Ester dispersed silica sol and method for producing the same

Abstract

The objective of this invention is to provide a silica sol using a carboxylic acid ester as a dispersion medium and a method for manufacturing the same. The solution is a silica sol containing Si-OR particles on or near the surface of silane-treated silica particles. 1 (where R) 1 This indicates an organic group that can have 2 to 10 carbon atoms and contain oxygen atoms. The silica particles, represented by the alkoxy group, are used as a dispersion medium containing an alkoxy group with R... 2 -COO-R 1 Structure (where R) 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 This indicates that the solvent of a carboxylic acid ester (containing alkyl groups with 1 to 10 carbon atoms and oxygen atoms) can be used as the dispersion medium, and it also contains an amine. The above dispersion is in the presence of Si-OR 0 and Si-OR 1 (where R) 0 It is an alkyl group having 1 to 4 carbon atoms, R 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 0 With R 1 Not the same chemical group. At least two alkoxy groups, and (Si-OR) 1 ) / (Si-OR 0 The silicon dioxide particles contained in the Si-OR at a molar ratio of 0.002 to 50. 0 The particles are Si-OCH3 or Si-OC2H5. The average particle size obtained by dynamic light scattering is 5–200 nm.

Description

Technical Field

[0001] This invention relates to silica sol dispersed in carboxylic acid esters and its manufacturing method. Background Technology

[0002] Attempts were made to improve the properties of the film by including silica particles in the resin or the coating composition for the film, and to improve the properties of the cured product by including silica particles in the resin matrix. They used dispersions of colloidal silica (silica sol), but to improve compatibility with organic materials, silica sol dispersed in a non-aqueous solvent (organic silica sol) was used.

[0003] A method for manufacturing an organic solvent-dispersed inorganic oxide sol, including, for example, the steps (A) and (B) described below, is disclosed (see Patent Document 1):

[0004] (A) A step of surface-treating inorganic oxide particles in a sol containing 25-100% by mass of a hydrophilic inorganic oxide sol with a boiling point below 100°C in a dispersion medium by adding a silanolate having two or more alkoxy groups bonded to silicon atoms, or a silanolate having one or more hydroxyl groups bonded to silicon atoms and one or more alkoxy groups bonded to silicon atoms; and

[0005] (B) A process in which the dispersion medium of the surface-treated inorganic oxide sol obtained in step (A) is replaced with a non-alcoholic organic solvent in the presence of primary alcohols with 3 to 12 carbon atoms.

[0006] This method discloses a process of reacting hydroxyl groups on the surface of inorganic oxide particles, such as silica, with alcohols to introduce alkoxy groups for organication, thereby obtaining an inorganic oxide sol dispersed in an organic solvent such as toluene. For example, it discloses a silica sol dispersed in toluene solvent by reacting phenyltrimethoxysilane with methanol to form a silica sol.

[0007] A silica sol is disclosed, which is a sol (silica sol) in which silica particles with an average particle size of 5-100 nm, containing unsaturated organic groups and alkoxy groups containing carbon atoms bonded to the surface, are dispersed in a ketone-based solvent. The unsaturated organic groups containing carbon atoms are arranged at a concentration of 0.5-2.0 atoms / nm. 2 In combination, alkoxy groups are present at a concentration of 0.1–2.0 per nm. 2 They are combined, and in a molar ratio of (organic groups containing unsaturated bonds between carbon atoms) / (alkoxy groups) = 0.5 to 5.0 (see Patent Document 2).

[0008] A method for manufacturing hydrophobic silica sol with an increased pH value by treating it with an alkali in the acidic region is disclosed (see Patent Document 3).

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2005-200294

[0012] Patent Document 2: International Publication No. 2020-230823

[0013] Patent Document 3: Japanese Patent Application Publication No. 4-092808 Summary of the Invention

[0014] The problem that the invention aims to solve

[0015] The present invention aims to provide a silica sol using carboxylic acid esters as a dispersion medium and a method for manufacturing the same. The organosilica sol of the present invention can undergo silane treatment on the surface of silica particles, thereby providing a silica sol with improved stability through the addition of amines.

[0016] Methods for solving problems

[0017] In this invention, as a first aspect, there is a silica sol containing Si-OR on or near the surface of silica particles treated with silane. 1 (where R) 1 This indicates an organic group that can have 2 to 10 carbon atoms and contain oxygen atoms. The silica particles, represented by the alkoxy group, are used as a dispersion medium containing an alkoxy group with R... 2 -COO-R 1 Structure (where R) 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 This indicates that the solvent for carboxylic acid esters (which can be alkyl groups with 1 to 10 carbon atoms and may contain oxygen atoms) is used as the dispersion medium, and also contains amines.

[0018] As a second point of view, based on the silica sol described in the first point of view, the aforementioned dispersion consists of Si-OR particles present on or near the surface of silica particles treated with silane. 0 and Si-OR 1 (where R) 0 R represents an organic group that can have 1 to 10 carbon atoms and may contain oxygen atoms. 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 0 With R 1Not the same chemical group. At least two alkoxy groups are shown, and in (Si-OR) 1 ) / (Si-OR 0 The molar ratio of the silica particles contained in the silica is 0.002 to 50.

[0019] As a third point of view, based on the silica sol described in the first or second point of view, the average particle size of the silica particles obtained by dynamic light scattering method is 5–200 nm.

[0020] As a fourth point of view, based on the silica sol described in the first or second point of view, R 1 It can be ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 1-methoxy-2-propyl, 1-ethoxy-2-propyl, or phenyl.

[0021] As the fifth point of view, it is a silica sol based on any one of the first to fourth points of view, R 2 It is methyl, ethyl, or propyl.

[0022] As a sixth point of view, based on any one of the first to fifth points of view, the silane treatment of the aforementioned silica particles is carried out by a hydrolysate of at least one silane compound selected from formulas (1) to (3).

[0023] R 3 a Si(R 4 ) 4-a Equation (1)

[0024] [R] 5 b Si(R 6 ) 3-b 2Y c Equation (2)

[0025] R 7 d Si(R 8 ) 4-d Equation (3)

[0026] (In equation (1), R) 3 They are alkyl, haloalkyl, alkenyl, aryl, or organic groups having an epoxy, (meth)acryloyl, mercapto, amino, urea, or cyano group, and are bonded to silicon atoms via Si-C bonds. 4 These represent alkoxy, acyloxy, or halogen groups, respectively, with 'a' representing an integer from 1 to 3.

[0027] In equations (2) and (3), R 5 and R 7They are alkyl groups with 1 to 3 carbon atoms or aryl groups with 6 to 30 carbon atoms, and are bonded to silicon atoms via Si-C bonds. 6 and R 8 These represent alkoxy, acyloxy, or halogroups, respectively; Y represents alkylene, NH group, or oxygen atom; b is an integer from 1 to 3; c is an integer 0 or 1; and d is an integer from 1 to 3.

[0028] As a seventh point of view, based on the silica sol described in the first or second point of view, the aforementioned amine is a secondary or tertiary amine with a total carbon number of 5 to 35.

[0029] As the eighth point of view, based on the silica sol described in the seventh point of view, the pH of the liquid obtained by mixing silica sol containing the aforementioned amine with methanol and pure water in a mass ratio of 1:1:1 to 1:2:1 is 4.0 to 9.5.

[0030] As the ninth point of view, the method for manufacturing silica sol according to any one of the first to eighth points of view includes the following steps (A) to (B), and from the end of step (A) to the end of step (B), it includes the following step (A-1), and the following step (A-2) after the end of step (A-1).

[0031] (A) Process: Obtaining silica particles with an average particle size of 5–200 nm obtained by dynamic light scattering as the dispersion phase, and using alcohol R 0 OH (where R) 0 This refers to an organic group that can have 1 to 10 carbon atoms and contain oxygen atoms. (The process involves using silica sol as a dispersion medium.)

[0032] (B) Process: Performing R to remove the silica sol obtained in (A) process. 0 Part of OH, all of it, and the addition of R 2 -COO-R 1 Structure (where R) 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 The process of producing carboxylic acid esters (representing alkyl groups with 1 to 10 carbon atoms).

[0033] (A-1) Step: A step of treating the silica particles contained in the silica sol obtained in step (A) with at least one silane compound shown in formulas (1) to (3) above.

[0034] (A-2) Step: The step of adding a secondary or tertiary amine with a total carbon number of 5 to 35 to the silica sol obtained in step (A-1); and

[0035] As the tenth point of view, the method for manufacturing silica sol according to the ninth point of view, the above-mentioned step (A) involves obtaining silica particles with an average particle size of 5 to 200 nm obtained by dynamic light scattering as the dispersion medium, and using alcohol R... 0 OH (where R) 0 This refers to an organic group that can have 1 to 10 carbon atoms and contain oxygen atoms. (The process involves using silica sol as a dispersion medium.)

[0036] Step (B) above involves removing the alcohol R from the silica sol obtained in step (A). 0 Part of OH, all of it, and the addition of R 2 -COO-R 1 Structure (where R) 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 R represents an alkyl group having 1 to 10 carbon atoms. 0 With R 1 The process of carboxylic acid esters (not the same chemical group).

[0037] The effects of the invention

[0038] Ester solvents, especially carboxylic acid esters, are valued for their environmental properties, such as low odor and low toxicity, leading to increased demand as alternatives to hydrocarbon and ketone solvents. For solvents used extensively in applications such as dilution in coatings, inks, and adhesives, as well as in pharmaceutical / pesticide reaction solvents, derivative raw materials, and detergents, the replacement of ketone solvents with ester solvents and the establishment of solvent recycling systems offer significant potential benefits.

[0039] On the other hand, attempts were made to improve the physical properties of the film by including silica particles in the resin or the coating composition for the film, and to improve the physical properties of the cured product by including silica particles in the resin matrix.

[0040] In various applications where performance is sought to be improved by including silica particles, since colloidal particles are used, agglomeration is inevitable if silica powder is used. Therefore, silica particles are added to resins, etc., in the form of colloidal silica dispersion (silica sol). In this case, silica sol dispersed in an organic solvent with high compatibility with the resin is used.

[0041] In this invention, a silica sol is provided that is dispersed in a carboxylic acid ester solvent with high utilization value as a solvent.

[0042] Organic silica sols are typically produced by dispersing silica sols in an aqueous solvent (aqueous silica sols), replacing the dispersion medium with a lower alcohol (e.g., methanol), and further replacing the solvent with the target carboxylic acid ester, thereby obtaining a silica sol with a carboxylic acid ester as the dispersion medium.

[0043] In this invention, it was discovered that the dispersion stability of the carboxylic ester solvent is improved by having a group containing a chemical group adjacent to the ester group of the carboxylic ester present as an alkoxy group on or near the surface of the silica particles.

[0044] Through the organic group (R) adjacent to the ester group of the carboxylic acid ester on or near the surface of silica particles. 1 The group (Si-OR) is converted into a silanol group (Si-OR) through transesterification. 1 The presence of (base) results in silica particles with high dispersibility in ester solvents.

[0045] Furthermore, it is known that silica particles, by having silanol groups on their surface, can replace the dispersion medium from water to, for example, methanol, thereby converting the hydroxyl groups of the silanols into methoxy groups. Additionally, by replacing the dispersion medium from methanol to a carboxylic acid ester, the silanol groups on or near the surface of the silica particles are replaced with at least two alkoxy groups through an ester-exchange reaction between the aforementioned methoxy groups and the carboxylic acid ester. For example, at least two alkoxy groups are present, including a methoxy group and an alkoxy group formed from the organic group of the ester.

[0046] The presence ratio of at least two alkoxy groups significantly affects the stability of silica sols using carboxylic acid esters as the dispersion medium.

[0047] Since transesterification is readily promoted on the acidic side, and the hydrolysis of alkoxy groups is also readily promoted on the acidic side, the dispersion medium is preferably maintained on the alkaline side, for example, by containing amine compounds.

[0048] Silica sol using carboxylic acid esters as the dispersion medium is treated with silane compounds on the surface of silica particles to covalently bind the functional groups that have not been converted into silanols, thereby contributing to the stability of silica sol using carboxylic acid esters as the dispersion medium. Detailed Implementation

[0049] This invention relates to a silica sol containing Si-OR on or near silica particles that have undergone silane treatment. 1 (where R) 1 This refers to an organic group containing alkoxy groups (2 to 10 carbon atoms, representing oxygen atoms) as a dispersion medium, containing alkoxy groups. 2 -COO-R 1 Structure (where R) 1R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 This indicates that the solvent of a carboxylic acid ester (containing alkyl groups with 1 to 10 carbon atoms and oxygen atoms) can be used as the dispersion medium, and it also contains an amine.

[0050] Furthermore, the present invention is a silica sol containing Si-OR on or near the surface of silica particles treated with silane. 0 and Si-OR 1 (where R) 0 This refers to an organic group that can have 1 to 10 carbon atoms and may contain oxygen atoms, further R 0 R represents an alkyl group having 1 to 4 carbon atoms. 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 0 With R 1 Not the same chemical group. At least two alkoxy groups, and in the form of (Si-OR) 1 ) / (Si-OR 0 The silica particles contained in the mixture at a molar ratio of 0.002 to 50 are used as a dispersion phase, and contain R... 2 -COO-R 1 Structure (where R) 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 This indicates that the solvent of a carboxylic acid ester (containing alkyl groups with 1 to 10 carbon atoms and oxygen atoms) can be used as the dispersion medium, and it also contains an amine.

[0051] The above (Si-OR) 1 ) / (Si-OR 0 The molar ratio can be in the range of 0.002 to 50 or 0.01 to 40.

[0052] In the aforementioned Si-OR 0 and Si-OR 1 In the middle, R 0 With R 1 They are not the same chemical groups. That is, if Si-OR 0 If it is Si-OCH3, then Si-OR 1 Chinese R 1 It refers to an organic group other than methyl that can have 2 to 10 carbon atoms and contain oxygen atoms.

[0053] In addition, the number of carbon atoms can also have R. 0 <R 1 The relationship between the number of carbon atoms and R. 0 <R 1 The relationship is represented in Si-OR 0 and Si-OR1 In the relationship, if Si-OR 0 If it is Si-OCH3, then Si-OR 1 Chinese R 1 An organic group having more than one carbon atom (ethyl) is an organic group that can have 10 carbon atoms, ranging from ethyl to an organic group that can have oxygen atoms.

[0054] The above Si-OR 0 With Si-OR 1 The alkoxy group is generated by the reversible reaction of the hydroxyl groups of silanol groups on the surface of silica particles with the alcohol when the aqueous medium used as the dispersion medium of aqueous silica sol is replaced with an alcohol.

[0055] The above Si-OR 0 It can represent, for example, Si-OCH3, Si-OC2H5, Si-OC3H7. More preferably, it is Si-OCH3 or Si-OC2H5, and Si-OCH3 is particularly preferred.

[0056] In addition, the aforementioned Si-OR 1 Base (where R) 1 This refers to an organic group with 2 to 10 carbon atoms that can have oxygen atoms. (This is used when an alcohol in the dispersion medium is replaced with R.) 2 -COO-R 1 When the structure of a carboxylic acid ester is determined by Si-OR 1 With R 2 -COO-R 1 The alkoxy group is obtained by a reversible transesterification reaction between the two. In the above R... 1 When the organic groups are the same, Si-OR is formed on or near the surface of the silica particles. 1 base.

[0057] Furthermore, the present invention is a silica sol containing Si-OR on or near the surface of silane-treated silica particles. 0 (R 0 Alkyl groups having 1 to 4 carbon atoms and Si-OR 1 (where R) 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 0 With R 1 Not the same chemical group. At least two alkoxy groups are shown, and in (Si-OR) 1 ) / (Si-OR 0 The molar ratio of (Si-OR) is 0.002 to 50, especially with (Si-OR) 1The silica particles contained in a molar ratio of 0.002 to 50 (Si-OCH3) are used as a dispersion, and contain R... 2 -COO-R 1 Structure (where R) 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 This indicates that the solvent of a carboxylic acid ester (containing alkyl groups with 1 to 10 carbon atoms and oxygen atoms) can be used as the dispersion medium, and it also contains an amine.

[0058] The above Si-OR 0 (Especially Si-OCH3) refers to the hydroxyl groups of silanol groups on the surface of silica particles, which are replaced by R in the aqueous medium used as the dispersion medium for aqueous silica sol. 0 OH with R 0 OH is an alkoxy group produced through a reversible reaction.

[0059] In addition, the aforementioned Si-OR 1 Base (where R) 1 This refers to an organic group that can have 2 to 10 carbon atoms and contain oxygen atoms. (R is used in the dispersion medium.) 0 OH (especially methanol) is replaced by R 2 -COO-R 1 When the structure of a carboxylic acid ester is determined by Si-OR 0 With R 2 -COO-R 1 Alkyl groups are obtained from reversible transesterification reactions between them.

[0060] In this invention, (Si-OR) is preferred. 1 ) / (Si-OR 0 The molar ratio of (Si-OR) is 0.002 to 50, especially (Si-OR) 1 The molar ratio of (Si-OCH3) to (Si-OCH3) is between 0.002 and 50.

[0061] With R 2 -COO-R 1 R of the structure of carboxylic acid ester 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 This refers to an alkyl group having 1 to 10 carbon atoms that can have oxygen atoms. The oxygen atoms can exist in the form of ether bonds or hydroxyl groups.

[0062] The above R 1Examples include ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, 1-methoxy-2-propyl, 1-ethoxy-2-propyl, 1-propoxy-2-propyl, 2-ethoxyethyl, 2-hydroxyethyl, 1-hydroxy-2-ethyl, 3-methoxybutyl, phenyl, etc. 1 Ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, 1-methoxy-2-propyl, 1-ethoxy-2-propyl, and phenyl can be preferred.

[0063] The above R 2 Examples include methyl, ethyl, 1-hydroxyethyl, propyl, etc. R 2 Methyl, ethyl, and propyl groups can be preferred.

[0064] With R 2 -COO-R 1 Examples of carboxylic acid esters with specific structures include ethyl acetate, butyl acetate, sec-butyl acetate, methoxybutyl acetate, amyl acetate, n-propyl acetate, isopropyl acetate, ethyl lactate, butyl lactate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, phenyl acetate, phenyl lactate, and phenyl propionate.

[0065] The sol of the present invention has a solid component of 0.1 to 60% by mass, or 1 to 55% by mass, or 10 to 55% by mass. Here, the solid component refers to the component after removing the solvent component from the total component of the sol.

[0066] The silica particles of the sol of the present invention are obtained by dynamic light scattering (DLS) method with an average particle size in the range of 5-200 nm or 5-150 nm, and the silica particles are obtained by transmission electron microscopy observation with an average primary particle size in the range of 5-200 nm, 5-150 nm or 5-100 nm.

[0067] The silica sol of the present invention is obtained through the following steps (A) to (B).

[0068] (A) Process: Obtaining silica particles with an average particle size of 5–200 nm obtained by dynamic light scattering as the dispersion medium, and using alcohol R 0 OH (where R) 0 This refers to an organic group that can have 1 to 10 carbon atoms and contain oxygen atoms. (The process involves using silica sol as a dispersion medium.)

[0069] (B) Process: Performing R to remove the silica sol obtained in (A) process. 0 Part of OH, all of it, and the addition of R 2 -COO-R1 Structure (where R) 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 The process of making carboxylic acid esters (representing alkyl groups with 1 to 10 carbon atoms).

[0070] Furthermore, the above manufacturing method can perform the following steps:

[0071] (A) The process involves obtaining silica particles with an average particle size of 5–200 nm obtained by dynamic light scattering as the dispersion medium, and using alcohol R… 0 OH (where R) 0 This refers to an organic group that can have 1 to 10 carbon atoms and contain oxygen atoms. (The process involves using silica sol as a dispersion medium.)

[0072] (B) Step is to remove the alcohol R from the silica sol obtained in step (A). 0 Part of OH, all of it, and the addition of R 2 -COO-R 1 Structure (where R) 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 R represents an alkyl group having 1 to 10 carbon atoms. 0 With R 1 The process of carboxylic acid esters (not the same chemical group).

[0073] Furthermore, the number of carbon atoms can also have R. 0 <R 1 The relationship.

[0074] (A) The silica sol in the process can be an alcohol R with 1 to 4 carbon atoms. 0 OH is used as the dispersion medium in silica sol. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, and propylene glycol monomethyl ether. Methanol is preferred among the above alcohols.

[0075] Alcohols with 1 to 4 carbon atoms R 0Silica sol using OH as the dispersion medium is obtained from aqueous silica sol as the starting material. Aqueous silica sol uses water glass as the starting material and consists of a step of a) obtaining active silicic acid by cation exchange of water glass, and b) obtaining silica particles by heating the active silicic acid. In step a), inorganic acids (e.g., hydrochloric acid, nitric acid, or sulfuric acid) are added to the active silicic acid to increase its purity, removing metal impurities and unwanted anions through cation and anion exchange to dissolve metal impurities other than silica. In step b), an alkaline component (e.g., NaOH, KOH) is added to the active silicic acid to grow silica particles. To promote silica particle growth, a seed solution and a feed solution containing an alkali are prepared from the active silicic acid obtained in step a). The seed solution is heated while the feed solution is supplied to increase the silica particle size, thereby obtaining an aqueous silica sol with arbitrary particle sizes.

[0076] Further preferably, acidic silica sol from the alkaline components added in step b) with the alkaline ions outside the particles removed is suitable as the starting material of the present invention.

[0077] In step (A) of the present invention, an alcohol R in which the aqueous medium solvent of the aqueous silica sol is replaced with an alcohol having 1 to 4 carbon atoms can be obtained. 0 OH (where R) 0 This refers to an alkyl group having 1 to 4 carbon atoms. The alcohol (especially methanol) is used as the dispersion medium in a silica sol, with silica particles of an average particle size of 5 to 200 nm obtained by dynamic light scattering as the dispersion medium and an alcohol having 1 to 4 carbon atoms as the dispersion medium.

[0078] Step (B) involves removing alcohols R with carbon numbers 1 to 4 from the silica sol obtained in step (A). 0 OH (where R) 0 Indicates an alkyl group having 1 to 4 carbon atoms. This alcohol (especially methanol) is a part to all of its components, and those with added R... 2 -COO-R 1 Structure (where R) 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 The process of making carboxylic acid esters (representing alkyl groups with 1 to 10 carbon atoms).

[0079] The above R 0 Partial to complete removal of OH (especially methanol), and the presence of R 2 -COO-R 1 The addition of carboxylic acid esters to the structure is also a so-called solvent substitution, but it is not necessary to completely replace R. 0OH removal enables R to be removed in subsequent processes. 0 Even after removing OH, some R can still remain. 0 OH. R 0 Removal of OH and having R 2 -COO-R 1 The addition of the carboxylic acid ester can be performed simultaneously or either one can be performed first.

[0080] The above solvent replacement can be carried out by evaporation or ultrafiltration. For example, the solvent obtained in step (A) can be replaced by evaporation or ultrafiltration in a temperature bath of 50–100°C. 0 A silica sol with OH as the dispersion medium is added to a flask, and a carboxylic acid ester is added to perform solvent displacement when the liquid temperature in the flask is 40–90°C. Solvent displacement can be carried out under normal or reduced pressure. Under reduced pressure, for example, a pressure of 50–600 Torr can be used. The solvent displacement can take approximately 0.1–10 hours.

[0081] In this invention, the following (A-1) process can be performed from the end of process (A) to the end of process (B):

[0082] (A-1) Step: A step of treating the silica sol obtained in step (A) with a hydrolysate of at least one silane compound selected from formulas (1) to (3) above.

[0083] In equation (1), R 3 R is an organic group consisting of alkyl, haloalkyl, alkenyl, aryl, or having an epoxy, (meth)acryloyl, mercapto, amino, urea, or cyano group, and is bonded to silicon atoms via a Si-C bond. 4 These represent alkoxy, acyloxy, or halogen groups, respectively, with 'a' representing an integer from 1 to 3.

[0084] In equations (2) and (3), R 5 and R 7 They are alkyl groups with 1 to 3 carbon atoms or aryl groups with 6 to 30 carbon atoms, and are bonded to silicon atoms through Si-C bonds. 6 and R 8 They represent alkoxy, acyloxy, or halogen groups respectively; Y represents alkylene, NH group, or oxygen atom; b is an integer from 1 to 3; c is an integer 0 or 1; and d is an integer from 1 to 3.

[0085] The aforementioned alkyl groups are alkyl groups having 1 to 18 carbon atoms, and examples include methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, 1-methyl-cyclopropyl, 2-methyl-cyclopropyl, n-pentyl, 1-methyl-n-butyl, 2-methyl-n-butyl, 3-methyl-n-butyl, 1,1-dimethyl-n-propyl, 1,2-dimethyl-n-propyl, 2,2-dimethyl-n-propyl, 1-ethyl-n-propyl, cyclopentyl, 1-methyl-cyclobutyl, 2-methyl-cyclobutyl, 3-methyl-cyclobutyl, 1 2-Dimethyl-cyclopropyl, 2,3-Dimethyl-cyclopropyl, 1-Ethyl-cyclopropyl, 2-Ethyl-cyclopropyl, n-Hexyl, 1-Methyl-n-pentyl, 2-Methyl-n-pentyl, 3-Methyl-n-pentyl, 4-Methyl-n-pentyl, 1,1-Dimethyl-n-butyl, 1,2-Dimethyl-n-butyl, 1,3-Dimethyl-n-butyl, 2,2-Dimethyl-n-butyl, 2,3-Dimethyl-n-butyl, 3,3-Dimethyl-n-butyl, 1-Ethyl-n-butyl, 2-Ethyl-n-butyl, 1,1,2-Trimethyl-n-propyl, 1 2,2-Trimethyl-n-propyl, 1-Ethyl-1-methyl-n-propyl, 1-Ethyl-2-methyl-n-propyl, Cyclohexyl, 1-Methyl-cyclopentyl, 2-Methyl-cyclopentyl, 3-Methyl-cyclopentyl, 1-Ethyl-cyclobutyl, 2-Ethyl-cyclobutyl, 3-Ethyl-cyclobutyl, 1,2-Dimethyl-cyclobutyl, 1,3-Dimethyl-cyclobutyl, 2,2-Dimethyl-cyclobutyl, 2,3-Dimethyl-cyclobutyl, 2,4-Dimethyl-cyclobutyl, 3,3-Dimethyl-cyclobutyl, 1-n-propyl-cyclopropyl, 2-n-propyl -Cyclopropyl, 1-Isopropyl-cyclopropyl, 2-Isopropyl-cyclopropyl, 1,2,2-Trimethyl-cyclopropyl, 1,2,3-Trimethyl-cyclopropyl, 2,2,3-Trimethyl-cyclopropyl, 1-Ethyl-2-methyl-cyclopropyl, 2-Ethyl-1-methyl-cyclopropyl, 2-Ethyl-2-methyl-cyclopropyl and 2-Ethyl-3-methyl-cyclopropyl, Hexyl, Heptyl, Octyl, Nonyl, Decyl, Undecyl, Dodecyl, Tridecyl, Tetradecyl, Pentadecyl, Hexadecyl, Heptadecanyl, Octadecanyl, etc., but not limited to these.

[0086] In addition, alkylene derivatives derived from the aforementioned alkyl groups can be cited as examples.

[0087] The aryl groups mentioned above are aryl groups with 6 to 30 carbon atoms, such as phenyl, naphthyl, anthracene, pyrene, etc.

[0088] As an alkenyl group, it is an alkenyl group with 2 to 10 carbon atoms, examples of which include vinyl, 1-propenyl, 2-propenyl, 1-methyl-1-vinyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, 1-ethylvinyl, 1-methyl-1-propenyl, 1-methyl-2-propenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-n-propylvinyl, 1-methyl-1-butenyl, 1-methyl-2-butenyl, 1-methyl-3-butenyl, 2-ethyl-2-propenyl, 2-methyl-1-butenyl, 2-methyl-2-butenyl, 2-methyl-3-propenyl -Butenyl, 3-methyl-1-butenyl, 3-methyl-2-butenyl, 3-methyl-3-butenyl, 1,1-dimethyl-2-propenyl, 1-isopropylvinyl, 1,2-dimethyl-1-propenyl, 1,2-dimethyl-2-propenyl, 1-cyclopentenyl, 2-cyclopentenyl, 3-cyclopentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, 1-methyl-1-pentenyl, 1-methyl-2-pentenyl, 1-methyl-3-pentenyl, 1-methyl-4-pentenyl, 1-n-butylvinyl, 2-methyl-1-pentenyl, 2-methyl-2-pentenyl, etc., but not limited to these.

[0089] Examples of alkoxy groups include those with 1 to 10 carbon atoms, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, 1-methyl-n-butoxy, 2-methyl-n-butoxy, 3-methyl-n-butoxy, 1,1-dimethyl-n-propoxy, 1,2-dimethyl-n-propoxy, 2,2-dimethyl-n-propoxy, 1-ethyl-n-propoxy, n-hexyloxy, etc., but are not limited to these.

[0090] Examples of acyloxy groups with 2 to 10 carbon atoms include methyl carbonyloxy, ethyl carbonyloxy, n-propyl carbonyloxy, isopropyl carbonyloxy, n-butyl carbonyloxy, isobutyl carbonyloxy, sec-butyl carbonyloxy, tert-butyl carbonyloxy, n-pentyl carbonyloxy, 1-methyl-n-butyl carbonyloxy, 2-methyl-n-butyl carbonyloxy, 3-methyl-n-butyl carbonyloxy, 1,1-dimethyl-n-propyl carbonyloxy, 1,2-dimethyl-n-propyl carbonyloxy, 2,2-dimethyl-n-propyl carbonyloxy, 1-ethyl-n-propyl carbonyloxy, n-hexyl carbonyloxy, 1-methyl-n-pentyl carbonyloxy, 2-methyl-n-pentyl carbonyloxy, etc., but are not limited to these.

[0091] Examples of halogen groups include fluorine, chlorine, bromine, and iodine.

[0092] Examples of organic groups with epoxy groups include 2-(3,4-epoxycyclohexyl)ethyl and 3-epoxypropoxypropyl.

[0093] The term "(meth)acryloyl" as used above refers to both acryloyl and methacryloyl groups. Examples of organic groups containing a (meth)acryloyl group include 3-methacryloyloxypropyl and 3-acryloyloxypropyl.

[0094] Examples of organic groups containing a thiol group include, for example, 3-mercaptopropyl.

[0095] Examples of organic groups containing amino groups include 2-aminoethyl, 3-aminopropyl, N-2-(aminoethyl)-3-aminopropyl, N-(1,3-dimethyl-butylene)aminopropyl, N-phenyl-3-aminopropyl, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyl, etc.

[0096] Examples of organic groups containing a urea group include, for example, 3-ureopropyl.

[0097] Examples of organogroups containing a cyano group include, for example, 3-cyanopropyl.

[0098] Formulas (2) and (3) above are preferably compounds in which trimethylsilyl groups can be formed on or near the surface of silica particles.

[0099] Examples of these compounds are shown below.

[0100]

[0101] In the above formula, R 12 It is an alkoxy group, for example, methoxy and ethoxy.

[0102] This is a process in which the hydroxyl groups on the surface of silica particles, or, for example, silanol groups in the case of silica particles, react with the aforementioned silane compound to treat the surface of the silica particles through siloxane bonds. The reaction temperature can be carried out in the range of 20°C to the boiling point of the dispersion medium, for example, in the range of 20°C to 100°C. The reaction time can be approximately 0.1 to 6 hours.

[0103] Preferred functional groups include trimethylsilyl, monomethylsilyl, dimethylsilyl, methacryloyloxypropylsilyl, and phenyl. Corresponding silane compounds include hexamethyldisilazane, hexamethylsiloxane, hexamethyldisilazane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, methacryloyloxypropyltrimethoxysilane, methacryloyloxypropyltriethoxysilane, acryloyloxypropyltrimethoxysilane, acryloyloxypropyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane.

[0104] The aforementioned silane compound can be used as a surface treatment for silica particles with a silicon atom density equivalent to 0.1 atoms / nm. 2 ~6.0 units / nm 2 A certain amount of silane compound is added to the silica sol to treat the surface of the silica particles.

[0105] Water is required in the hydrolysis of the above-mentioned silane compounds, but if the sol is a water-based solvent, then these water-based solvents are used; if the alcohol R has 1 to 4 carbon atoms... 0 For sols containing OH solvents, the water remaining in the alcohol solvent after the aqueous medium solvent is replaced with an alcohol solvent can be used. The remaining water is the water remaining after the aqueous medium sol solvent is replaced with an alcohol solvent having 1 to 4 carbon atoms; for example, water present in the aforementioned alcohol at a concentration of 1% or less, such as 0.01% to 1% by mass. Furthermore, hydrolysis can be carried out using a catalyst or under conditions without a catalyst.

[0106] In the absence of a catalyst, when the silica particles are present on the acidic side, a methanol silica sol with a pH of 2–6 (measured at a 1:1 ratio containing methanol and water) can be used.

[0107] When using a catalyst, examples of hydrolysis catalysts include metal chelates, organic acids, inorganic acids, organic bases, and inorganic bases. Examples of metal chelates used as hydrolysis catalysts include triethoxy-mono(acetylacetone)titanium and triethoxy-mono(acetylacetone)zirconium. Examples of organic acids used as hydrolysis catalysts include acetic acid and oxalic acid. Examples of inorganic acids used as hydrolysis catalysts include hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, and phosphoric acid. Examples of organic bases used as hydrolysis catalysts include pyridine, pyrrole, piperazine, and quaternary ammonium salts. Examples of inorganic bases used as hydrolysis catalysts include ammonia, sodium hydroxide, and potassium hydroxide.

[0108] In this invention, after step (A-1) is completed, step (A-2) may be included:

[0109] (A-2) Step: A step of adding a secondary or tertiary amine with a total carbon number of 5 to 35 to the silica sol obtained in step (A-1).

[0110] The content of the amine can be set to 0.01 to 10.0 mmol or 0.01 to 5.0 mmol relative to 100g of SiO2 particles.

[0111] Furthermore, the amount of amine added is preferably such that the pH of the silica sol is 4.0 to 9.5, and more preferably such that it is 4.0 to 7.5. The amount of amine added is determined as the content in the silica sol. The pH of the ester-dispersed silica sol of the present invention was measured against a liquid obtained by mixing silica sol with methanol and pure water in a mass ratio of 1:1:1 or 1:2:1.

[0112] Examples of secondary amines mentioned above include ethyl n-propylamine, ethyl isopropylamine, dipropylamine, diisopropylamine, ethyl butylamine, n-propyl butylamine, dibutylamine, ethyl pentylamine, n-propyl pentylamine, isopropyl pentylamine, dipentylamine, ethyl octylamine, isopropyl octylamine, butyl octylamine, and dioctylamine.

[0113] Examples of the aforementioned tertiary amines include triethylamine, ethyl di-n-propylamine, diethyl di-n-propylamine, tri-n-propylamine, triisopropylamine, ethyl dibutylamine, diethylbutylamine, isopropyl dibutylamine, diisopropyl ethylamine, diisopropyl butylamine, tributylamine, ethyl dipentylamine, diethylpentylamine, tripentylamine, methyl dioctylamine, dimethyl octylamine, ethyl dioctylamine, diethyl octylamine, trioctylamine, benzyl dibutylamine, and diazabicycloundecene.

[0114] Among the above-mentioned amines, secondary and tertiary amines having alkyl groups having a total number of carbon atoms of 6 to 35 are preferred, such as diisopropylamine, tripentylamine, triisopropylamine, dimethyloctylamine, and trioctylamine.

[0115] In this invention, since the silica sol uses a carboxylic acid ester as the dispersion medium, the silica particles preferably have irreversible hydrophobic groups on their surface. Therefore, it is preferable to treat them with a hydrolysate of at least one silane compound represented by formulas (1) to (3). These silane treatments are performed on the acidic side.

[0116] Furthermore, taking the example of replacing the methanol solvent sol with a carboxylic acid ester sol as an example, some of the silanol groups on the surface of the silica particles change to methoxy groups in the methanol solvent. By replacing the methanol solvent with a carboxylic acid ester, the methyl group of the methoxy group changes to an alkoxy group through an ester exchange reaction with the alkyl group adjacent to the ester bond of the carboxylic acid ester. The increase in the number of alkoxy groups reduces interparticle repulsion and increases the tendency for aggregation. This reaction is promoted on the acidic side and is stopped by the addition of the aforementioned amine, resulting in a (Si-OR) sol. 1 ) / (Si-OR 0 The molar ratio of (Si-OR) is 0.002 to 50, especially (Si-OR) 1 It contains silica particles with a molar ratio of 0.002 to 50 of (Si-OCH3).

[0117] Furthermore, if we take the example of replacing the solvent in a methanol solvate with a propylene glycol monomethyl ether acetate solvate, then in the methanol solvate, silanol groups and methoxy groups are present on the surface of the silica particles. By replacing the solvent with propylene glycol monomethyl ether acetate, 1-methoxy-2-propoxy groups are present through transesterification, but due to the acidity of the silanol groups, some of the methoxy groups are restored to methanol. Methanol and propylene glycol monomethyl ether are thus mixed in the carboxylic acid ester solvent. The aforementioned amine is also needed to control the acidity of this silanol.

[0118] This invention relates to silica sol dispersed in carboxylic acid esters, which can be used in applications such as adhesives, release agents, semiconductor sealing materials, LED sealing materials, coatings, in-film additives, hard coatings, photoresist materials, printing inks, detergents, cleaning agents, additives for various resins, insulating compositions, rust inhibitors, lubricants, metalworking oils, film coating agents, and release agents.

[0119] Example

[0120] (Analytical methods for particle-bound alcohols)

[0121] Add 20 ml of n-hexane to 4 ml of the sample, centrifuge (2770 G), discard the supernatant, and separate the precipitate. Further add 2–4 ml of acetone to redissolve the precipitate, then add n-hexane again until agglomeration occurs. Separate the precipitate by centrifugation (2770 G), repeating this process twice. Dry the resulting precipitate under vacuum at 150 °C to obtain a dry powder.

[0122] 0.2 g of the powder obtained above was mixed with 10 mL of 0.05 N sodium hydroxide aqueous solution and left at room temperature for 1 day. If there was any undissolved matter, it was removed by filtration or centrifugation. The solution was then subjected to gas chromatography to determine the amount of alcohol bound to the surface.

[0123] (Example 1)

[0124] Methanol-dispersed silica sol (with an average primary particle size of 45 nm, silica concentration of 40.5% by mass, and moisture content of 1.5%, obtained by the BET method, manufactured by Nissan Chemical Co., Ltd.) was prepared.

[0125] Add 900g of the above methanol sol to a 2L round-bottom flask, and while stirring the sol with an electromagnetic stirrer, add 9.0g of hexamethyldisiloxane. Then maintain the liquid temperature at 60°C for 2 hours.

[0126] Then, while using a rotary evaporator to evaporate and distill the solvent at a pressure of 500 Torr and a bath temperature of 80°C, 360g of PGMEA (propylene glycol methyl ether acetate) was supplied to partially replace the dispersion medium of the sol with PGMEA. While stirring the sol with an electromagnetic stirrer, 9.0g of hexamethyldisiloxane was added, and the liquid temperature was maintained at 60°C for 2 hours.

[0127] Then, while using a rotary evaporator to evaporate and distill the solvent at a pressure of 400–100 Torr and a bath temperature of 80°C, PGMEA was supplied to replace the dispersion medium of the sol. The replaced sol was stirred with a magnetic stirrer while 1.42 g of tri-n-octylamine (1.1 mmol relative to 100 g of SiO2 particles) was added to obtain a PGMEA-dispersed silica sol (SiO2 30.1 wt%, viscosity (20°C) 4.9 mPa·s, water 0.2 wt%, methanol 0.2 wt%, average silica particle size of 87 nm obtained by dynamic light scattering, and trimethylsilyl group binding density of 1.1 particles / nm). 2 The amount of methoxy groups bound to silica particles is 0.4 per nm. 2 The binding amount of 1-methoxy-2-propoxy groups is 0.06 per nm. 2 (Si-OR) 1 ) / (Si-OR 0 The molar ratio of -OR is 0.15. 1 It represents 1-methoxy-2-propoxy, -OR 0 It represents the methoxy group.

[0128] The pH of the liquid obtained by mixing the silica sol with methanol and pure water in a mass ratio of 1:1:1 was measured using a pH meter, and the result was 4.8.

[0129] When the sol is added to a sealed glass container, its viscosity does not increase after being kept at room temperature or 50°C for 4 weeks.

[0130] (Example 2)

[0131] A methanol-dispersed silica sol in the form of chain-like particles was prepared (average primary particle size of 11 nm, silica concentration of 20.5% by mass, moisture content of 1.5%, manufactured by Nissan Chemical Co., Ltd.).

[0132] Add 1000g of the methanol sol to a 2L round-bottom flask, stir the sol with a magnetic stirrer while adding 10.0g of hexamethyldisiloxane, and then keep the liquid temperature at 60°C for 2 hours.

[0133] Then, while using a rotary evaporator to evaporate and distill the solvent at a pressure of 400 Torr and a bath temperature of 80°C, 450g of PGMEA (propylene glycol methyl ether acetate) was supplied to partially replace the dispersion medium of the sol with PGMEA. Then, while stirring the sol with a magnetic stirrer, 10.0g of hexamethyldisiloxane was added. The liquid temperature was then maintained at 60°C for 2 hours. After cooling, 0.62g of tri-n-pentylamine (1.3 mmol relative to 100g of SiO2 particles) was added while stirring.

[0134] Then, while using a rotary evaporator to evaporate and distill the solvent at a pressure of 400–80 Torr and a bath temperature of 80–90 °C, PGMEA was supplied to replace the dispersion medium of the sol, resulting in a PGMEA-dispersed silica sol (SiO2 18.2% by mass, viscosity (20 °C) 8.4 mPa·s, water 0.1% by mass, methanol 0.1% by mass). The average particle size of the silica particles obtained by dynamic light scattering was 39 nm, and the trimethylsilyl group binding amount of the silica particles was 1.4 particles / nm. 2 The binding amount of methoxy groups to silica particles is 0.35 per nm. 2 The binding amount of 1-methoxy-2-propoxy groups is 0.08 per nm. 2 (Si-OR) 1 ) / (Si-OR 0 The molar ratio of -OR is 0.23. 1 It represents 1-methoxy-2-propoxy, -OR 0 It represents the methoxy group.

[0135] Furthermore, the amine content is 1.49 mmol relative to 100g of SiO2 in the silica particles.

[0136] The pH of the liquid, which was a mixture of silica sol, methanol, and pure water in a mass ratio of 1:1:1, was measured using a pH meter and the result was 5.6.

[0137] When the sol is added to a sealed glass container, its viscosity does not increase after being kept at room temperature or 50°C for 4 weeks.

[0138] (Example 3)

[0139] A water-dispersed silica sol (obtained by the BET method, with an average primary particle size of 11 nm, pH 3, and silica concentration of 33% by mass, manufactured by Nissan Chemical Co., Ltd.) was prepared.

[0140] 1000g of the aforementioned silica sol was added to a 2L glass reactor equipped with a stirrer, condenser, thermometer, and two inlets. While maintaining the sol in the reactor at a boil, methanol vapor generated in another boiler was continuously blown into the silica sol, causing the liquid level to rise slowly while water was displaced by the methanol. Displacement was stopped when the volume of the distillate became 9L, yielding 1100g of methanol-dispersed silica sol. The obtained methanol-dispersed silica sol had a SiO2 concentration of 30.5% by mass, a water content of 1.6% by mass, and a viscosity of 2 mPa·s.

[0141] 1000g of the methanol sol was added to a 2L round-bottom flask. While stirring the sol with a magnetic stirrer, 150g of n-butanol and 77.5g of methyltrimethoxysilane (Shin-Etsu Chemical, trade name KBM-13) were added. The liquid temperature was then maintained at 60°C for 5 hours. Then, while using a rotary evaporator to evaporate and distill the solvent at a pressure of 500–80 Torr and a bath temperature of 80°C, n-butyl acetate was supplied to replace the dispersion medium of the sol with n-butyl acetate. Then, 0.06 g of tri-n-pentylamine (0.9 mmol relative to 100 g of SiO2 particles) was added, resulting in a transparent colloidal-colored n-butyl acetate-dispersed silica sol (SiO2 40.5 wt%, viscosity (20°C) 3.2 mPa·s, water 0.02 wt%, methanol 0.02 wt%, n-butanol 4 wt%). The average particle size of the silica particles obtained by dynamic light scattering, measured after dilution with n-butyl acetate, was 19 nm, and the binding amount of methoxy groups on the silica particles was 0.44 methoxy groups / nm. 2 The butyloxy group binding amount is 0.71 per nm. 2 (Si-OR) 1 ) / (Si-OR 0 The molar ratio of -OR is 1.61. 1 It represents butoxyl, -OR 0 It represents the methoxy group.

[0142] The pH of the liquid, which was a mixture of silica sol, methanol, and pure water in a mass ratio of 1:2:1, was measured using a pH meter and the result was 5.3.

[0143] When the sol was added to a sealed glass container and kept at 50°C for 4 weeks, there was no increase in viscosity.

[0144] (Example 4)

[0145] 750 g of methanol-dispersed silica sol, prepared in the same manner as in Example 3, was added to a 1 L flask. While stirring the sol with a magnetic stirrer, 63.2 g of n-butanol and 58.2 g of methyltrimethoxysilane (Shin-Etsu Chemical, trade name KBM-13) were added. After heating at 60°C for 5 hours, 17.0 g of dimethyldimethoxysilane (Shin-Etsu Chemical, trade name KBM-22) was added. After further heating at 63°C for 3 hours, 0.46 g of n-tripentylamine (0.9 mmol relative to 100 g of SiO2 particles) was added.

[0146] Then, while using a rotary evaporator to evaporate and distill the solvent at a reduced pressure of 500–80 Torr and a bath temperature of 80°C, n-butyl acetate was supplied to replace the dispersion medium of the sol with n-butyl acetate, resulting in a transparent colloidal-colored n-butyl acetate-dispersed silica sol (SiO2 44.0 wt%, viscosity (20°C) 3.6 mPa·s, water 0.02 wt%, methanol 0.2 wt%, n-butanol 4 wt%). The average particle size of the silica particles, determined by dynamic light scattering method after dilution with n-butyl acetate, was 16 nm, and the binding amount of methoxy groups on the silica particles was 0.43 per nm. 2 The butyloxy group binding amount is 0.27 per nm. 2 (Si-OR) 1 ) / (Si-OR 0 The molar ratio of -OR is 0.63. 1 It represents butoxyl, -OR 0 It represents the methoxy group.

[0147] Furthermore, the amine content is 0.61 mmol relative to 100g of SiO2 in the silica particles.

[0148] The pH of the liquid, which was a mixture of silica sol, methanol, and pure water in a mass ratio of 1:1:1, was measured using a pH meter and the result was 5.2.

[0149] When the sol was added to a sealed glass container and kept at 50°C for 4 weeks, there was no increase in viscosity.

[0150] (Example 5)

[0151] 800 g of methanol-dispersed silica sol, prepared in the same manner as in Example 3, was added to a 1 L flask. While stirring the sol with a magnetic stirrer, 31.5 g of methyltrimethoxysilane (Shin-Etsu Chemical, trade name KBM-13) was added. After heating at 50°C for 3 hours, 240 g of n-butyl acetate was added while distilling using a rotary evaporator at a pressure of 500 Torr, thus replacing part of the dispersion medium of the sol with butyl acetate. Next, 18.2 g of dimethyldimethoxysilane (Shin-Etsu Chemical, trade name KBM-22) was added while stirring the sol with a magnetic stirrer. After further heating at 63°C for 3 hours, 8.0 g of hexamethyldisiloxane was added, and the mixture was heated at 60°C for 2 hours. After cooling, 0.49 g of n-tripentylamine (0.9 mmol relative to 100 g of SiO2 particles) was added to the above reaction solution while stirring.

[0152] Then, while using a rotary evaporator to evaporate and distill the solvent at a reduced pressure of 450–80 Torr and a bath temperature of 80°C, n-butyl acetate was supplied to replace the dispersion medium of the sol with n-butyl acetate, resulting in a transparent colloidal-colored silica sol dispersed in n-butyl acetate (SiO2 43.5% by mass, viscosity (20°C) 4.9 mPa·s, water 0.02% by mass, methanol 0.4% by mass, n-butanol 1.5% by mass). The average particle size of the silica particles, determined by dynamic light scattering method after dilution with n-butyl acetate, was 19 nm, and the binding amount of methoxy groups on the silica particles was 0.27 per nm. 2 The binding amount of butoxy groups is 0.05 per nm. 2 (Si-OR) 1 ) / (Si-OR 0 The molar ratio of -OR is 0.19. 1 It represents butoxyl, -OR 0 It represents the methoxy group.

[0153] The pH of the liquid, which was a mixture of silica sol, methanol, and pure water in a mass ratio of 1:1:1, was measured using a pH meter and the result was 4.7.

[0154] When the sol was added to a sealed glass container and kept at 50°C for 4 weeks, there was no increase in viscosity.

[0155] (Example 6)

[0156] Methanol-dispersed silica sol (average primary particle size 80 nm, silica concentration 30% by mass, moisture 1.5%, manufactured by Nissan Chemical Co., Ltd.) was prepared.

[0157] 1000g of the methanol sol was added to a 2L eggplant-shaped flask and concentrated using a rotary evaporator at a pressure of 300 Torr and a bath temperature of 60°C until SiO2 reached 35% by mass. Ethyl acetate was then added to adjust the SiO2 to 30% by mass, thus obtaining a methanol / ethyl acetate mixed solvent sol.

[0158] Next, while stirring the mixed solvent sol with an electromagnetic stirrer, 20.0 g of hexamethyldisiloxane was added, and the liquid temperature was maintained at 60°C for 4 hours. After cooling, 0.3 g of n-tripentylamine (0.43 mmol relative to 100 g of SiO2 particles) was added to the above reaction solution while stirring.

[0159] Then, while using a rotary evaporator to evaporate and distill the solvent at a pressure of 500 Torr and a bath temperature of 80°C, ethyl acetate was supplied to replace the dispersion medium of the sol with ethyl acetate, resulting in an ethyl acetate-dispersed silica sol (SiO2 30.6 wt%, viscosity (20°C) 1.5 mPa·s, water 0.06 wt%, methanol 0.05 wt%, ethanol 0.02 wt%), with an average silica particle size of 121 nm obtained by dynamic light scattering and a methoxy group binding capacity of 0.34 methoxy groups / nm for silica particles. 2 The amount of ethoxy groups bound is 0.01 per nm. 2 (Si-OR) 1 ) / (Si-OR 0 The molar ratio of -OR is 0.029. 1 It represents ethoxylation, -OR 0 It represents the methoxy group.

[0160] The pH of the liquid, which was a mixture of silica sol, methanol, and pure water in a mass ratio of 1:1:1, was measured using a pH meter and the result was 4.5.

[0161] When the sol is added to a sealed glass container, its viscosity does not increase after being kept at room temperature or 50°C for 4 weeks.

[0162] (Example 7)

[0163] A water-dispersed silica sol (with an average primary particle size of 12 nm, pH 3, and silica concentration of 33.5% by mass, obtained by the BET method, manufactured by Nissan Chemical Co., Ltd.) was prepared.

[0164] 300g of the above silica sol was added to a 500ml eggplant-shaped flask, and ethanol was added while distillation was carried out at a pressure of 140 Torr and a bath temperature of 80℃ to obtain a sol with 30.4% by mass of SiO2 and 12.4% by mass of water.

[0165] While stirring the sol with an electromagnetic stirrer, 14.5 g of phenyltriethoxysilane (Shin-Etsu Chemical, trade name KBE-103) was added, and the liquid temperature was maintained at 67°C for 2 hours. Then, heating was interrupted and 0.32 g of diisopropylamine (3.2 mmol relative to 100 g of SiO2 particles) was added, and the liquid temperature was further heated at 67°C for 1 hour. Then, while using a rotary evaporator to evaporate and distill the solvent at a pressure of 140–65 Torr and a bath temperature of 85–95 °C, PGMEA was supplied to replace the dispersion medium of the sol, thereby obtaining a transparent colloidal PGMEA-dispersed silica sol (SiO2 30.5% by mass, viscosity (20 °C) 3.8 mPa·s, water 0.06% by mass, 1-methoxy-2-propanol 0.1% by mass). The average particle size of the silica particles, determined by dynamic light scattering method after dilution with PGMEA, was 23 nm, and the binding amount of ethoxy groups on the silica particles was 0.01 particles / nm. 2 The binding amount of 1-methoxy-2-propoxy groups is 0.34 per nm. 2 (Si-OR) 1 ) / (Si-OR 0 The molar ratio of -OR is 34. 1 It represents 1-methoxy-2-propoxy, -OR 0 It represents ethoxy.

[0166] The pH of the liquid, which was a mixture of silica sol, methanol, and pure water in a mass ratio of 1:1:1, was measured using a pH meter and the result was 6.1.

[0167] When the sol was added to a sealed glass container and kept at 50°C for 4 weeks, there was no increase in viscosity or particle size according to dynamic light scattering.

[0168] (Comparative Example 1)

[0169] Without the addition of tri-n-octylamine, PGMEA-dispersed silica sol (SiO2 30.5 wt%, viscosity (20°C) 6.1 mPa·s, water 0.2 wt%, methanol 0.2 wt%) was obtained by the same procedure as in Example 1. The average particle size of silica particles obtained by dynamic light scattering was 110 nm, and the amount of trimethylsilyl groups bound to the silica particles was 1.1 particles / nm. 2 The amount of methoxy groups bound to silica particles is 0.4 per nm. 2 The binding amount of 1-methoxy-2-propoxy groups is 0.06 per nm. 2 (Si-OR) 1 ) / (Si-OR 0The molar ratio of -OR is 0.15. 1 It represents 1-methoxy-2-propoxy, -OR 0 The symbol represents the methoxy group. The pH of the liquid, which was a mixture of silica sol, methanol, and pure water in a mass ratio of 1:1:1, was determined using a pH meter and the result was 3.6.

[0170] When the sol was added to a sealed glass container and kept at room temperature for 4 weeks, the viscosity was 11.5 mPa·s, and the average particle size of the silica particles obtained by the dynamic light scattering method was 115 nm.

[0171] (Comparative Example 2)

[0172] No amine was added after replacement with n-butyl acetate. Otherwise, the procedure was the same as in Example 2, yielding a transparent colloidal-colored n-butyl acetate-dispersed silica sol (SiO2 40.5 wt%, viscosity (20°C) 3.2 mPa·s, water 0.02 wt%, methanol 0.02 wt%, n-butanol 4 wt%), with a dynamic light scattering particle size of 20 nm as determined by dilution with n-butyl acetate, and an methoxy group binding capacity of 0.42 methoxy groups / nm for silica particles. 2 The binding amount of butoxy groups is 0.70 per nm. 2 (Si-OR) 1 ) / (Si-OR 0 The molar ratio of -OR is 1.67. 1 It represents butoxyl, -OR 0 The symbol represents the methoxy group. The pH of the liquid, which was a mixture of silica sol, methanol, and pure water in a mass ratio of 1:2:1, was determined using a pH meter and the result was 3.5.

[0173] When the sol was added to a sealed glass container and kept at 50°C for 4 weeks, the viscosity was 6.0 mPa·s, and the average particle size of the silica particles obtained by the dynamic light scattering method increased to 37 nm.

[0174] Industry availability

[0175] A silica sol using carboxylic acid esters as a dispersion medium and a method for manufacturing the same are provided. The organosilica sol can be subjected to silane treatment on the surface of silica particles, followed by the addition of amines to provide a silica sol with improved stability.

Claims

1. A silica sol containing Si-OR on or near silica particles treated with silane. 1 The silica particles, alkoxylated as shown, serve as a dispersion containing R 2 -COO-R 1 The solvent of the carboxylic acid ester structure is used as the dispersion medium, and it contains amines, Si-OR 1 In the middle, R 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 -COO-R 1 In the middle, R 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 This refers to an alkyl group that can have 1 to 10 carbon atoms and may contain oxygen atoms.

2. The silica sol according to claim 1, wherein the dispersed phase is Si-OR present on or near the surface of silane-treated silica particles. 0 and Si-OR 1 At least two alkoxy groups are shown, and in (Si-OR) 1 ) / (Si-OR 0 The molar ratio of this silicon dioxide particles in Si-OR is 0.002 to 50. 0 and Si-OR 1 In the middle, R 0 R represents an organic group that can have 1 to 10 carbon atoms and may contain oxygen atoms. 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 0 With R 1 They are not the same chemical bases.

3. The silica sol according to claim 1 or 2, wherein the average particle size of the silica particles obtained by dynamic light scattering method is 5-200 nm.

4. The silica sol according to claim 1 or 2, R 1 It can be ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 1-methoxy-2-propyl, 1-ethoxy-2-propyl, or phenyl.

5. The silica sol according to claim 1 or 2, R 2 It can be methyl, ethyl, or propyl.

6. The silica sol according to claim 1 or 2, wherein the silane treatment of the silica particles is carried out by a hydrolysate of at least one silane compound selected from formulas (1) to (3). In equation (1), R 3 They are alkyl, haloalkyl, alkenyl, aryl, or organic groups having an epoxy, (meth)acryloyl, mercapto, amino, urea, or cyano group, and are bonded to silicon atoms via Si-C bonds. 4 These represent alkoxy, acyloxy, or halogen groups, respectively, with 'a' representing an integer from 1 to 3. In equations (2) and (3), R 5 and R 7 They are alkyl groups with 1 to 3 carbon atoms or aryl groups with 6 to 30 carbon atoms, and are bonded to silicon atoms via Si-C bonds. 6 and R 8 They represent alkoxy, acyloxy, or halogen groups respectively; Y represents alkylene, NH group, or oxygen atom; b is an integer from 1 to 3; c is an integer 0 or 1; and d is an integer from 1 to 3.

7. The silica sol according to claim 1 or 2, wherein the amine is a secondary or tertiary amine with a total carbon number of 5 to 35.

8. The silica sol according to claim 7, wherein the pH of the liquid obtained by mixing the silica sol containing the amine with methanol and pure water in a mass ratio of 1:1:1 to 1:2:1 is 4.0 to 9.

5.

9. The method for manufacturing silica sol according to claim 6, comprising steps (A) to (B) below, and from the end of step (A) to the end of step (B), comprising step (A-1) below, and step (A-2) below after the end of step (A-1). (A) Process: Obtaining silica particles with an average particle size of 5–200 nm obtained by dynamic light scattering as the dispersion phase, and using alcohol R 0 The process of using OH as the dispersion medium for silica sol, R 0 In OH, R 0 This refers to an organic group that can have 1 to 10 carbon atoms and contain oxygen atoms. (B) Process: Performing R to remove the silica sol obtained in (A) process. 0 Part of OH, all of it, and the addition of R 2 -COO-R 1 The process of carboxylic acid ester structure, R 2 -COO-R 1 In the middle, R 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 Alkyl groups having 1 to 10 carbon atoms (A-1) Step: A step of treating the silica particles contained in the silica sol obtained in step (A) with at least one silane compound represented by formula (1) to (3). (A-2) Step: A step of adding a secondary or tertiary amine with a total carbon number of 5 to 35 to the silica sol obtained in step (A-1).

10. The method for manufacturing silica sol according to claim 9, wherein step (A) involves obtaining silica particles with an average particle size of 5-200 nm obtained by dynamic light scattering as the dispersion medium, and using alcohol R... 0 The process of using OH as the dispersion medium for silica sol, R 0 In OH, R 0 This refers to an organic group that can have 1 to 10 carbon atoms and contain oxygen atoms. Step (B) involves removing the alcohol R from the silica sol obtained in step (A). 0 Part of OH, all of it, and the addition of R 2 -COO-R 1 The process of carboxylic acid ester structure, R 2 -COO-R 1 In the middle, R 1 R represents an organic group that can have 2 to 10 carbon atoms and may contain oxygen atoms. 2 R represents an alkyl group having 1 to 10 carbon atoms. 0 With R 1 They are not the same chemical bases.

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