Organopolysiloxane composition, cured product thereof, sealant for electronic components, electronic components, and method for protecting semiconductor chips

Abstract

To provide a curable organopolysiloxane composition which enables production of a cured product that has low elastic modulus and low stress, excellent in strength, cold resistance and transparency, maintains the above features under a long-time high-temperature condition by addition of a cerium compound, and prevents cracking and peeling even when a strong temperature gradient occurs inside.SOLUTION: A hydrosilylated curable organopolysiloxane composition contains organopolysiloxane and organohydrogenpolysiloxane which are crosslinked by hydrosilylation reaction, a non-reactive organopolysiloxane resin having a mass reduction ratio when being exposed at 200°C for 1 hour of 2.0 mass% or less, and arbitrarily contains a reaction product of alkali metal silanolate, and at least one or more kinds of cerium chlorides and / or carboxylates.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an organopolysiloxane composition that cures to give a cured product that exhibits excellent transparency and strength, and further relates to an organopolysiloxane composition that, due to the addition of specific additives, gives an organopolysiloxane cured product that exhibits excellent heat resistance, particularly crack resistance, even when temperature differences occur inside components at high temperatures. The present invention also relates to an electronic component sealant containing the organopolysiloxane composition and an electronic component equipped with the organopolysiloxane cured product. [Background technology]

[0002] Curable organopolysiloxane compositions contain an organopolysiloxane as a base component, in which siloxane units are polymerized, and react with a crosslinking agent or the like to form a cured organopolysiloxane. Among curable organopolysiloxane compositions, those that cure via a hydrosilylation reaction generally contain an organopolysiloxane having an alkenyl group, such as a vinyl group, bonded to a silicon atom, an organohydrogenpolysiloxane having a hydrogen atom (also known as an SiH group) bonded to a silicon atom, and a hydrosilylation catalyst, and are cured via an addition reaction between the SiH group and the alkenyl group (see, for example, Patent Documents 1 to 4). The crosslink density of the cured product of a curable organopolysiloxane composition can be designed by adjusting the ratio of SiH groups to alkenyl groups, etc., and desirable physical and chemical properties can be imparted to the cured product. In particular, many low-crosslink density organopolysiloxane cured products known as "silicone gels" have excellent heat resistance, weather resistance, oil resistance, cold resistance, and electrical insulation properties, as well as a low modulus of elasticity and low stress. Taking advantage of these low modulus of elasticity and low stress, characteristics not found in other materials such as various elastomers, cured organopolysiloxane gel products are used as sealants to protect electronic components such as in-vehicle electronic components, consumer electronic components, and display components, or for bonding components. In recent years, demands for higher reliability in these components have led to a demand for organopolysiloxane materials, including cured organopolysiloxane gel products, with greater strength. In particular, in-vehicle components such as displays and small cameras for outdoor sports are exposed to strong or continuous vibrations, and therefore require strong bonded joints.

[0003] Furthermore, depending on the application, cured organopolysiloxane products are required to have greater cold resistance and heat resistance than ever before, and improved reliability, including physical strength, across a wide temperature range is desired. For example, with the recent widespread use of power devices, electronic components that operate under high voltages and currents for power control and conversion, the operating temperatures of these electronic components, particularly silicon chips, have risen from the conventional 150°C to approximately 175°C. Furthermore, with the widespread use of SiC semiconductors, operating temperatures of 200°C or higher are increasingly required. For this reason, methods have been proposed for improving the heat resistance of cured organopolysiloxane gels used as protective materials for these devices by adding various heat-resistant additives (e.g., Patent Documents 4 to 7). Some cured organopolysiloxane products obtained by curing organopolysiloxane compositions containing these heat-resistant additives exhibit sufficient heat resistance to maintain their low elastic modulus even when exposed to temperatures exceeding 200°C for extended periods of time.

[0004] However, ensuring the reliability of power devices requires more than just high heat resistance for the organopolysiloxane cured material used. Power semiconductor modules used in power devices generate heat during operation, with the heat source being the bottom of the module. Depending on the device's shape or structure, only the bottom of the organopolysiloxane cured material used as a protective material may be exposed to high heat, resulting in significant temperature differences within the same component. Such temperature gradients within components generate internal stress as differences in the coefficient of expansion within the organopolysiloxane cured material. This can lead to cracks (fissures and fissures) in the organopolysiloxane cured material, particularly over time and with thermal cycling, deteriorating its protective function. While the organopolysiloxane composition described in Patent Document 4 and elsewhere produces an organopolysiloxane cured material with excellent elastic properties even at temperatures exceeding 200°C, there is still room for improvement in the technical challenge of preventing cracks due to temperature differences within components. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 1978-017847 [Patent Document 2] Japanese Patent Application Publication No. 56-143241 [Patent Document 3] International Publication No. WO2015 / 034029 [Patent Document 4] Japanese Patent Application Publication No. 08-225743 [Patent Document 5] International Publication No. WO2015 / 111409 [Patent Document 6] Japanese Patent Application Publication No. 2018-053015 [Patent Document 7] Patent Publication No. 2021-011510 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention was made in consideration of the above circumstances and aims to solve problems related to the storage, preservation, and reliability of electronic component sealants comprising organopolysiloxane compositions and bonding members for electronic components comprising cured products of the organopolysiloxane compositions. Another object of the present invention is to improve the performance of organopolysiloxane cured products obtained by curing organopolysiloxane compositions, i.e., to overcome the problems that conventional organopolysiloxane cured products have insufficient strength, deterioration in elastic modulus, stress, and transparency after long-term use at high temperatures, and the tendency for cracks to occur within the organopolysiloxane cured product when large temperature differences occur within the component. Another object of the present invention is to improve the reliability and continuous use life of electronic components due to insufficient strength and heat resistance of organopolysiloxane cured products used in electronic components, as well as their deterioration. [Means for solving the problem]

[0007] After extensive research, the present inventors have found that the above-mentioned problems can be solved by preparing a hydrosilylation-curable organopolysiloxane composition containing an organopolysiloxane resin that does not contain low-molecular-weight siloxane oligomers, has a certain amount of branched siloxane units, and does not contain alkenyl groups, and then using the cured product of the composition. Specifically, the present inventors have discovered that a hydrosilylation-curable organopolysiloxane composition containing (A) an organopolysiloxane having a viscosity at 25°C in the range of 10 to 10,000 mPa·s and containing an average of at least two silicon-bonded alkenyl groups per molecule, and (B) a polymer having the general formula (A), which exhibits a mass loss of 2.0% or less when exposed to 200°C for 1 hour, is (R 1 3SiO 1 / 2 ) a (SiO 4 / 2 ) b (R 2 O 1 / 2 ) c (In the formula, each R 1 are independently monovalent hydrocarbon groups having 1 to 10 carbon atoms and no carbon-carbon double bonds; R 2The inventors have discovered that the problems related to mechanical strength and adhesive strength can be solved by using a curable organopolysiloxane composition containing: (a) an organopolysiloxane resin represented by the formula: a, b, and c; (b) a, b, and c are each a hydrogen atom or an alkyl group having 1 to 10 carbon atoms; and (c) a, b, and c satisfy the conditions 0.35≦a≦0.55, 0.45≦b≦0.65, 0≦c≦0.05, and a+b=1; (C) a branched organohydrogenpolysiloxane having a viscosity at 25°C in the range of 2 to 10,000 mPa s and having at least two silicon-bonded hydrogen atoms per molecule; and (D) a catalyst for hydrosilylation curing. They have also discovered that the problems related to heat resistance and cracking can be solved by adding (E) a specific amount of the reaction product of (e1) an alkali metal silanol compound and (e2) a cerium chloride salt or a cerium carboxylate salt, thereby completing the present invention. The present inventors also found that the above problems can be solved by an electronic component sealant or laminating agent comprising the organopolysiloxane composition, an organopolysiloxane cured product obtained by curing the organopolysiloxane composition, a laminating member comprising the cured product, and an electronic component equipped with any of these, thereby completing the present invention.

[0008] More specifically, the organopolysiloxane composition of the present invention contains, per 100 parts by mass of component (A), 10 to 80 parts by mass of component (B), component (C) in an amount such that there are 0.5 to 2.0 silicon-bonded hydrogen atoms per silicon-bonded alkenyl group in the entire composition, and component (D) in a catalytic amount sufficient to react and cure (A) to (C). Furthermore, when heat resistance is required, the composition contains 0 to 10.0 parts by mass of component (E). Component (E) may contain 0.5 to 5.0 mass% of cerium atoms, and when added, the amount may be such that the cerium content of component (E) is 0.005 to 0.15 mass% of the entire organopolysiloxane composition.

[0009] Furthermore, the components (A) and (C) may be branched, straight-chain, or a mixture thereof.

[0010] The present invention further provides an electronic component sealant, particularly a sealant for power devices, containing the organopolysiloxane composition. The sealant may be substantially transparent. The present invention also provides a bonding member for electronic components containing the organopolysiloxane composition.

[0011] The organopolysiloxane composition of the present invention is curable, and a cured product is obtained by a hydrosilylation reaction. The present invention provides this organopolysiloxane cured product. The organopolysiloxane cured product of the present invention is substantially transparent, and immediately after completion of the curing reaction, the direct reading of 1 / 4 consistency as specified in JIS K2220 is within the range of 10 to 150. In the case of a cured product of the present invention containing component (E) and having improved heat resistance, even after being held at 225°C for 1,000 hours, it maintains 50% or more of the direct reading of 1 / 4 consistency immediately after completion of the curing reaction. The organopolysiloxane cured product of the present invention can be used to protect electronic components and maintain bonding. The organopolysiloxane cured product of the present invention may be substantially transparent.

[0012] The organopolysiloxane composition of the present invention and its encapsulant or laminating member can be placed in contact with or near an electronic component such as a semiconductor, cured by heating, and then placed in place. Therefore, the present invention provides an electronic component equipped with such a cured organopolysiloxane. Furthermore, if the electronic component is an optical component or optoelectronic component such as a light-emitting diode, the present invention provides a general lighting fixture, optical component, or optoelectronic component equipped with the cured organopolysiloxane. In particular, the present invention provides a semiconductor chip for use in harsh environments, equipped with the cured organopolysiloxane containing component (E), and a device equipped with the same. The semiconductor chip includes light-emitting semiconductor elements such as LEDs and power semiconductors, and the present invention provides a power device with excellent heat and cold resistance.

[0013] Furthermore, the present invention provides a method for protecting semiconductor chips using the organopolysiloxane composition and the cured product thereof, and also provides applications in particular where heat resistance and cold resistance are required. [Effects of the Invention]

[0014] The organopolysiloxane composition of the present invention is characterized by its excellent intrinsic gel strength after curing, and by its ability to produce cured products that exhibit reduced lot-to-lot variation in gel hardness measured by penetration, which is generally difficult to achieve. Furthermore, by adding a cerium-containing component to this composition, it is possible to obtain organopolysiloxane cured products that exhibit excellent heat resistance and transparency at temperatures exceeding 200°C, maintain a low modulus of elasticity, low stress, and high transparency even after long-term use at high temperatures, and are resistant to cracking even when large temperature differences occur within the component over long periods of time, as occurs when a high-temperature heat source is placed only on the bottom surface of the cured product. Furthermore, the present invention provides an electronic component sealant comprising this composition and electronic components equipped with the organopolysiloxane cured product.

[0015] The organopolysiloxane cured product of the present invention has superior strength to conventional organopolysiloxane cured products. When used as a sealant or bonding material for electronic components such as automotive electronic components, consumer electronic components, and display components, it can protect these components for longer periods and improve their reliability. Furthermore, when the heat-resistant organopolysiloxane cured product of the present invention is used to protect electronic components such as ICs and hybrid ICs, it maintains transparency even at high temperatures of 200°C or higher, as required for SiC semiconductors, and has excellent strength, heat resistance, and cold resistance, which can be expected to improve long-term durability. Furthermore, even under conditions where large temperature differences occur within the organopolysiloxane cured product due to the placement of a heat source, or in extreme environments such as outer space where it is exposed to extreme or partial temperature changes, it is less likely to develop problems such as cracking or to deteriorate over time. Therefore, electronic components with high reliability and durability can be provided even under such conditions. DETAILED DESCRIPTION OF THE INVENTION

[0016] Each component will be described in detail below. In this specification, the siloxane unit is classified into M units (ASiO 1 / 2 ), D units (A2SiO 2 / 2 ), T units (ASiO 3 / 2 ), Q units (SiO 4 / 2 ), where A is a group or atom other than -OSi. The viscosity is measured at 25°C using a B-type viscometer in accordance with JIS K7117-1.

[0017] [Curable organopolysiloxane composition] (A) Organopolysiloxane having alkenyl groups Component (A) is an alkenyl-containing organopolysiloxane and is one of the main components (base polymers) of the organopolysiloxane composition of the present invention. This organopolysiloxane contains an average of at least two silicon-bonded alkenyl groups (hereinafter also referred to as "silicon-bonded alkenyl groups") per molecule and has a viscosity of 10 to 10,000 mPa·s at 25°C. More specifically, component (A) is either component (A-1) or (A-2) below, or a mixture thereof, and may further optionally contain an alkenyl-containing organopolysiloxane resin as component (A-3). Component (A-1) can impart cold resistance to the organopolysiloxane cured product, and component (A-2) can improve the strength of the organopolysiloxane cured product. Component (A-1) and component (A-2) can be combined depending on the desired properties. Furthermore, it is possible to improve cold resistance by combining with component (B) described below, and these combinations are also described below.

[0018] Component (A-1) is a branched organopolysiloxane containing an average of at least two silicon-bonded alkenyl groups per molecule. Component (A-1) contains a certain amount of RSiO 3 / 2 (wherein R is a monovalent hydrocarbon group) The component (A-1) may have a branched structure with units. The component (A-1) can preferably be represented by the following average structural formula (1): (R3SiO 1 / 2 ) d (R2SiO 2 / 2 ) e (RSiO 3 / 2 ) f (1) In formula 1, R represents a monovalent hydrocarbon group, and d, e, and f are each positive numbers satisfying 0.1≦d≦10.0, 80.0≦e≦99.8, 0.1≦f≦10.0, and d+e+f=1. The degree of polymerization (DP) of component (A-1) is preferably 200 or less.

[0019] The branched organopolysiloxane of component (A-1) has a specific amount of branched structure. Specifically, of all the siloxane units constituting component (A-1), RSiO 1 / 2 The unit is 0.1 or more, 1.0 or more, or 3.0 or more, and at the same time 10.0 or less, in mole percent, and RSiO 2 / 2 The unit is 80.0 or more by mole and 99.8 or less, 98.9 or less, or 96.9 or less by mole percent, RSiO 3 / 2 The unit is 0.1 or more, 1.0 or more, or 3.0 or more, and at the same time 10.0 or less, in mole percent. That is, the ratio of d:e:f in formula 1 corresponds to the ratio of these mole percents. By having such a branched structure in component (A-1), it is possible to obtain an organopolysiloxane cured product that has excellent cold resistance, especially at low temperatures. Note that the above-mentioned R2SiO 2 / 2 Units and RSiO 3 / 2 Units and R3SiO 1 / 2 The molar ratio of units is a value determined by measurement using nuclear magnetic resonance (NMR).

[0020] In component (A-1), the monovalent hydrocarbon group bonded to a silicon atom in the siloxane structural unit (i.e., the R described above) is located in a side chain of the main chain or branched chain, or at the terminal, and is either i) a monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond and is unsubstituted or contains a substituent, or ii) a monovalent alkenyl group. Component (A-1) has an average of at least two alkenyl groups bonded to a silicon atom per molecule.

[0021] When R is i) a monovalent hydrocarbon group containing no aliphatic unsaturated bonds and unsubstituted or substituted, the number of carbon atoms may be 1 or more and any integer within the range of 2 or less, 3 or less, 4 or less, 6 or less, 8 or less, 9 or less, or 10 or less. The number of carbon atoms in R is preferably within the range of 1 to 6. Specific examples of the monovalent hydrocarbon group containing no aliphatic unsaturated bonds and unsubstituted or substituted include alkyl groups, aryl groups, and aralkyl groups; among these, methyl groups, ethyl groups, phenyl groups, and benzyl groups are particularly preferred, with methyl groups and phenyl groups being particularly preferred due to their ease of synthesis. Other examples include groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms such as chlorine, bromine, or fluorine, such as chloromethyl groups and 3,3,3-trifluoropropyl groups.

[0022] When R is ii) a monovalent alkenyl group, the alkenyl group has 2 or more carbon atoms and may be any integer within the range of 3 or less, 4 or less, or 6 or less, and is an alkenyl group having 2 to 4 or 2 to 3 carbon atoms. Specific examples thereof include a vinyl group, an allyl group, an isopropenyl group, a butenyl group, an isobutenyl group, etc., and a vinyl group is particularly exemplified.

[0023] In the average structural formula (1) of component (A-1), the proportion of silicon-bonded alkenyl groups among all the monovalent hydrocarbon groups R bonded to silicon atoms may be 0.10 or more, 0.25 or more, or 0.50 or more by mole, and may also be 4.00 or less by mole, or 2.00 by mole. The amount of alkenyl groups is a value determined using a Fourier transform near-infrared spectrometer.

[0024] The viscosity of component (A-1) at 25°C is in the range of 10 to 10,000 mPa·s, but may also be in the range of 10 to 5,000 mPa·s or 10 to 1,000 mPa·s at 25°C.

[0025] The branched organopolysiloxane (A-1) can be synthesized with the desired viscosity and design structure by known methods. For example, RSiO 3 / 2 , R2SiO 2 / 2 , and RSiO 1 / 2 and a hydrolyzate having each of the siloxane units of ViR 0 2SiOSiR 0 2Vi and cyclic polysiloxane (R 0 2SiO) y (In each formula, R is a monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, such as an alkyl group, and Vi is an alkenyl group, such as a vinyl group) can be prepared by heating and equilibrating the resulting compound in the presence of potassium silanolate.

[0026] When component (A-1) contains the above amount of silicon-bonded alkenyl groups, it is possible to obtain, after completion of curing, a flexible, so-called gel-like cured organopolysiloxane product having a direct reading of 1 / 4 consistency as specified in JIS K 2220 within the range of 10 to 150. In the present invention, "completion of curing" refers to the curable organopolysiloxane composition being allowed to stand at 80°C for one hour.

[0027] The viscosity of component (A-1) contributes to improving the handling and flowability of the organopolysiloxane composition of the present invention, as well as the strength of the resulting cured product. Here, the strength of a cured product refers to the degree to which the cured product can withstand stress without breaking. In other words, the greater the stress that causes the cured product to break, the stronger the cured product. In the present invention, this is measured using a method similar to that used to measure adhesive strength. That is, when cohesive failure occurs without peeling during adhesive strength measurement, the cured product itself is destroyed and the measurement is terminated. Therefore, the strength of the organopolysiloxane cured product in question is expressed as the numerical value of the stress at which cohesive failure occurs in the adhesive strength test.

[0028] By using component (A-1), the organopolysiloxane composition of the present invention can provide an organopolysiloxane cured product that not only has the strength described above, but also has excellent cold resistance, even at temperatures below -40°C.

[0029] Component (A-2) is a linear organopolysiloxane containing, on average, at least two silicon-bonded alkenyl groups per molecule. Component (A-2) can preferably be represented by the following average structural formula (2): (R3SiO 1 / 2 ) g (R2SiO 2 / 2 ) h (2) (In formula (2), R represents a monovalent hydrocarbon group similar to R in general formula (1) of component (A-1) described above, and is i) an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, or ii) a monovalent alkenyl group. g and h each represent a positive number, where 0.1≦g≦10.0, 90.0≦h≦99.9, and g+h=1.) The degree of polymerization of component (A-2) is a number that is 100 or more, 150 or more, or 200 or more, and simultaneously 300 or less, 400 or less, or 500 or less.

[0030] Of all the siloxane units that make up component (A-2), RSiO 1 / 2 The amount is in the range of 0.1 or more, 0.5 or more, or 1.0 or more, and at the same time 10.0 or less, 5.0 or less, or 3.0 or less, in mole percent, RSiO 2 / 2 The remaining units are 90.0 or more, 95.0 or more, or 97.0 or more in mole percent, and simultaneously 99.9 or less, 99.5 or less, or 99.0 or less in mole percent. Here, the ratio of g:h in Formula 2 corresponds to the ratio of these mole percents. 2 / 2 Units and RSiO 1 / 2 The molar ratio of units can be determined by measuring by nuclear magnetic resonance (NMR).

[0031] In the average structural formula (2) of component (A-2), the proportion of silicon-bonded alkenyl groups among all the monovalent hydrocarbon groups R bonded to silicon atoms may be, in mole percent, at least 0.25, at least 0.50, or at least 1.00, and at the same time at most 4.00, at most 3.00, or at most 2.00. The amount of alkenyl groups can be quantified using a Fourier transform near-infrared spectrometer.

[0032] The viscosity of component (A-2) at 25°C is in the range of 10 to 10,000 mPa·s, but it may be 1.0 or more, or 5.0 or more, or may be 5000 or less, or 1000 or less, at 25°C.

[0033] When component (A-2) has the above structure, it is possible to obtain a flexible, so-called gel-like organopolysiloxane cured product after curing, whose direct reading of 1 / 4 consistency as specified in JIS K 2220 is in the range of 10 to 150. By having this viscosity, component (A-2) contributes to improving the handling and flowability of the organopolysiloxane composition of the present invention, as well as the strength of the resulting cured product.

[0034] Examples of linear organopolysiloxanes represented by the above average structural formula (2) include polymers of dimethylsiloxane, but further examples include polymers of methyltrifluoropropylsiloxane, copolymers containing methylvinylsiloxane and / or diphenylsiloxane-phenylmethylsiloxane in any ratio in addition to dimethylsiloxane and / or methyltrifluoropropylsiloxane, and also polymers in which both ends of these polymers are capped with dimethylvinylsiloxy groups, methyldivinylsiloxy groups, or trivinylsiloxy groups, or one end is capped with trimethylsiloxy groups and the other end with dimethylvinylsiloxy groups; copolymers containing vinylmethylsiloxane, both ends of which are capped with trimethylsiloxy groups, and dimethylpolysiloxane and / or methyltrifluoropropylpolysiloxane in any ratio, and optionally further containing diphenylsiloxane or phenylmethylsiloxane; and the like.

[0035] Among the linear organopolysiloxanes exemplified above, those that do not contain phenyl groups (i.e., dimethylpolysiloxanes) are effective in improving the mechanical strength of the cured product obtained by curing the organopolysiloxane composition of the present invention, but they are unable to impart cold resistance like the aforementioned component (A-1). In contrast, phenyl-containing copolymers (i.e., phenyl-containing organopolysiloxanes), such as dimethylvinylsiloxy-terminated dimethylsiloxane-diphenylsiloxane copolymers, contribute to cold resistance. Therefore, if cold resistance is not required, component (A-2) containing only dimethylpolysiloxane without component (A-1) can be used as component (A). However, to achieve both cold resistance and mechanical strength, it is necessary to use component (A-1) in combination with component (A-2) and / or to use a phenyl-containing polysiloxane as component (A-2). In this case, cold resistance can be imparted to the resulting cured product by controlling the phenyl group content in the composition to the amount described below.

[0036] Regardless of whether (A-1) or (A-2) is used, when a phenyl-containing organopolysiloxane is used as part or all of component (A), the phenyl group content, relative to the total silicon-bonded functional groups, should be 1 or more or 3 or more mol % and 10 or less or 7 or less. This is because if the phenyl group content exceeds 10 mol %, the phenyl groups in the cured product may increase the hardness of the organopolysiloxane cured product, reducing its flexibility. Depending on the amount of phenyl groups added, it may be difficult to form a gel-like cured product with the low hardness required for stress relaxation properties. Furthermore, if the phenyl group content is less than the lower limit of 1 mol %, sufficient cold resistance may not be imparted to the cured product of an organopolysiloxane having a dimethylpolysiloxane skeleton.

[0037] Regardless of whether it is component (A-1) or component (A-2), the mechanical strength of the organopolysiloxane cured product of the present invention can be improved by adding the above-mentioned so-called dimethylpolysiloxane to the above-mentioned so-called phenyl group-containing organopolysiloxane as the main component. Even in this case, the phenyl group content of the curable organopolysiloxane composition is preferably within the range exemplified in the previous paragraph. In particular, if the phenyl group content exceeds the above upper limit, mutual dissolution with the dimethylpolysiloxane used in combination becomes difficult, and the uniformity of the entire composition may be impaired.

[0038] As mentioned above, the quantitative relationship between component (A-1) and component (A-2) may be such that each component can be used alone or in combination, but from the viewpoint of achieving both cold resistance and mechanical strength in the resulting organopolysiloxane cured product, it is preferable to use 2 to 150 parts by mass, or 2 to 100 parts by mass, of the dimethylpolysiloxane-based component (A-2) per 100 parts by mass of component (A-1). By using this quantitative range, the cold resistance and physical properties of the resulting organopolysiloxane cured product can be improved, and the handleability of the organopolysiloxane composition before curing can be further improved, while also being advantageous in terms of cost.

[0039] The optional component (A-3) is an alkenyl group-containing organopolysiloxane resin, which is a resinous organopolysiloxane component having a three-dimensional branched structure. Component (A-3) contains, on average, at least two alkenyl groups in the molecule, and R r SiO 3 / 2 (In the formula, R r is a monovalent organic group) and siloxane units represented by SiO 4 / 2 The organopolysiloxane resin is one in which the total molar amount of siloxane units selected from the siloxane units represented by R r is a monovalent organic group similar to R in general formula (1) of component (A-1), i.e., i) an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, or ii) a monovalent alkenyl group, or a hydroxyl group.

[0040] The alkenyl groups in component (A-3) are subject to the same descriptions herein as those for the alkenyl groups in component (A-1). Examples of such alkenyl groups include vinyl groups and hexenyl groups. Because alkenyl groups have hydrosilylation reactivity, they are incorporated into the crosslinking reaction that forms the organopolysiloxane cured product, which is expected to improve the mechanical strength of the resulting cured product.

[0041] Examples of groups bonded to silicon atoms in component (A-3) other than alkenyl groups include hydroxyl groups and unsubstituted or substituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated bonds. The number of carbon atoms may be an integer of 1 or more and 2 or less, 3 or less, 4 or less, or 6 or more, or an integer of 6 or more, 7 or more, and 8 or less, 9 or less, 10 or less, 12 or less, 16 or less, 18 or less, or 20 or less. Specific examples of unsubstituted or substituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated bonds include alkyl groups, aryl groups, aralkyl groups, and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as chlorine, bromine, or fluorine, or alkoxy groups in which hydroxyl groups have been substituted. Among these, methyl groups, ethyl groups, phenyl groups, and benzyl groups are particularly preferred, and, due to their ease of synthesis, methyl groups, phenyl groups, and 3,3,3-trifluoropropyl groups are particularly preferred. From the viewpoint of mutual solubility with other components contained in the composition, an alkyl group, particularly a methyl group, is preferred.

[0042] The amount of component (A-3) added is not limited, but can be in the range of greater than 0.0, or greater than 0.10 but less than 10, less than 7.5, or less than 5.0 mass % of the total organopolysiloxane composition of the present invention. By adding component (A-3) in this range, in addition to components (A-1) and (A-2), the mechanical strength of the resulting organopolysiloxane cured product can be improved. The mechanical strength-improving effect of the amount of component (A-3) added can be significantly observed when the amount is 0.10 mass % or greater. Furthermore, if the amount exceeds 10 mass %, the viscosity of the organopolysiloxane composition at 25°C may become too high, and the resulting cured product may become too hard, which is undesirable from a practical standpoint.

[0043] (B) Organopolysiloxane resins that contain a small amount of low-molecular-weight molecular species and do not contain alkenyl groups. Component (B) is one of the main components of the present invention and is an organopolysiloxane resin that does not contain alkenyl groups. 1 3SiO 1 / 2 ) and siloxane units (M units) represented by (SiO 4 / 2 ) is an organopolysiloxane resin known as an MQ resin, which is composed of siloxane units (Q units) represented by the formula: In the present invention, component (B) contains a low content of low-molecular-weight reaction by-products, as will be described later, and therefore exhibits a mass loss of 2.0% by mass or less when exposed to 200°C for 1 hour. This MQ resin is characterized in that it contains a low content of low-molecular-weight reaction by-products.

[0044] The organopolysiloxane resin of component (B) can be specifically represented by the following average structural formula (3): (R 1 3SiO 1 / 2 ) a (SiO 4 / 2 ) b (R 2 O 1 / 2 ) c (3) (wherein a, b, and c are 0.35≦a≦0.55, 0.45≦b≦0.65, 0≦c≦0.05, and a+b=1) In the above average structural formula (3), each R 1 are independent monovalent hydrocarbon groups containing no aliphatic unsaturated bonds, and the number of carbon atoms is 1 or more, and may be any integer within the range of 2 or less, 3 or less, 4 or less, 6 or less, 8 or less, 9 or less, or 10 or less. The structure is a group selected from the group consisting of alkyl groups, aryl groups, and aralkyl groups, and particular examples include methyl groups and phenyl groups. Here, the total number of R in one molecule is 1 70 mol % or more of the R 1 It is noteworthy from the viewpoint of industrial production and the technical effect of the invention that 88 mol % or more of the above are alkyl groups having 1 to 10 carbon atoms, particularly methyl groups.

[0045] In addition, in the above formula (3), R 2 R is a hydrogen atom or an alkyl group, and in the case of an alkyl group, the number of carbon atoms may be 1 or more and may be any integer in the range of 2 or less, 3 or less, 4 or less, 6 or less, 8 or less, 9 or less, or 10 or less. 2 Examples of the alkyl group of R include methyl, ethyl, propyl, butyl, pentyl, and hexyl groups. 2 Group R containing 2 O 1 / 2 corresponds to a hydroxyl group or an alkoxy group, and the oxygen atom thereof is bonded to the silicon atom of the siloxane unit.

[0046] In the above formula (3), a, b, and c are each an M unit R 1 3SiO 1 / 2 Siloxane units, Q units, SiO 4 / 2 Siloxane units represented by R 2 O 1 / 2 This indicates the proportion of hydroxyl groups or alkoxy groups represented by the formula:

[0047] In the above formula (3), a is a number within the range of 0.35 or more, 0.40 or more, or 0.45 or more, and simultaneously 0.60 or less, or 0.55 or less. If a is at or above the lower limit of the above range, it is possible to prevent the viscosity of the composition containing this component from becoming too high. On the other hand, if a is at or below the upper limit of the above range, the mechanical strength (hardness, elongation, etc.) of the organopolysiloxane cured product obtained by curing the curable silicone composition of the present invention will not become too low.

[0048] In the above formula (3), b is a number within the range of 0.40 or more, or 0.45 or more, and simultaneously 0.7 or less, or 0.65 or less. When b is within the above numerical range, the viscosity of the composition containing this component does not become too high, and the cured product obtained by curing the composition can have excellent mechanical strength.

[0049] In the above formula (3), c may be 0, but in any case, it is a number within the range of 0.0 or more and 0.05 or less, or 0.03 or less. When c is equal to or less than the upper limit of the range, compositions containing this component exhibit excellent thermosetting properties.

[0050] Since component (B) is produced by an equilibrium reaction between raw materials that provide the Q units that form the resinous polymer portion and the M units that form its terminal end, the molecular weight of component (B) can be controlled by the ratio of M units to Q units, i.e., the values ​​of a and b above. Within the range of a and b above, the value measured by gel permeation chromatography (GPC) using toluene as a solvent (using polystyrene standard material as the reference) will be in the range of 2,000 to 25,000.

[0051] The MQ resin, the main molecular species of component (B), can be synthesized with the desired molecular weight and design structure by known methods. However, the MQ resin incorporated into the composition of the present invention is characterized by a mass loss of 2.0% by mass or less when exposed to 200°C and atmospheric pressure for 1 hour. The mass loss under these conditions is due to the presence of low-molecular-weight components that volatilize under these conditions. In the production process of component (B), volatile low-molecular-weight components appear as by-products during polymerization of an organopolysiloxane resin composed of M and Q units. These volatile low-molecular-weight components are referred to herein as "M4Q structures." The inclusion of M4Q structures in the organopolysiloxane composition of the present invention significantly reduces the hardness of the cured organopolysiloxane obtained by curing the organopolysiloxane composition. The hardness of the resulting cured organopolysiloxane varies significantly depending on its content, with the change evident in the penetration number, which represents hardness.

[0052] It is known that organopolysiloxane resins containing M4Q structures are depleted and eventually lost when maintained at temperatures above 200°C. This means that when a cured organopolysiloxane containing an organopolysiloxane resin containing M4Q structures is aged at temperatures above 200°C, the M4Q structures gradually volatilize. As volatilization progresses, the penetration of the cured organopolysiloxane decreases significantly, resulting in an increase in hardness. Specifically, MQ resins produced by known methods contain a certain amount of M4Q structures. Therefore, when organopolysiloxane compositions are prepared using existing MQ resins without further purification, the heat resistance of the resulting cured products is poor, especially over time. Furthermore, because the content of M4Q structures typically varies from lot to lot, the use of such MQ resins in curable organopolysiloxane compositions poses a quality stability problem, as the penetration of the resulting cured products varies with each lot. Therefore, the curable organopolysiloxane composition of the present invention is characterized by being free of M4Q structures, and to achieve this, it is necessary to remove the M4Q structures after synthesis of the organopolysiloxane resin of component (B) and before the organopolysiloxane composition of the present invention cures to form a cured product.

[0053] To ensure that the curable organopolysiloxane composition of the present invention does not contain the M4Q structure, the M4Q structure can be removed after the organopolysiloxane resin (component (B)) is synthesized and before being incorporated into the organopolysiloxane composition of the present invention. This can be achieved by drying the particulate organopolysiloxane resin (the crude raw material) obtained after the polymerization reaction in the organopolysiloxane resin production process in an oven or by removing it together with the organic solvent in a twin-screw kneader. More specifically, volatile components can be removed by treating an organopolysiloxane resin containing the M4Q structure at a high temperature of approximately 200°C for a period of time depending on the surface area of ​​the resin, until no further mass loss is observed. For example, if 1 g of the organopolysiloxane composition is cured in an aluminum cup with a diameter of 50 mm and the cured organopolysiloxane is heated in an oven set to 200°C, its mass will decrease for approximately one hour and then remain constant. It is also possible to simultaneously remove organic solvents and volatile components such as M4Q structures from the organopolysiloxane resin that constitutes component (B) using a twin-screw kneader set to 200°C. A residence time of about 5 minutes in the twin-screw kneader is sufficient if the temperature is set to around 200°C. Furthermore, if the cured organopolysiloxane to be treated is in granular form and heated to this temperature while stirring in the atmosphere, the large surface area relative to the volume allows the volatile low-molecular-weight M4Q structures to be removed in a few minutes.

[0054] Such organopolysiloxane resins are produced by polymerization in the presence of an organic solvent that is highly compatible with the raw material monomers. The resulting organopolysiloxane resin can be obtained by removing the organic solvent by drying under reduced pressure or other methods. However, the M4Q structure is more compatible with the organopolysiloxane resin than the organic solvent, making it difficult to remove by simply drying the organic solvent. Furthermore, since components (A), (C), (D), and optional component (E) that make up the curable organosiloxane composition of the present invention do not produce the M4Q structure during their production process, the curable organopolysiloxane composition of the present invention or its cured product can be distinguished from a prior art composition containing an MQ resin containing the M4Q structure instead of component (B) and its cured product by first heating the composition or cured product at 150°C to volatilize the organic solvent, etc., and then heating it at 200°C and measuring the mass loss. Furthermore, the volatilized components can be identified by gas chromatography or other methods. As mentioned above, the M4Q structure itself is less volatile than solvents, and therefore cannot be removed by typical raw material preparation methods, and must be removed by a specific process step aimed at removing the M4Q structure, as described above. Furthermore, because compounds with higher molecular weights than the M4Q structure, such as structures represented by M6Q2 and MVi4Q, do not volatilize at temperatures of around 200°C, this step can be said to be specialized for removing the M4Q structure.

[0055] The amount of component (B) is typically 10 to 80 parts by mass per 100 parts by mass of component (A). More specifically, the amount may be within a range of 10 or more, 15 or more, 20 or more, 40 or more, or 50 or more, and at the same time, 60 or less, 70 or less, or 80 or less. Particularly, the ranges of 10 to 80 parts by mass, 15 to 80 parts by mass, or 40 to 70 parts by mass are exemplified. When component (B) is used within the above range, the amount of M4Q structures that can be contained in the composition of the present invention is 1.0 part by mass or less, or 0.5 part by mass or less. Needless to say, the closer to 0 parts by mass, the better. By analyzing the composition of the present invention by chromatography, the remaining amount of M4Q structures can be quantified from the molecular weight peak of the M4Q structures.

[0056] (C) Organohydrogenpolysiloxane crosslinker Component (C) is a crosslinking agent, an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms (also referred to as SiH groups) per molecule. The SiH groups of component (C) react with the carbon-carbon double bonds contained in component (A) and other components in the presence of a hydrosilylation catalyst, thereby curing the organopolysiloxane composition of the present invention, which is a crosslinkable composition.

[0057] (C) component is HR 3 2SiO 1 / 2 Monovalent hydrogenorganosiloxy units (M H It is expressed as a unit. 3 are independently monovalent organic groups), or HR 3 SiO 2 / 2 Divalent hydrogenorganosiloxy units (D H It is expressed as a unit. 3 The organohydrogenpolysiloxane may be any organohydrogenpolysiloxane having (independently monovalent organic groups) M. The structure is not particularly limited, and may be linear, branched, cyclic, or resinous. Specific structures of component (C) include: HHowever, when the cured organopolysiloxane obtained by curing the curable organopolysiloxane composition of the present invention is used in an application requiring heat resistance, if unreacted SiH components remain in the system, further crosslinking may proceed at high temperatures, which may cause changes in penetration. H M is more reactive than the methyl group, and all SiH groups in the system react quickly. H It is preferable to use an organohydrogenpolysiloxane containing units. The amount of silicon-bonded hydrogen atoms in component (C) can be measured using an infrared spectrometer.

[0058] Component (C) may consist solely of (C-1) linear organohydrogenpolysiloxane, or may be a mixture of (C-1) linear organohydrogenpolysiloxane and (C-2) branched organohydrogenpolysiloxane. Each component is described below.

[0059] The linear organohydrogenpolysiloxane of component (C-1) reacts with component (A) and acts as a crosslinking agent for the composition. This linear organohydrogenpolysiloxane contains two silicon-bonded hydrogen atoms (SiH groups) per molecule and has a viscosity in the range of 2 to 10,000 mPa·s. Component (C-1) has little or no branched structure and is predominantly linear. It may have a linear structure, with the SiH groups located at both ends of the chain. This type of component (C-1) can be represented by the following average structural formula (4): (HR 3 2SiO 1 / 2 )2(R 3 2SiO 2 / 2 ) v (4) In formula (4), R 3represents the same group as i) the monovalent hydrocarbon group not having an aliphatic unsaturated carbon bond in component (B) described above, and from an industrial viewpoint, examples include a methyl group or a phenyl group. In the formula, v is a number of 1 or more, and preferably 2+v is 500 or less. Specific structures include those represented by the following average structural formula: (H(Me)2SiO 1 / 2 )(Me2SiO 2 / 2 ) v1 (SiO 1 / 2 (Me)2H) (wherein Me is a methyl group) An example of such a compound is an unbranched dimethylpolysiloxane in which both molecular chain terminals are capped with dimethylhydrogensiloxy groups, as represented by the formula: where v1 is a number such that the viscosity at 25°C is in the range of 2.0 to 500 mPa·s, or in the range of 2.0 to 150 mPa·s. In other words, v1 is an integer that is 1 or greater and 50 or less, 100 or less, or 200 or less. Other examples include the following linear organohydrogenpolysiloxanes: where Me and Ph represent methyl and phenyl groups, respectively, v2 is an integer from 1 to 100, and v3 is an integer from 1 to 50. HMe2SiO(Ph2SiO) v2 SiMe2H HMePhSiO(PhSiO) v2 SiMePhH HMePhSiO(PhSiO) v2 (MePhSiO) v3 SiMePhH HMePhSiO(PhSiO) v2 (Me2SiO) v3 SiMePhH

[0060] The content of the linear organohydrogenpolysiloxane (C-1) in the organopolysiloxane composition is, for example, an amount within a range such that the number of hydrogen atoms bonded to silicon atoms per alkenyl group in component (A) exceeds 0, or is 0.1 or greater, and at the same time is 1.5 or less, or 1.2 or less.

[0061] The viscosity of component (C-1) at 25°C is in the range of 2.0 to 10,000 mPa·s, but may also be in the range of 2.0 to 5000 mPa·s, or even 2.0 to 1000 mPa·s. A component (C-1) having such a viscosity contributes to improving the handling and flowability of the organopolysiloxane composition of the present invention, as well as the strength of the resulting cured product.

[0062] The branched organohydrogenpolysiloxane of component (C-2) is used in combination with the aforementioned component (C-1), reacting with the above-mentioned component (A) and acting as a crosslinking agent for the present composition. Because such branched organohydrogenpolysiloxanes have a branched structure, R 4 SiO 3 / 2 or SiO 4 / 2 The siloxane units represented by the following formula are contained in a proportion of at least 20 mol % of all siloxane units in the molecule. If the amount of these branched units is less than the lower limit, it may not be possible to effectively adjust the penetration of the resulting organopolysiloxane cured product.

[0063] Furthermore, component (C-2) has at least three hydrogen atoms bonded to silicon atoms (SiH groups) per molecule. The number of SiH groups in component (C-2) per molecule is three or more, but may be four or more, five or more, or ten or more, and may also be 500 or less, 200 or less, 100 or less, or 80 or less.

[0064] The component (C-2) may be an organohydrogenpolysiloxane represented by the following average unit formula (5): (R 4 3SiO 1 / 2 ) j (R 4 2SiO 2 / 2 ) k (R 4 SiO 3 / 2 ) m (SiO 4 / 2 ) n (R 5 O 1 / 2 ) p (5) (wherein j, k, m, n, and p are numbers that satisfy the following: 0.1≦j≦0.80, 0≦k≦0.5, 0≦m≦0.8, 0≦n≦0.6, 0≦p≦0.05, with the proviso that m+n≧0.2 and j+k+m+n=1.) In the formula, each R 4 are the same or different monovalent hydrocarbon groups having 1 to 10 carbon atoms and no aliphatic unsaturated carbon bonds, or hydrogen atoms, provided that at least three R 4 is a hydrogen atom. R other than a hydrogen atom 4 The number of carbon atoms in the monovalent hydrocarbon group may be an integer of 1 or more and 2 or less, 3 or less, 4 or less, or 6 or less, or may be an integer of 6 or more, 7 or more, and 8 or less, 9 or less, or 10 or less. Specific examples of unsubstituted or substituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated bonds include alkyl groups, aryl groups, aralkyl groups, alkyl groups, aryl groups, aralkyl groups, and groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms such as chlorine, bromine, or fluorine. Among these, methyl groups, ethyl groups, phenyl groups, and benzyl groups are particularly preferred, and from an industrial standpoint, methyl groups and phenyl groups are particularly preferred because of their ease of synthesis.

[0065] On the other hand, R 5 is a hydrogen atom or an alkyl group having carbon atoms that is an integer of 1 or more and 2 or less, 3 or less, 4 or less, or 6 or less, or an integer of 6 or more, 7 or more, and 8 or less, 9 or less, or 10 or less. 5 O 1 / 2 R represents a hydroxyl group or an alkoxy group. 5 Particularly, examples of OR include a hydrogen atom, a methyl group, and an ethyl group. 5 Examples of the alkyl group include a hydroxyl group, a methoxy group, and an ethoxy group.

[0066] In the formula, j, k, m, n, and p are numbers that satisfy the following: 0.1≦j≦0.80, 0≦k≦0.5, 0≦m≦0.8, 0≦n≦0.6, 0≦p≦0.05, with the proviso that m+n≧0.2 and j+k+m+n=1, with k=0 being a particular example. When the present composition is used for heat-resistant applications, the resinous organohydrogenpolysiloxane that is an example of component (C-2) is specifically M H MT resin, M H MTT H Resin, M H MTQ resin, M H MQ resin, M H MTT H Q, M H Examples of such resins include the siloxane units contained therein, e.g., M H MTQ resin is M unit, M H It is a resin containing M units, T units, and Q units in any proportion. H The units, T units, and Q units are as described above. H The unit is HSiO 3 / 2 In particular, the component (C-2) is (H(CH3)2SiO 1 / 2 ) j1 (SiO 4 / 2 ) n1 M H Q resin, where j1+n1=1, 0.1≦j1≦0.80, and 0.20≦n1≦0.90 are exemplified.

[0067] The content of component (C-2) is exemplified by an amount that results in 0.05 to 0.8 SiH groups per alkenyl group in component (A). More specifically, an amount in the range of 0.05 or more, or 0.1 or more, and at the same time 0.8 or less, or 0.75 or less, is particularly exemplified. By keeping the content of component (C-2) in the organopolysiloxane composition within this range, it is possible to effectively control the hardness of the organopolysiloxane cured product without excessively reducing its penetration. If the number of SiH groups contained in component (C-2) per alkenyl group in component (A) is below the above-mentioned lower limit, it becomes difficult to adjust the penetration of the organopolysiloxane cured product using this component.

[0068] The viscosity of component (C-2) at 25°C is in the range of 2.0 to 10,000 mPa·s, preferably 2.0 to 5000 mPa·s, and more preferably 2.0 to 1000 mPa·s. The addition of component (C-2) with such a viscosity improves the handling and flowability of the composition and the strength of the resulting cured product.

[0069] In addition to adjusting the penetration of the resulting organopolysiloxane cured product, component (C-2) is effective in improving crack resistance (particularly cracking and breakage due to internal stress caused by temperature differences within a component). From the standpoint of physical properties, including heat resistance, cold resistance, and crack resistance, of the organopolysiloxane cured product obtained by curing the organopolysiloxane composition of the present invention, the total number of hydrogen atoms bonded to silicon atoms in components (C-1) and (C-2) is 0.7 or more, or 0.8 or more, and simultaneously 1.2 or less, or 1.0 or less, per 1.0 alkenyl group contained in the entire composition.

[0070] (D) Hydrosilylation reaction catalyst Component (D) of the present invention is used as a catalyst to promote the hydrosilylation reaction between silicon-bonded alkenyl groups in component (A) and silicon-bonded hydrogen atoms in component (C). Examples of component (D) include platinum-based catalysts, rhodium-based catalysts, palladium-based catalysts, and non-platinum metal catalysts such as iron, ruthenium, and iron / cobalt. Platinum-based catalysts are particularly preferred because of their ability to significantly accelerate the curing of the composition. While known catalysts can be selected, platinum-alkenylsiloxane complexes are representative. While the alkenylsiloxane structure is not limited, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is an example due to the excellent stability of the complex. It is preferable to add the complex in the form of an alkenylsiloxane solution. Additionally, from the standpoint of improving handling and the pot life of the composition, a platinum-containing hydrosilylation catalyst in the form of fine particles dispersed or encapsulated in a thermoplastic resin may be used. These hydrosilylation reaction catalysts may be used either individually or in combination of two or more.

[0071] In the case of a platinum-containing hydrosilylation catalyst in the form of fine particles dispersed or encapsulated in a thermoplastic resin, the platinum-based addition reaction catalyst (component (D))) may be a thermoplastic resin fine particle containing a platinum-containing hydrosilylation catalyst, which is a catalyst dispersed or encapsulated in a thermoplastic resin such as a silicone resin, a polycarbonate resin, an acrylic resin, etc. Also, part or all of component (D) may be a catalyst that becomes active in the composition only upon irradiation with high-energy rays, and may be a high-energy ray-activated catalyst or a photoactivated catalyst, such as (methylcyclopentadienyl)trimethylplatinum(IV) or bis(2,4-pentanedionato)platinum(II).

[0072] The amount of component (D) may be an effective amount and can be increased or decreased as appropriate depending on the desired curing rate, but in the case of a platinum catalyst, for example, the amount of platinum metal is usually within the range of 0.1 to 1,000 ppm, preferably 1 to 300 ppm, based on the mass of the entire composition. Amounts exceeding the upper limit of the aforementioned range are not advantageous in terms of curing rate and are economically disadvantageous in terms of the price (cost) of platinum.

[0073] (E) (e1) a reaction product of an alkali metal silanolate and (e2) at least one cerium salt selected from cerium chloride and carboxylates of cerium Component (E) is an optional component that can be used when organopolysiloxane compositions containing the organopolysiloxane composition of the present invention and / or their cured products are used in applications requiring higher heat resistance. This reaction product, component (E), is described, along with its production method, in, for example, Japanese Patent Application Laid-Open Nos. 49-83744 and 60-240761; the individual components that produce component (E) and the reactions they undergo are summarized below.

[0074] (e1) Alkali metal silanolate can be obtained, for example, by subjecting (e1-1) one or more types of cyclic organopolysiloxane to a ring-opening reaction with (e1-2) an alkali metal hydroxide, to obtain a reaction product, and then further reacting this product with (e1-3) an organopolysiloxane having a viscosity at 25°C in the range of 10 to 10,000 mPa s.

[0075] There are no particular restrictions on the cyclic organopolysiloxane of component (e1-1), but examples include cyclic organopolysiloxanes having the following general formula (6): [ka] In formula (6), R represents a monovalent hydrocarbon group similar to R in general formula (1) of component (A) described above, and s and t are each integers from 0 to 8, with the proviso that 3≦s+t≦8. Specific examples of the (e1-1) cyclic organopolysiloxane include hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6), as well as organopolysiloxanes in which some of the methyl groups have been substituted with other hydrocarbon groups, hydrogen groups, or reactive groups such as (meth)acryloxy groups, carboxyl groups, vinyl groups, and aminopropyl groups, and mixtures of these various organopolysiloxanes are also possible.

[0076] The alkali metal hydroxide of component (e1-2) is not particularly limited, but examples include sodium hydroxide and potassium hydroxide. The amount of component (e1-2) is generally 0.1 to 10 parts by mass per 100 parts by mass of component (e1-1), but is not limited to this amount and can be adjusted depending on the reaction conditions.

[0077] The organopolysiloxane of component (e1-3) may be any conventional linear organopolysiloxane having a viscosity at 25°C in the range of 10 to 10,000 mPa·s, and may contain some branching as long as it remains liquid at room temperature. The silicon atoms of the siloxane units are bonded to unsubstituted or substituted monovalent hydrocarbon groups (which may be monovalent alkenyl groups) similar to those exemplified as R in general formula (1) of component (A). The molecular chain terminals of this organopolysiloxane may be blocked with triorganosiloxy groups such as trialkylsiloxy groups (e.g., trimethylsiloxy), alkenyldialkylsiloxy groups (e.g., vinyldimethylsiloxy), dialkenylalkylsiloxy groups (e.g., divinylmethylsiloxy), and trialkenylsiloxy groups (e.g., trivinylsiloxy), or with hydroxyl or alkoxy groups.

[0078] The viscosity of the organopolysiloxane of component (e1-3) is within the range of 10 mPa·s or more, or 50 mPa·s or more, at 25°C, and simultaneously 1,000 mPa·s or 10,000 mPa·s. If the viscosity of component (e1-3) is 10 mPa·s or less, there is a problem that the amount of evaporation at high temperatures tends to be large, resulting in a large change in mass. There are no particular restrictions on the amount of component (e1-3), but it is generally 0.1 to 10 parts by mass per 100 parts by mass of component (e1-1).

[0079] The reaction of components (e1-1), (e1-2), and (e1-3) to obtain component (e1) is known from, for example, the aforementioned JP-A-60-240761, and is exemplified by adding component (e1-2) to component (e1-1) at room temperature to open the ring of component (e1-1), to which component (e1-3) is then added and reacted for 2 hours at, for example, 115°C under a nitrogen stream.

[0080] The cerium salt of component (e2) is a chloride or carboxylate of cerium or a rare earth element mixture containing cerium as the main component. 1 Chloride, denoted by Cly, and (R 4 COO)yM 1 (wherein R 4 are the same or different monovalent hydrocarbon groups, M 1 is cerium or a rare earth element mixture mainly composed of cerium, and y is M 1 The carboxylic acid is exemplified by 2-ethylhexanoic acid, naphthenic acid, oleic acid, lauric acid, stearic acid, etc. 1 The chlorides or carboxylates of the above are preferably used as a solution in a lower alcohol or an organic solvent because of their ease of handling. Examples of lower alcohols include methanol and ethanol, and examples of organic solvents include petroleum-based solvents such as Stoddard solvent (mineral spirits), ligroin, and petroleum ether, and aromatic solvents such as toluene and xylene.

[0081] The amount of component (e2) is M1 An example of the amount is 0.05 or more, or 0.1 or more parts by mass, and at the same time 5 or less parts by mass, or 3 or less parts by mass, but is not limited to these amounts and may be adjusted depending on the reaction conditions.

[0082] The amount of component (E) added may be 0.20 or more, or 0.3 or more, in terms of parts by mass per 100 parts by mass of component (A), but may also be within the range of 10.0 or less, 5.0 or less, or 0.5 or less, more specifically, it is added in a small amount of about 0.2 parts by mass, 0.3 parts by mass, or 0.4 parts by mass. Furthermore, the amount of component (E) added is determined based on the ratio of M in component (E) to the total amount of the composition. 1 The content is exemplified as an amount within the range of 0.005% or more, or 0.01% or more, and at the same time 0.15% or 0.1% by mass. 1 Most of them are M 1 Although it exists as a silanolate, a silicon-containing compound having at least one unit in which an oxygen atom is bonded to a silicon atom, other forms are also measured as being contained in component (E). Keeping the amount of component (E) within this range is advantageous in terms of the heat resistance of the resulting organopolysiloxane composition. If the amount of component (E) is less than 0.20 parts by mass, the effect of improving heat resistance at high temperatures is not observed. Conversely, if it exceeds 10 parts by mass, the transparency of the organopolysiloxane cured product is reduced and the cost of the organopolysiloxane composition increases, which is economically disadvantageous.

[0083] Component (E) can be obtained, for example, by dissolving component (e1) obtained as described above in a suitable solvent (e.g., isopropanol), adding a solution of component (e2) dropwise at room temperature to mix components (e1) and (e2), followed by heat treatment at a temperature of 150°C or higher, recovering the solid reaction product by filtration, and removing the solvent under reduced pressure and weak heating. The heating temperature in this heat treatment can be 150°C or higher, 200°C or higher, or 250°C or higher, but also 310°C or lower, 305°C or lower, or 300°C or lower. Heating temperatures below 150°C make it difficult to obtain a uniform composition, while temperatures above 310°C can cause problems, such as the rapid thermal decomposition of component (e1-3).

[0084] The high-strength organosiloxane cured product of the present invention further contains component (E), which allows it to maintain flexibility even under high-temperature conditions for extended periods and continuously exhibit the desirable characteristics of a low elastic modulus and low stress. In other words, the addition of component (E) to the organopolysiloxane composition of the present invention makes it possible to produce an organopolysiloxane cured product that has excellent heat resistance and transparency at temperatures exceeding 200°C, and that maintains a low elastic modulus, low stress, and high transparency even after long-term use at high temperatures, while also possessing crack resistance.

[0085] Other optional ingredients In addition to the above components (A) to (D) and the optional component (E), the composition of the present invention may contain optional components such as a reaction inhibitor, an inorganic filler, an organopolysiloxane that does not contain silicon-bonded hydrogen atoms or silicon-bonded alkenyl groups, an adhesion promoter, a heat resistance promoter, a flame retardant, a thixotropy promoter, a pigment, or a dye, provided that the object of the present invention is not impaired.

[0086] The tackifier is a component that improves the adhesion of the organopolysiloxane to a substrate or the like, and can be appropriately selected from those generally known to those skilled in the art. It is preferable to select a substance or a quantitative range for the type and amount of the tackifier so that it does not reduce the transparency of the cured organopolysiloxane product or cause curing inhibition. Any tackifier can be used within a range that provides an organopolysiloxane composition in which the cured organopolysiloxane product of the present invention is substantially transparent when evaluated by the method described in the Examples section of this application, and has a direct reading of 1 / 4 consistency as specified in JIS K2220 of 200 or less. Titanium compounds such as tetraethyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetra(2-ethylhexyl) titanate, titanium ethylacetonate, and titanium acetylacetonate, as well as titanium compounds of the general formula (R a O) z SiR b (4-z) (where R a represents an alkyl or alkoxyalkyl group, and R b represents an unsubstituted or substituted monovalent hydrocarbon group, and z is 3 or 4), and examples thereof include silanes and their partial hydrolysis condensates or combinations thereof, particularly silane coupling agents such as methyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-aminopropyltrimethoxysilane. The content of the adhesion promoter is not limited and can be appropriately determined, but is generally within the range of 0.001 to 5 mass% of the total composition.

[0087] The reaction inhibitor is a component for inhibiting the hydrosilylation reaction of the organopolysiloxane composition and can be appropriately selected from those generally known to those skilled in the art, such as acetylene-based, amine-based, carboxylic acid ester-based, and phosphite-based reaction inhibitors. The amount of reaction inhibitor added is generally 0.001 to 5 mass% of the total organopolysiloxane composition. In particular, for the purpose of improving the handling properties of the organopolysiloxane composition of the present invention, acetylene alcohol compounds such as ethynylcyclohexanol, 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 3-phenyl-1-butyn-3-ol; enyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; cycloalkenylsiloxanes such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; and triazole compounds such as benzotriazole can be used without particular limitation.

[0088] Inorganic fillers can be added to further increase mechanical strength. While the type of filler is not particularly limited, when low viscosity and transparency are required for the organopolysiloxane composition, it is common to not incorporate inorganic fillers. If inorganic fillers are incorporated, a content of 20% by weight or less, particularly 10% by weight or less, can ensure transparency in the cured product. The use of nanoparticles can also maintain transparency. When transparency is not an issue, examples of inorganic fillers that can be used include fumed silica, crystalline silica, precipitated silica, hollow fillers, silsesquioxane, fumed titanium dioxide, magnesium oxide, zinc oxide, iron oxide, aluminum hydroxide, magnesium carbonate, calcium carbonate, zinc carbonate, layered mica, carbon black, diatomaceous earth, and glass fiber; and fillers obtained by surface-hydrophobizing these fillers with organosilicon compounds such as organoalkoxysilane compounds, organochlorosilane compounds, organosilazane compounds, and low-molecular-weight siloxane compounds. Silicone rubber powder, silicone resin powder, and the like may also be incorporated.

[0089] [Preparation of Organopolysiloxane Composition] The organopolysiloxane composition of the present invention can be prepared by mixing the above-mentioned components (A) to (D) (including component (E) and other optional components, if blended) in a conventional manner. In this case, the components to be mixed may be divided into two or more parts and mixed as needed. For example, the composition may be divided into a part consisting of a portion of component (A) and (B), (C), and optional components, and a part consisting of the remainder of component (A) and component (D), and then these two parts may be mixed together to prepare the composition. It is particularly preferred that one of the parts contains the above-mentioned reaction inhibitor as an optional component.

[0090] The method for mixing the components of the silicone composition may be a conventionally known method and is not particularly limited, but usually a uniform mixture can be obtained by simple stirring. Furthermore, when solid components such as inorganic fillers are included as optional components, mixing using a mixing device is more preferable. Such mixing devices are not particularly limited, and examples include single-screw or twin-screw continuous mixers, twin-roll mixers, Ross mixers, Hobart mixers, dental mixers, planetary mixers, kneader mixers, Henschel mixers, etc.

[0091] The organopolysiloxane composition thus obtained can be suitably used as a sealant for electronic components or a laminating agent for displays. In particular, by using an organopolysiloxane composition containing component (E) as a sealant for semiconductor chips or a laminating agent for displays, the composition can effectively protect the semiconductor chip or display after curing without causing cracks due to heat sources or localized heating, even in harsh environments where excellent heat resistance is required.

[0092] [Curing of Organopolysiloxane Composition] The organopolysiloxane composition of the present invention can be cured by a hydrosilylation reaction at room temperature or at a temperature appropriate for the application to form a gel-like organopolysiloxane cured product having a hardness within the range in which a direct reading of 1 / 4 consistency as specified in JIS K2220 shown below can be measured. The temperature conditions for curing are not particularly limited, but in practice, they are usually within the range of 60°C to 150°C. The organopolysiloxane cured product prepared in this manner is also an embodiment of the present invention.

[0093] [Cured organopolysiloxane] The organopolysiloxane cured product of the present invention has excellent mechanical strength and adhesive properties, making it suitable for use as a laminating agent for displays, which are becoming larger in area and have a wider temperature range for reliability. Furthermore, by using component (E) in combination, the product exhibits excellent heat resistance and transparency at temperatures exceeding 200°C, and can maintain a low modulus of elasticity, low stress, and high transparency even after long-term use at high temperatures. Furthermore, even when the organopolysiloxane cured product is left exposed to high temperatures on only one side for a long period of time, such as when a high-temperature heat source is installed on only one side (e.g., the bottom surface), the organopolysiloxane cured product is less likely to develop defects such as cracks due to temperature differences and internal stresses within the component. When component (E) is contained, and further, when used for protecting electronic components such as semiconductor chips, SiC semiconductor chips, ICs, hybrid ICs, and power devices, the composition maintains transparency and excellent heat resistance even at high temperatures, which is expected to improve long-term durability. Furthermore, the composition is resistant to degradation even at low temperatures, which has the advantage of providing electronic components with high reliability and durability even under harsh operating conditions with large temperature fluctuations. In particular, electronic components that incorporate the organopolysiloxane cured product as a sealant or the like have high reliability and durability even under harsh operating conditions with large temperature fluctuations. The semiconductor chips mentioned above include light-emitting semiconductor elements such as LEDs.

[0094] (1 / 4 consistency) The organopolysiloxane cured product of the present invention has a direct reading of 1 / 4 penetration (measured in 1 / 10 mm) as specified in JIS K2220 of 10 or more, 20 or more, or 30 or more, and simultaneously 150 or less, 120 or less, or 100 or less. Organopolysiloxane cured products exhibiting direct readings of 1 / 4 penetration as specified in JIS K2220 within these ranges possess the characteristics of organopolysiloxane cured products, such as a low elastic modulus and low stress. If the penetration is less than 10, it is difficult to exhibit the characteristics of organopolysiloxane cured products, such as a low elastic modulus and low stress. If the penetration is more than 150, the organopolysiloxane cured product will have difficulty maintaining its shape and will flow. The "direct reading of 1 / 4 consistency" is the value obtained by dropping a 1 / 4 cone from the surface of a sample using a 1 / 4 consistency tester specified in JIS K2220, in the same way as in the 1 / 4 cone penetration test specified in JIS K2220, and reading the depth to which this cone penetrates.

[0095] (transparency) The organopolysiloxane cured product of the present invention is preferably transparent, particularly when used in display applications. On the other hand, when used as a sealant for power devices, etc., coloring is acceptable, but substantially transparent is industrially preferred. "Substantially transparent" means that a 10 mm-thick organopolysiloxane cured product is obtained by gently pouring a pre-degassed silicone gel composition into an aluminum cup, visually confirming the absence of air bubbles, and then heating at a temperature of 80°C to 150°C. When viewed from above, the bottom of the aluminum cup can be seen with the naked eye. The organopolysiloxane cured product possessing such transparency is useful as a sealant for semiconductors such as power devices.

[0096] Because the organopolysiloxane cured product of the present invention imparts excellent durability to electronic components equipped with it, one embodiment of the present invention is a method for protecting electronic components, which involves 1) placing an organopolysiloxane composition and its sealing or laminating member in contact with or near an electronic component such as a semiconductor, and 2) curing the composition by heating, and placing the resulting cured product in place. Heating can be carried out at a temperature ranging from approximately 80°C to 150°C until the composition loses fluidity, although this depends on the heat resistance of the electronic component and the circuit board on which it is mounted.

[0097] Another aspect of the present invention is an electronic component comprising the cured organopolysiloxane described above, such as an in-vehicle electronic component, a consumer electronic component, or a display component. The electronic component may be an optoelectronic component, such as an LED or other light-emitting semiconductor element. General lighting fixtures incorporating such components are also included in the present invention. In particular, electronic components incorporating the cured organopolysiloxane containing component (E) may be those exposed to severe temperature changes, such as those experienced in outer space. Another aspect of the present invention also includes electronic components incorporating power semiconductors, particularly SiC semiconductors, that are exposed to cycles of high temperatures of 200°C or higher and cooling, and devices incorporating such components. Examples of power devices incorporating power semiconductors include motor controls, motor controls for transport aircraft, power generation systems, and space transportation systems. [Example]

[0098] The organopolysiloxane composition and cured silicone product of the present invention are described in detail below using examples. However, the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. Viscosity values ​​in the examples are measured at 25°C.

[0099] [Production of component (E)] Component (E) was prepared using the following method. A mixture of hexamethylcyclotrisiloxane and octamethylcyclotetrasiloxane was subjected to a ring-opening reaction with potassium hydroxide to prepare a potassium silanolate compound. 100 g of this potassium silanolate compound was dissolved in 150 g of isopropanol, and a mixture of 2.5 g of anhydrous cerium chloride, 50 g of ethanol, and 50 g of methanol was added dropwise while stirring to allow the reaction to proceed. After filtering the reaction mixture, the filtrate was heated to 40-50°C under reduced pressure to distill off the ethanol and methanol. The mixture was then filtered again to prepare a pale yellow liquid reaction product. The cerium content in this reaction product was 1.4% by mass.

[0100] [Evaluation of Organopolysiloxane Composition and Cured Organopolysiloxane] The transparency, 1 / 4 consistency, heat resistance, and crack resistance of the organopolysiloxane cured product of the present invention were measured as follows.

[0101] (Preparation of cured organopolysiloxane) The organopolysiloxane composition was gently poured into a 50 ml glass beaker to a height of 3 cm from the bottom of the beaker, and then heated at 80° C. for 1 hour to produce a cured organopolysiloxane.

[0102] (1 / 4 consistency measurement) Similar to the 1 / 4 cone penetration test specified in JIS K2220, a 1 / 4 cone was dropped from the surface of the target organopolysiloxane cured product using a 1 / 4 cone penetration meter specified in JIS K2220, and the depth to which the cone penetrated was read (reading units were 1 / 10 mm), and this value was recorded as the "direct reading value."

[0103] (Heat resistance of cured organopolysiloxane) The organopolysiloxane cured product cured by the above method was placed in an oven at 225°C, removed after 1000 hours, and allowed to stand at room temperature to cool naturally to 25°C. The 1 / 4 consistency of this organopolysiloxane cured product was then measured, and the direct reading (reading unit: 1 / 10 mm) was recorded as the 1 / 4 consistency.

[0104] (Crack resistance of cured organopolysiloxane) The organopolysiloxane cured product obtained by the above method was placed on a hot plate heated to 225°C, and the appearance of the organopolysiloxane was observed through a beaker for 1000 hours. If cracks were visually observed within 1000 hours, the time was recorded.

[0105] (Mechanical strength and adhesive strength of cured organopolysiloxane) Using two 25mm x 75mm x 1mm aluminum plates, adhesive strength and mechanical strength were measured according to the method specified in JIS K6850 / 1999. Note that when the test ends with cohesive failure of the organopolysiloxane, the adhesive strength directly indicates the mechanical strength of the organopolysiloxane.

[0106] [Examples 1 to 8 and Comparative Examples 1 to 13] Twenty-one organopolysiloxane compositions were prepared by uniformly mixing the components shown in Tables 1, 2, 3, and 4 below in the proportions (parts by mass) shown in Tables 5 and 6. These organopolysiloxane compositions were cured using the methods described above for each composition. The resulting cured organopolysiloxanes were evaluated for 1 / 4 consistency, heat resistance, and crack resistance, and the results are summarized in Tables 5 and 6. In the tables, SiH / Vi indicates the number of moles of silicon-bonded hydrogen atoms in components (C-1) and (C-2) combined per mole of vinyl groups contained in components (A-1), (A-2), and (D) combined. The platinum metal content of component (D) is shown in ppm of the composition.

[0107] [Table 1]

[0108] [Table 2] * The volatilization amount is the mass loss expressed as a percentage when approximately 1g of this organopolysiloxane resin is weighed into a 50mm diameter aluminum cup and left at 200°C for 1 hour. As mentioned above, this figure corresponds to the amount of M4Q structure remaining in component B.

[0109] [Table 3] *SiH content = content of silicon-bonded hydrogen atoms

[0110] [Table 4]

[0111] [Summary] As shown in Table 5, Examples 1 to 5 demonstrate the performance of the basic organopolysiloxane composition of the present invention. These compositions, containing the characteristic (B) component of the present invention, exhibited higher adhesive strength and mechanical strength than Comparative Examples 1 and 2, which lacked sufficient amounts of component (B). This demonstrates that compositions containing component (B) can provide tougher organopolysiloxane compositions. Comparative Examples 3 and 4 also confirm the contribution of component (C) to the performance of the present invention. Furthermore, Comparative Examples 5 and 6, which have the same composition as Example 4 except that component (B) contains volatile components, exhibited relatively poorer strength, with high and variable 1 / 4 consistency values. Therefore, the basic organopolysiloxane cured product of the present invention exhibits consistently high strength and is suitable for applications requiring high strength. Table 6 also shows Examples 6 to 8 and a Comparative Example, which further contain the optional component (E). The heat resistance of the organopolysiloxane cured products obtained from these compositions and their crack resistance when heated from one direction at 225°C for an extended period of time were generally good, and there was no significant change in 1 / 4 consistency after 1000 hours at high temperature, but strength was significantly inferior when component (B) was not included, as in Comparative Examples 7 to 11. Furthermore, the compositions of Comparative Examples 12 and 13 had the same compositions as those of Examples 7 and 8, respectively, except that component (B) contained a volatile component. However, because they did not contain component (B) such that the mass loss rate after exposure at 200°C for 1 hour, which is a characteristic of the present invention, was 2.0% by mass or less, their crack resistance was significantly inferior.

[0112] Table 5. Performance of the base composition [Table 5] (*1) Calculated from the amount of the component contained in component B that volatilizes at 200°C, i.e., the amount of M4Q structure. (*2) Since the failure mode in all adhesion tests was cohesive failure, adhesive strength = mechanical strength of the cured organopolysiloxane.

[0113] Table 6. Effect of component (B) in heat-resistant organopolysiloxane compositions containing component (E) [Table 6] (*1) Calculated from the amount of the component contained in component B that volatilizes at 200°C, i.e., the amount of M4Q structure. (*2) Since the failure mode in all adhesion tests was cohesive failure, adhesive strength = mechanical strength of the cured organopolysiloxane. [Industrial Applicability]

[0114] The organopolysiloxane cured product obtained from the organopolysiloxane composition of the present invention has strength and transparency, and thus can be used in various applications, such as encapsulants for semiconductor devices, protective materials, encapsulants for optical devices, adhesive materials for displays, optical or optoelectronic components used in general lighting fixtures, lenses (including secondary optical lens materials provided on the outside of LED packages), light diffusing materials, white reflector materials, wavelength conversion materials, optical waveguides, and light guides. When used as optical or optoelectronic components, various functional fillers (fluorescent, light diffusing, translucent, colorable, reinforcing fillers, etc.) may be added to the organopolysiloxane composition of the present invention. The organopolysiloxane composition of the present invention can be used in the same manner as conventional organopolysiloxane compositions having similar optical properties, and its high strength provides better protection of devices and parts containing it than conventional compositions, thereby improving reliability.

[0115] Furthermore, the organopolysiloxane cured product obtained from the organopolysiloxane composition of the present invention containing component (E) not only exhibits heat resistance of 200°C or higher, as required for SiC semiconductor chips, but also resists cracking even when exposed to high temperatures from only one direction, allowing for greater flexibility in circuit design, including thermal management. It is also suitable for use as a sealant or protective material for power devices in which heat is generated only from the bottom of the device, thereby improving the durability and reliability of such power devices. Examples of power devices requiring such heat resistance and crack resistance include general-purpose inverter control, servo motor control, motor control for machine tools and elevators, motor control for electric vehicles, hybrid cars, and railway transport vehicles, power generator systems for solar, wind, and fuel cell power generation, and space transportation systems used in outer space.

Claims

1. (A) 100 parts by mass of an organopolysiloxane having an average of at least two silicon-bonded alkenyl groups per molecule and having a viscosity at 25°C in the range of 10 to 10,000 mPa s; (B) a mass loss rate of 2.0% by mass or less relative to the mass of component (B) when exposed to 200°C for 1 hour, the mass loss rate being determined by the following formula: (R １ ３ SiO １／２ ) ａ (SiO ４／２ ) ｂ (R ２ O １／２ ) ｃ (In the formula, each R １ are independently a monovalent hydrocarbon group having 1 to 10 carbon atoms and no aliphatic carbon-carbon double bond; R ２ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms; and a, b, and c are numbers satisfying 0.35≦a≦0.55, b=1−a, and 0≦c≦0.05: 10 to 80 parts by mass of an organopolysiloxane resin, (C) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule and having a viscosity at 25°C in the range of 2 to 10,000 mPa·s: in an amount such that the number of silicon-bonded hydrogen atoms per silicon-bonded alkenyl group in the entire composition is 0.5 to 2.0; (D) a hydrosilylation catalyst in an amount sufficient to react and cure (A) with (C); and (E) (e1) alkali metal silanolate and (e2) M １ Cl ｙ and chlorides represented by (R ４ COO) ｙ M １ (wherein R ４ are the same or different monovalent hydrocarbon groups, M １ is cerium or a rare earth element mixture mainly composed of cerium, and y is M １ at least one salt selected from 1) to 3) depending on the valence of the An organopolysiloxane composition comprising:

2. M ４ 2. The organopolysiloxane composition according to claim 1, wherein the content of the Q structure is 1.0 part by mass or less.

3. 3. The organopolysiloxane composition according to claim 1, wherein component (A) is (A-2) a linear organopolysiloxane having at least two silicon-bonded alkenyl groups in each molecule and having a viscosity at 25°C in the range of 10 to 10,000 mPa s.

4. The component (C) (C-1) A linear organohydrogenpolysiloxane having a viscosity at 25°C in the range of 2 to 1,000 mPa·s and having two silicon-bonded hydrogen atoms per molecule: the amount of silicon-bonded hydrogen atoms per silicon-bonded alkenyl group in the entire composition is greater than 0 and not more than 2.0, and optionally (C-2) A copolymer having a viscosity at 25°C of 2 to 1,000 mPa·s, having three or more hydrogen atoms bonded to silicon atoms in the molecule, and R ４ SiO ３／２ (In the formula, R ４ is a monovalent hydrocarbon group) or SiO ４／２ a branched organohydrogenpolysiloxane containing siloxane units represented by the formula: in an amount such that the number of silicon-bonded hydrogen atoms per silicon-bonded alkenyl group in the entire composition is 0.1 to 0.8; The organopolysiloxane composition according to any one of claims 1 to 3, comprising:

5. The component (E) is 0.5 to 5.0 mass % of M 1 3. The organopolysiloxane composition according to claim 1, which contains atoms.

6. 2. The organopolysiloxane composition according to claim 1, wherein the amount of component (B) is from 10 parts by weight to 2800 / 65.3 parts by weight.

7. An electronic component sealant comprising the organopolysiloxane composition according to any one of claims 1 to 6.

8. 7. A cured organopolysiloxane obtained by curing the organopolysiloxane composition according to claim 1, wherein the direct reading of the 1 / 4 consistency as specified in JIS K2220 is within the range of 10 to 150.

9. An electronic component comprising the electronic component sealant according to claim 7 or the organopolysiloxane cured product according to claim 8.

10. A method for protecting a semiconductor chip, comprising using the organopolysiloxane composition according to any one of claims 1 to 6, the electronic component sealant according to claim 7, or the organopolysiloxane cured product according to claim 8.

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