JP2002275389A - Amorphous silica particle having increased oil- absorption, producing method and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new structure of amorphous silica particle which has a constant particle size, generates no fine-grain, is excellent in delustering function and antiblocking effect, has little tendency to abrasion, and is excellent in scratch resistance and graze resistance. SOLUTION: The amorphous silica particle comprises a dense amorphous silica and a bulky amorphous silica; having a pore volume of 2.6 mL/g or more in respect to a pore having a pore diameter of 3,600 angstrom or less as measured by a mercury injection method; and having an oil absorption rate of 260 mL/100 g or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous silica particle having an increased oil absorption by combining a dense amorphous silica and a bulky amorphous silica, a method for producing the same, and a use thereof. The present invention relates to an amorphous silica particle having a dual structure of a dense amorphous silica core and a bulky amorphous silica shell, a method for producing the same, and a use as a matting agent for paint.

[0002]

2. Description of the Related Art For the purpose of lowering the gloss of the surface of a coating film, silica fine powder or the like has been conventionally incorporated into a coating material as a matting agent. Is formed, thereby reducing the gloss value.

As such a matting agent silica, conventionally used is a wet-process silica, that is, a wet-process silica obtained by neutralizing sodium silicate with an acid. Contains finely divided silica having a refractive index of greater than about 1.448 and a loss on ignition value of not more than 2%, obtained by subjecting it to high-temperature heat treatment at a high temperature of about 800 ° C. or more after wet production by a conventional method. A matte composition that features is described.

Japanese Patent Application Laid-Open No. 1-298014 discloses that silica obtained by a wet method has an average particle diameter of 1-20.
It describes a method for producing a matting agent for paints, which comprises pulverizing to a size of μm and then heat-treating at a temperature of 400 to 1000 ° C. for 30 to 120 minutes.

Japanese Patent Application Laid-Open No. 2-289670 discloses an average particle size in the range of at least 1.0 ml / g pore volume of 1 to 10 microns and a specific particle size distribution when dispersed in a coating excipient. A matting agent comprising an inorganic hydrogel is described.

Further, Japanese Patent Application Laid-Open No. 5-117548 discloses a matte coating composition characterized by containing fine silica powder and resin particles having a positive zeta potential and an average particle diameter of 0.01 to 5 μm. Has been described.

Further, JP-A-7-166091 discloses that the BET specific surface area is 30 to 150 m ² / g, the oil absorption is 120 to 280 ml / 100 g,
A matting agent for paint obtained by surface-treating wet-precipitated silica having a bulk specific gravity of 30 to 150 g / L and an average secondary particle size of 1.0 to 5.0 μm with polyethylene wax, wherein the polyethylene wax A matting agent for paint is described, wherein the amount of treatment is 4 to 12 parts by weight based on 100 parts by weight of the wet precipitated silica.

Japanese Patent Application Laid-Open No. H11-60 proposed by the present applicant
No. 231 has a double structure of a dense amorphous silica core and a bulky amorphous silica shell, has a volume-based median diameter in the range of 1 to 5 μm, and has a particle size of 0.1 to 5 μm. 5
Amorphous silica particles characterized in that the content of fine particles having a particle size of not more than 10 μm is 10% by volume or less. To produce gelled amorphous silica by neutralizing the gelled amorphous silica under conditions of pH 2 to 10, wet-grinding the gelled amorphous silica to be formed, and wet-milled gelled amorphous silica particles In the presence of, an aqueous solution of an alkali silicate and an aqueous solution of a mineral acid are neutralized under conditions of pH 5 to 9 to precipitate the precipitated amorphous silica particles on the surface of the gel amorphous silica particles. Is described.

[0009]

The silica fine powder conventionally used as a matting agent has a fine primary particle size, but consists of irregular secondary particles in which these primary particles are aggregated. There is a problem that the particle shape is indefinite, the particle size distribution is wide and uneven, and it is difficult to control the dispersed particle size when dispersed in the paint.

That is, there is a certain limitation on the particle size of the silica particles which effectively acts to reduce the gloss by forming irregularities on the surface of the coating film. Particles exceeding this effective particle size do not effectively contribute to the reduction and form particles on the surface of the coating film, which has the disadvantage of impairing the appearance and surface characteristics of the coating film. Moreover, even if the known silica-based matting agent can reduce the content of particles larger than the effective particle size by pulverization or classification, etc.,
As a result, the content of particles having a diameter smaller than the effective particle diameter increases, which causes the following disadvantages.

First, since the content of particles having an effective particle size useful for reducing the surface gloss is small, the amount of the silica-based matting agent per coating material must be increased, and the cost is required. Is also troublesome. In addition, when particles having a particle size smaller than the effective particle size are contained in the paint,
As a result, there is a problem that the viscosity of the coating increases and the coating workability decreases, and further, due to the presence of small-sized particles present in the coating, the hue of the coating becomes dull or the toughness of the coating increases. There is also a drawback that mechanical properties such as properties are reduced. Further, a coating film containing agglomerated particles having a small particle diameter has a large tendency to scratch the surface due to friction or the like.

Furthermore, known amorphous silica-based matting agents, even if they have a somewhat satisfactory particle size composition before compounding, tend to disintegrate due to shearing force when dispersed in a coating material. Integration), which makes it impossible to avoid the disadvantages mentioned above.

The invention of Japanese Patent Application Laid-Open No. H11-60231 proposed by the present applicant has a uniform particle size not only in the state of powder but also in the state of being blended in paint or resin. Significant as providing amorphous silica particles having a novel structure that is free of fine particles, has excellent matting and anti-blocking effects, has a low tendency to abrasion, and is excellent in scratch resistance or scratch resistance. However, the relationship between the blending amount of amorphous silica in paints and the like and the matting effect is still insufficient in that a relatively large amount of compounding is required to obtain the predetermined matting effect. Not satisfactory.

[0014] Accordingly, an object of the present invention is to provide a predetermined excellent matting effect with a relatively small amount of compounding, and to achieve a matting effect without impairing the smoothness of the coating film surface. And a method for producing the same. Another object of the present invention is to provide amorphous silica particles having a remarkably improved oil absorption and a method for producing the same.

[0015]

According to the present invention, the dense amorphous silica (A) and the bulky amorphous silica (B) have a weight ratio of 7: 3 to 4: 6. Amorphous silica particles are provided, wherein the silica particles have a pore volume of not more than 3,600 angstroms as determined by a mercury intrusion method and a pore volume of not less than 2.6 mL / g. In the amorphous silica particles of the present invention: Oil absorption (JIS K 5101) 260mL / 1
1.00 g or more; 2. having mesopores having a pore volume of 0.50 mL / g or more in a region of a pore radius of 40 to 100 angstroms determined by a mercury intrusion method; 3. Consisting of clusters of dense amorphous silica (A) and bulky amorphous silica (B); 4. having a double structure consisting of a core of dense amorphous silica (A) and a shell of bulky amorphous silica (B); It is preferred that the dense amorphous silica (A) is a gel amorphous silica particle and the bulky amorphous silica (B) is a sedimentation amorphous silica particle. According to the present invention, the pH of the aqueous alkali silicate solution and the aqueous mineral acid solution is adjusted to pH.
A step of producing a gel-process amorphous silica by neutralization under the conditions of 2 to 10; and a step of pH 5 to 9 of the aqueous alkali silicate solution and the aqueous solution of the mineral acid in the presence of the gel-process amorphous silica particles. And mixing the precipitated amorphous silica particles with the gel amorphous silica under neutralization under the following conditions. According to the present invention, further, a step of neutralizing an aqueous solution of an alkali silicate and an aqueous solution of a mineral acid under conditions of pH 2 to 10 and wet-milling to produce a gel-process amorphous silica; In the presence of the particles, an aqueous solution of alkali silicate and an aqueous solution of mineral acid are adjusted to pH 5
Neutralizing under the conditions of 9 to 9 to precipitate the precipitated amorphous silica particles as a shell on the surface of the gel amorphous silica core. The present invention provides a process for producing amorphous silica particles, wherein the process is carried out at a deposition rate at which the weight ratio of shell silica per unit is increased to 0.5 or less per hour. The present invention also provides a matting agent for paints, an antiblocking agent for films, a filler for ink jet recording paper, and a strike-through preventive for papermaking, comprising the above-mentioned amorphous silica particles. In the matting agent for paints of the present invention, 1 to 2 parts by weight per 100 parts by weight of the amorphous silica particles is used.
It is preferable that the surface is treated with 0 parts by weight of wax.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Amorphous silica particles] The amorphous silica particles of the present invention have a pore radius of 3 determined by a mercury intrusion method.
The pore volume of 600 Å or less is 2.6 mL /
g, especially in the range of 2.7 to 3.1 mL / g, whereby when used as a paint matting agent, a predetermined excellent matting effect can be obtained with a relatively small amount of compounding. At the same time, a matting effect can be exhibited without impairing the smoothness of the coating film surface. Further, the amorphous silica particles of the present invention have a double structure of a cluster or a dense amorphous silica core and a bulky amorphous silica shell as in the prior art described above. This double structure can be confirmed by observing the amorphous silica particles with a transmission electron microscope (see FIG. 1 of JP-A-11-60231).

According to page 142 of "Flow of paint and pigment dispersion" issued by Kyoritsu Shuppan Co., Ltd. on May 1, 1971,
The relationship between the physical properties of the coating film and the pigment volume concentration (PVC) is shown in FIG.
, The upper area where the pigment volume concentration (PVC) is low is a glossy area, the area where the pigment volume concentration (PVC) is intermediate is a semi-gloss area, The lower region where the pigment volume concentration (PVC) is high is a matted region. It is also closely related to the critical pigment volume concentration (CPVC) value as a surrogate characteristic of the size of the voids between pigment particles in the coating composition system. The CPVC value (calculated from the OA of the following equation (1)) is 2
Indicate the boundaries, or marginal regions, that separate the disparate states of a species. With PVC of CPVC or higher, there is a shortage of a binder that fills the space between the pigments in the coating film. Conversely, CPVC
In the following, the binder is present in an amount more than necessary to fill the space. On both sides of this boundary, the properties of the coating change rapidly.

Here, the pigment volume concentration (PVC) is a volume ratio of the pigment to the mixture of the pigment and the vehicle. Also, the critical pigment volume concentration (CPVC) is defined as a value of PVC that is necessary and sufficient for a binder to just fill voids between pigment particles in a dry coating film. CPVC indicates the maximum pigment concentration corresponding to the dispersion state of the system. CPVC is calculated by the following formula (1) (formula 1) OA = oil absorption (amount of linseed oil mL required to make 100 g of pigment a hard paste) ρp = density of pigment (g / cm ³ )

FIG. 1 shows that a certain amount of oil absorption (JIS K5
As for the pigment having 101), it can be seen that a larger PVC value has a matting effect. However, when comparing matting effects of pigments having different oil absorptions, CP
It is necessary to pay attention to the value of VC. By using a pigment having a small CPVC value, an excellent matting effect can be obtained with a relatively small amount of compounding. The oil absorption of the amorphous silica particles of the present invention is 260 mL / 100 g or more, and the value of CPVC in Examples described later is 13.2 to 14.6%. The amorphous silica of Comparative Example 4 had an oil absorption of 200 mL /
100 g and a CPVC value of 18.5%.

As already pointed out, the amorphous silica particles of the present invention have a feature that the pore volume with a pore radius of 3600 angstroms or less is 2.6 mL / g or more. It has the following characteristics.
First, the amorphous silica of the present invention has a pore volume of 0.50 mL / g or more, particularly 0.60 mL / g in a region of a pore radius of 40 to 100 Å determined by a mercury intrusion method.
It has the above mesopores. In addition, the pore radius 20
The pore volume from 0 to 1000 Angstroms is about 1.0
It is about mL. FIG. 2 shows the pore distribution of the amorphous silica particles of Example 1 and the amorphous silica particles of Comparative Examples 4 and 5 determined by the mercury intrusion method. The amorphous silica of the present invention (Example 1) has a pore volume of 0.73 mL / g when the pore radius is 40 to 100 Å, whereas the values of Comparative Examples 4 and 5 are 0%. .09mL
/ G and 0.43 mL / g. In the amorphous silica of the present invention, by having mesopores in the above range, a bulky particle structure is stably maintained, and sedimentation in the paint is also prevented. In other words, it is understood that the comparative examples 4 and 5 have a considerably dense sedimentation, while the bulky particle structure is maintained in the example 1, so that the degree of sedimentation is mild. Further, amorphous silica particles obtained by simply mixing amorphous silica obtained by a commercially available gel method and amorphous silica obtained by a precipitation method (Comparative Example 6) had pores determined by a mercury intrusion method. The pore volume with a radius of 3600 Å or less is 2.2 mL / g, the pore volume with a pore radius of 40 to 100 Å is 0.26 mL, and the oil absorption is 222 mL / 100 g. Compared with the porous silica particles, the matting properties, sedimentation stability and scratch resistance are all inferior.

The amorphous silica particles of the present invention have a double structure of a dense amorphous silica core and a bulky amorphous silica shell, as in the above-mentioned prior art. Is preferred. Dense amorphous silica is a component that increases the strength of the particles and prevents the collapse and powdering of the particles,
A component that improves transparency by improving the refractive index of particles. On the other hand, bulky amorphous silica is a component that contributes to the matting action and the antiblocking action, and also improves the wear resistance and the scratch resistance.

When the dense amorphous silica particles are incorporated alone into a paint or resin, satisfactory matting and anti-blocking effects are not exhibited, and there is a remarkable tendency to abrasion. The scratching tendency is remarkable (see Comparative Example 5 described later). On the other hand, when a bulky amorphous silica is incorporated into a paint or resin, although a certain degree of matting action and antiblocking action can be obtained, the viscosity of the paint and resin tends to increase, and the transparency tends to be poorer. (See Comparative Example 4 described later). This is because bulky amorphous silica particles cause the particles to collapse (disintegration).
This is considered to be caused by a decrease in the ratio of particles having a particle size effectively acting on the matting action and the anti-blocking action, and an increase in the viscosity of fine particles generated by disintegration.

On the other hand, the amorphous silica particles of the present invention in which the dense amorphous silica (A) and the bulky amorphous silica (B) are combined in a weight ratio of 7: 3 to 4: 6 are In addition to being excellent in matting and anti-blocking effects, it has a low tendency to wear, and is also excellent in scratch resistance or scratch resistance. In particular, in the case of a double particle structure in which dense amorphous silica is used as a core and bulky amorphous silica is used as a shell, not only in the state of powder but also in the state of being mixed in paint or resin Since the diameter is constant, no fine particles are generated, and the coating or resin composition containing the amorphous silica particles is excellent in transparency, and the effects such as giving a deep appearance can be obtained. (See Example 1).
The reason for this is that the bulky amorphous silica shell contributes to the improvement of the matting and anti-blocking effects, the reduction of the tendency to wear and the improvement of scratch resistance, and the dense amorphous silica core Prevents disintegration and powdering of the particles, maintains the particle size of the amorphous silica particles in the most convenient range for the expression of matting and anti-blocking effects, suppresses the increase in viscosity due to powdering, and It is thought that it contributed to the improvement.

In the amorphous silica particles of the present invention, it is also important that the volume-based median diameter is in the range of 1 to 5 μm and the content of fine particles having a particle diameter of 0.5 μm or less is 10% by volume or less. is there. That is, since the median diameter is within the above range, the matting action and the anti-blocking action can be maximized even with a small amount of compounding, and the compounding is performed by suppressing the content of fine particles below the above range. An increase in the viscosity of the paint or resin can be suppressed.

The amorphous silica particles of the present invention have, as powder properties, a BET specific surface area of 150 to 400 m ² / g. When the specific surface area is smaller than the above range, the transparency tends to decrease, while when the specific surface area is larger than the above range, the particle strength tends to increase, and when added to the resin, the abrasion tends to increase. .

In the amorphous silica particles of the present invention, the dense amorphous silica and the bulky amorphous silica are contained in a weight ratio of 7: 3 to 4: 6, particularly 6.5: 3.5 to 4. .5: 5.
The presence of a weight ratio of 5 is good on the balance of the performance described above. If the amount of dense amorphous silica is less than the above range, the tendency to powder increases and the transparency tends to decrease. Yes, on the other hand, if the amount of bulky amorphous silica is less than the above range, the matting action and the anti-blocking action are reduced,
Abrasion and the like tend to increase.

Further, in the amorphous silica particles of the present invention, the dense amorphous silica may be formed by gel method amorphous silica particles and the bulky amorphous silica may be formed by sedimentation method amorphous silica particles. Although it is desirable from the viewpoint of production, the amorphous silica particles of the present invention are not limited to those produced by this production method.

FIG. 3 shows that the amount of the amorphous silica particles of the present invention (Example 1) was changed and the amount of addition and the matting effect (60 ° Gloss
3 is a graph plotting the relationship between the amorphous silica particles of the present invention and the amorphous silica particles of the present invention (Comparative Example 5).
It is clear that the matte effect is exhibited with a smaller amount of addition than the precipitated amorphous silica (Comparative Example 4).

Next, FIG. 4 shows the relationship between the matting effect (60 ° Gloss) and the smoothness of the coating film blended in the paint by changing the amount of the amorphous silica particles of the present invention. It is a plot, the amorphous silica particles of the present invention
(Example 1) clearly shows a matte effect while maintaining smoothness, as compared with Comparative Example 7 having almost the same matte effect.

[Production of Amorphous Silica Particles 1] The amorphous silica particles of the present invention are obtained by neutralizing an aqueous solution of an alkali silicate and an aqueous solution of a mineral acid under conditions of pH 2 to 10 by gel method amorphous silica. And neutralizing the aqueous solution of alkali silicate and the aqueous solution of mineral acid under the condition of pH 5 to 9 in the presence of the amorphous silica particles by the gel method. Obtained from the step of mixing with amorphous silica. The amorphous silica particles obtained by this production method are composed of clusters. The cluster as referred to in the present invention refers to a cluster-like or chain-like particle structure.

In the production method of the present invention, it is preferable to carry out the production of the gel-processed amorphous silica particles at a temperature of 50 ° C. or lower in order to form gel-form silica having a uniform structure.

Further, the production of amorphous silica particles by the precipitation method
It is preferably carried out at a temperature of 0 to 100 ° C., thereby preventing the precipitation of free bulky amorphous silica, and producing amorphous silica particles having a matting effect, an anti-blocking effect, and excellent abrasion resistance. Production can be performed with good yield and reproducibility.

(Production of Gel Method Amorphous Silica) In the production of gel method amorphous silica, an aqueous solution of an alkali silicate and an aqueous solution of a mineral acid are subjected to a neutralization reaction at a pH of 2 to 10 to give a silica concentration of 2 to 10%. Produce silica hydrogel slurry directly.
Further, a silica hydrogel slurry produced via a silica hydrogel as described below can also be used.

The alkali silicate as a raw material is converted into alkali-soluble silica or potassium silicate, such as water glass, which is JIS-standardized as an industrial product, and easily reactive silica recovered from a clay raw material such as acid clay. An alkali silicate or the like obtained by reacting a metal hydroxide solution can be used. The SiO ₂ concentration in the alkali silicate aqueous solution is preferably in the range of 6 to 28% by weight, and SiO ₂ : M ₂ O
The molar ratio of (M is an alkali metal) is generally 2: 1
It is preferably in the range of from 4: 1 to 4: 1 and especially from 2.5: 1 to 3.5: 1.

As the mineral acid used for the neutralization reaction, hydrochloric acid, sulfuric acid, nitric acid and the like are generally used, and a mixed acid thereof can also be used. The concentration of the aqueous mineral acid solution is generally in the range from 5 to 75% by weight, in particular from 10 to 60% by weight.

The neutralization reaction by contacting both raw materials includes a method in which either raw material of both raw materials is added to the other solution with stirring, and a method in which both raw materials solutions are simultaneously contacted under certain conditions. . The neutralization temperature is not particularly limited, but is generally 50 ° C. or lower, and the pH at the end of neutralization is suitably in the range of 2 to 10.

By the neutralization, a silica hydrosol is formed. Generally, when the hydrosol is allowed to stand for 30 minutes or more, it is converted into a silica hydrogel having a SiO ₂ concentration of 5 to 30% by weight.

After the obtained silica hydrogel is washed with water, a heat treatment may be carried out, if necessary, for moisture control and pore control. The temperature of this heat treatment is 100 ~ 170 ℃
Is suitable, for example, in an autoclave.

Thereafter, coarse pulverization is performed so that the diameter is generally 20 to 100 μm, and the SiO ₂ concentration is 10 to 20% by weight.
To a silica hydrogel slurry.

(Preparation of Amorphous Silica Particles Consisting of Clusters) In the presence of the gel method amorphous silica particles thus obtained, an aqueous solution of an alkali silicate and an aqueous solution of a mineral acid are neutralized at a pH of 5 to 9. Then, the precipitated amorphous silica particles are mixed with the gel amorphous silica to obtain the amorphous silica particles of the present invention. At this time, the mixing of the gel amorphous silica and the precipitated amorphous silica particles is performed at a weight ratio of the precipitated amorphous silica particles per gel amorphous silica of 0.5 or less per hour. preferable. The amorphous silica particles obtained by this production method are composed of clusters, and are different from those obtained by simply mixing the gel method amorphous silica particles and the precipitation method amorphous silica particles.

[Production of Amorphous Silica Particles 2] The amorphous silica particles of the present invention are obtained by neutralizing an aqueous solution of an alkali silicate and an aqueous solution of a mineral acid under conditions of pH 2 to 10 and then wet-pulverizing the mixture to form a gel. A step of producing amorphous silica; and a step of neutralizing an aqueous solution of an alkali silicate and an aqueous solution of a mineral acid in the presence of gel method amorphous silica particles under conditions of pH 5 to 9 to precipitate amorphous silica particles. Is deposited as a shell on the surface of the gel-formed amorphous silica core. In the production method of the amorphous silica particles having a double structure, it is important to carry out at a deposition rate at which the weight ratio of shell silica to core silica increases by 0.5 or less per hour. The amorphous silica particles obtained by this production method have a double structure consisting of a core and a shell.

This production method is characterized in that seed (core) particles having a uniform particle size range are produced by subjecting a gel method amorphous silica hydrogel slurry to wet pulverization under high-speed shearing. For wet grinding, a friction inner plate mill known per se, for example, (Dyno mill manufactured by Willie A. Bakkofen) is preferably used, but if high-speed shearing is possible, other wet grinding machines may be used. You can also. In this case, it is important that the temperature of the slurry does not exceed 50 ° C. in order to reduce aggregation between particles.

The seed particles (silica hydrogel) thus obtained are adjusted to a silica hydrogel slurry having a SiO ₂ concentration of 2 to 10% by weight. By carrying out a neutralization reaction between the aqueous alkali silicate solution and the aqueous mineral acid solution in the range of pH 5 to 9 in the presence of the seed particles, a bulky amorphous silica shell is reliably formed on the surface of the seed particles. Can be formed.

In the production method of the present invention, it is preferable that the production of the gel-processed amorphous silica particles is carried out at a temperature of 50 ° C. or lower from the viewpoint of forming the gel-process silica having a uniform structure. Are excellent in various physical properties.

Further, the formation of amorphous silica particles by the precipitation method
It is preferably carried out at a temperature of 0 to 100 ° C., thereby preventing the precipitation of free bulky amorphous silica, and producing amorphous silica particles having a matting effect, an anti-blocking effect, and excellent abrasion resistance. Production can be performed with good yield and reproducibility.

Further, in the method of the present invention, there is provided a method for producing amorphous silica particles having a double structure, comprising the step of depositing the precipitated amorphous silica particles as a shell on the surface of the gel amorphous silica core. It is also important to carry out at a deposition rate which increases the weight ratio of shell silica per core silica to 0.5 or less per hour, especially 0.3 or less. At a rate higher than this deposition rate, the pore volume (mercury intrusion method) is small, and it is not possible to obtain highly oil-absorbing amorphous silica.

[Use] The amorphous silica particles of the present invention can be blended into a coating material known per se to form a matte coating composition.

As paints, oily paints, nitrocellulose paints, alkyd resin paints,
In addition to commonly known coatings such as aminoalkyd coatings, vinyl resin coatings, acrylic resin coatings, epoxy resin coatings, polyester resin coatings, chlorinated rubber coatings, rosin, ester gum, pentaresin, cumarone indene resin, phenol Resin, modified phenol resin, malein resin, alkyd resin, amino resin, vinyl resin, petroleum resin, epoxy resin, polyester resin, styrene resin, acrylic resin, silicone resin, rubber base Paints containing one or more resins, such as resins, chlorinated resins, urethane resins, polyamide resins, polyimide resins, fluorine resins, natural or synthetic lacquers, and the like.

The paint used may be any of a solution paint, an aqueous paint, an ultraviolet curable paint, a powder paint and the like, depending on the method of use. Particularly suitable.

The organic solvent for the solution type paint includes: aromatic hydrocarbon solvents such as toluene and xylene; aliphatic hydrocarbon solvents such as n-heptane, n-hexane and isoper; alicyclic hydrocarbon solvents such as cyclohexane. Hydrogen solvents; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; alcohol solvents such as ethanol, propanol, butanol and diacetone alcohol; ether solvents such as tetrahydrofuran and dioxane; cellosolve such as ethyl cellosolve and butyl cellosolve A solvent; an ester solvent such as ethyl acetate and butyl acetate; and one or more kinds of aprotic polar solvents such as dimethylformamide, dimethylacetamide, dimethylsulfoxide and the like can be used. The resin concentration in the raw material solution is generally 5 to 70% by weight, particularly 1%.
Suitably, it is in the range of 0 to 60% by weight.

As the aqueous coating, a self-emulsifying type or a surfactant emulsifying type coating is used in addition to an aqueous type coating. Examples of the resin of the water-based paint include an alkyd resin, a polyester resin, an acrylic resin, an epoxy resin, or a combination of two or more of these, which are water-soluble or self-emulsified in an aqueous medium. In a self-emulsifying resin, self-emulsifiability is imparted by neutralizing a carboxyl group with ammonia or amines, or by quaternizing the contained amine. Also, various latex resins are used. Generally, the resin concentration is 1
Suitably, it is in the range of 0 to 70% by weight, especially 20 to 60% by weight.

As the ultraviolet (UV) curable paint, a high solid resin such as a UV curable acrylic resin, epoxy resin, vinyl urethane resin, acrylic urethane resin, polyester resin or the like is used alone or in combination of two or more. You.

Examples of powder coatings include thermoplastic resins such as polyamide, polyester, acrylic resin, olefin resin, cellulose derivative, polyether, and vinyl chloride resin, as well as epoxy resin, epoxy / novolak resin, isocyanate or epoxy-curable polyester resin. And the like.

The surface of the amorphous silica particles used in the present invention is made of an inorganic oxide such as titanium oxide, silicon oxide, zirconium oxide, zinc oxide, barium oxide, magnesium oxide, calcium oxide; silane, titanium or It can be coated or surface-treated with a zirconium-based coupling agent.

The amorphous silica may be coated with a metal soap, a resin acid soap, a coating of various resins or waxes or the like, if desired. In particular, treatment with an olefin resin wax such as polyethylene wax, oxidized polyethylene wax, and acid-modified polyethylene wax, or a wax such as animal or plant wax or mineral wax is effective in increasing matting effect and improving scratch resistance. This coating treatment can be easily carried out by adding an aqueous emulsion of wax to the washed amorphous silica cake and mixing. Amorphous silica particles 100
It is preferable that the surface is treated with 1 to 20 parts by weight of wax per part by weight.

In the present invention, the above-mentioned amorphous silica particles may be used alone as a matting agent, or may be used in combination with other fillers or pigments in the formulation of paint. As inorganic components used in combination, alumina, Attapal guide,
Kaolin, carbon black, graphite, finely divided silica, calcium silicate, diatomaceous earth, magnesium oxide, magnesium hydroxide, aluminum hydroxide, slate powder, sericite, flint, calcium carbonate, talc, feldspar powder, molybdenum disulfide, barite , Vermiculite, whiting, mica, pyroxene clay, gypsum, silicon carbide, zircon, glass beads, shirasu balloon, asbestos, glass fiber, carbon fiber, rock wool, slag wool, boron watermelon, stainless steel fiber, titanium white, zinc Hana, Bengala, iron black, yellow iron oxide,
Examples include zeolite, hydrotalcite, lithium, aluminum, carbonate, titanium yellow, chromium oxide green, ultramarine, navy blue and the like.

The amorphous silica particles of the present invention are also useful as fillers for blending thermoplastic resins, thermosetting resins or various rubbers, especially as antiblocking agents.

As the thermoplastic resin to be blended as the anti-blocking agent, olefin resins are suitable, especially low-, medium- or high-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, or these. Ethylene to α-
Polypropylene-based copolymer which is a copolymer with olefin, linear low-density polyethylene, ethylene-propylene copolymer, polybutene-1, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, ethylene- Propylene-butene-1 copolymer, ethylene-vinyl acetate copolymer, ion-crosslinked olefin copolymer (ionomer), ethylene-acrylate copolymer, and the like. These may be used alone or as a blend of two or more. It can also be used in the form of objects. The amorphous silica particles of the present invention are useful as an anti-blocking agent for an olefin-based resin film produced using a metallocene catalyst, and can eliminate the coloring tendency observed in conventional anti-blocking agents.

Of course, the antiblocking agent of the present invention
It can be blended with other resin films known per se, for example, nylon 6, nylon 6-6, nylon 6
10, polyamides such as nylon 11, nylon 12, thermoplastic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polysulfone, vinyl chloride resin, vinylidene chloride resin,
It can also be blended with a vinyl fluoride resin or the like.

When used as an anti-blocking agent, the amorphous silica particles are used in an amount of 0.005 to 10 parts by weight, preferably 0.05 to 3.0 parts by weight, more preferably 100 to 100 parts by weight of the thermoplastic resin. 0.005 to 1.
It is preferably used in an amount of 0 parts by weight.

Of course, the amorphous silica particles of the present invention can be blended with the above-mentioned thermoplastic resin, various rubbers, or thermosetting resins as a filler.

As the elastomer polymer for rubber, for example, nitrile-butadiene rubber (NBR), styrene-
Butadiene rubber (SBR), chloroprene rubber (C
R), polybutadiene (BR), polyisoprene (II
B), butyl rubber, natural rubber, ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (E
PDM), polyurethane, silicone rubber, acrylic rubber, etc .; thermoplastic elastomers such as styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, hydrogen Styrene-
And isoprene-styrene block copolymer.

Examples of the thermosetting resin include phenol-formaldehyde resin, furan-formaldehyde resin, xylene-formaldehyde resin, ketone-formaldehyde resin, urea-formaldehyde resin, melamine-formaldehyde resin, alkyd resin, unsaturated polyester resin, epoxy resin Resin, bismaleimide resin, triallyl cyanurate resin, thermosetting acrylic resin, silicone resin, or a combination of two or more of these.

In the case of use as a filler, it can be added in an amount of 0.5 to 20 parts by weight, particularly 2 to 10 parts by weight, per 100 parts by weight of the above-mentioned thermoplastic resin, thermosetting resin or elastomer.

In the case of use as a hygroscopic filler,
Depending on the purpose, it can be blended in an amount of 0.5 to 20 parts by weight, especially 2 to 10 parts by weight, per 100 parts by weight of the thermoplastic resin, thermosetting resin or elastomer.

Further, the amorphous silica of the present invention is useful as a paper coating agent, particularly as a filler for ink jet recording paper and a strike-through preventive for papermaking. Also, a chromatographic carrier,
It can be used for cosmetic bases, paints for electronic components, hygroscopic agents for electronic components, and other uses of amorphous silica.

[0067]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the following examples. The physical properties and evaluation methods of the matting agent and the like used in the present invention are as follows.

(1) Particle size An aperture tube of 50 μm was obtained by a Coulter counter (TA-II type manufactured by Coulter Electronics).
m.

(2) Specific surface area (BET method) ASAP 2010 (V) manufactured by Micromeritics Co., Ltd.
3.0) and the specific surface area was measured by the BET method.

(3) Pore Volume (Mercury Intrusion Method) Using an Autopore 9220 manufactured by Micromeritics Co., Ltd., the pore distribution of the powder was measured by the mercury intrusion method, and the pore volume having a pore radius of 3600 angstroms or less was determined. Was.

(4) Matting effect test method Using a two-pack polyurethane paint (Kansai Paint Co., Ltd., ever-dried Retan PG80III Clear) as a coating film forming agent, mixing with an isocyanate curing agent at a ratio of 90:10. Then, 1 to 6 parts of a sample was added to 100 parts by weight of the mixture, and the mixture was dispersed at 2500 rpm for 5 minutes using a disper disperser, and then applied to a PET film using a bar coater # 14, and then cured at room temperature and applied. A film was prepared. Next, 60 ° Gloss (gloss (%)) was measured using a digital gloss meter GM-3D manufactured by Murakami Color Research Laboratory. Table 1
Shows the measured values when 2 parts of the sample were added.

(5) Smoothness test method The time required for the degree of reduced pressure to fall from 380 to 360 mmHg of the coated film obtained in (4) was measured using a Beck smoothness tester manufactured by Toyo Seiki.

(6) Test Method for Sedimentation in Resin Two-pack polyurethane resin (Normal dry type Retan Clear No. 2)
026 Kansai Paint) diluted with a special thinner
o.4 Adjust viscosity with Ford Cup. 100 g of this resin
And 2 g of the sample, and use a disper at 2500 rpm
Disperse at m for 10 minutes. Thereafter, the sample is placed in a 100 mL graduated colorimetric tube and allowed to stand. The sedimentation state was observed 30 days after standing, and the sedimentation property was evaluated as follows by shaking the colorimetric tube. Sedimentation (redispersibility) A: The sediment re-disperses fairly easily by gentle shaking. ：: The sediment easily re-dispersed by gentle shaking. Δ: The sediment re-dispersed due to strong shaking. X: The sediment does not redisperse even by strong shaking.

(7) Friction test (scratch resistance) Test piece 1 (3 × 3 cm) from the coated sheet obtained in (4)
Then, a test piece 2 (20 × 4 cm) is prepared, fixed on a glass plate with the coating of the test piece 2 facing upward, and placed so that the coating of the test piece 1 matches the test piece 2. At this time, a 900 g weight was placed on the test piece 1 and a load of 100 g was applied per 1 cm 2. Next, the test piece 1 was moved from one end of the test piece 2 to the other end, and the surface condition of the rubbed coated plate was observed. The number of times of friction (round trip /
The times) 5, 15 and 25 were visually observed as follows to evaluate the scratch resistance of the coating film. Evaluation by visual observation Evaluation rank Streak Mottled pattern 1 Slightly visible None 2 Clearly visible None 3 Clearly visible 30-70% of the whole 4 Clearly visible 70% or more of the whole

Example 1 (First Step) 86 kg of No. 3 sodium silicate (SiO ₂ concentration: 22%) and 253 kg of water were placed in a 500 L stainless steel container.
After the addition, the temperature was raised to 35 ° C. while stirring. After the temperature was raised, sulfuric acid was added to the mixture until the pH reached 2.5, to obtain a gel amorphous silica slurry. After completion of the pouring, aging was performed for 5 hours. After the completion of ripening, wet pulverization was performed with a mycolloider. (Second step) the first gel method from Step amorphous silica slurry 60kg weighed a (SiO ₂ minutes 3 kg) in a stainless steel vessel 150L, is heated to stir under 85 ° C.. After the temperature was raised, the No. 3 sodium silicate diluted to a silica concentration of 13% and 7
% Sulfuric acid was simultaneously poured so as to have a pH of 7.5, thereby precipitating amorphous silica. At this time, the use amount of No. 3 sodium silicate was 20.8 kg, and the flow rate was 0.08 L / min (added for 4 hours). After aging, sulfuric acid was added to adjust the pH to 3.5.
Was adjusted. After the pH was adjusted, filtration and washing were performed to obtain a cake. Thereafter, the filter cake was dried, pulverized and classified to obtain amorphous silica particles having a double structure. Table 1 shows the physical property values and evaluation results of the obtained powder.

(Example 2) In the second step of Example 1, the amount of sodium silicate used was 10.4 kg and the flow rate was 0.0
The procedure was performed in the same manner as in Example 1 except that the flow rate was set to 8 L / min. Table 1 shows the physical property values and evaluation results of the obtained powder.

Example 3 In the second step of Example 1, the amount of sodium silicate No. 3 used was 15.2 kg and the flow rate was 0.0
The procedure was performed in the same manner as in Example 1 except that the flow rate was set to 8 L / min. Table 1 shows the physical property values and evaluation results of the obtained powder.

Example 4 In the second step of Example 1, the amount of No. 3 sodium silicate used was 25.6 kg and the flow rate was 0.0
The procedure was performed in the same manner as in Example 1 except that the flow rate was set to 8 L / min. Table 1 shows the physical property values and evaluation results of the obtained powder.

(Example 5) In the second step of Example 1, the amount of sodium silicate used was 30.7 kg and the flow rate was 0.0
The procedure was performed in the same manner as in Example 1 except that the flow rate was set to 8 L / min. Table 1 shows the physical property values and evaluation results of the obtained powder.

(Example 6) In a first step of Example 1, 60 kg of a slurry of a gel method amorphous silica (3 kg of SiO ₂ ) obtained without performing wet pulverization was weighed into a 150 L stainless steel container and stirred. The temperature is raised to 85 ° C below. After the temperature rise,
No. 3 sodium silicate diluted to a silica concentration of 13% and 7% sulfuric acid were simultaneously poured so as to have a pH of 7.5, and the precipitated amorphous silica and the gel amorphous silica were mixed to obtain amorphous silica. Particles were obtained. Table 1 shows the physical property values and evaluation results of the obtained powder.

Example 7 Example 7 was carried out in the same manner as in Example 1 except that the flow rate of sodium silicate No. 3 in the second step was changed to 0.16 L / min. Table 1 shows the physical property values and evaluation results of the obtained powder.

(Example 8) A low molecular weight polyethylene wax emulsion (HYTEC E-8237: manufactured by Toho Chemical Industry Co., Ltd.) was added to the cake after the filtration and washing in the second step of Example 1, and polypropylene was mixed with 100 parts by weight of silica. It was added so as to be 5 parts by weight in terms of wax solid content, to obtain surface-treated amorphous silica. Table 1 shows the physical property values and evaluation results of the obtained powder.

(Comparative Example 1) The procedure of Example 1 was repeated, except that the flow rate of sodium silicate No. 3 in the second step was changed to 0.65 L / min. Table 2 shows the physical property values and evaluation results of the obtained powder.

Comparative Example 2 The amount of sodium silicate 3 used in the second step of Example 1 was 39.2 kg, and the flow rate was 0.1.
The procedure was performed in the same manner as in Example 1 except that the flow rate was 5 L / min. Table 2 shows the physical property values and evaluation results of the obtained powder.

Comparative Example 3 The gel obtained in the first step of Example 1
60kg amorphous silica gel slurry (SiO ₂Minute 3
kg) separately from the reaction in the simultaneous injection method as in the second step.
Precipitated silica (SiO 2)₂2.7 kg) at 85 ° C
For 4 hours. Then, after aging in the same manner as in Example 1.
Was obtained to obtain amorphous silica. Physical properties of the obtained powder
Table 2 shows the values and evaluation results.

Comparative Example 4 Commercial product Mizukasil P-526 (manufactured by Mizusawa Chemical Industry Co., Ltd.), which is an amorphous silica precipitated by precipitation.
Was used to measure and evaluate physical properties. Table 2 shows the results.

(Comparative Example 5) Commercial product Mizukasil P-78A which is an amorphous silica gel method (manufactured by Mizusawa Chemical Industry Co., Ltd.)
Was used to measure and evaluate physical properties. Table 2 shows the results.

(Comparative Example 6) The silica powders of Comparative Example 4 and Comparative Example 5 were mixed at a weight ratio of 1: 1 and physical properties were measured and evaluated. Table 2 shows the results.

(Comparative Example 7) Physical properties were measured and evaluated using TS100 (manufactured by Degussa), which is a dry process amorphous silica. Table 2 shows the results.

[0090]

[Table 1] Note: (B) silica / (A) silica (weight ratio) is the weight ratio of bulky amorphous silica (B) to dense amorphous silica (A).
In the silica structure, ◎ indicates a double structure, and ○ indicates a cluster.
The pore volume 1 is a value of the pore volume having a pore radius of 3600 angstroms or less. The pore volume 2 is a value of the pore volume having a pore radius of 40 to 100 Å.

[0091]

[Table 2] Note: (B) silica / (A) silica (weight ratio) is the weight ratio of bulky amorphous silica (B) to dense amorphous silica (A).
In the silica structure, ◎ indicates a double structure, and ○ indicates a cluster.
The pore volume 1 is a value of the pore volume having a pore radius of 3600 angstroms or less. The pore volume 2 is a value of the pore volume having a pore radius of 40 to 100 Å.

[0092]

According to the present invention, the gel amorphous silica obtained by neutralizing an aqueous solution of an alkali silicate and an aqueous solution of a mineral acid under conditions of pH 2 to 10 is used as the gel amorphous silica. In the presence, an aqueous solution of an alkali silicate and an aqueous solution of a mineral acid having a pH of 5
By mixing with the precipitated amorphous silica by neutralization under the conditions of ~ 9, amorphous silica particles having a cluster consisting of dense gel amorphous silica and bulky precipitated amorphous silica are obtained. can get. Further, the gel-processed amorphous silica obtained by neutralizing the aqueous alkali silicate solution and the aqueous solution of mineral acid under the condition of pH 2 to 10 is wet-pulverized, and silicate is added in the presence of the gel-processed amorphous silica. Alkaline aqueous solution and mineral acid aqueous solution
In the step of precipitating amorphous silica by neutralization under the conditions of H5 to H9, the weight ratio of shell silica per core silica is increased at a deposition rate of 0.5 or less per hour, so that a dense silica is obtained. Amorphous silica particles having a double structure composed of gel-processed amorphous silica and bulky precipitated-process amorphous silica are obtained.

The amorphous silica particles having a cluster or double structure are amorphous silica particles having an appropriate silica particle strength and an extremely large pore volume and an oil absorption amount. Even when incorporated in a paint or resin, the particle size is constant, there is no generation of fine particles, the matting action and the antiblocking action are excellent, the abrasion resistance is small, and the scratch resistance or scratch resistance is improved. Is also excellent.

[Brief description of the drawings]

Fig. 1 Physical properties (gloss) and pigment volume concentration (PVC) of a coating film by "Flow of paint and pigment dispersion" issued by Kyoritsu Shuppan Co., Ltd.
Is the relationship.

FIG. 2 shows pore distributions of Example 1 and Comparative Examples 4 and 5 by a mercury intrusion method.

FIG. 3 shows the amounts of silica added and 60 in Example 1 and Comparative Examples 4 and 5.
゜ Gloss (gloss ratio (%)).

FIG. 4 shows 60 ° Gloss of Example 1 and Comparative Examples 4 and 7.
(Gloss ratio (%)) and smoothness.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI theme coat ゛ (reference) C09D 201/00 C09D 201/00 F term (reference) 4G072 AA25 AA41 BB13 BB15 GG01 GG03 HH19 HH22 JJ13 MM02 MM26 QQ06 QQ09 TT08 TT09 UU07 UU30 4J037 AA18 CA25 CC03 DD02 DD05 DD06 FF09 FF15 FF18 4J038 BA081 BA201 BA231 CC021 CD091 CG141 CM031 CR011 DA031 DA111 DB001 DD001 DD121 DG031 DH001 DJ021 DL031 HA446 NA01 4A018 EA0318A GA18

Claims (13)

[Claims] 1. Amorphous silica particles comprising a dense amorphous silica (A) and a bulky amorphous silica (B) in a weight ratio of 7: 3 to 4: 6, which are obtained by a mercury intrusion method. The obtained pore volume having a pore radius of 3600 angstroms or less is 2.
Amorphous silica particles characterized by being at least 6 mL / g. 2. The oil absorption (JIS K 5101) is 26.
The amount is at least 0 mL / 100 g.
Amorphous silica particles according to 1. 3. A pore radius of 40 determined by a mercury intrusion method.
Pore volume in the region of ~ 100 Å
The amorphous silica particles according to claim 1 or 2, having a mesopore of 0 mL / g or more. 4. An amorphous silica according to claim 1, wherein the amorphous silica particles comprise clusters of dense amorphous silica (A) and bulky amorphous silica (B). Silica particles. 5. The amorphous silica particles have a double structure comprising a core of dense amorphous silica (A) and a shell of bulky amorphous silica (B). Item 4. The amorphous silica particles according to items 1 to 3. 6. The method according to claim 1, wherein the dense amorphous silica (A) is a gel amorphous silica particle and the bulky amorphous silica (B) is a precipitated amorphous silica particle. Item 6. The amorphous silica particles according to item 4 or 5. 7. A step of neutralizing an aqueous solution of an alkali silicate and an aqueous solution of a mineral acid under conditions of pH 2 to 10 to produce gel-process amorphous silica, and in the presence of gel-process amorphous silica particles, Neutralizing the aqueous alkali silicate solution and the aqueous mineral acid solution under conditions of pH 5 to 9 and mixing the precipitated amorphous silica particles with the gel amorphous silica. For producing porous silica particles. 8. A step of neutralizing an aqueous solution of an alkali silicate and an aqueous solution of a mineral acid under conditions of pH 2 to 10 and wet-pulverizing to produce gel-process amorphous silica. Neutralizing the aqueous alkali silicate solution and the aqueous mineral acid solution in the presence of the solution under conditions of pH 5 to 9 to precipitate the precipitated amorphous silica particles as a shell on the surface of the gel amorphous silica core. A process for producing amorphous silica particles having a double structure, wherein the deposition is performed at a deposition rate at which the weight ratio of shell silica per core silica increases by 0.5 or less per hour. 9. A matting agent for paints comprising the amorphous silica particles according to claim 1. Description: 10. A matting agent for paints, which is surface-treated with 1 to 20 parts by weight of wax per 100 parts by weight of the amorphous silica particles according to claim 1. 11. An anti-blocking agent for a film, comprising the amorphous silica particles according to claim 1. Description: 12. A filler for ink jet recording paper comprising the amorphous silica particles according to claim 1. Description: 13. A strike-through preventive for papermaking, comprising the amorphous silica particles according to claim 1. Description: