JP5706994B1 - Adhesion method with excellent light-blocking curability - Google Patents

Abstract

An ultraviolet curable adhesive composition capable of effectively curing a light shielding portion to which ultraviolet rays do not reach, and a coating, curing, and bonding method using the same are provided. A (meth) acrylic monomer having a radical polymerizable group, which is produced from a (meth) acrylic monomer in one step and obtained by polymerization of the monomer and radical polymerizable double bond modification in the step. Resin (A): 10 to 90 parts by mass, vinyl compound (B) having a radical polymerizable double bond: 10 to 90 parts by mass, and photopolymerization initiator (C): 0.01 to 10 parts by mass It is the adhesive composition characterized by doing. Since this adhesive composition is delayed curable, the coating composition is irradiated with ultraviolet rays to semi-cure the adhesive composition, and other members can be laminated via the semi-cured adhesive layer. It can be applied to the member adhesion of the light-shielding part that does not reach. [Selection] Figure 1

Description

The present invention relates to a contact Chakuhoho. For more information, it can be effectively cured light shielding portion ultraviolet does not reach to a bonding method using an ultraviolet curable adhesive composition that have a delayed curability.

  A cover lens on a liquid crystal display screen is generally provided with a frame made of a colored layer (hereinafter referred to as “bezel”) for the purpose of design and the like. Since this colored layer has many colored layers stacked in order to ensure concealability, it is difficult for ultraviolet rays to pass through the colored layer. Therefore, although it is easy to cure the portion irradiated with ultraviolet rays, there is a problem that the curing reaction does not proceed sufficiently in the colored light-shielding portion.

  There are cases where the light-shielding part that is not sufficiently cured by ultraviolet rays has problems such as insufficient physical properties, generation of odors and bubbles due to residual monomers, and outflow of unreacted components to the outside of the display frame over time. In addition, display failure or peeling of the display over time may occur. Various methods have been proposed to solve these problems.

  For example, (1) a method using a heat or moisture curable adhesive (Patent Document 1, etc.), (2) a method using a highly sensitive photoinitiator or a highly reactive UV curable component, and (3) a lot of ultraviolet rays. A method of irradiating from an angle and eliminating a light-shielding part (Patent Document 2 etc.), (4) Utilizing time-dependent curing of a photo-cationic polymerization curing reaction using an epoxy resin as a cured resin component, For example, a method of bonding with a member having the.

  However, when the optical member is a plastic or polarizing film or includes an electronic component, the method (1) by thermosetting may cause deformation or breakage of the member due to heat. Furthermore, in order to make the reaction by heat sufficiently proceed, generally a reaction time of 1 hour or more is required, and there is a disadvantage that the productivity is remarkably lowered. In addition, the moisture curing method generally requires humidity, a curing accelerator (catalyst) and heat in order to accelerate curing. However, in bonding substrates, there is a drawback that the adhesive is hardly affected by humidity because it is in a nearly closed system, and the curing reaction is difficult to proceed. Further, since a curing accelerator (catalyst) is mixed immediately before coating for promoting curing, there is a problem that air bubbles are mixed. There is also a concern of thickening during storage.

  The method (2) using a high-sensitivity photoinitiator is effective for curing with weak ultraviolet light leaking from a gap, but the curing reaction does not proceed because there is almost no ultraviolet light transmitted from the front of the bezel. In addition, since an initiator that absorbs long-wavelength ultraviolet rays is used, the problem of yellowing also occurs.

  In the method (3), for example, in the case of bonding a cover glass of a liquid crystal display and a liquid crystal module, ultraviolet irradiation from the front and side surfaces of the cover glass is effective, but ultraviolet irradiation from the liquid crystal module side that is the back surface is effective. There is no effect.

  The method (4) is an effective method in that it is not affected by the light-shielding part, but the photocationic polymerization initiator that serves as the initiator for the curing reaction has a problem that it generates an acid upon irradiation with light. The acid acts on the epoxy group and cationic polymerization curing starts. On the other hand, when the bonding member contains a metal material such as ITO, the acid causes corrosion. As a result, in touch sensor applications and the like, disconnection occurs due to corrosion of ITO, causing a problem of malfunction.

JP 2005-281494 A JP 2004-012664 A

The present invention has been made in view of the above circumstances, purple coating the outside line is used effectively hardened to possible ultraviolet curable adhesive composition shielding portion is not reached, curing, bonding method The purpose is to provide.

  In order to solve the above-mentioned problems, the present inventors have intensively studied an acrylic polymer having a radical polymerizable group. As a result, a (meth) acrylic resin having a radically polymerizable group is generally obtained by a two-step reaction of a step of polymerizing an acrylic monomer and a step of introducing a (meth) acryloyl group into the obtained acrylic polymer. However, only a (meth) acrylic resin having a radical polymerizable group obtained by carrying out the process up to double bond modification in one step by high temperature polymerization or high temperature high pressure polymerization has delayed curing properties. Heading and completed the present invention

That is, the present invention provides a method of bonding members using ultraviolet curable adhesive, and irradiation and coating step of coating at least one of the members a coating solution consisting of the following adhesive composition, the ultraviolet to the coating solution An adhesive method including a curing step of semi-curing the adhesive composition and a bonding step of laminating other members via the semi-cured adhesive layer is provided.

A (meth) acrylic resin (A) having a radical polymerizable group, which is produced from a (meth) acrylic monomer in one step and obtained by polymerization of the monomer and radical polymerizable double bond modification in the step. : 10 to 90% by mass,
Vinyl compound (B) having a radically polymerizable double bond: 10 to 90% by mass,
And photopolymerization initiator (C): 0.01 to 10% by mass,
An adhesive composition containing

The adhesive composition has a cured product having an elongation (25 ° C.) of 50% or more and a storage elastic modulus (25 ° C.) of 1 × 10. ⁷ It is preferable that Pa or less and a cure shrinkage rate are 5% or less.

Furthermore, this invention provides the adhesion method which provided the thermosetting process in said adhesion method.

According to the bonding method of the present invention, the adhesive composition can be cured at room temperature, and even when used for a light-shielding portion where ultraviolet rays do not reach, deformation or breakage of a member like a thermosetting adhesive The members can be bonded together without causing any problems. Even when an optical member or the like having a light-shielding portion is bonded, an unreacted component does not flow out of the display frame or generate bubbles, so that a high-quality image display device that does not cause display defects or peeling is obtained. be able to. Since the cured product has high transparency and is excellent in moisture resistance, water resistance and flexibility, it is useful as an adhesive for various transparent members or non-transparent members.

It is explanatory drawing of the adhesion method of the member which has a light-shielding part.

  The adhesive composition of the present invention is produced from a (meth) acrylic monomer in one step, and has a radical polymerizable group obtained by polymerization of the monomer and radical polymerizable double bond modification in the step. It contains a (meth) acrylic resin (A), a vinyl compound (B) having a radical polymerizable double bond, and a photopolymerization initiator (C).

[(Meth) acrylic resin (A) having radical polymerizable group]
In the above-mentioned adhesive composition, the (meth) acrylic resin having a radical polymerizable group as the component (A) is used as a component that develops light-shielding part curability. In other words, radicals generated from (meth) acrylic resins having radical polymerizable groups are generated from polymers in which (meth) acryloyl groups are introduced into acrylic polymer in two steps, (meth) acrylic monomers, and vinyl monomers. It is stable compared to radicals that do. Therefore, the crosslinking reaction with the vinyl compound (B) having a radical polymerizable double bond can be suppressed, and an ultraviolet curable adhesive composition having delayed curing can be obtained.

The (meth) acrylic resin (A) having a radically polymerizable group reacts with a (meth) acrylic monomer in one step, thereby causing polymerization of the monomer and radical polymerizable double bond modification in this step. can get. The kind of (meth) acrylic monomer is not particularly limited.
The reaction conditions for the above-mentioned one step are desirably high temperature or high temperature and high pressure. The reaction is generally performed in a solvent using a polymerization initiator and a chain transfer agent. The reaction temperature is 200 ° C. or higher, preferably 230 to 290 ° C., and dibutyl peroxide, azobisisobutyronitrile, etc. By performing a radical polymerization reaction using a radical initiator, the molecule is cut at the ceiling temperature, and a radical polymerizable double bond is formed at the terminal. More preferably, the amount of the polymerization initiator and chain transfer agent used is 1% by mass or less based on the total amount of monomers to be polymerized, and the reaction is carried out at a high temperature or high temperature and high pressure with almost no use.

As a method for producing a (meth) acrylic resin having a radical polymerizable group, for example, one or a mixture of two or more compounds selected from alkyl (meth) acrylates having 1 to 18 carbon atoms as (meth) acrylic monomers Alternatively, there is a method in which a mixture of these and a styrenic monomer is used and reacted in one step. As a result, a (meth) acrylic resin having a non-functional radically polymerizable group having an unsaturated bond at the terminal is obtained.
As another production method, for example, as a (meth) acrylic monomer, one or a mixture of two or more compounds selected from alkyl (meth) acrylates having 1 to 18 carbon atoms, or a mixture of these and a styrenic monomer There is a method in which (meth) acrylate or (meth) acrylic acid having a functional group selected from glycidyl group, hydroxyl group and silyl group is used and reacted in one step. As a result, a (meth) acrylic resin having a hydroxyl group-containing type having a terminal unsaturated bond, a carboxyl group-containing type, an epoxy group-containing type, or an alkoxysilyl group-containing type radical polymerizable group is obtained.
As said C1-C18 alkyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl ( Examples include meth) acrylate and isostearyl (meth) acrylate.
In this case, the radical polymerizable group includes an unsaturated group represented by CH ₂ ═C (COOR) —. Here, R is an alkyl group having 1 to 12 carbon atoms. The number of double bonds is about one for one polymer chain. The mass average molecular weight (Mw) of the (meth) acrylic resin having a radical polymerizable group is preferably in the range of 3,000 to 20,000, and is preferably liquid at room temperature, but not liquid at room temperature ( For example, the flaky form can be used by dissolving in a vinyl compound (B) having a radical polymerizable double bond to exhibit a retarding property.

The (meth) acrylic resin (A) having the above radical polymerizable group is commercially available from Toagosei Co., Ltd. under the trade name ARUFON. Specific examples of the (meth) acrylic resin (A) having a radical polymerizable group include non-functional group types ARUFON UP1000, UP1010, UP1020, UP1061, UP1080, UP1110, UP1150, UP1170, UP1190, UP1500; Types ARUFON UH2000, UH2041, UH2170, UH2190; Carboxyl group-containing ARUFON UC3000, UC3080, UC3900, UC3920, UC3510, UF5080, UF5022; Epoxy group-containing types UG4010, UG4035, UG4040, UG4040, UG4040, UG4040, UG4040, UG4040 For example, US6100 and US6170 which are contained types can be mentioned. These (meth) acrylic resins may be used alone or in combination of two or more. Among the (meth) acrylic resins having the above radical polymerizable group, from the viewpoint of high delayed curability, a non-functional group type and a hydroxyl group-containing type (meth) acrylic resin are preferable.

The (meth) acrylic resin (A) having the above radical polymerizable group refers only to a compound produced by a one-step reaction, and an acrylic polymer having a terminal carboxyl group is produced in the first step, and the second step. A polymer (for example, macromonomer AA-6, AB-6, AN-6S, AS-6 (manufactured by Toagosei Co., Ltd.)) in which one (meth) acryloyl group is introduced at the molecular terminal of the acrylic polymer; In the first step, an acrylic polymer having a terminal carboxyl group or a glycidyl group is produced, and in the second step, a (meth) acryloyl group is introduced into the skeleton of the acrylic polymer (for example, Unidic (manufactured by DIC Corporation), Acrylic resin acrylate (manufactured by Hitachi Chemical Co., Ltd.), 8KX series (manufactured by Taisei Fine Chemical Co., Ltd.), Olester RA3057 (Mitsui) Manabu Ltd.)) does not contain a polymer produced in two steps, such as. The polymer produced by these two steps does not exhibit delayed curability.

The content ratio of the (meth) acrylic resin having a radical polymerizable group is 10 to 90 % by mass, preferably 25 to 75 % by mass, based on the entire adhesive composition. If it is less than 10 % by mass, the delayed curing property is not sufficiently exhibited, so that the curing proceeds without going through a semi-cured state, and there is a problem that the bonding after UV irradiation cannot be performed. On the other hand, when it exceeds 90 % by mass, generation of stable radicals derived from the (meth) acrylic resin having a radical polymerizable group becomes excessive, resulting in poor curing.

[Vinyl compound having a radically polymerizable double bond (B)]
In the adhesive composition of the present invention, the vinyl compound having a radical polymerizable double bond as the component (B) can improve the adhesive strength of the cured product by a crosslinking reaction with the component (A). It is an ingredient. In addition, there is an effect of diluting the component (A). These vinyl compounds may be used independently and 2 or more types may be used together.

As a specific example of the component (B), as a vinyl compound having one radical polymerizable double bond in one molecule, for example,
Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) (Meth) acrylates such as alkyl acrylates having 1 to 18 carbon atoms such as acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate;
Of 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. hydroxyl group-containing (meth) acrylates such as ε-caprolactone adduct, 2-hydroxyethyl (meth) acrylate and γ-butyrolactone adduct;
Unsaturated dibasic acids such as (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid;
Carboxyl group or alkoxycarbonyl group-containing vinyl compounds such as dialkyl esters such as dimethyl malate and dimethyl fumarate;
Acid anhydride-containing vinyl compounds such as maleic anhydride and itaconic anhydride;
Epoxy group-containing vinyl compounds such as glycidyl (meth) acrylate;
Aromatic vinyl compounds such as styrene, α-methylstyrene and vinylstyrene;
Amino group-containing vinyl compounds such as dimethylaminomethyl (meth) acrylate, diethylaminomethyl (meth) acrylate, dimethylaminopropylacrylamide;
Can be mentioned.

  Among these (B) component (meth) acrylates, those having 4 to 8 carbon atoms (meth) acrylic acid alkyl esters or (meth) acrylic acid cycloalkyl esters having a cyclohexane ring ( The meth) acrylic acid cycloalkyl ester has a great dilution effect. Of these, acrylic acid cycloalkyl esters (CHA) such as isobornyl (meth) acrylate are preferred because they have a low glass transition point and are flexible.

  In addition to the above, (meth) acrylonitrile, vinyl acetate, vinyl propionate, butadiene, isoprene, chloroprene and the like can be exemplified.

  Specific examples of the component (B) include vinyl compounds having two radical polymerizable double bonds in one molecule, such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (Meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene oxide modified Bisphenol A type di (meth) acrylate, propylene oxide modified bisphenol A type di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerin di (meth) acrylate , Pentaerythritol di (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether (meth) acrylate, hydroxypivalic acid-modified neopentyl glycol di (meth) acrylate.

  Specific examples of the component (B) include vinyl compounds having three or more radical polymerizable double bonds in one molecule, such as trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, penta Examples include erythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate. In addition, isocyanuric acid derivatives and the like can also be used.

  Besides the vinyl compound, urethane-modified (meth) acrylate, polyester-modified (meth) acrylate, and epoxy-modified (meth) acrylate can also be used.

The vinyl compound having a radical polymerizable double bond is a component having a role of adjusting the degree of delayed curability depending on the blending ratio with the radical polymerizable (meth) acrylic resin (A). The content ratio of the component (B) is 10 to 90 % by mass, preferably 25 to 75 % by mass, based on the entire adhesive composition. If it is less than 10 % by mass, the curing rate becomes slow, which causes poor curing. On the other hand, if it exceeds 90 % by mass, the curing rate is too high so that the adhesive does not spread out and the bonding after UV irradiation cannot be performed.

[Photoinitiator (C)]
As the photopolymerization initiator (C), any known photopolymerization initiator can be used as long as it initiates radical polymerization upon irradiation with ultraviolet rays, and includes benzoin, benzophenone, benzyl, acetophenone, quinone, and thioxanthone. And known compounds such as phenylglyoxylic acid series.

  Specific examples of the photopolymerization initiator include benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone, p-methoxybenzophenone, o-benzoylbenzoic acid, o-benzoylbenzoic acid Benzophenone compounds such as methyl acid, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone; benzyl compounds such as benzyl, 4,4′-dimethoxybenzyl; acetophenone, 2, Acetates such as 2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one Enone compounds; quinone compounds such as 2-ethylanthraquinone, 2-t-butylanthraquinone, 1,4-dimethylanthraquinone, camphorquinone; thioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, Examples include thioxanthone compounds such as 2,4-diethylthioxanthone and 2-chlorothioxanthone; phenylglyoxylic acid compounds such as methylphenylglyoxylate and ethylphenylglyoxylate. These initiators may be used independently and 2 or more types may be used together.

(C) content of the component is 0.01 to 10 mass% is preferably the entire adhesive composition, based, more preferably 0.25 to 8% by weight, particularly preferably 1 to 5 wt%. If it contains in such a range, the sclerosis | hardenability and adhesive strength of an adhesive composition will not deteriorate, and the water resistance and durability of hardened | cured material may not fall by the increase in an ionic substance.

[Non-Radical Polymerizable Flexible Component (D)]
In the adhesive composition of the present invention, a non-radically polymerizable flexible component (D) can be blended for the purpose of improving the flexibility of the cured product.
Specific examples of the non-radically polymerizable flexible component (D) include acrylic resins, polyester diols, polyether diols, polycarbonate diols or modified products thereof that do not have a radical polymerizable group. These flexible components are effective for reducing cure shrinkage and lowering the storage elastic modulus. These compounds can be used alone or in combination of two or more.

  A typical example of the acrylic resin having no radical polymerizable group is the Actflow (Soken Chemical Co., Ltd.) series. As specific examples, UMB-1001, UMB-1003, UMM-1001 as functional hydroxyl types, polyfunctional hydroxyl type UT-1001, monofunctional alkoxysilyl type NE-1000, polyfunctional carboxyl type CB- as polyfunctional hydroxyl types. 3060, CB-3098, CBB-3098 and the like.

Examples of the polyester diol include condensed polyester diols obtained by esterification reaction of dibasic acid and diols, or lactone polyester diols obtained by ring-opening polymerization of lactone with diols. .
The dibasic acid used in the condensed polyester diols is preferably an aliphatic or alicyclic dibasic acid having no aromatic ring, such as oxalic acid, succinic acid, glutaric acid, pimelic acid, adipic acid. , Azelaic acid, sebacic acid, dodecanedicarboxylic acid, cyclopentanedicarboxylic acid, cyclohexanedicarboxylic acid, fumaric acid, maleic acid and the like. These dibasic acids may be used alone or in combination of two or more.
The diol used in the condensed polyester diol is preferably a diol having no aliphatic or alicyclic aromatic ring, such as ethylene glycol, 1,2-propanediol, 1,3-propane. Diol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentane Examples include diol, 1,8-octanediol, diethylene glycol, dipropylene glycol and the like. These diols may be used alone or in combination of two or more.
Lactone-based polyester diols can be obtained by ring-opening polymerization of β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, etc. to a low molecular diol. Examples of the low molecular weight diol include the same diols used in the above-mentioned condensed polyester diols.

  Of these polyester diols, condensed polyester diols obtained from dibasic acids and diols are preferred. Specifically, “Nipporan” series of Nippon Polyurethane Industry Co., Ltd., manufactured by Kawasaki Kasei Kogyo Co., Ltd. Commercial products such as “Maximol” series and “Polylite” series manufactured by DIC Corporation may be mentioned.

  Examples of the polyether diol include polyether diols obtained by a reaction between a compound having two active hydrogens and an alkylene oxide. Here, examples of the compound having two active hydrogens include water, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and the alkylene oxide includes ethylene. Examples thereof include oxide, propylene oxide, and tetrahydrofuran.

  Alkylene oxides may be used alone or in combination of two or more. Specific examples of polyether diols include polyethylene glycol using ethylene oxide alone, polypropylene glycol using propylene oxide alone, tetrahydrofuran And polyethylene glycol-polypropylene glycol block copolymer using ethylene oxide and prepylene oxide in combination.

  As polycarbonate diol, the polycarbonate diol obtained by transesterification with a dialkyl carbonate and diol is mentioned, for example.

  The dialkyl carbonate is preferably an aliphatic or alicyclic dialkyl carbonate having no aromatic ring, and examples thereof include dimethyl carbonate, diethyl carbonate, di-n-butyl carbonate, and ethylene carbonate. As the diol, like the diol used in the polyester diol, an aliphatic or alicyclic diol having no aromatic ring is preferable. Specific examples include, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentane. Examples include diol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, and dipropylene glycol.

  Among these non-radical polymerizable flexible components (D), polyester diol is inferior in hydrolysis resistance, and polyether diol is inferior in water resistance. Therefore, acrylic resins and polycarbonate diols having no radical polymerizable group are more preferred. preferable.

The non-radically polymerizable flexible component (D) has a role of adjusting the hardness and cure shrinkage of the adhesive. Two or more of these can be blended. Preferred amount is from 5 to 70 mass%, more preferably from 5 to 30 mass%. Adhesive is hardened in less than 5 wt%, there are disadvantages curing shrinkage property which tends to occur a decrease in peeling and visibility to become large and exceeds 70 mass%, the non-reactive component is excessive, the curing This is likely to cause the problem of insufficient.

  The production method of the adhesive composition of the present invention is not particularly limited, and the above components (A), (B) and (C), and if necessary, the component (D) are blended, and if necessary, other additives. A predetermined amount is obtained by mixing and stirring until uniform. The viscosity of the adhesive composition is preferably 150 mPa · s or less at 25 ° C. in order to obtain a coating surface that can be used in the coating process, that is, a thin film and excellent smoothness.

  Examples of the additives include pigments for adjusting light transmittance and color tone, plasticizers, reinforcing agents, photosensitizers, light stabilizers, chain transfer agents, ultraviolet absorbers, antioxidants, and viscosity modifiers. , Tackifiers (tackifiers), foam stabilizers, antifoaming agents, antifungal agents, preservatives, and the like can be blended. These additives can be used alone or in combination as long as they do not impair the optical characteristics and curing characteristics.

  Moreover, in the adhesive composition of this invention, the thermal cationic polymerization initiator which generate | occur | produces an acid with a heat | fever can be mix | blended. Even when it is difficult to irradiate ultraviolet rays when curing the adhesive composition of the present invention, or when adhering portions that do not transmit ultraviolet rays, the adhesive composition may contain a thermal cationic polymerization initiator. For example, it can be cured by applying heat.

Examples of the thermal cationic polymerization initiator include benzylsulfonium salt, benzylammonium salt, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, and amine imide. These initiators can be easily obtained as commercial products. For example, Sun-Aid SI-60L, SI-80L, SI-100L (all manufactured by Sanshin Chemical Industry Co., Ltd.), Adeka Opton CP-66 CP-77 (all manufactured by ADEKA Corporation) and the like. The content ratio of the thermal cationic polymerization initiator is preferably in the range of 0.1 to 10 % by mass, more preferably 0.1 to 3 % by mass, based on the entire adhesive composition.

The adhesive composition of the present invention has a curing shrinkage of 5% or less, an elongation (25 ° C.) of a cured product obtained by curing by ultraviolet irradiation of 200% or more, and a storage elastic modulus (25 ° C.) of 1. It is preferable that it is 10 ⁷ Pa or less.

Thus, by adjusting the cure shrinkage rate to 5% or less, more preferably 3% or less, the internal stress accumulated when the adhesive composition is cured can be reduced, and the cured product can be reduced. It is possible to prevent distortion at the interface between the layer and the member to be bonded, and to suppress display unevenness and cured product peeling in an image display device or the like.
Moreover, by adjusting the elongation percentage (25 ° C.) of the cured product to 200% or more, the cured product can follow the thermal deformation of the glass plate, but the glass substrate and a plastic substrate such as polycarbonate resin or acrylic resin Considering the pasting together, the elongation (25 ° C.) of the cured product is preferably in the range of 200% to 400%.
Further, by adjusting the storage elastic modulus (25 ° C.) of the cured product to 1 × 10 ⁷ Pa or less, preferably 1 × 10 ⁵ to 1 × 10 ⁶ Pa, the cured product is cured when the adhesive composition is cured. The internal stress caused by the shrinkage can be reduced, and the cured product can follow the warp of the adherend.

  The adhesive composition of the present invention can be suitably used for the production of a laminate comprising a transparent glass plate or a plastic substrate, specifically, a laminate of a glass plate and a glass plate, a glass plate and a plastic. It can be used for the production of a laminate of a substrate, a laminate of a plastic substrate and a plastic substrate. Especially, it is preferable to use for the laminated body which uses a glass plate with high mechanical strength. Although the use of a laminated body is not specifically limited, The especially suitable use is an optical member. As a glass plate, what is used as a glass plate which clamps the liquid crystal of a liquid crystal cell, or a protective plate of a liquid crystal cell can be used preferably.

  Plastic base materials include translucent polycarbonate resin or acrylic resin (polymethyl methacrylate, etc.), polyethylene terephthalate (PET) resin, triacetyl cellulose (TAC) resin, cycloolefin polymer (COP) resin, and polynorbornene resin A plate-like, sheet-like, or film-like protective plate made of, for example, can be preferably used. It can also be preferably used for adhesion of transparent or non-transparent optical films such as an antireflection film, an antiglare film, a viewing angle control film, and an ITO film laminated on the front or back surface of the protective plate.

  Moreover, the adhesive composition of this invention can be used suitably also for adhesion | attachment with a polarizer and a protective film in manufacture of a polarizing plate. As the polarizer, for example, a plastic substrate made of a hydrophilic polymer such as a partially saponified product of polyvinyl alcohol is adsorbed with iodine or a dichroic dye and uniaxially stretched, or a dehydrated polyvinyl alcohol or a polysiloxane is used. Examples include a dehydrochlorinated product of vinyl chloride. Examples of the protective film include plastic films made of TAC resin, COP resin, polynorbornene resin, and the like.

  When the substrate is bonded using the adhesive composition of the present invention, a coating liquid comprising the adhesive composition of the present invention is applied to at least one of the bonding surfaces of the glass plate or the plastic substrate. An application process to be performed, a drying process (where volatile components are removed), if necessary, a lamination process in which another glass plate or a plastic substrate is laminated via the coating solution, and a translucent substrate in a bonded state. A laminated body can be manufactured with the adhesion | attachment method including the hardening process which hardens an adhesive composition by irradiating an ultraviolet-ray from the outside. A heat curing step may be provided after the curing step.

  When bonding the base material which has a light-shielding part using the adhesive composition of this invention, as shown in FIG. 1, the adhesive composition of this invention is attached to the bonding surface of the said glass plate or a plastic base material. A coating step of applying a coating solution composed of a product, a curing step of drying (removing volatile matter) if necessary, and then semi-curing the adhesive composition by irradiating the coating solution with ultraviolet rays, and a semi-cured state A laminated body can be manufactured by the adhesion | attachment method including the bonding process which laminates | stacks the base material which has a light-shielding part through an contact bonding layer. In order to accelerate the curing of the adhesive composition, it is preferable to provide a thermosetting step after the bonding step. You may implement an application | coating process and a hardening process simultaneously.

  As a coating method in the coating process, for example, a known method such as a roll coating method, a spray method, a dip method, a brush coating method, an ink jet method, or an electrostatic coating method may be used. As for the atmospheric temperature of an application | coating process, 15-30 degreeC is preferable. The thickness of the coating film is not particularly limited, but it is preferably applied so that the film thickness after curing is about 50 to 200 μm.

  In the bonding step, the base materials are overlapped via the coating solution, and both surfaces of the overlapped base materials are pressurized.

  As the ultraviolet light source in the curing process, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

The irradiation intensity is determined for each target adhesive composition and is not particularly limited. The light irradiation time to the adhesive composition is controlled for each adhesive composition to be cured, and is not particularly limited, but the integrated light amount represented by the product of the irradiation intensity and the irradiation time is 10 to 5,000 mJ. It is preferably set to be / cm ² . If the integrated light intensity is too small, the photocation polymerization initiator may not be sufficiently decomposed and the adhesive composition may be insufficiently cured. On the other hand, if the integrated light intensity is increased, the irradiation time becomes longer. This is disadvantageous for productivity improvement.

  The optical member formed by bonding using the adhesive composition of the present invention can minimize the influence of stress at the time of curing shrinkage on the glass or plastic substrate, and the optical member is hardly distorted or deformed. Does not occur. Therefore, for example, when the adhesive composition of the present invention is used for a polarizing plate, an image display device free from display unevenness can be provided, and an image display device excellent in durability that does not cause whitening or peeling of a cured product is provided. be able to.

  Furthermore, the adhesive composition of the present invention is also used as an adhesive that fills and bonds the space existing between the liquid crystal panel of the liquid crystal display device and the protective member, taking advantage of its transparency, flexibility and water resistance. be able to. For example, the present invention can be applied to various image display devices such as an organic EL device (sealing agent for organic EL elements) and a plasma display device (adhesion of a transparent plastic film and a conductive metal foil). Other than the image display device, it is also suitably used for optical members such as spectacle lenses, CD and DVD pickup lenses, automobile headlamp lenses, projector lenses, optical fibers, optical waveguides, optical filters, and optical disk substrates. In addition, it can also be used as an adhesive for flexographic printing plates, decorative sheets used for furniture, joinery, furniture, automobile interior materials, and semiconductor elements. Further, when the adhesive composition of the present invention is used for an application that does not require transparency, powders such as colloidal silica, talc, mica, calcium carbonate, titanium oxide, and clay, and glass are used as fillers. Fibers such as fiber, polyester fiber, rayon fiber, and nylon fiber may be added.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example and a comparative example, this invention is not limited only to a following example. In addition, “part” and “%” in the sentence are based on mass.

[Ultraviolet curing of a member having a light shielding part]
Production of a member having a light shielding part: A cover glass having a light shielding part was produced under the following conditions.
As the member, a glass plate having a size of 10 cm × 10 cm and a thickness of 1 mm was used. ORIGITZUKU # 100 Kuro (origin electric Co., Ltd. acrylic silicone paint) / hardening agent Polyhard G is mixed at a mixing ratio of 4/1, and it is coated to a thickness of 20 μm with a width of 2 cm along the edge of the glass plate. Then, a light shielding part was produced. At this time, the light transmittance of the light shielding portion was 0% in the range of 400 to 800 nm.

(Examples 1-7, Comparative Examples 1-10)
The components and amounts shown in Tables 1 and 2 were blended to prepare an adhesive composition. As the member, a glass plate having a size of 10 cm × 10 cm and a thickness of 1 mm was used.

[Lamination step]: The prepared adhesive composition is dropped on a cover glass having a light-shielding part, and UV irradiation (Fusion D bulb, integrated light quantity: 2,000 mJ / cm ² , maximum illuminance: 600 mW / cm ² ) Then, the other transparent member was bonded to obtain a test piece in which two members were bonded with an adhesive (Step 1).

(Example 8)
After performing the same bonding step (step 1) with the formulation of Example 7, heat curing was further performed at 60 ° C. for 30 minutes.

  The evaluation results are shown in Tables 1 and 2. From Tables 1 and 2, by blending the (meth) acrylic resin (A) having a predetermined amount of radical polymerizable group, wetting and spreading of the coating liquid after bonding can be maintained for a long time. An adhesive composition having high transparency, elongation properties, storage elastic modulus, and cure shrinkage properties and desired moisture resistance and boiling water resistance was obtained. Further, in the case of an adhesive composition that slowly cures, the desired light-shielding part curability could be obtained by thermosetting after UV irradiation (Example 8).

  On the other hand, when the (meth) acrylic resin (A) having a radical polymerizable group is not blended (Comparative Examples 1 to 6) and when the blending amount is small (Comparative Example 7), wetting and spreading of the coating liquid after bonding is performed. However, when the blending amount was large (Comparative Example 8), the wetting and spreading of the coating solution was good, but the curing rate was too slow, and there was a defect in production. When a (meth) acrylic resin having no radical polymerizable group (Comparative Example 9) and a macromonomer (Comparative Example 10) were blended, curing retardance was not exhibited.

[Details of ingredients in Tables 1 and 2]
UH2000: ARUFON UH-2000 (high temperature continuous bulk polymerized product with hydroxyl group, solvent-free, Mw: 11,000,
Glass transition point: -55 ° C, hydroxyl value: 20) (manufactured by Toagosei Co., Ltd.)
UP1080: ARUFON UP-1080 (High-temperature continuous bulk polymerized product with no functional group, no solvent, Mw: 6,000,
Glass transition point: -61 ° C (manufactured by Toagosei Co., Ltd.)
RA3057: Olestar RA3057, solvent-free acrylic resin acrylate (Mitsui Chemicals)
AB6: Macromonomer AB6, terminal methacryloyl group acrylic polymer
(Manufactured by Toagosei Co., Ltd.)
IBXA: Isobornyl acrylate (Light acrylate IB-XA, manufactured by Kyoeisha Chemical Co., Ltd.)
UN6200: Art resin UN-6200 (polyether-based bifunctional urethane acrylate,
(Negami Kogyo Co., Ltd.)
UMM1001: Actflow UMM1001 (solvent-free acrylic resin, hydroxyl value: 94)
UT1001: Actflow UT1001 (solvent-free acrylic resin, hydroxyl value: 58)
5018: Nipponporan 5018 (polyester polyol, hydroxyl value: 52-60,
(Made by Nippon Polyurethane Industry Co., Ltd.)
PEG600: Polyethylene glycol 600 (polyether diol, hydroxyl value: 570 to 630,
(Pure Chemical Co., Ltd.)
T5650J: Duranol T5650J (polycarbonate diol, hydroxyl value: 51-61,
(Asahi Kasei Corporation)
184: Irgacure 184 (photoinitiator, 1-hydroxycyclohexyl phenyl ketone,
BASF)

  The evaluation was according to the following method.

(1) Wetting and spreading of the coating solution after bonding:
After irradiating the coating solution with UV and leaving it at room temperature for a specified time, the members are bonded together, and the wet spread of the adhesive required for the bonding is visually evaluated.
○: Passed and smoothly spread throughout the entire component
Δ: Pass, time is required, but the entire member is wet and spread
Δ ×: rejected, wet spread, but insufficient
X: Fail, almost no wet spread (2) Light-shielding part curability;
After pasting together, leave at room temperature for a day. A force is applied from above the light-shielding part of the bonded member, and the presence or absence of adhesive flow is visually confirmed.
○: Pass, no adhesive flow
○ to △: Pass, adhesive slightly flows but no elution
△: Fail, adhesive flow
X: Fail, adhesive flows and elutes easily (3) Transmittance:
The light transmittance of the test piece was measured in the range of 400 to 800 nm with a spectrophotometer (U-3000, manufactured by Hitachi High-Technologies Corporation) (blank: 2 mm thick glass plate).
(4) Elongation:
A cured film of an adhesive composition having a thickness of 300 μm was prepared, and the stretched film was pulled with a tensile tester (Shimadzu EZ-S 500N) at a speed of 5 mm / min, and the elongation until cutting was measured.
(5) Storage elastic modulus:
A cured film of an adhesive composition having a thickness of 500 μm was prepared, and viscoelasticity was measured in a tensile mode at a frequency of 1 Hz (viscoelasticity measuring apparatus: DMS6100 manufactured by SII Nanotechnology).
(6) Curing shrinkage:
The liquid specific gravity and the solid specific gravity were measured using an electronic hydrometer (SD-200L manufactured by Alpha Mirage Co., Ltd.) and calculated by the following formula.
Curing shrinkage% = [(specific gravity after curing−specific gravity before curing) / specific gravity after curing] × 100
(7) Adhesive strength:
The two pieces of glass of the test piece are pulled up and down with a tester and the adhesive strength is measured.
(8) Moisture resistance:
The specimen is left for 500 hours in an environment of 80 ° C. and 90% RH, and the appearance is observed after removal.
(9) Boiling water resistance:
Immerse the test piece in boiling water for 3 hours and observe the appearance after removal. Evaluation is based on the following evaluation criteria.
○: No change, passed
Δ: Slightly whitened, passed
×: Whitening or failure
Xx: peeling, fail

The adhesive method of the present invention is an optical film, food film, industrial material film, glass because the adhesive composition has delayed curing, high transparency, and excellent moisture / water resistance and flexibility. Taking advantage of the excellent adhesion of various transparent members such as polycarbonate and PMMA, or the light-curing part curability, it can be used for various purposes such as bonding of transparent members with light-shielding parts and polarizing films. It is useful in.

Claims (7)

A method for bonding a member using an ultraviolet curable adhesive,
A (meth) acrylic resin (A) having a radical polymerizable group, which is produced from a (meth) acrylic monomer in one step and obtained by polymerization of the monomer and radical polymerizable double bond modification in the step. : 10 to 90% by mass,
Vinyl compound (B) having a radically polymerizable double bond: 10 to 90% by mass,
And photopolymerization initiator (C): 0.01 to 10% by mass,
Containing an adhesive composition (however, mass% is based on the entire adhesive composition),
An application step of applying a coating liquid comprising the adhesive composition to at least one member, a curing step of irradiating the coating liquid with ultraviolet rays to semi-cure the adhesive composition, and a semi-cured adhesive layer A bonding step of laminating other members. In the adhesive composition, the (meth) acrylic resin (A) having a radical polymerizable group is one or a mixture of two or more compounds selected from alkyl (meth) acrylates having 1 to 18 carbon atoms, or Produced from a mixture of these and a styrenic monomer, or one or a mixture of two or more compounds selected from alkyl (meth) acrylates having 1 to 18 carbon atoms, or a mixture of these and a styrenic monomer; The adhesion method according to claim 1, wherein the adhesion method is produced from (meth) acrylate or (meth) acrylic acid having a functional group selected from a glycidyl group, a hydroxyl group and a silyl group. The adhesion method according to claim 1 or 2, wherein the (meth) acrylic resin (A) having a radical polymerizable group in the adhesive composition is produced by high temperature polymerization or high temperature high pressure polymerization. The adhesion method according to any one of claims 1 to 3, wherein the adhesive composition further contains a non-radically polymerizable flexible component (D): 5 to 70 mass % . The adhesive composition is selected from (meth) acrylic resins, polyester diols, polyether diols, polycarbonate diols and modified products thereof in which the non-radical polymerizable flexible component (D) does not have a radical polymerizable group. The adhesion method according to claim 4 which is at least one sort. The adhesive composition has a cured product having an elongation (25 ° C) of 50% or more, a storage elastic modulus (25 ° C) of 1 × 10 ⁷ Pa or less, and a curing shrinkage of 5% or less. 6. The bonding method according to any one of 5 above. Furthermore, the adhesion method in any one of Claims 1-6 which provided the thermosetting process.

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