JP2008209574A - Double-sided adhesive tape for shielding near infrared ray, and optical filter for pdp (plasma display panel) - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-sided adhesive tape for shielding near infrared rays which is inexpensively manufactured by reducing the quantity of a near-infrared absorbing pigment to be incorporated. <P>SOLUTION: An adhesive agent layer and a strippable film comprising a transparent resin are successively laminated on both surfaces of a near-infrared shielding layer formed by laminating a selective reflection layer and a near-infrared absorbing layer comprising a transparent resin layer in which a near infrared absorbing pigment is dispersed. The selective reflection layer is formed from a one formed by laminating a high molecular solidified body layer of a cholesteric liquid crystal on one surface of a transparent base material. The near infrared absorbing pigment comprises two kinds of a long wave near infrared absorbing pigment and a short wave near infrared absorbing pigment which respectively have absorption ability to a different wavelength band in 800-1,100 nm absorption wavelength, wherein it is preferable that the near infrared absorbing pigment for long wave length is one kind selected from diimmonium base compounds and the near infrared absorbing pigment for short wave length is a pigment comprising one or more kinds selected from cyanin based compounds and thionyl nickel complex salt based compounds. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a near-infrared shielding double-sided pressure-sensitive adhesive film used for a PDP (plasma display panel). More specifically, it can be manufactured at low cost by reducing the amount of near-infrared-absorbing dyes in the bonding of functional films for various display optical filters (hereinafter simply referred to as “optical filters”). The present invention relates to a double-sided pressure-sensitive adhesive film for shielding near infrared rays.
In the present invention, “near infrared” refers to light having a wavelength of 800 to 1100 nm.

  In recent years, in displays such as a plasma display panel (PDP), electromagnetic waves generated from the front of the display have a bad influence on the human body and malfunction of surrounding electronic devices has become a problem. At the same time, countermeasures against the influence of the display on the surrounding area are becoming more important.

In particular, in PDPs where demand is increasing as large thin displays, in addition to electromagnetic wave shielding films, near-infrared absorbing films for preventing malfunctions of various remote control switches using the near-infrared wavelength region, UV light absorbing film used to prevent near-infrared absorbers used for near-infrared absorbing film over time, neon light cut film for adjusting color tone in the visible light region, and external light reflected on the surface of optical filters An antireflection film or the like for preventing this is combined and configured according to the required function.
By using these films as optical filters for displays, measures are taken to improve the image appearance and to reduce the influence on the surroundings.

  Conventionally, various transparent conductive films and electromagnetic wave shielding films have been developed in response to the requirement to prevent the electromagnetic waves generated from the display from leaking to the outside and adversely affecting the human body. Known electromagnetic shielding materials can be broadly classified into two types: an electromagnetic shielding material made of a transparent conductive film and an electromagnetic shielding material made of a conductive metal mesh. Among these, the electromagnetic shielding material using a transparent conductive film is superior in transparency to the electromagnetic shielding material using a metal mesh, but has a large surface resistivity and inferior electromagnetic shielding performance. For this reason, in the use which shields the electromagnetic waves from the apparatus which generate | occur | produces strong electromagnetic waves, such as PDP, the electromagnetic wave shielding material by a metal mesh is preferable.

  Further, as a method for producing an electromagnetic wave shielding material using a conductive metal mesh, (1) a metal foil is bonded to a transparent substrate, or a metal thin film is deposited on the transparent substrate, and then a conductive metal is obtained by a photolithographic method. An etching method for forming a pattern (for example, refer to Patent Document 1), and (2) a thin metal pattern formed with developed silver produced by a photographic method, and then plated on the developed silver thin film to form a conductive metal Examples thereof include a photographic silver-plating method for forming a pattern (see, for example, Patent Document 2).

On the other hand, as a near-infrared absorbing film, a near-infrared absorbing filter in which a near-infrared absorbing layer made of a near-infrared absorbing composition made of a dithiol nickel compound and / or a diimmonium compound is formed on one side of a transparent substrate is disclosed ( (See Patent Document 3).
Also disclosed is a near-infrared absorbing film having at least two near-infrared absorbing layers each absorbing in the near-infrared region between wavelengths of 800 to 1100 nm, and comprising at least three layers including a substrate. (See Patent Document 4).
Furthermore, a near-infrared absorption filter formed by laminating a composition in which a near-infrared absorption pigment is dispersed in a binder resin on a substrate is disclosed (see Patent Document 5).
Further, an optical filter that reflects and blocks near infrared rays using a plurality of cholesteric liquid crystal polymer solidified layers is disclosed (see Patent Document 6).
Japanese Patent Laid-Open No. 10-075087 International Publication No. 2004/007810 Pamphlet JP 2005-054031 A JP 2002-156521 A JP 2000-227515 A JP 2000-056115 A

  In the prior art, there has been a demand for an optical filter that can be reduced in weight and can be manufactured at low cost so as to avoid an increase in weight due to an increase in the size of a PDP (plasma display panel) screen.

  Each of the near-infrared absorbing films incorporated in the optical filters described in Patent Documents 3 to 5 is obtained by laminating a near-infrared absorbing layer containing a near-infrared absorbing pigment on one side of a transparent substrate. However, since the near-infrared absorbing layer is laminated directly on one side of the transparent substrate, the functionality to form an optical filter by peeling only the near-infrared absorbing layer from the transparent substrate supporting the near-infrared absorbing layer. There was a problem that it could not be transferred to a film.

  Moreover, the wavelength selective reflection layer using the polymer solidified layer having a plurality of cholesteric liquid crystal structures incorporated in the optical filter described in Patent Document 6 is for reflecting the left circularly polarized component of light in at least the near infrared band. It is necessary to provide a selective reflection layer and a selective reflection layer for reflecting the right circularly polarized component of light. In addition, in order to increase the near-infrared reflectance of a specific wavelength band to 90% or more, the directions of the optical axes of the two selective reflection layers for reflecting the left and right polarized components (the spiral axis of the cholesteric periodic structure) must be completely set. There was a problem that a precise structure matched was necessary.

  Thus, in the prior art, in laminating the functional film for optical filters, by using the selective reflection layer A composed of a polymer solidified body layer having a cholesteric liquid crystal structure and the near-infrared absorbing dye (B) in combination, By reducing the amount of the near-infrared absorbing dye B mixed, a near-infrared absorbing double-sided adhesive film that can be manufactured at low cost has not been provided.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the double-sided adhesive film for near-infrared shielding which can be manufactured cheaply by reducing the mixing amount of the near-infrared absorption pigment | dye B. FIG.

  In order to solve the above problems, the present invention provides a selective reflection layer A composed of a polymer solidified layer having a cholesteric liquid crystal structure that transmits visible light and selectively reflects near infrared rays in a specific wavelength range, An adhesive layer and a release film made of a transparent resin are sequentially laminated on both surfaces of a near-infrared shielding layer formed by laminating a near-infrared absorbing layer B made of a transparent resin layer in which an infrared absorbing dye is dispersed. A double-sided pressure-sensitive adhesive film for shielding near infrared rays is provided.

The selective reflection layer A is preferably formed by laminating a plurality of polymer solidified layers having a plurality of cholesteric liquid crystal structures each having a different helical pitch on one surface of a transparent substrate.
The selective reflection layer A is formed by laminating a single layer of a polymer solidified layer having a cholesteric liquid crystal structure in which the helical pitch is continuously changed in the thickness direction of the layer on one surface of the transparent substrate. Is preferred.
The solidified polymer layer having a cholesteric liquid crystal structure preferably selectively reflects either the left circularly polarized component or the right circularly polarized component in the near infrared band.

The near-infrared absorbing dye is preferably composed of two types of absorbing dye for a long wavelength and an absorbing dye for a short wavelength, each having an absorption maximum in different wavelength bands in an absorption wavelength band of 800 nm to 1100 nm. .
The near-infrared absorbing dye for long wavelengths is one selected from diimmonium salt compounds, and the near-infrared absorbing dye for short wavelengths is phthalocyanine compounds, cyanine compounds, thiol nickel complex compounds It is preferable that it is 1 type, or 2 or more types of pigment | dyes selected from these.
As a function of the near-infrared shielding double-sided adhesive film in which the selective reflection layer A and the near-infrared absorbing layer B are laminated, the near-infrared transmittance in the wavelength region of 850 to 1100 nm is 20% or less, more preferably 10% or less. It is desirable that it be lowered.

  The present invention peels off the release film made of a transparent resin on both sides constituting the double-sided adhesive film for shielding near infrared rays, and the antireflection film or antiglare film, electromagnetic wave shielding film, ultraviolet absorption film, and neon light cut film. The optical filter for PDP formed by bonding to 1 type, or 2 or more types of functional films selected from is provided.

  By using the double-sided pressure-sensitive adhesive film for shielding near infrared rays of the present invention, a near-infrared absorbing film in which a near-infrared absorbing layer containing a near-infrared absorbing dye B is directly laminated on one side of a transparent substrate in the prior art is used as an optical filter. Compared to the case of bonding in the constituent layers, the selective reflection layer A and the near-infrared absorbing layer B are used in combination, so that the amount of the expensive near-infrared absorbing dye B can be reduced and the near-infrared shielding is achieved. Can be produced at low cost.

In the manufacturing process of the optical filter using the double-sided pressure-sensitive adhesive film for shielding near infrared rays of the present invention, the selective reflection layer A and the near-infrared absorbing layer B are laminated without peeling off the release film made of a transparent resin. It is possible to carry out a performance measurement test of the near-infrared shielding layer, and the work efficiency is excellent.
In addition, the near-infrared shielding double-sided adhesive film of the present invention is a transparent resin that covers the outermost surface during the storage period from the manufacturing process until it is used by being bonded to various functional films as an optical filter. The release film made of 1 functions as a protective film, and has an effect of protecting the internal selective reflection layer A and the near infrared absorption layer B from damage.

The present invention will be described below with reference to the drawings based on the best mode.
FIG. 1 is a schematic cross-sectional view showing a configuration of a double-sided pressure-sensitive adhesive film for shielding near infrared rays according to the present invention.
FIG. 2 shows an optical filter for PDP formed by peeling off a release film made of a transparent resin on both sides of a double-sided adhesive film for shielding near infrared rays in FIG. 1 and bonding it to a functional film such as an antireflection film or an electromagnetic wave shield film. It is a typical sectional view showing an example.
FIG. 3 is a schematic cross-sectional view showing another example of an optical filter for PDP used by peeling off a release film made of a transparent resin on both sides of the double-sided adhesive film for shielding near infrared rays of FIG.
FIG. 4 is a schematic cross-sectional view showing the configuration of a near-infrared absorbing film using a near-infrared absorbing dye in the prior art.

  FIG. 1 shows a structural example of a double-sided pressure-sensitive adhesive film 1 for shielding near infrared rays according to the present invention. A polymer solidified body layer 4a having a cholesteric liquid crystal structure is laminated on a transparent substrate 5 to form a selective reflection layer. Further, a near-infrared absorbing layer 4b is further laminated thereon to form a near-infrared shielding layer, and a double-sided adhesive film layer 7 formed by laminating adhesive layers 3 and 6 on both sides of the near-infrared shielding layer is made of a transparent resin. The release films 2 and 8 are laminated.

(Release film made of transparent resin)
The transparent material constituting the release films 2 and 8 made of a transparent resin is a plastic film made of a resin that is transparent in the visible region, has flexibility, and preferably has good heat resistance.
Examples of such plastic films include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), diacetate resins, triacetate resins, acrylic resins, polycarbonate resins, triacetyl cellulose, polystyrene, polyolefins, polyurethane resins. , A single layer or a composite film having a thickness of 10 to 600 μm made of polyvinyl chloride, polyimide resin, polyamide resin or the like.
More preferable as the release films 2 and 8 made of a transparent resin are those in which a release agent is applied to one side of the transparent plastic film. The release agent is not particularly limited. For example, resins such as paraffin wax, acrylic, urethane, silicon, melamine, urea, urea-melamine, cellulose, benzoguanamine, and surfactants may be used alone or in combination. Examples thereof include those formed by applying a coating material dissolved in an organic solvent containing water as a main component or water to the transparent plastic film by a normal printing method such as gravure printing or screen printing, and drying.

(Adhesive layer)
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layers 3 and 6 may be any of a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, etc., among which an acrylic pressure-sensitive adhesive is particularly preferable. Thereby, it is excellent in transparency and the weather resistance of the adhesive layers 3 and 6 can be maintained favorable.
Examples of such an acrylic pressure-sensitive adhesive component include a low-Tg main monomer that provides tackiness, a high-Tg comonomer that provides adhesion and cohesion, and a functional group for improving crosslinking and adhesion. Those composed of a group-containing monomer (monoethylenically unsaturated monomer) and the like are used.
Examples of the main monomer include alkyl acrylates such as ethyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, cyclohexyl acrylate, benzyl acrylate, butyl methacrylate, and methacrylic acid. Examples thereof include methacrylic acid alkyl esters such as 2-ethylhexyl, cyclohexyl methacrylate and benzyl methacrylate, and these can be used alone or in combination of two or more.
Examples of the comonomer include vinyl group-containing compounds such as methyl acrylate, methyl methacrylate, ethyl methacrylate, vinyl acetate, vinyl propionate, vinyl ether, styrene, acrylonitrile, and methacrylonitrile.
Examples of functional group-containing monomers include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meta ) Acrylate, 4-hydroxybutyl (meth) acrylate, N-methylolacrylamide, hydroxyl group-containing monomers such as allyl alcohol, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) ) Tertiary amino group-containing monomers such as acrylate, amide group-containing monomers such as acrylamide and methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide N- ethoxymethyl (meth) acrylamide, N-t-butyl acrylamide, N- substituted amide group-containing monomers such as N- octyl acrylamide, an epoxy group-containing monomers such as glycidyl methacrylate.
By using such a material, it is excellent in adhesiveness, cohesiveness, and durability, and arbitrary quality and characteristics according to the application can be obtained by selecting the kind and combination of monomers.
The weight average molecular weight of the pressure-sensitive adhesive component is preferably 300,000 to 3,000,000, more preferably 500,000 to 2,000,000. If the molecular weight of the pressure-sensitive adhesive component is too low, the pressure-sensitive adhesive strength and cohesive strength of the pressure-sensitive adhesive will be poor, and sufficient blister resistance will not be obtained. Workability of sticking deteriorates.
Moreover, it is preferable that the glass transition point (Tg) of an adhesive component is -20 degrees C or less. When the glass transition point exceeds −20 ° C., the pressure-sensitive adhesive becomes hard depending on the use temperature, and the adhesiveness may not be maintained.
As the above-mentioned pressure-sensitive adhesive, either a crosslinked type or a non-crosslinked type can be used. In the case of the crosslinking type, examples include methods using various crosslinking agents such as epoxy compounds, isocyanate compounds, metal chelate compounds, metal alkoxides, metal salts, amine compounds, hydrazine compounds, aldehyde compounds, etc. The functional group is appropriately selected.
The curable component contained in the pressure-sensitive adhesive layers 3 and 6 is not particularly limited, and examples thereof include those having thermosetting properties such as epoxy resins, phenolic resins, melamine resins, and polyester resins, and those having radiation curable properties described later. However, those having radiation curability are particularly preferable. As a result, the curable component can be cured at room temperature or low temperature in a very short time, and the handleability is excellent.

The term “radiation curable” as used herein means, for example, that molecular chain growth or crosslinking reaction is induced by irradiation with ultraviolet rays, laser beams, α rays, β rays, γ rays, X rays, or electron beams, and the curable components are cured. Means nature.
Such a radiation curable component is not particularly limited, but for example, a component having an acrylic monomer or oligomer is preferable. Thereby, an adhesive layer having excellent weather resistance can be formed.
Examples of such radiation curable acrylic monomers and / or oligomers include hexanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and pentaerythritol tri (meth) acrylate. , Trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, urethane acrylate, epoxy acrylate, polyester acrylate, and the like. These may be used alone or in combination.

Further, the acrylic monomer or oligomer preferably includes a reactive monomer or oligomer having an acryloyl group, and more preferably has two or more acryloyl groups. By including two or more acryloyl groups, the network structure is sufficiently formed, the cohesiveness of the pressure-sensitive adhesive is further improved, and a good pressure-sensitive adhesive layer is obtained.
0.05-50 weight part is preferable with respect to 100 weight part of said adhesive components, and, as for content of curable components, such as the said radiation-curable component, 0.1-20 weight part is more preferable. If the amount of the curable component is too small, the effect of suppressing foaming and swelling due to the generated gas may not be sufficiently obtained due to the cohesive force of the pressure-sensitive adhesive. On the other hand, when there is too much quantity of a sclerosing | hardenable component, the adhesive layer 5 becomes hard too much and there exists a possibility that adhesive force may fall.
When the curable component is blended with the pressure-sensitive adhesive component, those having good compatibility with the pressure-sensitive adhesive component are preferable. In addition, the curable component can be used as a copolymer with the main polymer of the pressure-sensitive adhesive component.
When the radiation-curable component is cured by ultraviolet irradiation or the like, the pressure-sensitive adhesive layers 3 and 6 are preferably light-transmitting, for example, substantially transparent or translucent (colorless or colored) is preferable. Thus, the pressure-sensitive adhesive layers 3 and 6 can be easily cured.
When the radiation curable component is cured by ultraviolet irradiation or the like, a polymerization initiator may be added. For example, benzoin, benzoin methyl ether, benzoin ethyl ether, o-benzoylbenzoic acid methyl-p-benzoin ethyl ether, Benzoins such as benzoin isopropyl ether and α-methylbenzoin, dimethylbenzyl ketal, trichloroacetophenone, acetophenones such as 2,2-diethoxyacetophenone and 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, Propiophenones such as 2-hydroxy-4′-isopropyl-2-methylpropiophenone, benzophenone, methylbenzophenone, p-chlorobenzophenone, p-dimethylaminobenzophenone, etc. Benzophenone compounds, 2-black thio xanthone, 2-ethyl thioxanthone, thioxanthone such as 2-isopropylthioxanthone, benzyl, dibenzosuberone, alpha-acyl oxime esters.

The addition amount of such a polymerization initiator is preferably about 0.5 to 30 parts by weight, and more preferably about 1 to 20 parts by weight with respect to 100 parts by weight of the radiation curable component.
On the other hand, when the radiation curable component is cured by electron beam irradiation, the addition of the polymerization initiator is not necessary, but in this case, since the curing reaction is significantly inhibited by the presence of oxygen, nitrogen or the like is not necessary. It is necessary to carry out under an active gas atmosphere. Or it is preferable to carry out in the state which stuck the peeling films 2 and 7 consisting of transparent resin.
Moreover, a polymerization accelerator can be used together with the above polymerization initiator. Examples of such a polymerization accelerator include 4,4′-bis (diethylamine) benzophenone, ethyl N-dimethylaminobenzoate, and dimethylethanolamine. , Glycine and the like.
The polymerization initiator and polymerization accelerator as described above can be added in microcapsules in order to improve the stability during storage.
Furthermore, various additives such as a tackifier, a softener (plasticizer), a filler, an anti-aging agent, a silane coupling agent, and the like can be added as other additives as necessary.
Examples of the tackifier include rosin and derivatives thereof, polyterpene, terpene phenol resin, coumarone-indene resin, petroleum resin, styrene resin, and xylene resin.
Examples of the softening agent include liquid polyether, glycol ester, liquid polyterpene, liquid polyacrylate, phthalic acid ester, trimellitic acid ester, and the like.
Examples of the method for forming the pressure-sensitive adhesive layers 3 and 5 having the pressure-sensitive adhesive component and the curable component as main components include coating with a die or a comma coater. Examples of the coating method include a flow coater, a knife coater, a roll coater, and dipping.
The thickness (dry film thickness) of the pressure-sensitive adhesive layers 3 and 5 is not particularly limited, but is preferably about 5 to 100 μm, particularly about 10 to 60 μm.

(Selective reflection layer)
The selective reflection layer A is obtained by laminating a polymer solidified layer having a cholesteric liquid crystal structure on one surface of a transparent substrate.
In order to increase the near-infrared reflectance of a specific wavelength band to 90% or more, the directions of the optical axes (the spiral axes of the cholesteric periodic structure) of the two selective reflection layers for reflecting the left and right polarization components are perfectly matched. There is a problem that a precise structure is required.
Therefore, in the present invention, the solidified polymer layer having the cholesteric liquid crystal structure selectively reflects either the left circularly polarized component of light in the near infrared wavelength band or the right circularly polarized component of light. Inevitably, the reflectance of the near infrared ray by the selective reflection layer A is 50% at the maximum, so the reflectance of the selective reflection layer A is preferably 30 to 50%.

When the selective reflection layer A is formed by laminating a plurality of polymer solidified layers having a plurality of cholesteric liquid crystal structures with different helical pitches on one surface of a transparent substrate, the spiral of each polymer solidified layer When the pitch length is Pnm and the refractive index is N, out of the light having a wavelength corresponding to the value NP obtained by multiplying the helical pitch length by the refractive index, it coincides with the helical twist direction of each polymer solidified layer. Reflects only circularly polarized light. Since the reflectance in the selective reflection layer A depends on the number of turns of the spiral pitch, it is preferable that the thickness of each polymer solidified layer is 3 to 6 in the spiral pitch.
The selective reflection layer A is formed by laminating a single layer of a polymer solidified layer having a cholesteric liquid crystal structure in which the helical pitch continuously changes in the thickness direction of the layer on one surface of the transparent substrate. But it ’s okay.

The near-infrared shielding double-sided pressure-sensitive adhesive film of the present invention finally has a selective reflection layer A and a near-infrared absorbing dye B in combination, so that the near-infrared transmittance in the wavelength region of 850 to 1100 nm is 20% or less, More preferably, it is reduced to 10% or less.
The solidified polymer layer having a cholesteric liquid crystal structure is prepared by a known method as disclosed in Patent Document 6 above, and a cholesteric liquid crystal having a reflection wavelength band of 800 to 1100 nm can be obtained.
On the transparent substrate, a polymer solidified layer having a cholesteric liquid crystal structure is laminated to obtain a selective reflection layer.
The transparent substrate is a plastic film made of a resin that is transparent in the visible region, has flexibility, and preferably has good heat resistance.
Examples of such plastic films include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), diacetate resins, triacetate resins, acrylic resins, polycarbonate resins, triacetyl cellulose, polystyrene, polyolefin, polyurethane. Examples thereof include a single layer or a composite film having a thickness of 10 to 300 μm made of a resin, polyvinyl chloride, polyimide resin, polyamide resin, polyvinyl alcohol resin, cellulose acetate resin and the like.

In the selective reflection layer, a plastic film that has been subjected to stretching treatment or rubbing treatment or the like so as to improve the alignment regularity of the liquid crystal is preferably used.
Further, the transparent substrate used in the present invention is, for example, corona treatment, plasma treatment, UV, etc. in order to improve the adhesion with the polymer solidified body layer having a cholesteric liquid crystal structure laminated on the transparent substrate. May be subjected to surface treatment.
A coating solution in which a material composition for forming a polymer solidified body layer having a cholesteric liquid crystal structure is dissolved in an organic solvent is applied by a known method. For example, it can be applied by a roll coating method, a gravure coating method, a bar coating method, a die coating method, a slit coating method, or the like.

After the coating liquid is applied to the transparent substrate, the liquid crystal is oriented in a certain direction while being dried at a predetermined temperature at which the cholesteric liquid crystal structure is expressed, and a cholesteric liquid crystal structure having a spiral structure is formed.
Such a cholesteric liquid crystal structure is fixed by polymerizing the liquid crystal molecules of the liquid crystal material composition using the energy of heating or ionizing radiation, and becomes a polymer solidified body layer having a cholesteric liquid crystal structure.
By the above operation, a selective reflection layer A in which a polymer solidified layer having a cholesteric liquid crystal structure is laminated on at least one surface of a transparent substrate can be obtained.
Adjustment of near-infrared reflectance in a double-sided adhesive film for shielding near-infrared rays is affected by the number of helical pitches of the cholestec liquid crystal polymer in the selective reflection layer, but the number of helical pitches is not particularly limited and is required. What is necessary is just to select suitably by the balance with the addition amount of a near-infrared absorption pigment | dye so that it may adapt to the near-infrared transmittance which is.

(Near-infrared absorbing layer)
The near-infrared absorbing layer B made of a transparent resin layer in which the near-infrared absorbing dye is dispersed can be formed by dispersing the near-infrared absorbing dye in a binder made of a transparent resin.
Specific examples of near-infrared absorbing dyes include immonium salt compounds, diimmonium salt compounds, aminium salt compounds, nitroso compounds and their metal complexes, cyanine compounds, squarylium compounds, thiol nickel complex compounds, aminothiol nickel compounds Complex salt compounds, phthalocyanine compounds, naphthalocyanine compounds, triarylmethane compounds, naphthoquinone compounds, anthraquinone compounds, amino compounds, carbon black, antimony oxide, tin oxide doped with indium oxide, Group 4 of the periodic table, Examples thereof include oxides, carbides or borides of metals belonging to Group 5 or Group 6.

The near-infrared absorbing dye of the present invention has two or more kinds of a long-wavelength near-infrared absorbing dye and a short-wavelength near-infrared absorbing dye each having absorption ability in different wavelength bands in the absorption wavelength band of 800 nm to 1100 nm. It preferably consists of a dye.
The near-infrared absorbing dye for long wavelengths is one selected from diimmonium salt compounds, and the near-infrared absorbing dye for short wavelengths is phthalocyanine compounds, cyanine compounds, thiol nickel complex compounds It is preferable that it is 1 type, or 2 or more types of pigment | dyes selected from these.

The near-infrared absorbing layer B in which the near-infrared absorbing dye is dispersed is formed by dispersing the near-infrared absorbing dye in a binder made of a transparent resin.
The glass transition temperature (Tg) of the binder resin is preferably -80 to 160 ° C. As a result, the weather resistance of the binder resin itself is improved, the near infrared shielding performance of the near infrared shielding coating film is maintained, and the weather resistance and physical properties of the near infrared shielding coating itself are further improved. Become. Preferably, it is -50-130 degreeC, More preferably, it is 20-110 degreeC, More preferably, it is 40-100 degreeC.
Examples of the binder resin include (meth) acrylic resin, (meth) acrylic urethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, melamine resin, urethane resin, styrene resin, and alkyd resin. Modification of resins, phenolic resins, epoxy resins, polyester resins, (meth) acrylic silicone resins, alkylpolysiloxane resins, silicone resins, silicone alkyd resins, silicone urethane resins, silicone polyester resins, silicone acrylic resins, etc. Examples include fluororesins such as silicone resins, polyvinylidene fluoride, and fluoroolefin vinyl ether polymers. Thermoplastic resins may be used, and thermosetting resins, moisture curable resins, UV curable resins, electron beam curable resins, etc. Resin may be used Also, organic binder resins such as synthetic rubber such as ethylene-propylene copolymer rubber, polybutadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber or natural rubber; silica sol, alkali silicate, silicon alkoxide and their (hydrolysis) Conventionally known binder resins such as inorganic binders such as condensates and phosphates may be mentioned. These may be used alone or in combination of two or more. Among these, (meth) acrylic resins, (meth) acrylic urethane resins, (meth) acrylic silicone resins, polyesters can be dried at a relatively low temperature to form a near-infrared shielding coating. It is preferably a fluororesin such as a modified resin such as a vinyl resin, a silicone resin, a silicone alkyd resin, a silicone urethane resin, a silicone polyester resin, or a silicone acrylic resin, a polyvinylidene fluoride, or a fluoroolefin vinyl ether polymer. Note that acrylic resins and methacrylic resins are also referred to as acrylic resins.

When forming the transparent resin layer in which the near-infrared absorbing pigment is dispersed, as a compound other than those described above, for example, one or more solvents, additives, and the like may be included. Such a solvent is not particularly limited, and examples thereof include aromatic solvents such as toluene and xylene; alcohol solvents such as iso-propyl alcohol, n-butyl alcohol, propylene glycol methyl ether, and dipropylene glycol methyl ether; Examples include ester solvents such as butyl acetate, ethyl acetate, and cellosolve acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and one or more organic solvents such as dimethylformamide.
In addition, as the additive, a conventionally known additive generally used in a resin composition for forming a film, a coating film, or the like can be used. For example, a leveling agent; inorganic fine particles such as colloidal silica and alumina sol; Antifoaming agent, anti-sagging agent, silane coupling agent, viscosity modifier, metal deactivator, peroxide decomposer, plasticizer, lubricant, rust preventive agent, organic and inorganic UV absorber, inorganic System heat ray absorbent, organic / inorganic flameproofing agent, antistatic agent and the like.
In order to improve the durability of the dye, a quencher or an antioxidant can be added.
Examples of such quenchers include metal complex materials, such as “MIR 101”, a product name manufactured by Midori Chemical Co., “EST 5”, a product name manufactured by Sumitomo Seika Co., Ltd.
Representative antioxidants include hindered amine compounds, hindered phenol compounds, phosphite compounds, and the like, and these can be used alone or in combination of two or more.

Examples of the method for applying the transparent resin layer in which the near infrared absorbing dye is dispersed include immersion, spraying, brush coating, curtain flow coating, gravure coating, roll coating, spin coating, blade coating, bar coating, reverse coating, and die coating. , Spray coating, electrostatic coating and the like. In these cases, the organic solvent described above can be appropriately mixed and applied to the near-infrared shielding resin composition.
The thickness of the transparent resin layer in which the near-infrared absorbing pigment is dispersed is not particularly limited as long as it is appropriately set depending on the intended use. For example, it is desired that the dry thickness is 1 to 50 μm, preferably 1 to 20 μm.

(Double-sided adhesive film for near-infrared shielding)
As a method for forming the near-infrared shielding double-sided pressure-sensitive adhesive film 1 of this embodiment shown in FIG. 1, a transparent resin layer in which a near-infrared reflecting agent 4a and a near-infrared absorbing dye 4b are dispersed on a transparent substrate 5 is used. A method of forming a laminated near-infrared shielding layer and laminating the adhesive layers 3 and 6 and the release films 2 and 8 made of a transparent resin on both sides of the near-infrared shielding layer in order.

  The near-infrared shielding double-sided pressure-sensitive adhesive film 1 of this embodiment shown in FIG. 1 peels and removes the release films 2 and 8 made of a transparent resin, whereby a near-infrared reflector 4a and a near-infrared reflector 4a The near-infrared shielding laminate 7 in which the pressure-sensitive adhesive layers 3 and 6 are provided on both surfaces of the laminate obtained by laminating the transparent resin layer in which the infrared absorbing dye 4b is dispersed can be obtained. Since this laminated body 7 has adhesiveness on both sides, a near-infrared shielding layer is obtained by bonding to a functional film such as an antireflection film or an antiglare film, an electromagnetic wave shielding film, an ultraviolet absorbing film, or a neon light cut film. It is possible to manufacture an optical filter for display having

An optical filter for display (hereinafter, simply referred to as an optical filter of the present invention) manufactured using the double-sided adhesive film 1 for shielding near infrared rays of the present invention shown in FIG. 1 is a front surface of a display such as a plasma display panel (PDP). It can be used by being directly attached to the panel P.
By incorporating the double-sided pressure-sensitive adhesive film 1 for shielding near infrared rays of the present invention as a near-infrared shielding layer constituting an optical filter, the near-infrared rays emitted from the display can be shielded.

  An optical filter 10 of an example shown in FIG. 2 includes, in order from the visual side (upper side in FIG. 2), an antireflection layer 11, a transparent substrate (ultraviolet absorption layer) 12 to which an ultraviolet absorber is added, an adhesive layer 13, A transparent resin layer (near infrared shielding layer) in which the near infrared reflector 4a and the near infrared absorbing dye 4b are dispersed, the transparent base material 15, the adhesive layer 16, the electromagnetic wave shielding material 19, and the transparent material that supports the electromagnetic wave shielding material 19 are supported. The substrate 20 and the pressure-sensitive adhesive layer 21 are laminated.

  In FIG. 2, an ultraviolet absorber is added to the transparent substrate 12 to form an ultraviolet absorbing layer, and the transparent substrate 12 supporting the antireflection layer 11 and the electromagnetic wave shielding material 19 are close to each other in the present invention. The release film made of the transparent resin on both sides constituting the double-sided adhesive film for infrared shielding is peeled off, and the adhesive is adhered to both sides of the laminate in which the transparent resin layer in which the near-infrared absorbing pigment is dispersed is laminated on the transparent substrate 15. Although the example which laminated | stacked the double-sided adhesive film layer 17 in which the agent layers 13 and 16 were laminated | stacked is shown, the combination of the layer employ | adopted as an optical filter among a near-infrared shielding layer, an ultraviolet absorption layer, a neon light absorption layer, and an antireflection layer, The order is not particularly limited to this.

  For example, like an optical filter 30 of another example shown in FIG. 3, in order from the visual side (upper side in FIG. 3), an antireflection layer 31, a transparent substrate (ultraviolet absorption layer) 32 to which an ultraviolet absorber is added, A transparent resin layer (near-infrared shielding layer) in which the pressure-sensitive adhesive layer 39, the electromagnetic wave shielding material 40, the support base 41 of the electromagnetic wave shielding material 40, the pressure-sensitive adhesive layer 33, the near-infrared reflecting agent 34a and the near-infrared absorbing dye 34b are dispersed; The transparent base material 35 and the adhesive layer 36 may be laminated. In this optical filter 30, the three layers of the pressure-sensitive adhesive layer 33, the near-infrared shielding layer (34a, 34b), the transparent substrate 35, and the pressure-sensitive adhesive layer 36 are peeled from the double-sided pressure-sensitive adhesive film for near-infrared shielding of the present invention. It can comprise using the double-sided adhesive film layer 37 obtained by peeling a film.

  In the optical filter, a transparent base material coated with a functional layer such as an antireflection layer, an ultraviolet absorption layer, or a neon light absorption layer can be laminated and exist in the layer structure of the filter. However, from the viewpoint of suppressing an increase in reflectivity by reducing the reflective interface, it is preferable to reduce the number of transparent base material layers as much as possible.

  2 and 3, as an example of the functional film, an antireflection film in which the antireflection layers 11 and 31 are provided on one side of the transparent base materials 12 and 32, and an electromagnetic wave shielding material on one side of the transparent base materials 20 and 41. An example in which an electromagnetic wave shielding film provided with 19 and 40 is used is shown. Other examples of the functional film that can be used in the optical filter of the present invention include an ultraviolet absorbing film and a neon light cut film.

The transparent material constituting the transparent base material 12, 15, 20, 32, 35, 41 of the optical filter is a plastic made of a resin that is transparent in the visible region, has flexibility, and preferably has good heat resistance. It is a film.
Examples of such plastic films include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), diacetate resins, triacetate resins, acrylic resins, polycarbonate resins, triacetyl cellulose, polystyrene, polyolefins, polyurethane resins. , A single layer or a composite film having a thickness of 10 to 600 μm made of polyvinyl chloride, polyimide resin, polyamide resin or the like.

  The pressure-sensitive adhesive constituting each pressure-sensitive adhesive layer 13, 16, 21, 33, 36, 39 of the optical filter is not particularly limited as long as it is transparent in the visible region (that is, has sufficient transmittance). The pressure-sensitive adhesive is the same as the pressure-sensitive adhesive used in the present invention, and an acrylic pressure-sensitive adhesive is preferably used from the viewpoint of transparency and weather resistance.

(Antireflection layer)
Here, the antireflection layers 11 and 31 are for preventing reflection of visible light from the outside of the optical filters 10 and 30. In the case of a single layer, the antireflection layers 11 and 31 are transparent substrates that support the antireflection layers 11 and 31. A thin film of a material having a lower refractive index than the materials 12 and 32, for example, a fluorine-containing organic compound having a polysiloxane structure is formed. In the case of multiple layers, a material having a higher refractive index than that of the transparent substrates 12 and 32, for example, a vapor-deposited thin film of titanium oxide, and a material having a lower refractive index than that of the transparent substrate, such as a thin film of silicon oxide, are alternately arranged. Laminate. The formation method of such a metal oxide thin film is not particularly limited, and a thin film of zirconium oxide, ITO, silicon oxide, or the like can be formed by a sputtering method, a vacuum evaporation method, or a wet coating method.

(UV absorbing layer)
If necessary, one or more ultraviolet absorbing layers can be provided at an appropriate position of the optical filter. As a method for forming the ultraviolet absorbing layer, a method in which an ultraviolet absorber is mixed into a transparent substrate or an adhesive layer, a coating solution containing an ultraviolet absorber is applied directly on the transparent substrate or through another layer. For example. The ultraviolet absorbing layer is provided closer to the visual side than the near infrared shielding layer in order to prevent the near infrared shielding layer from being deteriorated by external light. As the ultraviolet absorber, either an organic ultraviolet absorber or an inorganic ultraviolet absorber can be used, but the wavelength at 50% transmittance is preferably 350 to 420 nm, more preferably 360 to 400 nm. When the wavelength at the 50% transmittance is lower than 350 nm, the ultraviolet blocking ability is weak, and when the wavelength is higher than 420 nm, the coloring becomes strong.

  Examples of organic ultraviolet absorbers include 2- (2′-hydroxy-5′-t-butylphenyl) benzotriazole, 2- (2-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole, and the like. Benzotriazole compounds, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone and other benzophenone compounds, phenyl salicylate, 4-t-butylphenyl salicylate, 2,5 Hydroxybenzoate compounds such as -t-butyl-4-hydroxybenzoic acid n-hexadecyl ester and 2,4-di-t-butylphenyl-3 ', 5'-di-t-butyl-4'-hydroxybenzoate Etc. Examples of inorganic ultraviolet absorbers include titanium oxide, zinc oxide, cerium oxide, iron oxide, and barium sulfate. These ultraviolet absorbers can be used alone or in combination of two or more.

(Neon light absorption layer)
One or more neon light absorbing layers can be provided at an appropriate position of the optical filter as necessary. The neon light absorption layer is for making the red color of an image clearer by removing neon light (absorption wavelength: 580 to 620 nm) emitted from the PDP using a neon light absorber.

As a method of forming a neon light absorbing layer, a method of mixing a neon light absorber in a transparent substrate or an adhesive layer, a coating liquid containing a neon light absorber directly on a transparent substrate or other The method of apply | coating through a layer is mentioned. Examples of the neon light absorber include suitable dyes having a maximum absorption wavelength in a wavelength range of 580 to 620 nm among dyes such as cyanine, squarylium, azomethine, xanthene, oxonol, and azo. It is done. These neon light absorbers can be used alone or in combination of two or more.
If necessary, one or a combination of two or more dyes / pigments having absorption in the visible light region can be used for adjusting transmittance and color tone. As such a material, materials such as phthalocyanine, anthraquinone, quinoline, carbon black, and inorganic pigment can be used.

(Electromagnetic wave shielding material)
In the present invention, the electromagnetic shielding materials 19 and 40 made of a conductive metal mesh manufactured by a known method and the electromagnetic shielding material made of a transparent conductive film can be used. Since a plasma display generates a large amount of electromagnetic waves, an electromagnetic shielding material made of a metal mesh is preferable. Electromagnetic shielding material using conductive metal mesh is an etching method or thin wire that forms a conductive metal pattern by photolithography after laminating a metal foil on a transparent substrate or depositing a metal thin film on a transparent substrate. It is possible to use a pattern produced with developed silver produced by a photographic method and then using a photographic silver-plating method or the like that forms a conductive metal pattern by plating on this developed silver thin film. it can.

(Optical filter manufacturing method)
Although the manufacturing method of the optical filters 10 and 30 shown in FIG. 2 and FIG. 3 is not specifically limited, For example, the manufacturing method of the optical filter 10 shown in FIG. 2 can use the method shown below. In addition, in order to protect an adhesive layer during a manufacturing process or after a process, you may laminate | stack a peeling film arbitrarily.

(1) The electromagnetic shielding material 19 formed on the transparent base material 20 manufactured by a well-known method is prepared. In the present invention, an electromagnetic shielding material made of a conductive metal mesh or an electromagnetic shielding material made of a transparent conductive film can be used.
(2) The antireflection layer 11 is provided on one surface of the transparent substrate 12 to produce a laminate S1 (AR film).
(3) After forming a selective reflection layer A by laminating a solidified body of cholesteric liquid crystal polymer on one surface of the transparent substrate 15, a transparent resin layer in which a near-infrared absorbing dye is dispersed on the selective reflection layer A From the double-sided pressure-sensitive adhesive film for shielding near infrared rays according to the present invention, the pressure-sensitive adhesive layers 13 and 16 and a release film made of a transparent resin are sequentially laminated on both sides of the near-infrared shielding layer formed by laminating one release film. Is peeled off, and on the side of the pressure-sensitive adhesive layer 13 laminated on the near-infrared absorbing layer B made of a transparent resin layer in which the near-infrared absorbing pigment is dispersed, the side opposite to the surface on which the antireflection layer 11 of the laminate S1 is provided. The laminate S2 is manufactured by pasting on the surface.
That is, the selective reflection layer A is disposed on the side of the entire panel P close to the near infrared generation source.
(4) The other release film is peeled off from the laminate S2 and laminated on the electromagnetic wave shielding material 19 formed on the transparent substrate 20 on the pressure-sensitive adhesive layer 16 side.
(5) The pressure-sensitive adhesive layer 21 is further laminated on the support base material 20 of the electromagnetic wave shielding material 19 to obtain the optical filter 10 of this embodiment (see FIG. 2).

  In the present invention, on the both sides of the near-infrared shielding layer formed by laminating the selective reflection layer A and the near-infrared absorbing layer B made of a transparent resin layer in which the near-infrared absorbing pigment is dispersed on the transparent substrate 15, Since the double-sided pressure-sensitive adhesive film 17 for shielding near infrared rays according to the present invention in which the pressure-sensitive adhesive layers 13 and 16 and a release film made of a transparent resin are sequentially laminated is used, the pressure-sensitive adhesive is applied to one side of the transparent substrates 12 and 15. The process to perform can be omitted.

  A near-infrared shielding layer 102 is formed on a transparent substrate 101 according to the prior art (see FIG. 4) by manufacturing a display optical filter using the near-infrared shielding double-sided adhesive film of the present invention. Compared to the case where the produced near-infrared shielding filter 100 is prepared and directly bonded to the constituent layer of the optical filter, the selective reflection layer A composed of a polymer solidified layer having a cholesteric liquid crystal structure and the near-infrared absorbing dye (B) By using together, it can manufacture at low cost by reducing the mixing amount of the near-infrared absorbing dye B.

  In addition, the near-infrared shielding double-sided adhesive film of the present invention is a transparent resin that covers the outermost surface during the storage period from the manufacturing process until it is used by being bonded to various functional films as an optical filter. The release film made of 1 functions as a protective film, and has an effect of protecting the near-infrared absorbing layer made of a transparent resin layer in which the internal near-infrared absorbing pigment is dispersed.

  The present invention can be used as an optical filter incorporating a near-infrared shielding filter used for a display such as a plasma display (PDP).

It is typical sectional drawing which shows embodiment of the double-sided adhesive film for near-infrared shielding of this invention. It is typical sectional drawing which shows an example of the optical filter of this invention. It is typical sectional drawing which shows the other example of the optical filter of this invention. It is typical sectional drawing which shows the structure of the near-infrared shielding film using the near-infrared absorption pigment | dye in a prior art.

Explanation of symbols

P ... front panel, 1 ... double-sided adhesive film for shielding near infrared rays, 2, 8 ... release film as protective film for near infrared shielding filter, 3, 6, 13, 16, 21, 33, 36, 39 ... adhesive Layer, 4a, 14a, 34a ... polymer solidified layer having a cholesteric liquid crystal structure, 4b, 14b, 34b ... near infrared absorbing layer, 7, 17, 37 ... double-sided adhesive film layer, 5, 15, 35 ... transparent substrate (Support substrate for polymer solidified body layer) 10, 20, ... Optical filter for display (optical filter), 11, 31 ... Antireflection layer, 12, 32 ... Transparent substrate (ultraviolet absorbing layer), 19, 40 ... Electromagnetic wave shielding material, 20, 41 ... Transparent base material that is a support material for the electromagnetic wave shielding material, 100 ... Near-infrared shielding filter, 101 ... Transparent base material, 102 ... Near-infrared shielding layer.

Claims (7)

  From a selective reflection layer A made of a polymer solidified body layer having a cholesteric liquid crystal structure that transmits visible light and selectively reflects near infrared rays in a specific wavelength range, and a transparent resin layer in which a near infrared absorbing dye is dispersed. The near-infrared absorbing layer B is a double-sided pressure-sensitive adhesive for shielding near-infrared rays, which is formed by sequentially laminating a pressure-sensitive adhesive layer and a release film made of a transparent resin on both sides of a laminated near-infrared shielding layer. the film.   The near selective reflection layer according to claim 1, wherein the selective reflection layer A is formed by laminating a plurality of polymer solidified layers having a plurality of cholesteric liquid crystal structures having different spiral pitches on one surface of a transparent substrate. Double-sided adhesive film for infrared shielding.   The selective reflection layer A is formed by laminating one layer of a polymer solidified layer having a cholesteric liquid crystal structure having a helical pitch continuously changed in the thickness direction of the layer on one surface of a transparent substrate. The double-sided pressure-sensitive adhesive film for shielding near infrared rays according to claim 1.   4. The solidified polymer layer having a cholesteric liquid crystal structure selectively reflects either a left circularly polarized light component or a right circularly polarized light component in the near infrared band. The double-sided pressure-sensitive adhesive film for shielding near infrared rays according to 1.   The near-infrared absorbing dye comprises two types of an absorbing dye for a long wavelength and an absorbing dye for a short wavelength each having a maximum absorption capacity in different wavelength bands in an absorption wavelength band of 800 nm to 1100 nm. The double-sided pressure-sensitive adhesive film for shielding near infrared rays according to any one of claims 1 to 4.   The near-infrared absorbing dye for long wavelengths is one selected from diimonium salt compounds, and the near-infrared absorbing dye for short wavelengths is a phthalocyanine compound, cyanine compound, thiol nickel complex compound The double-sided pressure-sensitive adhesive film for shielding near-infrared rays according to claim 5, which is one or two or more types of pigments selected from among the above. The release film made of a transparent resin on both sides constituting the double-sided pressure-sensitive adhesive film for shielding near infrared rays according to any one of claims 1 to 6, is peeled off, and an antireflection film or an antiglare film, an electromagnetic wave shielding film, an ultraviolet absorption film, And an optical filter for PDP that is bonded to one or more functional films selected from neon light cut films.

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