Polysiloxane composition and use thereof

Abstract

Provided is a composition with which a coating film having a low refractive index can be formed and that has excellent storage stability and coatability. The composition contains 10-90 parts by mass of a branched polysiloxane represented by formula (1) and having a refractive index of less than 1.45 at a wavelength of 633 nm, and 90-10 parts by mass of an organic solvent other than benzene, toluene, ethylbenzene, and xylene. (1): RA aRb(OZ)cSiO(4-a-b-c) / 2 RA is a C3-12 monovalent aliphatic saturated hydrocarbon group, R is a hydrogen atom, a methyl group, an ethyl group, a C2-12 monovalent aliphatic unsaturated hydrocarbon group, or a C6-12 monovalent aromatic hydrocarbon group, and Z is a hydrogen atom or a C1-4 monovalent aliphatic saturated hydrocarbon group. In addition, a, b, and c satisfy 0.2 ≤ a < 1; 0 < b ≤ 1.5; 0 < c < 0.8; 0.5 < a + b ≤ 1.8; and 0 < b × c ≤ 0.4.

Description

Polysiloxane composition and its uses

[0001] The present invention relates to a polysiloxane composition and its use.

[0002] Polysiloxanes have high heat resistance and excellent chemical stability, and are therefore used as coating agents, potting agents, insulating materials, and the like for electronic and electrical devices.

[0003] Low-refractive index materials are used in various display devices, such as those for mobile devices, industrial equipment, and car navigation systems, for purposes such as anti-reflection and protection of various functional components. Fluorinated polymer materials are well-known as representative low-refractive index materials. However, recent research has revealed that fluorinated polymer materials are persistently biodegradable, highly bioaccumulative, and have concerns about their safety for living organisms. Therefore, there is a global movement to restrict fluorinated polymer materials. Polysiloxane-containing coating materials are attracting attention as alternative materials.

[0004] Here, since polysiloxanes are generally easily soluble in TX solvents such as toluene and xylene, polysiloxane compositions containing polysiloxane and TX solvents are sometimes used as coating materials. On the other hand, from the viewpoint of reducing the burden on the environment, techniques have been proposed for preparing polysiloxane compositions using organic solvents other than TX solvents (see, for example, Patent Documents 1 to 3).

[0005] JP 2021-172706 A JP 2021-172707 A International Publication No. 2020 / 036074

[0006] However, although the above-mentioned conventional polysiloxane compositions are capable of forming coating films that require a low refractive index, they have problems such as excessive viscosity increase when stored for a long period of time and uneven coating when applied to a substrate such as a silicon wafer. In other words, the above-mentioned conventional polysiloxane compositions have room for improvement in terms of forming coating films with a low refractive index while exhibiting excellent storage stability and coatability to substrates.

[0007] Therefore, an object of the present invention is to provide a polysiloxane composition that is capable of forming a coating film with a low refractive index and that has excellent storage stability and applicability to substrates, and uses thereof.

[0008] The present inventors have conducted extensive research to achieve the above object, and have newly discovered that a polysiloxane composition containing a branched polysiloxane having a specified composition and properties and a specified organic solvent has excellent storage stability and coatability onto a substrate, and further, that the polysiloxane composition can be used to form a coating film with a low refractive index, thereby completing the present invention.

[0009] That is, according to the present invention, there are provided polysiloxane compositions [1] to [9], an insulating coating agent

[10] , an insulating coating

[11] , a method for producing an insulating coating

[12] , and a display device

[13] , all of which are described below.

[0010] [1] (A) The following average composition formula (1): R Ａ ａ R ｂ (OZ) ｃ SiO （４－ａ－ｂ－ｃ）／２ (1) (In formula (1), R Ａ a<b<c<0.8; 0.5<a+b<1.8; 0<b×c<0.4. 1. A polysiloxane composition comprising: (a) a branched polysiloxane having a refractive index of less than 1.45 at a wavelength of 633 nm; and (b) an organic solvent other than benzene, toluene, ethylbenzene, or xylene; (b) an organic solvent other than benzene, toluene, ethylbenzene, or xylene; and (c) an organic solvent other than benzene, toluene, ethylbenzene, or xylene; and (d) a branched polysiloxane having a refractive index of less than 1.45 at a wavelength of 633 nm; and (e) an organic solvent other than benzene, toluene, ethylbenzene, or xylene; and (f) an organic solvent other than benzene, toluene, ethylbenzene, or xylene; and (g) a branched polysiloxane having a refractive index of less than 1.45 at a wavelength of 633 nm; and (g) an organic solvent other than benzene, toluene, ethylbenzene, or xylene; and (h) a branched polysiloxane having a refractive index of less than 1.45 at a wavelength of 633 nm; and (g) an organic solvent other than benzene, toluene, ethylbenzene, or xylene ...

[0011] [2] The polysiloxane composition according to [1] above, wherein Z in the average composition formula (1) contains a hydrogen atom.

[0012] [3] R in the average composition formula (1)Ａ The polysiloxane composition according to the above [1] or [2], wherein contains an n-propyl group.

[0013] [4] The polysiloxane composition according to any one of [1] to [3] above, wherein R in the average composition formula (1) contains a methyl group and does not contain a monovalent aromatic hydrocarbon group having from 6 to 12 carbon atoms.

[0014] [5] The polysiloxane composition according to the above [1], wherein the component (A) is a branched polysiloxane represented by the following average unit formula (2): (R ３ SiO １／２ ) ｋ１ (R Ａ R ２ SiO １／２ ) ｋ２ (R ２ SiO ２／２ ) L１ (R Ａ RSiO ２／２ ) L２ (RSiO ３／２ ) ｍ１ (R Ａ SiO ３／２ ) ｍ２ (SiO ４／２ ) ｎ (ZO １／２ ) ｚ (2) (In formula (2), R Ａ , R, and Z have the same meanings as above, 0≦k1+k2≦0.5, 0≦L1+L2≦0.5, 0<m1+m2≦1, 0≦n≦0.6, 0<z<0.8, k1+k2+L1+L2+m1+m2+n=1, and 0<(3×k1+2×k2+2×L1+L2+m1)×z≦0.4.

[0015] [6] The polysiloxane composition according to [5] above, wherein k2, L1, L2, and n in the average unit formula (2) are all 0, and 0<m2.

[0016] [7] The polysiloxane composition according to any one of [1] to [6] above, wherein component (B) comprises at least one selected from the group consisting of propylene glycol alkyl ether compounds and alkylcycloalkane compounds.

[0017] [8] The polysiloxane composition according to any one of [1] to [6] above, wherein the component (B) comprises at least one selected from propylene glycol methyl ether, propylene glycol methyl ether acetate, methylcyclohexane, and ethylcyclohexane.

[0018] [9] The polysiloxane composition according to any one of [1] to [6] above, wherein component (B) contains methylcyclohexane.

[0019]

[10] An insulating coating agent comprising the polysiloxane composition according to any one of [1] to [9] above.

[0020]

[11] An insulating coating formed using the polysiloxane composition according to any one of [1] to [9] above.

[0021]

[12] A method for producing an insulating coating, comprising a step of removing the component (B) from the polysiloxane composition according to any one of [1] to [9] above.

[0022]

[13] A display device comprising a layer made of a solid material formed using the polysiloxane composition according to any one of [1] to [9] above. The display device may be, for example, a liquid crystal display, an organic electroluminescence display, or an organic electroluminescence flexible display.

[0023] According to the present invention, it is possible to provide a polysiloxane composition that is capable of forming a coating film with a low refractive index and that has excellent storage stability and applicability to substrates, and uses thereof.

[0024] Hereinafter, embodiments of the present invention will be described in detail. The upper and lower limit values ​​of the numerical ranges described in this specification can be arbitrarily combined. For example, when a numerical range is described as "preferably 30 to 100, more preferably 40 to 80," the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described in this specification. Furthermore, when a numerical range is described as "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less," the ranges "30 to 80" and "40 to 100" are also included in the numerical ranges described in this specification. Additionally, when a numerical range described in this specification, for example, "60 to 100," means a range of "60 or more and 100 or less."

[0025] (Polysiloxane Composition) The polysiloxane composition of the present invention comprises, as essential components, a branched polysiloxane, which is component (A), and an organic solvent, which is component (B). The amount of component (A) contained in the polysiloxane composition of the present invention is 10 to 90 parts by mass, where the total mass of components (A) and (B) is 100 parts by mass. In addition, the amount of component (B) contained in the polysiloxane composition of the present invention is 10 to 90 parts by mass, where the total mass of components (A) and (B) is 100 parts by mass. The polysiloxane composition of the present invention may optionally contain other components in addition to components (A) and (B).

[0026] <Component (A): Branched Polysiloxane> Component (A) of the present invention is represented by the following average composition formula (1): R Ａ ａ R ｂ (OZ) ｃ SiO （４－ａ－ｂ－ｃ）／２ (1)

[0027] In the above formula (1), R Ａis a monovalent aliphatic saturated hydrocarbon group having 3 to 12 carbon atoms, R is a hydrogen atom, a methyl group, an ethyl group, a monovalent aliphatic unsaturated hydrocarbon group having 2 to 12 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, Z is a hydrogen atom or a monovalent aliphatic saturated hydrocarbon group having 1 to 4 carbon atoms, and a, b, and c are numbers that satisfy the following conditions: 0.2≦a<1; 0<b≦1.5; 0<c<0.8; 0.5<a+b≦1.8; 0<b×c≦0.4. In this specification, the composition of the branched polysiloxane is １３ C-NMR spectroscopy and ２９ The identification can be performed by nuclear magnetic resonance spectroscopy such as Si-NMR spectroscopy.

[0028] In the above formula (1), R Ａ As described above, R is a monovalent aliphatic saturated hydrocarbon group having 3 to 12 carbon atoms. Ａ The monovalent aliphatic saturated hydrocarbon group having 3 to 12 carbon atoms constituting R is not particularly limited, but examples thereof include linear or branched aliphatic saturated hydrocarbon groups such as n-propyl group, isopropyl group, n-butyl group, tert-butyl group, sec-butyl group, pentyl group, hexyl group, octyl group, and decyl group; and cyclic aliphatic saturated hydrocarbon groups such as cyclopentyl group and cyclohexyl group. Ａ may be one type or two or more types. That is, the branched polysiloxane of component (A) is Ａ The alkyl group may contain only one type of monovalent aliphatic saturated hydrocarbon group having 3 to 12 carbon atoms, or may contain two or more types of monovalent aliphatic saturated hydrocarbon groups having 3 to 12 carbon atoms.

[0029] In one embodiment of the present invention, R Ａ In consideration of the refractive index of component (A), preferably contains a linear aliphatic saturated hydrocarbon group, and more preferably contains an n-propyl group.

[0030] In the above formula (1), as described above, R is a hydrogen atom, a methyl group, an ethyl group, a monovalent aliphatic unsaturated hydrocarbon group having from 2 to 12 carbon atoms, or a monovalent aromatic hydrocarbon group having from 6 to 12 carbon atoms. The monovalent aliphatic unsaturated hydrocarbon group having from 2 to 12 carbon atoms that constitutes R is not particularly limited, but examples thereof include alkenyl groups such as a vinyl group, an allyl group, a butenyl group, and a hexenyl group. The monovalent aromatic hydrocarbon group having from 6 to 12 carbon atoms that constitutes R is not particularly limited, but examples thereof include aryl groups such as a phenyl group and a naphthyl group; and arylalkyl groups such as a benzyl group and a phenylethyl group.

[0031] In one embodiment of the present invention, in consideration of the refractive index of component (A), R in the above formula (1) preferably contains at least one of a methyl group and a vinyl group, and more preferably contains a methyl group. In one embodiment of the present invention, in consideration of the refractive index of component (A), R in the above formula (1) preferably does not contain a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms. In one embodiment of the present invention, in consideration of the refractive index of component (A), R in the above formula (1) preferably all contain at least one of a methyl group and a vinyl group, and more preferably all contain methyl groups.

[0032] In the above formula (1), Z is, as described above, a hydrogen atom or a monovalent aliphatic saturated hydrocarbon group having 1 to 4 carbon atoms.

[0033] In one embodiment of the present invention, Z in the above formula (1) preferably contains at least one selected from the group consisting of a hydrogen atom, a methyl group, and an ethyl group, more preferably contains at least one of a hydrogen atom and a methyl group, and even more preferably contains a hydrogen atom. When Z in the above formula (1) is a hydrogen atom, the coatability of the polysiloxane composition to a substrate is further improved.

[0034] In the above formula (1), the substituent R ＡThe ratio a satisfies 0.2≦a<1 (in other words, 0.2 or more and less than 1). When the ratio a is 0.2 or more and less than 1, the storage stability of the polysiloxane composition can be ensured. In one aspect of the present invention, from the viewpoint of further improving the storage stability of the polysiloxane composition, the ratio a is preferably 0.3 or more, and more preferably 0.4 or more. In another aspect of the present invention, the ratio a can be 0.9 or less, 0.8 or less, 0.7 or less, or 0.6 or less.

[0035] In the above formula (1), b, which represents the ratio of the substituents R, satisfies 0<b≦1.5 (in other words, more than 0 and less than or equal to 1.5). When the ratio b is more than 0 and less than or equal to 1.5, the refractive index of component (A) can be reduced. In one aspect of the present invention, from the viewpoint of further reducing the refractive index of component (A), the ratio b is preferably 0.3 or more, and more preferably 0.4 or more. In one aspect of the present invention, the ratio b can be 1.2 or less, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, or 0.6 or less.

[0036] In the above formula (1), c, which represents the ratio of the remaining reactive groups OZ, satisfies 0<c<0.8 (in other words, more than 0 and less than 0.8). When the ratio c is greater than 0, the coatability to a substrate can be improved, and when it is less than 0.8, the storage stability and coatability to a substrate of the polysiloxane composition can be improved. In one aspect of the present invention, the ratio c is preferably 0.03 or more and preferably 0.6 or less. Furthermore, in one aspect of the present invention, from the viewpoint of further improving the storage stability and coatability to a substrate of the polysiloxane composition, the content of silanol groups (Si—OH) per mole of silicon atoms in the branched polysiloxane of component (A) is preferably more than 0 moles, more preferably 0.03 moles or more, and preferably 0.6 moles or less.

[0037] In the above formula (1), the interrelationship between the ratios a, b, and c is defined by the following two relational expressions (3) and (4): 0.5<a+b≦1.8 (3) 0<b×c≦0.4 (4)

[0038] In the above relational formula (3), the ratio of the substituent R Ａ The substituents R, whose ratio is represented by a and b, can both affect the strength of the coating film (coating film strength) formed using the polysiloxane composition. When the sum of a and b is greater than 0.5, the coating film is prevented from becoming brittle, and when it is 1.8 or less, the hardness of the coating film can be ensured. That is, when a + b satisfies the above relational formula (3), the coating film formed using the polysiloxane composition achieves good strength, making it particularly suitable for coating applications. In one embodiment of the present invention, a + b is preferably 0.7 or more, more preferably 0.8 or more, and preferably 1.5 or less, more preferably 1.2 or less.

[0039] In the above relational expression (4), the substituent R, whose ratio is represented by b, can affect the refractive index of component (A), and the reactive group OZ, whose ratio is represented by c, can affect the storage stability of the polysiloxane composition and its coatability to substrates. Furthermore, by making the product of b and c greater than 0 and equal to or less than 0.4, the refractive index of component (A) can be reduced while ensuring the storage stability of the polysiloxane composition and its coatability to substrates. That is, in component (A) contained in the polysiloxane composition of the present invention, when the ratio b of the low-refractive-index-contributing component R is high, it is effective to reduce the ratio c of the residual reactive group OZ, and the reverse combination is also possible. In one embodiment of the present invention, b × c is preferably 0.02 or more and 0.3 or less.

[0040] In one embodiment of the present invention, the component (A) represented by the above-mentioned average composition formula (1) may be a branched polysiloxane represented by the following average unit formula (2): (R ３ SiO １／２ ) ｋ１ (R Ａ R ２ SiO １／２ ) ｋ２ (R ２ SiO ２／２ ) L１ (R ＡRSiO ２／２ ) L２ (RSiO ３／２ ) ｍ１ (R Ａ SiO ３／２ ) ｍ２ (SiO ４／２ ) ｎ (ZO １／２ ) ｚ (2)

[0041] In the above formula (2), R Ａ , R, and Z have the same meanings as in the above formula (1), and the preferred examples thereof are also the same. In the above formula (2), as in the above formula (1), the substituent R Ａ contributes primarily to the storage stability of the polysiloxane composition, and the substituent R contributes primarily to lowering the refractive index of component (A). The reactive group OZ having Z as a part thereof can primarily affect the storage stability and coatability of the polysiloxane composition to a substrate.

[0042] In the above formula (2), the trifunctional siloxane unit "R ３ SiO １／２ " ratio k1 and "R Ａ R ２ SiO １／２ The ratio k2 of " satisfies 0≦k1+k2≦0.5 (in other words, 0 or more and 0.5 or less). That is, the trifunctional siloxane unit does not need to be contained in the branched polysiloxane represented by formula (2). In one aspect of the present invention, k1+k2 is preferably 0.3 or less, and more preferably 0.2 or less. When k1+k2 is 0.5 or less, it is possible to suppress a decrease in the softening point and strength (coating strength) of a coating film formed using the polysiloxane composition. As described above, in one aspect of the present invention, the branched polysiloxane represented by formula (2) does not need to contain a trifunctional siloxane unit. On the other hand, when the branched polysiloxane contains a trifunctional siloxane unit, there is an advantage in that it becomes easier to control the molecular weight of the branched polysiloxane.

[0043] In the above formula (2), the bifunctional siloxane unit "R ２ SiO ２／２ " ratio L1 and "RＡ RSiO ２／２ The ratio L2 of " satisfies 0≦L1+L2≦0.5 (in other words, 0 or more and 0.5 or less). That is, like the trifunctional siloxane unit, the difunctional siloxane unit does not need to be included in the branched polysiloxane represented by formula (2). In one aspect of the present invention, L1+L2 is preferably 0.3 or less, more preferably 0 or more and 0.2 or less, and even more preferably 0. When L1+L2 is 0.5 or less, a decrease in the softening point and strength (coating strength) of a coating film formed using the polysiloxane composition can be suppressed. As described above, in one aspect of the present invention, the branched polysiloxane does not need to contain a difunctional siloxane unit. On the other hand, when the branched polysiloxane contains a difunctional siloxane unit, there is an advantage in that flexibility can be imparted to a coating film formed using the polysiloxane composition.

[0044] In the above formula (2), the monofunctional siloxane unit "RSiO ３／２ " ratio m1 and "R Ａ SiO ３／２ " satisfies 0 < m1 + m2 ≦ 1 (in other words, greater than 0 and equal to or less than 1). That is, the monofunctional siloxane unit is contained in the branched polysiloxane represented by formula (2). In one aspect of the present invention, m1 + m2 is preferably 0.4 or greater, more preferably 0.5 or greater, even more preferably 0.6 or greater, and particularly preferably 0.7 or greater. When the ratio c is 0.4 or greater, the softening point of the coating film formed using the polysiloxane composition can be increased. In one aspect of the present invention, the ratio m1 + m2 can be 0.95 or less, or 0.92 or less.

[0045] In the above formula (2), the non-functional siloxane unit "SiO ４／２" satisfies 0≦n≦0.6 (in other words, 0 or more and 0.6 or less). That is, like the trifunctional siloxane unit and the difunctional siloxane unit, the nonfunctional siloxane unit does not have to be contained in the branched polysiloxane. In one aspect of the present invention, the ratio n is preferably 0.4 or less, more preferably 0.2 or less, even more preferably 0.1 or less, and particularly preferably 0 (in other words, the branched polysiloxane does not contain nonfunctional siloxane units). When the ratio n is 0.6 or less, the brittleness of the coating film formed using the polysiloxane composition can be reduced. As described above, in one aspect of the present invention, the branched polysiloxane does not have to contain nonfunctional siloxane units. On the other hand, when the branched polysiloxane contains nonfunctional siloxane units, there is an advantage in that the softening point of the coating film formed using the polysiloxane composition can be increased.

[0046] In the above formula (2), the sum of the ratios k1, k2, L1, L2, m1, m2, and n satisfies k1+k2+L1+L2+m1+m2+n=1.

[0047] In the above formula (2), the remaining reactive group "ZO １／２ The ratio z in " satisfies the relationship 0<z<0.8 (in other words, greater than 0 and less than 0.8). When the ratio z is greater than 0, the coatability to a substrate can be improved, and when it is less than 0.8, the storage stability of the polysiloxane composition and the coatability to a substrate can be improved. In one aspect of the present invention, the ratio z is preferably 0.03 or more and 0.6 or less.

[0048] In the above formula (2), it is preferable that the interrelationship between the ratios k1, k2, L1, L2, m1, and z satisfy the following relational expression (5): 0<(3×k1+2×k2+2×L1+L2+m1)×z≦0.4 (5) When k1, k2, L1, L2, m1, and z satisfy the above relational expression (5), the storage stability and coatability of the polysiloxane composition to a substrate can be further improved. In the above relational expression (5), the substituent R, whose ratio is represented by (3×k1+2×k2+2×L1+L2+m1), can affect the refractive index of component (A), and the reactive group OZ, whose ratio is represented by z, can affect the storage stability and coatability of the polysiloxane composition to a substrate. Furthermore, by having the product of (3×k1+2×k2+2×L1+L2+m1) and z be greater than 0 and equal to or less than 0.4, the storage stability of the polysiloxane composition and its coatability onto substrates can be ensured while reducing the refractive index of component (A). In one embodiment of the present invention, (3×k1+2×k2+2×L1+L2+m1)×z is preferably equal to or greater than 0.02 and equal to or less than 0.3.

[0049] <<Properties>> The branched polysiloxane of component (A) has a refractive index of less than 1.45 at a wavelength of 633 nm. The refractive index is more preferably 1.44 or less. This characteristic allows the solid material obtained from the polysiloxane composition of the present invention to be widely used in various applications requiring low refractive index materials. The refractive index of component (A) is determined by the ratio of the substituent R on the silicon atom in the branched polysiloxane described above. Ａ The ratio of the substituents R, R, and OZ can be controlled. Ａ The refractive index of component (A) can be lowered by lowering the ratio of and increasing the ratio of the substituent R. In this specification, the "refractive index at a wavelength of 633 nm" of the branched polysiloxane that is component (A) refers to the refractive index at a wavelength of 633 nm measured in the state of a coating film prepared by the method described in the Examples below.

[0050] The weight-average molecular weight of the branched polysiloxane, component (A), is not particularly limited. In one embodiment of the present invention, the weight-average molecular weight of component (A) is preferably 1,000 or more, more preferably 1,500 or more, and preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 20,000 or less. If the weight-average molecular weight of component (A) is within the above-mentioned range, the coatability of the polysiloxane composition to a substrate can be further improved. In this specification, the "weight-average molecular weight" and the "number-average molecular weight" described below each refer to the molecular weight measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0051] The polydispersity index (hereinafter sometimes referred to as "PDI") of the branched polysiloxane, component (A), is not particularly limited. In one embodiment of the present invention, the polydispersity index of component (A) may be, for example, 1.5 or more and 20 or less. The higher the weight average molecular weight described above, the larger the PDI value tends to be. Note that PDI is defined as the value of "Mw / Mn" using the number average molecular weight (Mn) and the weight average molecular weight (Mw).

[0052] There are no particular restrictions on the softening point and glass transition temperature of the branched polysiloxane of component (A). In one embodiment of the present invention, the glass transition temperature of component (A) is preferably 30°C or higher. If the glass transition temperature of component (A) is 30°C or higher, the tackiness (adhesiveness) of the coating film surface can be reduced when the polysiloxane composition is applied to a substrate to form a coating film. In addition to reducing tackiness, taking into consideration the usage environment of electronic and electrical devices, particularly display devices, in which a coating film of the polysiloxane composition is used, the glass transition temperature is more preferably 60°C or higher, and even more preferably 100°C or higher. In this specification, the "glass transition temperature" of component (A) can be determined by a measurement method using a differential scanning calorimeter.

[0053] <<Method for Preparing Component (A)>> There are no particular limitations on the method for preparing the branched polysiloxane serving as component (A). Component (A) can be prepared using, for example, the following methods 1), 2), or 3). 1) A method in which a mixture containing starting materials including a plurality of alkoxysilanes and / or linear siloxanes, a reaction solvent, and an acidic catalyst is heated to carry out a hydrolysis and condensation reaction, thereby preparing a branched polysiloxane solution. 2) A method in which a mixture containing the same starting materials, reaction solvent, and basic catalyst as in method 1) is heated to carry out a hydrolysis and condensation reaction, thereby preparing a branched polysiloxane solution. 3) A method in which a mixture containing the same starting materials, reaction solvent, and acidic catalyst as in method 1) is heated to carry out a hydrolysis and condensation reaction, and then a basic catalyst is added to the resulting reaction solution to further react, thereby preparing a branched polysiloxane. In the above methods 1) to 3), operations such as removal of by-product alcohol and excess water, neutralization, and / or filtration may be performed at any time, as needed.

[0054] Among the above-mentioned methods 1) to 3), methods 1) and 3) are preferably applicable. Furthermore, since heavy metals such as platinum atoms are not contained in the products obtained by any of the above-mentioned methods 1) to 3), these methods are advantageous when applied to electronic materials, particularly electronic materials in the semiconductor field.

[0055] The above-mentioned method 3) will be further explained with a specific example. First, the starting materials, methyltrimethoxysilane, n-propyltrimethoxysilane, and hexamethyldisiloxane, are dissolved in methylcyclohexane as a reaction solvent, and aqueous hydrochloric acid is added as an acidic catalyst to obtain a mixture. This mixture is heated to carry out a hydrolysis and condensation reaction, yielding a reaction solution containing a reactive branched polysiloxane with a low degree of condensation. A basic catalyst, aqueous potassium hydroxide, is added to this reaction solution to make the reaction system basic. After that, the by-product methyl alcohol and excess water are removed, and the reaction mixture undergoes further neutralization and filtration steps to obtain a highly condensed poly(trimethylsiloxane / methylsiloxane / n-propylsiloxane) copolymer as component (A). The structure and molecular weight of the resulting component (A) can be controlled by the ratio of alkoxysilanes and / or linear siloxanes during the reaction, the type and amount of reaction solvent, the amount of water used, and the amount of basic catalyst.

[0056] <<Content of Component (A)>> As described above, the amount of component (A) contained in the polysiloxane composition of the present invention must be 10 parts by mass or more and 90 parts by mass or less, where the total mass of component (A) and component (B) is 100 parts by mass. When the amount of component (A) per 100 parts by mass of the total of component (A) and component (B) is within the above-mentioned range, the storage stability and coatability of the polysiloxane composition to a substrate can be ensured. Furthermore, it becomes easier to control the film thickness of a coating film formed from the polysiloxane composition. In one aspect of the present invention, from the viewpoint of further improving the storage stability and coatability of the polysiloxane composition to a substrate, the amount of component (A) contained in the polysiloxane composition of the present invention is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and preferably 80 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less, where the total mass of component (A) and component (B) is 100 parts by mass.

[0057] In one embodiment of the present invention, from the viewpoint of further improving the storage stability and coatability of the polysiloxane composition to a substrate, the amount of component (A) contained in the polysiloxane composition of the present invention is preferably 20% by mass or more, more preferably 30% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, and particularly preferably 50% by mass or less, based on the total mass of the polysiloxane composition being 100% by mass.

[0058] <Component (B): Organic Solvent Other Than Benzene, Toluene, Ethylbenzene, and Xylene> Component (B) of the present invention is an organic solvent other than benzene, toluene, ethylbenzene, and xylene. Component (B) has the function of controlling the coatability of component (A) and adjusting the thickness of the coating film. Furthermore, component (B) has the advantage of posing less concern for biological safety compared to benzene, toluene, ethylbenzene, and xylene.

[0059] <<Types of Component (B)>> Specific examples of usable organic solvents are not particularly limited, and include, for example, (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, and dipropylene glycol mono-n-butyl ether; (Poly)alkylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol methyl ether acetate (PGMEA), and propylene glycol ethyl ether acetate; other ethers such as diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, and cyclopentyl methyl ether; ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, 3-heptanone, 4-heptanone, 5-methyl-3-heptanone, 2,4-dimethyl-3-pentanone, and 2,6-dimethyl-4-heptanone; alkyl lactate esters such as methyl 2-hydroxypropionate and ethyl 2-hydroxypropionate;Other esters such as ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutylpropionate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, n-pentyl formate, i-pentyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, i-propyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, and ethyl 2-oxobutanoate; alicyclic hydrocarbons such as cyclohexane, methylcyclohexane, ethylcyclohexane, and dimethylcyclohexane; Aromatic ethers such as anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 3,4-dimethoxytoluene, and 1,4-bis(methoxymethyl)benzene are examples of organic solvents that can be used as component (B). One organic solvent may be used alone, or multiple organic solvents may be used in combination, taking into consideration miscibility with component (A).

[0060] In one embodiment of the present invention, from the viewpoint of further improving the coatability of the polysiloxane composition and forming a high-quality coating film, it is preferable that component (B) contains an organic solvent selected from the group consisting of propylene glycol alkyl ether compounds and alkylcycloalkane compounds. Specific examples of preferred propylene glycol alkyl ether compounds are not particularly limited, but include propylene glycol methyl ether and propylene glycol methyl ether acetate. Specific examples of preferred alkylcycloalkane compounds are not particularly limited, but include methylcyclohexane and ethylcyclohexane.

[0061] In one embodiment of the present invention, from the viewpoint of further improving the coatability of the polysiloxane composition and forming a high-quality coating film, it is particularly preferable that component (B) contains methylcyclohexane. In this embodiment, methylcyclohexane can be used alone as component (B), or a mixed solvent of methylcyclohexane with the other solvents described above can also be used. Here, the other solvent to be mixed with methylcyclohexane is preferably a propylene glycol alkyl ether compound such as propylene glycol methyl ether or propylene glycol methyl ether acetate.

[0062] <<Content of Component (B)>> As described above, the amount of component (B) contained in the polysiloxane composition of the present invention must be 10 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the total mass of components (A) and (B). When the amount of component (B) per 100 parts by mass of the total of components (A) and (B) is within the above-mentioned range, the storage stability and coatability of the polysiloxane composition to a substrate can be ensured. Furthermore, it becomes easier to control the film thickness of a coating film formed from the polysiloxane composition. In one aspect of the present invention, from the viewpoint of further improving the storage stability and coatability of the polysiloxane composition to a substrate, the amount of component (B) contained in the polysiloxane composition of the present invention is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, particularly preferably 50 parts by mass or more, relative to 100 parts by mass of the total mass of components (A) and (B). It is preferably 80 parts by mass or less, and more preferably 70 parts by mass or less.

[0063] In one embodiment of the present invention, the amount of component (B) contained in the polysiloxane composition of the present invention is, from the viewpoint of further improving the storage stability and coatability to a substrate of the polysiloxane composition, preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more, and is preferably 80% by mass or less, and more preferably 70% by mass or less, based on the total mass of the polysiloxane composition being 100% by mass.

[0064] <Other Components> The polysiloxane composition of the present invention may contain other components in addition to the above-described components (A) and (B). In one embodiment of the present invention, the polysiloxane composition may contain a small amount of an organic solvent other than component (B), i.e., at least one of benzene, toluene, ethylbenzene, and xylene. However, from the viewpoint of further improving safety to living organisms, the total amount of benzene, toluene, ethylbenzene, and xylene contained in the polysiloxane composition of the present invention is preferably 1% by mass or less, more preferably 0.5% by mass or less, even more preferably 0.3% by mass or less, particularly preferably 0.1% by mass or less, and most preferably 0% by mass (below the detection limit), based on the total mass of the polysiloxane composition being 100% by mass. In another embodiment of the present invention, the polysiloxane composition may optionally contain an additional additive as component (C). Examples of additives include, but are not limited to, the following:

[0065] <<Adhesion Imparting Agent>> In one embodiment of the present invention, the polysiloxane composition can contain an adhesion imparting agent to improve adhesion to substrates. When the polysiloxane composition of the present invention is used in applications requiring adhesion to substrates, such as coating agents and sealants, it is preferable to add an adhesion imparting agent to the composition of the present invention. As this adhesion imparting agent, any known adhesion imparting agent can be used as long as it does not interfere with the step of removing component (B) from the polysiloxane composition of the present invention. Note that one type of adhesion imparting agent may be used alone, or multiple types may be used in combination.

[0066] The adhesion promoter is not particularly limited, but examples thereof include: organosilanes having a trialkoxysiloxy group (e.g., trimethoxysiloxy group, triethoxysiloxy group) and / or trialkoxysilylalkyl group (e.g., trimethoxysilylethyl group, triethoxysilylethyl group), and a hydrosilyl group and / or an alkenyl group (e.g., vinyl group, allyl group); organosiloxane oligomers having a linear, branched, or cyclic structure and about 4 to 20 silicon atoms, and having a trialkoxysiloxy group and / or trialkoxysilylalkyl group, and a hydrosilyl group and / or an alkenyl group; organosilanes having a trialkoxysiloxy group and / or trialkoxysilylalkyl group, and a methacryloxyalkyl group (e.g., 3-methacryloxypropyl group); Organosiloxane oligomers having a linear, branched, or cyclic structure and having about 4 to 20 silicon atoms, which have a trialkoxysiloxy group and / or a trialkoxysilylalkyl group and a methacryloxyalkyl group; organosilanes having a trialkoxysiloxy group and / 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); organosiloxane oligomers having a linear, branched, or cyclic structure and having about 4 to 20 silicon atoms, which have a trialkoxysiloxy group and / or a trialkoxysilylalkyl group and an epoxy group-bonded alkyl group; organic compounds having two or more trialkoxysilyl groups (e.g., trimethoxysilyl group, triethoxysilyl group); reaction products of aminoalkyltrialkoxysilanes and epoxy group-bonded alkyltrialkoxysilanes; epoxy group-containing ethyl polysilicate;

[0067] More specifically, the adhesion promoter is not particularly limited, but examples thereof include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hydrogentriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 1,6-bis(trimethoxysilyl)hexane, 1,6-bis(triethoxy ...

[0033] Examples of suitable silanol-blocking agents include tris(3-trimethoxysilyl)hexane, 1,3-bis[2-(trimethoxysilyl)ethyl]-1,1,3,3-tetramethyldisiloxane, a reaction product of 3-glycidoxypropyltriethoxysilane and 3-aminopropyltriethoxysilane, a condensation reaction product of a silanol-blocking methylvinylsiloxane oligomer and 3-glycidoxypropyltrimethoxysilane, a condensation reaction product of a silanol-blocking methylvinylsiloxane oligomer and 3-methacryloxypropyltriethoxysilane, and tris(3-trimethoxysilylpropyl)isocyanurate.

[0068] In one embodiment of the present invention, when the polysiloxane composition contains an adhesion promoter, the amount thereof is not particularly limited, but from the viewpoint of suppressing discoloration of a solid material obtained from the composition while sufficiently exhibiting adhesion, the amount thereof is preferably 0.01 parts by mass or more, preferably 5 parts by mass or less, and more preferably 2 parts by mass or less, per 100 parts by mass of component (A).

[0069] <<Other Additives>> In one embodiment of the present invention, other additives may be added to the polysiloxane composition as desired, in addition to or instead of the adhesion promoter described above. Examples of such other additives include, but are not limited to, leveling agents, wettability improvers, silane coupling agents not included in the adhesion promoters described above, high-energy ray absorbers, antioxidants, polymerization inhibitors, fillers (functional fillers such as reinforcing fillers, insulating fillers, hollow fillers, and thermally conductive fillers), and thixotropy-imparting agents. These additives may be used alone or in combination. Thixotropy-imparting agents are particularly useful when the polysiloxane composition of the present invention is used as a sealing material.

[0070] <Method for Preparing Polysiloxane Composition> The method for preparing the polysiloxane composition of the present invention is not particularly limited. For example, the polysiloxane composition of the present invention can be prepared by mixing component (A) and component (B), as well as other components used as needed, using a known method.

[0071] (Use of Polysiloxane Composition) The use of the polysiloxane composition of the present invention is not particularly limited. In one embodiment of the present invention, the polysiloxane composition can be used as an insulating coating agent, and an insulating coating can be formed using the polysiloxane composition. In another embodiment of the present invention, a display device can include a layer made of a solid material formed using the polysiloxane composition.

[0072] The processing method of the polysiloxane composition of the present invention for various uses will be described below. In one embodiment of the present invention, the processing method of the polysiloxane composition includes a step of applying the polysiloxane composition to a substrate (hereinafter referred to as the "application step") and a step of removing component (B) from the polysiloxane composition on the substrate (hereinafter referred to as the "organic solvent removal step").

[0073] In the coating step, the method for coating the polysiloxane composition onto the substrate is not particularly limited, and any known method using a coating device such as a spin coater, roll coater, bar coater, slit coater, etc. The type of substrate is also not particularly limited, and any known substrate such as a silicon wafer can be used depending on the application of the polysiloxane composition.

[0074] In the organic solvent removal step, the method for removing component (B) from the polysiloxane composition is not particularly limited. In one embodiment of the present invention, component (B) can be removed by drying with heat. By heating the polysiloxane composition applied to a substrate, the organic solvent, component (B), is dried and removed, yielding a solid product such as a coating film. The heating method and conditions are not particularly limited, but examples include drying on a hot plate or in an oven at a temperature of 80 to 120°C, preferably 90 to 110°C, for 1 to 5 minutes; leaving the composition at room temperature for several hours; and heating in a hot air heater or infrared heater for several tens of minutes to several hours. Note that when the polysiloxane composition of the present invention contains at least one organic solvent, such as benzene, toluene, ethylbenzene, or xylene, it is preferable to remove the organic solvent along with component (B) in the organic solvent removal step. The solid product obtained through the organic solvent removal step can be used directly for any application, such as insulating coating. Furthermore, in the organic solvent removal step, it is also possible to react the reactive groups (OZ groups) remaining in the branched polysiloxane molecules by extending the heating time and / or increasing the heating temperature (for example, 200 to 250°C). By such treatment, a solid product with an increased specific gravity can be obtained.

[0075] In the present invention, the viscosity of the polysiloxane composition and / or the rate of production of a solid formed using the polysiloxane composition can be controlled by changing the structure, boiling point, and / or amount of the organic solvent used as component (B). Furthermore, in the present invention, the desired refractive index and mechanical properties of the solid can be designed by changing the molecular structure of the branched polysiloxane used as component (A) and / or the ratio of remaining reactive groups (OZ groups). The shape of the solid (branched polysiloxane solid) obtained by removing component (B) from the polysiloxane composition disclosed as one embodiment of the present invention is not particularly limited and may be a thin-film coating or a molded product such as a sheet. In one embodiment of the present invention, the solid may be used as a sealant or intermediate layer for laminates or display devices. In another embodiment of the present invention, the solid is preferably in the form of a thin-film coating, and more preferably a thin-film insulating coating. Such insulating coatings are particularly useful, for example, as materials for forming insulating layers constituting electronic and electrical devices.

[0076] Furthermore, since the solid formed using the polysiloxane composition of the present invention has good transparency, an insulating coating made of the solid is suitable as a material for forming an insulating layer in a display device such as a touch panel or a display. In this case, the insulating layer may be formed into any desired pattern as needed. Therefore, a display device such as a touch panel or a display, which includes an insulating layer made of a solid formed using the polysiloxane composition of the present invention, can also be cited as an embodiment of the present invention.

[0077] The present invention will be further described below based on examples, but the present invention is not limited to the following examples. The following methods were employed for various measurements and evaluations.

[0078] <Appearance of Polysiloxane Composition and Obtained Solid> The polysiloxane composition and the obtained solid were visually observed, and the appearance including transparency was evaluated.

[0079] <Average Composition Formula, Average Unit Formula, and Silanol Group Content of Branched Polysiloxane> Deuterated acetone was used as a solvent. １３ C-NMR and ２９ The molar concentrations of each siloxane unit and silanol group were calculated by Si-NMR spectroscopy, and the average composition formula, average unit formula, and silanol group content were identified.

[0080] <Molecular Weight and PDI of Branched Polysiloxane> Gel permeation chromatography (GPC) analysis was performed using tetrahydrofuran as an eluent to measure the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of standard polystyrene. From these values, the PDI (Mw / Mn) was calculated.

[0081] <Storage Stability of Polysiloxane Composition> The viscosity η0 of the prepared polysiloxane composition was measured at 25°C using a Brookfield viscometer in accordance with JIS K7117-1. After measuring the viscosity η0, the polysiloxane composition was stored in a refrigerator at 5°C for 30 days, and the viscosity η1 after storage was measured in the same manner as for η0. The viscosity increase rate (%) = (η1 - η0) / η0 × 100 was calculated, and the storage stability was evaluated according to the following criteria. A smaller viscosity increase rate value indicates better storage stability of the polysiloxane composition. A: Viscosity increase rate is 10% or less B: Viscosity increase rate is more than 10% and less than 30% C: Viscosity increase rate is more than 30%

[0082] <Coating Properties of Polysiloxane Composition> The prepared polysiloxane composition was spin-coated onto a silicon wafer substrate to a thickness of 4 μm. The polysiloxane composition on the substrate was heated in an oven at 100° C. for 5 minutes to form a coating film. This coating film was inspected and evaluated according to the following criteria: A: No coating unevenness, coating thickness uniform; B: Coating unevenness was observed in parts (5% or less of the total coating area), but the coating thickness was approximately uniform enough to cause no problems in practical use; C: Coating unevenness was observed over a wide area (more than 5% of the total coating area), causing problems in practical use.

[0083] <Tackiness (surface tackiness) of coating film surface formed using polysiloxane composition> A coating film was formed on a silicon wafer in the same manner as in "Coating property of polysiloxane composition". The surface of this coating film was touched with a finger to evaluate the surface tackiness. A: No tackiness B: Slight tackiness was observed, but the liquid did not adhere to the finger C: Severe tackiness was observed, and the liquid adhered to the finger

[0084] <Refractive index of branched polysiloxane> A coating film was formed on a silicon wafer in the same manner as in "Coating property of polysiloxane composition." The refractive index of this coating film made of branched polysiloxane at a wavelength of 633 nm was measured under the following conditions. Measuring device: Film thickness / refractometer "Model 2010 / M Prism Coupler" (manufactured by Metricon) Measurement temperature: Room temperature (25°C)

[0085] Synthesis Example 1: Branched Polysiloxane (A-1) A 500 mL three-neck flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube was charged with 68.1 g of methyltrimethoxysilane and 82.0 g of n-propyltrimethoxysilane as starting materials, 0.54 g of oxalic acid as an acidic catalyst, 48 g of water, and 135 g of PGMEA as a reaction solvent. This mixture was refluxed at 70°C in an oil bath for 2 hours to carry out a hydrolysis and condensation reaction. Methanol and excess water were removed from the resulting reaction solution by raising the bath temperature to 100°C. The reaction solution was then cooled to 50°C or below, and 3 g of an adsorbent (Kyowa Chemical Industry Co., Ltd., "KW-2000") was added, followed by stirring at the same temperature for 30 minutes. The solid was filtered off, and the volatile components were removed by distillation under reduced pressure to obtain a colorless PGMEA solution of branched polysiloxane (A-1). The obtained branched polysiloxane (A-1) is １３ C and ２９Analysis was performed by SiNMR spectroscopy and gel permeation chromatography (GPC). As a result, it was confirmed that the branched polysiloxane (A-1) was a poly(methyl-propyl)silsesquioxane copolymer with a methyl group / n-propyl group molar ratio of 50 / 50. Furthermore, the amount of OZ groups was 0.53 mol per mol of silicon atoms, and the amount of silanol groups was 0.48 mol per mol of silicon atoms. The Mw was 2,900, and the PDI was 3.0.

[0086] From the above results, it was found that the branched polysiloxane (A-1) had the following average composition formula and the following average unit formula: <<Average composition formula>> (n-C3H7) 0.5 (CH ３ ) 0.5 (OH) 0.48 (OCH ３ ) 0.05 SiO 1.235 <<Average unit formula>> ((CH3)SiO 3 / 2 ) 0.5 ((n-C3H7)SiO 3 / 2 ) 0.5 (OH) 0.48 (OCH ３ ) 0.05

[0087] Synthesis Example 2: Branched Polysiloxane (A-2) A colorless PGMEA solution of branched polysiloxane (A-2) was obtained in the same manner as in Synthesis Example 1, except that the mixing ratio of methyltrimethoxysilane and n-propyltrimethoxysilane used as starting materials was changed. The obtained branched polysiloxane (A-2) was analyzed in the same manner as in Synthesis Example 1. As a result, it was confirmed that branched polysiloxane (A-2) was a poly(methyl-propyl)silsesquioxane copolymer with a methyl group / n-propyl group molar ratio of 25 / 75. Furthermore, the amount of OZ groups was 0.39 mol per mole of silicon atoms, and the amount of silanol groups was 0.35 mol per mole of silicon atoms. The Mw was 1,540, and the PDI was 2.2.

[0088] From the above results, it was found that the branched polysiloxane (A-2) had the following average compositional formula and the following average unit formula: <<Average compositional formula>> (n-C3H7) 0.75 (CH ３ ) 0.25 (OH) 0.35 (OCH ３ ) 0.04 SiO 1.305 <<Average unit formula>> ((CH3)SiO 3 / 2 ) 0.25 ((n-C3H7)SiO 3 / 2 ) 0.75 (OH) 0.35 (OCH3) 0.04

[0089] Synthesis Example 3: Branched Polysiloxane (A-3) A 300 mL three-neck flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube was charged with 33.4 g of methyltrimethoxysilane, 45.5 g of n-propyltrimethoxysilane, and 7.5 g of hexamethyldisiloxane as starting materials, 87 g of methylcyclohexane as a reaction solvent, and 1.2 g of hydrochloric acid as an acid catalyst (as hydrogen chloride, in an amount equivalent to 500 ppm of the total silicon raw material). This mixture was stirred at 60 ° C. in an oil bath for 2 hours to carry out a hydrolysis and condensation reaction. The resulting reaction solution was cooled to 30 ° C. or below, and an aqueous potassium hydroxide solution as a basic catalyst (as potassium hydroxide after neutralization, in an amount equivalent to 1000 ppm of the total silicon raw material) was added, followed by stirring for an additional 30 minutes. The bath temperature was raised to 100 ° C., methanol and excess water were removed, and the mixture was further stirred at an internal temperature of 90 ° C. for 1 hour. After cooling the reaction solution to below 50°C, 2 g of an adsorbent (Kyoward (registered trademark) 700PL) was added and the mixture was stirred at the same temperature for 30 minutes. The solid was filtered off, and the volatile components were removed by distillation under reduced pressure to obtain a colorless methylcyclohexane solution of branched polysiloxane (A-3). The resulting branched polysiloxane (A-3) was analyzed in the same manner as in Synthesis Example 1. As a result, it was confirmed that branched polysiloxane (A-3) was a poly(trimethylsiloxane / methylsiloxane / n-propylsiloxane) copolymer with a molar ratio of trimethylsilyl groups / methylsilyl groups / n-propylsilyl groups of 15 / 40 / 45. The amount of OZ groups was 0.03 mol% per mole of silicon atoms, and the amount of silanol groups was 0.03 mol% per mole of silicon atoms. The Mw was 18,800, and the PDI was 9.3.

[0090] From the above results, it was found that the branched polysiloxane (A-3) had the following average compositional formula and the following average unit formula: <<Average compositional formula>> (n-C3H7) 0.45 (CH3) 0.85 (OH) 0.03 SiO 1.335 <<Average unit formula>> ((CH3)3SiO 1 / 2 ) 0.15 ((CH3)SiO 3 / 2 ) 0.40 ((n-C3H7)SiO3 / 2 ) 0.45 (OH) 0.03

[0091] Synthesis Example 4: Branched Polysiloxane (A-4) A colorless PGMEA solution of branched polysiloxane (A-4) was obtained in the same manner as in Synthesis Example 1, except that instead of 68.1 g of methyltrimethoxysilane, 82.0 g of n-propyltrimethoxysilane, 135 g of PGMEA, 0.54 g of oxalic acid, and 48 g of water, 187.5 g of methyltrimethoxysilane as the starting material, 0.68 g of oxalic acid as the acidic catalyst, 369 g of PGMEA as the reaction solvent, and 67.5 g of water were charged into a 1000 mL three-neck flask. The obtained branched polysiloxane (A-4) was analyzed in the same manner as in Synthesis Example 1. As a result, it was confirmed that the branched polysiloxane (A-4) was polymethylsilsesquioxane. The amount of OZ groups was 0.49 mol per mol of silicon atom, the amount of silanol groups was 0.44 mol per mol of silicon atom, Mw was 3,000, and PDI was 2.6.

[0092] Synthesis Example 5: Branched Polysiloxane (A-5) A colorless PGMEA solution of branched polysiloxane (A-5) was obtained in the same manner as in Synthesis Example 1, except that 226.1 g of n-propyltrimethoxysilane as the starting material, 0.80 g of oxalic acid as the acidic catalyst, 440 g of PGMEA as the reaction solvent, and 81.4 g of water were charged into a 1000 mL three-neck flask instead of 68.1 g of methyltrimethoxysilane, 82.0 g of n-propyltrimethoxysilane, 135 g of PGMEA, 0.54 g of oxalic acid, and 48 g of water. The obtained branched polysiloxane (A-5) was analyzed in the same manner as in Synthesis Example 1. As a result, it was confirmed that the branched polysiloxane (A-5) was poly-n-propylsilsesquioxane (A-5). The amount of OZ groups was 0.49 mol per mol of silicon atom, the amount of silanol groups was 0.44 mol per mol of silicon atom, Mw was 1,000, and PDI was 1.3.

[0093] Examples 1 to 3 and Comparative Examples 1 to 4 Polysiloxane compositions were prepared by mixing (A) a branched polysiloxane, (B) an organic solvent, and, if necessary, (C) an additive, in amounts of parts by mass as shown in Table 1. Coating films were then formed from the polysiloxane compositions, and various evaluations were carried out for the above-mentioned items. All of the results are shown in Table 1. Table 1 also shows the values ​​of b and c in the average composition formula (1), as well as the amount of silanol groups.

[0094] The terms in Table 1 below have the following meanings. [b]: the value of b in the average composition formula (1) [c]: the value of c in the average composition formula (1) [Silanol]: the content of silanol groups (Si—OH) per mole of silicon atoms in the branched polysiloxane (unit: moles) A-1: ​​branched polysiloxane (A-1) obtained in Synthesis Example 1 A-2: branched polysiloxane (A-2) obtained in Synthesis Example 2 A-3: branched polysiloxane (A-3) obtained in Synthesis Example 3 A-4: branched polysiloxane (A-4) obtained in Synthesis Example 4 A-5: branched polysiloxane (A-5) obtained in Synthesis Example 5 A-6: methoxy-functional polymethylsilsesquioxane (DOWSIL (registered trademark) 2402 manufactured by The Dow Chemical Company) A-7: Methoxy-functional poly(dimethylsiloxy / methylsiloxy) copolymer ("DOWSIL 2405" manufactured by The Dow Chemical Company) B-1: Propylene glycol methyl ether acetate (PGMEA) B-2: Methylcyclohexane C-1: Dimethyl silicone oil (wettability improver, "DOWSIL SH 200 Fluid 20 cS" manufactured by The Dow Chemical Company)

[0095]

[0096] The polysiloxane compositions of Examples 1 to 3 exhibited good storage stability, good coatability on silicon wafers, and were capable of forming uniform coating films. Furthermore, the refractive index (branched polysiloxane solids) of the coating films obtained from the polysiloxane compositions of Examples 1 to 3 was low, less than 1.45. Furthermore, the surfaces of the coating films obtained from the polysiloxane compositions of Examples 1 to 3 were free of tackiness, and the coating films exhibited excellent transparency. On the other hand, the polysiloxane compositions of Comparative Examples 1 to 4, which contained branched polysiloxanes whose structural factors did not satisfy the required conditions, were unable to achieve both storage stability and coatability. Specifically, in Comparative Examples 1, 2, and 4, which used branched polysiloxanes with b×c values ​​exceeding 0.4, the storage stability or coatability of the polysiloxane compositions to substrates deteriorated. Furthermore, in Comparative Example 3, which used a branched polysiloxane in which b=0 and b×c=0, the refractive index of the coating film obtained from the polysiloxane composition was high, and the composition was unable to be fully utilized as a low-refractive-index material.

[0097] According to the present invention, it is possible to provide a polysiloxane composition capable of forming a coating film having a low refractive index and exhibiting excellent storage stability and applicability to substrates, and uses thereof. Furthermore, the coating film formed using the polysiloxane composition of the present invention is of high quality, tack-free, and exhibits a low refractive index. Furthermore, the coating film formed using the resulting polysiloxane composition of the present invention has the advantage of being excellent in mechanical strength and transparency. Therefore, the polysiloxane composition of the present invention is useful as an insulating material for electric and electronic devices such as display devices. The polysiloxane composition of the present invention is also useful as an insulating coating agent, an anti-reflective coating material, and the like.

Claims

1. (A) The following average composition formula (1): R Ａ ａ R ｂ (OZ) ｃ SiO （４－ａ－ｂ－ｃ）／２ (1) (In formula (1), R Ａ 0<b≦1.5; 0<c<0.8; 0.5<a+b≦1.8; 0<b×c≦0.

4. A polysiloxane composition comprising: (A) a branched polysiloxane having a refractive index of less than 1.45 at a wavelength of 633 nm, and (B) an organic solvent other than benzene, toluene, ethylbenzene, and xylene; and (C) an organic solvent other than benzene, toluene, ethylbenzene, and xylene; and (D) a branched polysiloxane having a refractive index of less than 1.45 at a wavelength of 633 nm, and (E) a branched polysiloxane having a refractive index of less than 1.45 at a wavelength of 633 nm, and (F) an organic solvent other than benzene, toluene, ethylbenzene, and xylene; and (G) a branched polysiloxane having a refractive index of less than 1.45 at a wavelength of 633 nm, and (H) a branched polysiloxane having a refractive index of less than 1.45 at a wavelength of 633 nm.

2. The polysiloxane composition according to claim 1, wherein Z in said average composition formula (1) contains a hydrogen atom.

3. R ​​in the average composition formula (1) Ａ The polysiloxane composition of claim 1 , wherein comprises an n-propyl group.

4. The polysiloxane composition according to claim 1, wherein R in said average composition formula (1) contains a methyl group and does not contain a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms.

5. The polysiloxane composition according to claim 1, wherein the component (A) is a branched polysiloxane represented by the following average unit formula (2): (R ３ SiO １／２ ) ｋ１ (R Ａ R ２ SiO １／２ ) ｋ２ (R ２ SiO ２／２ ) L１ (R Ａ RSiO ２／２ ) L２ (RSiO ３／２ ) ｍ１ (R Ａ SiO ３／２ ) ｍ２ (SiO ４／２ ) ｎ (Z.O. １／２ ) ｚ (2) (In formula (2), R Ａ , R, and Z have the same meaning as above, 0≦k1+k2≦0.5, 0≦L1+L2≦0.5, 0<m1+m2≦1, 0≦n≦0.6, 0<z<0.8, k1+k2+L1+L2+m1+m2+n=1, and 0<(3×k1+2×k2+2×L1+L2+m1)×z≦0.

4.

6. The polysiloxane composition according to claim 5, wherein k2, L1, L2, and n in the average unit formula (2) are all 0, and 0<m2.

7. The polysiloxane composition according to claim 1, wherein said component (B) comprises at least one selected from the group consisting of propylene glycol alkyl ether compounds and alkylcycloalkane compounds.

8. The polysiloxane composition of claim 1, wherein said component (B) comprises at least one selected from the group consisting of propylene glycol methyl ether, propylene glycol methyl ether acetate, methylcyclohexane, and ethylcyclohexane.

9. The polysiloxane composition of claim 1, wherein said component (B) comprises methylcyclohexane.

10. An insulating coating agent comprising the polysiloxane composition according to any one of claims 1 to 9.

11. An insulating coating formed using the polysiloxane composition according to any one of claims 1 to 9.

12. A method for producing an insulating coating, comprising the step of removing said component (B) from the polysiloxane composition according to any one of claims 1 to 9.

13. A display device comprising a layer made of a solid material formed using the polysiloxane composition according to any one of claims 1 to 9.

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