KR20210145102A - Adhesive sheet and method of producing the same - Google Patents

Abstract

Provided are an adhesive sheet in which occurrence of uneven patterns on a substrate is suppressed and an adhesive sheet manufacturing method not requiring wet lamination and suppressing occurrence of uneven patterns on a substrate. According to the present invention, the adhesive sheet comprises: a first plastic film substrate (11A) having a thickness of 10 to 200 μm; a second plastic film substrate (11B) having a thickness of 10 to 200 μm; and an adhesive layer (12) having a film thickness of 100 to 500 μm and sandwiched between the first plastic film substrate (11A) and the second plastic film substrate (11B). According to the present invention, when a projector emitting white light, a sample formed by cutting the adhesive sheet (1) to form a square of 1 m in length and width, and a screen are sequentially arranged at intervals of 0.9 m and 0.3 m, one or less substrate uneven pattern is projected on the screen as a shade having a length of 50 cm or more and a width of 3 mm.

Description

The manufacturing method of an adhesive sheet and an adhesive sheet TECHNICAL FIELD

The present invention relates to a pressure-sensitive adhesive sheet and a method for manufacturing the pressure-sensitive adhesive sheet, and more particularly, to a pressure-sensitive adhesive sheet in which the occurrence of a pattern (hereinafter referred to as "concave-convex pattern") in which the cross-section is uneven on a substrate is suppressed, and a method for manufacturing such a pressure-sensitive adhesive sheet is about

The active energy ray-curable pressure-sensitive adhesive has an active energy ray-curable resin material having a reactive functional group and a photopolymerization initiator as main components, and forms a crosslinked structure by irradiating a predetermined amount with ultraviolet rays or electron beams.

Since the active energy ray-curable resin material has a viscosity of tens of thousands of mPa·s at room temperature, in order to coat, it is heated until fluidity is expressed, adjusted to a viscosity suitable for processing, and then coated, or a resin material A method of lowering the viscosity of the coating solution by adding a solvent or a low molecular weight substance such as an acrylic acid ester monomer to it and improving the workability at room temperature is used.

In particular, in the UV-curable adhesive of the type in which a low-molecular weight substance is added without adding a solvent (hereinafter referred to as "solvent-free UV-curable adhesive"), the low molecular weight substance reacts with UV irradiation to form a covalent bond with the resin material, It has various advantages not found in solvent dilution type adhesives, such as thick film coating possible, no drying process, and low environmental impact because it does not contain solvents. The solvent-free UV-curable pressure-sensitive adhesive is often used for manufacturing a thick-film pressure-sensitive adhesive sheet with a thick pressure-sensitive adhesive layer by making use of the above advantages.

In general, UV-curable pressure-sensitive adhesives employing a radical polymerization photoinitiator cause curing failure in the presence of oxygen.

In a 1st adhesive sheet processing method, after apply|coating the coating liquid of an ultraviolet curable adhesive to a coating base material, ultraviolet-ray is irradiated in nitrogen atmosphere, the ultraviolet curing reaction is completed, the adhesive layer is formed, and the bonding base material is laminated to the adhesive layer. In the second pressure-sensitive adhesive sheet processing method, after applying a coating liquid of an ultraviolet curable pressure-sensitive adhesive to a coating substrate, the bonding substrate is laminated (wet lamination) to a liquid coating film, and UV-curing reaction is performed by irradiating ultraviolet rays in a state in which contact with oxygen is cut off. is completed to form an adhesive layer (Patent Document 1).

Publication No. 2006-306081

However, in the first pressure-sensitive adhesive sheet processing method, it is necessary to continuously flow a large amount of nitrogen gas during processing, and although it is necessary to introduce a facility for continuously introducing nitrogen gas, the loss of nitrogen gas is large, so the product cost is increased There is a growing problem. In addition, when the reaction proceeds in the UV irradiation process, the pressure-sensitive adhesive cures and shrinks, and uneven patterns are generated on the coating substrate, which may damage the appearance of the product. In particular, in the case of forming the pressure-sensitive adhesive layer having a film thickness, the occurrence of uneven patterns on the substrate in the ultraviolet irradiation step is a serious problem.

In addition, in the second pressure-sensitive adhesive sheet processing method, if the lamination pressure during wet lamination is high, the coating film is crushed and the film thickness of the pressure-sensitive adhesive layer is not constant, or the coating solution leaches to contaminate the inside of the process. On the other hand, when lamination pressure is low, air will be disperse|distributed at the time of lamination, and it will become a cause of the lack of hardening at the time of ultraviolet irradiation. Therefore, in the said 2nd adhesive sheet processing method, it is necessary to manage the lamination pressure at the time of wet lamination appropriately, and effort is required for the control.

The present invention has been made in view of this situation, and it does not require a pressure-sensitive adhesive sheet in which the occurrence of uneven patterns on a substrate and a wet lamination is not required, and a method for producing a pressure-sensitive adhesive sheet capable of suppressing the occurrence of uneven patterns on such a substrate. intended to provide Furthermore, it aims at improving the stability of the optical characteristic in the optical laminated body which has a film-thick adhesive layer.

In order to achieve the above object, first, the present invention provides a first plastic film substrate having a thickness of 10-200 μm, a second plastic film substrate having a thickness of 10-200 μm, the first plastic film substrate and the second plastic film substrate. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a film thickness of 100 to 500 μm sandwiched therebetween, a projector emitting white light, a sample in which the pressure-sensitive adhesive sheet is cut out so as to have a square of 1 m in length and width, and a screen, each 0.9 m in that order; Provided is an adhesive sheet characterized in that, when arranged at an interval of 0.3 m, there is at least one substrate uneven pattern projected on the screen as a shadow of 50 cm or more in length and 3 mm or more in width (Invention 1).

In the pressure-sensitive adhesive sheet according to the invention (Invention 1), the occurrence of uneven patterns in the first plastic film substrate and the second plastic film substrate is suppressed. When such a pressure-sensitive adhesive sheet is used, an optical laminate having a film-thick pressure-sensitive adhesive layer and excellent stability in optical properties can be produced.

In the said invention (invention 1), it is preferable that the dispersion|variation in the film thickness of the said adhesive layer is 5 % or less (invention 2).

In the above inventions (Inventions 1 and 2), the pressure-sensitive adhesive layer is preferably a pressure-sensitive adhesive layer formed by coating and curing an ultraviolet curable pressure-sensitive adhesive composition (Invention 3).

Second, the present invention provides a method for manufacturing the pressure-sensitive adhesive sheet (invention 3), comprising the steps of: coating one side of the first plastic film substrate with the pressure-sensitive adhesive composition; A pre-curing step of pre-curing the pressure-sensitive adhesive composition, a step of laminating the second plastic film substrate on the coating film of the pre-cured pressure-sensitive adhesive composition, and the first plastic film substrate or the second plastic film substrate, The coating film of the pre-cured adhesive composition is irradiated with ultraviolet rays, the adhesive composition is main-cured to form a pressure-sensitive adhesive layer, and a main curing step is provided. To provide a method for manufacturing a pressure-sensitive adhesive sheet, characterized in that greater than the amount of ultraviolet light irradiated in (Invention 4).

According to the above invention (Invention 4), the film thickness of the pressure-sensitive adhesive layer can be made uniform without requiring wet lamination, and the occurrence of uneven patterns in the first plastic film substrate and the second plastic film substrate can be suppressed. can

In the above invention (Invention 4), the illuminance of the ultraviolet ray irradiated in the pre-curing step is 1 to 100 mW/cm ² , the amount of light is 10 to 100 mJ/cm ² , and the illuminance of the ultraviolet ray irradiated in the main curing process is 1 to 1000 mW/cm ² , and the amount of light is preferably more than 100 ^{mJ/cm 2 (Invention 5).}

In the said invention (invention 4, 5), it is preferable that the said adhesive composition does not contain a solvent (invention 6).

In the above inventions (Inventions 4 to 6), the pressure-sensitive adhesive composition is a prepolymer of (meth)acrylic acid ester having a radically polymerizable unsaturated double bond group and having a weight average molecular weight of 20,000 or more and/or a urethane (meth) having a weight average molecular weight of 20,000 or more ) It is preferable to contain the oligomer of an acrylate, at least 1 type of (meth)acrylic acid ester monomer, and a photoinitiator (invention 7).

ADVANTAGE OF THE INVENTION According to this invention, the adhesive sheet by which generation|occurrence|production of the uneven|corrugated pattern in a base material was suppressed can be provided. Moreover, according to the manufacturing method of the adhesive sheet which concerns on this invention, while not requiring a wet lamination, the film thickness of an adhesive layer can be made uniform, and generation|occurrence|production of the uneven pattern in a base material can be suppressed. Furthermore, by the said adhesive sheet, the stability of the optical characteristic in the optical laminated body which has a film-thick adhesive layer can be improved.

1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

[adhesive sheet]

As shown in FIG. 1 , the pressure-sensitive adhesive sheet 1 according to the present embodiment includes a first plastic film substrate 11A, a second plastic film substrate 11B, a first plastic film substrate 11A, and a second plastic film substrate 11A. It is made by providing the pressure-sensitive adhesive layer 12 sandwiched between the two plastic film substrates 11B.

The pressure-sensitive adhesive sheet 1 has 1 or less, preferably 0, substrate uneven patterns defined below.

Substrate uneven pattern: The adhesive sheet 1 cut out in a square of 1 m in length and width each is taken as a sample. When a projector emitting white light, the sample, and the screen are arranged at intervals of 0.9 m and 0.3 m, respectively, in that order (the sample and the screen are parallel), they are projected onto the screen as shades of 50 cm or more in length and 3 mm or more in width The concavo-convex pattern in the first plastic film substrate 11A or the second plastic film substrate 11B to be used is referred to as the substrate concavo-convex pattern. On the other hand, as long as the projector can observe the presence or absence of the shadow, it is not limited in any way, but, for example, a projector having an LED light source of 500 lumens can be used.

The thickness of the 1st plastic film base material 11A and the 2nd plastic film base material 11B in the said adhesive sheet 1 is 10-200 micrometers, respectively, and the film thickness of the adhesive layer 12 is 100-500 micrometers.

In general, curing shrinkage tends to occur in the pressure-sensitive adhesive layer having a film thickness of 100 μm or more, and in a plastic film substrate having a thickness of 200 μm or less, there is a problem that irregularities can be easily generated due to curing shrinkage of the pressure-sensitive adhesive layer. However, in the pressure-sensitive adhesive sheet 1 according to the present embodiment, although the thicknesses of the first plastic film substrate 11A, the second plastic film substrate 11B, and the pressure-sensitive adhesive layer 12 are as described above, the substrate The number of uneven patterns is one or less, and the occurrence of uneven patterns in the first plastic film substrate 11A and the second plastic film substrate 11B is suppressed. Such an adhesive sheet 1 is excellent in an external appearance and is suitable also for optical uses, such as a display and a touch panel.

The first plastic film substrate 11A in this embodiment is a coating substrate to be coated with an adhesive (adhesive composition), and the second plastic film substrate 11B in this embodiment is a coated adhesive (adhesive composition) of It is a bonding base material laminated to a coating film.

It does not specifically limit as the 1st plastic film base material 11A and the 2nd plastic film base material 11B, Various plastic film materials can be used. The first plastic film substrate 11A and the second plastic film substrate 11B may be, for example, optical members assembled in a display device or the like, or may be peeling films that are peeled off during use.

As a material of the 1st plastic film base material 11A and the 2nd plastic film base material 11B, For example, polyester films, such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, a polyurethane film, a polyethylene film , polypropylene film, cellulose film such as triacetyl cellulose (TAC), polyvinyl chloride film, polyethylene vinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, acrylic resin film , norbornene-based resin films, plastic films such as cycloolefin resin (COP) films, laminates of two or more types of these plastic films, release agent layer, hard coat layer, anti-glare layer, reflective layer, transparent on one or both sides of these plastic films The thing provided with functional layers, such as an electrically conductive film and a colored layer, etc. are mentioned.

Moreover, it is preferable that at least one of the 1st plastic film base material 11A and the 2nd plastic film base material 11B is an optical member. Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a retardation plate (retardation film), a viewing angle compensation film, a luminance enhancing film, a contrast enhancing film, a liquid crystal polymer film, a diffusion film, a transflective film, etc. have.

Moreover, it is also preferable that at least one of the 1st plastic film base material 11A and the 2nd plastic film base material 11B is a peeling film. The release film in this specification means that the release agent layer is provided in at least one surface of the above-mentioned various plastic films, for example. The release agent layer is composed of, for example, release agents such as alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax.

Here, when both the first plastic film base material 11A and the second plastic film base material 11B are used as release films, a predetermined difference in the peel force of the two release films from the viewpoint of preventing peeling failure is It is preferable to make one peeling film into a medium peeling type peeling film, and to use the other peeling film as a light peeling type peeling film so that it may generate|occur|produce. In addition, peeling force can be suitably adjusted by the composition of a release agent layer, crosslinking degree, film thickness, etc.

In addition, when manufacturing the adhesive sheet 1 by the method using ultraviolet irradiation as mentioned later, at least one of the 1st plastic film base material 11A and the 2nd plastic film base material 11B is transparent (ultraviolet-ray transmittance). ) needs to be Here, ultraviolet transmittance means the ability to transmit ultraviolet rays of a wavelength required for ultraviolet curing.

The thickness of the 1st plastic film base material 11A and the 2nd plastic film base material 11B is 10-200 micrometers, respectively, Preferably it is 20-175 micrometers, Especially preferably, it is 25-150 micrometers, Most preferably, it is 30- 90 μm. When the thickness of the 1st plastic film base material 11A and the 2nd plastic film base material 11B is less than 10 micrometers, it will become difficult to make said base material uneven|corrugated pattern into one or less. In addition, the first plastic film substrate 11A and the second plastic film substrate 11B are required to be thinned from the viewpoint of cost reduction and optical properties improvement, and when the thickness exceeds 200 μm, such an effect is expected. can't On the other hand, when the thickness of the first plastic film substrate 11A and the second plastic film substrate 11B exceeds 200 μm, no uneven patterns are generated on those substrates, and it is easy to set the number of uneven patterns on the substrate to one or less in the first place. will do

The material and thickness of the 1st plastic film base material 11A and the 2nd plastic film base material 11B may be the same, respectively, and may differ.

The pressure-sensitive adhesive layer 12 bonds the first plastic film substrate 11A and the second plastic film substrate 11B together. It is preferable that the adhesive layer 12 coats and hardens|cures an ultraviolet curable adhesive composition. By adjusting the composition of the ultraviolet curable adhesive composition, it becomes possible to make the said base material uneven|corrugated pattern into one or less. The detailed description of this ultraviolet curable adhesive composition is mentioned later.

The film thickness of the adhesive layer 12 is 100-500 micrometers, Preferably it is 150-400 micrometers, Especially preferably, it is 175-300 micrometers. When the film thickness of the adhesive layer 12 is less than 100 micrometers, characteristics requested|required of the adhesive of a film thickness, such as step|step difference followability|trackability and shock absorption property, cannot fully be exhibited. On the other hand, when the film thickness is less than 100 μm, the degree of curing shrinkage of the pressure-sensitive adhesive layer 12 is small, so that the uneven pattern does not occur on the first plastic film substrate 11A or the second plastic film substrate 11B, and the substrate unevenness is not generated. It becomes easy to set the pattern to one or less. On the other hand, when the film thickness of the adhesive layer 12 exceeds 500 micrometers, the degree of cure shrinkage of the adhesive layer 12 becomes large too much, and it becomes difficult to make the said base material uneven|corrugated pattern into one or less.

It is preferable that the film thickness dispersion|variation of the adhesive layer 12 is 5 % or less, It is especially preferable that it is 4 % or less, Furthermore, it is preferable that it is 3 % or less. When the film thickness variation of the pressure-sensitive adhesive layer 12 exceeds 5%, the smoothness of the pressure-sensitive adhesive layer 12 is lost, for example, the adhesiveness when the pressure-sensitive adhesive sheet 1 is used for a touch panel product deteriorates, and the product There is a risk of lowering the yield. In addition, there is a possibility that the touch sensor unit of the touch panel may malfunction.

In addition, the film thickness variation (%) of the adhesive layer 12 is measured as follows. The pressure-sensitive adhesive sheet 1 is cut out into a square of 1 m in length and width, and a sheet (length 20 cm x width 50 cm) obtained by dividing this into 10 equal parts is prepared. The adhesive layer 12 which peeled the 1st plastic film base material 11A and the 2nd plastic film base material 11B from this sheet|seat is used as a sample, and each sample measures the film thickness with respect to one arbitrary point. In other words, the film thickness of 10 points is measured at random about the square adhesive sheet of 1 m in length and width each. Then, the average film thickness, the maximum film thickness, and the minimum film thickness are derived, and any larger value calculated by the following formulas (a) and (b) is defined as the film thickness variation (%) of the pressure-sensitive adhesive layer (12). do.

{(maximum film thickness-average film thickness)/ (average film thickness)}×100… (a)

{(average film thickness - minimum film thickness)/ (average film thickness)} x 100... (b)

[Method for Producing Adhesive Sheet]

The adhesive sheet 1 which concerns on the said embodiment can be manufactured suitably with the following method.

First, one surface of the first plastic film substrate 11A is coated with an ultraviolet curable adhesive composition (coating step). The film thickness of the adhesive composition at this time is adjusted so that the film thickness of the adhesive layer finally formed may become a desired value in the range of 100-500 micrometers. The coating method of the adhesive composition is not particularly limited, and for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, etc. can be used.

On the other hand, when the pressure-sensitive adhesive composition does not contain a solvent, the drying step is unnecessary after coating as described above.

After the coating step, the coating film of the pressure-sensitive adhesive composition is irradiated with ultraviolet rays, and the pressure-sensitive adhesive composition is pre-cured (pre-curing step). Here, "pre-curing" means a cured state in which the curing reaction is proceeding to the extent that the shape as a coating film is maintained, but the adhesive is still lacking in cohesive force and the curing reaction can proceed further. The amount of ultraviolet light irradiated in the preliminary curing step needs to be smaller than the amount of ultraviolet light irradiated in the main curing step performed later. By performing this pre-curing process, curing shrinkage of the coating film of the pressure-sensitive adhesive composition can be suppressed and occurrence of concavo-convex patterns (substrate concavo-convex patterns) on the first plastic film substrate 11A can be suppressed.

Meanwhile, the pre-curing step may be performed in the presence of oxygen. Usually, when oxygen exists, there exists a tendency for the ultraviolet curing reaction of an adhesive composition to be inhibited. However, in this pre-curing step, since the pressure-sensitive adhesive composition is not completely cured, there is no problem even if oxygen is present.

In the pre-curing step, it is preferable to directly irradiate the ultraviolet ray to the coating film of the adhesive composition, but when the first plastic film substrate 11A is transparent (ultraviolet ray transmittance), it is irradiated from the side of the first plastic film substrate 11A. may do

Although it does not specifically limit as an ultraviolet irradiation apparatus used for irradiation of an ultraviolet-ray, For example, a high-pressure mercury-vapor lamp, a metal halide lamp, a UV-LED lamp, a black light, etc. are mentioned. However, with respect to a high-pressure mercury-vapor lamp or a metal halide lamp, it is preferable to use a hot-ray cut filter from a viewpoint of suppressing the heat_generation|fever from an irradiation part and reducing the thermal contraction of 11 A of 1st plastic film base materials. Moreover, in order to adjust the illuminance and light quantity of an ultraviolet-ray, you may use a photosensitive filter. In addition, for the purpose of promoting ultraviolet curing using ultraviolet rays in a predetermined wavelength range, a wavelength cut-off filter may be used.

The illuminance of the ultraviolet rays in the preliminary curing step is, 1~100mW / cm ² should preferably be preferred, particularly 5~80mW / cm ^2, and furthermore preferably in the 10~50mW / cm ^2. Further, the light quantity of ultraviolet light is, 10~100mJ / cm ² is that it is preferable, in particular 20~80mJ / cm ² are preferred, and further preferably in the 30~60mJ / cm ^2. When the illuminance is ^{less than 1 mW/cm 2} or the amount of light is less than 10 mJ/cm ² , the UV-curable pressure-sensitive adhesive composition is not pre-cured enough, and the pressure-sensitive adhesive composition may start to permeate in the next lamination step. On the other hand, when the illuminance exceeds 100 mW/cm ² or the amount of light exceeds ^{100 mJ/cm 2} , the curing reaction of the UV-curable adhesive composition proceeds excessively, the coating film of the adhesive composition contracts and cures, and the first plastic film substrate 11A is the substrate There is a possibility that uneven patterns may be generated.

After the precuring step, the second plastic film substrate 11B is laminated on the precured coating film of the adhesive composition (lamination step). By performing this lamination, in the next main curing process, it is possible to prevent curing failure of the pressure-sensitive adhesive composition due to the influence of oxygen. If the next main curing step is performed without this lamination, the UV curing reaction of the pressure-sensitive adhesive composition is not completed, the pressure-sensitive adhesive layer obtained is incomplete, and desired physical properties cannot be expressed.

Here, since the coating film of the adhesive composition has a certain degree of hardness by the pre-curing process, the coating film of the adhesive composition is crushed by the lamination of the second plastic film substrate 11B, so that the film thickness is not constant. Neither a problem nor a problem of staining the adhesive composition and contaminating the inside of the process occurs. On the other hand, as a pressure at the time of the said lamination, it is preferable that it is ^{0.1-100 kgf/cm<2>} , and it is especially preferable that it is ^{0.2-2 kgf/m<2>.}

After the lamination process, ultraviolet rays are irradiated to the coating film of the precured adhesive composition to make the adhesive composition main-cured, and it is set as the adhesive layer 12 (main-curing process). Here, "main curing" means the state in which the hardening reaction fully advances and the fluctuation|variation in adhesive force does not generate|occur|produce by the advancing degree of hardening reaction. As the ultraviolet irradiation device used in the main curing step, the same UV irradiation device used in the preliminary curing step can be used. In the main curing step, ultraviolet rays may be irradiated from either side of the first plastic film substrate 11A and the second plastic film substrate 11B. However, the plastic film base material located on the ultraviolet irradiation side needs to be transparent (ultraviolet-ray transmittance).

The amount of ultraviolet light irradiated in the main curing step is required to be larger than the amount of ultraviolet light irradiated in the preliminary curing step. By performing the two-step ultraviolet irradiation in which the amount of light is changed in this way, it is possible to effectively suppress the occurrence of substrate irregularities on the first plastic film substrate 11A and/or the second plastic film substrate 11B.

Illumination of ultraviolet light irradiation in this curing step is preferable that the 1~1000mW / cm ² is preferred, and 5~750mW / cm ^2, and furthermore preferably in the 10~500mW / cm ^2. Further, the light quantity of ultraviolet light is preferably a 100mJ / cm ^2, and greater than, in particular 200~2000mJ / cm ² is not preferable, and further preferably in the 300~1500mJ / cm ^2. When the illuminance of ultraviolet rays is ^{less than 1 mW/cm 2} , the energy required for complete curing of the pressure-sensitive adhesive composition is not obtained, and there is a possibility that a sufficient reaction rate may not be obtained. In addition, when the illuminance of ^{ultraviolet rays exceeds 1000 mW/cm 2} , heat shrinkage occurs in the first plastic film substrate 11A and/or the second plastic film substrate 11B due to the heat generated by ultraviolet irradiation or the reaction heat of the adhesive composition. there is a risk of becoming On the other hand, if the amount of ultraviolet light is 100 mJ/cm ² or less, even if the illuminance is 1 mW/cm ² or more, UV curing does not proceed sufficiently, the cohesive force of the pressure-sensitive adhesive is not sufficiently obtained, and desired physical properties cannot be expressed, or the pressure-sensitive adhesive. There exists a possibility that an unreacted component may remain|survive in it.

UV curing in this step is one time may be irradiated with the light quantity of 100mJ / cm ² than in the survey, or may be irradiated with the light amount of the plurality of times of irradiation 100mJ / cm ² in excess. When irradiating an ultraviolet ray a plurality of times, the light source type, illuminance, and light quantity of the ultraviolet ray employed in each irradiation may be the same or different, respectively.

According to the above method, the pressure-sensitive adhesive sheet 1 can be manufactured while suppressing the occurrence of substrate irregularities on the first plastic film substrate 11A and/or the second plastic film substrate 11B. In addition, by performing the lamination process between the pre-curing process and the main curing process, wet lamination is not required, each process can be performed in an oxygen atmosphere, and the film thickness of the pressure-sensitive adhesive layer 12 to be formed is uniform. can be done with one Furthermore, since it is not necessary to use nitrogen gas consistently in each process, introduction of equipment, etc. which lead to an increase in manufacturing cost is unnecessary.

Here, the said ultraviolet curable adhesive composition is demonstrated. The pressure-sensitive adhesive composition used in the present embodiment is not particularly limited as long as it can produce the pressure-sensitive adhesive sheet 1 in which the generation of the substrate uneven pattern is suppressed by the method described above, but preferred examples will be described below. In other words, the pressure-sensitive adhesive composition used in the present embodiment is a prepolymer (A1) of a (meth)acrylic acid ester having a weight average molecular weight of 20,000 or more and/or a weight average molecular weight of 20,000 or more having a radically polymerizable unsaturated double bond group in the side chain. A pressure-sensitive adhesive composition containing an oligomer (A2) of urethane (meth)acrylate, at least one type of (meth)acrylic acid ester monomer (B), and a photopolymerization initiator (C) (hereinafter referred to as “adhesive composition P” in some cases) ) is preferably used. Since this adhesive composition P does not generate|occur|produce cure shrinkage by an ultraviolet-ray, the said adhesive sheet 1 can be manufactured more easily by using the adhesive composition P. In addition, in this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. Other similar terms are the same.

The number of radically polymerizable unsaturated double bond groups in the (meth)acrylic acid ester prepolymer (A1) and the urethane (meth)acrylate oligomer (A2) needs to be at least one, but the strength and cohesion of the pressure-sensitive adhesive layer From a viewpoint of improving, it is preferable that it is two or more. On the other hand, the above description does not exclude the addition of prepolymers or oligomers having no radically polymerizable unsaturated double bond as other components.

The said (meth)acrylic acid ester prepolymer (A1) means that it has a polymer structure of (meth)acrylic acid ester, and has a radically polymerizable unsaturated double bond in the side chain of this polymer structure. Specifically, the functional group having the active hydrogen in a copolymer of a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, a monomer having a functional group having an active hydrogen, and another monomer that can be employed as desired. With respect to , those in which a radically polymerizable unsaturated double bond is introduced are preferably mentioned. First, the copolymer before introduction of a radically polymerizable unsaturated double bond is demonstrated.

Examples of the (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl ( Meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethyl hexyl (meth) ) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate and the like. These may be used independently and may be used in combination of 2 or more type.

On the other hand, as examples of the monomer having a functional group having an active hydrogen, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxy Hydroxyalkyl (meth)acrylate, monomethylaminoethyl (meth)acrylate, monomethylaminoethyl (meth)acrylate, such as butyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate monoalkylaminoalkyl (meth)acrylates such as ethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, and monoethylaminopropyl (meth)acrylate; and ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These monomers may be used independently and may be used in combination of 2 or more type.

In addition, examples of other monomers used as desired include phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, hydroxyethylated o-phenylphenol ( (meth) acrylic acid ester having a cyclic structure such as meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate; trifluoromethyl (meth) acrylate, trifluoroethyl (meth) acrylic Fluorine-containing (meth)acrylic acid esters such as lactate, tetrafluoropropyl (meth)acrylate, and pentafluoropropyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; ethylene, propylene, isobutylene, etc. olefins; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene-based monomers such as styrene and α-methyl styrene; diene-based monomers such as butadiene, isoprene, and chloroprene; nitriles such as acrylonitrile and methacrylonitrile Monomer; Acrylamides, such as acrylamide, N-methyl acrylamide, and N,N- dimethyl acrylamide, etc. are mentioned. These may be used independently and may be used in combination of 2 or more type.

By superposing|polymerizing each said monomer by a conventional method, it is set as a copolymer. The copolymer of the said (meth)acrylic acid ester may be used individually by 1 type, and may be used in combination of 2 or more type.

Next, by introducing a radically polymerizable unsaturated double bond group into a side chain through a functional group having an active hydrogen of the copolymer of (meth)acrylic acid ester, a prepolymer (A1) of (meth)acrylic acid ester will be described. .

The introduction of the radically polymerizable unsaturated double bond into the functional group having an active hydrogen in the copolymer may be carried out by, for example, an addition reaction of a compound having both a radically polymerizable unsaturated double bond and an active hydrogen-reactive group. have. As said active hydrogen reactive group, an isocyanate group, a glycidyl group, etc. are mentioned, for example.

Specific examples of the compound having both a radically polymerizable unsaturated double bond and an active hydrogen reactive group include acryloyloxyethyl isocyanate, acryloyloxypropyl isocyanate, methacryloyloxyethyl isocyanate, methacryloyloxypropyl Isocyanate, allyl isocyanate, glycidyl (meth)acrylate, etc. are mentioned preferably.

The above addition reaction is preferably performed, for example, at a temperature of 25 to 60° C. for about 6 to 48 hours. Moreover, in said addition reaction, it is also preferable to use organotin compounds, such as dibutyltin dilaurate, a substituted amine compound, etc. as a catalyst as needed.

The urethane (meth) acrylate oligomer (A2) is obtained by, for example, esterifying a polyurethane oligomer obtained by the reaction of polyether polyol or polyester polyol with polyethylene isocyanate by reaction with (meth) acrylic acid. can The oligomer (A2) of this urethane (meth)acrylate may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, the prepolymer (A1) of (meth)acrylic acid ester and the oligomer (A2) of urethane (meth)acrylate can also be used together.

The weight average molecular weight of the (meth)acrylic acid ester prepolymer (A1) and the urethane (meth)acrylate oligomer (A2) is 20,000 or more, preferably 25,000 to 80,000, and particularly preferably 30,000 to 60,000. . When this weight average molecular weight is 20,000 or more, the adhesive composition P becomes a thing with little cure shrinkage. In addition, the weight average molecular weight in this specification is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

The (meth)acrylic acid ester monomer (B) is added in order to reduce the viscosity of the adhesive composition P and improve the coatability. Although it does not specifically limit as a (meth)acrylic acid ester monomer (B), An ultraviolet curable thing which has one or more reactive sites like a carbon-carbon double bond in 1 molecule is preferable. The (meth)acrylic acid ester monomer (B) having such a reactive moiety is irradiated with ultraviolet light between the (meth)acrylic acid ester monomers (B) or the (meth)acrylic acid ester prepolymer (A1) and / or the urethane (meth) ) In order to form a crosslinked structure with the oligomer (A2) of an acrylate, the cohesive force of the adhesive layer obtained is improved, and it can prevent effectively that problems, such as staining, arise.

As the (meth)acrylic acid ester monomer (B), a monomer constituting the above-mentioned (meth)acrylic acid ester prepolymer (A1), a polyfunctional acrylate having two or more reactive sites such as carbon-carbon double bonds, etc. It can be exemplified preferably.

Specific examples of the polyfunctional acrylate include 1,4-butanedioldi(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, neopentylglycoldi(meth)acrylate, polyethylene glycoldi( Meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di ( Meth) acrylate, ethylene oxide-modified di(meth)acrylate, di(acryloxyethyl) isocyanurate, allylated cyclohexyldi(meth)acrylate, dimethyloldicyclopentanedi(meth)acrylate, ethylene Oxide-modified hydrophthalic acid di(meth)acrylate, tricyclodecanedimethanol (meth)acrylate, neopentylglycol-modified trimethylolpropanedi(meth)acrylate, adamantanedi(meth)acrylate, 9, 9- Bifunctional types such as bis[4-(2-acryloyloxyethoxy)phenyl]fluorene; trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid modified dipentaerythritol tri Trifunctional types such as (meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, and tris(acryloxyethyl)isocyanurate; diglycerin tetra(meth) tetrafunctional type such as acrylate and pentaerythritol tetra(meth)acrylate; pentaerythritol type such as propionic acid modified dipentaerythritol penta(meth)acrylate; dipentaerythritol hexa(meth)acrylate, caprolactone modified dipentaerythritol 6 functional types, such as hexa (meth)acrylate, etc. are mentioned.

The content of the (meth)acrylic acid ester monomer (B) in the adhesive composition P is 50 to 100 parts by mass in total of the (meth)acrylic acid ester prepolymer (A1) and the urethane (meth)acrylate oligomer (A2) It is preferable that it is 1900 mass parts, It is especially preferable that it is 75-900 mass parts, Furthermore, it is preferable that it is 100-400 mass parts.

By containing a photoinitiator (C), the adhesive composition P can harden the ultraviolet curable component in the adhesive composition P efficiently, and can reduce polymerization hardening time and the irradiation amount of an ultraviolet-ray.

As the photoinitiator (C), for example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoaceto Phenone, 2, 2-dimethoxy-2-phenylacetophenone, 2, 2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxy Cyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy- 2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4, 4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methyl anthraquinone, 2-ethyl anthraquinone, 2-tertiary- Butyl anthraquinone, 2-amino anthraquinone, 2-methylthioquisanthone, 2-ethylthioquisanthone, 2-chlorothioquisanthone, 2,4-dimethylthioquisanthone, 2,4-diethylthioquisanthone, Benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethyl aminobenzoic acid ester, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2, 4, 6-trimethyl Benzoyl-diphenyl-phosphine oxide etc. are mentioned. These may be used independently and may be used in combination of 2 or more type.

The content of the photoinitiator (C) in the adhesive composition P is the sum of the (meth)acrylic acid ester prepolymer (A1) and the urethane (meth)acrylate oligomer (A2) (ultraviolet-curable (meth)acrylic acid ester monomer (B) ), it is preferably 0.01 to 10 parts by mass, particularly preferably 0.1 to 5 parts by mass, further 0.2 to 100 parts by mass (total including the (meth)acrylic acid ester monomer (B)). It is preferable that it is -2 mass parts.

The pressure-sensitive adhesive composition P contains, if desired, various additives commonly used in acrylic pressure-sensitive adhesives, such as silane coupling agents, antistatic agents, tackifiers, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, refractive index modifiers, and the like. may do

On the other hand, it is preferable that the adhesive composition P does not contain a solvent. When the adhesive composition P contains a solvent, it is difficult to easily form the adhesive layer 12 with a film thickness of 100-500 micrometers. Furthermore, when the adhesive composition P contains a solvent, a drying process is required, and a photoinitiator (C) may decompose|disassemble, volatilize, and sublimate. Since the adhesive composition P contains the said (meth)acrylic acid ester monomer (B) which is a low molecular weight body, even if it does not contain a solvent, it is possible to adjust the viscosity suitable for coating.

[Optical laminate]

The pressure-sensitive adhesive sheet 1 according to the present embodiment can be suitably used for various optical laminates having a thick pressure-sensitive adhesive layer as a component. Although the adhesive layer 12 of the adhesive sheet 1 which concerns on this embodiment is a thick film, the surface does not have the unevenness|corrugation resulting from a base material uneven|corrugated pattern, and it is excellent also in film thickness precision. For this reason, the optical laminated body obtained using the adhesive sheet 1 of this embodiment becomes a thing excellent also in an optical characteristic.

Here, the optical laminate is not limited at all as long as it is a structure that requires a thick pressure-sensitive adhesive layer. For example, two glass substrates (or plastic films) on which a transparent conductive film made of tin-doped indium oxide (ITO) is laminated. Thus, a laminate formed by sandwiching the pressure-sensitive adhesive layer so that the transparent conductive film side is in contact with the pressure-sensitive adhesive layer, or a laminate formed by filling the gap between hard plates formed by laminating a polarizing plate or a retardation plate on a glass substrate with a thick pressure-sensitive adhesive layer, etc. Preferably, it is mentioned.

The embodiment described above is described in order to facilitate the understanding of the present invention, and is not described in order to limit the present invention. Accordingly, each element disclosed in the above embodiments is intended to include all design changes and equivalents falling within the technical scope of the present invention.

For example, another layer may be laminated|stacked on the surface on the opposite side to the adhesive layer 12 side in the 1st plastic film base material 11A and/or the 2nd plastic film base material 11B.

Hereinafter, the present invention will be more specifically described by way of examples and the like, but the scope of the present invention is not limited to these examples and the like.

[Examples 1 to 5, Comparative Examples 1 to 4]

(1) Preparation of prepolymer

After mixing 60 parts by mass of 2-ethylhexyl acrylate, 30 parts by mass of isobornyl acrylate, and 10 parts by mass of hydroxyethyl acrylate, 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF) as a photoinitiator , Ilgacure 184) was added in 0.10 parts by mass. This mixture was irradiated with ultraviolet rays in a nitrogen atmosphere and stirred sufficiently to obtain a copolymer. To 100 parts by mass of the obtained copolymer, 0.10 parts by mass of 2-acryloyloxyethyl isocyanate and a catalytic amount of dibutyltin dilaurate were added, and the prepolymer ( A1) was obtained.

Here, the above-mentioned weight average molecular weight (Mw) is a weight average molecular weight in terms of polystyrene measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement conditions>

・GPC measuring device: HLC-8020, manufactured by Tosoh Corporation

・GPC column (pass in the following order): manufactured by Tosoh Corporation

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000 HXL

・Measurement solvent: tetrahydrofuran

・Measurement temperature: 40℃

(2) Preparation of adhesive composition

To 100 parts by mass of the prepolymer (A1) obtained above, 60 parts by mass of isobornyl acrylate and 60 parts by mass of 2-ethylhexyl acrylate as (meth)acrylic acid ester monomer (B) are added, stirred sufficiently, and liquid phase A mixture was obtained. With respect to 100 parts by mass of the obtained liquid mixture, 0.40 parts by mass of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide lucirin (manufactured by BASF, lucirin TPO) as a photopolymerization initiator (C) is added, and the mixture is sufficiently stirred, An ultraviolet curable adhesive composition was obtained.

(3) Preparation of adhesive sheet

As the first plastic film substrate, a medium-peelable release film (manufactured by Lintec, SP-PET752150, thickness: 75 µm) in which one side of a polyethylene terephthalate film was peeled off with a silicone-based release agent was prepared. In addition, as a second plastic film substrate, a light-peelable release film (manufactured by Lintec, SP-PET381130, thickness: 38 µm) in which one side of a polyethylene terephthalate film was peeled off with a silicone-based release agent was prepared.

After coating the peeling treatment surface of the first plastic film substrate with the ultraviolet curable adhesive composition obtained above with a knife coater, the coating film side of the adhesive composition is irradiated with ultraviolet rays of the illuminance and light quantity shown in Table 1 to prepare the adhesive composition pre-cured. In this pre-curing process, as an ultraviolet irradiation device, the eye ultraviolet curing device US2-0801<2> manufactured by Eye Graphics Co., Ltd. was used.

Next, the 2nd plastic film base material 11B was laminated to the coating film of the adhesive composition precured so that the peeling-processed surface might become the coating film side of the adhesive composition. Lamipaca LPD3214 manufactured by Fujipla Co., Ltd. was used for the lamination, and the lamination pressure was 0.5 kgf/cm ² . Then, from the 2nd plastic film base material side, the ultraviolet-ray of the illuminance and light quantity shown in Table 1 was irradiated, the adhesive composition was main-cured, the adhesive layer was formed, and the adhesive sheet was obtained. In this main curing step, as an ultraviolet irradiation device, an eye UV curing device US2-0801<2> manufactured by Eye Graphics Co., Ltd. was used. The thickness of the adhesive layer in the obtained adhesive sheet was 200 micrometers. In addition, this value of the thickness of an adhesive layer shows the value obtained by rounding off the 1st decimal place of the average film thickness mentioned later.

[Test Example 1] (Evaluation of cured state)

From the pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples, the second plastic film substrate, which is a light-peelable release film, was peeled off. At this time, when the adhesive did not migrate to the 2nd plastic film base material side and it could peel, it determined that the cured state of an adhesive was favorable (circle). In addition, when a part of the adhesive moved to the 2nd plastic film base material side, it was judged that the cured state of the adhesive was bad ((triangle|delta)). On the other hand, when the pressure-sensitive adhesive layer was cohesively fractured when the second plastic film substrate was peeled off, it was determined that the cured state of the pressure-sensitive adhesive was extremely poor (x). A result is shown in Table 1.

[Test Example 2] (Confirmation of substrate uneven pattern)

What cut out the adhesive sheet obtained by the Example or the comparative example in the square of 1 m in length and width each was made into the sample. A projector that emits white light (NEC Corporation, ViewLight NP-L50WJD), the sample, and a screen (KIC Corporation, floor type KPR-100) are placed in that order at intervals of 0.9 m and 0.3 m, respectively (the sample and the screen are parallel), and the shadows projected on this screen were visually confirmed. And the number of shadows of 50 cm or more in length and 3 mm or more in width was counted, and this was made into the number of base material uneven|corrugated patterns. A result is shown in Table 1. When the number of this base material uneven|corrugated pattern is 1 or less, it is judged as good, and when it is 2 or more, it is judged as bad. On the other hand, about Comparative Example 4, since the cured state of the pressure-sensitive adhesive was extremely poor, this test was not performed.

[Test Example 3] (Measurement of film thickness variation)

The sample (1 m x 1 m) produced in Test Example 1 was further divided into 10 (length 20 cm x width 50 cm), and it was set as the sample of this test. From this sample, the second plastic film substrate, which is a light release type release film, and the first plastic film substrate, which is a medium release type release film, were sequentially peeled off, and the obtained pressure-sensitive adhesive layer was measured for film thickness at any one point. By performing the same measurement with respect to 10 samples, the film thickness of 10 points|pieces was measured at random. For the measurement of the film thickness, a J-type digital indicator manufactured by Techrok Corporation was used.

And the average film thickness, the maximum film thickness, and the minimum film thickness were derived|led-out, and the arbitrary larger one of the value computed by the following formulas (a) and (b) was made into the dispersion|variation (%) of the film thickness of an adhesive layer. A result is shown in Table 1. When the dispersion|variation in this film thickness is 5 % or less, when it exceeds 5 %, it is judged as good, and when it exceeds 5 %, it is inferior. On the other hand, about Comparative Example 4, since the cured state of the pressure-sensitive adhesive was extremely poor, this test could not be performed.

{(maximum film thickness-average film thickness)/ (average film thickness)}×100… (a)

{(average film thickness - minimum film thickness)/ (average film thickness)} x 100... (b)

[Test Example 4] (Comprehensive judgment)

In the said Test Examples 1-3, only when it was judged that all were favorable, comprehensive judgment was made into good (circle), and the other was judged as bad (x). A result is shown in Table 1.

[Test Example 5] (Evaluation of optical laminate)

The pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples was cut into a square having a length of 100 mm and a width of 100 mm. On the other hand, when the substrate concavo-convex pattern is present on the pressure-sensitive adhesive sheet at the time of cutting, the substrate concavo-convex pattern is cut to be included in the square.

On the other hand, a glass with a transparent conductive film in which a transparent conductive film made of ITO having a thickness of 155 nm is formed on one side of an alkali-free glass substrate having a length of 100 mm, a width of 100 mm, and a thickness of 0.7 mm (manufactured by Geometics, product name "Glass with FLAT ITO film") Chapter 2 was prepared. Then, both release films are peeled off from the pressure-sensitive adhesive sheet cut above, and the pressure-sensitive adhesive layer is sandwiched by two pieces of glass with a transparent conductive film so that the exposed pressure-sensitive adhesive layer is in contact with the transparent conductive film side of the glass with a transparent conductive film. By doing so, an optical laminate was obtained.

The obtained optical laminated body was stored at 50 degreeC and 50%RH for 7 days, and the following references|standards evaluated the external appearance of this optical laminated body after that. A result is shown in Table 1.

(double-circle): There was no external abnormality.

(circle): At the time of optical laminated body production, it was recognized that it was a pattern resulting from an adhesive layer, but there was no external appearance abnormality after the said storage.

x: Even after the said storage, what seems to be a pattern resulting from an adhesive layer was visually recognized.

× ×: After the storage, floating and foaming occurred at the interface with the pressure-sensitive adhesive layer.

pre-curing process
UV-rays of the main curing process
UV-rays Hardening
state write
uneven pattern film thickness
gap
Synthesis
Judgment

of optical laminate
Exterior illuminance
(mW/cm ² ) amount of light
(mJ/cm ² ) illuminance
(mW/cm ² ) amount of light
(mJ/cm ² )
Judgment
Count
% Example 1 10 10 300 1000 ○ 0 1.5 ○ ◎ Example 2 5 90 300 1000 ○ 0 1.0 ○ ◎ Example 3 80 10 300 1000 ○ 0 2.5 ○ ◎ Example 4 80 50 300 1000 ○ One 1.0 ○ ○ Example 5 30 30 400 500 ○ 0 3.0 ○ ◎ Comparative Example 1 120 10 300 1000 ○ 3 2.0 × × Comparative Example 2 50 150 300 1000 ○ 4 1.0 × × Comparative Example 3 30 30 400 200 △ 0 2.5 × ×× Comparative Example 4 One 2 0 0 × - - × - Comparative Example 5 0 0 300 1000 ○ 0 8.0 × ××

As shown in Table 1, the pressure-sensitive adhesive sheet obtained in the Example had one or less base material uneven patterns. Moreover, as for the adhesive layer in the adhesive sheet obtained in the Example, the hardened state was favorable, and the dispersion|variation in film thickness was also small. Therefore, the adhesive sheet obtained in the Example was favorable in comprehensive judgment. Moreover, the adhesive sheet (pressure-sensitive adhesive layer) obtained in the Example was excellent in the optical characteristic (appearance) also in an optical laminated body.

The adhesive sheet of this invention is suitable as adhesive sheets for optical members, such as a display and a touch panel, for example.

One… adhesive sheet
11A… first plastic film substrate
11B… second plastic film substrate
12… adhesive layer

Claims (8)

A first plastic film substrate having a thickness of 10-200 μm, and
A second plastic film substrate having a thickness of 10-200 μm, and
A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 100 to 500 μm sandwiched between the first plastic film substrate and the second plastic film substrate,
When a projector emitting white light, a sample from which the pressure-sensitive adhesive sheet is cut to form a square of 1 m in length and width, and a screen are arranged at intervals of 0.9 m and 0.3 m, respectively, in that order, a shadow of 50 cm or more in length and 3 mm or more in width As a pressure-sensitive adhesive sheet, characterized in that the base material uneven pattern projected on the screen is one or less. The method according to claim 1,
The pressure-sensitive adhesive sheet, characterized in that the variation in the film thickness of the pressure-sensitive adhesive layer is 5% or less. The method according to claim 1,
The pressure-sensitive adhesive layer is a pressure-sensitive adhesive sheet, characterized in that the pressure-sensitive adhesive layer formed by coating and curing an ultraviolet curable pressure-sensitive adhesive composition. As the manufacturing method of the adhesive sheet of Claim 3,
coating the pressure-sensitive adhesive composition on one surface of the first plastic film substrate;
A pre-curing step of pre-curing the pressure-sensitive adhesive composition by irradiating ultraviolet rays to the coating film of the pressure-sensitive adhesive composition;
laminating the second plastic film substrate to the coating film of the pre-cured adhesive composition;
Through the first plastic film substrate or the second plastic film substrate, by irradiating ultraviolet rays to the coating film of the pre-cured adhesive composition, the pressure-sensitive adhesive composition is main-cured to form a pressure-sensitive adhesive layer,
A method for producing an adhesive sheet, wherein the amount of ultraviolet light irradiated in the main curing step is larger than the amount of ultraviolet light irradiated in the pre-curing step. 5. The method according to claim 4,
The illuminance of the ultraviolet ray irradiated in the pre-curing process is 1 to 100 mW/cm ² , and the amount of light is 10 to 100 mJ/cm ² ,
The illuminance of the ultraviolet ray for irradiation in this curing step is 1~1000mW / cm ^2, light quantity production method of the adhesive sheet, characterized in that more than 100mJ / cm ^2. 4. The method according to claim 3,
Said adhesive composition does not contain a solvent, The adhesive sheet characterized by the above-mentioned. 4. The method according to claim 3,
The adhesive composition,
A prepolymer of (meth)acrylic acid ester having a radically polymerizable unsaturated double bond having a weight average molecular weight of 20,000 or more and / or an oligomer of urethane (meth)acrylate having a weight average molecular weight of 20,000 or more;
at least one (meth)acrylic acid ester monomer;
A photoinitiator is contained, The adhesive sheet characterized by the above-mentioned. The said adhesive layer obtained from the adhesive sheet in any one of Claims 1-3, 6 and 7 was provided at least, The optical laminated body characterized by the above-mentioned.

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