JP2008038069A - Binder resin for near-infrared-absorbing film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a binder resin for near-infrared-absorbing film, high in flexibility, highly adhesive even under moist heat without causing debonding and foaming, and also stably containing a near-infrared light absorber. <P>SOLUTION: The binder resin for near-infrared-absorbing film is obtained by copolymerization between (A) 10-30 mass% of lauryl methacrylate and/or 2-ethylhexyl methacrylate, (B) 1-10 mass% of methacrylic acid, (C) 50-88 mass% of methyl methacrylate and (D) 1-60 mass% of a cycloolefin ring-containing monomer. This binder resin has a Tg of -10 to 70°C and a weight-average molecular weight of 200,000-500,000. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a binder resin for a near-infrared absorbing film. More specifically, the present invention relates to a near-infrared absorbing film that absorbs near-infrared light by sticking it to the surface of a device that emits near-infrared light such as a plasma display panel or glass of a building. The present invention relates to a near-infrared absorbing film binder resin used.

  In recent years, plasma display panels and thin televisions using liquid crystal panels are becoming popular. Among them, the plasma display panel is advantageously used for a large thin television, but this has a problem of emitting near infrared rays (hereinafter referred to as “NIR”) as unnecessary radiation, such as a TV remote control. There was a problem of causing malfunction of peripheral equipment.

  In order to effectively shield this NIR and transmit only visible light, a near-infrared absorbing film (NIR film) is used. This NIR film is obtained by uniformly dispersing a NIR absorbent such as a pigment in a matrix resin and coating it on a transparent plastic film, but has the following problems.

  That is, when a NIR film matrix resin having high transparency such as polyester and methacryl and having high dye stability is used, it has a high glass transition temperature (Tg) and poor flexibility. For this reason, there is a drawback that a problem of cracks and adhesion to the substrate (floating, peeling) occurs. Moreover, since it was necessary to make multilayer as a functional film, there also existed a problem that it was necessary to laminate | stack an adhesive material layer further.

  On the other hand, a low Tg binder resin that is highly flexible and does not require lamination of an adhesive layer was used, and NIR dyes were also added to the adhesive layer, but the dye stability deteriorated and near infrared absorption There was a problem that the performance was lowered and the resin was colored.

  Recently, several binder resins having good dye durability have been reported. For example, as a binder resin for an NIR film that has little dye fading and has suppressed foaming, white turbidity, and peeling upon wet heat, a copolymer of a (meth) acrylic monomer and an alicyclic structure-containing monomer has been reported (patent) Reference 1). However, since the dye concentration in the examples of this document is low and the evaluation temperature is as low as 60 ° C., it is considered that sufficient performance is not obtained.

  Moreover, in the Example of patent document 2, as a binder resin for NIR films with high dye stability and good substrate adhesion, an acrylic copolymer obtained by copolymerizing a (meth) acrylic monomer and an alicyclic structure-containing monomer. A blend of MMA homopolymer with the polymer is described. However, as confirmed by the present inventors, as in Patent Document 1, this also has insufficient dye stability and substrate adhesion.

  Furthermore, a binder resin for NIR film obtained by copolymerizing 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate and cyclohexyl methacrylate is also disclosed in Synthesis Example 1 of Patent Document 3. However, since this has a small number average molecular weight of 5,800, it is judged that the function of increasing the color fading of the dye, which is an NIR absorbent, is weak.

  Furthermore, Patent Document 4 exemplifies lauryl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid, methyl methacrylate, cyclohexyl methacrylate and the like as constituent monomers of the binder resin for NIR film. However, this contains a fluorinated polymer as an essential component, and if no fluorinated polymer is contained, problems such as cracks and changes in the color of the coating film may occur. 2.

JP2004-182793 JP2005-239999 JP 2002-249721 JP 2004-115718 A

  Accordingly, the object of the present invention is to provide a binder resin for NIR that is highly flexible, has good adhesion even in wet heat, does not peel off or foam, prevents discoloration of the NIR absorbent, and can be stably contained. Is to provide.

  In order to solve the above-mentioned problems, the present inventors have blended various polymers and searched for their adhesion and fading suppression action under various wet heat conditions for various NIR absorbing dyes. The (meth) acrylic copolymer obtained by copolymerizing the monomers is excellent in adhesion and flexibility, and does not peel or bulge from the substrate even under hot and humid conditions. The present invention was completed.

That is, the present invention provides the following monomers (A) to (D)
(A) Lauryl methacrylate and / or 2-ethylhexyl methacrylate 10-30% by mass
(B) Methacrylic acid 1 to 10% by mass
(C) Methyl methacrylate 50-88 mass%
(D) Cycloolefin ring-containing monomer 1 to 30% by mass
Is a binder resin for NIR film having a Tg of 10 to 70 ° C. and a weight average molecular weight of 200,000 to 500,000.

  Since the binder resin for NIR film of the present invention has a low Tg with a specific monomer composition, it has good adhesion even in wet heat and does not peel off or foam even though the Tg is relatively low. In addition, the color fading resistance of the dye is also good.

The binder resin for NIR film of the present invention is obtained by copolymerizing the following monomers (A) to (D) according to a conventional method, and has a Tg of 10 to 70 ° C. and a weight average molecular weight of 200,000 to 500,000. .
(A) Lauryl methacrylate and / or 2-ethylhexyl methacrylate 10-30% by mass
(B) Methacrylic acid 1 to 10% by mass
(C) Methyl methacrylate 50-88 mass%
(D) Cycloolefin ring-containing monomer 1 to 30% by mass

  Among the above monomers, the monomer (A) has an effect of increasing flexibility as the Tg of the copolymer is lowered. As this monomer (A), lauryl methacrylate or 2-ethylhexyl methacrylate may be used alone or in combination. By using these monomers (A), while improving the flexibility of the resulting copolymer, it is possible to increase the adhesion to the substrate and to maintain a stable dye. A similar effect cannot be obtained even when 2-ethylhexyl acrylate is replaced with a monomer similar to the above, for example, 2-ethylhexyl methacrylate.

  In addition, the monomer (B) has a function of enhancing the flexibility of the copolymer and strengthening adhesion to a film substrate such as PET, and the monomer (C) is a main component of the binder resin. It will be.

  Furthermore, the cycloolefin ring-containing monomer as the monomer (D) functions to increase the polarity of the copolymer and increase the adhesion. Examples of this monomer (D) include dicyclopentanyl methacrylate, cyclohexyl methacrylate, methyl cyclohexyl methacrylate, cyclododecyl methacrylate, t-butyl cyclohexyl methacrylate, isobutyl cyclohexyl methacrylate and the like.

  The production of the copolymer obtained from the monomer (A) to (D) of the present invention (hereinafter referred to as “the polymer of the present invention”) can be carried out by a known method. That is, the monomer (A) to (D) in the above amount and, if necessary, other polymerizable components are taken into the reactor, and then polymerized by light or heat. As a polymerization method for obtaining the polymer of the present invention, known polymerization methods such as solution polymerization, suspension polymerization, emulsion polymerization, dispersion polymerization, bulk polymerization and the like are used, and among these, solution polymerization is preferable.

  The reaction initiator used in the above method includes thermal polymerization initiators such as peroxide initiators and azo initiators, and photopolymerization initiation such as acetophenone initiators, benzoin ether initiators, and ketal initiators. Agents can be used.

  More specifically, examples of the thermal polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di- sec-butyl peroxydicarbonate, t-butylperoxybenzoate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n- Octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di (4-methylbenzoyl) peroxide, 1,1-di (t-hexylperoxy) cyclohexane, di Benzoyl peroxide (BPO), 1,1-bis (t-butylperoxy) , 3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclododecane, t-butylperoxyisobutyrate, t-butylhydroperoxide, di-t-butylhydroperoxide, dicumyl Peroxide initiators such as peroxide and hydrogen peroxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2 '-Azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 1,1-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (2 , 4,4-trimethylpentane), dimethyl 2,2′-azobis (2-methylpropionate), 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azo [2- (5-Methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (N, N ′) -Dimethyleneisobutylamidine), 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate, and other azo initiators.

  Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α'-dimethylacetophenone, methoxyacetophenone, and 2,2-dimethoxy. Acetophenone initiators such as 2-phenylacetophenone; benzoin ether initiators such as benzoin ethyl ether and benzoin isopropyl ether; ketal initiators such as benzyldimethyl ketal; bis (2,6-dimethoxybenzoyl) -2,4 , 4-trimethylpentylphosphine oxide, halogenated ketone, acyl phosphenoxide, acyl phosphenate and the like.

  In the present invention, among the above, it is preferable to use an oil-soluble thermal polymerization initiator, especially an azo-based initiator.

  Furthermore, the polymer of the present invention can be crosslinked within a range that does not impair the effects of the invention. As a crosslinking method, a method in which a polyfunctional monomer having two or more unsaturated bonds in one molecule is copolymerized, a monomer having reactivity with a crosslinking agent is copolymerized in a binder resin, an isocyanate-based crosslinking agent, an epoxy-based monomer Although there is a method of adding a crosslinking agent such as a crosslinking agent, it is not preferable to use a large amount of polyfunctional monomer or crosslinking agent because the flexibility of the resin may be lost or the viscosity of the resin may become too high. Moreover, since there is a possibility that the functional group having reactivity with the crosslinking agent or the reactor of the crosslinking agent may cause the near-infrared absorbing dye to fade, it is not preferable to use a large amount.

  In the production of the polymer of the present invention, the polymerizable components that can be incorporated into the monomers (A) to (D) as necessary include methyl acrylate, ethyl (meth) acrylate (meth) acrylate, and n-butyl (meta ) Acrylate (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, Nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, amyl (meth) acrylate, n-lauryl acrylate, stearyl (meth) acrylate, etc. (Meth) acrylate; alkoxy (meth) acrylate such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate; butoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) Alkoxyethylene glycol (meth) acrylates such as acrylate; Monomers containing carboxyl groups such as acrylic acid, β-carboxyethyl (meth) acrylate, crotonic acid, itaconic acid, fumaric acid, maleic acid; dimethylaminoethyl (meth) acrylate , Monomers containing amino groups such as diethylaminoethyl (meth) acrylate; monomers containing amide groups such as (meth) acrylamide and dimethyl (meth) acrylamide; 2-hydro Monomers having a hydroxyl group such as xylethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; vinyl acetate, acrylonitrile and the like. Among these, it is possible to use alkyl (meth) acrylates and alkoxy (meth) acrylates having good copolymerizability and compatibility with the monomers (A) to (D), and good stability of the near-infrared absorbing dye. preferable.

  Other monomers can be used as long as the effects of the present invention are not impaired, but are preferably used in the range of 0 to 10 parts by weight with respect to 100 parts by weight of the monomers (A) to (D). Of the above-mentioned other monomers, the functional group-containing monomer may cause discoloration of the near-infrared absorbing dye and has poor compatibility with the monomers (A) to (D) such as vinyl acetate and acrylonitrile. Since the monomer may cause whitening or peeling during wet heat, it is preferably used in a proportion of 5 parts by weight or less, and more preferably 1 part by weight or less.

  Among the polymers of the present invention thus obtained, those having a Tg of −10 to 70 ° C., preferably 20 to 70 ° C., and a weight average molecular weight of 200,000 to 500,000, preferably 200,000 to 400,000 are NIRs of the present invention. It can be used as a binder resin for film.

  If the polymer Tg is less than -10 ° C, the fading of the dye may not be sufficiently suppressed, and if it exceeds 70 ° C, flexibility may be lost and cracks may occur. It is not preferable as a binder resin. Further, when the weight average molecular weight is less than 200,000, the adhesion to the substrate may be deteriorated or the workability may be deteriorated. On the other hand, when the weight average molecular weight exceeds 500,000, the viscosity becomes high and a coating line is generated. In some cases, both are not preferred as binder resins for NIR films.

  In order to make Tg within the above range, monomers (B) to (D) having a relatively high homopolymer Tg and monomers (A) having a relatively low homopolymer Tg are used in the above-mentioned amount range. The binder resin of the present invention may be copolymerized with lauryl methacrylate and / or 2-ethylhexyl methacrylate as monomers (A) to form a binder resin. The dye can be stably held while imparting flexibility and substrate adhesion. In order to make the weight average molecular weight within the above range, the polymerization temperature, the initiator amount, the monomer concentration, etc. may be controlled.

  One of the preferred constitutional examples of the binder resin for NIR film of the present invention obtained as described above is as follows.

A polymer obtained by copolymerizing the following monomers (a) to (d) and having a Tg of about 69 ° C. and a Mw of about 220,000.
(A) Lauryl methacrylate 13% by mass
(B) Methacrylic acid 1% by mass
(C) Methyl methacrylate 76% by mass
(D) Dicyclopentanyl methacrylate 5% by mass
Cyclohexyl methacrylate 5% by mass

  The binder resin for NIR film of the present invention thus obtained is, for example, dissolved or suspended in a suitable organic solvent, mixed with an NIR absorbent, etc., then coated on a support film and dried. An NIR film can be prepared by removing the organic solvent.

  Examples of the NIR absorber used by mixing with the binder resin of the present invention include NIR absorbing dyes having an absorption maximum wavelength at 800 to 1200 nm, and specifically include phthalocyanine dyes, diimmonium dyes, dithiol metal complexes. And system dyes, naphthalocyanine dyes, anthraquinone dyes, and the like. Among them, it is preferable to use a diimmonium dye having high near infrared absorption performance and high transmittance in the visible light region. The diimmonium-based dye is a dye that is very easy to cause dye fading. However, when it is dispersed in the binder of the present invention, fading can be suppressed.

（式中、Ｒは互いに同一もしくは異なって、水素、アルキル基、アリール基、アルコキシ基、ヒドロキシル基、フェニル基もしくはハロゲン化アルキル基を示し、Ｘは陰イオンを示す。ｎは１又は２の数である） As the above diimonium dye, it is preferable to use a compound represented by the following formula (I) having an absorption maximum wavelength at 850 to 1200 nm.

Wherein R is the same or different from each other, and represents hydrogen, an alkyl group, an aryl group, an alkoxy group, a hydroxyl group, a phenyl group or a halogenated alkyl group, X represents an anion, and n is a number of 1 or 2. Is)

  In the above formula (I), examples of the alkyl group represented by R include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, t-butyl, n-pentyl group, iso-pentyl group, neo-pentyl group, cyclopentyl group, 1,2-dimethylpropyl group, n-hexyl group, cyclohexyl group, 1,3-dimethylbutyl group, 1-iso-propylpropyl group, 1,2-dimethylbutyl group, n-heptyl group, 1,4-dimethylpentyl group, 2-methyl-1-iso-propylpropyl group, 1-ethyl-3-methylbutyl group, n-octyl group, 2-ethylhexyl Group, 3-methyl 1-iso-propylbutyl group, 2-methyl-1-iso-propyl group, 1-t-butyl-2-methylpropyl group, n-nonyl group, Straight chain, branched or cyclic alkyl groups having 1 to 20 carbon atoms such as 3,5,5-trimethylhexyl group;

  Examples of the aryl group of the group R include a phenyl group, a naphthyl group, a tolyl group, a furyl group, and a pyridyl group. Examples of the halogenated alkyl group include a fluorinated alkyl group, an alkyl chloride group, and an alkyl bromide group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the alkoxyalkyl group include a methoxymethyl group, a methoxyethyl group, an ethoxyethyl group, a propoxyethyl group, and a butoxyethyl group. , 3-methoxypropyl group, 3-ethoxypropyl group, methoxyethoxymethyl group, ethoxyethoxyethyl group, dimethoxymethyl group, diethoxymethyl group, dimethoxyethyl group, diethoxyethyl group and the like.

  Further, the anion of group X includes fluorine ion, chlorine ion, bromine ion, iodine ion, perchlorate ion, nitrate ion, benzenesulfonate ion, p-toluenesulfonate ion, methylsulfate ion, ethylsulfate ion, Propyl sulfate ion, tetrafluoroborate ion, tetraphenylborate ion, hexafluorophosphate ion, benzenesulfinate ion, acetate ion, trifluoroacetate ion, propionacetate ion, benzoate ion, oxalate ion, succinate ion , Malonate ion, oleate ion, stearate ion, citrate ion, pentachlorostannate ion, chlorosulfonate ion, fluorosulfonate ion, trifluoromethanesulfonate ion, hexafluoroarsenate ion, hexafluoroan Mon acid ion, molybdate ion, tungstate ion, titanate ion, zirconate ion, and among them, such as trifluoromethanesulfonic acid ion, it is preferred to use a halogen-containing anions.

  Also, there is no particular limitation as a support film, polyester-based, acrylic-based, cellulose-based, polyethylene-based, polypropylene-based, polyolefin-based, polyvinyl chloride-based, polycarbonate-based, phenol-based, urethane-based plastic film, or The thing which bonded two or more of these arbitrary things is mentioned. A polyester film having a good balance between heat resistance and flexibility is preferable, and a polyethylene terephthalate film is more preferable.

  The thickness of the binder resin for NIR film containing the NIR absorbent after coating and drying is preferably about 1 to 100 μm, particularly preferably 10 to 50 μm, in order to maintain high transparency.

  The binder resin for NIR film according to the present invention is selected by selecting a specific monomer composition, so that the adhesiveness is good even in wet heat, and peeling and foaming do not occur even though Tg is relatively low. is there.

  And since this binder resin gives good fading resistance to the dye, it is possible to prevent the fading of the dye acting as a NIR absorbent by using this, and to prevent peeling or foaming from the base material particularly during wet heat. It is possible to prepare a NIR film having no excellent adhesion.

  EXAMPLES Hereinafter, although a manufacture example and an Example are given and this invention is demonstrated in more detail, this invention is not restrict | limited at all by these.

Example 1
Preparation of binder resin In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet pipe, 17 parts by weight of lauryl methacrylate (LMA), 2 parts by weight of methacrylic acid (MAA), 61 parts by weight of methyl methacrylate (MMA) Then, 20 parts by weight of dicyclopentanyl methacrylate (DCPMA) and 60 parts by weight of toluene were charged, and the contents in the flask were heated to 79 ° C. while introducing nitrogen gas into the flask. Next, 0.6 parts by weight of a polymerization initiator dimethyl 2,2′-azobis (2-methylpropionate) was added, and the reaction was carried out for 6.5 hours while maintaining the reaction temperature at 79 to 85, resulting in a weight average molecular weight of 210,000. The polymer (binder resin) was obtained.

  2 parts by weight of diimmonium dye (CIR-1085, manufactured by Nippon Carlit Co., Ltd.) is added to 100 parts by weight of the solid content of the obtained polymer to prepare a solid content of 25%, and then dried on a 50 μm PET film. The coating was applied to a thickness of 10 μm and dried at 100 ° C. for 5 minutes to obtain an NIR absorption film.

Example 2
An NIR binder resin (hereinafter sometimes referred to as “NIR resin”) was prepared by the production method according to Example 1 and with the composition shown in Table 1 below. About each obtained resin, the NIR absorption film was produced like Example 1, and the transmittance | permeability, adhesiveness, and coating property were investigated with the following method. The results are shown in Table 2. In addition, the thing of Example 1 was also shown in the table | surface.

NIR resin composition:

Evaluation methods :
<Transmissivity>
Each resin in Table 1 was coated on a PET film (thickness 50 μm) so that the dry thickness was 10 μm, and an NIR film was prepared. First, the transmittances at 1100 nm and 430 nm of this NIR film were measured with an ultraviolet-visible spectrophotometer UVmini-1240 (Shimadzu Corporation) to obtain the initial transmittance.

  Next, each NIR film was allowed to stand at 80 ° C. × 90% RH for 300 hours, and then the transmittance at 1100 nm and 430 nm was measured again with an ultraviolet-visible spectrophotometer UV mini-1240 (Shimadzu Corporation), and wet heat It was set as the post transmittance.

<Adhesion>
The adhesion of the resin to the base film was evaluated by the base tape method. First, the resin obtained in Table 1 was applied to an equipment film (03PEEW, manufactured by Teijin Films) to a dry thickness of 25 μm, and dried at 23 ° C. for 24 hours. Next, after making a scratch of 1 mm width on the resin coating film side in a substrate pattern (100 squares), the base film side was fixed to a glass plate with a double-sided tape. Furthermore, when a commercially available tape (made by Scotch 3M) is closely attached to the coating film with a base-like scratch, and the tape is peeled off by 90 ° peeling (pulling and peeling in the direction perpendicular to the adhesive surface) The adhesion was evaluated by peeling off the coating film. The evaluation was performed in four stages of peeling of less than 0 to 15%, 15 to 35%, 35 to 65%, and 65% or more.

Result:

  The binder resin for NIR film of the present invention has good flexibility, good adhesion even in wet heat, does not peel off or foam, and also has good anti-fading properties of dyes that are NIR absorbers It is.

Therefore, the NIR film and the like prepared using the binder resin of the present invention are highly useful as films for the purpose of shielding NIR including PDP displays.

Claims (2)

Next monomer (A)-(D)
(A) Lauryl methacrylate and / or 2-ethylhexyl methacrylate 10-30% by mass
(B) Methacrylic acid 1 to 10% by mass
(C) Methyl methacrylate 50-88 mass%
(D) Cycloolefin ring-containing monomer 1 to 30% by mass
A binder resin for a near-infrared absorbing film having a Tg of 10 to 70 ° C. and a weight average molecular weight of 200,000 to 500,000, obtained by copolymerization of The monomer (D) is one or two or more kinds of monomers selected from dicyclopentanyl methacrylate, cyclohexyl methacrylate, methyl cyclohexyl methacrylate, cyclododecyl methacrylate, t-butylcyclohexyl methacrylate and isobutylcyclohexyl methacrylate. Binder resin for near infrared absorption film.