Powder comprising calcium titanium double oxide particles suitable as filler used in resin composition

Abstract

Provided are: a calcium titanium double oxide which can suppress an increase in viscosity when added to a resin, has a small elution amount of an electrolyte, and is suitable as a filler for a resin composition; and a method for producing the same. This powder comprises calcium titanium double oxide particles having an average primary particle diameter of more than 500 nm and 2,000 nm or less and a circularity of 0.75 or more. The powder has a boiled linseed oil absorption of 20.0 g / 100 g or less, has sodium and chlorine contents per 1.0 kg of the powder of 3,000 mg or less and 280 mg or less, respectively, and elution amounts of sodium, chlorine and calcium per 1.0 kg of the powder measured by the method described in the examples of 120 mg or less, 20 mg or less, and 420 mg or less, respectively. The powder can be produced by a method comprising mixing a titanium source, a calcium source and an alkali in a wet manner, heating the resultant mixture to 85-100°C inclusive under normal pressure, and subjecting the obtained reaction product to baking at 1,000°C or higher and an acid treatment.

Description

Powder consisting of calcium titanium double oxide particles suitable as a filler for use in resin compositions

[0001] The present invention relates to a powder made of calcium-titanium double oxide particles suitable as a filler for use in a resin composition, and a method for producing the same.

[0002] Resin compositions primarily composed of thermosetting resins and fillers have high moldability and can have a wide range of properties that can be varied by adjusting the types and amounts of resins, fillers, and other additives. Therefore, they are used in a variety of applications. Examples of applications of resin compositions include thermally conductive sheets, exterior materials for vehicles, and sealing materials for electrical and electronic components. When using resin compositions for various applications, it is necessary to select appropriate resins, fillers, and other additives according to the properties required for each application. In particular, fillers have a significant impact on the overall properties of the resin composition, so they must be selected according to the required properties, such as dielectric properties, thermal conductivity, and weather resistance.

[0003] For example, Japanese Patent Laid-Open Publication No. 2002-265797 (Patent Document 1) lists titanates such as barium titanate, strontium titanate, calcium titanate, and lead titanate as inorganic fillers with high dielectric constants, and describes their use in resin compositions. Calcium titanium double oxide has a particularly high dielectric constant among titanates, and further has electrical properties such as pyroelectricity and piezoelectricity, so it is sometimes used in electronic materials such as sealing materials for electric and electronic components and ceramic capacitors.

[0004] In recent years, resin compositions have come to be required to have high electrical properties, as exemplified by a higher dielectric constant, and studies have been conducted to further improve these properties. Patent Document 1 suggests the use of a filler with a lower sedimentation rate than the high dielectric constant filler in addition to the high dielectric constant filler, such as calcium titanate, in order to prevent filler sedimentation. However, as suggested in Patent Document 1, the use of a filler with a certain amount or more that does not contribute to improving electrical properties makes it difficult to achieve the high electrical properties of resin compositions that are currently required. A desirable method for improving the electrical properties of resin compositions is to increase the content of a filler with high electrical properties.

[0005] Generally, increasing the filler content increases the viscosity of the resin when added, which can deteriorate moldability and make production difficult using existing equipment, or can increase the number of defective products. A filler that does not increase the viscosity of the resin and can maintain moldability even when its content in a resin composition is increased is desired. In addition, when the filler content is increased, electrolytes eluted from the filler can impair electrical properties, such as insulation, or when used to seal electrical and electronic components, the electrodes to be sealed can corrode. Examples of electrolytes that cause these problems include ions of alkali metals or alkaline earth metals that constitute the filler. Furthermore, to increase the filler content in a resin composition, strict control of the particle size and particle size distribution of the filler is generally required. Therefore, fillers synthesized by a wet method, which is easy to control, tend to be used. However, ions of components derived from the acids and alkalis used in wet synthesis also cause the above-mentioned problems.

[0006] Japanese Patent Application Laid-Open Publication No. 2005-094068 (Patent Document 2) describes a method of using a dielectric ceramic powder with two or more particle size distribution peaks, modified to maintain fluidity even at high loadings, as a dielectric material to be mixed with a synthetic resin. However, adding a powder with two or more particle size distribution peaks results in complex changes in the properties of the resulting resin composition, leading to poor reproducibility. Even if an optimal, reproducible formulation is found, it is difficult to improve the properties if the desired properties change. Furthermore, Patent Document 2 does not mention electrolyte leaching. There is a need for a calcium-titanium double oxide suitable for use as a filler in resin compositions, which can suppress an increase in viscosity when added to the resin, maintaining moldability even when the content in the resin composition is increased, and which is resistant to electrolyte leaching and does not impair electrical properties.

[0007] JP 2002-265797 A JP 2005-094068 A

[0008] An object of the present invention is to provide a calcium-titanium double oxide suitable as a filler for resin compositions, which can suppress an increase in viscosity when added to a resin and which has a small amount of electrolyte elution, and a method for producing the same.

[0009] As a result of extensive research into the above-mentioned object, the inventors have discovered that by heating a slurry containing a titanium source, a calcium source, and an alkali, and then calcining and acid-treating the resulting reaction product, a powder of calcium-titanium double oxide particles having an average primary particle diameter of more than 500 nm but not exceeding 2000 nm and a particle circularity of 0.75 or greater can be obtained. This powder has a boiled linseed oil absorption of 20.0 g / 100 g or less, does not increase the viscosity of the resin when added as a filler to a resin composition, and exhibits low elution amounts of calcium, which constitutes the particles, and sodium and chlorine, which are representative electrolytes that tend to leach out of inorganic powders synthesized by a wet process. The present invention includes, but is not limited to, the following. Aspect 1: A powder made of calcium titanium double oxide particles having an average primary particle size in the range of more than 500 nm and not more than 2000 nm, and a circularity of the projected view of the primary particles of 0.75 or more, wherein the powder has a boiled linseed oil absorption of 20.0 g / 100 g or less, a sodium content of 3000 mg or less per 1.0 kg of powder and a chlorine content of 280 mg or less per 1.0 kg of powder, and an eluted sodium amount of 120 mg or less per 1.0 kg of powder, an eluted chlorine amount of 20 mg or less per 1.0 kg of powder, and an eluted calcium amount of 420 mg or less per 1.0 kg of powder, as measured by the method described in the Examples. Aspect 2: A powder made of calcium titanium double oxide particles having a BET specific surface area of ​​0.5 m 2 / g or more 10.0m 2 The powder according to aspect 1, wherein the true density is in the range of 3600 kg / m or less. 3 More than 4400kg / m 3The powder according to Aspect 1 or 2, wherein the number of combinations of perpendicularly intersecting planes per primary particle is 1.0 or less, as evaluated by the method described in the Examples using a scanning electron microscope photograph of the primary particles of the calcium titanium mixed oxide particles. Aspect 5 The powder according to any one of Aspects 1 to 4, wherein the ratio of the amount of calcium to the amount of titanium is 1.00 or more. Aspect 6 A method for producing the powder according to any one of Aspects 1 to 5, comprising: wet-mixing a titanium source, a calcium source, and an alkali, and heating the mixture at 85°C to 100°C under normal pressure to obtain a reaction product; and calcining the reaction product at 1000°C or more and treating it with an acid. Aspect 7 A resin composition comprising the powder according to any one of Aspects 1 to 5. Aspect 8 A sealing material comprising the powder according to any one of Aspects 1 to 5.

[0010] The calcium-titanium double oxide particles obtained by the present invention have a low boiled linseed oil absorption. The boiled linseed oil absorption corresponds to the ease of resin absorption when mixed with the resin. Powders with a higher boiled linseed oil absorption are more likely to absorb resin, resulting in lower dispersibility in resin and tending to increase the viscosity of the resin when added to it. Therefore, the boiled linseed oil absorption can be used as an indicator of the viscosity increase when the powder is added to a resin as a filler. Powders made of calcium-titanium double oxide particles with a low boiled linseed oil absorption obtained by the present invention can suppress the increase in viscosity of resins when added to resins, thereby less compromising the moldability of the resin composition. Furthermore, the powders made of calcium-titanium double oxide particles obtained by the present invention have controlled primary particle size and particle shape, making them suitable as fillers for resin compositions. Furthermore, the low elution of electrolytes (sodium, chlorine, and calcium) reduces the risk of loss of electrical properties in resin compositions or electrode corrosion due to the eluted electrolytes.

[0011] 1 is a transmission electron microscope image of the powder of Example 1.

[0012] (Powder composed of calcium titanium double oxide particles) The present invention relates to a powder composed of calcium titanium double oxide particles having an average primary particle diameter in the range of more than 500 nm but not more than 2000 nm and a circularity of 0.75 or more. In the present invention, the term "powder" refers to an aggregate of particles. The term "powder composed of calcium titanium double oxide particles" means that the majority of the particles constituting the powder are calcium titanium double oxide particles, or that the proportion of calcium titanium double oxide in the composition of each particle is high. Specifically, the powder has a proportion of calcium titanium double oxide particles of 900 g / kg or more, preferably 950 g / kg or more.

[0013] The calcium-titanium double oxide particles constituting the powder of the present invention have an average primary particle diameter greater than 500 nm, preferably 550 nm or greater, and more preferably 600 nm or greater. If the average primary particle diameter is greater than 500 nm, the particles are less likely to aggregate, and even if a large amount is added to the resin composition, an increase in the viscosity of the resin can be suppressed. Furthermore, the average primary particle diameter of the particles of the present invention is 2000 nm or less, preferably 1900 nm or less, and more preferably 1600 nm or less. If the average primary particle diameter is 2000 nm or less, a resin composition with a smooth surface can be obtained. The average primary particle diameter is evaluated by the method described below.

[0014] The calcium-titanium double oxide particles constituting the powder of the present invention have a circularity of 0.75 or more, preferably 0.78 or more, in the projection diagram of the primary particles. The greater the circularity of the projection diagram of the primary particles, the better the dispersibility in the resin, and even when a large amount is added to the resin composition, it becomes easier to suppress an increase in viscosity. There is no particular upper limit to the circularity of the particles, but theoretically the maximum is 1.00. The circularity of the projection diagram of the primary particles is evaluated by the method described below.

[0015] The powder of the present invention, which is made of calcium-titanium double oxide particles, has a boiled linseed oil absorption of 20.0 g / 100 g or less, more preferably 19.0 g / 100 g or less. The boiled linseed oil absorption of the powder corresponds to the ease of absorption by the resin when mixed with the resin. If the boiled linseed oil absorption is 20.0 g / 100 g or less, the absorption of resin components during the addition process is low, resulting in a small effect of inhibiting the behavior of the resin. Therefore, compared to adding the same mass of boiled linseed powder with a higher oil absorption, the fluidity of the resin is less inhibited, resulting in an effect of suppressing an increase in viscosity. Conversely, when the boiled linseed oil absorption is 20.0 g / 100 g or less, compared to using a boiled linseed powder with a higher oil absorption, the added amount of powder to the resin can be increased while maintaining the moldability of the resin composition. The lower limit of the boiled linseed oil absorption is not particularly limited, but a guideline is 10.0 g / 100 g or more. The oil absorption of boiled linseed is measured in accordance with JIS K 5101-13-2: 2004. The specific measurement method will be described later.

[0016] The powder of the present invention has a sodium content of 3000 mg or less per 1.0 kg of powder, a chlorine content of 280 mg or less per 1.0 kg of powder, and, further, the amount of sodium eluted into water (sodium elution amount) measured by the method described in the Examples is 120 mg or less per 1.0 kg of powder, and the amount of chlorine eluted into water (chlorine elution amount) is 20 mg or less per 1.0 kg of powder. Small sodium and chlorine contents facilitate suppression of elution amounts. On the other hand, while wet processes are generally suitable for synthesizing calcium-titanium mixed oxide particles with uniform particle size and particle size distribution, wet processes often require the use of reagents containing sodium and chlorine in the production process. In particular, it is difficult to reduce the sodium content, which is often present in the system when reacting a titanium source with a calcium source, to zero. While not limited thereto, the lower limit of the sodium content per 1.0 kg of powder is thought to be approximately 200 mg or more in practice. The lower limit of the chlorine content is not particularly limited, and it may be 0 mg per 1.0 kg of powder (below the detection limit). The calcium-titanium double oxide particles obtained by the present invention can suppress the amounts of sodium and chlorine eluted into water, even when they contain sodium and chlorine. If the amount of sodium elution is 120 mg or less per 1.0 kg of powder and the amount of chlorine elution is 20 mg or less per 1.0 kg of powder, electrical properties are unlikely to be impaired even when the powder is loaded into the resin in an increased amount. The amount of sodium elution is preferably 100 mg or less, more preferably 90 mg or less, and even more preferably 85 mg or less per 1.0 kg of powder, and the amount of chlorine elution is preferably 10 mg or less, more preferably 7 mg or less, and even more preferably 5 mg or less per 1.0 kg of powder. The amount of sodium elution is preferably 300 mmol / mol or less of the sodium content. If the amount of sodium elution is 300 mmol / mol or less of the sodium content, electrical properties are unlikely to be impaired by the sodium inevitably contained in the calcium-titanium double oxide particles of the present invention. More preferably, the amount of sodium elution is 250 mmol / mol or less of the sodium content.In this specification, the amount of eluted sodium (mmol) per 1 mol of sodium content is also referred to as the "ratio of eluted sodium" (unit: mmol / mol).

[0017] The powder of the present invention preferably has a low content of elements other than the sodium and chlorine mentioned above, excluding calcium, titanium, and oxygen, with the exception of substances contained in the coating layer on the particle surface described below.

[0018] In the powder of the present invention, the amount of calcium eluted into water (calcium elution amount), measured by the method described in the Examples, is 420 mg or less per 1.0 kg of powder. If the calcium elution amount is 420 mg or less per 1.0 kg of powder, electrical properties are less likely to be impaired even when the loading amount in the resin is increased. Furthermore, changes in electrical properties, including the dielectric constant, that occur due to a decrease in the calcium content in the calcium-titanium double oxide can be suppressed. The calcium elution amount is more preferably 400 mg or less, and even more preferably 300 mg or less, per 1.0 kg of powder.

[0019] The powder of the present invention has a BET specific surface area of ​​10.0 m 2 / g or less, and more preferably 8.0m 2 / g or less. BET specific surface area is 10.0 m 2 If the specific surface area is less than 0.5 m / g, the particles are less likely to aggregate, the dispersibility in the resin can be improved, and the fluidity of the resin is less likely to be impaired when the powder is added to the resin. 2 / g or more, more preferably 1.0m 2 A specific method for measuring the BET specific surface area will be described later.

[0020] The powder of the present invention has a true density of 3600 kg / m 3 It is preferable that the true density is 3600 kg / m or more. 3 If the true density is 3700 kg / m or more, the mass of the filler in the resin composition becomes large, and the electrical properties including the dielectric constant are easily improved. 3 The true density is 4400 kg / m3 It is preferably equal to or less than 4300 kg / m 3 More preferably, 4200 kg / m or less 3 The true density is 4400 kg / m or less. 3 If the density is below this, sedimentation of the filler in the resin can be suppressed and it becomes easier to disperse the filler uniformly. A specific method for measuring the true density will be described later.

[0021] The calcium-titanium mixed oxide particles constituting the powder of the present invention preferably have a number of combinations of perpendicularly intersecting planes per primary particle of 1.0 or less, as evaluated using a scanning electron microscope photograph by the method described in the Examples below. "Planes intersect perpendicularly" refers to a case in which the angle between two adjacent planes in a single primary particle in a scanning electron microscope photograph is 90°. For example, if three faces of a primary particle can be visually confirmed in a scanning electron microscope photograph and the particle is a perfect rectangular parallelepiped, the remaining invisible portion is also considered to be a perfect rectangular parallelepiped similar to the visible portion, and the number of combinations of perpendicularly intersecting planes is 12. Only primary particles of which 50% or more are visually visible are evaluated, and the invisible portion is considered to be similar to the visible portion. If a portion of the rectangular parallelepiped is chipped or rounded, causing the angle between the two faces to be no longer 90°, or if the number of faces itself is reduced, this number is reduced. If the observed shape is a hemisphere or semi-ellipsoid, the remaining invisible parts are also considered to be similar hemispheres or semi-ellipsoids, and the number of combinations of perpendicularly intersecting faces is counted as 0. Furthermore, when observing multiple primary particles constituting a powder, if the number of 90° angles formed by two adjacent faces is an average of 1.0 or less per primary particle, the number of combinations of perpendicularly intersecting faces is counted as 1.0 or less. When averaging, 100 or more primary particles are observed. If the number of perpendicularly intersecting faces is 1.0 or less per primary particle, mold wear during molding can be suppressed. Preferably, the average number is 0.8 or less per primary particle. For example, even if some particles in the powder have two or more combinations of perpendicularly intersecting faces, it is sufficient that the average number in the powder is 1.0 or less per particle.

[0022] In the powder of the present invention, the amount of calcium relative to the amount of titanium (Ca / Ti ratio) is preferably 1.00 or more. If the Ca / Ti ratio is 1.00 or more, unreacted substances are less likely to remain. Furthermore, from the viewpoint of suppressing excessive calcium elution, the upper limit of the Ca / Ti ratio is 1.50. A specific method for measuring the Ca / Ti ratio will be described later.

[0023] The powder of the present invention is not particularly limited, but when X90 / X10 is used as an index of particle size distribution, using the particle size (X10) corresponding to 10% of the volume-based cumulative particle size distribution and the particle size (X90) corresponding to 90%, it is preferable that the particle size distribution (X90 / X10) be 10.00 or less. More preferably, it is 7.00 or less. If the particle size distribution of the powder is 10.00 or less, clumps are less likely to occur in the resin and the reproducibility of properties is good. The lower limit of the particle size distribution is not particularly limited. It is most preferable that the particle size distribution be 1.00. A specific method for measuring the particle size distribution will be described later.

[0024] The aspect ratio of the primary particles of the calcium-titanium mixed oxide particles constituting the powder of the present invention is not particularly limited, but from the viewpoint of dispersibility in the resin, it is preferably 2.00 or less, and more preferably 1.80 or less. There is no particular limit on the lower limit. The aspect ratio is most preferably 1.00. A specific method for measuring the aspect ratio will be described later.

[0025] (Production Method) An example of a method for producing the powder of calcium-titanium double oxide particles of the present invention will be described below, but the method for producing the powder of the present invention is not limited to the following.

[0026] The calcium-titanium mixed oxide particles used in the present invention can be obtained by a method comprising wet-mixing a titanium source and a calcium source, heating a slurry containing the mixture of the titanium source and the calcium source and an alkali at normal pressure to react the titanium source and the calcium source, and then calcining the resulting reaction product at 1000°C or higher and treating it with an acid.

[0027] The titanium source is not particularly limited, but examples include titanium oxide, metatitanic acid, and sodium titanate. It is generally desirable for the titanium source to contain a large amount of titanium. When an acid-peptized metatitanic acid is used as the titanium source, the reaction tends to proceed uniformly. Furthermore, when an alkali metal salt, such as sodium titanate, is used, the amount of alkali added can be reduced or the addition step can be omitted. The optimal raw material is selected taking into consideration factors such as production facilities, desired properties, and cost.

[0028] When metatitanic acid or an alkali metal titanate obtained by treating metatitanic acid with an alkali is used as the titanium source, the diameter of the micelles formed by the metatitanic acid is preferably 45 nm or more. When the micelle diameter of the metatitanic acid used is 45 nm or more, calcium-titanium double oxide particles with a narrow particle size distribution are likely to be obtained. Although it is difficult to track the behavior of micelles during the reaction and therefore difficult to clarify the cause, it is believed that the suppression of aggregation in the steps leading up to the reaction and the presence of appropriate gaps between the micelles somehow contribute to the uniform progress of the reaction. The method for evaluating the micelle diameter of metatitanic acid will be described later.

[0029] The calcium source is not particularly limited, and examples thereof include calcium salts such as calcium hydroxide and calcium carbonate. It is generally desirable for the calcium source to contain a large amount of calcium and have a small content of substances that remain as impurities in the product. Calcium hydroxide is particularly preferred because it exhibits strong alkalinity when dissolved in water, allowing for a reduction in the amount of alkali added, and because it has a large amount of calcium per unit mass.

[0030] When producing the calcium titanium double oxide particles used in the present invention, it is preferable to wet mix the titanium source and calcium source. Wet mixing allows the calcium source and titanium source to be more uniformly mixed in the macroscopic region, and the evaporation of water further reduces the distance between the titanium source and calcium source. As a result, it is possible to obtain particles with an appropriately large average primary particle size. The calcium titanium double oxide particles obtained in this manner are also less likely to contain unreacted materials.

[0031] The titanium source and calcium source can be wet-mixed by any method. Mixing can be performed using devices such as a crusher, mixer, or mill, as needed. Generally, when the titanium source or calcium source needs to be pulverized, pulverization and mixing can be performed in the same process for efficiency. The procedure is not particularly limited as long as the pulverized titanium source and calcium source are ultimately mixed. Even if the mass ratio of titanium and calcium is appropriate, the desired calcium-titanium double oxide particles may not be obtained if the titanium source and calcium source are not mixed uniformly. Therefore, uniform mixing is desirable. It is preferable that the slurry after mixing is not only uniform from a macroscopic perspective, but also that the individual particles of the titanium source and calcium source are uniformly mixed. As a general guideline, this is easily achieved when the titanium source and calcium source are primarily composed of particles with a particle size of 300 nm or less.

[0032] When reacting a titanium source with a calcium source, the amount of calcium is preferably greater than 1.00, and more preferably 1.10 or greater, assuming that the amount of titanium is 1.00. Having a greater amount of calcium than titanium during the reaction can reduce the amount of unreacted titanium-containing materials, such as titanium dioxide. While not fully understood, it is believed that an excess of calcium relative to titanium during wet mixing facilitates contact of the individual titanium sources with the calcium source. On the other hand, if the amount of calcium source added is excessively large, the cost required to obtain the same mass of calcium-titanium double oxide increases. While this cannot be generalized, a calcium amount of 3.0 mol or less when the amount of titanium is 1.0 mol can be produced at low cost, and is more preferably 2.0 mol or less, and even more preferably 1.6 mol or less.

[0033] An alkali is added to a mixture of a titanium source and a calcium source to adjust the pH to 10.0 or more and 13.9 or less. By adjusting the pH to the above range, excessive dissolution of calcium is prevented, the mass ratio of titanium to calcium is maintained within an appropriate range, and calcium-titanium mixed oxide particles with a low content of unreacted substances can be obtained. The lower limit of the pH is preferably 10.5 or more, more preferably 11.0 or more, and even more preferably 12.0 or more. The upper limit is more preferably 13.8 or less.

[0034] The alkali used in the above procedure can be a compound containing an alkali metal or alkaline earth metal, such as sodium, potassium, or calcium. Hydroxides of these compounds are particularly preferred. Furthermore, considering solubility and ease of use, compounds containing sodium or potassium are more preferred. Two or more of these compounds may be used in combination. Sodium hydroxide is particularly preferred. One of the excellent features of this method is that calcium-titanium double oxide particles with a low amount of sodium elution can be obtained even when a sodium-containing compound, such as sodium hydroxide, is used during production. Furthermore, when calcium hydroxide is used as the calcium source, the aqueous solution exhibits strong alkalinity and itself functions as an alkali. Therefore, other alkalis may be used in addition to calcium hydroxide, or no alkalis other than calcium hydroxide may be added.

[0035] The mixture of titanium source, calcium source, and alkali is maintained at 85°C or higher under atmospheric pressure while stirring. The upper limit of the reaction temperature is not particularly limited, but the upper limit is essentially 100°C, which is the boiling point of water at atmospheric pressure. This method allows production by a reaction using water in air under atmospheric pressure. Another advantage of this method is that it does not require the use of equipment such as an autoclave or nitrogen substitution. The retention time varies depending on the scale, container shape, and concentration, but is generally 1.0 h or more and 30.0 h or less. The lower limit is more preferably 2.0 h or more, and even more preferably 4.0 h or more. The upper limit is more preferably 20.0 h or less.

[0036] After the retention period, the slurry is filtered and washed. Unless otherwise specified, ion-exchanged water is used for washing. Washing can be performed using known methods, such as a filter press, decantation, or a Nutsche method. While not particularly limited, washing is preferably performed until the electrical conductivity of the filtrate reaches 100 μS / cm or less. Although not universally applicable, washing until the electrical conductivity of the filtrate reaches 100 μS / cm or less facilitates reducing the content and elution amounts of sodium and chlorine, as well as the elution amount of calcium. Furthermore, the powder of calcium-titanium double oxide particles obtained by this method can be reduced in hardness after firing by the above-mentioned washing, enabling powder with a narrow particle size distribution to be obtained by pulverization. While the cause is unclear, it is thought that this is due to the removal of a certain amount of metal salts, such as sodium salts, which promote particle bonding during sintering. Generally, the greater the amount of ion-exchanged water used for washing and the greater the number of washing steps, the fewer impurities contained in the resulting calcium-titanium double oxide particles, but the higher the cost. The filtration and washing may be carried out after the slurry has been cooled after the retention period and subjected to the acid treatment described below.

[0037] In the production of the powder of calcium-titanium double oxide particles of the present invention, the calcination conditions are not particularly limited, but it is desirable to carry out the calcination in the atmosphere. The calcination temperature is preferably 1000°C or higher, more preferably 1025°C or higher. Calcination at 1000°C or higher eliminates particle irregularities and fine particles, and changes the particle surface composition, resulting in a calcium-titanium double oxide with low boiled linseed oil absorption and low electrolyte elution. While there is no particular upper limit, using temperatures that are too high increases the cost of producing calcium-titanium double oxide and increases restrictions on usable equipment and safety. Generally, as long as the calcination temperature does not exceed 1200°C, industrial production is easy, so a calcination temperature of 1200°C or lower is preferred. The calcination time is not particularly limited, but under the conditions examined in this invention, a calcination time of 1.0 hour or more is preferred, and 1.5 hours or more is more preferred from the viewpoint of completing the reaction.

[0038] The calcium-titanium double oxide particles obtained by this method may contain impurities, such as calcium compounds, on the particle surface after the reaction, so an acid treatment step is required in which the particles are washed with acid. Acid treatment removes impurities near the particle surface and eliminates surface irregularities. Acid treatment also removes sodium and calcium, which are easily released, thereby reducing the amount of these compounds leached out. While the type and pH of the acid are not particularly limited, mineral acids, such as hydrochloric acid, are preferred because they are inexpensive and do not tend to remain on the calcium-titanium double oxide particle surface. Water washing may be performed before acid washing. Furthermore, acid washing and water washing may be alternately repeated, for example, acid washing, water washing, and further acid washing. Acid washing may be performed before or after the calcination step, or multiple times. The order of filtration, washing, calcination, and acid treatment can be determined appropriately, taking into account factors such as cost.

[0039] The powder of the present invention may have an organic coating layer applied to at least a portion of the surface of the particles constituting the powder, for example, to improve fluidity in resins or the strength of resin compositions. Examples of organic coatings include treatments with silicone compounds such as dimethylpolysiloxane, hydrogen dimethicone, and polysiloxane; silane-based, aluminum-based, titanium-based, and zirconium-based coupling agents; fluorine compounds such as perfluoroalkyl phosphate compounds; hydrocarbons; lecithin; amino acids; polyethylene; wax; and metal soaps. Multiple combinations of these treatments may be performed, with no particular restriction on the order of treatment. The surface treatment method is not particularly limited, and any commonly used method may be used. For example, a coating layer can be formed by mixing a coating layer material with the powder and then heat-treating it. Because surface treatments can change electrical properties such as the dielectric constant, it is generally desirable that the mass of the coating layer be 50 g / kg or less of the powder.

[0040] In producing the powder of calcium-titanium mixed oxide particles of the present invention, the material obtained after calcination and drying may be pulverized as appropriate. The pulverization method is not particularly limited. Known methods, such as a ball mill, vibration mill, jet mill, or hammer mill, can be used without limitation. The pulverization method is determined based on particle size, the proportion of coarse particles in the pulverized product, cost, and other factors. Furthermore, a grinding aid may be added before pulverization to promote efficient pulverization. Examples of grinding aids include silicone compounds such as dimethylpolysiloxane, hydrogen dimethicone, and polysiloxane; silane-, aluminum-, titanium-, and zirconium-based coupling agents; fluorine compounds such as perfluoroalkyl phosphate compounds; hydrocarbons; lecithin; amino acids; polyethylene; wax; and metallic soaps. Multiple grinding aids may be used in combination, with no particular restriction on the order of addition. While the addition method is not particularly limited, a method in which the grinding aid is added while stirring the powder slurry is commonly used. Furthermore, classification or other operations may be performed after pulverization. These operations are not particularly limited.

[0041] (Applications) The powder of the present invention can be used as a filler to be incorporated into a resin composition, but is not limited thereto. For example, it can be used as a filler in a resin composition whose main component is a thermosetting resin. Resin compositions incorporating the powder of the present invention can be used for a variety of applications. The powder of the present invention has the characteristic of having a low boiled linseed oil absorption and being less likely to increase viscosity when incorporated into a resin composition, allowing for high loading into the resin composition. Therefore, it is particularly suitable for use in resin compositions that require the characteristics of the powder of the present invention, such as a high dielectric constant and heat resistance. For example, it is useful in applications requiring low thermal expansion, such as antenna substrates.

[0042] Furthermore, resin compositions incorporating the powder of the present invention can be used, for example, as encapsulants. The powder of the present invention can be particularly suitably used as a filler in resin compositions serving as encapsulants for electrical and electronic components, imparting high dielectric constants and heat resistance to the resin compositions. The powder of the present invention has a low boiled linseed oil absorption, and is therefore characterized by its low viscosity and low electrolyte elution when added to resins. Therefore, it is possible to achieve high loading in resin compositions, making it useful for obtaining resin compositions with higher performance or low thermal expansion. A typical example is its use as a resin encapsulant for semiconductors. The composition of the resin components in the resin encapsulant for semiconductors is not particularly limited. Furthermore, fillers other than the powder of the present invention, as well as other components such as flame retardants, may be contained in the resin composition.

[0043] The present invention will be described in more detail with reference to the following examples and comparative examples, which are provided for illustrative purposes only and are not intended to limit the scope of the invention.

[0044] In the stirring operations described in the examples and comparative examples, the rotation speed is appropriately adjusted to ensure that the entire liquid is mixed uniformly and that droplets do not scatter, taking into consideration properties related to the behavior of the liquid during stirring, such as the liquid volume, viscosity, and shape of the container. Furthermore, when the same effect can be obtained by using any company's product as long as it is a common commercially available product, such as hydrochloric acid, the names of the manufacturer and distributor are omitted.

[0045] [Micelle diameter of metatitanic acid, average primary particle diameter of calcium titanium double oxide particles] Measurements were made using a JEOL JEM-1400plus transmission electron microscope (hereinafter referred to as "TEM"). When measuring the micelle diameter, the metatitanic acid was observed in a peptized state. The observation magnification was 13,500x (transmission electron microscope observation magnification of 5,000x x print 2.7x). The longest lengths of 100 or more metatitanic acid micelles or calcium titanium double oxide primary particles were measured from the projected images, and the number average value was calculated to determine the micelle diameter of metatitanic acid and the average primary particle diameter of calcium titanium double oxide particles.

[0046] [BET Specific Surface Area] The BET specific surface area was measured by a BET single-point method using a Gemini (registered trademark) VII2390 manufactured by Micromeritics Instrument Co.

[0047] [Circularity and aspect ratio] The circularity and aspect ratio were evaluated using a two-dimensional projection of the primary particles of the calcium titanium mixed oxide particles. Specifically, the circularity and aspect ratio were calculated using an image obtained with a TEM at a magnification of 35,000 times (TEM observation magnification of 10,000 times x print 3.5 times) and the image analysis software ImageJ. The value obtained by dividing the major axis length of the projection by the minor axis length was taken as the aspect ratio. The projected area of ​​the particle was defined as S (m 2 ), and the circumferential length of the particle is l (m), the circularity r is expressed by the following formula: r = 4π S / l 2

[0048] [Ca / Ti ratio] Measurement was performed using a sequential X-ray fluorescence analyzer XRF-1800 (hereinafter referred to as "XRF") manufactured by Shimadzu Corporation. A calibration curve was created in advance using a standard sample containing calcium and titanium, and the amount of calcium relative to the amount of titanium (molar ratio) was determined from the peak intensity ratio and the calibration curve. When the subject was strontium titanate, the amount of strontium relative to the amount of titanium (molar ratio) was determined using the same procedure as for calcium and titanium.

[0049] [True Density] Measurement was carried out in accordance with Method A of JIS K 5101-11-1:2004. A 50 mL pycnometer, model 05520-050, manufactured by Shibata Scientific Co., Ltd., was used as the pycnometer, and SAJ special grade kerosene, manufactured by Sigma-Aldrich Japan, was used as the replacement liquid. 2.0 g of dried powder was used as the sample, and the true density was measured by adjusting the temperature to 25°C.

[0050] [Number of Combinations of Perpendicularly Intersecting Planes] The number of combinations of perpendicularly intersecting planes was evaluated using scanning electron microscope photographs of primary particles of calcium titanium double oxide particles. Specifically, calcium titanium double oxide particles were observed at a magnification of 24,000x (scanning electron microscope magnification of 20,000x x print magnification of 1.2x) using a scanning electron microscope JSM-7200F manufactured by JEOL Ltd. The angles between adjacent planes per primary particle that could be considered to be 90° were counted visually, and 100 or more particles were observed, and the average value per primary particle diameter was calculated. Note that, because this was a visual observation, angles between adjacent planes of 87.5° or more and 92.5° or less were considered to be 90°.

[0051] [Particle Size Distribution] The particle size distribution was measured using a Microtrac (registered trademark) MT3300EX II laser light diffraction and scattering particle size analyzer manufactured by Microtrac-Bell Corporation in accordance with JIS Z 8825:2022. Ion-exchanged water was used as the dispersion medium. An appropriate amount of powder was dropped into the ultrasonic dispersion tank of an automatic sample circulator attached to the measurement device, and ultrasonic dispersion was performed at an output of 40 W for 360 seconds. After this, the measurement parameters were a refractive index of 1.33 for the ion-exchanged water, reflection of the light transmittance of the particles to be measured, and a measurement time of 30 seconds. The particle diameter (X10) corresponding to 10% of the cumulative particle size distribution (volume basis) and the particle diameter (X90) corresponding to 90% of the cumulative particle size distribution (volume basis) were measured, and X90 / X10 was used as an index of particle size distribution.

[0052] [Boiled linseed oil absorption] 5.0 g of powder was heaped on a glass plate. One drop of boiled linseed oil, which had been previously stored in a microburette, was dropped onto the center of the sample, and the entire sample was uniformly kneaded with a spatula. Similarly, one or two drops of boiled linseed oil were dropped onto the sample and the kneading process was repeated until the entire sample became a hard, uniform, putty-like mass. When the amount of boiled linseed oil used is x g, the oil absorption a (g / 100 g) is expressed by the following formula: a = 100 x / 5.0

[0053] [Sodium Content] The count value of each element was measured using a simultaneous multi-element X-ray fluorescence analyzer, Simultix 15, manufactured by Rigaku Corporation, in accordance with JIS K 0119:2008, and the sodium content was calculated by the fundamental parameter method.

[0054] [Chlorine content] Using XRF, the count value of each element was measured in qualitative / quantitative standard oxide measurement mode in accordance with JIS K 0119: 2008, and the chlorine content was calculated by the Fundamental Parameter method. This method cannot detect chlorine when the chlorine content is less than 1 mg per 1.0 kg of powder, and therefore the value is below the detection limit.

[0055] [Amounts of eluted sodium, chlorine, and calcium] The powder was added to 1 L of ultrapure water at a ratio of 100 g, dispersed until uniform, and then held in an oven at 95°C for 20 hours to extract each element. The powder was then centrifuged at 3,000 rpm for 30 minutes to remove the powder (this is referred to as the "centrifugation supernatant"). The centrifuged supernatant was measured using an inductively coupled plasma optical emission spectrometer PS3520UVDD II (hereinafter referred to as "ICP") manufactured by Hitachi High-Tech Science Corporation, and the amounts of eluted sodium and calcium per 1.0 kg of powder were determined.

[0056] The amount of chlorine elution was determined by measuring a standard sample to prepare a calibration curve, and then measuring a blank and the extracted centrifuged supernatant using a DIONEX® INTEGRATION® ion chromatograph (hereinafter referred to as "ion chromatograph") manufactured by Thermo Fisher Scientific, Inc. The amount of chlorine eluted per 1.0 kg of powder was determined. When the amount of chlorine eluted per 1.0 kg of powder is less than 1 mg, it is below the quantitation limit.

[0057] [Example 1 of Raw Material Slurry Production] Metatitanic acid having a micelle diameter of 62 nm obtained by the sulfuric acid method was subjected to iron removal and bleaching treatment, and then an aqueous solution of sodium hydroxide was added to adjust the pH to 12.0, followed by desulfurization treatment. Thereafter, hydrochloric acid was added to neutralize the pH to 5.8, filtered, washed with ion-exchanged water, and the sulfur content was reduced to SO ３A metatitanic acid cake was obtained with a converted weight of 9.3 g / kg. Water was added to the washed cake to make a slurry of 2.3 mol / L in terms of Ti, and then hydrochloric acid was added to adjust the pH to 1.2, followed by peptization. The resulting slurry was designated as Raw Slurry 1.

[0058] [Raw Material Slurry Production Example 2] A metatitanic acid slurry (raw material slurry 2) was obtained in the same manner as raw material slurry 1, except that metatitanic acid with a micelle diameter of 51 nm was used, the pH during the desulfurization treatment was set to 9.0, and the pH during the deflocculation treatment was set to 1.4.

[0059] [Raw Material Slurry Production Example 3] To metatitanic acid having a micelle diameter of 62 nm obtained by the sulfuric acid method, 7.0 mol of aqueous sodium hydroxide (NaOH) was added per mol of Ti, and the mixture was heated to 95°C and stirred for 3 hours. The reaction slurry was filtered and washed with ion-exchanged water to obtain a sodium titanate cake. Water was added to the washed cake to obtain TiO ２ The resulting slurry was designated as raw material slurry 3.

[0060] [Example 1] Raw material slurry 1 was ２ 79 mol of calcium hydroxide was collected, and 91 mol of slaked lime for food additives (hereinafter referred to as "calcium hydroxide") manufactured by Marukyo Sekiryo Co., Ltd. was added to this while stirring, and then ion-exchanged water was added to make the total volume 70 L, and the temperature was raised to 35°C. 23 mol of aqueous sodium hydroxide solution (as NaOH) was added, and the temperature was raised to 98°C and the mixture was stirred for 18 hours.

[0061] The obtained slurry was filtered through a Nutsche filter and washed with ion-exchanged water until the electrical conductivity of the filtrate reached 100 μS / cm or less. After washing, the filtrate was dried in the air at 120°C. The dried solid was fired at 1050°C for 6 hours in the air. The fired product was pulverized to a mesh size of 1.0 mm using a Tokyo Atomizer Mfg. Co., Ltd. sample mill TASM-1 (hereinafter referred to as "sample mill").

[0062] The pulverized calcined product was rehydrated with water, and hydrochloric acid was added until the pH reached 5.0. The mixture was stirred for 1 hour (acid treatment). After the acid treatment, aqueous sodium hydroxide solution was added to the slurry to adjust the pH to 6.0. 1 g / kg of Dow-Toray Silicone Emulsion SM-7060EX (hereinafter referred to as "silicone oil") was added to the rehydrated calcined product and stirred for 1 hour. The mixture was then filtered through a Nutsche filter and washed with ion-exchanged water. Washing was continued until the electrical conductivity of the filtrate reached 100 μS / cm or less. After washing, the mixture was dried in air at 120°C and pulverized using a sample mill with a mesh size of 0.5 mm to obtain a powder composed of calcium-titanium double oxide particles. The powder production conditions are shown in Table 1. The various properties of the resulting powder measured using the above methods are shown in Table 2.

[0063] [Example 2] Raw material slurry 2 was used, and the amount of raw material slurry collected was ２ A powder composed of calcium-titanium double oxide particles was obtained in the same manner as in Example 1, except that the amount of calcium hydroxide added was 42 mol, the amount of calcium hydroxide added was 49 mol, the sodium hydroxide aqueous solution was added in an amount of 70 mol as NaOH, and the temperature was raised to 95°C and stirring was continued for 5 hours. The various properties of the obtained powder are shown in Table 2.

[0064] [Example 3] Raw material slurry 3 was ２ To this was added 60 mol of calcium hydroxide with stirring, and ion-exchanged water was added to make the total volume 70 L. The mixture was heated to 95°C and maintained at this temperature for 12 hours, then cooled to 50°C or below, and hydrochloric acid was added until the pH reached 5.0, followed by stirring for 2 hours (acid treatment).

[0065] After the acid treatment, the slurry was filtered through a Nutsche filter and washed with ion-exchanged water until the electrical conductivity of the filtrate reached 100 μS / cm or less. After washing, the mixture was dried in the air at 120°C and then fired in the air at 1100°C for 6 hours. The fired product was pulverized using a sample mill with a mesh size of 1.0 mm to obtain a powder consisting of calcium-titanium double oxide particles. The various properties of the obtained powder are shown in Table 2.

[0066] Example 4 A powder made of calcium-titanium double oxide particles was obtained in the same manner as in Example 1, except that the firing temperature was 1000° C. The various properties of the obtained powder are shown in Table 2.

[0067] Example 5 A powder made of calcium-titanium double oxide particles was obtained in the same manner as in Example 3, except that the firing temperature was 1200° C. The various properties of the obtained powder are shown in Table 2.

[0068] Comparative Example 1: The slurry from Example 1, after stirring at 98°C for 18 hours, was cooled to below 50°C without calcination, and hydrochloric acid was added until the pH reached 5.0, followed by stirring for 2 hours (acid treatment). The slurry after the acid treatment was filtered, washed, and dried in the same manner as in Example 1, except that the silicone oil addition and stirring were not performed. The slurry was then pulverized using a sample mill with a mesh size of 1.0 mm to obtain a powder of calcium-titanium double oxide particles. The various properties of the obtained powder are shown in Table 2.

[0069] Comparative Example 2 A powder composed of calcium-titanium double oxide particles was obtained in the same manner as in Comparative Example 1, except that the slurry from Example 2 after stirring at 95°C for 5 hours was used and the stirring time after adding hydrochloric acid was set to 1 hour. The various properties of the obtained powder are shown in Table 2.

[0070] Comparative Example 3 A powder made of calcium-titanium mixed oxide particles was obtained in the same manner as in Example 3, except that the firing step was omitted. The various properties of the obtained powder are shown in Table 2.

[0071] Comparative Example 4 Calcium-titanium mixed oxide particles were obtained in the same manner as in Example 1, except that the firing temperature was 900° C. Various properties of the obtained powder are shown in Table 2.

[0072] Comparative Example 5: Raw material slurry 2 was mixed with TiO ２68 mol of the mixture was collected, and 270 g of glucose was added. 78 mol of calcium hydroxide was added while stirring. 108 mol of aqueous sodium hydroxide (as NaOH) was then added. Ion-exchanged water was added to bring the total volume to 60 L, and the mixture was heated to 98°C. The reaction was maintained for 18 hours, then cooled to 50°C. Hydrochloric acid was added until the pH reached 5.0 and the mixture was stirred for 1 hour. The resulting mixed slurry was filtered through a Nutsche filter and washed with ion-exchanged water until the electrical conductivity of the filtrate reached 100 μS / cm or less. After washing, the mixture was dried in air at 120°C. The dried solid was pulverized using a sample mill with a mesh diameter of 1.0 mm to obtain a powder consisting of calcium-titanium double oxide particles. The various properties of the resulting powder are shown in Table 2.

[0073] Comparative Example 6: Raw material slurry 2 was mixed with TiO ２ 22 mol of strontium chloride was added to the solution of SrCl ２ 25 mol of sodium hydroxide was added with stirring, and the pH was adjusted to 4.0 by adding aqueous sodium hydroxide. Ion-exchanged water was added to bring the total volume to 70 L. After heating to 90°C, 52 mol of aqueous sodium hydroxide (as NaOH) was added over 18 hours and allowed to react. The temperature was then raised to 95°C and stirred for 1 hour. The mixture was then cooled to 50°C, hydrochloric acid was added until the pH reached 5.0, and after stirring for 1 hour, aqueous sodium hydroxide was added to adjust the pH to 6.0. Silicone oil was added at 5 g / kg relative to the solid content and stirred for 1 hour. The mixture was then decanted, filtered, and dried in air at 120°C. The dried solid was pulverized using a sample mill with a mesh diameter of 0.5 mm to obtain a powder composed of strontium-titanium double oxide particles. The various properties of the obtained powder are shown in Table 2.

[0074] Table 1 shows the production conditions for the powders of the Examples and Comparative Examples, and Table 2 shows the properties of the powders of the Examples and Comparative Examples.

[0075]

[0076]

[0077] As shown in Table 2, a powder of calcium-titanium double oxide particles having an average primary particle size of more than 500 nm and not more than 2000 nm and a circularity of 0.75 or more can be obtained by heating an aqueous solution containing a titanium source, a calcium source, and an alkali, and then calcining and acid-treating the resulting reaction product. The resulting powder has a boiled linseed oil absorption of not more than 20.0 g / 100 g, and an eluted sodium amount of not more than 120 mg, an eluted chlorine amount of not more than 20 mg, and an eluted calcium amount of not more than 420 mg per 1.0 kg of powder.

[0078] As described above, the powder made of calcium-titanium double oxide particles obtained by the present invention has a low boiled linseed oil absorption, can suppress an increase in viscosity when added to a resin, and has a small amount of electrolyte elution, making it useful as a filler to be added to a resin composition. The problems solved by the powder of the present invention are not limited to these, and it is thought to be useful in a variety of fields.

Claims

1. A powder consisting of calcium titanium double oxide particles having an average primary particle size in the range of more than 500 nm and not exceeding 2000 nm and a circularity of a projection diagram of the primary particles of 0.75 or more, wherein the powder has a boiled linseed oil absorption of 20.0 g / 100 g or less, a sodium content per 1.0 kg of powder of 3000 mg or less and a chlorine content per 1.0 kg of powder of 280 mg or less, and an amount of sodium elution measured by the method described in the Examples is 120 mg or less per 1.0 kg of powder, an amount of chlorine elution measured by the method described in the Examples is 20 mg or less per 1.0 kg of powder, and an amount of calcium elution measured by the method described in the Examples is 420 mg or less per 1.0 kg of powder.

2. BET specific surface area is 0.5m 2 / g or more 10.0m 2 The powder according to claim 1, wherein the molecular weight is 1 / g or less.

3. True density is 3600 kg / m 3 More than 4400kg / m 3 3. The powder according to claim 1 or 2, wherein:

4. The powder according to claim 1 or 2, wherein the number of combinations of perpendicular intersecting planes evaluated by the method described in the Examples using scanning electron micrographs of primary particles of the calcium titanium double oxide particles is 1.0 or less per primary particle of the calcium titanium double oxide particles.

5. The powder according to claim 1 or 2, wherein the ratio of the amount of calcium to the amount of titanium is 1.00 or more.

6. A method for producing the powder according to claim 1 or 2, comprising: wet mixing a titanium source, a calcium source, and an alkali, and heating the mixture to 85°C or higher and 100°C or lower under normal pressure to obtain a reaction product; and calcining the reaction product at 1000°C or higher and treating it with an acid.

7. A resin composition comprising the powder according to claim 1 or 2.

8. A sealing material comprising the powder according to claim 1 or 2.

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