Silicone composition and its cured product

Abstract

To provide a silicone composition that gives a cured article having a high storage elastic modulus under a high frequency wave condition and a low storage elastic modulus under a low frequency wave condition without using a hollow inorganic filler.SOLUTION: A silicone composition contains (A) an organopolysiloxane having at least one alkenyl group bonded to a silicon atom in one molecule and having a viscosity of 0.01-100 Pa s at 25°C: 100 pts.mass, (B) an organohydrogenpolysiloxane having at least one hydrogen atom bonded to a silicon atom in one molecule: 0.1-100 pts.mass, (C) an addition reaction catalyst, and (D) two or more solid inorganic fillers having different shapes from each other with their particle diameters being 100 μm or less on average: 10-500 pts.mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a silicone composition and its cured product. [Background technology]

[0002] In recent years, the field of electrical and electronics has seen a significant increase in the sophistication of mobile devices such as smartphones, tablets, and wearable devices. Consequently, the components used in these devices have also become smaller and more high-performance. The components mounted on these devices may be displaced due to vibrations of the terminal or damaged by strong impacts such as drops. Therefore, a method is employed to protect these components with soft materials against slow stresses such as vibrations and hard materials against fast stresses such as impacts (see Patent Document 1).

[0003] Incidentally, generally speaking, substances that have the property of changing viscoelastic properties depending on the stress frequency are liquid or grease-like compositions with a high density of particles (Patent Document 2). However, these compositions are prone to dripping and will flow out if not sealed, making it difficult to protect parts with the composition itself, and thus inconvenient to use in design.

[0004] Therefore, inventions have been made (Patent Document 3) of materials with viscoelastic properties that can protect against impacts in a solid form like rubber. However, with the miniaturization of the devices used, in order to utilize these properties even in smaller materials, there has been a need for materials with even greater changes in viscoelastic properties depending on frequency. Furthermore, it has been reported that silicone compositions containing hollow inorganic fillers yield cured products with high storage modulus under high frequency (Patent Document 4), but there was a problem that the hollow inorganic fillers could break during molding or when subjected to impact, reducing the mechanical strength of the cured product. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-74973 [Patent Document 2] Patent No. 3867898 [Patent Document 3] Japanese Patent Publication No. 2018-104615 [Patent Document 4] Japanese Patent Publication No. 2021-46464 [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention has been made in view of the above circumstances, and aims to provide a silicone composition that yields a cured product with a high storage modulus at high frequencies and a low storage modulus at low frequencies, without using hollow inorganic fillers. [Means for solving the problem]

[0007] As a result of diligent research to solve the above problems, the inventors of the present invention have found that a silicone composition containing two or more non-hollow inorganic fillers with different shapes yields a cured product with a high storage modulus at high frequencies and a low storage modulus at low frequencies, thus completing the present invention.

[0008] In other words, the present invention is 1. (A) Organopolysiloxane having an alkenyl group bonded to at least one silicon atom in one molecule, with a viscosity of 0.01 to 100 Pa·s at 25°C: 100 parts by mass, (B) Organohydrogenpolysiloxane having at least one hydrogen atom bonded to a silicon atom in one molecule: 0.1 to 100 parts by mass, (C) Addition reaction catalyst, and (D) Two or more solid inorganic fillers with an average particle size of 100 μm or less and different shapes: 10 to 500 parts by mass Silicone composition containing, 2. (E) One silicone composition comprising 1 to 100 parts by mass of an organopolysiloxane represented by the following formula (1), [ka] (In the formula, R 1 Each of these independently represents an unsubstituted or substituted monovalent hydrocarbon group with 1 to 10 carbon atoms that does not have an addition-reactive carbon-carbon bond, and R 2 Each of these independently represents an alkyl group, alkoxyalkyl group, alkenyl group, or acyl group, where n is an integer from 2 to 100, and a is an integer from 1 to 3. 3. The solid inorganic filler is one or two silicone compositions comprising one or more spherical inorganic fillers. 4. The solid inorganic filler is any of the silicone compositions 1 to 3 comprising one or more non-spherical inorganic fillers. 5. The solid inorganic filler is a silicone composition comprising any of 1 to 4, including crystalline silica and fused silica. 6. A silicone cured product obtained by curing any of the silicone compositions from 1 to 5. 7. A silicone cured product of type 6 in which the value of (storage modulus at a frequency of 100 Hz) / (storage modulus at a frequency of 0.1 Hz) is 5.0 or greater. 8. A silicone cured product of grade 6 or 7 with a hardness of 5 or higher as measured with a durometer type A. 9. Impact-absorbing material consisting of any of the silicone cured products from 6 to 8, 10.9 Electronic components with shock-absorbing material To provide. [Effects of the Invention]

[0009] By using the silicone composition of the present invention, it is possible to obtain a cured product that not only has a high storage modulus when subjected to impacts such as drops, protecting the precision components inside from impact, but also has a low storage modulus when subjected to vibrations, preventing displacement of the components. Furthermore, since the cured product of the present invention exhibits a higher change in storage modulus than conventional products, these properties can be fully expressed even with smaller materials. The cured product of the present invention having such characteristics is extremely effective for devices to be miniaturized, such as smartphones and smartwatches.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be specifically described. The silicone composition according to the present invention is (A) An organopolysiloxane having an alkenyl group bonded to at least one silicon atom in one molecule and having a viscosity at 25 °C of 0.01 to 100 Pa·s, (B) An organohydrogenpolysiloxane having a hydrogen atom bonded to at least one silicon atom in one molecule, (C) An addition reaction catalyst, (D) Two or more types of solid inorganic fillers having an average particle size of 100 μm or less and different shapes from each other and is characterized by containing them.

[0011] [1] Component (A) Component (A) is an organopolysiloxane having a viscosity at 25 °C of 0.01 to 100 Pa·s, preferably 0.1 to 10 Pa·s, more preferably 0.5 to 10 Pa·s, and having an alkenyl group bonded to at least one silicon atom in one molecule.

[0012] In the present invention, when the viscosity is less than 0.01 Pa·s, the storage stability of the composition deteriorates, and when it exceeds 100 Pa·s, the viscosity of the composition becomes high viscosity and the moldability cannot be ensured. The viscosity is a measured value by a rotational viscometer (hereinafter the same). Such an organopolysiloxane is not particularly limited as long as it satisfies the above viscosity and alkenyl group content, and known organopolysiloxanes can be used. Its structure may be linear or branched, or a mixture of two or more organopolysiloxanes having different viscosities may also be used.

[0013] The number of carbon atoms in the alkenyl group bonded to the silicon atom is not particularly limited, but is preferably 2 to 10, and more preferably 2 to 8. Specific examples of alkenyl groups include vinyl, allyl, 1-butenyl, and 1-hexenyl groups, among which the vinyl group is preferred due to its ease of synthesis and cost. The alkenyl group may be present at the end or in the middle of the organopolysiloxane molecular chain, but it is preferable that it be present only at the end for flexibility reasons.

[0014] Examples of organic groups other than alkenyl groups that bond with silicon atoms include monovalent hydrocarbon groups having 1 to 20 carbon atoms, preferably 1 to 10. Specific examples of such monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-hexyl, and n-dodecyl groups; aryl groups such as phenyl groups; and aralkyl groups such as 2-phenylethyl and 2-phenylpropyl groups. Furthermore, some or all of the hydrogen atoms in these hydrocarbon groups may be substituted with halogen atoms such as chlorine, fluorine, or bromine. Specific examples of halogen-substituted groups include halogen-substituted monovalent hydrocarbon groups such as fluoromethyl, bromoethyl, chloromethyl, and 3,3,3-trifluoropropyl. Among these, it is preferable that 90 mol% or more of the above organic groups are methyl groups, considering ease of synthesis and cost.

[0015] Based on the above, as component (A), an organopolysiloxane in which both ends are sealed with dimethylvinylsilyl groups is preferred, and in particular, a dimethylpolysiloxane in which both ends are sealed with dimethylvinylsilyl groups is more preferred. Furthermore, component (A) may be used alone or in combination of two or more types.

[0016] [2](B) Component Component (B) is an organohydrogenpolysiloxane having at least one hydrogen atom bonded to a silicon atom in each molecule. The molecular structure of component (B), the organohydrogensiloxane, may be linear, branched, or network-like. Its kinematic viscosity is also not particularly limited, but it should be between 1 and 10,000 mmHg at 25°C. 2 / s is preferred, and 1 to 1,000 mm 2 / s is more preferable. Note that the kinematic viscosity was measured using a Cannon-Fenske viscometer.

[0017] (B) The organic groups other than the hydrogen atoms bonded to the silicon atoms are preferably those with 1 to 10 carbon atoms, excluding alkenyl groups. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-hexyl, and n-dodecyl groups; aryl groups such as phenyl groups; and aralkyl groups such as 2-phenylethyl and 2-phenylpropyl groups. Some or all of the hydrogen atoms in these hydrocarbon groups may be substituted with halogen atoms such as chlorine, fluorine, or bromine. Specific examples of halogen-substituted groups include halogen-substituted monovalent hydrocarbon groups such as fluoromethyl, bromoethyl, chloromethyl, and 3,3,3-trifluoropropyl groups. Among these, it is preferable that 90 mol% or more of the above organic groups are methyl groups, considering ease of synthesis and cost.

[0018] In particular, the (B) component of the present invention preferably includes an organohydrogenpolysiloxane represented by the following formula (2).

[0019] [ka] (In the formula, the sequence of siloxane units enclosed in parentheses may be arbitrary.)

[0020] In equation (2), p and q are positive integers, and p+q represents an integer between 10 and 100, preferably between 20 and 60. When the value of p+q is within this range, the organohydrogenpolysiloxane has a viscosity suitable for handling, and when used in electronic components, it can suppress contact failures caused by the volatilization of the organohydrogenpolysiloxane. Furthermore, p / (p+q) is preferably 0.01 to 0.5, and more preferably 0.05 to 0.4. Within this range, crosslinking proceeds sufficiently, and the excess crosslinking reaction by unreacted Si-H groups after initial curing is suppressed over time.

[0021] The above R 3 Each of these independently represents an alkyl group having 1 to 6 carbon atoms, and its structure can be linear, branched, or cyclic. Specific examples of alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, and n-hexyl groups, and R is chosen in terms of ease of synthesis and cost. 3 Preferably, 90 mol% or more of the compound consists of methyl groups.

[0022] Furthermore, it is preferable that component (B) of the present invention includes an organohydrogenpolysiloxane represented by the following formula (3).

[0023] [ka]

[0024] In equation (3), R 4 Each of these independently represents an alkyl group having 1 to 6 carbon atoms, and a specific example is the above R 3 Similar groups to those exemplified above can be cited, but in this case as well, methyl groups are preferred to account for 90% or more due to ease of synthesis and cost. Furthermore, m represents an integer between 5 and 1,000, but is preferably an integer between 10 and 100. Within this range, the organohydrogenpolysiloxane has a viscosity suitable for handling, and when used in electronic components, it can suppress contact failures caused by the volatilization of the organohydrogenpolysiloxane.

[0025] A suitable example of component (B) used in the present invention is, but is not limited to, the organohydrogenpolysiloxane represented by the following formula.

[0026] [ka] (In the formula, the sequence of siloxane units enclosed in parentheses is arbitrary.)

[0027] The amount of component (B) is 0.1 to 100 parts by mass per 100 parts by mass of organopolysiloxane (A), but 1 to 10 parts by mass is preferred, taking into consideration the curability of the composition. Furthermore, component (B) may be used alone or in combination of two or more types.

[0028] [3](C) component The addition reaction catalyst for component (C) is a platinum group metal catalyst that promotes the addition reaction between the alkenyl group of component (A) and the Si-H group of component (B). It can be appropriately selected from conventionally known catalysts. Specific examples of catalysts include elemental platinum group metals such as platinum (including platinum black), rhodium, and palladium; platinum chloride, chloroplatinic acid, and chloroplatinate salts such as H2PtCl4·nH2O, H2PtCl6·nH2O, NaHPtCl6·nH2O, KHPtCl6·nH2O, Na2PtCl6·nH2O, K2PtCl4·nH2O, PtCl4·nH2O, PtCl2, and Na2HPtCl4·nH2O (where n is an integer from 0 to 6, preferably 0 or 6); and alcohols. Examples include modified chloroplatinic acid; complexes of chloroplatinic acid and olefins; catalysts in which platinum group metals such as platinum black and palladium are supported on a carrier such as alumina, silica, or carbon; rhodium-olefin complexes; chlorotris(triphenylphosphine)rhodium (Wilkinson catalyst); and complexes of platinum chloride, chloroplatinic acid, or chloroplatinate salts with vinyl group-containing siloxanes. These platinum group metal catalysts may be used individually or in combination of two or more types. Among these, catalysts selected from platinum and platinum compounds are preferred.

[0029] The amount of component (C) should be an effective amount as a catalyst, that is, an amount that can carry out the reaction between component (A), etc. and component (B), and should be adjusted as appropriate according to the desired curing speed. In particular, the amount of component (A) should be 0.1 to 7,000 ppm, preferably 1 to 6,000 ppm, based on the mass of platinum group metal atoms. If the amount of component (C) is less than 0.1 ppm based on the mass of platinum group metal atoms, the catalytic effect may not be exhibited, and even if it is used in amounts exceeding 7,000 ppm, no particular improvement in curing speed can be expected.

[0030] [4](D) component Component (D) consists of two or more solid inorganic fillers of different shapes with an average particle size of 100 μm or less, and is also a component that increases the storage modulus at high frequencies. The average particle diameter of the inorganic filler is 100 μm or less from the viewpoint of the impact protection performance of the cured product. Considering enhancing this impact protection performance further, 1 to 90 μm is preferable, and 1 to 80 μm is more preferable. In addition, the average particle diameter in the present invention is D in the volume-based particle size distribution by the laser light diffraction method 50 (that is, the particle diameter or median diameter when the cumulative volume becomes 50%) and is a measured value.

[0031] In the present invention, it is important to use a combination of inorganic fillers having different shapes. In particular, it preferably includes a combination of spherical and non-spherical shapes, and more preferably includes a combination of spherical and crystalline shapes. Regarding the combination of inorganic fillers, any number of two or more types having different shapes may be used, and inorganic fillers of different components may be combined. However, considering the uniformity of the composition and changes over time, it is preferable to use an inorganic filler composed of a single component. Also, the true specific gravity of the inorganic filler is not particularly limited, but considering the ease of preparing the composition and simultaneously achieving weight reduction, 0.1 to 3.0 is preferable.

[0032] Specific examples of the component (D) include metal oxides such as silica, alumina, and titanium oxide. Among these, silica and alumina are preferable because they are easily available and have excellent filling properties into silicone.

[0033] The blending amount of the component (D) is 10 to 500 parts by mass with respect to 100 parts by mass of the organopolysiloxane of the component (A). When the blending amount is less than 10 parts by mass, the effect of impact protection of the composition may not be sufficiently obtained. When it exceeds 500 parts by mass, the mechanical properties of the composition are inferior.

[0034] [5] Component (E) The silicone composition of the present invention may contain an organopolysiloxane represented by the following formula (1) as the component (E). This component (E) serves to lower the viscosity of the composition Solid inorganic and improve the filling property of the filler.

[0035] [ka]

[0036] In equation (1), R 1 Each of these is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6, more preferably 1 to 3, that does not have an addition-reactive carbon-carbon bond. Examples of this monovalent hydrocarbon group include linear, branched, or cyclic alkyl groups, aryl groups, aralkyl groups, and alkyl halogens. Specific examples of linear alkyl groups include methyl, ethyl, n-propyl, n-hexyl, and n-octyl groups. Specific examples of branched alkyl groups include isopropyl, isobutyl, tert-butyl, and 2-ethylhexyl groups. Specific examples of cyclic alkyl groups include cyclopentyl and cyclohexyl groups. Specific examples of aryl groups include phenyl and tolyl groups. Specific examples of aralkyl groups include 2-phenylethyl and 2-methyl-2-phenylethyl groups. Specific examples of alkyl halides include 3,3,3-trifluoropropyl, 2-(nonafluorobutyl)ethyl, and 2-(heptadecafluorooctyl)ethyl groups. Among these, R 1 The group is preferably a linear alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group.

[0037] Also, R 2 These are, independently of each other, alkyl groups, alkoxyalkyl groups, alkenyl groups, or acyl groups having 1 to 5 carbon atoms. Specific examples of alkyl groups include those exemplified in R1 above. Specific examples of alkoxyalkyl groups include methoxyethyl and methoxypropyl groups. Specific examples of acyl groups include acetyl and octanoyl groups. Among these, R 2 The group is preferably a linear alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group. Furthermore, n represents an integer between 2 and 100, but is preferably an integer between 5 and 80. a is an integer between 1 and 3, but is preferably 3.

[0038] The viscosity of component (E) at 25°C is not particularly limited, but from the viewpoint of preventing bleeding from the composition and moldability, it is preferably 0.005 to 10 Pa·s, and more preferably 0.005 to 1 Pa·s.

[0039] (E) Suitable specific examples of component include, but are not limited to, organopolysiloxanes represented by the following formula.

[0040] [ka]

[0041] When using component (E), the amount to be blended is preferably 1 to 100 parts by mass, more preferably 1 to 50 parts by mass, per 100 parts by mass of component (A), from the viewpoint of curability. Furthermore, component (E) may be used alone or in combination of two or more types.

[0042] [6] Other ingredients The silicone composition of the present invention may contain known additives in addition to the above components (A) to (E), to the extent that they do not impair the purpose of the present invention. Examples of such additives include reaction regulators, hindered phenol antioxidants, fillers such as calcium carbonate, pigments, and dyes. As a reaction control agent, any agent that can suppress the catalytic activity of component (C) in order to suppress the curing reaction at room temperature and extend the shelf life and pot life is acceptable, and can be appropriately selected from known reaction control agents. Specific examples of reaction control agents include acetylene compounds having hydroxyl groups such as 1-ethynyl-1-cyclohexanol and 3-butyne-1-ol, various nitrogen compounds, organophosphorus compounds, oxime compounds, and organochloro compounds. Among these, acetylene compounds having hydroxyl groups that are not corrosive to metals are preferred. Furthermore, the reaction control agent may be diluted with an organic solvent such as toluene, xylene, or isopropyl alcohol to improve its dispersibility in the silicone resin.

[0043] [7] Method for producing a silicone composition The method for producing the silicone composition of the present invention is not particularly limited and may follow conventionally known methods. That is, the silicone composition of the present invention can be obtained by mixing components (A) to (D), and component (E) and other components which may be used as needed.

[0044] More specifically, a one-component composition can be obtained by placing components (A), (D), and optionally (E) into a gate mixer, mixing under reduced pressure at a predetermined temperature (e.g., 25°C) for a predetermined time (e.g., 1 hour), cooling the resulting mixture, adding component (C) and a reaction control agent, mixing at a predetermined temperature (e.g., 25°C) for a predetermined time (e.g., 1 hour), and then adding component (B) and mixing at a predetermined temperature (e.g., 25°C) for a predetermined time (e.g., 30 minutes). A two-component composition can be made up of any combination of components, as long as the combination of components (A), (B), and (C) is not present together. For example, by placing components (A), (D), and optionally (E) into a gate mixer, mixing under reduced pressure at a predetermined temperature (e.g., 25°C) for a predetermined time (e.g., 1 hour), cooling, adding component (C), and mixing at a predetermined temperature (e.g., 25°C) for a predetermined time (e.g., 30 minutes), the resulting composition can be designated as material A. On the other hand, by placing components (A), (D), and optionally (E) into a gate mixer, mixing under reduced pressure at a predetermined temperature (e.g., 150°C) for a predetermined time (e.g., 1 hour), cooling, adding a reaction control agent, mixing at a predetermined temperature (e.g., 25°C) for a predetermined time (e.g., 30 minutes), then adding component (B), and mixing at a predetermined temperature (e.g., 25°C) for a predetermined time (e.g., 30 minutes), the resulting composition can be designated as material B. Thus, a two-component composition of material A and material B can be obtained. Furthermore, the silicone composition of the present invention can be stored for a long period of time by refrigeration or freezing if it is a one-component type, and can be stored for a long period of time at room temperature if it is a two-component type.

[0045] The viscosity of the silicone composition of the present invention is not particularly limited, but from the viewpoint of dispersibility of the inorganic filler and handling of the silicone composition, it is preferably 1 to 400 Pa·s at 25°C, and more preferably 10 to 300 Pa·s.

[0046] [8] Silicone cured product The cured product of the present invention is obtained by curing the silicone composition of the present invention described above. In this case, the curing conditions are not particularly limited and can be the same as those for conventionally known curable silicone compositions. Specifically, the silicone composition may be cured naturally by the heat generated from the installed parts after being poured, or it may be actively heated to cure. When curing by heating, the conditions are preferably a temperature of 60 to 180°C, more preferably 80 to 150°C, for 0.1 to 3 hours, more preferably 0.5 to 2 hours. The cured silicone composition obtained in this way typically exhibits soft behavior under slow deformation, minimizing stress on contacting parts, if its hardness, as measured by a Type A durometer specified in JIS K 6253-3:2012, is 40 or less.

[0047] In the above-mentioned cured product, the storage modulus at a frequency of 100 Hz is preferably 2.0 MPa or higher, and more preferably 2.0 to 5.0 MPa. Furthermore, the storage modulus at a frequency of 0.1 Hz is preferably less than 1.0 MPa, and more preferably 0.4 MPa or more and less than 1.0 MPa. Furthermore, the storage modulus of the cured material at a frequency of 100 Hz divided by the storage modulus at a frequency of 0.1 Hz is preferably 5.0 or higher, and more preferably 5.5 or higher. Within this range, it is suitable as an impact-absorbing material. Moreover, from the viewpoint of protecting parts from impact, the hardness measured with a Type A durometer is preferably 5 or higher, and more preferably 10 or higher. [Examples]

[0048] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The components used are listed below.

[0049] (A) component A-1: Dimethylpolysiloxane with both ends sealed with dimethylvinylsilyl groups and a viscosity of 5 Pa·s at 25°C. A-2: Dimethylpolysiloxane with both ends sealed with dimethylvinylsilyl groups and a viscosity of 1 Pa·s at 25°C.

[0050] (B) Component B-1: Organohydrogensiloxane represented by the following formula [ka]

[0051] B-2: Organohydrogensiloxane represented by the following formula [ka] (In the formula, the sequence of siloxane units enclosed in parentheses is arbitrary.)

[0052] (C) Component • C-1: Dimethylpolysiloxane solution of platinum-divinyltetramethyldisiloxane complex (dissolved in the same dimethylpolysiloxane as A-2 above. Contains 1% platinum atoms)

[0053] (D) Component D-1: Fused (spherical) silica with an average particle size of 5 μm. D-2: Crystalline (non-spherical) silica with an average particle size of 4 μm. • D-3: Crystalline (non-spherical) silica with an average particle size of 6 μm. D-4: Fused (spherical) silica with an average particle size of 15 μm. D-5: Spherical alumina with an average particle size of 3 μm D-6: Crushed (non-spherical) alumina with an average particle size of 1 μm.

[0054] (E) Component • E-1: Organopolysiloxane represented by the following formula [ka]

[0055] Other ingredients · F-1: 1-ethynyl-1-cyclohexanol

[0056] [Example 1~ 6 [and Comparative Examples 1-3] Components (A), (D), and (E) were added to a 5L gate mixer (manufactured by Inoue Seisakusho Co., Ltd., 5L planetary mixer) and mixed under reduced pressure at 25°C for 1 hour. Next, component (C) was added and mixed at 25°C for 30 minutes. Then, the reaction control agent (F-1) was added and mixed at 25°C for 30 minutes. Finally, component (B) was added and mixed at 25°C for 30 minutes. The amounts of each component are shown in Table 1.

[0057] The following physical properties were measured and evaluated for the cured products obtained by curing each of the compositions described above. The results are shown in Table 1. (1)Hardness Each silicone composition was pressed and cured at 120°C for 10 minutes to a thickness of 2.0 mm, and then heated in an oven at 120°C for 50 minutes. Three of the resulting silicone sheets were stacked together, and their hardness was measured using a Type A durometer as specified in JIS K 6253-3:2012. (2) Storage modulus Each silicone composition was press-cured to a thickness of 2.0 mm at 120°C for 10 minutes, and then heated in an oven at 120°C for 50 minutes. The resulting silicone sheets were measured for viscoelasticity using Rheogel-E4000 manufactured by UBM Co., Ltd., in tensile mode and sinusoidal strain, and the storage modulus at a frequency of 0.1 Hz and 100 Hz were evaluated.

[0058] [Table 1]

[0059] As shown in Table 1, the cured products obtained by curing the silicone compositions obtained in Examples 1 to 6 have relatively high values ​​of (storage modulus at a frequency of 100 Hz) / (storage modulus at a frequency of 0.1 Hz), ranging from 5.5 to 7.5, indicating that they possess good properties.

Claims

1. (A) Organopolysiloxane having an alkenyl group bonded to at least one silicon atom in one molecule, with a viscosity of 0.01 to 100 Pa·s at 25°C: 100 parts by mass, (B) Organohydrogenpolysiloxane having at least one hydrogen atom bonded to a silicon atom in one molecule: 0.1 to 100 parts by mass, (C) Addition reaction catalyst, and (D) Two or more solid inorganic fillers with an average particle size of 100 μm or less and different shapes from one another: 10 to 500 parts by mass A silicone composition comprising, The solid inorganic filler comprises one or more spherical inorganic fillers and one or more non-spherical inorganic fillers. The spherical inorganic filler is contained in an amount of 280 to 315 parts by mass per 100 parts by mass of component (A). The non-spherical inorganic filler is present in an amount of 35 to 70 parts by mass per 100 parts by mass of component (A), A silicone composition in which the spherical inorganic filler and the non-spherical inorganic filler are a combination of fused silica and crystalline silica.

2. (E) The silicone composition according to claim 1, comprising 1 to 100 parts by mass of an organopolysiloxane represented by the following formula (1). 【Chemistry 1】 (In the formula, R 1 Each of these independently represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms that does not have an addition-reactive carbon-carbon bond, and R 2 Each of these independently represents an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group; n represents an integer from 2 to 100; and a represents an integer from 1 to 3.

3. A cured silicone product obtained by curing the silicone composition according to claim 1 or 2.

4. The silicone cured product according to claim 3, wherein the value of (storage modulus at a frequency of 100 Hz) / (storage modulus at a frequency of 0.1 Hz) is 5.0 or greater.

5. A silicone cured product according to claim 3 or 4, wherein the hardness measured with a durometer type A is 5 or higher.

6. An impact cushioning material comprising a silicone cured product according to any one of claims 3 to 5.

7. An electronic component having the shock-absorbing material described in claim 6.

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