JPWO2016017638A1 - Acicular dosonite particle powder, method for producing the same, and resin composition - Google Patents

Abstract

The object of the present invention is to provide acicular dawsonite particle powders that are easily adapted to the resin, have improved dispersibility, and have improved heat resistance. The acicular dosonite particle powder of the present invention has the following features (1) and / or (2). (1) The oil absorption amount of the acicular dosonite particle powder is 80 cc / 100 g or less, (2) the acicular dawsonite particle powder contains 0.01 to 5 wt% of one or more elements selected from alkaline earth metals and silicon And the BET specific surface area of the acicular dawsonite particle powder is 1 to 60 m 2 / g. [Selection figure] None

Description

  The present invention provides a needle-like dawsonite particle powder that is easily adapted to a resin and has improved dispersibility and improved heat resistance.

  Synthetic resins such as polypropylene are widely used for molded articles because of their excellent processability, physical properties, and chemical properties, and are used in various applications such as automotive materials. Furthermore, a composite material in which an inorganic filler is dispersed in a resin has been developed in order to impart higher physical and chemical properties while maintaining the properties of the resin. In order to maximize the properties of the inorganic filler in the composite material, the dispersibility in the resin is very important.

Dawsonite is a compound represented by the general formula: NaAl (OH) ₂ CO ₃ , which has been developed for some time and has been studied for use in antacids, flame retardants, resin reinforcements, and the like. Yes.

  Research has been conducted on the dosonite particle powder as a flame retardant and a resin reinforcing material, but the compatibility with the resin and the dispersibility when it becomes a composite material are insufficient, and further improvement is required.

  Various studies have been conducted on the dowsonite particle powder for the purpose of improving characteristics (Patent Documents 1 to 4).

Japanese Patent Laid-Open No. 55-12115 JP-A-48-96494 JP 49-34935 A JP 52-29838 A

  An example of the resin reinforcing material is Patent Document 1. The method for producing dosonite of this publication is reported in Patent Document 2. Urea is added to a sodium aluminate aqueous solution and reacted by heating to synthesize dawsonite particle powder. However, when synthesizing dawsonite by this method, ammonium ions are produced when urea is thermally decomposed, and ammonia-type dawsonite is produced, and it is possible that dawsonite particle powder with low purity may be produced. It is. The dosonite containing ammonia type dawsonite is easily decomposed at a lower temperature than the sodium type dawsonite during kneading with the resin, and the dispersibility of the dawsonite may be deteriorated by the decomposition product.

  Patent Document 3 reports a flame retardant method for a synthetic resin using dosonite as a filler. Although it is described that it is possible to disperse dosonite in a resin to make the unsaturated polyester resin flame retardant, there is no description about the properties, manufacturing method, and dispersibility of the dosonite particle powder, and how it is dispersed in the resin. It is difficult to predict whether

  Patent Document 4 describes that dawsonite that is surface-treated by dispersing dawsonite in a solvent in which an organic acidic substance having 4 or more carbon atoms is dissolved is excellent in dispersibility with respect to a synthetic resin. However, an organic acid having 4 or more carbon atoms may deteriorate the characteristics of the synthetic resin and may cause a so-called bleeding phenomenon that migrates to the resin surface, which may deteriorate the characteristics of the synthetic resin.

  In addition, it has been confirmed that dawsonite has a flame-retarding effect and is an effective substance for suppressing the combustion of the resin. However, since the decomposition temperature is low, it is pointed out that the temperature is slightly lower than the temperature at the time of combustion of the polymer (reference document; mass spectrometry Vol. 47, No. 6, 1999). Further, although the dosonite particle powder has been studied as a flame retardant and a resin reinforcing material, the dispersibility when it becomes a composite material is insufficient, and further improvement of the dispersibility is demanded. Moreover, although it may be used as a flame retardant, the performance is not enough.

  An object of the present invention is to provide a dawsonite particle powder having good compatibility and dispersibility when combined with a resin material and improved heat resistance. An object of the present invention is also to provide a resin composition containing the dosonite particle powder.

  The object can be achieved by the present invention as follows.

That is, the present invention is a needle-like dawsonite particle powder having the following characteristics (1) and / or (2) (Invention 1):
(1) Oil absorption of acicular dosonite particle powder is 80 cc / 100 g or less,
(2) The acicular dawsonite particle powder contains 0.01 to 5 wt% of one or more elements selected from alkaline earth metals and silicon, and the acicular dawsonite particle powder has a BET specific surface area of 1 to 60 m ² / g. It is.

  Further, the present invention is the needle-shaped dawsonite particle powder according to the first aspect of the present invention (Invention 2), wherein the oil absorption of the needle-shaped dawsonite particle powder is 100 cc / 100 g or less in the above feature (2).

Moreover, this invention is the acicular dawsonite particle powder of this invention 1 or 2 whose BET specific surface area is 1-25 m < ² > / g (this invention 3).

  Moreover, this invention is the acicular dawsonite particle powder in any one of this invention 1-3 whose volume average particle diameter by a laser diffraction method is 5 micrometers or less (this invention 4).

  The present invention is characterized in that it is produced by adding an aqueous aluminum salt solution to an aqueous solution containing an alkali metal carbonate, mixing and stirring, and then reacting the mixed solution at 120 to 300 ° C. in an autoclave. Or a method for producing the acicular dosonite particle powder according to any one of the above (Invention 5).

  Further, the present invention adds an aqueous solution containing at least one element selected from an alkaline earth metal and silicon in the step of adding an aluminum salt aqueous solution to an aqueous solution containing an alkali metal carbonate and mixing and stirring the solution. The production method according to the present invention 5 (invention 6).

  Moreover, this invention is a resin composition containing the dawsonite particle powder in any one of this invention 1-4 (this invention 6).

  The dawsonite particle powder according to the present invention is suitable as a filler for a resin composition because it has good compatibility and dispersibility when combined with a resin material and has improved heat resistance.

  The configuration of the present invention will be described in more detail as follows.

The acicular dawsonite particle powder of the present invention 1 has the following characteristics (1) and / or (2).
(1) Oil absorption of acicular dosonite particle powder is 80 cc / 100 g or less,
(2) The acicular dawsonite particle powder contains 0.01 to 5 wt% of one or more elements selected from alkaline earth metals and silicon, and the acicular dawsonite particle powder has a BET specific surface area of 1 to 60 m ² / g. It is.

  That is, the needle-like dawsonite particle powder of the present invention 1 may have only the feature (1) or only the feature (2), and has both the features (1) and (2). Also good. Therefore, any feature in the description of the feature (2) may be combined if the feature (1) is satisfied, and any feature in the description of the feature (1) may be combined if the feature (2) is satisfied.

  First, the case where the needle-like dawsonite particle powder of the present invention 1 has the feature (1) will be described.

  The oil absorption of the needle-like dawsonite particle powder according to the present invention 1 is 80 cc / 100 g or less. When the amount of oil absorption exceeds 80 cc / 100 g, the wettability with the resin tends to be low, so that a large amount of energy is required for kneading into the resin. A more preferable oil absorption is 75 cc / 100 g or less, and still more preferably 30 to 70 cc / 100 g.

The acicular dosonite particle powder according to the present invention is acicular and preferably has a BET specific surface area of 1 to 25 m ² / g. When the BET specific surface area of the acicular dosonite particle powder exceeds 25 m ² / g, the dispersibility when kneaded into the resin may be insufficient. If it is less than 1 m ² / g, it is difficult to produce industrially. A more preferable BET specific surface area is ² to 23 m ² / g, still more preferably 3 to 20 m ² / g.

  As for the particle size distribution of the acicular dawsonite particle powder according to the present invention, the volume average diameter by laser diffraction method is preferably 5.0 μm or less. When the volume average diameter exceeds 5.0 μm, the dispersibility when kneaded into the resin becomes insufficient. A more preferable volume average diameter is 1.0 to 4.8 μm.

  The average major axis diameter of the acicular dosonite particle powder according to the present invention is preferably 2 to 50 μm, the average minor axis diameter is preferably 0.1 to 3 μm, and the acicular ratio is (major axis diameter / minor axis diameter) 3 to 30. Is preferred. The acicular ratio is more preferably 5 to 28.

The acicular dosonite particle powder according to the present invention is a compound represented by the chemical formula NaAl (OH) ₂ CO ₃ .

  Next, the case where the acicular dosonite particle powder of the present invention 1 has the feature (2) will be described.

The acicular dosonite particle powder according to the present invention is acicular and has a BET specific surface area of 1 to 60 m ² / g. When the BET specific surface area of the acicular dosonite particle powder exceeds 60 m ² / g, the dispersibility when kneaded into the resin is insufficient. If it is less than 1 m ² / g, it is difficult to produce industrially. A more preferred BET specific surface area is 5 to 55 m ² / g, and even more preferably 7 to 50 m ² / g.

  The content of the alkaline earth metal or silicon in the acicular dawsonite particle powder according to the present invention is 0.01 to 5.0 wt%. If the content of alkaline earth metal or silicon is less than 0.01 wt%, sufficient heat resistance cannot be expected. When the content of alkaline earth metal or silicon exceeds 5.0 wt%, coarse particles of carbonate compound, sulfate compound, and hydroxide are generated. A more preferred element is barium or calcium.

  The oil absorption of the acicular dosonite particle powder according to the present invention is preferably 100 cc / 100 g or less. When the oil absorption exceeds 100 cc / 100 g, the wettability with the resin is low, so that the dispersibility when kneaded into the resin becomes insufficient. A more preferred oil absorption is 80 cc / 100 g or less, a more preferred oil absorption is 75 cc / 100 g or less, and even more preferably 30 to 70 cc / 100 g.

  The average major axis diameter of the acicular dawsonite particle powder according to the present invention is preferably 0.4 to 30 μm, the average minor axis diameter is preferably 0.02 to 2.0 μm, and the needle ratio (major axis diameter / minor axis diameter). Is preferably 3-30, more preferably 5-28.

  As for the particle size distribution of the acicular dawsonite particle powder according to the present invention, the volume average diameter by laser diffraction method is preferably 5.0 μm or less. When the volume average diameter exceeds 5.0 μm, the dispersibility when kneaded into the resin becomes insufficient. A more preferable volume average diameter is 1.0 to 4.8 μm.

The acicular dosonite particle powder according to the present invention is a compound represented by the chemical formula: NaAl (OH) ₂ CO ₃ .

  The acicular dawsonite particle powder (in features (1) and (2)) according to the present invention is excellent in heat resistance, and has a temperature of 346 ° C. or higher in the heat resistance evaluation method in Examples described later.

  The acicular dosonite particle powder according to the present invention (in the characteristics (1) and (2)) is excellent in dispersibility, and has a rank A in the dispersibility evaluation method in the examples described later.

  Next, a method for producing the acicular dosonite particle powder (in features (1) and (2)) according to the present invention will be described.

  The acicular dawsonite particle powder according to the present invention is produced by adding an aluminum salt aqueous solution to an aqueous solution containing an alkali metal carbonate, mixing and stirring, and then reacting the mixed solution at 120 to 300 ° C. in an autoclave. Is done. In the case of having the above feature (2), in the step of adding an aluminum salt aqueous solution to an aqueous solution containing an alkali metal carbonate and mixing and stirring, further, at least one selected from an alkaline earth metal and silicon An aqueous solution containing the element is added. Even in the case of having the above feature (1), an aqueous solution containing one or more elements selected from alkaline earth metals and silicon may be added.

  The alkali metal of the alkali metal carbonate in the present invention is one or a plurality of carbonates selected from water-soluble alkali metal salts such as sodium and potassium. Examples of the carbonate include sodium carbonate, potassium carbonate, and sodium bicarbonate.

  A sodium hydroxide aqueous solution may be added to the aqueous solution containing an alkali metal carbonate in the present invention. The aqueous solution of sodium hydroxide suppresses hydrolysis of the alkali metal carbonate, and at the same time brings about the effect that the particle growth is liable to occur due to dissolution and precipitation reaction.

  As the aluminum salt aqueous solution in the present invention, an aluminum sulfate aqueous solution, an aluminum chloride aqueous solution, an aluminum nitrate aqueous solution, aluminum hydroxide, or the like can be used. An aqueous aluminum sulfate solution and an aqueous aluminum chloride solution are preferred.

  As the aqueous solution containing one or more elements selected from alkaline earth metals or silicon added in the case of having the feature (2), a chloride aqueous solution, a nitric acid compound, a sulfuric acid compound aqueous solution and the like can be used. An aqueous calcium chloride solution is preferred.

  The addition amount of the alkaline earth metal or silicon aqueous solution is 0.01 to 5 wt% in terms of the weight ratio of the alkaline earth metal or silicon ion to the total amount of the produced dawsonite particle powder.

The concentration of the alkali metal carbonate aqueous solution in the present invention is preferably 0.5 to 8.0 mol / l, more preferably 0.5 to 5.0 mol / l.
The density | concentration of aluminum salt aqueous solution is 0.03-3.0 mol / l, More preferably, it is 0.05-2.5 mol / l.
The concentration of sodium hydroxide is 0 to 3.0 mol / l, more preferably 0 to 2.5 mol / l.
The ratio of the aluminum salt to the alkali metal carbonate in the reaction solution is preferably 1.5 to 8.0, more preferably 2.0 to 6.0.

  The temperature at the time of mixing and stirring in the present invention is preferably 5 to 100 ° C, more preferably 20 to 80 ° C. When a hydrogen carbonate such as sodium hydrogen carbonate is used, decomposition is accelerated at a high temperature. Therefore, the mixture is stirred at a temperature of 60 ° C. or lower. The time for mixing and stirring is preferably 1 to 10 hours, and more preferably 1 to 5 hours.

  The pH value during mixing and stirring in the present invention is preferably 7.5 to 12.5, and more preferably 8.0 to 12. When the pH value is too low, an aluminum compound other than the target product is produced. If the pH value is too high, unreacted aluminum salt remains in the reaction solution, resulting in poor reaction efficiency.

  The reaction temperature of the autoclave in the present invention is preferably 120 ° C to 300 ° C, more preferably 120 ° C to 250 ° C. If it is lower than 120 ° C., the dissolution and precipitation reaction does not proceed sufficiently and the particles are difficult to grow. Although the reaction may be carried out at a temperature exceeding 300 ° C., excessive heating is not necessary to obtain the particles of the present invention. The reaction time is 3 to 24 hours, preferably 5 to 15 hours.

  After the autoclave reaction, needle-shaped dawsonite particle powder can be obtained by washing with water and drying by a conventional method.

  The obtained acicular dosonite particle powder is pulverized by various pulverizers. As the pulverizer, a dry type pulverizer such as a hammer mill, a pin mill, a blade mill, or a jet mill is used.

  Next, the resin composition according to the present invention will be described.

The acicular dosonite particle powder according to the present invention has good dispersibility in the resin.
The resin in the present invention is an olefin polymer, and examples thereof include ethylene polymers, propylene polymers, butene polymers, styrene polymers, and homopolymers, random polymers, and block polymers thereof. It is preferable to contain 1 to 80 parts by mass of the acicular dawsonite particle powder with respect to 100 parts by mass of the resin.

  Various additives can be blended in the resin composition according to the present invention as necessary. Examples of such additives include various additives depending on the application, such as lubricants, plasticizers, flame retardants, antioxidants, antistatic agents, light stabilizers, ultraviolet absorbers, and the like. Can be added.

  Next, a method for producing the resin composition according to the present invention will be described.

  The resin composition according to the present invention can be obtained by kneading by a known method using a resin such as polypropylene, needle-like dosonite particle powder, and, if necessary, additives such as a lubricant. For example, when a film-like molded product is obtained, the film may be formed after kneading using an ordinary extruder, hot roll, plast mill, kneader or the like. A conventional inflation method, a T-die method, or the like can be used for forming the film. In order to obtain a molded product, an injection molding machine is used, and the compound created by the extruder may be molded into an arbitrary shape.

<Action>
By using the acicular dawsonite particle powder according to the present invention, the torque when the resin is kneaded can be kept low. Moreover, the dispersibility in resin improves and it can reduce an aggregate.
That is, the needle-like dosonite particle powder according to the present invention has a very good compatibility with the resin because the oil absorption is kept low, and the torque when kneaded with a resin such as polypropylene can be kept low. Furthermore, combined with a low specific surface area and a large particle size, it is possible to obtain a resin composition having high dispersibility in the resin and few aggregates.
Furthermore, the acicular dosonite particle powder according to the present invention has good dispersibility when combined with a resin material, and can improve heat resistance.
That is, the acicular dosonite particle powder according to the present invention can improve heat resistance by containing one or more elements selected from alkaline earth metals or silicon. Alkaline earth metals or silicon have been found to be useful as flame retardants at high temperatures, as represented by, for example, calcium carbonate or calcium hydroxide. In the present invention, it is considered that the heat resistance is improved by the presence of alkaline earth metal ions or compound fine particles thereof incorporated in the dawsonite structure. Furthermore, although the reason is not clear, the presence of alkaline earth metal or silicon can improve the dispersibility in the resin, and conventionally, it has been difficult to disperse in the resin with a large specific surface area. Even in the range, the dispersibility can be improved by the presence of alkaline earth metal or silicon.

  Next, examples and reference examples are given.

  Various characteristics of the acicular dosonite particle powder and the resin composition according to the present invention were evaluated by the following methods.

  The constituent phase of the acicular dosonite particle powder was identified with an X-ray diffractometer (RINT-2500, manufactured by Rigaku Corporation). Measurement was performed under the conditions of a diffraction angle 2θ of 3 to 80 °, a step angle of 0.03 °, and an FT of 0.3 sec. Cu was used as the radiation source type.

  The acicular ratio of the acicular dosonite particle powder is expressed by the ratio of the major axis diameter / minor axis diameter of the particle diameter measured using a scanning electron microscope.

  The specific surface area value was measured by the BET method using nitrogen. As a measuring apparatus, “Monosorb MS-21 (manufactured by QUANTA CHROME) was used.

  With respect to the oil absorption, according to JIS K5101-13-2, the volume of oil absorbed in 2.5 g of the dosonite particle powder was measured, and expressed in terms of per 100 g of powder.

  The volume average particle diameter of the acicular dosonite particle powder was measured by a wet measurement unit of a laser diffraction / scattering particle size distribution measuring instrument (SEISHIN COMPANY SK Laser Micron Sizer LMS-2000e). In the measurement, the sample was preliminarily dispersed for 1 minute with an ultrasonic disperser and then evaluated.

The ease of familiarity with the resin was evaluated by preparing a resin composition containing dawsonite particle powder according to the following procedure and measuring the torque.
That is, the acicular dosonite particle powder was mixed into a master batch using a biaxial kneader so that the concentration was 20%. The kneading conditions were such that the kneading temperature was 170 ° C., the rotation speed was 50 rpm, and the kneading time was 15 minutes, and the kneading was performed with a lab plast mill (manufactured by Toyo Seiki Seisakusho). The ease of familiarity with the resin was used as an index by calculating the difference between the maximum torque at the initial stage of kneading in the measured lab plast mill torque and the stable torque after 5 minutes from the start of kneading. It shows that it is easy to become familiar with resin, so that a value is small.

The dispersibility in the resin was evaluated by preparing a resin film containing the dawsonite particle powder from the master batch obtained above according to the following procedure and measuring the number of aggregates.
For film formation, a master batch of 20% acicular dosonite particle powder was press-molded by hot pressing to obtain a press film having a thickness of 100 μm. The pressurizing conditions are a press temperature of 170 ° C., a press pressure of 150 kg weight / cm ² , a press time of 1 minute, and a throughput of 0.8 g.

When the obtained film with a thickness of 100 μm is cut into 5 cm squares and observed with an optical microscope, the number of aggregates of 100 μm or more existing in a square of 1 cm square is measured. And the average value of the whole film was evaluated. A is a level that is practically acceptable.
A ... 5 or less B ... 6-10 pieces C ... 11 pieces or more

  The heat resistance of the acicular dosonite particle powder was measured by TG / DTA. The effect of improving the heat resistance by adding calcium was compared using a dosonite particle powder having an equivalent BET specific surface area. In addition, the temperature when the weight became 80 wt% from the start of weight loss was compared. In the said evaluation method, when temperature is 346 degreeC or more, it is the level which is excellent in heat resistance.

Example 1-1
2. Hold 1000 ml of 25 mol / L sodium carbonate at 60 ° C. and stir in the reaction vessel. To this, 500 ml of a 1.5 mol / L aluminum sulfate aqueous solution was added to make the total amount 1.5 L. The reaction vessel was stirred and aged at pH 8.3 and 60 ° C. for 2 hours to obtain a white slurry. The white slurry was transferred to an autoclave (ACV) and aged with stirring at 200 ° C. for 7 hours to obtain a slurry containing a white precipitate. The slurry was filtered, washed with water, and dried at 120 ° C. to obtain white particle powder.

As a result of identifying the crystal phase of this white particle powder by X-ray diffraction, it was confirmed to be dawsonite. When the obtained dosonite particle powder was observed with an electron microscope, it was confirmed to be acicular particles having a major axis / minor axis ratio of about 21. The specific surface area was 12.3 m ² / g. The oil absorption was 62 ml / 100 g, and the volume average particle size was 4.2 μm.

  Next, 20 parts by weight of the obtained acicular dosonite particle powder and 80 parts by weight of a polypropylene resin (trade name: WSX-02) were mixed, and kneaded at 170 ° C. for 15 minutes with a Laboplast mill to obtain a resin mixture. The maximum torque was 59.5 N · m, the stable torque was 7.25 N · m, and the difference between the maximum torque and the stable torque was 52.3 N · m.

  The obtained resin mixture was pressure-molded with a hot press to obtain a press film having a thickness of 100 μm. When the number of aggregates contained in the film was measured with an optical microscope, it was 0 and the dispersibility was A.

Example 1-2:
500 ml of 4.5 mol / L sodium carbonate and 500 ml of 3.0 mol / L sodium hydroxide are mixed and kept at 60 ° C. and stirred in the reaction vessel. To this, 500 ml of 0.9 mol / L aluminum sulfate aqueous solution was added to make the total amount 1.5 L. The mixture was aged at pH 9.9 and 60 ° C. for 2 hours while stirring in the reaction vessel to obtain a white slurry. The white slurry was transferred to an autoclave and aged with stirring at 200 ° C. for 7 hours to obtain a slurry containing a white precipitate. The slurry was filtered, washed with water, and dried at 120 ° C. to obtain white particle powder.

Examples 1-3, 1-4, Reference Examples 1-1 to 1-3:
Acicular dawsonite particle powder is obtained in the same manner as in Example 1-1 or 1-2, except that the type, concentration, concentration of sodium carbonate, concentration of alkaline aqueous solution, and aging temperature are variously changed. It was. Moreover, the resin composition on a film was obtained using the needle-like dosonite particle powder obtained similarly.

  Table 1 shows the synthesis conditions of Examples and Reference Examples, and Table 2 shows various characteristics of the obtained acicular dosonite particle powder.

  As shown in Table 2, the acicular dawsonite particle powder and the resin composition containing the acicular dawsonite particle powder according to the present invention have a low plastom torque and excellent compatibility with the resin, and aggregates in the resin. It was confirmed that there was little dispersibility and excellent dispersibility.

Example 2-1
2. Hold 1000 ml of 25 mol / L sodium carbonate at 60 ° C. and stir in the reaction vessel. To this, 400 ml of a 1.125 mol / L aluminum sulfate aqueous solution and 100 ml of a 0.135 mol / L sodium chloride aqueous solution were added to make the total amount 1.5 L. The mixture was aged at pH 8.7 and 60 ° C. for 2 hours while stirring in the reaction vessel to obtain a white slurry. The white slurry was transferred to an autoclave (ACV) and aged with stirring at 180 ° C. for 7 hours to obtain a slurry containing a white precipitate. The slurry was filtered, washed with water, and dried at 120 ° C. to obtain white particle powder. As a result of identifying the crystal phase of this white particle powder by X-ray diffraction, it was confirmed to be dawsonite.
When the obtained dawsonite particle powder was observed with an electron microscope, it was confirmed to be acicular particles having a major axis / minor axis ratio of about 20. The specific surface area was 23.4 m ² / g. The oil absorption was 70 ml / 100 g.

  Next, 20 parts by weight of the obtained acicular dosonite particle powder and 80 parts by weight of a polypropylene resin (trade name: WSX-02) were mixed, and kneaded at 170 ° C. for 15 minutes with a Laboplast mill to obtain a resin mixture. The obtained resin mixture was pressure-molded with a hot press to obtain a press film having a thickness of 100 μm. When the number of aggregates contained in the film was measured with an optical microscope, it was 0 and the dispersibility was A.

Example 2-2:
500 ml of 4.5 mol / L sodium carbonate and 500 ml of 0.9 mol / L sodium hydroxide are mixed, kept at 60 ° C., and stirred in a reaction vessel. To this, 400 ml of a 1.31 mol / L aluminum sulfate aqueous solution and 100 ml of a 0.165 mol / L sodium chloride aqueous solution were added to make the total amount 1.5 L. The mixture was aged at pH 9.1 and 60 ° C. for 2 hours while stirring in the reaction vessel to obtain a white slurry. The white slurry was transferred to an autoclave and aged with stirring at 160 ° C. for 7 hours to obtain a slurry containing a white precipitate. The slurry was filtered, washed with water, and dried at 120 ° C. to obtain white particle powder. As a result of identifying the crystal phase of this white particle powder by X-ray diffraction, it was confirmed to be dawsonite.
When the obtained dosonite particle powder was observed with an electron microscope, it was confirmed to be acicular particles having a major axis / minor axis ratio of about 18. The specific surface area was 55.5 m ² / g. The oil absorption was 98 ml / 100 g.

Examples 2-3 to 2-8, Reference Examples 2-1 to 2-3:
The acicular dosonite is the same as in Example 2-1 or 2-2 except that the type, concentration, concentration of alkali metal carbonate, concentration of aqueous alkali solution, and aging temperature of the aluminum compound and additive element were variously changed. Particle powder was obtained. Moreover, the resin composition on a film was obtained using the needle-like dosonite particle powder obtained similarly.

  Table 3 shows the synthesis conditions of Examples and Reference Examples, and Table 4 shows the characteristics of the obtained acicular dosonite particle powder. Table 5 shows the effect of improving heat resistance of the dosonite particle powder having the same BET specific surface area.

  As shown in Table 4, the acicular dawsonite particle powder and the resin composition containing the acicular dawsonite particle powder according to the present invention are excellent in dispersibility with few aggregates in the resin, and as shown in Table 5. It was confirmed that the powder was acicular dosonite particles with improved heat resistance.

  The dawsonite particle powder according to the present invention is suitable as a filler for a resin composition because it has good compatibility and dispersibility when combined with a resin material and has improved heat resistance.

Claims (7)

Needle-shaped dawsonite particles having the following characteristics (1) and / or (2):
(1) Oil absorption of acicular dosonite particle powder is 80 cc / 100 g or less,
(2) The acicular dawsonite particle powder contains 0.01 to 5 wt% of one or more elements selected from alkaline earth metals and silicon, and the acicular dawsonite particle powder has a BET specific surface area of 1 to 60 m ² / g. It is.   The needle-shaped dawsonite particle powder according to claim 1, wherein the oil absorption of the needle-shaped dawsonite particle powder is 100 cc / 100 g or less in the feature (2). The acicular dawsonite particle powder according to claim 1 or 2, having a BET specific surface area of 1 to 25 m ² / g.   The acicular dawsonite particle powder according to any one of claims 1 to 3, which has a volume average particle diameter of 5 µm or less by a laser diffraction method.   An aqueous aluminum salt solution is added to an aqueous solution containing an alkali metal carbonate, mixed and stirred, and then the mixture is reacted at 120 to 300 ° C in an autoclave. The method for producing the acicular dosonite particle powder according to any one of the above.   The aqueous solution containing one or more elements selected from alkaline earth metals and silicon is further added in the step of adding an aluminum salt aqueous solution to an aqueous solution containing an alkali metal carbonate and mixing and stirring. Manufacturing method.   The resin composition containing the dawsonite particle powder in any one of Claims 1-4.