JP2002214427A - Nir absorbing composition, absorbing film and method for preparing the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an NIR absorbing composition which efficiently absorbs heat rays emitted from a plasma display, particularly IR in the near infrared region(NIR), ensures a very low degree of heat deterioration and a very low degree of cracking and is stable with age and to provide an NIR absorbing film using the composition at a low cost. SOLUTION: The NIR absorbing composition contains 100 pts.wt. polyacrylic ester or acrylic ester copolymer and 0.1-10 pts.wt. organic IR absorbent as essential components in such a way that the elongation percentage of a coating of the composition after fracture at 80-100 deg.C is made higher than the heat shrinkage percentage. The acrylic ester copolymer is preferably a copolymer of acrylamide and at least one other acrylic ester.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for shielding near infrared rays generated from a plasma display, an NIR absorbing film using the same, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a method of imparting an infrared absorbing property, a method of mixing a material having an infrared absorbing property into a resin and extruding the resin with the resin, and a method of mixing a resin / infrared absorbing composition with a solvent are used. And a thin film forming method using a vapor phase method such as vacuum evaporation or sputtering.

[0003]

However, in the extrusion molding method, there is a problem that the infrared absorbing agent is thermally deteriorated in the molding process because it is exposed to a high processing temperature.
In order to prevent the infrared absorbent from deteriorating during the production process, a specific resin composition is used as a so-called “binder” for the infrared absorbent “particles” to protect the infrared absorbent. It is also possible to some extent to suppress the progress of deterioration accompanying the process. However, even in such a case, when a film is formed using the manufactured infrared-absorbing composition, in a use environment where the film is exposed to high temperatures such as an EMI shield of a plasma display, appearance defects such as cracks occur in the film. It was easy. Furthermore, in the vapor phase thin film method, the equipment is large and the investment cost is high, and it is necessary to laminate a plurality of materials from several layers, and in some cases, ten or more layers in order to express desired infrared absorption. For this reason, it is currently not cost-competitive.

[0004] In view of the problems of the prior art, the present invention efficiently absorbs heat rays emitted from a plasma display, particularly infrared rays in the near infrared region (NIR), and causes the degree of thermal degradation and the generation of cracks. It is intended to supply an NIR-absorbing composition having an extremely small degree and stable over time and an NIR-absorbing film using the composition at low cost.

[0005]

According to the present invention, there is provided (a) 100 parts by weight of a polyacrylate or acrylate copolymer material having a breaking elongation at 80 to 100 ° C. which is larger than a heat shrinkage when formed into a film. And (b) 0.1 to 10 parts by weight of an organic infrared absorbing agent, which is an NIR absorbing composition used for a front panel of a plasma display.

An NIR-absorbing film applied to the front surface of a glass panel of a plasma display is firstly exposed to a high temperature for a long time at the bonding interface with the panel surface, and changes in temperature during temperature rise / fall. Even under the use environment, it should be able to maintain strong and stable adhesiveness at each point, (2) having appropriate thermodynamic properties as a whole film so as not to cause cracks such as cracks, Furthermore, (3) mechanical properties such as abrasion resistance and scratch resistance, (4)
It is also desired that the resin be chemically stable under the use environment, such as coloring, fading, and denaturation of the resin.

The present inventors have investigated NIR absorbing film materials, in particular, infrared absorbing films as an additional function of an EMI shielding film for a plasma display.
I have been working hard. As a result, in order to prevent cracks from occurring in the applied film-forming composition under the above-mentioned use conditions with temperature changes, the competition between mechanical and thermodynamic properties, that is, plasma The film must be configured so that the film has a breaking elongation greater than the heat shrinkage under high-temperature use conditions (80 to 100 ° C., which has more room for test temperature, is generally adopted) on the front surface of the display. We recognize that it is very important.

When an NIR absorbing film is used for shielding near infrared rays generated from the front surface of a plasma display, the temperature of the plasma display generally rises to 80 ° C. or higher, and under such conditions, the film may not be covered. Causes minute cracks. Although these minute cracks are rarely observed with the naked eye, they are particularly important in such plasma display applications, because they are irregularly reflected when placed on the front of the display, resulting in a distinctly poor appearance.
As described above, the present inventors, even under such a use environment, if the elongation at break of the film is configured to be larger than the heat shrinkage, the film withstands thermal expansion and shrinkage,
I got the idea that the generation of micro cracks could be suppressed as much as possible, and based on this, actually conducted various tests,
With experimental support, the present invention has been completed.

As exemplified in the Examples, in order to obtain a polymer / infrared absorber composition having such a mechanical / thermodynamic property relationship, specifically, Acrylamide as a part of the monomer during production,
It is preferable to use an acrylamide / acrylic ester copolymer obtained by using an appropriate amount.

As the organic infrared absorber, an aminium compound, a diimonium compound, a nickel dithiol compound, or a mixture thereof is desirable.

It is further desirable that the elastic modulus of the polyacrylate or acrylate copolymer material is 0.1 GPa or more at 80 ° C. to 100 ° C.

The present invention also provides a NIR having a layer of the NIR absorbing composition as described above on a plastic film.
An absorbent film, wherein the plastic film is 6
It is desirable to have a visible light transmittance of 0% or more, and typically EMI applied to the surface of a plasma display panel
It constitutes a shield film.

[0013] The present invention also provides a plastic film,
A first layer laminated on the plastic film;
A NIR absorption laminate for use in a front panel portion of a plasma display, comprising a second layer laminated on a layer, wherein the first layer comprises the following (A) and the second layer comprises the following (B) Or the first layer comprises the following (B) and the second layer comprises the following (A).

(A) The above-mentioned NIR absorbing composition (B) A resin having an elastic modulus at 80 ° C. smaller than that of the polyacrylate or acrylate copolymer constituting the above (A). a) 100 parts by weight of an acrylate copolymer and (b) an organic infrared absorbent 0.1 to 1
A method for producing an NIR-absorbing composition for use in a front panel part of a plasma display, comprising 0 parts by weight as an essential component. 80 ° C. when the composition is formed into a film by polymerizing the polymer (a)
The above-mentioned production method, wherein the elongation at break at -100 ° C is larger than the heat shrinkage. In the above method, it is further desirable to use the acrylamide and adjust the amount of the acrylamide so that the modulus of elasticity of the copolymer (a) at 80 to 100 ° C. is 0.1 GPa or more.

In the present application, “elongation at break”
The term "heat shrinkage" is used, and these definitions are as given in JIS K-7113 and K-7197, respectively.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, usable polyacrylates include polyethyl acrylate, polybutyl acrylate, poly-2-ethylhexyl acrylate, poly-t-butyl acrylate, poly-3-ethoxypropyl acrylate, and polyoxycarbonyl. Tetramethacrylate, polymethylacrylate, polyisopropylmethacrylate, polydodecylmethacrylate, polytetradecylmethacrylate, poly-n-propylmethacrylate, poly-3,3,5-trimethylcyclohexylmethacrylate, polyethylmethacrylate, poly-2-nitro-2 Poly (meth) acrylates such as -methylpropyl methacrylate, poly-1,1-diethylpropyl methacrylate and polymethyl methacrylate are used It is a function. If necessary, two or more of these acrylic polymers may be copolymerized, or two or more of them may be used as a blend.

Further, epoxy acrylate, urethane acrylate, polyether acrylate, polyester acrylate and the like can also be used as the copolymer resin of acrylic resin and other than acrylic resin. In particular, urethane acrylate, epoxy acrylate, and polyether acrylate are excellent from the viewpoint of adhesiveness. Examples of epoxy acrylate include 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, allyl alcohol diglycidyl ether,
(Meta) such as resorcinol diglycidyl ether, diglycidyl adipic ester, diglycidyl phthalate, polyethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether, sorbitol tetraglycidyl ether, etc. Acrylic acid adducts are mentioned. These copolymer resins can be used in combination of two or more as necessary.

The heat shrinkage of the produced resin film at 80 to 100 ° C. is typically 2 to 5%. Therefore, the elongation at break is understood to be 5% or more. More preferably, it is 10% or more.

The present inventors have found that the NIR
We have studied thin film properties suitable as an absorbing film. According to this, it is desirable that the elastic modulus of the polymer at 80 ° C to 100 ° C is designed to be 0.1 GPa or more.
If the elastic modulus is less than 0.1 GPa, the fluidity of the resin composition formed into a film increases, and the temporal stability of the infrared absorbent decreases. It seems particularly desirable to be about 0.3 GPa.

The resin composition used in the present invention may further contain additives such as a diluent, a plasticizer, an antioxidant, an ultraviolet absorber, a filler, a tackifier, and a crosslinking agent, if necessary. May be.

As the infrared absorber used in the present invention, an aminium compound, a diimonium compound (trade name, manufactured by Nippon Kayaku Co., Ltd.) or a nickel dithiol (SIR-
128, SIR-130, SIR-132, SIR-1
Organic IR absorbers such as No. 59, SIR-152, SIR-162) and (these are trade names of Mitsui Chemicals, Inc.), and these can be contained in the resin. Among these infrared absorbing compounds, the diimonium compound infrared absorbing agent has the most effective effect of absorbing infrared light. In the case of infrared absorbers other than organic infrared absorbers, attention must be paid to the particle size of the primary particles of these compounds. If the particle size is too large than the wavelength of infrared rays, the shielding efficiency is improved, but irregular reflection occurs on the particle surface and haze is increased, so that transparency is reduced. On the other hand, if the particle size is too short compared to the wavelength of infrared rays, the shielding effect will be reduced. The preferred particle size is 0.01 to 5 μm, more preferably 0.1 to 3 μm.

The infrared absorbing agent, which is an infrared absorbing material, is uniformly dispersed in the polyacrylate. The optimal amount of the compound is polyacrylate 10
The infrared absorber is 0.1 to 10 parts by weight with respect to 0 parts by weight. If the amount is less than 0.1 part by weight, the infrared absorbing effect is insufficient.
Exceeding 0 parts by weight makes it difficult to achieve a sufficient miscibility with the resin, which is not preferred.

The composition containing the above-mentioned infrared absorbent in a polyacrylate is diluted with one or more solvents selected from acetone, MEK, acetonitrile and the like, and then formed on one surface of a transparent film. . Alternatively, the infrared absorbing agent may be first diluted with these solvents and then mixed with the polyacrylate. At this time, the pH of these compositions is preferably in the range of 4.0 to 8.0, and if the pH value deviates from this range, the temporal stability of the NIR absorbing film may decrease. Further, when the film is formed, the amount of the remaining solvent is 10% or less, and when the amount is 5% or less, the stability over time of NIR absorbability is increased. A film of the composition containing the infrared absorbing agent thus obtained is formed on the first layer of the plastic film, and the second layer thereon has a polyacrylic modulus of 80% at the first layer. A resin layer smaller than an acid ester may be formed. Alternatively, it is also possible to form a film of a resin layer having an elastic modulus at 80 ° C. smaller than the second layer on the first layer of the transparent film and form the composition on the second layer. At that time, at least one layer containing the infrared absorber is required, and the other layers may not contain the infrared absorber. Examples of the resin having such a low elastic modulus include, in addition to the above-mentioned polyacrylate, natural rubber, isoprene rubber, chloroprene rubber, polyisobutylene, butyl rubber, butyl halide, acrylonitrile-butadiene rubber, styrene-
Butadiene rubber, polyisobutene, carboxy rubber, neoprene, polybutadiene, aniline formaldehyde resin, urea formaldehyde resin, phenol formaldehyde resin, ligulin resin, xylene formaldehyde resin, xylene formaldehyde resin, melamine formaldehyde resin, epoxy resin, urea resin, aniline resin, melamine resin Phenolic resin, formalin resin, metal oxide, metal chloride, oxime, alkylphenol resin and the like. In addition, poly-1,2-
Butadiene, polybutene, poly-2-heptyl-1,3
(Di) enes such as butadiene, poly-2-t-butyl-1,3-butadiene and poly-1,3-butadiene;
Polyethers such as polyoxyethylene, polyoxypropylene, polyvinyl ethyl ether, polyvinyl hexyl ether, and polyvinyl butyl ether; polyesters such as polyvinyl acetate and polyvinyl propionate; polyurethane, ethyl cellulose, polyvinyl chloride, polyacrylonitrile, and polymethacryloyl Nitriles, polysulfones, polysulfides, phenoxy resins and the like can be used. If necessary, two or more of these polymers may be copolymerized, or two or more of them may be used as a blend. These compositions are applied in a thickness of 0.1 to 100 μm on a transparent film. The applied composition containing an infrared absorbing compound may be cured using heat or ultraviolet light.

Hereinafter, the present invention will be described in detail with reference to examples.

[0026]

Example 1 In a three-necked flask equipped with a 500 cm ³ thermometer, a cooling tube and a nitrogen inlet tube, 200 cm ³ of toluene, 50 g of methyl methacrylate (MMA), 5 g of ethyl methacrylate (EMA), and 2 g of acrylamide (AM) , AIB
Add 250 mg of N and bubbling with nitrogen
Stirring was performed at reflux for 3 hours. Thereafter, the precipitate was reprecipitated with methanol, and the obtained polymer was filtered and dried under reduced pressure to synthesize a polyacrylate. The elastic modulus at 80 ° C. of the polymer was 1.2 GPa. This was used as the main component of the resin layer 1.

<Composition of Resin Layer 1> Polyacrylate (MMA / EMA / AM = 88)
/ 9/3) 100 parts by weight SIR-159 (infrared absorbent: trade name of Mitsui Toatsu Chemicals, Inc.) 0.5 part by weight MEK 230 parts by weight Acetone 10 parts by weight 80 ° C. after drying the above resin composition in a solvent The heat shrinkage of the film was 2.5%, and the elongation at break was 7%.

Next, methyl methacrylate (MMA) 50 was prepared in the same manner as in the above polyacrylate synthesis procedure.
g, 5 g of ethyl methacrylate (EMA), 3 g of butyl methacrylate (BMA), and 225 mg of AIBN, and the mixture was stirred under reflux at 100 ° C. for 2.5 hours while bubbling with nitrogen. Thereafter, the precipitate was reprecipitated with methanol, and the obtained polymer was filtered and dried under reduced pressure to synthesize a polyacrylate. The elastic modulus at 80 ° C. of the polymer was 0.6 GPa. This was used as the main component of the resin layer 2.

<Composition of Resin Layer 2> Polyacrylate (MMA / EMA / BMA = 8)
6/9/5) 100 parts by weight MEK 230 parts by weight The resin layer 1 thus obtained is applied on a PET film (manufactured by Toyobo Co., Ltd., trade name A-4100, film thickness 50 μm) after drying. It was applied to a thickness of 15 μm. Thereafter, the resin layer 2 was applied on the resin layer 1 so that the dry coating thickness became 10 μm, thereby producing an NIR absorption film.

[0030]

Embodiment 2 As an infrared absorber in the resin layer 1, SIR-
A resin layer 3 was prepared in the same manner as in Example 1 except that 1.0 part by weight of NIR-022 (trade name, manufactured by Nippon Kayaku Co., Ltd.) was added instead of 159. The elastic modulus of the polymer at 80 ° C. was 1.2 GPa, the heat shrinkage of the film at 80 ° C. after drying the solvent of the resin composition was 2.2%, and the elongation at break was 9%. The resin layer 2 obtained in Example 1 was coated on a PET film (manufactured by Toyobo Co., Ltd., trade name: A-4100, film thickness: 50 μm).
Coating was performed so that the coating thickness after drying was 5 μm. Thereafter, the resin layer 3 of the present embodiment is coated on the resin layer 2 with a dry coating thickness of 2.
It was applied so as to have a thickness of 0 μm to prepare an NIR absorption film.

[0031]

Comparative Example 1 In the same manner as in Example 1, a polyacrylic ester as a main component of the resin layer 1 was synthesized. However, the composition is MMA / AN (acrylonitrile) = 95/5
And The elongation at break of this polymer at 80 ° C. was 2.5%, the shrinkage upon heating was 4%, and the elastic modulus at 80 ° C. was 0.8 GPa. Using this resin layer 1, an NIR absorption film was produced in the same manner as in Example 1.

[0032]

Comparative Example 2 In the same manner as in Example 1, a polyacrylic ester as a main component of the resin layer 1 was synthesized. However, the composition was MMA / MAA (methacrylic acid) = 81/19
And The elongation at break of this polymer at 80 ° C. was 3.5%, the heat shrinkage was 5%, and the elastic modulus at 80 ° C. was 1.1 GPa. Using this resin layer 1, an NIR absorption film was produced in the same manner as in Example 1.

Table 1 summarizes the results of an investigation on the degree of cracking, NIR absorption, and stability over time of the NIR absorbing film produced as described above.

The occurrence of cracks was caused by the NIR absorption film
After standing at 0 ° C. for 500 hours, the degree was visually observed. The elastic modulus was measured using a viscoelasticity measuring device RSA-II manufactured by Rheometric Scientific F.E.
The storage modulus at 80 ° C. was employed. The NIR absorption characteristics were measured by using a spectrophotometer V-570 manufactured by JASCO Corporation, and exposing the NIR
The simple average transmittance in the 850-1100 nm region of the IR film was used. The aging stability is as follows.
The change in color after exposure to 90% RH for 1000 hours was visually confirmed, and the degree of the change was expressed by a large to small relative evaluation.

[0035]

[Table 1]

[0036]

As will be understood from the results of the above examples, the NIR absorbing film according to the present invention has a very small degree of crack generation and has a long-term stability of near-infrared absorption characteristics in a wavelength range of 850 to 1100 nm. And little change in heating and humidification tests, and excellent in stability over time.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 5/32 C09D 5/32 133/06 133/06 C09K 3/00 105 C09K 3/00 105 G09F 9 / 00 313 G09F 9/00 313 // C08L 67:02 C08L 67:02 (72) Inventor Minoru Tosaka 1500 Oji Ogawa, Shimodate-shi, Ibaraki Prefecture F-term in Hitachi Chemical Industry Research Laboratory 2H048 CA04 CA05 CA12 4F006 AA35 AB24 AB55 BA03 CA05 4F100 AK01A AK01C AK25B AK25J AK26B AK26J AK42 AL01B BA02 BA03 CA07B EH462 GB41 JA03B JD10 JK07B JK07C JK08B JK14 JL02 JM02B JN08 4J011 CG141 A0311

Claims (10)

[Claims] 1. An NIR absorbing composition for use in a front panel of a plasma display, comprising the following components (a) and (b) as essential components: (a) 100 parts by weight of a polyacrylate or acrylate copolymer material whose elongation at break at 80 to 100 ° C. when formed into a film is larger than the heat shrinkage (b) Organic infrared absorber 0.1 to 10 Parts by weight 2. The NIR absorbing composition according to claim 1, wherein the organic infrared absorbing agent is an infrared absorbing agent selected from the group consisting of an aminium compound, a diimonium compound, a nickel dithiol compound, and a mixture thereof. . 3. An elastic modulus of the polyacrylate or acrylate copolymer material is 80 ° C. to 100 ° C.
The N according to claim 1, which is 0.1 GPa or more.
IR absorbing composition. 4. The NIR absorbing composition according to claim 1, wherein the acrylate ester copolymer is a copolymer of acrylamide and at least one other acrylate ester. 5. An NIR absorbing film having a layer of the NIR absorbing composition according to claim 1 on a plastic film. 6. The NIR absorbing film according to claim 5, wherein the plastic film has a visible light transmittance of 60% or more. 7. The NIR absorbing film according to claim 5, which constitutes an EMI shielding film attached to the surface of the plasma display panel. 8. An NIR absorber for use in a front panel of a plasma display, comprising: a plastic film; a first layer laminated on the plastic film; and a second layer laminated on the one layer. A laminate,
Wherein the first layer comprises the following (A) and the second layer comprises the following (B), or the first layer comprises the following (B) and the second layer comprises the following (A): NIR absorbing laminate. (A) the NIR absorbing composition according to any one of claims 1 to 3 (B) a resin having an elastic modulus at 80 ° C smaller than that of the polyacrylate or acrylate copolymer material constituting (A). 9. (a) Acrylate copolymer 10
A method for producing an NIR-absorbing composition for use in a front panel of a plasma display, comprising, as essential components, 0 parts by weight and (b) 0.1 to 10 parts by weight of an organic infrared absorbent. By using acrylamide for the part and adjusting the addition amount thereof to polymerize the copolymer (a), the composition is formed into a film at 80 ° C to 100 ° C.
The manufacturing method according to the above, wherein the elongation at break in the above is larger than the heat shrinkage. 10. The copolymer (a) having a molecular weight of 80 to
The production method according to claim 9, wherein the acrylamide is used and its amount added is adjusted so that the elastic modulus at 100 ° C is 0.1 GPa or more.