JP2008144010A - Method for producing resin composition and resin composition film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a resin composition, by which a coagulation-preventing agent added in a process for forming alkaline earth metal carbonate particles are removed without coagulating the particles in a subsequent process, thereby enabling to produce the resin composition formulated with the alkaline earth metal carbonate particles and having excellent transparency. <P>SOLUTION: This method for producing the resin composition formulated with the alkaline earth metal carbonate particles is characterized by comprising a particle-forming process for forming the alkaline earth metal carbonate particles in the presence of a coagulation-preventing agent, and a removing process for removing the coagulation-preventing agent, before the formed alkaline earth metal carbonate particles are added to the resin, wherein the coagulation-preventing agent is removed in the removing process so that the coagulation-preventing agent is reduced to a content of ≤1.0 mass% based on the resin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a resin composition obtained by blending alkaline earth metal carbonate particles and a resin composition film.

  Alkaline earth metal carbonates such as calcium carbonate, strontium carbonate, and barium carbonate are used as additives for paper, rubber, resin, plastic, paint, cosmetics, pharmaceuticals, and other raw materials for dielectric ceramic materials and high-temperature superconductor materials. It is used in a wide range of industrial fields.

  Alkaline earth metal carbonates are known to have different functions and characteristics depending on their physical properties. For example, spindle-like carbonates are used for the production of paints with low gloss and excellent wet ink coverage. It is said that calcium carbonate is suitable, and acicular calcium carbonate is suitable for the production of a paint having high gloss, opacity, ink inking properties and ink setting properties. In addition, when strontium carbonate is used as a raw material for producing strontium titanate, it has been reported that electrical characteristics are improved when particles having an average particle size of 0.8 μm or less are used. Furthermore, when applied to a transparent resin or plastic material, small particles of the order of μm or less are required in order not to impair the transparency. Thus, since it is necessary to select a particle shape and a particle size according to the objective, the industrial utility value of the alkaline-earth metal carbonate particle | grains by which the form was controlled is high. Therefore, in order to precisely control the morphology of particles having anisotropic shapes such as needles and columns that are widely used in industrial applications and to fully express the intended function, more uniform particles, that is, particle sizes There is a need for a technique that can produce particles with excellent distribution.

In general, a method for producing alkaline earth metal carbonate particles includes a “liquid-gas” method in which carbon dioxide gas is reacted with a solution containing an alkaline earth metal ion called a carbon dioxide method, and an alkaline earth metal It is roughly classified into a “liquid-liquid” method in which a solution containing ions and a solution containing carbonate ions are reacted. Currently, the “liquid-gas” method is mainly carried out industrially, and as a solution containing alkaline earth metal ions, alkaline earth metal hydroxide, specifically, Ca (OH) ₂ or Sr (OH) ₂ and Ba (OH) ₂ are often used, but these hydroxides are usually used as slurries because of their low solubility.

  In the “liquid-gas” method, a method of producing columnar calcium carbonate of 1 to 2 μm by changing the temperature of the calcium hydroxide slurry and the introduction rate of carbon dioxide gas in three stages (for example, see Patent Document 1), A method of producing 1 to 2 μm spindle-shaped calcium carbonate by adding water-soluble monosaccharides or oligosaccharides to the calcium hydroxide slurry before the conversion reaction reaches 30% (for example, see Patent Document 2), strontium hydroxide slurry A method for producing a needle-shaped strontium carbonate having a thickness of 0.72 μm by defining the temperature and the introduction rate of carbon dioxide gas (for example, see Patent Document 3) has been proposed.

  However, in the “liquid-gas” method, i) it is difficult to strictly control the dissolution rate of alkaline earth metal hydroxide in the slurry and the dissolution rate of carbon dioxide gas in the slurry during the reaction process, ii) the reaction process Iii) Since nucleation is carried out in a strontium hydroxide slurry, it is difficult to uniformly stir the reaction solution, and the ion concentration and supersaturation in the reaction solution Alkaline earth metal carbonate particles that can be prepared have a wide particle size distribution due to problems such as disproportionation and nuclei formed immediately by the influence of a higher salt concentration.

  For the problem i), for example, a method of producing a calcium carbonate crystal by directly reacting an aqueous solution containing carbonate ions and an aqueous solution of a calcium compound under ultrasonic irradiation (see, for example, Patent Document 4), A method of producing acicular barium carbonate by simultaneously adding an aqueous solution of barium salt and an aqueous solution of alkali carbonate to reaction vessels from separate supply ports (see, for example, Patent Document 5), and similarly strontium, calcium, barium, zinc A method of producing needle-like and rod-like carbonates by reacting a metal ion source containing at least one selected from each ion of lead and a carbonate source in a liquid by a double jet method (see, for example, Patent Document 6) A method using a “liquid-liquid” method is proposed. However, since these methods do not have technical means that can solve the problem shown in the section ii), the particle size distribution of the particles that can be produced is still unsatisfactory.

  For the problem described in the above item ii), a production method of reacting a carbonic acid source in a liquid of a metal ion source containing at least one selected from ions of strontium, calcium, barium, zinc, and lead, There has been proposed a method for producing a carbonate having a shape with an aspect ratio larger than 1, which includes a step of increasing the number of particles and a step of increasing the volume of the particle and reacting by controlling the addition rate and time of the carbonic acid source (for example, Patent Documents). 7). However, this method is a manufacturing method including the problem described in the item i) because the method of adding the ion source is the single jet method, and carbonation into the metal ion source stored in the reaction vessel. Since the source is added, the problem described in the item iii) is unavoidable, and is insufficient as a technique for improving the deterioration of the particle size distribution.

  In addition, alkaline earth metal carbonates produced by the “liquid-gas” method originally have a very strong cohesion between primary particles (core particles), and a large number of primary particles aggregate to form a large secondary. Particles (coarse aggregates of primary particles) are formed, and the slurry of secondary particles is said to be impossible to disperse to primary particles even if stirring is continued for a long time. . For example, when calcium carbonate containing a large number of aggregates of such primary particles is used as a filler or pigment for rubber, plastic, paper, paint, etc., the secondary particles behave like primary particles. Insufficient dispersion, a decrease in strength, a decrease in gloss, a decrease in fluidity, and the like are caused, and the original effect that is manifested when primary particles are blended cannot be obtained. Similarly, even when calcium carbonate containing a large number of aggregates is subjected to an inorganic or organic surface treatment, only the surface of the secondary particles is treated, and a sufficient effect can be obtained. difficult.

  Many methods for dispersing primary particle aggregates in such alkaline earth metal carbonate particles have been reported, and industrially, a method of strongly pulverizing by a ball mill, a sand grinder mill or the like is employed. However, since this method is grinding and grinding using enormous energy, the aggregates are dispersed and the primary particles are destroyed at the same time. As a result, the surface state of the particles becomes unstable and added. Therefore, it is difficult to say that this is a preferable method because particles smaller than the desired primary particle size and secondary agglomerated particles incompletely dispersed are mixed and the particle size distribution becomes wide. In addition, in such a wet grinder such as a sand grinder, fine glass beads may be used as a grinding medium. However, in the grinding process of alkaline earth metal carbonate particles, the surface of these glass beads is also destroyed. Therefore, a large number of coarse glass pieces of several μm or more may be mixed in the alkaline earth metal carbonate particles after the dispersion treatment, and it is difficult to say that this is a preferable method.

  Further, since the carbonic acid source is added to the metal ion source stored in the reaction vessel, the problem described in the item iii) is unavoidable, and it is insufficient as a technique for improving the deterioration of the particle size distribution.

  In order to solve this problem, a technique has been reported in which a protective colloid is formed by reacting a metal ion source and a carbonate ion source in the presence of an anti-aggregation agent to improve and improve the deterioration of the particle size distribution due to aggregation (for example, (See Patent Document 8).

  However, in the methods introduced in the above documents, it becomes extremely difficult to form a strong agglomerated structure in the drying process following the particle synthesis and to form primary particles while maintaining the particle shape in the subsequent dispersion process. In addition, when such alkaline earth metal carbonate particles are used in a transparent resin or plastic material, the water-soluble aggregation inhibitor added during the particle synthesis causes phase separation in the final product, resulting in transparency. There was a problem that significantly deteriorated.

Therefore, there is a need for a method that does not require a pulverization process and that can stably produce alkaline earth metal carbonate particles having few aggregated particles.
Japanese Patent Publication No.55-51852 JP 2001-139328 A JP 2006-124199 A JP 59-203728 A JP-A-5-155615 JP 2006-21988 A JP 2006-169038 A JP 2006-176367 A

  The object of the present invention is to remove the agglomeration inhibitor added at the step of forming the alkaline earth metal carbonate particles without causing the particles to agglomerate in the subsequent step, and to further improve the transparency obtained by blending the particles. Another object of the present invention is to provide a method for producing a resin composition.

  The above object of the present invention can be achieved by the following configuration.

  1. In a method for producing a resin composition comprising alkaline earth metal carbonate particles blended, a particle forming step in which the alkaline earth metal carbonate particles are formed in the presence of an agglomeration inhibitor, and the formed alkaline earth metal A removal step of removing the aggregation inhibitor before mixing the carbonate particles in the resin, and removing the aggregation inhibitor to 1.0% by mass or less based on the resin in the removal step. A method for producing a resin composition, comprising:

  2. 2. The method for producing a resin composition as described in 1 above, wherein the alkaline earth metal carbonate particles are formed by a double jet method in which alkaline earth metal ions and carbonate ions are reacted.

  3. 3. The resin according to 1 or 2 above, wherein the alkaline earth metal carbonate particles are formed in the presence of an aggregation inhibitor in an amount of 1.0% by mass or more and less than 6.0% by mass with respect to the reaction solution. A method for producing the composition.

  4). Any one of said 1-3 which has a desalting process and a solvent substitution process after the said particle | grain formation process, and at least any one chosen from a desalting process and a solvent substitution process serves as the said removal process. The manufacturing method of the resin composition of description.

  5. At least one selected from the desalting step and the solvent replacement step is a membrane separation method using an ultrafiltration membrane, and the ultrafiltration membrane has a fractional molecular weight capable of passing through the aggregation inhibitor. 5. The method for producing a resin composition as described in 4 above.

  6). 6. The method for producing a resin composition according to any one of 1 to 5, wherein the aggregation inhibitor is a water-soluble polymer containing a nitrogen atom.

  7. A resin composition film comprising the resin composition obtained by the method for producing a resin composition according to any one of 1 to 6 above.

  According to the present invention, the anti-agglomeration agent added during the step of forming the alkaline earth metal carbonate particles is removed without the particles aggregating in the subsequent step, and the resin having excellent transparency formed by blending the particles. A method for producing the composition could be provided.

  The present invention will be described in more detail. In the present invention, 1.0% by mass or less of the aggregation inhibitor with respect to the resin means that it is 1.0% by mass or less with respect to the mass of the resin used for substantially molding the resin composition. In other words, when a plurality of types of resins are used in combination, the amount is expressed with respect to the combined mass. By removing the aggregation inhibitor in this manner, phase separation between resins having poor compatibility can be suppressed, and high transparency of the resin composition can be obtained. A more preferred anti-aggregation agent amount is preferably 0.8% by mass or less, and most preferably 0.5% by mass or less based on the resin.

《Alkaline earth metal carbonate》
The alkaline earth metal carbonate according to the present invention can be formed by reacting an alkaline earth metal ion and a carbonate ion. Examples of the alkaline earth metal ion source include Ca ²⁺ , Sr ²⁺ , Ba ²⁺ and Ra ²⁺ , and specific compounds in the case of Ca ²⁺ include CaCl ₂ and Ca (NO ₃ ). ₂ , CaSO ₄ , Ca (OH) ₂ , Ca (CH ₃ COO) ₂ , and hydrates thereof. The same applies to specific compounds in the case of Sr ²⁺ , Ba ²⁺ , and Ra ²⁺ . Examples of the compound that can be used as the carbonate ion source include Na ₂ CO ₃ , NaHCO ₃ , K ₂ CO ₃ , KHCO ₃ , (NH ₄ ) ₂ NO ₃ , NH ₄ HCO ₃ , (NH ₂ ) ₂ CO, and the like. Is mentioned. In the present invention, both an alkaline earth metal ion source and a carbonate ion source are more preferably compounds that have a high solubility in a solvent and can prepare a high-concentration solution.

<Particle formation process>
In the present invention, the alkaline earth metal carbonate particle forming step preferably includes a nucleation step and a particle growth step. The nucleation step is a process for generating nuclear particles, and the particle growth step means a process for growing particles with little generation of new nuclear particles. In other words, the number of particles increases in the nucleation step and does not substantially increase in the particle growth step (the number of particles may decrease when Ostwald ripening is performed). Therefore, both processes can be distinguished by the presence or absence of new nuclei. Here, the number of particles does not substantially increase means that the number of particles at the end of the particle growth step is within 125% at the start of the particle growth step (when the ripening step is included, the end of the ripening step). means.

  As described above, as a method for producing an alkaline earth metal carbonate, a method in which carbon dioxide gas is introduced into a solution of an alkaline earth metal salt to cause a reaction (“liquid-gas” method), an alkaline earth metal, or A method of reacting a salt solution with a solution containing carbonate ions (“liquid-liquid” method) is known. In any method, when alkaline earth metal ions and carbonate ions react, precipitation of alkaline earth metal carbonate occurs immediately. Since the alkaline earth metal carbonate fine particles generated by the reaction start growing immediately after the generation of the core particles, the core particles generated earlier are more likely to grow, and the core particles generated later are less likely to grow. As a result, particle growth during the nucleation step is not preferable because it increases the particle size distribution of the core particles and causes deterioration of the particle size distribution after the completion of particle growth. The broadening of the particle size distribution of the nuclei that occurs during the nucleation process depends greatly on the nucleation time and the nucleation temperature. That is, if the time of the nucleation process is long, the particle size distribution is deteriorated due to the growth of the nucleus particles generated earlier, and if the temperature of the nucleation process is high, the growth rate of the nucleus particles is increased. The difference in particle size from the nuclear particles generated later is amplified.

  In the present invention, the time for the nucleation step can be arbitrarily set, but it is preferably completed within 1800 seconds, more preferably within 300 seconds, and even more preferably within 120 seconds in order to prevent deterioration of the particle size distribution. Similarly, the temperature of the nucleation step can be arbitrarily set. However, in order to suppress the growth of nuclei particles during the nucleation step, the temperature is preferably as low as possible, specifically -10 ° C to 40 ° C. It is preferable to carry out between. At a lower temperature, the liquid in the reaction vessel freezes, special equipment is required for temperature control, and production costs increase.

  As a nucleation method, a so-called carbon dioxide method in which only carbon dioxide gas is introduced into an alkaline earth metal salt solution and a double jet method in which an alkaline earth metal salt solution and a solution containing carbonate ions are simultaneously added can be selected. However, it is preferable to apply a double jet method in which nucleation is easily controlled. In the double jet method, it is possible to increase the number of nuclei generated per unit time by increasing the degree of supersaturation in the stirring and mixing apparatus, thereby shortening the time of the nucleation process and improving the distribution deterioration in the nucleation process. It becomes possible.

  The double jet method as referred to in the present invention means that two types of solutions are dropped, injected, or injected onto the liquid surface of the liquid in the reaction vessel or into the liquid, respectively, using an appropriate liquid feeder as required. Thus, in the present invention, an alkaline earth metal salt solution and a carbonate solution can be used as the additive solution.

  In the double jet method, it is possible to arbitrarily set or change the molar addition rate by changing the addition rate of the additive solution with a liquid delivery device or the like. Since the number of core particles formed per unit decreases, the production efficiency decreases, and when the number of core particles formed by increasing the addition time is increased, the generated cores grow in parallel and the particle size distribution deteriorates. . Therefore, in this invention, it is preferable to set the molar addition rate in the said nucleation process to 0.1 mol / min or more per 1 mol of alkaline earth metal carbonate formed in this process. Furthermore, 0.2-4 mol / min is preferable and 0.5-2 mol / min is more preferable. When the molar addition rate is higher than 4 mol / min, the stirring efficiency in the reaction vessel is relatively lowered, and non-uniform nuclei are generated, and there is an increased concern about the occurrence of aggregation due to an increase in local nuclear density. .

  In the grain growth step of the present invention, it is important to react alkaline earth metal ions and carbonate ions so that new crystal nuclei are not generated. For this purpose, it is necessary to adjust the addition rate of the alkaline earth metal salt solution and the solution containing carbonate ions when the particle growth step is performed by the double jet method, and when the particle growth step is performed by the carbon dioxide method, It is necessary to adjust the gas introduction speed. In the present invention, after completion of the nucleation step, the liquid temperature in the reaction vessel can be maintained higher than the nucleation step (aging step) as necessary. In the normal ripening step, a phenomenon (ostwald ripening) occurs in which particles having a small particle size are dissolved and particles having a large particle size are grown. Therefore, in the present invention, the ripening step can be regarded as a part of the particle growth step. The particle growth step is preferably performed at a temperature equal to or higher than that of the nucleation step in order to increase the particle growth rate, and specifically, it is preferably performed between 0 ° C. and 60 ° C. Since a sufficient particle growth rate cannot be obtained at a temperature lower than 0 ° C., a long time is required for the particle growth step, and at 60 ° C. or higher, the diameter of the acicular particles or columnar particles becomes large and it is difficult to increase the aspect ratio.

  In the present invention, the aspect ratio is the ratio (major axis diameter / minor axis diameter) of the length (major axis diameter) and the diameter (minor axis diameter) of particles having a needle-like or columnar morphology, and the average aspect ratio. Means an arithmetic average value obtained by obtaining individual aspect ratios of 300 or more particles. When calculating the average aspect ratio, the average value of the major axis diameter and the minor axis diameter can also be obtained. The present invention is particularly useful for producing an alkaline earth metal carbonate having an acicular or columnar form having an average aspect ratio of 2 or more.

  In order to obtain acicular particles or columnar particles having a high aspect ratio, there are a method of forming nuclei particles having a high aspect ratio in the nucleation step and a method of increasing the aspect ratio in the particle growth step. An attempt to increase the ratio often involves deterioration of the particle size distribution. In the present invention, the particle size distribution is more important than the aspect ratio as the characteristics of the nuclei obtained in the nucleation step. This is because the formation of more uniform nuclei in the nucleation stage greatly contributes to the improvement of the particle size distribution after the grain growth. Therefore, in the present invention, it is preferable to use low aspect ratio particles in which the particle size distribution does not easily deteriorate at the nucleation stage, and the major axis diameter is selectively grown while suppressing the minor axis diameter growth in the grain growth process. It is preferable to form high aspect ratio particles.

Therefore, the alkaline earth metal carbonate particles according to the present invention have an average aspect ratio of nuclei particles at the end of the nucleation step of AR ₁ (= a ₁ / b ₁ ) and an average aspect ratio of the particles at the end of the particle growth step. Is AR ₂ (= a ₂ / b ₂ ), AR ₁ is preferably 1 or more and 2 or less, more preferably 1 or more and 1.5 or less. At the same time, AR ₂ / AR ₁ is preferably 2 or more, more preferably 3 or more, and still more preferably 5 or more. Here, a ₁ and b ₁ are the major axis diameter average value and minor axis diameter average value at the end of the nucleation step, respectively, and a ₂ and b ₂ are the major axis diameters of the particle at the end of the grain growth step, respectively. The average value and the minor axis diameter average value.

  In the present invention, the particle size is expressed by the diameter of a circle having an area equal to the projected area of the alkaline earth metal carbonate particles, and the average particle size is an arithmetic operation obtained by obtaining individual particle sizes for 300 or more particles. Mean average value. The particle size distribution is represented by a value obtained by multiplying the value obtained by dividing the standard deviation of each particle size used for obtaining the average particle size by the average particle size by 100.

Particle size distribution (%) = standard deviation of particle size / average particle size particle × 100
The present invention is useful for producing alkaline earth metal carbonate particles having an excellent particle size distribution. The alkaline earth metal carbonate particles according to the present invention preferably have a particle size distribution of 25% or less, and more preferably 20% or less. The average particle size is preferably 250 nm or less, and more preferably 150 nm or less. When the major axis diameter and the minor axis diameter distribution are defined by the same method as the particle size distribution, the major axis diameter distribution is preferably 40% or less, more preferably 30% or less, and the minor axis diameter distribution is It is preferably 30% or less, and more preferably 20% or less. Moreover, it is preferable that the average value of a major axis diameter is 80-500 nm, 100-350 nm is more preferable, 100-250 nm or less is still more preferable. The average minor axis diameter is preferably 10 to 80 nm, more preferably 15 to 70 nm, and still more preferably 20 to 60 nm.

  The long axis, short axis, and projected area of each particle required to calculate the above average aspect ratio, average particle size, and growth rate ratio can be measured from an electron microscope image. It can also be obtained using.

  In the present invention, the molar ratio of the raw materials (alkaline earth metal salt and carbonate) consumed in the nucleation step and the particle growth step can be arbitrarily changed, but the needle-like particles having an average aspect ratio of 2 or more In order to form columnar particles, it is advantageous to reduce the molar ratio of the alkaline earth metal carbonate formed in the nucleation step to the alkaline earth metal carbonate at the end of particle formation. This is because the particle growth process greatly contributes to the formation of the anisotropic shape of needle-like particles or columnar particles. Therefore, in the present invention, the molar ratio of the alkaline earth metal carbonate formed in the nucleation step is preferably set to 50 mol% or less, more preferably 30 mol% or less, and more preferably 20 mol% or less. .

<Aggregation inhibitor>
The aggregation inhibitor according to the present invention can be used regardless of a natural product or a synthetic compound as long as it has a function of adsorbing to the particle surface and expressing the aggregation suppression or aggregation prevention effect due to steric repulsion. Furthermore, a water-soluble polymer is desirable.

  Examples of the water-soluble polymer that can be used in the present application include gelatin, starch, guar gum, alginate, methyl cellulose, ethyl cellulose, hydroxyalkyl cellulose, carboxyalkyl cellulose, polyacrylamide, polyethyleneimine, polyethylene glycol, polyalkylene oxide, Polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl methyl ether, carboxyvinyl polymer, polyacrylic acid, sodium polyacrylate, naphthalene sulfonic acid condensate and the like can be mentioned, among which polyvinyl alcohol, polyvinyl pyrrolidone, polyethyleneimine, hydroxyethyl cellulose and the like are preferable. Can be used.

  Further, in the present application, it is preferable to have an adsorption ability to the particle surface, and a water-soluble polymer containing a nitrogen atom is desirable. Examples of water-soluble polymers containing nitrogen atoms include amine structures, amide structures, imine structures, and nitrile structures. The most preferred water-soluble polymers containing nitrogen atoms that can be used in the present application are polyvinylpyrrolidone and polyethylene. I can mention imine.

  In order to fully demonstrate the effects of the present application, the alkaline earth metal carbonate particles need to be formed in the presence of an agglomeration inhibitor. A preferable amount of the aggregation preventing agent is preferably formed in the presence of an aggregation preventing agent of 1.0% by mass or more and less than 6.0% by mass with respect to the reaction solution. More preferably, it is 2.0 mass% or more and 5.0 mass% or less, Most preferably, it is 3.0 mass% or more and 4.0 mass% or less. If the amount is less than 1.0% by mass, it is difficult to obtain an effect as an aggregation inhibitor. On the other hand, the amount is preferably less than 6.0% by mass from the viewpoint of lowering the stirring efficiency due to an increase in the viscosity of the reaction solution.

  Here, the reaction solution indicates a solution in a stirring field, and more specifically indicates the total amount of the solution in the reaction field in which an alkaline earth metal ion source and a carbonate ion source are mixed. Preferably, when the alkaline earth metal ion source and the carbonate ion source solution are added to the reaction solution to form particles, it is more preferable to add the agglomeration inhibitor as the reaction solution increases in volume.

<< Desalting step and solvent replacement step >>
It is preferable to have a desalting step and a solvent substitution step after the particle formation step, and the desalting step and / or the solvent substitution step also serve as the removal step. Further, it is more preferable to remove the aggregation inhibitor in the solvent replacement step.

  In the desalting step and / or the removal step of the aggregation inhibitor in the solvent replacement step, it is preferable to add a polymer dispersant or the like to be described later.

  The desalting step and the solvent replacement step are preferably processes that do not undergo drying of the particles. In general, fine particles tend to form a strong agglomerate aggregate structure when dried, and a large amount of energy is required to disperse the aggregate. Also, the primary particles are broken at the same time as the aggregates are crushed. It becomes extremely difficult to make primary particles while maintaining the shape.

  The desalting step and / or solvent replacement step is preferably a membrane separation method using an ultrafiltration membrane. Further, the molecular weight of the ultrafiltration membrane is preferably such that the ultrafiltration membrane can pass through the anti-aggregation agent, and the molecular weight cut-off of the ultrafiltration membrane is preferably 100,000 or more with respect to the molecular weight of the anti-aggregation agent used. High, more preferably 200,000 or more. As the material for the ultrafiltration membrane, cellulose-based, polyethersulfone-based, PTFE, or the like can be selected, and polyethersulfone-based or PTFE is preferably used.

  Any method may be used for desalting the preparation of the alkaline earth metal carbonate fine particles in the present invention. For example, the particles may be precipitated by centrifugation in a liquid, the supernatant removed, and the dispersion medium added again, or the salt may be removed out of the system using an exchange membrane such as an ultrafiltration membrane. In order to prevent particle aggregation, a method using an ultrafiltration membrane is desirable. Moreover, it may be changed to a dispersion medium having properties suitable for the final product simultaneously with desalting.

<Dispersant>
As a method for suppressing the agglomeration of fine particles in a solvent and highly dispersing, a polymer-based dispersant or an activator having a polar part and a non-polar part is adsorbed on the particle surface, and the steric hindrance effect causes the aggregation of the aggregate. There is a method to suppress the generation. The structure of the dispersant is not particularly limited, and is not particularly limited, such as phosphoric acid, sulfonic acid, carboxylic acid, nonionic, and cationic. These are described in, for example, JP-A-61-243837.

  In the practice of the present invention, it is preferable to use a dispersant that exhibits adsorptivity by acid-base interaction with the acid-base site on the carbonate surface, and it is more preferable to use a dispersant having an adsorbing group in at least one site of the dispersant. . For example, a dispersant having an adsorbing group such as a phosphoric acid group, a sulfonic acid group, a carboxylic acid group, or a salt or ester thereof can be preferably used. In the present invention, when fine particles are blended in the resin composition, It is most preferable to use a dispersant having a phosphoric acid group which is a stronger adsorbing group because the adhesion with the resin may be impaired by stretching the resin composition.

  The molecular weight of the dispersant used in the present invention is preferably 100,000 or less, more preferably 500 to 50,000, and most preferably 1,000 to 20,000. This is particularly noticeable when using nanoparticles with a small particle size and a dispersant with multiple adsorbing groups in one molecule. If the molecular weight is too large, the dispersant forms bridging aggregates between the particles. This is not preferable. If the molecular weight is too small, the molecular chain is short and sufficient steric hindrance effect cannot be obtained.

  Another property required for the dispersant is affinity with the resin. In order to obtain a sufficient steric hindrance effect, it is important how the polymer chain of the dispersant extends in the solvent containing the resin. This affinity can be easily evaluated by the white turbidity when the resin and the dispersant are dissolved in a solvent and the transparency of the cast film. Moreover, each solvent-resin-dispersant can be preferably designed by comparing the Hansen solubility parameter as a compatibility parameter.

  A preferable addition amount of the dispersant used in the present invention is preferably 1.0 to 50.0 mass%, more preferably 1.0 to 30.0 mass%, most preferably based on the mass of fine particles to be blended. It is 2.0-10.0 mass%. If the addition amount is small, a sufficient dispersion effect cannot be obtained, and if it is too large, bridging aggregation and precipitation are caused, which is not preferable.

  As for the surface treatment operation, there are a dry method in which particles are dried and a wet method in which a surface treatment agent is added, stirred and mixed in the state of a dispersion in the liquid. In the present invention, any method may be used, but a wet method is preferable in view of uniformity of surface treatment. It is preferable to perform ultrasonic irradiation with an ultrasonic disperser or dispersion with a media disperser during the surface treatment operation because the uniformity of the surface treatment is increased.

  Nonionic dispersants are interfacial dispersants having nonionic hydrophilic groups such as polyoxyethylene, polyoxypropylene, polyoxybutylene, polyglycidyl and sorbitan, and specifically include polyoxyethylene alkyl ether, polyoxyethylene Ethylene alkyl phenyl ether, polyoxyethylene-polyoxypropylene glycol, polyhydric alcohol fatty acid partial ester, polyoxyethylene polyhydric alcohol fatty acid partial ester, polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, fatty acid diethanolamide, triethanolamine fatty acid Mention may be made of partial esters.

  Examples of anionic dispersants are carboxylate, sulfate, sulfonate, and phosphate ester salts. Typical examples include fatty acid salts, alkylbenzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfonates, α -Olefin sulfonate, dialkylsulfosuccinate, α-sulfonated fatty acid salt, N-methyl-N oleyl taurine, petroleum sulfonate, alkyl sulfate, sulfated oil, polyoxyethylene alkyl ether sulfate, poly Examples thereof include oxyethylene alkyl phenyl ether sulfate, polyoxyethylene styrenated phenyl ether sulfate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, and naphthalene sulfonate formaldehyde condensate.

  Examples of cationic dispersants include amine salts, quaternary ammonium salts, pyridium salts, etc., and primary to tertiary fatty amine salts, quaternary ammonium salts (tetraalkyl ammonium salts, trialkylbenzyl ammonium salts, alkyls). Pyridium salt, alkylimidazolium salt, etc.). Examples of the amphoteric dispersant include carboxybetaine and sulfobetaine, and examples thereof include N-trialkyl-N-carboxymethylammonium betaine and N-trialkyl-N-sulfoalkyleneammonium betaine.

The fluorine-based dispersant is a dispersant having a fluorocarbon chain as a hydrophobic group. Examples of the fluorine-containing _{dispersant, C 8 F 17 CH 2 CH} 2 O- (CH 2 CH 2 O) 10 -OSO 3 Na, C 8 F 17 SO 2 N (C 3 H 7) (CH 2 CH 2 O) _{16 -H, C 8 F 17 SO} 2 N (C 3 H 7) CH 2 COOK, C 7 F 15 COONH 4, C 8 F 17 SO 2 N (C 3 H 7) - (CH 2 CH 2 O) 4 _{- (CH 2) 4 -SO 3} Na, C 8 F 17 SO 2 N (C 3 H 7) (CH 2) 3 -N + (CH 3) 3 · I -, C 8 F 17 SO 2 N (C _{3 H 7) CH 2 CH 2} CH 2 N + (CH 3) 2 -CH 2 COO -, C 8 F 17 CH 2 CH 2 O (CH 2 CH 2 O) 16 -H, C 8 F 17 CH 2 CH ₂ O (CH ₂ ) ₃ —N ⁺ (CH ₃ ) ₃ .I ⁻ , H (CF ₂ ) ₈ —CH ₂ CH ₂ OCOCH ₂ CH (SO ₃ ) COOCH ₂ CH ₂ CH ₂ CH ₂ (CF ₂ ) _{8 -H, H (CF 2) 6} CH 2 C H ₂ O (CH ₂ CH ₂ O) ₁₆ —H, H (CF ₂ ) ₈ CH ₂ CH ₂ O (CH ₂ ) ₃ —N ⁺ (CH ₃ ) ₃ .I ⁻ , H (CF ₂ ) ₈ CH _{2 CH 2 OCOCH 2 CH (SO 3} ) COOCH 2 H 2 CH 2 CH 2 C 8 F 17, C 9 F 17 -C 6 H 4 -SO 2 N (C 3 H 7) (CH 2 CH 2 O) 16 - H, C ₉ F ₁₇ —C ₆ H ₄ —CSO ₂ N (C ₃ H ₇ ) (CH ₂ ) ₃ —N ⁺ (CH ₃ ) ₃ · I ^−, etc. Absent.

<Surface modifier>
In the present invention, the surface of the fine particles is preferably modified with a surface modifier having a carboxylic acid group. The surface modifier that can be used in the present invention is not particularly limited as long as it has a carboxylic acid group, and can be appropriately selected according to the affinity with the resin. In addition, as the surface modifier for carbonate fine particles, a modifier having a phosphoric acid group, a modifier having a sulfonic acid group, a titanate coupling agent, an aluminate coupling agent, etc. can be used. In the practice of the invention, carboxylic acids having a relatively high pKa and a low pH are used. In addition, since the carbonate surface exhibits strong hydrophilicity, it is preferably hydrophobized to some extent when blended into the resin. As a structure having a carboxylic acid group, a surface modifier having a carbon chain (alkyl group) is used. preferable.

  Specific examples of the surface modifier used in the present invention are selected from the group consisting of saturated fatty acids, unsaturated fatty acids, aliphatic carboxylic acids, and resin acids, and more specifically, propionic acid, butyric acid, valeric acid. , Caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, 2-ethylbutyric acid, 2-ethylhexanoic acid , Isononanoic acid, isodecanoic acid, neodecanoic acid, isotridecanoic acid, isopalmitic acid, isostearic acid, myristoleic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, beef tallow stearic acid, palm kernel fatty acid, palm fatty acid, palm fatty acid, Palm stearic acid, beef tallow fatty acid, soybean fatty acid, partially cured par Saturated fatty acids such as nuclear fatty acid, partially cured coconut fatty acid, partially cured beef tallow fatty acid, partially cured soy fatty acid, extremely cured palm kernel fatty acid, extremely cured coconut fatty acid, extremely cured beef tallow fatty acid, extremely cured soy fatty acid, unsaturated fatty acid and saturated unsaturated Mixed fatty acid ammonium salt or amine salt, potassium salt, sodium salt, etc., ammonium salt or amine salt of alicyclic carboxylic acid such as naphthenic acid, potassium salt, sodium salt, etc., abietic acid, pimaric acid, parastolic acid, neoabieticin Examples thereof include ammonium salts or amine salts, potassium salts and sodium salts of resin acids such as acids.

  The preferred carbon chain length of the surface modifier that can be used in the present invention is about C6 to C22, more preferably C8 to C18, and most preferably about C10 to C14.

  In the present invention, at least two kinds of the surface modifiers are added, and the carbon chain length of each surface modifier is preferably different in order to obtain the effects of the present invention. In this case, it is preferable that at least the surface treatment agent having the shortest carbon chain length is added in an amount of 60 to 95 mol% based on the total molar amount of the surface treatment agent to be used. More preferably, it is 70 to 90%, and most preferably 75 to 85%.

  The number of carbon atoms of the surface modifier having the shortest carbon chain length is preferably 8 to 14, more preferably 9 to 12, and most preferably 9 to 11. Moreover, 15-20 are preferable, as for carbon number of other surface modifiers, 16-20 are more preferable, and 17-19 are the most preferable.

  For example, it is preferable to add stearic acid having 18 carbon atoms and decanoic acid having 10 carbon atoms at the same time to perform the modification treatment because the dispersibility is improved in combination with a dispersant described later. This is presumably because when a modifier having an alkyl group of the same length is applied to the particle surface at a high density, it becomes a rigid state and the molecular mobility of the alkyl group is limited.

  In combination with the dispersant, it is necessary to appropriately perform the hydrophobizing treatment with the surface modifier for the same reason. The surface modifier used in the present application preferably has an adsorption rate of 10 to 50 mol%, more preferably 15 to 35 mol%, and most preferably 20 to 30 mol% with respect to the surface base amount of the carbonate fine particles. It is. If the adsorption rate is low, the particle surface is not sufficiently modified and it is difficult to obtain an effect. On the other hand, if the adsorption rate is too high, sufficient particle dispersibility cannot be obtained for the reasons described above, which is not preferable.

  The surface base amount referred to here is obtained by adsorbing an acid with a known concentration to the untreated particles and titrating the residual acid amount in the solution with a suitable alkaline solution, so that the number of base adsorption sites on the surface is calculated in reverse. Can be sought.

  The addition amount of the surface modifier is preferably 0.1% by mass to 10.0% by mass, more preferably about 0.5% by mass to 5% by mass with respect to the amount of particles at the time of dispersion. Is well balanced.

  In addition, in the reaction process of the particle surface treatment agent, a certain amount of adsorption can be obtained by stirring at room temperature, but in order to further improve the amount of adsorption, particle aggregation is solved in various commonly used dispersers. However, it is preferable to carry out. Specifically, a disperser such as a bead mill disperser or an ultrasonic homogenizer can be used. In the present invention, it is preferable to use an ultrasonic homogenizer.

<Surface treatment method>
In the present invention, it is preferable to use the surface modifier and a dispersant in combination. In the surface treatment step, the surface modifier and the dispersant may be added at the same time, but it is preferable that the dispersion treatment is performed after the surface modifier is treated and the dispersion treatment is performed because of excellent dispersibility. More preferably, after the surface modifier is sufficiently adsorbed on the surface of the carbonate fine particles, it is preferable to perform a dispersion treatment by adding a dispersant. This is because the carbonate fine particle surface has high hydrophilicity, so that the adsorption reaction proceeds more gently after the surface of the fine particle is hydrophobized and then treated with a dispersant having an adsorbing group, so that aggregation is suppressed. It is guessed.

  Moreover, it is preferable to perform the reaction process of a dispersing agent, after adding the said dispersing agent, dissolving particle aggregation in the various well-known dispersers. Specifically, any of a media disperser, an ultrasonic disperser, a high-speed stirring disperser, or a combination thereof can be used. A media type dispersing machine is one in which beads or the like are introduced into the apparatus, and the particles are dispersed by collision or shearing between the bead particles. As a specific example of the apparatus that can be used in the present invention, Kotobuki Apex Mill, Ashizawa Kogyo LMZ and the like. For the purpose of breaking up the agglomeration without crushing the primary particles, it is preferable to use beads having a small particle size. It is preferable to use beads having an average particle diameter of 0.3 mm or less, more preferably beads having an average particle diameter of 0.1 mm or less. As the bead type, glass, titania, alumina, zirconia, or the like can be used. The ultrasonic disperser performs dispersion using energy generated when cavitation (vacuum bubbles) generated by ultrasonic waves is crushed. As specific examples of apparatuses that can be used in the present invention, SMT UH150 and Japan Examples include Seiki Seisakusho US-300T. The high-speed agitation type disperser disperses particles by the shearing force in the vicinity of the agitation blade that is agitated at high speed. 3.7 etc. are mentioned.

  The carbonate fine particles are subjected to surface modification treatment and further treated with a dispersant, and then the dispersion is dropped into a resin binder solution described later and mixed. During mixing, it is preferable to carry out the resin binder liquid with sufficient stirring using a dispersing machine. Examples of the dispersing machine preferably used in the present invention include 2 to 3 roll mills, high-speed stirring mixers, ball mills, bead mills, sands. A grind mill etc. can be mentioned, and it is desirable to use a bead mill etc. in the present invention. In addition, a small amount of a resin different from the final resin composition or a part of the prescription amount of the resin to be used was added in advance, and dispersion treatment was performed using the disperser when the viscosity was relatively low. A step of finishing by adding the remaining resin to the master solution is preferable. This is because the solvent is deprived from the fine particle dispersion highly dispersed in the solvent by the dissolution of the resin, so that a so-called pigment shock occurs and causes particle aggregation.

<< Resin and Resin Composition >>
For example, when the carbonate fine particles of the present invention are incorporated in an optical film, it is common to use a resin that is optically highly transparent and does not exhibit birefringence. . Examples of the resin having such characteristics include a cellulose ester resin, a cycloolefin resin that is a norbornene-based ring-opening polymer, a polymethyl methacrylate resin, and a polycarbonate resin.

  The cellulose ester resin that can be used in the present invention is a carboxylic acid ester having about 2 to 22 carbon atoms, and is particularly preferably a lower fatty acid ester of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. For example, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate phthalate, etc., JP-A-10-45804, Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate as described in US Pat. No. 8,231,761, US Pat. No. 2,319,052 can be used. Alternatively, an ester of an aromatic carboxylic acid and cellulose and cellulose acylate described in JP-A Nos. 2002-179701, 2002-265639, and 2002-265638 are also preferably used. Among the above descriptions, the lower fatty acid esters of cellulose particularly preferably used are cellulose triacetate and cellulose acetate propionate. These cellulose esters can also be mixed and used.

  Examples of the cycloolefin resin include ZEONEX, ZEONOR manufactured by Nippon Zeon Co., Ltd., TOPAS manufactured by Mitsui Chemicals, Inc., and Arton Co., Ltd., which use norbornene as a monomer. These polymers are known to have excellent thermal stability because they have a low moisture permeability and a high glass transition temperature compared to general general-purpose polyolefins.

  The resin composition of the present invention can be used in various forms such as a spherical shape, a rod shape, a plate shape, a cylindrical shape, a tubular shape, a tubular shape, a fibrous shape, a film shape or a sheet shape, and has a low birefringence and a transparency. Excellent in mechanical properties, mechanical strength, dimensional stability, heat resistance, and low water absorption. Therefore, the resin composition according to the present invention can be preferably used for various optical elements, light guide plates, various optical films, and the like.

  The resin composition according to the present invention is not particularly limited in use, but can be applied as a general transparent member. Specific examples of application include optical discs such as CD, CD-ROM, WORM (recordable optical disc), MO (rewritable optical disc; magneto-optical disc), MD (mini disc), DVD (digital video disc), etc. As a base material, optical films such as light guide plates such as liquid crystal displays, polarizing films, retardation films, light diffusion films, overcoat films, antireflection films, touch panel films, light diffusion plates, optical cards, liquid crystal display elements Examples include substrates.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. Various conditions in the following embodiments can be appropriately changed without departing from the features and spirit of the present invention, and the scope of the present invention should not be construed as being limited by the following examples.

Example 1
<< Preparation of alkaline earth metal carbonate particles >>
[Preparation of alkaline earth metal carbonate particles a]
4000 ml of water (solution A1) was prepared in a 8 L stainless steel reaction vessel. Further, 1000 ml of 1.0 mol / L aqueous solution (solution B1) was prepared from strontium chloride hexahydrate, and 1000 ml of 1.0 mol / L aqueous solution (solution C1) was prepared from sodium carbonate.

(Nucleation process)
While maintaining the solution A1 in the reaction vessel at 5 ° C. and stirring at 1000 rpm, 200 ml of the solution B1 and the solution C1 each cooled to 3 ° C. in consideration of the temperature rise due to reaction heat are added equally using the double jet method. The solution was added to the solution A1 at a rate of 2 minutes. The molar addition rate per mol of alkaline earth metal carbonate formed in the nucleation step is 0.5 mol / min.

(Particle growth process)
Next, while stirring the reaction solution held at 5 ° C., the double jet method was performed while accelerating the flow rate of the remaining amount of the solution B1 and the solution C1 held at 5 ° C. according to the increase in the surface area accompanying particle growth. And added to the liquid in the reaction vessel over 150 minutes. At the end of the nucleation process and between and after the grain growth process, the reaction solution was collected and confirmed using an electron microscope. As a result, no new nuclei were generated in the grain growth process. A part of the obtained reaction product was washed with filtered water, and then an X-ray diffraction spectrum was measured, and it was identified that the reaction product was strontium carbonate.

[Preparation of alkaline earth metal carbonate particles b]
A 4000 ml aqueous solution containing 120 g of polyvinylpyrrolidone (anti-aggregation agent) having an average molecular weight of 140,000, 0.1 mol of strontium chloride hexahydrate, and 0.3 mol of ethylenediamine (a form control agent) in a reaction vessel made of stainless steel having a capacity of 8 L. (Solution A2) was prepared. The pH value of the solution A2 was about 12. Further, 1000 ml of 1.0 mol / L aqueous solution (solution B2) was prepared from strontium chloride hexahydrate, and 1000 ml of 1.0 mol / L aqueous solution (solution C2) was prepared from sodium carbonate.

(Nucleation process / particle growth process)
Preparation of alkaline earth metal carbonate particles 1 was the same as the preparation of alkaline earth metal carbonate particles 1 except that solution A1 was changed to solution A2 and solution B1 and solution C1 were changed to solution B2 and solution C2, respectively. As a result, alkaline earth metal carbonate particles 2 were obtained.

[Preparation of alkaline earth metal carbonate particles c]
In the preparation of the alkaline earth metal carbonate particles 2, the alkaline earth metal carbonate particles 2 were prepared in the same manner as in the preparation of the alkaline earth metal carbonate particles 2 except that the aggregation inhibitor added to the solution A2 was changed to polyvinylpyrrolidone having an average molecular weight of 360,000. Similar metal carbonate particles 3 were obtained.

[Preparation of alkaline earth metal carbonate particles d]
In the preparation of the alkaline earth metal carbonate particles 2, the alkaline earth metal carbonate particles 2 were prepared in the same manner as the alkaline earth metal carbonate particles 2 except that the aggregation inhibitor added to the solution A2 was changed to an average molecular weight of 200,000 polyethyleneimine. Similar metal carbonate particles 4 were obtained.

[Preparation of alkaline earth metal carbonate particles e]
In the preparation of the alkaline earth metal carbonate particles 2, an alkali was obtained in the same manner as the preparation of the alkaline earth metal carbonate particles 2 except that the aggregation inhibitor added to the solution A2 was changed to polyvinyl alcohol having an average molecular weight of 170,000. Earth metal carbonate particles 5 were obtained.

[Preparation of alkaline earth metal carbonate particles f]
In the preparation of the alkaline earth metal carbonate particles 2, the alkaline earth metal carbonate particles 2 were prepared in the same manner as in the preparation of the alkaline earth metal carbonate particles 2 except that the aggregation inhibitor added to the solution A2 was changed to an average molecular weight of 220,000 hydroxyethyl cellulose. Similar metal carbonate particles 6 were obtained.

[Preparation of alkaline earth metal carbonate particles g]
The alkaline earth metal carbonate particles 2 were prepared in the same manner as the alkaline earth metal carbonate particles 2 except that 20 g of polyvinylpyrrolidone having an average molecular weight of 140,000 added to the solution A2 was added. Carbonate particles 7 were obtained.

[Preparation of alkaline earth metal carbonate particles h]
The alkaline earth metal carbonate particles 2 were prepared in the same manner as the alkaline earth metal carbonate particles 2 except that 240 g of polyvinylpyrrolidone having an average molecular weight of 140,000 added to the solution A2 was added. Carbonate particles 8 were obtained.

[Measurement of average particle size and AR]
Each of the alkaline earth metal carbonate particles prepared above was photographed with a scanning electron microscope, the diameter of a circle having an area equal to the projected area of the particles was defined as the particle size, and the individual particle sizes measured for 500 particles Was determined as the average particle size. Similarly, the length (major axis diameter) and diameter (minor axis diameter) of 500 particles are measured, and the ratio (major axis diameter / minor axis diameter) is calculated as the aspect ratio, and the average is obtained. A value was determined and used as an average aspect ratio AR.

  The measurement results are shown in Table 1.

(Measurement of particle size distribution)
A value obtained by multiplying the value obtained by dividing the standard deviation of the individual particle sizes obtained by the measurement of the average particle size by the average particle size was multiplied by 100, and this was used as the particle size distribution. The measurement results are shown in Table 1.

      Particle size distribution [%] = standard deviation of particle size / average particle size particle × 100

  From the results in Table 1, it is considered that the average particle diameter is reduced by using a water-soluble aggregation inhibitor during the particle synthesis, and the effect of preventing aggregation is expressed. Moreover, it turns out that the effect of an anti-aggregation agent is made smaller by making the addition amount 1.0% by mass to less than 6.0% by mass, and the particle size distribution is excellent.

  Furthermore, it can be seen that an anti-aggregation agent having a nitrogen (N) atom in the molecule (for example, PVP, PEI) has a high aspect ratio (AR) of the obtained particles and an excellent particle size distribution. It is presumed that this is because the N atom of the anti-aggregation agent is adsorbed on the particle surface and helps the shape control effect.

Example 2
<< Desalting step / Solvent replacement step >>
The particle dispersion produced in Example 1 was subjected to desalting and solvent replacement by the following method.

[Preparation of alkaline earth metal carbonate particle dispersion 1]
Filter the aqueous dispersion of the alkaline earth metal carbonate a prepared above with a 02 μm membrane filter while maintaining the temperature at 5 ° C. (because of the increase in temperature, it is feared that the particle size will increase due to Ostwald ripening). After performing a desalting step by washing, it was dried. Subsequently, as a solvent replacement step, 30 g of this dried product was dispersed in 270 g of ethanol, 180 mg of stearic acid was added, and ultrasonic irradiation with an ultrasonic disperser was performed for 30 minutes. Thereafter, 5% by mass of solid dispersant SOLSPERSE36600 manufactured by Nippon Lubrizol Co., Ltd. was added to the amount of particles in solid content, followed by ultrasonic irradiation for 60 minutes to obtain alkaline earth metal carbonate particle dispersion 1. .

[Preparation of alkaline earth metal carbonate particle dispersion 2]
Dispersion of alkaline earth metal carbonate particles in the same manner as in the preparation of alkaline earth metal carbonate particle dispersion 1 except that alkaline earth metal carbonate b was used instead of alkaline earth metal carbonate a prepared above. Liquid 2 was obtained.

[Preparation of alkaline earth metal carbonate particle dispersion 3]
Dispersion of alkaline earth metal carbonate particles in the same manner as in the preparation of alkaline earth metal carbonate particle dispersion 1 except that alkaline earth metal carbonate e was used instead of alkaline earth metal carbonate a prepared above. Liquid 3 was obtained.

[Preparation of alkaline earth metal carbonate particle dispersion 4]
As the desalting step, an ultrafiltration apparatus having a filtration membrane having a molecular weight cut off of 300,000 connected in a circulating manner in the system while maintaining the aqueous dispersion of the alkaline earth metal carbonate a prepared above at 5 ° C. ( Concentration operation was performed using Pellicon 2) manufactured by Nihon Millipore Corporation. After concentration to 10% of the original volume, cold water was added and dilution-concentration was repeated three times. As a subsequent solvent replacement step, this aqueous dispersion was diluted with ethanol, and ethanol was added in the same manner, and dilution-concentration was repeated three times.

  The solid content of this ethanol dispersion was measured, 180 mg of stearic acid was added to the dispersion corresponding to 30 g of solid content, and ultrasonic irradiation with an ultrasonic disperser was performed for 30 minutes. Thereafter, 5% by mass of a wet dispersing agent SOLSPERSE 36600 manufactured by Nippon Lubrizol Co., Ltd. was added in solid content with respect to the amount of particles, followed by ultrasonic irradiation for 60 minutes to obtain an alkaline earth metal carbonate particle dispersion 4. .

[Preparation of Alkaline Earth Metal Carbonate Particle Dispersions 5-11]
In the preparation of the alkaline earth metal carbonate particle dispersion 4, the alkaline earth metal carbonate particle dispersion 5 was similarly changed except that the alkaline earth metal carbonate a was changed to the alkaline earth metal carbonates b to h. ~ 11 were prepared.

[Preparation of alkaline earth metal carbonate particle dispersion 12]
The preparation of the alkaline earth metal carbonate particle dispersion 4 was carried out in the same manner as the preparation of the alkaline earth metal carbonate particle dispersion 4 except that it was changed to an ultrafiltration device having a filtration membrane having a fractional molecular weight of 100,000. An alkaline earth metal carbonate particle dispersion 12 was obtained.

[Preparation of Alkaline Earth Metal Carbonate Particle Dispersions 13-16]
In the preparation of the alkaline earth metal carbonate particle dispersion 12, the alkaline earth metal carbonate particle dispersion 13 is the same except that the alkaline earth metal carbonate a is changed to the alkaline earth metal carbonates b to f. ~ 16 were prepared.

[Preparation of Resin Composition Film Sample 1]
The alkaline earth metal carbonate particle dispersion 1 prepared above was added to the resin liquid shown below with high-speed stirring to prepare a dope liquid obtained by blending alkaline earth metal carbonate particles.
Dope solution composition (mixed dope and dispersion)
Dispersion Alkaline earth metal carbonate particle dispersion 1 12.5% by mass
Dope solution Ethanol 1.5% by mass
Dichloromethane 67.0% by mass
Triphenyl phosphate (TPP) 1.6% by mass
Ethyl phthalyl ethyl glycolate (EPEG) 0.4% by mass
Cellulose acetate propionate (CAP) 17.0% by mass
This dope solution was cast on a stainless steel belt, and when the residual solvent reached about 20%, it was peeled off from the belt and dried at 120 ° C. for 15 minutes to obtain a resin composition film 1.

[Production of Resin Composition Film Samples 2 to 16]
The production of the resin composition film sample 1 was the same as the production of the resin composition film sample 1 except that the alkaline earth metal carbonate particle dispersion 1 was changed to the alkaline earth metal carbonate particle dispersions 2 to 16. Resin composition film samples 2 to 16 were obtained.

<< Measurement of amount of aggregation inhibitor in resin composition film >>
The mass of the composition contained in the resin composition film was measured using EXSTAR6000TG / DTA manufactured by Seiko Instruments Inc. Table 2 shows the content [mass%] estimated from the TG weight loss of the aggregation inhibitor component.

<< Measurement of haze of resin composition film >>
Haze was measured using a haze meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS K7136, and the values in terms of film thickness of 100 μm are shown in Table 2.

  As a result of Table 2, when the aggregation inhibitor used at the time of particle | grain synthesis | combination is brought in in a resin film, it turns out that the transparency of a resin composition film is impaired remarkably. Furthermore, when treatment using an ultrafiltration device is performed in the desalting step / solvent replacement step, an anti-aggregation agent is efficiently removed by selecting an ultrafiltration membrane having an optimal fractional molecular weight, and the resin composition It was found that high transparency of the physical film can be achieved.

Example 3
When ions other than the alkaline earth metal of Example 1 were used, for example, calcium carbonate and barium carbonate were used, and it was confirmed that the same effect was obtained as a whole without any special mention.

  Further, in addition to the cellulose resin used in the above-described examples, similarly in the implementation using BR-88 manufactured by Mitsubishi Rayon as an acrylic resin, or Arton G manufactured by JSR as a cycloolefin resin, an alkali having high transparency is similarly used. A resin composition obtained by blending earth metal carbonate particles could be obtained.

Claims (7)

In a method for producing a resin composition comprising alkaline earth metal carbonate particles blended, a particle forming step in which the alkaline earth metal carbonate particles are formed in the presence of an agglomeration inhibitor, and the formed alkaline earth metal A removal step of removing the aggregation inhibitor before mixing the carbonate particles in the resin, and removing the aggregation inhibitor to 1.0% by mass or less based on the resin in the removal step. A method for producing a resin composition, comprising: 2. The method for producing a resin composition according to claim 1, wherein the alkaline earth metal carbonate particles are formed by a double jet method in which alkaline earth metal ions and carbonate ions are reacted. 3. The alkaline earth metal carbonate particles are formed in the presence of an aggregation inhibitor in an amount of 1.0% by mass or more and less than 6.0% by mass with respect to a reaction solution. A method for producing a resin composition. 4. The method according to claim 1, further comprising a desalting step and a solvent substitution step after the particle formation step, wherein at least one selected from the desalting step and the solvent substitution step also serves as the removal step. The manufacturing method of the resin composition of description. At least one selected from the desalting step and the solvent replacement step is a membrane separation method using an ultrafiltration membrane, and the ultrafiltration membrane has a fractional molecular weight capable of passing through the aggregation inhibitor. The manufacturing method of the resin composition of Claim 4. The method for producing a resin composition according to any one of claims 1 to 5, wherein the aggregation inhibitor is a water-soluble polymer containing a nitrogen atom. A resin composition film comprising the resin composition obtained by the method for producing a resin composition according to claim 1.