JP6907922B2 - UV curable adhesives, cured products, and adhesive sheets - Google Patents

Description

The present invention relates to UV curable pressure-sensitive adhesives, cured products, and pressure-sensitive adhesive sheets.

In recent years, display devices such as touch panels have been used in digital information devices such as mobile phones, portable game machines, and car navigation systems. In-vehicle touch panels are installed in in-vehicle displays such as display audio and rear seat entertainment, in addition to car navigation, which is the main application. There are a resistance film method, a capacitance method, and an infrared method for an in-vehicle touch panel, and at present, two methods, a resistance film method and a capacitance method, are the mainstream.

Capacitive touch panels have excellent operability of display devices with multi-touch and gesture functions, and can be processed into curved surfaces and irregular shapes, giving a high degree of freedom in design. These features have been highly evaluated by automakers and auto parts makers who are strengthening their efforts to improve the design of automobiles, and it is expected that their adoption will continue to expand in the future.

When manufacturing a display device mounted on a capacitive touch panel, a transparent double-sided adhesive sheet (OCA) is used for the purpose of bonding the display device and the optical member or the optical members to each other. The use of OCA has the advantage of improving visibility, impact resistance and reliability. OCA used in general portable devices is required to have performance such as transparency, weather resistance, and metal corrosion prevention. For in-vehicle applications, higher moisture and heat resistance and heat resistance are required. Further, the film thickness of the OCA tends to be increased in order to improve the impact resistance and design of the device.

Patent Document 1 describes adding an antioxidant to a photocurable resin composition in order to improve storage stability. Further, Patent Document 1 also describes that, by adding a polyphenol-based antioxidant, the viscosity of a photocurable resin composition containing polyene and polythiol does not increase when stored at room temperature, and the stability is improved.

Patent Document 2 describes that a hindered phenolic antioxidant is added to an active energy ray-curable pressure-sensitive adhesive composition in order to improve the transparency and metal corrosiveness of the cured pressure-sensitive adhesive layer. Patent Document 2 also describes that the addition of a hindered phenolic antioxidant improves the transparency of the cured adhesive layer after the durability test and the corrosion resistance to the ITO film.

In Patent Document 3, a phosphorus-based antioxidant is added to a pressure-sensitive adhesive sheet-forming composition containing a rubber, a polymerizable monomer, a photopolymerization initiator, and a pressure-sensitive adhesive to improve the adhesion of the pressure-sensitive adhesive sheet. It is stated that it should be done.

Patent Document 4 describes bis (1,2,2,6,6-pentamethyl-4-piperidyl) decandioart as a light stabilizer and triphenylphosphine or bis (2,4-di-tert) as an antioxidant. -Butyl-6-methylphenyl) It is described that ethylphosphine is added.

Patent Document 5 describes that a benzotriazole-based compound and a hindered phenol-based antioxidant are added in order to improve heat-resistant yellowing of an adhesive layer made of an acrylic resin that does not substantially contain a carboxyl group. ing. It is also described that when used in combination with both a benzotriazole-based compound and a hindered phenol-based antioxidant, discoloration of the 25 μm adhesive layer was suppressed after a heat resistance test at 80 ° C.

Japanese Patent No. 5869916 International Publication No. 2014/156199 Japanese Unexamined Patent Publication No. 2016-135832 Japanese Patent No. 5994445 Japanese Unexamined Patent Publication No. 2012-201078

However, Patent Document 1 does not describe the stability of the cured product of the resin composition, and Patent Documents 2 and 3 do not describe the effect of heat-resistant yellowing. Further, Patent Documents 4 and 5 do not describe the heat-resistant stability of the light stabilizer at a high temperature of 100 ° C. or higher.

The subject of the present invention is a substantially solvent-free transparent ultraviolet curable adhesive, which is excellent in visibility and appearance retention because it does not become cloudy due to high temperature and high humidity, and at high temperature. It is an object of the present invention to provide a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having excellent yellowing resistance.

As a result of diligent studies, the present inventor has found that the above-mentioned problems can be solved by an ultraviolet curable pressure-sensitive adhesive that satisfies specific conditions, and has completed the present invention.

The disclosure provides the following items:
(Item 1)
It is a reaction product of (A) (a1) polyether polyol, (a2) aliphatic polyisocyanate, and (a3-1) hydroxyl group-containing mono (meth) acrylate or (a3-2) isocyanate group-containing mono (meth) acrylate. Polyurethane (meth) acrylate,
(B) Alkyl mono (meth) acrylate having 4 to 12 carbon atoms in the alkyl group,
(C) Cycloalkyl mono (meth) acrylate having 6 to 10 carbon atoms in the cycloalkyl group,
(D) Mono (meth) acrylate containing a primary hydroxyl group,
(E) One or more photopolymerization initiators selected from the group consisting of α-hydroxyalkylphenone-based photopolymerization initiators and acylphosphine oxide-based photopolymerization initiators.
(F) Hindered phenolic antioxidants, as well as
(G) Contains a thioether-based antioxidant,
The component (E) is 0.1 to 2% by mass and the component (F) is 0.1 to 2 with respect to the total mass of the component (A), the component (B), the component (C), and the component (D). The mass%, the component (G) is 0.1 to 2% by mass, and the tackifier resin (H) is 5% by mass or less.
The mass ratio ((F) / (G)) of the component (F) to the component (G) is 0.7 to 2.0.
(I) The content of the ultraviolet non-reactive solvent is less than 1% by mass.
UV curable adhesive.
(Item 2)
The ratios of the components (A), (B), (C) and (D) to the total mass are 20 to 60% by mass, 10 to 50% by mass, 10 to 50% by mass, and so on, respectively. The ultraviolet curable pressure-sensitive adhesive according to the above item, which is 20 to 60% by mass.
(Item 3)
The ultraviolet curable pressure-sensitive adhesive according to any one of the above items, wherein the weight average molecular weight of the component (A) is 10,000 to 90,000.
(Item 4)
The ultraviolet curable pressure-sensitive adhesive according to any one of the above items, wherein the component (E) is 1-hydroxycyclohexylphenyl ketone and / or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.
(Item 5)
The ultraviolet curable pressure-sensitive adhesive according to any one of the above items, wherein the component (F) is a semi-hindered phenolic antioxidant.
(Item 6)
The above item, wherein the component (H) is one or more selected from the group consisting of a rosin derivative, a rosin and a hydrogenated resin of a rosin derivative, a hydrogenated resin of a terpenphenol resin, and a hydrogenated resin of a petroleum resin. The ultraviolet curable pressure-sensitive adhesive according to any one of the above.
(Item 7)
A cured product of the ultraviolet curable adhesive according to any one of the above items.
(Item 8)
An adhesive sheet using the cured product of the above item as an adhesive layer.

Since the ultraviolet curable pressure-sensitive adhesive of the present invention is transparent and substantially solvent-free, the solvent removal step can be omitted when producing the pressure-sensitive adhesive sheet. Further, since the adhesive layer (cured product) made of the composition does not become cloudy due to high temperature and high humidity, it is excellent in visibility and appearance retention, and exhibits excellent yellowing resistance at high temperature. In addition, the adhesive layer is colorless and transparent, has good removability, and has excellent holding power after heat treatment.

The ultraviolet curable pressure-sensitive adhesive of the present invention is suitable for optical applications (for example, a multi-layered display panel in a digital display device). Further, as described above, it is excellent in visibility and appearance retention without becoming cloudy due to high temperature and high humidity, and also has good yellowing resistance at high temperature, so that it exhibits excellent durability in in-vehicle display applications. can.

(1. UV curable adhesive)
It is a reaction product of (A) (a1) polyether polyol, (a2) aliphatic polyisocyanate, and (a3-1) hydroxyl group-containing mono (meth) acrylate or (a3-2) isocyanate group-containing mono (meth) acrylate. Polyurethane (meth) acrylate,
(B) Alkyl mono (meth) acrylate having 4 to 12 carbon atoms in the alkyl group,
(C) Cycloalkyl mono (meth) acrylate having 6 to 10 carbon atoms in the cycloalkyl group,
(D) Mono (meth) acrylate containing a primary hydroxyl group,
(E) One or more photopolymerization initiators selected from the group consisting of α-hydroxyalkylphenone-based photopolymerization initiators and acylphosphine oxide-based photopolymerization initiators.
(F) Hindered phenolic antioxidants, as well as
(G) Contains a thioether-based antioxidant,
The component (E) is 0.1 to 2% by mass and the component (F) is 0.1 to 2 with respect to the total mass of the component (A), the component (B), the component (C), and the component (D). The mass%, the component (G) is 0.1 to 2% by mass, and the tackifier resin (H) is 5% by mass or less.
The mass ratio ((F) / (G)) of the component (F) to the component (G) is 0.7 to 2.0.
(I) The content of the ultraviolet non-reactive solvent is less than 1% by mass.
Provided is an ultraviolet curable pressure-sensitive adhesive.

(A) Polyurethane (meth) acrylate (also referred to as component (A))
The component (A) reacts with (a1) polyether polyol, (a2) aliphatic polyisocyanate, and (a3-1) hydroxyl group-containing mono (meth) acrylate or (a3-2) isocyanate group-containing mono (meth) acrylate. It is obtained by letting it.

(A1) Polyether polyol (also referred to as (a1) component)
As the component (a1), various known polyether polyols can be used without particular limitation. (A1) Two or more kinds of components can be used in combination. Examples of the component (a1) include polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like. Commercially available products of the component (a1) are ADEKA polyether polyol 1000, ADEKA polyether polyol 2000, ADEKA polyether polyol 3000 (all manufactured by ADEKA Corporation), and PTMG1000 and PTMG2000 (all manufactured by Mitsubishi Chemical Corporation). Etc. are exemplified. The component (a1) is preferably polypropylene glycol in terms of the viscosity of the pressure-sensitive adhesive composition.

The physical properties of the component (a1) are not particularly limited, but the upper limit of the number average molecular weight of the component (a1) (polystyrene conversion value by gel permeation chromatography method; the same applies hereinafter) is 4000, 3500, 3000, 2500, 2000, 1500, 1000, 900, 800 and the like are exemplified, and the lower limit is 3500, 3000, 2500, 2000, 1500, 1000, 900, 800, 700 and the like. The range of the number average molecular weight can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, the number average molecular weight of the component (a1) is preferably 700 to 4000 from the viewpoint of high temperature holding power.

(A1) The upper limit of the weight average molecular weight of the component (polystyrene conversion value by gel permeation chromatography method; the same applies hereinafter) is exemplified by 5000, 4500, 4000, 3500, 3000, 2500, 2000, 1500, etc., and the lower limit is Examples thereof include 4500, 4000, 3500, 3000, 2500, 2000, 1500, 1000 and the like. The range of the weight average molecular weight can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, the weight average molecular weight of the component (a1) is preferably 1000 to 5000.

The average number of hydroxyl groups of the component (a1) is also not particularly limited, but the upper limit thereof is exemplified by 3, 2.5, 2 or the like, and the lower limit thereof is exemplified by 2.5, 2, 1.5 or the like. The range of the average number of hydroxyl groups of the component (a1) can be appropriately set (for example, selected from the above upper and lower limit values). In one embodiment, the average number of hydroxyl groups of the component (a1) is preferably about 1.5 to 3 from the viewpoint of adhesive strength.

(A2) Aliphatic polyisocyanate (also referred to as (a2) component)
As the component (a2), various known aliphatic polyisocyanates can be used without particular limitation. (A2) Two or more kinds of components can be used in combination. Examples of the component (a2) include acyclic aliphatic polyisocyanates and alicyclic polyisocyanates.
Examples of the acyclic aliphatic polyisocyanate include hexamethylene diisocyanate and trimethylhexamethylene diisocyanate.
Examples of the alicyclic polyisocyanate include dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,4-cyclohexanediisocyanate, hydrogenated xylene diisocyanate, and hydrogenated tolylene diisocyanate.

The number of isocyanate groups contained in the component (a2) is not particularly limited, but is preferably about 2 to 3 from the viewpoint of adhesive strength.

The number of carbon atoms in the aliphatic portion of the component (a2) is also not particularly limited, but the upper limit thereof is exemplified by 12, 11, 10, 9, 7 and the like, and the lower limit is exemplified by 11, 10, 9, 7, 6 and the like. Will be done. The range of the carbon number of the aliphatic portion of the component (a2) can be appropriately set (for example, selected from the above upper and lower limit values). In one embodiment, the number of carbon atoms in the aliphatic portion of the component (a2) is preferably about 6 to 12 from the viewpoint of adhesive strength and high temperature holding power.

(A3-1) Hydroxy group-containing mono (meth) acrylate (also referred to as (a3-1) component)
As the component (a3-1), various known hydroxyl group-containing mono (meth) acrylates can be used without particular limitation. Two or more kinds of the components (a3-1) can be used in combination.
Examples of the component (a3-1) include hydroxyl group-containing alkyl mono (meth) acrylates.
Examples of the hydroxyl group-containing alkyl mono (meth) acrylate include a hydroxyl group-containing linear alkyl mono (meth) acrylate.
The hydroxyl group-containing linear alkyl mono (meth) acrylate is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-. Examples thereof include hydroxybutyl (meth) acrylate and 6-hydroxyhexyl acrylate.
Among these, a hydroxyl group-containing mono (meth) acrylate having a total carbon number of 5 to 10 is preferable, and 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are particularly preferable in terms of durability and low-temperature flexibility. ..

In the present disclosure, "(meth) acrylate" means "at least one selected from the group consisting of acrylates and methacrylates". "(Meta) acrylic" means "at least one selected from the group consisting of acrylics and methacryl". "(Meta) acryloyl" means "at least one selected from the group consisting of acryloyl and methacryloyl".

(A3-2) Isocyanate group-containing mono (meth) acrylate (also referred to as (a3-2) component)
As the component (a3-2), various known isocyanate group-containing mono (meth) acrylates can be used without particular limitation. (A3-2) Two or more kinds of components can be used in combination. Examples of the component (a3-2) include 2-isocyanatoethyl (meth) acrylate and 1,1- (bis (meth) acryloyloxymethyl) ethyl isocyanate.

The method for producing the component (A) is not particularly limited, and various known methods for producing a polyurethane (meth) acrylate can be adopted. Hereinafter, the component (A) obtained when the component (a3-1) is used (hereinafter, the component (A1)) and the component (A) obtained when the component (a3-2) is used (hereinafter, the component (A1)). A2) component) will be described. As the component (A), the component (A1) and the component (A2) can be used in combination.

As the component (A1), the component (a1) and the component (a2) are reacted to once produce an isocyanate group-terminated urethane prepolymer (also referred to as a component (A1')), and then the component (A1') and the component (a3-) are produced. 1) Obtained by reacting the components. The reaction temperature and reaction time are not particularly limited, and are preferably about 70 to 85 ° C., preferably about 1 to 5 hours. Both the component (A1) and the component (A2) may be produced in the absence of a solvent, but may also be produced in the presence of the component (B) described later.

The usage ratio of the component (a1) and the component (a2) is not particularly limited, but the number of moles of the isocyanate group of the component (a2) (NCO _(a2) ) and the number of moles of the hydroxyl group of the component (a1) (OH _{(a1)). )} ) The upper limit of the ratio (NCO _(a2) / OH _(a1) ) is 2, 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1 .2, 1.1, 1.05, etc. are exemplified, and the lower limit is 1.9, 1.8, 1.7, 1.6, 1.5, 1.4, 1.3, 1.2, 1 .1, 1.05, 1.01 and the like are exemplified. The range of (NCO _(a2) / OH _(a1) ) can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, about 1.01 to 2 is preferable from the viewpoint of molecular weight control.

The ratio of the (A1') component to the (a3-1) component is also not particularly limited, but the number of moles of the former isocyanate group (NCO _(A1') ) and the number of moles of the latter hydroxyl group (OH _{(a3-1)) are not particularly limited.} ) And the upper limit of _{(NCO (A1')} / OH _{(a3-1)) is 1,0.9,0.8,0.7,0.6,0.5,0.4,0.3} Etc. are exemplified, and the lower limit is 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.25 and the like. The range of (NCO _(A1') / OH _(a3-1) ) can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, about 0.25 to 1 is preferable from the viewpoint of ultraviolet curability.

The component (A2) is prepared by reacting the component (a1) with the component (a2) to obtain a hydroxyl-terminated polyurethane (hereinafter, the component (A2')), and then the component (A2') and the component (a3-2). You just have to react. The reaction temperature and reaction time are the same as those described in the item of (A1) component.

The usage ratio of the component (a1) and the component (a2) is not particularly limited, but _{the upper limit of (NCO (a2)} / OH _(a1) ) is 0.99, 0.9, 0.8, 0.7, 0.6, 0.55 and the like are exemplified, and the lower limit is 0.95, 0.8, 0.7, 0.6, 0.5 and the like. The range of (NCO _(a2) / OH _(a1) ) can be set as appropriate (for example, by selecting from the above upper and lower limit values). _{In one embodiment, (NCO (a2)} / OH _(a1) ) is preferably about 0.50 to 0.99 from the viewpoint of molecular weight control.

The ratio of the component (A2') to the component (a3-2) is also not particularly limited, but the number of moles of the isocyanate group of the component (a3-2) (NCO _(a3-2) ) and the mole of the hydroxyl group of the component (A2') The upper limit of the ratio (NCO _(a3-2) / OH _(A2') ) to the number (OH _(A2') ) is 1,0.9, 0.8, 0.7, 0.6, 0.55, etc. Is exemplified, and the lower limit is 0.95, 0.8, 0.7, 0.6, 0.5 and the like. The range of (NCO _(a3-2) / OH _(A2') ) can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, (NCO _(a3-2) / OH _(A2') ) is preferably about 0.5 to 1 from the viewpoint of ultraviolet curability.

The average number of (meth) acryloyl groups in the component (A) is not particularly limited, but the upper limit thereof is exemplified by 4, 3.5, 3, 2.5, 2.2, 2, etc., and the lower limit is 3. .5, 3, 2.5, 2.2, 2, 1.8, 1.5 and the like are exemplified. The range of the average number of (meth) acryloyl groups in the component (A) can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, it is preferably about 1.5 to 4, more preferably about 2 to 4, and even more preferably about 1.8 to 2.2.

In the present disclosure, the "average number of (meth) acryloyl groups in the component (A)" is the average number of (meth) acryloyl groups present in one molecule of the component (A), and is (A). ) The total number of (meth) acryloyl groups present in the component is divided by the total number of molecules of the component (A). The average number can be calculated based on the amount of substance of each component and the like.

The physical properties of the component (A) are not particularly limited, but the upper limit of the weight average molecular weight (polystyrene conversion value by gel permeation chromatography method; the same applies hereinafter) is 90,000, 80,000, 70,000, 60,000. , 58,000, 55,000, 50,000, 40,000, 30,000, 20,000, 15,000, etc., and the lower limit is 85,000, 80,000, 70,000, 60,000. , 58,000, 55,000, 50,000, 40,000, 30,000, 20,000, 10,000 and the like. The range of the weight average molecular weight of the component (A) can be appropriately set (for example, selected from the above upper and lower limit values). In one embodiment, the weight average molecular weight of the component (A) is preferably 10,000 to 90,000 from the viewpoint of adhesive strength and high temperature holding power.

The number of Gardner colors of the component (A) is not particularly limited, but is preferably 1 or less.

The upper limit of the content of the component (A) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) is 60, 50, 49, 45, 40, 35, 25, 21 mass. % And the like are exemplified, and the lower limit is 49, 45, 40, 35, 25, 21, 20% by mass and the like. The range of the content can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, the ratio of the component (A) to the total mass of the component (A), the component (B), the component (C) and the component (D) from the viewpoint of curability and adhesive strength and the handleability of the pressure-sensitive adhesive. Is preferably 20 to 60% by mass, more preferably 20 to 50% by mass, and even more preferably 20 to 45% by mass.

(B) Alkyl mono (meth) acrylate having 4 to 12 carbon atoms in the alkyl group (also referred to as component (B))
As the component (B), an alkyl mono (meth) acrylate having an alkyl group having 4 to 12 carbon atoms can be used without particular limitation. Two or more kinds of the component (B) can be used together. Examples of the component (B) include linear alkyl mono (meth) acrylate and branched alkyl mono (meth) acrylate.
The linear alkyl mono (meth) acrylate having 4 to 12 carbon atoms of the alkyl group is n-butyl acrylate, n-octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, and undecyl (meth) acrylate. , Lauryl (meth) acrylate and the like are exemplified.
Examples of the branched alkyl mono (meth) acrylate having 4 to 12 carbon atoms of the alkyl group include isobutyl acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, and isodecyl (meth) acrylate. Will be done.

The upper limit of the number of carbon atoms of the alkyl group of the component (B) is 12, 11, 10, 9 and the like, and the lower limit is 11, 10, 9, 8 and the like. The range of carbon atoms of the alkyl group of the component (B) can be appropriately set (for example, selected from the above upper and lower limit values). In one embodiment, the alkyl group of the component (B) preferably has 8 to 12 carbon atoms from the viewpoint of adhesive strength and viscosity of the adhesive composition.

The upper limit of the content of the component (B) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) is 50, 45, 40, 35, 30, 25, 20, 15 mass. % And the like are exemplified, and the lower limit is 45, 40, 35, 30, 25, 20, 15, 10% by mass and the like. The range of the content can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, from the viewpoint of handleability and adhesive strength of the cured product, the content of the component (B) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) is determined. It is preferably 10 to 50% by mass, more preferably 20 to 40% by mass.

(C) Cycloalkyl mono (meth) acrylate having 6 to 10 carbon atoms in the cycloalkyl group (also referred to as the (C) component)
As the component (C), a cycloalkyl mono (meth) acrylate having a cycloalkyl group having 6 to 10 carbon atoms can be used without particular limitation. Examples of the component (C) include monocyclic alkyl mono (meth) acrylate and crosslinked ring alkyl mono (meth) acrylate.
Examples of the monocyclic alkyl mono (meth) acrylate include cyclohexyl (meth) acrylate and 4-t-butylcyclohexyl (meth) acrylate.
Examples of the crosslinked ring alkyl mono (meth) acrylate include isobornyl (meth) acrylate and dicyclopentanyl (meth) acrylicate. In the present disclosure, the "crosslinked ring" means a ring having a structure in which two or more carbons of the same ring which are not adjacent to each other are connected to each other.

The upper limit of the number of carbon atoms of the alkyl group of the component (C) is 10, 9, 8, 7 and the like, and the lower limit is 9, 8, 7, 6 and the like. The range of carbon atoms of the alkyl group of the component (C) can be appropriately set (for example, selected from the above upper and lower limit values). In one embodiment, the alkyl group of the component (C) preferably has 6 to 10 carbon atoms from the viewpoint of adhesive strength.

The upper limit of the content of the component (C) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) is 50, 45, 40, 35, 30, 25, 20, 15 mass. % And the like are exemplified, and the lower limit is 45, 40, 35, 30, 25, 20, 15, 10% by mass and the like. The range of the content can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, from the viewpoint of adhesive strength, high temperature holding power, and handleability of the pressure-sensitive adhesive, the component (C) with respect to the total mass of the component (A), the component (B), the component (C), and the component (D). The content of is preferably 10 to 50% by mass, more preferably 10 to 30% by mass.

(D) Mono (meth) acrylate containing a primary hydroxyl group (also referred to as component (D))
As the component (D), various known primary hydroxyl group-containing mono (meth) acrylates can be used without particular limitation. Two or more kinds of the component (D) can be used together. Examples of the component (D) include a primary hydroxyl group-containing acyclic mono (meth) acrylate and a primary hydroxyl group-containing cyclic mono (meth) acrylate.

In the present disclosure, the "acyclic mono (meth) acrylate" is a mono (meth) acrylate that does not contain a cyclic structure in the molecule. Examples of the primary hydroxyl group-containing acyclic mono (meth) acrylate include a primary hydroxyl group-containing linear alkyl mono (meth) acrylate and a primary hydroxyl group-containing branched alkyl mono (meth) acrylate. Examples of the primary hydroxyl group-containing linear alkyl mono (meth) acrylate include 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

In the present disclosure, the "cyclic mono (meth) acrylate" is a mono (meth) acrylate having a cyclic structure in the molecule. Examples of the "cyclic mono (meth) acrylate" include cyclohexanedimethanol mono (meth) acrylate.

The number of primary hydroxyl groups contained in the component (D) is not particularly limited, but is preferably about 1 to 2 from the viewpoint of moisture and heat resistance.

The total carbon number of the component (D) is not particularly limited, but is preferably about 5 to 10 from the viewpoint of adhesive strength.

The upper limit of the content of the component (D) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) is 60, 55, 50, 45, 40, 35, 30, 25, 21% by mass and the like are exemplified, and the lower limit is 55, 50, 45, 40, 35, 30, 25, 21, 20% by mass and the like. The range of the content can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, from the viewpoint of curability and durability of the cured product, the content of the component (D) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) is determined. 20 to 60% by mass is preferable, 21 to 60% by mass is more preferable, and 21 to 40% by mass is further preferable.

(E) Photopolymerization Initiator (also referred to as (E) component)
The component (E) is one selected from the group consisting of an α-hydroxyalkylphenone-based photopolymerization initiator (also referred to as (E1) component) and an acylphosphine oxide-based photopolymerization initiator (also referred to as (E2) component). That is all. Two or more kinds of the component (E1) and the component (E2) may be used in combination. Further, the component (E1) and the component (E2) may be used in combination.

(E1) As the α-hydroxyalkylphenone-based photopolymerization initiator (E1) component, various known components can be used without particular limitation. In the present disclosure, the "α-hydroxyalkylphenone-based photopolymerization initiator" is a photopolymerization initiator having an α-hydroxyalkylphenone structure. The component (E1) is 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-. Examples thereof include methyl-1-propan-1-one, 2-hydroxy-1-{4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2-methylpropan-1-one. ..

(E2) As the acylphosphine oxide-based photopolymerization initiator (E2) component, various known components can be used without particular limitation. In the present disclosure, the "acylphosphine oxide-based photopolymerization initiator" is a photopolymerization initiator having an acylphosphine oxide structure. Examples of the component (E2) include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and the like.

Among the components (E1) and (E2), 1-hydroxycyclohexylphenyl ketone and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide are preferable from the viewpoint of yellowing resistance at high temperature.

Examples of the upper limit of the content of the component (E) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) are 2, 1.5, 1, 0.5% by mass and the like. The lower limit is, for example, 1.5, 1, 0.5, 0.1% by mass, and the like. The range of the content can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, from the viewpoint of curability of the pressure-sensitive adhesive and heat-resistant yellowing at high temperature, the component (E) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) The content is preferably 0.1 to 2% by mass, more preferably 0.1 to 1% by mass, still more preferably 0.1 to 0.5% by mass.

(F) Hindered phenolic antioxidant (also referred to as (F) component)
In the present disclosure, the "hindard phenolic antioxidant" refers to an antioxidant having the following hindered phenol structure (also referred to as (F1) component) and an antioxidant having the following semi-hindered phenol structure ((F2) component). Also referred to), it means at least one selected from the group consisting of the following antioxidants having a less hindered phenol structure (also referred to as (F3) component). The components (F1) to (F3) may be used alone or in combination of two or more.

構造を有する酸化防止剤を意味する。 In the present disclosure, the antioxidant (F1) having a hindered phenol structure is represented by the following general formula (1).

It means an antioxidant having a structure.

Antioxidants having a hindered phenol structure are tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol (Irganox 1010 manufactured by BASF), 3- (3,5). Stearyl propionate (-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox 1076, manufactured by BASF), octyl-3,5-di-tert-butyl-4-hydroxy-hydropyronic acid (Irganox 1135, manufactured by BASF), Examples thereof include 2,4,6-tris (3', 5'-di-tert-butyl-4'-hydroxybenzyl) mecitylene (Irganox 1330 manufactured by BASF).

構造を有する酸化防止剤を意味する。 In the present disclosure, the antioxidant (F2) having a semi-hindered phenol structure is represented by the following general formula (2).

It means an antioxidant having a structure.

Antioxidants with a semi-hindered phenolic structure are 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-Tetraoxaspiro [5,5] Undecane (Adecastab AO-80 manufactured by Adeca), Ethylenebis (oxyethylene) bis [3- (5-tert-butyl-hydroxy-m-) Trill) propionate] (Irganox 245 manufactured by BASF), triethylene glycol bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] (Adecastab AO-70 manufactured by Adeca) and the like are examples. Will be done.

構造を有する酸化防止剤を意味する。 In the present disclosure, the antioxidant (F3) having a less hindered phenol structure is represented by the following general formula (3).

It means an antioxidant having a structure.

Antioxidants having a less hindered phenolic structure are 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane (Adeka Stub AO-30 manufactured by Adeka Corporation), 4, Examples thereof include 4'-butylidenebis (3-methyl-6-tert-butylphenol) (ADEKA STAB AO-40 manufactured by Adeka Corporation).

Conventionally, when an antioxidant having a hindered phenol structure is used, in order to achieve a desired effect, it may be necessary to require a component represented by the above general formula (1). However, surprisingly, in the present invention, even if the component represented by the above general formula (1) is not essential, a desired effect can be obtained by using only an antioxidant having a semi-hindered phenol structure represented by the general formula (2). It became clear that Even more surprisingly, it was revealed that the desired effect can be achieved even when only the antioxidant having the less hindered phenol structure represented by the general formula (3) is used.

Examples of the upper limit of the content of the component (F) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) are 2, 1.5, 1, 0.5% by mass and the like. The lower limit is, for example, 1.5, 1, 0.5, 0.1% by mass, and the like. The range of the content can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, the content of the component (F) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) is 0.1 to 2 from the viewpoint of heat-resistant yellowing. It is preferably 0.1% by mass, more preferably 0.1 to 1% by mass.

(G) Thioether-based antioxidant (also referred to as (G) component)
In the present disclosure, the "thioether-based antioxidant" means an antioxidant having a thioether structure, and can be used without particular limitation. Two or more kinds of the component (G) may be used in combination.

Examples of the thioether-based antioxidant include 3-alkylthiopropionic acid or an ester thereof, dimerized thioether of a thiocarboxylic acid alkyl ester, dialkyl sulfide and the like.

The 3-alkylthiopropionic acid or its ester is 3-laurylthiopropionic acid, methyl 3-laurylthiopropionic acid, (3-octylthiopropionic acid) pentaerythritol tetraester, (3-decylthiopropionic acid) pentaerythritol tetraester. , (3-laurylthiopropionic acid) pentaerythritol tetraester, (3-oleylthiopropionic acid) pentaerythritol tetraester, (3-stearylthiopropionic acid) pentaerythritol tetraester, (3-laurylthiopropionic acid) -4 , 4'-thiodi (3-methyl-5-tert-butyl-4-phenol) ester and the like are exemplified.

The dimerized thioethers of thiocarboxylic acid alkyl esters are dioctylthiodipropionate, didecylthiodipropionate, dilaurylthiodipropionate, dimyristylthiodipropionate, distearylthiodipropionate, and laurylstearylthiodipropionate. , Distearyl-β, β'-thiodibutyrate and the like.

Examples of the dialkyl sulfide include dimethyl sulfide, methyl dodecyl sulfide, dilauryl sulfide, and distearyl sulfide.

Examples of other thioether-based antioxidants include 2,4-bis (octylthiomethyl) -o-cresol and 2,4-bis (dodecylthiomethyl) -o-cresol.

Commercially available products of component (G) are dioctadecyl-3,3'-thiodipropionate ("DSTP" Yoshitomi "manufactured by Mitsubishi Chemical Co., Ltd.)" and dilauryl-3,3'-thiodipropionate (Mitsubishi Chemical Co., Ltd.). "DLTP" Yoshitomi "), ditridecyl-3,3'-thiodipropionate (Adeka Stub AO-503), distearyl-3,3'-thiodipropionate, 4,6-bis (Dodecylthiomethyl) -O-cresol (Irganox1726, BASF), 2,2'-thiodiethylbis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (Irganox1035, BASF) ) Etc. are exemplified.

Examples of the upper limit of the content of the component (G) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) are 2, 1.5, 1, 0.5% by mass and the like. The lower limit is, for example, 1.5, 1, 0.5, 0.1% by mass, and the like. The range of the content of the component (G) can be appropriately set (for example, selected from the above upper and lower limit values). In one embodiment, the content of the component (G) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) is 0.1 to 2 from the viewpoint of heat-resistant yellowing. It is preferably by mass, more preferably 0.1 to 1% by mass.

The upper limit of the mass ratio ((F) / (G)) of the content of the component (F) to the content of the component (G) in the pressure-sensitive adhesive is 2.0, 1.5, 1.0, 0.8 and the like are exemplified, and the lower limit is 1.5, 1.0, 0.7 and the like. The range ((F) / (G)) can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, the mass ratio ((F) / (G)) is preferably 0.7 to 2.0, more preferably 1.0 to 1.5, from the viewpoint of heat-resistant yellowing.

(H) Adhesive-imparting resin (also referred to as (H) component)
The component (H) is an optional component that can be used for the purpose of improving adhesive strength and flexibility, and examples thereof include a rosin derivative and a hydrogenated resin. Examples of the hydrogenated resin include hydrogenated resins of rosin and rosin derivatives, hydrogenated resins of terpenephenol resins, and hydrogenated resins of petroleum resins.

The upper limit of the content of the component (H) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) is exemplified by 5, 4, 3, 2, 1% by mass and the like. The lower limit is exemplified by 4, 3, 2, 1, 0% by mass and the like. The range of the content can be set as appropriate (for example, by selecting from the above upper and lower limit values). In one embodiment, from the viewpoint of high temperature holding power, the content of the component (H) with respect to the total mass of the component (A), the component (B), the component (C) and the component (D) is preferably 5% by mass or less. ..

(I) Ultraviolet non-reactive solvent (also referred to as (I) component)
In the present disclosure, the "ultraviolet non-reactive solvent" means a solvent that does not react (polymerize) even when irradiated with ultraviolet rays.

Examples of the ultraviolet non-reactive solvent include ethyl acetate, butyl acetate, toluene, xylene, methanol, ethanol, propanol, butanol, acetone, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, ethyl cellosolve, propylene glycol monomethyl ether, diacetone alcohol and the like. NS.

The content of the ultraviolet non-reactive solvent contained in the pressure-sensitive adhesive is preferably less than 1% by mass, more preferably less than 0.1% by mass, still more preferably less than 0.01% by mass, and most preferably 0% by mass. .. The ultraviolet non-reactive solvent contained in the pressure-sensitive adhesive may be derived from each raw material of the pressure-sensitive adhesive.

In one embodiment, the ratio of the component (A), the component (B), the component (C) and the component (D) in the pressure-sensitive adhesive according to the present invention is the component (A), the component (B), and the component (C). The ratios of the components (D) to the total mass of the components (D) are preferably 20 to 60% by mass, 10 to 50% by mass, 10 to 50% by mass, and 20 to 60% by mass, respectively.

(Additive)
The pressure-sensitive adhesive may contain an agent other than the above-mentioned components (A) to (I) as an additive, if necessary. Two or more kinds of additives may be used in combination. Examples of the additive include a surface conditioner, a surfactant, an ultraviolet absorber, a light stabilizer, an inorganic filler, a silane coupling agent, colloidal silica, a defoaming agent, a wetting agent, and a rust preventive.

In one embodiment, the additive content is exemplified by 50, 40, 25, 10, 5, 1, 0.1, less than 0.01 parts by mass, 0 parts by mass, etc. with respect to 100 parts by mass of the pressure-sensitive adhesive. Will be done.

(Adhesive manufacturing method)
The pressure-sensitive adhesive of the present invention comprises (A) component, (B) component, (D) component, (E) component, (F) component and (G) component, and if necessary, (C) component and (H) component. And at least one selected from the group consisting of the above additives. The mixing means and the mixing order are not particularly limited. When the component (B) is used as a diluting solvent when the component (A) is used, the raw material of the pressure-sensitive adhesive of the present invention may be mixed with the solution of the component (B) of the component (A).

(Physical characteristics of adhesive, etc.)
The pressure-sensitive adhesive of the present invention has a Gardner color number (JIS K5600) of preferably 1 or less, preferably a Hazen color number (JIS K5600) of 250 or less, and is excellent in transparency.

Examples of the upper limit of the viscosity (mPa · s / 25 ° C.) of the pressure-sensitive adhesive of the present invention are 10000, 9000, 8000, 7000, 6000, 5000, 4000, 3000, 2000, 1000, 750, 500, 250, 150 and the like. The lower limit is exemplified by 9000, 8000, 7000, 6000, 5000, 4000, 3000, 2000, 1000, 750, 500, 250, 150, 100 and the like. The viscosity range can be set as appropriate (eg, selected from the upper and lower limits). In one embodiment, the viscosity (mPa · s / 25 ° C.) of the pressure-sensitive adhesive of the present invention is preferably 100 to 10000, more preferably 500 to 7000. The above viscosity is a value (5 minutes) measured by an E-type viscometer (TVE-10 (manufactured by Toki Sangyo Co., Ltd.)).

(2. Hardened product)
The present disclosure provides a cured product of the above-mentioned ultraviolet curable pressure-sensitive adhesive. The cured product of the present invention is a cured product of the ultraviolet curable pressure-sensitive adhesive of the present invention, and functions as an adhesive layer.

The method for forming the cured product of the present invention is not particularly limited, and it can be obtained by applying the pressure-sensitive adhesive of the present invention to various plastic film substrates and irradiating them with ultraviolet rays. Examples of the ultraviolet light source include an ultraviolet irradiation device having a xenon lamp, a high-pressure mercury lamp, and a metal halide lamp. Conditions such as the amount of ultraviolet light, the light source, and the transport speed in the device are not particularly limited, and the light amount is preferably about 80 to 160 W / cm and the transport speed is preferably about 3 to 50 m / min.

The plastic film base material is polyethylene terephthalate film (PET film), polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene naphthalate film, polybutylene terephthalate film, Polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. Is illustrated. In addition, these crosslinked films are also used. Further, these laminated films may be used. These films may be those that have been subjected to a light to heavy peeling treatment, or those that are provided with an easy-adhesion layer.

The thickness of the cured product of the present invention is not particularly limited, and may be preferably in the range of about 10 to 1000 μm, more preferably about 25 to 500 μm.

(3. Adhesive sheet)
The present disclosure provides an adhesive sheet using the cured product as an adhesive layer. The pressure-sensitive adhesive sheet of the present invention is an article having the cured product (adhesive layer) of the present invention on at least one side of the plastic film. The sheet can also be processed into a tape and used.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to these examples. In each example, parts and% are all based on mass unless otherwise specified.

In each production example, the weight average molecular weight of the polyurethane (meth) acrylate as the base resin is a polystyrene-equivalent value obtained by gel permeation chromatography, and the measurement conditions are as follows. 8220 GPC ”, Column manufactured by Toso Co., Ltd .: Product name“ TSKGel G1000H ”,“ TSKGel G2000H ”, all developed solvent manufactured by Toso Co., Ltd .: tetrahydrofuran

In each production example, the NCO measurement method for urethane prepolymer is as follows: Measuring device body: Potential difference automatic titrator "Product name AT-400", KEM Co., Ltd. Measuring procedure:
1: Weigh 0.5000 to 1.000 g of the sample in a special weighing bottle.
2: Inject 10 mL of 0.15 mol / L dibutylamine / toluene solution.
3: Place the weighing bottle containing the sample in an ultrasonic cleaner to completely dissolve the sample.
4: Confirm that the sample is completely dissolved, and leave it for 15 minutes (direct sunlight, a place not exposed to heat).
After 5:15 minutes, add 100 mL of isopropyl alcohol to the weighing bottle.
Gently put the stirrer piece in the weighing bottle.
Titrate with a 6: 0.1 mol / L hydrochloric acid solution (f = 1.00) to determine the NCO value.
After inputting the sample amount to be measured into the automatic titrator, the measurement is performed. It is acceptable if the measurement difference is within 0.30. If it is 0.30 or more, measure one again and confirm that it is within 0.30.

Manufacturing example 1
A reactor equipped with a cooling tube, a stirrer and a nitrogen introduction tube, and 869 parts of polypropylene glycol having a weight average molecular weight of 2,000 (manufactured by ADEKA Corporation, trade name "ADEKApolyether P-2000") (hereinafter, PPG2000), After adding 123 parts of dicyclohexylmethanediisocyanate (hereinafter, hydrogenated polymer), 333 parts of 2-ethylhexyl acrylate (hereinafter, 2-EHA) and 0.4 part of dioctyltin dilaurate, the temperature was raised to 80 ° C. and kept warm for 3 hours. A 2-EHA solution of an isocyanate group-terminated urethane prepolymer as an intermediate was obtained. Subsequently, 8 parts of 2-hydroxyethyl acrylate (hereinafter referred to as HEA) was added, and the mixture was kept warm at 80 ° C. for 2 hours, and the completion of the reaction was confirmed by NCO measurement. A 2-EHA solution of a polyurethane acrylate (hereinafter, component (A-1)) having an average number of 2.0 acryloyl groups (meth) was obtained.

Manufacturing example 2
884 parts of PPG2000, 106 parts of isophorone diisocyanate (hereinafter, IPDI), 333 parts of 2-EHA and 0.4 parts of tin octylate were added to the same reaction apparatus as in Production Example 1, and the temperature was raised to 80 ° C. and kept warm for 3 hours. Later, a 2-EHA solution of an isocyanate group-terminated urethane prepolymer as an intermediate was obtained. Subsequently, 10 parts of 4-hydroxybutyl acrylate (hereinafter, 4HBA) was added, and the mixture was kept warm at 80 ° C. for 2 hours, and the completion of the reaction was confirmed by NCO measurement. A 2-EHA solution of a polyurethane acrylate oligomer (hereinafter, component (A-2)) having an average number of meta) acryloyl groups of 2.0 was obtained.

Manufacturing example 3
815 parts of PPG1000, 172 parts of IPDI, 333 parts of 2-EHA and 0.4 parts of tin octylate are added to the same reaction apparatus as in Production Example 1, the temperature is raised to 80 ° C. and the temperature is kept for 3 hours, and then the intermediate is used. A 2-EHA solution of hydroxyl-terminated polyurethane was obtained. Subsequently, 13 parts of 2-isocyanatoethyl methacrylate (manufactured by Showa Denko Co., Ltd., trade name "Karenzu MOI") (hereinafter referred to as MOI) was added, kept warm at 80 ° C. for 2 hours, and the reaction was completed by NCO measurement. By confirmation, a 2-EHA solution of a polyurethane acrylate oligomer (hereinafter, component (A-3)) having a weight average molecular weight of 45,000 and an average number of (meth) acryloyl groups of 2.0 in one molecule was obtained.

Manufacturing example 4
A reaction device equipped with a cooling tube, a stirrer and a nitrogen introduction tube, and 869 parts of polypropylene glycol having a weight average molecular weight of 2,000 (manufactured by ADEKA Corporation, trade name "ADEKApolyether P-2000") (hereinafter, PPG2000), 123 parts of dicyclohexylmethanediisocyanate (hereinafter, hydrogenated MDI), 333 parts of n-butyl acrylate (hereinafter, BA) and 0.4 part of dioctyltin dilaurate were added, and the temperature was raised to 80 ° C. and kept warm for 3 hours, and then the intermediate. A BA solution of an isocyanate group-terminated urethane prepolymer was obtained. Subsequently, 8 parts of 2-hydroxyethyl acrylate (hereinafter referred to as HEA) was added, and the mixture was kept warm at 80 ° C. for 2 hours, and the completion of the reaction was confirmed by NCO measurement. A BA solution of a polyurethane acrylate (hereinafter, component (A-4)) having an average number of 2.0 acryloyl groups (meth) was obtained.

Comparative manufacturing example 1
In the same reactor as in Production Example 1, 910 parts of hydrogenated polybutadiene polyol (manufactured by Nippon Soda Co., Ltd., trade name "NISSO-PB GI-3000"), 81 parts of isophorone diisocyanate and octyl acid having a weight average molecular weight of 4,000. 0.2 part of tin was added, the temperature was raised to 80 ° C. and the temperature was kept warm for 2 hours, and then the reaction completion was confirmed by NCO measurement to obtain a hydroxyl-terminated urethane oligomer as an intermediate. Then, 19 parts of 2-isocyanatoethyl methacrylate was added, and the mixture was kept warm at 80 ° C. for 2 hours. By confirming the completion of the reaction by NCO measurement, the weight average molecular weight was 36,000, and the (meth) acryloyl group in one molecule was confirmed. Polyurethane methacrylate oligomer (a) (hereinafter referred to as component (a)) having an average number of 2.0 was obtained.

Comparative manufacturing example 2
In the same reactor as in Production Example 1, 479 parts of 2-EHA solution of a hydroxyl group-containing acrylic polymer (manufactured by Negami Kogyo Co., Ltd., trade name "Paraclon SY-1062KY"; acrylic polymer 62 wt%, weight average molecular weight 500, 000,2-EHA 38 wt%), 3 parts of MOI, 0.2 parts of tin octylate were added, the temperature was raised to 80 ° C., and the temperature was kept for 4 hours, and then it was confirmed by NCO measurement that the reaction was completed. , A 2-EHA solution of an ethylenically unsaturated bond-containing acrylic polymer (a) (hereinafter, component (a)) having a weight average molecular weight of 500,000 was obtained.

Example 1
The component (A) was the component (A-1) produced in Production Example 1, the component (B) was 2-EHA, the component (C) was isobornyl acrylate (hereinafter IBXA), and the component (D) was HEA, (E). ) Component 1-hydroxycyclohexylphenyl ketone (manufactured by DKSH Japan, trade name "Luna200") (hereinafter, Luna200), (F) component 3,9-bis [2- {3- (3-tert-butyl-) 4-Hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] Undecane (manufactured by Adeca, trade name "Adecastab AO-80" (Hereinafter, AO80), and ditridecyl-3,3'-thiodipropionate (manufactured by Adeca, trade name "Adecastab AO-503") (hereinafter, AO503) as a component (G) are shown in Table 1. A UV curable pressure-sensitive adhesive was obtained by mixing to a percentage of%. Table 2 shows the solvent content, the number of Gardner colors and the viscosity. The content of the component (I) was less than 1% by mass of the pressure-sensitive adhesive.

Examples 2 to 13 and Comparative Examples 1 to 11
The procedure was carried out in the same manner as in Example 1 except that the components were changed as shown in Table 1. The content of the component (I) was less than 1% by mass of the pressure-sensitive adhesive.

表中に記載の使用量（質量％）は、（Ａ）成分、（Ｂ）成分、（Ｃ）成分及び（Ｄ）成分の合計質量に対する比率である。
２−ＥＨＡ：２−エチルヘキシルアクリレート（三菱ケミカル（株）製、商品名「アクリル酸２−エチルヘキシル」）
ＢＡ：ｎ−ブチルアクリレート（三菱ケミカル（株）製、商品名「アクリル酸ブチル」）
ＩＢＸＡ：イソボルニルアクリレート（大阪有機化学（株）製、商品名「ＩＢＸＡ」）
ＨＥＡ：２−ヒドロキシエチルアクリレート（大阪有機化学（株）製、商品名「ＨＥＡ」）
４ＨＢＡ：４−ヒドロキシブチルアクリレート（大阪有機化学（株）製、商品名「４−ＨＢＡ」）
２ＨＢＡ：２−ヒドロキシブチルアクリレート（共栄社化学（株）製、商品名「ライトアクリレートＨＯＢ−Ａ」）
Ｌｕｎａ２００：１−ヒドロキシシクロヘキシルフェニルケトン（ＤＫＳＨジャパン（株）製、商品名「Ｌｕｎａ２００」）
ＴＰＯ：２，４，６−トリメチルベンゾイル−ジフェニルホスフィンオキサイド（ＤＫＳＨジャパン（株）製、商品名「Ｓｐｅｅｄｃｕｒｅ ＴＰＯ」）
Ｉｒｇ．６５１：２，２−ジメトキシ−２−フェニルアセトフェノン（ＢＡＳＦ社製、商品名Ｉｒｇａｃｕｒｅ６５１）
ＡＯ３０：１，１，３−トリス−（２−メチル−４−ヒドロキシ−５−ｔｅｒｔ−ブチルフェニル）ブタン（（株）アデカ製、商品名「アデカスタブＡＯ−３０」）
ＡＯ８０：３，９−ビス［２−｛３−（３−ｔｅｒｔ−ブチル−４−ヒドロキシ−５−メチルフェニル）プロピオニルオキシ｝−１，１−ジメチルエチル］−２，４，８，１０−テトラオキサスピロ［５，５］ウンデカン（（株）アデカ製、商品名「アデカスタブＡＯ−８０」）
ＡＯ５０３：ジトリデシル−３，３’−チオジプロピオネート（（株）アデカ製、商品名「アデカスタブＡＯ−５０３」）
Ｉｒｇａｎｏｘ１７２６：４，６−ビス（ドデシルチオメチル）−Ｏ−クレゾール（ＢＡＳＦ社製、商品名Ｉｒｇａｎｏｘ１７２６）
ＫＥ３１１：水添ロジンエステル（荒川化学工業（株）製、商品名「パインクリスタルＫＥ−３１１」）

The amount used (% by mass) described in the table is a ratio to the total mass of the component (A), the component (B), the component (C) and the component (D).
2-EHA: 2-Ethylhexyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name "2-ethylhexyl acrylate")
BA: n-butyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name "butyl acrylate")
IBXA: Isobornyl acrylate (manufactured by Osaka Organic Chemical Co., Ltd., trade name "IBXA")
HEA: 2-Hydroxyethyl acrylate (manufactured by Osaka Organic Chemical Co., Ltd., trade name "HEA")
4HBA: 4-Hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Co., Ltd., trade name "4-HBA")
2HBA: 2-Hydroxybutyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Light Acrylate HOB-A")
Luna200: 1-Hydroxycyclohexylphenyl ketone (manufactured by DKSH Japan Co., Ltd., trade name "Luna200")
TPO: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (manufactured by DKSH Japan Co., Ltd., trade name "Speedcure TPO")
Irg. 651: 2,2-dimethoxy-2-phenylacetophenone (manufactured by BASF, trade name Irgacure651)
AO30: 1,1,3-Tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane (manufactured by ADEKA CORPORATION, trade name "ADEKA STAB AO-30")
AO80: 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetra Oxaspiro [5,5] Undecane (manufactured by Adeca Co., Ltd., trade name "Adecastab AO-80")
AO503: Ditridecyl-3,3'-thiodipropionate (manufactured by ADEKA CORPORATION, trade name "ADEKA STAB AO-503")
Irganox1726: 4,6-bis (dodecylthiomethyl) -O-cresol (manufactured by BASF, trade name Irganox1726)
KE311: Hydrogenated rosin ester (manufactured by Arakawa Chemical Industry Co., Ltd., trade name "Pine Crystal KE-311")

For each of the pressure-sensitive adhesives of Examples and Comparative Examples, compatibility, Gardner color number, solvent content and viscosity were evaluated and measured under the following criteria and conditions.
<Compatibility>
◯: Uniform and completely transparent ×: Confirm any of cloudiness, sediment, insoluble matter and liquid phase separation

<Number of Gardner colors>
Measured value according to JIS K5600.

<Solvent content>
Measured value of gas chromatograph device under the following conditions.
(Analysis equipment)
GC: Agilent 6850 (manufactured by Agilent Technologies, Inc.)
(GC measurement conditions)
GC column: HP-1 (manufactured by Agilent Technologies, Inc.)
Column temperature: 50 ° C (10 min) → 10 ° C / min → 300 ° C (10 min)
Column flow rate: 2.0 ml / min
Carrier gas: Helium injection method: Split (50: 1)
Detection temperature: 300 ° C

<Viscosity (mPa · s)>
E-type viscometer (TVE-10 (manufactured by Toki Sangyo Co., Ltd.) measured at 25 ° C and 5 minutes.

The following measurements, tests and evaluations were carried out for each of the UV curable pressure-sensitive adhesives of Examples and Comparative Examples.

1. 1. Adhesive strength test (1) Apply the adhesive on a 75 μm thick heavy peeling polyester film (manufactured by Panac Co., Ltd., trade name “SP-PET-03-75BU”) so that the film thickness after curing is 250 μm. After coating, the peeling-treated surface of a 38 μm-thick light peel-treated polyester film (manufactured by Panac Co., Ltd., trade name “SP-PET-01-38BU”) is attached to the pressure-sensitive adhesive composition coating layer. Next, the obtained coating film was irradiated with ultraviolet rays in the air with a high-pressure mercury lamp (100 mW / cm ² , 900 mJ / cm ² ) to form a laminated film containing an adhesive layer (light peeling polyester film / adhesive layer /). A polyester film with heavy peeling treatment) was produced.
(2) Next, the heavy peeling polyester film of the laminated film is peeled off, a 50 μm polyester film (Cosmo Shine A-4300 manufactured by Toyobo Co., Ltd.) is bonded with a 2 kg roller, and then the light peeling polyester film is applied. Peel off and attach the single-sided adhesive sheet to the glass plate with a 2 kg roller to prepare a laminate for adhesion test (Cosmo Shine A-4300 / adhesive layer / glass plate), which is 24 at 25 ° C. and 50% RH. I left it for a while.
(3) Next, the adhesive strength (N / 25 mm) was measured by peeling the single-sided adhesive sheet from the glass plate in the 180 ° direction at a speed of 300 mm / min. For the measurement, a commercially available machine (manufactured by AND Co., Ltd., Tensilon universal material tester) was used.

2. Removability test of the adhesive layer The adhesive residue state on the glass plate after the adhesive strength test of item 1. (3) was visually evaluated according to the following criteria.
◯: No adhesive residue △: Some adhesive residue is present ×: There is adhesive residue on the entire surface of the glass

3. 3. Transparency evaluation Item 1. The haze value of the adhesive test laminate according to (2) and the haze value after allowing it to stand in a constant temperature and humidity chamber at a temperature of 85 ° C. and 85% RH for 500 hours are the colors manufactured by Murakami Color Technology Laboratory. The measurement was performed according to JIS K 5400 using a haze meter. The obtained haze value is a value including the haze value of the base material (Cosmo Shine A-4300 and the glass plate).

4. Evaluation of durability of adhesive layer Item 1. The adhesive test laminate according to (2) was allowed to stand in a constant temperature and humidity chamber at a temperature of 85 ° C. and 85% RH for 500 hours, and then the durability of the adhesive layer was evaluated according to the following criteria.
◯: No peeling of the base material, air bubbles in the adhesive layer, or damage to the adhesive layer ×: At least one defect of peeling of the base material, air bubbles in the adhesive layer, or damage to the adhesive layer occurs.

5. Heat-resistant yellowing evaluation The above item 1. The adhesive test laminate according to (2) was measured for yellowing (b *) before the heat resistance test with a spectral color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "spectral color difference meter SE6000"). Further, after allowing to stand in a constant temperature bath at a temperature of 105 ° C. for 250 hours, the degree of yellowing (b *) was measured in the same manner. The change in the degree of yellowing of the adhesive layer (Δb *) was evaluated. The smaller the change in the degree of yellowing of the adhesive layer (Δb *), the better the heat-resistant yellowing.

6. Holding power test Item 1. The single-sided adhesive sheet according to (2) was attached to a stainless steel plate with a 2 kg roller and left to stand for 24 hours under the conditions of 25 ° C. and 50% RH. Next, according to JISZ-1524, a load of 1 kg is vertically applied to one end of the single-sided adhesive sheet in a holding force tester with a constant temperature bath (manufactured by Tester Sangyo Co., Ltd., creep tester (with a constant temperature bath)). The time until the adhesive tape slipped off was measured under the condition of 105 ° C.

Claims (8)

It is a reaction product of (A) (a1) polyether polyol, (a2) aliphatic polyisocyanate, and (a3-1) hydroxyl group-containing mono (meth) acrylate or (a3-2) isocyanate group-containing mono (meth) acrylate. Polyurethane (meth) acrylate,
(B) Alkyl mono (meth) acrylate having 4 to 12 carbon atoms in the alkyl group,
(C) Cycloalkyl mono (meth) acrylate having 6 to 10 carbon atoms in the cycloalkyl group,
(D) Mono (meth) acrylate containing a primary hydroxyl group,
(E) One or more photopolymerization initiators selected from the group consisting of α-hydroxyalkylphenone-based photopolymerization initiators and acylphosphine oxide-based photopolymerization initiators.
(F) Hindered phenolic antioxidants, as well as
(G) Contains a thioether-based antioxidant,
The component (E) is 0.1 to 2% by mass and the component (F) is 0.1 to 2 with respect to the total mass of the component (A), the component (B), the component (C), and the component (D). The mass%, the component (G) is 0.1 to 2% by mass, and the tackifier resin (H) is 5% by mass or less.
The mass ratio ((F) / (G)) of the component (F) to the component (G) is 0.7 to 2.0.
(I) The content of the ultraviolet non-reactive solvent is less than 1% by mass.
UV curable adhesive. The ratios of the components (A), (B), (C) and (D) to the total mass are 20 to 60% by mass, 10 to 50% by mass, 10 to 50% by mass, and so on, respectively. The ultraviolet curable pressure-sensitive adhesive according to claim 1, which is 20 to 60% by mass. The ultraviolet curable pressure-sensitive adhesive according to claim 1 or 2, wherein the component (A) has a weight average molecular weight of 10,000 to 90,000. The ultraviolet curable pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the component (E) is 1-hydroxycyclohexylphenyl ketone and / or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. The ultraviolet curable pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the component (F) is a semi-hindered phenolic antioxidant. The claim that the component (H) is at least one selected from the group consisting of a rosin derivative, a hydrogenated resin of a rosin and a rosin derivative, a hydrogenated resin of a terpenphenol resin, and a hydrogenated resin of a petroleum resin. The ultraviolet curable pressure-sensitive adhesive according to any one of 1 to 5. The cured product of the ultraviolet curable pressure-sensitive adhesive according to any one of claims 1 to 6. An adhesive sheet using the cured product of claim 7 as an adhesive layer.