Dual cure organopolysiloxane composition with shelf life stability

Abstract

[Problem] The purpose of the present invention is to provide a dual-curable organopolysiloxane composition which combines both photocuring and curing ability by exposure to moisture, exhibits excellent curability and long-term storage stability under room temperature or environmental storage conditions, and has excellent adhesion to a silicone resin, a silicone resin, and a silicone resin composition. And preferably is applied in a solvent-free form. [Solution] A dual-curing organopolysiloxane composition comprising: (A) an organopolysiloxane having an average of one or more alkenyl groups per molecule and an average of one or more hydrolysable groups per molecule; (B) an organopolysiloxane having an average of two (2) or more photoreactive groups per molecule; (C) a condensation reaction catalyst; (D) a combination of the following photoinitiators (d1) to (d3); (d1) a 2, 4, 6-trimethylbenzoyl phenyl phosphinate, (d2) bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide, and (d3) 2, 2-dimethoxy-1, 2-diphenylethyl-1-one (E) a silane having an average of 2 or more hydrolysable groups per molecule, (d1) a 2, 4, 6-trimethylbenzoyl phenyl phosphinate, (d2) bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide, and (d3) 2, 2-dimethoxy-1, 2-diphenylethyl-1-one (E) a silane having an average of 2 or more hydrolysable groups per molecule; and optionally, (F) a free radical scavenger.

Description

Technical Field

[0001] The present invention relates to an organopolysiloxane composition that can be cured by both ultraviolet (UV) and moisture-induced curing. In particular, the organopolysiloxane composition is excellent in its storage stability and is preferably used as a solventless composition that substantially does not use organic solvents. Background Art

[0002] The application of the dual-curable organopolysiloxane composition in electronic products is expanding because the dual-curable organopolysiloxane composition using UV light and moisture curing mechanisms brings immediate curing benefits through primary UV curing and moisture curing for secondary shadow area curing.

[0003] For example, Patent Document 1 discloses a dual-curable organopolysiloxane composition. This reference discloses a composition that can be particularly used for conformal coatings in electronic applications, in which the substrate has a shielding area that is not easily accessible to direct UV light and requires moisture curing to crosslink those areas. Generally, in addition to the presence of a photoinitiator for radiation polymerization, there is also a condensation catalyst, such as an organic titanate or an organic tin. In the absence of a condensation catalyst, moisture curing generally does not occur with any degree of certainty or within any predictable time range. Therefore, as a practical matter, the moisture curing aspect of these compositions would be impractical for commercial use in the absence of a condensation catalyst. In addition, the composition lacks storage stability at room temperature or ambient storage conditions.

[0004] Similarly, solvent-based dual-curable organopolysiloxane compositions are proposed in Patent Document 2 and Patent Document 3. The thiol-ene reaction by UV irradiation and the moisture curing reaction by alkoxy condensation with a titanium catalyst provide good curing performance and physical properties in the fresh state. However, during its storage period, it requires storage under low temperature or freezer conditions to maintain its curing performance and properties. This specific low-temperature storage condition is good for maintaining its performance, but it will provide other limitations, such as increased storage costs and additional inputs for manufacturers and users, with negative sustainability. In addition, these compositions cannot be used for solventless compositions and coating / adhesive applications.

[0005] The thiol-ene-based UV and moisture dual-curing system generally has a relatively short storage period compared to the only moisture curing system or the only thiol-ene UV curing silicone system. The storage period can be evaluated by determining whether the composition has experienced an increase in viscosity and / or a decrease in curing depth during UV curing and / or an increase in the time to reach a tack-free surface through moisture curing relative to when the composition is freshly prepared.

[0006] Patent Documents 4 and 5 attempt to solve the shelf life problem of thiol-ene dual-curing formulations by providing a thiol-ene dual-curing organopolysiloxane system that requires an epoxide to stabilize the formulation.

[0007] However, the dual-curing organopolysiloxane compositions disclosed in the foregoing patent documents lack long-term storage stability and shelf life at room temperature or ambient storage conditions. In addition, it would be desirable to provide a solvent-free (i.e., substantially free of organic solvents) dual UV-curable, moisture-curable silicone composition in which the composition is cured by UV to obtain a coating that is dry to the touch and does not have the common tacky surface typically associated with acrylate curing.

[0008] [Prior art documents]

[0009] [Patent documents]

[0010] Patent Document 1: U.S. Patent No. 4,528,081

[0011] Patent Document 2: U.S. Patent No. 6,828,355

[0012] Patent Document 3: WO2006 / 060189A2

[0013] Patent Document 4: WO2019 / 005393A1

[0014] Patent Document 5: WO2020 / 076620A1 SUMMARY OF THE INVENTION

[0015] Technical problem

[0016] An object of the present invention is to provide a dual-curing organopolysiloxane composition that has both the ability to cure by light and to cure by exposure to moisture, exhibits excellent curability and long-term storage stability at room temperature or ambient storage conditions, and is preferably applied in a solvent-free form.

[0017] Solution to the problem

[0018] Through in-depth research, the present inventors have found that the above problems can be solved by a dual-curing organopolysiloxane composition comprising:

[0019] (A) an organopolysiloxane having an average of one or more alkenyl groups per molecule and an average of one or more hydrolyzable groups per molecule;

[0020] (B) an organopolysiloxane having an average of two (2) or more photo-reactive groups per molecule;

[0021] (C) Condensation reaction catalyst;

[0022] (D) A combination of the following photoinitiators (d1) to (d3);

[0023] (d1) 2,4,6-Trimethylbenzoyl phenylphosphinate,

[0024] (d2) Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and

[0025] (d3) 2,2-Dimethoxy-1,2-diphenylethan-1-one,

[0026] (E) A silane having an average of 2 or more hydrolyzable groups per molecule; and optionally,

[0027] (F) A radical scavenger.

[0028] In various embodiments, when the total mass of components (d1) to (d3) is 100% by mass, the mass ratio of components (d1) to (d3) is within the following ranges:

[0029] The mass ratio of component (d1) is within the range of 10% by mass to 30% by mass,

[0030] The mass ratio of component (d2) is within the range of 20% by mass to 40% by mass, and

[0031] The mass ratio of component (d3) is within the range of 40% by mass to 80% by mass.

[0032] In certain embodiments, the composition derives from a UV radiation curing mechanism and a moisture curing mechanism.

[0033] In certain embodiments, the composition is substantially free of organic solvents, i.e., a "solvent-free" composition.

[0034] In certain embodiments, the composition is used as a potting compound (or potting agent), coating, adhesive, or encapsulant.

[0035] Advantageous effects of the present invention

[0036] The dual-curable organopolysiloxane composition according to the present disclosure generally has both the ability to be photocured and cured by exposure to moisture, and exhibits good to excellent curability and long-term storage stability at room temperature or ambient storage conditions. In addition, the composition of the present invention can be easily applied in the form of a "solvent-free" composition having excellent coating ability and appropriate viscosity. Detailed Description

[0037] The term "comprising" is used in its broadest sense herein and means and encompasses the concepts of "including", "consisting essentially of", and "consisting of". The use of "for example", "such as", and "including" to list exemplary examples does not mean being limited to the examples listed. Thus, "for example" or "such as" means "for example, but not limited to" or "such as, but not limited to" and encompasses other similar or equivalent examples. The term "about" as used herein is used to reasonably cover or describe minor variations in values measured by instrumental analysis or as a result of sample handling. Such minor variations can be about ±0 - 25%, ±0 - 10%, ±0 - 5%, or ±0 - 2.5% of the value. Additionally, the term "about" applies to both values when associated with a range of values. Further, the term "about" applies to a value even when not explicitly stated.

[0038] Generally speaking, as used herein, the hyphen "-" or dash "-" within a range of values means "to" or "until"; ">" means "higher than" or "greater than"; "≥" means "at least" or "greater than or equal to"; "<" means "lower than" or "less than"; and "≤" means "at most" or "less than or equal to". Each of the foregoing patent applications, patents, and / or patent application publications is hereby incorporated by reference in its entirety in one or more non-limiting embodiments.

[0039] It should be understood that the appended claims are not limited to the specific and particular compounds, compositions, or methods described in the specific embodiments, which may vary between specific embodiments falling within the scope of the appended claims. With respect to any Markush group relied upon herein to describe specific features or aspects of various embodiments, it should be understood that different, special, and / or unexpected results can be obtained from each member of the corresponding Markush group independent of all other Markush members. Each member of the Markush group can be relied upon individually and / or in combination and provides sufficient support for specific embodiments within the scope of the appended claims.

[0040] It should also be understood that any ranges and sub-ranges relied upon in describing various embodiments of the present invention independently and collectively fall within the scope of the appended claims, and it should be understood that all ranges, including integral values and / or fractional values therein, are described and contemplated, even if such values are not explicitly written herein. Those skilled in the art will readily recognize that the recited ranges and sub-ranges fully describe and enable the various embodiments of the present invention, and such ranges and sub-ranges can be further delineated into related one-half, one-third, one-fourth, one-fifth, etc. By way of example only, the range of "0.1 to 0.9" can be further delineated into the lower one-third (i.e., 0.1 to 0.3), the middle one-third (i.e., 0.4 to 0.6), and the upper one-third (i.e., 0.7 to 0.9), which independently and collectively fall within the scope of the appended claims and can be independently and / or collectively relied upon and provide sufficient support for specific embodiments within the scope of the appended claims. In addition, with respect to language that defines or modifies a range, such as "at least," "greater than," "less than," "not exceeding," etc., it should be understood that such language includes sub-ranges and / or upper or lower limits. As another example, the range of "at least 10" inherently includes sub-ranges of at least 10 to 35, at least 10 to 25, 25 to 35, etc., and each sub-range can be independently and / or collectively relied upon and provide sufficient support for specific embodiments within the scope of the appended claims. Finally, the individual numbers within the disclosed ranges can be relied upon and provide sufficient support for specific embodiments within the scope of the appended claims. For example, the range of "1 to 9" includes individual integers such as 3, as well as individual numerical values including a decimal point (or fraction) such as 4.1, which can be relied upon and provide sufficient support for specific embodiments within the scope of the appended claims.

[0041] <Doubly curable organopolysiloxane composition>

[0042] Component (A) is an organopolysiloxane having on average one or more alkenyl groups per molecule and on average one or more hydrolyzable groups per molecule. Examples of alkenyl groups include vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, and dodecenyl group. In certain embodiments, from the perspective of economy and reactivity, there is at least one of vinyl group, allyl group, hexenyl group, and octenyl group. Specifically, in view of the excellent UV curability of the composition, component (A) may have at least two alkenyl groups per molecule.

[0043] Examples of the hydrolyzable group include alkoxy groups such as methoxy group, ethoxy group, propoxy group and butoxy group. In certain embodiments, from the perspective of economy and curability, there is at least one of methoxy group and ethoxy group. Specifically, according to the composition having excellent moisture curability, component (B) may have at least two alkoxy groups bonded to silicon atoms per molecule.

[0044] In addition, examples of the group bonded to the silicon atom in component (A) other than the alkenyl group and the alkoxy group include: alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group and the like; aryl groups having 6 to 12 carbon atoms such as phenyl group, tolyl group, xylyl group and the like; aralkyl groups having 7 to 12 carbon atoms such as benzyl group, phenethyl group and the like; halogen-substituted alkyl groups having 1 to 12 carbon atoms such as 3-chloropropyl group, 3,3,3-trifluoropropyl group and the like. In certain embodiments, from the perspective of economy and heat resistance, there is a methyl group.

[0045] Component (A) can be produced by the hydrosilylation reaction of (A-1) an organopolysiloxane having at least two alkenyl groups per molecule and (A-2) an organosilicon compound having one hydrogen atom bonded to a silicon atom and at least one hydrolyzable (i.e., alkoxy) group bonded to a silicon atom.

[0046] Component (B) is an organopolysiloxane having an average of two (2) or more photoreactive groups per molecule. As such photoreactive groups, a mercapto group (-SH) functional group is most preferred. Examples of mercapto functional groups include mercaptoalkyl groups such as 3-mercaptopropyl group, 4-mercaptobutyl group, and 6-mercaptohexyl group. In addition, examples of groups bonded to the silicon atom in component (A) other than the mercapto functional group include: alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, etc.; aryl groups having 6 to 12 carbon atoms such as phenyl group, tolyl group, xylyl group, etc.; aralkyl groups having 7 to 12 carbon atoms such as benzyl group, phenethyl group, etc.; halogen-substituted alkyl groups having 1 to 12 carbon atoms such as 3-chloropropyl group, 3,3,3-trifluoropropyl group, etc. In certain embodiments, from the perspective of economy and heat resistance, there is a methyl group. In addition, the silicon atom in component (B) may be bonded to at least a small amount of hydrogen atoms, hydroxyl groups, or alkoxy groups such as methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group, etc.

[0047] In various embodiments, component (B) is an organopolysiloxane containing at least two siloxane units represented by the following general formula:

[0048] (HSR 1 )R 2 x SiO (3-x) / 2

[0049] In this formula, R 1 represents a divalent hydrocarbon group. Examples of divalent hydrocarbon groups include: alkylene groups having 1 to 8 carbon atoms such as methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, and octylene group. In certain embodiments, from the perspective of economy and heat resistance, there is a propenyl group.

[0050] In this formula, R 2 represents an alkyl group, an aryl group, a hydrogen atom, a hydroxyl group, or an alkoxy group. R 2Examples include: alkyl groups having 1 to 12 carbon atoms, such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, and the like; aryl groups having 6 to 12 carbon atoms, such as phenyl group, tolyl group, xylyl group, and the like; alkoxy groups having 1 to 6 carbon atoms, such as methoxy group, ethoxy group, propoxy group, and the like. In certain embodiments, from the perspective of economy and heat resistance, there is a methyl group.

[0051] In this formula, "x" is 0, 1, or 2. When "x" is 0, the siloxane unit is a T unit represented by the following general formula:

[0052] HSR 1 SiO 3 / 2 。

[0053] When "x" is 1, the siloxane unit is a D unit represented by the following general formula:

[0054] (HSR 1 )R 2 SiO 2 / 2 。

[0055] When "x" is 2, the siloxane unit is an M unit represented by the following general formula:

[0056] (HSR 1 )R 2 2SiO 1 / 2 。

[0057] Such component (B) may have mercapto (-SH) groups in the range of about 0.5 mass% to about 15.0 mass%, optionally about 0.5 mass% to about 10.0 mass%, optionally about 1.0 mass% to about 15.0 mass%, optionally about 1.0 mass% to about 10.0 mass%, optionally about 1.0 mass% to about 5.0 mass%, or optionally about 1.0 mass% to about 4.0 mass% of this component. This is because if the content is higher than the lower limit of this range, the curability of the obtained composition will be enhanced; however, on the other hand, if the content is lower than the upper limit of the above range, the heat resistance of the obtained cured product will be enhanced.

[0058] The average number of such photoreactive groups as mercapto (-SH) groups in component (B) is two (2) or more, and preferably two (2) to ten (10). Most preferably, component (B) has an average of three (3) to eight (8) mercapto (-SH) groups.

[0059] Component (C) is a condensation reaction catalyst to enhance the moisture curing of the composition. Examples of component (C) include organometallic catalysts (usually titaniumate-, tin- or zirconium-based catalysts), including titanium compounds such as tetrakis(isopropoxy)titanium, tetrakis(n-butoxy)titanium, tetrakis(tert-butoxy)titanium, bis(isopropoxy)bis(ethyl acetoacetate)titanium, bis(isopropoxy)bis(methyl acetoacetate)titanium, bis(isopropoxy)bis(acetylacetonate)titanium, etc.; zirconium compounds such as tetrakis(isopropoxy)zirconium, tetrakis(n-butoxy)zirconium, tetrakis(tert-butoxy)zirconium, bis(isopropoxy)bis(ethyl acetoacetate)zirconium, bis(isopropoxy)bis(methyl acetoacetate)zirconium, and bis(isopropoxy)bis(acetylacetonate)zirconium, etc.; tin compounds such as dimethyltin dinonanoate, dibutyltin dilaurate, dibutyltin dioctanoate, etc.; and stannous octoate, etc. The condensation catalyst is usually a titanate-, tin- or zirconium-based catalyst. Examples of suitable condensation catalysts include any one condensation catalyst or any combination of more than one condensation catalyst selected from the group consisting of: tetraisopropyl orthotitanate, titanium(IV) n-butoxide, titanium(IV) tert-butoxide, titanium(IV), bis(isopropoxy)bis(ethyl acetoacetate)titanium, tetrakis(trimethylsilyloxy)titanium; bis(isopropoxy)bis(methyl acetoacetate)titanium, zirconium(IV) isopropoxide, zirconium(IV) n-butoxide, zirconium(IV) tert-butoxide, bis(isopropoxy)bis(ethyl acetoacetate)zirconium, bis(isopropoxy)bis(methyl acetoacetate)zirconium, bis(isopropoxy)bis(acetylacetonate)zirconium, dimethyltin dinonanoate, dibutyltin dilaurate, dibutyltin dioctanoate, and stannous octoate.

[0060] The content of component (C) is an effective amount for moisture curing. In various embodiments, component (C) is present in an amount of about 0.01 parts by mass to about 10 parts by mass, optionally about 0.05 parts by mass to about 10 parts by mass, or optionally about 0.05 parts by mass to about 5 parts by mass, based on the total mass of components (A) to (F). This is because if the amount of component (C) is higher than the lower limit of this range, the obtained composition will be sufficiently cured by moisture; and if the amount of component (E) is lower than the upper limit of the above range, the surface curing rate of the obtained composition is improved.

[0061] Component (D) is one of the most typical features of the present invention and is a limited combination of the following photoinitiators (d1) to (d3):

[0062] (d1) 2,4,6-trimethylbenzoyl phenylphosphinate,

[0063] (d2) bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and

[0064] (d3) 2,2-dimethoxy-1,2-diphenylethan-1-one.

[0065] Component (D) is a limited combination of photoinitiators (d1) to (d3), which is used to enhance the photocuring reaction of the composition and also exhibits good to excellent curability and long-term storage (= pot life) stability throughout the composition at room temperature or ambient storage conditions. Also, this limited combination of photoinitiators is preferably easily and homogeneously soluble without using other organic solvents. Therefore, by using this limited combination of photoinitiators (d1) to (d3), a "solvent-free" doubly curable organopolysiloxane composition can be easily formulated. On the other hand, when any one of these components (d1) to (d3) is lacking in the composition, any one of the excellent curability, long-term storage (= pot life) stability, and good compatibility benefits in the solvent-free composition will be impaired.

[0066] In various embodiments, when the total mass of components (d1) to (d3) is 100% by mass, the mass ratios of components (d1) to (d3) are in the following ranges:

[0067] The mass ratio of component (d1) is in the range of 10% by mass to 30% by mass,

[0068] The mass ratio of component (d2) is in the range of 20% by mass to 40% by mass, and

[0069] The mass ratio of component (d3) is in the range of 40% by mass to 80% by mass.

[0070] The content of component (D) is an effective amount for photocuring. In various embodiments, component (D) is present in an amount of about 0.01 part by mass to about 5 parts by mass, optionally about 0.1 part by mass to about 5 parts by mass, or optionally about 0.1 part by mass to about 3 parts by mass per 100 parts based on the total mass of components (A) to (F). This is because if the amount of component (D) is higher than the lower limit of this range, the obtained composition will be sufficiently cured by UV light; however, on the other hand, if the amount of component (D) is lower than the upper limit of the above range, the mechanical properties of the obtained cured product will be enhanced.

[0071] In a preferred embodiment, the composition is substantially free of other photoinitiators except component (D). Specifically, the composition preferably does not contain other photoinitiators except component (D), and the amount of other photoinitiators except component (D) is 0.1 part by mass or more per 100 parts based on the total mass of components (A) to (F). The content of other photoinitiators except component (D) is preferably 0.01 part by mass or less per 100 parts based on the total mass of components (A) to (F), and most preferably below its detection limit.

[0072] Component (E) is a silane having an average of 2 or more hydrolyzable groups per molecule and is used as a crosslinking agent. It can also be used as a carrier liquid and / or a reactive diluent. Desirably, the hydrolyzable group is an alkoxy group, and more preferably the hydrolyzable group is an alkoxy group selected from the group consisting of methoxy, ethoxy, propoxy, and butoxy groups. Desirably, the silane can be a dialkoxysilane, a trialkoxysilane, or a combination of a dialkoxysilane and a trialkoxysilane. Most preferably, the silane is a trialkoxysilane.

[0073] The silane desirably has the following structure:

[0074] R 3 f Si(OR 3 ) 4-f

[0075] where the subscript f is one, two, or three (preferably one or two, most preferably one), and R 3 is independently selected from the group consisting of methyl group, ethyl group, propyl group, and butyl group at each occurrence. Examples of suitable silane compounds include any one or more combinations selected from methyltrimethoxysilane, ethyltriethoxysilane, and dimethyldimethoxysilane.

[0076] The content of component (E) is an effective amount for use as a crosslinking agent. In various embodiments, component (E) is present in an amount of about 0.01 parts by mass to about 10 parts by mass, optionally about 0.05 parts by mass to about 10 parts by mass, or optionally about 0.05 parts by mass to about 5 parts by mass, based on the total mass of components (A) to (F). This is because if the amount of component (E) is higher than the lower limit of this range, the resulting composition will have sufficient curing speed and curing properties.

[0077] Optionally, in order to enhance or improve the long-term stability of the composition, an epoxy-functional organosilicon compound can be formulated into the composition in combination with or at least partially replacing component (E). Examples of epoxy-functional organosilicon compounds include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 3,4-epoxybutyltrimethoxysilane, 3,4-epoxybutylmethyldimethoxysilane, 5,6-epoxyhexyltrimethoxysilane, 5,6-epoxyhexyltriethoxysilane, 8-glycidoxyoctyltrimethoxysilane, etc.; and epoxy-functional non-silicon compounds such as methyl glycidyl ether, glycidyl methacrylate, etc.

[0078] Optionally, as component (F), the composition further comprises a radical scavenger (inhibitor) to inhibit radical reactions during storage, thereby helping to increase the storage stability of the composition. Examples of suitable radical scavengers include any one of the following or any combination of more than one of the following: butylated hydroxytoluene (BHT), 4-methoxyphenol, and tert-butylhydroquinone, 6-tert-butyl-2,4-xylenol, 2-tert-butyl-1,4-benzoquinone, 4-tert-butylcatechol, 2,6-di-tert-butylphenol, and aluminum N-nitroso-N-phenylhydroxylamine salt.

[0079] The content of this component (F) is not limited, but it is generally present at a concentration of 0.001% by mass or higher, 0.01% by mass or higher, 0.05% by mass or higher, 0.50% by mass or higher, 1.0% by mass or higher based on the weight of the entire composition, and at the same time is generally present at a concentration of 2.0% by mass or lower, 1.5% by mass or lower, 1.0% by mass or lower based on the weight of the entire composition.

[0080] The composition may also contain one or more other additives, provided that they do not interfere with the curing mechanism. For example, conventional additives such as fillers, adhesion promoters, resins, pigments, moisture scavengers, fluorescent dyes, inhibitors, etc. may be included.

[0081] Fillers such as fumed silica or quartz are contemplated. The filler may be present in an amount of up to about 30% by weight, such as about 4% to about 20% by weight, of the total mass of components (A) to (F).

[0082] The inhibitor may be present in an amount of up to about 5% by weight, such as about 0.001% to about 1% by weight, of the total mass of components (A) to (F). A specific amount of the inhibitor should be balanced in a given composition to produce or improve the stability of the composition. Such amounts can be determined by routine experiments.

[0083] The adhesion promoter may be present in an amount of up to about 5% by weight, such as about 0.5% by weight, of the total mass of components (A) to (F).

[0084] [Solvent-free form] The composition is preferably of the "solvent-free" type. Preferably, the composition is substantially free of organic solvents, and the preferred content of the organic solvent is 1.0% by mass or lower of the entire composition, and most preferably below its detection limit. Examples of such organic solvents include, but are not limited to, toluene, xylene, alcohols, and liquid alkanes, as well as other low-viscosity or volatile silicone oils.

[0085] The composition can be prepared by mixing the corresponding components together to obtain a substantially homogeneous or homogeneously blended material and storing it in a container that is impervious to UV light and moisture. Generally, a single-packaging system is utilized, but if desired, a two-part packaging system can be used. Although the single-packaged product is ready for use upon dispersion, the two-part system typically requires mixing of the dispersed parts prior to use.

[0086] The composition can be used as described above for potting applications of various substrates (including electronic components and other heat-sensitive materials), as well as in coatings, encapsulants, and gels.

[0087] Available UV radiation sources include conventional mercury vapor lamps (which are designed to emit UV energy in various UV bands), LED curing lamps, and the like. For example, the available radiation wavelength range includes 200 nm to 400 nm.

[0088] UV curing is typically carried out in the range of 40 milliwatts per square centimeter (“mW / cm 2 (“mW / cm 2 ”) to about 300 mW / cm 2 such as in the range of about 70 mW / cm 2 to about 300 mW / cm 2 .

[0089] Examples

[0090] The dual-curing organopolysiloxane composition of the present invention will now be described in detail using working examples and comparative examples. Sample aging was carried out by storing the evaluation samples in an oven at 50 °C for two weeks to accelerate aging. UV curing was carried out by exposing samples with a thickness of 1 mm to 2 mm to a 5 J / cm 2 UV LED lamp (Phoseon FireJet TM FJ800) at 405 nm or 395 nm. For additional exposure to UV LED 365 nm, the samples were additionally exposed to 1 J / cm 2 to 3 J / cm 2 . The measurements were as follows.

[0091] <Measurement of UV curing depth>

[0092] The samples were filled into PE jigs with a diameter of 8 mm and a depth of 7 mm. After filling, the samples were exposed to a 10 J / cm 2 UV LED lamp at 405 nm or 395 nm. Then, after removing the samples from the jigs, the cured thickness was measured using a thickness gauge. The threshold for this property is 5 mm, i.e., >5 mm.

[0093] <Surface drying time (moisture curing rate)>

[0094] Place the sample in a UV - free area at 22 ± 2 °C and / 50% RH + / - 10%, and then smoothly touch the surface with a finger every 5 to 10 minutes. Then measure the time period during which nothing remains on the finger during the touch. The threshold for this property is 12 hours, i.e., < 12 hours.

[0095] <Shore A hardness test>

[0096] Once the sample is cured by UV exposure, it is stacked to a thickness of approximately > 8 mm, and then the Shore A hardness is measured using a Shore A hardness tester. After completion, this test sample is cured for 3 days under ambient conditions for moisture secondary curing, and then the Shore A hardness is measured in the same way. The threshold for the difference in Shore A hardness before and after 14 - day aging is 40%, i.e., < 40%.

[0097] <Viscosity measurement>

[0098] Measure the sample viscosity at 5 rpm and 23 ± 2 °C using a Brookfield HADVIII cone - plate viscometer with spindle CPA - 52Z. The threshold for the difference in viscosity before and after 14 - day aging is 30%, i.e., < 30%.

[0099] <Examples 1-5 and Comparative Examples 1-7>

[0100] Prepare the double - curing silicone composition shown in Table 1 using the following components (mass %).

[0101] Use the following organopolysiloxanes as component (A).

[0102] (a1): A vinyl - and alkoxysilyl - functional dimethylpolysiloxane having the following chemical structure:

[0103] CH2=CH(CH3O)2SiO(Si(CH2)2O) n Si(CH3O)2CH=CH2

[0104] (a2): A vinyl - and alkoxysilyl - functional dimethylpolysiloxane having the following chemical structure:

[0105] Si[O-(Si(CH3)2O) 30 -Si(CH3)2-CH=CH2]2[O-[Si(CH3)2O] 30 -Si(CH3)2-CH2CH2-

[0106] Si(CH3)2-O-Si(CH3)2-Si(OCH3)3]2

[0107] The following organopolysiloxanes are used as component (B).

[0108] (b1): Dimethylsiloxane methyl(3-mercaptopropyl)siloxane copolymer having the following chemical structure:

[0109] (R2R"SiO 1 / 2 )2(RR'SiO 2 / 2 ) m (R2SiO 2 / 2 ) n (wherein R = R" = methyl, R' = HS(CH2)2CH2-,

[0110] and the average n = 43 and m = 5)

[0111] The following condensation reaction catalysts are used as component (C).

[0112] (c1): Titanium acetylacetonate complex mixed with methyltrimethoxysilane

[0113] (c2): Titanium acetylacetonate complex

[0114] (c3): Tetra-n-butyl titanate

[0115] (c4): Tetra-tert-butyl titanate

[0116] The following photoinitiators are used as component (D).

[0117] (d1): 2,4,6-Trimethylbenzoyl phenylphosphinate

[0118] (d2): Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide

[0119] (d3): 2,2-Dimethoxy-1,2-diphenylethan-1-one

[0120] (d4): 2-Hydroxy-2-methylpropiophenone

[0121] (d5): 2,4,6-Trimethylbenzoyl diphenylphosphinate

[0122] The following silanes are used as component (E).

[0123] (e1): Methyltrimethoxysilane

[0124] (e2): Dimethyldimethoxysilane

[0125] (e3): Dimethyldiethoxysilane

[0126] The following radical scavengers are used as component (F).

[0127] (f1): Butylated hydroxytoluene

[0128] (f2): Aluminum N-nitroso-N-phenylhydroxylamine

[0129] The following is used as the component "filler": pyrogenic silica treated with hexamethyldisilazane.

[0130] The following is used as the component "adhesion promoter": the reaction of aminopropyltrimethoxysilane with glycidoxypropyltrimethoxysilane and methyltrimethoxysilane.

[0131] The following is used as the component "silicone resin": the reaction product of silicic acid, sodium salt, and chlorotrimethylsilane.

[0132] [Table 1]

[0133]

[0134] * A mixture of components (f1) and (f2) with a mass ratio of (f1) / (f2) = 83 / 17

[0135] [Table 2]

[0136]

[0137]

[0138] Industrial applicability

[0139] The dual-curable organopolysiloxane composition according to the present disclosure can be cured by both photocuring and by exposure to moisture, and exhibits good to excellent curability and long-term storage stability at room temperature or ambient storage conditions. In addition, the composition according to the present disclosure can be easily applied in the form of a "solvent-free" composition having excellent coating ability and appropriate viscosity. Therefore, the composition of the present invention can be used as a potting composition, a coating, an adhesive, and an encapsulant.

Claims

1. A dual-cure organopolysiloxane composition, comprising: (A) an organopolysiloxane having an average of one or more alkenyl groups per molecule and an average of one or more hydrolyzable groups per molecule; (B) an organopolysiloxane having an average of two (2) or more photoreactive groups per molecule; (C) a condensation reaction catalyst; (D) a combination of the following photoinitiators (d1) to (d3); (d1) 2,4,6-trimethylbenzoylphenylphosphinate, (d2) bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and (d3) 2,2-dimethoxy-1,2-diphenylethan-1-one, (E) a silane having an average of 2 or more hydrolyzable groups per molecule; and optionally, (F) Free radical scavengers.

2. The dual-cure organopolysiloxane composition according to claim 1, wherein when the total mass of components (d1) to (d3) is 100% by mass, the mass ratio of components (d1) to (d3) is within the following range: The mass ratio of the component (d1) is in the range of 10% by mass to 30% by mass, The mass ratio of the component (d2) is in the range of 20% by mass to 40% by mass, and The mass ratio of the component (d3) is within a range of 40% by mass to 80% by mass.

3. The dual-cure organopolysiloxane composition of claim 1, wherein the composition results from both a UV-radical cure mechanism and a moisture cure mechanism.

4. The dual-cure organopolysiloxane composition of claim 1, wherein the composition is substantially free of organic solvents.

5. The dual-cure organopolysiloxane composition according to claim 1, which is used as a potting composition, a coating, an adhesive, or an encapsulant.

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