JPH03232757A - Highly electrical insulating inorganic composition - Google Patents

Abstract

PURPOSE:To obtain a composition useful for adhesion, packing and coating, providing high electrical insulating properties and bond strength, not causing reduction in strength by water absorption, by blending specific silica aqueous gel with silica fine powder and inorganic refractory powder. CONSTITUTION:100 pts.wt. calculated as SiO2 of silica aqueous gel having 5-200mu average particle diameter and >=30 molar ratio of SiO2/M2O (M is alkali metal atom, amine molecule or quaternary ammonium group) is blended with 0.2-200 pts.wt. silica fine powder having 5-500mu particle diameter and 100-20,000 pts.wt. inorganic refractory powder having 0.5-400mu particle diameter to give an inorganic composition. The silica aqueous sol is readily obtained by dealkalizing a diluted aqueous solution of water glass with a cation exchanger or deflocculating the silica neutralized with an acid or another method and is usually a liquid wherein colloidal silica is stably dispersed into water as a medium.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to the improvement of an inorganic composition consisting of a silica sol and an inorganic refractory powder. Adhesion, filling, or filling between similar or dissimilar materials such as ceramics, glass, slate, aluminum, stainless steel, iron, and other metal materials that require high insulation (not to mention high adhesive strength), or these materials. Used for surface coating.

(Prior Art) JP-A-48-95656 discloses a composition obtained by mixing an acidic silica sol of 7 to 150 mμ, a crystalloid silicate liquid containing no alkali metal ions, and an inorganic refractory powder. has been done.

Japanese Patent Publication No. 56-58544 discloses that an aqueous silica sol, an inorganic composition or refractory powder of 01μ to 20μ,
Inorganic compositions containing pigments, aggregates, adjuvants, etc. are disclosed.

(Problems to be Solved by the Invention) Good adhesive strength cannot be obtained depending on the composition prepared by mixing an acidic silica sol with a crystalloid silicate liquid as described in JP-A No. 48-95656, and Good electrical insulation cannot be obtained with the composition described in Japanese Patent Publication No. 56-38544, which is a mixture of aqueous silica sol, inorganic fibers, and refractory powder.

When using adhesive to assemble electrical parts,
For example, the adhesive part between the light bulb crow and the base, and the electric heater.
It goes without saying that the parts where the coils and the like are fixed need to have good adhesion, but at the same time, since high voltage is applied to those parts, high electrical insulation is essential.

Further, the K1)1 strength of the cured product of the above composition gradually decreases due to the adsorption of moisture in the atmosphere.

The present invention solves these problems, provides high electrical insulation properties and high theoretical adhesive strength, does not cause strength deterioration due to moisture absorption, and is suitable for use with ceramics, glass, slate, aluminum, stainless steel, iron, and other materials. It is an object of the present invention to provide a composition that achieves improved adhesion between similar or dissimilar materials such as metal materials.

(Means for solving &! problem) The first composition of the present invention has an average particle size of 5 to 200 mμ and 5iOz/MtO (M represents an alkali total island atom, an amine molecule, or a quaternary ammonium group). 100 parts by weight of a silica aqueous sol having a molar ratio of 30 or more as Sin, 2 to 200 parts by weight of fine powder silica α with a particle size of 5 to 500 mμ, and 100 to 100 parts of inorganic refractory powder with a particle size of α5 to 400 μm.
It is obtained by mixing with 20,000 Judobe. Further, the second composition of the present invention contains 100 parts by weight of 8102, an aqueous silica sol having an average particle diameter of 5 to 200 mμ and a no molar ratio of 8i0z/MzO (M is the same as above) 60 or more, and 5i02/M' , Q (Mp represents lithium, sodium, potassium, an amine molecule, or a quaternary ammonium group) alkali silicate aqueous solution with a molar ratio of 1 to 3o as solid content 1) to SOO parts by weight, and a particle size of 5 to 500
mμ fine powder silica α5 to 500 parts by weight and particle size α5
It is obtained by mixing 100 to 100,000 parts by weight of an inorganic refractory powder of ~400μ.

The aqueous silica sol used in the present invention can be obtained by dealkalizing a dilute aqueous solution of water glass with a cation exchanger, or by
It is easily obtained by peptizing silica after neutralization with acid, and is usually a liquid material in which colloidal silica is stably dispersed in water as a medium. The colloidal silica has an average particle size Fis of ~200 mp, preferably 10 ~
150 mμ is good. The shape of the colloidal silica particles may be spherical or non-spherical. In addition, this silica aqueous sol may be either alkaline or acidic.
30 as a molar ratio of o, /M, o (M is the same as above)
~1600 is preferably used. Examples of amines contained in this sol include methylamine, ethylamine, triethanolamine, and triethanolamine, and examples of quaternary ammonium groups include tetramethylammonium, monomethyltriethanolammonium, and ingropyr. Examples include triethanolammonium and tetraethanolammonium. This silica aqueous sol preferably has a Sin concentration of 1 to 50% by weight.

The fine powder silica used in the present invention has a particle size of 5 to
500 m- is good, and its shape may be spherical or non-spherical, and may be crystalline or non-crystalline, but preferably non-crystalline. Although there are a gas phase method using silicon tetrachloride as a raw material and a neutralization method using silicate powder as a raw material, fine powder silica from either method may be used. The finely powdered silica may be added to the silica aqueous sol in the form of a powder, or in the form of a suspension in a medium such as water.

The alkali silicate aqueous solution used in the present invention is a silicate aqueous solution containing alkali metal ions such as lithium, sodium, and potassium, amines, and quaternary ammonium groups. Examples of this amine include methylamine, ethylamine, ethanolamine, triethanolamine, and the like. Examples of quaternary ammonium groups include:
Examples include tetramethylammonium, monomethyltriethanolammonium, inopropyltriethanolammonium, and tetraethanolammonium.
The molar ratio of 8 i0z/M'zO (M' is the same as above) is 1 to 30, preferably 1 to 10. The concentration used is 1 to 60 weight US, preferably 10 to 50 weight US, and these may be used alone or in combination.

Examples of the inorganic refractory powder used in the present invention include quartz,
Powder of silica, feldspar, aluminum silicate, silconitum silicate, mullite, zirconia, alumina, silicon nitride, silicon carbide, talc, mica, etc., with particle size (L5
~400 tones is good, and powder of glass fiber, potassium titanate, fiber, etc. with a long axis length α1~1
For example, the length of the short axis is about 1) to 20μ. These inorganic refractory powders can be used alone or in any combination or as desired.

The composition of the present invention may further contain arbitrary components in addition to the above-mentioned components, as long as the purpose of the present invention is achieved.
Examples of these additional ingredients include bentonite clay≠mineral powder as an anti-settling agent, cellulose acetate, ethyl cellulose, hydroxyethyl cellulose, and natural and synthetic organic polymer substances such as polyvinyl chloride and polyvinyl alcohol. .

Examples of the coloring agent include titanium oxide, iron oxide, chromium oxide, and inorganic or organic pigments for coloring such as Bosta color.

In addition, to impart fluidity and adhesion, various surfactants and surface treatment agents may be added. Examples of preferable silane coupling agents include vinyltris (β). -methoxyethoxy)silane: CH
,=CH8i (QC,H40CHs), :vinyltriethoxysilane: CH,=CH8i(0CzHs)
s: Vinyltrimethoxysilane: CH,=CH8i (QC
)1. ), : Vinyltriacetoxysilane: 0Hs=CH8i glycidoxypropyltrimethoxysila γ-(β-aminoethyl)aminopropyltrimethoxysilane: H1NC
2H4NHC1H,8i (ocH,), :r-(β-
aminoethyl)aminopropylmer-aminopropyltriethoxysilane: HINCIH@8i (OClHg
)1: N-phenyl-r-aminopropyltrimethoxysilane: c@H, Ni1csu, si (0CH
I) 1; γ-anilinopropyltrimethoxysilane:
C, HsNHCsH, Si (OCHm), etc.

These silane coupling agents can convert silica aqueous sol into S
cL as the amount of the coupling agent or its hydrolyzate based on 100 parts by weight as iol
05 to 5 GO parts by weight, preferably about 15 to 100 parts by weight.

Water can also be added to adjust the viscosity or solids concentration of the adhesive. Furthermore, a small amount of methanol, ethanol,
In addition, it may contain a hydrophilic organic solvent and the like.

Mixing for preparing the composition of the present invention can be easily carried out using conventionally known conventional stirrers, mixers, and the like.

Mixture of the above ingredients! , - degrees or in any order.

The mixing is preferably carried out at a temperature and pressure that does not cause scorching, and in the atmosphere, the temperature is between 5°C and 40°C. At a temperature of about C, α5
A preferable composition can be obtained by mixing between 5##f and 5##f.

A preferred composition of the present invention has a solid content of 60 to 901
It contains about the same amount as water, and shows 10 to 10,000 voids at 20°C. When stored under closed conditions at varying temperatures, it has storage stability that does not cause f'in for more than several months.

Although the composition of the present invention is cured by the 'l@- strategy, particularly good cured products are obtained when heated at 80 DEG to 500 DEG C.

(Function) Although it is difficult to completely elucidate the interaction between the silica % fine powder silica and the alkali silicate used to prepare the composition W of the present invention, it is thought to be as follows.

The silica particles in the silica aqueous sol have alkali ions adsorbed on their surfaces to stabilize their dispersion. In a composition that does not contain finely powdered silica, as the composition absorbs moisture in the air immediately after drying, the alkali ions can freely move in the cured product under high voltage, so that the electrical insulation resistance gradually decreases. However, since finely powdered silica has a very large specific surface area, it takes 19 minutes to add 7 liters of fine powder to a 7 liters aqueous sol. The alkali ions in the aqueous silica sol are adsorbed on the surface of the fine silica powder, resulting in a total of 5i (J
, 7M20 (M is the same as above), the molar ratio increases, and it is considered that the electrical insulation property decreases.

The alkali 7-silicate found in the silica aqueous sol can be produced by drying and curing the cured product of one composition by coating the surface of the 7-liquid particles, finely powdered silica particles, inorganic refractory powder particles, etc. in the silica aqueous sol. Significantly reduces specific surface area. As a result, the number of 10H groups present in the unit surface area of these particles decreases.

It is thought that this reduces adsorption of moisture after drying, resulting in improved electrical insulation.

Furthermore, conventionally formulated adhesives consisting only of silica aqueous sol and inorganic refractory powder.

After drying and curing, a phenomenon was observed in which the 9Ii degree of the cured product decreased due to moisture adsorption and the adhesive layer peeled off, but it is thought that such a phenomenon will not occur because moisture adsorption is difficult to occur with the composition according to the present invention. It will be done. However, if the silica aqueous sol used has a particle diameter smaller than 5, the composition will have poor stability;
If it is larger than j, the particles of the aqueous sol will tend to settle and solidify in the composition.

S10,7M20 (M is the same as above) Nomolar ratio is 30
Below, a part of the surface of the colloidal silica particles is easily dissolved, so a molar ratio of 1 is less preferred, but a molar ratio of 1 (500
It's hard to get a sol that's even more expensive than that.

If the 8102 concentration of the aqueous silica sol used is too high, stability will be poor and the composition will tend to thicken and gel; if the S + Os concentration is too low, the composition will have poor binding strength. Therefore, a preferable density wIA song is about 96 to 50 weight per weight.

If the particle size of the fine powder silica used is 500 mμ or more, the specific surface area is small, and if it is less than 5 mμ, it does not exist stably.
It is about 500 mμ. By examining the particle size of the refractory powder used, a composition with good row properties can be obtained.

However, to prepare the composition, the silica aqueous sol
Against the 100 Judo Club as 102! 2 powdered silica
When the ratio is 00 parts by weight or more, 5i02/M, 0 (
M is the same as above) The molar ratio is too high and the composition lacks stability. If fc is less than 12 parts by weight, an electrically insulating cured product cannot be obtained.

In addition, the amount of inorganic refractory powder is 20,000 parts by weight or more.

The composition lacks fluidity suitable for workability, strength of the cured product, etc., and if the composition is less than 100 parts by weight, cracks and shrinkage tend to occur in the cured product when drying and curing the composition.

The second composition of the invention is an improved composition obtained by adding an aqueous alkali silicate solution to the composition. SiO,/M of the alkali silicate aqueous solution used
'20 (M' is the same as above) molar ratio is 30 or more and F
Below i1, both lack the ability to cover the particle surface. Also, to the rlI degree of alkali silicate added, 60J
If the temperature is above 100 lbs., the stability is poor and the composition tends to thicken and gel. In addition, if the molecular weight is less than 13iLjl, the ability to cover the particle surface is poor.

When adding this alkaline liquor bath, 8+0. If the alkali silicate X bath [k solid content is more than 50° There is no current method. In addition, if the fine powder silica is SOO heavy grade or higher, 5l (J2/MzO(
M Fi The ramole ratio increases too much and lacks stability, and if it is less than 15 parts by weight, a highly insulating cured product cannot be obtained, and if the inorganic refractory powder is more than 100,000 parts by weight, the composition is not suitable for workability. The composition lacks fluidity and strength of the cured product, and if the composition is less than 1001 Ejk parts, the cured product is likely to crack or shrink when drying and curing the composition.

Therefore, the preferred first composition of the present invention has an average particle size of 5 to 200 mμ and S"Ox/MtO (MH same as above).
A silica aqueous sol having a molar ratio of 30 or more is 810. 100 parts by weight of fine powder silica α2-200 with a particle diameter of 5 to 500 mμ, and a particle size of [15 to 400 mμ].
This is a composition obtained by mixing 100 to 20,000 μm of inorganic refractory powder.

In the preferred second composition of the present invention, an average particle size of 5 to 20
0 mu and S 1027M, <J (M k'X 'f
100ml/lt part of 810, a 7-force aqueous sol having a molar ratio of 30 or more, and 8tO,/
m', 0 (M' is the same as above) molar ratio of alkali silicate aqueous solution of 1 to 50 cL1 to 500 as total solid content
fiili and fine powder silica α with a particle size of 5 to 500 mμ
The composition is a mixture of 5 to 5 oO parts by weight and 100 to 1 ooooo parts by weight of an inorganic refractory powder having a particle size cL of 5 to 400 microns.

(Example) The following commercially available silica aqueous sols A1 to A4, commercially available alkali silica) Bl''Bs, commercially available fine powder silica C1, commercially available inorganic refractory powder D1, and commercially available silane coupling agents E1 to Es k prepared.

A1° Colloidal 7 force particle size 10-20 m/J
.

5i02/Na1O (D molar ratio 66, Sin, alkaline aqueous sol with concentration 40wks.

A particle size of tocolloidal silica: 70-100 rput
.

8ioz/NazO nomolar ratio i) 1) 500. 8i0
1) & 40 weight 1llts alkaline aqueous sol.

A3: Colloidal particle size 10-20 mat
.

8102/Na 20 Nomo/' ratio 500.8iO2
Acidic aqueous sol of 20Jk'.

A4: 8tO obtained by diluting A with water, 9 degrees 531!
Blood related alkaline aqueous sol.

B1:a1) degree 201 quantity 4.8i0. /Li, 0 Lithium silicate aqueous solution with a no molar ratio of 4.5.

B goose: I# degree 40 heavy child, 8i0. /M'20 (M
' is a quaternary ammonium group) whose molar ratio is 14.0.
Grade ammonium silicate aqueous solution.

Bs: 1) degree 50 ] 1ji%, 5102/Na
A sodium silicate aqueous solution with a molar ratio of tQ of A6.

Ba: 51) A potassium silicate aqueous solution with a weight ratio of 301 degrees and a molar ratio of O to SiO, / of 4.0.

B: An aqueous sodium silicate solution of 1°C and 5% weight obtained by diluting B with water.

C1: Commercially available fine powder silica obtained by a gas phase method with a particle size of 12 mμ.

D is quartz powder having a particle size distribution of α5 to 400μ.

D2: Alumina powder with a particle diameter distribution of α5 to 400μ.

El: γ-methacryloxyglobiltrimethoxysilane.

E,: r-glycidoxyglobiltrimethoxysilane.

R3: γ-(β-aminoethyl)aminopropyltrimethoxysilane.

The performance test of the composition and the cured product was carried out in the following manner - Stability test The composition was kept in a sealed glass container at 20C for 24 hours to determine whether the product had fluidity or not.

Curing test: A layer of 21 DI was applied to the entire surface of a glass board measuring 20 square meters vertically and horizontally. The presence or absence of cracks in the cured product is visually determined, the pencil hardness is measured, and a hardness of 2H or more is considered hard.
Anything less than this n is considered insufficient.

Electrical insulation test was outsourced. He filled a glass tube measuring 8 m long, inner diameter 61 m long, and 20 m long with a layering agent. After leaving it in a room with a diameter of A1 @ 9 o'clock in the center of both ends, a direct current was applied from a battery. 500V
Apply the power supply voltage and measure the electrical resistance.

Subsequently, the two glass plates are bonded together by heating and drying at 200° C. for 30 minutes to harden. Next, after cooling to room temperature, the fixtures were attached to both sides of the glass board using a commercially available strong adhesive, and a tensile test was performed. ! Tension is applied in the perpendicular direction at a speed of 1 ml 7 minutes using a screwdriver, and the tension is measured when the adhesion is broken.

Example 1 A silica aqueous sol, finely powdered silica, and inorganic refractory powder were mixed in a mixer at room temperature for 2 hours to obtain a composition Ql-Qs as shown in Table 1.

Example 2 Compositions Q6~ as shown in Table 1 were obtained by mixing 7 licorice aqueous sol, aqueous alkali silicate solution, fine powder paste, and inorganic refractory powder in a mixer at room temperature for 3 hours with the composition shown in Table 1. Q
I got 1s.

Example 3 Aqueous silica sol, aqueous alkali silicate solution, fine powder silica, inorganic refractory powder, and 7-rank coupling agent were mixed at room temperature for 3 hours to form the composition Q shown in Table 3. ~I got Qne.

Next, the compositions Q1 to Qn and their cured products were subjected to performance tests according to the above test method, and the results shown in Tables 2 and 4 were obtained.

Comparative Example 1 In the same manner as in Example 1, a composition R1-84 having a ratio of ff 1 l was prepared with the composition shown in Table 1 and tested by the above test method, and the results shown in Table 2 were obtained. Composition 1 of the comparative example has low insulation resistance, and the insulation resistance is low! Hai! I! After conditioning - gelation occurred while standing overnight. The cured product of 几S had cracks, making it difficult to measure the insulation resistance, so it was not measured. Since the composition of R4 could not be adjusted, the insulation resistance could not be measured.

Comparative Example 2 In the same manner as in Example 2, compositions R5 to R9 of comparative examples were prepared with the compositions shown in Table 1 and tested by the above test method, and the results shown in Table 2 were obtained. R3t: had low insulation resistance, and R6 underwent gelation during the night after adjustment. For fL, gelation occurred while the sample was left to stand overnight after adjustment, and for B, cracks appeared in the cured product, making it difficult to measure the insulation resistance, so it was not measured. Since it was impossible to adjust the vI4 of R9 as a composition, the insulation resistance could not be measured.

(Effects of the Invention) The composition of the present invention can be easily produced, and when it is cured, K changes into a desirable cured product only by heating from room temperature to 300°C, exhibiting significantly high electrical insulation properties, and exhibiting high electrical insulation properties. This brings about a significant improvement in bonding between the same or different types of materials such as ceramics, glass, slate, aluminum, stainless steel, iron, and other metal ring materials that require bonding.

The composition of the present invention has excellent long-term stability as a composition, and also has excellent fluidity and workability that can be passed through automated equipment in operations such as adhesion, filling, and coating. Also, no cranking or shrinkage occurs during curing. moreover.

It has heat-on-yoke resistance that does not cause damage to adhesives, fillings, and coatings even after curing due to heat shock during stationary molding. It can also be used for filling and coating.

Claims (2)

[Claims] (1) Average particle diameter 5-200 mμ and SiO_2/M_2
100 parts by weight of a silica aqueous sol having a molar ratio of O (M represents an alkali metal atom, an amine molecule, or a quaternary ammonium group) of 30 or more as SiO_2, and a particle size of 5 to 5.
0.2 to 200 parts by weight of 500 mμ fine powder silica and 100 to 2000 parts of inorganic refractory powder with a particle size of 0.5 to 400 μ
0 parts by weight of a highly insulating inorganic composition. (2) Average particle diameter 5 to 200 mμ and SiO_2/M_2
100 parts by weight of SiO_2 is an aqueous silica sol having a molar ratio of O (M has the same meaning as in claim (1)) of 30 or more, and SiO_2/M'_2O (M' is lithium, sodium, potassium, Amine molecule or quaternary
0.1 to 500 parts by weight of an aqueous alkali silicate solution with a molar ratio of 1 to 30 (representing an ammonium group) as a solid content, and 0.5 to 50 parts by weight of fine powder silica with a particle size of 5 to 500 mμ.
0 parts by weight and 1 inorganic refractory powder with a particle size of 0.5 to 400μ
00 to 100,000 parts by weight of a highly insulating inorganic composition.