JP2019085488A - Method of bonding substrates - Google Patents

Abstract

To provide a method of bonding substrates which enables control of the thickness of an adhesion layer, and adjustment and correction of a sticking position.SOLUTION: A method of bonding a pair of a first substrate and a second substrate facing each other with an ultraviolet-curable liquid silicone rubber adhesive comprises the steps of: applying the adhesive to the first substrate; irradiating the adhesive with ultraviolet ray to semi-cure the adhesive; stacking the second substrate on the first substrate via the semi-cured adhesion layer to stick them together; and full-curing the adhesive by ultraviolet irradiation.SELECTED DRAWING: None

Description

  The present invention relates to a method of bonding a substrate, and more particularly to a method of bonding a multilayer substrate using a UV curable liquid silicone rubber adhesive.

  Adhesive used when bonding another substrate such as touch panel, cover glass, cover film or FPD to a substrate such as liquid crystal module (LCM) or flexible printed circuit board (FPC) as an image display device Acrylic resins, epoxy resins, and silicone adhesives are used as the resin. By bonding with such a curing type adhesive, a gap is eliminated, display recognition and durability are improved, and reflection of sunlight and the like is suppressed. Currently, acrylic and epoxy resins are used for these bonding materials, but in recent years, they are particularly optically transparent, excellent in light resistance and heat resistance, and have a low elastic modulus. Attention has been focused on silicone rubber adhesives (Patent Documents 1 and 2).

  As the image display device shifts from a small size to a large size display device, silicone rubber adhesives with lower elastic modulus have been studied as adhesives to bond materials having different thermal expansion coefficients, and further, Also in the configuration of the image display apparatus, a corresponding structure has been studied in which an adhesive, which is also a bonding material, is thickened so that thermal changes of different substrates can be followed. However, to use a thermosetting or UV curable silicone rubber adhesive and obtain an adhesive layer of a predetermined thickness, an adhesive called a dam agent is applied to the outer periphery of the area to which the first substrate is to be adhered. After coating and filling the adhesive on the inner side, the second substrate is bonded, heated and irradiated with ultraviolet rays to cure and bond. However, in this process, the dam agent is indispensable, and furthermore, since it is liquid before heating and before irradiation with ultraviolet light, adjustment of the bonding position is difficult, and after the second substrate is bonded, In order to adhere firmly, there existed a problem that repair was not possible.

JP, 2014-005354, A JP, 2014-169412, A

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method of bonding a substrate capable of controlling the thickness of a bonding layer and capable of adjusting and repairing a bonding position.

  In order to achieve the above object, in the present invention, a method of bonding a pair of opposing first substrates to a second substrate using a UV curable liquid silicone rubber adhesive, wherein the adhesive is placed on the first substrate Applying ultraviolet rays to the adhesive, irradiating the adhesive with UV light, bonding the second substrate through the adhesive layer after the semi-curing, and irradiating UV light. And a step of main curing the adhesive.

  With such a method, the thickness of the adhesive layer can be controlled, and adjustment or repair of the bonding position becomes possible.

（式中、ｍは０、１又は２の整数、Ｒ^１は水素原子、フェニル基又はハロゲン化フェニル基、Ｒ^２は水素原子又はメチル基、Ｒ^３は１価の同一又は異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基、Ｚ^１は−Ｒ^４−、−Ｒ^４Ｏ−、又は、−Ｒ^４（ＣＨ_３）_２ＳｉＯ−（ここで、Ｒ^４は２価の同一又は異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基）で表される２価の基、Ｚ^２は酸素原子、又は、２価の同一若しくは異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基である。）
で表される構造を分子中に少なくとも２つ有するオルガノポリシロキサンであって、オルガノポリシロキサン単位が全シロキサン単位に対してＳｉＯ_４／２、およびＳｉＯ_３／２単位を有せず、ＳｉＯ_２／２、ＳｉＯ_１／２単位のみで構成された直鎖状であるオルガノポリシロキサン１００質量部に対して、
（Ｂ）光重合開始剤：０．０１〜１０質量部、
を含有してなる紫外線硬化型液状オルガノポリシロキサン組成物を用いることが好ましい。 Further, as the ultraviolet curable liquid silicone rubber adhesive,
(A) General Formula (1):

(Wherein, m is an integer of 0, 1 or 2, R ¹ is a hydrogen atom, a phenyl group or a halogenated phenyl group, R ² is a hydrogen atom or a methyl group, R ³ is a monovalent identical or different carbon a substituted or unsubstituted hydrocarbon group having the number of atoms of 1 to 10, ^{Z 1} is ^{-R 4 -, - R 4 O-} , _{^{or, -R 4 (CH 3) 2}} SiO- ( wherein, ^{R 4} is a divalent Or a divalent group represented by the same or different substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms), Z ² is an oxygen atom, or a carbon which may be the same or different, divalent It is a substituted or unsubstituted hydrocarbon group having 1 to 10 atoms.)
The structure represented by the a least two with organopolysiloxane in the molecule, _{SiO 4/2,} and does not have a _{SiO 3/2} unit of the organopolysiloxane units are all siloxane units, SiO _{2 / And} 100 parts by mass of a linear organopolysiloxane composed only of SiO _1/2 units,
(B) Photopolymerization initiator: 0.01 to 10 parts by mass,
It is preferable to use an ultraviolet-curable liquid organopolysiloxane composition comprising

  Such a composition can be suitably used as an ultraviolet curable liquid silicone rubber adhesive.

（式中、ｍ’は０、１又は２の整数、Ｒ^１’は水素原子、フェニル基又はハロゲン化フェニル基、Ｒ^２’は水素原子又はメチル基、Ｒ^３’は１価の同一又は異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基、Ｚ^１’は−Ｒ^４’−、−Ｒ^４’Ｏ−、又は、−Ｒ^４’（ＣＨ_３）_２ＳｉＯ−（ここで、Ｒ^４’は２価の同一又は異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基）で表される２価の基、Ｚ^２’は酸素原子、又は、２価の同一若しくは異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基である。）
で表される構造を分子中に少なくとも１つ有するオルガノポリシロキサンであって、全シロキサン単位に対してＳｉＯ_４／２、および／またはＳｉＯ_３／２単位を平均で１〜５０ｍｏｌ％有する分岐状であるオルガノポリシロキサンを、前記（Ａ）成分１００質量部に対して、１〜１００質量部さらに含有してなる紫外線硬化型液状オルガノポリシロキサン組成物を用いることが好ましい As said ultraviolet curable liquid silicone rubber adhesive,
(C) General formula (2):

(Wherein, m ′ is an integer of 0, 1 or 2; R ^{1 ′} is a hydrogen atom, a phenyl group or a halogenated phenyl group, R ^{2 ′} is a hydrogen atom or a methyl group, R ^{3 ′} is a monovalent identical or different And the substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms, Z ^{1 ′} may be —R ^{4 ′} —, —R ^{4 ′} O—, or —R ^{4 ′} (CH ₃ ) ₂ SiO— ( Here, R ^{4 ′} is a divalent group represented by the same or different divalent C 1-10 substituted or unsubstituted hydrocarbon group, and Z ^{2 ′} is an oxygen atom or It is a substituted or unsubstituted C1-C10 substituted or unsubstituted hydrocarbon group which may be the same or different.
Organopolysiloxane having in its molecule at least one structure represented by and branched with an average of 1 to 50 mol% of SiO _4/2 and / or SiO _3/2 units with respect to all siloxane units. It is preferable to use a UV curable liquid organopolysiloxane composition further comprising 1 to 100 parts by mass of a certain organopolysiloxane with respect to 100 parts by mass of the component (A).

  With an adhesive containing such component (C), the mechanical strength after curing is good.

  As described above, the ultraviolet curable liquid silicone rubber adhesive used in the present invention can be adhered to the adherend by an appropriate amount of light irradiation without using a primer, a solvent or heat. At this time, since the adhesive used in the present invention is easy to control the semi-hardening, the thickness control of the adhesive layer, which is a problem, is also performed by irradiating the ultraviolet light immediately after applying the adhesive to the first substrate. This is possible by securing an adhesive layer of a certain thickness, and since it is in a semi-cured state having adhesiveness at this time, adjustment and repair of the bonding position, which is a problem, becomes possible. Furthermore, the UV curable silicone rubber adhesive used in the present invention can be completely bonded by bonding the second substrate in a semi-cured state with a tacky feeling and irradiating again with UV light. is there.

It is the schematic of the plane tensile adhesive strength test in the Example of this invention.

  As described above, there has been a demand for development of a method of bonding a substrate that can control the thickness of the bonding layer and can adjust and repair the bonding position.

  As a result of intensive investigations on the above problems, the present inventors can control the thickness of the adhesive layer by bonding the substrates in a semi-cured state in which the adhesive layer has a tacky feeling, and bonding is possible. The inventors found that the position can be adjusted and repaired, and completed the present invention.

  That is, the present invention relates to a method of bonding a pair of opposing first substrates to a second substrate using an ultraviolet-curable liquid silicone rubber adhesive, wherein the adhesive is coated on the first substrate and an adhesive layer is formed. The step of forming, the step of irradiating the adhesive layer with ultraviolet rays to cause the adhesive layer to be semi-cured, the laminating step of laminating the second substrate through the adhesive layer after being semi-cured, and the step of irradiating the ultraviolet rays further And curing the adhesive layer.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

Bonding method
The present invention comprises the steps of applying an ultraviolet-curable liquid silicone rubber adhesive onto a first substrate to form an adhesive layer, irradiating the adhesive layer with ultraviolet light to semi-cure the adhesive layer, and after semi-curing And a step of laminating the second substrate through the adhesive layer, and a step of further curing the adhesive layer by irradiation with ultraviolet light.

  The present invention is a flat panel display such as a liquid crystal display (LCD), an organic EL display (OLED), a plasma display (PDP), a flexible display (FPD), or a touch panel FPD, 3D display, electronic book, etc. UV curable liquid silicone used when bonding another substrate such as a touch panel, cover glass, cover film or FPD to a substrate such as a liquid crystal module (LCM) or flexible printed wiring board (FPC) It is suitable as a bonding method of a multilayer substrate using a rubber adhesive.

  Further, the bonding method of the present invention can be suitably used in the manufacture of an image display device, and in particular, a bonding method of an ultraviolet curable liquid silicone rubber adhesive interposed between a liquid crystal module and a cover glass or a cover film. As preferred.

[Step of applying adhesive and forming adhesive layer]
In the bonding method of the present invention, a UV curable liquid silicone rubber adhesive described later is applied on the first substrate to form a bonding layer.

  In this step, the adhesive is uniformly applied on the first substrate, and the application method is preferably 10 to 3000 microns by spray coating, flow coating, curtain coating, screen coating, casting and combinations thereof. The adhesive is applied to a thickness of more preferably 50 to 1000 microns, particularly preferably 100 to 800 microns to form an adhesive layer. If the thickness is 10 microns or more, the irregularities on the substrate surface can be absorbed more reliably, and if the thickness is 3000 microns or less, the cost of the UV curable silicone rubber adhesive can be kept low. Yes, it is economical.

  As a 1st board | substrate, a liquid crystal module, a flexible printed wiring board, a touch panel, a cover glass, a cover film, a flat panel display etc. are mentioned.

(UV-curable liquid silicone rubber adhesive)
In the bonding method of the present invention, a UV curable liquid silicone rubber adhesive is used. The ultraviolet-curable liquid silicone rubber adhesive used in the present invention is excellent in coating property without solvent, easy to control semi-hardening after irradiation with ultraviolet light, and excellent in adhesive strength after main curing.

  It is preferable to use the ultraviolet curable polysiloxane composition containing the component mentioned later as an ultraviolet curable liquid silicone rubber adhesive used by this invention. In addition, in the following description, the weight average molecular weight of polystyrene conversion is measured by gel permeation chromatography.

（式中、ｍは０、１又は２の整数、Ｒ^１は水素原子、フェニル基又はハロゲン化フェニル基、Ｒ^２は水素原子又はメチル基、Ｒ^３は１価の同一又は異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基、Ｚ^１は−Ｒ^４−、−Ｒ^４Ｏ−、又は、−Ｒ^４（ＣＨ_３）_２ＳｉＯ−（ここで、Ｒ^４は２価の同一又は異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基）で表される２価の基、Ｚ^２は酸素原子、又は、２価の同一若しくは異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基である。）
で表される構造を分子中に少なくとも２つ有するオルガノポリシロキサンであって、オルガノポリシロキサン単位が全シロキサン単位に対してＳｉＯ_４／２、およびＳｉＯ_３／２単位を有せず、ＳｉＯ_２／２、ＳｉＯ_１／２単位のみで構成された直鎖状であるオルガノポリシロキサンを使用することができる。 -(A) component-
As the component (A), general formula (1):

(Wherein, m is an integer of 0, 1 or 2, R ¹ is a hydrogen atom, a phenyl group or a halogenated phenyl group, R ² is a hydrogen atom or a methyl group, R ³ is a monovalent identical or different carbon a substituted or unsubstituted hydrocarbon group having the number of atoms of 1 to 10, ^{Z 1} is ^{-R 4 -, - R 4 O-} , _{^{or, -R 4 (CH 3) 2}} SiO- ( wherein, ^{R 4} is a divalent Or a divalent group represented by the same or different substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms), Z ² is an oxygen atom, or a carbon which may be the same or different, divalent It is a substituted or unsubstituted hydrocarbon group having 1 to 10 atoms.)
The structure represented by the a least two with organopolysiloxane in the molecule, _{SiO 4/2,} and does not have a _{SiO 3/2} unit of the organopolysiloxane units are all siloxane units, SiO _{2 /} A linear organopolysiloxane composed of only ₂ or SiO1 _{/ 2} units can be used.

In the general formula (1), the monovalent identical or different substituted or non-substituted hydrocarbon group having 1 to 10 carbon atoms represented by R ³ generally has 1 to 10 carbon atoms, preferably Specifically, methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tert-butyl groups, pentyl groups, neopentyl groups, hexyl groups, cyclohexyl groups, octyl groups. Alkyl groups such as nonyl group and decyl group; aryl groups such as phenyl group, tolyl group, xylyl group and naphthyl group; aralkyl groups such as benzyl group, phenylethyl group and phenylpropyl group; vinyl group, allyl group, propenyl And hydrocarbon groups such as alkenyl groups such as isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group and octenyl group; A substituted hydrocarbon group in which a part or all of hydrogen atoms of a hydrocarbon group is substituted with a halogen atom such as fluorine, bromine or chlorine, or a cyano group, such as chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group Halogen-substituted alkyl groups, cyanoethyl groups and the like, and further, those substituted or unsubstituted hydrocarbon groups which include an ether bond (etheric oxygen atom), an amide bond or the like as part of a hydrocarbon chain are also included. Ru.

Examples of the substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms represented by R ⁴ or Z ² include alkylene groups such as methylene, ethylene and trimethylene, and the like. Some or all of the hydrogen atoms of the hydrocarbon group of the above may be substituted with a halogen atom such as fluorine, bromine or chlorine, a cyano group or the like, and further an ether bond, an amide bond or the like in these hydrocarbon chains Included is also included.

In the general formula (1), when Z ¹ is a divalent group represented by —R ⁴ —, Z ² is preferably an oxygen atom, and Z ¹ is —R ⁴ O— or — When it is a divalent group represented by R ⁴ (CH ₃ ) ₂ SiO—, Z ² is a divalent identical or different substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms Is preferred.

（式中、ｍ、Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４は一般式（１）に関して上記定義の通りである。）
で表される構造として存在する。この一般式（３）の具体例としては、下記のもの等が挙げられる In a preferred embodiment, the structure represented by the above general formula (1) is a compound represented by the following general formula (3):

(Wherein, m, R ¹ , R ² , R ³ and R ⁴ are as defined above in relation to the general formula (1))
Exists as a structure represented by The following may be mentioned as specific examples of the general formula (3)

  The organopolysiloxane of component (A) is exemplified below. These organopolysiloxanes can be used alone or in combination of two or more as the component (A).

（式中、括弧が付された各シロキサン単位の配列はランダムであってもブロックであってもよい。）

(In the formula, the arrangement of each siloxane unit attached with parentheses may be random or block.)

  As a viscosity of (A) component, what has a viscosity of 100-200,000 mPa * s in 25 degreeC is suitable, a preferable range is 500-50,000 mPa * s, and a more preferable range is 1,000-5. It is 1,000 mPa · s. When the viscosity of the component (A) is greater than 100 mPa · s, the cured product obtained by irradiating the adhesive used in the present invention with ultraviolet light is not too hard and can be suitably used for an image display device (A When the viscosity of the component) is less than 200,000 mPa · s, the workability is not inferior.

-(B) component-
As a photoinitiator of (B) component, what is well-known as what is used for photocuring of an acryl-type functional group can be used all. For example, benzoins and substituted benzoins (eg, alkyl ester substituted benzoins), Michler's ketone, dialkoxyacetophenones such as 2,2-diethoxyacetophenone ("DEAP"), benzophenones and substituted benzophenones, acetophenones and substituted Acetophenone, xanthone and substituted xanthone, 2,2-acyl phosphine oxide and the like. Specific examples of desirable photopolymerization initiators include diethoxyacetophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, diethoxyxanthone, chloro-thio-xanthone, azobisisobutyronitrile, N-methyldiethanolamine benzophenone, There is bis (2,4,6-trimethylbenzoyl) phenyl phosphine oxide and mixtures thereof. Visible light initiators can also be used, examples of which are camphoroquinone peroxy ester initiators and non-fluorene-carboxylic acid peroxy esters. A particularly desirable photoinitiator for the present invention is DEAP.

Photopolymerization initiators are also commercially available, for example, from Ciba Specialty Chemicals, Inc. under the trade names IRGACURE and DAROCURE. Specifically, for example, IRGACURE 184 (1-hydroxycyclohexyl phenyl ketone), IRGACURE 907 (2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one), IRGACURE 369 (2 -Benzyl-2-N, N-dimethylamino-1- (4-morpholinophenyl) -1-butanone), IRGACURE 500 (combination of 1-hydroxycyclohexyl phenyl ketone and benzophenone), IRGACURE 651 (2,2-dimethoxy) -2-phenylacetophenone), IRGACURE 1700 (bis (2,6-dimethoxybenzoyl-2,4,4-trimethylphenyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one Combinations), IRGACURE 819 [Bis (2,4,6-trimethylbenzoyl) phenyl phosphine oxide], DAROCURE 1173 (2-hydroxy-2-methyl-1-phenyl-1-propane), and 4265 (2,4,6-) Combinations of trimethylbenzoyldiphenyl-phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one), and as visible light (blue) photoinitiators, dl-camphorquinone and IRGACURE 784 There is bis (η ⁵ -2,4-cyclopentadien-1-yl) -bis [2,6-difluoro-3- (1H-pyrrol-1-yl) phenyl] titanium).

  The blending amount of the photopolymerization initiator which is the component (B) is usually 0.01 to 10 parts by mass with respect to 100 parts by mass of the component (A), and the reactivity and the deep curing desired in the present invention From the aspect of the composition, the amount is particularly preferably 0.1 to 5 parts by mass.

  The component (B) can be used singly or in combination of two or more. The photoinitiator may also be a polymer in which the initiators are reacted and bound. Such photoinitiators are described in US Pat. Nos. 4,477,326 and 4,587,276.

  Other free radical initiators such as peroxide initiators can also be used in combination with component (B). As for the compounding quantity in that case, 0.1-5 mass parts is preferable with respect to 100 mass parts of (A) component. The adhesive agent used in the present invention is cured by heating at a temperature of about 60 to 100 ° C. if necessary, for the location of the adhesive used in the present invention which can not be irradiated directly with ultraviolet light by adding peroxide in combination. It can also be done.

（式中、ｍ’は０、１又は２の整数、Ｒ^１’は水素原子、フェニル基又はハロゲン化フェニル基、Ｒ^２’は水素原子又はメチル基、Ｒ^３’は１価の同一又は異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基、Ｚ^１’は−Ｒ^４’−、−Ｒ^４’Ｏ−、又は、−Ｒ^４’（ＣＨ_３）_２ＳｉＯ−（ここで、Ｒ^４’は２価の同一又は異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基）で表される２価の基、Ｚ^２’は酸素原子、又は、２価の同一若しくは異なってもよい炭素原子数１〜１０の置換又は非置換の炭化水素基である。）
で表される構造を分子中に少なくとも１つ有するオルガノポリシロキサンであって、全シロキサン単位に対してＳｉＯ_４／２、および／またはＳｉＯ_３／２単位を平均で１〜５０ｍｏｌ％有する分岐状であるオルガノポリシロキサンである。 -(C) component-
The organopolysiloxane of component (C) has the general formula (2):

(Wherein, m ′ is an integer of 0, 1 or 2; R ^{1 ′} is a hydrogen atom, a phenyl group or a halogenated phenyl group, R ^{2 ′} is a hydrogen atom or a methyl group, R ^{3 ′} is a monovalent identical or different And the substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms, Z ^{1 ′} may be —R ^{4 ′} —, —R ^{4 ′} O—, or —R ^{4 ′} (CH ₃ ) ₂ SiO— ( Here, R ^{4 ′} is a divalent group represented by the same or different divalent C 1-10 substituted or unsubstituted hydrocarbon group, and Z ^{2 ′} is an oxygen atom or It is a substituted or unsubstituted C1-C10 substituted or unsubstituted hydrocarbon group which may be the same or different.
Organopolysiloxane having in its molecule at least one structure represented by and branched with an average of 1 to 50 mol% of SiO _4/2 and / or SiO _3/2 units with respect to all siloxane units. It is an organopolysiloxane.

  The component (C) is preferably in the range of 1 to 100 parts by mass with respect to 100 parts by mass of the component (A) on the premise that the component (C) is used. If the component (C) is 1 part by mass or more, the desired mechanical strength of the obtained cured product can be improved, and if the component (C) is 100 parts by mass or less, the hardness of the resulting cured product is not too hard. It is suitable as an adhesive used in the invention.

  The organopolysiloxane of component (C) is exemplified below. These organopolysiloxanes may be used alone or in combination of two or more as the component (C).

(C-1)
The following MA units (SiO _1/2 ), M units (SiO _1/2 ) and Q units (SiO _4/2 ) are _prepared, and the molar ratio of these units is MA: M: Q = 1: 4: 5. Organopolysiloxane having a weight average molecular weight of 5,000 in terms of polystyrene.

・ MA unit:

・ M unit:

・ Q unit:

(C-2)
It consists of the following MA-D unit (SiO2 _{/ 2} ), D unit (SiO2 _{/ 2} ), and T unit (SiO3 _{/ 2} ), and a molar ratio is MA-D: D: T = 2: 6: 7. An organopolysiloxane having a polystyrene-equivalent weight average molecular weight of 3,500.

・ MA-D unit:

・ D unit:

・ T unit:

  As the viscosity of the component (C), as the component (A), one having a viscosity of 100 to 200,000 mPa · s at 25 ° C. is preferable, and a preferable range is 500 to 50,000 mPa · s, The preferred range is 1,000 to 10,000 mPa · s. When the viscosity of the component (C) is greater than 100 mPa · s, the cured product obtained by irradiating the adhesive used in the present invention with ultraviolet light is not too hard and can be suitably used for an image display device (C When the viscosity of the component) is less than 200,000 mPa · s, the workability is not inferior.

-Other ingredients-
Other components can be blended into the adhesive used in the present invention as required.

Reactive diluent:
Reactive diluent that does not contain silicone for the purpose of giving durability to high temperature, such as transparency after moisture and heat resistance, adhesion to substrate, etc., such as viscosity adjustment of adhesive agent and hardness of hardened material, etc. It can be added.

Silicone-free reactive diluents include (meth) acrylates as shown by H ₂ C = CGCO ₂ Q, wherein G is hydrogen, halogen, or having from 1 to about 4 carbon atoms. Alkyls, Q is selected from alkyls having 1 to about 16 carbon atoms, cycloalkyls, alkenyls, cycloalkenyls, alkaryls, aralkyls or aryls, any of which may optionally be silanes, It may be substituted or capped with silicon, oxygen, halogen, carbonyl, hydroxyl, ester, carboxylic acid, urea, urethane, carbamate, amine, amide, sulfur, sulfonate, sulfone and the like.

  More specific examples of (meth) acrylates that are particularly desirable as reactive diluents include polyethylene glycol di (meth) acrylate, ethoxylated bisphenol-A (meth) acrylate ("EBIPA" or "EBIPMA") Bisphenol-A di (meth) acrylate, tetrahydrofuran (meth) acrylate and di (meth) acrylate, citronellyl acrylate and citronellyl methacrylate, hydroxypropyl (meth) acrylate, hexanediol di (meth) acrylate ("HDDA" or "HDDMA" "", Trimethylolpropane tri (meth) acrylate, tetrahydrodicyclopentadienyl (meth) acrylate, ethoxylated trimethylolpropane triacrylate ("E TA "), triethylene glycol diacrylate and triethylene glycol dimethacrylate (" TRIEGMA "), dioxane glycol di (meth) acrylate (for example, KAYARAD R-604, dioxane glycol diacrylate manufactured by Nippon Kayaku Co., Ltd.), tri There are cyclodecane dimethylol di (meth) acrylate (for example, KAYARAD R-684, tricyclodecane dimethylol diacrylate and the like manufactured by Nippon Kayaku Co., Ltd.), and isobornyl acrylate and isobornyl methacrylate. Of course, these (meth) acrylates can be used alone or in combination of two or more as a reactive diluent.

  When using a reactive diluent, it may be blended in an amount of 0.05 to 50 parts by mass with respect to 100 parts by mass of the component (A).

Modifier:
The adhesive used in the present invention is desired in specific applications that require high temperature durability, particularly transparency after moist heat resistance, and adhesion to various substrates such as glass, acrylic, polycarbonate and PET. Other components that modify such cured or uncured properties may also be included. For example, an adhesion promoter such as (meth) acryloxypropyltrimethoxysilane, trialkyl- or triallyl-isocyanurate, glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, etc. is contained in an amount of 5% by mass or less obtain.

  Also, non- (meth) acrylic silicone diluents or plasticizers can be added in amounts up to about 30% by weight. Non- (meth) acrylic silicones are trimethylsilyl-terminated oils having a viscosity of 100 to 10,000 mPa · s at 25 ° C., and silicone rubbers. Non- (meth) acrylic silicones may also contain copolymerizable groups such as vinyl groups for the purpose of being incorporated into the crosslinking of the adhesive used in the present invention.

・ Inorganic filler:
An inorganic filler may be added to this adhesive. That is, silicas such as fumed silica may be used, which may be untreated (hydrophilic) or treated to be hydrophobic. Any fumed silica may be used alone or in combination of two or more.

  When using an inorganic filler, it may mix | blend 0.1-20 mass parts with respect to 100 mass parts of (A) component.

  The method of preparing the adhesive used in the present invention is preferably in the absence of ultraviolet light. Specifically, a UV-curable liquid silicone rubber adhesive can be obtained by using a mixing stirrer equipped with a vacuum degassing apparatus and mixing the above-mentioned components followed by degassing.

[Step of semi-curing the adhesive layer by irradiating ultraviolet light]
In the bonding method of the present invention, a UV curable liquid silicone rubber adhesive is applied on the first substrate to form a bonding layer, and then the UV light is irradiated to semi-cure the bonding layer.

  A useful source of UV light to semi-cure the adhesive layer is a conventional mercury vapor lamp or metal halide lamp designed to emit UV energy in various UV wavelength bands, for example a specific single wavelength of only 365 nm. The LED lamp etc. which emit are mentioned.

  For example, a useful ultraviolet wavelength range for semi-curing the adhesive layer is desirably 220-450 nm. Further, in order to semi-cure, it is sufficient to adjust the integrated light amount by the irradiation time.

[Laminating process for laminating the second substrate through the adhesive layer]
In the bonding method of the present invention, the second substrate is laminated and bonded to the first substrate through the semi-cured adhesive layer.

  As a bonding method, by using a vacuum bonding apparatus and performing bonding under a vacuum, mixing of air bubbles can be prevented and a uniform adhesive layer can be obtained. In addition, a vacuum bonding apparatus is an apparatus which bonds non-air bubbles in a vacuum atmosphere, and can generally use a panel assembly apparatus used by a smart phone, a tablet PC, a touch panel or the like. The ultimate vacuum of the vacuum bonding apparatus is 1000 Pas or less, preferably 100 Pas or less, preferably 20 Pas or less.

  Moreover, as a 2nd board | substrate used by this invention, the thing similar to what was illustrated as a 1st board | substrate can be used.

[Step to fully cure the adhesive layer]
In the bonding method of the present invention, the laminate of the first substrate and the second substrate bonded in the above is further irradiated with ultraviolet light to substantially cure the semi-cured adhesive layer.

  Useful sources of UV light for full curing of the semi-cured adhesive layer include those similar to those used to semi-cure the adhesive layer. Also in this case, in order to make the main curing, the integrated light amount with the semi-curing may be adjusted by the irradiation time.

  EXAMPLES The present invention will be specifically described below using Examples and Comparative Examples, but the present invention is not limited to these. In addition, the weight average molecular weight of polystyrene conversion is measured by gel permeation chromatography, and the viscosity is a value measured using a rotational viscometer at 25 ° C.

The ultraviolet irradiation conditions in the following examples and comparative examples were as follows.
Ultraviolet Irradiation Conditions The accumulated light quantity was adjusted with an ultraviolet irradiation intensity of 100 mW / cm ² (365 nm) on the surface of the material and an irradiation time using an eye UV electronic controller manufactured by Iwasaki Electric Co., Ltd.

Determination of Cured State Tack-Free Test According to JIS K 6249 According to the finger touch method, when the surface of the adhesive layer after ultraviolet irradiation is touched with a finger, the state in which the adhesive layer adheres to the finger is regarded as semi-cured. Furthermore, the presence or absence of the fluidity of the adhesive layer was determined.
Uncured: sticky and fluid.
Semi-cured: sticky but not flowable.
Curing: not sticky or fluid.

Flat Tensile Adhesion Strength Test As shown in FIG. 1, using glass plates 1 and 2 (first and second substrates) 25 mm × 100 m and 2 mm thick, the glass plate 1 (first An ultraviolet-curable liquid silicone rubber adhesive having an area equal to or larger than the adhesion area was coated on the substrate to a thickness of about 500 μm to form an adhesive layer 3 and irradiated with ultraviolet light for a predetermined time. Furthermore, another glass plate 2 (second substrate) was placed on the surface of the adhesive layer 3 after irradiation, and main curing was performed. As a method of measuring the adhesive strength, the strength was measured in which the glass plate bonded in a cross shape was peeled up and down so as to be perpendicular to the bonding surface.

(Examples 1 and 2 and Comparative Examples 1 and 2)
100 g of organopolysiloxane having a viscosity of 3,000 mPa · s at 25 ° C., 2 g of 2,2-diethoxyacetophenone (“DEAP”), and the following MA unit (SiO _{1) / 2)} and become from the M units _{(SiO 1/2)} and Q units _{(SiO 4/2),} the molar ratio of units MA: M: Q = 1: 4: a 5, the weight in terms of polystyrene An ultraviolet curable liquid silicone rubber adhesive (Sample A) was prepared by uniformly mixing 10 g of an organopolysiloxane having an average molecular weight of 5,000 and 1 g of 3-methacryloxypropyltrimethoxysilane.

（式中、括弧が付された各シロキサン単位の配列はランダムであってもブロックであってもよい。）

(In the formula, the arrangement of each siloxane unit attached with parentheses may be random or block.)

・ MA unit:

・ M unit:

・ Q unit:

The sample A was applied to a glass plate 1 with a thickness of about 500 μm to form an adhesive layer 3 and irradiated with ultraviolet light of a predetermined integrated light amount. Next, another glass plate 2 was bonded onto the adhesive layer 3 and irradiated with ultraviolet light having a cumulative light quantity of 24,000 mJ / cm ² . The planar tensile adhesive strength was measured. The results are shown in Table 1.

From the results of Table 1, in Example 1 and Example 2, the planar tensile adhesive strength was good. In addition, since the adhesive layer is semi-cured when bonding the substrates, adjustment and repair of the bonding position is possible, and the thickness of the adhesive layer can be controlled. On the other hand, in Comparative Example 1 in which the substrates are bonded to each other in a state where the adhesive layer is not cured, although the planar tensile strength is good, the thickness of the adhesive layer largely changes due to the bonding, and the thickness of the adhesive layer is controlled. It was not possible to adjust the bonding position. Furthermore, in the comparative example 2 which bonded substrates in the state which hardened | cured the contact bonding layer, ie, the state without adhesive feeling, board | substrates peeled.
From the above, it was confirmed that, with the bonding method of the present invention, the thickness of the bonding layer can be controlled and the bonding position can be adjusted.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has the substantially same constitution as the technical idea described in the claims of the present invention, and the same effects can be exhibited by any invention. It is included in the technical scope of

  1 ... glass plate (first substrate), 2 ... glass plate (second substrate) 3 ... adhesive layer.

Claims (3)

  A method of adhering a pair of opposing first and second substrates using an ultraviolet-curable liquid silicone rubber adhesive, wherein the adhesive is applied on the first substrate to form an adhesive layer; The step of irradiating the adhesive layer with ultraviolet light to semi-cure the adhesive layer, the bonding step of laminating the second substrate through the adhesive layer after the semi-hardening, and further irradiating the ultraviolet light to form the adhesive layer And a curing step. As said ultraviolet curable liquid silicone rubber adhesive,
(A) General Formula (1):

(Wherein, m is an integer of 0, 1 or 2, R ¹ is a hydrogen atom, a phenyl group or a halogenated phenyl group, R ² is a hydrogen atom or a methyl group, R ³ is a monovalent identical or different carbon a substituted or unsubstituted hydrocarbon group having the number of atoms of 1 to 10, ^{Z 1} is ^{-R 4 -, - R 4 O-} , _{^{or, -R 4 (CH 3) 2}} SiO- ( wherein, ^{R 4} is a divalent Or a divalent group represented by the same or different substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms), Z ² is an oxygen atom, or a carbon which may be the same or different, divalent It is a substituted or unsubstituted hydrocarbon group having 1 to 10 atoms.)
The structure represented by the a least two with organopolysiloxane in the molecule, _{SiO 4/2,} and does not have a _{SiO 3/2} unit of the organopolysiloxane units are all siloxane units, SiO _{2 / And} 100 parts by mass of a linear organopolysiloxane composed only of SiO _1/2 units,
(B) Photopolymerization initiator: 0.01 to 10 parts by mass,
2. The bonding method according to claim 1, wherein the UV curable liquid organopolysiloxane composition comprising As said ultraviolet curable liquid silicone rubber adhesive,
(C) General formula (2):

(Wherein, m ′ is an integer of 0, 1 or 2; R ^{1 ′} is a hydrogen atom, a phenyl group or a halogenated phenyl group, R ^{2 ′} is a hydrogen atom or a methyl group, R ^{3 ′} is a monovalent identical or different And the substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms, Z ^{1 ′} may be —R ^{4 ′} —, —R ^{4 ′} O—, or —R ^{4 ′} (CH ₃ ) ₂ SiO— ( Here, R ^{4 ′} is a divalent group represented by the same or different divalent C 1-10 substituted or unsubstituted hydrocarbon group, and Z ^{2 ′} is an oxygen atom or It is a substituted or unsubstituted C1-C10 substituted or unsubstituted hydrocarbon group which may be the same or different.
Organopolysiloxane having in its molecule at least one structure represented by and branched with an average of 1 to 50 mol% of SiO _4/2 and / or SiO _3/2 units with respect to all siloxane units. The ultraviolet curable liquid organopolysiloxane composition further comprising 1 to 100 parts by mass of a certain organopolysiloxane with respect to 100 parts by mass of the component (A) is used. Bonding method.

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