JP2007332276A - Adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a functional adhesive that exhibits excellent sticking and adhesion property to organic polymer compounds such as a PET film and metals such as aluminum, copper, and iron, and at the same time, is provided with heterofunction by having detachability from glass. <P>SOLUTION: The adhesive composition has a contact angle of 50-100°C against copper at 23°C when a heating residue is 35-55 wt.%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pressure-sensitive adhesive composition having good adhesiveness and adhesiveness to various substrates. In particular, the present invention has good adhesion and adhesion to organic polymer compounds such as PET film, and metals such as aluminum, copper and iron, and simultaneously provided with different functions having removability to glass. It relates to a functional adhesive.

  The pressure-sensitive adhesive composition of the present invention is particularly suitably used as a pressure-sensitive adhesive for flat panel display (FPD) functional filters.

  Acrylic copolymers are widely used for pressure-sensitive adhesives because they are excellent in weather resistance and transparency and easy to adjust physical properties. In recent years, the production of pressure-sensitive adhesives for display function filters has been increasing, supported by vigorous demand for FPDs and production expansion.

  A pressure-sensitive adhesive composition, which is a material for forming a pressure-sensitive adhesive layer provided on a PDP filter body, 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 pressure-sensitive adhesive that can adjust reworkability without impairing durability has been proposed. (See Patent Document 2). The technique proposed in Patent Document 2 is a (meth) acrylic acid ester copolymer (A) having a weight average molecular weight of 400,000 to 2.5 million and a (meth) acrylic acid ester copolymer having a weight average molecular weight of 1,000 to 50,000. It consists of a coalescence (B) and is (A) / (B) = 0.5-20 (weight blending ratio). Since the proposed technology contains a relatively large amount of low molecular weight polymer, there is a concern about reworkability. Furthermore, when the temperature of the base material to which the adhesive is applied is 3,40 ° C., there is a concern about adhesive residue and stringing. In addition, the (meth) acrylic acid ester copolymer (A), which seems to be capable of reworking, has a large molecular weight, so coating workability is poor and a large amount of organic solvent is required to dilute to a viscosity suitable for coating. In addition, the amount of discharged solvent is increased, which is not environmentally preferable.

  Transparency for filling or covering the openings of the mesh-like conductive member, which is a component of the thin electromagnetic wave shield laminate for displays, or the openings and the surface layer with a transparent resin composition that satisfies specific optical requirements A technique related to a resin composition has been proposed (see Patent Document 3). In the technique proposed in Patent Document 3, a hot melt adhesive is used as an adhesive (corresponding to a transparent resin composition in the proposed technique), and the hot melt adhesive is an ethylene / vinyl acetate copolymer, ethylene / Acrylic ester copolymers are preferred. As is well known, ethylene / vinyl acetate copolymers and ethylene / acrylic acid ester copolymers are derived from ethylene and have crystallinity, and the coating tends to become cloudy depending on the heat treatment method and the method of pressure bonding to the conductive mesh. There were drawbacks. As a result, the light transmittance of the electromagnetic wave shielding film is lowered, the haze is increased and the sharpness of the image is greatly lowered, and there is a problem that is difficult to use in display applications. Furthermore, according to the technical document (Non-Patent Document 1) relating to the method for manufacturing an electromagnetic wave shielding film for PDP, it is extremely difficult to manufacture the electromagnetic wave shielding film with the technique proposed in Patent Document 3, which increases the manufacturing cost. It was.

  A method for manufacturing a display film having electromagnetic shielding properties has been proposed. (See Patent Document 4) The technique proposed in Patent Document 4 is a method of bonding a metal foil of a conductive material having a roughened bonding surface to an adhesive layer through an adhesive layer on a transparent plastic substrate. The rough surface shape of the bonding surface of the metal foil is transferred to the adhesive layer, and the bonded metal foil has 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. A refractive index difference between the step of forming a geometric figure made of a metal foil and a portion to which the rough surface shape of the adhesive layer including the geometric figure formed by removing the metal foil is transferred is 0.14. It is related with the manufacturing method of the film for displays which has the electromagnetic shielding property characterized by including the process of coat | covering with the adhesive agent which is the following. As shown in Patent Document 4, 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 transmission property) 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. To this end, if explained based on the technique proposed in Patent Document 4, 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 completely penetrates into a small vessel made of a conductive material (for example, copper) (a cage surrounded by a geometric figure). It is extremely important that no gaps or bubbles remain in the vessel.

  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 4 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 4, 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 4, 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 4, it is considered that a small difference in refractive index is important, and the correspondence is limited only to eliminating refraction. As the adhesive that covers the rough surface profile does not trace, the adhesive is diluted with an organic solvent, so it is inevitable to trace the unevenness of the substrate as the volume shrinks during drying. It is not removed. The fact that the adhesive completely penetrates into a minute vessel made of a conductive material (for example, copper) and no gaps or bubbles remain in the vessel is disclosed in claim 1 of Patent Document 4. As described above, the technique of Patent Document 4 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 4 discloses does not have the capability to osmose | permeate in the container on the recessed part which an electroconductive substance forms.

  In Patent Document 4, the results of applying this technology to a practical copper mesh (line width (about 10 μm), line interval (about 250 μm), line thickness (about 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 covering the rough surface profile does not trace, and the adhesive is perfectly contained in a small container made of conductive material (eg copper) There was a strong desire to penetrate and leave no gaps or bubbles 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 JP 2004-256599 A JP 2004-140283 A 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., [May 30, 2006 search], Internet <URL: 1150341369062_0.html>

A functional pressure-sensitive adhesive that exhibits good adhesion and adhesion to organic polymer compounds such as PET film and metals such as aluminum, copper, and iron, and has different functions simultaneously with removability to glass is obtained. .

  This invention provides the adhesive composition whose contact angle with respect to copper in 23 degreeC is 50 degrees-100 degrees, when a heating residue is 35 to 55 weight%.

  The pressure-sensitive adhesive composition of the present invention strictly controls the contact angle of the pressure-sensitive adhesive with respect to copper, and controls the rheology of the pressure-sensitive adhesive, thereby providing excellent pressure-sensitive adhesiveness, rework pressure-sensitive adhesiveness, temporal stability of pressure-sensitive adhesiveness, moisture and heat resistance, Demonstrate heat resistance and UV protection.

  The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive that exhibits outstanding performance especially in terms of permeability to conductive mesh, transparency, and haze reduction, and is optimal for display applications. The pressure-sensitive adhesive composition of the present invention is particularly preferably used as a pressure-sensitive adhesive for FPD functional filters.

  This invention is an adhesive composition whose contact angle with respect to copper is 50 degrees-100 degrees (23 degreeC), when a heating residue is 35 to 55 weight%.

  The heating residue is measured according to JIS K 5400 (1997). The contact angle with respect to copper was measured at 23 ° C. by “FACE CONTACT-ANGLE METER CA-DT” manufactured by Kyowa Interface Chemical Co., Ltd.

  It is a very important requirement to strictly define the contact angle to copper. When the heating residue is 35 to 55% by weight and the contact angle to copper at 23 ° C. is 50 ° to 100 °, the adhesive easily penetrates into the conductive mesh material, and further, the visible light transmittance, Haze does not deteriorate.

  When the heating residue is 35 to 55% by weight and the contact angle to copper at 23 ° C. is less than 50 °, the rough surface profile of the substrate to which the conductive mesh material is bonded can be sufficiently repaired. However, the pressure-sensitive adhesive surface is roughened by the influence of the substrate profile, light is refracted and scattered on the pressure-sensitive adhesive surface, and the visible light transmittance and haze deteriorate.

  When the heating residue is 35 to 55% by weight, when the contact angle with respect to copper at 23 ° C. exceeds 100 °, the wettability with respect to the substrate is lowered, and the adhesiveness and adhesion to the substrate are deteriorated.

  Moreover, when the substrate is a substrate other than the conductive mesh material, such as a PET film, when the heating residue is 35 to 55% by weight and the contact angle to copper at 23 ° C. is lower than 50 °, , The substrate is easily affected by scratches on the substrate, and the surface smoothness (leveling property) is lowered and haze is increased. On the contrary, when the heating residue is 35 to 55% by weight, when the contact angle with respect to copper at 23 ° C. is higher than 100 °, the wettability to the substrate is lowered, and the adhesiveness and adhesion to the substrate are deteriorated. To do.

  When the heating residue is 35 to 55% by weight, the contact angle with respect to copper at 23 ° C is preferably 55 ° to 98 °, and more preferably 60 ° to 95 °.

In the pressure-sensitive adhesive composition of the present invention, when the heating residue is 35 to 55% by weight, the pressure-sensitive adhesive is preferably a thixotropic fluid at a shear rate of 10 ⁰ to 10 ³ s ⁻¹ .

  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
Strictly defining the rheology of adhesives, especially the flow properties, is a very important requirement in designing self-leveling properties and self-structuring of adhesives.

  As a result of diligent research, the present inventors have made the adhesive preferably a thixotropic fluid, so that the adhesive exhibits self-leveling and self-structuring functions, and scratches on the substrate on which the adhesive is applied, It has been found that defects such as dirt and irregularities are completely repaired, the pressure-sensitive adhesive surface is smooth, visible light transmittance is improved, and haze is lowered.

  Surprisingly, by using the pressure-sensitive adhesive as a thixotropic fluid, this excellent self-leveling property and self-structuring function can be expressed even in a solution in which the pressure-sensitive adhesive is diluted with a solvent. This effect is easily clarified by studying in comparison with Patent Document 4. That is, in Patent Document 4, since the pressure-sensitive adhesive (adhesive) is in the form of a solution diluted with a solvent, it is directly affected by the unevenness of the substrate, and the visible light transmittance is at most about 70%. The preferred pressure-sensitive adhesive composition completely repairs the unevenness of the substrate due to excellent self-leveling property and self-structuring function, and exhibits a visible light transmittance of at least 80%.

  Furthermore, when the base material to which the adhesive is applied is a conductive mesh material, the adhesive that does not have thixotropy does not penetrate uniformly into the mesh, and the visible light transmittance and haze tend to deteriorate. By contrast, the pressure-sensitive adhesive is a thixotropic fluid, allowing the pressure-sensitive adhesive to penetrate into the mesh quickly and evenly, without bubbles and defects, and with high visible light transmittance and low haze. A shield film can be manufactured.

  Similarly, this effect can be easily clarified by studying in comparison with Patent Document 4. That is, in Patent Document 4, although the pressure-sensitive adhesive (adhesive) is diluted with a solvent and is in the form of a solution that seems to have good permeability, the pressure-sensitive adhesive (adhesive) does not have thixotropic properties. Since the permeability to the conductive mesh is poor, the film is highly opaque as an optical film, and the visible light transmittance is only about 70%.

  The rheology of paints and adhesives is generally evaluated, considered, and judged in analog form based on the graph of the measurement results. If this is intentionally digitized, in the present invention, the thixotropic flow of the pressure-sensitive adhesive can be expressed by the relationship described below.

That is, if the viscosity when the shear rate is 5.5 ± 0.5 s ⁻¹ is Pa and the viscosity when the shear rate is 550 ± 50 s ⁻¹ is Pb, the relationship between Pa and Pb is Pa The value of / Pb is preferably 1.03 to 8.00, more preferably 1.05 to 6.00, still more preferably 1.23 to 5.55, and the best relationship between Pa and Pb Is 2.03-5.05. When the value of Pa / Pb is less than 1.03, the self-leveling property and the self-structure forming ability of the pressure-sensitive adhesive are insufficient, so that a uniform and smooth pressure-sensitive adhesive film may not be obtained. Moreover, the tendency for the permeability to an electroconductive mesh to be inferior is seen, and manufacture of an electroconductive mesh film with high transparency may become difficult. When the value of Pa / Pb exceeds 8.00, the thixotropy of the pressure-sensitive adhesive is too strong, and there is a tendency that defects such as stripes and rolls are likely to occur in the pressure-sensitive adhesive application process.

  The pressure-sensitive adhesive composition of the present invention preferably contains an acrylic resin for pressure-sensitive adhesives having a number average molecular weight of 3 to 500,000.

  In the present invention, the number average molecular weight of the acrylic resin was measured by GPC using “Polymethyl methacrylate Polymer Standard” manufactured by Polymer Laboratories as a molecular weight standard.

  The pressure-sensitive adhesive composition of the present invention preferably contains an acrylic resin for pressure-sensitive adhesives having a number average molecular weight (hereinafter referred to as Mn) of 3 to 500,000, more preferably for pressure-sensitive adhesives having a number average molecular weight of 4 to 300,000. An acrylic resin is included, More preferably, the acrylic resin for adhesives of a number average molecular weight 55-250,000 is included. When the Mn of the acrylic resin is less than 30,000, the cohesive force of the acrylic resin is weak, and adhesive tendency and stringing are likely to occur, and the reworkability tends to deteriorate. When the Mn of the acrylic resin exceeds 500,000, the viscosity of the pressure-sensitive adhesive becomes so high that it is necessary to dilute with a large amount of solvent in order to improve the coating workability. There is a tendency that it is easy to pick up defects of the base such as irregularities and scratches on the surface of the agent.

  The acrylic resin preferably used in the pressure-sensitive adhesive composition of the present invention is produced by radical polymerization of a (meth) acrylic acid ester monomer. Examples of the radical polymerization method include bulk polymerization, suspension polymerization, solution polymerization, emulsion polymerization, precipitation polymerization and the like, but the acrylic resin preferably used in the pressure-sensitive adhesive composition of the present invention can be produced by any method. May be. From the viewpoint of ease of use as an adhesive and handling, it is recommended that the acrylic resin be produced by solution polymerization in the adhesive composition of the present invention.

  Examples of the (meth) acrylate monomer constituting the acrylic resin preferably used in the pressure-sensitive adhesive composition of the present invention include methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, and acrylic. Cyclohexyl acid, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, dicyclopentanyloxyacrylate, dicyclopentenyloxyacrylate, 2,2,2-trifluoroethyl acrylate, methyl methacrylate, Ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, dicyclopentanyloxy methacrylate, dicyclo Nthenyloxy methacrylate, dicyclopentenyloxyethyl methacrylate, 2,2,2-trifluoroethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxy methacrylate Ethyl, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, acrylic acid, methacrylic acid, glycidyl acrylate, glycidyl methacrylate, methyl glycidyl methacrylate, 3,4-epoxycyclohexylmethyl methacrylate, γ-methacryloxypropyltri Examples include methoxysilane and γ-methacryloxypropyltriethoxysilane. The (meth) acrylic acid ester monomer may be used alone or as a mixture of two or more.

  At the same time, radically polymerizable monomers that can be copolymerized with (meth) acrylic acid ester monomers such as styrene and α-methylstyrene can be used in combination.

  Among the (meth) acrylic acid ester monomers, the glass transition temperature (hereinafter also referred to as Tg) of the homopolymer is preferably 30 ° C. or lower, more preferably 20 ° C. or lower, and further preferably 0 ° C. or lower. It is recommended that the acrylate monomer be copolymerized, preferably 50% by weight or more, more preferably 60% by weight or more, and still more preferably 80% by weight or more. Here, as the glass transition temperature of the homopolymer, a catalog value issued by a (meth) acrylic acid ester monomer sales company such as Toagosei Co., Ltd. or Nippon Shokubai Chemical Co., Ltd. was adopted.

  In the pressure-sensitive adhesive composition of the present invention, an acrylic acid ester monomer having a Tg of less than 50 ° C., for example, n-butyl acrylate, is preferably used for the (meth) acrylic acid ester monomer constituting the acrylic resin preferably used. When the polymerization amount is less than 50% by weight, the adhesive strength of the adhesive may be insufficient, and a sufficient function as the adhesive may not be exhibited. In addition, when a sheet-like product in which a pressure-sensitive adhesive is applied to a PET film or the like is wound into a coil shape, the adhesive film may be cracked or peeled off.

  The organic solvent used when the acrylic resin preferably used in the pressure-sensitive adhesive composition of the present invention is produced by solution polymerization includes toluene, xylene, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, methyl alcohol, ethyl Alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclohexanone, cyclohexane, heptane, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol, diethylene glycol, triethylene glycol, Propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, glycerin, phytanetriol, 1-hex 3-methylimidazolium hexafluorophosphate, glycidol, bisphenol A type epoxy resin, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexyl) adipate, 3- Examples include ethyl-3-hydroxymethyl oxetane, xylylene oxetane, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, and the like. These organic solvents may be used alone or as a mixture of two or more.

  In the pressure-sensitive adhesive composition of the present invention, as the organic solvent, it is recommended to avoid a solvent having a large chain transfer constant such as toluene or xylene, and to select a solvent having a smaller chain transfer constant such as butyl acetate. . When the chain transfer constant of the solvent is large, the chain transfer of the solvent to the polymer terminal radical cannot be ignored, and the target acrylic resin may not be produced.

  In the case of producing an acrylic resin by solution polymerization, it is desirable to carry out the polymerization system in which an inert gas such as nitrogen gas, argon gas or helium gas is substituted. 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. In other words, the polymerization rate is remarkably slow, and there are cases where many polymers with a low degree of polymerization are generated due to telomerization due to oxygen, the cohesive strength of the acrylic resin is reduced, and there is a tendency for problems such as adhesive residue and stringing to occur. It can be seen.

  The acrylic resin preferably used in the pressure-sensitive adhesive composition of the present invention is preferably produced at a polymerization temperature of preferably 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 decrease, and the chain transfer to the solvent is activated, making it difficult to produce a polymer having a desired molecular weight and molecular weight distribution. There is a case.

  In the pressure-sensitive adhesive composition of the present invention, it is recommended that the composition preferably contains an organoalkoxysilane compound having an isocyanate group and an alkoxysilane group in the molecule as a curing agent.

  In the pressure-sensitive adhesive composition of the present invention, the organoalkoxysilane compound having an isocyanate group and an alkoxysilane group in the molecule preferably contained includes 3-isocyanatepropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanate. Examples include propylmethyldimethoxysilane. These organoalkoxysilane compounds having an isocyanate group and an alkoxysilane group in these molecules may be used alone or as a mixture of two or more.

  In the pressure-sensitive adhesive composition of the present invention, it is preferable that an organoalkoxysilane compound having an isocyanate group and an alkoxysilane group in the molecule is blended as a curing agent, so that the pressure-sensitive adhesive at high temperature and high humidity including storage of the pressure-sensitive adhesive is included. There is a tendency that the force (hereinafter sometimes referred to as “moisture and heat resistance”) is drastically improved. That is, by blending an organoalkoxysilane compound having an isocyanate group and an alkoxysilane group in the molecule, the alkoxysilane group is oriented on the surface of a substrate to which an adhesive is applied, such as a glass substrate, and further the substrate By reacting with the surface hydroxyl group, the adhesive exhibits necessary and sufficient adhesive strength without peeling or swelling of the adhesive even at high humidity. On the other hand, since the isocyanate group is integrated with the acrylic resin by an addition reaction, as a result, even if the acrylic resin is stored on the base material to which the adhesive is applied at high temperature and high humidity, or is attached to the base material and is attached to the base material at high temperature and high temperature. Even when exposed to a wet environment, it is extremely good and exhibits strong adhesive strength.

  In the pressure-sensitive adhesive composition of the present invention, the organoalkoxysilane compound having an isocyanate group and an alkoxysilane group in the molecule preferably contained is 100 wt.% Of acrylic resin when the pressure-sensitive adhesive composition of the present invention contains an acrylic resin. Preferably, it is 0.0001 to 5.0% by weight, more preferably 0.001 to 2.5% by weight, and still more preferably 0.005 to 1.2% by weight based on the part.

  When the compounding amount of the organoalkoxysilane compound having an isocyanate group and an alkoxysilane group in the molecule is less than 0.0001% by weight with respect to 100 parts by weight of the acrylic resin, the moisture and heat resistance is not improved as expected. There is. That is, although it improves to a level which does not have a problem in the short period of about 20 days, the improvement effect tends to become thin in the period beyond it. Furthermore, the addition reaction rate of the organoalkoxysilane compound having an isocyanate group and an alkoxysilane group in the molecule with the acrylic resin, the reaction rate with the base material is slow, and when aging for about one week, on the contrary, adhesive residue, stringing, etc. Bugs may be seen.

  When the organoalkoxysilane compound having an isocyanate group and an alkoxysilane group in the molecule is blended in an amount exceeding 5.0% by weight with respect to 100 parts by weight of the acrylic resin, the adhesive strength is remarkably lost or the film May tend to be brittle. Further, since the alkoxysilane group reacts gradually, alcohol accompanying hydrolysis and condensation of the alkoxysilane group is generated in the adhesive film, which becomes bubbles and turbidity is generated in the adhesive film, resulting in deterioration of haze. There is a case.

  In the pressure-sensitive adhesive composition of the present invention, the pressure-sensitive adhesive composition has an average primary particle size in order to impart ultraviolet absorbing performance to the pressure-sensitive adhesive composition and prevent deterioration due to ultraviolet exposure of the substrate to which the pressure-sensitive adhesive is applied. It is recommended to contain zinc oxide of 100 nm or less. Further, the purpose of blending zinc oxide is to increase the refractive index of the pressure-sensitive adhesive and minimize the difference in refractive index from the substrate on which the pressure-sensitive adhesive is applied or applied. This prevents light from being scattered, refracted or reflected at the interface between the base material and the pressure-sensitive adhesive, and tends to increase the visible light transmittance and greatly improve haze.

  As described in Patent Document 4, there is also a method of increasing the refractive index of the pressure-sensitive adhesive by blending only the organic polymer compound in the pressure-sensitive adhesive composition or the second organic additive in the organic polymer compound. (Or a method of reducing the difference in refractive index from the substrate) (Reference: Patent Document 4), organic polymer materials having a high refractive index generally have poor light resistance, and are extremely brittle in a thin film such as an adhesive. It has properties. Under the irradiation of ultraviolet rays that are harmful to the adhesive film or the substrate, it often discolors over time of use, and the concern about the occurrence of cracks cannot be wiped out. This method is therefore unsuitable for display applications.

  A large amount of zinc oxide is buried on the earth and is an inexpensive pigment. In the paint industry, it is widely used as an extender pigment under the name Zinc Hua. Ordinary zinc white has an average primary particle size as large as 1 μm or more, and although it is an extender, it is unsuitable for applications that require high transparency of the film and transparency to visible light.

  In the pressure-sensitive adhesive composition of the present invention, it is recommended that the average primary particle diameter of zinc oxide preferably contained is preferably 100 nm or less, more preferably 80 nm or less, and even more preferably 60 nm or less. When the average primary particle diameter exceeds 100 nm, the transparency and visible light transmittance of the pressure-sensitive adhesive may be remarkably deteriorated. Not suitable for display applications.

  In the pressure-sensitive adhesive composition of the present invention, zinc oxide whose particle surface has been subjected to inactivation treatment or lipophilic treatment with alumina, silica or the like is preferably used. When the deactivation treatment and the lipophilic treatment are not performed, a highly transparent pressure-sensitive adhesive may not be produced, and a pressure-sensitive adhesive having good storage stability may not be produced. Furthermore, when a polyisocyanate such as isophorone diisocyanate is blended as a curing agent in the pressure-sensitive adhesive composition of the present invention, a pot of pressure-sensitive adhesive is used when zinc oxide that has not been deactivated or oleophilicized is used. There is a tendency that life adjustment and adhesiveness adjustment become difficult.

  The dispersion of zinc oxide preferably used in the pressure-sensitive adhesive composition of the present invention is (1) using an appropriate pigment dispersant in an organic solvent such as ethyl acetate and toluene, and having a zinc oxide concentration of 10 to 50% by weight. Either a method of manufacturing as a paste in which zinc oxide is dispersed, or (2) a method of manufacturing as a mill base in which zinc oxide is dispersed in varnish at a zinc oxide concentration of 1 to 50% by weight using a dispersion resin is recommended. Is done. When an acrylic resin is used as the dispersion resin, the acrylic resin desirably has a hydroxyl group or a carboxyl group, and particularly when the acrylic resin is a carboxyl group, the acid value of the acrylic resin is preferably 0.02 to 50 mgKOH, More preferably, it is 0.5-30 mgKOH, More preferably, when it is 1.2-30 mgKOH, transparency and visible-light transmittance are excellent, and a low-haze adhesive can be manufactured. When the acid value is less than 0.02 mg KOH, the contribution to dispersibility and dispersion stability may not be observed so significantly. When the acid value exceeds 50 mgKOH, the dispersibility and dispersion stability are good, but the water resistance and wet heat resistance of the pressure-sensitive adhesive tend to deteriorate.

  The zinc oxide preferably used in the pressure-sensitive adhesive composition of the present invention uses the manufactured zinc oxide dispersion paste or mill base, and the zinc oxide concentration is preferably 1 to 50% by weight, more preferably 2 to 30% by weight, More preferably, it is desirable to add 3 to 20% by weight of the pressure-sensitive adhesive. If the zinc oxide concentration is less than 1% by weight, the ultraviolet ray absorbing performance in the pressure-sensitive adhesive layer may be insufficient, and the substrate may not be sufficiently protected. In addition, the refractive index of the pressure-sensitive adhesive cannot be increased so much and haze improvement may not be achieved. When the zinc oxide concentration exceeds 50% by weight, even if the pigment is dispersed well, a part of the zinc oxide is agglomerated and there is a tendency to form a dispersion in which several primary particles are agglomerated. As a result, even if the transparency of the pressure-sensitive adhesive is ensured, the haze tends to deteriorate.

  The most preferable zinc oxide concentration is recommended to be determined by experimenting so that the visible light transmittance at 550 nm is 80% or more and the ultraviolet transmittance at 380 nm is 60% or less when the dry film thickness of the adhesive is 25 ± 2 μm. Is done. At this time, the zinc oxide concentration is approximately 3 to 20% by weight.

  The acrylic resin preferably used in the pressure-sensitive adhesive composition of the present invention is preferably one obtained by radical copolymerization of at least one of a hydroxyl group-containing acrylic monomer and an epoxy group-containing acrylic monomer.

  The hydroxyl group of the acrylic resin preferably used in the pressure-sensitive adhesive composition of the present invention can be crosslinked and chain-extended with a polyisocyanate compound such as hexamethylene diisocyanate, xylylene diisocyanate, tolylene diisocyanate, and isophorone diisocyanate. Cohesive force and mechanical strength can be improved. As a result, reworkability is improved, and there is a tendency for adhesive residue and stringing to be improved. Moreover, the tendency which demonstrates very favorable adhesiveness with respect to specific base materials, such as PET film, is seen.

  The epoxy group of the acrylic resin preferably used in the pressure-sensitive adhesive composition of the present invention is an active hydrogen atom-containing compound such as terpene phenol resin, 1-amino-3-dimethylaminopropane, γ-aminopropyltriethoxysilane, and imidazole compound. It is possible to cross-link with, and like the hydroxyl group, the cohesive force and mechanical strength of the pressure-sensitive adhesive can be improved. As a result, reworkability is improved, and there is a tendency for adhesive residue and stringing to be improved. Furthermore, the tendency which exhibits very favorable adhesiveness with respect to specific base materials, such as glass, is seen.

  Examples of the hydroxyl group-containing acrylic monomer preferably used in the pressure-sensitive adhesive composition of the present invention include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, and methacrylic acid. Examples thereof include 2-hydroxypropyl and 4-hydroxybutyl methacrylate. The hydroxyl group-containing acrylic monomer may be used alone or as a mixture of two or more.

  The hydroxyl group-containing acrylic monomer has the effect of increasing the cohesive strength of the acrylic resin and improving the reworkability. Moreover, there exists an effect | action which improves the adhesiveness to base materials, such as PET film, by bridge | crosslinking with a urethane hardening | curing agent etc.

  The hydroxyl group-containing acrylic monomer preferably used in the pressure-sensitive adhesive composition of the present invention is preferably 0.2 to 20% by weight in the acrylic resin when the pressure-sensitive adhesive composition of the present invention contains an acrylic resin. More preferably, the copolymerization is desirably 2 to 15% by weight, and more preferably 3 to 10% by weight. When the copolymerization amount of the hydroxyl group-containing acrylic monomer is less than 0.2% by weight, the crosslinking density of the pressure-sensitive adhesive becomes too low, and adhesive remnants and stringing tend to occur and reworkability tends to deteriorate. It can be seen. When the copolymerization amount of the hydroxyl group-containing acrylic monomer exceeds 20% by weight, the crosslinking density tends to be too high and the tackiness tends to be lost.

  Examples of the epoxy group-containing acrylic monomer preferably used in the pressure-sensitive adhesive composition of the present invention include glycidyl acrylate, glycidyl methacrylate, methyl glycidyl methacrylate, and 3,4-epoxycyclohexylmethyl methacrylate. The epoxy group-containing acrylic monomer may be used alone or as a mixture of two or more. Among these epoxy group-containing acrylic monomers, the content of chlorine atoms and chlorine compounds as impurities is preferably 1000 ppm, more preferably 100 ppm or less. When the content of chlorine atoms and chlorine compounds exceeds 1000 ppm, there is a tendency that a large amount of low-polymerization polymer is formed by chain transfer reaction or telomerization, and adhesive residue and stringiness may be deteriorated.

  When an acrylic resin is contained in the pressure-sensitive adhesive composition of the present invention, the epoxy group-containing acrylic monomer is copolymerized in the acrylic resin, thereby greatly improving the adhesiveness with a conductive mesh material such as a copper mesh. It also has a function of strongly suppressing corrosion of the conductive mesh material due to oxidation or the like.

  When an acrylic resin is contained in the pressure-sensitive adhesive composition of the present invention, the epoxy group-containing acrylic monomer is preferably 0.02 to 30% by weight, more preferably 0.5 to 15 in the acrylic resin. It is desirable to copolymerize by weight, more preferably 5-12% by weight. When the copolymerization amount of the epoxy group-containing acrylic monomer is less than 0.02% by weight, the permeability of the adhesive to the conductive mesh tends to be lost. When the copolymerization amount of the epoxy group-containing acrylic monomer exceeds 30% by weight, there is a tendency that the crosslinking density becomes too high and the tackiness is lost.

  Examples of the carboxyl group-containing acrylic monomer preferably used in the pressure-sensitive adhesive composition of the present invention include acrylic acid, methacrylic acid, maleic acid and itaconic acid. The carboxyl group-containing acrylic monomer may be used alone or as a mixture of two kinds.

  As described above, the carboxyl group-containing acrylic monomer is a very effective acrylic monomer for improving pigment dispersibility such as zinc oxide. In addition, the cohesive strength of the acrylic resin is improved, and depending on the adhesiveness improvement and the amount of copolymerization, there is a tendency to be effective in improving the water resistance.

  The carboxyl group-containing acrylic monomer is preferably copolymerized so that the acid value of the acrylic resin is preferably 0.02 to 50 mgKOH, more preferably 0.5 to 30 mgKOH, and even more preferably 1.2 to 30 mgKOH. . At this time, an adhesive having excellent transparency and visible light transmittance and low haze can be produced. When the acid value of the acrylic resin is less than 0.02 mg KOH, the contribution to dispersibility and dispersion stability may not be observed so significantly. When the acid value exceeds 50 mgKOH, the dispersibility and dispersion stability are good, but the water resistance and wet heat resistance of the pressure-sensitive adhesive tend to deteriorate.

  The acrylic resin preferably used in the pressure-sensitive adhesive composition of the present invention comprises an acrylic copolymer segment (A) obtained by radical copolymerization of a hydroxyl group-containing acrylic monomer, an epoxy group-containing acrylic monomer or a carboxyl group-containing acrylic unit. Adhesive strength is improved when the polymer contains an AB block copolymer composed of an acrylic copolymer segment (B) that has been radically copolymerized, and in particular, an adhesive in which an adhesive is applied and a protective film is applied to the adhesive surface It is desirable because of its excellent adhesive strength retention during storage such as tape. Furthermore, when the acrylic resin preferably used in the pressure-sensitive adhesive composition of the present invention contains an AB block copolymer, there is a strong tendency for the permeability to the conductive mesh to be extremely excellent. At this time, the visible light transmittance of the conductive mesh film is improved and the haze tends to decrease.

  An acrylic copolymer segment (A) in which a hydroxyl group-containing acrylic monomer preferably used in the pressure-sensitive adhesive composition of the present invention is radically copolymerized, and an epoxy group-containing acrylic monomer or an acrylic in which a carboxyl group is radically copolymerized When the AB block copolymer comprising the copolymer segment (B) is radically copolymerized using a reaction product of a hindered amine compound and an organic peroxide as a polymerization initiator, the above characteristics tend to become remarkable. Even more desirable.

  Below, an acrylic copolymer segment (A) in which a hydroxyl group-containing acrylic monomer is radically copolymerized, and an acrylic copolymer in which an epoxy group-containing acrylic monomer or a carboxyl group-containing acrylic monomer is radically copolymerized An example of the manufacturing method of the AB block copolymer which consists of a segment (B) is shown.

[Production Example of AB Block Copolymer]
A polymerization solvent (for example, butyl acetate) 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 the bubbling of nitrogen gas is continued, 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 90 ° C. in 30 minutes, and thereafter 90 ° C. is kept.

  A (meth) acrylic acid ester monomer constituting the acrylic copolymer segment (A), for example, a mixed monomer of n-butyl acrylate / 2-hydroxyethyl methacrylate, is dropped into the flask in 2 hours, and the dropping is completed. Thereafter, the polymerization reaction is carried out until a predetermined polymerization rate (for example, until the polymerization rate reaches 80%) while checking the polymerization rate and the number average molecular weight as needed.

  Next, a (meth) acrylic acid ester monomer constituting the acrylic copolymer segment (B), for example, a mixture of n-butyl acrylate / 2-ethylhexyl methacrylate / styrene / 2-hydroxyethyl methacrylate / glycidyl methacrylate The monomer is charged into the flask, and the polymerization reaction is continued until the polymerization rate reaches 100% while checking the polymerization rate and the number average molecular weight as needed.

  In this production method, the number average molecular weight increases as the polymerization rate increases during the production of the acrylic copolymer segment (A) and during the production of the acrylic copolymer segment (B). Furthermore, the number average molecular weight of the finally produced polymer exceeds the number average molecular weight of the acrylic copolymer segment (A).

That is, it is clear that both radical polymerization of the acrylic copolymer segment (A) and radical polymerization of the acrylic copolymer segment (B) proceed by living radical polymerization (LRP). It is clear that an AB block copolymer having a polymer segment (A) and an acrylic copolymer segment (B) in the same molecule is produced. (Reference: "Radical polymerization handbook = From basics to new developments", Mikiharu Tsunoike, Takeshi Endo, NTS, p102-p152 (1999))
As described above, an AB block copolymer having an acrylic copolymer segment (A) in which a hydroxyl group-containing acrylic monomer is copolymerized and an acrylic copolymer segment (B) in which an epoxy group-containing acrylic monomer is copolymerized. Can be manufactured.

  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 and the like are exemplified. The hindered amine compound may be used alone or as a mixture of two or more.

  The hindered amine compound is preferably 0.002 to 20.0 weights with respect to 100 weight parts of the (meth) acrylic acid ester monomer constituting the acrylic copolymer segment (A) or the acrylic copolymer segment (B). %, More preferably 0.005 to 15.0% by weight, 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 (meth) acrylate monomer constituting the acrylic copolymer segment (A) or the acrylic copolymer segment (B). In some cases, the polymerization rate is difficult to increase, and it takes a long time for the polymerization, which tends to lose practicality.

  The amount of hindered amine compound used exceeds 20.0% by weight based on 100 parts by weight of the (meth) acrylate monomer constituting the acrylic copolymer segment (A) or the acrylic copolymer segment (B). In some cases, the polymer may be colored, which may be a practical problem. Moreover, the tendency for the production | generation of AB block copolymer to be suppressed is seen.

  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 the block copolymer cannot be produced. There is a tendency for the molecular weight polymer to be formed in a large proportion.

  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. The reaction is an acid-base neutralization reaction and may involve a large exotherm. Therefore, it is preferable to carry out the reaction little by little while cooling the reaction system. More preferably, it is desirable to dilute in an organic solvent. When it is diluted with an organic solvent, no exotherm is observed, and the target reactant can be produced safely and reliably.

  The number average molecular weight (hereinafter also referred to as Mn) of the acrylic copolymer segment (A) is preferably 2 to 200,000, more preferably 3 to 150,000. When the Mn of the acrylic copolymer segment (A) is less than 20,000, the adhesive permeability to the conductive mesh may be deteriorated, and adhesive residue and stringing are likely to occur, resulting in poor reworkability. Tend to. When the Mn of the acrylic copolymer segment (A) exceeds 200,000, the pressure-sensitive adhesive has a high viscosity and the coating workability may be deteriorated. Moreover, adhesive force falls and sufficient adhesiveness may not be obtained.

  The acrylic copolymer segment (A) and the acrylic copolymer segment (B) are preferably 5 to 98 parts by weight, more preferably 10 to 10 parts by weight, with the total amount being 100 parts by weight. 90 parts by weight, more preferably 15 to 85 parts by weight is desirable. When the amount of the acrylic copolymer segment (B) is less than 5 parts by weight, the permeability of the adhesive to the conductive mesh tends to deteriorate, and the visible light transmittance and haze tend to deteriorate. . Moreover, the adhesiveness to an electroconductive mesh material may deteriorate, and the tendency for the corrosion resistance of a mesh material to deteriorate is seen. When the amount of the acrylic copolymer segment (B) exceeds 98 parts by weight, the pressure-sensitive adhesive tends to be tinted blue and transparency and haze tend to deteriorate.

  Most preferably, the amount of the acrylic copolymer segment (B) is any one of (1) 15 to 45 parts by weight and (2) 55 to 85 parts by weight. When it exists in this area | region, an adhesive becomes the most easy to osmose | permeate an electroconductive mesh, and manufacture of an electroconductive sheet with a high visible light transmittance and a small haze becomes easy.

  The Mn of the AB block copolymer comprising the acrylic copolymer segment (A) and the acrylic copolymer segment (B) is preferably 3 to 500,000, more preferably 3 to 300,000, and still more preferably 500 to 200,000. It is recommended that When the Mn of the AB block copolymer is less than 50,000, the cohesive force of the polymer is small, adhesive residue and stringiness tend to occur, and the reworkability tends to deteriorate. Moreover, there exists a tendency for heat-and-moisture resistance to deteriorate, and a coating film may whiten under high temperature and high humidity. When the Mn of the AB block copolymer exceeds 500,000, the viscosity of the pressure-sensitive adhesive becomes too high and the coating workability tends to deteriorate. In addition, the thixotropy of the pressure-sensitive adhesive tends to be too strong, and there is a tendency that unevenness and rolls are likely to appear on the coating film, making it difficult to form a uniform coating film.

  The pressure-sensitive adhesive composition according to the present invention includes an AB block copolymer to change the molecular weight, glass transition temperature, copolymerization ratio, type and amount of auxiliary materials to be blended, and the like. Can control the thixotropy of the adhesive, contact angle to the substrate, refractive index, etc., adjusting the adhesive strength, adjusting the rework adhesive strength, imparting shock absorption, and penetrating into the conductive mesh Improvement of transparency, transparency, reduction of haze, etc. can be adjusted arbitrarily. It is also easy to bring out the function of plus α by blending tackifier, plasticizer, ultraviolet absorber, HALS, silane coupling agent, urethane curing agent and the like.

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

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

  1) The polymerization rate was calculated from the heating residue (according to JIS K 5400-1997). The oxygen concentration of the polymerization system was measured with an oxygen concentration meter “XO-326ALA” (oxygen concentration meter of Shin Cosmos Electric Co., Ltd.).

  2) The number average molecular weight (Mn) was measured by GPC using “Polymethyl methacrylate Polymer Standard” manufactured by Polymer Laboratories as a molecular weight standard.

3) Contact angle is “FACE CONTACT-ANGLE” manufactured by Kyowa Interface Chemical Co., Ltd.
It measured at 23 degreeC by METER CA-DT.

  4) The rheology of the adhesive was measured at 25 ° C. using a “VAR-type 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.

  5) The average particle size of the pressure-sensitive adhesive in which zinc oxide was blended was measured by weight average using “Dense particle size analyzer FPAR-1000” manufactured by Otsuka Electronics.

  6) The acid value of the acrylic resin was measured according to JIS K 5400 (1997).

Example 1
Into a 2 liter four-necked flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device, 214.3 g of butyl acetate was charged as a polymerization solvent. Nitrogen gas was introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, it was confirmed that the oxygen concentration in the flask was less than 0.2 vol%.

  While the bubbling of nitrogen gas was continued, 0.84 g of 4-benzoyloxy-2,2,6,6-tetramethylpiperidine was added to the flask (0.40% by weight of the acrylic monomer mixture (a-1)). Charged and dissolved to be uniform. Next, 0.778 g of benzoyl peroxide (equal molar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine) was charged, and stirring was continued until the benzoyl peroxide dissolved and became a homogeneous solution. The temperature increase was started, the temperature was increased to 90 ° C. in 30 minutes, and the temperature was maintained at 90 ° C. below.

  Charge 500 g of acrylic monomer mixture (a-1) (n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate (= 90/5/5) into a container and use a constant flow pump. After dropping in the flask over 2 hours, the polymerization was continued until the polymerization rate (hereinafter also referred to as α) reached 0.80 while keeping the temperature at 90 ° C. (required about 10 hours) α = When 0.8, Mn was 82000. The relationship between α and Mn is shown in Fig. 1. It can be seen from Fig. 1 that this polymerization reaction proceeds by living radical polymerization.

  Acrylic monomer mixture (b-1) (n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate / styrene / glycidyl methacrylate) (= 70.1) /0.2/5.0/0.7/24.0) 71.4 g and butyl acetate 30.6 g were added, and polymerization was continued until α = 1.0, and an AB block copolymer (1 ) Was manufactured. The relationship between α and Mn (which required about 8 hours) is shown in FIG. FIG. 2 shows that the main polymerization reaction proceeds by living radical polymerization, and an AB block copolymer is formed (estimated A segment composition: n-butyl acrylate / 2-ethylhexyl methacrylate / methacrylic acid 2). -Hydroxyethyl = 90/5/5, estimated B segment composition: n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate / styrene / glycidyl methacrylate = 81.7 / 3/5/0. 3/10, A / B = 70/30).

  The produced block copolymer (1) had a heating residue of 70.2% and Mn = 18000.

  The block copolymer (1) was diluted with ethyl acetate so that the heating residue was 50%, and “YS Polystar TH-130” (hydrogenated terpene phenol resin, product of Yasuhara Chemical Co., Ltd.) was blended in 20 phr. Stirring was carried out until evenly dissolved. Next, isophorone diisocyanate may be blended as a curing agent so that the number of moles of NCO / number of moles of hydroxyl group of block copolymer (1) (hereinafter also referred to as NCO index) = 1/1 (NCO index 1.0). Mixed. After measuring the heating residue, ethyl acetate was added to adjust the heating residue to 40%. This was made into the adhesive (1).

The rheological measurement result of the pressure-sensitive adhesive (1) is shown in FIG. As shown in FIG. 3, the pressure-sensitive adhesive (1) had an appropriate thixotropic property. Viscosity Pa shear rate 5.61S ^-1 is 12.5Pas, viscosity Pb shear rate 562S ^-1 was 3.37 (Pa / Pb = 3.71) .

  Moreover, the contact angle (23 degreeC) with respect to the copper substrate of adhesive (1) was 82 degrees.

  The pressure-sensitive adhesive (1) was applied to “Lumirror T-60-100” (PET film, transparent grade, manufactured by Toray Industries, Inc.) so that the dry film thickness was 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 adhesive strength was as strong as 20 N / 25 mm. No adhesive remained on the glass plate, and the reworkability was good.

  Table 1 shows the results of pasting a release film on the adhesive surface and storing it at 23 ° C. and 80 ° C. for a predetermined date, and then pasting it on a glass substrate and measuring the adhesive strength. The adhesive strength was stable and excellent without changing over time or at a high temperature.

  Adhesive (1) is a 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 3.2. (Measured with a measuring instrument of Nippon Denshoku Industries Co., Ltd. “turbidity meter NDH 2000” based on the test method of JIS K 7361 and JIS K 7136.) The copper mesh sheet coated with the adhesive (1) is It had high transparency as a display film.

  The pressure-sensitive adhesive (1) had appropriate thixotropic properties as shown in FIG. Moreover, it had a sufficiently high contact angle to the copper substrate. For this reason, it is guessed that it is excellent in the permeability to a copper mesh, and the surface smoothness of an adhesive.

  When the penetration state of the adhesive (1) into the copper mesh, the presence or absence of air bubbles, and the smoothness of the adhesive surface were observed with "Digital Microscope KH-3000VD" (Calto camera type digital microscope of Maruto Co., Ltd.) The pressure-sensitive adhesive (1) penetrated to every corner of the 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 pressure-sensitive adhesive (1) has an appropriate thixotropy and a high contact angle with copper, it was excellent in the permeability to the copper mesh and the surface smoothness of the pressure-sensitive adhesive.

  The pressure-sensitive adhesive (1) 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. This pressure-sensitive adhesive-attached film was heated at 100 ° C. for 1 minute in a state where it was pressed against a copper mesh with a load of 2 kg. Thereafter, aging was performed at 23 ° C. for 1 week.

  The total light transmittance of the copper mesh sheet to which the pressure-sensitive adhesive (1) was transferred was 82.0%, and the haze was 4.1. The copper mesh sheet to which the pressure-sensitive adhesive (1) was transferred had high transparency as a display film. The adhesive (1) was excellent in permeability to the copper mesh both when applied directly to the copper mesh and when applied to the PET film and then transferred to the copper mesh.

Example 2
Into a 2 liter four-necked flask equipped with a nitrogen gas blowing tube, a temperature sensor, a condenser, and a stirring device, 214.3 g of butyl acetate was charged as a polymerization solvent. Nitrogen gas is introduced into the bottom of the flask and held for 30 minutes while bubbling. Thereafter, it was confirmed that the oxygen concentration in the flask was less than 0.2 vol%.

  While the bubbling of nitrogen gas was continued, 0.84 g of 4-benzoyloxy-2,2,6,6-tetramethylpiperidine (0.40% by weight of the acrylic monomer mixture (a-1)) was charged into the flask. And dissolved to be uniform. Next, 0.778 g of benzoyl peroxide (equal molar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine) was charged, and stirring was continued until the benzoyl peroxide dissolved and became a homogeneous solution. The temperature increase was started, the temperature was increased to 90 ° C. in 30 minutes, and the temperature was maintained at 90 ° C. below.

  Charge 500 g of acrylic monomer mixture (a-1) (n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate (= 90/5/5) into a container and use a constant flow pump. The solution was dropped into the flask in 2 hours, and then the polymerization was continued until the polymerization rate reached 0.80 while keeping the temperature at 90 ° C. (Required for about 10 hours) When α = 0.8, Mn was 82000. The relationship between α and Mn is shown in Fig. 1. It can be seen from Fig. 1 that this polymerization reaction proceeds by living radical polymerization.

  The acrylic monomer mixture (b-1) (n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate / methacrylic acid) (= 87.6 / 0. 2 / 5.0 / 7.2) 71.4 g and butyl acetate 30.6 g were added, and polymerization was continued until α = 1.0 to produce an AB block copolymer (2) (about 8 (Estimated A segment composition: n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate = 90/5/5, estimated B segment composition: n-butyl acrylate / methacrylic acid) 2-ethylhexyl / 2-hydroxyethyl methacrylate / methacrylic acid = 89/3/5/3, A / B = 70/30).

  The produced block copolymer (2) had a heating residue of 70.5% and Mn = 18000.

The block copolymer (2) was diluted with ethyl acetate so that the heating residue was 40%. To this was added “NANOFINE 50S-D” (Sakai Chemical's ultrafine zinc oxide, surface treatment (alumina, silica treatment), lipophilic zinc oxide, average primary particle size 20 nm) so that the PWC was 10%. DISPERON DA-7301 "(high molecular weight pigment dispersant from Enomoto Kasei) was added to 20% of zinc oxide. This was premixed with a disper for 30 minutes, and then zinc oxide was dispersed using “LABSTAR / MINI CER” (a pigment dispersing machine of Ashizawa Finetech Co., Ltd.).
Dispersion conditions were as follows: vessel material ZrO ₂ , rotor ZrO ₂ , media ZrO ₂ , media diameter 0.1 mm, media filling ratio 85%, peripheral speed 10 m / sec, and slurry was supplied at 300 ml / min using a diaphragm pump. . The temperature of the slurry during dispersion was adjusted (cooled) to 20 to 30 ° C.

  After completion of the dispersion, the mixture was diluted with ethyl acetate so as to have a solid content of 40%, and 20 phr of “YS Polystar TH-130” was mixed and stirred until it was uniformly dissolved. Next, isophorone diisocyanate was blended and mixed well as a curing agent so that the NCO index = 1/1. After measuring the heating residue, ethyl acetate was added to adjust the heating residue to 40%.

Viscosity Pa shear rate 5.61S ^-1 of the produced adhesive 20.2Pas, viscosity Pb shear rate 562S ^-1 was 4.05 (Pa / Pb = 4.99) .

  Moreover, the contact angle (23 degreeC) with respect to the copper substrate of an adhesive was 80 degrees.

  This pressure-sensitive adhesive containing ultrafine zinc oxide was applied to a copper mesh 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. The total light transmittance of the copper mesh sheet coated with the pressure-sensitive adhesive containing ultrafine zinc oxide was 82.1%, and the haze was 1.8. The copper mesh sheet coated with an adhesive containing ultrafine zinc oxide had high transparency as a display film. Since the primary particle diameter of zinc oxide is small and the pigment dispersion is appropriately performed, the visible light transmittance is maintained at a high level, and the improvement in haze is particularly remarkable.

  The pressure-sensitive adhesive containing ultrafine zinc oxide was applied to “Lumirror T-60-100” to 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 adhesive strength was as strong as 18 N / 25 mm. No adhesive remained on the glass plate and the reworkability was good.

  The light transmittance of the adhesive film was measured using “UV-2550” (a spectrophotometer manufactured by Shimadzu Corporation). The UV transmittance at 380 nm was 42%, and the visible light transmittance at 550 nm was 92.0%, which was excellent in UV blocking performance and visible light transparency.

Example 3
214.3 g of butyl acetate as a polymerization solvent was charged into a 3 liter four-necked 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, it was confirmed that the oxygen concentration in the flask was less than 0.2 vol%.

  While the bubbling of nitrogen gas was continued, 0.84 g of 4-benzoyloxy-2,2,6,6-tetramethylpiperidine (0.40% by weight of the acrylic monomer mixture (a-2)) was charged into the flask. And dissolved to be uniform. Next, 0.778 g of benzoyl peroxide (equal molar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine) was charged, and stirring was continued until the benzoyl peroxide dissolved and became a homogeneous solution. The temperature increase was started, the temperature was increased to 90 ° C. in 30 minutes, and the temperature was maintained at 90 ° C. below.

  Charge the acrylic monomer mixture (a-2) (n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate (= 90/5/5) into a container and use a constant flow pump. The solution was dropped into the flask in 2 hours, and then polymerization was continued until α was 0.80 while keeping 90 ° C. (required about 10 hours) When α = 0.8, Mn The relationship between α and Mn is shown in Fig. 1. It can be seen from Fig. 1 that this polymerization reaction proceeds by living radical polymerization.

  Acrylic monomer mixture (b-3) (n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate / styrene / glycidyl methacrylate) (= 80.7) /2.8/5.0/0.3/11.2) 833.3 g and 1690.4 g of butyl acetate were added, and polymerization was continued until α = 1.0, and an AB block copolymer (2 ) Was manufactured. The relationship between α and Mn (which required about 12 hours) is shown in FIG. FIG. 4 shows that the main polymerization reaction proceeds by living radical polymerization, and an AB block copolymer is formed (estimated A segment composition: n-butyl acrylate / 2-ethylhexyl methacrylate / methacrylic acid 2). -Hydroxyethyl = 90/5/5, estimated B segment composition: n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate / styrene / glycidyl methacrylate = 81.7 / 3/5/0. 3/10, A / B = 30/70).

  The produced block copolymer (3) had a heating residue of 70.5% and Mn = 109000.

  The block copolymer (2) is diluted with ethyl acetate so that the heating residue is 50%, 20 phr of “YS Polystar TH-130” is blended, and “Adekastab AO-330” (oxidation manufactured by Asahi Denka Co., Ltd.) (Inhibitor) was blended in 3 phr and stirred until dissolved uniformly. Next, isophorone diisocyanate was blended and mixed well as a curing agent so that NCO = 1.2 / 1. After measuring the heating residue, ethyl acetate was added to adjust the heating residue to 40%. This was made into the adhesive (2).

The rheological measurement result of the pressure-sensitive adhesive (2) is shown in FIG. As shown in FIG. 5, the pressure-sensitive adhesive (2) had an appropriate thixotropic property. Viscosity Pa shear rate 5.63S ^-1 is 12.9Pas, viscosity Pb shear rate 572S ^-1 was 4.28 (Pa / Pb = 3.01) .

  Moreover, the contact angle (23 degreeC) with respect to the copper substrate of an adhesive (2) was 85 degrees.

  The pressure-sensitive adhesive (2) 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 adhesive strength was as strong as 15 N / 25 mm, no adhesive remained on the glass plate, and the reworkability was good.

  The pressure-sensitive adhesive (2) was applied to a copper mesh with a bar coater 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. This product had a total light transmittance of 80.2% and a haze of 2.0. The copper mesh sheet coated with the pressure-sensitive adhesive (2) had high transparency as a display film.

Example 4
An AB block copolymer (4) was produced by the same polymerization method as in Example 1. That is, 214.3 g of butyl acetate as a polymerization solvent is charged into a 2-liter four-necked 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, it was confirmed that the oxygen concentration in the flask was less than 0.2 vol%.

  While the bubbling of nitrogen gas was continued, 0.84 g of 4-benzoyloxy-2,2,6,6-tetramethylpiperidine (0.40% by weight of the acrylic monomer mixture (a-3)) was charged into the flask. And dissolved to be uniform. Next, 0.778 g of benzoyl peroxide (equal molar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine) was charged, and stirring was continued until the benzoyl peroxide dissolved and became a homogeneous solution. The temperature increase was started, the temperature was increased to 90 ° C. in 30 minutes, and the temperature was maintained at 90 ° C. below.

Charge 500 g of acrylic monomer mixture (a-3) (n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate (= 90/5/5) into a container and use a constant flow pump. The solution was dropped into the flask in 2 hours, and then polymerization was continued until α was 0.80 while keeping 90 ° C. (required about 10 hours) When α = 0.8, Mn The relationship between α and Mn is shown in Fig. 1. It can be seen from Fig. 1 that this polymerization reaction proceeds by living radical polymerization.
Acrylic monomer mixture (b-4) (n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate / styrene / glycidyl methacrylate) (= 46.1), while maintaining 90 ° C. /0.2/5.0/0.7/48.0) 71.4 g and butyl acetate 30.6 g were added, and polymerization was continued until α = 1.0, and an AB block copolymer (4 ) Was manufactured. The relationship between α and Mn (which required about 8 hours) is shown in FIG. It can be seen from FIG. 6 that this polymerization reaction proceeds by living radical polymerization, and an AB block copolymer is formed (estimated A segment composition: n-butyl acrylate / 2-ethylhexyl methacrylate / methacrylic acid 2). -Hydroxyethyl = 90/5/5, estimated B segment composition: n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate / styrene / glycidyl methacrylate = 71.7 / 3/5/0. 3/20, A / B = 70/30).

  The produced block copolymer (4) had a heating residue of 70.3% and Mn = 12,000.

  The block copolymer (3) is diluted with ethyl acetate so that the heating residue is 50%, and 20 phr of “YS Polyster TH-130” and 2 phr of “Adeka Stab AO-330” are mixed and dissolved uniformly. Stir until. Next, IPDI was blended and mixed well as a curing agent so that NCO = 1/1. After measuring the heating residue, ethyl acetate was added to adjust the heating residue to 40%. This was designated as pressure-sensitive adhesive (3).

The rheological measurement result of the pressure-sensitive adhesive (3) is shown in FIG. As shown in FIG. 7, the pressure-sensitive adhesive (3) had an appropriate thixotropic property. Viscosity Pa shear rate 5.63S ^-1 is 5.13Pas, viscosity Pb shear rate 549S ^-1 was 2.14 (Pa / Pb = 2.40) .

  Moreover, the contact angle (23 degreeC) with respect to the copper substrate of an adhesive (3) was 80 degrees.

  The pressure-sensitive adhesive (3) was applied to “Lumirror T-60-100” to 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 adhesive strength was extremely strong at 25 N / 25 mm, and no adhesive remained on the glass plate, and the reworkability was good.

  The pressure-sensitive adhesive (3) was applied to a copper mesh with a bar coater 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. However, the total light transmittance was 82.6%, and the haze was 3.0. The copper mesh sheet coated with the pressure-sensitive adhesive (3) had high transparency as a display film.

  The pressure-sensitive adhesive (3) was further mixed with 0.5 phr of 3-isocyanatopropyltriethoxysilane to produce a pressure-sensitive adhesive (4).

  The pressure-sensitive adhesive (4) was applied to “Lumirror T-60-100” to 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 adhesive strength was extremely strong at 30 N / 25 mm, and no adhesive remained on the glass plate, and the reworkability was good.

  The pressure-sensitive adhesive (4) was applied to “Lumirror T-60-100” to 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. After one week, the release film was peeled off, and the adhesive surface was pressure bonded to the glass substrate with a load of 2 kg. Using this, a heat and humidity resistance test was carried out under conditions of 65 ° C. and 95% RH for 1000 hours. The test results are shown in Table 2.

  By blending 3-isocyanatopropyltriethoxysilane, the adhesive strength and the adhesive film appearance were not changed before and after the wet heat resistance test, which was excellent.

Example 5
The block copolymer (1) is diluted with ethyl acetate so that the heating residue is 50%, and 5 phr of “Tinuvin 900” (benzotriazole UV absorber of Ciba Specialty Chemicals Co., Ltd.) is blended. Stirring was carried out until evenly dissolved. Next, isophorone diisocyanate was blended and mixed well as a curing agent so that the NCO index = 1/1. After measuring the heating residue, ethyl acetate was added to adjust the heating residue to 40%. This was made into the adhesive (5).

  The pressure-sensitive adhesive (5) was applied to “Lumirror T-60-100” to 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 adhesive strength was as strong as 20 N / 25 mm. No adhesive remained on the glass plate, and the reworkability was good.

  The light transmittance of the adhesive film was measured using “UV-2550” (a spectrophotometer manufactured by Shimadzu Corporation). The UV transmittance at 380 nm was 1.6%, and the visible light transmittance at 550 nm was 92.0%, which was excellent in UV cut performance and visible light transparency.

Example 6
An acrylic resin (ratio-1) was produced in the same manner as in Example 1. That is, 214.3 g of butyl acetate as a polymerization solvent was charged into a 2-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”, and it was confirmed that the oxygen concentration was less than 0.2 vol%.

  While the bubbling of nitrogen gas was continued, 0.84 g of 4-benzoyloxy-2,2,6,6-tetramethylpiperidine (0.40% by weight of the acrylic monomer mixture (a-1)) was charged into the flask. And dissolved to be uniform. Next, 0.778 g of benzoyl peroxide (equal molar amount with 4-benzoyloxy-2,2,6,6-tetramethylpiperidine) was charged, and stirring was continued until the benzoyl peroxide dissolved and became a homogeneous solution. The temperature increase was started, the temperature was increased to 90 ° C. in 30 minutes, and the temperature was maintained at 90 ° C. below.

  Charge 500 g of acrylic monomer mixture (a-1) (n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate (= 90/5/5) into a container and use a constant flow pump. The solution was dropped into the flask in 2 hours, and then polymerization was continued until α was 1.0 (polymerization was continued until the polymerization rate was sufficiently increased) while maintaining 90 ° C. (required about 18 hours). The acrylic resin (ratio-1) was not a block copolymer, but was produced by living radical polymerization as in Example 1. (See FIG. 1) The produced acrylic resin (ratio-1) ), The heating residue was 70.2% and Mn was 115000.

  After blending the acrylic resin (ratio-1) / block copolymer (1) so that the heating residue ratio becomes 70/30, it is diluted with ethyl acetate so that the heating residue becomes 50%. -130 "was blended in 20 phr and stirred until evenly dissolved. Next, isophorone diisocyanate was blended and mixed well as a curing agent so that the NCO index = 1/1. After measuring the heating residue, ethyl acetate was added to adjust the heating residue to 40%. This was made into the adhesive (6).

Measurement of the rheology of the adhesive (6), the viscosity Pa shear rate 5.62S ^-1 is, 4.77Pas, viscosity Pb shear rate 562S ^-1 at 2.60 (Pa / Pb = 1.83) there were.

  The contact angle (23 ° C.) of the adhesive (6) with respect to the copper substrate was 78 °.

  The pressure-sensitive adhesive (6) was applied to a copper mesh with a bar coater 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. The total light transmittance of the copper mesh sheet coated with the pressure-sensitive adhesive (6) was 80.2%, and the haze was 3.5. The copper mesh sheet coated with the pressure-sensitive adhesive (6) had high transparency as a display film.

  The pressure-sensitive adhesive (6) had a sufficiently high contact angle with respect to the copper substrate. For this reason, it is guessed that it is excellent in the permeability to a copper mesh, and the surface smoothness of an adhesive. When the penetration state of the adhesive (6) into the copper mesh, the presence or absence of air bubbles, and the smoothness of the adhesive surface were observed with "Digital Microscope KH-3000VD", the adhesive (6) penetrated into every corner of the mesh. Air bubbles were not observed. Moreover, the pressure-sensitive adhesive surface was smooth, and the uneven profile of the copper mesh adhesive was completely restored. Since the pressure-sensitive adhesive (6) has an appropriate thixotropy and a high contact angle with copper, it was excellent in the permeability to the copper mesh and the surface smoothness of the pressure-sensitive adhesive.

Comparative Example 1
Radical polymerization of acrylic monomer mixture consisting of n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate (= 90/5/5) using toluene / ethyl acetate (30/70) as a solvent. An acrylic resin (ratio-2) having a Mn of 120,000 and a solid content of 70.2% was produced. Similarly, using toluene / ethyl acetate (30/70) as a solvent, n-butyl acrylate / 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate / styrene / glycidyl methacrylate (= 81.7 / 3/5 / The acrylic monomer mixture consisting of 0.3 / 10) was radically polymerized to produce an acrylic resin (ratio-3) having a Mn of 80,000 and a heating residue of 70.3%.

  A mixture of acrylic resin (ratio-2) / acrylic resin (ratio-3) (= 70/30) was diluted with ethyl acetate so that the heating residue was 50%, and 20 phr of “YS polystar TH-130” was blended. The mixture was stirred until it was uniformly dissolved. Next, isophorone diisocyanate was blended and mixed well as a curing agent so that the NCO index = 1/1. After measuring the heating residue, ethyl acetate was added to adjust the heating residue to 40%. This is designated as an adhesive (7).

  The pressure-sensitive adhesive (7) had no compatibility between the acrylic resin (ratio-2) and the acrylic resin (ratio-3), and became a cloudy, semi-gelled solution.

  Since the pressure-sensitive adhesive (7) was in a semi-gel state, rheological measurement could not be performed. Moreover, since it was opaque, the contact angle with respect to copper could not be measured.

  The pressure-sensitive adhesive (7) 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. The adhesive film was opaque, non-uniform with streaky irregularities.

  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 adhesive strength was 3 N / 25 mm or less, which was inappropriate as an adhesive.

  The pressure-sensitive adhesive (7) was applied to a copper mesh 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. The copper mesh sheet was opaque, and “Digital Microscope KH-3000VD” was used to observe the state of penetration of the adhesive (7) into the copper mesh, the presence or absence of bubbles, and the smoothness of the adhesive surface. 7) did not penetrate at all.

  The pressure-sensitive adhesive (7) obtained by simply blending polymers having the same composition was unsuitable as a pressure-sensitive adhesive for display.

Comparative Example 2
Acrylic resin (ratio-2) was diluted with ethyl acetate so that the heating residue was 50%, and 20 phr of “YS Polystar TH-130” was mixed and stirred until it was uniformly dissolved. Next, isophorone diisocyanate was blended as a curing agent so that the NCO index = 1/1 and mixed well. After measuring the heating residue, ethyl acetate was added to adjust the heating residue to 40%. This is designated as an adhesive (8).

Measurement of the rheology of the adhesive (8), the viscosity Pa shear rate 5.63S ^-1 is, 2.47Pas, viscosity Pb shear rate 563S ^-1 at 2.46 (Pa / Pb = 1.004) there were.

  The contact angle (23 ° C.) of the adhesive (8) with respect to the copper substrate was 30 °.

  The pressure-sensitive adhesive (8) 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 adhesive strength was 5 N / 25 mm, and the adhesive strength was weak.

  The pressure-sensitive adhesive (8) was applied to a copper mesh 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. The copper mesh sheet was opaque, and the penetration state of the adhesive (8) into the copper mesh, the presence of air bubbles, and the smoothness of the adhesive surface were observed by “Digital Microscope KH-3000VD”. (8) did not penetrate at all.

  The pressure-sensitive adhesive (8) using an acrylic resin (ratio-2) that is not an AB block copolymer was inappropriate for copper mesh. This is due to the fact that the rheology of the adhesive (8) is close to Newtonian (Pa / Pb = 1.004) and the contact angle with the copper substrate is low (30 °).

It is the relationship between the polymerization rate (α (%)) and the number average molecular weight (Mn). It is a measurement result of the polymerization rate ((alpha) (%)) and number average molecular weight (Mn) of Example 1. FIG. It is a rheological measurement result of an adhesive (1). It is a measurement result of the polymerization rate ((alpha) (%)) and number average molecular weight (Mn) of Example 3. It is a rheological measurement result of an adhesive (2). It is a measurement result of polymerization rate (alpha (%)) and number average molecular weight (Mn) of Example 4. It is a rheological measurement result of an adhesive (3).

Claims (8)

  The adhesive composition whose contact angle with respect to copper in 23 degreeC is 50 degrees-100 degrees, when a heating residue is 35 to 55 weight%. The pressure-sensitive adhesive composition according to claim ^1, wherein the pressure-sensitive adhesive is a thixotropic fluid at a shear rate of 10 ⁰ to 10 ³ s ^-1 when the heating residue is 35 to 55% by weight.     The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive contains an organoalkoxysilane compound having an isocyanate group and an alkoxysilane group in the molecule.   The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive contains zinc oxide having an average primary particle diameter of 100 nm or less.     The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive contains an acrylic resin for pressure-sensitive adhesive having a number average molecular weight of 3 to 500,000.   The acrylic resin for pressure-sensitive adhesives is an acrylic resin obtained by radical copolymerization of any one or more of a hydroxyl group-containing acrylic monomer, an epoxy group-containing acrylic monomer, and a carboxyl group-containing acrylic monomer. Adhesive composition.   The acrylic resin for pressure-sensitive adhesives was obtained by radical copolymerization of an acrylic copolymer segment (A) in which a hydroxyl group-containing acrylic monomer was radically copolymerized and an epoxy group-containing acrylic monomer or a carboxyl group-containing acrylic monomer. The pressure-sensitive adhesive composition according to any one of claims 1 to 6, which comprises an AB block copolymer comprising an acrylic copolymer segment (B).     Acrylic copolymer segment (A) obtained by radical copolymerization of a hydroxyl group-containing acrylic monomer, and an acrylic copolymer segment (B) obtained by radical copolymerization of an epoxy group-containing acrylic monomer or a carboxyl group-containing acrylic monomer 8. The pressure-sensitive adhesive composition according to claim 7, wherein the AB block copolymer is a radical copolymerized reaction product of a hindered amine compound and an organic peroxide as a polymerization initiator.

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