JP7475791B2 - Method for producing addition-curable silicone composition - Google Patents

Description

The present invention relates to a method for producing an addition-curable silicone composition.

The required properties for addition-curing silicones used as sealants and adhesives for electronic components are becoming more stringent every year. Silicones are inherently highly gas permeable, so sulfur-containing gases can permeate silicone and damage electronic components. Therefore, a technology is known in which metal powders (particularly copper powder and copper-plated powder) are filled into addition-curing silicone compositions, which then react self-sacrificially with the sulfur-containing gas to protect electronic components.

In addition, acidic gases such as nitrogen oxides and sulfur oxides also corrode electronic components. To solve this problem, a technology is known in which a basic filler is added to the silicone rubber composition in advance, and the reaction between these materials results in the function of protecting the internal electronic components.

In order to capture both sulfur-containing gases and acidic gases with one material, it is desirable to have a metal powder and a basic filler coexist. The surface of the metal powder (especially copper) is treated with a surface treatment agent to prevent the powder from agglomerating. This surface treatment agent generally uses a fatty acid. When a basic filler coexists with a metal powder treated with this fatty acid, a neutralization reaction occurs, and the fatty acid disappears from the surface of the metal powder. Metal powder in this state acts on the platinum catalyst, significantly reducing its catalytic function.
The following documents are cited as examples of prior art related to the present invention.

JP 2003-96301 A Japanese Patent Application Laid-Open No. 5-230373 JP 2004-83905 A JP 2011-201934 A

The present invention therefore aims to provide a method for producing a silicone composition that exhibits good curing properties after long-term storage, even when a metal powder treated with a fatty acid and a basic filler coexist.

As a result of extensive research to solve the above problems, the inventors discovered that by using a basic filler (calcium carbonate) or the like that has been treated with a fatty acid and that has been heat-treated in advance, hardenability after long-term storage can be ensured even in a composition that also contains metal powder, and thus completed the present invention.
That is, the present invention provides the following method for producing an addition-curable silicone composition.
[1]
(A) an organopolysiloxane having two or more alkenyl groups in one molecule;
(B) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in each molecule;
(C) a hydrosilylation reaction catalyst;
(D) at least one selected from a metal powder having a surface treated with a fatty acid and a metal-plated powder having a surface treated with a fatty acid;
(E) calcium carbonate powder whose surface has been treated with a fatty acid;
and (F) a substance containing one or more compounds selected from the group consisting of an acetylene alcohol compound and a compound in which the alcoholic hydroxyl group of said compound is modified with a silane or a siloxane,
A method for producing an addition-curable silicone composition, comprising: a step of mixing the component (A) and the component (E) and then heat-treating the mixture; and a step of mixing a heat-treated product obtained in the heat-treating step with the remaining components.
[2]
The method for producing an addition-curable silicone composition according to [1], wherein the component (D) is at least one selected from the group consisting of copper powder the surface of which has been treated with a fatty acid and copper-plated powder the surface of which has been treated with a fatty acid.
[3]
The method for producing an addition-curable silicone composition according to [1] or [2], wherein the addition-curable silicone composition further comprises (G) a reinforcing silica.
[4]
The method for producing an addition-curable silicone composition according to [3], wherein in the heat treatment step, in addition to the components (A) and (E), the component (G) is further mixed.

The addition-curable silicone composition produced by the manufacturing method of the present invention has good curability even after long-term storage, even when a metal powder treated with a fatty acid and a basic filler are present. Therefore, the manufacturing method of the present invention makes it possible to obtain a one-part addition-curable silicone composition that can be stored for long periods of time.

The present invention will now be described in more detail.
The present invention relates to a method for producing an addition-curable silicone composition by mixing the following components (A) to (F), and, if necessary, component (G) and other components.
First, each component of the composition will be described.

Component (A) is an organopolysiloxane having two or more alkenyl groups in one molecule. There are no particular limitations on the molecular structure of this organopolysiloxane, and it may have a linear, branched, cyclic, or three-dimensional network structure.

Examples of alkenyl groups include vinyl groups, allyl groups, butenyl groups, pentenyl groups, hexenyl groups, and heptenyl groups, with vinyl groups being particularly preferred. Furthermore, the alkenyl groups in the molecule may be bonded to either the silicon atoms at the ends of the molecular main chain or to silicon atoms in the middle of the molecular chain, or may be bonded to both.

Examples of organic groups bonded to silicon atoms other than alkenyl groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and halogenated alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl. Methyl and phenyl groups are particularly preferred.

Examples of such organopolysiloxanes of component (A) include dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with trimethylsiloxy groups, methylvinylpolysiloxanes capped at both molecular chain terminals with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers capped at both molecular chain terminals with trimethylsiloxy groups, dimethylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups, methylvinylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers capped at both molecular chain terminals with dimethylvinylsiloxy groups, and dimethylpolysiloxanes capped at both molecular chain terminals with trivinylsiloxy groups.
an _{organopolysiloxane copolymer comprising a siloxane unit represented by the formula: R13SiO0.5} ^{, a} _{siloxane unit represented by the formula: R12R2SiO0.5, a unit represented by the formula: R12SiO} ^{, and} _{a siloxane unit} represented by the formula: _SiO2 ;
an _{organopolysiloxane} copolymer comprising a siloxane unit represented by _the ^{formula R12R2SiO0.5} and a siloxane unit represented by the formula _SiO2 ;
an organopolysiloxane copolymer comprising ^a siloxane unit represented by the formula: ^R13SiO0.5 _{, a} siloxane unit represented by the formula: _R12R2SiO0.5 ^, and a siloxane unit represented by _the formula: _SiO2 ;
an organopolysiloxane copolymer comprising ^a siloxane unit represented by _the formula: ^R12R2SiO0.5 _, a siloxane unit represented by the formula: ^R12SiO _, and a siloxane unit represented by the formula: _SiO2 ;
Examples include organopolysiloxane copolymers consisting of siloxane units represented by ^{the formula R1R2SiO and siloxane} units represented by the formula ^R1SiO1.5 or siloxane units represented by the formula _{R2SiO1.5 ,} and mixtures consisting of two or more of these organopolysiloxanes. In the above formula, ^R1 is an organic group other than an alkenyl group, and ^R2 is an alkenyl group, and examples thereof include those given above.

From the viewpoints of the physical properties of the resulting cured product and the workability of the composition, the kinetic viscosity of component (A) at 25°C is preferably in the range of 100 to 500,000 ^mm2 /s, and particularly preferably in the range of 300 to 100,000 ^mm2 /s. In this specification, the kinetic viscosity is a value measured at 25°C using a Cannon-Fenske viscometer.

(B) Organohydrogenpolysiloxane Component (B) is an organohydrogenpolysiloxane having two or more, and preferably from 3 to 100, hydrogen atoms bonded to silicon atoms (i.e., Si—H groups) per molecule. There are no particular limitations on the molecular structure of this organohydrogenpolysiloxane, and it may have any of a linear, branched, cyclic, and three-dimensional network structure.

As such an organohydrogenpolysiloxane, for example, one represented by the following average composition formula (2) is preferred.
H _a R ³ _b SiO _(4-ab)/2 (2)
In formula (2), R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, and a and b are numbers satisfying 0<a<2, 0.8≦b≦2, and 0.8<a+b≦3, and preferably 0.05≦a≦1, 1.5≦b≦2, and 1.8≦a+b≦2.7.

Examples of the unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond for ^R3 include the same as those exemplified as the organic group bonded to a silicon atom other than an alkenyl group in component (A) above. Representative examples are those having 1 to 10 carbon atoms, particularly 1 to 7 carbon atoms, and preferably an alkyl group having 1 to 3 carbon atoms, such as a methyl group, a phenyl group, and a 3,3,3-trifluoropropyl group.

Examples of component (B) include siloxane oligomers such as 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyltetracyclosiloxane, and 1,3,5,7,8-pentamethylpentacyclosiloxane; methylhydrogenpolysiloxanes capped with trimethylsiloxy groups at both molecular chain terminals, dimethylsiloxane-methylhydrogensiloxane copolymers capped with trimethylsiloxy groups at both molecular chain terminals, methylhydrogenpolysiloxanes capped with silanol groups at both molecular chain terminals, dimethylsiloxane-methylhydrogensiloxane copolymers capped with silanol groups at both molecular chain terminals, dimethylpolysiloxanes capped with dimethylhydrogensiloxy groups at both molecular chain terminals, methylhydrogenpolysiloxanes capped with dimethylhydrogensiloxy groups at both molecular chain terminals, dimethylsiloxane-methylhydrogensiloxane copolymers capped with dimethylhydrogensiloxy groups at both molecular chain terminals, and the ^like ; Examples of such silicone resins include silicone resins which are composed of (H)SiO1 _/2 units and SiO4 _/2 units and may optionally contain ^R3SiO1 _{/2 units} , ^R32SiO2 _{/2 units} , ^R3 (H)SiO2/2 units, (H)SiO3 _/2 units or ^R3SiO3 _/2 units (wherein ^R3 is the same as defined above).

The amount of component (B) used is preferably an amount such that the number of Si—H groups derived from component (B) is 0.1 to 5.0, and more preferably 0.1 to 2.0, per alkenyl group derived from component (A).
In the composition of the present invention, the content of the components (A) and (B) is preferably from 40 to 95% by mass, more preferably from 45 to 90% by mass, and even more preferably from 50 to 85% by mass.

(C) Hydrosilylation reaction catalyst Component (C) is a catalyst for promoting the addition reaction between the alkenyl group derived from component (A) and the hydrosilyl group (Si-H group) derived from component (B), and any of the well-known catalysts for hydrosilylation reactions can be used. Specific examples of such catalysts include platinum group metals such as platinum (including platinum black), rhodium, and palladium; H ₂ PtCl _{4.nH 2} O, H ₂ PtCl _{6.nH 2} O, NaHPtCl _{6.nH 2} O, KaHPtCl _{6.nH 2} O, Na ₂ PtCl _{6.nH 2} O, K ₂ PtCl _{4.nH 2} O, PtCl _{4.nH 2} O, PtCl ₂ , Na ₂ HPtCl _{4.nH 2} and the like. Examples of suitable platinum complexes include platinum chloride, chloroplatinic acid and chloroplatinate salts such as chloroplatinic acid 100 (wherein n is an integer of 0 to 6, preferably 0 or 6); alcohol-modified chloroplatinic acid (see U.S. Pat. No. 3,220,972); complexes of chloroplatinic acid and olefins (see U.S. Pat. Nos. 3,159,601, 3,159,662 and 3,775,452); platinum black, palladium or other platinum group metals supported on aluminum oxide, silica, carbon or other carriers; rhodium-olefin complexes; chlorotris(triphenylphosphine)rhodium (Wilkinson's catalyst); and complexes of platinum chloride, chloroplatinic acid or chloroplatinate salts with vinyl group-containing siloxanes, particularly vinyl group-containing cyclic siloxanes.

When using these catalysts, if they are solid catalysts, they can be used in solid form, but in order to cure the composition of the present invention uniformly, it is preferable to use chloroplatinic acid, the above complexes, and the above compounds dissolved in a suitable solvent such as toluene or ethanol.

The amount of component (C) used may be a so-called catalytic amount, preferably 0.1 to 500 ppm, and more preferably 0.5 to 200 ppm, in terms of the mass of platinum group metal element relative to component (A).

(D) Metal Powder or Metal Plated Powder Surface-Treated with Fatty Acid Component (D) is a metal powder surface-treated with a fatty acid, a metal plated powder surface-treated with a fatty acid, or both.
Examples of metals include gold, silver, copper, iron, nickel, aluminum, tin, zinc, etc. Any metal may be used as long as it is sulfurized by a sulfur-containing gas to prevent or delay the sulfur-containing gas from reaching electric or electronic components, but copper is preferred in terms of metal stability and cost.
The metal-plated powder is prepared by plating a metal oxide powder such as silica or an organic resin powder with a metal such as one of the metal powders described above. The preferred metals for plating are gold, silver, and copper, with copper being particularly preferred.

The metal powder and metal plating powder used in the present invention are surface-treated with a fatty acid, and examples of the fatty acid include caprylic acid, undecylenic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, allaginic acid, lignoceric acid, cerotic acid, melissic acid, myristoleic acid, oleic acid, linoleic acid, and linolenic acid.

The method of surface treatment with fatty acid is not particularly limited, and a metal powder or metal plating powder surface-treated with fatty acid by a known method can be used as component (D). In addition, the shape of component (D) is not particularly limited, but dendritic shape is preferable. In consideration of the fluidity and reinforcing properties of the composition, the median diameter (D50) in the volume-based particle size distribution of component (D) is preferably 0.05 to 50 μm, more preferably 0.5 to 30 μm.

The amount of component (D) added is preferably 0.1 to 50 parts by mass, and more preferably 1 to 30 parts by mass, per 100 parts by mass of component (A).

(E) Calcium carbonate powder surface-treated with fatty acid Component (E) is a calcium carbonate powder having basicity, the surface of which has been treated with a fatty acid. Examples of the fatty acid used for the surface treatment include caprylic acid, undecylenic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, allaginic acid, lignoceric acid, cerotic acid, melissic acid, myristoleic acid, oleic acid, linoleic acid, and linolenic acid.

Considering the fluidity and reinforcing properties of the composition, the particle size of component (E) is preferably 0.05 to 50 μm, more preferably 0.5 to 30 μm, in terms of the median size (D50) in the volume-based particle size distribution.

Commercially available calcium carbonate powders can be used, such as MC Coat S-20 manufactured by Maruo Calcium Co., Ltd.

The amount of component (E) added is preferably 0.1 to 200 parts by mass, and more preferably 1 to 100 parts by mass, per 100 parts by mass of component (A).

(F) Acetylene Alcohol Compound or Derivative Thereof Component (F) is an acetylene alcohol compound or a compound in which the alcoholic hydroxyl group of such a compound has been modified with silane or siloxane, and acts as an addition reaction inhibitor in the addition-curable silicone composition.

The acetylene alcohol compound may be any compound in which an ethynyl group and a hydroxyl group are present in the same molecule, but it is preferable that the ethynyl group and the hydroxyl group are bonded to the same carbon atom. Specific examples of such compounds include compounds represented by the following structural formula:

（式中、ｐは０～５０の整数であり、ｑは１～５０、好ましくは３～５０の整数である。括弧が付されたシロキサン単位の配列順は任意であってよい。） A compound in which an alcoholic hydroxyl group of an acetylene alcohol compound is modified with a silane or siloxane is a compound in which the hydrogen atom of the hydroxyl group of the acetylene alcohol is substituted with a Si-O-C bond and bonded to a silane or siloxane moiety. Specific examples thereof include compounds represented by the following structural formula:

(In the formula, p is an integer of 0 to 50, and q is an integer of 1 to 50, preferably 3 to 50. The order of the bracketed siloxane units may be arbitrary.)

Component (F) may be used alone or in combination of two or more. The amount of component (F) to be used is preferably 0.0001 to 5 parts by mass, more preferably 0.001 to 3 parts by mass, and even more preferably 0.01 to 1 part by mass, per 100 parts by mass of component (A).

(G) Reinforcing Silica The composition may contain reinforcing silica to reinforce the mechanical strength. Examples of reinforcing silica include fumed silica, precipitated silica, calcined silica, quartz powder, and diatomaceous earth. In addition, finely powdered silica having a specific surface area of 50 m ² /g or more, particularly 50 to 500 m ² /g, as measured by the BET method, is preferred. Although such finely powdered silica may be used as is, it is preferred to use finely powdered silica treated with an organosilicon compound such as methylchlorosilanes, dimethylpolysiloxane, or hexamethyldisilazane in order to impart fluidity to the composition.

The (G) component may be used alone or in combination of two or more types. When using the (G) component, the blending amount is preferably 0.1 to 200 parts by mass, more preferably 1 to 100 parts by mass, per 100 parts by mass of the (A) component.

(H) Adhesion promoter If the cured product requires adhesion to metals or organic resins, an adhesion promoter may be blended in. Examples of the adhesion promoter include silane coupling agents and siloxanes having reactive groups such as epoxy groups, alkoxysilyl groups, and (meth)acrylic groups, and an adhesion promoter selected from silanes and siloxanes having at least one functional group selected from carbonyl groups such as epoxy groups, alkoxysilyl groups, and (meth)acrylic groups is preferred.

When an adhesion promoter is added, the amount added is preferably 0.5 parts by mass or more per 100 parts by mass of component (A), and taking into account rubber elasticity and adhesion, it is preferably 0.5 to 10 parts by mass.

In addition to the above-mentioned components, the composition may further contain reinforcing silicone resins; inorganic fillers other than component (G), such as calcium silicate, titanium dioxide, ferric oxide, and carbon black, within the scope of the present invention.

[Step 1: Heat treatment step]
The method for producing an addition-curable silicone composition of the present invention is characterized by comprising the step of mixing all or a part of (A) the organopolysiloxane having two or more alkenyl groups in one molecule with (E) the calcium carbonate powder having a surface treated with a fatty acid, and heat-treating the mixture at a temperature of preferably 50° C. or higher, more preferably 80° C. to 200° C., and even more preferably 100° C. to 180° C. In this heat-treatment step, the heat treatment is preferably performed under reduced pressure conditions.
If this heat treatment step is not carried out, the composition will have poor curability even after long-term storage.

In this heat treatment process, components other than the components (A) and (E) may be mixed as long as the combination does not cause a hydrosilylation reaction. For example, it is preferable to use the components (A), (E) and (G).

[Step 2: Mixing step]
Following the heat treatment step, the heat-treated product obtained in the heat treatment step is mixed uniformly with the remaining components to obtain an addition-curable silicone composition. The mixing method may be any method known in the art, and examples of the mixing device include a planetary mixer.
The addition-curable silicone composition obtained by the production method of the present invention may be, like ordinary addition-reaction-curable silicone compositions, divided into two liquids, which are mixed and cured at the time of use, to form a so-called two-liquid composition; however, from the standpoint of workability when using the composition, etc., it is preferable to form the composition as a one-liquid type.
When preparing a one-liquid addition-curable silicone composition, the mixture obtained after the heat treatment step is mixed with the remaining components, including the remainder of component (A) if only a portion of component (A) was added to the heat treatment step. The order in which the remaining components are added is not particularly important.
By using such a method, it is possible to obtain a one-part addition-curable silicone composition that exhibits good curability even after long-term storage. Furthermore, the addition-curable silicone composition obtained by the production method of the present invention can be used as a sealing material or adhesive for electronic components, and as a material that can protect electronic components even in environments exposed to sulfur-containing gases and acidic gases.

The addition-curable silicone composition obtained by the manufacturing method of the present invention can be cured in the same manner and under the same conditions as known curable silicone rubber compositions. For example, it can be sufficiently cured at room temperature, but it may be heated if necessary. When heating, it is usually preferable to cure at a heating temperature of 60 to 200°C, and particularly 80 to 170°C. The curing time varies depending on the curing temperature and molding method, but is usually about 1 minute to 24 hours.

The following examples and comparative examples will explain the present invention in more detail.

[Examples 1 to 3, Comparative Examples 1 to 4]
An addition-curable silicone composition was produced according to the following procedure using the components (A) to (F) in the amounts (parts by mass) shown in Table 1. Note that the D50 of component (D) is a value in the volume-based particle size distribution measured using a Microtrac MT3000 (manufactured by Nikkiso Co., Ltd.).
Of each composition, a portion (50 parts by mass) of component (A), component (E), and component (G) (if used) were mixed and subjected to a heat treatment step at 150° C. for 2 hours. The pressure during the heat treatment step was 0.08 MPa or less. After the mixture of components (A), (E), and (G) was returned to 25° C. and atmospheric pressure, the remaining components (A), (C), (F), (B), (H) (if used), and (D) were added in this order and mixed, followed by a degassing treatment under reduced pressure to obtain a composition.
[Comparative Example 5]
The same procedure as in Example 1 was repeated except that the heat treatment step in Example 1 was not performed. In other words, the remaining components (A), (C), (F), (B) and (D) were added in this order to a mixture of a portion (50 parts by mass) of the component (A), the component (E), and the component (G); the mixture was mixed, and then subjected to a degassing treatment under reduced pressure to obtain a composition.
[Comparative Example 6]
The same procedure as in Example 2 was followed except that the heat treatment step was not performed. In other words, the remaining components (A), (C), (F), (B), (H) and (D) were added in this order to a mixture of a portion (50 parts by mass) of the component (A), the component (E), and the component (G); the mixture was mixed, and then subjected to a degassing treatment under reduced pressure to obtain a composition.

Component (A):
(A-1) Dimethylsiloxane terminated at both molecular chain ends with dimethylvinylsiloxy groups (kinematic viscosity at 25°C: 10,000 mm ² /s)
(A-2) Polysiloxane resin consisting of Vi(Me) _{2SiO1 /2} units and SiO4 _/2 units (kinematic viscosity at 25°C: 5,000 ^mm2 /s, molar ratio of Vi(Me)2SiO1/ ₂ units to SiO4 _{/ 2} units: 0.8)

Component (B): an organohydrogenpolysiloxane represented by the following formula:

Component (C): Toluene solution of platinum-divinyltetramethyldisiloxane complex (elemental platinum content: 0.5% by mass)

Component (D):
(D-1) Copper powder (FCC-SP-99, dendritic electrolytic copper powder, fatty acid treatment, D50 (μm) <13, manufactured by Fukuda Metal Foil and Powder Co., Ltd.)
(D-2) Copper powder (D-1 (commercial product) not treated with fatty acid)

Component (E):
(E-1) Ground calcium carbonate whose surface has been treated with a fatty acid (MC Coat S-20, manufactured by Maruo Calcium Co., Ltd.)
(E-2) Calcium carbonate with untreated surface (Whiten SSB, manufactured by Shiraishi Calcium Co., Ltd.)

(F) Ingredient: Ethynylcyclohexanol

Component (G): Fumed silica surface-treated with hexamethyldisilazane (BET specific surface area: 300 ^m2 /g)

Component (H): a compound represented by the following structural formula:

[Evaluation of Curability]
Each composition was heated at 100°C using an Alpha Technology MDR2000 rheometer immediately after production and after storage at 5°C for 6 months. The time at which the torque reached 10% compared to the time at the end of heating was measured as T10, and the time at which the torque reached 90% was measured as T90. The curability of the composition was evaluated using the following index.
◯: T10 is 15 minutes or less and T90 is 30 minutes or less. △: T10 is 30 minutes or less and T90 is more than 30 minutes and less than 60 minutes, or T10 is more than 15 minutes and less than 30 minutes and T90 is 30 minutes or less. ×: Not cured, or T10 exceeds 30 minutes.

As shown in Table 1, the composition obtained by the production method of the present invention maintained its curability even after long-term storage.
On the other hand, in Comparative Examples 1 and 2, which used calcium carbonate whose surface was not treated with a fatty acid, the initial hardening property and the hardening property after long-term storage were poor, and in Comparative Examples 3 and 4, which used copper powder whose surface was not treated with a fatty acid, and in Comparative Examples 5 and 6, which did not undergo a heat treatment step of the mixture of component (A) and component (E), the hardening property after long-term storage was insufficient.

Claims (3)

(A) an organopolysiloxane having two or more alkenyl groups in one molecule;
(B) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in each molecule;
(C) a hydrosilylation reaction catalyst;
(D) at least one selected from copper powder having a surface treated with a fatty acid and copper-plated powder having a surface treated with a fatty acid;
(E) A calcium carbonate powder having a surface treated with a fatty acid, the surface of which has a median diameter (D50) in a volume-based particle size distribution of 0.5 to 30 μm.
and (F) a substance containing one or more compounds selected from the group consisting of an acetylene alcohol compound and a compound in which the alcoholic hydroxyl group of said compound is modified with a silane or a siloxane,
A method for producing an addition-curable silicone composition, comprising: a step of mixing the component (A) and the component (E) and then heat-treating the mixture at 80°C to 200°C; and a step of mixing the heat-treated product obtained in the heat-treating step with the remaining components. 2. The method for producing an addition-curable silicone composition according to claim 1 , wherein the addition-curable silicone composition further comprises (G) a reinforcing silica. 3. The method for producing an addition-curable silicone composition according to claim 2 , wherein in the heat treatment step, component (G) is further mixed in addition to components (A) and (E).