JP2017155074A - Adhesive sheet and method of manufacturing optical product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive sheet whose adhesive force decreases by irradiation with a light beam having a wavelength of 385 nm and which is excellent in storage stability under a fluorescent lamp, and to provide a method of manufacturing an optical product using the adhesive sheet.SOLUTION: The adhesive sheet includes a substrate and an adhesive layer laminated on at least one surface side of the substrate and comprising an ultraviolet-curable adhesive. The ultraviolet-curable adhesive is formed from an adhesive composition containing: (a) a photopolymerization initiator which is cleaved by irradiation with a light beam having a wavelength of 385 nm; and (b) a radical generator which is not cleaved by irradiation with a light beam having a wavelength of 385 nm and generates radicals by cleavage of the photopolymerization initiator.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive sheet that can be attached to a workpiece and peeled from the workpiece, and a method for producing an optical product using the pressure-sensitive adhesive sheet.

  Various mobile electronic devices such as smartphones and tablet terminals in recent years include a display using a display module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL) element, and the like. It is also becoming more and more a touch panel.

  The display as described above is configured by laminating various optical members. As an example, the touch panel display is laminated with a display module (for example, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, etc.) via an adhesive layer. A film with a transparent conductive film and a cover glass with a transparent conductive film laminated thereon via an adhesive layer are configured.

  In manufacturing a display using the various optical members described above, it is necessary to move the optical member from one position to another position or to stack a certain optical member on another optical member. At that time, by sticking an adhesive sheet to the optical member and handling the adhesive sheet, the optical member to which the adhesive sheet is attached may be subjected to a desired operation.

  Such an adhesive sheet has a predetermined adhesive force so that unintentional peeling does not occur during the work on the optical member, and can be easily peeled off from the optical member after the work on the optical member. It is necessary to have.

  As such a pressure-sensitive adhesive sheet, one having a pressure-sensitive adhesive layer made of an ultraviolet curable pressure-sensitive adhesive can be used. In such a pressure-sensitive adhesive sheet, the pressure-sensitive adhesive is cured by irradiating with ultraviolet rays to reduce the pressure-sensitive adhesive force, so that it can be easily peeled off from the adherend.

  Conventionally, a device using a metal halide or a high-pressure mercury lamp as a light source has been used as the above-described device for irradiating ultraviolet rays. However, in recent years, instead of these, ultraviolet light-emitting diodes (also referred to as “ultraviolet LEDs” in this specification) are used. ) Has been proposed (for example, Patent Document 1).

  However, when an ultraviolet LED is used as a light source, there is a tendency that curing of the pressure-sensitive adhesive layer provided in the above pressure-sensitive adhesive sheet tends to be insufficient due to reasons such as low diffusibility, low heat generation, and narrow wavelength range. was there.

  In order to solve the above problem, the adhesive sheet disclosed in Patent Document 2 has been proposed, although the application is a device-related member such as a semiconductor wafer. In such a pressure-sensitive adhesive sheet, the adhesive strength can be sufficiently reduced even when the ultraviolet LED is irradiated by blending a predetermined amount of a photopolymerization initiator having a mass absorption coefficient of 365 nm in a predetermined range with the pressure-sensitive adhesive.

JP 2006-040944 A International Publication No. WO2014 / 142085

  However, when the pressure-sensitive adhesive sheet of Patent Document 2 is stored under a fluorescent lamp, the photopolymerization initiator may be cleaved by the light from the fluorescent lamp, and the curing of the pressure-sensitive adhesive may proceed. When the curing of the pressure-sensitive adhesive progresses during storage of the pressure-sensitive adhesive sheet, a desired pressure-sensitive adhesive force cannot be stably exerted on the adherend during actual use. As described above, it is difficult to say that the conventional adhesive sheet that reduces the adhesive strength with the ultraviolet LED has sufficient storage stability under a fluorescent lamp.

  Here, as an ultraviolet LED, one emitting a light beam having a wavelength of 385 nm is being used recently.

  The present invention has been made in view of the above circumstances, and uses a pressure-sensitive adhesive sheet that has reduced adhesive strength when irradiated with light having a wavelength of 385 nm and has excellent storage stability under a fluorescent lamp, and the pressure-sensitive adhesive sheet. It is an object of the present invention to provide a method for manufacturing an optical product.

  In order to achieve the above object, first, the present invention includes a base material, and an adhesive layer made of an ultraviolet curable adhesive, which is laminated on at least one surface side of the base material. Adhesive (a) is a photopolymerization initiator that is cleaved by irradiation with light having a wavelength of 385 nm, and (b) is not cleaved by irradiation with light having a wavelength of 385 nm, and generates radicals by cleavage of the photopolymerization initiator. Provided is a pressure-sensitive adhesive sheet that is formed from a pressure-sensitive adhesive composition containing a radical generator (Invention 1).

  2ndly this invention is equipped with the base material and the adhesive layer which consists of an ultraviolet curable adhesive laminated | stacked on the at least one surface side of the said base material, The said ultraviolet curable adhesive is (a). A photopolymerization initiator having a maximum value of mass extinction coefficient of light in a wavelength region of 370 to 390 nm of 200 ml / g · cm to 10,000 ml / g · cm, and (b) a light in a wavelength region of 370 to 390 nm. There is provided a pressure-sensitive adhesive sheet characterized by being formed from a pressure-sensitive adhesive composition containing a radical generator having a maximum value of mass extinction coefficient of less than 200 ml / g · cm (Invention 2).

  When the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet according to the above inventions (Inventions 1 and 2) is irradiated with light having a wavelength of 385 nm, the photopolymerization initiator is cleaved to generate radicals, and the radicals are also induced by the radicals. Generate radicals. In this way, the radical generator acts as a chain transfer agent, so that even if the content of the photopolymerization initiator is reduced, the generated radical can sufficiently cure the ultraviolet curable adhesive, and thus the adhesive strength. Is sufficiently reduced. On the other hand, since the content of the photopolymerization initiator can be reduced, the curing of the ultraviolet curable adhesive is difficult to proceed even under a fluorescent lamp. Therefore, even when the adhesive sheet is stored under a fluorescent lamp. Thus, it is possible to stably exhibit a good adhesive force to the adherend. That is, the pressure-sensitive adhesive sheet according to the above invention is excellent in adhesive strength reduction by irradiation with light having a wavelength of 385 nm and excellent in storage stability under a fluorescent lamp.

  In the said invention (invention 1 and 2), content of the said photoinitiator in the said adhesive composition is 0.3 mass with respect to 100 mass parts of ultraviolet curable components in the said ultraviolet curable adhesive. The content of the radical generator in the pressure-sensitive adhesive composition is preferably 0. 5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the ultraviolet-curable component in the ultraviolet-curable adhesive. It is preferably 8 parts by mass or more and 7.0 parts by mass or less (Invention 3).

  In the said invention (invention 1-3), it is preferable that the said ultraviolet curable adhesive contains an ultraviolet non-curable polymer and an ultraviolet curable monomer and / or oligomer (invention 4).

  In the said invention (invention 4), it is preferable that the said ultraviolet non-curable polymer has a crosslinked structure through a crosslinking agent (invention 5).

  In the said invention (invention 1-5), it is preferable that the adhesive force with respect to the silicon mirror wafer of the said adhesive sheet before light irradiation with a wavelength of 385 nm is 8000 mN / 25mm or more and 300000 mN / 25mm or less (invention 6).

  In the said invention (invention 1-6), it is preferable that the adhesive force with respect to the silicon mirror wafer of the said adhesive sheet after the light irradiation of wavelength 385nm is 1000 mN / 25mm or less (invention 7).

  In the said invention (invention 1-7), ratio of the adhesive force with respect to the silicon mirror wafer of the said adhesive sheet after light irradiation of wavelength 385nm with respect to the adhesive force with respect to the silicon mirror wafer of the said adhesive sheet before light irradiation of wavelength 385nm is the following. It is preferably 0.1% or more and 15% or less (Invention 8).

  It is preferable that the adhesive sheet which concerns on the said invention (invention 1-8) is used for manufacture of an optical product (invention 9).

  Thirdly, the present invention includes a step of attaching the pressure-sensitive adhesive sheet (Invention 1 to 9) to an optical member via the pressure-sensitive adhesive layer, and a step of performing a desired operation on the optical member to which the pressure-sensitive adhesive sheet is attached. Irradiating the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet attached to the optical member with a light beam having a wavelength of 385 nm to reduce the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer; and peeling the pressure-sensitive adhesive sheet from the optical member A method of manufacturing an optical product, comprising:

  The pressure-sensitive adhesive sheet according to the present invention has a low adhesive strength when irradiated with light having a wavelength of 385 nm, and is excellent in storage stability under a fluorescent lamp. According to such an adhesive sheet, an optical product can be manufactured stably.

Hereinafter, embodiments of the present invention will be described.
[Adhesive sheet]
The pressure-sensitive adhesive sheet according to the present embodiment is affixed to a work, and after a desired operation is performed on the work in that state, the pressure-sensitive adhesive sheet is peeled off from the work. Although it does not specifically limit as a workpiece | work, The optical member mentioned later is preferable.

  The pressure-sensitive adhesive sheet according to this embodiment includes a base material and a pressure-sensitive adhesive layer laminated on at least one surface side of the base material. A release film may be laminated on the surface of the pressure-sensitive adhesive layer opposite to the base material. This release film is peeled and removed during use of the pressure-sensitive adhesive sheet, and protects the pressure-sensitive adhesive layer until then.

1. Adhesive layer The adhesive layer in this embodiment consists of an ultraviolet curable adhesive. First, the ultraviolet curable adhesive is:
(A) a photopolymerization initiator that is cleaved by irradiation with light having a wavelength of 385 nm;
(B) It is formed from a pressure-sensitive adhesive composition containing a radical generator that is not cleaved by irradiation with light having a wavelength of 385 nm and that generates radicals by cleavage of the photopolymerization initiator. 2,
(A) a photopolymerization initiator having a maximum value of a mass extinction coefficient of light in a wavelength region of 370 to 390 nm of 200 ml / g · cm or more and 10,000 ml / g · cm or less;
(B) It is formed from the adhesive composition containing the radical generating agent whose maximum value of the mass extinction coefficient of the light ray in the wavelength range of 370 to 390 nm is less than 200 ml / g · cm.

  In the pressure-sensitive adhesive layer made of the ultraviolet curable pressure-sensitive adhesive formed from the pressure-sensitive adhesive composition, the photopolymerization initiator and the radical generator are used in combination. When the pressure-sensitive adhesive layer is irradiated with light having a wavelength of 385 nm, the photopolymerization initiator is cleaved to generate radicals, which are induced by the radicals and the radical generator also generates radicals. In this way, the radical generator acts as a chain transfer agent, so that even if the content of the photopolymerization initiator is reduced, the generated radical can sufficiently cure the ultraviolet curable adhesive, and thus the adhesive strength. Is sufficiently reduced. In addition, the light irradiation time can be shortened by such an action, thereby increasing the production efficiency. On the other hand, since the content of the photopolymerization initiator can be reduced, the curing of the ultraviolet curable adhesive is difficult to proceed even under a fluorescent lamp. Therefore, even when the adhesive sheet is stored under a fluorescent lamp. In addition, it is possible to stably exhibit a good adhesive force to the adherend (workpiece). That is, the pressure-sensitive adhesive sheet according to the present embodiment is excellent in adhesive strength reduction due to irradiation with light having a wavelength of 385 nm and excellent in storage stability under a fluorescent lamp.

(1) Ultraviolet curable adhesive main agent The adhesive composition forming the ultraviolet curable adhesive in the present embodiment contains an ultraviolet curable adhesive main agent in addition to the photopolymerization initiator and the radical generator, and further a crosslinking agent. It may contain. The ultraviolet curable adhesive main agent is not particularly limited as long as it is cured by radicals generated by irradiation with light having a wavelength of 385 nm. Such an ultraviolet curable adhesive main agent may contain an ultraviolet curable monomer and / or oligomer, or contains an ultraviolet curable polymer and an ultraviolet curable monomer and / or oligomer. It may be a thing, an ultraviolet curable polymer may be contained, and an ultraviolet curable polymer and an ultraviolet curable monomer and / or oligomer may be contained. Further, it may contain an ultraviolet curable polymer, an ultraviolet non-curable polymer, and an ultraviolet curable monomer and / or oligomer. Among them, an ultraviolet non-curable polymer, an ultraviolet curable monomer and / or an oligomer, which can easily increase the adhesive strength before ultraviolet curing and can increase the difference from the adhesive strength after ultraviolet curing, The ultraviolet curable adhesive main ingredient containing is preferable. Among the above components, the ultraviolet curable monomer and / or oligomer and the ultraviolet curable polymer correspond to the ultraviolet curable component.

(1-1) UV non-curable polymer When the UV curable adhesive main component contains a UV non-curable polymer, the UV non-curable polymer may be contained as it is in the pressure-sensitive adhesive layer. At least a part thereof may have a crosslinked structure by performing a crosslinking reaction with the crosslinking agent. Examples of the UV non-curable polymer include acrylic polymers, phenoxy resins, urethane resins, polyester resins, rubber resins, acrylic urethane resins, and silicone resins. Among them, acrylic polymers that can easily control the adhesive force. Polymers are preferred. Hereinafter, the case where an acrylic polymer is used will be described in detail. In the present specification, the term “polymer” includes the concept of “copolymer”.

  A conventionally known acrylic polymer can be used as the acrylic polymer. The acrylic polymer may be a homopolymer formed from one type of acrylic monomer, may be a copolymer formed from a plurality of types of acrylic monomers, or may be one type or a plurality of types. It may be a copolymer formed from various types of acrylic monomers and monomers other than acrylic monomers. Specific types of the compound that becomes the acrylic monomer are not particularly limited, and specific examples include (meth) acrylic acid, (meth) acrylic acid ester, and derivatives thereof (acrylonitrile, itaconic acid, and the like). In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms.

  Specific examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n- Hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) (Meth) acrylates having a chain skeleton such as acrylate; cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, tetrahydro (Meth) acrylates having a cyclic skeleton such as rufuryl (meth) acrylate and imide acrylate; hydroxy groups such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate (Meth) acrylates having a reactive functional group other than hydroxy groups such as glycidyl (meth) acrylate and N-methylaminoethyl (meth) acrylate. Examples of monomers other than acrylic monomers include olefins such as ethylene and norbornene, vinyl acetate, and styrene. When the acrylic monomer is an alkyl (meth) acrylate, the alkyl group preferably has 1 to 18 carbon atoms.

  When the pressure-sensitive adhesive composition forming the ultraviolet curable pressure-sensitive adhesive in the present embodiment contains a crosslinking agent, the acrylic polymer preferably has a reactive functional group that reacts with the crosslinking agent. The type of the reactive functional group is not particularly limited, and may be appropriately determined based on the type of the crosslinking agent.

  For example, when the crosslinking agent is a polyisocyanate compound, examples of the reactive functional group that the acrylic polymer has include a hydroxy group, a carboxy group, and an amino group. When the crosslinking agent is an epoxy compound, examples of the reactive functional group that the acrylic polymer has include a carboxy group, an amino group, and an amide group. When the crosslinking agent is a chelate compound, examples of the reactive functional group possessed by the acrylic polymer include a hydroxy group, a carboxy group, and an epoxy group.

  The method for introducing the reactive functional group into the acrylic polymer is not particularly limited. For example, the acrylic polymer is formed using the monomer having the reactive functional group, and the structure is based on the monomer having the reactive functional group. Examples thereof include a method in which a unit is contained in a polymer skeleton. For example, when a hydroxy group is introduced into an acrylic polymer, the acrylic polymer may be formed using a monomer having a hydroxy group such as 2-hydroxyethyl acrylate. Moreover, what is necessary is just to form an acrylic polymer using the monomer which has carboxy groups, such as acrylic acid, when introducing a carboxy group into an acrylic polymer.

  When the acrylic polymer has a reactive functional group, the proportion of the mass of the structural portion derived from the monomer having a reactive functional group in the total mass of the acrylic polymer is preferably 1% by mass or more. In particular, it is preferably 2% by mass or more. Further, the ratio is preferably 20% by mass or less, and particularly preferably 10% by mass or less. When the ratio is in the above range, the degree of crosslinking can be improved.

  The weight average molecular weight (Mw) of the acrylic polymer is preferably 10,000 or more, particularly preferably 100,000 or more. The weight average molecular weight of the acrylic polymer is preferably 2 million or less, and particularly preferably 1.5 million or less. When the weight average molecular weight is in the above range, good adhesiveness can be exhibited, and the film forming property at the time of coating can be ensured satisfactorily. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

(1-2) Ultraviolet curable monomer and / or oligomer An ultraviolet curable monomer and / or oligomer (hereinafter referred to as “ultraviolet curable compound”) has an ultraviolet curable group and is irradiated with ultraviolet rays. It is a compound to be polymerized and has a lower molecular weight than the ultraviolet curable polymer described later.

  The ultraviolet curable group that the ultraviolet curable compound has is, for example, a group containing an ultraviolet curable carbon-carbon double bond, and specific examples thereof include a (meth) acryloyl group and a vinyl group.

  The ultraviolet curable compound may be monofunctional or polyfunctional, but is preferably polyfunctional. In this case, the ultraviolet curable compound is preferably bifunctional or more, particularly preferably trifunctional or more, and more preferably tetrafunctional or more. Moreover, it is preferable that the said ultraviolet curable compound is 15 functional or less, It is especially preferable that it is 12 functional or less, Furthermore, it is preferable that it is 10 functional or less. When the ultraviolet curable compound is polyfunctional as described above, it is easy to control the adhesive force due to ultraviolet curing, and poor adhesion to the substrate due to increased volume shrinkage due to curing is less likely to occur.

  Specific examples of ultraviolet curable compounds include trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, dipentaerythritol poly Acrylate, or cyclic aliphatic skeleton-containing acrylate such as 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, dicyclopentadiene dimethoxy diacrylate, isobornyl acrylate, polyethylene glycol diacrylate, oligoester acrylate, Urethane acrylate oligomer, epoxy-modified acrylate, polyether Acrylate, acrylate compounds such as itaconic acid oligomer. These can also be used individually by 1 type and can also be used in combination of 2 or more type.

  The molecular weight of the ultraviolet curable compound is preferably 100 or more, and particularly preferably 300 or more. Moreover, it is preferable that the molecular weight of an ultraviolet curable compound is 30000 or less, and it is especially preferable that it is 10,000 or less. When the molecular weight of the ultraviolet curable compound is in the above range, the influence of material volatilization at the time of coating and drying can be suppressed while ensuring the film forming property.

  When the ultraviolet curable adhesive main component contains an ultraviolet non-curable polymer and an ultraviolet curable compound, the ratio of the ultraviolet curable compound to 100 parts by mass of the ultraviolet non-curable polymer (particularly acrylic polymer) is 50 masses. Part or more, preferably 70 parts by weight or more, and more preferably 85 parts by weight or more. Further, the ratio is preferably 300 parts by mass or less, particularly preferably 210 parts by mass or less, and further preferably 150 parts by mass or less. When the ratio is in the above range, good adhesive strength can be exhibited before curing, and the adhesive strength can be sufficiently reduced after curing.

(1-3) UV curable polymer The UV curable polymer is preferably a polymer having an UV curable group introduced therein. The polymer having the ultraviolet curable group introduced therein may be contained as it is in the pressure-sensitive adhesive layer, or at least a part thereof may have a crosslinked structure by performing a crosslinking reaction with a crosslinking agent.

  Examples of the polymer having an ultraviolet curable group introduced include, for example, a functional group-containing acrylic polymer having a functional group-containing monomer containing a functional group as a constituent, a substituent that reacts with the functional group, and an ultraviolet curable property. An acrylic polymer obtained by reacting a curable group-containing compound having a carbon-carbon double bond is mentioned.

  The functional group-containing acrylic polymer is preferably obtained by copolymerizing an acrylic monomer containing a functional group, an acrylic monomer not containing a functional group, and a monomer other than the acrylic monomer if desired. That is, the functional group-containing monomer is preferably an acrylic monomer containing a functional group.

  As the functional group of the acrylic monomer containing a functional group (functional group of the functional group-containing monomer), one capable of reacting with the substituent of the curable group-containing compound is selected. Examples of such functional groups include a hydroxy group, a carboxy group, an amino group, a substituted amino group, and an epoxy group. In addition, when the ultraviolet curable adhesive in this embodiment contains a crosslinking agent, the functional group-containing acrylic polymer contains a functional group-containing monomer having a functional group that reacts with the crosslinking agent as a constituent component. The functional group-containing monomer may also serve as a functional group-containing monomer having a functional group capable of reacting with the substituent of the curable group-containing compound.

  The acrylic monomer that does not contain a functional group preferably includes a (meth) acrylic acid alkyl ester monomer. Examples of the (meth) acrylic acid alkyl ester monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic acid n-. Pentyl, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate, myristyl (meth) acrylate, Examples include palmityl (meth) acrylate and stearyl (meth) acrylate. Among the (meth) acrylic acid alkyl ester monomers, those having 1 to 18 carbon atoms in the alkyl group are preferable, and those having 1 to 8 carbon atoms are particularly preferable. These may be used alone or in combination of two or more.

  In addition to the above (meth) acrylic acid alkyl ester monomer, acrylic monomers not containing functional groups include, for example, methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, ( Non-crosslinkable acrylamides such as (meth) acrylic acid esters containing alkenyl groups such as ethoxyethyl (meth) acrylate and aromatic rings such as phenyl (meth) acrylate, acrylamide and methacrylamide (Meth) acrylic acid ester having a non-crosslinking tertiary amino group such as N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate may be included.

  Examples of monomers other than acrylic monomers include olefins such as ethylene and norbornene, vinyl acetate, and styrene.

  In the functional group-containing acrylic polymer, the proportion of the mass of the structural portion derived from the functional group-containing monomer in the total mass of the functional group-containing acrylic polymer is preferably 0.1% by mass or more, particularly 1 mass. % Or more, and more preferably 3% by mass or more. In addition, the proportion is preferably 50% by mass or less, particularly preferably 40% by mass or less, and further preferably 30% by mass or less. Thereby, the amount of the curable group introduced by the curable group-containing compound (and the amount of reaction with the crosslinking agent) is adjusted to a desired amount, and the degree of crosslinking of the resulting pressure-sensitive adhesive layer can be controlled within a preferable range. it can.

  The functional group-containing acrylic polymer can be obtained by copolymerizing the above monomers by a conventional method. The polymerization mode of the functional group-containing acrylic polymer may be a random copolymer or a block copolymer.

  The curable group-containing compound has a substituent that reacts with the functional group of the functional group-containing acrylic polymer and an ultraviolet curable carbon-carbon double bond. Examples of the substituent that reacts with the functional group of the functional group-containing acrylic polymer include an isocyanate group, an epoxy group, and a carboxy group, and among them, an isocyanate group that is highly reactive with a hydroxy group is preferable.

  The curable group-containing compound preferably contains 1 to 5 ultraviolet curable carbon-carbon double bonds per molecule of the curable group-containing compound, and particularly preferably contains 1 to 2.

  Examples of such a curable group-containing compound include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1- (bisacryloyloxymethyl) ethyl. Isocyanate; acryloyl monoisocyanate compound obtained by reaction of diisocyanate compound or polyisocyanate compound and hydroxyethyl (meth) acrylate; obtained by reaction of diisocyanate compound or polyisocyanate compound, polyol compound and hydroxyethyl (meth) acrylate And acryloyl monoisocyanate compounds. A sclerosing | hardenable group containing compound can also be used individually by 1 type, and can also be used in combination of 2 or more type.

  The polymer in which the ultraviolet curable group is introduced has a curable group derived from the curable group-containing compound with respect to a functional group (functional group that reacts with a substituent of the curable group-containing compound) of the polymer. 20 mol% or more, preferably 35 mol% or more, more preferably 50 mol% or more. Moreover, it is preferable to contain 120 mol% or less, and it is preferable to contain especially 100 mol% or less. In addition, when a curable group containing compound is monofunctional, an upper limit will be 100 mol%, but when a curable group containing compound is polyfunctional, it may exceed 100 mol%. When the ratio of the curable group to the functional group is within the above range, the adhesiveness lowering property by ultraviolet irradiation becomes better.

  The weight average molecular weight (Mw) of the polymer into which the ultraviolet curable group is introduced is preferably 100,000 or more, and more preferably 300,000 or more. The weight average molecular weight is preferably 2 million or less, and more preferably 1.5 million or less. When the weight average molecular weight is in the above range, good adhesiveness can be exhibited, and the film forming property at the time of coating can be ensured satisfactorily.

(2) Crosslinking agent The adhesive composition which forms the ultraviolet curable adhesive in this embodiment may contain a crosslinking agent. As a crosslinking agent, the polyfunctional compound which has the reactivity with the functional group which the acrylic polymer mentioned above and the polymer in which the ultraviolet curable group was introduce | transduced can be used. Examples of such polyfunctional compounds include polyisocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts. And reactive phenol resins.

  Examples of the polyisocyanate 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 and hydrogenated diphenylmethane diisocyanate, and the like. , And their biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, from the viewpoint of reactivity with a functional group, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate is preferable.

  The content of the crosslinking agent is preferably 0.2 equivalents or more as a lower limit with respect to the functional group in the acrylic polymer or the polymer into which the ultraviolet curable group is introduced, and particularly preferably 0.25 equivalents or more. Preferably there is. Moreover, it is preferable that it is 0.8 equivalent or less as an upper limit, and it is especially preferable that it is 0.75 equivalent or less. When the content of the crosslinking agent is within the above range, the degree of crosslinking of the obtained pressure-sensitive adhesive layer can be controlled within a preferable range.

(3) Photopolymerization initiator The photopolymerization initiator contained in the pressure-sensitive adhesive composition in the present embodiment is cleaved by irradiation with light having a wavelength of 385 nm or has the maximum mass absorption coefficient of light in the wavelength region of 370 to 390 nm. The value is 200 ml / g · cm or more and 10,000 ml / g · cm or less. Here, the mass extinction coefficient in this specification shall be measured as 0.01 mass% acetonitrile solution, and specifically, it is measured by the method shown in the test example mentioned later.

  As described above, the maximum value of the mass absorption coefficient of light in the wavelength region of 370 to 390 nm is 200 ml / g · cm or more, preferably 500 ml / g · cm or more, particularly 1000 ml / g · cm or more. Preferably there is. The maximum value of the mass extinction coefficient is 10000 ml / g · cm or less, preferably 5000 ml / g · cm or less, and particularly preferably 2000 ml / g · cm or less. When the maximum value of the mass extinction coefficient of light in the wavelength region of 370 to 390 nm is in the above range, the photopolymerization initiator can be cleaved by irradiation with light of wavelength 385 nm, thereby generating radicals. .

  The lower limit of the mass extinction coefficient of light having a wavelength of 385 nm of the photopolymerization initiator is preferably 100 ml / g · cm or more, particularly preferably 200 ml / g · cm or more, and more preferably 300 ml / g · cm. It is preferably g · cm or more. As a result, the photopolymerization initiator is easily cleaved by irradiation with light having a wavelength of 385 nm, whereby radicals can be sufficiently generated.

  Examples of the photopolymerization initiator that satisfies the above physical properties include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone- 1, iodonium, (4-methylphenyl) [4- (2-methylpropyl) phenyl] -hexafluorophosphate (1-), oxyphenylacetic acid 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester, Oxyphenylacetic acid 2- (2-hydroxyethoxy) ethyl ester, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenyl-propane -1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy -2-methyl-1-propan-1-one and the like. Among these, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 which are easily cleaved by irradiation with light having a wavelength of 385 nm Is preferred. These photopolymerization initiators can be used singly or in combination of two or more.

  Content of the said photoinitiator in the adhesive composition in this embodiment is 100 mass parts of ultraviolet curable components (an ultraviolet curable compound and an ultraviolet curable polymer) in the said ultraviolet curable adhesive. 0.3 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 0.7 parts by mass or more. In addition, the content is preferably 5.0 parts by mass or less, particularly preferably 3.0 parts by mass or less, and further preferably 2.0 parts by mass or less. The photopolymerization initiator preferably has a relatively small content as described above, whereby it is difficult for the UV-curable adhesive to proceed even under a fluorescent lamp, and the adhesive sheet is stored under a fluorescent lamp. Even so, it is possible to stably exhibit good adhesive force to the adherend (workpiece). In addition, even when the photopolymerization initiator has a relatively small content as described above, the ultraviolet curable adhesive is sufficiently cured by irradiation with light having a wavelength of 385 nm in combination with the radical generator, Adhesive strength can be sufficiently reduced.

(4) Radical generator The radical generator contained in the pressure-sensitive adhesive composition in the present embodiment does not cleave when irradiated with light having a wavelength of 385 nm, and generates radicals by cleavage of the photopolymerization initiator. The maximum value of the mass absorption coefficient of light in the wavelength region of 370 to 390 nm is less than 200 ml / g · cm. The pressure-sensitive adhesive composition according to this embodiment contains such a radical generator, so that the curing of the UV-curable pressure-sensitive adhesive is difficult to proceed even under a fluorescent lamp, and the pressure-sensitive adhesive sheet has excellent storage stability under a fluorescent lamp. It will be a thing. On the other hand, when a light beam having a wavelength of 385 nm is irradiated, the photopolymerization initiator is cleaved to generate radicals, which are induced by the radicals, and the radical generator also generates radicals. It can be cured and the adhesive strength of the adhesive layer is sufficiently reduced. In addition, due to the above-described action of the radical generator, the irradiation time of the light can be shortened, thereby increasing the production efficiency.

  The maximum value of the mass absorption coefficient of light in the wavelength region of 370 to 390 nm of the radical generator is less than 200 ml / g · cm as described above, preferably 100 ml / g · cm or less, particularly preferably 70 ml. / G · cm or less. The lower limit is 0 ml / g · cm. As a result, the radical generator hardly generates radicals under a fluorescent lamp, and therefore the pressure-sensitive adhesive sheet has excellent storage stability under a fluorescent lamp.

  The lower limit of the mass extinction coefficient of the light having a wavelength of 365 nm of the radical generator is preferably 100 ml / g · cm or more, particularly preferably 150 ml / g · cm or more, and more preferably 200 ml / g. -It is preferable that it is cm or more. The upper limit of the mass extinction coefficient is preferably 10,000 ml / g · cm or less, particularly preferably 7000 ml / g · cm or less, and more preferably 6000 ml / g · cm or less.

  Examples of the radical generator satisfying the above physical properties include 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl. } -2-Methyl-propan-1-one, bis (2,4-cyclopentadienyl) bis [2,6-difluoro-3- (1-pyryl) phenyl] titanium, bis (2,4,6- And trimethylbenzoyl) -phenylphosphine oxide. Among these, 1-hydroxy-cyclohexyl-phenyl-ketone and 2-hydroxy-1- {4- [2- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl are less likely to generate radicals under fluorescent light. } -2-Methyl-propan-1-one is preferred. One of these radical generators can be used alone, or two or more thereof can be used in combination.

  The content of the radical generator in the pressure-sensitive adhesive composition in the present embodiment is based on 100 parts by mass of the ultraviolet curable component (ultraviolet curable compound / ultraviolet curable polymer) in the ultraviolet curable adhesive. The amount is preferably 0.8 parts by mass or more, particularly preferably 1.0 part by mass or more, and further preferably 2.0 parts by mass or more. Further, the content is preferably 7.0 parts by mass or less, particularly preferably 5.0 parts by mass or less, and further preferably 3.0 parts by mass or less. When the content of the radical generator is in the above range, the above-described operational effects are satisfactorily exhibited.

(5) Thickness The lower limit of the thickness of the pressure-sensitive adhesive layer in the present embodiment is preferably 3 μm or more, particularly preferably 4 μm or more, and more preferably 5 μm or more. Since the lower limit of the thickness of the pressure-sensitive adhesive layer is not less than the above, desired adhesive force can be effectively obtained. The thickness of the pressure-sensitive adhesive layer in the present embodiment is preferably 30 μm or less, particularly preferably 25 μm or less, and further preferably 20 μm or less. When the upper limit of the thickness of the pressure-sensitive adhesive layer is not more than the above, the ultraviolet curable pressure-sensitive adhesive is easily cured by appropriate irradiation with light having a wavelength of 385 nm.

2. Base Material The base material of the pressure-sensitive adhesive sheet according to the present embodiment can support the above-described pressure-sensitive adhesive layer, and can perform a desired operation on a work, particularly an optical member, to which the pressure-sensitive adhesive sheet is attached. If there is, it will not be specifically limited.

  It is preferable that the base material in this embodiment transmits a light beam having a wavelength of 385 nm. With this, the pressure-sensitive adhesive layer can be cured by irradiating the light beam having a wavelength of 385 nm from the base material side.

  From the above viewpoint, the base material in the present embodiment is preferably composed of a film (hereinafter referred to as “resin film”) whose main material is a resin-based material. Specific examples of resin films include polyethylene films such as low density polyethylene (LDPE) films, linear low density polyethylene (LLDPE) films, and high density polyethylene (HDPE) films, polypropylene films, polybutene films, polybutadiene films, and polymethylpentene films. Polyolefin films such as ethylene-norbornene copolymer film and norbornene resin film; ethylene-vinyl acetate copolymer film, ethylene- (meth) acrylic acid copolymer (EAA, EMAA) film, ethylene- (meth) acrylic Ethylene copolymer films such as acid ester copolymer films; Polyvinyl chloride films such as polyvinyl chloride films and vinyl chloride copolymer films; Polyethylene terephthalate fill , Polyester film such as polyethylene terephthalate and polybutylene terephthalate film; polyurethane film; polyimide film; polystyrene films; polycarbonate films; fluorine resin film; an acrylic film. Further, modified films such as these crosslinked films and ionomer films are also used. The substrate may be a film made of one of these, or may be a laminated film in which two or more of these are combined. Among these, an ethylene- (meth) acrylic acid copolymer (EAA, EMAA) film, a polyethylene terephthalate film, and the like are preferable from the viewpoints of strength, environmental safety, cost, and the like.

  The resin film can be subjected to a surface treatment by an oxidation method, a concavo-convex method, or a primer treatment on one side or both sides as desired for the purpose of improving the adhesion with the pressure-sensitive adhesive layer laminated on the surface. . Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, ultraviolet irradiation treatment, and the like. Examples include a thermal spraying method.

  Moreover, you may perform a peeling process by the peeling agent on the surface by which the adhesive layer in the said resin film is not laminated | stacked. Thereby, even when the pressure-sensitive adhesive sheet is used as a wound body without using a release film, the feeding can be performed satisfactorily.

  The base material may contain various additives such as a colorant, a flame retardant, a plasticizer, an antistatic agent, a lubricant, and a filler in the resin film.

  The thickness of the substrate is not particularly limited as long as a desired operation can be performed on the adherend to which the pressure-sensitive adhesive sheet is attached, particularly the optical member. Specifically, the thickness of the substrate is preferably 25 μm or more, and particularly preferably 50 μm or more. The thickness is preferably 200 μm or less, and particularly preferably 150 μm or less.

3. Release film A release film protects an adhesive layer until an adhesive sheet is used, and does not necessarily need to be. The configuration of the release film is arbitrary, and examples thereof include a plastic film having peelability with respect to the pressure-sensitive adhesive layer, and a film obtained by peeling the plastic film with a release agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. As the release agent, silicone-based, fluorine-based, long-chain alkyl-based, and the like can be used, and among these, a silicone-based material that is inexpensive and provides stable performance is preferable. Although there is no restriction | limiting in particular about the thickness of a peeling film, Usually, it is about 20-250 micrometers.

4). Manufacturing method of pressure-sensitive adhesive sheet In order to manufacture the pressure-sensitive adhesive sheet according to the present embodiment, the release surface of the release film (the surface having peelability; usually the surface subjected to the release treatment, but is not limited thereto. ) To form an adhesive layer. Specifically, a coating solution containing the pressure-sensitive adhesive composition described above and, if desired, a solvent is prepared, and a roll coater, knife coater, roll knife coater, air knife coater, die coater, bar coater, gravure coater, curtain The pressure-sensitive adhesive layer is formed by applying the coating onto the release surface of the release film using a coating machine such as a coater and drying it.

  Next, a base material is stacked on the exposed surface of the pressure-sensitive adhesive layer and pressure-bonded to obtain a pressure-sensitive adhesive sheet. If desired, the release film may be released from the pressure-sensitive adhesive layer. In addition, the pressure-sensitive adhesive layer may be formed by directly applying to the substrate instead of the release film.

5. Physical properties of the pressure-sensitive adhesive sheet The adhesive strength of the pressure-sensitive adhesive sheet according to this embodiment to the silicon mirror wafer before irradiation with light having a wavelength of 385 nm (sometimes referred to as “adhesive strength before irradiation” in this specification) is 8000 mN / It is preferably 25 mm or more, particularly preferably 10,000 mN / 25 mm or more, and further preferably 13000 mN / 25 mm or more. Thereby, it can suppress that unintended peeling arises during the operation | work about the workpiece | work to which the adhesive sheet was stuck. In addition, it can exhibit good adhesion to various materials and can be applied to a wide range of workpieces. On the other hand, the adhesive strength before irradiation is preferably 300,000 mN / 25 mm or less as an upper limit, particularly preferably 250,000 mN / 25 mm or less, and more preferably 200000 mN / 25 mm or less. Thereby, it becomes easy to reduce the adhesive force after irradiation with light having a wavelength of 385 nm to a preferred range. In addition, the adhesive force in this specification shall be measured by the 180 degree peeling test based on JIS Z0237: 2000 using a silicon mirror wafer as an adherend, and a specific measurement method is shown in a test example described later. Street.

  The adhesive strength of the pressure-sensitive adhesive sheet according to this embodiment to the silicon mirror wafer after irradiation with light having a wavelength of 385 nm (sometimes referred to as “post-irradiation pressure-sensitive adhesive force” in this specification) is 1000 mN / 25 mm or less as an upper limit. In particular, it is preferably 600 mN / 25 mm or less, and more preferably 300 mN / 25 mm or less. Thereby, an adhesive sheet can be easily peeled from a workpiece | work. On the other hand, the lower limit value of the post-irradiation adhesive strength is not particularly limited, but is usually preferably 20 mN / 25 mm or more, particularly preferably 30 mN / 25 mm or more, and more preferably 50 mN / 25 mm or more. preferable.

  The ratio of the adhesive strength after irradiation to the adhesive strength before irradiation (adhesive strength ratio) is preferably 15% or less, particularly preferably 10% or less, and further preferably 5% or less. Further, the adhesive force ratio is usually preferably 0.1% or more, particularly preferably 0.2% or more, and further preferably 0.5% or more. A good balance between the high adhesive force required during work on the work with the adhesive sheet affixed and the low adhesive force required during peeling from the work due to the adhesive force ratio being in the above range. It becomes.

The pressure-sensitive adhesive strength maintenance rate represented by the following formula of the pressure-sensitive adhesive sheet according to this embodiment is preferably 85% or more, and particularly preferably 90% or more. It can be said that the storage stability under a fluorescent lamp is excellent when the adhesive strength maintenance ratio is 85% or more. The upper limit of the adhesive strength maintenance rate is usually 100%.
Adhesive strength maintenance rate (%) = (adhesive strength before irradiation after storage under fluorescent light / adhesive strength before irradiation before storage under fluorescent light) × 100
The specific calculation method of the adhesive strength maintenance rate is as shown in the test examples described later.

6). How to use the pressure-sensitive adhesive sheet In order to use the pressure-sensitive adhesive sheet according to the present embodiment, the pressure-sensitive adhesive sheet is first attached to a work, and a desired work is performed on the work while handling the pressure-sensitive adhesive sheet in that state. As the workpiece, an optical member to be described later is preferable, but a silicon wafer, a semiconductor package, a glass wafer, or the like may be used as the workpiece. The desired work is not particularly limited. For example, the work is moved from one position to another position, the work peeling film is peeled from the work, the work is laminated on a desired object, or The work etc. which stick is mentioned.

  After performing a desired operation | work about a workpiece | work, the said adhesive sheet is peeled from a workpiece | work. At that time, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is irradiated with light having a wavelength of 385 nm to cure the UV-curable pressure-sensitive adhesive in the pressure-sensitive adhesive layer, thereby reducing the adhesive strength of the pressure-sensitive adhesive layer. Thereby, an adhesive sheet can be easily peeled from a workpiece | work. Irradiation with a light beam having a wavelength of 385 nm may be performed from the workpiece side as long as the workpiece transmits a light beam having a wavelength of 385 nm, but is usually preferably performed from the substrate side.

  Light with a wavelength of 385 nm is preferably irradiated using an ultraviolet irradiation device using an ultraviolet LED as a light source. The ultraviolet LED can keep the running cost low as compared with the conventional metal halide and high-pressure mercury lamp, and has a small heat generation amount, so that the irradiation object is less likely to be heated. Therefore, curling and deformation of the pressure-sensitive adhesive sheet and workpiece laminate by heating can be suppressed.

  When an ultraviolet LED is used as a light source, specifically, a light beam having a single emission peak having a maximum intensity in a range of 365 nm to 400 nm and a full width at half maximum of 5 nm to 30 nm is irradiated. It is preferable.

The irradiation amount of the light beam is preferably 15 mJ / cm ² or more in terms of integrated light amount when a single light source (a light source having a single emission peak with a full width at half maximum of 10 nm or less in its emission spectrum) is used. In particular, 20 mJ / cm ² or more is preferable. Further, when using an ordinary light source is not a single emission is preferably 150 mJ / cm ² or more in accumulated light quantity, in particular 200 mJ / cm ² or more.

  In the pressure-sensitive adhesive layer in the present embodiment, since the predetermined photopolymerization initiator and the radical generator are used in combination as described above, the irradiation time of the light can be made relatively short as described above. Production efficiency can be improved.

[Method of manufacturing optical products]
Next, a method for manufacturing an optical product according to an embodiment of the present invention using the above-described pressure-sensitive adhesive sheet will be described. Here, examples of the optical product include a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, and the like, and may be a touch panel. Further, the optical product may be a member constituting a part of the product as described above.

  As an optical member for manufacturing the optical product, for example, a glass plate, a plastic plate, and various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, antiglare layer, etc.) are provided on them. Anti-scattering film, polarizing plate (polarizing film), polarizer, retardation plate (retarding film), viewing angle compensation film, brightness enhancement film, contrast enhancement film, liquid crystal polymer film, diffusion film, transflective film Transparent conductive films, laminates thereof; display module (for example, liquid crystal (LCD) module, light emitting diode (LED) module, organic electroluminescence (organic EL) module, etc.), part of display module, display Examples include a laminate including a body module.

  First, the pressure-sensitive adhesive sheet according to this embodiment is attached to the optical member via the pressure-sensitive adhesive layer. And about an optical member with which the adhesive sheet was affixed, a desired operation | work is performed, handling the said adhesive sheet. The desired work is the same as the work for the workpiece described above.

  When the desired work is completed, the adhesive layer of the adhesive sheet affixed to the optical member is irradiated with a light beam having a wavelength of 385 nm to cure the UV-curable adhesive of the adhesive layer. Reduces adhesive strength. And an adhesive sheet is peeled from an optical member. Irradiation with a light beam having a wavelength of 385 nm is the same as the light beam irradiation with respect to the pressure-sensitive adhesive sheet affixed to the aforementioned workpiece. The pressure-sensitive adhesive sheet according to this embodiment can be easily peeled off because the pressure-sensitive adhesive strength is sufficiently reduced by irradiation with light having a wavelength of 385 nm. In addition, since the pressure-sensitive adhesive sheet according to the present embodiment is excellent in storage stability under a fluorescent lamp, even when the adhesive sheet is stored under a fluorescent lamp before use as described above, an adherend (optical member) is used. In contrast, it is possible to stably exhibit good adhesive strength. Thereby, an optical product can be manufactured stably.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, another layer may be interposed between the substrate and the pressure-sensitive adhesive layer, and another layer is laminated on the surface of the substrate opposite to the surface on the pressure-sensitive adhesive layer side. It may be.

  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 pressure-sensitive adhesive composition An acrylic polymer (non-UV curable polymer) obtained by copolymerizing 40 parts by mass of 2-ethylhexyl acrylate, 50 parts by mass of methyl acrylate, and 10 parts by mass of acrylic acid. Weight average molecular weight: 500,000, glass transition temperature Tg: −23 ° C.).

  100 parts by mass of the acrylic polymer as an ultraviolet curable adhesive main component (in terms of solid content; the same applies hereinafter) and 100 parts by mass of a 10-functional dipentaerythritol polyacrylate (weight average molecular weight: 1700) as an ultraviolet curable compound, and crosslinking 8 parts by mass of a composition containing trimethylolpropane-modified tolylene diisocyanate (TDI-TMP) as an agent (Tosoh Corp., Coronate L) and 2,4,6-trimethylbenzoyl-diphenyl-phos as a photopolymerization initiator 0.7 parts by mass of fin oxide (photopolymerization initiator (a1)) and 2.8 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (radical generator (b1)) as a radical generator are mixed, This was diluted with ethyl acetate, and this was used as a coating solution for the pressure-sensitive adhesive composition.

(2) Preparation of pressure-sensitive adhesive sheet The pressure-sensitive adhesive film was peeled onto the release-treated surface of a release film (SP-PET 381031 manufactured by Lintec Co., Ltd.) on one main surface of a polyethylene terephthalate film having a thickness of 38 μm. The coating solution of the agent composition was applied with a die coater and dried to form an adhesive layer having a thickness of 10 μm. And one surface of the base material which consists of a 140-micrometer-thick ethylene-methacrylic acid copolymer (EMAA) film is affixed with the surface at the side of the adhesive layer of the said laminated body, and consists of a base material and an adhesive layer. The pressure-sensitive adhesive sheet was obtained in a state where a release film was laminated on the surface of the pressure-sensitive adhesive layer opposite to the base material.

[Example 2]
As a photopolymerization initiator, 1.5 parts by mass of 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (photopolymerization initiator (a2)) is used as a radical generator. 2-Hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one (radical generator (b2)). A coating solution for the pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that 3 parts by mass was used. And the adhesive sheet was produced like Example 1 using the coating liquid of the obtained adhesive composition.

[Comparative Examples 1-4]
A coating solution for the pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the blending amounts of the photopolymerization initiator and the radical generator were changed as shown in Table 1. And the adhesive sheet was produced like Example 1 using the coating liquid of the obtained adhesive composition.

[Test Example 1] <Measurement of mass extinction coefficient>
Each of the photopolymerization initiator and the radical generator used in Examples and Comparative Examples was dissolved in acetonitrile to obtain a 0.01% by mass acetonitrile solution. About each of the obtained 0.01 mass% acetonitrile solution, the absorption spectrum was measured about the range (200 nm-800 nm) of ultraviolet light to visible light. As a measuring instrument, UV-3600 manufactured by Shimadzu Corporation was used. A mass extinction coefficient at a wavelength of 385 nm was determined from the obtained absorption spectrum (unit: ml / g · cm). Moreover, the maximum value of the mass extinction coefficient in the wavelength region of wavelengths of 370 to 390 nm was determined (unit: ml / g · cm). The results are shown in Table 2.

[Test Example 2] <Measurement of adhesive strength and adhesive strength ratio>
For the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples, after curing for 7 days in an environment of 23 ° C. and a relative humidity of 50%, each was cut to measure the adhesive strength of 200 mm in length and 25 mm in width. A sheet was obtained. The pressure-sensitive adhesive layer side of the obtained pressure-sensitive adhesive measurement sheet was attached to a silicon mirror wafer using a 2 kg roller to obtain a laminate composed of the silicon mirror wafer and the pressure-sensitive adhesive measurement sheet. The obtained laminate was left in an atmosphere of 23 ° C. and 50% relative humidity for 20 minutes, and this was used as an evaluation sample.

  The evaluation sample was peeled off 180 ° according to JIS Z0237: 2000 using an all-purpose tensile tester (Orientec Co., Ltd., TENSILON / UTM-4-100). The adhesive strength before irradiation was measured (unit: mN / 25 mm). Table 3 shows the measurement results of the adhesive strength before irradiation.

Moreover, with respect to the said evaluation sample, the ultraviolet-ray was irradiated from the surface by the side of the base material of the sheet | seat for adhesive force measurement, and the adhesive layer was hardened. This ultraviolet irradiation is performed using an ultraviolet LED as a light source (an energy ray including ultraviolet rays to be emitted has a single emission peak having a maximum intensity of 385 nm and a full width at half maximum of 10 nm in its emission spectrum). An apparatus (manufactured by Panasonic, UD40) was used, and the illuminance was 1.2 mW / cm ² and the integrated light quantity was 20 mJ / cm ² (measured by UVPF-A1 manufactured by Eye Graphics). About the evaluation sample after this ultraviolet irradiation, the peeling test on the same conditions as the peeling test for measuring said adhesive strength before irradiation was performed, and the adhesive strength after irradiation was measured (unit: mN / 25mm). Table 3 shows the measurement results of the adhesive strength after irradiation.

From the adhesive strength before irradiation and the adhesive strength after irradiation measured as described above, the ratio of the adhesive strength after irradiation to the adhesive strength before irradiation (adhesive strength ratio) was calculated. Based on this adhesive strength ratio, the following criteria were used to evaluate the reduction in adhesive strength due to ultraviolet irradiation. Table 3 shows the adhesive strength ratio and the evaluation results.
◯: Adhesive strength ratio is 3% or less, and is excellent in adhesive strength reduction due to ultraviolet irradiation.
X: The adhesive strength ratio exceeds 3%, and the adhesive strength is poorly reduced by ultraviolet irradiation.

[Test Example 3] <Evaluation of storage stability>
For the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples, after curing for 7 days in an environment of 23 ° C. and a relative humidity of 50%, each was cut to measure the adhesive strength of 200 mm in length and 25 mm in width. A sheet was obtained. The surface of the obtained adhesive force measurement sheet on the substrate side was irradiated with light from a fluorescent lamp (400 lx; UV cut type) disposed at a distance of 30 cm from the surface on the substrate side for one week.

Thereafter, the adhesive strength before irradiation was measured by the same operation as in Test Example 2 for the above adhesive strength measuring sheet. The adhesive strength maintenance rate (unit:%), which is the ratio of the pre-irradiation adhesive strength after storage obtained by measurement to the pre-irradiation adhesive strength before storage (pre-irradiation adhesive strength measured in Test Example 2), was calculated. . Based on this adhesive strength maintenance rate, storage stability was evaluated according to the following criteria. Table 3 shows the adhesive strength maintenance ratio and the evaluation results.
○: Adhesive strength maintenance rate is 90% or more, and excellent storage stability under fluorescent lamps.
X: The adhesive strength maintenance rate is less than 90%, and the storage stability under a fluorescent lamp is poor.

  As can be seen from Table 3, the pressure-sensitive adhesive sheets prepared in the examples are excellent in adhesive strength reduction due to irradiation with ultraviolet rays having a wavelength of 385 nm, and excellent in storage stability under a fluorescent lamp.

  The pressure-sensitive adhesive sheet according to the present invention is suitable for, for example, manufacturing an optical product by being affixed to an optical member and, after the desired operation is performed on the optical member in that state, being peeled from the optical member. Used.

Claims (10)

A substrate;
A pressure-sensitive adhesive layer made of an ultraviolet curable pressure-sensitive adhesive laminated on at least one surface side of the base material;
The UV curable adhesive is
(A) a photopolymerization initiator that is cleaved by irradiation with light having a wavelength of 385 nm;
(B) It is formed from a pressure-sensitive adhesive composition containing a radical generator that is not cleaved by irradiation with light having a wavelength of 385 nm and that generates radicals by cleaving the photopolymerization initiator. Adhesive sheet. A substrate;
A pressure-sensitive adhesive layer made of an ultraviolet curable pressure-sensitive adhesive laminated on at least one surface side of the base material;
The UV curable adhesive is
(A) a photopolymerization initiator having a maximum value of a mass extinction coefficient of light in a wavelength region of 370 to 390 nm of 200 ml / g · cm or more and 10,000 ml / g · cm or less;
(B) It is formed from a pressure-sensitive adhesive composition containing a radical generator having a maximum value of a mass extinction coefficient of light in a wavelength range of 370 to 390 nm and less than 200 ml / g · cm. Adhesive sheet. Content of the said photoinitiator in the said adhesive composition is 0.3 mass part or more and 5 mass parts or less with respect to 100 mass parts of ultraviolet curable components in the said ultraviolet curable adhesive,
Content of the said radical generator in the said adhesive composition is 0.8 mass part or more and 7.0 mass parts or less with respect to 100 mass parts of ultraviolet curable components in the said ultraviolet curable adhesive. The pressure sensitive adhesive sheet according to claim 1 or 2 characterized by things. The ultraviolet curable adhesive is
UV non-curable polymer,
The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, comprising an ultraviolet curable monomer and / or oligomer.   The pressure-sensitive adhesive sheet according to claim 4, wherein the ultraviolet non-curable polymer has a cross-linked structure via a cross-linking agent.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive force of the pressure-sensitive adhesive sheet before irradiation with light having a wavelength of 385 nm is 8000 mN / 25 mm or more and 300000 mN / 25 mm or less. .   The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive force of the pressure-sensitive adhesive sheet after irradiation with light having a wavelength of 385 nm is 1000 mN / 25 mm or less.   The ratio of the pressure-sensitive adhesive force of the pressure-sensitive adhesive sheet to the silicon mirror wafer after irradiation with light having a wavelength of 385 nm to the pressure-sensitive adhesive force of the pressure-sensitive adhesive sheet to the silicon mirror wafer before irradiation with a light beam having a wavelength of 385 nm is 0.1% or more and 15% or less. It is, The adhesive sheet as described in any one of Claims 1-7 characterized by the above-mentioned.   It is used for manufacture of an optical product, The adhesive sheet as described in any one of Claims 1-8 characterized by the above-mentioned. The step of sticking the pressure-sensitive adhesive sheet according to any one of claims 1 to 9 to an optical member via the pressure-sensitive adhesive layer;
A step of performing a desired operation on the optical member to which the adhesive sheet is attached;
Irradiating a light beam having a wavelength of 385 nm to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet affixed to the optical member, and reducing the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer;
And a step of peeling the pressure-sensitive adhesive sheet from the optical member.