Hot-melt curable silicone composition, sealing material, hot-melt adhesive, and optical semiconductor device

Abstract

This hot-melt curable silicone composition comprises: (A-1) an MQ resin-like alkenyl group-containing organopolysiloxane that is solid at room temperature and contains at least one alkenyl group per molecule; (A-2) a linear alkenyl group-containing organopolysiloxane that contains at least two alkenyl groups per molecule; (B-1) a linear organohydrogenpolysiloxane having silicon atom-bonded hydrogen atoms at both ends of the molecular chain; and (C) a curing catalyst, wherein (i) the content of component (B-1) is 60 mass% or more relative to the total mass of the organohydrogenpolysiloxane component having silicon atom-bonded hydrogen atoms, (ii) the amount of aryl groups in all silicon atom-bonded organic groups in the entirety of the organopolysiloxane component is 10 mol% or less, (iii) the content of component (A-1) is 65 mass% or more relative to the total mass of component (A-1) and component (A-2), and (iv) the content of the linear organohydrogenpolysiloxane having silicon atom-bonded hydrogen atoms only in side-chains of the molecular chain is 3 mass% or less relative to the total mass of the organohydrogenpolysiloxane component having silicon atom-bonded hydrogen atoms.

Description

Hot-melt curable silicone composition, sealing material, hot-melt adhesive, and optical semiconductor device

[0001] The present invention relates to a hot-melt curable silicone composition, more specifically, to a hot-melt curable silicone composition suitable for use as an encapsulant for optical semiconductors. The present invention also relates to an optical semiconductor device encapsulated with an encapsulant comprising a cured product of such a hot-melt curable silicone composition. This application claims priority based on Japanese Patent Application No. 2024-056798, filed March 29, 2024, the contents of which are incorporated herein by reference.

[0002] Curable silicone compositions are used in a wide range of industrial fields because they cure to form cured products that have excellent heat resistance, cold resistance, electrical insulation, weather resistance, water resistance, and transparency. In particular, the cured products are less susceptible to discoloration than other organic materials and show little deterioration in physical properties such as durability, so they are widely used as silicone encapsulants for optical materials, particularly in optical semiconductor devices such as light-emitting diodes (LEDs).

[0003] Hot-melt silicones are also used as sealants and hot-melt adhesives for semiconductor devices. These silicones are curable, non-fluid at room temperature, can be molded into sheets or films, and melt and become fluid when heated.

[0004] For example, Patent Document 1 describes a hot-melt silicone that is non-flowable at 25°C and has a melt viscosity of 5,000 Pa s or less at 100°C, which is obtained by subjecting (A) an alkenyl-containing organopolysiloxane in which 10 mol % or more of all silicon-bonded organic groups are phenyl groups and (B) an organopolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule {an amount such that 0.2 to 0.7 moles of silicon-bonded hydrogen atoms are present per mole of alkenyl groups in component (A)} to a hydrosilylation reaction in the presence of (C) a hydrosilylation catalyst {an amount sufficient to promote the hydrosilylation reaction between components (A) and (B)}.

[0005] In addition, Patent Document 2 discloses (A) an average unit formula: (R 1 3SiO1 / 2 ) a (R 2 2SiO 2 / 2 ) b (R 3 SiO 3 / 2 ) c (SiO 4 / 2 ) d (R 4 O 1 / 2 ) e (In the formula, R 1 , R 2 , R 3 are the same or different, a phenyl group, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, provided that R 1 40 mol % or less of R 2 30 mol % or more of R 3 10 mol % or less of R are alkenyl groups, 1 , R 2 , R 3 30 to 60 mol % of the total of R are phenyl groups, 4 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, a is a number from 0 to 0.2, b is a number from 0.2 to 0.5, c is a number from 0.3 to 0.8, d is a number from 0 to 0.5, e is a number from 0 to 0.1, and c+d is a number from 0.3 to 0.8, and a+b+c+d is 1; (B) 100 parts by mass of an organopolysiloxane represented by the average unit formula: (R 5 3SiO 1 / 2 ) f (R 5 2SiO 2 / 2 ) g (R 5 SiO 3 / 2 ) h (SiO 4 / 2 ) i (R 6 O 1 / 2 ) j (In the formula, R 5 are the same or different phenyl groups, alkyl groups having 1 to 6 carbon atoms, or alkenyl groups having 2 to 6 carbon atoms, provided that all R 5 10 to 70 mol % of the total R 5 at least one of R is an alkenyl group; 6is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, f is a number from 0.01 to 0.3, g is a number from 0.4 to 0.99, h is a number from 0 to 0.2, i is a number from 0 to 0.2, j is a number from 0 to 0.1, and h+i is a number from 0 to 0.2, and f+g+h+i is 1; (C) 0 to 150 parts by mass of an organopolysiloxane represented by the average composition formula: R 7 k H l SiO (4-k-l) / 2 (In the formula, R 7 is a phenyl group or an alkyl group having 1 to 6 carbon atoms, provided that all R 7 wherein 10 to 70 mol % of the alkenyl groups are phenyl groups, k is a number from 1.0 to 2.5, l is a number from 0.01 to 0.9, and k + l is a number from 1.5 to 3.0) (in an amount such that the number of silicon-bonded hydrogen atoms in this component is 0.5 to 2.0 moles per mole of alkenyl groups in components (A) and (B) combined)), and (D) a hydrosilylation reaction catalyst.

[0006] Patent Document 3 also describes (A) an alkenyl-containing organopolysiloxane having at least two alkenyl groups in one molecule, (B) a resinous organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule in an amount of 0.1 to 5 mass % relative to the total mass of the composition, and (C) an organopolysiloxane represented by the average unit formula (C-1): (R 1 3SiO 1 / 2 ) a (R 1 2SiO 2 / 2 ) b (R 1 SiO 3 / 2 ) c (In the formula, R 1 are the same or different alkyl groups, aryl groups, alkenyl groups, aralkyl groups, or epoxy group-containing organic groups, or alkoxy groups, provided that at least one R 1 is an alkenyl group, and at least one R 1is an epoxy group-containing organic group, and a, b, and c are numbers that satisfy the following relationships: 0≦a≦1.0, 0≦b≦1.0, 0≦c<0.9, and a+b+c=1. The document describes a solventless hot-melt curable silicone composition containing an additive represented by the formula (I), (D) a hydrosilylation catalyst, and (E) silica.

[0007] However, conventional hot-melt curable silicone compositions containing a high content of aryl groups have the problem of discoloring and losing transparency when heated.

[0008] WO2015 / 194158WO2016 / 035285 JP 2021-21058 A

[0009] An object of the present invention is to provide a hot-melt curable silicone composition that has a low aryl group content and can rapidly form a cured product with excellent transparency at low temperatures.

[0010] Another object of the present invention is to provide an encapsulant or hot melt adhesive containing the hot melt curable silicone composition of the present invention. Still another object of the present invention is to provide an optical semiconductor device encapsulated with the encapsulant of the present invention.

[0011]

[0009] In order to solve the above problems, the present inventors conducted extensive research and discovered that a curable organopolysiloxane composition of the present invention that contains at least the specified components (A-1), (A-2), (B-1), and (C) and satisfies the following conditions (i) to (iv) exhibits hot-melt properties and can rapidly form a cured product with excellent transparency at low temperatures, thereby completing the present invention.

[0012] Accordingly, the present invention provides a hot-melt curable silicone composition comprising: (A-1) an MQ resinous alkenyl-containing organopolysiloxane that is solid at room temperature and contains at least one alkenyl group per molecule; (A-2) a linear alkenyl-containing organopolysiloxane that contains at least two alkenyl groups per molecule; (B-1) a linear organohydrogenpolysiloxane that contains silicon-bonded hydrogen atoms at both molecular chain terminals; and (C) a curing catalyst, wherein: (i) the content of component (B-1) is 60 mass % or more based on the total mass of the organohydrogenpolysiloxane components having silicon-bonded hydrogen atoms; (ii) the amount of aryl groups in all silicon-bonded organic groups in all organopolysiloxane components is 10 mol % or less; and (iii) The hot-melt curable silicone composition relates to: (i) a content of component (A-1) of 65 mass% or more, based on the combined total mass of components (A-1) and (A-2); and (iv) a content of linear organohydrogenpolysiloxane having silicon-bonded hydrogen atoms only in side chains of the molecular chain of 3 mass% or less, based on the total mass of organohydrogenpolysiloxane components having silicon-bonded hydrogen atoms.

[0013] (A-1) The MQ resin-like alkenyl group-containing organopolysiloxane is preferably represented by the following average unit formula (I-2): Average unit formula (I): (R 2 3SiO 1 / 2 ) s1 (R 2 2nd Round 3 SiO 1 / 2 ) s2 (SiO 4 / 2 ) t (XO 1 / 2 ) u (In the formula, R 2 are the same or different monovalent hydrocarbon groups other than halogen-substituted or unsubstituted alkenyl groups, and R 3 is an alkenyl group, 0<s1<1, 0<s2<1, 0<t<1, 0≦u<0.4, and s1+s2+t=1, and u represents the number of (XO) groups when the total number of silicon atoms is 1 (the ratio of the number of (XO) groups to the total number of silicon atoms).

[0014] The content of (A-1) MQ resinous alkenyl-containing organopolysiloxane is preferably 40 to 90 mass % based on the total mass of the hot-melt curable silicone composition.

[0015] The (A-2) linear alkenyl-containing organopolysiloxane is preferably a linear organopolysiloxane in which both molecular chain terminals are blocked with alkenyl groups.

[0016] The linear organohydrogenpolysiloxane (B-1) preferably contains 1 to 100 siloxane units.

[0017] It is preferred that the composition further contains (B-2) an organohydrogenpolysiloxane consisting of only M units and Q units and having at least two silicon-bonded hydrogen atoms per molecule.

[0018] The content of (B-2) organohydrogenpolysiloxane consisting only of M units and Q units is preferably 40 mass % or less based on the total mass of all organohydrogenpolysiloxane components.

[0019] The molar ratio (H / Ak) of silicon-bonded alkenyl groups to silicon-bonded hydrogen atoms contained in the entire organopolysiloxane component is preferably less than 1.2.

[0020] The present invention also relates to a sealant or hot melt adhesive comprising the hot melt curable silicone composition of the present invention.

[0021] The present invention also relates to an optical semiconductor device encapsulated with the encapsulant according to the present invention.

[0022] The present invention provides a hot-melt curable silicone composition that has a low aryl group content and is capable of rapidly forming a cured product with excellent transparency at low temperatures.

[0023] [Hot-melt curable silicone composition] The hot-melt curable silicone composition of the present invention comprises at least: (A-1) an MQ resinous alkenyl-group-containing organopolysiloxane that is solid at room temperature and contains at least one alkenyl group per molecule; (A-2) a linear alkenyl-group-containing organopolysiloxane that contains at least two alkenyl groups per molecule; (B-1) a linear organohydrogenpolysiloxane that contains silicon-bonded hydrogen atoms at both molecular chain terminals; and (C) a curing catalyst, in which: (i) the content of the (B-1) linear organohydrogenpolysiloxane is 60 mass % or more based on the total mass of the organohydrogenpolysiloxane component having silicon-bonded hydrogen atoms; (ii) the amount of aryl groups in all silicon-bonded organic groups in all organopolysiloxane components is 10 mol % or less; and (iii) The hot-melt curable silicone composition relates to: (A-1) a content of MQ resinous alkenyl group-containing organopolysiloxane is 65 mass% or more, based on the combined total mass of components (A-1) and (A-2); and (iv) a content of linear organohydrogenpolysiloxane having silicon-bonded hydrogen atoms only in side chains of the molecular chain is 3 mass% or less, based on the total mass of organohydrogenpolysiloxane components having silicon-bonded hydrogen atoms.

[0024] Each component of the hot-melt curable silicone composition of the present invention will now be described in detail.

[0025] (A-1) MQ Resin-Type Alkenyl-Containing Organopolysiloxane That Is Solid at Room Temperature and Contains at Least One Alkenyl Group Per Molecule Component (A-1) is an MQ Resin-Type Alkenyl-Containing Organopolysiloxane that contains at least two alkenyl groups per molecule. The hot-melt curable silicone composition of the present invention may contain one type of (A-1) alkenyl-group-containing MQ resin, or two or more types of (A-1) alkenyl-group-containing MQ resins. Component (A-1) may contain at least two alkenyl groups per molecule.

[0026] In this specification, resinous means having a branched or three-dimensional network structure in the molecular structure. In one embodiment, resinous means having a ratio of R—SiO to all siloxane units in one molecule. 3 / 2 Siloxane units (T units) represented by the formula: and SiO 4 / 2 The proportion of siloxane units (Q units) represented by the formula: is 10% or more, preferably 20% or more, and more preferably 30% or more.

[0027] In this specification, MQ resin-like material refers to R3-SiO 1 / 2 Siloxane units (M units) represented by the formula: and SiO 4 / 2 It means an organopolysiloxane consisting only of siloxane units (Q units) represented by the following formula: In this specification, R in the siloxane unit represents a silicon atom-bonded organic group, for example, a monovalent hydrocarbon group.

[0028] The MQ resin-like alkenyl-containing organopolysiloxane of component (A-1) is solid at room temperature, which in this specification means 25°C.

[0029] Examples of alkenyl groups contained in component (A-1) include alkenyl groups having 2 to 12 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl groups, with vinyl groups being preferred.

[0030] Examples of organic groups bonded to silicon atoms other than alkenyl groups contained in component (A-1) include halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, such as alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms, such as fluorine, chlorine, or bromine. The silicon atoms in component (A-1) may contain small amounts of hydroxyl groups or alkoxy groups, such as methoxy and ethoxy, as long as the objectives of the present invention are not impaired. The silicon-bonded organic group other than the alkenyl group in component (A-1) is preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly methyl groups. In one embodiment, component (A-1) does not include an epoxy-containing organic group as an organic group bonded to a silicon atom.

[0031] In one embodiment of the present invention, the hot-melt curable silicone composition comprises two types of (A-1) MQ resinous alkenyl-containing organopolysiloxanes.

[0032] In a preferred embodiment of the present invention, the MQ resin-like alkenyl group-containing organopolysiloxane of component (A-1) can be preferably represented by the following average unit formula (I-1): Average unit formula (I-1): (R 1 3SiO 1 / 2 ) s (SiO 4 / 2 ) t (XO 1 / 2 ) u In the formula, R 1 are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, provided that at least one R 1is an alkenyl group, and 0<s<1, 0<t<1, 0≦u<0.4, and s+t=1. u represents the number of (XO) groups (the ratio of the number of (XO) groups to the total number of silicon atoms) when the total number of silicon atoms is 1. In addition, in this specification, the term "unit formula" refers to (SiO x / 2 ) (where x is an integer of 1 to 4), and the "structural formula" is a chemical formula that shows the actual number of siloxane units in the molecule.

[0033] R in the above formula (I-1) 1 Examples of halogen-substituted or unsubstituted monovalent hydrocarbon groups include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl; alkenyl groups having 2 to 12 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms, such as fluorine, chlorine, or bromine. R 1 is preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly a methyl group, and alkenyl groups having 2 to 6 carbon atoms, particularly a vinyl group.

[0034] In the above formula (I-1), X is a hydrogen atom or an alkyl group. The alkyl group for X is preferably an alkyl group having 1 to 3 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, and a propyl group.

[0035] In formula (I-1), s is preferably in the range of 0.2≦s≦0.9, more preferably 0.3≦s≦0.8, and even more preferably 0.4≦s≦0.7. In formula (I-1), t is preferably in the range of 0.1≦t≦0.8, more preferably 0.2≦t≦0.7, and particularly 0.3≦t≦0.6. In formula (I-1), u is preferably in the range of 0≦u≦0.3, more preferably 0≦u≦0.2, and particularly 0≦u≦0.1.

[0036] In another preferred embodiment of the present invention, the MQ resin-like alkenyl-containing alkynylpolysiloxane of component (A-1) can be preferably represented by the following average unit formula (I-2): Average unit formula (I): (R 2 3SiO 1 / 2 ) s1 (R 2 2nd Round 3 SiO 1 / 2 ) s2 (SiO 4 / 2 ) t (XO 1 / 2 ) u In the formula, R 2 are the same or different monovalent hydrocarbon groups other than halogen-substituted or unsubstituted alkenyl groups, and R 3 is an alkenyl group, where 0 < s1 < 1, 0 < s2 < 1, 0 < t < 1, 0 ≦ u < 0.4, and s1 + s2 + t = 1. u represents the number of (XO) groups when the total number of silicon atoms is 1 (the ratio of the number of (XO) groups to the total number of silicon atoms).

[0037] R in the above formula (I-2) 2Examples of the halogen-substituted or unsubstituted monovalent hydrocarbon group other than an alkenyl group include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms, such as fluorine, chlorine, or bromine. 2 is preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly methyl groups.

[0038] R in the above formula (I-2) 3 Examples of the alkenyl group include alkenyl groups having 2 to 12 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl groups, and preferably vinyl.

[0039] In the above formula (I-2), X is a hydrogen atom or an alkyl group. The alkyl group for X is preferably an alkyl group having 1 to 3 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, and a propyl group.

[0040] In formula (I-2), s1 is preferably in the range of 0.2≦s1≦0.7, more preferably 0.3≦s1≦0.6, and even more preferably 0.35≦s1≦0.55. In formula (I-2), s2 is preferably in the range of 0.01≦s2≦0.2, more preferably 0.02≦s2≦0.15, and even more preferably 0.03≦s2≦0.1. In formula (I-2), t is preferably in the range of 0.2≦t≦0.8, more preferably 0.3≦t≦0.7, and particularly 0.4≦t≦0.6. In formula (I-2), u is preferably in the range of 0≦u≦0.3, more preferably 0≦u≦0.2, and particularly 0≦u≦0.1.

[0041] The alkenyl group content of all silicon-bonded organic groups in the MQ resin-like alkenyl-group-containing organopolysiloxane of component (A-1) is not particularly limited, but may be, for example, 1 mol% or more, preferably 3 mol% or more, and more preferably 5 mol% or more of the total silicon-bonded organic groups, and 30 mol% or less, preferably 20 mol% or less, and more preferably 15 mol% or less of the total silicon-bonded organic groups. The alkenyl group content can be determined, for example, by analytical methods such as Fourier transform infrared spectroscopy (FT-IR) or nuclear magnetic resonance (NMR), or by the titration method described below. In this specification, the upper and lower limits of the numerical ranges can be arbitrarily combined to set the numerical range.

[0042] This section explains how to quantify the amount of alkenyl groups in each component using titration. The alkenyl group content in organopolysiloxane components can be accurately determined using a titration method commonly known as the Wyss method. The principle is as follows: First, alkenyl groups in the organopolysiloxane raw material are subjected to an addition reaction with iodine monochloride as shown in equation (1). Next, excess iodine monochloride is reacted with potassium iodide to liberate iodine as shown in equation (2). The liberated iodine is then titrated with sodium thiosulfate solution. Equation (1) CH2 = CH- + 2ICl → CH2I-CHCl- + ICl (excess) Equation (2) ICl + KI → I2 + KCl The amount of alkenyl groups in a component can be quantified from the difference between the amount of sodium thiosulfate required for titration and the titer amount of a separately prepared blank solution.

[0043] In one embodiment of the present invention, the MQ resin-like alkenyl-containing organopolysiloxane of component (A-1) is characterized by a low aryl group content. For example, the aryl group content of component (A) (the mole percent of aryl groups relative to all silicon-bonded organic groups) can be 20 mole percent or less, preferably 10 mole percent or less, more preferably 5 mole percent or less, even more preferably 3 mole percent or less, and particularly 1 mole percent or less. In a preferred embodiment, component (A-1) does not contain aryl groups. Note that, in this specification, the aryl group content can be determined, for example, by analysis using a Fourier transform infrared spectrophotometer (FT-IR) or nuclear magnetic resonance (NMR).

[0044] The weight average molecular weight of the MQ resin-like alkenyl group-containing organopolysiloxane of component (A-1) is not particularly limited, but is, for example, in the range of 2,000 to 100,000. In this specification, the weight average molecular weight can be measured by GPC. Typically, MQ resin-like organopolysiloxanes with a weight average molecular weight of about 1,000 or more are solid at room temperature. In a preferred embodiment, the weight average molecular weight of the MQ resin-like alkenyl group-containing organopolysiloxane of component (A-1) is in the range of 1,000 to 100,000.

[0045] Furthermore, the proportion of Q units relative to the total of M units and Q units in the MQ resin-like alkenyl group-containing organopolysiloxane of component (A-1) is not particularly limited, but is preferably greater than 40%, more preferably 45% or greater, and even more preferably 47% or greater. In general, the greater the proportion of Q units in the molecule, the more likely it is to be a solid at room temperature.

[0046] The content of component (A-1) is not particularly limited, but is typically 40% by mass or more, preferably 45% by mass or more, and more preferably 50% by mass or more, based on the total mass of the hot-melt curable silicone composition of the present invention. Furthermore, the content of component (A-1) is preferably 90% by mass or less, preferably 80% by mass or less, and more preferably 75% by mass or less, based on the total mass of the hot-melt curable silicone composition.

[0047] The content of component (A-1) is typically 40 to 90 mass %, preferably 45 to 80 mass %, and more preferably 50 to 75 mass %, based on the total mass of the hot-melt curable silicone composition of the present invention.

[0048] In another embodiment, the content of component (A-1) is not particularly limited, but is typically 40% by mass or more, preferably 45% by mass or more, and more preferably 50% by mass or more, based on the total mass of all organopolysiloxane components in the composition of the present invention. Furthermore, the content of component (A-1) is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less, based on the total mass of all organopolysiloxane components in the composition of the present invention. In this specification, the term "all organopolysiloxane components" includes alkenyl group-containing organopolysiloxanes and organohydrogenpolysiloxanes.

[0049] In another embodiment, the content of component (A-1) is typically 40 to 90 mass %, preferably 45 to 80 mass %, and more preferably 50 to 75 mass %, based on the total mass of all organopolysiloxane components in the composition of the present invention.

[0050] (A-2) Linear Alkenyl Group-Containing Organopolysiloxane Containing at Least Two Alkenyl Groups Per Molecule Component (A-2) is a linear alkenyl group-containing organopolysiloxane containing at least two alkenyl groups per molecule. The hot-melt curable silicone composition of the present invention may contain one type of linear alkenyl group-containing organopolysiloxane (A-2), or may contain two or more types of linear alkenyl group-containing organopolysiloxanes (A-2).

[0051] The alkenyl groups and silicon-bonded organic groups other than alkenyl groups contained in component (A-2) are the same as those described above for component (A-1), and the same description as for component (A-1) can also be applied.

[0052] In a preferred embodiment, the linear alkenyl group-containing organopolysiloxane of component (A-2) contains 50 or more siloxane units. In a preferred embodiment, the linear alkenyl group-containing organopolysiloxane of component (A-2) contains 50 to 2000 siloxane units, preferably 75 to 1500 siloxane units, more preferably 100 to 1300 siloxane units, and even more preferably 150 to 1200 siloxane units.

[0053] In a preferred embodiment, the viscosity of the linear alkenyl group-containing organopolysiloxane of component (A-2) at 25°C is 30 mPa·s or higher. More preferably, the viscosity of the linear alkenyl group-containing organopolysiloxane of component (A-2) at 25°C is 50 mPa·s or higher, and even more preferably 80 mPa·s or higher. There is no particular upper limit to the viscosity of the linear alkenyl group-containing organopolysiloxane of component (A-2) at 25°C, but it is typically 1,000,000 mPa·s or lower, and preferably 700,000 mPa·s or lower. In this specification, the viscosity of the organopolysiloxane component can be measured at 25°C at an ambient pressure of 1013 mbar using an Anton Paar rheometer model MCR302 in accordance with ISO 3219.

[0054] In a preferred embodiment of the present invention, the linear alkenyl group-containing organopolysiloxane of component (A-2) can be preferably represented by the following average structural formula (II-1): Average structural formula (II-1): R 1 3SiO(R 1 SiO 2 / 2 ) n SiR 1 3 (In formula (II-1), R 1 are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, provided that in one molecule, R at the molecular chain terminal 1 at least one of which is an alkenyl group, and n is a number in the range of 50 to 2000.

[0055] In the above formula (II-1), R 1The alkenyl group and halogen-substituted or unsubstituted monovalent hydrocarbon group in formula (I-1) can be the same as those in formula (I-1).

[0056] In the above formula (II-1), n ​​is preferably a number in the range of 75 to 1,500, more preferably a number in the range of 100 to 1,300, and even more preferably a number in the range of 150 to 1,200.

[0057] In a preferred embodiment of the present invention, the linear alkenyl-containing organopolysiloxane of component (A-2) may be a linear organopolysiloxane capped at both molecular chain ends with alkenyl groups, i.e., containing alkenyl groups only at both molecular chain ends. The linear organopolysiloxane of component (A-2) may contain alkenyl groups at side chains on the molecular chain (i.e., R2-SiO 2 / 2 The siloxane units (D units) represented by the formula (I) may or may not contain alkenyl groups, but preferably do not. In a more preferred embodiment, the linear alkenyl-containing organopolysiloxane of component (A-2) contains alkenyl groups only at both molecular chain terminals, with two alkenyl groups per molecule.

[0058] Therefore, in a preferred embodiment of the present invention, the linear alkenyl group-containing organopolysiloxane of component (A-2) can be preferably represented by the following average structural formula (II-2): Average structural formula (II-2): R 3 R 2 2SiO(R 2 2SiO 2 / 2 ) n SiR 3 R 2 2 (In formula (II-2), R 2 are the same or different monovalent hydrocarbon groups other than halogen-substituted or unsubstituted alkenyl groups, and R 3 is an alkenyl group, and n is a number in the range of 50 to 2000).

[0059] In the above formula (II-2), R 2 Monovalent hydrocarbon groups other than alkenyl groups and R 3 As the alkenyl group, the same as in the above formula (I-2) can be applied.

[0060] In the above formula (II-2), the same preferable range of n as in the above formula (II-1) can be applied.

[0061] The alkenyl group content (mol % of alkenyl groups relative to all silicon-bonded organic groups) contained in the linear organopolysiloxane of component (A-2) can be designed as desired, but is typically from 0.01 mol % to 2 mol %.

[0062] In one embodiment of the present invention, the linear alkenyl-containing organopolysiloxane of component (A-2) is characterized by a low aryl group content. For example, the aryl group content of component (A-2) (the mole percent of aryl groups relative to all silicon-bonded organic groups) is 20 mole percent or less, preferably 10 mole percent or less, more preferably 5 mole percent or less, even more preferably 3 mole percent or less, and particularly preferably 1 mole percent or less. In a preferred embodiment, component (A-2) does not contain any aryl groups.

[0063] The content of the linear alkenyl group-containing organopolysiloxane of component (A-2) is not particularly limited, but is preferably 1 mass % or more, more preferably 2 mass % or more, and even more preferably 3 mass % or more, based on the total mass of the hot-melt curable silicone composition of the present invention. Furthermore, the content of component (A-2) is 40 mass % or less, preferably 35 mass % or less, and even more preferably 30 mass % or less, based on the total mass of the hot-melt curable silicone composition of the present invention.

[0064] There are no particular limitations on the amount of linear alkenyl group-containing organopolysiloxane contained in component (A-2), but it can be 1 to 40 mass %, preferably 2 to 35 mass %, and more preferably 3 to 30 mass %, based on the total mass of the hot-melt curable silicone composition of the present invention.

[0065] In another embodiment, the content of the linear alkenyl group-containing organopolysiloxane of component (A-2) may be 1% by mass or more, preferably 2% by mass or more, and more preferably 3% by mass or more, based on the total mass of all organopolysiloxane components in the composition of the present invention. Furthermore, the content of component (A-2) may be 40% by mass or less, preferably 35% by mass or less, and more preferably 30% by mass or less, based on the total mass of all organopolysiloxane components in the composition of the present invention.

[0066] In another embodiment, the content of the linear alkenyl group-containing organopolysiloxane of component (A-2) is 1 to 40 mass %, preferably 2 to 35 mass %, and more preferably 3 to 30 mass % or more, based on the total mass of all organopolysiloxane components in the composition of the present invention.

[0067] In the present invention, in order to achieve excellent hot-melt properties, the content of (iii) component (A-1) is 65% by mass or more, based on the total mass of components (A-1) and (A-2). In a particularly preferred embodiment, the content of component (A-1) is 70% by mass or more, based on the total mass of components (A-1) and (A-2). Furthermore, the content of component (A-1) relative to the total mass of components (A-1) and (A-2) is usually less than 100% by mass, and preferably 95% by mass or less.

[0068] (B-1) Linear Organohydrogenpolysiloxane Containing Silicon-Bonded Hydrogen Atoms at Both Molecular Chain Terminals Component (B-1) is a linear organohydrogenpolysiloxane containing silicon-bonded hydrogen atoms at both molecular chain terminals. The hot-melt curable silicone composition of the present invention may contain one type of linear organohydrogenpolysiloxane (B-1), or may contain two or more types of linear organohydrogenpolysiloxane (B-1).

[0069] Silicon-bonded organic groups other than silicon-bonded hydrogen atoms contained in component (B-1) include halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, such as alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms, such as fluorine, chlorine, or bromine. The silicon atoms in component (B-1) may contain small amounts of hydroxyl groups or alkoxy groups, such as methoxy and ethoxy, as long as the objective of the present invention is not impaired. The organic groups bonded to silicon atoms other than silicon-bonded hydrogen atoms in component (B-1) are preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly methyl groups.

[0070] In one embodiment, the linear organohydrogenpolysiloxane of component (B-1) contains 1 to 100 siloxane units, preferably 3 to 80 siloxane units, and more preferably 5 to 60 siloxane units.

[0071] The linear organohydrogenpolysiloxane of component (B-1) has silicon-bonded hydrogen atoms at the molecular chain terminals, and preferably has silicon-bonded hydrogen atoms only at the molecular chain terminals. The linear organohydrogenpolysiloxane of component (B-1) has silicon-bonded hydrogen atoms at the molecular chain side chains (i.e., R2-SiO 2 / 2 The siloxane units (D units) represented by the formula (B-1) may or may not contain silicon-bonded hydrogen atoms, but preferably do not. In a more preferred embodiment, the linear organohydrogenpolysiloxane of component (B-1) has two silicon-bonded hydrogen atoms per molecule.

[0072] In one embodiment of the present invention, the linear organohydrogenpolysiloxane of component (B-1) can be represented by the following average structural formula (III): Average structural formula (III): R 4 2HSiO(R 4 2SiO 2 / 2 ) n SiHR 4 2 In formula (III), R 4 are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, and n is 1 to 100.

[0073] R in the above formula (III) 4 The monovalent hydrocarbon group other than the halogen-substituted or unsubstituted alkenyl group is R 2 The same can be applied.

[0074] In the above formula (III), n is preferably 3-80, and more preferably 5-60.

[0075] In one embodiment, component (B-1) comprises an aryl group-containing linear organohydrogenpolysiloxane containing silicon-bonded aryl groups. The aryl group-containing linear organopolysiloxane of component (B-1) preferably contains aryl groups at the molecular side chains, and may or may not contain aryl groups at the molecular chain terminals, but preferably does not. In one embodiment, component (B-1) comprises ArSiO 2 / 2 (where Ar represents an aryl group), and the component (B-1) contains a linear organohydrogenpolysiloxane containing a structural unit in which two aryl groups substitute for one silicon atom. In one embodiment, the component (B-1) contains a linear organohydrogenpolysiloxane that does not contain an aryl group, and an aryl group-containing linear organohydrogenpolysiloxane. Examples of the aryl group include aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl, with phenyl being preferred.

[0076] In one embodiment of the present invention, when component (B-1) contains an aryl group-containing linear organohydrogenpolysiloxane, the content of aryl groups in all silicon-bonded organic groups in the aryl group-containing linear organohydrogenpolysiloxane is not particularly limited, but may be, for example, 10 mol % or more, preferably 15 mol % or more, and more preferably 20 mol % or more of the total silicon-bonded organic groups, and may be 50 mol % or less, preferably 40 mol %, and more preferably 30 mol % or less of the total silicon-bonded organic groups.

[0077] The content of component (B-1) is not particularly limited, but is typically 1% by mass or more, preferably 3% by mass or more, and more preferably 5% by mass or more, based on the total mass of the hot-melt curable silicone composition of the present invention. Furthermore, the content of component (B-1) is preferably 40% by mass or less, preferably 30% by mass or less, and more preferably 25% by mass or less, based on the total mass of the hot-melt curable silicone composition.

[0078] The content of component (B-1) is typically 1 to 40 mass %, preferably 3 to 30 mass %, and more preferably 5 to 25 mass %, based on the total mass of the hot-melt curable silicone composition of the present invention.

[0079] In another embodiment, the content of component (B-1) is not particularly limited, but is typically 1% by mass or more, preferably 3% by mass or more, and more preferably 5% by mass or more, based on the total mass of all organopolysiloxane components in the composition of the present invention. Also, the content of component (B-1) is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, based on the total mass of all organopolysiloxane components in the composition of the present invention.

[0080] In another embodiment, the content of component (B-1) is typically 1 to 40 mass %, preferably 3 to 30 mass %, and more preferably 5 to 25 mass %, based on the total mass of all organopolysiloxane components in the composition of the present invention.

[0081] From the viewpoint of achieving excellent curability, the hot-melt curable silicone composition of the present invention is characterized by a high content of linear organohydrogenpolysiloxane (component (B-1)) among the organohydrogenpolysiloxanes that act as crosslinkers for the alkenyl group-containing organopolysiloxane. Specifically, (i) the content of linear organohydrogenpolysiloxane (B-1) is 60 mass% or more based on the total mass of organohydrogenpolysiloxane components having silicon-bonded hydrogen atoms.

[0082] Furthermore, from the viewpoint of achieving excellent curability, the hot-melt curable silicone composition according to the present invention is characterized by a low content of linear organohydrogenpolysiloxanes having silicon-bonded hydrogen atoms only in the side chains of the molecular chain. The linear organohydrogenpolysiloxanes having silicon-bonded hydrogen atoms only in the side chains of the molecular chain are, for example, R2-SiO 2 / 2 (iv) refers to a linear organohydrogenpolysiloxane having silicon-bonded hydrogen atoms only in siloxane units (D units) represented by the formula (I), and not having silicon-bonded hydrogen atoms at the molecular chain terminals (i.e., M units). Specifically, the content of linear organohydrogenpolysiloxanes having silicon-bonded hydrogen atoms only in molecular side chains is 3% by mass or less, preferably 2% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and especially 0.1% by mass or less, based on the total mass of the organohydrogenpolysiloxane components having silicon-bonded hydrogen atoms. Furthermore, in a particularly preferred embodiment of the present invention, the hot-melt curable silicone composition according to the present invention does not contain a linear organohydrogenpolysiloxane having silicon-bonded hydrogen atoms only in molecular side chains.

[0083] (Other Organopolysiloxane Components) (B-2) MQ Resin-Type Organohydrogenpolysiloxanes Composed Only of M and Q Units and Having at Least Two Silicon-Bonded Hydrogen Atoms Per Molecule The hot-melt curable silicone composition of the present invention may contain, as component (B-2), an organohydrogenpolysiloxane composed only of M and Q units and having at least two silicon-bonded hydrogen atoms per molecule. The hot-melt curable silicone composition of the present invention may contain a single organohydrogenpolysiloxane composed only of M and Q units of component (B-2), or may contain two or more organohydrogenpolysiloxanes composed only of M and Q units of component (B-2).

[0084] The organic groups bonded to silicon atoms other than silicon-bonded hydrogen atoms contained in component (B-2) are the same as those described above for component (B-1), and the same description as for component (B-1) can be applied.

[0085] In a preferred embodiment of the present invention, the organohydrogenpolysiloxane of component (B-2) consisting only of M units and Q units can be preferably represented by the following average unit formula (IV-1): Average unit formula (IV-1): (R 5 3SiO 1 / 2 ) s (SiO 4 / 2 ) t (XO 1 / 2 ) u In the formula, R 5 are hydrogen atoms or the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, provided that at least two R 5 is a hydrogen atom, and 0<s<1, 0<t<1, 0≦u<0.4, and s+t=1. u means the number of (XO) groups when the total number of silicon atoms is 1 (the ratio of the number of (XO) groups to the total number of silicon atoms).

[0086] In the above formula (IV-1), R 5 The monovalent hydrocarbon group other than the halogen-substituted or unsubstituted alkenyl group other than the alkenyl group of the above formula (I-2) is 2The same can be applied.

[0087] In the above formula (IV-1), X is a hydrogen atom or an alkyl group. The alkyl group for X is preferably an alkyl group having 1 to 3 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, and a propyl group.

[0088] In formula (IV-1), s is preferably in the range of 0.3≦s≦0.9, more preferably 0.4≦s≦0.8, and even more preferably 0.5≦s≦0.7. In formula (IV-1), t is preferably in the range of 0.1≦t≦0.7, more preferably 0.2≦t≦0.6, and particularly 0.3≦t≦0.5. In formula (IV-1), u is preferably in the range of 0≦u≦0.3, more preferably 0≦u≦0.2, and particularly 0≦u≦0.1.

[0089] In a preferred embodiment of the present invention, the organohydrogenpolysiloxane of component (B-2) consisting only of M units and Q units can be preferably represented by the following average unit formula (IV-2): Average unit formula (IV-2): (R 5 2HSiO 1 / 2 ) s (SiO 4 / 2 ) t (XO 1 / 2 ) u In the formula, R 5 , s, t, u, and X are as defined above in formula (IV-1).

[0090] The mass average molecular weight of the organohydrogenpolysiloxane of component (B-2) consisting only of M units and Q units is not particularly limited, but is, for example, in the range of 300 to 10,000, preferably in the range of 500 to 5,000, and more preferably in the range of 700 to 3,000.

[0091] In one embodiment of the present invention, the organohydrogenpolysiloxane (B-2) consisting only of M units and Q units is characterized by a low aryl group content. For example, the aryl group content (mol % of aryl groups in all silicon-bonded organic groups) of component (B-2) is 20 mol % or less, preferably 10 mol % or less, more preferably 5 mol % or less, even more preferably 3 mol % or less, and particularly 1 mol % or less. In a preferred embodiment, component (B-2) does not contain any aryl groups.

[0092] When the hot-melt curable silicone composition of the present invention contains (B-2) an organohydrogenpolysiloxane consisting only of M units and Q units, the content of component (B-2) is not particularly limited, but is preferably 0.5% by mass or more, more preferably 1% by mass or more, based on the total mass of the hot-melt curable silicone composition of the present invention or the total mass of all organopolysiloxane components in the composition. Furthermore, the content of component (B-2) may be 15% by mass or less, more preferably 10% by mass or less, based on the total mass of the hot-melt curable silicone composition or the total mass of all organopolysiloxane components in the composition.

[0093] The content of component (B-2) is typically 0.5 to 15% by mass, and preferably 1 to 10% by mass, based on the total mass of the hot-melt curable silicone composition of the present invention or the total mass of all organopolysiloxane components in the composition.

[0094] In another embodiment, when the hot-melt curable silicone composition of the present invention contains component (B-2), the content of component (B-2) can be 3% by mass or more, preferably 5% by mass or more, based on the total mass of all organohydrogenpolysiloxane components in the composition of the present invention. The content of component (B-2) can be 40% by mass or less, preferably 30% by mass or less, based on the total mass of all organohydrogenpolysiloxane components in the composition of the present invention.

[0095] In another embodiment, when the hot-melt curable silicone composition according to the present invention contains component (B-2), the content of component (B-2) is 3 to 40 mass %, and preferably 5 to 30 mass %, based on the total mass of all organohydrogenpolysiloxane components in the composition of the present invention.

[0096] (A-3) Cyclic Alkenyl Group-Containing Organopolysiloxane Containing at Least Two Alkenyl Groups Per Molecule The hot-melt curable silicone composition of the present invention may contain, as component (A-3), a cyclic alkenyl group-containing organopolysiloxane having at least two alkenyl groups per molecule. The hot-melt curable silicone composition of the present invention may contain one type of (A-3) cyclic alkenyl group-containing organopolysiloxane, or two or more types of (A-3) cyclic alkenyl group-containing organopolysiloxanes.

[0097] The alkenyl groups and silicon-bonded organic groups other than alkenyl groups contained in component (A-3) can be the same as those for component (A-1).

[0098] The cyclic alkenyl group-containing organopolysiloxane of component (A-3) preferably has an average structural formula (V): (R 1 2SiO) n (In formula (V), R 1 are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, provided that at least two R 1 is an alkenyl group, and n is 4 to 20).

[0099] In the above formula (V), R 1 The alkenyl group and halogen-substituted or unsubstituted monovalent hydrocarbon group in formula (I-1) can be the same as those in formula (I-1).

[0100] In the above formula (V), n is, for example, 4 to 15, preferably 4 to 10, and more preferably 4 to 6.

[0101] The alkenyl group content of all silicon-bonded organic groups in the cyclic alkenyl group-containing organopolysiloxane of component (A-3) can be designed as desired, but is typically 20 mol% or more, preferably 30 mol% or more, and even more preferably 40 mol% or more, and can be 80 mol% or less, preferably 70 mol% or less, and more preferably 60 mol% or less.

[0102] In one embodiment of the present invention, the cyclic alkenyl group-containing organopolysiloxane of component (A-3) is characterized by a low aryl group content. For example, the aryl group content of component (A-3) (the mole percent of aryl groups relative to all silicon-bonded functional groups) can be 20 mole % or less, preferably 10 mole % or less, more preferably 5 mole % or less, even more preferably 3 mole % or less, and particularly 1 mole % or less. In a preferred embodiment, component (A-3) does not contain any aryl groups.

[0103] When the hot-melt curable silicone composition according to the present invention contains (A-3) a cyclic alkenyl group-containing organopolysiloxane, the content of component (A-3) is not particularly limited, but is preferably 0.5% by mass or more, more preferably 1% by mass or more, based on the total mass of the hot-melt curable silicone composition according to the present invention or the total mass of all organopolysiloxane components in said composition. Furthermore, the content of component (A-3) is preferably 5% by mass or less, more preferably 3% by mass or less, based on the total mass of the hot-melt curable silicone composition or the total mass of all organopolysiloxane components in said composition.

[0104] The content of component (A-3) is typically 0.5 to 5 mass %, and preferably 1 to 3 mass %, based on the total mass of the hot-melt curable silicone composition of the present invention or the total mass of all organopolysiloxane components in the composition.

[0105] In another embodiment, when the hot-melt curable silicone composition of the present invention contains component (A-3), the content of component (A-3) can be 0.5% by mass or more, and preferably 1% by mass or more, based on the total mass of all alkenyl group-containing organopolysiloxane components in the composition of the present invention. Furthermore, the content of component (A-3) can be 5% by mass or less, and preferably 3% by mass or less, based on the total mass of all alkenyl group-containing organopolysiloxane components in the composition of the present invention.

[0106] In another embodiment, when the hot-melt curable silicone composition according to the present invention contains component (A-3), the content of component (A-3) is 0.5 to 5 mass %, and preferably 1 to 3 mass %, based on the total mass of all alkenyl group-containing organopolysiloxane components in the composition of the present invention.

[0107] (A-4) MQ Resin-Type Organopolysiloxanes That Are Liquid at Room Temperature The hot-melt curable silicone composition of the present invention may contain, as component (A-4), an MQ resin-type organopolysiloxane that is liquid at room temperature and consists solely of M units and Q units. The hot-melt curable silicone composition of the present invention may contain one MQ resin-type organopolysiloxane (component (A-4)), or two or more MQ resin-type organopolysiloxanes (component (A-4)). Note that, because component (A-4) is liquid at room temperature, it differs from component (A-1), an MQ resin-type alkenyl-group-containing organopolysiloxane that is solid at room temperature. Furthermore, because component (A-4) does not contain silicon-bonded hydrogen atoms in its molecule, it differs from component (B-2), an organohydrogenpolysiloxane that consists solely of M units and Q units.

[0108] The organic group bonded to the silicon atom in component (A-4) includes a halogen-substituted or unsubstituted monovalent hydrocarbon group, such as an alkyl group having 1 to 12 carbon atoms, such as 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 group, a cyclohexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, or a dodecyl group; a vinyl group, an allyl group, a butenyl group, a pentyl group, or a pentyl group; Examples of suitable organic groups include alkenyl groups having 2 to 12 carbon atoms, such as phenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms, such as fluorine, chlorine, or bromine. The silicon atoms in component (A-4) may contain small amounts of hydroxyl groups or alkoxy groups, such as methoxy and ethoxy, as long as the objectives of the present invention are not impaired. The organic groups bonded to the silicon atoms in component (A-4) are preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly methyl, and alkenyl groups having 2 to 12 carbon atoms, particularly vinyl. In one embodiment, component (A-4) does not include an epoxy group-containing organic group as an organic group bonded to a silicon atom, and in another embodiment, component (A-4) does not include an aryl group as an organic group bonded to a silicon atom.

[0109] In a preferred embodiment of the present invention, the MQ resinous organopolysiloxane of component (A-4) can be preferably represented by the following average unit formula (VI): Average unit formula (VI): (R 1 3SiO 1 / 2 ) s (SiO 4 / 2 ) t (XO 1 / 2 ) u In the formula, R 1are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, where 0 < s < 1, 0 < t < 1, 0 ≦ u < 0.4, and s + t = 1. u represents the number of (XO) groups when the total number of silicon atoms is 1 (the ratio of the number of (XO) groups to the total number of silicon atoms).

[0110] R in the above formula (VI) 1 and X may be the same as those in the above formula (I-1).

[0111] In formula (VI), s is preferably in the range of 0.4≦s≦0.95, more preferably 0.5≦s≦0.9, and even more preferably 0.55≦s≦0.85. In formula (VI), t is preferably in the range of 0.05≦t≦0.7, more preferably 0.1≦t≦0.6, and particularly 0.15≦t≦0.5. In formula (VI), u is preferably in the range of 0≦u≦0.3, more preferably 0≦u≦0.2, and particularly 0≦u≦0.1.

[0112] The mass average molecular weight of the MQ resin-like organopolysiloxane of component (A-4) is not particularly limited, but is, for example, in the range of 300 or more and less than 2,000. In this specification, the mass average molecular weight can be measured by GPC. Typically, an MQ resin-like organopolysiloxane with a mass average molecular weight of less than about 2,000 can be liquid at room temperature. In a preferred embodiment, the mass average molecular weight of the MQ resin-like organopolysiloxane of component (A-4) is in the range of 350 to 1,800.

[0113] Furthermore, the proportion of Q units relative to the total of M and Q units in the MQ resinous organopolysiloxane of component (A-4) is not particularly limited, but is preferably 40% or less. In general, the smaller the proportion of Q units in the molecule, the more likely it is to remain liquid at room temperature.

[0114] The content of component (A-4) is not particularly limited, but is typically 0.1% by mass or more, preferably 0.5% by mass or more, and more preferably 1% by mass or more, based on the total mass of the hot-melt curable silicone composition of the present invention or the total mass of all organopolysiloxane components in the composition. Furthermore, the content of component (A-4) is preferably 30% by mass or less, preferably 20% by mass or less, and more preferably 15% by mass or less, based on the total mass of the hot-melt curable silicone composition.

[0115] The content of component (A-4) is typically 0.1 to 30 mass %, preferably 0.5 to 20 mass %, and more preferably 1 to 15 mass %, based on the total mass of the hot-melt curable silicone composition of the present invention or the total mass of all organopolysiloxane components in the composition.

[0116] Furthermore, the hot-melt curable silicone composition of the present invention can also contain alkenyl-containing organopolysiloxanes with branched, resinous, and / or three-dimensional network structures other than MQ resins, as long as the effects of the present invention are not impaired.

[0117] In a preferred embodiment of the present invention, the ratio of silicon-bonded alkenyl groups to silicon-bonded hydrogen atoms (H / Ak) contained in all organopolysiloxane components of the hot-melt curable silicone composition is less than 1.2 moles of silicon-bonded hydrogen atoms per mole of silicon-bonded alkenyl groups, and is typically at least 0.50 moles, and preferably at least 0.55 moles.

[0118] The hot-melt curable silicone composition of the present invention is characterized by a low content of aryl groups in the organopolysiloxane component. Therefore, in (ii) the hot-melt curable silicone composition, the amount of aryl groups in all silicon-bonded organic groups in the entire organopolysiloxane component is 10 mol % or less, preferably 5 mol % or less, more preferably 1 mol % or less, even more preferably 0.5 mol % or less, and particularly preferably 0.1 mol % or less.

[0119] In a specific embodiment of the present invention, when the amount of aryl groups in the total silicon-bonded organic groups in all organopolysiloxane components of the hot-melt curable silicone composition of the present invention is 0.03 mol % or more, the linear organopolysiloxane of component (A-2) has a low viscosity. Specifically, when the amount of aryl groups in the total silicon-bonded organic groups in all organopolysiloxane components of the hot-melt curable silicone composition of the present invention is 0.03 mol % or more, the viscosity of component (A-2) is less than 10,000 mPa s at 25°C.

[0120] (C) Curing Catalyst The curing catalyst of component (C) is a curing catalyst for hydrosilylation reactions, and is a catalyst for accelerating the curing of the curable silicone composition of the present invention. Examples of this component (C) include platinum-based catalysts such as chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum-olefin complexes, platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complexes, and platinum-supported powders; palladium-based catalysts such as tetrakis(triphenylphosphine)palladium, palladium black, and mixtures with triphenylphosphine; and rhodium-based catalysts, with platinum-based catalysts being particularly preferred.

[0121] The amount of component (C) blended is a catalytic amount. More specifically, when a platinum catalyst is used as component (C), the amount of platinum atoms, relative to the total mass of the curable silicone composition of the present invention, is preferably at least 0.01 ppm, more preferably at least 0.1 ppm, and even more preferably at least 1 ppm. The amount of platinum atoms, relative to the total mass of the curable silicone composition of the present invention, is preferably no more than 20 ppm, more preferably no more than 15 ppm, even more preferably no more than 10 ppm, and especially preferably no more than 7 ppm.

[0122] (Other Components) The curable silicone composition of the present invention can contain optional components as long as they do not impair the objectives of the present invention. Examples of optional components include acetylene compounds, organophosphorus compounds, vinyl group-containing siloxane compounds, inorganic fillers such as crushed quartz, silica, magnesium carbonate, and diatomaceous earth, inorganic fillers obtained by hydrophobizing the surface of such inorganic fillers with organosilicon compounds, surface treatment agents, hydrosilylation reaction inhibitors, tackifiers, heat resistance agents, cold resistance agents, flame retardants, thixotropy agents, phosphors, and solvents. The amount of these optional components added is typically 0.001 to 20% by mass of the total composition.

[0123] The hydrosilylation reaction inhibitor is a component for inhibiting the hydrosilylation reaction of the curable silicone composition. Examples of such curing reaction inhibitors include alkyne alcohols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 2-phenyl-3-butyn-2-ol, 1-ethynyl-1-cyclohexanol, and 1-ethynyl-2-cyclohexanol; enyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; tetramethyltetravinylcyclotetrasiloxane and tetramethyltetrahexenylcyclotetrasiloxane. Examples of suitable hydrosilylation reaction inhibitors include alkenyl-containing low-molecular-weight siloxanes; alkynyloxysilanes such as methyl-tris(1,1-dimethylpropynyloxy)silane, vinyl-tris(1,1-dimethylpropynyloxy)silane, and methyl-tris(3-methyl-1-butyn-3-oxy)silane; maleic acid esters such as diallyl maleate and bis(2-ethylhexyl) maleate; and disulfide compounds having a disulfide structure such as di-dodecyl disulfide, di-decyl disulfide, and di-octyl disulfide. The hydrosilylation reaction inhibitor is preferably selected from alkyne alcohols and maleic acid esters, and particularly preferably contains an alkyne alcohol and a maleic acid ester. The amount of the reaction inhibitor added is typically 0.001 to 5% by mass of the total composition.

[0124] The hot-melt curable silicone composition of the present invention has the advantage that it can be cured by heating at low temperature for a short time. Specifically, the hot-melt curable silicone composition of the present invention can be fully cured by heating at 120°C for 2 hours, for example.

[0125] The hot-melt curable silicone composition of the present invention can be cured to form a cured product with good transparency. For example, a cured product of the curable silicone composition of the present invention can exhibit a light transmittance of more than 90% for light with a wavelength of 450 nm. The light transmittance of the cured product of the curable silicone composition can be determined, for example, by measuring the cured product with an optical path length of 1 using a spectrophotometer.

[0126] A B-stage film of the hot-melt curable silicone composition according to the present invention can exhibit good fluidity upon heating. For example, a B-stage film of the curable silicone composition according to the present invention can have a storage modulus (G') of less than 10,000 Pa upon heating at an appropriate temperature. The storage modulus of a B-stage film of the curable silicone composition can be determined, for example, using a rheometer equipped with a viscoelasticity measurement function.

[0127] B-stage films of the hot-melt curable silicone compositions of the present invention are solid at working temperatures.

[0128] The curable silicone composition of the present invention can be prepared by mixing the various components. The method for mixing the various components can be any conventionally known method, and is not particularly limited. For example, the composition can be prepared by mixing using a mixing device. There are no particular limitations on such mixing devices, and examples include single- or double-screw continuous mixers, twin-roll mixers, Ross mixers, Hobart mixers, dental mixers, planetary mixers, kneader mixers, and Henschel mixers.

[0129] [Encapsulant, Hot Melt Adhesive] The present invention also relates to an encapsulant or hot melt adhesive for semiconductors that uses the hot melt curable silicone composition of the present invention. The shape of the encapsulant or hot melt adhesive of the present invention is not particularly limited, but is preferably in the form of a film or sheet, and can be provided as an encapsulant film or laminate film for semiconductor encapsulation. The semiconductors that can be encapsulated with the encapsulant of the present invention are not particularly limited, and examples include semiconductors such as SiC and GaN, particularly power semiconductors or optical semiconductors such as light-emitting diodes.

[0130] [Optical Semiconductor Element] The present invention also relates to an optical semiconductor element comprising the encapsulant of the present invention. Examples of optical semiconductor elements include light-emitting diodes (LEDs), semiconductor lasers, photodiodes, phototransistors, solid-state imaging devices, and light emitters and photodetectors for photocouplers, with light-emitting diodes (LEDs) being particularly preferred.

[0131] Because light-emitting diodes (LEDs) emit light from the top, bottom, left, and right of the optical semiconductor element, components that make up the LED should not absorb light, and materials with high light transmittance or high reflectance are preferred. Therefore, the substrate on which the optical semiconductor element is mounted should also be made of a material with high light transmittance or high reflectance. Examples of substrates on which such optical semiconductor elements can be mounted include conductive metals such as silver, gold, and copper; non-conductive metals such as aluminum and nickel; thermoplastic resins containing white pigments such as PPA and LCP; thermosetting resins containing white pigments such as epoxy resin, BT resin, polyimide resin, and silicone resin; and ceramics such as alumina and alumina nitride.

[0132] Specific embodiments of the present invention will be described below. Aspect 1: A hot-melt curable silicone composition comprising: (A-1) an MQ resin-like alkenyl-group-containing organopolysiloxane that is solid at room temperature and contains at least one alkenyl group per molecule; (A-2) a linear alkenyl-group-containing organopolysiloxane that contains at least two alkenyl groups per molecule; (B-1) a linear organohydrogenpolysiloxane that has silicon-bonded hydrogen atoms at both molecular chain terminals; and (C) a curing catalyst, wherein: (i) the content of component (B-1) is 60 mass% or more, based on the total mass of the organohydrogenpolysiloxane components having silicon-bonded hydrogen atoms; (ii) the amount of aryl groups in all silicon-bonded organic groups in all organopolysiloxane components is 10 mol% or less; (iii) the content of component (A-1) is 65 mass% or more, based on the combined mass of components (A-1) and (A-2); (iv) A hot-melt curable silicone composition in which the content of linear organohydrogenpolysiloxanes having silicon-bonded hydrogen atoms only in side chains of the molecular chain is 3 mass % or less, based on the total mass of organohydrogenpolysiloxane components having silicon-bonded hydrogen atoms. Aspect 2: (A-1) The MQ resinous alkenyl-containing organopolysiloxane is represented by the following average unit formula (I-2): Average unit formula (I): (R 2 3SiO 1 / 2 ) s1 (R 2 2nd Round 3 SiO 1 / 2 ) s2 (SiO 4 / 2 ) t (XO 1 / 2 ) u (In the formula, R 2 are the same or different monovalent hydrocarbon groups other than halogen-substituted or unsubstituted alkenyl groups, and R 3is an alkenyl group, 0 < s1 < 1, 0 < s2 < 1, 0 < t < 1, 0 ≦ u < 0.4, and s1 + s2 + t = 1, where u represents the number of (XO) groups (the ratio of the number of (XO) groups to the total number of silicon atoms), assuming that the total number of silicon atoms is 1. Aspect 3: The hot-melt curable silicone composition according to Aspect 1 or 2, wherein the content of (A-1) MQ resinous alkenyl-group-containing organopolysiloxane is typically 40 to 90 mass % based on the total mass of the hot-melt curable silicone composition of the present invention. Aspect 4: The hot-melt curable silicone composition according to any one of Aspects 1 to 3, wherein (A-2) linear alkenyl-group-containing organopolysiloxane is a linear organopolysiloxane capped at both molecular chain terminals with alkenyl groups. Aspect 5: The hot-melt curable silicone composition of any one of Aspects 1 to 4, wherein the (B-1) linear organohydrogenpolysiloxane contains 1 to 100 siloxane units. Aspect 6: The hot-melt curable silicone composition of any one of Aspects 1 to 5, further comprising (B-2) an organohydrogenpolysiloxane consisting solely of M units and Q units, and having at least two silicon-bonded hydrogen atoms per molecule. Aspect 7: The hot-melt curable silicone composition of any one of Aspects 1 to 6, wherein the content of (B-2) the organohydrogenpolysiloxane consisting solely of M units and Q units is 40 mass% or less, based on the total mass of all organohydrogenpolysiloxane components. Aspect 8: The hot-melt curable silicone composition according to any one of Aspects 1 to 7, wherein the molar ratio (H / Ak) of silicon-bonded alkenyl groups to silicon-bonded hydrogen atoms contained in the total organopolysiloxane component is less than 1.2. Aspect 9: An encapsulant or hot-melt adhesive comprising the hot-melt curable silicone composition according to any one of Aspects 1 to 8. Aspect 10: An optical semiconductor device encapsulated with the encapsulant according to Aspect 9.

[0133] The hot-melt curable silicone composition of the present invention will be described in more detail below with reference to the following examples and comparative examples.

[0134] Hot-melt curable silicone compositions were prepared by mixing the components in the amounts (parts by mass) shown in the table. Hereinafter, Me represents a methyl group, Vi represents a vinyl group, Ph represents a phenyl group, and Ep represents a 3-glycidoxypropyl group. The structures of the organopolysiloxane components are shown in simplified form in the table, with the organic groups other than Me in the M, D, T, or Q units indicated in parentheses. The H / Vi ratio indicates the molar ratio of silicon-bonded hydrogen atoms (H) to vinyl groups (Vi) in the organopolysiloxane component. The "total aryl group content" indicates the amount (mol %) of aryl groups in all silicon-bonded organic groups in the entire organopolysiloxane component. Furthermore, (B-1) / (B) represents the ratio of the mass of component (B-1) to the total mass of all organohydrogenpolysiloxane components, and (A-1) / ((A-1)+(A-2)) represents the ratio of the mass of component (A-1) to the total mass of components (A-1) and (A-2).

[0135] Component a-1-1: Average unit formula (Me3SiO 1 / 2 ) 46 (Me2ViSiO 1 / 2 )5(SiO 4 / 2 ) 49 Alkenyl group-containing MQ resin represented by (OH)6, solid at room temperature. Molecular weight: 2800. Component a-1-2: Average unit formula (Me3SiO 1 / 2 ) 41 (Me2ViSiO 1 / 2 )7(SiO 4 / 2 ) 52 Alkenyl-containing MQ resin represented by (OH)5, solid at room temperature. Molecular weight: 2800. Component a'-1: Average unit formula (Me3SiO 1 / 2 ) 30 (Me2ViSiO 1 / 2 )5(MeSiO 3 / 2 ) 65 Alkenyl group-containing MT resin (viscosity at 25°C: 474 mPa·s) Component a-2-1: Average structural formula Me2ViSiO(Me2SiO) 1040Component a-2-2: Average structural formula Me2ViSiO(Me2SiO) Linear alkenyl group-containing organopolysiloxane represented by SiMe2Vi (viscosity at 25°C: 50,000 mPa·s) 235 Component a-2-3: Average structural formula Me2ViSiO(Me2SiO) Linear alkenyl group-containing organopolysiloxane represented by SiMe2Vi (viscosity at 25°C: 1,000 mPa·s) 730 Component a-2-4: Average structural formula Me2ViSiO(Me2SiO) Linear alkenyl group-containing organopolysiloxane represented by SiMe2Vi (viscosity at 25°C: 1,0000 mPa·s) 70 Component a-3: A linear alkenyl group-containing organopolysiloxane represented by the average structural formula (ViMeSiO)4 (viscosity at 25°C: 60 mPa·s) Component a-4-1: A cyclic alkenyl group-containing organopolysiloxane represented by the average structural formula (MeSiO)4 1 / 2 ) 25 (Me2ViSiO 1 / 2 ) 37 (SiO 4 / 2 ) 38 Alkenyl group-containing MQ resin represented by (OH)4, liquid at room temperature, molecular weight 1500, component a-4-2: average unit formula (Me3SiO 1 / 2 ) 45 (Me2ViSiO 1 / 2 ) 15 (SiO 4 / 2 ) 40 Alkenyl group-containing MQ resin represented by (OH)8, liquid at room temperature, molecular weight 1000, component a-4-3: average structural formula (ViMe2SiO 1 / 2 )4(SiO 4 / 2 ) MQ resin-type organopolysiloxane that is liquid at room temperature. Component b-1-1: Average structural formula HMe2SiO(Me2SiO) 20Component b-1-2: Linear organohydrogenpolysiloxane represented by the average structural formula HMe2SiO(Ph2SiO)SiHMe2 Component b-1-3: Linear organohydrogenpolysiloxane represented by the average structural formula HMe2SiO(Me2SiO)7SiHMe2 Component b-1-4: Average structural formula HMe2SiO(Me2SiO) 50 Linear organohydrogenpolysiloxane represented by SiHMe2 Component b'-1: Average structural formula Me3SiO(HMeSiO) 52 Linear organohydrogenpolysiloxane represented by SiMe3 Component b-2-1: Average unit formula M(H) 61 Q 39 Organohydrogenpolysiloxane with a molecular weight of 1600, component b-2-2: average unit formula (HMe2SiO)9(Me3SiO) 46 (SiO 4 / 2 ) 45 The ratio of M(H) to Q is 1.2, the SiH concentration is 0.12 mass%, and the viscosity is 170 mPas. Component c: A platinum / divinyltetramethyldisiloxane complex with a platinum concentration of 3.0 mass%. Component d: Methyl-tris(1,1-dimethylpropynyloxy)silane CH3-Si-(OC(CH3)2-C≡CH)3. Component e: 1-ethynyl-1-cyclohexanol. Component f: Bis(2-ethylhexyl) maleate.

[0136] [Evaluation] (Curability) The obtained curable silicone compositions were heat treated for 2 hours at 120° C. Compositions that gave completely cured products were rated as "OK."

[0137] (Light Transmittance) The obtained curable silicone composition was placed between two transparent glass plates and cured by heating at 120°C for 2 hours to prepare a test specimen with an optical path length of 1 mm. The light transmittance of this test specimen for light with a wavelength of 450 nm was measured at 25°C. A light transmittance of more than 90% was rated as OK, and a light transmittance of 90% or less was rated as NG.

[0138] (Hot Melt Properties) The resulting curable silicone composition was coated onto a release film to a thickness of 0.3 mm and semi-cured in an oven at an appropriate temperature and time (70-100°C for 30 minutes) to obtain a B-stage film. Films in the B-stage that were solid at room temperature and had a minimum G' value (Pa) of 10,000 or less were deemed acceptable. The storage modulus (G') of the film in the B-stage was measured at 25°C and an ambient pressure of 1013 mbar using an Anton Paar rheometer model MCR302, a rheometer equipped with viscoelasticity measurement capabilities.

[0139] The results are shown in the table below.

[0140]

[0141]

[0142]

[0143]

[0144] As can be seen from the above results, the curable silicone compositions with low aryl group content according to the present invention in the examples exhibited hot-melt properties and cured at low temperatures in a short time, and were able to form cured products with excellent transparency.

[0145] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Addition, omission, substitution, and other modifications of the configuration are possible within the scope of the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the scope of the appended claims.

Claims

1. A hot-melt curable silicone composition comprising: (A-1) an MQ resin-like alkenyl-group-containing organopolysiloxane that is solid at room temperature and contains at least one alkenyl group per molecule; (A-2) a linear alkenyl-group-containing organopolysiloxane that contains at least two alkenyl groups per molecule; (B-1) a linear organohydrogenpolysiloxane that has silicon-bonded hydrogen atoms at both molecular chain terminals; and (C) a curing catalyst, wherein: (i) the content of component (B-1) is 60 mass% or more, based on the total mass of the organohydrogenpolysiloxane components that contain silicon-bonded hydrogen atoms; (ii) the amount of aryl groups in all silicon-bonded organic groups in all organopolysiloxane components is 10 mol% or less; (iii) the content of component (A-1) is 65 mass% or more, based on the combined mass of components (A-1) and (A-2); (iv) A hot-melt curable silicone composition in which the content of linear organohydrogenpolysiloxane having silicon-bonded hydrogen atoms only in side chains of the molecular chain is 3 mass% or less, based on the total mass of organohydrogenpolysiloxane components having silicon-bonded hydrogen atoms.

2. (A-1) MQ resin-like alkenyl group-containing organopolysiloxane is represented by the following average unit formula (I-2): Average unit formula (I): (R 2 3SiO 1 / 2 ) s1 (R 2 2nd Round 3 SiO 1 / 2 ) s2 (SiO 4 / 2 ) t (XO 1 / 2 ) u (In the formula, R 2 are the same or different monovalent hydrocarbon groups other than halogen-substituted or unsubstituted alkenyl groups, and R 3 is an alkenyl group, 0 < s1 < 1, 0 < s2 < 1, 0 < t < 1, 0 ≦ u < 0.4, and s1 + s2 + t = 1, and u represents the number of (XO) groups (the ratio of the number of (XO) groups to the total number of silicon atoms) when the total number of silicon atoms is taken as 1.

3. The hot-melt curable silicone composition according to claim 1, wherein the content of (A-1) MQ resinous alkenyl group-containing organopolysiloxane is 40 to 90 mass % based on the total mass of the hot-melt curable silicone composition.

4. The hot-melt curable silicone composition according to claim 1, wherein (A-2) the linear alkenyl-containing organopolysiloxane is a linear organopolysiloxane capped at both molecular chain terminals with alkenyl groups.

5. The hot-melt curable silicone composition according to claim 1, wherein the linear organohydrogenpolysiloxane (B-1) contains 1 to 100 siloxane units.

6. The hot-melt curable silicone composition according to claim 1, further comprising (B-2) an organohydrogenpolysiloxane consisting solely of M units and Q units and having at least two silicon-bonded hydrogen atoms per molecule.

7. The hot-melt curable silicone composition according to claim 6, wherein the content of (B-2) organohydrogenpolysiloxane consisting only of M units and Q units is 40 mass% or less based on the total mass of all organohydrogenpolysiloxane components.

8. The hot-melt curable silicone composition according to claim 1, wherein the molar ratio (H / Ak) of silicon-bonded alkenyl groups to silicon-bonded hydrogen atoms contained in the entire organopolysiloxane component is less than 1.

2.

9. A sealant or hot melt adhesive comprising the hot melt curable silicone composition according to any one of claims 1 to 8.

10. An optical semiconductor device encapsulated with the encapsulant according to claim 9.

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