JP2676784B2 - Binder - Google Patents

Description

TECHNICAL FIELD The present invention relates to a binder containing a novel silica sol. More specifically, the binder of the present invention is characterized by containing a stable sol composed of a novel elongated colloidal silica particle, a binder such as a ceramic fiber and a glass fiber, a binder of a mold, As binders for paints, adhesives, etc., surface treatment agents for glass, ceramics, metals, etc., binders for hard coat agents on the surface of substrates such as plastics, etc., and also for fibers or textile products,
It is also used as a surface treating agent for paper or the like, or as an impregnating agent for porous materials such as cement materials and gypsum materials.

(Prior Art) Silica sol generally has a property of forming an irreversible gel through a state of low viscosity to a state of high viscosity, and is known to be useful as a binder. However, conventionally known silica sol, the shape of the colloidal silica particles constituting it is spherical or a shape close to spherical, in the drawings attached to U.S. Pat. The type is indicated. One of them is a spherical one as shown above and is shown in FIG. 1 of the same drawing, and the other one is a non-spherical one in which the ratio of the major axis to the minor axis is about 2 to 3, and the lower section of FIG. Is shown in. The third is an irregular shape shown in the lower part of FIG. The third amorphous particle is formed from a three-dimensional network formed by linking smaller silica particles into a chain, as described in US Pat. No. 2,680,721. The fragment generated by the cutting is a result of particle growth, and when focusing on one particle, it has an elongated shape, but its elongation is not controlled to be in the same plane.

The shape of the colloidal silica particles in the sol is determined by the method for producing the sol, and according to the above-mentioned US Pat. No. 2,680,721 the spherical colloidal silica particles of the first type are produced. On the other hand, the manufacturing method of the invention of US Pat. No. 2,900,348 is so-called peptization method, and the colloidal silica particles of silica sol obtained by this method have the above-mentioned second or third type of shape. It is a thing.

(Problems to be Solved by the Invention) A sol composed of spherical colloidal silica having a particle diameter of 4 to 150 millimicrons has high stability and is used as a binder. Spherical shape may, for example, easily cause cracks in a coating formed from the silica sol-containing composition,
Also, when the composition containing the silica sol and the ceramic fiber is dried, the colloidal silica particles are transferred, which causes practical problems such as the powdery surface of the dried product. When such a problem occurs, it is carried out by adding another component to the silica sol for improvement,
Achieving sufficient improvement is not easy.

The silica sol obtained by the usual peptization method is not sufficiently stable, and in some cases, silica precipitation may occur during storage. The colloidal silica particles are non-spherical, but when this sol is used as a binder,
The problem also occurs when using the silica sol made of the spherical colloidal silica.

The present invention seeks to provide a binder exhibiting improved performance with a stable sol comprising a novel elongated colloidal silica particle as the binder component.

(Means for Solving the Problems) The binder of the present invention has a particle having a uniform thickness within a range of 5 to 20 millimicrons and extending in only one plane, and particles obtained by a dynamic light scattering method. It is characterized by containing a stable sol composed of elongated silica particles having a diameter of 40 to 300 mm.

The shape of the colloidal silica particles constituting the sol used in the binder of the present invention can be seen by a photograph taken with an electron microscope. A large number of colloidal silica particles present in this sol have an elongated shape in common, although the shape is limited to the same. Many of these colloidal silica particles are roughly classified into four types, that is, straight, bent, branched, and ring. Have difficulty. However, according to the photographs, the bent and branched ones have the highest fractions, and these types dominate. Focusing on one particle, the thickness is substantially uniform from one end to the other end of the particle. This substantially uniformity is derived from the production conditions of the sol, and the thickness also varies depending on the production conditions of the sol, and is determined according to production rules. The large number of colloidal silica particles in the sol made by a method is in the range of 5-20 millimicrons. However, the length of many colloidal silica particles in a sol made by a certain method is not constant. However, according to the photographs, the length is at least three times the thickness, and usually particles having a length of several to several tens of times occupy the majority.

The elongated colloidal silica particles constituting the sol used for the binder of the present invention have another feature. That is, this elongation is in the same plane. Even if it is bent,
Even if they are branched, they have elongation in the same plane, so all particles can lie in the same plane at a height corresponding to the thickness of these particles, as long as they do not overlap even if they have different shapes. . In the photograph of the colloidal silica particles of this sol taken by an electron microscope, it is usually difficult to distinguish one end and the other end of one particle because these elongated colloidal silica particles are overlapped, and therefore the length of the particle is small. Is difficult to measure. Further, in the photograph, it is difficult to determine whether or not the particles extend in the direction perpendicular to the plane, that is, in the three-dimensional direction. However, in the presence of this extension in the three-dimensional direction, the silica sol exhibits the properties peculiar to the presence of the three-dimensional network structure or a structure close to it, such as a remarkably high viscosity to non-fluidity, and is unstable, but The sol used as the binder is a stable medium viscosity liquid. Therefore, the colloidal silica particles constituting this sol have no elongation in the three-dimensional direction. The in-plane elongation, which is one of the features of the shape of the colloidal silica particles constituting the sol used in the binder of the present invention, does not mean that the elongation is purely mathematically exact. Rather three
This is meant by the fact that the silica sol having a dimensional network structure or a structure close to it does not exhibit the characteristics.

The size of the colloidal silica particles constituting the sol used for the binder of the present invention is not appropriate to represent it by the length estimated from the photograph, and the size of the particles corresponding to the length is used. It is appropriate to represent the measured value by the dynamic light scattering method that can be measured. When expressed by the value measured by this dynamic light scattering method, the size of the colloidal silica particles constituting the sol used in the binder of the present invention is 40 to 300 millimicrons.

The silica sol used in the binder of the present invention is usually 30
It contains not more than wt%, preferably 5 to 30 wt% SiO ₂ . The viscosity of the sol, but the higher value is high SiO ₂ content ratio in the sol, in the SiO ₂ 30 wt% or less, the number of RT
It is about cp to 500 cp. The sol is extremely stable and does not precipitate or thicken during storage. Further, in this sol, the medium may be any of water, an organic solvent, and a solution of water-soluble organic solvent and water.

As the aqueous silica sol whose medium is water, both acidic ones and alkaline ones can be used as the binder of the present invention. Further, the organosol whose medium is an organic solvent is easily obtained by substituting the water of an aqueous silica sol with an organic solvent by a conventional method, for example, a distillation substitution method, and this organosol is also used for the binder of the present invention. To be The organic solvent that is a medium of the organosilica sol may be a usual one that does not inhibit the activity of the colloidal silica particles, for example, alcohols such as methanol, ethanol, isopropanol and butanol,
Examples thereof include polyhydric alcohols such as ethylene glycol, dimethyl ether, ethers such as ethylene glycol monomethyl ether, hydrocarbon solvents such as toluene and xylene, dimethylacetamide, dimethylformamide, and the like. Both the above-mentioned aqueous sol and organosol,
It is active due to the silanol groups present on the surface of the colloidal silica particles and eventually irreversibly turns into a gel as the medium is removed.

The silica sol used for the binder of the present invention is water-soluble in the following steps (a), (b) and (c), and (a) in a colloidal aqueous solution of activated silicic acid containing ₂ to 6% by weight as SiO ₂ . An aqueous solution containing a calcium salt, a magnesium salt or a mixture thereof is used as CaO, MgO or both in a weight ratio to SiO _{2 of the} above active silicic acid.
A step of adding and mixing 1500 to 8500 ppm, (b) an alkali metal hydroxide, an organic base or a silicate thereof is added to the aqueous solution obtained by the step (a) SiO ₂ / M ₂ O
(However, SiO ₂ represents the total amount of the silica component derived from the active silicic acid and the silica component of the silicate, and M represents the alkali metal atom or organic base molecule.) Molar ratio
And (c) adding the mixture obtained in the step (b) to 60-150.
SiO ₂ / M ₂ O by a method characterized by including the step of heating for 0.5 to 40 hours at ℃.
(However, M represents an alkali metal atom or a molecule of a nitrogen-containing organic base compound.) It is produced as an alkaline aqueous silica sol which is stabilized by an alkali having a molar ratio of about 20 to 200. A stable sol can be obtained by further removing excess anions from this sol, and a high-concentration sol can be obtained by concentrating. Further, if this is subjected to a cation exchange treatment, an acidic aqueous silica sol can be obtained, and an alkaline aqueous silica sol other than the above can be obtained by adding another alkali to this. From these acidic aqueous sols, aqueous sols comprising positively charged colloidal silica particles can be obtained by a usual method.

As the binder of the present invention, in addition to the above-mentioned new silica sol alone, a conventionally known binder and other optional concomitant components can be contained.

Examples of conventional binders used in combination include a sol composed of the spherical colloidal silica and the non-spherical silica sol obtained by a so-called peptization method, an alkali metal silicate, an alkyl silicate hydrolyzed liquid, an alumina sol, and other metal oxides. Examples include sol and the like. Examples of other components contained in the binder of the present invention in combination with the above novel silica sol include water-soluble resins and their aqueous solutions, resin emulsions, thickeners and defoaming agents which have been conventionally mixed in silica sol. , Surfactant, refractory powder, inorganic fiber powder,
Examples include metal powder, bentonite, pigments, coupling agents and the like.

The binder of the present invention has a variety of uses. For example,
Binder for molding used for casting metal, binder for refractory molding, binder for catalyst carrier,
Binders for adsorbents, binders used for making molded bodies or mats of glass fibers, ceramic fibers, sheets, etc., inorganic paints, heat resistant paints, anticorrosion paints, binders for inorganic-organic composite paints, inorganic adhesives, heat resistant It is used as a binder for adhesives, inorganic-organic composite adhesives, and the like. These paints, adhesives and the like are used for various base materials such as glass, ceramics, metals, plastics, wood, fibers,
It can be applied to the surface of paper or the like. The binder of the present invention is used as a treatment agent for fibers, textile products, paper, wood, etc., or as a surface treatment agent for performing impregnation treatment from the surface of a porous hardened body such as concrete, mortar, cement, gypsum, and clay. Alternatively, it can also be used as a sealing agent for castings.

(Operation) The binder of the present invention contains colloidal silica particles derived from the silica sol contained therein. Since the colloidal silica particles have an active silanol group on the surface thereof, the binder of the present invention finally changes into a gel when water, an organic solvent, etc. are removed from the binder by, for example, drying.
In addition, the particles are attached, adsorbed or chemically bonded to various solid surfaces as described above depending on the activity of the surface of the colloidal silica particles. The colloidal silica particles contained in the binder of the present invention are elongated particles having an extension only in one plane as described above. The diameter is in the range of 5 to 20 millimicrons and is almost uniform, and the particle diameter by dynamic light scattering method corresponding to the length is 40
~ 300 millimicrons. The novel or improved performance of the binder of the present invention is due to the special shape of the colloidal silica particles.

For example, in the drying of the glass fiber felt, the ceramic fiber felt, etc. to which the binder of the present invention is added, when the solvent flows on the fiber surface accompanied by the evaporation of the solvent, the colloidal shape is caused by the elongated shape. The silica particles become difficult to move together with the solvent, and are almost fixed on the fiber surface, and the fixed colloidal silica particles capture another elongated colloidal silica particle, so that the inside of the felt is It is considered that the initially existing colloidal silica leads to the formation of a gel inside the felt, improves the bondability of the fibers inside the felt, and results in a decrease in dusting on the surface of the dried felt. The binder of the present invention is used in various applications as described above, but in any case, glass, ceramic,
Although it comes into contact with the surface of base materials such as hardened cementum, hardened gypsum, hardened clay, metal, plastic, wood, natural or synthetic fibers, and paper, and gelation occurs with drying, it is equivalent to the above In addition, it is considered that the non-mobility of the colloidal silica particles originally present on the surface of these base materials or between the surfaces of the base materials causes uniform gel formation, which also improves the binding property.

Furthermore, the good flexibility of dry coatings formed from paints containing the binder of the invention is due to the coalescence of the shaped particles when the elongated colloidal silica particles in the paint coalesce to form a gel. It is considered that this is because the formation of the layered structure is more likely to occur. This flexibility relaxes the stress generated in the coating film and imparts crack resistance to the coating film. Regarding the high smoothness of the coating film, it is considered that the colloidal silica particles having elongation only in one plane facilitate the formation of a hierarchical structure of coalescence, so that the smoothness of the resulting gel is enhanced.

Even if the colloidal silica particles have elongation only in one plane, their particle size is 300 as a measured value by the dynamic light scattering method.
When it is larger than millimicron, silica sol composed of such particles is not preferable because silica precipitation easily occurs during storage. On the other hand, when the particle size is 40 mm or less as the measured value, the effect due to the elongated shape becomes poor. It is difficult to produce both a stable sol in which the colloidal silica particles have a thickness of 5 millimicrons or less and a stable sol in which the colloidal silica particles have a diameter of 20 millimicrons or more, and a colloidal having a thickness of 5 to 20 millimicrons as a stable sol. Sols consisting of silica are preferred.

When a sol composed of colloidal silica particles having an elongated shape used in the present invention and a sol composed of colloidal silica particles having a conventional spherical shape or a shape close to a spherical shape are mixed as a binder and used as a binder, depending on the use of these materials, depending on the application. Gives a more preferred binder.

EXAMPLES Example 1 Commercially available JIS3 No. sodium water glass (SiO ₂ / Na ₂ O molar ratio
3.22, by adding water to the SiO ₂ content of 28.5 wt%), SiO ₂ concentration
A 3.6% by weight aqueous solution of sodium silicate was obtained. A column of cation exchange resin packed separately-prepared Amberlite 120B, by passing the aqueous solution of sodium silicate, SiO ₂ concentration of 3.56 wt%, pH2.81, aqueous colloidal solution of active silicic acid in the conductivity of 731μS / cm I got This solution contains Al ₂ O ₃
And 75 ppm of Fe ₂ O ₃ in total.

2000 g of the aqueous colloidal solution of active silicic acid was placed in a glass container, and then 8.0 g of a 10 wt% calcium chloride aqueous solution was added.
Was added at room temperature with stirring, and after 30 minutes, 12.0 g of a 10 wt% sodium hydroxide aqueous solution was further added at room temperature with stirring.
The resulting mixture has a pH of 7.6 and an SiO ₂ / Na ₂ O molar ratio of 80.

Then, the mixed solution was charged into a stainless steel autoclave, heated at 130 ° C. for 6 hours with stirring, and then cooled to take out the content. The resulting liquid is a silica sol, SiO ₂
Containing 3.52 wt%, SiO ₂ / Na ₂ O titration molar ratio 101 and pH
It was 9.64, and CaO was contained at 5400 ppm by weight with respect to SiO ₂ , and free calcium ions were not detected.

Next, when the silica sol was concentrated by an ultrafiltration device, a concentrated silica sol (A) having a SiO ₂ concentration of 21% by weight was obtained. This concentrated sol does not contain dissolved or free calcium ions as a result of analysis, and has a specific gravity of 1.136, pH 9.24, and a viscosity of 1
24cp (20 ℃), SiO ₂ / Na ₂ O titration molar ratio 126, CaO content
The content was 0.113% by weight, the chloride ion content was 0.019% by weight, the sulfate ion content was 0.0020% by weight, and the electrical conductivity was 2080 μS / cm. The colloidal silica particles of this sol (A) were elongated particles and had a thickness of 12 millimicrons when observed from an electron micrograph. The sol (A) had a colloidal silica particle diameter of 84.6 mm as measured by the dynamic light scattering method. Further, the colloidal silica particle size calculated from the BET method was 12 mm.

When this concentrated silica sol (A) was stored at 60 ° C. in a sealed state, no alteration was observed even after 1 month.

When this sol was applied to a glass plate and dried, a better film was formed than when a conventional sol was used.
This coating did not dissolve in water when contacted with water.

Separately, concentrated aqueous silica sols (E) and (F) were obtained in the same manner as in the above production method except that the heating temperature and time in the autoclave were changed. This aqueous sol (E) has a colloidal silica thickness of 10 mμ and a dynamic light scattering particle size of 150.
mμ, SiO ₂ concentration 15% by weight, aqueous sol (F) colloidal silica thickness 9 mμ, dynamic light scattering particle size 250 m
μ, SiO ₂ concentration was 8% by weight.

Example 2 The silica sol (A) having a silica concentration of 21.0% by weight obtained in Example 1 was diluted with pure water to a silica concentration of 16% by weight and passed through a column packed with a cation exchange resin to obtain an acidic silica sol having a silica concentration of 15.7% by weight. (B) was obtained.

The obtained sol (B) has a specific gravity of 1.092, pH of 2.20 and viscosity of 13c.
p, SiO ₂ 15.7% by weight, Na ₂ O 190ppm, CaO 185ppm, Cl 144pp
m, SO ₂ 16 ppm, conductivity 3,030 μS / cm, BET method particle size 12.0
The particle size was mμ and the particle size was 84.6 mμ by the dynamic light scattering method. This sol (B) was stable at room temperature for 3 months or more.

Example 3 800 g of the acidic silica sol (B) obtained in Example 2 was placed in a rotary vacuum concentrator, and the inside of this device had a vacuum degree of 650 to 720 Torr.
While maintaining the liquid temperature at 20-40 ℃, add anhydrous methanol 12,0
The water in the sol was replaced with methanol by adding 20 g over 14 hours and azeotropically removing water.

The obtained methanol silica sol (C) has a specific gravity of 0.876,
Viscosity 14.5cp, SiO ₂ content 14.3% by weight, H ₂ O content
1.0% by weight. This sol (C) was stable at room temperature for 3 months or more.

Example 4 The acidic silica sol (B) obtained in Example 2 was further treated with an anion exchange resin, and then water in the dispersion medium was replaced with ethyl cellosolve by a distillation displacement method to obtain ethyl cellosolve silica sol (D). It was This sol (D) had a specific gravity of 1.025, a viscosity of 28 c.p., 15.2% by weight of SiO ₂ and 0.3% by weight of water.

Example 5 100 g of the aqueous silica sol (A) obtained in Example 1 and a spherical aqueous silica sol (specific gravity 1.144, pH 9.69, viscosity 4.3 c.
p., SiO ₂ 21.9% by weight, SiO ₂ / Na ₂ O titration molar ratio 126, conductivity 2140 μS / cm, BET method particle size 11.0 mμ, dynamic light scattering method particle size 26.8 mμ) 100 g, and The obtained mixture sol was left at room temperature in a sealed state, but was stable for 6 months or more.

The mixture sol contains 50% by weight of the aqueous silica sol (A).
In addition to this, the above-mentioned aqueous silica sol (A) is contained in addition to 30
Also in the case of the mixed sol containing 70% by weight and the mixed sol containing 70% by weight, it is stable for 6 months or more at room temperature under the same sealed condition as above, and the conventional sol and this elongated silica sol are mixed at an arbitrary ratio. Indicates that it can be used.

Example 6 This example is an example in which a template was prepared using the aqueous silica sol (A) obtained in Example 1 as a binder.

1000 parts by weight of the above silica sol (A), 2900 parts by weight of zircon flour (# 350), 2 parts by weight of surfactant and 1 antifoaming agent
By mixing the parts by weight, a slurry for the first layer was prepared. A wax model was dipped in this slurry for coating, and zircon sand (# 80) was sanded and dried to form a first layer. Next, 3450 parts by weight of zircon flour (# 200), 2 parts by weight of a surfactant and 1 part by weight of an antifoaming agent were mixed with 1000 parts by weight of the above-mentioned silica sol, and the resulting slurry was dipped in a backup slurry to obtain a second coating. Then, the second layer was formed by sanding with high alumina sand having a particle size of 0.3 to 0.7 mm and drying. After that, the third to sixth layers were sequentially laminated by the same method. After that, the wax model was removed by heating in an autoclave and further baked at 1000 ° C. for 1 hour to form a shell mold. No crack was observed in the dried shell and the baked shell obtained above, and there were no abnormalities such as rough skin. The bending strength of the shell is 56 kg / cm ² in the raw form,
The firing type was 98 kg / cm ² , and the repeatability as a result of repeated tests was also good. When the obtained baking mold was poured with molten metal, a good mold product was obtained.

Comparative Example 1 Instead of the above silica sol (A), a commercially available spherical silica sol (specific gravity 1.210, pH 9.95, viscosity 3.5 cp, SiO ₂ 30.2% by weight, BET method particle size 12.5 mμ, dynamic light scattering method particle size 23 mμ)
A slurry was prepared in the same manner as in Example 6 except that was used to prepare a shell mold. The resulting dried shell,
Generation of small cracks was observed in all of the shells after firing. The bending strength of the green type and the fired type is 48 kg / c each.
Although it was m ² and 89 kg / cm ² , the strength of the results of repeated tests varied considerably. Further, the obtained cast product had defects such as skin defects and cracks.

Example 7 This example is an example of an inorganic adhesive containing the binder of the present invention.

The above-mentioned aqueous silica sol (A) (500 g) is mixed with 100 g of 325-mesh pass fused alumina powder and 1500 g of fused alumina powder containing 90% of 200-250 mesh in a universal mixer for 30 minutes, and an inorganic adhesive containing the binder of the present invention. Was prepared. This adhesive had a viscosity of 4300 c.p. When this adhesive was filled in the gap between the ceramic seat of the small halogen lamp and the quartz glass tube with an automatic dispenser made by Takeshita Engineering Co., Ltd., the adhesive did not flow out from the bottom of the seat,
Moreover, it was confirmed that even if the filling was done from one place, it flowed all over the adhesive part and spilled around, and was extremely suitable as an adhesive for mass production automation. This lamp was dried at 90 ° C. for 30 minutes and then heated at 650 ° C. for 2 hours, and no abnormality was found in adhesion.

Comparative Example 2 An inorganic adhesive was prepared by adding the same amount of the same fused alumina as described above to 500 g of an aqueous silica sol composed of spherical particles having a SiO ₂ content of 20% by weight and a BET method particle size of 28 mμ, and mixing with a universal mixer for 30 minutes. This adhesive had a viscosity of 3900 c.p. When this adhesive was filled in the clearance between the ceramic seat of the small halogen lamp and the quartz glass tube in the same manner as described above, it flowed out a little from the bottom, and it was confirmed that it was not suitable for this application. To this adhesive was further added 55 g of 325 mesh pass fused alumina powder and kneaded for 15 minutes to prepare an inorganic adhesive having a viscosity of 4320 c.p. This adhesive was filled with the above-mentioned dispenser from one place in the same manner as in Example 7, but it was found that this adhesive could not wrap around the whole and was not suitable for such an application.
Good results were obtained because the inorganic adhesive prepared with the binder of the present invention imparted thixotropic physical properties due to its elongated grain shape.

Example 8 1800 g of the above aqueous silica sol (E) was added to an omni mixer, 500 g of potassium titanate fiber and 300 g of aluminosilicate fiber bulk were further added thereto, and after kneading for 10 minutes, further kneading,
120g of 10% sulphate solution was added and kneaded for 5 minutes to prepare a slurry, and a suction filter was used to make a board of about 4m / m thickness in a wet state on a metal mesh, which was then dried at 70 ° C for 3 hours to withstand heat. A porous inorganic fiber board was prepared.

During board preparation, this board is strongly entangled with the fibers due to the strong cohesive effect of mulberry soil,
The bending strength of S A5424 was 52 kg / cm ² .

Comparative Example 3 A board was prepared in the same manner as in Example 8 except that the silica sol used in Comparative Example 2 was replaced by 1800 g of the silica sol used in Comparative Example 2, and the strength was measured to be 38 kg / cm ^2. It is about 20% lower than the strength of the board obtained in Example 8.

Example 9 150 g of silica sol (A) used in Example 6 and 50 g of water
15 g of short fiber cotton-like silica-alumina ceramics fiber was added and mixed uniformly, and the mixture was transferred to a funnel having a diameter of 6 cm, and the excess liquid was filtered off under a press. The obtained water-containing molding water was taken out from the funnel and dried with hot air at 150 ° C. to obtain a plate-shaped inorganic fiber molding having a thickness of 2 cm. This molded body was cut along a diameter line using a cutter, and when a coloring agent solution for colloidal silica was applied to the cut surface, the entire cut surface was colored uniformly, and the distribution of colloidal silica as a binder was uniform. It was confirmed. Also, the tensile strength of the molded body was as large as 0.35 kg / cm ² . Furthermore, there was little dusting and it was good. This example shows that a molded body with less migration and high strength can be obtained by using the above-mentioned elongated silica sol.

Comparative Example 4 Instead of the elongated silica sol, a commercially available spherical aqueous silica sol (SiO ₂ 20.2% by weight, specific gravity 1.129, pH 9.85, viscosity 2.8 cp, BET method particle size 12.5 mμ, dynamic light scattering method particle size 2
A molded body was prepared in the same manner as in Example 9 except that 2 mμ) was used. As a result, the silica sol, which is a binder, has a low fixing rate and a low tensile strength of 0.2 kg / cm ^2, and the cross-section of the molded body shows an uneven distribution of silica, with a small amount of silica in the center and a large migration. ing. Also, powdering was remarkable.

Example 10 300 g of the above aqueous silica sol (F) with a high-speed stirrer 1
110 g of talc powder, 5 g of potassium titanate fiber and 25 g of ground glass powder are added in that order with stirring, and the mixture is stirred for a further 30 minutes and thoroughly dispersed to form a completely inorganic flexible coating agent. Was prepared.

About 400 g / m ^{2 of} this cord is coated from the end of the heat-resistant wire covered with glass fiber to a length of 100 m / m, and 100
It was dried at ° C for 1 hour. It was confirmed that this coating layer maintained strong adhesion and flexibility without peeling or powdering even in a 10-cycle bending test.

Comparative Example 5 The same talc powder, potassium titanate fiber, and ground glass powder as used in Example 10 was added to 300 g of an aqueous silica sol containing 12% by weight of SiO ₂ and composed of spherical particles having a BET method particle size of 15 m / m. Was added in the same amount to prepare a completely inorganic coating agent under the same conditions.

This coating agent was coated under the same conditions as in Example 10, and 110
After drying at 0 ° C for 1 hour, a bending test of 10 cycles was performed, and cracks were generated from 2 cycles, partial peeling was caused, and powdering was also caused, and insufficient flexibility and adhesion were observed.

Example 11 2 kg of methanol silica sol (C) obtained in Example 3
To a mixing tank equipped with a stirrer, 15g of bentonite powder, 3.5kg of 325 mesh 90% pass silica stone powder, 5.1kg of 325 mesh pass calcium carbonate powder, and 20g of perlite powder are added in sequence with stirring. A thick coating material for concrete wall of about 3200c.p. Was created. This coating material was an easy-to-use coating material in which there was almost no sedimentation and separation even after the stirring was stopped and the mixture was allowed to stand for one day. It is recognized that the binder of the present invention has a thickening and dispersing effect.

Comparative Example 6 A coating material was prepared under exactly the same conditions as in Example 11 using 2 kg of methanol silica sol composed of spherical particles having a particle diameter of 16 mμ by the BET method and containing 30% by weight of SiO ₂ . This coating material had a viscosity of about 3000 c.p., and when left to stand for 1 day, the silica stone powder was mainly separated into layers, and the lower layer was easily solidified, and was a difficult-to-use coating material. In order to make this coating material difficult to settle and separate as in Example 11, it was necessary to add and mix 17 g of sodium polyacrylate powder. The dry coating film of this coating material has a drawback that it has a bad odor and smoke when it is burnt with a flame, it turns into gray and the fire resistance is inferior.

Example 12 200 parts by weight of the silica sol (A) obtained in Example 1 was mixed with a resin emulsion (acrylic styrene copolymer resin emulsion, trade name Movinyl DM-6 manufactured by Hoechst Synthesis Co., Ltd.).
0) 50 parts by weight, 4 parts by weight of triethanolamine, 200 parts by weight of calcium carbonate, 500 parts by weight of silica sand and 50 parts by weight of titanium oxide were added, and the mixture was stirred and mixed with a Satake type stirrer for about 30 minutes to prepare an inorganic paint. The prepared paint was spray-coated on a slate plate and dried at room temperature for 1 day. The obtained coating film was evaluated for performance by a conventional method, and the results shown in Table 1 were obtained. The coating film using the elongated silica sol had no cracks and had good surface properties, water resistance, stain resistance, and the like. The stain resistance indicates that the antistatic property is good.

The adhesiveness was expressed by% of the number of residual stitches when a cross-cut was put on the coating film with a knife in a cornice shape and then instantaneously peeled off with cellophane tape.

Comparative Example 7 Instead of a silica sol having an elongated shape, a commercially available spherical aqueous silica sol (specific gravity 1.129, pH 9.85, viscosity 2.8 cp,
SiO ₂ 20% by weight, RET method particle size 12.5 mμ, dynamic light scattering method particle size 22 mμ) was used, and a paint having substantially the same composition as in Example 12 was prepared except that bentonite was used as a thickener. A coating film was formed in the same manner as 12 and evaluated. The results are shown in Table 1, and many cracks were generated in this coating film, so that the water resistance and surface property were poor. The ∘ mark means good, and the Δ mark means slightly bad.

According to the results of Example 12, the gel of elongated colloidal silica in the coating film shows that internal separation with the organic resin component does not occur, the elongated shape colloidal silica in a large amount of resin. It shows that a reinforced resin can be obtained when it is contained.

Example 13 Chromic anhydride was dissolved in water, saccharose was added thereto and heated to prepare a Cr ³⁺ / Cr ⁶⁺ molar ratio of 0.3, and a 4 wt% chromic acid solution as chromic acid was prepared. The acidic aqueous silica sol (B) 250 obtained in Example 2 was added to 1000 g of the chromic acid solution to prepare a treatment liquid. Separately, a plain steel plate (thickness 3.2 m
m, length 150 mm, width 150 mm), apply 1.5 g / m ² of the above treatment liquid on dry weight to it, and dry it in a hot air dryer at 150 ° C for 20 minutes, then immediately by hot press at 180 ° C for 10 minutes. Polyethylene was crimped to a thickness of 3 mm. The obtained steel sheet was subjected to a salt spray test, a hot salt water immersion test, and a cathodic peeling test by a conventional method to evaluate the corrosion resistance, and it showed excellent corrosion resistance.

Comparative Example 8 A polyethylene pressure-bonded steel plate was manufactured in the same manner as in Example 13, except that a commercially available spherical acidic aqueous silica sol (20% by weight of SiO ₂ , particle diameter by BET method: 12.5 mμ) was used in place of the acidic silica sol having an elongated shape. Was prepared and subjected to the same test, it was considerably inferior in the cathode peel test, and the rusting time was slightly shorter in the salt spray test.

Example 14 The silica sol (A) obtained in Example 1 was treated with a cation exchange resin to remove sodium ions, and then aqueous ammonia was added to prepare an ammonia stable aqueous silica sol. The obtained sol has a specific gravity of 1.129 and a pH of 9.4.
0, viscosity 130 c.p., SiO ₂ 20.2 wt% and NH ₃ 0.20%. To 100 parts by weight of an aqueous ethylene-acrylic acid copolymer resin emulsion (solid content 20% by weight), 20 parts by weight of the ammonia stable type silica sol having a slender shape was added and sufficiently stirred to prepare a paint. This paint was applied to a chromate-treated galvanized steel sheet and dried to form a film. The coating amount was 5 g / m ² (dry weight). Example 1
The results of the performance evaluation of the coatings tested in the same manner as 3 are shown in Table 2. The obtained coating film had good adhesion and corrosion resistance, and was particularly good with no occurrence of cracks during bending and drawing.

Comparative Example 9 Instead of the ammonia-stable elongated silica sol of Example 14, a commercially available spherical ammonia-stable aqueous silica sol (specific gravity 1.128, pH 9.30, viscosity 2.5 cp,
SiO ₂ 20.2% by weight, NH ₃ 0.20% by weight, BET method particle size 12.5 m
μ, particle size of 22 mμ by dynamic light scattering method)
A coating was formed in the same manner as in. The evaluation results of the coatings tested in the same manner as in Example 13 are shown in Table 2. However, the adhesion and corrosion resistance are not sufficient, and cracks are generated especially during bending and drawing, and partial peeling of the coating occurs. It was.

Example 15 Tohto Kasei Co., Ltd., a phenoxy resin commercially available under the trade name Phenothote YP-50 was dissolved in ethyl cellosolve, and a melamine resin was added as a crosslinking agent to prepare a solution having a resin content of 50% by weight. . Next, 65 parts by weight of the ethyl cellosolve sol (D) obtained in Example 4 was added to 100 parts by weight of this solution to prepare a coating material. This paint was applied to a chromate-treated galvanized steel sheet, and baked to dry to form a coating. The coating amount was 7 g / m ² (dry weight). The evaluation results of the film tested in the same manner as in Example 13 are shown in Table 2, and the adhesion, corrosion resistance and workability were all good. The ⊚ mark indicates that it is extremely good, the ○ mark indicates that it is not good, and the Δ mark indicates that it is not very good.

Comparative Example 10 An ethyl cellosolve silica sol was obtained by replacing water in a commercially available spherical aqueous silica sol with ethyl cellosolve by a distillation replacement method. This sol has a specific gravity of 1.140 and a viscosity.
The content was 4.3 cp, SiO ₂ 30.3% by weight, water content 0.3% by weight, BET method particle size 12.5 mμ, and dynamic light scattering method particle size 23 mμ.

Chromatization was performed in the same manner as in Example 15 except that the spherical silica sol (D) of Example 15 (65 parts by weight) was replaced by a mixture of the spherical ethyl cellosolve silica sol (33 parts by weight) and ethyl cellosolve (32 parts by weight). A coating was formed on the galvanized steel sheet and the performance was tested. As a result, as shown in Table 2, adhesion, corrosion resistance and the like were not sufficient as compared with Example 15, and cracks occurred in the bending workability test.

Example 16 A hydrolyzed solution of γ-glycidoxypropyltrimethoxysilane was prepared by adding 30 parts by weight of an aqueous hydrochloric acid solution to 100 parts by weight of γ-glycidoxypropyltrimethoxysilane and stirring the mixture. Then, 130 parts by weight of this hydrolyzed solution was added to the methanol silica sol (C) 56 obtained in Example 3.
A coating composition (hard coating agent) was obtained by adding 0 parts by weight, 50 parts by weight of isopropyl alcohol, 14 parts by weight of aluminum acetylacetone and 0.6 part by weight of a silicone-based surfactant, and thoroughly stirring them.

Separately, a plate of diethylene glycol bisallyl carbonate polymer marketed under the trade name CR-39 is prepared as a substrate, the above coating composition is applied thereto by a dipping method, left at room temperature, and then cured by heating at 110 ° C. By doing so, a film was formed on the substrate.

Then, abrasion resistance, adhesion, appearance, heat resistance, chemical resistance and the like were tested by a conventional method, and all showed excellent performance. A uniform coating was obtained without any cracks.

Comparative Example 11 Methanol silica sol having an elongated shape of Example 16
Instead of 560 parts by weight, spherical methanol silica sol (BET
Method particle size 12.5mμ, specific gravity 0.995, viscosity 2.0cp, SiO ₂ 30.5
% By weight, water content 1.4% by weight) and a coating composition was prepared in the same manner as in Example 16 except that a mixture of 260 parts by weight and 300 parts by weight of methanol was used. When the performance of the obtained coating film was tested in the same manner as in Example 16, the coating film was insufficient in adhesion, appearance, heat resistance and the like as compared with the results of Example 16.

Example 17 A non-waterproof liner paper was coated with a diluted solution of silica sol (A) obtained in Example 1 in water (SiO ₂ 5% by weight) by brush and dried at 105 ° C. for 10 minutes. ℃ relative humidity 50
%, The treated paper was obtained by leaving it in a constant temperature and humidity chamber overnight. The sliding angle of this treated paper was measured in the constant temperature and humidity chamber using a static friction coefficient measuring device. The silica coating amount of this treated paper was SiO ₂ 0.04 g / m ² , and the sliding angle was 35 °. Further, this treated paper showed a small tendency for the sliding angle to decrease even after repeating sliding on the same paper surface, and the sliding angle at the 10th measurement was 34.5 °. The silica did not fall off and there was little dusting. The sliding angle of the liner paper alone was 19 °. This test result shows that the silica sol having an elongated shape has a high fixing rate on paper and gives a good anti-slip effect.

Comparative Example 12 Instead of the elongated silica sol of Example 17, a commercially available spherical aqueous silica sol (BET method particle size 12.5 mμ, SiO ₂ 3
The test was conducted in the same manner as in Example 17 except that 0.2% by weight, pH 9.9) was used. The coating amount of silica was 0.04 g / m ² of SiO ₂ and the sliding angle was 29.5 °. The sliding angle at the 10th measurement is
At 28 °, the sliding angle tended to decrease as the number of measurements increased. In addition, there was a large amount of dust and the silica was often dropped off.

(Effect of the Invention) Conventional silica sol has been used as a binder in various applications, but the conventional silica sol is replaced with the elongated silica sol used in the binder of the present invention or mixed with a conventional silica sol and bonded. When used as an agent, various improvements can be achieved in various conventional applications. The elongated silica sol used in the present invention has the same SiO ₂ content as compared with the conventional spherical or nearly spherical silica sol.
With respect to the content, except that the viscosity is high, almost no difference is observed in appearance and properties, and the activity due to silanol groups on the silica particle surface is also the same. However, due to the unique elongated particle shape, a gel with a structure different from that of the conventional silica sol is formed when the sol forms a gel, and when the sol forms a gel on a solid surface, The colloidal silica particles of this sol exhibit immobility on the solid surface, thereby improving the binding property between the solid surface and the gel. And the sol composed of the elongated colloidal silica particles has good miscibility with various components similarly to the conventional silica sol. By mixing with silica sol, a binder composition having various performances can be obtained.

The dry coating film formed from the coating material containing the binder of the present invention has few pinholes, almost no cracks, has smoothness, and has softness that easily absorbs impact force,
It has good adhesion to the substrate, water retention, and antistatic properties. The baked coating film formed from the inorganic coating material containing the binder of the present invention exhibits good heat resistance. Further, the binder of the present invention has a slightly thixotropic property and is suitable as a binder for paints.

When making a mold for metal casting using the binder of the present invention, the drying gelation rate of the slurry of the binder and the refractory powder is fast, the mold production efficiency is improved, and the cracking occurs in the baking mold. Incidence rate decreases.

When a mat or sheet is prepared by using the binder of the present invention as a binder for glass fiber, ceramic fiber, etc.,
A mat or sheet having less dust on the surface after drying and high strength is obtained. The binder of the present invention is a natural fiber,
When it is used as a treatment agent for synthetic fibers and the like, an improved fiber or fiber product can be obtained because the adhesion to the fiber surface and the bondability between fine fibers are good. Even for porous materials such as concrete and gypsum, when impregnated from the surface thereof, the surface migration of the colloidal silica particles, which easily occurs during drying, is also small, so that a sufficiently improved surface layer can be obtained. Furthermore, the good miscibility of this sol with an organic resin brings about an improvement in the reinforcing effect, stain resistance, surface hardness, hydrophilicity, etc. of plastics, films, fibers, and other molded articles,
The same improvement can be achieved in the case of a resin composition obtained by adding this sol to a monomer before polymerization and then polymerizing it.

As already mentioned in the example in which the sol comprising the elongated colloidal silica used in the binder of the present invention is used as the binder, the composition containing this sol is
Compared with a conventional composition containing a spherical silica sol, it has a stronger property of thickening or gelling, and this sol can also be used for applications other than a binder by utilizing this property. For example,
Conventionally, spherical silica sol has been added to dilute sulfuric acid as an electrolytic solution of a colloidal battery, and the resulting gel prevents the electrolytic solution from flowing out of the battery even when the battery rolls over.
If the elongated silica sol is used in place of the spherical silica sol added to this battery, it can be further improved due to its high thickening or gelling performance, or the amount of silica sol to be added can be halved. it can.
Furthermore, spherical silica sol has been conventionally used for the purpose of thickening or gelling acids, for example, phosphoric acid, oxalic acid, butyric acid, chromic acid, etc., and using it in the form of paste or plastic. Improvements can be achieved by substituting shaped silica sols or the amount of silica sols used can be halved. As still another example, for the purpose of strengthening soft ground or soil, if the above-mentioned elongated silica sol is used as a gel-forming component of a so-called grout agent injected into the ground or soil, it has been conventionally used for this purpose. It is possible to achieve improvements in binding strength, water flow resistance, strength, etc., as compared with spherical silica sols.

The elongated silica sol brings various improvements when used in place of the spherical silica sol in the conventional spherical silica sol in addition to the above applications.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location D21H 19/38 D06M 11/12 (72) Inventor Keiko Tasaki 722, Tsuboi-cho, Funabashi-shi, Chiba 1 Nissan Central Research Institute of Chemical Industry Co., Ltd. Koji Amamiya

Claims (1)

(57) [Claims] 1. An elongated shape having a substantially uniform thickness within a range of 5 to 20 millimicrons, extending in only one plane, and having a particle size by dynamic light scattering method of 40 to 300 millimicrons. A binder containing a stable sol consisting of silica particles.