JP2001213662A - Cement composition with electrical insulation property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the inorganic cement composition for electric parts which has enough cement strength, electrical insulation property, superior sedimentation stability and fluidity. SOLUTION: In manufacturing the cement composition, the binder ingredient is first produced by adding primary or, at least, secondary alcohol with 20-60 portion into the hydrolyzed compound, being hydrolyzed after adding the silane compound shown in the general formula 1 (in the formula, X is preferably methyl group or mixture of methyl group and γglycidoxyalkyl group) with 1-30 portion into the water based colloidal silica containing silica solid at 1-40% with 5-60 portion, and then is well and evenly mixed with the cellulose type compound soluble in lower alcohol/water type solvent, as the thixotropic material, with 0.001-1 portion, the organic modified sumectite type clay, as the anti- sedimentation agent, with 1-5 portion, and the inorganic packing material such as silica powder with 90-120 portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement for electric parts which is used as a covering material and a filling material for electric resistors and capacitors with self-heating.

[0002]

2. Description of the Related Art In general, coating materials and fillers for electric parts are roughly classified into two types: organic materials and inorganic materials. As the organic type, an epoxy type, a silicone type and the like are known and put to practical use. However, general organic materials have poor heat resistance. Silicone materials having excellent flame retardancy have a high processing temperature (180 ° C. or higher), which limits the types of resistors that can be used, and is not preferable in terms of energy saving.

[0003] Under such circumstances, inorganic cement has begun to attract attention in recent years because of its excellent flame retardancy and low processing temperature. A common inorganic cement for electric parts is composed of several kinds of inorganic fillers and a binder containing substances such as aqueous colloidal silica and ethyl silicate which have a function of solidifying them.

However, conventional cements have insufficient electrical properties after hardening, have poor sedimentation stability, and have the disadvantage that the fillers settle out in a short time. For this reason, most of the workability is poor, such as the need for skill in the filling operation and the necessity of constantly stirring the cement. Further, due to this, the solid content concentration variation with the passage of time increases, which has a great adverse effect on product quality.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to provide an inorganic cement composition for electric parts which has sufficient cement strength and electric insulation, and has excellent sedimentation stability and fluidity. It is.

[0006]

The present inventors have conducted research on the development of an inorganic cement having both excellent electrical properties and workability. As a result, the alkylalkoxysilane has improved electrical insulating properties and has a functional group-containing structure. Among the alkyl trialkoxysilanes, it was found that the cement strength was improved by γ-glycidoxypropyl trialkoxysilane. In addition, it is found that a cement excellent in both sedimentation stability and fluidity can be obtained by using a cellulose compound soluble in a lower alcohol / water-based solvent as a thixo-material and an organically modified smectite-based viscosity in combination with an anti-settling material. Was.

According to the present invention, 5 to 60 parts of an aqueous colloidal silica containing 5 to 40% of a silica solid component are added with a compound represented by the general formula 1

Embedded image (Wherein, X is an alkyl group having 1 to 10 carbon atoms or an alkyl group having a functional group or a lower alkoxy group, Y,
Z and W are an alkyl group having 1 to 10 carbon atoms or a lower alkoxy group, respectively. 1) The silane compound represented by
The hydrolysis product obtained by adding 1 to 30 parts of a mixture of two or more kinds or two or more kinds is added to 20 to 60 parts of one or two or more alcohols, 0.001 to 1 part of a thixotropic material, The gist is an inorganic cement composition obtained by mixing 5 parts and 90 to 120 parts of an inorganic filler.

In a preferred embodiment of the cement composition of the present invention, in the general formula 1, X is a methyl group, or X is a methyl group and a functional group-containing alkyl group, preferably a γ-glycidoxyalkyl group. Is a mixture of In a preferred embodiment of the cement composition of the present invention, a cellulose compound soluble in a lower alcohol / aqueous solvent is used as a thixotropic material, and an organically modified smectite clay is used as an anti-settling material.

In a most preferred embodiment of the cement composition of the present invention, 5 to 60 parts of an aqueous colloidal silica containing 1 to 40% of a silica solid component is added to a general formula 1 (where X is a methyl group, or A mixture of a methyl group and a functional group-containing alkyl group, preferably a γ-glycidoxyalkyl group.) 1 to 30 parts of a mixture of one or more silane compounds One or more alcohols 2 are added to the hydrolyzed hydrolysis product.
A binder component containing 0 to 60 parts as a binder component, 0.001 to 1 part of a cellulose compound soluble in a lower alcohol / aqueous solvent as a thixotropic material, 1 to 5 parts of an organically modified smectite clay as an anti-settling agent, silica 90 to 120 parts of an inorganic filler such as powder and titanium oxide are sufficiently mixed to form a uniform cement composition.

[0010]

DETAILED DESCRIPTION OF THE INVENTION As aqueous colloidal silica, it is preferable to use colloidal silica having high miscibility with a solvent. Quantitatively, 5 to 60 parts of aqueous colloidal silica containing 5 to 40% of a silica solid component is used. If the amount is less than 5 parts, the setting power is insufficient, and the cement strength is reduced. If the amount exceeds 60 parts, the viscosity of the cement increases, which impairs workability.
If the silica solids concentration is less than 5%, the cement strength is reduced, and if it exceeds 40%, gelation is undesirably caused.

In the silane compound represented by the general formula 1, an alkyl trialkoxy silane gives a particularly high insulation resistance value. However, as the alkyl chain becomes longer, the water solubility after hydrolysis decreases, methyl trialkoxy silane is preferred. . Further, by using a functional group-containing alkyl trialkoxysilane, preferably γ-glycidoxypropyl trialkoxysilane, the cement strength can be increased. Quantitatively, one or two silane compounds
1 to 30 parts of a mixture of the above species are used. If the total ratio of the silane compounds is less than 1 part, both the electrical insulation resistance value and the cement strength will be reduced. If it exceeds 30 parts, gelation occurs.

The alcohol is preferably a lower alcohol, especially methanol, from the viewpoint of quick drying and water solubility of cement. Quantitatively, 20 to 60 parts of a mixture of one or more alcohols is used. If it is less than 20 parts, the viscosity of the cement increases, and cracks are apt to occur during predrying.
If the amount exceeds the limit, the sedimentation stability decreases.

As the thixo-material, it is preferable to use a cellulose-type thixo-material which is soluble in a lower alcohol / water mixed solvent. Although the amount of addition varies depending on the molecular weight of the cellulose used, it is preferable that the viscosity at 20 ° C. of a 2% aqueous solution, which is a general index of the molecular weight, be 25 to 4000 cPs. The addition amount is 0.001 to 1 part. If the amount is less than 0.001 part, the sedimentation stability decreases, and if it exceeds 1 part, the cement viscosity increases and cracks are liable to occur during preliminary drying.

As the anti-settling material, an organically modified smectite clay is exemplified as a preferable one. Inorganic clays such as bentonite-based viscosities, which are generally well known, have very low effects in alcohol / water systems. It is preferable to use an alcohol / water-based solvent that effectively exhibits the ability to prevent sedimentation. Among them, organically modified smectite clay is effective. The addition amount is 1 to 5 parts. Less than 1 part has no effect, and adding more than 5 parts does not change the effect.

The inorganic filler is used in an amount of 90 to 120 parts. If the amount is less than 90 parts, cracks are likely to occur in the drying stage, and the skin becomes large. If it exceeds 120 parts, the viscosity of the cement increases and the fluidity decreases. Further, as the type, a material having a higher volume resistance is preferable from the viewpoint of insulation resistance. For example, mica, silica, alumina, titanium oxide and the like can be mentioned. There are various shapes such as a particle shape, a fiber shape, and a scale shape, but any shape may be used. However, it is necessary to consider the cement viscosity and the volume change during drying. When the ratio of fibrous or scaly ones is high, the change in volume during drying is small, but the viscosity of the cement is extremely increased and workability is significantly impaired. Similarly, particle size has a significant effect on fluidity. As the ratio of large particles increases,
The change in volume during drying is small, but the fluidity is impaired.
The converse is true when the proportion of small particles is high.

[0016]

As described above, the present invention has the workability due to the high sedimentation stability, and the embodiment 3 is selected by selecting the silane compound.
Thus, it is possible to provide a cement which has not been hitherto and has high insulation resistance and strength. INDUSTRIAL APPLICABILITY The cement composition of the present invention has excellent sedimentation stability and workability, and is therefore advantageous for improving the efficiency of coating and filling operations of electric resistors and capacitors. In addition, it has high electrical insulation, solvent resistance, and excellent heat resistance without flaming when overloaded. It has good moisture resistance, has sufficient physical properties and safety as a coating or filler for electric parts, and brings great benefits to the entire industry.

[0017]

EXAMPLES The present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples.

Examples 1 to 3 and Comparative Examples 1 and 2 Various silanes were added to 20 parts of aqueous colloidal silica at the compounding ratios shown in Table 1 and the mixture was stirred at room temperature for about 45 minutes to effect hydrolysis. Let it. Add methanol 3
8 parts, 2 parts of butyl cellosolve are added as binder components, and 0.01 part of a cellulose-based thixotropic material, 2 parts of an organically modified smectite-based anti-settling material, and inorganic filler 106
The parts were sequentially added under stirring to form a uniform paste. In addition, Comparative Examples 1 and 2 also show the case where the thixotropic material was 0 part and the case where the sedimentation preventing material was 0 part in Example 2. Further, a cement obtained by adding the same filler to a commercially available binder of the same ratio in the same ratio and forming a cement is shown as a reference example.

[0019]

[Table 1] Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3水性 aqueous colloidal silica 20 parts 20 parts 20 parts 20 parts 20 parts ────────────────────────────────── Tetraethoxysilane 0 parts 0 parts 8 parts 0 parts 0 parts ────────────────────────────────── Methyltriethoxy Silane 8 parts 8 parts 0 parts 8 parts 5 parts γγ-criticoxy Fluorotriethoxysilane 0 parts 0 parts 0 parts 0 parts 2.5 parts ────────────────────────────────── Methanol 38 Part 38 part 38 part 38 part 38 part ─────────────────────────────゛ Cellulosol 2 parts 2 parts 2 parts 2 parts 2 parts セ ル ロ ー ス Cellulose Thixotropic material 0.01 part 0 part 0.01 part 0.01 part 0.01 part ────────────────────────────────── Organically modified smectite System 0 part 2 part 2 part 2 part 2 part ────────────────────────────────── Anti-settling material Inorganic filling Material 106 parts 106 parts 106 parts 106 parts 106 parts ────────────────────────────────── Appearance Settling paste Form Paste Paste Paste Some liquid Sedimentable No sedimentation No sedimentation No sedimentation Specific gravity 1.9 1.9 1.9 1.9 1.9 pH 4.4 4 4 4 4 ─────── ────────────────────── ─────

As can be seen from the appearance section shown in Table 1, sedimentation stability is exhibited only when the thixotropic material and the anti-settling material are used in combination. Viscosity measurements were made to quantify it. Fill a cylindrical container with a diameter of 57 mm and a height of 70 mm with cement to a height of about 40 mm,
A sample for measurement was used. The measuring method is a Brookfield viscometer (rotor: TA, 6 rpm, cement temperature 25 ° C.)
, The rotor was installed so as to rotate at a height of about 10 mm from the bottom, and a total of five measurements were taken immediately after kneading, 30 minutes, 1 hour, 2 hours, and 6 hours. The results are shown in Table 2.

First, in the case of a commercially available binder, the viscosity immediately after kneading is high even though the filler concentration is uniform. Such low fluidity lowers the dischargeability from nozzles, pumping performance, and the like in the manufacturing process, and has a large adverse effect on work efficiency. In order to achieve the same fluidity, the concentration of the filler must be reduced, which causes an adverse effect such as a large change in volume during drying. On the other hand, as is clear from the results of Comparative Examples 1 and 2 in Table 2, a stable anti-settling effect cannot be obtained by using the thixotropic material or the anti-settling material alone. That is, as in the embodiment, a stable settling prevention effect can be obtained only when both are used together.

[0022]

[Table 2] ───────────────────────── Reference Example Comparative Example 1 Comparative Example 2 Example 2 ──────────直 後 Immediately after kneading 31467 4800 7467 10400 ──────────────────── 600 30 minutes after kneading 49600 Heart ゛ Cake formation 164533 16800 Viscosity measurement not possible ────────────────────────── ───── / cPs 〃After 1 hour 54933 − Heart ゛ Cake formation 19733 Measurement not possible ─────────────────────────────── 8002 hours later 56800 − − 25067 ─────────────────────────────── 〃6 hours later Heart ゛ cake formation − − 26100 measurement Not possible ────────────────────────────── ───

Table 3 shows a sample in which a wound resistance element was filled in a ceramic case with cement, air-dried at 24 hours / room temperature, dried at 90 minutes / 50 ° C., and cured at 130 ° C./50 minutes. Various physical properties measured using the same are shown.

Hereinafter, measurement and evaluation methods will be described. Insulation resistance value: Resistance was measured when a voltage of 100 V was applied using a SM-10E ultra-super insulation meter manufactured by Toa Denpa Kogyo. Moisture resistance test: According to JIS C-5202 7.5 Moisture resistance test (40 ° C., humidity 90%, 24 hours). Withstand voltage test: AC1000V / 1min was applied with an APT-8741 withstand voltage meter manufactured by Toa Denpa Kogyo. Cement strength: Cement was pressed with an iron metal piece having a pressing portion having a shape of 1 × 3 mm (area 3 mm ² ), and the load at which dents were formed was measured. Solvent resistance: immersed in xylene for 1 hour and evaluated whether the cement strength is reduced. Non-flammability: 110 W of electric power, which is an overload power, was applied to the resistor, and electricity was supplied until the resistor was opened, and observation was performed.

[0025]

[Table 3] Example 1 Example 2 Example 3 ───────────── Insulation resistance value Before moisture resistance test 1.0 × 10 ³ 1.0 × 10 ⁷ 3.5 × 10 ⁶ ─────────────────── ───── / MΩ After moisture resistance test 0.8 × 10 ³ 0.3 × 10 ⁷ 1.0 × 10 ⁶ ──────────────────────────── 0% before and after moisture resistance test 0% 0% Specific resistance change rate ─────────────────────────────── Resistance Voltage test OK OK OK ─────────────────────────────── Cement strength 8kgf 7kgf> 10kgf ────────溶 剤 Solvent resistance No change No change No change ─────────── ─────────────────── Nonflammable No flaming No flaming No flaming ───────────────── ──────────────

From the results shown in Table 3, the use of methyltriethoxysilane improves the insulation resistance. It exhibits high electrical insulation due to an alkyl group directly bonded to a silicon atom. In addition, cement strength is improved by the combined use of γ-glycidoxypropyltriethoxysilane. This is γ
Due to the bifunctionality of glycidoxypropyltriethoxysilane. That is, it is considered that this is because the silanol group binds to the surface of the inorganic filler particles and the other glycidoxy group condenses, and the bond between the particles becomes stronger. In addition, both the solvent resistance and the nonflammability are good, and it can be said that the safety as an electric component is sufficiently ensured.

As described above, the present invention has excellent workability due to high sedimentation stability, and also has high insulation resistance and strength as in Example 3 by selecting a silane compound.
It is possible to provide a cement that has not been provided in the past.

[0028]

Industrial Applicability The cement composition of the present invention has excellent sedimentation stability and workability, and is therefore advantageous for increasing the efficiency of covering and filling operations of electric resistors and capacitors. In addition, it has high electrical insulation, solvent resistance, and excellent heat resistance without flaming when overloaded. It has good moisture resistance, has sufficient physical properties and safety as a coating or filler for electric parts, and brings great benefits to the entire industry.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C04B 24:02 C04B 24:02 24:38 24:38 Z 14:10) 14:10) Z 111: 92 111: 92 F-term (reference) 4G012 PA06 PA11 PB04 PB15 PB40 PB41 4J038 BA022 DL031 DL051 HA446 HA496 HA526 JA17 KA08 MA15 NA21 PB09 5G303 AA10 AB01 AB20 BA12 CA07 CA09 CC08 CD04 CD11

Claims (5)

[Claims] 1. An aqueous colloidal silica containing 5 to 40% of a silica solid component is mixed with 5 to 60 parts of a general formula 1 (Wherein, X is an alkyl group having 1 to 10 carbon atoms or an alkyl group having a functional group or a lower alkoxy group, Y,
Z and W are an alkyl group having 1 to 10 carbon atoms or a lower alkoxy group, respectively. 1) The silane compound represented by
The hydrolysis product obtained by adding 1 to 30 parts of a mixture of two or more kinds or two or more kinds is added to 20 to 60 parts of one or two or more alcohols, 0.001 to 1 part of a thixotropic material, An inorganic cement composition obtained by mixing 5 parts and 90 to 120 parts of an inorganic filler. 2. The cement composition according to claim 1, wherein in the general formula 1, X is a methyl group. 3. The cement composition according to claim 1, wherein in formula 1, X is a mixture of a methyl group and a functional group-containing alkyl group. 4. The cement composition according to claim 3, wherein the functional group-containing alkyl group is a γ-glycidoxyalkyl group. 5. The cement composition according to claim 1, wherein a cellulose compound soluble in a lower alcohol / aqueous solvent is used as the thixotropic material, and an organically modified smectite clay is used as the anti-settling material.