Curable silicone composition, cured product and composite

Abstract

Provided is a curable silicone composition that can form a cured product having good adhesion strength to a substrate made of polyphenylene. The curable silicone composition of the present disclosure comprises (A) an organopolysiloxane having at least two alkenyl groups per molecule, (B) an organopolysiloxane having an average of two or more silicone atom-bonded hydrogen atoms per molecule and free of alkenyl groups, (C) an α-silane compound having a specific chemical structure, and (D) a curing catalyst.

Description

CURABLE SILICONE COMPOSITION, CURED PRODUCT AND COMPOSITECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and all advantages of U.S. Provisional Patent Application No. 63 / 666,943 filed on 02 July 2024, the content of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates to a curable silicone composition, a cured product thereof and a composite including the cured product.BACKGROUND

[0003] Curable silicone compositions are used in a wide range of industrial fields as they form cured products having excellent heat resistance, cold resistance, electrical insulation, weather resistance, water repellency, and transparency. Curable silicone compositions and their cured products are often used for adhering to substrates. For example, US2010 / 0256300A1 describes a self-adhesive addition-crosslinking silicone composition comprising an organosilicon compound, a platinum catalyst, and an a-silane with a specific structure.According to US2010 / 0256300A1 , the silicone composition is self-adhesive at room temperature and develops adhesion rapidly on un / non-pretreated substrates.SUMMARY

[0004] Polyphenylene sulfide (hereinafter, also abbreviated as “PPS”) is known for its excellent heat resistance, and it is widely used as a material for a substrate in various applications. However, it was difficult to achieve good adhesion between a substrate made of PPS (hereinafter, also abbreviated as “a PPS substrate”) and a cured product made from conventional curable silicone compositions including those described in US2010 / 0256300A1.

[0005] Accordingly, an object of the present disclosure is to provide a curable silicone composition that can form a cured product having good adhesion strength to a PPS substrate.

[0006] The curable silicone composition of the present disclosure comprises:(A) an organopolysiloxane having at least two alkenyl groups per molecule;(B) an organopolysiloxane having an average of two or more silicone atom-bonded hydrogen atoms per molecule and free of alkenyl groups;(C) an a-silane compound indicated by formula (I), shown below, CH2=CH-COO-CH2-Si(CH3)n(OR)3_n(I) where, in the formula (I), R is an optionally substituted alkyl group, and n is 0 or 1; and(D) a curing catalyst.

[0007] In some embodiments, the content of the (A) organopolysiloxane may be from 10.00 to 90.00 wt.%, based on the total weight of the curable silicone composition.

[0008] In some embodiments, the ratio of the number of moles of the silicone atom-bonded hydrogen atoms in the (B) organopolysiloxane per 1 mole of the alkenyl groups in the (A) organopolysiloxane may be from 0.30 to 5.00.

[0009] In some embodiments, the R may be a methyl group, and the n may be 0 in the formula (I)-

[0010] In some embodiments, the content of the (C) a-silane compound may be from 0.10 to 5.00 wt.%, based on the total weight of the curable silicone composition.

[0011] In some embodiments, the (D) curing catalyst may include at least one selected from the group consisting of a hydrosilylation catalyst and a condensation catalyst.

[0012] In some embodiments, the (D) curing catalyst may include a hydrosilylation catalyst selected from the group consisting of (methylcyclopentadienyl) trimethyl platinum (IV), (cyclopentadienyl) trimethyl platinum (IV), (1,2,3,4,5-pentamethyl cyclopentadienyl) trimethyl platinum (IV), (cyclopentadienyl) dimethylethyl platinum (IV), (cyclopentadienyl) dimethylacetyl platinum (IV), (trimethylsilyl cyclopentadienyl) trimethyl platinum (IV), (methoxycarbonyl cyclopentadienyl) trimethyl platinum (IV), (dimethylsilyl cyclopentadienyl) trimethylcyclopentadienyl platinum (IV), trimethyl (acetylacetonato) platinum (IV), trimethyl (3,5- heptanedionate) platinum (IV), trimethyl (methylacetoacetate) platinum (IV), bis(acetylacetonato) platinum (II), bis(2,4-pentanedionato) platinum (II), bis(2,4-hexanedionato) platinum (II), bis(2,4- heptanedionato) platinum (II), bis(3,5-heptanedionato) platinum (II), bis( 1 -phenyl- 1,3- butanedionato) platinum (II), bis(1,3-diphenyl-1,3-propanedionato) platinum (II), bis(hexafluoroacetylacetonato) platinum (II), and combinations thereof.

[0013] In some embodiments, the curable silicone composition of the present disclosure may further include (E) a siloxane compound having a silicon atom-bonded hydrogen atom and a trialkoxysilyl group.

[0014] The cured product of the present disclosure is obtainable from the curable silicone composition of the present disclosure.

[0015] The composite of the present disclosure comprises a substrate made of polyphenylene sulfide and the cured product of the present disclosure on the substrate.

[0016] According to the present disclosure, it is possible to provide a curable silicone composition that can form a cured product having good adhesion strength to a PPS substrate. According to the present disclosure, it is possible to provide a cured product having good adhesion strength to a PPS substrate. Moreover, according to the present disclosure, it is possible to provide a composite in which a cured product and a PPS substrate are well adhered to each other.DETAILED DESCRIPTION

[0017] Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percents are based on weight, all temperatures are in °C, and all test methods are current as of the filing date of this disclosure.

[0018] The term “composition,” as used herein, refers to a mixture of materials which comprises the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0019] The term “polymer,” as used herein, refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type.

[0020] The term “organopolysiloxane” as used herein, refers to a polymer containing multiple siloxane bonds and having at least one organic group. Organopolysiloxanes comprise siloxane units that are selected from those known in the art as: SiO^ (“Q” type), RxSiO3 / 2 (“T” type), RX2SiO2 / 2 (“D” type), and RX3SiO^ / 2 (“M” type). The subscript on the Rxgroup indicates how many R* groups are bound to the silicon atom. The subscript on the oxygen indicates how many oxygens are bound to the silicon that are also bound to another silicon (that is, how siloxane linkages, “Si-O-Si” bonds, the silicon atom participates in) divided by 2 because the oxygen is shared with another silicon atom so only half of each oxygen is considered bound to each silicon atom. Hence, a D-type unit comprises a silicon atom bound to two R* groups and sharing two oxygens with other silicon atoms, so it includes two half oxygen atoms. In general, the R* group can be any substituent other than -OSi (that is, a siloxane bond to the silicon). Generally, the R* group is a hydrogen or hydrocarbyl bound to the silicon atom through a carbon-silicon bond. However, the Rxgroup in the broadest scope herein can also be a group bound to the silicon atom with an atom other than hydrogen or carbon, for instance sulfur or oxygen. For instance, the R* group can be selected from hydroxyl or alkoxyl groups, which are jointly referred to as OZ groups.

[0021] The term “silicone composition,” as used herein, refers to a composition including an organopolysiloxane.

[0022] The terms “comprising,” “including,” “having,” and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term “comprising” may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, “consisting essentially of’ excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term “consisting of’ excludes anycomponent, step or procedure not specifically delineated or listed.

[0023] The term “optionally substituted”, unless otherwise specified, means that a group may be unsubstituted or substituted by one or more (e.g., 1 , 2, 3, 4 or 5) of the substituents which may be same or different.

[0024] The term “a substrate made of polyphenylene sulfide” are not intended to exclude a substrate containing components other than polyphenylene sulfide. In some embodiments, the content of polyphenylene sulfide in the PPS substrate may be 50.00 wt.% or more, or optionally 55.00 wt.% or more, based on the total weight of the PPS substrate. At the same time the content of polyphenylene sulfide in the PPS substrate may be 100.00 wt.% or less, optionally 90.00 wt.% or less, or optionally 80.00 wt.% or less, based on the total weight of the PPS substrate. Non limiting examples of components other than polyphenylene sulfide in the PPS substrate include glass fibers, carbon fibers, and combinations thereof.

[0025] The use of “for example,” “e.g.,” and “such as,” to list illustrative examples does not limit to only the listed examples. 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.

[0026] <Curable silicone composition>

[0027] The present disclosure provides a curable silicone composition. The silicone composition can be cured, and a cured product obtainable by curing the silicone composition has good adhesion strength to a PPS substrate, as described below.

[0028] The silicone composition comprises (A) an organopolysiloxane, (B) an organopolysiloxane, (C) an a-silane compound, and (D) a curing catalyst. The silicone composition optionally comprises components other than components (A) to (D) (hereinafter, abbreviated as “Optional components”).

[0029] (A) Organopolysiloxane

[0030] The silicone composition comprises (A) an organopolysiloxane. The (A) organopolysiloxane is one of base compounds of the silicone composition and has at least two alkenyl groups per molecule. The alkenyl groups can react with other functional groups (for example, Si-H groups in the (B) organopolysiloxane) through a curing reaction initiated by the (D) curing catalyst. Note that the (A) organopolysiloxane may comprise two or more different organopolysiloxanes, which may be independently selected.

[0031] Non-limiting examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a heptenyl group, a hexenyl group, and combinations thereof. Of these alkenyl groups, a vinyl group is preferable in terms of further increasing adhesion strength of the cured product to a PPS substrate.

[0032] The number of the alkenyl groups per molecule in the (A) organopolysiloxane is 2 or more as stated above. At the same time the number of the alkenyl groups per molecule in the (A)organopolysiloxane may be 100 or less, optionally 50 or less, optionally 10 or less, optionally 5 or less, or optionally 3 or less. Preferably, the number of the alkenyl groups per molecule in the (A) organopolysiloxane may be from 2 to 100, optionally from 2 to 50, optionally from 2 to 10, optionally from 2 to 5, optionally from 2 to 3, or optionally 2.

[0033] In the (A) organopolysiloxane, the alkenyl group may be bonded directly to the silicon atom, or the alkenyl group may be bonded to the silicon atom via another group.

[0034] In some embodiments, the (A) organopolysiloxane may have a silicon-bonded group which does not include an alkenyl group. Non-limiting examples of the silicon-bonded group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl groups, a cyclohexyl group, a heptyl group, an octyl group, a nonyl group, a decyl groups, an undecyl groups, a dodecyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and these groups in which a part or all of the hydrogen atoms is substituted with a halogen atom such as a fluorine atom, a chloride atom, and a bromine atom, or is substituted with nitrogen containing groups such as a cyano or a tertiary amine group. Note that the (A) organopolysiloxane may have two or more different silicon-bonded groups which do not include alkenyl group, which may be independently selected.

[0035] The (A) organopolysiloxane may be linear, branched, partly branched, cyclic, resinous (i.e., have a three-dimensional network), or may comprise a combination of different structures. For example, the (A) organopolysiloxane may comprise any combination of M, D, T and / or Q siloxane units, so long as the (A) organopolysiloxane includes at least two alkenyl groups per molecule. These siloxane units can be combined in various manners to form cyclic, linear, branched and / or resinous structures.

[0036] In some embodiments, the (A) organopolysiloxane may be a linear organopolysiloxane having alkenyl groups at the two terminals. For example, the linear organopolysiloxane may be represented by formula (II):RaRb2SiO-(Rb2SiO)m-SiRaRb2(II)

[0037] Each Rais directly bonded to the silicon atom and may be same or different. Each Rais individually selected from alkenyl groups, preferably selected from the group consisting of a vinyl group, an allyl group, a butenyl group, a pentenyl group, a heptenyl group, a hexenyl group, and more preferably a vinyl group. Ramay be unsubstituted or substituted with one or more groups that do not interfere with curing of the silicone composition.

[0038] Each Rbis directly bonded to the silicon atom and may be same or different. Each Rbis individually selected from the group consisting of aryl groups and alkyl groups, preferably selected from the group consisting of aryl groups having from six to twelve carbon atoms andalkyl groups having from one to ten carbon atoms, more preferably selected from the group consisting of alkyl groups having from one to ten carbon atoms, and even more preferably a methyl group. R& may be unsubstituted or substituted with one or more groups that do not interfere with curing of the silicone composition. In some embodiments, each R& may not contain an alkenyl group.

[0039] Subscript “m” refers to an average number of (R^SiO) units per molecule in the organopolysiloxane of the above formula (II). Subscript “m” is not particularly limited but may be 50 or more, optionally 100 or more, optionally 300 or more, or optionally 500 or more. At the same time subscript “m” may be 4,000 or less, optionally 3,000 or less, optionally 2,000 or less, or optionally 1 ,000 or less. Preferably subscript “m” may be from 50 to 4,000, optionally from 100 to 3,000, optionally from 300 to 2,000, or optionally from 500 to 1 ,000.

[0040] In some embodiments, the content of the (A) organopolysiloxane in the silicone composition may be 10.00 wt.% or more, optionally 50.00 wt.% or more, optionally 60.00 wt.% or more, optionally 70.00 wt.% or more, or optionally 75.00 wt.% or more, based on the total weight of the silicone composition. At the same time the content of the (A) organopolysiloxane in the silicone composition may be 90.00 wt.% or less, optionally 87.00 wt.% or less, optionally 84.00 wt.% or less, optionally 82.00 wt.% or less, or optionally 80.00 wt.% or less, based on the total weight of the silicone composition. Preferably, the content of the (A) organopolysiloxane in the silicone composition may be from 10.00 to 90.00 wt.%, optionally from 50.00 to 87.00 wt.%, optionally from 60.00 to 84.00 wt.%, optionally from 70.00 to 82.00 wt.%, or optionally from 75.00 to 80.00 wt.%, based on the total weight of the silicone composition.

[0041] (B) Organopolysiloxane

[0042] The silicone composition comprises (B) an organopolysiloxane. The (B) organopolysiloxane has an average of two or more silicon atom-bonded hydrogen atoms per molecule and free of alkenyl groups. The silicon atom-bonded hydrogen atoms can react with the alkenyl groups of, for example, the (A) organopolysiloxane though a curing reaction initiated by the (D) curing catalyst and a crosslinked structure including (A) and (B) can be formed. In other words, the (B) organopolysiloxane acts as a cross-linker in the silicone composition. Note that the (B) organopolysiloxane may comprise two or more different organopolysiloxanes, which may be independently selected.

[0043] The average number of the silicon atom-bonded hydrogen atoms per molecule in the (B) organopolysiloxane is 2 or more as stated above, optionally may be 3 or more, optionally 4 or more, optionally 5 or more, or optionally 7 or more. At the same time the average number of the silicon atom-bonded hydrogen atoms in the (B) organopolysiloxane may be 800 or less, optionally 500 or less, optionally 200 or less, optionally 100 or less, or optionally 80 or less. Preferably, the average number of the silicon atom-bonded hydrogen atoms in the (B)organopolysiloxane may be from 2 to 800, optionally from 3 to 500, optionally from 4 to 200, optionally from 5 to 100, or optionally from 7 to 80. When the average number of the silicon atom- bonded hydrogen atoms per molecule in the (B) organopolysiloxane is within any of the ranges set forth above, a crosslinked structure including (A) and (B) is well formed and adhesion strength of the cured product to a PPS substrate can be further increased. The average number of the silicon atom-bonded hydrogen atoms in the (B) organopolysiloxane referred in the present disclosure can be measured by an infrared spectrometer or a nuclear magnetic resonance spectrometer.

[0044] The (B) organopolysiloxane may be linear, branched, partly branched, cyclic, resinous (i.e., have a three-dimensional network), or may comprise a combination of different structures. For example, the (B) organopolysiloxane may comprise any combination of M, D, T and / or Q siloxane units, so long as the (B) organopolysiloxane includes an average of two or more silicone atom-bonded hydrogen atoms per molecule and free of alkenyl groups. These siloxane units can be combined in various manners to form cyclic, linear, branched and / or resinous structures.

[0045] In some embodiments, the (B) organopolysiloxane may be a branched organopolysiloxane in terms of further increasing adhesion strength of the cured product to a PPS substrate. For example, the branched organopolysiloxane may be represented by the average unit formula (III):(RA3SiO1 / 2)q(RA2SiO2 / 2)r(RASiO3 / 2)s(SiO4 / 2)t(RBO1 / 2)u(HI)

[0046] Each RAmay be same or different and is individually selected from the group consisting of hydrogen atom and monovalent hydrocarbon groups free of alkenyl groups, with the proviso that the average number of the silicon atom-bonded hydrogen atoms per molecule in the organopolysiloxane of formula (III) is two or more. The monovalent hydrocarbon group for RAmay be a hydrocarbon groups having 1 to 10 carbon atoms and being free of alkenyl groups, preferably a methyl group or a phenyl group, and more preferably a methyl group.

[0047] R® is selected from the group consisting of hydrogen atom and alkyl groups having 1 to 10 carbon atoms, preferably hydrogen atom, a methyl group and an ethyl group.

[0048] Subscript “q”, “r”, “s”, “t”, and “u” are numbers satisfying the following: 0.01 S q < 0.80, 0.00 S r < 0.98, 0.00 £ s ^ 0.80, 0.00 S t S 0.80, 0.00 £ u 0.05, where (s + 1) S 0.01 and (q + r + s + t) = 1.00.

[0049] In some embodiments, in terms of further increasing adhesion strength of the cured product to a PPS substrate, the (B) organopolysiloxane may be an MQ resin represented by the average unit formula(H(CH3)2Siv)

[0050] Subscript “p1”, “p2”, and “p3” are numbers satisfying the following: 0.01 S p1 S 0.65, 0.00 S p2 S 0.50, 0.20 < p3 < 0.80, where (p1 + p2 + p3) = 1.00.

[0051] In some embodiments, the ratio of the number of moles of the silicone atom-bonded hydrogen atoms in the (B) organopolysiloxane per 1 mole of the alkenyl groups in the (A) organopolysiloxane (hereinafter, also abbreviated as “Si-H / Vi molar ratio”) in the silicone composition may be 0.30 or more, optionally 0.50 or more, optionally 0.70 or more, or optionally 0.90 or more. At the same time the Si-H / Vi molar ratio in the silicone composition may be 5.00 or less, optionally 4.00 or less, optionally 3.00 or less, optionally 2.50 or less, or optionally 2.00 or less. Preferably, the Si-H / Vi molar ratio in the silicone composition may be from 0.30 to 5.00, optionally from 0.30 to 4.00, optionally from 0.50 to 3.00, optionally from 0.50 to 2.50, optionally from 0.70 to 2.00, or optionally from 0.90 to 2.00. When the Si-H / Vi molar ratio in the silicone composition is within any of the ranges set forth above, adhesion strength of the cured product to a PPS substrate can be further increased.

[0052] In some embodiments, the content of the (B) organopolysiloxane in the silicone composition may be 0.50 wt.% or more, optionally 1 .00 wt.% or more, optionally 1 .50 wt.% or more, or optionally 2.00 wt.% or more, based on the total weight of the silicone composition. At the same time the content of the (B) organopolysiloxane in the silicone composition may be 15.00 wt.% or less, optionally 10.00 wt.% or less, optionally 7.00 wt.% or less, or optionally 4.00 wt.% or less, based on the total weight of the silicone composition. Preferably, the content of the (B) organopolysiloxane in the silicone composition may be from 0.50 to 15.00 wt.%, optionally from 1.00 to 10.00 wt.%, optionally from 1.50 to 7.00 wt.%, or optionally from 2.00 to 4.00 wt.%. When the content of the (B) organopolysiloxane in the silicone composition is within any of the ranges set forth above, adhesion strength of the cured product to a PPS substrate can be further increased.

[0053] (C) a -si lane compound

[0054] The silicone composition comprises (C) an a-silane compound. The (C) a-silane compound acts as an adhesion promoter in the silicone composition and can increase adhesion strength of the cured product to a PPS substrate. The (C) a-silane compound is represented by formula (I):CH2=CH-COO-CH2-Si(CH3)n(OR)3.n(I)

[0055] Each R may be same or different and is individually selected from optionally substituted alkyl groups, preferably selected from alkyl groups having 1 to 6 carbon atoms, more preferably a methyl group in terms of further increasing adhesion strength of the cured product to a PPS substrate.

[0056] Subscript “n” refers to the number of methyl groups directly bonded to the silicon atom per molecule. Subscript “n” is 0 or 1 , preferably 0 in terms of further increasing adhesion strengthof the cured product to a PPS substrate.

[0057] Note that although it is not clear why the (C) a-silane compound can increase adhesion strength of the cured product to a PPS substrate, it is presumed that the acryloyl group (CH2=CH- C(=O)-)) having strong reactivity can be firmly adhered to a PPS substrate that is generally difficult to adhere.

[0058] Note that the (C) a-silane compound may comprise two or more different compounds, which may be independently selected.

[0059] In some embodiments, the content of the (C) a-silane compound in the silicone composition may be 0.10 wt.% or more, optionally 0.60 wt.% or more, optionally 1.00 wt.% or more, or optionally 1 .40 wt.% or more, based on the total weight of the silicone composition. At the same time the content of the (C) a-silane compound in the silicone composition may be 5.00 wt.% or less, optionally 4.00 wt.% or less, optionally 3.00 wt.% or less, or optionally 2.50 wt.% or less, based on the total weight of the silicone composition. Preferably, the content of the (C) a- silane compound in the silicone composition may be from 0.10 to 5.00 wt.%, optionally from 0.60 to 4.00 wt.%, optionally from 1.00 to 3.00 wt.%, or optionally from 1.40 to 2.50 wt.%. When the content of the (C) a-silane compound in the silicone composition is within any of the ranges set forth above, adhesion strength of the cured product to a PPS substrate can be further increased.

[0060] (D) Curing catalyst

[0061] The type of the (D) curing catalyst is not specifically limited as long as it can cure the silicone composition through a curing reaction, the (D) curing catalyst may comprise two or more different compound, which may be independently selected. Non-limiting examples of the curing reaction include hydrosilylation reaction, condensation reaction, and combinations thereof. The curing catalyst used in the hydrosilylation reaction (hereinafter referred to as “hydrosilylation catalyst”) and the curing catalyst used in the condensation reaction (hereinafter referred to as “condensation catalyst”) will be described in detail.

[0062] Hydrosilylation catalysts can promote the hydrosilylation reaction between an alkenyl group and a silicon-bonded hydrogen atom and cure the silicone composition. In some embodiments, the hydrosilylation catalyst comprises a platinum group metal. The platinum group metal may be selected from the group consisting of platinum, rhodium, ruthenium, palladium, osmium, and iridium. Alternatively, the platinum group metal may be platinum. In some embodiments, the hydrosilylation catalyst may be (i) a radiation activatable catalyst, i.e., capable of catalyzing hydrosilylation reaction after irradiation (exposure to actinic radiation, e.g., exposure to visible or UV light), (ii) a hydrosilylation catalyst activatable by means other than irradiation, e.g., capable of catalyzing hydrosilylation reaction without irradiation, such as by heating, or (iii) a combination of both (i) and (ii). The hydrosilylation catalyst used as the (D) curing catalyst preferably includes the (i) radiation activatable catalyst.

[0063] Non-limiting examples of the (i) radiation activatable catalysts include (methylcyclopentadienyl) trimethyl platinum (IV), (cyclopentadienyl) trimethyl platinum (IV), (1 ,2,3,4,5-pentamethyl cyclopentadienyl) trimethyl platinum (IV), (cyclopentadienyl) dimethylethyl platinum (IV), (cyclopentadienyl) dimethylacetyl platinum (IV), (trimethylsilyl cyclopentadienyl) trimethyl platinum (IV), (methoxycarbonyl cyclopentadienyl) trimethyl platinum (IV), (dimethylsilyl cyclopentadienyl) trimethylcyclopentadienyl platinum (IV), trimethyl (acetylacetonato) platinum (IV), trimethyl (3,5-heptanedionate) platinum (IV), trimethyl (methylacetoacetate) platinum (IV), bis(acetylacetonato) platinum (II), bis(2,4-pentanedionato) platinum (II), bis(2,4-hexanedionato) platinum (II), bis(2,4-heptanedionato) platinum (II), bis(3,5-heptanedionato) platinum (II), bis(1- phenyl-1 ,3-butanedionato) platinum (II), bis(1,3-diphenyl-1 ,3-propanedionato) platinum (II), bis(hexafluoroacetylacetonato) platinum (II), and combinations thereof. Among them, (methylcyclopentadienyl) trimethyl platinum (IV) and bis(acetylacetonato) platinum (II) are preferable.

[0064] In some embodiments, the content of the hydrosilylation catalyst in the silicone composition may be 1.0x10'5 wt.% or more, or optionally 1.0x10'4 wt.% or more, based on the total weight of the silicone composition. At the same time the content of the hydrosilylation catalyst in the silicone composition in the silicone composition may be 1.0x10'2 wt.% or less, or optionally 5.0x10'5 wt.% or less, based on the total weight of the silicone composition. Preferably, the hydrosilylation catalyst in the silicone composition may be from 1.0x10'5 to 1.0x10'2 wt.%, or optionally from 1.0x10'4 wt.% to 5.0x10'5 wt.%, based on the total weight of the silicone composition.

[0065] Condensation catalysts can promote the dealcoholization condensation reaction between alkoxysilyl groups and cure the silicone composition. In some embodiments, the condensation catalyst may be a titanate, tin, zinc, aluminum, or zirconium based catalyst. Nonlimiting examples of the condensation catalysts include titanium tetrakis(2-methylpropan-2-olate), tetraisopropylorthotitanate, titanium (IV) n-butoxide, titanium tetrakis(2-methylpropan-2-olate) (also known as titanium (IV) t-butoxide), titanium (IV), titanium di(isopropoxy)bis(ethylacetoacetate), Tetrakis(trimethylsiloxy)titanium; titanium di(isopropoxy)bis(methylacetoacetate), zirconium (IV) isopropoxide, zirconium (IV) n-butoxide, zirconium (IV) t-butoxide, zirconium di(isopropoxy)bis(ethylacetoacetate), zirconium di(isopropoxy)bis(methylacetoacetate), zirconium di(isopropoxy)bis(acetylacetonate, dimethyltin dineodecanoate, dibutyltin dilaurate, dibutyltin dioctoates, stannous octoate, and combinations thereof. Among them, titanium tetrakis(2-methylpropan-2-olate) are preferable.

[0066] In some embodiments, the content of the condensation catalyst in the silicone composition may be 0.05 wt.% or more, or optionally 0.10 wt.% or more, based on the total weightof the silicone composition. At the same time the content of the condensation catalyst in the silicone composition in the silicone composition may be 2.00 wt.% or less, optionally 0.80 wt.% or less, or optionally 0.40 wt.% or less, based on the total weight of the silicone composition. Preferably, the content of the condensation catalyst in the silicone composition may be from 0.05 to 2.00 wt.%, optionally from 0.05 to 0.80 wt.%, or optionally from 0.10 to 0.40 wt.%, based on the total weight of the silicone composition.

[0067] Optional components

[0068] Optional components are not specifically limited. Non-limiting examples of the optional components include (E) a siloxane compound having a silicon atom-bonded hydrogen atom and a trialkoxysilyl group, (F) a filler, (G) a vinylic cross-linker having at least three vinyl groups other than the (A) organopolysiloxane, and (H) an adhesion promoter other than the (C) a-silane compound.

[0069] Note that one of these optional components may be used individually, or two or more of these optional components may be used in combination.

[0070] The (E) siloxane compound has a silicone atom-bonded hydrogen atom. The silicone atom-bonded hydrogen atom can react with, for example, the alkenyl group of the (A) organopolysiloxane through a curing reaction by hydrosilylation. Also, since the (E) siloxane compound has a trialkoxysilyl group with high reactivity, the (E) siloxane compound can further increase adhesion strength of the cured product to a PPS substrate.

[0071] In some embodiments, the (E) siloxane compound may be represented by the following formula:

[0072] Each R^ may be same or different and is individually selected from monovalent hydrocarbon groups free of aliphatic unsaturation, preferably selected from the group consisting of alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, octadecyl, cyclopentyl, and cyclohexyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenethyl, and phenylpropyl; and halogenated alkyl groups such as 3-chloropropyl and 3,3,3-trifluoropropyl, and more preferably selected from the group consisting of a methyl group and a phenyl group.

[0073] Each R^ may be same or different and is individually selected from alkyl groups, preferably selected from the group consisting of a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group, and more preferably selected from the group ofa methyl group and an ethyl group.

[0074] is selected from alkylene groups, preferably selected from alkylene groups having from two to ten carbon atoms, and more preferably selected from the group consisting of a methylene group and a propylene group.

[0075] Subscript “p” refers to a number of (R^ 2SIO) unit and an integer from 1 to 50, preferably an integer from 1 to 10, and more preferably an integer from 1 to 5.

[0076] In some embodiments, the content of the (E) siloxane compound in the silicone composition may be 0.10 wt.% or more, optionally 0.20 wt.% or more, or optionally 0.40 wt.% or more, based on the total weight of the silicone composition. At the same time the content of the (E) siloxane compound in the silicone composition in the silicone composition may be 2.00 wt.% or less, optionally 1 .50 wt.% or less, or optionally 1.00 wt.% or less, based on the total weight of the silicone composition. Preferably, the content of the (E) siloxane compound in the silicone composition may be from 0.10 to 2.00 wt.%, optionally from 0.20 to 1.50 wt.%, or optionally from 0.40 to 1.00 wt.%, based on the total weight of the silicone composition. When the content of the (E) siloxane compound in the silicone composition is within any of the ranges set forth above, adhesion strength of the cured product to a PPS substrate can be further increased.

[0077] The (F) filler is not specifically limited and can be selected depending on the intended use of the silicone composition. Non-limiting examples of the (F) filler include fumed silica, silica aerogel, silica xerogel, precipitated silica, pyrogenic silica, diatomaceous silica, ground quartz, crushed quartz, aluminum silicates, mixed aluminum and magnesium silicates, zirconium silicate, mica powder, calcium carbonate such as precipitated calcium carbonate or ground calcium carbonate, glass powder and fibers, titanium oxides of the pyrogenic oxide and rutile type, barium zirconate, barium sulphate, barium metaborate, boron nitride, lithopone, the oxides of iron, zinc, chrome, zirconium, and magnesium, the different forms of alumina (hydrated or anhydrous), graphite, talc, diatomaceous earth, chalk sand, carbon black, and clays such as calcined clay and organic materials such as the phthalocyanines, cork powder, sawdust, synthetic fibers and synthetic polymers (polytetrafluoroethylene, polyethylene, polypropylene, polystyrene and polyvinyl chloride), and combinations thereof.

[0078] In some embodiments, the content of the (F) filler in the silicone composition may be 1.00 wt.% or more, optionally 5.00 wt.% or more, or optionally 10.00 wt.% or more, based on the total weight of the silicone composition. At the same time the content of the (F) filler in the silicone composition may be 40.00 wt.% or less, optionally 30.00 wt.% or less, or optionally 20.00 wt.% or less, based on the total weight of the silicone composition. Preferably, the content of the (F) filler in the silicone composition may be from 1.00 to 40.00 wt.%, optionally from 5.00 to 30.00 wt.%, or optionally from 10.00 to 20.00 wt.%, based on the total weight of the silicone composition.

[0079] The (G) vinylic cross-linker has at least three vinyl groups per molecule. The vinyl groups can react with the silicon atom-bonded hydrogen of the (B) organopolysiloxane through a curing reaction by hydrosilylation, and a three-dimensional high-density cross-linked structure is formed by the (G) vinyl crosslinker.

[0080] In some embodiments, the (G) vinylic cross-linker may be selected from a silicone containing compound having at least three vinyl groups. Non-limiting examples of the (G) vinylic cross-linker include tetra(dimethylvinylsiloxy)silane, tris(vinyldimethylsiloxy)methylsilane, 2,4,6,8-Tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, and combinations thereof.

[0081] In some embodiments, the content of the (G) vinylic cross-linker in the silicone composition may be 0.10 wt.% or more, or optionally 0.50 wt.% or more, based on the total weight of the silicone composition. At the same time the content of the (G) vinylic cross-linker in the silicone composition may be 5.00 wt.% or less, or optionally 3.00 wt.% or less, based on the total weight of the silicone composition. Preferably, the content of the (G) vinylic cross-linker in the silicone composition may be from 0.10 to 5.00 wt.%, or optionally from 0.50 to 3.00 wt.%, based on the total weight of the silicone composition. When the content of the (G) vinylic cross-linker in the silicone composition is within any of the ranges set forth above, adhesion strength of the cured product to a PPS substrate can be further increased.

[0082] The (H) adhesion promoter other than the (C) a-silane compound is not specifically limited. Non-limiting examples of the (H) adhesion promoter include 1,6- bis(trimethoxysilyl)hexane, 3-(glycidoxypropyl)trimethoxysilane, methacryloxymethyltrimethoxysilane, and combinations thereof. Among them, 1,6- bis(trimethoxysilyl)hexane is preferable in terms of further increasing adhesion strength of the cured product to a PPS substrate.

[0083] In some embodiments, the content of the (H) adhesion promoter in the silicone composition may be 0.001 wt.% or more, or optionally 0.01 wt.% or more, based on the total weight of the silicone composition. At the same time the content of the (H) adhesion promoter in the silicone composition may be 5.00 wt.% or less, optionally 4.00 wt.% or less, optionally 3.00 wt.% or less, optionally 2.00 wt.% or less, optionally 0.50 wt.% or less, or optionally 0.30 wt.% or less, based on the total weight of the silicone composition. Preferably, the content of the (H) adhesion promoter in the silicone composition may be from 0.001 to 5.00 wt.%, optionally from 0.001 to 4.00 wt.%, optionally from 0.001 to 3.00 wt.%, optionally from 0.001 to 2.00 wt.%, optionally from 0.001 to 0.50 wt.%, or optionally from 0.01 to 0.30 wt.%, based on the total weight of the silicone composition. When the content of the (H) adhesion promoter in the silicone composition is within any of the ranges set forth above, adhesion strength of the cured product to a PPS substrate can be further increased.

[0084] Method of preparing the silicone composition

[0085] The method of preparing the silicone composition is not specifically limited. The silicone composition is obtainable by mixing the above-described respective components in a known manner.

[0086] <Cured product>

[0087] The cured product of the present disclose is obtainable by curing the above silicone composition described above. In some embodiments, the cured product may be obtainable by curing the silicone composition through hydrosilylation reaction and / or condensation reaction, preferably through both hydrosilylation reaction and condensation reaction. The conditions for curing the silicone composition are not specifically limited and can be chosen depending on factors such as the type of each components described above. As stated above, the cure product of the silicone composition has good adhesion strength to a PPS substrate.

[0088] <Composite>

[0089] The composite of the present disclosure comprises: a substrate made of polyphenylene sulfide; and the cured product described above. In some embodiments, the composite may be produced by curing the silicone composition on a PPS substrate. In some embodiments, the composite may have a structure in which the cured product is sandwiched between a first substrate and a second substrate and at least one of the two substrate is a PPS substrate. For example, the composite having the above structure may be produced through the method comprising the following i) to iv): i) applying the silicone composition on a first substrate; ii) irradiating the silicone composition on the first substrate with UV light for activating a hydrosilylation catalyst; iii) bonding the silicone composition on the first substrate to the second substrate to obtain a laminate; and iv) curing the silicone composition in the laminate over a specified period (for example, 24 hours to a few days) to obtain a composite in which the first substrate, a cured product, and the second substrate are laminated in this order.

[0090] As stated above, the cured product and the PPS substrate are well adhered to each other in the composite of the present disclosure.

[0091] The use of the silicone composition, the cured product and the composite are not specifically limited. Non-limiting examples for the use include adhesives, potting materials, coating materials, encapsulants and sealing materials in electric / electronic equipment, such as circuit boards, solar cell modules, and optical fibers.EXAMPLES

[0092] The silicone composition, the cured product and the composite of the present disclosure will now be described in detail using Inventive Examples and Comparative Examples. Note that, in the formulas, “Me” indicates methyl group. The adhesion strength to PPS of the cured product was measured as follows.

[0093] <Adhesion strength to PPS>

[0094] 250 mg of the silicone composition as an adhesive sample was dispensed onto each primed die and subsequently was irradiated using latent cure at 2,000 mJ / cm for hydrosilylation reaction (a UV cure). There was 10 to 30 min. pot life after the UV irradiation depending on the adhesion promoter used. Immediate assembly was done by placing a PPS substrate directly onto the adhesive sample with a bond line thickness of 0.5 mm. After that, a moisture cure by condensation reaction was done for three days under conditions of 50% relative humidity and 21 °C. The die shear test for measuring a mean measure force (N) on PPS as adhesion strength to PPS of the cured product was performed as follows.

[0095] The die shear tester used is equipped with a 4 stack BenchCel Microplate Handler, a Keyence Barcode reader, a XYZTec Sigma Condor Bond Tester, and a Keyence CV-X visioning system. The PPS substrate was moved from the jigs to microplate frames and then loaded into a BenchCel stack. A test method was then chosen, and the dies were sheared off at a rate of 1 ,500pm / min. using a custom offset anvil and a max force (N) and force / displacement curve were recorded. After all the dies were sheared, the BenchCel then transferred the PPS substrate and frame to the Keyence visioning system. Subsequently, an image was taken and used to analyze the adhesive failure mechanism. After imaging, the substrate and frame were then up stacked to a dispense stacker and the process was repeated for the remainder of the prepared parts. The average value of the multiple max force (N) values obtained was defined as mean measure force (N). The higher the mean measure force (N) is, the stronger the adhesion strength to PPS is.

[0096] The components used in the Inventive Examples and Comparative Examples are listed in the Table 1 below.

[0097] Table 1

[0098] (A1) organopolysiloxane, (G1) vinylic cross-linker and the premix of the (F1) filler were obtained from Dow Silicones Corporation.

[0099] (B1) organopolysiloxane was prepared according to the teaching of US4774310.

[0100] (C1) a-silane compound, silane-2, silane-3, and silane-4 are commercially available from Gelest.

[0101] (D1) hydrosilylation catalyst is commercially available from Sigma Aldrich.

[0102] (D2) condensation catalyst is commercially available from Dorf Ketal.

[0103] (E1) silane-1 is commercially available from Macklin Biochemical Company.

[0104] clnventive Example 1>

[0105] Step 1 : Preparation of a masterbatch

[0106] 1300 g of the premix of the (F1) filler (including 910 g of the (A1) organopolysiloxane and 390 g of the (F1) filler), 1100 g of the (A1 ) organopolysiloxane, 26 g of the (G1) vinylic crosslinker, 54.6 g of the (B1) organopolysiloxane, and 15.6 g of the (E1) silane-1 were mixed in a Hobart mixer for 20 minutes at room temperature to obtain a mixture. After scraping, the mixture was further mixed in the mixer to obtain a masterbatch. The obtained masterbatch includes the components described in the following Table 2.

[0107] Table 2

[0108] Step 2: Preparation of a silicone composition

[0109] 96.15 parts by weight of the masterbatch obtained above, 1 .80 parts by weight of the (C1) a-silane compound were added to 30cc UV stable Adhesive Syringe Barrel Sleeve and mixed using FlackTek SpeedMixer^ (dual axis) at 3,500 rpm for 3 minutes to obtain a mixture. Subsequently, 0.05 parts by weight of a catalyst premix (including 2 wt.% of (D1) hydrosilylation catalyst and 98 wt.% of the silane-2) and 0.20 parts by weight of the (D2) condensation catalyst were add to the mixture obtained above and further mixed using FlackTek SpeedMixer^^ (dual axis) at 3,500 rpm for 3 minutes to obtain a silicone composition, the Si-H / Vi molar ratio in the silicone composition is 2.00. Adhesion strength to PPS was evaluated using the silicone composition. The results are shown in Table 3.

[0110] clnventive Example 2>

[0111] A silicone composition was prepared in the same manner as in the inventive example 1 , except that the added amount of the (C1) a-silane compound was changed from 1.80 parts by weight to 0.90 parts by weight in the step 2. Adhesion strength to PPS was evaluated using the silicone composition. The results are shown in Table 3.

[0112] <Comparative Example 1>

[0113] A silicone composition was prepared in the same manner as in the inventive example 1 , except that both 1 .80 parts by weight of the silane-2 and 1 .80 parts by weight of the silane-3 were used instead of 1.80 parts by weight of the (C1) a-silane compound in the step 2. Adhesion strength to PPS was evaluated using the silicone composition. The results are shown in Table 3.

[0114] <Comparative Example 2>

[0115] A silicone composition was prepared in the same manner as in the inventive example 1 , except that both 3.60 parts by weight of the silane-2 and 3.60 parts by weight of the silane-3 were used instead of 1.80 parts by weight of the (C1) a-silane compound in the step 2. Adhesion strength to PPS was evaluated using the silicone composition. The results are shown in Table 3.

[0116] <Comparative Example 3>

[0117] A silicone composition was prepared in the same manner as in the Inventive Example 1, except that 1.80 parts by weight of the silane-4 was used instead of 1.80 parts by weight ofthe (C1) a-silane compound in the step 2. Adhesion strength to PPS was evaluated using the silicone composition. The results are shown in Table 3.

[0118] <Comparative Example 4>

[0119] A silicone composition was prepared in the same manner as in the Inventive Example 1, except that 3.60 parts by weight of the silane-4 was used instead of 1.80 parts by weight of the (C1) a-silane compound in the step 2. Adhesion strength to PPS was evaluated using the silicone composition. The results are shown in Table 3.

[0120] Table 3

[0121] It can be seen from the above Table 3 that it was possible to provide a silicone composition that can form a cured product having good adhesion strength to a PPS substrate in the Inventive Examples 1 and 2 in which the used silicone compositions contained components (A) to (D). On the other hand, it can be seen from the above Table 3 that the cured product has inferior adhesion strength to a PPS substrate in the Comparative Examples 1 to 4 in which the used silicone compositions do not contain the (C) a-silane compound.INDUSTRIAL APPLICABILITY

[0122] According to the present disclosure, it is possible to provide a curable silicone composition that can form a cured product having good adhesion strength to a PPS substrate. According to the present disclosure, it is possible to provide a cured product having good adhesion strength to a PPS substrate. Moreover, according to the present disclosure, it is possible to provide a composite in which a cured product and a PPS substrate are well adhered to each other.

Claims

CLAIMS1. A curable silicone composition comprising:(A) an organopolysiloxane having at least two alkenyl groups per molecule;(B) an organopolysiloxane having an average of two or more silicone atom-bonded hydrogen atoms per molecule and free of alkenyl groups;(C) an a-silane compound indicated by formula (I), shown below, CH2=CH-COO-CH2-Si(CH3)n(OR)3_n(I) where, in the formula (I), R is an optionally substituted alkyl group, and n is 0 or 1; and(D) a curing catalyst.

2. The curable silicone composition according to claim 1, wherein the content of the (A) organopolysiloxane is from 10.00 to 90.00 wt.%, based on the total weight of the curable silicone composition.

3. The curable silicone composition according to claim 1, wherein the ratio of the number of moles of the silicone atom-bonded hydrogen atoms in the (B) organopolysiloxane per 1 mole of the alkenyl groups in the (A) organopolysiloxane is from 0.30 to 5.00.

4. The curable silicone composition according to claim 1, wherein the R is a methyl group, and the n is 0 in the formula (I).

5. The curable silicone composition according to claim 1, wherein the content of the (C) a- silane compound is from 0.10 to 5.00 wt.%, based on the total weight of the curable silicone composition.

6. The curable silicone composition according to claim 1, wherein the (D) curing catalyst includes at least one selected from the group consisting of a hydrosilylation catalyst and a condensation catalyst.

7. The curable silicone composition according to claim 1, wherein the (D) curing catalyst include a hydrosilylation catalyst selected from the group consisting of (methylcyclopentadienyl) trimethyl platinum (IV), (cyclo pentadienyl) trimethyl platinum (IV), (1,2,3,4,5-pentamethyl cyclopentadienyl) trimethyl platinum (IV), (cyclopentadienyl) dimethylethyl platinum (IV), (cyclopentadienyl) dimethylacetyl platinum (IV), (trimethylsilyl cyclopentadienyl) trimethyl platinum (IV), (methoxycarbonyl cyclopentadienyl) trimethyl platinum (IV), (dimethylsilyl cyclopentadienyl) trimethylcyclopentadienyl platinum (IV), trimethyl (acetylacetonato) platinum (IV), trimethyl (3,5-heptanedionate) platinum (IV), trimethyl (methylacetoacetate) platinum (IV),bis(acetylacetonato) platinum (II), bis(2,4-pentanedionato) platinum (II), bis(2,4-hexanedionato) platinum (II), bis(2,4-heptanedionato) platinum (II), bis(3,5-heptanedionato) platinum (II), bis(1- phenyl-1,3-butanedionato) platinum (II), bis(1,3-diphenyl-1,3-propanedionato) platinum (II), bis(hexafluoroacetylacetonato) platinum (II), and combinations thereof.

8. The curable silicone composition according to claim 1, further comprising:(E) a siloxane compound having a silicon atom-bonded hydrogen atom and a trialkoxysilyl group.

9. A cured product of the curable silicone composition according to any one of claims 1 to 8.

10. A composite comprising: a substrate made of polyphenylene sulfide; and the cured product according to claim 9 on the substrate.

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