Moisture and Radiation Curable Adhesive Composition and the Use Thereof

Abstract

The present invention discloses a moisture and radiation curable adhesive composition and the use thereof, in particular, to a moisture and radiation curable adhesive composition used as a liquid optical clear adhesive (LOCA) for handheld device and display (HHDD).

Claims

1. A moisture and radiation curable adhesive composition, comprising: (a) at least one mono(meth)acryloxy terminated polyorganosiloxane represented by the formula: ##STR00009## wherein, R.sub.1 to R.sub.9 are each independently selected from the group consisting of C.sub.1-C.sub.20 alkyl, C.sub.1-C.sub.20 alkoxyl, C.sub.2-C.sub.20 alkenyl, C.sub.3-C.sub.20 cycloalkyl, and C.sub.7-C.sub.22 aralkyl, with the proviso that at least one of R.sub.1 to R.sub.9 is C.sub.1-C.sub.20 alkoxyl, m is an integer of from 1 to 1000, A.sub.1 is represented by the formula (2):
(R.sub.10).sub.a(R.sub.11).sub.b(R.sub.12).sub.cR.sub.13   (2) wherein: R.sub.10 is C.sub.1-C.sub.20 alkylene, R.sub.11 is C.sub.6-C.sub.21 arylene, R.sub.12 is C.sub.1-C.sub.20 alkylene, R.sub.13 is (meth)acryloxy, a is an integer of from 0 to 10, b is an integer of from 0 to 10, and c is an integer of from 0 to 10; (b) at least one di(meth)acryloxy terminated polyorganosiloxane represented by the formula: ##STR00010## wherein: R.sub.14 to R.sub.21 are each independently selected from the group consisting of C.sub.1-C.sub.20 alkyl, C.sub.1-C.sub.20 alkoxyl, C.sub.2-C.sub.20 alkenyl, C.sub.3-C.sub.20 cycloalkyl, and C.sub.7-C.sub.22 aralkyl, with the proviso that at least one of R.sub.1 to R.sub.9 is C.sub.1-C.sub.20 alkoxyl, n is an integer of from 1 to 1000, A.sub.2 and A.sub.3 are each independently represented by the formula:
(R.sub.22).sub.d(R.sub.23).sub.e(R.sub.24).sub.fR.sub.25   (4) wherein: R.sub.22 is C.sub.1-C.sub.20 alkylene, R.sub.23 is C.sub.6-C.sub.21 arylene, R.sub.24 is C.sub.1-C.sub.20 alkylene, R.sub.25 is (meth)acryloxy, d is an integer of from 0 to 10, e is an integer of from 0 to 10, and f is an integer of from 0 to 10; (c) a photoinitiator; (d) a moisture curing catalyst; (e) optionally, a chain extender; and (f) optionally, a moisture crosslinker.

2. The moisture and radiation curable adhesive composition according to claim 1, wherein R.sub.1 to R.sub.9 are each independently selected from the group consisting of C.sub.1-C.sub.8 alkyl, C.sub.1-C.sub.8 alkoxyl, C.sub.2-C.sub.8 alkenyl, C.sub.3-C.sub.8 cycloalkyl, and C.sub.7-C.sub.16 aralkyl.

3. The moisture and radiation curable adhesive composition according to claim 1, wherein R.sub.10 is C.sub.1-C.sub.8 alkylene; and/or R.sub.11 is C.sub.6-C.sub.9 alkylene; and/or R.sub.12 is C.sub.1-C.sub.8 alkylene.

4. The moisture and radiation curable adhesive composition according to claim 1, wherein m is an integer of from 10 to 1800.

5. The moisture and radiation curable adhesive composition according to claim 1, wherein a is an integer of from 1 to 5, b is an integer of from 0 to 5, and c is an integer of from 0 to 5.

6. The moisture and radiation curable adhesive composition according to claim 1, wherein R.sub.14 to R.sub.21 are each independently selected from the group consisting of C.sub.1-C.sub.8 alkyl, C.sub.1-C.sub.8 alkoxyl, C.sub.2-C.sub.8 alkenyl, C.sub.3-C.sub.8 cycloalkyl, and C.sub.7-C.sub.16 aralkyl.

7. The moisture and radiation curable adhesive composition according to claim 1, wherein R.sub.14 to R.sub.21 are each independently selected from C.sub.1-C.sub.6 alkyl and C.sub.1-C.sub.6 alkoxyl.

8. The moisture and radiation curable adhesive composition according to claim 1, wherein R.sub.22 is C.sub.1-C.sub.8 alkylene; and/or R.sub.23 is C.sub.6-C.sub.9 alkylene; and/or R.sub.24 is C.sub.1-C.sub.8 alkylene.

9. The moisture and radiation curable adhesive composition according to claim 1, wherein d is an integer of from 1 to 5, e is an integer of from 0 to 5, and f is an integer of from 0 to 5.

10. The moisture and radiation curable adhesive composition according to claim 1, wherein the component (a) is present in an amount from 40 to 85% by weight, based on the total weight of all components.

11. The moisture and radiation curable adhesive composition according to claim 1, wherein the component (b) is present in an amount from 10 to 50% by weight, based on the total weight of all components.

12. The moisture and radiation curable adhesive composition according to claim 1, wherein the component (c) is present in an amount from 0.1 to 5% by weight, based on the total weight of all components.

13. The moisture and radiation curable adhesive composition according to claim 1, wherein the component (d) is present in an amount from 0.05 to 1% by weight, based on the total weight of all components.

14. The moisture and radiation curable adhesive composition according to claim 1, wherein the component (e) is present in an amount from 0 to 30% by weight, based on the total weight of all components.

15. The moisture and radiation curable adhesive composition according to claim 1, wherein the cured reaction product of the composition has a Shore 00 hardness of from 1 to 30, after 7 days from curing at 25° C., as measured according to ASTM D2240.

16. The moisture and radiation curable adhesive composition according to claim 1, wherein the cured reaction product of the composition has an elongation of from 100% to 300%, after 7 days from curing at 25° C., as measured according to ASTM D412.

17. The moisture and radiation curable adhesive composition according to claim 1, comprising: 40 to 85% by weight of component (a); 10 to 50% by weight of component (b); 0.1 to 5% by weight of component (c); 0.05 to 1% by weight of component (d); 1 to 30% by weight of component (e); and 0.05 to 1% by weight of component (f), wherein, the weight percentages are based on the total weight of all components.

18. The moisture and radiation curable adhesive composition according to claim 1, comprising: 45 to 80% by weight of component (a); 15 to 45% by weight of component (b); 1 to 3% by weight of component (c); 0.1 to 0.5% by weight of component (d); 3 to 25% by weight of component (e); and 0.1 to 0.5% by weight of component (f), wherein, the weight percentages are based on the total weight of all components.

19. A cured reaction product of the moisture and radiation curable adhesive composition according to claim 1.

20. A substrate which is coated on at least one surface with the moisture and radiation curable adhesive composition according to claim 1.

Description

DETAILED DESCRIPTION

[0043] It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present invention.

[0044] As used herein, the term “C.sub.1-C.sub.20 alkyl” refers to a monovalent linear or branched moiety containing only single bonds between carbon atoms in the moiety and including, for example, C.sub.1-C.sub.18-, C.sub.1-C.sub.12-, C.sub.1-C.sub.10-, C.sub.1-C.sub.8-, C.sub.1-C.sub.6- or C.sub.1-C.sub.4-alkyl. Examples thereof are methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, heptyl, 2,4,4-trimethylpentyl, 2-ethylhexyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-hexadecyl, n-octadecyl and n-eicosyl.

[0045] As used herein, “C.sub.2-C.sub.20 alkenyl group” refers to a straight or branched chain hydrocarbon having from two to twenty carbon atoms, with at least one unsaturation, and including, for example, C.sub.2-C.sub.18-, C.sub.2-C.sub.12-, C.sub.2-C.sub.10-, C.sub.2-C.sub.8-, C.sub.2-C.sub.6- or C.sub.2-C.sub.4-alkenyl. Typical examples are groups such as vinyl, allyl, 1-propen-2-yl, 1-buten-4-yl, 2-buten-4-yl and 1-penten-5-yl.

[0046] As used herein, the term “C.sub.1-C.sub.20 alkoxyl” refers to the group —O—R wherein R is C.sub.1-C.sub.20-alkyl as defined above, and including for example, C.sub.1-C.sub.18-, C.sub.1-C.sub.12-, C.sub.1-C.sub.10-, C.sub.1-C.sub.6- or C.sub.1-C.sub.4-alkoxyl.

[0047] As used herein, the term “C.sub.6-C.sub.20 aryl” refers to a monovalent unsaturated aromatic carbocyclic group of from 6 to 20 carbon atoms having a single ring (e.g., phenyl) or multiple condensed (fused) rings, wherein at least one ring is aromatic (e.g., naphthyl, dihydrophenanthrenyl, fluorenyl, or anthryl). Preferred examples include phenyl, naphthyl, phenantrenyl and the like.

[0048] As used herein, the term “C.sub.7-C.sub.22 alkylaryl” refers to aryl groups having from 7 to 22 carbon atoms and an alkyl substituent, including methyl phenyl, ethyl phenyl, methyl naphthyl, ethyl naphthyl, and the like.

[0049] As used herein, the term “C.sub.1-C.sub.20 alkylene” refers to a divalent linear or branched moiety containing only single bonds between carbon atoms in the moiety and including, for example, C.sub.1-C.sub.18-, C.sub.1-C.sub.12-, C.sub.1-C.sub.10-, C.sub.1-C.sub.6- or C.sub.1-C.sub.4-alkylene. Examples thereof are methylene, ethylene, propylene, isopropylene, n-butylene, sec-butylene, isobutylene, tert-butylene, n-pentylene, n-hexylene, n-heptylene, 2,4,4-trimethylpentylene, 2-ethylhexylene, n-octylene, n-nonylene, n-decylene, n-undecylene, n-dodecylene, n-hexadecylene, n-octadecylene and n-eicosylene.

[0050] As used herein, the term “C.sub.6-C.sub.20 arylene” refers to a divalent unsaturated aromatic carbocyclic group of from 6 to 20 carbon atoms having a single ring (e.g., phenylene) or multiple condensed (fused) rings, wherein at least one ring is aromatic (e.g., naphthylene, dihydrophenanthrenylene, fluorenylene, or anthrylene). Preferred examples include phenylene, naphthylene, phenantrenylene and the like.

[0051] As used herein, the term “(meth)acryloxy group” represents both acryloxy and methacryloxy group.

[0052] As used herein, the above groups may be further substituted or unsubstituted. When substituted, hydrogen atoms on the groups are replaced by substituent group(s) that is(are) one or more group(s) independently selected from alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, heteroaryl, heteroalicyclyl, aralkyl, heteroaralkyl, (heteroalicyclyl)alkyl, hydroxy, protected hydroxyl, alkoxy, aryloxy, acyl, ester, mercapto, alkylthio, arylthio, cyano, halogen, carbonyl, thiocarbonyl, O-carbamyl, N-carbamyl, O-thiocarbamyl, N-thiocarbamyl, C-amido, N-amido, S-sulfonamido, N-sulfonamido, C-carboxy, protected C-carboxy, O-carboxy, isocyanato, thiocyanato, isothiocyanato, nitro, silyl, sulfenyl, sulfinyl, sulfonyl, haloalkyl, haloalkoxy, trihalomethanesulfonyl, trihalomethanesulfonamido, and amino, including mono- and di-substituted amino groups, and the protected derivatives thereof. In case that an aryl is substituted, substituents on an aryl group may form a non-aromatic ring fused to the aryl group, including a cycloalkyl, cycloalkenyl, cycloalkynyl, and heterocyclyl.

[0053] All percentages, parts and ratios are based upon the total weight of the compositions of the present invention, unless otherwise specified. All such weights as they pertain to listed ingredients are based on the active level and, therefore, do not include carriers or by-products that may be included in commercially available materials.

[0054] In one aspect, the present disclosure is generally directed to a moisture and radiation curable adhesive composition, comprising following components: [0055] (a) at least one mono(meth)acryloxy terminated polyorganosiloxane represented by the formula:

##STR00003## [0056] wherein, [0057] R.sub.1 to R.sub.9 are each independently selected from the group consisting of C.sub.1-C.sub.20 alkyl, C.sub.1-C.sub.20 alkoxyl, C.sub.2-C.sub.20 alkenyl, C.sub.3-C.sub.20 cycloalkyl, and C.sub.7-C.sub.22 aralkyl, with the proviso that at least one of R.sub.1 to R.sub.9 is C.sub.1-C.sub.20 alkoxyl, [0058] m is an integer of from 1 to 1000, [0059] A.sub.1 is represented by the formula (2):

(R.sub.10).sub.a(R.sub.11).sub.b(R.sub.12).sub.cR.sub.13   (2) [0060] wherein: [0061] R.sub.10 is C.sub.1-C.sub.20 alkylene, [0062] R.sub.11 is C.sub.6-C.sub.21 arylene, [0063] R.sub.12 is C.sub.1-C.sub.20 alkylene, [0064] R.sub.13 is (meth)acryloxy, [0065] a is an integer of from 0 to 10, [0066] b is an integer of from 0 to 10, and [0067] c is an integer of from 0 to 10; [0068] (b) at least one di(meth)acryloxy terminated polyorganosiloxane represented by the formula:

##STR00004## [0069] wherein: [0070] R.sub.14 to R.sub.21 are each independently selected from the group consisting of C.sub.1-C.sub.20 alkyl, C.sub.1-C.sub.20 alkoxyl, C.sub.2-C.sub.20 alkenyl, C.sub.3-C.sub.20 cycloalkyl, and C.sub.7-C.sub.22 aralkyl, with the proviso that at least one of R.sub.1 to R.sub.9 is C.sub.1-C.sub.20 alkoxyl, [0071] n is an integer of from 1 to 1000, [0072] A.sub.2 and A.sub.3 are each independently represented by the formula:

(R.sub.22).sub.d(R.sub.23).sub.e(R.sub.24).sub.fR.sub.25   (4) [0073] wherein: [0074] R.sub.22 is C.sub.1-C.sub.20 alkylene, [0075] R.sub.23 is C.sub.6-C.sub.21 arylene, [0076] R.sub.24 is C.sub.1-C.sub.20 alkylene, [0077] R.sub.25 is (meth)acryloxy, [0078] d is an integer of from 0 to 10, [0079] e is an integer of from 0 to 10, and [0080] f is an integer of from 0 to 10; [0081] (c) a photoinitiator; [0082] (d) a moisture curing catalyst; [0083] (e) optionally, a chain extender; and [0084] (f) a moisture crosslinker.

Component (a)

[0085] The at least one mono(meth)acryloxy terminated polyorganosiloxane of the moisture and radiation curable adhesive composition comprised in the moisture and radiation curable adhesive composition according to the present invention is represented by the formula:

##STR00005##

[0086] In one embodiment, R.sub.1 to R.sub.9 are each independently selected from the group consisting of C.sub.1-C.sub.20 alkyl, C.sub.1-C.sub.20 alkoxyl, C.sub.2-C.sub.20 alkenyl, C.sub.3-C.sub.20 cycloalkyl, and C.sub.7-C.sub.22 aralkyl, with the proviso that at least one of R.sub.1 to R.sub.9 is C.sub.1-C.sub.20 alkoxyl.

[0087] Preferably, at least one of R.sub.1 to R.sub.3, R.sub.8 and R.sub.9 is C.sub.1-C.sub.8 alkoxyl, and the others of R.sub.1 to R.sub.9 are each independently selected from the group consisting of C.sub.1-C.sub.8 alkyl, C.sub.2-C.sub.8 alkenyl, C.sub.3-C.sub.8 cycloalkyl, and C.sub.7-C.sub.10 aralkyl. More preferably, at least one of R.sub.1 to R.sub.3, R.sub.8 and R.sub.9 is C.sub.1-C.sub.6 alkoxyl, and the others of R.sub.1 to R.sub.9 are each independently C.sub.1-C.sub.6 alkyl and C.sub.1-C.sub.6 alkoxyl, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, n-pentoxy, n-hexoxy, etc.

[0088] In one preferred embodiment, R.sub.1 to R.sub.7 are C.sub.1-C.sub.6 alkyl, preferably methyl, and R.sub.8 and R.sub.9 are C.sub.1-C.sub.6 alkoxyl, preferably methoxy.

[0089] In another embodiment, the index m is an integer of from 10 to 1800, preferably from 100 to 800, more preferably from 200 to 600.

[0090] In yet another embodiment, with respect to A.sub.1 represented by the formula (2):

(R.sub.10).sub.a(R.sub.11).sub.b(R.sub.12).sub.cR.sub.13   (2),

R.sub.10 is C.sub.1-C.sub.8 alkylene, preferably C.sub.1-C.sub.4 alkylene, more preferably methylene or ethylene. R.sub.11 is C.sub.6-C.sub.9 alkylene, preferably phenylene or naphthalene. R.sub.12 is C.sub.1-C.sub.8 alkylene, preferably C.sub.1-C.sub.4 alkylene, more preferably methylene or ethylene. R.sub.13 is (meth)acryloxy. The index a is an integer of from 1 to 5, preferably from 1 to 3, b is an integer of from 0 to 5, preferably from 0 to 3, and c is an integer of from 0 to 5, preferably from 0 to 3.

[0091] In one preferred embodiment, R.sub.10 is methylene, a is 3, b and c are 0, and thus A.sub.1 is (meth)acryloxypropyl group, preferably acryloxypropyl group.

[0092] In another preferred embodiment, R.sub.10 is ethylene, R.sub.11 is phenylene, R.sub.12 is methylene, a, b and c are 1, and thus A.sub.1 is (meth)acryloxymethylphenethyl group, preferably acryloxymethylphenethyl group.

[0093] According to the present invention, the moisture and radiation curable adhesive composition may comprises one or more mono(meth)acryloxy terminated polyorganosiloxanes each represented by formula (1). Preferably, the curable composition comprises one or two mono(meth)acryloxy terminated polyorganosiloxanes each represented by formula (1).

[0094] In the moisture and radiation curable adhesive composition according to the present invention, the component (a) is present in an amount from 40 to 85% by weight, preferably 45 to 80% by weight, based on the total weight of all components.

[0095] The mono(meth)acryloxy terminated polyorganosiloxane according to the present invention is prepared by conventional methods known in the art, for example as disclosed in U.S. Pat. No. 6,140,444 A, the content of which is incorporated by reference in its entirety.

[0096] More specifically, the process for preparing component (a) includes the steps of forming a mixture of a mono-silanol-terminated reactant, an alkoxysilane having (meth)acryloxy group, and organolithium catalyst, and reacting the mixture with agitation in the absence of moisture until the desired amount of silanol capping has occurred. Where substantially complete capping is desired, the equivalent ratio of silanol groups to alkoxysilane is preferably from about 1:0.95 to about 1:1.5, and more preferably from about 1:1 to about 1:1.2. Any volatile materials remaining in the reaction mixture after the capping has reached the required level can be removed by a mild heating under reduced pressure. An inert gas can be passed through the reaction mixture during the removal of the volatile materials.

[0097] The silanol-terminated reactant can be virtually any useful silanol-terminated material within the formula (5):

##STR00006##

wherein R.sub.26 to R.sub.28 are each independently selected from the group consisting of C.sub.1-C.sub.20 alkyl, C.sub.1-C.sub.20 alkoxyl, C.sub.2-C.sub.20 alkenyl, C.sub.3-C.sub.20 cycloalkyl, and C.sub.7-C.sub.22 aralkyl; and x is from about 1 to about 1,200, such as about 10 to about 1,000.

[0098] Preferably, R.sub.26 to R.sub.28 are each independently selected from the group consisting of C.sub.1-C.sub.8 alkyl, C.sub.1-C.sub.8 alkoxyl, C.sub.2-C.sub.8 alkenyl, C.sub.3-C.sub.8 cycloalkyl, and C.sub.7-C.sub.16 aralkyl. More preferably, R.sub.26 to R.sub.28 are each independently selected from C.sub.1-C.sub.6 alkyl and C.sub.1-C.sub.6 alkoxyl, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, n-pentoxy, n-hexoxy, etc. Most preferably, R.sub.26 to R.sub.28 are all methyl.

[0099] The viscosities of the mono-silanol-terminated organopolysiloxanes are within the range of from about 1 cps to about 150,000 cps, preferably from about 100 cps to about 10,000 cps measured using a Brookfield viscometer, at a temperature of about 25° C. (room temperature).

[0100] The alkoxysilane having (meth)acryloxy group includes a silane containing at least two alkoxy groups and at least one (meth)acryloxy group. More specifically, the alkoxysilane having (meth)acryloxy group includes at least one compound of the formula (5):

(R.sub.29).sub.a(R.sub.30).sub.bSi(OR.sub.31).sub.4-(a+b)   (6)

wherein R.sub.29 to R.sub.31 each independently selected from the group consisting of C.sub.1-.sub.20 alkyl, C.sub.2-20 alkyl and C.sub.6-20 aryl, preferably C.sub.1-6 alkyl, C.sub.2-6 alkyl and C.sub.6-14 aryl such as methyl, ethyl, n-propyl, isopropyl, phenyl, vinyl, and allyl groups. At least one of R.sub.29 and R.sub.30 is (meth)acryloxy group, and a is 0, 1 or 2; b is 0, 1 or 2; and a+b is 1 or 2.

[0101] Representative alkoxysilane having (meth)acryloxy group useful in the present invention include: (γ-acryloxymethyl)phenethyltrimethoxysilane, (γ-acryloxymethyptrimethoxysilane, (γ-acryloxypropyl)methylbis(trimethylsiloxy)silane, (γ-acryloxypropyl)methyldimethoxysilane, (γ-acryloxypropyl)methyldiethoxysilane, (γ-acryloxypropyl)trimethoxysilane, (γ-acryloxypropyl)tris(trimethylsiloxy)silane, (γ-methacryloxypropyl)bis(trimethylsiloxy)methylsilane, (γ-methacryloxymethyl)bis(trimethylsiloxy)methylsilane, (γ-nnethacryloxymethypmethyldimethoxysilane, (γ-methacryloxymethylphenethyl)tris(trimethylsiloxy)silane, (γ-methacryloxymethyl)tris(trimethylsiloxy)silane, (γ-methacryloxypropyl)methyldimethoxysilane, (γ-methacryloxypropyl)methyldiethoxysilane, (γ-methacryloxypropyl)triethoxysilane, (γ-methacryloxypropyl)triisopropoxysilane, (γ-methacryloxypropyl)trimethoxysilane, (γ-methacryloxypropyl)tris(methoxyethoxy)silane, (γ-methacryloxypropyl)tris(trinnethylsiloxy)silane.

[0102] Preferably, the alkoxysilane having (meth)acryloxy group is selected from (γ-acryloxymethyl)phenethyltrimethoxysilane, (γ-acryloxypropyl)trimethoxysilane, (γ-acryloxymethyl)trimethoxysilane, and combination thereof.

[0103] The organolithium reagent is preferably an alkyl lithium, such as methyl, n-butyl, sec-butyl, t-butyl, n-hexyl, 2-ethylhexyl and n-octyl lithium. Other useful catalysts include phenyl lithium, vinyl lithium, lithium phenylacetylide, lithium (trimethylsilyl) acetylide, lithium silanolates and lithium siloxanolates. The organo group can also be an amine-containing group, such as dimethylamine, diethylamine, diisopropylamine or dicyclohexylamine, or a silicone-containing group.

[0104] Generally, the amount of lithium in the reaction mixture is from 1 ppm to about 1000 ppm, preferably from about 5 ppm to about 500 ppm, such as from about 8 ppm to about 200 ppm, based on the weight of the reactants.

[0105] The amount of the organolithium catalyst used in the catalyst system depends on the reactivity of the silanol group-containing reactant and the reactivity of the alkoxysilane containing the polymerizable ethylenically unsaturated group. The amount chosen may be readily determined by those persons skilled in the art.

[0106] After the reaction, the organolithium catalyst can be reacted with carbon dioxide, precipitated as lithium carbonate and removed from the reaction mixture by liquid-solid separation means such as centrifuging, filtration and the like. Low molecular weight hydroxylamine and other low boiling point materials can be separated by heating the reaction mixture under reduced pressure.

[0107] The process can be carried out at temperatures of from about room temperature (about 25° C.) to about 150° C. The temperature at which the process is conducted depends on the particular reactants chosen, the identity and amount of the constituents of the catalyst system and the length of time the reaction can proceed.

Component (b)

[0108] The at least one di(meth)acryloxy terminated polyorganosiloxane of the moisture and radiation curable adhesive composition comprised in the moisture and radiation curable adhesive composition according to the present invention is represented by the formula:

##STR00007##

[0109] In one embodiment, R.sub.14 to R.sub.21 are each independently selected from the group consisting of C.sub.1-C.sub.2o alkyl, C.sub.1-C.sub.20 alkoxyl, C.sub.2-C.sub.20 alkenyl, C.sub.3-C.sub.20 cycloalkyl, and C.sub.7-C.sub.22 aralkyl, with the proviso that at least one of R.sub.1 to R.sub.9 is C.sub.1-C.sub.20 alkoxyl.

[0110] Preferably, at least one of R.sub.14, R.sub.15, R.sub.20 and R.sub.21 is C.sub.1-C.sub.8 alkoxyl, and the others of R.sub.14 to R.sub.21 are preferably each independently selected from the group consisting of C.sub.1-C.sub.8 alkyl, C.sub.2-C.sub.8 alkenyl, C.sub.3-C.sub.8 cycloalkyl, and C.sub.7-C.sub.16 aralkyl. More preferably, at least one of R.sub.14, R.sub.15, R.sub.20 and R.sub.21 is C.sub.1-C.sub.6 alkoxyl, and the others of R.sub.14 to R.sub.21 are each independently C.sub.1-C.sub.6 alkyl and C.sub.1-C.sub.6 alkoxyl, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, n-pentoxy, n-hexoxy, etc.

[0111] In one preferred embodiment, R.sub.16 to R.sub.19 are C.sub.1-C.sub.6 alkyl, preferably methyl, and R.sub.14, R.sub.15, R.sub.20 and R.sub.21 are C.sub.1-C.sub.6 alkoxyl, preferably methoxy.

[0112] In another embodiment, the index n is an integer of from 10 to 1800, preferably from 100 to 800, more preferably from 200 to 600.

[0113] In yet another embodiment, with respect to A.sub.2 and A.sub.3 each independently represented by the formula (7):

(R.sub.32).sub.d(R.sub.33).sub.e(R.sub.34).sub.fR.sub.35   (7),

R.sub.32 is C.sub.1-C.sub.8 alkylene, preferably C.sub.1-C.sub.4 alkylene, more preferably methylene or ethylene. R.sub.33 Is C.sub.6-C.sub.9 alkylene, preferably phenylene or naphthalene. R.sub.34 Is C.sub.1-C.sub.8 alkylene, preferably C.sub.1-C.sub.4 alkylene, more preferably methylene or ethylene. R.sub.35 is (meth)acryloxy. The index d is an integer of from 1 to 5, preferably from 1 to 3, e is an integer of from 0 to 5, preferably from 0 to 3, and f is an integer of from 0 to 5, preferably from 0 to 3.

[0114] In one preferred embodiment, R.sub.32 is methylene, d is 3, e and f are 0, and thus at least one of A.sub.2 and A.sub.3 is (meth)acryloxypropyl group, preferably acryloxypropyl group.

[0115] In another preferred embodiment, R.sub.32 is ethylene, R.sub.33 is phenylene, R.sub.34 is methylene, d, e and f are 1, and thus at least one of A.sub.2 and A.sub.3 is (meth)acryloxymethylphenethyl group, preferably acryloxymethylphenethyl group.

[0116] According to the present invention, the moisture and radiation curable adhesive composition may comprises one or more di(meth)acryloxy terminated polyorganosiloxanes each represented by formula (2). Preferably, the curable composition comprises one or two di(meth)acryloxy terminated polyorganosiloxanes each represented by formula (1).

[0117] In the moisture and radiation curable adhesive composition according to the present invention, the component (b) is present in an amount from 10 to 50% by weight, preferably 15 to 45% by weight, based on the total weight of all components.

[0118] The preparation method of di(meth)acryloxy terminated polyorganosiloxane may be similar to that of mono(meth)acryloxy terminated polyorganosiloxane as described above by replacing the monosilanol-terminated reactant with disilanol-terminated reactant represent by the formula (8):

##STR00008##

wherein, R.sub.36 and R.sub.37 are each independently selected from the group consisting of C.sub.1-C.sub.20 alkyl, C.sub.1-C.sub.20 alkoxyl, C.sub.2-C.sub.20 alkenyl, C.sub.3-C.sub.20 cycloalkyl, and C.sub.7-C.sub.22 aralkyl; and y is from about 1 to about 1,200, such as about 10 to about 1,000.

[0119] Preferably, R.sub.36 and R.sub.37 are each independently selected from the group consisting of C.sub.1-C.sub.8 alkyl, C.sub.1-C.sub.8 alkoxyl, C.sub.2-C.sub.8 alkenyl, C.sub.3-C.sub.8 cycloalkyl, and C.sub.7-C.sub.16 aralkyl. More preferably, R.sub.36 and R.sub.37 are each independently selected from C.sub.1-C.sub.6 alkyl and C.sub.1-C.sub.6 alkoxyl, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, n-pentoxy, n-hexoxy, etc. Most preferably, R.sub.32 and R.sub.33 are all methyl.

[0120] The viscosities of the mono-silanol-terminated organopolysiloxanes are within the range of from about 1 cps to about 150,000 cps, preferably from about 100 cps to about 10,000 cps measured using a Brookfield viscometer, at a temperature of about 25° C.

Component (c)

[0121] The moisture and radiation curable adhesive composition further comprises a photoinitiator to initiate the radiation curing, preferably UV curing of the composition upon receiving sufficient UV radiation.

[0122] There is no particular limitation to the photoinitiator useful in the present invention. Suitable photoinitiators include, but are not limited to, organic peroxides, azo compounds, quinones, benzophenones, nitroso compounds, acryl halides, hydrazones, mercapto compounds, pyrylium compounds, triacrylimidazoles, bisimidazoles, chloroalkyltriazines, benzoin ethers, benzil ketals, thioxanthones, acetophenones, acylphosphine oxides, alpha hydroxyl ketones, alpha amino ketones, derivatives of the aforementioned compounds, and mixtures thereof.

[0123] Exemplary photoinitiators are benzil ketals such as 2,2-dimethoxy-2-phenyl acetophenone (available from Ciba Specialty Chemicals under the trademark Irgacure 651); acetophenone derivatives such as 2,2-diethoxyacetophenone (“DEAP”, available from First Chemical Corporation); 2-hydroxy-2-methyl-1-phenyl-propan-1-one (“HMPP”, available from Ciba Specialty Chemicals under the trademark Darocur 1173); 1-hydroxy-cyclohexyl-phenyl ketone (available from Ciba Specialty Chemicals under the name Irgacure 184); 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone (available from Ciba Specialty Chemicals under the trademark Irgacure 369); 2-methyl-1-(4-(methylthio)phenyl)-2-morpholinopropan-1-one (available from Ciba Specialty Chemicals under the trademark Irgacure 907); or acylphosphine oxides such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide (“TPO”, available from Ciba Specialty Chemicals in 50/50 wt % blends with HMPP (as Irgacure 4265)), bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide (available from Ciba Specialty Chemicals in the form of blends with other ketones including: 25/75 wt % blend with HMPP as Irgacure 1700, and 1-hydroxy-cyclohexyl-phenyl-ketone, (or HCPK) as Irgacure 1850 or 1800 depending on proportions), or bis(2,4,6-trimethylbenzoyfl)-phenylphosphine oxide (available from Ciba Specialty Chemicals under the trademark Irgacure 819).

[0124] In one preferred embodiment, the photoinitiator useful in the present invention is selected from the group consisting of 2-hydroxy-2-methyl-1-phenyl-propan-1-one, bis(2,4,6-trimethylbenzoyfl)-phenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl ketone, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, and the combination thereof. More preferably, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-propan-1-one.

[0125] In the moisture and radiation curable adhesive composition according to the present invention, the component (d) is present in an amount from 0.1 to 5% by weight, preferably 1 to 3% by weight, based on the total weight of all components.

Component (d)

[0126] The moisture and radiation curable adhesive composition further comprises a moisture curing catalyst which initiates the moisture curing of the composition in the presence of moisture.

[0127] The moisture curing catalysts typically used in the moisture and radiation curable adhesive compositions of this invention include those known to be useful for facilitating moisture curing. The catalysts include metal and non-metal catalysts. Examples of the metal portion of the metal catalysts useful in the present invention include tin, titanium, zirconium, lead, iron cobalt, antimony, manganese, bismuth and zinc compounds.

[0128] In one embodiment, the tin compounds useful for facilitating the moisture curing of the composition include but are not limited to dimethyldineodecanoatetin (available from Momentive Performance Materials Inc. under the trade name of FOMREZ UL-28 A), dibutyltindilaurate, dibutyltindiacetate, dibutyltindimethoxide, tinoctoate, isobutyltintriceroate, dibutyltinoxide, solubilized dibutyl tin oxide, dibutyltin bis diisooctylphthalate, bis-tripropoxysilyl dioctyltin, dibutyltin bis-acetylacetone, silylated dibutyltin dioxide, carbomethoxyphenyl tin tris-uberate, isobutyltin triceroate, dimethyltin dibutyrate, dimethyltin di-neodecanoate, triethyltin tartarate, dibutyltin dibenzoate, tin oleate, tin naphthenate, butyltintri-2-ethylhexylhexoate, tinbutyrate, dioctyltin didecylmercaptide, bis(neodecanoyloxy)dioctylstannane, dimethylbis(oleoyloxy)stannane.

[0129] In one preferred embodiment, the moisture curing catalyst is selected from the group consisting of dimethyldineodecanoatetin (available from Momentive Performance Materials Inc. under the trade name of FOMREZ UL-28), dioctyltin didecylmercaptide (available from Momentive Performance Materials Inc. under the trade name of FOMREZ UL-32), bis(neodecanoyloxy)dioctylstannane (available from Momentive Performance Materials Inc. under the trade name of FOMREZ UL-38), dimethylbis(oleoyloxy)stannane (available from Momentive Performance Materials Inc. under the trade name of FOMREZ UL-50), and combination thereof. More preferably, the moisture curing catalyst is FOMREZ UL-28.

[0130] In the moisture and radiation curable adhesive composition according to the present invention, the component (d) is present in an amount from 0.05 to 1% by weight, preferably 0.1 to 0.5% by weight, based on the total weight of all components.

Component (e)

[0131] The moisture and radiation curable adhesive composition may optionally comprises a chain extender.

[0132] There is no particular limitation to the chain extender useful in the present invention, and it includes but is not limited to methoxy, ethoxy, triethoxysilylethyl terminated polydimethylsiloxanes, etc. Exemplary chain extenders are methoxy terminated polydimethylsiloxanes such as DMS-XM11 (available from Gelest, Inc., Morrisville, Pa.), dimethoxy(epoxypropoxypropyl) terminated polydimethylsiloxanes such as DMS-EX21 (available from Gelest, Inc., Morrisville, Pa.), ethoxy terminated dimethylsiloxanes such as DMS-XE11 (available from Gelest, Inc., Morrisville, Pa.), and triethoxysilylethyl terminated polydimethylsiloxanes such as DMS XT11 (available from Gelest, Inc., Morrisville, Pa.).

[0133] The component (e) is present in an amount from 0 to 30% by weight, preferably 0 to 25% by weight, based on the total weight of all components of the moisture and radiation curable adhesive composition according to the present invention.

Component (f)

[0134] The moisture and radiation curable adhesive composition may optionally comprises a moisture crosslinker.

[0135] Exemplary moisture crosslinker are vinyltrichiorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, p-styryltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-2-(aminoethyl)-γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, dimethoxy-3-mercaptopropylmethylsilane, 2-(2-aminoethylthioethyl)diethoxymethylsilane, 3-(2-acetoxyethylthiopropyl)dimethoxymethylsilane, 2-(2-aminoethylthioethyl)triethoxysilane, dimethoxymethyl-3-(3-phenoxypropylthiopropyl)silane, bis(triethoxysilylpropyl)disulfide, bis(triethoxysilylpropyl)tetrasulfide, 1,4-bis(triethoxysilyl)benzene, bis(triethoxysilyl)ethane, 1,6-bis(trimethoxysilyl)hexane, 1,8-bis(triethoxysilyl)octane, 1,2-bis(trimethoxysilyl)decane, bis(triethoxysilylpropyl)amine, bis(trimethoxysilylpropyl)urea, tris-(3-trimethoxysilylpropyl)isocyanurate, γ-chloropropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, trimethylsilanol, diphenylsilanediol, triphenylsilanol, γ-triethoxysilylpropyl(meth)acrylate, and hexyltrimethoxysilane.

[0136] Preferably, the moisture and radiation curable adhesive composition contains a moisture crosslinker, and the moisture crosslinker is selected from the group consisting of vinyltrimethoxysilane, 1,6-bis(trimethoxysilyl)hexane, 1,8-bis(trimethoxysilyl)octane, γ-(meth)acryloxypropyltrimethoxysilane, and combination thereof. More preferably, the moisture crosslinker is vinyltrimethoxysilane available from Evonik under the trade name of Dynasylan VTMO.

[0137] The component (f) is present in an amount from 0 to 1% by weight, preferably 0 to 0.5% by weight based on the total weight of all components.

[0138] In one embodiment, the present invention provides a moisture and radiation curable adhesive composition comprising: [0139] 40 to 85% by weight, preferably 45 to 80% by weight of component (a); [0140] 10 to 50% by weight, preferably 15 to 45% by weight of component (b); [0141] 0.1 to 5% by weight, preferably 1 to 3% by weight of component (c); [0142] 0.05 to 1% by weight, preferably 0.1 to 0.5% by weight of component (d); [0143] 1 to 30% by weight, preferably 3 to 25% by weight of component (e); and [0144] 0.05 to 1% by weight, preferably 0.1 to 0.5% by weight of component (f),
wherein, the weight percentages are based on the total weight of all components.

Other Components

[0145] The moisture and radiation curable adhesive composition may further comprise one or more optional additives, resin components and the like to improve or modify properties of the sealant composition, such as flowability, dispensing property, storage stability, curing property and physical property of the cured product.

[0146] The components that may be contained in the sealant composition as needed include, but are not limited to, for example, organic or inorganic filler, thixotropic agent, diluent, modifier, coloring agent such as pigment and dye, preservative, stabilizer, plasticizer, lubricant, defoamer, leveling agent and the like.

[0147] Suitable fillers, which can be optionally used in the present invention includes, but are not limited to, inorganic fillers such as silica, diatomaceous earth, alumina, zinc oxide, iron oxide, magnesium oxide, tin oxide, titanium oxide, magnesium hydroxide, aluminium hydroxide, magnesium carbonate, barium sulphate, gypsum, calcium silicate, talc, glass bead, sericite activated white earth, bentonite, aluminum nitride, silicon nitride, and the like; organic fillers, such as polymethyl methacrylate, polyethyl methacrylate, polypropyl methacrylate, polybutyl methacrylate, poly acrylonitrile, polystyrene, polybutadiene, polypentadiene, polyisoprene, polyisopropylene, and the like. The filler may be used alone or in combination thereof.

[0148] Suitable thixotropic agents, which can be optionally used in the present invention includes, but are not limited to, talc, fume silica, superfine surface-treated calcium carbonate, fine particulate alumina, plate-like alumina; layered compound such as montmorillonite, spicular compound such as aluminium borate whisker, and the like. Talc, fume silica and fine alumina are preferred thixotropic agents.

The Moisture and Radiation Curable Adhesive Composition

[0149] The moisture and radiation curable adhesive composition of the present invention is in the form of liquid, and the Brookfield viscosity of the composition is preferably about 50 cps to about 40,000 cps at 25° C. The liquid adhesive composition in such range of viscosity has a good flowing property which makes it easy to be applied or injected onto a substrate. The Brookfield viscosity here is measured by using a Brookfield rotational viscometer (digital Brookfield viscometer, DV-II+, available from BROOKFIELD, US) with spindles at 25° C. according to ASTM D1084-1997. The selection of spindle for testing will depend on the level of the viscosity of the adhesive composition.

Preparation of the Moisture and Radiation Curable Adhesive Composition

[0150] A mixer equipped with a mechanical stirrer, condenser, thermometer, heating mantle, nitrogen inlet, and an addition funnel is charged with components (a) and (b), and heated up to 80° C. The contents are mixed at 120 rpm under vacuum for 3 hours, then cooled under vacuum to room temperature. The component (c), component (d) and optionally components (e) and (f) are then added to the mixer under vacuum. The vacuum is broken with nitrogen after 1 hour of mixing for all components.

Process of Bonding Substrates

[0151] Another aspect of the present invention provides a process of bonding substrates, comprising, [0152] (i) applying the moisture and radiation adhesive composition according to the present invention onto the substrate to be bonded; [0153] (ii) laminating or stacking the substrate to be bonded to form an assembly; [0154] (iii) photo irradiating the assembly; and [0155] (iv) placing the assembly under ambient conditions.

[0156] Specifically, the adhesive composition according to the present invention may be coated under pressure onto the surface of the substrate following the predetermined route by means of the needle cylinder of an automatic dispensing system. Subsequently, another substrate is laminated onto the adhesive, and the height difference between the two substrates is controlled by a dispenser, e.g., Dispenser KAR03, manufactured by IINUMA-GAUGE MFG LTD. After the adhesive is self-leveled on the whole bonding area, photo irradiation is conducted from top to bottom for curing. Light source (such as ultraviolet light and visible light) and high energy ray (such as electronic beam, α-ray, γ-ray and X-ray) can be used herein for photo irradiation, with preference given to ultraviolet light in the wavelength range of about 200 nm to about 400 nm. The energy dose is 3000 mJ/cm.sup.2 or more, the power intensity is about 50 to about 100 mW/cm.sup.2. The UV lamp used may be such as Loctite UVALOC 1000, and the irradiation time may generally be about 5 s to about 120 s. Since the marginal areas are within the nontransparent part, it cannot be cured by UV irradiation. The bonded parts can be completely cured by storing the parts at room temperature for about 24 hours, according to the moisture-curable character of the present adhesive composition, without any need for additional equipment and processing.

The Cured Adhesive Product

[0157] Another aspect of the present invention also provides a cured adhesive product produced from the moisture and radiation curable adhesive composition.

[0158] Surprisingly, the cured adhesive product of the adhesive composition according to the present invention is very soft and specifically exhibited a lower Shore 00 hardness and improved elongation, meanwhile maintaining excellent properties including good stability under high temperature and humidity and high transparency. As such, the cured adhesive product is suitable to be used in display panels, touch panels and optical devices, and can significantly decrease the shrinkage and absorb the stress built up in the substrate, which is known as the cause of the Mura effect.

[0159] In one embodiment, the cured reaction product of the composition has a Shore 00 hardness of from 1 to 30, preferably from 5 to 25, after 7 days from curing, at 25° C., as measured according to ASTM D2240.

[0160] In another embodiment, the cured reaction product of the composition has an elongation of from 100% to 300%, preferably 110% to 250%, after 7 days from curing, at 25° C., as measured according to ASTM D412.

Use of the Moisture and Radiation Curable Adhesive Composition

[0161] The moisture and radiation curable adhesive composition of the present invention may be used as a liquid optical clear adhesive (LOCA) for handheld device and display (HHDD), especially for bonding or laminating various elements in the manufacture of display panels, touch panels and optical devices.

[0162] For example, the moisture and radiation curable adhesive composition of the present invention can be used in bonding or laminating a transparent substrate with another transparent substrate, or bonding or laminating a transparent substrate with a non-transparent substrate. The transparent substrate comprises glass and transparent plastic etc., and the non-transparent substrate comprises metal, non-transparent plastic, ceramic, stone, leather and wood etc. Plastic may be for example poly(methyl methacrylate) (PMMA), polycarbonate (PC) or polyester (PET) etc.

EXAMPLE

Synthesis of MDMA-1000

[0163] A 5 liter, 4-neck round bottom flask equipped with mechanical stirrer, heating mantle, sparge tube and thermometer was charged with 2425 g of a ω-hydroxyl terminated polydimethylsiloxane (having a viscosity of 1000 cps, commercially available from AB Specialty Silicones under the trade name of MOH 1000). The fluid was heated to a temperature of 60° C. and sparged with nitrogen for a period of time of 30 minutes followed by vacuum for another 30 minutes to remove any volatile components such as water and carbon dioxide. γ-Acryloxypropyltrimethoxysilane (“APTMS”, 36 g, commercially available from Gelest) and n-butyl lithium in hexane solution (1.6M; 1.89 ml, commercially available from Sigma-Aldrich) were sequentially added to the reactor. The mixture was maintained at a temperature of 60° C. under vacuum for a period of time of 3 hours. Dry ice (1 g) was then added to the reaction mixture to quench the catalyst. The mixture was vacuum stripped to remove the volatile components. The final product is a monoacryloxypropyldimethoxysilyl-terminated PDMS, and designated as MDMA-1000 in the present invention.

Synthesis of MDMA-100

[0164] A 1 gallon reactor equipped with mechanical stirrer, heating/cooling jacket was charged with 2500 g of a w-hydroxyl terminated polydimethylsiloxane (having a viscosity of 100 cps, commercially available from AB Specialty Silicones under the trade name of MOH 100). The fluid was heated to a temperature of 80° C. and vacuum was applied for 60 minutes to remove any volatile component such as water and carbon dioxide. APTMS (111 g, commercially available from Gelest) and n-butyl lithium in hexane solution (1.6M; 2.0 ml, commercially available from Sigma-Aldrich) were sequentially added to the reactor. The mixture was maintained at a temperature of 80° C. under vacuum for a period of time of 3 hours. Dry ice (1 g) was then added to the reaction mixture to quench the catalyst. The mixture was vacuum stripped to remove the volatile components. The final product is a monoacryloxypropyldimethoxysilyl-terminated PDMS, and designated as MDMA-100 in the present invention.

Synthesis of DMA-4000

[0165] A 1 gallon reactor equipped with mechanical stirrer, heating/cooling jacket was charged with 2300 g of an α,ω-hydroxyl terminated polydimethylsiloxane (having a viscosity of 4000 cps, commercially available from Emerald Performance Materials under the trade name of Masil SFR 3500) The fluid was heated to a temperature of 60° C. and vacuum was applied for 60 minutes to remove any volatile component such as water and carbon dioxide. APTMS (65 g, commercially available from Gelest) and n-butyl lithium in hexane solution (1.6M; 1.8 ml, commercially available from Sigma-Aldrich) were sequentially added to the reactor. The mixture was maintained at a temperature of 60° C. under vacuum for a period of time of 3 hours. Dry ice (1 g) was then added to the reaction mixture to quench the catalyst. The mixture was vacuum stripped to remove the volatile components. The final product is a diacryloxypropyldimethoxysilyl-terminated PDMS, and designated as DMA-4000 in the present invention.

Synthesis of DMA-6000

[0166] A 2-gallon reactor equipped with mechanical stirrer, heating/cooling jacket was charged with 4932.5 g of an a,w-hydroxyl terminated polydimethylsiloxane (having a viscosity of 6000 cps, commercially available from Emerald Performance Materials under the trade name of Masil SFR 6000). The fluid was heated to a temperature of 50° C. and vacuum was applied for 60 minutes to remove any volatile component such as water and carbon dioxide. APTMS (65 g, commercially available from Gelest) and n-butyl lithium in hexane solution (1.6M; 3.9 ml, commercially available from Sigma-Aldrich) were sequentially added to the reactor. The mixture was maintained at a temperature of 50° C. under vacuum for a period of time of 4 hours. Dry ice (1 g) was then added to the reaction mixture to quench the catalyst. The mixture was vacuum stripped to remove the volatile components. The final product is a diacryloxypropyldimethoxysilyl-terminated PDMS, and designated as DMA-6000 in the present invention.

Synthesis of Chain Extender

[0167] A 2-gallon reactor equipped with mechanical stirrer, heating/cooling jacket was charged with 4400 g of an a,w-hydroxyl terminated polydimethylsiloxane (having a viscosity of 70 cps, commercially available from Emerald Performance Materials under the trade name of Masil SFR 70). The fluid was heated to a temperature of 60° C. and vacuum was applied for 60 minutes to remove any volatile component such as water and carbon dioxide. Dimethyldimethoxysilane (320 g, commercially available from Gelest) and n-butyl lithium in hexane solution (1.6M; 3.64 ml, commercially available from Sigma-Aldrich) were sequentially added to the reactor. The mixture was maintained at a temperature of 60° C. under nitrogen protection for a period of time of 3 hours. Dry ice (1 g) was then added to the reaction mixture to quench the catalyst. The mixture was vacuum stripped to remove the volatile components. The final product will be used as the chain extender in the examples.

[0168] Following the above preparation process, adhesive compositions according to the present invention and a comparative example were obtained. Names and amounts of the components are listed in Table 1.

TABLE-US-00001 TABLE 1 The compositions of Examples A to G (Ex. A to Ex. G) Amount (wt %) Ex. Ex. Ex. Ex. Ex. Ex. Ex. Component A B C D E F G MDMA-100  — 65.8 — — 20 50.8 — MDMA-1000 60 — 45.8 75.8 30.8 20 — DMA-4000 — 25 20 — 10 25 — DMA-6000 25.8 — 20 20 15 — 95.8 Photoinitiator.sup.1 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Moisture 0.2 0.2 0.2 0.2 0.2 0.2 0.2 catalyst.sup.2 Chain extender.sup.3 10 5 10 — 20 — — Moisture 2.0 2.0 2.0 2.0 2.0 2.0 2.0 crosslinker.sup.4 .sup.1Photoinitiator: 2-hydroxy-2-methyl-1-phenyl-propan-1-one, commercially available from Ciba Specialty Chemicals under the trade name of Darocur 1173. .sup.2Moisture catalyst: dimethyldineodecanoatetin, commercially available from Momentive Performance Materials Inc. under the trade name of FOMREZ UL-28. .sup.3Chain extender: linear structured PDMS end-capped with methoxy groups synthesized as above. .sup.4Moisture crosslinker: vinyltrimethoxysilane available from Evonik under the trade name of Dynasylan VTMO.

[0169] For the tests, all components (with a total amount about 50 grams) were added to a plastic jar which was then spanned 3 times in a speed mixer at 3000 rpm for 30 seconds each time. 32 grams of the material was poured into 6 inches×6 inches metal frame with a polyethylene film and a piece of glass on each side, followed by a 60 second UV exposure from both sides with UVA intensity at 75 mW/cm.sup.2. The polyethylene films were peeled off and the cured products to be tested were then kept in a 25° C., 50% relative humidity chamber for 7 days.

[0170] The hardness according to ASTM D2240 and the elongation according to ASTM D412 of the cured products of the compositions in Table 1 are listed in Table 2.

TABLE-US-00002 TABLE 2 Test results of the examples Results Ex. Ex. Ex. Ex. Ex. Ex. Ex. Test A B C D E F G Shore 00 5 7 10 15 20 25 68 Hardness Elongation 240 110 190 140 310 130 75 (%) After 7 day at 25° C.

[0171] As shown in Table 1, Examples A to F are inventive examples of adhesive compositions having at least one mono(meth)acryloxy terminated polyorganosiloxane and at least one di(meth)acryloxy terminated polyorganosiloxane. Example G only comprises one di(meth)acryloxy terminated polyorganosiloxane, and listed as a comparative example which is a typical example of traditional adhesive formulations.

[0172] As demonstrated in Table 2, the Shore 00 hardness results of the cured products of Examples A to F are in the range of 5 to 25, which is significantly lower than the range (50 to 70) of traditional UV and moisture curing silicone based adhesives, e.g. Example G.

[0173] It is also clear in Table 2 that elongation results of the cured products of Examples A to F are much larger than that of Example G, which indicates that the inventive adhesive compositions are much softer than traditional formulations.

[0174] It is believed that such excellent results are due to the assumption that the combination of silicones with different curing densities brings about the free volume in the polymer which allows the polymer chain to move even after the dual cure is completed. Therefore, the stress built up in the substrates during assembly and long term thermal cycles can be largely absorbed and decreased by the inventive adhesives, and in turn Mura effect will be avoided. In addition, the softer adhesive can be used in displays as a shock absorber to increase the durability of the devices.

[0175] In addition, the inventive adhesives also exhibited properties including good adhesion to different substrates, good transmittance, good stability under room temperature, high temperature and high humidity.