JP5230457B2 - Storage method of hydrophilic dry silica - Google Patents

Description

  The present invention relates to a method for preserving hydrophilic dry silica that is suitably used as a filler for a resin composition used for a semiconductor encapsulant, a semiconductor mounting adhesive, and the like.

In recent years, with the downsizing and thinning of semiconductor devices, the particle diameter of fillers added to semiconductor sealing resins and semiconductor mounting adhesives, which are epoxy resin compositions, tends to become smaller, and the BET ratio Hydrophilic dry silica having a surface area of 20 to 55 m ² / g may be used (see Patent Document 1).

  Usually, since the silica manufacturer and the resin composition manufacturer are different, the manufactured silica is subdivided into various packaging forms and stored after manufacture, and the required amount is shipped according to the order of the resin composition manufacturer. Often done. This shelf life ranges from a few days to several years.

JP 2008-19157 A

However, in the above-mentioned hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g, the longer the storage period of the silica, the higher the viscosity of the resin composition added as a filler. When the preserved silica is used, there is a problem that it becomes difficult to seal, mold and mount the semiconductor.

Accordingly, an object of the present invention is to provide a method for preserving hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g, which suppresses an increase in viscosity when added to a resin even when the storage period is long. is there.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that, in hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g, moisture adsorbed on the surface of the silica during the storage period. However, it was found that the aggregation of the silica particles was promoted and strengthened, and the aggregation increased the viscosity of the resin composition. Thus, the present inventors have found that the increase in the viscosity of the resin composition when using the silica can be suppressed by storing the silica so that the moisture content of the silica from the production to the use is maintained below a certain value, and the present invention is completed. It came to.

That is, the storage method of the present invention is a storage method for hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g, and is represented by the following formula (1):
w ≦ 0.01 × S (1)
(W is the water content (wt%) of hydrophilic dry silica measured by the loss on drying method at 130 ° C., and S is the BET specific surface area (m ² / g) of hydrophilic dry silica. .)
The hydrophilic dry silica produced so as to satisfy the above condition is stored until it is used while maintaining the condition satisfying the above formula (1).

In addition to the above formula (1), the following formula (2)
τ ≦ 240S ^−1.4 −0.07 (2)
(In the above formula, τ is the absorbance with respect to light having a wavelength of 700 m of an aqueous suspension containing hydrophilic dry silica at a concentration of 1.5 wt%, and S is the BET specific surface area (m ² / g of hydrophilic dry silica). ).)
It is particularly preferable that the hydrophilic dry silica produced so as to satisfy the above conditions is stored until use while maintaining the state satisfying both the above formulas (1) and (2).

If the storage method of the present invention is applied, the hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g is added to the resin to produce a resin composition without worrying about the storage period of the silica. A resin composition having excellent viscosity characteristics can be obtained.

  In the present invention, dry silica refers to silica produced and / or melted in the gas phase, or silica surface-treated after being produced and / or melted in the gas phase.

  More specifically, silicon halides such as monochlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethyldisiloxane, octamethyltrimethyl. From a burner a mixed gas of a silicon-containing compound such as siloxane such as siloxane and a combustion-supporting gas such as oxygen (a dilution gas such as nitrogen or an auxiliary combustion gas such as hydrogen may be used if necessary) Silica produced by a method of burning while being blown; Silica produced by a method of heat-treating metal silicon powder in a high-temperature and oxidizing atmosphere such as in a flame; Melting crushed quartz and silica aggregates in a flame Silica, etc. produced by re-solidification after Silica or the like to these surface-treated with various silane coupling agents and the like.

  In addition, since such dry silica undergoes extremely high temperatures due to the combustion of silicon-containing compounds and the melting of silica in the production process, the adhering moisture is produced by a wet method (sodium silicate neutralization or sol-gel method). The amount of silica is much smaller than that of the formed silica.

  In the present invention, the silica is hydrophilic when silica is stirred and mixed in water so that the silica concentration is 1.5% by weight. The case where it is mixed.

  As such hydrophilic silica, those having no surface treatment, mainly γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, Silane coupling agents having an epoxy functional group such as γ-glycidoxypropyltripropoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane And those treated with a silane coupling agent having a polar (hydrophilic) functional group such as a silane coupling agent having an amino group such as γ- (2-aminoethyl) aminopropylmethyldimethoxysilane.

  Accordingly, the hydrophilic dry silica in the present invention refers to a dry silica that is hydrophilic.

The present invention is a hydrophilic dry silica as described above, which is a silica having a specific surface area of 20 to 55 m ² / g measured by the BET method, and the following formula (1)
w ≦ 0.01 × S (1)
(W is the water content (wt%) of hydrophilic dry silica measured by the loss on drying method at 130 ° C., and S is the BET specific surface area (m ² / g) of hydrophilic dry silica. .)
Relating to silica satisfying

  Silica manufactured to satisfy all the above physical properties has the advantage that it can be added to the resin in an amount necessary to approximate the thermal expansion coefficient of the cured resin to that of a semiconductor element. There is also an advantage that a sufficient strength can be imparted. However, on the other hand, since the surface is hydrophilic and the specific surface area is relatively large, moisture is easily adsorbed on the surface during storage. The moisture adsorbed on the silica surface promotes and strengthens the aggregation between the silica particles, and the aggregation increases the viscosity of the resin composition, which makes it difficult to use.

  Furthermore, once the silica adsorbs moisture, even if it is dried and returned to a state that satisfies the above formula (1) again, the distance between the silica particles is reduced when the moisture evaporates due to drying. Aggregation is accelerated, aggregation is strengthened, and the physical properties are further deteriorated.

  Therefore, in the present invention, the silica produced so as to satisfy the formula (1) is maintained in a state satisfying the physical properties until use, that is, an environment in which moisture adsorption to the silica surface is suppressed. The one to save below. If hydrophilic dry silica is stored in this manner, a resin composition always having excellent physical properties can be obtained without worrying about the storage period in producing a resin composition by mixing the silica with a resin. be able to.

The method for storing ²⁰ to 55 m ² / g hydrophilic dry silica produced so as to satisfy the above formula (1) so as to maintain the state satisfying the above formula (1) is not particularly limited. A method of hermetically storing in a container having low moisture permeability is common. The moisture permeability of the container may be set as appropriate in consideration of the humidity, temperature, storage period, etc. of the storage environment. For example, it can be considered that the container is stored for a long period of time of 6 months or more in Japan regardless of the season. For example, a packaging container having a water vapor transmission rate of 1 g / m ² / day (value at 40 ° C./90% RH) or less, preferably 0.2 g / m ² / day (value at 40 ° C./90% RH) or less. It is preferable to encapsulate the silica. The water vapor transmission rate is a value measured according to JIS-Z-0208.

  Examples of such packaging containers include aluminum laminated bags, metal pail cans, etc. Aluminum laminated bags are preferred in terms of economy, ease of handling of packaging containers, and storage space. Specific examples of the aluminum laminated bag include lami zip AL series manufactured by Nippon Shokubai Co., Ltd., an aluminum laminated bag manufactured by Kite Chemical Industries, Ltd., a high barrier bag manufactured by Sunrise, and the like.

  Such a packing container is filled with dry silica fine particles by a method using an automatic measuring instrument equipped with a quantitative supply device such as a screw feeder or a table feeder. A known filling method such as a method of filling dry silica fine particles until a predetermined weight can be adopted without any limitation.

  When the packaging container is a pail can with an inner bag, after twisting the end with the opening of the inner bag, fasten it with vinyl tape or rubber band, and then close the lid of the pail can A method of fixing with a predetermined fastener can be employed. At the time of this sealing operation, the effect of the present invention is more exhibited if the inside of the inner bag or the pail can is replaced with air or nitrogen having a dew point of −20 ° C. or lower before sealing. Moreover, when a packaging container is an aluminum laminated bag, the method of heat-sealing an opening part is employable. In this sealing operation, if the inside of the aluminum laminate bag is replaced with air or nitrogen having a dew point of −20 ° C. or lower before sealing, it is easier to maintain the state of the formula (1).

Among the hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g, the following formula (2)
τ ≦ 240S ^−1.4 −0.07 (2)
(In the above formula, τ is the absorbance with respect to light having a wavelength of 700 m of an aqueous suspension containing hydrophilic dry silica at a concentration of 1.5 wt%, and S is the BET specific surface area (m ² / g of hydrophilic dry silica). ).)
The hydrophilic dry silica produced so as to satisfy the above has good dispersibility in the resin, and the resin composition using this as a filler has a lower viscosity.

  However, even dry silica having physical properties satisfying the above formula (2) may not satisfy the above formula (2) by adsorbing moisture. It is difficult to return to a state satisfying 2).

Therefore, in order to obtain a resin composition having excellent viscosity characteristics, hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g produced so as to satisfy the above formula (1) and the above formula (2), It is particularly preferable to store until use, while maintaining a state satisfying both of the above formulas (1) and (2). The method of preserving while maintaining the state satisfying the above formula (2) is the same as the method of preserving while maintaining the state satisfying the above formula (1), in a method of hermetically storing in a container having low moisture permeability. You can do it.

A hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g that satisfies the above formula (1) and the above formula (2) can be obtained, for example, by the production method described in JP-A-2008-19157.

The hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g produced so as to satisfy the above formula (1) and the above formula (2) is sealed in the above-mentioned packaging container, whereby the above formula (1) And it can preserve | save until it uses it, maintaining the state which satisfies both of (2).

  Silica thus stored exhibits excellent fluidity when kneaded with an epoxy resin or the like to form a resin composition, and can be suitably used as a sealing material for liquid crystals and semiconductors. In addition, it can be used for toner external additives, various resin films, paint additives for paint matting agents, etc., and anti-blocking agents without substantially considering the deterioration of physical properties due to the storage period.

  Examples and comparative examples are shown to specifically describe the present invention, but the present invention is not limited to these examples.

  In addition, various physical property measurements in the following examples and comparative examples are based on the following methods.

(1) BET specific surface area measurement:
Using a specific surface area measuring device (SA-1000) manufactured by Shibata Rikagaku Co., the nitrogen adsorption BET one-point method was used.

(2) Moisture measurement (loss on drying method):
Silica was put into a weighing bottle (made of glass, 60 mmφ × 75 mmH) whose weight was measured in advance, and the weight was measured. Let A (g) be the weight of the weighing bottle before loading silica, and B (g) be the weight of the weighing bottle after silica loading (including the weight of loaded silica). This silica-containing weighing bottle and an empty weighing bottle (made of glass, 60 mmφ × 75 mmH) whose weight was separately measured were allowed to stand for 30 minutes in a 130 ° C. constant temperature dryer. Let C (g) be the weight of an empty weighing bottle. Thereafter, the silica-containing weighing bottle and the empty weighing bottle were taken out of the dryer, placed in a desiccator (using diphosphorus pentoxide as a desiccant), and allowed to stand for 30 minutes. Then, the weighing bottle containing silica and the empty weighing bottle were taken out from the desiccator, and the weight was measured. At this time, the weight of the weighing bottle with silica is B ′ (g), and the weight of the empty weighing bottle is C ′ (g). And the moisture content w of the silica was computed by following Formula.
Water content w (% by weight) = 100 × [(BB ′) − (CC ′)] / [BA]
(3) Absorbance measurement:
Using a spectrophotometer (V-530) manufactured by JASCO Corporation, the absorbance τ of an aqueous suspension having a silica concentration of 1.5% by weight with respect to light having a wavelength of 700 nm was measured.

  As the measurement sample cell, a synthetic quartz cell (5-sided transparent, 10 × 10 × 45H) manufactured by Tokyo Glass Instruments Co., Ltd. was used.

  A water suspension having a silica concentration of 1.5% by weight was prepared as follows.

  0.3 g of silica and 20 ml of distilled water are placed in a glass sample tube bottle (manufactured by ASONE, inner volume 30 ml, outer diameter about 28 ml), and an ultrasonic cell crusher (BRANSON Sonifier II Model 250D, probe: 1 / 4 inches) was set so that the lower surface of the probe tip was 15 mm below the water surface, and silica was dispersed in distilled water under the conditions of an output of 25 W (amplitude 41%) and a dispersion time of 3 minutes.

(4) Viscosity of resin composition An epoxy resin composition was prepared as follows and the viscosity thereof was measured.

(Preparation of epoxy resin composition)
After 131.6 g of Toto Kasei epoxy resin ZX-1059 was weighed, 56.4 g of silica was added thereto. Then, it knead | mixed on the conditions for stirring time 5 minutes using the autorotation revolution planetary mixer (AR-250 by a Shinkey company), and obtained the epoxy resin composition. Thereafter, the resin composition was allowed to stand in a constant temperature bath at 25 ° C. for 2 hours.

(Viscosity measurement)
The resin composition was taken out from the thermostatic bath at 25 ° C., and the viscosity at 20 rpm and 2 rpm was measured using a BH viscometer.

Example 1
As described below, octamethylcyclotetrasiloxane was burned in a triple tube burner by the method described in JP-A-2008-19157 to produce hydrophilic dry silica.

Octamethyltetrasiloxane heated and vaporized in a mixed gas of oxygen and nitrogen (oxygen concentration 21%) was mixed so that R 2 _O would be 0.39, and then introduced into the burner center tube. Further, hydrogen is introduced into the first annular tube adjacent to the central tube so that R _SFL is 0.28, and oxygen is introduced into the second annular tube adjacent to the outside so that R _cmbtm is 0.83. Introduced. R 2 _O is obtained by dividing the amount of oxygen introduced into the central tube by the amount of oxygen necessary for complete combustion of octamethylcyclotetrasiloxane introduced into the central tube, and R _SFL is applied to the first annular tube. The amount of oxygen required for complete combustion of the introduced hydrogen is divided by the amount of oxygen required for complete combustion of octamethylcyclotetrasiloxane introduced into the central tube, and R _cmbtm is introduced into the second annular tube. The amount of oxygen produced is divided by the amount of oxygen necessary for complete combustion of the octamethylcyclotetrasiloxane introduced into the central tube.

The hydrophilic dry silica immediately after production had a BET specific surface area of 30 m ² / g, a water content of 0.10 wt%, and an absorbance τ of 1.35. The viscosity of the silica resin composition was 11 Pa · s at 20 rpm and 10 Pa · s at 2 rpm.

This hydrophilic dry silica was sealed in an aluminum laminated bag having a water vapor transmission rate of 0.1 g / m ² / day (value at 40 ° C./90% RH) and stored in an air atmosphere for 1 week. After storage, the aluminum laminate bag was opened, and the BET specific surface area, water content, absorbance, and viscosity of the resin composition were measured. The evaluation results are shown in Table 1.

Example 2
Manufacture, encapsulation, storage, and evaluation were performed in the same manner as in Example 1 except that the storage period after encapsulation was 1 month. The evaluation results are shown in Table 1.

Example 3
Manufacture, encapsulation, storage, and evaluation were performed in the same manner as in Example 1 except that the storage period after encapsulation was 1 year. The evaluation results are shown in Table 1.

Comparative Example 1
Manufacture, encapsulation, storage, and evaluation were performed in the same manner as in Example 3 except that it was sealed in a polyethylene bag having a water vapor transmission rate of 4 g / m ² / day (value at 40 ° C./90% RH). The evaluation results are shown in Table 1.

Comparative Example 2
Manufacture, encapsulation, storage, and evaluation were performed in the same manner as in Comparative Example 1 except that it was stored in a constant temperature and humidity chamber at a temperature of 55 ° C. and a humidity of 60 RH% for 2 weeks. The evaluation results are shown in Table 1.

Comparative Example 3
Manufacture, encapsulation, storage, and evaluation were performed in the same manner as Comparative Example 2 except that the storage period after encapsulation was 1 month. The evaluation results are shown in Table 1.

Comparative Example 4
After manufacturing, sealing, and storing in the same manner as in Comparative Example 3, the polyethylene bag was opened. Then, the silica was taken out from the opened bag and dried at 130 ° C. for 30 minutes. After drying, the silica was sealed in an aluminum laminate bag having a water vapor transmission rate of 0.1 g / m ² / day (value at 40 ° C./90% RH) and stored in an air atmosphere for 1 week. After storage, the aluminum laminate bag was opened, and the BET specific surface area, water content, absorbance, and viscosity of the resin composition were measured. The evaluation results are shown in Table 1.

In the table, G (S) is a calculated value of “0.01 × S” compared with the water content w of silica, and F (S) is a calculated value of “240S ^−1.4 −0.07” compared with the absorbance τ. Value.

Claims (4)

It is hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g, and is represented by the following formula (1)
w ≦ 0.01 × S (1)
(W is the water content (wt%) of hydrophilic dry silica measured by the loss on drying method at 130 ° C., and S is the BET specific surface area (m ² / g) of hydrophilic dry silica. .)
A method for preserving hydrophilic dry silica, characterized in that hydrophilic dry silica produced so as to satisfy the above-mentioned conditions is preserved until use while maintaining the state satisfying the above formula (1). It is hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g, and is represented by the following formula (1)
w ≦ 0.01 × S (1)
(W is the water content (wt%) of hydrophilic dry silica measured by the loss on drying method at 130 ° C., and S is the BET specific surface area (m ² / g) of hydrophilic dry silica. .)
And the following formula (2)
τ ≦ 240S ^−1.4 −0.07 (2)
(In the above formula, τ is the absorbance with respect to light having a wavelength of 700 m of an aqueous suspension containing hydrophilic dry silica at a concentration of 1.5 wt%, and S is the BET specific surface area (m ² / g of hydrophilic dry silica). ).)
The method for preserving hydrophilic dry silica, characterized in that the hydrophilic dry silica produced so as to satisfy the above conditions is preserved until use while maintaining the condition satisfying both of the above formulas (1) and (2). . It is hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g, and is represented by the following formula (1)
w ≦ 0.01 × S (1)
(W is the water content (wt%) of hydrophilic dry silica measured by the loss on drying method at 130 ° C., and S is the BET specific surface area (m ² / g) of hydrophilic dry silica. .)
Manufactured hydrophilic dry silica satisfying
Next, the hydrophilic dry silica is mixed with an epoxy resin to produce an epoxy resin composition,
A method for producing an epoxy resin composition, comprising maintaining the hydrophilic dry silica in a state satisfying the above formula (1) until the hydrophilic dry silica is produced and then mixed with the epoxy resin. It is hydrophilic dry silica having a BET specific surface area of 20 to 55 m ² / g, and is represented by the following formula (1)
w ≦ 0.01 × S (1)
(W is the water content (wt%) of hydrophilic dry silica measured by the loss on drying method at 130 ° C., and S is the BET specific surface area (m ² / g) of hydrophilic dry silica. .)
And the following formula (2)
τ ≦ 240S ^−1.4 −0.07 (2)
(In the above formula, τ is the absorbance with respect to light having a wavelength of 700 m of an aqueous suspension containing hydrophilic dry silica at a concentration of 1.5 wt%, and S is the BET specific surface area (m ² / g of hydrophilic dry silica). ).)
Manufactured hydrophilic dry silica satisfying
Next, the hydrophilic dry silica is mixed with an epoxy resin to produce an epoxy resin composition,
Until the hydrophilic dry silica is produced and mixed with the epoxy resin, the hydrophilic dry silica is maintained in a state satisfying both of the above formulas (1) and (2). Manufacturing method.