JP5221846B2 - UV curable adhesive for optical sheet formation and optical sheet - Google Patents

Description

The present invention relates to an optical sheet and an ultraviolet curable adhesive for forming an optical sheet. More specifically, a prism sheet, a collimator lens, a Fresnel lens, a lenticular lens, a light reflecting lens, a hologram, an AR sheet, an AG sheet, an LR sheet, etc. It relates to adhesives.

Recently, as the needs for thinning liquid crystal displays and projection TVs and increasing the demand for miniaturization of images, the resin for optical sheets such as prism sheets, Fresnel lenses and lenticular lenses, which have the fine optical structures used for them, are used. A resin having a high refractive index has been developed (see, for example, Patent Document 1) and is becoming thinner. However, the sheet strength is weakened by being thinned, and it is difficult to increase the size. In order to solve this problem, a method of reinforcing the optical sheet with a transparent sheet imparting rigidity has been proposed. As an adhesive for adhering these sheets in the method, a resin composition comprising a thermoplastic resin and a polyisocyanate, a thermoplastic resin and an acrylate compound, and a polyisocyanate and a polyester is disclosed (for example, Patent Documents). 2), here, in order to increase the curing rate, a method using an ultraviolet curable resin is being studied.
JP-A-5-65318 JP-A-10-158349

However, these ultraviolet curable adhesives have problems such as poor adhesion (strain due to moisture absorption or temperature change, etc.) and poor light resistance (yellowing due to ultraviolet rays, peeling, etc.).
The objective of this invention is providing the ultraviolet curable adhesive for optical sheet formation which is excellent in adhesiveness, transparency, and light resistance, and an optical sheet using this adhesive.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems. That is, the present invention comprises an ultraviolet curable adhesive for forming an optical sheet (A) a polyether polyol (a1), an alicyclic polyisocyanate (a2), and a hydroxyl group-containing (meta), comprising the following (A) to (D). Urethane (meth) acrylate (B) monofunctional (meth) acrylate (C) having an alicyclic structure formed from acrylate (a3) Monofunctional (meth) acrylate R—Ph—O represented by the following general formula (1) (CH ₂ CH ₂ O) _n COCR ′ = CH ₂ (1)
(In the formula, R represents H or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, R ′ represents H or a methyl group, Ph represents a phenylene group, and n represents an integer of 1 to 4)
(D) selected from the group consisting of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and methylphenylglyoxyester 1 type, or 2 or more types of photopolymerization initiators; resin layer (I) having fine protrusions on the surface, adhesive intermediate layer (II) obtained by curing the adhesive, and transparent group imparting rigidity and smoothness An optical sheet comprising three layers of the material layer (III); and a resin layer having fine protrusions on the surface by applying the adhesive on the transparent base layer (III) imparting rigidity and smoothness. (I), (II), characterized in that the back surface of I) is laminated thereon, and thereafter the adhesive is cured by ultraviolet irradiation to form an adhesive intermediate layer (II). A and (III) The method for manufacturing an optical sheet composed of three layers.

The ultraviolet curable adhesive for forming an optical sheet of the present invention, the optical sheet using the adhesive, and the production method thereof have the following effects.
(1) The adhesive of this invention is excellent in adhesiveness, transparency, and light resistance.
(2) The optical sheet using the adhesive is excellent in strength, can be made thin and large, and is excellent in transparency and light resistance.
(3) The method for producing an optical sheet of the present invention is excellent in productivity.

The ultraviolet curable adhesive for forming an optical sheet of the present invention comprises the following (A) to (D).
(A) A monofunctional (meth) having a urethane (meth) acrylate (B) alicyclic structure formed from a polyether polyol (a1), an alicyclic polyisocyanate (a2), and a hydroxyl group-containing (meth) acrylate (a3) Acrylate (C) Monofunctional (meth) acrylate R—Ph—O (CH ₂ CH ₂ O) _n COCR′═CH ₂ (1) represented by the following general formula (1)
(In the formula, R represents H or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, R ′ represents H or a methyl group, Ph represents a phenylene group, and n represents an integer of 1 to 4)
(D) selected from the group consisting of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and methylphenylglyoxyester One or more photoinitiators

(A) in the present invention is a urethane (meth) acrylate formed from a polyether polyol (a1), an alicyclic polyisocyanate (a2), and a hydroxyl group-containing (meth) acrylate (a3).
Moreover, the urethane (meth) acrylate of (A) may be used by 1 type, and may use 2 or more types together.

(A1) is a number average molecular weight [hereinafter abbreviated as Mn, and measurement is by gel permeation chromatography (GPC) method. same as below. 200 to 5,000 polyether polyols, and the polyether polyols include bifunctional ones [polyethylene glycol (hereinafter abbreviated as PEG), polypropylene glycol (hereinafter abbreviated as PPG), polytetramethylene glycol ( Hereinafter abbreviated as PTMG), etc.], trifunctional or higher (AO adducts of trihydric or higher polyhydric alcohols described later, etc.), and mixtures thereof.
Among these, polyethylene glycol is preferable from the viewpoint of light resistance, and polytetramethylene glycol is more preferable.

(A1) as a polyol component may be used in combination with other low molecular weight polyvalent (divalent to octavalent or higher) alcohol (a4) (molecular weight of 62 or more and less than Mn200) as necessary. As (a4), divalent [ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-pentanediol, neopentyl glycol, 1,6-hexanediol ( Hereinafter, EG, DEG, TEG, PG, DPG, BD, PD, NPG, HD, etc.)], trivalent [glycerin, trimethylolpropane (hereinafter, abbreviated as GR, TMP, respectively), etc.], tetravalent [ Pentaerythritol, diglycerin (hereinafter abbreviated as PE, DGR, etc.), hexavalent [dipentaerythritol (hereinafter abbreviated as DPE), etc.], and octavalent [sucrose, etc.] alcohol.

The amount of (a4) used based on the weight of (a1) is preferably 20% or less, more preferably 5 to 10%, from the viewpoints of adhesiveness and resin strength.

(A2) includes an alicyclic polyisocyanate having 4 to 50 carbon atoms (hereinafter abbreviated as C) (hereinafter abbreviated as PI), such as diisocyanate (hereinafter abbreviated as DI), trifunctional or higher PI and These mixtures are included.
The alicyclic DI includes isophorone DI (IPDI), 2,4- and / or 2,6-methylcyclohexane-DI (hydrogenated TDI), dicyclohexylmethane-4,4′-DI (hydrogenated MDI), cyclohexyl. Silene DI, methylcyclohexylene DI, bis (2-isocyanatoethyl) -4-cyclohexylene-1,2-dicarboxylate and 2,5- and / or 2,6-norbornane DI, dimer acid DI (DDI) Etc .; Examples of the trifunctional or higher PI include bicycloheptane triisocyanate, biuret and isocyanurate of the isocyanate. Of these, IPDI, hydrogenated TDI and hydrogenated MDI are preferred from the viewpoint of adhesiveness.

(A3) of the present invention includes the following and mixtures thereof.
(A31) Alkylene oxide (C2-4, hereinafter abbreviated as AO) adduct (molecular weight 116 to Mn5,000) of (meth) acrylic acid
(Meth) acrylic acid-2-hydroxy-ethyl, -propyl and -butyl, and their AO adducts, etc. (a32) and ε-caprolactone adducts of (a31) (molecular weight 230 to Mn5,000)
(Meth) acrylic acid-2-hydroxyethyl-ε-caprolactone 2-mole adduct, etc. (a33) Reaction product of epoxide and (meth) acrylic acid (molecular weight 222 to Mn 4,000)
3-phenoxy-2-hydroxypropyl (meth) acrylate, 3-biphenoxy-2-hydroxypropyl (meth) acrylate, etc. (a34) (meth) acrylate of trifunctional or higher polyol (molecular weight 92 to Mn5,000) Glycerin mono- and di (meth) acrylate, trimethylolpropane mono- and di (meth) acrylate, pentaerythritol mono-, di- and tri (meth) acrylate, ditrimethylolpropane mono-, di- and tri (meth) acrylate Of these, dipentaerythritol mono-, di-, tri-, tetra- and penta (meth) acrylates, and their AO adducts (addition mole number 1 to 100) are preferred from the viewpoint of adhesiveness (a31 ), More preferred from the viewpoint of light resistance Ino is (meth) -2-hydroxyethyl acrylate.

The total ratio of (a1) in (A) and (a4) used together as necessary is preferably 40 to 85% by weight, more preferably 50 to 75% by weight, from the viewpoint of elongation of the cured product. The proportion of (a3) in (A) is preferably 5 to 20% by weight, more preferably 6 to 15% by weight, from the viewpoint of curing speed. In addition, the weight ratio [[(a1) + (a4)] / (a3)] of the total amount of (a1) and (a4) used together if necessary and (a3) is preferably from the viewpoint of toughness of the cured product. 3/1 to 22/1, more preferably 4/1 to 15/1.

The production method of (A) is not particularly limited, but (1) (a1), (a2), (a3) and, if necessary, (a4) are collectively charged and urethanized at 40 to 100 ° C., (2) A method in which (a1), (a2) and, if necessary, (a4) are subjected to a urethanization reaction at 40 to 150 ° C. to be prepolymerized, then charged with (a3) and reacted at 40 to 100 ° C., and ( 3) A method in which (a2) and (a3) are urethanated at 40 to 100 ° C in advance and prepolymerized, and then (a1) and, if necessary, (a4) are charged and reacted at 40 to 100 ° C. .
In the production of (A), the NCO / OH equivalent ratio of the isocyanate group of (a2) and the total hydroxyl group of (a1), (a3) and (a4) is usually 0.6 / 1 to 1.2 /. 1. From the viewpoint of toughness, the preferable lower limit is 0.8 / 1, and from the viewpoint of storage stability of (A), the preferable upper limit is 1.1 / 1. Further, the NCO / OH equivalent ratio of the isocyanate group of (a2) and the total hydroxyl group of (a1) and (a4) is usually 1.1 / 1 to 2.0 / 1, and the upper limit preferable from the viewpoint of elongation is From the viewpoint of 1.75 / 1, reactivity and transparency, the preferred lower limit is 1.25 / 1.

In the production of (A), it is preferable to use the urethanization catalyst (a5). Examples of (a5) include various compounds used in urethanization reactions, such as amine catalysts [tertiary amines such as triethylenediamine and 1,8-diazabicyclo (5,4,0) undecene-7 [DBU: San Apro Co., Ltd.] And a metal (tin, lead, bismuth, etc.) catalyst (stannas octoate, dibutyltin dilaurate, lead octenoate, etc.). Among these, a metal catalyst is preferable from the viewpoint of transparency, reactivity, and stability, and an organic bismuth compound is more preferable. The following are mentioned as an organic bismuth compound.

(A51) Organic bismuth carboxylate represented by the general formula Bi (COOR ¹ ) ₃ and R ¹ is a monovalent aliphatic group [C1-20, such as alkyl (methyl, ethyl, n- and i-propyl, n -, I-, sec- and t-butyl, octyl, 2-ethylhexyl, decyl and dodecyl) and alkenyl (1-, 2- and i-propenyl, 1-, 2- and 3-butenyl) groups], aromatic (Aliphatic) group (C6-20, such as phenyl, toluyl, xylenyl, benzyl, phenethyl and hexylphenyl) groups and alicyclic (C3-10, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cyclooctyl) groups, etc. .
Among these R ^1, a C2-12 aliphatic group and a C5-10 alicyclic group are preferable from the viewpoint of hydrolysis resistance.

(A52) represented by an organic bismuth alkoxide formula _{^{Bi (OR 1) 3, R}} 1 is as defined above, preferably ^{R 1} from the viewpoint of hydrolysis resistance is the same as above.

(A53) Compound having dicarbonyl group and Bi chelate compound The compound having a dicarbonyl group includes C4-15 compounds such as acetylacetone, acetylacetic acid, acetoacetoxyethyl (meth) acrylate, These and Bi chelate compounds are included.

Of these (a5), (a51) is preferred from the viewpoints of reaction rate and stability.

The amount of (a5) used is preferably 0.001 to 0.5%, more preferably 0.005 to 0.2% from the viewpoint of reactivity and transparency, based on the weight of (A).

In the production of (A), the reaction may be carried out by diluting with a solvent (ethyl acetate, methyl ethyl ketone, toluene, etc.) if necessary. The amount of the solvent used is usually 5,000% or less based on the weight of (A), the upper limit is preferably 1,000% from the viewpoint of reaction rate, and the lower limit is preferably 10% from the viewpoint of handleability of (A). is there.

The urethanization reaction can be carried out at normal pressure, reduced pressure or increased pressure. The progress of the urethanization reaction can be judged, for example, by measuring the NCO% and hydroxyl value of the reaction system.

Mn of (A) is preferably 500 to 8,000 from the viewpoint of the toughness of the cured product, the viscosity of the adhesive, and the transparency of the cured product, more preferably 1,000, and even more preferably 5,000. is there.

As monofunctional (meth) acrylate (B) having an alicyclic structure in the present invention, C8-20, for example, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, dicyclopentadiene (meta) ) Acrylate, norbornene (meth) acrylate, morpholine (meth) acrylate, morpholine ethylene glycol (meth) acrylate, adamantane (meth) acrylate, and mixtures thereof. Of these, isobornyl (meth) acrylate, dicyclopentadiene (meth) acrylate, norbornene (meth) acrylate, and mixtures thereof are preferable from the viewpoint of elongation of the adhesive.
Moreover, the monofunctional (meth) acrylate which has (B) alicyclic structure may be used by 1 type, and may use 2 or more types together.

(C) in the present invention is a monofunctional (meth) acrylate represented by the following general formula (1).
R—Ph—O (CH ₂ CH ₂ O) _n COCR′═CH ₂ (1)
In the formula, R is H or C 1-12 (preferably H or C 1-9) monovalent aliphatic hydrocarbon group (methyl, ethyl, butyl, hexyl, 2-ethylhexyl, dodecyl group, etc.), R ′ is H Or a methyl group, Ph is a phenylene group, n represents the integer of 1-4 (preferably 1-2).
When R is a hydrocarbon group, if C exceeds 12, the toughness of the resin deteriorates. Moreover, when n exceeds 4, adhesiveness will worsen.
Moreover, the monofunctional (meth) acrylate shown by General formula (1) of (C) may be used by 1 type, and may use 2 or more types together.

The photopolymerization initiator (D) in the present invention includes 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and methylphenyl. One or more photopolymerization initiators selected from the group consisting of glyoxyesters.

In the adhesive of the present invention, (A) is a component that imparts toughness and elongation to the cured product, (B) is an adhesive property and elongation to the cured product, and (C) is a component that imparts adhesiveness to the cured product.

The weight ratio of (A), (B), (C) and (D) in the adhesive of the present invention is preferably based on the total weight of (A) to (D) from the viewpoint of the characteristics of the above components. (A) is 20 to 69%, (B) is 10 to 50%, (C) is 20 to 60%, and (D) is 0.3 to 0.9% (more preferably 0.4 to 0). 0.8%, particularly preferably 0.5 to 0.7%).

Further, the weight ratio of (B) / (C) in the adhesive of the present invention is preferably 0.3 from the viewpoint of the balance of adhesiveness with the resin layer (I) and the transparent substrate layer (III) described later. / 1 to 1.5 / 1, more preferably 0.5 / 1 to 1.2 / 1.

The adhesive of the present invention may further contain (meth) acrylate (E) other than (A), (B) and (C) as long as it does not inhibit the effects of the present invention. (E) includes the following, which may be used alone or in combination of two or more.

(E1) Mono (meth) acrylate (E11) Aliphatic monohydric alcohol (C1-30) (meth) acrylate Lauryl (meth) acrylate, stearyl (meth) acrylate, etc. (E12) Aliphatic monohydric alcohol (C1-30 ) AO 1-30 mol adduct (meth) acrylate lauryl alcohol ethylene oxide (hereinafter abbreviated as EO) 2 mol adduct (meth) acrylate, lauryl alcohol propylene oxide (hereinafter abbreviated as PO) 3 mol adduct (Meth) acrylate, etc. (E13) [alkyl (C1-20)] phenol (C6-30) EO 5-30 mol adduct (meth) acrylate phenol EO 10 mol adduct (meth) acrylate, nonylphenol EO6 Mole adduct (meth) acrylate, etc. (E14) Ruarukiru (C7～26) phenol (C6-30) of EO1~10 molar adduct of (meth) acrylate paracumylphenol of EO1 mole adduct (meth) acrylate

(E2) Di (meth) acrylate (E21) (poly) oxyalkylene (C2-4) (molecular weight 62-Mn3,000) of di (meth) acrylate PEG (Mn400), PPG (Mn200) and PTMG (Mn650) Each di (meth) acrylate such as (E22) di (meth) acrylate bisphenol A, -F and -S of EO2 mol and PO4 mol adduct of bisphenol compound (C12-C15) (C12-C15) (E23) Di (meth) acrylate NPG of aliphatic dihydric alcohol (C2-30), etc. (E24) Divalent alcohol having alicyclic structure (C6-30) Di (meth) acrylate dimethylol tricyclodecane di (meth) acrylate, cyclo Cyclohexanedicarboxylic dimethanol di (meth) acrylates and di (meth) acrylate of hydrogenated bisphenol A

(E3) poly (n = 3-6 or more) (meth) acrylate (E31) poly (meth) acrylate TMP tri (meth) of polyvalent (trivalent to hexavalent or more) alcohol (C3-40) Acrylate, GR tri (meth) acrylate, tri (meth) acrylate of TMP PO3 mol adduct, tri (meth) acrylate of TMP EO3 mol adduct, tri (meth) acrylate of PE, tetra (meth) acrylate of PE , Tetra (meth) acrylate of PE EO4 mole adduct, hexa (meth) acrylate of DPE, etc.

(E4) Polyester (meth) acrylate obtained by esterification of polyvalent (divalent to tetravalent or higher) carboxylic acid, polyvalent (divalent to octavalent or higher) alcohol and (meth) acryloyl group-containing compound Polyester (meth) acrylate having a plurality of ester bonds and a plurality of (meth) acryloyl groups and having a molecular weight of 150 to Mn 4,000 As the polyvalent carboxylic acid, for example, an aliphatic polyvalent carboxylic acid [C3-20, such as malonic acid, Maleic acid (anhydride), adipic acid, sebacic acid, succinic acid, reaction product of acid anhydride (reaction product of diPE and maleic anhydride, etc.), and aromatic polycarboxylic acid [C8-30, for example, isophthalic acid Terephthalic acid, phthalic acid (anhydride) and trimellitic acid (anhydride)].

As this polyhydric alcohol, the low molecular weight polyhydric alcohol illustrated as said (a4) is mentioned.
Examples of the (meth) acryloyl group-containing compound include C3-30, such as (meth) acrylic acid and hydroxymethyl (meth) acrylate.

(E5) A butadiene polymer having a (meth) acryloyl group in the main chain and / or side chain [Mn 500 to 500,000, for example, polybutadiene di (meth) acrylate]
(E6) Siloxane polymer having a (meth) acryloyl group in the main chain and / or side chain of dimethylpolysiloxane [Mn 300 to 20,000, for example, dimethylpolysiloxane di (meth) acrylate]
Among these, (E2), (E3) and (E4) are preferable from the viewpoint of toughness of the cured product.

The amount of (E) used is usually 50% or less based on the total weight of (A) to (C), preferably 2 to 20% from the viewpoint of toughness, adhesiveness and light resistance of the cured product, Preferably it is 3 to 15%.

In the adhesive of the present invention, various additives (F) used for the adhesive may be further contained as necessary within a range not inhibiting the effects of the present invention. (F) includes inorganic fine particles (F1), dispersant (F2), antifoaming agent (F3), leveling agent (F4), silane coupling agent (F5), thixotropic agent (thickening agent) (F6). ), Slip agent (F7), antioxidant (F8) and / or ultraviolet absorber (F9).
The total amount of (F) used is usually 30% or less, preferably 0.005 to 20%, based on the total weight of the adhesive of the present invention (solid content, hereinafter the same).

(F1) includes alumina [aluminum oxide, alumina white (alumina hydrate), silica-alumina (a fused product of alumina and silica, alumina coated with silica, etc.)], zirconia, tungsten carbide, titanium carbide , Silicon carbide, boron carbide, diamond, carbon black (channel black, furnace black, thermal black, acetylene black, etc.), silica (fine powder silicic acid, hydrous silicic acid, diatom, colloidal silica, etc.), silicate (fine powder silica) Magnesium oxide, talc, soapstone, stearite, calcium silicate, magnesium aluminosilicate, sodium aluminosilicate, etc.), carbonate [precipitate (active, dry, heavy or light) calcium carbonate, magnesium carbonate, etc.], clay ( Kaolin crepe , Sericite clay, vilophyllite clay, montmorillonite clay, bentonite, acid clay, sulfate (aluminum sulfate (sulfate band, satin white, etc.), barium sulfate (barite powder, precipitated barium sulfate, lithopone, etc.) ), Magnesium sulfate, calcium sulfate (stone kou) (anhydrous koji, hemihydrate koji, etc.)], lead white, mica powder, zinc white, titanium oxide, activated calcium fluoride, cement, lime, calcium sulfite, disulfide Examples include molybdenum, asbestos, glass fiber, lock fiber, and microballoon.

Of these, alumina, silica, silicate, carbonate, sulfate and titanium oxide are preferable from the viewpoint of scratch resistance of the cured product and suppression of coloring of the adhesive and the cured product, and silica, calcium carbonate, Barium sulfate and titanium oxide.
(F1) may be used in combination of two or more, or two or more may be combined (for example, titanium oxide is fused to silica). The shape of (F1) is not particularly limited, and may be any of an indefinite shape, a spherical shape, a hollow shape, a porous shape, a petal shape, an aggregated shape, and a granular shape, for example. The amount of (F1) used is usually 20% or less based on the total weight of the adhesive of the present invention, preferably 15% or less, more preferably 3 to 10%, from the viewpoint of the flexibility of the cured product.

Examples of (F2) include organic dispersants [polymer dispersants (Mn 2,000 to 500,000) and low molecular dispersants (molecular weight 100 to less than Mn 2,000)] and inorganic dispersants.

As the polymer dispersing agent, naphthalene sulfonate [alkali metal (Na and K etc.) salt, ammonium salt etc.] formalin condensate, polystyrene sulfonate (same as above), polyacrylate (same as above) , Poly (2-4) carboxylic acid (maleic acid / glycerin / monoallyl ether copolymer etc.) salt (same as above), carboxymethyl cellulose (Mn 1,000-10,000) and polyvinyl alcohol (Mn 1,000-100) , 000) and the like.

Examples of the low molecular dispersant include the following.
(1) AO (C2-4) of polyoxyalkylene type aliphatic alcohol (C4-30), [alkyl (C1-30)] phenol, aliphatic (C4-30) amine and aliphatic (C4-30) amide 1-30 mol adduct fatty alcohols include n-, i-, sec- and t-butanol, octanol, dodecanol and the like; (alkyl) phenols include phenol, methylphenol and nonylphenol; aliphatic amines , Laurylamine, methylstearylamine and the like; and aliphatic amides include stearic acid amide and the like.
(2) Monoester compound of polyhydric alcohol type C4-30 fatty acid (lauric acid, stearic acid, etc.) and polyhydric (2-6 or more) alcohol (eg GR, PE, sorbitol and sorbitan) (3) Carvone Alkali metal (same as above) salt of acid salt type C4-30 fatty acid (same as above) (4) Sulfuric acid ester type C4-30 fatty alcohol (same as above) and aliphatic alcohol AO (C2-4) 1) 30 mol adduct sulfate alkali metal (same as above) salts, etc.

(5) Sulfonate type [alkyl (C1-30)] Phenol (same as above) sulfonate alkali metal (same as above) salt (6) Phosphate ester type C4-30 aliphatic alcohol (same as above) ) And fatty alcohol AO (C2-4) 1-30 mol adduct mono- or diphosphate salts [alkali metal (same as above) salts, quaternary ammonium salts, etc.]
(7) Primary to tertiary amine salt type C4-30 aliphatic amine [primary (laurylamine etc.), secondary (dibutylamine etc.) and tertiary amine (dimethylstearylamine etc.) hydrochloride, triethanolamine And inorganic acids (hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc.) of monoesters of C4-30 fatty acids (same as above) (8) Quaternary ammonium salt type C4-30 quaternary ammonium (butyltrimethylammonium, diethyl) Laurylmethylammonium, dimethyldistearylammonium, etc.) inorganic acids (same as above)

Examples of inorganic dispersants include alkali metal salts of polyphosphoric acid (same as above) and phosphoric acid dispersants (such as phosphoric acid, monoalkyl phosphate ester, dialkyl phosphate ester).
The amount of (F2) used is usually 10% or less, preferably 0.05 to 5%, based on the total weight of the adhesive of the present invention.

As (F3), lower alcohol (C1-6) (methanol, butanol, etc.), higher alcohol (C8-18) (octyl alcohol, hexadecyl alcohol, etc.), higher fatty acid (C10-20) (oleic acid, stearic acid) Etc.), higher fatty acid esters (C11-30) (glycerin monolaurate, etc.), phosphate esters (tributyl phosphate, etc.), metal soaps (calcium stearate, aluminum stearate, etc.), polyethers [PEG (Mn 200-10,000) ), PPG (Mn 200 to 10,000), etc.], silicone (dimethyl silicone oil, alkyl-modified silicone oil, fluorosilicone oil, etc.) and mineral oil (silica powder dispersed in mineral oil).
The amount of (F3) used is usually 3% or less, preferably 0.01-2%, based on the total weight of the adhesive of the present invention.

(F4) includes PEG type nonionic surfactants (nonylphenol EO 1-40 mol adduct, stearic acid EO 1-40 mol adduct, etc.), polyhydric alcohol type nonionic surfactants (sorbitan palmitic acid monoester, sorbitan) Stearic acid monoesters, sorbitan stearic acid triesters, etc.), fluorosurfactants (perfluoroalkyl EO 1-50 mol adducts, perfluoroalkyl carboxylates, perfluoroalkyl betaines, etc.), modified silicone oils [(E6) , (F3) and (F7), for example, polyether-modified silicone oil] and the like.
The amount of (F4) used is usually 3% or less, preferably 0.1 to 2%, based on the total weight of the adhesive of the present invention.

(F5) includes those other than (E6), (F3) and (F7), such as amino group-containing silane coupling agents (γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-phenylamino). Propyltrimethoxysilane, etc.), ureido group-containing silane coupling agents (ureidopropyltriethoxysilane, etc.), vinyl group-containing silane coupling agents [vinylethoxysilane, vinylmethoxysilane, vinyltris (β-methoxyethoxy) silane, etc.], Methacrylate group-containing silane coupling agents (γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, etc.), epoxy group-containing silane coupling agents (γ-glycidoxypropyltrimethoxysilane, etc.), isocyanate -Containing silane coupling agent (γ-isocyanatopropyltriethoxysilane etc.), polymer type silane coupling agent (polyethoxydimethylsiloxane etc.), cationic type silane coupling agent [N- (N-benzyl-β-aminoethyl)- γ-aminopropyltrimethoxysilane hydrochloride, etc.].
The amount of (F5) used is usually 10% or less, preferably 0.5 to 7%, based on the total weight of the adhesive of the present invention.

Examples of (F6) include inorganic thixotropy imparting agents (such as bentonite, organically treated bentonite, and ultrafine surface-treated calcium carbonate) and organic thixotropic properties imparting agents (hydrogenated castor oil wax, calcium stearate, aluminum oleate, polymerized linseed oil, etc. ).
The amount of (F6) used is usually 20% or less, preferably 0.5 to 10%, based on the total weight of the adhesive of the present invention.

(F7) includes higher fatty acid esters (such as butyl stearate), higher fatty acid amides (such as ethylene bis stearic acid amide and oleic acid amide), metal soaps (such as calcium stearate and aluminum oleate), waxes [paraffin wax, polyolefins And wax (polyethylene wax, polypropylene wax, carboxyl group-containing polyethylene wax, etc.) and silicone (for example, dimethyl silicone oil, alkyl-modified silicone oil and fluorosilicone oil).
The amount of (F7) used is usually 5% or less, preferably 0.01-2%, based on the total weight of the adhesive of the present invention.

(F8) includes hindered phenol compounds [triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3,5-di-t-butyl -4-hydroxybenzylphosphonate diethyl ester etc.] and amine compounds (n-butylamine, triethylamine, diethylaminomethyl methacrylate etc.) and the like.
The amount of (F8) used is usually 3% or less, preferably 0.005 to 2%, based on the total weight of the adhesive of the present invention.

(F9) includes benzotriazole compounds [2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2- (3 , 5-di-t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, etc.], triazine compounds [2- ( 4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol], benzophenone (such as 2-hydroxy-4-n-octyloxybenzophenone), oxalic anilide Compound (2-ethoxy-2'-ethyloxalic acid bisanilide etc.) etc. are mentioned.
The amount of (F9) used is usually 3% or less, preferably 0.005 to 2%, based on the total weight of the adhesive of the present invention.

When the additives are the same and overlap between (F1) to (F9) above, the amount of each additive exerting the corresponding additive effect is not used regardless of the effect as the other additive, Considering that the effects as other additives can be obtained at the same time, the amount used is adjusted according to the purpose of use.

If necessary, the adhesive of the present invention can further contain a thermosetting catalyst as long as the effects of the present invention are not impaired. What added the thermosetting catalyst can be hardened | cured with heat other than an ultraviolet-ray, and can obtain the hardened | cured material excellent in adhesiveness and light resistance. In the case of curing by heat, it is usually heat-treated in an oven at 50 to 200 ° C, preferably 80 to 180 ° C for 1 minute to 20 hours.

Examples of the thermosetting catalyst include peroxides (t-butyl peroxybenzoate, benzoyl peroxide, methyl ethyl ketone peroxide, etc.) and azo compounds (azobisisobutyronitrile, azobisisovaleronitrile, etc.). Of these, t-butyl peroxybenzoate and methyl ethyl ketone peroxide are preferable from the viewpoint of stability and reactivity of the adhesive.

The usage-amount of a thermosetting catalyst is 5% or less normally based on the total weight of the adhesive agent of this invention, Preferably it is 0.1 to 3%.

The adhesive of the present invention can be an adhesive (coating liquid) containing a solvent as necessary in order to adjust the viscosity to be suitable for coating during coating. The amount of the solvent used is usually 2,000% or less, preferably 10 to 500%, based on the total weight of the adhesive. The viscosity of the coating liquid is the temperature at the time of use (usually 5 to 60 ° C.), usually 200 to 500,000 mPa · s, preferably 500 to 10,000 mPa · s from the viewpoint of stable coating without foaming. is there. The viscosity can be measured as described below.

The solvent is not particularly limited as long as it dissolves the resin component in the adhesive. Specifically, aromatic hydrocarbons (C7-10, such as toluene, xylene and ethylbenzene), esters or ether esters (C4-10, such as ethyl acetate, butyl acetate and methoxybutyl acetate), ethers (C4-10, such as Diethyl ether, tetrahydrofuran, monoethyl ether of EG, monobutyl ether of EG, monomethyl ether of PG and monoethyl ether of DEG), ketones (C3-10, eg acetone, methyl ethyl ketone, methyl isobutyl ketone, di-n-butyl ketone and cyclohexanone) ), Alcohols (C1-10, such as methanol, ethanol, n- and i-propanol, n-, i-, sec- and t-butanol, 2-ethylhexyl alcohol and benzyl alcohol). Coal), amides (C3-6, such as dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, etc.), sulfoxides (C2-4, such as dimethylsulfoxide), water, and mixed solvents of two or more of these. It is done.
Of these solvents, esters, ketones and alcohols having a boiling point of 70 to 100 ° C. are preferred, and ethyl acetate, methyl ethyl ketone, i-propanol and mixtures thereof are more preferred.

The adhesive of the present invention can be prepared by blending the above-mentioned (A) to (D) and, if necessary, the above-mentioned other components [(E), (F), thermosetting catalyst, solvent, etc.]. it can.

Next, the optical sheet of the present invention comprises a resin layer (I) having fine protrusions on the surface, an adhesive intermediate layer (II) obtained by curing the adhesive of the present invention, and a transparent material that imparts rigidity and smoothness. It consists of three layers of the base material layer (III).
Moreover, the manufacturing method of the optical sheet of this invention applies the said adhesive agent on the transparent base material layer (III) which provides rigidity and smoothness, and the resin layer (I) which has a fine protrusion on the surface. The back surface is laminated on the adhesive, and then the adhesive is cured by ultraviolet irradiation to form the adhesive intermediate layer (II).
That is, if necessary, the adhesive of the present invention is diluted with a solvent, coated on the transparent substrate layer (III) to give rigidity and smoothness, dried as necessary, and then finely coated on the surface. An optical sheet comprising three layers (I), (II), and (III), wherein a resin layer (I) having various protrusions is bonded and then cured by ultraviolet irradiation to form an adhesive intermediate layer (II) Is manufactured.

The resin of the resin layer (I) is not particularly limited, but is usually a transparent resin having a Mn of 100,000 to 10,000,000, such as polyethylene terephthalate, polymethyl methacrylate, polycarbonate, triacetyl cellulose, propylated or butylated acetyl. Examples thereof include cellulose, cycloolefin copolymer (ethylene-norbornene copolymer, etc.) and polymethyl methacrylate-styrene copolymer resin.
These shapes may be either plate-like or film-like, but a film shape having a thickness of 0.05 to 5 mm is preferable from the viewpoint of productivity.
As a forming method of (I), for example, a method of injecting or extruding the above resin into a mold having fine recesses over the entire surface of the mold; for example, UV curing to a mold having fine recesses Examples include a method in which a resin (including those used in the examples described later) is cast, a transparent resin film of the resin for (I) is placed on the resin, and UV irradiation is performed from above. In the latter case, the transparent resin film side [the back surface of the resin layer (I)] is preferably bonded to the adhesive.

Examples of the material for the transparent substrate layer (III) include the resin (I), glass, quartz and the like. The shape of (III) is preferably a plate having a thickness of 1 to 50 mm from the viewpoint of imparting rigidity and smoothness to the optical sheet.

In the application of the adhesive of the present invention, normally used apparatuses such as a coating machine [bar coater, gravure coater, roll coater (size press roll coater, gate roll coater, etc.), air knife coater, spin coater, blade coater, etc. ] Can be used.
The film thickness after coating (film thickness after drying) is usually 0.5 to 300 μm, and the preferable upper limit is 250 μm from the viewpoint of drying properties and curability, and the preferable lower limit is 1 μm from the viewpoint of curability and transparency.

When the adhesive of the present invention is used after being diluted with a solvent, it is preferably dried after coating. Examples of the drying method include hot air drying (such as a dryer). The drying temperature is usually 10 to 200 ° C., the upper limit is preferably 150 ° C. from the viewpoint of deformation of the resin layer (I), and the lower limit is preferably 30 ° C. from the viewpoint of the drying speed.

When the adhesive is cured by ultraviolet irradiation, a known ultraviolet irradiation device [for example, Eye Grandage, manufactured by Eye Graphic Co., Ltd.] or the like can be used. The dose of the ultraviolet radiation is typically 10~10,000mJ / cm ^2, a preferred upper limit of a flexible point of view of the cured product, 5,000 mJ / cm ^2, preferably lower from the viewpoint of curability of the composition, 100 mJ / cm ² .

The optical sheet of the present invention can be used for, for example, a prism sheet, a collimator lens, a Fresnel lens, a lenticular lens, a light reflection lens, a hologram, an AR sheet, an AG sheet, an LR sheet, and the like. The adhesive of the present invention is useful for producing the optical sheet.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these.

Production Example 1
In a reaction vessel equipped with a stirrer, a condenser and a thermometer, PTMG [Mn 1,000, manufactured by Mitsubishi Chemical Corporation, trade name: PTMG-1000] 100 parts, IPDI 33.3 parts and bismuth tri (2-ethylhexa) as a catalyst. Noate) (2-ethylhexanoic acid 50% solution) 0.05 parts, reacted at 100 ° C. for 4 hours, then added 11.6 parts of 2-hydroxyethyl acrylate, reacted at 100 ° C. for 6 hours and urethane An acrylate (A-1) was obtained.

Production Example 2
In a reaction vessel similar to Production Example 1, 100 parts of PEG [Mn2,000, manufactured by Sanyo Chemical Industries, Ltd., trade name: Newpol PEG-2000] and 26.2 parts of hydrogenated MDI were charged, and reacted at 110 ° C. for 4 hours. After that, 11.6 parts of 2-hydroxyethyl acrylate and 0.03 part of bismuth tris (2,2,6,6-tetramethyl-3,5-heptanedionate) as a catalyst were added and the mixture was heated at 80 ° C. for 4 hours. Reaction was performed to obtain urethane acrylate (A-2).

Production Example 3
In a reaction vessel similar to Production Example 1, PTMG [Mn 2,000, manufactured by Mitsubishi Chemical Corporation, trade name: PTMG-2000] 100 parts, BD 4.9 parts, hydrogenated MDI 39.3 parts and 2-hydroxyethyl acrylate 11 .6 parts was charged and mixed uniformly, then 0.05 parts of bismuth tris (2,2,6,6-tetramethyl-3,5-heptanedionate) was added as a catalyst and reacted at 80 ° C. for 6 hours to obtain urethane. An acrylate (A-3) was obtained.

Comparative production example 1
In a reaction vessel similar to Production Example 1, polycaprolactone diol [Mn 2,000, manufactured by Daicel Chemical Industries, Ltd., trade name: Plaxel PCL-220] 100 parts, IPDI 22.2 parts and 2-hydroxyethyl acrylate 11.6 parts After charging and mixing uniformly, 0.05 parts of bismuth tris (2,2,6,6-tetramethyl-3,5-heptanedionate) was added as a catalyst and reacted at 80 ° C. for 6 hours to obtain urethane acrylate (A- 4) was obtained.

Comparative production example 2
In the same reaction vessel as in Production Example 1, polyester diol [Mn 1,000, manufactured by Sanyo Chemical Industries, Ltd., trade name: Sanester No. 22] 100 parts, 25.2 parts of hexamethylene diisocyanate and 11.6 parts of 2-hydroxyethyl acrylate were charged and mixed uniformly, and then bismuth tris (2,2,6,6-tetramethyl-3,5-heptanedio as a catalyst). Nate) 0.05 part was added and reacted at 80 ° C. for 6 hours to obtain urethane acrylate (A-5).

Mn and the number of colors (Hazen) of urethane acrylates (A-1) to (A-5) obtained in Production Examples 1 to 3 and Comparative Production Examples 1 and 2 were measured as follows. The results are shown in Table 1.
(1) Mn
It calculated | required as a polystyrene conversion value measured by GPC method using GPC measuring apparatus [HLC-8220, the Tosoh Corporation make], column (TSK-gel Super H).
(2) Number of colors (Hazen)
It measured according to JIS K0071. In addition, it shows that coloring degree is so large that the said value is large.

Reference Example 1, Examples 2, 3, Reference Example 4, Example 5 , Comparative Examples 1-6
(1) Preparation of adhesives (A-1) to (A-5) obtained above and other components were blended according to the weight ratio shown in Table 2 to obtain an adhesive.

(2) Production of optical sheet Using the adhesive obtained above, an optical sheet was produced by the following procedure.
1) Production of resin layer (I) having fine protrusions on the surface In a blending container equipped with a stirring device, (A-1) 50 parts, 3-phenoxy-2-hydroxypropyl acrylate [manufactured by Toagosei Co., Ltd., Product name: Aronix M-5710], 30 parts, EO-modified (added mole number 4) bisphenol A diacrylate [manufactured by Sanyo Chemical Industries, Ltd., trade name: Neomer BA-641] and 2-hydroxy-2-methyl 3 parts of -1-phenylpropan-1-one [manufactured by Ciba Specialty Chemicals Co., Ltd., trade name: Darocur 1173] was charged and uniformly mixed to prepare a UV curable resin. This was coated on a mold having fine recesses, and a PET film [thickness 75 μm, manufactured by Toray Industries, Inc., trade name: Lumirror U12 # 75] was placed thereon, and bubbles were pushed out by being sandwiched between nip rollers. Later, ultraviolet irradiation device [Eye Grandage, made by Eye Graphic Co., Ltd. The irradiation lamp is a metal halide lamp. same as below. The PET film [resin layer (I)] having fine protrusions was obtained by irradiating ultraviolet rays from the surface of the PET film at 1,000 mJ / cm ² and then releasing from the mold.
2) Production of optical sheet On the methyl methacrylate-styrene copolymer plate [thickness 2 mm, manufactured by Dainippon Ink & Chemicals, Inc., trade name: Clearpact TI-300] [transparent substrate layer (III)] After coating the adhesive obtained in step 1 (after drying) to a thickness of 100 μm, the PET film having fine protrusions produced in 1) on the coating side [resin layer (I) ] Were bonded together with a flat surface as an adhesive surface, and air was pushed out by sandwiching them with a nip roller. Thereafter, using an ultraviolet irradiation device, ultraviolet rays were irradiated from the side of the copolymer plate at 1,000 mJ / cm ² to form an adhesive intermediate layer (II) to obtain an optical sheet.

(Test method)
The physical properties and performance of the adhesive and optical sheet obtained above were evaluated by the following methods. The results are shown in Table 3.
(I) Viscosity The viscosity of the adhesive obtained above at 25 ° C. was measured using a BL type viscometer [manufactured by Tokyo Keiki Co., Ltd.].
(Ii) Refractive index The adhesive obtained as described above was applied with a roll coater to form a film having a thickness of 50 μm, and a cured product was obtained by irradiation with ultraviolet rays at 1,000 mJ / cm ² . The refractive index of the cured product at 25 ° C. was measured using an Abbe refractometer.
(Iii) Transmittance The adhesive obtained above was applied with a roll coater to form a film having a thickness of 50 μm, and ultraviolet rays were irradiated at 1,000 mJ / cm ² to obtain a cured product. The transmittance of the cured product at 25 ° C. was measured using a spectrophotometer [UV-2500PC, manufactured by Shimadzu Corporation].

(Iv) Adhesiveness Adhesion between cured adhesive [adhesive intermediate layer (II)] and methyl methacrylate-styrene copolymer plate [transparent substrate layer (III)] or PET film [resin layer (I)] In order to reach the inside of the (I) layer from the surface side of the (III) layer of the optical sheet obtained above, put a grid (10 × 10) in a width of 1 mm with a knife, (III ) A cellophane tape was applied to the surface side of the layer and peeled 90 degrees. At this time, the peeled state of the cured product (adhesive resin) from the copolymer plate or PET film was evaluated according to the following criteria.
(Evaluation criteria) ○ The grid pattern does not peel at all
X One or more grids peel off (v) Foaming The presence or absence of bubbles in the optical sheet obtained above was measured visually.
(Evaluation criteria) ○ No bubbles
× There are bubbles

(Vi) Haze The haze of the optical sheet obtained above was measured with a total light transmittance measuring device [manufactured by BYK Gardner, trade name: haze-gard dual]. In addition, it shows that transparency is so low that the said value is large.
(Vii) Light resistance A fade meter test (JIS B 7751) of the optical sheet obtained above was performed for 200 hours, and the optical sheet before and after the test was used to measure a colorimeter [multi-light source spectrocolorimeter [Suga Test Instruments Co., Ltd. ), Product name: C2]], and the yellow index (YI) was measured. In addition, it shows that coloring degree is so large that the said value is large and light resistance is low. Further, the difference (ΔYI) in yellow index before and after the test was obtained by calculation.

From the above results, the UV curable adhesive for forming an optical sheet of the present invention is excellent in adhesiveness, transparency and light resistance. Therefore, an optical sheet using the adhesive may have excellent characteristics as well. Recognize.

The adhesive intermediate layer obtained by curing the adhesive of the present invention is required to have transparency and light resistance because it has good transparency, excellent light resistance, and good adhesion to plastic, glass and the like. It is suitably used for applications such as optical sheets. In addition, the method for producing an optical sheet of the present invention is excellent in productivity because of its rapid curing, and is extremely useful industrially. The resulting optical sheet is excellent in optical properties, and thus can be made finer. Furthermore, since it is excellent in mechanical strength and strong, it is possible to reduce the weight and thickness of liquid crystal displays and projection TVs.

Claims (6)

An ultraviolet curable adhesive for forming an optical sheet comprising the following (A) to (D),
(A) Urethane (meth) acrylate (B) isobornyl (meth) acrylate formed from polyether polyol (a1), alicyclic polyisocyanate (a2) and hydroxyl group-containing (meth) acrylate (a3) , dicyclopentadiene ( (Meth) acrylate, norbornene (meth) acrylate or a mixture thereof (C) monofunctional (meth) acrylate represented by the following general formula (1) R—Ph—O (CH ₂ CH ₂ O) nCOCR′═CH ₂ (1 )
(In the formula, R represents H or a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms, R ′ represents H or a methyl group, Ph represents a phenylene group, and n represents an integer of 1 to 4)
(D) selected from the group consisting of 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and methylphenylglyoxyester The number average molecular weight of one or more photopolymerization initiators (A) is 500-3100,
The weight ratio of (D) based on the total weight of (A) to (D) is 0.3 to 0.9%,
An ultraviolet curable adhesive for forming an optical sheet, which does not contain any of acryloylmorpholine, dimethylacrylamide, diethylacrylamide and diisopropylacrylamide. The adhesive according to claim 1, wherein (A) is a urethane (meth) acrylate formed using an organic bismuth urethanization catalyst. The adhesive according to claim 1 or 2, wherein the weight ratio based on the total weight of (A) to (D) is (A) 20 to 69%, (B) 10 to 50%, and (C) 20 to 60%. . The adhesive according to any one of claims 1 to 3, wherein a weight ratio of (B) / (C) is 0.3 / 1 to 1.5 / 1. A resin layer (I) having fine protrusions on the surface, an adhesive intermediate layer (II) obtained by curing the adhesive according to any one of claims 1 to 4, and a transparent substrate layer imparting rigidity and smoothness ( An optical sheet consisting of three layers of III). The adhesive according to any one of claims 1 to 4 is coated on the transparent base layer (III) imparting rigidity and smoothness, and the back surface of the resin layer (I) having fine protrusions on the surface thereof An optical system comprising three layers (I), (II) and (III), wherein the adhesive is cured by ultraviolet irradiation and then the adhesive is cured to form an adhesive intermediate layer (II). Sheet manufacturing method.