CURABLE LIQUID SILICONE COMPOSITION, CURED PRODUCT THEREOF, OPTICAL FILLER CONTAINING THE SAME, AND DISPLAY DEVICE COMPRISING A LAYER MADE OF THE CURED PRODUCT

Abstract

[Problem] To provide: a photocurable liquid silicone composition that has a low viscosity that allows for easy injection, even into small gaps, has a high refractive index in both the visible and infrared ranges after being cured, and is particularly useful as a material for use in devices that use an infrared LED light source; and a use for the photocurable liquid silicone composition. [Solution] A curable liquid silicone composition that includes (A) (A1) an organosilane or organopolysiloxane that has 1–5 silicon atoms, an alkenyl group, and at least one monovalent functional group selected from among aromatic groups and aralkyl groups and / or (A2) an organopolysiloxane that has 2–5 silicon atoms and an alkenyl group but does not have a monovalent functional group selected from among aromatic groups and aralkyl groups, (C) a compound that has at least two silicon-bonded hydrogen atoms, and (D) a hydrosilylation reaction catalyst, the overall refractive index of the liquid composition before curing being at least 1.47, and the overall viscosity of the liquid composition before curing being no more than 500 mPa·s.

Description

[Technical field]

[0001] The present invention relates to a curable liquid silicone composition that can be cured by heat treatment, has a low viscosity suitable for use in injection molding, and gives a cured product with a high refractive index, and to the cured product and its uses. The curable liquid silicone composition of the present invention has a high refractive index and transparency, and is suitable as a material for forming light-transmitting layers for electronic / electrical devices and optical devices. [Background technology]

[0002] Electronic / electrical devices and optical devices using white and ultraviolet LEDs as light sources have been widely put to practical use. Silicone materials are being actively studied as peripheral materials because of the need for high transparency and reliability. As a liquid sealing material that directly seals a light source, for example, a high refractive index liquid silicone composition as disclosed in Patent Document 1 has already been put to practical use. In addition, infrared LED light sources and devices using them are being actively developed with an eye on the large market for various sensors, surveillance cameras, infrared data communications, etc. Meanwhile, in addition to these conventional LEDs, micro LED technology that takes advantage of its high energy efficiency has been rapidly researched and developed, and is beginning to be applied to various uses.

[0003] Here, in the case of micro LEDs, which have been studied in recent years, the size of the light source substrate is very small, so the surrounding materials are often required to be small in area and thin. In this case, the injection molding method, in which a curable composition is injected into the gap between the light source substrate and the transparent substrate and cured, is considered to be promising as a method for forming a sealing layer between the light source substrate and the transparent substrate. As a material suitable for this processing method, a low-viscosity liquid silicone material that can be quickly cured and has high transparency after curing is required. Furthermore, a material with a high refractive index is desired to reduce interface reflection and increase light extraction efficiency.

[0004] However, the conventionally known high refractive index liquid silicone composition has a high overall viscosity, and when applied to the injection molding method, it may not be possible to inject it into a small gap between members (hereinafter, sometimes referred to as "small gap"), or may not be able to achieve sufficient gap filling. For example, the curable liquid silicone composition disclosed in the above Patent Document 1 has a very high overall viscosity of 3,000 mPas or more at 25°C, and cannot be used in the injection molding method. Specifically, even if such a high-viscosity curable liquid silicone composition is injected between a light source substrate and a transparent substrate to seal them, it is difficult to inject it so as to sufficiently fill the gap between them, which may cause defects and sealing failures in the process, and this is undesirable as it causes a decrease in production efficiency and yield, a decrease in quality, and a failure of the final display device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-008996 A (Patent No. 5392805 A) Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to provide a curable liquid silicone composition which has a low viscosity enabling it to be easily injected into small gaps, which cures rapidly when held at room temperature or when subjected to heat treatment, and which has a high refractive index after curing not only in the visible region but also in the infrared region, and which is particularly useful as a material for devices using infrared LED light sources; a cured product thereof; and uses of the same. [Means for solving the problem]

[0007] The curable liquid silicone composition of the present invention comprises: (A) One or more organosilicon compounds selected from the following components (A1) and (A2): (A1) an organosilane or organopolysiloxane having 1 to 5 silicon atoms, at least two alkenyl groups having 2 to 12 carbon atoms in one molecule, and further having at least one monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms; (A2) a linear or branched organopolysiloxane having 2 to 5 silicon atoms, at least two alkenyl groups having 2 to 12 carbon atoms in one molecule, and no monovalent functional group selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms, and having a boiling point of 180°C or higher under normal pressure; (C) a compound having at least two silicon-bonded hydrogen atoms per molecule {an amount such that the number of silicon-bonded hydrogen atoms in this component is 0.2 to 3 moles per mole of the total number of alkenyl groups in the composition}, and (D) a catalyst for hydrosilylation reaction The liquid composition as a whole before curing has a refractive index of 1.47 or more at 25°C and a wavelength of 847 nm, and has a viscosity of 500 mPa·s or less as measured at 25°C using an E-type viscometer. Here, the viscosity of the entire liquid composition as measured at 25°C using an E-type viscometer is preferably 200 mPa·s or less, and particularly preferably in the range of 3 to 175 mPa·s.

[0008] The cured product of the present invention is characterized by being produced by curing the above-mentioned curable liquid silicone composition.

[0009] The optical filler of the present invention is characterized by containing the above-mentioned curable liquid silicone composition.

[0010] The display device of the present invention is characterized by including a layer made of a cured product of the above-mentioned curable liquid silicone composition.

[0011] The curable liquid silicone composition of the present invention can be suitably used in the manufacture of a display device, particularly a display device using an infrared LED light source. That is, the method of manufacturing a display device of the present invention includes a step of injecting the above-mentioned curable liquid silicone composition between a light source substrate and a transparent substrate, and a step of curing the injected curable liquid silicone composition by heating. Effect of the Invention

[0012] The curable liquid silicone composition of the present invention has a low viscosity that allows it to be easily injected into small gaps, and it cures quickly when left at room temperature or when heated. In addition, the refractive index after curing is high not only in the visible region but also in the infrared region, making it useful as a material for devices using infrared LED light sources. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] First, the curable liquid silicone composition of the present invention will be described in detail. Component (A) is one of the characteristic components of the present composition, and is a component that reduces the viscosity of the curable liquid silicone composition without impairing its curability, and is one or more organosilicon compounds selected from components (A1) and (A2) below. Component (A) is characterized by its low volatility and by not inhibiting the curing of the composition of the present invention. (A1) an organosilane or organopolysiloxane having 1 to 5 silicon atoms, at least two alkenyl groups having 2 to 12 carbon atoms in one molecule, and further having at least one monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms; (A2) A linear or branched organopolysiloxane having 2 to 5 silicon atoms, at least two alkenyl groups having 2 to 12 carbon atoms in one molecule, and no monovalent functional group selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms, and having a boiling point of 180°C or higher under normal pressure.

[0014] Since the component (A) has 5 or less silicon atoms, it is a silane or siloxane oligomer (a polysiloxane with a degree of siloxane polymerization of 5 or less) with a small molecular weight, and has at least two alkenyl groups with 2 to 12 carbon atoms in the molecule that participate in the curing reaction, so that a crosslinking reaction proceeds with the component (C) described below. On the other hand, from the scope of the component (A), components that do not improve the refractive index and may adversely affect the curing reaction, such as methylsiloxane that has an alkenyl group such as a vinyl group but does not have an aromatic group or an aralkyl group and has a cyclic structure, are excluded. Such a component (A) has the properties of being a relatively low molecular weight and low viscosity component, yet being low volatility and not easily inhibiting the curing reaction. Therefore, the composition of the present invention containing the component (A) has excellent curing reactivity, and can reduce the viscosity of the entire composition suitable for injection molding, thereby significantly improving the gap filling property.

[0015] Component (A) may or may not contain a monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms within the molecule; however, the presence of such an aromatic group or aralkyl group makes it possible to improve the refractive index of the liquid silicone composition before curing, and of the cured product thereof, as described below, and therefore it is preferable to use a component containing such a functional group as at least a part of component (A).

[0016] Specifically, the component (A) is one or more organosilicon compounds selected from the following components (A1) and (A2). (A1) an organosilane or organopolysiloxane having 1 to 5 silicon atoms, at least two alkenyl groups having 2 to 12 carbon atoms in one molecule, and further having at least one monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms; (A2) A linear or branched organopolysiloxane having 2 to 5 silicon atoms, at least two alkenyl groups having 2 to 12 carbon atoms in one molecule, and no monovalent functional group selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms, and having a boiling point of 180°C or higher under normal pressure.

[0017] Here, the number of silicon atoms in component (A1) is 1 to 5, and the number of silicon atoms in component (A2) is 2 to 5, but the number of silicon atoms in component (A1) or component (A2) is preferably in the range of 2 to 5, and may be and is preferably 2, 3, or 4. This can increase the contribution to lowering the viscosity of the curable composition.

[0018] Examples of alkenyl groups in component (A) include vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl groups, of which vinyl, allyl, 5-hexenyl, and 7-octenyl groups are preferred from the standpoint of economy and reactivity, which is the same for components (A1) and (A2).

[0019] The component (A1) has, in addition to the alkenyl group, at least one monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms in the molecule. Examples of these functional groups include aryl groups having 6 to 12 carbon atoms, such as phenyl, tolyl, and xylyl; and aralkyl groups having 7 to 12 carbon atoms, such as benzyl and phenethyl. From the viewpoint of economy, phenyl and phenethyl groups are preferred.

[0020] On the other hand, examples of other groups bonded to silicon atoms in component (A) (specifically, groups other than monovalent functional groups selected from the above-mentioned alkenyl groups, aromatic groups having 6 to 12 carbon atoms, and aralkyl groups having 7 to 12 carbon atoms) include alkyl groups having 1 to 12 carbon atoms such as methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups, heptyl groups, octyl groups, nonyl groups, decyl groups, undecyl groups, and dodecyl groups; and halogen-substituted alkyl groups having 1 to 12 carbon atoms such as 3-chloropropyl groups and 3,3,3-trifluoropropyl groups, of which methyl groups are preferred from the viewpoints of economy and heat resistance. In addition, a small amount of alkoxy groups such as methoxy groups, ethoxy groups, n-propoxy groups, i-propoxy groups, n-butoxy groups, sec-butoxy groups, and tert-butoxy groups, and hydroxyl groups may be bonded to silicon atoms in component (A). This is common to components (A1) and (A2).

[0021] Specifically, examples of the component (A1) in the present invention include the following compounds A1-1 to A1-13. A1-1: Divinyldiphenylsilane A1-2: 1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane A1-3: 1,5-divinyl-3,3-diphenyl-1,1,5,5-tetramethyltrisiloxane A1-4: 1,5-divinyl-1,5-diphenyl-1,3,3,5-tetramethyltrisiloxane A1-5: 1,5-diphenyl-3,3-divinyl-1,1,5,5-tetramethyltrisiloxane A1-6: 1,5-diphenethyl-3,3-divinyl-1,1,5,5-tetramethyltrisiloxane A1-7: 1,7-divinyl-3,3,5,5-tetraphenyl-1,1,7,7-tetramethyltetrasiloxane A1-8: 1,7-divinyl-1,7-diphenyl-1,3,3,5,5,7-hexamethyltetrasiloxane A1-9: 1,7-divinyl-3,3-diphenyl-1,1,5,5,7,7-hexamethyltetrasiloxane A1-10: 1,7-divinyl-3,5-diphenyl-1,1,3,5,7,7-hexamethyltetrasiloxane A1-11: 1,3-divinyl-5,7-diphenyl-1,3,5,7-tetramethylcyclotetrasiloxane A1-12: 1,5-divinyl-3,7-diphenyl-1,3,5,7-tetramethylcyclotetrasiloxane A1-13: Phenyl-tris(dimethylvinylsiloxy)silane

[0022] Specifically, examples of the component (A2) in the present invention include the following compounds A2-1 to A2-9. A2-1: 1,3-di(3-butenyl)-1,1,3,3-tetramethyldisiloxane A2-2: 1,3-di(5-hexenyl)-1,1,3,3-tetramethyldisiloxane A2-3: 1,3-di(7-octenyl)-1,1,3,3-tetramethyldisiloxane A2-4: 1,5-divinyl-1,1,3,3,5,5-hexamethyltrisiloxane A2-5: 1,5-di(3-butenyl)-1,1,3,3,5,5-hexamethyltrisiloxane A2-6: 1,5-di(5-hexenyl)-1,1,3,3,5,5-hexamethyltrisiloxane A2-7: 1,5-di(7-octenyl)-1,1,3,3,5,5-hexamethyltrisiloxane A2-8: Methyl-tris(dimethylvinylsiloxy)silane A2-9: Tetrakis(dimethylvinylsiloxy)silane

[0023] The content of component (A) is not limited as long as the viscosity of the entire liquid composition of the curable liquid silicone composition of the present invention measured at 25°C using an E-type viscometer is 500 mPa·s or less, but in order to design within this viscosity range, when the total amount of the above component (A) and the below-described components (C), (D) and (B) is taken as 100 parts by mass, an appropriate content is 5 to 99 parts by mass, a preferred content is 5 to 80 parts by mass, and a more preferred content is 5 to 60 parts by mass. This is because when the content of component (A) is at or above the lower limit of the above range, it is easy to reduce the viscosity of the resulting curable composition, while when it is at or below the upper limit of the above range, the mechanical properties of the resulting cured product are improved.

[0024] In the curable liquid silicone composition of the present invention, either one of the (A1) component and the (A2) component can be used as the (A) component, or both can be used together. Here, from the viewpoint of increasing the refractive index of the curable liquid silicone composition and its cured product, the use of the (A1) component is advantageous, while in order to efficiently reduce the overall viscosity of the liquid composition, the use of the (A2) component is advantageous. Therefore, it is preferable to use the (A1) component or the (A2) component alone, or to appropriately design the blending ratio of the two, depending on the desired properties such as the refractive index and viscosity of the curable liquid silicone composition of the present invention.

[0025] When component (A2) is a linear or branched organopolysiloxane (=siloxane oligomer) that does not have a monovalent functional group selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms, the use of component (B) described below is particularly preferred, because the use of component (A) alone can make it difficult to design the refractive index of the entire liquid composition before curing to 1.47 or more at 25°C and a wavelength of 847 nm.

[0026] Component (B) is an optional component of the curable liquid silicone composition of the present invention, and is an organopolysiloxane having an average of more than 5 silicon atoms in one molecule, at least one alkenyl group having 2 to 12 carbon atoms, and at least 34 mol% of the number of substituents on the silicon atoms being monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms. Since component (B) contains many aromatic groups or aralkyl groups in the molecule, it efficiently improves the refractive index of the entire composition and its cured product. Component (B) also preferably has at least two alkenyl groups having 2 to 12 carbon atoms in the molecule, and particularly preferably has alkenyl groups having 2 to 12 carbon atoms at both ends of the molecular chain.

[0027] Examples of the alkenyl group in component (B) include vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl groups, with vinyl, allyl, 5-hexenyl, and 7-octenyl being preferred from the standpoint of economy and reactivity. Examples of groups bonded to silicon atoms other than the alkenyl group in component (B) include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups; and halogen-substituted alkyl groups having 1 to 12 carbon atoms, such as 3-chloropropyl and 3,3,3-trifluoropropyl groups, with methyl being preferred from the standpoint of economy and heat resistance. On the other hand, examples of monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms include aryl groups having 6 to 12 carbon atoms, such as phenyl, tolyl, and xylyl, and aralkyl groups having 7 to 12 carbon atoms, such as benzyl and phenethyl, with phenyl and phenethyl being preferred from the viewpoint of economy. A small amount of alkoxy groups, such as methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, sec-butoxy, and tert-butoxy, or hydroxyl groups may be bonded to the silicon atoms in component (B).

[0028] There is no limitation on the viscosity of component (B) at 25°C, but it is within the range of 50 to 100,000 mPa·s, and preferably within the range of 100 to 100,000 mPa·s, 100 to 50,000 mPa·s, or 100 to 10,000 mPa·s. This is because when the viscosity of component (B) is at or above the lower limit of the above range, the mechanical properties of the resulting cured product are improved, whereas when it is at or below the upper limit of the above range, it is easy to reduce the viscosity of the resulting curable composition. It is a linear polysiloxane represented by the following formula (1). [ka] (1) In the formula, R 1 are the same or different alkenyl groups (terminal alkenyl groups) having 2 to 12 carbon atoms, examples of which include vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl groups, of which vinyl, allyl, 5-hexenyl, and 7-octenyl groups are preferred from the standpoints of economy and reactivity. R 2 and R 3 each independently represents an unsubstituted or fluorine-substituted monovalent alkyl group having 1 to 12 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a 3-chloropropyl group, and a 3,3,3-trifluoropropyl group. From the viewpoints of economy and heat resistance, a methyl group is preferred. R 4 are each independently a monovalent functional group selected from unsubstituted or fluorine-substituted aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms, and examples thereof include a phenyl group, a tolyl group, a xylyl group, a benzyl group, and a phenethyl group, with a phenyl group and a phenethyl group being preferred from the viewpoint of economy. R 5 and R 6are each independently a monovalent functional group selected from an unsubstituted or fluorine-substituted monovalent alkyl group having 1 to 10 carbon atoms, an aromatic group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms, and each is exemplified by the same groups as those exemplified above, but examples thereof include a methyl group, a phenyl group, a tolyl group, a xylyl group, a benzyl group, and a phenethyl group, and from the viewpoint of economy, a group selected from a methyl group, a phenyl group, and a phenethyl group is preferred. However, in one molecule, the substituents on the silicon atoms, i.e., all R 1 ~R 6 At least 34% of the number of monovalent functional groups selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms. Additionally, m and n in the formula are numbers that satisfy 0≦m<1,000, 0≦n<500, and 3≦m+n<1,500.

[0029] Examples of such component (B) include one or a mixture of two or more organopolysiloxanes represented by the following general formula: In the formula, Me, Vi, and Ph represent methyl, vinyl, and phenyl groups, respectively, and a and b are each preferably an integer of 1 or greater such that the viscosity at 25°C is in the range of 50 to 100,000 mPa s. Here, the value of a+b is 3 or greater, and c is a number of 3 or greater such that the viscosity at 25°C is in the range of 50 to 100,000 mPa s. Me2ViSiO(Me2SiO) a (MePhSiO) b SiMe2Vi Me2ViSiO(Me2SiO) a (Ph2SiO) b SiMe2Vi Me2ViSiO(MePhSiO) a (Ph2SiO) b SiMe2Vi Me2ViSiO(MePhSiO) c SiMe2Vi Me2ViSiO(Me(PhCH2CH2)SiO) c SiMe2Vi Me2ViSiO(Ph2SiO)c SiMe2Vi

[0030] The blending amount of the (B) component is an amount such that the content of the (B) component falls within the range of 1 to 90 parts by mass, and more preferably an amount in the range of 1 to 80 parts by mass, when the total amount of the above (A) and the later-described (C), (D), and (B) components is taken as 100 parts by mass.

[0031] Component (C) is an essential component of the curable liquid silicone composition of the present invention, and is an organopolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule. Examples of groups bonded to silicon atoms other than silicon-bonded hydrogen atoms in component (C) include alkyl groups having 1 to 12 carbon atoms, such as methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups, heptyl groups, octyl groups, nonyl groups, decyl groups, undecyl groups, and dodecyl groups; aryl groups having 6 to 20 carbon atoms, such as phenyl groups, tolyl groups, and xylyl groups; aralkyl groups having 7 to 20 carbon atoms, such as benzyl groups and phenethyl groups; and halogen-substituted alkyl groups having 1 to 12 carbon atoms, such as 3-chloropropyl groups and 3,3,3-trifluoropropyl groups. From the standpoint of economy and heat resistance, methyl groups and phenyl groups are preferred. Furthermore, small amounts of alkoxy groups such as methoxy groups, ethoxy groups, n-propoxy groups, i-propoxy groups, n-butoxy groups, sec-butoxy groups, tert-butoxy groups, and hydroxyl groups may be bonded to silicon atoms in component (C) within the scope of the present invention. Note that component (C) is preferably an organopolysiloxane having at least one aryl group per molecule, as this has excellent affinity with component (A).

[0032] There are no limitations on the viscosity of component (C) at 25°C, but it is preferably in the range of 1 to 10,000 mPa s, 1 to 1,000 mPa s, or 1 to 500 mPa s. This is because when the viscosity of component (C) is at or above the lower limit of the above range, the mechanical properties of the resulting cured product are improved, whereas when it is at or below the upper limit of the above range, the transparency and handling ease of the resulting composition are improved.

[0033] The molecular structure of component (C) is not limited, and examples of the molecular structure include linear, partially branched linear, branched, cyclic, and three-dimensional network structures. Component (C) may be a single organopolysiloxane having these molecular structures, or a mixture of two or more organopolysiloxanes having these molecular structures.

[0034] Examples of such component (C) include compounds represented by the general formula (C1): R 7 3SiO(R 7 2SiO) k SiR 7 3 Linear organopolysiloxanes and / or (C2) having the average unit formula: (R 8 3SiO 1 / 2 ) v (R 8 2SiO 2 / 2 ) y (R 8 SiO 3 / 2 ) z (SiO 4 / 2 ) w Examples of branched-chain organopolysiloxanes include those represented by the following formula:

[0035] In the component (C1), R 7 R are the same or different and are a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a halogen-substituted alkyl group having 1 to 12 carbon atoms. 7 Examples of the alkyl group of R include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group. 7 Examples of the aryl group of R include a phenyl group, a tolyl group, and a xylyl group. 7 Examples of the aralkyl group of R include a benzyl group and a phenethyl group. 7 Examples of the halogen-substituted alkyl group include a 3-chloropropyl group and a 3,3,3-trifluoropropyl group. However, at least two R7 is a hydrogen atom.

[0036] Additionally, in the formula for component (C1), k is an integer of 0 or greater, and is preferably an integer such that the viscosity of component (C1) at 25°C is within the range of 1 to 10,000 mPa·s, 1 to 1,000 mPa·s, or 1 to 500 mPa·s.

[0037] Examples of such component (C1) include one or a mixture of two or more organopolysiloxanes represented by the following general formula: In the formula, Me and Ph represent a methyl group and a phenyl group, respectively, and k ’ , k ’’ are integers of 1 or greater such that the viscosity at 25°C is in the range of 1 to 10,000 mPa·s, and k''' is an integer of 2 or greater such that the viscosity at 25°C is in the range of 1 to 10,000 mPa·s. Me3SiO(Me2SiO) k’ (MeHSiO) k’’’ SiMe3 Me3SiO(MePhSiO) k’ (MeHSiO) k’’’ SiMe3 Me3SiO(Ph2SiO) k’ (MeHSiO) k’’’ SiMe3 Me3SiO(Me2SiO) k’ (Ph2SiO) k’’ (MeHSiO) k’’’ SiMe3 HMe2SiO(Me2SiO) k’ SiMe2H HMe2SiO(Ph2SiO) k’ SiMe2H HMe2SiO(Me2SiO) k’ (Ph2SiO) k’’ SiMe2H

[0038] In the component (C2), R 8are the same or different and are a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a halogen-substituted alkyl group having 1 to 12 carbon atoms, and examples thereof include the same groups as those mentioned above. However, at least two R 8 is a hydrogen atom.

[0039] In the formula of component (C2), v, y, z, and w are each a number from 0 to 1, and the sum of v, y, z, and w is 1. However, y, z, and w cannot be 0 at the same time.

[0040] Examples of such component (C2) include one or a mixture of two or more organopolysiloxanes represented by the following average unit formula: In the formula, Me and Ph represent a methyl group and a phenyl group, respectively, and v', v'', y', z', and w' are each a number of 1 or less (but do not include 0), with the proviso that the sum of v', v'', y', z', and w' is 1. (Me3SiO 1 / 2 ) v’ (MeHSiO 1 / 2 ) v’’ (MeSiO 2 / 2 ) y’ (MeSiO 3 / 2 ) z’ (Me3SiO 1 / 2 ) v’ (MeHSiO 1 / 2 ) v’’ (MeSiO 3 / 2 ) z’ (Me3SiO 1 / 2 ) v’ (MeHSiO 1 / 2 ) v’’ (SiO 4 / 2 ) w’ (MeHSiO 1 / 2 ) v’’ (MeSiO 3 / 2 ) z’ (MeHSiO 1 / 2 ) v’’ (SiO 4 / 2 )w’ (Me3SiO 1 / 2 ) v’ (MeHSiO 1 / 2 ) v’’ (MePhSiO 2 / 2 ) y’ (PhSiO 3 / 2 ) z’ (Me3SiO 1 / 2 ) v’ (MeHSiO 1 / 2 ) v’’ (PhSiO 3 / 2 ) z’ (MeHSiO 1 / 2 ) v’’ (PhSiO 3 / 2 ) z’ (MeHSiO 1 / 2 ) v’’ (MePhSiO 2 / 2 ) y’ (PhSiO 3 / 2 ) z’ (MeHSiO 1 / 2 ) v’’ (Ph2SiO 2 / 2 ) y’ (PhSiO 3 / 2 ) z’

[0041] The (C) component may be the above-mentioned (C1) or (C2) component, either alone or in combination. By using a mixture of the (C1) and (C2) components, the mechanical properties of the resulting cured product can be improved. When the (C1) and (C2) components are used in combination, the mass ratio of the (C1) and (C2) components is preferably within the range of 10:90 to 95:5, 30:70 to 95:5, or 50:50 to 95:5.

[0042] The content of component (C) is an amount such that the silicon-bonded hydrogen atoms in this component are 0.2 to 3 moles per mole of the total amount of alkenyl groups in the composition, more specifically, an amount such that the silicon-bonded hydrogen atoms in this component are within the range of 0.2 to 3 moles per mole of the total amount of alkenyl groups (aliphatic unsaturated carbon-carbon bonds) in component (A) and optional component (B), and preferably an amount of at least 0.3 moles, at least 0.4 moles, or at least 0.5 moles, or an amount of at most 2.5 moles, at most 2 moles, or at most 1.5 moles, and is an amount within any range between these upper and lower limits. This is because if the content of component (C) is equal to or greater than the lower limit of the above range, the resulting composition is sufficiently cured, while if it is equal to or less than the upper limit of the above range, the mechanical properties of the resulting cured product are improved.

[0043] Component (D) is a hydrosilylation catalyst that accelerates the curing of the composition, and examples of the catalyst include platinum catalysts, rhodium catalysts, and palladium catalysts, with platinum catalysts being preferred. Examples of platinum catalysts include platinum fine powder, platinum black, platinum-supported silica fine powder, platinum-supported activated carbon, chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum olefin complexes, and platinum alkenylsiloxane complexes.

[0044] The content of component (D) is an amount that promotes the curing of the composition, specifically, an amount in which the platinum atoms in the catalyst are within the range of 0.1 to 1,000 ppm by mass relative to the composition. This is because, if the content of component (D) is equal to or higher than the lower limit of the above range, the curing of the obtained composition proceeds sufficiently, whereas, if the content is equal to or lower than the upper limit of the above range, the obtained cured product is less likely to be colored.

[0045] The composition may contain a hydrosilylation reaction retarder to control the time until curing. Examples of the hydrosilylation reaction retarder include alkyne alcohols such as 1-ethynylcyclohexane-1-ol, 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, and 2-phenyl-3-butyn-2-ol; enyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane. Examples of the methyl alkenyl siloxane oligomer include alkyne oxysilanes such as dimethyl bis (3-methyl-1-butyne-3-oxy) silane and methyl vinyl bis (3-methyl-1-butyne-3-oxy) silane; alkyne oxysilane compounds such as methyl tris (1-methyl-1-phenyl propyne oxy) silane, dimethyl bis (1-methyl-1-phenyl propyne oxy) silane, methyl tris (1,1-dimethyl propyne oxy) silane and dimethyl bis (1,1-dimethyl propyne oxy) silane; and benzotriazole.

[0046] There are no limitations on the amount of this hydrosilylation reaction retarder, but in order to provide the composition with a sufficient pot life, it is preferable that the amount is within the range of 0.0001 to 5 parts by mass, 0.01 to 5 parts by mass, or 0.01 to 3 parts by mass, relative to 100 parts by mass of the total of components (A) to (D).

[0047] In addition, the composition may contain an organic compound having one aliphatic unsaturated bond and no siloxane bond in one molecule in order to reduce the crosslink density of the resulting cured product and thereby improve mechanical properties or adhesion. As such a compound, it is preferable that the compound has a boiling point of, for example, 200°C or higher under atmospheric pressure, since it shows good compatibility with the components (A) to (D) and has good storage stability. Specific examples of such a compound include linear aliphatic olefins such as dodecene, tetradecene, hexadecene, and octadecene; cyclic aliphatic olefins such as 4-phenyl-1-cyclohexene; and unsaturated alcohols such as 9-decen-1-ol, oleyl alcohol, and terpene-4-ol.

[0048] The content of these compounds is not limited, but in order to provide good curability of the composition and good mechanical properties of the resulting cured product, it is preferable that the content be within the range of 0 to 10 parts by mass, or within the range of 0 to 5 parts by mass, relative to 100 parts by mass of the total curable composition.

[0049] Furthermore, the present composition may contain a compound represented by the formula: R 9 SiO 3 / 2 and / or a siloxane unit represented by the formula: SiO2, and may contain a branched organopolysiloxane having a monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms. 7 is an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, a hydroxyl group, or an alkoxy group having 1 to 6 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group. Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, and a dodecenyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. In addition, the formula: R 9SiO 3 / 2 When the siloxane unit represented by the formula (I) does not have an alkenyl group, the other siloxane units include R 10 3SiO 1 / 2 Siloxane units represented by the formula: R 10 2SiO 2 / 2 In the formula, R 10 is an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, a hydroxyl group, or an alkoxy group having 1 to 6 carbon atoms, and examples thereof include the same groups as those described above. However, at least one R 10 is the alkenyl group.

[0050] The branched organopolysiloxane can be, for example, one or a mixture of two or more organopolysiloxanes represented by the following average unit formula: In the formula, Me, Vi, and Ph represent a methyl group, a vinyl group, and a phenyl group, respectively, and i, i', j, k, and l are numbers of 0 to 1 (but do not include 0) that represent the ratio of the constituent units, with the proviso that the sum of i, i', j, k, and l is 1. (Me3SiO 1 / 2 ) i (Me2ViSiO 1 / 2 ) i’ (PhSiO 3 / 2 ) k (Me3SiO 1 / 2 ) i (Me2ViSiO 1 / 2 ) i’ (PhSiO 3 / 2 ) k (SiO 4 / 2 ) l (Me3SiO 1 / 2 ) i (PhSiO 3 / 2 ) k (Me2ViSiO 1 / 2 ) i (PhSiO 3 / 2 ) k (Me2ViSiO 1 / 2 ) i (MeSiO2 / 2 ) j (PhSiO 3 / 2 ) k (Me2ViSiO 1 / 2 ) i (Me2SiO 2 / 2 ) j (PhSiO 3 / 2 ) k (SiO 4 / 2 ) l (Me2ViSiO 1 / 2 ) i (MePhSiO 2 / 2 ) j (MeSiO 3 / 2 ) k (Me2ViSiO 1 / 2 ) i (MePhSiO 2 / 2 ) j (PhSiO 3 / 2 ) k (Me3SiO 1 / 2 ) i (MeViSiO) 2 / 2 ) j (PhSiO 3 / 2 ) k (Me3SiO 1 / 2 ) i (MeViSiO) 2 / 2 ) j (PhSiO 3 / 2 ) k (SiO 4 / 2 ) l (Me3SiO 1 / 2 ) i (Me2SiO 2 / 2 ) j (PhSiO 3 / 2 ) k (Me3SiO 1 / 2 ) i (Me2SiO 2 / 2 ) j (PhSiO 3 / 2 ) k (SiO 4 / 2 ) l

[0051] The content of the branched organopolysiloxane is not limited, but is within the range of 0 to 20 parts by mass, preferably within the range of 0 to 10 parts by mass, or within the range of 0 to 5 parts by mass, relative to 100 parts by mass of the total of the curable composition. This is because if the content of the branched organopolysiloxane is equal to or greater than the upper limit of the above range, the viscosity of the obtained curable composition becomes high.

[0052] Other Additives In addition to the above components, further additives may be added to the composition of the present invention as desired. Examples of additives include, but are not limited to, the following:

[0053] [Adhesion imparting agent] An adhesion promoter can be added to the composition of the present invention in order to improve adhesion or adhesion to a substrate in contact with the composition. When the curable composition of the present invention is used for applications requiring adhesion or adhesion to a substrate, such as a coating agent or a sealing material, it is preferable to add an adhesion imparting agent to the curable composition of the present invention. As the adhesion promoter, any known adhesion promoter can be used as long as it does not inhibit the curing reaction of the composition of the present invention.

[0054] Examples of adhesion promoters that can be used in the present invention include organosilanes having a trialkoxysiloxy group (e.g., trimethoxysiloxy group, triethoxysiloxy group) or a trialkoxysilylalkyl group (e.g., trimethoxysilylethyl group, triethoxysilylethyl group) and a hydrosilyl group or an alkenyl group (e.g., vinyl group, allyl group), or organosiloxane oligomers having a linear, branched or cyclic structure with about 4 to 20 silicon atoms; organosilanes having a trialkoxysiloxy group or a trialkoxysilylalkyl group and a methacryloxyalkyl group (e.g., 3-methacryloxypropyl group); organosilanes, or organosiloxane oligomers having a linear, branched, or cyclic structure with about 4 to 20 silicon atoms; organosilanes having a trialkoxysiloxy group or a trialkoxysilylalkyl group and an epoxy group-bonded alkyl group (e.g., 3-glycidoxypropyl group, 4-glycidoxybutyl group, 2-(3,4-epoxycyclohexyl)ethyl group, 3-(3,4-epoxycyclohexyl)propyl group), or organosiloxane oligomers having a linear, branched, or cyclic structure with about 4 to 20 silicon atoms; organic compounds having two or more trialkoxysilyl groups (e.g., trimethoxysilyl group, triethoxysilyl group);Examples of the reaction product of aminoalkyltrialkoxysilane and epoxy group-bonded alkyltrialkoxysilane, and epoxy group-containing ethyl polysilicate include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hydrogentriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 1,6-bis(trimethoxysilane), silyl)hexane, 1,6-bis(triethoxysilyl)hexane, 1,3-bis[2-(trimethoxysilyl)ethyl]-1,1,3,3-tetramethyldisiloxane, reaction product of 3-glycidoxypropyltriethoxysilane and 3-aminopropyltriethoxysilane, condensation reaction product of silanol group-blocked methylvinylsiloxane oligomer and 3-glycidoxypropyltrimethoxysilane, condensation reaction product of silanol group-blocked methylvinylsiloxane oligomer and 3-methacryloxypropyltriethoxysilane, and tris(3-trimethoxysilylpropyl)isocyanurate.

[0055] The amount of adhesion promoter added to the curable composition of the present invention is not particularly limited, but in order not to promote the curing characteristics of the curable composition or discoloration of the cured product, it is preferably within the range of 0 to 5 parts by mass, or within the range of 0 to 2 parts by mass, relative to 100 parts by mass of the total of the components (A), (C), and (D).

[0056] Furthermore, the composition may contain a component that does not affect the properties of the composition even if it remains in the cured product, and that reduces the viscosity of the composition. There is no restriction on the structure, but in consideration of the miscibility with the components (A) to (C), a compound having at least one monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms in the molecule is preferred. Specifically, a diorganosiloxane oligomer having at least one monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms in the molecule is exemplified.

[0057] The monovalent functional group selected from the aromatic group having 6 to 12 carbon atoms and the aralkyl group having 7 to 12 carbon atoms includes those mentioned above, and is preferably a phenyl group or a phenethyl group. This compound does not have a hydrosilylation reactive functional group in the molecule. Examples of the hydrosilylation reactive functional group include an alkenyl group and a silicon atom-bonded hydrogen atom. Examples of the group bonded to the silicon atom other than the monovalent functional group in this compound include an alkyl group having 1 to 12 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, a undecyl group, and a dodecyl group; and a halogen-substituted alkyl group having 1 to 12 carbon atoms such as a 3-chloropropyl group and a 3,3,3-trifluoropropyl group. From the viewpoints of economy and heat resistance, a methyl group is preferred.

[0058] Specific molecular structures of such compounds include, for example, linear, partially branched linear, branched, cyclic, and three-dimensional network structures, and cyclic structures are preferred because they have good affinity with the cured product obtained by curing the composition and have a large viscosity reducing effect. Such compounds are represented by the general formula: [ka] In the formula, R is the same or different, and is a monovalent hydrocarbon group having 1 to 12 carbon atoms that does not have an aliphatic unsaturated bond, and examples thereof include the same alkyl group, aryl group, aralkyl group, and halogen-substituted alkyl group as described above. However, in one molecule, at least one R is a monovalent functional group selected from aromatic groups having a prime number of 6 to 12 and aralkyl groups having a carbon number of 7 to 12, and it is particularly preferable that 5 to 60 mol % of all R in one molecule are the above monovalent functional groups. In addition, in the formula, x is an integer of 3 to 10.

[0059] The viscosity of this compound at 25°C is not particularly limited, but is preferably within the range of 1 to 500 mPa·s, 1 to 300 mPa·s, or 1 to 100 mPa·s. This is because, when the viscosity of this compound is equal to or higher than the lower limit of the above range, the mechanical properties of the resulting cured product are not changed, whereas, when the viscosity is equal to or lower than the upper limit of the above range, the viscosity of the resulting composition can be sufficiently reduced.

[0060] The content of such a compound is within a range of 0 to 25 parts by mass relative to 100 parts by mass of the total of the curable composition, and preferably the upper limit is 20 parts by mass, 15 parts by mass, or 10 parts by mass.

[0061] [Other additives] In addition to the adhesion promoter described above, or instead of the adhesion promoter, other additives may be added to the composition of the present invention as desired. Examples of additives that can be used include leveling agents, silane coupling agents not included in the adhesion promoters described above, ultraviolet absorbers, antioxidants, polymerization inhibitors, fillers (functional fillers such as reinforcing fillers, insulating fillers, and thermally conductive fillers), and the like. If necessary, appropriate additives can be added to the composition of the present invention. In addition, if necessary, a thixotropic agent may be added to the composition of the present invention, especially when the composition is used as a potting agent or a sealing material.

[0062] The refractive index of the curable composition of the present invention is 1.47 or more as a value of the entire liquid composition before curing at 25°C and a wavelength of 847 nm. The refractive index value under these conditions is preferably 1.48 or more. Due to this characteristic, the refractive index of the cured product obtained by curing the composition is sufficiently high, and in various devices using an infrared LED as a light source, the interfacial reflection between the optical glass and other light transmitting layers can be reduced, and the light extraction efficiency can be increased.

[0063] The viscosity of the composition is 500 mPa·s or less as measured at 25°C using an E-type viscometer to enable application to injection molding. A preferred viscosity range is 5 to 200 mPa·s, more preferably 5 to 100 mPa·s, and even more preferably 10 to 100 mPa·s, under the above-mentioned measurement conditions. This is because, when the viscosity of the composition is at or above the lower limit of the above range, the mechanical properties of the resulting cured product are good, whereas, when the viscosity is at or below the upper limit of the above range, the resulting composition has good injection moldability and is less likely to entrap air in the cured product.

[0064] This composition can be prepared by uniformly mixing the components (A), (C), and (D), and, if necessary, any other optional components. When preparing this composition, the components can be mixed at room temperature using various stirrers or kneaders, and, if necessary, can be mixed under heating. There is also no limitation on the order in which the components are mixed, and they can be mixed in any order. The composition can be a one-liquid composition in which all components are mixed in the same container, or a two-liquid composition in which components are mixed at the time of use, taking storage stability into consideration. When a two-liquid composition is used, it is common for one composition to be a mixture of components (A), (B), (D), and other optional components, and for the other composition to be a mixture of components (A), (B), (C), and other optional components.

[0065] The composition can be cured at room temperature or at relatively low temperatures (for example, below 80° C.). The curing reaction of the composition can be adjusted to the desired speed by adjusting the concentration of the catalytic metal in component (D) and the type and amount of the hydrosilylation reaction retarder described above.

[0066] The cured product obtained by curing the composition has a high refractive index, and the refractive index of the cured product is preferably 1.50 or more at 25°C and a wavelength of 847 nm. The refractive index of the cured product under these conditions is preferably 1.52 or more, and more preferably 1.54 or more. Due to this characteristic, the refractive index of the cured product obtained by curing the composition is sufficiently high, and in various devices using infrared LEDs as a light source, it is possible to reduce interface reflection between optical glass and other light transmitting layers and increase light extraction efficiency.

[0067] This composition is useful as various injection agents, potting agents, sealants, and adhesives, and is particularly useful as an optical filler for forming light-transmitting layers for various devices using infrared LEDs, particularly display devices. The cured product is less colored and less likely to become cloudy under high temperature or high temperature and high humidity conditions, making it suitable as a light-transmitting layer for display devices using infrared LEDs.

[0068] This composition cures at a relatively low temperature, so it can be used to coat substrates with poor heat resistance. Such substrates are generally transparent substrates such as glass, synthetic resin films and sheets, and transparent electrode coatings. In addition, injection molding is an example of a coating method for this composition, taking advantage of its low viscosity characteristics.

[0069] Next, the cured product of the present invention will be described in detail. The cured product of the present invention is characterized by being obtained by curing the above-mentioned curable silicone composition. The shape of the cured product is not limited, and examples of the shape include a sheet, a film, a tape, and a block. It may also be integrated with various substrates.

[0070] The present cured product can be formed, for example, by applying the present composition to a film-like substrate, a tape-like substrate, or a sheet-like substrate, and then curing the composition at room temperature or by low-temperature heating to form a cured film made of the present cured product on the surface of the substrate. The present composition can also be injected between two substrates, and cured at room temperature or by heat treatment to form a cured product integrated with the substrate. The film thickness of the cured product is not limited, but is preferably 1 to 3000 μm, more preferably 10 to 2000 μm.

[0071] The display device of the present invention is produced using the curable liquid silicone composition of the present invention, and examples thereof include passive display devices such as LCDs (liquid crystal displays) and ECDs (electrochromic displays), and light-emitting display devices such as ELDs (electroluminescent displays). In the display device of the present invention, the space between the display unit such as a liquid crystal or organic EL display and a display-forming member such as a touch panel or cover lens, or between the display-forming members, is filled with a cured product of the curable liquid silicone composition of the present invention, thereby reducing interfacial reflection and increasing light extraction efficiency.

[0072] A typical method for manufacturing the display device of the present invention is the injection molding method, taking advantage of the low viscosity characteristic of the curable liquid silicone composition of the present invention. Specifically, the composition is injected into a narrow gap between an infrared LED light source substrate and various transparent substrates, and cured by heating to manufacture a display device.

[0073] The present invention will be further described below based on examples, but the present invention is not limited to the following examples. EXAMPLES

[0074] The curable liquid silicone composition of the present invention and its cured product will be described in detail with reference to the following examples. In the formulas, Me, Vi, and Ph represent methyl, vinyl, and phenyl groups, respectively. Measurements and evaluations in the examples were performed as follows.

[0075] [Viscosity of the Curable Liquid Silicone Composition and Each Component] The viscosity (mPa·s) at 25°C of the curable liquid silicone composition and each of its components was measured using a VISCONIC EMD E-type viscometer manufactured by Tokimec Inc.

[0076] [Chemical structure of organopolysiloxane] The chemical structure of the organopolysiloxane was identified by nuclear magnetic resonance spectroscopy.

[0077] [Appearance of the curable liquid silicone composition] The appearance of the curable liquid silicone composition was visually observed and rated as follows. A:Transparent B: Slightly cloudy

[0078] [Transparency and haze of the cured product] The curable liquid silicone composition was filled between two glass plates (filling area: 40 × 40 mm) so that the thickness after curing was 200 microns. 2 ) and heated in an oven at 90° C. for 1 hour. The total light transmittance and haze of the cured sheet formed between two glass plates were measured using an SH7000 haze meter manufactured by Nippon Denshoku Industries Co., Ltd. according to the method specified in JIS K7361-1.

[0079] [Hardness of cured product] The curable liquid silicone composition was placed in a glass cup with a diameter of 25 mm and a depth of 10 mm, and heated in an oven at 90°C for 1 hour. The penetration of the resulting cured product at room temperature was measured using a penetration tester in accordance with JIS K2207. For products with high hardness, the penetration was measured using a type A durometer in accordance with ASTM D 2240.

[0080] [Refractive index of cured product] The refractive index at a wavelength of 847 nm of the cured product prepared for the hardness measurement described above was measured at 25° C. using a Metricon Model 2010 / M prism coupler.

[0081] [Examples 1 to 9, Comparative Example 1] A solventless curable liquid silicone composition was prepared using the following components. Components (A) to (E) were mixed at room temperature using a planetary centrifugal mixer to prepare a curable composition. The mixing ratios (parts by mass) of the components, the physical properties of the curable composition, and the characteristics of the cured product are summarized in Table 1.

[0082] The following compound was used as component (A). (A1) 1,5-divinyl-3,3-diphenyl-1,1,5,5-tetramethyltrisiloxane (A2) Phenyl-tris(dimethylvinylsiloxy)silane (A3) 1,3-di(5-hexenyl)-1,1,3,3-tetramethyldisiloxane

[0083] The following organopolysiloxane was used as component (B). A polymethylphenylsiloxane with a viscosity of 3,000 mPa s at 25°C and both ends of the molecular chain capped with dimethylvinylsiloxy groups, represented by the following formula: Me2ViSiO(MePhSiO) 25 SiMe2Vi

[0084] The following components were used as component (C): (C1): 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane (C2): Average unit formula: (Me2HSiO 1 / 2 ) 0.6 (PhSiO 3 / 2 ) 0.4 Organopolysiloxane with a viscosity of 20 mPa·s.

[0085] The following components were used as component (D): A phenyl-tris(dimethylvinylsiloxy)silane solution of platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex having a platinum content of 0.45% by mass.

[0086] The following components were used as component (E): 1% by weight solution of 1-ethynylcyclohexan-1-ol in 1,5-divinyl-1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane

[0087] [Table 1] *The number of moles of the total silicon-bonded hydrogen atoms in components (C1) and (C2) per mole of the total vinyl groups in components (A1), (A2), (A3), and (B).

[0088] From the results of Examples 1 to 9, the curable liquid silicone composition of the present invention has a very low viscosity and good transparency. It was also confirmed that the transparency of the cured product obtained by curing is high, and the refractive index, particularly in the infrared region, is high. It was also demonstrated that the hardness of the cured product can be adjusted over a wide range by appropriately changing the components used and their contents. On the other hand, from the results of Comparative Example 1, it was confirmed that the viscosity of the curable liquid silicone composition not containing component (A) is very high. [Industrial Applicability]

[0089] The curable liquid silicone composition of the present invention has a very low viscosity at room temperature, making it suitable for injection molding. It also cures quickly by heat treatment, which contributes to improving productivity. Furthermore, the resulting cured product has excellent transparency and a high refractive index, especially in the infrared region (1.50 or higher), making it useful as a material for devices using infrared LED light sources.

Claims

1. (A) One or more organosilicon compounds selected from the following components (A1) and (A2): (A1) an organosilane or organopolysiloxane having 1 to 5 silicon atoms, at least two alkenyl groups having 2 to 12 carbon atoms in one molecule, and at least one monovalent functional group selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms; (A2) a linear or branched organopolysiloxane having 2 to 5 silicon atoms, at least two alkenyl groups having 2 to 12 carbon atoms in one molecule, and no monovalent functional group selected from aromatic groups having 6 to 12 carbon atoms and aralkyl groups having 7 to 12 carbon atoms, and having a boiling point of 180°C or higher under normal pressure; (B) The following formula (1): 【Chemistry 1】 （１） (In the formula, R 1 is an alkenyl group having 2 to 12 carbon atoms; R 2 and R 3 are each independently an unsubstituted or fluorine-substituted monovalent alkyl group having 1 to 10 carbon atoms; R 4 is each independently a monovalent functional group selected from an unsubstituted or fluorine-substituted aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms; R 5 and R 6 are each independently a monovalent functional group selected from an unsubstituted or fluorine-substituted monovalent alkyl group having 1 to 10 carbon atoms, an aromatic group having 6 to 12 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms; m and n are numbers that satisfy the relationships 0≦m<1,000, 0≦n<500, and 3≦m+n<1,500; and 34 mol % or more of all R 1 to R 6 are monovalent functional groups selected from an aromatic group having 6 to 12 carbon atoms and an aralkyl group having 7 to 12 carbon atoms). A linear polysiloxane having an alkenyl group at the molecular chain terminal, represented by the formula: (C) a compound having at least two silicon-bonded hydrogen atoms in one molecule (an amount such that the number of silicon-bonded hydrogen atoms in this component is 0.2 to 3 moles per mole of the total number of alkenyl groups in the composition), and (D) Hydrosilylation reaction catalyst wherein when the total amount of components (A), (C), (D) and (B) is taken as 100 parts by mass, the amount of component (B) is in the range of 1 to 90 parts by mass, the refractive index of the entire liquid composition before curing is 1.47 or greater at 25°C and a wavelength of 847 nm, and the viscosity of the entire liquid composition measured at 25°C using an E-type viscometer is in the range of 5 to 200 mPa s.

2. 2. The curable liquid silicone composition according to claim 1, wherein component (A) is a linear or branched organopolysiloxane having 2 to 5 silicon atoms.

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

4. The cured product according to claim 3, which has a refractive index of 1.50 or more at 25°C and a wavelength of 847 nm.

5. An optical filler comprising the curable liquid silicone composition of claim 1 or claim 2.

6. A display device comprising a layer made of a cured product of the curable liquid silicone composition according to claim 1 or 2.

7. 3. A method for producing a display device, comprising the steps of: injecting the curable liquid silicone composition according to claim 1 or 2 between a light source substrate and a transparent substrate; and curing the injected curable liquid silicone composition by heating.

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