JP2008106189A - Adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive composition suitable for pressure sensitive adhesive/adhesive for functional filter with a high transparency for flat panel display (FPD), exhibiting an excellent adhesion to a plastic such as an acrylic, a polyester and a polycarbonate and exhibiting a pressure sensitive adhesive/adhesive properties to a glass substrate such as initial reworkable pressure sensitive adhesion and gradually increasing adhesion. <P>SOLUTION: The adhesive composition comprises an acrylic resin (C) with a number average molecular weight of 50,000-500,000 comprising a stem polymer of an acrylic copolymer (A) having a unit represented by general formula I, (wherein, R<SB>1</SB>is a hydrogen atom or a methyl group, m is at least two different numbers selected from 0 or integers of 1-5), and a branch polymer of an acrylic copolymer (B) having a unit represented by general formula II, (wherein the R<SB>1</SB>is a hydrogen atom or a methyl group, R<SB>2</SB>is a 1-12C alkyl group). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an adhesive composition having excellent viscosity / adhesive strength retention over time, moist heat resistance, heat resistance, and rework tackiness.

  Acrylic resins are excellent in transparency and light resistance, and demand is steadily increasing as pressure-sensitive adhesives and adhesives for flat panel displays (FPD). On the other hand, there are still many problems in terms of heat resistance, moist heat resistance, adhesive strength, and adhesive strength retention, and it is difficult to say that they have been completely solved.

  A pressure-sensitive adhesive composition, which is a material for forming a pressure-sensitive adhesive layer provided on a filter body of a plasma display panel (PDP), has been proposed (see Patent Document 1). The technique proposed in Patent Document 1 partially includes a monomer material containing 50 wt% or more of a (meth) acrylic acid alkyl ester monomer (1) having an alkyl group of C4 to 14 with respect to the total monomers. 70 weight% or more of (meth) acrylic acid alkyl ester (2) and 1 to 7 weight% of unsaturated carboxylic acid are contained as monomer units with respect to 100 weight parts of polymer / monomer mixture obtained by polymerization. It contains 0.1 to 2 parts by weight of a low molecular weight polymer having a weight average molecular weight of 2000 to 50000, and 0.1 to 1.0 part by weight of a polyfunctional (meth) acrylate having two or more (meth) acryloyl groups. is there. This is said to be excellent in reworkability (removability), wet heat storage resistance, and impact relaxation properties. As is clear from the composition, the proposed technique has a low crosslinking density and a low molecular weight, and contains a large amount of non-crosslinked polymers. In addition, since the film thickness is set to 0.5 to 2 mm, it is a so-called gel-like substance having a small strength on the base material rather than an adhesive. This has a low cohesive force of the polymer and cannot exhibit strong adhesion to the substrate. In addition, reworkability (removability) may cause cohesive failure of the polymer or stringing of the pressure-sensitive adhesive layer depending on the peeling conditions. Furthermore, it is self-evident that the durability is insufficient when continuously placed in a high temperature environment or when exposed to ultraviolet radiation harmful to the polymer.

  A method for producing a display film having electromagnetic shielding properties has been proposed (see Patent Document 2). In the technique proposed in Patent Document 2, a metal foil of a conductive material having a roughened bonding surface to an adhesive layer is bonded to a transparent plastic substrate via an adhesive layer, and the metal foil is bonded to the adhesive layer. A process of transferring the rough surface shape of the bonding surface, and a metal foil having a line width of 40 μm or less, a line interval of 200 μm or more, and a line thickness of 40 μm or less by a chemical etching process on the bonded metal foil. An adhesive having a refractive index difference of 0.14 or less between a step of forming a figure and a portion where the rough surface shape of the adhesive layer including the geometric figure formed by removing the metal foil is transferred. The manufacturing method of the film for displays which has electromagnetic wave shielding property and transparency characterized by including the process to coat | cover.

  As shown in Patent Document 2, in the electromagnetic wave shielding film using a conductive mesh such as a copper mesh, not only the electromagnetic wave shielding property but also the transparency (visible light transmittance) of the sheet is an extremely important property. is there. Commercially available conductive mesh has the latest research results in line width (around 10 μm), line spacing (around 250 microns), and line thickness (around 25 μm) to ensure higher aperture ratio and higher visibility. Has been. These improvement studies are to improve the clarity and visibility of images, and all are to increase the transparency of the electromagnetic shielding film and to reduce the haze. For this purpose, if described based on the technique proposed in Patent Document 2, light scattering and refraction on the roughened adhesive surface located on the transparent plastic is eliminated, and this The adhesive that covers the rough surface profile does not trace, and the adhesive penetrates completely into the small vessel made of conductive material (for example, copper) It is a very important requirement that no gaps or bubbles remain.

  When light is refracted and scattered on the adhesive surface (interface), the amount of transmitted light is reduced, which causes haze deterioration. That is, the transparency and sharpness of the film are impaired. In order to improve this, the proposal of Patent Document 2 defines the refractive index of the adhesive to be overcoated.

  When the adhesive that overcoats the rough surface profile traces, light scattering occurs on the surface of the adhesive to be overcoated, the amount of transmitted light is reduced, and the visible light transmittance and haze of the film are deteriorated. In the proposal of Patent Document 2, the adhesive to be overcoated is a solvent-diluted adhesive having no characteristics, and the rough surface profile cannot be repaired and a smooth surface cannot be formed.

  If gaps or bubbles remain in the vessel, light is refracted and scattered in the voids and bubble-containing portions, and the transparency of the film is greatly impaired. It is no longer suitable for display. In the proposal of Patent Document 2, the adhesive to be overcoated is a solvent-diluted adhesive having no characteristics, and the adhesive penetrates to the inside of the mesh as shown as “the process of coating with an adhesive”. Absent.

  In the technique proposed in Patent Document 2, it is considered that a small difference in refractive index is important, and the correspondence is limited only to eliminating refraction. Regarding the adhesive that covers the rough surface profile not to trace the rough surface profile, the adhesive is used diluted with an organic solvent, so it is inevitable to trace the unevenness of the substrate as the volume shrinks during drying. No measures have been taken. The fact that the adhesive completely penetrates into a minute container made of a conductive material (for example, copper) and no gaps or bubbles remain in the container is disclosed in claim 1 of Patent Document 2. As mentioned above, the technique of Patent Document 2 is “including a process of coating with an adhesive”, and the adhesive penetrates into a small vessel made of a conductive material (for example, copper). Absent. Moreover, the adhesive agent which patent document 2 discloses does not have the capability to osmose | permeate in the container on the recessed part which an electroconductive substance forms.

  In Patent Document 2, the results of applying this technology to a practical copper mesh (line width (around 10 μm), line interval (around 250 μm), line thickness (around 25 μm)) are shown in the examples. Visible light transmittance is only 70% at most, and haze, which is an important requirement, has not been evaluated at all. When the visible light transmittance is about 70%, the haze is at least 10 or more, and it is estimated that this is a technique lacking practicality in combination with the visible light transmittance.

  This means that the adhesive covering the rough surface profile does not trace, the adhesive penetrates completely into a small vessel made of conductive material (eg copper), and no gaps or bubbles remain in the vessel. This is because no countermeasures are taken against it, there is no refraction, the adhesive that covers the rough surface profile does not trace the rough surface profile, and it adheres even in a small vessel made of conductive material (eg copper) It was strongly desired that the agent penetrated perfectly and no gaps or bubbles remained in the vessel.

  Non-Patent Document 1 discloses a technique for manufacturing an electromagnetic wave shielding film by directly applying and curing a transparent resin solution on a conductive mesh as an improved technique of the adhesive layer pressure bonding method described above. It can be seen that various improvements have been made and implemented in the coating technique. Measures to ensure that the adhesive covering the rough surface profile does not trace, and that the adhesive penetrates completely into a small vessel made of conductive material (eg copper), leaving no gaps or bubbles in the vessel. Part of the technology is also included.

The transparent resin to be applied is not preferred because it is diluted with a solvent because the underlying lattice pattern is raised and the flatness cannot be secured as the film thickness decreases due to shrinkage of the volume during drying (originally deposited). It has been shown that it must be a solvent resin. Solvent-free, fluid, and acrylic UV curable resins that can be applied to substrates with comparatively simple viscosity control, such as glue, penetrability, and leveling adhesives. The rheological aptitude for the coating workability was poor, and although it was improved as compared with the above-mentioned pressure bonding method, it was still insufficient. For example, the adhesion of bubbles to the mesh corner and the distortion of transparency due to residual distortion at the time of curing were not satisfactory.
JP-A-2005-23133 Japanese Patent Laid-Open No. 10-41682 Nomura, Imaizumi, Takahashi, Hayashi, Hitachi Chemical Technical Report No. 42 “Electromagnetic wave shielding film for PDP”, [online], January 2004, Hitachi Chemical Co., Ltd. [searched on May 30, 2006], Internet <URL: http://www.hitachi-chem.co .jp / japanese / report / index.html>

  Suitable for adhesives and adhesives for functional filters with high transparency for flat panel displays (FPD). Excellent adhesion to plastics such as acrylic, polyester, polycarbonate, and initial bonding to substrate glass The adhesive composition has a rework tackiness and a viscosity / adhesiveness that gradually increases with time.

  The present invention uses an acrylic copolymer (A) having a unit represented by the following general formula in a molecular chain as a backbone polymer,

(Here, R1 is a hydrogen atom or a methyl group, and m is two or more different values selected from 0 or an integer of 1 to 5.)
An acrylic copolymer (B) having a unit represented by the following general formula in the molecular chain is used as a branch polymer.

(Here, R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 1 to 12 carbon atoms.)
An adhesive composition comprising an acrylic resin (C) having a number average molecular weight of 5 to 500,000 is provided.

  The adhesive composition of the present invention is used as a pressure-sensitive adhesive having excellent adhesion to a substrate film and good rework adhesion to a substrate glass for a functional filter used in a flat panel display (FPD). Can do.

  The adhesive composition of the present invention is not only excellent in viscosity and adhesiveness, but also exhibits the appearance of the adhesive, the appearance change and deterioration of the adherend even when placed in a harsh environment such as high temperature and high humidity. Good viscosity and adhesiveness are maintained and exhibited without any change and the same as in the initial stage.

  The present invention uses an acrylic copolymer (A) having a unit represented by the following general formula in a molecular chain as a backbone polymer,

(Here, R1 is a hydrogen atom or a methyl group, and m is two or more different values selected from 0 or an integer of 1 to 5.)
An acrylic copolymer (B) having a unit represented by the following general formula in the molecular chain is used as a branch polymer.

(Here, R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 1 to 12 carbon atoms.)
It is an adhesive composition containing an acrylic resin (C) having a number average molecular weight of 5 to 500,000.

  In the adhesive composition of the present invention, the acrylic resin (C) includes the acrylic copolymer (A) as a trunk polymer (hereinafter also referred to as a matrix) and the acrylic copolymer (B) as a branched polymer (hereinafter also referred to as a branch). ) And a graft copolymer.

  The acrylic resin (C) (graft copolymer) of the present invention comprises an acidic functional group-containing monomer mixture represented by the following structural formula, an acrylic monomer copolymerizable therewith, and a (meth) acrylic acid ester It can be produced by copolymerization with a macromonomer (hereinafter also referred to as MM). (Reference for production method of graft copolymer by macromonomer method; “Radical Polymerization Handbook” Mikiharu Tsujiike, supervised by Tsuyoshi Endo, published by NTS (1999), p156-p158, p191-p194)

(Here, R1 is a hydrogen atom or a methyl group, and m is two or more different values selected from 0 or an integer of 1 to 5.)
The acidic functional group-containing monomer mixture represented by the above structural formula is a mixture of two or more monomers in which m is arbitrarily selected from 0 or an integer of 1 to 5. As the acidic functional group-containing monomer mixture, two or more monomers arbitrarily selected from acrylic acid, β-carboxyethyl acrylate, acrylic acid trimer, methacrylic acid, β-carboxyethyl methacrylate, methacrylic acid trimer, and the like Mixtures are exemplified.

  An acidic functional group-containing monomer mixture is, for example, copolymerized by mixing 20% of m = 0 monomer, 40% of m = 1 monomer, and 40% of m = 2-5 monomer. When this is done, there is a strong tendency to exhibit superior functions as compared to, for example, a case where a monomer of m = 0 (for example, acrylic acid) is used alone. When the acidic functional group-containing monomer mixture is copolymerized, there is a tendency that the tackiness and adhesiveness of the acrylic resin to the adherend are dramatically improved. Most importantly, for example, when a monomer of m = 0 (for example, acrylic acid) is used alone, the water resistance and heat-and-moisture resistance of the adhesive tend to be extremely poor. For example, in the case of copolymerization as a mixture as described above (m = 0 20%, m = 1 40%, m = 2 to 540%) (acidic functional group-containing monomer mixture), to the adherend Adhesive and tackiness of the adhesive are not only very good, but the transparency, adhesion and tackiness of the adhesive are the same as before the test without any change in the long-term water resistance test and moist heat resistance test. Maintained and demonstrated above.

  The acidic functional group-containing monomer mixture is copolymerized so that the acid value of the acrylic resin (C) is preferably 1 to 50 mgKOH, more preferably 1.2 to 35 mgKOH, and even more preferably 1.5 to 20 mgKOH. Is desirable. When the acid value is less than 1 mg KOH, the adhesion and tackiness to the adherend may be deteriorated, and the water resistance and moist heat resistance tend to be deteriorated. When the acid value exceeds 50 mgKOH, the heat and moisture resistance and water resistance deteriorate, and the adhesive layer tends to swell, whiten and peel easily.

  Examples of acrylic monomers that can be copolymerized with the acidic functional group-containing monomer mixture include methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, and acrylic. Lauryl acid, stearyl acrylate, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, p-hydroxymethylcyclohexylmethyl acrylate, 2,2,2-trifluoroethyl acrylate, methyl methacrylate, ethyl methacrylate, methacryl N-butyl acid, t-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, p Hydroxymethyl cyclohexyl methacrylate, 2,2,2-trifluoroethyl methacrylate, .gamma. acryloxypropyltrimethoxysilane, .gamma.-methacryloxypropyl trimethoxysilane, etc. .gamma.-methacryloxypropyl triethoxysilane, and the like. These acrylic monomers may be used alone or as a mixture of two or more. Among these acrylic monomers, those having 4 to 12 carbon atoms in the ester group tend to be desirable, and adhesiveness, tackiness, and water resistance may be improved.

  In the adhesive composition of the present invention, the acrylic resin (C) comprises an acidic functional group-containing monomer mixture and an acrylic monomer copolymerizable therewith, and preferably a (meth) acrylic acid ester macromonomer (hereinafter referred to as “a”). , Also referred to as MM).

  As the (meth) acrylate macromonomer (MM), polymethyl methacrylate macromonomer (for example, Aron Macromer AA-6 manufactured by Toagosei Co., Ltd.), polybutyl acrylate macromonomer (for example, Toagosei Co., Ltd.) Aron Macromer AB-6), polyethyl 2-ethylhexyl acrylate macromonomer (for example, Aron Macromer AJ-7 manufactured by Toagosei Co., Ltd.), polymethyl methacrylate / 2-hydroxyethyl methacrylate) macromonomer (for example, Toago) Aron Macromer AA-714 manufactured by Synthetic Corporation is exemplified. These (meth) acrylic acid ester macromonomers (MM) may be used alone or as a mixture of two or more.

The macromonomer used in radical polymerization refers to a radical polymerizable oligomer or polymer having a (meth) acryloyl group at one end of a molecular chain. In general, the number average molecular weight is about several thousand to several tens of thousands. (References; (1) "Radical Polymerization Handbook", supervised by Mikiharu Tsunoike, Takeshi Endo, published by NTS (1999), p189-p194, (2) "Reactive Polymers and Their Applications", Inc. Published by Toray Research Center (1998), p48-p56, p231-232)
In the present invention, the (meth) acrylic acid ester macromonomer refers to a polymer or oligomer having a radical polymerizable (meth) acryloyl group at one end of the molecular chain, and the molecular chain (oligomer or polymer) is
(1) an oligomer obtained by copolymerizing a poly (meth) acrylic acid ester, and (2) a radical polymerizable monomer copolymerizable with (meth) acrylic acid ester, such as styrene or acrylonitrile, Refers to a copolymer.

  The adhesive composition containing the acrylic resin (C) of the present invention has a controlled polymer viscosity (rheology) and, in combination with the self-structuring function inherent to the graft copolymer, is compatible with the adherend, wettability, and permeability. There is a strong tendency to improve and improve. Further, preferably, the mechanical properties inherent in the (meth) acrylic acid ester macromonomer (MM) are reflected, and the toughness of the adhesive tends to be improved. Furthermore, good conformability, wettability, and permeability tend to eliminate an air layer at the interface between the adhesive and the adherend and give an adhesive article having good transparency and low haze.

  Further surprisingly, preferably, the acrylic resin (C) is graft-copolymerized by copolymerization of a (meth) acrylic ester macromonomer (MM), so that a polyisocyanate compound further blended in a normal state. Inadvertent reactivity between the epoxy resin and the acidic functional group-containing monomer mixture and the hydroxyl group-containing compound is controlled, and an adhesive having excellent storage stability is produced. Furthermore, under appropriate curing reaction conditions, the reactivity of the polyisocyanate compound, epoxy resin, and the like with the acidic functional group-containing monomer mixture and the hydroxyl group-containing compound is remarkably accelerated, and it is tough, heat resistant, and moisture resistant. There is a tendency to obtain adhesive products with excellent heat resistance and impact resistance.

  The (meth) acrylic acid ester macromonomer (MM) is preferably 0.2 to 20% by weight, more preferably based on 100 parts by weight of the acrylic resin matrix having a chain derived from the acidic functional group-containing monomer mixture. It is desirable to introduce 0.5 to 12% by weight, more preferably 0.5 to 8% by weight. When the amount of (meth) acrylic acid ester macromonomer (MM) introduced is less than 0.2% by weight, the polymer viscosity tends to be insufficiently controlled. The adhesiveness may decrease and the adhesive strength may decrease slightly. When the amount of (meth) acrylic acid ester macromonomer (MM) introduced exceeds 20% by weight, the adhesive force tends to decrease, and the tendency to easily peel off is observed.

  In the present invention, an acrylic copolymer (A) having a unit represented by the following general formula in the molecular chain:

(Here, R1 is a hydrogen atom or a methyl group, and m is two or more different values selected from 0 or an integer of 1 to 5.)
The glass transition temperature (hereinafter also referred to as Tg) is preferably −80 to 30 ° C., more preferably −55 to 10 ° C., and still more preferably −55 to 0 ° C. When the Tg of the acrylic copolymer (A) is less than −80 ° C., the polymer cohesive force tends to be too small, and the adhesive tends to easily cause cohesive failure, leading to a decrease in adhesive strength. When the Tg of the acrylic copolymer (A) exceeds 30 ° C., the toughness of the adhesive is impaired and the impact resistance tends to deteriorate.

Here, in the present invention, the glass transition temperature (Tg) is determined by the method described in “Mechanical properties of polymer” (translated by JENielsen, translated by Shigeharu Onoki) (published by Kagaku Dojin, 1975) (p15-p27). It calculated according to. That is,
1 / Tg = Σ (wi / Tgi)
(Here, Tg represents the Tg of the acrylic resin (absolute temperature K), Wi represents the copolymerization amount (weight fraction) of the i monomer, and Tgi represents the glass transition temperature of the homopolymer prepared from the i monomer. .)
Calculated by Further, the Tg of the homopolymer prepared from the monomer to be copolymerized is the value described in the above-mentioned document “Mechanical properties of polymer”, and acrylic monomer sales companies (for example, Mitsubishi Rayon, Toagosei, (Nippon Catalyst Industries, Nippon Oil & Fat etc.) The values listed in the catalog were adopted and used.

  The number average molecular weight (hereinafter also referred to as Mn) of the acrylic resin (C) is 5 to 500,000. The number average molecular weight of the acrylic resin (C) is preferably 80 to 350,000, and more preferably 100 to 300,000. When the Mn of the acrylic resin (C) is less than 50,000, the polymer cohesive force is weak, resulting in a decrease in adhesive force and deterioration in impact resistance. When the Mn of the acrylic resin (C) exceeds 500,000, the viscosity of the adhesive becomes too strong, the wettability to the adherend and the familiarity are deteriorated, and the adhesive force is reduced.

  Here, in the present invention, the number average molecular weight of the acrylic resin is a polystyrene standard whose molecular weight is determined using gel permeation chromatography (GPC) (for example, “HLC-8220 GPC” system manufactured by Tosoh Corporation). (For example, standard POLYSTYRENE manufactured by GL Sciences Inc.) was measured as a molecular weight standard.

  The acrylic resin (C) of the present invention is preferably produced by radical copolymerization, and can be used for any polymerization method such as bulk polymerization, suspension polymerization, dispersion polymerization, precipitation polymerization, solution polymerization, and emulsion polymerization. Can be achieved.

  In consideration of the post-process using the produced polymer, it is desirable to carry out in a solvent-free or non-aqueous solvent system such as bulk polymerization, dispersion polymerization, precipitation polymerization, and solution polymerization.

  The production of the acrylic resin (C) is preferably carried out in a polymerization system substituted with an inert gas such as nitrogen gas, argon gas or helium gas. At this time, the oxygen concentration of the polymerization system is preferably 5 vol% or less, more preferably 2 vol% or less, and still more preferably 0.5 vol% or less. When the oxygen concentration in the polymerization system exceeds 5 vol%, the radical polymerization reaction is influenced by the oxygen in the system and may not proceed sufficiently. That is, the polymerization rate is remarkably slow, and a large amount of low-polymerization polymer may be generated due to telomerization by oxygen, which tends to cause coloration of the adhesive and a decrease in water resistance.

  The acrylic resin (C) is produced preferably at a polymerization temperature of 50 to 150 ° C, more preferably 60 to 140 ° C. When the polymerization temperature is less than 50 ° C., the polymerization rate is difficult to increase, and the production may take a very long time. A further concern is that the heat resistance of the produced polymer may be degraded. When the polymerization is carried out at a temperature exceeding 150 ° C., the stability of the polymer terminal radical tends to be lowered, and it may be difficult to produce a polymer having a desired molecular weight and molecular weight distribution.

  Examples of the organic solvent that can be used as a solvent in the solution polymerization include toluene, xylene, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, amyl acetate, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n- Butyl alcohol, t-butyl alcohol, cyclohexanone, cyclohexane, hexane, heptane, methylcyclohexane, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, Examples include tripropylene glycol and 1,4-butanediol. These organic solvents may be used alone or as a mixture of two or more.

  Among these solvents, chain transfer such as ethyl acetate and n-propyl acetate is necessary in order to prevent coloration of the polymer and deterioration of heat resistance, and when solvent removal is required when producing an adhesive. Small constants are recommended.

  In the present invention, the acrylic resin (C) preferably contains an acrylic monomer containing an acidic functional group-containing monomer mixture in the presence of a hindered amine compound and an organic peroxide, and a (meth) acrylic acid ester macromonomer (MM It is recommended to be produced by radical copolymerization. More preferably, in the presence of a reaction product of a hindered amine compound and an organic peroxide, an acrylic monomer containing an acidic functional group-containing monomer mixture and a (meth) acrylic ester macromonomer (MM) are radicalized. It is desirable to produce by copolymerization.

  The radical copolymerization reaction proceeds by a living radical polymerization mechanism, and despite the copolymerization of (meth) acrylate macromonomer (MM), the molecular weight distribution is narrow and a high molecular weight acrylic resin (C) can be produced. When the acrylic resin (C) produced by this production method is used, the rheology control of the adhesive is easy and optimized, and not only the coating workability is improved, but also the wettability and permeability to the adherend. There is a strong tendency to improve the toughness, mechanical strength, heat resistance, and adhesive strength of the adhesive.

  Examples of hindered amine compounds include 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, and bis (1,2,2,6). , 6-pentamethyl-4-piperidyl) sebacate, 3-dodecyl-1- (2,2,6,6-tetramethyl-4-piperidinyl) pyrrolidine-2,5-dione, N-methyl-3-dodecyl-1 -(2,2,6,6-tetramethyl-4-piperidinyl) pyrrolidine-2,5-dione, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, N-methyl-4-benzoyloxy Examples include -2,2,6,6-tetramethylpiperidine. The hindered amine compound may be used alone or as a mixture of two or more.

  Examples of organic peroxides include benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxybenzoate, cumene hydroperoxide, t-butyl hydroperoxide, and dicumyl peroxide. Is done. The organic peroxide may be used alone or as a mixture of two or more.

The hindered amine compound and the organic peroxide are preferably 1 × 10 ⁻⁴ mol to 2.5 mol, more preferably 5 × 10 ⁻⁴ mol to 2.0 mol per mol of the hindered amine compound. Used in mole ratios.

When the amount of the organic peroxide used is less than 1 × 10 ⁻⁴ mol relative to 1 mol of the hindered amine compound, the polymerization rate is hardly increased, the polymerization efficiency tends to be poor, and only a small molecular weight tends to be produced. is there.

  When the amount of the organic peroxide used exceeds 2.5 moles with respect to 1 mole of the hindered amine compound, the living property of the polymerization is lost, and a low molecular weight polymer tends to be produced in a large proportion. There is a tendency that the molecular weight distribution of the acrylic resin (C) is widened.

  The hindered amine compound is preferably 0.002 to 20.0 based on 100 parts by weight of the total amount of the acrylic monomer containing the acidic functional group-containing monomer mixture and the (meth) acrylic ester macromonomer (MM). It is desirable to use by weight%, more preferably 0.005 to 15.0% by weight, and still more preferably 0.02 to 12.0% by weight.

  The amount of the hindered amine compound used is less than 0.002% by weight based on 100 parts by weight of the total amount of the acrylic monomer containing the acidic functional group-containing monomer mixture and the (meth) acrylate macromonomer (MM). In this case, it is difficult to increase the polymerization rate, and it takes a long time for the polymerization and the utility is apt to be lost.

  The amount of the hindered amine compound used is 20.0% by weight based on 100 parts by weight of the total amount of the acrylic monomer containing the acidic functional group-containing monomer mixture and the (meth) acrylate macromonomer (MM). If it is used in excess, coloring may be seen in the polymer, which may cause a problem in practice.

  A reaction product of a hindered amine compound and an organic peroxide can be produced, for example, by simply mixing the hindered amine compound and the organic peroxide in a container substituted with an inert gas such as nitrogen gas or helium gas. it can.

  Below, an example of the preferable aspect of acrylic resin (C) manufacture is shown. Of course, the present invention is not limited to this.

  A polymerization solvent (for example, a mixed solvent of ethyl acetate / n-propyl acetate (80/20 weight ratio)) is charged into a flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device. Nitrogen gas is introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask is measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it is confirmed that the oxygen concentration is less than 0.5 vol%.

  While continuing the bubbling of nitrogen gas, a predetermined amount of a hindered amine compound such as 4-benzoyloxy-2,2,6,6-tetramethylpiperidine is charged into a flask and dissolved uniformly. If dissolution is possible, an organic peroxide such as benzoyl peroxide is charged in an equimolar amount with the hindered amine compound and stirring is continued. The temperature rise is started, the temperature is raised to 80 ° C. in 30 minutes, and the temperature is kept at 80 ° C. below.

  Monomer, for example, 2-ethylhexyl methacrylate / n-butyl acrylate / acid-containing monomer mixture (for example, m = 0 20%, m = 1 40%, m = 2 and 3 40% in the following structural formula) A mixture of)

(Here, R1 is a hydrogen atom or a methyl group, and m is two or more different values selected from 0 or an integer of 1 to 5.)
A mixed monomer of “Aron Macromer AA-6” (methyl methacrylate macromonomer manufactured by Toagosei Co., Ltd.) (= 5/91/1/3; weight ratio) was dropped into the flask in 2 hours and immediately after the completion of dropping. Sampling is performed, and the molecular weight and the polymerization rate are measured. When the polymerization rate reaches 100%, the polymerization is terminated and cooling is started.

  The acrylic resin (C) can be manufactured by the above.

  The adhesive of the present invention can be used alone with the acrylic resin (C), or can be used by blending a curing agent or the like with the acrylic resin (C).

In other words,
(1) After the acrylic resin (C) is directly applied to one of the adherends, the organic solvent is removed by drying at a temperature of about room temperature to 150 ° C. The other adherend is pressure-bonded to this by hot pressing or the like, and if necessary, heated at 50 to 150 ° C. to produce an adhesive article.

  (2) To the acrylic resin (C), for example, a radical polymerizable diluent such as 2-ethylhexyl acrylate and epoxy diacrylate oligomer, and a crosslinking agent are added and mixed uniformly. Further, as a polymerization initiator, for example, a redox initiator such as cumene hydroperoxide or cobalt octylate is added to produce a radical curable adhesive. If a photopolymerization initiator such as Michler's ketone is added instead of the redox initiator, a photocurable adhesive can be produced.

  (3) A two-component curable adhesive is produced by adding a curing catalyst such as 3-aminopropyltrimethoxysilane and bisphenol A type epoxy resin and a curing agent to the acrylic resin (C).

  In addition to the acrylic resin (C), the adhesive composition of the present invention includes talc, bentonite, montmorillonite, calcium carbonate, zinc oxide, quartzite powder, glass powder, mica, potassium titanate whisker, glass wool, carbon fiber, etc. Reinforcing and filling fillers, silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and 3,4-epoxycyclohexylpropyltriethoxysilane can be blended. .

  The adhesive composition of the present invention can be applied to an adherend, and another adherend is pressure-bonded or bonded in a sheet form, and preferably subjected to heat treatment to obtain an adhesive article. . In addition, the adhesive is applied on a peelable protective film, heated at an appropriate temperature, preferably 60 to 120 ° C. for an appropriate time, preferably 30 seconds to 10 minutes, and after passing through the B stage, Can be heat-cured and then bonded to the adherend.

  The adhesive composition of the present invention preferably comprises a hydroxyl group-containing acrylic monomer and an acidic functional group-containing monomer mixture so that the acrylic resin (C) has a hydroxyl value of 10 to 60 mgKOH and an acid value of 1 to 50 mgKOH. It can superpose | polymerize and can mix | blend a polyisocyanate compound as a hardening | curing agent, and can be used as an adhesive agent for FPD function filters.

  The functional filter to which the adhesive composition of the present invention is applied is more preferably a plasma display panel (PDP) functional filter (front filter) such as an antireflection film, a color tone adjustment film, a neon light cut film, or a near infrared cut film. And more preferably an electromagnetic wave shielding sheet (hereinafter also referred to as EMI sheet) for a plasma display panel (PDP).

  Examples of the hydroxyl group-containing acrylic monomer contained in the adhesive composition of the present invention include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, p-hydroxymethylcyclohexyl acrylate, and methacrylic acid. Examples include acrylic monomers having a hydroxyl group in the molecule, such as 2-hydroxyethyl, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate. These hydroxyl group-containing acrylic monomers may be used alone or as a mixture of two or more.

  The hydroxyl group-containing acrylic monomer is desirably copolymerized so that the hydroxyl value of the acrylic resin (C) is preferably 10 to 60 mgKOH, more preferably 12 to 55 mgKOH, and still more preferably 12 to 35 mgKOH. When the hydroxyl value of the acrylic resin (C) is less than 10 mgKOH, the degree of crosslinking is insufficient, the water resistance and the heat-and-moisture resistance are deteriorated, and the haze tends to gradually deteriorate with time. When the hydroxyl value of the acrylic resin exceeds 60 mgKOH, the degree of cross-linking becomes too high, and the impact resistance of the adhesive surface may deteriorate. Moreover, when bridge | crosslinking with polyisocyanate, the case where the adhesiveness to a base film is impaired is seen.

Here, in the present invention, the hydroxyl value of the acrylic resin (C) is based on the molecular weight (M) and copolymerization amount (Y%) of the copolymerized hydroxyl-containing acrylic monomer.
Hydroxyl value of acrylic resin (mgKOH) = Y / M × 561
Calculated by

  Examples of the polyisocyanate compound contained in the adhesive composition of the present invention include compounds having two or more isocyanate groups (—NCO) in the molecule such as tolylene diisocyanate, metaxylene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. Illustrated. These polyisocyanate compounds may be used alone or as a mixture of two or more.

  In the polyisocyanate compound, the number of moles of NCO in the polyisocyanate is preferably 0.6 to 2.0, more preferably 0.75 to 1.6, relative to the number of moles of hydroxyl group in the acrylic resin (C). More preferably, it is blended so as to be 0.8 to 1.2. (Hereinafter, the ratio of the number of moles of NCO used in the polyisocyanate to the number of moles of hydroxyl group in the acrylic resin (C) is hereinafter also referred to as the NCO index). When the NCO index is less than 0.6, a large amount of unreacted hydroxyl groups in the acrylic resin are likely to remain, and there is a tendency that the water resistance and moist heat resistance deteriorate. Moreover, since the crosslinking density is lowered, the toughness of the adhesive / adhesive tends to be slightly lowered. When the NCO index exceeds 2.0, the sticky / adhesive tends to foam by reacting with moisture, and the sticky / adhesive surface may become brittle. Moreover, the crosslinking density becomes too high, and the tendency for adhesiveness and adhesive force to fall is seen.

  The adhesive of the present invention preferably further contains a tackifier. A tackifier is a compound that raises the glass transition temperature of a binder having a low glass transition temperature to the room temperature region to improve and improve the tackiness and adhesiveness.

  Examples of the tackifier include petroleum resin, rosin, terpene resin, and terpene phenol resin. These tackifiers may be used alone or as a mixture of two or more.

  The tackifier is preferably blended in an amount of 5 to 40 phr, more preferably 8 to 30 phr, and still more preferably 10 to 25 phr with respect to the acrylic resin.

  When the amount of tackifier based on the acrylic resin is less than 5 phr, the expected tackiness and adhesiveness may not be obtained. When the amount of the tackifier with respect to the acrylic resin exceeds 40 phr, the weather resistance is deteriorated and a yellowing tendency is observed with time, so that it may be slightly inappropriate for FPD use.

  In the present invention, it is recommended to blend a terpene phenol resin as a tackifier. When the terpene phenol resin is blended, there is a tendency that the adhesiveness and adhesion to the substrate glass can be arbitrarily controlled.

  Examples of the terpene phenol resin include “YS Polystar T-145”, “YS Polystar T-130”, and “YS Polystar T-115” (the product of Yashara Chemical Co., Ltd.). These terpene phenol resins may be used alone or as a mixture of two or more.

  The adhesive composition of the present invention contains a graft copolymer (acrylic resin (C)). It has excellent wettability and conformability to the adherend, and in particular has good adhesion and reworkability to glass substrates used in flat panel displays (FPD). The adhesive composition of the present invention is also excellent in transparency. Therefore, the adhesive composition of the present invention is preferably recommended for bonding a front functional filter of a flat panel display (FPD). Furthermore, it should be noted that the adhesive has a self-structuring phenomenon inherent to the graft copolymer, and the adhesive has the property of penetrating and penetrating fine irregularities. Therefore, the above-described typical electromagnetic wave shielding sheet (practical copper mesh (line width (about 10 μm), line interval (about 250 μm), line thickness (about 25 μm)) penetrates without any obstacles, The uneven surface of the base material is also smoothly repaired, and a transparent electromagnetic wave shielding sheet having a high total light transmittance of 80% or more and a low haze can be provided.

  In addition, the chain represented by the following structural formula is

(Here, R1 is a hydrogen atom or a methyl group, and m is two or more different values selected from 0 or an integer of 1 to 5.)
It is a carboxylic acid unit having a characteristic structure of having COOH at a distance from the main chain, and there is a strong tendency to dramatically improve and improve the adhesion and adhesion to the adherend. In particular, the adherend is remarkable in the case of optical glass frequently used for functional filters, and has rework adhesiveness, while exerting strong adhesiveness from the initial stage of bonding, and the adhesiveness is further improved over time. There is a tendency to become stronger. This property is exhibited without change even when the bonding member is exposed to a high temperature of, for example, 80 ° C. or higher, or when exposed to a high temperature and high humidity of 60 ° C. and 90% RH. The

  At the same time, the appropriate hydroxyl value and the urethane bond formed by reacting with polyisocyanate improves adhesion and adhesion to polyester film (hereinafter also referred to as PET), which is often used as a base film, and is transparent. Improvement, haze reduction, and impact resistance improvement are observed.

  Furthermore, the chain represented by the following structural formula in acrylic resin

(Here, R1 is a hydrogen atom or a methyl group, and m is two or more different values selected from 0 or an integer of 1 to 5.)
(Exhibits strong adhesion to glass substrates), urethane bond formed by reaction with polyisocyanate (strong adhesion to PET), graft copolymer (adhesive) with (meth) acrylate macromonomer on the branch The toughness of the agent, familiarity with the adherend, improvement of the wetting property, the development of entropy elasticity) are mutually emphasized, and the impact resistance of the glass substrate to which the functional filter is bonded is also greatly improved. The tendency to do is seen. As a result, the impact resistance of the glass substrate is improved, the functional filter can be directly attached to the glass substrate, the sharpness of the image is improved, and a high-quality image without image distortion or distortion is possible. The tendency to do is seen.

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

  In the examples and comparative examples, the composition ratio represents a weight ratio unless otherwise specified.

  (1) The number average molecular weight of the acrylic resin is determined by using gel permeation chromatography (GPC) (for example, “HLC-8220 GPC” system manufactured by Tosoh Corporation), and a polystyrene standard (for example, GL) having a defined molecular weight. Science standard POLYSTYRENE) was measured as a molecular weight standard.

  (2) The heating residue was measured according to JIS K 5400-1997.

[Evaluation method as an adhesive for FPD functional filters]
(3) Light transmittance and haze were measured in accordance with JIS K 7136 (2000) using “NDH 2000” (Nippon Denshoku Industries Turbidimeter).

  (4) Adhesion was measured using a tensilon at a test temperature of 23 ° C. in accordance with JIS Z 0237 (2000).

(5) In the heat and humidity resistance test of the adhesive, the test piece was allowed to stand in an atmosphere of 60 ° C. and 90% RH for 1000 hours, and then the tackiness, light transmittance, and haze were measured.
[Rheology evaluation method for adhesives and adhesives (evaluation of thixotropic properties)]
(6) The rheology of the adhesive was measured at 25 ° C. using a “VAR Visco Analyzer” manufactured by Jusco International. The measurement conditions are as follows.

[Rheology measurement conditions]
Manual measurement once, measurement interval 2.000E4 + 0 s
Shear rate table Shear rate 1.000E + 0 − 1.000E + 3 1 / s
Delay time 1.015E + 0-1.6000E + 1 s
Integration time 1.030E + 0 − 3.100E + 1 s
Thixotropic properties were determined when the viscosity decreased with increasing shear rate.

[Production example of acrylic resin]
[Manufacture of acrylic resin (1)]
400 g of ethyl acetate / n-propyl acetate (= 50/50) was charged as a polymerization solvent into a 1-liter four-necked flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  While the bubbling of nitrogen gas was continued, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine was charged to the flask in an amount of 0.4% by weight of the mixed monomer, and dissolved uniformly. If dissolution is possible, benzoyl peroxide is charged in an equimolar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and the temperature rise is started. The temperature was raised to 80 ° C. in 30 minutes, and then the temperature was maintained at 80 ° C.

  2-ethylhexyl methacrylate / n-butyl acrylate / acidic functional group-containing monomer mixture (in the following structural formula, R1 = H, m = 0 (20%), m = 1 (40%), m = 2 ( 20%), m = 3 (20%) monomer mixture)

/ The mixed monomer of “Aron Macromer AA-6” (polymethyl methacrylate macromonomer of Toagosei Co., Ltd.) (= 5/91/1/3) (Tg excluding “Aron Macromer AA-6” is −48 400 g) was dropped into the flask in 2 hours. After completion of the dropping, polymerization was performed for 4 hours, and then cooled to room temperature to produce an acrylic resin (1). The acrylic resin (1) has a polymer composed of 2-ethylhexyl methacrylate / n-butyl acrylate / acid functional group-containing monomer mixture (the above structural formula) as a backbone polymer, and a polymer portion of “Aron Macromer AA-6” ( It is a graft copolymer using polymethyl methacrylate) as a branch polymer.

  FIG. 1 shows the polymerization behavior of the acrylic resin (1).

  It can be seen that the acrylic resin (1) is produced by living radical polymerization. The acrylic resin (1) had a heating residue of 50.2%, an acid value of 3.7 mgKOH, and a number average molecular weight of 150,000.

[Manufacture of acrylic resin (2)]
400 g of ethyl acetate / n-propyl acetate (= 50/50) was charged as a polymerization solvent into a 1-liter four-necked flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  While the bubbling of nitrogen gas was continued, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine was charged to the flask in an amount of 0.4% by weight of the mixed monomer, and dissolved uniformly. If dissolution is possible, benzoyl peroxide is charged in an equimolar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and the temperature rise is started. The temperature was raised to 80 ° C. in 30 minutes, and then the temperature was maintained at 80 ° C.

  2-ethylhexyl methacrylate / n-butyl acrylate / “β-CEA” (acidic functional group-containing monomer mixture, monomer from Rhône-Poulenc) (in the following structural formula, R1 = H, m = 0 ( 20%), m = 1 (40%), m = 2 and m = 3 (40%) monomer mixture)

/ 400 g of “Aron Macromer AA-6” (= 5/91/1/3) mixed monomer (Tg excluding “Aron Macromer AA-6” was −48 ° C.) was dropped into the flask in 2 hours. Then, after completion of the dropwise addition, polymerization was performed for 4 hours, and then cooled to room temperature to produce an acrylic resin (2).

  The acrylic resin (2) has a polymer composed of 2-ethylhexyl methacrylate / n-butyl acrylate / “β-CEA” as a backbone polymer, and a polymer part (polymethyl methacrylate) of “Aron Macromer AA-6” as a branched polymer. And a graft copolymer. The acrylic resin (2) showed the same polymerization behavior as the acrylic resin (1).

  It can be seen that the acrylic resin (2) is produced by living radical polymerization. The acrylic resin (2) had a heating residue of 50.3%, an acid value of 4.0 mgKOH, and a number average molecular weight of 150,000.

[Manufacture of acrylic resin (3)]
400 g of ethyl acetate / n-propyl acetate (= 50/50) was charged as a polymerization solvent into a 1-liter four-necked flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  While the bubbling of nitrogen gas was continued, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine was charged to the flask in an amount of 0.4% by weight of the mixed monomer, and dissolved uniformly. If dissolution is possible, benzoyl peroxide is charged in an equimolar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and the temperature rise is started. The temperature was raised to 80 ° C. in 30 minutes, and then the temperature was maintained at 80 ° C.

  2-ethylhexyl methacrylate / n-butyl acrylate / “β-CEA” / “Aron Macromer AA-6” / 2-hydroxyethyl methacrylate (= 5/86/1/3/5) mixed monomer (“Aron 400 g of Tg excluding “Macromer AA-6” was −45 ° C.) was dropped into the flask in 2 hours. After completion of dropping, polymerization was performed for 4 hours, and then cooled to room temperature to obtain acrylic resin (3). Manufactured. The acrylic resin (3) is composed of a polymer composed of 2-ethylhexyl methacrylate / n-butyl acrylate / “β-CEA” / 2-hydroxyethyl methacrylate and a polymer portion of “Aron Macromer AA-6” ( It is a graft copolymer using polymethyl methacrylate) as a branch polymer. FIG. 2 shows the polymerization behavior of the acrylic resin (3).

  It can be seen that the acrylic resin (3) is produced by living radical polymerization. The heating residue of the acrylic resin (3) was 50.2%, the acid value was 3.8 mgKOH, the hydroxyl value was 21.6 mgKOH, and the number average molecular weight was 120,000.

[Manufacture of acrylic resin (4)]
400 g of ethyl acetate / n-propyl acetate (= 50/50) was charged as a polymerization solvent into a 1-liter four-necked flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  While the bubbling of nitrogen gas was continued, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine was charged to the flask in an amount of 0.4% by weight of the mixed monomer, and dissolved uniformly. If dissolution is possible, benzoyl peroxide is charged in an equimolar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and the temperature rise is started. The temperature was raised to 80 ° C. in 30 minutes, and then the temperature was maintained at 80 ° C.

  400 g of a mixed monomer (Tg = −48 ° C.) of 2-ethylhexyl methacrylate / n-butyl acrylate / methacrylic acid / “Aron Macromer AA-6” (= 5/91/1/3) was placed in the flask in 2 hours. After dropping, polymerization was performed for 4 hours after completion of dropping, and then cooled to room temperature to produce an acrylic resin (4).

  The acrylic resin (4) is a polymer composed of 2-ethylhexyl methacrylate / n-butyl acrylate / methacrylic acid obtained by copolymerizing only one raw material (methacrylic acid) of the acidic functional group-containing monomer mixture, It is a graft copolymer having a polymer part (polymethyl methacrylate) of “Aron Macromer AA-6” as a branch polymer.

  The heating residue of the acrylic resin (4) was 50.2%, the acid value was 6.5 mgKOH, and the number average molecular weight was 120,000.

[Manufacture of acrylic resin (5)]
400 g of ethyl acetate / n-propyl acetate (= 50/50) was charged as a polymerization solvent into a 1-liter four-necked flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, the oxygen concentration in the flask was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.), and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  While the bubbling of nitrogen gas was continued, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine was charged to the flask in an amount of 0.4% by weight of the mixed monomer, and dissolved uniformly. If dissolution is possible, benzoyl peroxide is charged in an equimolar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and the temperature rise is started. The temperature was raised to 80 ° C. in 30 minutes, and then the temperature was maintained at 80 ° C.

  400 g of mixed monomer (Tg = −45 ° C.) of 2-ethylhexyl methacrylate / n-butyl acrylate / 2-hydroxyethyl methacrylate / “Aron Macromer AA-6” (= 5/87/5/3) for 2 hours The mixture was dropped into the flask and polymerized for 4 hours after completion of the dropping, and then cooled to room temperature to produce an acrylic resin (6).

Acrylic resin (5) is based on a polymer consisting of 2-ethylhexyl methacrylate / n-butyl acrylate / 2-hydroxyethyl methacrylate, which is not copolymerized with an acidic functional group-containing monomer mixture. It is a graft copolymer having a polymer part (polymethyl methacrylate) of AA-6 "as a branch polymer.
The heating residue of the acrylic resin (5) was 50.5%, and the number average molecular weight was 120,000.

Example 1
Acrylic resin (1) is blended with 20 phr of “YS Polystar TH-130” (hydrogenated terpene phenol resin, product of Yasuhara Chemical Co., Ltd.), and further dissolved with toluene so that the heating residue is 30%. Stirring was performed until the adhesive (1) was produced. The rheology measurement result of the adhesive (1) is shown in FIG. As shown in FIG. 3, the adhesive (1) had an appropriate thixotropy.

  The adhesive (1) was applied to “Lumirror T-60-100” (PET film manufactured by Toray Industries, Inc., transparent grade) to a dry film thickness of 25 μm, and dried at 100 ° C. for 1 minute. “Therapeutic WD # 50” (release film of Toray Film Processing Co., Ltd.) was affixed to the adhesive surface and aged at 23 ° C. for 1 week. One week later, the release film was peeled off, and the adhesive surface was pressure-bonded to a glass substrate with a load of 2 kg, and then allowed to stand for 1 hour, and the adhesive strength was measured by a 180 ° peel test using Tensilon. The results are shown in Table 1.

  Moreover, after measuring the light transmittance and haze using the test piece bonded to the glass substrate, a moisture and heat resistance test was performed. The results are shown in Table 1.

Example 2
Acrylic resin (2) was blended with 20 phr of “YS Polystar TH-130”, further diluted with toluene so that the heating residue was 30%, and stirred until it was uniformly dissolved to produce adhesive (2). . Adhesive (2) exhibited rheological properties similar to adhesive (1).

  The adhesive (2) was applied to “Lumirror T-60-100” so that the dry film thickness was 25 μm, and dried at 100 ° C. for 1 minute. “Therapy WD # 50” was affixed to the adhesive surface and aged at 23 ° C. for 1 week. One week later, the release film was peeled off, and the adhesive surface was pressure-bonded to a glass substrate with a load of 2 kg, and then allowed to stand for 1 hour, and the adhesive strength was measured by a 180 ° peel test using Tensilon. The test results are shown in Table 1.

  Moreover, after measuring the light transmittance and haze using the test piece bonded to the glass substrate, a moisture and heat resistance test was performed. The results are shown in Table 1.

Example 3
The acrylic resin (3) was diluted with toluene so that the heating residue was 40%, and “YS Polystar TH-130” was blended in 20 phr, followed by stirring until evenly dissolved. Next, isophorone diisocyanate was blended and mixed well as a curing agent so that the NCO index was 1.0. After measuring the heating residue, toluene was added to adjust the heating residue to 30% to produce an adhesive (3).

  The rheological measurement result of the adhesive (3) is shown in FIG. As shown in FIG. 4, the adhesive (3) had an appropriate thixotropic property.

  The adhesive (3) was applied to “Lumirror T-60-100” so as to have a dry film thickness of 25 μm, and dried at 100 ° C. for 1 minute. “Therapy WD # 50” was affixed to the adhesive surface and aged at 23 ° C. for 1 week. One week later, the release film was peeled off, and the adhesive surface was pressure-bonded to a glass substrate with a load of 2 kg. The test results are shown in Table 1.

  Moreover, after measuring the light transmittance and haze using the test piece bonded to the glass substrate, a moisture and heat resistance test was performed. The results are shown in Table 1.

  Adhesive (3), copper mesh (copper mesh line width 10 μm, line spacing 250 μm, line thickness 10 μm) (a copper mesh provided on the PET film via an adhesive, for example, plasma manufactured by Nippon Filcon An electromagnetic wave shielding mesh for display (hereinafter also referred to as copper mesh) was applied with a bar coater so that the dry film thickness was 25 μm, and dried at 100 ° C. for 1 minute. “Therapy WD # 50” was affixed to the adhesive surface and aged at 23 ° C. for 1 week. However, the total light transmittance was 83.0%, and the haze was 2.8. The copper mesh sheet to which the adhesive (3) was applied had high transparency as an FPD electromagnetic wave shielding sheet (EMI sheet).

  When the penetration state of the adhesive (3) into the copper mesh, the presence or absence of air bubbles, and the smoothness of the pressure-sensitive adhesive surface were observed with "Digital Microscope KH-3000VD" (Calto camera type digital microscope of Maruto Corporation), Adhesive (3) penetrated every corner of the copper mesh, and no bubbles were observed. Moreover, the pressure-sensitive adhesive surface was smooth, and the uneven profile of the copper mesh adhesive was completely restored. Since the adhesive (3) has an appropriate thixotropy, an EMI sheet excellent in the permeability to the copper mesh and the surface smoothness was produced.

  As seen in Table 1, the adhesive (1), the adhesive (2), and the adhesive (3) had moderate and good tackiness on the glass substrate as the FPD functional filter. Further, even after the heat and humidity resistance test, the same adhesiveness and transparency were exhibited as before the test.

Comparative Example 1
Acrylic resin (4) was blended with 20 phr of “YS Polystar TH-130”, further diluted with toluene so that the heating residue was 30%, and stirred until it was uniformly dissolved to produce adhesive (4). . The rheology of the adhesive (4) was similar to that of the adhesive (1) and had appropriate thixotropy.

  The adhesive (4) was applied to “Lumirror T-60-100” so that the dry film thickness was 25 μm, and dried at 100 ° C. for 1 minute. “Therapy WD # 50” was affixed to the adhesive surface and aged at 23 ° C. for 1 week. One week later, the release film was peeled off, and the adhesive surface was pressure-bonded to a glass substrate with a load of 2 kg, and then allowed to stand for 1 hour, and the adhesive strength was measured by a 180 ° peel test using Tensilon. The results are shown in Table 2.

  Moreover, after measuring the light transmittance and haze using the test piece bonded to the glass substrate, a moisture and heat resistance test was performed. The results are shown in Table 2.

Comparative Example 2
The acrylic resin (5) was diluted with toluene so that the heating residue was 40%, 20 phr of “YS Polystar TH-130” was blended, and the mixture was stirred until evenly dissolved. Next, isophorone diisocyanate was blended and mixed well as a curing agent so that the NCO index was 1.0. After measuring the heating residue, toluene was added to adjust the heating residue to 30% to produce an adhesive (5).

  The adhesive (5) was applied to “Lumirror T-60-100” so as to have a dry film thickness of 25 μm, and dried at 100 ° C. for 1 minute. “Therapy WD # 50” was affixed to the adhesive surface and aged at 23 ° C. for 1 week. One week later, the release film was peeled off, and the adhesive surface was pressure-bonded to a glass substrate with a load of 2 kg, and then allowed to stand for 1 hour, and the adhesive strength was measured by a 180 ° peel test using Tensilon. The test results are shown in Table 2.

  Moreover, after measuring the light transmittance and haze using the test piece bonded to the glass substrate, a moisture and heat resistance test was performed. The results are shown in Table 2.

FIG. 1 is a diagram showing the polymerization behavior of the acrylic resin (1). FIG. 2 is a diagram showing the polymerization behavior of the acrylic resin (3). FIG. 3 is a diagram showing the rheological measurement results of the adhesive (1). FIG. 4 is a diagram showing the rheological measurement results of the adhesive (3).

Claims (4)

An acrylic copolymer (A) having a unit represented by the following general formula in the molecular chain as a backbone polymer,

(Here, R1 is a hydrogen atom or a methyl group, and m is two or more different values selected from 0 or an integer of 1 to 5.)
An acrylic copolymer (B) having a unit represented by the following general formula in the molecular chain is used as a branch polymer.

(Here, R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 1 to 12 carbon atoms.)
An adhesive composition comprising an acrylic resin (C) having a number average molecular weight of 2 to 500,000.   The adhesive composition according to claim 1, wherein the adhesive composition contains an acrylic resin (C) having a hydroxyl value of 10 to 60 mgKOH, an acid value of 1 to 50 mgKOH, and a polyisocyanate compound.   Furthermore, the adhesive composition of Claim 1 or 2 with which a tackifier is mix | blended.   The adhesive composition according to any one of claims 1 to 3, which is used for joining a front functional filter of a flat panel display.

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