JP2007326726A - Silica powder, its manufacturing method and its use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide silica powder which has excellent light transmittance equal to that of an epoxy resin, the light transmittance of which is hardly deteriorated even when used for a long time and which is suitable for producing an LED sealing resin composition or the like and to provide a method for manufacturing the silica powder and a rubber or resin composition, particularly, the LED sealing resin composition using the silica powder. <P>SOLUTION: The silica powder has 120-250 m<SP>2</SP>/g specific surface area when measured according to a BET one-point method, ≤1.8 cc/100 g linseed oil absorption capacity per 1 m<SP>2</SP>specific surface area when measured according to JIS-K5101-13-1 and ≥0.85 average sphericity. The method for manufacturing the silica powder comprises the steps of: forming a high temperature field of ≥1,600°C; and jetting gaseous organosiloxane of 1/200 to 1/5 times of the volume of the high temperature field toward the high temperature field at 200-800 m/second jetting speed to heat-treat the jetted organosiloxane. A composition is obtained by mixing the obtained silica powder in at least one of the epoxy resin and a silicone resin. The LED sealing resin composition consists of the obtained composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to silica powder, a method for producing the same, and use thereof.

Conventionally, an epoxy resin has been used as an LED sealing resin. Epoxy resins are excellent in light transmittance, have good moldability, and are inexpensive, but are easily deteriorated by long-term use, and light transmittance is lowered. This problem is not so serious in LED display applications such as pilot lamps and electric bulletin boards, but cannot be ignored in lighting applications such as fluorescent lamp replacement, automotive headlights, and liquid crystal display backlights. . Moreover, the white LED generates more heat than the conventional LED, but it often happens that the wire breaks due to the large stress of the epoxy resin and the LED does not light up.

Therefore, it has been proposed to use a silicone resin in place of the epoxy resin, but the silicone resin is inferior in moldability and more expensive than the epoxy resin, so it is not a full replacement for the epoxy resin. Therefore, epoxy resins still have great attraction, and it has been proposed to fill various silica powders in order to improve their drawbacks. However, silicon tetrachloride flame pyrolysis silica powder (fumed silica) has a structure structure and thus becomes cloudy even when filled in small amounts. Hydrous silica silicate powder (sodium silicate silica) using sodium silicate as a raw material has purity. As low as 95%, it is colored by impurities and has a lot of agglomeration, so dispersion in the epoxy resin is not good. Metallic silica powder combustion method Silica powder has a BET specific surface area of 120 m ² / g at most, so it scatters light The silicone oil combustion method silica powder (Patent Document 1) formed agglomeration due to the structure, and in all cases reduced the light transmittance.
JP 2002-060214 A

An object of the present invention is a silica powder suitable for producing a resin composition for LED encapsulation having a good light transmittance equivalent to that of an epoxy resin, and a decrease thereof is small even when used for a long time, and a method for producing the silica powder Is to provide. Another object is to provide a rubber composition or a resin composition (hereinafter referred to as “composition” together) having improved light transmittance, particularly an epoxy resin composition or a silicone resin. It is providing the resin composition for LED sealing by which the light transmittance improved.

The present invention has a BET single point method specific surface area of 120 to 250 m ² / g, linseed oil absorption according to JIS-K5101-13-1 is 1.8 cc / 100 g or less per 1 m ^{2 of} specific surface area, and average sphericity is 0.85 or more. This is a silica powder. In the present invention, the BET one-point specific surface area is 160 to 220 m ² / g, the linseed oil absorption according to JIS-K5101-13-1 is 1.6 cc / 100 g or less per 1 m ^{2 of} specific surface area, and the average sphericity is 0.93. The above is preferable. Further, it is more preferable that the surface is treated with a surface active agent.

Further, the present invention is to heat-treat by injecting 1/200 to 1/5 times the amount of organosiloxane per second at a protruding speed of 200 to 800 m / sec. Is a method for producing silica powder. In this invention, it is preferable that the molecular weight of the organosiloxane is 1500 or less.

Furthermore, the present invention is a composition comprising the silica powder of the present invention contained in at least one of an epoxy resin and a silicone resin, particularly an LED sealing composition.

According to the present invention, there are provided a silica powder suitable for obtaining a resin composition having good light transmittance equivalent to that of an epoxy resin and having a small deterioration with time, and an easy production method thereof. Moreover, according to this invention, the composition with favorable light transmittance, especially the composition for LED sealing are provided.

In the present invention, if the BET single point method specific surface area of the silica powder is less than 120 m ² / g, the light transmittance of the composition deteriorates, and if it exceeds 250 m ² / g, the light transmittance of the composition decreases with time. A preferable BET one-point specific surface area is 160 to 220 m ² / g.

Further, when the linseed oil absorption amount of silica powder according to JIS-K5101-13-1 exceeds 1.8 cc / 100 g per 1 m ^{2 of the} specific surface area, the light transmittance of the composition decreases significantly with time, and the filling amount is to compensate for it. When the amount is increased, the viscosity of the composition increases and molding becomes difficult. The linseed oil absorption is preferably as small as possible, and particularly preferably 1.6 cc / 100 g or less per 1 m ^{2 of} specific surface area.

When the average sphericity of the silica powder is less than 0.85, it is difficult to mold the composition having a filling amount for developing good light transmittance. A preferable average sphericity is 0.93 or more.

The average sphericity is obtained by taking a particle image observed from a TEM photograph into an image analyzer (for example, manufactured by Nippon Avionics Co., Ltd.), and measuring the projected area (A) and perimeter length (PM) of the particle from the photograph. That is, when the area of a perfect circle corresponding to the perimeter (PM) is (B), the roundness of the particle is A / B. Assuming a perfect circle having the same circumference as the circumference of the particle (PM), PM = 2πr and B = πr ² , so B = π × (PM / 2π) ² , and the roundness of the particle is , Roundness = A / B = A × 4π / (PM) ² This is calculated | required about arbitrary particles 200, and let the average value be average sphericity.

The silica powder of this invention can be manufactured with the manufacturing method of the silica powder of this invention. In the present invention, the organosiloxane is injected as a gas into a high temperature field. Even if the organosiloxane is supplied in a liquid state, the BET one-point specific surface area of the silica powder does not exceed 120 m ² / g. Organosiloxane preferably has a molecular weight of 1500 or less in order to facilitate gasification. Examples of such organosiloxanes include linear dimethylpolysiloxane ((CH ₃ ) ₃ SiO [Si (CH ₃ ) ₂ O] _n Si (CH ₃ ) ₃ , where 1 ≦ n ≦ 18), hexamethyldi Siloxane, octamethyltrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and the like. Particularly preferred are those in which n is 1 to 3 in the above general formula and decamethylcyclopentasiloxane.

The organosiloxane gas is injected into a high temperature field at a temperature of 1600 ° C. or higher at a protruding speed of 200 to 800 m / sec. When the protrusion speed is less than 200 m / sec, the BET single point method specific surface area of the obtained silica powder does not exceed 120 m ² / g, and when it exceeds 800 m / sec, the temperature in the high temperature field decreases and unreacted. The amount of organosiloxane increases. A preferable protrusion speed is 300 to 600 m / sec. The organosiloxane gas is mixed with an auxiliary combustion gas such as air or oxygen, or a fuel gas such as LPG and injected from the nozzle. The protruding speed of the organosiloxane gas can be controlled by adjusting the nozzle diameter and the flow rate of the auxiliary gas or fuel gas. The organosiloxane gas concentration in the propellant gas is preferably 0.5 to 5% by volume from the viewpoint of suppressing the structure structure. The gasification of the organosiloxane is performed by heating and evaporation of the liquid organosiloxane.

The amount of the organosiloxane gas sprayed is 1/200 to 1/5 times the volume of a high temperature field volume of 1600 ° C. or higher. If the amount is less than 1/200, it is difficult to control the BET single point method specific surface area by adjusting the furnace temperature. If the amount exceeds 1/5, adhesion is formed and the sphericity is lowered. The amount is preferably 1/100 to 1/10 times the amount per second. The place to inject is a high temperature field where the temperature is 1600 ° C. or higher, particularly 1800 to 2200 ° C. When sprayed to a place below 1600 ° C., the amount of unreacted organosiloxane increases.

Patent Document 1 describes that silica powder is produced by burning silicone oil, and that the obtained silica powder has a BET one-point specific surface area of 3 to 300 m ² / g. However, Patent Document 1 discloses that an organosiloxane gas is injected, the injection amount is 1/200 to 1/5 times the volume of a high temperature field at a temperature of 1600 ° C. There is no description about the speed of 200 to 800 m / sec. Therefore, although the specific surface area of the silica powder manufactured by patent document 1 and the manufacturing method of this invention may become comparable, the linseed oil absorption amount of patent document 1 is 1. per 1 m < ² > of specific surface area of this invention. It becomes significantly larger than 8cc / 100g.

In the present invention, formation of a high temperature field having a temperature of 1600 ° C. or higher and production of silica powder using the high temperature field are performed, for example, as follows. As an apparatus, what consists of a furnace and the collection apparatus connected to this furnace is preferable, and the example is shown in Unexamined-Japanese-Patent No. 2001-335313. More specifically, the furnace may be either a vertical furnace or a horizontal furnace, but is preferably a vertical furnace. The furnace is composed of a melting zone for changing the organosiloxane gas into silica, melting the silica into a semi-molten state and making it spheroidized, and a cooling zone for cooling and solidifying the spheroidized particles. The melting zone is also a high temperature field having a temperature of 1600 ° C. or higher, and is formed by a flame. In the cooling zone, the spheroidized particles are cooled to a temperature at which the operation in the collecting device is easy. Cooling is performed by natural cooling or forced cooling. In natural cooling, the cooling zone is designed to be long enough for the spheroidized particles to stay for the time to reach that temperature. Forced cooling is performed by supplying a cooling gas such as air, for example, at any time from the cooling zone to the collecting device. In the collection device, for example, at least one collector such as a heavy sedimentation chamber, a cyclone, and a bag filter is installed. An organosiloxane gas injection port is attached to one of the furnaces, but in a vertical furnace, it is usually attached to the upper surface of the furnace. Preferably, an organosiloxane gas injection port is preferably provided at the center (circular center) of the fuel burner provided on the upper surface of the furnace in order to form a melting zone. For this, a two-fluid nozzle is suitable. One or a plurality of such burners are installed.

The flame can be formed by injecting a fuel gas such as propane gas, butane gas, hydrogen, and an auxiliary combustion gas such as oxygen or air from a fuel burner. In the present invention, auxiliary combustion gas can be individually injected from the outer peripheral portion of the flame.

The BET single point specific surface area of the silica powder can be controlled by the protruding speed of the organosiloxane gas and the injection amount. The specific surface area increases as the protrusion speed increases and the injection amount decreases. The amount of linseed oil absorption can be controlled by the temperature in the high temperature field and the amount of organosiloxane injected. The higher the temperature in the high temperature field and the smaller the amount of organosiloxane sprayed, the smaller the linseed oil absorption.

Examples of the epoxy resin used in the composition of the present invention include bisphenol A type epoxy resin, bisphenol F type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, Phenol novolac type epoxy resins, orthocresol novolac type epoxy resins, and the like. Examples of the silicone resin include methyl silicone resin, methylphenyl silicone resin, alkyd-modified silicone resin, epoxy-modified silicone resin, acrylic-modified silicone resin, and polyester-modified silicone resin. As for the content rate in the composition of a silica powder, 40-70 mass% is preferable.

The composition for LED sealing of this invention consists of a composition of this invention. LED sealing material is comprised from the composition of this invention, the hardening | curing agent of the composition, and a curing catalyst. Examples of curing agents include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyl nadic anhydride, nadic anhydride, glutaric anhydride, etc. is there. Examples of the curing catalyst include imidazoles, triphenylphosphine, tributylphosphine or salts thereof, DBU (diazabiscycloundecene), tertiary amine, carboxylic acid metal salts, and the like. If an example of a compounding example is shown, a hardening | curing agent will be 80-110 mass parts and a curing catalyst will be 0.01-10 mass parts per 100 mass parts of compositions of this invention. If necessary, a dye, a fluorescent agent, a modifier, a discoloration inhibitor, a release agent, and the like are blended. The form is often liquid, powder or tablet. The LED element is sealed with the LED sealing material by conventional means such as transfer molding and casting.

A burner (cylindrical shape with a diameter of 150 mm), the auxiliary combustion gas supply part of which is composed of a combustible gas supply part, is installed on the upper surface of a vertical furnace (diameter 700 mm × height 5000 mm) and placed at the center of the burner A two-fluid nozzle (trade name “BNH-160S” manufactured by Atmax Co., Ltd.) was inserted through the nozzle installation tube. Decamethylcyclopentasiloxane (molecular weight: 370) was heated to 350 ° C. as organosiloxane while supplying a combustible gas (LPG gas) of 6 Nm ³ and an auxiliary combustion gas (oxygen gas) of 18 Nm ³ per hour to form a flame. Nitrogen gas 10Nm ³ heated to 350 ° C. was gasified by an evaporator and injected from a two-fluid nozzle as carrier gas and oxygen 30Nm ³ as dispersion gas. Decamethylcyclopentasiloxane shows the gas in double the amount shown in Table 1 with respect to the volume in a high temperature field of 1600 ° C. or higher (the volume calculated from the image of thermography “TH9100MV” manufactured by NEC Sanei Co., Ltd.). Injected into a hot field at a protruding speed. The produced silica powder was sucked and transported from the lower part of the furnace to a collection system by a blower and collected by a bag filter. Silica powders A to M shown in Table 1 were produced by changing the injection amount of decamethylcyclopentasiloxane and the conditions of the protruding speed. In addition, silica powder B is prepared by adding 200 g of silica powder A to a vibrating fluidized bed (Chuo Kakoki Co., Ltd. “vibrating fluidized bed apparatus VUA-15 type”) and fluidizing it with air circulated by a suction blower. After 18 g is sprayed and fluidized and mixed for 5 minutes, 30 g of HMDS (trade name “TSL-8802” manufactured by Toshiba Silicone Co., Ltd.) is sprayed and fluidized and mixed for 30 minutes for surface treatment.

Examples 1-9 Comparative Examples 1-4
200 parts by mass of methyl ethyl ketone dispersion of silica powder as silica powder, 100 parts by mass of tetrahydrophthalic anhydride, 100 parts by mass of DBU (diazabiscycloundecene) per 100 parts by mass of bisphenol A type epoxy resin having an epoxy equivalent of 185 The fluidity of the composition obtained by mixing parts by mass was measured. Thereafter, the composition is dried to remove methyl ethyl ketone, and then cured by heating with a mold to produce a cured epoxy resin (width 10 mm, length 100 mm, thickness 4 mm). Changes were measured. The results are shown in Table 1. In Comparative Examples 1 and 4, when the proportion of the silica powder was 200 parts by mass, the fluidity deteriorated and it was difficult to mold, so the proportion of the silica powder was 150 parts by mass.

(1) Fluidity of the composition 90 parts by mass of a bisphenol A type epoxy resin having an epoxy equivalent of 185 and 10 parts by mass of silica powder were revolved using a self-revolving kneading machine (Shinky Co., Ltd .: Awatori Kentaro). The mixture was mixed for 10 minutes at 2000 rpm and 600 rpm, and the viscosity at 1 rpm was measured with an E-type viscometer (manufactured by Toki Sangyo Co., Ltd .: TVE-30H).
(2) Light transmittance and its change with time The initial light transmittance of the cured epoxy resin was measured at a wavelength of 600 nm using an ultraviolet-visible near-infrared spectrophotometer ("V-530 type" manufactured by JASCO). Thereafter, the light transmittance over time was measured after the epoxy resin cured body was irradiated with ultraviolet rays for 1 week using an ultra-high pressure mercury lamp (ML-501C / B, manufactured by Ushio Inc., main wavelength 365 nm). Good light transmittance is 80% or more.

The silica powder of the present invention can be used as a filler for a composition, a raw material for producing a silica sintered body, and the like. Moreover, the composition of this invention can be used for the composition for LED sealing, and the manufacturing raw material of various moldings.

Claims (7)

Silica powder having a BET one-point specific surface area of 120 to 250 m ² / g, linseed oil absorption according to JIS-K5101-13-1 of 1.8 cc / 100 g or less per 1 m ^{2 of} specific surface area, and an average sphericity of 0.85 or more . The BET single point method specific surface area is 160 to 220 m ² / g, the linseed oil absorption according to JIS-K5101-13-1 is 1.6 cc / 100 g or less per 1 m ^{2 of} specific surface area, and the average sphericity is 0.93 or more. The silica powder according to 1. The silica powder according to claim 1 or 2, which has been treated with a surfactant. It is characterized in that heat treatment is carried out by injecting an organosiloxane gas in an amount of 1/200 to 1/5 times the volume of a high temperature field at a temperature of 1600 ° C. or more to a high temperature field at a protruding speed of 200 to 800 m / sec. A method for producing silica powder. The production method according to claim 4, wherein the molecular weight of the organosiloxane is 1500 or less. A composition comprising the silica powder according to claim 1 or 2 in at least one of an epoxy resin and a silicone resin. The composition for LED sealing which consists of a composition of Claim 6.