TWI627254B - Adhesive tape - Google Patents

Abstract

An object of the present invention is to provide an adhesive tape for fixing an optical film which is susceptible to distortion, and to use a water-based adhesive having reduced VOC, it is also possible to suitably fix a member and to suppress distortion of the optical film.

The solution of the present invention is an adhesive tape for fixing to an optical film, wherein the adhesive layer connected to the optical film is an adhesive layer composed of a water-dispersed acrylic adhesive composition, and an adhesive layer The glass transition temperature is below -5 ° C, and the gel fraction is 25 to 45%. The adhesive tape can be well fixed between the parts, has good anti-repulsion property, and can appropriately suppress the distortion of the optical film.

Description

Adhesive tape

The present invention relates to an adhesive tape for fixing an optical film used in an image display device such as a liquid crystal display or an organic EL (Electro Luminescence) display.

An image display device such as a liquid crystal display is used in a wide range of fields including a word processor or a personal computer, and can be used in an electronic notebook, a mobile phone, a PHS, a smart phone, a game machine, an electronic book, etc. A display device for electronic devices that has become smaller and smaller. In the image display module such as the LCD module of the image display device, a display panel in which a backlight module is fixed by an adhesive tape and an LCD panel provided on the surface is widely used, and is displayed on the backlight module. The surface of the panel is fixed, and an optical film such as a cymbal is often provided.

For example, in a liquid crystal display of a sidelight type backlight type, a laminated film, a light guide plate, a diffusion sheet, and the like are generally provided, and an optical film such as a cymbal sheet is provided on the surface layer, and a lamp reflector is disposed on the side of the light guide plate, and LEDs are stacked in layers. (Light Emitting Diode), a backlight module of a light source such as a cold cathode tube, and an LCD panel. Moreover, between the LCD panel and the backlight module, a double-sided adhesive tape is sandwiched (usually punched into a frame-like shape, and the width thereof is usually about 0.5 mm to about 10 mm). The double-sided adhesive tape has a case in which only the surface of the backlight module is in contact with the film, or a case where the film on the surface of the backlight module is bridged with the case in which the backlight module is housed, and The task of fixing the diffusion sheet or the like provided on the lower side, or preventing the intrusion of dust or cushioning property, prevents the rupture of the above-mentioned parts due to the punching.

Further, in the above adhesive tape, it is strongly required to block leakage light from a light source or to provide light blocking property and light reflectivity in order to utilize light efficiently. Such an adhesive tape is used to review the improvement of the conventional characteristics, and to disclose an adhesive tape for an LCD module which is thin and has both light-shielding properties and light reflectivity (see Patent Document 1).

However, in recent years, in the adhesive tape used in this part, in view of the high performance of the electronic device to be used, and in particular, the thinning or multi-functioning of the mobile phone, problems that have not been regarded as problems in the past have emerged. One of the problems is that, as the multi-functional mobile phone is thinned, the thickness of the internal member is reduced. However, due to the thinning of the optical film, the optical film attached to the periphery by the double-sided adhesive tape is placed at a high temperature in the reliability test. When it is down, the problem of distortion of the optical film occurs. If the light is illuminated by the light that is so distorted, the image in the LCD panel becomes a lack of sharpness. Such a problem occurs particularly prominently with the large screen of a portable electronic terminal such as a smart phone or a tablet terminal. In view of this, there is an adhesive tape which is proposed to suppress distortion of an optical film, and it is attempted to fix the components to each other while suppressing distortion of the optical film (see Patent Documents 2 to 3).

On the other hand, in view of environmental concerns, in recent years, in the peripheral materials of such image display devices, it has been desired to reduce the VOC (volatile organic compound) material, and in the field of electronic devices, Since this requirement is particularly high, conversion from the solvent-based adhesive to the aqueous adhesive is expected even in the adhesive layer of the adhesive tape. Therefore, it is desirable to achieve an adhesive tape using a water-based adhesive which can securely fix the parts to each other and can suitably suppress the distortion of the optical film. Again, with the end of carrying electrons In order to suppress the peeling of the adhesive tape due to the distortion of the terminal, etc., it is also desired to improve the good fixation of the component, particularly the anti-repellency.

Prior technical literature Patent literature

Patent Document 1 Japanese Patent Laid-Open No. 2004-156015

Patent Document 2 Japanese Special Open 2008-248226

Patent Document 3 Japanese Special Open 2010-168437

An object of the present invention is to provide an adhesive tape for fixing an optical film which is susceptible to distortion, and to use a water-based adhesive having reduced VOC, it is also possible to suitably fix a member and to suppress distortion of the optical film.

In the present invention, an adhesive tape is used for a fixed adhesive tape of an optical film, wherein the adhesive layer which is in contact with the optical film is an adhesive layer composed of a water-dispersed acrylic adhesive composition. The glass transition temperature of the adhesive layer is below -5 ° C, and the gel fraction is 25 to 45%. The adhesive tape can solve the above problem.

In the adhesive tape of the present invention, although the VOC-based water-based adhesive layer is used, the adhesive layer applied to the side of the optical film has a glass transition temperature of -5 ° C or less and a gel fraction of 25 °. 45% adhesive layer for good fixing between parts, with good resistance to platooning Repulsive, and the distortion of the optical film can be suitably suppressed. Therefore, it has excellent environmental adaptability, and at the same time, when an optical film is used as an object to be adhered, it is also possible to suppress a decrease in visibility due to distortion of the optical film, or adhesion due to deformation of a casing or the like. Since the strip is peeled off, it is suitable for fixing between parts of an image display device using an optical film as an object to be adhered, in particular, fixing of an optical film and a transparent panel.

[Formation of the Invention]

The adhesive tape of the present invention is used for a fixed adhesive tape of an optical film, and the adhesive layer which is in contact with the optical film is an adhesive layer composed of a water-dispersed acrylic adhesive composition, and a glass transition temperature of the adhesive layer Below -5 ° C, the gel fraction is 25 to 45%.

[Adhesive layer]

In the adhesive tape of the present invention, the adhesive layer attached to the optical film is an adhesive layer formed of a water-dispersible acrylic adhesive composition in which acrylic polymer emulsion particles are dispersed in an aqueous medium. In the present invention, the glass transition temperature (Tg) of the adhesive layer is -5 ° C or lower, preferably -10 ° C or lower, more preferably -15 ° C or lower, and the flexibility of the adhesive is sufficiently ensured. Thereby, even when the optical film is distorted, the distortion can be appropriately suppressed while suppressing the distortion. By adhering the adherend sufficiently with the adhesive, it is ensured that the adherend is adhered to the adhesive to achieve appropriate repellency.

The glass transition temperature of the adhesive layer constituting the adhesive tape of the present invention is the peak temperature of the loss tangent (tan δ) of the dynamic viscoelastic spectrum. Determination of dynamic viscoelasticity, for example using a viscoelastic testing machine (Rheometrics System, product name: Ares 2KFRTN1), the test piece is sandwiched between the parallel discs of the measuring part of the test machine, and the storage from -50 ° C to 150 ° C is measured at a frequency of 1 Hz and a temperature increase rate of 2 ° C / min. The elastic modulus (G') and the loss elastic modulus (G"). The tan δ is calculated by the following calculation formula.

Tan δ=G”/G’

The test piece may also be sandwiched between the parallel discs by an adhesive having a thickness of 0.5 to 2.5 mm, or may be sandwiched between the parallel discs by overlapping layers of the substrate and the adhesive. Furthermore, the latter case does not affect the loss of the tangential peak temperature of the dynamic viscoelastic spectrum of the adhesive even if the substrate is sandwiched.

The adhesive layer of the adhesive tape of the present invention is an adhesive layer having a gel fraction of 25 to 45%. By the above glass transition temperature and the gel fraction of the adhesive layer being in this range, it is ensured that the adherend exhibits sufficient wettability and adhesion flexibility, and on the other hand, by ensuring resistance to stress The cohesive force can well suppress the distortion of the optical film, and can achieve a suitable anti-repellency. Further, the gel fraction was obtained by immersing the adhesive layer in toluene for 24 hours, and measuring the insoluble component and the gel fraction expressed by the mass ratio before and after the immersion.

The adhesive tape of the present invention has the above-mentioned glass transition temperature and the gel fraction of the adhesive layer, but the glass transition temperature of the adhesive layer is the glass transition temperature of the acrylic copolymer used in the adhesive composition or The glass transition temperature, softening point, blending amount, etc. of the tackifying resin are appropriately adjusted. Further, the gel fraction is a functional group monomer or a functional group which can be introduced in an acrylic copolymer which reacts with a crosslinking agent by the amount of a crosslinking agent or a crosslinking agent added to the adhesive composition. The volume is suitable for adjustment.

(acrylic copolymer)

As the water-dispersible acrylic pressure-sensitive adhesive composition used in the pressure-sensitive adhesive layer, a composition of emulsion particles in which an acrylic copolymer is dispersed in an aqueous medium can be used. The acrylic copolymer preferably has a glass transition temperature of -45 ° C to -25 ° C as measured by dynamic viscoelasticity, and more preferably -40 ° C to -30 ° C. By setting the glass transition temperature of the acrylic copolymer to this range, it is easy to sufficiently ensure the flexibility of the adhesive. Thereby, even when the optical film is distorted, it is easy to suppress the distortion while appropriately following the distortion. Further, by sufficiently adhering the adherend to the adherend, it is easy to ensure adhesion between the adherend and the adhesive, and it is easy to achieve appropriate anti-repellency.

The glass transition temperature of the acrylic copolymer constituting the adhesive layer of the adhesive tape of the present invention is the peak temperature of the loss tangent (tan δ) of the dynamic viscoelastic spectrum. In the measurement of dynamic viscoelasticity, a sheet composed only of an acrylic copolymer was prepared, and it was measured similarly to the above-mentioned adhesive layer.

As the (meth) acrylate monomer used in the acrylic copolymer, a (meth) acrylate monomer used in an adhesive can be suitably used, and among them, an alkyl group having a carbon number of 4 to 8 can be preferably used. The (meth) acrylate monomer serves as a main monomer component. As the (meth) acrylate monomer having 4 to 8 carbon atoms, for example, n-butyl (meth) acrylate, isobutyl (meth) acrylate, or t-butyl (meth) acrylate can be used. (meth) acrylate such as 2-ethylhexyl acrylate, isooctyl (meth) acrylate or n-octyl (meth) acrylate. Among them, n-butyl acrylate and/or 2-ethylhexyl acrylate may be preferably used, and particularly preferably 2-ethylhexyl acrylate, since the glass transition temperature of the obtained adhesive layer is easily controlled. Lower glass transition temperature. Moreover, the compatibility with the tackifier resin is easily improved, and the improvement of the adhesion between the substrate and the adherend is also easily obtained.

The content of the (meth) acrylate having an alkyl group having 4 to 8 carbon atoms is preferably from 50 to 98% by mass, particularly preferably from 80 to 98% by mass, based on the monomer component used in the acrylic copolymer. By setting the content of the (meth) acrylate having an alkyl group having 4 to 8 carbon atoms in this range, it is easy to sufficiently ensure the flexibility of the adhesive. Thereby, even when the optical film is distorted, it is easy to suppress the distortion while appropriately following the distortion. Further, by sufficiently adhering the adherend to the adherend, it is easy to ensure adhesion between the adherend and the adhesive, and it is easy to achieve appropriate anti-repellency.

Further, in particular, when 2-ethylhexyl acrylate which can be preferably used is used, it is preferably 40% by mass or more, and particularly preferably 60% by mass or more based on the monomer component used in the acrylic copolymer. More preferably, it accounts for 80% by mass or more, and more preferably 90% by mass or more. By being in this range, it is easy to sufficiently ensure the flexibility of the adhesive. Thereby, even when the optical film is distorted, it is possible to easily suppress the distortion while appropriately following the distortion.

In the present invention, as the (meth) acrylate monomer forming the acrylic copolymer, a (meth) acrylate monomer other than the above may be used in combination. The (meth) acrylate monomer other than the above may, for example, be a (meth) acrylate monomer such as methyl (meth) acrylate or ethyl (meth) acrylate, and one of these may be used in combination. 2 or more types. Among them, a (meth) acrylate having an alkyl group having 2 or less carbon atoms such as methyl (meth)acrylate or ethyl (meth)acrylate is preferably used in combination, and the amount thereof is preferably from 1 to 10% by mass.

In the present invention, in order to increase the cohesive force in the acrylic copolymer emulsion particles or between the particles, it is preferred to use a carboxyl group-containing monomer. As the carboxyl group-containing monomer, a carboxyl group-containing vinyl monomer selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, phthalic acid, phthalic anhydride, and crotonic acid can be used. One or two or more. Among them, acrylic acid and methacrylic acid are easy to ensure cohesive force by interaction of carboxyl groups, and there are many cross-linking agents to be reacted, and there are many means for improving cohesive force, and they have a mutual appearance with a nitrogen-containing vinyl monomer which will be described later. The advantages of functions and the like are preferred.

The content of the carboxyl group-containing monomer is preferably from 0.5 to 10% by mass, particularly preferably from 0.5 to 5% by mass, more preferably from 1.5 to 3.5% by mass, based on the monomer component forming the acrylic copolymer. By being within this range, the crosslinking reaction with the crosslinking agent proceeds easily and satisfactorily. Further, it is easy to ensure the cohesive force against the stress, the distortion of the optical film can be satisfactorily suppressed, and the appropriate repellency can be easily achieved.

In the present invention, as the monomer component of the acrylic copolymer, it is preferred to further use a nitrogen-containing vinyl monomer. It is presumed that the nitrogen-containing vinyl monomer has an effect of pulling a carboxyl group which is easily aligned on the surface of the particle into the particle by interaction with an acid group in the emulsion particle of the acrylic copolymer, particularly a carboxyl group. The content of the nitrogen-containing vinyl monomer is from 0.1 to 4.5% by mass, preferably from 0.5 to 4% by mass, more preferably from 0.5 to 3.5% by mass.

As the nitrogen-containing vinyl monomer, a nitrogen-containing monomer having a mercaptoamine group can be preferably used. Compared with the amine-based nitrogen-containing monomer group, the nitrogen-containing single system having a mercaptoamine group is not excessively strong in interaction with the acid group, and can be suitably maintained. The cohesive force in the emulsion particles interacts with the particles, and since it is easy to obtain cohesive force as an adhesive, it is easy to obtain suitable adhesion and rework. As the nitrogen-containing monomer having a guanamine group, for example, N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylonitrile, acrylamide, N,N- can be used. One or two or more selected from the group consisting of dimethyl acrylamide.

The ratio of the nitrogen-containing vinyl monomer to the vinyl monomer having a carboxyl group in the acrylic copolymer is not particularly limited, but constitutes a nitrogen-containing vinyl monomer in the monomer component of the acrylic copolymer. The molar number is regarded as X, and when the molar number of the vinyl monomer having a carboxyl group is regarded as Y, the molar ratio X/Y is preferably from 1/1 to 1/20, particularly preferably 1/1 to 1 /5, more preferably 1/1~1/3. When it is in this range, the reaction of the vinyl monomer which has a carboxyl group, and the crosslinking agent mentioned later is easy to carry out.

In the acrylic copolymer to be used in the invention, a monomer other than the above may be used as needed. As an example of such a monomer, (meth)acrylic acid-2- can be suitably used in the hydroxyl group-containing monomer. An alcoholic hydroxyl group-containing monomer such as hydroxyethyl ester, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate. Examples of the ketone group-containing or aldehyde group-containing monomer include diacetone acrylamide, diacetone methacrylamide, acrolein, decyl styrene, vinyl methyl ketone, and vinyl ethyl ketone. Vinyl isobutyl ketone, diacetone acrylate, diacetone methacrylate, acetonitrile acrylate, 2-hydroxypropyl acrylate acetamidine acetate, butane diol acrylate acetate, and the like. Examples of the decane-based monomer include 3-methylpropenyloxypropylmethyldimethoxydecane [for example, KBM-502 manufactured by Shin-Etsu Chemical Co., Ltd.], 3-methylpropenyloxypropyl group. Three Oxydecane [for example, KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.], 3-methacryloxypropylmethyldiethoxydecane [for example, KBE-502 manufactured by Shin-Etsu Chemical Co., Ltd.], 3-methyl Acryloxypropyltriethoxysilane (for example, KBE-503 manufactured by Shin-Etsu Chemical Co., Ltd.), 3-acryloxypropyltrimethoxydecane (for example, EBM-5103 manufactured by Shin-Etsu Chemical Co., Ltd.), and the like. Further, examples of the hydroxymethyl group-containing monomer include N-methylol acrylamide. Further, examples of the phosphoric acid group-containing monomer include Sipomer PAM-100, PAM-200, PAM-300, etc., which are manufactured by RODIA Nikko Co., Ltd., and may account for 20% of the monomer components forming the acrylic copolymer. The ratio of the mass% or less is used, and one type or two or more types can be used.

The acrylic copolymer used in the present invention preferably has a weight average molecular weight of from 50 to 1.2 million, preferably from 60 to 1,000,000. By being in this range, the flexibility to exhibit wettability and adhesion to the adherend can be improved, and on the other hand, the cohesive force of the resistant stress can be increased, and the distortion of the optical film can be satisfactorily suppressed, and it is easy. Achieve proper resistance to repellency. The aforementioned weight average molecular weight is converted to standard polystyrene by gel permeation chromatography (GPC). As a measurement condition, TSKgel GMHXL [manufactured by Tosoh Corporation] was used for the column, the column temperature was 40 ° C, the eluent was tetrahydrofuran, the flow rate was 1.0 mL/min, and the standard polystyrene was TSK standard polystyrene.

In order to adjust the molecular weight, a chain transfer agent can also be used in the polymerization. As the chain transfer agent, a well-known chain transfer agent such as lauryl mercaptan, propylene propyl thiol, thioglycolic acid, 2-mercaptoethanol, thioglycolic acid, thioglycol-2-ethylhexyl ester, 2, 3 can be used. - dimethylmercapto-1-propanol.

(tackifying resin)

In the water-dispersible acrylic pressure-sensitive adhesive composition used in the present invention, in order to exhibit sufficient wettability and adhesion to the adherend and to improve the cohesive force against the stress, it is preferred to use a tackifier resin. The glass transition temperature of the tackifying resin is preferably from 30 to 120 ° C, particularly preferably from 40 to 100 ° C, more preferably from 45 to 80 ° C, and even more preferably from 50 to 60 ° C. The adhesion is improved by blending a tackifying resin having a glass transition temperature higher than that of the acrylic copolymer.

The glass transition temperature of the tackifying resin used in the adhesive of the adhesive tape of the present invention is in the stepwise change of the glass transition of the DSC curve measured by the DSC measuring apparatus, and JIS K7121 specifies the glass transition as the intermediate point. Temperature temperature. As a specific measurement method, for example, a DSC curve measured by a DSC measuring device (manufactured by Mettler-Toledo Co., Ltd., trade name: DSC822) is used to analyze the value using a software attached to the device. The sample was dried at 60 ° C for 2 days or more under vacuum using a vacuum dryer. The measurement was continued twice at a temperature increase rate of 2 ° C/min in the range of -50 ° C to 200 ° C, and the second measurement data was analyzed to calculate the glass transition temperature.

As the tackifier resin used in the present invention, an emulsion type tackifier resin is preferably used from the viewpoint of using a water-dispersible adhesive composition. Examples of the emulsion-type tackifying resin include rosin-based, polymerized rosin-based, polymerized rosin-ester-based, rosin-phenol-based, stabilized rosin-ester-based, disproportionated rosin-ester, decene-based, indophenol-based, and petroleum-based resins. .

Among them, a polymerized rosin ester-based tackifying resin and/or a rosin-based tackifying resin is preferably used. Specifically, the polymerized rosin ester-based tackifying resin is, for example, Super Ester E-650 [Arakawa Chemical Industry Co., Ltd.], Super Ester E-788 [Arakawa Chemical Industry Co., Ltd.], Super Ester E-786-60 [Arakawa Chemical Industry Co., Ltd.], Super Ester E -865 [Arakawa Chemical Industry Co., Ltd.], Super Ester E-865NT [Arakawa Chemical Industry Co., Ltd.], Harister SK-508 [HARIMA Chemical Co., Ltd.], Harister SK-508H [HARIMA Chemical Co., Ltd. , Harister SK-816E [HARIMA Chemicals Co., Ltd.], Harister SK-822E [HARIMA Chemicals Co., Ltd.], Harister SE-323NS [HARIMA Chemicals Co., Ltd.], etc., rosin ester-based tackifying resins, for example It is Super Ester NS-125A [Arakawa Chemical Industry Co., Ltd.], Super Ester NS-100H [Arakawa Chemical Industry Co., Ltd.], Harister SK-90D-55 [HARIMA Chemical Co., Ltd.], and Harister SK-385NS [HARIMA Chemicals Co., Ltd.], etc., modified rosin ester-based tackifying resins are, for example, Harister SK-501NS [HARIMA Chemicals Co., Ltd.], Harister SK-370N [HARIMA Chemicals Co., Ltd.], etc. The adhesive resin is, for example, Super Ester NS-120B [Arakawa Chemical Industry Co., Ltd.], Super Ester NS-100A [Arakawa Chemical Industry Co., Ltd.], and the rosin phenol-based tackifying resin such as Tamanol E-100 [Arakawa Chemical Co., Ltd.] Industrial (stock) system], Tamanol E-200 [Arakawa Chemical Industry Co., Ltd.], Tamanol E-200NT [Arakawa Chemical Industry Co., Ltd.].

The blend ratio of the acrylic copolymer/tackifying resin is, in terms of parts by mass, the acrylic copolymer/tackifying resin=100/10~100/40 is suitable, and more preferably the acrylic copolymer/tackifying resin= 100/15~100/35. When it is in this range, the sufficient wettability to the adherend, the display of the adhesiveness, and the cohesive force of the resistant stress can be improved in a well-balanced manner.

(crosslinking agent)

In the water-dispersible acrylic pressure-sensitive adhesive composition used in the present invention, a crosslinking agent is preferably used for the purpose of improving the cohesive force of the obtained pressure-sensitive adhesive layer. As the crosslinking agent, a known isocyanate crosslinking agent, epoxy crosslinking agent, aziridine crosslinking agent, polyvalent metal salt crosslinking agent, metal chelate crosslinking agent, and ketone can be used. Lanthanide crosslinking agent, An oxazoline crosslinking agent, a carbodiimide crosslinking agent, a decane crosslinking agent, a glycidyl (alkoxy) epoxy decane crosslinking agent, and the like. Among them, a crosslinking agent of a type which is added after the completion of the polymerization to cause a crosslinking reaction is preferred. For example, an isocyanate type crosslinking agent and an epoxy type crosslinking agent are mentioned. An oxazoline crosslinking agent, a carbodiimide crosslinking agent, a glycidyl (alkoxy) epoxy decane crosslinking agent, and the like. Specifically, among the isocyanate-based crosslinking agents, Burnock DNW-5000 [manufactured by DIC Co., Ltd.], Burnock DNW-5010 [manufactured by DIC Co., Ltd.], Burnock DNW-5100 [manufactured by DIC Co., Ltd.], Burnock DNW-5500 [DIC (share) system], Aquanate 100 [Japanese polyurethane industry (stock) system], Aquanate 105 [Japanese polyurethane industry (stock) system], Aquanate 110 [Japanese polyamine Formate system (stock system)], Aquanate 120 [made by Japan Polyurethane Industry Co., Ltd.], Aquanate 130 [made by Japan Polyurethane Industry Co., Ltd.], Aquanate 200 [Japanese Polyurethane Ester industry (stock) system], Aquanate 210 [made by Japan Polyurethane Industry Co., Ltd.], LS2319 [Sumi-made BAYER urethane (manufactured by the company)], LS2336 [Liuyi BAYER urethane) (manufactured by the company), Bayhydur 3100 [manufactured by BAYER urethane (manufactured by the company)], etc., among the epoxy-based crosslinking agents, Denacol EX-832 [NAGASE Chemical Industry Co., Ltd.], Denacol EX-841 [NAGASE Chemical Industry Co., Ltd.], Tetrad C [Mitsubishi Gas Chemical Co., Ltd.], Tetrad X [Mitsubishi Gas Chemical Co., Ltd.], etc. Examples of the oxazoline crosslinking agent include Epocros WS-500 [manufactured by Nippon Shokubai Co., Ltd.], Epocros WS-700 [(Japan) Catalyst], and Epocros K-2010E [(Japan) Catalyst] System], Epocros K-2020E [(share) Nippon Catalyst], Epocros K-2030E [(share) Nippon Catalyst], Carbodilite SV-02 in carbodiimide crosslinker Nisshin Textile Co., Ltd., Carbodilite V-02 [Nissin Textiles Co., Ltd.], Carbodilite V-02-L2 [Nissin Textiles Co., Ltd.], Carbodilite V-04 [Nissin Textiles Co., Ltd.], Carbodilite E-01 [ Nisshin Textile Co., Ltd., Carbodilite E-02 [Nisshin Textile Co., Ltd.], Carbodilite E-03A [Nisshin Textile Co., Ltd.], Carbodilite E-04 [Nisshin Textile Co., Ltd.], in epoxy propyl (alkane) Examples of the oxy) epoxy decane-based crosslinking agent include 2-(3,4-epoxycyclohexylethyltrimethoxydecane [KBM-303; manufactured by Shin-Etsu Chemical Co., Ltd.], γ- Glycidoxypropyltrimethoxydecane [KBM-403; Shin-Etsu Chemical Co., Ltd.], γ-glycidoxypropylmethyldiethoxydecane [KBE-402; Shin-Etsu Oxygen (manufactured by oxygen), γ-glycidoxypropyltriethoxydecane [KBE-403; Shin-Etsu Chemical Co., Ltd.] and the like.

Among them, a crosslinking agent which reacts with a vinyl monomer having an acid group is preferably used, and the above-mentioned isocyanate crosslinking agent, epoxy compound, or preferably An oxazoline compound, a carbodiimide crosslinking agent, a glycidyl (alkoxy) epoxy decane compound, or the like. The increase in cohesive force can be suitably exhibited by using a crosslinking agent which reacts with such acid groups.

(additive)

In the water-dispersed acrylic pressure-sensitive adhesive composition used in the present invention, as an additive, it does not hinder the desired effect of the present invention as needed. In the range of pH, alkali (ammonium water, etc.) for adjusting pH or acid, plasticizer, softener, antioxidant, fiber made of glass or plastic, fillers such as balloons, beads, metal powder, pigments, dyes, etc. A well-known person such as a coloring agent, a pH adjusting agent, a film forming aid, a leveling agent, a tackifier, a water repellent, and an antifoaming agent is arbitrarily added to the adhesive composition.

The thickness of the adhesive layer is preferably from 5 to 50 μm, more preferably from 10 to 30 μm. When the thickness is 5 μm or more, sufficient adhesion can be obtained, and if it is 50 μm or less, it can be applied to a display device which is thinner and lighter.

[Support]

The support system used in the present invention is not particularly limited, and various supports used for fixing the peripheral members of the image display device can be used. The support may be, for example, a support composed of a resin film or a support having a colored layer on the resin film. When the optical film is fixed to other members, especially when the optical film and the transparent panel are fixed, since the light shielding property or the light reflection property is required, it is preferably used on the resin film when achieving good light blocking performance or light reflection performance. A support having a colored layer is provided.

As the resin film used for the support, a conventionally known resin film can be used, and examples thereof include cellophane, polyethylene, polypropylene, nylon, polystyrene, polyimine, and polyester. Among them, polyester is preferably used because it is excellent in strength or insulation. Further, polyethylene terephthalate is preferably used because it has good adhesion to an ink layer using a polyurethane resin.

The thickness of the resin film to be a support is preferably 6 to 100 μm. When the thickness is 6 μm or more, the film is likely to be broken at the time of peeling, and when it is 100 μm or less, peeling is likely to occur at the time of attaching to the adherend. More preferably 12 to 50 μm.

Further, the resin film itself may be colored white or black, and if the resin film is a light-reflective white resin film, it is preferably used for the image display portion of the image display device because the brightness of the image display can be improved. . Among them, white polyethylene terephthalate having insulating properties and light diffusing reflectivity is preferred. Further, when the resin film is a black resin film having a light-shielding property, it is preferable to improve the contrast of the image display device. Among them, black polyethylene terephthalate is preferred because it can impart excellent light blocking properties.

When a colored layer is provided on such a resin film, it is preferred to use a colored ink. In the colored ink using the colored layer, a colored ink used for a color ribbon such as a light-shielding tape or a light reflection tape used for fixing the peripheral member of the image display device can be suitably used. In particular, the halogen content of the colored layer is 0.3% by mass or less, preferably 0.05% by mass or less, and particularly preferably a halogen is not substantially contained. Such a coloring layer which reduces the halogen content is used as a coloring ink which does not use a halogen or sulfur-containing resin such as a vinyl chloride resin as a binder resin, particularly because it is difficult to obtain adhesion of the adhesive layer, if the adhesive layer is When the adhesiveness is high, it is difficult to obtain reworkability, but the above-mentioned adhesive layer used in the present invention can achieve appropriate adhesion and reworkability even in the case of the colored layer having a low halogen content. Here, the halogen content is the amount of detection in the case of fluorescent X-ray analysis. For example, examples of the analyzer for fluorescent X-rays include "ZSX Primus" and "ZSX Primus II" manufactured by Rigaku Corporation.

As the colored ink having a reduced halogen content, a halogen-containing or sulfur-containing resin such as a vinyl chloride-based resin is preferably used as the coloring ink of the binder resin. As such a binder resin, for example, a polyurethane resin, a polyester resin, a polyamide resin, an acrylic resin, a nitrocellulose, or the like can be used. Among them, from the viewpoint of adhesion to the adhesive layer and adhesion to the resin film of the laminated colored layer, a polyurethane resin is preferably used, and a polyester urethane resin is particularly preferably used.

When a polyester urethane resin is used as the binder resin, the glass transition temperature of the polyester urethane resin is preferably from -30 ° C to 30 ° C, particularly preferably from -20 ° C to 30 ° C, more preferably It is -15 ° C ~ 25 ° C, especially good -10 ° C ~ 25 ° C. When the peak temperature of tan δ of the polyester urethane resin is in this range, since the colored layer has suitable flexibility and hardness, it is particularly difficult to cause breakage due to cracking of the colored layer during redoing, and Peeling due to the flow of ink at high temperatures is less likely to occur.

Further, the glass transition temperature of the polyester urethane resin was determined by the peak temperature of tan δ of the dynamic viscoelastic spectrum at a frequency of 1 Hz measured as follows.

The polyester urethane resin was formed into a film by a bar coater at a thickness of 50 μm. Next, using a viscoelasticity tester, a test piece (sample length 20 mm, film thickness 50 μ) cut into a sample length of 20 mm was measured at a frequency of 1 Hz and a temperature rise time of 3 ° C / 1 minute, and measured from -150 ° C to 250 ° C. The storage elastic modulus (G') and the loss elastic modulus (G") until now. The loss tangent tan δ is calculated by the following calculation formula.

Loss tangent tan δ=G”/G’

Examples of the viscoelasticity testing machine include DMS210, DMS220, and DMS6100 manufactured by Seiko Instruments.

The colored ink used for the colored layer contains a curing agent used in a usual ink. However, as the curing agent, an aliphatic or alicyclic isocyanate-based curing agent is preferably contained. By crosslinking the polyester urethane having a glass transition temperature of -30 ° C to 30 ° C and the aliphatic or alicyclic isocyanate forming a relatively soft crosslinked structure, it is easy to control the elastic modulus and easily suppress Peeling of the ink interface and the adhesive interface due to the flow of the high temperature ink. Since it is easy to become a more suitable elastic modulus, it is difficult to cause cracks in the ink layer at the time of redoing, and it is easy to obtain an effect that the breakage of the adhesive tape is less likely to occur.

As the aliphatic or alicyclic isocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, trimethylhexamethylene isocyanate, 1,6,11-undecane three are used. Isocyanate, quaternary acid diisocyanate, isocyanate triisocyanate, 1,8-diisocyanate-4-isocyanate methyl octane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate. Further, it is preferred to use a trimer of such isocyanates, of which an adduct of a diisocyanate or a biuret or a urate body is preferred. Among them, an adduct or biuret or urethane system of hexamethylene diisocyanate or isophorone diisocyanate is easy to control the elastic modulus, preferably a biuret or a urate body. . The hardener may be added alone or in combination of two or more.

As the coloring agent for coloring the colored ink, a conventionally known pigment or dye containing no halogen can be used, and from the viewpoint of weather resistance, heat resistance, and dispersibility in the ink resin, it is preferably black in the case of black. ,white It is titanium oxide, calcium carbonate, barium sulfate, yellow iron oxide in yellow, iron oxide red in red, cyanine blue in blue, aluminum powder in silver, and mica titanium powder in pearl color. When the colored layer is used as the light shielding layer, it is preferred to form a black ink layer, and carbon black is preferred because it has excellent light blocking properties. Further, when the colored layer is used as the light-reflecting layer, it is preferred to form a white ink layer, and titanium oxide is preferably used.

The amount of the colorant to be added may be appropriately adjusted depending on the use, etc., and is preferably from 10 to 70%, more preferably from 40 to 50%, based on the solid content of the ink containing the colorant. When it is 10% or more, the light-shielding property is suitably exhibited, and when it is 70% or less, the dispersion becomes favorable.

The thickness of the colored layer can be suitably adjusted according to the desired characteristics. For example, when the colored layer is used as the light-shielding layer, it is preferably from 1 to 10 μm, more preferably from 3 to 7 μm, from the viewpoint of the light-shielding property and the workability at the time of punching the adhesive tape. Further, the thicker the thickness of the ink, the lower the elastic modulus is preferably from the viewpoint of reworkability.

Further, the colored layer may be a single layer, and two or more layers may be laminated in accordance with desired concealability, light reflectivity, and light blocking property. In particular, when the colored layer is used as the light-shielding layer, it is preferable to provide two or more coloring layers in order to prevent light leakage due to pinholes in order to increase the light-shielding property.

In the case where the color ribbon of the present invention is used as a light-shielding tape or a light-shielding reflection tape, the light-transmitting amount when the support is irradiated with light of 10000 cd/m ² is preferably 1 cd/m ² or less, more preferably 0.1 cd/m ^{2 .} the following.

[adhesive tape]

The adhesive tape of the present invention is an adhesive tape for fixing an optical film, wherein the above-mentioned adhesive attached to the optical film is provided on at least one side of the support. Adhesive tape on the layer. According to this configuration, it is possible to appropriately fix the optical film which is easily distorted while having excellent environmental compatibility due to the reduction in VOC, and it is excellent in repellency resistance and can appropriately suppress distortion of the optical film.

The adhesive tape may be a single-sided adhesive tape provided with an adhesive layer on one side of the support, or a double-sided adhesive tape provided with an adhesive layer on both sides of the support, but the fixed optical film is fixed. When fixed between parts of other members, a double-sided adhesive tape is preferred. The adhesive layer attached to the above optical film has a suitable adhesiveness for a transparent panel of various adherends, particularly a glass panel, and the like, and when it is a double-sided adhesive tape, it is preferably the same on both sides. Adhesive layer. Further, each of the adhesive layers may be a single layer of an adhesive layer, or a plurality of adhesive layers may be laminated, or a plurality of adhesive tapes may be laminated. Further, when a single-sided adhesive tape is used for fixing between the parts, it is also possible to apply the fixing between the parts by additionally providing a double-sided adhesive tape on the surface without the adhesive layer or by applying an adhesive.

The adhesive layer can be formed on the resin film or the light shielding layer by a method generally used in the application of an adhesive tape. Specifically, for example, the composition in which the pressure-sensitive adhesive layer is formed can be directly applied onto a support to be dried, or once applied to a separator, dried, and then bonded to a support to form a method. .

The thickness of the adhesive tape of the present invention is preferably from 20 to 100 μm, more preferably from 30 to 75 μm. Among them, the best is 40~65μm. If the thickness is within this range, it can be used as a component for fixing an image display device, particularly for a video display device of a small electronic device.

The adhesive tape of the present invention has a 180 degree peeling adhesion to the optical film and glass, preferably 7 to 15 N/20 mm, more preferably 8 to 13 N/20 mm. If the adhesion is within this range, the parts can be suitably fixed when the parts of the image display device are fixed.

The content of the halogen (chlorine bromo ‧ fluoro ‧ iodine) in the adhesive tape of the present invention is preferably 0.3% by mass or less, more preferably 0.05% by mass or less, and particularly preferably substantially no halogen. The halogen-removed adhesive tape is suitable for suppressing the malfunction of the image display device.

In the embodiment of the adhesive tape of the present invention, as the adhesive layer to be attached to at least the optical film, the adhesive layer may be provided on the support, and particularly preferably used in the support layer having a colored layer. The coloring layer of the body has a structure of an adhesive layer attached to the optical film. As a suitable specific example, both sides of the support having a colored layer on one surface of the resin film may be exemplified as an adhesive layer, and both sides of the support having a colored layer on both surfaces of the resin film may have an adhesive layer form. Wait. In these forms, if the colored layer is a light-shielding layer made of black ink, it can be used as a light-shielding tape, and if it is a light-reflecting layer made of white ink, it can be used as a light reflection tape. Further, a combination of the two is used, or a light-reflective white film or a light-shielding black film is used on the resin film to be used, and a light-reflecting layer composed of a light-shielding layer or a white ink formed by the black ink is used. The combination can also be used as a light-shielding reflection band.

[use]

The double-sided adhesive tape of the present invention is used for fixing an optical film, fixing an optical film and other members, and the above-mentioned water-dispersed acrylic system The adhesive layer formed of the adhesive composition is attached to the optical film and used. The adhesive tape of the present invention has a suitable adhesive force to the adherend, and after fixing the optical film and other members, the distortion of the optical film can be suppressed even when the optical film is deformed, so that it is suitable for the optical film and other members. Fixed image display device. Moreover, it has good adhesion, and is excellent in resistance to repulsion. Therefore, it is possible to use a thin film which is easy to cause distortion of an optical film and which is likely to cause peeling of the adhesive tape due to deformation of the casing or the like, and is particularly thin in shape. A component fixing tape used for fixing an optical film of an image display device. Further, it is also possible to suitably use a light-shielding tape, a light reflection tape, and a light-shielding reflection tape of an optical film and a transparent panel of a fixed-thickness image display device which is required to have a suitable light-shielding property and which requires reworkability at the time of failure or repair.

Examples of the optical film include a ruthenium sheet, a diffusion film, a light-shielding film, and a reflective film. Among them, in particular, as an optical film which is susceptible to distortion, a ruthenium having a ruthenium layer on a film having a polarized reflection function can be cited. Examples of such an optical film include BEF-RP2RC and BEF-RP3 manufactured by 3M Company.

The double-sided adhesive tape of the present invention can suitably suppress the distortion of the optical film, and in particular, an optical film having a size of about 2.5 to 7 angstroms (diagonally) of the optical film can achieve an appropriate distortion suppressing effect.

The larger the shape change rate of the optical film, the more easily the distortion occurs, and the distortion is severe when the behavior changes in the flow direction and the width direction. a rate of change greater than ±0.05% in the flow direction or width direction, especially a rate of change greater than +0.06% in the flow direction, -0.06% in the width direction Distortion is particularly prone to occur at large rate of change. According to the adhesive tape of the present invention, even if it is the above optical film, distortion can be suppressed. Further, the rate of change in the shape of the optical film was expressed by the following formula before and after standing at 85 ° C for 5 minutes.

Shape change rate = [(length after standing - length before standing) / (length before standing)] × 100 (%)

When the optical film has a ruthenium layer and the ridge line of the ruthenium layer is obliquely intersected with the flow direction of the adhesive tape, the distortion of the optical film is likely to occur. However, the adhesive tape of the present invention can appropriately suppress the distortion even in the above configuration.

Other members that are fixed to the optical film by the double-sided adhesive tape of the present invention may be various members that are fixed to the optical film in the image display device, and for example, liquid crystal (LCD) provided on the surface layer of the image display device. A display panel such as a panel, an electroluminescence panel, a plasma display panel, or an electronic paper display panel. These display panels can be used alone or in combination with a functional film such as a polarizing film. In the double-sided adhesive tape of the present invention, when both surfaces are used as the adhesive layer of the water-dispersible acrylic adhesive composition, the adhesion to the glass panel or the polarizing film is particularly excellent.

The fixed aspect of the optical film and the other member is not particularly limited as long as it can secure the image display area of the image display device, and is preferably a double-sided frame-like shape by punching or the like. The adhesive tape is used to fix the square optical film and other components. The rectangular double-sided adhesive tape is used to fix the peripheral portion of the square optical film on both sides of the edge, with an arbitrary gap in the square. Optics The peripheral portion of the end portion of the film is fixed by a small-sized double-sided adhesive.

An example of the image display device is a backlight LCD or the like. The general structure is a laminated reflector, a light guide plate, a diffusion sheet, etc., and an optical film such as a cymbal is provided on the surface layer, and a lamp reflector is disposed on the side of the light guide plate. A backlight module in which a light source such as an LED (Light Emitting Diode) or a cold cathode tube is laminated, and a display panel (LCD panel) are laminated. The adhesive tape of the present invention can be exemplified as a preferred aspect between the display panel and the optical film on the surface of the backlight module, which is punched into a frame shape and sandwiched. The adhesive form of the double-sided adhesive tape can be an optical film side adhesive layer of the double-sided adhesive tape which only contacts the optical film of the surface layer of the backlight module, or can be an optical film on the surface of the backlight module and accommodates the optical film. The form of the jumper on the housing of the backlight module.

The double-sided adhesive tape for fixing a glass panel optical film of the present invention can be used as a variety of electronic devices, in particular, electronic notebooks, mobile phones, and smart phones, because it can suppress the malfunction of peripheral devices and provide a highly reliable product. A high-performance mobile phone), a PHS, a game machine, an electronic book, a multi-function data terminal, a mobile personal computer, or the like, is used for fixing a glass panel of a display device that carries an electronic device.

Example [Production Example of Polyester Aminoformate] (Polyester urethane resin (A))

In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube, 256.3 parts of an acid component of adipic acid/terephthalic acid = 50/50 and 3-methyl-1,5-pentane were added. Average number of points obtained from alcohol A polyester diol having a submount (hereinafter referred to as Mn) of 2,000 and 36.5 parts of isophorone diisocyanate were reacted at 90 ° C for 15 hours under a nitrogen stream. Next, 5.0 parts of isophorone diamine, 2.2 parts of di-n-butylamine, 175 parts of toluene, 350 parts of methyl ethyl ketone, and 175 parts of isopropenol were added, and the reaction was carried out at 40 ° C with stirring. After 3 hours, a polyester urethane resin (A) having a resin solid content concentration of 30.0%, a Gardner viscosity UV (25 ° C), an amine price = 0, and a mass average molecular weight (hereinafter referred to as Mw) of 67,000 was obtained. The peak temperature of tan δ of the obtained resin was -8 °C.

[Manufacturing example of black ink] (Manufacturing Example 1 of Black Ink)

4 parts of "Carbon Degussa Special 4A" manufactured by DEGUSSA, 6 parts of "Carbon Special 250P" manufactured by DEGUSSA, and 40 parts of polyester urethane resin (A) (tan δ peak temperature = -8 ° C) 23 parts of methyl ethyl ketone, 13 parts of toluene, 6 parts of ethyl acetate, 3 parts of n-propyl acetate, 3 parts of isopropyl alcohol, wet-dispersed in a sand mill for about 1 hour In addition, four parts of DIC company hardener "KR90" (biuret body of hexamethylene diisocyanate) and 35 parts of DIC company diluent "Direuser V No. 20" were added, and black ink (A) was prepared. ). Further, the resin represents a solid content ratio.

[Production of support] (Ink coated film (A))

Teflex FW2 #13 (thickness: 13 μm, tensile strength: 23 N/20 mm) manufactured by Teijin DuPont Film Co., Ltd., and corona treatment was carried out in such a manner that the surface state became 50 dynes or more, and the dry thickness was 4 μm. 2 times gravure coated black ink (A). Further, the drying was allowed to stand at room temperature for 2 minutes. Then, it was aged at 40 ° C for 2 days to obtain an ink-coated film (A).

[Modulation method of acrylic copolymer emulsion] (Modulation example 1) <Preparation of Emulsion (1)>

75.0 g of ion-exchanged water, 20.0 g of surfactant Aqualon KH-1025 [manufactured by Daiichi Kogyo Co., Ltd.; 25% active ingredient] and 37.5 g of surfactant, Latemul PD-104 [King] were placed in the container. (share) system; active ingredient 20%], evenly dissolved. Thereto, 227.5 g of n-butyl acrylate, 227.5 g of 2-ethylhexyl acrylate, 25.0 g of methyl methacrylate, 7.5 g of N-vinylpyrrolidone, 1.5 g of acrylic acid, and 11.0 were added. G-acrylic acid and 0.2 g of lauryl mercaptan were emulsified to obtain 632.7 g of an emulsion (1).

<Preparation of Emulsion of Acrylic Copolymer (1)>

In a reaction vessel equipped with a stirrer, a reflux cooling tube, a nitrogen gas introduction tube, a thermometer, and a dropping funnel, 340 g of ion-exchanged water was placed, and the temperature was raised to 60 ° C while blowing nitrogen gas. A portion of the emulsion (1) [3.2 g], 5.0 g of an aqueous ammonium persulfate solution [3% active ingredient], and 5.0 g of an aqueous sodium hydrogen sulfite solution [3% active ingredient] were added while stirring, while maintaining 60 ° C. The polymerization was carried out for 1 hour. Subsequently, 629.5 g of the remaining emulsion (1) and 40 g of an aqueous ammonium persulfate solution (1.25% active ingredient) were used, and the reaction vessel was kept at 60 ° C for 8 hours while using a separate funnel. After the completion of the dropwise addition, the reaction vessel was stirred at 60 ° C for 2 hours, and then the contents were cooled, followed by preparation with aqueous ammonia (active ingredient: 10%) so that the pH became 7.5. This was filtered with a 200 mesh metal mesh to obtain 1013.5 g of an emulsion of the acrylic copolymer (1). Here, the obtained acrylic copolymer (1) had an emulsion solid content concentration of 50% and an average particle diameter of 341 nm.

(Modulation example 2) <Preparation of Emulsion (2)>

75.0 g of ion-exchanged water, 20.0 g of surfactant Aqualon KH-1025 [manufactured by Daiichi Kogyo Co., Ltd.; 25% active ingredient] and 37.5 g of surfactant, Latemul PD-104 [King] were placed in the container. (share) system; active ingredient 20%], evenly dissolved. Thereto, 227.5 g of n-butyl acrylate, 227.5 g of 2-ethylhexyl acrylate, 25.0 g of methyl methacrylate, 7.5 g of N-vinylpyrrolidone, 12.5 g of acrylic acid, 0.20 were added. The lauryl mercaptan of g was emulsified to obtain 632.7 g of an emulsion (2).

<Preparation of Emulsion of Acrylic Copolymer (2)>

In a reaction vessel equipped with a stirrer, a reflux cooling tube, a nitrogen gas introduction tube, a thermometer, and a dropping funnel, 340 g of ion-exchanged water was placed, and the temperature was raised to 60 ° C while blowing nitrogen gas. A portion of the emulsion (2) [3.2 g], 5.0 g of an aqueous ammonium persulfate solution [3% active ingredient], and 5.0 g of an aqueous sodium hydrogen sulfite solution [3% active ingredient] were added while stirring, while maintaining 60 ° C The polymerization was carried out for 1 hour. Subsequently, 629.5 g of the remaining emulsion (2) and 40 g of an aqueous ammonium persulfate solution (1.25% of active ingredient) were used, and the reaction vessel was kept at 60 ° C for 8 hours while using a separate funnel. After the completion of the dropwise addition, the reaction vessel was stirred at 60 ° C for 2 hours, and then the contents were cooled, followed by preparation with aqueous ammonia (active ingredient: 10%) so that the pH became 7.5. This was filtered with a 200 mesh metal mesh to obtain 1013.5 g of an emulsion of the acrylic copolymer (2). Here, the obtained acrylic copolymer (2) had an emulsion solid content concentration of 50% and an average particle diameter of 338 nm.

(Modulation Example 3) <Preparation of Emulsion (3)>

75.0 g of ion-exchanged water, 20.0 g of surfactant Aqualon KH-1025 [manufactured by Daiichi Kogyo Co., Ltd.; 25% active ingredient] and 37.5 g of surfactant, Latemul PD-104 [King] were placed in the container. (share) system; active ingredient 20%], evenly dissolved. Thereto, 50.0 g of n-butyl acrylate, 405.0 g of 2-ethylhexyl acrylate, 25.0 g of methyl methacrylate, 7.5 g of N-vinylpyrrolidone, 12.5 g of acrylic acid, 0.20 were added. The lauryl mercaptan of g was emulsified to obtain 632.7 g of an emulsion (3).

<Preparation of Emulsion of Acrylic Copolymer (3)>

In a reaction vessel equipped with a stirrer, a reflux cooling tube, a nitrogen gas introduction tube, a thermometer, and a dropping funnel, 340 g of ion-exchanged water was placed, and the temperature was raised to 60 ° C while blowing nitrogen gas. A portion of the emulsion (3) [3.2 g], 5.0 g of an aqueous ammonium persulfate solution [3% active ingredient], and 5.0 g of an aqueous sodium hydrogen sulfite solution [3% active ingredient] were added while stirring, while maintaining 60 ° C The polymerization was carried out for 1 hour. Subsequently, 629.5 g of the remaining emulsion (1) and 40 g of an aqueous ammonium persulfate solution (1.25% active ingredient) were used, and the reaction vessel was kept at 60 ° C for 8 hours while using a separate funnel. After the completion of the dropwise addition, the reaction vessel was stirred at 60 ° C for 2 hours, and then the contents were cooled, followed by preparation with aqueous ammonia (active ingredient: 10%) so that the pH became 7.5. This was filtered with a 200 mesh metal mesh to obtain 1013.5 g of an emulsion of the acrylic copolymer (3). Here, the obtained acrylic copolymer (3) had an emulsion solid content concentration of 50% and an average particle diameter of 330 nm.

(Adjustment example 4) <Preparation of Emulsion (4)>

75.0 g of ion-exchanged water, 20.0 g of surfactant Aqualon KH-1025 [manufactured by Daiichi Kogyo Co., Ltd.; 25% active ingredient] and 37.5 g of surfactant, Latemul PD-104 [King] were placed in the container. (Stock) system active ingredient 20%], evenly dissolved. Thereto, 231.25 g of n-butyl acrylate, 231.25 g of 2-ethylhexyl acrylate, 25.0 g of methyl methacrylate, 1.5 g of acrylic acid, 11.0 g of methacrylic acid, and 0.2 g of lauryl were added. The thiol was emulsified to obtain 632.7 g of an emulsion (4).

<Preparation of Emulsion of Acrylic Copolymer (4)>

In a reaction vessel equipped with a stirrer, a reflux cooling tube, a nitrogen gas introduction tube, a thermometer, and a dropping funnel, 340 g of ion-exchanged water was placed, and the temperature was raised to 60 ° C while blowing nitrogen gas. A portion of the emulsion (4) [3.2 g], 5.0 g of an aqueous ammonium persulfate solution [3% active ingredient], and 5.0 g of an aqueous solution of sodium hydrogen sulfite [3% active ingredient] were added while stirring, while maintaining 60 ° C The polymerization was carried out for 1 hour. Subsequently, 629.5 g of the remaining emulsion (2) and 40 g of an aqueous ammonium persulfate solution (1.25% of active ingredient) were used, and the reaction vessel was kept at 60 ° C for 8 hours while using a separate funnel. After the completion of the dropwise addition, the reaction vessel was stirred at 60 ° C for 2 hours, and then the contents were cooled, followed by preparation with aqueous ammonia (active ingredient: 10%) so that the pH became 7.5. This was filtered with a 200 mesh metal mesh to obtain 1013.5 g of an emulsion of the acrylic copolymer (4). Here, the obtained acrylic copolymer (4) had an emulsion solid content concentration of 50% and an average particle diameter of 345 nm.

(Adjustment example 5) <Preparation of Emulsion (5)>

75.0 g of ion-exchanged water, 20.0 g of surfactant Aqualon KH-1025 [manufactured by Daiichi Kogyo Co., Ltd.; 25% active ingredient] and 37.5 g of surfactant, Latemul PD-104 [King] were placed in the container. (share) system; active ingredient 20%], evenly dissolved. Thereto, 240 g of n-butyl acrylate, 240 g of 2-ethylhexyl acrylate, 7.5 g of N-vinylpyrrolidone, 1.5 g of acrylic acid, 11.0 g of methacrylic acid, and 0.2 g of lauryl were added. The mercaptan was emulsified to obtain 632.7 g of an emulsion (5).

<Preparation of Emulsion of Acrylic Copolymer (4)>

In a reaction vessel equipped with a stirrer, a reflux cooling tube, a nitrogen gas introduction tube, a thermometer, and a dropping funnel, 340 g of ion-exchanged water was placed, and the temperature was raised to 60 ° C while blowing nitrogen gas. A portion of the emulsion (5) [3.2 g], 5.0 g of an aqueous ammonium persulfate solution [3% active ingredient], and 5.0 g of an aqueous sodium hydrogen sulfite solution [3% active ingredient] were added while stirring, while maintaining 60 ° C The polymerization was carried out for 1 hour. Subsequently, 629.5 g of the remaining emulsion (2) and 40 g of an aqueous ammonium persulfate solution (1.25% of active ingredient) were used, and the reaction vessel was kept at 60 ° C for 8 hours while using a separate funnel. After the completion of the dropwise addition, the reaction vessel was stirred at 60 ° C for 2 hours, and then the contents were cooled, followed by preparation with aqueous ammonia (active ingredient: 10%) so that the pH became 7.5. This was filtered with a 200 mesh metal mesh to obtain 1013.5 g of an emulsion of the acrylic copolymer (5). Here, the obtained acrylic copolymer (5) had an emulsion solid content concentration of 50% and an average particle diameter of 340 nm.

[Manufacture of water-dispersed acrylic adhesive composition] (Manufacturing Example 1)

To 1000 g [dry; 500 g] of the emulsion of the acrylic copolymer (1) described above, 2.5 g of Surfynol PSA-336 as a leveling agent [manufactured by Air Products Japan Co., Ltd.; active ingredient 100%], 2.5 g was added. Surfynol DF-110D [Air Products Japan Co., Ltd.; active ingredient 100%] as an antifoaming agent, and 125 g of Super Ester NS-100H as a tackifying resin based on solid content [Arakawa Chemical Industry Co., Ltd.; Epoxy compound Tetrad C [manufactured by Mitsubishi Gas Chemical Co., Ltd.] as a crosslinking agent at a glass transition temperature of 50 ° C] and 0.15 g (0.03 parts by mass), which was filtered with a 200 mesh metal mesh to obtain a water-dispersed acrylic acid. Adhesive composition (1).

(Manufacturing Example 2)

A water-dispersible acrylic pressure-sensitive adhesive composition (2) was produced in the same manner as in Production Example 1 except that 0.15 g (0.03 parts by mass) of the crosslinking agent in Production Example 1 was 0.2 g (0.04 parts by mass). .

(Manufacturing Example 3)

A water-dispersible acrylic pressure-sensitive adhesive composition (3) was produced in the same manner as in Production Example 1, except that 0.15 g (0.03 parts by mass) of the crosslinking agent in Production Example 1 was 0.25 g (0.05 parts by mass). .

(Manufacturing Example 4)

In place of 125 g of the solid component of the tackifying resin Super Ester NS-100H used in Production Example 1, 62.5 g of Super Ester E-865NT (manufactured by Arakawa Chemical Industries Co., Ltd.; glass transition temperature of 100 ° C) was used. 62.5 g of Super Ester E-200NT (made by Arakawa Chemical Industry Co., Ltd.; glass transition temperature of 90 ° C) A water-dispersible acrylic pressure-sensitive adhesive composition (4) was produced in the same manner as in Production Example 1, except that the amount of the crosslinking agent was 0.15 g (0.03 parts by mass), which was 0.35 g (0.07 parts by mass).

(Manufacturing Example 5)

A water-dispersed acrylic adhesive was produced in the same manner as in Production Example 3, except that 1000 g of the emulsion of the acrylic copolymer (1) used in Production Example 3 (dry; 500 g) was used instead of the above-described acrylic copolymer (2). Agent composition (5).

(Manufacturing Example 6)

A water-dispersible acrylic pressure-sensitive adhesive composition (6) was produced in the same manner as in Production Example 5 except that the amount of the crosslinking agent in the production example 5 was 0.25 g (0.05 parts by mass) of 0.4 g (0.08 parts by mass). .

(Manufacturing Example 7)

A water-dispersed acrylic adhesive was produced in the same manner as in Production Example 6, except that 1000 g of the emulsion of the acrylic copolymer (2) used in Production Example 6 (dry; 500 g) was used instead of the above-described acrylic copolymer (3). Composition (7).

(Manufacturing Example 8)

A water-dispersible acrylic pressure-sensitive adhesive composition (8) was produced in the same manner as in Production Example 7, except that 0.4 g (0.08 parts by mass) of the crosslinking agent in the production example 7 was 0.5 g (0.1 part by mass). .

(Manufacturing Example 9)

In place of 125 g of the solid component of the tackifying resin Super Ester NS-100H used in Production Example 1, 125 g of Super Ester E-200NT in terms of solid content was used [Arakawa Chemical Industry Co., Ltd.; glass transfer temperature] A water-dispersible acrylic pressure-sensitive adhesive composition (9) was produced in the same manner as in Production Example 1, except that the amount of the crosslinking agent was 0.15 g (0.03 parts by mass) of 0.35 g (0.07 parts by mass).

(Manufacturing Example 10)

In place of 125 g of the solid content of the tackifying resin Super Ester NS-100H used in Production Example 1, 125 g of Super Ester E-865NT (manufactured by Arakawa Chemical Co., Ltd.; glass transition temperature: 100 ° C) in terms of solid content was used. A water-dispersed acrylic pressure-sensitive adhesive composition (10) was produced in the same manner as in Production Example 1, except that 0.15 g (0.03 parts by mass) of the crosslinking agent was used in an amount of 0.35 g (0.03 parts by mass).

(Manufacturing Example 11)

In addition to the use of 50 g of the tackifying resin Super Ester NS-100H solid content used in the production example 1, the amount of the crosslinking agent is 0.15 g (0.03 part by mass) of 0.35 g (0.07 part by mass), and the production example is used. In the same manner, a water-dispersible acrylic pressure-sensitive adhesive composition (11) was produced.

(Manufacturing Example 12)

In addition to the use of 200 g of the tackifying resin super Ester NS-100H solid component used in the production example 1, the amount of the crosslinking agent is 0.15 g (0.03 part by mass) of 0.5 g (0.1 part by mass), and the production example is used. In the same manner, a water-dispersed acrylic pressure-sensitive adhesive composition (12) was produced.

(Manufacturing Example 13)

A water-dispersed acrylic adhesive was produced in the same manner as in Production Example 4, except that 1000 g of the emulsion of the acrylic copolymer (1) used in Production Example 4 (dry; 500 g) was used, except that the acrylic copolymer (4) described above was used. Composition (13).

(Manufacturing Example 14)

A water-dispersed acrylic adhesive was produced in the same manner as in Production Example 4, except that 1000 g of the emulsion of the acrylic copolymer (1) used in Production Example 4 (dry; 500 g) was used instead of the above-described acrylic copolymer (5). Composition (14).

(Comparative Manufacturing Example 1)

A water-dispersible acrylic pressure-sensitive adhesive composition (H1) was produced in the same manner as in Production Example 4 except that the amount of the crosslinking agent in the production example 4 was 0.35 g (0.07 parts by mass) of 0.15 g (0.03 parts by mass). .

(Comparative Manufacturing Example 2)

A water-dispersible acrylic pressure-sensitive adhesive composition (H2) was produced in the same manner as in Production Example 1 except that the amount of the crosslinking agent in the production example 1 was 0.15 g (0.03 parts by mass) of 0.4 g (0.08 parts by mass). .

(Comparative Manufacturing Example 3)

A water-dispersible acrylic pressure-sensitive adhesive composition (H3) was produced in the same manner as in Production Example 5 except that the amount of the crosslinking agent in the production example 5 was 0.25 g (0.05 parts by mass) of 0.15 g (0.03 parts by mass). .

(Comparative Manufacturing Example 4)

A water-dispersible acrylic pressure-sensitive adhesive composition (H4) was produced in the same manner as in Production Example 5 except that the amount of the crosslinking agent in the production example 5 was 0.25 g (0.05 parts by mass) of 0.2 g (0.04 parts by mass). .

(Comparative Manufacturing Example 5)

A water-dispersible acrylic pressure-sensitive adhesive composition (H5) was produced in the same manner as in Production Example 5 except that the amount of the crosslinking agent in the production example 5 was 0.25 g (0.05 parts by mass) of 0.5 g (0.1 part by mass). .

(Comparative Manufacturing Example 6)

A water-dispersible acrylic pressure-sensitive adhesive composition (H6) was produced in the same manner as in Production Example 7, except that the amount of the crosslinking agent in the production example 7 was 0.4 g (0.08 parts by mass) of 0.6 g (0.03 parts by mass). .

[Production of adhesive tape] (Example 1)

The water-dispersed acrylic pressure-sensitive adhesive composition (1) obtained in Production Example 1 was applied onto a polyester film having a thickness of 75 μm which had been subjected to release treatment so as to have a thickness of 20 μm after drying, and dried at 85 ° C for 2 minutes. An adhesive layer is obtained. The obtained adhesive layer was transferred to both sides of the ink-coated film (A), laminated with a hot roll of 80 ° C at a pressure of 4 kgf / cm, and further aged at 40 ° C for 2 days to obtain a double of Example 1. Adhesive tape.

(Examples 2 to 14)

The double-sided adhesive tapes of Examples 2 to 14 were obtained in the same manner as in Example 1 except that the water-dispersible acrylic pressure-sensitive adhesive compositions (2) to (14) obtained in Production Examples 2 to 14 were used.

(Comparative examples 1 to 6)

The double-sided adhesive tapes of Comparative Examples 1 to 6 were obtained in the same manner as in Example 1 except that the water-dispersible acrylic pressure-sensitive adhesive compositions (H1) to (H6) obtained in Comparative Production Examples 1 to 6 were used.

The adhesive composition and the adhesive tape obtained in the above Examples 1 to 8 and Comparative Examples 1 to 6 were evaluated as follows. The results are shown in the table.

(Measurement of glass transition temperature of acrylic copolymer)

An emulsion of an acrylic copolymer was used to form a sheet in accordance with the production conditions of the above-mentioned pressure-sensitive adhesive tape, and laminated to a thickness of 5 mm to prepare a test piece. Using a viscoelasticity tester (manufactured by Rheometrics Co., Ltd., trade name: Ares 2KFRTN1), a test piece was sandwiched between parallel disks of the measuring unit of the test machine, and measured at a frequency of 1 Hz and a temperature increase rate of 2 ° C/min. The storage elastic modulus (G') and the loss elastic modulus (G") from 50 ° C to 150 ° C were calculated as tan δ according to the following formula as the glass transition temperature.

(Measurement of glass transition temperature of tackifying resin)

Using a vacuum dryer, the tackifying resin was dried at 60 ° C for 2 days or more under vacuum to obtain a test sample having a dry weight of 10 mg. For the test sample, a DSC measuring device (manufactured by Mettler-Toledo Co., Ltd., trade name: DSC822) was used, and the DSC curve was measured twice at a temperature rising rate of 2 ° C/min in a temperature range of -50 ° C to 200 ° C. The glass transition temperature was measured from the second measurement data.

(Measurement of glass transition temperature of adhesive layer)

The adhesive layer formed in accordance with the above-described manufacturing conditions of the adhesive tape was laminated to a thickness of 5 mm to prepare a test piece. Using a viscoelasticity tester (manufactured by Rheometrics Co., Ltd., trade name: Ares 2KFRTN1), a test piece was sandwiched between parallel disks of the measuring unit of the test machine, and measured at a frequency of 1 Hz and a temperature increase rate of 2 ° C/min. The storage elastic modulus (G') and the loss elastic modulus (G") from 50 ° C to 150 ° C were calculated as tan δ according to the following formula as the glass transition temperature.

Tan δ=G”/G’

(Measurement of gel fraction of adhesive layer)

According to the production conditions of the above-mentioned pressure-sensitive adhesive tape, the thickness of the dried tape was set to 25 μm, and the film was placed on a polyester film (with a release treatment) to prepare a test piece. The test piece was cut into a size of 20 mm × 100 mm, and the polyester film was peeled off, and the weight a before the toluene extraction was measured. Next, the same test piece was immersed in toluene for 24 hours, and then the gel was taken out and dried at 100 ° C for 2 hours, and the weight b after toluene extraction was measured. The gel fraction is calculated by the following calculation formula.

Gel fraction (%) = (b / a) × 100

(undulation/distortion test of optical film)

The black ink side of the frame-shaped adhesive tape (outer shape: 32 mm × 42 mm, width: 2 mm) of the first figure obtained by punching and processing the above-mentioned prepared adhesive tape at 23 ° C was attached to the glass. The white ink side was attached to a thin optical film "BEFRP2RC" (120 μm) manufactured by 3M Company (outer shape: 30 mm × 40 mm, shape change rate / flow direction when standing in a dryer at 85 ° C for 5 minutes: +0.08% , width direction: -0.08%) (Fig. 1). Furthermore, the width of the adhesive tape in contact with the optical film is 1 mm on each side. The part was allowed to stand at 85 ° C for 72 hours, and then allowed to stand at 23 ° C for 1 hour, and the change in appearance before and after standing at 85 ° C was observed.

○: No distortion occurred in the optical film

△: Distortion in the optical film

×: Large distortion occurs in the optical film

(anti-repellency test)

As shown in Fig. 2, a 100 μm PET film (Emblet SA #100 made by UNITIKA) and a polycarbonate of 2 mm thickness are attached with a 3 mm wide adhesive tape. Ester (PC) board. Then, the mixture was pressurized under the condition of a round trip of 2 kg of the rolls, and the floating peeling after standing at 60 ° C for 90 hours of RH was observed. When the floating of 0.5 mm or more occurs, the thickness difference is serious, and it is not suitable for the adhesive tape for fixing the liquid crystal module.

○: Float and peel off to less than 0.5mm

×: float and peel off to 0.5mm or more

As is apparent from the above Tables 1 to 3, the adhesive tapes of the present invention of Examples 1 to 14 can suitably suppress the undulation or distortion of the optical film, and have good resistance, although the VOC-reducing water-based adhesive is used. Repulsive. On the other hand, the adhesive tape system of the comparative example cannot achieve both the suppression of the undulation or distortion of the optical film and the repellency resistance.

10‧‧‧Double adhesive tape

11‧‧‧Optical film

12‧‧‧ glass

20‧‧‧Adhesive tape

21‧‧‧PC board

22‧‧‧PET film

23‧‧‧ Double-sided tape

Fig. 1 (a) and (b) are conceptual diagrams showing a method of measuring the distortion preventing property of the optical film in the embodiment.

Fig. 2 is a conceptual diagram showing a method of measuring the anti-repellency in the examples.

Claims (4)

An adhesive tape for use in a fixed adhesive tape for an optical film, characterized in that the adhesive layer that is in contact with the optical film is an adhesive layer composed of a water-dispersed acrylic adhesive composition, the adhesive The glass transition temperature of the layer is below -5 ° C, the gel fraction is 25 to 45%, and the water-dispersed acrylic adhesive composition contains an acrylic copolymer having a glass transition temperature of -45 to -25 ° C and a glass transition temperature. It is a tackifying resin of 30~120 °C. The adhesive tape of claim 1, wherein the content of the tackifying resin is from 10 to 40 parts by mass based on 100 parts by mass of the acrylic copolymer. The adhesive tape of the first aspect of the invention, wherein the acrylic copolymer contains 40% by mass or more of 2-ethylhexyl acrylate in the monomer component used in the acrylic copolymer. The adhesive tape of claim 1, wherein the optical film is a cymbal.