JP2013177485A - Optical adhesive and optical filter for hard transparent plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical adhesive giving an adhesive layer, even on impressing compression force locally, capable of easily restoring its thickness to a state before the pressurization when the compression force is released.SOLUTION: This optical adhesive having a ≤0.30 loss tangent and also a ≥0.13 MPa storage modulus at 25°C, and containing pigment includes a component based on an acrylic polymer having a ≥1,500,000 weight-average molecular weight and a ≥-50°C glass transition temperature, and a tackifier resin. Preferably, a reactive functional group in the acrylic polymer is reacted with a crosslinking agent to form a crosslinked structure.

Description

  The present invention relates to an optical pressure-sensitive adhesive. Specifically, the present invention relates to an optical pressure-sensitive adhesive interposed between a hard transparent plate such as a top glass of a plasma display panel module and a flexible film such as a functional resin film.

  The plasma display panel is broadly divided into a module that is a light emitting unit, and a front panel that is placed on the front (outside) of the module to block unnecessary light emitted from the module and prevent reflection of external light to improve visibility. It consists of a filter.

  The front filter is composed of a number of films having various functions and an adhesive layer for bonding the films or the front filter and the top glass of the module. Reducing the overall thickness of the plasma display panel and reducing its manufacturing cost is a permanent issue in this panel, and the front filter is also reduced in thickness to achieve this issue. Or simplifying its configuration.

  As one of means for that purpose, Patent Document 1 uses an optical pressure-sensitive adhesive in which a dye is contained in a pressure-sensitive adhesive, so that the dye layer and the pressure-sensitive adhesive layer in the conventional structure are integrated, and the configuration of the front filter. A method is disclosed that simplifies the process and copes with thinning. This dye may be used for the purpose of color correction in the visible light region, or may be used for the purpose of suppressing near infrared rays from being emitted from the front surface of the plasma display.

JP 2003/082302 A

  After a front filter is attached to the top glass of the module using an adhesive layer made of an optical adhesive, the resulting plasma display panel may be transported until the next step. In the course of this conveyance, a person or an object may collide with the exposed surface of the front filter (hereinafter also referred to as “filter front surface”), and even if the application of the local pressure based on this collision is canceled, The deformation of the pressure-sensitive adhesive layer generated due to the pressurization may not be recovered, and a portion where the thickness of the pressure-sensitive adhesive layer is locally thin may occur (hereinafter, this phenomenon is also referred to as “thinning”). When the pressure-sensitive adhesive layer contains a pigment as described above, a region where the transmittance has changed corresponding to the thinned portion (thinned portion) of the pressure-sensitive adhesive layer on the front surface of the filter, a so-called color loss region Occurs.

  Therefore, the present invention provides an optical pressure-sensitive adhesive that provides a pressure-sensitive adhesive layer whose thickness can be easily restored to the state before pressure application when the pressure is released even when a pressure force is applied locally. The purpose is to provide.

  As a result of studies by the present inventors in order to solve the above-mentioned problems, a pressure-sensitive adhesive comprising the optical pressure-sensitive adhesive is controlled by controlling the relationship between the storage elastic modulus and loss elastic modulus of the optical pressure-sensitive adhesive within a predetermined range. It was found that the occurrence of thinning can be suppressed in the layer.

  Further, in order to obtain an optical pressure-sensitive adhesive whose properties relating to the elastic modulus are controlled, the glass transition temperature and the weight average molecular weight as a main component of the constituent material of the optical pressure-sensitive adhesive are not less than a predetermined threshold value. It was also found that it is preferable to use an acrylic polymer.

  Further, when the optical pressure-sensitive adhesive contains a tackifier resin containing an acid-modified rosin together with a cross-linking agent, not only the properties relating to the elastic modulus of the optical pressure-sensitive adhesive are appropriately controlled but also the optical pressure-sensitive adhesive. It became easy to control the adhesiveness of the adhesive layer to glass within a range excellent in reworkability, and the knowledge that it was particularly preferable was also obtained.

  The present invention completed based on these findings is, firstly, an optical pressure-sensitive adhesive containing a dye, having a loss tangent at 25 ° C. of 0.30 or less and a storage elastic modulus at 25 ° C. of 0.1. An optical pressure-sensitive adhesive having a pressure of 13 MPa or more is provided (Invention 1).

  Such an optical pressure-sensitive adhesive has a storage elastic modulus and a loss elastic modulus set in appropriate ranges, so that a local load is applied in the thickness direction to the pressure-sensitive adhesive layer made of the optical pressure-sensitive adhesive. However, the deformation in the thickness direction is difficult to occur, and even if the deformation occurs, the thickness of the pressure-sensitive adhesive layer can be easily restored to the state before the load is applied if the application of the load is released. Therefore, it is possible to obtain an adhesive layer in which thinning is unlikely to occur.

  In the said invention (invention 1), it is preferable to contain the component based on the acrylic polymer whose weight average molecular weight is 1,500,000 or more and whose glass transition temperature is -50 degreeC or more (invention 2). When the weight average molecular weight is 1,500,000 or more, the storage elastic modulus and the loss elastic modulus can be easily within the above ranges. Moreover, when the glass transition temperature is −50 ° C. or higher, the fluidity of the optical pressure-sensitive adhesive in the operating temperature range is hardly increased. Therefore, it is difficult for the pressure-sensitive adhesive layer made of this optical pressure-sensitive adhesive to be thinned.

  In the said invention (invention 1 and 2), it is preferable that the optical adhesive further contains tackifying resin (invention 3). By containing the tackifying resin, the optical pressure-sensitive adhesive is easily hardened. The tackifying resin preferably has a softening point of 80 ° C. or higher as measured by the ring and ball method.

  Secondly, the present invention provides an optical pressure-sensitive adhesive containing a component based on an acrylic polymer having a weight average molecular weight of 1.5 million or more and a glass transition temperature of −50 ° C. or more, and a tackifying resin. (Invention 4). Such an optical pressure-sensitive adhesive can easily satisfy the storage elastic modulus and loss elastic modulus described in the above invention, and the pressure-sensitive adhesive layer made of the optical pressure-sensitive adhesive is less likely to be thinned.

  In the said invention (invention 2-4), the said acrylic polymer is 50 masses of (meth) acrylic-acid alkylesters whose alkyl group is C1-C18 as a monomer which comprises the said acrylic polymer. % Or more and 99.9% by mass or less, and (meth) acrylic acid ester having a reactive functional group is contained in an amount of 0.1% by mass or more and 10% by mass or less, and the acrylic polymer is a crosslinking agent in the reactive functional group. It is preferable to form a crosslinked structure by reacting with (Invention 5). By having such a composition, the optical pressure-sensitive adhesive is easily hardened, and thinning of the pressure-sensitive adhesive layer made of the optical pressure-sensitive adhesive is difficult to occur.

  In the said invention (invention 5), it is preferable that the said crosslinking agent contains an isocyanate type crosslinking agent (invention 6). Since the isocyanate-based crosslinking agent can easily control the crosslinking reaction, it becomes easy to satisfy the conditions of the storage elastic modulus and the loss elastic modulus described in the above invention for the optical pressure-sensitive adhesive.

  In the said invention (invention 3 to 6), it is preferable that the said tackifying resin contains an acid-modified rosin (invention 7). In addition to the fact that the tackifying resin is hard, the optical pressure-sensitive adhesive is easily hardened by the carboxyl group portion of the acid-modified rosin accelerating the formation of a crosslinked structure by the crosslinking agent.

  In the said invention (invention 7), it is preferable that the acid value of the said acid-modified rosin is 200 KOHmg / g or more (invention 8). When the acid value is 200 KOH mg / g or more, the effect of containing the acid-modified rosin can be obtained more stably.

  In the above inventions (Inventions 1 to 8), a pressure-sensitive adhesive layer made of the optical pressure-sensitive adhesive and having a thickness of 25 μm is formed on a substrate made of a 100 μm polyethylene terephthalate film to produce a pressure-sensitive adhesive sheet. It is preferable that the adhesive strength of the pressure-sensitive adhesive sheet to the soda-lime glass when the surface on the pressure-sensitive adhesive layer side is attached to soda-lime glass is 10 N / 25 mm or less (Invention 9). When the adhesive strength is 10 N / 25 mm or less, the reworkability of the pressure-sensitive adhesive sheet (that the pressure-sensitive adhesive can be removed without causing adherend contamination when adhesion of the pressure-sensitive adhesive is lost) is improved.

  In the said invention (invention 1-9), it is preferable that the optical adhesive is for interposing between a hard transparent plate and a flexible film (invention 10). As described above, since the pressure-sensitive adhesive layer made of the optical pressure-sensitive adhesive according to the present invention is unlikely to be thinned, a member provided with the optical pressure-sensitive adhesive between the hard transparent plate and the flexible film is flexible. Even if a foreign object collides with the surface of the conductive film, it is difficult to reach a quality-related problem.

  In the said invention (invention 10), it is preferable that the said hard transparent board is a top glass of the module of a plasma display panel, and the said flexible film is a resin film (invention 11). A module of a plasma display panel having such a configuration is less likely to cause quality problems even if foreign matter collides with the surface on the top glass side.

Thirdly, the present invention provides an optical filter for a hard transparent plate, in which a pressure-sensitive adhesive layer made of an optical pressure-sensitive adhesive according to any one of the above invention claims (Inventions 1 to 11) and a flexible film are laminated. (Invention 12).
In such an optical filter for a hard transparent plate, since the adhesive layer has a storage elastic modulus and a loss elastic modulus in an appropriate range, thinning occurs even when a load is locally applied in the thickness direction of the filter. Is unlikely to occur. Therefore, such optical filters for hard transparent plates are unlikely to deteriorate in optical characteristics even if foreign matter collides with the surface on the side of the flexible film.

  The optical pressure-sensitive adhesive according to the present invention has a storage elastic modulus at 25 ° C. of 0.13 MPa or more and a loss tangent at 25 ° C. of 0.30 or less. Even when a local load is applied in the thickness direction, deformation in the thickness direction is unlikely to occur, and even if deformation occurs, the thickness of the adhesive layer will be applied if the load application is released. You can easily recover to the previous state. Therefore, the pressure-sensitive adhesive layer made of the optical pressure-sensitive adhesive according to the present invention is unlikely to be thinned, and a plasma display panel having an optical filter having this pressure-sensitive adhesive layer as a front filter is less likely to cause a color loss region on the front surface of the filter. .

It is sectional drawing which shows notionally the structure of a plasma display provided with the adhesive layer which consists of an optical adhesive which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described.
1. Optical pressure-sensitive adhesive (1) Storage elastic modulus and loss tangent An optical pressure-sensitive adhesive according to an embodiment of the present invention has a storage elastic modulus at 25 ° C. of 0.13 MPa or more and a loss tangent at 25 ° C. (hereinafter referred to as “tan δ”). Is sometimes 0.30 or less. Storage elastic modulus and loss tangent can be measured by a viscoelasticity measuring device. As an example of the viscoelasticity measuring device, there is a viscoelasticity measuring device Paar Physica MCR300 manufactured by Nippon Siebel Hegner.

  The optical pressure-sensitive adhesive according to this embodiment has a storage elastic modulus of 0.13 MPa or more and a loss tangent of 0.30 or less as a value at 25 ° C., so that it is hard and has low fluidity. Become. For this reason, when the pressure-sensitive adhesive layer comprising the optical pressure-sensitive adhesive according to the present embodiment (hereinafter referred to as “the pressure-sensitive adhesive layer”) is locally pressurized, First, deformation itself is unlikely to occur in the pressure portion and its surroundings. Furthermore, even if deformation occurs, plastic deformation is unlikely to occur. Accordingly, the deformation of the pressure-sensitive adhesive layer and its surroundings based on the pressure applied to the pressure-sensitive adhesive layer mainly consists of elastic deformation, and when the pressure is released, the state before pressurization is easily restored. can do. Therefore, it is possible to stably suppress the occurrence of thinning in the pressurized portion and the periphery thereof. From the viewpoint of more stably suppressing the thinning, the storage elastic modulus is preferably 0.14 MPa or more, and the loss tangent is preferably 0.23 or less.

  From the viewpoint of suppressing the occurrence of thinning in the present pressure-sensitive adhesive layer, the higher the storage elastic modulus at 25 ° C. of the optical pressure-sensitive adhesive according to the present embodiment, the better. For this reason, the upper limit of the storage elastic modulus is not particularly set from the above viewpoint. When the storage elastic modulus is excessively high, the upper limit may be set in consideration of the tendency that the adhesive strength of the present adhesive layer to the adherend tends to decrease. Usually, the storage elastic modulus at 25 ° C. is preferably 1 MPa or less, and more preferably 0.75 MPa or less.

  From the viewpoint of suppressing the occurrence of thinning in the present pressure-sensitive adhesive layer, the loss tangent at 25 ° C. of the optical pressure-sensitive adhesive according to this embodiment is preferably as low as possible. For this reason, the lower limit of the loss tangent is not particularly set from the above viewpoint. If the loss tangent is excessively low, the lower limit may be set in consideration of the fact that the adhesive force of the pressure-sensitive adhesive layer tends to decrease. Usually, the loss tangent at 25 ° C. is preferably 0.05 or more, and more preferably 0.10 or more.

(2) Composition The composition of the optical pressure-sensitive adhesive according to the present embodiment is not particularly limited as long as it satisfies the above-mentioned regulations regarding the storage elastic modulus and loss tangent at 25 ° C. As an example, the optical adhesive according to the present embodiment has the compositional characteristics described below. When it has such compositional characteristics, it is easy to satisfy the above-mentioned provisions concerning the storage elastic modulus and loss tangent at 25 ° C., which is preferable.

(2-1) Component Based on Polymer The optical adhesive according to this embodiment has a component based on a polymer as a main component.
The polymer that provides the main component of the optical pressure-sensitive adhesive according to this embodiment preferably contains an acrylic polymer having a weight average molecular weight of 1,500,000 or more and a glass transition temperature of -50 ° C or more.

  In the present embodiment, the “acrylic polymer” refers to one or two or more acrylic compounds selected from the group consisting of acrylic acid, methacrylic acid, and derivatives thereof (such as esters). Part of the polymer. This polymer may be a homopolymer having one of the above acrylic compounds as a monomer, or may be a copolymer having two or more of the acrylic compounds as monomers. It may be a copolymer containing one or more of an acrylic compound and other compounds, for example, an olefin such as ethylene as a monomer. A preferable aspect of the acrylic polymer according to this embodiment will be described later.

  The acrylic polymer according to this embodiment preferably has a weight average molecular weight of 1.5 million or more, and more preferably 1.6 million or more. Here, the said weight average molecular weight is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method. When the weight average molecular weight is 1,500,000 or more, it becomes easy to set the loss tangent and the storage elastic modulus in the above ranges. It becomes even easier if the weight average molecular weight is 1.6 million or more. From the viewpoint of reducing the loss tangent, the weight average molecular weight is particularly preferably within this range. The upper limit of the weight average molecular weight of the acrylic polymer is not particularly limited from the viewpoint of controlling the loss tangent and the storage elastic modulus. When the weight average molecular weight is excessively large, the viscosity of the optical pressure-sensitive adhesive is increased, and the work for forming the pressure-sensitive adhesive layer from the optical pressure-sensitive adhesive is difficult (the viscosity is difficult to decrease even if a solvent is used. In view of the fact that the solvent used for lowering tends to be less likely to volatilize), the acrylic polymer preferably has a weight average molecular weight of up to 2,200,000, more preferably 2,000,000 or less.

  The acrylic polymer according to this embodiment preferably has a glass transition temperature of −50 ° C. or higher. The glass transition temperature may be measured by any known means. As an example, it can be measured as a temperature that gives a peak of loss tangent in the temperature dependence of loss tangent of an acrylic polymer. When the glass transition temperature of the acrylic polymer according to the present embodiment is less than −50 ° C., the use temperature region of the optical pressure-sensitive adhesive containing components based on the acrylic polymer (generally 10 ° C. to 40 ° C.). There is a concern that the fluidity increases and the possibility of thinning of the pressure-sensitive adhesive layer increases. From the viewpoint of stably suppressing the occurrence of this thinning, the glass transition temperature of the acrylic polymer according to this embodiment is preferably −45 ° C. or higher, and more preferably −40 ° C. or higher. In addition, the glass transition temperature in this invention is a calculated value calculated | required from the formula of Fox.

  The acrylic polymer according to this embodiment is a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl group based on the whole monomer as a monomer constituting the acrylic polymer ( In the following description, it is also referred to as “monomer A”) in an amount of 50% by mass to 99.9% by mass, and a (meth) acrylic acid ester having a reactive functional group (in the following description, “monomer B”). It is preferable to contain 0.1 mass% or more and 20 mass% or less. The (meth) acrylic acid alkyl ester means both an acrylic acid alkyl ester and a methacrylic acid alkyl ester. The same applies to other similar terms.

  Examples of (meth) acrylic acid alkyl ester (monomer A) having 1 to 18 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) Acrylate, butyl (meth) acrylate, octyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) Examples include acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, and tetradecyl (meth) acrylate. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The specific structure of the (meth) acrylic acid ester (monomer B) having a reactive functional group is not particularly limited. Specific examples of the reactive functional group include a hydroxy group, an amino group, a carboxyl group, a glycidyl group, and an isocyanate group. Among the (meth) acrylic acid esters having a reactive functional group, specific examples of the reactive functional group having a hydroxy group or an amino group include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth). Hydroxyalkyl (meth) acrylates such as acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; and monomethylaminoethyl Examples include monoalkylaminoalkyl (meth) acrylates such as (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, and monoethylaminopropyl (meth) acrylate. That. Among these, since the obtained pressure-sensitive adhesive is not biased toward the acid side or the alkali side, coloring and the like are not easily caused by the reaction, and it has excellent bond stability, so that it has a hydroxy group as a reactive functional group ( (Meth) acrylic acid esters are preferred.

  When the content of the monomer A exceeds 99.9% by mass, the content of the monomer B is relatively lowered. For this reason, the hardening of the optical adhesive according to the present embodiment based on the inclusion of the monomer B is not sufficiently realized, and the storage elastic modulus and loss tangent of the optical adhesive satisfy the above-described range. There is a concern that it will be difficult to control. When the content of the monomer A is less than 50% by mass, it becomes difficult to control the characteristics of the optical pressure-sensitive adhesive according to the present embodiment based on the characteristics of the monomer A, and the optical There is concern that the storage elastic modulus and loss tangent of the pressure-sensitive adhesive will be difficult to satisfy the aforementioned ranges. From the viewpoint of easily controlling the storage elastic modulus and loss tangent of the optical pressure-sensitive adhesive according to the present embodiment to an appropriate range, the content of the monomer A is 80% by mass or more and 98.9% by mass or less. It is preferable to do.

  On the other hand, when the content of the monomer B is less than 0.1% by mass, the optical pressure-sensitive adhesive according to this embodiment based on the inclusion of the monomer B is not sufficiently hardened, and the optical There is concern that it may be difficult to control the storage elastic modulus and loss tangent of the adhesive for use so as to satisfy the above-described ranges. When the content of the monomer B exceeds 20% by mass, the optical adhesive is excessively hardened, and there is a concern that the function as the adhesive is reduced. From the viewpoint of sufficiently ensuring the function as a pressure-sensitive adhesive while controlling the storage elastic modulus and loss tangent of the optical pressure-sensitive adhesive according to this embodiment to an appropriate range, the content of the monomer B is 0.1 mass. % Or more and 20% by mass or less is preferable.

  In order to adjust the glass transition temperature of the acrylic polymer to the above-mentioned range, the acrylic polymer has a relatively high glass transition temperature of the homopolymer, (meth) acrylic acid, vinyl acetate, styrene, vinyl pyrrolidone, You may contain monomers other than (meth) acrylic-acid alkylesters, such as 2-phenoxyethyl (meth) acrylate, cyclohexyl acrylate, and (meth) acrylamide. Such a monomer other than the (meth) acrylic acid alkyl ester is usually contained in an amount of 0% by mass or more and 49.9% by mass or less, more preferably 1% by mass based on the whole monomer. As mentioned above, 40 mass% or less is contained.

(2-2) Crosslinked structure In the case where the acrylic polymer according to the present embodiment is formed by polymerizing the monomer A and the monomer B including the monomer B as described above, the present embodiment It is preferable to react with a crosslinking agent in the reactive functional group derived from the monomer B in the acrylic polymer to form a crosslinked structure. This formed crosslinked structure contributes to making the pressure-sensitive adhesive layer hard. The type of the crosslinking agent is not particularly limited. Specific examples of the crosslinking agent include organic peroxides such as dicumyl peroxide, compounds having an epoxy group, and isocyanate compounds. From the viewpoint of ease of reaction with the reactive functional group of the acrylic polymer, particularly the hydroxy group, a crosslinking agent comprising an isocyanate compound is preferred. Examples of the isocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, and the like. , And their biuret form, isocyanurate form, and adduct form that is a reaction product with a low molecular active hydrogen-containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The density of the cross-linked structure in the optical pressure-sensitive adhesive according to the present embodiment is the density of the cross-linking agent in the composition for preparing the optical pressure-sensitive adhesive according to the present embodiment (hereinafter also referred to as “preparation composition”). As determined by the content, this content is appropriately set according to the amount of the reactive functional group in the acrylic polymer containing the monomer B contained in the composition for preparation or a component based thereon. That's fine. Usually, in the composition for preparation, it is preferable to contain the crosslinking agent in an amount that is 0.1 to 5 equivalents relative to the amount of the reactive functional group, and an amount that is 0.2 to 3 equivalents. Is more preferable.

(2-3) Dye The optical pressure-sensitive adhesive according to this embodiment may contain a dye. As described above, this dye is contained for the purpose of imparting a near-infrared cut function, a color correction function, and the like to the optical pressure-sensitive adhesive. The specific type and content of the pigment are not limited, and should be appropriately set according to the purpose. Examples of the dye having near-infrared cutting property include a spirone compound, a phthalocyanine compound, an imonium salt compound, a thiol complex compound, a cesium tungsten oxide compound, and the like. If it is contained in an amount of about mass%, its function can be fully exhibited in many cases.

(2-4) Tackifying resin The optical pressure-sensitive adhesive according to the present embodiment preferably contains a tackifying resin. In particular, a tackifying resin having a softening point of 80 ° C. or higher is preferable. Such a tackifier resin is harder than the other components contained in the optical pressure-sensitive adhesive according to this embodiment, and thus contributes to the hardening of the optical pressure-sensitive adhesive. The softening point of the tackifying resin is more preferably 110 ° C. or higher. The softening point can be measured, for example, by the ring and ball method defined in JIS K5902.

  Although the kind of tackifying resin is not specifically limited, It is preferable to contain acid-modified rosin.

  In the present embodiment, “rosin” means a general term for rosin resins and rosin derivatives. Such rosins include non-modified rosins such as tall rosin, gum rosin, wood rosin and the like, mainly composed of resin acids such as abietic acid, neoabietic acid, parastrinic acid, pimaric acid, isopimaric acid, dehydroabietic acid, disproportionated rosin, Polymerized rosin, hydrogenated rosin, or other chemically modified rosin. The term “acid-modified” means that a carboxyl group is added to the rosin. Specific examples of the acid-modified rosin include (meth) acrylic acid, (anhydrous) maleic acid, fumaric acid, itaconic acid, (anhydrous) Examples include rosin reacted with α, β-unsaturated carboxylic acid such as citraconic acid.

  The degree of modification of the acid-modified rosin is arbitrary, but the acid value of the obtained acid-modified rosin is 200 KOHmg / g (mg amount of KOH required to neutralize 1 g of acid-modified rosin) or more. Is preferred. In this case, in addition to the fact that the tackifying resin is hard, the carboxyl group portion of the acid-modified rosin promotes the formation of a cross-linked structure by the cross-linking agent. Contribute to. Therefore, from the viewpoint of promoting the hardening of the optical pressure-sensitive adhesive, the higher the acid value of the acid-modified rosin, the better. However, if the acid value is excessively high, the acid-modified rosin is likely to be colored. The upper limit value of the content allowed for the pressure-sensitive adhesive is lowered, and the degree of the curing acceleration function by the acid-modified rosin is consequently reduced.

The content of the acid-modified rosin in the optical pressure-sensitive adhesive according to the present embodiment is preferably as high as possible from the viewpoint of making the optical pressure-sensitive adhesive according to the present embodiment hard. However, if the content is excessively high, the content is modified. The effect of coloring of the optical adhesive due to rosin is increased. When this coloring becomes a problem, the upper limit of the content of the acid-modified rosin is also set based on the allowable upper limit of coloring.
An example of a preferable range of the content of the acid-modified rosin is 1% by mass or more and 30% by mass or less, and more preferably 5% by mass or more and 20% by mass or less with respect to the entire pressure-sensitive adhesive.

(2-5) Other components The optical pressure-sensitive adhesive according to this embodiment may contain, for example, a rust inhibitor, an antistatic agent, an ultraviolet absorber, an antioxidant, and the like in addition to the above components.

  Examples of the rust preventive include benzotriazole compounds, tolyltriazole compounds, triazole compounds, phosphorus compounds, and nitrite compounds. Examples of ultraviolet absorbers include benzotriazole compounds and benzophenone compounds.

  The content of these components is not limited, but these components should be contained within a range that does not adversely affect the storage elastic modulus and loss tangent conditions that the optical adhesive according to the present embodiment should satisfy. . From this point of view, it is generally preferable that the total content of these components is about 10% by mass relative to the entire pressure-sensitive adhesive.

(3) Composition for preparation Although the preparation method of the optical adhesive which concerns on this embodiment is arbitrary, when the optical adhesive which concerns on this embodiment contains the component based on the above-mentioned acrylic polymer, and a crosslinked structure For this, it is preferable to prepare from the preparation composition described below.

  Such a composition for preparation contains at least an acrylic polymer obtained by polymerizing monomers including monomer A and monomer B, and a crosslinking agent. The acrylic polymer is obtained in a solution state by separately copolymerizing a mixture of the above monomers. The content of monomer A in the mixture of monomers is 80% by mass or more and 99.9% by mass or less based on the entire mixture, and the content of monomer B is 0.1% by mass or more and 20% by mass or less. It is below mass%. The content of the crosslinking agent in the composition for preparation is 0.1 equivalent or more and 5 equivalents or less with respect to the amount of the reactive functional group based on the monomer B in the acrylic polymer obtained by the above copolymerization. The amount of The content of the pigment is arbitrary, but if only for coloring, the amount of about 0.005% by mass relative to the acrylic polymer is sufficient. On the other hand, when the radiation shielding ability is imparted to the optical pressure-sensitive adhesive, the effect tends to be manifested from a content of about 1% by mass with respect to the acrylic polymer.

  The preparation composition may contain a tackifier in addition to the above components. Although the content is arbitrary, if an example in the case where a tackifier consists of acid-modified rosin is given, about 20 mass parts is an upper limit with respect to 100 mass parts of acrylic polymers.

  The composition for preparation further contains other components such as a rust inhibitor and a solvent as necessary. These contents are arbitrary, but usually the upper limit of the content of other components is about 10% by mass of the total components excluding the solvent of the adjustment composition, and the content of the solvent is 70% of the adjustment composition. In many cases, the upper limit is about mass%.

  The method for producing a pressure-sensitive adhesive layer (this pressure-sensitive adhesive layer) comprising the optical pressure-sensitive adhesive according to the present embodiment from the preparation composition is arbitrary. As an example, the preparation composition is applied onto a substrate using a known method such as a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, or a gravure coating method. The obtained coating layer is subjected to a treatment such as heating to carry out a crosslinking reaction with a crosslinking agent and volatilization of the solvent to obtain the present pressure-sensitive adhesive layer.

(4) Adhesive strength An adhesive sheet having a thickness of 25 μm composed of an optical adhesive according to the present embodiment is formed on a substrate composed of a 100 μm polyethylene terephthalate film to produce an adhesive sheet. When the surface of the layer side is affixed to soda lime glass, the adhesive strength of the adhesive sheet to soda lime glass is 10 N / 25 mm or less, reworkability (contamination of adherend when adhesion of adhesive is missed) It is preferable from the viewpoint that the pressure-sensitive adhesive can be removed without causing any trouble.
Here, the detail of the measuring method of the adhesive force which concerns on this embodiment is as showing to the measurement example 5 in the Example mentioned later.

  When the optical adhesive according to the present embodiment is used in a plasma display panel, it is particularly advantageous that the reworkability is high. If the adhesive of the optical adhesive to the top glass in the plasma display panel is broken, if the adhesive cannot be removed from the top glass, the top glass is contaminated. Depending on the degree of contamination, the top glass cannot be reused and the entire module may have to be discarded. Since a module including a top glass in a plasma display panel is generally expensive, the occurrence of such a situation should be avoided as much as possible. From this viewpoint, it is preferable that reworkability is high.

  The lower limit of the adhesive strength is not set from the viewpoint of reworkability, but if it is too low, it becomes difficult to function as an adhesive. Therefore, it is usually preferable to set it to 1 N / 25 mm or more.

  The optical pressure-sensitive adhesive according to this embodiment contains a component based on an acrylic polymer, and this acrylic polymer contains monomer A and monomer B as monomers as described above. In addition, it becomes easy to set the above-mentioned adhesive force in the range of 1 N / 25 mm or more and 10 N / 25 mm or less while setting the storage elastic modulus and loss tangent of the optical adhesive according to the present embodiment in the above-described ranges. If the optical pressure-sensitive adhesive according to this embodiment further contains an acid-modified rosin, it becomes easier to set these characteristics within a predetermined range.

(5) Optical properties In the present adhesive layer obtained from the optical adhesive according to this embodiment, the haze defined in JIS K7136: 2000 is preferably 10% or less, and preferably 5% or less. Further preferred. Moreover, this adhesive layer has a total light transmittance of 95% or more, more preferably 98% or more, as defined in JIS K7361-1: 1997 at a thickness of 5 μm. The optical pressure-sensitive adhesive according to the present embodiment has these optical characteristics, so that when the pressure-sensitive adhesive layer is used as a constituent element in a light-transmitting optical element such as an optical filter, an optical element with little light loss is obtained. Is realized.

2. Optical filter for hard transparent plate An optical filter for hard transparent plate according to an embodiment of the present invention is formed by laminating an adhesive layer (this adhesive layer) made of the above optical adhesive and a flexible film. Is.

  The thickness of the pressure-sensitive adhesive layer is not particularly limited. The adhesive strength and transmittance are determined according to the application, and should be determined in consideration of these factors. If an example of thickness is given, it will be the range of 5-200 micrometers.

  The flexible film is not particularly limited with respect to its constituent material, thickness, and flexibility. It should be set appropriately according to the application.

Specific examples of the material constituting the flexible film include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, and ethylene-vinyl acetate copolymer. Resin materials such as polystyrene, polycarbonate, polymethylpentene, polysulfone, polyetheretherketone, polyethersulfone, polyphenylene sulfide, polyetherimide, polyimide, fluororesin, polyamide, acrylic resin, norbornene resin, cycloolefin resin Can be mentioned. Among these, those having a high Young's modulus are preferable from the viewpoint of preventing deformation due to applied pressure, and polyester is preferable from the viewpoint of transparency and availability. The flexible film may be composed of one kind of these resin-based materials or may be composed of a plurality of kinds. As long as the required optical properties are satisfied, solid particles such as silica and titania may be dispersed or colored. In addition, an ultraviolet absorber or the like may be contained.
The thickness of the flexible film is usually in the range of about 20 μm to 250 μm, preferably 50 μm to 200 μm, and more preferably 80 μm to 160 μm. By setting it as such a range, the effect which prevents the deformation | transformation by a pressurization force further increases with a combination with an adhesive layer.

The manufacturing method of the optical filter for hard transparent plates which concerns on this embodiment is not specifically limited.
According to a specific example of the manufacturing method, a preparation composition for providing an optical pressure-sensitive adhesive according to this embodiment is prepared, and on the surface of the flexible film on which the pressure-sensitive adhesive layer is to be formed. Then, a coating layer made of the preparation composition is formed, and the coating layer is subjected to a treatment such as heating for volatilizing the solvent to obtain the pressure-sensitive adhesive layer. In order to protect the exposed surface of the present adhesive layer until use, the release surface of the release sheet is usually attached to the exposed surface of the optical filter for a hard transparent plate thus obtained.

  According to another specific example, a release sheet is first prepared, an application layer made of the above-described preparation composition is formed on the release agent surface of the release sheet, and the solvent is volatilized in the application layer. The laminated body which consists of this adhesive layer and a peeling sheet is formed by performing the process of heating for this. The surface on the side of the pressure-sensitive adhesive layer in the laminate and the surface on the side of the flexible film where the pressure-sensitive adhesive layer is to be formed are bonded, and one surface of the pressure-sensitive adhesive layer is protected by a release sheet. An optical filter for a hard transparent plate is obtained.

  According to yet another example, a laminate in which the pressure-sensitive adhesive layer is sandwiched between two release sheets is first prepared, and one release sheet of the laminate is peeled to expose the surface of the pressure-sensitive adhesive layer. The exposed surface is affixed to the surface of the flexible film where the present adhesive layer is to be formed to obtain an optical filter for a hard transparent plate in which one surface of the present adhesive layer is protected by a release sheet. .

3. Applications of optical pressure-sensitive adhesive and optical filter The optical pressure-sensitive adhesive according to this embodiment is preferably for interposing between a hard transparent plate and a flexible film. For example, when the above-described optical filter for a hard transparent plate is attached to the hard transparent plate itself or to the hard transparent plate via another layer, the optical adhesive is interposed between the hard transparent plate and the flexible film. Intervene in. A laminate in which the present pressure-sensitive adhesive layer made of the optical pressure-sensitive adhesive according to this embodiment is interposed between the hard transparent plate and the flexible film was subjected to local pressure from the flexible film side. In some cases, when the applied pressure does not cause deformation of the hard transparent plate, deformation of the pressure-sensitive adhesive layer occurs with deformation of the flexible film based on the applied pressure. Even in such a case, since the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer has the above-described characteristics relating to the storage elastic modulus and loss tangent, it is difficult for deformation to occur. When this pressure is released, the pressure-sensitive adhesive layer that has been compressed and deformed can be easily recovered to the state before pressurization, and local thinning in the pressure-sensitive adhesive layer is suppressed.

  When local thinning occurs in the pressure-sensitive adhesive layer having a dye, the amount of the dye is reduced in the thinned region, so that the color tone of the pressure-sensitive adhesive layer changes, and in some cases, color loss occurs. End up. Further, when the thickness of the pressure-sensitive adhesive layer is reduced due to the thinning, the flexible film provided on the adhesive layer is locally recessed in this region, so that a local abnormality in reflection characteristics occurs. This local abnormality may cause poor appearance on the flexible film side in the laminate. By providing this pressure-sensitive adhesive layer, the occurrence of such problems is suppressed.

  As a specific example of the hard transparent plate that is one of the members that sandwich the pressure-sensitive adhesive layer, as shown in FIG. 1, there is a top glass 1 of the module 11 of the plasma display 10. At this time, the pressure-sensitive adhesive layer 2 The flexible film that is the other of the members that sandwich the film becomes the resin film 3. This resin film is a film-like flexible member mainly composed of a resin, and is a functional film having the following performance, for example, by covering the top glass 1 of the module 11 of the plasma display 10. is there. Since the specific example of the constituent material is the same as that of the above-mentioned flexible film, description is abbreviate | omitted.

  Anti-reflective performance: Performance that prevents external light from reflecting off the screen of the plasma display 10 and reaching the observer, and because this performance is high, the visibility of the image displayed on the screen, particularly the dark color in the image Visibility of the part increases.

  Hard coat performance: Performance to prevent the screen of the plasma display 10 from being damaged. In a specific example, the hard coat performance is achieved by coating a hard material on the outer layer side of a flexible resin film. The

  Antifouling performance: performance that prevents the screen of the plasma display 10 from becoming dirty. In a specific example, the outermost layer of a flexible resin film has a water and / or oil repellent material (fluorine-based material). Etc.).

  By providing one or more of these performances, the added value of the plasma display 10 can be increased.

  The application of the optical adhesive according to the present embodiment has been described above by taking the case where the present adhesive layer is applied as a constituent member of the plasma display 10 as an example, but it can also be applied to other applications.

  For example, when the optical pressure-sensitive adhesive according to this embodiment contains the above-described substances (phthalocyanine-based compounds, imonium salt-based compounds, etc.) that shield near-infrared rays as a pigment, the pressure-sensitive adhesive layer made of this pressure-sensitive adhesive can be used. A member formed by laminating a flexible film can be attached to a window glass of an automobile or the like as an optical filter for a hard transparent plate. When this optical filter is affixed to the inside of a window glass of an automobile, even if an occupant's arm collides with the window glass and a local pressure is applied to the optical filter, a collision mark remains. It is possible to suppress appearance defects.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
(1) Preparation of composition for preparation 68.5 parts by mass of n-butyl acrylate (BA), 30 parts by mass of methyl acrylate (MA), 2-hydroxyethyl acrylate (2-hydroxyethyl acrylate, HEA) A solution of an acrylic copolymer obtained by copolymerization of 1.5 parts by mass (weight average molecular weight: 1.9 million, glass transition temperature: -39 ° C., concentration: 15% by mass) is added to 100 parts by mass of xylylene diisocyanate series. 2 parts by mass of a solution of a crosslinking agent (manufactured by Toyo Ink Manufacturing Co., Ltd., product name: BHS8515, concentration 37.5% by mass), rosin derivative having a carboxyl group (Arakawa Chemical Industries, Ltd., Pine Crystal KE-604, softening point) 130 ° C (measured by the ring and ball method)) 2.3 parts by mass, spirolone (Hodogaya Kogyo Co., Ltd., Spiron Blue GNH) 0.002 parts by mass, Imonium salt compound (Nihon Carlit Co., Ltd., CIR-1085F) 0.40 parts by mass, and methyl ethyl ketone (Methylethylketone, MEK) 30 Mass parts were added and mixed to prepare a composition for preparation.
In addition, the weight average molecular weight and glass transition temperature of an acrylic polymer are the numerical values obtained based on the measurement examples 2 and 3 mentioned later, respectively.

(2) Preparation of pressure-sensitive adhesive layer comprising optical pressure-sensitive adhesive The above-mentioned pressure-sensitive adhesive was applied to a release sheet (manufactured by Lintec, product name: SP-PET38T103-1, thickness 38 μm) so that the film thickness after drying was 25 μm. The adhesive composition was applied by a knife coating method, and the obtained coating layer was heated and dried at 100 ° C. for 1 minute to obtain a laminate in which an adhesive layer made of an optical adhesive was laminated on a release sheet. Another release sheet (manufactured by Lintec, product name: SP-PET 381031, thickness 38 μm) is bonded to the surface of the laminate on the pressure-sensitive adhesive layer side, and the pressure-sensitive adhesive layer is sandwiched between the two release sheets. Thus obtained laminate was obtained.

  The laminate was allowed to stand for 7 days in an environment of 23 ° C. and 50% RH to sufficiently advance the crosslinking reaction of the crosslinking agent contained in the optical pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer. . The laminate obtained after the aging treatment thus obtained (the pressure-sensitive adhesive layer had a thickness of 25 μm) was used as a test target.

[Example 2]
Acrylic copolymer obtained by copolymerizing 68.5 parts by mass of n-butyl acrylate (BA), 30 parts by mass of methyl acrylate (MA), and 1.5 parts by mass of 2-hydroxyethyl acrylate (HEA). Solution (weight average molecular weight: 1,600,000, glass transition temperature: -41 ° C., concentration: 23 mass%), xylylene diisocyanate-based crosslinking agent solution (product name: BHS8515, concentration) : 37.5% by mass) 4 parts by mass, rosin derivative having a carboxyl group (Arakawa Chemical Industries, Pine Crystal KE-604, softening point 130 ° C. (measured by ring and ball method)) 3.5 parts , Spirolone compound (Hodogaya Kogyo Co., Ltd., Spiron Blue GNH) 0.003 parts by mass, Imonium salt compound (Nihon Carlit Co., Ltd., CIR-1085F) 0 .61 parts by mass and 30 parts by mass of methyl ethyl ketone (MEK) were added and mixed to prepare a preparation composition.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

Example 3
Acrylic copolymer obtained by copolymerizing 63.5 parts by mass of n-butyl acrylate (BA), 35 parts by mass of methyl acrylate (MA), and 1.5 parts by mass of 2-hydroxyethyl acrylate (HEA). Solution (weight average molecular weight: 1,500,000, glass transition temperature: −37 ° C., concentration: 25 mass%), xylylene diisocyanate-based crosslinking agent solution (product name: BHS8515, concentration) : 37.5% by mass) 4 parts by mass, rosin derivative having a carboxyl group (Arakawa Chemical Industries, Pine Crystal KE-604, softening point 130 ° C. (measured by ring and ball method)) 3.5 parts , Spirolone compound (Hodogaya Kogyo Co., Ltd., Spiron Blue GNH) 0.003 parts by mass, Imonium salt compound (Nihon Carlit Co., Ltd., CIR-1085F) 0 .67 parts by mass and 30 parts by mass of methyl ethyl ketone (MEK) were added and mixed to prepare a preparation composition.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

Example 4
Acrylic copolymer solution obtained by copolymerizing 67 parts by mass of n-butyl acrylate (BA), 30 parts by mass of methyl acrylate (MA), and 3.0 parts by mass of 2-hydroxyethyl acrylate (HEA). (Weight average molecular weight: 1.6 million, glass transition temperature: -39 ° C., concentration: 23% by mass) 100 parts by mass of a solution of xylylene diisocyanate-based crosslinking agent (product name: BHS8515, concentration: 37 .5 mass%) 3 parts by mass, rosin derivative having a carboxyl group (Arakawa Chemical Industries, Pine Crystal KE-604, softening point 130 ° C. (measured by ring and ball method)) 3.5 parts, spirone System compound (Hodogaya Kogyo Co., Ltd., Spiron Blue GNH) 0.003 parts by mass, imonium salt compound (Nihon Carlit Co., Ltd., CIR-1085F) 0.6 1 part by mass and 30 parts by mass of methyl ethyl ketone (MEK) were added and mixed to prepare a preparation composition.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

Example 5
An acrylic copolymer obtained by copolymerizing 48.5 parts by mass of n-butyl acrylate (BA), 50 parts by mass of ethyl acrylate (EA) and 1.5 parts by mass of 2-hydroxyethyl acrylate (HEA). To 100 parts by mass of a polymer solution (weight average molecular weight: 2 million, glass transition temperature: −40 ° C., concentration: 16% by mass), a solution of xylylene diisocyanate-based crosslinking agent (product name: BHS8515, manufactured by Toyo Ink Co., Ltd.) , Concentration: 37.5% by mass) 2.3 parts by mass, rosin derivative having a carboxyl group (Arakawa Chemical Industries, Pine Crystal KE-604, softening point 130 ° C. (measured by ring and ball method)) 2.5 parts, spirone compound (Hodogaya Kogyo Co., Ltd., Spiron Blue GNH) 0.002 parts by mass, imonium salt compound (Nippon Carlit) Co., Ltd., CIR-1085F) 0.43 parts by mass and methyl ethyl ketone (MEK) 30 parts by mass were added and mixed to prepare a preparation composition.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

Example 6
Acrylic copolymer obtained by copolymerizing 68.5 parts by mass of n-butyl acrylate (BA), 30 parts by mass of methyl acrylate (MA), and 1.5 parts by mass of 2-hydroxyethyl acrylate (HEA). Solution (weight average molecular weight: 1,900,000, glass transition temperature: -39 ° C., concentration: 15% by mass) in 100 parts by mass of a solution of xylylene diisocyanate crosslinking agent (product name: BHS8515, concentration by Toyo Ink Mfg. Co., Ltd.) : 37.5% by mass) 2 parts by mass, rosin derivative having a carboxyl group (Arakawa Chemical Industries, Ltd., Pine Crystal KE-604), spirone compound (Hodogaya Kogyo Co., Ltd., spiro) Blue GNH) 0.002 parts by mass, imonium salt compound (manufactured by Nippon Carlit Co., Ltd., CIR-1085F) 0.40 parts by mass, and methyl ethyl ketone (MEK) ) 30 parts by mass were added and mixed to prepare a composition for preparation.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

Example 7
About the laminated body of Example 1, the flexible film in the measurement examples 4 and 5 was changed, and the optical film was produced.

[Comparative Example 1]
A solution of an acrylic copolymer obtained by copolymerizing 98.5 parts by mass of n-butyl acrylate (BA) and 1.5 parts by mass of 2-hydroxyethyl acrylate (HEA) (weight average molecular weight: 2,200,000, Glass transition temperature: -54 ° C., concentration: 16% by mass) 100 parts by mass of xylylene diisocyanate crosslinking agent solution (product name: BHS8515, concentration: 37.5% by mass) 0.6 Part by mass, rosin derivative having carboxyl group (Arakawa Chemical Industries, Pine Crystal KE-604, softening point 130 ° C. (measured by ring and ball method)), spirone compound (Hodogaya Industry) Co., Ltd., Spiron Blue GNH) 0.002 parts by mass, imonium salt compound (Nihon Carlit Co., Ltd., CIR-1085F) 0.43 parts by mass, and methylethyl 30 parts by mass of ketone (MEK) was added and mixed to prepare a preparation composition.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

[Comparative Example 2]
68 parts by mass of n-butyl acrylate (BA), 30 parts by mass of methyl acrylate (MA), 1.5 parts by mass of 2-hydroxyethyl acrylate (HEA), 0.5 parts by mass of methacrylamide (MAAm) To 100 parts by mass of an acrylic copolymer solution (weight average molecular weight: 800,000, glass transition temperature: −35 ° C., concentration: 30 mass%) obtained by copolymerization, a solution of xylylene diisocyanate crosslinking agent (Toyo Manufactured by Ink Manufacturing Co., Ltd., product name: BHS8515, concentration: 37.5% by mass) 0.9 parts by mass, spirone compound (manufactured by Hodogaya Kogyo Co., Ltd., spiron blue GNH) 0.002 parts by mass, imonium salt compound (Nippon Carlit Co., Ltd., CIR-1085F) 0.40 parts by mass, and methyl ethyl ketone (MEK) 30 parts by mass, these Were mixed to prepare a preparation composition.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

[Comparative Example 3]
Acrylic copolymer obtained by copolymerizing 48.5 parts by mass of n-butyl acrylate (BA), 50 parts by mass of ethyl acrylate (EA), and 1.5 parts by mass of 2-hydroxyethyl acrylate (HEA). Solution (weight average molecular weight: 2 million, glass transition temperature: −40 ° C., concentration: 18% by mass), xylylene diisocyanate-based crosslinking agent solution (product name: BHS8515, concentration) : 37.5% by mass) 3.4 parts by mass, a rosin derivative having a carboxyl group (Arakawa Chemical Industries, Pine Crystal KE-604, softening point 130 ° C. (measured by ring and ball method)) 7 parts, spirone compound (Hodogaya Kogyo Co., Ltd., Spiron Blue GNH) 0.002 parts by mass, imonium salt compound (Nippon Carlit Co., Ltd., CIR-1085F) ) 0.48 parts by mass and 30 parts by mass of methyl ethyl ketone (MEK) were added and mixed to prepare a preparation composition.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

[Comparative Example 4]
N-butyl acrylate 68 parts by mass, ethyl acrylate 20 parts by mass, acryloylmorpholine (ACMO) 10 parts by mass, 2-hydroxyethyl acrylate (HEA) 1.5 parts by mass, methacrylamide (MAAm) 0.5 To 100 parts by mass of an acrylic copolymer solution obtained by copolymerizing parts by mass (weight average molecular weight: 800,000, glass transition temperature: -35 ° C., concentration: 30% by mass), the xylylene diisocyanate crosslinking agent 2.0 parts by mass of solution (manufactured by Toyo Ink Co., Ltd., product name: BHS8515, concentration: 37.5% by mass), 0.004 parts by mass of spirone compound (spiron blue GNH, manufactured by Hodogaya Kogyo Co., Ltd.), imonium 0.80 part by mass of a salt compound (Nippon Carlit Co., Ltd., CIR-1085F), and methyl ethyl ketone It was added down (MEK) 30 parts by weight, and mixing them to prepare a precursor composition.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

[Comparative Example 5]
Acrylic obtained by copolymerizing 77 parts by mass of 2-ethylhexyl acrylate (2-ethylhexylacrylate, 2EHA), 20 parts by mass of methyl methacrylate (MMA) and 3.0 parts by mass of 2-hydroxyethyl acrylate (HEA). 100 parts by mass of a copolymer solution (weight average molecular weight: 700,000, glass transition temperature: −60 ° C., concentration: 40% by mass), a solution of xylylene diisocyanate crosslinking agent (product name, manufactured by Toyo Ink Manufacturing Co., Ltd.) : 1.5 parts by mass of BHS8515, concentration: 37.5% by mass, rosin derivative having carboxyl group (Arakawa Chemical Industries, Pine Crystal KE-604, softening point 130 ° C. (measured by ring and ball method) )) 1.4 parts, spirone compound (Hodogaya Kogyo Co., Ltd., Spirombull) GNH) 0.005 parts by mass, Imonium salt compound (Nippon Carlit Co., Ltd., CIR-1085F) 1.07 parts by mass, and methyl ethyl ketone (MEK) 30 parts by mass are added and mixed for preparation. A composition was prepared.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

[Comparative Example 6]
Acrylic copolymer solution obtained by copolymerizing 72 parts by mass of 2-ethylhexyl acrylate (2EHA), 25 parts by mass of methyl methacrylate (MMA) and 3.0 parts by mass of 2-hydroxyethyl acrylate (HEA) (Weight average molecular weight: 700,000, glass transition temperature: -55 ° C., concentration: 40% by mass) 100 parts by mass of a solution of xylylene diisocyanate-based crosslinking agent (product name: BHS8515, concentration: 37 by Toyo Ink Mfg. Co., Ltd.) .5 mass%) 2.1 parts by mass, rosin derivative having a carboxyl group (Arakawa Chemical Industries, Pine Crystal KE-604, softening point 130 ° C. (measured by ring and ball method)) 1.5 parts , Spiron compound (Hodogaya Kogyo Co., Ltd., Spiron Blue GNH) 0.005 parts by mass, Imonium salt compound (Nippon Carlit Co., Ltd., CIR) 1085F) 1.07 parts by weight, and methyl ethyl ketone (MEK) was added 30 parts by weight, and mixing them to prepare a precursor composition.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

[Comparative Example 7]
Acrylic copolymer obtained by copolymerizing 68.5 parts by mass of n-butyl acrylate (BA), 30 parts by mass of methyl acrylate (MA), and 1.5 parts by mass of 2-hydroxyethyl acrylate (HEA). Solution (weight average molecular weight: 1,900,000, glass transition temperature: -39 ° C., concentration: 15% by mass) in 100 parts by mass of a solution of xylylene diisocyanate crosslinking agent (product name: BHS8515, concentration by Toyo Ink Mfg. Co., Ltd.) : 37.5% by mass) 2 parts by mass, spirone compound (manufactured by Hodogaya Kogyo Co., Ltd., Spiron Blue GNH) 0.002 parts by mass, imonium salt compound (manufactured by Nippon Carlit Co., Ltd., CIR-1085F) 0 40 parts by mass and 30 parts by mass of methyl ethyl ketone (MEK) were added and mixed to prepare a preparation composition.
Using the obtained preparation composition, the same steps as in Example 1 were performed, and an adhesive layer (thickness 25 μm) was sandwiched between two release sheets, and the laminate after aging treatment was obtained. Obtained as a test subject.

[Measurement Example 1] Measurement of Viscoelasticity One release sheet in a laminate as a test object according to Examples and Comparative Examples was peeled off, and the remaining laminate was folded in half so that the pressure-sensitive adhesive layer contacted. The release sheet was half peeled from this laminate to obtain a laminate in which an adhesive layer having a double thickness (50 μm) was provided on the release sheet. About this laminated body, bending which an adhesive layer contact | abuts, and peeling of a half release sheet were repeated, and the laminated body by which the adhesive layer about 1 mm thick was laminated | stacked on the release sheet was obtained.
With respect to the adhesive layer having a thickness of about 1 mm formed by peeling the release sheet from the laminate, the storage elastic modulus and loss tangent at a temperature of 25 ° C. are measured using a viscoelasticity measuring device (Paar Physica MCR300 manufactured by Nippon Shibel Hegner) tan δ) was determined. The measurement results are shown in Table 1.

[Measurement Example 2] Weight average molecular weight Gel permeation chromatography (GPC) method in terms of polystyrene (apparatus: HLC-8220GPC manufactured by Tosoh Corporation, solvent: THF, liquid feed rate: 0.6 mL / min, column: TSK-gelGMHXL ), The weight average molecular weight of each acrylic polymer was measured. The measurement results are as described above.

[Measurement Example 3] Evaluation of presence or absence of color loss after load test One release sheet is peeled off from the laminates to be tested according to the examples and comparative examples, and the pressure-sensitive adhesive layer side surface of the laminate is flexible. An adhesive film (PET100A4300, manufactured by Toyobo Co., Ltd., thickness 100 μm) was attached, and a 50 mm × 50 mm test piece was cut out from the obtained laminate (optical filter with a release sheet). The release sheet of this test piece was peeled off to obtain an adhesive sheet (optical filter) composed of a flexible film and an optical adhesive. The surface on the pressure-sensitive adhesive layer side of the obtained pressure-sensitive adhesive sheet is attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.) using a 2 kg rubber roller, and a flexible film, pressure-sensitive adhesive layer and soda lime glass are attached. Obtained a laminated body for testing which was laminated in this order. Only Example 7 was attached to a flexible film (Toyobo Co., Ltd., PET100A4300, thickness 75 μm).

  Simulating the condition that a relatively strong applied pressure is applied for a short time, the maximum surface pressure of Hertz is from the flexible film side of the above test laminate in an atmosphere of a standard state of 23 ° C. and 50% RH. A load of 63 MPa was applied for 1 minute. Hereinafter, this test is referred to as “heavy load test”. Further, by imitating a condition in which a relatively weak pressing force is applied for a long time, a load at which the maximum surface pressure of Hertz is 40 MPa in the above atmosphere is applied for 4 minutes from the flexible film side of the test laminate. Applied. Hereinafter, this test is referred to as a “light load test”. In calculating the maximum surface pressure of these hertz, the Young's modulus of the optical filter was 2000 MPa.

In both the heavy load test and the light load test, the application of the load was canceled, and the portion to which the load was applied was visually observed from the flexible film side. This test was repeated 5 times for each test laminate, and when no change was observed in the color tone of the part, it was judged that the test was particularly good ("◎" in Table 1), and the color tone was changed. The case was determined to be good (“◯” in Table 1) when it was once or twice, and judged to be defective (“×” in Table 1) when the color tone changed three or more times.
The measurement results are shown in Table 1.

[Measurement Example 4] Measurement of adhesive strength and evaluation of presence or absence of adhesive residue The adhesive strength to glass (soda lime glass) was measured according to JIS 0237: 2009.
One release sheet is peeled off from the laminates to be tested according to Examples and Comparative Examples, and the adhesive layer side surface of the laminate is applied to a flexible film (Toyobo Co., Ltd., PET100A4300, thickness 100 μm). A test piece of 25 mm × 250 mm was cut out from the obtained laminate (optical filter with release sheet). The release sheet of this test piece was peeled off to obtain an adhesive sheet (optical filter) composed of a flexible film and an optical adhesive. The surface on the pressure-sensitive adhesive layer side of the obtained pressure-sensitive adhesive sheet is attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.) using a 2 kg rubber roller, and a flexible film, pressure-sensitive adhesive layer and soda lime glass are attached. Obtained a laminated body for testing which was laminated in this order. Only Example 7 was attached to a flexible film (Toyobo Co., Ltd., PET100A4300, thickness 75 μm).

The obtained test laminate was allowed to stand (seasoning) in a standard condition atmosphere at 23 ° C. and 50% RH immediately after production.
Next, using a tensile tester (Orientec Co., Ltd., Tensilon), the adhesive sheet portion (optical filter) in the test laminate after standing was peeled off at a peeling speed of 300 mm / min and a peeling angle of 180 °. The peel load measured at this time was defined as the adhesive strength (unit: N / 25 mm).

Moreover, the soda-lime glass after peeling was observed visually, and it was confirmed whether the adhesive derived from an adhesive layer remained (there is adhesive residue). A case where no adhesive residue was observed was judged as good (“◯” in Table 1), and a case where adhesive residue was observed was judged as poor (“×” in Table 1).
The measurement results are shown in Table 1.

  As is clear from Table 1, the optical adhesives obtained in the examples that satisfy the requirements of the present invention gave good or particularly good results in both the heavy load test and the light load test. .

  The pressure-sensitive adhesive layer comprising the optical pressure-sensitive adhesive of the present invention is suitably used as a pressure-sensitive adhesive layer for fixing optical components such as a dye-containing pressure-sensitive adhesive layer for fixing a front filter on the top glass of a module in a plasma display panel. Can be used.

DESCRIPTION OF SYMBOLS 10 ... Plasma display 11 ... Plasma display module 1 ... Top glass 2 of plasma display module ... This adhesive layer 3 ... Resin film

Claims (12)

  An optical pressure-sensitive adhesive containing a dye, wherein a loss tangent at 25 ° C. is 0.30 or less, and a storage elastic modulus at 25 ° C. is 0.13 MPa or more.   The optical pressure-sensitive adhesive according to claim 1, comprising a component based on an acrylic polymer having a weight average molecular weight of 1,500,000 or more and a glass transition temperature of -50 ° C or more.   The optical pressure-sensitive adhesive according to claim 2, further comprising a tackifying resin.   An optical pressure-sensitive adhesive comprising a component based on an acrylic polymer having a weight average molecular weight of 1,500,000 or more and a glass transition temperature of -50 ° C or more, and a tackifying resin.   The acrylic polymer is a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl group as a monomer constituting the acrylic polymer, and 50 mass% or more and 99.9 mass% or less, and (Meth) acrylic acid ester having a reactive functional group is contained in an amount of 0.1% by mass to 10% by mass, and the acrylic polymer reacts with a crosslinking agent in the reactive functional group to form a crosslinked structure. Item 5. The optical pressure-sensitive adhesive according to any one of Items 2 to 4.   The optical pressure-sensitive adhesive according to claim 5, wherein the crosslinking agent contains an isocyanate-based crosslinking agent.   The optical pressure-sensitive adhesive according to any one of claims 3 to 6, wherein the tackifying resin contains an acid-modified rosin.   The optical pressure-sensitive adhesive according to claim 7, wherein the acid value of the acid-modified rosin is 200 KOHmg / g or more.   A pressure-sensitive adhesive layer having a thickness of 25 μm made of the optical pressure-sensitive adhesive is formed on a substrate made of a 100 μm polyethylene terephthalate film to produce a pressure-sensitive adhesive sheet, and the surface of the pressure-sensitive adhesive sheet on the pressure-sensitive adhesive layer side is soda lime glass. The optical pressure-sensitive adhesive according to any one of claims 1 to 8, wherein the pressure-sensitive adhesive sheet has an adhesive strength to the soda-lime glass of 10 N / 25 mm or less.   The optical pressure-sensitive adhesive according to any one of claims 1 to 9, which is for interposing between a hard transparent plate and a flexible film.   The optical adhesive according to claim 10, wherein the hard transparent plate is a top glass of a module of a plasma display panel, and the flexible film is a resin film.   An optical filter for a hard transparent plate, wherein a pressure-sensitive adhesive layer made of the optical pressure-sensitive adhesive according to any one of claims 1 to 11 and a flexible film are laminated.

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