacturing method of an adhesive composition is demonstrated.

[Inorganic near-infrared absorber / cesium-containing tungsten oxide particles]
In the present invention, cesium-containing tungsten oxide particles are used as an inorganic near-infrared absorber to be contained in the pressure-sensitive adhesive composition. As the cesium-containing tungsten oxide particles, compound particles described in Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, and the like described above can be used. Moreover, the commercial item marketed from Sumitomo Metal Mining Co., Ltd. can also be used.

  Cesium-containing tungsten oxide particles are metal oxide particles that contain cesium in addition to tungsten as a tungsten oxide metal called tungsten oxide, and also contain metals other than tungsten. Oxide particles "are also referred to as" cesium-containing tungsten composite oxide fine particles "and the like because they are practically used as fine particles having a particle size of nm scale.

Tungsten oxide is represented by a chemical formula, WyOz, and cesium-containing tungsten oxide is represented by a chemical formula, CsxWyOz.
In the chemical formula of WyOz, y and z exhibit a desirable near-infrared absorptivity of high light transmittance in the visible light region and high near-infrared absorptivity. In Patent Document 2 and Patent Document 3, z / y is preferably 2.2 or more and 2.999 or less, that is, 2.2 ≦ z / y ≦ 2.999, from the viewpoint of near infrared absorption ability.
Similarly, in CsxWyOz, 0.001 ≦ x / y ≦ 1 and 2.2 ≦ z / y ≦ 3, and x / y is more preferably 0 in that it exhibits desirable near infrared absorption ability. .2 ≦ x / y ≦ 0.5, more preferably 0.2 ≦ x / y ≦ 0.33. A specific example is Cs _0.33 WO ₃ .

The cesium-containing tungsten oxide is represented by the chemical formula CsxWyOz, but composite tungsten oxide particles represented by the chemical formula MxWyOz in which Cs is replaced with another element M can also be applied as an inorganic near infrared absorber.
In the chemical formula MxWyOz, the M element is, for example, one or more of Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn.
In addition to the above, the element M is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag , Au, Zn, Cd, Al, Ga, Si, Ge, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os , Bi, or I may be used.

  The particle diameter of the cesium-containing tungsten oxide particles is preferably 500 nm or less, more preferably 100 nm or less, from the viewpoint of exhibiting a desirable near-infrared absorption ability that the light transmittance in the visible light region is high and the near-infrared absorption ability is high. When the particle diameter is large, the light transmittance in the visible light region is lowered, and the transparency (in visible light) is lowered. However, even if the particle diameter is less than or equal to the wavelength region of visible light (400 nm or less), the light and the color purity (non-colorability) are lowered due to the bluish color due to scattered light by Mie scattering or Rayleigh scattering. For this reason, in order to reduce the scattered light as much as possible, the particle diameter is preferably 200 nm or less, more preferably 100 nm or less. As described above, the cesium-containing tungsten oxide particles used in the present invention are submicron order fine particles.

  By the way, the particle diameter of the particles is not necessarily the same between the state of the particles in the dried powder and the state of being actually dispersed in the target medium (matrix). This is because the individually independent primary particles tend to aggregate together to become aggregated particles. Therefore, it has been common in the fine particle field to prevent the aggregation of the particle surface with a dispersant and suppress the generation of aggregated particles as much as possible.

However, it is still difficult to completely eliminate the presence of the agglomerated particles, and the particle size itself of a large number of particles usually has a distribution (distribution). If the particle diameter exceeds the above preferable particle diameter, the transparency may decrease depending on the degree of the particle diameter and the number of particles exceeding the preferable particle diameter.
However, in the present invention, transparency can be improved by reducing such a large particle size.

[Dispersion of cesium-containing tungsten oxide particles]
This dispersion is a liquid in which the above cesium-containing tungsten oxide particles are dispersed in a solvent (solvent), and contains other known contents as a dispersion such as a dispersant. In addition, as the dispersant, various surfactants such as a polymer type can be used. For example, one or more types such as an anionic compound, a cationic compound, a nonionic compound, and a polymer compound having an average molecular weight of 1000 or more are used. As the solvent, one or more of various solvents such as toluene and methyl ethyl ketone are used.

  The cesium-containing tungsten oxide particles may be used as a powder that has been dried from the beginning for dispersion in the primary step. However, since the particle diameter is very small as described above, the particles are dispersed in advance in the dispersion medium. It is preferable to use the dispersed liquid in terms of preventing generation of aggregated particles and obtaining stable quality. Moreover, if it is a state of a dispersion liquid, aggregation of the particle | grains at the time of storage, distribution | circulation, sale, etc. will be suppressed.

[Adhesives and solvents]
As the pressure-sensitive adhesive and solvent to be mixed in the primary step, conventionally known ones can be appropriately selected and used.

  The pressure-sensitive adhesive is transparent and more preferably uncolored from known pressure-sensitive adhesives. Adhesiveness, transparency, coating suitability, dispersibility of inorganic near infrared absorber particles, dispersion stability It can be selected as appropriate in consideration of the above. For example, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, and the like. Among these, an acrylic pressure-sensitive adhesive is a preferable type in terms of transparency, light resistance, weather resistance, and the like.

  As the solvent, various known solvents may be appropriately selected and used as the solvent for the coating liquid, such as aromatics such as toluene and xylene, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and other systems.

  The "total amount" of the solvent to be mixed in the primary process means that the dispersion of the cesium-containing tungsten oxide particles also contains the solvent, so the total amount of solvent contained in the final pressure-sensitive adhesive composition including this solvent component In contrast, the amount excluding the amount of solvent supplied from the dispersion, that is, the meaning of “total amount of added solvent” to be additionally mixed when the pressure-sensitive adhesive composition is prepared using the dispersion .

[Primary process to adjust the primary dispersion process product]
In the primary process, the dispersion liquid in which the cesium-containing tungsten oxide particles are dispersed, a part of the pressure-sensitive adhesive with respect to the total amount of the pressure-sensitive adhesive composition, and the total amount of solvent shortage with respect to the total amount of the pressure-sensitive adhesive composition were mixed. The mixed liquid in a state is dispersed by a disperser to prepare a primary dispersion process product.

  When a liquid mixture obtained by mixing a dispersion containing cesium-containing tungsten oxide particles with other necessary components such as a solvent and a pressure-sensitive adhesive is used as a pressure-sensitive adhesive composition, the liquid mixture is locally uneven in component concentration. Etc. (mixed shock) cause aggregation of particles, resulting in particles having a large particle size (aggregation). However, in the present invention, agglomerated particles generated at the time of mixing or the like are reduced in large particle size by dissociating the agglomeration of particles by this primary process. This seems to suppress the pale color of the adhesive coating film due to Mie scattering, Rayleigh scattering, etc. by the large particle size (see the transmission electron micrographs in FIGS. 2 and 3).

In general, as a disperser, there are a ball mill, a sand mill, a bead mill, an attritor, a homogenizer, etc., which are effective for reducing the particle size that affects the coloring phenomenon due to Mie scattering, Rayleigh scattering, etc. In addition, it is preferable to use a bead mill that is effective for nanometer-scale fine particle dispersion and can be dispersed by using a liquid dispersion. Also, the bead mill is preferable from the viewpoint of productivity in that high-speed dispersion is possible.
The particle size of the beads used in the bead mill is preferably as small as 100 μm or less in order to disperse nanometer-scale fine particles, and the material of the beads can be obtained and manufactured with such a particle size. Any of them may be used, for example, alumina or the like can be adopted. Also, zirconia, glass, and the like can be used as long as they have a particle size capable of dispersing the desired fine particles.

The amount of the adhesive and the amount of the solvent to be mixed in the primary process, and the remaining amount of the adhesive to be mixed in the secondary process, taking into account the material (dispersion, adhesive, solvent), viscosity, dispersion time, etc. What is necessary is just to determine suitably. The important thing is not to mix the whole amount of all adhesives with the dispersion from the beginning. As a result, the mixed shock is alleviated to suppress the generation of dispersed particles, and the particle diameter of particles such as aggregated particles can be reduced by dispersion using a bead mill. From the viewpoint of viscosity, the primary process is higher in viscosity than the dispersion and lower than the pressure-sensitive adhesive composition, and a part of the pressure-sensitive adhesive is mixed, and in the secondary process, the viscosity is adjusted to the viscosity of the final pressure-sensitive adhesive composition. To do.
In the primary step, a dispersant may be further mixed. As the dispersant, those listed in the above dispersion are used.

The amount of the pressure-sensitive adhesive added in the primary step is preferably 20 to 60% with respect to the total amount of the pressure-sensitive adhesive contained in the final pressure-sensitive adhesive composition. If the range is less than or exceeds the range, the intended effect cannot be obtained sufficiently.
Also, the dispersion time by the bead mill depends on the material (dispersion, adhesive, solvent), viscosity, etc., but if it is too small, a sufficient effect for solving the above problems cannot be obtained, and a preferable result is 2 hours or more. Has been obtained.

[Secondary process for adjusting final pressure-sensitive adhesive composition]
In the secondary process, the final pressure-sensitive adhesive composition is prepared by stirring the mixture of the primary dispersion process product obtained above and the remaining unmixed pressure-sensitive adhesive, or various necessary additives. To do. A known stirrer such as a mixer can be used for the stirring here.
Unlike the primary process, the stirring time may be as short as 10 minutes, for example.

  Thus, the obtained pressure-sensitive adhesive composition is transparent, has a near-infrared absorbing ability, and is blue due to the presence of an unintentional particle size of the cesium-containing tungsten oxide particles dispersed in the pressure-sensitive adhesive coating film. Taste and whiteness are suppressed.

  The amount of the cesium-containing tungsten oxide particles to be included in the pressure-sensitive adhesive composition is appropriately selected depending on the thickness of the pressure-sensitive adhesive coating film, the necessary near-infrared absorbing ability, the near-infrared absorbing ability of the near-infrared absorbing agent, and the like. The solid content ratio is usually 2 to 10% (mass basis, the same applies hereinafter) with respect to the adhesive coating film (adhesive composition solid content).

  In the pressure-sensitive adhesive composition, other additives can be added as necessary within the range not departing from the gist of the present invention. For example, in addition to various known additives in general pressure-sensitive adhesive compositions, as light stabilizers, ultraviolet absorbers such as benzotriazole compounds, benzophenone compounds, cerium oxide fine particles, various dyes for optical filter applications, Other additives. Among the dyes, specific examples for PDP applications include neon light absorbing dyes such as tetraazaporphyrin-based compounds having an absorption maximum in the vicinity of a wavelength range of 570 to 605 nm, color tone of display images by conscious coloring. Color tone-adjusting dyes for adjusting the color.

<2. Adhesive coating>
The pressure-sensitive adhesive coating film according to the present invention is a coating film formed by the pressure-sensitive adhesive composition manufactured by the above-described manufacturing method and having near-infrared absorbing ability, adhesiveness, and transparency. The near-infrared absorptivity depends on the application, but for display applications such as PDP, the near-infrared light transmittance of wavelengths of 800 to 1,200 nm is 20% or less from the viewpoint of preventing malfunctions due to near-infrared rays. ,preferable.

The pressure-sensitive adhesive coating film according to the present invention may be a single pressure-sensitive adhesive coating film or a product in which the pressure-sensitive adhesive coating film is laminated with a substrate. For example, an adhesive film using a resin film as a base material, an optical film coated with a resin film that does not peel off both surfaces of the adhesive coating film, and the like.
For the formation of the adhesive coating film, a known film forming method such as a coating method or a printing method may be appropriately employed. The pressure-sensitive adhesive composition is applied to various substrates and the like, and then dried to form a pressure-sensitive adhesive coating film.

Examples of articles having an adhesive coating include those having a configuration in which an adhesive coating is formed on a transparent resin film, and the adhesive coating is protected with a peelable release film. At this time, if the transparent resin film is also a release film with a release surface that can peel the adhesive coating film contact surface, only the adhesive coating film is laminated on other articles, excluding both side films of the adhesive coating film. Can do. In this case, since the transparent resin film is also peeled and removed, various known opaque films can be used instead.
If a specific example is shown, after apply | coating an adhesive composition to a 1st peeling film and drying and forming an adhesion coating film, the both sides of the structure which coat | covered the adhesion surface of the adhesion coating film with the 2nd peeling film An adhesive film having a release film configuration.

<3. Optical filter for PDP>
The optical filter for PDP according to the present invention is an optical filter for PDP having the above-mentioned adhesive coating film and having near-infrared absorption ability. As an optical filter function, at least, it has a near-infrared absorption ability by the adhesive coating film.
The PDP optical filter 10 illustrated in FIG. 1 has a configuration in which the above-described adhesive coating 2 is laminated on a transparent substrate 1. The substrate 1 may be a known transparent substrate such as a resin film (sheet), plate, or glass plate. Laminate and adhere to other substrates and articles with an adhesive coating.

Of course, as the optical filter for PDP, it is possible to adopt a configuration appropriately adopting various conventionally known functions such as other optical filter functions.
For example, the optical filter function includes a neon light absorption function that absorbs neon light of a PDP, a color correction function that corrects a display image to a desired color tone, an ultraviolet absorption function that absorbs ultraviolet light, and the like. It may be realized by adding a known additive that realizes these functions in the film, or may be provided as another optical filter layer.
Further, an optical functional layer that imparts an antireflection function (antiglare, antireflection, antiglare and antireflection), a surface protective layer for protecting the surface, a contamination prevention functional layer, an antistatic functional layer, etc. may be provided. An electromagnetic wave shielding layer such as a metal mesh that imparts an electromagnetic wave shielding function may be provided.
Each of these layers may be formed by a conventionally known material / method.

  Further, the present invention will be described in detail by examples and comparative examples. In addition, this invention is not limited to a following example. In the specification of the present invention, “%” means “mass%” based on mass unless otherwise specified. In the table, the mixing ratio is displayed up to two decimal places except for the Ne light absorbent.

[Example 1]
As a primary step, a pressure-sensitive adhesive using a (meth) acrylic resin as a part of the ratio 67.2% in the final pressure-sensitive adhesive composition (manufactured by Soken Chemical Co., Ltd., trade name “SK Dyne 2094”; A dispersion liquid (Sumitomo Metal Mining Co., Ltd.) having a glass transition temperature of 5 ° C., a number average molecular weight of 70,000, a molecular weight distribution of 2.6) and 20% and a cesium-containing tungsten composite oxide fine particle (Cs _0.33 WO ₃ ) content of 18.5% Product name “YMF-02”; average dispersed particle size 800 nm or less) 5.9%, solvent MIBK (methyl isobutyl ketone) 26.9% each added and mixed in a bead mill (beads made of alumina The product was dispersed for 2 hours using a product with an average particle diameter of 2 μm manufactured to produce a primary dispersion process product. In addition, 30% of the total amount of the pressure-sensitive adhesive was mixed in the primary step.

  Next, as a secondary process, 47.2% of the remainder of SK dyne 2094 and 0.17% of a curing agent (E-5XM, manufactured by Soken Chemical Co., Ltd.) are mixed with a mixer using the above-mentioned primary dispersion process product. The mixture was stirred for a minute to prepare a pressure-sensitive adhesive composition having near infrared absorption ability.

  Next, the pressure-sensitive adhesive composition was applied as a transparent resin film on an easy-adhesion-treated surface of a polyethylene terephthalate film (thickness 100 μm) so that the thickness after drying was 25 μm, and dried at 80 ° C. for 3 minutes. The coated film surface was coated with another same film on the easy adhesion treatment surface side to protect the coated film, and an adhesive coated film as a near-infrared absorbing layer was formed. The adhesive coating film is an optical film having a structure in which both surfaces thereof are covered with a transparent resin film.

  The component mixing ratios and performance results in each step are summarized in Table 1.

[Example 2]
A pressure-sensitive adhesive composition and an optical film were produced in the same manner as in Example 1 except that the dispersion in the bead mill in Example 1 was changed to 4 hours.

[Example 3]
In Example 1, the proportion of the pressure-sensitive adhesive to be mixed in the primary step was increased by 10% to 30%, and the proportion of the remaining pressure-sensitive adhesive to be mixed in the secondary step was increased by 37.2%. A pressure-sensitive adhesive composition and an optical film were produced in the same manner as in Example 1 except that the amount was reduced to 10%.

[Example 4]
In Example 3, a pressure-sensitive adhesive composition and an optical film were produced in the same manner as in Example 1 except that the dispersion in the bead mill was changed to 4 hours.

[Example 5]
In Example 1, the proportion of the pressure-sensitive adhesive to be mixed in the primary step was increased by 20% to 40%, and the proportion of the remaining pressure-sensitive adhesive to be mixed in the secondary step was increased by 27.2% accordingly. %, And a pressure-sensitive adhesive composition and an optical film were produced in the same manner as in Example 1 except that the dispersion in the bead mill was changed to 4 hours.

[Example 6]
A pressure-sensitive adhesive composition and an optical film were produced in the same manner as in Example 1 except that the dispersion in the bead mill in Example 1 was changed to 6 hours.

[Example 7]
A pressure-sensitive adhesive composition and an optical film were produced in the same manner as in Example 1 except that the dispersion in the bead mill in Example 1 was changed to 10 hours.

[Example 8]
In Example 1, a pressure-sensitive adhesive composition and an optical film were prepared in the same manner as in Example 1 except that 0.035% of Ne light absorber was further added in the secondary process.

[Comparative Example 1]
In Example 1, the two-stage adjustment of the primary process and the secondary process is omitted, and all the materials mixed in the primary process and the secondary process are mixed and used in the secondary process. To prepare a pressure-sensitive adhesive composition. Specifically, the pressure-sensitive adhesive is 67.2%, the dispersion is 5.9%, and MIBK is 26.9%. The stirring time of the mixer is the same 10 minutes. Moreover, the optical film was produced similarly to Example 1. FIG.

[Comparative Example 2]
In Example 1, 20% of the pressure-sensitive adhesive to be mixed in the primary step was 0%, and the pre-adhesion of the pressure-sensitive adhesive was eliminated, and the total amount was 67.2% in the secondary step. In the same manner as in Example 1, a pressure-sensitive adhesive composition and an optical film were produced.

[Comparative Example 3]
In Comparative Example 2, a pressure-sensitive adhesive composition and an optical film were produced in the same manner as in the above except that the dispersion in the bead mill was changed to 4 hours.

[Comparative Example 4]
In Example 1, a pressure-sensitive adhesive composition and an optical film were produced in the same manner except that the dispersion in the bead mill was changed to 1 hour.

[Comparative Example 5]
In Example 1, the ratio of the pressure-sensitive adhesive to be mixed in the primary process was reduced by 10% to 10%, and the ratio of the remaining pressure-sensitive adhesive to be mixed in the secondary process was reduced by 57.2 to 57.2. A pressure-sensitive adhesive composition and an optical film were produced in the same manner as in Example 1 except that the amount was increased by 10%.

[Comparative Example 6]
In Comparative Example 5, a pressure-sensitive adhesive composition and an optical film were produced in the same manner except that the dispersion in the bead mill was changed to 4 hours.

[Performance evaluation]
The blue and white taste was measured and evaluated as follows by dividing it into white and blue.

(1) Evaluation of blueness Blueness was measured and evaluated by the blue reflection index Z (30) during diffuse reflection. In accordance with JIS Z8722 (2000) “Color Measurement Method-Reflection and Transmission Object Color”, among the tristimulus values of the CIE XYZ color system, the Z value representing the intensity of blue is measured at a measurement angle of 30 degrees. evaluated. Specifically, in each Example and Comparative Example, a polyethylene terephthalate release film (thickness 50 μm) was bonded to the release treatment surface instead of the film covering the coating surface after drying the adhesive coating film. Thereafter, the release film was peeled off and then bonded to a commercially available black acrylic resin plate. Thereafter, the amount of reflected light is measured with a variable angle spectrophotometer at an incident angle of 0 ° (normal direction) and a measurement angle of 30 ° (normal direction), and the blue reflection index Z (30) is calculated from the reflected light intensity. As shown in FIG.
The Z value of the tristimulus value in the XYZ color system represents the intensity of blue, and is evaluated by this Z value. The light source used was a halogen lamp, and S (λ) z (λ) used was attached table 1.16 of JIS Z8722.

  In Equation 1, Z is a tristimulus value Z in the XYZ color system, K is a proportional constant, S (λ) standard light spectral distribution, and z (λ) is a color matching function in the XYZ color system. , R (λ) is the spectral solid angle reflectance of the measurement material, and λ is the wavelength (380 to 780 nm).

  If this measured value decreases by 10 or more in the production method of the present invention relative to the normal production method, a significant inhibitory effect on the increase in blueness can be obtained. Moreover, if this measured value is 9 or less, a desirable bluish elimination effect can be obtained.

2) Whiteness evaluation (haze measurement)
Whiteness was measured and evaluated with a turbidimeter (cloudiness meter) NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.

  If this measured value decreases by 3.5 or more in the production method of the present invention relative to the normal production method, a significant inhibitory effect on whiteness increase can be obtained. Moreover, if this measured value is 2.6 or less, a desirable whiteness elimination effect can be obtained.

[Details of component mixing ratio in each example and performance evaluation results]
It shows in the following Table 1-1 and Table 1-2. In addition, description of a hardening | curing agent mixing | blending is abbreviate | omitted for simplification, and the amount of hardening | curing agents and the amount of Ne light absorbers are not included in the total amount of 100%.

  As shown in Table 1-1 and Table 1-2, the bluish whiteness was suppressed in the Examples relative to the Comparative Examples, and performance comparable to that of the organic near-infrared absorbent was obtained.

Moreover, about the change of the dispersion state of the cesium containing tungsten oxide particle in an adhesive coating film, the photograph (magnification 45,000 times) observed with the transmission electron microscope is shown in FIG. One is shown in FIG. In the examples, particles having a large particle diameter were observed as compared with the comparative example, and the sparse region in which the particles were dispersed was reduced.
In addition, the dispersion state of the cesium-containing tungsten oxide particles does not mean that the dispersion state in the actual coating film is measured even when the liquid state of the primary dispersion process product is measured. It is not possible to deny the change in the dispersion state in the subsequent adjustment, coating, drying and other steps, or the dispersion measurement sample adjustment stage, and it is the adhesive film that directly affects the color of the adhesive film. This is because it is in a distributed state.

Sectional drawing which illustrates an example of the optical filter for PDP which has the adhesive coating film formed with this adhesive composition. The drawing substitute photograph (45,000 times transmission electron micrograph) which shows the dispersion state of the cesium containing tungsten oxide particle in the adhesion coating film of Example 1. FIG. The drawing substitute photograph (45,000 times transmission electron micrograph) which shows the dispersion state of the cesium containing tungsten oxide particle in the adhesion coating film of the comparative example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Adhesive coating film 2 Transparent base material 10 Optical filter for PDP

Claims (3)

A method for producing a pressure-sensitive adhesive composition comprising at least cesium-containing tungsten oxide particles as an inorganic near-infrared absorber, a pressure-sensitive adhesive, and a solvent,
A) A primary step of adjusting a primary dispersion process product by dispersing with a bead mill in a state where a part of the total amount of the adhesive and the total amount of the solvent are mixed in the dispersion liquid in which the cesium-containing tungsten oxide particles are dispersed. ,
B) A method for producing a pressure-sensitive adhesive composition, comprising a secondary step of adding the remaining unmixed pressure-sensitive adhesive to the primary dispersion step product and stirring to adjust the final pressure-sensitive adhesive composition.   A pressure-sensitive adhesive coating film having near-infrared absorption ability, formed using the pressure-sensitive adhesive composition manufactured by the manufacturing method according to claim 1. The optical filter for PDP which has the near-infrared absorptivity which has the adhesive coating film of Claim 2.